JPH0266891A - Lamp blowoff sensor circuit - Google Patents

Abstract

PURPOSE:To prevent misjudgement under dimming mode by furnishing a power supply for sensing eventual lamp blowing-off, and nullifying the sensing current in case the filament of an incandescent electric bulb on the irradiated side has blown off. CONSTITUTION:A supply current from a power supply 7 for lighting-up is superposed with a minute current fed from another power supply 10 for sensing of lamp blowoff, and current is supplied to an incandescent electric bulb 3 on the irradiated side. The power supply 10 is to supply minute current to the electric bulb 3, which is thereby not lighted. When the filament of the electric bulb 3 severs, the two--side voltage of a resistance R inserted in the line of the power supply 10 will nullify. The sensing voltage proportions to the minute current, and when it nullifies, a current sensor circuit 11 gives an abnormality signal to a changeover circuit 19, and a relay RY in the circuit 19 is turned on. The incandescent electric bulb 3 on the irradiated side is changed over to another incandescent electric bulb 2 on the standby side, which elimimates discontinuity in a light source device and misjudgement under the dimming mode, and lamp severance can be accurately sensed at all times.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lamp burnout detection circuit for detecting lamp burnout in an incandescent light bulb using a filament, such as a halogen lamp.

[Prior Art] Generally, incandescent light bulbs with high illuminance are often used as light sources for illumination for camera photography. However, incandescent light bulbs have a relatively short lifespan. When an incandescent light bulb reaches the end of its lifespan, it either stops emitting light due to the filament breaking, or some of the filaments become short-circuited, causing a phenomenon in which the illuminance changes significantly. If the incandescent bulb stops emitting light or changes in illuminance, it becomes difficult to take pictures, so it is necessary to detect this and replace the incandescent bulb. Particularly when used on a production line, detection of abnormal ramps is important because the line stops moving.

Note that the phenomenon of filament fusing during the life of the lamp may be half-broken or completely blown, so two detection methods are required. In the present invention, detection of lamp burnout when the lamp is completely blown out is adopted.
-I will do so.

Conventionally, when the filament completely melts, the impedance becomes infinite and no current flows, so the current supplied by the lighting power supply that supplies power to the incandescent bulb is detected, and when this current reaches zero, the lamp It was designed to detect breaks. However, this conventional method has the disadvantage that it is only possible to detect lamp burnout when the lamp is not lit or when the voltage supplied to the lamp is lowered due to dimming.

For example, in the case of a light source device for robot vision,
Power is not constantly supplied to the lamp from the lighting power supply (to extend the life of the lamp, turn off the power frequently if it returns to the standby position even when the robot is in operation). I'm trying to turn off the lights.

In addition, normally, in a light source device, in order to keep the reflected light from the subject constant regardless of the type of subject being photographed with the camera,
Dimming control is performed by changing the power supply voltage of the lamp according to the reflected light from the subject.

For this reason, there may be no problem when the lamp voltage is high, but as the lamp voltage decreases, the current supplied to the lamp also decreases.

Even when the power goes out or the voltage becomes low,
There was a problem with the conventional method that it incorrectly judged that the current was zero.

[Problem to be solved by the invention 1 As described above, detecting the lamp current of the lighting power source,
Conventional lamp burnout detection circuits detect lamp burnout when this detection current is zero. Under these conditions, it will also be determined that the lamp is burnt out, so the drawback is that it cannot detect the lamp burnout under these conditions.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art by passing a current for detection different from that for lighting in parallel through an incandescent lamp, so that detection can be performed even when the lamp is off or at low voltage. The object of the present invention is to provide a break detection circuit.

Means for Solving the Problems 1 The lamp burnout detection circuit of the present invention changes the power supply voltage of a lighting power supply that supplies power to an incandescent light bulb using a filament, such as a halogen lamp, in order to vary the light intensity of the incandescent light bulb. In addition, in a light source device in which power supply to an incandescent light bulb is intermittent, a power supply for detecting lamp burnout that superimposes a minute current for detecting melting of the filament on the current supplied by the lighting power supply to the incandescent light bulb; The lamp is equipped with a current detection circuit that detects the current supplied to the incandescent light bulb from the burnout detection power source and outputs a lamp burnout signal when the current reaches zero.

1 Effect] Separately from the lighting power source, a detection current is always supplied to the incandescent light bulb from a lamp burnout detection power source.

Therefore, even when the lights are turned off and the current is no longer supplied from the lighting power supply, or during dimming when the output voltage of the lighting power supply decreases, the current for detection becomes zero or becomes so small that it becomes undetectable. It won't happen. Therefore, the detection current becomes zero only when the filament melts, and a lamp burnout signal is output from the current detection circuit, so that the filament melting can be detected even when the lamp is turned off or when the voltage is low.

[Example] 4~ Embodiments of the present invention will be described below with reference to FIG.

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and particularly illustrates a two-lamp type fiber light source device constituting a visual section mounted on a robot.

Reference numeral 1 denotes a lamp house installed in the movable part of the robot, and inside thereof two halogen lamps 2 and 3 with mirrors of the same characteristics are provided.

One is the standby side or reserve side, and the other is the irradiation side or main side.

At the front of the lamp house 1 overlooking each of the halogen lamps 2 and 3, an italite guide for an optical fiber bulb is provided for illuminating a subject 6 located 1ii11 away from the lamp house 1. Its base end is divided into two branches, which join in the middle to form a single branch, and the tip extends to a position near a camera, for example, a CCD camera 5.

This light guide 4 is arranged so that the subject 6 is illuminated with the same illuminance regardless of whether the light is emitted from the Haloken lamp 2 or 3. They are bundled to be mixed. Light Guy 1" 4 (for cars) is used because it cuts infrared rays, makes the optical path flexible/pull, and in addition, the tip can be shaped into any shape, whether it's a link or a line.

A power line for each halogen lamp 2.3 is drawn out from the rear surface of the lamp house 1 and connected to a lamp lighting power source 7 attached to a fixed part. Although a switch regulator having an overcurrent prevention function is used here as the power supply 7, it may be a non-recess regulator as long as it has an overcurrent prevention function. The purpose of providing an overcurrent prevention function is to protect the circuit elements of the power supply itself.

A light receiver 9 such as a phototype auto FD generates a voltage proportional to the intensity of the amount of light reflected from the subject 6, and this voltage is applied to an analog voltage generation circuit 8 for lamp voltage control.

Here, the lamp voltage control analog voltage generation circuit 8 outputs a dimming command to the lamp lighting power source 7 in the form of an analog voltage to maintain the reflected light of the subject 6 at a constant level regardless of the type of subject 6. Add to analog input terminal for voltage control. This allows the CCD camera 5 to always capture a constant amount of reflected light.

The negative output line of the lamp lighting type 'tA7 is commonly connected to one terminal of each Haloken lamp 2, 3, while the positive output line is connected to either the other terminal of lamp 2 or 3 via relay RY. It is designed to be connected selectively to both.

The relay RY is controlled by a current detection circuit 11 that detects a current supplied to the lamp 2 or 3 from a power supply 10 for lamp burnout detection, which is provided separately from the lamp lighting type rA7.

The lamp burnout detection power source 10 is a power source for supplying a minute current to the lamp 2 or 3 to detect filament blowout of the lamp 2 or 3.

Although this power source 10 is a constant voltage source in the illustrated example, it may be a constant current source. The reason why a minute current is passed is to prevent the lamp from lighting up. In order to supply a minute current to the lamp 2 or 3 by superimposing it on the supply current without causing a backflow to the lighting power supply 7, the lamp burnout detection power supply 10 connects its negative power supply line to the lamp lighting type. #7
while the diode D2 is commonly connected to the negative power supply line of
The positive power supply line drawn out through the terminal is commonly connected to the positive power supply line of the lighting power supply 7 drawn out through the tie-off I"Di. In other words, the current of both power supplies 7°10 does not flow backwards to each other. , the cathodes of tie autos DI and D2 are commonly connected so that they are supplied to the lamp 23 in a superimposed manner.

The current detection circuit 11 detects a detection voltage proportional to the minute current taken out from both ends of the resistor R inserted in the positive power supply line of the power supply 10 for lamp burnout detection, and detects when the detection voltage is zero, that is, the current is zero. Switching circuit 19 for lamp burnout abnormality signal
Output to. In addition, when the power supply 10 for lamp burnout detection is a constant current source, the current detection circuit 11 can also be a voltage detection circuit that detects an abnormally high voltage generated in the constant current source due to an open circuit. .

The switching circuit 19 is composed of a T-type flip-flop 12 and a relay RY, and is configured to switch the current detection circuit 11 by an abnormal signal.
The 1'' type flip-flop 12 connected to the terminal is inverted, the relay RY is turned on, and the positive power line is switched from the irradiation side lamp 3 to the standby side lamp 2. At the same time, an alarm lamp 13 attached to the lamp lighting power source 7 is turned on by the abnormality signal. Note that an alarm may be sounded instead of the alarm lamp.

Next, the operation of the above-described configuration will be explained.

Initially, relay RY is off and switched to the irradiation side lamp 3 side. Therefore, the lamp 3 to which electric power is supplied from the lamp lighting power supply 7 becomes the irradiation light source, and the light is guided to the light guide 4 and is directed from the tip of the light guide to the subject 6.
is irradiated.

In such a normal state, the voltage of the lamp lighting type rA7 is set to Vl.
, If the voltage of the power supply 10 for lamp burnout detection is V2, if v2>vl, a minute current I expressed by the following equation flows in the positive power line of the power supply 10 for lamp burnout detection.

I□= 1V2- (V, -VDI) -VD2+ /
However, VDI and VD2 are the forward voltages of the diodes Di and D2, and the current detection resistor R is selected to have a resistance value considerably higher than the impedance of the lamp filament.

When the filament of the lamp 3 reaches the end of its life and is completely blown out, the impedance on the cathode side of the tie auto D2 inserted on the power supply 10 side for detecting lamp breakage becomes almost infinite, and the lamp is turned on. power supply 7
Regardless of the mode state, the lamp current flowing from the power supply 10 for lamp burnout detection to the lamp 3 at the value shown by the above equation becomes 12%. As a result, the voltage drop across the resistor R becomes zero, and the current detection circuit 11 outputs an abnormal signal ``l''''.Then, T type free.

Since the flip-flop 12 is reversed and becomes H", and the relay RY is turned on, the power supply is automatically switched from the illumination side lamp 3, which had been supplied with power from the lamp lighting power supply 7, to the standby side lamp 2, and the standby mode is started. The side lamp 2 becomes a new source of light.At the same time, the alarm lamp 13 sounds, so the worker is aware of the lamp abnormality.Therefore, the worker uses the time when the robot is stopped to detect the abnormality. Replace Haroken lamp 3 with a new lamp.

On the other hand, when the backup lamp 2 that has been powered on and switched to the irradiation side becomes abnormal, the current detection circuit 11 is activated again in the same way.
An abnormality signal is output from the lamp, and this time, the F type flip-flop 12 is set to L', so the relay RY is turned off, and the lamp 3 that has been replaced is switched to the newly replaced one.

- As mentioned above, in this embodiment, the lamp lighting power supply 7
In addition to the above, a power supply 10 for detecting lamp breakage is provided to supply a minute current for detection to the lamps 2 and 3 independently of the lamp current of the power supply 7 for lamp lighting, so that the lamp burnout detection power supply 10 can be used to supply a small current for detection to the lamps 2 and 3. , the light source device equipped with the robot does not receive power from the lamp lighting type 17 when the robot is stopped during operation (even when the lamp is turned off, the detection current for lamp burnout continues to flow through the lamp). In addition, even if the power supply voltage of the lamp lighting power source 7 is lowered due to dimming, and the value of the current supplied from the lamp lighting type 7 to the lamp 2 or 3 becomes smaller. Similarly, it is possible to continue flowing a current large enough to detect lamp burnout.

Therefore, by constantly detecting the current of the lamp burnout detection power supply 10 by the current detection circuit 11, lamp burnout can be reliably detected.

In addition, the diodes DI and D2 have a common cathode and are connected to both power supplies so that they do not flow backwards, and the current supplied to the lamp from the power supply for lamp burnout detection is a very small current, so that it can be detected without disturbing the dimming control. There is no inconvenience such as lighting due to electric current.

II. Effects of the Invention] According to the present invention, the power supply for detecting lamp breakage is provided separately from the power supply for lighting, so that the detection current becomes zero only when the filament is fused, so there is no need to interrupt or adjust the light source device. Misjudgments in the light mode can be avoided, and lamp burnout can be accurately detected regardless of the mote.

[Brief explanation of the drawing]

FIG. 1 shows a light source device to which an embodiment of the lamp burnout detection circuit of the present invention is applied. In the figure, 2 is a standby lamp (incandescent bulb), 3 is a halogen lamp (incandescent bulb) on the irradiation side, 6 is the subject, 7 is a power source for lamp lighting, and 8 is for lamp voltage control as a dimming level generator. 10 is a power supply for lamp burnout detection; 11 is a current detection circuit; and 19 is a switching circuit.

Claims (1)

[Claims] 1. In a light source device that supplies power to an incandescent lamp such as a halogen lamp, in which the power supply voltage of a lighting power supply that supplies power to an incandescent lamp that uses a filament changes in order to vary the amount of light of the incandescent lamp, and in which the power supply to the incandescent lamp is intermittent, the filament A lamp burnout detection power supply that superimposes a minute current for detecting fusing on the lighting power supply current and supplies it to the incandescent bulb, and a lamp burnout detection power supply that detects the current supplied to the incandescent bulb from this lamp burnout detection power supply. , and a current detection circuit that outputs a lamp burnout signal when the current becomes zero.