Patent Application
20250157394
The present invention relates to a display system.
As a display device for displaying a video, there has been known a device formed by arranging a large number of self-luminous elements such as light-emitting diodes (LEDs). For example, in JP 2003-005674 A, there is disclosed a technology relating to such an LED display. When self-luminous elements are used, a deep black color can be expressed by completely turning off the self-luminous elements, and hence it may be possible to achieve video display that is superior to that of, for example, a liquid crystal display, which may cause so-called black level degradation.
The present invention has an object to provide a display system capable of excellent video expression.
According to an aspect of the present invention, there is provided a display system including: a display device including a plurality of self-luminous elements; and a control device configured to control an operation of the display device, wherein the control device is configured to cause the display device to: display a normal video through use of gradations of up to luminance equal to or lower than normal maximum luminance; and display a part of a video, as required, through use of a boost light emission in which some of the plurality of self-luminous elements are caused to emit light at luminance exceeding the normal maximum luminance.
According to the present invention, the display system capable of excellent video expression can be provided.
One embodiment of the present disclosure is described with reference to the accompanying drawings. This embodiment relates to a display system for displaying a video. In particular, this embodiment relates to a display system in which, while implementing display without so-called black level degradation through use of self-luminous elements, it is possible to cause self-luminous elements to emit light at high luminance for a limited number of specific pixels to display a video in which, for example, only bright spots are caused to sharply shine.
The display system is based on display in a normal mode of displaying a video through use of gradations of from no light emission to luminance equal to normal maximum luminance. The video displayed in the normal mode is herein referred to as “normal video.” The display system is also configured to be able to display videos in a boost mode of displaying a video by causing the self-luminous elements of some pixels to emit light at luminance exceeding the normal maximum luminance. Causing the self-luminous elements to emit light at luminance exceeding the normal maximum luminance is herein referred to as “boost light emission.” The display system is configured to be able to display a normal video by superimposing the boost light emission thereon.
Conceivable display examples using of the display system according to this embodiment are given below. For example, in displaying of a video of a sunset, only a portion of the sun is displayed at high luminance in the boost mode. In displaying of a video including a lighthouse is displayed, a light of the lighthouse is caused to shine intensely in the boost mode only at a moment at which the light is directed toward spectators. In displaying of a video of a starry sky, only a bright star such as Venus is displayed at high luminance in the boost mode.
In the display system according to this embodiment, the boost light emission is limited by a predetermined rule so as to achieve a predetermined purpose such as to keep an increase in power consumption due to high-luminance display within a predetermined range.
The display device 50 includes self-luminous elements. For example, light emitting diodes (LEDs) may be used as the self-luminous elements. The LEDs may include those using semiconductors and those using organic compounds. For example, one pixel 54 is formed through use of self-luminous elements of three colors, namely, red, green, and blue, and a large number of those pixels 54 are arranged in a display unit 52. The self-luminous elements forming each pixel 54 are not limited thereto, and, for example, may be formed of four colors, namely, red, green, blue, and white, may include a self-luminous element for high luminance and a self-luminous element for low luminance, or may have another combination.
The display unit 52 is based on the display in the normal mode of displaying a normal video through use of gradations of from no light emission to the luminance equal to the normal maximum luminance. The display unit 52 is further configured to be able to operate in the boost mode of displaying a video by subjecting the self-luminous elements of some pixels 54 to the boost light emission at the luminance exceeding the normal maximum luminance.
The display device 50 includes a drive circuit 60 that drives each pixel 54 of the display unit 52. The drive circuit 60 includes a normal drive circuit 61 for the light emission of the self-luminous elements in the normal mode and a high-luminance drive circuit 62 for the boost light emission of the self-luminous elements in the boost mode. The display device 50 includes a control circuit 58 configured to control the drive circuit 60 based on a video signal.
The control device 10 is a computer. The control device 10 includes an integrated circuit such as a CPU, an ASIC, an FPGA, or a GPU, and operates in accordance with a program recorded in, for example, a storage device or the circuit. The control device 10 has functions serving as a video signal acquisition module 11, a boost signal determination module 20, an output signal creation module 13, and a signal output module 15.
The video signal acquisition module 11 acquires a video signal from a video signal providing unit 91 external to the control device 10. The video signal providing unit 91 may be of any type that provides a video signal relating to the video to be displayed on the display device 50. The video signal providing unit 91 may be, for example, a camera, a video reproduction device, or any one of various devices connected through a network.
The boost signal determination module 20 identifies, based on the video signal acquired by the video signal acquisition module 11, a region to be displayed in the boost mode within the video to be displayed on the display device 50, and creates a required signal.
The output signal creation module 13 creates an output signal relating to the video to be displayed on the display device 50 based on the video signal acquired by the video signal acquisition module 11 and the signal in the boost mode created by the boost signal determination module 20. When the boost mode is not used, the above-mentioned video is a video in a general normal mode based on, for example, the video signal acquired from the video signal acquisition module 11. When the boost mode is used, the above-mentioned video is a video in which the video in the normal mode partially includes a high-luminance portion in the boost mode.
The signal output module 15 outputs the output signal created by the output signal creation module 13 to the display device 50. The display device 50 displays a video based on this output signal.
The boost signal determination module 20 includes a boost region identification module 21 and a boost video creation module 22. The boost region identification module 21 determines, based on the video signal acquired from the video signal acquisition module 11, a region of the video to be displayed in the boost mode as a boost region. In this case, a predetermined limitation is applied to the boost region so as to prevent the boost region from becoming too wide. The boost video creation module 22 determines luminance or the like of the self-luminous elements in the boost region based on the boost region identified by the boost region identification module 21, and creates a boost mode video signal.
An outline of an operation of the control device 10 is described.
A configuration of the display device 50 that can display a video in the normal mode and the boost mode is described. Two examples are given below. Those are examples, and other configurations may be used as long as similar functions can be achieved.
For example, in the normal mode, pulse width modulation (PWM) control is performed through use of the first switching element 75 of the low current circuit 72, and hence a normal video in the normal mode can be displayed. At this time, the second switching element 77 is in an off state. In the pixel 54 in the boost mode, PWM control is performed through use of the second switching element 77 of the high current circuit 73, and hence high-luminance display in the boost mode can be performed. In this example, the low current circuit 72 forms a part of the normal drive circuit 61, and the high current circuit 73 forms a part of the high-luminance drive circuit 62. In this case, the maximum luminance at a time of using the low current circuit 72 is set as the normal maximum luminance.
The above-mentioned example is an example in which the low current circuit 72 and the high current circuit 73 are selectively used in the normal mode and the boost mode, but the present invention is not limited thereto. For example, in the normal mode, both the low current circuit 72 and the high current circuit 73 may be utilized to display a video with a high dynamic range. However, in the normal mode, even when the high current circuit 73 is used, the display luminance is limited to luminance equal to or lower than predetermined normal maximum luminance. In this case, in the pixel 54 in the boost mode, a video is displayed at high luminance by performing light emission at high luminance exceeding the normal maximum luminance through use of the high current circuit 73 or through use of the low current circuit 72 and the high current circuit 73.
A power supply voltage to be input to each LED driver 82 can be changed. In this configuration example, a relatively-low-voltage normal power supply 85 and a relatively-high-voltage boost power supply 86 are provided. Each LED driver 82 is connected to the normal power supply 85. In addition, each LED driver 82 is connected to the boost power supply 86 through a switching element 83.
In the normal mode, the LED elements 81 are driven through use of the normal power supply 85 to perform display at normal luminance. In a block including a boost region to be displayed in the boost mode, the LED driver 82 that controls the block is connected to the boost power supply 86 by the switching element 83. As a result, in this block, the LED elements 81 are driven through use of the boost power supply 86, and the display can be performed at high luminance.
In this case, a high voltage is applied to the LED elements 81 for all the pixels 54 in this block, and hence the luminance of the pixels 54 in a region other than the boost region is adjusted to luminance corresponding to normal display by adjusting a luminance command signal level. For example, when a voltage value at a time of using the boost power supply 86 is 100 times larger than that at a time of using the normal power supply 85, the luminance command signal level for the region other than the boost region is adjusted to 1/100. At this time, in the boost region, display at luminance that is 100 times higher than that of the normal display is possible. In this case, gradations are reduced in the region other than the boost region, but in the vicinity of the LED elements 81 emitting light at high luminance, the LED elements 81 that shine at high luminance are so dazzling that there occurs no substantial problem even when the gradations of low luminance are impaired.
In this example, the LED driver 82 operated by the normal power supply 85 forms a part of the normal drive circuit 61, and the LED driver 82 operated by the boost power supply 86 forms a part of the high-luminance drive circuit 62. In this case, the maximum luminance at a time of using the normal power supply 85 is set as the normal maximum luminance.
In the first configuration example illustrated in
An example of a method of identifying the boost region, which is performed in Step S2 by the boost region identification module 21, is described. Three examples are given below. Those are examples, and other methods may be used as long as similar functions can be achieved.
In a first method, the video signal acquisition module 11 acquires two video signals, namely, a main video signal and an auxiliary video signal. The auxiliary video signal is a video signal relating to a video regarding the same object as that of a video relating to the main video signal, the video being acquired under a low exposure condition. The auxiliary video signal is, for example, a signal relating to a video captured by shortening an exposure time or narrowing an aperture. The video of the auxiliary video signal shows only subjects having high luminance, and only high-luminance portions have luminance information. In the first method, a region including luminance information or a region having luminance information exceeding a predetermined value in the auxiliary video signal can be identified as the boost region. The luminance, colors, and the like of the display in the boost mode can be determined based on the auxiliary video signal.
In a second method, the video signal acquisition module 11 acquires one video signal corresponding to the main video signal in the first method. In the second method, the video signal acquisition module 11 identifies the boost region based on the luminance of this video signal. For example, pixels having a luminance value equal to or larger than a predetermined luminance value can be identified based on the video signal, and a region regarding the identified pixels or a part of the region can be identified as the boost region. In addition, the luminance and colors of the display in the boost mode, for example, can be determined based on the area of the region as a whole and the luminance, colors, and the like of a periphery thereof.
A third method is based on the second method, and in addition, an image recognition technology using an artificial intelligence (AI) or the like is used to identify high-luminance subjects such as lights and the sun. A region relating to a luminance subject can be identified as the boost region. In the identification of a high-luminance subject, for example, a portion in which flare peculiar to a highly bright spot is reflected and it is determined to be obvious that the actual object is extremely bright may be identified. The portion identified by the third method may be added to the region identified by the second method, a part of the region identified by the second method may be selected by the third method. In another case, the region identified by the second method and the portion identified by the third method may be respectively given identifiers and handled separately. This method may also be used in combination with the first method.
In the first method, there is a large amount of information, an appropriate boost region can be identified with high accuracy, and sufficient luminance information, color information, and the like can also be obtained, and hence it is possible to perform more satisfactory display. Meanwhile, the first method requires multi-step exposure photography. In the second method and the third method, a normal video format can be used as it is, and special photography is not required.
For various reasons, the boost mode may be required to be used in a suppressed manner. In view of this, in this embodiment, when the boost region is identified as described above, a predetermined limitation is applied. Three examples of this limitation are given. Those are examples, and other methods may be used for the same purpose.
In the boost mode, a larger electric current flows with more power consumption and more heat generation amount than in the normal mode. It is required to design a power supply circuit corresponding to a magnitude of the electric current or the like, and a heat dissipation design corresponding to the heat generation amount is also required. In view of this, in the display system 1 according to this embodiment, the region to which the boost mode is applied is limited as required so that total power consumption and a total heat generation amount are equal to or smaller than a predetermined value.
For example, the area, namely, the number of pixels, of the region in which the display in the boost mode is performed is limited. For example, control can be performed so that a maximum current value in the boost mode is 10 times larger than a maximum current value in the normal mode and the number of pixels to which the boost mode is applied is limited to 10% or smaller of a total number of pixels. With this control, when the maximum current value of each pixel in the normal mode is represented by I and the total number of pixels is represented by N, a maximum value of a total current value is:
I·(1−0.1)N+10I·0.1N=1.9I·N
and is suppressed to 1.9 times larger than a maximum value I·N in the normal mode. Assuming that a maximum number of pixels is not limited, the maximum value of the total current value is 10I·N, which can be 10 times larger than the maximum value in the normal mode, and a power supply circuit design and a heat dissipation design suited to such a maximum value are required. In other words, the display device 50 is designed to be able to cause all the self-luminous elements to simultaneously emit light at the normal maximum luminance, but is not designed to be able to cause all the self-luminous elements to simultaneously emit light at the maximum luminance of the self-luminous elements which is higher than the normal maximum luminance.
The values given herein are examples, and the maximum current value in the boost mode, the maximum number of pixels to which the boost mode is applied, and the like may be set as appropriate depending on the design of the display device 50. For example, in order to display a video of the sun, the luminance may be required to be set 100 times higher in the boost mode than in the normal mode. Even in this case, when the number of pixels to which the boost mode is applied is suppressed to 1% or smaller of the total number of pixels, a maximum value of a total current thereof can be suppressed to be equal to or smaller than two times larger than a maximum value of a total current in the normal mode.
A bright spot being wide and dazzling may hinder viewing, and hence even in consideration thereof, the maximum value of the total current at a time of using the boost mode may be suppressed to be equal to or smaller than about 1.5 to about 2.5 times larger than the maximum value of the total current in the normal mode.
The boost region identification module 21 identifies the boost region while limiting the boost region so that the number of pixels to which the boost mode is to be applied is equal to or smaller than a preset maximum number of applicable pixels. For example, a condition for identifying the boost region is changed so that the number of pixels in the boost region is equal to or smaller than the maximum number of applicable pixels. For example, in the above-mentioned first method regarding the identification of the boost region, the exposure condition for obtaining the video of an auxiliary video signal by photography can be changed so that the number of pixels in the boost region is equal to or smaller than the maximum number of applicable pixels. Further, for example, in the second method, a threshold value for luminance can be set so that the number of pixels in the boost region is equal to or smaller than the maximum number of applicable pixels. When a high-luminance region in the video is too wide to limit the number of pixels in the boost region to be equal to or smaller than the maximum number of applicable pixels, the boost mode is not required to be used.
In another case, after a boost candidate region that is a candidate for the boost region is first determined under a predetermined condition, pixels to which the boost mode is to be applied may be selected from within the boost candidate region. For example, in the above-mentioned first method regarding the identification of the boost region, the video of an auxiliary video signal is obtained by photography under a predetermined low exposure condition, and the boost candidate region may be determined based on this auxiliary video signal. For example, when the number of pixels in the boost candidate region is equal to or smaller than the maximum number of applicable pixels, the boost mode is applied to all the pixels in the boost candidate region. When the number of pixels in the boost candidate region exceeds the maximum number of applicable pixels, pixels having high priority, for example, pixels the number of which is equal to or smaller than the maximum number of applicable pixels in descending order of the luminance value may be selected as the pixels to which the boost mode is to be applied. In another case, pixels in a whole region representing a bright spot including a pixel having the highest luminance value are selected as the pixels to which the boost mode is to be applied, and subsequently in the same manner, pixels in regions representing bright spots including pixels having higher luminance values may be selected as the pixels to which the boost mode is to be applied in order until the maximum number of applicable pixels is reached. In another case, depending on a type of a bright spot identified from a video, the pixels to which the boost mode is to be applied may be selected, for example, with priority being given to natural objects over artificial objects, or vice versa. In another case, when the number of pixels in the boost candidate region is too large to identify the order of priority, no pixels may be selected as the pixels to which the boost mode is to be applied, and the boost mode is not required to be used.
The following operation may be performed for the purpose of suppressing the total power consumption in the same manner as in the first limitation method. In the first limitation method, the limitation is performed in terms of the number of pixels so that the number of pixels to which the boost mode is to be applied is limited to be equal to or smaller than the maximum number of applicable pixels, while in a second limitation method, the limitation may be performed based on the total power consumption. That is, a total sum of products of the luminance in the boost mode and the number of pixels therefor may be limited to be equal to or smaller than a predetermined value. For example, the boost region may be identified in a suppressed manner so that the sum is equal to or smaller than a predetermined value. In another case, while all pixels that can be included in the boost region are set as the pixels to which the boost mode is to be applied, the luminance of each of the pixels to which the boost mode is to be applied may be suppressed so that the total sum is equal to or smaller than a predetermined value.
The light emission in the boost mode may shorten a life of the self-luminous element. In view of this, the use of the boost mode can be limited so that each self-luminous element cannot continuously emit light in the boost mode for a predetermined time period or longer. In addition, a cumulative time period of the light emission of each self-luminous element in the boost mode can be managed, and when the cumulative time period exceeds a predetermined cumulative time period, the use of the boost mode can be limited.
For example, the condition for identifying the boost region may be set stricter when a continuous light-emitting time period or a cumulative light-emitting time period in the boost mode exceeds a predetermined value. In addition, when the continuous light-emitting time period or the cumulative light-emitting time period in the boost mode exceeds the predetermined value, the boost mode is not required to be applied to pixels relevant thereto. Further, when an object the area of which is small, such as a particularly bright star, is displayed, use of the pixels each having the continuous light-emitting time period or the cumulative light-emitting time period in the boost mode exceeding the predetermined value may be avoided to perform the display in the boost mode through use of other neighboring pixels, irrespective of occurrence of some positional displacement. In another case, when the display of the same video continues for a long period of time, the display in the boost mode may be performed while pixels for use are periodically shifted slightly so as to prevent the continuous light-emitting time period or the cumulative light-emitting time period in the boost mode from exceeding the predetermined value.
For example, in a case of flickering light such as light from a twinkling star or rotating light from a lighthouse, the continuous light-emitting time period or the cumulative light-emitting time period may be managed through use of average luminance, namely, an average electric current, within a certain period of time.
A relationship between the video signal acquired by the video signal acquisition module 11 and the output signal created by the output signal creation module 13 is described.
When the video signal acquired by the video signal acquisition module 11 is computer graphics (CG), the video signal may be created with the use of the boost mode being assumed in advance. For general display (display in the normal mode only), flare is often drawn to express that a high-luminance bright spot has high luminance. Meanwhile, when the display system 1 according to this embodiment is used, it suffices to include data for designating a spot having high luminance in the video signal without drawing flare.
In the processing step of Step S3, the boost video creation module 22 creates a boost mode video signal, which is a video signal of only high-luminance spots that uses the boost mode. In the processing step of Step S4, the output signal creation module 13 creates a video signal that is obtained by excluding the high-luminance spots from the video signal acquired by the video signal acquisition module 11 and conforms to the configuration of the display device 50. The output signal creation module 13 outputs this video signal as a first-line video signal to the display device 50 through the signal output module 15. The first-line video signal is, for example, a video signal of 8, 10, 12, or 16 bits for each color. In addition, the output signal creation module 13 uses the boost mode video signal created by the boost video creation module 22 to create a video signal conforming to the configuration of the display device 50. The output signal creation module 13 outputs this video signal as a second-line video signal to the display device 50 through the signal output module 15. The second-line video signal may be, for example, a video signal of 8, 10, 12, or 16 bits for each color, or a video signal having a smaller number of bits.
The display device 50, which has acquired the two-line video signals, displays a normal video by an operation in the normal mode based on the first-line video signal, and displays a video by an operation in the boost mode based on the second-line video signal. For example, the control circuit 58 of the display device 50 refers to a look-up table (LUT) with the first-line video signal being used as input to convert the first-line video signal into a pulse width value. The control circuit 58 inputs this pulse width value to the normal drive circuit 61, and the normal drive circuit 61 drives the display unit 52. The control circuit 58 also refers to the look-up table (LUT) with the second-line video signal being used as input to convert the second-line video signal into a pulse width value. The control circuit 58 inputs this pulse width value to the high-luminance drive circuit 62, and the high-luminance drive circuit 62 drives the display unit 52. As a result, the display device 50 displays a video in which only the high-luminance spots are brightened in the boost mode in addition to the normal video displayed in the normal mode.
For example, when the display device 50 includes the first configuration example described with reference to
For example, when the display device 50 includes the second configuration example described with reference to
When the video signal acquired by the video signal acquisition module 11 is a video signal relating to a real-world scene and includes such a main video signal as shown in
In this case, in the video of the main video signal, flare may be reflected in a periphery of a high-luminance spot. The output signal creation module 13 is preferred to perform image processing for suppressing flare resulting from such a high-luminance subject through use of information on the identified high-luminance spot. For example, it is possible to suppress flare by subjecting the video of the main video signal to processing for applying a predetermined blur (shading) or subtraction processing. The output signal creation module 13 outputs the video signal created in this manner as the first-line video signal to the display device 50 through the signal output module 15. In addition, the output signal creation module 13 creates a video signal conforming to the configuration of the display device 50 through use of the boost mode video signal created by the boost video creation module 22. The output signal creation module 13 outputs this video signal as the second-line video signal to the display device 50 through the signal output module 15. The display device 50, which has acquired the two-line video signals, displays the normal video by the operation in the normal mode based on the first-line video signal, and also displays the video by the operation in the boost mode based on the second-line video signal.
Even when the video signal acquired by the video signal acquisition module 11 is a video signal relating to a real-world scene and includes only a main video signal and no auxiliary video signal, the method is basically the same as that described above except for the method of creating a boost mode video signal. In this case, the boost mode video signal can be created based on the main video signal.
In the above-mentioned embodiment, the example in which all the self-luminous elements can emit light at the luminance exceeding the normal maximum luminance and the respective self-luminous elements display the video in the normal mode or display the video in the boost mode has been given, but the present invention is not limited thereto. All the self-luminous elements may be able to emit light at the luminance equal to or lower than the normal maximum luminance, and at least one of the self-luminous elements may be able to perform the boost light emission at the luminance exceeding the normal maximum luminance. In this case, the video display in the boost mode is performed through use of only the self-luminous elements capable of the boost light emission. Further, the display device 50 may be configured such that each self-luminous element for the normal mode, which emits light at the luminance equal to or lower than the normal maximum luminance, and each self-luminous element for the boost mode, which performs the boost light emission, are different elements and videos are displayed in the normal mode and the boost mode through use of the different self-luminous elements.
According to the display system 1, self-luminous elements are used in the display device 50, and hence it is possible to display a video without black level degradation by completely turning off the self-luminous elements in a black portion. This contrasts with a case of, for example, a liquid crystal display using a backlight, which cannot completely block light. In addition, through the application of the boost mode, the display system 1 can cause bright spots to sharply shine in black display without black level degradation. Under a state in which the boost mode is not applied, appropriate video expression is obtained as in the related art, and the boost mode is used to display sharply shining bright spots on top of the video expression, to thereby be able to achieve video expression that has never existed in the related art.
Further, problems that additional power consumption and additional heat generation occur due to the boost mode are resolved by limiting the pixels to which the boost mode is to be applied, thereby suppressing the additional power consumption and heat generation within certain ranges.
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the embodiment described above. Needless to say, various modifications may be made within the scope of the present invention.
The documents described in the specification and the specification of Japanese application on the basis of which the present application claims Paris convention priority are incorporated herein by reference in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-016279 | Feb 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/003527 | 2/3/2023 | WO |
