JP6130803B2 - Optical scanning device and image forming apparatus including the optical scanning device - Google Patents

Description

  The present invention relates to an optical scanning device and an image forming apparatus including the optical scanning device.

  Conventionally, optical scanning devices used in laser printers, copying machines, and the like are known. This optical scanning apparatus is configured to deflect laser light emitted from a light source by scanning a polygon mirror and scan it on a surface to be scanned. An imaging lens is disposed between the polygon mirror and the surface to be scanned. The imaging lens forms an image of the light deflected by the polygon mirror on the surface to be scanned. The polygon mirror and the lens are accommodated in one casing.

  In this type of optical scanning device, there is a problem that the scanning light is bent when the lens is bent in the sub-scanning direction when viewed from the optical axis direction. In order to solve this problem, a technique for correcting the deflection of the lens in the sub-scanning direction has been proposed (for example, see Patent Document 1). In this optical scanning device, a deflection correction mechanism is provided in a holder that holds a lens. The holder supports the lens from the seating surface side, and is fixed to the housing. The deflection correction mechanism has three springs and positioning screws. The positioning screw protrudes from the center of the holder in the main scanning direction. The tip of the screw is in contact with the seating surface of the lens. The plurality of springs are in contact with the surface opposite to the seating surface of the lens and are configured to press the lens against the tip of the screw. The deflection of the lens is corrected by adjusting the protruding amount of the screw.

JP 2013-80048 A

However, in the conventional optical scanning device shown in Patent Document 1, since the lens is attached to the housing via the holder (lens holding member), the assembly error of the lens with respect to the lens holding member and the lens with respect to the housing by integrating the assembly error of the holding member, there is a problem that it is difficult to ensure the assembling accuracy of the lens with respect to the casing.

  On the other hand, it is conceivable to increase the processing accuracy of the lens holding member and the lens. However, in this case, there is a problem that the processing cost increases.

  The present invention has been made in view of the above points, and an object of the present invention is to devise a configuration of an optical scanning device including a lens holding member having a deflection correction mechanism for an imaging lens. Thus, the assembly accuracy of the imaging lens with respect to the housing is improved with an inexpensive configuration.

  An optical scanning device according to the present invention includes a light source unit that emits laser light, a deflector that reflects and deflects the laser light emitted from the light source unit in the main scanning direction, and the laser beam that has been deflected and scanned. An imaging lens that forms an image on the surface to be scanned, a housing that houses the deflector and the imaging lens, and correction that the imaging lens bends in the sub-scanning direction when viewed from the optical axis direction. A lens holding member having a correction mechanism.

The lens holding member extends in the main scanning direction facing the other side opposite to the one side in the optical axis direction of the imaging lens, and has a vertical wall having an opening through which light passes, An upper flange that protrudes from the upper end of the vertical wall in the optical axis direction and faces the upper side of the imaging lens in the sub-scanning direction, and protrudes from the lower end of the vertical wall to the opposite side of the imaging lens A lower flange portion, and the correction mechanism is screwed into a screw hole formed in a central portion of the upper flange portion in the main scanning direction, and a tip portion thereof is an upper side in the sub-scanning direction of the imaging lens. And an adjustment screw that is in contact with the lower flange portion, and is fixed to a central portion of the lower flange portion in the main scanning direction, and presses the lower side surface of the imaging lens in the sub-scanning direction to the upper side in the sub-scanning direction. A biasing member that presses the upper side against the tip of the adjusting screw. , At both ends in the main scanning direction definitive the lower surface of the sub-scanning direction of the imaging lens, the first contact portion directly in contact with the housing is formed, the optical axis of the one of the imaging lens At both ends in the main scanning direction definitive on the side surface, the second contact portion housing directly in contact is formed, the imaging lens, directly above the first and second contact portions to the housing those The fixing member that fixes the lens holding member to the casing in a state where the positioning in the sub-scanning direction and the optical axis direction with respect to the casing is performed and the imaging lens is positioned. Is further provided.

  According to this configuration, since the deflection of the imaging lens in the sub-scanning direction is corrected by the correction mechanism provided in the lens holding member, it is possible to prevent the scanning line from being curved on the surface to be scanned.

  In addition, the first and second contact portions formed on the imaging lens directly contact the housing, whereby the imaging lens is positioned in the sub-scanning direction and the optical axis direction. In this way, by positioning the imaging lens directly against the housing, the positioning accuracy of the imaging lens with respect to the housing is improved without increasing the processing accuracy of the imaging lens and the housing. Can be made. Therefore, it is possible to suppress the positional deviation of the scanning light on the surface to be scanned with an inexpensive configuration.

  The imaging lens has a first engaging portion, and the holder has a second engaging portion for positioning the imaging lens in the main scanning direction by engaging with the first engaging portion. Preferably it is formed.

  According to this configuration, the first engagement portion formed on the imaging lens is engaged with the second engagement portion formed on the holder, whereby the imaging lens is positioned in the main scanning direction. Here, the first engaging portion is formed at the center of the imaging lens in the main scanning direction. Therefore, the thermal expansion characteristics of the imaging lens can be made symmetric with respect to the central portion in the main scanning direction. As a result, it is possible to suppress the bending and displacement of the scanning light imaged on the surface to be scanned by the imaging lens.

  An image forming apparatus according to the present invention includes the optical scanning device.

  According to this configuration, the image quality can be improved with an inexpensive configuration.

  According to the present invention, in an optical scanning device including a lens holder having an imaging lens correction mechanism, the assembly accuracy of the imaging lens with respect to the housing can be improved with an inexpensive configuration.

FIG. 1 is a schematic diagram illustrating an image forming apparatus including an optical scanning device according to an embodiment. FIG. 2 is a schematic view showing an optical scanning device. FIG. 3 is a schematic diagram linearly showing the optical path from the light source unit to the polygon mirror. FIG. 4 is a perspective view showing the lens holder fixed to the housing. 5 is a cross-sectional view taken along the line VV in FIG. FIG. 6 is an enlarged view showing a central portion in the main scanning direction of FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a view corresponding to FIG. 5 showing another embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

<Embodiment>
FIG. 1 shows an image forming apparatus 1 according to the embodiment. The image forming apparatus 1 is a tandem color printer, and includes an intermediate transfer belt 7, a primary transfer unit 8 and a secondary transfer unit 9, a fixing unit 11, an optical scanning device 15, and four image forming units. Units 16a to 16d and first to fourth paper transport units 21 to 24 are provided.

  A paper feed cassette 3 is disposed in the lower part of the main body 2 of the image forming apparatus 1. The paper feed cassette 3 stores and accommodates paper (not shown) such as cut paper before printing. The sheets are separated and sent one by one toward the upper left of the sheet feeding cassette 3 in FIG.

  The first paper transport unit 21 is provided on the side of the paper feed cassette 3. The first paper transport unit 21 is disposed along the left side surface of the main body 2. The first paper transport unit 21 receives the paper sent from the paper feed cassette 3 and transports the paper along the left side surface of the main body 2 to the upper secondary transfer unit 9.

  A manual paper feed unit 5 is provided on the right side of the paper feed cassette 3. In the manual sheet feeder 5, paper of a size that is not in the paper cassette 3, thick paper, an OHP sheet, or the like is placed. A second paper transport unit 22 is provided on the left side of the manual paper feed unit 5. The second paper transport unit 22 extends substantially horizontally from the manual paper feed unit 5 to the first paper transport unit 21 and joins the first paper transport unit 21. Then, the second paper transport unit 22 receives the paper sent from the manual paper feed unit 5 and transports it to the first paper transport unit 21.

The optical scanning device 15 is disposed above the second paper transport unit 22. Here, the image forming apparatus 1 receives image data transmitted from the outside. The image data is stored in a temporary storage unit (not shown) and then sent to the optical scanning device 15 as necessary. The optical scanning device 15 irradiates the image forming units 16 a to 16 d with laser light controlled based on the image data. The image forming units 16 a to 16 d are provided above the optical scanning device 15. Each of the image forming units 16a to 16d has photosensitive drums 10a to 10d, respectively. Chargers 20a to 20d, developing devices 30a to 30d, and cleaning devices 40a to 40d are provided for the respective photosensitive drums 10a to 10d. The cleaning devices 40a to 40d are provided for cleaning the peripheral surfaces of the photosensitive drums 10a to 10d.

  An endless intermediate transfer belt 7 is provided above each of the image forming units 16a to 16d. The intermediate transfer belt 7 is wound around a plurality of rollers and is rotationally driven by a driving device (not shown).

  As shown in FIG. 1, the four image forming units 16a to 16d are arranged in a line along the intermediate transfer belt 7, and respectively form yellow, magenta, cyan, or black toner images. That is, in each of the image forming units 16a to 16d, the optical scanning device 15 irradiates the peripheral surfaces of the photosensitive drums 10a to 10d with laser light to form an electrostatic latent image of the original image, and the developing devices 30a to 30d Each color toner image is formed by developing the electrostatic latent image.

  The primary transfer portions 8a to 8d are respectively disposed above the image forming units 16a to 16d. The primary transfer portions 8 a to 8 d include primary transfer rollers 80 a to 80 d that primarily transfer the toner images formed by the image forming units 16 a to 16 d to the surface of the intermediate transfer belt 7. A transfer bias is applied to the primary transfer rollers 80a to 80d from a transfer bias power source (not shown). The toner images of the image forming units 16a to 16d are transferred to the intermediate transfer belt 7 at a predetermined timing by a transfer bias applied to the primary transfer rollers 80a to 80d. Thus, a color toner image is formed on the surface of the intermediate transfer belt 7 by superposing four color toner images of yellow, magenta, cyan, and black.

  The secondary transfer unit 9 has a secondary transfer roller 18 disposed on the left side of the intermediate transfer belt 7. A transfer bias is applied to the secondary transfer roller 18 by a transfer bias power source. The secondary transfer roller 18 sandwiches the paper P with the intermediate transfer belt 7. Thus, the toner image on the intermediate transfer belt 7 is transferred onto the paper P by the transfer bias applied to the secondary transfer roller 18.

  The fixing unit 11 is provided above the secondary transfer unit 9. Between the secondary transfer unit 9 and the fixing unit 11, a third paper transport unit 23 that transports the paper P onto which the toner image has been secondarily transferred to the fixing unit 11 is formed.

  The fixing unit 11 includes a heating roller 182 and a pressure roller 181 that rotate. The fixing unit 11 holds the paper P between the heating roller 182 and the pressure roller 181 so that the toner image transferred to the paper P is heated and pressed to be fixed on the paper P.

  A branch portion 27 is provided above the fixing portion 11. The sheet P discharged from the fixing unit 11 is discharged from the branching unit 27 to the sheet discharging unit 28 formed on the upper part of the image forming apparatus 1 when double-sided printing is not performed. The discharge port portion from which the paper P is discharged from the branch portion 27 toward the paper discharge portion 28 functions as a switchback portion 29. When performing duplex printing, the switchback unit 29 switches the transport direction of the paper P discharged from the fixing unit 11.

-Details of optical scanning device-
As shown in FIG. 2, the optical scanning device 4 has a housing 43. A polygon mirror 44 is disposed in the housing 43. In the present embodiment, the polygon mirror 44 has a regular hexagonal shape having six reflecting surfaces 44a on the side surface, and is rotated at a predetermined speed by a motor (not shown).

  FIG. 3 is a schematic diagram linearly showing the incident optical system 70 from the light source unit 40 of the optical scanning device 4 to the reflection surface 44 a of the polygon mirror 44. The light source unit 40 includes four light sources 40a, 40b, 40c, and 40d. The four light sources 40a to 40d are arranged at intervals in the sub-scanning direction (the rotational axis direction of the polygon mirror 44 and the vertical direction in the figure). The light sources 40a to 40d are configured by laser diodes, and emit light beams (laser beams) D1 to D4 that are optically modulated based on image signals. Between the light sources 40a to 40d and the polygon mirror 44, four collimator lenses 41a to 41d provided corresponding to the respective light sources 40a to 40d and beam lights D1 to D4 that have passed through the collimator lenses 41a to 41d are predetermined. Apertures 60a to 60d having optical path widths of 2 and a cylinder lens 42 through which the light beams D1 to D4 pass after passing through the apertures 60a to 60d are disposed.

  Returning to FIG. 2, the fθ lens 45, the first mirrors 46a to 46d, the second mirrors 47 to 49, and the first mirrors are arranged on the optical paths of the beam lights D1 to D4 from the polygon mirror 44 to the photosensitive drums 10a to 10d. Three mirrors 50 are arranged.

  The scanning operation of the light beams D1 to D4 by the optical scanning device 4 configured as described above will be described. First, the beam lights D1 to D4 respectively emitted from the light source units 40a to 40d are made into a substantially parallel light flux by the collimator lenses 41a to 41c, and have a predetermined optical path width by the apertures 60a to 60d. Next, the beam lights D <b> 1 to D <b> 4 that have become substantially parallel light beams enter the cylinder lens 42. The light beams D1 to D4 incident on the cylinder lens 42 are in the state of a parallel light beam as they are in the main scanning section (section with the sub-scanning direction as the normal line), and are in the sub-scanning section (section with the main scanning direction as the normal line). Are converged and emitted to form a line image on the reflection surface 44 a of the polygon mirror 44. At this time, in order to facilitate the optical path separation of the four light beams D1 to D4 deflected by the polygon mirror 44, these light beams D1 to D4 are reflected on the reflecting surface when viewed in the sub-scan section (see FIG. 3). The light incidents on the 44a at different angles.

  The beam lights D1 to D4 incident on the polygon mirror 44 are scanned at a constant angular velocity by the polygon mirror 44 and then converted to a constant velocity scan by the fθ lens 45. The beam lights D1 to D4 that have passed through the fθ lens 45 are respectively reflected by the first mirrors 46a to 46d, and then guided to the surfaces 10p to 10s of the photosensitive drums 10a to 10d to be scanned.

  Next, the attachment structure of the fθ lens 45 to the housing 43 will be described. The fθ lens 45 extends in the main scanning direction. The fθ lens 45 is inclined so as to be along the sub-scanning direction when viewed from the main scanning direction (see FIG. 5). Both end portions of the fθ lens 45 are supported by a pair of support block portions 43k integrally formed on the bottom wall portion of the housing 43 (see FIG. 4). The support block portion 43 k constitutes a part of the housing 43. The fθ lens 45 is held by a holder 100 as a lens holding member. The holder 100 is arranged so as to extend in the main scanning direction and cover the fθ lens 45 from above.

  As shown in FIG. 5, the holder 100 has a first vertical wall portion 100a, an upper flange portion 100b, a lower flange portion 100c, and a second vertical wall portion 100d. The second vertical wall portion 100d is disposed on one side of the fθ lens 45 in the optical axis direction, and the first vertical wall portion 100a is disposed on the other side of the fθ lens 45 in the optical axis direction. Both vertical wall portions extend in the main scanning direction. A substantially rectangular opening 100f extending in the main scanning direction is formed in the first vertical wall 100a. The light that has passed through the fθ lens 45 is guided to the first mirrors 46a to 46d (only the first mirror 46a is shown in FIG. 4) through the opening 100f. An engagement hole 100k (see FIGS. 5 and 6) is formed at the center of the second vertical wall portion 100d in the main scanning direction. An engagement protrusion 45f formed on the fθ lens 45 is engaged with the engagement hole 100k. The engagement protrusion 45f is formed at the upper end of the fθ lens 45 and protrudes from the center in the main scanning direction to one side in the optical axis direction. The engagement θ 45 is engaged with the engagement hole 100 k of the holder 100, whereby the fθ lens 45 is positioned in the main scanning direction.

  The upper flange portion 100b protrudes from the upper end portion of the first vertical wall portion 100a to one side in the optical axis direction and is connected to the upper end portion of the second vertical wall portion 100d. A set screw 106 is provided at the center of the upper flange portion 100b in the main scanning direction. The set screw 106 passes through the upper flange portion 100b and protrudes toward the fθ lens 45 side. The tip of the set screw 106 is in contact with the upper end surface of the fθ lens 45.

  The lower flange portion 100c protrudes from the lower end portion of the first vertical wall portion 100a to the other side in the optical axis direction. A leaf spring 104 is fixed to the lower flange portion 100c with a bolt 105. The leaf spring 104 is configured to abut against the lower surface of the fθ lens 45 and press the lens 45 against the tip of the set screw 106. Then, by rotating the set screw 106 and adjusting the amount of protrusion, the deflection of the fθ lens 45 in the sub-scanning direction (the central portion of the fθ lens 45 in the main scanning direction is one side in the sub-scanning direction when viewed from the optical axis direction). (Deflection that bulges out) can be corrected. The set screw 106 and the leaf spring 104 constitute a correction mechanism 150 that corrects the deflection of the fθ lens 45 in the sub-scanning direction.

As shown in FIG. 7, the fθ lens 45 is positioned by directly contacting the housing 43. One side surface 45 a of the fθ lens 45 in the sub-scanning direction is in contact with the protruding seat portion 43 c of the housing 43. The protruding seat portion 43 c is formed on the lens holding surface 43 b of the support block portion 43 k of the housing 43. Abutting portion 45c on the projecting seat portion 43 c of the one side surface 45a of the fθ lens 45 constitutes a first contact portion.

  On one side surface 45b of the fθ lens 45 in the optical axis direction, a pair of projecting portions 45d arranged at intervals in the sub-scanning direction is formed. The front end surface of each protrusion 45 d is in contact with the inclined surface 43 a of the housing 43. The inclined surface 43a is inclined along the sub-scanning direction. Each said protrusion part 45d comprises the 2nd contact part.

  As described above, in the above-described embodiment, the portion 45c (first contact portion) of the one side surface 45a of the fθ lens 45 in the sub-scanning direction and the protruding portion 45d (first portion 45b) formed on the one side surface 45b in the optical axis direction. When the second contact portion) directly contacts the housing 43, the fθ lens 45 is positioned relative to the housing 43 in the sub-scanning direction and the optical axis direction.

 In this way, by positioning the fθ lens 45 directly in contact with the housing 43, the fθ lens 45 is positioned relative to the housing 43 without increasing the processing accuracy of the fθ lens 45 and the housing 43. Accuracy can be improved. Therefore, it is possible to suppress the positional deviation of the scanning light on the surface of the photosensitive drums 10a to 10d with an inexpensive configuration.

  In the above-described embodiment, the engagement protrusion 45 f as the first engagement portion is formed at the center of the fθ lens 45 in the main scanning direction, and the engagement protrusion 45 f is formed on the holder 100. The fθ lens 45 is positioned in the main scanning direction by engaging with the engaging hole 100k as the second engaging portion.

  According to this configuration, the expansion characteristic of the fθ lens 45 can be improved as compared with the case where both ends of the fθ lens 45 in the main scanning direction are brought into contact with the housing 43. That is, the thermal expansion characteristics of the fθ lens 45 are symmetric with respect to the central portion in the main scanning direction. Accordingly, it is possible to suppress the curvature and displacement of the scanning light imaged on the surfaces of the photosensitive drums 10a to 10d by the fθ lens 45. As a result, the image quality of the printed image by the image forming apparatus 1 can be improved.

<< Other embodiments >>
The present invention may be configured as follows with respect to the above embodiment.

That is, in the above embodiment, the leaf spring (an example of a fixing member) 103 is configured to press the fθ lens 45 via the holder 100 (see FIG. 7), but is not limited thereto. For example, as shown in FIG. 9, the leaf spring 103 may be configured to directly press the fθ lens 45.

In the above embodiment, Kakarigo突portion 45f formed on the fθ lens 45, by engaging the engaging hole 100k formed in the holder 100, and positioning in the main scanning direction of the fθ lens 45 is made However, it is not limited to this. That is, the fθ lens 45 may be positioned in the main scanning direction by bringing both end portions of the fθ lens 45 into direct contact with the housing 43.

  In the above embodiment, a tandem color printer has been described as an example of the image forming apparatus 1. However, the present invention is not limited to this. For example, the image forming apparatus 1 may be a monochrome printer. Needless to say, the image forming apparatus 1 is not limited to a printer, but may be a copying machine or a multifunction peripheral.

  As described above, the present invention is useful for an optical scanning device and an image forming apparatus including the optical scanning device, and particularly includes a lens holding member having a correction mechanism that corrects the deflection of the lens in the sub-scanning direction. It is useful for optical scanning devices and image forming apparatuses.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10a Photosensitive drum 10b Photosensitive drum 10c Photosensitive drum 10d Photosensitive drum 10p The peripheral surface (scanned surface) of the photosensitive drum
10q Photosensitive drum peripheral surface (scanned surface)
10r Photosensitive drum peripheral surface (scanned surface)
10s Photosensitive drum peripheral surface (scanned surface)
40 Light Source 43 Housing 44 Polygon Mirror (Deflector)
45 fθ lens (imaging lens)
43 Housing 45a One side surface 45b in the sub-scanning direction One side surface 45c in the optical axis direction A part of one side surface in the sub-scanning direction (first contact portion)
45d Protruding part (second contact part)
45f engagement protrusion (first engagement portion)
100 holder (lens holding member)
100k engagement hole (second engagement part)
100a First vertical wall (vertical wall)
100b Upper flange part
100c Lower flange part
104 Leaf spring (biasing member)
150 Correction mechanism

Claims (3)

A light source unit that emits laser light, a deflector that reflects the laser light emitted from the light source unit and deflects and scans it in the main scanning direction, and forms an image of the laser beam that has been deflected and scanned on the surface to be scanned. An image lens, a housing that houses the deflector and the imaging lens, and a lens holding member that includes a correction mechanism that corrects the imaging lens to bend in the sub-scanning direction when viewed from the optical axis direction; An optical scanning device comprising:
The lens holding member extends in the main scanning direction facing the other side opposite to the one side in the optical axis direction of the imaging lens, and has a vertical wall having an opening through which light passes, and the vertical wall An upper flange portion that protrudes in the optical axis direction from the upper end portion of the portion and faces the upper surface in the sub-scanning direction of the imaging lens, and a lower portion that protrudes from the lower end portion of the vertical wall portion to the opposite side of the imaging lens Side flange part,
The correction mechanism includes an adjustment screw that is screwed into a screw hole formed in a central portion of the upper flange portion in the main scanning direction and a tip portion of which is in contact with the upper side surface of the imaging lens in the sub scanning direction; The side flange portion is fixed to the center portion in the main scanning direction, and the lower surface of the imaging lens in the sub-scanning direction is pressed upward in the sub-scanning direction so that the upper surface of the imaging lens becomes the tip of the adjustment screw A biasing member that presses against the part,
At both ends in the main scanning direction definitive the lower surface of the sub-scanning direction of the imaging lens, a first contact portion abutting directly to the casing is formed,
At both ends in the main scanning direction definitive to the one side face of the optical axis direction of the imaging lens, a second contact portion which abuts directly on the casing is formed,
The imaging lens, by making the first and second abutment portions abut directly on the housing, have been made to position the sub-scanning direction and the optical axis direction with respect to the housing,
An optical scanning device further comprising: a fixing member that fixes the lens holding member to the housing in a state where the imaging lens is positioned . The optical scanning device according to claim 1,
A first engagement portion is formed at the center of the imaging lens in the main scanning direction,
The optical scanning device, wherein the lens holding member is formed with a second engaging portion for positioning the imaging lens in the main scanning direction by engaging with the first engaging portion.   An image forming apparatus comprising the optical scanning device according to claim 1.

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