JPH0460688A - Information display device - Google Patents

Abstract

PURPOSE:To automatically detect trouble to display it in a short period of time by writing test data and detecting the change of the output current of an LED driving power source of a display device and comparing it with a prescribed current change and displaying the result. CONSTITUTION:When a CPU 21 generates test data '1' and writes it n a display device 1, the driving current flows from a power source device 5 to anode drivers 12 and cathode drivers 13 to light all bits of LEDs (light emitting diodes) 14. Since the driving current of LEDs 14 at this time is considerably increased in comparison with that for non-lighting, this current change is detected by a current detector 6 and is read into a controller as a signal, and it is discriminated whether the change is larger than a certain value or not, and normalcy is displayed on a monitor 24 when it is larger tan the certain value, but abnormality is displayed there when it is not larger. Next, data '0' is generated and is written in the display device 1, and it is discriminated whether the output is normal or not and the result is displayed in the same manner. Thus, the presence or the absence of trouble of the display device 1 is automatically detected and displayed in a short period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a large-sized information display device using light emitting diodes (LEDs) and the like.

2. Description of the Related Art Conventionally, this type of display device has a large number of dot-type display elements arranged vertically and horizontally in a matrix, and characters and figures to be displayed are displayed as a collection of dots.

Next, the above conventional example will be explained with reference to FIG.

In FIG. 4, display data corresponding to the LED 34 on the top row is serially written from the control device 30 to the shift register 31, and when all bits are aligned, the anode driver 32 and cathode driver 33-1 are activated. ,
The LED 34 corresponding to the data "1" is turned on and lights up. Next, in the same way, LED 3 one row below
Display data corresponding to 4 is written, the cathode drive 332 is activated, and a display is performed. Similarly, the cathode drivers are sequentially scanned to display the entire surface.

In this way, the above-mentioned conventional LED display device writes display data in a shift register in series, reads it out simultaneously in parallel, and drives the LED corresponding to each bit, thereby displaying the negative row. By sequentially scanning in the vertical direction as well, the entire surface can be displayed.

Problems to be Solved by the Invention However, since the conventional method described above only has the function of outputting display data, for example, even if the LED itself or the driver circuit is disconnected, it cannot be detected, and it is difficult to determine whether the LED is actually lit. The only way to confirm this was to rely on the human eye. In other words, failures are only discovered when something is visually abnormal, making automatic diagnosis impossible, delaying failure discovery, and requiring time to repair equipment, which requires large scale and high reliability. This was a big problem in the system.

The present invention solves these conventional problems, and provides an excellent display device that allows equipment to automatically detect the above-mentioned fault and display it to maintenance personnel so that the fault can be quickly repaired. The purpose is to

Means for Solving the Problems In order to achieve the above objects, the present invention provides a function for writing test data, and a function for detecting changes in the output current of the power supply for driving the LEDs of the display device and comparing them with the original changes in current. and a function to display the results.

Therefore, according to the present invention, by writing test data and determining whether the output current change of the LED drive power source is as expected, it is possible to determine whether the LEDs and drive circuit of this display device are operating normally. It is possible to determine whether the system is present or not, and if there is an abnormality, it is displayed so that maintenance personnel can recognize it and take corrective action.

Embodiment FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 1 is the display device to be tested and 2 is the control device. The control device 2 includes a control CPU 21 and a clock 2.
2, an input keyboard 23, and a monitor 24 for displaying test results. The display device 1 is supplied with driving power from a commercial AC power source via a power supply device 5. A of this power supply device 5
A current detector 6 detects changes in the C input current or the DC output current.

The control device 2 is connected to the display device 1 by a line 3 for writing test data and a line 4 for reading out changes in the power supply current.

Details of the display device 1 are shown in FIG. In this example,
If the display screen has M dots horizontally and L dots vertically, the shift register 11 generally has M bits corresponding to the number of horizontal dots. Also, in the vertical direction, there are generally N screens (M=
1.2. ...), and there are N lines 3 and 4 depending on the display system. N
The case of =3 is shown in FIG.

21 is a CPU, which corresponds to the CPU 21 in FIG. 11 is a shift register, 12 is an anode driver, 13 is a cathode driver, 14 is an LED arranged in a matrix,
51 is a gate circuit, and 52 is a gate selection circuit. Third
Details of the current detector 6 are shown in Figures (a) and (bl). In Figure (a), the DC output of the power supply device 5 is supplied to the display device 1 via a current detection resistor 61, and is proportional to the current. This generates a voltage drop V, which is taken out as an electrical signal on line 4 by amplifier 62 and output to control device 2 .

Since a voltage drop is undesirable during actual operation, the resistor 61 is short-circuited using the contact 63, and the contact 61 is connected only during testing.
You may also open it. Also, in the same figure (bl shows an example of a detection method for AC current change. In the same figure, when an AC current flows over a certain value, an electromagnetic relay 64 operates, and an amplifier 65 outputs this as an electric signal to line 4. I can do it.

Next, the operation of the above embodiment will be explained. In FIG. 1, when a test start is designated from the input keyboard 23, the CPU 21 generates test data "1" and lines 3
Write to display device 1 via. This data is sequentially transmitted through the shift register 11 in FIG. 2, and when M bits are written, the anode driver 12 is turned on.
The drive current is passed from the power supply device 5 to the anode driver 12.
The signal flows to the LED 14 via , flows to the cathode driver 13, and all bits of the LED 14 are lit. At this time, the LED drive current increases significantly compared to when the LED is not lit, so the current detector 6 can easily detect this current change. This change is read as a signal to the control device 2 via line 4, and it is determined whether the change is larger than a certain value, and the monitor 24 indicates that it is normal if it is "large" and abnormal if it is "small". indicate.

Next, data "0" is generated from the input keyboard 23 and written to the display device 1, and similarly it is determined and displayed whether the output is normal or not.

In this way, if the input data changes from "1" to "0" and the output changes accordingly, it is normal, and if either one of them is abnormal, it is determined to be abnormal, and the failure situation can be determined by looking at the monitor screen. It becomes possible to know.

Further, the test can be started automatically by the built-in clock 22, and the test can be automated.

Note that although the display during this test differs from the original display data, there is no problem in operation as it will be completed in a very short time.

As described above, according to the above embodiment, the test can be performed automatically or manually, and the presence or absence of a failure can be easily determined by viewing the display of the results.

Effects of the Invention As is clear from the above embodiments, the present invention can automatically detect and display the presence or absence of a failure in a display device in a short period of time, so that the reliability and maintainability of the display system are greatly improved. Ru.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an information display device according to an embodiment of the present invention. FIG. 2 is a detailed block diagram of the display device section of FIG. 1, and FIG. FIG. 4 is a block diagram showing an example of a conventional display device. 1...Display device, 2...Control device, 3
．． 4...Line, 5...Power supply device, 6
... Current detector, 11 ... Shift register, 12 ... Anode driver 13 ...
...Cathode driver, 14...LED115
...Voltage output, 21...CPU, 22
...Clock, 23 ...Keyboard, 24
...Monitor, 51...Gate circuit, 5
2... Gate selection circuit, 61... Current detection resistor, 62.65... Amplifier, 63...
... Contact, 64 ... Name of electromagnetic relay agent Patent attorney Shigetaka Awano et al. 18 Figure 3 (CL) figure

Claims (1)

[Claims] a display device including at least light emitting diodes arranged in a matrix and a driver for driving the light emitting diodes, and means for writing test data into the display device;
An information display device comprising means for detecting a change in output current of a power source for driving a display device, and means for comparing the current change with an input and displaying the result.