Light emitting device, wearable device, display, photoelectric conversion device, electronic apparatus, illumination device, and movable body

Abstract

To provide a light emitting device advantageous in terms of improving the quality of a light emission image.SOLUTION: A light emitting device comprises: a plurality of light emitting elements; a plurality of conversion circuits provided in correspondence respectively with the plurality of light emitting elements; and a voltage generation unit that generates a plurality of reference voltages. Each of the plurality of conversion circuits converts a digital signal supplied from outside into an analog signal for driving one corresponding light emitting element of the plurality of light emitting elements by using the plurality of reference voltages generated by the voltage generation unit. At least one reference voltage of the plurality of reference voltages is supplied to each of the plurality of conversion circuits from the voltage generation unit through a buffer circuit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a light-emitting device, a wearable device, a display device, a photoelectric conversion device, an electronic device, a lighting device, and a moving object. [Background technology]

[0002] Light-emitting devices using organic EL elements often have a pixel section, consisting of pixels arranged in a matrix, and a driver circuit (specifically, a horizontal driver circuit and a vertical driver circuit) for driving the pixels, integrated into one unit. Light-emitting devices often incorporate a digital interface driver circuit as the horizontal driver, and digital-to-analog converter circuits (hereinafter sometimes referred to as "DA converter circuits") arranged in columns of the driver circuit, such as reference voltage selection DA converters. In a reference voltage selection DA converter, a digital light-emitting signal is converted into an analog signal by selecting a reference voltage for each gradation using a switch. The signal line that transmits the analog light-emitting signal converted by the DA converter to each pixel in the pixel section has capacitance. The DA converter charges and discharges the signal line so that the signal line reaches a predetermined voltage based on the reference voltage selected by the switch. The settling time of the signal line due to charging and discharging affects the display cycle, i.e., the frame rate, of the light-emitting device. Patent Document 1 discloses a technology for shortening this settling time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-191536 Summary of the Invention [Problem to be solved by the invention]

[0004] Factors that cause fluctuations in the potential of a signal line include the potential difference between the signal line and a predetermined reference voltage selected by the DA conversion circuit, and noise associated with DA conversion operations. Examples of such noise include switching noise associated with switch operation and coupling between the signal line and the digital signal on the control line that controls the switch. Similarly, the wiring that supplies the reference voltage selected by the DA conversion operation can also fluctuate. In other words, in order for the signal line to reach a predetermined voltage based on the reference voltage selected by the switch, the signal line and the wiring that supplies the reference voltage must settle.

[0005] Patent Document 1 attempts to shorten charge / discharge times by precharging signal lines to reduce the potential difference between a predetermined reference voltage selected by a DA conversion circuit and the signal line. However, this does not reduce the effects of noise associated with DA conversion operations. In a configuration in which a reference voltage is shared by multiple DA conversion circuits, the same reference voltage may be selected by the multiple DA conversion circuits. In this case, noise may be superimposed on the signal line supplying the reference voltage, compared to the operation of a single DA conversion circuit, and the potential of the signal line supplying the reference voltage may fluctuate significantly. If the selected reference voltage does not have enough time to settle to a predetermined voltage, the DA conversion circuits sharing the reference voltage will not be able to output the predetermined light-emitting signal, resulting in inaccurate lighting. Furthermore, since the settling time depends on the number of DA conversion circuits selecting the same reference voltage, it also depends on the pattern of the light-emitting image and may decrease with an increase in the number of pixels. Sufficient settling time is required to allow the signal line and reference voltage to settle, resulting in a trade-off between frame rate and light-emitting image quality.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a light emitting device that is advantageous in terms of improving the quality of a light emitting image. [Means for solving the problem]

[0007] In order to achieve the above object, one aspect of the present invention provides a light-emitting device comprising a plurality of light-emitting elements, a plurality of conversion circuits each corresponding to the plurality of light-emitting elements, and a voltage generation unit that generates a plurality of reference voltages, wherein each of the plurality of conversion circuits uses the plurality of reference voltages generated by the voltage generation unit to convert a digital signal supplied from outside into an analog signal for driving a corresponding one of the plurality of light-emitting elements, and at least one of the plurality of reference voltages is supplied from the voltage generation unit to each of the plurality of conversion circuits via a buffer circuit.

[0008] Further objects and other aspects of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a light emitting device that is advantageous in terms of improving the quality of a light emitting image. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a configuration example of a light emitting device according to a first embodiment; [Figure 2] FIG. 1 is an equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a first embodiment; [Figure 3] Example of an equivalent circuit for a buffer circuit [Figure 4] Example of an equivalent circuit for a buffer circuit [Figure 5] Example of an equivalent circuit for a buffer circuit [Figure 6] Example of an equivalent circuit for a buffer circuit [Figure 7] Equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to the first embodiment (modification) [Figure 8] FIG. 10 is an equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a second embodiment. [Figure 9] Equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a second embodiment (modification) [Figure 10]FIG. 10 is an equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a third embodiment. [Figure 11] Equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a third embodiment (modification) [Figure 12] FIG. 10 is an equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a fourth embodiment. [Figure 13] FIG. 10 is an equivalent circuit diagram of a voltage generation circuit and a column DAC circuit according to a fifth embodiment. [Figure 14] A diagram explaining the operation timing of each column DAC circuit [Figure 15] 10 is a block diagram showing a light emitting device (first configuration example) according to a sixth embodiment; [Figure 16] 10 is a block diagram showing a light emitting device (second configuration example) according to a sixth embodiment; [Figure 17] 2 is a cross-sectional view showing an example of the configuration of a pixel of the light-emitting device of FIG. 1. [Figure 18] FIG. 1 is a diagram illustrating an example of a display device using a light-emitting device according to each embodiment. [Figure 19] 1 is a diagram showing an example of a photoelectric conversion device using a light-emitting device according to each embodiment; [Figure 20] 1 is a diagram showing an example of an electronic device using a light-emitting device according to each embodiment; [Figure 21] FIG. 1 is a diagram illustrating an example of a display device using a light-emitting device according to each embodiment. [Figure 22] 1 is a diagram showing an example of an illumination device using the light-emitting device of each embodiment; FIG. [Figure 23] 1 is a diagram showing an example of a moving object using a light-emitting device according to each embodiment; [Figure 24] FIG. 1 is a diagram illustrating an example of a wearable device using the light-emitting device of each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] The following describes embodiments of the light emitting device 10 according to the present invention. Note that the following embodiments are merely examples of the present invention, and the present invention is not limited to the numerical values, shapes, materials, components, arrangement and connection of the components, etc.

[0013] First Embodiment A first embodiment of the present invention will be described. FIG. 1 is a block diagram showing an example of the configuration of a light-emitting device 10 of this embodiment. A pixel array 100 (pixel unit) has a plurality of pixels 101 (a plurality of light-emitting elements) arranged two-dimensionally (in a matrix) across a plurality of rows and columns on a substrate. Each pixel 101 receives a control signal from a vertical scanning circuit 200 via a scanning line 210, and receives a luminance signal voltage as an image signal from a signal output circuit 300 via a signal line 310. The vertical scanning circuit 200 and the signal output circuit 300 are controlled by a control circuit 400 (control unit) via a plurality of control lines 410 and 420, respectively. Each pixel 101 has a light-emitting diode (light-emitting element) and emits light at an amount corresponding to the input luminance signal voltage. Each pixel 101 may have a plurality of sub-pixels arranged for each color. In this case, the signal lines 310 are arranged for each column based on each sub-pixel. For example, if one pixel includes three sub-pixels, three signal lines 310 can be arranged in one pixel column.

[0014] The signal output circuit 300 includes a horizontal scanning circuit 301 , a column DAC circuit 302 , and a column driver circuit 303 .

[0015] The horizontal scanning circuit 301 is a transfer circuit that scans image data in one direction (horizontal direction) and transfers the digital signals to each of the plurality of column DAC circuits 302. The horizontal scanning circuit 301 has a plurality of memories that hold the digital signals that are scanned in this one direction and transferred to the plurality of column DAC circuits 302, respectively.

[0016] 1, a plurality of column DAC circuits 302 are provided corresponding to the plurality of pixel columns (plurality of light-emitting elements) in the pixel array 100. That is, a plurality of column DAC circuits 302 are provided, one for each pixel column. Each of the plurality of column DAC circuits 302 is a conversion circuit that uses a plurality of reference voltages to convert a digital signal supplied from the outside (specifically, the horizontal scanning circuit 301) into an analog signal for driving the pixels 101 in a corresponding one of the plurality of pixel columns.

[0017] 1, a plurality of column driver circuits 303 are provided corresponding to the plurality of pixel columns in the pixel array 100. That is, the plurality of column driver circuits 303 are provided so that one column driver circuit 303 corresponds to one column DAC circuit and one pixel column. Each of the plurality of column driver circuits 303 is a drive circuit that drives one corresponding pixel column among the plurality of pixel columns using an analog signal output from a corresponding one of the plurality of column DAC circuits 302. Note that "DAC" is an abbreviation for digital / analog converter.

[0018] In the light emitting device 10 of this embodiment, image data is scanned by a horizontal scanning circuit 301, input to each column DAC circuit 302 via a DAC control signal line 320 for each column, and converted into an analog voltage by each column DAC circuit 302. The analog voltage is input to each column driver circuit 303 as a luminance signal voltage via a DAC output line 330 for each column. Each column driver circuit 303 then inputs the analog signal (luminance signal voltage) input from the column DAC circuit 302 to the pixels 101 (light emitting elements) of each column via a signal line 310, thereby driving the pixels 101 of each column.

[0019] The voltage generation circuit 500 (voltage generation unit) generates a plurality of analog voltages Vref (256 analog voltages when the image data is 8 bits) as a plurality of reference voltages. The plurality of reference voltages generated by the voltage generation circuit 500 are supplied to the signal output circuit 300 via a reference voltage line 510. The voltage generation circuit 500 may also generate a reference voltage used to correct variations in the signal output circuit 300 and the pixels 101. In this case, the reference voltage for correction can be supplied to the pixels 101 via each column driver circuit 303 and the signal line 310.

[0020] 2 shows an equivalent circuit diagram of the voltage generating circuit 500 and the plurality of column DAC circuits 302 in the light emitting device 10 of this embodiment. In FIG. 2, an example is shown in which image data is configured in 8 bits, and identification codes "-1 to 256" are assigned to the column DAC circuit 302, the reference signal line 510, the analog signal Vref, and the buffer circuits 350, 351, and 352. However, in the following description, the identification codes may be omitted in some cases, in which case "-1 to 256" may be understood as a general term.

[0021] The voltage generating circuit 500 has a resistor string 502 consisting of a plurality of resistors R1 to R255 connected in series between two terminals, and generates a plurality of analog voltages Vref-1 to Vref-256 by the resistor string 502 and outputs them to reference voltage lines 510-1 to Vref-256, respectively. A voltage VT is applied to one of the two terminals connected to the resistor string 502 via a buffer circuit 501a, and a voltage VB is applied to the other via a buffer circuit 501b. The voltages VT and VB may be supplied from outside the light emitting device 10 or may be generated inside the light emitting device 10.

[0022] A plurality of analog voltages Vref-1 to 256 (a plurality of reference voltages) generated by the voltage generation circuit 500 are supplied to each of a plurality of column DAC circuits 302 via reference voltage lines 510-1 to 256. The voltage generation circuit 500 and the plurality of column DAC circuits 302 are connected via buffer circuits respectively arranged on the reference voltage lines 510-1 to 256. Each column DAC circuit 302 has a plurality of switches SW to which the analog voltage Vref is respectively supplied, and selects one of the analog voltages Vref according to the image data using the plurality of switches SW. This converts a digital signal input as image data into an analog signal (analog voltage). The plurality of switches SW in each column DAC circuit 302 may be understood to constitute a digital-to-analog converter.

[0023] In the light emitting device 10 of this embodiment, at least one analog voltage Vref of the multiple analog voltages Vref-1 to Vref-256 generated by the voltage generating circuit 500 is supplied from the voltage generating circuit 500 to each of the multiple column DAC circuits 302 via a buffer circuit. The multiple column DAC circuits 302 may include two or more column DAC circuits 302 (e.g., column DAC circuits 302-1 to 302-4) to which the at least one analog voltage Vref is supplied via a common buffer circuit. In the example of FIG. 2, the analog voltage Vref is supplied to each of the column DAC circuits 302-1 to 302-4 (first group of conversion circuits) via a common buffer circuit 350 (first buffer circuit). The analog voltage Vref is supplied to each of the column DAC circuits 302-5 to 302-8 (second group of conversion circuits) via a common buffer circuit 351 (second buffer circuit). The analog voltage Vref is supplied to each of the column DAC circuits 302 subsequent to the column DAC circuit 302-8 via a common buffer circuit 352. Buffer circuits 350 to 352 are connected in series, and the output of buffer circuit 350 is input to buffer circuit 351, and the output of buffer circuit 351 is input to buffer circuit 352.

[0024] Here, we will explain the operation of a light-emitting device 10 that does not include a buffer circuit. During operation of the column DAC circuit 302, the analog voltage Vref selected by the switch SW transiently fluctuates due to factors such as the potential difference with the DAC output line 330, switching noise caused by the operation of the switch SW, and coupling with the DAC control signal line 320 that controls the switch. For the reference voltage line 510 to settle to a predetermined analog voltage Vref, a response time is required based on a time constant determined by factors such as the resistance value of the resistor string 502, the wiring parasitic resistance and wiring parasitic capacitance of the reference voltage line 510, and the input parasitic capacitance of the column driver circuit 303. Furthermore, because the analog voltage Vref is shared by multiple column DAC circuits 302, the same analog voltage Vref may be simultaneously selected by multiple column DAC circuits 302 depending on the image data. The greater the number of column DAC circuits 302 simultaneously selecting the same analog voltage Vref, the greater the transient potential fluctuations associated with the DA conversion operations of the column DAC circuits 302. The input parasitic capacitance of the column driver circuit 303 also increases by the number of columns. This can increase the required settling time. If sufficient settling time is not provided, this can be a factor in preventing accurate light emission based on image data. It can also prevent accurate light emission across multiple column DAC circuits 302 that select the same analog voltage Vref. For example, horizontal stripes and horizontal smears, typically caused by crosstalk between the column DAC circuits 302, may be observed. These issues degrade the quality of the emitted light image.

[0025] In the light-emitting device 10 of this embodiment, the analog voltage Vref is supplied to each column DAC circuit 302 via a buffer circuit 350 arranged on the reference voltage line 510. This configuration reduces the time constant of each resistance compared to when the analog voltage Vref is directly supplied to each DAC circuit 302 from the voltage generation circuit 500 (resistor string 502). Furthermore, the wiring parasitic resistance and wiring parasitic capacitance of the reference voltage line 510 and the input parasitic capacitance of the column driver circuit 303 are driven by the buffer circuit 350. Therefore, compared to when the buffer circuit 350 is not arranged, transient fluctuations in the analog voltage Vref caused by the operation of the column DAC circuit 302 are reduced, and the settling time can be shortened. In the light-emitting device 10 of this embodiment, as shown in FIG. 2 , buffer circuits 351-352 are arranged for each of four column DAC circuits 302, thereby reducing the load on each buffer circuit and further shortening the settling time. Furthermore, by arranging buffer circuits between columns, crosstalk between columns can be reduced. 2, a buffer circuit 351 is arranged between the column DAC circuits 302-1 to 302-4 and the column DAC circuits 302-5 to 302-8. By providing this buffer circuit 351, even if a transient potential fluctuation occurs in the reference voltage line 510 connected to the column DAC circuits 302-5 to 302-8, the propagation of the transient potential fluctuation to the reference voltage line 510 connected to the column DAC circuits 302-1 to 302-4 is suppressed. In other words, crosstalk between the column DAC circuits 302-1 to 302-4 and the column DAC circuits 302-5 to 302-8 can be reduced.

[0026] Next, configuration examples of buffer circuits used in the light emitting device 10 of this embodiment will be described. FIGS. 3 to 5 show equivalent circuit examples of buffer circuits 350 to 352 or buffer circuits 501a to 501b. FIG. 3 shows an example in which a buffer circuit is configured by a source follower composed of an NMOS transistor M1 and a current source C1. FIG. 4 shows an example in which a buffer circuit is configured by a source follower composed of a PMOS transistor M2 and a current source C2. FIG. 5 shows an example in which a buffer circuit is configured by a unity gain buffer, which is a differential amplifier circuit composed of NMOS transistors M3 to M4, PMOS transistors M5 to M6, and a current source C3, and which has its inverting input terminal and output terminal shorted. While FIGS. 3 to 5 show a configuration example of buffer circuit 350 as a representative example, similar configuration examples can also be adopted for the other buffer circuits 351 to 352 and 501a to 501b.

[0027] The selection and / or placement of the buffer circuits shown in FIGS. 3 to 5 may be determined based on, for example, the input / output range corresponding to the DC level of the analog voltage Vref, the allowable layout area, power consumption, input / output impedance, etc. Different configurations may be applied to the buffer circuits 350-1 to 350-256, or different configurations may be applied to the buffer circuits 350 to 352. For example, when the input / output levels of each buffer circuit are to be aligned with respect to the analog voltage Vref, the unity gain buffer shown in FIG. 5 may be applied (selected) as the buffer circuit. As another example, when the analog voltage Vref is level-shifted for use, the source follower shown in FIG. 3 or FIG. 4 may be applied (selected) as the buffer circuit. In this case, the source follower shown in FIG. 3 may be applied to the buffer circuit 350, and the source follower shown in FIG. 4 may be applied to the buffer circuit 351, thereby performing different level shifts for each buffer circuit. Alternatively, the source follower shown in FIG. 3 or FIG. 4 may be applied to the buffer circuit 350, and the unity gain buffer shown in FIG. 5 may be applied to the buffer circuit 351.

[0028] Furthermore, even if the buffer circuits have the same configuration, the size of the MOS transistors and the current values ​​of the current sources may be adjusted and applied (placed) depending on the noise and required driving power. For example, assume that the configuration of FIG. 3 is applied to buffer circuits 501a-501b and 350-352. In this case, to achieve low noise and high driving power in buffer circuit 501, it is preferable to increase the gate width of the NMOS transistors and / or increase the current value of current source C1 compared to buffer circuit 350. Furthermore, from the perspective of reducing noise in buffer circuit 350, it is preferable to increase the power (e.g., the current value of the current source) of buffer circuit 350 compared to the power of buffer circuit 351. It is also preferable to increase the area (e.g., the gate width) of buffer circuit 350 compared to the area of ​​buffer circuit 351. This allows the noise of buffer circuit 350 to be smaller than the noise of buffer circuit 351.

[0029] Here, the image data transmitted by the horizontal scanning circuit 301 is so-called digital data. A buffer circuit used to transmit such digital data can be configured, for example, as shown in FIG. 6, with an inverter including an NMOS transistor M7 and a PMOS transistor M8. That is, the buffer circuit can be configured as shown in FIGS. 3 to 5 or as shown in FIG. 6, depending on whether the signal to be buffered is an analog signal or a digital signal. If the signal to be buffered is an analog signal, the configurations shown in FIGS. 3 to 5 are applied to the buffer circuit in order to transmit a specific DC level. On the other hand, if the signal to be buffered is a digital signal, the configuration shown in FIG. 6 is applied to the buffer circuit in order to transmit a signal that swings between the power supply VDD and the ground VSS. In this embodiment, the configurations shown in FIGS. 3 to 5 are applied to the buffer circuit used to transmit the analog voltage Vref, and the configuration shown in FIG. 6 is applied to the buffer circuit used to transmit image data, which is digital data.

[0030] Each buffer circuit can be designed, for example, from the following perspectives. In the case of a buffer circuit transmitting an analog signal (configuration shown in FIGS. 3 to 5), the size of the MOS transistor and the current value of the current source can be determined, for example, to reduce noise. On the other hand, in the case of a buffer circuit transmitting a digital signal (configuration shown in FIG. 6), the size of the MOS transistor can be determined, for example, depending on the transmission frequency and the load of the next stage. Furthermore, the value of the power supply VDD in FIGS. 3 to 6 can be determined depending on the dynamic range of the analog signal when buffering an analog signal, or depending on the transmission speed and power when buffering a digital signal. Furthermore, the arrangement period of the buffer circuits can be determined depending on the settling time when a transient potential fluctuation occurs in the case of an analog signal, or depending on the transmission speed in the case of a digital signal. In the example shown in FIG. 2, buffer circuits 350 to 352 that buffer an analog signal (analog voltage Vref) are arranged for every four columns of column DAC circuits 302 (i.e., at a four-column period).

[0031] Next, the power supply connections of the buffer circuits and the like will be described. The voltage generation circuit 500, the buffer circuits 350-352, and the column DAC circuit 302 may be connected to different power supplies, or may share at least some of the power supplies. The buffer circuits 350-1 to 356 may be connected to the same power supply or different power supplies. For example, the voltage generation circuit 500 and the buffer circuits 350-352 may share the same power supply, while the column DAC circuit 302 may share a power supply different from the voltage generation circuit 500 and the buffer circuits 350-352. In the column DAC circuit 302, switching noise associated with DAC operation can cause transient potential fluctuations in the power supply connected to it. On the other hand, the voltage generation circuit 500 and the buffer circuits 350-352 are connected to a DC power supply, so transient power supply fluctuations are relatively small. That is, by separating the power supplies of the voltage generating circuit 500 and the buffer circuits 350 to 352 from the power supply of the column DAC circuit 302, it is possible to reduce the influence of transient power supply fluctuations caused by the operation of the column DAC circuit 302 on other circuits. Here, connecting a DC power supply may mean applying a DC voltage.

[0032] One example of a power supply connection configuration for reducing the influence of transient power supply fluctuations accompanying the operation of the column DAC circuit 302 on other circuits is to use the same power supply for the buffer circuits 350-352 provided in common for one analog voltage Vref. Alternatively, different power supplies may be used for the buffer circuits 350-352 provided for one analog voltage Vref and the buffer circuits 350-352 provided for other analog voltages Vref. The same power supply may be used for the buffer circuits 350-352 provided for one analog voltage Vref and the column DAC circuit 302. Different power supplies may be used for the voltage generation circuit 500 and the buffer circuits 350-352. Note that the power supply connection relationship is not limited to the example configuration described above.

[0033] Next, a modified example of the light emitting device 10 of this embodiment will be described. FIG. 7 shows an equivalent circuit diagram of a voltage generating circuit 500 and a plurality of column DAC circuits 302 in a modified example of the light emitting device 10 of this embodiment. In the example of FIG. 7, buffer circuits 351-255-256 and buffer circuit 352-255 are not provided, as compared to the example of FIG. 2. Specifically, for analog voltages Vref-1-2 (first reference voltages), buffer circuits 350-1-2, 351-1-2, and 352-1-2 are provided common to a first number of column DAC circuits 302 (four column periods in FIG. 7). On the other hand, for analog voltage Vref-256 (second reference voltage), buffer circuits 350-256 and 352-256 are provided common to a second number of column DAC circuits 302 (eight column periods in FIG. 7), which is different from the first number. Furthermore, for the analog voltage Vref-255, a common buffer circuit 350-255 is provided for each of the column DAC circuits 302 whose number is different from the first number and the second number.

[0034] For example, when analog voltage Vref-255 is selected at a luminance level at which the influence of transient fluctuations accompanying the operation of column DAC circuit 302 is less noticeable (e.g., during daylight hours), only buffer circuits 350-255 are arranged on reference voltage line 510-255, prioritizing area and power savings. Also, when analog voltage Vref-256 is selected at a luminance level at which the influence of transient fluctuations accompanying the operation of column DAC circuit 302 is less noticeable, but crosstalk between column DAC circuits is particularly desired to be reduced, buffer circuits are arranged on reference voltage line 510-256 in a thinned-out manner. That is, buffer circuits 350-256 and 352-256 are arranged on reference voltage line 510-256 in FIG. 7 in a thinned-out manner to an eight-column period, compared to the four-column period in FIG. 2. This standard example of buffer circuit arrangement is merely an example, and the number and arrangement period of each buffer are determined appropriately depending on the layout area, power, and other criteria. 7 shows an example of a configuration in which buffer circuits 351-255 to 256 and buffer circuits 352-255 are not physically arranged, but the present invention is not limited to this. For example, a configuration in which buffer circuits are physically arranged but the buffer circuits are equipped with a power saving function and an input / output through function, and the buffer circuits are switched between being used and not being used depending on the operation mode may be used.

[0035] Next, we will explain the variations in the characteristics and emission brightness of each buffer circuit. For example, if the buffer circuits are configured as source followers as shown in FIG. 3, variations in the threshold of the NMOS transistor M1 and variations in the current value of the current source C1 can cause differences in the level shift amount between the buffer circuits 350-1 to 350-256 and between the buffer circuits 350-352. Random variations in the level shift amount result in errors in the emission brightness relative to the image data. For example, in the example of FIG. 2, this results in differences in linearity with respect to the image data for every four columns, which is the arrangement period of the buffer circuits. As a result, the emitted image may exhibit brightness steps every four columns, differences in color reproducibility, and other degradation in the quality of the emitted image. Therefore, each buffer circuit may be equipped with an output offset adjustment function and a threshold correction function. Furthermore, a correction drive period may be set to acquire correction parameters from the emitted image and correct (adjust) each buffer circuit based on the correction parameters. Alternatively, a correction mechanism may be provided in the column DAC circuit 302 or the column driver circuit 303. Alternatively, the image data may be corrected by the control circuit 400 by referring to the correction parameters obtained during the correction drive period.

[0036] As described above, in the light emitting device 10 of this embodiment, at least one of the multiple analog voltages Vref shared by the multiple column DAC circuits 302 is supplied from the voltage generation circuit 500 to each column DAC circuit 302 via a buffer circuit. This configuration can reduce crosstalk between the column DAC circuits 302 via the reference voltage line 510 that occurs when the column DAC circuits 302 operate. Furthermore, since the amount of transient fluctuation in the analog voltage Vref is reduced and the required settling time is also shortened, the quality of the emitted light image can be improved without depending on an increase in the number of pixels or the image pattern.

[0037] Second Embodiment A second embodiment of the present invention will be described. This embodiment basically follows on from the first embodiment, and can follow the first embodiment except for the matters mentioned below.

[0038] 8 shows an equivalent circuit diagram of the voltage generating circuit 500 and the plurality of column DAC circuits 302 in the light emitting device 10 of this embodiment. In this embodiment, compared to the configuration example of the first embodiment, resistor strings 520 to 522 (second resistor strings) are provided between the outputs of the buffer circuits 350 to 352. The following description will focus on the differences from the first embodiment.

[0039] In the first embodiment, a plurality of analog voltages Vref generated by the voltage generation circuit 500 are supplied to each column DAC circuit 302 via each buffer circuit 350-352. On the other hand, in the present embodiment, buffer circuits 350-352 are provided for each of the reference voltage lines 510-1, 256, and resistor strings 520-522 are provided between the outputs of each buffer circuit 350-352. Then, a plurality of voltages generated by each resistor string 520-522 are supplied to each column DAC circuit 302.

[0040] 8, analog voltages Vref-1 and Vref-256 are output from a voltage generating circuit 500. Resistor strings 520 to 522 are connected in parallel between the output terminal of the analog voltage Vref-1 (first reference voltage) and the output terminal of the analog voltage Vref-256 (second reference voltage). Each resistor string 520 to 522 is made up of a plurality of resistors R1 to R255 connected in series between the output terminal of the analog voltage Vref-1 and the output terminal of the analog voltage Vref-256.

[0041] The resistor string 520 is connected between two reference voltage lines 510-1 and 256 and generates a plurality of voltages (analog voltages) that are supplied to each of the column DAC circuits 302-1 to 302-4. The resistor string 520 is supplied with analog voltages Vref-1 and 256 from the voltage generation circuit 500 via buffer circuits 350-1 and 256. Similarly, the resistor string 521 is connected between two reference voltage lines 510-1 and 256 and generates a plurality of voltages (analog voltages) that are supplied to each of the column DAC circuits 302-5 to 302-8. The resistor string 521 is supplied with analog voltages Vref-1 and 256 from the voltage generation circuit 500 via buffer circuits 351-1 and 256. The resistor string 522 is connected between two reference voltage lines 510-1 and 256 and generates a plurality of voltages (analog voltages) that are supplied to each of the column DAC circuits 302 subsequent to the column DAC circuit 302-8. The resistor string 522 is supplied with analog voltages Vref-1, 256 from the voltage generating circuit 500 via buffer circuits 352-1, 256.

[0042] As explained in the first embodiment, variations in the characteristics of each buffer circuit can affect the quality of the emitted image. Therefore, in this embodiment, buffer circuits are provided only for the analog voltages Vref-1 and Vref-256. The multiple voltages generated by the resistor strings 520 to 522 provided between the outputs of these buffer circuits are determined by the resistance ratios of the multiple resistors R1 to R255 that make up the resistor string. Therefore, linearity with respect to image data can be improved compared to the first embodiment. Furthermore, by adjusting the resistance values ​​and layout area of ​​the resistor strings, power and area can be reduced compared to the configuration of the first embodiment in which a buffer circuit is provided for each of the multiple reference voltage lines 510.

[0043] Fig. 9 shows a modified example of the light emitting device 10 of this embodiment. In the example of Fig. 9, compared to the example of Fig. 8, each of the resistor strings 520 to 522 is connected between two reference voltage lines 510-2 and 510-256. Each of the resistor strings 520 to 522 is made up of a plurality of resistors R2 to R255 connected in series between the output terminal of the analog voltage Vref-2 and the output terminal of the analog voltage Vref-256.

[0044] The resistor string 520 is supplied with analog voltages Vref-2, 256 from the voltage generation circuit 500 via buffer circuits 350-2, 256. Each of the column DAC circuits 302-1 to 302-4 is supplied with a plurality of voltages (analog voltages) generated by the resistor string 520, and is also supplied with an analog voltage Vref-1 from the voltage generation circuit 500 via the buffer circuit 350-1. Similarly, the resistor string 521 is supplied with analog voltages Vref-2, 256 from the voltage generation circuit 500 via buffer circuits 351-2, 256. Each of the column DAC circuits 302-5 to 302-8 is supplied with a plurality of voltages (analog voltages) generated by the resistor string 521, and is also supplied with an analog voltage Vref-1 from the voltage generation circuit 500 via the buffer circuit 351-1.

[0045] 8 and 9, it is possible to reduce crosstalk between the column DAC circuits 302 that share the multiple analog voltages generated by the resistor strings 520 to 522. However, crosstalk may occur between the multiple analog voltages via the resistors that make up the resistor strings 520 to 522. In FIG. 9, for the multiple analog voltages supplied to the column DAC circuits 302, the analog voltage Vref-1 that is frequently selected in each column DAC circuit 302 is separated from the other voltages, thereby reducing mutual influence. This makes it possible to reduce crosstalk between the multiple analog voltages.

[0046] As described above, in the light emitting device 10 of this embodiment, the resistor strings 520-522 are arranged between the outputs of the buffer circuits, and multiple analog voltages generated by each of the resistor strings 520-522 are supplied to each column DAC circuit 302. This configuration achieves the same effects as the first embodiment and also suppresses degradation of the quality of the emitted image caused by variations in the characteristics of each buffer circuit. Furthermore, according to the configuration example of FIG. 9, crosstalk between the multiple analog voltages is easily reduced, thereby further improving the quality of the emitted image compared to the first embodiment.

[0047] <Third embodiment> A third embodiment of the present invention will be described. This embodiment basically follows the first embodiment, and can follow the first embodiment except for the matters mentioned below. In addition, the second embodiment may also be applied to this embodiment.

[0048] 10 shows an equivalent circuit diagram of the voltage generation circuit 500 and the plurality of column DAC circuits 302 in the light emitting device 10 of this embodiment. In this embodiment, the plurality of analog voltages Vref generated by the voltage generation circuit 500 are supplied to the column DAC circuits 302 via buffer circuits 353 to 354 connected in parallel. The following description will focus on the differences from the first embodiment.

[0049] In the first embodiment, a configuration has been described in which a plurality of analog voltages Vref generated by a voltage generation circuit 500 are sequentially supplied to each column DAC circuit 302 via buffer circuits 350 to 352 arranged in series on a reference voltage line 510. For example, in the example of FIG. 2 , the output of the voltage generation circuit 500 is connected to the input of the buffer circuit 350, and the output of the buffer circuit 350 is connected to each of the column DAC circuits 302-1 to 302-4 and also to the input of the buffer circuit 351. Similarly, the output of the buffer circuit 351 is connected to each of the column DAC circuits 302-5 to 302-8 and also to the input of the buffer circuit 352. This configuration is referred to as "arranging buffer circuits in series."

[0050] 10, the analog voltage Vref generated by the voltage generating circuit 500 is supplied to each column DAC circuit 302 via buffer circuits 353 to 354 arranged in parallel on a reference voltage line 510. The common reference voltage line 510 is connected to the inputs of the buffer circuits 353 to 354, the output of the buffer circuit 353 is connected to the column DAC circuits 302-1 to 302-4, and the output of the buffer circuit 354 is connected to the column DAC circuits 302-5 to 302-8. This configuration is referred to as "arranging buffers in parallel."

[0051] In the configuration of this embodiment, the multiple column DAC circuits 302 may include two or more column DAC circuits 302 (e.g., column DAC circuits 302-1 and 302-5) to which at least one analog voltage Vref is supplied via different buffer circuits. In the example of FIG. 10, analog voltages Vref-1 to Vref-256 are supplied to the column DAC circuits 302-1 to 302-4 (first group of conversion circuits) via buffer circuits 353-1 to 356 (third buffer circuits), respectively. Then, analog voltages Vref-1 to Vref-256 are supplied to the column DAC circuits 302-5 to 302-8 (second group of conversion circuits) via buffer circuits 354-1 to 354 (fourth buffer circuits), respectively. The buffer circuits 353 to 354 are connected in parallel.

[0052] In the configuration of the first embodiment (e.g., the example of FIG. 2 ), the settling time of transient potential fluctuations in the analog voltage Vref on the reference voltage line 510 caused by the operation of the column DAC circuit 302 can be shortened by a buffer circuit (e.g., the buffer circuit 350) arranged on the reference voltage line 510. In the configuration of this embodiment, the buffer circuits 353 and 354 are arranged in parallel, thereby reducing the impact on the analog voltage Vref on the reference voltage line 510 caused by the operation of the multiple column DAC circuits 302. In other words, the transient potential fluctuations in the analog voltage Vref caused by the operation of the multiple column DAC circuits 302 are suppressed, thereby reducing crosstalk between the column DAC circuits 302. Furthermore, in a configuration in which multiple buffer circuits are arranged in series as in the first embodiment, noise and offsets from the buffer circuits may be superimposed on the analog voltage Vref, thereby degrading the quality of the emitted image. In this embodiment, by arranging the buffer circuits in parallel, degradation of the quality of the emitted image caused by noise and offsets from the buffer circuits can be reduced compared to a configuration in which the buffer circuits are arranged in series.

[0053] Next, a modified example of the light emitting device 10 of this embodiment will be described. FIG. 11 shows an equivalent circuit diagram of a voltage generating circuit 500 and a plurality of column DAC circuits 302 in a modified example of the light emitting device 10 of this embodiment. The configuration of FIG. 11 is obtained by adding (applying) the configuration of the first embodiment (FIG. 2) to the configuration of FIG. 10 described above. That is, in the configuration of FIG. 11, buffer circuits 350-352 arranged in series and buffer circuits 353-354 arranged in parallel are provided on the reference voltage line 510. This configuration can reduce the effect of the operation of the column DAC circuit 302 on the analog voltage Vref on the reference voltage line 510 and shorten the settling time of transient potential fluctuations of the analog voltage Vref. Note that the number and arrangement period of each buffer circuit can be adjusted as appropriate, as described in the first embodiment.

[0054] As described above, in the light emitting device 10 of this embodiment, a plurality of analog voltages Vref are supplied to each column DAC circuit 302 via buffer circuits arranged in parallel on the reference voltage line 510. With this configuration, the same effects as in the first embodiment can be obtained, and crosstalk between the column DAC circuits 302 that occurs due to the operation of the plurality of column DAC circuits 302 can be reduced.

[0055] <Fourth embodiment> A fourth embodiment of the present invention will be described. This embodiment basically follows the first embodiment, and may follow the first embodiment except for the matters mentioned below. In addition, the second embodiment and / or the third embodiment may be applied to this embodiment.

[0056] 12 shows an equivalent circuit diagram of the voltage generation circuit 500 and the plurality of column DAC circuits 302 in the light emitting device 10 of this embodiment. In this embodiment, a voltage generation circuit 500 is provided for each of the plurality of column DAC circuits 302. The following description will focus on the differences from the first embodiment.

[0057] In the first embodiment, a configuration has been described in which multiple analog voltages Vref output from one voltage generation circuit 500 are supplied to multiple column DAC circuits 302 via buffer circuits arranged on a reference voltage line 510. That is, in the first embodiment, one voltage generation circuit 500 is shared by multiple groups of column DAC circuits 302. In contrast, in the present embodiment, a voltage generation circuit 500 and a buffer circuit 350 are individually arranged for each group of column DAC circuits 302. Specifically, a voltage generation circuit 500 and a buffer circuit 350 are individually arranged for a first group of column DAC circuits 302-1 to 302-4 and a second group of column DAC circuits 302-5 to 302-8. This allows the reference voltage line 510 to be separated for each group of column DAC circuits 302, thereby reducing crosstalk between the column DAC circuits 302 that occurs during operation of the multiple column DAC circuits 302.

[0058] Here, arranging multiple voltage generation circuits 500 refers to arranging multiple voltage generation circuits 500 corresponding to multiple column DAC circuits 302 arranged extending in one direction. For example, when the block diagram in FIG. 1 shows the physical arrangement of each component, the signal output circuit 300 is arranged below and to one side of the pixel array 100, and multiple column DAC circuits 302 are arranged in the column direction. This arrangement across the column direction is referred to as "arranging extending in one direction." Meanwhile, as another configuration example of FIG. 1, a signal output circuit 300 and a corresponding voltage generation circuit 500 may also be arranged above the pixel array 100. In this case, two voltage generation circuits 500 are arranged above and below the pixel array 100, but in this embodiment, this is not expressed as "arranging multiple voltage generation circuits 500." In this embodiment, this is expressed as "one voltage generation circuit 500 arranged independently for each signal output circuit 300." In this embodiment, the voltage generation circuit 500 is arranged for every four columns of column DAC circuits 302, but the voltage generation circuit 500 may be arranged for each column, or the voltage generation circuit 500 may be arranged for every column DAC circuit 302 with a different number of columns.

[0059] Furthermore, the voltages VT and VB supplied to each of the multiple voltage generation circuits 500 may be supplied from a signal line common to the multiple voltage generation circuits 500, or may be supplied from different signal lines. Furthermore, the voltages VT and VB may be configured to be supplied between the multiple voltage generation circuits 500 via buffer circuits.

[0060] As described above, in the light emitting device 10 of this embodiment, a voltage generation circuit 500 is provided for each group of column DAC circuits 302. This configuration not only provides the same effects as in the first embodiment, but also reduces crosstalk between the column DAC circuits 302 that occurs when the multiple column DAC circuits 302 operate.

[0061] Fifth Embodiment A fifth embodiment of the present invention will be described. This embodiment basically follows the first embodiment, and may follow the first embodiment except for the matters mentioned below. In addition, the second, third, and / or fourth embodiments may also be applied to this embodiment.

[0062] FIG. 13 shows an equivalent circuit diagram of the voltage generation circuit 500 and the plurality of column DAC circuits 302 in the light emitting device 10 of this embodiment. In this embodiment, the arrangement of the voltage generation circuit 500, the plurality of column DAC circuits 302, and the buffer circuits 350 to 352 is the same as in the first embodiment (FIG. 2). However, in each column DAC circuit 302 of this embodiment, in addition to a digital-to-analog converter, a holding circuit is provided that temporarily holds the plurality of analog voltages Vref supplied from the voltage generation circuit 500. As described above, the digital-to-analog converter is composed of the plurality of switches SW, and converts a digital signal into an analog signal using the plurality of analog voltages Vref held in the holding circuit. Furthermore, the holding circuit can be composed of switches SWH and holding capacitances CH. The following description will focus on the differences from the first embodiment.

[0063] In the light emitting device 10 of this embodiment, a plurality of pairs each including a switch SWH and a holding capacitor CH are provided as holding circuits in each column DAC circuit 302. The plurality of pairs each including a switch SWH and a holding capacitor CH are arranged corresponding to the plurality of analog voltages Vref, that is, corresponding to the plurality of switches SW. Each switch SWH of the holding circuit can be controlled by the control circuit 400 via a control line 420. In each column DAC circuit 302 configured in this manner, the plurality of analog voltages Vref supplied from the voltage generating circuit 500 via a reference voltage line 510 can be temporarily held in the holding capacitor CH.

[0064] FIG. 14 is a diagram illustrating the operation timing of each column DAC circuit 302 in FIG. 13. FIG. 14 illustrates the horizontal synchronization signal, which is the row scanning cycle, the timing of switching between image data D1 and image data D2, the operation timing of the switch SWH, and the operation timing of the switch SW. The switches SWH and SW are on when the control signal is high and off when the control signal is low. In operation per row, the switch SW is controlled based on the image data D1 of the previous row. After the switch SW is turned off, the switch SWH is turned on to connect the storage capacitor CH to the reference voltage line 510. When the switch SWH is turned off, the analog voltage Vref is stored in the storage capacitor CH. After the analog voltage Vref is stored in the storage capacitor CH, the switch SW is controlled (turned on) based on the image data D2. This operation disconnects the reference voltage line 510 and the storage capacitor CH when the switch SW is on. Therefore, even when the same analog voltage Vref is selected between the column DAC circuits 302, crosstalk between the column DAC circuits 302 can be reduced. This reduces the dependency of the settling time of transient potential fluctuations accompanying the operation of the column DAC circuit 302 on an increase in the number of pixels and on the image pattern, thereby reducing the impact on quality degradation of the emitted image. Note that the capacitance value of the storage capacitor CH can be set taking into account an allowable time constant as one index.

[0065] 14 is, for example, power control of the buffer circuits 350 to 352, with the low period indicating power-off and the high period indicating power-on. For example, as shown in FIG. 14, during the period in which the analog voltage Vref is held in the storage capacitor CH (i.e., the period in which the switch SWH is turned off), the buffer circuits 350 to 352 are powered off (i.e., the operation of the buffer circuits 350 to 352 is stopped). This allows the power consumption of the light emitting device 10 to be reduced.

[0066] In the present embodiment, an example has been described in which a holding circuit is provided for each of the plurality of analog voltages Vref supplied from the voltage generating circuit 500 for each column DAC circuit 302, but the present invention is not limited to this. For example, a holding circuit may be provided for only at least one analog voltage Vref among the plurality of analog voltages Vref for each DAC circuit 302.

[0067] As described above, in the light emitting device 10 of this embodiment, each column DAC circuit 302 is provided with a holding circuit that temporarily holds a plurality of analog voltages Vref supplied from the voltage generating circuit 500. Then, in each column DAC circuit 302, the analog voltage Vref supplied via a buffer circuit on the reference voltage line 510 is held in the holding capacitance CH, and then the analog voltage Vref is selected based on the image data (i.e., the digital signal is converted into an analog signal). This configuration not only provides the same effects as in the first embodiment, but also reduces crosstalk between the column DAC circuits 302 via the reference voltage line 510 that occurs when the column DAC circuits 302 operate.

[0068] Sixth Embodiment A sixth embodiment of the present invention will be described. In this embodiment, correction of the light emission luminance of each of a plurality of pixels 101 (light emitting elements) will be described. This embodiment basically follows on from the first embodiment, and can follow the first embodiment except for the matters mentioned below. In addition, the second, third, fourth and / or fifth embodiments may be applied to this embodiment.

[0069] FIG. 15(a) is a block diagram showing a light emitting device 10A according to a first exemplary configuration of the present embodiment. The light emitting device 10A according to the first exemplary configuration shown in FIG. 15(a) further includes a first detector 601, as compared to the light emitting device 10 according to the first exemplary embodiment shown in FIG. 1. The first detector 601 detects the luminance of each of the pixels 101 (light emitting elements). The first detector 601 may detect the luminance of each of the pixels 101 during a calibration period of the light emitting device 10A. Each of the buffer circuits provided in the light emitting device 10A includes an output offset adjustment mechanism 600. As an example, FIG. 15(b) shows a configuration example of a buffer circuit 350 configured as a source follower of FIG. 3. The output offset adjustment mechanism 600 of the buffer circuit 350 may be configured to adjust (change) the output of the buffer circuit 350 by adjusting (changing) the current value of the current source C1. This allows the control circuit 400 to control the output of the buffer circuit 350 using the output offset adjustment mechanism 600 so that the emission brightness of each pixel 101 is corrected (for example, so that it falls within an acceptable range) based on the detection result of the first detection unit 601.

[0070] FIG. 16 is a block diagram illustrating a light-emitting device 10B according to a second exemplary configuration of this embodiment. The light-emitting device 10B according to the second exemplary configuration illustrated in FIG. 16 further includes a second detector 602, as compared with the light-emitting device 10 according to the first exemplary embodiment illustrated in FIG. 1. The second detector 602 detects output offset values ​​between the buffer circuits included in the light-emitting device 10B. The second detector 602 may detect the output offset values ​​during a calibration period for the light-emitting device 10B. Each of the buffer circuits includes an output offset adjustment mechanism 600, as described above with reference to FIG. 15(b). Based on the detection results of the second detector 602, the control circuit 400 can control the output of each buffer circuit using the output offset adjustment mechanism 600 so that the output offset values ​​between the buffer circuits are corrected (e.g., within a tolerance range). This corrects the luminance of each pixel 101. In addition, in the light emitting device 10B of the second configuration example, a first detection unit 601 may be further provided as in the light emitting device 10A of the first configuration example, and the light emission brightness of each pixel 101 may be corrected based on the detection result of the first detection unit 601.

[0071] [Configuration of organic light-emitting element] The organic light-emitting element is provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, a microlens, etc. may be provided on the cathode. When a color filter is provided, a planarizing layer may be provided between the protective layer and the color filter. The planarizing layer may be made of an acrylic resin, etc. The same applies when a planarizing layer is provided between the color filter and the microlens.

[0072] [substrate] Examples of the substrate include quartz, glass, silicon wafer, resin, and metal. The substrate may also include switching elements such as transistors and wiring patterns, with an insulating layer provided thereon. The insulating layer may be made of any material as long as it allows contact holes to be formed so that wiring patterns can be formed between the first electrode and the substrate, and insulation from unconnected wiring patterns is ensured. For example, the insulating layer may be made of a resin such as polyimide, silicon oxide, silicon nitride, or the like.

[0073] [electrode] A pair of electrodes can be used as the electrodes. The pair of electrodes may be an anode and a cathode. When an electric field is applied in the direction in which the organic light-emitting element emits light, the electrode with a higher potential is the anode, and the other is the cathode. It can also be said that the electrode that supplies holes to the light-emitting layer is the anode, and the electrode that supplies electrons is the cathode.

[0074] The anode may be made of a material with a high work function. For example, simple metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, mixtures containing these metals, alloys of these metals, and metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and zinc indium oxide can be used. Conductive polymers such as polyaniline, polypyrrole, and polythiophene can also be used as the anode.

[0075] These electrode materials may be used alone or in combination of two or more. The anode may be composed of one layer or multiple layers.

[0076] When the electrode is used as a reflective electrode, for example, chromium, aluminum, silver, titanium, tungsten, molybdenum, or alloys thereof, or laminates thereof can be used. The above materials can also function as a reflective film without functioning as an electrode. Furthermore, when a transparent electrode is used as the electrode, a transparent conductive oxide layer such as indium tin oxide (ITO) or indium zinc oxide can be used, but is not limited to these. Photolithography technology can be used to form the electrode.

[0077] On the other hand, a material with a low work function may be selected as the cathode material. Examples include simple metals such as alkali metals (e.g., lithium), alkaline earth metals (e.g., calcium), aluminum, titanium, manganese, silver, lead, and chromium, as well as mixtures containing these metals. Alternatively, alloys combining these simple metals may be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver may be used. Metal oxides such as indium tin oxide (ITO) may also be used. These electrode materials may be used alone or in combination. The cathode may have a single-layer or multi-layer structure. Silver may be used as the cathode, and a silver alloy may be used to reduce silver aggregation. The alloy ratio is not important as long as silver aggregation is reduced. For example, the silver:other metal ratio may be 1:1 or 3:1.

[0078] The cathode may be a top-emission element using an oxide conductive layer such as ITO, or a bottom-emission element using a reflective electrode such as aluminum (Al), and is not particularly limited. The method for forming the cathode is not particularly limited, but using a DC or AC sputtering method, for example, can provide good coverage of the formed film and reduce the resistance of the cathode.

[0079] [Pixel isolation layer] The pixel separation layer may be formed of silicon oxides such as silicon nitride (SiN), silicon oxynitride (SiON), or silicon oxide (SiO) formed using a chemical vapor deposition (CVD) method. To increase the in-plane resistance of the organic compound layer, the thickness of the organic compound layer, particularly the hole transport layer, may be thinned on the sidewalls of the pixel separation layer. Specifically, the thickness of the organic compound layer on the sidewalls can be thinned by increasing the taper angle of the sidewalls of the pixel separation layer or the thickness of the pixel separation layer, thereby increasing vignetting during deposition.

[0080] On the other hand, the sidewall taper angle and film thickness of the pixel separation layer can be adjusted to the extent that voids are not formed in the protective layer formed thereon. By preventing voids from being formed in the protective layer, the occurrence of defects in the protective layer can be reduced. Since the occurrence of defects in the protective layer is reduced, deterioration of reliability such as the occurrence of dark spots and poor conduction of the second electrode can be reduced.

[0081] According to this embodiment, charge leakage to adjacent pixels can be effectively suppressed even if the taper angle of the sidewall of the pixel separation layer is not steep. As a result of this study, it was found that charge leakage can be sufficiently reduced if the taper angle is between 60 degrees and 90 degrees. The thickness of the pixel separation layer may be between 10 nm and 150 nm. Similar effects can also be achieved even if the pixel separation layer is composed only of pixel electrodes without a pixel separation layer. However, in this case, short circuits in organic light-emitting elements can be reduced by making the thickness of the pixel electrode less than half that of the organic layer or by making the edge of the pixel electrode forward tapered at less than 60 degrees.

[0082] Furthermore, even when the first electrode is a cathode and the second electrode is an anode, a wide color gamut and low-voltage operation are possible by forming an electron transport material and a charge transport layer, and an emitting layer on the charge transport layer.

[0083] [Organic compound layer] The organic compound layer may be formed as a single layer or as multiple layers. When multiple layers are present, they may be referred to as hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc., depending on their functions. The organic compound layer is primarily composed of organic compounds but may also contain inorganic atoms or compounds. The organic compound layer may contain, for example, copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, zinc, etc. The organic compound layer may be disposed between the first electrode and the second electrode, or may be disposed in contact with the first electrode and the second electrode. When multiple light-emitting layers are present, a charge generation section may be disposed between the first and second light-emitting layers. The charge generation section may contain an organic compound having a lowest unoccupied molecular orbital energy (LUMO) of -5.0 eV or less. The same applies when a charge generation section is disposed between the second and third light-emitting layers.

[0084] [Protective layer] A protective layer may be provided on the cathode. For example, by adhering glass with a moisture absorbent on the cathode, the penetration of moisture and other contaminants into the organic compound layer can be reduced, thereby reducing the occurrence of display defects. In another embodiment, a passivation layer such as silicon nitride may be provided on the cathode to reduce the penetration of moisture and other contaminants into the organic compound layer. For example, after forming the cathode, the cathode may be transferred to another chamber without breaking the vacuum, and a 2 μm-thick silicon nitride may be formed by CVD to serve as a protective layer. After forming the protective layer by CVD, a protective layer may be formed by atomic layer deposition (ALD). The material of the protective layer formed by ALD is not limited, and may be silicon nitride, silicon oxide, aluminum oxide, or the like. Silicon nitride may be further formed by CVD on the protective layer formed by ALD. The protective layer formed by ALD may have a thickness smaller than that of the protective layer formed by CVD. Specifically, the thickness of the protective layer formed by ALD may be 50% or less, or even 10% or less, of the protective layer formed by CVD.

[0085] [Color Filter] A color filter may be provided on the protective layer. For example, a color filter taking into consideration the size of the organic light-emitting element may be provided on another substrate, and the substrate on which the color filter is formed may be bonded to the substrate on which the organic light-emitting element is provided. Alternatively, for example, a color filter may be patterned on the above-mentioned protective layer using photolithography technology. The color filter may be made of a polymer.

[0086] [Planarization layer] A planarization layer may be disposed between the color filter and the protective layer. The planarization layer is provided for the purpose of reducing the unevenness of the layers below the planarization layer. It may also be called a material resin layer without limiting the purpose. The planarization layer may be composed of an organic compound, and may be a low molecular weight or a high molecular weight. In consideration of reducing the unevenness, a high molecular weight organic compound may be used for the planarization layer.

[0087] The planarization layers may be provided above and below the color filter. In this case, the constituent materials of the planarization layers may be the same or different. Specific examples of the material for the planarization layer include polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.

[0088] [Microlens] The organic light-emitting device may have an optical component such as a microlens on its light-emitting side. The microlens may be made of acrylic resin, epoxy resin, or the like. The microlens may be intended to increase the amount of light extracted from the organic light-emitting device or to control the direction of the extracted light. The microlens may have a hemispherical shape. When the microlens has a hemispherical shape, among the tangents to the hemisphere, there is a tangent that is parallel to the insulating layer, and the point of contact between this tangent and the hemisphere is the vertex of the microlens. The vertex of the microlens can be determined in the same way in any cross-sectional view. In other words, among the tangents to the semicircle of the microlens in the cross-sectional view, there is a tangent that is parallel to the insulating layer, and the point of contact between this tangent and the semicircle is the vertex of the microlens.

[0089] It is also possible to define the midpoint of a microlens. In the cross section of the microlens, a line segment is imagined from the point where an arc shape ends to the point where another arc shape ends, and the midpoint of this line segment can be called the midpoint of the microlens. The cross section for determining the vertex and midpoint may be a cross section perpendicular to the insulating layer.

[0090] The microlens has a first surface having a convex portion and a second surface opposite the first surface. The second surface can be disposed closer to the functional layer (light-emitting layer) than the first surface. To achieve this configuration, it is necessary to form the microlens on the light-emitting device. If the functional layer is an organic layer, high-temperature processes can be avoided in the microlens manufacturing process. Furthermore, if the second surface is disposed closer to the functional layer than the first surface, the glass transition temperatures of the organic compounds constituting the organic layer may all be 100°C or higher, and are preferably, for example, 130°C or higher.

[0091] [Counter substrate] An opposing substrate may be disposed on the planarization layer. The opposing substrate is called an opposing substrate because it is provided at a position corresponding to the aforementioned substrate. The opposing substrate may be made of the same material as the aforementioned substrate. When the aforementioned substrate is defined as a first substrate, the opposing substrate may be a second substrate.

[0092] [Organic layer] The organic compound layers (hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, electron injection layer, etc.) constituting the organic light-emitting element according to an embodiment of the present disclosure may be formed by the following method.

[0093] The organic compound layer constituting the organic light-emitting device according to the embodiment of the present disclosure can be formed by dry processes such as vacuum deposition, ionization deposition, sputtering, plasma, etc. Alternatively to the dry process, a wet process can be used in which the compound is dissolved in an appropriate solvent and a layer is formed by a known coating method (e.g., spin coating, dipping, casting, LB method, inkjet method, etc.).

[0094] Here, when a layer is formed by a vacuum deposition method or a solution coating method, crystallization is unlikely to occur and the layer has excellent stability over time. When a film is formed by a coating method, the film can be formed by combining it with an appropriate binder resin.

[0095] Examples of the binder resin include, but are not limited to, polyvinylcarbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenol resin, epoxy resin, silicone resin, and urea resin.

[0096] These binder resins may be used singly or in combination as homopolymers or copolymers, and may further contain known additives such as plasticizers, antioxidants, and ultraviolet absorbers, as needed.

[0097] [Pixel circuit] The light-emitting device may have a pixel circuit connected to the light-emitting element. The pixel circuit may be an active matrix type that controls the emission of the first light-emitting element and the second light-emitting element independently. The active matrix type circuit may be voltage-programmed or current-programmed. The drive circuit has a pixel circuit for each pixel. The pixel circuit may have a light-emitting element, a transistor that controls the emission brightness of the light-emitting element, a transistor that controls the emission timing, a capacitor that holds the gate voltage of the transistor that controls the emission brightness, and a transistor for connecting to GND without going through the light-emitting element.

[0098] The light-emitting device has a display region and a peripheral region arranged around the display region. The display region has pixel circuits, and the peripheral region has a display control circuit. The mobility of a transistor constituting the pixel circuit may be lower than the mobility of a transistor constituting the display control circuit.

[0099] The slope of the current-voltage characteristics of the transistors that make up the pixel circuit may be smaller than the slope of the current-voltage characteristics of the transistors that make up the display control circuit. The slope of the current-voltage characteristics can be measured using the so-called Vg-Ig characteristics.

[0100] The transistors that make up the pixel circuit are transistors connected to the light-emitting elements, such as the first light-emitting element.

[0101] [Pixels] An organic light emitting device includes a plurality of pixels, each of which includes sub-pixels that emit different colors, for example, RGB colors.

[0102] A pixel has an area called a pixel aperture that emits light. The pixel aperture may be 15 μm or less, or 5 μm or more. More specifically, it may be 11 μm, 9.5 μm, 7.4 μm, 6.4 μm, etc.

[0103] The spacing between the subpixels may be 10 μm or less, and specifically may be 8 μm, 7.4 μm, or 6.4 μm.

[0104] The pixels may be arranged in a known manner in a plan view. For example, they may be in a stripe arrangement, a delta arrangement, a pentile arrangement, or a Bayer arrangement. The shape of the subpixels in a plan view may be any known shape. For example, they may be rectangular, quadrilaterals such as diamonds, or hexagons. Of course, a shape that is close to a rectangle, rather than an exact shape, is included in the rectangle. The shape of the subpixels and the pixel arrangement may be used in combination.

[0105] [Uses of the organic light-emitting device according to the embodiment of the present disclosure] The organic light-emitting device according to the embodiment of the present disclosure can be used as a component of a display device or a lighting device, and can also be used as an exposure light source for an electrophotographic image forming device, a backlight for a liquid crystal display device, or a light-emitting device having a white light source and a color filter.

[0106] The display device may be an image information processing device that has an image input unit that inputs image information from an area CCD, linear CCD, memory card, etc., has an information processing unit that processes the input information, and displays the input image on the display unit.

[0107] The display unit of the imaging device or inkjet printer may have a touch panel function. The driving method of this touch panel function may be an infrared method, a capacitance method, a resistive film method, or an electromagnetic induction method, and is not particularly limited. The display device may also be used in the display unit of a multifunction printer.

[0108] Next, further explanation will be given with reference to the drawings. Fig. 17(a) shows an example of a pixel PIX arranged in the light-emitting device 10 of the above embodiment. The pixel has sub-pixels 810 (pixels PIX). The sub-pixels are divided into 810R, 810G, and 810B based on their light emission. The emitted colors may be distinguished by the wavelength of light emitted from the light-emitting layer, or the light emitted from the sub-pixels may be selectively transmitted or color-converted using a color filter or the like. Each sub-pixel has a reflective electrode 802 as a first electrode on an interlayer insulating layer 801, an insulating layer 803 covering the edge of the reflective electrode 802, an organic compound layer 804 covering the first electrode and the insulating layer, a transparent electrode 805 as a second electrode, a protective layer 806, and a color filter 807.

[0109] A transistor and a capacitor may be disposed below or inside the interlayer insulating layer 801. The transistor and the first electrode may be electrically connected via a contact hole (not shown) or the like.

[0110] The insulating layer 803 may also be called a bank or a pixel separation film. The insulating layer 803 covers the edges of the first electrodes and is disposed to surround the first electrodes. The portions of the first electrodes not covered by the insulating layer 803 come into contact with the organic compound layer 804 and become light-emitting regions.

[0111] The organic compound layer 804 includes a hole injection layer 841 , a hole transport layer 842 , a first light-emitting layer 843 , a second light-emitting layer 844 , and an electron transport layer 845 .

[0112] The second electrode may be a transparent electrode, a reflective electrode, or a semi-transparent electrode.

[0113] The protective layer 806 reduces the penetration of moisture into the organic compound layer. Although the protective layer is illustrated as a single layer, it may be a multi-layer structure. Each layer may be an inorganic compound layer and an organic compound layer.

[0114] The color filters 807 are divided into 807R, 807G, and 807B depending on their colors. The color filters may be formed on a planarization film (not shown). A resin protective layer (not shown) may be disposed on the color filters. The color filters may be formed on a protective layer 806. The color filters may be provided on an opposing substrate such as a glass substrate and then bonded thereto.

[0115] A display device 800 in FIG. 17(b) (corresponding to the light-emitting device 10 of the above embodiment) includes an organic light-emitting element 826 and a TFT 818 as an example of a transistor. A substrate 811 made of glass, silicon, or the like is provided with an insulating layer 812 thereon. An active element such as the TFT 818 is disposed on the insulating layer, and a gate electrode 813, a gate insulating film 814, and a semiconductor layer 815 of the active element are disposed on the insulating layer. The TFT 818 also includes the semiconductor layer 815, a drain electrode 816, and a source electrode 817. An insulating film 819 is provided on the top of the TFT 818. An anode 821 constituting the organic light-emitting element 826 and the source electrode 817 are connected via a contact hole 820 provided in the insulating film.

[0116] The electrical connection between the electrodes (anode, cathode) included in the organic light-emitting element 826 and the electrodes (source electrode, drain electrode) included in the TFT is not limited to the embodiment shown in Figure 17(b). In other words, it is sufficient that either the anode or the cathode is electrically connected to either the TFT source electrode or the drain electrode. TFT stands for thin film transistor.

[0117] 17(b), the organic compound layer is illustrated as a single layer, but the organic compound layer 822 may be a multi-layer structure. A first protective layer 824 and a second protective layer 825 are provided on the cathode 823 to reduce deterioration of the organic light-emitting element.

[0118] In the display device 800 of FIG. 17(b), transistors are used as switching elements, but other switching elements may be used instead.

[0119] Furthermore, the transistors used in the display device 800 of Fig. 17(b) are not limited to transistors using single-crystal silicon wafers, but may also be thin-film transistors having an active layer on the insulating surface of a substrate. Examples of active layers include non-single-crystal silicon such as single-crystal silicon, amorphous silicon, and microcrystalline silicon, and non-single-crystal oxide semiconductors such as indium zinc oxide and indium gallium zinc oxide. Thin-film transistors are also called TFT elements.

[0120] The transistors included in the display device 800 of Figure 17(b) may be formed within a substrate such as a silicon substrate. Here, "formed within a substrate" means that the substrate itself, such as a silicon substrate, is processed to form the transistors. In other words, having a transistor within a substrate can be seen as the substrate and the transistor being formed integrally.

[0121] The organic light-emitting element according to this embodiment has its light emission brightness controlled by a TFT, which is an example of a switching element. By providing multiple organic light-emitting elements on a surface, an image can be displayed based on the respective light emission brightnesses. Here, the switching element according to this embodiment is not limited to a TFT, but may also be a transistor formed from low-temperature polysilicon or an active matrix driver formed on a substrate such as a silicon substrate. "On the substrate" can also be referred to as "inside the substrate." Whether to provide a transistor in the substrate or to use a TFT is determined by the size of the display unit. For example, if the size is about 0.5 inches, the organic light-emitting element may be provided on a silicon substrate.

[0122] FIG. 18 is a schematic diagram illustrating an example of a display device using the light-emitting device 10 of the above embodiment. The display device 1000 may include a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. The touch panel 1003 and the display panel 1005 are connected to flexible printed circuits FPCs 1002 and 1004. Active elements such as transistors are disposed on the circuit board 1007. The battery 1008 may not be disposed if the display device 1000 is not a portable device, and even if it is a portable device, it does not need to be disposed in this position. The light-emitting device 10 of the above embodiment can be applied to the display panel 1005. The pixels PIX disposed in the light-emitting device 10 functioning as the display panel 1005 are connected to active elements such as transistors disposed on the circuit board 1007 and operate.

[0123] The display device 1000 shown in FIG. 18 may be used as a display unit of a photoelectric conversion device (which may also be called an imaging device) that has an optical unit with multiple lenses and an imaging element that receives light that has passed through the optical unit and photoelectrically converts it into an electrical signal. The photoelectric conversion device may have a display unit that displays information acquired by the imaging element. The display unit may be a display unit exposed to the outside of the photoelectric conversion device or a display unit located within a viewfinder. The photoelectric conversion device may be a digital camera or a digital video camera.

[0124] FIG. 19 is a schematic diagram illustrating an example of a photoelectric conversion device using the light-emitting device 10 of the above embodiment. The photoelectric conversion device 1100 may include a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The photoelectric conversion device 1100 may also be called an imaging device. The light-emitting device 10 of the above embodiment may be applied to the viewfinder 1101 or the rear display 1102, which are display units. In this case, the light-emitting device 10 may display not only an image to be captured, but also environmental information, imaging instructions, and the like. The environmental information may include the intensity of external light, the direction of external light, the moving speed of the subject, the possibility that the subject will be blocked by an obstruction, and the like.

[0125] Since the timing suitable for capturing an image is often very short, it is better to display information as soon as possible. Therefore, a light-emitting device 10 having pixels PIX including light-emitting elements using an organic light-emitting material such as an organic EL element may be used in a viewfinder 1101 or a rear display 1102. This is because organic light-emitting materials have a fast response speed. A light-emitting device 10 using an organic light-emitting material is more suitable than a liquid crystal display device for these devices, which require a high display speed.

[0126] The photoelectric conversion device 1100 has an optical section (not shown). The optical section has multiple lenses, which form an image on a photoelectric conversion element (not shown) housed in a housing 1104 that receives light that has passed through the optical section. The focus of the multiple lenses can be adjusted by adjusting their relative positions. This operation can also be performed automatically.

[0127] The light emitting device 10 may be applied to a display unit of an electronic device. In this case, the light emitting device 10 may have both a display function and an operation function. Examples of the portable terminal include a mobile phone such as a smartphone, a tablet, and a head-mounted display.

[0128] FIG. 20 is a schematic diagram showing an example of an electronic device using the light-emitting device 10 of the above embodiment. The electronic device 1200 has a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may have a circuit, a printed circuit board having the circuit, a battery, and a communication unit. The operation unit 1202 may be a button or a touch panel type reaction unit. The operation unit 1202 may be a biometric recognition unit that recognizes a fingerprint to perform unlocking or the like. A portable device having a communication unit can also be called a communication device. The light-emitting device 10 of the above embodiment can be applied to the display unit 1201.

[0129] 21(a) and 21(b) are schematic diagrams illustrating an example of a display device using the light-emitting device 10 of the above embodiment. FIG. 21(a) illustrates a display device such as a television monitor or a PC monitor. The display device 1300 has a frame 1301 and a display unit 1302. The light-emitting device 10 of the above embodiment can be applied to the display unit 1302. The display device 1300 may have a base 1303 that supports the frame 1301 and the display unit 1302. The base 1303 is not limited to the form shown in FIG. 21(a). For example, the bottom edge of the frame 1301 may also serve as the base 1303. The frame 1301 and the display unit 1302 may be curved. The radius of curvature may be 5000 mm or more and 6000 mm or less.

[0130] FIG. 21(b) is a schematic diagram illustrating another example of a display device using the light-emitting device 10 of the above embodiment. The display device 1310 of FIG. 21(b) is configured to be bendable, and is a so-called foldable display device. The display device 1310 has a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The light-emitting device 10 of the above embodiment can be applied to the first display unit 1311 and the second display unit 1312. The first display unit 1311 and the second display unit 1312 may be a single display unit without any joints. The first display unit 1311 and the second display unit 1312 can be separated by the bending point. The first display unit 1311 and the second display unit 1312 may display different images, or the first display unit and the second display unit 1312 may display a single image.

[0131] FIG. 22 is a schematic diagram illustrating an example of a lighting device using the light-emitting device 10 of the above embodiment. The lighting device 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion unit 1405. The light-emitting device 10 of the above embodiment can be applied to the light source 1402. The optical film 1404 may be a filter that improves the color rendering of the light source. The light diffusion unit 1405 can effectively diffuse light from the light source, such as for lighting, and deliver the light over a wide area. If necessary, a cover may be provided on the outermost part. The lighting device 1400 may include both the optical film 1404 and the light diffusion unit 1405, or only one of them.

[0132] The lighting device 1400 is, for example, a device that illuminates a room. The lighting device 1400 may emit white, daylight white, or any other color from blue to red. It may have a dimming circuit that adjusts the light intensity. The lighting device 1400 may have a power supply circuit connected to the light emitting device 10 that functions as the light source 1402. The power supply circuit is a circuit that converts AC voltage into DC voltage. White has a color temperature of 4200K, and daylight white has a color temperature of 5000K. The lighting device 1400 may also have a color filter. The lighting device 1400 may also have a heat sink. The heat sink dissipates heat from within the device to the outside, and examples of the heat sink include metal with a high specific heat, liquid silicon, etc.

[0133] FIG. 23 is a schematic diagram of an automobile having a tail lamp, which is an example of a vehicle lamp using the light emitting device 10 of the above embodiment. The automobile 1500 may have a tail lamp 1501, and may be configured to turn on the tail lamp 1501 when braking or the like is performed. The light emitting device 10 of the above embodiment may be used as a headlamp as a vehicle lamp. An automobile is an example of a mobile body, and the mobile body may be a ship, a drone, an aircraft, a railroad vehicle, an industrial robot, or the like. The mobile body may have a body and a lamp provided thereon. The lamp may indicate the current location of the body.

[0134] The light emitting device 10 of the above embodiment can be applied to a tail lamp 1501. The tail lamp 1501 may have a protective member that protects the light emitting device 10 functioning as the tail lamp 1501. The protective member may be made of any material as long as it has a certain degree of strength and is transparent, but may be made of polycarbonate or the like. The protective member may also be made by mixing a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like with polycarbonate.

[0135] The automobile 1500 may have a body 1503 and a window 1502 attached thereto. The window may be a window for checking the front and rear of the automobile, or may be a transparent display such as a head-up display. The light-emitting device 10 of the above embodiment may be used in the transparent display. In this case, the constituent materials of the electrodes and the like of the light-emitting device 10 are made of transparent materials.

[0136] 24(a) and 24(b), a further application example of the light emitting device 10 of the above embodiment will be described. The light emitting device 10 can be applied to systems that can be worn as a wearable device, such as smart glasses, a head-mounted display (HMD), or smart contact lenses. An image capturing and displaying device used in such an application example has an image capturing device capable of photoelectrically converting visible light and a light emitting device capable of emitting visible light.

[0137] 24(a) illustrates glasses 1600 (smart glasses) according to one application example. An imaging device 1602 such as a CMOS sensor or a SPAD is provided on the front side of a lens 1601 of the glasses 1600. In addition, the light emitting device 10 according to the above embodiment is provided on the back side of the lens 1601.

[0138] The glasses 1600 further include a control device 1603. The control device 1603 functions as a power source that supplies power to the image capture device 1602 and the light emitting device 10 according to each embodiment. The control device 1603 also controls the operations of the image capture device 1602 and the light emitting device 10. The lens 1601 is formed with an optical system for focusing light onto the image capture device 1602.

[0139] FIG. 24(b) illustrates glasses 1610 (smart glasses) according to one application example. The glasses 1610 include a control device 1612, which is equipped with an imaging device corresponding to the imaging device 1602 and a light-emitting device 10. A lens 1611 includes an optical system for projecting light emitted from the imaging device in the control device 1612 and the light-emitting device 10, and an image is projected onto the lens 1611. The control device 1612 functions as a power source for supplying power to the imaging device and the light-emitting device 10 and controls the operation of the imaging device and the light-emitting device 10. The control device 1612 may also include a gaze detection unit that detects the gaze of the wearer. Infrared light may be used for gaze detection. The infrared light-emitting unit emits infrared light toward the eyeball of a user gazing at a displayed image. An imaging unit having a light-receiving element detects the emitted infrared light reflected from the eyeball, thereby obtaining an image of the eyeball. By providing a reduction means for reducing the amount of light from the infrared light emitting section to the display section in a plan view, degradation of image quality is reduced.

[0140] The gaze of the user relative to the displayed image is detected from an image of the eyeball obtained by capturing infrared light. Any known method can be used for gaze detection using the image of the eyeball. As an example, a gaze detection method based on the Purkinje image formed by reflection of irradiated light on the cornea can be used.

[0141] More specifically, gaze detection processing is performed based on the pupil-corneal reflex method, which calculates a gaze vector representing the direction (rotation angle) of the eyeball based on the pupil image and Purkinje image included in the captured image of the eyeball, thereby detecting the user's gaze.

[0142] The light emitting device 10 according to the embodiment of the present disclosure may have an imaging device having a light receiving element, and may control the display image based on information on the user's line of sight from the imaging device.

[0143] Specifically, the light emitting device 10 determines a first field of view area where the user gazes and a second field of view area other than the first field of view area based on the line-of-sight information. The first field of view area and the second field of view area may be determined by a control device of the light emitting device 10, or may be determined by an external control device and received. In the display area of ​​the light emitting device 10, the display resolution of the first field of view area may be controlled to be higher than the display resolution of the second field of view area. In other words, the resolution of the second field of view area may be lower than that of the first field of view area.

[0144] The display area includes a first display area and a second display area different from the first display area, and a high-priority area is determined from the first display area and the second display area based on line-of-sight information. The first display area and the second display area may be determined by a control device of the light-emitting device 10, or may be determined by an external control device and received. The resolution of the high-priority area may be controlled to be higher than the resolution of areas other than the high-priority area. In other words, the resolution of an area with a relatively low priority may be lowered.

[0145] Note that AI may be used to determine the first field of view area and areas with high priority. The AI ​​may be a model configured to estimate the angle of gaze and the distance to an object in the line of sight from the image of the eyeball, using as training data an image of the eyeball and the actual direction in which the eyeball in the image was looking. The AI ​​program may be included in the light-emitting device 10, the imaging device, or an external device. If included in an external device, it is transmitted to the light-emitting device 10 via communication.

[0146] When display control is performed based on visual recognition detection, the smart glasses can be applied to smart glasses that further include an imaging device for capturing images of the outside world. The smart glasses can display captured outside information in real time.

[0147] <Summary of the embodiment> The disclosure of the present specification includes at least the following light emitting device and method of manufacturing an article. (Item 1) A plurality of light-emitting elements; a plurality of conversion circuits provided corresponding to the plurality of light-emitting elements, respectively; a voltage generating unit that generates a plurality of reference voltages; each of the plurality of conversion circuits converts an externally supplied digital signal into an analog signal for driving a corresponding one of the plurality of light-emitting elements, using the plurality of reference voltages generated by the voltage generation unit; The light emitting device, wherein at least one of the plurality of reference voltages is supplied from the voltage generating unit to each of the plurality of conversion circuits via a buffer circuit. (Item 2) 2. The light emitting device according to item 1, wherein the plurality of conversion circuits include two or more conversion circuits to which the at least one reference voltage is supplied via a common buffer circuit. (Item 3) the plurality of reference voltages generated by the voltage generating unit include a first reference voltage and a second reference voltage; 3. The light emitting device according to item 1 or 2, characterized in that a common buffer circuit is provided for each first number of conversion circuits for the first reference voltage, and a common buffer circuit is provided for each second number of conversion circuits different from the first number for the second reference voltage. (Item 4) 4. The light emitting device according to any one of items 1 to 3, wherein the plurality of conversion circuits include two or more conversion circuits to which the at least one reference voltage is supplied via mutually different buffer circuits. (Item 5) the plurality of conversion circuits include a first group of conversion circuits to which the at least one reference voltage is supplied via a first buffer circuit, and a second group of conversion circuits to which the at least one reference voltage is supplied via a second buffer circuit; 5. The light emitting device according to any one of items 1 to 4, wherein the first buffer circuit and the second buffer circuit are connected in series, and the output of the first buffer circuit is input to the second buffer circuit. (Item 6) 6. The light emitting device according to item 5, wherein the first buffer circuit is composed of a source follower consisting of a MOS transistor and a current source, and the second buffer circuit is composed of a unity gain buffer consisting of a differential amplifier circuit. (Item 7) 7. The light emitting device according to item 5 or 6, wherein the power of the first buffer circuit is greater than the power of the second buffer circuit. (Item 8) 8. The light emitting device according to any one of items 5 to 7, wherein the area of ​​the first buffer circuit is larger than the area of ​​the second buffer circuit. (Item 9) 9. The light emitting device according to any one of items 5 to 8, wherein the noise of the first buffer circuit is smaller than the noise of the second buffer circuit. (Item 10) the first group of conversion circuits is further supplied with the at least one reference voltage via a third buffer circuit; the second group of conversion circuits is further supplied with the at least one reference voltage via a fourth buffer circuit; 10. The light emitting device according to any one of items 5 to 9, wherein the third buffer circuit and the fourth buffer circuit are connected in parallel. (Item 11) the plurality of conversion circuits include a first group of conversion circuits to which the at least one reference voltage is supplied via a third buffer circuit, and a second group of conversion circuits to which the at least one reference voltage is supplied via a fourth buffer circuit; 5. The light emitting device according to any one of items 1 to 4, wherein the third buffer circuit and the fourth buffer circuit are connected in parallel. (Item 12) the voltage generating unit generates the plurality of reference voltages using a resistor string connected between two terminals; 12. The light emitting device according to any one of items 1 to 11, wherein a voltage is applied to each of the two terminals via a buffer circuit. (Item 13) the plurality of reference voltages generated by the voltage generating unit include a first reference voltage and a second reference voltage; the light emitting device further includes a second resistor string connected between the output terminal of the first reference voltage and the output terminal of the second reference voltage in the voltage generating unit; the first reference voltage and the second reference voltage are input to the second resistor string via buffer circuits, 13. The light emitting device according to any one of items 1 to 12, wherein each of the plurality of conversion circuits is supplied with a plurality of voltages generated by the second resistor string. (Item 14) the plurality of conversion circuits include a first group of conversion circuits and a second group of conversion circuits; Item 14. The light emitting device according to item 13, wherein the second resistor string is provided for each of the first group of conversion circuits and the second group of conversion circuits. (Item 15) the plurality of conversion circuits include a first group of conversion circuits and a second group of conversion circuits; 15. The light emitting device according to any one of items 1 to 14, wherein the voltage generating unit is provided for each of the first group of conversion circuits and the second group of conversion circuits. (Item 16) 16. A light emitting device according to any one of items 1 to 15, characterized in that each of the plurality of conversion circuits has a holding circuit that temporarily holds the at least one reference voltage supplied from the voltage generating unit, and after the at least one reference voltage is held in the holding circuit, the light emitting device converts the digital signal into the analog signal using the at least one reference voltage held in the holding circuit. (Item 17) 17. The light emitting device according to item 16, wherein the operation of the buffer circuit is stopped during a period in which the holding circuit is made to hold the at least one reference voltage. (Item 18) 18. A light emitting device according to any one of items 1 to 17, characterized in that the same power supply is used for a plurality of buffer circuits provided for one of the plurality of reference voltages, and different power supplies are used for the buffer circuit provided for one of the plurality of reference voltages and the buffer circuits provided for the other reference voltages. (Item 19) 19. The light emitting device according to any one of items 1 to 18, further comprising a transfer circuit that transfers the digital signal to each of the plurality of conversion circuits. (Item 20) 20. The light emitting device according to any one of items 1 to 19, further comprising a drive circuit that drives each of the plurality of light emitting elements using the analog signals output from each of the plurality of conversion circuits. (Item 21) 21. The light emitting device according to any one of items 1 to 20, wherein the buffer circuit has an input / output through function and can be switched between use and non-use depending on the operation mode. (Item 22) a first detector that detects the light emission luminance of each of the plurality of light emitting elements; and a controller that controls the buffer circuit; the buffer circuit has an output offset adjustment mechanism; The light emitting device described in any one of items 1 to 21, characterized in that the control unit controls the output of the buffer circuit using the output offset adjustment mechanism so that the light emitting brightness of each of the plurality of light emitting elements is corrected based on the detection result of the first detection unit. (Item 23) the plurality of buffer circuits are provided for the plurality of reference voltages, respectively; a second detection unit that detects an output offset value between the plurality of buffer circuits; and a control unit that controls the plurality of buffer circuits, each of the plurality of buffer circuits has an output offset adjustment mechanism; The light emitting device described in any one of items 1 to 22, characterized in that the control unit controls the output of the buffer circuit using the output offset adjustment mechanism so that the output offset value between the multiple buffer circuits is corrected based on the detection result of the second detection unit. (Item 24) 1. A wearable device having a display device for displaying an image, A wearable device characterized in that the display device has the light-emitting device described in any one of items 1 to 23. (Item 25) 24. A display device comprising: the light-emitting device according to any one of items 1 to 23; and an active element connected to the light-emitting device. (Item 26) an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image; 24. A photoelectric conversion device, wherein the display unit displays an image captured by the imaging element, and the photoelectric conversion device comprises the light-emitting device according to any one of items 1 to 23. (Item 27) A display unit is provided in the housing, and a communication unit is provided in the housing and communicates with an external device. 24. An electronic device, wherein the display unit comprises the light-emitting device according to any one of items 1 to 23. (Item 28) A lighting device having a light source and at least one of a light diffusion unit and an optical film, 24. A lighting device, wherein the light source comprises the light emitting device according to any one of items 1 to 23. (Item 29) A moving body having a body and a lighting fixture provided on the body, A moving body, characterized in that the lighting fixture has the light-emitting device described in any one of items 1 to 23.

[0148] The invention is not limited to the above-described embodiments, and various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0149] 10: Light emitting device, 100: pixel array, 101: pixel (light emitting element), 200: vertical scanning circuit, 300: signal output circuit, 301: horizontal scanning circuit, 302: column DAC circuit, 303: column driver circuit, 350 to 354: buffer circuits, 400: control circuit, 500: voltage generation circuit

Claims

1. A plurality of light-emitting elements; a plurality of conversion circuits provided corresponding to the plurality of light-emitting elements, respectively; a voltage generating unit that generates a plurality of reference voltages; each of the plurality of conversion circuits converts an externally supplied digital signal into an analog signal for driving a corresponding one of the plurality of light-emitting elements, using the plurality of reference voltages generated by the voltage generation unit; At least one of the plurality of reference voltages is supplied from the voltage generating unit to each of the plurality of conversion circuits via a buffer circuit.

2. 2. The light emitting device according to claim 1, wherein the plurality of conversion circuits include two or more conversion circuits to which the at least one reference voltage is supplied via a common buffer circuit.

3. the plurality of reference voltages generated by the voltage generating unit include a first reference voltage and a second reference voltage; 2. The light-emitting device according to claim 1, wherein a common buffer circuit is provided for each first number of conversion circuits for the first reference voltage, and a common buffer circuit is provided for each second number of conversion circuits different from the first number for the second reference voltage.

4. 2. The light emitting device according to claim 1, wherein the plurality of conversion circuits include two or more conversion circuits to which the at least one reference voltage is supplied via different buffer circuits.

5. the plurality of conversion circuits include a first group of conversion circuits to which the at least one reference voltage is supplied via a first buffer circuit, and a second group of conversion circuits to which the at least one reference voltage is supplied via a second buffer circuit; 2. The light emitting device according to claim 1, wherein the first buffer circuit and the second buffer circuit are connected in series, and an output of the first buffer circuit is input to the second buffer circuit.

6. 6. The light emitting device according to claim 5, wherein the first buffer circuit is configured as a source follower made up of a MOS transistor and a current source, and the second buffer circuit is configured as a unity gain buffer made up of a differential amplifier circuit.

7. 6. The light emitting device according to claim 5, wherein the power of the first buffer circuit is greater than the power of the second buffer circuit.

8. 6. The light emitting device according to claim 5, wherein the area of ​​the first buffer circuit is larger than the area of ​​the second buffer circuit.

9. 6. The light emitting device according to claim 5, wherein the noise of the first buffer circuit is smaller than the noise of the second buffer circuit.

10. the first group of conversion circuits is further supplied with the at least one reference voltage via a third buffer circuit; the second group of conversion circuits is further supplied with the at least one reference voltage via a fourth buffer circuit; 6. The light emitting device according to claim 5, wherein the third buffer circuit and the fourth buffer circuit are connected in parallel.

11. the plurality of conversion circuits include a first group of conversion circuits to which the at least one reference voltage is supplied via a third buffer circuit, and a second group of conversion circuits to which the at least one reference voltage is supplied via a fourth buffer circuit; 2. The light emitting device according to claim 1, wherein the third buffer circuit and the fourth buffer circuit are connected in parallel.

12. the voltage generating unit generates the plurality of reference voltages using a resistor string connected between two terminals; 2. The light emitting device according to claim 1, wherein a voltage is applied to each of the two terminals via a buffer circuit.

13. the plurality of reference voltages generated by the voltage generating unit include a first reference voltage and a second reference voltage; the light emitting device further includes a second resistor string connected between the output terminal of the first reference voltage and the output terminal of the second reference voltage in the voltage generating unit; the first reference voltage and the second reference voltage are input to the second resistor string via buffer circuits, 2. The light emitting device according to claim 1, wherein each of the plurality of conversion circuits is supplied with a plurality of voltages generated by the second resistor string.

14. the plurality of conversion circuits include a first group of conversion circuits and a second group of conversion circuits; 14. The light emitting device according to claim 13, wherein the second resistor string is provided for each of the first group of conversion circuits and the second group of conversion circuits.

15. the plurality of conversion circuits include a first group of conversion circuits and a second group of conversion circuits; 2. The light emitting device according to claim 1, wherein the voltage generating unit is provided for each of the first group of conversion circuits and the second group of conversion circuits.

16. 2. The light-emitting device according to claim 1, wherein each of the plurality of conversion circuits has a holding circuit that temporarily holds the at least one reference voltage supplied from the voltage generating unit, and after the at least one reference voltage is held in the holding circuit, the light-emitting device converts the digital signal into the analog signal using the at least one reference voltage held in the holding circuit.

17. 17. The light emitting device according to claim 16, wherein the buffer circuit is stopped from operating during a period in which the holding circuit is made to hold the at least one reference voltage.

18. 2. The light emitting device according to claim 1, wherein the same power supply is used for a plurality of buffer circuits provided for one of the plurality of reference voltages, and different power supplies are used for the buffer circuit provided for one of the plurality of reference voltages and the buffer circuits provided for the other reference voltages.

19. The light emitting device according to claim 1 , further comprising a transfer circuit that transfers the digital signal to each of the plurality of conversion circuits.

20. 2. The light emitting device according to claim 1, further comprising a drive circuit that drives each of the plurality of light emitting elements with the analog signals output from each of the plurality of conversion circuits.

21. 2. The light emitting device according to claim 1, wherein the buffer circuit has an input / output through function and is switchable between use and non-use depending on an operation mode.

22. a first detector that detects the light emission luminance of each of the plurality of light emitting elements; and a controller that controls the buffer circuit; the buffer circuit has an output offset adjustment mechanism; 2. The light-emitting device according to claim 1, wherein the control unit controls the output of the buffer circuit using the output offset adjustment mechanism so that the light-emitting brightness of each of the plurality of light-emitting elements is corrected based on the detection result of the first detection unit.

23. the power supply further includes a plurality of buffer circuits respectively provided for the plurality of reference voltages, a second detection unit that detects an output offset value between the plurality of buffer circuits, and a control unit that controls the plurality of buffer circuits, each of the plurality of buffer circuits has an output offset adjustment mechanism; 2. The light emitting device according to claim 1, wherein the control unit controls the output of the buffer circuit using the output offset adjustment mechanism so that an output offset value between the plurality of buffer circuits is corrected based on the detection result of the second detection unit.

24. 1. A wearable device having a display device for displaying an image, 24. A wearable device, wherein the display device comprises the light-emitting device according to claim 1.

25. A display device comprising: a light-emitting device according to any one of claims 1 to 23; and an active element connected to the light-emitting device.

26. an optical unit having a plurality of lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image; 24. A photoelectric conversion device, wherein the display section displays an image captured by the imaging element, and the photoelectric conversion device comprises the light-emitting device according to claim 1.

27. A display unit is provided in the housing, and a communication unit is provided in the housing and communicates with an external device.

24. An electronic device, wherein the display unit comprises the light-emitting device according to claim 1.

28. A lighting device having a light source and at least one of a light diffusion unit and an optical film, 24. An illumination device, wherein the light source comprises a light emitting device according to claim 1.

29. A moving body having a body and a lighting fixture provided on the body, 24. A moving body, wherein the lighting fixture comprises the light emitting device according to claim 1.

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