US 7,030,353 B2Granted

Method and apparatus for controllably reducing power delivered by a laser projection display

AssigneeSymbol Technologies, Inc.

InventorsMiklos Stern, Paul Dvorkis, Narayan Nambudiri, Carl Wittenberg, Chinh Tan, Ron Goldman, Dmitriy Yavid, Frederick F. Wood

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Abstract

A method and apparatus are provided to controllably reduce power of a laser projection display (LPD) in response to detecting a variation in a viewing surface. During the operation of the LPD, a controller 142 monitors laser light being reflected from the viewing surface. Since the controller 142 “knows” the amount of power that the LPD is being instructed to deliver, it may compare the known power to the reflected laser light to determine if a foreign object may be in the path of the laser light, and therefore, affecting the magnitude of the laser light. The controller 142 responds to detecting such an event by reducing power to the lasers.

Claims16

Dependent claims

An arrangement for controlling power during projection of an image on a projection surface, comprising:

a) an energizable laser source for energizing a laser beam;
b) a controller for energizing the laser source to emit the laser beam at a reference power level during a calibration mode, and at a display power level during a display mode;
c) an image projector for sweeping the laser beam along mutually orthogonal directions across the projection surface at the reference power level to scan the projection surface during the calibration mode, and at the display power level to project the image on the projection surface during the display mode;
d) a detector for detecting a reference detected level of light reflected from the projection surface during the calibration mode, and for detecting an actual detected level of light reflected from the projection surface during the display mode;
and
e) the controller being operative for controlling the energizing of the laser source when the detected levels of the light reflected from the projection surface are different.

3 more elements

A method of controlling power during projection of an image on a projection surface, comprising the steps of:

a) energizing a laser beam from an energizable laser source;
b) energizing the laser source to emit the laser beam at a reference power level during a calibration mode, and at a display power level during a display mode;
c) sweeping the laser beam along mutually orthogonal directions across the projection surface at the reference power level to scan the projection surface during the calibration mode, and at the display power level to project the image on the projection surface during the display mode;
d) detecting a reference detected level of light reflected from the projection surface during the calibration mode, and detecting an actual detected level of light reflected from the projection surface during the display mode;
and
e) controlling the energizing of the laser source when the detected levels of the light reflected from the projection surface are different.

3 more elements

Dependencies are inferred from the claim text.