JP2010076223A - Aligner and method for controlling thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain values of light quantities of light irradiated on a photo-conductor drum constant to a graduation value of image data, and to attempt to uniform the values. <P>SOLUTION: A light emitting element array by a plurality of organic EL elements 36 arrayed on a pixel substrate 12 is used as a light source of an aligner of an electrophotographic system. A plurality of photosensors TFT 92 are provided correspondingly to one or more organic EL elements 36. A temperature measurement EL 100 is set to each photosensor TFT 92 in pairs. The light quantity of light emitted from the organic EL element 36 is detected by the photosensor TFT 92. A value of an emission luminance to the gradation value of image data of each organic EL element 36 is controlled so that the value of the light quantity of light irradiated on the photo-conductor drum 10 to the gradation value of image data is matched with a predetermined value on the basis of a compensated value of the light quantity in accordance with a temperature acquired by the corresponding temperature measurement EL 100. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an exposure apparatus using a light emitting element as a light source and a drive control method thereof.

  2. Description of the Related Art An electrophotographic image forming apparatus (printing apparatus) has an exposure device that performs exposure by irradiating light corresponding to image data onto a photosensitive drum. In this exposure device, a light emitting element such as an LED is used as a light source. Things have been realized. In recent years, attention has been paid to organic electroluminescence elements (hereinafter abbreviated as organic EL elements) capable of producing light emission points with high precision as light emitting elements, and such organic EL elements are used as light sources of this exposure apparatus. Various attempts have been made.

  In such a light source unit in an exposure apparatus for electrophotography, for example, a plurality of LED elements or organic EL elements as light sources are arranged as an array part, and the light source unit is mounted in a form in which a plurality of array parts are arranged. Although it is a unit, each light source has a variation in light emission luminance, and there is also a variation in sensitivity at each position in the photosensitive drum.

  Thus, for example, in Patent Document 1, in such an exposure apparatus, light amount correction data for each light source is obtained and stored in advance, and sensitivity correction data for each position of the photosensitive drum is also obtained and stored in advance. Then, based on the stored correction data, each light source is driven by correcting the drive current of each light source determined according to the image data, and thereby the variation in the light amount of each light source and the variation in sensitivity of the photosensitive drum. Considering this, a technique for forming a good image without density unevenness has been proposed.

  In addition, in an exposure apparatus using an organic EL element or LED element in a printing apparatus, the sensitivity of the photosensitive drum and the light emission luminance of the light source have temperature characteristics, and the density change is generated in the formed image due to the temperature change. End up.

In Patent Document 1, temperature data is obtained by measuring the temperature in the vicinity of the surface of the photosensitive drum with a temperature sensor, and the driving current of each light source corrected based on the light amount correction data and sensitivity correction data is used as the temperature data. A technique for further correction based on this is also proposed.
JP 2007-62100 A

  However, the technology disclosed in Patent Document 1 does not consider any deterioration over time of the light emission characteristics of the light emitting element used for the light source.

  In addition, the temperature of each light emitting element of the light source varies depending on various factors such as printing frequency, printing time, printing rate, etc. as well as the environmental temperature, and the light emission luminance of each light emitting element is changed. Therefore, the density variation for each light source cannot be corrected only by measuring the temperature in the vicinity of the surface of the photosensitive drum with a temperature sensor as in the technique disclosed in Patent Document 1.

  The present invention has been made in view of the above-described points, and an object thereof is to provide a light-emitting device capable of making the amount of light emitted from each light-emitting element of a light-emitting section uniform and a drive control method thereof. And

  The light-emitting device according to claim 1 includes at least one pixel having a light-emitting element, and is provided corresponding to the light-emitting element and a light-emitting unit that emits light according to supplied image data. A light amount measuring unit having at least one light sensor for detecting a light amount of light emitted from the element; and at least one temperature sensor provided corresponding to the light sensor and acquiring a temperature in the vicinity of the light sensor. A light amount value detected by the light sensor of the temperature measurement unit and the light amount measurement unit is corrected based on a temperature characteristic of the light sensor and a temperature acquired by the corresponding temperature sensor of the temperature measurement unit. And a control unit that controls a value of a drive signal supplied to the light emitting unit corresponding to the image data based on the corrected light amount value.

  The light-emitting device according to claim 2 is the light-emitting device according to claim 1, wherein the control unit calculates a light amount of the light emitted from the light-emitting element detected at a first timing by the light amount measurement unit. The first light amount corrected based on the temperature acquired by the temperature measurement unit and the second light output after a predetermined time from the first timing, and emitted from the light emitting element detected by the light amount measurement unit A light amount comparison unit that compares the light amount of the emitted light with a second light amount corrected based on the temperature acquired by the temperature measurement unit, and the first light amount and the second light amount by the light amount comparison unit. A correction data storage unit that holds light amount correction data corresponding to the difference and a gradation signal corresponding to the image data are corrected based on the light amount correction data held in the correction data storage unit, A drive signal output unit for outputting as the drive signal, and having a.

  The light-emitting device according to claim 3 is the light-emitting device according to claim 1 or 2, wherein the light-emitting element in the light-emitting unit and the temperature sensor in the temperature measurement unit are formed on the same substrate. It is characterized by comprising organic EL elements having the same structure.

  The light-emitting device according to claim 4 is the light-emitting device according to claim 3, wherein the temperature measuring unit has both ends of the organic EL element when a constant current is passed through the organic EL element constituting the temperature sensor. A voltage measuring unit that measures a voltage between the two, and acquiring the temperature based on a voltage value measured by the voltage measuring unit and a temperature characteristic of the organic EL element.

  The light-emitting device according to claim 5 is the light-emitting device according to any one of claims 1 to 4, wherein the control unit determines a relationship between a light amount value detected by the optical sensor and a temperature of the optical sensor. Based on the temperature coefficient holding unit that is held in a table, the temperature acquired by the temperature measurement unit, and the value held in the temperature coefficient holding unit, the value of the light amount detected by the light sensor of the light amount detection unit A light amount temperature correction unit that corrects the light intensity.

  The light-emitting device according to claim 6 is the light-emitting device according to any one of claims 1 to 5, wherein the light-emitting unit includes a light-emitting element array in which a plurality of the pixels having the light-emitting elements are arranged, The light quantity measurement unit has a plurality of the light sensors corresponding to each of the one or more light emitting elements, and the temperature measurement unit has a plurality of the temperature sensors corresponding to each of the plurality of light sensors, The control unit controls a value of the drive signal supplied to each of the plurality of pixels based on a temperature acquired by each temperature sensor of the temperature measurement unit.

  The light emitting device drive control method according to claim 7, further comprising: a light emitting unit in which at least one pixel having a light emitting element is arranged, and light corresponding to image data supplied from the light emitting element of the light emitting unit. A method for driving the light emitting device to emit light, the step of causing the light emitting element of the light emitting unit to emit light and detecting the amount of light emitted from the light emitting element by an optical sensor, and corresponding to the optical sensor A step of acquiring a temperature in the vicinity of the optical sensor by a temperature sensor provided, and correcting the value of the light amount detected by the optical sensor based on the temperature acquired by the temperature sensor, and the corrected light amount And a step of controlling a value of a drive signal supplied to the light emitting unit corresponding to the image data based on the value of the image data.

  The light-emitting device drive control method according to claim 8 is the light-emitting device drive control method according to claim 7, wherein the step of controlling the value of the drive signal is detected by the optical sensor at a first timing. Correcting the light quantity of the light emitted from the light emitting element based on the temperature acquired by the temperature sensor to obtain a first light quantity, and a first time after a predetermined time has elapsed from the first timing. Correcting the light amount of the light emitted from the light emitting element detected by the light sensor at the timing of 2 based on the temperature acquired by the temperature sensor to obtain a second light amount; A step of comparing the first light amount and the second light amount, and a gradation signal corresponding to the image data, and a light amount corresponding to a difference between the first light amount and the second light amount, which is held in advance. Supplement Is corrected on the basis of the data, characterized in that it comprises the steps of: outputting as the drive signal.

  The drive control method for a light emitting device according to claim 9 is the drive control method for a light emitting device according to claim 7 or 8, wherein the temperature sensor has an organic EL element having the same structure as the light emitting element. The step of acquiring the temperature includes a step of supplying a constant current to the organic EL element constituting the temperature sensor at a timing of acquiring the temperature, and both ends of the organic EL element when the constant current is supplied. Measuring the voltage between the two, and acquiring the temperature based on the value of the measured voltage and the temperature characteristic of the organic EL element.

  The light emitting device according to the present invention may be applied to an exposure device of an image forming apparatus that includes a photosensitive drum, a charger, an exposure device, and a development device and performs printing according to image data. it can. In this case, the exposure device includes a light emitting unit having a light emitting element array in which a plurality of pixels having light emitting elements are arranged and irradiating the photosensitive drum with light according to the image data to perform exposure. A light quantity measuring unit provided corresponding to the light emitting elements, and having a plurality of light sensors for detecting the light quantity of light emitted from the light emitting elements, and a pair of the light sensors. A temperature measuring unit having a plurality of temperature sensors for acquiring temperatures in the vicinity of the respective light sensors, and a light amount value detected by each of the light sensors of the light amount measuring unit, the corresponding temperature of the temperature measuring unit. A control unit that corrects based on the temperature acquired by the sensor and controls a value of a drive signal supplied to the light emitting unit according to the image data based on the corrected light amount value. Become.

  The control unit is configured to correct a light amount of light emitted from each light emitting element detected at a first timing by the light amount measurement unit based on a temperature acquired by the temperature measurement unit; The light amount of the light emitted from each light emitting element detected by the light amount measurement unit at the second timing after a predetermined time has elapsed from the first timing is set to the temperature acquired by the temperature measurement unit. A light amount comparison unit that compares with a second light amount corrected based on the correction amount, a correction data storage unit that stores light amount correction data according to a difference between the first light amount and the second light amount by the light amount comparison unit, A drive signal output unit that corrects a gradation signal corresponding to image data based on the light amount correction data held in the correction data storage unit and outputs the correction signal as the drive signal.

  Each of the light emitting elements in the light emitting element array and each of the temperature sensors in the temperature measuring unit are configured by, for example, organic EL elements having the same structure formed on the same substrate.

  The temperature measuring unit includes a voltage measuring unit that measures a voltage between both ends of the organic EL element when a constant current is passed through the organic EL element constituting the temperature sensor. The temperature is obtained based on the measured voltage value.

  In addition, the control unit includes a temperature coefficient holding unit that holds the relationship between the value of the light amount detected by the optical sensor and the temperature of the optical sensor in a table, the temperature acquired by the temperature measuring unit, and the temperature A light amount temperature correction unit that corrects a light amount value detected by each of the light sensors of the light amount detection unit based on the value held in the coefficient holding unit.

  According to the present invention, the optical sensor for light emission luminance compensation of the light emitting elements of the light emitting element array is provided, and the temperature in the vicinity of the optical sensor is detected by the temperature sensor, thereby correcting the temperature of the light amount detected by the optical sensor. By correcting the amount of light emitted from each light-emitting element based on the detected light quantity corrected for temperature, it is possible to accurately correct variations in light-emitting brightness, deterioration with time, and changes in light-emitting brightness due to temperature, and The amount of light emitted from the element can be made uniform.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  Light-emitting elements composed of organic EL elements, which have been actively studied in recent years for use as light-emitting pixels such as displays, are manufactured by patterning in pixel size on a flat substrate, thus eliminating the need for wire bonding to each light-emitting element. be able to. However, even in the organic EL element, there are variations in the light emission characteristics between the light emitting elements. In addition, there are changes in light emission characteristics over time and temperature characteristics, which may increase variations in the light emission characteristics.

  FIG. 1 is a diagram illustrating an example of a configuration of an image forming apparatus (printing apparatus) according to an embodiment of the present invention. As shown in the figure, the image forming apparatus includes a photosensitive drum 10, an organic EL head (exposure unit) 16 including a pixel substrate 12 and a lens array 14, a charging roller 18, an eraser light source photosensitive member 20, and the like. , A cleaning member 22, a developing device 26 including a developing roller 24, a transfer roller 28, a fixing roller 30, and a conveyance belt 32.

  The photosensitive drum 10 is, for example, a negatively charged OPC photosensitive member (organic photosensitive member). In this case, the charging roller 18 is a negative charger. The developing device 26 is a developing device that performs development with negatively charged toner. The pixel substrate 12 has a light emitting element array (light emitting portion) in which a plurality of organic EL elements are arranged in a line in an array, as will be described in detail later.

  By the way, in the image forming apparatus shown in FIG. 1, printing is roughly performed by the following steps. First, the photosensitive drum 10 is uniformly charged by the charging roller 18. Subsequently, the plurality of light emitting elements on the pixel substrate 12 irradiate the photosensitive drum 10 with light through the lens array 14, and an electrostatic latent image is formed on the photosensitive drum 10. Thereafter, the developer 26 attaches toner to the electrostatic latent image. Then, the toner attached to the electrostatic latent image is transferred to the printing paper 34 by the transfer roller 28. Hereinafter, such a printing process will be described in detail.

  First, the photosensitive drum 10 is a negatively charged OPC (Organic Photo Conductor) photosensitive member, and a negative high voltage supplied from a charging power source (not shown) is applied by a charging roller 18 which is a negative charger. As a result, the peripheral surface of the photosensitive drum 10 is uniformly negatively charged, and is initialized in terms of potential (becomes an initialization charging state).

  The photosensitive drum 10 whose peripheral surface is in the initial charged state is irradiated with light from the light emitting elements on the pixel substrate 12, and optical writing (exposure) is performed according to the printing information. As a result, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 10 from a negative high potential portion due to initialization charging and a negative low potential portion of, for example, “−50 V” due to exposure.

  Next, the toner charged in the developing unit 26 and charged to a weak negative potential is rotated and conveyed by the developing roller 24 to the opposite portion between the developing roller 24 and the photosensitive drum 10. At this time, for example, a developing bias of “−250 V” is applied to the developing roller 24 from a power source (not shown). Therefore, a potential difference of “−200 V” is formed between the developing roller 24 to which a development bias of “−250 V” is applied and the “−50 V” minus low potential portion of the electrostatic latent image on the photosensitive drum 10. Is done.

  Due to this potential difference, the toner charged in the negative polarity is transferred to the negative low potential portion in the electrostatic latent image that has a positive polarity potential relative to the developing roller 24 to form a toner image. . The toner image is conveyed to a transfer portion where the photoconductive drum 10 and the transfer roller 28 face each other by the rotation of the photoconductive drum 10.

  Note that the toner adhesion amount (developed image density) in the toner image formed as described above is generated according to the exposure amount of the photosensitive drum 10 by the light emitting element of the pixel substrate 12. It is determined by the potential difference on the circumferential surface.

  Next, when the toner image is conveyed to the transfer unit as described above, the printing paper 34 is conveyed to the transfer unit by the conveyance belt 32. In the transfer portion, the toner image is transferred onto the printing paper 34 by the transfer roller 28. The printing paper 34 to which the toner image has been transferred in this manner is further conveyed downstream, and after the toner image is thermally fixed by the fixing roller 30, the printing paper 34 is discharged to the outside of the image forming apparatus.

  Further, after the toner image is transferred onto the printing paper 34, the residual toner is removed from the photosensitive drum 10 by the cleaning member 22, and the charge is uniformly discharged to 0V by the eraser light source photosensitive member 20. 18 is prepared for charging.

  It should be noted that the main scanning direction of the exposure scanning on the photosensitive drum 10 shown in FIG. 1 (the width direction of the photosensitive drum 10, that is, the width of the printing paper 34) is placed on the pixel substrate 12 in the organic EL head 16. (Orientation) is provided with an organic EL element array (light-emitting element array: light-emitting portion) in which a large number of light-emitting elements are arranged in a line. This organic EL element array is used when the image forming apparatus is an image forming apparatus capable of printing with a print density of 1200 dpi (dots / inch) to the full width using, for example, A4 size printing paper in the vertical direction. About 14,000 light emitting elements are provided. A signal in accordance with print information output from a host device (not shown) is applied to these individual light emitting elements. That is, the light emission of each light emitting element is selectively controlled.

  Hereinafter, the basic structure of the organic EL element which is a light emitting element will be described with reference to FIG. FIG. 2 is a cross-sectional view of the pixel substrate 12 in the short direction showing the basic structure of the organic EL element on the pixel substrate 12.

  The organic EL element 36 as a light emitting element is formed on the pixel substrate 12 such as glass as shown in FIG. 2, and is sandwiched between opposing substrates 38 such as glass. The periphery of the pixel substrate 12 and the counter substrate 38 is sealed with a sealing material (not shown). Specifically, as the organic EL element 36, a pixel electrode 40, a hole transport layer (HTL) 42, a light emitting layer (EML) 44, an electron transport layer (ETL) 46, and a counter electrode 48 are formed on the pixel substrate 12. They are formed in this order, and are sealed with a counter substrate 38 and a sealing material (not shown).

  That is, the light-emitting material of the organic EL element 36 is easily affected by moisture, and is sealed so as not to come into direct contact with outside air containing moisture.

  Here, the organic EL element 36 has a bottom emission structure in which the light hν of the light emitting layer 44 is emitted from the pixel substrate 12 side.

  The pixel electrode 40 functions as an anode and has a transparent structure including a transparent conductive metal oxide layer such as ITO.

  The counter electrode 48 functions as a cathode, and is formed of a material such as an aluminum-based alloy (AlNdTi) in view of the fact that the thermal conductivity of pure aluminum is as high as 240 w / m · k. The Further, it may be a multilayer reflective structure of a low work function electron injection layer on the lower layer side and a high work function metal layer such as light reflective aluminum on the upper layer side. The counter electrode 48 is preferably a single electrode common to the plurality of organic EL elements 36.

  Conversely, when the pixel electrode 40 is a cathode and the counter electrode 48 is an anode, the carrier transport layer in contact with the pixel electrode 40 is an electron transporting layer, and the carrier transport in contact with the counter electrode 48 is performed. The layer becomes a hole transporting layer.

  The light emitting layer 44 includes an organic material that emits light by recombining holes transported from the HTL 42 and electrons transported from the ETL 46. The carrier transport layer of the organic EL element 36 is not limited to the three-layer structure of the HTL 42, the light emitting layer 44, and the ETL 46. For example, the carrier transport layer may have a two-layer structure of a hole transport layer and an electron transport light emitting layer. There may be only an electron transporting light emitting layer, a hole transporting light emitting layer and an electron transporting layer, and there is no particular limitation such as interposing another carrier transporting layer therebetween. The carrier transport layers such as the HTL 42, the light emitting layer 44, and the ETL 46 are collectively referred to as an EL layer 50.

  When a predetermined voltage is applied between the pixel electrode 40 (anode) and the counter electrode 48 (cathode), holes from the pixel electrode 40 and electrons from the counter electrode 48 emit light. It is injected into the layer 44, and holes and electrons recombine in the light emitting layer 44 to emit light. That is, the energy gap from the cathode to the anode is converted into fluorescence or phosphorescence of the light emitting layer 44. The light hν generated by this light emission passes through the transparent pixel electrode 40 and the pixel substrate 12 and radiates completely.

  The organic EL element 36 is formed by arranging pixel electrodes 40 in an array (printing density) on the pixel substrate 12 to construct an EL layer 50 to be an organic EL element. 50 is sandwiched.

  As described above, in the electrophotographic image forming apparatus, the organic EL head 16 performs optical writing on the photosensitive drum 10 in accordance with the printing information, but on the photosensitive drum 10 separated by a distance of several millimeters. It is difficult to form a light beam with a small diameter and create a light beam that resolves each dot. Therefore, in this embodiment, as shown in FIGS. 3A and 3B, a light spot is formed by combining a rod lens array frequently used in a conventional exposure head or scanner and an organic EL light emitter. Realize. That is, the diffused light from the organic EL element 36 is photosensitized by a distance of millimeter order from the organic EL head 16 by the organic EL head 16 including the pixel substrate 12 and the lens array 14 constituting the organic EL element 36. A small-diameter light spot is formed on the body drum 10 to create a light beam for resolving each dot.

  The organic EL head 16 will be described below with reference to FIGS. 3 (A) and 3 (B). FIG. 3A is a view showing the appearance of the organic EL head 16, and FIG. 3B is a side sectional view of the organic EL head 16. As described above, in the present embodiment, the organic EL element 36 is set to a bottom emission structure.

  In the case portion 52 of the organic EL head 16, a plurality of organic EL elements are arranged in the main scanning direction of the exposure scanning on the photosensitive drum 10 (the width direction of the photosensitive drum 10, that is, the width direction of the printing paper 34). 36 forms an organic EL element array (not shown) arranged in a line.

  The organic EL element 36 is electrically connected to a head controller (not shown in FIG. 3) as will be described in detail later by a control cable 54 as shown in FIG. Here, the connection method between the control cable 54 and the organic EL element 36 may be any connection method as long as the organic EL element 36 can be driven.

  The case portion 52 of the organic EL head 16 includes a front case 56 and a back case 58 as shown in FIG. The pixel substrate 12 is bonded to the front case 56 by, for example, an adhesive resin (not shown). A rear case 58 is fitted into the front case 56.

  Here, in the surface of the pixel substrate 12 opposite to the surface on which the adhesive resin (not shown) is provided, the portion where the organic EL element 36 is not provided is shown in FIG. As shown, a driver IC 60 for driving the organic EL element 36 is provided so as to be electrically connected to the pixel electrode 40 and the counter electrode 48.

  The driver IC 60 receives data signals and timing signals as will be described later from the head controller (not shown in FIG. 3), and the driver IC 60 receives the pixel electrode 40 and the counter signal based on these signals. The electrode 48 is controlled.

  In the present embodiment, because of the structure of the image forming apparatus, the organic EL head 16 is a single device, and thus there is a possibility that force is applied to the connection wiring during assembly or replacement. Accordingly, regarding the cable for connection wiring between the pixel substrate 12 and the head controller, the cable outside the case portion 52 is stronger and has excellent workability as a separate cable inside and outside the case portion 52. In order to obtain a cable, two relay connectors 62 are provided on the rear case 58 as shown in FIG. Each of the relay connectors 62 is connected to a wiring 64, and one of the wirings 64 is used for a signal group to be described later for applying an anode voltage, and a photo sensor circuit and a temperature sensor circuit (both described later). 3 is a wiring for supplying a detection signal from the head controller to the head controller, and the other is a wiring for a signal supplied to the counter electrode 48 in order to apply a cathode voltage.

  The front case 56 is provided with a convex portion 66, an opening is formed in the convex portion 66, and the rod lens array 14 is fitted into the opening so as to face each organic EL element 36. And the rod lens array 14 are sealed with an adhesive. Therefore, even if the front case 56 is opaque to visible light, the light emitted from the organic EL element 36 is incident on the rod lens array 14 through the sealed space 68 formed in the convex portion 66. become.

  The organic EL element 36 shown in FIG. 3B has a bottom emission structure in which the pixel substrate 12 faces the rod lens array 14.

  Further, since the convex portion 66 ensures a certain length of the optical path from the organic EL element 36 to the rod lens array 14, the distance between the rod lens array 14 and the photosensitive drum 10 can be easily set. There is.

FIG. 4 is a block diagram showing an electrical configuration of the image forming apparatus, and FIG. 5 is a diagram showing a more detailed configuration of the head drive unit in FIG.
A CPU 70 that is a control unit that controls the entire image forming apparatus according to the present embodiment, according to dot position information detected by the image processing control circuit 72 from a video signal that is print information output from a host device (not shown). The line head data is read, synchronous control is performed in accordance with the conveyance speed of the printing paper 34, and a horizontal control signal / HSYNC and a vertical control signal / VSYNC signal are generated and sent to the head drive unit 74. Further, the image processing control circuit 72 sends the image data to the head driving unit 74 while synchronizing with these control signals. Further, although not particularly illustrated, the CPU 70 also sends a printer control signal such as a paper size to the head driving unit 74.

  The head drive unit 74 includes a head controller 76 (control means) and the driver IC 60 and the organic EL panel 78 disposed on the pixel substrate 12 of the organic EL head 16. The head controller 76 receives the image data, the horizontal control signal / HSYNC, the vertical control signal / VSYNC, and the printer control signal, and drives the driver IC 60 in accordance with these control signals.

  The driver IC 60 includes a data driver 80 that generates a drive current having a current value based on a gradation signal corresponding to on / off of each pixel of the organic EL panel 78 and image data, a select driver 82 that selects each pixel, And a sensor driver 84 for driving the optical sensor circuit and the temperature sensor circuit to detect the light quantity and temperature.

  The organic EL panel 78 includes an organic EL element array in which the plurality of organic EL elements 36 are arranged in a row, and a circuit unit such as a drive circuit, an optical sensor circuit, a temperature sensor circuit, and wiring between them as described later. And consist of

  FIG. 6 is a diagram showing a circuit configuration of the organic EL panel 78. The drive circuit for driving the organic EL element 36 can be realized by any method regardless of the active method / passive method, constant voltage writing / constant current writing, or the like.

Here, an active matrix driving method will be described as an example.
FIG. 6 shows an example of a pixel driving circuit adopting an active driving method of constant voltage writing using two thin film transistors (hereinafter abbreviated as TFT). This driving circuit is composed of two TFTs, a driving TFT 86 and a selection TFT 88, which are simultaneously manufactured in the manufacturing process of the organic EL element 36, and a holding capacitor 90 therebetween. The organic EL element 36 is connected in series to the driving TFT 86. It has a configuration.

  In such a configuration, when the selection signal Vsel supplied from the select driver 82 is set to the high level and the selection TFT 88 is turned ON, the data voltage Vdata supplied from the data driver 80 is written to the holding capacitor 90 and at the same time, the driving TFT 86. Set to ON. At this time, since the gate voltage Vgs (Vgs = Vdata−Vsource) of the selection TFT 88 is determined according to the data voltage Vdata, the conductivity of the driving TFT 86 is determined. Then, a current corresponding to the conductivity flows from the power supply line to the organic EL element 36.

  In FIG. 6, only three pixels extracted partially are shown, but the data driver 80 drives eight organic EL elements 36 with one data voltage Vdata as an example. In the example of FIG. 5, the organic EL panel 78 has eight pixel groups, each pixel group has six pixels, and data voltages Vdata1 to Vdata6 are applied to each pixel of each pixel group, A gradation signal voltage corresponding to image data is supplied to each pixel. Selection signals Vsel1 to Vscan8 are supplied from the select driver 82 to the organic EL panel 78, and are applied to each of the pixel groups to which the data voltages Vdata1 to Vdata6 are applied. Therefore, in the example of FIG. 5, the organic EL panel 78 has 6 * 8 = 48 pixels formed in the horizontal direction. Actually, as described above, the image forming apparatus has, for example, about 14,000 light emitting elements, and it goes without saying that the number of data voltages and selection signals is larger.

FIG. 7 is a diagram illustrating a timing chart during printing.
That is, in the exposure process at the time of printing, first, the data driver 80 controls the gradation signal supplied from the head controller 76 during the period in which the horizontal control signal / HSYNC is active to active (1 DotLineTime) according to the control by the head controller 76. Accordingly, the data voltages Vdata1 to Vdata6 which are the gradation signal voltages of the respective pixels are generated and applied. At this time, control is performed so that power is supplied to the power supply line. Further, simultaneously with the supply of the data voltages Vdata1 to Vdata6, selection signals Vsel1 to Vscan8 that are sequentially set to a high level (hereinafter referred to as H level) are applied from the select driver 82 in accordance with control by the head controller 76. Thereby, the selection TFT 88 of each pixel is turned on, a gate voltage based on each data voltage Vdata is applied to the gate terminal of the drive TFT 86, and the drive TFT 86 is turned on in a conductive state corresponding to the gate voltage. . As a result, a light emission driving current having a current value based on the data voltage Vdata flows through the driving TFT 86 and the organic EL element 36 of the pixel group to which the selection signal of the pixel group is supplied via the power line, and the organic EL element 36 emits light with a predetermined light emission luminance (Vsel selection period).

  At this time, the data voltage Vdata, which is a gradation signal voltage, is supplied to the holding capacitor 90 via the selection TFT 88, and each holding capacitor 90 is charged to a charge amount having a value corresponding to the level of the gradation signal voltage. The

  Next, when the Vsel selection period has elapsed and the selection driver 82 sets the selection signal Vsel to a low level (hereinafter, L level), the selection TFT 88 is turned off, but the holding capacitor 90 has a gradation signal voltage. Since the corresponding charge amount is held, the driving TFT 86 becomes conductive according to the charge amount held in the holding capacitor 90, and continues the light emitting operation (Vsel non-selection period).

  Thereafter, the horizontal control signal / HSYNC corresponding to the number of lines performs light emission driving for the time from the active period to the active period.

Next, the optical sensor circuit will be described.
The light emission luminance in a light emitting element such as the organic EL element 36 increases in proportion to the magnitude of the interelectrode current across the light emitting layer 44 of the organic EL element 36. Accordingly, when high-speed printing is performed by an image forming apparatus including a light-emitting device that uses the organic EL element 36 as a light source, a considerable amount of energy (in luminance, tens of thousands of cd / m) is obtained in order to obtain the amount of light required for the high-speed printing. ² ) is required. For this reason, since the current value of the current flowing through the organic EL element 36 is set to a relatively large value, Joule heat is generated by this current. Accordingly, as a result, the temperature of the organic EL element 36 increases.

  The image forming apparatus according to the present embodiment attempts to improve the uniformity of the light emission luminance by detecting the light emission amount with an optical sensor circuit and correcting the data voltage Vdata based on the detection result. That is, constant luminance driving by optical feedback is performed. In such an optical feedback configuration, since the optical sensor is provided in the vicinity of the light emitting element, the temperature of the optical sensor also increases as the temperature of the light emitting element increases. In the present embodiment, focusing on the fact that this optical sensor circuit also has a characteristic change due to a temperature change, in addition to constant luminance driving by optical feedback, the temperature of the optical sensor circuit is further obtained by acquiring the temperature of the optical sensor circuit. Control for compensating for a change in characteristics due to a temperature change is performed, whereby the uniformity of light emission luminance can be further improved.

  As shown in FIG. 6, the optical sensor circuit is provided with one circuit for a plurality of (three in this example) pixels. The optical sensor circuit includes three TFTs including a photosensor TFT 92, a charge TFT 94, and a readout TFT 96; And a dark current holding capacitor 98.

FIG. 8 is a diagram illustrating a timing chart during light quantity measurement.
The sensor driver 84 generates an SCG signal and a refresh signal RFSH signal according to a timing signal from the head controller 76. The SCG signal is supplied to the gate of the charging TFT 94 to control the charging TFT 94, and the refresh signal RFSH is supplied to the gate of the photosensor TFT 92.

  That is, when the sensor driver 84 asserts the SCG signal, the charging TFT 94 is turned on. When the charging TFT 94 is turned on, the reading TFT 96 is also turned on to charge the dark current holding capacitor 98. However, when the SCG signal is asserted, the sensor driver 84 also asserts the refresh signal RFSH at the same time, and discharges the dark current holding capacitor 98.

  Thereafter, the sensor driver 84 negates the refresh signal RFSH to turn off the optical sensor TFT 92. The SCG signal is asserted sufficiently longer than the refresh signal RFSH to charge the dark current holding capacitor 98, so that the charge is made the same every time. In this state, the photosensor TFT 92 is in an off state, the read TFT 96 is turned on in accordance with the charge charged in the dark current holding capacitor 98, and the current Is is observed.

In this state, when light is applied to the gate portion of the photosensor TFT 92, a drain-source channel of the photosensor TFT 92 is formed according to the amount of light, current flows, and the dark current holding capacitor 98 starts discharging, As a result, the drain current Is of the readout TFT 96 decreases.
Accordingly, if the change ΔIs of the current Is is observed, the light emission amount of the pixel can be obtained.

  Therefore, the sensor driver 84 performs A / D conversion on the light amount Sout obtained by current-voltage conversion of the current Is and supplies it to the head controller 76 as an optical sensor output.

Next, the temperature sensor circuit will be described.
FIG. 9 is a diagram showing a planar structure of the organic EL head 16.
The photosensor circuit is formed on a scale of one circuit for a plurality of pixels. In FIG. 6, only three pixels extracted partially are shown. However, as shown in FIG. 9, the photosensor TFT 92 is a channel having a width in the main scanning direction in which pixels to be captured are arranged. It is efficient and desirable to form it with a width and arrange it directly below the pixel in the sub-scanning direction.

  In such a structure, the heat generated in the organic EL element 36 will affect the photosensor TFT 92. That is, since the organic EL element 36 is very small, the amount of heat generated by the single element has little effect on the photosensor TFT 92, but a plurality of organic EL elements 36 in a certain region are almost at the same time as in this configuration. If light is emitted repeatedly, the effect of heat occurs.

  Since the optical sensor TFT 92 has temperature characteristics, the generated heat causes an error in the light receiving sensitivity of the optical sensor TFT 92. For example, when the photosensor TFT 92 is made of amorphous Si, the temperature coefficient is about −0.2 to −0.3% / ° C., and an error of 2 to 3% is caused by a change of 10 ° C.

  Therefore, by measuring the temperature closest to the photosensor TFT 92 and correcting the light emission amount obtained from the photosensor TFT 92 with the temperature coefficient based on the measured temperature, the uniformity of the emission luminance can be improved.

  As a temperature sensor circuit therefor, the image forming apparatus according to the present embodiment is provided with a temperature measurement EL 100 as shown in FIG. As shown in FIG. 9, it is desirable that the temperature measurement EL 100 is paired with the photosensor TFT 92 and is disposed in the immediate vicinity of the photosensor TFT 92. Since the temperature measurement EL 100 can be constructed by the same process as the organic EL element 36 constituting the light emitter, that is, the temperature measurement EL 100 can be formed simultaneously with the formation of the organic EL element 36, the manufacturing process increases. There is no such thing.

FIG. 10 is a diagram showing the results of measuring the temperature characteristics when the polymer organic EL material using the conjugated polymer is driven with a constant current. Both ends when driven at a constant current at each luminance of 2500, 5,000, 7,500, 10,000 cd / m ² when the temperature of the glass as the test substrate is changed from 30 ° C. to 65 ° C. A change in voltage (measurement voltage) with respect to the substrate temperature is shown. Since each luminance has substantially the same temperature characteristic (−0.07 V / ° C.), the light emitter temperature can be measured with low luminance. For this reason, it is possible to prevent the light emission of the temperature measurement EL 100 of the temperature sensor circuit from affecting printing.

  As described above, in the organic EL element, the voltage across the element when a constant current flows is changed according to the temperature, that is, the resistance component is changed according to the temperature, and the resistance component is decreased when the temperature is increased. Since it has characteristics, if the voltage across the element when driven at a constant current is measured, the ambient temperature of the organic EL element can be estimated based on the temperature characteristic as shown in FIG.

  Accordingly, by measuring the voltage (measurement voltage) Vt across the temperature measurement EL 100 when a constant current It is passed through the temperature measurement EL 100, the ambient temperature of the temperature measurement EL 100 can be obtained. If the light emission amount obtained from the optical sensor TFT 92 is corrected by the temperature coefficient based on the obtained temperature, the uniformity of the light emission luminance can be further improved.

  In order to detect such an ambient temperature, the sensor driver 84, which is a constant current driving means for driving the temperature measurement EL 100 of the temperature sensor circuit at a constant current, generally detects, for example, the light amount Sout as shown in FIG. At the same timing, a TEMP signal for applying a constant current It to the temperature measurement EL 100 is supplied, a voltage Vt between both ends of the temperature measurement EL 100 is detected, A / D converted, and output to the head controller 76 as a temperature sensor output. Supply. As described above, the supply of the TEMP signal to the temperature measurement EL 100 is intermittently performed for an extremely short time required for detecting the voltage Vt, and the temperature measurement EL 100 emits light only at this time. Since the light emission luminance when emitting light is also set to be relatively low, the progress of characteristic deterioration of the temperature measurement EL 100 itself can be suppressed.

FIG. 11 is a block diagram of the head controller 76.
The head controller 76 includes a light amount measurement unit 102, a temperature measurement unit 104, a light amount temperature correction unit 106, a light amount comparison unit 108, a correction data storage unit 110, a data driver data transmission unit 112, a select driver timing generation unit 114, and a sensor driver timing generation. Section 116, arbitration control section 118, and sensor selection sections 120 and 122.

  Here, the sensor selection units 120 and 122 correspond to the respective optical sensor outputs supplied from the sensor driver 84 according to the sensor selection given as the printer control signal from the CPU 70 which is a control unit for controlling the entire image forming apparatus and The temperature sensor output is selectively input to the light quantity measurement unit 102 and the temperature measurement unit 104 in the next stage.

  The light quantity measuring unit 102 converts the optical sensor output into light quantity data. The temperature measuring unit 104 is temperature measuring means for detecting temperature from the temperature sensor output. The light amount temperature correction unit 106 is a light amount correction unit that corrects the temperature of the light amount data obtained by the light amount measurement unit 102 based on the detected temperature obtained by the temperature measurement unit 104.

  The light amount comparison unit 108 compares the latest light amount data whose temperature has been corrected by the light amount temperature correction unit 106 with the previous light amount data held in a temporary storage memory (not shown). That is, the detection of the light amount data by the light amount measuring unit 102 is performed by applying a voltage with the same emission luminance when the characteristics of the organic EL element 36 are not changed between the previous time and the current time. The comparison unit 108 compares the previous and present light amount data detected in this way. Here, when there is no difference between the previous light quantity data and the current light quantity data, it indicates that the deterioration of the characteristics of the organic EL element 36 has not progressed between the previous time and this time, and there is a difference between the previous light quantity data and the current light quantity data. Indicates that the deterioration of the characteristics of the organic EL element 36 has progressed between the previous time and the current time. The correction data storage unit 110 stores a correspondence table between the gradation value of the image data in each pixel and the light amount correction data of the data voltage Vdata. In the initial stage, values at the initial stage of the system are stored in advance. The correction data storage unit 110 is configured by a flash ROM or the like that retains data even when the power is turned off and can be rewritten in the system. Thus, the correction data held in the correction data storage unit 110 is subject to deterioration of the characteristics of the organic EL element 36 every time there is a change in the comparison result of the light amount data by the light amount comparison unit 108. Is detected by the light amount comparison unit 108. In determining whether there is a change in the comparison result of the light quantity data in the light quantity comparison unit 108, a predetermined threshold is provided, and it is determined that there is a change when there is a difference between the previous and current light quantity data exceeding the threshold. You may make it do.

  The data driver data sending unit 112 corrects the gradation signal corresponding to the image data with the correction data held in the correction data storage unit 110 and sends it to each data driver 80 as the data voltage Vdata. Thereby, it can control so that it may become a fixed light quantity irrespective of a temperature change.

  In this case, as disclosed in Patent Document 1, light amount correction data for each light emitter is obtained and stored in advance, and sensitivity correction data for each position of the photosensitive drum 10 is also obtained and stored in advance. In addition, based on the stored correction data, the correction data held in the correction data storage unit 110 is further corrected to determine the data voltage Vdata for each light emitter, that is, the organic EL element 36. Can do. Therefore, there is no problem even if a plurality of the photosensor TFTs 92 and temperature measuring ELs 100 are provided corresponding to each organic EL element 36 and not provided for each organic EL element 36.

  The select driver timing generation unit 114 generates a timing signal of each selection signal Vsel generated by each select driver 82 and sends it to each select driver 82.

  The sensor driver timing generator 116 generates a timing signal for setting the timing of each SCG signal, refresh signal RFSH, and TEMP signal generated by each sensor driver 84 and sends the timing signal to each sensor driver 84.

  The arbitration control unit 118 receives the horizontal control signal / HSYNC, the vertical control signal / VSYNC, and each printer control signal from the CPU 70, and receives the sensor driver timing generation unit 116, the select driver timing generation unit 114, and the data. The entire driver data sending unit 112 is monitored and controlled to perform timing arbitration.

  FIG. 12 is a diagram illustrating an operation flowchart of the light amount correction process. At the time of printing, this light amount correction processing is first performed before the actual exposure process is performed.

  That is, the CPU 70 first determines whether or not the current operation mode is set to the correction operation mode (step S10). For example, the correction operation mode may be set manually by the user by a button operation or a menu operation, or a threshold value such as a continuous printing time or a continuous printing number is provided, and when the threshold value is exceeded, automatic operation is performed. Alternatively, automatic setting may be performed so as to shift to the correction operation mode.

  If the correction operation mode is not set, the light amount correction process is terminated and the normal exposure process proceeds. In this case, the data voltage Vdata corresponding to the image data is corrected and used by the correction data of the correction data storage unit 110 rewritten in the initial value or the previous correction operation mode.

  On the other hand, when the correction operation mode is set, the luminance measurement data (in the pixel having the organic EL element 36 of the designated dot) according to the address of the designated dot set in an internal memory or register (not shown) ( Measurement Vdata) is applied to emit light (step S12). In this case, for example, the designated dots are designated in order from the organic EL element 36 on one end side of the organic EL element array. That is, as luminance measurement data, a preset gradation value, for example, low-luminance image data as described above is sent to the data driver data sending unit 112 of the head controller 76, and the data driver data sending unit 112 The data voltage Vdata (measurement Vdata) corrected by the correction data held in the correction data storage unit 110 is supplied to the data driver 80, and the organic EL element 36 corresponding to the designated dot is caused to emit light.

  Then, the sensor driver 84 selects an optical sensor circuit corresponding to the emitted organic EL element 36 (step S14), and asserts the SCG signal and the refresh signal RFSH of the optical sensor circuit (step S16). Thereafter, as shown in FIG. 8, after waiting for the discharge timing of the dark current holding capacitor 98 (step S <b> 18), by performing sensor selection, the sensor selection units 120 and 122 of the head controller 76 are switched to change the light amount measurement unit 102. Thus, the light quantity Sout of the photosensor TFT 92 corresponding to the organic EL element 36 of the designated dot is measured (step S20).

  Next, the sensor driver 84 causes a specified constant current It to flow through the temperature measurement EL 100 corresponding to the organic EL element 36 of the specified dot (step S22), and the temperature measurement unit 104 causes the voltage Vt of the applied voltage TEMP at that time. Is measured to measure the temperature around the temperature measurement EL100 (step S24).

  Then, the light amount temperature correction unit 106 corrects the light emission amount acquired by the light amount measurement unit 102 based on the temperature acquired by the temperature measurement unit 104 using a temperature coefficient (step S26). Here, since the light quantity Sout measured by the light quantity temperature correction unit 106 has a coefficient rather than a linear relationship with respect to the temperature, a table in which the temperature coefficient is previously associated with the measurement data is prepared, and the table of the temperature coefficient is obtained. Use to correct.

  Thereafter, the light quantity comparison unit 108 compares the measurement data thus obtained with the previous measurement data (step S28). Here, if there is no change, that is, if it is detected that the deterioration of the characteristics of the organic EL element 36 has not progressed from the previous time, the address is prepared for the next dot measurement without rewriting the correction data. Is set (step S30).

  On the other hand, when there is a change compared to the previous measurement data, that is, when it is detected that the characteristic deterioration of the organic EL element 36 has progressed from the previous time to the current time, the correction data stored in the correction data storage unit 110 is corrected. Is rewritten to new data (step S32). In the exposure step, the reference value of the image data to be actually printed is corrected by the rewritten correction data, and the corrected print data is sent from the data driver data sending unit 112 to the data driver 80 as the data voltage Vdata. It will be. Then, in preparation for the next dot measurement, an address is set (step S30).

  Then, it is confirmed whether or not there is a dot that has not been processed (step S34). If there is a dot that has not yet been processed, the process returns to step S12.

  Thus, when the processing is completed for all the dots, the light amount correction processing is terminated and the normal exposure process proceeds. In this case, the data voltage Vdata corresponding to the image data is corrected and used by the correction data in the correction data storage unit 110 rewritten in step S32.

  As described above, according to the present embodiment, the optical sensor TFT 92 for light emission luminance compensation of the light emitting element (organic EL element 36) of the organic EL element array is provided, and between both ends of the element when a constant current is passed. The temperature measurement EL100, which is an organic EL element having the same structure as that of the organic EL element 36 used in the light emitting element, is used as a temperature sensor by utilizing the characteristic of the organic EL element that the voltage changes depending on the temperature. The temperature of the light sensor TFT 92 is obtained, the temperature of the light sensor TFT 92 is compensated, and the amount of light emitted from the organic EL element 36 as the light emitting element is corrected. Further, it is possible to make uniform the amount of light irradiated on the photosensitive drum 10 by correcting the change in the light emission luminance due to the deterioration with time and the temperature. Therefore, it is possible to provide an exposure apparatus capable of forming a high-quality image and an image forming apparatus including the exposure apparatus.

  Further, since the temperature measurement EL 100 can be formed simultaneously with the formation of the organic EL element 36 as a light emitting element, temperature measurement can be performed without increasing the number of manufacturing steps.

  Furthermore, since the relationship between the temperature and the light quantity is measured in advance and tabulated, the light quantity value detected by the photosensor TFT 92 can be corrected based on the temperature measured by the temperature measurement EL 100, so that a complicated calculation can be performed. The correction can be easily performed without performing it.

  As mentioned above, although this invention was demonstrated based on one Embodiment, this invention is not limited to one Embodiment mentioned above, Of course, a various deformation | transformation and application are possible within the range of the summary of this invention. It is.

  For example, the optical sensor TFT 92 and the temperature measurement EL 100 are formed on a scale of one for a plurality of light emitting elements (organic EL elements 36), but it goes without saying that they may be provided one-on-one with the light emitting elements. It is.

  Further, the organic EL element array has been described on the assumption that the organic EL elements 36 as the light emitting elements are arranged in a line on the pixel substrate 12. However, the organic EL element array may be in a plurality of lines, and in this case, the organic EL elements 36 may be arranged in a straight line. The arrangement position may be shifted such as a staggered arrangement.

  In the above-described embodiment, the case where the present invention is applied to the organic EL head (exposure unit) of the image forming apparatus has been described. However, the present invention is not limited to this. For example, a plurality of pixels having light emitting elements are provided. You may apply to the light-emitting device arranged and the display apparatus provided with the display panel in which the some pixel which has a light emitting element is arranged two-dimensionally. In this case, for example, the periphery of the temperature measurement EL element may be covered with a light-shielding curtain so that the light emission of the temperature measurement EL element used as the temperature sensor is not visually recognized from the outside.

1 is a diagram illustrating an example of a configuration of an image forming apparatus according to an embodiment of the present invention. It is sectional drawing of the transversal direction of the pixel substrate which shows the basic structure of the organic EL element on a pixel substrate. (A) is a figure which shows the external appearance of an organic EL head, (B) is side sectional drawing of an organic EL head. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus. It is a figure which shows the more detailed structure of a head drive part. It is a figure which shows the circuit structure of an organic electroluminescent panel. It is a figure which shows the timing chart at the time of printing. It is a figure which shows the timing chart at the time of light quantity measurement. It is a figure which shows the planar structure of an organic electroluminescent head. It is a figure which shows the result of having measured the temperature characteristic when organic electroluminescent material was driven by constant current. It is a block block diagram of a head controller. It is a figure which shows the operation | movement flowchart of a light quantity correction process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Photosensitive drum 12 ... Pixel substrate 14 ... Lens array 16 ... Organic EL head 36 ... Organic EL element 38 ... Opposite substrate 40 ... Pixel electrode 42 ... Hole transport layer (HTL)
44 ... Light emitting layer 46 ... Electron transport layer (ETL)
48 ... Counter electrode 50 ... EL layer 60 ... Driver IC
70 ... CPU
72 ... Image processing control circuit 74 ... Head drive unit 76 ... Head controller 78 ... Organic EL panel 80 ... Data driver 82 ... Select driver 84 ... Sensor driver 86 ... Drive TFT
88 ... Selection TFT
90 ... holding capacitor 92 ... optical sensor TFT
94 ... Charge TFT
96 ... Read TFT
98 ... dark current holding capacitor 100 ... temperature measurement EL
DESCRIPTION OF SYMBOLS 102 ... Light quantity measurement part 104 ... Temperature measurement part 106 ... Light quantity temperature correction part 108 ... Light quantity comparison part 110 ... Correction data storage part 112 ... Data driver data transmission part 114 ... Select driver timing generation part 116 ... Sensor driver timing generation part 118 ... Arbitration control unit 120, 122 ... sensor selection unit

Claims (9)

A light emitting unit that has at least one pixel having a light emitting element and emits light according to supplied image data;
A light quantity measuring unit provided corresponding to the light emitting element and having at least one photosensor for detecting the quantity of light emitted from the light emitting element;
A temperature measuring unit provided corresponding to the optical sensor and having at least one temperature sensor for acquiring a temperature in the vicinity of the optical sensor;
The light amount value detected by the optical sensor of the light amount measurement unit is corrected based on the temperature characteristics of the optical sensor and the temperature acquired by the corresponding temperature sensor of the temperature measurement unit, and the corrected A control unit that controls a value of a drive signal supplied to the light emitting unit corresponding to the image data based on a light amount value;
A light-emitting device comprising: The controller is
A first light amount obtained by correcting the light amount of the light emitted from the light emitting element detected at the first timing by the light amount measuring unit based on the temperature acquired by the temperature measuring unit, and the first timing A second timing after a predetermined time has elapsed from the second time after the light amount emitted from the light emitting element detected by the light amount measurement unit is corrected based on the temperature acquired by the temperature measurement unit A light intensity comparison unit for comparing the light intensity;
A correction data storage unit that holds light amount correction data corresponding to a difference between the first light amount and the second light amount by the light amount comparison unit;
A drive signal output unit that corrects a gradation signal corresponding to the image data based on the light amount correction data held in the correction data storage unit and outputs the correction signal as the drive signal;
The light emitting device according to claim 1, comprising:   The said light emitting element in the said light emission part and the said temperature sensor in the said temperature measurement part are comprised by the organic EL element of the same structure formed on the same board | substrate. Light-emitting device.   The temperature measuring unit includes a voltage measuring unit that measures a voltage between both ends of the organic EL element when a constant current is passed through the organic EL element constituting the temperature sensor, and is measured by the voltage measuring unit. The light emitting device according to claim 3, wherein the temperature is acquired based on a value of a measured voltage and a temperature characteristic of the organic EL element.   The control unit includes a temperature coefficient holding unit that tabulates and holds a relationship between a light amount value detected by the optical sensor and the temperature of the optical sensor, and holds the temperature acquired by the temperature measuring unit and the temperature coefficient. The light quantity temperature correction part which correct | amends the value of the light quantity detected by the said optical sensor of the said light quantity detection part based on the value hold | maintained at the part in any one of Claim 1 thru | or 4 characterized by the above-mentioned. The light emitting device described. The light emitting unit has a light emitting element array in which a plurality of the pixels having the light emitting elements are arranged,
The light quantity measuring unit has a plurality of the optical sensors corresponding to each of the one or more light emitting elements,
The temperature measuring unit has a plurality of the temperature sensors corresponding to each of the plurality of optical sensors,
The control unit controls the value of the drive signal supplied to each of the plurality of pixels based on the temperature acquired by each temperature sensor of the temperature measurement unit. The light emitting device according to any one of 5. A drive control method for a light-emitting device that has a light-emitting unit in which at least one pixel having a light-emitting element is arranged and emits light according to supplied image data from the light-emitting element of the light-emitting unit,
Causing the light emitting element of the light emitting unit to emit light, and detecting the amount of light emitted from the light emitting element by an optical sensor;
Obtaining a temperature in the vicinity of the optical sensor by a temperature sensor provided corresponding to the optical sensor;
A light amount value detected by the light sensor is corrected based on a temperature characteristic of the light sensor and a temperature acquired by the temperature sensor, and the light amount value corresponds to the image data based on the corrected light amount value. Controlling the value of the drive signal supplied to the light emitting unit,
A drive control method for a light-emitting device, comprising: The step of controlling the value of the drive signal comprises:
Correcting the light amount of the light emitted from the light emitting element detected by the light sensor at a first timing based on the temperature acquired by the temperature sensor to be a first light amount;
Based on the temperature acquired by the temperature sensor, the amount of light emitted from the light emitting element detected by the optical sensor at a second timing after a predetermined time has elapsed from the first timing. And a step of setting the second light amount,
Comparing the first light quantity and the second light quantity;
Correcting the gradation signal corresponding to the image data based on light amount correction data corresponding to the difference between the first light amount and the second light amount, which is held in advance, and outputting the correction signal as the drive signal; ,
The drive control method of the light-emitting device of Claim 7 characterized by the above-mentioned. The temperature sensor includes an organic EL element having the same structure as the light emitting element,
Obtaining the temperature comprises:
Flowing a constant current through the organic EL element constituting the temperature sensor at the timing of acquiring the temperature; and
Measuring a voltage across the organic EL element when the constant current is passed;
Obtaining the temperature based on the measured voltage value and the temperature characteristics of the organic EL element;
The drive control method of the light-emitting device of Claim 7 or 8 characterized by the above-mentioned.

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