JP2005300689A - Optical scanner or image forming apparatus with the optical scanner and method of optical scanning therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner or an image forming apparatus with the optical scanner in which a large swing angle is kept without lowering the resonance frequency of a mirror part which an optical deflection means has and high speed operation is possible, and to provide a method of optical scanning using them. <P>SOLUTION: The optical scanner is provide with: a light source which emits a light beam; a scanning optical system having an optical deflection means which deflects the light beam emitted from the light source; and an image carrier which is irradiated with the deflected light beam, wherein the optical deflection means is provided with: a mirror part 401 which reflects the light beam emitted from the light source; a beam which supports the mirror part 401; and a driving means which generates a rotational force on the mirror part 401. Further, the whole part or a part of the face which is directed in the same direction as the reflection face of the mirror part 401 in the optical deflection means has an optical structure (reflection structure 408) which does not reflect the light beam with which the part other than the mirror part 401 is irradiated among the light beams with which the optical deflection means is irradiated, in the reflection direction of the light beam reflected with the mirror part 401. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical scanning device including an optical deflecting unit having a structure in which a mirror unit (vibrator) supported by a beam is reciprocally oscillated with the beam as a torsional rotation axis, or an image forming apparatus including the optical scanning device. And an optical scanning method thereof.

In the optical scanning devices described in Patent Document 1 and Non-Patent Document 1, a mirror unit (vibrator) supported by two beams provided on the same straight line is provided at a position facing the mirror unit. An optical deflecting means is described which is driven by electrostatic attraction between the two electrodes and causes the mirror portion to reciprocally vibrate using two beams as torsional rotation axes. Compared with the optical scanning device with a configuration that rotates the polygon mirror with a motor, the optical scanning device equipped with this optical deflection means formed by micromachining technology has a simple structure and can be collectively formed in a semiconductor process. Miniaturization is easy and the manufacturing cost is low. In addition, since a single reflecting surface is used, there is no variation in accuracy as in an optical scanning device using a plurality of reflecting surfaces, and further, since reciprocating scanning is performed, there is an advantage that high speed can be dealt with.
JP 2002-48998 A IBM J. Res.Develop Vol.24 (1980)

  However, the light deflecting means provided in the conventional optical scanning device includes a mirror part, a beam supporting the mirror part, an outer peripheral part, a comb electrode part for driving, and an electrode pad for electrical connection with the outside. Etc. When a light beam is applied to this light deflecting means, when light having a large beam diameter such as a large-diameter light beam is irradiated, a part of the light hits the outer peripheral portion and causes reflection there. Since the reflected light at the outer peripheral portion has the same angle as the central angle of scanning of the mirror portion, the reflected light at the outer peripheral portion reaches the image carrier and becomes noise light, which causes a reduction in image quality.

  Further, if the distance between the mirror portion and the outer peripheral portion is reduced in order to reduce the light deflection means, it is necessary to sufficiently reduce the light beam diameter for the mirror portion in order to prevent light leakage to the outer peripheral portion. However, in order to reduce the light beam diameter, an expensive optical system is required, which raises the problem of increasing the cost of the apparatus.

  Therefore, since there is a limit to the reduction in the diameter of the light beam, it is general that the size of the mirror portion is sufficiently large so that the light beam can be irradiated only to the mirror portion in the conventional light deflecting means. . Therefore, there arises a problem that the deflection angle of the mirror part is reduced and the scanning speed is lowered. Therefore, conventionally, it is difficult to increase the deflection angle of the mirror portion and increase the resonance frequency, and there is a limit to the high-speed operation of the optical deflecting means.

  In view of the above-described problems, the present invention provides an optical scanning device provided with an optical deflection unit capable of operating at high speed with a large deflection angle without reducing the resonance frequency of the mirror portion provided in the optical deflection unit. An object of the present invention is to provide an image forming apparatus provided with the optical scanning device and an optical scanning method using them.

  According to a first aspect of the present invention, there is provided a light source that emits a light beam controlled based on image data, a scanning optical system that includes a light deflecting unit that deflects the light beam emitted from the light source, and the deflected light. An optical scanning device including an image carrier irradiated with a beam, wherein the light deflection unit includes a mirror unit that reflects a light beam emitted from the light source, a beam that supports the mirror unit, Drive means for generating a rotational force in the mirror part, and the mirror part is a vibrating mirror that reciprocally vibrates at a predetermined scanning frequency with the beam as an axis, and a reflection surface of the mirror part in the light deflecting means; All or a part of the surfaces facing the same direction are obtained by irradiating a portion of the light beam irradiated to the light deflecting unit other than the reflecting surface of the mirror portion with the reflecting surface of the mirror portion. Reflected light Characterized in that the optical scanning device having an optical structure which does not reflected on the reflection direction of the over arm.

  According to a second aspect of the present invention, the optical structure reflects a light beam in a direction other than the reflection direction of the light beam reflected by the reflecting surface of the mirror portion, of the light beam irradiated on the light deflection unit. 2. An optical scanning device according to claim 1, wherein the optical scanning device has a structure to be constructed.

  The invention according to claim 3 is the optical scanning device according to claim 2, wherein the optical structure comprises a reflecting mirror having a surface direction different from the reflecting surface of the mirror section.

  According to a fourth aspect of the present invention, the optical structure has a surface direction different from that of the reflective surface of the mirror portion, and the plurality of mirrors having a smaller area of the reflective surface as compared with the reflective mirror according to the third aspect. The optical scanning device according to claim 2, comprising:

  According to a fifth aspect of the present invention, in the optical structure, a groove or a hole having an aspect ratio of 1 or more is formed on all or a part of the surfaces having the same direction as the reflecting surface of the mirror portion in the light deflecting unit. 3. An optical scanning device according to claim 2, wherein the optical scanning device is formed.

  According to a sixth aspect of the present invention, the optical structure is a surface of all or a part of the surfaces having the same direction as the reflecting surface of the mirror portion in the light deflecting unit, and the light beam emitted from the light source 6. The optical scanning device according to claim 5, wherein the ratio of the opening area of the groove or hole to the non-opening area other than the groove or hole formed on the surface is 1 or more in the portion irradiated with It is characterized by that.

  According to a seventh aspect of the present invention, a light beam reflected from a portion other than the reflecting surface of the mirror portion out of the light beam emitted from the light source to the light deflecting means is shielded so as not to reach the image carrier. 7. The optical scanning device according to claim 1, wherein a means is provided.

  According to an eighth aspect of the present invention, there is provided a light shielding unit so that a light beam reflected by a portion other than the reflection surface of the mirror portion of the light beam emitted from the light source to the light deflecting unit does not reach the light source. The optical scanning device according to any one of claims 1 to 6 is provided.

  According to a ninth aspect of the present invention, the diameter of the light beam emitted from the light source irradiated on the reflecting surface of the mirror unit is larger than the reflecting surface of the mirror unit, and the light beam is irradiated on the light deflecting unit. 9. The optical scanning device according to claim 1, wherein an overfield optical system that uses only a light beam reflected by the reflecting surface of the mirror portion as effective reflected light is formed. It is characterized by.

  According to a tenth aspect of the present invention, an image forming apparatus including the optical scanning device according to the ninth aspect is provided.

  The invention according to claim 11 includes a mirror section comprising a vibrating mirror that reciprocally vibrates a light beam emitted from a light source emitting a light beam controlled based on image data at a predetermined scanning frequency about a beam. An optical scanning device for deflecting light by an optical deflecting unit and irradiating an image carrier provided in the optical scanning device or an optical scanning method for an image forming apparatus provided with the optical scanning device, wherein the optical deflecting unit includes: All or a part of the surface facing the same direction as the reflecting surface of the mirror part is a light beam irradiated to a part other than the reflecting surface of the mirror part among the light beams irradiated to the light deflecting unit. The optical scanning method is characterized in that the light beam is not reflected in the reflection direction of the light beam reflected by the reflection surface of the mirror portion.

  According to the present invention, among the light beams emitted from the light source included in the optical scanning device and controlled based on the image data, the light beams irradiated to other than the mirror unit provided in the light deflecting unit included in the optical scanning device are Since it does not reach the image carrier that is provided in the optical scanning device and is rotatably held to carry the formed image, the mirror portion can be made smaller with respect to the light beam diameter, and the resonance frequency of the mirror portion can be increased. As a result, it is possible to realize an optical deflecting unit having a large deflection angle of the mirror section and a high optical scanning speed.

  The best mode for carrying out the present invention includes a light source that emits a light beam controlled based on image data, a scanning optical system that includes a light deflection unit that deflects the light beam emitted from the light source, and In the optical scanning device including an image carrier to which the deflected light beam is irradiated, the light deflecting unit includes a mirror unit that reflects the light beam emitted from the light source, and a beam that supports the mirror unit. And a driving means for generating a rotational force in the mirror part. The mirror unit is a vibrating mirror that reciprocally vibrates at a predetermined scanning frequency with the beam as an axis, and all or a part of the surface facing the same direction as the reflecting surface of the mirror unit in the light deflection unit is An optical structure that does not reflect a light beam irradiated to a portion other than the reflection surface of the mirror unit in a reflection direction of the light beam reflected by the reflection surface of the mirror unit out of the light beam irradiated to the light deflection unit; To do.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the examples described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise described, the present invention is not limited to these examples.

  First, the schematic configuration and function of an optical scanning module provided in the optical scanning device of the present embodiment will be described below with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of an optical scanning module provided in the optical scanning device of this embodiment. FIG. 2 is a top view of the schematic configuration of the optical scanning module provided in the optical scanning device of the present embodiment. An optical scanning module 300 having the configuration shown in FIGS. 1 and 2 includes an optical deflecting unit 100 having a movable mirror portion provided with a drive circuit, a lens 101 for condensing a light beam from an LD (laser diode), and an LD. A fixed mirror 102 that guides the light beam to the light deflecting means 100, condensing lenses 103 and 104 for the light beam after optical scanning, an LD chip 106 including a drive circuit, and the like are mounted on a housing 105.

The drive circuit included in the LD chip 106 modulates the LD chip 106 according to the transmitted image data, and the LD chip 106 according to the amount of light on the back surface of the LD chip 106 detected by a monitor PD chip (not shown). The applied current is controlled to keep the light emission output constant. In the drive circuit provided in the light deflecting unit 100, a pulsed voltage having a period corresponding to the resonance frequency of the mirror provided in the light deflecting unit 100 is applied to an electrode (not shown) provided in the light deflecting unit 100. Then, the mirror part is vibrated.
In this way, the optical scanning module irradiates the image carrier 200 (photosensitive drum in the electrophotographic process) shown in FIG. 1 with the light beam corresponding to the image data.

  Next, with reference to FIG. 3, the operation principle and problems of the optical deflecting means 100 included in the optical scanning module provided in the optical scanning apparatus of this embodiment will be described. FIG. 3 is a schematic overall perspective view of the light deflecting unit 100 for explaining the operation principle of the light deflecting unit 100. The light deflection unit 100 is made of Si, and is formed of a frame 302, a beam 303, and a mirror unit 304.

The dimensions of the mirror unit 304 are 2 × a for the vertical and 2 × b for the horizontal, the length in the rotation axis direction of the beam 303 is L, the width is c, and the thickness of the mirror unit 304 is d.
When the density of Si is ρ, the mass M of the mirror unit 304 is
M = 4abρd (Equation (1))
Therefore, the moment I of the mirror part 304 is
I = (M / 3) · a2... Equation (2).
Further, the spring constant K of the mirror portion 304 is G, where the material constant of Si is G.
K = (G / 2L). {Cd (c2 + d2) / 12}... Equation (3).
Therefore, the resonance frequency f of the mirror unit 304 is
f = (1 / 2π) · (K / I) 1/2 ·············································································································

  Here, in order to realize high-speed operation of the light deflecting unit 100, the resonance frequency f can be increased by reducing the thickness d of the mirror unit 304 and reducing the mass M of the mirror unit 304 itself. However, on the other hand, the mirror part 304 is warped during driving, and it becomes difficult to obtain a parallel beam.

Conversely, when the thickness d of the mirror part 304 is increased, the rigidity of the beam 303 is increased, the touch angle θ is reduced, and the resonance frequency f is deteriorated due to an increase in the mass M. Further, since the length L of the beam 303 is proportional to the maximum deflection angle θ (the angle at which the beam 303 breaks when it is further swung), the length L of the beam is increased in order to increase the maximum deflection angle θ.
Assuming that a, b, c, and d are constant, the resonance frequency f is calculated from the equations (1) and (4) as follows:
f = (1 / 2π) · [{Gcd (c2 + d2)} / 24LI]] 1/2 = A · (1 / LI) 1/2 (where A is a constant)・ ・ ・ ・ ・ ・ Formula (5)
Since the beam length L and the maximum deflection angle θ are in a proportional relationship, the equation (5) is
f = A. (1 / I.theta.) 1/2 (where A is a constant)... (6)
Therefore, the maximum deflection angle θ is
θ = (B / I) · (1 / f2) (where B is a constant)... (7)

  Therefore, from equation (7), the maximum deflection angle θ and the resonance frequency f2 are in an inversely proportional relationship. Therefore, increasing the maximum deflection angle θ decreases the resonance frequency f. Therefore, in order to increase the deflection angle θ and increase the resonance frequency, the vertical 2 × a and horizontal 2 × b of the mirror portion should be reduced from the equations (1), (2), and (4). It is clear that is effective. However, when the size of the mirror portion is reduced, a part of the light beam emitted from the light source and applied to the deflecting means is detached from the mirror portion and is applied to the outer peripheral portion surrounding the mirror portion. Since this outer peripheral part is within the range of the deflection angle of the mirror part, the light beam applied to the outer peripheral part is reflected in the same direction as the light applied to the mirror part. For this reason, the light reflected by the outer peripheral portion becomes noise light of the optical scanning device, which degrades the optical performance of the device.

  Here, FIG. 4A is a schematic top view of the conventional light deflecting means. As shown in FIG. 4 (a), the conventional light deflecting means includes a mirror portion 401, a beam 405 that supports the mirror portion 401, an outer peripheral portion 403, a comb electrode portion 404 for driving, and an electrical connection with the outside. An electrode pad 402 is provided for taking. When a light beam is applied to the light deflecting means, when light having a large beam diameter such as a large-diameter light beam shown in FIG. 4A is irradiated, a part of the light hits the outer peripheral portion 403 and causes reflection there. Since the reflected light of the outer peripheral portion 403 is the same angle as the central angle of scanning of the mirror portion 401 (usually 0 degree), the reflected light on the outer peripheral portion 403 is an image carrier (a photoconductor in normal electrophotography). ) 200 (see FIGS. 1 and 2), it becomes noise light and causes image quality to deteriorate.

  FIG. 4B is a schematic top view of another conventional light deflector. As shown in FIG. 4B, when the distance between the mirror 401 and the outer periphery 403 is reduced to reduce the light deflection means, the light beam diameter with respect to the mirror 401 is prevented in order to prevent light leakage to the outer periphery 403. Must be sufficiently small. However, in order to reduce the light beam diameter, an expensive optical system is required, which raises the problem of increasing the cost of the apparatus. In addition, since there is a limit to reducing the diameter of the light beam, the mirror unit 401 must be enlarged. Therefore, in the conventional light deflecting means, the size of the mirror unit 401 is generally sufficiently large so that the light beam can be irradiated only to the mirror unit 401. Therefore, the deflection angle of the mirror unit 401 is reduced. And the problem of reducing the optical scanning speed occurs. Therefore, conventionally, it has been difficult to increase the deflection angle and increase the resonance frequency of the mirror unit 401. Therefore, there is a limit in operating the light deflection means at high speed.

  Next, a schematic configuration of the light deflection unit 100 (see FIGS. 1 and 2) of the present embodiment will be described with reference to FIG. FIG. 5 is a schematic top view of the light deflecting means of the present embodiment. The mirror part 401 is connected to the outer peripheral part 403 by a beam 405. A comb-tooth electrode 404 for driving the mirror section 401 is formed on the end of the mirror section 401 and the outer peripheral section 403 corresponding to the end, and an electrode pad 402 for flowing current to the comb-tooth electrode 404 is formed on the outer peripheral section 403. Is formed. The present embodiment is characterized in that reflection structures 408 to 410 are formed in a portion of the outer peripheral portion 403 excluding the electrode pad 402.

  Next, the reflection structure 408 included in the light deflecting unit 100 (see FIGS. 1 and 2) of this embodiment will be described with reference to FIGS. 6 (a) and 6 (b). FIG. 6A is a schematic top view of the light deflecting means of this embodiment. FIG. 6B is a partially enlarged perspective view of the reflecting structure included in the light deflecting unit of the present embodiment. FIG. 6B shows a partially enlarged perspective view of a portion indicated by a broken line AA ′ of the light deflecting means in the present embodiment shown in FIG. As shown in FIG. 6B, a small mirror having an angle of 45 degrees and a height of 5 μm is formed on the entire surface of the light deflection unit 100 except for the electrode pad 402 (not shown). The light deflecting unit 100 of the optical scanning device of the present embodiment is configured such that the light scanning angle of the mirror unit 401 is swung within a range of -10 degrees to +10 degrees and a width of 20 degrees.

  Next, the optical scanning angle of the optical deflecting unit 100 of this embodiment will be described with reference to FIG. FIG. 7 is a diagram for explaining the optical scanning angle of the optical deflecting unit of the present embodiment. The light beam incident on the light deflection unit 100 at an angle of 60 degrees is optically scanned at an angle between 100 degrees and 140 degrees by the mirror unit 401. On the other hand, the light beam reflected by the reflecting structures 408 to 410 of the outer peripheral portion 403 is emitted in the direction of 30 degrees. Thus, the scanning light (light beam) reflected by the mirror unit 401 and the reflected light (light beam) reflected by the outer peripheral part 403 can be separated. Regarding the manufacturing method of the light deflecting unit 100, the mirror 401, the beam 405, the comb electrode 404, and the like can be formed by, for example, a process disclosed in JP-A-2002-267996. In addition, the inclined mirror of the outer peripheral portion 403 can be formed by, for example, a method disclosed in Japanese Patent Laid-Open No. 2000-32410.

  Next, with reference to FIGS. 8A, 8B, and 8C, a light deflecting unit of another embodiment according to the present invention will be described. FIGS. 8A, 8B and 8C are diagrams for explaining the light deflecting means of the other first, second and third embodiments according to the present invention, respectively. 8A, 8 </ b> B, and 8 </ b> C, the distance between the mirror portion 401 and the outer peripheral portion 403 is narrower than that in the above-described embodiment. However, even in these cases, the reflection structure formed on the outer peripheral portion 403 can separate the reflected light of the light beam on the outer peripheral portion 403 and the reflected light of the light beam on the mirror portion 401.

  Next, with reference to FIGS. 9A and 9B, a description will be given of a first modification of the reflecting structure of the light deflecting means of the present embodiment. FIG. 9A is a schematic top view of the light deflecting means of the present embodiment. FIG. 9B is a partially enlarged perspective view of a first modification of the reflecting structure included in the light deflecting unit of the present embodiment. FIG. 9B shows a partially enlarged perspective view of the portion indicated by the broken line AA ′ of the light deflecting means in this modification shown in FIG. As shown in FIG. 9B, a small mirror having an angle of 45 degrees and a height of 5 μm is formed on the entire surface of the light deflection unit 100 except for the electrode pad 402 (not shown). The reflection surface of the reflection structure 409 provided on the outer peripheral portion 403 is rotated 90 degrees with respect to the reflection surface in the above-described embodiment. The reflection structure 409 can emit the reflected light of the light beam at the outer peripheral portion 403 in a direction perpendicular to the light scanning direction of the reflected light of the light beam at the mirror portion 401. Therefore, it is possible to obtain an effect that the reflected light of the light beam at the mirror part 401 and the reflected light of the light beam at the outer peripheral part 403 can be easily separated.

  Next, with reference to FIGS. 10A and 10B, a second modification of the reflecting structure included in the light deflecting unit 100 of this embodiment will be described. FIG. 10A is a schematic top view of the light deflecting means of the present embodiment. FIG. 10B is a partially enlarged perspective view of a second modification of the reflecting structure 408 included in the light deflecting unit of the present embodiment. FIG. 10B shows a partially enlarged perspective view of the portion indicated by the broken line AA ′ of the light deflecting means in this modification shown in FIG. As shown in FIG. 10B, a cylindrical hole having a diameter of 5 μm and a depth of 10 μm is formed on the entire surface excluding the electrode pad 402 (not shown) in the outer peripheral portion 403. The ratio of the opening area of the hole in the portion of the outer peripheral portion 403 excluding the electrode pad 402 (not shown) provided in the outer peripheral portion 403 is about 60%. The reflecting surface of the reflecting structure provided in the outer peripheral portion 403 is inside the cylindrical hole, but once the light beam has entered the cylindrical hole, multiple reflections occur inside the cylindrical hole. However, the number of light beams emitted from the opening of the cylindrical hole in an irregular direction and emitted in the same direction as the reflected light of the light beam reflected by the mirror portion is very small. In addition, since the reflecting structure 410 has a high effect of uniformly scattering the light beam regardless of the direction of the light beam incident on the outer peripheral portion 403, there is no direction dependency due to the structure, and optical handling is easy.

  Next, the overfield using the light deflecting means 100 according to the present embodiment will be described with reference to FIG. FIG. 11 shows an example of an overfield using the light deflecting means according to this embodiment. The light beam 411 incident on the light deflecting means shown in FIG. 11 may be a large-diameter light beam 411 including the mirror portion 401 as indicated by a dotted line in FIG. According to the present embodiment, of the large-diameter light beam 411, only the portion irradiated on the mirror portion becomes the writing light that reaches the image carrier 200 (see FIGS. 1 and 2) after reflection, The optical system can be configured so that the light beam reflected by the outer peripheral portion 403 that may cause other noise does not reach the image carrier 200. As a result, the writing beam diameter can be defined not by the beam diameter incident on the light deflecting means 100 but by the size of the mirror unit 401, which is effective in reducing the writing beam diameter. Further, since the size of the mirror unit 401 is not regulated by the beam diameter incident on the light deflecting unit 100, the mirror unit 401 can be reduced in size, and the deflection angle of the mirror unit 401 can be increased and the optical scanning speed can be improved. It is possible to achieve both.

  Next, the configuration and function of the image forming apparatus to which this embodiment is applied will be described below with reference to FIG. As shown in FIG. 12, this image forming apparatus is supplied from an external device via, for example, a copying function for copying a document image, a facsimile function for transmitting / receiving image data via a communication line, and an external I / F. An image forming apparatus having a printer function for printing based on image data, that is, a composite digital image forming apparatus (hereinafter abbreviated as an image forming apparatus) is configured.

  FIG. 12 is a sectional view schematically showing the internal structure of the image forming apparatus. As shown in FIG. 12, an image forming apparatus to which the present embodiment is applied, for example, an electrophotographic digital image forming apparatus 50, includes an image reading unit that functions as a reading unit that reads a document image and generates image data. That is, it has a scanner unit 50a and an image forming unit that functions as an image forming unit that forms an image based on image data, that is, a printer unit 50b. Further, the image forming apparatus 50 includes an automatic document feeder 51 as a conveying unit above the scanner unit 50a. The image forming apparatus 50 is formed so as to be openable and closable with respect to a later-described document table or document table of the scanner unit 50a. The document D as an object is fed one by one toward the document table, and functions as a document pressing unit that brings the document D placed on the document table into close contact with the document table.

  The scanner unit 50 a is disposed at the top of the document table 52 made of transparent glass, facing the automatic document feeder 51 in a closed state and on which the document D is set, and one end of the document table 52. A document scale 53 indicating the position where the document D should be set on the document table 52 is also provided.

  Below the document table 52, an exposure lamp 54 that illuminates the document D placed on the document table 52, an auxiliary reflector 58 for condensing the light beam from the exposure lamp 54 on the document D, and the document D A first mirror 56 that bends the reflected beam from the left side in the figure is arranged. The exposure lamp 54, the auxiliary reflecting plate 58, and the first mirror 56 are fixed to the first carriage 57, and are arranged to be movable in parallel with the document table 52 as the first carriage 57 moves. The first carriage 57 is moved in parallel along the document table 52 by receiving a driving force of a pulse motor (not shown) via a toothed belt (not shown).

  A second carriage 59 is disposed on the left side of the document table 52 in the drawing, that is, in the direction in which the reflected beam reflected by the first mirror 56 is guided. In the second carriage 59, a second mirror 60 for bending the reflected beam from the document D guided by the first mirror 56 downward and a third mirror 61 for bending rightward in the drawing are arranged at right angles to each other. The second carriage 59 is driven by the first carriage 57 by a toothed belt (not shown) that drives the first carriage 57 and parallel to the first carriage 57 along the document table 52 at a speed of 1/2. Moved to.

  An imaging lens that forms an image of the reflected beam from the second carriage 59 at a predetermined magnification in a plane below the first carriage 57 and including the optical axis of the beam folded back through the second carriage 59. 62, and a line sensor 63 including a plurality of CCD image sensors for converting the reflected beam, which is focused by the imaging lens 62, into an electrical signal, that is, image data.

  Here, the direction in which the plurality of CCD image sensors in the line sensor 63 are arranged is the main scanning direction, and the direction in which the first carriage 57 and the second carriage 59 move is the sub-scanning direction. In the present embodiment, the reading device portion is a sheet-through type image reading system in which the scanner unit 50a is fixed and the automatic document feeder 51 reads an image while conveying the document.

  Next, the printer unit 50b will be described. The printer unit 50 b includes a photosensitive drum 12, a charging charger 13, developing units 14 and 15, a static elimination lamp (PTL) 17, a transfer charger 18, a separation charger 19, an eraser 20, a cleaning unit 21, It has a polygon mirror (laser light generator) 22 and an optical system (lens) 23, and performs image formation and output of image data stored in an image memory.

  That is, at the same time as the photosensitive drum 12 is rotated in the direction of the arrow, the residual toner and non-uniform potential adhering to the photosensitive drum 12 do not reach the charging charger 13 and the developing units 14 and 15, so QL) 16, a pre-transfer static elimination lamp (PTL) 17, a transfer charger 18, a separation charger 19, an eraser 20, and a cleaning unit 21, and the surface potential of the photosensitive drum 12 after passing through the static elimination lamp 16 is substantially equal. Try to be zero.

  Thereafter, the surface of the photosensitive drum 12 is uniformly charged by the charging charger 13, the image data stored in the image memory is read, and a laser beam is emitted from a semiconductor laser (not shown) accordingly. Laser light emitted from the semiconductor laser is incident on a polygon mirror (laser light generator) 22 that is condensed and rotated by a cylinder lens (not shown), and reflected light passes through an optical system (lens) 23 and a mirror 24. The surface of the photosensitive drum 12 is irradiated to form an electrostatic latent image.

  Next, the latent image formed on the photosensitive drum 12 is subjected to development with black toner after the charge of the non-image portion (unnecessary portion protruding from the image forming area) is removed by the eraser 20 or with the black toner. The color developing unit 15 that performs development with toner attaches toner to form a visible image. At this time, the density of the image can be adjusted by changing the developing bias potential.

  On the other hand, one of the calling roller 25 and the three paper supply rollers 26 is driven by turning on a paper supply clutch that can selectively take out the drive of a main motor (not shown) to a preselected paper supply stage (described later). The set recording paper is fed toward the stopped registration roller pair 27. A registration sensor 28 is disposed in front of the registration roller pair 27. The registration sensor 28 is, for example, a reflection type photosensor, and is turned on when the leading edge of the recording paper reaches the opposite position. Then, after a predetermined time has elapsed, the paper feeding clutch is returned to the OFF state, and the recording paper being conveyed is stopped.

  The timing for turning off the paper feed clutch is set longer than the time during which the recording paper is conveyed between the registration sensor 28 and the registration roller pair 27. Accordingly, the leading edge of the recording paper is abutted against the pair of registration rollers 27, and the recording paper stands by in a state where the leading edge is bent to prevent skew and the like. Thereafter, the registration clutch is turned on at a timing in accordance with the leading edge of the image on the photosensitive drum 12, and the registration roller pair 27 is driven to rotate, whereby the standby recording paper is conveyed again toward the transfer unit. .

  When the recording paper reaches the transfer portion, the toner image on the photosensitive drum 12 is transferred onto the paper surface by the action of the transfer charger 18, and then on the paper surface by the action of the separation charger 19 held integrally with the transfer charger 18. Then, the recording paper is separated from the surface of the photosensitive member by the separation claw 29.

  Next, the recording paper is fed to the fixing unit by the conveying belt 30 stretched by two rollers, and the toner image is thermally fixed by the fixing roller 31. After that, if the single-side mode is selected as the copy mode, the switching claw 32 By switching, the sheet is fed into the lower sheet refeeding conveyance path 33.

  The residual toner on the photosensitive drum 12 after the image transfer is removed by the cleaning brush 21a and the cleaning blade 21b constituting the cleaning unit 21 and recovered in the toner recovery tank 21c. The surface is exposed to the front by the charge eliminating lamp 16.

  By the way, this copying machine is equipped with three paper feed cassettes 34 to 36, each of which has a different size of recording paper, detachably attached as a normal paper feed cassette that can store only recording papers of a specific size. Also provided is a manual feed table (manual feed tray) 37 on which recording paper that is not stored in any paper feed cassette, that is, recording paper of an unspecified size can be set.

  When copying using recording paper stored in any of the paper cassettes 34 to 36, the cassette size is selected by a size selection key on an operation panel (not shown), and then the copy start key is pressed. Thus, the recording paper is fed from the paper feed cassette.

  Reference numerals 38a to 38c are size detection sensors for detecting the size of each storage sheet of each of the paper feed cassettes 34 to 36, and for example, five photo interrupters are used. In addition, a light-shielding plate for size identification (not shown) is attached to the front end of each of the paper feed cassettes 34 to 36. The light shielding plate has a notch that varies depending on the size of the recording paper to be stored in the cassette.

  When the paper feed cassettes 34 to 36 are mounted, the size detection sensors 38a to 38c are configured so that only the photo interrupter sandwiching the light shielding portion of the light shielding plate blocks the optical path. Can be output. The control unit is a CPU or the like. On the other hand, when copying using recording paper of an unspecified size, the manual feed table 37 is opened from the closed state indicated by the phantom line in the direction indicated by arrow A to the use state indicated by the solid line, and then the desired surface is displayed on the upper surface. By setting the recording paper and pressing the copy start key, the recording paper is fed from the manual feed table 37.

  When the manual feed table 37 is rotated in the opening direction, the bottom plate raising arm 39 that has lifted the recording paper placement bottom plate provided in the first paper feed cassette 34 is lowered in conjunction therewith. An open / close detection sensor (not shown) for detecting opening / closing of the manual feed table 37 is installed at a position facing the manual feed table 37 of the copying machine.

It is a schematic structure sectional view of the optical scanning module provided in the optical scanning device of this example. It is a schematic configuration top view of an optical scanning module provided in the optical scanning device of the present embodiment. It is a schematic whole perspective view of the optical deflection | deviation means of a present Example. (A) is a schematic top view of the conventional light deflection means. (B) is another schematic top view of the conventional light deflection means. It is a schematic configuration top view of the light deflecting means of the present embodiment. (A) It is a schematic top view of the light deflection | deviation means of a present Example. (B) is the elements on larger scale of the reflective structure which the optical deflection | deviation means of a present Example has. It is a figure for demonstrating the optical scanning angle of the optical deflection | deviation means of a present Example. (A) is a figure for demonstrating the optical deflection | deviation means of the other 1st Example by this invention. (B) is a figure for demonstrating the optical deflection | deviation means of the other 2nd Example by this invention. (C) is a figure for demonstrating the optical deflection | deviation means of the other 3rd Example by this invention. (A) It is a schematic top view of the light deflection | deviation means of a present Example. (B) is the elements on larger scale of the 1st modification of the reflective structure which the optical deflection | deviation means of a present Example has. (A) It is a schematic top view of the light deflection | deviation means of a present Example. (B) is the elements on larger scale of the 2nd modification of the reflection structure which the optical deflection | deviation means of a present Example has. It is a figure which shows the example of the over field using the optical deflection | deviation means by a present Example. 1 is a cross-sectional view schematically showing an internal structure of an image forming apparatus to which an embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Light deflection | deviation means 101 Condensing lens 102 Fixed mirror 103 Condensing lens 104 Condensing lens 105 Case 106 LD chip 200 Image carrier 300 Optical scanning module 302 Frame 303 Beam 304 Mirror part 401 Mirror part 402 Electrode pad 403 Outer peripheral part 404 Comb electrode portion 405 Beam 406 Large aperture light beam 407 Small aperture light beam 408 Reflective structure (optical structure)
409 Reflective structure (optical structure)
410 Reflective structure (optical structure)
411 Light beam

Claims (11)

A light source that emits a light beam controlled based on image data;
A scanning optical system having light deflecting means for deflecting the light beam emitted from the light source;
An optical scanning device comprising an image carrier to which the deflected light beam is irradiated,
The light deflecting unit includes a mirror unit that reflects a light beam emitted from the light source, a beam that supports the mirror unit, and a driving unit that generates a rotational force on the mirror unit.
The mirror unit is a vibrating mirror that reciprocally vibrates at a predetermined scanning frequency with the beam as an axis,
All or a part of the surface of the light deflection unit facing the same direction as the reflection surface of the mirror unit is irradiated to a portion other than the reflection surface of the mirror unit of the light beam irradiated to the light deflection unit. An optical scanning device comprising: an optical structure that does not reflect the light beam to be reflected in the reflection direction of the light beam reflected by the reflecting surface of the mirror portion.   The optical structure is a structure that reflects a light beam in a direction other than a reflection direction of a light beam reflected by a reflection surface of the mirror portion, among light beams irradiated on the light deflecting unit. The optical scanning device according to claim 1.   The optical scanning device according to claim 2, wherein the optical structure includes a reflection mirror having a surface direction different from a reflection surface of the mirror unit.   The said optical structure consists of a some mirror with the area of the reflective surface small compared with the said reflective mirror of Claim 3 which has a surface direction different from the reflective surface of the said mirror part. Item 3. The optical scanning device according to Item 2.   In the optical structure, a groove or a hole having an aspect ratio of 1 or more is formed on all or a part of the surfaces having the same direction as the reflecting surface of the mirror portion in the light deflecting unit. 3. The optical scanning device according to claim 2, wherein:   The optical structure is a part or all of a surface having the same direction as the reflecting surface of the mirror portion in the light deflecting unit, and in the portion irradiated with the light beam emitted from the light source, 6. The optical scanning device according to claim 5, wherein a ratio of an opening area of the groove or hole to a non-opening area other than the groove or hole formed on the surface is 1 or more.   Among the light beams emitted from the light source to the light deflection means, a light shielding means is provided so that a light beam reflected by a portion other than the reflection surface of the mirror portion does not reach the image carrier. The optical scanning device according to any one of claims 1 to 6.   The light-shielding means is provided so that the light beam reflected by parts other than the reflective surface of the mirror part among the light beams emitted from the light source to the light deflecting means does not reach the light source. Item 7. The optical scanning device according to any one of Items 1 to 6.   The diameter of the light beam emitted from the light source irradiated on the reflecting surface of the mirror unit is larger than the reflecting surface of the mirror unit, and the light beam irradiated on the light deflecting unit is reflected by the reflecting surface of the mirror unit. 9. The optical scanning device according to claim 1, wherein an overfield optical system that uses only the reflected light beam as effective reflected light is formed.   An image forming apparatus comprising the optical scanning device according to claim 9. A light beam emitted from a light source that emits a light beam controlled on the basis of image data is deflected by a light deflecting unit including a mirror part that includes a vibrating mirror that reciprocally vibrates at a predetermined scanning frequency about a beam. An optical scanning device for irradiating an image carrier provided in the optical scanning device, or an optical scanning method for an image forming apparatus provided with the optical scanning device,
All or part of the surface of the light deflecting unit facing the same direction as the reflecting surface of the mirror unit is irradiated to a portion other than the reflecting surface of the mirror unit in the light beam irradiated to the light deflecting unit. An optical scanning method characterized by not reflecting the light beam to be reflected in the reflection direction of the light beam reflected by the reflecting surface of the mirror section.

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