EP0512541A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Semiconductor laser control apparatus for confirming the service life of semiconductor laser by detecting current increase of the semiconductor laser from initial state thereof
Assignee: Fujitsu Ltd
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Filing: 1992-05-07
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Granted: —
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Expires: 2012-05-07
Abstract
Abstract A semiconductor laser control apparatus comprises a semiconductor laser (2), a semiconductor laser control circuit (3), a drive current measuring unit (20), a detection unit (22), a warning unit (23), and a memory unit (24). The memory unit (24) stores at least one initial drive current values (l ref ) and corresponding temperatures (T ref ). The detection unit (22) compares an actual drive current value (lop, If) measured by the drive current measuring unit (20) with the initial drive current value (l ref ) corresponding to an actual temperature (T). The warning unit (23) generates an alarm of a prediction of the expiration of service life of the semiconductor laser (2), when the actual drive current value (lop, If) exceeds the corresponding initial drive current value (l ref ) as much as a specified percentage. Consequently, the near expiration of the service life of the semiconductor laser (2) can be confirmed and therefore render the operational effects such as replacement of the semiconductor laser without causing any hindrance to the operation.
Inventors
- 👤 Shinichi C/O Fujitsu Limited Sato
- 👤 Hiroaki C/O Fujitsu Limited Katoh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 01:02
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/0014; H01S5/0021; H01S5/068; H01S5/06825; H01S5/0617; H01S5/06804; H01S5/06808; H01S5/0683
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
204 words
A semiconductor laser control apparatus having a semiconductor laser (2), and a semiconductor laser control circuit (3) for controlling a drive current of said semiconductor laser (2) to output a specific light quantity from said semiconductor laser (2), characterized in that said semiconductor laser control apparatus comprises: a drive current measuring means (20) for measuring a drive current (lop, If) of said semiconductor laser (2); a memory means (24) for storing at least one initial drive current values (l ref ) of said semiconductor laser (2) for the specific light quantity and corresponding temperatures (T ref ) of said initial drive current values (l ref ) ; a detection means (22) for comparing an actual drive current value (lop, If) of said semiconductor laser (2) measured by said drive current measuring means (20) with the initial drive current value (l ref ) corresponding to an actual temperature (T) when said actual drive current (lop, If) is measured; and a warning means (23) for generating an alarm of a prediction of the expiration of service life of said semiconductor laser (2), when said actual drive current value (lop, If) exceeds said corresponding initial drive current value (l ref ) as much as a specified percentage.
Claim 2
Dependent Claim
204 words
A semiconductor laser control apparatus having a semiconductor laser (2), and a semiconductor laser control circuit (3) for controlling a drive current of said semiconductor laser (2) to output a specific light quantity from said semiconductor laser (2), characterized in that said semiconductor laser control apparatus comprises: a drive current measuring means (20) for measuring a drive current (lop, If) of said semiconductor laser (2); a memory means (24) for storing at least one initial drive current values (l ref ) of said semiconductor laser (2) for the specific light quantity and corresponding temperatures (T ref ) of said initial drive current values (l ref ) ; a detection means (22) for comparing an actual drive current value (lop, If) of said semiconductor laser (2) measured by said drive current measuring means (20) with the initial drive current value (l ref ) corresponding to an actual temperature (T) when said actual drive current (lop, If) is measured; and a warning means (23) for generating an alarm of a prediction of the expiration of service life of said semiconductor laser (2), when said actual drive current value (lop, If) exceeds said corresponding initial drive current value (l ref ) as much as a specified percentage.
Claim 3
Dependent Claim
33 words
A semiconductor laser control apparatus as claimed in claim 1, wherein said semiconductor laser control apparatus further comprises a temperature measuring means (21) for measuring a temperature (T) of said semiconductor laser (2).
Claim 4
Dependent Claim
89 words
A semiconductor laser control apparatus as claimed in claim 1, wherein said detection means (22) includes: a first drive means for controlling the lighting with a first light quantity; and a second drive means for controlling the lighting with a second light quantity less than said first light quantity, and switches over said first drive means to said second drive means, when said actual drive current value is increased by a specified percentage over said corresponding initial current value while the lighting is controlled by said first drive means.
Claim 5
Dependent Claim
144 words
A semiconductor laser control apparatus repeating lighting and extinguishing of a semiconductor laser (2) at a specified ratio, continuously remaining on when a specified information is detected in a reflection light from an object to be radiated, and repeating lighting and extinguishing at said specified ratio when the following information is not detected even after the specified time has passed from said information detection timing, wherein said semiconductor laser control apparatus comprises: a third drive means for controlling the lighting of said semiconductor laser (2) with a third light quantity; a fourth drive means for controlling the lighting of said semiconductor laser (2) with a fourth light quantity larger than the third light quantity; and a control means for controlling the lighting by said third drive means in continuous lighting and changing over to said fourth drive means in repetition of lighting and extinguishing.
Claim 6
Dependent Claim
144 words
A semiconductor laser control apparatus repeating lighting and extinguishing of a semiconductor laser (2) at a specified ratio, continuously remaining on when a specified information is detected in a reflection light from an object to be radiated, and repeating lighting and extinguishing at said specified ratio when the following information is not detected even after the specified time has passed from said information detection timing, wherein said semiconductor laser control apparatus comprises: a third drive means for controlling the lighting of said semiconductor laser (2) with a third light quantity; a fourth drive means for controlling the lighting of said semiconductor laser (2) with a fourth light quantity larger than the third light quantity; and a control means for controlling the lighting by said third drive means in continuous lighting and changing over to said fourth drive means in repetition of lighting and extinguishing.
Claim 7
Dependent Claim
121 words
A semiconductor laser control apparatus as claimed in any one of the preceding claims, wherein said semiconductor laser control apparatus repeats switching ON and OFF of said semiconductor laser (2) at a specified ratio, continuously remains on when a specified information is detected in a reflection light from an object to be radiated and repeats lighting and extinguishing at said specified ratio when the following information is not detected even after a first time being passed from an information detection timing, and the time setting is changed from said first time to a second time shorter than said first time when said drive current value is increased by a specified percentage over the initial drive current value at the corresponding temperature.
Claim 8
Dependent Claim
43 words
A semiconductor laser control apparatus as claimed in any one of the preceding claims, wherein said memory means (24) stores a plurality of initial drive current values of said semiconductor laser (2) and corresponding temperatures of each of said initial drive current values.
Claim 9
Dependent Claim
49 words
A semiconductor laser control apparatus as claimed in any one of the preceding claims, wherein said memory means (24) stores one initial drive current value (l ref ) of said semiconductor laser (2) and a corresponding temperature (T ref ) of said initial drive current values ( l ref).
Claim 10
Dependent Claim
26 words
A semiconductor laser control apparatus as claimed in any one of the preceding claims, wherein said memory means (24) is constituted by an EEPROM or EPROM.
Claim 11
Dependent Claim
30 words
A semiconductor laser control apparatus as claimed in any one of the preceding claims, wherein said semiconductor laser (2) and said memory means (24) are provided in the same package.
Claim 12
Dependent Claim
45 words
A semiconductor laser control apparatus as claimed in any one of the preceding claims, wherein said semiconductor laser control apparatus is provided for a bar code reader device for reading the data of a bar code label and supplying the data to a point-of-sale terminal.
References Cited (Backward Citations)
No citation records indexed.
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