Combined range laser scanner

• US 5,420,411 A
• Filed: 07/29/1993
• Issued: 05/30/1995
• Est. Priority Date: 06/14/1991
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Mazz, Thomas, Salatto, Patrick Jr.
• Primary Examiner(s): Hajec, Donald
• Assistant Examiner(s): Frech, Karl D.
• Application Number:
  US08/098,243
• Time in Patent Office: 670 Days
• Field of Search: 235/462, 235/472, 235/467, 235/470, 235/436, 235/463, 235/466
• US Class Current: 235/462.22
• CPC Class Codes: G06K 2207/1013 Multi-focal
• CPC Class Codes: G06K 7/10574 Multiple sources
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners

Abstract

A combined range laser scanner and method for electro-optically reading indicia such as bar codes having parts of different light reflectivity which utilizes two laser diode optical illumination systems optimally focused for different working ranges. A first laser illumination system is optimized for contact operation and has a range extending to approximately two feet. The second laser illumination system is optimized for longer range scanning from approximately two to seventeen feet, and the two laser scanning systems are integrated into one combined range laser scanner. The combined range laser scanner incorporates therein logic circuitry which enables either laser illumination system as required from the particular scanning application. Depending upon which laser illumination system is selected, the laser spot speed (e.g. amplitude of the drive signal for the scanning motor) is controlled to limit the frequency of received light signals to that of standard signal processing and decoding circuits. Scanning is achieved with a common oscillating mirror element driven by a scanning motor, and the amplitude of the applied scanning motor driving signal is greater for the first laser illumination system optimized for contact or short range operation and less for the second laser illumination system for longer range scanning.

Claims

1. A combined range laser scanner assembly for electro-optically reading indicia having parts of different light reflectivity on a target located at a variable distance from the assembly, comprising;

(a) laser scanning means including a scanning mirror for causing a laser beam to be scanned over a field of view;

b) a short range laser illumination optical system for short range scanning operations;

c) a long range, longer than the short range, laser illumination optical system for long range scanning operations;

d) a collection optical system for collecting light reflected from the scanned field of view;

e) an optical detector for detecting light directed thereto by the collection optical system and for generating electrical signals corresponding to the reflected light; and

f) manually operable selection means for selectively activating the short range laser illumination system for operation at short ranges in the field of view, and for selectively activating the long range laser illumination system for operation at long ranges in the field of view.

2. A combined range laser scanner assembly as claimed in claim 1, wherein said manually operable selection means includes trigger means selectively actuated by an operator.

3. Apparatus for detecting indicia having portions of different light reflectivity comprising:

(a) a plurality of light sources for emitting a plurality of light beams and each being independently selectable by the user and focussed such that each source has a different working range at different distances from the light source;

(b) an optical scanning component disposed in the path of said beam for directing the light beam along an optical path toward a target located in the vicinity of a reference plane lying generally normal to the optical path so as to scan spatially adjacent portions of said reference plane; and

(c) sensor means having a field of view and operative for detecting at least a portion of light variable intensity reflected off the target, and for generating an electrical signal indicative of the detected light intensity.

4. Apparatus as defined in claim 3, wherein said working ranges are non-overlapping.

5. Apparatus as defined in claim 3, wherein said light sources are lasers.

6. Apparatus as defined in claim 3, further comprising selection means for selectively activating one of said plurality of light sources for operation in a predetermined working range.

7. Apparatus as defined in claim 6, wherein said selection means includes a manually operated switch actuated by an operator to select one of said predetermined working ranges of operation.

8. Apparatus as defined in claim 3, further comprising trigger means for initiating reading of the indicia each time the trigger means is actuated.

9. A system for reading indicia having portions of different light reflectivity, comprising:

scanning means for generating a light beam directed toward a target;

a manually-operable actuator, operative in a first selectable position for producing a scanning beam that enables the user to read a bar code symbol within a first working range from the scanning means, and a second selectable position for producing a second scanning beam that enables the user to read a bar code symbol within a second working range, different from said first working range, from the scanning means; and

detection means for receiving reflected light from such symbol to produce electrical means corresponding to data represented by such symbol.

10. The system according to claim 9, further comprising a housing having a handle for hand-held operation, and wherein the scanning means and detection means are disposed in the housing and the manually-operable actuator on the housing.

11. The system according to claim 10, wherein the actuator includes a multi-position trigger operatively connected to the control means to select between a first and second selectable positions.

12. The system according to claim 11, wherein the scanning means includes a movable scan element operative for sweeping the light beam across the indicia, and wherein the control means repetitively reciprocatingly moves the scan element along arcs of limited angular distance in a first operational state, and repetitively reciprocatingly moves the scan element along arcs of predetermined angular distance greater than said limited angular distances in a second operational state, said states corresponding to said selectable positions of said control means.

13. The system according to claim 9, wherein said scanning means comprises first and second distinct light sources for emitting a light beam and being focussed such that each source has a different working range at different distances from the light source.

14. A combined range laser scanner assembly for electro-optically reading indicia having parts of different light reflectivity on a target located at a variable distance from the assembly, comprising;

laser scanning means including a scanning mirror for causing a laser beam to be scanned over a field of view;

a first range laser illumination optical system including a first visible laser diode for first range scanning operations wherein a laser beam generated by said first visible laser diode is directed by said scanning mirror towards said indicia;

a second range, different than the first range, laser illumination optical system including a second visible laser diode for second range scanning operations;

a folding mirror positioned to direct a laser beam from said second visible laser diode to said scanning mirror;

a collection optical system for collecting light reflected from the scanned field of view;

an optical detector for detecting light directed thereto by the collection optical system and for generating electrical signals corresponding to the reflected light.

15. A method for detecting indicia having portions of different light reflectivity comprising:

(a) providing a plurality of light sources for emitting a plurality of light beams and each being independently selectable by the user and focussed such that each source has a different working range at different distances from the light source;

(b) directing the light beam from one of said light sources along an optical path toward a target located in the vicinity of a reference plane lying generally normal to the optical path so as to scan spatially adjacent portions of said reference plane; and

(c) detecting at least a portion of light variable intensity reflected off the target, and generating an electrical signal indicative of the detected light intensity.

16. A method as defined in claim 15, wherein said working ranges are non-overlapping.

17. A method as defined in claim 15, wherein said light sources are lasers.

18. A method as defined in claim 15, further comprising the step of selectively activating one of said plurality of light sources for operation in a predetermined working range.

19. A method as defined in claim 15, further comprising the step of initiating reading of the indicia each time a trigger switch is actuated.

20. A method of scanning a laser beam, comprising:

a. scanning a laser beam over a field of view with a scanning mirror;

b. illuminating the scanning mirror for short range scanning operations by a short range laser illumination optical system;

c. illuminating the scanning mirror for long range, longer than the short range, scanning operations by a long range laser illumination optical system;

d. collecting scanned laser radiation reflected from the scanned field of view with a collection optical system; and

e. selectively activating the short range laser illumination system for operation at short ranges in the field of view, and selectively activating the long range laser illumination system for operation at long ranges in the field of view, by manually operated switch.

21. A method of scanning a laser beam as claimed in claim 20, wherein said steps of selectively activating includes operating a trigger having first and second trigger detent positions which are selectively activated by an operator.

22. A combined method of scanning a laser beam as claimed in claim 20, wherein said step of illuminating the scanning mirror for a short range scanning includes operating in a range up to approximately two feet, and said step of illuminating the scanning mirror for a long range includes operating in a range of approximately two feet to twelve feet.

23. A system for reading indicia having portions of different light reflectivity, comprising scanning means for generating a laser beam directed toward a symbol on a target including first and second optical means for operation in first and second working ranges respectively, detection means for receiving reflected light from such symbol to produce electrical signals corresponding to data represented by such symbol;

and

selection means including a manually operated switch actuated by an operator to select one of said first and second working ranges of operation.

24. The system according to claim 23, further comprising a housing having a handle for hand-held operation, and wherein the scanning means and detection means are disposed in the housing and the switch is a manually-operable trigger on the housing.

25. The system according to claim 24, wherein the trigger includes at least first and second detent positions to select between the predetermined working ranges of operation.

26. A system according to claim 24, wherein said scanning means includes a first and a second semiconductor laser light source to produce said laser beam.

27. A method for reading indicia of different light reflectivity, comprising the steps of:

generating a light beam directed toward a target;

selectively producing by a manually-operable actuator either a first scanning beam that enables the user to read a symbol within a first working range, or a second scanning beam that enables the user to read a symbol within a second working range, different from said first working range; and

receiving reflected light from such symbol to produce electrical signals corresponding to data represented by such symbol.

28. The method according to claim 27, wherein the actuator includes a multi-position trigger to select between working ranges.

29. The method according to claim 27, further comprising the step of repetitively and reciprocatingly sweeping the light beam across the indicia along arcs of limited angular distance in a first operational state, and along arcs of predetermined angular distance greater than said limited angular distance in a second operational state, said states corresponding to said working ranges.

30. The method according to claim 29, wherein said scanning means comprises first and second distinct light sources for emitting a light beam and being focussed such that each source has a different working range at different distances from the light source.