Symbol Technologies, LLC

Mark A Weitzner

James R Giebel

Matthew D Blasczak

Gary G Schneider

Costanzo Difazio

Edward D Barkan

Vladimir P Gurevich

Peter Fazekas

Howard M Shepard

Chinh Tan

Miklos Stern

Yajun Li

Eric F Barkan

Thomas Mazz

Mark D Anderson

Vikram Bhargava

Andrew Fusco

A target is read in the presence of interference light. A photodetector generates an output signal composed of an information signal and an interference light signal. A rangefinder determines the distance of the target in a range of working distances. A controller adjusts a scan angle of a scan drive to a narrow value and adjusts an output power of a laser diode to a low power level when the target is determined to be far out in the range. The controller adjusts the scan angle to a wide value and adjusts the output power to a high power level when the target is determined to be close in the range. Signal processing circuitry processes the output signal with the information signal having a greater magnitude than that of the interference signal due to the high power level to mitigate the presence of the interference light. A power safety arrangement including dual power monitors checks the output power of the laser beam.

Apparatus for and method of monitoring output power of a laser beam during reading of targets

In an electro-optical reader, an aiming or a scanning laser has a laser chip and a monitor photodiode. Output power of a laser beam emitted by the laser is regulated by a feedback circuit for maintaining substantially constant the laser beam output power during normal operation, a disabling circuit for disabling the feedback circuit, a drive circuit for driving the chip with a drive current when the feedback circuit is disabled, and for concomitantly generating a photodiode output voltage, a current modification circuit for modifying the drive current by a predetermined current with a concomitant change in the photodiode output voltage when the feedback circuit is disabled, and a control circuit for monitoring the change in the photodiode output voltage, for determining whether the change in the photodiode output voltage is sufficient to indicate an over-power condition, and for interrupting power to the chip when the over-power condition is indicated.

Arrangement for and method of regulating laser output power in electro-optical readers

In an electro-optical reader, an aiming or a scanning laser has an internal laser chip and a monitor photodiode. A controller deenergizes the chip in a deenergized state, and energizes the chip to emit a laser beam with an output power in an energized state. A positive voltage power supply forward biases and maintains the photodiode at a substantially constant positive voltage below a threshold voltage, to support a substantially constant photodiode leakage current in both states. A signal processor supports a total current comprised of a main photodiode current indicative of the output power of the laser beam in the energized state and of the leakage current which flows opposite to the main current, and removes the leakage current from the total current to output only the main current in the energized state.

Arrangement for and method of controlling monitor photodiode leakage current in lasers in electro-optical readers

Laser power control arrangements interrupt power to a laser used in electro-optical readers upon detection of an over-power condition not conforming to preestablished regulatory standards. In one embodiment, during an operational mode, a difference between laser drive currents at two operating points is compared to a difference between laser drive currents at the same two operating points during a calibration mode. The over-power condition is recognized when the difference during the operational mode exceeds the difference during the calibration mode by a predetermined amount. In another embodiment, the laser is only energized to emit the beam at a reduced power level well below regulatory standards for staring at even if a motor drive failed.

Laser power control arrangements in electro-optical readers

A bar code scanning device, system and method that utilizes one or more vertical cavity surface emitting laser diodes for producing at least one laser beam, where the vertical cavity surface emitting laser diodes are disposed on a substrate, and wherein the produced laser beam is substantially an essential single spatial mode laser beam. The bar code scanning device, system and method of present invention also comprise a photodiode attached to the substrate and arranged to receive at least a portion of the beam of light reflected off the scanned bar code or symbol.

Scanning devices and methods using surface emitting laser diodes

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.

Crosstalk between a drive coil and a feedback coil is eliminated by a motor drive circuit operative for generating the drive coil as a square wave, and by removing the crosstalk which occurs at zero transitions of a feedback signal. The drive coil is used to oscillate a scan mirror employed in an image projection arrangement or an electro-optical reader.

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Plainview, NY, United States of America

Mark A Weitzner