Control device and display device

Abstract

A display device includes a backlight having a light emitting region including light emitting elements, and a control device. The light emitting elements include first light emitting components that emit first light, second light emitting components that emit second light having a peak wavelength shorter than the first light, and third light emitting components that emit third light having a peak wavelength shorter than the second light. The first and second light emitting components are fluorescent components that receive the third light to emit the first and second light as fluorescent light, respectively. The control device generates pixel data for sub-pixels that display the first light using a first time constant, generates pixel data for sub-pixels that display the second light using a second time constant different from the first time constant, and generates pixel data for sub-pixels that display the third light using a third time constant different from the first time constant.

Description

TECHNICAL FIELD

[0001] The following disclosure relates to a control device that controls a display device having a plurality of light emitting components that respectively emit different colors. BACKGROUND

[0002] In recent years, various studies have been made on display devices that use a plurality of light emitting components (light emitting materials) that respectively emit different colors to achieve color display. For example, a technique for coping with a decrease in display quality of a display device caused by a difference in afterglow characteristics of the respective light emitting materials is disclosed in Patent Document 1. Specifically, in the technique of Patent Document 1, a pseudo afterglow signal is added to an image signal corresponding to a light emitting material with a short afterglow time.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Laid-Open No. 2005-141204 SUMMARY

[0006] Technical Problem to be Solved by the Invention

[0007] However, as described later, there is room for improvement in the specific method for improving the display quality of a display device. An object of one aspect of the present disclosure is to improve the display quality of a display device having a plurality of light emitting components that respectively emit different colors by a method different from the past.

[0008] Technical Solution to Solve the Technical Problem

[0009] To solve the above problems, one embodiment of the present disclosure relates to a control device that controls a display device, the display device including: a display panel that has a display region in which a plurality of display pixels are arranged, and that displays an image based on an image signal; and a backlight that has at least one light emitting region that irradiates the plurality of display pixels based on the image signal, the at least one light emitting region including at least one light emitting element as a light source, each of the plurality of display pixels including: (i) a first display subpixel that displays a first color; (ii) a second display subpixel that displays a second color different from the first color; and (iii) a third display subpixel that displays a third color different from the first color and the second color, each of the at least one light emitting element including: a first light emitting part that emits first light of the first color; a second light emitting part that emits second light of the second color and having a shorter peak wavelength than the first light; and a third light emitting part that emits third light of the third color and having a shorter peak wavelength than the second light, the third light emitting part being an excitation light source that emits the third light as excitation light, the first light emitting part being a first phosphor part that receives the third light and emits the first light as fluorescent light, the second light emitting part being a second phosphor part that receives the third light and emits the second light as fluorescent light, each of the at least one light emitting element emitting mixed light of the first light, the second light, and the third light as mixed light to the plurality of display pixels, the control device including: a backlight luminance calculation part that generates backlight luminance data based on the image signal; and a display pixel data generation part that generates display pixel data based on the backlight luminance data and the image signal, the display pixel data including: (i) first display subpixel data corresponding to the first display subpixel; (ii) second display subpixel data corresponding to the second display subpixel; and (iii) third display subpixel data corresponding to the third display subpixel, the display pixel data generation part generating the first display subpixel data using a first time constant, generating the second display subpixel data using a second time constant different from the first time constant, and generating the third display subpixel data using a third time constant different from the first time constant.

[0010] Advantageous Effects

[0011] According to one embodiment of the present disclosure, display quality of a display device including a plurality of light emitting parts that emit respective different colors can be improved by a method different from the related art. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1is a block diagram showing a configuration of a main part of a display device according to Embodiment 1.

[0013] Figure 2 is a diagram showing a schematic configuration of a light emitting element in Embodiment 1.

[0014] Figure 3 is a diagram showing a correspondence relationship between a light emitting region of a BL of Embodiment 1 and a light emitting element.

[0015] Figure 4 is a diagram for explaining a luminance distribution of a light emitting element.

[0016] Figure 5 is a diagram showing a configuration example of a BL luminance distribution color filter operation section in Embodiment 1.

[0017] Figure 6 is a diagram showing an example of f(R) and f(G, B).

[0018] Figure 7 is a diagram explaining a relationship between a BL luminance, a panel transmittance, and a display image luminance in an ideal display device.

[0019] Figure 8 is a diagram explaining a relationship between a BL luminance, a panel transmittance, and a display image luminance in Comparative Example 1.

[0020] Figure 9 is a diagram explaining a relationship between a BL luminance, a panel transmittance, and a display image luminance in Comparative Example 2.

[0021] Figure 10 is a diagram explaining a relationship between a BL luminance, a panel transmittance, and a display image luminance in Embodiment 1.

[0022] Figure 11 is a block diagram showing a configuration of a main part of a display device according to a modification of Embodiment 1.

[0023] Figure 12 is a diagram showing a configuration example of a BL luminance distribution color filter operation section in a display device of Embodiment 2.

[0024] Figure 13 is a diagram showing an example of a correction table in Embodiment 2.

[0025] Figure 14 is a diagram explaining a relationship between a BL luminance, a panel transmittance, and a display image luminance in a reference example.

[0026] Figure 15 is a diagram explaining a relationship between a BL luminance, a panel transmittance, and a display image luminance in Embodiment 2.

[0027] Figure 16 is a block diagram showing a configuration of a main part of a display device according to Embodiment 3. DETAILED DESCRIPTION

[0028] (Embodiment 1)

[0029] Hereinafter, the display device 1 according to Embodiment 1 will be described. For the convenience of explanation, in the following embodiments, the same reference numerals are assigned to components having the same function as those described in Embodiment 1, and the description thereof will not be repeated. In addition, for the sake of simplicity, the description of matters common to the known art will also be appropriately omitted.

[0030] Note that each configuration and each numerical value described in this specification is only an example unless specifically indicated. Therefore, the positional relationship of each component is not limited to the example of each drawing unless specifically indicated. In addition, it should be noted that each drawing schematically illustrates the shape, structure, and positional relationship of each component, and is not necessarily drawn to scale. In this specification, the expression "A and B" includes only A, only B, and both A and B unless specifically indicated. Such a description means "A or less and B or more" unless specifically indicated.

[0031] In this specification, the following abbreviations are used:

[0032] • BackLight: "BL"

[0033] • Local Dimming: "LD"

[0034] • ColorFilter: "CF"

[0035] • Electro-Luminescence: "EL"

[0036] • Photo-Luminescence: "PL".

[0037] In addition, "afterglow characteristics of a light-emitting material" described in this specification collectively indicates "a delay characteristic of a decrease in light intensity emitted from a light-emitting material" and "a delay characteristic of an increase in light intensity emitted from a light-emitting material". Therefore, in this specification, "afterglow time" collectively indicates "a delay time of a decrease in light intensity" and "a delay time of an increase in light intensity".

[0038] (Outline of Display Device 1)

[0039] Figure 1is a block diagram showing a configuration of a main part of the display device 1. The display device 1 is provided with a control section 10 (control device), an image signal acquisition section 20, and a display section 30. The display device 1 displays an image based on an image signal in accordance with a prescribed video standard. As an example of the prescribed video standard, an HDR (High Dynamic Range) standard can be cited. The display device 1 can be a terminal device of a portable type, or can also be a device of a stationary type.

[0040] The control section 10 controls each section of the display device 1 as a whole. As described below, the control section in one embodiment of the present disclosure processes an image signal supplied by the image signal acquisition section 20. Therefore, the control device in one embodiment of the present disclosure can also be called an image processing device. The control section 10 is provided with a BL luminance calculation section 11, a BL luminance filter operation section 12, and a display pixel data generation section 13. The display pixel data generation section 13 has a BL luminance distribution calculation section 131, a BL luminance distribution filter operation section 132, and a transmittance decision section 133. Examples of the operation of each section of the control section 10 will be described later.

[0041] The image signal acquisition section 20 acquires an image signal. As an example, the image signal acquisition section 20 acquires an image signal by decoding a broadcast signal received by the display device 1. As another example, the image signal acquisition section 20 can also acquire an image signal from an external device not shown which is communicably connected to the display device 1. As an example of the external device, a BD (Blu-lay (registered trademark) Disc) player can be cited. The image signal acquisition section 20 supplies the acquired image signal to the control section 10. As a specific example, as shown in Fig. 1, the image signal acquisition section 20 supplies the image signal to the BL luminance calculation section 11 and the transmittance decision section 133.

[0042] The display section 30 is, for example, a liquid crystal display. The display section 30 is provided with a BL 31 and a display panel 35. The display panel 35 is an example of a display panel to which one embodiment of the present disclosure is directed. The display panel 35 has a plurality of display pixels 350 (example: liquid crystal pixels) whose light transmittance (hereinafter, simply referred to as transmittance) can be controlled. Specifically, the display panel 35 has I1 x J1 display pixels 350. I1 represents the number of display pixels per row, and J1 represents the number of display pixels per column. I1 and J1 are each an integer of two or more. In this way, the display pixels 350 are arranged in a two-dimensional matrix shape in a display region (region in which an image is displayed) of the display panel 35. The transmittance of the display pixels 350 is controlled in accordance with an image signal.

[0043] Display pixel 350 has a plurality of display subpixels for color display of an image. In Embodiment 1, display pixel 350 has: (i) a first display subpixel displaying a first color, (ii) a second display subpixel displaying a second color, and (iii) a third display subpixel displaying a third color. The first color to the third color are different colors. In Embodiment 1, the case where the first color is red, the second color is green, and the third color is blue is illustrated. However, of course, the first color to the third color are not limited to this example.

[0044] In Embodiment 1, the display pixel 350 includes: (i) a red display subpixel (displaying red) serving as a first display subpixel, (ii) a green display subpixel (displaying green) serving as a second display subpixel, and (iii) a blue display subpixel (displaying blue) serving as a third display subpixel. In the following description, the red display subpixel is abbreviated as RSUB, the green display subpixel as GSUB, and the blue display subpixel as BSUB.

[0045] BL31 illuminates display pixel 350. The BL31 in Embodiment 1 is an example of a BL with LD (Light Emitting Difference) function. Therefore, BL31 has multiple light-emitting areas 305 whose brightness can be independently controlled (see below). Figure 3 ).exist Figure 1 In this example, BL31 is positioned on the back of the display panel 35. However, BL31 only needs to illuminate the display pixels 350. Therefore, the configuration of BL31 is not limited to... Figure 1 Examples.

[0046] BL31 has I2 × J2 light-emitting regions 305. I2 represents the number of light-emitting regions in each row, and J2 represents the number of light-emitting regions in each column. In the example of Embodiment 1, both I2 and J2 are integers greater than 2. Thus, BL31 in Embodiment 1 is composed of multiple light-emitting regions 305 divided in two dimensions. Therefore, BL31 in Embodiment 1 can also be called a two-dimensional dimming type BL.

[0047] However, BL31 can also have multiple luminescent regions 305 that are divided in one dimension. That is, either I2 or J2 can be 1. For example, BL31 can also be divided into 1×J2 luminescent regions 305. Alternatively, BL31 can also be divided into I2×1 luminescent regions 305.

[0048] Thus, the light emission control method of this disclosure can also be applied to the light emission region 305, which is divided into one dimension. When either I2 or J2 is 1, BL31 can also be referred to as a one-dimensional dimming type BL. The one-dimensional dimming type BL and the two-dimensional dimming type BL can also be collectively referred to as LD type BL. In addition, it should be noted that, as described in Embodiment 3 below, the light emission control method of this disclosure can also be applied to non-LD type BLs.

[0049] In BL31, each of the plurality of light-emitting regions 305 contains at least one light-emitting element 310 as a light source. In Embodiment 1, for the sake of simplicity, the case where one light-emitting region 305 contains one light-emitting element 310 is illustrated. Therefore, BL31 in Embodiment 1 has 12 × J2 light-emitting elements 310. The brightness of the light-emitting region 305 (more specifically, the brightness of the light-emitting element 310) is controlled according to the image signal.

[0050] There is no particular limitation on the type of light-emitting element 310. In Embodiment 1, a white LED (Light Emitting Diode) is shown as an example. More specifically, in Embodiment 1, a QLED (Quantum Dot LED) is shown as an example.

[0051] (Example of the structure of light-emitting element 310)

[0052] Figure 2 This is a diagram showing a schematic configuration of the light-emitting element 310. In this specification, from... Figure 2 The direction from the second electrode 322 to the first electrode 327 is referred to as upward. Furthermore, the opposite direction is referred to as downward. In the following description, the vertical direction will also be referred to as the z-direction. The z-direction can also represent the normal direction of the display surface of the display panel 35. Figure 2 In the example, the positive direction of the z-direction is upward.

[0053] like Figure 2 As shown, the light-emitting element 310 includes an excitation light source 320, a phosphor component 330 (wavelength conversion component), and a CF component 340. The excitation light source 320, moving upwards, includes a substrate 321, a first electrode 322, a hole injection layer 323, a hole transport layer 324, a blue QD (Qunatum Dot) layer 325, an electron transport layer 326, and a second electrode 327. Figure 2 In the example, the first electrode 322 and the second electrode 327 are the anode and cathode, respectively. The second electrode 327 is translucent in a manner that allows blue light emitted from the blue QD layer 325 to pass through (for convenience, referred to as LB).

[0054] The blue QD layer 325 is a light-emitting layer (blue QD phosphor particle layer) containing blue QD phosphor particles not shown. In the excitation light source 320, as a voltage is applied between the first electrode 322 and the second electrode 327, holes are supplied from the first electrode 322 to the QD layer 325, and electrons (free electrons) are supplied from the second electrode 327 to the QD layer 325. The blue QD phosphor particles emit LB as the holes recombine with the electrons. In this way, the QD layer 325 emits light by EL (more specifically, injection-type EL). As an example, the wavelength range of the LB is 457 nm to 477 nm, and the peak wavelength of the LB is 467 nm.

[0055] In the excitation light source 320, the QD layer 325 (and the corresponding layers) is divided into three partial regions (SEC1 to SEC3) in the horizontal direction. More specifically, in the excitation light source 320, a plurality of switching elements are provided in SEC1 to SEC3 in a manner that enables separate voltages to be applied to the QD layer 325. As an example of the switching element, a thin film transistor (TFT) can be cited. Thereby, the light-emitting state of the QD layer 325 can be individually controlled in each of SEC1 to SEC3. Hereinafter, the LB emitted from SEC1 to SEC3 will be referred to as LB1 to LB3, respectively. In the example of FIG. 3, the LB1 to LB3 are emitted in the order of LB1, LB2, and LB3. Figure 2 Figure 2 In the example of FIG. 3, SEC1 is set as RSUB, SEC2 is set as GSUB, and SEC3 is set as a partial region corresponding to BSUB, respectively.

[0056] The phosphor member 330 is provided above the excitation light source 320 at positions corresponding to SEC1 to SEC3. The phosphor member 330 converts the wavelength of a part (LB1 and LB2) of the LB emitted from the QD layer 325. More specifically, the phosphor member 330 emits fluorescent light of a color different from blue (third color) as excitation light of LB1 and LB2. In Embodiment 1, the phosphor member 330 emits fluorescent light of red (first color) and green (second color). In addition, in Embodiment 1, excitation light of blue (third color) is emitted by the excitation light source 320.

[0057] ​In the present specification, light of the first color to light of the third color are referred to as first light to third light, respectively. Further, the second light has a shorter peak wavelength than the first light. Further, the third light has a shorter peak wavelength than the second light. Then, in the present specification, components that emit the first light to the third light are referred to as first light-emitting component to third light-emitting component, respectively. Further, phosphor components that emit the first light to the third light as phosphor light are referred to as first phosphor component to third phosphor component (first wavelength conversion component

[0058] In Embodiment 1, the red phosphor component 331R and the green phosphor component 331G described below are examples of the first light-emitting component and the second light-emitting component (more specifically, the first phosphor component and the second phosphor component), respectively. Thus, LR and LG of FIG. 2 are examples of the first light and the second light, respectively. Also, in Embodiment 1, the excitation light source 320 is an example of the third light-emitting component. Thus, Figure 2 LB (more specifically, LB3) in FIG. 1B is an example of the third light. Examples of the third phosphor component are described in Embodiment 3 described later.

[0059] The phosphor component 330 has a red phosphor component 331R (red wavelength conversion component) and a green phosphor component 331G (green wavelength conversion component). The red phosphor component 331R is disposed at a position corresponding to SEC1. The red phosphor component 331R includes a red QD phosphor particle not shown. The red QD phosphor particle receives LB1 as excitation light, thereby emitting red light (LR) as phosphor light. In this way, the red phosphor component 331R converts LB1 to LR, which is phosphor light having a longer peak wavelength than the LB1. As an example, the wavelength range of LR is 620 nm to 640 nm, and the peak wavelength of LR is 630 nm. In Figure 2 In the example of FIG. 1A, in SEC1, LR of the red CF 341R described below is emitted to the display panel 35.

[0060] Similarly, the green phosphor component 331G is disposed at a position corresponding to SEC2. The green phosphor component 331G includes a green QD phosphor particle not shown. The green QD phosphor particle receives LB2 as excitation light, thereby emitting green light (LG) as phosphor light. In this way, the green phosphor component 331G converts LB2 to LG, which is phosphor light having a longer peak wavelength than the LB2. Further, as can be clear from the correspondence relation of each color, the peak wavelength of LG is shorter than the peak wavelength of LR. As an example, the wavelength range of LG is 522 nm to 542 nm, and the peak wavelength of LG is 532 nm. In Figure 2 ​In the example, in SEC2, the LG emits light through the green CF341G as described below to the display panel 35.

[0061] As described above, the red phosphor component 331R and the green phosphor component 331G, unlike the blue QD layer 325, emit light via PL. The light amounts of LR and LG can be varied by adjusting the light amounts of LB1 and LB2, which serve as excitation light. Furthermore, the afterglow time of LB (fluorescence generated by EL) is shorter than that of LR and LG (fluorescence generated by PL).

[0062] like Figure 2 As shown, the phosphor component 330 also has a blue light transmitting layer 331B at the position corresponding to SEC3. The blue light transmitting layer 331B allows LB3 to be transmitted. The material of the blue light transmitting layer 331B is not particularly limited, but it is preferably a material with particularly high light transmittance at least in the blue band (e.g., transparent glass or resin).

[0063] In addition, Figure 2 In the example, the CF component 340 also has a blue light transmitting layer 341B, which is the same as the blue light transmitting layer 331B described above, at the position corresponding to SEC3. Therefore, LB3, through the blue light transmitting layers 331B and 341B, emits light into the display panel 35. However, in the light-emitting element 310, a blue CF may be further provided instead of the blue light transmitting layer 341B of the CF component 340.

[0064] As described above, the light-emitting element 310 can supply the display panel 35 with light (mixed light) that is a mixture of LR, LG, and LB3. Therefore, by appropriately adjusting the light amounts of LR, LG, and LB3, the desired hue can be expressed using the mixed light. In Embodiment 1, the case where the light-emitting element 310 emits white light (more precisely, near-white light) as the mixed light is illustrated. This is also the case in Embodiment 3, which will be described later.

[0065] Furthermore, by using the blue QD layer 325 as a blue light source in the light-emitting element 310, the half-width at half-maximum (WWHM) of the blue light and the fluorescence peak wavelength can be precisely controlled. That is, the monochromaticity of the blue light (LB3) in the BSUB can be improved. Similarly, by using the red phosphor component 331R and the green phosphor component 331G as the red and green light sources respectively, the monochromaticity of the red light (LR) in the RSUB and the green light (LG) in the GSUB can be improved respectively. Therefore, based on the light-emitting element 310, a display device 1 with excellent display quality (especially color reproduction) can be achieved.

[0066] However, the phosphor member 330 does not necessarily convert all of the LB received in the SEC1 and the SEC2 into light of different wavelengths. Specifically, the red phosphor member 331R does not necessarily convert all of the LB1 into the LR. That is, a part of the LB1 is not absorbed by the red phosphor member 331R and passes through the red phosphor member 331R. Similarly, a part of the LB2 is not absorbed by the green phosphor member 331G and passes through the green phosphor member 331G. Hereinafter, the LB1 that has passed through the red phosphor member 331R will be referred to as first residual blue light. In addition, the LB2 that has passed through the green phosphor member 331G will be referred to as second residual blue light.

[0067] Therefore, in the light emitting element 310 of the example, Figure 2 of the example, in order to reduce the influence of the first residual blue light and the second residual blue light, the CF member 340 is provided above the phosphor member 330. More specifically, the CF member 340 is provided so as to cover the phosphor member 330 from a case where the display panel 35 is viewed.

[0068] The CF member 340 has a red CF 341R and a green CF 341G. In order to reduce the influence of the first residual blue light in the RSUB, the red CF 341R is provided at a position corresponding to the SEC1 (a position corresponding to the red phosphor member 331R). Similarly, in order to reduce the influence of the second residual blue light in the GSUB, the green CF 341G is provided at a position corresponding to the SEC2 (a position corresponding to the green phosphor member 331G).

[0069] The red CF 341R has a high light transmittance in the red wavelength band, and has a relatively low light transmittance in other wavelength bands. The green CF 341G has a high light transmittance in the green wavelength band, and has a low light transmittance in other wavelength bands. It is preferable that both the red CF 341R and the green CF 341G have particularly low transmittances in the blue wavelength band.

[0070] By providing the CF member 340, (i) the first residual blue light that is to be directed toward the display panel can be blocked by the red CF 341R, and (ii) the second residual blue light that is to be directed toward the display panel can be blocked by the green CF 341G. Therefore, it is possible to further improve the respective monochromacies of the LR and the LG in the display portion 30. Therefore, it is possible to further improve the display quality of the display device 1. However, depending on the display quality required of the display device 1, the CF member 340 can be omitted. This is the same with respect to the CF member 440 of Embodiment 3 described later.

[0071] Of course, the configuration of the light emitting element 310 is not limited to Figure 2For example, the light-emitting element 310 can be implemented using any known configuration. For instance, it can also be implemented using... Figure 3 The example demonstrates a simpler configuration for implementing the light-emitting element 310. As an example, the light-emitting element 310 could also be a light-emitting element in which a blue LED (blue excitation source), a red phosphor component (red wavelength conversion component), and a green phosphor component (green wavelength conversion component) are encapsulated within a single package.

[0072] (Example of the brightness distribution of the light-emitting element 310)

[0073] Figure 3 This is a diagram showing the correspondence between the light-emitting region 305 and the light-emitting element 310 in BL31. As described above, in Figure 3 In the example, a light-emitting region 305 corresponds to a light-emitting element within that region 305. Figure 3 In the example, the subscript i represents the row position in BL31, and the subscript j represents the column position. i is an integer satisfying 1 ≤ i ≤ I². j is an integer satisfying 1 ≤ j ≤ J².

[0074] The row and column directions in BL31 correspond to the affected row (vertical) and column (horizontal) directions, respectively. Therefore, the row and column directions in BL31 also correspond to the row and column directions in display panel 35, respectively. Figure 3 In the example, the light-emitting region 305 located in the i-th row and j-th column of BL31 is labeled REG(i,j). Furthermore, the light-emitting element 310 of REG(i,j) is labeled LS(i,j). Figure 3 In the diagram, white circles represent light-emitting elements 310 that are in the lit state (light-emitting state), and black circles represent light-emitting elements 310 that are in the off state (non-light-emitting state).

[0075] As described above, in the display device 1, the brightness of the light-emitting element 310 is controlled according to the image signal. Furthermore, in the following description, "brightness of the light-emitting element 310" can be appropriately replaced with "brightness of the light-emitting area 305". As an example, consider the case where the image represented by the image signal is a white window pattern with a black background. In this case, the control unit 10 illuminates the light-emitting element 310 located at the position corresponding to the white window pattern.

[0076] exist Figure 4 In this example, a 3×3 rectangular area centered at REG(3,5) corresponds to the white window pattern. In this case, the control unit 10 illuminates the following nine light-emitting elements:

[0077] • LS(2, 4), LS(2, 5), LS(2, 6);

[0078] • LS(3, 4), LS(3, 5), LS(3, 6);

[0079] • LS(4, 4), LS(4, 5), LS(4, 6).

[0080] On the other hand, the control section 10 turns off the light emitting element 310 other than the nine light emitting elements.

[0081] Figure 4 is a graph for explaining the luminance distribution of the light emitting element 310. Figure 4 Reference numeral 4100 in indicates an example of a two-dimensional luminance distribution of one light emitting element 310 in the light-on state. As indicated by reference numeral 4100, the luminance of the light emitting element 310 takes a peak value at the center position of the light emitting element 310, and decreases as it moves away from the center position. In the display device 1, the luminance distribution is modeled by a PSF (Point Spread Function) set in advance. Figure 4 Reference numeral 4200 in indicates a graph that expresses the luminance distribution in reference numeral 4100 by a one-dimensional graph. As an example, the horizontal axis "Position" of the graph indicates the position in the row direction or the column direction of the BL 31. In this case, the graph shows the luminance distribution of one light emitting element 310 in the row direction or the column direction of the BL 31.

[0082] Figure 1 Reference numeral 4300 in is a graph that indicates one-dimensional luminance distributions of a plurality of (for example, three) light emitting elements 310 in the light-on state. The graph of reference numeral 4300 is paired with the graph of reference numeral 4200. As an example, in the following description, let LS(2, 4), LS(2, 5), and LS(2, 6) be the above three light emitting elements 310.

[0083] DisA, DisB, and DisC in reference numeral 4300 respectively indicate the luminance distributions of LS(2, 4), LS(2, 5), and LS(2, 6). As indicated by reference numeral 4300, DisB is obtained by shifting DisA to the right by only one light emitting element 310 distance. Similarly, DisC is obtained by shifting DisB to the right by only one light emitting element 310 distance. In other words, DisC is obtained by shifting DisA to the right by only two light emitting element 310 distances.

[0084] In the display device 1, the luminance distributions of the light emitting elements 310 are set in advance so as to respectively show The PSF of the display device 1. Moreover, in the display device 1, the luminance distribution of the three light emitting elements 310 (DisT in the graph of the reference sign 4300) is calculated by performing an operation of adding DisA, DisB, and DisC.

[0085] In the display device 1, a distribution of luminance of light irradiated from the BL 31 to each of the plurality of display pixels 350 (BL luminance distribution) is calculated on the basis of the PSF by a known calculation model. The calculation model is constructed so as to reproduce an actual luminance distribution of the BL 31. As described below, in the display device 1, the display panel 35 is controlled on the basis of the BL luminance distribution in addition to the image signal.

[0086] (BL luminance calculation section 11)

[0087] Referring again to Figure 5 The operation of each section of the control section 10 will be described. The BL luminance calculation section 11 generates BL luminance data on the basis of the image signal acquired from the image signal acquisition section 20. The BL luminance data refers to data indicating the luminance of the BL 31 in each frame period of the image.

[0088] As described above, the BL 31 in Embodiment 1 is an LD-type BL. Therefore, the BL luminance calculation section 11 generates BL luminance data for the LD-type BL on the basis of the image signal. In a specific example, the BL luminance calculation section 11 generates BL luminance data indicating the luminance of LS(1, 1) to LS(I2, J2) in each frame period. The BL luminance calculation section 11 supplies the generated BL luminance data to the BL luminance filter operation section 12.

[0089] (BL luminance filter operation section 12)

[0090] The BL luminance filter operation section 12 corrects the BL luminance data using a known filter (example: digital filter). More specifically, the BL luminance filter operation section 12 smoothes the BL luminance data using the filter. Hereinafter, the BL luminance data corrected by the BL luminance filter operation section 12 will be referred to as corrected BL luminance data. The BL luminance filter operation section 12 supplies the corrected BL luminance data to the BL 31 and the BL luminance distribution calculation section 131.

[0091] The filter in the BL luminance filter operation section 12 is not particularly limited as long as it can smooth the BL luminance data. For example, the filter can be a filter that can delay the temporal change of the BL luminance data according to an arbitrary set time constant. Therefore, for example, a known low-pass filter can be applied as the filter for smoothing the BL luminance data.

[0092] As a specific example of the above-described color filter, an IIR (Infinite Impulse Response) color filter or an FIR (Finite IR) color filter can be given. In addition, in order to reduce the amount of calculation in the color filter, an IIR color filter is preferably used. The above description regarding the color filter in the BL luminance color filter operation section 12 is also equally applicable to the BL luminance distribution color filter operation section 132 described later.

[0093] In general, the response speed of the display panel 35 (panel response speed) is lower than the response speed of the BL 31 (BL response speed). Therefore, in a case where the BL 31 is driven in accordance with the BL luminance data, flicker can occur in the display section 30 due to the difference between the BL response speed and the panel response speed. In particular, in a case where a scene switch occurs in the video, the possibility of occurrence of flicker is high. This reduces the display quality of the video displayed on the display section 30, and thus is not preferable for the display device 1.

[0094] Therefore, in Embodiment 1, the control section 10 drives the BL 31 in accordance with the BL luminance data after the correction. As a specific example, the control section 10 drives the LS(1, 1) to LS(I2, J2) in accordance with the corrected BL luminance data. By driving the BL 31 in this way, it is possible to reduce the difference between the BL response speed and the panel response speed. Therefore, it is possible to improve the display quality of the video displayed on the display section 30.

[0095] (BL luminance distribution calculation section 131)

[0096] Next, each section of the display pixel data generation section 13 will be described. The BL luminance distribution calculation section 131 calculates the BL luminance distribution based on (i) the corrected BL luminance data acquired from the BL luminance color filter operation section 12 and (ii) a PSF set in advance.

[0097] In the display device 1, the PSF is set with respect to the color of the mixed light (for convenience, referred to as mixed color) emitted from the light emitting element 310. As described above, the mixed color in the example of Embodiment 1 is white. Therefore, in Embodiment 1, the display pixel data generation section 13 calculates the BL luminance distribution of white light. In this specification, the BL luminance distribution of white light is denoted by f(W). f(W) is an example of the mixed light BL luminance distribution involved in one embodiment of the present disclosure. The mixed light BL luminance distribution means the distribution of the luminance of the mixed light irradiated from the BL 31 to each of the plurality of display pixels 350. The display pixel data generation section 13 supplies f(W) calculated during each frame to the BL luminance distribution color filter operation section 132.

[0098] (BL luminance distribution color filter operation section 132)

[0099] Figure 5 is a diagram showing a configuration example of the BL brightness distribution filter operation section 132. The BL brightness distribution filter operation section 132 smoothes f(W) using a known filter, thereby calculating a first light BL brightness distribution, a second light BL brightness distribution, and a third light BL brightness distribution. The first light BL brightness distribution refers to a brightness distribution of the first light that is respectively irradiated from the BL 31 to the plurality of display pixels 350. The same definition applies to the second light BL brightness distribution and the third light BL brightness distribution. The BL brightness distribution filter operation section 132 supplies the calculated first light BL brightness distribution The third light BL brightness distribution is supplied to the transmittance decision section 133.

[0100] In Figure 5 In the example, the BL brightness distribution filter operation section 132 smoothes f(W) by an IIR filter. Figure 5 In the example, the BL brightness distribution filter operation section 132 smoothes f(W) by an IIR filter.

[0101] H(z) = a0 / (1 - bl x z -1 )... (1)

[0102] using a transfer function H(z) represented by

[0103] Figure 6 The BL brightness distribution filter operation section 132 of the BL brightness distribution filter operation section 132 in the example has amplifiers 1321a, 1321b, a frame delay circuit 1322, and an adder 1323. As is clear to those skilled in the art, these functional sections are connected to each other to realize H(z) of formula (1). The respective gains of the amplifiers 1321a, 1321b are a0and bl. These gains are variable. The frame delay circuit 1322 outputs data held in the previous frame period during the next frame period.

[0104] Here, a time constant of the filter having the transfer function of formula (1) is represented as τ. As is clear to those skilled in the art, between τ and bl,

[0105] bl = exp(-t / τ)... (2)

[0106] This relationship holds. t is a frame period of the image. t is the inverse of the frame rate f of the image. In Embodiment 1, f = 120 Hz. Therefore, in Embodiment 1, t = 8.34 ms. As is clear from formula (2), in the BL brightness distribution filter operation section 132, by appropriately selecting the value of bl, a desired τ can be obtained.

[0107] For example, consider the case where τ = 10 ms is set in the BL luminance distribution filter operation section 132. In this case, bl = exp(-0.834) = 0.434 can be set. Thus, a0 = 1 / (1.434) = 0.697 can be set. In this way, τ can be set to a desired value by adjusting the respective gains of the amplifiers 1321a, 1321b.

[0108] The BL luminance distribution filter operation section 132 can be configured to adjust the respective gains of the amplifiers 1321a, 1321b so as to correspond to a desired τ according to Equation (2). In other words, the BL luminance distribution filter operation section 132 can also set τ according to the frame rate. In this way, the BL luminance distribution filter operation section 132 can also be configured to be able to set at least one of the first time constant, the second time constant, and the third time constant described later according to the frame rate.

[0109] It is known that in most cases (particularly in cases where a luminescent material having excellent monochromaticity is used), the afterglow time of light having a long wavelength is longer than the afterglow time of light having a short wavelength. Thus, for example, in most cases, the afterglow time of the first light (e.g., LR) is longer than the afterglow time of the second light (e.g., LG) and the third light (e.g., LB). As an example, in the luminescent element 310 of Embodiment 1, the afterglow time of LR is about 100 to 1000 times longer than the afterglow times of LG and LB. More specifically, the afterglow time of LR is on the order of tens of ms.

[0110] In view of this, it can be said that in order to improve the display quality of the display device 1, it is preferable to drive the display panel 35 in a manner that eliminates the influence of the afterglow of LR. Thus, in Embodiment 1, the BL luminance distribution filter operation section 132 smoothes f(W) by H(z) and thus calculates the red light BL luminance distribution f(R). f(R) is an example of a first light BL luminance distribution.

[0111] Figure 6 An example of f(R) calculated by the BL luminance distribution filter operation section 132 is shown. Figure 5 The horizontal axis in the graph of f(R) is the time. Figure 5 f(W) in the example of Embodiment 1 is a step function that takes a High value (corresponding to the lighting of the luminescent element 310) during the period from time t1 to t2. As shown in FIG. 6, f(R) is calculated as a function representing a first-order lag response in which f(W) is delayed by the time constant τ. Figure 5

[0112] ​In the present specification, the time constant used for calculating the first light BL luminance distribution is referred to as a first time constant. In particular, the time constant used for calculating f(R) is referred to as a red light time constant (τR). The red light time constant is an example of the first time constant. As described above, in Embodiment 1, for example, τR = 10 ms is set. The value of τR, which takes into account the afterglow time of LR, can be appropriately set by the designer of the display device 1.

[0113] However, as made clear from the above description, in Embodiment 1, the afterglow times of LGand LBare sufficiently short compared to the afterglow time of LR. Therefore, regarding the afterglow times of LGand LB, it is considered that there is no influence even if they are approximately regarded as 0. Therefore, as an example, the BL luminance distribution filter operation section 132 can set the green light BL luminance distribution f(G) and the blue light BL luminance distribution f(B) to be equal to f(W).

[0114] As understood from the above description, in Embodiment 1, the BL luminance distribution filter operation section 132 makes Figure 6 Figure 6 f(G) = f(B) = f(G, B) = f(W)... (3)

[0115] f(G) = f(B) = f(G, B) = f(W)... (3)

[0116] f(G) and f(B) are set. f(G) and f(B) are examples of the second light BL luminance distribution and the third light BL luminance distribution, respectively. f(G, B) is the BL luminance distribution common to the green light and the blue light. f(G, B) is referred to as a green / blue light BL luminance distribution.

[0117] As described above, the second light BL luminance distribution and the third light BL luminance distribution can also be set to a common (identical) distribution. In the present specification, this common luminance distribution is referred to as a second / third light BL luminance distribution. The above-described f(G, B) is an example of the second / third light BL luminance distribution.

[0118] In the present specification, the time constant used for calculating the second light BL luminance distribution is referred to as a second time constant. In particular, the time constant used for calculating f(G) is referred to as a green light time constant (τG). The green light time constant is an example of the second time constant. Similarly, the time constant used for calculating the third light BL luminance distribution is referred to as a third time constant. In particular, the time constant used for calculating f(B) is referred to as a blue light time constant (τΒ).

[0119] ​In a case where the second light BL luminance distribution and the third light BL luminance distribution are set as the second / third light BL luminance distribution, the second time constant and the third time constant are equal. However, of course, the second time constant and the third time constant can also be set to different values. For example, the second time constant can also be set to a value larger than the third time constant.

[0120] As can be understood from the above description, in most cases, the first time constant is preferably set to a value larger than the second time constant and the third time constant. In view of this point, in Embodiment 1, f(G) and f(B) of the above-described formula (3) are set. In this case, as can be understood from the above description, f(G) and f(B) are set to τG= τB= τ(G, B)= 0 ms (time constant zero). Figure 5 As can be understood from the above description, f(G) and f(B) are set to τG= τB= τ(G, B)= 0 ms (time constant zero).

[0121] As described above, in Embodiment 1, the BL luminance distribution filter operation section 132 does not delay f(W) but outputs f(W) directly as f(G, B) (also refer to the above-described description of Figure 5 ). In other words, the BL luminance distribution filter operation section 132 generates f(G, B) by applying a filter (identity filter) having a transfer function C(z)= 1 to f(W). The identity filter can also be expressed as a filter having a time constant of 0 and a gain of 1.

[0122] In addition, in the present specification, "the BL luminance distribution filter operation section 132 applies an identity filter to f(W) to generate f(G, B)" also includes "the BL luminance distribution filter operation section 132 does not delay f(W) but outputs f(W) directly as f(G, B)". Thus, it is desired to note that, in the BL luminance distribution filter operation section 132, the identity filter is not necessarily installed as an actual hardware element or a software element (also refer to the above-described description of Figure 1 ).

[0123] (Transmittance determination section 133)

[0124] The transmittance determination section 133 (i) acquires the image signal from the image signal input section, and (ii) acquires the first light BL luminance distribution to the third light BL luminance distribution from the BL luminance distribution filter operation section 132. The transmittance determination section 133 acquires the image signal and f(R) and f(G, B) in the example of Figure 7 . The transmittance determination section 133 generates display pixel data (example: liquid crystal pixel data) based on the image signal and the first light BL luminance distribution to the third light BL luminance distribution. The display pixel data refers to data indicating the transmittance of each of the plurality of display pixels 350.

[0125] In Embodiment 1, the transmittance determining section 133 generates display pixel data including first display sub-pixel data (e.g., red display sub-pixel data), second display sub-pixel data (e.g., green display sub-pixel data), and third display sub-pixel data (e.g., blue display sub-pixel data). The first display sub-pixel data refers to data indicating the transmittance of each of the plurality of first display sub-pixels. The same definition applies to the second display sub-pixel data and the third display sub-pixel data.

[0126] The transmittance determining section 133 obtains the luminance value of each of the first color to the third color in the image from the image signal. In Embodiment 1, the transmittance determining section 133 obtains the luminance value d(R) of red, the luminance value d(G) of green, and the luminance value d(B) of blue in the image.

[0127] Also, the transmittance determining section 133 determines the transmittance g(R) of the red display sub-pixel based on d(R) and f(R). In Embodiment 1, the transmittance determining section 133 calculates g(R) by dividing d(R) by f(R). That is, the transmittance determining section 133 calculates g(R) as follows.

[0128] g(R) = d(R) / f(R) … (4)

[0129] g(R) is calculated.

[0130] Similarly, the transmittance determining section 133 calculates the transmittance g(G) of the green display sub-pixel based on (i) d(G) and f(G), and calculates the transmittance g(B) of the blue display sub-pixel based on (ii) d(B) and f(B). As described above, in Embodiment 1, f(G) = f(B) = f(G, B).

[0131] Therefore, the transmittance determining section calculates g(G) and g(B) as follows.

[0132] g(G) = d(G) / f(G) = d(G) / f(G) / f(G, B) … (5)

[0133] g(B) = d(B) / f(B) = d(B) / f(G, B) … (6)

[0134] g(G) and g(B) are calculated respectively.

[0135] The transmittance determining section 133 generates (i) data indicating g(R) as the red display sub-pixel data, (ii) data indicating g(G) as the green display sub-pixel data, and (iii) data indicating g(B) as the blue display sub-pixel data, respectively.

[0136] The control section 10 drives the display panel 35 in accordance with the display pixel data. Specifically, the control section 10 drives each of the plurality of display pixels 350 in accordance with the display pixel data. More specifically, the control section 10 drives the RSUB, GSUB, and BSUB of each of the plurality of display pixels 350 in accordance with the red display sub-pixel data, the green display sub-pixel data, and the blue display sub-pixel data.

[0137] As described above, the display pixel data generation section 13 generates the display pixel data based on the BL luminance data and the image signal (in the example of Embodiment 1, based on the corrected BL luminance data and the image signal). Thus, in the display device 1, the display panel 35 can be driven in coordination with the driving of the BL 31. In addition, the display pixel data generation section 13 generates the red display sub-pixel data, the green display sub-pixel data, and the blue display sub-pixel data using different time constants of τR= 10 ms and τ(G, B) = 0 ms. Thus, in the display device 1, the display panel 35 can be driven so as to eliminate the influence of the difference in the afterglow time of each color light. For example, in the display device 1, the display panel 35 can be driven so as to eliminate the influence of the afterglow of the LR.

[0138] (EFFECTS)

[0139] Figure 7 is a graph illustrating the relationship of the BL luminance, the panel transmittance (the transmittance of the display panel), and the display image luminance (the luminance of the image displayed by the display panel) in an ideal display device. In this ideal display device, the afterglow time of the red light, the green light, and the blue light is each 0. Figure 7 The liquid crystal transmittance in the graph G11 can also be replaced with the display pixel data.

[0140] Figure 7 The graph G11 of the BL luminance in the ideal display device illustrates an example of the time variation of the BL luminance. In the example of G11, the BL luminance takes a High value from time t1 to t2. As an example, in the case where t1 to t2 is a period during which a bright scene of the display image is displayed, such a time variation of the BL luminance occurs. On the other hand, as illustrated in the graph G12, the panel transmittance is constant regardless of the time. In the following description of the graph G12, Figure 8 The graph G12 illustrates an example of the time variation of the panel transmittance in the ideal display device. In the example of G12, the panel transmittance is constant regardless of the time. In the following description of the graph G12, Figure 9 and Figure 7 In the following description of the graph G12, the panel transmittance is also as illustrated in G12.

[0141] Figure 8A graph G13 shows an example of the time change of the display image luminance in an ideal display device. The display image luminance is defined by the product of the BL luminance and the panel transmittance. Therefore, as shown in G13, in the ideal display device (i.e., in the case where the afterglow time of the red light, the green light, and the blue light are all equal), the manner of the time change of the display image luminance coincides with the manner of the time change of the BL luminance.

[0142] Figure 8 A graph G21 shows an example of the time change of the BL luminance in Comparative Example 1. In G21, the solid line indicates the green-blue light, and the broken line indicates the red light. This is the same in each of the graphs hereinafter. As shown in G21, in tl, the green-blue light luminance (the luminance of the green-blue light) rapidly rises to the High value. On the other hand, the red light luminance (the luminance of the red light) increases slowly compared with the green-blue light luminance. In the example of G21, at time tla, the red light luminance reaches the High value (refer to the portion S210 of G21). Thus, in Comparative Example 1, tl to tla is a period in which the influence of the green-blue light is greater than that of the red light.

[0143] Figure 8 A graph G23 shows an example of the time change of the display image luminance in Comparative Example 1. The manner of the time change of the luminance of each color light in the display image is defined by the product of each color luminance of the BL light and the panel transmittance. Therefore, in tl to tla, even in the display image, the green-blue light luminance is greater than the red light luminance. As a result, in tl to tla, the display image produces a green-blue coloration corresponding to S210 described above (refer to the portion S230 of G23). Similarly, in t2 to t2a, the display image produces a red coloration corresponding to S211 described above (refer to the portion S231 of G23). Figure 8 Figure 8

[0144] Figure 8

[0145] Figure 9 A graph G23 shows an example of the time change of the display image luminance in Comparative Example 1. The manner of the time change of the luminance of each color light in the display image is defined by the product of each color luminance of the BL light and the panel transmittance. Therefore, in tl to tla, even in the display image, the green-blue light luminance is greater than the red light luminance. As a result, in tl to tla, the display image produces a green-blue coloration corresponding to S210 described above (refer to the portion S230 of G23). Similarly, in t2 to t2a, the display image produces a red coloration corresponding to S211 described above (refer to the portion S231 of G23). ​​​​

[0146] Figure 9 is a graph that explains the relationship between the BL luminance, the panel transmittance, and the display image luminance in the display device of Patent Literature 1 (for convenience, referred to as Comparative Example 2). The display device of Patent Literature 1 is an example of a technology for solving the problem point in Comparative Example 1. Specifically, the display device of Patent Literature 1, in order to reduce the coloring of the display image, adds an analog afterglow signal to the image signal. In other words, the display device of Patent Literature 1, in order to reduce the coloring of the display image, causes the BL to generate an analog afterglow signal (analog afterglow).

[0147] Figure 9 The graph G31 of Comparative Example 2 indicates an example of the time variation of the BL luminance in Comparative Example 2. As indicated by G31, in Comparative Example 2, in tl to tla, in order to completely eliminate the influence of the delay of the rise of the red luminance, an analog afterglow of green and blue (refer to the portion S310 of G31) is added in a manner that the rise of the analog emission of green and blue is delayed. In addition, in Comparative Example 2, in t2 to t2m, in order to reduce (partially eliminate) the influence of the delay of the fall of the red luminance, an analog afterglow of green and blue (refer to the portion S311 of G31) is added in a manner that the fall of the analog emission of green and blue is delayed. t2m < t2a.

[0148] Figure 10 The graph G33 of Comparative Example 2 shows an example of the time variation of the display image luminance in Comparative Example 2. In Comparative Example 2, in tl to tla, the coloring of green and blue in the display image is eliminated in correspondence with the above-described S310 (refer to the portion S330 of G33). In addition, in Comparative Example 2, in t2 to t2a, the coloring of red in the display image is reduced in correspondence with the above-described S311. In this way, in Comparative Example 2, the coloring in the display image is reduced (refer to the portion S331 of G33). In addition, in Comparative Example 2, whether or not the coloring of each color in the display image can be completely eliminated depends on the maximum value of the luminance of the analog afterglow that can be generated.

[0149] However, in Comparative Example 2, with the addition of the analog afterglow signal to the image signal, the display device presents the display image that is different from the original to the user. In this way, the method of Comparative Example 2, "in order to reduce the coloring in the display image, an analog afterglow signal is added to the image signal", is worried to have a drawback from the viewpoint of the reproducibility of the image.

[0150] In view of this, the inventors of the present application (hereinafter, simply referred to as "the inventors") have had the idea of "preferably reducing the coloring in the display image by a method different from Comparative Example 2". The display device 1 is newly created by the inventors based on this idea.

[0151] Figure 10 is a graph illustrating the relationship between the BL luminance, the panel transmittance, and the display image luminance of the display device 1. In Figure 10 In the example of the display device 1, the time variation of the BL luminance is set to be the same as that of Comparative Example 1. That is, in the display device 1, unlike Comparative Example 2, no analog afterglow signal is added to the image signal (in other words, no analog afterglow is generated by the backlight).

[0152] Figure 10 The graph G42 shows an example of the time variation of the liquid crystal transmittance in the display device 1. As described above, the display device 1 generates the red display sub-pixel data, the green display sub-pixel data, and the blue display sub-pixel data based on the corrected BL luminance data and the image signal. As shown in G42, in the display device 1, the coloring of the green and blue colors in the display image is eliminated in Figure 10 In the example of the display device 1, the green and blue light transmittances (the transmittances of the green and blue light), i.e., g(G) and g(B), are set to be constant values independent of the time. On the other hand, the red light transmittance (the transmittance of the red light), i.e., g(R), is set to vary with time corresponding to S210 and S211 described above.

[0153] Specifically, the red light transmittance in t1 to t1a is set to cancel the effect of the gradual increase in the red light luminance shown in S210. In Figure 10 In the example of the display device 1, the red light transmittance rapidly increases to the maximum at t1. Thereafter, until t1a, the red light transmittance linearly decreases (see the portion S420 of G42).

[0154] Similarly, the red light transmittance in t2 to t2a is set to cancel the effect of the gradual decrease in the red light luminance shown in S211. In Figure 10 In the example of the display device 1, the red light transmittance rapidly decreases to the minimum at t2. Thereafter, until t2a, the red light transmittance linearly increases (see the portion S421 of G42).

[0155] Figure 11 The graph G43 shows an example of the time variation of the display image luminance in the display device 1. In the display device 1, in t1 to t1a, the coloring of the green and blue colors in the display image is eliminated corresponding to S420 described above (see the portion S430 of G43). Further, in Comparative Example 2, in t2 to t2a, the coloring of the red color in the display image is reduced corresponding to S421 described above. In this way, in the display device 1, the coloring in the display image is also reduced.

[0156] In addition, in the display device 1, whether the coloring of each color in the display image can be completely eliminated or not depends on the display sub-pixel Figure 12the minimum value and the maximum value of the transmittance that can be achieved in the red display sub-pixel. For example, in S431, even the minimum value of the red light transmittance in the red display sub-pixel cannot completely cancel the influence of the maximum value of the red light luminance.

[0157] As described above, in the display device 1, the coloring in the displayed image is reduced by the method different from Comparative Example 2 of "generating each color display sub-pixel data in consideration of the different afterglow time of each color light". Thus, according to the display device 1, the display quality of the display device having a plurality of light emitting parts respectively emitting different colors can be improved by a method different from the past. Moreover, as understood from the above G43, according to the display device 1, a displayed image closer to the original image can be presented to the user compared to Comparative Example 2. Therefore, from the viewpoint of the reproducibility of the image, it can be said that the display device 1 is more suitable than Comparative Example 2.

[0158] (Variation)

[0159] Figure 12 is a block diagram showing a part of the configuration of a display device IV which is a variation of Embodiment 1. The display device IV has a display pixel data generating section 13V instead of the display pixel data generating section 13. In addition, the control section of the display device IV is referred to as a control section 10V (control device).

[0160] The display pixel data generating section 13V includes a second BL luminance filter operation section 134 and a BL luminance distribution calculating section 135 instead of the BL luminance distribution calculating section 131 and the BL luminance distribution filter operation section 132. The BL luminance distribution calculating section 135 has a first luminance distribution calculating section 136A and a second luminance distribution calculating section 136B.

[0161] The second BL luminance filter operation section 134 smoothes the corrected BL luminance data acquired from the BL luminance filter operation section 12 using a filter. In the second BL luminance filter operation section 134, similarly to the BL luminance distribution filter operation section 132 of Embodiment 1, τR= 10 ms and τ(G, B) = 0 ms are set.

[0162] The second BL brightness filter operation section 134 smoothes the corrected BL brightness data using τR, thereby generating red light corrected BL brightness data. The second BL brightness filter operation section 134 supplies the red light corrected BL brightness data to the first brightness distribution calculation section 136A. Then, the second BL brightness filter operation section 134 smoothes the corrected BL brightness data using τ(G, B), thereby generating green-blue light corrected BL brightness data. The second BL brightness filter operation section 134 supplies the green-blue light corrected BL brightness data to the second brightness distribution calculation section 136B.

[0163] The first brightness distribution calculation section 136A calculates f(R) from the red light corrected BL brightness data and the PSF. The first brightness distribution calculation section 136A supplies the calculated f(R) to the transmittance decision section 133. Similarly, the second brightness distribution calculation section 136B calculates f(G, B) from the green-blue light corrected BL brightness data and the PSF. The second brightness distribution calculation section 136B supplies the calculated f(G, B) to the transmittance decision section 133. The subsequent processing is the same as in Embodiment 1.

[0164] In Embodiment 1, f(W) is calculated from the corrected BL brightness data, and then f(W) is smoothed, thereby deriving f(R) and f(G, B). However, as in the display device IV, the smoothing processing can be performed before the brightness distribution is calculated, thereby deriving f(R) and f(G, B).

[0165] 〔Embodiment 2〕

[0166] Figure 5 is a view showing a configuration example of the BL brightness distribution filter operation section 132W of the display device 2 of Embodiment 2. Figure 13 is a view paired with Figure 13 . Note that the control section and the display pixel data generation section of the display device 2 are referred to as a control section 10W (control device) and a display pixel data generation section 13W, respectively. The BL brightness distribution filter operation section 132W further has a correction circuit 1324.

[0167] The BL luminance-distribution filter operation section 132W is different from the BL luminance-distribution filter operation section 132, and calculates f(G, B) by correcting f(W) using the correction circuit 1324. In the following description, the case where the current frame of the example image is the nth frame will be exemplified. n is an arbitrary integer. Then, f(W) in the current frame is denoted as f(W)(n). In the following description, the value of f(W)(n) will also be referred to as the BL value of the current frame. In contrast, the value of f(W) in the previous frame, i.e., f(W)(n-1), will also be referred to as the BL value of the previous frame. In addition, f(G, B) in the current frame is denoted as f(G, B)(n). In this specification, f(G, B) represents f(G, B)(n) unless specifically indicated otherwise.

[0168] The correction circuit 1324 (i) acquires f(W)(n) from the BL luminance-distribution calculation section 131, and (ii) acquires f(W)(n-1) from the frame delay circuit 1322. Then, the correction circuit 1324 corrects f(W)(n) using a correction table TBL that is set in advance.

[0169] In Embodiment 2, the correction circuit 1324 corrects f(W)(n) as follows on the right side of the following expression (7).

[0170] = TBL{f(W)(n-1), f(W)(n)} + f(W)(n)... (7),

[0171] By correcting f(W)(n), f(G, B)(n) is calculated. Hereinafter, the correction circuit 1324 supplies the calculated f(G, B) to the transmittance determination section 133.

[0172] Figure 13 FIG. 6 is a diagram showing an example of the TBL. In the TBL, the BL value of the previous frame and the BL value of the current frame are discretized into 11 levels (levels 0 to 10), respectively. In the example of FIG. 6, the greater the value indicating the level, the greater the BL value. Figure 13

[0173] In the example of FIG. 6, the TBL is set such that the absolute value of TBL{f(W)(n-1), f(W)(n)} is nonzero in the case where the BL value of the current frame greatly deviates from the BL value of the previous frame. Figure 14 Figure 14 ​​In the example, when the BL value of the current frame is 5 levels or more greater than the BL value of the previous frame, TBL{f(W)(n-1), f(W)(n)} takes a positive value (except when the BL value of the current frame is level 10). On the other hand, when the BL value of the current frame is 5 levels or more less than the BL value of the previous frame, TBL{f(W)(n-1), f(W)(n)} takes a negative value (except when the BL value of the current frame is level 0). Thus, the value of TBL{f(W)(n-1), f(W)(n)} is determined by the combination of f(W)(n-1) and f(W)(n).

[0174] As described above, the BL luminance distribution color filter calculation unit 132W can correct f(W)(n) based on the degree of deviation between f(W)(n) and f(W)(n-1), thereby calculating f(G, B). Furthermore, as can be clearly understood from the description of Embodiment 1, in Embodiment 2, f(G) and f(B) can also be calculated as separate BL luminance distributions. The BL luminance distribution color filter calculation unit 132W only needs to be able to calculate f(G) and f(B) by correcting f(W)(n).

[0175] (Effects of Implementation Method 2)

[0176] Figure 14 This is another example of the relationship between BL brightness, panel transmittance and displayed image brightness in display device 1. Figure 14 The example is a reference example of implementation method 2. Figure 14 Graph G51 shows an example of the time-varying brightness of BL in the reference example. Figure 14 In the example, at time t3, the brightness of the green and blue light rapidly decreases to a Low value. On the other hand, the brightness of the red light decreases slowly compared to the brightness of the green and blue light. Then, at time t3a, the brightness of the red light reaches a Low value (see part S510 of G51).

[0177] Figure 14 The graph G52 represents an example of the time-varying transmittance of the panel in the reference example. As described above, in the display device 1, the red light transmittance after t3 is set in a manner that counteracts the effect of the slow decrease in red light brightness shown in S510. Figure 14 In the example, the red light transmittance rapidly decreases to a minimum at t3. Afterward, up to t3a, the red light transmittance increases linearly (see section S520 of G52).

[0178] Figure 10The graph G53 shows an example of the time variation of the display image luminance in the reference example. In the display device 1, after t3, the coloring of red in the display image is reduced in correspondence with S520 (see the portion S530 of G53). However, in the example of the reference example, the coloring of red in the display image cannot be completely eliminated. Figure 15 In the example of the reference example, the coloring of red in the display image cannot be completely eliminated. Figure 15 In the example of the reference example, the coloring of red in the display image cannot be completely eliminated.

[0179] Figure 15 The graph G61 shows an example of the time variation of the BL luminance in the display device 2. In the display device 2, the time variation of the BL luminance is also the same as that of the reference example. Figure 13 The graph G62 shows an example of the time variation of the panel transmittance of the display device 2. In the display device 2, the red light transmittance after t3 is also set in the same manner as in the reference example in order to offset the slow reduction of the red light luminance shown in S510 (see the portion S620 of G62). Figure 15 Further, in the display device 2, f(G, B) is calculated in accordance with the above-described equation (7). That is, f(G, B) can be determined in accordance with the degree of divergence (e.g., the amount of change) between f(W)(n-1) and f(W)(n). Specifically, f(G, B) is determined in such a manner as to offset the influence of the sharp numerical change between f(W)(n-1) and f(W)(n) by calculating f(G, B) in accordance with the TBL. Therefore, in the display device 2, the green-blue light transmittance after t3 is further set in such a manner as to offset the slow reduction of the red light luminance shown in S510. In the example of the reference example, the green-blue light transmittance rapidly increases to the maximum value at t3. Thereafter, until t3a, the green-blue light transmittance linearly decreases (see the portion S621 of G62).

[0180] Further, in the display device 2, f(G, B) is calculated in accordance with the above-described equation (7). That is, f(G, B) can be determined in accordance with the degree of divergence (e.g., the amount of change) between f(W)(n-1) and f(W)(n). Specifically, f(G, B) is determined in such a manner as to offset the influence of the sharp numerical change between f(W)(n-1) and f(W)(n) by calculating f(G, B) in accordance with the TBL. Therefore, in the display device 2, the green-blue light transmittance after t3 is further set in such a manner as to offset the slow reduction of the red light luminance shown in S510. In the example of the reference example, the green-blue light transmittance rapidly increases to the maximum value at t3. Thereafter, until t3a, the green-blue light transmittance linearly decreases (see the portion S621 of G62). Figure 15 Further, in the display device 2, f(G, B) is calculated in accordance with the above-described equation (7). That is, f(G, B) can be determined in accordance with the degree of divergence (e.g., the amount of change) between f(W)(n-1) and f(W)(n). Specifically, f(G, B) is determined in such a manner as to offset the influence of the sharp numerical change between f(W)(n-1) and f(W)(n) by calculating f(G, B) in accordance with the TBL. Therefore, in the display device 2, the green-blue light transmittance after t3 is further set in such a manner as to offset the slow reduction of the red light luminance shown in S510. In the example of the reference example, the green-blue light transmittance rapidly increases to the maximum value at t3. Thereafter, until t3a, the green-blue light transmittance linearly decreases (see the portion S621 of G62). Figure 16 Further, in the display device 2, f(G, B) is calculated in accordance with the above-described equation (7). That is, f(G, B) can be determined in accordance with the degree of divergence (e.g., the amount of change) between f(W)(n-1) and f(W)(n). Specifically, f(G, B) is determined in such a manner as to offset the influence of the sharp numerical change between f(W)(n-1) and f(W)(n) by calculating f(G, B) in accordance with the TBL. Therefore, in the display device 2, the green-blue light transmittance after t3 is further set in such a manner as to offset the slow reduction of the red light luminance shown in S510. In the example of the reference example, the green-blue light transmittance rapidly increases to the maximum value at t3. Thereafter, until t3a, the green-blue light transmittance linearly decreases (see the portion S621 of G62).

[0181] ​ The graph G63 shows an example of the time variation of the display image luminance in the display device 2. In the display device 2, the coloring of red in the display image is eliminated by setting the green-blue light transmittance as described above in S621 on the basis of the setting of the red light transmittance as described above in S620 (see the portion S630 of G63). As described above, by changing not only the red light transmittance but also the green-blue light transmittance, the influence of the slow reduction of the red light luminance can be more effectively eliminated.

[0182] However, in the display device 2, it is desirable to pay attention to presenting a display image slightly different from the original to the user as the green-blue color light transmittance is set as in S621. For example, which one of the display devices 1 or 2 (in other words, which one of the BL brightness distribution filter operation sections 132 or 132W) is appropriately selected by a designer of the display device in accordance with a display quality required by the display device.

[0183] Embodiment 3

[0184] ​ is a functional block diagram showing a configuration of a main part of the display device 4 of Embodiment 3. A display section of the display device 4 is referred to as a display section 30U. The display section 30U has a BL 31U instead of the BL 31. The BL 31U has one light emitting region (hereinafter, simply referred to as a single light emitting region) capable of controlling brightness. The single light emitting region includes one light source (not shown), for example. As an example, the single light emitting region includes one light emitting element 310. The BL 31U is different from the BL 31 in that the BL 31U does not have an LD function. Thus, the BL 31U can be referred to as a non-LD type BL. Alternatively, the BL 31U can be referred to as a 0-dimensional dimming type BL. In this way, in the BL related to one embodiment of the present disclosure, I2=1 and J2=1 can also be satisfied.

[0185] In Embodiment 3, the BL brightness calculation section 11 generates BL brightness data for the non-LD type BL based on the image signal. As a specific example, the BL brightness calculation section 11 generates BL brightness data representing brightness of the one light emitting element 310, that is, brightness of LS(1, 1) in each frame period. The subsequent processing is the same as in Embodiment 1. As described above, the light emission control method of one embodiment of the present disclosure can also be applied to the non-LD type BL. According to Embodiment 3, the same effects as in Embodiment 1 can also be obtained.

[0186] As described above, the BL related to one embodiment of the present disclosure can have at least one light emitting region irradiating a plurality of display pixels. Further, the at least one light emitting region can have at least one light emitting element as a light source.

[0187] In each of the above-described embodiments, a display pixel 350 having a first display sub-pixel, a second display sub-pixel, and a third display sub-pixel is exemplified. However, the display pixel related to one embodiment of the present disclosure can have only a first display sub-pixel and a second display sub-pixel.

[0188] Therefore, one embodiment of the present disclosure relates to a light-emitting element including at least a first light-emitting component and a second light-emitting component. As an example, the light-emitting element (i) includes an excitation light source (e.g., the excitation light source 320) that emits second light (e.g., blue light) as excitation light as the second light-emitting component, and (ii) includes a phosphor component (e.g., a yellow phosphor component) that receives the second light to emit first light (e.g., yellow light) as fluorescent light as the first light-emitting component. In this case, the light-emitting element can emit white light as mixed light.

[0189] According to the above, one embodiment of the present disclosure relates to a display pixel data generation section (i) that can generate first display subpixel data (e.g., blue display subpixel data) using a first time constant and (ii) that can generate second display subpixel data (e.g., yellow display subpixel data) using a second time constant different from the first time constant.

[0190] In the above embodiments, an example in which a light-emitting element that emits light from a QD layer EL is used as an excitation light source is described. However, another light-emitting element such as an LED or an organic EL light-emitting element can be used as the excitation light source. In the above embodiments, an example in which a QD phosphor particle is used as a phosphor component is described. However, another phosphor component can be used.

[0191] 〔Example of implementation by software〕

[0192] The control modules (particularly, the control units 10 to 10W) of the display devices 1 to 4 can be implemented by logic circuits (hardware) formed in integrated circuits (IC chips) or the like or can be implemented by software.

[0193] In the latter case, the display devices 1 to 4 have a computer that executes a command of a program that realizes each function. The computer includes, for example, at least one processor (control device) and at least one storage medium that stores the program and is readable by the computer. The computer realizes the object of one embodiment of the present disclosure by the processor reading the program from the storage medium and executing the program. As the processor, for example, a CPU (Central Processing Unit) can be used. As the storage medium, for example, a "non-transitory tangible medium" such as a ROM (Read Only Memory) can be used, and a magnetic tape, a magnetic disk, a card, a semiconductor memory, a programmable logic circuit, and the like can be used. Further, a RAM (Random Access Memory) or the like that expands the program can be further included. Further, the program can be provided to the computer via any transmission medium (a communication network, a broadcast wave, and the like) that can transmit the program. Further, one embodiment of the present disclosure can be realized in the form of a data signal embedded in a carrier wave by electronic transmission of the program.

[0194] 〔Additional matters〕

[0195] One embodiment of the present application is not limited to the above-described embodiments, and various changes can be made within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of one embodiment of the present application. Further, new technical features can be formed by combining the technical means disclosed in each of the embodiments.

[0196] Explanation of reference numerals

[0197] 1, 1V, 2, 3 display device

[0198] 10, 10V, 10W control unit (control device)

[0199] 11 BL luminance calculation unit (backlight luminance calculation unit)

[0200] 12 BL luminance filter operation unit

[0201] 13, 13V, 13W display pixel data generation unit

[0202] 30, 30U display unit

[0203] 31, 31U BL (backlight)

[0204] 35 display panel

[0205] 131, 135 BL luminance distribution calculation unit

[0206] 132, 132W BL brightness distribution filter operation section

[0207] 133 transmittance determination section

[0208] 136A first brightness distribution calculation section

[0209] 136B second brightness distribution calculation section

[0210] 305 light emitting region

[0211] 310 light emitting element

[0212] 320 excitation light source (third light emitting section)

[0213] 325 blue QD layer

[0214] 330 phosphor section

[0215] 331 R red phosphor section (first light emitting section, first phosphor section)

[0216] 331 G green phosphor section (second light emitting section, second phosphor section)

[0217] 340 CF section

[0218] 350 display pixel

[0219] f(W) white light BL brightness distribution (mixed light backlight brightness distribution)

[0220] f(R) red light BL brightness distribution (first light backlight brightness distribution)

[0221] f(G, B) green / blue light BL brightness distribution (second light backlight brightness distribution, third light backlight brightness distribution)

[0222] LR red light (fluorescence, first light)

[0223] LG green light (fluorescence, second light)

[0224] LB, LB1 to LB3 blue light (excitation light, third light)

[0225] RSUB red display sub-pixel (first display sub-pixel)

[0226] GSUB green display sub-pixel (second display sub-pixel)

[0227] BSUB blue display sub-pixel (third display sub-pixel)

Claims

1. A control device that controls a display device, characterized by, The display device includes: a display panel having a display region in which a plurality of display pixels are arranged, and displaying an image based on an image signal; and a backlight having at least one light emitting region that irradiates the plurality of display pixels based on the image signal, the at least one light emitting region having at least one light emitting element as a light source, each of the plurality of display pixels having: a first display sub-pixel that displays a first color; a second display sub-pixel that displays a second color different from the first color; and a third display sub-pixel that displays a third color different from the first color and the second color, each of the at least one light emitting element having: a first light emitting part that emits first light that is light of the first color; a second light emitting part that emits second light that is light of the second color and has a shorter peak wavelength than the first light; a third light emitting part that emits third light that is light of the third color and has a shorter peak wavelength than the second light, the third light emitting part being an excitation light source that emits the third light as excitation light, the first light emitting part being a first phosphor part that receives the third light and emits the first light as phosphor light, the second light emitting part being a second phosphor part that receives the third light and emits the second light as phosphor light, each of the at least one light emitting element emitting, as mixed light, light obtained by mixing the first light, the second light, and the third light toward the plurality of display pixels, the control device includes: a backlight luminance calculation part that generates backlight luminance data based on the image signal; and a display pixel data generation part that generates display pixel data based on the backlight luminance data and the image signal, the display pixel data including: first display sub-pixel data corresponding to the first display sub-pixel; second display sub-pixel data corresponding to the second display sub-pixel; and third display sub-pixel data corresponding to the third display sub-pixel, the display pixel data generation part generating the first display sub-pixel data using a first time constant, generating the second display sub-pixel data using a second time constant different from the first time constant, and generating the third display sub-pixel data using a third time constant different from the first time constant.

2. The control device according to claim 1, characterized by the first time constant is greater than the second time constant and the third time constant.

3. The control device of claim 2, wherein the second time constant is equal to the third time constant.

4. The control device according to claim 3, characterized by the second time constant and the third time constant are 0.

5. The control device according to any one of claims 1 to 4, characterized by the display pixel data generation part sets at least one of the first time constant, the second time constant, and the third time constant in accordance with a frame rate of the image.

6. The control device according to any one of claims 1 to 5, wherein the display pixel data generation part calculates a mixed light backlight luminance distribution based on the backlight luminance data, the mixed light backlight luminance distribution being a luminance distribution of the mixed light irradiated from the backlight toward each of the plurality of display pixels; and The display pixel data generation section calculates a first light backlight luminance distribution, which is a luminance distribution of the first light irradiated from the backlight to each of the plurality of display pixels, by smoothing the mixed light backlight luminance distribution using the first time constant; The display pixel data generation section calculates a second light backlight luminance distribution, which is a luminance distribution of the second light irradiated from the backlight to each of the plurality of display pixels, by smoothing the mixed light backlight luminance distribution using the second time constant; The display pixel data generation section calculates a third light backlight luminance distribution, which is a luminance distribution of the third light irradiated from the backlight to each of the plurality of display pixels, by smoothing the mixed light backlight luminance distribution using the third time constant; The display pixel data generation section generates the display pixel data based on the first light backlight luminance distribution, the second light backlight luminance distribution, the third light backlight luminance distribution, and the image signal.

7. The control device according to claim 6, wherein The display pixel data generation section generates the first display sub-pixel data based on the first light backlight luminance distribution and a luminance value of the first color in the image; The display pixel data generation section generates the second display sub-pixel data based on the second light backlight luminance distribution and a luminance value of the second color in the image; The display pixel data generation section generates the third display sub-pixel data based on the third light backlight luminance distribution and a luminance value of the third color in the image.

8. The control device according to claim 6 or 7, characterized in that The second light backlight luminance distribution and the third light backlight luminance distribution are the same distribution.

9. The control device according to any one of claims 6 to 8, wherein n is an arbitrary integer, The display pixel data generation section corrects the mixed light backlight luminance distribution in an n-th frame of the image, based on a degree of divergence of the mixed light backlight luminance distribution in the n-th frame of the image and the mixed light backlight luminance distribution in an (n-1)-th frame of the image, and calculates the second light backlight luminance distribution and the third light backlight luminance distribution in the n-th frame.

10. A display device, characterized by comprising: including: the control device according to any one of claims 1 to 9; the display panel; and the backlight.

Images