Electric heating – Metal heating – By arc
Reexamination Certificate
1999-12-07
2001-10-09
Elve, M. Alexander (Department: 1725)
Electric heating
Metal heating
By arc
C219S121690, C219S121670, C219S121740
Reexamination Certificate
active
06300593
ABSTRACT:
TECHNICAL FIELD
This invention relates to apparatus and a method for laser scribing a coated substrate and has particular utility for laser scribing semiconductor and metallic contact layers on a glass sheet substrate in connection with manufacturing photovoltaic panels.
BACKGROUND ART
Pulsed laser beams have previously been utilized to scribe through a coating on a substrate such as is done in manufacturing photovoltaic panels. Two approaches have been used to accommodate the relatively fast pulse rates of current YAG lasers in comparison to the speed at which the substrates can be moved. One approach called flying optics requires precise mechanical motion of optic elements along a rail as well as requiring precise mechanical motion of the substrate being scribed, and this approach consequently requires acceleration and deceleration of relatively massive components. Another approach uses galvonometer deflectors but equipment of this type is not yet commercially available for scribing coated substrates the size of photovoltaic panels.
DISCLOSURE OF INVENTION
One object of the present invention is to provide improved apparatus for laser scribing a coated workpiece by splitting the laser beam to provide multiple scribes during movement of the substrate.
In carrying out the above object, the apparatus for laser scribing a coated substrate includes a laser source for generating a pulsed laser beam having laser pulses with sufficient power to form ablations through a coating on the substrate. A polygonal mirror of the appatus is mounted for rotation to reflect the laser pulses of the laser beam toward the substrate to split the laser beam and provide spaced ablations through the coating. A conveyor of the apparatus moves the substrate along a direction of conveyance so the ablations formed by the laser pulses reflected from the rotating polygonal mirror overlap each other and form a set of spaced scribes through the coating on the substrate and extending parallel to the direction of conveyance.
The apparatus includes at least one lens through which the laser pulses are passed and directed toward the substrate to provide the ablations through the coating on the substrate. In one embodiment, the apparatus includes a plurality of focusing lenses through which the laser pulses are passed and directed toward the substrate to provide the ablations through the coating on the substrate. In another embodiment, the apparatus includes a field flattening lens through which the laser pulses are passed and directed toward the substrate to provide the ablations through the coating on the substrate.
Another embodiment of the apparatus includes a plurality of fiber optics through which the laser pulses are passed for passage toward the substrate to provide the ablations through the coating on the substrate. This fiber optic embodiment also includes at least one lens through which the laser pulses are passed from the fiber optics and directed toward the substrate to provide the ablations through the coating on the substrate.
The apparatus can also include a laser detector for detecting the rotational location of the rotating polygonal mirror.
Other embodiments of the apparatus also each include a controller for generating a second set of laser pulses that are referenced to the first set of laser scribes to generate a second set of scribes through the coating on the substrate in a spaced relationship from each other and from the first set of scribes. In one such embodiment, the controller includes a trigger beam actuator for generating trigger pulses referenced to the first set of scribes to generate the second set of laser pulses that are directed toward the substrate to scribe the second set of scribes that are spaced on the substrate from each other and from the first set of spaced scribes. In another such embodiment, the controller includes a detector that compares the locations of the ablations provided by the second set of laser pulses with respect to the first set of scribes and provides adjustment as necessary to provide the desired spacing between the sets of scribes.
Another object of the present invention is to provide an improved method for laser scribing a coated substrate by splitting a pulsed laser beam to provide a set of spaced scribes.
In carrying out the immediately preceding object, the method for laser scribing a coated substrate is performed by generating a pulsed laser beam having laser pulses with sufficient power to ablate through a coating on the substrate. A polygonal mirror is rotated to reflect the laser pulses of the laser beam toward the substrate to split the laser beam and form spaced ablations through the coating. The substrate is moved along a direction of conveyance so the ablations formed by the laser pulses overlap each other and form a set of spaced scribes through the coating on the substrate and extending parallel to the direction of conveyance.
In performing the laser scribing method, the laser pulses are preferably reflected from the rotating polygonal mirror and passed through at least one lens to provide the ablations through the coating on the substrate. In one practice, the laser pulses are reflected from the rotating polygonal mirror and focused through a plurality of focusing lenses to provide the ablations through the coating on the substrate. In another practice, the laser pulses are reflected from the rotating polygonal mirror and passed through a field flattening lens to provide the ablations through the coating on the substrate.
In another practice of the method, the laser pulses are passed through a plurality of fiber optics toward the substrate to provide the ablations through the coating on the substrate. In this practice, the laser pulses are passed from the fiber optics to and through at least one lens toward the substrate to provide the ablations through the coating on the substrate.
It is also possible for the method to utilize a laser detector to detect the rotational position of the polygonal mirror.
In another practice of the laser scribing method of this invention, a second set of laser pulses is generated with reference to the first set of scribes to provide a second set of scribes in a spaced relationship from each other and from the first set of scribes in the coating on the substrate. In one practice, this is performed by trigger pulses that are generated with reference to the first set of scribes to actuate generation of the second set of laser pulses that provide the second set of laser scribes spaced on the substrate from each other and from the first set of spaced scribes. In another practice, the second set of laser pulses is generated to provide overlapping ablations that provide the second set of scribes in the coating on the substrate and the locations of the overlapping ablations provided by the second set of laser pulses are detected and compared to the first set of scribes and any necessary adjustment is performed to in order to provide a desired spacing of the second set of scribes from each other and from the first set of scribes in the coating on the substrate.
The laser scribing method of the invention has particular utility for forming scribes through a semiconductor coating on a substrate and particularly when the substrate is a glass sheet.
In addition, the laser scribing method has particular utility for forming scribes through a metallic coating on a substrate and particularly when the substrate is a glass sheet.
The objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings.
REFERENCES:
patent: 4180822 (1979-12-01), Hudson et al.
patent: 4500771 (1985-02-01), Miller
patent: 4568409 (1986-02-01), Caplan
patent: 4877939 (1989-10-01), Duley et al.
patent: 5430816 (1995-07-01), Furuya et al.
Brooks & Kushman P.C.
Elve M. Alexander
First Solar LLC
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