Light-emitting devices, display devices, photoelectric converters, electronic devices, lighting devices, mobile devices and wearable devices

Abstract

To provide a technique advantageous in reducing power consumption while maintaining image quality.SOLUTION: A light-emitting device includes: a light-emitting element; a driving transistor having a first main terminal connected to the light-emitting element; a light emission control transistor arranged between a second main terminal of the driving transistor and a supply line that supplies a first potential; a write transistor that supplies a luminance signal to a control terminal of the driving transistor; and a capacitive element arranged between the second main terminal and the control terminal. A second potential is supplied to a back gate terminal of the driving transistor. One frame period includes: a write period during which the write transistor is conducted and the luminance signal is written in the control terminal; and a light emission period during which, after the write period, the light emission control transistor changes to a conductive state and the light-emitting element emits light corresponding to the luminance signal. The light emission control transistor is conducted after the start of the write period and before the end of the write period.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] There has been an increasing interest in light-emitting devices using self-emitting elements such as organic electroluminescence (EL) elements. Patent Document 1 shows a pixel including a driving transistor that supplies a current for causing an organic EL element to emit light at a predetermined luminance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, in order to suppress a decrease in image quality caused by variations in the characteristics of a driving transistor, before writing a signal voltage to the gate of the driving transistor via a signal line, a reference potential for correcting the threshold value is written via the signal line. In the operation shown in Patent Document 1, since a signal voltage and a reference potential are supplied to the signal line in one horizontal period for displaying one image, a large amount of power for charging and discharging the signal line is required.

[0005] An object of the present invention is to provide a technology advantageous for reducing power consumption while maintaining image quality.

Means for Solving the Problems

[0006] In view of the above problems, an embodiment of the present invention provides a light-emitting device in which a pixel is provided, the pixel comprising: a light-emitting element; a drive transistor whose first main terminal is connected to the light-emitting element and which supplies a current corresponding to a brightness signal to the light-emitting element; a light-emitting control transistor disposed between the second main terminal of the drive transistor and a supply line that supplies a first potential and which controls the light emission or non-emission of the light-emitting element; a write transistor for supplying the brightness signal to the control terminal of the drive transistor; and a capacitive element disposed between the second main terminal and the control terminal, wherein a second potential is supplied to the back gate terminal of the drive transistor, and one frame period includes a write period in which the write transistor conducts and the brightness signal is written to the control terminal, and a light-emitting period in which, after the write period, the light-emitting control transistor changes from a non-conductive state to a conductive state and the light-emitting element emits light corresponding to the brightness signal, and after the start of the write period and before the end of the write period, With the brightness signal input to the control terminal of the drive transistor, The light emission control transistor conducts Changes from a conductive state to a non-conductive state. It is characterized by doing so. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a technology that is advantageous for reducing power consumption while maintaining image quality. [Brief explanation of the drawing]

[0008] [Figure 1] A diagram showing an example configuration of the light-emitting device according to this embodiment. [Figure 2] Figure 1 shows an example of the pixel configuration of the light-emitting device. [Figure 3] A timing diagram showing an example of the operation of the light-emitting device in Figure 1. [Figure 4] Figure 3 illustrates the operation of the light-emitting device at each timing. [Figure 5] This figure shows a modified version of the pixels in Figure 2. [Figure 6] This figure shows a modified version of the pixels in Figure 2. [Figure 7] This figure shows a modified version of the pixels in Figure 2. [Figure 8]A timing diagram showing an example of the operation of the light-emitting device in Figure 1. [Figure 9] Figure 2 shows the parasitic capacitance of the pixel driver transistor and writing transistor, as well as the gate-source voltage of the driver transistor. [Figure 10] A diagram showing an example of a display device using the light-emitting device of this embodiment. [Figure 11] A diagram showing an example of a photoelectric conversion device using the light-emitting device of this embodiment. [Figure 12] A diagram showing an example of an electronic device using the light-emitting device of this embodiment. [Figure 13] A diagram showing an example of a display device using the light-emitting device of this embodiment. [Figure 14] A diagram showing an example of a lighting device using the light-emitting device of this embodiment. [Figure 15] A diagram showing an example of a mobile body using the light-emitting device of this embodiment. [Figure 16] A diagram showing an example of a wearable device using the light-emitting device of this embodiment. [Modes for carrying out the invention]

[0009] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0010] An embodiment of the light-emitting device according to the present disclosure will be described with reference to Figures 1 to 16(a) and 16(b). Figure 1 is a schematic diagram showing an example configuration of the light-emitting device 100 in this embodiment. The light-emitting device 100 includes a pixel array 110 and peripheral circuits arranged around the pixel array 110 to operate the pixel array 110. The pixel array 110 has a plurality of pixels 101 arranged to form a plurality of rows and a plurality of columns.

[0011] The peripheral circuit for operating (driving) each pixel of the pixel array 110 includes, for example, a scanning drive system including a write scanning circuit 201 and a light emission drive scanning circuit 202, and a signal supply system including a signal output circuit 300. In the configuration shown in FIG. 1, the write scanning circuit 201 is arranged on the left side of the pixel array 110, and the light emission drive scanning circuit 202 is arranged on the right side, but the layout is not limited to this configuration. For example, the arrangement relationship between the write scanning circuit 201 and the light emission drive scanning circuit 202 may be reversed, or the write scanning circuit 201 and the light emission drive scanning circuit 202 may be arranged on one side of the pixel array 110. Also, a pair of the write scanning circuit 201 and the light emission drive scanning circuit 202 may be arranged on each of the left and right sides, respectively.

[0012] Here, one "pixel" of the image displayed by the light emitting device 100 may be composed of a plurality of sub-pixels. In this case, the sub-pixels correspond to the pixel 101 shown in FIG. 1. More specifically, one pixel may be composed of, for example, three sub-pixels: a sub-pixel that emits red light, a sub-pixel that emits green light, and a sub-pixel that emits blue light. However, one pixel is not limited to such a combination of sub-pixels of the three primary colors. In addition to the sub-pixels of the three primary colors, one or more sub-pixels of other colors may be arranged in one pixel. For example, in addition to the three primary colors, a sub-pixel that emits white light for improving luminance may be arranged in one pixel. Also, for example, in addition to the three primary colors, one or more sub-pixels that emit complementary color light for expanding the color reproduction range may be arranged in one pixel.

[0013] In the pixel array 110, scanning lines 211 and 212 are arranged for each pixel row along the row direction (the horizontal direction in FIG. 1) with respect to the array of pixels 101 in m rows and n columns. Also, signal lines 310 are arranged for each pixel column along the column direction (the vertical direction in FIG. 1). The scanning line 211 is respectively connected to the output ends of the corresponding rows of the writing scanning circuit 201. The scanning line 212 is respectively connected to the output ends of the corresponding rows of the light emission driving scanning circuit 202. The signal line 310 is respectively connected to the output ends of the corresponding columns of the signal output circuit 300.

[0014] The pixel array 110 may be formed on a transparent insulating substrate such as a glass substrate or a plastic substrate, for example. In this case, the pixels 101 of the pixel array 110 can be formed using, for example, a low-temperature polysilicon process. However, it is not limited to this. For example, the pixels 101 may be formed using an oxide semiconductor process. Also, for example, the pixel array 110 may be formed on a silicon substrate using a CMOS process.

[0015] The writing scanning circuit 201 can be constituted by, for example, a shift register that sequentially shifts (transfers) start pulses in synchronization with a clock pulse. When writing a video signal to each pixel 101 of the pixel array 110, the writing scanning circuit 201 sequentially supplies a writing scanning signal SEL to the scanning line 211, thereby scanning each pixel 101 of the pixel array 110 in units of rows in order (line sequential scanning).

[0016] The light emission driving scanning circuit 202 can be constituted by, for example, a shift register that sequentially shifts start pulses in synchronization with a clock pulse. The light emission driving scanning circuit 202 supplies a light emission driving signal SW for driving the light emission of the pixel 101 to the scanning line 212 in synchronization with the line sequential scanning by the writing scanning circuit 201. The light emission driving signal SW controls the light emission or non-light emission of the pixel 101.

[0017] The signal output circuit 300 outputs a luminance signal Vsig of the video signal corresponding to the luminance information supplied from the signal source (not shown). For example, a well-known time-division drive circuit configuration can be used as the signal output circuit 300. The time-division drive method, also called the selector method, assigns multiple signal lines as units (sets) to one output terminal of the driver (not shown), which is the signal source. This method sequentially selects these multiple signal lines in a time-division manner, while simultaneously distributing and supplying the video signals output in time series to each output terminal of the driver in a time-division manner to the selected signal lines, thereby driving each signal line 310.

[0018] Taking a pixel array 110 with red, green, and blue subpixels (pixels 101) as an example, the driver supplies the red, green, and blue video signals to the signal output circuit 300 in time series within one horizontal period, using three adjacent pixel rows of red, green, and blue as units. The signal output circuit 300 is configured to include multiplexers corresponding to the three pixel rows of red, green, and blue, and the multiplexers turn on sequentially in a time-division manner to write the red, green, and blue video signals to the corresponding signal lines 310 in a time-division manner.

[0019] As described above, the unit was the three pixel sequences (signal lines) of red, green, and blue, but it is not limited to this. By adopting this time-division drive method (selector method), if the number of time divisions is x (where x is an integer of 2 or more), there is an advantage in that the number of driver outputs and the number of wires between the driver and the signal output circuit 300 can be reduced to 1 / x of the number of signal lines.

[0020] The luminance signal Vsig output from the signal output circuit 300 is written to each pixel 101 of the pixel array 110 row by row via the signal line 310 (line sequential writing).

[0021] Figure 2 is a circuit diagram showing an example configuration of a pixel 101 used in the light-emitting device 100 in this embodiment. As shown in Figure 2, the pixel 101 is equipped with a light-emitting element 121, which is a current-driven electro-optic element whose luminescence changes according to the amount of current flowing through it. The light-emitting element 121 may be, for example, an organic electroluminescent (EL) element. The pixel 101 is also equipped with a drive circuit for driving the light-emitting element 121.

[0022] The drive circuit includes a drive transistor 122, a writing transistor 123, a light emission control transistor 124, and a capacitive element 125. One main terminal (drain electrode) of the drive transistor 122 is connected to the light-emitting element 121, and it supplies a current to the light-emitting element 121 according to the brightness signal Vsig. The writing transistor 123 supplies the brightness signal Vsig to the control terminal (gate electrode) of the drive transistor 122. The light emission control transistor 124 is positioned between the main terminal (source electrode) of the drive transistor 122, which is different from the main terminal connected to the light-emitting element 121, and the supply line 134 that supplies the positive potential PVDD, and controls the light emission or non-emission of the light-emitting element 121. The capacitive element 125 is positioned between the main terminal (source electrode) of the drive transistor 122, which is connected to the light emission control transistor 124, and the control terminal of the drive transistor 122. Furthermore, of the two terminals of the light-emitting element 121, the terminal (cathode electrode) that is not connected to the main terminal (drain electrode) of the drive transistor 122 is connected to a supply line 135 that supplies a common negative potential PVSS to all pixels 101.

[0023] In the configuration shown in Figure 2, a p-channel transistor is used as the drive transistor 122. P-channel transistors are also used for the writing transistor 123 and the light emission control transistor 124. However, the combination of conductivity types for the writing transistor 123 and the light emission control transistor 124 is not limited to this. Either or both of the writing transistor 123 and the light emission control transistor 124 may be n-channel transistors.

[0024] The drive transistor 122 is connected in series with the light-emitting element 121 and supplies a current (drive current) to the light-emitting element 121 corresponding to the brightness signal Vsig. One of the main terminals (drain electrode) of the drive transistor 122 is connected to the terminal (anode electrode) of the light-emitting element 121. In addition, the back gate terminal of the drive transistor 122 is connected to the supply line 133 that supplies the positive potential VDD. In other words, the potential VDD is supplied to the back gate terminal of the drive transistor 122.

[0025] Here, we consider the case where the potential VDD supplied to the back gate terminal of the drive transistor 122 and the potential PVDD supplied from the supply line 134 to the light emission control transistor 124 are at different potentials. However, this is not the only case, and the potentials PVDD and VDD may be at the same potential. A configuration in which the potential VDD supplied to the back gate terminal of the drive transistor 122 is at the same potential as the potential PVDD eliminates the need for the supply line 133 that supplies potential VDD to each pixel 101, thus reducing the wiring pattern. In addition, the circuit for generating potential VDD is not required, which can contribute to reducing the circuit size of the peripheral circuit. However, the potential supplied to the back gate terminal is not limited to this. For example, the potential may be supplied from an external source in the form of a control signal for each row so that different potentials are input during the threshold voltage correction operation and light emission operation described later.

[0026] If the drive transistor 122 is fabricated on an insulator such as a glass substrate or a plastic substrate, the back gate terminal must be made of a conductor such as metal. On the other hand, if the drive transistor 122 is fabricated on a substrate using a conductor or on a Si substrate, for example, the back gate terminal can be realized by applying a potential to the substrate.

[0027] The writing transistor 123 has its control terminal (gate electrode) connected to the scan line 211, one of its two main terminals connected to the signal line 310, and the other main terminal connected to the control terminal of the driving transistor 122. The write scan signal SEL is supplied to the control terminal of the writing transistor 123 from the write scan circuit 201 via the scan line 211.

[0028] The light emission control transistor 124 has its control terminal (gate electrode) connected to the scan line 212, one of its two main terminals (source electrode) connected to the supply line 134 that supplies potential PVDD, and the other main terminal (drain electrode) connected to the main terminal (source electrode) of the drive transistor 122 that is not connected to the light-emitting element 121. The light emission drive signal SW is supplied to the control terminal of the light emission control transistor 124 from the light emission drive scanning circuit 202 via the scan line 212.

[0029] The writing transistor 123 becomes conductive in response to the write scan signal SEL applied to the control terminal via the scan line 211 from the write scan circuit 201. As a result, the writing transistor 123 samples the potential of the video signal (luminance signal Vsig) corresponding to the luminance information supplied from the signal output circuit 300 via the signal line 310 and writes it to the pixel 101. This written luminance signal Vsig is applied to the control terminal of the drive transistor 122 and held in the capacitive element 125.

[0030] The drive transistor 122 receives current from the supply line 134 that supplies the potential PVDD via the light emission control transistor 124, and drives the light-emitting element 121 to emit light by current drive. More specifically, the drive transistor 122 supplies a drive current to the light-emitting element 121 with a current value corresponding to the value of the brightness signal Vsig held in the capacitive element 125, and causes the light-emitting element 121 to emit light by current drive.

[0031] The light emission control transistor 124 becomes conductive in response to the light emission drive signal SW applied to its gate electrode via the scan line 212 from the light emission drive scanning circuit 202, thereby supplying current from the power supply potential PVDD to the drive transistor 122. This enables the drive transistor 122 to drive the light-emitting element 121 to emit light, as described above. In other words, the light emission control transistor 124 functions as a switch for controlling the light emission or non-emission of the light-emitting element 121.

[0032] In this way, the switching operation of the light emission control transistor 124 provides a period during which the light-emitting element 121 is not emitting light (non-emitting period), and the ratio of the light-emitting period to the non-emitting period of the light-emitting element 121 can be controlled (so-called duty cycle control). Duty cycle control reduces afterimage blur caused by the light emission of the pixel 101 throughout one frame period. Therefore, image quality can be improved, especially when displaying moving images.

[0033] Next, the circuit operation of the light-emitting device 100 equipped with the aforementioned pixel 101 will be explained using the timing diagram in Figure 3 and the operation diagrams in Figures 4(a) to 4(f). The timing diagram in Figure 3 shows the changes in the potential of the main terminal (source electrode) connected to the light-emitting control transistor 124 (hereinafter sometimes referred to as the source potential Vs) and the control terminal (gate electrode) (hereinafter sometimes referred to as the gate potential Vg) of the two main terminals of the drive transistor 122, as well as the write scan signal SEL, the light-emitting drive signal SW. In addition, in the operation diagrams in Figures 4(a) to 4(f), the write transistor 123 and the light-emitting control transistor 124 are shown as "switches" for the sake of simplifying the diagrams.

[0034] In the timing diagram of Figure 3, time t1 before the frame of interest corresponds to the light emission period of the light-emitting element 121 in the frame immediately preceding it. During this light emission period of the previous frame, the light emission drive signal SW is in an active state (low potential state), causing the light emission control transistor 124 to conduct (turn on). At this time, the write scan signal SEL is in an inactive state (high potential state), and the write transistor 123 is in a non-conducting (off) state.

[0035] At this time, as shown in Figure 4(a), a drive current Ids corresponding to the gate-source voltage Vgs of the drive transistor 122 is supplied to the light-emitting element 121 via the drive transistor 122 from the supply line 134 that supplies the potential PVDD. As a result, the light-emitting element 121 emits light with a brightness corresponding to the current value of the drive current Ids.

[0036] Next, at time t1, a new frame (frame of interest) of line sequential scanning begins. At time t1, the light emission drive signal SW becomes inactive, causing the light emission control transistor 124 to become non-conductive, as shown in Figure 4(b). As a result, current is no longer supplied to the light-emitting element 121 via the drive transistor 122 from the supply line 134 that supplies the potential PVDD. This causes the light-emitting element 121 to extinguish, resulting in a non-light-emitting period for the frame of interest.

[0037] Furthermore, when current is no longer supplied to the light-emitting element 121, the anode potential of the light-emitting element 121 converges to a potential Vthel+Vcath, which is the sum of the threshold voltage Vthel and the cathode potential Vcath of the light-emitting element 121. At this time, the writing transistor 123 and the light-emitting control transistor 124 remain in a non-conductive state.

[0038] At time t2, a predetermined time has elapsed from time t1, a luminance signal Vsig, which has a voltage reflecting the grayscale, is supplied to the signal line 310 from the signal output circuit. Figure 3 shows the case where the grayscale value of the row of interest is the same as the row to which the luminance signal Vsig was supplied immediately before the row of interest, and the luminance signal Vsig has not changed from the row to which the luminance signal Vsig was supplied immediately before.

[0039] Next, the writing transistor 123 becomes conductive, and the writing period begins in which the luminance signal Vsig is written to the control terminal of the drive transistor 122. The writing period begins with a threshold correction preparation period starting at time t3, during which the write scan signal SEL becomes active and the writing transistor 123 becomes conductive. As a result, as shown in Figure 4(c), the luminance signal Vsig on the signal line 310 is written to the control terminal of the drive transistor 122 via the writing transistor 123.

[0040] Next, at time t4, when the writing transistor 123 is ON, the light-emitting drive signal SW becomes active, and as shown in Figure 4(d), the light-emitting control transistor 124 becomes conductive. When the light-emitting control transistor 124 becomes conductive, current is supplied from the supply line 134 that supplies the potential PVDD to the drive transistor 122, and current flows through the drive transistor 122 according to the gate-source voltage Vgs of the drive transistor 122.

[0041] At this time, the difference |PVDD-Vsig| between the luminance signal Vsig and the potential PVDD is large when the luminance of the light-emitting element 121 is high, and small when it is low. Therefore, the current flowing through the drive transistor 122 at time t4 reflects the luminance of the light-emitting element 121. For example, if the organic EL element does not emit light during the light emission period of the frame of interest, |PVDD-Vsig| will be below the threshold voltage of the drive transistor 122. Therefore, no current flows through the drive transistor 122. In other words, in this case, no current flows from the drive transistor 122 to the light-emitting element 121, and the light-emitting element 121 does not emit light. On the other hand, if the light-emitting element 121 emits light, |PVDD-Vsig| is greater than the threshold voltage of the drive transistor 122.

[0042] Next, at time t5, the light-emitting drive signal SW transitions from an active state to an inactive state, and the light-emitting control transistor 124 becomes non-conductive. At this time, if |PVDD-Vsig| is large, current flows through the path from the capacitive element 125 → drive transistor 122 → light-emitting element 121, as shown in Figure 4(e) (dotted line in the figure).

[0043] As a result, a threshold voltage correction process is performed that changes the source potential Vs in the direction that decreases the gate-source voltage Vgs of the drive transistor 122, while the signal potential Vsig is input to the control terminal of the drive transistor 122. The change in the source potential Vs of the drive transistor 122 is as shown in the timing diagram of Figure 3. As the threshold voltage correction process progresses from time t5, the source potential Vs of the drive transistor 122 decreases from the potential PVDD. This correction process decreases the gate-source voltage Vgs of the drive transistor 122, and at the same time, the difference between the potential of the back gate terminal of the drive transistor 122 (hereinafter sometimes referred to as the back gate potential Vb) and the source potential Vs changes.

[0044] Generally, the threshold voltage of a transistor varies depending on the difference between the back gate potential Vb and the source potential Vs. More specifically, in the case of a p-channel transistor, the absolute value of the threshold voltage shifts to the negative side when the back gate potential Vb is lower than the source potential Vs, and to the positive side when the back gate potential Vb is higher than the source potential Vs.

[0045] In the operation shown in Figure 3, as the threshold voltage correction process is performed, the source potential Vs decreases from the potential PVDD, and the difference between the back gate potential Vb and the source potential Vs, VDD-Vs, increases over time. Therefore, as the source potential Vs decreases, the absolute value of the threshold voltage of the drive transistor 122 shifts to the positive side. After a predetermined time has elapsed, the gate-source potential Vgs of the drive transistor 122 converges to the threshold voltage |Vth+ΔV| considering the back gate potential Vb, and this value is held in the capacitive element 125. Here, the potential Vth is the threshold voltage of the drive transistor 122 when the light-emitting element 121 is emitting light, that is, when the source potential of the drive transistor 122 is potential PVDD and the back gate potential is potential VDD. The potential ΔV is the amount of threshold voltage shift due to the difference between the source potential Vs and the back gate potential Vb during the operation of the threshold voltage correction process.

[0046] Now let's consider the potential δV. As mentioned above, the potential ΔV is a value determined by the difference between the source potential Vs and the back gate potential Vb of the drive transistor 122 during the threshold voltage correction process. However, during the threshold voltage correction process, the source potential Vs of the drive transistor 122 is mainly determined by the gate potential Vg. In other words, the potential ΔV can be said to be determined by the gate potential Vg and the back gate potential Vb. To put it another way, the potential δV can be said to be a value that reflects the luminance signal Vsig.

[0047] This threshold voltage correction process ends at time t6 when the write scan signal SEL transitions from an active state to an inactive state and the write transistor 123 turns off. The duration of this threshold voltage correction process from time t5 to time t6 may be longer than the period during which both the write transistor 123 and the light emission control transistor 124 are on in order to converge the gate-source voltage Vgs of the drive transistor 122 to a voltage of |Vth+ΔV|, as described above. In other words, during the write period (time t3 to time t6) when the write transistor 123 conducts and the brightness signal Vsig is written to the control terminal of the drive transistor 122, the length of the period from when the light emission control transistor 124 changes from a conduction state to a non-conduction state until the write period ends (time t5 to time t6) may be longer than the length of the period during which the light emission control transistor 124 conducts (time t4 to time t5).

[0048] At time t7, a predetermined time has elapsed from time t6, the light-emitting drive signal SW transitions from an inactive state to an active state, and the light-emitting control transistor 124 becomes conductive. When the light-emitting control transistor 124 becomes conductive, current is supplied to the drive transistor 122 from the supply line 134 that supplies the potential PVDD.

[0049] When the light emission control transistor 124 becomes conductive, the source potential Vs of the drive transistor 122 changes to potential PVDD, and therefore the absolute value of the threshold voltage of the drive transistor 122 changes to potential Vth. For this reason, the value |Vth+ΔV| held in the capacitive element 125 is greater than the absolute value of potential Vth, which is the threshold voltage of the drive transistor 122 when the light emission control transistor 124 is conductive. As described above, ΔV is a value that reflects the signal potential Vsig, so the drive transistor 122 supplies a current Ids' corresponding to the gate-source voltage Vgs to the light-emitting element 121, as shown in Figure 4(f). As a result, the light-emitting element 121 emits light and enters the light emission period of the frame of interest.

[0050] Thus, one frame period for displaying one image includes a writing period in which the writing transistor 123 conducts and the luminance signal Vsig is written to the control terminal of the driving transistor 122, and an illumination period in which, after the writing period, the light emission control transistor 124 changes from a non-conductive state to a conductive state and the light-emitting element 121 emits light according to the luminance signal Vsig. The light emission control transistor 124 conducts after the start of this writing period and before the end of the writing period. As a result, the driving circuit for the pixel 101 can correct variations in the threshold voltage of the driving transistor 122 for each pixel 101 with a small number of elements, namely three transistors and one capacitive element. As a result, good image quality can be obtained without luminance variations such as unevenness or streaks caused by variations in the threshold voltage of the driving transistor 122. Furthermore, since the luminance signal Vsig is input to the control terminal of the driving transistor 122 and threshold voltage correction processing is performed, a reference potential used in the threshold correction shown in Patent Document 1 is not required. For this reason, the circuit size of the signal output circuit 300 can be reduced. Furthermore, the power required for charging and discharging the signal line 310, which is caused by the alternating supply of the reference potential and the luminance signal Vsig (signal potential), can be reduced. Therefore, the power consumption of the light-emitting device 100 can be reduced. In addition, because the number of transistors and capacitive elements arranged in the pixel 101 is small, the design of the pixel layout can be made easier, such as when it is necessary to reduce the area of ​​the pixel 101 by increasing the resolution of the pixel array 110. Here, during the writing period, as shown in Figure 3, the light emission control transistor 124 may change from a conductive state to a non-conductive state, and then the writing transistor 123 may become conductive, and the luminance signal Vsig may be written to the control terminal of the drive transistor 122. However, it is not limited to this, and the light emission control transistor 124 may change from a conductive state to a non-conductive state after the writing transistor 123 has become conductive. The above effects can also be obtained by this operation.

[0051] Furthermore, in black display mode, the gate-source voltage Vgs of the drive transistor 122 can be set to a smaller value during the threshold voltage correction preparation period from time t3 to time t5. As a result, the current flowing through the light-emitting element 121 can be reduced during the threshold voltage correction processing period from time t5 to time t6. This suppresses phenomena such as black level floating, and a light-emitting device 100 with high contrast can be obtained.

[0052] Figure 5 shows modified examples of the light-emitting device 100 shown in Figure 1 and the pixel 101 shown in Figure 2. In the configuration shown in Figure 5, scan lines 213 are provided for each pixel row from the initialization scan circuit 203. The scan lines 213 are connected to the output terminals of the corresponding rows of the initialization scan circuit 203.

[0053] The initialization scanning circuit 203 may consist of a shift register or the like that sequentially shifts the start pulse in synchronization with the clock pulse. The initialization scanning circuit 203 supplies an initialization scanning signal RES to the scan line 213 in synchronization with the line sequential scanning by the write scanning circuit 201 to reset the terminal (anode electrode) of the drive transistor 122, one of the two terminals of the light-emitting element 121. The initialization scanning signal RES performs the initialization operation of the anode electrode of the light-emitting element 121.

[0054] Furthermore, in order to perform the initialization operation, as shown in Figure 5, the pixel 101 includes a reset transistor 126 that resets the terminal (anode electrode) of the light-emitting element 121 that is connected to the main terminal of the drive transistor 122 to a predetermined potential VSS. In the configuration shown in Figure 5, a p-channel transistor is used for the reset transistor 126. However, it is not limited to this, and depending on the configuration of the writing transistor 123 and the light emission control transistor 124, the reset transistor 126 may be an n-channel transistor.

[0055] The reset transistor 126 has its control terminal (gate electrode) connected to the scanning line 213, one of the two main terminals connected to the anode electrode of the light-emitting element 121, and the other main terminal connected to the supply line 136 that supplies the potential VSS. Here, when the threshold voltage of the light-emitting element 121 is Vthel and the cathode potential of the light-emitting element 121 (the potential PVSS of the supply line 135) is Vcath, the potential VSS of the supply line 136 is set to satisfy the condition VSS < Vthel + Vcath. Thereby, when the reset transistor 126 is turned on, the potential of the anode electrode of the light-emitting element 121 can be set to a potential at which the light-emitting element 121 does not emit light.

[0056] Here, the case where the potential PVSS supplied to the supply line 135 and the potential VSS supplied from the supply line 136 to the reset transistor 126 are different from each other is considered. However, it is not limited to this, and the potential PVSS and the potential VSS may be the same potential. That is, the potential PVSS supplied to the terminal (cathode electrode) that is not connected to the main terminal of the drive transistor 122 among the two terminals of the light-emitting element and the potential VSS supplied to the reset transistor 126 may be the same potential. A configuration in which the potential VSS is the same as the potential PVSS can reduce the wiring pattern because there is no need for the supply line 136 that supplies the potential VSS to each pixel 101. Also, a circuit for generating the potential VSS becomes unnecessary, contributing to a reduction in the circuit scale of the peripheral circuit.

[0057] The reset transistor 126 becomes conductive prior to the writing period (time t3 to time t6) during the non-emitting period shown in Figure 3, when the luminance signal Vsig is input to the control terminal of the drive transistor 122, and writes the negative potential VSS to the anode electrode of the light-emitting element 121. In other words, the reset transistor 126 may remain conductive throughout the writing period. Due to this operation, the potential of the anode electrode of the light-emitting element 121 becomes potential VSS during the threshold correction preparation and threshold voltage correction processing, so no current flows through the light-emitting element 121, and the phenomenon known as "black floating" does not occur even in black display. As a result, good contrast can be obtained.

[0058] As explained above, in the configuration shown in Figure 5, the pixel 101 has one more transistor than the configuration shown in Figure 2. Also, the inclusion of the reset transistor 126 increases the number of scan lines 213 and initialization scan circuits 203 compared to the configuration shown in Figure 1. However, similar to the above configuration, it is possible to input the luminance signal Vsig to the control terminal of the drive transistor 122 and perform threshold voltage correction processing. Therefore, the reference potential used in the threshold correction shown in Patent Document 1 is not required. As a result, the circuit size of the signal output circuit 300 can be reduced. In addition, the power required for charging and discharging the signal line 310, which is caused by the alternating supply of the reference potential and the luminance signal Vsig (signal potential), can be reduced. Therefore, the power consumption of the light-emitting device 100 can be reduced. Furthermore, the reset transistor 126 suppresses black level floating during the writing period, improving the image quality of the image displayed on the light-emitting device 100.

[0059] Figure 6 shows modified versions of the light-emitting device 100 shown in Figure 1 and the pixel 101 shown in Figure 2. In the configuration shown in Figure 6, the pixel 101 further includes an additional capacitive element 127 positioned between the capacitive element 125 and the supply line 137 that supplies the potential VDD2.

[0060] Here, we consider the case where the potential VDD2 supplied from the supply line 137 and the potential PVDD supplied from the supply line 134 to the light emission control transistor 124 are at different potentials. However, this is not the only case; the potential PVDD and the potential VDD2 may be at the same potential. A configuration in which the potential VDD2 is at the same potential as the potential PVDD or the potential VDD eliminates the need for a supply line 137 to supply the potential VDD2 to each pixel 101, thus reducing the wiring pattern. Furthermore, it eliminates the need for a circuit to generate the potential VDD2, which can contribute to reducing the circuit size of the peripheral circuit.

[0061] The inclusion of the capacitive element 127 allows for a gradual change in the source potential Vs of the drive transistor 122 during threshold voltage correction processing. Furthermore, after the threshold voltage correction processing is completed, the source potential Vs of the drive transistor 122 is maintained by the capacitive element 127 during the period when the light emission control transistor 124 is off (time t6 to time t7). This minimizes the influence of noise from power supply wiring, for example, on the source potential of the drive transistor 122.

[0062] As explained above, in the configuration shown in Figure 6, the pixel 101 has one more capacitive element than the configuration shown in Figure 2. However, as with the above configuration, it is possible to input the luminance signal Vsig to the control terminal of the drive transistor 122 and perform threshold voltage correction processing. Therefore, as with each of the embodiments described above, it is possible to reduce the power consumption of the light-emitting device 100. In addition, as described above, the noise immunity of the luminance signal Vsig is improved, and the image quality of the image displayed on the light-emitting device 100 is improved.

[0063] Figure 7 shows modified examples of the light-emitting device 100 shown in Figure 1 and the pixel 101 shown in Figure 2. As shown in Figure 7, the pixel 101 may also be equipped with a reset transistor 126 and a capacitive element 127, as explained using Figure 5. Even when the pixel 101 has the configuration shown in Figure 7, it is possible to input the luminance signal Vsig to the control terminal of the drive transistor 122 and perform threshold voltage correction processing, similar to the configurations described above. Therefore, as with the embodiments described above, it is possible to reduce the power consumption of the light-emitting device 100. In addition, the reset transistor 126 suppresses black level floating during the writing period, and the capacitive element 127 improves the noise immunity of the luminance signal Vsig, thereby improving the image quality of the image displayed on the light-emitting device 100.

[0064] Figure 8 shows a modified example of the timing of the circuit operation of the light-emitting device 100 shown in Figure 3. The pixel 101 may be any of the configurations shown in Figures 2, 5 to 7. Here, we will explain assuming that the pixel 101 with the configuration shown in Figure 2 is arranged in the light-emitting device 100.

[0065] In the timing diagram shown in Figure 8, after the end of the writing period (times t3 to t6) and before the start of the light emission period indicated by time t9, the writing transistor 123 becomes conductive again, and the brightness signal Vsig is written to the control terminal of the drive transistor 122. In other words, between time t7 and time t8, after a predetermined time has elapsed since the end of the threshold voltage correction processing period, the writing transistor 123 transitions from a non-conductive state to a conductive state, and an additional operation is performed to write the brightness signal Vsig to the control terminal of the drive transistor 122.

[0066] The effect of this additional writing operation will now be explained. As described above, the threshold voltage correction process ends at time t6 when the write scan signal SEL transitions from an active state to an inactive state and the write transistor 123 becomes non-conductive. At that time, as shown in Figure 9(a), the potential change of the write scan signal SEL changes the potential (gate potential Vg) of the control terminal of the drive transistor 122 via the parasitic capacitance Cp1 of the write transistor 123. This potential change becomes larger the steeper the potential change of the write scan signal SEL is. Therefore, as shown in Figure 9(b), the change in the gate potential Vg of the drive transistor 122 is larger on the side of the pixel array 110 closer to the write scan circuit 201 (left side in Figure 1, hereafter sometimes referred to as the near end), and smaller on the far side (right side in Figure 1, hereafter sometimes referred to as the far end).

[0067] A capacitive element 125 is connected between the gate and source of the drive transistor 122, and the change in the gate potential Vg of the drive transistor 122 is input to the source potential Vs via the capacitive element 125. At this time, a parasitic capacitance Cp2 exists between the source electrode of the drive transistor 122 and, for example, the back gate terminal, so the gate-source voltage Vgs of the drive transistor 122 changes with the potential change of the write scan signal SEL. If the write transistor 123 is a p-channel type transistor, the potential of the write scan signal SEL changes from a low potential to a high potential, so the gate-source voltage Vgs of the drive transistor 122 becomes smaller. On the other hand, if the write transistor 123 is an n-channel type transistor, the potential of the write scan signal SEL changes from a high potential to a low potential, so the gate-source voltage Vgs of the drive transistor 122 becomes larger.

[0068] This operation causes a small current to flow through the drive transistor 122, corresponding to the changed gate-source voltage Vgs of the drive transistor 122. As described above, this current differs between the near-end and far-end sides of the pixel array 110. For example, if the writing transistor 123 is a p-channel type transistor, the gate-source voltage Vgs of the drive transistor 122 on the near-end side is smaller than the gate-source voltage Vgs of the drive transistor 122 on the far-end side. Therefore, the current flowing through the drive transistor 122 on the near-end side is smaller than the current flowing through the drive transistor 122 on the far-end side. Due to this current, the gate-source voltage Vgs of the drive transistor 122 gradually decreases from time t6, with the decrease being greater on the far-end side than on the near-end side.

[0069] At time t7, after a predetermined time has elapsed, the write scan signal SEL transitions from an inactive state to an active state, causing the write transistor 123 to conduct, and the brightness signal Vsig is input again to the control terminal of the drive transistor 122. At this time, the gate-source voltage Vgs of the drive transistor 122 has decreased due to the current mentioned above, so the gate potential Vg of the drive transistor 122 changes to the signal potential Vsig, and the amount of change in potential is input to the source electrode via the capacitive element 125. At this time, there is a parasitic capacitance Cp2 between the source electrode of the drive transistor 122 and, for example, the back gate terminal, so this operation causes the gate-source voltage Vgs of the drive transistor 122 to change. This amount of change is larger if the gate potential Vg of the drive transistor 122 just before the write transistor 123 conducts is small, and therefore it is larger on the far end side where the decrease in the gate potential Vg of the drive transistor 122 due to the current is large.

[0070] Subsequently, at time t8, the write scan signal SEL transitions from an active state to an inactive state, the write transistor 123 becomes non-conductive, and the gate-source voltage Vgs of the drive transistor 122 changes, similar to time t6. The amount of change is such that the gate-source voltage Vgs of the drive transistor 122 becomes smaller at the near end, but at time t7 the gate-source voltage Vgs is smaller at the far end, so at time t8 the change is in the direction of reducing the difference, and overall the gate-source voltage Vgs of the drive transistor 122 becomes nearly constant at both the near and far ends.

[0071] As described above, the threshold voltage correction processing period from time t5 to time t6 is used to converge the gate-source voltage Vgs of the drive transistor 122 to a voltage of |Vth+ΔV|. For this purpose, it is longer than the period from time t4 to time t5, during which both the write transistor 123 and the light emission control transistor 124 are conducting. On the other hand, the writing period of the side luminance signal Vsig, which takes place from time t7 to time t8, is the operation of inputting the luminance signal Vsig to the control terminal of the drive transistor 122, and therefore may be shorter than the threshold voltage correction processing period. Also, for example, the length of the period (time t7 to time t8) during which the write transistor 123 conducts again after the end of the writing period (time t3 to time t6) and before the start of the light emission period may be shorter than the length of the writing period.

[0072] Even when the operation shown in Figure 8 is performed, the light-emitting device 100 can input the luminance signal Vsig to the control terminal of the drive transistor 122 and perform threshold voltage correction processing, similar to the configurations described above. Therefore, as with the embodiments described above, it becomes possible to reduce the power consumption of the light-emitting device 100.

[0073] Furthermore, after the threshold voltage correction process, the write transistor 123 is re-activated before entering the light emission period. This corrects the difference in the gate-source voltage Vgs of the drive transistor 122 caused by the potential change of the write scan signal SEL at the near and far ends of the pixel array 110. As a result, brightness variations such as shading are suppressed, and the image quality displayed on the light-emitting device 100 is improved.

[0074] Furthermore, as described above, the operation shown in Figure 8 is not limited to the light-emitting device 100 in which the pixel 101 having the configuration shown in Figure 2 is arranged in the pixel array 110. The operation shown in Figure 8 can be applied to the light-emitting device 100 in which the pixel 101 having the configuration described using Figures 5 to 7 is arranged in the pixel array 110.

[0075] Furthermore, although an organic EL element was mentioned above as the light-emitting element 121, it is not limited to this. The light-emitting element 121 can be applied to all light-emitting devices that use current-driven electro-optic elements (light-emitting elements) in which the luminescence changes according to the current value flowing through the element, such as inorganic EL elements, LED elements, and semiconductor laser elements.

[0076] Here, examples of applications of the light-emitting device 100 of this embodiment applied to display devices, photoelectric converters, electronic devices, lighting devices, mobile devices, and wearable devices will be explained using Figures 10 to 16(a) and 16(b).

[0077] Figure 13 is a schematic diagram showing an example of a display device using the light-emitting device 100 of this embodiment. The display device 1000 may have 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. Flexible printed circuits FPCs 1002 and 1004 are connected to the touch panel 1003 and the display panel 1005. Active elements such as transistors are arranged on the circuit board 1007. The battery 1008 does not need to be provided if the display device 1000 is not a portable device, and even if it is a portable device, it does not need to be provided in this position. The light-emitting device 100 of this embodiment can be applied to the display panel 1005. The display area of ​​the light-emitting device 100, which functions as the display panel 1005, is connected to and operates with active elements such as transistors arranged on the circuit board 1007.

[0078] The display device 1000 shown in Figure 10 may be used as the display unit of a photoelectric conversion device (imaging device) having an optical unit with multiple lenses and an image sensor that receives light passing through the optical unit and converts it into an electrical signal. The photoelectric conversion device may have a display unit that displays information acquired by the image sensor. The display unit may be an external display unit exposed to the outside of the photoelectric conversion device, or a display unit located inside the viewfinder. The photoelectric conversion device may be a digital camera or a digital video camera.

[0079] Figure 11 is a schematic diagram showing an example of a photoelectric converter using the light-emitting device 100 of this embodiment. The photoelectric converter 1100 may have a viewfinder 1101, a rear display 1102, an operating unit 1103, and a housing 1104. The photoelectric converter 1100 may also be called an imaging device. The light-emitting device 100 of this embodiment can be applied to the display unit, which is the viewfinder 1101 or the rear display 1102. In this case, the light-emitting device 100 may display not only the image to be captured, but also environmental information, imaging instructions, etc. Environmental information may include the intensity of ambient light, the direction of ambient light, the speed at which the subject is moving, and the possibility that the subject may be obscured by an obstacle.

[0080] Since the optimal timing for imaging is often very short, it is desirable to display information as quickly as possible. Therefore, a light-emitting device 100 containing an organic light-emitting material such as an organic EL element in its light-emitting layer may be used in the viewfinder 1101 or the rear display 1102. This is because organic light-emitting materials have a fast response speed. A light-emitting device 100 using an organic light-emitting material is more suitable than a liquid crystal display device for these devices where display speed is required.

[0081] The photoelectric converter 1100 has an optical section (not shown). The optical section has multiple lenses, and the light that passes through the optical section is imaged onto a photoelectric converter element (not shown) housed in a light-receiving housing 1104. The focus can be adjusted by adjusting the relative positions of the multiple lenses. This operation can also be performed automatically.

[0082] The light-emitting device 100 may be applied to the display section of an electronic device. In that case, it may have both a display function and an operating function. Examples of portable terminals include mobile phones such as smartphones, tablets, and head-mounted displays.

[0083] Figure 12 is a schematic diagram showing an example of an electronic device using the light-emitting device 100 of this 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 response unit. The operation unit 1202 may also be a biometric recognition unit that recognizes fingerprints to unlock, etc. A portable device having a communication unit can also be called a communication device. The light-emitting device 100 of this embodiment can be applied to the display unit 1201.

[0084] Figures 13(a) and 13(b) are schematic diagrams showing an example of a display device using the light-emitting device 100 of this embodiment. Figure 13(a) is 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 100 of this embodiment can be applied to the display unit 1302. The display device 1300 may also 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 Figure 13(a). For example, the lower edge of the frame 1301 may also serve as the base 1303. Also, 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.

[0085] Figure 13(b) is a schematic diagram showing another example of a display device using the light-emitting device 100 of this embodiment. The display device 1310 in Figure 13(b) is configured to be foldable 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 100 of this 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 device without seams. The first display unit 1311 and the second display unit 1312 can be separated by a bending point. The first display unit 1311 and the second display unit 1312 may each display different images, or they may display a single image together.

[0086] Figure 14 is a schematic diagram showing an example of a lighting device using the light-emitting device 100 of this 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 100 of this 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 the light from the light source, such as for lighting up, and deliver light over a wide area. A cover may be provided on the outermost part if necessary. The lighting device 1400 may have both the optical film 1404 and the light diffusion unit 1405, or it may have only one of them.

[0087] The lighting device 1400 is, for example, a device for illuminating a room. The lighting device 1400 may emit white light, daylight white light, or any other color from blue to red. It may have a dimming circuit for adjusting the brightness of these colors. The lighting device 1400 may have a power supply circuit connected to the light-emitting device 100, which functions as a light source 1402. The power supply circuit is a circuit that converts AC voltage to DC voltage. White light has a color temperature of 4200K, and daylight white light 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 dissipation section. The heat dissipation section releases heat from inside the device to the outside, and examples include metals with high specific heat and liquid silicon.

[0088] Figure 15 is a schematic diagram of an automobile having a taillight, which is an example of a vehicle light fixture using the light-emitting device 100 of this embodiment. The automobile 1500 may have a taillight 1501, and the taillight 1501 may be illuminated when the brakes are applied or otherwise. The light-emitting device 100 of this embodiment may also be used as a headlight for a vehicle. The automobile is an example of a mobile body, and the mobile body may be a ship, drone, aircraft, railway vehicle, industrial robot, etc. The mobile body may have a body and a light fixture installed thereon. The light fixture may indicate the current position of the body.

[0089] The light-emitting device 100 of this embodiment can be applied to the tail lamp 1501. The tail lamp 1501 may have a protective member to protect the light-emitting device 100 that functions as a tail lamp 1501. The protective member can be made of any material as long as it has a reasonably high strength and is transparent, but it may be made of polycarbonate or the like. The protective member may also be made of polycarbonate mixed with a frangic acid derivative, an acrylonitrile derivative, or the like.

[0090] The automobile 1500 may have a body 1503 and windows 1502 attached thereto. The windows may be for checking the front and rear of the automobile, or they may be transparent displays. The light-emitting device 100 of this embodiment may be used as the transparent display. In this case, the constituent materials such as electrodes of the light-emitting device 100 are made of transparent materials.

[0091] Further application examples of the light-emitting device 100 of this embodiment will be described with reference to Figures 16(a) and 16(b). The light-emitting device 100 can be applied to systems that can be worn as wearable devices such as smart glasses, head-mounted displays (HMDs), and smart contact lenses. The imaging display device used in such application examples has an imaging device capable of photoelectric conversion of visible light and a light-emitting device capable of emitting visible light.

[0092] Figure 16(a) illustrates a pair of glasses 1600 (smart glasses) according to one application example. An imaging device 1602, such as a CMOS sensor or SPAD, is provided on the front surface side of the lens 1601 of the glasses 1600. In addition, the light-emitting device 100 of this embodiment is provided on the back surface side of the lens 1601.

[0093] The eyeglasses 1600 further include a control device 1603. The control device 1603 functions as a power supply that provides power to the imaging device 1602 and the light-emitting device 100 according to each embodiment. The control device 1603 also controls the operation of the imaging device 1602 and the light-emitting device 100. The lens 1601 has an optical system formed therein for focusing light onto the imaging device 1602.

[0094] Figure 16(b) illustrates a pair of glasses 1610 (smart glasses) according to one application example. The glasses 1610 have a control device 1612, which is equipped with an imaging device equivalent to an imaging device 1602 and a light-emitting device 100. The lens 1611 has an optical system formed to project the light emitted from the imaging device and the light-emitting device 100 within the control device 1612, and an image is projected onto the lens 1611. The control device 1612 functions as a power supply to provide power to the imaging device and the light-emitting device 100, and also controls the operation of the imaging device and the light-emitting device 100. The control device 1612 may have a gaze detection unit that detects the wearer's gaze. Gaze detection may use infrared light. The infrared light-emitting unit emits infrared light towards the eyeball of the user who is gazing at the displayed image. The imaging unit, which has a photodetector, detects the reflected light from the eyeball of the emitted infrared light, thereby obtaining an image of the eyeball. By having a reduction mechanism that reduces the amount of light transmitted from the infrared light-emitting part to the display part in a planar view, the degradation of image quality is reduced.

[0095] The user's gaze towards the displayed image is detected from an image of the eyeball obtained by imaging with infrared light. Any known method can be applied to gaze detection using an image of the eyeball. For example, a gaze detection method based on the Purkinje image obtained by the reflection of the irradiated light from the cornea can be used.

[0096] More specifically, gaze detection processing is performed based on the pupil-corneal reflection method. Using the pupil-corneal reflection method, a gaze vector representing the orientation (rotation angle) of the eyeball is calculated based on the pupil image and Purkinje image contained in the captured image of the eyeball, thereby detecting the user's gaze.

[0097] A light-emitting device 100 according to one embodiment of the present invention has an imaging device having a light-receiving element, and may control the displayed image based on the user's gaze information from the imaging device.

[0098] Specifically, the light-emitting device 100 determines a first field of view area that the user is fixated on, and a second field of view area other than the first field of view area, based on gaze information. The first and second field of view areas may be determined by the control device of the light-emitting device 100, or they may be determined by an external control device and received by the device. In the display area of ​​the light-emitting device 100, 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.

[0099] Furthermore, the display area has a first display area and a second display area different from the first display area, and based on gaze information, the area with higher priority is determined from the first display area and the second display area. The first display area and the second display area may be determined by the control device of the light-emitting device 100, or they 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 the areas other than the high-priority area. In other words, the resolution of the area with relatively lower priority may be lowered.

[0100] AI may be used to determine the first field of view area and high-priority areas. The AI ​​may be a model configured to estimate the angle of line of sight and the distance to the target object at the end of the line of sight from the image of the eye, using the image of the eye and the direction the eye was actually looking in the image as training data. The AI ​​program may be owned by the light-emitting device 100, the imaging device, or an external device. If it is owned by an external device, it is transmitted to the light-emitting device 100 via communication.

[0101] When display control is based on visual detection, this method is preferably applicable to smart glasses that further include an imaging device for capturing images of the surrounding environment. The smart glasses can display the captured external information in real time.

[0102] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0103] 100: Light-emitting device, 101: Pixel, 121: Light-emitting element, 122: Driving transistor, 123: Writing transistor, 124: Light-emitting control transistor, 125: Capacitive element

Claims

1. A light-emitting device having a pixel comprising a light-emitting element, a drive transistor whose first main terminal is connected to the light-emitting element and which supplies a current corresponding to a brightness signal to the light-emitting element, a light-emitting control transistor disposed between the second main terminal of the drive transistor and a supply line that supplies a first potential and which controls the light emission or non-emission of the light-emitting element, a write transistor for supplying the brightness signal to the control terminal of the drive transistor, and a capacitive element disposed between the second main terminal and the control terminal, A second potential is supplied to the back gate terminal of the aforementioned drive transistor. One frame period includes a writing period in which the writing transistor conducts and the brightness signal is written to the control terminal, and a light emission period in which, after the writing period, the light emission control transistor changes from a non-conductive state to a conductive state and the light-emitting element emits light according to the brightness signal. A light-emitting device characterized in that, after the start of the writing period and before the end of the writing period, while the brightness signal is input to the control terminal of the drive transistor, the light-emitting control transistor changes from a conductive state to a non-conductive state.

2. The light-emitting device according to claim 1, characterized in that the length of the period from when the light-emitting control transistor changes from a conductive state to a non-conductive state during the writing period until the end of the writing period is longer than the length of the period during which the light-emitting control transistor is conductive during the writing period.

3. The light-emitting device according to claim 1 or 2, characterized in that the first potential and the second potential are the same potential.

4. The light-emitting device according to any one of claims 1 to 3, characterized in that, after the end of the writing period and before the start of the light-emitting period, the writing transistor is again made conductive and the brightness signal is written to the control terminal.

5. The light-emitting device according to claim 4, characterized in that the length of the period during which the writing transistor conducts again after the end of the writing period and before the start of the light-emitting period is shorter than the length of the writing period.

6. The light-emitting device according to claim 4 or 5, characterized in that the length of the period during which the writing transistor conducts again after the end of the writing period and before the start of the light-emitting period is shorter than the length of the period from when the light-emitting control transistor changes from a conductive state to a non-conductive state during the writing period until the end of the writing period.

7. The light-emitting device according to any one of claims 1 to 6, characterized in that the pixel further includes a reset transistor that resets the terminal of the light-emitting element that is connected to the first main terminal to a third potential.

8. The light-emitting device according to claim 7, characterized in that the reset transistor is in a conductive state during the aforementioned writing period.

9. The light-emitting device according to claim 7 or 8, characterized in that the potential supplied to the terminal of the light-emitting element that is not connected to the first main terminal is the same as the third potential.

10. The light-emitting device according to any one of claims 1 to 9, characterized in that the pixel further includes an additional capacitive element disposed between the capacitive element and a supply line that supplies a fourth potential.

11. The light-emitting device according to claim 10, characterized in that the first potential and the fourth potential are the same potential.

12. The light-emitting device according to any one of claims 1 to 11, characterized in that the driving transistor is a p-channel type transistor.

13. The light-emitting device according to any one of claims 1 to 12, characterized in that the length of the period from the end of the writing period to the start of the light-emitting period is longer than the length of the writing period.

14. Having a signal line connected to the writing transistor and into which the brightness signal is input, The light-emitting device according to any one of claims 1 to 13, characterized in that only the luminance signal is input to the signal line.

15. A display device comprising a light-emitting device according to any one of claims 1 to 14, and an active element connected to the light-emitting device.

16. It comprises an optical unit having multiple lenses, an image sensor that receives light that has passed through the optical unit, and a display unit that displays an image. The photoelectric converter is characterized in that the display unit is a display unit that displays an image captured by the image sensor, and has a light-emitting device according to any one of claims 1 to 14.

17. It comprises a housing on which a display unit is provided, and a communication unit provided in the housing for communicating with the outside, The display unit is an electronic device characterized by having a light-emitting device according to any one of claims 1 to 14.

18. A lighting device having a light source and at least one of a light diffusing section and an optical film, The lighting device is characterized in that the light source has a light-emitting device according to any one of claims 1 to 14.

19. A mobile body having an aircraft body and a lighting fixture provided on the aircraft body, The aforementioned light fixture is a mobile body characterized by having a light-emitting device according to any one of claims 1 to 14.

20. A wearable device having a display device for displaying images, The wearable device is characterized in that the display device has a light-emitting device according to any one of claims 1 to 14.

Images