Claims
- 1. A device for reading bar code symbols or the like, comprising:
- a light source for generating a continuous light beam directed toward a symbol to be read during a symbol reading operation to produce a scanned spot, wherein said spot is scanned across said symbol;
- a detector receiving reflected light from said scanned spot on such symbol to produce electrical signals corresponding to a representation of the symbols during said reading operation;
- a control circuit for modifying said continuous light beam during said reading operation in response to said electrical signals from said detector by varying said light source between a narrow-scan low power mode of operation and a wide-scan higher power mode of operation, wherein said control circuit is responsive to whether said electrical signals represent a pattern of a bar code symbol to vary said light source between said narrow-scan low power mode and said wide-scan higher power mode.
- 2. A device according to claim 1 wherein said control circuit includes a timer to cause said device to operate in said high power mode for only a predetermined time duration.
- 3. A device according to claim 1 wherein said control circuit includes a timer to switch to said low power mode at a selected time after switching to said high power mode.
- 4. A device according to claim 1 wherein said light beam is modified by varying the spot size produced where the light beam impinges upon said symbol.
- 5. A bar code reader comprising:
- a light beam scanner generating a light beam directed toward a symbol to be read and moving said light beam along said symbol during a symbol reading operation to provide a scan;
- a light detector receiving reflected light from said symbol and generating electrical signals responsive to said reflected light during said reading operation;
- said light beam scanner being controlled during said reading operation in response to said electrical signals to provide a first narrow-scan mode of operation for finding said symbol and a second wide-scan mode of operation for interpreting the contents of said symbol;
- wherein said light beam scanner includes a semiconductor laser light source to produce said light beam.
- 6. A device according to claim 5 wherein said light beam scanner produces a light beam of intensity selectable in response to said electrical signals.
- 7. A device according to claim 6 wherein said light beam scanner includes a semiconductor laser light source, and is controlled by varying the drive current of said light source.
- 8. A device according to claim 7 wherein said drive current is varied to provide a low power mode until said electrical signal indicates that a bar code symbol is present, then to provide a high power mode.
- 9. A method of scanning bar code symbols or the like, comprising the steps of:
- directing a light beam toward a bar code symbol to read, and scanning said light beam on a path along said symbol during a symbol reading operation;
- detecting light reflected from the symbol and generating an electrical signal in response to said reflected light;
- determining whether or not said electrical signal exhibits characteristics of a bar code signal, and
- modifying said light beam in response to a content of said electrical signal during said symbol reading operation, wherein said step of modifying includes changing the shape of said path from a first narrow-scan shape to a second different wide-scan shape, and wherein said step of modifying is in response to said step of determining.
- 10. A method according to claim 9 wherein said step of modifying includes controlling the intensity of said light beam and the length of said path in response to the character of said electrical signal.
- 11. A method according to claim 9 wherein said step of determining includes counting the rate of transitions of said reflected light from one state to another state.
- 12. A method according to claim 9 wherein said step of determining includes detecting the ratio to one state to another state of said reflected light.
- 13. A method according to claim 9 wherein said step of determining includes comparing a said electrical signal for one scan of said symbol by said light beam to that for another scan of said symbol by said light beam.
- 14. A method according to claim 9 wherein said light source is a semiconductor laser diode and said step of modifying includes changing the drive current to said laser diode from a low power mode to a high power mode.
- 15. A method according to claim 14 wherein said changing is in response to said electrical signal exhibiting the characteristic of a scanned bar code symbol.
Parent Case Info
This application is a continuation of application Ser. No. 506,674 filed Apr. 9, 1990, now abandoned, which is a continuation of application Ser. No. 260,692, filed Oct. 21, 1988, now U.S. Pat. No. 4,933,538 issued Jun. 12, 1990.
US Referenced Citations (34)
Continuations (2)
|
Number |
Date |
Country |
Parent |
506674 |
Apr 1990 |
|
Parent |
260692 |
Oct 1988 |
|