JPS636879Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an exposure discharge lamp lighting circuit.

Generally, a discharge lamp such as a high-pressure mercury lamp is used as a light source for exposure, but in the exposure process such as printing patterns required in the manufacture of integrated circuits, the amount of exposure to the exposed object is controlled to a strictly appropriate value. In order to achieve this, it is important to control the lighting state of the exposure light source so that a stable and constant amount of light emission is always obtained from the light source.

An example of a conventional exposure discharge lamp lighting circuit having such a function is shown in FIG. In this example, a power detector 4 is provided to detect the power supplied to the discharge lamp 3 from a power supply mechanism 2 connected to a power supply circuit 1, and a signal from the power detector 4 and a reference value setting mechanism 5 are provided. A power control mechanism 7 is configured such that a comparison amplifier 6 receives a reference signal from the comparison amplifier 6, and a power supply control signal from the comparison amplifier 6 is applied to the power supply mechanism 2, thereby controlling the reference signal to a required magnitude. By setting the power to the discharge lamp 3, the power supplied to the discharge lamp 3 is controlled so as to always have a constant value, which is equal to the rated power of the normal discharge lamp 3.

According to such a configuration, a constant amount of power is supplied to the discharge lamp 3, but the amount of light emitted from the discharge lamp 3 is actually always constant even if the power supplied to it is constant. Rather, due to various causes such as changes in the environment surrounding the discharge lamp 3, such as changes in ambient temperature, the amount of light emitted changes, making it impossible to always achieve the desired exposure.

On the other hand, as shown in FIG. 2, in place of the power detector 4 in the example of FIG. 1, a photodetector 8 for directly detecting the amount of light emitted from the discharge lamp 3 is provided to constitute the power control mechanism 9. A lighting circuit for a discharge lamp is also known, but in this example, the current supplied to the discharge lamp is generally controlled to decrease or increase in accordance with the increase or decrease in the amount of light emitted from the discharge lamp. Therefore, due to the characteristics of the discharge lamp 3, the amount of light emitted by the discharge lamp 3 does not match the magnitude of the current supplied to the discharge lamp 3, for example, at the initial stage of lighting. If this is not done and the amount of light emitted is much smaller than the amount of light emitted in the fully lit state, the current supplied to the discharge lamp 3 will be controlled to increase significantly. As a result, the current exceeds the allowable current value of the discharge lamp 3, resulting in the discharge lamp 3 being destroyed.

Based on the above-mentioned circumstances, the present invention enables the discharge lamp constituting the light source for exposure to be brought into a fully lit state safely, and also stabilizes the amount of light emitted from the discharge lamp to a constant state during the fully lit period. An object of the present invention is to provide an exposure discharge lamp lighting circuit that can be maintained.

An embodiment of the present invention will be described below with reference to the drawings.

In the present invention, as shown in FIG. 3, a photodetector 8 that directly detects the amount of light emitted from the discharge lamp 3 is provided close to the discharge lamp 3, and the signal from the photodetector 8 is amplified. The power supply control signal from the output part c of the comparison amplifier 6 is applied to one input part a of the comparison amplifier 6 via the photodetection signal processing mechanism 10 and the first relay contact ry1, and the power supply control signal from the output part c of the comparison amplifier 6 is applied to the power supply mechanism. 2, the first power control mechanism 11 is configured, and a power detector 4 that detects the power supplied to the discharge lamp 3 from the power supply mechanism 2 is provided, and the signal from the power detector 4 is Second
The power is applied to one input section a of the comparator amplifier 6 through the relay contact ry2, and the comparator amplifier 6 and the power supply mechanism 2 constitute a second power control mechanism 12. When energized, the first relay contact ry1 is closed and the second relay contact ry is opened; when deenergized, the first relay contact ry1 is opened and the second relay contact ry2 is opened. A relay coil RY that closes the relay coil RY is connected to the photodetection signal processing mechanism 10, and the photodetection signal processing mechanism 10 closes the relay coil RY.
When the magnitude of the signal applied to is equal to or greater than the switching reference signal value, that is, the value corresponding to the switching reference light emission amount in which the light emission amount of the discharge lamp 3 is slightly smaller than the required set light emission amount, the relay coil RY is activated. The switch mechanism is constructed such that the switch mechanism is configured such that the Additionally, in the photodetection signal processing mechanism 10, the amplification ratio is adjusted in advance so that the level of the signal therefrom becomes the same level as the level of the signal detected by the power detection mechanism 4.

Since the present invention has the above-described configuration, for example, when the light emission amount of the discharge lamp 3 is smaller than the switching reference light emission amount, such as at the initial stage of lighting start-up of the discharge lamp 3, the relay coil RY is activated by the light detection signal processing mechanism 10. Since the magnitude of the signal applied to is smaller than the switching reference signal value, the relay coil RY is not energized, so the first relay contact ry1 is open and the second relay contact ry2 is closed. During this period, the second power control mechanism 12 by the power detector 4 is activated and the power supplied to the discharge lamp 3 is controlled so as to match the set power. Therefore, by setting the set power to the rated power of the discharge lamp 3, it is possible to prevent the discharge lamp 3 from being supplied with a large amount of power that would increase beyond the rated power, and the discharge lamp 3 can be safely and completely operated. Transition to lighting state. That is, when the lighting state of the discharge lamp 3 is incomplete, the discharge lamp 3 can be turned on by constant power control regardless of the amount of light emitted, and the power supplied to the discharge lamp 3 can be prevented from falling into an overflow state. do not have.

When the discharge lamp 3 is in a fully lit state or in a state close to this, the light emission amount of the discharge lamp 3 becomes the set light emission amount or a state close to this, and a signal is applied from the light detection signal processing mechanism 10 to the relay coil RY. exceeds the switching reference signal value, the relay coil RY is energized and the first relay contact ry1
is closed and the second relay contact ry2 is opened, thereby blocking the second power control mechanism 12 and causing the first power control mechanism 11 to be controlled by the photodetector 8.
is in an operating state, and electric power is supplied to the discharge lamp 3 in such a manner that the amount of light emitted from the discharge lamp 3 is maintained at the set amount of light emitted. In other words, since the electric power supplied to the discharge lamp 3 that is in a fully lit state so that it can be used for the exposure process is controlled based on its actual amount of light emission, a very stable and constant amount of light emission can be obtained. The discharge lamp 3 can be turned on.

In the above embodiment, the comparison amplifier 6 is set to the first
Although the power control mechanism 11 and the second power control mechanism 12 can be used in common, it is of course possible to eliminate the need for such level matching if a comparison amplifier is provided separately for each control mechanism. .

For switching between the first power control mechanism 11 and the second power control mechanism 12, a relay coil is used.
Switching is performed using relay contacts ry1 and ry2 operated by RY, but other switch mechanisms,
For example, a manual switch may be provided for switching. In this case, or even in this case, if a known mechanism is added to display the signal value from the photodetector 8, switching can be performed at the necessary time according to the display, which is convenient for use. become.

As described above, the present invention provides an exposure discharge lamp lighting circuit that can safely bring the lamp into a fully lit state and stably maintain the amount of light emitted from the discharge lamp at a constant level during the fully lit period. can be provided.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams showing an example of a conventional exposure discharge lamp lighting circuit, respectively.
The figure is a block diagram showing an embodiment of the exposure discharge lamp lighting circuit of the present invention. 1...Power source, 2...Power supply mechanism, 3...Discharge lamp, 4...Power detector, 5...Reference value setting mechanism,
6... Comparison amplifier, 8... Photodetector, 10... Photo detection signal processing mechanism, 11... First power control mechanism, 12... Second power control mechanism, RY... Relay coil, ry1... 1st relay contact, ry2...2nd relay contact.

Claims (1)

[Scope of utility model registration request] It includes a power supply mechanism that supplies power to a discharge lamp constituting an exposure light source, and a power detector that detects the power supplied to the discharge lamp from this power supply mechanism, and receives a signal from the power detector. a first power control mechanism that controls the power supplied from the power supply mechanism to the discharge lamp to be equal to a set power; and a photodetector that receives light from the discharge lamp and emits an electric signal; a second power control mechanism that receives a signal from a photodetector and controls power supplied from the power supply mechanism to the discharge lamp so that the amount of light emitted by the discharge lamp is equal to the set amount of light emitted; and the discharge lamp The first power control mechanism is selected when the light emission amount of the discharge lamp is smaller than the switching reference light emission amount that is close to the set light emission amount, and the second power control mechanism is selected when the light emission amount of the discharge lamp becomes equal to or higher than the switching reference light emission amount. A discharge lamp lighting circuit for exposure, comprising a switch mechanism for selecting a power control mechanism.