JPH04134079U - Failure detection circuit for light emitting indicators - Google Patents

Abstract

(57) [Summary] [Purpose] Detect short circuits and disconnection faults in light emitting diode indicators. [Structure] A first transistor whose emitter is connected to a power line, a second transistor whose emitter is connected to a power line via a reference voltage of 1.4V or more, and a second transistor whose emitter is connected to a ground line. 3 transistors, the second
The collector of the transistor and the base of the third transistor are connected through the resistors of the collector of the first transistor and the collector of the third transistor, and
An input signal is input to the base of the third transistor via a resistor, and an output signal is taken out from the collector side of the third transistor.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention is used for failure detection of luminescent display devices, especially for high voltage generation circuits, X-ray generation circuits, and large power generation circuits. Failure detection of light emitting indicators used in cases where incorrect display of the status of a circuit, etc. is extremely dangerous. Regarding circuits.

0002

[Conventional technology]

Conventionally, a circuit as shown in FIG. 5 has been used for these purposes. Sunawa For example, when starting the high voltage device 200 such as a high voltage generation circuit using the switch 22', In this case, the light is emitted through the resistor 21 by another switch 22 that is linked to the switch 22'. A light emitting diode display 20 as an indicator is turned on, and a device 20 such as a high voltage device A method is used to notify the user that 0 is activated. At this time, the light emitting diode If the code display 20 is malfunctioning for some reason, the user can check whether the device is running or not. Thinking that something is not there, do not approach, enter, or even touch the dangerous area. There is a possibility of an accident.

0003 Therefore, if the light emitting diode display 20 is out of order, the high voltage device 200 It is necessary to prevent it from starting. The failure mode of the light emitting diode display 20 is There are two types of failures: short circuits and disconnections, and both types of failures must be detected. A conventional example of a failure detection circuit for a light emitting diode display for this purpose is shown in FIG. In the diagram 400 is a short circuit detection circuit, 401 is a disconnection detection circuit, and 402 is an OR circuit. 40 The short circuit detection circuit 0 or the disconnection detection circuit 401 is connected to the light emitting diode display 20. When a failure is detected, a failure run (not shown) is sent to the device 200 through the OR circuit 402. This notification is displayed on the screen or by turning off the power of the device 200.

0004

[Problem that the idea aims to solve]

However, the conventional circuit has the disadvantage that the circuit is complicated. breakdown Circuits that detect As the number of parts increases, reliability tends to decrease, while cost increases and simple A circuit with a small number of parts is desired.

[0005]

[Means to solve the problem]

・Light-emitting indicator, ・The anode terminal of the light emitting display is connected to the base via the first resistor, and the emitter is a first transistor connected to the positive power supply; ・Connect the cathode terminal of the light emitting diode display to the base via a second resistor. , the emitter is connected to the positive power supply via a reference voltage source of 1.4V or higher. Ranjistor ・Connect the collector and base of the second transistor, and connect the emitter to the ground wire (negative voltage a third transistor connected to the source) and the collector of the third transistor and the collector of the first transistor are connected through a third resistor, and the third transistor is connected to the collector of the first transistor through a third resistor. A failure detection circuit for a light emitting display that takes out the output from the collector of the register.

[0006]

[Effect]

In the case of a short-circuit fault, neither the first nor the second transistor turns on, and the slave Since the third transistor is not turned on, the output terminal is in a floating state. Ru. In addition, in the case of an open circuit failure, the first transistor, second transistor, and third transistor Both transistors are turned on, and the output terminal becomes approximately at ground potential.

[0007] Therefore, devices such as high voltage generators are equipped with a load between the output terminal and ground, and the By monitoring the status, you can know the operating status of the LED indicator. . Also, if you want to distinguish the floating state, use a light emitting diode display. It is also possible to know the type of equipment failure.

[0008]

【Example】

FIG. 1 shows an embodiment of the present invention. This will be explained below according to the drawings. First, the light emitting diode display as a light emitting display has the following characteristics. ing. Note that the light-emitting display may be of any type, such as a heat-generating resistor lamp. That is, When the lamp is lit normally, the voltage between the anode and cathode is approximately constant at 1 to 2V. ing. The types of failures include short circuit failures and disconnection failures.

[0009] Therefore, when the switch 22 is closed in FIG. If 0 is normal, the voltage between terminals 1 and 3 is between 1 and 2V. In addition, if the light emitting diode 20 has a short circuit failure, the terminal 1 and terminal 3 is approximately zero volts. On the other hand, in the case of a disconnection fault, the voltage between the terminals is Almost equal to the power supply voltage.

0010 First, when the light emitting diode display 20 is normal, the first transistor 13 is However, the second transistor 14 is not turned on. Also, the third transistor 15 doesn't turn on either. Therefore, a potential approximately equal to the power supply voltage is output to the output terminal 4. Ru. Next, in the case of a short-circuit failure, both the first transistor 13 and the second transistor 14 is not turned on, and therefore, the third transistor 15 is also not turned on, so the output terminal 4 is turned on. It will be in a loading state.

[0011] In addition, in the case of a disconnection failure, the first transistor 13, the second transistor 14, Both the third transistor 15 is turned on, and the output terminal 4 is almost at ground potential. Become. Therefore, the device 200 (see FIG. 2) provides a load between the output terminal 4 and the ground. By monitoring the potential, it is possible to know the operating state of the light emitting diode indicator 20. I can do it.

0012 Also, if you want to distinguish the floating state, use a light emitting diode display. It is also possible to know the failure type of the device 20. FIG. 2 shows a case where the light emitting diode detection circuit according to the present invention is used with the device 200. An example is shown below. When the start switch 201 is turned on, the device 200 starts operating. At the same time, the light emitting diode display 20 is turned on through the display line 202 and the resistor 21. to notify that the device has entered the operating state.

[0013] If there is a failure in the light emitting diode display, the failure detection circuit 100 will detect the failure. The failure of the light emitting diode indicator 20 is notified to the device 200 through the detection line 203. Moreover, FIG. 3 shows another embodiment. Light emitting diode display failure detection circuit 100 The output of output terminal 4 is stomach. When the switch 22 is off, or when the switch 22 is on and the display 20 is short-circuited... High impedance state B. When the switch 22 is on and the display 20 has a disconnection failure...Low potential C. When the switch 22 is on and the display 20 is normal...high potential Therefore, the device 200 detects that the output signal 205 of the detection circuit 100 has a high potential. Make it start only when

[0014] This embodiment has the following advantages over the embodiment of FIG. stomach. There is only one signal line connecting the device 200 and the failure detection circuit 100, and the 200 can be directly replaced. B. In the embodiment shown in FIG. 2, in the worst case, the sequence of activation-lighting-fault detection-stopping-starting is performed. Although there is a risk of repeating starting and stopping in a cycle, there is no such risk in the example shown in FIG. C. Switch (or drive circuit) and device that lights up the light emitting diode display The reliability is high because the switch that activates them is the same.

[0015] FIG. 4 shows another embodiment. In other words, the light is emitted inside the illuminated switch 300. It incorporates a failure detection circuit 100 for a photodiode display. By doing this, in terms of space, the start switch of the device 200 can be directly connected. It can be replaced.

[0016]

[Effect of the idea]

As we have seen above, the present invention is extremely simple and reliable, and LED display has the advantage of being able to directly replace the switch. A fault detection circuit can be obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a third embodiment of the present invention.

FIG. 4 is a perspective view showing a fourth embodiment of the present invention.

FIG. 5 is a block diagram of the prior art.

[Explanation of symbols]

1 Power terminal 2 Ground terminal 3 Detection terminal 4 Output terminal 10, 11, 12 resistance 13, 14, 15 transistor 16 Reference voltage source 20 Light emitting diode display 21 Resistance 22 Start switch 100 Light emitting diode display failure detection circuit 200 Controlled device 300 illuminated switch

Claims (1)

[Scope of utility model registration request] 1. A light emitting display; and a first transistor connected to the anode terminal of the light emitting diode display through a first resistor, the emitter of which is connected to the positive power source; and the cathode terminal of the light emitting diode display. A second transistor is connected to the base through a second resistor, and the emitter is connected to a positive power supply through a reference voltage source of 1.4V or higher.The collector and base of the second transistor are connected to each other, and the emitter is Consists of a third transistor connected to the ground wire (negative power supply),
A failure detection circuit for a light emitting display, in which a collector of a third transistor and a collector of a first transistor are connected through a third resistor, and an output is taken out from the collector of the third transistor.