JP2002055572A - Image detecting device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image detecting device and an image forming device capable of accurately detecting a position detecting pattern, and capable of obtaining a color image free from color slurring. SOLUTION: As for the image detecting device provided with a light source means, an illuminating means including an illuminating lens for irradiating a luminous flux from the light source means onto a recording member on which an image is formed, and an image forming means including an image forming lens for forming the image formed on the recording member onto the surface of a light receiving means, and for detecting the image on the recording member based on the signal obtained by the light receiving means, the device is provided with a diaphragm arranged in or near a position having a conjugate relation with the light emitting point of the light source means in the case of making the recording member a mirror reflection surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image detecting apparatus and an image forming apparatus, for example, an image forming section (image forming means).
However, the present invention is suitable for a color image forming apparatus for obtaining a multicolor image (color image) by using a plurality of electrophotographic copying machines, laser beam printers, color printers, printing apparatuses, and the like.

[0002]

2. Description of the Related Art A conventional image forming apparatus for obtaining a multi-color image generally forms images of different colors in a plurality of image forming units, and conveys the paper by a conveying means such as a conveying belt. The multi-color image is formed by transferring the image by superimposing the image on paper. In particular, when multicolor development is performed to obtain a full-color image, even a slight misregistration is exacerbated. For example, in the case of 400 dpi, one pixel is 63.5 μm.
Even an overlap shift of a fraction of m appears as a change in color shift or color misregistration and significantly degrades the image.

Conventionally, multicolor development has been performed using a single image forming unit, ie, the same scanning lens system, that is, optical scanning with the same optical characteristics has been used to alleviate image overlap deviation.
However, this method has a problem that it takes time to output a multiplex image or full color.

[0004] In order to solve this problem, there is a method in which images are formed by different optical scanning devices in order to separately obtain images of each color, and the images of each color are superimposed on paper fed by a transport unit. However, a concern with this method is a color shift at the time of superimposing images.

FIG. 8 is an explanatory diagram of an image detecting device for detecting this color shift.

FIG. 8 shows a recording member 8 which is an intermediate transfer belt.
The position detection pattern (image) 86 drawn on the light source 4 is radiated from the light emitting unit 81a of the light source unit 81, collected by the light collecting unit 81b, and illuminated through the dustproof glass 87.

[0007] The light reflected regularly by the position detection pattern 86 is detected by the light receiving means 83 via the dustproof glass 87, the aperture 85, and the imaging lens 82.

An image forming section (image forming means) is controlled to output an image of each color in accordance with a detection signal detected by the light receiving means 83.

FIG. 9 shows how the light beam emitted from the light source 81 at a radiation angle of 6.8 ° enters the light receiving means 83 in the image detecting device of FIG.

[0010]

In the conventional image detecting apparatus, nothing is specified as to the positional relationship between the light emitting portion of the light source and the stop provided near the imaging lens. For this reason, as shown in FIG. 9, only a very small light flux from the light source 81 is incident on the sensor 83, and a sufficient signal output cannot be obtained from the light receiving means 83. there were. FIG. 10 shows an output waveform when the position detection mark 86 is read by the light receiving signal 83.

[0011] FIG V1 is an output signal when subjected to regular reflection light from the recording member, V ₂ is receiving the diffused light when subjected to detection mark drawn by the toner image (the position detection mark) This is the output signal when the operation is performed.

Generally, the ratio (SN) of the signal output values at this time is
Ratio) V ₁ / V ₂ is larger, the detection accuracy is improved. FIG. 11 shows the relationship between the image density and the signal output when the image detection device that detects the density of the position detection pattern and obtains image information from the position detection pattern is used as the density detection device. FIG. 12 shows the relationship between the regular reflection light on the recording member and the light diffused by the toner.
Shown in

Hereinafter, a description will be given with reference to FIGS.

At point A, no toner rides on the recording member, and only the specularly reflected light from the recording member travels to the sensor. In the region from point A to point B, the specularly reflected light from the recording member and the diffused light from the toner on a part of the recording member travel to the sensor. In this area, the amount of specularly reflected light blocked by the toner image is greater than the amount of diffused light diffused in the toner image, and thus monotonically decreases.

Further, from the intermediate point from point B to point C, the amount of diffused light diffused in the toner image increases, and the signal output increases. In an area where this reversal phenomenon occurs (an area on the right side of the dotted line in the graph), it is impossible in principle to detect density and obtain image information.

In general, the area from the point B to the point C (halftone area) requires the highest detection accuracy, but there is a problem that detection cannot be performed in this halftone area.

According to the present invention, when a color image is obtained by detecting an image (a pattern for position detection) of each color and controlling the image forming unit to perform multicolor development and superimpose images.
An image detecting apparatus and an image capable of detecting an image (position detecting pattern) with high accuracy and easily obtaining a high-quality color image by appropriately setting the configuration of an image detecting apparatus for detecting an image (position detecting pattern). It is intended to provide a forming apparatus.

[0018]

The image detecting apparatus according to the first aspect of the present invention comprises: a light source means; an illuminating means including an irradiation lens for irradiating a light beam from the light source means onto a recording member on which an image is formed; Imaging means including an imaging lens for forming an image on the recording member on the light receiving means surface, an image detecting apparatus for detecting an image on the recording member based on a signal obtained by the light receiving means, When the recording member is a mirror reflection surface, a stop is provided at a position conjugate with the light emitting point of the light source means or in the vicinity thereof.

According to a second aspect of the present invention, when the light emission point of the light source means is imaged at a conjugate position of the light source means, the imaging magnification is β, and the following condition is satisfied: 1 <| β | <7. The feature is that it is characterized.

A third aspect of the present invention is characterized in that, in the first or second aspect of the invention, the aperture of the stop is substantially equal to or smaller than the size of the image of the light emitting point of the light source means.

According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, the stop is disposed between the image forming means and the light receiving means.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the light receiving means detects position information of an image formed on the recording member.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the light receiving means detects the density of an image formed on the recording member.

According to a seventh aspect of the present invention, there is provided the image forming apparatus according to the first aspect.
A color image is formed using the image detecting device according to any one of the above items 1 to 6.

According to another aspect of the present invention, there is provided an image forming apparatus comprising: conveying means for conveying a recording member on which an image is formed; image forming means for forming an image on the recording member; light source means for illuminating the image; Illumination means including an illumination lens for condensing light rays emitted from the light source means toward the image, and imaging means including an imaging lens for guiding reflected light from the image onto a light receiving means surface. The image forming apparatus detects position information of an image on the recording member based on a signal obtained by the light receiving unit, and obtains a color image using the position information. An aperture is provided at a position conjugate with the light emitting point of the light source means or in the vicinity of the light emitting point when the light is specularly reflected.

[0026]

FIG. 1 is a schematic view of a main part of a first embodiment in which an image forming apparatus having an image detecting apparatus according to the present invention is applied to a digital full-color copying machine.

First, the structure and operation of the digital full-color copying machine shown in FIG. 1 will be described.

In the figure, reference numeral 80 denotes a document reading unit, which converts image information of a color image placed on a document glass table 86 by mirrors 83, 84, 85 and a reading lens 82 to C.
It is formed and read on a reading means surface 81 such as a CD. The color image information from the reading unit 81 is input to the full-color image forming unit 10.

The full-color image forming section 10 has first to fourth
Are arranged (image forming units (image forming means) Pa to Pd), and each image forming station (Pa to Pd) is a photosensitive drum (2a to 2d) as an image carrier.
d). In addition, dedicated charging means (3
a to 3d), a scanning optical device (1a to 1d) for irradiating a light beam according to image information onto the photosensitive drum surface, a developing unit (5a to 5d), and a drum cleaning unit (4a to 4d)
d), and transfer means (6a to 6d) and the like. Reference numerals 51a to 51d denote developer containers, which correspond to the respective developing means (5a to 5d), and are provided immediately below the horizontal portions of the scanning optical devices (1a to 1d) and side by side with the vertical portions. The developer is supplied by attaching and detaching a cylindrical developer cartridge.

Here, the image forming stations (Pa to P)
d) are cyan image, magenta image, yellow image,
This is where a black image is to be formed.

On the other hand, each image forming station is (Pa-
An intermediate transfer belt (recording member) 61 in the form of an endless belt is disposed below the photosensitive drums (2a to 2d) so as to pass through Pd), and the intermediate transfer belt 61 is driven by a driving roller 62 and driven rollers 63 and 65. A cleaning means 64 for cleaning the surface of the frame is provided.

The scanning optical device (1a to 1a) in this embodiment
d) is a semiconductor laser as a light source means, incident optical means for guiding a light beam emitted from the semiconductor laser to a polygon mirror, and a light beam deflected by the polygon mirror on a surface of a photosensitive drum (2a to 2d) as an image carrier. Image forming means having an optical element such as a toric lens and a spherical lens, an aspherical lens, etc. to be imaged on, a reflecting mirror as a reflecting member provided between the toric lens and the optical element, and those optical elements. It has a housing means for integrally housing.

In such a configuration, first, the charging means 3a of the first image forming station Pa and the scanning optical device 1
After a latent image of a cyan component of image information is formed on the surface of the photosensitive drum 2a by a known electrophotographic process such as exposure by a, the latent image is formed as a cyan toner image by a developer having a cyan toner by a developing unit 5a. The image is visualized and the cyan toner image is transferred to the surface of the intermediate transfer belt 61 by the transfer unit 6a.

On the other hand, while the cyan toner image is being transferred onto the intermediate transfer belt 61, a magenta component color latent image is formed in the second image forming station Ph. An image is obtained, and the magenta toner image is transferred with high accuracy by the transfer unit 6b onto the intermediate transfer belt 61 that has been transferred at the first image forming station Pa.

Hereinafter, image formation is performed for the yellow image and the black image in the same manner.
When the superimposition of the four color toner images is completed, the four color toner images on the intermediate transfer belt 61 are placed in the paper feed cassette 70 by the secondary transfer roller 66, and the paper feed roller 71 and the transport roller pair 72 The sheet is again transferred (secondarily transferred) onto the sheet material S conveyed at the same timing by the registration roller pair 73. Then, the toner image transferred by the fixing roller pair 74 is heat-fixed to the sheet material S on which the secondary transfer has been completed, and a full-color image is obtained on the sheet material S. The sheet material S on which the full-color image has been formed is applied to the rollers 75 and 7.
6 to the tray 77.

Each of the photosensitive drums (2
In a to 2d), residual toner is removed from each of the photosensitive drums (2a to 2d) by cleaning means (4a to 4d) to prepare for the subsequent image formation.

Reference numeral 69 denotes an image detecting device. In the figure, image detecting devices having the same configuration are arranged at three positions on the back side, center, and near side of the intermediate transfer belt 61 or at two positions on the back side and the near side.

The surface of the intermediate transfer belt 61 is close to a mirror surface.

In this embodiment, before the image forming process is performed, each of the image forming units Pa, Pb, Pc and Pd is placed on the intermediate transfer belt 61 by four image forming units Pa and P, respectively.
A position detection mark (pattern) 69a as an image corresponding to b, Pc, and Pd is formed.

That is, four images are formed as a whole. Hereinafter, for simplicity, the left and right position detection marks are treated as one.

Prior to executing the above-described process of the image forming section, the image detecting device 69 performs the operation of each of the photosensitive drums 2a to 2a.
The position information 69a of the image formed in the non-image forming area d and transferred in the transport direction of the intermediate transfer belt 61 is detected. Each of the image forming units Pa, Pb, Pc, and Pd is controlled by a control unit (not shown) based on the detected detection signal.

As a result, a color image without color shift is formed on the intermediate transfer belt 61.

FIG. 2 is a sectional view of a main part of an image detecting device 69 used in the image forming apparatus of the present invention, and detects position information or density of an image. In FIG. 2, the paper surface direction is the main scanning direction of the image forming apparatus, and the direction perpendicular to the paper surface (Y direction) is the transport direction (sub-scanning direction) (X direction) of the intermediate transfer belt (recording member).

Reference numeral 31 denotes an LED light source for illuminating (image) 69a the toner image for position detection drawn on the intermediate transfer belt 61. Reference numeral 31b denotes a condensing unit that condenses a light beam from the light emitting unit 31a of the light source 31.

Reference numeral 34 denotes an illumination lens which constitutes illumination means for condensing a light beam emitted from the light source 31, and reference numeral 32 denotes light receiving means 33 which receives specularly reflected light from the intermediate transfer belt 61 and diffusely reflected light from the toner image 69a. This is an image forming lens which forms an image forming means for forming an image on a surface.

A stop 35 is provided near the imaging lens 32.

Reference numeral 27 denotes a dust-proof glass. When the intermediate transfer belt 61 is specularly reflected, the light emitting portion 31a of the light source 1 and the stop 35 are substantially conjugated by the condensing portion 31b, the illumination lens 34, and the like. (Here, “abbreviated” means that it is sufficient that the object of the present invention can be achieved even if it is not completely in an image-forming relationship.) Incidentally, when the stop 35 is in the image-forming lens 32 or when image formation is performed. When it is on the light receiving means 33 side from the lens 32, the light emitting unit 31
The aperture a and the stop 35 are made to have a substantially conjugate relationship by a part or the whole of the condenser 31b, the illumination lens 34 and the imaging lens 32.

Thus, the toner image 69 a is efficiently illuminated by the light beam from the light source 31, and the regular reflection light beam from the intermediate transfer belt 61 is efficiently incident on the light receiving unit 33.

The imaging magnification β of the light emitting section 31a on the surface of the stop 35 by the illumination lens 34 and the condensing section 31b is | β | = 5.9.

FIG. 3 shows the light receiving means 33 of the image detecting apparatus shown in FIG.
FIG. 4 is an explanatory diagram of a waveform signal obtained in FIG.

The signal V1 is a signal value when specularly reflected light from the intermediate transfer belt 61 is incident on the light receiving means.

The signal V2 is a position detection pattern (toner image)
The illumination light is scattered (not specularly reflected) by the light receiving means 33.
Is a signal value when the amount of light incident on is reduced.

According to the present embodiment, the ^S / _N ratio of the signal ( ^V1 / _V2 )
And the position information of the position detection pattern can be detected with high accuracy.

FIG. 4 shows the signal output obtained by detecting the density of the position detection pattern (toner image) as an image detection device and obtaining the light according to the density.

According to this embodiment, the density can be detected with high accuracy without the reverse development in the middle area of the image (toner image).

FIG. 5 is a sectional view of a principal part of a second embodiment of the image detecting apparatus 69 used in the image forming apparatus of the present invention.
The position information or density of the image is detected. In FIG. 5, the horizontal direction of the paper indicates the main scanning direction of the image forming apparatus, and the direction (Y direction) perpendicular to the paper surface indicates the transport direction (sub-scanning direction) (X direction) of the intermediate transfer belt (recording member).

An LED 31 illuminates a toner image (image) for position detection drawn on the intermediate transfer belt 61.
Light source. An optical element 30 integrally forms an imaging lens 32 and an illumination lens 34 made of the same material. The image forming lens 32 is a lens including a rotationally symmetric aspherical surface which forms an image forming unit for forming a regular reflection light from the toner image on a sensor (light receiving unit) 33.

The illumination lens 34 is a lens including a rotationally symmetric aspherical surface which constitutes illumination means for condensing the light beam radiated from the light source 31. Thereby, the illumination efficiency and the imaging performance are improved. Reference numeral 35 denotes an aperture provided near the imaging lens 25. The illumination lens 34 is the LED lens 3
The light-emitting portion 31a and the aperture 35 together with the first lens surface 31b, the imaging lens 32, and the aperture 35 have a substantially optically conjugate relationship.

The refracting powers of the illumination lens 34 and the imaging lens 32 may be the same or different from each other.

The illumination lens 34 and the imaging lens 32 have the same optical axis 34a, 32a in the opposite direction to the axis (surface normal) 69b perpendicular to the intermediate transfer belt 61 including the detection pattern 69a. It is inclined.

FIG. 6 shows the optical paths of light rays emitted from both ends of the light emitting section. The size of the light emitting portion 31a of the LED light beam 31 of this embodiment is 0.4 × 0.4 mm, and the size of the image of the light emitting portion formed near the stop 35 is 2.0 × 2.
0 mm, that is, the imaging magnification | β | is 5.0. The size of the stop 35 is the same as the size of the image of the light emitting portion 31a and φ
By setting the thickness to 2.0 mm, the specularly reflected light is efficiently guided to the sensor 33 while suppressing the diffused light from the toner image 69a.

Further, by increasing the imaging magnification | β |, it is possible to guide a light beam having a wider radiation angle onto the sensor.
However, in this case, even if the light emitting unit is slightly displaced from the design center, the image of the light emitting unit largely moves on the stop, so that the mounting sensitivity of the LED is increased. Therefore, imaging magnification | β
| Is preferably used in the range of 1 to 7.0.

That is, in the present invention, the imaging magnification β is preferably 1 <| β | <7, and more preferably 1.5 <| β | <6.

In the present embodiment, the illumination magnification, the imaging performance, and the detection accuracy are improved by forming the imaging lens 32, the illumination lens 34, and the aperture in this way.

FIG. 7 shows a third embodiment of the image detecting apparatus according to the present invention.
FIG.

In this embodiment, a chip type LED 7 is used as a light source.
1 is used, and the other operations are the same as those of the first and second embodiments. The imaging magnification | β | of the imaging lens 32 of the present embodiment is 1.8. Imaging magnification | β |
Is less than 1.0, a sufficient output cannot be obtained, and the detection accuracy deteriorates.

In each of the above embodiments, the stop 35 is located anywhere between the image forming lens 32 and the intermediate transfer belt 61 and the image forming lens 32 in addition to between the image forming lens 32 and the light receiving means 33. You may.

Further, the image forming means condenses the reflected light from the pattern on the intermediate conveying belt out of the light beam from the illuminating means and condenses the light on the light receiving means. Each member may be configured as a transmission type in which the transmitted light flux is collected and guided to the light receiving unit.

[0069]

According to the present invention, when an image (position detection pattern) of each color is detected, the image forming section is controlled to perform multicolor development, and the images are superimposed to obtain a color image. Image detecting apparatus and image forming apparatus capable of detecting an image (position detecting pattern) with high accuracy and easily obtaining a high-quality color image by appropriately setting the configuration of an image detecting apparatus for detecting (position detecting pattern) Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a main part of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram of a main part of Embodiment 1 of the image detection device of the present invention.

FIG. 3 is an explanatory diagram of a signal waveform when a position detection mark is read by the image detection device of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between image density and signal output in the image detection device of the present invention.

FIG. 5 is a schematic diagram of a main part of a second embodiment of the image detection device of the present invention.

FIG. 6 is a diagram illustrating an optical path according to a second embodiment of the image detection device of the present invention.

FIG. 7 is a diagram illustrating an optical path of a third embodiment of the image detection device according to the present invention.

FIG. 8 is a schematic diagram of a main part of a conventional image detection device.

FIG. 9 is an explanatory view of an optical path of a conventional image detection device.

FIG. 10 is an explanatory diagram of a signal waveform when a position detection mark of a conventional image detection device is read.

FIG. 11 is an explanatory diagram showing a relationship between image density and signal output of a conventional image detection device.

FIG. 12 is a diagram illustrating specular reflection light and toner diffusion light on a recording member.

[Explanation of symbols]

 2a to 2d photosensitive drums 1a to 1d optical scanning device 61 intermediate transfer belt 62 drive roller 63 driven roller 69 image detection device 31 light source (LED) 31a light emitting unit 31b lens surface 32 image forming lens 33 sensor 34 illumination lens 35 aperture Pa to Pd image forming unit 10 full color image forming unit 80 document reading unit 69a position detection pattern (image)

Claims (8)

[Claims] A light source for irradiating a light beam from the light source onto a recording member on which an image is formed; and a light source for forming an image on the recording member on a light receiving surface. Imaging means including an image lens, wherein the image sensing device detects an image on the recording member based on a signal obtained by the light receiving means, wherein when the recording member is a specular reflection surface, the light source means An image detecting device having an aperture at or near a position conjugate with a light emitting point. 2. The image forming apparatus according to claim 1, wherein 1 <| β | <7 is satisfied when β is an imaging magnification when the light emitting point of the light source means is imaged at its conjugate position. Image detection device. 3. The image detecting apparatus according to claim 1, wherein the aperture of the stop is substantially equal to or smaller than the size of the image of the light emitting point of the light source means. 4. An image detecting apparatus according to claim 1, wherein said stop is disposed between said image forming means and said light receiving means. 5. An image detecting apparatus according to claim 1, wherein said light receiving means detects positional information of an image formed on said recording member. 6. An image detecting apparatus according to claim 1, wherein said light receiving means detects the density of an image formed on said recording member. 7. An image forming apparatus, wherein a color image is formed by using the image detecting apparatus according to claim 1. 8. A conveying means for conveying a recording member on which an image is formed, an image forming means for forming an image on the recording member, a light source means for illuminating the image, and a light beam emitted from the light source means. An illumination unit including an illumination lens for converging light toward the image; and an imaging unit including an imaging lens for guiding reflected light from the image onto a light receiving unit surface, and obtained by the light receiving unit. In an image forming apparatus which detects position information of an image on the recording member based on a signal and obtains a color image by using the position information, when the recording member is a specular reflection surface, the light source An image forming apparatus having a stop at or near a light emitting point of the means.