Display device and head-up display

Abstract

A display device capable of suppressing a temperature rise due to heat generated in a driver circuit is provided. [Solution] The display device 100 includes a plurality of light-emitting units 11 and a current sink 30 including T (T is an integer of 2 or more) driver circuits that realizes local dimming by the plurality of light-emitting units 11 on a light-emitting surface 12 by controlling the sinking of current flowing through the plurality of light-emitting units 11, and each of the T driver circuits is connected to one or more of the plurality of light-emitting units 11, and the light-emitting surface 12 is divided into N (N is an integer of 2 or more) local areas 12i according to the arrangement of the plurality of light-emitting units 11, and when the area of ​​the light-emitting surface 12 is S, the area S of a local area group consisting of one or more local areas 12i that emit light by a specific driver circuit that is any one of the T driver circuits is Tn is S Tn >(S / T+S / N), or S Tn <(S / TS / N) is satisfied.

Description

[Technical Field]

[0001] The present disclosure relates to a display device mounted on, for example, a vehicle. [Background technology]

[0002] In the past, projection-type display devices, such as head-up displays mounted on vehicles, have faced the issue of heat generation from projection light sources. In recent years, however, a solution has been proposed: local dimming, which illuminates the liquid crystal panel area by area (see, for example, Patent Document 1). Such display devices include a liquid crystal panel, a backlight, a temperature detection unit, and a control unit. The backlight is located behind the liquid crystal panel and illuminates only the areas on the liquid crystal panel that have display content, area by area. In other words, local dimming is performed, and heat generation is reduced by not illuminating areas where there is no display content. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-45244 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the display device in Patent Document 1 only takes into consideration the heat generated in the liquid crystal panel, and does not consider the heat generated when the driver circuit draws current. Generally, 10% of the power consumption of the light-emitting section is generated in the driver circuit, so this is not something that can be ignored.

[0005] Therefore, the present disclosure provides a display device and the like that can suppress a temperature rise due to heat generated in a driver circuit. [Means for solving the problem]

[0006] A display device according to one aspect of the present disclosure is a display device that performs local dimming, and includes a plurality of light-emitting units arranged in a matrix, and a current sink unit including T (T is an integer of 2 or more) driver circuits that realizes the local dimming by the plurality of light-emitting units on a light-emitting surface by performing control to sink currents flowing through the plurality of light-emitting units, wherein each of the T driver circuits is connected to one or more of the plurality of light-emitting units, the light-emitting surface is divided into N (N is an integer of 2 or more) local areas according to the arrangement of the plurality of light-emitting units, and when an area of ​​the light-emitting surface is S, an area S of a local area group consisting of one or more local areas that are illuminated by a specific driver circuit that is any one of the T driver circuits is Tn is S Tn >(S / T+S / N), or S Tn <(S / TS / N) is satisfied.

[0007] It should be noted that this comprehensive or specific aspect may be realized by a system or a method, or may be realized by any combination of systems or methods. [Effects of the Invention]

[0008] The display device according to the present disclosure can suppress a temperature rise due to heat generated in the driver circuit.

[0009] Further advantages and benefits of certain aspects of the present disclosure will become apparent from the specification and drawings. Such advantages and / or benefits may be provided by some of the embodiments and features described in the specification and drawings, but not all of them necessarily need to be provided to obtain one or more identical features. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the arrangement and configuration of a head-up display according to an embodiment. [Figure 2]FIG. 2 is a diagram showing an example of the interior of a vehicle equipped with a head-up display according to the embodiment. [Figure 3] FIG. 3 is a diagram showing a specific example of a display object that appears in the display range in the embodiment. [Figure 4] FIG. 4 is a diagram showing an example of a schematic configuration of a display device according to the embodiment. [Figure 5] FIG. 5 is a diagram for explaining heat generated in a current draw section included in a display device for comparison. [Figure 6] FIG. 6 is a diagram illustrating the configuration of a display device according to an embodiment and heat generated in a current draw section included in the display device. [Figure 7] FIG. 7 is a diagram illustrating the configuration of a display device according to the first modification of the embodiment and heat generated in a current draw section included in the display device. [Figure 8] FIG. 8 is a diagram showing an example of timing at which the driver circuits are switched in the first modification of the embodiment. [Figure 9] FIG. 9 is a diagram for explaining that the average power consumption of the second driver circuit and the third driver circuit in the first modification of the embodiment is approximately equal. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of a driver circuit according to the second modification of the embodiment. [Figure 11] FIG. 11 is a diagram showing another configuration example of the driver circuit according to the second modification of the embodiment. [Figure 12] FIG. 12 is a diagram showing yet another example of the configuration of the driver circuit in the second modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Findings that formed the basis of this disclosure) The present inventors have found that the display device of Patent Document 1 described in the "Background Art" section has the following problems.

[0012] The display device of Patent Document 1 performs local dimming as described above. In this local dimming, the backlight independently dims each of the multiple areas included in the liquid crystal panel. By selectively illuminating the area where the display image is displayed, it is possible to reduce the power consumption of the backlight and suppress the amount of heat generated by the backlight.

[0013] Here, the control unit may include multiple driver circuits, the number of which corresponds to the number of areas included in the liquid crystal panel. Furthermore, the multiple areas included in the liquid crystal panel may include one or more areas where a display image is always displayed or frequently displayed (hereinafter also referred to as "constant display areas") and one or more areas where a display image is never displayed or is displayed infrequently (hereinafter also referred to as "emergency display areas"). In such a case, if multiple driver circuits control the same number of areas, i.e., if they control areas of the backlight with the same surface area, uneven heat generation among the driver circuits is likely to occur. For example, if one driver circuit controls only m areas (m is an integer greater than or equal to 1) that are constant display areas, that driver circuit will steadily generate a large amount of heat, resulting in a high time-averaged heat generation. On the other hand, if another driver circuit controls only m areas that are emergency display areas, that driver circuit will be off most of the time, resulting in a low time-averaged heat generation. As described above, the display device of Patent Document 1 has a problem in that when multiple driver circuits each control an area of ​​the backlight that is the same size, there is a tendency for the heat generated by those driver circuits to be uneven.

[0014] In order to solve such problems, a display device according to a first aspect of the present disclosure is a display device that performs local dimming, and includes a plurality of light-emitting units arranged in a matrix, and a current sink unit including T (T is an integer of 2 or more) driver circuits that realizes the local dimming by the plurality of light-emitting units on a light-emitting surface by performing control for sinking currents flowing through the plurality of light-emitting units, wherein each of the T driver circuits is connected to one or more of the plurality of light-emitting units, the light-emitting surface is divided into N (N is an integer of 2 or more) local areas according to the arrangement of the plurality of light-emitting units, and when an area of ​​the light-emitting surface is S, an area S of a local area group consisting of one or more local areas that emit light by a specific driver circuit that is any one of the T driver circuits is Tn is S Tn >(S / T+S / N), or S Tn <(S / TS / N) is satisfied. S / T is the area of ​​the liquid crystal panel divided by the number of driver circuits and is the average area of ​​the region controlled by one driver circuit (hereinafter also referred to as the first average area), and S / N is the average area of ​​the local area that can be individually controlled by local dimming (hereinafter also referred to as the second average area). Furthermore, the local area may be composed of multiple light-emitting units, for example, multiple backlights.

[0015] As a result, the area S of a group of local areas consisting of one or more local areas that are illuminated by a specific driver circuit is Tn is greater than the sum of the first average area (S / T) and the second average area (S / N), the areas of the local area groups controlled by at least two driver circuits can be made different from each other. Tnis smaller than the difference between the first average area (S / T) and the second average area (S / N), the areas of the local area groups controlled by at least two driver circuits can be made different from each other. As a result, even if the liquid crystal panel has a constant display area and an emergency display area, by determining the local area group according to the average heat generation amount of each local area, it is possible to suppress uneven distribution of heat generated in the current sinks, i.e., the T driver circuits. Therefore, it is possible to suppress temperature rise due to heat generated in the driver circuits.

[0016] In a display device according to a second aspect, the light-emitting surface may include a first region and a second region, the first region including one or more of the N local areas, and the second region including one or more of the N local areas, and may emit light for a longer period of time than the first region. Note that the second aspect may be dependent on the first aspect. The first region may be, for example, a region corresponding to an emergency display region in the liquid crystal panel described above, and the second region may be, for example, a region corresponding to a constant display region in the liquid crystal panel described above.

[0017] This makes it possible to suppress uneven distribution of heat generated in the current drawer, i.e., the T driver circuits, when the liquid crystal panel has two areas with different display times, such as a constant display area and an emergency display area.

[0018] In the display device according to a third aspect, the group of local areas that are caused to emit light by the specific driver circuit may include a local area in the second region. Note that the third aspect may be dependent on the second aspect.

[0019] This allows S Tn When <(S / TS / N) is satisfied, even if the display frequency of the local area group corresponding to a specific driver circuit (Tn) is high and the local area group emits light for a relatively long time, the area S TnTherefore, the heat generated in the specific driver circuit can be reduced to approximately the same level as the other driver circuits.

[0020] In addition, the display device according to a fourth aspect may further include a control unit that controls the T driver circuits, and the control unit may switch one of the T driver circuits that draws a current flowing through any one of the plurality of light-emitting units to another driver circuit. Note that the fourth aspect may be subordinate to any one of the first to third aspects.

[0021] This makes it possible to further suppress uneven distribution of heat generated in the two driver circuits that are switched between each other.

[0022] In addition, in the display device according to a fifth aspect, the T driver circuits may include two driver circuits, and the number of light-emitting units connected to one of the two driver circuits among the plurality of light-emitting units may differ from the number of light-emitting units connected to the other of the two driver circuits by 2 or more. Note that the fifth aspect may be dependent on any one of the first to fourth aspects.

[0023] As a result, the number of light-emitting units connected to each of the two driver circuits differs by at least 2. Therefore, even if the multiple light-emitting units include one or more light-emitting units that generate a lot of power and one or more light-emitting units that generate a little power, it is possible to increase the likelihood that the average power consumption of those driver circuits will be approximately equal.

[0024] In a display device according to a sixth aspect, each of at least one of the T driver circuits may have a plurality of terminals, the plurality of terminals including a plurality of connection terminals, each of which is connected to one of the plurality of light-emitting units, and a terminal not connected to the one light-emitting unit may be disposed between two of the plurality of connection terminals. Note that the sixth aspect may be dependent on any one of the first to fifth aspects.

[0025] As a result, all of the multiple connection terminals are distributed and not adjacent to each other, and the channels corresponding to these connection terminals can also be distributed. This allows the heat generated in these channels to be dispersed. The channels are switches, such as transistors, that draw current. This makes it possible to suppress uneven distribution of heat generated in the driver circuit.

[0026] In a display device according to a seventh aspect, each of at least one of the T driver circuits has a plurality of channels that switch current draw on and off, the plurality of channels including a plurality of connection channels, each of which is connected to one of the plurality of light-emitting units, and a channel that is not connected to the one light-emitting unit is disposed between two of the plurality of connection channels. Note that the seventh aspect may be dependent on any one of the first to sixth aspects.

[0027] As a result, all of the connection channels are arranged in a dispersed manner without being adjacent to each other, so that the heat generated in these channels can be dispersed, thereby suppressing uneven distribution of heat generated in the driver circuit.

[0028] Furthermore, a head-up display according to a first aspect of the present disclosure includes a display device according to any one of the first to seventh aspects, a mirror that reflects light emitted from the display device, and a housing that houses the display device and the mirror.

[0029] This makes it possible to achieve the same effects as the display device according to any one of the first to seventh aspects described above.

[0030] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0031] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in the independent claims that represent the highest concepts are described as optional components.

[0032] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Furthermore, in each figure, the same components are assigned the same reference numerals. Furthermore, in the following embodiments, expressions such as "approximately equal" are used. For example, "approximately equal" does not only mean completely equal, but also means substantially equal, that is, including an error of, for example, a few percent. Furthermore, "approximately equal" means equal within the range in which the effects of the present disclosure can be achieved. The same applies to other expressions using "approximately".

[0033] (Embodiment) FIG. 1 is a diagram showing the arrangement and configuration of a head-up display in this embodiment. In this embodiment, the vertical direction is referred to as the Z-axis direction, the fore-and-aft direction of the vehicle V is referred to as the Y-axis direction, and the left-and-right direction of the vehicle V is referred to as the X-axis direction. The positive side of the Z-axis direction is up, upward, upward-facing, or upward side, and the negative side of the Z-axis direction is down, downward, downward-facing, or downward side. The Y-axis direction is parallel to the horizontal direction, the positive side of the Y-axis direction is front, forward, forward-facing, or forward side, and the negative side of the Y-axis direction is rear, rear, backward-facing, or rear side. The X-axis direction is parallel to the horizontal direction, the positive side of the X-axis direction is right, right-facing, or right side, and the negative side of the X-axis direction is left, left-facing, or left side.

[0034] The head-up display 400 in this embodiment is mounted on, for example, a vehicle V and forms a virtual image 1. This virtual image 1 is visually recognized by an observer U who is a driver of the vehicle V, as if it were present, for example, in front of and outside the vehicle V. Such a head-up display 400 includes a housing 300, a display device 100, and a mirror 200.

[0035] The housing 300 is, for example, a resin molded product, and is disposed inside the dashboard of the vehicle V. The housing 300 also houses the display device 100 and the mirror 200.

[0036] The display device 100 emits light representing an image from a display surface. That is, the display device 100 displays an image that is visually recognized by an observer U as a virtual image 1. The display device 100 is, for example, a PGU (Picture Generation Unit) having an LCD (Liquid Crystal Display). The LCD has a liquid crystal panel and a backlight, and performs local dimming.

[0037] The mirror 200 reflects the light emitted from the display device 100 and guides it to the windshield W, thereby forming a virtual image 1 on the side of the windshield W opposite the observer U. That is, when the mirror 200 receives the light emitted from the display device 100, it reflects the light toward the windshield W. For example, the mirror 200 reflects the light toward the upper side of the vehicle V. As a result, when the windshield W receives the light from the mirror 200, it reflects the light toward the pupil of the observer U. This allows the observer U to view, through the windshield W, objects such as a road, pedestrians, or structures in front of and outside the vehicle V, as well as the virtual image 1 superimposed on the objects.

[0038] FIG. 2 is a diagram showing an example of the interior of a vehicle V equipped with a head-up display 400 according to this embodiment.

[0039] The head-up display 400 is hidden within the dashboard 2 and projects light onto the windshield W. By projecting light from the head-up display 400, a display object 3a appears as a virtual image 1 within a display range d on the windshield W. The display object 3a is, for example, an arrow indicating the traveling direction of the vehicle V.

[0040] FIG. 3 is a diagram showing a specific example of an object that appears in the display range d.

[0041] For example, in the display range d, not only the above-mentioned display object 3a but also the display object 3b appears as the virtual image 1. The display object 3b may represent, for example, a water temperature gauge, a speedometer, a gas meter, or a speed limit. The display range d is divided into a plurality of divided areas dn. For example, the plurality of divided areas dn are arranged in a matrix of 3 rows and 4 columns. The three rows are row A1, row A2, and row A3, and the four columns are column B1, column B2, column B3, and column B4. Note that the number of rows and columns is merely an example and is not limited to the above-mentioned numerical values.

[0042] The head-up display 400 adjusts the light intensity for each divided area dn. More specifically, the head-up display 400 switches, for example, each divided area dn between on and off by local dimming by the display device 100. When a divided area dn is turned on, a displayed object is displayed in that divided area dn, and when the divided area dn is turned off, the displayed object is hidden in that divided area dn.

[0043] Here, display objects such as display object 3a are not always displayed, but are displayed in eight divided areas dn in rows A1 and A2 in display range d depending on the state of vehicle V or operations by observer U. On the other hand, display objects such as display object 3b are almost always displayed in four divided areas dn in row A3 in display range d, regardless of the state of vehicle V or operations by observer U. Therefore, the area consisting of four divided areas dn in row A1 and the area consisting of four divided areas dn in row A2 are each called an emergency display area. On the other hand, the area consisting of four divided areas dn in row A3 is called a constant display area.

[0044] FIG. 4 is a diagram showing an example of a schematic configuration of the display device 100. As shown in FIG.

[0045] The display device 100 includes a backlight 10, a voltage generating section 20, and a current sink 30.

[0046] The backlight 10 includes a plurality of light-emitting units 11. Each of the plurality of light-emitting units 11 is, for example, an LED (Light Emitting Diode). A voltage generating unit 20 generates a voltage to be applied to the backlight 10. A current drawing unit 30 performs control to draw current flowing through the plurality of light-emitting units 11 included in the backlight 10. Through this control, the current drawing unit 30 realizes local dimming by the plurality of light-emitting units 11 on the light-emitting surface of the backlight 10.

[0047] Here, of the heat generated in the display device 100, for example, 90% is generated in the backlight 10, and 10% is generated in the current drawer 30. The display device 100 in this embodiment suppresses uneven distribution of heat generated in the current drawer 30.

[0048] FIG. 5 is a diagram for explaining heat generated in current draw section 30 included in the display device for comparison.

[0049] The comparative display device 100x includes a current sink 30 and a backlight 10. The backlight 10 includes twelve light-emitting units 11. As shown in FIG. 5, these twelve light-emitting units 11 are arranged in a matrix of three rows and four columns. The three rows are rows A1, A2, and A3, and the four columns are columns B1, B2, B3, and B4. As shown in FIG. 5, the light-emitting surface 12 of the backlight 10 is divided into twelve local areas 12i according to the arrangement of the twelve light-emitting units 11.

[0050] The current sink 30 includes a first driver circuit 30a, a second driver circuit 30b, and a third driver circuit 30c. Each of the first driver circuit 30a, the second driver circuit 30b, and the third driver circuit 30c is configured as, for example, an IC (Integrated Circuit), and is collectively referred to simply as a driver circuit.

[0051] For example, the first driver circuit 30a performs control to individually draw current flowing through each of the four light-emitting units 11 in row A1 of the backlight 10. Through this control, the first driver circuit 30a causes each of the four light-emitting units 11 to emit light individually. In other words, each of the four local areas 12i corresponding to each of the light-emitting units 11 emits light individually. Due to the emission of these local areas 12i, display objects are individually displayed in each of the four divided areas dn in row A1 within the display range d shown in FIG. 3.

[0052] The second driver circuit 30b performs control to individually draw current flowing through each of the four light-emitting units 11 in row A2 of the backlight 10, for example. Through this control, the second driver circuit 30b causes each of the four light-emitting units 11 to emit light individually. In other words, each of the four local areas 12i corresponding to each of the light-emitting units 11 emits light individually. Due to the emission of these local areas 12i, display objects are individually displayed in each of the four divided areas dn in row A2 within the display range d shown in FIG. 3.

[0053] The third driver circuit 30c performs control to individually draw current flowing through each of the four light-emitting units 11 in row A3 of the backlight 10, for example. Through this control, the third driver circuit 30c causes each of the four light-emitting units 11 to emit light individually. In other words, each of the four local areas 12i corresponding to each of the light-emitting units 11 emits light individually. Due to the emission of light from these local areas 12i, display objects are individually displayed in each of the four divided areas dn in row A3 within the display range d shown in FIG. 3.

[0054] Here, the area consisting of four divided areas dn in row A1 of display range d and the area consisting of four divided areas dn in row A2 of display range d are each an emergency display area. The area consisting of four divided areas dn in row A3 of display range d is a constant display area. In the emergency display area, for example, display object 3a is displayed for 30% of a predetermined period. In the constant display area, for example, display object 3b is displayed for 90% of a predetermined period. The percentages such as 30% and 90% are hereinafter also referred to as display rates.

[0055] As a result, if the power consumption when one local area 12i is continuously lit is set to 1, the average power consumption over time of each of the first driver circuit 30a and the second driver circuit 30b is 0.3×4=1.2. Furthermore, the average power consumption over time of the third driver circuit 30c is 0.9×4=3.6. Note that, because the display ratio of the emergency display area is 30%, the average power generated in one local area 12i corresponding to the emergency display area is expressed as 0.3. Similarly, because the display ratio of the constant display area is 90%, the average power generated in one local area 12i corresponding to the constant display area is expressed as 0.9.

[0056] In this way, the average power consumption differs among the driver circuits, which causes a bias in the amount of heat generated among the driver circuits, that is, the third driver circuit 30c generates more heat.

[0057] FIG. 6 is a diagram illustrating the configuration of display device 100 according to the present embodiment and heat generated by current drawing section 30 included in display device 100. In FIG.

[0058] The backlight 10 includes 12 light-emitting units 11, as in the example of FIG. 5. These 12 light-emitting units 11 are arranged in a matrix of 3 rows and 4 columns, as shown in FIG. 6. The light-emitting surface 12 of the backlight 10 is divided into 12 local areas 12i according to the arrangement of the 12 light-emitting units 11, as shown in FIG. 6. That is, the light-emitting surface 12 of the backlight 10 is divided into N local areas 12i (N is an integer of 2 or more) according to the arrangement of the plurality of light-emitting units 11. In the example of FIG. 6, N=12. Each local area 12i is, for example, an area illuminated by one light-emitting unit 11, and has an equal area to one another.

[0059] Similar to the example of FIG. 5, the current sink 30 includes a first driver circuit 30a, a second driver circuit 30b, and a third driver circuit 30c.

[0060] The first driver circuit 30a in this embodiment is connected to four light-emitting units 11 in row A1 of the backlight 10 and one light-emitting unit 11 in row A3 and column B2 of the backlight 10, and performs control to individually draw current flowing through these light-emitting units 11. Through this control, the first driver circuit 30a causes each of these five light-emitting units 11 to emit light individually. In other words, each of the five local areas 12i corresponding to each of these light-emitting units 11 emits light individually. Through the emission of these local areas 12i, displayed objects are individually displayed in four divided areas dn in row A1 within the display range d shown in FIG. 3 and one divided area dn in row A3 and column B2 within the display range d.

[0061] The second driver circuit 30b in this embodiment is connected to four light-emitting units 11 in row A2 of the backlight 10 and one light-emitting unit 11 in row A3 and column B1 of the backlight 10, and performs control to individually draw current flowing through these light-emitting units 11. Through this control, the second driver circuit 30b individually causes each of these five light-emitting units 11 to emit light. In other words, each of the five local areas 12i corresponding to each of these light-emitting units 11 individually emits light. Through the emission of these local areas 12i, displayed objects are individually displayed in four divided areas dn in row A2 within the display range d shown in FIG. 3 and one divided area dn in row A3 and column B1 within the display range d.

[0062] The third driver circuit 30c in this embodiment is connected to one light-emitting unit 11 in row A3 and column B3 of the backlight 10 and one light-emitting unit 11 in row A3 and column B4 of the backlight 10, and performs control to individually draw current flowing through those light-emitting units 11. Through this control, the third driver circuit 30c causes each of those two light-emitting units 11 to emit light individually. In other words, each of the two local areas 12i corresponding to those light-emitting units 11 emits light individually. Due to the emission of these local areas 12i, objects are individually displayed in one divided area dn in row A3 and row B3 within the display range d shown in FIG. 3 and one divided area dn in row A3 and column B4 within the display range d.

[0063] Here, as described above, the display ratio of the emergency display area of ​​display range d is, for example, 30%, and the display ratio of the constant display area is 90%. As a result, the average power consumption of each of the first driver circuit 30a and the second driver circuit 30b is 0.3×4+0.9=2.1. Furthermore, the average power consumption of the third driver circuit 30c is 0.9×2=1.8.

[0064] In this way, in the display device 100 according to the present embodiment, the variation in the average power consumption of each driver circuit can be reduced more than in the above-described display device 100x, and as a result, uneven distribution of heat generated in those driver circuits can be reduced.

[0065] 6, the current sink 30 includes three driver circuits, but the number of driver circuits included in the current sink 30 is not limited to three and may be any number equal to or greater than 2. Also, in the example of Fig. 6, the number of light-emitting units 11 connected to one driver circuit is five or two, but the number is not limited to these numbers and may be any number equal to or greater than 1.

[0066] That is, the current sink 30 in this embodiment includes T driver circuits (T is an integer of 2 or more). Each of the T driver circuits is connected to one or more of the plurality of light-emitting units 11. In this embodiment, when the total area of ​​the light-emitting surface 12 of the backlight 10 is S, the area S of a local area group consisting of one or more local areas 12i that are emitted by a specific driver circuit that is any one of the T driver circuits is Tn is S Tn In the example of FIG. 6, the specific driver circuit is the third driver circuit 30c, but if any of the T driver circuits satisfies S Tn <(S / TS / N) condition must be met.

[0067] Specifically, in the example of FIG. 6, the area S of a local area group consisting of one or more local areas 12i that are emitted by the third driver circuit 30c is Tn is 2. The area of ​​one local area 12i is 1. The area S of the light emitting surface 12 is 12, the number T of driver circuits is 3, and the number N of local areas 12i is 12. As a result, S Tn (=2) is smaller than (S / TS / N)=(12 / 3-12 / 12)=3. Therefore, S Tn <(S / TS / N) is satisfied.

[0068] Here, S / T is the average area (also referred to as the first average area) of the local area group controlled by one driver circuit, and S / N is the average area (also referred to as the second average area) of the local area 12i. Therefore, in this embodiment, the area S of the local area group consisting of one or more local areas 12i that emit light by a specific driver circuit is Tn is smaller than the difference between the first average area (S / T) and the second average area (S / N). Tn However, by making it different from the first average area (S / T), it is possible to suppress uneven distribution of heat generated in each driver circuit.

[0069] Area S Tn However, by making the area different from the first average area (S / T), it is possible to suppress the uneven distribution of heat generated in each driver circuit. Tn is S Tn > (S / T+S / N). In other words, the area S Tn is greater than the sum of the first average area (S / T) and the second average area (S / N). For example, the specific driver circuit is the first driver circuit 30a, and the first driver circuit 30a is connected to four light-emitting units 11 in row A1 of the backlight 10, one light-emitting unit 11 in row A3 and column B2, and one light-emitting unit 11 in row A3 and column B3. In this case, the area S Tn is the sum of the areas of the four local areas 12i in row A1, one local area 12i in row A3 and column B2, and one local area 12i in row A3 and column B3, which is 6. As a result, S Tn (=6) is greater than (S / T+S / N)=(12 / 3+12 / 12)=5. Therefore, S Tn > (S / T+S / N) is satisfied. In this case, too, the area S Tn However, by making it different from the first average area (S / T), it is possible to suppress uneven distribution of heat generated in each driver circuit.

[0070] In this way, in this embodiment, the area STn is S Tn >(S / T+S / N), or S Tn <(S / TS / N) is satisfied. This makes it possible to suppress uneven distribution of heat generated in each driver circuit. In other words, the area S of a local area group consisting of one or more local areas 12i that emit light by a specific driver circuit is Tn is greater than the sum of the first average area (S / T) and the second average area (S / N), the areas of the local area groups controlled by at least two driver circuits can be made different from each other. Tn is smaller than the difference between the first average area (S / T) and the second average area (S / N), the areas of the local area groups controlled by at least two driver circuits can be made different. As a result, even if the liquid crystal panel has a constant display area and an emergency display area, by determining the local area group according to the average heat generation amount of each local area 12i, it is possible to suppress uneven distribution of heat generated in the current drawer 30, i.e., the T driver circuits. Therefore, it is possible to suppress temperature rise due to heat generated in the driver circuits.

[0071] In the present embodiment, the light-emitting surface 12 includes a first region and a second region. The first region includes one or more of the N local areas 12i. The second region includes one or more of the N local areas 12i and emits light for a longer period of time than the first region. In the example of FIG. 6 , the first region includes four local areas 12i in row A1 or row A2 of the backlight 10 and corresponds to the emergency display region. The second region includes four local areas 12i in row A3 of the backlight 10 and corresponds to the constant display region. This configuration can suppress uneven distribution of heat in the current sink 30, i.e., the T driver circuits, when the liquid crystal panel includes two regions with different display times, such as the constant display region and the emergency display region.

[0072] Furthermore, in this embodiment, the group of local areas that are caused to emit light by a specific driver circuit includes a local area 12i in the second region. Note that the group of local areas may include only one or more local areas 12i in the second region. In the example of FIG. 6, the group of local areas that are caused to emit light by the third driver circuit 30c, which is a specific driver circuit, includes only two local areas 12i in the second region. The two local areas 12i in the second region are the local area 12i in row A3 and column B3, and the local area 12i in row A3 and column B4. This allows S Tn When <(S / TS / N) is satisfied, the display frequency of the local area group corresponding to a specific driver circuit (Tn) is high, and even if the local area group emits light for a relatively long time, the area S Tn Therefore, the heat generated in the specific driver circuit can be reduced to approximately the same level as the other driver circuits.

[0073] Furthermore, in this embodiment, the T driver circuits include two driver circuits, and the number of light-emitting units 11 connected to one of the two driver circuits differs by two or more from the number of light-emitting units 11 connected to the other of the two driver circuits. In the example of FIG. 6 , the two driver circuits are, for example, the second driver circuit 30b and the third driver circuit 30c. The number of light-emitting units 11 connected to the second driver circuit 30b is five, and the number of light-emitting units 11 connected to the third driver circuit 30c is two. Therefore, the number of light-emitting units 11 connected to the second driver circuit 30b differs by two or more from the number of light-emitting units 11 connected to the third driver circuit 30c. This results in a difference of two or more from the number of light-emitting units 11 connected to each of the two driver circuits. Therefore, even if the multiple light-emitting units 11 include one or more light-emitting units 11 with high power generation and one or more light-emitting units 11 with low power generation, it is possible to increase the likelihood that the average power consumption of the two driver circuits will be approximately equal.

[0074] In addition, in this embodiment, it can be said that each driver circuit and each light-emitting unit 11 are connected so that the average power consumption of each driver circuit is approximately equal, that is, so that the average power consumption is uniform, depending on the light-emitting time of each light-emitting unit 11. Note that the above-mentioned average means the average over time.

[0075] (Variation 1) Furthermore, in the display device of this modified example, two driver circuits alternately draw current flowing through one light-emitting unit 11.

[0076] FIG. 7 is a diagram for explaining the configuration of a display device in this modified example and the heat generated in current drawing section 30 included in the display device.

[0077] The display device 100a in this modification includes a control unit 40 that controls three driver circuits, namely, a first driver circuit 30a, a second driver circuit 30b, and a third driver circuit 30c. In other words, the display device 100a includes a control unit 40 that controls T driver circuits. The control unit 40 switches one of the T driver circuits, which draws current flowing through one of the plurality of light-emitting units 11, to another driver circuit.

[0078] For example, the control unit 40 alternately switches the driver circuit that draws current through the light-emitting unit 11 located in row A3 and column B2 between the first driver circuit 30a and the third driver circuit 30c. For example, the control unit 40 causes the first driver circuit 30a and the third driver circuit 30c to draw current through the light-emitting unit 11 at a time ratio of ta1:ta3. That is, the control unit 40 causes the first driver circuit 30a to draw current through the light-emitting unit 11 for time ta1, and then causes the third driver circuit 30c to draw current through the light-emitting unit 11 for time ta3. The control unit 40 alternates between drawing current through the first driver circuit 30a and the third driver circuit 30c.

[0079] As a result, the current flowing through the light-emitting unit 11 in row A3 and column B2 is drawn into the first driver circuit 30a via the first path L1 during time ta1, and into the third driver circuit 30c via the second path L2 during time ta3.

[0080] Similarly, the control unit 40 alternately switches the driver circuit that draws the current flowing through the light-emitting unit 11 located in row A3 and column B1 between the second driver circuit 30b and the third driver circuit 30c. For example, the control unit 40 causes the second driver circuit 30b and the third driver circuit 30c to draw the current flowing through the light-emitting unit 11 at a time ratio of tb2:tb3. That is, the control unit 40 causes the second driver circuit 30b to draw the current flowing through the light-emitting unit 11 for time tb2, and then causes the third driver circuit 30c to draw the current flowing through the light-emitting unit 11 for time tb3. The control unit 40 alternates between drawing the current through the second driver circuit 30b and the third driver circuit 30c.

[0081] As a result, the current flowing through the light-emitting unit 11 in row A3 and column B1 is drawn into the second driver circuit 30b via the first path L1 during time tb2, and into the third driver circuit 30c via the second path L2 during time tb3.

[0082] In this modification, as in the above embodiment, the first driver circuit 30a draws current flowing through the four light-emitting units 11 in row A1 of the backlight 10. The second driver circuit 30b draws current flowing through the four light-emitting units 11 in row A2 of the backlight 10. The third driver circuit 30c draws current flowing through the light-emitting units 11 in row A3 and column B3 and the light-emitting units 11 in row A3 and column B4.

[0083] This allows the average power consumption of each of the first driver circuit 30a, the second driver circuit 30b, and the third driver circuit 30c to be approximately equal, for example, to 2.0. In other words, in the display device 100a of this modification, the average power consumption of each driver circuit can be made even more approximately equal than in the display device 100 of the above embodiment, and uneven distribution of heat can be further suppressed.

[0084] Fig. 8 is a diagram showing an example of timing at which the driver circuits are switched, that is, Fig. 8 shows timing at which a current flows through the first path L1 and timing at which a current flows through the second path L2.

[0085] The control unit 40 switches the driver circuit that draws the current flowing through the light-emitting unit 11 between the light-emitting unit 11 in row A3 and column B2 and the light-emitting unit 11 in row A3 and column B1. Specifically, the control unit 40 switches the driver circuit that draws the current flowing through the light-emitting unit 11 in row A3 and column B2 to the first driver circuit 30a. Furthermore, the control unit 40 switches the driver circuit that draws the current flowing through the light-emitting unit 11 in row A3 and column B1 to the second driver circuit 30b.

[0086] As a result, a current flows through the first path L1. For example, the control unit 40 switches the driver circuit so that a current flows through the first path L1 (i.e., the current is on) for 89% of the time that a current flows through the light-emitting unit 11 in row A3 and column B2 and the light-emitting unit 11 in row A3 and column B1.

[0087] Thereafter, the control unit 40 switches the driver circuit that draws current flowing through the light-emitting units 11 in row A3 and column B2 to the third driver circuit 30c. Furthermore, the control unit 40 switches the driver circuit that draws current flowing through the light-emitting units 11 in row A3 and column B1 to the third driver circuit 30c. As a result, current flows through the second path L2. For example, the control unit 40 switches the driver circuit so that current flows through the second path L2 (i.e., so that current is on) for 11% of the time that current flows through the light-emitting units 11 in row A3 and column B2 and the light-emitting units 11 in row A3 and column B1.

[0088] As a result, the first driver circuit 30a and the third driver circuit 30c draw in, in a time-division manner, the current flowing through the light-emitting unit 11 on row A1 and column B2 at a time ratio of ta1:ta3 = 89:11. Similarly, the second driver circuit 30b and the third driver circuit 30c draw in, in a time-division manner, the current flowing through the light-emitting unit 11 on row A1 and column B1 at a time ratio of tb2:tb3 = 89:11.

[0089] FIG. 9 is a diagram for explaining that the average power consumption of the second driver circuit 30b and the average power consumption of the third driver circuit 30c are approximately equal.

[0090] The second driver circuit 30b draws current through the four light-emitting units 11 in row A2 of the backlight 10. The average power generated by each of the four light-emitting units 11 is 0.3. Therefore, the average power consumption of that current draw is 0.3 × 4 = 1.2. Furthermore, the second driver circuit 30b draws 89% of the current through the light-emitting units 11 in row A3 and column B1. The average power generated by those light-emitting units 11 is 0.9. Therefore, the average power consumption of that current draw is 0.9 × 0.89 ≒ 0.8. As a result, the average power consumption of the second driver circuit 30b is 1.2 + 0.8 = 2.0.

[0091] The third driver circuit 30c draws current through the light-emitting units 11 in row A3 and column B3 of the backlight 10 and the light-emitting units 11 in row A3 and column B4. The average power generated by these light-emitting units 11 is 0.9. Therefore, the average power consumption of these current draws is 0.9 × 2 = 1.8. Furthermore, the third driver circuit 30c draws 11% of the current flowing through the light-emitting units 11 in row A3 and column B1 and 11% of the current flowing through the light-emitting units 11 in row A3 and column B2. The average power generated by these light-emitting units 11 is also 0.9. Therefore, the average power consumption of these current draws is 0.9 × 0.11 × 2 ≈ 0.2. As a result, the average power consumption of the third driver circuit 30c is 1.8 + 0.2 = 2.0.

[0092] In this way, the average power consumption of the second driver circuit 30b and the third driver circuit 30c can be made approximately equal to 2.0. Similarly, the average power consumption of the first driver circuit 30a can also be made 2.0. As a result, the average power consumption of the first driver circuit 30a, the second driver circuit 30b, and the third driver circuit 30c can be made substantially equal. In other words, the uneven distribution of heat generated between the two driver circuits that are switched between each other can be further suppressed. As a result, in this modification, the uneven distribution of heat generated can be further suppressed than in the display device 100 of the above embodiment.

[0093] In this modification, as in the above embodiment, the area S of a local area group consisting of one or more local areas 12i that are emitted by a specific driver circuit is Tn is 2 and S Tn <(S / TS / N). That is, the specific driver circuit in this modification is the third driver circuit 30c, and the number of local areas 12i that are emitted only by the third driver circuit 30c is two. The two local areas 12i are the local area 12i located on row A3 and column B3, and the local area 12i located on row A3 and column B4. Therefore, the area S Tn can be said to be 2.

[0094] (Variation 2) In the display device of this modified example, the channels and terminals included in the driver circuit are distributed.

[0095] FIG. 10 is a diagram illustrating an example of the configuration of a driver circuit.

[0096] The driver circuit 31 included in the current sink 30 has a plurality of channels (specifically, channels CH1 to CH12) as shown in Fig. 10. The driver circuit 31 may be any one of the first driver circuit 30a, the second driver circuit 30b, and the third driver circuit 30c.

[0097] Each of the channels CH1 to CH12 is a switch, such as a transistor, that switches current draw on and off. One light-emitting unit 11 is connected to multiple channels among the channels CH1 to CH12. Specifically, the light-emitting unit 11 is connected to channels CH1, CH5, CH7, CH8, and CH11.

[0098] Here, when channels CH1, CH5, CH7, CH8, and CH11 are arranged adjacent to other channels among them, there is a tendency for uneven heat to be generated in the driver circuit 31. In other words, there is a possibility that heat is more likely to be generated in the portions of the driver circuit 31 where channels CH1, CH5, CH7, CH8, and CH11 are arranged, and less likely to be generated in other portions.

[0099] Therefore, in this modification, the multiple channels connected to the same light-emitting unit 11 are distributed in the driver circuit 31. That is, between any two of the multiple channels (i.e., multiple connection channels) connected to the same light-emitting unit 11, another channel is disposed. The other channel may be connected to a light-emitting unit 11 different from the above-mentioned same light-emitting unit 11, or may not be connected to any light-emitting unit 11.

[0100] Any of the first driver circuit 30a, the second driver circuit 30b, and the third driver circuit 30c may be configured as the driver circuit 31. Furthermore, at least one of the first driver circuit 30a, the second driver circuit 30b, and the third driver circuit 30c may be configured as the driver circuit 31.

[0101] As described above, in this modification, at least one of the T driver circuits has a plurality of channels that switch current draw on and off. In the example of FIG. 10, the plurality of channels are channels CH1 to CH12. The plurality of channels includes a plurality of connection channels, and each of the plurality of connection channels is connected to one of the plurality of light-emitting units 11. In the example of FIG. 10, the plurality of connection channels are channels CH1, CH5, CH7, CH8, and CH11. Between two of the plurality of connection channels, a channel that is not connected to the one light-emitting unit 11 is disposed. In the example of FIG. 10, between the two connection channels, channel CH1 and channel CH5, channels CH2 to CH4 that are not connected to the one light-emitting unit 11 are disposed.

[0102] As a result, all of the connection channels are arranged in a dispersed manner without being adjacent to each other, so that the heat generated in these channels can be dispersed, thereby suppressing uneven distribution of heat generated in the driver circuit 31.

[0103] In the example of FIG. 10, the connection channels are distributed, but the terminals of the connection channels may also be distributed.

[0104] FIG. 11 is a diagram showing another example of the configuration of the driver circuit 31. In FIG.

[0105] 11, the driver circuit 31 included in the current sink 30 has a plurality of channels (specifically, channels CH1 to CH4). The channels CH1 to CH4 have terminals IN1 to IN4 for connection to the light emitting unit 11, respectively.

[0106] In this modification, a plurality of terminals connected to the same light-emitting unit 11 (that is, a plurality of connection terminals) may be distributed in the driver circuit 31.

[0107] As described above, in this modification, at least one of the T driver circuits has a plurality of terminals. In the example of FIG. 11, the plurality of terminals are terminals IN1 to IN4. The plurality of terminals includes a plurality of connection terminals, each of which is connected to one of the plurality of light-emitting units 11. In the example of FIG. 11, the plurality of connection terminals are terminals IN1 and IN4. A terminal that is not connected to the one light-emitting unit 11 is disposed between two of the plurality of connection terminals. In the example of FIG. 11, terminals IN2 and IN3 that are not connected to the one light-emitting unit 11 are disposed between the two connection terminals, terminals IN1 and IN4.

[0108] As a result, all of the connection terminals are distributed and not adjacent to each other, and the connection channels corresponding to these connection terminals can also be distributed. This allows the heat generated in these connection channels to be dispersed, thereby suppressing uneven distribution of heat generated in the driver circuit 31.

[0109] It should be noted that there are cases where the channels and their terminals are not located near each other.

[0110] FIG. 12 is a diagram showing yet another example of the configuration of the driver circuit 31. In FIG.

[0111] 12, the channel CH2 and the terminal IN2 of the channel CH2 are not located near each other. Similarly, the channel CH3 and the terminal IN3 of the channel CH3 are not located near each other, and the channel CH4 and the terminal IN4 of the channel CH4 are not located near each other.

[0112] 12, even if the terminals IN1 and IN2 connected to the same light-emitting unit 11 are distributed, the channels CH1 and CH2 corresponding to the terminals IN1 and IN2 may not be distributed. Therefore, when the plurality of channels and the terminals of the channels are not located near each other, the light-emitting unit 11 and the plurality of connection channels are connected so that the plurality of connection channels are distributed.

[0113] Display devices according to one or more aspects of the present disclosure have been described above based on embodiments and modifications, but the present disclosure is not limited to the embodiments and modifications. Various modifications conceivable by those skilled in the art to the above embodiments and modifications may also be included in the present disclosure, as long as they do not deviate from the spirit of the present disclosure. Furthermore, configurations constructed by combining the components of the embodiments and modifications may also be included in the present disclosure.

[0114] For example, the display device in the above-described embodiment and modified examples is provided in the head-up display 400, but may be provided in another display such as a decorative display. Also, the display device in the above-described embodiment and modified examples does not have to be mounted on a moving body such as the vehicle V.

[0115] Furthermore, in the above-described embodiment and modified examples, one light-emitting unit 11 is arranged in one local area 12i, but two or more light-emitting units 11 may be arranged in one local area 12i. Furthermore, the areas of the respective local areas 12i on the light-emitting surface 12 may be different.

[0116] In addition, in the above-described first modification, the control unit 40 may be configured with dedicated hardware or may be realized by executing a software program. The control unit 40 may also be realized by a program execution unit such as a CPU (Central Processing Unit) or a processor reading and executing a software program recorded on a recording medium such as a hard disk or semiconductor memory. [Industrial Applicability]

[0117] The present disclosure can be used in, for example, a display device mounted on a vehicle. [Explanation of symbols]

[0118] 1 Virtual Image 2. Dashboard 3a, 3b Displayed items 10 Backlight 11 Light-emitting part 12 Light-emitting surface 12i Local Area 20 Voltage generation unit 30 Current draw section 30a First driver circuit 30b Second driver circuit 30c Third driver circuit 31 Driver circuit 40 Control Unit 100, 100a display device 200 mirror 300 cabinets 400 Head-Up Display A1, A2, A3 rows B1, B2, B3, B4 columns CH1~CH12 channels IN1, IN2, IN3, IN4 terminals d Display range dn division area L1 1st pathway L2 Secondary pathway U Observer V vehicle W Windshield

Claims

1. A display device that performs local dimming, A plurality of light emitting units arranged in a matrix; a current sink unit including T (T is an integer of 2 or more) driver circuits that performs control to sink currents flowing through the plurality of light-emitting units, thereby realizing the local dimming by the plurality of light-emitting units on the light-emitting surface; each of the T driver circuits is connected to one or more light-emitting units among the plurality of light-emitting units; the light-emitting surface is divided into N local areas (N is an integer of 2 or more) according to the arrangement of the plurality of light-emitting units, When the area of ​​the light-emitting surface is S, the area S of a local area group consisting of one or more local areas that are emitted by a specific driver circuit that is one of the T driver circuits is Ｔｎ teeth, S Ｔｎ > (S / T + S / N), or S Ｔｎ <(S / T-S / N) fulfill, Display device.

2. the light emitting surface includes a first region and a second region; the first region includes one or more local areas among the N local areas; the second region includes one or more of the N local areas, and emits light for a longer period of time than the first region; The display device according to claim 1 .

3. The local area group that emits light by the specific driver circuit includes: a local area of ​​the second region; The display device according to claim 2 .

4. The display device includes: Further, a control unit for controlling the T driver circuits is provided, the control unit switches a driver circuit that draws a current flowing in any one of the plurality of light-emitting units, among the T driver circuits, to another driver circuit; The display device according to claim 1 .

5. the T driver circuits include two driver circuits; Among the plurality of light-emitting units, the number of light-emitting units connected to one of the two driver circuits differs by two or more from the number of light-emitting units connected to the other of the two driver circuits. The display device according to claim 1 .

6. each of the at least one driver circuit among the T driver circuits has a plurality of terminals; the plurality of terminals includes a plurality of connection terminals, each of the plurality of connection terminals is connected to one of the plurality of light-emitting units; a terminal that is not connected to one of the light-emitting units is disposed between two of the plurality of connection terminals; The display device according to claim 1 .

7. each of the at least one driver circuit among the T driver circuits has a plurality of channels that are switched on and off to draw current; the plurality of channels includes a plurality of connection channels; each of the plurality of connection channels is connected to one of the plurality of light-emitting units; a channel that is not connected to one of the light-emitting units is disposed between two of the plurality of connection channels; The display device according to claim 1 .

8. A display device according to any one of claims 1 to 7; a mirror that reflects light emitted from the display device; a housing that houses the display device and the mirror; A head-up display with.

Images