Optical scanning head

• US 5,532,467 A
• Filed: 09/16/1994
• Issued: 07/02/1996
• Est. Priority Date: 02/27/1992
• Status: Expired due to Fees

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Scanquest Corporation
• Inventors: Roustaei, Alex
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US08/307,911
• Time in Patent Office: 655 Days
• Field of Search: 235/472, 235/455
• 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 scanner for reading and decoding information encoded in a bar code comprising alternating lines of light and dark, said optical scanner comprising:

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

an array of light emitting diodes comprising at least one combination of light emitting diodes disposed at said front of said printed circuit board in an arrangement wherein each light emitting diode of said at least one combination emits light at a non-zero angle with respect to a centerline bisecting said printed circuit board from said front to said rear so that a fan of light is projected from said array toward a reference plane within a field of view containing said bar code so that light is reflected therefrom;

an optical assembly disposed at a center of said printed circuit board for receiving, concentrating and directing reflected light toward said rear of said board;

a CCD array disposed at said rear of said printed circuit board for detecting a portion of said reflected light directed thereon by said optical assembly and generating an electrical signal in response thereto wherein said electrical signal is an analog representation of said bar code;

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

a voltage source for providing a driving voltage to said array of light emitting diodes, said CCD array and said conversion assembly.

2. An optical scanner as in claim 1 wherein said array of light emitting diodes comprises at least two combinations of light emitting diodes and further comprising:

a clocking device for controlling a transfer of driving voltage from said voltage source to each combination of light emitting diodes wherein a first said combination remains on when said optical scanner is activated and at least one second said combination is periodically turned on and off according to a clocking signal generated by said clocking device.

3. An optical scanner as in claim 1 further comprising:

a clocking device for controlling transfer of driving voltage from said voltage source to said at least one combination of light emitting diodes; 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 combination of light emitting diodes.

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

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

6. An optical scanner as in claim 1 wherein said array of light emitting diode is disposed in a generally V-shaped arrangement.

7. An optical scanner as in claim 1 wherein said array of light emitting diodes is disposed in a generally straight row across said front of said printed circuit board.

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

9. An optical scanner as in claim 1 wherein each light emitting diode of said array emits visible red light.

10. An optical scanner as in claim 9 wherein said visible red light has a wavelength of 660 nanometers.

11. An optical scanner as in claim 1 wherein each light emitting diode of said array emits infrared light.

12. An optical scanner as in claim 8 wherein said optical assembly includes a bandpass filter for blocking light having a wavelength outside of a range around a pre-determined wavelength at which said array of light emitting diodes emits.

13. An optical scanner as in claim 1 further comprising a window disposed at said front of said printed circuit board for filtering said fan of light and said reflected light.

14. An optical scanner as in claim 1 wherein said conversion assembly includes an automatic gain control for controlling gain in response to a detected intensity level of said reflected light.

15. An optical scanner as in claim 2 wherein said clocking device further controls a timing of scanning of said CCD array and a transfer of said electrical signal to said conversion assembly.

16. An optical scanner as in claim 1 wherein said optical assembly further comprises a light shield to block out stray light.

17. An optical scanner as in claim 1 wherein said optical assembly is slidable in a direction running from said front to said rear of said printed circuit board to permit variation in a depth of field of said optical scanner.

18. An optical scanner as in claim 1 wherein said CCD array has a density of elements selected according to a density of said alternating lines of said bar code.

19. An optical scanner as in claim 1 wherein said fan of light has an intensity distribution which is denser at a center of said fan.

20. An optical scanner as in claim 1 further comprising a housing for hand-held operation.

21. An optical scanner as in claim 20 further comprising a trigger for activating and de-activating said optical scanner.

22. An optical scanner as in claim 1 further comprising means for indicating a drain of said voltage source.

23. An optical scanner as in claim 1 further comprising a cylindrical lens disposed in front of said array of light emitting diodes for creating a line of light at a focal point of said cylindrical lens.

24. An optical scanner for scanning a bar code symbol having a first width, said optical scanner comprising:

at least one printed circuit board having a front, a center, a rear and a longitudinal centerline bisecting said at least one printed circuit board into a first side and a second side, said front having a second width smaller than said first width;

a plurality of LEDs disposed on said front of said at least one printed circuit board for emitting an incident beam of light for illuminating said bar code symbol, a first portion of said plurality of LEDs being disposed on said first side and a second portion of said plurality of LEDs being disposed on said second side, each of said first portion and said second portion of LEDs being oriented to emit light at a non-zero angle with respect to said centerline so that a first half of said incident beam emitted by said first portion of LEDs intersects a second half of said incident beam emitted by said second portion of LEDs wherein said incident beam of light has a beam width which increases at increasing distances from said front of said at least one printed circuit board;

an optical focusing means disposed at said center of said at least one printed circuit board for focusing light;

a detector means disposed at said rear of said at least one printed circuit board for detecting light focussed by said optical focussing means and generating an electrical signal representative of said bar code symbol therefrom;

a signal processing means in electrical communication with said detector means for converting said electrical signal into an output comprising data descriptive of said bar code symbol; and

a voltage source for providing voltage to said plurality of LEDs, said detector means and said signal processing means.

25. An optical scanner for scanning a bar code symbol having a first width, said optical scanner comprising:

a housing for hand-held operation having a second width at a front end at which an incident beam of light for illuminating said bar code symbol exits said housing, said second width being smaller than said first width, said housing having a handle portion having dimensions for being held in a user'"'"'s hand;

at least one printed circuit board retained within said housing and having a front corresponding to said front end of said housing, a center, a rear and a longitudinal centerline bisecting said printed circuit board into a first side and a second side;

a plurality of LEDs disposed on said front of said at least one printed circuit board, a first portion of said plurality of LEDs being disposed on said first side and a second portion of said plurality of LEDs being disposed on said second side, said first portion of LEDs and said second portion of LEDs being positioned on either side of said centerline so that said plurality of LEDs emits a diverging incident beam of light beyond said front end;

an optical focusing means disposed at said center of said at least one printed circuit board for focusing light;

a detector means disposed at said rear of said at least one printed circuit board for detecting light focused by said optical focusing means and generating an electrical signal representative of said bar code symbol therefrom;

a signal processing means for converting said electrical signal into an output comprising data representative of said bar code symbol; and

a voltage source for providing voltage to said plurality of LEDs, said detector means and said signal processing means;

wherein said optical scanner is held at a distance from said bar code symbol and said diverging incident beam of light has a width at least as wide as said first width at a point at which said diverging incident beam of light contacts said bar code symbol.

26. An optical scanner as in claim 25 further comprising a trigger disposed on said housing adjacent said handle portion for activating and deactivating said optical scanner.