Electricity: motive power systems – Motor-reversing – Armature or primary circuit control
Patent
1989-02-15
1991-04-09
Arnold, Bruce Y.
Electricity: motive power systems
Motor-reversing
Armature or primary circuit control
350 61, 318127, 250238, 73497, G02B 2610
Patent
active
050059297
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an apparatus including a laser scanner and more particularly to a function for preventing a positional deviation of the apparatus with respect to a machining position of the latter, the positional deviation being caused by variation in temperature of an environment temperature and variation in temperature of a scanner appearing as the apparatus is used.
DESCRIPTION OF THE RELATED ART
As the semiconductor technology is advanced, a variety of elements produced of semiconductor are miniaturized more and more so that a requirement for improvement of the current fine machining technique has been raised up.
Particularly, the laser machining technique has the following advantageous features compared with mechanical machining, electronic machining and chemical machining each of which has been hitherto employed.
(1) It can obtain a very high density of output power.
(2) Since it is non-contact machining, distortion and deformation of a workpiece as seen after completion of machining compared with its state before machining can be suppressed to a minimized level.
(3) It is possible to perform local machining.
(4) Machining can be performed in an arbitrarily selected atmosphere. (Since there is no need of allowing the workpiece to be placed in vacuum, it can be performed at an inexpensive cost compared with the conventional electron beam machining.) In view of the above-mentioned advantageous features, the laser machining has been widely employed in many utilization fields such as marking on the very fine part of a workpiece, trimming of thick film or thin film resistance, annealing of semiconductor and so forth.
An important consideration to be taken during a step of laser machining is to control the position where a laser beam is radiated. To this end, a scanner for which a laser beam is used (hereinafter referred to as a laser scanner) adapted to perform the positional controlling by actuating a mirror is usually used.
This laser scanner is a device which is provided with a position sensor 2 as shown, for example, in FIG. 4 so that the position where a laser beam is radiated is controlled by actuating a mirror 10 by means of a magnetic driver 9 on the basis of positional data detected by the position sensor 2.
With respect to the conventional laser scanner, to assure that positional controlling is exactly performed for the axis of the scanner, there is a need of setting a strict operative condition. Especially, when a laser beam is practically radiated in a factory shop, it is required that its temperature property is particularly stabilized. This is because of the fact that it is required that operation is performed under an environmental condition which could not be presumed by anybody as far as the experimental level is concerned.
To assure that the temperature property is stabilized, such a method that a heater H is arranged round a position sensor 2 in a scanner 1 as shown in FIG. 5 so that the position sensor section is heated up to and maintained at a temperature of about 40.degree. C. at all times by controlling the temperature of an electric power supply source to which the heater H is connected is employed for a laser scanner manufactured, e.g., by General Scanning Corp. (U.S.A.). FIG. 6 illustrates a relationship between a laser scanner b of the type including a heater for the purpose of heating and temperature maintaining and a standard type laser scanner a without any heater used therefor, with respect to temperature and time. As is apparent from the drawing, the laser scanner of the first-mentioned type has an advantageous feature that an operating temperature can be stabilized more reliably than the standard type laser scanner but it has been found that it has the following problems.
(1) It has an elongated period of running time (30 minutes).
(2) The environment temperature required for operation of the laser scanner is restricted in the range of 10.degree. to 28.degree. C.
(3) It is problematic from the viewpoint of environment and practi
REFERENCES:
patent: 3782205 (1974-01-01), Fletcher et al.
patent: 4370019 (1983-01-01), Shirasaki
patent: 4408490 (1983-10-01), Takahashi et al.
Arnold Bruce Y.
Ben Loha
Kabushiki Kaisha Komatsu Seisakusho
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