Light emitting device, light emitting element array chip, and exposure device

Abstract

Provided are a light emitting device, a light emitting element array chip, and an exposure device. The light emitting device includes: a first light emitting element column including light emitting elements arranged in a column in a main scanning direction; and a second light emitting element column including light emitting elements arranged in a column in the main scanning direction, at least a portion of which overlaps the first light emitting element column in a sub scanning direction, the first light emitting element column and the second light emitting element column being configured by arranging a light emitting element array chip in which light emitting elements are arranged in a column in the main scanning direction, and in which, in a central region of the light emitting elements arranged in a column, a pitch between the light emitting elements is switched from a first pitch to a second pitch different from the first pitch.

Description

TECHNICAL FIELD

[0001] The present application relates to a light emitting device, a light emitting element array chip, and an exposure apparatus. BACKGROUND

[0002] In an image forming apparatus such as a printer, a copier, a facsimile, or the like using an electrophotographic system, image information is irradiated on a charged photoreceptor by a light recording unit, and an electrostatic latent image is obtained. Then, toner is attached to the electrostatic latent image to make it visible, and image formation is performed by transferring and fixing it to a recording medium. As such a light recording unit, in addition to a light scanning system in which a laser is used to scan laser light in a main scanning direction to perform exposure, a light recording unit using a light emitting element head configured by arranging a plurality of light emitting elements such as LEDs (Light Emitting Diodes) in the main scanning direction has been used in recent years.

[0003] In Japanese Patent Application Publication No. 2012-166541, a light emitting element head is described, which is characterized in that the light emitting element head has a light emitting portion and a rod lens array, the light emitting portion has a first light emitting element column configured by light emitting elements arranged in a column in a main scanning direction, and a second light emitting element column configured by light emitting elements arranged in a column in the main scanning direction and at least partially arranged in overlap with the first light emitting element column in a sub-scanning direction, the rod lens array is used to image light output of the light emitting elements and expose a photoreceptor to form an electrostatic latent image, and the interval of the light emitting elements of the first light emitting element column is different from the interval of the light emitting elements of the second light emitting element column at a portion where the first light emitting element column and the second light emitting element column overlap. SUMMARY

[0004] However, it is difficult to manufacture a light emitting element head in which all light emitting elements are arranged in the main scanning direction on one substrate. Therefore, a method in which a plurality of substrates are partially overlapped in the sub-scanning direction and arranged in a staggered manner in the main scanning direction, and the light emission is switched at the overlapped portion is sometimes used. However, in this case, the light emitting elements on each substrate are sometimes arranged in offset in the main scanning direction at the overlapped portion.

[0005] An object of the present application is to provide a light emitting device and the like in which, compared to a case where a light emitting element array chip in which the interval between light emitting elements in a central region of light emitting elements arranged in a column is switched from a first interval to a second interval different from the first interval is not used, it is difficult for light emitting elements on each substrate to be arranged in offset in the main scanning direction at a switching portion.

[0006] According to a first aspect of the present disclosure, there is provided a light emitting device, including: a first light emitting element column configured with light emitting elements arranged in a column in a main scanning direction; and a second light emitting element column configured with light emitting elements arranged in a column in the main scanning direction, at least a portion of which overlaps the first light emitting element column in a sub-scanning direction, the first light emitting element column and the second light emitting element column being configured by arranging light emitting element array chips, the light emitting element array chips being configured with light emitting elements arranged in a column in the main scanning direction, and in the light emitting element array chips, a pitch between light emitting elements is switched from a first pitch to a second pitch different from the first pitch in a central region of the light emitting elements arranged in a column.

[0007] According to a second aspect of the present disclosure, at least a portion of an overlapping region in which the first light emitting element column and the second light emitting element column overlap, light emitting elements arranged at the first pitch and light emitting elements arranged at the second pitch are opposed.

[0008] According to a third aspect of the present disclosure, in the overlapping region, the light emitting element array chips having the same arrangement of light emitting elements are opposed in opposite directions, so that light emitting elements arranged at the first pitch and light emitting elements arranged at the second pitch are opposed.

[0009] According to a fourth aspect of the present disclosure, a width of the light emitting element array chips opposed in opposite directions in the main scanning direction is more than half of an arrangement width of light emitting elements configuring the light emitting element array chips.

[0010] According to a fifth aspect of the present disclosure, in a region in which light emitting elements configuring the first light emitting element column and light emitting elements configuring the second light emitting element column are aligned in the sub-scanning direction at an arbitrary position in the overlapping region, the first light emitting element column and the second light emitting element column are switched to emit light.

[0011] According to a sixth aspect of the present disclosure, the light emitting element array chips are arranged in the overlapping region in which the first light emitting element column and the second light emitting element column overlap.

[0012] According to a seventh aspect of the present disclosure, the light emitting element array chips are used not only in the overlapping region but also in all regions in the main scanning direction, so that the first light emitting element column and the second light emitting element column are configured with the same kind of light emitting element array chips.

[0013] According to a 8th aspect of the present disclosure, a toner image is formed from an electrostatic latent image formed by light emission, the light emission device further having: a transfer unit that transfers the toner image onto a recording medium; a fixing unit that fixes the toner image transferred onto the recording medium, forming an image; and a switching unit that causes the first light emission element column and the second light emission element column to emit light in a switched manner at a switching position provided at any position of an overlapping position of the first light emission element column and the second light emission element column.

[0014] According to a 9th aspect of the present disclosure, there is provided a light emission element array chip, wherein the light emission element array chip has: a light emission element column constituted by light emission elements arranged in a column shape in a main scanning direction; and a driving section for inputting and outputting a signal for driving the light emission elements, and in a central region of the light emission elements arranged in a column shape, a pitch between the light emission elements is switched from a first pitch to a second pitch different from the first pitch.

[0015] According to a 10th aspect of the present disclosure, there is provided an exposure device having: the light emission device; and an optical element for imaging light output from the light emission elements, exposing a photoreceptor, forming an electrostatic latent image.

[0016] (EFFECTS)

[0017] According to the 1st aspect of the present disclosure, compared to a case where a light emission element array chip in which a pitch between light emission elements in a central region of light emission elements arranged in a column shape is switched from a first pitch to a second pitch different from the first pitch is not used, it is possible to provide a light emission device in which light emission elements on each substrate at a switching position are difficult to be arranged misaligned in a main scanning direction.

[0018] According to the 2nd aspect, resolution at the switching position is made higher.

[0019] According to the 3rd aspect, it is possible to use the same light emission element array chip at the switching position.

[0020] According to the 4th aspect described above, in a sub-scanning direction, the light emission elements are easily aligned.

[0021] According to the 5th or 6th aspect described above, it is difficult to generate black or white stripes at the switching position.

[0022] According to the 7th aspect described above, it is possible to unify the light emission element array chip used to the same chip.

[0023] According to the 8th aspect described above, it is possible to provide a light emission device in which it is difficult to generate black or white stripes in an image formed on a recording medium.

[0024] According to the ninth aspect described above, it is possible to provide a light emitting element array chip in which light emitting elements on each substrate are less likely to be misaligned in the main scanning direction when used at a switching position.

[0025] According to the tenth aspect described above, it is possible to provide an exposure apparatus in which image shift is less likely to occur on a latent image formed on a photoreceptor. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a diagram showing an outline of an image forming apparatus of the present embodiment.

[0027] Figure 2 shows a configuration of a light emitting element head to which the present embodiment is applied.

[0028] Figure 3 (a) of is a perspective view of a circuit board and a light emitting portion of a light emitting element head; Figure 3 (b) of is a view of the light emitting portion as viewed from the IIIb direction of (a) and is a view in which a part of the light emitting portion is enlarged.

[0029] Figure 4 (a) to (b) of is a diagram showing a configuration of a light emitting chip to which the present embodiment is applied.

[0030] Figure 5 is a diagram showing a configuration of a signal generating circuit and a wiring structure of a circuit board when a self-scanning type light emitting element array chip is used as a light emitting chip.

[0031] Figure 6 is a diagram for explaining a circuit configuration of a light emitting chip.

[0032] Figure 7 (a) to (c) of is a diagram showing a case where black or white stripes are generated in an image formed on a paper P due to a change in pitch of LEDs at a switching position.

[0033] Figure 8 is a diagram showing an arrangement of LEDs constituting a light emitting chip.

[0034] Figure 9 (a) of is a diagram for explaining a configuration example of a light emitting chip of a joint portion; Figure 9 (b) to (c) of is a diagram for explaining a width in which light emitting chips overlap in a main scanning direction.

[0035] Figure 10 is Figure 9 is an enlarged view of a periphery of a switching position of (a).

[0036] Figure 11 (a) to (b) of is a diagram showing a configuration of a light emitting chip.

[0037] Figure 12 Fig. 1 is a view showing another example of a light emitting device.

[0038] Figure 13 Fig. 2 is a view showing still another example of a light emitting device. DETAILED DESCRIPTION

[0039] <Explanation of overall structure of image forming apparatus>

[0040] Hereinafter, an embodiment of the present disclosure will be explained in detail with reference to the drawings.

[0041] Figure 1 Fig. 1 is a view showing an outline of an image forming apparatus 1 of the present embodiment.

[0042] The image forming apparatus 1 is an image forming apparatus generally called a tandem type. The image forming apparatus 1 has an image forming section 10 that forms an image in correspondence with image data of each color. Further, the image forming apparatus 1 includes an intermediate transfer belt 20 that sequentially transfers (primary transfer) and holds toner images of each color component formed by each image forming unit 11. The image forming apparatus 1 also includes a secondary transfer device 30 that transfers (secondary transfer) the toner images transferred to the intermediate transfer belt 20 all at once to a sheet P as an example of a recording medium. The image forming apparatus 1 also includes a fixing device 50 that is an example of a fixing unit for fixing the toner images secondary transferred to the sheet P and forming an image. Further, the image forming apparatus 1 includes an image output control section 200 that controls each mechanism section of the image forming apparatus 1 and performs predetermined image processing on image data.

[0043] For example, the image forming section 10 includes a plurality of (four in the present embodiment) image forming units 11 (specifically, 11Y (yellow), 11M (magenta), 11C (cyan), and 11K (black)) that form toner images of each color component in an electrophotographic manner. The image forming unit 11 is an example of a toner image forming unit that forms a toner image.

[0044] The image forming units 11 (11Y, 11M, 11C, and 11K) have the same configuration except for the color of the toner used. Therefore, the yellow image forming unit 11Y will be described as an example. The yellow image forming unit 11Y has a photosensitive drum 12 having a photosensitive layer not shown and rotatable in the direction of the arrow A. A charging roller 13, a light emitting element head 14, a developer 15, a primary transfer roller 16, and a drum cleaner 17 are provided around the photosensitive drum 12. Among them, the charging roller 13 is rotatably arranged in contact with the photosensitive drum 12 and charges the photosensitive drum 12 to a predetermined potential. The light emitting element head 14 irradiates light to the photosensitive drum 12 charged to the predetermined potential by the charging roller 13 to write an electrostatic latent image. The developer 15 houses a corresponding color component toner (yellow toner in the yellow image forming unit 11Y) and develops the electrostatic latent image on the photosensitive drum 12 with the toner. The primary transfer roller 16 primary transfers the toner image formed on the photosensitive drum 12 to the intermediate transfer belt 20. The drum cleaner 17 removes the residue (toner, etc.) on the photosensitive drum 12 after the primary transfer.

[0045] The photosensitive drum 12 functions as an image holding body that holds an image. In addition, the charging roller 13 functions as a charging unit that charges the surface of the photosensitive drum 12, and the light emitting element head 14 functions as an electrostatic latent image forming unit (light emitting device, exposure device) that forms an electrostatic latent image by exposing the photosensitive drum 12 to light. Furthermore, the developer 15 functions as a developing unit that develops the electrostatic latent image to form a toner image.

[0046] The intermediate transfer belt 20, which is an image transfer body, is rotatably tensioned by a plurality of (five in the present embodiment) support rollers. Among these support rollers, the drive roller 21 tensioning the intermediate transfer belt 20 and drives the intermediate transfer belt 20 to rotate. The tension rollers 22 and 25 tension the intermediate transfer belt 20 and rotate with the intermediate transfer belt 20 driven by the drive roller 21. The correction roller 23 functions as a turning roller (freely tiltable with the axial one end portion as a fulcrum) that tensions the intermediate transfer belt 20 and restricts the meandering of the intermediate transfer belt 20 in a direction substantially perpendicular to the conveyance direction of the intermediate transfer belt 20. In addition, the support roller 24 tensions the intermediate transfer belt 20 and functions as a component of the secondary transfer device 30 described later.

[0047] The belt cleaner 26 that removes the residue (color toner, etc.) on the intermediate transfer belt 20 after the secondary transfer is provided at a position opposite the drive roller 21 across the intermediate transfer belt 20.

[0048] Details will be described later, but in the present embodiment, the image forming unit 11 forms a density correction image (reference patch, density correction toner image) based on a predetermined density for correcting the image density. This density correction image is an example of an image that adjusts the state of the device.

[0049] The secondary transfer device 30 includes a secondary transfer roller 31 that is in pressure contact with the toner image holding surface side of the intermediate transfer belt 20, and a backup roller 24 that is disposed on the back surface side of the intermediate transfer belt 20 and constitutes the counter electrode of the secondary transfer roller 31. A power supply roller 32 for applying a secondary transfer bias of the same polarity as the polarity of the toner is disposed in contact with the backup roller 24. On the other hand, the secondary transfer roller 31 is grounded.

[0050] In the image forming device 1 of the present embodiment, a transfer unit that transfers a toner image onto a sheet P is constituted by the intermediate transfer belt 20, the primary transfer roller 16, and the secondary transfer roller 31.

[0051] Further, the sheet conveying system includes a sheet tray 40, a conveying roller 41, a registration roller 42, a conveying belt 43, and a discharge roller 44. In the sheet conveying system, after the sheets P stacked on the sheet tray 40 are conveyed by the conveying roller 41, the sheets P are temporarily stopped at the registration roller 42, and then the sheets P are fed to the secondary transfer position of the secondary transfer device 30 at a predetermined timing. Further, the sheets P after secondary transfer are conveyed to the fixing device 50 by the conveying belt 43, and the sheets P discharged from the fixing device 50 are fed out to the outside of the device by the discharge roller 44.

[0052] Next, the basic image forming process of the image forming apparatus 1 will be described. Now, if the start switch operation other than the illustration is turned on, predetermined image forming process is executed. Specifically, for example, in the case where the image forming apparatus 1 is configured as a printer, the image output control section 200 first receives image data externally input from a PC (personal computer) or the like. The received image data is subjected to image processing by the image output control section 200, and is supplied to the image forming units 11. Then, the image forming units 11 form toner images of respective colors. That is, the respective image forming units 11 (specifically, 11Y, 11M, 11C, and 11K) are driven in accordance with digital image signals of respective colors. Next, in the respective image forming units 11, light corresponding to the digital image signals is irradiated by the light emitting element head (LPH) 14 to the photosensitive drums 12 charged by the charging roller 13, so that electrostatic latent images are formed. Then, the developer 5 develops the electrostatic latent images formed on the photosensitive drums 12, so that toner images of respective colors are formed. In the case where the image forming apparatus 1 is configured as a copier, a document placed on a document table not illustrated is read by a scanner, and the obtained read signal is converted into a digital image signal by a processing circuit, after which the formation of toner images of respective colors is performed in the same manner as described above.

[0053] Then, the toner images formed on the respective photosensitive drums 12 are sequentially primary-transferred to the surface of the intermediate transfer belt 20 by the primary transfer roller 16 at a primary transfer position where the photosensitive drums 12 meet the intermediate transfer belt 20. On the other hand, the toner remaining on the photosensitive drums 12 after the primary transfer is cleaned by the drum cleaner 17.

[0054] In this way, the toner images primary-transferred to the intermediate transfer belt 20 are overlaid on the intermediate transfer belt 20, and are conveyed to a secondary transfer position as the intermediate transfer belt 20 rotates. On the other hand, the paper sheet P is conveyed to the secondary transfer position at a predetermined timing, and the secondary transfer roller 31 pinches the paper sheet P between the support roller 24 and the secondary transfer roller 31.

[0055] Further, at the secondary transfer position, the toner images on the intermediate transfer belt 20 are secondary-transferred to the paper sheet P by the action of a transfer electric field formed between the secondary transfer roller 31 and the support roller 24. The paper sheet P on which the toner images are transferred is conveyed to the fixing device 50 by the conveyance belt 43. In the fixing device 50, the toner images on the paper sheet P are fixed by being heated and pressed, after which the paper sheet P is discharged to a paper discharge tray (not illustrated) provided outside the apparatus. On the other hand, the toner remaining on the intermediate transfer belt 20 after the secondary transfer is cleaned by the belt cleaner 26.

[0056] <Description of Light Emitting Element Head 14>

[0057] Figure 2This is a diagram showing the structure of the light-emitting element head 14 according to this embodiment.

[0058] The light-emitting element head 14 is an example of a light-emitting device, comprising: a housing 61; a light-emitting part 63 having a plurality of LEDs as light-emitting elements; and a circuit board 62 on which the light-emitting part 63 and a signal generating circuit 100 (described later) are mounted. Figure 3 ), etc.; and a rod lens (radial refractive index distribution type lens) array 64, which is an example of an optical element for imaging the light emitted from an LED and exposing a photoreceptor to form an electrostatic latent image.

[0059] The housing 61 is made of metal, for example, and supports the circuit board 62 and the rod lens array 64, and is configured such that the light-emitting point of the light-emitting part 63 coincides with the focal plane of the rod lens array 64. In addition, the rod lens array 64 is arranged along the axial direction (main scanning direction) of the photosensitive drum 12.

[0060] <Explanation of Light-emitting Part 63>

[0061] Figure 3 (a) is a perspective view of the circuit board 62 and the light-emitting part 63 in the light-emitting element head 14.

[0062] like Figure 3 As shown in (a), the light-emitting part 63 includes LPH bars 631a to 631c, focus adjustment pins 632a to 632b and a signal generation circuit 100, which is an example of a driving part for inputting and outputting signals to drive the LED.

[0063] LPH strips 631a to 631c are arranged alternately on the circuit board 62 along the main scanning direction. Furthermore, two adjacent LPH strips 631a to 631c along the main scanning direction are arranged to partially overlap in the sub-scanning direction, thereby forming connector portions 633a to 633b. In this case, connector portion 633a is formed by overlapping LPH strips 631a and 631b along the sub-scanning direction, and connector portion 633b is formed by overlapping LPH strips 631b and 631c along the sub-scanning direction.

[0064] In the following text, without distinguishing between LPH strips 631a to 631c, they may be referred to simply as LPH strip 631. Similarly, without distinguishing between focus adjusting pins 632a to 632b, they may be referred to simply as focus adjusting pin 632. Furthermore, without distinguishing between connector portions 633a to 633b, they may be referred to simply as connector portion 633.

[0065] Figure 3 (b) is from Figure 3The image (a) showing the light-emitting part 63 viewed from direction IIIb is a magnified view of a portion of the light-emitting part 63. Figure 3 In (b), the joint 633a of LPH strips 631a and 631b is shown.

[0066] like Figure 3 As shown in (b), light-emitting chips C, as an example of a light-emitting element array chip, are arranged in LPH strips 631a and 631b. The light-emitting chips C are arranged in two opposing staggered columns along the main scanning direction. For example, 60 light-emitting chips C are provided in each of LPH strips 631a and 631b. These 60 light-emitting chips C are sometimes referred to as light-emitting chips C1 to C60 in the following text. Furthermore, as shown, LEDs 71 are arranged on the light-emitting chips C. That is, in this case, the LEDs 71 are mounted on the light-emitting chips C in a predetermined number and arranged along the main scanning direction. The LEDs 71 are sequentially lit in each light-emitting chip C along the main scanning direction or in the opposite direction to the main scanning direction.

[0067] Furthermore, although not shown here, LPH strip 631c has the same construction as LPH strips 631a and 631b. Moreover, joint portion 633b also has the same construction as joint portion 633a.

[0068] Based on the above-described structure, the plurality of LEDs 71 disposed on LPH strips 631a and 631c can be understood as a first light-emitting element column consisting of LEDs 71 arranged in a column along the main scanning direction. Furthermore, the plurality of LEDs 71 disposed in LPH strip 631b can be understood as a second light-emitting element column, which is composed of at least a portion of LEDs 71 that overlap with the first light-emitting element column in the sub-scanning direction and are arranged in a column along the main scanning direction.

[0069] In addition, the connectors 633a to 633b can be understood as an example of the overlapping portion of the first light-emitting element column and the second light-emitting element column.

[0070] Furthermore, it can be said that the first light-emitting element column and the second light-emitting element column are respectively composed of light-emitting chips C with LEDs 71 arranged in the main scanning direction.

[0071] Furthermore, in the connector sections 633a to 633b, at a switching point Kp located at any position within this section, the first and second light-emitting element columns are switched to emit light. That is, at the switching point Kp, the LPH strip 631 to be illuminated is switched. In this case, the sequence of LPH strips 631 illuminating the LED 71 is LPH strip 631a → LPH strip 631b → LPH strip 631c.

[0072] In Figure 3 (b) of FIG. 17, the LED 71 illustrated with a white circle is lit, and the LED 71 illustrated with a black circle is not lit. That is, Figure 3 (b) of FIG. 17 shows that the lit LED is switched from the LED 71 of the LPH strip 631a to the LED 71 of the LPH strip 631b at the switching site Kp. On the left side of the switching site Kp in the figure, the LED 71 of the LPH strip 631a is lit, and on the right side of the switching site Kp in the figure, the LED 71 of the LPH strip 631b is lit.

[0073] The switching site Kp can be freely set in the joint portion 633a or the joint portion 633b, and the control of the switching is performed by the signal generating circuit 100. Thereby, the signal generating circuit 100 functions as a switching unit that causes the first light emitting element column and the second light emitting element column to emit light in a switched manner at the switching site Kp.

[0074] By the focus adjustment pins 632a to 632b, the circuit board 62 can be moved in the up-and-down direction indicated by the double-headed arrow in Figure 4 (a) of FIG. 17. That is, the circuit board 62 can be raised and lowered. Also, by raising and lowering the circuit board 62, the distance between the light emitting portion 63 and the photoreceptor can be changed. Therefore, the distance between the LPH strips 631a to 631c and the photoreceptor is changed, and the focus of the light output from the LED 71 and forming an image on the photoreceptor can be adjusted. Further, by the focus adjustment pins 632a to 632b, the circuit board 62 can be moved upward in both the focus adjustment pin 632a side and the focus adjustment pin 632b side. Alternatively, the circuit board 62 can be moved downward in both the focus adjustment pin 632a side and the focus adjustment pin 632b side. Also, either one of the focus adjustment pin 632a side and the focus adjustment pin 632b side can be moved upward, and the other side can be moved downward. The focus adjustment pins 632a to 632b can be operated by the control of the signal generating circuit 100, or can be operated manually.

[0075] <Explanation of light emitting element array chip>

[0076] Figure 4 (a) of FIG. 17 and Figure 4 (b) of FIG. 17 show the structure of the light emitting chip C to which the present embodiment is applied.

[0077] Figure 4 (a) of FIG. 17 is a view of the light emitting chip C as viewed from the direction in which light is emitted from the LED. Also, Figure 4 (b) of FIG. 17 is Figure 2 (a) of FIG. 17 is a view of the light emitting chip C as viewed from the direction in which light is emitted from the LED. Also,

[0078] In the light emitting chip C, as an example of the light emitting element array, a plurality of LEDs 71 arranged in a column in the main scanning direction form a light emitting element column. The light emitting chip C of the present embodiment switches the pitch of the LEDs 71 in the central region of the column of LEDs 71, which will be described later in detail. In addition, in the light emitting chip C, on both sides of the substrate 70, pads 72 as an example of an electrode portion for inputting or outputting a signal for driving the light emitting element array are arranged in a manner sandwiching the light emitting element array. Further, on the light exit side of each LED 71, a microlens 73 is formed. By the microlens 73, light emitted from the LED 71 is condensed, and light can be efficiently incident on the photosensitive drum 12 (refer to Figure 5 ).

[0079] The microlens 73 is composed of a transparent resin such as a photocurable resin, and in order to more efficiently condense light, the surface thereof is preferably in a non-spherical shape. In addition, the size, thickness, focal length, and the like of the microlens 73 are determined by the wavelength of the LED 71 used, the refractive index of the photocurable resin used, and the like.

[0080] <Explanation of Self-Scanning Light Emitting Element Array Chip>

[0081] In the present embodiment, it is preferable to use a self-scanning light emitting element array (SLED) chip as the light emitting element array chip exemplified as the light emitting chip C. The self-scanning light emitting element array chip uses a light emitting thyristor having a pnpn structure as a constituent element of the light emitting element array chip, and can achieve self-scanning of the light emitting element.

[0082] Figure 1 is a diagram showing the structure of the signal generating circuit 100 and the wiring structure of the circuit substrate 62 in the case where the self-scanning light emitting element array chip is used as the light emitting chip C.

[0083] Various control signals such as a line synchronization signal Lsync, image data Vdata, a clock signal clk, and a reset signal RST are input from the image output control section 200 (refer to Figure 6 ) to the signal generating circuit 100. Then, the signal generating circuit 100 performs, for example, rearrangement of the image data Vdata or correction of the output value, and the like, in accordance with the various control signals input from the outside, and outputs light emitting signals In the present embodiment, each light emitting signal is provided to each light emitting chip C (C1 to C60) one by one.

[0084] Further, the signal generating circuit 100 outputs a start transfer signal to the light emitting chips C1 to C60 based on the various control signals input from the outside First transmission signal Second transmission signal

[0085] The circuit board 62 is provided with a power supply line 101 (Vcc = -5.0V) for power supply connected to the Vcc terminal of each light-emitting chip C1 to C60, and a grounding power supply line 102 connected to the GND terminal. Furthermore, the circuit board 62 also includes a start transmission signal for the signal generation circuit 100. First transmission signal Second transmission signal The circuit board 62 includes a start signal line 103, a first signal line 104, and a second signal line 105. Furthermore, a circuit board 62 is also provided for outputting light-emitting signals from the signal generation circuit 100 to the light-emitting chips C (C1 to C60). The circuit board 62 has 60 light-emitting signal lines 106 (106_1 to 106_60). Additionally, 60 light-emitting current limiting resistors RID are provided on the circuit board 62 to prevent excessive current from flowing through the 60 light-emitting signal lines 106 (106_1 to 106_60). Furthermore, as described below, the light-emitting signal... It can be in two states: high level (H) and low level (L). The low level is a potential of -5.0V, and the high level is a potential of ±0.0V.

[0086] Figure 5 This is a diagram used to illustrate the circuit structure of the light-emitting chip C (C1 to C60).

[0087] The light-emitting chip C includes 60 transmitting thyristors S1 to S60 and 60 light-emitting thyristors L1 to L60. Furthermore, the light-emitting thyristors L1 to L60 have the same pnpn connection as the transmitting thyristors S1 to S60, and function as light-emitting diodes (LEDs) by utilizing their pn connections. Additionally, the light-emitting chip C includes 59 diodes D1 to D59 and 60 resistors R1 to R60. Furthermore, the light-emitting chip C has current-limiting resistors R1A, R2A, and R3A, which prevent excessive current from flowing into the circuit where the first transmitting signal is provided. Second transmission signal and start transmitting signal The light emitting thyristors LI to L60 constituting the light emitting element array 81 are arranged in the order of LI, L2,..., L59, L60 from the left side of the figure, thereby forming a light emitting element column. Further, the transfer thyristors SI to S60 are arranged in the order of SI, S2,..., S59, and S60 from the left side of the figure, thereby forming a switching element column, i.e., a switching element array 82. Also, the diodes DI to D59 are arranged in the order of DI, D2,..., D58, D59 from the left side of the figure. Further, the resistors Rl to R60 are arranged in the order of Rl, R2,..., R59, R60 from the left side of the figure.

[0088] Next, the electrical connection of each element in the light emitting chip C will be described.

[0089] The anode terminals of each of the transfer thyristors SI to S60 are connected to a GND terminal. This GND terminal is connected to a power supply line 102 (see Figure 5 ) and grounded.

[0090] The cathode terminals of the odd-numbered transfer thyristors SI, S3,..., S59 are connected to a terminal through a transfer current limiting resistor RIA. A first transfer signal line 104 (see Figure 5 ) is connected to this terminal, and a first transfer signal is supplied to this terminal.

[0091] On the other hand, the cathode terminals of the even-numbered transfer thyristors S2, S4,..., S60 are connected to a terminal through a transfer current limiting resistor R2A. A second transfer signal line 105 (see Figure 5 ) is connected to this terminal, and a second transfer signal is supplied to this terminal.

[0092] The gate terminals Gl to G60 of each of the transfer thyristors SI to S60 are connected to a Vcc terminal via the resistors Rl to R60, respectively, which are provided corresponding to each of the transfer thyristors SI to S60. This Vcc terminal is connected to a power supply line 101 (see Figure 5 ), to which a power supply voltage Vcc (-5.0 V) is supplied.

[0093] Further, the gate terminals Gl to G60 of the transfer thyristors SI to S60 are connected one-to-one to the gate terminals of the light emitting thyristors LI to L60, respectively, which have the same number.

[0094] Anodes of diodes D1 to D59 are connected to gate terminals G1 to G59 of respective transfer thyristors S1 to S59, and cathodes of these diodes D1 to D59 are connected to gate terminals G2 to G60 of adjacent next-stage transfer thyristors S2 to S60, respectively. That is, diodes D1 to D59 are connected in series in a manner sandwiching gate terminals G1 to G60 of transfer thyristors S1 to S60.

[0095] An anode of diode D1 (i.e., gate terminal G1 of transfer thyristor S1) is connected to a terminal through a transfer current limiting resistor R3A. A cathode of diode D1 is connected to a terminal. A start transfer signal line 103 (refer to ) is connected to this terminal, and a start transfer signal Figure 5 is supplied to this terminal.

[0096] Also with anodes of transfer thyristors S1 to S60, anodes of respective light emitting thyristors L1 to L60 are connected to the GND terminal.

[0097] Cathodes of light emitting thyristors L1 to L60 are connected to a terminal. A light emitting signal line 106 (in the case of light emitting chip C1, light emitting signal line 106_1: refer to ) is connected to this terminal, and a light emitting signal Figure 7 (in the case of light emitting chip C1, light emitting signal ) is supplied to this terminal. Also, respective corresponding light emitting signals are supplied to other light emitting chips C2 to C60. Note that the light emitting signal line 106 is connected to the light emitting signal line 106_1 through a light emitting current limiting resistor R6A.

[0098] <Explanation of black and white stripes generated at the switching position Kp>

[0099] In the present embodiment, as described above, the LPH stripe 631 in which the LED 71 is lit is switched in the order of LPH stripe 631a → LPH stripe 631b → LPH stripe 631c. However, at this time, since the pitch of the LED 71 changes at the switching position Kp, black or white stripes can appear in the image formed on the paper P.

[0100] Figure 7 Figs. (a) to (c) of the drawings are views showing a case where the pitch of the LED 71 changes at the switching position Kp, resulting in generation of black and white stripes on the image formed on the paper P.

[0101] wherein, Figure 7 ​​(a) shows a case where the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b are aligned in line in the sub-scanning direction at the switching position Kp, and as a result, the pitch of the respective LEDs 71 becomes a as the ideal pitch at the switching position Kp. That is, the pitch of the respective LEDs 71 of the LPH strip 631a and the pitch of the respective LEDs 71 of the LPH strip 631b are a μm. Also, the pitch between the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b at the switching position Kp is also a μm, which is the ideal pitch. That is, Figure 7 (a) shows a case where the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b are aligned in line in the sub-scanning direction at the switching position Kp, and as a result, the pitch of the respective LEDs 71 becomes a as the ideal pitch at the switching position Kp. That is, the pitch of the respective LEDs 71 of the LPH strip 631a and the pitch of the respective LEDs 71 of the LPH strip 631b are a μm. Also, the pitch between the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b at the switching position Kp is also a μm, which is the ideal pitch. That is,

[0102] On the other hand, Figure 7 (b) to (c) show a case where the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b are not aligned in line in the sub-scanning direction at the switching position Kp, but are shifted in the main scanning direction.

[0103] where, Figure 7 (b) shows a case where the pitch between the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b becomes a - β μm, which is smaller than a μm as the ideal pitch, at the switching position Kp. In this case, when switching from the LEDs 71 of the LPH strip 631a to the LEDs 71 of the LPH strip 631b at the switching position Kp, the density of the image to be formed at the switching position Kp becomes dense. As a result, a black stripe extending in the sub-scanning direction is generated in the image formed on the paper P.

[0104] On the other hand, Figure 7 (c) shows a case where the pitch between the LEDs 71 of the LPH strip 631a and the LEDs 71 of the LPH strip 631b becomes a + γ μm, which is larger than a μm as the ideal pitch, at the switching position Kp. In this case, when switching from the LEDs 71 of the LPH strip 631a to the LEDs 71 of the LPH strip 631b at the switching position Kp, the density of the image to be formed at the switching position Kp becomes sparse. As a result, a white stripe extending in the sub-scanning direction is generated in the image formed on the paper P.

[0105] The phenomena shown in (b) to (c) are generated due to the shift in the relative positions of the LPH strip 631a and the LPH strip 631b in the main scanning direction. Figure 7 That is, in the case ofFigure 7 In case (b), LPH stripe 631a and LPH stripe 631b are offset relative to each other by -βμm along the main scanning direction. Figure 8 In case (c), LPH strips 631a and 631b are offset relative to each other by +γμm along the main scanning direction. However, it is difficult to align LPH strips 631 in the main scanning direction within the micrometer specification.

[0106] Instructions on methods to suppress black and white stripes

[0107] Therefore, in this embodiment, the above-mentioned problems are suppressed by using the light-emitting chip C as described below.

[0108] Figure 9 This is a diagram illustrating the arrangement of LEDs 71 that make up the light-emitting chip C.

[0109] In the illustrated light-emitting chip C, in the central region of the LEDs 71 arranged in a column, the spacing between the LEDs 71 changes from a spacing P1 to a spacing P2 that is different from the spacing P1. Here, P1 > P2. That is, as the main scanning direction approaches, in the central region of the column of LEDs 71, the spacing changes from a wide spacing P1 to a narrow spacing P2. Here, "central region" refers to the region L / 3 of the area that enters the center when the length of the main scanning direction of the LED arrangement is set to L and divided into 3 parts. Furthermore, as the central region, it is more preferable to consider the region L / 5 of the area that enters the center when the length of the main scanning direction of the LED arrangement is set to L and divided into 5 parts.

[0110] Here, spacing P1 is an example of the first spacing, and spacing P2 is an example of the second spacing. Alternatively, it can be set to P1 > P2, but it could also be set to P1 > P2. <P2。

[0111] Figure 8 (a) is a diagram illustrating an example of the configuration of the light-emitting chip C at the connector 633.

[0112] In this embodiment, Figure 9 The light-emitting chips C shown are facing each other in opposite directions at the connector 633. Therefore, in at least a portion of the connector 633, LEDs 71 arranged at a spacing P1 and LEDs 71 arranged at a spacing P2 are facing each other.

[0113] exist Figure 8 (a) shows the following situation: making Figure 9 The light-emitting chips C shown are positioned opposite each other in reverse at the connector 633. In this case, light-emitting chips C60 and C1 are opposite each other.

[0114] Furthermore, it is preferable that the width of the light-emitting chip C facing the opposite main scanning direction is more than half the width of the arrangement of the LEDs 71 constituting the light-emitting chip C. That is, in Figure 9 In (a), the overlap width of the vertically arranged light-emitting chips C in the main scanning direction is preferably more than half the width of the LED 71 arrangement. This increases the number of LEDs 71 arranged at a spacing P1 and at a spacing P2, which will be described in detail later, and improves the resolution when determining the switching position Kp.

[0115] Figure 9 Figures (b) to (c) illustrate the width of overlap of the light-emitting chip C in the main scanning direction.

[0116] first, Figure 9 (a) shows the case where the width of the overlapping light-emitting chips C in the main scanning direction is the width L of the LED 71 arrangement. Additionally, Figure 9 (b) shows that the overlap width of the light-emitting chips C in the main scanning direction is half the width L of the LED 71 arrangement, i.e., L / 2. Furthermore, Figure 9 (c) shows the case where the overlap width of the light-emitting chips C in the main scanning direction is 1 / 3 of the width L of the LED 71 arrangement, i.e., L / 3. Therefore, Figure 9 (a) and Figure 10 Case (b) meets the above conditions. Figure 9 Case (c) is not suitable. In addition, the overlap width is preferably 75% or more of the width L of the LED 71 arrangement, and more preferably 90% or more.

[0117] Furthermore, at any location on the connector 633 where the LED 71 constituting the first light-emitting element column and the LED 71 constituting the second light-emitting element column are aligned in the sub-scanning direction, the first light-emitting element column and the second light-emitting element column are switched to emit light.

[0118] Figure 7 yes Figure 11 Enlarged view of the area surrounding the switching part Kp in (a).

[0119] In this case, the light emitting chip C60 located at the upper portion of the drawing and the light emitting chip Cl located at the lower portion of the drawing have 1024 LEDs 71 numbered 0 to 1023, respectively. In this case, the LEDs 71 of the light emitting chip C60 are the first light emitting element array. Further, the LEDs 71 of the light emitting chip Cl are the second light emitting element array. Also, a case where the respective LEDs 71 to which the number 766 is attached are aligned in the sub-scanning direction is shown. Further, since the pitch PI of the LEDs 71 of the light emitting chip C60 is different from the pitch P2 of the LEDs 71 of the light emitting chip Cl which is the second light emitting element array, the LEDs 71 before and after the LED 71 to which the number 766 is attached are offset in the sub-scanning direction. In addition, a case where the LEDs 71 to which the same number is attached are aligned in the sub-scanning direction is shown here, but a case where the LEDs 71 to which different numbers are attached are aligned in the sub-scanning direction can also be possible.

[0120] According to the above-described method, the switching site Kp is a site where the LEDs 71 of the light emitting chip C60 and the LEDs 71 of the light emitting chip Cl happen to be aligned in the sub-scanning direction. In the light emitting chip C of the present embodiment, the width in the main scanning direction in which the LEDs 71 are arranged is, for example, 10.8 mm. Also, when the resolution is set to 2400 dpi (dots per inch), 1024 LEDs 71 are arranged over this width. At this time, for example, the pitch PI is 25400 μm / 2400 = 10.6 μm. The difference between the pitch PI and the pitch P2 can be, for example, 0.01 μm. At this time, for example, the switching site Kp can be determined with a resolution of 0.1 μm to 0.2 μm. This can be achieved because the number of LEDs 71 arranged with the pitch PI and the number of LEDs 71 arranged with the pitch P2 are large with respect to each other. Therefore, even if the position of the LPH bar 631 in the main scanning direction is not strictly aligned, it is possible to make the reference position of the LPH bar 631 coincide with the switching site Kp. Figure 11 The black streaks and white streaks described above are difficult to occur.

[0121] On the contrary, in the case of the light emitting chip C in which the pitch of the LEDs 71 is changed only at the end portions, the number of LEDs 71 located at the end portions is small, and the number of LEDs 71 arranged with the pitch PI and the number of LEDs 71 arranged with the pitch P2 are small. In this case, it is necessary to increase the difference between the pitch PI and the pitch P2. Therefore, the resolution at the time of alignment is low, and it is difficult for the LEDs 71 to be aligned in the sub-scanning direction to occur. As a result, the black streaks and white streaks are easily generated.

[0122] Further, for example, when the difference in pitch is about 0.01 μm, it can be considered that the image quality of the image formed on the paper P hardly decreases. In contrast, in the case where the pitch of the light emitting chip C is changed only in the end portion, the difference in pitch becomes large, and it is easy to cause a decrease in image quality.

[0123] Figure 8 (a) to (b) of FIG. 8 are diagrams showing the configuration of the light emitting chip C.

[0124] Figure 11 (a) of FIG. 8 shows a case where the light emitting chip C shown in (a) is used only in the joint portion 633 and the light emitting chip C having a different arrangement is used in other portions. That is, the light emitting chip C of the joint portion 633 is in the central region of the LED 71 arranged in a column, and the pitch is switched from the pitch PI to the pitch P2. On the other hand, the pitch of the LED 71 arranged in a column in other portions is not changed, and is all the pitch PI. In this case, it can be said that the light emitting chip C is arranged in the joint portion 633, but is not arranged in other positions. Figure 11

[0125] Figure 8 (b) of FIG. 8 shows a case where the light emitting chip C is used not only in the joint portion 633 but also in other regions. In this case, it can be said that the light emitting chip C is used not only in the joint portion 633 but also in all regions in the main scanning direction, and the first light emitting element column and the second light emitting element column are constituted by the same kind of light emitting chip C.

[0126] The problem of the black stripe and the white stripe is a phenomenon generated in the joint portion 633, and thus in order to suppress this phenomenon, as shown in (a) of FIG. 8, it is sufficient to use the light emitting chip C shown in (a) only in the joint portion 633. However, in this case, it is necessary to prepare two kinds of light emitting chip C. Figure 11 Figure 12 In contrast, in the case of (b) of FIG. 8, there is an advantage that it is sufficient to prepare only one kind of light emitting chip C.

[0127] In contrast, in the case of (b) of FIG. 8, there is an advantage that it is sufficient to prepare only one kind of light emitting chip C. Figure 13 According to the above-described mode, it is possible to provide the light emitting element head 14 and the image forming apparatus 1 in which the black stripe and the white stripe are less likely to be generated in the image formed on the paper P at the switching position Kp.

[0128] In the above-described example, the correction of the density difference in the joint portion 633 between the LPH bars 631 is explained. However, the present application can also be applied to suppression of the black stripe and the white stripe generated between the light emitting chips C due to the positional shift of the light emitting chip C.

[0129]

[0130] ​​​In addition, in the above-described example, the light emitting element head 14 provided to the image forming apparatus 1 is described as the light emitting apparatus, but is not limited thereto.

[0131] ​ Fig. 10 is a view showing another example of the light emitting apparatus.

[0132] The illustrated light emitting apparatus shows an exposure head 310 that exposes a planar exposure surface. The exposure head 310 is provided to an exposure apparatus 300.

[0133] The exposure apparatus 300 is used, for example, for exposure of a dry film resist (DFR) in a manufacturing process of a printed wiring board (PWB), formation of a color filter in a manufacturing process of a liquid crystal display (LCD), exposure of a DFR in a manufacturing process of a thin film transistor (TFT), and exposure of a DFR in a manufacturing process of a plasma display panel (PDP).

[0134] The exposure apparatus 300 has, in addition to the exposure head 310, an exposure stage 320 that places a substrate 350 and a moving mechanism 330 that moves the exposure head 310.

[0135] The exposure head 310 has the same structure as the above-described light emitting element head 14. That is, it has a light emitting portion 63 that has a plurality of LEDs 71, a circuit substrate 62 on which the light emitting portion 63 and a signal generating circuit 100 and the like are mounted, and a rod lens array 64 that images light output from the LEDs. The light emitting portion 63 includes an LPH bar 631, a focus adjustment pin 632, and the signal generating circuit 100.

[0136] The exposure stage 320 is a stage that places the substrate 350 that is an object of exposure. The substrate 350 carries the above-described DFR and is subjected to exposure.

[0137] As shown in the drawing, the moving mechanism 330 reciprocally moves the exposure head 310 in the double arrow direction R1 along the sub-scanning direction. Thereby, the exposure head 310 is scanned in the main scanning direction and is moved in the sub-scanning direction, and thus the DFR and the like are exposed.

[0138] In addition, here, the exposure head 310 is moved, but exposure can also be performed by moving the exposure stage 320 in the sub-scanning direction.

[0139] ​ Fig. 11 is a view showing still another example of the light emitting apparatus.

[0140] The illustrated light emitting device is a view showing an exposure head 410 that exposes a curved exposure surface. The exposure head 410 is provided in an image recording device 400.

[0141] The image recording device 400 is, for example, a CTP (Computer to Plate) output device that directly performs image recording on a recording material.

[0142] The image recording device 400 includes, in addition to the exposure head 410, a rotary drum 420 that holds a recording material 450, a moving mechanism 430 that moves the exposure head 410, and a rotating mechanism 440 that rotates the rotary drum 420.

[0143] The exposure head 410 has the same structure as the light emitting element head 14 described above.

[0144] The rotary drum 420 rotates the recording material 450 by rotating itself.

[0145] The moving mechanism 430 reciprocally moves the exposure head 410 in the double arrow direction R2 along the main scanning direction, thereby performing scanning in the main scanning direction. The moving mechanism 430 is, for example, a linear motor.

[0146] In addition, the rotating mechanism 440 rotates the rotary drum 420, thereby moving the recording material 450 in the sub scanning direction and exposing the recording material 450.

[0147] Here, the exposure head 410 is one, but a plurality of exposure heads 410 can be provided to share the operation in the main scanning direction.

[0148] Further, with respect to the present embodiment, various application examples such as direct drawing on a printed board and the like can be considered.

[0149] For example, the light emitting element head 14 of the present embodiment can be used as a flat bottom type exposure device that has a flat plate-shaped stage that adsorbs and holds a sheet-shaped recording material or photosensitive material (for example, a printed board) on a surface, or can be a so-called outer drum type exposure device that has a drum that winds a recording material or photosensitive material (for example, a flexible printed board). The light emitting element head 14 described above can be applied to a device that is positioned in the axis direction (sub scanning direction) of a rotary drum that holds a photosensitive material and is capable of rotating in the circumferential direction (main scanning direction) by the rotary drum being rotated around the axis by a driving mechanism. In this way, the light emitting element head 14 can be used as an exposure device of a CTP (Computer To Plate) that directly exposes a version material.

[0150] The light emitting element head 14 described above can be preferably used for exposure of a dry film resist (DFR) in a manufacturing process of a printed wiring board (PWB), formation of a color filter in a manufacturing process of a liquid crystal display device (LCD), exposure of a DFR in a manufacturing process of a TFT, exposure of a DFR in a manufacturing process of a plasma display panel (PDP), and the like.

[0151] In addition, in the light emitting element head 14 described above, either of a photonic mode photosensitive material that directly records information by exposure or a thermal mode photosensitive material that records information by heat generated by exposure can be used. In the case of using the photonic mode photosensitive material, a GaN-based semiconductor laser, a wavelength conversion solid laser, or the like is used in a laser device, and in the case of using the thermal mode photosensitive material, an AlGaAs-based semiconductor laser (infrared laser), a solid laser is used in a laser device.

[0152] In addition, the image forming apparatus 1 as a whole can be a light emitting device.

[0153] Although the present embodiment has been described, the technical scope of the present disclosure is not limited to the scope described in the above-described embodiment. It is apparent that a scope still falls within the scope of the present disclosure, by various modifications or improvements of the above-described embodiment. The scope of the claims is intended to cover the modifications and improvements of this scope.

Claims

1. A light emitting device, comprising: The light emitting device has: a first light emitting element column constituted by light emitting elements arranged in a column in a main scanning direction; and a second light emitting element column constituted by light emitting elements arranged in a column in the main scanning direction, at least a part of which overlaps the first light emitting element column in a sub-scanning direction, the first light emitting element column and the second light emitting element column being constituted by arranging light emitting element array chips in which light emitting elements are arranged in a column in the main scanning direction, in a central region of the light emitting elements arranged in a column, the pitch between the light emitting elements is switched from a first pitch to a second pitch different from the first pitch, in at least a part of an overlapping portion where the first light emitting element column and the second light emitting element column overlap, the light emitting elements arranged at the first pitch and the light emitting elements arranged at the second pitch are opposed to each other, in the overlapping portion, the light emitting element array chips having the same arrangement of light emitting elements are opposed to each other in a direction opposite to each other, and the width of the light emitting element array chips in the main scanning direction in which the light emitting elements arranged at the first pitch and the light emitting elements arranged at the second pitch are opposed to each other is more than half of the arrangement width of the light emitting elements constituting the light emitting element array chips.

2. The light emitting device of claim 1, wherein, In a portion where the light emitting elements constituting the first light emitting element column and the light emitting elements constituting the second light emitting element column are aligned in the sub-scanning direction at an arbitrary portion of the overlapping portion, the first light emitting element column and the second light emitting element column are switched to emit light.

3. The light emitting device of claim 1, wherein, The light emitting element array chip is arranged in the overlapping portion where the first light emitting element column and the second light emitting element column overlap.

4. The light emitting device of claim 3, wherein, The light emitting element array chip is used not only in the overlapping portion but also in all regions in the main scanning direction, and the first light emitting element column and the second light emitting element column are constituted by the same kind of light emitting element array chip.

5. The light emitting device according to claim 1, wherein A toner image is formed from an electrostatic latent image formed by light emission, and the light emitting device further has: a transfer unit that transfers the toner image onto a recording medium; a fixing unit that fixes the toner image transferred onto the recording medium to form an image; and a switching unit that switches the first light emitting element column and the second light emitting element column to emit light in a switching portion provided at an arbitrary portion of the overlapping portion where the first light emitting element column and the second light emitting element column overlap.

6. An exposure device having: the light emitting device according to any one of claims 1 to 4; and an optical element for imaging the light output of the light emitting elements to expose a photoreceptor to form an electrostatic latent image. ​

Images