JP2003015580A - Image display apparatus and method for detecting failure of light emitting display element used therein - Google Patents

Abstract

(57) [Problem] In a conventional video display device, a circuit for checking a non-lighting failure of a light emitting display element temporarily stops video display of the video display device and then applies a voltage to the light emitting display element. Then, the value of the current flowing at that time was monitored. However, since many non-lighting failures occur during image display, there is a problem in that the conventional method delays finding the failure. SOLUTION: A voltage is applied to a light emitting display element 3 to be inspected during a vertical blanking period 101a of one field 101 during image display, and a current flowing at this time is monitored. Also, by applying a voltage 111a to all the light emitting display elements other than the inspection target during the same vertical blanking period 101a,
The screen is made to emit light evenly, and light emission for inspection 1
Make 10a inconspicuous.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device in which light emitting display elements are arranged as pixels, and a method for detecting a defective element of a light emitting display element used in the same.

[0002]

2. Description of the Related Art There is an image display device of a type in which light emitting elements are arranged in a plane to form an image display screen. For example, there are so-called plasma displays in which discharge elements are arranged and LED displays in which light emitting diodes are arranged. In the present invention, such displays are collectively referred to as a video display device. The light-emitting element used in such an image display device is one that is extremely hard to fail, but since the number of uses is huge, sometimes it sometimes fails and cannot emit light. In this case, the part that does not emit light is visually recognized as a black dot and the quality of the image is deteriorated. Therefore, it is necessary to detect it early and take measures such as replacement.

Therefore, a device for finding a defective light emitting element of an image display device has been conventionally proposed. Figure 11
Is disclosed in JP-A-10-20831,
FIG. 3 is a block diagram of a failure detection circuit for the purpose of inexpensively constructing a detection circuit for a non-lighted lamp of an image display device configured using a DC discharge lamp. In the figure, reference numerals 30 and 31 denote 1-dot light emitting function units, which include DC discharge lamps 21 and 22, respectively. Since the configurations of the light emitting functional units are the same, the light emitting functional unit 30 will be described below. The discharge lamp 21 is a hot cathode type direct current discharge lamp, and the power supply 38 is the power supply for those filaments.

The power supply 37 is a power supply for the lighting current of the discharge lamp 21, and the resistor 24 and the transistor 33 together form a constant current drive circuit for the discharge lamp 21. A transistor 28 corresponds to the discharge lamp 21 and controls the lighting state.

The power supply 39 and the resistor 27 are connected to the transistor 33.
Controls the base potential in the “ON” state.
The magnitude of the voltage of the power source 39 is set to about 4 to 5 times the voltage between the base and the emitter of the transistor 33. The magnitude of the resistance value of the resistor 24 is set by the magnitude of the current to be passed through the discharge lamp 21 and the voltage of the power source 39.

The transistor 33 has a DC amplification factor of 100 or more, and the resistance value of the resistor 27 is about 4 to 5 times that of the resistor 24. The comparator 43 is provided to sense the base potential of the transistor 33, and senses the base potential with the diode 25. In addition, the diode 25 is configured to be able to sense the lowest potential state.

The output of the comparator 43 is input to the non-lighting check sequencer 40. The non-lighting check sequencer 40 turns “ON” to the display control signal generator 41.
The lamp to be turned on is instructed, and the gate voltage of the transistor 28 is controlled according to the instruction. The non-lighting check sequencer 40 is configured to be able to write the non-lighting information to the non-lighting information memory 42.

Next, the operation of the one shown in FIG. 11 will be described. A constant current flows through the discharge lamp 21 by the constant current drive circuit composed of the power supply 37, the resistor 24 and the transistor 33. The state of the transistor 33 is controlled by the transistor 28, and the transistor 28 is “ON”.
At this time, the discharge lamp 21 is turned off without any current flowing.
The discharge lamp 21 when the transistor 28 is "OFF"
Is lit by current flowing. The state of the transistor 28 is
It is controlled by the voltage output from the display control signal generator 41.

The base potential of the transistor 33 is the power supply 3
As compared with 9, the potential becomes higher by the voltage drop generated in the resistor 27. When a current flows in the discharge lamp 21, a voltage drop occurs in the resistor 24 due to the emitter current, and the resistor 27
A voltage drop occurs due to the base current. When the transistor 33 has a DC amplification factor of 100 or more and the resistance value of the resistor 27 is about 4 to 5 times that of the resistor 24, when a current flows through the discharge lamp 21, the voltage drop of the resistor 24 is the voltage of the resistor 27. It will be about 20 times the size of the descent.

The magnitude of the voltage of the power supply 39 is set to the transistor 3
If the voltage is set to about 4 to 5 times the voltage between the three base emitters, when a current flows through the discharge lamp 21,
The voltage across resistor 24 is controlled to be approximately constant, resulting in a substantially constant current through the lamp. When the transistor 28 is “ON”, the base potential of the transistor 33 has the same value as the plus side of the power source 19, the voltage drop of the resistor 27 becomes the same as the voltage of the power source 19, and the voltage drop of the resistor 24. Is zero.

When no current flows due to some failure of the discharge lamp 21, the collector current does not flow in the transistor 33, so that the emitter current = base current, and the voltage drop across the resistor 24 is the discharge lamp 21. Value is sufficiently smaller than that when the current of
The base potential of the power supply 39 is lower than that of the power supply 39 by the base-emitter voltage of the transistor 33.

The input terminal 35 of the comparator 43 is connected to the base terminal of the transistor 33 by the diode 25. As a result, the transistor 3 is connected to the input terminal 35.
A potential larger than the lower one of the three base potentials by the voltage drop of the diode appears. A reference potential generating power supply 34 is connected to the input terminal 36, and the power supply 34 responds to changes in the base potential of the transistor 33 by the discharge lamp 2.
The potential is set to be higher than the potential of the input terminal 35 when the lamp current of 1 flows, and lower than the potential of the input terminal 35 when the lamp current of the discharge lamp 21 does not flow.

The comparator 43 outputs an H level when the potential of the input terminal 35 is larger than the potential of the input terminal 36.
When the potential of the input terminal 35 is smaller than the potential of the input terminal 36, the L level is output. As a result, when a current flows through any of the discharge lamps, a potential smaller than that of the input terminal 36 appears at the input terminal 35, and the output of the comparator 43 becomes L level.

A transistor 28 of the light emitting functional unit 30;
By checking the output of the comparator when only one of the same transistors of the light emitting function unit 31 is in the “OFF” state and a current is to flow through only one of the discharge lamps 21, 22, the discharge lamp 21, It is possible to know that 22 is not lit.

In FIG. 11, the non-lighting check sequencer 40 tells the display control signal generator 41 that the lamp 2
A command to turn on only one of 1 and 22 is given. According to the output signal of the display control signal generator 41, the discharge lamps 21 and 22
Is determined, the level indicating the current state is output from the comparator 43, and the non-lighting check sequencer 40
Can know whether the currently lit lamp is on or off, and stores the information in the non-lighting information memory 42.

Thus, the display control signal generator 41 turns on only one of the discharge lamps arranged in a large number and sequentially turns on the turn-on for all the discharge lamps. Corresponding to these lighting, the comparator 13 changes the potential of the input terminal 15 to the input terminal 16 each time.
Is compared with the reference potential and the comparison result is transferred to the non-lighting check sequencer 40.

[0017]

In the conventional image display device, when it is desired to inspect the light emitting display elements or all the light emitting display elements to be inspected, they are inspected according to the inspection program inputted in advance. It is necessary to turn on the lamps in order. The indicator lights that turn on in sequence are visually recognized as the movement of the light spot on the screen, so it is necessary to temporarily stop the image display and inspect it.In practice, the inspection is performed during the image display operation. Can not. Further, there is a problem that a failure of the light emitting display element that occurs during image display cannot be detected.

The present invention solves the above problems,
The light spot during inspection is not visually recognized, and therefore, the failure detection method of the light emitting display element capable of executing the failure detection of the light emitting display element regardless of whether the image is being displayed, and the image display using this failure detection method The purpose is to provide a device.

[0019]

An image display apparatus according to the present invention displays an image by displaying an image display screen formed by arranging a plurality of light emitting display elements, and sending a 1-field image signal to the plurality of light emitting display elements. A display control logic for controlling the video display screen by providing a video display period for allowing the video display period and a vertical retrace line period provided continuously with the video display period for not displaying the video image; A voltage is applied to at least one of the light emitting display elements to emit light,
At this time, when the value of the current flowing through the light emitting display element is equal to or lower than a predetermined level, it is determined that the one light emitting element is abnormal, and position data of the one light emitting element on the image display screen is displayed. And a non-lighting element detection circuit for outputting an alarm signal including

Further, the non-lighting element detection circuit sequentially selects and switches the light emitting display elements to which the voltage is applied for each field.

The non-lighting element detection circuit randomly selects and switches the light emitting display elements to which the voltage is applied for each field.

In addition, the non-lighting element detection circuit sets the timing at which the voltage is applied to all the light emitting display elements other than the light emitting display element to which the voltage is applied during the vertical blanking period of 1. Outputs an inversion lighting command for applying a voltage at another timing.

The non-lighting element detection circuit is provided with an adjustment circuit for adjusting the length of time for which the voltage is applied according to the type of light emitting display element used.

Further, a voltage is applied to a plurality of the light emitting display elements for inspection during one blanking period.

A method of detecting a failure of a light emitting display element according to the present invention includes:
An element selection procedure for selecting an element for failure detection and obtaining its position data, a voltage application procedure for applying a voltage to the target light emitting display element during the vertical blanking period of 1, a target according to the applied voltage The determination procedure for determining whether or not the magnitude of the current flowing through the light emitting display element is equal to or less than a predetermined level, and when the determination procedure determines that the current is less than or equal to An alarm procedure for outputting, a position data output procedure for outputting position data of the light emitting display element that has output the alarm, a current is passed through the light emitting display elements other than the target light emitting display element during the vertical blanking period, and A homogenization procedure to homogenize the brightness,
It includes an iterative procedure in which all the above procedures are repeated for each field.

The voltage applying means applies a voltage to the plurality of light emitting display elements during one blanking period.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. FIG. 1 shows the configuration of a video display device according to the first embodiment of the present invention. Also,
FIG. 2 is a time chart explaining the operation of the light emitting display device having the configuration of FIG. 1, FIG. 3 is an operation explanation on the video display screen,
As shown in FIG. In FIG. 1, reference numeral 1 is a light emitting display element power supply (hereinafter referred to as a power supply). Reference numeral 2 is a non-lighting detection circuit (hereinafter referred to as non-lighting element detection circuit) of the light emitting display element inserted between the power source 1 and the light emitting display element 3. Although only one light emitting display element 3 is shown here, a large number of elements are arranged in a plane to form an image display screen (not shown). Image data 4 is externally input to the video display device. 5 is an R for temporarily storing the image data 4
AM. 6 is information about the failure of lighting of the light emitting display element 3,
A RAM for temporarily storing work data of the microcomputer 10 and a display control logic 7 for reading image data from the RAM 5 to generate a driver driving signal for the light emitting display element 3 and the like. 8 is a driver circuit for driving the light emitting display element 3,
Reference numeral 9 is an external command for instructing the image display device to execute the inspection of the display element and the like, and 10 is a microcomputer for integrally controlling these. Reference numeral 11 is a control block including the control logic 7 and the like, and 12 is a non-volatile ROM for storing programs and initial setting values of the microcomputer. Reference numeral 50 denotes a video display device, which includes the video data 4 of FIG. 1 and other parts except the external command 9.

Next, the operation will be described. Video data 4
The operation for displaying is the same as the known conventional display operation, and therefore will be briefly described. The video data 4 input from the outside is once taken in by the display control block 7 and stored in the video data RAM 5. The stored video data is read into the display control logic 7 again for each one field, and subjected to necessary arithmetic processing such as contrast adjustment processing, and then output to the driver circuit 8. FIG. 2 shows the timing of the video signal thus output. Between the video signal 101 of the nth field and the video signal 102 of the next (n + 1) th field, the scanning position of the light spot is changed from the end (generally the lower end) of the screen to the other end (the upper end). Since it takes time to return it,
Period in which no video signal is output (vertical blanking period) 101
a, 102a ... Are provided.

The display control block 7 of FIG. 1 performs non-lighting failure detection for an arbitrary light emitting display element (for example, one) during the vertical blanking period of FIG. 2, for example, 101a. This non-lighting failure detection is a signal obtained by inverting the lighting / non-lighting command of the non-lighting failure detection signal for all the light emitting display elements other than the above-mentioned target lighting signal for inspection for the one element. And are output continuously. Then, during the next vertical blanking period, a similar signal for another one is output to, for example, 102a, and this is sequentially repeated during each vertical blanking period. If, for example, there are A video display elements in total, all display elements are inspected once the A fields have been displayed. Since a predetermined current flows through the light emitting display element 3 which is turned on by the inspection lighting signal, an abnormality (non-lighting) can be detected by monitoring the magnitude of this current using, for example, the microcomputer 10.

The timing of the non-lighting failure detection signal and its inverted signal will be described with reference to FIG. FIG. 3A shows a video signal 101 of one field and a non-lighting failure detection signal 110.
a and its inverted signal 111a are shown, and FIG. 3B is an enlarged view thereof. In the figure, 110 is a vertical blanking period 10
The first half of 1a is called a lighting command period. 111 is the latter half and is also called the reverse lighting instruction period. The lighting instruction period 110 and the reverse lighting instruction period 111 are divided into substantially the same time length. Then, during the lighting command period 110 in the vertical blanking period 101a, the lighting command 110a is output to one light emitting display element for detecting a failure, and the reverse lighting in the vertical blanking period 101a is also performed. During the command period 111, the lighting command 111a is output to the light emitting display element for which failure detection is not performed.

Here, in both the lighting instruction period 110 and the reverse lighting instruction period 111, the time position in the entire period corresponds to each of the light emitting display elements constituting the screen. That is, the inside of the light emitting display element driver 8 is composed of a shift register and a latch, and a drive signal for driving the same is calculated in the display control logic 7 and then input as a serial signal. Depending on the position, which position of the data corresponds to which position of the light emitting display element can be determined in advance. FIG. 4 shows an example of the positional relationship between the lighting instruction period 110 and the corresponding light emitting element on the screen. The same applies to the reverse lighting instruction period 111.

In FIG. 4, 51 is a screen and 52 is a horizontal scanning line. For convenience of explanation, l, k, m, and n indicate the positions provided above the lighting command period 110, and L, K, m, and n.
M and N indicate the positions of the light emitting elements on the screen corresponding to the positions 1, k, m and n. That is, the lighting command period 110
Alternatively, the positions from the left end to the right end of the reverse lighting instruction period 111 correspond in order from the upper left of the screen 51 to the lower right along the horizontal / vertical scanning lines of the screen. Since the time 110a for turning on the light emitting display element 3 for detecting a failure is extremely short,
Although the light emission due to this is only slightly visible as a light spot, when only the lighting instruction period 110 is provided, the light spot moves regularly in each field, and thus is visually recognized as a line. However, in the present invention, the reverse lighting command period 111 is provided immediately after the lighting command period 110 for failure detection to turn on all the indicator lamps that are not the target of failure detection. Therefore, as shown in FIG. Shines evenly and is not visible as a light spot or line. In FIG. 5, 118 is a lighting instruction period 1
10 is a screen at a certain moment, 119 is a screen of the reverse lighting command period 111 immediately after the screen, and 120 is a screen state which is visible as a result. In the above description, it is described that there is one light emitting element that detects a failure in one field, but a plurality of light emitting elements may be detected simultaneously.

The above operation will be described as a failure detection method for the light emitting display element 3 and its procedure will be described with reference to the flowchart of FIG. In FIG. 6, step S1 is an element selection procedure for selecting an element to be a failure detection target. The position data of the target element is obtained by this selection. Step S2 is a voltage application procedure for applying a voltage (flowing a current from the constant current circuit) to the target light emitting display element during the vertical blanking period 101a. Step S3 is a determination procedure for determining whether or not the magnitude of the current flowing through the target element is below a predetermined level. Step S4 is an alarm procedure for outputting an alarm as an abnormality of this element when the following is determined in the determination procedure of step S3. Step S5 is a position data output procedure for outputting the position data of the light emitting display element that has output the alarm. Step S6 is a procedure for changing the target element position for the next failure detection performed in the next field. Step S7 is a homogenization procedure for homogenizing the brightness of the screen by causing a current to flow through the elements that did not flow current for fault detection during the same vertical blanking period following step S2. The above steps are repeated for each field (iteration procedure).

Embodiment 2. In the description of the first embodiment, it has been described that the current flowing through the light emitting display element 3 is monitored by using, for example, a microcomputer, but it may be configured by an analog circuit as described below. FIG. 7 shows an example of the element non-lighting out circuit 2 of the light emitting display element of FIG. 1 according to the first embodiment. When the light emitting display element 3 emits light in response to the input of the lighting command 110a in FIG. 3, current consumption flows through the diode 16 connected in series to the light emitting display element 3, and current consumption does not flow without light emission. At the timing of 110a, the resistance value is set in advance so that the positive terminal of the comparator input has a voltage higher than the voltage of the negative terminal of the comparator input when no current flows through the diode 16 for non-lighting failure detection. The output becomes H.

When the light emitting display element 3 is normal, a current flows through the failure detection diode 16, the cathode potential of the failure detection diode drops, and the comparator input (one) is compared to the reference voltage and the one input (+) is supplied. When it becomes low, the comparator output becomes L. In this way, the non-lighting element detection circuit 2 can monitor the display element current flowing in the light emitting display element to determine whether or not light is emitted, that is, whether or not there is a non-lighting failure. Fault detection diode 1 in FIG.
The insertion position of 6 is not limited to the position shown in the drawing, and may be any position as long as it is connected to the light emitting display element 3 in series. The output of the non-lighting element detection circuit 2 of FIG. 7 determines the position of the defective element from that timing, outputs the result to the display control logic 7, and outputs it to the memory 6 for external reference. to enable. In the above-mentioned failure detection, the position of the element to be detected is sequentially moved, and one point is inspected for each field as shown in FIG. The position of the indicator lamp to be inspected changes as the field progresses.

In the circuit of FIG. 7, one comparator 15
Since it corresponds to all the indicator lights, if, for example, two of them are inspected during one vertical blanking period, it becomes impossible to separately output two faults / normalities. However, since the non-lighting failure can be found by looking closely at the display screen, for example, it is sufficient for practical use if the information that one of the two adjacent ones is the failure is output, and the failure of the detection is detected. The efficiency is doubled so that the same circuit can be used when inspecting more than one during one vertical blanking period.

Embodiment 3. In the failure detection methods of the first and second embodiments, since current is passed through the light emitting display element 3 for detection, the element is turned on and the screen emits useless light, so that the image quality is deteriorated accordingly. Therefore, a method of making this light emission as low as possible will be described. FIG. 9 shows a shortened lighting command period 110 and a reverse lighting command period 111 for detecting a non-lighting failure, both of which are shortened to, for example, 1/2 or 1/3 of the baseline period 101a. There is. In this case, the comparator 15 for current detection described in the second embodiment needs to have a higher operation speed, but an example using a light emitting diode as the light emitting display element 3 will be described. Then, even if the lighting instruction period 110 is set to 2 μs, the non-lighting failure can be sufficiently detected. At this time, the non-lighting failure detection light emission rate in one field of 16.6 ms was as small as 0.01%, which was almost invisible. Since the minimum time during which a failure can be detected varies depending on the type of light emitting element, it is desirable that the non-lighting element detection circuit 2 be adjustable. The lighting command period 110
The position of the reverse lighting command period 111 in the vertical blanking period 101a is not limited to the position shown in the figure, and may be before or after the reverse lighting command period 111.
The lighting instruction period 110 may come later.

Fourth Embodiment In FIG. 8 of the second embodiment, it has been described that the position of the target element to be inspected is regularly moved field by field, but if it is regularly moved, it becomes noticeable even though it is averaged by the reverse lighting. Therefore, the position of the display element of the failure detection target may be randomly determined for each field, for example, using a random number table. The irregularity here means that the positions of the display elements that are sequentially selected have no regularity.

Embodiment 5. In the description of the first to fourth embodiments, the failure of one light emitting display element is detected for each field, but as described in the third embodiment,
If the detection time is shortened, it is possible to detect a failure of a plurality of light emitting elements in one field. FIG. 10 shows a case where failure detection of three light emitting display elements is performed in one field. In the figure, 130, 131, 13
Reference numeral 2 is the first, second, and third non-lighting failure detection signals, and 133 is an inverted lighting signal. First non-lighting failure detection signal 13 of the second, third
The positions of 0, 131, and 132 may be regular or irregular, but it is preferable not to detect the same point at the same time.

[0040]

As described above, since the image display device of the present invention detects the failure of the light emitting display element during the vertical blanking period, it is possible to detect the failure while continuing the image display.

Further, since the failure detection element is switched for each field of the screen, the failure detection of all the light emitting display elements can be carried out while the image display is continued.

Further, when switching the elements for detecting the failure for each field of the screen, the switching is performed in a chaotic manner, so that the elements emitting light for the failure detection are not conspicuous and the image quality is not deteriorated.

Further, since the light emitting element for detecting the failure and the light emitting element which is not the object of the failure detection are both turned on with a slight timing difference, the screen does not emit light uniformly and the quality of the image display is not deteriorated.

Further, since the time length of light emission for detecting a failure can be adjusted according to the type of the light emitting display element, it can be applied to various display devices.

Further, in this image display device, since a plurality of light emitting display elements can be inspected during one blanking period, the inspection efficiency is improved.

Since the method of detecting a failure of the light emitting display element of the present invention includes a procedure of applying a voltage to the target light emitting display element during the vertical blanking period and detecting an abnormality of the element based on the level of the current. The failure can be detected while continuing the image display.

Further, since the method of detecting a failure of the light emitting display element is a method of inspecting a plurality of elements during one blanking period, the inspection efficiency is good.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a video display device according to a first embodiment of the present invention.

FIG. 2 is a timing explanatory diagram of a video signal for explaining the operation of FIG.

3 is a detailed explanatory diagram of FIG. 2. FIG.

FIG. 4 is an operation explanatory diagram of FIG. 2;

5 is an operation explanatory diagram of FIG. 2. FIG.

FIG. 6 is a flowchart illustrating the operation of the first embodiment.

FIG. 7 is a current comparison circuit for failure determination according to the second embodiment.

FIG. 8 is an explanatory diagram of timing for executing failure detection according to the third embodiment.

FIG. 9 is an explanatory diagram of timing according to the fourth embodiment.

FIG. 10 is an explanatory diagram of timing according to the fifth embodiment.

FIG. 11 is a configuration diagram of a conventional image display device.

[Explanation of Codes] 1 power supply for light emitting display element, 2 non-lighting element detection circuit, 3 light emitting display element, 7 display control logic, 8
Driver circuit, 10 microcomputer, 11 control block, 101 nth field video signal, 101
a Vertical retrace line period, 110 Lighting instruction period, 111
Reverse lighting instruction period.

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Claims (8)

[Claims] 1. A video display screen configured by arranging a plurality of light emitting display elements, a video display period in which a video signal of one field is sent to the plurality of light emitting display elements to display a video, and the video display period is continuous. A display control logic for controlling the image display screen by providing a vertical blanking period during which the image is not displayed, and applying a voltage to at least one of the plurality of light emitting display elements during the vertical blanking period. When the value of the current flowing in the light emitting display element is below a predetermined level, it is determined that the one light emitting element is abnormal, and the image display screen of the one light emitting element is determined. An image display device comprising a non-lighting element detection circuit for outputting an alarm signal including the above position data. 2. The video display device according to claim 1, wherein the non-lighting element detection circuit sequentially selects and switches the light emitting display elements to which the voltage is applied for each field. 3. The video display device according to claim 2, wherein the non-lighting element detection circuit randomly selects and switches the light emitting display elements to which the voltage is applied for each field. 4. The timing of applying the voltage to all the light emitting display elements other than the light emitting display element to which the voltage is applied during the vertical blanking period of 1, the non-lighting element detection circuit. 4. The video display device according to claim 1, wherein a reverse lighting command for uniformizing apparent screen brightness is output by applying a voltage at a timing different from the above. 5. The non-lighting element detection circuit includes an adjustment circuit that adjusts the length of time for which the voltage is applied according to the type of light emitting display element used. 5. The video display device according to any one of items 4 to 4. 6. The image display device according to claim 1, wherein a voltage is applied to the plurality of light emitting display elements for inspection during one blanking period. 7. A device selection procedure for selecting a device for failure detection from among the light emitting display devices constituting an image display screen and obtaining position data thereof, the target during the vertical blanking period of 1. A voltage application procedure for applying a voltage to the light emitting display element, a determination procedure for determining whether or not the magnitude of the current flowing through the light emitting display element targeted by the applied voltage is less than or equal to a predetermined level, When it is determined that the following, an alarm procedure for outputting an alarm as this light emitting display element is abnormal, a position data output procedure for outputting the position data of the light emitting display element that issued the alarm, during the vertical blanking period A uniforming procedure for applying a current to a light emitting display element other than the target light emitting display element to make the brightness of the screen uniform, and a repetitive procedure for repeating all the steps for each field. A method of detecting a failure of a light emitting display element, which is characterized by the above. 8. The method for detecting a failure of a light emitting display element according to claim 7, wherein a voltage is applied to the plurality of light emitting display elements during one blanking period by the voltage applying means.