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

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:

• 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.

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:

• 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.

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:

• 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.

A semiconductor laser control apparatus comprising:

• 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.