JPH08250278A - Led display apparatus - Google Patents

Abstract

PURPOSE: To prevent flicker of an LED by comparing the brightness in the surrounding detected by an illuminance detecting apparatus and the brightness of an LED display screen detected by a brightness detecting apparatus and controlling the LED in the way the difference of the brightness becomes the same as a set value. CONSTITUTION: A brightness in the surrounding of an LED display screen 1 and the brightness of the LED display screen 1 are at first set. Then, the brightness of the surrounding of the screen 1 is detected by an illuminance meter 3 and an A/D converter 5 installed in the LED display apparatus main body 2 and whether the difference between the detected value and the brightness 6 of the screen 1 is the same as the brightness difference set value 9 or not is judged. In the case both are found equal as a result, the brightness of the display screen 1 is kept as is and the brightness is sent out as a brightness signal 13 of the LED. On the other hand, in the case both are not equal, whether the difference of the detected value is higher than the brightness difference set value 9 or not is judged. In the case the brightness difference is found higher than the brightness difference set value 9 as a result, a brightness signal 13 of the LED is so sent out as to heighten the brightness of the screen. Meanwhile, in the case the difference is found smaller than the set value 9, the brightness is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED display device, and more particularly to an LED display device in which an image is easy to see and there are few failures.

[0002]

2. Description of the Related Art Recently, LED display devices have been widely used as display devices for displaying various screens in various fields. By the way, in the conventional LED display device, the brightness of the LED display screen cannot be changed depending on the brightness around the LED display screen. Also LED
The brightness of the LED display screen cannot be changed depending on the internal temperature of the display device.

Therefore, in the conventional LED display device as described above, the brightness of the LED display screen does not change due to the brightness of the surroundings. Therefore, when the surroundings of the LED display screen are bright, the brightness of the image on the LED display screen is high. It becomes very difficult to see when it is dark.

Further, since the brightness of the LED display screen does not change depending on the internal temperature of the LED display device, if the internal temperature becomes high during the image display of the LED display screen, the LED and internal equipment may be damaged. It may be very disadvantageous in terms of reliability as a display device.

[0005]

As described above, in the conventional LED display device, if the periphery of the LED display screen is bright, it is difficult to see the image, or if the internal temperature becomes high, the LED and the internal equipment may be damaged. There was a problem of fear.

An object of the present invention is to provide an LED even when the brightness is lowered due to the deterioration of the LED or when the temperature is lowered at the time of startup.
An object of the present invention is to provide an LED display device capable of making an image on a display screen easy to see.

It is another object of the present invention to prevent the failure of the LED display screen by lowering the brightness of the LED display screen to lower the internal temperature when the temperature inside the device is high, thereby protecting the built-in equipment and extending the life of the device. It is to provide a small number of LED display devices.

[0008]

In order to achieve the above object, first, an LED display device of the invention according to claim 1 is an LED display device main body having an LED display screen, and L
An illuminance detection unit attached to the main body of the ED display device for detecting the ambient brightness of the LED display screen, a brightness detection unit for detecting the brightness of the LED display screen, and an ambient brightness and brightness detection by the illuminance detection unit. Based on the comparison means for comparing the brightness of the LED display screen detected by the means and the brightness difference which is the comparison result by the comparison means, L is set so that the brightness difference becomes equal to the preset value.
And a control means for outputting a luminance signal to adjust the luminance of the ED display screen.

An LED display device according to a second aspect of the present invention is an LED display device main body having an LED display screen, temperature detecting means attached to the LED display device main body for detecting the internal temperature thereof, and temperature detection. Comparison means for comparing the internal temperature of the device detected by the means with a preset value, and the comparison result by the comparing means, so as to reduce the brightness of the LED display screen when the internal temperature of the equipment rises above the set value. And a control means for controlling.

On the other hand, an LED display device according to a third aspect of the present invention is an LED display device main body having an LED display screen, and an illuminance detection device attached to the LED display device main body for detecting the brightness around the LED display screen. And a control unit that outputs a brightness signal so as to change the brightness of the LED display screen according to the ambient brightness detected by the illuminance detection unit.

An LED display device according to a fourth aspect of the present invention is the LED display device according to the first or third aspect of the invention, which is attached to the LED display device body and detects the internal temperature thereof. A temperature detection means and a control means for outputting a brightness reduction signal to the brightness signal in order to reduce the brightness of the LED display screen according to the internal temperature of the device detected by the temperature detection means are additionally provided.

Furthermore, the LED of the invention corresponding to claim 5
The display device is, in the LED display device according to any one of claims 1, 3, and 4, a delay unit that delays an illuminance signal output from the illuminance detection unit for a predetermined time, Comparing means for comparing the level value of the illuminance signal delayed by this delay means and the current illuminance signal,
Based on the value compared by the comparing means, a change amount detecting means for detecting the change amount of the illuminance signal and the change amount of the illuminance signal detected by the change amount detecting means are compared with a preset value. If the change amount is larger than the set value, the delay value is output, and if the change amount is smaller than the set value, the current value is output.

[0013]

Therefore, in the LED display device of the invention according to claim 1, the brightness of the LED display screen is controlled according to the brightness around the LED display screen, that is, the brightness around the LED display screen and the LED display. By controlling the difference from the screen brightness to be constant, it is possible to make the image on the LED display screen easy to see even when the brightness is decreased due to deterioration of the LED or when the temperature is decreased at startup.

Further, in the LED display device of the invention according to claim 2, the brightness of the LED display screen is controlled according to the internal temperature of the LED display device main body, that is, the internal temperature of the device is constantly monitored to be equal to or more than a set value LED when rising to
By lowering the brightness of the display screen, when the temperature inside the device is high, the brightness of the LED display screen is lowered to lower the internal temperature, and the built-in equipment can be protected and the life of the device can be extended.

On the other hand, in the LED display device of the invention according to claim 3, the brightness of the LED display screen is changed according to the ambient brightness of the LED display screen, so that the LED display screen has a simple structure. L according to the ambient brightness
The brightness signal of the ED display screen can be switched.

Further, in the LED display device of the invention according to claim 4, the same operation as that of the LED display device of the invention according to claim 1 or 3 can be obtained.
By reducing the brightness of the LED display screen according to the temperature inside the device of the LED display screen, even when the brightness around the LED display screen is bright and the temperature inside the device is high,
It is possible to protect the built-in equipment by reducing the brightness of the LED display screen and lowering the internal temperature.

Further, the LED of the invention corresponding to claim 5
In the display device, the same operation as the LED display device of the invention corresponding to claim 1 or claim 3 or claim 4 is obtained, and the difference between the delay value obtained by delaying the illuminance signal for a certain time and the current value. However, if it is larger than the set value, the delay value is
When the value is smaller than the set value, the current value is set as the illuminance signal, so that the output value of the illuminance detecting means is smoothed even when the brightness around the LED display screen changes frequently. It can prevent flickering.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is an external perspective view showing a structural example of an LED display device according to this embodiment.

In FIG. 1, an LED display device main body 2 having an LED display screen 1 is provided with an illuminance meter 3 which is an illuminance detecting means for detecting the brightness around the LED display screen 1.

FIG. 2 is a block diagram showing a detailed configuration example of the control device section in the LED display device. In FIG. 2, the brightness 4 around the LED display screen 1 is detected by the illuminance meter 3 and converted into a digital amount by the A / D converter 5.

In the present embodiment, the control structure is shown digitally, but analog control is also possible. The brightness 6 of the LED display screen is detected by the brightness detector 7. In this case, as a detection method, for example, LE
Since the current value consumed by D is proportional to the brightness of the LED, the brightness of the LED display screen is detected from the current consumed by the LED.

On the other hand, the difference between the output from the A / D converter 5 and the output from the luminance detector 7 is taken by the comparator 8, and the comparison signal from the comparator 8 is inputted to the luminance difference set value which is inputted in advance. 9 and the comparator 10, and the comparison signal from the comparator 10 is input to the control calculation unit 11.

Then, the control signal obtained as a result of the control calculation in the control calculation unit 11 is input to the brightness signal amplification unit 12 and amplified, and the brightness signal 13 of the LED is output to determine the brightness 6 of the LED display screen. adjust.

The output signal from the luminance signal amplifier 12 is compared with the comparison signal from the comparator 8 by the comparator 14, and the comparison signal from the comparator 13 is compared with the comparator 10.
To enter.

Next, L of the present embodiment constructed as described above
The operation of the ED display device will be described with reference to the flowchart shown in FIG. In FIG. 3, first, the difference (luminance difference) between the brightness around the LED display screen 1 and the luminance of the LED display screen 1 is set (step S1).

Next, the ambient brightness of the LED display screen 1 is detected by the illuminance meter 3 attached to the LED display body 2 and the A / D converter 5 (step S2), and the detected value and the LED are detected. It is determined whether or not the difference between the brightness 6 of the display screen 1 and the detected value (step S3) is equal to the brightness difference setting value 9 (step S4).

As a result, when they are equal, the LED
A command for holding the brightness of the display screen 1 as it is (step S5) is output as the brightness signal 13 of the LED (step S6).

On the other hand, if they are not equal, it is further determined whether or not the difference between the detected values is larger than the brightness difference setting value 9 (step S7). As a result, when the brightness difference setting value is larger than 9, the LED brightness signal 13 is output (step S6) so as to increase the brightness of the LED display screen 1 (step S8).

When the brightness difference setting value is smaller than 9, the brightness of the LED display screen 1 is lowered (step S9).
To output the LED brightness signal 13 (step S6)
To do.

The difference between the detected values is the brightness difference set value 9
The brightness of the LED display screen 1 is controlled so as to be substantially equal to. As described above, in the LED display device of this embodiment, the brightness 4 around the LED display screen 1 and the brightness 6 of the LED display screen 1 are detected, and the difference between them is compared with the brightness difference setting value 9. , If the difference between the two is larger than the set value,
The brightness of the LED display screen 1 is increased, and when the difference between the two is smaller than the set value, the brightness of the LED display screen 1 is decreased. It is possible to always keep the difference with the luminance of the.

Further, since the brightness 6 of the LED display screen 1 is always detected, even when the brightness is lowered due to the deterioration of the LED over time, the difference between the brightness of the surroundings of the LED display screen 1 is constant. Can be In addition, when the temperature when starting up the LED display device is low,
It is also possible to prevent the brightness of the LED display screen 1 from becoming too bright as compared with the surrounding brightness.

As described above, it becomes possible to make the image on the LED display screen 1 easy to see even when the brightness is lowered due to the deterioration of the LED or the temperature is lowered at the time of start-up. [Second Embodiment] FIG. 4 is an external perspective view showing a structural example of an LED display device according to this embodiment, and the same elements as those in FIGS. 1 and 2 are designated by the same reference numerals.

In FIG. 4, the LED display main body 2 having the LED display screen 1 is provided with a thermometer 15 which is a temperature detecting means for detecting the internal temperature thereof. FIG. 5 is a block diagram showing a detailed configuration example of a control device section in the LED display device, and the same elements as those in FIGS. 1 and 2 are denoted by the same reference numerals.

In FIG. 5, the device internal temperature set value 16 is input to the control device. In addition, the thermometer 15 allows LE
The internal temperature of the D display device body 2 is detected and converted into a digital value by the A / D converter 17.

In this embodiment, the control structure is digital, but analog control is also possible. Further, although the device internal temperature set value 16 is set in advance, it is also possible to perform control to detect the device internal temperature and output a brightness signal corresponding to the internal temperature.

On the other hand, the difference between the output from the A / D converter 17 and the device internal temperature set value 16 is taken by the comparator 18, and the comparison signal from the comparator 18 is inputted to the control calculation unit 19.
Then, the control signal obtained as a result of the control calculation in the control calculation unit 19 is input to the luminance signal amplification unit 20 to be amplified and LE
The D luminance signal 21 is output and displayed on the LED 22.

Next, L of the present embodiment configured as described above.
The operation of the ED display device will be described with reference to the flowchart shown in FIG. In FIG. 6, first, the apparatus internal temperature is set (step S1).

Next, the device internal temperature is detected by the thermometer 15 and the A / D converter 17 attached to the LED display device body 1 (step S2), and the detected value and the device internal temperature set value 16 are combined. Compare the magnitude relationship (step S
3).

As a result, when the detected value is larger than the device internal temperature set value 16, the LED brightness signal 21 is output (step S5) so as to reduce the brightness of the LED display screen (step S4). Also, in other cases,
The brightness signal 21 of the LED is output as it is (step S5)
To do. Then, the brightness of the LED display screen 1 is controlled so that the internal temperature of the LED display device body 1 does not exceed the device internal temperature set value 16.

As described above, in the LED display device of this embodiment, the internal temperature of the LED display device body 1 is detected,
This detected value is compared with the device internal temperature set value 16, and when the temperature is higher than the device internal temperature set value 16, the brightness of the LED display screen 1 is lowered to constantly adjust the internal temperature of the LED display device main body 1 to the device. It can be lower than the internal temperature set value 16.

Further, since the internal temperature of the LED display device body 1 is detected, it is possible to quickly control even when the internal temperature of the device suddenly rises. From the above, when the temperature inside the device is high, the LED display screen 1
It is possible to reduce the brightness of the device, reduce the internal temperature, protect the built-in equipment, and prolong the life of the device, and reduce the device failure.

[Third Embodiment] FIG. 7 is a block diagram showing a detailed configuration example of the control unit in the LED display device according to the present embodiment. The same elements as those in FIGS. 1 and 2 are designated by the same reference numerals. It is attached.

In FIG. 7, the brightness 4 around the LED display screen 1 is detected by the illuminance meter 3 attached to the LED display device main body 1 and converted into a digital quantity by the A / D converter 5.

In the present embodiment, the control structure is shown digitally, but analog control is also possible. On the other hand, the output signal from the A / D converter 5 is input to the control calculation unit 23.

Then, the control signal obtained as a result of the control calculation in the control calculation unit 23 is input to the luminance signal amplification unit 24 and amplified, and L corresponding to the ambient brightness of the LED display screen 1 is obtained.
The ED brightness signal is output and displayed on the LED 25.

As described above, in the LED display device of the present embodiment, according to the ambient brightness 4 of the LED display screen 1,
Since the brightness of the LED display screen 1 is changed, the brightness signal of the LED display screen 1 can be switched according to the brightness around the LED display screen 1 with a simple configuration.

As described above, it becomes possible to make the image on the LED display screen 1 easy to see even when the brightness is lowered due to the deterioration of the LED or the temperature is lowered at the time of starting. [Fourth Embodiment] FIG. 8 is an external perspective view showing a structural example of an LED display device according to the present embodiment.
The same elements as those in FIGS. 4 and 5 are designated by the same reference numerals.

In FIG. 8, the illuminance meter 3 for detecting the brightness around the LED display screen 1 is attached to the LED display device body 2 having the LED display screen 1, and L
A thermometer 15 for detecting the internal temperature of the ED display device body 2 is attached.

FIG. 9 is a block diagram showing a detailed configuration example of the control device section in the LED display device. In the control device section of this embodiment, the following elements are added to the LED display device of the first or third embodiment.

That is, in FIG. 9, the internal temperature 26 of the LED display device main body 1 is detected by the thermometer 15 and input to the control calculation unit 27. Further, by the control calculation unit 27,
The brightness decrease signal 28, which is the brightness decrease amount corresponding to the device internal temperature 26, is calculated, and the brightness reduction signal 28 is calculated according to the first embodiment or the third embodiment.
The difference between the luminance signal and the luminance reduction signal 28 in the above embodiment is taken by the comparator 29 and output to the LED.

When the brightness around the LED display screen 1 is becoming brighter, the brightness of the LED display screen 1 also increases in accordance with the surrounding brightness, and the internal temperature 26 of the apparatus also rises.

Therefore, the brightness decrease signal 28 controls the brightness of the LED display screen 1 so as not to exceed the temperature limit value. As described above, in the LED display device according to the present embodiment, the LED display device 1 is operated according to the internal temperature of the LED display screen 1.
Since the brightness of the display screen 1 is reduced, the same effect as in the case of the first or third embodiment can be obtained, and the brightness around the LED display screen 1 is bright and the temperature inside the device is high. Even when the temperature is high, it is possible to reduce the brightness of the LED display screen 1 and lower the internal temperature to protect the built-in device.

[Fifth Embodiment] FIG. 10 is a block diagram showing a detailed configuration example of a control unit in the LED display device according to the present embodiment. In the control device section of the present embodiment, the following elements are added to the LED display device of the first, third or fourth embodiment.

That is, in FIG. 10, the comparator 31 compares the level of the delay value obtained by delaying the illuminance signal of the LED display screen 1 by the delay unit 30 for a certain period of time with the current value of the illuminance signal, and the change amount detector 32. To enter.

Further, the change amount detector 32 detects the change amount per unit time and outputs the output thereof.
To enter. Further, in the change amount setting unit 33, the change amount of the illuminance signal is preset, and if the difference between the current value of the illuminance signal and the delay value is larger than the preset set value, the delay value If it is smaller than the set value, the current value is output to each control calculation unit.

As described above, in the LED display device according to the present embodiment, when the difference between the delay value obtained by delaying the illuminance signal for a fixed time and the current value of the illuminance signal is larger than the set value, the delay value is When the value is smaller than the set value, the current value is set as the illuminance signal.
Alternatively, the same effect as in the case of the fourth embodiment can be obtained,
Since the brightness of the LED changes depending on the surrounding brightness, L
Even when the surrounding brightness of the ED display screen 1 frequently changes, the output value of the illuminance meter 3 can be smoothed to prevent the LED from flickering.

The present invention is not limited to the above embodiments, but can be implemented in the same manner as described below. In each of the above embodiments, as another method for detecting the brightness of the LED display screen 1, for example, an illuminance meter different from the illuminance meter 3 is newly attached on the front surface of the LED display screen 1 to Detect brightness. Then, the lighting area is calculated from the lit dots of the LED at this time, and the brightness of the LED display screen 1 is detected from the ratio between the output value of the separately installed illuminometer and the lighting area. Good.

[0058]

As described above, according to the invention corresponding to claim 1, the LED display device main body having the LED display screen, and the LED display device main body attached to the LED display device main body
An illuminance detecting means for detecting the brightness around the display screen;
The brightness detection means for detecting the brightness of the ED display screen, the comparison means for comparing the ambient brightness detected by the illuminance detection means with the brightness of the LED display screen detected by the brightness detection means, and the comparison result by the comparison means. Based on a certain brightness difference, a control means for outputting a brightness signal to adjust the brightness of the LED display screen so that the brightness difference becomes equal to a preset value is provided.
It is possible to provide an LED display device capable of making the image on the LED display screen easy to see even when the brightness is lowered due to the deterioration of D or the temperature is lowered at the time of startup.

According to the invention corresponding to claim 2,
LED display device main body having LED display screen, and LED
A temperature detecting means attached to the display device body for detecting the internal temperature thereof, a comparing means for comparing the internal temperature of the device detected by the temperature detecting means with a preset value, a comparison result by the comparing means, and an apparatus Since the control means for adjusting the brightness of the LED display screen to decrease when the internal temperature rises above the set value is provided, when the internal temperature of the device is high, the brightness of the LED display screen is reduced to reduce the internal temperature. It is possible to provide an LED display device which has a reduced number of malfunctions and which can be lowered and protect the built-in equipment to extend the life of the device.

On the other hand, according to the invention corresponding to claim 3,
LED display device main body having LED display screen, and LED
An illuminance detection unit that is attached to the display device main body and detects the ambient brightness of the LED display screen, and a brightness signal that changes the brightness of the LED display screen according to the ambient brightness detected by the illuminance detection unit. Since it is provided with the control means for outputting, the LED display device capable of switching the luminance signal of the LED display screen according to the ambient brightness of the LED display screen can be provided with a simple configuration.

According to the invention corresponding to claim 4,
In the LED display device of the invention corresponding to claim 1 or claim 3, the LED display device is attached to a main body,
Temperature detecting means for detecting the internal temperature and control means for outputting a brightness decrease signal to the brightness signal in order to decrease the brightness of the LED display screen according to the internal temperature of the device detected by the temperature detecting means. Since it is added, even when the brightness around the LED display screen is bright and the temperature inside the device is high, it is possible to reduce the brightness of the LED display screen and lower the internal temperature to protect the internal device. An LED display device with few failures can be provided.

Furthermore, according to the invention corresponding to claim 5, in the LED display device of the invention corresponding to any one of claims 1, 3, and 4, the output from the illuminance detecting means is used. A delay means for delaying a certain illuminance signal for a fixed time, a comparing means for comparing the level value of the illuminance signal delayed by the delay means and the current illuminance signal, and an illuminance signal based on the value compared by the comparing means. Change amount detecting means for detecting the change amount of the illuminance signal and the change amount of the illuminance signal detected by the change amount detecting means are compared with a preset set value, and when the change amount is larger than the set value, the delay value Since the change amount setting means for outputting the current value when the change amount is smaller than the set value is added, even when the ambient brightness of the LED display screen changes frequently, Teru To smooth the output value of the detection means, capable of preventing the LED flickering LED
A display device can be provided.

[Brief description of drawings]

FIG. 1 is an external perspective view showing a configuration example of an LED display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration example of a control device section in the LED display device of the first embodiment.

FIG. 3 is a flowchart for explaining the operation of the LED display device of the first embodiment.

FIG. 4 is an external perspective view showing a configuration example of an LED display device according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a detailed configuration example of a control device section in the LED display device of the second embodiment.

FIG. 6 is a flowchart for explaining the operation of the LED display device according to the second embodiment.

FIG. 7 is a block diagram showing a detailed configuration example of a control unit in an LED display device according to a third embodiment of the present invention.

FIG. 8 is an external perspective view showing a configuration example of an LED display device according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a detailed configuration example of a control unit in the LED display device according to the fourth embodiment.

FIG. 10 is a block diagram showing a detailed configuration example of a control unit in an LED display device according to a fifth embodiment of the present invention.

[Explanation of symbols]

 1 ... LED display screen, 2 ... LED display device main body, 3 ... illuminance meter, 4 ... brightness around LED display screen 1, 5 ... A / D converter, 6 ... brightness of LED display screen, 7 ... brightness detection Reference numeral 8 ... Comparator, 9 ... Luminance difference set value, 10 ... Comparator, 11 ... Control calculation portion, 12 ... Luminance signal amplification portion, 13 ... LED luminance signal, 14 ... Comparator, 15 ... Thermometer, 16 ... Device internal temperature set value, 17 ... A / D converter, 18 ... Comparator, 19 ... Control computing unit, 20 ... Luminance signal amplifying unit, 21 ... LED luminance signal, 22 ... LED display, 23 ... Control computing unit , 24 ... Luminance signal amplification section, 25 ... LED display, 26 ... Device internal temperature, 27 ... Control calculation section, 28 ... Luminance decrease signal, 29 ... Comparator, 30 ... Delay section, 31 ... Comparator, 32 ... Change amount Detector, 33 ... Change amount setting unit.

Claims (5)

[Claims] 1. An LED display device main body having an LED display screen, an illuminance detection unit attached to the LED display device main body for detecting the brightness around the LED display screen, and detecting the brightness of the LED display screen. Brightness detecting means, comparing means for comparing the ambient brightness detected by the illuminance detecting means and the brightness of the LED display screen detected by the brightness detecting means, and a brightness difference as a comparison result by the comparing means. On the basis of,
An LED display device, comprising: a control unit that outputs a brightness signal to adjust the brightness of the LED display screen so that the brightness difference becomes equal to a preset setting value. 2. An LED display device main body having an LED display screen, temperature detection means attached to the LED display device main body for detecting the internal temperature thereof, and the device internal temperature detected by the temperature detection means and preset. A comparison means for comparing the set value thus set, and a control means for adjusting the result of the comparison by the comparison means so as to reduce the brightness of the LED display screen when the internal temperature of the device rises above the set value. An LED display device characterized by the above. 3. An LED display device main body having an LED display screen, an illuminance detecting means attached to the LED display device main body for detecting the brightness around the LED display screen, and detected by the illuminance detecting means. An LED display device, comprising: a control unit that outputs a brightness signal so as to change the brightness of the LED display screen according to the ambient brightness. 4. The L according to claim 1 or claim 3.
In the ED display device, to reduce the brightness of the LED display screen according to the temperature detection means attached to the LED display device main body and detecting the internal temperature thereof and the device internal temperature detected by the temperature detection means. An LED display device further comprising: a control unit that outputs a brightness reduction signal to the brightness signal. 5. The LED display device according to claim 1, wherein the illuminance signal output from the illuminance detection means is delayed by a predetermined time. Comparing means for comparing the level value of the illuminance signal delayed by the delay means and the current illuminance signal, and change amount detecting means for detecting the change amount of the illuminance signal based on the value compared by the comparing means, The change amount of the illuminance signal detected by the change amount detecting means is compared with a preset setting value, and when the change amount is larger than the set value, a delay value is set, and when the change amount is larger than the set value. An LED display device characterized by being provided with change amount setting means for outputting respective current values when the values are small.