JP2011118161A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust the bow of a scanning line on a reflecting mirror and to make the reflecting mirror hardly rock against external disturbance in an optical write-in apparatus of an image forming apparatus. <P>SOLUTION: The optical write-in apparatus includes: pressurizing members 13 which pressurize both ends of a mirror 3, which folds the scanning line back to a predetermined position, in the normal line direction with respect to the reflection face and bend the mirror 3; a plunging means 14 which plunges in the direction opposite to that of the pressurizing members 13 to adjust the plunging quantity; and a bracket 15 which holds both members 13, 14 and is provided with supporting points 16 to keep the bent state of the mirror 3 between the pressurized and the plunged positions. The mirror 3 is pressurized by the pressurizing members 13, 13 on both ends, the mirror 3 is originally bent by a predetermined quantity, the center of the mirror 3 is plunged by the plunging means 14, the shape of the mirror 3 is deformed, one of the ends is received by an optical housing 7 (receiving face) while keeping the deformed state, the projected quantity of the end of a driving means 17 is controlled from the back face of the other end of the mirror 3, the tilt quantity of the mirror 3 is adjusted, and the tilt of the scanning line is adjusted. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical writing apparatus mounted on an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these, and an image forming apparatus using the same.

  In an optical writing device used in an electrophotographic image forming apparatus, a scanned light beam (scanning line) may be curved due to surface accuracy of a lens or a mirror used as an optical element. Since an image is formed based on the curved scanning line, it is expressed as a curved line as it is on the image. Further, in the full-color quadruple tandem structure, since the optical writing device has an optical path for each color, there is a problem that the bent shape of the scanning line of each color does not match and the color shift is caused as it is. As a countermeasure for this problem, there is a method in which the scanning lens is bent and adjusted so as to cancel the bending of the generated scanning line.

  This method is based on the premise that there are a plurality of scanning lenses in the optical system after the polygon mirror. However, from the viewpoint of the overall cost of the optical writing apparatus, a method of reducing the number of scanning lenses is often selected. ing. For the optical system of one scanning lens and the like after the polygon mirror, there is already known a method of adjusting the scanning line curve by bending the reflecting mirror in the normal direction with respect to the reflecting surface instead of the lens.

  However, in the conventional method of bending the mirror to adjust the scanning line curve, the mirror is bent with respect to the normal direction of the mirror. In the first place, the reflection mirror is elongated in terms of its characteristics and layout, and both ends are formed in the housing of the optical writing device. In many cases, the mirror is placed on the body (optical housing), and the mirror itself is easily swayed. For this reason, the mirror may sway and resonate in response to vibration from the outside or vibration from the inside of the optical writing device, which may cause an image defect called banding on the image.

  Therefore, for a single reflective mirror, by attaching glass on the back of the mirror or by attaching sheet metal to the side, the cross-sectional moment of the mirror is increased, and the mirror vibrates in the direction normal to the reflective surface. Measures to make it difficult to do were proposed. However, taking this countermeasure against vibration is the same as making the mirror difficult to bend in the normal direction. In other words, there has been a problem that bending adjustment by a mirror and reinforcement against vibration are contradictory.

  Patent Document 1 discloses an optical writing device equipped with a mechanism that adjusts scanning line bending by bending a reflecting mirror for the purpose of correcting scanning line bending. This adjusting mechanism includes a bracket that holds the mirror at both ends and the center, a pressing member that presses the mirror against the holding portions at both ends of the bracket, and an adjusting member that presses the center of the mirror and freely deforms the mirror into irregularities. This is a mirror bending adjustment mechanism. The present invention, which will be described later, is common in that the curvature of the scanning line is adjusted by bending the mirror, but the problem that the mirror tends to vibrate due to disturbance cannot be solved.

  An object of the present invention is to adjust the scanning line curve with a reflection mirror, and to make the mirror more difficult to shake than ever.

  The mirror curvature adjusting mechanism according to the first aspect of the present invention includes a light source, a rotating polygon mirror that scans the light beam from the light source in the main scanning direction, and a beam light scanned by the rotating polygon mirror. A mirror curvature adjusting mechanism used in an optical writing device comprising an optical element leading to the position of the optical mirror and an optical housing in which the polygon mirror and the optical element are arranged, and is supported at both longitudinal ends of the optical housing. A reflecting mirror, a pressing member that presses the reflecting mirror in a direction normal to the reflecting surface, and bends the reflecting mirror by a certain amount, and is located at the center in the longitudinal direction of the reflecting mirror from both end support positions of the reflecting mirror. And a pressing means that can push the reflecting mirror in a direction opposite to the direction curved by the pressing member to adjust a bending amount of the reflecting mirror, and the pushing means is attached to the reflecting mirror. Characterized in that it is a constant.

  According to a second aspect of the present invention, in the mirror curvature adjusting mechanism according to the first aspect, the pushing means is arranged in the optical housing.

  According to a third aspect of the present invention, in the mirror curvature adjusting mechanism according to the first aspect, one end side of the reflection mirror is supported by the optical housing, and the reflection mirror is driven by a driving unit attached to the other end of the reflection mirror. And the pushing means is disposed on a bracket that holds the reflecting mirror at both ends in the longitudinal direction of the reflecting mirror inside the support position of the reflecting mirror to the optical housing. Features.

According to a fourth aspect of the present invention, in the mirror bending adjustment mechanism according to any one of the first to third aspects, the pushing means is moved from the end of the reflecting mirror to the longitudinal direction of the reflecting mirror as follows: Inequalities (where L is the length of the reflecting mirror in the longitudinal direction, and X is the distance from the end of the reflecting mirror to the pushing means)
(1/4) L <X <(2/4) L or (2/4) L <X <(3/4) L
It is characterized by being arranged at a position where is established.

  According to a fifth aspect of the present invention, in the mirror curvature adjusting mechanism according to any one of the first to fourth aspects, a plurality of the pushing means are provided.

  According to a sixth aspect of the present invention, in the mirror curvature adjusting mechanism according to any one of the first to fifth aspects, the pushing means is fixed to the reflecting mirror with an adhesive.

  According to a seventh aspect of the present invention, in the mirror curvature adjusting mechanism according to the sixth aspect, the adhesive is a photo-curing (UV) adhesive.

  An optical writing apparatus according to an eighth aspect is characterized in that the mirror curvature adjusting mechanism according to any one of the first to seventh aspects is mounted for at least one reflection mirror.

  An image forming apparatus according to a ninth aspect includes the optical writing apparatus according to the eighth aspect.

  According to the present invention, the pushing member for adjusting the curvature of the reflecting mirror located at the center of the reflecting mirror is fixed to the reflecting mirror so that the position becomes a node of the vibration state, and the natural frequency of the reflecting mirror is greatly increased. In the structure in which the scanning line bend is adjusted with the reflection mirror, the reflection mirror can be made more difficult to shake than ever with disturbances such as vibration.

1 is a conceptual cross-sectional view showing a schematic internal configuration example of a digital color writing processing system which is an example of a system using an image forming apparatus according to the present invention. 1 is a conceptual cross-sectional view showing an outline of a digital color machine which is an example of an image forming apparatus according to the invention. Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the bending adjustment mechanism by the reflection mirror Conceptual diagram for explaining the adjusting mechanism in which the mirror and the pushing means are fixed Conceptual diagram for explaining the adjusting mechanism in which the mirror and the pushing means are fixed Conceptual diagram for explaining the adjusting mechanism in which the mirror and the pushing means are fixed Conceptual diagram for explaining the adjusting mechanism in which the mirror and the pushing means are fixed Conceptual diagram for explaining the adjusting mechanism in which the mirror and the pushing means are fixed Conceptual diagram for explaining the adjusting mechanism in which the mirror and the pushing means are fixed The conceptual perspective view which expands and shows the fixed state of a mirror and pushing means

  An embodiment of the present invention will be described. In the present invention, the mechanism for freely bending the reflecting mirror and adjusting the scanning line bending has the following characteristics. That is, after adjusting the curvature of the reflection mirror, the push member for adjusting the curvature is fixed to the reflection mirror so that the position becomes a node of the vibration state, and the natural frequency of the reflection mirror It becomes the composition which raises greatly. In other words, in the present invention, the natural frequency of the reflection mirror can be significantly increased, and therefore the reflection mirror is less likely to shake with respect to disturbances such as vibration in the structure in which the scanning line bending is adjusted by the reflection mirror.

  Therefore, in the optical writing device according to the present invention, a light source, a rotating polygon mirror that scans the beam light from the light source in the main scanning direction, an optical element that guides the beam light scanned by the rotating polygon mirror to a predetermined position, In an optical writing device including an optical housing in which a polygon mirror and an optical element are arranged, a reflecting mirror supported at both ends in the longitudinal direction with respect to the optical housing, and the reflecting mirror is pressed in a normal direction with respect to the reflecting surface, Mirror bending having a pressing member for bending the mirror by a certain amount, and a pressing means which is located in the center in the longitudinal direction from the both-end support positions of the reflecting mirror and is pushed in the direction opposite to the bending direction by the pressing member and can adjust the bending amount of the mirror. The adjusting mechanism includes a pushing means fixed to a mirror. As a result, the adjustment pushing means of the mirror bending adjustment mechanism is fixed to the mirror to take measures against vibration suppression. Further, by adopting this method, the position where the mirror feed screw is arranged can be made a node, and the natural frequency can be increased.

  Further, according to the present invention, the pushing means capable of adjusting the bending amount of the mirror is arranged in the optical housing, and the pushing means can be arranged not only in the bracket or the like but also in the optical housing.

  Further, according to the present invention, one end side of the mirror is supported by the optical housing, and the tilt of the mirror can be controlled by the driving means attached to the other end portion. The pushing means capable of adjusting the amount of bending of the mirror is disposed on a bracket that holds the mirror at both ends in the longitudinal direction inside the optical housing support position of the mirror. The anti-vibration measure of the bending adjustment mechanism in which the adjustment pushing means is arranged on the bracket is intended. Even with the adjustment mechanism when holding the mirror with a bracket, etc., the mirror itself vibrates, causing defects such as banding in the image, so by fixing the mirror pushing means and the mirror, The position is a node in the longitudinal direction of the mirror, which increases the natural frequency and makes it possible to obtain a good image. In addition, by attaching a driving means such as a pulse motor to one end, it is possible to adjust the mirror inclination and to adjust the inclination of the scanning line simultaneously with the bending of the scanning line.

In the present invention, the pushing means is arranged at a position where the following inequality is established from the mirror end with respect to the longitudinal direction of the mirror. That is, when the length L in the longitudinal direction of the mirror and the distance X from the mirror end to the pushing means,
(1/4) L <X <(2/4) L or (2/4) L <X <(3/4) L
And Thus, by placing the pushing means at the position where the above formula is established with respect to the longitudinal direction of the mirror, it is possible to prevent the vibrations of the left and right mirrors from strengthening each other from the fixed position.

  Further, in the present invention, a plurality of pushing means are arranged in one mirror bending adjustment mechanism, and the bending state of the mirror can be adjusted more finely. Further, by adopting this configuration, by fixing each position and the mirror, it is possible to make the position a node, and further increase of the natural frequency can be expected.

  In the present invention, the pushing means is fixed to the mirror with an adhesive. In this case, after adjusting the curvature of the mirror by the pushing means, an adhesive can be used at the contact portion between the mirror and the pushing means, and it is possible to achieve fixing with low cost and excellent layout. The adhesive is preferably a photocurable (UV) adhesive. Fixing can be achieved by attaching a UV adhesive in advance to the contact portion between the mirror and the pushing means, and then applying light after adjustment to harden the light. In addition, when the adhesive is applied and hardened after adjustment, there is a risk of changing the adjustment state of the pushing means when the adhesive is applied to the contact portion between the mirror and the pushing means. Fixing can be achieved without changing the state.

  Furthermore, the optical writing device of the present invention can be configured such that the mirror curvature adjusting mechanism as described above is mounted on one or a plurality of mirrors. By mounting the above mirror curvature adjusting mechanism on the mirror of each station, it is possible to provide an optical writing device that has good scanning lines and is resistant to vibration. In addition, it is possible to reduce the cost by selecting only a portion that easily shakes against vibration. If such an optical writing device is mounted on an image forming apparatus, an image forming apparatus with small color misregistration and hardly causing banding can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to the illustrated image forming apparatus, and can be applied to various apparatuses that perform image formation.

  FIG. 1 and FIG. 2 are diagrams for explaining the outline of a digital color machine and the whole of an optical writing / scanning apparatus as an object of the present invention. FIG. 1 shows a schematic internal configuration example of a digital color writing processing system which is an example of a system using an image forming apparatus according to the present invention. As shown in the figure, this system has a reflection mirror on the side surface of a regular polygon, and equiangular movement of the scanning beam by polygon mirrors 1a and 1b and polygon mirrors 1a and 1b that deflect and scan laser light by high-speed rotation. Fθ lenses 2a to 2d for converting the laser beam to constant linear motion, reflection mirrors 3a to 3d and 4a to 4d for guiding laser beams to the photoreceptors 6a to 6d for forming an image, and an optical housing 7 in which these optical elements are arranged It consists of dust-proof glasses 5a to 5d for preventing dust and the like from dropping onto the upper housing lid 8 for sealing the optical housing 7.

  FIG. 2 schematically shows a digital color machine 10 which is an example of an image forming apparatus according to the present invention. In this figure, the writing laser light emitted from the above-described optical system is indicated by reference numerals 9a to 9d. In the figure, reference numeral 11 is an intermediate transfer belt, and 12 is a paper feed tray. An arrow A in the figure indicates the driving direction of the intermediate transfer belt 11.

  3A to 3G are diagrams illustrating a bending adjustment mechanism using the reflection mirrors 3a to 3d and 4a to 4d. In the following detailed description, the reflecting mirror is simply referred to as mirror 3 unless particularly required.

  FIG. 3A and FIG. 3B show an example of a bending adjustment mechanism using a reflection mirror. The mirror 3 that folds the scanning line to a predetermined position, both ends of the mirror 3 are pressed in the normal direction against the reflecting surface, and the pressing member 13 such as a leaf spring that forcibly bends the mirror 3 is pushed in the direction opposite to the pressing member 13. The pressing means 14 that can adjust the pressing amount, the pressing member 13 and the pressing means 14 are held, and the bracket 15 is provided with a fulcrum 16 for holding the curved state of the mirror 3 between the pressing position and the pressing position. Is done.

  As shown in FIG. 3C, the mirror 3 is pressed by the pressing members 13 and 13 at both ends, and the mirror 3 is initially bent by a certain amount (the upward convex direction in the figure). From this state, the center of the mirror 3 is pushed by pushing means such as a screw, and the shape of the mirror 3 is deformed from convex to concave by the pushing amount. While maintaining this mirror deformed state, one end is received by the optical housing 7 (receiving surface) as a fulcrum, and the protruding amount of the tip of the driving means 17 such as a pulse motor is controlled from the mirror back of the other end. Thus, a mechanism for adjusting the tilt amount of the mirror 3 and adjusting the scan line tilt is obtained.

  This mechanism can adjust the scanning line inclination without changing the bending shape while adjusting the bending of the scanning line with a single mirror 3 and has an excellent performance and cost.

  In the present embodiment, the bending adjustment mechanism in which the fulcrum of the bracket 15 is arranged on the reflection surface side of the mirror 3 and the pressing member 13 and the pushing means 14 are arranged on the surface side opposite to the reflection surface is shown, but as shown in FIG. The same function can be achieved by disposing the pressing member 13 on the reflecting surface side of the mirror 3 and the fulcrum of the bracket 15 and the pushing means 14 on the surface side opposite to the reflecting surface.

  FIGS. 3E and 3F show an example of an adjusting mechanism in which the bracket 15 is not provided and the pressing member 19 and the pressing means 14 are arranged in the optical housing 15. The mirror 3 is supported at both ends by receiving surfaces on the optical housing 7, and a pressing member 19 such as a leaf spring is disposed outside (both ends) from the position where the mirror 3 is supported. The receiving point is a fulcrum, the pressing point by the pressing member 19 is a force point, and the mirror 3 is bent by a certain amount. The pressing member 19 is fixed on the optical housing 7 by screwing or the like. Then, the center of the mirror 3 is pushed in the direction opposite to the direction in which the pressing member 19 is curved by the pushing means 14 such as a screw held by the plate member 20 fixed to the optical housing 7 near the center of the mirror 3. The curvature of the mirror 3 is adjusted to be uneven.

  As shown in FIG. 3G, the bending adjustment can be similarly performed by using a method in which a nut 21 is press-fitted into the optical housing 7 and the pushing means 14 is disposed in the nut 21 without using a plate material. Alternatively, a screw hole may be directly cut in the optical housing 7 and held there.

  4A to 4F are diagrams illustrating a specific adjustment mechanism in which the mirror 3 and the pushing means 14 are fixed. 4A is a side view of the mirror adjustment mechanism, and FIG. 4B is a perspective view. The bending state of the mirror 3 is adjusted by being pushed in from the back surface of the mirror 3 by the pushing means 14 (specifically, the screw 18 at the tip). However, when vibration is applied to the mirror 3, the screw 18 is provided at the center of the mirror 3. In the figure with no oscillating in the right direction, the left side in the figure without the screw 18 is free. Therefore, the left side of the figure has a structure that swings.

  The mirror 3 vibrates in a complicated mode because both ends are received by the optical housing 7 while supporting the bracket 15 for adjusting the curvature, the pressing member 13 and the pressing means 14, but in the longitudinal direction of the mirror 3. In comparison, the vibration level is higher near the center than at the end. For this reason, by fixing the screw 18 of the push-in means 14 and the mirror 3 with the adhesive 22 or the like at the center of the mirror 3 that is most likely to be shaken, the position of the mirror 3 is set as a place where it cannot be shaken, that is, a node. It is rising.

  An example is shown in FIG. 4C. The mirror 3 is freely curved by the amount of pressing of the screw 18 on the back surface of the mirror 3. The contact portion between the back surface of the mirror 3 and the tip of the screw 18 is fixed with an adhesive 22 (of course, other fixing means can be adopted). As a result, even if vibration is applied to the mirror 3, the center is a node, so that a structure that does not shake can be obtained, and the natural frequency of the mirror 3 can be increased.

  When fixing with the adhesive 22 etc., the contact part of the pushing means 14 and the mirror 3 changes before and after adjustment. For this reason, the fixing is preferably performed after the curvature of the mirror 3 is adjusted. Further, since the screw 18 is fastened to the bracket 15, the screw 18 does not move and the mirror 3 does not vibrate. The screw 18 can be further fixed by attaching a locking agent 23 (screw locking agent) to the screw 18 or the female screw of the bracket 15.

In addition, although the example which has arrange | positioned the pushing means 14 to the longitudinal direction center of the mirror 3 was shown, the example which has arranged the pushing means in the position of the following conditions is shown to FIG. 4D. The natural frequency can be increased by setting the center of the mirror 3 as a node, but the length of the mirror 3 from the center fixed position (node) to the left end and the right end is the same. For this reason, the natural frequencies on the left side and the right side from the center may be the same or close to each other. Although the value is higher than the natural frequency of the original mirror, if resonance occurs at that natural frequency, the left and right natural frequencies are the same or close to each other, which may intensify each other's vibrations. . Therefore, the left and right natural frequency values can be shifted by shifting the fixed position from the center as in the following conditions. Thereby, it is possible to prevent mutual vibrations from being strengthened at the left and right portions of the mirror from the fixed position. However, it is desirable to select the position of the pushing means 14 from the vibration applied to the mirror 3 and the situation of the scanning line bending because the pushing means 14 is arranged at the center so that the scanning line bending can be adjusted with high accuracy.
[conditions]
When the length in the longitudinal direction of the mirror is L and the distance from the mirror end to the pushing means is X,
(1/4) L <X <(2/4) L
Or (2/4) L <X <(3/4) L
And

  Next, FIG. 4E shows an embodiment in which a plurality of pushing means are provided for the bending adjustment mechanism of one mirror 3. By fixing the plurality of pushing means 14 and the mirror 3, each position can be set as a node, which is a further measure against vibration. Further, in adjusting the scanning line bending, the scanning line bending can be adjusted more finely by adjusting with a plurality of pushing means.

  An example in which a UV curable adhesive is used as the adhesive is shown in FIG. 4F. By using an adhesive to make the center of the mirror 3 a node, the mirror 3 and the pushing means 14 can be fixed. However, when the adhesive 22 is applied to the contact portion between the pushing means 14 and the mirror 3 after adjustment. It may be necessary to be careful not to change the adjustment state. Therefore, a UV curable adhesive is attached to the contact portion between the pushing means 14 and the mirror 3 at the time of assembly before adjustment, etc., and UV is irradiated after adjustment, so that the state after adjustment is fixed without risk. Can be planned.

1a, 1b: polygon mirrors 2a-2d: fθ lenses 3a-3d, 4a-4d: reflection mirrors 5a-5d: dustproof glass 6a-6d: photoconductor 7: optical housing (receiving surface)
8: Upper lids 9a to 9d: Writing laser beam 10: Digital color machine 11: Intermediate transfer belt 12: Paper feed tray 13: Pressing member 14: Pushing means 15: Bracket 16: Support point 17: Driving means 18: Screw 19: Press member 20: Plate material 21: Nut 22: Adhesive

JP 2006-017881 A

Claims (9)

A light source, a rotating polygon mirror that scans the light beam from the light source in the main scanning direction, an optical element that guides the beam light scanned by the rotating polygon mirror to a predetermined position, and the polygon mirror and the optical element are arranged. A mirror curvature adjusting mechanism used in an optical writing device including an optical housing,
Reflecting mirrors supported at both longitudinal ends of the optical housing;
A pressing member that presses the reflecting mirror in a direction normal to the reflecting surface and curves the reflecting mirror by a certain amount;
There is a pushing means that is located at the center in the longitudinal direction of the reflecting mirror from the both-end supporting position of the reflecting mirror and that can adjust the amount of bending of the reflecting mirror by pushing the reflecting mirror opposite to the direction curved by the pressing member. And
A mirror curvature adjusting mechanism, wherein the pushing means is fixed to the reflecting mirror. 2. The mirror curvature adjusting mechanism according to claim 1, wherein the pushing means is disposed in the optical housing. The mirror curvature adjusting mechanism according to claim 1, wherein one end side of the reflection mirror is supported by the optical housing, and the inclination of the reflection mirror can be controlled by a driving unit attached to the other end of the reflection mirror.
A mirror curvature adjusting mechanism, wherein the pushing means is arranged on a bracket that holds the reflecting mirror at both ends in the longitudinal direction of the reflecting mirror, inside the position where the reflecting mirror is supported on the optical housing. The mirror bending adjustment mechanism according to any one of claims 1 to 3, wherein the pushing means is moved from the end of the reflecting mirror to the longitudinal direction of the reflecting mirror from the following inequality (where L is the The length in the longitudinal direction of the reflecting mirror, X is the distance from the end of the reflecting mirror to the pushing means)
(1/4) L <X <(2/4) L or (2/4) L <X <(3/4) L
A mirror curvature adjustment mechanism characterized in that the mirror curvature adjustment mechanism is arranged at a position where is established. The mirror curvature adjustment mechanism according to any one of claims 1 to 4, wherein the mirror curvature adjustment mechanism includes a plurality of the pushing means. 6. The mirror curvature adjusting mechanism according to claim 1, wherein the pushing means is fixed to the reflection mirror with an adhesive. 7. The mirror curvature adjusting mechanism according to claim 6, wherein the adhesive is a photo-curing (UV) adhesive. 8. An optical writing device comprising the mirror bending adjusting mechanism according to claim 1 mounted for at least one reflecting mirror. An image forming apparatus comprising the optical writing device according to claim 8.