JP5163712B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that performs exposure with an LED head having a plurality of LEDs (light emitting diodes).

  In general, an image forming apparatus irradiates a charged photosensitive drum with light to form an electrostatic latent image on the photosensitive drum, and supplies a developer to the electrostatic latent image. By transferring to the recording sheet, a predetermined image is formed on the recording sheet. As such an image forming apparatus, conventionally, an LED head having a plurality of LEDs for irradiating light to a photosensitive drum, and a pair of main body frames that support both ends of the LED head in the longitudinal direction (LED arrangement direction). What is provided is known (see Patent Document 1).

Japanese Patent Laid-Open No. 61-95956

  In the prior art, however, it is necessary to position the LED head so as not to move in the longitudinal direction with respect to the main body frame so that the light irradiation position in the axial direction of the photosensitive drum does not shift.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can position an exposure member in a longitudinal direction with respect to a main body frame.

The present invention that solves the above-described problems includes a photosensitive drum, an exposure member that is disposed opposite to the photosensitive drum, and in which a plurality of light emitting portions are arranged in the longitudinal direction to expose the photosensitive drum, and on both longitudinal sides of the exposure member. An image forming apparatus including a main body frame arranged on the main body frame, wherein the main body frame is provided with a reference portion that contacts with one end portion in the longitudinal direction of the exposure member and positions the exposure member in the longitudinal direction. In addition, the main body frame or the exposure member is arranged on the one end portion side in the longitudinal direction, and presses the exposure member in the longitudinal direction so that the one end portion in the longitudinal direction is pulled toward the reference portion. A member is provided.

  According to the present invention, since the one end of the exposure member is pressed against the reference portion of the main body frame by the pressing member, the exposure member can be positioned in the longitudinal direction with respect to one main body frame.

  According to the present invention, since the one end of the exposure member is pressed against the reference portion of the main body frame by the pressing member, the exposure member can be positioned in the longitudinal direction with respect to one main body frame.

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 an overall configuration of a color printer as an example of an image forming apparatus, FIG. 2 is an enlarged view of an LED unit and a process cartridge in FIG. a) is an exploded perspective view of the LED unit, (b) is an enlarged perspective view of the guide roller, FIG. 4 is a side view showing the positional relationship between the LED unit and the side plate, and FIG. It is the figure which looked at the photosensitive drum and LED unit from back.

  Here, in the following description, the direction will be described with reference to the user when using the color printer. That is, in FIG. 1, the left side toward the paper surface is “front side (front side)”, the right side toward the paper surface is “rear side (back side)”, the back side toward the paper surface is “left side”, and it faces the paper surface. Let the near side be the “right side”. In addition, the vertical direction toward the page is defined as the “vertical direction”.

  As shown in FIG. 1, the color printer 1 includes a paper feeding unit 20 that supplies paper P, an image forming unit 30 that forms an image on the fed paper P, and an image formed in a main body housing 10. And a paper discharge unit 90 for discharging the paper P.

  An upper cover 12 that can be opened and closed relative to the main body housing 10 is provided on the upper portion of the main body housing 10 so as to be rotatable up and down around a hinge 12A provided on the rear side. The upper surface of the upper cover 12 serves as a paper discharge tray 13 for accumulating the paper P discharged from the main body housing 10, and a plurality of LED attachments for holding an LED unit 40 as an example of an exposure member to be described later are mounted on the lower surface. A member 14 is provided.

  A main body frame 15 is provided in the main body casing 10 as a part of an apparatus main body that detachably accommodates each process cartridge 50 described later. The main body frame 15 is provided with a pair of metal side frames 15A (only one side is shown) provided on the left and right sides and a cross member 15B connecting the pair of side frames 15A on the front and rear. The main body frame 15 is fixed to the main body housing 10 or the like. The side frames 15A are arranged on both sides of the arrangement direction of light emitting parts of the LED head 41 (to be described later) (referred to as the main direction, which is the same as the axial direction of the photosensitive drum 53 in the present embodiment), and the photosensitive drum 53 is directly attached to the side frames 15A. It is a member that supports and positions automatically or indirectly.

  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. A supply mechanism 22 is mainly provided. The paper supply mechanism 22 is provided on the front side of the paper supply tray 21 and mainly includes a paper supply roller 23, a separation roller 24, and a separation pad 25.

  In the paper feed unit 20 configured in this way, the paper P in the paper feed tray 21 is separated one by one and sent upward, and passes through between the paper dust removal roller 26 and the pinch roller 27 in the process. After the powder is removed, 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 four LED units 40 as an example of an exposure member, four process cartridges 50, a transfer unit 70, and a fixing unit 80.

  The process cartridge 50 is arranged side by side in the front-rear direction between the upper cover 12 and the paper feeding unit 20, and as shown in FIG. 2, the drum unit 51 and the developing unit 61 that is detachably attached to the drum unit 51. And. The process cartridge 50 is supported on the side frame 15 </ b> A, and the photosensitive drum 53 is supported on the process cartridge 50. Each process cartridge 50 has the same configuration except that the color of the toner stored in the toner storage chamber 66 of the developing unit 61 is different.

  The drum unit 51 mainly includes a drum frame 52, a photosensitive drum 53 as an example of a photosensitive member rotatably supported by the drum frame 52, and a scorotron charger 54.

  The developing unit 61 includes a developing frame 62, a developing roller 63 and a supply roller 64 that are rotatably supported by the developing frame 62, and a layer thickness regulating blade 65. The developing unit 61 includes a toner storage chamber 66 that stores toner. Yes. The process cartridge 50 has an exposure hole 55 formed between the developing frame 62 and the drum frame 52 when the developing unit 61 is mounted on the drum unit 51. A drum 53 is disposed. Then, the LED unit 40 is inserted into the exposure hole 55 so that the LED unit 40 is disposed to face the photosensitive drum 53.

  As shown in FIG. 1, 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 arranged in parallel in a spaced manner in the front-rear direction, and a conveyance belt 73 formed of an endless belt is stretched between them. The outer surface of the conveyance belt 73 is in contact with each photosensitive drum 53. In addition, four transfer rollers 74 that sandwich the conveyor belt 73 between the photosensitive drums 53 are arranged inside the conveyor belt 73 so as to face the photosensitive drums 53. A transfer bias is applied to the transfer roller 74 by constant current control during transfer.

  The fixing unit 80 is disposed on the back side of 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 the scorotron charger 54 and then exposed to the LED 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.

  In addition, the toner in the toner storage chamber 66 is supplied to the developing roller 63 by the rotation of the supply roller 64, and enters between the developing roller 63 and the layer thickness regulating blade 65 by the rotation of the developing roller 63 and has a constant thickness. It is carried on the developing roller 63 as a thin layer.

  The toner carried on the developing roller 63 is supplied to the electrostatic latent image formed on the photosensitive drum 53 when the developing roller 63 comes into contact with the photosensitive drum 53. As a result, the toner is selectively carried on the photosensitive drum 53 to visualize the electrostatic latent image, and a toner image is formed by reversal development.

Next, the paper P supplied onto the conveyor belt 73 passes between each photosensitive drum 53 and each transfer roller 74 disposed inside the conveyor belt 73, thereby forming the sheet P on each photosensitive drum 53. The toner image is transferred onto the paper P.
Then, 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 outlet of the fixing unit 80 and to be reversed to the front side, and a plurality of pairs of transport rollers 92 that transport the paper P. I have. The paper P on which the toner image has been transferred and heat-fixed is transported through a paper discharge-side transport path 91 by a transport roller 92, discharged outside the main body housing 10, and accumulated in the paper discharge tray 13.

<Configuration of LED unit>
Next, the LED unit 40, which is a characteristic part of the present invention, and its grounding configuration will be described in detail.
As shown in FIG. 3, the LED unit 40 includes an LED head 41 as an example of an exposure member body, an exposure device frame 42 as an example of a holding member, a roller support member 43, a guide roller 44, and a resin cover 45. And a suspender 48.

  The LED head 41 is formed by arranging a plurality of light emitting units made of LEDs on the lower side in a line in the left-right direction (longitudinal direction of the LED head 41). More specifically, the LED head 41 is arranged according to a predetermined pixel pitch, and is a head structure in which a plurality of LEDs (light emitting elements) that are selectively driven and expose the surface of the photosensitive drum 53 are supported by a support. It is what has. In this specification, the longitudinal direction of the LED head 41 is referred to as a main direction, and is a direction orthogonal to the main direction and the LED exposure direction (see arrow X in FIG. 5), specifically, a direction in which the photosensitive drums 53 are arranged. The front-rear direction is referred to as the sub direction. The exterior of the LED head 41 is made of resin, and discharge from high voltage components such as the scorotron charger 54 is suppressed. Each light emitting unit emits light upon receiving a signal from a control device (not shown) based on data of an image to be formed, and exposes the photosensitive drum 53.

  The exposure unit frame 42 is a frame that supports the LED head 41. The exposure device frame 42 is formed by pressing a metal plate into a substantially U-shaped cross section, and has conductivity. The exposure device frame 42 is formed longer than the LED head 41 in the axial direction of the photosensitive drum 53, that is, in the left-right direction. Specifically, in the exposure unit frame 42, a lower plate 42A, a side plate 42B, and an upper plate 42C form a member having a U-shaped cross section that extends in the left-right direction. End plates 42D are formed at both ends in the left and right direction of the lower plate 42A (hereinafter simply referred to as “both ends”) by bending the end portions of the lower plate 42A. In the upper plate 42C, an opening 42E that opens to the front side is formed near both ends. An engaging claw 42F extending toward the inner side in the left-right direction of the opening 42E is formed at the opening end on the front side of the opening 42E so as to narrow the opening 42E. The upper surface of the LED head 41 is in close contact with the lower plate 42A of the exposure device frame 42, and is attached and fixed to the exposure device frame 42 by two clips 41A.

  The right end of the upper plate 42C of the exposure device frame 42 is pressed to urge the right end portion of the LED head 41 so as to be pulled toward the side frame 15A (for details, the abutting portion 161B of the front guide 161 described later; see FIG. 5). A leaf spring 100 as an example of a member is provided. The leaf spring 100 is formed by bending a conductive metal plate into a substantially L shape, and includes a first wall 101 and a second wall 102. Since the plate spring 100 is provided on the exposure device frame 42 in this way, the plate spring 100 moves from the top to the bottom toward the abutting portion 161B described later as the LED unit 40 moves to the exposure position. By doing so, it is comprised so that the one end part (main direction positioning surface 45D mentioned later) of the LED unit 40 may be pressed against the abutting part 161B.

  The first wall 101 is formed in a flat plate shape and has a width that can be inserted into a through-hole 45B (see the left resin cover 45) of the resin cover 45 described later. The first wall 101 is inserted from the outside of the through hole 45B of the resin cover 45 and fixed to the upper surface of the upper plate 42C of the exposure device frame 42.

As shown in FIG. 5, the second wall 102 has a distal end portion 103 and a main body portion 104.
The main body 104 of the second wall 102 has a side frame 15A (first vertical wall A1) so as to gradually approach the exposure unit frame 42 as it goes downward in a state where the first wall 101 is fixed to the exposure unit frame 42. It is inclined with respect to. Further, the distal end portion 103 of the second wall 102 is inclined with respect to the side frame 15A (first vertical wall A1) so as to move away from the exposure device frame 42 as it goes downward. Therefore, when the LED unit 40 is moved from the retracted position to the exposure position, if the tip 103 of the second wall 102 comes into contact with a first vertical wall A1 of a side frame 15A described later, the first vertical wall A1 The second wall 102 is pushed outward.

  As shown in FIG. 3A, the roller support member 43 is a bracket formed by pressing a conductive metal plate, and is screwed to end plates 42 </ b> D at both ends of the exposure device frame 42. The roller support member 43 is provided with a roller shaft 43A that extends toward the inner side in the left-right direction at the lower end. The roller shaft 43A is a shaft that rotatably supports the guide roller 44, and an engagement groove 43B is formed in the circumferential direction as shown in FIG.

  The guide roller 44 is a substantially cylindrical roller as an example of an abutting portion, and maintains a distance between the LED head 41 and the photosensitive drum 53. That is, the rolling surface 44A is formed in a cylindrical shape. A shaft hole 44B that fits with the roller shaft 43A is formed in the central axis of the rolling surface 44A. The guide roller 44 is attached to the roller shaft 43A by engaging the clip 44D with the engaging groove 43B after the shaft hole 44B is inserted into the roller shaft 43A and the washer 44C is further inserted. That is, the direction in which the roller shaft 43 </ b> A extends coincides with the rotation axis direction of the guide roller 44.

As shown in FIG. 2, the guide roller 44 rolls in contact with the circumferential surface 53 </ b> A of the photosensitive drum 53 to define the positional relationship between the LED unit 40 and the photosensitive drum 53, specifically, the light emitting portion of the LED head 41. It defines the interval between the peripheral surfaces 53A. The material constituting the guide roller 44 is not particularly limited, but it is preferable to use a material having an appropriate friction coefficient with the peripheral surface 53A and having excellent wear resistance. For example, a polyamide-based resin can be used.
In order not to affect image formation, the guide roller 44 is disposed outside the image forming range (indicated by symbol W in FIG. 5) to which toner is supplied, on the peripheral surface 53A of the photosensitive drum 53. Yes.

  As shown in FIG. 3A, the resin cover 45 is a member that covers the metal portions at both ends of the exposure device frame 42. The resin covers 45 provided in total on the left and right are formed symmetrically with each other. The resin cover 45 is made of an insulating resin member, and is formed so as to cover both end faces of the exposure unit frame 42 and a predetermined range from both ends. A guide rib 45 </ b> A extending in the vertical direction protrudes from the outer end of the resin cover 45 in the horizontal direction. The upper end of the guide rib 45A has a substantially triangular outline when viewed from the left and right end sides, and a through hole 45B is formed inside the triangular portion. And the 1st wall 101 of the leaf | plate spring 100 mentioned above is inserted in the through-hole 45B (not shown) of the resin cover 45 arrange | positioned on the right side.

  The outer surface in the left-right direction of the guide rib 45A is a main direction positioning surface 45D. The main direction positioning surface 45D is for abutting the side frame 15A in the main direction to position the LED unit 40 in the main direction. The front surface of the guide rib 45A is a sub-direction positioning surface 45E. The sub-direction positioning surface 45E is for abutting the side frame 15A in the sub-direction to position the LED unit 40 in the sub-direction.

  The suspender 48 is a member that supports the exposure device frame 42 and the LED head 41 in a suspended state. The suspender 48 has a length in the left-right direction equivalent to that of the exposure device frame 42, and is provided with engagement members 48A at two locations corresponding to the two openings 42E. Each of the engaging members 48A is formed with a U-shaped cross-section that opens outward in the left-right direction when viewed from below, and the U-shaped opening 48B has play with the engaging claw 42F. It is designed to engage.

A compression spring 49 as an example of a first urging member is disposed between each engaging member 48 </ b> A and the exposure device frame 42. The compression spring 49 is arranged on the inner side in the left-right direction (the inner side in the longitudinal direction of the exposure member) than the two guide rollers 44. When the engaging member 48A, the opening 42E of the exposure device frame 42 and the engagement claw 42F are engaged with play and then locked by a retaining member (not shown), the exposure device frame 42 and the LED head 41 are The compression spring 49 is always urged toward the photosensitive drum 53.

  As shown in FIG. 2, the LED unit 40 is attached to the upper cover 12 via the connection link 14 </ b> A and the LED attachment member 14. The connection link 14 </ b> A can be rotated in a side view of FIG. 2 at a connection portion with the LED mounting member 14 and a connection portion with each LED unit 40, thereby freely changing the posture of the LED unit 40. it can. Therefore, it is easy to engage the LED unit 40 with the side frame 15A.

  Each LED unit 40 extends downward from the upper cover 12 when attached to the upper cover 12. As described above, the upper cover 12 can be rotated and opened around the rear hinge 12A, so that the photosensitive drum 53 and the LED unit 40 are located at an exposure position close to each other and a retracted position apart from each other. Relative movement is possible. In the LED unit 40, the guide roller 44 provided at the lower end is in contact with the vicinity of the upper end of the peripheral surface 53 </ b> A of the photosensitive drum 53 at the exposure position, whereby the distance between the peripheral surface 53 </ b> A and the LED head 41 is constant. It is supposed to be kept.

  As shown in FIG. 4, the side frame 15 </ b> A has a front guide 161 and a rear guide 162 corresponding to both ends of the LED unit 40 where the four LED units 40 are mounted. The front guide 161 is disposed in front of the sub-direction positioning surface 45E, and the rear guide 162 is disposed behind the sub-direction positioning surface 45E.

  The front guide 161 is formed with a rib 161A extending substantially in the vertical direction so as to protrude inward in the horizontal direction. The rib 161A is positioned on the front side of the guide rib 45A when the LED unit 40 is mounted. The upper and lower ends of the rib 161A are cylindrical portions 161C that are thicker in the longitudinal direction than the central portion. The cylindrical portion 161C is in contact with the sub-direction positioning surface 45E and serves as a portion for positioning the LED unit 40 in the sub-direction. Further, an abutting portion 161B as an example of a reference portion is provided on the rear edge of the front guide 161 along the rib 161A. The abutting portion 161B is a surface on which the main direction positioning surface 45D of the LED unit 40 can come into contact, and the right abutting portion 161B abuts on one end side of the LED unit 40 to regulate the position of the LED unit 40 in the left-right direction. (See FIG. 5). The abutting portion 161B and the main direction positioning surface 45D are each formed with a predetermined smoothness so as to be slidable with each other. The abutting portion 161B and the main direction positioning surface 45D may be surface contact or point contact.

  The rear guide 162 is provided with an arm 162A extending from the bottom to the top. The arm 162A is supported by the metal plate of the side frame 15A so as to be rotatable about the rotation shaft 162B. A torsion spring 162C is provided around the rotation shaft 162B, and an urging force is always applied to the arm 162A counterclockwise in FIG. 4 by the torsion spring 162C.

  Both the front guide 161 and the rear guide 162 are made of resin, and thereby wear due to sliding contact with the LED unit 40 is suppressed.

As shown in FIG. 5, the right side frame 15A includes a first vertical wall A1 to which the front guide 161 is fixed, a horizontal wall A2 bent rightward from the upper end of the first vertical wall A1, and a horizontal wall A.
2 and a second vertical wall A3 bent upward from the right end. A through hole 15 </ b> C for engaging the second wall 102 of the leaf spring 100 with the side frame 15 </ b> A in the vicinity of the abutting portion 161 </ b> B of the front guide 161 is formed in the lateral wall A <b> 2. Therefore, when the second wall 102 of the leaf spring 100 is inserted into the through hole 15C and engaged with the first vertical wall A1 of the side frame 15A, the second wall 102 of the leaf spring 100 connects the side frame 15A to the LED unit 40. The right end portion (main direction positioning surface 45D) of the LED unit 40 is attracted to and abuts against the abutting portion 161B of the front guide 161. That is, the second wall 102 of the leaf spring 100 sandwiches the side frame 15 </ b> A and the abutting portion 161 </ b> B of the front guide 161 from the right end portion of the LED unit 40 to the left and right. At this time, a predetermined gap is formed between the left end portion of the LED unit 40 and the abutting portion 161B of the front guide 161 of the left side frame 15A.

  The left side frame 15A includes a vertical wall A4 to which the front guide 161 is fixed, and a pedestal wall A5 bent rightward from the lower end of the vertical wall A4. A coil spring 200 as an example of a second urging member that urges the LED unit 40 in a direction away from the photosensitive drum 53 is provided between the pedestal wall A5 and the exposure unit frame 42 of the LED unit 40. It has been. The coil spring 200 is formed of a conductive member such as metal. Each side frame 15A is electrically grounded. The lower end of the coil spring 200 is fixed to the pedestal portion A5.

The operation and effect of the color printer 1 configured as described above will be described.
As shown in FIG. 1, when the process cartridge 50 of the color printer 1 is replaced or maintained, the upper cover 12 is first rotated upward to open, and the LED unit 40 is moved from the exposure position to the retracted position.

  In the color printer 1 of the present embodiment, since the LED unit 40 can move between the exposure position and the retracted position with respect to the photosensitive drum 53 as described above, it is necessary to position the LED unit 40 with respect to the photosensitive drum 53. is there.

  When the maintenance is completed, the upper cover 12 is lowered and closed. At this time, the guide roller 44 at the tip (lower end) of the LED unit 40 contacts the circumferential surface 53A of the photosensitive drum 53 as shown in FIG. Thereby, the distance between the circumferential surface 53A and the light emitting part of the LED head 41 is kept constant.

  At this time, as shown in FIG. 4, the guide rib 45 </ b> A is inserted between the rib 161 </ b> A of the front guide 161 and the arm 162 </ b> A of the rear guide 162. Since the arm 162A is biased forward by the torsion spring 162C, the guide rib 45A is biased forward. Thereby, the sub-direction positioning surface 45E of the guide rib 45A comes into contact with the cylindrical portions 161C at both ends of the rib 161A, and the LED unit 40 is positioned in the sub-direction.

  Further, at this time, as shown in FIG. 5, the second wall 102 of the leaf spring 100 provided in the LED unit 40 passes through the through hole 15C of the right side frame 15A, and its tip is bent to the right. Engage with the outer surface of the first vertical wall A1. As a result, the urging force of the second wall 102 of the leaf spring 100 causes the right main-direction positioning surface 45D of the LED unit 40 to be pulled to the right and contact the abutting portion 161B of the front guide 161, so that the LED unit 40 is Positioned in the direction.

  In the positioning in the main direction as described above, the exposure unit frame 42 is electrically grounded via the leaf spring 100 and the side frame 15A, and electrically grounded via the coil spring 200 and the side frame 15A. Is done.

According to the above, the following effects can be obtained in the present embodiment.
The leaf spring 100 urges the right main direction positioning surface 45D of the LED unit 40 so as to be attracted to the abutting portion 161B of the front guide 161 provided on the right side frame 15A. On the other hand, the LED unit 40 can be positioned in the main direction. Further, since the leaf spring 100 is provided only on one end side of the LED unit 40, for example, one coil spring having a different urging force is provided on each end side of the LED unit, and the LED unit is side-mounted by the coil spring having the larger urging force. The distortion of the side frame can be suppressed compared to the structure that presses against the frame.

  By using the leaf spring 100 having elasticity as a pressing member that presses the LED unit 40 against the abutting portion 161B of the side frame 15A, positioning can be performed with a simple structure, so that the cost can be reduced.

  Since the abutting portion 161B of the front guide 161 and the main direction positioning surface 45D of the LED unit 40 are slidable, the photosensitive drum 53 is formed in a somewhat elliptical shape within a range of manufacturing errors. In addition, the LED unit 40 can be smoothly moved in the vertical direction, and the guide roller 44 can be reliably kept in contact with the peripheral surface 53A of the photosensitive drum 53. Therefore, the distance between the LED head 41 and the photosensitive drum 53 can be reliably maintained constant.

  Since the exposure unit frame 42 is electrically grounded via the leaf spring 100, the coil spring 200, and the side frame 15A, even when using the LED head 41 whose exterior is formed of resin as in this embodiment, It can be grounded via a metal exposure device frame 42 that is in close contact with the upper surface of the LED head 41. Thereby, the electric charge generated on the surface of the LED head 41 can be sufficiently removed. Even if a large current flows through the LED head 41 and electromagnetic waves are generated, the exposure device frame 42 is formed larger in the left-right direction than the LED head 41, and a metal side frame is provided on both sides of the LED head 41 in the left-right direction. Since 15A is provided, electromagnetic waves are sufficiently absorbed by these members, and the influence of electromagnetic waves on other devices can be suppressed. In particular, in the present embodiment, the above-described configuration is adopted on both the left and right sides, so that grounding and electromagnetic wave absorption can be sufficiently performed. In this embodiment, since the leaf spring 100 is used for positioning in the main direction, the positioning of the LED head 41, the grounding of the LED head 41, and the shielding of electromagnetic waves can be performed simultaneously. Furthermore, by making the LED head 41 a resin exterior, the LED head 41 can be downsized, the degree of freedom in layout around the photosensitive drum 53 is increased, and the color printer 1 can be downsized.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the said embodiment, although the leaf | plate spring 100 as a press member was provided in the LED unit 40, this invention is not limited to this. For example, as shown in FIGS. 6 and 7, a leaf spring 110 may be provided on the right side frame 15A. In FIG. 6 and FIG. 7, the same reference numerals are given to the same components as those in the above embodiment, and the description thereof is omitted. Although illustration of the left side frame 15A is omitted, the leaf spring 110 is not provided on the left side frame 15A, as in the embodiment (FIG. 5), and the left side frame 15A A gap is formed between the LED unit 400.

Specifically, the leaf spring 110 shown in FIG. 6 has a structure in which the leaf spring 100 according to the embodiment is turned upside down, and the first wall 111 and the second wall 112 that are substantially the same as those in the embodiment. In addition to the front end portion 113, a fixing portion 114 for fixing the first wall 111 to the side frame 15A is provided. When the leaf spring 110 is fixed to the inner surface of the side frame 15A, the front end portion 113 of the leaf spring 110 is disposed on the inner side in the left-right direction of the abutting portion 161B of the front guide 161 fixed to the side frame 15A. It has become.

  In this structure, the LED unit 400 has a resin cover 450 different from the LED unit 40 according to the embodiment. Specifically, the resin cover 450 is formed with a recess 451 opening downward on the lower surface thereof, thereby forming a protruding wall 452 protruding downward on the outer side in the left-right direction of the resin cover 450.

  The protruding wall 452 is sandwiched between the abutting portion 161B of the front guide 161 and the distal end portion 113 of the leaf spring 110 at the exposure position, so that the outer surface thereof comes into contact with the abutting portion 161B. Yes. Thereby, the LED unit 400 can be positioned in the main direction.

  Further, as shown in FIG. 7, the leaf spring 110 may be fixed to the outer surface of the side frame 15A. In this case, the protruding wall 452 of the resin cover 450 described above is sandwiched between the front end portion 113 of the leaf spring 110 and the outer surface of the side frame 15A, whereby the protruding wall 452 is urged by the leaf spring 110 and the side frame 15A. Abuts against the outer surface of That is, in this embodiment, the reference portion is the outer surface of the side frame 15A. Thereby, the LED unit 400 can be positioned in the main direction.

  In the embodiment, the leaf spring 100 is used as the pressing member, but the present invention is not limited to this, and may be a torsion spring, for example. Moreover, you may employ | adopt a disc spring, a leaf | plate spring, etc. as a 1st biasing member or a 2nd biasing member.

  In the said embodiment, although the leaf | plate spring 100 which has elasticity (flexibility) as a press member was employ | adopted, this invention is not limited to this.

  In the said embodiment, although the form which has two or more LED was illustrated as a several light emission part, in order to form this several light emission part, one light emitting element like LED may be sufficient. For example, one backlight such as a fluorescent lamp may be prepared, and an optical shutter of liquid crystal or PLZT elements arranged in a line in the left-right direction may be provided outside the backlight. That is, a plurality of light emitting units arranged in a row can be formed by combining one light emitting element and a row of optical shutters. In addition, the light emitting units may be arranged in a plurality of rows instead of being arranged in a row in the left-right direction. Furthermore, the light emitting element is not limited to an LED, and may be an EL (electroluminescence) element or a phosphor.

  The side frames 15 </ b> A (main body frames 15) arranged on both sides of the photosensitive drum 53 may be the framework of the color printer 1, or a drawer frame in which a plurality of process cartridges 50 are collectively attached to and detached from the color printer 1. It doesn't matter.

In the above embodiment, the present invention is applied to the color printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine.
In the above-described embodiment, the photosensitive drum 53 is employed as the photosensitive member. However, the present invention is not limited to this, and for example, a belt-shaped photosensitive member may be employed.

1 is a cross-sectional view illustrating an overall configuration of a color printer as an example of an image forming apparatus. It is an enlarged view of the LED unit and process cartridge of FIG. (A) is an exploded perspective view of an LED unit, and (b) is an enlarged perspective view of a guide roller. It is a side view which shows the positional relationship of an LED unit and a side plate. It is the figure which looked at the photosensitive drum and LED unit from back. It is a figure which shows the modification which provided the leaf | plate spring in the inner surface of the side frame. It is a figure which shows the modification which provided the leaf | plate spring in the outer surface of the side frame.

DESCRIPTION OF SYMBOLS 1 Color printer 15 Main body frame 15A Side frame 40 LED unit 41 LED head 42 Exposure device frame 45 Resin cover 45D Main direction positioning surface 49 Compression spring 53 Photosensitive drum 101 1st wall 102 2nd wall 103 Tip part 161 Front guide 161B Abutting Part

Claims (9)

A photosensitive drum, an exposure member that is disposed to face the photosensitive drum and has a plurality of light emitting portions arranged in the longitudinal direction to expose the photosensitive drum, and a main body frame that is disposed on both sides in the longitudinal direction of the exposure member. An image forming apparatus,
The main body frame is provided with a reference portion for positioning in the longitudinal direction of the exposure member in contact with one end portion in the longitudinal direction of the exposure member,
The main body frame or the exposure member has a pressing member that is arranged on one end side in the longitudinal direction and presses the exposure member in the longitudinal direction so as to draw the one end portion in the longitudinal direction toward the reference portion. An image forming apparatus provided with the image forming apparatus. The said pressing member is provided in the one end part of the said exposure member, It is comprised so that the said reference | standard part may be pinched | interposed between the one end parts in the said longitudinal direction of the said exposure member. Image forming apparatus. The image forming apparatus according to claim 1, wherein the pressing member is provided on the main body frame, and is configured to sandwich one end portion in the longitudinal direction of the exposure member between the reference portion and the reference member. apparatus.   The image forming apparatus according to claim 2, wherein the pressing member has elasticity. The exposure member is configured to be movable between an exposure position and a retracted position,
The pressing member is configured to press one end portion in the longitudinal direction of the exposure member against the reference portion by moving toward the reference portion as the exposure member moves to the exposure position. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus. A gap is formed between the other end portion of the exposure member in the longitudinal direction and the main body frame in a state where the one end portion in the longitudinal direction of the exposure member is in contact with the reference portion. The image forming apparatus according to any one of claims 1 to 5. A first urging member that urges the exposure member toward the photosensitive drum;
2. The exposure member includes an abutting portion that abuts on the photosensitive drum by the urging of the first urging member, and is configured to be slidable with respect to the reference portion. The image forming apparatus according to claim 6. The main body frame and the pressing member have conductivity,
The said exposure member is provided with the exposure member main body which has the said light emission part, and the electroconductive holding member which contacts the said press member while supporting the said exposure member main body. 8. The image forming apparatus according to any one of 7 above.   A conductive second urging member that urges the exposure member in a direction away from the photosensitive drum between the main body frame and a portion of the holding member that is opposite to the pressing member in the longitudinal direction. The image forming apparatus according to claim 1, wherein a member is provided.