Barcode scanner using an array of light emitting elements which are selectively activated

• US 5,545,886 A
• Filed: 07/29/1993
• Issued: 08/13/1996
• Est. Priority Date: 03/13/1990
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Metlitsky, Boris, Katz, Joseph, Marom, Emanuel, Gousgounis, Dean
• Primary Examiner(s): NGUYEN, TAN
• Application Number:
  US08/098,991
• Time in Patent Office: 1,111 Days
• Field of Search: 235/471, 235/462, 235/472, 235/470, 358/475, 250/553, 250/552, 250/568
• US Class Current: 235/462.42
• CPC Class Codes: G06K 7/10574 Multiple sources
• CPC Class Codes: G06K 7/10673 Parallel lines
• CPC Class Codes: G06K 7/10702 Particularities of propagating elements, e.g. lenses, mirrors G06K7/10831 takes precedence
• CPC Class Codes: G06K 7/14 using light without selection of wavelength, e.g. sensing reflected white light G06K7/10831 - G06K7/1097 take precedence
• CPC Class Codes: G06K 7/1417 2D bar codes
• CPC Class Codes: G06K 7/1473 error correction

Abstract

A bar code scanner employs an electronic means for causing the light beam to scan a bar code symbol, rather than using a mechanical device to generate the scan. A linear array of light sources, activated one at a time in a regular sequence, may be imaged upon the bar code symbol to simulate a scanned beam. Instead of a single linear array of light sources, a multiple-line array may be employed, producing multiple scan lines. The multiple scan lines may be activated in sequence, or activated simultaneously (time-division or frequency-division multiplexed. The multiple scan lines can provide signal enhancement, noise reduction or fault correction if directed to the same bar code pattern. Multiple scan lines may be generated using a single light source and a beam splitter, with mechanical scanning, as well as by the sequentially-activated light sources. Multiple simultaneous scan lines may be employed to generate a raster scan at lower mechanical scan frequency. In another embodiment, a tunable laser may be employed to provide a scan without moving parts; a laser beam from the tunable laser is reflected from a diffraction grating that produces an angular deviation dependent upon the wavelength of the laser output. As the frequency of the tunable laser is varied in some selected pattern, the laser beam will scan accordingly.

Claims

1. A bar code scanner, comprising:

a) a scanning light beam generator for simultaneously producing a plurality of scan lines at different frequencies to impinge upon a bar code symbol or other symbol which encodes data using variations in light reflectivity, wherein said light beam generator includes an array of light emitting elements which are activated in a predetermined sequential order;

b) a sensor, responsive to the scan lines reflected from the bar code symbol, for detecting light reflected from said bar code symbol and for producing an electrical signal representing data represented by said symbol; and

c) a decoder which decodes the electrical signal produced by the sensor to generate a decoded signal indicative of the information contained in the symbol, wherein said decoder includes means for demultiplexing said electrical signal to recover separate signals for each scan line.

2. A bar code scanner, comprising;

a) a scanning light beam generator for simultaneously producing a plurality of scan lines to impinge upon a bar code symbol or other symbol which encodes data using variations in light reflectivity, wherein said light beam generator includes an array of light emitting elements, which are activated in a predetermined sequential order and wherein said scan lines are modulated at different frequencies;

b) a sensor, responsive to the scan lines reflected from the bar code symbol, for detecting light reflected from said bar code symbol and for producing an electrical signal representing data represented by said symbol, wherein said electrical signal is filtered to separate responses to said plurality of scan lines; and

c) a decoder which decodes the electrical signal produced by the sensor to generate a decoded signal indicative of the information contained in the symbol.

3. A bar code scanner according to claim 2 wherein said elements are in at least one linear array and each linear array is activated in sequence beginning at one end and continuing in a regular pattern to the other end.

4. A bar code scanner according to claim 2 wherein said multiple scan lines are repeated in a raster scan pattern.

5. A bar code scanner according to claim 2 wherein said multiple scan lines are generated by different light sources.

6. A method of reading a symbol comprising the steps of:

(a) simultaneously directing a plurality of light beam scan lines modulated at different frequencies emitted from an array of light emitting elements to a target field where said symbol may be present;

(b) detecting light reflected from said field from the plurality of scan lines;

(c) producing an electrical signal corresponding to the reflected light from said plurality of scan lines; and

(d) filtering the electrical signal to separate responses corresponding to respective ones of the plurality of scan lines.

7. A method of reading a symbol according to claim 6 further including the step of decoding the filtered electrical signal to generate a decoded signal indicative of the information contained in the symbol.

8. A scanner comprising:

a) a scanning light beam generator for simultaneously producing a plurality of scan lines modulated at different frequencies to impinge upon a symbol which encodes data using variations in light reflectivity, wherein said light beam generator includes an array of laser diodes which are activated in a predetermined seguential order;

(b) a sensor for receiving said light from said symbol and for producing an electrical signal representing data represented by said signal; and

(c) a filter for filtering the electrical signal to separate responses to said plurality of scan lines.

9. A bar code scanner according to claim 8 further comprising a decoder which decodes said electrical signal produced by said sensor to generate a decoded signal indicative of the information contained in said symbol.

10. A bar code scanner according to claim 8 wherein said predetermined sequential order comprises turning on the first light emitting element in a row of said array, then turning off said first light emitting element and turning on the immediately adjacent light emitting element in the same row and continuing to turn off and turn on the adjacent light emitting element until the entire row has been traversed.

11. A bar code scanner, comprising:

a) a scanning light beam generator for simultaneously producing a plurality of scan lines at different frequencies to impinge upon a bar code symbol or other symbol which encodes data using variations in light reflectivity, wherein said light beam generator includes a plurality of light emitting elements;

b) a mirror positioned between the scanning light beam generator and the bar code symbol for reflecting the scan lines toward the bar code symbol; and

c) a sensor, responsive to the scan lines reflected from the bar code symbol, for detecting light reflected from said bar code symbol and for producing an electrical signal representing data represented by said symbol.

12. The bar code scanner as claimed in claim 11 wherein the light emitting elements are light emitting diodes.

13. The bar code scanner as claimed in claim 11 wherein the light emitting elements are laser diodes.

14. The bar code scanner as claimed in claim 11 further including filter means for demodulating the electrical signal to recover separate signals for each scan line.