WO2022234618A1

WO2022234618A1 - Led display device and display control method

Info

Publication number: WO2022234618A1
Application number: PCT/JP2021/017364
Authority: WO
Inventors: 好功小泉
Original assignee: シャープＮｅｃディスプレイソリューションズ株式会社
Priority date: 2021-05-06
Filing date: 2021-05-06
Publication date: 2022-11-10

Abstract

In the present invention, a display unit has LED elements (10) arranged two-dimensionally, and displays a video by causing the LED elements (10) to sequentially emit light. A light incidence discrimination unit detects a photocurrent flowing through the LED element (10) and discriminates an incident light intensity of the LED element (10). A display control unit sets the luminance value of the LED element (10) on the basis of a result of discriminating the incident light intensity by the light incidence discrimination unit. The display driving unit drives the LED element (10) by controlling the current value of a current driver (13) so that the LED element (10) has the luminance value set by the display control unit.

Description

LED display device and display control method

The present invention relates to an LED display device and a display control method.

LED (Light Emitting Diode) display devices display images by lighting two-dimensionally arranged LED elements, so they can display good images even in bright environments. In addition, by modularizing the display to form a multi-screen, it is possible to realize a large-sized LED display device suitable for various installation locations. LED display devices are widely used, especially in outdoor digital signage, such as on the walls of buildings. Further, Japanese Patent Application Laid-Open No. 2002-200000 proposes a display device that controls the brightness of a display unit according to the amount of ambient light.

Japanese Patent Application Laid-Open No. 2006-030318

When installing the LED display device outdoors, it is desirable to set the brightness appropriately according to the brightness of the surroundings. That is, in the daytime, when the surroundings are bright due to sunlight, it is necessary to increase the brightness of the LED display so that the display can be seen even under strong light. In addition, when the surroundings are dark, if the image is too bright, it becomes difficult to see, so it is necessary to lower the brightness of the LED display.

Also, when an LED display is installed outdoors, there will be a sunny part and a shaded part. Therefore, not only the overall brightness control of the screen but also the partial brightness control on the screen is desired. That is, when an LED display is installed outdoors, there is a possibility that a portion of the screen will be exposed to light due to the influence of sunlight or the like, and a portion of the screen will be dark due to shadows. In that case, if the brightness of the entire screen is set to low to match the shaded area, the image in the shaded area is easy to see on the screen, but the image in the sunny area becomes difficult to see due to the reflected sunlight. Also, if the brightness of the entire screen is set to high in accordance with the sunny area, the image in the sunny area is easy to see, but the image in the shaded area is too bright and difficult to see.

With the technology described in Patent Document 1, brightness is adjusted according to external light detected by a photosensor. With such a configuration, it is difficult to partially control the brightness of the display screen according to the amount of light that partially impinges on the screen.

In view of the above problems, an object of the present invention is to provide an LED display device and a display control method that can partially control the brightness of the display screen according to the amount of light that partially impinges on the screen.

An LED display device according to an aspect of the present invention includes a display unit in which LED elements are arranged two-dimensionally and displays an image by sequentially lighting each LED element; a light incidence determination unit that determines the amount of light incident on the element; a display control unit that sets the luminance value of the LED element based on the determination result of the amount of incident light in the light incidence determination unit; and a display driving unit for driving the LED elements so that the luminance value is the same.

A display control method according to an aspect of the present invention is a display control method for an LED display in which LED elements are arranged two-dimensionally and an image is displayed by sequentially lighting each LED element, wherein a photocurrent flows through the LED elements. is detected to determine the amount of light incident on the LED element; based on the determination result of the amount of incident light, the step of setting the luminance value of the LED element; and driving the LED element.

A program according to an aspect of the present invention causes a computer that performs display control of an LED display, in which LED elements are arranged two-dimensionally and displays an image by sequentially lighting each LED element, to detect photocurrent flowing through the LED elements. determining the amount of light incident on the LED element, setting the brightness value of the LED element based on the determination result of the amount of incident light, and adjusting the brightness value so that the LED element to execute.

According to the present invention, by comparing the voltage of the LED element with the reference voltage and detecting the photocurrent flowing through the LED element, it is possible to determine whether strong light is shining. As a result, the brightness of the display screen can be partially controlled according to the amount of light that partially impinges on the screen.

1 is an explanatory diagram of a principle configuration of an LED display device according to an embodiment of the present invention; FIG. FIG. 4 is a waveform diagram used for explaining the LED display device according to the embodiment of the present invention; FIG. 4 is a waveform diagram used for explaining the LED display device according to the embodiment of the present invention; 1 is an explanatory diagram of an LED display device according to an embodiment of the present invention; FIG. 1 is an explanatory diagram of an LED display device according to an embodiment of the present invention; FIG. 1 is a circuit diagram showing a specific configuration of an LED module according to an embodiment of the invention; FIG. 1 is a block diagram showing the configuration of an LED display device according to an embodiment of the present invention; FIG. 4 is a flow chart showing processing in the display device according to the embodiment of the present invention; 1 is a schematic block diagram showing the basic configuration of an LED display device according to the present invention; FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of the principle configuration of an LED display device according to an embodiment of the present invention. In FIG. 1, an LED element 10 is one of the LED elements forming an LED module of an LED display device. The anode of LED element 10 is connected to scan line 11 . A cathode of the LED element 10 is connected to a current driver 13 .

One end of the scan line 11 is connected to a power supply Vcc1 via a field effect transistor (FET) 12. FET 12 is a switch that selects a scan line. FET 12 is turned on/off by a control signal from terminal 14 .

The current driver 13 sets the current value flowing through the LED element 10 . The current value of this current driver 13 is set by a control signal from terminal 15 .

The operational amplifier 20 compares the voltage of the LED element 10 (voltage at point P1) and the reference voltage (voltage at point P2) to determine light incidence.

Resistors

21 and 22 generate a reference voltage Vth. From the output terminal of the operational amplifier 20, a terminal 23 for determining the light incidence is derived.

In the LED display, an image is displayed on the display by sequentially selecting the two-dimensionally arranged LED elements and turning each LED element on or off according to the image signal. In the configuration shown in FIG. 1, when the LED element 10 is selected, the control signal from the terminal 14 turns on the FET 12 .

While the LED element 10 is selected, the FET 12 is turned on and the current driver 13 is active. When the current driver 13 is active and the FET 12 is turned on, the power supply Vcc1 is applied to the LED element 10 and the LED element 10 is lit. At this time, since the LED element 10 is conducting, the voltage of the LED element 10 becomes the forward voltage Vf.

While the LED element 10 is not selected, the FET 12 is turned off and the current driver 13 is inactive. When the FET 12 is off and the current driver 13 is inactive, the power supply Vcc1 is not applied to the LED element 10 and the LED element 10 is extinguished. The voltage of the LED element 10 at this time changes according to the amount of incident light striking the LED element 10 .

That is, the LED element 10 is basically a PN junction diode. In a PN junction diode, a depletion layer is generated near the PN junction, and current flows when exposed to light. Therefore, if the LED element 10 is exposed to strong light, the voltage of the LED element 10 will be high, and if the light striking the LED element 10 is weak, the voltage of the LED element 10 will be low.

The operational amplifier 20 compares the voltage of the LED element 10 (voltage at point P1) with the reference voltage (voltage at point P2) while the scan line is not selected and the current driver 13 is inactive. , the amount of light incident on the LED element 10 is determined. This determination result is output from the operational amplifier 20 via the terminal 23 . The brightness of the LED element 10 can be set according to the determination result of the amount of incident light from the terminal 23 .

2A and 2B are waveform diagrams used for explaining the LED display device according to the embodiment of the present invention. 2A and 2B, the forward voltage of the LED element 10 is Vf, the voltage of the LED element 10 when the LED element 10 is exposed to strong light is Va1, and the LED element 10 when the light striking the LED element 10 is weak. 10 voltage is Va2. Also, the reference voltage set by the

resistors

21 and 22 is Vth. Also assume that the FET 12 is on and the current driver 13 is active during the period T0, and the FET 12 is off and the current driver 13 is inactive during the period T1.

The LED element 10 is turned on while the FET 12 is on and the current driver 13 is active. Therefore, as shown in FIGS. 2A and 2B, in the period T0, the voltage of the LED element 10 is Vf, which is higher than the reference voltage Vth (Vf>Vth).

While the FET 12 is off and the current driver 13 is inactive, a current flows through the LED element 10 according to the amount of light due to the photoelectric effect. As a result, as shown in FIG. 2A, during period T1, when the LED element 10 is exposed to strong light, the voltage of the LED element 10 is Va1, which is higher than the reference voltage Vth (Va1>Vth). On the other hand, as shown in FIG. 2B, when the light striking the LED element 10 is weak, the voltage of the LED element 10 is Va2 in period T1, which is lower than the reference voltage Vth (Va1<Vth). Therefore, the amount of light incident on the LED element 1 can be determined from the output of the operational amplifier 20 during the period T1.

Thus, the output of the operational amplifier 20 outputs a detection signal indicating whether or not the amount of light impinging on the LED element 10 is large. When it is determined from this detection signal that the amount of light impinging on the LED element 10 is large, the luminance of the LED element 10 can be increased by increasing the current value of the current driver 13 according to the control signal from the terminal 15. - 特許庁Further, when it is determined from the detection signal of the operational amplifier 20 that the amount of light impinging on the LED element 10 is small, the luminance of the LED element 10 is reduced by decreasing the current value of the current driver 13 according to the control signal from the terminal 15. can be lowered.

3 and 4 are explanatory diagrams of the LED display device according to the embodiment of the present invention. As shown in FIG. 3,

RGB LED elements

10, 10, . . . are two-dimensionally arranged on the screen. Here, as shown in FIG. 4, it is assumed that the area AR1 is in the sun and is exposed to strong light, while the area AR2 is in the shade and is not exposed to strong light. As described above, in this embodiment, by comparing the voltages of the

LED elements

10, 10, . In this example, when it is detected that the region AR1 is exposed to strong light, the current values of the

LED elements

10, 10, . . . As a result, when the LED display is placed outdoors, both the image in the shaded area and the image in the sunny area can be clearly displayed.

FIG. 5 is a circuit diagram showing a specific configuration of the LED module 50 according to the embodiment of the invention. In FIG. 5, the LED module 50 is a module that constitutes the screen of the LED display device. Generally, an LED display device installed outdoors has a multi-screen structure in which a plurality of LED modules 50 shown in FIG. 5 are combined.

In this example, the LED module 50 has 32 scan lines 11-1 to 11-32. In addition, n column blocks BL1 to BLn are divided and controlled by n (n is an arbitrary integer) current drivers 13-1 to 13-n.

In FIG. 5, the current drivers 13-1 to 13-n drive the

LED elements

10, 10, . . . of the column blocks BL1 to BLn arranged in the module. As the

LED elements

10, 10, . . . , an SMD (Surface Mount Device) in which RGB LED elements are mounted on a chip can be used. The current drivers 13-1 to 13-n have a data input terminal SDI, a data output terminal SDO, a clock terminal DCLK, a data strobe terminal LE and a gray scale clock terminal GCLK. The brightness level can be set by setting the current value of the LED element 10 by the gray scale clock terminal GCLK.

The FETs 12-1 to 12-32 sequentially select the scan lines 11-1 to 11-32. The

LED elements

10, 10, .

While the FETs 12-1 to 12-32 are off and the current drivers 13-1 to 13-n are inactive, the operational amplifiers 20-1 to 20-32 apply the voltages of the

LED elements

10, 10, . By comparing with , the amount of incident light applied to the

LED elements

10 , 10 , . . . is detected. In this example, it is divided into n column blocks BL1 to BLn by current drivers 13-1 to 13-n. Scan lines 11-1 to 11-32 are sequentially selected by FETs 12-1 to 12-32. The amount of incident light should be detected in the scan lines 11-1 to 11-32 where the FETs 12-1 to 12-32 are off and where the current drivers 13-1 to 13-n are inactive. can be done.

Thus, in the LED module 50 according to the embodiment of the present invention, while the FETs 12-1 to 12-32 are off and the current drivers 13-1 to 13-n are inactive, the

LED elements

10, 10, . By comparing the voltage with the reference voltage, the amount of incident light applied to each

LED element

10, 10, . . . can be detected. As a result, the brightness of the display screen can be partially controlled according to the amount of light that partially impinges on the screen.

FIG. 6 is a block diagram showing the configuration of the LED display device 100 according to the embodiment of the invention. In FIG. 6,

LED elements

10, 10, . As the LED display unit 101, the LED module 50 shown in FIG. 5 can be used.

The light incidence determination unit 102 detects photocurrent flowing through each LED element arranged in the LED display unit 101, and determines whether or not light is incident on each LED element based on the detection result. . That is, as described above, the LED element is basically a PN junction diode. In a PN junction diode, a depletion layer is generated near the PN junction, and current flows when exposed to light. By measuring this photocurrent, light incident on the

LED elements

10, 10, . . . can be detected. As shown in FIG. 5, the light incidence discriminating section 102 can be composed of operational amplifiers 20-1 to 20-32 that compare the voltages of the

LED elements

10, 10, . . . with a reference voltage.

The LED brightness control unit 103 sets the brightness value of each

LED element

10, 10, . . . The LED brightness control unit 103 can be realized by an MPU (Micro Processor Unit) or the like.

The LED display drive section 104 controls the current values of the

LED elements

10, 10, . . . In the configuration shown in FIG. 5, the current drivers 13-1 to 13-n set current values flowing through the

respective LED elements

10, 10, . . . using the grayscale clock terminal GCLK. Thereby, the luminance value of each

LED element

10, 10, . . . is set.

FIG. 7 is a flow chart showing processing in the display device according to the embodiment of the present invention.
(Step S101) Each of the

LED elements

10, 10, .

(Step S102) The light incidence determination unit 102 (operational amplifiers 20-1 to 20-32) determines that the

LED elements

10, 10, are compared with the reference voltage, and it is determined whether or not the voltage of the

LED elements

10, 10, . . . is higher than the reference voltage.

(Step S103) If the voltages of the

LED elements

10, 10, ... are not higher than the reference voltage (Step S102: No), the LED luminance control unit 103 determines that strong light is not applied, and continues the process. Proceed to S104.

(Step S104) The LED brightness control unit 103 maintains the current values of the

LED elements

10, 10, .

(Step S105) If the reference voltage is higher than the voltage of the

LED elements

10, 10, . , the process proceeds to step S106.

(Step S106) The LED brightness control unit 103 sets the brightness value so as to increase the current value of the

LED elements

10, 10, .

(Step S107) The current drivers 13-1 to 13-n control the current value according to the set luminance value, thereby increasing the luminance value of the

LED elements

10, 10, . . . Let

As described above, in the LED display device according to the embodiment of the present invention, the voltage of the

LED elements

10, 10, ... is compared with the reference voltage to detect the photocurrent of the

LED elements

10, 10, ... , whether or not strong light is applied can be determined. As a result, when the LED display is placed outdoors, the brightness can be set according to the shaded area and the sunny area, and a clear image can be displayed.

FIG. 8 is a schematic block diagram showing the basic configuration of an LED display device 500 according to the present invention. An LED display device 500 according to the present invention basically includes a display section 501 , a light incidence determination section 502 , a display control section 503 and a display drive section 504 . The display unit 501 has LED elements arranged two-dimensionally, and displays an image by sequentially turning on each LED element. The light incident determination unit 502 detects the photocurrent flowing through the LED element to determine the amount of light incident on the LED element. The display control unit 503 sets the brightness value of the LED element based on the determination result of the amount of incident light in the light incidence determination unit 502 . The display driving unit 504 drives the LED elements so that the brightness value set in the display control unit 503 is obtained.

All or part of the LED display device 100 in the above-described embodiment may be realized by a computer. In that case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in this recording medium may be read into a computer system and executed. It should be noted that the "computer system" referred to here includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible discs, magneto-optical discs, ROMs and CD-ROMs, and storage devices such as hard discs incorporated in computer systems. Furthermore, "computer-readable recording medium" means a medium that dynamically retains a program for a short period of time, like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. It may also include something that holds the program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client in that case. Further, the program may be for realizing a part of the functions described above, or may be capable of realizing the functions described above in combination with a program already recorded in the computer system. It may be implemented using a programmable logic device such as FPGA.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design within the scope of the gist of the present invention.

REFERENCE SIGNS LIST 10 LED element 101 display section 102 light incidence determination section 103 brightness control section 104 display drive section

Claims

a display unit in which LED elements are arranged two-dimensionally and displays an image by sequentially lighting each LED element;
a light incident determination unit that detects the photocurrent flowing through the LED element and determines the amount of light incident on the LED element;
a display control unit that sets the luminance value of the LED element based on the determination result of the amount of incident light in the light incidence determination unit;
and a display driving section that drives the LED elements so as to achieve the brightness value set in the display control section.
2. The LED display device according to claim 1, wherein the light incidence determination unit compares the voltage of the LED element with a reference voltage to determine the amount of incident light.
The LED display device according to claim 1 or 2, wherein the display driving section sets the luminance value of the LED element according to the current value.
4. The LED display device according to any one of claims 1 to 3, wherein the light incidence determination unit detects photocurrent flowing through the LED elements while the scan line is not selected and the operation is inactive.
A display control method for an LED display in which LED elements are arranged two-dimensionally and an image is displayed by sequentially lighting each LED element,
detecting the photocurrent flowing through the LED element to determine the amount of light incident on the LED element;
setting a luminance value of the LED element based on the determination result of the amount of incident light;
and driving the LED element so as to achieve the set luminance value.
A computer that performs display control of an LED display in which LED elements are arranged two-dimensionally and displays images by sequentially lighting each LED element,
detecting the photocurrent flowing through the LED element to determine the amount of light incident on the LED element;
setting the luminance value of the LED element based on the determination result of the amount of incident light;
driving the LED element so as to achieve the set luminance value;
program to run the