Optical-scanning system employing laser and laser safety control

• US 5,665,942 A
• Filed: 08/16/1995
• Issued: 09/09/1997
• Est. Priority Date: 11/05/1993
• Status: Expired due to Term

• Current Assignee: Steelcase Incorporated
• Original Assignee: Microfield Graphics, Inc. (Steelcase Incorporated)
• Inventors: Williams, Guy L., Wilson, Scott E., Jenness, Timothy A.
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US08/516,434
• Time in Patent Office: 755 Days
• Field of Search: 128/18, 128/19, 128/20, 359/17, 359/285, 359/299, 359/315, 359/345, 372/8, 372/9, 372/12, 372/18, 372/24, 345/179, 345/182
• US Class Current: 178/19.01
• CPC Class Codes: B41J 2/442 using lasers
• CPC Class Codes: B41J 2/471 using dot sequential main scanning by means of a light deflector, e.g. a rotating polygonal mirror
• CPC Class Codes: G02B 26/125 Details of the optical system between the polygonal mirror and the image plane G02B26/123, G02B26/127 take precedence; F-Theta lenses G02B13/0005
• CPC Class Codes: G02B 26/127 Adaptive control of the scanning light beam, e.g. using the feedback from one or more detectors G02B27/0031 takes precedence

Abstract

An optical-scanning system including a laser, a multi-faceted, rotational scanning mirror, and system-monitoring laser safety structure operatively and informationally connected respectively to the laser and to the mirror and the drive motor for the mirror for altering the effective power output of the laser in response to current operational status of the system as determined by current operational status of the rotating mirror. The safety structure enforces on the laser a duty cycle of operation which is less than 100-percent, causes the laser to power down to a low "sleep" operating level at times other than during a normal scanning sweep, de-powers the laser entirely if either the drive motor for the mirror is not enabled or the rotational speed of the mirror is below full normal operating speed, and also positively de-powers the laser when a user shuts down the system.

Claims

1. In an optical-scanning system

a light-beam source in the form of a laser,

a power-operated, rotational scanning instrumentality positioned adjacent said source and operable, with rotation, to scan a beam from the source in successive scanning sweeps through a scanning zone,

system-monitoring laser safety structure operatively and informationally connected, respectively, to said source and to said instrumentality, operable, in response to the currently understood operational status of said instrumentality, to alter accordingly the effective power output of said source, and

duty-cycle substructure which is responsive to information regarding instrumentality angular position to create a power-flow duty cycle for said source which is less than 100-percent, whereby the source is powered at one selected operating level during the time of a scanning sweep, and powered at another, lower, selected sleep level between successive scanning sweeps.

2. The system of claim 1, wherein said structure further includes sleep-level-observing substructure operable, under circumstances with the source intended to be powered at sleep level, to stop the flow of power to the source on observing an operating power level above sleep level.

3. The system of claims 1 or 2, wherein said structure contains rotational-speed-monitoring and drive-power-enable substructure which allows the supply of power to said source only under circumstances of both drive-power enablement for, and confirmed attainment of selected, normal, rotational operating speed by, said instrumentality.

4. The system of claims 1 or 2, wherein said structure includes system-on-following substructure operable, on a command being given to remove drive power from said instrumentality, to stop the flow of power to said source.

5. The system of claim 3, wherein said structure includes system-on-following substructure operable, on a command being given to remove drive power from said instrumentality, to stop the flow of power to said source.