JP7619914B2 - Optical scanning device and image forming apparatus equipped with the same - Google Patents

Description

The present invention relates to an optical scanning device and an image forming device equipped with the same, such as a copying machine, a multifunction machine, a printer, or a facsimile machine.

Some optical scanning devices have a long fθ lens that focuses a light beam on an object to be irradiated, and can be rotated around a rotation axis that runs along the thickness direction of the fθ lens.

For example, Patent Document 1 describes a configuration that includes an inclined portion (cam member) having an inclined surface that intersects with the rotation axis, and when adjusting the rotation of the fθ lens around the rotation axis, the inclined portion moved by an adjustment member (adjustment screw) directly presses the fθ lens (lens) through point contact, thereby rotating the fθ lens around the rotation axis.

JP 2010-8761 A

However, in the configuration described in Patent Document 1, the inclined portion directly presses the fθ lens through point contact, so stress is concentrated partially on the fθ lens, making it prone to distortion.

The present invention aims to provide an optical scanning device that can effectively prevent distortion of the fθ lens when adjusting the rotation of the fθ lens around the rotation axis, and an image forming device equipped with the same.

In order to solve the above problems, the present invention provides an optical scanning device and an image forming apparatus according to the following first and second aspects.
(1) Optical Scanning Device of First Aspect
According to a first aspect of the present invention, there is provided an optical scanning device capable of adjusting a rotation of a long fθ lens that focuses a light beam on an irradiated object around a rotation axis along a thickness direction of the fθ lens, the optical scanning device comprising: a holding member that is rotatable around the rotation axis and holds the fθ lens; an inclined portion that is integrated with the holding member and has an inclined surface that intersects with the rotation axis; and an adjustment member that directly presses the inclined surface from a direction intersecting the inclined surface of the inclined portion to rotate the holding member together with the fθ lens around the rotation axis , the adjustment member comprising a male screw member having a male screw portion, the male screw member being provided with a rotation locking member that can be locked at a plurality of locking points in a circumferential direction around the rotation axis of the male screw member at predetermined locking rotation angles, the locking rotation angles being uniform within one revolution of the male screw member, and the male screw member being provided with a rotation locking member that can be locked at a plurality of locking points in a circumferential direction around the rotation axis of the male screw member at predetermined locking rotation angles, the locking rotation angles being uniform within one revolution of the male screw member, the male screw member rotates and the tip of the male screw portion abuts the inclined surface of the inclined portion, the male screw member moves in the direction of the rotation axis of the male screw member by the screw pitch of the male screw portion to rotate the holding member together with the fθ lens around the rotation axis by the inclination angle θ of the inclined surface with respect to the longitudinal direction of the fθ lens, the adjustment member rotates and adjusts one side of the holding member in the longitudinal direction about the rotation axis, and each time the rotation locking member rotates to the locking rotation angle, the rotation locking member rotates the adjustment member evenly for each locking rotation angle to rotate the holding member together with the fθ lens around the rotation axis, thereby making it possible to adjust the pixel pitch, which is the pitch in the sub-scanning direction of the pixels of the image formed on the light-irradiated body by the light beam focused by the fθ lens, by one pitch at a time .
(2) Optical Scanning Device of Second Aspect
A second aspect of the optical scanning device according to the present invention is an optical scanning device capable of adjusting the rotation of a long fθ lens that focuses a light beam on an irradiated object around a rotation axis along a thickness direction of the fθ lens, and comprises: a holding member that is rotatable about the rotation axis and holds the fθ lens; an inclined portion that is integrated with the holding member and has an inclined surface that intersects with the rotation axis; and an adjustment member that directly presses the inclined surface from an intersecting direction that intersects with the inclined surface of the inclined portion to rotate the holding member together with the fθ lens around the rotation axis, wherein the adjustment member comprises a male screw member having a male screw portion, and the male screw member is provided with a rotation locking member that can be locked at multiple locking points in the circumferential direction around the rotation axis of the male screw member for each predetermined locking rotation angle, and further comprises a support portion that supports the opposite side to the inclined portion at the tip of the male screw portion .
(3) Image forming device
The image forming apparatus according to the present invention is characterized by including the optical scanning device according to the first or second aspect of the present invention.

According to the present invention, it is possible to effectively prevent distortion of the fθ lens when rotating and adjusting the fθ lens around the rotation axis.

1 is a cross-sectional view showing an image forming apparatus including an optical scanning device according to an embodiment of the present invention. 1 is a plan view illustrating a schematic configuration of an optical scanning device according to an embodiment of the present invention; 2 is a perspective view of the optical scanning device as viewed obliquely from above on the front side with the top cover removed. FIG. 4 is a cross-sectional view of the optical scanning device taken along line AA in FIG. 3. 2 is an enlarged perspective view showing an adjustment portion that rotates and adjusts an fθ lens about a rotation axis in the optical scanning device; FIG. 2 is an enlarged plan view showing an adjustment portion that rotates and adjusts an fθ lens about a rotation axis in the optical scanning device; FIG. FIG. 4 is a plan view showing a state in which the fθ lens is located at a first adjustment position. FIG. 13 is a plan view showing a state in which the fθ lens is located at a second adjustment position. 2 is a perspective view of an adjustment unit in the optical scanning device as viewed from the upper left on the front side. FIG. 2 is a perspective view of an adjustment unit in the optical scanning device as viewed from the upper right on the front side. FIG. FIG. 7C is an enlarged perspective view of the adjustment section shown in FIG. 7B. 4 is a front view showing the adjustment member, the rotation locking member, and the locked portion. FIG. FIG. 4 is an exploded perspective view showing an adjustment member, a rotation locking member, and a locked portion. FIG. 4 is an exploded perspective view showing an adjustment member and a rotation locking member. FIG. 2 is an exploded perspective view showing an fθ lens and a holding member. 11 is a plan view showing the other side portion of the fθ lens in the longitudinal direction. FIG. 11 is a perspective view showing the other side portion of the fθ lens in the longitudinal direction. FIG. FIG. 13 is a perspective view showing a state in which a pressing member on one side in the longitudinal direction of the fθ lens has been removed. FIG. 13B is a perspective view showing a state in which the fθ lens is removed from the state shown in FIG. 13A. 13C is a perspective view showing a state in which the holding member has been removed from the state shown in FIG. 13B. 13 is a perspective view showing a state in which a pressing member on the other side in the longitudinal direction of the fθ lens has been removed. FIG. FIG. 14B is a perspective view showing a state in which the fθ lens is removed from the state shown in FIG. 14A. 14C is a perspective view showing a state in which the holding member has been removed from the state shown in FIG. 14B.

The following describes an embodiment of the present invention with reference to the drawings. In the following description, identical parts are given the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

(Image forming apparatus)
1 is a cross-sectional view showing an image forming apparatus 1 equipped with an optical scanning device 100 according to the present embodiment. In the drawing, the direction perpendicular to the main scanning direction X is defined as the width direction Y (sub-scanning direction), and the direction perpendicular to the main scanning direction X and the width direction Y is defined as the up-down direction Z in the following description.

The image data handled by the image forming device main body 11 of the image forming device 1 corresponds to a color image using each of the colors black (K), cyan (C), magenta (M) and yellow (Y) or a monochrome image using a single color (e.g. black). For this reason, four developing devices 12, photoconductor drums 13, drum cleaning devices 14 and chargers 15 are provided each in units of four toner images for each color, and four image stations Pa, Pb, Pc and Pd are configured, each corresponding to black, cyan, magenta and yellow.

In each image station Pa, Pb, Pc, Pd, the drum cleaning devices 14-14 remove and collect residual toner from the surfaces of the photoconductor drums 13-13, and then the chargers 15-15 uniformly charge the surfaces of the photoconductor drums 13-13 to a predetermined potential. The optical scanning device 100 exposes the surfaces of the photoconductor drums 13-13 to light, forming electrostatic latent images on the surfaces of the photoconductor drums 13-13. The developing device 12 develops the electrostatic latent images on the surfaces of the photoconductor drums 13-13 to form toner images on the surfaces of the photoconductor drums 13-13. As a result, toner images of each color are formed on the surfaces of the photoconductor drums 13-13.

Then, while the intermediate transfer belt 21 is rotated, the belt cleaning device 22 removes and collects the residual toner on the intermediate transfer belt 21, and the toner images of each color on the surface of each photoconductor drum 13-13 are sequentially transferred and superimposed onto the intermediate transfer belt 21 to form a color toner image on the intermediate transfer belt 21.

A nip area is formed between the intermediate transfer belt 21 and the transfer roller 23a of the secondary transfer device 23, and the recording paper transported through the paper transport path 31 is sandwiched in the nip area and transported while the color toner image on the surface of the intermediate transfer belt 21 is transferred onto the recording paper. The recording paper is then sandwiched between the heating roller 24 and pressure roller 25 of the fixing device 17 and heated and pressurized to fix the color toner image on the recording paper.

The recording paper is pulled out of the paper feed cassette 18 by the pickup roller 33, transported through the paper transport path 31, passed through the secondary transfer device 23 and the fixing device 17, and discharged to the paper discharge tray 39 via the paper discharge roller 36. On the paper transport path 31, there are arranged a registration roller 34 that temporarily stops the recording paper, aligns the leading edge of the recording paper, and then starts transporting the recording paper in accordance with the transfer timing of the toner image in the nip area between the intermediate transfer belt 21 and the transfer roller 23a, a transport roller 35 that promotes the transport of the recording paper, etc.

(Optical scanning device)
Next, an example of the optical scanning device 100 according to the present embodiment that is provided in the image forming apparatus 1 will be described below.

Figure 2 is a plan view showing a schematic diagram of the optical scanning device 100 according to the present embodiment. Figure 3 is a perspective view of the optical scanning device 100 with the top cover 121 removed, viewed obliquely from above on the front side. Figure 4 is a cross-sectional view of the optical scanning device 100 taken along line A-A shown in Figure 3.

The optical scanning device 100 includes a rectangular top cover 121 (see FIG. 2) and a housing 120. The housing 120 is made of a resin material and includes a bottom plate 122 and four side walls 123a-123d (see FIG. 3) surrounding the bottom plate 122. The side walls 123a-123d are the front, rear, left and right side walls, respectively. The housing 120 is closed and dustproof by the top cover 121. As shown in FIG. 2, the optical scanning device 100 guides light beams L-L emitted from a plurality of light-emitting elements 151-151 (semiconductor lasers) serving as light sources to the reflecting surface of a deflector 140 (polygon mirror), and the light beams L-L are reflected and deflected by the reflecting surface of the deflector 140.

The reflected light beams L-L are guided by the optical members provided inside the housing 120 to the photosensitive drums 13-13 as the scanned bodies. The optical scanning device 100 is configured to scan the corresponding photosensitive drums 13-13 with the light beams L-L.

From each light-emitting element 151-151 to the deflector 140, four collimator lenses 152-152, four first mirrors 153a, 153b-153b, a cylindrical lens 154, and a second mirror 155 are arranged in the order from each light-emitting element 151-151 to the deflector 140.

The collimator lenses 152-152 convert the light beams L-L emitted from the light-emitting elements 151-151 into parallel light. The three first mirrors 153b-153b reflect the light beams L-L incident from the three light-emitting elements 151-151 through the respective collimator lenses 152-152 to the single first mirror 153a. The single first mirror 153a reflects the light beams L-L reflected by the three first mirrors 153b-153b to the cylindrical lens 154. The light beam L transmitted through the collimator lens 152 from the other single light-emitting element 151 passes above the first mirror 153a and enters the cylindrical lens 154. The cylindrical lens 154 converges the light beam L only in the sub-scanning direction and focuses it on the reflecting surface of the deflector 140 via the second mirror 155.

Deflector 140 deflects and scans light beams L-L emitted from light-emitting elements 151-151 onto photosensitive drums 13-13 (an example of a light-irradiated body). In more detail, deflector 140 rotates at high speed around rotation axis G, and reflects light beams L-L on each reflective surface to repeatedly deflect them in the main scanning direction X.

As shown in FIG. 4, in the optical scanning device 100, multiple reflecting mirrors 161-168 are provided in the housing 120 so as to guide the light beams L-L deflected by the deflector 140 to each of the photosensitive drums 13-13. In more detail, in the optical path from the deflector 140 to each of the photosensitive drums 13-13, a common fθ lens 170, multiple reflecting mirrors 161-168, and multiple (four in this example) fθ lenses 110-110 are arranged in the order from the deflector 140 to each of the photosensitive drums 13-13.

The multiple reflecting mirrors 161-168 reflect the incident light beams L-L toward the respective photoconductor drums 13-13. As shown in FIG. 2, the top cover 121 is formed with four dustproof windows 121a-121a that allow the reflected light beams L-L to pass through. The dustproof windows 121a-121a are configured to close the opening of the top cover 121 with, for example, transparent glass. The light beams L-L that pass through the dustproof windows 121a-121a are imaged on the photoconductor drums 13-13.

The fθ lens 170 is made of a resin material and extends in the main scanning direction X. The fθ lens 170 focuses and emits the light beams L-L to a predetermined beam diameter on the surface of each of the photoconductor drums 13-13. The fθ lens 170 also converts the light beams L-L deflected at a constant angular velocity in the main scanning direction X by the deflector 140 so that they move at a constant linear velocity along the main scanning line on each of the photoconductor drums 13-13. As a result, the light beams L-L repeatedly scan the surfaces of each of the photoconductor drums 13-13 in the main scanning direction X.

The multiple reflecting mirrors 161-168 provided in the optical path reflect the light beams L-L that have passed through the fθ lens 170, causing them to enter the multiple fθ lenses 110-110, respectively. The multiple fθ lenses 110-110 are made of a resin material and extend in the main scanning direction X. The multiple fθ lenses 110-110 mainly focus the parallel light beams L-L in the sub-scanning direction to a predetermined beam diameter (spot diameter) on the surface of each of the photoconductor drums 13-13, and also emit the convergent light beams L-L to each of the photoconductor drums 13-13 in the main scanning direction X.

In the optical scanning device 100 described above, each light beam L-L is reflected and deflected by the reflecting surface of the deflector 140, passes through its respective optical path, and is incident on each photoconductor drum 13-13, repeatedly main-scanning the surface of each photoconductor drum 13-13. As each photoconductor drum 13-13 is driven to rotate, each light beam L-L scans the surface (circumferential surface) of each photoconductor drum 13-13, and an electrostatic latent image is formed on the surface of each photoconductor drum 13-13.

(About this embodiment)
The optical scanning device 100 according to this embodiment is configured such that the long fθ lenses 110, which focus the light beams L on the photosensitive drums 13, can be rotated and adjusted around a rotation axis α along the thickness direction (vertical direction Z) of the fθ lenses 110. The optical scanning device 100 includes light emitting elements 151, the fθ lenses 110, and a plurality of (four in this example) adjustment units 180 (see FIG. 3).

The fθ lenses 110-110 are disposed on the optical path between the deflector 140 and the photoconductor drums 13-13. The adjustment units 180-180 are configured to rotate and adjust the fθ lenses 110-110 around the rotation axis α.

5A and 5B are respectively an enlarged perspective view and a plan view of the adjustment unit 180 that rotates and adjusts the fθ lens 110 around the rotation axis α in the optical scanning device 100. FIGS. 6A and 6B are plan views showing the fθ lens 110 in the first and second adjustment positions. Since the multiple adjustment units 180-180 all have the same configuration, the following description will be given using only one adjustment unit 180 as a representative. The reference adjustment position shown in FIGS. 5A and 5B is a position where the longitudinal axis γ of the fθ lens 110 is along the reference virtual straight line β, and the first adjustment position shown in FIG. 6A and the second adjustment position shown in FIG. 6B are positions where the longitudinal axis γ of the fθ lens 110 is rotated around the rotation axis α with respect to the reference virtual straight line β.

The adjustment unit 180 rotates and adjusts around a rotation axis α (see FIG. 3) that runs along the thickness direction (vertical direction Z, height direction) of the fθ lens 110.

The fθ lens 110 is rotatable in a rotation direction C around a rotation axis α. The rotation angle φ of the fθ lens 110 (see FIGS. 6A and 6B) is the angle of the longitudinal axis γ along the longitudinal direction N of the fθ lens 110 with respect to a reference imaginary straight line β. Here, the reference imaginary straight line β is an imaginary straight line along the main scanning direction X in which the light beam L is scanned by the deflector 140. The rotation angle φ is not limited to this, but can be approximately 30 degrees to 50 degrees. In this example, the rotation angle φ is approximately 40 degrees.

Figures 7A and 7B are perspective views of the adjustment unit 180 in the optical scanning device 100, respectively, viewed from the upper left and upper right of the front side. Figure 8 is an enlarged perspective view of the adjustment unit 180 portion shown in Figure 7B. Figures 9A and 9B are a front view and an exploded perspective view, respectively, showing the adjustment member 183, the rotation locking member 184, and the locked portion 185. Figure 10 is an exploded perspective view showing the adjustment member 183 and the rotation locking member 184.

The optical scanning device 100 according to this embodiment includes a holding member 181, an inclined portion 182, and an adjustment member 183. The holding member 181 is rotatable around a rotation axis α. The holding member 181 holds the fθ lens 110. The inclined portion 182 is integrated with the holding member 181 and has an inclined surface 182a that intersects with the rotation axis α. The adjustment member 183 directly presses the inclined surface 182a from a cross direction (main scanning direction X in this example) that intersects with the inclined surface 182a of the inclined portion 182, thereby rotating the holding member 181 together with the fθ lens 110 around the rotation axis α.

In this way, the fθ lens 110 is held by the holding member 181, and presses against the inclined surface 182a of the inclined portion 182 integrated with the holding member 181, and does not press directly against the fθ lens 110, so that it is possible to avoid partial concentration of stress on the fθ lens 110, and this makes it difficult for the fθ lens 110 to become distorted. Therefore, when the fθ lens 110 is rotated and adjusted around the rotation axis α, it is possible to effectively prevent distortion of the fθ lens 110.

First Embodiment
In this embodiment, the adjustment member 183 is equipped with a male screw member 183a. The male screw member 183a has a male screw portion 183a1. The male screw member 183a is provided with a rotation locking member 184. The rotation locking member 184 can be locked at a plurality of locking points in the circumferential direction around the rotation axis δ (see FIG. 9) of the male screw member 183a at predetermined locking rotation angles λ (see FIG. 9).

In this way, the adjustment member 183 can be moved precisely by the locking rotation angle λ and the screw pitch of the male screw portion 183a1, and the fθ lens 110 can be rotated and adjusted precisely around the rotation axis α.

Second Embodiment
However, if the locking rotation angle λ differs for each locking angle of the adjustment member 183 by the rotation locking member 184, the fθ lens 110 cannot be rotated and adjusted accurately about the rotation axis α.

In this respect, in this embodiment, the locking rotation angle λ is an even angle within one revolution of the male screw member 183a. When the male screw member 183a rotates, the tip 183b of the male screw portion 183a1 abuts against the inclined surface 182a of the inclined portion 182, and the male screw member 183a moves in the direction of the rotation axis of the male screw member 183a (in this example, the longitudinal direction N of the fθ lens 110) by the screw pitch of the male screw portion 183a1, rotating the holding member 181 together with the fθ lens 110 around the rotation axis α by the inclination angle θ of the inclined surface 182a relative to the longitudinal direction N.

In this way, each time the rotating locking member 184 rotates to the locking rotation angle λ, the rotating locking member 184 can uniformly adjust the adjustment member 183 for each locking rotation angle λ. This allows the fθ lens 110 to be rotated and adjusted with high precision around the rotation axis α. Here, the locking rotation angle λ can be determined by the thread pitch of the male screw portion 183a1 and the inclination angle θ of the inclined surface 182a relative to the longitudinal direction N of the fθ lens 110.

If the number of times that the rotating locking member 184 locks the adjustment member 183 in one revolution is too large, the rotating locking member 184 will not be able to securely lock the adjustment member 183.

Therefore, it is preferable that the number of times the rotation locking member 184 locks the adjustment member 183 in one revolution is an integer equal to or less than 15, obtained by dividing 360 degrees by the locking rotation angle λ.

Third Embodiment
In this embodiment, each time the rotary locking member 184 rotates through the locking rotation angle λ, the pixel pitch, which is the pitch in the sub-scanning direction of the pixels of the image formed on the photoconductor drum 13, can be adjusted by one pitch. For example, if the resolution of the image formed on the photoconductor drum 13 is 600 dpi, 1200 dpi, or 2400 dpi, the pixel pitch is 42.33 μm, 21.17 μm, or 10.58 μm, respectively.

In this way, the pixel pitch can be adjusted by one pitch at a time by rotating the adjustment member 183 by the locking rotation angle λ using the rotating locking member 184.

Fourth Embodiment
In this embodiment, a locked portion 185 is provided on the side wall 123a of the housing 120. Also, a female screw member 186 is provided on the housing 120 (see first rib 125 in Figs. 5A and 5B). The rotation locking member 184 is provided with a locking portion 184a. The locked portion 185 is provided with a plurality of uneven portions 185a to 185a (see Figs. 5, 9A, and 9B) that lock the locking portion 184a of the rotation locking member 184. The female screw member 186 screws into the male screw portion 183a1 of the male screw member 183a.

This allows the adjustment member 183 to be securely locked by the uneven portions 185a-185a and the locking portion 184a. This allows the fθ lens 110 to be reliably rotated and adjusted around the rotation axis α.

In this embodiment, the rotating locking member 184 is provided with three or more locking portions 184a-184a (three in this example).

This allows the adjustment member 183 to be stably locked by the uneven portions 185a-185a and the locking portions 184a-184a. This allows the fθ lens 110 to be reliably rotated and adjusted around the rotation axis α.

Fifth Embodiment
Incidentally, when the tip 183b of the male screw portion 183a1 is pressed against the inclined surface 182a of the inclined portion 182, a reaction force from the inclined surface 182a is applied to the tip 183b of the male screw portion 183a1 in a direction perpendicular to the inclined surface 182a. This may cause the tip 183b of the male screw portion 183a1 to bend.

In this regard, in this embodiment, the optical scanning device 100 further includes a support portion 187. The support portion 187 supports the side of the tip portion 183b of the male screw portion 183a1 opposite the inclined portion 182. In more detail, the support portion 187 is in contact with or close enough to not contact the side of the tip portion 183b of the male screw portion 183a1 opposite the inclined portion 182.

By doing this, even if the tip 183b of the male screw portion 183a1 is pressed against the inclined surface 182a of the inclined portion 182 and a reaction force is applied to the tip 183b of the male screw portion 183a1 from the inclined surface 182a, the tip 183b of the male screw portion 183a1 can be effectively prevented from bending.

Sixth Embodiment
Here, when the support portion 187 supports the side opposite the inclined portion 182 at the tip portion 183b of the male screw portion 183a1, if a male screw 183m (see Figures 6A, 6B, and 10) is provided in at least the portion of the male screw portion 183a1 that is supported by the support portion 187, the support portion 187 will slide against the male screw 183m, making it easy for the support portion 187 to be worn down.

In this embodiment, at least the portion of the male screw portion 183a1 that is supported by the support portion 187 has a cylindrical non-male screw portion 183a2 (see Figures 9B and 10) that does not have a male screw 183m.

This allows the support portion 187 to slide against the non-male thread portion 183a2, making the support portion 187 less likely to be worn down.

Seventh Embodiment
In this embodiment, the inclined surface 182 a is inclined in a direction away from the fθ lens 110 as the pressure of the adjustment member 183 against the inclined portion 182 increases.

By doing this, when the tip 183b of the male screw member 183a is pressed against the inclined surface 182a of the inclined portion 182, the fθ lens 110 can be smoothly rotated and adjusted around the rotation axis α.

In this embodiment, the inclined portion 182 has an extension portion 182b and a standing portion 182c. The extension portion 182b extends from the holding member 181 toward the adjustment member 183. The standing portion 182c stands upright from the extension portion 182b. An inclined surface 182a is provided on the adjustment member 183 side of the standing portion 182c.

By doing this, the inclined surface 182a can be reliably formed with a simple configuration in which the extension portion 182b is erected from the extension portion 182b that is extended from the holding member 181 toward the adjustment member 183.

Eighth Embodiment
In this embodiment, a biasing member 188 that biases the holding member 181 toward the adjustment member 183 is provided on the opposite side of the holding member 181 to the adjustment member 183 .

By doing so, when the holding member 181 is rotated and adjusted together with the fθ lens 110 around the rotation axis α, the adjustment member 183 moves in a direction pressing the inclined surface 182a, and the holding member 181 can be reliably rotated around the rotation axis α against the biasing force of the biasing member 188. Also, the adjustment member 183 moves in a direction retracting from the inclined surface 182a, and the biasing force of the biasing member 188 can reliably rotate the holding member 181 around the rotation axis α.

[Specific configuration]
FIG. 11 is an exploded perspective view showing the fθ lens 110 and the holding member 181. FIG. 12A and FIG. 12B are a plan view and a perspective view showing the other side portion of the fθ lens 110 in the longitudinal direction N, respectively. FIG. 13A is a perspective view showing a state in which the pressing member 1811 on one side of the fθ lens 110 in the longitudinal direction N has been removed. FIG. 13B is a perspective view showing a state in which the fθ lens 110 has been removed from the state shown in FIG. 13A. FIG. 13C is a perspective view showing a state in which the holding member 181 has been removed from the state shown in FIG. 13B. FIG. 14A is a perspective view showing a state in which the pressing member 1811 on the other side of the fθ lens 110 in the longitudinal direction N has been removed. FIG. 14B is a perspective view showing a state in which the fθ lens 110 has been removed from the state shown in FIG. 14A. FIG. 14C is a perspective view showing a state in which the holding member 181 has been removed from the state shown in FIG. 14B.

(Adjustment section)
The adjustment unit 180 is provided at an end on one side in the longitudinal direction N of the fθ lens 110 (in this example, the front side, the operation side).

(Holding member)
The holding member 181 is a plate-shaped sheet metal member and has a bottom plate 181a and side plates 181b and 181c. The side plates 181b and 181c are formed by bending the bottom plate 181a so as to stand from both ends in a width direction Y perpendicular to the longitudinal direction N. The fθ lens 110 is disposed on a holding surface 181a1 which is the upper surface of the bottom plate 181a. An opening 181a2 along the longitudinal direction N is provided in a portion of the bottom plate 181a through which the light beam L of the fθ lens 110 passes. An inclined portion 182 is integrally formed on one side (front side) in the longitudinal direction N of the bottom plate 181a.

A pair of restricting portions 181d, 181d (see FIG. 13B) that restrict movement of the fθ lens 110 in the width direction Y are provided on one side of the holding member 181 in the longitudinal direction N. The pair of restricting portions 181d, 181d hold both sides of the fθ lens 110 in the width direction Y on one side of the longitudinal direction N.

A pair of restricting portions 181e, 181e (see FIG. 14B) that restrict movement of the fθ lens 110 in the width direction Y are provided on the other side (rear side) in the longitudinal direction N of the holding member 181. The pair of restricting portions 181e, 181e hold both sides of the fθ lens 110 in the width direction Y on the other side in the longitudinal direction N.

The other side of the holding member 181 in the longitudinal direction N is provided with a through hole 181f (see FIG. 14B) that restricts movement of the fθ lens 110 in the width direction Y and the longitudinal direction N. The opposing surface 110a (see FIG. 11) of the fθ lens 110 facing the holding member 181 is provided with a protrusion 110b (see FIG. 11) that protrudes toward the holding member 181. The protrusion 110b of the fθ lens 110 is inserted into the through hole 181f of the holding member 181.

The corners of the opposing surface 110a of the fθ lens 110 are provided with protrusions 110c-110c (see FIG. 11). The holding surface 181a1 of the holding member 181 is provided with protrusions 181g-181g (see FIG. 13B and FIG. 14B) at portions corresponding to the protrusions 110c-110c.

The fθ lens 110 is placed on the holding surface 181a1 of the holding member 181 with the protrusions 110c-110c in contact with the protrusions 181g-181g.

In addition, a circular recess 124 (Fig. 14C) is provided on the other side in the longitudinal direction N of the housing 120 to rotate and adjust the fθ lens 110 around the rotation axis α. A protrusion 181h (see Fig. 11) that protrudes toward the housing 120 is provided on the surface 181a3 (see Fig. 11) of the holding member 181 facing the housing 120. The protrusion 181h of the holding member 181 is inserted into the recess 124 of the housing 120. This allows the holding member 181 to rotate around the rotation axis α with the protrusion 181h as the fulcrum.

The corners of the surface 181a3 (see FIG. 11) of the holding member 181 facing the housing 120 are provided with protrusions 181i-181i (see FIG. 11). The bottom surface 120a of the housing 120 is provided with protrusions 120b-120b (see FIG. 13C and FIG. 14C) in portions that correspond to the protrusions 181i-181i.

The holding member 181 is placed on the bottom surface 120a of the housing 120 with the protrusions 181i-181i in contact with the protrusions 120b-120b.

(Inclined portion)
In the inclined portion 182, the extension portion 182b is integrally provided extending from the bottom plate 181a toward the adjustment member 183. The standing portion 182c is formed by bending so as to stand from the end of the extension portion 182b on the adjustment member 183 side.

(Adjustment member)
As shown in FIG. 10, in the adjustment member 183, the male screw member 183a is composed of a head 1841 and a shaft portion 1842. The male screw member 183a is formed of a metal material. The head 1841 has an engagement portion 1841a that engages with a jig such as a screwdriver. The shaft portion 1842 is composed of a fixing portion 183a3, a male screw portion 183a1, and a non-male screw portion 183a2. The fixing portion 183a3 fixes the rotation locking member 184. More specifically, the rotation locking member 184 is provided with a circular through hole 184d along the longitudinal direction N. The rotation locking member 184 is formed of a resin material. The outer diameter of the fixing portion 183a3 is slightly larger (by a predetermined distance) than the inner diameter of the through hole 184d. This allows the fixing portion 183a3 to be press-fitted into the through hole 184d of the rotation locking member 184. In this example, the surface of the fixed portion 183a3 is knurled.

As shown in Figures 6A and 6B, the female screw member 186 has a female screw portion 186a. This allows the fθ lens 110 to be rotated and adjusted precisely around the rotation axis α.

The female screw member 186 is a plate-shaped member. The female screw member 186 is provided with a female screw 186f that corresponds to the male screw 183m of the male screw portion 183a1 of the male screw member 183a. The housing 120 is provided with a first rib 125 (see Figures 5A, 5B, 13A to 13C) that holds the female screw member 186. The first rib 125 is recessed toward the thickness direction (vertical direction Z) of the fθ lens 110. This allows the female screw member 186 to be inserted and held in the first rib 125. In this example, the thickness of the female screw member 186 is about 1.5 mm, and the screw pitch of the male screw portion 183a1 and the female screw portion 186a is about 0.5 mm. The side wall 123a also has a female screw 186f that corresponds to the male screw 183m of the male screw portion 183a1 of the male screw member 183a. This allows the fθ lens 110 to be rotated and adjusted around the rotation axis α with even greater precision.

(Rotational locking member)
As shown in Fig. 10, the rotation locking member 184 has a cylindrical member 184b with a through hole 184d and arm portions 184c to 184c. The center of the cylindrical member 184b coincides with the rotation axis δ of the male screw member 183a. On the outer circumferential surface of the cylindrical member 184b, locking portions 184a to 184a are provided evenly in the circumferential direction via arm portions 184c to 184c. The arm portions 184c to 184c have elasticity and are curved in the circumferential direction. The locking portions 184a to 184a, the cylindrical member 184b, and the arm portions 184c to 184c are integrally formed of resin.

(Engaged portion)
9A and 9B, the locked portion 185 is a through hole into which the rotation locking member 184 is inserted in the side wall 123a on the front side of the housing 120. The inner peripheral surface of the locked portion 185 is provided with uneven portions 185a. In this example, the uneven portions 185a are formed in a triangular shape in a cross-sectional view.

(Support part)
5A and 5B , the support portion 187 is a semi-cylindrical rib extending in the thickness direction (vertical direction Z) of the fθ lens 110. The support portion 187 is provided integrally with the second rib 126 erected from the bottom surface 120a of the housing 120. The second rib 126 is formed integrally with the first rib 125.

(Using member)
The biasing member 188 biases one end of the holding member 181 in the longitudinal direction N toward the adjustment member 183. In this example, the biasing member 188 is a compression spring. The biasing member 188 is provided between the fθ lens 110 and a third rib 127 provided on the housing 120 so as to press the holding member 181 toward the adjustment member 183. At one end of the holding member 181 in the longitudinal direction N, on the opposite side to the adjustment member 183, an engagement portion 111 for engaging the biasing member 188 is provided. The engagement portion 111 protrudes from the side plate 181c on the opposite side to the adjustment member 183.

(Pressing member)
The optical scanning device 100 further includes a pressing member 1811. The pressing member 1811 presses the fθ lens 110 placed on the holding member 181 toward the holding member 181. At this time, the pressing member 1811 presses the fθ lens 110 placed on the holding member 181 with a pressure sufficient to rotate the holding member 181 together with the fθ lens 110 around the rotation axis α.

In this example, the pressing member 1811 is a plate-shaped pressing spring (leaf spring) and is provided at one end and the other end in the longitudinal direction N of the fθ lens 110. The pressing member 1811 is provided with a plurality (two) recesses 1811a, 1811a extending in the longitudinal direction N. This allows the pressing member 1811 to press the upper surface of the fθ lens 110 by line contact on the back side of the recesses 1811a, 1811a, and therefore makes it easier to slide the fθ lens 110 against the pressing member 1811 when the fθ lens 110 rotates around the rotation axis α.

At one end and the other end in the longitudinal direction N of the housing 120, fastening holes 120c, 120c (FIGS. 13A to 13C, 14A to 14C) (screw holes) are provided. The pressing members 1811, 1811 are provided with through holes 1811b (see FIG. 8). The fastening members SC, SC (screws) are fastened to the fastening holes 120c, 120c of the housing 120 while being inserted through the through holes 1811b, 1811b of the pressing members 1811, 1811.

A plurality of (two) positioning protrusions 120d, 120d (FIGS. 12A to 14B) are provided at one end and the other end in the longitudinal direction N of the housing 120. The pressing members 1811, 1811 are provided with a positioning hole 1811c and a positioning notch 1811d (FIGS. 8, 12A, 12B). The pressing members 1811, 1811 are fixed to the housing 120 with the positioning protrusions 120d, 120d of the housing 120 inserted into the positioning hole 1811c and the positioning notch 1811d.

The present invention is not limited to the embodiment described above, and can be embodied in various other forms. Therefore, the embodiment is merely illustrative in all respects and should not be interpreted in a restrictive manner. The scope of the present invention is indicated by the claims, and is not bound by the text of the specification. Furthermore, all modifications and changes within the equivalent scope of the claims are within the scope of the present invention.

1 Image forming apparatus 100 Optical scanning device 110 fθ lens 111 Engagement portion 120 Housing 123a Side wall 13 Photosensitive drum (light-irradiated body)
180 Adjustment portion 181 Holding member 1811 Pressing member 182 Inclined portion 182a Inclined surface 182b Extension portion 182c Standing portion 183 Adjustment member 183a Male screw member 183a1 Male screw portion 183a2 Non-male screw portion 183b Tip portion 184 Rotational locking member 184a Locking portion 185 Locked portion 185a Irregular portion 186 Female screw member 187 Support portion 188 Pressing member L Light beam N Longitudinal direction X Main scanning direction Y Width direction Z Up-down direction α Rotation axis β Reference virtual straight line γ Longitudinal axis δ Rotation axis θ Incline angle λ Locking rotation angle φ Rotation angle

Claims (11)

An optical scanning device capable of adjusting a rotation of a long fθ lens that focuses a light beam on an object to be irradiated, about a rotation axis along a thickness direction of the fθ lens,
a holding member that is rotatable about the rotation axis and holds the fθ lens;
an inclined portion that is integrated with the holding member and has an inclined surface that intersects with the rotation axis;
an adjustment member that directly presses the inclined surface of the inclined portion from a direction intersecting the inclined surface to rotate the holding member together with the fθ lens about the rotation axis;
Equipped with
The adjustment member includes a male screw member having a male screw portion,
the male screw member is provided with a rotation locking member that can be locked at a plurality of locking points in a circumferential direction about a rotation axis of the male screw member at each predetermined locking rotation angle,
the locking rotation angle is a uniform angle within one revolution of the male screw member, the male screw member rotates and the tip end of the male screw portion abuts against the inclined surface of the inclined portion, the male screw member moves in the direction of the rotation axis of the male screw member by the screw pitch of the male screw portion, and the holding member is rotated around the rotation axis together with the fθ lens by the inclination angle θ of the inclined surface with respect to the longitudinal direction of the fθ lens,
the adjustment member rotates and adjusts one side of the holding member in the longitudinal direction about the rotation axis,
an optical scanning device characterized in that a pixel pitch, which is the pitch in the sub-scanning direction of the pixels of an image formed on the light-irradiated body by the light beam focused by the fθ lens, can be adjusted by one pitch at a time by using the rotating locking member to rotate the adjustment member evenly by the locking rotation angle each time the rotating locking member rotates to the locking rotation angle, thereby rotating the holding member together with the fθ lens around the rotation axis . An optical scanning device capable of adjusting a rotation of a long fθ lens that focuses a light beam on an object to be irradiated, about a rotation axis along a thickness direction of the fθ lens,
a holding member that is rotatable about the rotation axis and holds the fθ lens;
an inclined portion that is integrated with the holding member and has an inclined surface that intersects with the rotation axis;
an adjustment member that directly presses the inclined surface of the inclined portion from a direction intersecting the inclined surface to rotate the holding member together with the fθ lens about the rotation axis;
Equipped with
The adjustment member includes a male screw member having a male screw portion,
the male screw member is provided with a rotation locking member that can be locked at a plurality of locking points in a circumferential direction about a rotation axis of the male screw member at each predetermined locking rotation angle ,
The optical scanning device further comprises a support portion for supporting a tip end portion of the male screw portion on a side opposite to the inclined portion. 3. The optical scanning device according to claim 2 ,
2. An optical scanning device according to claim 1, wherein at least a portion of the male screw portion supported by the support portion has a cylindrical non-male screw portion having no male screw. 4. The optical scanning device according to claim 2 ,
an engaging rotation angle that is uniform within one revolution of the male screw member, the male screw member rotates so that the tip of the male screw portion abuts the inclined surface of the inclined portion, and the male screw member moves in the direction of the rotation axis of the male screw member by the screw pitch of the male screw portion, thereby rotating the holding member together with the fθ lens around the rotation axis by the inclination angle θ of the inclined surface relative to the longitudinal direction of the fθ lens . 5. The optical scanning device according to claim 4 ,
the adjustment member rotates and adjusts one side of the holding member in the longitudinal direction about the rotation axis,
an optical scanning device characterized in that a pixel pitch, which is the pitch in the sub-scanning direction of the pixels of an image formed on the light-irradiated body by the light beam focused by the fθ lens, can be adjusted by one pitch at a time by using the rotating locking member to rotate the adjustment member evenly by the locking rotation angle each time the rotating locking member rotates to the locking rotation angle, thereby rotating the holding member together with the fθ lens around the rotation axis. 6. An optical scanning device according to claim 1 ,
Equipped with a housing,
The housing is provided with a locked portion and a female screw member,
The rotation locking member is provided with a locking portion, and the locked portion is provided with a plurality of projections and recesses that lock the locking portion of the rotation locking member,
The optical scanning device according to claim 1, wherein the female screw member is screwed into the male screw portion of the male screw member. 7. The optical scanning device according to claim 6 ,
The optical scanning device according to claim 1, wherein the rotation locking member is provided with three or more of the locking portions. An optical scanning device according to any one of claims 1 to 7 ,
The optical scanning device according to claim 1, wherein the inclined surface is inclined in a direction away from the fθ lens in a pressing direction of the adjustment member toward the inclined portion. An optical scanning device according to any one of claims 1 to 8 ,
The inclined portion has an extension portion that extends from the holding member toward the adjustment member and a standing portion that stands upright from the extension portion,
an optical scanning device, characterized in that the inclined surface is provided on the side of the adjustment member of the erected portion; An optical scanning device according to any one of claims 1 to 9 ,
an adjusting member that adjusts the position of the holding member toward the adjusting member; a biasing member that biases the holding member toward the adjusting member; 11. An image forming apparatus comprising the optical scanning device according to claim 1.

Images