JPS62113390A - Constant luminous power controller - 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 relates to a constant light amount control device, and more particularly to a constant light amount control device that can control the light amount of an ultra-high pressure lamp such as an ultra-high pressure xenon lamp to a constant value.

(Prior Art) For example, an ultra-high pressure xenon lamp is used as a simulated sunlight when testing the surface deterioration of dyes, paints, and other materials due to irradiation with natural sunlight, that is, the light resistance. (Refer to Japanese Unexamined Patent Publication No. 150389/1989) It is desirable that such an ultra-high pressure xenon lamp has a constant light amount. Conventionally, therefore, the light emitted from an ultra-high-pressure lamp is guided to a photoelectric converter through an optical fiber, and the lamp current is controlled based on the light amount signal (current signal) output from the photoelectric converter. This was done to ensure that a constant amount of light was obtained.

In addition, since the internal pressure of the ultra-high pressure lamp is, for example, 10 atmospheres or more, the transparent glass body covering the light emitting part is made of, for example, quartz glass, which has excellent light transmittance and pressure resistance. Ru.

Furthermore, when ultra-high-pressure lamps reach their scheduled operating time, the accumulation of distortion in the transparent glass body caused by the high heat during use reaches almost the permissible limit, and the encapsulated electrode (for example, tungsten) evaporates, causing the transparent glass body to evaporate. It becomes attached as dirt to the inner surface.

As a result, when an ultra-high-pressure lamp is used for longer than the scheduled operating time, that is, beyond the lamp life, the transparent glass body, that is, the lamp, may explode or the surrounding There is a risk of damage to equipment.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

In other words, light emitted from an ultra-high pressure lamp is guided to a photoelectric converter using an optical fiber. The drawback is that the amount of light from an ultra-high pressure lamp can only be detected partially and cannot be accurately detected over a wide range.

In addition, because linear optical fibers have weak mechanical strength, care must be taken when replacing them, and since optical fibers are expensive, they rarely have the disadvantage of increasing the cost of the entire device. .

Furthermore, in conventional light intensity constant control devices, although the light intensity of the ultra-high pressure lamp was controlled to be constant as described above, there was no means for automatically detecting the lamp umbrella. Ta.

For this reason, there are cases where the lamp is used beyond its lamp life, and in such cases, the lamp may explode.

The present invention has been made to solve the above-mentioned problems.

(Means and effects for solving the problems) In order to solve the above problems, the present invention provides a method for supplying light emitted from an ultra-high pressure lamp to a photoelectric converter via a quartz glass rod. It is distinctive in that it did so.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, a lamp power supply 1 supplies lamp current to an ultra-high pressure lamp 2, such as an ultra-high pressure xenon lamp.

The quartz glass rod 3 reflects the light from the ultra-high-pressure lamp 2 turned on by the supply of the lamp current on its nonconforming surface 3 a and guides it to the photoelectric converter 4 . Note that the internal angle θ of the reflective surface 3a is 45°.
The surface is unprocessed.

The photoelectric converter 4 generates and outputs a light amount signal (current value signal) corresponding to the amount of light supplied via the quartz glass rod 3. The comparator 6 compares the light amount target value signal supplied from the light amount target value generation circuit 7 and the light amount signal supplied from the photoelectric converter 4, and outputs a difference signal a.

The light amount control circuit 8 uses the difference signal a to control the difference signal @a.
The impedance is controlled so that 0. The lamp current detection circuit 9 detects the actual lamp current value supplied to the ultra-high pressure lamp 2 using the lamp current detection section 9a.
Then, the lamp current value signal S is supplied to the second comparator 10.

The second comparator 10 compares the maximum current value signal supplied from the maximum current value setting circuit 11 with the lamp current value signal, and when the lamp current value reaches the maximum current value, a lamp life judgment signal is sent. Output C.

Next, the operation of this embodiment will be explained.

When lamp current is supplied from the lamp power source 1 to the ultra-high pressure lamp 2, the ultra-high pressure lamp 2 is lit. A portion of the light generated by the lighting is reflected by the reflective surface 3a, passes through the quartz glass rod 3, and is supplied to the photoelectric converter 4.

The photoelectric converter 4 generates and outputs a light amount signal corresponding to the supplied light amount, and supplies it to the comparator 6. The comparator 6 compares the light amount target value signal supplied from the light amount target value generation circuit 7 and the light amount signal supplied from the photoelectric converter 4, and outputs a difference signal a.

Note that the light amount target value set by the light amount target value generation circuit 7 is determined depending on the use of the ultra-high pressure lamp 2 and how constant the light amount is to be.

The difference signal a is supplied to the light amount control circuit 8.

As a result, the light amount control circuit 8, by the difference signal @a,
The impedance is controlled so that the difference signal a becomes O.

That is, the light amount control circuit 8 is controlled so that the impedance increases when the light amount signal output from the photoelectric converter 4 is larger than the light amount target value set by the light amount target value generation circuit 7. , and for the light intensity target value,
When the light amount signal is small, the impedance is controlled to decrease. Therefore, the amount of light from the ultra-high pressure lamp 2 is always a constant value.

By the way, as described above, when the ultra-high pressure lamp 2 approaches the scheduled usage time, that is, the lamp life, the sealed electrode evaporates and becomes attached as dirt to the inner surface of the transparent glass body.

As a result, assuming that the lamp current is constant, the amount of light emitted to the outside gradually decreases depending on the degree of adhesion of dirt. Therefore, in this embodiment, the lamp current of the extra-high pressure lamp 2 is increased by the control operation described above.

In this embodiment, such a lamp current is detected by the lamp current detection section 9a, and the lamp current detection circuit 9 outputs a lamp current value signal.

The second comparator 10 receives the lamp current value signal S and compares the maximum current value signal supplied from the maximum current value setting circuit 11 with the lamp current value signal S. As a result, when the lamp current value reaches the maximum current value, a lamp life determination signal C is output.

The maximum current value set by the maximum current value setting circuit 11 is determined as follows. In other words, when the reduction in light intensity due to the adhesion of dirt is corrected by increasing the lamp current, it is necessary to experimentally determine in advance what lamp current value will be reached when the ultra-high pressure lamp 2 is almost at the end of its lamp life. I search for it.

The lamp current value thus determined is determined to be the maximum current value.

The lamp life determination signal C obtained as described above can be used for any desired purpose. To give an example,
In response to the lamp life judgment signal C, a warning lamp is lit or an alarm is sounded to warn that the lamp life has come to an end, or together with or separately from the above-mentioned warning, It becomes possible to turn off the lamp power supply.

In the above description, in order to control the lamp current, the difference signal a is supplied to the light amount control circuit 8 to change the impedance of the light amount control circuit 8. However, in the present invention, it is not necessarily necessary to provide the light amount control circuit 8. For example, the difference signal a may be supplied to the lamp power supply 1 and the lamp current may be controlled in the lamp power supply 1 by any known suitable method.

Moreover, in the above, in order to obtain the lamp life judgment signal C, 1
In the configuration of the range A surrounded by the dotted chain line, the lamp current value signal S is compared with the maximum current value. However, the present invention is not limited to such a configuration.

For example, if the range is configured as shown in Figure 2,
Lamp life determination signal C can be obtained.

That is, in FIG. 2, the lamp current value signal is supplied to the current change rate detection circuit 20. The current change rate detection circuit 20 samples and holds the supplied lamp current value signal at predetermined time intervals. Then, it outputs a difference signal between the current value and the previous value of the lamp current value, that is, a current change rate signal.

The third comparator 21 receives the current change rate signal and compares the reference current change rate signal supplied from the reference current change rate setting circuit 22 with the current change rate signal. As a result, when the current change rate reaches the reference current change rate, a lamp life judgment signal C is generated and output.

Note that when the current change rate becomes equal to or higher than the reference current change rate, it can be determined that the lamp has reached the end of its life.As the lamp life approaches its end, dirt builds up rapidly, and as a result, the current change rate (current This is because the degree of increase in amount increases rapidly.

In other words, in this embodiment, the rate of change in current near the end of the lamp life is experimentally determined and the rate of change is set as the reference current rate of change, so that when the lamp life approaches, A lamp life determination signal C will be output.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

(1) Since the light emitted from the ultra-high pressure lamp is guided to the photoelectric converter using a quartz glass rod with a reflective surface at the tip, the light detection range becomes wider. This has the effect of accurately detecting the amount of light over a wide range. The quartz glass rod has strong mechanical strength and does not deform, making it easy to handle and replace. Furthermore, since the quartz glass rod is inexpensive, it has the effect of reducing the cost of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention. FIG. 2 is a block diagram showing a modification of the area A in FIG. 1... Lamp power supply, 2... Ultra-high pressure lamp, 3...
Quartz glass rod, 3a...Reflecting surface, 4...Photoelectric converter, 6...Comparator, 7...Light amount target value generation circuit, 8.
...Light amount control circuit, 9...Lamp current detection circuit, 10
...Second comparator, 11...Maximum current value setting circuit,
20... Current change rate detection circuit, 21... Third comparator, 22... Reference current change rate setting circuit

Claims (1)

[Claims] (1) an ultra-high-pressure lamp, a lamp power source that supplies lamp current to the ultra-high-pressure lamp, means for generating and outputting a light intensity signal according to the light intensity when the ultra-high-pressure lamp is lit, a light intensity target value signal and the light intensity; and a means for controlling the lamp current so that the difference signal becomes 0 based on the difference signal. The generation/output means includes a quartz glass rod having a reflective surface at its tip that propagates a portion of the light amount emitted from the ultra-high pressure lamp along its length, and a light amount signal in response to the light amount caused by the reflection. A constant light amount control device comprising a photoelectric converter that generates and outputs light.