CN213023949U - Exposure device for image forming apparatus and image forming apparatus - Google Patents

Abstract

The utility model provides an image forming apparatus's exposure device and image forming apparatus. An exposure device of an image forming apparatus according to an embodiment includes: the image forming apparatus includes a printing head that exposes a photosensitive body and forms a latent image on the photosensitive body, a lifting mechanism that lifts the printing head, and a biasing member that biases the printing head toward the photosensitive body. The elevating mechanism positions the print head with respect to the photoreceptor by bringing the print head into contact with a photoreceptor support body that supports the photoreceptor. The urging member is disposed at a position aligned with a contact portion between the print head and the photosensitive body support in a lifting direction of the print head. The mounting portion of the print head and the lifting mechanism is located near the abutting portion. Through the utility model discloses, can prevent to beat printer head and take place the warpage when beating printer head and passing through elevating system decline.

Description

Exposure device for image forming apparatus and image forming apparatus

Technical Field

The present invention relates to an exposure device of an image forming apparatus and an image forming apparatus.

Background

An image forming apparatus such as an electrophotographic apparatus has an exposure apparatus using a print head, for example. In such an exposure apparatus, it is necessary to position the print head and the photosensitive drum. As such a positioning technique, the following method is known. The print head can be brought into contact with a support body supporting the photosensitive drum by using a lifting mechanism for lifting the print head. Further, a predetermined contact load is applied to the print head by a biasing member such as a coil spring.

However, when the print head is lowered by the lifting mechanism against the urging force of the coil spring, the print head may warp due to the inability to suppress the urging force of the coil spring.

SUMMERY OF THE UTILITY MODEL

The utility model provides a prevent to beat printer head when beating printer head and descend through elevating system and take place warped image forming device's exposure device and image forming device.

An exposure device of an image forming apparatus according to an embodiment includes: a print head that exposes a photoconductor and forms a latent image on the photoconductor; a lifting mechanism for lifting the print head so that the print head is positioned with respect to the photoconductor by abutting the print head against a photoconductor support body that supports the photoconductor, and the mounting portion of the print head is located in the vicinity of an abutting portion between the print head and the photoconductor support body; and a biasing member that is disposed at a position aligned with the abutment portion in a lifting direction of the print head, and biases the print head toward the photoreceptor.

An image forming apparatus according to another embodiment includes: a photoreceptor; a photoreceptor support body that supports the photoreceptor; a cleaner that cleans the photoreceptor; a charging charger that charges the photoreceptor; an exposure device; a developing device which develops the latent image formed on the photosensitive body to form an image; a transfer belt on which the image formed on the photoreceptor is transferred; and a transfer roller pair that transfers the image transferred onto the transfer belt onto a sheet, wherein the exposure apparatus has: a print head that exposes the photoconductor and forms a latent image on the photoconductor; a lifting mechanism for lifting the print head so that the print head is positioned with respect to the photoconductor by abutting the print head against the photoconductor support, and a mounting portion of the print head is located in the vicinity of an abutting portion between the print head and the photoconductor support; and a biasing member that is disposed at a position aligned with the abutment portion in a lifting direction of the print head, and biases the print head toward the photoreceptor.

Through the utility model discloses, can prevent to beat printer head and take place the warpage when beating printer head and passing through elevating system decline.

Drawings

Fig. 1 is a diagram illustrating an image forming apparatus according to an embodiment;

FIG. 2 is a perspective view showing the basic structure of the photosensitive drum and the exposure device shown in FIG. 1;

FIG. 3 is a diagram showing an example of the print head shown in FIG. 2;

FIG. 4 is a diagram showing a light emitting element array on a transparent substrate of the print head shown in FIG. 3;

FIG. 5 is a side view showing the entire photoreceptor unit and exposure device;

FIG. 6 is an enlarged side view showing a part of the rear side of the photosensitive body unit and the exposure device shown in FIG. 5;

FIG. 7 is an enlarged side view showing a part of the near side of the photosensitive body unit and the exposure device shown in FIG. 5;

fig. 8 is a side view showing the entire exposure apparatus shown in fig. 5, fig. 8(a) showing the exposure apparatus in which the print head is in an ascending state, and fig. 8(b) showing the exposure apparatus in which the print head is in a descending state;

fig. 9 is a perspective view of the exposure apparatus in which the elevating mechanism shown in fig. 8 is exploded;

fig. 10 is another perspective view of the exposure apparatus in which the elevating mechanism shown in fig. 8 is exploded;

fig. 11 is a side view of the elevating unit of the elevating mechanism shown in fig. 9 and 10, as viewed from the outside;

fig. 12 is a side view of the elevating unit of the elevating mechanism shown in fig. 9 and 10, as viewed from the inside;

fig. 13 is a side view of the slider portion of the lifting mechanism shown in fig. 9 and 10, as viewed from the inside.

Detailed Description

The exposure apparatus of the embodiment includes: the image forming apparatus includes a printing head that exposes a photosensitive body and forms a latent image on the photosensitive body, a lifting mechanism that lifts the printing head, and a biasing member that biases the printing head toward the photosensitive body. The elevating mechanism positions the print head with respect to the photoreceptor by bringing the print head into contact with a photoreceptor support body that supports the photoreceptor. The urging member is disposed at a position aligned with a contact portion between the print head and the photosensitive body support in a lifting direction of the print head. The mounting portion of the print head and the lifting mechanism is located near the abutting portion.

An image forming apparatus according to an embodiment includes: the image forming apparatus includes a photoreceptor, a photoreceptor support for supporting the photoreceptor, a cleaner for cleaning the photoreceptor, a charging charger for charging the photoreceptor, and an exposure device for exposing the photoreceptor. The exposure device comprises: the image forming apparatus includes a photosensitive body, a print head that exposes the photosensitive body and forms a latent image on the photosensitive body, a lifting mechanism that lifts and lowers the print head for positioning the print head relative to the photosensitive body by bringing the print head into contact with the photosensitive body support, and a biasing member that biases the print head toward the photosensitive body. The urging member is disposed at a position aligned with the abutment portion in a lifting direction of the print head. The mounting portion of the print head and the elevating mechanism is located in the vicinity of the contact portion between the print head and the photoreceptor support body. The image forming apparatus further includes: a developing device that develops the latent image formed on the photosensitive body to form an image, a transfer belt on which the image formed on the photosensitive body is transferred, and a transfer roller pair that transfers the image transferred on the transfer belt to a sheet of paper.

Fig. 1 shows an image forming apparatus 100 according to an embodiment. The image forming apparatus 100 is a four-in-one tandem type color image forming apparatus. The image forming apparatus 100 is an image forming apparatus such as a printer, a copier, or a multifunction peripheral.

The image forming apparatus 100 has an image forming unit 102-Y that forms a yellow (Y) image, an image forming unit 102-M that forms a magenta (M) image, an image forming unit 102-C that forms a cyan (C) image, and an image forming unit 102-K that forms a black (K) image. The image forming units 102-Y, 102-M, 102-C, 102-K form yellow, cyan, magenta, and black images, respectively, and transfer the images onto the transfer belt 103. Thereby, a full color image is formed on the transfer belt 103.

The image forming unit 102-Y has a charging charger 112-Y, an exposure device 113-Y, a developer 114-Y, a transfer roller 115-Y, and a cleaner 116-Y around the photosensitive drum 111-Y. The image forming units 102-M, 102-C, and 102-K have the same structure.

In FIG. 1, the structure of the image forming unit 102-Y for forming a yellow (Y) image is denoted by "-Y". The structure of the image forming unit 102-M that forms a magenta (M) image is denoted by a symbol "-M". For the structure of the image forming unit 102-C forming a cyan (C) image, the symbol "-C" is given. For the structure of the image forming unit 102-K forming a black (K) image, the symbol "-K" is noted.

The charging chargers 112-Y, 112-M, 112-C, and 112-K uniformly charge the photosensitive drums 111-Y, 111-M, 111-C, and 111-K, respectively. Exposure devices 113-Y, 113-M, 113-C, 113-K expose the photosensitive drums 111-Y, 111-M, 111-C, 111-K, respectively, to form electrostatic latent images on the photosensitive drums 111-Y, 111-M, 111-C, 111-K. The developers 114-Y, 114-M, 114-C, 114-K respectively attach yellow toner, magenta toner, cyan toner, black toner to the electrostatic latent image portions of the photosensitive drums 111-Y, 111-M, 111-C, 111-K to form toner images (develop electrostatic latent images).

The transfer rollers 115-Y, 115-M, 115-C, 115-K transfer the toner images formed on the photosensitive drums 111-Y, 111-M, 111-C, 111-K to the transfer belt 103, respectively. Cleaners 116-Y, 116-M, 116-C, 116-K clean untransferred toner remaining on the photosensitive drums 111-Y, 111-M, 111-C, 111-K, respectively. Thus, the photosensitive drums 111-Y, 111-M, 111-C, 111-K are in a standby state for the next image formation.

The first size (small size) sheet 121-1 is housed in the sheet cassette 117-1. The second-size (large-size) sheet 121-2 is housed in the paper cassette 117-2.

The toner image is transferred from the transfer belt 103 onto the sheet 121-1 or 121-2 taken out of the sheet cassette 117-1 or 117-2 by the transfer roller pair 118. The sheet 121-1 or 121-2 on which the toner image is transferred is heated and pressurized by a fixing roller 120 of the fixing portion 119. The toner image is firmly fixed on the paper 121-1 or 121-2 by the heat and pressure of the fixing roller 120. By repeating the above-described processing operation, the image forming operation is continuously executed.

The photosensitive drums 111-Y, 111-M, 111-C, and 111-K and the exposure devices 113-Y, 113-M, 113-C, and 113-K shown in FIG. 1 will be described below. The image forming units 102-Y, 102-M, 102-C, 102-K have substantially the same structure except for the difference in toner color. Therefore, in the following description, the exposure devices 113-Y, 113-M, 113-C, 113-K are not distinguished, but the exposure device 113 is represented, and the photosensitive drums 111-Y, 111-M, 111-C, 111-K are not distinguished, but the photosensitive drum 111 is represented.

Fig. 2 is a perspective view showing a basic structure of the photosensitive drum 111 and the exposure device 113 shown in fig. 1.

The exposure device 113 has a print head 1 that exposes a photosensitive drum (photosensitive body) 111 to form a latent image on the photosensitive drum 111. The print head 1 is disposed to face the photosensitive drum 111.

The photosensitive drum 111 rotates in the direction of the arrow shown in fig. 2. Hereinafter, the rotation direction of the photosensitive drum 111 is referred to as a sub-scanning direction SD. A direction perpendicular to the rotation direction of the photosensitive drum 111, i.e., a direction parallel to the rotation axis of the photosensitive drum 111 is referred to as a longitudinal direction or a main scanning direction MD.

The photosensitive drum 111 is uniformly charged by the charger and exposed by light from the print head 1 of the exposure device 113, so that the potential of the exposed portion drops. That is, by controlling the emission and non-emission of light by the print head 1, an electrostatic latent image is formed on the photosensitive drum 111.

The print head 1 has a light emitting portion 10. The light emitting section 10 has a transparent substrate 11. The transparent substrate 11 is, for example, a glass substrate that transmits light. The transparent substrate 11 is formed with high surface precision. A single or a plurality of light emitting element columns 13L are provided on the transparent substrate 11. Each light emitting element row 13L has a plurality of light emitting elements. Each light emitting element row 13L is arranged parallel to the rotation axis of the photosensitive drum 111. The light emitting element is formed of, for example, an LED. Alternatively, the light-emitting element may be constituted of, for example, organic el (oled).

The print head 1 also has a rod lens array 12. The rod lens array 12 is disposed between the light emitting section 10 and the photosensitive drum 111. Specifically, the rod lens array 12 is disposed between the light emitting element row 13L and the photosensitive drum 111. The rod lens array 12 is arranged parallel to the rotation axis of the photosensitive drum 111. The rod lens array 12 concentrates light emitted from the light emitting element row 13L of the light emitting section 10 on the photosensitive drum 111.

The printhead 1 has, for example, two light emitting element rows 13L (a first light emitting element row 13L1 and a second light emitting element row 13L 2). In the present embodiment, an example in which the print head 1 has two light emitting element arrays 13L will be described, but the present invention is not limited thereto. For example, the print head 1 may have a structure having one light emitting element column 13L.

Fig. 3 is a view showing an example of a transparent substrate constituting the print head shown in fig. 2. As shown in fig. 3, two light-emitting element rows 13L (a first light-emitting element row 13L1 and a second light-emitting element row 13L2) are provided in the central portion of the transparent substrate 11 along the longitudinal direction of the transparent substrate 11. In the vicinity of the light emitting element row 13L (the first light emitting element row 13L1 and the second light emitting element row 13L2), a drive circuit row 14L (the first drive circuit row 14L1 and the second drive circuit row 14L2) for driving each light emitting element (light emission) is formed.

As shown in fig. 3, the driving circuit columns 14L are disposed on both sides of the two light emitting element columns 13L, for example. Further, the driving circuit column 14L may be arranged on one side of the two light emitting element columns 13L. The light emitting element row 13L and the drive circuit row 14L are covered with a transparent cover 17 so as not to be in contact with the outside air.

An IC (Integrated Circuit) 15 is disposed at an end portion of the transparent substrate 11. The transparent substrate 11 also has a connector 16. The connector 16 is electrically connected to the print head 1 and a control system of the image forming apparatus. By this connection, power supply, head control, image data transmission, and the like can be performed. In the case where it is difficult to mount the connector 16 on the transparent substrate 11, an FPC (Flexible Printed Circuits) may be connected to the transparent substrate 11, and electrical connection with the control system may be achieved via the FPC.

Fig. 4 is a diagram showing an example of the light emitting element row (two row heads) shown in fig. 3. As shown in fig. 4, each light-emitting element row 13L has a plurality of light-emitting elements 13 arranged in the main scanning direction MD. That is, the arrangement direction of the plurality of light emitting elements 13 forming the first light emitting element row 13L1 and the arrangement direction of the plurality of light emitting elements 13 forming the second light emitting element row 13L2 are parallel to the main scanning direction MD.

The light emitting element 13 has a square size of 20 μm, for example. The light emitting elements 13 of the first light emitting element row 13L1 and the light emitting elements 13 of the second light emitting element row 13L2 are arranged at a predetermined arrangement interval D11 along the main scanning direction MD. The arrangement interval D11 of the light emitting elements 13 is, for example, about 42.3 μm so that the resolution is 600 dpi.

The first light-emitting element row 13L1 and the second light-emitting element row 13L2 are arranged at a distance D12 in the sub-scanning direction SD. The light emitting elements 13 forming the first light emitting element row 13L1 and the light emitting elements 13 forming the second light emitting element row 13L2 are arranged with a predetermined pitch D13 shifted from each other in the main scanning direction MD. For example, the predetermined pitch D13 is 1/2 at the arrangement interval D11. Thereby, the two light emitting element rows 13L are arranged alternately.

When the light emitting elements of the first light emitting element row 13L1 emit light at the same timing as the light emitting elements of the second light emitting element row 13L2, an interleaved exposure pattern is formed on the photosensitive drum 111. Here, for convenience of explanation, the light-emitting element row 13L located on the upstream side with respect to the moving direction of the photosensitive drum 111 is referred to as a first light-emitting element row 13L1, and the light-emitting element row 13L located on the downstream side is referred to as a second light-emitting element row 13L 2. The controller that controls the image forming operation causes the first light-emitting element row 13L1 and the second light-emitting element row 13L2 to emit light at different timings according to the moving speed of the photosensitive drum 111 and the distance D12. That is, the control section delays the light emission timing of the second light emitting element row 13L2 with respect to the first light emitting element row 13L1 by a certain time period in accordance with the moving speed of the photosensitive drum 111 and the distance D12. In other words, the control section outputs the first light-emitting element image data to the first light-emitting element array 13L1 and the second light-emitting element image data to the second light-emitting element array 13L2 at different timings according to the moving speed of the photosensitive drum 111 and the distance D12. Here, the first light emitting element image data and the second light emitting element image data correspond to image data of one line in the main scanning direction. Thereby, a latent image was formed on the photosensitive drum at a resolution of 1200 dpi.

Thus, the control unit controls the light emission timing (image data transfer timing) of the plurality of light emitting element rows 13L, thereby realizing image densification. In the case of two light emitting element rows 13L, the density of an image can be made as high as twice the density of the light emitting elements 13 per row, and in the case of n (n.gtoreq.3, n: an integer) light emitting element rows 13L, the density of an image can be made as high as n times the density of the light emitting elements 13 per row.

Hereinafter, a specific configuration of the exposure apparatus 113 will be described with reference to fig. 5 to 13.

Fig. 5 is a side view showing the overall configuration of the photosensitive unit 130 having the photosensitive drum 111 and the exposure device 113. In fig. 5, the left side corresponds to the rear side of the image forming apparatus 100, and the right side corresponds to the front side of the image forming apparatus 100. Fig. 6 is an enlarged side view of a part of the rear side of the photosensitive body unit 130 and the exposure device 113 shown in fig. 5. Fig. 7 is an enlarged side view of a portion of the photosensitive body unit 130 and the exposure device 113 shown in fig. 5 on the near side.

Fig. 8 is a side view showing the entire exposure apparatus 113 shown in fig. 5. In fig. 8, fig. 8(a) shows the exposure device 113 with the print head 1 in the raised state, and fig. 8(b) shows the exposure device 113 with the print head 1 in the lowered state.

Fig. 9 and 10 are perspective views of the exposure apparatus 113 shown in fig. 8 with the elevating mechanism 30 exploded. Fig. 9 is depicted so that the inside of the lifting portion 40 of the lifting mechanism 30 can be seen, and fig. 10 is depicted so that the inside of the slider portion 50 of the lifting mechanism 30 can be seen. Here, the inner sides of the elevating portion 40 and the slider portion 50 refer to the sides of the elevating portion 40 and the slider portion 50 facing each other.

Fig. 11 is a side view of the elevating unit 40 of the elevating mechanism 30 shown in fig. 9 and 10, as viewed from the outside. Fig. 12 is a side view of the elevating unit 40 of the elevating mechanism 30 shown in fig. 9 and 10, as viewed from the inside. Fig. 13 is a side view of the slider portion 50 of the lifting mechanism 30 shown in fig. 9 and 10, as viewed from the inside.

The exposure device 113 has the print head 1 shown in fig. 2. The exposure device 113 is disposed inside the image forming apparatus 100 such that the longitudinal direction of the print head 1 extends in the front-rear direction of the image forming apparatus 100.

The photosensitive drum 111 is accommodated in the photosensitive body unit 130. The photosensitive body unit 130 has a housing 131. The housing 131 rotatably holds the photosensitive drum 111. That is, the housing 131 is a photosensitive body support body that supports the photosensitive drum 111.

The photosensitive body unit 130 is mounted in the image forming apparatus 100 in a replaceable manner. For example, the photosensitive body unit 130 is mounted in the image forming apparatus 100 and dismounted from the image forming apparatus 100 by being inserted and removed from the near side of the image forming apparatus 100. The photosensitive drum unit 130 is installed in the image forming apparatus 100 in such a manner that the photosensitive drum 111 is parallel to the print head 1 of the exposure device 113.

As described with reference to fig. 2, the print head 1 includes the light emitting portion 10 and the rod lens array 12, and further includes a holder 20 for holding the light emitting portion 10 and the rod lens array 12. The holder 20 has a slit extending in the longitudinal direction, and the rod lens array 12 is housed and fixed in the slit.

The exposure device 113 further includes an elevating mechanism 30 for elevating the print head 1. The lift mechanism 30 has a function of raising the print head 1 and a function of lowering the print head 1. Here, raising the print head 1 means bringing the print head 1 close to the photosensitive drum 111, and lowering the print head 1 means separating the print head 1 from the photosensitive drum 111.

Here, the photosensitive drum 111 naturally refers to a photosensitive drum housed in the photosensitive body unit 130 attached to the image forming apparatus 100. In the following description, the photosensitive drum 111 refers to a photosensitive drum mounted in the photosensitive body unit 130 of the image forming apparatus 100.

The elevating mechanism 30 includes an elevating portion 40 that can be elevated and lowered for holding the print head 1, and a slider portion 50 that can move in the longitudinal direction.

The carriage 20 of the print head 1 is attached to the elevating portion 40 via a plurality of, for example, four attaching portions 42. Thereby, the print head 1 is held by the elevating portion 40 of the elevating mechanism 30.

The elevating unit 40 and the slider unit 50 are connected to each other so as to be movable relative to each other. The connection between the elevating portion 40 and the slider portion 50 will be described later.

The elevating mechanism 30 further has a guide 60 that guides the slider portion 50 in the longitudinal direction. The guide 60 has a function of restricting the movement of the slider portion 50 in the longitudinal direction.

The elevating mechanism 30 also has a pair of elevating guides 70 that guide the print head 1 in the elevating direction. Here, the lifting direction is a direction approaching or separating from the photosensitive drum 111. A pair of elevating guides 70 is provided at positions corresponding to both end portions of the print head 1. The lifting guide 70 has a function of restricting the movement of the print head 1 in the lifting direction.

As shown in fig. 9 and 12, the lifting unit 40 includes a plurality of, for example, three link arms 41. The plurality of link arms 41 have substantially the same structure. The link arm 41 is provided at a lower portion of the elevating portion 40. Here, the upper and lower sides of the elevating unit 40 correspond to the elevating direction of the elevating unit 40. The link arm 41 protrudes inward from the inner surface of the elevating portion 40. For example, the link arm 41 has a shaft portion 41a protruding from the lifting portion 40 and a tip portion 41b thicker than the shaft portion 41 a. For example, the shaft portion 41a and the distal end portion 41b each have a cylindrical shape.

As shown in fig. 10 and 13, the slider part 50 has a plurality of link grooves 51 that accommodate the plurality of link arms 41, respectively. The number of link grooves 51 is the same as the number of link arms 41. The plurality of link grooves 51 have substantially the same structure. The link groove 51 is formed of, for example, a slit. The link groove 51 extends along the longitudinal direction of the slider portion 50, and also has an inclined portion 51a inclined with respect to the longitudinal direction of the slider portion 50. The inclined portion 51a is inclined upward with respect to the direction from the rear side to the front side, for example.

One end portion 51b of the link groove 51 has a size through which the tip end portion 41b of the link arm 41 passes. The other part of the link groove 51 has a size such that the tip end portion 41b of the link arm 41 does not pass through and the shaft portion 41a of the link arm 41 passes through.

The lifting portion 40 and the slider portion 50 are connected to each other by passing the tip end portion 41b of the link arm 41 through the end portion 51b of the link groove 51. The link arm 41 is movable along the link groove 51. Therefore, the elevating unit 40 and the slider unit 50 are connected to be movable relative to each other. In a state where the link arm 41 is detached from the end 51b of the link groove 51, the lifting and lowering portion 40 is prevented from being disconnected from the slider portion 50.

Since the movement direction of the elevating unit 40 is restricted to the elevating direction by the elevating guide 70, the elevating unit 40 does not move in the longitudinal direction together with the slider unit 50 even if the slider unit 50 moves in the longitudinal direction. Accordingly, the link arm 41 moves along the link groove 51 with respect to the movement of the slider portion 50 in the longitudinal direction. As a result, the lifting part 40 moves in the lifting direction.

For example, when the slider unit 50 is moved to the front side from the state where the lifting unit 40 is lifted as shown in fig. 8(a), the lifting unit 40 is lowered as shown in fig. 8(b) in accordance with the movement of the slider unit 50. In contrast, when the slider unit 50 is moved to the rear side from the state where the ascending and descending unit 40 is lowered as shown in fig. 8(b), the ascending and descending unit 40 ascends as shown in fig. 8(a) in accordance with the movement of the slider unit 50.

As shown in fig. 6 and 7, the housing 131 has two projections 132 projecting toward the print head 1. Further, as shown in fig. 9 and 10, the holder 20 of the print head 1 has two concave portions 21 that receive the two convex portions 132, respectively. The convex portion 132 of the housing 131 and the concave portion 21 of the holder 20 have a function of contacting each other when the print head 1 is raised by the elevating mechanism 30 to relatively position the print head 1 and the photosensitive drum 111. That is, the print head 1 abuts the casing 131 at two locations on both sides of the photosensitive drum 111. The lifting mechanism 30 positions the print head 1 with respect to the photosensitive drum 111 by bringing the print head 1 into contact with the housing 131 that supports the photosensitive drum 111. Specifically, the convex portion 132 of the housing 131 and the concave portion 21 of the holder 20 have a function of relatively positioning the print head 1 and the photosensitive drum 111 in the longitudinal direction, the lifting direction, and the direction perpendicular to the longitudinal direction and the lifting direction.

The elevating mechanism 30 further has a pair of urging members, such as coil springs 71, that urge the print head 1 toward the photosensitive drum 111. For example, each coil spring 71 is built in each elevation guide 70. In fig. 5 and 6, only one coil spring 71 built in the elevating guide 70 at the rear side is shown. Although not shown in fig. 5 and 7, a coil spring is also built in the lifting guide 70 on the front side. Also, although not shown in fig. 8, one coil spring is built in each of the pair of elevation guides 70.

As shown in fig. 6, each coil spring 71 extends, for example, between the print head 1 and the guide 60. The coil spring 71 urges the print head 1 in a direction away from the guide 60. In a state where the print head 1 is raised by the elevating mechanism 30 and is in contact with the photosensitive body unit 130, the coil spring 71 applies a predetermined contact load to the print head 1.

The coil spring 71 is disposed at a position aligned with an abutment portion between the print head 1 and the housing 131 in the lifting direction of the print head 1. Here, the contact portion between the print head 1 and the housing 131 refers to a contact portion between the convex portion 132 of the housing 131 and the concave portion 21 of the holder 20. The coil spring 71 and the contact portion are aligned in the ascending/descending direction, which means that the center of the coil spring 71 and the center of the contact portion are located on a straight line parallel to the ascending/descending direction.

Thus, since the coil spring 71 is disposed at a position aligned with the contact portion between the print head 1 and the housing 131, when the print head 1 is brought into contact with the housing 131 by the elevating mechanism 30, the coil spring 71 applies an appropriate contact load to the print head 1 without warping the print head 1. Thereby, an appropriate interval is secured between the photosensitive drum 111 and the print head 1. That is, the focal position of the print head 1 is accurately arranged on the surface of the photosensitive drum 111.

Here, although an example in which the biasing member is constituted by the coil spring 71 is shown, the biasing member is not limited to this, and may be constituted by an elastic body such as a leaf spring, rubber, or sponge. Further, although an example in which one urging member is constituted by one coil spring 71 is shown, the present invention is not limited thereto, and one urging member may be constituted by a plurality of coil springs 71 or the like. Further, the configuration in which one urging member is provided at the positions corresponding to both end portions of the print head 1, respectively, is shown, but a configuration in which a plurality of urging members are provided at the positions corresponding to both end portions of the print head 1, respectively, is also possible.

As shown in fig. 5 to 7, of the four mounting portions 42 of the carriage 20 of the print head 1 and the elevating portion 40 of the elevating mechanism 30, two mounting portions 42 closest to both end portions of the print head 1 are located in the vicinity of two contact portions between the casing 131 of the photoconductor unit 130 and the print head 1, respectively. As described above, the contact portion between the housing 131 and the print head 1 is the contact portion between the convex portion 132 of the housing 131 and the concave portion 21 of the holder 20.

Further, the two mounting portions 42 closest to both end portions of the print head 1 are provided at equal distances from the two abutment portions between the housing 131 and the print head 1 in the longitudinal direction of the print head 1. For example, in the longitudinal direction of the print head 1, the distance between the contact portion between the housing 131 and the print head 1 and the mounting portion 42 located in the vicinity thereof is 1/10 or less of the distance between the two contact portions between the housing 131 and the print head 1, and preferably 1/20 or less of the distance between the two contact portions between the housing 131 and the print head 1.

Thus, the print head 1 and the mounting portion 42 of the lifting mechanism 30 close to both end portions of the print head 1 are positioned in the vicinity of the contact portion between the housing 131 and the print head 1. Therefore, when the print head 1 is lowered by the lifting mechanism 30 against the urging force of the coil spring 71, the moment of the force that the print head 1 receives from the coil spring 71 is suppressed to a small value. Thereby, the load applied to the print head 1 is appropriately suppressed. As a result, the occurrence of warpage or the like of the print head 1 due to the urging force of the coil spring 71 can be favorably suppressed.

While several embodiments of the present invention have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various manners, and various omissions, substitutions, combinations, and changes can be made without departing from the gist of the present invention. These embodiments and modifications are included in the scope and gist of the present invention, and are included in the present invention and the equivalent scope thereof described in the claims.

Claims (5)

1. An exposure apparatus of an image forming apparatus, comprising:

a print head that exposes a photoconductor and forms a latent image on the photoconductor;

a lifting mechanism for lifting the print head so that the print head is positioned with respect to the photoconductor by abutting the print head against a photoconductor support body that supports the photoconductor, and the mounting portion of the print head is located in the vicinity of an abutting portion between the print head and the photoconductor support body; and

and a biasing member that is arranged at a position aligned with the abutment portion in a lifting direction of the print head and biases the print head toward the photoreceptor.

2. The exposure apparatus of the image forming apparatus according to claim 1,

two urging members for urging the print head toward the photosensitive body are provided,

the print head and the photoconductor support are abutted at two positions on both sides of the photoconductor,

the two urging members are arranged at positions aligned with two contact portions between the print head and the photosensitive body support body in a lifting direction of the print head,

the print head is mounted to the lifting mechanism by a plurality of mounting portions,

the two mounting portions closest to both end portions of the print head are located in the vicinity of the two abutment portions, respectively, and are equidistant from the two abutment portions in the longitudinal direction of the print head.

3. The exposure apparatus of the image forming apparatus according to claim 2,

in the longitudinal direction of the print head, a distance between the abutment portion and the mounting portion located in the vicinity of the abutment portion is 1/10 or less of a distance between the two abutment portions.

4. The exposure apparatus of the image forming apparatus according to claim 2,

the photoreceptor support has two projections projecting toward the print head,

the print head has two recesses that receive the two projections respectively,

the print head and the photosensitive body are relatively positioned by the convex portion and the concave portion contacting each other,

the abutment portion is a contact portion between the concave portion and the convex portion.

5. An image forming apparatus, comprising:

a photoreceptor;

a photoreceptor support body that supports the photoreceptor;

a cleaner that cleans the photoreceptor;

a charging charger that charges the photoreceptor;

an exposure device;

a developing device which develops the latent image formed on the photosensitive body to form an image;

a transfer belt on which the image formed on the photoreceptor is transferred; and

a transfer roller pair that transfers the image transferred onto the transfer belt onto a sheet, wherein,

the exposure device comprises:

a print head that exposes the photoconductor and forms a latent image on the photoconductor;

a lifting mechanism for lifting the print head so that the print head is positioned with respect to the photoconductor by abutting the print head against the photoconductor support, and a mounting portion of the print head is located in the vicinity of an abutting portion between the print head and the photoconductor support; and

and a biasing member that is arranged at a position aligned with the abutment portion in a lifting direction of the print head and biases the print head toward the photoreceptor.

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