JPH04115024U - Failure detection device - Google Patents

Abstract

(57) [Summary] [Purpose] The object is to realize a failure detection device that can automatically detect failures in drive signals for bar indicators without visual inspection. [Structure] The base of the LED driver 2 is connected to each of the output terminals b to f of the LED driver 2, the output terminal a is connected to the emitter of the first NPN transistor _Q1 , and the collectors thereof are all connected. NPN transistors _Q1 to _Q5 , one less than the number of output terminals, and each NP
A detection unit 6 connected to the connection point A of the collectors of the N transistors _Q1 to _Q5 , and a resistor R connected to the connection point A to detect the collector current of the transistor and input it to the detection unit 6. configured.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a failure detection device for detecting failure of a bar display.

0002

[Conventional technology]

For example, there is a bar display device in which an automobile's speedometer or tachometer is made vertical and displayed using LEDs. An example of such a bar display is shown in FIG. In the figure, reference numeral 1 denotes a bar display, which is composed of an LED driver 2 and an LED array 3 having six LED elements D ₁ to _{D 6} . Reference numeral 4 denotes a display surface on which the speed and number of revolutions can be determined by blinking the LED array 3. As is clear from the figure, when the output from the terminal of the LED driver 2 is LOW, the LED element is turned off, and when it is HIGH, the LED element is turned on. In this example, the outputs of terminals 1 to 3 are HIGH and the LED elements D ₁ to D ₃ are lit. The output of this LED driver 2 is HIGH and LOW consecutively, and LOW is not mixed in HIGH, and HIGH is not mixed in LOW. Therefore, during normal operation, HIGH never appears above LOW.

0003

[Problem that the idea aims to solve]

By the way, it is possible to prevent a failure due to a disorder in the order of voltage output that occurs in this LED driver 2. To detect, change the output from 0 to FULL and visually check the display area. , or you have no choice but to check the level of each output point with an oscilloscope, etc. As the number of LED elements increases, it becomes difficult to detect which part is malfunctioning.

0004 This invention was made in view of the above points, and its purpose is to , a bar display failure detection device that can automatically detect a failure in the drive signal of the bar display 1. The aim is to realize this goal.

[0005]

[Means to solve the problem] The present invention solves the above problems by attaching an LED array to each output terminal of the LED driver. Malfunction of the bar display that connects the cathode side of the LED element and lights up sequentially from the bottom. In a failure detection device that detects The drive signal output terminal is the emitter, and the second drive signal output terminal one level above the bottom level is connected to the emitter. a first NPN transistor connected to the base and an emitter connected to the first NPN transistor; connected to the base of the transistor, the base being connected to the third drive signal of the LED driver; a second NPN transistor connected to the output terminal; Another NPN connected to the other drive signal output terminal of the LED driver in the same way as the transistors, and each of the above transistors is one less than the number of drive output terminals of the LED driver. A detection section to which the collector of the NPN transistor is connected and input, and each of the collectors A resistor for supplying power to the connection point of the LED driver and detecting an abnormality in the output of the LED driver. It is characterized by comprising the following.

[0006]

[Effect]

When the drive signal output of the LED driver is reversed, the base of the NPN transistor The potential becomes higher than the emitter potential, the NPN transistor becomes conductive, and the collector voltage increases. Current flows, the potential of the collector decreases due to the resistance, and the detection unit detects a failure. Ru.

[0007]

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a failure detection device according to an embodiment of the present invention used in a bar display. In the figure, parts equivalent to those in FIG. 4 are given the same reference numerals. In the figure, 5 is a failure detection device of this embodiment. The failure detection device 5 has the following configuration. The base of the NPN transistor (hereinafter simply referred to as transistor) _Q1 is connected to the b terminal of the LED driver 2, and the emitter is connected to the a terminal. The base of the transistor Q ₂ is connected to the c terminal of the LED driver 2, and the emitter is connected to the base of the transistor Q ₁ . Similarly, the bases of transistors Q ₃ , Q ₄ , Q ₅ are connected to the d, e, f terminals of the LED driver 2, the emitters are connected to the bases of transistors Q ₂ , Q ₃ , Q ₄ , and each transistor Q ₁ The collectors of ~ _Q5 are all connected and connected to the power supply via a resistor R. 6 is a detection unit connected to the connection point A between the resistor R and the collector of each of the transistors Q ₁ to Q ₅ .

Next, the operation of the embodiment configured as described above will be explained. The relationship between the output of the LED driver 2 of the bar display 1 and the display pattern of the LED array 3 is limited to six as shown in FIG. 2. When the display shown in Fig. 2 is displayed, the base voltage of transistors Q ₁ to Q ₅ is equal to or lower than the emitter voltage, so all transistors Q ₁ to Q ₅ are turned off, and the voltage at point A remains the same as the power supply voltage. The signal HIGH is detected by the detection unit 6.

Next, the operation when an abnormality occurs in the output of the LED driver 2 will be described. FIG. 3 is a diagram when an abnormality occurs. In the figure, the same symbols as in FIG. 1 are used. This figure shows a case where the d terminal of the LED driver 2 is H and the c terminal is L, and the output voltage is reversed. In the transistor _Q3 , the base becomes HIGH and the emitter becomes LOW, so that I _B flows, and hence the collector current I _CE flows. The voltage drops by the resistor R, the level at point A becomes LOW, and the detection section 6 detects that an abnormality has occurred. Therefore, when checking the bar display 1, when the output of the LED driver 2 is changed from 0 to FULL, if the level at point A becomes LOW even once, the output of the LED driver 2 is abnormal.

[0011] As explained above, according to this embodiment, the failure detection circuit of the bar display can be implemented using a simple circuit. I was able to realize the road.

0012

[Effect of the idea]

As explained in detail above, according to the present invention, the bar is automatically activated without visual inspection. It is now possible to detect failures in the display drive signal, which has a great practical effect.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which a failure detection circuit according to an embodiment of the present invention is connected to a bar display.

FIG. 2 is an explanatory diagram of a normal operating state of a bar display.

FIG. 3 is an explanatory diagram of the operation of this embodiment when the bar display is in an abnormal state.

FIG. 4 is a block diagram of a bar display.

[Explanation of symbols]

1 Bar indicator 2 LED driver 3 LED array 5 Failure detector 6 Detection section D ₁ , D ₂ , D ₃ , D ₄ , D ₅ , D ₆ LED element Q ₁ , Q ₂ , Q ₃ , Q ₄ , Q ₅ NPN transistor

Claims (1)

[Scope of utility model registration request] [Claim 1] Each output terminal (a
~f) are the LED elements (D) of the LED array (3).₁~
D₆) is connected and lights up in order from the bottom.
In the failure detection device that detects failure of the bar indicator (1)
The first terminal, which is the lowest terminal of the LED driver (2),
Drive signal output terminal (a) as emitter, one stage from the bottom
The upper second drive signal output terminal (b) is connected to the base.
The first NPN transistor (Q₁) and the emitter is
The first NPN transistor (Q₁) connected to the base of
and the base is connected to the third drive signal of the LED driver (2).
A second NPN transistor connected to the signal output terminal (c)
Ta (Q₂) and the second NPN transistor (Q₂)and
Similarly, the other drive signal output terminal of the LED driver (2)
Other NPN transistors (Q
₃~Q _Five) and a drive output terminal of the LED driver (2).
Each NPN transistor (Q₁
~Q_Five) to which the collector is connected and input.
(6) and the connection point of each collector, and
Resistor for detecting an abnormality in the output of the ED driver (2)
(R) A failure detection device characterized by comprising: