JPH0247835B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a multicolor light emitting diode (hereinafter referred to as a monochrome LED) having a plurality of monochrome light emitting diodes (hereinafter referred to as monochrome LED), which is used in a display panel etc. to display status, etc. This invention relates to an improvement in a lamp test circuit that performs a lamp test to determine whether each single-color LED (hereinafter referred to as a multi-color LED) emits light.

These LEDs are important for displaying the status of the device. For example, if an LED is disconnected, the discovery of a device failure may be delayed and the problem may progress to a serious problem.

Therefore, it is necessary to periodically perform lamp tests on all LEDs.

It is desirable that a lamp test circuit that performs such a lamp test be small and inexpensively constructed.

[Conventional technology]

FIG. 2 is a circuit diagram of a conventional lamp test circuit.

In the figure, 1 and 2 are drivers, 3 and 4 are multi-color LEDs,
5 to 8 are knot circuits, 9 to 12 are diodes, 1
3 and 14 are red LEDs, 15 and 16 are green LEDs,
SW1-1 and SW1-2 are interlocking switches, SW2-
1 and SW2-2 are interlocking switches, RL1 and RL2 are relays, rl1-1, rl1-2, rl2-1, rl2-
2 is the contact of relay RL1, RL2, G1, G2, R
1 and R2 are terminals, and V1 and V2 are power supplies.

In Fig. 2, terminals R1, R2, G1, G
When inputting H level signals from each of 2,
The respective outputs of the knot circuits 5 to 8 of drivers 1 and 2 are at ground level, and the multicolor LEDs 3 and 4
The red LEDs 13 and 14 and the green LEDs 14 and 15 emit light, respectively.

For example, when an H level signal is input from R1 and G1, the red LED 13 and the green LED 15 emit light, and the multicolor LED 3 emits a multicolor mixture of red and green.

Therefore, if a high level signal is input from terminals R1, R2, G1, G2 depending on the state, multi-color
Since the LEDs 3 and 4 emit red light, green light, or multiple colors, they can display the status.

Now red LED 13, 14, green LED 15, 16
For example, when performing a lamp test on terminals R1, R
H level signal is input to 2 and red LED13,1
4 is emitting light, green LEDs 15 and 16
When you perform a lamp test by emitting light, multicolor LED3,
4 emits multiple colors, making it difficult to see whether green light has been emitted or not.

For this reason, in the conventional example, relays RL1 and RL2 are provided, and when interlocking switches SW2-1 and SW2-2 are turned on, relay RL2 operates and contact RL2
-1 and 2-2 open, red LEDs 13 and 14 go out,
Since only the green LEDs 15 and 16 emit light, it is possible to reliably determine whether or not they are emitting light, allowing a reliable lamp test to be performed.

Also, when H level signals are input to terminals G1 and G2 and green LEDs 15 and 16 are emitting light, red
When the interlocking switches SW1-1 and SW1-2 are turned on in order to make the LEDs 13 and 14 emit light and perform a lamp test, the relay RL1 operates and the contact RL1-
1, 1-2 are open, green LEDs 15, 16 are off,
Since only the red LEDs 13 and 14 emit light, it is possible to know with certainty whether or not they are emitting light, making it possible to perform a reliable lamp test.

[Problem that the invention seeks to solve]

However, many multi-color LEDs are used on display panels, etc.
Conventional lamp test circuits require twice as many contacts as the number of multicolor LEDs, and a relay with these contacts is required, making the lamp test circuit large. Another problem was that it was expensive.

The present invention has been made in view of the following points, and its purpose is to provide a compact and inexpensive lamp test circuit that does not use a relay.

[Means for solving problems]

The problem mentioned above is that the multicolor light emitting diode is equipped with a driver that independently drives each of the monochrome light emitting diodes that make up the multicolor light emitting diode, and an AND circuit that is connected to the input terminal of the driver and controls the output of the driver. When performing a lamp test, by turning on the AND circuit connected to the input terminal of the driver that drives the single-color light-emitting diode, the driver lights up the single-color light-emitting diode and turns on the other single-color light-emitting diode. This problem is solved by the lamp test circuit of the present invention, in which the AND circuit connected to the input terminal of the driver that drives the lamp is turned off to cut off the light emission signal.

[Effect]

According to the present invention, when performing a lamp test by causing one single-color LED to emit light, the AND circuit blocks the light-emission signal to the other single-color LED to stop the light emission, so that a reliable lamp test can be performed. It becomes possible.

〔Example〕

FIG. 1 is a circuit diagram of a lamp test circuit according to an embodiment of the present invention.

In the figure, 17 to 20 are AND circuits, R11, R21
indicates a resistor, and the same reference numerals indicate the same functions throughout the figures.

In the case of Fig. 1, the AND circuits 17 to 20 are usually
, H is connected from the power supply V1 through resistors R11 and 21.
Since the level is given, terminals R1, R2,
When an H level signal is input from G1 and G2, the corresponding LED emits light as in the conventional case.

Now, for example, when H level signals are input to terminals R1 and R2 and red LEDs 13 and 14 are lit,
In order to make the green LEDs 15 and 16 emit light and perform a lamp test, use interlocking switches SW2-1 and SW2-2.
When turned on, the interlocking switch SW of resistor R11
The 2-1 side is grounded, and the AND circuits 17 and 18
The H level signals input from the terminals R1 and R2 are cut off, and the not circuits 5 and 6 of the driver 1 are
The output becomes H level, and the red LEDs 13 and 14
disappears, the green LEDs 15 and 16 emit light, and a lamp test can be performed to ensure that the green LEDs 15 and 16 emit light.

Conversely, when H level signals are input to terminals G1 and G2 and green LEDs 15 and 16 are emitting light,
In order to make the red LEDs 13 and 14 emit light and perform a lamp test, use interlocking switches SW1-1 and SW1-2.
When turned on, the interlocking switch SW of resistor R21
The 1-1 side is grounded, and the AND circuits 19 and 20
The H level signals input from the terminals G1 and G2 are cut off, and the not circuits 7 and 8 of the driver 2 are
The output becomes H level, and the green LEDs 15 and 16
disappears, the red LEDs 13 and 14 emit light, and a lamp test can be performed to ensure that the red LEDs 13 and 14 emit light.

Therefore, the relay shown in FIG. 2 is not necessary, and the lamp test circuit can be constructed in a small size and at low cost.

In addition, in this example, two LEDs are used to display multiple colors.
LED is used, but multiple colors using 3 or more LEDs
Even in the case of LEDs, a switch may be provided to set the AND circuit of inputs for other LEDs to L level in conjunction with a switch that causes one monochrome LED to emit light.

〔Effect of the invention〕

As described in detail above, according to the present invention, there is an effect that a lamp test circuit can be constructed in a small size and at low cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a lamp test circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional lamp test circuit. In the figure, 1 and 2 are drivers, 3 and 4 are multicolor light emitting diodes, 5 to 8 are knot circuits, and 9 to 1.
2 is a diode, 13 and 14 are red light emitting diodes, 15 and 16 are green light emitting diodes, 17 to 2
0 is an AND circuit, SW1-1, SW1-2 are interlocking switches, SW2-1, SW2-2 are interlocking switches, RL1, RL2 are relays, rl1-1, rl1-2,
rl2-1, rl2-2 are contacts, R1, R2, G1,
G2 is a terminal, R11 and R21 are resistors, V1 and V2
indicates power supply.

Claims (1)

[Scope of Claims] 1. A lamp test circuit for a multicolor light emitting diode having a plurality of monochrome light emitting diodes, comprising: a driver that independently drives each of the monochrome light emitting diodes among the multicolor light emitting diodes; and an output from the driver. is connected to the input terminal of
One input terminal is provided with a two-input AND circuit, into which a light emission signal that causes each monochromatic light emitting diode to emit light is input, and the other input terminal is input with a control signal that controls passing or blocking of the light emission signal, When performing a lamp test for one monochrome light emitting diode, by turning on an AND circuit connected to the input terminal of a driver that drives the monochrome light emitting diode, the monochrome light emitting diode is caused to emit light by the driver; A lamp test circuit characterized in that an AND circuit connected to an input terminal of a driver that drives the other monochromatic light emitting diode is turned off to cut off a light emitting signal.