WO2019203055A1

WO2019203055A1 - Display device

Info

Publication number: WO2019203055A1
Application number: PCT/JP2019/015405
Authority: WO
Inventors: 井上　尚人; 寺沼　修; 尚子後藤; 彩岡本
Original assignee: シャープ株式会社
Priority date: 2018-04-19
Filing date: 2019-04-09
Publication date: 2019-10-24

Abstract

The present invention extends the battery life of a display device in which local dimming driving is possible more effectively than the prior art. A display device (1) according to the present invention comprises a BL (82), battery (60), control device (10), and display panel (81). The display device (1) can be made to operate in (i) a first local dimming mode or (ii) a second local dimming mode in which the power consumption is different than in the first local dimming mode. An information acquisition unit (110) of the control device (10) acquires first information that is at least one from among (i) information about the battery (60) and (ii) information about the power consumption of the display device (1). A mode selection unit (120) of the control device (10) selects the first local dimming mode or second local dimming mode on the basis of the first information.

Description

Display device

The following disclosure relates to a display device capable of driving local dimming (hereinafter referred to as “LD”).

Patent Document 1 discloses a technique for power saving in a display device (eg, a mobile phone) including a backlight (hereinafter referred to as “BL”) and a display panel. Specifically, in the technique of Patent Document 1, the light emission intensity of a part of the BL is changed so as to respond to the movement (movement) of the mobile phone.

Japanese Patent Gazette “Special Table 2014-508434 Gazette”

However, as will be described later, the technique disclosed in Patent Document 1 is not sufficient for extending the battery life in a display device capable of LD driving. An object of one embodiment of the present disclosure is to achieve a longer battery life more effectively than a conventional display device capable of LD driving.

In order to solve the above problems, a display device according to one embodiment of the present disclosure is a display device including a backlight divided into a plurality of areas whose emission intensity can be changed independently of each other, and a display panel A battery that can be charged and that supplies power to the backlight, and a control device that controls the backlight, the display device comprising: (i) a first local dimming mode, or , (Ii) operable in a second local dimming mode, which is different in power consumption from the first local dimming mode, and the control device comprises (i) information on the battery and (ii) consumption of the display device An information acquisition unit that acquires first information that is at least one of information on power, and the first local dimmies based on the first information. Comprising a Gumodo or mode selector for selecting the second local dimming mode, the.

According to the display device according to one aspect of the present disclosure, in a display device capable of LD driving, it is possible to realize a longer battery life more effectively than in the past.

FIG. 3 is a block diagram illustrating a configuration of a main part of the display device of Embodiment 1. It is a figure explaining an example of a control area. FIG. 2 is a block diagram illustrating a configuration example of an information acquisition unit in the display device of FIG. (A) and (b) are diagrams for explaining the first to third LD modes, respectively. FIG. 10 is another diagram for explaining the first to third LD modes. (A) And (b) is a figure explaining the example of selection of LD mode according to the 1st information, respectively. 10 is a block diagram illustrating a configuration example of an information acquisition unit in a display device according to Embodiment 2. FIG. (A) And (b) is a figure explaining the example of selection of LD mode according to the 2nd information, respectively. 10 is a block diagram illustrating a configuration example of an information acquisition unit in a display device according to Embodiment 3. FIG. It is a figure explaining the example of selection of LD mode according to the 3rd information. (A) and (b) are diagrams for explaining the fourth to sixth LD modes, respectively. FIG. 10 is another diagram for explaining the fourth to sixth LD modes.

Embodiment 1
Hereinafter, the display device 1 of Embodiment 1 will be described. For convenience, members having the same functions as those described in the first embodiment will be denoted by the same reference numerals in the following embodiments, and the description thereof will not be repeated. In addition, explanations of matters similar to those of known techniques are omitted as appropriate.

(Outline of display device 1)
FIG. 1 is a block diagram illustrating a configuration of a main part of the display device 1. As described below, the display device 1 is configured to be capable of LD driving. Hereinafter, among the display modes of the display device 1, a mode in which LD driving is performed is generically referred to as an LD mode. The display device 1 is preset with a plurality of types of LD modes with different power consumption. In the following description, it is assumed that the display device 1 operates in the LD mode unless otherwise specified.

As an example, the display device 1 is a portable display device. An example of a portable display device is a wearable device such as an HMD (Head-Mounted Display). Alternatively, the display device 1 may be a smartphone. However, the display device 1 may be a stationary display device. In this case, the display device 1 may be a desktop PC (Personal Computer), for example. The display device 1 only needs to be battery-driven.

The display device 1 includes a control device 10, a battery 60, an input unit 70, a display unit 80, and a storage unit 90. The control device 10 comprehensively controls each part of the display device 1. The control device 10 includes an LD processing unit 11, a display panel driving unit 12, and a BL driving unit 13. The LD processing unit 11 performs various display controls in the LD mode. The LD processing unit 11 includes an information acquisition unit 110 and a mode selection unit 120. An example of processing of the control device 10 will be described later.

The battery 60 supplies power to each part of the display device 1. The battery 60 is a known secondary battery (eg, lithium ion battery) that can be repeatedly charged. The battery 60 can be electrically connected to a charging device 6000 provided outside the display device 1 (hereinafter simply connected). The charging device 6000 is a known device that can charge the battery 60. As an example, charging device 6000 is an AC (Alternative Current) adapter. In the following example, it is assumed that charging device 6000 is connected to an unillustrated external power source (eg, commercial power source). When the charging device 6000 and the battery 60 are connected, the charging device 6000 supplies power to the battery 60.

The input unit 70 receives user input operations (hereinafter referred to as user operations). In the example of FIG. 1, for convenience, the input unit 70 and the display unit 80 are provided as separate bodies. However, the input unit 70 and the display unit 80 may be provided as an integral member. For example, the input unit 70 and the display unit 80 can be integrated by using a touch panel.

The display unit 80 includes a display panel 81 and a BL 82. The display panel 81 is, for example, an LCD (Liquid Crystal Display, liquid crystal) panel. In the display panel 81, a plurality of pixels (display elements) are arranged in a matrix. In the display unit 80 (display panels 81 and BL82), a horizontal direction (left-right direction, column direction) and a vertical direction (up-down direction, row direction) are defined in advance. Hereinafter, the horizontal direction is indicated by the letter i and the vertical direction is indicated by the letter j (see FIG. 2 described later).

BL82 irradiates the display panel 81 with light (eg, white light). The BL 82 is disposed on the back side of the display panel 81 (on the side opposite to the display surface) so as to overlap the display panel 81. However, for convenience of explanation, the display panel 81 and the BL 82 do not overlap in FIG.

BL 82 includes a plurality of light sources 820. As an example, in the BL 82, light sources 820 are arranged in a matrix in p pieces in the horizontal direction and q pieces in the vertical direction. Accordingly, the BL 82 includes (p × q) light sources 820. p and q are natural numbers, respectively. At least one of p and q is 2 or more.

The light source 820 is, for example, an LED (Light Emitting Diode). An image can be formed by a plurality of pixels on the display surface (display area) of the display panel 81 by light emitted from the light source 820 to the display panel 81. That is, a predetermined image can be displayed in the display area.

(Example of control area of BL82)
The BL 82 is divided into a plurality of areas (control areas) whose emission intensity can be changed independently of each other. FIG. 2 is a diagram illustrating an example of the control area. In the example of FIG. 2, a case where the BL 82 is divided into nine control areas (Area (1, 1) to Area (3, 3)) is shown. Hereinafter, each of these control areas is also referred to as Area (i, j). In the example of FIG. 2, i and j are integers that satisfy 1 ≦ i ≦ 3 and 1 ≦ j ≦ 3, respectively. The example of FIG. 2 corresponds to the case of p = q = 3. As an example,
Area (1, 1): The upper left area of the nine control areas;
Area (2, 2): Central area among the nine control areas;
Area (3, 3): The lower right area among the nine control areas;
It is. 2, the positive direction of i is set to the right direction, and the positive direction of j is set to the downward direction.

FIG. 2 illustrates a direct type BL82. In FIG. 2, the solid line indicates the boundary of each pixel. Moreover, a broken line shows the boundary of each control area. In the display area of the display panel 81, 30 pixels are formed in each of the horizontal direction and the vertical direction. Nine partial display areas are defined by dividing the display area into three regions divided in the horizontal direction and the vertical direction. Each partial display area is a partial area of the display area in which 10 pixels are formed in the horizontal direction and the vertical direction. Each control area is associated with these partial display areas. The number of pixels in the display area (example: 30 × 30 = 900) and the number of divisions of BL82 (number of control areas) (example: 3 × 3 = 9) are merely examples. Other values may be used as appropriate for the number of pixels and the number of divisions.

The control area means an area (unit of partial area) in which the emission intensity can be changed independently of each other in BL82. In the example of FIG. 2, Area (i, j) is an area where one light source 820 can be individually driven. In this case, Area (i, j) includes one light source 820. As an example, the light source 820 is located at the center of Area (i, j). As described above, the BL 82 includes nine light sources 820. However, the arrangement and number of the light sources 820 are not limited to the above example. For example, Area (i, j) may include a plurality of light sources 820.

Note that the “emission intensity of the control area” means the average brightness of the control area or the peak brightness of the control area. The light emission intensity in the control area is controlled by controlling the light emission intensity of the light source 820 in the control area.

(Example of processing of control device 10)
FIG. 3 is a block diagram illustrating a configuration example of the information acquisition unit 110 in the LD processing unit 11. The information acquisition unit 110 includes a battery connection state detection unit 111, a battery remaining amount detection unit 112, and a brightness setting condition detection unit 113. In the information acquisition unit 110, the battery connection state detection unit 111, the battery remaining amount detection unit 112, and the brightness setting condition detection unit 113 may be collectively referred to as a first information acquisition unit (see FIG. 9 described later). reference). In the example of FIG. 3, the information acquisition unit 110 corresponds to a first information acquisition unit.

The information acquisition unit 110 (first information acquisition unit) acquires first information. The first information is at least one of (i) information related to the battery 60 and (ii) information related to power consumption of the display device 1. The mode selection unit 120 selects a predetermined one LD mode from a plurality of types (at least two types) of LD modes based on the first information.

Embodiment 1 exemplifies a case where three types of LD modes (hereinafter referred to as first to third LD modes) are preset in the display device 1. For convenience, the first LD mode is also expressed as “LD とも Mode 1” in the drawings. This also applies to the second LD mode and the like. The mode selection unit 120 selects one LD mode from the first to third LD modes based on the first information.

The display panel drive unit 12 drives the display panel 81 according to the LD mode selected by the mode selection unit 120. The BL drive unit 13 drives the BL 82 according to the LD mode. More specifically, the BL drive unit 13 drives the light sources 820 individually for each control area (Area (1, 1) to Area (3, 3)). Thus, the BL drive unit 13 can independently control the light emission intensity of each control area.

4 and 5 are diagrams for explaining the first LD mode to the third LD mode, respectively. FIG. 4A shows a graph illustrating an example of a relationship between ABL (Average Backlight Level) (horizontal axis) and peak luminance (vertical axis) in each LD mode. FIG. 4B shows a graph showing an example of the relationship between ABL (horizontal axis) and overall BL power (vertical axis) in each LD mode. FIG. 5 shows an example of each numerical value in the example of FIG. 4 as a table.

The peak luminance means a peak value of luminance in the display area of the display panel 81. The BL total power means the power consumption of the entire BL82. The overall BL power is an index of power consumption of the display device 1. ABL means the average value (average luminance level) of the brightness of BL82. On the other hand, the average value of the luminance in the display area of the display panel 81 is referred to as APL (Average Picture Level). APL generally corresponds to ABL. For this reason, the horizontal axis of the graph of FIG. 4 may be approximately read as APL.

As shown in FIG. 4A, in the first embodiment, the third LD mode has the highest peak luminance among the three types of LD modes. Therefore, the third LD mode may be referred to as a “high peak luminance” LD mode. In the third LD mode, the maximum value of peak luminance (1000 cd / m ² ) is obtained when ABL = 25% (see also FIG. 5). In the third LD mode, (i) when ABL is in the range from 0% to 25%, the peak luminance increases as ABL increases, and (ii) in the range from 25% to 100% ABL, the ABL increases. As a result, the peak luminance decreases.

As shown in FIG. 5, in the third LD mode, the set value (hereinafter simply referred to as “current”) of the current supplied to each of the light sources 820 among the three types of LD modes is the largest value (80 mA). Is set. For this reason, as shown in FIG. 4B, in the first embodiment, the third LD mode has the largest power consumption among the three types of LD modes. In the third LD mode, (i) When the ABL is in the range from 0% to 25%, the overall BL power increases as the ABL increases. (Ii) In the range where the ABL is from 25% to 100%, the entire BL is increased. The power takes a constant value (value when ABL = 25%).

In the first embodiment, the current is constant regardless of ABL. In the LD mode, the ABL is changed under a constant current by controlling each lighting period of the light source 820 by, for example, PWM (Pulse Width Modulation) control.

In the first embodiment, the second LD mode has the second highest peak luminance among the three types of LD modes. For this reason, the second LD mode may be referred to as a “medium peak luminance” LD mode. In the second LD mode, the maximum value of peak luminance (600 cd / m ² ) is obtained when ABL = 50%. In the second LD mode, (i) when the ABL is in the range of 0% to 50%, the peak luminance increases as the ABL increases, and (ii) in the range of the ABL from 50% to 100%, the ABL increases. As a result, the peak luminance decreases.

In the second LD mode, the current is set to the second largest value (40 mA) among the three types of LD modes. For this reason, in Embodiment 1, the second LD mode has the second largest power consumption among the three types of LD modes. In the second LD mode, (i) when the ABL is in the range from 0% to 50%, the overall BL power increases as the ABL increases, and (ii) when the ABL is in the range from 50% to 100%, the entire BL is increased. The electric power takes a constant value (value when ABL = 50%).

In the first embodiment, the first LD mode has the lowest peak luminance among the three types of LD modes. Therefore, the first LD mode may be referred to as a “low peak luminance” LD mode. In the first LD mode, the maximum peak luminance (400 cd / m ² ) is obtained when ABL = 100%. In the first LD mode, the peak luminance increases with an increase in ABL over a range of ABL from 0% to 100%.

In the first LD mode, the current is set to the smallest value (20 mA) among the three types of LD modes. For this reason, in the first embodiment, the first LD mode has the lowest power consumption among the three types of LD modes. In the first LD mode, the entire BL power increases as the ABL increases over a range of ABL from 0% to 100%.

However, it should be noted that the magnitude relationship of power consumption between the first to third LD modes in the first embodiment is merely an example. The first to third LD modes may be set as LD modes having different power consumption. The same applies to the fourth embodiment described later.

As described above, in the display device 1, the peak luminance and the power consumption are in a trade-off relationship. For this reason, from the viewpoint of extending the life of the battery 60 (power saving of the battery 60), an appropriate LD mode is selected according to at least one of (i) the state of the battery 60 and (ii) power consumption. It is preferable to do. Therefore, as described above, the display device 1 is configured so that the LD mode can be automatically selected according to the first information.

(Selection example of LD mode according to the first information)
FIG. 6 is a diagram illustrating an example of selecting an LD mode according to the first information. FIG. 6A shows an example of LD mode selection according to the state of the battery 60. Hereinafter, this example will be described. Note that the table indicating the correspondence relationship in FIG. 6A may be stored in the storage unit 90. This also applies to other examples thereafter.

(Selection of LD mode according to connection state of battery 60)
The battery connection state detection unit 111 detects the connection state between the battery 60 and the charging device 6000 (eg, AC adapter). The battery connection state detection unit 111 supplies connection state information indicating the connection state to the mode selection unit 120. The connection state information is an example of first information (more specifically, information related to the battery 60). The connection state information can be said to be one piece of information indicating the state of the battery 60.

When the battery 60 is connected to the charging device 6000, the charging rate (remaining battery amount) (hereinafter referred to as Br) of the battery 60 is maintained at a sufficiently high value (for example, 100%) for a long time. . For this reason, it is expected that Br does not decrease even if the power consumption of the display device 1 is large. Therefore, when battery 60 is connected to charging device 6000, mode selection unit 120 selects the third LD mode (the LD mode with the highest peak luminance and the highest power consumption) as the LD mode. According to the third LD mode, a particularly bright and vivid display screen can be presented to the user of the display device 1.

(Selection of LD mode according to battery level)
The battery remaining amount detection unit 112 detects Br. The remaining battery level detection unit 112 supplies the charging rate information indicating the value of Br to the mode selection unit 120. The charging rate information is another example of the first information (more specifically, information related to the battery 60). The charging rate information is also one of information indicating the state of the battery 60.

In the first embodiment, two threshold values for Br (hereinafter referred to as Brth1 and Brth2) are set in advance. As long as the relationship of 0% <Brth1 <Brth2 <100% is satisfied, Brth1 and Brth2 may be arbitrarily set. In the following example:
• State of Br ≧ Brth2: The remaining battery level is large;
State of Brth1 <Br <Brth2: Battery remaining;
B ≦ Brth1: State of battery remaining low;
Each state regarding Br will be referred to as

When the remaining battery capacity is large, there is room for Br, so that it is allowed to increase the power consumption of the display device 1. Therefore, when the remaining battery level is large, the mode selection unit 120 selects the third LD mode as the LD mode.

On the other hand, when the battery is remaining, it is preferable to reduce the power consumption of the display device 1 to some extent in consideration of extending the life of the battery 60. Therefore, when the battery is remaining, the mode selection unit 120 selects the second LD mode (the LD mode with the second highest peak luminance and the second largest power consumption) as the LD mode. According to the second LD mode, it is possible to lengthen the time until Br reaches 0% compared to the third LD mode. That is, the life of the battery 60 can be extended. It can be said that the second LD mode is an LD mode in which the improvement of the quality of the display screen and the extension of the life of the battery 60 are compatible. Thus, the second LD mode is an intermediate LD mode between the above-described third LD mode and the first LD mode described below.

Furthermore, when the remaining battery level is low, it is preferable to give priority to extending the life of the battery 60 so that the operation of the display device 1 does not stop. Therefore, when the remaining battery level is low, the mode selection unit 120 selects the first LD mode (the LD mode with the lowest peak luminance and the lowest power consumption) as the LD mode. The first LD mode is most suitable for extending the life of the battery 60 among the three LD modes described above. As described above, the mode selection unit 120 selects the LD mode so that the power consumption becomes smaller as Br becomes smaller.

(Selection of LD mode according to the brightness of the screen setting of the display panel 81)
FIG. 6B shows an example of LD mode selection according to the brightness setting condition of the display panel 81 (brightness of screen setting). Hereinafter, this example will be described. The brightness setting condition detection unit 113 detects the brightness of the screen setting. The brightness setting condition detection unit 113 supplies the mode selection unit 120 with brightness setting condition information indicating the brightness value (hereinafter, L) of the screen setting. The brightness setting condition information is yet another example of the first information. The brightness setting condition information is an example of information regarding power consumption of the display device 1. This is because the power consumption of the display device 1 can depend on the size of L.

In the first embodiment, two threshold values for L (hereinafter, Lth1 and Lth2) are set in advance. As long as the relationship of Lth1 <Lth2 is satisfied, Lth1 and Lth2 may be set arbitrarily. In the following example:
・ L ≧ Lth2 state: High screen setting brightness;
Lth1 <L <Lth2 state: Screen setting brightness;
L ≦ Lth1 state: screen setting brightness small;
Each state regarding L is referred to as

When the screen setting brightness is large, even if the maximum value of the peak luminance is small, it is expected that the visibility of the user will not decrease so much. Therefore, when the screen setting brightness is large, the mode selection unit 120 selects the first LD mode as the LD mode. As an example, when displaying an image on the display panel 81 under a large ABL (eg, in a state of ABL≈100%), the first LD mode is selected. Thus, when the screen setting brightness is large, the display device 1 can be operated so as to be particularly suitable for extending the life of the battery 60.

On the other hand, when the brightness is set on the screen, it is preferable to set the maximum value of the peak luminance to a certain extent in order to prevent the user's visibility from decreasing. Therefore, when the screen setting brightness is being set, the mode selection unit 120 selects the second LD mode as the LD mode. As an example, when an image is displayed on the display panel 81 under a moderate ABL (eg, in a state where ABL≈50%), the second LD mode is selected. Thus, in the case of the screen setting brightness, the display device 1 can be operated so as to achieve both improvement of the visibility of the user and the extension of the life of the battery 60.

Further, when the screen setting brightness is small, it is preferable to set the maximum value of the peak luminance sufficiently large in order to prevent the user's visibility from being lowered. Therefore, when the screen setting brightness is small, the mode selection unit 120 selects the third LD mode as the LD mode. As an example, when an image is displayed on the display panel 81 under a small ABL (eg, in a state where ABL≈25%), the third LD mode is selected. Thus, when the screen setting brightness is small, the display device 1 can be operated so as to be particularly suitable for improving the visibility of the user. As described above, the mode selection unit 120 selects the LD mode so that the power consumption decreases as L increases.

(effect)
According to the display device 1, an LD mode corresponding to the first information can be selected. That is, an appropriate LD mode can be selected according to at least one of (i) the state of the battery 60 and (ii) power consumption. Therefore, the life of the battery 60 can be extended in a display device capable of LD driving.

On the other hand, in the past (for example, Patent Document 1), the idea of “automatically selecting (switching) the LD mode” has not been considered at all. For example, Patent Document 1 does not mention the point that the display device is LD-driven in the first place.

Furthermore, the conventional LD technology is mainly applied to a display device that is not driven by the battery 60 (a display device that is always connected to an external power source). For this reason, the concept of “selecting the conditions for LD driving so as to be suitable for extending the life of the battery 60” has not been considered in the past.

The display device 1 was newly conceived by the inventors of the present application based on a new idea of “selecting an appropriate LD mode in consideration of the trade-off relationship between peak luminance and power consumption”. . For this reason, the display device 1 is particularly suitable for a battery-driven display device (for example, a portable display device).

[Embodiment 2]
FIG. 7 is a block diagram illustrating a configuration example of the information acquisition unit 210 in the display device 2 according to the second embodiment. Unlike the information acquisition unit 110, the information acquisition unit 210 further includes a refresh rate detection unit 211 and an elapsed time detection unit 212. The refresh rate is also referred to as a screen frequency or an image frequency. The refresh rate detection unit 211 and the elapsed time detection unit 212 may be collectively referred to as a second information acquisition unit. Thus, the information acquisition unit 210 further includes a second information acquisition unit in addition to the first information acquisition unit.

The second information acquisition unit acquires second information. The second information is information relating to the refresh rate (hereinafter referred to as f) of the display panel 81. In the second embodiment, the mode selection unit 120 selects a predetermined one LD mode from a plurality of types of LD modes based further on the second information. According to the display device 2, the LD mode can be selected further according to the second information, which contributes to the longer life of the battery 60 more effectively.

(Selection example of LD mode according to f)
FIG. 8 is a diagram for explaining an example of selecting an LD mode according to the second information. FIG. 8A shows an example of LD mode selection according to f. The refresh rate detection unit 211 detects f. f may be set by the control device 10. As an example, the control device 10 may set (change) f in accordance with an image to be displayed on the display panel 81. The refresh rate detection unit 211 supplies refresh rate information indicating the value of f to the mode selection unit 120. The refresh rate information is an example of second information.

In the second embodiment, two threshold values for f (hereinafter, fth1 and fth2) are set in advance. As long as the relationship of 0 Hz <fth1 <fth2 is satisfied, fth1 and fth2 may be arbitrarily set. In the following example:
F ≥ fth2 state: high refresh rate;
Fth1 <f <fth2 state: during refresh rate;
F ≦ fth1 state: small refresh rate;
Each state relating to f is referred to as In the example of FIG. 8A, fth1 = 5 Hz and fth2 = 60 Hz are set.

When the refresh rate is high (for example, when f ≧ 60 Hz), it is considered that the screen is particularly intended to provide the user with a screen with excellent display quality. Therefore, it is considered that the user pays particular attention to the screen. Therefore, when the refresh rate is high, the mode selection unit 120 selects the third LD mode as the LD mode.

On the other hand, when the refresh rate is being performed (for example, when 5 Hz <f <60 Hz), the display quality of the screen may be lowered as compared with the case where the refresh rate is large. Therefore, when the refresh rate is being performed, the mode selection unit 120 selects the second LD mode as the LD mode. This contributes to extending the life of the battery 60 compared to when the refresh rate is high.

Furthermore, when the refresh rate is low (eg, when f <5 Hz), the display quality of the screen may be lowered as compared with the case during the refresh rate. Therefore, when the refresh rate is low, the mode selection unit 120 selects the first LD mode as the LD mode. This particularly contributes to extending the life of the battery 60. As described above, the mode selection unit 120 selects the LD mode so that the power consumption becomes smaller as f becomes smaller.

(Selection example of LD mode according to T)
FIG. 8B shows an example of selecting the LD mode according to the elapsed time (hereinafter, T) since the input unit 70 received a user operation. The elapsed time detection unit 212 detects T. The elapsed time detection unit 212 supplies elapsed time information indicating the value of T to the mode selection unit 120. The elapsed time information is another example of the second information. As an example, the control device 10 sets f according to T. More specifically, the control apparatus 10 sets f smaller as T becomes larger.

In the second embodiment, two thresholds for T (hereinafter, Tth1 and Tth2) are set in advance. As long as the relationship of 0s (seconds) <Tth1 <Tth2 is satisfied, Tth1 and Tth2 may be set arbitrarily. In the following example:
・ T ≦ Tth1 state: elapsed time is short;
Tth1 <T <Tth2 state: during elapsed time;
-State of T ≧ Tth2: Large elapsed time;
Each state relating to T is referred to as In the example of FIG. 8B, Tth1 = 10 s and Tth2 = 60 s (that is, 1 minute) are set.

When the elapsed time is short (for example, when T ≦ 10 s), only a short time has elapsed since the user operation (for example, mouse click or touch panel pressing), so the user is considered to pay particular attention to the display screen. . For this reason, it can be said that it is particularly preferable to improve the display quality of the screen. Therefore, when the elapsed time is short, the mode selection unit 120 selects the third LD mode as the LD mode.

On the other hand, when the elapsed time is in progress (eg, when 10 s <T <60 s), it is considered that the user is not paying attention to the screen as much as the elapsed time is small. Accordingly, the display quality of the screen may be lowered as compared with the case where the elapsed time is short. Therefore, when the elapsed time is in progress, the mode selection unit 120 selects the second LD mode as the LD mode.

Furthermore, when the elapsed time is large (for example, when T ≧ 60 s), the display quality of the screen may be lowered as compared with the case during the elapsed time. Therefore, when the elapsed time is long, the mode selection unit 120 selects the first LD mode as the LD mode. As described above, the mode selection unit 120 selects the LD mode so that the power consumption decreases as T increases.

(Supplement)
The control device 10 may set f according to the resolution of the image displayed on the display panel 81. Therefore, the information acquisition unit 210 may detect the resolution. In this case, the information acquisition unit 210 may supply resolution information indicating the resolution to the mode selection unit 120. The resolution information is yet another example of the second information. Therefore, the mode selection unit 120 may select the LD mode according to the resolution information.

[Embodiment 3]
FIG. 9 is a block diagram illustrating a configuration example of the information acquisition unit 310 of the display device 3 according to the third embodiment. Unlike the information acquisition unit 110, the information acquisition unit 310 further includes an application type determination unit 311 and a screen occupation rate detection unit 312. The application type determination unit 311 and the screen occupation rate detection unit 312 may be collectively referred to as a third information acquisition unit. Thus, the information acquisition unit 310 further includes a third information acquisition unit in addition to the first information acquisition unit.

In addition, “application” in this specification means “application software”. Further, a third information acquisition unit may be further added to the information acquisition unit 210. That is, the information acquisition unit according to an aspect of the present disclosure may include a first information acquisition unit, a second information acquisition unit, and a third information acquisition unit.

The third information acquisition unit acquires third information. The third information is information related to an application (hereinafter, “execution application”) being executed by the display device 3 (more specifically, the control device 10). In the third embodiment, the mode selection unit 120 selects a predetermined one LD mode from a plurality of types of LD modes further based on the third information. According to the display device 3, since the LD mode can be further selected according to the third information, it contributes to the extension of the life of the battery 60 more effectively.

FIG. 10 is a diagram for explaining an example of selecting the LD mode according to the third information. The application type determination unit 311 determines the type of execution application. The number of execution applications may be one or plural. The application type determination unit 311 supplies application type information indicating the type of execution application to the mode selection unit 120. The application type information is an example of third information.

The screen occupancy rate detection unit 312 detects the screen occupancy rate (hereinafter, Sr) of the execution application. Sr is the ratio of the area of the display screen of one execution application (hereinafter referred to as S1) to the area of the display area of the display panel 81 (hereinafter referred to as St). That is, Sr = S1 / St. In the following example, Sr is expressed in%. The screen occupancy rate detection unit 312 supplies occupancy rate information indicating the value of Sr to the mode selection unit 120. Occupancy rate information is another example of the third information.

(First selection example in Embodiment 3)
Consider a case where moving image content is displayed by a moving image viewing application in most or all of the display area. In such a case, it is considered that the user desires to view the display screen of the moving image viewing application with particularly high display quality. The video app is a typical example of an application that is required to display a screen under a small ABL.

Therefore, (i) the execution application includes a specific first application (eg, a video viewing application), and (ii) Sr of the first application is equal to or greater than a predetermined threshold (eg, Sr ≧ 70%) If so, the mode selection unit 120 selects the third LD mode as the LD mode. The first application may be any application suitable for screen display with a small ABL.

(Second selection example in Embodiment 3)
Consider a case in which display screens of a plurality of applications are mixedly displayed in the display area. In such a case, it can be said that the display quality may be lowered as compared with the case of the first selection example described above. That is, the screen display may be performed under an ABL larger than that in the first selection example described above.

Therefore, when (i) there are a plurality of execution applications and (ii) Sr of each execution application is equal to or less than a predetermined threshold (eg, Sr ≦ 50%), the mode selection unit 120 sets the LD mode as the LD mode. The second LD mode is selected.

(Third selection example in Embodiment 3)
Consider a case where a display screen of a text creation application (an example of an office suite application) is displayed over most or the entire display area. In many cases, the text creation application is used without the purpose of viewing images. For this reason, it is considered that the quality of the display screen does not have to be so high when using the text creation application. A text creation application is a typical example of an application that may perform screen display under a large ABL.

Therefore, (i) the execution application includes a specific second application (for example, a text creation application), and (ii) Sr of the second application is equal to or greater than a predetermined threshold (for example, Sr ≧ 70%) If so, the mode selection unit 120 selects the first LD mode as the LD mode. The second application may be any application suitable for screen display with a large ABL. The second app is an app different from the first app.

[Embodiment 4]
The plural types of LD modes are not limited to the first to third LD modes described above. In the fourth embodiment, the fourth to sixth LD modes are set as the LD mode of the display device. The fourth LD mode corresponds to the first LD mode, the fifth LD mode corresponds to the second LD mode, and the sixth LD mode corresponds to the third LD mode. The fourth to sixth LD modes may be applied to any of the display devices 1 to 3.
The fourth LD mode is the same mode as the first LD mode. However, for convenience of explanation, different mode numbers are given in the fourth embodiment. As described above, the fourth to sixth LD modes can be said to be other examples of the first to third LD modes.

11 and 12 are diagrams for explaining the fourth LD mode to the sixth LD mode, respectively. (A) and (b) of FIG. 11 are graphs corresponding to (a) and (b) of FIG. 5, respectively. FIG. 12 is a diagram including a table corresponding to FIG.

As shown in FIG. 12, in the fourth to sixth LD modes, the maximum value of the peak luminance is set to the same value (400 cd / m ² ). For this reason, in the fourth to sixth LD modes, the currents are all set to the same value (20 mA). Note that the value of 20 mA is selected as the minimum current value necessary to ensure the maximum value of peak luminance of 400 cd / m ² .

Thus, the fifth and sixth LD modes are different from the second and third LD modes with respect to the maximum peak luminance and the current value. However, as shown in FIG. 11A, the fifth LD mode is the same as the second LD mode in the tendency of the change in the peak luminance accompanying the increase in ABL. For this reason, also in the fifth LD mode, the maximum value of peak luminance is obtained when ABL = 50%. Similarly, the sixth LD mode is the same as the third LD mode in the tendency of the change in peak luminance accompanying the increase in BL. Therefore, even in the sixth LD mode, the maximum value of peak luminance is obtained when ABL = 25%.

For this reason, as shown in FIG. 11B, the sixth LD mode consumes less power than the third LD mode. Similarly, power consumption is lower in the fifth LD mode than in the second LD mode. Furthermore, in both the fifth and sixth LD modes, power consumption is lower than in the fourth LD mode. In particular, the sixth LD mode has the lowest power consumption among the above-described LD modes. The fifth LD mode has the second lowest power consumption among the LD modes described above. Therefore, according to the fourth embodiment, compared to the first to third embodiments, it contributes to the extension of the life of the battery 60 more effectively.

Currently, various standards relating to HDR (High Dynamic Range) have been proposed with the progress of LD technology. Many of these standards require a value of 400 cd / m ² or more as the maximum value of peak luminance. For example, in HDR 400, the maximum peak luminance is required to be at least 400 cd / m ² or more. The above-mentioned value of 400 cd / m ² is set so as to conform to HDR400. Therefore, any of the first to sixth LD modes is compatible with HDR400.

In HDR 600, the maximum peak luminance is required to be at least 600 cd / m ² or more. The above-described second LD mode is set to conform to HDR600. In HDR 1000, the maximum peak luminance is required to be at least 1000 cd / m ² or more. The third LD mode described above is set so as to conform to HDR1000.

[Embodiment 5]
The first to sixth LD modes may be used in combination. As described above, when the LD modes are arranged in descending order of power consumption, “third LD mode”, “second LD mode”, “first LD mode (fourth LD mode)”, “fifth LD mode”, “sixth LD mode”. It becomes order of "mode". Hereinafter, as an example, a case where the LD mode is selected according to the remaining battery level is illustrated. Although the description is omitted, the same applies to other selection examples.

In the fifth embodiment, unlike the first embodiment, two threshold values (hereinafter referred to as Brth1U and Brth2L) are set in advance for Br. As long as the relationship of 0% <Brth1 <Brth1U <Brth2L <Brth2 <100% is satisfied, Brth1U and Brth2L may be set arbitrarily. In the following example:
• State of Br ≧ Brth2: The remaining battery level is large;
State of Brth2L ≦ Br <Brth2: Battery level is slightly large;
State of Brth1U ≦ Br <Brth2L: battery remaining amount;
-State of Brth1 <B <Brth1U: Battery level is slightly small;
B ≦ Brth1: State of battery remaining low;
Each state regarding Br will be referred to as In this way, by increasing the number of thresholds for Br, more states related to Br may be defined than in the case of the first embodiment.

In this case, as an example, the mode selection unit 120
-When battery level is high: Select 3rd LD mode;
-When the battery level is slightly high: Select the second LD mode;
-When the battery is remaining: Select the first LD mode (fourth LD mode);
-When the battery level is slightly low: Select the 5th LD mode;
-When the remaining battery level is low: Select the 6th LD mode;
As described above, the LD mode may be selected according to the remaining battery level. Thus, by increasing the types of LD modes, it is possible to realize more various LD mode switching.

[Example of software implementation]
The control blocks (particularly the control device 10) of the display devices 1 to 3 may be realized by a logic circuit (hardware) formed in an integrated circuit (IC chip) or the like, or may be realized by software.

In the latter case, the display devices 1 to 3 are provided with a computer that executes instructions of a program that is software for realizing each function. The computer includes, for example, at least one processor (control device) and at least one computer-readable recording medium storing the program. In the computer, the processor reads the program from the recording medium and executes the program, thereby achieving the object of one aspect of the present disclosure. As the processor, for example, a CPU (Central Processing Unit) can be used. As the recording medium, a “non-temporary tangible medium” such as a ROM (Read Only Memory), a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. Further, a RAM (Random Access Memory) for expanding the program may be further provided. Further, the program may be supplied to the computer via any transmission medium (such as a communication network or a broadcast wave) that can transmit the program. Note that one aspect of the present disclosure can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

[Additional Notes]
One aspect of the present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the technical means disclosed in different embodiments can be appropriately combined. Embodiments to be included are also included in the technical scope of one aspect of the present disclosure. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

(Cross-reference of related applications)
This application claims the benefit of priority to the Japanese patent application filed on April 19, 2018: Japanese Patent Application No. 2018-080882. Included in this document.

1, 2, 3 Display device 10 Control device 11 LD processing unit 12 Display panel drive unit 13 BL drive unit 60 Battery 81 Display panel 82 BL (Backlight)
110, 210, 310 Information acquisition unit 111 Battery connection state detection unit (first information acquisition unit)
112 Battery remaining amount detection unit (first information acquisition unit)
113 Setting condition detection unit (first information acquisition unit)
120 mode selection unit 211 refresh rate detection unit (second information acquisition unit)
212 Elapsed time detection unit (second information acquisition unit)
311 App type determination unit (third information acquisition unit)
312 Screen occupancy rate detection unit (third information acquisition unit)
820 Light source 6000 Charging device Area (1, 1) to Area (3, 3) Control area (area where emission intensity can be changed independently)
LD Mode 1 (first local dimming mode)
LD Mode 2 (second local dimming mode)
LD Mode 3 (third local dimming mode)
LD Mode 4 (another example of the fourth local dimming mode and the first local dimming mode)
LD Mode 5 (Another example of the fifth local dimming mode and the second local dimming mode)
LD Mode 6 (another example of the sixth local dimming mode and the third local dimming mode)

Claims

A display device comprising a backlight divided into a plurality of areas whose emission intensity can be changed independently of each other,
A display panel;
A battery that can be charged and that supplies power to the backlight;
A control device for controlling the backlight,
The display device can operate in (i) a first local dimming mode, or (ii) a second local dimming mode in which power consumption is different from that of the first local dimming mode,
The control device
An information acquisition unit that acquires first information that is at least one of (i) information related to the battery and (ii) information related to power consumption of the display device;
And a mode selection unit that selects the first local dimming mode or the second local dimming mode based on the first information.
The display device can operate in a third local dimming mode, which has different power consumption from the first local dimming mode and the second local dimming mode,
The mode selection unit selects one of the first local dimming mode, the second local dimming mode, and the third local dimming mode based on the first information. The display device described.
The battery can be electrically connected to a charging device capable of charging the battery,
For information on the above battery,
(I) information indicating an electrical connection state between the battery and the charging device, and
The display device according to claim 2, wherein at least one of (ii) information indicating a charging rate of the battery is included.
The information acquisition unit further acquires second information that is information related to a refresh rate of the display panel,
The mode selection unit further selects one of the first local dimming mode, the second local dimming mode, and the third local dimming mode based on the second information. Or the display apparatus of 3.
The information acquisition unit further acquires third information that is information related to application software being executed by the display device,
The mode selection unit further selects one of the first local dimming mode, the second local dimming mode, and the third local dimming mode based on the third information. 5. The display device according to any one of items 1 to 4.
The maximum value of the peak luminance of the display panel is set to 400 cd / m 2 or more in each of the first local dimming mode, the second local dimming mode, and the third local dimming mode. The display device according to any one of 5.
The display device according to any one of claims 1 to 6, wherein the display device is a portable display device.