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US 7,743,989 B2Granted
Laser power control arrangements in electro-optical readers
AssigneeSymbol Technologies, Inc.
InventorsVladimir Gurevich, Heng (Jade) Zhang, David Tsi Shi
Life of this patent
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Abstract
Laser power control arrangements interrupt power to a laser used in electro-optical readers upon detection of operating conditions not conforming to preestablished standards, and adjust power to the laser to enhance reader performance without violating prevalent safety standards. Dual monitors are used to independently monitor the output power of the laser.
Claims11
A laser power control arrangement in an electro-optical reader for reading indicia, comprising:
- a) a laser for generating a laser beam having an output power, and wherein the laser is a laser diode;
- b) a pair of monitors for independently monitoring an operating condition of the reader, each monitor being operative for independently detecting reader malfunction when the operating condition differs from a preestablished condition, and wherein one of the monitors is a monitor photodiode and the other of the monitors is an auxiliary photodiode;
- c) an enclosure surrounding the auxiliary photodiode to prevent stray light from entering the auxiliary photodiode;
- d) a focusing lens for focusing the laser beam, and wherein the laser diode and the focusing lens are mounted adjacent each other to enable a fraction of the laser beam reflected by the focusing lens to enter a hole on the enclosure surrounding the auxiliary photodiode;
- and
- e) a controller for controlling the output power of the laser beam upon detection of the reader malfunction.
3 more elements
A laser power control method in an electro-optical reader for reading indicia, comprising the steps of:
- a) generating a laser beam having an output power with a laser, and wherein the generating step is performed by a laser diode;
- b) independently monitoring an operating condition of the reader with dual monitors, each monitor being operative for independently detecting reader malfunction when the operating condition differs from a preestablished condition, wherein the monitoring step is performed by a monitor photodiode and an auxiliary photodiode, and wherein the monitoring step further comprises reflecting a fraction of a laser beam by a focusing lens to the auxiliary photodiode through a hole on an enclosure surrounding the auxiliary photodiode for preventing stray light from entering the auxiliary photodiode;
- and
- c) controlling the output power of the laser beam upon detection of the reader malfunction.
1 more element
Dependencies are inferred from the claim text.