Light-emitting device and method for driving light-emitting device

Abstract

When a light-emitting device such as a display is configured from a multicolor light-emitting semiconductor light-emitting element, appropriate light emission control can be achieved. A light-emitting device (100) is provided with: a display unit (10) in which a plurality of pixels (12) are configured by arranging a plurality of first light-emitting elements (11A) capable of emitting a first light-emitting color and a plurality of second light-emitting elements (11B) capable of emitting a second light-emitting color different from the first light-emitting color in a predetermined pattern; and a lighting control unit (50) that supplies a drive current to each of the plurality of first light-emitting elements (11A) and the plurality of second light-emitting elements (11B), and controls a light-emitting period. The second light-emitting element (11B) can control the emission color according to the drive current, and the lighting control unit (50) is driven so as to divide a frame in which the plurality of first light-emitting elements (11A) and the plurality of second light-emitting elements (11B) emit light into a first sub-frame in which the plurality of first light-emitting elements (11A) emit light, and a second sub-frame in which the plurality of second light-emitting elements (11B) emit light.

Description

Technical Field

[0001] The present disclosure relates to a light-emitting device and a driving method thereof. Background Art

[0002] Displays or surface light-emitting devices using semiconductor light-emitting elements such as LEDs and LDs have been applied. Here, in order to manufacture a full-color LED display, it is generally necessary to arrange at least three-color sub-pixels of RGB for each pixel. However, in such a structure, it is necessary to provide more than three times the number of sub-pixels of the number of pixels, so it is not suitable for high definition, and there are problems of high cost and low yield due to the increase in the number of LEDs.

[0003] In response to this, a micro LED display that makes one LED element emit multi-color light has been disclosed (Patent Document 1). However, when a display is constituted by such multi-color light-emitting micro LEDs, an actual circuit structure and a driving method have not been disclosed. For example, in the prior art, it is not easy to control in such a way that the multi-color light-emitting micro LEDs emit light in all chromaticity ranges of RGB.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-52168 Summary of the Invention

[0007] Technical Problem to be Solved by the Invention

[0008] One object of the present disclosure is to provide a light-emitting device and a driving method thereof that can achieve appropriate light-emitting color control when a light-emitting device such as a display is constituted by multi-color light-emitting semiconductor light-emitting elements.

[0009] Technical Solution for Solving the Technical Problem

[0010] A light-emitting device according to one aspect of the present disclosure includes: a display unit that constitutes a plurality of pixels by arranging a plurality of first light-emitting elements capable of emitting a first light-emitting color and a plurality of second light-emitting elements capable of emitting a second light-emitting color different from the first light-emitting color in a predetermined pattern; a lighting control unit that supplies drive currents to the plurality of first light-emitting elements and the plurality of second light-emitting elements respectively and controls a lighting period, and the second light-emitting element can control a light-emitting color according to the drive current, and the lighting control unit drives in such a way that one frame in which the plurality of first light-emitting elements and the plurality of second light-emitting elements emit light is divided into a first sub-frame in which the plurality of first light-emitting elements emit light respectively and a second sub-frame in which the plurality of second light-emitting elements emit light respectively.

[0011] In addition, in the driving method of a light-emitting device in other aspects, the light-emitting device includes: a display unit that forms a plurality of pixels by arranging a plurality of first light-emitting elements capable of emitting a first light-emitting color and a plurality of second light-emitting elements capable of emitting a second light-emitting color different from the first light-emitting color and capable of controlling the light-emitting color according to a driving current in a prescribed pattern; and a lighting control unit that supplies driving currents to the plurality of first light-emitting elements and the plurality of second light-emitting elements respectively and controls the light-emitting period. The driving method of the light-emitting device includes the following steps: the lighting control unit drives in such a way that one frame for causing the plurality of first light-emitting elements and the plurality of second light-emitting elements to emit light is divided into a first sub-frame in which the plurality of first light-emitting elements emit light respectively and a second sub-frame in which the plurality of second light-emitting elements emit light respectively.

[0012] Advantages of the Invention

[0013] According to the above structure, by combining the first light-emitting color and the second light-emitting color that becomes different light-emitting colors according to the driving current, it is possible to obtain the advantages of being able to perform multicolor light emission such as full color and being able to achieve simpler light-emitting control. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a block diagram showing the light-emitting device of Embodiment 1.

[0015] Figure 2 is a timing chart for lighting and driving the first light-emitting element and the second light-emitting element.

[0016] Figure 3 is a block diagram showing an example of setting a first control circuit and a second control circuit in a pixel circuit.

[0017] Figure 4 is a block diagram showing the display unit of the light-emitting device of Embodiment 1 with an enlarged view.

[0018] Figure 5 is a schematic cross-sectional view showing an example of the element structure of a light-emitting element.

[0019] Figure 6 is a schematic diagram showing the lighting image of the first sub-frame.

[0020] Figure 7 is a schematic diagram showing the lighting image of the second sub-frame.

[0021] Figure 8 is a functional block diagram showing a method for determining a driving current value and a PWM light-emitting period.

[0022] Figure 9 is for showing in Figure 8 the chromaticity diagram of the steps for determining the light-emitting chromaticity.

[0023] Figure 10A It is a schematic diagram of one pixel of the light-emitting device according to Embodiment 1. Figure 10B It is a schematic diagram of one pixel of the light-emitting device according to Embodiment 2.

[0024] Description of Reference Numerals

[0025] 100, 200: Light-emitting device

[0026] 2: n-type semiconductor layer

[0027] 3: Active layer

[0028] 4: p-type semiconductor layer

[0029] 5: n-side electrode

[0030] 6: p-side electrode

[0031] 8: Pixel driving circuit

[0032] 9: Power supply line

[0033] 10: Display unit

[0034] 11: Light-emitting element

[0035] 11A, 11A’: First light-emitting element

[0036] 11B: Second light-emitting element

[0037] 12, 12B, 12D: Pixel

[0038] 12A: First sub-pixel

[0039] 12B: Second sub-pixel

[0040] 14: Pixel circuit

[0041] 14A: First sub-pixel circuit

[0042] 14B: Second sub-pixel circuit

[0043] 20: Scanning unit

[0044] 30: Driving unit

[0045] 50, 50A, 50B: Lighting control unit

[0046] 51, 51A, 51B: First control circuit

[0047] 52, 52A, 52B: Second control circuit

[0048] 60: Driving control unit

[0049] 70: Information holding unit

[0050] WS: Write Scan Line

[0051] WS1: Power Control Signal Write Scan Line

[0052] WS2: Analog Image Signal Write Scan Line

[0053] SL: Signal Line

[0054] SL1: Power Control Signal Line

[0055] SL2: Analog Image Signal Line Detailed Implementation Manner

[0056] Hereinafter, the present disclosure will be described in more detail based on the accompanying drawings. In addition, in the following description, terms indicating specific directions and positions (for example, "up", "down", and other terms including these terms) are used as needed, but the use of these terms is for easy understanding of the invention with reference to the drawings, and does not limit the technical scope of the present disclosure according to the meanings of these terms. In addition, parts with the same reference numerals appearing in multiple drawings represent the same or equivalent parts or components.

[0057] Furthermore, the embodiments shown below represent specific examples of the technical idea of the present disclosure, and the present disclosure is not limited to the following content. In addition, the dimensions, materials, shapes, relative configurations, etc. of the constituent components described below are not intended to limit the scope of the present disclosure only thereto, but are intended to be illustrative as long as there is no specific description. In addition, the content described in one embodiment or example can also be applied to other embodiments or examples. In addition, the sizes or positional relationships of the components shown in the drawings are sometimes exaggerated for clarity of explanation.

[0058] [Embodiment 1]

[0059] Figure 1 The block diagram showing the light-emitting device 100 of Embodiment 1. The light-emitting device 100 shown in this figure includes a display unit 10, a driving unit 30, a lighting control unit 50, an information holding unit 70, a scanning unit 20, and a driving control unit 60.

[0060] The display unit 10 arranges a plurality of first light-emitting elements 11A and a plurality of second light-emitting elements 11B in a prescribed pattern to form a plurality of pixels 12. Specifically, the plurality of first light-emitting elements 11A and second light-emitting elements 11B are arranged in a row-column shape or a matrix shape. Sometimes, the period during which one frame amount of image data is displayed on a screen formed by pixels 12 arranged in a matrix shape is referred to as a vertical scanning period, and the period obtained by dividing the vertical scanning period by the number of rows of the screen is referred to as a horizontal scanning period. For example, during the horizontal scanning period, a voltage value for power control of pixels 12 arranged in the row direction (X-axis direction) is set, and a voltage value for simulating image data is set. In addition, during the vertical scanning period, the scanning unit 20 that scans the pixels 12 is sequentially shifted in the column direction (Y-axis direction). Figure 1 The light-emitting device 100 adopts an active matrix driving method as the lighting driving method for lighting each pixel 12.

[0061] In addition, each pixel 12 is composed of one or more first light-emitting elements 11A and one or more second light-emitting elements 11B. In Figure 1 the example shown, one pixel 12 is composed of one first light-emitting element 11A and one second light-emitting element 11B. However, the present disclosure is not limited to this structure, and one pixel may also be composed of a plurality of first light-emitting elements or a plurality of second light-emitting elements. By using a plurality of first light-emitting elements or second light-emitting elements, the light-emitting luminance per pixel can be increased.

[0062] The first light-emitting element 11A can emit a first light-emitting color. The first light-emitting color is, for example, blue light.

[0063] The second light-emitting element 11B can emit a second light-emitting color different from the first light-emitting color. This second light-emitting element 11B can control the light-emitting color according to its driving current. Such a second light-emitting element 11B can suitably utilize a multi-color light-emitting type light-emitting wavelength variable LED. The second light-emitting color is, for example, variable from green light to red light. In addition, in the present disclosure, the first light-emitting element 11A and the second light-emitting element 11B are sometimes collectively referred to as the light-emitting element 11.

[0064] (Lighting control unit 50)

[0065] The lighting control unit 50 supplies driving currents to the plurality of first light-emitting elements 11A and the plurality of second light-emitting elements 11B respectively, and controls the light-emitting period. In Figure 1 the example shown in the enlarged view, the lighting control unit 50 is connected to the power supply line 9 extending in the horizontal direction and the write scan line WS. The lighting control unit 50 is driven by receiving power supply from the power supply line 9, and receives a power control signal or an analog image signal via the write scan line WS. On the other hand, the lighting control unit 50 is also connected to the signal line SL extending in the vertical direction, and receives a power control signal or an analog image signal.

[0066] The lighting control unit 50 divides one frame for causing a plurality of first light-emitting elements 11A and a plurality of second light-emitting elements 11B to emit light into a first sub-frame for causing the plurality of first light-emitting elements 11A to emit light respectively and a second sub-frame for causing the plurality of second light-emitting elements 11B to emit light respectively, and drives them. For example, the first sub-frame is set as a B sub-frame that emits blue light, and the second sub-frame is set as an RG sub-frame that emits green light to red light.

[0067] According to such a structure, the light-emitting device 100 capable of variably controlling the emission color can be efficiently driven. In particular, even if the second light-emitting element 11B that can emit different emission colors according to the drive current is not controlled for light emission in the entire RGB range region, the light emission control is limited to, for example, only a limited wavelength region such as green light to red light. Thus, full-color light emission for each pixel can be performed in combination with the first emission color of the first light-emitting element 11A, and simpler light emission control can be achieved.

[0068] In a multi-color light-emitting type LED in which the emission wavelength is variable, the emission color changes according to the drive current. In other words, the amount of drive current at this time varies greatly depending on the emission color, and the emission luminance also varies greatly. For example, when it is desired to appropriately adjust the luminance and emission color using a multi-color light-emitting type LED element to display short-wavelength light and long-wavelength light on a display, it is necessary to control the emission period within a range of about 3 to 30 times according to the emission wavelength. Therefore, in order to reduce useless non-emission periods and obtain sufficient emission luminance, it is preferable to adopt field-sequential driving in which each emission color is lit in a different sub-frame.

[0069] However, if field-sequential driving in which the emission color is changed for each sub-frame is performed, color breakup occurs particularly in animations, and there is a problem that the image quality deteriorates significantly. That is, in the case of field-sequential driving, since the pixels are active matrix, after writing display data to the row selected by scanning, it is necessary to ensure a certain emission time. Therefore, the scanning period and the emission period of each row are defined independently. Therefore, in the field sequence, the light emission is not in units of rows but in units of sub-fields, but as a side effect, there is a problem of color breakup.

[0070] In contrast, in the light-emitting device 100 of Embodiment 1, the light-emitting element 11 constituting one pixel is composed of a first light-emitting element 11A capable of emitting light of a first emission color and a second light-emitting element 11B capable of emitting light of a second emission color, and the second emission color is made variable, thereby suppressing the range of required color changes. In addition, by using only blue light with low human visual sensitivity as another sub-frame, color breakup is suppressed. Hereinafter, a detailed description will be given.

[0071] (The first light-emitting element 11A and the second light-emitting element 11B)

[0072] The first light-emitting element 11A and the second light-emitting element 11B can preferably use semiconductor light-emitting elements such as light-emitting diodes (LEDs) or semiconductor lasers (LDs). For the LED, an LED configured with one or more semiconductor laminate layers having a light-emitting portion (hereinafter, also simply referred to as "semiconductor laminate") can be used. The semiconductor laminate has light-emitting characteristics. Such a semiconductor laminate uses a structure in which multiple semiconductor layers such as ZnS, SiC, GaN, GaP, InN, AlN, ZnSe, GaAsP, GaAlAs, InGaN, GaAlN, AlInGaP, and AlInGaN are laminated on a substrate by a liquid-phase growth method, HVPE method, or MOCVD method, and an active layer is formed on any one of the semiconductor layers. By selecting the material of the semiconductor layer and its mixed crystal ratio, the emission wavelength from the active layer can be selected from ultraviolet light to infrared light in various ways. In particular, when a display device that can be appropriately used outdoors is provided, a semiconductor laminate capable of emitting light with high brightness is required. Therefore, a nitride semiconductor is preferably selected as the material of the light-emitting portion that emits light with high brightness. For example, as the material of the light-emitting portion, In X Al Y Ga 1-X-Y N (0 ≤ X ≤ 1, 0 ≤ Y ≤ 1, X + Y ≤ 1), etc.

[0073] In Embodiment 1, as each of the first light-emitting element 11A and the second light-emitting element 11B, a semiconductor light-emitting element such as a light-emitting diode or a semiconductor laser is used. In addition, a micro LED can also be used as the light-emitting diode. Considering the chip size of 5 μm to 100 μm, luminous efficiency, etc., the micro LED is preferably 10 μm to 50 μm.

[0074] The first light-emitting element 11A fixes the first emission color as its emission color. On the other hand, the second light-emitting element 11B makes the second emission color variable. The second light-emitting element 11B emits different emission colors according to the drive current. For example, if it is driven with a first drive current, it emits light with a first emission wavelength, for example, red, and if it is driven with a second drive current larger than the first drive current, it emits light with a second emission wavelength shorter than the first emission wavelength, for example, green.

[0075] Each of the first light-emitting element 11A and the second light-emitting element 11B is connected to a plurality of common lines and a plurality of drive lines. By connecting the first light-emitting element 11A and the second light-emitting element 11B to one of the plurality of common lines and one of the plurality of drive lines respectively and arranging them in a row and column pattern, the display unit 10 is constituted.

[0076] (Scanning unit 20)

[0077] The scanning unit 20 is provided in a column further to the left of the leftmost column of the pixels 12 arranged in a matrix. The scanning unit 20 may also be provided in a column further to the right of the rightmost column of the pixels 12 arranged in a matrix. Additionally, as Figure 4 shown, the power control signal writing scan line WS1 and the analog image signal writing scan line WS2 are provided from the scanning unit 20 as writing scan lines WS for each row of pixels. The power control signal writing scan line WS1 and the analog image signal writing scan line WS2 extend in the row direction.

[0078] The power control signal writing scan line WS1 supplies a first scan signal according to the power control signal, and this first scan signal is a digital signal that selects, in the row direction, pixel circuits 14 ( Figure 1 of the lighting control unit 50 + light emitting element 11) in which desired voltage values are respectively written. A reference triangular wave signal is supplied to the selected pixel circuits 14, and the light emitting elements 11 of the respective pixel circuits 14 emit light during the on period based on the voltage of the written analog image signal. When the analog image signal writing scan line WS2 passes the analog image signal writing voltage value, the drive current value for the light emitting element 11 that supplies the digital signal (i.e., the second scan signal) for selecting the pixel circuits 14 in the row direction is set according to the power control signal voltage (for details, refer to and incorporate by reference U.S. Patent No. 10885834).

[0079] (Drive unit 30)

[0080] As Figure 4 shown, for each column of pixels, the drive unit 30 extends the power control signal line SL1 and the analog image signal line SL2 vertically as signal lines SL. The drive unit 30 supplies a power control signal to each pixel circuit 14 via the power control signal line SL1. The power control signal is an analog signal that can obtain multiple voltage values. The drive unit 30 supplies an analog image signal to each pixel circuit 14 via the analog image signal line SL2. The analog image signal is also an analog signal that can obtain multiple voltage values. Each pixel circuit 14 to which the power control signal is supplied and a voltage value is written sets a drive current based on the written voltage value. Each pixel circuit 14 to which the analog image signal is supplied and a voltage value is written sets a threshold voltage for comparison with the reference triangular wave signal based on the voltage value of the analog image signal, and sets the time width during which the pixel circuit 14 emits light (for details, refer to and incorporate by reference U.S. Patent No. 10885834).

[0081] In addition, the driving unit 30 can also generate a reference triangular wave signal supplied to each pixel circuit 14 column by column. Alternatively, this reference triangular wave signal can also be separately provided as a reference triangular wave circuit in a row lower than the lowermost row of the matrix of the pixel circuit 14. The driving unit 30 or the reference triangular wave circuit distributes, for example, the reference triangular wave supplied from the outside of these circuits to each column of the pixel circuits 14.

[0082] The driving unit 30 can also include a storage unit. In the storage unit, it is possible to store the brightness settings for multiple voltage values taken for the power control signal and the brightness settings for multiple voltage values taken for the analog image signal. The relationship between these voltage values and the brightness settings can be adjusted and set by visually confirming the brightness of the light-emitting elements 11 constituting the pixel circuit 14, etc. By appropriately setting the relationship between the voltage values and the brightness settings, gamma correction can be performed. One of the advantages of this method is that in the digital PWM method, the gray-scale characteristics are linear, whereas gamma correction can be applied to the signal. The storage unit is formed, for example, by an electrically rewritable storage circuit or the like.

[0083] (Drive control unit 60)

[0084] Furthermore, the drive control unit 60 controls the operations of these scanning units 20 and driving unit 30. In addition, the scanning unit 20 and the driving unit 30 control the lighting control units 50 of each pixel. As Figure 3 shown, each lighting control unit 50 can include a first control circuit 51 and a second control circuit 52. The first control circuit 51 supplies drive current to the first light-emitting element 11A and the second light-emitting element 11B, respectively. In addition, the second control circuit 52 controls the light-emitting periods of the first light-emitting element 11A and the second light-emitting element 11B, respectively. Sometimes, a structure in which a light-emitting element is connected to the lighting control unit 50 is also referred to as "pixel circuit 14". The first control circuit 51 is connected between the power supply line 9 and the second control circuit 52.

[0085] In addition, the pixel circuit 14 can be provided for each sub-pixel constituting one pixel 12. In the Figure 1 example, the pixel circuit 14 includes a first sub-pixel circuit 14A and a second sub-pixel circuit 14B. The first sub-pixel circuit 14A drives the first light-emitting element 11A constituting the first sub-pixel. On the other hand, the second sub-pixel circuit 14B drives the second light-emitting element 11B constituting the second sub-pixel. In the Figure 1 example, as the first sub-pixel, the first light-emitting element 11A emits blue light, and as the second sub-pixel, the second light-emitting element 11B emits green to red light, and one pixel 12 is constituted by these first sub-pixel and second sub-pixel.

[0086] (Information holding unit 70)

[0087] As described above, the second light-emitting element 11B is a multi-color light-emitting type light-emitting wavelength variable LED, and its second emission color changes according to the drive current. Therefore, it is necessary to determine the drive current value for driving the second light-emitting element 11B according to the second emission color in which the second light-emitting element 11B is desired to emit light. Accordingly, the current-chromaticity information indicating the correspondence between the emission color in which the second light-emitting element 11B emits light and the current value for emitting light of that color is stored in the information storage unit 70. The lighting control unit 50 refers to the information storage unit 70 and determines the drive current of the second light-emitting element 11B corresponding to the second emission color. The information storage unit 70 can include a storage element such as a current-chromaticity data memory for storing, for example, the current-chromaticity data of the second light-emitting element 11B.

[0088] In addition, in addition to storing the current-chromaticity information based on the measured values of the respective second light-emitting elements 11B arranged in the display unit 10, the information storage unit 70 may store the current-chromaticity information generated by measuring the drive current and emission color of a light-emitting element equivalent to each of the second light-emitting elements 11B arranged in the display unit 10. Alternatively, the information storage unit 70 may statistically determine the relationship between the drive current and the emission color of the second light-emitting element 11B and store the recorded current-chromaticity information. In Figure 1 the example, the information storage unit 70 has a table of emission chromaticity-drive current characteristics of (G-R) and a table of emission chromaticity-drive current-luminance characteristics of (G-R).

[0089] The drive control unit 60 controls the drive unit 30 to supply drive currents to the respective first light-emitting elements 11A and second light-emitting elements 11B so that the first light-emitting elements 11A and second light-emitting elements 11B emit light with the specified emission colors and emission luminances, respectively. Regarding the first light-emitting element 11A, since its first emission color is fixed, the drive control unit 60 is controlled so as to have a drive current corresponding to the emission luminance. On the other hand, regarding the second light-emitting element 11B, the drive control unit 60 determines the drive current value for driving each second light-emitting element 11B and the on-period for causing each second light-emitting element 11B to emit light, referring to the current-chromaticity information stored in the information storage unit 70, based on the specified emission color and gradation information for each of the second light-emitting elements 11B, and lights up and drives each second light-emitting element 11B with the drive current from the drive unit 30.

[0090] In addition, the drive control unit 60 performs gray-scale control of the emission luminance. For example, according to the specified emission color of each of the first light-emitting elements 11A and the second light-emitting elements 11B, with reference to the current-chromaticity information, the drive current values of the first light-emitting elements 11A and the second light-emitting elements 11B are determined, and according to the determined drive current values and the specified gray-scale information of each of the first light-emitting elements 11A and the second light-emitting elements 11B, the on-periods of the first light-emitting elements 11A and the second light-emitting elements 11B are determined.

[0091] The drive control unit 60 may also include a storage unit. In the storage unit, it is possible to store the luminance settings for a plurality of voltage values taken for the power control signal and the luminance settings for a plurality of voltage values taken for the analog image signal. The relationship between these voltage values and the luminance settings can be adjusted and set by visually confirming the luminance of the light-emitting elements constituting the pixel circuit 14, etc. By appropriately setting the relationship between the voltage values and the luminance settings, gamma correction can be performed. One of the advantages of this method is that in the digital PWM method, the gray-scale characteristics are linear, whereas gamma correction can be applied to the signal. The storage unit is formed, for example, by an electrically rewritable storage circuit or the like.

[0092] In addition, the drive control unit 60 may perform lighting control of the first light-emitting elements 11A and the second light-emitting elements 11B simultaneously by the drive unit 30 in a state where the on-period information for one frame amount of the first light-emitting elements 11A and the second light-emitting elements 11B constituting the display unit 10 is written in the storage unit.

[0093] The drive control unit 60 determines the drive current value for driving each of the first light-emitting elements 11A and the light-emitting period for each of the first light-emitting elements 11A to emit light according to the emission color and gray-scale information of each of the first light-emitting elements 11A and the second light-emitting elements 11B provided from the outside. In addition, with reference to the current-chromaticity information held by the information holding unit 70, the drive current value for driving each of the second light-emitting elements 11B and the light-emitting period for each of the second light-emitting elements 11B to emit light are determined. Then, the drive control unit 60 performs lighting drive of each of the first light-emitting elements 11A and the second light-emitting elements 11B through the drive unit 30. With such a configuration, lighting control of the display unit 10 constituted by the first light-emitting elements 11A having a fixed wavelength and the multi-color light-emitting second light-emitting elements 11B can be achieved.

[0094] Regarding the second emission color of the second light-emitting element 11B, if the drive current values for emitting light of each emission color, red (R), green (G), and blue (B), are respectively set as IR, IG, and IB, the magnitudes of the drive current values are IR < IG < IB. Therefore, if the light-emitting periods of the maximum gray-scale of each color are set as TR, TG, and TB, the relationship of the lengths of the maximum light-emitting periods of each color during white display corresponding to full lighting is TR > TG > TB.

[0095] However, when the second emission color is variable over the entire range of R, G, and B, the range of variation of the drive current of the second light-emitting element 11B becomes large, and its control becomes complicated. Therefore, by making the first emission color different from the second emission color and having the first light-emitting element 11A assume the first emission color, the range of the second emission color assumed by the second light-emitting element 11B can be restricted, simplifying the control. As the assignment of the first emission color and the second emission color, it is preferable to make the first emission color blue and the second emission color change from green to red, or make the second emission color change from blue to green and make the first emission color red in such a way that the second emission color changes continuously. Among the drive current values of the multi-color light-emitting type LED, the drive current value (IB) for blue emission is the largest. Therefore, by making the first emission color blue and the second emission color green to red, the drive current value of the second light-emitting element 11B can be suppressed, which is more preferable.

[0096] In addition, by the above-described assignment of emission colors, the problem of color breakup that occurs during field-sequential driving in which the emission color is changed for each sub-frame can also be solved. That is, by making the first light-emitting element 11A emit blue light and the second light-emitting element 11B emit green to red light, the emissions of the first light-emitting element 11A and the second light-emitting element 11B can be divided into a B sub-frame and a GR sub-frame that varies in (G-R) and driven. Here, since the resolution of the human eye is low for blue light, even if the blue light is assigned to other sub-frames and field-sequential driving is performed, it is difficult to recognize color breakup. As a result, the occurrence of color breakup can be avoided, and while using a multi-color light-emitting type LED, the useless non-light-emitting period can be reduced, and sufficient emission luminance can be obtained.

[0097] Therefore, in the light-emitting device 100 of Embodiment 1, the first light-emitting element 11A emits blue light of the first emission color, and the second light-emitting element 11B emits light of any color from red to green (RG) as the second emission color. Thereby, no color breakup occurs, and full-color emission can be achieved by the first light-emitting element 11A and the second light-emitting element 11B. PWM can be used for gray-scale control of each emission color. Here, the product of the maximum light-emitting period based on PWM driving and the drive current value is R > G > B. This is because the light-emitting luminance efficiency of the second light-emitting element 11B increases in the order of R < G < B.

[0098] In addition, in the above description, it has been assumed that the second emission color of the second light-emitting element 11B can be varied over the entire range of R, G, and B. However, by manufacturing the second light-emitting element 11B in such a way that the second emission color is variable only in the range from R to G, advantages such as simplification of the manufacturing process and cost reduction can be obtained. For example, the manufacturing process margin of the second light-emitting element 11B can be further expanded.

[0099] (Timing diagram)

[0100] Figure 2 Shows a Figure 1 timing diagram showing the lighting timings of the respective RGB colors of the light-emitting device 100. Here, one frame period FT is divided into a first sub-frame period SF1 in which the first light-emitting element 11A emits light and a second sub-frame period SF2 in which the second light-emitting element 11B emits light. The first sub-frame period SF1 becomes a B sub-frame that emits blue light, and the second sub-frame period SF2 becomes a GR sub-frame that emits any one color light from green light to red light. In the B sub-frame, a current value corresponding to blue light, for example, 470 nm, is supplied to the first light-emitting element 11A. In addition, in the GR sub-frame, since the light can be changed from green light to red light, the second light-emitting element 11B is supplied with current in the range from a current value corresponding to green light, for example, 515 nm, to a current value corresponding to red light, for example, 630 nm. That is, in the B sub-frame, the maximum current value that causes the first light-emitting element 11A to emit light is supplied, and in the GR sub-frame, the drive current corresponding to the second emission color is supplied. In other words, in the GR sub-frame, the Figure 2 vertical axis (drive current) is used to control the emission color.

[0101] In addition, in each sub-frame, the emission brightness is controlled by PWM control. By changing the ON period ONT within the maximum emission period LTmax, the current value can be supplied at the maximum value, and the cumulative current value can be changed to adjust the brightness to the desired value. Here, the maximum emission period of blue light is set as LTmaxB, and the ON period is set as ONTB. On the other hand, within the maximum emission period from green light to red light, the maximum emission period of green light is set as LTmaxG, and the maximum emission period of red light is set as LTmaxR. In addition, the ON period ONT is included within the maximum emission period. Actually, as shown by the slashes in Figure 2 , the drive current value (vertical axis) is determined according to the required emission color, and the horizontal axis is determined according to the brightness. In this way, together with the B sub-frame and the (G-R) sub-frame, the brightness is controlled on the Figure 2 horizontal axis (ON period) of

[0102] In addition, a pixel signal writing period is set in each sub-frame, and PWM control is performed after the pixel signal writing period. During the pixel signal writing period, pixel signals for one frame amount of the first light-emitting element 11A and the second light-emitting element 11B are written into the pixel memory. The driving unit 30 refers to the pixel signals written in the pixel memory and controls the lighting of the light-emitting element 11. The pixel memory is provided in the lighting control unit 50 of the pixel circuit 14.

[0103] As Figure 3 shown, the lighting control unit 50 includes a first control circuit 51 and a second control circuit 52. The first control circuit 51 performs current driving according to the emission color. In addition, the second control circuit 52 performs PWM control. Specifically, when performing PWM control, the second control circuit 52 sets the time width of the current supplied to the light-emitting element 11 based on the result of comparing a first signal including a triangular wave signal and a first DC voltage set during a specified period. In addition, the first control circuit 51 controls the current value supplied to the lighting control unit 50 based on a second DC voltage set during a period different from the specified period.

[0104] In addition, as Figure 4 shown, the power control signal writing scan line WS1 and the analog image signal writing scan line WS2 extend from the scanning unit 20 and are connected to each pixel 12. In addition, the power control signal line SL1 and the analog image signal line SL2 extend from the driving unit 30 and are connected to each pixel 12. The driving unit 30 is a driver IC that processes the power control signal and the analog image signal. The power control signal writing scan line WS1 and the analog image signal writing scan line WS2 are connected to the TFT circuit provided on the mounting substrate together with the pixel circuit 14. The TFT is made of low-temperature polysilicon or oxide semiconductor.

[0105] As Figure 4As shown in the enlarged view of the main part, each pixel 12 is composed of a plurality of sub-pixels. Here, the pixel 12 is composed of a first sub-pixel 12A and a second sub-pixel 12B. Each sub-pixel is composed of a light-emitting element 11. Specifically, the first sub-pixel 12A includes a first lighting control unit 50A and a first light-emitting element 11A that constitutes the first sub-pixel 12A. In addition, the second sub-pixel 12B includes a second light source control unit 50B and a second light-emitting element 11B that constitutes the second sub-pixel 12B. Each pixel circuit 14 includes a lighting control unit 50. Here, the first lighting control unit 50A includes a first control circuit 51A and a second control circuit 52A. In addition, the second lighting control unit 50B includes a first control circuit 51B and a second control circuit 52B. The first control circuits 51A and 51B supply drive currents to the first light-emitting element 11A and the second light-emitting element 11B, respectively. On the other hand, the second control circuits 52A and 52B control the light-emitting periods of the first light-emitting element 11A and the second light-emitting element 11B, respectively. Here, the first control circuits 51A and 51B are composed of power supply control circuits, and the second control circuits 52A and 52B are composed of analog image PWM circuits. The first control circuits (power supply control circuits) 51A and 51B are connected to the power line 9 and the power supply control signal line SL1. In addition, a power supply control signal writing timing is input from the power supply control signal writing scan line WS1. On the other hand, the second control circuits (analog image PWM circuits) 52A and 52B are connected in series with the power line 9 via the first control circuits 51A and 51B, respectively. In addition, the second control circuits 52A and 52B are also connected to the analog image signal line SL2. In addition, an analog image signal writing timing is input from the analog image signal writing scan line WS2. In this way, the light-emitting element 11 is connected to the power line 9 via the power supply control circuit and the analog image PWM circuit, respectively. Moreover, the drive current value is controlled by the power supply control circuit, and the drive time is controlled by the analog image PWM circuit.

[0106] In addition, in Figure 4 the example, an example in which the first sub-pixel 12A and the second sub-pixel 12B are each composed of one LED is shown, but the present disclosure is not limited to this structure, and each sub-pixel may be composed of a plurality of light-emitting elements such as LEDs. For example, in the case of using a plurality of light-emitting elements for the purpose of increasing brightness or the like, two or more light-emitting elements may be connected in series.

[0107] (LED)

[0108] Figure 5This shows an example of the component structure when an LED is used as the light-emitting element 11. The light-emitting element 11 shown in this figure includes an n-type semiconductor layer 2, an active layer 3, a p-type semiconductor layer 4, an n-side electrode 5, and a p-side electrode 6. The active layer 3 can utilize a multi-quantum well structure (MQW) or the like. The light-emitting element 11 is connected to a pixel drive circuit 8 such as a DC power supply, and receives a drive current supply from a power line 9 to emit light. The first light-emitting element 11A controls the light-emitting period under a specified drive current. The emission color of the first light-emitting element 11A is fixed to blue. In addition, the second light-emitting element 11B controls the second emission color through the drive current, and controls the light-emitting period under this drive current. The second emission color can be changed to any color from green light to red light.

[0109] (B sub-frame)

[0110] Figure 6 This shows the lit image in the B sub-frame of such a display unit 10 being used, Figure 7 This shows the lit image in the GR sub-frame. In these figures, each pixel 12 is represented as a brick shape. In the B sub-frame, the brightness is different between the pixels 12, but the chromaticity is constant. The brightness gray scale is controlled by PWM. Figure 6 The difference in the concentration of each pixel 12 of represents the difference in the average brightness within the sub-frame.

[0111] (GR sub-frame)

[0112] On the other hand, in the GR sub-frame, both the brightness and the chromaticity are variable between the pixels 12. In the (G - R) sub-frame, the current value supplied to the second light-emitting element 11B and the second emission color, that is, the chromaticity, are controlled within the range of (G - R). Specifically, in each pixel 12, the lighting control unit 50 obtains the chromaticity of RGB with reference to the information storage unit 70. Here, the chromaticity of B, that is, the first emission color emitted by the first light-emitting element 11A, is uniquely determined. On the other hand, it is necessary to determine the second emission color of the second light-emitting element 11B. Here, first, according to the chromaticity signal to be displayed, in a manner corresponding to the color when B emits light, the emission color when the (G - R) wavelength is variable and the brightness ratio of B:(G - R) are determined. Then, according to the chromaticity and the brightness ratio of the emission color, the emission intensity corresponding to the brightness signal to be displayed is determined.

[0113] (Drive method of the light-emitting device)

[0114] Here, an example of a driving method for a light-emitting device will be described. Here, a process will be described in which the lighting control unit 50 divides one frame in which a plurality of first light-emitting elements 11A and a plurality of second light-emitting elements 11B emit light into a first sub-frame and a second sub-frame and drives them. In the first sub-frame, the plurality of first light-emitting elements 11A emit light respectively. Here, since blue light is emitted as the first light-emitting color in the first sub-frame, it is called the B sub-frame. In addition, in the second sub-frame, the plurality of second light-emitting elements 11B emit light respectively. Here, since the second light-emitting color is emitted in the second sub-frame, it is called the RG sub-frame.

[0115] The lighting control unit 50 supplies drive currents to the first light-emitting elements 11A and the second light-emitting elements 11B through the first control circuit 51, and controls the light-emitting periods of the first light-emitting elements 11A and the second light-emitting elements 11B by the second control circuit 52. The process of the lighting control unit 50 driving the plurality of first light-emitting elements 11A and the plurality of second light-emitting elements 11B includes the following processes: determining the second light-emitting color and the brightness ratio between the first light-emitting elements 11A and the second light-emitting elements 11B in a manner corresponding to the first light-emitting color according to the chrominance signal and the luminance signal to be displayed by the pixel 12; determining the light-emitting intensity corresponding to the luminance signal to be displayed based on the chrominance and the brightness ratio of the second light-emitting color; the first control circuit 51 referring to the information holding unit 70 and supplying drive current values corresponding to their respective light-emitting colors to the first light-emitting elements 11A and the second light-emitting elements 11B; the second control circuit 52 controlling the light-emitting periods of the drive current values supplied to the first light-emitting elements 11A and the second light-emitting elements 11B according to the determined light-emitting intensity.

[0116] In addition, in the first sub-frame, the first control circuit 51 controls the driving current of the plurality of first light-emitting elements 11A to be constant, and the second control circuit 52 controls the light-emitting intensity by PWM control. The driving current of the first light-emitting element 11A is set to a driving current value with good efficiency for blue light emission. For example, it is set to the rated current value. On the other hand, in the second sub-frame, the first control circuit 51 controls the light-emitting color according to the current value for driving the plurality of second light-emitting elements 11B. In addition, the second control circuit 52 controls the brightness by controlling the light-emitting period of the current value of the plurality of second light-emitting elements 11B controlled by the first control circuit 51. Specifically, according to the chrominance signal and the luminance signal to be displayed by each pixel 12, the chrominance of the second light-emitting color and the luminance ratio between the first light-emitting element 11A and the second light-emitting element 11B are determined in a manner corresponding to the first light-emitting color. Then, based on the chrominance and the luminance ratio of the second light-emitting color, the light-emitting intensity corresponding to the luminance signal to be displayed by the second light-emitting element 11B is determined. Accordingly, the first control circuit 51 refers to the information holding unit 70 and supplies the driving current values corresponding to the respective light-emitting colors to the first light-emitting element 11A and the second light-emitting element 11B. In addition, the second control circuit 52 controls the light-emitting periods of the first light-emitting element 11A and the second light-emitting element 11B according to the determined light-emitting intensity.

[0117] (Method for determining driving current value and PWM light-emitting period)

[0118] Here, based on Figure 8 the functional block diagram of Figure 9 and the chromaticity diagram of

[0119] Next, in step S802, a predetermined light-emitting chrominance and luminance are determined for each pixel. Here, in Figure 9The point A on the chromaticity diagram represents an arbitrary emission chromaticity to be emitted. In this chromaticity diagram, the first light-emitting element 11A emits blue light as the first emission color, so it is fixed at point B near the lower left vertex of the chromaticity diagram. On the other hand, the second light-emitting element 11B emits the second emission color in any color between green light and red light. Therefore, if it is represented on the chromaticity diagram, it becomes any position between green near the upper vertex of the chromaticity diagram and red near the right vertex, point C. Therefore, the chromaticity of point A represented by the mixed light of the first light-emitting element 11A and the second light-emitting element 11B can be represented by point B and point C. In other words, in order to represent the chromaticity of point A, the emission color of the second light-emitting element 11B is adjusted in such a way as to adjust point C. Furthermore, considering the balance of the brightness of the first light-emitting element 11A and the second light-emitting element 11B, the brightness ratio of B:(G-R) is determined for a specified point A. Thus, the drive current value and the emission period of the second light-emitting element 11B at point C are determined.

[0120] Based on the above considerations, first, if the emission chromaticity (B) of B is considered according to the emission chromaticity (A) of A determined in step S802 (step S803), then the emission chromaticity (C) of (G-R) and the brightness ratio of B:(G-R) are determined (step S804). When determining the brightness ratio of B:(G-R) in step S804, based on the brightness of the emission chromaticity (A) in step S802, the brightness of (G-R) and the brightness of B are necessarily obtained (step S808).

[0121] On the other hand, when determining the emission chromaticity (C) of (G-R) in step S804, by referring to the emission chromaticity-drive current characteristic table of (G-R) held in the information holding unit 70 (step S805), the drive current value of (G-R) is determined (step S806).

[0122] Furthermore, when the drive current value of (G-R) is determined in step S806, referring to the emission chromaticity-drive current-brightness characteristic table of (G-R) held in the information holding unit 70 (step S807) and the brightness of (G-R) (step S808), the PWM emission period of (G-R) is determined (step S809).

[0123] On the other hand, based on the brightness of B obtained in step S808, referring to the brightness characteristic value of the drive current value corresponding to the chromaticity of B (step S810), the PWM emission period of B is determined (step S811). In this way, the respective drive current values of the second light-emitting element 11B and the PWM emission periods of the first light-emitting element 11A and the second light-emitting element 11B are determined. In addition, as shown above Figure 2 The drive current value of the first light-emitting element 11A is the drive at the maximum value of the drive current value that causes the first light-emitting element 11A to emit light.

[0124] In the light-emitting device 100 of the above-described Embodiment 1, a first light-emitting element 11A and a second light-emitting element 11B are provided for each pixel 12. And, as Figure 10A shown, the first light-emitting element 11A is a fixed-wavelength light-emitting element that emits blue light, and the second light-emitting element 11B is a variable-wavelength light-emitting element that emits light from green to red. In this example, one first light-emitting element 11A and one second light-emitting element 11B are provided in each pixel 12, but multiple first light-emitting elements and / or second light-emitting elements can also be provided for each pixel. Thereby, the light-emitting luminance can be increased.

[0125] In addition, in Embodiment 1, one frame period FT is divided into a first sub-frame period SF1 in which the first light-emitting element 11A emits light and a second sub-frame period SF2 in which the second light-emitting element 11B emits light. The first sub-frame period SF1 is set as a B sub-frame that emits blue light, and the second sub-frame period SF2 is set as a GR sub-frame that emits any one color light from green to red. Figure 2 illustrates a case where the first sub-frame period SF1 is before the second sub-frame period SF2. However, the present disclosure is not limited to this structure. For example, the second sub-frame, which is a GR sub-frame that emits any one color light from green to red, can also precede the first sub-frame, which is a B sub-frame that emits blue light. As described above, the human visual sensitivity perceives luminance in the GR sub-frame and synthesizes the GR sub-frame and the B sub-frame to perceive color, but the time resolution is the timing for perceiving luminance. Therefore, by making the GR sub-frame precede, an effect of suppressing the delay of the human perception timing with respect to the video display data input to the display system can be obtained. In addition, in this case, the preceding GR sub-frame can also be renamed as the first sub-frame, and the B sub-frame can be renamed as the second sub-frame.

[0126] [Embodiment 2]

[0127] In addition, the present disclosure is not limited to a structure in which the first light-emitting element is a fixed wavelength and the second light-emitting element is a variable wavelength. The first light-emitting element can also be a variable-wavelength light-emitting element. An example of such a light-emitting device 200 of Embodiment 2 is shown in Figure 10B . In addition, in Figure 10A , Figure 10BIn the example shown, the light-emitting element of the fixed wavelength type is represented by a quadrilateral, and the light-emitting element of the variable wavelength type is represented by a quadrilateral with diagonal lines. In addition, regarding the light-emitting element of the variable wavelength type, it is driven such that the emission wavelength is variable within the range from the emission color in the upper left region divided by the diagonal lines of the quadrilateral to the emission color in the lower right region. Here, dividing the quadrilateral with diagonal lines is merely an intention to represent the change in the emission wavelength, and it does not mean physically dividing the light-emitting region of the light-emitting element with diagonal lines to emit light of different emission colors for each region.

[0128] In Figure 10A the light-emitting device of Embodiment 1 shown, it is shown that the first light-emitting element 11A is of the fixed wavelength type and the second light-emitting element 11B is of the variable wavelength type, and the emission wavelength is variable within the range of emission colors from red R to green B for use. In contrast, in Figure 10B Embodiment 2 shown, the first light-emitting element 11A' also uses a light-emitting element of the variable wavelength type, and its emission wavelength is shown to be fixed to blue B and driven.

[0129] In addition, regardless of the actually driven emission wavelength range, the variable range of the emission wavelength of the light-emitting element of the variable wavelength type for the first light-emitting element 11A' can be B-G, and even if it is B-R or B-Y, as long as B is included in the variable range of the emission wavelength. In addition, at this time, regardless of the actually driven emission wavelength range, if the variable ranges of the emission wavelengths of the light-emitting elements of the variable wavelength type used for the first light-emitting element 11A' and the second light-emitting element 11B are both variable in B-R, each pixel 12D can be configured using a single specification of light-emitting element, and thus the advantage of being able to simplify the manufacturing process of the pixel 12D can be obtained.

[0130] In addition, in order to fix the first light-emitting element 11A' of the variable wavelength type to the first emission color of blue light and make it emit light, the information holding unit 70 holds not only the second light-emitting element 11B but also the current-chromaticity information of the first light-emitting element 11A'. The lighting control unit 50 refers to the information holding unit 70 and determines the drive current of the first light-emitting element 11A' corresponding to the first emission color. Furthermore, by making the first light-emitting element 11A' of the variable wavelength type, the wavelength of the blue light can also be adjusted. For example, the deviation of the emission wavelength of the first light-emitting element 11A' can be corrected between the pixels 12D to make the wavelengths of the blue light of each pixel 12D consistent.

[0131] In addition, in the above example, the active matrix driving method has been described, but the present disclosure can also be applied to the passive matrix driving method.

[0132] Industrial Applicability

[0133] The light-emitting device of the present disclosure can be suitably used for, for example, medium-sized and large-sized displays, indicators, signs, and the like.

Claims

1. A light emitting device comprising: A display unit, wherein a plurality of first light emitting elements capable of emitting a first light emitting color and a plurality of second light emitting elements capable of emitting a second light emitting color different from the first light emitting color are arranged in a predetermined pattern to form a plurality of pixels; a lighting control unit that supplies driving current to each of the plurality of first light emitting elements and the plurality of second light emitting elements to control a light emitting period; The second light emitting element can control the light emission color according to the driving current, The lighting control unit drives the plurality of first light emitting elements and the plurality of second light emitting elements so as to divide one frame in which the plurality of first light emitting elements emit light into a first subframe in which the plurality of first light emitting elements emit light and a second subframe in which the plurality of second light emitting elements emit light.

2. The light emitting device according to claim 1, wherein: further comprising an information storage unit that stores current-chromaticity information for determining a driving current value for causing the first light emitting element and the second light emitting element to emit light according to a predetermined light emission color of the plurality of pixels, The lighting control unit controls the plurality of first light emitting elements and the plurality of second light emitting elements so that the plurality of first light emitting elements and the plurality of second light emitting elements emit light at a predetermined light color and light brightness, respectively, based on the current-chromaticity information held by the information holding unit.

3. The light emitting device according to claim 1 or 2, wherein: The lighting control unit includes: a first control circuit that supplies a driving current to the first light emitting element and the second light emitting element; and a second control circuit that controls a light emitting period of the first light emitting element and the second light emitting element.

4. The light emitting device according to any one of claims 1 to 3, wherein: At least one lighting control unit is provided for each of the pixels.

5. The light emitting device according to any one of claims 1 to 4, wherein: Each of the pixels includes at least one of the first light-emitting elements and at least one of the second light-emitting elements.

6. The light emitting device according to any one of claims 1 to 5, wherein: The first luminescent color is blue light.

7. The light emitting device according to any one of claims 1 to 6, wherein: The first light emission color is fixed wavelength light emission.

8. The light emitting device according to any one of claims 1 to 7, wherein: The second luminescent color is variable between green light and red light according to a driving current.

9. The light emitting device according to any one of claims 1 to 8, wherein: In the second subframe, the chromaticity of the second luminous color and the brightness ratio of the first luminous element to the second luminous element are determined in a manner corresponding to the first luminous color based on a chromaticity signal and a brightness signal respectively indicating the chromaticity and brightness to be displayed by each pixel, determining, based on the chromaticity of the second luminescent color and the luminance ratio, a luminous intensity corresponding to a luminance signal indicating luminance to be displayed by the second luminescent element, The first control circuit refers to the information storage unit to supply the first light emitting element and the second light emitting element with driving current values ​​corresponding to the respective emission colors. The second control circuit controls the light emission periods of the first light emitting element and the second light emitting element according to the determined light emission intensity.

10. The light emitting device according to any one of claims 1 to 9, wherein: The lighting control unit is configured to set a time width for supplying current to the first light emitting element and the second light emitting element based on a result of comparing a first signal including a triangular wave signal with a first DC voltage set in a predetermined period, A current value supplied to the lighting control unit is controlled based on a second DC voltage set in a period different from the predetermined period.

11. A method for driving a light emitting device, the light emitting device comprising: A display unit, wherein a plurality of first light emitting elements capable of emitting a first light emitting color and a plurality of second light emitting elements capable of emitting a second light emitting color different from the first light emitting color and capable of controlling the light emitting color according to a driving current are arranged in a predetermined pattern to form a plurality of pixels; a lighting control unit that supplies driving current to each of the plurality of first light emitting elements and the plurality of second light emitting elements to control a light emitting period; The driving method of the light emitting device comprises the following steps: The lighting control unit drives the plurality of first light emitting elements and the plurality of second light emitting elements so as to divide one frame in which the plurality of first light emitting elements emit light into a first subframe in which the plurality of first light emitting elements emit light and a second subframe in which the plurality of second light emitting elements emit light.

12. The driving method of the light emitting device according to claim 11, wherein: The step of the lighting control unit driving the plurality of first light emitting elements and the plurality of second light emitting elements includes the following steps: determining the second luminous color and the brightness ratio between the first luminous element and the second luminous element in a manner corresponding to the first luminous color based on a chromaticity signal and a brightness signal indicating chromaticity and brightness to be displayed by the pixel; determining, based on the chromaticity of the second luminescent color and the luminance ratio, a luminescent intensity corresponding to a luminance signal indicating luminance to be displayed; The first control circuit of the lighting control unit supplies the first light emitting element and the second light emitting element with driving current values ​​corresponding to the respective emission colors with reference to the information holding unit holding current-chromaticity information, wherein the current-chromaticity information is used to determine the driving current values ​​for causing the first light emitting element and the second light emitting element to emit light according to the prescribed emission colors of the plurality of pixels; The second control circuit of the lighting control unit controls a light emission period of the driving current value supplied to the first light emitting element and the second light emitting element based on the determined light emission intensity.

13. The driving method of the light emitting device according to claim 11 or 12, wherein: The step of the lighting control unit driving the plurality of first light emitting elements and the plurality of second light emitting elements includes: In the first subframe, the first control circuit controls the light emission intensity by PWM control while keeping the driving current of the plurality of first light emitting elements constant. In the second subframe, the first control circuit controls the light emission color according to the current value of driving the plurality of second light emitting elements; In the second subframe, the second control circuit controls the brightness according to the light emission period of the current value of the plurality of second light emitting elements controlled by the first control circuit.

Images