Optical scanning head

• US 5,349,172 A
• Filed: 10/02/1992
• Issued: 09/20/1994
• Est. Priority Date: 02/27/1992
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Alex Roustaei
• Inventors: Roustaei, Alex
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US07/956,646
• Time in Patent Office: 718 Days
• Field of Search: 235/472, 235/462, 250/221
• US Class Current: 235/462.42
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10742 including a diffuser for diffusing the light from the light source to create substantially uniform illumination of the target record carrier
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning

Abstract

The optical scanning head includes at least one trio of light emitting diodes arranged so the LEDs emit light at different angles to create a fan of light. An optical module includes a light shield or "dark room" and a lens/filter assembly which provides control of the depth of focus of the scanner. The optical module is located behind the light source, and the detector, made up of a CCD array is mounted behind the optic module for detecting the light intensity in the reflected beam over a field of view across a bar code symbol. The CCD array generates an electrical signal indicative of the detected light intensity. A DC source or battery provides DC voltage to the LEDs and CCDs in response to a clocked signal which provides a gradual or sequential illumination of the LEDs and coordinates the activation of the CCDs in order to minimize power consumption during scans.

Claims

1. An optical scanning device comprising:

a printed circuit board having a front, a center and a rear portion;

an LED array having at least one trio of LEDs disposed at said front portion of said printed circuit board wherein each LED of said at least one trio is oriented to emit light at an angle different than other LEDs of said trio, said LED array projecting a reference fan of light for illuminating a bar code within a field of view to be read so that light is reflected therefrom;

a CCD detector disposed at said center of said printed circuit board for detecting a portion of reflected light from said bar code and generating an electrical signal in response thereto wherein said electrical signal is an analog representation of said bar code;

an optical assembly for receiving said reflected light and directing said reflecting light onto said CCD detector;

a conversion assembly for converting said electrical signal into a digital signal corresponding to said bar code; and

a voltage source for providing a driving voltage to said LED array, said CCD detector and said conversion assembly.

2. An optical scanning device as in claim 1 wherein said LED array comprises at least two trios of LEDS and further comprising:

a clocking device for controlling a transfer of driving voltage from said voltage source to each trio of LEDs wherein a first trio of LEDs remains on and at least one second trio of LEDs is periodically turned on and off according to a clocking signal generated by said clocking device.

3. An optical scanning device as in claim 1 further comprising:

a clocking device for controlling transfer of driving voltage from said voltage source to said at least one trio of LEDs; and

a gain controller responsive to a level of said electrical signal for controlling a level of driving voltage applied to said at least one trio of LEDs.

4. An optical scanning device as in claim 3 wherein said gain controller ramps up said level of said driving voltage when said optical scanning device is at a greater distance from said bar code.

5. An optical scanning device as in claim 1 wherein said field of view has a depth in the range of 0 to 22 inches.

6. An optical scanning device as in claim 1 wherein said LED array is disposed in a generally V-shaped arrangement.

7. An optical scanning device as in claim 1 wherein said LED array is disposed in a generally straight row across said front of said printed circuit board.

8. An optical scanning device as in claim 1 wherein said optical assembly comprises a plurality of lenses and filters for collecting and optimizing said reflected light for detection by said CCD detector.

9. An optical scanning device as in claim 8 wherein said optical assembly includes a focusing and receiving singlet lens.

10. An optical scanning device as in claim 8 wherein said optical assembly includes a pass band filter for blocking light having a wavelength outside of a predetermined range of wavelengths.

11. An optical scanning device as in claim 1 further comprising a window for filtering and manipulating said fan of light and said reflected light.

12. An optical scanning device as in claim 1 wherein said conversion assembly includes an automatic gain control for amplifying said electrical signal when a level of said electrical signal falls below a pre-determined level.

13. An optical scanning device as in claim 1 wherein said conversion assembly includes an automatic comparator control.

14. An optical scanning device as in claim 1 further comprising a light shield for blocking stray light from said optical assembly.

15. An optical scanning device as in claim 1 wherein a housing retains components of said optical scanning device, said housing having a configuration to be held in a user'"'"'s hand so that said fan of light is directed towards said bar code.

16. An optical scanning device as in claim 2 wherein said clocking device further controls a timing of scanning by said CCD detector and transfer of said electrical signal from said CCD detector to said conversion assembly.

17. An optical scanning device as in claim 1 wherein said conversion assembly includes an analog-to-digital converter and an microprocessor for manipulating said electrical signal.

18. An optical scanning device as in claim 10 wherein each LED emits visible red light within said pre-determined range of wavelengths.

19. An optical scanning device as in claim 11 further comprising a cylindrical lens disposed in front of said LED array for creating a line of light at its focal point.