JP4840304B2 - Light emitting device and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a light emitting device and an image forming apparatus including the light emitting device, and more particularly to a light emitting device using a light emitting element as a light source and an image forming apparatus including an exposure apparatus including the light emitting device.

2. Description of the Related Art An image forming apparatus such as an electrophotographic system has an exposure apparatus that includes a light emitting device for exposing a photosensitive drum by irradiating light corresponding to image data. In recent years, various attempts have been made to use a light emitting element such as an organic EL element as a light source of such an exposure apparatus. When such a light emitting element is used, there is a variation in the amount of emitted light due to a variation in the light emission characteristics of the light emitting element. For example, data for correcting the light emitting element is previously stored in the memory, and the correction data A technique for correcting the emission intensity based on the above is considered. (For example, Patent Document 1)
JP-A-11-138890

  However, it is known that the light emitting characteristics of the light emitting element as described above change with the passage of time of use, and the amount of emitted light decreases with the passage of time of use. Since correction data is used, changes in characteristics with time are not taken into consideration. For this reason, if the light emission luminance of the element changes with the passage of time, the print quality will deteriorate.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a light emitting device capable of always accurately recognizing and appropriately correcting a change in the amount of light emitted from a light emitting element. It is another object of the present invention to provide an image forming apparatus that can maintain good print quality over a long period of time.

According to the first aspect of the present invention, there is provided a substrate, at least one pixel including a light emitting element having a light emitting portion, which is provided on the upper surface side of the substrate, and between the one surface of the substrate and the light emitting element. A first insulating film that is provided and transmits at least a part of the emission wavelength of the light emitting element; and on the same surface side of the first insulating film as the surface on which the light emitting element is formed, At least one light receiving element having a light receiving part, formed at a distance, and at least the light emitting part of the light emitting element and the light receiving element between the one surface of the substrate and the first insulating film. A first reflection member that is provided in a region excluding a region corresponding to the light receiving unit and reflects at least a part of the light emitted from the light emitting element to enter the light receiving unit; A first electrode having a gate electrode; Material is made of the same material as the gate electrode, characterized in that it is formed on the gate electrode and the same plane.

  The invention according to claim 2 is the invention according to claim 1, wherein the light emitting element is a bottom emission type organic EL element, and the first reflecting member is a position corresponding to the light emitting portion of the light emitting element. And having an opening formed to have a size equal to or smaller than the size of the light emitting portion.

  According to a third aspect of the present invention, in the first aspect of the present invention, the light emitting element is provided in contact with a part of the first reflecting member and an end of the first insulating film on the light emitting element side. And a first connecting portion that is electrically connected to one electrode and reflects at least part of the light emitted from the light emitting element.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the light receiving element is provided in contact with a part of the first reflecting member and an end of the first insulating film on the light receiving element side. And a second connecting portion that is electrically connected to one of the electrodes and reflects at least part of the light emitted from the light emitting element.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, at least a part of the emission wavelength of the light emitting element formed on the first insulating film so as to cover the light receiving element is transmitted. A second insulating film formed by a member, a second reflecting member formed so as to integrally cover the second insulating film and the light emitting element, and reflecting at least part of the light emitted from the light emitting element; And at least part of the light emitted from the light emitting element is reflected by at least one of the first and second reflecting members and propagates through at least one of the first and second insulating films. Then, the light is received by the light receiving element.

  The invention described in claim 6 is the invention described in claim 5, wherein the second reflecting member also serves as one electrode layer of the light emitting element.

  According to a seventh aspect of the present invention, in the fifth aspect of the present invention, a plurality of the pixels are provided on the one surface of the substrate, and the light emitting element is disposed between the second insulating film and the second reflecting member. It further includes a partition wall formed by a member that transmits at least part of the emission wavelength, and separating the pixels.

  The invention described in claim 8 is characterized in that, in the invention described in claim 5, light scattering treatment is applied to the inner surface of the second reflecting member facing the light receiving element.

  According to a ninth aspect of the invention, in the first aspect of the invention, the light emitting element is a top emission type organic EL element, and is disposed on the first insulating film so as to cover the light receiving element. A third insulating film, a transparent conductive film that integrally covers the third insulating film and the light-emitting element, and serves as one electrode layer of the light-emitting element and transmits at least a part of the emission wavelength of the light-emitting element And further comprising.

  A tenth aspect of the invention is the invention according to any one of the first to ninth aspects, wherein a plurality of the pixels are provided on the one surface of the substrate and arranged in an array, and two or more adjacent pixels are arranged. And a plurality of light receiving elements are provided corresponding to each of the plurality of pixel groups.

The invention according to claim 11 is an image forming apparatus that includes a photosensitive drum and an exposure device, and performs printing according to image data, wherein the exposure device applies light to the photosensitive drum according to the image data. A light emitting device that performs exposure by irradiating the substrate, wherein the light emitting device includes a substrate, a plurality of pixels including a light emitting element having a light emitting portion provided on one surface of the substrate, and the one surface of the substrate. And the plurality of light emitting elements, and a first insulating film that transmits at least a part of the emission wavelength of each light emitting element, and each light emitting element on the first insulating film is formed. At least one light receiving element having a light receiving portion formed on the same side of the surface as being spaced apart from each light emitting element,
Each light emitting element provided between the one surface of the substrate and the first insulating film except at least a region corresponding to the light emitting part of the light emitting element and the light receiving part of the light receiving element; A first reflecting member that reflects at least a part of the light emitted from the light and makes it incident on the light receiving unit , wherein the light receiving element includes a gate electrode, and the first reflecting member includes the gate electrode. made of the same material as, you characterized in that it is formed on the gate electrode and the same plane.

  The invention according to claim 12 is the emission wavelength of the light emitting element according to the invention according to claim 11, wherein the light emitting device is further formed on the first insulating film so as to cover the light receiving element. A second insulating film made of a member that transmits at least a part of the light-emitting element, and the second insulating film and the light-emitting element are integrally covered to reflect at least a part of the light emitted from the light-emitting element. A second reflecting member, and at least part of the light emitted from the light emitting element is reflected by at least one of the first and second reflecting members, and the first and second insulating films. Propagating through at least one of them, and being received by the light receiving element.

  According to a thirteenth aspect of the present invention, in the twelfth aspect of the present invention, the light emitting device further includes at least part of the light emission wavelength of the light emitting element between the second insulating film and the second reflecting member. It is characterized by comprising a partition wall formed by a transparent member for separating the pixels.

  According to the present invention, it is possible to always accurately recognize and correct the brightness of each of the plurality of organic EL elements constituting the print head.

(First embodiment)
An exposure apparatus and an image forming apparatus (printing apparatus) according to a first embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus using the exposure apparatus according to the present embodiment. In the figure, an image forming apparatus includes a photosensitive drum 1, an exposure device 2, a charging roller 3, an eraser light source photosensitive member 4, a cleaning member 5, a developing device 6 including a developing roller 6a, and a transfer roller 8. A fixing roller 9 and a conveyor belt 11. Note that reference numeral 7 denotes printing paper.

  The exposure apparatus 2 arranges an exposure head unit in which a plurality of light emitting elements are arranged in an array, and, for example, a SELFOC (registered trademark) lens in an array so as to oppose the plurality of light emitting elements. And a lens portion formed of a rod lens array that forms an image on the photosensitive drum 1 as an equal-magnification erect image.

  The photosensitive drum 1 is a negatively charged OPC (Organic Photo Conductor) photosensitive member (organic photosensitive member), and the charging roller 3 is a negative charger correspondingly.

  In the image forming apparatus shown in FIG. 1, printing is generally performed by the following steps. First, when the charging roller 3 comes into contact with the surface of the rotating photosensitive drum 1, the contacted surface of the photosensitive drum 1 is uniformly charged with a negative potential. Subsequently, the exposure device 2 irradiates the photosensitive drum 1 with light, and an electrostatic latent image is formed on the photosensitive drum 1. Thereafter, toner is attached to the electrostatic latent image by the developing device 6. Then, the toner attached to the electrostatic latent image is transferred to the printing paper 7 by the transfer roller 8. Hereinafter, such a printing process will be described in detail.

  First, a negative high voltage supplied from a charging power source (not shown) is applied to the photosensitive drum 1 by the charging roller 3. As a result, the peripheral surface of the photosensitive drum 1 is uniformly negatively charged, and is in an initialized charged state that is initialized in terms of potential.

  Then, optical writing (exposure) according to the printing information is performed by the exposure device 2 on the photosensitive drum 1 whose peripheral surface is in an initialized charged state. As a result, an electrostatic latent image composed of a negative high potential portion due to initialization charging and a negative low potential portion of about −50 [V] due to exposure is formed on the peripheral surface of the photosensitive drum 1.

  Here, the toner charged in the developing unit 6 and charged to a weak negative potential is rotated and conveyed by the developing roller 6a to the facing portion between the developing roller 6a and the photosensitive drum 1. At this time, a developing bias voltage of about −250 [V], for example, is applied to the developing roller 6a from a power source (not shown).

  Accordingly, between the developing roller 6a to which the developing bias voltage of −250 [V] is applied and the minus low potential portion of about −50 [V] of the electrostatic latent image on the photosensitive drum 1 is about 200 [V]. Is formed.

  Due to the potential difference from the developing voltage in these electrostatic latent images, the negatively charged potential portion in the electrostatic latent image that has a positive polarity relative to the developing roller 6a has a negatively charged toner. Is transferred to form a toner image. The toner image is conveyed to a transfer portion where the photosensitive drum 1 and the transfer roller 8 are opposed to each other by the rotation of the photosensitive drum 1.

  Note that the toner adhesion amount in the toner image formed as described above, that is, the density of the developed image, is generated according to the exposure amount of the photosensitive drum 1 by the light emitting element of the exposure device 2. It is determined by the amount of potential attenuation on the circumferential surface.

  Next, when the toner image is conveyed to the transfer unit as described above, the printing paper 7 is conveyed to the transfer unit by the conveyance belt 11. In the transfer portion, the toner image is transferred onto the printing paper 7 by the transfer roller 8. The printing paper 7 onto which the toner image has been transferred in this manner is conveyed further downstream by the conveying belt 11, and after the toner image is thermally fixed by the fixing roller 9, the printing paper 7 is discharged to the outside of the image forming apparatus. The

  Further, after the toner image is transferred onto the printing paper 7, the residual toner is removed from the peripheral surface of the photosensitive drum 1 by the cleaning member 5, and is further uniformly 0 (zero) [V] by the eraser light source photosensitive member 4. To be charged for the charging roller 3.

  In the exposure apparatus 2, a large number of light emitting elements are arranged as a light emitting element array along the axial direction of the photosensitive drum 1 which is the main scanning direction of exposure scanning on the photosensitive drum 1 shown in FIG. An organic EL array in which organic EL elements are arranged in a line is provided.

FIG. 2 shows a configuration of an exposure head unit provided in the exposure apparatus 2. The exposure head unit has an exposure head substrate including an organic EL panel 23.
The organic EL panel 23 has, as a light emitting element array, an organic EL element that is a light emitting element along the axial direction of the photosensitive drum 1 that is the main scanning direction of exposure scanning onto the photosensitive drum 1 shown in FIG. An organic EL array in which a plurality of pixels are arranged in a line is provided.

  Each pixel is divided into a plurality of pixel groups composed of a predetermined number of pixels. In FIG. 2, it is assumed that the exposure head substrate is composed of a total of 48 pixels of 6 pixels × 8 pixel groups for each pixel group in order to simplify the description.

For example, if the actual exposure head substrate is a printer capable of printing resolution of 1200 [dpi] and A4 paper (long side 297 [mm]), it has a configuration of approximately 14,000 pixels. The organic EL panel 23 also includes a plurality of light emitting elements for measuring the amount of light emitted from each light emitting element corresponding to each pixel group and correcting the amount of light to compensate for changes in the amount of light emitted due to changes in the characteristics of each light emitting element over time. An optical sensor circuit having a light receiving element is provided,
Further, the exposure head unit includes a head controller 20, a data driver 21, and a select sensor driver 22.
In the exposure process by the exposure head section having such a configuration, first, the head controller 20 is supplied with a horizontal control signal / HSYNC and a vertical control signal / VSYNC in accordance with image data from a raster image processor (not shown), a paper size and a conveyance speed. Various other control signals are input.

  The head controller 20 generates drive voltages Vdata1 to 6 based on gradation signals corresponding to the on / off of each pixel of the organic EL panel 23 and the pixel data based on these input signals, and outputs them to the data driver 21. The data driver 21, the organic EL panel 23, and the select sensor driver 22 are driven and controlled.

  The select sensor driver 22 emits selection signals Vsel1 to 8 and refresh signals Rfsh1 to 8 corresponding to the eight pixel groups a1 to a6, b1 to b6,..., H1 to h6 constituting the organic EL panel 23. It sends out to each light receiving element of the sensor circuit, and receives sensor outputs Sout1 to Sout8 which are outputs of the respective light receiving elements according to the light emission luminance of each light emitting element in the pixel group at that time.

FIG. 3 is an equivalent circuit illustrating a part of the organic EL panel 23.
Here, a configuration for a total of three pixels including the adjacent pixels centering on the nth pixel in the mth pixel group of the organic EL panel 23 is shown. Each pixel is composed of a thin film transistor (TFT), a total of two transistors, a selection transistor 31 and a drive transistor 33 for driving an organic EL, and a holding capacitor 32 that holds a signal charge corresponding to the light emission luminance of the pixel. Prepare.

  Further, for these pixels, an optical sensor circuit including a photosensor transistor 35 as a light receiving element, a charge transistor 36 for driving the pixel, a readout transistor 38, and a dark current holding capacitor 37. 30 is provided.

  That is, the selection signal Vsel (m) is connected to the gate electrode of the selection transistor 31. A drive voltage Vdata (n) is applied to the source electrode of the selection transistor 31.

  The drain electrode of the selection transistor 31 is connected to one end of the holding capacitor 32 and the gate electrode of the drive transistor 33. A power supply line is connected to the source electrode of the drive transistor 33, and the drain electrode of the drive transistor 33 and the other end of the holding capacitor 32 are connected to the anode electrode of the organic EL element 34 as a light emitting element. The cathode electrode of the organic EL element 34 is grounded.

  The configuration of the selection transistor 31, the holding capacitor 32, and the drive transistor 33 for driving the organic EL element 34 to emit light is an example of a circuit configuration based on an active drive method using two general TFTs.

  However, the configuration for driving the organic EL element 34 to emit light is not limited, and can be realized with any circuit configuration regardless of 2TFT / 3TFT, active / passive, constant voltage writing / constant current writing, and the like.

  In the present embodiment, in addition, the selection signal Vsel (m) is also applied to the gate electrode of the charging transistor 36 of the photosensor circuit 30. The voltage VDD is applied to the source electrode of the charging transistor 36, and the drain electrode of the charging transistor 36 is connected to the source electrode of the photosensor transistor 35, one end of the dark current holding capacitor 37, and the gate electrode of the reading transistor 38. Is done.

  The gate electrode of the photosensor transistor 35 is disposed at a portion irradiated with the light emission L from the organic EL element 34 as indicated by symbol G in the figure. A signal Rfsh (m) is applied, and the drain electrode of the photosensor transistor 35 is connected to the other end of the dark current holding capacitor 37 and the source electrode of the readout transistor 38 and grounded. Then, the drain electrode of the read transistor 38 is used as a terminal of the sensor output Sout (m), and the value of the drain current Is is detected.

  In the organic EL panel 23, TFTs 35, 36, 38 and a capacitor 37 constituting an optical sensor circuit can be integrally formed by the same semiconductor manufacturing process as the pixel light emitting TFTs 31, 33 and the capacitor 32.

  These photosensor circuits are formed on a scale of one circuit for a plurality of organic EL elements, specifically, one circuit per several thousand pixels. Although only three pixels are shown in FIG. 3, the channel width of the photosensor transistor 35 is formed to be, for example, about the width in the main scanning direction in which one pixel group to capture light emission is arranged. The pixel is arranged at a position parallel to the pixel at a certain distance in the sub-scanning direction.

  Since the light amount correction using the optical sensor circuit is performed by comparison with the initial light amount, it is only necessary to detect a change in the relative light emission amount of the light emitting element of each pixel. For this reason, it is not necessary to provide a photosensor circuit for each pixel, and one photosensor circuit with one photosensor transistor 35 can be provided for a plurality of pixels in one pixel group as in this embodiment. .

  FIG. 4 is a timing chart for explaining the basic operation of the optical sensor circuit 30. In the optical sensor circuit 30, the selection signal Vsel (m) is used as the gate signal of the charging transistor 36. First, when the selection signal Vsel (m) is set to the “H” level and the selection signal Vsel (m) is set to the “H” level, the refresh signal Rfsh (m) is also simultaneously set to the “H” level for a short time, and the charging transistor 36. Then, the read transistor 38 is turned on, and the dark current holding capacitor 37 is discharged.

  Thereafter, when the refresh signal Rfsh (m) is set to the “L” level, the photosensor transistor 35 is turned off. However, the dark current holding capacitor is maintained by maintaining the selection signal Vsel (m) at the “H” level for a certain period thereafter. 37 is charged to VDD.

  In this state, the photosensor transistor 35 is in an off state, the read transistor 38 is turned on in accordance with the charge charged in the dark current holding capacitor 37, and the drain current Is flows.

  In this state, when light emitted from the organic EL element 34 is irradiated onto the semiconductor layer portion of the photosensor transistor 35, carriers are generated in the semiconductor layer between the drain and source of the photosensor transistor 35 according to the amount of light. Thus, a channel is formed, a current flows between the drain and the source, and the dark current holding capacitor 37 starts discharging.

  As a result, the drain current Is of the read transistor 38 decreases. The decrease amount (ΔIs) of the drain current Is is an amount corresponding to the amount of light applied to the gate electrode portion of the photosensor transistor 35.

  The waveform indicated by the symbol B shown in FIG. 4 is a value obtained by converting the value of the drain current Is into a voltage value via a current / voltage conversion circuit (not shown), and corresponds to the change in the current Is.

  That is, as shown in FIG. 4, the voltage signal corresponding to the drain current Is immediately before the selection signal Vsel (m) and the refresh signal Rfsh (m) next becomes “H” level is output as the sensor output Sout (m). As a result, the amount of light emitted from the organic EL element 34 can be acquired.

  Here, the amount of emitted light of each organic EL element 34 is acquired, for example, by sequentially causing the organic EL elements 34 of each pixel of the organic EL panel 23 to emit light in a predetermined light emission period according to the supply timing of the selection signal Vsel (m). The optical sensor circuit 30 corresponding to the pixel group including the organic EL element 34 that emits light can be driven by the selection signal Vsel (m) and the refresh signal Rfsh (m) corresponding to the light emission period.

  By the way, in the organic EL panel 23 to be measured, if the size of one pixel is, for example, 1200 [dpi], the size is about 20 [μm], and the dimension of the organic EL element becomes finer. Therefore, the photosensor transistor 35 must catch light emitted from such a very small area.

  The measurement of the amount of light emitted from each light emitting element by the photosensor transistor 35 is performed to compensate for the change in the amount of light emitted due to the change in the characteristics of each light emitting element over time. In order to improve the quality, it is necessary to further increase the accuracy of measurement of the amount of emitted light.

  In this case, the longer the time during which the photosensor transistor 35 receives light from the light emitting element, that is, the measurement time, the greater the change in the current value of the photosensor circuit, and the higher the measurement accuracy.

  However, since the measurement of the light emission amount of each light emitting element by the optical sensor circuit 30 is performed when the image forming apparatus is started up or when printing is not being performed, increasing the measurement time of the light emission light amount is an original print job. This is not preferable because the printing speed as the image forming apparatus is lowered and the usability is deteriorated.

  Therefore, in order to improve the measurement accuracy without increasing the measurement time, increasing the light receiving efficiency of the photosensor transistor 35 is an effective means.

  In the present embodiment, the optical sensor transistor 35 is configured by optimally arranging the gate electrode formation layer, the drain electrode formation layer, and the metal thin film formed by the gate / drain contact formation process for connecting the gate electrode and the drain electrode in the TFT formation process. In order to improve the light receiving efficiency. The details will be described below with reference to FIG.

  5A is a partial schematic view of the bottom emission type organic EL panel 23 as viewed from above, and FIG. 5B is a cross-sectional view as viewed from line VV in FIG. 5A. is there.

  5A shows an arrangement structure of various electrodes and the like of the organic EL element 34 and the photosensor transistor 35 by removing a layer of a cathode electrode 47 and an overcoat insulating film 56 which will be described later.

  In the organic EL element 34, a reflecting plate 42 made of a metal material selected from chromium, chromium alloy, aluminum, aluminum alloy, etc., having an aperture (opening) 42a formed on one surface of a transparent substrate 41, is formed. A transparent electrode 44, and a contact portion 45A and an anode electrode 45B connected to the transparent electrode 44 via a transparent gate insulating film 43 are formed on the transparent electrode 44 and an opening on the anode electrode 45B. An organic EL light-emitting layer 46 composed of a light-emitting layer and an electron transport layer is provided, and a cathode electrode 47 that also functions as a reflecting member made of a metal thin film is formed thereon by wiring.

  Then, by applying a predetermined voltage between the anode electrode 45B and the cathode electrode 47, holes are injected from the anode electrode 45B and electrons are injected from the cathode electrode 47 into the organic EL light emitting layer 46, where the holes and The electrons recombine and emit light. The light generated by this light emission passes through the gate insulating film 43 and the aperture 42a, and diffuses and radiates in the direction of the other surface side of the transparent substrate 41 as indicated by an arrow L in FIG.

  The diffused light from the organic EL element 34 is formed as a small-diameter light spot by the exposure apparatus 2 composed of a pixel substrate and a lens array constituting the organic EL element 34, and is formed on the photosensitive drum 1. Irradiated as a light beam for resolving each dot.

  The photosensor transistor 35 is formed on the transparent substrate 41 with a certain distance D from the organic EL element 34. That is, the gate insulating film 43 extends on the transparent substrate 41 via the gate electrode 51, the semiconductor layer 40 is provided thereon, and chromium, chromium alloy, aluminum, aluminum are provided on both ends of the semiconductor layer 40. Source / drain electrode layers 52 and 53 made of a metal material selected from an alloy or the like are provided, and a block insulating film 39 is provided between the source / drain electrode layers 52 and 53 on the semiconductor layer 40.

  The contact portion 54 at the end of the gate insulating film 43 is connected to a reflection plate 55 formed on the transparent substrate 41. The upper part of the photosensor transistor 35 and the upper part of the contact part 45A and the anode electrode 45B are protected by the cathode electrode 47 through the overcoat insulating film 56 of transparent resin with the organic EL light emitting layer 46 interposed therebetween. .

  Here, the gate electrode 51 and the reflection plate 55 are made of the same material as the reflection plate 42 of the organic EL element 34, and the contact portion 45A and the anode electrode 45B, the drain electrode layers 52 and 53, and the contact portion 54 are made of the same material. It is formed.

  That is, the photosensor transistor 35 and the reflection plate 55 can be manufactured simultaneously with the manufacturing process of the organic EL element 34 on the transparent substrate 41.

  In the above configuration, the reflecting plate 42 is configured by extending a metal thin film formed by the gate electrode layers of the TFTs 31 and 33 for driving the organic EL element 34. The aperture 42a formed on the reflecting plate 42 is a position facing the organic EL light emitting layer 46, and the size thereof is the same as or slightly smaller than the organic EL light emitting layer 46.

  The contact portion 45A is disposed as close as possible to the organic EL light emitting layer 46 between the reflecting plate 42 and the anode electrode 45B.

  In addition, the reflecting plate 42 is disposed so as to extend as close as possible to the gate electrode 51 of the photosensor transistor 35.

  Further, a contact portion 54 is formed on the reflection plate 55 arranged close to the gate electrode 51 so as to be as close to the photosensor transistor 35 as possible.

  Then, the overcoat insulating film 56 after the photosensor transistor 35 and various wirings are formed is formed so as to be spaced from the contact portion 54 to the photosensor transistor 35 and further to the transparent electrode 44. Thus, the cathode electrode 47 that is formed integrally with the upper portion later forms a closed space around the photosensor transistor 35.

  With the above-described configuration, most of the light emitted from the organic EL light emitting layer 46 is used to irradiate the photosensitive drum 1 (not shown) through the aperture 42a of the reflecting plate 42. The

  On the other hand, of the light emitted from the organic EL light emitting layer 46, the remaining light that has not been emitted to the outside from the aperture 42a is indicated by solid and wavy arrows in the gate insulating film 43 and the overcoat insulating film 56 in the drawing. As described above, the light propagates while being reflected by each reflector, contact portion, electrode layer made of a metal thin film, and the like, and finally most of the light enters the semiconductor layer 40 of the photosensor transistor 35 from above and below.

  That is, in the configuration shown in FIG. 5, light is emitted from the organic EL light emitting layer 46 by increasing the area of the light reflecting member in the closed space around the photo sensor transistor 35 except for the aperture 42a of the reflecting plate 42. The amount of the remaining light that has not been emitted to the outside through the aperture 42a of the light is reduced as much as possible, and as much light as possible is incident on the semiconductor layer 40 of the photosensor transistor 35, so that the photosensor The light receiving efficiency of the transistor 35 can be increased.

  Thereby, light other than the light emitted from the organic EL light-emitting layer 46 to the photosensitive drum 1 is efficiently received by the photosensor transistor 35, and the measurement accuracy of the light emission amount in the organic EL light-emitting layer 46 is improved. The light emission quantity can be corrected more accurately while preventing the print job from being hindered.

  More specifically, as indicated by a solid line arrow in the figure, the organic EL light emitting layer 46 reflects the overcoat insulating film 56 on the upper part thereof through the gate insulating film 43 and to the upper side of the photosensor transistor 35. As indicated by broken arrows in the figure, the organic EL light-emitting layer 46 passes through the gate insulating film 43 to the lower side of the semiconductor layer 40, or temporarily goes around the upper side of the photosensor transistor 35 / the lower side of the semiconductor layer 40. After that, most of the light from the organic EL light-emitting layer 46 scattered in the closed space including the photosensor transistor 35 is transferred to the lower side of the semiconductor layer 40 / upper side of the photosensor transistor 3 and so on. The layer 40 is configured to be irradiated.

  With such a configuration, among the light emitted from the organic EL light emitting layer 46, most of the remaining light that has not been emitted to the outside from the aperture 42a is efficiently converted by the photosensor transistor 35. It can receive light.

  In addition, since the cathode electrode 47, which is one electrode layer for the organic EL light emitting layer 46, is also used as a reflective member covering the whole, an increase in manufacturing steps for forming this structure can be suppressed. .

  In the embodiment described above, the size of the aperture 42a formed on the reflecting plate 42 is equal to the size of the organic EL light emitting layer 46 or smaller than the organic EL light emitting layer 46 as shown in FIG.

  As a result, the ratio of the amount of light applied to the photosensitive drum 1 with respect to the amount of light emitted from the organic EL light-emitting layer 46 is reduced, but not only can the absolute amount of light received by the photosensor transistor 35 be improved, The ratio of light leaking outside from the aperture 42a in the process of propagating while reflecting in the gate insulating film 43 and the overcoat insulating film 56 can be reduced, and light reception by the photosensor transistor 35 is performed more efficiently. it can.

  Therefore, by making the size of the aperture 42a formed on the reflector 42 as small as possible within a range in which the light emission luminance necessary for original printing can be ensured, the amount of light emitted from the organic EL light emitting layer 46 can be reduced. Measurement can be performed more accurately, and the amount of emitted light can be corrected more accurately based on the measurement. As a result, the print quality can be improved.

  In addition, the distance between the organic EL light emitting layer 46 and the contact part 45A at the end of the gate insulating film 43 and the distance between the photosensor transistor 35 and the contact part 54 at the end of the gate insulating film 43 are made as small as possible. The horizontal dimensions shown in FIGS. 5A and 5B are set as compact as possible.

  As a result, the ratio of the light emitted from the organic EL light emitting layer 46 and reduced in the gate insulating film 43 or the overcoat insulating film 56 without being irradiated to the photosensor transistor 35 can be reduced, and the photosensor can be efficiently processed. The light receiving efficiency of light can be further increased by the transistor 35.

  In this case, in FIG. 5B, a gap is provided between the contact portion 54 and the drain electrode layer 52, and the photosensor transistor 35 is circulated between the gate insulating film 43 and the overcoat insulating film 56, and from above to below. As described above, the light sensor transistor 35 receives light traveling from the bottom or from the top to the bottom. However, by setting the gap as small as possible, the ratio of the light that wraps around is reduced, and the contact portion 54 The ratio of light that propagates only in the gate insulating film 43 or only in the overcoat insulating film 56 by reflection may be increased.

  In the above-described embodiment, the reflection plate 42 formed with the aperture 42a and the anode electrode 45B are connected by the contact portion 45A, and the gate electrode layer constituting the anode electrode and the reflection plate 42 has the same potential.

  As a result, in the present invention in which circuits are arranged adjacent to each other with a very small wiring interval including the pitch between a plurality of adjacent organic EL light emitting layers 46, extra parasitic capacitance is generated between the wirings. Reduce as much as possible.

(Modification 1 of the first embodiment)
Although not shown in the above embodiment, as one method for forming a polymer organic EL, there is a method in which a bank made of polyimide or the like is formed and the organic EL is coated therebetween.

  FIG. 6 shows another configuration example of the present embodiment utilizing such a method. FIG. 6A is a partial schematic view of the organic EL panel 23 as viewed from above, and FIG. ) Is a cross-sectional view taken along line VI-VI in FIG. In FIG. 6, since the basic structure is the same as that shown in FIG. 5, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

  6A shows the arrangement structure of the various electrodes of the bottle emission type organic EL element 34 and the photosensor transistor 35 as in the case of FIG. 5A, and the cathode electrode located on the upper part thereof. 47, the overcoat insulating film 56, and the bank 61 are omitted, so that the configuration is the same as that shown in FIG.

  As shown in FIG. 6B, a transparent member such as PMMA is formed between the cathode electrode 47 on the overcoat insulating film 56 except for the organic EL element 34 portion having the organic EL light emitting layer 46. A bank 61 using (polymethyl methacrylate) or PET (polyethylene terephthalate) is formed.

  By adopting such a configuration, the method of forming the organic EL light emitting layer 46 can easily cope with a structure in which a bank serving as a partition wall between pixels is adopted.

(Modification 2 of the first embodiment)
Further, in addition to the structure described with reference to FIG. 5B, as shown in FIG. 7, after the overcoat insulating film 56 is formed, the overcoat insulating film 56 is positioned above the semiconductor layer 40 of the photosensor transistor 35. The surface to be processed may be subjected to a process for forming fine irregularities so as to be a rough surface state in which light is scattered by half etching or sand blasting.

  In that case, if the cathode electrode 47 is formed by vapor deposition or the like after the processing, the surface of the metal thin film, which is the cathode electrode 47 on the semiconductor layer 40 of the photosensor transistor 35, becomes rough.

  Therefore, of the light emitted from the organic EL light emitting layer 46 and incident on the overcoat insulating film 56 via the gate insulating film 43, the light that has reached the scattering processed portion SP is converted into scattered light here. Since the rate of reaching the transistor 35 increases, the light receiving efficiency of the photosensor transistor 35 can be further increased.

(Modification 3 of the first embodiment)
In addition to the structure described with reference to FIG. 6B, the surface of the bank 61 on the upper side of the semiconductor layer 40 of the photosensor transistor 35 is half-etched or sandblasted after the bank 61 is formed, as in FIG. It is also possible to add a process for forming fine irregularities so as to obtain a rough surface state in which light is scattered by, for example.

  In that case, if the cathode electrode 47 is formed by vapor deposition or the like after the processing, the surface of the metal thin film, which is the cathode electrode 47 on the semiconductor layer 40 of the photosensor transistor 35, becomes rough.

  Therefore, of the light emitted from the organic EL light-emitting layer 46 and incident on the bank 61 via the gate insulating film 43 and the overcoat insulating film 56, the light reaching the scattering processed portion SP becomes scattered light here. As a result, the rate of arrival at the photosensor transistor 35 increases, so that the light receiving efficiency at the photosensor transistor 35 can be further increased.

(Second Embodiment)
An exposure apparatus and an image forming apparatus according to the second embodiment of the present invention will be described below with reference to the drawings.
1 for the configuration example of the image forming apparatus using the exposure apparatus according to the present embodiment, FIG. 2 for the configuration of the exposure head unit provided in the exposure apparatus, and a part of the organic EL panel. The equivalent circuit illustrated is basically the same as that of FIG. 3 and the operation timing of the optical sensor circuit is basically the same as that of FIG. 4. Shall be omitted.

  In the present embodiment, the optical sensor transistor 35 is configured by optimally arranging the gate electrode formation layer, the drain electrode formation layer, and the metal thin film formed by the gate / drain contact formation process for connecting the gate electrode and the drain electrode in the TFT formation process. In order to improve the light receiving efficiency. The details will be described below with reference to FIG.

  9A is a partial schematic view of the bottom emission type organic EL panel 23 as viewed from above, and FIG. 9B is a cross-sectional view as viewed from line IX-IX in FIG. 9A. is there.

  FIG. 9A shows an arrangement structure of various electrodes of the organic EL element 34 and the photosensor transistor 35 by removing layers of a cathode electrode 77 and an overcoat insulating film 84 which will be described later.

  In the organic EL element 34, a reflective plate 72 made of a metal material selected from chromium, chromium alloy, aluminum, aluminum alloy, etc., with an aperture 72a formed on a transparent substrate 71, is formed, and a transparent gate insulation is formed thereon. A transparent electrode 74, and a contact portion 75A and an anode electrode 75B connected to the transparent electrode 74 are formed through the film 73, and a hole transport layer, a light emitting layer, and an electron transport are formed in openings on the transparent electrode 74 and the anode electrode 75B. An organic EL light emitting layer 76 composed of layers is provided, and a transparent cathode electrode 77 such as ITO is formed thereon by wiring.

  Then, by applying a predetermined voltage between the anode electrode 75B and the cathode electrode 77, holes from the anode electrode 75B and electrons from the cathode electrode 77 are injected into the organic EL light emitting layer 76, where the holes and The electrons recombine and emit light. The light generated by the light emission passes through the gate insulating film 73 and the aperture 72a, and is diffused and radiated in the direction of the transparent substrate 71 as indicated by an arrow L in FIG. 9B.

  The diffused light from the organic EL element 34 is formed as a small-diameter light spot by the exposure apparatus 2 composed of a pixel substrate and a lens array constituting the organic EL element 34, and is formed on the photosensitive drum 1. Irradiated as a light beam for resolving each dot.

  The photosensor transistor 35 is formed on the transparent substrate 71 with a certain distance D from the organic EL element 34. That is, the gate insulating film 73 extends on the transparent substrate 71 via the gate electrode 81, the semiconductor layer 40 is provided thereon, and chromium, chromium alloy, aluminum, aluminum are provided on both ends of the semiconductor layer 40. Source / drain electrode layers 52, 53 made of a metal material selected from an alloy or the like are provided, a block insulating film 39 is provided between the source / drain electrode layers 52, 53 on the semiconductor layer 40, and an upper portion thereof is over. It is protected by the cathode electrode 77 through the coat insulating film 84.

  The contact portion 82 </ b> A of the gate insulating film 73 is connected to the reflection plate 85 formed on the transparent substrate 71. A reflective plate 86 made of a metal thin film is provided on the upper surface of the gate insulating film 73 located between the photosensor transistor 35 and the organic EL element 34.

  Here, the gate electrode 81 and the reflection plate 85 are formed of the same material as the reflection plate 72 of the organic EL element 34, and the contact portion 75A and the anode electrode 75B, the reflection plate 86, the contact portion 82A and the drain electrode layer 82B are both the same. Formed of material.

  That is, the photosensor transistor 35 and the reflecting plates 85 and 86 can be manufactured simultaneously with the manufacturing process of the organic EL element 34 on the transparent substrate 71.

  In the above configuration, the reflecting plate 72 is formed by extending a metal thin film formed by the gate electrode layers of the TFTs 31 and 33 for driving the organic EL element 34. The aperture 72a formed on the reflecting plate 72 is at a position facing the organic EL light emitting layer 76, and the size thereof is the same as or slightly smaller than the organic EL light emitting layer 76.

  The contact portion 75A is disposed as close as possible to the organic EL light emitting layer 76 between the reflector 72 and the anode electrode 75B.

  In addition, the reflection plate 72 is arranged so as to extend as close as possible to the gate electrode position of the photosensor transistor 35.

  Further, a reflective plate 85 having the same gate width as that of the organic EL light emitting layer 76 is disposed on the transparent substrate 71 across the position where the photosensor transistor 35 is opposed, and the reflective plate 85 and the drain electrode layer are disposed. 82B is formed between the organic EL light-emitting layer 76 and the photosensor transistor 35, and the reflector 86 is formed by the drain electrode layer. It is also realized that the same potential as that of the anode electrode 75B is obtained by bonding.

  With the above-described configuration, most of the light emitted from the organic EL light emitting layer 76 is used to irradiate the photosensitive drum 1 (not shown) through the aperture 72a of the reflector 72. The

  On the other hand, the remaining light that has not been emitted from the aperture 72a propagates while being reflected by the respective reflectors and contact portions as indicated by solid and wavy arrows in the gate insulating film 73 in the figure. Most of the light is applied to the gate electrode portion of the photosensor transistor 35.

  That is, in the configuration shown in FIG. 9, the area of the light reflecting member that covers the transparent electrode 74 is made as large as possible except for the aperture 72a of the reflecting plate 72 and the electrode portion of the photosensor transistor 35, and the organic EL light emitting layer 76 Of the light emitted from the aperture 72a, the amount of the remaining light that has not been emitted to the outside is reduced as much as possible so that as much light as possible enters the gate electrode portion of the photosensor transistor 35. The light receiving efficiency of the photosensor transistor 35 can be increased.

  Thereby, light other than the light emitted from the organic EL light emitting layer 76 to the photosensitive drum 1 is efficiently received by the photosensor transistor 35, and the measurement accuracy of the light emission amount in the organic EL light emitting layer 76 is improved. The light emission quantity can be corrected more accurately while preventing the print job from being hindered.

  In the embodiment described above, the size of the aperture 72a formed on the reflecting plate 72 is equal to the size of the organic EL light emitting layer 76 or smaller than the organic EL light emitting layer 76 as shown in FIG.

  As a result, the ratio of the amount of light applied to the photosensitive drum 1 with respect to the amount of light emitted from the organic EL light emitting layer 76 is lowered, but not only can the absolute amount of light collected by the photosensor transistor 35 be improved, In the process of propagating while reflecting in the gate insulating film 73, the ratio of light leaking outside from the aperture 72a can be reduced, and light reception by the photosensor transistor 35 can be performed more efficiently.

  Therefore, by making the size of the aperture 72a formed on the reflector 72 as small as possible within a range in which the light emission luminance necessary for original printing can be ensured, the amount of light emitted from the organic EL light emitting layer 76 can be reduced. More accurate measurement can be performed, and as a result, the print quality can be improved.

  In the above embodiment, the drain electrode layer 82B for the photosensor transistor 35 and the reflection plate 85 are connected by the contact portion 82A so that the potential between them is the same, so that the circuit can be formed with a very small wiring interval. In the present invention configured as described above, generation of extra parasitic capacitance can be reduced as much as possible.

(Modification 1 of 2nd Embodiment)
Although the bottom emission type organic EL element 34 has been described with reference to FIG. 9, the present embodiment can be similarly applied to the top emission type organic EL element 34.

  FIG. 10 shows a configuration of Modification 1 of the present embodiment adopting a top emission type. FIG. 10A is a partial schematic view of the organic EL panel 23 as viewed from above, and FIG. ) Is a cross-sectional view taken along line XX in FIG. In FIG. 10, since the basic structure is the same as that shown in FIG. 9, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

  When the top emission type organic EL light emitting layer 76 ′ is adopted, it is not necessary to provide the aperture 72 a of FIG. 9 on the reflector 72, and light emitted from the organic EL light emitting layer 76 ′ to the gate insulating film 73 side on the lower surface. While the reflection is repeated in the gate insulating film 73 covered by the anode electrode 75B and the contact portion 75A, the reflection plates 72 and 85, the contact portion 82A and the drain electrode layer 82B, and the reflection plate 86, most of them are optical sensors. Light is received by the transistor 35.

On the other hand, on the upper surface side of the organic EL light emitting layer 76, a transparent cathode electrode 91 is disposed over the entire surface instead of the cathode electrode 77. The transparent cathode electrode 91 is made of, for example, an ITO transparent electrode or IZO (Indium Zinc Oxide).
A transparent insulating film 92 is disposed on the transparent cathode electrode 91 to flatten the entire upper surface, and a transparent protective layer 93 is further formed.

  By adopting such a configuration, it is possible to cope with the top emission type organic EL structure as in the case of the bottom emission type.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention at the stage of implementation. In addition, the functions executed in the above-described embodiments may be implemented in appropriate combination as much as possible. The above-described embodiment includes various stages, and various inventions can be extracted by an appropriate combination according to a plurality of disclosed structural requirements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the effect is obtained, a configuration from which the constituent requirements are deleted can be extracted as an invention.

1 is a diagram illustrating a configuration example of an image forming apparatus according to a first embodiment of the present invention. 2 is a view showing a configuration of an exposure head unit provided in the exposure apparatus according to the embodiment. FIG. The figure which illustrates the equivalent circuit of a part of organic electroluminescent panel concerning the embodiment. 4 is a timing chart for explaining the basic operation of the photosensor circuit of FIG. 3. The partial schematic diagram (Drawing 5 (A)) which looked at the organic EL panel concerning the embodiment from the upper surface, and sectional drawing (Drawing 5 (B)) seen from the VV line. The partial schematic diagram (Drawing 6 (A)) which looked at the organic EL panel of modification 1 concerning the embodiment from the upper surface, and the sectional view seen from the VI-VI line (Drawing 6 (B)). The figure which shows the cross-sectional structure of the modification 2 which concerns on the same embodiment. The figure which shows the cross-sectional structure of the modification 3 which concerns on the same embodiment. FIG. 9A is a partial schematic view of the organic EL panel according to the second embodiment of the present invention as viewed from above (FIG. 9A), and FIG. 9B is a cross-sectional view thereof as viewed from line IX-IX. The partial schematic diagram (Drawing 10 (A)) which looked at the organic EL panel of modification 1 concerning the embodiment from the upper surface, and the sectional view (Drawing 10 (B)) seen from the XX line.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 2 ... Exposure apparatus, 3 ... Charge roller, 4 ... Eraser light source photoconductor, 5 ... Cleaning member, 6 ... Developing device, 6a ... Developing roller, 7 ... Printing paper, 8 ... Transfer roller, 9 ... Fixing roller, 11 ... conveying belt, 20 ... head controller, 21 ... data driver, 22 ... select sensor driver, 23 ... organic EL panel, 31 ... selection transistor (TFT), 32 ... holding capacitor, 33 ... driving transistor (TFT) 34 ... Organic EL element, 35 ... Photosensor transistor (TFT), 36 ... Charging transistor, 37 ... Dark current holding capacitor, 38 ... Read transistor (TFT), 39 ... Block insulating film, 40 ... Semiconductor layer, 41 ... Transparent Substrate, 42 ... reflector, 42a ... aperture, 43 ... gate insulating film, 44 ... transparent electrode, 45A ... contact part 45B ... Anode electrode, 46 ... Organic EL light emitting layer, 47 ... Cathode electrode, 51 ... Gate electrode, 52, 53 ... Drain electrode layer, 54 ... Contact part, 55 ... Reflector, 56 ... Overcoat insulating film, 61 ... Bank 71 ... transparent substrate, 72 ... reflecting plate, 73 ... gate insulating film, 74 ... transparent electrode, 75A ... contact part, 75B ... anode electrode, 76, 76 '... organic EL light emitting layer, 77 ... cathode electrode, 81 ... gate Electrode, 82A ... contact part, 82B ... drain electrode layer, 83 ... drain electrode layer, 84 ... overcoat insulating film, 85 ... reflector, 86 ... reflector, 91 ... transparent cathode electrode, 92 ... transparent insulator, 93 ... Transparent protective layer, SP ... scattering processed part.

Claims (13)

A substrate,
At least one pixel including a light-emitting element having a light-emitting portion, provided on the upper surface side of the substrate;
A first insulating film provided between the one surface of the substrate and the light emitting element, and transmitting at least part of the emission wavelength of the light emitting element;
At least one light receiving element having a light receiving portion formed on the first insulating film on the same surface side as the surface on which the light emitting element is formed and spaced apart from the light emitting element;
Light emission from the light emitting element is provided between the one surface of the substrate and the first insulating film except at least a region corresponding to the light emitting part of the light emitting element and the light receiving part of the light receiving element. A first reflecting member that reflects at least part of the emitted light and enters the light receiving unit;
Equipped with,
The light receiving element includes a gate electrode,
The light emitting device, wherein the first reflecting member is made of the same material as the gate electrode and is formed on the same plane as the gate electrode . The light emitting element is a bottom emission type organic EL element,
The first reflecting member has an opening formed at a position corresponding to the light emitting portion of the light emitting element, the size of which is the same as or smaller than the size of the light emitting portion. The light emitting device according to 1.   Provided in contact with a part of the first reflecting member and an end of the first insulating film on the light emitting element side, electrically connected to one electrode of the light emitting element, and emitted light from the light emitting element The light emitting device according to claim 1, further comprising a first connection portion formed of a reflecting member that reflects at least a part of the light.   Provided in contact with a part of the first reflecting member and an end of the first insulating film on the light receiving element side, electrically connected to one of the electrodes of the light receiving element, and emitted from the light emitting element. The light emitting device according to claim 1, further comprising a second connection portion formed of a reflecting member that reflects at least a part of the light. A second insulating film formed on the first insulating film so as to cover the light receiving element and made of a member that transmits at least part of the emission wavelength of the light emitting element;
A second reflecting member formed so as to integrally cover the second insulating film and the light emitting element, and reflecting at least a part of the light emitted from the light emitting element;
At least part of the light emitted from the light emitting element is reflected by at least one of the first and second reflecting members, propagates through at least one of the first and second insulating films, and receives the light. The light emitting device according to claim 1, wherein the light is received by an element.   The light emitting device according to claim 5, wherein the second reflecting member also serves as one electrode layer of the light emitting element.   A plurality of the pixels are provided on the one surface of the substrate, and each of the pixels is formed by a member that transmits at least part of the emission wavelength of the light emitting element between the second insulating film and the second reflecting member. 6. The light emitting device according to claim 5, further comprising a partition wall for separating pixels.   6. The light emitting device according to claim 5, wherein a light scattering process is performed on an inner surface side of the second reflecting member facing the light receiving element. The light emitting element is a top emission type organic EL element,
A third insulating film disposed on the first insulating film so as to cover the light receiving element;
A transparent conductive film that integrally covers the third insulating film and the light-emitting element and serves as one electrode layer of the light-emitting element and that transmits at least part of the emission wavelength of the light-emitting element;
The light emitting device according to claim 1, further comprising: A plurality of the pixels are provided on the one surface of the substrate and arranged in an array, and have a plurality of pixel groups composed of two or more adjacent pixels,
The light emitting device according to claim 1, wherein a plurality of the light receiving elements are provided corresponding to each of the plurality of pixel groups. An image forming apparatus that includes a photosensitive drum and an exposure device and performs printing according to image data,
The exposure device has a light emitting device that performs exposure by irradiating the photosensitive drum with light according to the image data,
The light emitting device
A plurality of pixels including a substrate and a light emitting element having a light emitting portion provided on one surface of the substrate;
A first insulating film provided between the one surface of the substrate and the plurality of light emitting elements and transmitting at least a part of the light emission wavelength of each of the light emitting elements;
At least one light receiving element having a light receiving portion formed on the first insulating film on the same surface side as the surface on which each light emitting element is formed and spaced apart from each light emitting element;
Each light emitting element provided between the one surface of the substrate and the first insulating film except at least a region corresponding to the light emitting part of the light emitting element and the light receiving part of the light receiving element; A first reflecting member that reflects at least part of the light emitted from the light and enters the light receiving unit;
Equipped with,
The light receiving element includes a gate electrode,
The image forming apparatus, wherein the first reflecting member is made of the same material as the gate electrode and is formed on the same surface as the gate electrode . The light emitting device further includes a second insulating film formed on the first insulating film so as to cover the light receiving element, and a member that transmits at least a part of the emission wavelength of the light emitting element,
A second reflecting member formed so as to integrally cover the second insulating film and the light emitting element, and reflecting at least part of the light emitted from the light emitting element;
Comprising
At least part of the light emitted from the light emitting element is reflected by at least one of the first and second reflecting members, propagates through at least one of the first and second insulating films, and receives the light. The image forming apparatus according to claim 11, wherein the light is received by an element.   The light-emitting device further includes a partition that is formed by a member that transmits at least part of the emission wavelength of the light-emitting element between the second insulating film and the second reflecting member, and that separates the pixels. 13. The image forming apparatus according to claim 12, further comprising:

Images