JPH023279Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention extends the life of the light source by brightening the light source only when necessary and lowering the illuminance of the light source at all times when illuminating with a light source such as a light bulb. The present invention relates to a lighting device configured to do so.

Generally, in painting robots, welding robots, etc., the areas where painting or welding is required, the distance between the work part and the workpiece, the width, etc. are monitored using a television camera attached to the robot's arm. A light source for a television camera is attached to a device having such a configuration. When the robot needs to be monitored by a television camera when operating the robot, the illuminance of the light source is increased based on the execution program, and the illuminance is normally lowered to extend the life of the light source. Furthermore, in this type of robot, a light source failure detection circuit is provided because a light source failure has a large effect on the operating rate.

However, in the conventional technology, when the light source is not in use, the illuminance of the light source is lowered and a preheating resistor is used as a preheating bleeder, which only performs preheating, and a resistor for detecting light source outage is placed between the power source and the light source. When the television camera is not in use, the preheating resistor is inserted in series and the preheating resistor is energized to reduce the illuminance of the light source and only preheat the light source. The structure is such that a light source outage is detected based on a change in the light source.

However, in the above conventional technology,
First, a preheating resistor and a resistance for detecting light source failure are required, and there is a drawback that the voltage loss due to the resistor for detecting light source failure, which is always energized, is large. In addition, since the resistance value of the light source failure detection resistor is about 3 to 10% of that of the light source as a load, the voltage or current detection sensitivity is low and the circuit configuration is complicated.

The purpose of the present invention is to improve the drawbacks of the prior art as described above.A light source is connected in series to a power source, and a resistor for preheating the light source and a resistor for disconnecting the light source are connected between the power source and the light source. A resistor that also serves as a detection resistor is inserted, and a switch that is closed or opened by an external bright signal or dark signal is connected in parallel to the resistor, and when a dark signal is input to the switch, the switch is activated. By providing a light source burnout detection circuit that detects light source burnout by comparing the voltage across the resistor when the resistor is open, the resistor can serve as a preheating resistor and a light source burnout detection resistor. The present invention provides a lighting device in which the resistance can be set to a resistance value of 20 to 80% of the load.

The present invention will be described below along with embodiments shown in the drawings. In the figure, 1 is an AC power source, 2 is a transformer, the AC power source 1 is connected to the primary side of the transformer 2, and the secondary side is provided with a light bulb 3 as a light source.
The AC power source and the light bulb 3 are connected in series. A resistor 4 is inserted between the secondary side of the transformer 2 and the light bulb 3, which serves as a preheating resistor and a light source burnout detection resistor. 5 is a relay consisting of an excitation coil 5A and a normally open contact 5B, one end of the excitation coil 5A is connected to the power supply +V, the other end is connected to the bright/dark signal terminal 7 via a knot circuit 6, and the contact 5B is connected to a resistor. 4
connected to both ends. Here, the bright/dark signal terminal 7 outputs a bright signal (hereinafter referred to as
The not circuit 6 outputs a "bright signal H") and a dark signal (hereinafter referred to as a "dark signal L"), and when the bright signal H is input, the not circuit 6 outputs an "L" level signal. A current flows from the power supply +V to the exciting coil 5A, and the exciting coil 5A is excited and closes the contact 5B. On the other hand, when the dark signal L is input to the not circuit 6, the output of the not circuit 6 becomes "H" level and has the same potential as the power supply +V, no current flows through the excitation coil 5A, and the contact 5B is opened.

8 is a differential amplifier that outputs a sine wave by inputting the voltage across the resistor 4; 9 is a rectifier circuit that converts the output of the differential amplifier 8 into a DC voltage; the output from the rectifier circuit 9 is is input to the positive input terminal of the comparison circuit 10. On the other hand, 11 and 12 are resistors for voltage division, and each of the resistors 11 and 12 is connected in series between the power supply +V and the ground.
The voltage at the branch point 13 between them is inputted to the negative input terminal of the comparator circuit 10 as a reference voltage. Here, when the light bulb 3 is lit regardless of whether it is bright or dark, a voltage is generated across the resistor 4, so
Comparison circuit 10 via differential amplifier 8 and rectifier circuit 9
When the lamp 3 is turned off, no voltage is generated across the resistor 4, so the comparator circuit 10 outputs an "H" level signal by comparing it with the reference resistance of the negative input terminal. Outputs the signal.

Reference numeral 14 denotes a not circuit into which the signal from the bright/dark signal terminal 7 is input. It is connected to the input side of the AND circuit 15 via. Therefore, the bright signal H from the bright/dark signal terminal 7
When the signal is being input, the output side of the NOT circuit 14 is at the "L" level, and the output from the AND circuit 15 is at the "L" level. On the other hand, when the dark signal L is input from the bright/dark signal terminal 7, the not circuit 1
The output side of 4 becomes "H" level, and the delay circuit 1
After the delay time of 8, the output side of the AND circuit 15 becomes "H"
level. Note that the delay circuit 18 is provided to prevent malfunctions due to a delay in the drive time of the relay 5, a voltage change in the resistor 4, and the like.

Furthermore, the input side of the AND circuit 20 is connected to the output terminals of the above-mentioned comparison circuit 10 and AND circuit 15, and its output side serves as a light source out signal output terminal 21. This serves as an input signal for the alarm device and the robot control circuit (none of which are shown). Here, AND circuit 20
outputs an “H” level when the output from the comparator circuit 10 is at an “H” level while the output of the AND circuit 15 is at an “H” level;
Conversely, if the output from the comparison circuit 10 is at the "L" level even though the output from the AND circuit 15 is at the "H" level, the output from the AND circuit 20 becomes at the "L" level and the light bulb 3 burns out. detect that

Since the present invention is configured in this way, when the dark signal L is output from the bright/dark signal terminal 7, the excitation coil 5A of the relay 5 is demagnetized and the contact 5B is opened, and the power is transferred from the AC power source 1 to the transformer 2, resistance 4
However, since the voltage across the resistor 4 is high, the illuminance of the light bulb 3 decreases, making it dark. In this state, the dark signal L from the bright/dark signal terminal 7 is input as an "H" level signal to the AND circuit 20 via the NOT circuit 14 and the AND circuit 15, so if the light bulb 3 is already burnt out or When the voltage is cut off midway, the voltage across the resistor 4 becomes zero, the output of the comparator circuit 10 becomes "L" level, and the output of the AND circuit 20 also becomes "L" level. Therefore, by changing the output from the AND circuit 20 from "H" to "L" level, it is possible to warn that the light source is out, and to prevent the robot from starting when the light source is out. It can also be used as an input signal to the control circuit. Also,
Since the voltage across the resistor 4 is detected when the relay 5 is open, the voltage can be detected reliably. Furthermore, by inserting the delay circuit 16, it is possible to prevent malfunctions due to delayed response of the relay 5.

In addition, in the above embodiment, the relay 5 consisting of the excitation coil 5A and the contact 5B is used as a switch connected in parallel with the resistor 4, but
Of course, it may be constructed from a non-contact switch such as a semiconductor circuit. Further, the light source 3 is not limited to a light bulb, and various light sources such as a fluorescent lamp can be used.

The lighting device according to the present invention is as described in detail above, and the resistor inserted between the power source and the light source can be used as a preheating resistor for the light source and a light source cut-off detection resistor, and Since the resistor controls the brightness of the light source, a resistor having a resistance value of about 20 to 80% of the light source can be used, and voltage detection sensitivity can be increased.

[Brief explanation of the drawing]

The figure is a circuit diagram of a lighting device according to the present invention. 1... AC power supply, 3... Light source, 4... Resistor, 5
... Relay, 6, 14 ... Note circuit, 7 ... Light/dark signal terminal, 10 ... Comparison circuit, 15, 20 ...
AND circuit, 18...Delay circuit, 21...Light source out signal output terminal.

Claims (1)

[Scope of utility model registration request] A light source is connected in series to a power source, and a resistor is inserted between the power source and the light source that serves as a preheating resistor for the light source and a light source failure detection resistor, and the circuit is closed by an external bright or dark signal. A switch to open or open is connected in parallel to the resistor, and when a dark signal is input to the switch and the switch is open, the voltage across the resistor is compared to detect the light source cut-off. A lighting device equipped with a detection circuit.