JP2011185988A - Reflective optical sensor and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflective optical sensor capable of more accurately detecting toner density and a position of a toner pattern. <P>SOLUTION: The reflective optical sensor includes: an illumination system in which light emitting parts E1 to E9 are arrayed; a light receiving system in which light receiving parts D1 to D9 are arrayed; an irradiation microlens array in which irradiation microlenses LE1 to LE9 are arrayed in the same pitch as the pitch of the light emitting parts and the light receiving parts; and a light receiving microlens array in which light receiving microlenses LD1 to LD9 are arrayed in the same pitch as the pitch of the light emitting parts and the light receiving parts. The irradiation microlens and the light receiving microlens both have plano-convex shape, and are different in all of radius of curvature of a lens surface, lens area and lens thickness. The illumination system is constituted so that an axis of the light emitting part passing through the center of each light emitting part and perpendicular to the light emitting part is tilted to a surface of a supporting member so as to go toward the light receiving system in a sub-direction, and the light receiving system is constituted so that an axis of the light receiving part passing through the center of each light receiving part and perpendicular to the light receiving part is tilted to the surface of the supporting member so as to go toward the illumination system in the sub-direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reflective optical sensor and an image forming apparatus.

As an image forming apparatus that forms an image with toner, a copying machine, a printer, a plotter, a facsimile machine, a multifunction printer (MFP), and the like are widely known.
In such an image forming apparatus, generally, an electrostatic latent image is formed on the surface of a “photosensitive drum” that is a latent image carrier, and development is performed to visualize the electrostatic latent image with toner. I have an image.

  There are various development methods for obtaining a toner image, such as a two-component development method using a two-component developer containing toner and a carrier, and a mono-toner development method using a developer composed only of toner. Are known.

Regardless of the development method, in order to obtain a good toner image, the “toner amount to be used for developing the electrostatic latent image” must be appropriate. If a sufficient amount of toner is not supplied to the electrostatic latent image, the image (output image) output from the image forming apparatus becomes an “image with insufficient density”. On the other hand, if the amount of toner supplied to the electrostatic latent image is excessive, the density distribution in the output image is biased toward the “high density side”, resulting in an image that is difficult to see.
In order to check the suitability of the amount of toner used for developing an electrostatic latent image, a latent image carrier that forms an electrostatic latent image or a “toner image on a latent image carrier on a sheet-like recording medium such as transfer paper” It is widely practiced to form a toner density detection pattern (toner pattern) on the transfer belt to be transferred, irradiate the toner pattern with detection light, and determine the suitability of the toner density by changing the amount of reflected light. (Patent Documents 1 to 5 etc.).

  The “toner density” is the “image density” of a toner pattern as a toner image.

The toner pattern is formed under “reference image forming conditions” based on image forming conditions such as the charging potential of the latent image carrier, exposure amount, and developing bias. The intensity of reflected light when irradiated with detection light is Since it changes corresponding to the toner density, it is possible to know the level of toner density under the standard image forming conditions by detecting the amount of reflected light.
A high (low) toner density means that the amount of toner supplied to the electrostatic latent image is large (small), so “control toner replenishment to the development unit” according to the detected toner density. It is possible to obtain an appropriate toner image by adjusting image forming conditions.

  The applicant has previously proposed a new “reflective optical sensor” that detects the toner density of a toner pattern (Patent Document 6).

  An object of the present invention is to realize a reflective optical sensor that can detect the toner density and position of a toner pattern with higher accuracy.

The “reflective optical sensor” of the present invention detects the “toner concentration or position” of the toner pattern formed on the surface of the support member moving in the predetermined sub-direction, or the “toner concentration and position” of the toner pattern. It is a reflection type optical sensor used for.
The “support member” is a member on which a toner pattern is formed, specifically a latent image carrier or a transfer belt.
The “latent image carrier” is a photoconductive photoreceptor (drum or belt), and an electrostatic latent image is formed by charging and exposing the surface.
The “transfer belt” is a belt for transferring a toner image obtained by visualizing an electrostatic latent image formed on a latent image carrier with toner onto a “sheet-like recording medium” such as transfer paper. It can be a “direct transfer belt” that directly transfers the toner image on the latent image carrier to the sheet-like recording medium while conveying the medium, or the toner image on the latent image carrier is transferred and transferred. It can also be an “intermediate transfer belt” for retransferring a toner image to a sheet-like recording medium.

  The direction in which the electrostatic latent image forming surface of the latent image carrier moves or the direction in which the belt surface of the transfer belt moves is the “sub-direction”. In the exposure method in which the latent image carrier is optically scanned, the sub-scanning direction orthogonal to the main scanning direction of the optical scanning corresponds to the “sub-direction”.

  The “toner pattern” is first formed on the support member as an electrostatic latent image pattern, and then developed into a toner image to form a toner pattern. Detection by the reflective optical sensor is performed in a state where the toner pattern is formed on the latent image carrier or is transferred onto the transfer belt.

  The reflective optical sensor according to claim 1 includes an illumination system, a light receiving system, an irradiation microlens array, and a light receiving microlens array.

  The “illumination system” includes N (≧ 3) light emitting units arranged and integrated at equal intervals in one direction, and radiates detection light from each of the light emitting units. An LED can be preferably used as the light emitting unit, and therefore an “LED array” can be preferably used as the illumination system.

  The “light receiving system” is formed by integrating N light receiving portions in one direction at the same pitch as the light emitting portion arrangement pitch. A “photodiode or phototransistor” can be preferably used as the light receiving portion, and therefore a “photodiode array or phototransistor array” can be preferably used as the light receiving system.

The “irradiation microlens array” is formed by integrally arraying N irradiation microlenses having the same shape and “the same positive power” in one direction at the same pitch as the N light emitting units.
The “light-receiving microlens array” is formed by integrally arranging N light-receiving microlenses having the same shape and “the same positive power” in one direction at the same pitch as the N light-receiving portions.

  The arrangement direction of the light emitting part of the illumination system (one direction described above), the arrangement direction of the light receiving part of the light receiving system, the micro lens arrangement direction of the irradiation microlens array, and the microlens arrangement direction of the light receiving microlens array are parallel to each other. It is orthogonal to the sub direction or makes a predetermined angle.

  The illumination system is configured so that the light beam emitted from the light emitting unit is irradiated as detection light to the support member via the irradiation microlens, and the reflected light from the support member enters the light receiving unit via the light receiving microlens. The positional relationship among the light receiving system, the irradiation microlens array, and the light receiving microlens array is defined.

The irradiation microlens array and the light receiving microlens array are formed of the same optical material, and both the irradiation microlens and the light receiving microlens are “plano-convex”.
The irradiation microlens and the light receiving microlens are different from each other in lens surface curvature radius, lens area, and lens thickness.

  The illumination system is inclined such that the light emitting unit axis passing through the center of each light emitting unit and perpendicular to the light emitting unit is “toward the light receiving system” in the sub direction with respect to the support member surface. The light receiving portion axis passing through the center of the portion and perpendicular to the light receiving portion is inclined so as to “go to the illumination system” in the sub direction with respect to the support member surface.

The optical axis of each irradiation microlens is parallel to the light emitting unit axis of the corresponding light emitting unit, and the optical axis of each light receiving microlens is parallel to the light receiving unit axis of the corresponding light receiving unit.
Accordingly, the light emitting unit axis and the light receiving unit axis are inclined so as to “approach each other” toward the support member in the sub direction.

  In the reflection type optical sensor according to the first aspect, the light receiving microlens can be larger than the irradiation microlens in any of the lens surface radius of curvature, the lens area, and the lens thickness. .

  Each of the irradiation microlenses of the reflective optical sensor according to claim 1 or 2 can be “displaced to the light receiving part side relative to the corresponding light emitting part” in the sub direction (claim 3).

  The reflection-type optical sensor according to any one of claims 1 to 3, wherein the i (1 ≦ i ≦ N) -th irradiation microlens from a predetermined side in the irradiation microlens array and the light-receiving microlens array The i (1 ≦ i ≦ N) th light-receiving microlens from the predetermined side forms an “oval or rectangular lens surface in the sub direction”, respectively, and these oval or rectangular lens surfaces However, in the width direction (the direction parallel to the arrangement direction of the light emitting parts in the plane orthogonal to the lens surface optical axis), they can be in contact with each other at the same pitch as the arrangement pitch of the light emitting parts.

  The reflection type optical sensor according to any one of claims 1 to 4, wherein "a first reference light reception amount that is a light reception amount of each light receiving portion when the support member surface is irradiated with detection light" and "support The second reference received light amount is referred to as “the received light amount by the diffuse reflected light” with reference to the “second reference received light amount that is the received light amount of each light receiving portion when the toner pattern on the member is irradiated with the detection light”. A processing means for separating the received light amount by the regular reflection light ”can be provided.

  In this case, in the processing means, “a value obtained by dividing the amount of received light by diffuse reflected light: D (expanded) by the amount of received light by regular reflected light: D (positive): D (expanded) / D (positive)” is calculated. It is preferable to do this (claim 6).

  The reflective optical sensor according to any one of claims 1 to 6, wherein the N light emitting units are divided into m sets in the arrangement direction, and each set has a substantially equal number of light emitting units. The light emission section can be flashed in synchronization with the arrangement order.

The reflection type optical sensor according to any one of claims 1 to 7, wherein the number of light emitting units, light receiving units, irradiation microlenses, and light receiving microlenses: N is
7 ≦ N ≦ 31
It is preferable that the number is an odd number within the range (Claim 8).

  The reason why the value of N is “odd” is that the number of arrays: N has “center”, and the light-emitting portion occupying this center position can correspond to the “center in the main direction” of the toner pattern. is there.

  The image forming apparatus according to the present invention includes a latent image carrier, an electrostatic latent image forming unit, a developing device, and a transfer device. The electrostatic latent image forming unit includes a charging unit and an optical scanning device. And having the reflective optical sensor according to any one of claims 1 to 8 (claim 9).

  The “latent image carrier” is a photoconductive photosensitive member formed in a drum shape or a belt shape.

  The “electrostatic latent image forming means” forms an electrostatic latent image by charging and exposing the latent image carrier.

The “developing device” develops the electrostatic latent image and visualizes it as a toner image.
The “transfer device” transfers the toner image to a sheet-like recording medium using a transfer belt. The transfer belt can be the direct transfer belt described above or an intermediate transfer belt.

The “electrostatic latent image forming means” includes a “charging means” for uniformly charging the peripheral surface of the latent image carrier, and charging and optical scanning of the latent image carrier to produce an electrostatic latent image corresponding to the image information. And an “optical scanning device” to be formed.
The “reflective optical sensor” is used to detect “toner density or position” of a toner pattern formed using a latent image carrier or a transfer belt as a support member, or “toner density and position” of the toner pattern. .

  The image forming apparatus according to claim 9 forms toner images of different colors on a plurality of latent image carriers, and superimposes the plurality of toner images to form a multicolor image (“two-color image” or “full-color image”). A tandem type image forming apparatus.

  As described above, according to the present invention, a novel reflective optical senner and image forming apparatus can be realized. In the reflective optical sensor of the present invention, the positional relationship of the illumination system, the light receiving system, the irradiation microlens array, and the light receiving microlens array is optimized as described above, and the irradiation microlens and the light receiving microlens are By optimizing the optical characteristics, it is possible to effectively increase the amount of light received by the light receiving unit and detect the toner density and position of the toner pattern “more accurately”.

  In particular, the light emitting unit axis of the light emitting element and the optical axis of the irradiation microlens are parallel, and the inclination of the light emitting unit axis and the light receiving unit axis is narrowed toward the surface of the support member. The “light beam portion with high light intensity” can be used as detection light, and the light use efficiency in toner pattern detection can be improved satisfactorily.

  Therefore, the image forming apparatus using the reflective optical sensor of the present invention can perform toner image density control and color toner image overlay accuracy with higher performance, and can realize good image formation.

1 is a diagram for explaining a color printer as an image forming apparatus. FIG. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating an optical scanning device. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. FIG. 6 is a diagram for explaining a toner pattern for position detection. It is a diagram for explaining a toner pattern for density detection. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the toner pattern detection by a reflection type optical sensor. It is a figure for demonstrating the micro lens array of a reflection type optical sensor.

  Hereinafter, embodiments will be described.

  FIG. 1 shows a schematic configuration of a color printer as an embodiment of an image forming apparatus.

  The color printer 2000 is a “tandem multicolor printer” that forms a full color image by superimposing toner images of four colors (black, cyan, magenta, and yellow).

  The color printer 2000 includes an optical scanning device 2010, four photosensitive drums 2030a, 2030b, 2030c, 2030d, four cleaning units 2031a, 2031b, 2031c, 2031d, four charging devices 2032a, 2032b, 2032c, 2032d, and four developing units. Rollers 2033a, 2033b, 2033c, 2033d, four toner cartridges 2034a, 2034b, 2034c, 2034d, transfer belt 2040, transfer roller 2042, fixing roller 2050, paper feed roller 2054, registration roller pair 2056, paper discharge roller 2058, paper feed A tray 2060, a paper discharge tray 2070, a communication control device 2080, a reflective optical sensor 2245, and a printer control device 2090 that comprehensively controls the above-described units are provided.

  In the following, as shown in FIG. 1, an “XYZ three-dimensional orthogonal coordinate system” is assumed, and the direction along the longitudinal direction of each photosensitive drum is defined as the Y-axis direction (direction orthogonal to the drawing of FIG. 1). The direction along the arrangement direction of the photosensitive drums will be described as the X-axis direction.

  The communication control device 2080 controls bidirectional communication with a host device (for example, a personal computer) via a network or the like.

  Each of the photosensitive drums 2030a to 2030d, which is a “latent image carrier”, has a photosensitive layer formed on the surface, and the surface is a “scanned surface” of optical scanning by the optical scanning device 2010. The photosensitive drums 2030a to 2030d are rotated in the direction of the arrow (clockwise) in the plane of FIG. 1 by a rotation mechanism (not shown).

  A charging device 2032a, a developing roller 2033a, and a cleaning unit 2031a are arranged along the rotation direction of the photosensitive drum 2030a so as to surround the photosensitive drum 2030a.

  The photosensitive drum 2030a, the charging device 2032a, the developing roller 2033a, the toner cartridge 2034a, and the cleaning unit 2031a constitute an image forming station (hereinafter also referred to as “K station”) that forms a black image.

  A charging device 2032b, a developing roller 2033b, and a cleaning unit 2031b, which are arranged so as to surround the photosensitive drum 2030b along the rotation direction of the photosensitive drum 2030b, are arranged in an image forming station (hereinafter referred to as “C”) that forms a cyan image. Station)).

  The charging device 2032c, the developing roller 2033c, and the cleaning unit 2031c, which are arranged so as to surround the photosensitive drum 2030c along the rotation direction of the photosensitive drum 2030c, are arranged in an image forming station (hereinafter referred to as “M”) that forms a magenta image. Station)).

  A charging device 2032d, a developing roller 2033d, and a cleaning unit 2031d, which are disposed so as to surround the photosensitive drum 2030d along the rotation direction of the photosensitive drum 2030d, are arranged in an image forming station (hereinafter, “Y”) that forms a yellow image. Station)).

  The charging devices 2032a to 2032d constitute “charging means” and, together with the optical scanning device 2010, constitute “electrostatic latent image forming means”.

  The charging devices 2032a to 2032d uniformly charge the surfaces of the corresponding photosensitive drums 2030a to 2030d, respectively.

The optical scanning device 2010 responds with a light beam modulated for each color image information based on multi-color image information (black image information, cyan image information, magenta image information, yellow image information) from the “higher-level device”. The surface of the photosensitive drum to be scanned is optically scanned in the Y direction.
As a result, the potential is attenuated at the light-irradiated portion on the surface of each photosensitive drum, and an electrostatic latent image corresponding to the image information is formed. The formed electrostatic latent image moves to the corresponding developing roller side as the photosensitive drum rotates.
The configuration of the optical scanning device 2010 will be described later.

The toner cartridge 2034a stores black toner, and the black toner is supplied to the developing roller 2033a. The toner cartridge 2034b stores cyan toner, and the cyan toner is supplied to the developing roller 2033b.
The toner cartridge 2034c stores magenta toner, and the magenta toner is supplied to the developing roller 2033c. Yellow toner is stored in the toner cartridge 2034d, and the yellow toner is supplied to the developing roller 2033d.

Each of the developing rollers 2033a to 2033d rotates, and each color toner from the corresponding toner cartridge is thinly and uniformly applied to the surface thereof.
When the applied toner on the surface of each developing roller comes into contact with the surface of the corresponding photosensitive drum, it adheres to the “potential attenuated portion” of the surface and visualizes the electrostatic latent image as a toner image.
The “toner images having different colors” formed for each photoconductor drum move as the photoconductor drum rotates.

The transfer belt 2040 is an “intermediate transfer belt”, and yellow, magenta, cyan, and black toner images are sequentially transferred from the photosensitive drums 2030d to 2030a onto the transfer belt 2040 at a predetermined timing, and are superimposed on each other to form a color. Form an image.
In this embodiment, the transfer belt 2040 that is an intermediate transfer belt is a “support member on which a toner pattern is formed”, and the direction in which the toner image moves on the transfer belt 2040 is the “sub-direction”. A direction (Y-axis direction) orthogonal to the direction is called a “main direction”.

The recording sheets as “sheet-like recording medium” stored in the sheet feeding tray 2060 are fed one by one from the sheet feeding tray 2060 by the sheet feeding roller 2054 and conveyed toward the registration roller pair 2056.
The registration roller pair 2056 pinches the recording paper fed from the paper feed tray 2060 and feeds it toward “between the transfer belt 2040 and the transfer roller 2042” at a predetermined timing. The transfer roller 2042 transfers a color image to the recording paper surface.
The recording sheet on which the color image is transferred is fixed with the color image by heat and pressure applied from the fixing roller 2050. The recording paper on which the color image has been fixed is discharged onto a discharge tray 2070 via a discharge roller 2058 and sequentially stacked.

  When the “transfer residual toner” on the surfaces of the photosensitive drums 2030a to 2030d is removed by the cleaning units 2031a to 2031d corresponding to the photosensitive drums, the surfaces of the photosensitive drums are again transferred to the corresponding charging devices. Return to the opposite position.

  An optical sensor device 2245 using a reflective optical sensor is arranged on the “−X” side (left side in FIG. 1) of the transfer belt 2040. The optical sensor device 2245 will be described later.

  Next, the configuration of the optical scanning device 2010 will be described.

As shown in FIGS. 2 to 5, the optical scanning device 2010 as one embodiment of the optical scanning device includes four light sources 2200a, 2200b, 2200c, 2200d, four coupling lenses 2201a, 2201b, 2201c, 2201d, 4 aperture plates 2202a, 2202b, 2202c, 2202d, 4 cylindrical lenses 2204a, 2204b, 2204c, 2204d, polygon mirror 2104, 4 fθ lenses 2105a, 2105b, 2105c, 2105d, 8 folding mirrors 2106a, 2106b, 2106c, 2106d, 2108a, 2108b, 2108c, 2108d, 4 toroidal lenses 2107a, 2107b, 2107c, 2107d, 4 light detection sensors 2205a, 2205b, 2205c 2205d, 4 one light detection mirror 2207A, and includes 2207b, 2207c, 2207d, etc. (not shown) scanning control unit.
As shown in FIG. 5, these are assembled at predetermined positions of an optical housing 2300 (not shown in FIGS. 2 to 4).

  Hereinafter, for convenience, a direction corresponding to the main scanning direction of the optical scanning is referred to as a “main scanning corresponding direction”, and a direction corresponding to the sub scanning direction is referred to as a “sub scanning corresponding direction”.

  The direction along the optical axis of the coupling lens 2201a and the coupling lens 2201b is referred to as “w1 direction”, and the main scanning corresponding direction on the optical path from the light source 2200a and the light source 2200b to the polygon mirror 2104 is referred to as “m1 direction”.

  The direction along the optical axis of the coupling lens 2201c and the coupling lens 2201d is “w2 direction”, and the main scanning corresponding direction on the optical path from the light source 2200c and the light source 2200d to the polygon mirror 2104 is “m2 direction”. Note that the sub-scanning corresponding direction on the optical path from the light source 2200a and the light source 2200b to the polygon mirror 2104 and the sub-scanning corresponding direction on the optical path from the light source 2200c and the light source 2200d to the polygon mirror 2104 are both the same as the Z-axis direction. Direction.

  The light source 2200b and the light source 2200c are disposed at positions separated from each other in the X-axis direction, and the light source 2200a is disposed on the “−Z” side of the light source 2200b (see FIG. 3). The light source 2200d is disposed on the “−Z” side of the light source 2200c (see FIG. 4).

  The coupling lens 2201a is disposed on the optical path of the light beam emitted from the light source 2200a, and makes the light beam a substantially parallel light beam. The coupling lens 2201b is disposed on the optical path of the light beam emitted from the light source 2200b, and makes the light beam a substantially parallel light beam.

  The coupling lens 2201c is disposed on the optical path of the light beam emitted from the light source 2200c, and makes the light beam a substantially parallel light beam. The coupling lens 2201d is disposed on the optical path of the light beam emitted from the light source 2200d, and makes the light beam a substantially parallel light beam.

  The aperture plate 2202a has an aperture and shapes the light beam that has passed through the coupling lens 2201a. The aperture plate 2202b has an aperture and shapes the light beam that has passed through the coupling lens 2201b.

  The aperture plate 2202c has an aperture and shapes the light beam that has passed through the coupling lens 2201c. The aperture plate 2202d has an aperture and shapes the light beam that has passed through the coupling lens 2201d.

  The cylindrical lens 2204 a forms an image of the light beam that has passed through the opening of the aperture plate 2202 a in the vicinity of the deflection reflection surface of the polygon mirror 2104 in the “sub-scanning corresponding direction”. The cylindrical lens 2204 b forms an image of the light beam that has passed through the opening of the aperture plate 2202 b in the vicinity of the deflection reflection surface of the polygon mirror 2104 in the “sub-scanning corresponding direction”.

  The cylindrical lens 2204 c forms an image of the light beam that has passed through the opening of the aperture plate 2202 c in the vicinity of the deflection reflection surface of the polygon mirror 2104 in the “sub-scanning corresponding direction”. The cylindrical lens 2204d forms an image of the light beam that has passed through the opening of the aperture plate 2202d in the vicinity of the deflection reflection surface of the polygon mirror 2104 in the “sub-scanning corresponding direction”.

  The polygon mirror 2104 has a four-stage mirror having four deflecting reflecting surfaces as a two-stage structure, and the first-stage (lower) four-face mirror deflects the light beam from the cylindrical lens 2204a and the light beam from the cylindrical lens 2204d, respectively. The second stage (upper stage) four-sided mirror is arranged so as to deflect the light beam from the cylindrical lens 2204b and the light beam from the cylindrical lens 2204c, respectively. The first-stage tetrahedral mirror and the second-stage tetrahedral mirror rotate with a phase shift of 45 ° from each other, and writing scanning is alternately performed in the first and second stages.

  The light beams from the cylindrical lenses 2204 a and 2204 b are deflected on the “−X” side of the polygon mirror 2104, and the light beams from the cylindrical lenses 2204 c and 2204 d are deflected on the “+ X” side of the polygon mirror 2104.

  Each of the fθ lenses 2105a to 2105d has optical characteristics such that the light spot moves at a constant speed in the main scanning direction on the surface (scanned surface) of the corresponding photosensitive drum 2030a to 2030d as the polygon mirror 2104 rotates. It has a non-circular arc surface shape.

  The fθ lenses 2105 a and 2105 b are arranged on the “−X” side of the polygon mirror 2104, and the fθ lenses 2105 c and 2105 d are arranged on the “+ X” side of the polygon mirror 2104.

  As shown in FIG. 5, the fθ lens 2105a and the fθ lens 2105b are stacked in the Z-axis direction. The fθ lens 2105a is opposed to the first-stage quadrilateral mirror, and the fθ lens 2105b is opposed to the second-stage tetrahedral mirror. is doing. The fθ lens 2105c and the fθ lens 2105d are also laminated in the Z-axis direction. The fθ lens 2105c is opposed to the second-stage tetrahedral mirror, and the fθ lens 2105d is opposed to the first-stage tetrahedral mirror.

The light beam from the cylindrical lens 2204a deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030a through the fθ lens 2105a, the folding mirror 2106a, the toroidal lens 2107a, and the folding mirror 2108a, thereby forming a light spot. The light spot moves in the longitudinal direction (Y direction) of the photosensitive drum 2030a as the polygon mirror 2104 rotates, and optically scans the photosensitive drum 2030a.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030a, and the rotational direction of the photosensitive drum 2030a is the “sub-scanning direction” on the photosensitive drum 2030a.

The light beam from the cylindrical lens 2204b deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030b through the fθ lens 2105b, the folding mirror 2106b, the toroidal lens 2107b, and the folding mirror 2108b, thereby forming a light spot. The light spot moves in the longitudinal direction of the photosensitive drum 2030b as the polygon mirror 2104 rotates, and optically scans the photosensitive drum 2030b.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030b, and the rotational direction of the photosensitive drum 2030b is the “sub-scanning direction” on the photosensitive drum 2030b.

The light beam from the cylindrical lens 2204c deflected by the polygon mirror 2104 is irradiated to the photosensitive drum 2030c through the fθ lens 2105c, the folding mirror 2106c, the toroidal lens 2107c, and the folding mirror 2108c, thereby forming a light spot. The light spot moves in the longitudinal direction of the photosensitive drum 2030c as the polygon mirror 2104 rotates, and optically scans the photosensitive drum 2030c.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030c, and the rotational direction of the photosensitive drum 2030c is the “sub-scanning direction” on the photosensitive drum 2030c.

The light beam from the cylindrical lens 2204d deflected by the polygon mirror 2104 is irradiated onto the photosensitive drum 2030d through the fθ lens 2105d, the folding mirror 2106d, the toroidal lens 2107d, and the folding mirror 2108d, thereby forming a light spot. . The light spot moves in the longitudinal direction of the photosensitive drum 2030d as the polygon mirror 2104 rotates, and optically scans the photosensitive drum 2030d.
The moving direction of the light spot at this time is the “main scanning direction” on the photosensitive drum 2030d, and the rotational direction of the photosensitive drum 2030d is the “sub-scanning direction” on the photosensitive drum 2030d.

  A scanning area in the main scanning direction in which image information is written on each photosensitive drum is called an “effective scanning area” or an “image forming area”, but is also called an “effective image area” in this specification.

  The folding mirrors are arranged so that the optical path lengths from the polygon mirror 2104 to the photosensitive drums coincide with each other, and the incident position and the incident angle of the light flux on the photosensitive drum are “equal to each other”. ing.

  Further, the “fθ lens and the corresponding toroidal lens” constitute a surface tilt correction optical system in which the deflection point of the polygon mirror and the surface of the photosensitive drum corresponding thereto are “conjugated to the sub-scanning corresponding direction”. .

An optical system disposed on the optical path between the polygon mirror 2104 and each photosensitive drum is also called a “scanning optical system”.
In the embodiment being described, the “scanning optical system of the K station” is formed by the fθ lens 2105a, the toroidal lens 2107a, and the folding mirrors 2106a and 2108a. Each of the “station scanning optical systems” is configured.
Similarly, the “M station scanning optical system” is composed of the fθ lens 2105c, the toroidal lens 2107c, and the folding mirrors 2106c and 2108c, and the fθ lens 2105d, the toroidal lens 2107d and the folding mirrors 2106d and 2108d are coupled to the “Y station scanning optical system”. Are each configured.

  Of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the K station, “a part of the light beam before starting writing” enters the light detection sensor 2205a via the light detection mirror 2207a.

  Of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the C station, “a part of the light beam before starting writing” enters the light detection sensor 2205b via the light detection mirror 2207b.

  Of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the M station, “a part of the light beam before starting writing” enters the light detection sensor 2205c via the light detection mirror 2207c.

  Of the light beam deflected by the polygon mirror 2104 and passed through the scanning optical system of the Y station, “a part of the light beam before starting writing” enters the light detection sensor 2205d via the light detection mirror 2207d.

  The light detection sensors 2205a to 2205d output signals (photoelectric conversion signals) corresponding to the amount of received light.

  A “scan control device” (not shown) determines the scanning start timing of the corresponding photosensitive drum based on the output signal of each light detection sensor, and starts image writing by optical scanning at the determined timing.

  Next, the optical sensor device 2245 will be described.

  As an example, the optical sensor device 2245 includes four reflective optical sensors 2245a, 2245b, 2245c, and 2245d arranged in the Y direction, as shown in FIG.

The reflective optical sensor 2245a is disposed at a position facing the “vicinity of the + Y side end” of the transfer belt 2040, and the reflective optical sensor 2245d is disposed at a position of the transfer belt 2040 facing the “near the −Y side end”. Has been.
The reflective optical sensor 2245b is disposed on the “−Y side” of the reflective optical sensor 2245a, and the reflective optical sensor 2245c is disposed on the “+ Y side” of the reflective optical sensor 2245d.

  The four reflective optical sensors 2245a to 2245d are arranged so as to be “substantially equidistant” in the Y direction.

As shown in FIG. 7, regarding the Y direction, the center positions of the reflective optical sensors 2245a, 2245b, 2245c, and 2245d are Y1, Y2, Y3, and Y4, respectively.
The toner pattern that faces the reflective optical sensor 2245a in the X direction is toner patterns PP1 and TP1, and the toner pattern that faces the reflective optical sensor 2245b is toner patterns PP2 and TP2.

  Similarly, the toner patterns facing the reflective optical sensor 2245c are toner patterns PP3 and TP3, and the toner patterns facing the reflective optical sensor 2245d are toner patterns PP4 and TP4.

  The toner patterns PP1, PP2, PP3, and PP4 are “position detection patterns”, and the toner patterns TP1, TP2, TP3, and TP4 are “density detection patterns”.

Since the position detection patterns PP1, PP2, PP3, and PP4 have the “same configuration”, in the following, when it is not necessary to distinguish the position detection patterns from each other, the position detection patterns PP1 to PP4 are collectively referred to as “position detection. Also referred to as “use pattern PP”.
As shown in FIG. 8, the position detection pattern PP includes four line patterns (LPY1, LPM1, LPC1, LPK1) parallel to the main direction (Y direction) and four lines inclined with respect to the main direction. Line pattern (LPY2, LPM2, LPC2, LPK2).

  The line patterns LPY1 and LPY2 form “pairs” and are formed with yellow toner, and the line patterns LPM1 and LPM2 form “pairs” and are formed with magenta toner. The line patterns LPC1 and LPC2 form a “pair” and are formed with cyan toner, and the line patterns LPK1 and LPK2 form a “pair” and are formed with black toner.

  The “line pattern pair” is set such that “the interval between two line patterns forming a pair” forms a predetermined interval with respect to the traveling direction (sub-direction) of the transfer belt 2040.

The density detection pattern TP1 shown in FIG. 7 is formed with yellow toner, and the density detection pattern TP2 is formed with magenta toner. The density detection pattern TP3 is formed of cyan toner, and the density detection pattern TP4 is formed of black toner.
Hereinafter, when it is not necessary to distinguish between the density detection patterns, these are collectively referred to as “density detection pattern TP”.

As shown in FIG. 9 as an example, the density detection pattern TP includes five rectangular patterns p1 to p5 (hereinafter referred to as “rectangular patterns”), and the five rectangular patterns p1 to p5 are formed on the transfer belt 2040. Are arranged in a row in the traveling direction (sub-direction), and the gradations of the toner density are different.
In the example of FIG. 9, the toner density increases in the order of the rectangular patterns p1, p2, p3, p4, and p5. That is, the rectangular pattern p1 has the lowest toner density, and the rectangular pattern p5 has the highest toner density.

  The length of each rectangular pattern in the Y-axis direction is Lp, and the length of the transfer belt 2040 in the traveling direction is Wp. In the example in the description, “Lp = 1.0 mm”.

  The gradation of the toner density is adjusted by adjusting the power of the light beam emitted from the light source of the optical scanning device, the duty ratio in the drive pulse supplied to the light source, the developing bias, and the like. It can also be changed by controlling the amount of toner adhering to the surface, or by changing the “area ratio of halftone dots” when the rectangular pattern is constituted by halftone dots.

  Hereinafter, when there is no need to distinguish between the position detection pattern and the density detection pattern, these are collectively referred to as a “toner pattern”.

  When the “position detection process and toner density detection process” of the toner pattern is performed using the reflective optical sensor, the position detection pattern and the position detection pattern are transferred from the printer control device 2090 (see FIG. 1) to the scan control device (not shown). The formation of the density detection pattern is instructed.

  In other words, the scanning control device controls the formation of the toner patterns by controlling the Y station to the K station.

  As shown in FIG. 10, the Y station is controlled by forming line patterns LPY1 and LPY2 at positions Y1, Y2, Y3 and Y4 on the photosensitive drum 2030d, and forming a density detection pattern TP1 at position Y1. It is done as follows.

  As shown in FIG. 11, in the control of the M station, line patterns LPM1 and LPM2 are formed at positions Y1, Y2, Y3, and Y4 on the photosensitive drum 2030c, and a density detection pattern TP2 is formed at the position Y2. It is done as follows.

  As shown in FIG. 12, the control of the C station is such that line patterns LPC1 and LPC2 are formed at positions Y1, Y2, Y3 and Y4 on the photosensitive drum 2030b, and a density detection pattern TP3 is formed at position Y3. It is done as follows.

  As shown in FIG. 13, in the control of the K station, line patterns LPK1 and LPK2 are formed at positions Y1, Y2, Y3 and Y4 on the photosensitive drum 2030a, and a density detection pattern TP4 is formed at the position Y4. To be done.

  The toner pattern formed in the shape of each photosensitive drum in this way is transferred to the transfer belt 2040 at a predetermined timing. In this manner, the position detection pattern PP and the density detection pattern TP are formed at positions Y1, Y2, Y3, and Y4 in the Y direction on the transfer belt 2040, respectively. This state is shown in FIG.

The four reflective optical sensors 2245a, 2245b, 2245c, and 2245d constituting the optical sensor device 2245 have the same configuration and structure, and the configuration and structure will be described below with the reflective optical sensor 2245a as a representative. .
As shown in FIG. 15 as an example, the reflective optical sensor 2245a includes nine light emitting portions E1 to E9, nine irradiation microlenses LE1 to LE9, nine light receiving portions D1 to D9, and nine light receiving portions D1 to D9. It has light receiving microlenses LD1 to LD9 and a “processing device” as processing means (not shown).

  It is preferable that the number of light emitting units / light receiving units is an odd number of about 7 to 31 as described in claim 8, but the “combination of nine light emitting units / light receiving units” shown in FIG. , One of the preferred ones.

  The irradiation microlenses LE1 to LE9 constitute an “irradiation microlens array”, and the light receiving microlenses LD1 to LD9 constitute a “light receiving microlens”. The materials of the irradiation microlens and the light receiving microlens are the same, and the refractive index is 1.53. The same applies to various microlens arrays described below.

FIG. 15A shows the reflective optical sensor viewed from the main direction (the arrangement direction of the detection units), and FIG. 15B shows the reflective optical sensor in the “direction perpendicular to the arrangement direction of the light emitting unit and the light receiving unit”. The state seen from. Note that the symbol “DP1” in FIG. 15B indicates the toner pattern TP1 for toner density detection in the above description. The same applies to the following drawings.
FIG. 15C shows a state in which the detection light beams S1 to S9 emitted from the light emitting units E1 to E9 and irradiated through the irradiation microlenses LE1 to LE9 irradiate the transfer belt 2040. d) shows how the detection light beams S1 to S9 reflected by the transfer belt 2040 are received by the light receiving portions D1 to D9 via the light receiving microlenses LD1 to LD9.
FIG. 15E shows a state in which the detection lights S1 to S9 from the light emitting units E1 to E9 irradiate the toner pattern, and FIG. 15F shows the detection light S1 reflected by the toner pattern. -S9 respectively show the manner in which light is received by the light receiving parts D1-D9.

The nine light emitting units E1 to E9 are arranged at equal intervals in the Y direction. An LED can be used as each light emitting unit. The arrangement pitch of the light emitting parts E1 to E9 (the interval between adjacent light emitting parts) (denoted as Le) can be set to 0.4 mm, for example.
The irradiation microlenses LE1 to LE9 correspond to the light emitting portions E1 to E9 on a one-to-one basis, and as shown in FIG. 15A, each irradiation lens is arranged closer to the light receiving portion than the corresponding light emitting portion. Then, the light beam emitted from the light emitting portion is condensed and directed toward the surface of the transfer belt 2040.
In the following description, as shown in FIG. 15 (c), the light beams emitted from the light emitting units E1 to E9 and condensed by the irradiation microlenses LE1 to LE9 are obtained only from the irradiation lenses corresponding to the respective light emitting units. It passes and irradiates the transfer belt 2040 as detection light S1-S9.

  As shown in FIG. 15A, each “light emitting part axis” of the light emitting parts E1 to E9 is “with respect to the surface of the transfer belt 2040 that is a support member” in the “sub-direction (left-right direction in the figure)”. The optical axes of the irradiation microlenses LE1 to LE9 are parallel to the light emitting unit axis and substantially coincide with the light emitting unit axis.

  In general, the “light emission intensity distribution of the light emitting part” is the strongest on the light emitting part axis, including the LEDs exemplified above as specific examples of the light emitting part. Therefore, the positions and states of the light emitting parts E1 to E9 and the irradiation lenses LE1 to LE9. By determining the positional relationship as described above, it is possible to irradiate the surface of the support member most effectively with the light from the light emitting portion.

The surface of the transfer belt 2040 is smooth, and most of the light irradiated on the surface of the transfer belt 2040 is regularly reflected. As shown in FIG. 15 (d), the light receiving parts D1 to D9, when the detection light from the light emitting parts E1 to E9 irradiates “parts other than the toner pattern (transfer belt surface)”. However, the “regularly reflected light only” of the detection lights S1 to S9 is received.
As shown in FIG. 15A, each light receiving portion is arranged on the optical path of “light beam emitted from the corresponding light emitting portion and regularly reflected on the surface of the transfer belt 2040”. That is, the arrangement pitch of the nine light receiving portions D1 to D9 is equal to the arrangement pitch of the nine light emitting portions E1 to E9.

  As shown in FIG. 15A, the light-receiving part axis of the light-receiving parts D1 to D9 is “light-emitting part E1 that forms a light-emitting system in the sub-direction (left-right direction in the figure) with respect to the surface of the transfer belt 2040 that is a support member. The optical axis of the light receiving microlenses LD1 to LD9 is parallel to the light receiving part axis and substantially coincides with the light receiving part axis.

  The lens surface of each microlens can be formed on a glass substrate or a resin substrate using a known processing method such as photolithography or nanoimprint.

As described above, if the arrangement pitch of the light emitting sections in the sub-direction is 0.4 mm, the center interval between adjacent beam spots is also 0.4 mm, and the light spots formed on the surface of the transfer belt 2040 by each detection light are as follows. The size is about 0.4 mm in diameter.
The light spot by the conventional detection light is usually “about 2 to 3 mm in diameter”.

A PD (photodiode) can be suitably used for each light receiving unit, and each light receiving unit outputs a signal corresponding to the amount of received light.
When it is not necessary to individually specify the light emitting units E1 to E9, an arbitrary light emitting unit is referred to as a light emitting unit Ei, and “irradiation microlens corresponding to the light emitting unit Ei” is referred to as an irradiation microlens LEi, a light emitting unit. The detection light emitted from Ei and passing through the irradiation microlens LEi is denoted as detection light Si.

  The light receiving unit corresponding to the light emitting unit Ei is referred to as a light receiving unit Di, and the light receiving microlens corresponding to the light receiving unit Di is referred to as a light receiving microlens LDi.

  The nine irradiation microlenses LEi (i = 1 to 9) constituting the irradiation microlens array used in the reflective optical sensor shown in FIG. 15 have a lens diameter, a lens surface curvature radius, and a lens thickness. Takes the “same value”. Further, the nine light receiving microlenses LDi (i = 1 to 9) constituting the light receiving microlens array all have the “same value” in lens diameter, lens surface radius of curvature, and lens thickness.

  However, the irradiation microlens LEi and the light receiving microlens LDi have different optical characteristics.

  As shown in FIG. 15A, the irradiation microlens LEi and the light receiving microlens LDi are “convex flat lenses” in which the surface on the side of the transfer belt, which is a support member, is a flat surface and the opposite surface is a convex surface. .

As a specific example, the irradiation microlens LEi has a lens diameter: 0.613 mm, a convex lens surface radius of curvature: 0.430 mm, and a lens thickness: 1.229 mm. The light receiving microlens LDi has a lens diameter: 0.750 mm, a lens surface radius of curvature: 0.380 mm, and a lens thickness: 1.419 mm. Both microlens arrays have a refractive index of 1.53 as described above.
The arrangement pitch (distance between the optical axes) of the irradiation microlenses LEi is 0.4 mm, and the arrangement pitch (distance between the optical axes) of the light-receiving microlenses LDi is also 0.4 mm.

The “inter-lens pitch (distance between the centers of convex lens surfaces) in the sub-direction (left-right direction in FIG. 15A)” of the irradiation microlens LEi and the light-receiving microlens LDi is 0.365 mm.
The “interval in the sub direction” between the light emitting unit Ei and the corresponding light receiving unit Di is 0.500 mm.
Further, the light emitting unit axes of the light emitting units E1 to E9 are inclined by 3 degrees in the sub direction with respect to the direction orthogonal to the surface of the transfer belt 2040, and the light receiving unit axes of the light receiving units D1 to D9 are also orthogonal to the surface of the transfer belt 2040. It is inclined 3 degrees in the sub direction with respect to the direction of

  The distance from the light emitting portion to the irradiation microlens (along the light emitting portion axis) is 0.800 mm, and the distance from the back surface (plane) of the irradiation microlens array to the transfer belt surface as a support member is 5 mm. These distances apply in all examples (models) shown below.

A microlens array of this specification (referring to a combination of an irradiation microlens array and a light receiving microlens array; the same applies hereinafter) is referred to as “model I”.
As described above, in model I, the lens area (lens diameter), the lens surface radius of curvature, and the lens thickness are all different between the irradiation microlens and the light receiving microlens, and the lens diameter and the lens thickness are different from each other. Although the lens LDi is large, the lens surface radius of curvature is large for the irradiation microlens LEi.

  By making the lens diameter of the light receiving microlens larger than the lens diameter of the irradiation microlens, it is possible to increase the amount of received detection light, particularly reflected light that is diffusely reflected by the toner pattern.

  By making the lens surface radius of curvature of the light receiving microlens LDi “smaller than that of the irradiation microlens LEi”, the light receiving portion adjacent to the light receiving portion D5 corresponding to the light emitting portion to be turned on, for example, the light emitting portion E5 at the center in the arrangement direction. The light beams after passing through the light receiving microlenses LD4 and LD6 arranged corresponding to the portions D4 and D6 can be largely refracted, and the “diffuse reflected light” from the toner pattern is separated from the light receiving portion D5. D1, D2, D8, D9, etc. can be reached, and an increase in the amount of light received by each light receiving unit can also be expected.

  Each of the irradiation microlens LEi and the light-receiving microlens LDi is a “convex spherical lens”, and the irradiation microlens LEi has a condensing power on the incident surface (convex spherical surface) of the lens. The exit surface (plane) does not have a condensing power. In the light-receiving microlens LDi, the incident surface (plane) of the lens does not have a condensing power, but the exit surface (convex spherical surface) has a condensing power.

Hereinafter, density detection processing performed using the optical sensor device 2245 will be described.
For simplicity of explanation, the light emitting portions Ei (i = 1 to 9) are individually turned on, and the light receiving portions Di (i = i = 9) when the detection light Si (i = 1 to 9) is regularly reflected by the transfer belt 2040. The maximum value of the received light amount of 1 to 9) is normalized to 1.
FIG. 16A shows the normalized amounts of light received by the light receiving portions D1 to D9 when the light emitting portions E1 to E9 of the reflective optical sensor described with reference to FIG. Yes.
The received light amount in the following description is not an experimental value but a reference value for explaining the density detection process.

In the example shown in FIG. 7, the position detection pattern PP moves to the “detection light irradiation position” before the density detection pattern TP, and the toner pattern position detection process precedes the toner density detection process. However, it is also possible to detect the density detection pattern TP “before the position detection pattern PP” by reversing the creation positions in the sub-direction of the density detection pattern and the position detection pattern. Not even.
In the example in the description, the “main position in the main direction” of the light emitting section E5 in the “array center” of the nine light emitting sections E1 to E9 and the “center position in the main direction” of the toner pattern match. A toner pattern is transferred and formed on the transfer belt 2040. FIG. 16B shows this state.

  That is, in this example, the density detection patterns Tp1 to TP4 using the toners of yellow, magenta, cyan, and black are arranged in a line in the sub direction (vertical direction in the drawing).

  The length in the main direction of each rectangular pattern of the density detection pattern PP: Lp is 1.0 mm, and the pitch of the detection light is 0.4 mm. Therefore, the rectangular pattern is in the state shown in FIG. In a state where the position of the part E5 is located at the center of the main direction of the rectangular pattern), as shown in FIG. 15 (e), the light is irradiated with three detection lights S4, S5, and S6.

The light emitting portions E1 to E9 are sequentially turned on and off, and the position of the toner pattern can be confirmed based on the amount of light received by each light receiving portion at that time. As described above, it is assumed that the light receiving amounts of the light receiving portions D1 to D9 when the light emitting portions E1 to E9 are sequentially turned on / off are as shown in FIG.
The amount of light received by each of the light receiving parts D1 to D9 when the light emitting parts E4 to E6 are "lighted individually" is compared to when the other six light emitting parts E1 to E3 and E7 to E8 are individually lighted. Since it is low (the maximum amount of light received does not reach 1), it can be seen that the toner pattern certainly exists at the position where the detection light beams S4 to S6 are irradiated.
Therefore, in such a case, the detection light S4 to S6 may be used for toner density detection. However, for simplicity of explanation, the “light reception amount distribution when the light emitting portion E5 is turned on” is detected as the toner density detection. It will be used for. This is true for all the examples shown below.

  As an example, when the rectangular pattern moves in front of the reflective optical sensor in FIGS. 15E and 15F, the printer control device 2090 “lights the light emitting units E4 to E6 repeatedly and repeatedly”. .

As illustrated in FIG. 15F, the detection lights S4 to S6 are regularly reflected and diffusely reflected on the surface of the rectangular pattern.
Hereinafter, the regularly reflected light is also referred to as “regular reflected light”, and the diffusely reflected light is also referred to as “diffuse reflected light”.

Each of the reflection type optical sensor processing devices (not shown) is based on the output signals of the light receiving parts D1 to D9 when the detection light S5 irradiates a rectangular pattern. Are respectively obtained and stored in a “memory” (not shown) as detected light reception amounts.
The “memory” is built in the processing device.

  The “middle diagram” in FIG. 16C shows the amount of light received by each light receiving unit Di when the detection light S5 irradiates the rectangular pattern p5. In this state, the regular reflection light received by the light receiving portions D4 to D6 is reduced compared to when the detection light S5 irradiates the surface of the transfer belt 2040, while the diffuse reflection light is received by light other than the light receiving portions D4 to D6. The light is also received at the part.

  In general, as the “toner density in the rectangular pattern Pi” increases, the regular reflection light monotonously decreases and the diffuse reflection light monotonously increases among the reflected light from the rectangular pattern.

  As shown in FIG. 16B, the printer controller 2090 (FIG. 1) determines that “the yellow toner density is based on the amount of light received by each light receiving portion Di when the detection light S5 irradiates the rectangular pattern TP1. It is determined whether or not “appropriate”, and “appropriate magenta toner density” is determined based on the amount of light received by each light receiving portion Di when the rectangular pattern TP2 is irradiated, and each when the rectangular pattern TP3 is irradiated “Appropriateness of cyan toner density” is determined based on the received light amount of the light receiving part Di, and “appropriateness of black toner density” is determined based on the received light quantity of each light receiving part Di when the rectangular pattern TP4 is irradiated. .

  When the printer control device 2090 determines that “the toner density is not appropriate”, the control device 2090 controls the development processing system of the “corresponding station” so that the toner concentration is appropriate.

Next, toner density detection using the amount of light received by each light receiving portion Di will be described.
As shown in FIG. 16 (a), when the irradiated portion of the detection light is “a transfer belt that is a regular reflector with respect to the detection light”, when the light emitting portion E5 is turned on, the regular reflected light from the transfer belt is Light is received only by the light receiving part D5 corresponding to the light emitting part E5 and the light receiving part D4 and the light receiving part D6 adjacent thereto.

When the detection light is irradiated to the toner pattern, as shown in FIG. 16C, the reflected light is received by the “all light receiving portions”.
When the light emitting unit E5 emits light, it can be easily understood that the amount of light received by the light receiving units D1 to D3 and D7 to D9 is “due to diffuse reflected light”. This is because the specularly reflected light is received only by the light receiving portions D4 to D6.
The amount of light received by the light receiving portions D4 to D6 is the amount of light received using both regular reflection light and diffuse reflection light from the toner pattern as components. Since it is difficult to accurately divide the amount of light received by the three light receiving units D4 to D6 into “amount of light received by regular reflection light and a light reception amount by diffuse reflected light”, the light receiving unit is used by using the following two assumptions. The amount of received light in D4 to D6 is handled.

In the “first assumption”, among the “light receiving amounts at the light receiving portions D4 to D6” when the light emitting portion E5 is caused to emit light, the light receiving amount at the light receiving portion D5 is determined by the portion irradiated with the detection light. Regardless of the toner pattern, the amount of light received by “all specularly reflected light” is used.
The amount of light received by the light receiving unit D4 and the light receiving unit D6 includes both the amount of received regular reflected light and the amount of diffuse reflected light due to the toner pattern.
In the handling based on the first assumption (hereinafter referred to as “first handling”), “the amount of light received by the two light receiving portions D4 and D6” is not used for toner density detection. That is, in this handling, when the detection light from the light emitting unit E5 irradiates the toner pattern, the light receiving amounts in the light receiving units D1 to D3 and D7 to D9 are all “light received by diffuse reflected light”.

  In the “second assumption”, the amount of light received by the light receiving unit D5 when the light emitting unit E5 emits light is “regular reflection all” regardless of whether the detection light irradiates the transfer belt surface or the toner pattern. The amount of light received by the light receiving unit D4 and the light receiving unit D6 is determined by using the received light amount distribution when the detection light irradiation portion is a transfer belt and the received light amount distribution when the detection light irradiation portion is a toner pattern. “Divided into the amount of light received by the regular reflection light of the toner pattern and the amount of light received by the diffuse reflection light of the toner pattern”.

  Although the handling based on the second assumption (hereinafter referred to as “second handling”) can “use information on the amount of received light more effectively” than the first handling, it is more complicated than the first handling. It is. The second handling will be described later.

  Here, as a “comparative example to model I” of a microlens array (a combination of an irradiation microlens array and a light-receiving microlens array as described above), “reference model I” is a conventional example of a microlens array model. Will be explained.

The “reference model I” is a model of a microlens array in which the “lens surface curvature radius, lens diameter, lens thickness” of the irradiation microlens and the light receiving microlens are all the same. That is, in the reference model I, the irradiation microlens array and the light receiving microlens array are formed of 18 identical microlenses. Of course, the materials of the irradiation microlens and the light receiving microlens (the refractive index is 1.53 as described above) are the same.
In the reference model I, as described above, each irradiation microlens and each light receiving microlens have the same shape. As a specific example, the micro lens has a lens diameter of 0.613 mm, a lens surface radius of curvature of 0.430 mm, and a lens thickness of 1.228 mm.
The arrangement pitch of the microlenses in the sub direction (the distance between the center of the irradiation microlens LEi and the light receiving microlens LDi) is 0.385 mm. The “interval in the sub direction” between the light emitting unit and the corresponding light receiving unit is 0.500 mm. The tilt in the sub-direction of the light emitting unit axis and the light receiving unit axis, and the tilt of the optical axis of the irradiation microlens and the light receiving microlens are the same as in Model I.

  17A shows a state in which the reference model I is viewed from the main direction, and FIG. 17B shows a state in which the reference model I is viewed from a direction orthogonal to the arrangement surface of the light emitting unit and the light receiving unit.

FIG. 17C shows a state in which the detection lights S1 to S9 emitted from the light emitting portions E1 to E9 irradiate the transfer belt, and FIG. 17D shows the detection light reflected by the transfer belt. S1 to S9 are shown as being received by the light receiving portions D1 to D9.
FIG. 17E shows a state in which the detection lights S1 to S9 from the light emitting units E1 to E9 irradiate the toner pattern, and FIG. 17F shows the detection lights S1 to S1 reflected by the toner pattern. S9 shows a state in which the light receiving units D1 to D9 receive the light. The distance from the back surface (center on the optical axis) of the microlens array to the transfer belt surface is 5 mm.

17A showing the reference model I and FIG. 15A showing the model I, the lens areas (lens diameters) of the light receiving microlenses LD1 to LD9 are compared with those of the reference model I as shown in the model I. It can be seen that “more reflected light” can be guided to the light receiving portions D1 to D9 by making the size larger than that.
Further, in the model I, by making the lens surface radius of curvature of the light receiving microlenses LD1 to LD9 smaller than that of the reference model I, more light beams can be guided to “near the center of the light receiving surface” of the light receiving portions D1 to D9. It is like that.
Although the “received amount of diffusely reflected light” is surely increased by adopting the configuration of the model I, the light receiving microlenses LD1 to LD9 “receive a large lens diameter and reduce the lens surface curvature radius”. The thickness of the microlenses LD1 to LD9 was increased, and the difference in lens thickness from the irradiation microlens was 0.190 mm.

  Next, a “model II” of a microlens array formed by a combination of an irradiation microlens array and a light receiving microlens array will be described.

  In Model II, the lens surface curvature radius, lens diameter, and lens thickness are all different between the irradiation microlens and the light receiving microlens, and the light receiving microlens is “irradiation microlens” in terms of the lens surface curvature radius and lens diameter. The value is larger than that of “Lens”.

  The arrangement pitch of the micro lenses in the sub direction (the distance between the optical axes of the irradiation micro lens LEi and the light receiving micro lens LDi) is 0.375 mm. The “interval in the sub direction” between the light emitting unit and the corresponding light receiving unit is 0.500 mm, which is the same as that of the model I.

  Of course, in model II, all the irradiation microlenses constituting the irradiation microlens array have the same lens surface curvature radius, lens diameter, and lens thickness. All the light-receiving microlenses constituting the light-receiving microlens array have the same lens surface curvature radius, lens diameter, and lens thickness.

In Model II, the lens diameter of the irradiation microlens LEi is 0.613 mm, the lens surface radius of curvature is 0.430 mm, and the lens thickness is 1.229 mm. The light receiving microlens LDi has a lens diameter of 0.750 mm, a lens surface radius of curvature of 0.750 mm, and a lens thickness of 1.200 mm.
In other words, in the model II, the irradiation microlens and the light receiving microlens have the lens surface curvature radius, the lens diameter, and the lens thickness “all different values”, and the light receiving microlens has the lens surface curvature radius and the lens diameter. The value is larger than that of the irradiation microlens.
18A shows a state in which the model II is viewed from the main direction, and FIG. 18B shows a state in which the model II is viewed from the direction orthogonal to the arrangement direction of the light emitting units and the light receiving units. FIG. 18C shows the detection light beams S1 to S9 emitted from the light emitting portions E1 to E9 irradiating the transfer belt. FIG. 18D shows the detection light beams S1 to S9 reflected by the transfer belt. A state in which light is received by the light receiving portions D1 to D9 is shown.
FIG. 18E shows a state in which the detection lights S1 to S9 emitted from the light emitting units E1 to E9 irradiate the toner pattern, and FIG. 18F shows the detection light reflected by the toner pattern. S1 to S9 are shown as being received by the light receiving portions D1 to D9.

Comparing FIG. 18A showing model II and FIG. 17A showing reference model I, in model II, “the lens surface radius of curvature” of light receiving microlens LDi is smaller than in reference model I. Thus, the light beam irradiates a wide light receiving range of the light receiving portion Di while suppressing “decrease in the number of light beams” reaching the light receiving portion Di.
The reason why the light beam is irradiated over a wide range of the light receiving part Di is that the influence of “sensitivity unevenness” in the light receiving part is taken into consideration. Since the “difference in lens thickness” between the irradiating microlens and the light receiving microlens is also reduced, the processability is also improved.

  Next, “Model III” will be described as a third model of the microlens array capable of increasing the reflected light of the detection light.

In Model III, the lens curvature radius, lens diameter, and lens thickness are “all different values” between the irradiation microlens and the light receiving microlens, and the lens curvature radius, lens diameter, and lens thickness are received. The microlens for use is larger than the microlens for irradiation in all items.
At that time, compared with the model I, “the overall size of the irradiation microlens and the light receiving microlens (the sum of the lens diameters of the irradiation microlens and the light receiving microlens”) is substantially the same, and the lens diameter Only the distribution ratio was changed.
Further, the irradiation microlens LEi is further shifted to the light receiving system side than in the case of the model I, so that more light beams are guided to the light receiving unit.
The lens diameter of the irradiation microlens LEi was 0.550 mm, and the lens diameter of the light receiving microlens was 0.800 mm. Then, the radius of curvature of the lens surface of the irradiation microlens LEi is set to 0.470 mm so that the beam diameter of the detection light is 0.500 mm or less on the surface of the transfer belt as the support medium.
The lens thickness of the irradiation microlens LDi is 1.189 mm.
Considering the processability of the microlens array, the influence of the sensitivity unevenness in the light receiving portion Di is set so that “the lens thickness of the light receiving microlens LDi is approximately the same as the lens thickness of the irradiation microlens LEi”. In consideration of the condition that the radius of curvature of the lens surface of the light receiving microlens LDi is approximately the same as that of the model II so that “the light received in a wide range of the light receiving portion Di is irradiated” in consideration. The lens surface radius of curvature was optimized.
The light emitting unit axis, the light receiving unit axis, and “the inclination in the sub-direction of the optical axis of the irradiation microlens and the light receiving microlens” are the same as those of the model I.

As a result, the radius of curvature of the light receiving microlens LDi was 0.750 mm, and the “interval in the sub-direction (distance between lens centers)” between the irradiation microlens LEi and the light receiving microlens LDi was 0.335 mm.
The lens thickness of the light-receiving microlens LDi was 1.216 mm, and the “lens thickness difference” from the irradiation microlens LEi was 0.027 mm. The “interval in the sub direction (center interval)” between the light emitting unit LEi and the corresponding light receiving unit LDi is 0.500 mm.

  FIG. 19A shows the model III viewed from the main direction, FIG. 19B shows the model III viewed from the direction orthogonal to the arrangement direction of the light emitting and light receiving units, and FIG. A mode that detection light S1-S9 inject | emitted from the light emission parts E1-E9 has irradiated the transfer belt is shown.

FIG. 19 (d) shows how the detection light beams S1 to S9 reflected by the transfer belt are received by the light receiving portions D1 to D9, and FIG. 19 (e) shows the detection light emitted from the light emitting portions E1 to E9. FIG. 19 (f) shows how the detection light beams S1 to S9 reflected by the toner pattern are received by the light receiving portions D1 to D9, respectively. ing.
Comparing FIG. 19A showing the model III and FIG. 18A showing the model II, in the model III, the lens diameter of the irradiation microlens is smaller than that of the model II. By shifting LEi “more toward the light receiving system”, the number of light rays reaching the light receiving microlens LDi is increased, and by increasing the lens diameter of the light receiving microlens LDi, the number of light beams guided to the light receiving portion Di is increased. .

  For this reason, in the model III, the reflected detection light, particularly the diffuse reflection light from the toner pattern, reaches the “light receiving portion” more than in the case of the model II.

Next, a case where the “second handling” is applied to the model I, the model II, the model III, and the reference model I will be described.
First, the case where “second handling” is applied to the model I will be described.

As described above, in the “first handling”, when the detection light from the light emitting unit E5 “irradiates the toner pattern”, the amount of light received by the light receiving unit D5 is regarded as “the amount of light received by regular reflection light”, and the toner pattern. The received light amounts of the light receiving part D4 and the light receiving part D6 in which “the amount of received light of regular reflected light and the amount of received diffuse reflected light are mixed” are not used for toner density detection.
Since it is difficult to “accurately divide the amount of light received by the light receiving unit D4 and the light receiving unit D6 into the amount of regular reflection light and the amount of diffuse reflection light received from the toner pattern, As in the case of handling, the amount of light received by the light receiving portion D5 corresponding to the light emitting portion E5 that is lit is “all specularly reflected light” whether the detection light irradiates the transfer belt surface or the toner pattern. Is the amount of received light.

  When the toner pattern is irradiated with the detection light, the amount of received light in the light receiving portions D1 to D3 and D7 to D9 is “the amount of received diffusely reflected light” as in the first handling.

  The remaining three light receiving portions D4, D5, and D6 are separated into "light amount of regular reflection light" and "light reception amount of diffuse reflection light", but the light reception portion corresponding to the light-emitting portion E5 that is lit. Since the received light amount of D5 is “all received light amount of specular reflected light”, the received light amount of the light receiving parts D4 and D6 is separated into “received light amount of regular reflected light” and “received light amount of diffuse reflected light”. That's fine.

When the transfer belt is irradiated with detection light, the received light amount of the light receiving unit D4 is A0, the received light amount of the light receiving unit D5 is B0, and the received light amount of the light receiving unit D6 is C0. When the detection light irradiates the toner pattern, the received light amount of the light receiving unit D4 is A1, the received light amount of the light receiving unit D5 is B1, and the received light amount of the light receiving unit D6 is C1.
Even if the portion irradiated with the detection light “changes from the transfer belt to the toner pattern”, the light receiving distribution ratio of “the amount of received regular reflection light” in each light receiving portion does not change.
That is, regarding the light receiving portions D4 and D5, the “ratio of the amount of received light of the specularly reflected light” received by both of them is when the detection light is radiating the transfer belt and the toner pattern. And it does not change. When the transfer belt is irradiated, “the ratio of the received light amount: A0 / B0” is the ratio of the received light amount of the specularly reflected light. Therefore, when the portion irradiated with the detection light is a toner pattern, the light receiving unit D4. Received light amount: “B1 · A0 / B0” obtained by multiplying A0 by B0 and B1 is the amount of regular reflected light, and “A1− (B1 · A0 / B0)” is the amount of diffusely reflected light received. It becomes.

  Similarly, when the toner pattern is irradiated with the detection light S5, the amount of light received by the light receiving portion D6: “B1 · C0 / B0” obtained by multiplying B0 by the value obtained by dividing C0 by B0 is the amount of received regular reflection light. Thus, “C1− (B1 · C0 / B0)” is the amount of diffusely reflected light received.

  In this way, the amount of light received by the light receiving portions D4 and D6 can be separated into “the amount of light received by regular reflection light and the amount of light received by diffuse reflection light”. The model II, the model III, and the reference model I can be similarly separated into “the amount of received light of regular reflected light and the amount of received light of diffuse reflected light”.

It is assumed that the second handling is applied to the model I and “the amount of light received by each light receiving portion is as shown in FIG. 20A” when the transfer belt and the toner patterns p1 to p5 are detected.
The received light amount shown in FIG. 20 is the above-mentioned “reference value for explanation”.
FIG. 20B shows a result of dividing the received light amount of regular reflected light and the received light amount of diffuse reflected light in the detection of the toner pattern p1 by the second handling. FIG. 20C shows the result of dividing the received light amount of regular reflected light and the received light amount of diffuse reflected light in the detection of the toner pattern p2 by the second handling. FIG. 20D shows a result of dividing the received light amount of regular reflected light and the received light amount of diffuse reflected light in the detection of the toner pattern p3 by the second handling.
FIG. 20E shows the result of dividing the received light amount of specularly reflected light and the received light amount of diffusely reflected light from the viewpoint of the toner pattern p4 by the second handling. FIG. 20F shows a result of dividing the received light amount of regular reflected light and the received light amount of diffuse reflected light in the detection of the toner pattern p5 by the second handling.

“Total sum of received light amounts of specularly reflected light” is D (positive), and “total sum of received light amounts of diffusely reflected light” is D (expanded).
FIG. 20G-1 shows the change in “D (positive)” when the toner patterns p1 to p5 are detected. As shown, D (positive) decreases as the toner density (horizontal axis) increases.
This is because as the toner density is higher, the more toner is attached, the less regular reflection light is reduced. The toner density and “D (positive)” have a one-to-one correspondence. In other words, the toner density corresponding to the measured D (positive) can be obtained by measuring D (positive).

FIG. 20G-2 shows a change in “D (expansion)” when the toner patterns p1 to p5 are detected. D (expansion) increases monotonously from toner patterns p1 to p4, but starts decreasing in toner patterns p4 to p5.
Intuitively, D (expansion) seems to be “as the density of the toner constituting the rectangular pattern increases, the amount of toner adhering increases and increases due to an increase in diffuse reflection light”. This is not the case with h). This is because the detection output result is subtracted.

FIG. 20 (g-3) shows the result of obtaining D (expanded) / D (positive).
The vertical axis D (expanded) / D (positive) in FIG. 20 (g-3) is a “monotonic function” that increases as the density of the toner forming the rectangular pattern increases in the order of the rectangular patterns p1 to P5. ing. Therefore, if this “D (expanded) / D (positive)” is measured, the toner density corresponding to each rectangular pattern (horizontal axis in FIG. 20 (g-3)) is obtained.

In FIG. 20 (g-4), the received light amount of the specularly reflected light shown in FIG. 20 (g-1) is normalized by “reference value (here, the received light amount of the specularly reflected light on the transfer belt surface)”. Relative specular reflectance "is shown.
In FIG. 20 (g-5), “D (expanded) / D (positive)” shown in FIG. 20 (g-3) is “reference value (diffuse reflected light contribution at maximum density)”. Indicates the normalized value.

  As described above, a new value is obtained by using a value obtained by dividing the divided output of the diffuse reflected light contribution: D (expanded) by the divided output of the regular reflected light contribution: D (positive): D (expanded) / D (positive). The value may be obtained, and the toner density may be obtained from this value.

  Therefore, as shown in FIG. 20, according to the above-mentioned “second handling”, toner density detection is performed by effectively using the received light amounts of the light receiving portions D1 to D9 for the models I to III and the reference model I. Can be performed.

First, in connection with the example shown in FIG. 16, it is stated that “the light emitting portions E1 to E9 are sequentially turned on and off, and the position of the toner pattern can be confirmed based on the amount of light received by each light receiving portion at that time”. It was. In this case, if the “time taken to sequentially turn on / off the light emitting portions E1 to E9” is long, the toner pattern moves in the sub-direction during this time. It is conceivable that the positional relationship changes and affects the detection accuracy.
In such a case, as in the seventh aspect of the invention, the N light emitting portions are divided into “m sets in the arrangement direction so that each set has a substantially equal number of light emitting portions. It is possible to have an irradiation control device that causes the parts to “blink in synchronization with the arrangement order”.

As in the examples described above, when N = 9, this can be divided into three sets in the arrangement direction, and three light emitting units can be distributed to each set.
That is, the light emitting units E1 to E3 are a first set, the light emitting units E4 to E6 are a second set, and the light emitting units E7 to E9 are a third set.

Then, the first to third sets of light emitting units are blinked in “synchronized with the arrangement order”.
That is, “the first set of light emitting units E1, the second set of light emitting units E4, and the third set of light emitting units E7” are blinked simultaneously, and then “the first set of light emitting units E2 and the second set of light emitting units E5 and The third set of light emitting units E8 "are simultaneously flashed, and then the" first set of light emitting units E3, the second set of light emitting units E6, and the third set of light emitting units E9 "are simultaneously flashed.

  In this way, compared with the case where the light emitting portions E1 to E9 are sequentially blinked, the number of times all nine light emitting portions are blinked can be reduced to three times, and the amount of displacement of the toner pattern during this period is also small. Further, the length in the sub-direction of the rectangular toner pattern p1 or the like: Wp (see FIG. 9) can be reduced, or detection can be handled even when the moving speed of the toner pattern is increased.

  The microlens array described above with respect to the above-mentioned various models is “the irradiation microlens array and the light receiving microlens array are formed as separate bodies” as shown in FIG. The irradiation microlens array and the light receiving microlens array may be formed integrally with each other.

  In FIG. 15A and the like, the state viewed from the “main direction” that is the arrangement direction of the irradiation microlens and the light receiving microlens is shown, and the arrangement state of these microlenses is not particularly mentioned in the above description. It was.

  In each model described above, the arrangement pitch in the main direction of the irradiation microlenses is 0.4 mm.

  On the other hand, for example, in “Model I”, the lens diameter of the irradiation microlens LEi is 0.613 mm, and the lens diameter of the light receiving microlens LDi is 0.750 mm.

  Accordingly, when the irradiation microlens LEi and the light-receiving microlens LDi are the above-mentioned “circular lens surface having a lens diameter”, these microlenses are “arrayed in the main direction at an array pitch of 0.4 mm”. It is not possible.

  In other words, the arrayed arrayed microlenses for irradiation and light reception have a “lens surface width in the main direction” of 0.4 mm.

Therefore, the microlens array of each model described above is as shown in FIG. 22A when viewed from the direction of the optical axis of each microlens.
That is, the symbol DMLA shown in the upper diagram of FIG. 22A is a “light-receiving microlens array”, and the nine light-receiving microlenses LD1 to LD9 are in close contact with each other in the main direction (left-right direction in the figure). Is formed.

  The symbol EMLA shown in the lower part of FIG. 22A is an “irradiation microlens array”, and nine light receiving microlenses LE1 to LE9 are formed in close contact with each other in the main direction (the left-right direction in the figure). ing.

  The width in the arrangement direction of the irradiation microlenses LE1 to LE9, that is, the lens surface width is 0.4 mm. In the above description, what is described as the “lens diameter” for the irradiation microlens is shown in FIG. In the figure below, the lens surface width DLE in the sub direction is indicated.

  The width in the arrangement direction of the light receiving microlenses LD1 to LD9, that is, the lens surface width is 0.4 mm. In the above description, the “lens diameter” of the light receiving microlens is shown in the upper diagram of FIG. The lens surface width DLD in the sub direction.

  FIG.22 (b) is a modification of the figure (a), and the code | symbol is made common with the figure (a). In this example, the irradiation microlenses LE1 to LE9 constituting the irradiation microlens array EMLA have a rectangular shape and are closely arranged in the main direction (the left-right direction in the drawing). In addition, the light receiving microlenses LD1 to LD9 constituting the light receiving micro lens array DMLA are also rectangular, and are closely arranged in the main direction (left-right direction in the figure).

  That is, the irradiation microlens array EMLA described above includes the i (1 ≦ i ≦ 9) th irradiation microlens LEi from the predetermined side in the irradiation microlens array and the predetermined microlens array in the light receiving microlens array. The i (1 ≦ i ≦ 9) th light-receiving microlens LDi from the side forms an “oval or rectangular lens surface in the sub direction”, respectively, and these oval or rectangular lens surfaces are In the width direction (the horizontal direction and the main direction in FIG. 22), they are in contact with each other at the same pitch as the arrangement pitch of the light emitting portions.

Next, “toner pattern position detection processing” using a reflective optical sensor will be described.
As an example, a reflection type optical sensor using the above-described model I microlens array is used.
As shown in FIG. 21B, the position detection pattern is transferred onto the transfer belt 2040 so that the center position of the light emitting portion E5 and the center position of the toner pattern coincide with each other in the main direction. .

The printer control device 2090 shown in FIG. 1 measures the timing when the position detection pattern PP approaches the reflective optical sensor, and continuously turns on the light emitting unit E5.
The detection light from the light emitting portion E5 sequentially irradiates the line patterns LPY1 to LPK2 as the transfer belt 2040 rotates (see FIGS. 21C and 21A).

  Then, the printer control device 2090 traces the output signal of each light receiving unit in time, and the time from when the detection light irradiates the line pattern LPY1 to the line pattern LPM1: Tym, line shape Time from irradiation of the pattern LPM1 to irradiation of the line pattern LPC1: Tmc, time from irradiation of the line pattern LPC1 to irradiation of the line pattern LPK1: Tck is detected (FIG. 21C). (See (B)).

  The output signal of each light receiving unit is amplified and inverted, and passes through a comparison circuit that compares with a predetermined reference value.

If the time: Tym, Tmc, and Tck are substantially the same, the printer control apparatus 2090 determines that “the positional relationship in the sub-direction between the color toner images is appropriate”, and the times: Tym, Tmc, and Tck are “substantially the same”. If not, it is determined that “there is a deviation in the positional relationship between the sub-directions of the respective color toner images”.
When the printer control device 2090 determines that there is a deviation in the positional relation, the printer control apparatus 2090 obtains the “positional deviation amount” from the time differences among the times; Tym, Tmc, and Tck, and sends the deviation amount to the scanning control apparatus. send. The scanning control device adjusts the timing of the optical scanning start in the corresponding station so that the inputted “deviation amount” is zero.

  The printer control device 2090 also irradiates the line pattern LPM2 after irradiating the line pattern LPM1 after the time when the detection light irradiates the line pattern LPY2 until the line pattern LPY2 is irradiated. Time until irradiation: Tm, time from irradiation of the line pattern LPC1 to irradiation of the line pattern LPC2: Tc, time from irradiation of the line pattern LPK1 to irradiation of the line pattern LPK2: Tk It detects (refer FIG. 21 (c) (B)).

  Then, the printer control apparatus 2090 compares the times: Ty, Tm, Tc, and Tk with “a reference time predetermined for these times”. If all of the times: Ty, Tm, Tc, and Tk are the same as the reference times for these, the printer control device 2090 determines that “the positional relationship between the color toner images in the main direction is appropriate”.

For example, if the time: Ty is different from the reference time, the printer control device 2090 obtains the “position shift amount in the main direction: ΔS” of the yellow toner image using the following equation (1) (FIG. 22 ( d) See (A) and FIGS. 22 (d) and 22 (B)).
ΔS = V · ΔT · cot θ (1)
In Expression (1), “V” is the moving speed of the transfer belt 2040 in the sub-direction, “ΔT” is the difference between time: Ty and its reference time, and “θ” is the inclination angle with respect to the main direction of the line pattern LPY2. is there. The calculated misregistration amount: ΔS is input to the scanning control device.

  The scanning control device adjusts the Y station so that “the input positional deviation amount: ΔS becomes 0”. The printer control device 2090 also obtains “the center position of the toner pattern in the main direction” from the positional deviation amount: ΔS.

  In the above description, the toner pattern on the transfer belt 2040 is detected. However, the present invention is not limited to this, and depending on the form of the image forming apparatus, the toner pattern on the photosensitive drum or the intermediate transfer belt is detected. Needless to say, you can.

  As the image forming apparatus, the color printer 2000 including a plurality of photosensitive drums has been described. However, the present invention is not limited to this. For example, the present invention can be applied to a printer that includes one photosensitive drum and forms a single color image.

  Further, it may be an image forming apparatus other than a printer, for example, a copier, a facsimile, or a multifunction machine in which these are integrated.

  Although not described, the present invention is also applicable to the case where the toner density and position of the toner pattern or the toner density or position on the photosensitive drum after the toner adheres to the electrostatic latent image is detected by the developing roller. A reflective optical sensor is applicable.

In addition, the case of “transfer belt with smooth surface (regular reflection only on the surface)” was given above, but regarding “transfer belt with non-smooth surface (reflection on the surface includes diffuse reflection)” The above idea can also be applied.
That is, if the “detection output distribution by the regular reflector” can be measured by using an appropriate means, it can be “divided into a regular reflection contribution and a diffuse reflection contribution” by using it.
For example, the detection output distribution can be measured in advance using a regular reflector, and the measured distribution can be stored in a memory or the like, or a “surface with a smooth surface” can be formed on a part of the transfer belt. Further, regular reflection at this portion can be detected, or a movable regular reflector can be provided in the image forming apparatus, and the regular reflector can be moved and detected when necessary.

  As is apparent from the above description, the first reference received light amount, which is the amount of light received by each light receiving unit when the surface of the support member is irradiated with detection light, With reference to the second reference light reception amount that is the light reception amount of each light receiving portion when the toner pattern is irradiated with the detection light, the second reference light reception amount is determined based on the diffused reflection light reception amount and the regular reflection light. In the embodiment described above, the printer control device 2090 realizes the “processing means for separating the received light amount by the processing means” and the irradiation control device of claim 8.

Ei light emitting part
Di light receiver
LEi Irradiation Microlens
LDi micro lens for light reception
TP1 Toner pattern for toner density detection

JP-A-1-35466 JP 2004-21164 A JP 2002-72612 A JP 2004-309292 A JP 2004-309293 A JP 2009-258601 A

Claims (10)

A reflective optical sensor used for detecting the toner density or position of a toner pattern formed on the surface of a support member moving in a predetermined sub-direction, or the toner density and position of the toner pattern,
An illumination system in which N (≧ 3) light emitting units are arranged and integrated at equal intervals in one direction, and radiates detection light from each of the light emitting units;
A light receiving system in which N light receiving portions are arranged and integrated in one direction at the same pitch as the light emitting portion;
An irradiation microlens array in which N irradiation microlenses having the same shape and the same positive power are arrayed and integrated in one direction at the same pitch as the N light emitting units,
A light receiving microlens array in which N light receiving microlenses having the same shape and the same positive power are arrayed and integrated in one direction at the same pitch as the N light receiving portions, and
The arrangement direction of the light emitting unit of the illumination system, the arrangement direction of the light receiving unit of the light receiving system, the micro lens arrangement direction of the irradiation micro lens array, and the micro lens arrangement direction of the light receiving micro lens array are parallel to each other and in the sub-direction. Perpendicular to or at a predetermined angle to
The light beam emitted from the light emitting unit is irradiated as detection light onto the support member through the irradiation microlens, and the reflected light of the detection light from the support member enters the light reception unit through the light receiving microlens. As described above, the positional relationship of the illumination system, the light receiving system, the irradiation microlens array, the light receiving microlens array is determined,
The irradiation microlens array and the light receiving microlens array are formed of the same optical material, and both the irradiation microlens and the light receiving microlens have a plano-convex shape,
The irradiation microlens and the light receiving microlens are different from each other in lens surface radius of curvature, lens area, and lens thickness.
The illumination system is inclined such that the light emitting unit axis passing through the center of each light emitting unit and perpendicular to the light emitting unit is directed toward the light receiving system in the sub direction with respect to the support member surface.
The light receiving system is inclined such that a light receiving unit axis that passes through the center of each light receiving unit and is perpendicular to the light receiving unit is directed toward the illumination system in the sub direction with respect to the support member surface.
The optical axis of each of the irradiation microlenses is parallel to the light emitting part axis of the corresponding light emitting part,
A reflection type optical sensor, wherein an optical axis of each of the light receiving microlenses is parallel to a light receiving unit axis of a corresponding light receiving unit. The reflective optical sensor according to claim 1,
A reflection-type optical sensor characterized in that the light-receiving microlens has a larger lens surface radius of curvature, lens area, and lens thickness than an irradiation microlens. The reflective optical sensor according to claim 1 or 2,
Each of the irradiation microlenses is disposed in the sub-direction so as to be shifted from the corresponding light emitting unit toward the light receiving unit. The reflective optical sensor according to any one of claims 1 to 3,
The i (1 ≦ i ≦ N) -th irradiation microlens from a predetermined side in the irradiation microlens array and the i (1 ≦ i ≦ N) th light-receiving microlens from the predetermined side in the light-receiving microlens array. Each lens has an oval or rectangular lens surface in the sub-direction,
A reflective optical sensor characterized in that these oval or rectangular lens surfaces are in contact with each other at the same pitch as the arrangement pitch of the light emitting portions in the width direction. The reflective optical sensor according to any one of claims 1 to 4,
A first reference received light amount that is a light receiving amount of each light receiving portion when the support member surface is irradiated with detection light, and each light receiving portion when the toner pattern on the support member is irradiated with the detection light. And a second reference received light amount that is a received light amount, and a processing means for separating the second reference received light amount into a received light amount by diffusely reflected light and a received light amount by regular reflected light. Reflective optical sensor. The reflective optical sensor according to claim 5, wherein
Reflective optics characterized by performing a calculation to obtain a value: D (expanded) / D (positive) obtained by dividing a received light amount by diffusely reflected light: D (expanded) by a received light amount by regular reflected light: D (positive) Sensor. The reflective optical sensor according to any one of claims 1 to 6,
N light emitting units are divided into m sets in the arrangement direction, each set has a substantially equal number of light emitting units, and has an irradiation control device that blinks each set of light emitting units in synchronization with the arrangement order. A reflective optical sensor. The reflective optical sensor according to any one of claims 1 to 6,
Number of light emitting units, light receiving units, irradiation microlenses, light receiving microlenses: N
7 ≦ N ≦ 31
A reflection-type optical sensor characterized by being an odd number within the range. A latent image carrier;
An electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image;
A developing device for developing the electrostatic latent image and visualizing it as a toner image;
A transfer device for transferring the toner image to a sheet-like recording medium by a transfer belt;
A reflective optical sensor used to detect the toner density or position of a toner pattern formed using the latent image carrier or transfer belt as a support member, or the toner density and position of the toner pattern;
The electrostatic latent image forming unit includes a charging unit that uniformly charges the latent image carrier, and an optical scanning device that performs optical scanning on the uniformly charged latent image carrier and forms an electrostatic latent image according to image information. And
An image forming apparatus comprising the reflective optical sensor according to any one of claims 1 to 8 as the reflective optical sensor. The image forming apparatus according to claim 9.
A tandem type image forming apparatus that forms toner images of different colors on a plurality of latent image carriers and forms a multicolor image by superimposing the plurality of toner images.

Images