JP4539242B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copier, and a facsimile, and more particularly to an image forming apparatus that records an image using a print head in which a plurality of recording elements are arranged.

  As an image forming apparatus such as a printer, copying machine, facsimile, etc. that employs an electrophotographic system, a photosensitive member having a photosensitive layer and rotatably arranged, and charging for uniformly charging the photosensitive member to a predetermined potential An apparatus, an exposure device that writes an electrostatic latent image on a charged photoreceptor by light irradiation, a developing device that visualizes the electrostatic latent image formed on the photoreceptor by adding toner, and formed on the photoreceptor There is known one provided with a transfer device for transferring the toner image to a recording paper. Here, as an exposure apparatus, an optical scanning method in which a laser is used and exposure is performed by scanning a laser beam in a main scanning direction has been widely used. An exposure apparatus using an LED print head (LPH) in which a large number of emitting diodes (LEDs) are arranged in the main scanning direction is employed.

  In general, LPH is an LED array in which a large number of LEDs are arranged in the main scanning direction, and a self-lock in which a large number of rod lenses are arranged to form an image of light output from the LEDs on the surface of the photosensitive member (photosensitive drum). (Registered trademark) lens. In the image forming apparatus, each LED of the LPH is driven based on input image data, light is output toward the photosensitive member, and light is imaged on the surface of the photosensitive member by the SELFOC lens. An electrostatic latent image is formed in the sub-scanning direction by relatively moving the photoconductor and LPH.

  In order to drive (turn on and turn off) each LED of such an LPH, a driver circuit is required. Therefore, there is a technique in which a driver IC (driver circuit) is integrally provided with the LPH at the end of the LPH in the main scanning direction (see, for example, Patent Document 1).

JP 2000-229440 A (page 9, FIG. 7)

  By the way, the driver IC described above generates heat due to the current flowing through the driver IC when driving the LED. Here, if the amount of heat generated by the driver IC is large, for example, the LPH itself expands or twists due to heat, and the writing position of the electrostatic latent image on the photosensitive member by the LED is shifted. In addition, when the amount of heat generated by the driver IC is large, the light quantity fluctuation of the LED occurs due to the change in the light emission condition of the LED, and the electrostatic latent image formed on the photosensitive member becomes uneven. When such a problem occurs, an image quality defect occurs in an image formed on the recording paper. Furthermore, the photosensitive layer of the photoconductor facing the LPH is also easily deteriorated by heat. Furthermore, in the developing device disposed in the vicinity of the LPH, if the heat generation amount of the driver IC is large, a so-called toner blocking phenomenon in which the toner is melted and fixed by the heat generated in the driver IC occurs, leading to a development failure. .

To solve this problem, the technique described in Patent Document 1 measures the temperature in the vicinity of the driver IC and the temperature of the Selfoc lens, and when the temperature difference between the two exceeds 20 ° C., the image forming operation is stopped. Yes.
However, with such a countermeasure, the image forming operation cannot be performed at all until the temperature difference between the two becomes 20 ° C. or less, which is very inconvenient for the user. Further, since the photoconductor and the developing device are affected by heat to some extent, the photosensitive layer and the toner are still damaged.

The present invention has been made to solve such a technical problem, and an object of the present invention is to occur in a driver circuit when a print head in which a recording element and a driver circuit are integrally formed is used. It is to suppress the transmitted heat from being transmitted to the recording element.
Another object is to suppress the heat generated in the driver circuit from being transmitted to the image carrier and the developing device.

  For this purpose, an image forming apparatus to which the present invention is applied includes an image carrier that is rotatably arranged, and a plurality of images that are disposed along the axial direction of the image carrier so as to face the image carrier. And an exposure unit that integrally exposes the image carrier, and a frame member that holds the exposure unit at one end in the axial direction of the image carrier. A plurality of recording elements and a driver circuit are arranged with a frame member therebetween.

  Here, the driver circuit of the exposure device and the image carrier may be arranged with a frame member therebetween. The image forming apparatus further includes a developing unit that develops the electrostatic latent image formed on the image carrier by the exposure unit with toner, and the driver circuit of the exposure unit and the developing unit are disposed with a frame member therebetween. can do. The other end frame member that holds the exposure device on the other end side of the image carrier is further provided, and a drive system that rotationally drives the image carrier is disposed outside the other end frame member. can do. In this case, the frame member may be provided in front of the other end frame member. Further, the exposed surface of the driver circuit may be arranged upward.

  From another viewpoint, the print head to which the present invention is applied has a plurality of recording elements arranged in the main scanning direction and a plurality of recording elements attached to one end side in the main scanning direction. It includes a substrate having a portion that protrudes to the outside of the frame when mounted on the frame, and a driver circuit that is attached to the protruding portion of the substrate and drives a plurality of recording elements.

  Here, it may be characterized by further including a connector that is provided at a protruding portion of the board and is connected to a harness for supplying power and / or signals to the driver circuit. Further, the plurality of recording elements can be characterized by comprising an LED array in which a plurality of LED chips configured by arranging a plurality of LEDs (Light Emitting Diodes) in the main scanning direction are arranged in the main scanning direction.

  According to the present invention, when a print head in which a recording element and a driver circuit are integrally formed is used, heat generated in the driver circuit can be suppressed from being transferred to the recording element.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the accompanying drawings.
—Embodiment 1—
FIG. 1 is a diagram showing an overall configuration of an image forming apparatus according to Embodiment 1, and shows a so-called tandem type digital color copying machine. The image forming apparatus shown in FIG. 1 controls an image process system 10 that forms an image corresponding to gradation data of each color, a sheet conveyance system 30 that conveys recording paper (sheet), and the image process system 10 in the main body 1. The image output control unit 41 is connected to a personal computer, a scanner unit 45, or the like, and includes an IPS (Image Processing System) 42 that is an image processing system that performs predetermined image processing on received image data. FIG. 1 is a view of the image forming apparatus as viewed from the side where the user operates (front side).

  The image processing system 10 includes four image forming units 11Y and 11M of yellow (Y), magenta (M), cyan (C), and black (K), which are arranged in parallel at regular intervals in the horizontal direction. , 11C, 11K, and a transfer unit 20 for transferring the toner images of the respective colors formed on the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, 11K onto the intermediate transfer belt 21. Further, the main body 1 is provided with a fixing device 29 for fixing the image on the recording paper (sheet) secondarily transferred by the transfer unit 20 to the recording paper using heat and pressure. Further, toner cartridges 19Y, 19M, 19C, and 19K are provided for supplying toner of each color to the image forming units 11Y, 11M, 11C, and 11K.

  The transfer unit 20 includes a drive roll 22 that drives the intermediate transfer belt 21, a tension roll 23 that applies a constant tension to the intermediate transfer belt 21, and a backup roll that secondarily transfers the superimposed toner images of each color onto a recording sheet. 24, a belt cleaner 25 for removing residual toner and the like existing on the intermediate transfer belt 21 is provided. The intermediate transfer belt 21 is wound around the drive roll 22, the tension roll 23, and the backup roll 24 with a constant tension, and is rotated by a dedicated drive motor (not shown) having excellent constant speed. The drive roll 22 is circulated at a predetermined speed in the direction of the arrow. As the intermediate transfer belt 21, for example, a belt whose resistance is adjusted with a belt material (rubber or resin) that does not cause charge-up is used.

  The sheet conveyance system 30 is loaded with a recording sheet (sheet) on which an image is recorded and fed, a nudger roll 32 that picks up and feeds the recording sheet from the feeding tray 31, and a nudger roll 32. A feed roll 33 that separates and conveys the recording papers one by one, and a conveyance path 34 that conveys the recording paper separated one by one by the feed rolls 33 toward the image transfer unit. In addition, a registration roll 35 that conveys the recording paper conveyed through the conveyance path 34 toward the secondary transfer position in time, and a backup roll 24 that is provided at the secondary transfer position and is in pressure contact with the recording paper. A secondary transfer roll 36 for secondary transfer of the image onto the recording paper, a discharge paper 37 for discharging the recording paper on which the toner image is fixed by the fixing device 29 to the outside of the main body 1, and a recording paper discharged by the discharge roll 37 are stacked. A discharge tray 38 is provided.

  The scanner unit 45 reads an image of a document placed on the platen glass or an image of the document conveyed on the platen glass by a CCD image sensor or the like (not shown). Here, in the image forming apparatus according to the present embodiment, the scanner unit 45 is disposed on the upper side of the main body 1 to save space. Note that a predetermined gap is formed between the discharge tray 38 and the scanner unit 45 so that the recording paper after image formation discharged to the discharge tray 38 can be easily taken out.

  Next, the image forming units 11Y, 11M, 11C, and 11K in the image process system 10 will be described in detail. FIG. 2 is a diagram for explaining the configuration of the image forming units 11Y, 11M, 11C, and 11K. Here, a yellow (Y) image forming unit 11Y is shown. The other image forming units 11M, 11C, and 11K have substantially the same configuration except for the toner stored in the developing device 15.

  The image forming unit 11Y (11M, 11C, 11K) is charged by a photosensitive drum 12 as an image carrier for carrying a toner image, a charger 13 for charging the photosensitive drum 12 using a charging roll, and a charger 13. An LED print head (LPH) 14 as an exposure unit that irradiates the photosensitive drum 12 with light to form an electrostatic latent image on the photosensitive drum 12, and the electrostatic formed on the photosensitive drum 12 by the LPH 14. A developing unit 15 that develops a latent image with toner and a photosensitive drum 12 that are provided across the intermediate transfer belt 21 and a toner image developed on the photosensitive drum 12 are transferred to the intermediate transfer belt 21. A transfer roll 16 and a drum cleaner 17 for removing residual toner remaining on the photosensitive drum 12 after transfer are provided. Here, the developing unit 15 is opened at a position facing the photosensitive drum 12, and has a developing housing 15a in which a two-component developer containing toner and a carrier is accommodated, and a position facing the opening of the developing housing 15a. Is provided with a developing roll 15b disposed rotatably. The photosensitive drum 12 is rotationally driven in the direction A in the same direction as the moving direction of the intermediate transfer belt 21 at the portion facing the intermediate transfer belt 21, and the developing roller 15 b is photosensitive at the portion facing the photosensitive drum 12. The body drum 12 is rotationally driven in the B direction, which is the same direction as the rotational direction (A direction) of the body drum 12.

Further, the intermediate transfer belt 21 is disposed on the upper side in the vertical direction of the photoconductive drum 12, and the LPH 14 is disposed on the lower side in the vertical direction of the photoconductive drum 12.
In this embodiment, the photosensitive drum 12, the charger 13, the developing device 15, and the drum cleaner 17 are integrated into a process cartridge 18. As a result, only the process cartridge 18 can be removed from the main body 1 (see FIG. 1), and only the process cartridge 18 can be attached to the main body 1, allowing replacement by the user. The process cartridge 18 is attached to and detached from the main body 1 by a user or a serviceman accessing from the front side of the main body 1. For example, when the process cartridge 18 is attached to the main body 1, the process cartridge 18 is inserted from the front side to the back side of the main body 1, and when the process cartridge 18 is removed from the main body 1, the process cartridge 18 is inserted into the main body 1. The processed process cartridge 18 is pulled out from the back side to the front side.

  Next, the operation of the image forming apparatus will be described with reference to FIGS. For example, the color material reflected light image of the original read by the scanner unit 45 and the color material image data formed by a personal computer (not shown) are, for example, R (red), G (green), and B (blue). It is input to the IPS 42 as 8-bit reflectance data. In the IPS 42, the input reflectance data is subjected to predetermined image processing such as shading correction, position shift correction, brightness / color space conversion, gamma correction, frame deletion, color editing, moving editing, and other various image editing. Is done. The image data subjected to the image processing is converted into color material gradation data of four colors of yellow (Y), magenta (M), cyan (C), and black (K), and each image forming unit 11Y, 11M, It is output to the LPH 14 of 11C and 11K.

  In each of the image forming units 11Y, 11M, 11C, and 11K, the photosensitive drum 12 is charged to a predetermined potential by the charger 13. The LPH 14 of each of the image forming units 11Y, 11M, 11C, and 11K causes the corresponding LED to emit light according to the color material gradation data input from the IPS 42, and forms an image via the SELFOC (registered trademark) lens array. The photosensitive drums 12 of the units 11Y, 11M, 11C, and 11K are irradiated. On the photosensitive drum 12 of the image forming units 11Y, 11M, 11C, and 11K, the charged surface is exposed to form an electrostatic latent image. The formed electrostatic latent image is converted into each color of yellow (Y), magenta (M), cyan (C), and black (K) by the developing device 15 of each image forming unit 11Y, 11M, 11C, 11K. Developed as a toner image.

  The toner images formed on the respective photosensitive drums 12 of the image forming units 11Y, 11M, 11C, and 11K are multiple transferred onto the intermediate transfer belt 21. At this time, the black image forming unit 11 </ b> K that forms a black toner image is provided on the most downstream side in the moving direction of the intermediate transfer belt 21, and the black toner image is finally transferred to the intermediate transfer belt 21. Is done. Further, the photosensitive drums 12 of the image forming units 11Y, 11M, 11C, and 11K after the transfer are cleaned by the drum cleaner 17.

  On the other hand, in the sheet conveyance system 30, the nudger roll 32 rotates in synchronization with the image formation timing, and a recording paper of a predetermined size is supplied from the paper feed tray 31. The recording sheets separated one by one by the feed roll 33 are conveyed to the registration roll 35 through the conveyance path 34 and are temporarily stopped. Thereafter, the registration roll 35 rotates in accordance with the movement timing of the intermediate transfer belt 21 on which the toner image is formed, and the recording paper is conveyed to the secondary transfer position formed by the backup roll 24 and the secondary transfer roll 36. . On the recording sheet conveyed from the lower side to the upper side at the secondary transfer position, the toner images in which the four colors are multiplexed are sequentially transferred in the sub-scanning direction using a pressing force and a predetermined electric field. The recording paper on which the toner images of the respective colors are transferred is subjected to a fixing process by heat and pressure by the fixing device 29 and then discharged to a discharge tray 38 provided on the upper portion of the main body 1 by a discharge roll 37. On the other hand, the intermediate transfer belt 21 after the secondary transfer is cleaned by the belt cleaner 25 to prepare for the next process.

  Next, the LPH 14 will be described in detail. FIG. 3 shows an enlarged sectional view of the LPH 14 described above. The LPH 14 supports an LED array 51 formed by arranging a plurality of recording elements or a plurality of LEDs as a plurality of recording elements on a straight line in an LED array 56 (described later) in a staggered manner, and LED array 51. A printed circuit board 52 as a circuit board to which a driver IC (described later) for controlling the driving of the array 51 is attached, a support member 53 that supports the printed circuit board 52, and a light beam emitted from each LED on the photosensitive drum 12. A SELFOC (registered trademark) lens array 54 to be imaged, a support member 53 to which a printed circuit board 52 is attached, and an LPH housing 55 for holding the SELFOC lens array 54 are provided.

  FIGS. 4A and 4B are diagrams for explaining the structures of the SELFOC lens array 54 and the LED array 51. FIG. 4A is a diagram of the SELFOC lens array 54 viewed from the light emitting point side, and FIG. 4B shows the structure of the LED array 51 in which the LED chips 56 are arranged in a staggered manner. As shown in FIG. 4A, in the SELFOC lens array 54, SELFOC lenses 57 are arranged between the LPH housings 55 functioning as fixing side plates. However, “alignment” has periodic unevenness in optical characteristics (light transmittance) due to its structure. On the other hand, in the LED array 51, as shown in FIG. 4B, the LED chips 56 are arranged in a staggered pattern in two rows in the sub-scanning direction (y direction) on the printed circuit board 52. For example, the LED chip 56 that is a bundle of LEDs has 128 pixels of light emitting points arranged in one chip. When all the LED chips 56 are arranged in a straight line, the LED interval is set to a pixel interval (for example, 42.3 μm if 600 dpi) at the connection portion of the LED chip 56, so The interval becomes very narrow, and a defect that causes a chip or the like in the light emitting portion is likely to occur. Therefore, as shown in FIG. 4B, the LED chips 56 are arranged in a staggered manner to increase the distance between the cut surface of the chip end and the light emitting point, and is necessary in the main scanning direction (x direction). It is effective to arrange pixels. This staggered arrangement of LED chips 56 is advantageous particularly when high-density mounting of 1200 dpi or higher is required.

FIG. 5 is a hardware configuration diagram of the LPH 14 to which the present embodiment is applied. In the present embodiment, a self-scanning recording element (SLED) system using a thyristor as a switching element is employed. The LPH 14 receives video data from the IPS 42 (see FIG. 1) and supplies a lighting signal to each LED chip 56 constituting the LED array 51, and an image output control unit 41 (see FIG. 1). ) Is provided with a transfer signal generator 62 for generating a transfer signal in response to the clock and the synchronization signal from. The LPH 14 to which the present embodiment is applied has, for example, 60 LED chips 56 having 128 LEDs, and each LED chip 56 can emit LEDs of 128 dots and the LPH 14 as a whole, 7680 dots. It is. The LPH driving unit 61 generates 60 lighting signals (CKI1 to CKI60) for the 60 LED chips 56. The transfer signal generator 62 generates six transfer signals (CKS_1 to CKS_6) and transfer signals (CK1_1 to CK1_6, CK2_1 to CK2_6) every six sets. For example, in the example shown in FIG. 5, 128 LEDs are sequentially turned on in one main scan line according to the number of elements (number of dots) of each LED chip 56, and the LEDs are sequentially turned on. The maximum number of lighting is 60. The LPH driving unit 61 is connected to an EEPROM 63 that stores correction data for correcting the light quantity of each LED constituting each LED chip 56.
In this embodiment, the LPH driving unit 61, the transfer signal generating unit 62, and the EEPROM 63 described above are configured as a driver IC 64 that is one semiconductor integrated circuit. This driver IC 64 functions as a driver circuit.

  Here, FIG. 6 shows a perspective view of the LPH 14. In the LPH 14, LPH housings 55 are formed so as to protrude from both ends of the SELFOC lens array 54 in the main scanning direction. In the LPH housing 55, these protruding portions are referred to as a first protruding portion 55a and a second protruding portion 55b. Here, the 1st protrusion part 55a has a function as a site | part to protrude, and the 1st protrusion part 55a is set longer than the 2nd protrusion part 55b. Bolts 58a and 58b for positioning the LPH 14 with respect to a frame (not shown) provided on the main body 1 (see FIG. 1) are arranged in the projecting portions 55a and 55b in the vertical direction. Yes.

  FIG. 7 is an enlarged perspective view of one end side of the LPH 14 in FIG. 6 in the main scanning direction, specifically, the first projecting portion 55 a provided on the LPH housing 55. A printed circuit board 52 to which the LED array 51 (see FIGS. 3 and 4) is attached is arranged to extend above the first protrusion 55a. A driver IC 64 in which the LPH driving unit 61, the transfer signal generating unit 62, and the EEPROM 63 are integrated is attached to the upper surface of the printed circuit board 52 exposed on the first projecting portion 55a. Further, on the upper surface of the printed circuit board 52 between the driver IC 64 and the mounting position of the bolt 58a, a power line connector 65 as a connector for connecting a power cable 71 as a harness for supplying power to the driver IC 64, the LED array 51 and the like is arranged. It is installed. Further, a connector for receiving video data from the IPS 42 (see FIG. 1), a clock and a synchronizing signal from the image output control unit 41 (see FIG. 1), etc. on the upper surface of the printed circuit board 52 outside the mounting position of the bolt 58a. A signal line connector 66 is provided. A tape-shaped harness 72 is attached to the signal line connector 66. As described above, in the present embodiment, the driver IC 64 for driving the LED array 51 and the power source are disposed at one end side of the LPH 14 in the main scanning direction and substantially in series with the SELFOC lens array 54 (LED array 51). A power supply line connector 65 for supply and a signal line connector 66 for communication are arranged.

FIG. 8 is a view of FIG. 2 as viewed from the VIII direction, and shows a state in which the process cartridge 18 (see FIG. 1) and the LPH 14 are mounted on the main body 1 (see FIG. 1). However, in FIG. 8, the description of the developing housing 15a of the developing unit 15 constituting the process cartridge 18 is omitted, and only the photosensitive drum 12 and the developing roll 15b of the developing unit 15 are illustrated.
Here, the main body 1 has a front frame 81 as a frame member or a frame provided on the front side of the main body 1 and a rear frame 82 as a second end frame member provided on the back side. The process cartridge 18 is positioned by being inserted from the front side to the back side of the main body 1, and in the positioned state, both ends of the photosensitive drum 12 and the developing roll 15b in the axial direction are positioned. Is fixed between the front frame 81 and the rear frame 82. Further, a gear 12b is provided on the back side of the rotation shaft 12a, which is the rotation center of the photosensitive drum 12, and a gear 12c is provided on the back side. Here, the gear 12b is arranged on the front side of the rear frame 82, and the gear 12c is arranged on the back side of the rear frame 82. On the other hand, a gear 15d is provided on the back side of the rotation shaft 15c, which is the rotation center of the developing roll 15b, so as to mesh with the gear 12b. It is supposed to be. A drive gear 83 as a drive system that meshes with the gear 12 c provided on the photosensitive drum 12 when the process cartridge 18 is inserted is provided behind the rear frame 82 of the main body 1. The driving gear 83 applies a driving force applied by a driving motor (not shown) provided in the main body 1 to the rotating shaft 12 a of the photosensitive drum 12. Although only the drive gear 83 is shown here, more drive gears are actually provided.

  The LPH 14 is also positioned by being inserted from the front side of the main body 1 toward the back side. Here, in the present embodiment, the LPH 14 is positioned by fitting the second protrusion 55b on the rear frame 82 side. In the present embodiment, when the LPH 14 is positioned, the first protrusion 55a is exposed on the front side of the front frame 81. That is, the driver IC 64, the power line connector 65 (power cable 71), and the signal line connector 66 (harness 72) provided on the first projecting portion 55 a are arranged on the front side of the front frame 81. . That is, the driver IC 64 and the LED array 51 are arranged across the front frame 81. Further, the driver IC 64 and the photosensitive drum 12 are arranged with the front frame 81 therebetween. Further, the driver IC 64 and the developing device 15 (developing roll 15b) are arranged with the front frame 81 therebetween.

  In the LPH 14 according to the present embodiment, the driver IC 64 generates heat during the image forming operation. At this time, the heat generated by the driver IC 64 is blocked by the front frame 81 and is not easily transmitted to the space formed between the front frame 81 and the rear frame 82. Thereby, the expansion | swelling and twist of the LED array 51 arrange | positioned between the front frame 81 and the rear frame 82 are suppressed, and the light quantity fluctuation | variation of LED becomes difficult to generate | occur | produce. In addition, the photosensitive drum 12 disposed between the front frame 81 and the rear frame 82 is also less susceptible to the heat generated by the driver IC 64, so that the photosensitive layer is not deteriorated. Further, since the developing device 15 (developing roll 15b) is also disposed between the front frame 81 and the rear frame 82, a so-called toner blocking phenomenon in which the toner in the developing device 15 is melted and fixed by heat generated by the driver IC 64. Is also suppressed.

  In this embodiment, the LPH 14 is disposed below the photosensitive drum 12, and the driver IC 64 provided on the LPH 14 is attached to the side where the SELFOC lens array 54 is provided, that is, the side where the LED array 51 is provided. It has been. As a result, the driver IC 64 is arranged such that the upper surface (exposed surface) of the package faces upward. For this reason, the heat generated by the driver IC 64 can easily escape to the upper side naturally, and the heat dissipation characteristics can be improved. Therefore, the occurrence of displacement of the latent image forming position due to the expansion or twist of the LPH 14 itself due to heat can be further suppressed.

  Further, in the present embodiment, the power line connector 65 and the signal line connector 66 are disposed adjacent to the driver IC 64. Therefore, even after the LPH 14 is attached to the main body 1, the user or service person can easily access the power line connector 65 and the signal line connector 66 from the front side. Thereby, attachment and removal of the power cable 71 and the harness 72 are facilitated. Furthermore, in the LPH 14 according to the present embodiment, since the signal line connector 66 is disposed close to the driver IC 64, the distance between the two can be shortened. As a result, it is possible to reduce the influence of noise generated around the driver IC 64 and the signal line connector 66, and to prevent malfunctions and the like.

  In particular, in the image forming apparatus according to the present embodiment, since the scanner unit 45 is disposed on the main body 1 as shown in FIG. 1, after the image forming apparatus is installed, the main body 1 starts from the upper side of the main body 1. It is difficult to access inside. In the image forming apparatus according to the present embodiment, the drive system such as the photosensitive drum 12 is disposed behind the rear frame 82 provided in the main body 1. It is difficult to arrange the cable 71 and the harness 72. On the other hand, in this embodiment, since the power cable 71 and the harness 72 are arranged on the front side of the main body 1, it is possible to access from the front side of the main body 1, thereby improving the maintainability. it can.

  In this embodiment, the example in which the LPH 14 is disposed on the lower side of the photosensitive drum 12 has been described. However, depending on the configuration of the image forming apparatus, the LPH 14 may be disposed on the upper side of the photosensitive drum 12. There is also a possibility. In such a case, in order to release the heat generated by the driver IC 64 to the upper side, the driver IC 64 provided in the LPH 14 is provided on the side opposite to the side where the SELFOC lens array 54 is provided, and a space is provided above the driver IC 64. It is preferable to form.

  In this embodiment, the LPH 14 (print head) that controls the blinking of the LED by the driver IC 64 has been described. However, the present invention is not limited to this. For example, the driver IC controls the opening and closing of the optical shutter. The same applies to the print head. The same applies to not only a print head using an optical recording method, but also an inkjet head (print head) in which a plurality of nozzles are arranged in parallel and the ejection of ink from the plurality of nozzles is driven and controlled by a driver IC. Applicable to.

1 is a diagram illustrating an overall configuration of an image forming apparatus to which the exemplary embodiment is applied. It is a figure for demonstrating the structure of an image forming unit. It is an expanded sectional view of LPH. (a), (b) is a figure for demonstrating the structure of a SELFOC lens array and an LED array. It is a hardware block diagram of LPH. It is a perspective view of LPH. It is an expansion perspective view of the main scanning direction one end side of LPH. FIG. 3 is a diagram for explaining a state in which LPH is attached to the main body of the image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body, 10 ... Image process system, 11 (11Y, 11M, 11C, 11K) ... Image forming unit, 12 ... Photosensitive drum, 13 ... Charger, 14 ... LED print head (LPH), 15 ... Developer 15 ... Development roll, 16 ... Primary transfer roll, 17 ... Drum cleaner, 18 ... Process cartridge, 20 ... Transfer unit, 29 ... Fixer, 41 ... Image output control unit, 42 ... IPS (Image Processing System), 45 ... Scanner Unit: 51 ... LED array, 52 ... Printed circuit board, 53 ... Support member, 54 ... Selfoc lens array, 55 ... LPH housing, 55a ... First protrusion, 55b ... Second protrusion, 56 ... LED chip, 57 ... Selfoc lens, 61 ... LPH drive unit, 62 ... Transfer signal generation unit, 63 ... EEPROM, 64 ... Driver IC, 65 ... Power supply line Connector, 66 ... signal line connector, 71 ... power cable, 72 ... harness, 81 ... front frame, 82 ... rear frame, 83 ... driving gear

Claims (4)

An image carrier disposed rotatably;
More than a plurality of recording elements disposed below the image carrier and arranged along the axial direction of the image carrier facing the image carrier, and one end of the plurality of recording elements in the arrangement direction An exposure device that is integrally formed by attaching a driver circuit that is disposed outside and drives the plurality of recording elements to the same substrate, and that exposes the image carrier;
A frame member that holds the exposure device at one axial end of the image carrier,
The image forming apparatus, wherein the plurality of recording elements of the exposure device and the driver circuit are arranged with the frame member interposed therebetween , and the driver circuit is attached at a position above the substrate .   The image forming apparatus according to claim 1, wherein the driver circuit of the exposure device and the image carrier are arranged with the frame member therebetween. A developing device for developing the electrostatic latent image formed on the image carrier by the exposure device with toner;
3. The image forming apparatus according to claim 1 , wherein the driver circuit of the exposure device and the developing device are arranged with the frame member therebetween. A second end frame member that holds the exposure device on the other end side of the image carrier;
The exposure unit is attached by being inserted from the frame member side toward the other end frame member side, and is removed by being extracted from the other end frame member side toward the frame member side. Made,
4. The image forming apparatus according to claim 1 , wherein a drive system that rotationally drives the image carrier is disposed outside the other end frame member. 5.

Images