Method and apparatus for extending and confirming the service life of semiconductor laser of bar code reader by detecting current increase corresponding to temperature of semiconductor laser
First Claim
1. A semiconductor laser control apparatus comprising:
- a semiconductor laser;
a semiconductor laser control circuit, coupled to said semiconductor laser, for controlling a drive current of said semiconductor laser so that a specific light quantity is output from said semiconductor laser;
drive current measuring means for measuring an actual drive current of said semiconductor laser;
temperature measuring means for measuring an actual temperature of said semiconductor laser;
memory means for storing at least one initial drive current value of said semiconductor laser for the specific light quantity and corresponding temperature of said at least one initial drive current value;
detection means for comparing the actual drive current value of said semiconductor laser measured by said drive current measuring means with the at least one initial drive current value corresponding to the actual temperature when the actual drive current is measured; and
warning means for generating an alarm predicting the expiration of service life of said semiconductor laser, when the actual drive current value exceeds the corresponding at least one initial drive current value by a specified percentage.
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Accused Products
Abstract
A semiconductor laser control method and apparatus includes a semiconductor laser, a semiconductor laser control circuit, a drive current measuring unit, a detection unit, a warning unit, and a memory unit. The memory unit stores initial drive current values and corresponding temperatures. The detection unit performs a step of comparing an actual drive current value measured by the drive current measuring unit with the initial drive current value corresponding to an actual temperature. The warning unit performing a step of generating an alarm predicting the expiration of service life of the semiconductor laser, when the actual drive current value exceeds the corresponding initial drive current value by a specified percentage. Consequently, the near expiration of the service life of the semiconductor laser can be confirmed and therefore render the operational effects such as replacement of the semiconductor laser, without causing any hindrance to the operation.
136 Citations
30 Claims
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1. A semiconductor laser control apparatus comprising:
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a semiconductor laser; a semiconductor laser control circuit, coupled to said semiconductor laser, for controlling a drive current of said semiconductor laser so that a specific light quantity is output from said semiconductor laser; drive current measuring means for measuring an actual drive current of said semiconductor laser; temperature measuring means for measuring an actual temperature of said semiconductor laser; memory means for storing at least one initial drive current value of said semiconductor laser for the specific light quantity and corresponding temperature of said at least one initial drive current value; detection means for comparing the actual drive current value of said semiconductor laser measured by said drive current measuring means with the at least one initial drive current value corresponding to the actual temperature when the actual drive current is measured; and warning means for generating an alarm predicting the expiration of service life of said semiconductor laser, when the actual drive current value exceeds the corresponding at least one initial drive current value by a specified percentage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor laser control apparatus which repeatedly lights and extinguishes a semiconductor laser at a specified ratio, which continuously remains on when specified information is detected in a reflected light from an object to be radiated, and which repeatedly lights and extinguishes at the specified ratio when the specified information is not detected even after the specified time has passed from said information detection timing, said semiconductor laser control apparatus comprising:
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first drive means for controlling the lighting of said semiconductor laser to obtain a first light quantity; second drive means for controlling the lighting of said semiconductor laser to obtain a second light quantity larger than the first light quantity; and control means for controlling the lighting by said first drive means for continuous lighting and changing over to said second drive means for repeated lighting and extinguishing. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A bar code reader device, for reading data from a bar code label and supplying the data to a point-of-sale terminal, having a semiconductor laser control apparatus, said semiconductor laser control apparatus comprising:
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a semiconductor laser; a semiconductor laser control circuit, coupled to said semiconductor laser, for controlling a drive current of said semiconductor laser so that a specific light quantity is output from said semiconductor laser; drive current measuring means for measuring an actual drive current of said semiconductor laser; temperature measuring means for measuring an actual temperature of said semiconductor laser; memory means for storing at least one initial drive current value of said semiconductor laser for the specific light quantity and corresponding temperature of said at least one initial drive current value; detecting means for comparing the actual drive current value of said semiconductor laser measured by said drive current measuring means with the at least one initial drive current value corresponding to the actual temperature when the actual drive current is measured; and warning means for generating an alarm predicting the expiration of service life of said semiconductor laser, when the actual drive current value exceeds the corresponding at least one initial drive current value by a specified percentage. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A bar code reader device, for reading the data of a bar code label and supplying the data to a point-of-sale terminal, having a semiconductor laser control apparatus which repeatedly lights and extinguishes a semiconductor laser at a specified ratio, which continuously remains on when specified information is detected in a reflected light from an object to be radiated, and which repeatedly lights and extinguishes at the specified ratio when the specified information is not detected even after the specified time has passed from said information detection timing, said semiconductor laser control apparatus comprising:
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first drive means for controlling the lighting of said semiconductor laser to obtain a first light quantity; second drive means for controlling the lighting of said semiconductor laser to obtain a second light quantity larger than the first light quantity; and control means for controlling the lighting by said first drive means for continuous lighting and changing over to said second drive means for repeated lighting and extinguishing. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A semiconductor laser control apparatus comprising:
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a semiconductor laser driven by a drive current; means for determining the actual drive current of said semiconductor laser; means for determining an actual temperature of said semiconductor laser; and means for predicting the expiration of service life of said semiconductor laser based on the actual drive current value, the actual temperature and a corresponding at least one initial drive current value for a predetermined light quantity and corresponding temperature. - View Dependent Claims (30)
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Specification