Electric heating – Metal heating – By arc
Patent
1996-08-07
1998-03-31
Walberg, Teresa J.
Electric heating
Metal heating
By arc
21912173, 21912185, 349 4, 349161, B23K 2606
Patent
active
057341451
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of driving a liquid crystal mask marker, and particularly relates to a method of driving a liquid crystal mask marker when the liquid crystal mask produces an image.
BACKGROUND ART
Conventionally, liquid crystal mask markers have been devices for marking an image on a workpiece surface by irradiating a laser beam onto a liquid crystal mask, which has been provided with a pattern to be marked on the workpiece, and by irradiating the transmitted light onto the workpiece surface. These liquid mask markers are broadly divided into a collective irradiation type, which collectively irradiates, for example, an expanded laser beam onto an image, and a raster irradiation type which irradiates a fine laser beam onto an image as the fine laser beam is being deflected by a XY deflector. Though both types have advantages and disadvantages, the raster irradiation type, which has a complicated structure and control program compared to the collective irradiation type, can reduce the size of the laser oscillator, and as a result, can obtain safety at a high level, since a small laser beam intensity can be used, so that the raster irradiation type is considered to be preferred for the future.
As a method of controlling a liquid crystal mask marker, a known method for improving marking accuracy provides that the time for oscillating the laser of a laser oscillator is after the time for applying to the liquid crystal mask a voltage for displaying an image (for example, Japanese Patent Application Laid-open No. 64-1 1088). This method has been proposed, paying attention to the fact that it takes some time for an image to have a specified contrast (hereinafter referred to as "the completion of an image production") when a voltage for displaying an image is applied to the liquid crystal mask, and that marking accuracy is reduced when a laser beam is irradiated onto the image during the voltage application to the liquid crystal mask.
Recently, there has been a demand for a liquid crystal mask marker which can mark on mass-produced products at a high speed and with high accuracy, as seen from the marks such as a production number, a pattern or the like, for example, on an IC board. While the marking accuracy is improved in the aforementioned conventional method of controlling a liquid crystal mask marker, the marking accuracy is improved, but the laser beam is not oscillated until after the liquid crystal mask completes the production of an image; therefore the conventional method of controlling a liquid crystal mask marker has a disadvantage in that the marking speed is not improved.
SUMMARY OF THE INVENTION
The present invention is made in order to eliminate the disadvantage of the conventional art, and an object of the present invention is to provide a method of driving a liquid crystal mask marker which can increase the marking speed while marking accuracy is maintained.
The first aspect of the method of driving a liquid crystal mask marker in accordance with the present invention has a characteristic in that a laser beam is irradiated onto a non-light-permeable portion of the liquid crystal mask, which is a portion other than a liquid crystal surface, such as a non-light-permeable surface and/or a non-liquid-crystal surface of the liquid crystal mask, before the completion of an image production when the image is produced on the liquid crystal mask. The non-light-permeable surface of the aforementioned liquid crystal mask can be a liquid crystal electrode member of the liquid crystal mask.
The aforementioned structure is made by utilizing the fact that the speed, at which the light transmittivity of a liquid crystal rises, increases when the temperature of the liquid crystal rises; that is, the time required for producing an image is shortened when the temperature of the liquid crystal is raised. Then, in order to promote a rise in the temperature of the liquid crystal, the laser beam is irradiated onto a portion which does not transmit light such as the non-lig
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Ichihara Masashi
Matsumura Yukinori
Mori Akira
Tsuda Yukihiro
Komatsu Ltd.
Mills Gregory L.
Walberg Teresa J.
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