Bar code scanner with multi-channel light collection

• US 5,635,700 A
• Filed: 07/27/1994
• Issued: 06/03/1997
• Est. Priority Date: 07/27/1994
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Fazekas, Peter
• Primary Examiner(s): Hajec, Donald T.
• Assistant Examiner(s): LEE, MICHAEL GUNYOUNG
• Application Number:
  US08/281,413
• Time in Patent Office: 1,042 Days
• Field of Search: 235/462, 235/472, 235/463, 250/208.2, 250/208.6, 327/352, 327/514
• US Class Current: 235/462.06
• CPC Class Codes: G06K 2007/10524 Hand-held scanners
• CPC Class Codes: G06K 7/10841 Particularities of the light-sensitive elements semiconductor devices H01L

Abstract

Bar code reading in which light reflected from a scanned symbol is optically collected by a multi-channel light detector comprising an array of more than one individual light detection elements (e.g., photodetectors) each having an output capable of providing an output signal representative of light impinging thereon, amplifiers respectively coupled to each of the light detection elements, and a summing unit coupled to the outputs of each of the amplifiers for providing a signal representative of the sum of the amplified output signals of all of the light detection elements.

Claims

1. An optical reader for scanning an outgoing light beam across an information symbol comprising regions of different light reflectivity, and for collecting an incoming light beam reflecting from the symbol, the reader comprising:

a source of the outgoing light beam;

scanning optics with at least one moving optical element for tracing the outgoing light beam across the symbol;

light collection optics for collecting the incoming light beam and for directing the incoming light beam to a multi-channel light detector;

the multi-channel light detector comprising an array of more than one individual light detection elements, each having an output capable of providing an output signal representative of light impinging thereon;

the output of each detection element being coupled to a respective amplifier for amplifying the output signal of a respective detection element; and

a summing circuit having an input coupled to the amplifiers for providing a signal representative of the sum of the amplified output signals of all of the light detection elements.

4. The subject matter of claim 1, 2, or 3 wherein amplifying the output signals of the detection elements is performed by transimpedance amplification.

5. The subject matter of claim 4 wherein the detection elements comprise individually accessible photodetectors.

6. The subject matter of claim 1, 2, or 3 wherein amplifying the output signals of the detection elements is performed by equalizing amplification.

7. The subject matter of claim 6 wherein the detection elements comprise individually accessible photodetectors.

8. The subject matter of claim 1, 2, or 3 wherein scanning and light collection are performed by using a single moving optical element.

9. The subject matter of claim 8 wherein the detection elements comprise individually accessible photodetectors.

10. The subject matter of claim 1, 2, or 3 wherein light collection is performed by using a stationary optical element.

11. The subject matter of claim 10 wherein the detection elements comprise individually accessible photodetectors.

12. The subject matter of claim 1, 2, or 3 wherein field-of-view limiting optics are provided to restrict the field of view of individual detection elements.

13. The subject matter of claim 1, 2, or 3 wherein the detector is adapted so that each of the detection elements receives approximately equal amounts of the incoming light.

14. The subject matter of claim 1, 2, or 3 wherein the number of light detection elements is less than 50.

15. The subject matter of claim 1, 2, or 3 wherein the number of light detection elements is less than 16.

2. A method of optically scanning an outgoing light beam across an information symbol comprising regions of different light reflectivity, and collecting an incoming light beam reflecting from the symbol, the method comprising the steps of:

generating the outgoing light beam;

scanning the outgoing light beam across the symbol using at least one moving optical element;

collecting the incoming light beam using light collection optics and directing the incoming light beam to multi-channel light detector, the multi-channel light detector comprising an array of individual light detection elements, each capable of providing an output signal representative of light impinging thereon;

individually amplifying the output signal of each light detection element; and

summing the amplified output signals of all of the light detection elements.

3. Apparatus for optically scanning an outgoing light beam across an information symbol comprising regions of different light reflectivity, and collecting an incoming light beam reflecting from the symbol, comprising:

light source means for generating the outgoing light beam;

scanning means for scanning the outgoing light beam across the symbol using at least one moving optical element;

collecting means for collecting the incoming light beam using light collection optics and directing the incoming light beam to a multi-channel light detector;

the multi-channel light detector comprising an array of individual light detection elements, each capable of providing an output signal representative of light impinging thereon;

amplifying means for individually amplifying the output signals of each of the detection elements; and

summing means coupled to the amplifiers for providing a signal representative of the sum of the amplified output signals of all of the light detection elements.