Extended working range dataform reader with reduced power consumption

• US 5,815,200 A
• Filed: 07/25/1995
• Issued: 09/29/1998
• Est. Priority Date: 07/26/1994
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Original Assignee: Metanetics Corporation
• Inventors: Wang, Ynjiun P., Ju, Paul P.
• Primary Examiner(s): Pitts, Harold
• Assistant Examiner(s): TREMBLAY, MARK STEPHEN
• Application Number:
  US08/507,607
• Time in Patent Office: 1,162 Days
• Field of Search: 348/229, 348/230, 348/298, 235/462
• US Class Current: 348/229.1
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01J 5/08 Optical arrangements
• CPC Class Codes: G06K 2007/10524 Hand-held scanners
• CPC Class Codes: G06K 2207/1011 Aiming
• CPC Class Codes: G06K 7/10564 Light sources
• CPC Class Codes: G06K 7/10722 Photodetector array or CCD scanning
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10752 Exposure time control
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• CPC Class Codes: G06K 7/10851 Circuits for pulse shaping, amplifying, eliminating noise signals, checking the function of the sensing device basic electronic circuitry H03
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners
• CPC Class Codes: G06K 7/10891 the scanner to be worn on a finger or on a wrist
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning

Abstract

An extended working range dataform reader with reduced power consumption having a camera assembly and a circuit control board including game control circuitry and exposure control circuitry configured to set an initial gain value and an initial exposure period, respectively, resulting from a previous dataform reading session. Subsequent fields of image data are captured by the camera which are used to correct the gain and exposure relative to the initial values for gain and exposure period, thereby reducing the latency period for realizing correct values and reducing power consumption during power up. Furthermore, the gain control system and the exposure control system each utilize an open loop feedback such that successive fields of image data captured by the camera are utilized to calculate correct values, thereby reducing the latency time for realizing a correct value. Additionally, a reader module is provide for use in a dataform reader that emulates a laser module such that the dataform reader module can be readily integrated into existing laser-based dataform reading systems. Preferably, laser model emulation circuitry included in the dataform reader module emulates output of a laser scan module and a control circuit board in which the emulation circuitry is realized has an output port constructed and arranged to communicate with devices configured for use with a laser scanner.

Claims

1. A two dimensional imaging based dataform reader module configured for use in a dataform reader, the reader module comprising:

a camera assembly including an image sensor configured to detect a reflected image of an illuminated region including a dataform;

an illumination module configured to illuminate a dataform to be detected by the camera assembly;

control circuitry including a microprocessor to which the camera assembly and illumination module are operatively coupled;

gain control circuitry realized on the control circuitry and configured to set a gain value to a gain setting used during a previous dataform reading session;

exposure control circuitry realized on the control circuitry and configured to set an exposure period to a period stored in memory used during a previous dataform reading session; and

image processing circuitry embodied in code operable by a microprocessor which is operative to decode the detected dataform image;

wherein the gain value and set exposure period are each initially set to recent values at power up, afterwhich successive fields of image data are captured and the correct gain and exposure are calculated reducing the latency time for realizing correct values.

2. The dataform reader of claim 1 wherein the camera assembly comprises a board camera having an input port for receiving a power signal to power generation of a composite video signal, a gain control port, and gain adjustment circuitry connected to the gain control input port configured to bypass analog gain control circuitry.

3. The dataform reader of claim 2 further comprising a D/A converter, wherein the gain control circuitry provides a digital value to the D/A converter which supplies a voltage signal to the gain adjustment circuitry on the board camera.

4. The dataform reader of claim 2 wherein the gain control circuitry comprises digital gain control circuitry embodied in code executed by the microprocessor.

5. The dataform reader of claim 4 further comprising a look up table correlating resultant field of image data to gain values such that a correct gain value can be determined for use for a next image capture.

6. The dataform reader of claim 1 further comprising a board camera including an input port providing operating power to generate a composite video signal, an exposure control input port, and an exposure timing circuit connected to the exposure control input port configured to bypass analog exposure control circuitry.

7. The dataform reader of claim 6 further comprising a D/A converter, wherein the exposure control circuitry provides a digital value to the D/A converter which supplies voltage signals to the exposure timing circuit on the board camera.

8. The dataform reader of claim 7 wherein the exposure control circuitry comprises digital exposure control circuitry embodied in code executed by the microprocessor.

9. The dataform reader of claim 8 further comprising a look up table correlating resultant field of image data to exposure duration values such that a correct exposure duration value can be determined for use for a next image capture.

10. The dataform reader of claim 5 further comprising an exposure control input port and an exposure timing circuit connected to the exposure control input port, and configured to bypass analog exposure control circuitry, wherein the exposure control circuitry provides a digital value to the D/A converter which supplies voltage signals to the exposure timing circuit on the board camera, and the exposure control circuitry comprises digital exposure control circuitry embodied in code executed by the microprocessor, and the look up table correlates resultant field of image data to exposure duration values such that a correct exposure duration value can be determined for use for a next image capture.

11. The dataform reader of claim 3 wherein the gain control circuitry is configured in order to quickly realize a gain corrected video signal via minimal latency time.

12. The dataform reader of claim 7 wherein the exposure control circuitry is configured in order to quickly realize an exposure corrected video signal via minimal latency time.

13. The dataform reader of claim 1 wherein the control circuitry is disposed on a control and decode board on which the gain control circuitry, the exposure control circuitry, and the image processing circuitry are configured in combination with the microprocessor.

14. The dataform reader of claim 12 further comprising a data transfer link configured to interface the control board with a host computer.

15. A two dimensional imaging based dataform reader module configured for use in a dataform reader, the reader module comprising:

a camera assembly including an image sensor configured to detect a reflected image of an illuminated region including a dataform;

an illumination module configured to illuminate a dataform to be detected by the camera assembly;

a control board including a microprocessor to which the camera assembly and illumination module are operatively coupled;

gain control circuitry realized on the control board, the gain control circuitry comprising an open loop gain control system configured to set a gain value to a gain setting used during a previous dataform reading session in response to power up and incrementally adjust the gain value after evaluation of image data to achieve a gain corrected video signal within a short latency period; and

image processing circuitry operative to decode the detected dataform image.

16. The dataform reader of claim 15 wherein the camera assembly comprises a board camera having an input port for receiving a power signal to power generation of a composite video signal, a gain control input port, and gain adjustment circuitry connected to the gain input port configured to bypass analog gain control circuitry.

17. The dataform reader of claim 16 further comprising a D/A converter, wherein the gain control circuitry provides a digital value to the D/A converter which supplies a voltage signal to the gain adjustment circuitry on the board camera.

18. The dataform reader of claim 16 wherein the gain control circuitry comprises digital gain control circuitry embodied in code executed by the microprocessor.

19. The dataform reader of claim 18 further comprising a look up table correlating resultant image data to gain values such that a correct gain value can be determined for use for a next field capture.

20. A two dimensional imaging based dataform reader module configured for use in a dataform reader, the reader module comprising:

a camera assembly including an image sensor configured to detect a reflected image of an illuminated region including a dataform and a board camera including an input port providing operating power to generate a composite video signal, an exposure input port, and an exposure timing circuit connected to the exposure input port configured to bypass analog exposure control circuitry of the board camera;

an illumination module configured to illuminate a dataform to be detected by the camera assembly;

a circuit control board including a microprocessor to which the camera assemble and illumination module are coupled;

exposure control circuitry realized on the control board and configured to set an exposure period to a period stored in memory used during a previous dataform reading session; and

image processing circuitry operative to decode the detected dataform image.

21. The dataform reader of claim 20 further comprising a D/A converter and exposure control circuitry, wherein the exposure control circuitry provides a digital value to the D/A converter which supplies voltage signals to the exposure adjustment circuitry on the board camera.

22. The dataform reader of claim 20 wherein the exposure control circuitry comprises digital exposure control circuitry embodied in code executed by the microprocessor.

23. The dataform reader of claim 22 further comprising a look up table correlating resultant image data to gain values such that a correct gain value can be determined for use for a next image capture.