METHOD FOR CONTROLLING RADIATION EMITTING FROM ONE OR MORE TUBULAR LAMPS IN AN EXPOSURE APPARATUS

Abstract

There is provided method for controlling radiation emitting from one or more tubular lamps in an exposure apparatus for exposing a photosensitive element to the radiation. The method involves adjusting an adjustable ballast connected to the one or more lamps thereby adjusting the power received by the one or more lamps, wherein adjusting the ballast of the one or more lamps is based on the actual temperature and radiation of the one or more lamps.

Claims

1. A method for controlling radiation emitting from one or more tubular lamps in an exposure apparatus for exposing a photosensitive element to the radiation, said apparatus comprising a central control unit and an adjustable ballast connected to the one or more lamps for adjusting the power W (ballast) received by the one or more lamps, wherein the method comprises the step of adjusting the ballast of the one or more lamps is based on a pre-characterization of the one or more lamps, said pre-characterization determining the output of the one or more lamps has been determined as a function of lamp current (A) and/or temperature T, optionally over the life time t, of the one or more lamps, whereby the central control unit is configured to adjust the ballast of the one or more lamps based on the basis of said pre-characterization to achieve a lamp output in the range of 15 to 25 mWatt/cm2.

2. The method of claim 1, wherein the output of the one or more lamps has been determined as a function of lamp current (A) and temperature T.

3. The method of claim 1, wherein the output of the one or more lamps has been determined over the life time t of the one or more lamps.

4. The method of claim 1, wherein the temperature of the one or more lamps is measured in a distance from the one or more lamps of 0-30 cm.

5. The method of claim 1 further comprising placing the photosensitive element on an exposure bed, and exposing the photosensitive element to the radiation irradiating from the one or more lamps after adjusting the power to the ballast.

6. The method of claim 1, wherein the target irradiance is 18 to 22 mWatt/cm2.

7. The method of claim 1, wherein the one or more lamps comprises a plurality of tubular lamps that are adjacent and parallel to each other, and further comprising measuring irradiance emitting from the one or more lamps in proximity (i.e. 2-4 cm) to the one or more lamps.

8. The method of claim 1, wherein the exposure apparatus for exposing a photosensitive element to the radiation has a cooled bed configuration.

9. An exposure apparatus comprising: an adjustable ballast connected to one or more tubular lamps for adjusting the power W (ballast) received by the one or more lamps, a control unit for adjusting the ballast of the one or more lamps based on a pre-characterization of the one or more lamps, wherein the output of the one or more lamps has been determined as a function of lamp current (A) and/or temperature T, optionally over the life time t, of the one or more lamps, whereby the central control unit is configured to adjust the ballast of the one or more lamps based on the basis of said pre-characterization to achieve a lamp output in the range of 15 to 25 mWatt/cm2.

10. The exposure apparatus according to claim 9, wherein the control unit is configured to implement a method for controlling radiation emitting from one or more tubular lamps in an exposure apparatus for exposing a photosensitive element to the radiation said apparatus comprising a central control unit and an adjustable ballast connected to the one or more lamps for adjusting the power W (ballast) received by the one or more lamps, wherein the method comprises the step of adjusting the ballast of the one or more lamps is based on a pre-characterization of the one or more lamps, said pre-characterization determining the output of the one or more lamps has been determined as a function of lamp current (A) and/or temperature T, optionally over the life time t, of the one or more lamps, whereby the central control unit is configured to adjust the ballast of the one or more lamps based on the basis of said pre-characterization to achieve a lamp output in the range of 15 to 25 mWatt/cm2.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 shows two lamp configurations of the present invention.

[0017] FIG. 2 shows graphs of lamp current adjustments over the duty cycle.

[0018] FIG. 3 shows UV-A output over lamp temperature, at different lamp current levels.

[0019] FIG. 4 shows a block diagram over the exposure system.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The invention will now be explained in more detail with reference to an embodiment in which the exposure device comprises one or more of the following functional elements: [0021] A carrier plate for the photosensitive substrate which is temperature-controlled in order to control the substrate temperature during exposure. [0022] A cooling system used to control the carrier plate temperature (cooled bed). [0023] A transparent carrier plate for the photosensitive substrate in order to allow double-sided exposure. [0024] A set of adjacent light bulbs, mounted on top and/or below the photosensitive substrate. [0025] Minimum one temperature sensors to monitor and to control the lamp temperature. [0026] A cooling system used to control the lamp temperature. [0027] Minimum one UV-light sensor in order to monitor and to control the UV energy applied to the substrate. [0028] Minimum one ballast used to provide an adjustable lamp current to the lamp(s). As an alternative, a ballast with a fixed lamp current output can used. The fixed lamp current level is based on the below mentioned dataset. [0029] A central control unit that provides the input to the one or more adjustable ballasts, in order for them to provide the optimum lamp current according to the below mentioned dataset. [0030] A generic dataset established for each lamp type and/or batch, defining the UV emission level as a function of time, lamp current, and temperature.

[0031] This dataset is then used to set the optimum lamp current provided by the adjustable ballast, depending on actual output status of the lamp, which is derived from the generic dataset

[0032] Examples for such generic dataset are as follows:

[0033] Referring to FIG. 1 there is shown the relation between the lamp current provided by the ballast, and the resulting UV-A output. The two lamp configurations shown (specific ballast+specific lamp type, X+Y) exhibit different characteristics. This generic information may be used to adjust the lamp current to an optimum level, depending on the UV-A output requirement. In the configuration X, the lamp current for maximum output would be set to appr. 2.1 A. If the extended lifetime is desired the optimum lamp current could be set to appr. 1.8 A.

[0034] Referring to FIG. 2 there is shown a drop (in % from starting level) in UV-A output over time, at 100% duty cycle. All 4 configurations indicate individual characteristics, which can be shown as logarithmic functions. Based on these functions, the lamp current can be adjusted over duty cycle time in order to compensate for the shown drop.

[0035] Referring to FIG. 3 there is shown UV-A output over lamp temperature, at different lamp current levels. This temperature characteristic is varying slightly from lamp type to lamp type. Such knowledge is important in order to determine and ensure optimum temperature conditions for each individual lamp type.

[0036] Finally, for illustrative purposes reference is made to FIG. 4, which is a block diagram over the exposure system.