Display apparatus

Abstract

To provide a display apparatus capable of reducing user's discomfort, eye fatigue, or the like due to an unexpected sudden change in screen luminance.SOLUTION: A display apparatus 100 includes a display section 130, an illuminance sensor 140, a moving object detection section 150, and a screen control section 111. The display section 130 has a display screen 131. The illuminance sensor 140 detects ambient brightness. The moving object detection section 150 detects a motion of an ambient object. The screen control section 111 controls the display screen 131 so that the screen luminance L of the display screen 131 changes in response to a change in brightness detected by the illuminance sensor 140. The screen control section 111 controls the display screen 131 so that first followability, which is the followability of the screen luminance L to the change in brightness when the moving object detection section 150 detects the motion of the object, is smaller than second followability, which is the followability of the screen luminance L to the change in brightness when the motion of the object.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] Patent Document 1 describes a system that includes an illuminance measuring unit such as a CdS cell that measures the brightness near the liquid crystal display panel, and a dimming unit that adjusts the lighting status of the LEDs that backlight the liquid crystal display panel based on the measurement value of the illuminance measuring unit. With this configuration, the brightness of the display unit of the liquid crystal display panel is adjusted to match the ambient illuminance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 6-60830 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, when a user approaches a large display device such as an IWB (Interactive Whiteboard) to operate it, a shadow may be cast depending on the positional relationship with the lighting in the area. If such a shadow causes a sudden change in the ambient brightness measured by the illuminance sensor built into the display device, the display device may mistakenly believe that the surroundings have become dark, causing a sudden change in the brightness of the display screen. Such a sudden change in screen brightness may cause discomfort and eye fatigue to the user.

[0005] An object of the present disclosure is to provide a display device that can reduce discomfort and eye fatigue experienced by a user due to an unexpected sudden change in screen brightness. [Means for solving the problem]

[0006] The display device of the present disclosure includes a display unit, an illuminance sensor, a moving object detection unit, and a screen control unit. The display unit has a display screen. The illuminance sensor detects ambient brightness. The moving object detection unit detects movement of an object in the surrounding area. The screen control unit controls the display screen so that the screen brightness of the display screen changes in accordance with the change in brightness detected by the illuminance sensor. The screen control unit controls the display screen so that a first tracking ability, which is the ability of the screen brightness to follow the change in brightness when the movement of the object is detected by the moving object detection unit, is smaller than a second tracking ability, which is the ability of the screen brightness to follow the change in brightness when the movement of the object is not detected. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a display device that can reduce the discomfort and eye fatigue of a user caused by an unexpected sudden change in screen brightness. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a schematic configuration of a display device 100 according to an embodiment of the present disclosure. [Figure 2] 10 is a graph illustrating an example of screen luminance L controlled in accordance with the ambient brightness. [Figure 3] 10 is a time chart illustrating the responsiveness of the screen luminance L when the ambient brightness changes. [Figure 4] 1 is an explanatory diagram illustrating a case where a user U approaches the display device 100. FIG. [Figure 5] 10 is an explanatory diagram illustrating a case where a user U moves away from the display device 100. FIG. [Figure 6] 6 is a time chart illustrating an example of screen luminance L controlled in accordance with changes in detected illuminance E in the cases of FIGS. 4 and 5. [Figure 7A] 10 is an explanatory diagram illustrating a case where a human body H approaches the display device 100. FIG. [Figure 7B] 7B is an explanatory diagram illustrating a case where the human body H moves away again after FIG. 7A. FIG. [Figure 8] 7C is a time chart illustrating the screen luminance L controlled in accordance with changes in the detected illuminance E in the cases of FIGS. 7A and 7B. [Figure 9] 10 is a flowchart showing an outline of a method for controlling screen luminance L by display device 100. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0010] 1. Configuration of the display device 100 First, with reference to FIGS. 1 to 3, a configuration of a display device 100 that controls the brightness of a display screen 131 in accordance with the ambient brightness and the movement of an object will be described. FIG. 1 is a block diagram showing a schematic configuration of a display device 100 according to an embodiment of the present disclosure. FIG. 2 is a graph illustrating an example of screen brightness L controlled in accordance with the ambient brightness. FIG. 3 is a time chart illustrating the responsiveness of screen brightness L when the ambient brightness changes. The brightness of the display screen 131 will be referred to as "screen brightness L" hereinafter.

[0011] 1, the display device 100 includes a control device 101, a display unit 130, an illuminance sensor 140, and a moving object detection unit 150. The control device 101 includes a CPU (Central Processing Unit) 110 and a storage unit 120. The CPU 110 includes a screen control unit 111.

[0012] The CPU 110 controls each unit of the display device 100. The CPU 110 may be, for example, a processor or an MPU (Micro Processing Unit), but is not limited to these. For example, if an OS (Operating System, sometimes called "basic software") that runs on the CPU 110 and programs for each function corresponding to the screen control unit 111 are stored in the storage unit 120, the screen control unit 111 is realized by the CPU 110 executing the OS and programs. Examples of OS include, but are not limited to, Microsoft Windows (registered trademark), Android (registered trademark), and Linux (registered trademark). The screen control unit 111 may be configured by, for example, an electronic circuit, a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), or the like, but is not limited to these.

[0013] The storage unit 120 stores information, data, etc. necessary for controlling each unit of the display device 100. The storage unit 120 may also store or store an OS, programs, etc. executed by the CPU 110. The storage unit 120 includes memory, specifically, volatile memory and nonvolatile memory. Volatile memory includes, for example, dynamic random access memory (DRAM) and static random access memory (SRAM), but is not limited to these. Nonvolatile memory includes, for example, read-only memory (ROM), flash memory, solid state drive (SSD), and hard disk, but is not limited to these.

[0014] The display unit 130 has a display screen 131. The display unit 130 includes those with and without a memory property. Examples of display units without a memory property include, but are not limited to, liquid crystal and organic electroluminescence (EL). Examples of display units with a memory property include, but are not limited to, electronic paper. Display units 130 are broadly classified into self-luminous types such as organic EL and non-self-luminous types such as liquid crystal. In the self-luminous display unit 130, each pixel of the display screen 131 itself emits light. In the non-self-luminous display unit 130, an illumination light source such as a backlight, a sidelight, or a frontlight is provided.

[0015] Illuminance sensor 140 detects the brightness of the surroundings. The brightness (illuminance) detected by illuminance sensor 140 may be referred to as "detected illuminance E" below.

[0016] The moving object detection unit 150 detects the movement of surrounding objects. Examples of objects include, but are not limited to, human bodies. The minimum function of the moving object detection unit 150 is to be able to detect whether or not there is movement of a human body or other object in the surroundings. When the non-detection state changes to the detection state, it is assumed that a human body or other object has approached. On the other hand, when the detection state changes to the non-detection state, it is assumed that a human body or other object has moved away.

[0017] As described above, the CPU 110 has the screen control unit 111. This screen control unit 111 controls the display screen 131 so that the screen luminance L of the display screen 131 changes in accordance with changes in brightness detected by the illuminance sensor 140.

[0018] 2, for example, the screen control unit 111 controls the display screen 131 so that, within a predetermined illuminance range (from the lower limit illuminance Emin to the upper limit illuminance Emax), the higher the detected illuminance E, the higher the screen luminance L. However, when the detected illuminance E exceeds the upper limit illuminance Emax, the screen luminance L is controlled to the maximum luminance Lmax, and when the detected illuminance E is below the lower limit illuminance Emin, the screen luminance L is controlled to the minimum luminance Lmin. However, the control is not limited to this.

[0019] The screen control unit 111 controls the display screen 131 so that the first tracking ability, which is the tracking ability of the screen brightness L to changes in brightness when the motion of an object is detected by the moving object detection unit 150, is smaller than the second tracking ability, which is the tracking ability of the screen brightness L to changes in brightness when the motion of an object is not detected.

[0020] Therefore, when movement of an object in the surroundings is detected, the responsiveness of the screen luminance L to changes in the surrounding brightness is suppressed, thereby reducing the discomfort and eye fatigue of the user U that may be caused by a sudden change in the screen luminance L.

[0021] When the moving object detection unit 150 detects the movement of an object and the speed of change in brightness is within a predetermined speed range, the screen control unit 111 may control the display screen 131 so that the first tracking ability is smaller than the second tracking ability. Therefore, when the movement of an object is detected in the surroundings and the surrounding brightness changes gradually, the tracking ability of the screen brightness L to the change in the surrounding brightness becomes smaller. As a result, the discomfort and eye fatigue of the user U caused by a sudden change in the screen brightness L is further reduced.

[0022] The rate of change in brightness is a positive value when the brightness increases, and a negative value when the brightness decreases. The predetermined rate range is assumed to be a range from negative to positive values, with zero in between. For example, the predetermined rate range may be defined as a range in which the absolute value of the rate of change in brightness is equal to or less than a predetermined rate. This is because it is possible to limit the change in brightness to a slow rate, regardless of whether the brightness increases or decreases.

[0023] For example, when the lights in the room are turned off or on while there are no objects, such as a human body, present in the vicinity or the objects are stationary, the detected illuminance E instantaneously or abruptly decreases or increases, and then stabilizes at the value after the change. For example, as shown in the upper left part of FIG. 3, when the detected illuminance E suddenly decreases at time t1, the screen control unit 111 may cause the screen luminance L to follow the change in the detected illuminance E slightly later than in real time, as indicated by the solid line in the lower left part of FIG. 3. Also, when the detected illuminance E suddenly increases at time t2, as shown in the upper right part of FIG. 3, the screen control unit 111 may cause the screen luminance L to follow the change in the detected illuminance E slightly later than in real time, as indicated by the solid line in the lower right part of FIG. 3. Such a tracking ability of the screen luminance L to a change in the detected illuminance E may be referred to as "standard tracking ability" below. Note that this "standard tracking ability" is an example of the "second tracking ability" in the present disclosure.

[0024] The reason why the screen luminance L is not tracked in real time is to prevent the screen luminance L from changing too sensitively depending on the manner of change in the detected illuminance E. Also, this is because the detected illuminance E may fluctuate due to the movement of an object such as a human body. For example, when the movement of an object such as a human body is detected by the moving object detection unit 150, the screen luminance L may be gradually reduced in response to a sudden drop in the detected illuminance E at time t1, as shown by the two-dot chain line in the lower left part of FIG. 3. Similarly, the screen luminance L may be gradually increased in response to a sudden rise in the detected illuminance E at time t2, as shown by the two-dot chain line in the lower right part of FIG. 3. This suppressed tracking of the screen luminance L to changes in the detected illuminance E is an example of the "first tracking" of the present disclosure.

[0025] The moving object detection unit 150 includes, for example, an infrared sensor that detects whether an object is moving. Specific examples include, but are not limited to, a pyroelectric infrared sensor. Therefore, when movement of a surrounding object is detected, the responsiveness of the screen brightness L to changes in the surrounding brightness is suppressed. As a result, discomfort and eye fatigue felt by the user U due to sudden changes in the screen brightness L when an object approaches or passes nearby are reduced.

[0026] However, the moving object detection unit 150 is not limited to an infrared sensor. The moving object detection unit 150 may be, for example, a motion sensor that detects the movement of surrounding objects. The moving object detection unit 150 may be capable of detecting the direction and distance of surrounding objects. Alternatively, the moving object detection unit 150 may have an advanced function of acquiring visible light images or infrared light images, analyzing the images, and accurately detecting the position information and changes of surrounding objects. For example, a stereo camera consisting of two cameras arranged side by side, or a distance image sensor that can acquire distance images having distance information for each pixel using a TOF (Time Of Flight) method may be used, but is not limited to these.

[0027] 2. Operation of the Display Device 100 Next, with reference to Figs. 4 to 8, the operation of the display device 100 in response to various movements of an object such as a human body will be described. Fig. 4 is an explanatory diagram illustrating a case where a user U approaches the display device 100. Fig. 5 is an explanatory diagram illustrating a case where a user U moves away from the display device 100. Fig. 6 is a time chart illustrating the screen luminance L controlled in accordance with changes in the detected illuminance E in the cases of Figs. 4 and 5. Fig. 7A is an explanatory diagram illustrating a case where a human body H temporarily approaches the display device 100. Fig. 7B is an explanatory diagram illustrating a case where the human body H moves away again after Fig. 7A. Fig. 8 is a time chart illustrating the screen luminance L controlled in accordance with changes in the detected illuminance E in the cases of Figs. 7A and 7B.

[0028] 2.1 When user U approaches As shown in Fig. 4, when a user U approaches the display device 100 to operate it (times t3 to t4 in Fig. 6), the shadow cast by the user U gradually becomes darker, and the detected illuminance E detected by the illuminance sensor 140 may also slowly decrease, as shown in the upper and left parts of Fig. 6. At this time, the movement of the user U is detected by the moving object detection unit 150. In other words, the detected illuminance E may decrease due to the movement of the user U.

[0029] Therefore, the screen control unit 111 suppresses the responsiveness of the screen luminance L to changes in the detected illuminance E compared to the responsiveness when the moving object detection unit 150 does not detect any movement of an object.

[0030] The tracking ability may be the ratio of the rate of change of the screen luminance L to the rate of change of the brightness. Therefore, when the movement of an object in the vicinity is detected and the ambient brightness changes slowly, the tracking speed of the screen luminance L to the change in the ambient brightness becomes slow. As a result, the discomfort and eye fatigue of the user U caused by a sudden change in the screen luminance L is further reduced.

[0031] Specifically, the screen control unit 111 may reduce the screen luminance L over approximately twice the time as shown by the solid line in the middle and left sections of Fig. 6, rather than reducing the screen luminance L with a slight delay in response to a decrease in the detected illuminance E, as shown by the two-dot chain line in the middle and left sections of Fig. 6. In other words, the reduction speed is approximately half. However, the reduction speed is not limited to this.

[0032] The tracking ability may be the ratio of the amount of change in the screen luminance L to the amount of change in brightness. Therefore, when movement of an object is detected in the surroundings and the surrounding brightness changes slowly, the amount of tracking of the screen luminance L with respect to the change in the surrounding brightness becomes small. As a result, the discomfort and eye fatigue of the user U caused by unnecessary large changes in the screen luminance L are further reduced.

[0033] Specifically, the screen control unit 111 does not completely adjust the screen luminance L in response to a decrease in the detected illuminance E as shown by the dashed two-dot line in the lower left part of Fig. 6, but instead limits the amount of adjustment to approximately half as shown by the solid line in the lower left part of Fig. 6. However, the amount of adjustment is not limited to this. Furthermore, such reduction in the amount of adjustment may be appropriately combined with the reduction in the speed of adjustment described above.

[0034] 2.2 When user U moves away As shown in Fig. 5, when user U finishes operating display device 100 and moves away (times t5 to t6 in Fig. 6), the shadow cast by user U gradually fades, and the detected illuminance E detected by illuminance sensor 140 may also slowly increase, as shown in the upper and right parts of Fig. 6. At this time, user U, who had been detected by moving object detection unit 150, is no longer detected while the detected illuminance E is increasing.

[0035] In such a case, it is also preferable that the screen control unit 111 suppresses the responsiveness of the screen brightness L to changes in the detected illuminance E more than when the moving object detection unit 150 does not detect any object movement.

[0036] For example, the screen control unit 111 may increase the screen luminance L over approximately twice the time as shown by the solid line in the middle and right of FIG. 6, rather than increasing the screen luminance L with a slight delay in response to an increase in the detected illuminance E, as shown by the two-dot chain line in the middle and right of FIG. 6. In other words, the following speed is approximately half. However, the following speed is not limited to this. Furthermore, the absolute value of the following speed does not necessarily have to be the same as that when the detected illuminance E is decreasing as described above.

[0037] Alternatively, the screen control unit 111 may limit the amount of tracking of the screen brightness L to about half in response to an increase in the detected illuminance E, as shown by the solid line in the lower right part of Fig. 6. As described above, if the amount of tracking is limited to about half when the detected illuminance E decreases, the screen brightness L will eventually return to almost its original state. Furthermore, such suppression of the amount of tracking may be appropriately combined with the suppression of the tracking speed described above.

[0038] 2.3 When a human body H passes in front As shown in Fig. 7A, if a human body H (whether it is user U or not is unclear) approaches display device 100 (times t7 to t8 in Fig. 8), and then, as shown in Fig. 7B, if human body H moves away again (times t9 to t10 in Fig. 8), the shadow cast by human body H may gradually become darker and then gradually become lighter again. As shown in the upper part of Fig. 8, if the detected illuminance E detected by illuminance sensor 140 gradually decreases and then gradually increases again to almost the original level, it is preferable to maintain screen luminance L as it is (solid line in the lower part of Fig. 8) rather than making the screen luminance L follow the change in detected illuminance E (two-dot chain line in the lower part of Fig. 8).

[0039] When controlling the display screen 131 with the first tracking property, the screen control unit 111 does not change the screen luminance L in response to changes in brightness. Therefore, when movement of an object is detected in the surroundings and the surrounding brightness changes gradually, the screen luminance L is maintained even if the surrounding brightness changes. As a result, the discomfort and eye fatigue felt by the user U due to a sudden change in the screen luminance L caused by a temporary change in the surrounding brightness is further reduced.

[0040] However, it is difficult to predict, not only at time t7 but even at time t9, that the detected illuminance E will drop once and then rise again to return to its original state at time t10. Therefore, a delay time, for example, may be set in the control that causes the screen luminance L to follow the change in the detected illuminance E. That is, the screen luminance L may begin to follow the change in the detected illuminance E after a certain time (e.g., several seconds) has elapsed since the change in the detected illuminance E. Furthermore, the above-mentioned control of reducing the following speed or the following amount may also be combined. This makes it possible to suppress fluctuations in the detected illuminance E to some extent, even in cases where the detected illuminance E drops once and then rises again to return to its original state.

[0041] 2.4 Other Cases If none of the above three cases applies, the screen luminance L is made to follow the change in the detected illuminance E with a slight delay from real time, as shown by the solid lines on both the left and right sides in the lower part of FIG.

[0042] 3. Method for controlling screen brightness L by the display device 100 Next, a method for controlling the screen luminance L by the display device 100 will be described with reference to Fig. 9. Fig. 9 is a flowchart showing an outline of the method for controlling the screen luminance L by the display device 100.

[0043] 9, in step S1, the CPU 110 determines whether or not the detected illuminance E has changed. If the detected illuminance E has changed, the process proceeds to the next step S2; if not, the process ends because there is no need to adjust the screen luminance L.

[0044] In step S2, the CPU 110 determines whether or not it has detected the movement of an object such as a human body. If it has detected the movement of an object, it proceeds to the next step S3, and if not, it proceeds to step S6.

[0045] In step S3, CPU 110 determines whether or not there has been a sudden change in detected illuminance E. If there has been a sudden change in detected illuminance E, it is determined that the change is not due to the movement of an object and the process proceeds to step S6; otherwise, the process proceeds to the next step S4.

[0046] In step S4, CPU 110 determines whether the surroundings have darkened slowly, i.e., whether the detected illuminance E has decreased slowly. For example, this determination may be made by comparing the rate of change in detected illuminance E (the amount of change in detected illuminance E per unit time) with a first predetermined rate that has been set in advance. If the surroundings have darkened slowly, the process proceeds to step S8; if not, the process proceeds to the next step S5.

[0047] In step S5, CPU 110 determines whether the surroundings have become brighter slowly, i.e., whether the detected illuminance E has increased slowly. For example, this determination may be made by comparing the rate of change in detected illuminance E with a second predetermined rate that has been set in advance. If the surroundings have become brighter slowly, the process proceeds to step S7; if not, the process proceeds to step S6.

[0048] In step S6, the screen control unit 111 determines that the change in the detected illuminance E is not due to the movement of an object, and sets the tracking ability of the screen luminance L to the standard, thereby completing the series of processes.

[0049] In step S7, as explained in 2(2) above, the screen control unit 111 determines that the human body or the like has moved away, and suppresses the tracking of the screen brightness L. This completes the series of processes.

[0050] In step S8, CPU 110 further determines whether the surroundings gradually became dark and then bright again, that is, whether the detected illuminance E gradually decreased and then increased again. If the determination result is YES, the process proceeds to step S10; otherwise, the process proceeds to step S9.

[0051] In step S9, as explained in 2(1) above, the screen control unit 111 determines that a human body or the like has approached, and suppresses the tracking of the screen brightness L. This completes the series of processes.

[0052] In step S10, as explained in 2(3) above, the screen control unit 111 determines that a human body or the like has passed in front of the screen, and suppresses the tracking of the screen brightness L. This completes the series of processes.

[0053] Note that steps S7, S9, and S10 all suppress the responsiveness of the screen luminance L, but the method and degree of suppression may be different. For example, the degree of suppression in step S7 may be stronger than the degree of suppression in step S9. That is, the responsiveness of the screen luminance L when it gradually brightens may be made more gradual compared to when it gradually darkens. Also, in step S10, the screen luminance L may not be changed even if the detected illuminance E changes. However, this is not a limitation.

[0054] The present invention can be embodied in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely illustrative in all respects and should not be interpreted as limiting. The scope of the present invention is defined by the claims and is not limited to the text of the specification. Furthermore, all modifications and variations within the equivalent range of the claims are within the scope of the present invention. [Industrial Applicability]

[0055] The contents of the present disclosure can be used for display devices. [Explanation of symbols]

[0056] 100 display device 101 Control device 111 Screen control unit 120 Storage section 130 Display section 131 Display screen 140 Illuminance sensor 150 Motion detection unit

Claims

1. a display unit having a display screen; an illuminance sensor that detects the ambient brightness; a moving object detection unit that detects the movement of the surrounding objects; a screen control unit that controls the display screen so that the screen luminance of the display screen changes in accordance with the change in brightness detected by the illuminance sensor; Equipped with A display device in which the screen control unit controls the display screen so that a first tracking ability, which is the tracking ability of the screen brightness to changes in brightness when movement of the object is detected by the motion detection unit, is smaller than a second tracking ability, which is the tracking ability of the screen brightness to changes in brightness when movement of the object is not detected.

2. 2. The display device according to claim 1, wherein the screen control unit controls the display screen so that the first tracking ability is smaller than the second tracking ability when the motion of the object is detected by the moving object detection unit and the rate of change of the brightness is within a predetermined rate range.

3. 3. The display device according to claim 1, wherein the tracking ability is a ratio of a rate of change in the screen luminance to a rate of change in the brightness.

4. 3. The display device according to claim 1, wherein the tracking ability is a ratio of the amount of change in the screen luminance to the amount of change in the brightness.

5. The display device according to claim 1 , wherein the screen control unit, when controlling the display screen with the first tracking property, does not change the screen luminance in response to the change in brightness.

6. 3. The display device according to claim 1, wherein the moving object detector includes an infrared sensor that detects whether or not the object is moving.

Images