Display device and control method of display device

Abstract

To optimize luminance of a backlight by determining the luminance of the backlight considering a video displayed on a display area and a partial area.SOLUTION: A display device comprises: a display panel (11) that has a display area (A0); a backlight 12 that irradiates a plurality of partial areas (Ai) with light; and a control unit (16). The control unit acquires average gradation, gradation distribution, partial average gradation and partial gradation distribution, and determines luminance of a plurality of light emitting devices on the basis of the average gradation, the gradation distribution, a plurality of pieces of average gradation and a plurality of pieces of partial gradation distribution.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a display device and a method for controlling the display device.

Background Art

[0002] When a backlight is divided into a plurality of areas, a technique for determining the luminance for each area is known (see Patent Document 1). In this technique, an input image is divided into a plurality of areas, and the luminance value of the backlight corresponding to each area is calculated (see paragraph 0021 of Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, as a result of the inventors' studies, it has been found that in the above-described technique, the luminance of the backlight may not necessarily be appropriate for the entire input image.

[0005] One aspect of the present invention aims to realize a display device and a method for controlling the display device, which further optimize the luminance of the backlight by determining the luminance of the backlight in consideration of both the display area for displaying an image and the image displayed in a partial area within this display area.

Means for Solving the Problems

[0006] In order to solve the above problems, a display device according to an aspect of the present invention includes a display panel having a display area where an image is displayed, a backlight having a plurality of light emitters that irradiate light to each of a plurality of sub-areas set to divide the display area and can independently control the luminance, a driving unit that drives the display panel and the backlight based on an image signal, and a control unit. The control unit executes an acquisition process of acquiring an average gradation of the image signal, a gradation distribution of the image signal, a partial average gradation that is an average gradation of a signal component corresponding to each of the plurality of sub-areas of the image signal, and a partial gradation distribution that is a gradation distribution of the signal component, and a luminance determination process of determining the luminance of the plurality of light emitters based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions. The driving unit drives the display panel and the backlight based on the image signal and the luminance determined in the luminance determination process.

Advantages of the Invention

[0007] According to an aspect of the present invention, by determining the luminance of the backlight in consideration of both the display area for displaying an image and the image displayed in the sub-areas in this display area, it is possible to realize a display device that further optimizes the luminance of the backlight and a control method for the display device.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] 〔Embodiment 1〕 Hereinafter, an embodiment of the present invention will be described in detail. FIG. 1 is a block diagram showing a display device 10 according to Embodiment 1 of the present invention. The display device 10 includes a display panel 11, a backlight 12, a driving unit 13 (display panel driving unit 13a, backlight driving unit 13b), a video signal processing unit 14, a storage unit 15, and a control unit 16.

[0010] The display panel 11 is, for example, a non-emissive display device, and as an example, a liquid crystal display device. The display panel 11 has a display area A0 where an image is displayed. The display area A0 has a plurality of sub-areas Ai set to divide the display area A0. A plurality of pixels P with changing gradations (for example, transmittance) are arranged in the display area A0 and the sub-areas Ai.

[0011] The backlight 12 is a light-emitting device that irradiates light to the display area A0 of the display panel 11, for example, a light-emitting diode. The backlight 12 has a plurality of light emitters Bi that irradiate light to each of the plurality of sub-areas Ai of the display panel 11 and can independently control the luminance.

[0012] The drive unit 13 drives the display panel 11 and the backlight 12 (light emitter Bi) based on the video signal IS. More specifically, the drive unit 13 drives the display panel 11 and the backlight 12 by the display control signal DS and the light emission control signal BS that are converted from the video signal IS by the video signal processing unit 14. The drive unit 13 includes a display panel drive unit 13a and a backlight drive unit 13b.

[0013] The display panel drive unit 13a drives the display panel 11 based on the display control signal DS output from the video signal processing unit 14, and displays an image on the display area A0.

[0014] The backlight drive unit 13b drives the backlight 12 based on the light emission control signal BS output from the video signal processing unit 14, and causes the plurality of light emitters Bi to emit light with respective luminances Li.

[0015] The video signal processing unit 14 is controlled by the control unit 16 to convert the video signal IS into a display control signal DS and a light emission control signal BS, and controls the driving of the display panel 11 and the backlight 12.

[0016] The video signal processing unit 14 obtains from the video signal IS (a) the average gradation AP0 of the video signal IS, (b) the gradation distribution PH0 of the video signal IS, (c) the partial average gradation APi of the video signal IS, and (d) the partial gradation distribution PHi of the video signal IS.

[0017] The average gradation AP0 and the gradation distribution PH0 are the average gradation and the gradation distribution in the display area A0. In contrast, the partial average gradation APi and the partial gradation distribution PHi are the average gradation and the gradation distribution in each of the partial areas Ai. More specifically, they are as follows.

[0018] (a) The average gradation AP0 is the average of the gradations in the display area A0 of the video signal IS (average gradation), for example, the average gradation level APL. (b) The gradation distribution PH0 is the distribution of the gradations in the display area A0 of the video signal IS (gradation distribution), for example, the gradation histogram. (c) The partial average gradation APi is the average (average gradation) of the gradations of the signal components ISi corresponding to the plurality of partial regions Ai of the video signal IS. (d) The partial gradation distribution PHi is the distribution (gradation distribution) of the gradations of the signal components ISi corresponding to the plurality of partial regions Ai of the video signal IS.

[0019] The storage unit 15 stores the nominal values of the parameters (1) to (4) described later, which are used for the control in the control unit 16.

[0020] The control unit 16 executes the acquisition process S11 and the luminance determination process S12 described later, and controls the driving of the display panel 11 and the backlight 12 via the driving unit 13 (display panel driving unit 13a, backlight driving unit 13b).

[0021] FIG. 2 is a flowchart showing the control method S10 of the display device 10 according to Embodiment 1 of the present invention. The control method S10 includes an acquisition process S11, a luminance determination process S12, and a driving process S13.

[0022] A. Acquisition process S11 The control unit 16 acquires the average gradation AP0, the gradation distribution PH0, the partial average gradation APi, and the partial gradation distribution PHi (hereinafter referred to as "average gradation AP0, etc."). The control unit 16 can acquire the average gradation AP0, etc. from the video signal processing unit 14, for example.

[0023] B. Luminance determination process S12 The control unit 16 determines the luminance Li of each of the plurality of light emitters Bi based on the average gradation AP0, etc. The details will be described later.

[0024] C. Driving process S13 The driving unit 13 (display panel driving unit 13a and backlight driving unit 13b) drives the display panel 11 and the backlight 12 based on the video signal IS and the luminance Li determined in the luminance determination process S12.

[0025] FIG. 3 is a flowchart showing an example of the luminance determination process S12. In this example, the luminance determination process S12 includes a parameter determination process S121 and a luminance determination process S122.

[0026] (a) Parameter determination process S121 The control unit 16 determines at least one of the parameters (1) to (4) based on the average gradation AP0 or the like. Details of the parameters (1) to (4) will be described later.

[0027] (b) Luminance determination process S122 The control unit 16 determines the luminance Li of the plurality of light emitters Bi based on at least one of the parameters (1) to (4). Hereinafter, details of the parameters (1) to (4) will be described.

[0028] (1) Parameter (1) is a parameter representing the correspondence relationship between the gradation Px of the video signal IS and the luminance gradation Py of the plurality of light emitters Bi.

[0029] As an example of parameter (1), a backlight (hereinafter referred to as "BK") gamma curve Fγ can be cited. FIG. 4 is a diagram showing an example of the BK gamma curve Fγ. The BK gamma curve Fγ represents the correspondence relationship between the gradation Px of the video signal IS and the gradation Py of the light emission control signal BS for controlling the gradation of the luminance Li of the light emitter Bi.

[0030] The horizontal axis in FIG. 4 is the gradation Px of the video signal IS, and the vertical axis is the gradation Py of the light emission control signal BS (the gradation of the light emitter Bi, that is, the luminance Li). Here, both the gradations Px and Py are in the range of zero (black) to 255 (white) (8 bits), and the luminance increases according to the gradation.

[0031] The relationship between the gradation Px of the video signal IS and the gradation Py of the light emission control signal BS (BK gamma curve Fγ) can be expressed by the following formula (1). Py = N × (Px / N) (1 / γ) = Fγ(Px) … Formula (1) N: Number of gradations (an integer of 1 or more), here, 255 (8 bits) γ: The quantity (γ value) that defines the shape of the BK gamma curve Fγ

[0032] When "γ = 1", the BK gamma curve Fγ becomes a linear curve (Py = Fγ(Px) = Px). When "γ > 1", the BK gamma curve is convex upward, and for the gradation Px, the gradation Py, that is, the luminance Li of the light emitter Bi, increases. When "γ < 1", the BK gamma curve Fγ is convex downward (concave), and for the gradation Px, the gradation Py, that is, the luminance Li of the light emitter Bi, decreases.

[0033] As can be seen from the above, the γ value may be considered as parameter (1). That is, both the BK gamma curve and the γ value are examples of parameter (1). As follows, it is preferable to appropriately determine parameter (1) according to the video.

[0034] When the BK gamma curve Fγ is convex upward, the middle gradation part of the video becomes relatively bright, and it becomes difficult for the viewer to feel a halo. However, in this case, the low gradation part (dark part) becomes bright, and the video tends to look floating. For example, in a night view including a quay and a Ferris wheel, the lights of the quay and the Ferris wheel are easy to see, but the night view itself tends to look floating.

[0035] On the other hand, when the BK gamma curve Fγ is convex downward, the low gradation part (dark part) can be made darker. However, in this case, the middle gradation part also becomes darker to some extent. Also, the brightness difference between the high gradation part (bright part) and the low gradation part (dark part) becomes larger, and it becomes easier for the viewer to feel a halo. For example, in a night view including a quay and a Ferris wheel, the night view looks dark and sunken, but the Ferris wheel and the like are difficult to see.

[0036] (2) The parameter (2) is a parameter for defining the luminance Li of a plurality of light emitters Bi based on the partial average gradation APi, and a predetermined partial high gradation PGi greater than the partial average gradation APi in the partial gradation distribution PHi. It is a parameter representing the weight of the partial average gradation APi with respect to the predetermined partial high gradation PGi. As an example of the parameter (2), the following blend ratio β can be cited. Note that the partial high gradation PGi means a gradation greater than the partial average gradation APi and smaller than the partial maximum gradation PMi described later.

[0037] The luminance Li (luminance of the light emitter Bi) in the partial region Ai can be defined based on the following formula (2). Li = APi × β + PMi × (1 - β) … Formula (2) APi: Partial average gradation (average gradation in the partial region Ai) PMi: Partial maximum gradation (maximum gradation in the partial region Ai) β: Blend ratio (weight of the partial average gradation APi with respect to the partial maximum gradation PMi)

[0038] That is, in Formula (2), the luminance Li of the partial region Ai is defined by the mixture (blend) of the partial average gradation APi and the partial maximum gradation PMi in the partial region Ai. When the blend ratio β increases, the luminance Li of the partial region Ai decreases, and when the blend ratio β decreases, the luminance Li of the partial region Ai increases. This is because the blend ratio β represents the weight of the partial average gradation APi with respect to the partial maximum gradation PMi.

[0039] Here, in Formula (2), instead of the partial maximum gradation PMi, a predetermined partial high gradation PGi greater than the partial average gradation APi may be used. In this case, the blend ratio β is defined as the weight of the partial average gradation APi with respect to the predetermined partial high gradation PGi in the partial region Ai. As follows, it is preferable to appropriately determine the parameter (2) according to the video.

[0040] When the blending ratio β increases, the weight of the partial average gradation APi increases. Therefore, between partial regions Ai with different partial maximum gradations PMi, the brightness difference in the low gradation part (dark part) of the video becomes smaller, and the halos become less noticeable. However, in this case, the high gradation part (bright part) becomes slightly darker, reducing the brightness and impact of the video. For example, in a starry night sky, the night sky is dark, but the stars become relatively darker and harder to see.

[0041] On the other hand, when the blending ratio β decreases, the high gradation part (bright part) of the video becomes brighter, increasing the impact of the video. However, in this case, the brightness difference in the low gradation part (dark part) between partial regions Ai with different partial maximum gradations PMi becomes larger, and the halos become more noticeable. For example, in a starry night sky, the stars are bright and easy to see, but the night sky appears to float and is easier to see.

[0042] (3) Parameter (3) is a parameter for adjusting the brightness of a plurality of second partial regions A2j when at least one first partial region A1i having a brightness greater than the first reference brightness Ls1 and a plurality of second partial regions A2j having a brightness less than a second reference brightness Ls2 less than the first reference brightness Ls1 are adjacent to each other. As an example of parameter (3), the following blur ratio Br can be cited. As will be described later, the blur ratio Br is an index representing the degree of blur (the degree of brightness adjustment, the range of the partial region Ai for adjusting the brightness).

[0043] There may be a case where at least one first partial region A1i having a brightness L1i greater than the first reference brightness Ls1 and a plurality of second partial regions A2j having a brightness L2j less than a second reference brightness Ls2 less than the first reference brightness Ls1 are adjacent to each other. For example, a partial region A1i with a high brightness L1i may be surrounded by partial regions A2j with a low brightness L2j. At this time, if the difference between the brightness L1i of the partial region A1i and the brightness L2j of the surrounding partial region A2j is large, the halos become more noticeable. Therefore, by increasing the brightness L2j of the partial region A2j around the partial region A1i with a high brightness L1i, the video around the partial region A1i can be blurred (blur), making the halos less noticeable.

[0044] FIG. 5 is a diagram showing an example of the luminance distribution of the backlight 12, and luminance distributions 12a to 12c are shown. In the luminance distribution 12a, around the light emitter B1i (corresponding to the partial region A1i) with a high luminance L1i, eight light emitters B2j (corresponding to the partial region A2j) with a low luminance L2j, sixteen light emitters B3k (corresponding to the partial region A3k) with a low luminance L3k, and thirty-four light emitters B4l (corresponding to the partial region 4l) with a low luminance L4l are sequentially surrounding it. At this time, the luminance L1i of the light emitter B1i is very large. For example, assuming that the lighting rate RL is 100%, the luminances of the other light emitters B2j, B3k, and B4l are very small. For example, it is assumed that the lighting rate RL is close to 0%. Note that, as shown in the following formula (3), the lighting rate RL means the ratio of the luminance Li of the light emitter Bi to the maximum luminance Lmax when the light emitter Bi emits light at the maximum gradation (for example, 255) of the video signal IS. RL = (Li / Lmax) × 100... Formula (3)

[0045] As described above, the blur is a function of lighting the light emitter B2j (partial region A2j) adjacent to the light emitter B1i (partial region A1i) with a high luminance (lit) to expand the partial region Ai with a high luminance. For example, as shown in the luminance distribution 12b, eight light emitters B2j adjacent to the light emitter B1i with a high luminance are lit. Further, as shown in the luminance distribution 12c, in addition to the eight light emitters B2j adjacent to the light emitter B1i, the light emitters B3k adjacent to the outer periphery of the light emitter B2j may be lit.

[0046] The luminance L2j of the light emitter B2j can be adjusted as shown in the following formula (4). L2jc = L2j + (L1i - L2j) × Br1... Formula (4) L1i: Luminance of the light emitter B1i L2j: Luminance of the light emitter B2j before adjustment L2jc: Luminance of the light emitter B2j after adjustment Br1: Blur rate (0 ≤ Br1 ≤ 1), the ratio for adjusting the luminance of the light emitter B2j according to the difference in luminance before adjustment (L1i - L2j)

[0047] When 「Br1 = 0」, 「L2jc = L2j」, and the luminance of the light emitter B2j does not change before and after adjustment. That is, 「Br1 = 0」 substantially means that no adjustment is made by the blurring. When 「Br1 = 1」, 「L2jc = L1i」, and the luminance of the light emitter B2j after adjustment becomes equal to the luminance of the light emitter B1i. In addition, when the light emitter B1i emits light at the maximum luminance Lmax and the light emitter B2j is not emitting light (luminance L2j = 0), 「L2jc = L1i × Br1」 holds.

[0048] As shown in the luminance distribution 12c, the luminance L3k of the light emitter B3k may be adjusted. In this case, the luminance L3k of the light emitter B3k can be adjusted as shown in the following equation (5). L3kc = L3k + (L1i - L3k) × Br2 … Equation (5) L1i: Luminance of the light emitter B1i L3k: Luminance of the light emitter B3k before adjustment L3kc: Luminance of the light emitter B3k after adjustment Br2: Blur rate (1 ≤ Br2 ≤ Br1 ≤ 1), the ratio for adjusting the luminance of the light emitter B3k according to the difference in luminance before adjustment (L1i - L3k)

[0049] When 「Br2 = 0」, 「L3kc = L3k」, and the luminance of the light emitter B3k does not change before and after adjustment. That is, 「Br2 = 0」 substantially means that no adjustment of the light emitter B3k is made by the blurring. When 「Br2 = Br1 = 1」, 「L3kc = L1i」, and the luminances of the light emitters B3k and B2j after adjustment become equal to the luminance of the light emitter B1i. In addition, when the light emitter B1i emits light at the maximum luminance Lmax and the light emitter B3k is not emitting light (luminance L3k = 0), 「L3kc = Lmax × Br2」 holds.

[0050] As described above, the blurring rate Br (combining Br1 and Br2 as Br) is an index representing the degree of blurring (the degree of brightness adjustment and the range of the partial area Ai where the brightness is adjusted). Here, the brightness of the low-brightness partial areas A2j and A2k that doubly surround the high-brightness partial area A1i is adjusted. Generalizing this, the brightness of the partial area that n-fold surrounds the high-brightness partial area Ai may be adjusted (n: an integer of 1 or more). In this case, n blurring rates Br (Br1 to Brn) will be set. As follows, it is preferable to appropriately determine the parameter (3), for example, the blurring rate Br, according to the video.

[0051] When the blurring rate Br is increased, the halos become less noticeable. However, in this case, since the increase in the brightness of the area A2j around the high-brightness area A1i is large, the brightness difference between the areas A1i and A2j becomes small, and the brightness feeling and impact of the video are reduced. For example, in a night view including a balloon, the balloon becomes relatively bright, but the halos are more noticeable in the night sky near the balloon.

[0052] On the other hand, when the blurring rate Br is decreased, since the change in the brightness of the area A2j around the high-brightness area A1i is small, the brightness difference between the areas A1i and A2j is large, and the impact of the video is increased. However, in this case, the halos in the video become more noticeable. For example, in a night view including a balloon, the halos are less noticeable in the night sky near the balloon, but the night sky stands out and the balloon becomes darker.

[0053] (4) The parameter (4) defines the maximum gradation of the gradation operation range in the partial area Ai of the display panel 11, and is a parameter for adjusting the brightness Li of the plurality of light emitters Bi corresponding to this maximum gradation. As an example of the parameter (4), the following aperture ratio OP can be cited.

[0054] The display panel 11, for example, a liquid crystal display device, does not necessarily have a linear relationship between the applied voltage and the transmittance. That is, in the liquid crystal display device, up to a certain level of applied voltage, the transmittance changes relatively linearly with respect to the applied voltage. However, when the applied voltage exceeds a certain level, even if the applied voltage is increased, the change in transmittance becomes small and substantially does not change (saturation characteristic). As a countermeasure, it is possible to define the maximum gradation of the gradation operation range of the liquid crystal display device. That is, within the original gradation range P0 to Pm (for example, 0 to 255), by setting the range of P0 to Pmc (Pmc ≤ Pm) as the gradation range, it becomes possible to take countermeasures against the saturation characteristic of the liquid crystal display device (adjustment corresponding to the saturation characteristic). This adjustment (saturation countermeasure) can be expressed by the following formula (6).

[0055] Pic = P0+(Pi - P0)×OP Lic = Li / OP OP=(Pmc - P0) / (Pm - P0) … formula (6) OP: aperture ratio (0 < LL ≤ OP ≤ 1) LL: lower limit of the aperture ratio OP Pi: gradation of the liquid crystal display device before adjustment Pic: gradation of the liquid crystal display device after adjustment P0: minimum value of the gradation operation range of the liquid crystal display device (minimum gradation, for example, 0) Pm: maximum value of the gradation operation range of the liquid crystal display device before adjustment (maximum gradation, for example, 255) Pmc: maximum value of the gradation operation range of the liquid crystal display device after adjustment (Pmc ≤ Pm) Li: luminance of the light emitter Bi before adjustment Lic: luminance of the light emitter Bi after adjustment (Lic ≤ Lmax)

[0056] When "OP = 1", "Pic = Pi" and "Lic = Li", and the gradation of the liquid crystal display device and the luminance of the light emitter Bi do not change before and after adjustment. That is, "OP = 1" substantially means that no adjustment for saturation countermeasure is performed.

[0057] As shown in Equation (6), when the aperture ratio OP is decreased (strengthening the saturation countermeasure), the gradation operation range of the liquid crystal display device becomes narrow, and gradation operation within the linear range of the liquid crystal display device becomes possible. The narrowing of the gradation range in the liquid crystal display device ( "(Pic - P0)=(Pi - P0)×OP" ) is compensated by an increase in the luminance of the light emitter Bi ( "Lic = Li / OP" ). As follows, it is preferable to appropriately determine the parameter (4), for example, the aperture ratio OP, according to the video.

[0058] When the aperture ratio OP is increased (weakening the saturation countermeasure), the high gradation part (bright part) can be brightened, but due to the saturation characteristics in the high gradation, the contrast in the high gradation part (bright part) decreases and it becomes easy to look blurred (blooming). For example, characters that shine white in a night scene shine brightly, but it becomes difficult to see the outline of the characters.

[0059] On the other hand, when the aperture ratio OP is decreased (strengthening the saturation countermeasure), the high gradation part (bright part) becomes slightly darker overall, but the contrast becomes good and it becomes easy to see clearly. For example, the outline of characters that shine white in a night scene can be clearly seen, but the characters themselves become slightly darker.

[0060] B. Determination of Parameters (1) to (4) FIG. 6 is a flowchart showing an example of the parameter determination process S121. The parameter determination process S121 includes processes S121a to S121d for determining the parameters (1) to (4) respectively. Here, as an example, all of the parameters (1) to (4) are determined, but the parameter determination process S121 only needs to determine at least any one of the parameters (1) to (4).

[0061] (1) Determination of Parameter (1) FIG. 7 is a diagram showing an example of the BK gamma curve to be determined. The BK gamma curve Fγa is an example of the BK gamma curve Fγ that is convex upward with respect to the linear curve. The BK gamma curve Fγb is an example of the BK gamma curve Fγ that is convex downward with respect to the linear curve.

[0062] In the parameter determination process S121, the control unit 16 may determine parameter (1) based on the average gradation AP0. For example, parameter (1) can be determined as follows in (a) to (c) below.

[0063] (a) When the average gradation AP0 is greater than the first reference value APs1, the BK gamma curve is convex upward (BK gamma curve Fγa in FIG. 8, γ > 1). (2) When the average gradation AP0 is less than the second reference value APs2 (APs2 < APs1), the BK gamma curve is convex downward (BK gamma curve Fγb, γ < 1). (c) When neither (a) nor (b) above applies, the BK gamma curve is set to nominal (for example, a linear curve, γ = 1).

[0064] In the parameter determination process S121, the control unit 16 may determine parameter (1) based on the average gradation AP0, the ratio of gradations greater than the first reference gradation Ps11 in the gradation distribution PH0, and the ratio of gradations less than the second reference gradation Ps12 less than the first reference gradation Ps11. For example, parameter (1), for example, the BK gamma curve Fγ, can be determined as follows in (a) to (c) below.

[0065] (a) When the average gradation AP0 is greater than the reference value APs11 and the ratio of gradations greater than the first reference gradation Ps11 in the gradation distribution PH0 exceeds a predetermined ratio TH11, the γ value is made greater than 1. The middle gradations of bright images can be emphasized. (b) When the average gradation AP0 is less than the second reference gradation APs12 (APs12 < APs11) and the ratio of gradations less than the second reference gradation Ps12 in the gradation distribution PH0 exceeds a predetermined ratio TH12 (Ps12 < Ps11), the γ value is made less than 1. The black floating in dark images can be suppressed. (c) When neither (a) nor (b) above applies, the BK gamma curve is set to nominal (for example, a linear curve, γ = 1).

[0066] (2) Determination of parameter (2) In the parameter determination process S121, the control unit 16 may determine the parameter (2) based on the average gradation AP0, the ratio of gradations greater than the first partial reference gradation Ps21 in the partial gradation distribution PHi, and the ratio of gradations smaller than the second partial reference gradation Ps22 smaller than the first partial reference gradation Ps21. For example, the parameter (2), for example, the blend ratio β, can be determined as follows in (a) to (c) below.

[0067] (a) When the average gradation AP0 is greater than a predetermined value APs21 and the ratio of gradations smaller than the second partial reference gradation Ps22 in the partial gradation distribution PHi does not exceed a predetermined ratio TH21, the blend ratio β is made smaller than the nominal value. A bright and vivid video expression becomes possible. (b) When the average gradation AP0 is smaller than a predetermined value APs22 (APs22 < APs21) and the ratio of gradations greater than the first partial reference gradation Ps21 in the partial gradation distribution PHi does not exceed a predetermined ratio TH22 (Ps21 > Ps22), the blend ratio β is made larger than the nominal value. The halo effect in a dark scene can be suppressed. (c) When neither (a) nor (b) above applies, the blend ratio β is set to the nominal value.

[0068] (3) Determination of parameter (3) In the parameter determination process S121, the control unit 16 may determine the parameter (3) based on the average gradation AP0, the ratio of gradations greater than the third partial reference gradation Ps31 in the partial gradation distribution PHi, and the ratio of gradations smaller than the fourth partial reference gradation Ps32 smaller than the third partial reference gradation Ps31. For example, the parameter (3), for example, the blur ratio Br, can be determined as follows in (a) to (c) below.

[0069] (a) When the average gradation AP0 is greater than a predetermined value APs31 and the ratio of gradations smaller than the fourth partial reference gradation Ps32 in the partial gradation distribution PHi does not exceed a predetermined ratio TH31, the blur ratio Br is made smaller than the nominal value. A bright and vivid video expression becomes possible. (b) When the average gradation AP0 is smaller than a predetermined value APs32 (APs32 < APs31), and in the partial gradation distribution PHi, the ratio of gradations larger than the third partial reference gradation Ps31 does not exceed a predetermined ratio TH32 (As31 > As32), increase the blur rate Br to be larger than the nominal value. The halation feeling in a dark scene can be suppressed. (c) When neither of (a) and (b) above is satisfied, set the blur rate Br to the nominal value.

[0070] (4) Determination of parameter (4) In the parameter determination process S121, the control unit 16 may determine the parameter (4) based on the average gradation AP0 and the ratio of gradations larger than the fifth reference gradation Ps41 in the gradation distribution PH0. For example, as in the following (a) and (b), the parameter (4), for example, the aperture ratio OP, can be determined.

[0071] (a) When the average gradation AP0 is smaller than a predetermined value APs4, and in the partial gradation distribution PHi, the ratio of gradations larger than the fifth reference gradation Ps41 exceeds a predetermined ratio TH4, set the aperture ratio OP to be smaller than the nominal value. (b) When it is not the case of (a), set the aperture ratio OP to the nominal value.

[0072] C. Determination of luminance FIG. 8 is a flowchart showing an example of the luminance determination process S122 based on parameters (1) to (4). Here, as an example, the luminance Li regulation process S122a, the luminance Li adjustment process S122b, and the luminance Li adjustment process S122c are executed in sequence. However, only a part of the processes S122a to S122c may be executed, or the order of the processes may be changed. Hereinafter, the processes S122a to S122c will be described in sequence.

[0073] (1) Regulation of the luminance Li of a plurality of light emitters Bi based on the partial average gradation APi, the partial maximum gradation PMi, and parameters (1) and (2) (process S122a) In the luminance determination process S12, the control unit 16 may define the luminance Li of the plurality of light emitters Bi based on the partial average gradation APi, a predetermined partial high gradation, and the parameter (2).

[0074] For example, based on Equation (2), the luminance Li in the partial region Ai is defined. Li = APi × β + PMic × (1 - β) Li: Luminance of the defined light emitter Bi

[0075] In the luminance determination process S12, the control unit 16 may define the luminance Li of the plurality of light emitters Bi based on the partial average gradation APi, a predetermined partial high gradation PGi, and the parameters (1) and (2).

[0076] For example, based on the BK gamma curve Fγ and Equation (1), the partial average gradation APi and the partial maximum gradation PMi are converted. APic = Fγ(APi) PMic = Fγ(PMi) APi: Partial average gradation before conversion APic: Partial average gradation after conversion PMi: Partial high gradation before conversion PMic: Partial high gradation after conversion

[0077] Thereafter, the control unit 16 defines the luminance Li in the partial region Ai based on Equation (2). Lis = APic × β + PMic × (1 - β) Lis: Luminance Li of the defined light emitter Bi

[0078] (2) Adjustment of the luminance Li of the plurality of light emitters Bi based on at least one of the parameters (3) and (4) (processes S122b and 122c) In the luminance determination process S12, the control unit 16 may adjust the luminance Li of the defined plurality of light emitters Bi based on at least one of the parameters (3) and (4). Hereinafter, it will be described by dividing it into (a) and (b).

[0079] (a) Distribution of the luminance Li on the display area with the specified luminance Li, adjustment of the luminance Li of the plurality of light emitters Bi based on parameter (3) (process S122b) For example, in the luminance determination process S12, the control unit 16 extracts a combination of at least one first partial region A1i adjacent to each other and a plurality of second partial regions A2j based on the luminances Li of the plurality of specified light emitters Bi, and may increase the luminance in at least one of the plurality of second partial regions based on parameter (3). Since the adjustment of the luminance Li of the plurality of light emitters Bi based on parameter (3) has been described, this detailed description is omitted.

[0080] (b) Adjustment of the luminance Li of the plurality of light emitters Bi based on parameter (4) (process S122c) For example, in the luminance determination process S12, the control unit 16 reduces the maximum gradation of the gradation operation range in the plurality of partial regions Ai based on parameter (4), and may increase the luminance of the plurality of light emitters so as to correspond to the reduction of this maximum gradation. Since the adjustment of the luminance Li of the plurality of light emitters Bi based on parameter (4) has been described, this detailed description is omitted.

[0081] As described above, in the present embodiment, based on the average gradation AP0 or the like, the luminance Li of the plurality of light emitters Bi is determined, and based on the video signal IS and the determined luminance Li, the display panel 11 and the backlight 12 are driven. As a result, corresponding to the average gradation AL0 or the like, the distribution of the luminance Li of the backlight 12, and thus the suitability of the displayed video, is achieved.

[0082] 〔Embodiment 2〕 Embodiment 2 of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiment are denoted by the same reference numerals, and the description thereof will not be repeated. FIG. 9 is a block diagram showing the display device 10 according to Embodiment 2 of the present invention.

[0083] The display device 10 according to Embodiment 2 includes a viewing environment sensor 21. The viewing environment sensor 21 is a sensor that acquires the illuminance B representing the brightness of the viewing environment or the color temperature Tc of the viewing environment.

[0084] The control unit 16 acquires the illuminance B representing the brightness of the viewing environment or the color temperature Tc of the viewing environment from the viewing environment sensor 21, and determines at least one of the parameters (1) and (2) based on the illuminance B or the color temperature Tc.

[0085] The control unit 16 can determine at least one of the parameters (1) and (2) based on the illuminance B, for example, as follows (a) to (c).

[0086] (a) When the illuminance B is greater than a predetermined value B1 (for example, in a bright room), the γ value is increased and the blend ratio β is decreased compared to the nominal value. A video expression with sharpness becomes possible. (b) When the illuminance B is less than a predetermined value B2 (B2 < B1) (for example, in a dark room), the γ value is decreased and the blend ratio β is increased compared to the nominal value. A video expression with a subdued dark part becomes possible. (c) When neither of (a) and (b) applies, the γ value and the blend ratio β are set to the nominal values respectively.

[0087] The control unit 16 can determine at least one of the parameters (1) and (2) based on the color temperature Tc, for example, as follows (a) to (c).

[0088] (a) When the color temperature Tc of the viewing environment (for example, illumination light) is higher than a predetermined value Tc1, the γ value is increased and the blend ratio β is decreased compared to the nominal value. When the color temperature Tc of the illumination light is high, it is often the case that content with a high color temperature such as sports and variety shows is being viewed. In this case, a bright and sharp video expression is preferred. (b) When the color temperature Tc is lower than a predetermined value Tc2 (Tc2 < Tc1), the γ value is made smaller and the blend ratio β is made larger than the nominal values. When the color temperature Tc of the illumination light is low, it is often the case that content with a low color temperature such as movie content is being viewed. For this reason, a tightened video expression with a sunken dark part is required. (c) When neither of these (a) or (b) is the case, the γ value and the blend ratio β are set to the nominal values respectively.

[0089] In the present embodiment, by using the viewing environment sensor 21 to automatically acquire information on the viewing environment and changing the parameters (1) and (2), the parameters (1) and (2) can be adapted to the viewing environment.

[0090] [Embodiment 3] Embodiment 2 of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as the members described in the above embodiment are given the same reference numerals, and the description thereof will not be repeated. Since Embodiment 3 of the present invention has the same configuration as Embodiment 1 of the present invention, the illustration thereof is omitted.

[0091] In Embodiment 3, the control unit 16 acquires genre information representing the genre of the video, and determines at least one of the parameters (1) and (2) based on the genre information. For example, the video signal IS includes genre information, and the control unit 16 can acquire the genre information from the video signal IS.

[0092] The control unit 16 can determine at least one of the parameters (1) and (2) based on the genre information, for example, as follows (a) to (c).

[0093] (a) When the genre information is variety or sports, the γ value is made larger and the blend ratio β is made smaller than the nominal values. This is because in variety and sports, videos with sharpness are preferred. (b) When the genre information is drama or movie, the γ value is made smaller and the blend ratio β is made larger than the nominal values. This is because in drama and movie, tightened videos are preferred. (c) If it is neither (a) nor (b) above, the γ value and the blend ratio β are set to their nominal values respectively.

[0094] In this embodiment, genre information is automatically acquired, and at least one of the parameters (1) and (2) can be adapted to the genre by changing at least one of the parameters (1) and (2).

[0095] [Embodiment 4] Embodiment 4 of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and their explanations will not be repeated. FIG. 10 is a block diagram showing a display device 10 according to Embodiment 4 of the present invention.

[0096] The display device 10 according to Embodiment 4 includes an information input unit 22. The information input unit 22 is an interface that enables a viewer to input video mode information. The information input unit 22 is, for example, a receiving unit that receives information from a remote controller of the display device 10. The viewer can switch the AV position, for example, by pressing a key for switching the AV position on the remote controller of the display device 10.

[0097] The control unit 16 can acquire video mode information from the information input unit 22 and determine at least one of the parameters (1) and (2) based on this video mode information.

[0098] The control unit 16 determines at least one of the parameters (1) and (2) based on the genre information, for example, as follows in (a) and (b) below.

[0099] (a) When the video mode information (AV position) is dynamic, the γ value is increased and the blend ratio β is decreased compared to the nominal value. (b) When the genre information is a movie, the γ value is decreased and the blend ratio β is increased compared to the nominal value.

[0100] As described above, in this embodiment, when the viewer changes the AV position, at least one of the parameters (1) and (2) is changed in conjunction with this change, enabling optimal video expression.

[0101] 〔Embodiment 5〕 Embodiment 5 of the present invention will be described below. For the sake of convenience of explanation, members having the same functions as those described in the above embodiments are denoted by the same reference numerals, and their explanations will not be repeated. FIG. 11 is a block diagram showing the display device 10 according to Embodiment 4 of the present invention.

[0102] The display device 10 according to Embodiment 5 includes an information input unit 22 and a viewer information acquisition unit 23. The information input unit 22 functions as a setting unit capable of setting at least any one of the parameters (1) to (4) for each viewer. The viewer information acquisition unit 23 is an acquisition unit that acquires identification information for identifying the viewer, for example, a television camera (face authentication), a fingerprint sensor (fingerprint authentication). It functions as a setting unit capable of setting at least any one of the parameters (1) to (4) for each viewer.

[0103] The control unit 16 acquires, for example, identification information for identifying the viewer from the viewer information acquisition unit 23, and switches at least any one of the parameters (1) to (4) based on the identification information.

[0104] As described above, in this embodiment, the viewer appropriately sets at least any one of the parameters (1) to (4), and the control unit 16 acquires the identification information of the viewer, enabling optimal video expression according to the viewer.

[0105] 〔Example of Realization by Software〕 The functions of the display device (hereinafter referred to as the "device") can be realized by a program for causing a computer to function as the device, and by a program for causing a computer to function as each control block of the device (particularly each part included in the control unit 16).

[0106] In this case, as hardware for executing the above program, the above device includes a computer having at least one control device (e.g., a processor) and at least one storage device (e.g., a memory). By executing the above program with this control device and storage device, each function described in each of the above embodiments is realized.

[0107] The above program may be recorded on one or more computer-readable recording media, rather than temporarily. This recording medium may or may not be provided in the above device. In the latter case, the above program may be supplied to the above device via any wired or wireless transmission medium.

[0108] Also, part or all of the functions of the above control blocks can also be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the above control blocks is formed is also included in the scope of the present invention. In addition to this, for example, it is also possible to realize the functions of the above control blocks by a quantum computer.

[0109] 〔Summary〕 The display device according to Aspect 1 of the present invention includes a display panel having a display area on which an image is displayed, a plurality of light emitters that irradiate light to each of a plurality of sub-areas set so as to divide the display area and whose luminance can be independently controlled, a driving unit that drives the display panel and the backlight based on a video signal, and a control unit. The control unit executes an acquisition process of acquiring the average gradation of the video signal, the gradation distribution of the video signal, the partial average gradation that is the average gradation of the signal components corresponding to each of the plurality of sub-areas of the video signal, and the partial gradation distribution that is the gradation distribution of the signal components, and a luminance determination process of determining the luminance of the plurality of light emitters based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions. The driving unit is configured to drive the display panel and the backlight based on the video signal and the luminance determined in the luminance determination process.

[0110] In this way, by determining the luminance of the backlight in consideration of both the display area for displaying an image and the image displayed in the partial area within this display area, further optimization of the luminance of the backlight can be achieved.

[0111] In the display device according to Embodiment 2 of the present invention, in the above Embodiment 1, in the luminance determination process, the control unit determines at least any one of the following parameters (1) to (4) based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions: (1) a parameter representing the correspondence between the gradation of the video signal and the luminance gradations of the plurality of light emitters; (2) a parameter for defining the luminance of the plurality of light emitters based on the partial average gradation and, in the partial gradation distribution, a predetermined partial high gradation greater than the partial average gradation, the parameter representing the weight of the partial average gradation with respect to the predetermined partial high gradation; (3) a parameter for adjusting the luminance of the plurality of second partial areas when at least one first partial area having a luminance greater than a first reference luminance and the plurality of second partial areas having a luminance smaller than a second reference luminance smaller than the first reference luminance are adjacent to each other; (4) a parameter for defining the maximum gradation of the gradation operation range in the partial area of the display panel and, corresponding to this maximum gradation, adjusting the luminance of the plurality of light emitters. The luminance of the plurality of light emitters may be determined based on at least any one of the parameters (1) to (4). In this way, by determining at least any one of the parameters (1) to (4) based on the average gradation, the gradation distribution, the partial average gradation, and the partial gradation distribution, and determining the luminance of the backlight based on the determined parameter, further optimization of the luminance of the backlight can be achieved.

[0112] In the display device according to Embodiment 3 of the present invention, in the above Embodiment 2, the control unit may be configured to define the luminance of the plurality of light emitters based on the partial average gradation, the predetermined partial high gradation, and the parameter (2) in the luminance determination process. Thereby, by defining the luminance of the light emitters based on the partial average gradation, the predetermined partial high gradation, and the parameter (2), further optimization of the luminance of the backlight can be achieved.

[0113] In the display device according to Embodiment 4 of the present invention, in the above Embodiment 3, the control unit may be configured to define the luminance of the plurality of light emitters based on the partial average gradation, the predetermined partial high gradation, and the parameters (1) and (2) in the luminance determination process. Thereby, by defining the luminance of the light emitters based on the partial average gradation, the predetermined partial high gradation, and the parameters (1) and (2), further optimization of the luminance of the backlight can be achieved.

[0114] In the display device according to Embodiment 5 of the present invention, in the above Embodiment 3 or 4, the control unit may be configured to adjust the luminance of the plurality of defined light emitters based on at least one of the parameters (3) and (4) in the luminance determination process. Thereby, by adjusting the luminance of the defined light emitters based on at least one of the parameters (3) and (4), further optimization of the luminance of the backlight can be achieved.

[0115] In the display device according to Embodiment 6 of the present invention, in the above Embodiment 5, the control unit extracts a combination of at least one first partial region adjacent to each other and the plurality of second partial regions based on the luminance of the plurality of defined light emitters in the luminance determination process, and may be configured to increase the luminance in at least one of the plurality of second partial regions based on the parameter (3). Thereby, by increasing the luminance in at least one of the plurality of second partial regions based on the parameter (3), further optimization of the luminance of the backlight can be achieved.

[0116] In the display device according to aspect 7 of the present invention, in the above aspect 5 or 6, in the luminance determination process, the control unit may be configured to reduce the maximum gradation of the gradation operation range in the plurality of partial regions based on the parameter (4), and increase the luminance of the plurality of light emitters so as to correspond to the reduction of the maximum gradation. Thereby, based on the parameter (4), by reducing the maximum gradation of the gradation operation range in the partial region and increasing the luminance of the light emitter so as to correspond to the reduction of the maximum gradation, further optimization of the luminance of the backlight can be achieved.

[0117] In the display device according to aspect 8 of the present invention, in any of the above aspects 2 to 7, the control unit may be configured to determine the parameter (1) based on the average gradation in the luminance determination process. Thereby, by determining the parameter (1) based on the average gradation, further optimization of the luminance of the backlight can be achieved.

[0118] In the display device according to aspect 9 of the present invention, in the above aspect 8, in the luminance determination process, the control unit may be configured to determine the parameter (1) based on the average gradation, the ratio of gradations greater than the first reference gradation in the gradation distribution, and the ratio of gradations smaller than the second reference gradation smaller than the first reference gradation. Thereby, by determining the parameter (1) based on the average gradation, the ratio of gradations greater than the first reference gradation, and the ratio of gradations smaller than the second reference gradation in the gradation distribution, further optimization of the luminance of the backlight can be achieved.

[0119] In the display device according to Embodiment 10 of the present invention, in any of the above-described Embodiments 2 to 9, in the luminance determination process, the control unit may be configured to determine the parameter (2) based on the average gradation, the ratio of gradations greater than a first partial reference gradation, and the ratio of gradations smaller than a second partial reference gradation smaller than the first partial reference gradation in the partial gradation distribution. Thereby, by determining the parameter (2) based on the average gradation, the ratio of gradations greater than a first reference gradation, and the ratio of gradations smaller than a second reference gradation in the gradation distribution, further optimization of the luminance of the backlight can be achieved.

[0120] In the display device according to Embodiment 11 of the present invention, in any of the above-described Embodiments 2 to 10, in the luminance determination process, the control unit may be configured to determine the parameter (3) based on the average gradation, the ratio of gradations greater than a third partial reference gradation, and the ratio of gradations smaller than a fourth partial reference gradation smaller than the third partial reference gradation in the partial gradation distribution. Thereby, by determining the parameter (3) based on the average gradation, the ratio of gradations greater than a third partial reference gradation, and the ratio of gradations smaller than a third reference gradation in the partial gradation distribution, further optimization of the luminance of the backlight can be achieved.

[0121] In the display device according to Embodiment 12 of the present invention, in any of the above-described Embodiments 2 to 11, in the luminance determination process, the control unit may be configured to determine the parameter (4) based on the average gradation and the ratio of gradations greater than a third reference gradation in the gradation distribution. Thereby, by determining the parameter (4) based on the average gradation, the ratio of gradations greater than a third reference gradation, and the ratio of gradations smaller than a fourth reference gradation in the gradation distribution, further optimization of the luminance of the backlight can be achieved.

[0122] In the display device according to aspect 13 of the present invention, in any of the above aspects 2 to 12, the control unit may be configured to acquire the illuminance representing the brightness of the viewing environment or the color temperature of the viewing environment, and determine at least one of the parameters (1) and (2) based on the illuminance or the color temperature. Thereby, by determining at least one of the parameters (1) and (2) based on the illuminance or the color temperature, further optimization of the brightness of the backlight can be achieved.

[0123] In the display device according to aspect 14 of the present invention, in any of the above aspects 2 to 13, the control unit may be configured to acquire genre information representing the genre of the video, and determine at least one of the parameters (1) and (2) based on the genre information. Thereby, by determining at least one of the parameters (1) and (2) based on the genre information, further optimization of the brightness of the backlight can be achieved.

[0124] In the display device according to aspect 15 of the present invention, in any of the above aspects 2 to 14, the control unit may be configured to acquire video mode information, and determine at least one of the parameters (1) and (2) based on the video mode information. Thereby, by determining at least one of the parameters (1) and (2) based on the video mode information, further optimization of the brightness of the backlight can be achieved.

[0125] In the display device according to aspect 16 of the present invention, in any of the above aspects 2 to 15, it includes a setting unit capable of setting at least any one of the parameters (1) to (4) for each viewer, and the control unit may be configured to acquire identification information for identifying the viewer and switch at least any one of the parameters (1) to (4) based on the identification information. Thereby, further optimization of the brightness of the backlight according to the viewer can be achieved.

[0126] The control method of a display device according to Embodiment 17 of the present invention is a control method of a display device including a display panel having a display area where an image is displayed, and a backlight having a plurality of light emitters that irradiate light to each of a plurality of sub-areas set to divide the display area and can independently control luminance, the method including: an acquisition process of acquiring an average gradation of the video signal, a gradation distribution of the video signal, a partial average gradation which is an average gradation of signal components corresponding to each of the plurality of sub-areas of the video signal, and a partial gradation distribution which is a gradation distribution of the signal components; a luminance determination process of determining the luminance of the plurality of light emitters based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions; and a driving process of driving the display panel and the backlight based on the video signal and the luminance determined in the luminance determination process.

[0127] Thereby, at least any one of parameters (1) to (4) is determined based on the average gradation, the gradation distribution, the partial average gradation, and the partial gradation distribution, and the luminance of the backlight is determined based on the determined parameter, whereby further optimization of the luminance of the backlight can be achieved.

[0128] The display device according to each aspect of the present invention may be realized by a computer. In this case, a control program for a display device that realizes the display device by operating a computer as each part (software element) included in the display device, and a computer-readable recording medium on which the program is recorded also fall within the scope of the present invention.

[0129] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present invention. Furthermore, by combining the technical means disclosed in each embodiment, new technical features can be formed.

Explanation of Reference Numerals

[0130] 10 Display device 11 Display panel 12 Backlight 13 Driving unit 13a Display panel driving unit 13b Backlight driving unit 14 Video signal processing unit 15 Memory unit 16 Control unit 21 Viewing environment sensor 22 Information input unit 23 Viewer information acquisition unit IS Video signal DS Display control signal BS Light emission control signal Bi Light emitter Li Luminance A0 Display area Ai Sub - area AP0 Average gradation PH0 Gradation distribution APi Sub - average gradation PHi Sub - gradation distribution PMi Sub - maximum gradation Fγ BK gamma curve (an example of parameter (1)) β Blend ratio (an example of parameter (2)) Br Blur ratio (an example of parameter (3)) OP Aperture ratio (an example of parameter (4))

Claims

1. A display panel having a display area where an image is displayed, A backlight having a plurality of light emitters that irradiate light to each of a plurality of sub-areas set to divide the display area and can independently control the luminance, A drive unit that drives the display panel and the backlight based on an image signal, A control unit, comprising, The control unit, an average gradation of the image signal, a gradation distribution of the image signal, a partial average gradation which is an average gradation of signal components corresponding to each of the plurality of sub-areas of the image signal, and a partial gradation distribution which is a gradation distribution of the signal components, an acquisition process for acquiring, and a luminance determination process for determining the luminance of the plurality of light emitters based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions, The drive unit drives the display panel and the backlight based on the image signal and the luminance determined in the luminance determination process. A display device.

2. In the luminance determination process, the control unit, determines at least any one of the following parameters (1) to (4) based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions, (1) A parameter representing the correspondence between the gradation of the image signal and the luminance gradation of the plurality of light emitters (2) A parameter for defining the luminance of the plurality of light emitters based on the partial average gradation and a predetermined partial high gradation greater than the partial average gradation in the partial gradation distribution, and representing the weight of the partial average gradation with respect to the predetermined partial high gradation. Parameter (3) Parameters for adjusting the luminance of the plurality of second partial regions when at least one first partial region having a luminance greater than the first reference luminance and a plurality of second partial regions having a luminance smaller than a second reference luminance smaller than the first reference luminance are adjacent to each other. (4) Parameters for defining the maximum gradation of the gradation operation range in the partial region of the display panel and adjusting the luminance of the plurality of light emitters corresponding to this maximum gradation. The display device according to claim 1, wherein the luminance of the plurality of light emitters is determined based on at least any one of the parameters (1) to (4).

3. In the luminance determination process, the control unit The display device according to claim 2, wherein the luminance of the plurality of light emitters is defined based on the partial average gradation, the predetermined partial high gradation, and the parameter (2).

4. In the luminance determination process, the control unit The display device according to claim 3, wherein the luminance of the plurality of light emitters is defined based on the partial average gradation, the predetermined partial high gradation, and the parameters (1) and (2).

5. In the luminance determination process, the control unit The display device according to claim 3, wherein the luminance of the plurality of defined light emitters is adjusted based on at least one of the parameters (3) and (4).

6. In the luminance determination process, the control unit Based on the luminance of the plurality of defined light emitters, an extraction is made of a combination of the at least one first partial region and the plurality of second partial regions adjacent to each other, The display device according to claim 5, wherein the luminance of at least one of the plurality of second partial regions is increased based on the parameter (3).

7. In the luminance determination process, the control unit The display device according to claim 5, wherein based on the parameter (4), the maximum gradation of the gradation operation range in the plurality of partial regions is decreased, and the luminance of the plurality of light emitters is increased so as to correspond to the decrease in the maximum gradation.

8. In the luminance determination process, the control unit determines the parameter (1) based on the average gradation, the display device according to any one of claims 2 to 7.

9. In the luminance determination process, the control unit determines the parameter (1) based on the average gradation, the ratio of gradations greater than a first reference gradation, and the ratio of gradations smaller than a second reference gradation smaller than the first reference gradation in the gradation distribution, the display device according to claim 8.

10. In the luminance determination process, the control unit determines the parameter (2) based on the average gradation, the ratio of gradations greater than a first partial reference gradation, and the ratio of gradations smaller than a second partial reference gradation smaller than the first partial reference gradation in the partial gradation distribution, the display device according to any one of claims 2 to 7.

11. In the luminance determination process, the control unit determines the parameter (3) based on the average gradation, the ratio of gradations greater than a third partial reference gradation, and the ratio of gradations smaller than a fourth partial reference gradation smaller than the third partial reference gradation in the partial gradation distribution, the display device according to any one of claims 2 to 7.

12. In the luminance determination process, the control unit determines the parameter (4) based on the average gradation and the ratio of gradations greater than a third reference gradation in the gradation distribution, the display device according to any one of claims 2 to 7.

13. The control unit Obtain the illuminance representing the brightness of the viewing environment or the color temperature of the viewing environment, and determine at least one of the parameters (1) and (2) based on the illuminance or the color temperature. The display device according to any one of claims 2 to 7.

14. The control unit, obtains genre information representing the genre of the video, and determines at least one of the parameters (1) and (2) based on the genre information. The display device according to any one of claims 2 to 7.

15. The control unit, obtains video mode information, and determines at least one of the parameters (1) and (2) based on the video mode information. The display device according to any one of claims 2 to 7.

16. is provided with a setting unit capable of setting at least any one of the parameters (1) to (4) for each viewer, The control unit, obtains identification information for identifying a viewer, and switches at least any one of the parameters (1) to (4) based on the identification information. The display device according to any one of claims 2 to 7.

17. a display panel having a display area where the video is displayed, a backlight having a plurality of light emitters that irradiate light to each of a plurality of sub-areas set to divide the display area and can independently control the luminance, A control method for a display device, comprising: the average gradation of the video signal, the gradation distribution of the video signal, a partial average gradation that is the average gradation of signal components corresponding to each of the plurality of sub-areas of the video signal, and a partial gradation distribution that is the gradation distribution of the signal components, an acquisition process for acquiring, A luminance determination process for determining the luminance of the plurality of light emitters based on the average gradation, the gradation distribution, the plurality of partial average gradations, and the plurality of partial gradation distributions; A control method for a display device, including: a driving process for driving the display panel and the backlight based on the video signal and the luminance determined in the luminance determination process.

Images