Light-emitting device and image formation device with the light-emitting device

Abstract

To provide a light-emitting device that suppresses light quantity loss caused by a lens, and an image formation device with the light-emitting device.SOLUTION: A light-emitting device comprises: an image processing device that divides an input image in a first direction to generate a plurality of divided images and then performs image processing on the plurality of divided images respectively to generate a plurality of division images from the plurality of divided images respectively; a light-emitting element array which comprises a plurality of light-emitting element groups emitting light corresponding to the plurality of divided images respectively, each of the plurality of light-emitting element groups comprising two or more light-emitting elements; and a lens array which is arrayed along a first direction, and comprises a plurality of graded refractive index lenses having a plurality of incidence ends that light corresponding to the plurality of division images impinges on respectively and also comprises a plurality of emission ends emitting light forming an output image on an image-formed surface, wherein the plurality of graded refractive index lenses have a length smaller than a length of one pitch.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a light emitting device and an image forming apparatus including the light emitting device. [Background technology]

[0002] Generally, electrophotographic image forming apparatuses are equipped with a light-emitting device that uses a light-emitting element as a light source, and the light-emitting device forms an image on the surface of a photoconductor and exposes the surface of the photoconductor to form an electrostatic latent image. Charged toner is transported to a developing roller, which then supplies it to the surface of the photoconductor to develop the electrostatic latent image. The developed toner image is transferred to paper, and the toner image is fixed to the paper by a fixing device.

[0003] The light emitting device described above includes a lens for forming an image of the light emitted from the light emitting element on the surface of the photoconductor, which is the imaged surface. For example, Patent Document 1 shows an LED print head having a light emitting element array in which light emitting elements such as light emitting diodes (hereinafter, LEDs) are arranged, and a rod lens array in which a plurality of rod lenses are arranged. The light emitted from the plurality of light emitting elements is collected by the rod lens and formed into an image on the photoconductor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-166448 A Summary of the Invention [Problem to be solved by the invention]

[0005] According to Patent Document 1, the rod lens is a rod-shaped lens that forms an erect life-size image, and for example, a gradient index rod lens is used. The light emitted from the light emitting element and incident on one end of the rod lens is lost due to the influence of Rayleigh scattering loss and absorption loss while propagating to the other end of the rod lens while meandering inside the rod lens. For example, if the amount of light incident on one end of the rod lens is 100, the amount of light emitted from the other end of the rod lens may decrease to about 10.

[0006] In order to compensate for the light loss caused by the rod lens and perform exposure, it is necessary to increase the amount of light emitted by the light-emitting element. However, in order to increase the amount of light, it is necessary to increase the power supplied to the light-emitting element, which increases power consumption. Furthermore, when the light-emitting element is an organic light-emitting diode that uses an organic electroluminescence element (hereinafter referred to as an organic EL element), increasing the supply power to increase the amount of light may shorten the life of the element.

[0007] In view of the above problems, an object of the present disclosure is to provide a light-emitting device that suppresses loss of light quantity due to lenses, and an image forming apparatus including the light-emitting device. [Means for solving the problem]

[0008] A light emitting device according to one embodiment of the present disclosure comprises an image processing device that divides an input image in a first direction to generate a plurality of divided images and performs image processing on each of the plurality of divided images to generate a plurality of segment images from the plurality of divided images, respectively; a light emitting device array having a plurality of light emitting element groups that emit light corresponding to the plurality of segment images, each of the plurality of light emitting element groups having two or more light emitting elements; and a lens array having a plurality of refractive index gradient lenses arranged along the first direction, each of which has a plurality of incident ends into which light corresponding to the plurality of segment images is incident and a plurality of exit ends that emit light that forms an output image on an imaged surface, wherein the length of the plurality of refractive index gradient lenses is shorter than the length of one pitch. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an internal structure of an image forming apparatus according to the present disclosure. [Diagram 2] 2 is a schematic diagram showing the peripheral portion of the light emitting device of FIG. 1 according to the present disclosure. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 2 is a block diagram of a control device and a light emitting device according to the present disclosure. [Diagram 5] FIG. 2 is a schematic diagram illustrating a process from image processing to image formation in the first embodiment. [Figure 6] FIG. 11 is a schematic diagram showing a process from image processing to image formation in a modified example of the image processing of the first embodiment. [Figure 7] FIG. 11 is a schematic diagram illustrating a process from image processing to image formation in the second embodiment. [Figure 8] 11 is a flowchart relating to image processing according to the second embodiment. [Figure 9] FIG. 11 is a schematic diagram showing a process from image processing to image formation in a modified example of image processing according to the second embodiment. [Figure 10] FIG. 11 is a schematic diagram illustrating a process from image processing to image formation in the third embodiment. [Figure 11] FIG. 13 is a schematic diagram illustrating a process from image processing to image formation in the fourth embodiment. [Figure 12] FIG. 13 is a schematic diagram relating to image processing according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, in the drawings, the same or similar elements are given the same reference numerals, and duplicated explanations are omitted. In addition, the embodiments described below do not unduly limit the contents of the present disclosure described in the claims, and all of the configurations described in the embodiments are not necessarily essential as a solution to the present disclosure.

[0011] <Image forming device> 1 is a schematic cross-sectional view showing the internal structure of an image forming apparatus 100 according to the present disclosure. The image forming apparatus 100 is, for example, a multifunction machine having a copying function, a printer function, a scanner function, a facsimile function, etc., and forms a multicolor or monochrome image on a printing paper by an electrophotographic method. Note that the image forming apparatus 100 according to the present disclosure is not limited to a multifunction machine, and may be, for example, a printing machine having only a printer function.

[0012] The image forming apparatus 100 includes, for example, a main body 101 and an image reading device 102 disposed above the main body 101. The image reading device 102 includes a document feeder that automatically feeds documents one by one, and an image reading unit that reads images of the documents, and generates image data based on the images of the documents read by the image reading unit.

[0013] The main body 101 includes a control device 400, a toner cartridge 106, a photoconductor 201 having an image forming surface 202, a light emitting device 300, a developing device 203, a transfer unit 204, another light emitting device 300, an automatic paper feed tray 103, a manual paper feed tray 104, a paper discharge tray 105, and the like.

[0014] The control device 400 is a device that controls the image forming apparatus 100. The control device 400 is composed of one or more microcontrollers and peripheral circuits. The microcontroller includes a processor and a memory. The processor executes a control program stored in the memory to operate the microcontroller and the peripheral circuits as the control device 400. All or part of the processing performed by the microcontroller may be performed by a dedicated electronic circuit.

[0015] The control device 400 further includes a communication unit and the like that receives data, signals, and the like from the outside. The control device 400 transmits various data, control signals, and the like to each device included in the image forming apparatus 100 in response to an input operation by a user, data reception from the outside, and the like, and causes the image forming apparatus 100 to execute various operations. As will be described in detail later, the control device 400 includes an image processing device 401 and the like that processes image data received from the outside before transmitting it to the light-emitting device 300.

[0016] The photoconductor 201 has a cylindrical conductive base body, and an image based on image data is formed on the image-forming surface 202, which is the outer surface of the base body. The image-forming surface 202 is charged to a predetermined potential by a charger (not shown). The photoconductor 201 has a rotating shaft (not shown) that runs along the axis, and is rotated around the rotating shaft by an electric motor (not shown).

[0017] The light-emitting device 300 irradiates the image-forming surface 202 with light for exposing the photoconductor 201. As will be described in detail later, the light-emitting device 300 irradiates the image-forming surface 202 with light that forms an image corresponding to image data based on image data that has been image-processed by an image processing device 401 included in the control device 400. The charged image-forming surface 202 is exposed to the light irradiated by the light-emitting device 300, and an electrostatic latent image corresponding to the image data is formed on the image-forming surface 202.

[0018] The developing device 203 includes a developing tank that contains the toner supplied from the toner cartridge 106, a developing roller attached to the developing tank, etc. The developing device 203 supplies toner to the surface of the photoconductor 201 via the developing roller that is rotated by an electric motor (not shown), and develops the electrostatic latent image on the imaging surface 202 to form a toner image.

[0019] This disclosure illustrates an image forming apparatus 100 capable of printing full-color images, which realizes full-color image printing by superimposing monochromatic images corresponding to each of the four colors of cyan, magenta, yellow, and black. Thus, the image forming apparatus 100 includes four toner cartridges 106 containing toner of each of the four colors, and four photoconductors 201, four light-emitting devices 300, and four developing devices 203 corresponding to each of the four colors. For example, each of the four photoconductors 201, the four light-emitting devices 300, and the four developing devices 203 has the same structure, and only the color of the toner supplied from the toner cartridges 106 to the developing devices 203 is different. Although not illustrated in this disclosure, an image forming apparatus capable of printing monochrome images is composed of only a toner cartridge, photoconductor, light-emitting device, and developing device corresponding to black, unlike a full-color image.

[0020] Transfer unit 204 is disposed above the four photoconductors 201, and includes four primary transfer rollers 205 corresponding to the four photoconductors 201, a transfer belt 206 driven by a drive roller (not shown), and a secondary transfer roller 207. Primary transfer roller 205, the drive roller, and secondary transfer roller 207 are rotated by an electric motor (not shown).

[0021] When a current is supplied to the primary transfer roller 205, a transfer electric field is formed between the photoconductor 201 and the transfer belt 206 at the position of the primary transfer roller 205. The action of the transfer electric field causes the toner image developed on the imaging surface 202 to be transferred onto the transfer belt 206. Toner images corresponding to each of the four colors, cyan, magenta, yellow, and black, are sequentially transferred and superimposed onto the transfer belt 206 by each of the multiple primary transfer rollers 205, and a full-color toner image is formed on the transfer belt 206.

[0022] The secondary transfer roller 207 is a member that transfers a toner image onto the print paper, and faces the transfer belt 206. The print paper supplied from the automatic paper feed tray 103 or the manual paper feed tray 104 is transported by a plurality of transport rollers and passes between the secondary transfer roller 207 and the transfer belt 206. When the print paper passes between the secondary transfer roller 207 and the transfer belt 206, the toner image formed on the transfer belt 206 is transferred onto the print paper. The toner image transferred onto the print paper is heated and pressed by a heating roller, a pressure roller, etc. (not shown) to be fixed onto the print paper. As described above, the image forming apparatus 100 completes printing of an image onto the print paper based on the received image data. The print paper on which printing has been completed is discharged to the paper discharge tray 105.

[0023] <Light emitting device> Fig. 2 is a schematic diagram showing the peripheral portion of the light-emitting device 300 of Fig. 1 according to the present disclosure. The left-right direction of Fig. 2 corresponds to the front-to-back direction of Fig. 1, and for simplicity, one photoconductor 201 and one light-emitting device 300 are selectively illustrated.

[0024] The light emitting device 300 includes a lens array 310 including a plurality of gradient index lenses (also called GRIN lenses) 311. The light emitting device 300 is fixed below the photoconductor 201 with a certain distance therebetween.

[0025] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. The light emitting device 300 has a light emitting element array 301 disposed on the lower side, and a lens array 310 disposed on the upper side.

[0026] The light emitting element array 301 is provided on a light emitting element array substrate 304 and includes a plurality of light emitting element groups 302 arranged along a first direction. Each of the plurality of light emitting element groups 302 includes two or more light emitting elements 303. The light emitting element array substrate 304 is fixed to a light emitting element array housing 305, and light is emitted upward from the light emitting element 303. Each of the plurality of light emitting elements 303 is, for example, an organic light emitting diode, an inorganic light emitting diode, or the like. Although not shown in FIG. 3, a light emitting element driver 306, which will be described later, is provided on the light emitting element array substrate 304. The light emitting element driver 306 divides image data processed by the image processing device 401 into a plurality of line shapes, and controls the light emission of the light emitting element array 301 so as to sequentially display the divided image data line by line.

[0027] Lens array 310 is attached to lens array housing 314 and includes a plurality of gradient index lenses 311 arranged along a first direction. As can be seen from Figures 2 and 3, gradient index lens 311 is a cylindrical rod-shaped lens, and has an entrance end 312 where light from light emitting element group 302 enters gradient index lens 311, and an exit end 313 where light exits gradient index lens 311. As described above, light emitting element array 301 and lens array 310 correspond to the display of one line of image data divided into a plurality of line shapes.

[0028] 2 and 3, light emitted from light-emitting element array 301 passes through lens array 310, exits from the upper surface of light-emitting device 300, and reaches image-formed surface 202, which is the surface of photoconductor 201. Note that, in FIG. 2, lens array 310 illustrates a structure in which two rows of gradient index lenses 311 are arranged in a second direction intersecting at a right angle with the first direction, but in the present disclosure, the number of rows of gradient index lenses 311 arranged can be determined arbitrarily, and may be one row or three or more rows. For simplicity, the following description will be given on the premise that there is one row of gradient index lenses 311 in the second direction.

[0029] The gradient index lens 311 is, for example, a cylindrical glass rod shape, and is formed so that the refractive index of light is maximum at its central axis and decreases parabolically toward the outer periphery. As a result, light incident from the entrance end 312 progresses inside the gradient index lens 311 while meandering in a sinusoidal wave with a constant period, and is emitted from the exit end 313.

[0030] The meandering periodic length of light passing through the gradient index lens 311 is called the pitch. The pitch is determined by the refractive index, refractive index distribution, etc. of the gradient index lens 311. When the lens length, which is the length of the central axis of the gradient index lens 311, is the same length as the pitch (one pitch), the original image formed by the light incident from the incident end 312 is imaged on the imaged surface 202 as an erect image of the same size and direction as the original image when it is emitted from the exit end 313.

[0031] 3, the lens length L of the gradient index lens 311 of the present disclosure is the length of the central axis of the gradient index lens 311, in other words, the length from the incident end 312 to the exit end 313. The multiple gradient index lenses 311 included in the lens array 310 all have the same lens length L.

[0032] In the present disclosure, the lens length L is set to be shorter than one pitch of the gradient index lens 311. This shortens the optical path length through which the incident light passes inside the gradient index lens 311, making it possible to suppress loss of the amount of light caused by the gradient index lens 311. Therefore, according to the present disclosure, when the amount of light emitted from the emission end 313 is the same, the amount of light from the light emitting element 303 can be reduced compared to when the lens length is one pitch, thereby realizing reduced power consumption and a longer life for the light emitting element 303.

[0033] However, when the lens length L is shorter than one pitch, the original image formed by the light incident from the entrance end 312 is formed on the imaged surface 202 as an image inverted in at least a first direction when it is emitted from the exit end 313. In the present disclosure, in a configuration in which the lens length L of the refractive index distribution lens 311 is shorter than one pitch, image data incident as a light image from the light-emitting element array 301 is inverted in the first direction in advance by image processing described later, so that when the light image is emitted from the exit end 313, an erect image of the same size and orientation as the original image is formed on the imaged surface 202.

[0034] <Control device> 4 is a block diagram of a control device 400 and a light emitting device 300 according to the present disclosure. The control device 400 includes an image processing device 401, an image input unit 402, an image correction unit 403, an input image storage unit 404, an image processing parameter storage unit 405, and an image output unit 406. The light emitting device 300 includes a light emitting element driver 306 and a light emitting element 303.

[0035] The image input unit 402 is a unit that receives image data transmitted from the outside. The image data as the input image is, for example, image data read by the image reading device 102, image data transmitted from the outside as an electronic file, etc. The image input unit 402 transmits the received image data to the image correction unit 403.

[0036] Image correction unit 403 is a part that corrects image data into a format corresponding to printing by image forming apparatus 100, and performs processing such as converting image data based on the three primary colors of light, red, blue, and green, into image data based on the four colors, cyan, magenta, yellow, and black, used in printing, and dividing the image data into four images corresponding respectively to the four colors, cyan, magenta, yellow, and black. The image data processed by image correction unit 403 is transmitted to input image storage unit 404.

[0037] The input image storage unit 404 is a line memory that divides the image data transmitted from the image correction unit 403 into a plurality of line shapes along a first direction and stores the divided image data. The input image storage unit 404 transmits the image data to the image processing device 401 line by line.

[0038] The image processing device 401 performs image processing (to be described later) on one line of image data transmitted from the input image storage unit 404 based on various parameters stored in the image processing parameter storage unit 405. The image processing device 401 transmits the image-processed image data to the image output unit 406. The image output unit 406 transmits the image-processed one line of image data to the light-emitting element driver 306 of the light-emitting device 300.

[0039] The light emitting element driver 306 controls the light emitting element groups 302 included in the light emitting element array 301 so as to emit light according to the transmitted image data of one line. Specifically, the light emitting element array 301 outputs an image of the transmitted image data of one line as light.

[0040] 4 illustrates a configuration in which the control device 400 includes an image processing device 401, an image input unit 402, an image correction unit 403, an input image storage unit 404, an image processing parameter storage unit 405, and an image output unit 406, but this illustrates a part of the control device 400, and excerpts include a configuration for image processing image data and a part for transmitting the image-processed image data to the light-emitting device 300. The present disclosure is not limited to the above-mentioned configuration, and for example, the light-emitting device 300 may include the image processing device 401, the image input unit 402, the image correction unit 403, the input image storage unit 404, the image processing parameter storage unit 405, and the image output unit 406 inside, instead of the control device 400. Furthermore, even if the image processing device 401, image input unit 402, image correction unit 403, input image memory unit 404, image processing parameter memory unit 405, and image output unit 406 are physically provided inside the control device 400, they can also be considered to be an integral configuration with the light-emitting device 300.

[0041] <Embodiment 1> Hereinafter, the first embodiment of the present disclosure will be described with reference to Figs. 4 and 5. Fig. 5 is a schematic diagram of the process from image processing to image formation in the first embodiment of the present disclosure. In the first embodiment, the lens length L1 of the gradient index lens 311 is 1 / 2 pitch (0.5 pitch). When the lens length L1 of the gradient index lens 311 is 1 / 2 pitch, the original image formed by the light incident from the incident end 312 is imaged on the imaged surface 202 as an image of the same size as the original image and inverted in the first direction when it is emitted from the emission end 313. For simplicity, Fig. 5 illustrates a configuration in which the lens array 310 includes three gradient index lenses 311.

[0042] 4, an image processing device 401 transmits image data input from an external device to an image input unit 402 to an input image storage unit 404 via an image correction unit 403. The input image storage unit 404 divides the transmitted image data into a plurality of line shapes along a first direction, and stores the divided image data as an input image 500 for each line, as shown in FIG.

[0043] The image processing device 401 divides the input image 500 transmitted from the input image storage unit 404 in a first direction based on the parameters stored in the image processing parameter storage unit 405 to generate a plurality of divided images 600. Here, the above-mentioned parameters include the size of the first width W of one divided image, etc. For example, in FIG. 5, the first width W of one divided image 600 corresponds to the width of an image that can be displayed in the light emission region of the light-emitting element group 302 that can be received by the incident end 312 of one gradient index lens 311. FIG. 5 illustrates a configuration in which the incident end 312 of one gradient index lens 311 can receive the light of the light emission region of one light-emitting element group 302.

[0044] Next, the image processing device 401 performs image processing on each of the multiple divided images 600, and generates multiple segmented images 700 from the multiple divided images 600. In the first embodiment, the multiple divided images 700 are inverted in a first direction to generate the multiple segmented images 700. In other words, in FIG. 5, the multiple divided images 700 are inverted left and right to generate the multiple segmented images 700. In this case, the parameters stored in the image processing parameter storage unit 405 include a process for inverting the divided image 600 left and right.

[0045] Next, the image processing device 401 transmits the plurality of segmented images 700 as one line of image data to the image output unit 406. The image output unit 406 outputs the plurality of segmented images 700 to the light emitting element driver 306 of the light emitting device 300.

[0046] The light-emitting element driver 306 controls the multiple light-emitting element groups 302 included in the light-emitting element array 301 so as to emit light corresponding to multiple segmented images 700. For simplicity, Fig. 5 illustrates a configuration in which one light-emitting element group 302 emits light corresponding to one segmented image 700, but the number of corresponding light-emitting element groups can be determined arbitrarily.

[0047] Light corresponding to the plurality of segmented images 700 emitted by the light emitting element array 301 enters the lens array 310. As shown in FIG. 5, the light corresponding to one segmented image 700 is set to enter one gradient index lens 311. At this time, the incident light passes through the gradient index lens 311, and when it is emitted from the emission end 313, it is formed as an image having the same size as the original image and inverted in the first direction. As described above, since the segmented image 700 is inverted in the first direction in advance by the image processing device 401, the image formed on the image-formed surface 202 is an erect image of the same size and orientation as the original image, with the segmented image 700 further inverted. All of the plurality of segmented images 700 are formed on the image-formed surface 202 as erect images of the same size and orientation as the original image, and an output image 800, which is the same image as the original input image 500, is finally formed. In this way, in embodiment 1, even if a gradient index lens 311 with a lens length L1 of 1 / 2 pitch, which is shorter than 1 pitch, is used in the light emitting device 300, the image data received by the image forming device 100 can be printed in the same orientation and the same size.

[0048] In the light emitting device 300 of the first embodiment, the lens length L1 of the gradient index lens 311 is 1 / 2 pitch, so that the loss of the light amount due to the gradient index lens 311 is half that in the case where the lens length is 1 pitch. For example, in the case where the loss is 90% in the case where the lens length is 1 pitch, the loss rate can be reduced to 45% in the first embodiment. As a result, in the first embodiment, even if the light amount of the light emitting element 303 is reduced by about 45%, the light amount at the imaged surface 202 can be made the same as that in the case where the lens length is 1 pitch, and it is possible to realize a reduction in power consumption and a longer life of the light emitting element 303.

[0049] The present disclosure is particularly useful when an organic light-emitting diode is used as the light-emitting element 303. The light amount of an inorganic light-emitting diode that is generally used as the light-emitting element 303 of the light-emitting device 300 of the image forming apparatus 100 is about 700 nW, whereas the light amount of an organic light-emitting diode is small, about 80 nW. In order to expose a general photoconductor 201, it is necessary to irradiate the image-formed surface 202 with a light amount of about 40 nW, so that the exposure may be incomplete due to the loss of light caused by the gradient index lens 311. In addition, if the applied power is increased to increase the light amount of the organic light-emitting diode, the life of the organic light-emitting diode will be shortened. In the present disclosure, the loss of light caused by the gradient index lens 311 is reduced, so that it is easy to ensure the amount of light that can be exposed even if an organic light-emitting diode is used as the light-emitting element 303.

[0050] <Modification of the first embodiment> 6 is a schematic diagram of the process from image processing to image formation in a modification of the image processing of embodiment 1. The modification of embodiment 1 differs in that the image processing further includes a process of inverting each of the multiple divided images 600 in a second direction perpendicular to the first direction.

[0051] Specifically, as shown in Fig. 6, the image processing device 401 performs image processing on each of the multiple divided images 600 by flipping the multiple segmented images 700 in a first direction and then flipping them in a second direction perpendicular to the first direction to generate the multiple segmented images 700. In other words, in Fig. 6, the multiple segmented images 700 are flipped vertically and horizontally to generate the multiple segmented images 700. In this case, the parameters stored in the image processing parameter storage unit 405 include both a process of flipping the divided images 600 horizontally and a process of flipping the divided images 600 vertically.

[0052] Depending on conditions such as the physical characteristics of the gradient index lens 311 and the positional relationship between the gradient index lens 311 and the light emitting element group 302, when the lens length is shorter than one pitch, an original image formed by light incident from the incident end 312 may be formed on the imaged surface 202 as an image that is inverted in both the first and second directions when emitted from the emission end 313. Even in such a case, this modified example can print the image data received by the image forming apparatus 100 in the same orientation and with the same size, as shown in FIG.

[0053] <Embodiment 2> 7 is a schematic diagram from image processing to image formation in embodiment 2. This embodiment differs from embodiment 1 in that the lens length L2, which is the length of each of the multiple gradient index lenses 311, is 1 / 4 pitch (0.25 pitch).

[0054] When the lens length L2 is 1 / 4 pitch, an image formed by light incident from the entrance end 312 is magnified in the first direction compared to the original image when it is emitted from the exit end 313, and is formed on the imaged surface 202 as an image inverted in the first direction. The magnification is determined in advance as a predetermined magnification depending on the dimensions, shape, refractive index, and refractive index distribution of the refractive index gradient lens 311, the positional relationship between the refractive index gradient lens 311 and the light emitting element group 302, and the like.

[0055] In the second embodiment, as shown in FIG. 7, the image processing device 401 performs image processing on each of the multiple divided images 600 by inverting each of the multiple divided images 600 in a first direction and further reducing the divided images in the first direction. In FIG. 7, the second width X of the divided image 700 is made smaller than the first width W of the divided image 600. In this case, the parameters stored in the image processing parameter storage unit 405 include a reduction ratio, which is a ratio by which the divided image 600 is reduced. The reduction ratio is the reciprocal of a predetermined enlargement ratio. As a result, when the divided image 700 passes through the gradient index lens 311, it is inverted in the first direction and enlarged by a predetermined enlargement ratio to return to the first width W that is the same as the divided image 600. Therefore, the image formed on the image-formed surface 202 is an erect image having the same orientation and size as the original image.

[0056] In the light emitting device 300 of the second embodiment, the lens length L1 of the gradient index lens 311 is 1 / 4 pitch, so that the loss of the light amount due to the gradient index lens 311 is 1 / 4 of that when the lens length is 1 pitch. For example, when the loss is 90% when the lens length is 1 pitch, the loss rate can be reduced to 22.5% in the first embodiment. As a result, even if the light amount of the light emitting element 303 is reduced by about 68%, the light amount at the imaged surface 202 can be made the same as when the lens length is 1 pitch in the second embodiment, and further reduction in power consumption and extension of the life of the light emitting element 303 can be realized.

[0057] By appropriately changing the reduction ratio of the image, it is possible to employ the configuration of the second embodiment even when the lens length L2 is different from 1 / 4 pitch.

[0058] Fig. 8 is a flowchart showing an example of the flow of image processing according to the second embodiment, which is performed by the control device 400. The following will be described with reference to Figs. 4, 7, 8, etc.

[0059] The input image storage unit 404 divides the transmitted image data into a plurality of line shapes along the first direction and stores each line as an input image 500. At this time, the input image storage unit 404 counts and stores the total number of lines per page, which is the number of divisions of the image data. The image processing device 401 counts the number of received input images 500 as a line counter h. The line counter h is an arbitrary integer equal to or greater than 0, and the maximum value thereof coincides with the total number of lines per page. In step S1 of FIG. 8, the image processing device 401 inputs zero into the line counter h to initialize it.

[0060] The image processing device 401 counts the number of gradient index lenses 311 included in the lens array 310 along the first direction from one end to the other end of the lens array 310 as a lens counter n. The lens counter n is an arbitrary integer equal to or greater than 0, and the maximum value thereof matches the total number of gradient index lenses 311 included in the lens array 310. In step S2 of Fig. 8, the image processing device 401 inputs zero into the lens counter n to initialize it.

[0061] The input image storage unit 404 is, for example, a line memory, and stores the input image 500 in a register memory arranged in a line corresponding to the first direction. In step S3 of FIG. 8, the image processing device 401 reads out a predetermined range in the first direction of the input image 500 stored in the input image storage unit 404 as a divided image 600. The range in which one divided image 600 is read out is determined by the range of the input image 500 that one gradient index lens 311 can receive. The range in which one gradient index lens 311 can receive light is set in the range between the lens boundary start position register ST(n) and the lens boundary start position register ED(n), which indicate coordinates on the input image 500 in the first direction. The coordinates of each of the lens boundary start position register ST(n) and the lens boundary start position register ED(n) are previously determined to a predetermined value according to the characteristics of the gradient index lens 311, and are previously stored in the image processing parameter storage unit 405. Hereinafter, the lens boundary start position register is also simply referred to as a register. In FIG. 7, the initial value of register ST(0) is one end on the left side in the first direction of the input image 500, and the coordinate is zero, which is the origin.

[0062] 8, the image processing device 401 sets the read position of the input image storage unit 404 to register ST(0), and reads out the input image 500 within a range of a first width W from the register ST(0) in the first direction as one divided image 600. The first width W is a fixed length that is arbitrarily set in advance as a width for the image processing device 401 to read out one divided image 600, and is stored in advance in the image processing parameter storage unit 405.

[0063] In step S5 in Fig. 8, the image processing device 401 performs image processing on the read divided image 600 based on the parameters stored in the image processing parameter storage unit 405 to generate a sectioned image 700. As shown in Fig. 7, the image processing performed in the second embodiment is a process of inverting the divided image 600 in a first direction, and further reducing it in the first direction to a second width X smaller than the first width W.

[0064] 8, the image processing device 401 outputs the generated segmented image 700 to the image output unit 406. Although not shown, the image output unit 406 has a line memory that sequentially stores a plurality of segmented images 700, similar to the input image storage unit 404.

[0065] 8, the image processing device 401 increments +W the coordinates of the read position where the input image is read from the input image storage unit 404. In other words, the next read position is set to the coordinates on the input image 500 that are shifted in the first direction by the same amount as the first width W from the register ST(0), which is the initial read position of the input image storage unit 404.

[0066] 8, if the next read position in the input image storage unit 404 is smaller than the coordinates of the register ED(n), the process returns to step S4, and steps S4 to S7 are repeated. For example, if the next read position is smaller than the coordinates of the register ED(0), the range of the read divided image 600 is within the range that one gradient index lens 311 can receive, so the lens counter n is left unchanged and reading of the next range begins.

[0067] 8, if the read position of the input image storage unit 404 is equal to or greater than the coordinates of the register ED(n), reading of the input image 500 that can be received by one gradient index lens 311 is completed. In that case, the process proceeds to step S9 as shown in FIG.

[0068] 8, the number in the lens counter n is incremented by 1. This starts reading out the input image 500 within the range that the second gradient index lens 311 can receive.

[0069] 8, if the lens counter n is smaller than the total number of lenses, which is the total number of the gradient index lenses 311 included in the lens array 310 stored in the image processing parameter storage unit 405, the process returns to step S3 and steps S3 to S9 are repeated. As a result, a plurality of segmented images 700 are generated from the entire input image 500 over a range corresponding to the entire lens array 310.

[0070] In step S10 of FIG. 8, if the lens counter n is equal to or greater than the total number of lenses, then the divided images 700 corresponding to all of the gradient index lenses 311 contained in the lens array 310 have been generated and transmitted to the image output unit 406, and the process proceeds to step S11.

[0071] 7 illustrates an example in which the size of the range between lens boundary start position register ST(n) and lens boundary start position register ED(n) in the first direction is equal to the first width W of the divided image 600. In this case, in the flow in FIG. 8, the read position always coincides with register ED(n) in step S8, so that repeated processing is performed between steps S3 and S9.

[0072] In step S11 in Fig. 8, the image output unit 406 transmits all of the multiple segmented images 700 to the light emitting device 300. More specifically, the multiple segmented images 700 are transmitted to a light emitting element driver 306 included in the light emitting device 300. As shown in Fig. 7, in the second embodiment, the light emitting element driver 306 emits light that forms an image of one divided image 600 on one light emitting element group 302 included in the light emitting element array 301 toward the incident end 312 of one refractive index distribution lens 311.

[0073] In FIG. 7, the lens length L2, which is the length of each of the plurality of gradient index lenses 311, is 1 / 4 pitch. Therefore, the image formed by the light incident from the entrance end 312 of the gradient index lens 311 is inverted in the first direction after passing through the gradient index lens 311, and is further enlarged in the first direction. As a result, the segmented image 700 returns to the same orientation and size as the segmented image 600 before image processing. All of the plurality of segmented images 700 return to the same orientation and size as the plurality of segmented images 600 before image processing, and are emitted from the exit end 313 toward the imaged surface 202 and imaged. Therefore, the image formed on the imaged surface 202 has the same orientation and size as the input image 500. Through the above steps, the input image 500, which is one line of image data, is imaged on the imaged surface 202 of the photoconductor 201.

[0074] In step S12 of FIG. 8, the image processing device 401 increments the number of received input images 500 by +1 in a line counter h.

[0075] 8, if line counter h is smaller than the total number of lines for one page stored in input image storage unit 404, the process returns to step S2, and the processes of steps S2 to S12 are repeated for a new input image 500 corresponding to the next line based on the number in line counter h. If line counter h is equal to or greater than the total number of lines for one page in step S13, this means that data on which image processing has been performed on the entire image data has been transmitted to light-emitting device 300, and the process within control device 400 ends.

[0076] <Modification of the second embodiment> 9 is a schematic diagram of the process from image processing to image formation in a modification of the image processing of embodiment 2. The modification of embodiment 2 differs in that the image processing further includes a process of inverting each of the multiple divided images 600 in a second direction perpendicular to the first direction.

[0077] Specifically, as shown in FIG. 9, the image processing device 401 performs image processing on each of the multiple divided images 600 by inverting and reducing the multiple divided images 700 in a first direction, and further inverting the multiple divided images 700 in a second direction perpendicular to the first direction, to generate the multiple divided images 700. In this case, the parameters stored in the image processing parameter storage unit 405 include performing both a process of inverting the divided images 600 left to right and a process of inverting the divided images 600 up to down. Even if the lens length is 1 / 4 pitch, depending on conditions such as the physical characteristics of the refractive index gradient lens 311 and the arrangement relationship between the refractive index gradient lens 311 and the light emitting element group 302, the original image formed by the light incident from the incident end 312 may be imaged on the imaged surface 202 as an image inverted in both the first direction and the second direction when it is emitted from the emission end 313. Even in such a case, this modified example can print the image data received by the image forming device 100 in the same orientation and with the same size, as shown in FIG. 9.

[0078] Although not shown, depending on the shape of the gradient index lens 311 and the difference in the positional relationship between the light emitting element array 301 and the lens array 310, when the lens length L2 is 1 / 4 pitch, the image may be enlarged in the second direction in addition to the first direction. In that case, the image may be reduced in both the first direction and the second direction in the image processing. In that case, the reduction ratio is determined according to the enlargement ratio in both the first direction and the second direction from the original image when the lens length L2 is 1 / 4 pitch, and is set so that the image is formed to have the same size as the original image when it is emitted from the emission end 313, and is stored in the image processing parameter storage unit 405.

[0079] <Embodiment 3> Fig. 10 is a schematic diagram from image processing to image formation in the third embodiment. The third embodiment is a modification of the second embodiment, and illustrates a case where the lens length L2 is 1 / 4 pitch. The third embodiment is different in that the image processing device 401 further generates three intermediate images 604 from the multiple divided images 600 in the image processing performed on the divided images 600, and the three intermediate images 604 are arranged along the first direction to form each of the multiple segment images 700. For simplicity, Fig. 10 illustrates a configuration in which the lens array 310 includes two gradient index lenses 311.

[0080] Depending on conditions such as the physical characteristics of the gradient index lens 311 and the relative positioning of the gradient index lens 311 and the group of light-emitting elements 302, in a gradient index lens 311 with a lens length L2 of 1 / 4 pitch, as shown in Figure 10, three intermediate images 604 lined up in the first direction facing the incident end 312 may be imaged on the imaged surface 202 as a single image, with the left and right images superimposed on the central image at the exit end 313, resulting in triple exposure.

[0081] 10, the image processing device 401 generates intermediate images 604 of a third width Y by reducing each of the multiple divided images 600 so that the width in the first direction is 1 / 3. Specifically, a process is performed to reduce the first width W of one divided image 600 so that the third width Y of one intermediate image 604 becomes W / 3. Thereafter, the image processing device 401 performs image processing to line up and combine the three intermediate images 604 along the first direction to generate one partitioned image 700.

[0082] As shown in Fig. 10, light that forms an image of the divided image 700 is emitted from each of the light emitting element groups 302 and enters one gradient index lens 311. In the third embodiment, when an image formed by light that enters from the entrance end 312 is emitted from the exit end 313, each of the three intermediate images 604 included in the divided image 700 is inverted in the first direction, and further, the images of the three intermediate images 604 arranged in the first direction are superimposed and imaged on the imaged surface 202 as one image having the same orientation and size as the original divided image 600. Therefore, the output image 800 imaged on the imaged surface 202 is a triple-exposed image, and for example, if the light emission conditions of the light emitting element array 301 are the same as those of the second embodiment, the image density of the output image 800 is three times that of the second embodiment. In other words, when forming an output image 800 with the same image density as in embodiment 2, the light intensity of the light-emitting element group 302 or the light-emitting element 303 provided in the light-emitting element array 301 can be reduced to 1 / 3, and the power applied to the light-emitting element 303 can be significantly reduced.

[0083] <Modification of the third embodiment> As a modification of the third embodiment, although not shown, the image processing of FIG. 10 may further include a process of inverting the divided image 600 in a second direction perpendicular to the first direction. That is, in FIG. 10, each of the intermediate images 604 may be further inverted in the vertical direction to form the divided image 700. Depending on conditions such as the physical characteristics of the gradient index lens 311 and the arrangement relationship between the gradient index lens 311 and the light emitting element group 302, even in a configuration similar to that of the third embodiment, an original image formed by light incident from the incident end 312 may be formed on the imaged surface 202 as an image inverted in both the first and second directions when emitted from the emission end 313. Even in such a case, this modification can print the image data received by the image forming apparatus 100 in the same orientation and the same size as in the configuration shown in FIG. 10.

[0084] <Embodiment 4> FIG. 11 is a schematic diagram of the image processing to image formation in the fourth embodiment. The fourth embodiment is a modification of the second embodiment, and illustrates a case where the lens length L2 is 1 / 4 pitch. In the fourth embodiment, the multiple divided images 600 include a first divided image 601 and a second divided image 602 adjacent to each other. The image processing device 401 acquires the first divided image 601 and the second divided image 602, each including an overlapping region 603 that partially overlaps each other. Furthermore, the image processing performed by the image processing device 401 is different in that it includes a process of making the image density of either one of the overlapping region 603 of the first divided image 601 and the overlapping region 603 of the second divided image 602 zero. For simplicity, FIG. 11 illustrates a configuration in which the lens array 310 includes two gradient index lenses 311.

[0085] Depending on the physical characteristics of the gradient index lens 311, the positional relationship between the gradient index lens 311 and the light emitting element group 302, and other conditions, the range of the light image received by two gradient index lenses 311 adjacent to each other in the first direction among the plurality of gradient index lenses 311, and the range of the image imaged on the imaged surface 202 may partially overlap in the output image 800. In that case, the overlapping range on the imaged surface 202 is exposed twice, and the density of the printed image becomes relatively large compared to a non-overlapping range, for example, and partial unevenness occurs. In addition, in the present disclosure, since a process of inversion at least in the first direction is performed on each divided image 600, when the light images of the first divided image 601 and the second divided image 602 adjacent to each other are made to enter the two gradient index lenses 311 adjacent to each other, there is a possibility that a part of the adjacent images may be reflected, an image may be missing, or the like may occur.

[0086] As shown in Fig. 11, when reading a divided image 600 from an input image 500, the image processing device 401 reads the divided image 600 so that a first divided image 601 and a second divided image 602 adjacent to each other include an overlapping region 603 where they partially overlap each other. Fig. 12 is a schematic diagram related to image processing of the fourth embodiment, and relates to processing for setting the overlapping region 603 in each of the first divided image 601 and the second divided image 602. Note that in the following description, a case will be described in which, in the first direction, the first divided image 601 is the image that is read first from the input image 500, and the second divided image 602 is the image that is read next.

[0087] As shown in FIG. 12, the range in which the image processing device 401 reads the first divided image 601 from the input image 500 is the range from the lens boundary start position register ST(0) to the lens boundary start position register ED(0) and is a first width W. Also, the range in which the image processing device 401 reads the second divided image 602 from the input image 500 is the range from the lens boundary start position register ST(1) to the lens boundary start position register ED(1) and is a first width W. Here, the position of the lens boundary start position register ED(1) is set closer to the lens boundary start position register ST(0) than the position of the lens boundary start position register ED(0). This allows the image processing device 401 to read the range between the lens boundary start position register ED(1) and the lens boundary start position register ED(0) as an overlapping region 603, and include it in each of the first divided image 601 and the second divided image 602.

[0088] Next, the image processing device 401 performs image processing to set the image density of either the overlapping region 603 of the first divided image 601 or the overlapping region 603 of the second divided image 602 to zero. In Fig. 11 and Fig. 12, a case is illustrated in which the image processing device 401 sets the image density of the overlapping region 603 of the second divided image 602 to zero, but the image density of the overlapping region 603 of the first divided image 601, instead of the overlapping region 603 of the second divided image 602, may be set to zero.

[0089] Thereafter, the image processing device 401 performs a process of inverting each of the first divided image 601 and the second divided image 602 in a first direction, and further reducing the first width W to a second width X in the first direction to generate a first divided image 701 and a second divided image 702, respectively, in the same manner as in the second embodiment. As a result, the first divided image 701 and the second divided image 702 each include a first divided overlap region 703 corresponding to the overlap region 603 of the first divided image 601 and a second divided overlap region 704 corresponding to the overlap region 603 of the second divided image 602. The image density of the second divided overlap region 704 becomes zero.

[0090] As shown in FIG. 11, light forming an image of the first division image 701 and light forming an image of the second division image 702 are emitted from two adjacent light emitting element groups 302, and are incident on two adjacent refractive index gradient lenses 311. At this time, the image density of the second division overlap region 704 is zero, so the portion corresponding to the second division overlap region 704 becomes a non-illuminated portion without a light image and is not exposed. Since the lens length L2 is 1 / 4 pitch, the image by the light incident from the entrance end 312 becomes an image that is enlarged in the first direction compared to the original image and inverted in the first direction when it is emitted from the exit end 313, and is imaged as the output image 800 on the imaged surface 202. As described above, the portion corresponding to the second division overlap region 704 is not exposed, so that the portion corresponding to the first division overlap region 703 and the portion corresponding to the second division overlap region 704 in the output image 800 are not double exposed. This makes it possible to prevent localized unevenness in the printed image, as well as to prevent the occurrence of partial reflection of adjacent images in overlapping areas, image chipping, and the like.

[0091] <Modification of the fourth embodiment> As a modification of the fourth embodiment, although not shown, the image processing in FIG. 11 may further include a process of inverting each of the first divided image 601 and the second divided image 602 in a second direction perpendicular to the first direction. That is, in FIG. 11, each of the first divided image 601 and the second divided image 602 may be further inverted in the up-down direction before being input to the light-emitting element array 301. Depending on conditions such as the physical characteristics of the gradient index lens 311 and the arrangement relationship between the gradient index lens 311 and the light-emitting element group 302, even in a configuration similar to that of the fourth embodiment, an original image formed by light incident from the incident end 312 may be formed on the image-forming surface 202 as an image inverted in both the first direction and the second direction when emitted from the emission end 313. Even in such a case, this modification can print the image data received by the image forming apparatus 100 in the same orientation and with the same size as in the configuration shown in FIG. 11.

[0092] The present disclosure is not limited to the configurations of the above-described embodiments and modified examples, and may be replaced with a configuration that is substantially the same as the configurations shown in the above-described embodiments and modified examples, a configuration that has the same action and effect, or a configuration that can achieve the same purpose. [Explanation of symbols]

[0093] 100: Image forming device 101: Main unit 102: Image reader 103: Automatic paper feed tray 104: Manual feed tray 201: Photoreceptor 202: Image surface 203: Developing device 204: Transcription unit 205: Primary transfer roller 206: Transfer belt 207: Secondary transfer roller 300: Light emitting device 301: Light emitting element array 302: Light emitting element group 303: Light emitting element 304: Light emitting element array substrate 305: Light emitting element array housing 306: Light emitting element driver 310: Lens array 311: Gradient index lens (GRIN lens) 312:Incidence end 313: Output end 314: Lens array housing L, L1, L2: Lens length 400: Control device 401: Image processing device 402: Image input unit 403: Image correction unit 404: Input image storage unit 405: Image processing parameter storage unit 406: Image output unit 500: Input image 600: Split image 601: First divided image 602: Second divided image 603: Duplicate area 604: Intermediate image 700: Sectional image 701: First section image 702: Second section image 703: Overlapping area after first division 704: Duplicate area after second division 800: Output image

Claims

1. an image processing device that divides an input image in a first direction to generate a plurality of divided images, and performs image processing on each of the plurality of divided images to generate a plurality of section images from the plurality of divided images; a light-emitting element array including a plurality of light-emitting element groups each emitting light corresponding to the plurality of segmented images, each of the plurality of light-emitting element groups including two or more light-emitting elements; a lens array including a plurality of gradient index lenses arranged along the first direction, each of which has a plurality of entrance ends into which light corresponding to the plurality of segmented images is incident, and each of which has a plurality of exit ends from which light that forms an output image on an imaged surface is emitted; A light emitting device, wherein the length of the plurality of gradient index lenses is shorter than the length of one pitch.

2. The length of each of the plurality of gradient index lenses is a half pitch length, The light emitting device according to claim 1 , wherein the image processing includes a process of inverting each of the plurality of divided images in the first direction.

3. The length of each of the plurality of gradient index lenses is a quarter pitch length, The light emitting device according to claim 1 , wherein the image processing includes a process of reducing and inverting each of the plurality of divided images in the first direction.

4. The light emitting device of claim 3, wherein the image processing further includes a process of generating an intermediate image by reducing each of the plurality of divided images so that its width in the first direction is 1 / 3, and arranging and combining the three intermediate images along the first direction to form each of the plurality of segment images.

5. the plurality of divided images include a first divided image and a second divided image adjacent to each other, The light emitting device of claim 3, wherein the image processing includes a process of acquiring the first divided image and the second divided image each including an overlapping area in which the first divided image and the second divided image partially overlap each other, and setting the image density of one of the overlapping area of ​​the first divided image and the overlapping area of ​​the second divided image to zero.

6. The light emitting device according to claim 2 , wherein the image processing further includes a process of inverting each of the plurality of divided images in a second direction perpendicular to the first direction.

7. The light emitting device according to claim 1 , wherein each of the plurality of light emitting elements is an organic light emitting diode.

8. An image forming apparatus comprising: the light emitting device according to claim 1; and a photoconductor having the image forming surface.

Images