Display device

Abstract

A display device improves display quality. A display device (10) includes a display panel (11) having a display surface (11DS), an image display section (13) that displays an image on the display surface based on gradation information included in image data supplied from an external source, an illumination device (12) having a plurality of light sources (15) that irradiate the display panel with light for display, a light source drive section (19) that drives the plurality of light sources based on luminance information included in the image data, an illuminance sensor (50) that detects external light and outputs a detection signal corresponding to the amount of detected external light, and a control section (30) that corrects the luminance information based on the detection signal to control the light source drive section in a manner that drives the plurality of light sources based on the corrected luminance information, and corrects the gradation information based on the detection signal to control the image display section in a manner that displays the image based on the corrected gradation information.

Description

Technical Field

[0001] The technology disclosed in this specification relates to display devices for improving display quality. Background Technology

[0002] Conventionally, as an example of a display device, the apparatus described in Patent Document 1 is known. Patent Document 1 describes an image processing apparatus (image processing IC) that processes signals used to display an image on a display device. The image processing IC described in Patent Document 1 includes: a brightness correction unit that performs brightness correction on an input image and generates an output image; a brightness average calculation unit that calculates the average brightness of the output image; a brightness average calculation unit that calculates the average brightness of the input image; a selector; a difference calculation unit that calculates the difference between the average brightness values; a duty cycle calculation unit that determines the duty cycle value based on the average brightness value or the difference; a register that stores a table for determining the duty cycle value; a duty cycle calculation unit that calculates the duty cycle value of an input PWM signal; and a cooperative processing unit that inputs multiple control signals representing the duty cycle value and determines the duty cycle value of the output PWM signal based on the duty cycle values ​​indicated by two control signals. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2012-220717 Summary of the Invention The problem the invention aims to solve

[0004] The image processing apparatus described in Patent Document 1 performs a prescribed brightness conversion process on the input image data to generate output image data and displays an image corresponding to the output image data. However, in this brightness conversion process, the detection signal detected by the illuminance sensor is not reflected. Therefore, when the image is displayed using light from a backlight that reflects the detection signal detected by the illuminance sensor, the image may have a different hue than the original, resulting in poor display quality.

[0005] The technology described in this specification is based on the circumstances described above and is intended to improve display quality. Solution for solving the problem

[0006] (1) The display device described in this specification includes: a display panel having a display surface; an image display unit that displays an image on the display surface based on grayscale information contained in image data supplied from an external supply source; an illumination device having multiple light sources that illuminate the display panel for display; a light source driving unit that drives the multiple light sources based on brightness information contained in the image data; an illuminance sensor that detects external light and outputs a detection signal corresponding to the detected amount of external light; and a control unit that corrects the brightness information based on the detection signal, controls the light source driving unit to drive the multiple light sources based on the corrected brightness information, and controls the image display unit to correct the grayscale information based on the detection signal and display the image based on the corrected grayscale information.

[0007] (2) Alternatively, the above-described display device may be configured such that, based on (1) above, the control unit controls the image display unit to display the image based on the corrected grayscale information for the first region included in the display surface and to display the image based on the uncorrected grayscale information for the second region other than the first region, and controls the light source driving unit to drive the first light source among the plurality of light sources that overlaps with the first region based on the corrected brightness information and to drive the second light source other than the first light source based on the uncorrected brightness information.

[0008] (3) Alternatively, the above-described display device may be based on (1) or (2) above, wherein the control unit has: a correction unit that corrects the brightness information and the gray level information; a drive signal generation unit that generates a drive signal for driving the light source based on the brightness information corrected by the correction unit and outputs the drive signal to the light source driving unit; and an image signal generation unit that generates an image signal for displaying the image on the display surface based on the gray level information corrected by the correction unit and outputs the image signal to the image display unit.

[0009] (4) Alternatively, the above-mentioned display device may also be, based on any one of (1) to (3) above, wherein the control unit has a memory that stores a first data table and a second data table, wherein the first data table contains multiple correction coefficients related to the brightness information and multiple detection signals, and the second data table contains multiple image data, multiple grayscale information and multiple brightness information, wherein the first data table binds the correction coefficients to the detection signals, and wherein the second data table binds the grayscale information and the brightness information to the image data, and wherein the image data contains the hue H and chromaticity H of the HSL color space. The brightness information is consistent with the brightness L. The control unit extracts the correction coefficient bound to the detection signal output from the illuminance sensor by referring to the first data table, corrects the brightness information by multiplying the extracted correction coefficient by the brightness information, and extracts the image data containing the hue H and chroma S contained in the image data supplied from an external supply source, and the brightness L consistent with the corrected brightness information as the corrected image data by referring to the second data table. The gray level information bound to the corrected image data is extracted as the corrected gray level information. Invention Effects

[0010] The technology described in this specification can improve display quality. Attached Figure Description

[0011] Figure 1 This is a schematic side view of the liquid crystal display device according to Embodiment 1. Figure 2 This is a cross-sectional view showing the liquid crystal panel and backlight device constituting the liquid crystal display device according to Embodiment 1. Figure 3 This is a top view of the LED substrate included in the backlight device according to Embodiment 1. Figure 4 This is a top view showing the pixel arrangement of the liquid crystal panel according to Embodiment 1. Figure 5 This is a top view showing the relationship between the dimming area and the LEDs in the display area of ​​the liquid crystal panel according to Embodiment 1. Figure 6 This is a top view showing the unit pixels included in the dimming area according to Embodiment 1. Figure 7 This is a block diagram illustrating the electrical configuration of the liquid crystal display device according to Embodiment 1. Figure 8This is a top view showing the relationship between the first and second regions included in the display area according to Embodiment 1 and the first and second LEDs. Figure 9 This is a diagram showing the first data table involved in Implementation 1. Figure 10 This is a diagram showing the second data table involved in Implementation 1. Figure 11 This is a flowchart illustrating the correction process performed by the control unit involved in Embodiment 1. Explanation of reference numerals in the attached figures 10…Liquid crystal display device (display device), 11…Liquid crystal panel (display panel), 11DS…Display surface, 12…Backlight device (illumination device), 13…Driver (image display unit), 15…LED (light source), 15α…First LED (first light source), 15β…Second LED (second light source), 19…LED driving circuit (light source driving unit), 30…Control unit, 33…Correction unit, 34…Memory, 35…Image signal generation unit, 36…Drive signal generation unit, 50…Illuminance sensor, A1…First area, A2…Second area, DT1…First data table, DT2…Second data table. Detailed Implementation

[0012] <Implementation Method 1> pass Figures 1 to 11 Embodiment 1 will be described. In this embodiment, a liquid crystal display device (display device) 10 is exemplified. Furthermore, the X-axis, Y-axis, and Z-axis are shown in parts of each figure, and the directions of each axis are depicted in the manner shown in each figure. Additionally, Figure 1 and Figure 2 The top side shown is designated as the front side, and the bottom side of the diagram is designated as the back side.

[0013] like Figure 1 As shown, the liquid crystal display device 10 includes: a liquid crystal panel (display panel) 11 that displays images; and a backlight device (illumination device) 12 disposed on the back side (rear side) of the liquid crystal panel 11, which illuminates the liquid crystal panel 11 with light for display. The liquid crystal panel 11 and the backlight device 12 are held by a predetermined holding member in an overlapping state.

[0014] like Figure 2As shown, the liquid crystal panel 11 is disposed on the front side (light-emitting side) opposite to the backlight device 12. The liquid crystal panel 11 has a pair of substrates 11A and 11B bonded together and a liquid crystal layer (not shown) sealed between the pair of substrates 11A and 11B. The front side of the pair of substrates 11A and 11B is the opposing substrate 11A, and the back side is the array substrate 11B. In addition, an alignment film is provided on each inner surface of the opposing substrate 11A and the array substrate 11B. Furthermore, a pair of polarizing plates 11C are respectively mounted on each outer surface of the opposing substrate 11A and the array substrate 11B.

[0015] like Figure 2 As shown, the central portion of the display surface 11DS of the liquid crystal panel 11 is designated as the display area AA for displaying images. The outer peripheral portion of the display surface 11DS of the liquid crystal panel 11 surrounding the display area AA is designated as the non-display area NAA, where no images are displayed. The array substrate 11B is larger than the opposing substrate 11A, and a portion of it forms a protrusion 11B1 that protrudes laterally relative to the opposing substrate 11A. The protrusion 11B1 is exposed and not covered by the opposing substrate 11A. The entire area of ​​the protrusion 11B1 is the non-display area NAA, where a driver (image display unit) 13 for supplying various signals and a flexible substrate 14 are mounted. The driver 13 includes an LSI chip with internal driving circuitry, which processes the various signals transmitted by the flexible substrate 14. The driver 13 supplies the processed signals (including image signals) to the liquid crystal panel 11. The driver 13 is mounted to the protrusion 11B1 of the array substrate 11B in a COG (Chip On Glass) manner. The flexible substrate 14 is configured such that multiple wiring patterns are formed on a substrate comprising an insulating and flexible synthetic resin material (e.g., polyimide resin). One end of the flexible substrate 14 is connected to a protrusion 11B1 of the array substrate 11B, and the other end is connected to the control substrate 18, which will be described later. Various signals supplied from the control substrate 18 are transmitted to the liquid crystal panel 11 via the flexible substrate 14, and after being processed by the driver 13 in the non-display area NAA, are output to the display area AA. Furthermore, the control substrate 18 is arranged to overlap with the backlight device 12 on the back side (the side opposite to the liquid crystal panel 11).

[0016] like Figure 2As shown, the backlight device 12 is configured as a so-called direct-lit type, where the main surface emitting light (light-emitting main surface) is opposite to the main surface of the back side of the liquid crystal panel 11. The central portion of the light-emitting main surface of the backlight device 12 that overlaps with the display area AA of the liquid crystal panel 11 when viewed from above is designated as the light-emitting area. The outer peripheral portion of the light-emitting main surface of the backlight device 12 that overlaps with the non-display area NAA of the liquid crystal panel 11 when viewed from above is designated as a non-light-emitting area that emits almost no light. The backlight device 12 includes at least an LED (Light Emitting Diode) 15 as a light source, an LED substrate (light source substrate) 16 on which multiple LEDs 15 are provided, and an optical component 17 that imparts optical effects to the light emitted from the LEDs 15.

[0017] like Figure 2 As shown, LED 15 is surface-mounted on LED substrate 16. LED 15 is configured as a top-emitting type, with its light-emitting surface 15A facing the side opposite to the LED substrate 16 (the front side, the side of optical member 17). The optical axis of LED 15 is aligned with the Z-axis direction. Here, "optical axis" refers to the axis that aligns with the direction of travel of the light with the highest luminous intensity (peak value) emitted by LED 15. In this embodiment, a white LED that emits white light is used as LED 15, exhibiting an overall white color.

[0018] like Figure 2 and Figure 3 As shown, the LED substrate 16 is plate-shaped or film-shaped, having a main surface parallel to the main surface of the liquid crystal panel 11. On the main surface of the LED substrate 16 facing the front, one of a pair of main surfaces, a plurality of LEDs 15 are mounted; this is called the mounting surface. The LEDs 15 are arranged in multiples at intervals along both the X-axis and Y-axis directions within the main surface of the LED substrate 16. The arrangement of the plurality of LEDs 15 can be matrix-like or staggered. The LED substrate 16 is connected to the control board 18 via connecting members such as FPC (Flexible Printed Circuit). Drive signals for driving the LEDs 15 are supplied to the LED substrate 16 from the control board 18 via the connecting members.

[0019] like Figure 2 As shown, the optical component 17 is plate-shaped or sheet-shaped, having main surfaces parallel to the main surfaces of the liquid crystal panel 11 and the LED substrate 16. The optical component 17 is positioned relative to the LED 15 at a distance that is spaced apart to the side in the Z-axis direction. The optical component 17 has the function of imparting a predetermined optical effect to the light emitted from the LED 15 and directing it towards the liquid crystal panel 11. The optical component 17... Figure 2Three optical components are arranged in a stacked manner. Each of the three optical components 17 includes a diffuser plate, a prism sheet, and a diffuser plate. The diffuser plate and diffuser plate function to diffuse and expel incident light. The prism sheet function to focus and expel incident light.

[0020] Next, use Figure 4 The configuration of the display area AA in the array substrate 11B constituting the liquid crystal panel 11 will be described. On the inner surface side of the display area AA of the array substrate 11B, as... Figure 4 As shown, at least TFTs (transistors, switching elements) 20 and pixel electrodes 21 are provided. Multiple TFTs 20 and multiple pixel electrodes 21 are arranged in a matrix (row-column) configuration with open intervals along the X-axis and Y-axis directions. Around these TFTs 20 and pixel electrodes 21, mutually orthogonal (crossing) gate wirings (scan wirings) 22 and source wirings (image wirings, signal wirings) 23 are arranged. Gate wirings 22 extend along the X-axis direction and are arranged with open intervals along the Y-axis direction. Scan signals are supplied to the multiple gate wirings 22 from the driver 13 or from a circuit section provided on the array substrate 11B. Source wirings 23 extend along the Y-axis direction and are arranged with open intervals along the X-axis direction. Image signals containing grayscale information are supplied to the multiple source wirings 23 from the driver 13. The TFT 20 has a gate electrode 20A connected to the gate wiring 22, a source electrode 20B connected to the source wiring 23, a drain electrode 20C connected to the pixel electrode 21, and a semiconductor portion 20D connected to the source electrode 20B and the drain electrode 20C and comprising a semiconductor material. The TFT 20 is driven based on a scan signal supplied from the gate wiring 22 to the gate electrode 20A. This scan signal contains a potential higher than the threshold voltage of the TFT 20. This creates a channel region in the semiconductor portion 20D, allowing charge to move between the source electrode 20B and the drain electrode 20C via the channel region. Therefore, a potential related to the image signal supplied from the source wiring 23 to the source electrode 20B is supplied to the drain electrode 20C via the semiconductor portion 20D. As a result, the pixel electrode 21 is charged to a potential related to the image signal. The pixel electrode 21 is disposed in the region surrounded by the gate wiring 22 and the source wiring 23, and its top-view shape is, for example, a generally elongated rectangular shape. Furthermore, in the display area AA opposite to substrate 11A, a plurality of color filters are disposed at positions opposite to each pixel electrode 21 on the array substrate 11B side. The color filters and the opposite pixel electrodes 21 together constitute a unit pixel, which is described later as a display unit. In addition, on the innermost surface (uppermost layer) of the two substrates 11A and 11B that is in contact with the liquid crystal layer, alignment films (not shown) are formed for aligning the liquid crystal molecules contained in the liquid crystal layer.

[0021] Alternatively, a common electrode can be provided on the array substrate 11B, overlapping all the pixel electrodes 21 with an insulating film between them. The orientation state of the liquid crystal molecules contained in the liquid crystal layer can be controlled using the electric field generated between the common electrode and each pixel electrode 21. When a common electrode is provided on the array substrate 11B, the display mode of the liquid crystal panel 11 can be set to IPS (In-Plane Switching) mode or FFS (Fringe Field Switching) mode, etc. On the other hand, a counter electrode can be provided on the inner surface side of the opposing substrate 11A, overlapping all the pixel electrodes 21 with a liquid crystal layer or alignment film between them. The orientation state of the liquid crystal molecules contained in the liquid crystal layer can be controlled using the electric field generated between the counter electrode and each pixel electrode 21. When a counter electrode is provided on the opposing substrate 11A, the display mode of the liquid crystal panel 11 can be set to IPS mode, FFS mode, VA (Vertical Alignment) mode, or TN (Twisted Nematic) mode, etc.

[0022] In the liquid crystal display device 10 configured as described above, such as Figure 2 As shown, planar light emitted from the plurality of LEDs 15 provided in the backlight device 12 illuminates the main surface of the back side of the liquid crystal panel 11. In the liquid crystal panel 11, when scan signals are sequentially supplied to the plurality of gate lines 22, the plurality of TFTs 20 connected to each gate line 22 are sequentially driven. When image signals are sequentially supplied to the plurality of source lines 23 in sync with the timing of the scan signals supplied to each gate line 22, the pixel electrodes 21 connected to the driven TFTs 20 are charged to a potential related to the image signal. By controlling the orientation state of the liquid crystal molecules according to the electric field generated between each pixel electrode 21 and the common electrode or the opposite electrode, the amount of transmitted light of the liquid crystal panel 11 can be controlled per unit pixel. As a result, a predetermined image is displayed in the display area AA of the liquid crystal panel 11.

[0023] In the liquid crystal display device 10 according to this embodiment, so-called local dimming control is performed. Local dimming control refers to improving the contrast ratio of the displayed image by adjusting the light emission of the plurality of LEDs 15 provided in the backlight device 12 according to the brightness of the image displayed on the display area AA of the liquid crystal panel 11. Specifically, for example, when the image displayed on the display area AA of the liquid crystal panel 11 includes bright and dark areas, the light emission of the LEDs 15 that supply light to the bright areas is increased, and the light emission of the LEDs 15 that supply light to the dark areas is decreased or set to not emit light. When performing such local dimming control, such as Figure 5As shown, the display area AA is first divided into multiple dimming areas (segmented areas, divided areas) DA. Multiple dimming areas DA are arranged in rows and columns along the X-axis and Y-axis directions within the main surface of the liquid crystal panel 11. Each dimming area DA is illuminated by light from multiple LEDs 15 provided by the backlight device 12. In this embodiment, one dimming area DA is primarily illuminated by light from one LED 15. Specifically, although a dimming area DA can be illuminated by light from multiple LEDs 15, the proportion of light from one LED 15, which is specifically configured relative to the dimming area DA, is dominant in the amount of light illuminating the dimming area DA. Specifically, the dimming area DA is square when viewed from above, and light from one LED 15 located near its center primarily illuminates the dimming area DA. That is, the dimming area DA is configured to include the area overlapping with the LED 15 and its surrounding area. Thus, in this embodiment, multiple LEDs 15 correspond individually to multiple dimming regions DA, and local dimming control is achieved by controlling the unit pixels belonging to each dimming region DA and the driving of each LED 15 corresponding to each dimming region DA.

[0024] In the dimming area DA, such as Figure 5 and Figure 6 As shown, multiple unit pixels are configured. A detailed description of each unit pixel is provided. First, the color filters disposed in the display area AA opposite the substrate 11A are arranged in a repeating order of the three colors R (red), G (green), and B (blue) along the X-axis. Each color filter is a strip extending along the Y-axis. These three color filters, together with the pixel electrode 21, constitute the red pixel RPX, green pixel GPX, and blue pixel BPX as unit pixels. Furthermore, in... Figure 6 In this design, the color represented by each unit pixel is denoted by the letters "R", "G", and "B". The display pixel DPX, composed of three unit pixels—red (RPX), green (GPX), and blue (BPX)—is capable of displaying a specified grayscale level of color. In the dimming area DA, multiple display pixels DPX are arranged in rows and columns along both the X and Y axes. Furthermore, in the display area AA opposite the substrate 11A, a light-blocking portion (black matrix) is provided to prevent color mixing, separating each color filter.

[0025] Next, use Figure 7 The electrical configuration of the liquid crystal display device 10 will be explained. For example... Figure 7As shown, the liquid crystal display device 10 includes a control unit 30 for controlling the driving of the liquid crystal panel 11 and the backlight device 12, an interface unit 40, and an illuminance sensor 50. The interface unit 40 allows the user of the liquid crystal display device 10 to input desired information. The illuminance sensor 50 can detect external light present around the liquid crystal display device 10 and output a detection signal corresponding to the detected amount of external light. The control unit 30 can perform local dimming control based on the detection signal from the illuminance sensor 50. Furthermore, the user of the liquid crystal display device 10 can appropriately change or adjust various settings related to the local dimming control performed by the control unit 30 via the interface unit 40. In addition, the control unit 30 consists of… Figure 2 The control board 18 shown is equipped with this.

[0026] like Figure 7 As shown, the control unit 30 includes an image processing unit 31, a CPU 32, a correction unit 33, a memory 34, an image signal generation unit 35, and a drive signal generation unit 36. The image processing unit 31 processes image signals (image data) supplied from an external host system (external power source) and outputs the processed image signal to the correction unit 33 and the image signal generation unit 35. The processed image signal output from the image processing unit 31 includes display grayscale information, which is grayscale information related to the image actually displayed in the display area AA. The display grayscale information will be explained in detail later. The CPU 32 can control the operation of the correction unit 33. When a user inputs an instruction to the interface unit 40, the CPU 32 controls the operation of the correction unit 33 based on that instruction. Instructions input to the interface unit 40 include... Figure 8 As shown, for example, it could be that "local dimming control is performed on a specific area (hereinafter referred to as area 1 A1) within the display area AA, while local dimming control is not performed on the other areas (hereinafter referred to as area 2 A2)." More specifically, for example, when the liquid crystal display device 10 is used as an indicator in a passenger vehicle, the interface unit 40 designates area 1 A1 for displays important for safety (e.g., warning displays), and area 2 A2 for displays other than 1 A1 (e.g., displays of lower importance than area 1 A1). Figure 8 In the first region A1 and the second region A2 shown, Figure 5 Each of the dimming zones DA shown contains multiple dimming zones. In addition, the settings of such zones A1 and A2 can be specified not only through the interface section 40, but also preset as default settings during the manufacturing stage.

[0027] like Figure 7As shown, when the CPU 32 receives a detection signal output from the illuminance sensor 50, it controls the operation of the correction unit 33 based on the detection signal. Controlled by the CPU 32, the correction unit 33 can correct the processed image signal output from the image processing unit 31. Local dimming control is achieved through the correction of the image signal by the correction unit 33. When correcting the processed image signal, the correction unit 33 can utilize information stored in the memory 34. The specific correction process performed by the correction unit 33 will be described in detail later. The memory 34 stores... Figure 9 and Figure 10 The data tables DT1, DT2, etc., are shown. The contents of data tables DT1 and DT2 will be explained in detail later. The image signal generation unit 35 generates an image signal based on the instruction from the correction unit 33 and outputs it to a timing controller (not shown). The image signal is supplied to the driver 13 of the liquid crystal panel 11 by the timing controller at a predetermined time. The drive signal generation unit 36 ​​generates a drive signal for driving the LED 15 based on the instruction from the correction unit 33 and outputs it to the LED drive circuit (light source drive unit) 19 included in the backlight device 12. The drive signal generated by the drive signal generation unit 36 ​​is, for example, a PWM (Pulse Width Modulation) signal. The PWM signal includes an ON period (light-up period) and an OFF period (off period), controlling the light emission of the LED 15 in a manner corresponding to the light emission amount corresponding to the duty cycle as the ratio of the ON period to the OFF period. The LED drive circuit 19 drives each LED 15 based on the input drive signal, illuminating them in a manner that achieves a predetermined light emission amount.

[0028] use Figures 9 to 11 This will explain the specific calibration process performed by the control unit 30. For example... Figure 11 As shown, the CPU 32 determines whether a detection signal has been input from the illuminance sensor 50 (step S10). If the determination result of step S10 is "no", the process returns to step S10, and the CPU 32 determines again whether a detection signal has been input. If the determination result of step S10 is "yes", the CPU 32 refers to... Figure 9 The first data table DT1 of the memory 34 shown (step S11). Here, the first data table DT1 will be described. In the first data table DT1, as follows Figure 9 As shown, the detection signals DS1 to DSN and the correction coefficients C1 to CN associated with the detection signals DS1 to DSN are recorded. Furthermore, in Figure 9In the diagram, the numbers "1 to N" are marked at the end of each marker for the detection signals DS1 to DSN and the correction coefficients C1 to CN, but these represent the number of markers, where "N" is a natural number. Furthermore, the markers in the first data table DT1 are for convenience only; the data written into the actual first data table DT1 can be appropriately changed, except for the markers shown in the diagram. The values ​​of the correction coefficients C1 to CN are set to any one of "1", "a value less than 1", or "a value greater than 1". The correction coefficient with a value of "1" is associated with the detection signal output when the external light intensity detected by the illuminance sensor 50 is within a specified reference range. This reference range of external light intensity is envisioned as a range within which a sufficiently good image can be visually recognized when displayed on the liquid crystal panel 11, even without local dimming control. The correction coefficient with a value less than 1 is associated with the detection signal output when the external light intensity detected by the illuminance sensor 50 is below a specified reference range. The correction factor, which is a value greater than 1, is associated with the detection signal output when the amount of external light detected by the illuminance sensor 50 exceeds the specified reference range.

[0029] In step S11, as Figure 11 As shown, CPU32 reference Figure 9 The first data table DT1 shown causes the correction unit 33 to extract the correction coefficients associated with the input detection signal. Next, the CPU 32 refers to... Figure 10 The second data table DT2 of the memory 34 shown (step S12). Here, the second data table DT2 will be described. In the second data table DT2, as Figure 10As shown, the display contains grayscale information (R1, G1, B1) to (RN, GN, BN), brightness information Br1 to BrN, and display grayscale information (r1, g1, b1) to (rN, gN, bN) and (h1, s1, l1) to (hN, sN, lN). The display grayscale information (r1, g1, b1) to (rN, gN, bN) and (h1, s1, l1) to (hN, sN, lN) are the values ​​of the RGB and HSL color spaces in the image actually displayed on the LCD panel 11. In detail, the grayscale information (r1, g1, b1) to (rN, gN, bN) includes the following: "r" represents the grayscale value of red in the RGB color space of the image displayed on the LCD panel 11; "g" represents the grayscale value of green in the RGB color space of the image displayed on the LCD panel 11; and "b" represents the grayscale value of blue in the RGB color space of the image displayed on the LCD panel 11. The grayscale information (h1, s1, l1) to (hN, sN, lN) includes the following: "h" represents the hue (H) in the HSL color space of the image displayed on the LCD panel 11; "s" represents the saturation (S) in the HSL color space of the image displayed on the LCD panel 11; and "l" represents the lightness (L) in the HSL color space of the image displayed on the LCD panel 11. Figure 10 The "R, G, B" column in the grayscale information display means the RGB color space, and the "H, S, L" column means the HSL color space.

[0030] Figure 10 The grayscale information (R1, G1, B1) to (RN, GN, BN) shown are the grayscale values ​​of the image signals assigned to the unit pixels RPX, GPX, and BPX of each color in the liquid crystal panel 11 via the TFT 20 and source wiring 23. Specifically, in the grayscale information (R1, G1, B1) to (RN, GN, BN), "R" represents the grayscale value of the image signal assigned to the red pixel RPX, "G" represents the grayscale value of the image signal assigned to the green pixel GPX, and "B" represents the grayscale value of the image signal assigned to the blue pixel BPX. The brightness information Br1 to BrN are the brightness of each LED 15 in the backlight device 12. This is assumed to be consistent with the "l" in the display grayscale information (h1, s1, l1) to (hN, sN, lN), i.e., the brightness L of the HSL color space. Furthermore, in Figure 10In the diagram, the markers for grayscale information (R1, G1, B1) to (RN, GN, BN) and display grayscale information (r1, g1, b1) to (rN, gN, bN) and (h1, s1, l1) to (hN, sN, lN) are marked with numbers "1 to N". These numbers represent the number of markers, where "N" is a natural number. Specifically, for 8-bit grayscale, "N" becomes "256", resulting in approximately 16.77 million grayscale and display grayscale markers. Furthermore, the markers in Data Table DT2 are for convenience only; the actual data written to Data Table DT2 can be modified as needed, except for the markers shown in the diagram.

[0031] In step S12, as Figure 11 As shown, CPU 32 refers to the second data table DT2 and causes the correction unit 33 to multiply the brightness L contained in the grayscale information by a correction coefficient to calculate the corrected brightness information. For example, as Figure 8 As shown, when the first region A1 is specified through the previously described interface unit 40, although the CPU 32 causes the correction unit 33 to multiply the brightness L contained in the display grayscale information related to the image displayed in the first region A1 by a correction coefficient to calculate the corrected brightness information, the corrected brightness information is not calculated for the image displayed in the second region A2. Specifically, the original display grayscale information (processed image signal after processing by the image processing unit 31) in the first region A1 has grayscale values ​​of (15, 143, 58) in the RGB color space (R, G, B) and (140, 207, 79) in the HSL color space (H, S, L). When the correction coefficient is "2", the value of the corrected brightness information is "158", which is twice the value of brightness L (79). Furthermore, as Figure 10 As shown, the grayscale information bound to the original display grayscale information is set to (RNa, GNb, BNc).

[0032] After that, as Figure 11As shown, CPU 32 refers to the second data table DT2 and causes the correction unit 33 to extract display grayscale information including hue H, chroma S, and luminance L consistent with the corrected luminance information in the first region A1 (step S13). In the above example, display grayscale information with values ​​of (140, 207, 158) for each of the HSL color space (H, S, L) is extracted. Then, CPU 32 refers to the second data table DT2 and causes the correction unit 33 to extract grayscale information bound to the extracted display grayscale information in the first region A1 (step S14). In the above example, grayscale information (RNd, GNE, BNf) bound to display grayscale information with values ​​of (140, 207, 158) for each of the HSL color space (H, S, L) is extracted in the second data table DT2. Then, the CPU32 controls the correction unit 33 to cause the image signal generation unit 35 to generate an image signal based on the extracted gray level information, and causes the drive signal generation unit 36 ​​to generate a drive signal based on the corrected brightness information (step S15).

[0033] Specifically, such as Figure 8 As shown, the image signal generation unit 35 generates each image signal in such a manner that the gray level value of the image signal given to the red pixel RPX disposed in the first region A1 becomes "RNd" included in the corrected display gray level information, the gray level value of the image signal given to the green pixel GPX disposed in the first region A1 becomes "GNe" included in the corrected display gray level information, and the gray level value of the image signal given to the blue pixel BPX disposed in the first region A1 becomes "BNf" included in the corrected display gray level information. On the other hand, the image signal generation unit 35 generates each image signal in such a manner that the gray level value of the image signal given to the red pixel RPX disposed in the second region A2 becomes "RNa" contained in the original (uncorrected) display gray level information, the gray level value of the image signal given to the green pixel GPX disposed in the second region A2 becomes "GNb" contained in the original display gray level information, and the gray level value of the image signal given to the blue pixel BPX disposed in the second region A2 becomes "BNc" contained in the original display gray level information. Figure 8 As shown, the drive signal generation unit 36 ​​generates a PWM signal with its duty cycle adjusted to become corrected brightness information, which is then supplied as a drive signal to the first LED (first light source) 15α among the plurality of LEDs 15 that overlaps with the first region A1. On the other hand, the drive signal generation unit 36 ​​generates a PWM signal with the duty cycle of the brightness L contained in the original display grayscale information, i.e., the uncorrected brightness information, which is then supplied as a drive signal to the second LED (second light source) 15β among the plurality of LEDs 15 that overlaps with the second region A2.

[0034] Here, if, in the above example, the input image data is processed using a conventional luminance conversion method to generate the output image data, then the grayscale values ​​of the corrected display grayscale information in the RGB color space (R, G, B) become (25, 237, 96), and the values ​​of the HSL color space (H, S, L) become (144, 217, 130). That is, in conventional luminance conversion processing, both hue (H) and chroma (S) differ from the original display grayscale information (hue H is 140, chroma S is 207), resulting in a different hue in the actually displayed image and poor display quality. In this respect, according to this embodiment, both hue (H) and chroma (S) in the corrected display grayscale information are consistent with the original display grayscale information, so the hue in the actually displayed image becomes the original hue, thereby achieving high display quality.

[0035] As described above, the liquid crystal display device (display device) 10 of this embodiment includes: a liquid crystal panel (display panel) 11 having a display surface 11DS; a driver (image display unit) 13 that displays an image on the display surface 11DS based on grayscale information contained in display grayscale information (image data) supplied from an external supply source; a backlight device (illumination device) 12 having a plurality of LEDs (light sources) 15 that illuminates the liquid crystal panel 11 with light for display; an LED driving circuit (light source driving unit) 19 that drives the plurality of LEDs 15 based on brightness information contained in the display grayscale information; an illuminance sensor 50 that detects external light and outputs a detection signal corresponding to the detected amount of external light; and a control unit 30 that corrects the brightness information based on the detection signal, controls the LED driving circuit 19 to drive the plurality of LEDs 15 based on the corrected brightness information, and controls the driver 13 to correct the grayscale information based on the detection signal and display an image based on the corrected grayscale information.

[0036] When external light is detected by the illuminance sensor 50, the illuminance sensor 50 outputs a detection signal corresponding to the amount of external light detected. Based on the detection signal output from the illuminance sensor 50, the control unit 30 corrects the brightness information and grayscale information contained in the display grayscale information supplied from an external power source. The LED driving circuit 19, controlled by the control unit 30, drives the LED 15 based on the corrected brightness information. The driver 13, controlled by the control unit 30, displays an image on the display surface 11DS based on the corrected grayscale information. Thus, the amount of light emitted by the LED 15 driven by the LED driving circuit 19 and the image displayed on the display surface 11DS both reflect the detection signal detected by the illuminance sensor 50, so compared to the past, the actual display grayscale level in the image is closer to the original display grayscale level. Therefore, an improvement in display quality can be achieved.

[0037] Furthermore, the control unit 30 controls the driver 13 to display an image based on corrected grayscale information for the first region A1 included in the display surface 11DS, and to display an image based on uncorrected grayscale information for the second region A2 other than the first region A1. It also controls the LED driving circuit 19 to drive the first LED (first light source) 15α, which overlaps with the first region A1, based on corrected brightness information, and to drive the second LED (second light source) 15β, which is other than the first LED 15α, based on uncorrected brightness information. For example, if the display surface 11DS includes a region displaying an important image, this region is designated as the first region A1, and the region displaying an image with lower importance than the first region A1 is designated as the second region A2. In the first region A1, an image based on grayscale information corrected by the driver 13 is displayed, and the first LED 15α, which overlaps with the first region A1, is driven based on brightness information corrected by the LED driving circuit 19. Therefore, the detection signal detected by the illuminance sensor 50 is reflected in the image displayed in the first region A1, thus improving the visual recognition of important images. Furthermore, although the detection signal detected by the illuminance sensor 50 is not reflected in the image displayed in the second region A2, it is of lower importance compared to the image displayed in the first region A1, so it is not a significant issue.

[0038] Additionally, the control unit 30 includes: a correction unit 33 that corrects brightness information and grayscale information; a drive signal generation unit 36 ​​that generates a drive signal for driving the LED 15 based on the brightness information corrected by the correction unit 33 and outputs the drive signal to the LED drive circuit 19; and an image signal generation unit 35 that generates an image signal for displaying an image on the display surface 11DS based on the grayscale information corrected by the correction unit 33 and outputs the image signal to the driver 13. The correction unit 33 corrects the brightness information and grayscale information contained in the displayed grayscale information based on the detection signal output from the illuminance sensor 50. The drive signal generation unit 36 ​​generates a drive signal for driving the LED 15 based on the brightness information corrected by the correction unit 33 and outputs it to the LED drive circuit 19. The LED drive circuit 19 drives the LED 15 using the drive signal output from the drive signal generation unit 36. The image signal generation unit 35 generates an image signal for displaying an image on the display surface 11DS based on the grayscale information corrected by the correction unit 33 and outputs it to the driver 13. The driver 13 displays an image on the display surface 11DS using the image signal output from the image signal generation unit 35. Thus, by including a correction unit 33, a drive signal generation unit 36, and an image signal generation unit 35 in the control unit 30, the amount of light emitted by the LED 15 and the image displayed on the display surface 11DS can respectively reflect the detection signal detected by the illuminance sensor 50.

[0039] Additionally, the control unit 30 includes a memory 34, which stores a first data table DT1 and a second data table DT2. The first data table DT1 contains multiple correction coefficients and detection signals related to brightness information. The second data table DT2 contains multiple display grayscale information, grayscale level information, and brightness information. In the first data table DT1, correction coefficients are bound to the detection signals. In the second data table DT2, grayscale level information and brightness information are bound to the display grayscale level information. Furthermore, the display grayscale level information includes hue (H), chroma (S), and brightness (L) of the HSL color space. The brightness information is consistent with the luminance L. The control unit 30 extracts the correction coefficients associated with the detection signal output from the illuminance sensor 50 by referring to the first data table DT1. The luminance information is corrected by multiplying the extracted correction coefficients by the luminance information. Furthermore, by referring to the second data table DT2, the control unit extracts the display grayscale information, which includes the hue H and chroma S contained in the display grayscale information supplied from an external source, and the luminance L consistent with the corrected luminance information, as the corrected display grayscale information. The grayscale information associated with the corrected display grayscale information is also extracted as the corrected grayscale information. In this way, the control unit 30 can easily correct the luminance information and grayscale information by referring to the first data table DT1 and the second data table DT2 stored in the memory 34.

[0040] <Other Implementation Methods> The technology disclosed in this specification is not limited to the embodiments described above and in the accompanying drawings; for example, the following embodiments are also included within the scope of the technology.

[0041] (1) It can also correct gray level information based on the detection signal from the illuminance sensor 50 throughout the entire display area AA without performing local dimming control, and display the image based on the corrected gray level information.

[0042] (2) The specific size of LED15 when viewed from above or the spacing of its arrangement when viewed from above, except for Figure 3 The diagram can be modified as needed. Mini LEDs or micro LEDs can also be used as LED15.

[0043] (3) In addition Figure 5 In addition to the illustration, it can also be set to configure multiple LEDs 15 in one dimming zone DA.

[0044] (4) The arrangement of unit pixels, in addition to Figure 6 In addition to the illustrations, appropriate changes can also be made.

[0045] (5) Regarding the specific electrical configuration of the liquid crystal display device 10, except for Figure 7 In addition to the illustrations, appropriate changes can also be made.

[0046] (6) The specific ranges of region A1 and region A2, and the specific quantities of LED15α and LED15β, in addition to Figure 8 The diagram can be modified as needed. The specific number of dimming areas DA contained in the first area A1 or the second area A2 can be set arbitrarily. For example, it can be set so that the first area A1 contains only 1 dimming area DA.

[0047] (7) The specific contents recorded in data table DT1, in addition to Figure 9 In addition to the illustrations, appropriate changes can also be made.

[0048] (8) The specific contents recorded in data table DT2, in addition to Figure 10 In addition to the illustrations, appropriate changes can also be made.

[0049] (9) The specific processing sequence involved in the correction process performed by the correction unit 33, in addition to Figure 11 In addition to the illustrations, appropriate changes can also be made.

[0050] (10) The colors presented by a unit pixel may also include colors other than red, green and blue (such as yellow or colorless transparent).

[0051] (11) The driver 13 can also be mounted on the flexible substrate 14 in a COF (Chip On Film) manner.

[0052] (12) The top view shape of the liquid crystal panel 11 can be a long rectangle, a square, a circle, a semicircle, a long oval, an ellipse, or a trapezoid.

[0053] (13) The liquid crystal display device 10 may also be used for purposes other than vehicle-mounted applications.

Claims

1. A display device, characterized in that, have: Display panel, which has a display surface; An image display unit displays an image on the display surface based on grayscale information contained in image data supplied from an external supply source; A lighting device having multiple light sources illuminates the display panel with light for display purposes. A light source driving unit drives multiple light sources based on the brightness information contained in the image data; An illuminance sensor detects external light and outputs a detection signal corresponding to the amount of external light detected. as well as Control Department The control unit corrects the brightness information based on the detection signal, controls the light source driving unit to drive multiple light sources based on the corrected brightness information, and controls the image display unit to correct the grayscale information based on the detection signal and display the image based on the corrected grayscale information.

2. The display device according to claim 1, wherein, The control unit controls the image display unit to display the image based on the corrected grayscale information for a first region included in the display surface, and to display the image based on the uncorrected grayscale information for a second region other than the first region. The control unit controls the light source driving unit to drive the first light source that overlaps with the first region among the plurality of light sources based on the corrected brightness information, and to drive the second light source other than the first light source based on the uncorrected brightness information.

3. The display device according to claim 1 or claim 2, wherein, The control unit includes: a correction unit that corrects the brightness information and the grayscale information; and a drive signal generation unit that generates a drive signal for driving the light source based on the brightness information corrected by the correction unit and outputs the drive signal to the light source driving unit. And an image signal generation unit, which generates an image signal for displaying the image on the display surface based on the grayscale information corrected by the correction unit and outputs the image signal to the image display unit.

4. The display device according to claim 1 or claim 2, wherein, The control unit has a memory that stores a first data table and a second data table. In the first data table, multiple correction coefficients related to the brightness information and multiple detection signals are included. In the second data table, multiple images, multiple grayscale information, and multiple brightness information are included. In the first data table, the detection signal is associated with the correction coefficient. In the second data table, the image data is bound to the grayscale information and the brightness information, and the image data includes the hue (H), chroma (S), and brightness (L) of the HSL color space. The brightness information is consistent with the brightness (L). The control unit extracts the correction coefficients associated with the detection signal output from the illuminance sensor by referring to the first data table, corrects the luminance information by multiplying the extracted correction coefficients by the luminance information, and extracts the image data containing the hue H and chroma S of the image data supplied from an external source, as well as the luminance L that is consistent with the corrected luminance information, as the corrected image data by referring to the second data table, and extracts the grayscale information associated with the corrected image data as the corrected grayscale information.

Images