Electric heating – Metal heating – By arc
Patent
1997-09-03
1999-04-20
Mills, Gregory L.
Electric heating
Metal heating
By arc
21912173, B23K 2606
Patent
active
058955887
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a controller of a laser marking machine.
BACKGROUND ART
In a laser marking machine, it is arranged that a printing pattern of a divided image is displayed on a liquid crystal display screen (in which a transparent scattering type liquid crystal is employed) which serves as a liquid crystal mask; a laser beam is then scanned over the liquid crystal display screen and a printing position is moved so that the printing pattern of the divided image displayed on the liquid crystal display screen is printed at a position corresponding to this divided image on an article on which the printing pattern is to be printed.
In order to shorten the marking time and improve the efficiency of the operation, what is called "white space skipping" control is performed such that, of the printing pattern on the liquid crystal screen, only printing portions are scanned, non-printing portions being skipped without scanning.
By means of such "white space skipping" control, the benefit is obtained that the area of the scanning field can be reduced so the marking time can be shortened to an extent corresponding to the unscanned area of the field.
However, portions which are irradiated by the laser beam and portions which are not irradiated by the laser beam are interspersed, creating temperature differences within the plane of the liquid crystal mask.
The relationship between the transmittance of the liquid crystal and the drive voltage depends on temperature. If the drive voltage is fixed, the transmittance of portions of higher temperature increases. The drive voltage is in fact constant in the plane of the liquid crystal mask.
Temperature irregularities in the plane of the liquid crystal mask therefore appear as marking irregularities, adversely affecting the quality of the marking.
Thus, if "white space skipping" control is performed, a temperature distribution is created within the liquid crystal mask plane, producing unevenness of marking. Also, if "white space skipping" control is not performed, although unevenness of marking is suppressed, there is no way to shorten the marking time.
With the foregoing in view, it is an object of the present invention to achieve simultaneously both shortening of the marking time and suppression of irregularities in marking.
DISCLOSURE OF THE INVENTION
As mentioned above, it is an object of the present invention to achieve simultaneously both shortening of the marking time and suppression of irregularities in marking.
This object is achieved by the first aspect of the invention and second aspect of the invention as follows.
Specifically, the first aspect of this invention consists in a laser marking machine comprising: display means for dividing a printing pattern of an original image to be printed onto an article into divided-image printing patterns and displaying the divided-image printing patterns on a liquid crystal display screen; scanning means for effecting scanning of a laser beam generated by a laser light source over the liquid crystal display screen; and moving means for moving the printing position in such a manner that the printing pattern of the divided image displayed on the liquid crystal display screen is printed at a position on the article to be printed corresponding to the divided image in question, characterized in that the display means displays the printing pattern of the divided image on the liquid crystal display screen such that the divided image is classified into a non-printing region and a printing region, and, if a non-printing region is in an upper region that is scanned first when the liquid crystal display screen is displayed, this non-printing region is omitted and scanning is commenced by the scanning means on the liquid crystal display screen from a printing region following this non-printing region; and the moving means corrects movement amount of the printing position of the printing pattern by an amount of the non-printing region that was omitted and starts movement to a marking position of a next d
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International Search Report in PCT/JP95/00555 mailed May 28, 1996.
Matsumura Yukinori
Misugi Koji
Soda Akihiko
Komatsu Ltd.
Mills Gregory L.
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