Electric heating – Metal heating – By arc
Patent
1995-05-23
1997-02-25
Evans, Geoffrey S.
Electric heating
Metal heating
By arc
21912169, 21912173, 2191218, B23K 2606, B41J 2465, G02B 2608
Patent
active
056056419
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to method and apparatus for performing laser marking on a plurality of objects which are continuously fed for marking.
RELATED BACKGROUND ART
An ink jet marking method has hitherto been widely used for marking patterns, composed of characters, symbols, diagrams and figures, on workpieces such as, for example, metals, synthetic resins, ceramics, papers, and fabrics, which are manufactured in factory lines. This system is intended to carry out marking while changing relative positions of a workpiece and an ink jet nozzle by a transfer unit as disclosed, for example, in Japanese Patent Application Disclosure Gazette SHO. 57-14981, and therefore conjunctive operation of the transfer unit and the ink jet unit is essentially required.
Along with a trend in recent years of downsizing workpieces, such as semiconductor products, the marks to be used have had to become smaller with greater preciseness. Therefore, a laser marking apparatus has been used lately instead of the ink jet system. The conventional laser marking apparatus has been such that a laser beam, obtained from a laser oscillator through a polarizer, is used to raster-scan a mask surface, and the laser beam which passes through the mask is irradiated onto a workpiece.
However, in such laser marking apparatus, the laser beam which passes through the mask is polarized toward a workpiece transfer line, a workpiece is temporarily stopped when it reaches a laser irradiation area, which is fixed, and marking is performed by irradiating the laser beam onto the surface of this stationary workpiece. Therefore this system includes a problem in that the transfer line has to be stopped for marking on each workpiece, and improvement of the production time will be impaired.
SUMMARY OF THE INVENTION
An object of the present invention, made in view of the above problem, is to provide method and apparatus for performing laser marking on an object which is fed without stopping during laser beam marking, thus improving production efficiency.
The present invention provides a laser marking apparatus comprising a first polarizer for polarizing a laser beam from a laser oscillator for raster-scanning, a mask capable of displaying a specified pattern through which a raster-scanning laser beam from the first polarizer is selectively transmitted, a second polarizer for further polarizing the raster-scanning beam which has been transmitted through the mask and irradiating the further polarized laser beam onto the object for marking the pattern onto the object, wherein the second polarizer is provided with a reflection mirror which reflects the laser beam which has been transmitted through the mask, and a movable lens which receives the reflected laser beam and irradiates the reflected laser beam for marking, the movable lens being mounted on a moving mechanism which moves in synchronism with a workpiece transfer speed. The reflection mirror comprises a first mirror, which reflects the laser beam passing through the mask, and a second mirror, which can reflect the previously reflected beam to the movable lens, and the direction of reflection of the first mirror is changeable between toward the second mirror and toward the movable lens. This reflection mirror can comprise a movable mirror, which directly reflects the laser beam passing through the mask and is movable horizontally; a rotary mirror, which reflects the reflected beam to a movable lens and is rotatable on a flat surface; and a fixed mirror, which can receive the reflected beam by movement of the movable mirror and is able to reflect the reflected beam to the rotary mirror; the direction of reflection of the reflection mirror being changeable, between toward the rotary mirror and toward the fixed mirror, in accordance with the position of the movable mirror. In addition, the moving mechanism which mounts the movable lens is formed by an orthogonal two axis planar moving mechanism, one axial direction of which is aligned with the workpiece transfer direction,
REFERENCES:
patent: 4746202 (1988-05-01), Perilloux et al.
patent: 5309273 (1994-05-01), Mori et al.
Chiba Teiichiro
Yoshida Koji
Evans Geoffrey S.
Komatsu Ltd.
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