JPS6180794A - Lamp disconnection detecting circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is directed to a lamp burnout that can quickly and automatically detect lamp burnout in a display device, etc. that uses a large number of lamps as display elements, without having to turn on the lamps. Regarding a detection circuit.

In the above-mentioned display devices, it is desirable that a burnout of a lamp can be detected with low power consumption and quickly and without much effort.

[Conventional technology]

Conventionally, in the case of a lamp test to detect burnout of lamps in display devices, etc., a person operates a switch to forcibly turn on all the lamps at once, and then searches for a lamp that is not lit to detect a burnout. .

[Problem that the invention seeks to solve]

However, in the above lamp test, a burnt out lamp cannot be detected until the lamp test is performed, so the detection is delayed.
In addition, since all the lamps are forcibly turned on at the same time, a large amount of power is consumed for each lamp test, and the test is time-consuming because it is performed by a skilled person.

[Means for solving problems]

The above problems are solved by a pulse generation circuit that sends out pulses at predetermined time intervals, a circuit that uses the pulses to disconnect the lamp from the drive circuit, a detection circuit that detects the presence or absence of conduction of the lamp, and a detection circuit that detects the presence or absence of conduction of the lamp. The problem is solved by the lamp burnout detection circuit of the present invention, which includes a determination circuit that determines whether the lamp is burnout by detecting when a pulse is output from the pulse generation circuit.

[Effect]

According to the present invention, the lamp is disconnected from the drive circuit during the pulse width of the pulse sent out at each predetermined time interval, and the presence or absence of conduction of the lamp is detected during the pulse width, thereby automatically turning the lamp off. Since it is determined whether the lamp is burnt out or not, it is possible to detect a burnt out lamp every time a pulse is sent, and it is also possible to detect a burnt out lamp without turning on the lamp.It is easy to use, has low power consumption, and can be detected quickly when a slump burns out. .

〔Example〕

FIG. 1 is a circuit diagram of a lamp burnout detection circuit according to an embodiment of the present invention when there is only one lamp, FIG. 2 is a pulse waveform diagram of an example of the pulse generating circuit 1 of FIG. 1, and FIG. FIG. 3 is a circuit diagram of a lamp burnout detection circuit in a case where there are a large number of lamps according to an embodiment of the present invention.

In the figure, 1 is a pulse generation circuit, 2 is a judgment circuit, 3 is a NOT circuit, 30 is a NOR circuit, 4 is an AND circuit, 10.11 is a lamp, 40.41 is a drive circuit equipped with a lamp separation circuit and a detection circuit, R1°R2 are resistors, R3 and R4 are high resistances, Tri is a drive transistor, Tr2 is a transistor, D■ is a diode, and ■ is a power supply.

The pulse generating circuit 1 generates a pulse as shown in the example of FIG. 2, and in this example, the pulse width is IQOms,
The pulse interval is set to 5 minutes, and this pulse is generated by a transistor Tr for disconnecting the lamp of the drive circuit 40, which includes a lamp disconnection circuit and a detection circuit, from the drive circuit.
2 and also to the AND circuit 4 of the determination circuit 2.

Transistor Tr2 is 100m5 where this pulse is generated manually.
It is on during this period, and off at other times.

In order to turn on the lamp, when an H level signal is input from terminal a, the drive transistor Tri is turned on, and the lamp 10. j drive transistor Tr 1. A current flows through the diode D1 and the lamp 10 lights up, but while the pulse of width Looms is being generated from the pulse generating circuit 1, the transistor Tr2 is turned on, the drive transistor Tri is turned off, and the lamp 10 is turned on from the drive circuit. The lamp 10 is disconnected, the lamp 10 goes out, and an H level voltage is generated at point X, which is the sum of the resistance of the lamp 10 and the high resistance R3, and the resistance voltage division ratio of the high resistance R4, and is inverted at the knot circuit 3. However, since the input is at the L level, nothing is output from the AND circuit 4.

Note that while the 100 ms pulse is not input, the transistor Tr2 is off, the lamp 10 is lit, and the level at the Although the level is input, at this time, since the repulse from the pulse generating circuit 1 is not input to the AND circuit 4, nothing is output from the AND circuit 4.

However, when the lamp 10 is out, the voltage 6V is cut off, so the voltage level at point X becomes the ground level regardless of the presence or absence of pulse power, and the H level is given to the AND circuit 4, generating a pulse. When the pulse from circuit 1 is input to AND circuit 4, this pulse is ANDed,
The determination circuit 4 outputs a signal indicating that the lamp is burnt out.

Therefore, even when the lamp 10 is in use when it is lit, a burnt out lamp can be detected.

The above description has been made based on the case where there is a signal to light the lamp IO, but even if there is no signal, if the lamp is burnt out in the same manner as above, the determination circuit 4 outputs a signal indicating that the re-lamp is burnt out.

Therefore, even when the lamp is in use, lamp burnout can be detected without turning on the slump.

Note that when the lamp 10 is turned on by a human signal, the lamp 10 will be turned off while the Looms pulse from the Dodo Lux generation circuit 1 is being input, but this turn-off time will change once every 5 minutes.
Because it is short at 00m3, it appears to the naked eye to remain lit, and the display a
Noh is not affected.

Of course, the pulse interval may be changed to 5 minutes, 10 minutes, etc.

In this way, even if the lamp 10 is in use with the lamp 10 lit, or when the lamp 10 is extinguishing smoke, it is possible to detect a burnout of the lamp when sending out pulses, so it is easy to use the lamp. It can be detected early when the battery is out, and power consumption can be extremely reduced.

In an actual display device, the number of lamps is large, but in this case, as shown in FIG. 3, the drive circuit for the lamps 10, 11, etc. is the same as the lamp disconnection circuit and detection circuit shown in FIG. 1. Drive circuit with circuit 40.4
1. If the knot circuit 3 in FIG. 1 is replaced by a NOR circuit 30 as shown in FIG. It can be detected by the same operation.

〔Effect of the invention〕

As explained in detail above, according to the present invention, power consumption is extremely small, labor is not required, and when a lamp burns out, it can be detected quickly.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a lamp burnout detection circuit according to an embodiment of the present invention when there is only one lamp, FIG. 2 is a pulse waveform diagram of an example of the pulse generating circuit 1 of FIG. 1, and FIG. FIG. 3 is a circuit diagram of a lamp burnout detection circuit in a case where there are a large number of lamps according to an embodiment of the present invention. In the figure, ■ is a pulse generation circuit, 2 is a judgment circuit, 3 is a not circuit, 4 is an ant circuit, 10.11 is a lamp, 30 is a NOR circuit, 40.41 is a drive circuit equipped with a lamp disconnection circuit and a detection circuit. , R1 and R2 are t resistors, R3 and R4 are high resistances, Tri is a drive transistor, Tr2 is a transistor. 14 yo 2.9 oh 5, I
■ indicates the power supply.

Claims (1)

[Claims] A drive circuit that lights up a lamp upon reception of an input signal includes a pulse generation circuit that sends out pulses at predetermined time intervals, a circuit that disconnects the lamp from the drive circuit using the pulses, and a detection circuit that detects whether or not the lamp is conductive. A lamp burnout detection circuit comprising: a determination circuit that determines whether the lamp is burnout by detecting the presence or absence of conduction of the lamp when a pulse is output from the pulse generating circuit.