JP2010133999A - Optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner in which a plurality of light beam detection means are simply disposed at appropriate positions and to provide an image forming apparatus using the optical scanner. <P>SOLUTION: The optical scanner includes: a detection means fixing member 142 which disposes synchronization detection sensors 140, 141 at other than an image forming region in a reciprocal scanning region of a light beam from an oscillation mirror 106 and fixes the synchronization detection sensors 140, 141 so that the light receiving surfaces of the synchronization detection sensors 140, 141 may have a desired distance between them; and a housing body 250 having a positioning part for arranging the detection means fixing member 142 and a scanning lens 120 in a predetermined arrangement relationship with respect to the center line of the amplitude of the reciprocal scanning of the light beam using the oscillation mirror 106. The detection means fixing member 142 and the scanning lens 120 are positioned and fixed at the positioning part of the housing body 250 by positioning means 145, 146. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical scanning device that scans a surface to be scanned with a light beam emitted from a light emitting unit, and a light amount control for detecting synchronization detection by selecting the light beam in a synchronization detection unit of the optical scanning device, The present invention relates to an image forming apparatus using an optical scanning device.

  In a conventional optical scanning device, a polygon mirror or a galvanometer mirror is used as a deflector that scans a light beam. In order to achieve a higher resolution image and high-speed printing, this rotation must be further increased, and a bearing is used. Durability, heat generation due to wind damage, and noise are issues, and there is a limit to high-speed scanning.

  In contrast, in recent years, research on deflection devices using silicon micromachining has been underway, and as disclosed in Patent Document 1 and Patent Document 2, an oscillating mirror and a torsion beam that pivotally supports it are integrally formed on a Si substrate. This method (MEMS (Micro Electro Mechanical Systems) vibrating mirror (or vibrating mirror)) has been proposed.

According to this method, there is an advantage that the mirror surface size can be reduced and the size can be reduced, and since reciprocal vibration is performed using resonance, high speed operation is possible but low noise and low power consumption are possible.
In addition, the housing that houses the optical scanning device can be thinned due to low vibration and almost no heat generation, and even if low-cost resin molding material with a low glass fiber content is used, the image quality is affected. There is also an advantage that it is difficult.

  Patent Documents 3 and 4 disclose examples of an optical scanning device in which a vibrating mirror is provided instead of a polygon mirror.

By using a vibration mirror instead of a polygon mirror, noise and power consumption can be reduced, and an image forming apparatus suitable for an office environment can be provided.
In addition, the housing can be made thinner as the vibration is reduced, and the weight and cost can be reduced.

  Here, in the vibrating mirror, there is a problem that the deflection angle changes due to a change in the spring constant of the torsion beam depending on the temperature or a change in the viscous resistance of air due to atmospheric pressure.

  Therefore, as disclosed in Patent Document 5, the deflection angle is detected by detecting the beam scanned by the synchronization detection sensor and the end detection sensor, and the deflection angle is adjusted by adjusting the applied current to the vibrating mirror. Control to keep stable is performed.

  Patent Documents 6 and 7 disclose a light beam characteristic evaluation method and an evaluation apparatus that can evaluate the depth of each characteristic required for a light beam.

  By the way, in order to cope with further increase in speed and color, the image forming apparatus employs a multi-beam method in which writing is performed by simultaneously scanning a plurality of light beams on one image carrier.

When performing reciprocating scanning writing with the MEMS vibrating mirror here, the scanning beam is scanned from the center of the amplitude to the outside through the light beam detecting means provided outside the image forming area, passes through the detection surface, and reaches the peak of the amplitude. The light beam is scanned in the opposite direction and again passes over the detection surface.
Therefore, unlike the case where a polygon is used for the conventional deflecting means, the light receiving surface of the light beam detecting means is traversed in the opposite direction in forward scanning and sub scanning, and the light beams at both ends from the center of the deflection angle of the light beam. Unless the light receiving surfaces of the detecting means are arranged at equal distances, the image heights for detecting the passage of the light beam are different at both ends.

  For example, when synchronous detection of PD + and PD− is installed as light beam detection means at the deflection angles θs on both sides in the main scanning direction outside the image area, the forward scanning by the reciprocating scanning that passes the image height 0 in the reciprocating scanning. The time and the backward scanning time each measure a section shifted in the image height direction by the amount of the light receiving surface position shift in the direction opposite to the traveling direction.

  When fixing the light beam detection means when adjusting the attitude of the vibrating mirror, adjusting the writing start position, and adjusting the writing conditions (pixel pitch, image frequency, etc.) for each reciprocating scan based on this detection data The position error in the main scanning direction is doubled at both ends.

Japanese Patent No. 2924200 Japanese Patent No. 30111144 Japanese Patent No. 3445691 Japanese Patent No. 3543473 JP 2004-279947 A Japanese Patent Laid-Open No. 2000-9589 Japanese Patent No. 3594813

  The present invention has been made in view of the above problems in the prior art, and uses an optical scanning device capable of easily arranging a plurality of light beam detection means at appropriate positions, and the optical scanning device. An object is to provide an image forming apparatus.

The present invention provided to solve the above problems is as follows.
[1] Light source means for emitting a light beam, light source driving means for modulating and driving the light source means, deflecting means for deflecting the light beam emitted from the light source means by a vibrating mirror and reciprocatingly scanning in the main scanning direction A deflection control means for controlling the driving of the oscillating mirror in the deflection means, a scanning imaging optical system for guiding the light beam from the deflection means onto the surface to be scanned, and the passage of the light beam from the deflection means. The plurality of light beam detecting means and the plurality of light beam detecting means are arranged outside the image forming area in the reciprocating scanning area of the light beam from the deflecting means, and the light receiving surfaces of the plurality of light beam detecting means are An optical scanning device comprising: a detection means fixing member that fixes the gap to a desired interval.
[2] A housing having a positioning portion for bringing the detection means fixing member and the scanning imaging optical system into a predetermined arrangement relationship with respect to the center line of the amplitude of the reciprocating scanning of the light beam by the deflection means, The optical scanning device according to [1], wherein the optical element of any one of the means fixing member and the scanning imaging optical system is positioned and fixed by the positioning unit of the housing by positioning means respectively provided.
[3] The optical scanning device according to [2], wherein an optical element having the largest optical power in the main scanning direction of the scanning imaging optical system includes the positioning unit.
[4] The detection means fixing member has a positioning means at an intermediate point between light receiving surfaces of the plurality of light beam detection means, and any one of the optical elements of the scanning imaging optical system has a center in the main scanning direction. The optical scanning device according to [2] or [3], wherein a positioning unit is provided in the part.
[5] The detection means fixing member is positioned on the housing such that an intermediate point between the light receiving surfaces of the plurality of light beam detection means is positioned on the center line of the amplitude of reciprocal scanning of the light beam by the deflection means. The optical scanning device according to any one of [1] to [4].
[6] The optical element of any one of the scanning imaging optical systems is positioned on the housing so that the optical axis of the optical element coincides with the center line of the amplitude of reciprocal scanning of the light beam by the deflecting unit. The optical scanning device according to any one of [1] to [5].
[7] The distance between the light receiving surfaces of the plurality of light beam detecting means is 2 * Hs, and the positional deviation in the main scanning direction of the light receiving surface of any one of the plurality of light beam detecting means is ΔH. The optical scanning device according to any one of [1] to [6], wherein ΔH / (2 × Hs) × 100 ≦ 0.01.
[8] The deflection control means controls the deflection means so that the maximum amplitude of the light beam obtained based on the detection signal detected by the light beam detection means becomes constant, and the light beam detection means detects Controlling the deflection means so as to correct the shift amount of the amplitude center of the light beam obtained based on the detected signal, and scanning the light beam obtained based on the detection signal detected by the light beam detecting means. The optical scanning device according to any one of [1] to [7], wherein one or two or more controls selected from controlling the deflecting unit so as to correct a frequency variation are executed.
[9] At least one image carrier and the optical scanning device according to any one of [1] to [8], wherein the image carrier scans light including image information. And an image forming apparatus.

According to the optical scanning device of the present invention (the invention according to claim 1), the plurality of light beam detection means (synchronization detection sensors) are fixed to the detection means fixing member in advance so that the light receiving surfaces are at a desired interval. Therefore, it is possible to reduce misalignment errors (amount of misalignment accumulated by the number of light beam detecting means) caused by individually adjusting the positions of a plurality of light beam detecting means, thereby reducing adjustment work in the mounting process and simplifying it. It is. Further, it is possible to eliminate the timing error of the passage of the light beam due to the positional deviation of the light beam detecting means itself, and it is possible to appropriately control the deflection angle of the vibrating mirror based on the synchronization detection signal of the light beam detecting means.
In addition, by fixing the detection means fixing member on which the light beam detection means is disposed to the housing with an adhesive material or the like, the predetermined relationship between the vibration mirror and the optical element is maintained while maintaining the positional relationship between the light beam detection means. Can be easily done. Furthermore, even if expansion and contraction due to environmental fluctuations occur, the position of each light beam detecting means is maintained in a predetermined positional relationship, and the vibrating mirror is appropriately set based on the detection signal that the light beam passes through the light beam detecting means. Can be controlled.

According to the invention of claim 2, the detecting means fixing member is positioned by the positioning means of the detecting means fixing member and the positioning portion of the housing, and the positioning means of the optical element of the scanning imaging optical system and the housing By positioning and fixing the optical element by the positioning unit, the optical axis of the light beam detecting means and the optical element is in a predetermined positional relationship with respect to the center line of the amplitude of the reciprocating scanning of the light beam by the deflecting means. Therefore, the swing angle control of the vibrating mirror based on the synchronization detection signal of the light beam detecting means can be performed more appropriately. This also simplifies the adjustment process of the positional relationship between the amplitude center of the light beam and the light beam detecting means.
In addition, by integrally fixing the positioning means of the detection means fixing member and the positioning portion of the housing with an adhesive layer or a fixing member such as a leaf spring or a screw, the detection means fixing member is deformed (expanded or contracted) due to environmental fluctuations. Even if (expansion etc.) occurs, the distance (swing angle) from the rotation center of the vibrating mirror to each light receiving surface is kept equal, and the timing at which the light beam passes through each light receiving surface changes equally. The vibration state of the deflecting means can be appropriately controlled based on the timing detection data.

  According to the invention of claim 3, the optical element having the largest optical power in the main scanning direction in the scanning imaging optical system has the positioning means, so that the optical element due to environmental fluctuations (temperature and humidity). When the expansion / contraction occurs, the optical element having the greatest influence, the detection means fixing member, and the light beam detection means can maintain a predetermined arrangement relationship by the positioning means. In addition, when the positioning member is in the center of the optical element, even if the optical element expands or contracts, the position layout is symmetrical with respect to the center fixed by the positioning member for the optical element. Therefore, it is possible to make an appropriate detection signal for the light beam to pass through the light receiving surface of the light beam detecting means.

According to the invention of claim 4, the detecting means fixing member uses positioning means provided at an intermediate point between the light receiving surfaces of the plurality of light beam detecting means, and any one of the optical elements of the scanning imaging optical system Using positioning means provided in the central part in the main scanning direction, each positioning means is positioned and attached to the positioning part of the housing, for example, in the detecting means fixing member, the positioning means at the center point between the light receiving surfaces is fixed to the adhesive layer or fixed When fixed by a member, even when the detection means fixing member expands or contracts due to temperature, humidity, or the like, the light receiving surfaces at both ends can maintain symmetry with respect to the fixed portion. Thereby, the timing of detecting the light beam passing through the light beam detection means is the detection of the light beam placed at the same distance between one end (+ side) and the other end (− side) of the detection means fixing member. The means can be changed in the same tendency so as not to be offset.
Further, even if the position of the light receiving surface in the light beam detecting means has individual differences, the light receiving surfaces are in a desired positional relationship via the detecting means fixing member with reference to the light receiving surface in the light beam detecting means in advance. By fixing the detection means fixing member to the center of amplitude of the light beam by fixing the detection means to the detection means fixing member on the optical axis of the optical element solidified in the housing by the positioning means at the center of the optical element. Further, an intermediate point between the light receiving surfaces of the light beam detecting means can be provided. As a result, the mounting position of the light beam detecting means within the substrate and the manufacturing error of the light receiving surface itself can be corrected and integrated with the optical scanning device via the detecting means fixing member.

According to a fifth aspect of the present invention, the detection means fixing member is arranged such that an intermediate point between the light receiving surfaces of the plurality of light beam detection means is positioned on the center line of the amplitude of reciprocal scanning of the light beam by the deflection means. Therefore, the left and right light-receiving surfaces can be deflected and scanned from the rotation center of the oscillating mirror in the deflecting means to the light-receiving surfaces of the light beam detecting means at the left and right ends. The timing at which the light beam passes can be adjusted.
According to the invention of claim 6, any one of the optical elements of the scanning imaging optical system is arranged such that the optical axis of the optical element coincides with the center line of the amplitude of reciprocal scanning of the light beam by the deflecting means. Since it is positioned in the housing, the light receiving surfaces of the light beam detecting means at both ends can be fixed at the same distance (equal deflection angle) from the optical axis of the optical element.

  According to the invention of claim 7, the distance between the light receiving surfaces of the plurality of light beam detecting means is 2 * Hs, and the main scanning of the light receiving surface of any one of the plurality of light beam detecting means is performed. When the positional misalignment in the direction is ΔH, by satisfying ΔH / (2 × Hs) × 100 ≦ 0.01, the misalignment error (the misalignment amount) with respect to the distance between the light receiving surfaces of the light beam detecting means is 0. Therefore, the detection signal can be accurately detected at a level where there is no problem with the image quality, and more in the image forming area provided inside the position of the light beam detecting means that is the synchronization detection position. Since the positional deviation is small, it is possible to achieve an image deviation within an allowable limit of 0.01% of jaggies, and it is possible to realize a high-quality image in which jaggies (jagged lines) are not noticeable.

According to the eighth aspect of the invention, since the light receiving surface of the light beam detecting means is integrally fixed via the detecting means fixing member, the distance between the light receiving surfaces is always equal, and the optical scanning device is installed. Even when the maximum amplitude of the light beam changes due to environmental fluctuations (for example, when the disturbance of the vibrating mirror or the fluctuation of the maximum deflection angle due to continuous driving occurs), the timing of the detection signal of the light beam that is detected appropriately The amplitude state can be accurately calculated from the deviation amount, the correction amount for making the maximum amplitude constant can be calculated, the deflection means can be controlled to obtain the desired maximum amplitude, and a stable light beam is scanned. Therefore, a high quality image can be formed on the image carrier.
In addition, since the light receiving surface of the light beam detection means is integrally fixed via the detection means fixing member, when the center of amplitude of the light beam is shifted due to the environmental change where the optical scanning device is installed, the light beam The amplitude state can be calculated appropriately from the timing deviation of the detection signal, the correction amount for the shift amount from the conventional amplitude center can be calculated, the deflection means can be controlled appropriately, and a high-quality image can be obtained. It can be formed on an image carrier.
In addition, since the light receiving surface of the light beam detecting means is integrally fixed via the detecting means fixing member, when the scanning frequency of the light beam fluctuates due to environmental changes in which the optical scanning device is installed (for example, a vibrating mirror) When the scanning frequency fluctuates due to disturbance or continuous driving), the applied voltage for appropriately correcting the scanning frequency can be calculated from the timing deviation of the detection signal of the light beam, and the deflection means is controlled appropriately. And a high-quality image of the semiconductor laser can be formed on the image carrier.
Furthermore, the desired scanning state of the light beam can be maintained by appropriately combining the control of the three types of deflection means.

  According to the ninth aspect of the present invention, the image forming apparatus using the optical scanning device according to any one of the first to eighth aspects fixes the light beam detection means via the detection means fixing member, thereby It is possible to improve the positional accuracy of the beam detecting means and simplify the mounting process. Even if temperature fluctuations occur, each light beam detection means is fixed by the same member (detection means fixing member), so it expands and contracts at the same rate, so the distance from the rotation center axis of the vibrating mirror to the light receiving surface Are always at equal distances. As a result, it is possible to detect the passage of the light beam with suppressed positional deviation, and it is possible to form a higher-definition output image. In addition, by suppressing the amount of synchronization detection displacement detected by the light beam detection means, it is possible to provide a high-quality image in which vertical line fluctuations such as jaggy are suppressed.

  In the optical scanning device, if the light beam detecting means (synchronous detection sensor) related to the synchronous detection of the light beam reciprocally scanned in the main scanning direction by the vibrating mirror is individually attached to the housing, the respective position error occurs. In addition, the positional layout relationship between the light receiving surfaces of the light beam detecting means also varies due to the positional deviation of the respective fixed portions.

  Therefore, the optical scanning device according to the present invention performs main scanning by deflecting the light beam emitted from the light source means for emitting the light beam, the light source driving means for modulating and driving the light source means, and the light source means by the vibrating mirror. A deflection means for reciprocating scanning in a direction, a deflection control means for controlling driving of a vibrating mirror in the deflection means, a scanning imaging optical system for guiding a light beam from the deflection means onto a scanned surface, and the deflection means A plurality of light beam detecting means for detecting the passage of the light beam, and the plurality of light beam detecting means are arranged outside the image forming area in the reciprocating scanning area of the light beam from the deflecting means, and the plurality of light beams And a detection means fixing member for fixing the light receiving surfaces of the beam detection means so as to have a desired interval. At this time, the detection means includes a housing having a positioning portion for bringing the detection means fixing member and the scanning imaging optical system into a predetermined arrangement relationship with respect to the center line of the amplitude of the reciprocating scanning of the light beam by the deflection means It is preferable that any one of the optical element of the means fixing member and the scanning imaging optical system is positioned and fixed by the positioning portion of the housing by positioning means each having.

  Here, the position layout of the light receiving surface of the light beam detecting means is uniquely determined by fixing it to the detecting means fixing member, and the positioning means of the detecting means fixing member and the positioning means of each optical element are positioned in the housing. By adjusting the positions of the light beam detecting means and fixing them to each other, the intermediate point between the light receiving surfaces of the light beam detecting means is on the amplitude center line of the light beam by the deflecting means, and the optical axis of each optical element of the scanning imaging optical system Can be fixed to fit.

  Thereby, the center position of each optical element can be adjusted while maintaining the interval between the light receiving portions. In other words, when the light beam passes through the light beam detection means (synchronization detection sensor), reaches the maximum amplitude, and passes again through the light beam detection means, the light beam detection means on the housing is displaced by the positional deviation of the light beam detection means. The difference in the image height of the light beam detection means and the image height side light beam detection means, and the difference in the image height of the light beam entering the light receiving surface of the synchronous detection sensor, is previously set as the detection means fixing member. By fixing the light beam detection means, it is possible to perform mounting adjustment in a batch through the detection means fixing member while the positional relationship of the light beam detection means is uniquely determined.

  At this time, by fixing the light receiving surface of the light beam detecting means integrally through the detecting means fixing member, the distance between the light receiving surfaces becomes constant, so that a positional deviation amount through the detecting means fixing member is generated about 10 μm. Even in this case, the jaggy is 0.00875%, which satisfies the ideal jaggy (jagged line) condition and can realize a high-quality image.

  By using a vibrating mirror supported by a torsion beam as a deflecting means, low noise, low heat generation, and low power consumption can be realized as compared with a deflecting means using a conventional polygon scanner. Image degradation due to temperature change of the optical element due to heat generation from the motor can be solved, and a more accurate drawn image can be realized. Further, the deflecting means that performs such sinusoidal vibration can be manufactured by a semiconductor process such as silicon crystal, and theoretically has no metal fatigue and is excellent in durability.

Hereinafter, an optical scanning device and an image forming apparatus according to the present invention will be described with reference to the drawings.
First, as an embodiment of the present invention, a reciprocatingly scanned light beam is formed by using a member between the light receiving surfaces of one light beam detecting means (+ image height) and the other light beam detecting means (−image height). Image forming apparatus using an optical scanning device in which a detection position shift is suppressed by a light beam detection unit integrally fixed so that a center point between light receiving surfaces is positioned on an amplitude center line of a light beam by a deflection unit An example will be described with reference to the drawings.

  FIG. 1 shows an outline of an image forming apparatus of a system (single-side scanning system) in which four stations (latent image forming stations for each color) are scanned by a single vibrating mirror 106 as a configuration example of an image forming apparatus according to the present invention. FIG. As shown in the figure, the optical scanning device that scans each photosensitive drum (image carrier) is integrally configured, and four photosensitive members are arranged at equal intervals along the moving direction of the intermediate transfer belt 105 as a transfer member. At the same time, the light beams from the light source units (light source means) 107 and 108 corresponding to the drums 101, 102, 103, and 104 are separated again after being deflected by the oscillating mirror 106 that is the deflecting means, and guided. An image (latent image) is formed.

  The beams from the light source units 107 and 108 are obliquely incident on the oscillating mirror 106 at different incident angles in the sub-scanning direction so that the light beams from the light source units 107 and 108 are collectively deflected and scanned. ing.

  In the light source units 107 and 108, the light sources for two stations are arranged in the sub-scanning direction, and the angle formed by the light beams from each light source is adjusted to 2.5 °, and the vibration mirror surface 441 described later is used in the sub-scanning direction. Are integrally supported so as to intersect.

  In the present embodiment, the light source unit 107 tilts the light beam (beam) 202 from the lower light source in parallel to the light source unit's emission axis and the light beam (beam) 201 from the upper light source by 2.5 ° with respect to the emission axis of the light source unit. The injection axis is arranged to be inclined 1.25 ° downward with respect to the main scanning plane.

  On the other hand, the light source unit 108 tilts the light beam (beam) 203 from the upper light source parallel to the emission axis and the light beam (beam) 204 from the lower light source to 2.5 ° with respect to the emission axis. Each light source unit 107, 108 is sub-scanned so that it is inclined 1.25 ° upward with respect to the scanning plane, and the emission axis of each light source unit 107, 108 intersects the sub-scanning direction at the vibrating mirror surface 441. The installation height is changed in the direction.

  The light source unit 108 is disposed so as to be positioned lower than the light source unit 107 in the sub-scanning direction, and the incident mirror 111 causes the beams 204, 203, 202, 201 from the respective light sources to be aligned in a vertical direction in the sub-scanning direction. So that the incident angles in the main scanning direction are 22.5 ° (= α / 2 + θd) with respect to the normal line of the oscillating mirror 106, respectively. The light is incident on 106 so as to intersect the sub-scanning direction.

  Each beam is converged in the sub-scanning direction in the vicinity of the vibrating mirror surface by the cylinder lens 113, and after deflection, is incident on the scanning lens 120 while increasing the interval so that the beams are separated from each other. Here, the scanning lens 120 is shared by all stations, and has no convergence in the sub-scanning direction.

  Of the light beams from the light source units 107 and 108 that have passed through the scanning lens 120, the lower beam 204 from the light source unit 108 is reflected by the folding mirror 126 and spotted on the photosensitive drum 101 via the toroidal lens 122. The first image forming station forms a latent image based on yellow image information.

  The upper beam 203 from the light source unit 108 is reflected by the folding mirror 127, forms an image on the photosensitive drum 102 through the toroidal lens 123 and the folding mirror 128, and forms a magenta color as a second image forming station. A latent image based on the image information is formed.

  The lower beam 202 from the light source unit 107 is reflected by the folding mirror 129, forms a spot image on the photosensitive drum 103 via the toroidal lens 124 and the folding mirror 130, and is cyan as a third image forming station. A latent image based on the image information is formed.

The upper beam 201 from the light source unit 107 is reflected by the folding mirror 131, forms a spot image on the photosensitive drum 104 via the toroidal lens 125 and the folding mirror 132, and is black as a fourth image forming station. A latent image based on the image information is formed.
These components are integrally held in a single housing described later.

  Synchronous detection sensors (also referred to as “vibration control PD (photodiode)” or “synchronous detection”) 140 (−image height) and 141 (+ image height) as light beam detection means for controlling the deflection means are: This is an optical sensor including a photodiode (PD) having a light receiving surface for detecting passage of light beams from the light source units 107 and 108. The light beam deflected by the oscillating mirror 106 passes through the scanning lens 120 and is focused and incident on the synchronization detection sensors 140 and 141 by the imaging lenses 143 (−image height) and 144 (+ image height). A detection signal is output, and the deflection means (vibrating mirror 106) is appropriately controlled in the deflection control means based on the detection signal.

  The light receiving surfaces of the synchronization detection sensors 140 and 141 are configured to pass through the imaging lens, enter after passing through the scanning lens 120, or enter after passing through the toroidal lenses 122 to 124. Also good.

  The synchronization detection sensors 140 and 141 for controlling the deflecting means can be arranged so that the synchronization detection signal for each station can be detected, and the number of synchronization detection sensors can be reduced.

  Further, the exit roller portion (left end portion in FIG. 1) of the intermediate transfer belt 105 is provided with overlay accuracy detection means for detecting the overlay accuracy of each color image formed and superimposed at each station. .

  The overlay accuracy detection means reads the detection pattern of the toner image formed on the intermediate transfer belt 105 to detect the main scanning resist and the sub-scanning resist as deviations from the reference station, and periodically performs correction control. Is called.

  In the present embodiment, the overlay accuracy detection means includes an LED element 154 for illumination, a photosensor 155 that receives reflected light, and a pair of condensing lenses 156, and is provided at three positions on the left and right ends and the center of the image. Then, the detection time difference from the reference color black is read in accordance with the movement of the intermediate transfer belt 105.

  As described above, the optical scanning device of the present invention is a light beam detecting means (synchronous detection sensor 140) composed of a PD as a light receiving surface that detects a light beam deflected by the oscillating mirror 106 and scanned on the image plane. 141) and light source driving means for lighting the LD light source unit (light source units 107 and 108) in a pulsed manner in accordance with the timing when the light beam passes through the light receiving surface.

  Next, an operation procedure of the optical scanning device having a light emission amount control period in which the semiconductor laser is forcibly turned off will be described. For simplification of description, the case where only the light source unit 107 of the LD light source unit is turned on will be described.

  When the light beam emitted from the light source unit 107 pulse-driven by the light source driving means 606 is deflected and scanned by the vibrating mirror 106 and the light beam passes over the synchronization detection sensor 141 which is the synchronization detection means, the optical laser The value of the pixel counter in the light source driving unit 606 is reset to zero. In addition, the light source unit 107 can be pulse-driven by appropriately designating the writing start position, end position, dot interval, etc. starting from the synchronization detection sensors 140 and 141 installed on both sides of the scanning region of the light beam. It is possible to form dots at a desired position and width in the formation region.

  Based on the signals detected by the synchronization detection sensors 140 and 141, the amplitude, phase, period, offset, etc. of the oscillating mirror 106 are calculated, and the oscillating mirror 106 is controlled by the deflection control means 610. The LD light source unit is driven and controlled by the light source driving unit 606 in accordance with the operation state of the vibrating mirror 106, and pulse lighting driving that reflects the writing data in the image forming area is performed.

  In FIG. 2, as light beam detection means, synchronization detection sensors 140 (PD−) and 141 (PD +) are installed on both sides outside the image forming area in the light beam scanning area, and the scanning state of the reciprocally scanned light beam is shown. A block configuration diagram is shown in which the vibration mirror 106 is controlled by the deflection control means 610 and the light beam driving means 606 simultaneously modulates and drives the light beam.

  The light beams deflected by the oscillating mirror 106 pass through the end of the scanning lens 120 and are converged and incident by the imaging lenses 143 and 144 to the synchronization detection sensors 140 and 141. Based on this, a synchronization detection signal for each station is generated.

  Conventionally, the relationship between the incident angle α from the light source units 107 and 108 to the vibrating mirror surface and the deflection angle (amplitude) θ0 of the vibrating mirror 106 is α> 2θ0 and the maximum deflection angle 2θmax = α + 2θ0. In order to suppress the rate (θd / θ0) to a predetermined value or less, for example, 0.6 or less in the embodiment, the following equation is set.

θ0 ≧ α / 2> θd
θ0 ≧ θs> θd

  Here, θd is an effective deflection angle for scanning on the photosensitive member, θs is a deflection angle at the time of synchronous detection, and the incident angle of the light beam from the light source units 107 and 108 to the vibrating mirror surface so as to satisfy the above formula. (Incident angle of light beam from light source unit 107, 108 to light beam amplitude center line by vibrating mirror 106) α is set. Specifically, θ0 = 25 °, θd = 15 °, α = 45 °, and θs = 18 °.

  In FIG. 2, the center of amplitude of the light beam by the oscillating mirror 106 is arranged so as to coincide with the optical axis of the scanning lens 120, and the surface shape of the scanning lens 120 or toroidal lens is a curved surface shape that is symmetric along the main scanning direction. I am doing so. Note that the synchronization detection sensors 140 and 141 may be arranged so that θs> α / 2.

  Further, depending on the layout of the apparatus, as shown in FIG. 3, an example in which the amplitude center of the light beam by the vibrating mirror 106 does not coincide with the optical axis of the scanning lens 120, that is, the light beam amplitude center on the light source unit 107, 108 side. There is an example in which the amplitude is shifted, and in that case, it is necessary to control the detection result of the light beam detection means (synchronization detection sensors 140 and 141) by reflecting the amount of deviation from the optical axis of the scanning lens 120. Alternatively, the arrangement of the light beam detection means (synchronization detection sensors 140 and 141) may reflect the amount of deviation from the optical axis of the scanning lens 120.

  By the way, as described above, the vibrating mirror surface is deformed into a wave shape with the reciprocating vibration. The amount of deformation δ becomes maximum when the amplitude is θ0, and there is a tendency that the amount of change increases in proportion to the change from the deflection angle 0 to θ0.

  That is, the deflection angle θd of the vibrating mirror 106 (that is, the light beam) that scans the scanning region is determined by the angle of view of the scanning lens 120. Therefore, the ratio of the deflection angle θd that scans the scanning region to the amplitude θ0, the effective scanning rate. The smaller (θd / θ0) is, the less affected by the mirror deformation.

  However, in order to increase the amplitude θ0, it is necessary to reduce the mass of the substrate (mirror substrate) of the oscillating mirror 106, and conversely, if the mirror substrate is made thinner, the amount of deformation increases.

  In the present invention, the effective scanning rate (θd / θ0) is set so that the angular velocity of the oscillating mirror 106 is within a relatively constant range of the deflection angle, and the deflection angle θd for scanning the scanned region is 60% or less of the amplitude θ0. This suppresses deformation.

  On the other hand, when the incident angle α is increased, it is easily affected by dynamic surface deformation. Specifically, as shown in FIG. 2, the maximum amplitude 2 · θ 0 = 50 °, the incident angle α = 45 °, the scanning angle 2 · θd = 30 °, and the synchronization detection angle 2 · θs = 36 °.

Therefore, in the present invention, as shown in FIG. 2, first, the synchronization detection sensors 140 and 141 which are the light beam detection means are respectively separated by a distance Hs from the intermediate point in the longitudinal direction of the detection means fixing member (shaded portion in the figure) 142. Fix it at both ends. Further, in the housing of the optical scanning device, the detection means fixing member 142 and the scanning imaging optical system (scanning lens 120) are arranged in a predetermined arrangement with respect to the center line of the amplitude of the reciprocating scanning of the light beam by the deflecting means (vibrating mirror 106). A first positioning portion (not shown) for the detection means fixing member 142 and a second positioning portion for the scanning lens 120 are provided to establish the relationship.
Next, positioning means 145 provided at a portion corresponding to an intermediate point between the light receiving surfaces of the synchronization detection sensors 140 and 141 in the detection means fixing member 142 is attached to the first positioning portion of the housing. As a result, the detection means fixing member 142 is positioned so that the intermediate point between the light receiving surfaces of the synchronous detection sensors 140 and 141 serving as the light beam detection means is positioned on the center line of the amplitude of the reciprocal scanning of the light beam by the vibrating mirror 106. Will be positioned.

  Further, the positioning means 146 provided at the central portion of the scanning lens 120 in the main scanning direction is attached to the second positioning portion provided in advance in the housing. As a result, the scanning lens 120, which is one of the optical elements of the scanning imaging optical system, is positioned in the housing so that the optical axis of the scanning lens 120 coincides with the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106. Will be.

  With the above configuration, in FIG. 2, the intermediate point between the light receiving surfaces of the synchronization detection sensors 140 and 141 of the detection means fixing member 142 is positioned on the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106. In addition, the arrangement is such that the optical axis of the scanning lens 120 coincides with the center line. In addition, the light receiving surfaces of the synchronization detection sensors 140 and 141 have the same height Hs from the optical axis of the scanning lens 120 (the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106).

  The positioning means 145 and 146 may be fixed to the positioning portion of the housing by using an adhesive layer or a positioning jig (plate spring, screw, etc.). Thereby, the positioning means 145 and 146 can be integrally fixed to the housing.

  When the synchronization detection sensors are individually fixed to the housing as in the prior art, a positional deviation with respect to the deflection angle θs of each synchronization detection sensor and an error with respect to the interval between the synchronization detection sensors occurred. By fixing the synchronization detection sensors 140 and 141 integrally with the housing via the detection means fixing member 142, it is possible to reduce detection errors when the light beam caused by the positional deviation passes through the light receiving surface. .

  Further, the positioning means 146 of the optical element (scanning lens 120) having the most power in the main scanning direction and the positioning means 145 of the detection means fixing member 142 to which the light receiving surface is fixed are respectively connected to the central axis of the housing (light beam by the vibration mirror 106). By positioning each of the optical elements (scanning lens 120) so as to fit on the center line of the reciprocal scanning amplitude, the positioning means 145 on the central axis can be used even when the optical element (scanning lens 120) expands or contracts due to fluctuations in temperature or humidity. , 146 are fixed, so that the objectivity with respect to the center is maintained, so that the deflection means (vibration mirror 106) can be controlled based on a stable detection signal.

  Accordingly, by monitoring the timing at which the light beam passes on the synchronization detection sensors 140 and 141, it is possible to grasp the vibration state (phase, period, center shift amount, magnification error, etc.) of the vibration mirror 106. .

  In addition, the start position of the light emission amount control period in which the pixel clock count measuring unit 611 that counts the pixel clock from the passage of the light beam in either of the synchronization detection sensors 140 and 141 is forcibly turned off in the same manner as the synchronization detection of the write start position. Then, drive control of the light sources (light source units 107 and 108) is performed via the light source drive means 606 so as to appropriately control the end position and the section width.

  Further, the vibration state of the vibration mirror 106 is sent to the deflection control means 610, and the vibration mirror 106 is controlled to perform a desired vibration according to control parameters such as a drive voltage and a vibration frequency.

  In FIG. 2, the positioning means 145 and 146 are provided at the center of the detection means fixing member 142 (intermediate point of the synchronization detection sensors 140 and 141) and the center of the scanning lens 120 in the main scanning direction (optical axis), respectively. However, the present invention is not limited to this. For example, depending on the layout of the apparatus, as shown in FIG. 4, the positioning means 145 and 146 are respectively positioned at the midpoint of the synchronization detection sensors 140 and 141 of the detection means fixing member 142 and the central portion in the main scanning direction of the scanning lens 120 (light You may provide in the location which shifted | deviated from the axis | shaft. At this time, the positioning part of the housing is also shifted correspondingly. Similarly to FIG. 2, the synchronization detection sensor 140 of the detection means fixing member 142 is placed on the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106. 141, the intermediate point between the light receiving surfaces is located, and the optical axis of the scanning lens 120 coincides with the center line. In addition, the light receiving surfaces of the synchronization detection sensors 140 and 141 have the same height Hs from the optical axis of the scanning lens 120 (the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106).

FIG. 5 shows the positional deviation of the light receiving unit due to the individual difference between the synchronization detection sensors 140 and 141.
The light receiving portions in the synchronization detection sensors 140 and 141 are light receiving portions (thick solid lines in the center of the figure) due to individual differences due to deviations in the manufacturing position of the elements of the light receiving portions (also referred to as light receiving surfaces) or mounting positions on the substrate. There is a case where it is shifted by Δd in the main scanning direction as indicated by 140a and the light receiving portion (broken line in the figure) 140a ′.

  Even if the synchronization detection sensors 140 and 141 can be attached to the predetermined positions of the optical scanning device without any positional deviation, the light receiving portions in the synchronization detection sensors 140 and 141 are shifted in the Δd main scanning direction. .

  Further, since this positional deviation Δd is not a constant value for each individual, it is very difficult to adjust the amplitude data of the deflecting means (vibrating mirror 106) in order to cope with the positional deviation. Also, the output image varies from individual to individual.

  Therefore, as shown in FIG. 6, the left and right synchronization detection sensors 140 and 141 are fixed via the detection means fixing member 142 so that the respective light receiving portions 140 a and 141 a are at a desired interval, and the light receiving portions 140 a and 141 a Positioning means 145 is provided at an intermediate center point and fixed to the positioning portion of the housing. Accordingly, the light receiving portions 140a and 141a of the synchronization detection sensors 140 and 141 can stabilize the arrangement relationship with the scanning lens 120 fixed to the positioning portion of the housing by the positioning means 146.

  In the left and right synchronization detection sensors 140 and 141 which are light beam detection means, the distance between the left and right synchronization detection sensors 140 and 141 is set to a distance Hs from the target axis of the detection means fixing member 142 in consideration of individual differences of the light receiving units. Then, the positioning means 145 is positioned and fixed to the positioning portion of the housing. At this time, the positioning means 145 is fixed by an adhesive layer or a fixing member (plate spring, screw, etc.). As a result, it is possible to correct the positional deviation error of the detection unit due to individual differences to the detection means fixing member 142 and to fix the light receiving unit at a desired interval.

FIG. 7 is a schematic diagram of detection signals of the synchronization detection sensors 140 and 141 when the synchronization detection sensor 141 (PD +) is displaced in the outer direction of the light beam scanning region.
In FIG. 7A, assuming that the light receiving unit 141a of the synchronization detection sensor 141 is fixed as the light receiving unit 141a 'when the light receiving unit 141a of the synchronization detection sensor 141 is moved outward from the center of amplitude of the light beam by the amount of deviation dw. The time from when the light beam passes through the portion 141a ′ to the maximum amplitude and again passes through the light receiving portion 41a ′ is a detection signal as indicated by a broken line in FIG. The detection time t1 ′ indicated by the dotted line due to the positional deviation of is shorter than the detection time t1 in the case of the light receiving unit 141a.

  At this time, since the passage time (detection time) on the synchronization detection sensor 140 (PD−) side remains t1, in the control program for the deflecting means (vibrating mirror 106), the scanning state of the light beam is the synchronization detection sensor 141. It is erroneously determined that the side deflection angle has decreased or the amplitude center has shifted.

For example, when the scanning frequency fd of the oscillating mirror 106 is 2500 Hz, the maximum deflection angle 2θ0 = 30 °, the image height ± 120 mm, and the arrangement angle ± 2θs = 25 ° with respect to the amplitude center of the light beam of the synchronization detection sensors 140 and 141 When the image height is ± 100 mm and the time from the image height 0 to the deflection angle θ is T, the following relational expression is obtained.
T = (1 / 2πfd) * sin ⁻¹ (θ / θ0)

At this time, if the time T100 passing through the image height of 100 mm and the time up to the image height of 101 mm are T101, T100 = 65.2554 μs and T101 = 66.1782 μs. If it is twice T100, the time of scanning the light beam with the positional deviation dw = 1 mm of the light receiving surface is 0.9228 [μs], and the rate of error due to the width of the light receiving surface is 0.9228 / (2 * T100) × 100 = 0.707 [%].
This greatly exceeds the allowable limit of jaggy (jagged lines) of about 0.01%, and the influence on the image quality is great.

  At present, the synchronization detection sensors 140 and 141 can be arranged on the same surface at intervals of about several μm, and the positional deviation of the light beam detection means (synchronization detection sensors 140 and 141) is set to dw = 10 μm. If it is arranged, the time required for the light beam to pass is 0.0916 μs, and the error rate due to the boundary width is within 0.0087%, which is far below the allowable limit of jaggies, and is measured by the synchronization detection sensors 140 and 141. Based on the data, it is possible to appropriately perform correction of the beam spot position by the light beam, correction of the writing start position, and attitude control of the vibrating mirror.

  In FIG. 7B, the thick line portion (± 2θd) of the sine wave curve of the vibrating mirror 106 corresponds to the image forming area, and the synchronization detection sensors 140 and 141 are installed outside the image forming area (± 2θs). The beam scanning state is detected. Since the light source means (light source units 107 and 108) are provided on the synchronization detection sensor 141 (PD +) side, the return light is generated when the light beam is scanned on the synchronization detection sensor 141 (PD +) side. . In the vicinity of the incident angle α of the light beam from the light source means (light source units 107 and 108) to the vibrating mirror surface, the deflection angle of the vibrating mirror 106 is θs to θ0 (scanning angles 2θs to 2θ0). By providing the light emission amount control period, it is possible to prevent the light emission oscillation of the semiconductor laser constituting the light source means (the light source units 107 and 108) due to the return light from becoming unstable.

8 and 9 are schematic views when the vibration state of the vibration mirror 106 is changed.
FIG. 8 shows a case where the amplitude of the oscillating mirror is larger (dotted line) than the standard state (solid line). Until the scanned light beams pass through the respective synchronization detection sensors 140 and 141 installed on both sides outside the image forming area in the main scanning direction, reach the maximum image height, and pass through the synchronization detection sensors 140 and 141 again. This time changes with the same tendency on both the A side (+ side) and the B side (− side). The relationship is proportional to the amplitude tendency of the vibrating mirror 106. Therefore, a relational expression between the change in the amplitude of the vibrating mirror 106 and the installation position of the synchronization detection sensors 140 and 141 is stored in a database in advance, so that the light emission amount control for appropriately forcibly turning off according to the amplitude state of the vibrating mirror 106 is performed. A period can be set.

  Specifically, when the light source means (light source units 107 and 108) are arranged in the A side direction, the time interval for the light beam to pass through the synchronous detection sensors 140 and 141 is indicated by the dotted line in FIG. Since the time required for the light beam to reach the incident angle α is increased, the forced extinguishing time needs to be advanced (FIG. 8B). Conversely, since the time for the light beam to return from the maximum amplitude and reach the incident angle α again is delayed, it is necessary to delay the end of the light emission amount control period during which the light is forcibly turned off (FIG. 8B).

  FIG. 9 shows a case where the amplitude center at the image plane position of the vibrating mirror 106 is shifted to the + image height side. In the synchronization detecting sensor 141 on the + image height side, the scanning beam passes and the time from reaching the maximum image height to returning again increases. On the other hand, the synchronization detecting sensor 140 on the opposite side decreases it. (FIG. 9A).

  Thus, when the amplitude center of the vibration mirror 106 is shifted to one side, the time during which the light beam is scanned and passed through the synchronization detection sensors 140 and 141 in the installation relationship between the amplitude center of the vibration mirror 106 and the synchronization detection sensors 140 and 141. By making the relational expression in a database, it is possible to set a desired light emission amount control period during which the light is forcibly turned off.

10 to 12, the time t <b> 1 until the light beam scanned through the synchronization detection sensor 141 passes, reaches the maximum amplitude, and returns again, and the light beam scanned through the synchronization detection sensor 141 are in the same direction. The relationship with time t2 until passing is shown.
FIG. 10 shows a case where the amplitude of the oscillating mirror 106 is larger than that in the standard state (solid line) (dotted line). Since the deflection angle of the oscillating mirror 106 is larger in the case of the dotted line than in the case of the solid line, the time t1 ′ in the dotted line is larger than the time t1 in the solid line, but the oscillation cycle of the oscillating mirror 106 is changed. Therefore, time t2 (solid line) and time t2 ′ (dotted line) do not change. Therefore, by measuring the time t1 and the time t2 based on the detection signals of the synchronization detection sensors 140 and 141, the deflection angle of the vibrating mirror 106, that is, the fluctuation of the maximum amplitude of the light beam by the vibrating mirror 106 can be measured. Based on the result, the control means may control the deflection means (vibrating mirror 106) so that the maximum amplitude of the light beam becomes constant. At the same time, the light source units 107 and 108 may be driven and modulated by the light source driving means 606 so as to change the setting of the light emission amount control period corresponding to the forced light extinction.

  FIG. 11 shows a case where the center of amplitude of the vibrating mirror 106 is shifted to the image height + side. As in FIG. 10, since the oscillation cycle of the oscillating mirror 106 does not change, the time t2 (solid line) and the time t2 ′ (dotted line) do not vary, but the dotted line shifts to the image height + side than the solid line. The time t1 ′ (dotted line) is larger than the time t1 (solid line) by the amount. At this time, if the synchronization detection sensor is installed only at the end on one side in the main scanning direction, the amplitude in the case of the solid line is larger than that in the case of the dotted line at the end on the opposite side. Cannot be measured, and it cannot be distinguished whether the amplitude center of the vibrating mirror has shifted or the amplitude has increased. In order to observe the amplitude fluctuation of the vibration mirror 106 and the state of the vibration center, it is necessary to install the synchronization detection sensors 140 and 141 on both outer sides of the image forming area in the main scanning direction as in the present invention.

  In the present invention, the deflection control means controls the deflection means (vibrating mirror 106) so as to correct the shift amount of the amplitude center of the light beam obtained based on the detection signals detected by the synchronization detection sensors 140 and 141. You should do that. At the same time, the light source units 107 and 108 may be driven and modulated by the light source driving means 606 so as to change the setting of the light emission amount control period corresponding to the forced light extinction.

FIG. 12 shows a case where the oscillation cycle of the oscillating mirror 106 varies. In this case, the time t1 ′ and the time t2 ′ in the case of the dotted line are longer than the time t1 and the time t2 in the case of the solid line by the increase of the oscillation cycle of the oscillating mirror 106. Thereby, it is possible to detect fluctuations in the scanning frequency of the light beam. In the present invention, the deflection control unit controls the deflection unit (vibrating mirror 106) so as to correct the fluctuation of the scanning frequency of the light beam obtained based on the detection signals detected by the synchronization detection sensors 140 and 141. It is good to do. At the same time, the light source units 107 and 108 may be pulse-modulated and driven by the light source driving means 606 so as to increase the period and the length of the light emission amount control period forcibly turning off correspondingly.
Note that only one of the controls by the deflection control means based on the results of FIGS. 10 to 12 may be executed, or two or more controls selected from these may be executed.

FIG. 13 is a schematic diagram of a vibration mirror control system for suppressing fluctuations and disturbances of the vibration state that occur in the vibration mirror 106 over time due to environmental changes such as temperature changes.
The deflection control means (controller) 610 is based on the detection signal detected by the synchronization detection sensors 140 and 141, the amplitude amount which is the deflection angle of the vibrating mirror 106, the shift amount of the amplitude center at the image plane position, and the phase based on the detection signal interval. Feedback control is performed in which the control voltage (applied voltage) is adjusted through the oscillating mirror drive unit (driver) 603 and applied to the oscillating mirror 106 so as to obtain the target deflection angle and deviation. A stable vibration state of 106 can be realized.

  For example, when the amplitude of the vibrating mirror 106 increases, as shown in FIG. 14, the deflection control means (controller) 610 detects the relationship between the detection signals of the synchronization detection sensors 140 and 141 and the reference phase clock. The timing deviation is grasped as a deviation, and the oscillating mirror 106 is controlled by decreasing the applied voltage through the oscillating mirror driver (driver) 603 in order to reduce the amplitude (the dotted curve in FIG. 14) increased from the deviation. become.

Based on FIG. 15, the vibration mirror used for the optical scanning device in this embodiment is demonstrated.
FIG. 15 is an exploded perspective view of the vibrating mirror module. In the present embodiment, an example of an electromagnetic drive method will be described as a method for generating the rotational torque of the vibrating mirror.

  As shown in the figure, a vibrating mirror 441 that forms the mirror surface of the vibrating mirror is pivotally supported by a torsion beam 442 and, as will be described later, is manufactured by penetrating the outer shape by etching from a single Si substrate. A vibrating mirror substrate 440 is configured as a unit that is attached to 448 and integrally includes the vibrating mirror (FIG. 15A).

  In the present embodiment, a module is shown in which a pair of vibrating mirror substrates 440 are integrally supported back to back. This back-to-back configuration uses one corresponding to the “opposite scanning method”, and in this embodiment, the “one-side scanning method” is exemplified as described above. It is unnecessary. Of course, a configuration dedicated to the “single-side scanning method” that supports only the single vibrating mirror substrate 440 may be used.

  The support member 445 is formed of a resin and is positioned at a predetermined position of the circuit board 449. The vibration mirror substrate 440 is arranged such that the torsion beam 442 is orthogonal to the main scanning plane and the mirror surface is at a predetermined angle with respect to the main scanning direction. Here, an edge in which metal terminal groups are arranged so that a positioning portion 451 for positioning so as to be inclined by 22.5 ° and a wiring terminal 455 formed on one side of the mounting substrate 448 of the vibration mirror substrate 440 are in contact with each other at the time of mounting. The connector portion 452 is integrally formed (FIG. 15D).

  The vibrating mirror substrate 440 has one side inserted into the edge connector 452 and is fitted inside the presser claw 453. The both sides of the back of the substrate are supported along the positioning portion 451, and electrical wiring is provided. At the same time, each vibrating mirror substrate 440 can be individually replaced.

  The circuit board 449 is mounted with a control IC, a crystal oscillator, and the like that constitute a drive circuit for the vibrating mirror, and a power supply and a control signal are input / output via the connector 454.

  The oscillating mirror 460 includes a movable part that forms a mirror surface on the surface and forms a vibrator, a torsion beam that supports the movable part, and a frame that forms a support part, and is formed by cutting an Si substrate by etching.

  In this embodiment, two substrates of 60 μm and 140 μm called SOI substrates are manufactured using a wafer bonded in advance with an oxide film interposed therebetween.

  First, a torsion beam 442, a vibration plate 443 on which a planar coil is formed, a reinforcing beam 444 that forms a skeleton of a movable part, a frame 446, and the like by a dry process by plasma etching from the surface side of a 140 μm substrate (second substrate) 461 The remaining part of the film is penetrated to the oxide film, and then the movable mirror 441 and the frame 447 are left by anisotropic etching such as KOH from the surface side of the 60 μm substrate (first substrate) 462. The other part is penetrated to the oxide film, and finally, the oxide film around the movable part is removed and separated to form the structure of the vibrating mirror (FIGS. 15A to 15C).

  Here, the torsion beam 442 and the reinforcing beam 444 had a width of 40 to 60 μm. As described above, it is desirable that the moment of inertia I of the vibrator is small in order to increase the deflection angle. On the other hand, the mirror surface is deformed by the inertial force. .

  Further, an aluminum thin film is vapor-deposited on the surface side of the 60 μm substrate 462 to form a reflection surface. On the surface side of the 140 μm substrate 461, a terminal 464 wired with a coil pattern 463 and a torsion beam with a copper thin film, and for trimming Patch 465 is formed.

  Naturally, a configuration may be adopted in which a thin film permanent magnet is provided on the diaphragm 443 side and a planar coil is formed on the frame 447 side.

  On the mounting substrate 448, a frame-shaped base (not shown) on which the vibration mirror 460 is mounted and a yoke 470 formed so as to surround the vibration mirror are provided. A pair of permanent magnets 450 that generate a magnetic field in a direction orthogonal to the rotation axis are joined together.

  The vibrating mirror 460 is mounted on the pedestal with the mirror surface facing up, and a Lorentz force is generated on each side parallel to the rotation axis of the coil pattern 463 by passing an electric current between the terminals 464, and the torsion beam 442 is twisted. Then, a rotational torque T for rotating the oscillating mirror 441 is generated.

  Therefore, the movable mirror 441 can be reciprocally oscillated by alternately switching the direction of the current flowing through the coil pattern 463.

  When the current switching period is brought close to the natural frequency of the primary vibration mode with the torsion beam as the rotation axis of the structure constituting the vibrating mirror, the so-called resonance frequency f0, the amplitude is excited and a large deflection angle is obtained. Obtainable.

  Therefore, normally, the scanning frequency fd is controlled so as to be set or followed in accordance with the resonance frequency f0. However, as described above, the resonance frequency f0 is the moment of inertia of the vibrator constituting the vibration mirror. Therefore, if there is a variation in the dimensional accuracy of the finished product, a difference occurs between individuals, making it difficult to align the scanning frequencies fd of the vibrating mirrors.

  The variation of the resonance frequency f0 is about ± 200 Hz depending on the process capability. For example, when the scanning frequency fd = 2 kHz, a scanning line pitch shift corresponding to 1/10 line occurs. When the A4 size is output, a magnification shift of several tens of mm occurs at the paper edge.

  For this reason, those having similar resonance frequencies f0 are ranked by sorting, and the scanning frequency fd is selected and set according to each rank. However, if the resonance frequency f0 varies greatly, the number of ranks increases. Therefore, the number of options for the driving circuit of the vibrating mirror and the scanning frequency fd must be increased, so that the production efficiency is low, and it is necessary to replace the vibrating mirror with the same rank when performing replacement.

  Therefore, in this embodiment, before mounting on the mounting substrate, the moment of inertia I is adjusted by cutting the patch 465 formed on the back side of the movable part with a carbon dioxide laser or the like to gradually reduce the mass of the movable part. However, even if there is a dimensional difference between individuals, the resonance frequency f0 is adjusted so as to fall within ± 50 Hz so that the resonance frequencies f0 substantially coincide with each other.

  A fixed scanning frequency fd is set within the ranked frequency bands regardless of the resonance frequency f0.

  In addition, as described above, the vibration state of the MEMS oscillating mirror is set to (center of amplitude, deflection width, deflection angle) due to individual differences such as variations in the shape of the mirror and beam and mounting errors between the coil and the core. There is some variation. Therefore, when installing the oscillating mirror in the housing, once the oscillating mirror is set, the light beam is deflected and scanned, and the detection signal is observed while monitoring the detection signal that the scanned light beam passes through the light beam detecting means. Adjust the tilt angle around the center of rotation of the oscillating mirror so that the waveform becomes the desired timing, correct the deviation for each individual, such as the center of amplitude, and adjust the oscillating mirror to an appropriate position. It is good to fix.

FIG. 16 is a block diagram of a drive circuit that amplifies the vibration mirror.
As described above, an AC voltage or a pulse wave voltage is applied to the planar coil formed on the back side of the oscillating mirror 106 so that the direction in which the current flows alternately from the oscillating mirror driving unit 603 is switched. At this time, the gain adjusting unit 602 performs reciprocal vibration by adjusting the gain of the current flowing through the planar coil so that the deflection angle θ is constant.

  FIG. 17 is a diagram illustrating the relationship between the frequency f for switching the direction of current flow and the deflection angle θ with respect to driving of the vibrating mirror 106. Generally, the frequency characteristic has a peak at the resonance frequency f0, and if the scanning frequency fd is made to coincide with the resonance frequency f0, the deflection angle can be maximized, but the deflection angle changes steeply near the resonance frequency.

  Accordingly, the drive frequency applied to the fixed electrode of the oscillating mirror 106 in the drive control unit (the drive pulse generating unit 601, the gain adjusting unit 602, and the oscillating mirror driving unit 603), which is initially the deflection control unit 610 of the oscillating mirror 106. Can be set to match the resonance frequency, but when the resonance frequency fluctuates due to changes in the spring constant due to temperature changes, the deflection angle drastically decreases, and the stability over time is poor. is there.

  Therefore, in this embodiment, the scanning frequency fd is fixed to a single frequency that is excluded from the resonance frequency f0, and the deflection angle θ can be increased or decreased according to gain adjustment.

  Specifically, with respect to the resonance frequency f0 = 2 kHz, the scanning frequency fd is set to 2.5 kHz, and the deflection angle θ is adjusted to ± 25 ° by gain adjustment.

  Over time, the deflection angle θ is obtained by detecting a light beam scanned by the vibrating mirror 106 between a detection signal detected at the time of backward scanning and a detection signal detected at the time of forward scanning by the synchronization detection sensor 141 provided at the start end of the scanning region. Detection is performed based on the time difference, and the deflection angle θ is controlled to be constant.

  As a result, even when temperature fluctuations occur during measurement, the deflection angle θ can be kept constant, and the linear velocity of the light beam on the image plane can be kept substantially constant.

Also, as shown in FIG. 18, since the vibrating mirror 106 is resonantly vibrated, the scanning angle θ changes in a sin wave shape with time t.
Therefore, when the maximum deflection angle of the vibrating mirror, that is, the amplitude is θ0, it is expressed by the following equation.
θ = θ0 · sin2πfd · t

Further, when the synchronization detection sensor 141 detects a light beam corresponding to the scanning angle 2θs, detection signals are generated in the forward scanning and the backward scanning, and using the time difference T, it is expressed by the following equation, and θs is fixed. Therefore, it can be seen that the maximum deflection angle θ0 can be detected by measuring T.
θs = θ0 · cos2πfd · T / 2

  Note that, during the period from the beam detection in the backward scanning to the beam detection in the forward scanning, in terms of the swing angle of the oscillating mirror 106, the light emission of the light source is prohibited during the period of θ0> θ> θs.

  By the way, on the photosensitive drum surface, which is the surface to be scanned, it is necessary to form main scanning dots so that the intervals between the pixels are uniform over time.

  On the other hand, as shown in FIG. 19, in the vibrating mirror 106, since the rate of change of the deflection angle θ decreases with time t, the pixel interval is extended on the scanned surface as it goes to both ends of the main scanning region. .

  In general, this deviation is corrected by using an f · arcsin lens as the scanning lens 120. However, when the pixel clock is modulated at a single frequency, as in the case of scanning with a polygon mirror, the scanning angle 2θ with respect to time. In order to change at a constant speed, that is, it is necessary to set the power (refractive power) along the main scanning direction so that the correction amount of the main scanning position is maximized at the end of the main scanning region. .

At this time, assuming that the image height is 0, that is, the time from the image center to an arbitrary image height H is t, the relationship between the image height H and the shake angle θ (scanning angle 2θ) is as follows. Note that ω is a constant.
H = ω · t = (ω / 2πfd) · sin−1 (θ / θ0)

  In addition, according to the operating state of the oscillating mirror 106 due to disturbance, by designating an appropriate writing start position by two-point synchronization and controlling the pixel position and interval, a high-quality image with less positional deviation can be formed. Can do.

  However, as the amount of correction of the so-called linearity of the pixel spacing increases, the power deviation along the main scanning direction of the scanning lens increases, and the change in the beam spot diameter corresponding to each pixel on the scanned surface also increases. End up. Further, as described above, since the center of amplitude of the oscillating mirror 106 and the optical axis do not coincide with each other, a scanning lens having an asymmetric curved surface on the optical axis is required. Therefore, in this embodiment, the phase Δt of the pixel clock is mainly set. By varying according to the scanning position, the deviation of the power of the scanning lens 120 along the main scanning direction is made as small as possible and the asymmetric component is corrected.

Now, assuming that the change in the scanning angle accompanying the change in the phase Δt of the pixel clock is 2Δθ, the following relational expression is obtained.
H = (ω / 2πfd) · sin−1 {(θ−Δθ) / θ0}
Δθ / θ0 = sin2πfdt−sin2πfd (t−Δt)

Here, when the scanning lens 120 has a power distribution close to that of the fθ lens and the residual is corrected by the phase Δt of the pixel clock, the following relational expression is obtained.
H = (ω / 2πfd) · {(θ−Δθ) / θ0}
= (Ω / 2πfd) · sin−1 (θ / θ0)
Δθ / θ0 = θ / θ0-sin-1 (θ / θ0)

At this time, the phase Δt (sec) of the predetermined pixel along the main scanning direction may be pulse-modulated in the light source (light source units 107 and 108) so as to be determined based on the following relational expression.
(Θ / θ0) −sin−1 (θ / θ0) = sin2πfdt−sin2πfd (t−Δt)

FIG. 20 is a block diagram of a drive circuit that modulates a semiconductor laser that is a light source in the light source units 107 and 108.
Image data is temporarily stored in the frame memory, read out sequentially to the image processing unit, and pixel data for each line is formed according to the matrix pattern corresponding to the halftone while referring to the relationship before and after, corresponding to each light source Transferred to the line buffer.

  Further, the write control unit reads each from the line buffer using the synchronization detection signal as a trigger, and modulates it independently.

  Next, a clock generation unit that modulates each light emitting point in the upper half block of FIG. 20 will be described. The counter counts the high-frequency clock VCLK generated by the high-frequency clock generator, and the comparison circuit gives this count value, a preset value L set in advance based on the duty ratio, and the transition timing of the pixel clock from the outside. The phase data signal H that indicates the phase shift amount is compared, and when the count value matches the set value L, the control signal L that instructs the falling edge of the pixel clock PCLK matches the phase data H. A control signal h for instructing the rising edge of the pixel clock PCLK is output to the pixel cook control circuit. At this time, the counter is reset simultaneously with the control signal h, and counting from 0 is performed again, whereby a continuous pulse train can be formed.

  In this way, the phase data signal H is given for each clock, and the pixel clock PCLK whose pulse cycle is sequentially changed is generated. In this embodiment, the pixel clock PCLK is divided by 8 of the high frequency clock VCLK so that the phase can be varied with a resolution of 1/8 clock.

FIG. 21 is an example in which the phase of an arbitrary pixel is shifted in the drive circuit of FIG. 20, and is an example in which the phase is delayed by 1/8 clock.
When the duty is 50%, a set value L = 3 is given, and the counter counts 4 and the pixel clock PCLK falls. Assuming that the 1/8 clock phase is delayed, phase data H = 6 is given and rises with 7 counts. At the same time, the counter is reset, so it falls again at 4 counts. That is, the adjacent pulse period is shortened by 1/8 clock.

  The pixel clock PCLK generated in this way is supplied to the light source driving unit 606, and the semiconductor laser is driven by the modulation data in which the pixel data read from the line buffer is superimposed on the pixel clock PCLK.

  FIG. 22 shows the correction amount of the main scanning position in each pixel according to the main scanning position when modulated at a single frequency. Multiple main scan areas, in FIG. 22, the main scan area is divided into 8 areas, and approximated by a polygonal line, the number of phase shifts is set for each area so that the main scan position shift is zero at the boundary of each area And correct it stepwise.

For example, assuming that the number of pixels in the i region is Ni, the shift amount in each pixel is 1/16 unit of the pixel pitch p, and the deviation of the main scanning position at both ends of each region is ΔLi, the following relational expression is obtained: What is necessary is just to shift a phase for every ni pixel.
ni = Ni · p / 16ΔLi

Assuming that the pixel clock is fc, the total phase difference Δt is expressed by the following relational expression using the number of phase shifts Ni / ni. Similarly, the phase difference Δt in the N-th pixel is also the phase shift up to that time. Can be set by the cumulative number.
Δt = 1 / 16fc × ∫ (Ni / ni) di

  Note that the divided region width may be equal or unequal, and the number of divisions may be any number. However, when the shift amount in each pixel is increased, the step is easily noticeable on the image. Therefore, it is desirable that the pixel pitch p is equal to or less than ¼ unit. Conversely, if the phase shift amount is small, the number of phase shifts increases and the memory capacity increases. Also, the smaller the number of divisions, the smaller the memory capacity. Therefore, it is efficient to set the area width of the area where the main scanning position deviation is large and to increase the area width of the small area.

  FIG. 23 shows a case where the reflecting surface of the vibrating mirror 106 is deformed by δ around the rotation axis. For example, when the reflecting surface 441 of the oscillating mirror 106 is convexly deformed as shown in FIG. 22C, the deflected light beam collimated in parallel is diffused by the oscillating mirror 106, and is reflected on the image plane. It causes image deterioration such as beam diameter thickening. In addition, since the return light reflected by the oscillating mirror also returns to the light source again in a range wider than the incident angle α, the APC is set when the light emission amount control period forcibly turning off is set wider or when the light cannot be turned off. By not performing the control, it is possible to perform stable oscillation light emission of the semiconductor laser.

  Therefore, when deformation on the reflecting surface of the vibrating mirror 106 is predicted in advance, a substantially constant beam diameter is obtained by applying pulse modulation driving for correcting beam thickness to the light source unit (light source units 107 and 108). be able to.

  Further, in order to perform correction in real time, an operation for calculating an appropriate pulse drive correction method from the fluctuation of the light beam passage time interval at the synchronization detection sensors 140 and 141 and the information of the beam profile obtained on the detection surface. It is necessary to provide a part. Similarly, it is necessary to provide a calculation unit for calculating an appropriate pulse drive correction method for the start, end position, and period of the light emission amount control period that is simultaneously forcedly turned off.

  FIG. 24 shows a housing configuration example of an optical scanning device in which a plurality of synchronization detection sensors 140 and 141 are fixed to a housing via a detection means fixing member 142. In FIG. 24, reference numeral 250 denotes a housing body, and 255 denotes a beam passage frame.

  Here, in the housing body 250, the detection means fixing member 142 and the scanning imaging optical system (scanning lens 120) are placed in a predetermined arrangement relationship with respect to the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106. A first positioning portion (not shown) for the detection means fixing member 142 and a second positioning portion (not shown) for the scanning lens 120 are provided.

  Regarding the installation of the oscillating mirror 106, the scanning lens 120, and the synchronization detection sensors 140 and 141 on the housing body 250, first, the synchronization detection sensors 140 and 141 are placed in the middle in the longitudinal direction of the detection means fixing member 142 It is fixed to both ends separated from the point by a distance Hs.

  Next, the oscillating mirror 106 is arranged on the housing main body 250 so that the amplitude center line of the light beam by the oscillating mirror 106 passes through the target position. At this time, the oscillating mirror 106 which is a oscillating mirror module is mounted on an optical housing integrally formed with a side wall 257 erected so as to surround the oscillating mirror module, and the upper edge of the side wall 257 is sealed by the upper cover 258. Then, by blocking from the outside air, the change in amplitude due to the convection of the outside air is prevented. A flat transmission window 259 is provided in the opening of the side wall through which the light beam enters and exits.

  Next, positioning means 146 provided at the center of the scanning lens 120 in the main scanning direction is attached to the second positioning portion of the housing body. As a result, the scanning lens 120 is positioned on the housing main body 250 so that the optical axis of the scanning lens 120 coincides with the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106.

  Next, positioning means 145 provided at a portion corresponding to an intermediate point between the light receiving surfaces of the synchronization detection sensors 140 and 141 in the detection means fixing member 142 is attached to the first positioning portion of the housing body 250. As a result, the detection means fixing member 142 is positioned so that the intermediate point between the light receiving surfaces of the synchronous detection sensors 140 and 141 serving as the light beam detection means is positioned on the center line of the amplitude of the reciprocal scanning of the light beam by the vibrating mirror 106. Will be positioned.

  With the above configuration, the midpoint between the light receiving surfaces of the synchronous detection sensors 140 and 141 of the detection means fixing member 142 is positioned on the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106, and the center line In this arrangement, the optical axes of the scanning lenses 120 coincide with each other. In addition, the light receiving surfaces of the synchronization detection sensors 140 and 141 have the same height Hs from the optical axis of the scanning lens 120 (the center line of the amplitude of the reciprocating scanning of the light beam by the vibrating mirror 106).

  As an example of the configuration of the optical scanning device according to the present invention, an example is shown in which the center point between the light receiving surfaces of the light beam detecting means is positioned on the amplitude center line of the light beam by the deflecting means. It is not always necessary to match the center position of the light receiving surface, and the light receiving surface can be fixed integrally at a desired position via the detection means fixing member. In that case, the timing at which the light beam passes between the light receiving surfaces of one light beam detecting means (+ image height) and the other light beam detecting means (-image height) is shifted. It is necessary to reflect in the reference data.

FIG. 25 shows an example of an image forming apparatus equipped with the optical scanning device 900 shown in FIG.
Around the black photosensitive drum 901 (photosensitive drum 104 in FIG. 1), a charging charger 902 for charging the photosensitive drum 901 to a high voltage, and a toner charged to an electrostatic latent image recorded by the optical scanning device 900 And a developing device 904 for making the toner image visible, and a cleaning device 905 for scraping and storing the toner remaining on the photosensitive drum. The peripheral configuration of the other photosensitive drums (photosensitive drums 101, 102, and 103 in FIG. 1) is the same. Image recording is performed on the photosensitive drum every two lines in one cycle by reciprocating scanning of the vibrating mirror.

The above-described image forming stations are arranged in parallel in the moving direction of the intermediate transfer belt 906, and yellow, magenta, cyan, and black toner images are sequentially transferred onto the intermediate transfer belt 906 at appropriate timing, and are superimposed to form a color image. The
Each image forming station has basically the same configuration except that the toner color is different.

  On the other hand, recording paper as a recording medium is supplied from a paper supply tray 907 by a paper supply roller 908, and is sent out by a registration roller pair 909 in accordance with the recording start timing in the sub-scanning direction, and a toner image is transferred from the intermediate transfer belt 105. Is done. Thereafter, fixing is performed by the fixing device 910, and the sheet is discharged onto the discharge tray 911 by the discharge roller pair 912.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and other embodiments, additions, modifications, deletions, etc. Can be changed within the range that can be conceived, and any embodiment is included in the scope of the present invention as long as the effects and advantages of the present invention are exhibited.

1 is a perspective view illustrating a configuration example of an image forming apparatus according to the present invention. It is the schematic which shows the structural example (1) of the optical scanning device concerning this invention. It is the schematic which shows the structural example (2) of the optical scanning device concerning this invention. It is the schematic which shows the structural example (3) of the optical scanning device based on this invention. It is a figure which shows the example of position shift of the light-receiving part by the individual difference of a synchronous detection sensor. It is the schematic which shows the arrangement | positioning relationship of a synchronous detection sensor, a detection means fixing member, and a scanning lens. It is a schematic diagram of the detection signal of a synchronous detection sensor when a synchronous detection sensor raise | generates position shift to the outer side direction of a light beam scanning area | region. It is a schematic diagram of the detection signal (1) of a synchronous detection sensor when the vibration state of a vibration mirror changes. It is a schematic diagram of the detection signal (2) of a synchronous detection sensor when the vibration state of a vibration mirror changes. Relationship between time t1 until the light beam scanned through the synchronization detection sensor passes through and reaches the maximum amplitude and returns again, and time t2 until the light beam scanned through the synchronization detection sensor passes in the same direction It is a figure which shows (1). Relationship between time t1 until the light beam scanned through the synchronization detection sensor passes through and reaches the maximum amplitude and returns again, and time t2 until the light beam scanned through the synchronization detection sensor passes in the same direction It is a figure which shows (2). Relationship between time t1 until the light beam scanned through the synchronization detection sensor passes through and reaches the maximum amplitude and returns again, and time t2 until the light beam scanned through the synchronization detection sensor passes in the same direction It is a figure which shows (3). It is a schematic diagram which shows the structure of the control system of a vibration mirror. It is a figure which shows the relationship between the detection signal of a synchronous detection sensor when the amplitude fluctuation | variation of a vibration mirror generate | occur | produces, and a reference | standard phase clock. It is a figure which shows the structural example of a vibration mirror. It is a block diagram of the drive circuit which makes a vibration mirror amplitude. It is a figure which shows the relationship between the frequency f which switches the direction through which an electric current flows regarding the drive of a vibration mirror, and deflection angle (theta). It is a figure which shows the relationship between the deflection angle (theta) in a vibration mirror, and the detection signal of a synchronous detection sensor. It is a figure which shows the relationship between the change rate of deflection angle (theta) in a vibration mirror, and time t. It is a block diagram of the drive circuit which modulates a light source unit semiconductor laser. FIG. 21 is an explanatory diagram when the phase of an arbitrary pixel is shifted in the drive circuit of FIG. 20. It is a figure which shows the correction amount of the main scanning position in each pixel according to the main scanning position at the time of modulating with a single frequency. It is a figure which shows the relationship between the reflective surface of a vibration mirror, and a reflective state. It is the schematic which shows the structural example (4) of the optical scanning device based on this invention. 1 is a cross-sectional view illustrating a configuration example of an image forming apparatus according to the present invention.

Explanation of symbols

101, 102, 103, 104, 901 Photosensitive drum 105 Intermediate transfer belt 106 Vibration mirror 107, 108 Light source unit 113 Cylinder lens 120 Scan lens 122, 123, 124, 125 Toroidal lenses 126, 127, 128, 129, 130, 131 , 132 Folding mirror 140, 141 Synchronization detection sensor (light beam detection means)
140a, 140a ', 141a Light receiving surface (light receiving portion)
142 Detection means fixing member 143, 144 Imaging lens 145, 146 Positioning means 154 LED element 155 Photo sensor 156 Condensing lens 201, 202, 203, 204 Light beam 250 Housing body 255 Beam passage frame 257 Side wall 258 Upper cover 259 Transmission window 440 Vibration mirror substrate 441 Vibration mirror surface 442 Torsion beam 443 Vibration plate 444 Reinforcement beam 445 Support member 446, 447 Frame 448 Mounting substrate 449 Circuit substrate 450 Permanent magnet 451 Positioning portion 452 Edge connector portion 453 Holding claw 454 Connector 461 Second substrate 462 First substrate 463 Coil pattern 464 Terminal 465 Patch 470 Yoke 601 Drive pulse generation unit 602 Gain adjustment unit 603 Vibration mirror drive unit (driver)
606 Light source driving means (light source driving unit)
607 Write control unit 608 Pixel clock generation unit 609 Amplitude calculation unit 610 Deflection control means (controller)
611 Pixel clock count measuring means 900 Optical scanning device 902 Charging charger 904 Developing device 905 Cleaning device 907 Paper feed tray 908 Paper feed roller 909 Registration roller pair 910 Fixing device 911 Paper discharge tray 912 Paper discharge roller pair

Claims (9)

Light source means for emitting a light beam;
Light source driving means for modulating and driving the light source means;
Deflection means for deflecting the light beam emitted from the light source means by a vibrating mirror to reciprocate in the main scanning direction;
Deflection control means for controlling driving of the vibrating mirror in the deflection means;
A scanning imaging optical system for guiding the light beam from the deflecting means onto the surface to be scanned;
A plurality of light beam detecting means for detecting passage of the light beam from the deflecting means;
The plurality of light beam detecting means are arranged outside the image forming area in the light beam reciprocating scanning area from the deflecting means, and the light receiving surfaces of the plurality of light beam detecting means are fixed so as to have a desired interval. Detecting means fixing member for
An optical scanning device comprising: A housing having a positioning portion for bringing the detection means fixing member and the scanning imaging optical system into a predetermined arrangement relationship with respect to the center line of the amplitude of reciprocating scanning of the light beam by the deflection means;
2. The optical scanning device according to claim 1, wherein any one of the detection unit fixing member and the scanning imaging optical system is positioned and fixed by a positioning unit of the housing by a positioning unit.   The optical scanning device according to claim 2, wherein an optical element having the largest optical power in the main scanning direction of the scanning imaging optical system has the positioning unit.   The detection means fixing member has a positioning means at an intermediate point between light receiving surfaces of the plurality of light beam detection means, and any one of the optical elements of the scanning imaging optical system is positioned at a central portion in the main scanning direction. The optical scanning device according to claim 2, further comprising means.   The detection means fixing member is positioned on the housing such that an intermediate point between light receiving surfaces of the plurality of light beam detection means is positioned on a center line of amplitude of reciprocal scanning of the light beam by the deflection means. The optical scanning apparatus in any one of -4.   The optical element of any one of the scanning imaging optical system is positioned in the housing so that the optical axis of the optical element coincides with the center line of the amplitude of the reciprocating scanning of the light beam by the deflecting unit. 6. The optical scanning device according to any one of 5 above.   When the distance between the light receiving surfaces of the plurality of light beam detecting means is 2 * Hs and the positional deviation in the main scanning direction of the light receiving surface of any one of the plurality of light beam detecting means is ΔH, The optical scanning device according to claim 1, wherein ΔH / (2 × Hs) × 100 ≦ 0.01 is satisfied. The deflection control means includes
Controlling the deflecting means so that the maximum amplitude of the light beam obtained based on the detection signal detected by the light beam detecting means is constant;
Controlling the deflection means to correct the shift amount of the amplitude center of the light beam obtained based on the detection signal detected by the light beam detection means;
Controlling the deflection means so as to correct the variation in the scanning frequency of the light beam obtained based on the detection signal detected by the light beam detection means;
The optical scanning device according to claim 1, wherein one or two or more controls selected from the above are executed. At least one image carrier;
An image forming apparatus comprising: the optical scanning device according to claim 1, and at least one optical scanning device that scans light including image information on the image carrier.

Images