JP4645700B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that exposes a photoreceptor with an exposure unit having a plurality of blinking portions.

  In general, an exposure unit used in an image forming apparatus such as a printer has a plurality of arranged blinking portions (LEDs, etc.) and exposes the photosensitive member at a position close to the photosensitive member (LED head, etc.). (For example, refer to Patent Document 1).

  Such an exposure unit is pressed toward the photosensitive member by a pressing member such as a coil spring in the optical axis direction of the light emitted from the blinking portion. Further, the exposure unit is positioned by contacting at least two or planar positioning members in the moving direction of the photoconductor in order to suppress the swing in the moving direction of the portion of the photoconductor facing the exposure unit. .

JP 2008-18700 A (see FIGS. 2 and 3)

  By the way, in the image forming apparatus, for example, minute vibrations are generated due to an impact or the like when the thick paper comes into contact with the photosensitive drum (photosensitive member) during image formation. This vibration may act as a force that separates the exposure unit from the positioning member by shifting the action point at which the pressing member presses the exposure unit toward the photosensitive member in the moving direction of the photosensitive member. If the action point of the pressing member is shifted in the moving direction of the photosensitive member and the exposure unit is separated from the positioning member, the position of the exposure unit with respect to the photosensitive member is changed, which causes a reduction in image quality.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of suppressing deterioration in image quality by suppressing the influence of vibration on an exposure unit.

In order to achieve the above object, an image forming apparatus according to the present invention includes a photoconductor on which an electrostatic latent image is formed, an exposure unit having a plurality of blinking portions and exposing the photoconductor, and the exposure unit. A first pressing member that presses toward the photoconductor, and a first positioning member that determines a position of the exposure unit in a moving direction of a portion of the photoconductor facing the exposure unit by contacting the exposure unit. And arranged closer to the photoconductor than the first positioning member in the optical axis direction of the light emitted from the exposure unit, and in contact with the exposure unit, the movement direction of the exposure unit a second positioning member for positioning the second pressing member for pressing the side of the exposure unit and the second positioning member is disposed in the moving direction, the dew By contacting the unit, the distance between the exposure unit and the photoconductor is kept constant by coming into contact with the surface of the photoconductor and the third positioning member that determines the position of the exposure unit in the moving direction. An interval holding member, and the first positioning member and the second positioning member are arranged at one end side in the longitudinal direction of the exposure unit, and one of the first positioning member and the second positioning member is arranged upstream of the moving direction with respect to the exposure unit, The other is disposed on the downstream side in the movement direction, the third positioning member is the other end side in the longitudinal direction of the exposure unit, and the second positioning on the upstream side and the downstream side in the movement direction. are located on the same side as members, the working point of the first pressing member for pressing the exposure unit is close to the photosensitive member than the first positioning member in the optical axis direction And it is located on the side.

  According to the image forming apparatus configured as described above, the action point at which the first pressing member presses the exposure unit is located closer to the photoconductor than the first positioning member in the optical axis direction. Thus, even if the action point is shifted in any of the moving directions of the photosensitive member, the action (the influence of vibration) of the exposure unit separating from the positioning member can be suppressed.

  Specifically, when the action point is shifted and a force that separates the exposure unit from the positioning member is applied, for example, the exposure unit is supported by the first positioning member and / or the second positioning member, so The position relative to the body can be stabilized. In addition, the position of the exposure unit relative to the photosensitive member can be stabilized by restricting the exposure unit from being separated from the positioning member by the pressing force of the second pressing member. Further, since the distance between the swing center (fulcrum) and the action point when a force that separates the exposure unit from the positioning member is applied, a relatively large force is required to swing the exposure unit. The position of the exposure unit relative to the photosensitive member can be stabilized against a small force caused by a large vibration.

The image forming apparatus of the present invention includes a photosensitive member on which an electrostatic latent image is formed, an exposure unit having a plurality of blinking portions to expose the photosensitive member, and the exposure unit facing the photosensitive member. A first pressing member to be pressed and a portion having a predetermined length in the optical axis direction of light emitted from the exposure unit, and in contact with the exposure unit, the portion of the photoreceptor facing the exposure unit In the moving direction, a fourth positioning member that determines the position of the exposure unit and a position that faces the fourth positioning member with the exposure unit interposed therebetween, and presses the exposure unit toward the fourth positioning member. a second pressing member, wherein by contact with the surface of the photosensitive member, and a spacing member for holding the distance between the exposure unit and the photosensitive member at a constant, wherein the first pressing member and the exposure Uni Acting point of pressing the door is being located in the outer frame portion of said the movement as viewed from the direction the exposure unit fourth positioning member and is within a region in surface contact, or contacts the surface area And

According to the image forming apparatus configured as described above, an action point at which the first pressing member presses the exposure unit is in a region where the exposure unit and the fourth positioning member are in surface contact as viewed from the moving direction of the photosensitive member , Or, because it is located in the outer frame part of the surface contact area, the action of moving the exposure unit away from the positioning member (effect of vibration) is suppressed even if the action point is shifted in any of the moving direction of the photosensitive member due to vibration. can do.

  Specifically, when the action point is shifted and a force that separates the exposure unit from the positioning member is applied, one of the exposure units is supported by the fourth positioning member, so that the position of the exposure unit relative to the photosensitive member can be stabilized. it can. On the other hand, since the exposure unit is restricted from moving away from the positioning member by the pressing force of the second pressing member, the position of the exposure unit relative to the photoconductor can be stabilized.

  According to the image forming apparatus of the present invention, the influence of vibration on the exposure unit can be suppressed and the position of the exposure unit with respect to the photoconductor can be stabilized. As a result, deterioration in image quality can be suppressed.

[First Embodiment]
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing the overall configuration of a color printer as an example of an image forming apparatus.

  In the following description, the direction will be described with reference to the user who uses the color printer. That is, in FIG. 1, the right side toward the paper surface is the “front” side, the left side toward the paper surface is the “rear” side, the front side toward the paper surface is the “left” side, and the rear side toward the paper surface is “right”. ”Side. In addition, the vertical direction toward the page is the “vertical” direction.

  As shown in FIG. 1, the color printer 1 includes a paper feeding unit 20 that supplies a sheet P (recording sheet) and an image forming unit 30 that forms an image on the fed paper P. And a paper discharge unit 90 for discharging the paper P on which the image is formed.

  A top cover 12 configured to be rotatable up and down (openable and closable) about a rotation shaft 12A provided on the rear side is provided on the upper portion of the main body housing 10. The top cover 12 has an upper surface serving as a paper discharge tray 13 for accumulating the paper P discharged from the main body housing 10, and a plurality of LED mounting portions 14 for supporting the LED unit 40 (exposure unit) on the lower surface. Is provided.

  In addition, a main body frame 15 is provided in the main body housing 10 to detachably accommodate process cartridges 50 described later. The main body frame 15 includes a pair of metal side frames 15A (only one side is shown) opposed in the left-right direction and a cross member 15B provided before and after connecting the pair of side frames 15A. The main body frame 15 is fixed to the main body housing 10 or the like.

  The paper feeding unit 20 is provided in the lower part of the main body housing 10, and is a paper feeding tray 21 that is detachably attached to the main body housing 10, and paper that supplies paper P from the paper feeding tray 21 to the image forming unit 30. A supply mechanism 22 is mainly provided. The paper supply mechanism 22 is provided on the front side of the paper feed tray 21 and mainly includes a paper feed roller 23, a separation roller 24, a separation pad 25, and the like.

  In the paper feeding unit 20 configured as described above, the paper P in the paper feeding tray 21 is separated one by one by the paper feeding mechanism 22 and sent upward, and is passed between the paper dust removing roller 26 and the pinch roller 27. After the paper dust is removed in the process of passing, the direction is changed backward through the conveyance path 28 and supplied to the image forming unit 30.

  The image forming unit 30 mainly includes an LED unit 40 as an example of four exposure units, four process cartridges 50, a transfer unit 70, and a fixing unit 80.

  The LED unit 40 is disposed so as to be opposed to the upper side of the cylindrical photosensitive drum 53 (photosensitive body), and is configured to expose the surface of the photosensitive drum 53. Each LED unit 40 is supported by the LED mounting portion 14 (top cover 12) via the holder 16, and is appropriately positioned by a first positioning member 110, a second positioning member 120, and the like, which will be described later. Since the four LED units 40 are supported by the top cover 12, the top cover 12 can be moved upward from a position close to the photosensitive drum 53 by rotating the top cover 12 upward (not shown). ). The detailed configuration of the LED unit 40 will be described later.

  The process cartridge 50 is arranged side by side between the top cover 12 and the paper feeding unit 20 in the front-rear direction, and a photosensitive drum 53 as an example of a photosensitive member on which an electrostatic latent image is formed, and a reference numeral omitted. The apparatus includes a known charger, a developing roller, a supply roller, a toner container, and the like.

  The transfer unit 70 is provided between the paper feeding unit 20 and each process cartridge 50, and mainly includes a drive roller 71, a driven roller 72, a conveyance belt 73, and a transfer roller 74.

  The driving roller 71 and the driven roller 72 are spaced apart and arranged in parallel in the front-rear direction, and an endless conveyance belt 73 is stretched therebetween. The outer surface of the conveyance belt 73 is in contact with each photoconductive drum 53, and a transfer roller 74 that holds the conveyance belt 73 between each photoconductive drum 53 is opposed to each photoconductive drum 53 on the inner side. Four are arranged. A transfer bias is applied to the transfer roller 74 during transfer.

  The fixing unit 80 is disposed behind each process cartridge 50 and the transfer unit 70, and includes a heating roller 81 and a pressure roller 82 that is disposed to face the heating roller 81 and presses the heating roller 81.

  In the image forming unit 30 configured as described above, first, the surface of each photosensitive drum 53 is uniformly charged by a charger and then exposed to light emitted from each LED unit 40. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on each photosensitive drum 53. Thereafter, toner is supplied from the developing roller to the electrostatic latent image, so that a toner image is formed on each photosensitive drum 53.

  Then, the paper P supplied onto the conveyance belt 73 passes between each photosensitive drum 53 and each transfer roller 74 disposed inside the conveyance belt 73, thereby forming on each photosensitive drum 53. The transferred toner images are sequentially superimposed on the paper P and transferred. Thereafter, as the paper P passes between the heating roller 81 and the pressure roller 82, the toner image transferred onto the paper P is thermally fixed.

  The paper discharge unit 90 mainly includes a paper discharge side transport path 91 formed so as to extend upward from the exit of the fixing unit 80 and change its direction forward, and a plurality of transport rollers 92 that transport the paper P. I have. The sheet P on which the toner image has been thermally fixed is transported along a paper discharge side transport path 91 by a transport roller 92, discharged to the outside of the main body housing 10, and accumulated in the paper discharge tray 13.

  Next, features of the present invention will be described. 2 is a diagram of the LED unit and the configuration around the LED unit as viewed from the front, and FIG. 3 is a diagram of the configuration of the LED unit and the periphery of the LED unit as viewed from the left.

  Here, in the following description, the direction will be described with reference to the state in which the LED unit 40 shown in FIG. In the following description, the “optical axis direction” refers to the optical axis direction of light emitted from the LED unit 40 (LED head 41), and in the present embodiment, substantially coincides with the vertical direction. Furthermore, the “movement direction” refers to the movement direction of the portion of the photosensitive drum 53 that faces the LED unit 40 (LED head 41), and in the present embodiment, substantially coincides with the front-rear direction.

First, the LED unit 40 and its peripheral configuration will be described in detail.
As shown in FIG. 2, the LED unit 40 mainly includes an LED head 41 as an example of an exposure member, a support frame 42, two guide rollers 43, and two eccentric cams 44.

  The LED head 41 includes a plurality of LED arrays 41A arranged in a line in the left-right direction as an example of a plurality of blinking portions, a lens array 41B, and a resin head frame 41C that supports the LED array 41A, the lens array 41B, and the like. And is composed mainly of. The LED head 41 may be configured to have a plurality of columns of LED arrays 41A arranged in the left-right direction.

The LED array 41A is a semiconductor chip and is configured by arranging a plurality of LEDs.
The lens array 41B forms an image of the light emitted from the LED array 41A on the surface of the photosensitive drum 53, and is made of glass as an example of a gradient index lens in which the light emission surface is formed in a planar shape. The GRIN lenses (columnar lenses) are arranged in a line.

  The support frame 42 is a resin member that supports the LED head 41 from above, and is attached to the LED attachment portion 14 via the holder 16 (see FIG. 1). The support frame 42 mainly includes a frame main body 42A and roller support portions 42B extending downward from the left and right ends of the frame main body 42A. The details of the configuration in which the holder 16 supports the support frame 42 will be omitted.

  The frame main body 42A is formed with a recess 42C that is recessed downward from the upper surface above (substantially above) the roller support portions 42B on the left and right ends. In the recess 42 </ b> C, a pressing spring 45 (compression coil spring) as an example of a first pressing member is disposed with its upper end protruding from the upper surface of the support frame 42.

  Since the upper end of the pressing spring 45 is attached to the holder 16 and the lower end is in contact with the bottom surface of the recess 42 </ b> C, the pressing frame 45 presses the support frame 42 (LED unit 40) toward the photosensitive drum 53 when being compressed. It will be. Although not shown in the drawings, wall portions that are integrally provided with the frame main body 42A that is continuous in the vertical direction or discontinuous (for example, in a lattice shape) are formed before and after the concave portion 42C. Thereby, the buckling of the pressing spring 45 is prevented, so that the support frame 42 can be stably pressed toward the photosensitive drum 53.

In the roller support portion 42B, a guide roller 43 is rotatably supported at the lower end.
The guide roller 43 is in contact with the surface of the photoconductive drum 53 when the LED unit 40 is in a position close to the photoconductive drum 53, so that the interval between the LED head 41 and the photoconductive drum 53 is kept constant. It is a holding member. The guide roller 43 is pressed against the photosensitive drum 53 when the pressing force from the pressing spring 45 is transmitted through the support frame 42, and is driven to rotate with respect to the photosensitive drum 53.

  The guide roller 43 may be in contact with a photosensitive layer (a layer on which an electrostatic latent image is formed by exposure) on the surface of the photosensitive drum 53, or an area outside the photosensitive layer (photosensitive layer) in the left-right direction. It may be in contact with a region having no layer.

  Here, as described above, the concave portion 42C is formed above (substantially above) the roller support portion 42B of the frame main body 42A, and the pressing spring that presses the support frame 42 toward the photosensitive drum 53 in the concave portion 42C. 45 is arranged. Therefore, the guide roller 43 is pressed from directly above by the pressing spring 45. Accordingly, deformation (curvature or the like) of the support frame 42 or the LED head 41 due to the pressing force of the pressing spring 45 can be minimized, and therefore the LED unit 40 (specifically, the LED array 41A) with respect to the photosensitive drum 53. The position can be stabilized.

  The eccentric cam 44 is a known eccentric cam disposed between the LED head 41 and the support frame 42 (frame main body 42A). The LED unit 40 can adjust the distance between the LED head 41 and the support frame 42 by appropriately rotating the eccentric cam 44. Note that description of the details of the configuration in which the support frame 42 supports the LED head 41 is omitted.

  The LED unit 40 configured as described above is attached to the photosensitive drum 53 by the first positioning member 110, the second positioning member 120, the third positioning member 130, and the second pressing member 46 provided on the main body frame 15. It is positioned. Hereinafter, the configuration of each member and the positional relationship with the LED unit 40 will be described.

  As shown in FIGS. 2 and 3, the first positioning member 110, the second positioning member 120, and the third positioning member 130 are in contact with the support frame 42 (frame main body 42 </ b> A) of the LED unit 40, respectively. The position of the LED unit 40 is determined in the moving direction (front-rear direction) of the body drum 53.

  The first positioning member 110 is an upper part on the left end side (longitudinal direction one end side) of the LED unit 40 (frame main body 42A) and on the rear side of the LED unit 40 (upstream in the movement direction with respect to the LED unit 40). Has been placed. The first positioning member 110 includes a plate-like base 111 fixed to the main body frame 15 (the inner surface of the left side frame 15A) and a first positioning portion 112 that protrudes from the front surface of the base 111 in a substantially hemispherical shape. Has been.

  The second positioning member 120 is arranged on the left end side of the LED unit 40 (the frame main body 42A) so as to line up with the first positioning member 110 when viewed from the front-rear direction. More specifically, the second positioning member 120 is closer to the photosensitive drum 53 than the first positioning member 110 in the optical axis direction (vertical direction) (below the first positioning member 110), and It is arranged on the front side (downstream in the movement direction with respect to the LED unit 40).

  The second positioning member 120 includes a plate-like base 121 fixed to the main body frame 15 (the inner surface of the left side frame 15A) and a second positioning portion 122 that protrudes substantially hemispherically from the rear surface of the base 121. Has been.

  The third positioning member 130 is the right end side (the other end side in the longitudinal direction) of the LED unit 40 (frame main body 42A), and is the front side of the LED unit 40 that is the same as the second positioning member 120 in the front-rear direction. It is arranged at the same position as the second positioning member in the direction. The third positioning member 130 includes a plate-like base (not shown) that is fixed to the main body frame 15 (the inner surface of the right side frame 15A), and a third positioning portion 132 that protrudes substantially hemispherically from the rear surface of the base. It is composed of

  The second pressing member 46 is mainly composed of an arm portion 46A and a torsion spring 46B. The arm portion 46A is attached so that the upper portion thereof can swing back and forth with respect to the main body frame 15 (left side frame 15A) with the shaft portion 46C as a fulcrum. The arm portion 46A is constantly biased toward the LED unit 40 by the torsion spring 46B, thereby pressing the LED unit 40 toward the second positioning member 120.

  The second pressing member 46 is disposed on the left and right ends of the LED unit 40 (frame body 42A) and on the rear side of the LED unit 40. Specifically, each of the second pressing members 46 at the left and right ends has a pressing portion 46D that presses the LED unit 40, and the second positioning member 120 or the third positioning member 130 sandwiching the LED unit 40 (support frame 42). (Only one side is shown in FIG. 3).

  With the configuration as described above, in the LED unit 40, the second positioning member 120 and the third positioning member 130 are in contact with the front lower portions on both ends of the support frame 42, and the first positioning member 110 is on the left rear upper portion of the support frame 42. By the contact, the position in the front-rear direction with respect to the photosensitive drum 53 is determined. Further, the LED unit 40 is positioned in the vertical direction with respect to the photosensitive drum 53 when the guide roller 43 contacts the surface of the photosensitive drum 53.

  Next, a configuration for stabilizing the position of the LED unit 40 with respect to the photosensitive drum 53 will be described. In the following description, the action point 45A refers to an action point at which the pressing spring 45 presses the LED unit 40 (the bottom surface of the recess 42C of the support frame 42) toward the photosensitive drum 53.

  As shown in FIGS. 2 and 3, the action point 45 </ b> A of the pressing spring 45 is positioned closer to the photosensitive drum 53 than the first positioning member 110 in the vertical direction (lower than the first positioning member 110). Yes. More specifically, the action point 45A is located between the first positioning member 110 (first positioning portion 112) and the second positioning member 120 (second positioning portion 122) in the vertical direction, as viewed from the front-rear direction. The first positioning portion 112, the second positioning portion 122, and the third positioning portion 132 are located within a triangle (see the chain line) region (including the side of the triangle).

  Here, the operation due to the action point 45A of the pressing spring 45 being in the above-described position will be described. FIG. 4 is a diagram for explaining the operation of the present embodiment, and a diagram (a) showing the configuration of the embodiment in which the point of action of the pressing spring is located between the first positioning member and the second positioning member; FIG. 5B is a diagram showing a configuration of a comparative example in which the operating point of the pressing spring is located above the first positioning member, and FIG. 6B is a diagram showing a configuration of a modification in which the operating point of the pressing spring is positioned below the second positioning member. c). In FIG. 4A, the action point 45 </ b> A is illustrated near the center between the first positioning member 110 and the second positioning member 120 for convenience of explanation.

In the structure of this embodiment is shown in FIG. 4 (a), fine vibration is generated in the color printer 1, for example, the force F _R to the point of action 45A is pulled away LED unit 40 deviated rearward from the second positioning member 120 When acting, the LED unit 40 is supported by the first positioning member 110, and the LED unit 40 is restricted from being separated from the positioning member by the pressing force of the second pressing member 46. Thereby, the position of the LED unit 40 in the front-rear direction with respect to the photosensitive drum 53 can be stabilized.

Further, even when the action point 45A is displaced forward and a force F _F that pulls the LED unit 40 away from the first positioning member 110 is applied, the contact between the action point 45A and the second positioning member 120 serving as the center of swinging. Since the distance to the contact portion (fulcrum O1) is short, a relatively large force is required to swing the LED unit 40. Therefore, since the swing of the LED unit 40 is suppressed by a relatively small force due to minute vibrations, the position of the LED unit 40 in the front-rear direction with respect to the photosensitive drum 53 can be stabilized.

  As described above, in the configuration of the present embodiment, even if the action point 45A is shifted forward or backward due to vibration, the action (effect of vibration) of the LED unit 40 being separated from the positioning member is suppressed, and the photoconductor of the LED unit 40 is suppressed. The position in the front-rear direction with respect to the drum 53 can be stabilized.

On the other hand the support, in the configuration of the comparative example shown in FIG. 4 (b), when the point of action 45A force F _R displaced rearward is applied is, LED unit 40 by the first positioning member 110 and the second positioning member 120 Therefore, the position of the LED unit 40 in the front-rear direction is stable. However, when the point of action 45A is a force F _F displaced forwardly so far that the distance between the working point 45A and the fulcrum O1, LED unit 40 is swung in a relatively small force due to fine vibration It will leave | separate from the 1st positioning member 110 (refer chain line). Since it is not possible to control whether the action point 45A is shifted forward or backward due to vibration, if the LED unit 40 moves away from the positioning member, the position of the LED unit 40 relative to the photosensitive drum 53 cannot be stabilized.

In the present invention, the point of action 45A of the pressing spring 45 may be positioned below the second positioning member 120 (on the side closer to the photosensitive drum 53 than the second positioning member 120).
In such a configuration, as shown in FIG. 4 (c), if the point of action 45A is a force F _F shifted forwardly by the LED unit 40 is first positioning member 110 and the second positioning member 120 Since it is supported, the position of the LED unit 40 in the front-rear direction with respect to the photosensitive drum 53 can be stabilized.

Also, when the point of action 45A force F _R displaced backward is applied, since the closer the distance between the pressing portion 46D of the second pressing member 46 serving as a working point 45A and the swing center, the LED unit 40 rocking To move it, a relatively large force is required. Therefore, since the swing of the LED unit 40 is suppressed by a relatively small force due to minute vibrations, the position of the LED unit 40 in the front-rear direction with respect to the photosensitive drum 53 can be stabilized.

  However, in this case, since the distance between the action point 45A and the fulcrum O2 is long, the effect that the first positioning member 110 supports the LED unit 40 cannot be expected. Therefore, as in the present embodiment, the configuration in which the action point 45A is located between the first positioning member 110 and the second positioning member 120 can most stabilize the position of the LED unit 40 with respect to the photosensitive drum 53. .

According to the above, the following effects can be obtained in the present embodiment.
The action point 45A of the pressing spring 45 is positioned closer to the photosensitive drum 53 than the first positioning member 110 in the vertical direction (specifically, between the first positioning member 110 and the second positioning member 120). Therefore, even if the action point 45A is shifted in any of the front and rear directions due to vibration, the action of the LED unit 40 separating from the positioning member can be suppressed, and the position of the LED unit 40 relative to the photosensitive drum 53 can be stabilized. As a result, the positions of the LED head 41 (LED array 41A) and the photosensitive drum 53 can be stabilized, so that it is possible to suppress deterioration in image quality in the color printer 1.

  The first positioning member 110 is disposed on the upper rear side of the LED unit 40, the second positioning member 120 is disposed on the lower front side of the LED unit 40, and the pressing portion 46 </ b> D of the second pressing member 46 sandwiches the LED unit 40 in the second positioning. Since the LED 120 is disposed so as to face the member 120, even if the counterclockwise force of FIG. 3 acts on the LED unit 40, it can be regulated by the first positioning member 110 and the second positioning member 120. . Thereby, the position of the LED unit 40 with respect to the photosensitive drum 53 can be stabilized.

  In the present embodiment, the configuration in which the pressing portion 46D of the second pressing member 46 is disposed so as to face the second positioning member 120 with the LED unit 40 interposed therebetween is shown, but the present invention is limited to this. It is not a thing. For example, it is good also as a structure arrange | positioned so that the part which presses the exposure unit of a 2nd press member may be located in the side near a photoconductor rather than a 2nd positioning member. According to this, since the second pressing member applies a force that rotates counterclockwise in FIG. 3 to the exposure unit (LED unit 40), the exposure unit is directed toward the first positioning member and the second positioning member. Is energized. Thereby, the position of the LED unit 40 relative to the photosensitive drum 53 can be further stabilized.

  The action point 45A of the pressing spring 45 is located in a triangular area formed by the first positioning part 112, the second positioning part 122, and the third positioning part 132 when viewed from the front-rear direction, so that the LED unit 40 is The force that rotates around the sides of the triangle can be minimized.

  The action point 45A of the pressing spring 45 is on the support frame 42 (the bottom surface of the recess 42C), and the first positioning member 110 and the second positioning member 120 are in contact with the support frame 42, so that force acts on the LED head 41. Can be prevented. Thereby, deformation of the LED head 41 that requires high positional accuracy with respect to the photosensitive drum 53 can be prevented, so that the positional accuracy between the LED array 41A and the photosensitive drum 53 can be maintained. The image quality of the color printer 1 can be improved.

  In the present embodiment, the first positioning member 110 is disposed on the rear side (upstream side in the movement direction) of the LED unit 40, and the second positioning member 120 is disposed on the front side (downstream side in the movement direction) of the LED unit 40. However, the present invention is not limited to this. That is, the first positioning member may be arranged on the downstream side in the movement direction, and the second positioning member may be arranged on the upstream side in the movement direction.

[Second Embodiment]
Next, a second embodiment of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 5 is a diagram of the LED unit and the configuration around the LED unit according to the second embodiment as viewed from the left, and FIG. 6 is a diagram of the configuration of the LED unit and the periphery of the LED unit as viewed from the front. The second embodiment is mainly different from the first embodiment in the configuration around the LED unit and the position of the action point. Therefore, this point will be described in detail, and the same components are denoted by the same reference numerals. The description will be omitted.

  In the present embodiment, the LED unit 40 is positioned with respect to the photosensitive drum 53 by a positioning member 140, a third positioning member 130 and a second pressing member 46 provided on the main body frame 15.

  As shown in FIGS. 5 and 6, the positioning member 140 is on the left end side (one longitudinal end side) of the LED unit 40 (frame main body 42 </ b> A) and on the front side of the LED unit 40 (with respect to the LED unit 40). It is arranged on the downstream side in the movement direction. The positioning member 140 includes a plate-like base portion 141 that is vertically fixed to the main body frame 15 (the inner surface of the left side frame 15A), and a first positioning portion 112 that protrudes in a substantially hemispherical shape from the upper rear surface of the base portion 141. The second positioning portion 122 protrudes substantially hemispherically from the lower portion of the rear surface of the base portion 141.

  The third positioning member 130 is the right end side (the other end in the longitudinal direction) of the LED unit 40 (frame main body 42A) and the front side of the LED unit 40 that is the same as the positioning member 140 in the front-rear direction, and is the first in the vertical direction. Between the positioning part 112 and the second positioning part 122, it is arranged substantially at the center. The third positioning member 130 includes a plate-like base (not shown) that is fixed to the main body frame 15 (the inner surface of the right side frame 15A), and a third positioning portion 132 that protrudes substantially hemispherically from the rear surface of the base. It is composed of

  In the present embodiment, the second pressing member 46 is disposed on the left and right ends of the LED unit 40 and on the rear side of the LED unit 40. Specifically, the second pressing member 46 on the left end side has a pressing portion 46D that presses the LED unit 40 at a position facing the positioning member 140 across the LED unit 40, and the first positioning portion 112 and the second positioning member 112 in the vertical direction. It arrange | positions so that it may be located in the approximate center between 2 positioning parts 122. Although not shown, the second pressing member 46 on the right end side is arranged such that a pressing portion 46D that presses the LED unit 40 faces the third positioning member 130 with the LED unit 40 interposed therebetween.

  With the configuration as described above, in the LED unit 40 of the second embodiment, the first positioning portion 112 and the second positioning portion 122 of the positioning member 140 are in contact with the upper and lower left sides of the support frame 42, and the third positioning portion 132 is The position in the front-rear direction with respect to the photosensitive drum 53 is determined by contacting the center of the support frame 42 after the right end.

  In the present embodiment, the action point 45 </ b> A of the pressing spring 45 is positioned approximately at the center between the first positioning portion 112 and the second positioning portion 122 in the vertical direction. More specifically, as shown in FIG. 6, the action point 45 </ b> A is within a triangular region (see the chain line) formed by the first positioning portion 112, the second positioning portion 122, and the third positioning portion 132 when viewed from the front-rear direction. (Including on the side of the triangle).

  Here, in the present embodiment, an operation due to the fact that the operating point 45A of the pressing spring 45 is in the above-described position will be described. FIG. 7 is a diagram for explaining the operation of the present embodiment, and FIG. 7A is a diagram showing the configuration of the embodiment in which the point of action of the pressing spring is located between the first positioning member and the second positioning member; FIG. 7B shows the configuration of the first comparative example in which the operating point of the pressing spring is located above the first positioning member, and the configuration of the second comparative example in which the operating point of the pressing spring is positioned below the second positioning member. FIG.

In the structure of this embodiment is shown in FIG. 7 (a), fine vibration is generated, if the point of action 45A is a force F _F displaced forwardly, LED unit 40 and the first positioning portion 112 Supported by the second positioning portion 122. Also, when the point of action 45A force F _R displaced rearward is applied is, LED unit 40 is departing from the positioning unit (positioning member) is regulated by the pressing force of the second pressing member 46. Thereby, the position of the LED unit 40 in the front-rear direction with respect to the photosensitive drum 53 can be stabilized.

  As described above, in the configuration of the present embodiment, even if the action point 45A is shifted forward or backward due to vibration, the action (effect of vibration) of the LED unit 40 being separated from the positioning member is suppressed, and the photoconductor of the LED unit 40 is suppressed. The position in the front-rear direction with respect to the drum 53 can be stabilized.

  On the other hand, the configuration of the first comparative example in which the action point 45A shown in FIG. 7B is located above the first positioning portion 112, and the action point 45A shown in FIG. In the configuration of the second comparative example located at, the position of the LED unit 40 relative to the photosensitive drum 53 cannot be stabilized.

That In FIG. 7 (b) and FIG. 7 (c), the if the point of action 45A is a force F _F displaced forwardly, fulcrum O3 serving as a working point 45A and the swing center (or fulcrum O4) Therefore, the LED unit 40 is less likely to swing even with a relatively small force due to minute vibrations. However, in the case where the pressing portion 46D is positioned closer to the first positioning portion 112 in FIG. 7B or the pressing portion 46D is positioned closer to the second positioning portion 122 in FIG. Thus, the second pressing member 46 can be swung with a smaller force than when the pressing portion 46D is directly pressed. Therefore, the position of the LED unit 40 may become unstable as compared with the configuration of the present embodiment.

Also, when the point of action 45A force F _R displaced backward is applied, since the distance between the pressing portion 46D of the second pressing member 46 serving as a working point 45A and the swinging center becomes longer, LED unit 40 The position of the LED unit 40 is not stable because it swings away from the first positioning part 112 (or the second positioning part 122) even with a relatively small force due to minute vibrations.
As described above, in the configurations of the first comparative example and the second comparative example, the position of the LED unit 40 with respect to the photosensitive drum 53 cannot be stabilized.

According to the above, the following effects can be obtained in the present embodiment.
The first positioning portion 112 and the second positioning portion 122 are disposed on the front side of the LED unit 40, and the pressing portion 46D of the second pressing member 46 is positioned between the first positioning portion 112 and the second positioning portion 122 in the vertical direction. Therefore, the action of the LED unit 40 separating from the positioning member can be suppressed, and the position of the LED unit 40 relative to the photosensitive drum 53 can be stabilized. Thereby, it is possible to suppress a decrease in image quality in the color printer 1.

  The action point 45A of the pressing spring 45 is located in a triangular area formed by the first positioning part 112, the second positioning part 122, and the third positioning part 132 when viewed from the front-rear direction, so that the LED unit 40 is The force that rotates around the sides of the triangle can be minimized.

  In the present embodiment, the positioning member 140 (the first positioning portion 112 and the second positioning portion 122) is disposed on the front side (downstream in the moving direction) of the LED unit 40. It is not limited to. That is, the first positioning member and the second positioning member may be arranged on the upstream side in the movement direction.

  Moreover, in this embodiment, although the positioning member 140 (the 1st positioning part 112 and the 2nd positioning part 122) showed the structure arrange | positioned at the left end side of the LED unit 40, this invention is not limited to this. Absent. That is, the first positioning member and the second positioning member may be arranged on the right end side of the LED unit 40.

[Third Embodiment]
Next, a third embodiment of the present invention will be described in detail with reference to the drawings as appropriate. FIG. 8 is a view of the LED unit according to the third embodiment and the configuration around the LED unit as viewed from the left. Note that this embodiment is different from the second embodiment only in that the fourth positioning member 150 is employed instead of the positioning member 140 described above. Therefore, this point will be described, and similar constituent elements will be denoted by the same reference numerals. The description is omitted.

  As shown in FIG. 8, the fourth positioning member 150 is fixed to the main body frame 15 (the inner surface of the left side frame 15A) and is formed in a long plate shape having a predetermined length in the vertical direction. The fourth positioning member 150 determines the position of the LED unit 40 in the front-rear direction when the positioning surface 152 as a rear surface comes into surface contact with the LED unit 40 (support frame 42).

  In the present embodiment, the second pressing member 46 on the left end side faces the fourth positioning member 150 with the LED unit 40 interposed therebetween, specifically, approximately the center between the upper end and the lower end of the fourth positioning member 150. The LED unit 40 is pressed toward the fourth positioning member 150.

  In the present embodiment, the action point 45A of the pressing spring 45 is positioned at the approximate center within the outer frame of the area where the LED unit 40 (support frame 42) and the fourth positioning member 150 are in surface contact when viewed from the front-rear direction. is doing.

According to the above, an effect equivalent to that of the second embodiment described above can be obtained in this embodiment.
Further, since the fourth positioning member 150 and the LED unit 40 are in surface contact, the LED unit 40 can be supported more stably.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  The configuration of each positioning member 110, 120, 130, 140, 150 shown in the above embodiment is an example, and the present invention is not limited to this. That is, each positioning member can be appropriately changed without departing from the gist of the present invention as long as the positioning member 110, 120, 130, 140, 150 has the same effect as the positioning member 110 described above.

  In the above-described embodiment, an example in which the pressing spring 45 (compression coil spring) is adopted as an example of the first pressing member has been described. However, the present invention is not limited to this, and for example, a predetermined other than a torque spring, a leaf spring, or a spring You may employ | adopt the material, member, etc. which have elasticity.

In the above-described embodiment, the second pressing member 46 is disposed so as to face the positioning member with the LED unit 40 interposed therebetween, but the present invention is not limited to this. For example, in the first embodiment described above, only one second pressing member may be arranged at the approximate center between the second positioning member 120 and the third positioning member 130 when viewed from the front-rear direction. Further, in the second embodiment described above, the second pressing member is positioned at the approximate center of the perpendicular extending from the third positioning portion 132 to the side connecting the first positioning portion 112 and the second positioning portion 122 when viewed from the front-rear direction. It is good also as a structure which arranges only one.

  The second pressing member “presses the exposure unit toward the second positioning member” means that the exposure unit is pressed toward at least the second positioning member, and the exposure unit is moved by the second pressing member. This is not intended to exclude the configuration in which the first positioning member and the third positioning member are also pressed. Further, three or more second pressing members may be provided for one exposure unit.

  The structure of the 2nd press member 46 shown by above-described embodiment is an example, and this invention is not limited to this. That is, the second pressing member can be appropriately changed without departing from the gist of the present invention as long as the second pressing member is configured to exhibit the same function as the second pressing member 46 described above. For example, the second pressing member may be a coil spring, a leaf spring, or a material or member having a predetermined elasticity other than the spring.

  In the above-described embodiment, an example in which the LED array 41A in which a plurality of LEDs are arranged is adopted as an example of the blinking portion is shown. However, the present invention is not limited to this, and for example, an EL (electroluminescence) element or a fluorescent light is used. The body may be used. Further, the number of light-emitting elements may be one to form the plurality of blinking portions. For example, one backlight such as a fluorescent lamp may be arranged, and an optical shutter such as an arranged liquid crystal element or PLZT element may be provided on the emission side of the backlight. That is, a plurality of blinking portions can be configured by combining one light emitting element and an arrayed optical shutter.

  In the above-described embodiment, the example in which the LED unit 40 (exposure unit) is mainly configured by the LED head 41 (exposure member) and the support frame 42 has been described, but the configuration of the exposure unit of the present invention is particularly limited. is not. For example, the exposure member and the support frame may be integrated (one component).

  In the above-described embodiment, the photosensitive drum 53 is illustrated as an example of the photosensitive member, but the present invention is not limited to this, and may be, for example, a photosensitive belt.

  In the above-described embodiment, the color printer 1 is shown as an example of the image forming apparatus. However, the present invention is not limited to this, and may be, for example, a color copying machine or a color complex machine. In the above-described embodiment, an image forming apparatus (color printer 1) capable of forming a color image has been described. However, the present invention is not limited to this, and a printer, a copier, a multifunction machine, or the like that forms a monochrome image. It may be.

  In the present invention, “between the first positioning member and the second positioning member in the optical axis direction” includes the same position (overlapping position) as the first positioning member or the second positioning member in the optical axis direction. . Further, “within a triangular region formed by the first positioning member, the second positioning member, and the third positioning member” includes a position that overlaps a side of the triangle as viewed from the moving direction of the photosensitive member. Further, “within the range of the outer frame in the area where the exposure unit and the fourth positioning member are in surface contact” includes the position overlapping the outer frame as viewed from the moving direction of the photosensitive member.

1 is a cross-sectional view illustrating an overall configuration of a color printer as an example of an image forming apparatus. It is the figure which looked at the structure around the LED unit and LED unit from the front. It is the figure which looked at the structure around an LED unit and LED unit from the left. It is a figure for demonstrating the effect | action of 1st Embodiment, The figure (a) which shows the structure of embodiment which the action point of a press spring is located between a 1st positioning member and a 2nd positioning member, and a press spring (B) which shows the structure of the comparative example in which the action point of this is located above the 1st positioning member, and the figure (c) which shows the structure of the modification in which the action point of a press spring is located below the 2nd positioning member It is. It is the figure which looked at the structure of LED unit of 2nd Embodiment and LED unit periphery from the left. It is the figure which looked at the structure of LED unit of 2nd Embodiment and LED unit periphery from the front. It is a figure for demonstrating the effect | action of 2nd Embodiment, the figure (a) which shows the structure of embodiment which the action point of a press spring is located between a 1st positioning member and a 2nd positioning member, and a press spring (B) which shows the structure of the 1st comparative example in which the action point of this is located above the 1st positioning member, and the structure of the 2nd comparative example in which the action point of a press spring is located below the 2nd positioning member It is a figure (c). It is the figure which looked at the LED unit of 3rd Embodiment and the structure of LED unit periphery from the left.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 40 LED unit 41 LED head 41A LED array 42 Support frame 45 Press spring 45A Action point 46 2nd press member 53 Photosensitive drum 110 1st positioning member 112 1st positioning part 120 2nd positioning member 122 2nd positioning part 130 3rd positioning member 132 3rd positioning part 150 4th positioning member 152 Positioning surface

Claims (10)

A photoreceptor on which an electrostatic latent image is formed;
An exposure unit that exposes the photoreceptor with a plurality of blinking portions;
A first pressing member that presses the exposure unit toward the photoreceptor;
A first positioning member that determines a position of the exposure unit in a moving direction of a portion of the photoconductor facing the exposure unit by contacting the exposure unit;
The exposure unit is positioned closer to the photoconductor than the first positioning member in the optical axis direction of the light emitted from the exposure unit, and abuts the exposure unit to position the exposure unit in the movement direction. A second positioning member to be determined;
A second pressing member that presses the exposure unit toward the side on which the second positioning member is disposed in the moving direction ;
A third positioning member that determines the position of the exposure unit in the moving direction by contacting the exposure unit;
An interval holding member that maintains a constant interval between the exposure unit and the photoconductor by contacting the surface of the photoconductor;
The first positioning member and the second positioning member are arranged at one end side in the longitudinal direction of the exposure unit, and one is arranged on the upstream side in the moving direction with respect to the exposure unit, and the other is downstream in the moving direction. Is located on the side,
The third positioning member is the other end side in the longitudinal direction of the exposure unit, and is disposed on the same side as the second positioning member among the upstream side and the downstream side in the moving direction,
The image forming apparatus according to claim 1, wherein an action point at which the first pressing member presses the exposure unit is located closer to the photoconductor than the first positioning member in the optical axis direction.   The image forming apparatus according to claim 1, wherein the action point is located between the first positioning member and the second positioning member in the optical axis direction. Before SL portion where the second pressing member for pressing the exposure unit is either in a position facing the second positioning member across said exposure unit, or the second side closer to the photoreceptor than the positioning member The image forming apparatus according to claim 2, wherein the image forming apparatus is located in the position. Before Symbol third positioning member is disposed between the second positioning member and the first positioning member before Kihikarijiku direction,
The said action point is located in the area | region of the triangle formed by the said 1st positioning member, the said 2nd positioning member, and the said 3rd positioning member seeing from the said moving direction. The image forming apparatus described. A photoreceptor on which an electrostatic latent image is formed;
An exposure unit that exposes the photoreceptor with a plurality of blinking portions;
A first pressing member that presses the exposure unit toward the photoreceptor;
A first positioning member that determines a position of the exposure unit in a moving direction of a portion of the photoconductor facing the exposure unit by contacting the exposure unit;
The exposure unit is positioned closer to the photoconductor than the first positioning member in the optical axis direction of the light emitted from the exposure unit, and abuts the exposure unit to position the exposure unit in the movement direction. A second positioning member to be determined;
A second pressing member that presses the exposure unit toward the side on which the second positioning member is disposed in the moving direction;
A third positioning member that determines the position of the exposure unit in the moving direction by contacting the exposure unit;
An interval holding member that keeps the interval between the exposure unit and the photosensitive member constant by contacting the surface of the photosensitive member;
The first positioning member and the second positioning member are arranged at one end side in the longitudinal direction of the exposure unit, either upstream or downstream in the moving direction with respect to the exposure unit,
The third positioning member is the other end side in the longitudinal direction of the exposure unit, and is arranged on the same side as the first positioning member and the second positioning member among the upstream side and the downstream side in the moving direction,
The image forming apparatus according to claim 1, wherein an action point at which the first pressing member presses the exposure unit is located closer to the photoconductor than the first positioning member in the optical axis direction. The image forming apparatus according to claim 5, wherein the action point is located between the first positioning member and the second positioning member in the optical axis direction. Before SL portion where the second pressing member for pressing the exposure unit according to claim 6, characterized in that located between the second positioning member and the first positioning member in the optical axis direction Image forming apparatus. Before Symbol third positioning member is disposed between the second positioning member and the first positioning member before Kihikarijiku direction,
The working point, the first positioning member when viewed from the direction of movement, to claim 7, characterized in that it is positioned in the second positioning member and the third area of the triangle formed by the positioning member The image forming apparatus described. The exposure unit includes an exposure member having the plurality of blinking portions, and a support frame that supports the exposure member,
The said action point exists in the said support frame, The said 1st positioning member , the said 2nd positioning member, and the said 3rd positioning member contact | abut to the said support frame, The any one of Claims 1-8 characterized by the above-mentioned. The image forming apparatus described in the item. A photoreceptor on which an electrostatic latent image is formed;
An exposure unit that exposes the photoreceptor with a plurality of blinking portions;
A first pressing member that presses the exposure unit toward the photoreceptor;
The exposure unit has a predetermined length in the optical axis direction of the light emitted from the exposure unit, and is in surface contact with the exposure unit so that the exposure unit has a moving direction of a portion facing the exposure unit. A fourth positioning member for determining the position;
A second pressing member disposed at a position facing the fourth positioning member across the exposure unit, and pressing the exposure unit toward the fourth positioning member ;
An interval holding member that maintains a constant interval between the exposure unit and the photoconductor by contacting the surface of the photoconductor;
The action point at which the first pressing member presses the exposure unit is within a region where the exposure unit and the fourth positioning member are in surface contact as seen from the moving direction , or an outer frame portion of the surface contact region. An image forming apparatus, wherein

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