Self-calibrating photoelectric control system

• US 20060091285A1
• Filed: 10/28/2004
• Published: 05/04/2006
• Est. Priority Date: 10/28/2004
• Status: Active Grant

• Current Assignee: Tri-Tronics Incorporated (Garmin Limited)
• Original Assignee: Tri-Tronics Incorporated (Garmin Limited)
• Inventors: Warner, Robert A., Hanley, David L.
• Granted Patent: US 7,071,452 B2
• Time in Patent Office: Days
• US Class Current: 250/205
• CPC Class Codes: A47F 9/04 Check-out counters, e.g. for self-service stores
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00

Abstract

A self-calibrating photoelectric control system for use in a checkstand to control the starting and stopping of a conveyer belt utilized to move products closer to a checkout clerk. The self-calibrating photoelectric control system including a light source for emitting a light beam having an intensity, a photoelectric sensor for receiving light from the light source and for generating an output signal when the received light is equal to or greater than a light-state threshold of the photoelectric sensor; and a calibration circuit for automatically calibrating the sensitivity of the photoelectric control system to partial beam breaks after occurrence of any one of a plurality of predefined events. The calibration circuit is operative for performing a calibration process which adjusts the intensity of the light beam emitted by the light source such that the intensity is slightly greater than the light-state threshold of the photoelectric sensor. By repeatedly performing the calibration process at selected times, the present invention optimizes the detection of objects that partially block the light beam, and thereby greatly enhances the system'"'"'s ability to detect translucent and low-profile products.

Claims

1. A self-calibrating photoelectric control system for use in a checkstand, said system comprising:

a light source for emitting a light beam having an intensity;

a photoelectric sensor for receiving light from said light source and for generating an output signal when said received light is equal to or greater than a light-state threshold of said photoelectric sensor; and

a calibration circuit for automatically calibrating the sensitivity of said photoelectric control system after occurrence of at least one of a plurality of predetermined events during operation of said checkstand, said calibration circuit operative for performing a calibration process which adjusts the intensity of the light beam emitted by the light source such that said intensity is greater than said light-state threshold of said photoelectric sensor.

2. The self-calibrating photoelectric control system of claim 1, wherein said intensity of said light source is adjusted so as to be only slightly greater than said light-state threshold of said photoelectric sensor.

3. The self-calibrating photoelectric control system of claim 1, wherein said intensity of said light source is adjusted so as to be only a predetermined amount greater than said light-state threshold of said photoelectric sensor.

4. The self-calibrating photoelectric control system of claim 3, wherein said predetermined amount is approximately 5% of the overall available intensity range of said light source.

5. The self-calibrating photoelectric control system of claim 1, wherein said predefined events include:

(a) initial power activation to said self-calibrating photoelectric control system; and

(b) a transition of said photoelectric sensor from a dark-state mode to a light-state mode.

6. The self-calibrating photoelectric sensor system of claim 1, further comprising an automatic shutoff element which is operative to generate an output signal when said photoelectric receiver remains in a light-state mode for a predetermined period of time.

7. The self-calibrating photoelectric control system of claim 6, wherein said predefined events include generation of an output signal by said automatic shutoff element.

8. The self-calibrating photoelectric control system of claim 1, further comprising a diagnostic circuit having a control switch which is externally accessible, said diagnostic circuit operative for initiating said calibration process upon activation of said control switch.

9. The self-calibration photoelectric control system of claim 1, wherein said calibration process comprises:

reducing the intensity of the light source such that said photoelectric sensor is in a dark-state mode;

incrementally increasing the intensity of said light source until said photoelectric sensor transitions into a light-state mode so as to determine the intensity of the light source which causes said photoelectric sensor to transition from said dark-state mode to said light-state mode; and

adjusting the intensity of said light source such that the intensity is slightly greater than the intensity of the light source which causes said photoelectric sensor to transition from said dark-state mode to said light-state mode.

10. A self-calibrating photoelectric control system for use in a checkstand to control the starting and stopping of a conveyer belt utilized to move products closer to a checkout clerk, said self-calibrating photoelectric control system comprising:

a light source for emitting a light beam having an intensity;

a photoelectric sensor for receiving light from said light source and for generating an output signal when said received light is equal to or greater than a light-state threshold of said photoelectric sensor; and

a calibration circuit for automatically calibrating the sensitivity of said photoelectric control system after occurrence of at least one of a plurality of predetermined events during operation of said checkstand, said calibration circuit operative for performing a calibration process which adjusts the intensity of the light beam emitted by the light source such that said intensity is greater than said light-state threshold of said photoelectric sensor.

11. A self-calibrating photoelectric control system for use in a checkstand according to claim 10, wherein said intensity of said light source is adjusted so as to be only slightly greater than said light-state threshold of said photoelectric sensor.

12. A self-calibrating photoelectric control system for use in a checkstand according to claim 10, wherein said intensity of said light source is adjusted so as to be only a predetermined amount greater than said light-state threshold of said photoelectric sensor.

13. A self-calibrating photoelectric control system for use in a checkstand according to claim 12, wherein said predetermined amount is approximately 5% of the overall available intensity range of said light source.

14. A self-calibrating photoelectric control system for use in a checkstand according to claim 10, wherein said predefined events include:

(a) initial power activation to said self-calibrating photoelectric control system; and

(b) a transition of said photoelectric sensor from a dark-state mode to a light-state mode.

15. A self-calibrating photoelectric control system for use in a checkstand according to claim 10, further comprising an automatic shutoff element which is operative to generate an output signal when said photoelectric receiver remains in a light-state mode for a predetermined period of time.

16. A self-calibrating photoelectric control system for use in a checkstand according to claim 15, wherein said predefined events include generation of an output signal by said automatic shutoff element.

17. A self-calibrating photoelectric control system for use in a checkstand according to claim 10, further comprising a diagnostic circuit having a control switch which is externally accessible, said diagnostic circuit operative for initiating said calibration process upon activation of said control switch.

18. A self-calibrating photoelectric control system for use in a checkstand according to claim 10, wherein said calibration process comprises:

reducing the intensity of the light source such that said photoelectric sensor is in a dark-state mode;

incrementally increasing the intensity of said light source until said photoelectric sensor transitions into a light-state mode so as to determine the intensity of the light source which causes said photoelectric sensor to transition from said dark-state mode to said light-state mode; and

adjusting the intensity of said light source such that the intensity is slightly greater than the intensity of the light source which causes said photoelectric sensor to transition from said dark-state mode to said light-state mode.

19. A method for operating a self-calibrating photoelectric control system comprising the steps of:

utilizing a light source for emitting a light beam having an intensity;

utilizing a photoelectric sensor for receiving light from said light source and for generating an output signal when said received light is equal to or greater than a light-state threshold of said photoelectric sensor; and

automatically calibrating the sensitivity of said photoelectric control system after occurrence of at least one of a plurality of predetermined events during operation of said checkstand, said calibration circuit operative for performing a calibration process which adjusts the intensity of the light beam emitted by the light source such that said intensity is greater than said light-state threshold of said photoelectric sensor.

20. The method of claim 19, wherein said intensity of said light source is adjusted so as to be only slightly greater than said light-state threshold of said photoelectric sensor.

21. The method of claim 19, wherein said intensity of said light source is adjusted so as to be only a predetermined amount greater than said light-state threshold of said photoelectric sensor.

22. The method of claim 21, wherein said predetermined amount is approximately 5% of the overall available intensity range of said light source.

23. The method of claim 19, wherein said predefined events include:

(a) initial power activation to said self-calibrating photoelectric control system; and

(b) a transition of said photoelectric sensor from a dark-state mode to a light-state mode.

24. The method of claim 19, further comprising an automatic shutoff element which is operative to generate an output signal when said photoelectric receiver remains in a light-state mode for a predetermined period of time.

25. The method of claim 24, wherein said predefined events include generation of an output signal by said automatic shutoff element.

26. The method of claim 19, wherein said calibration comprises:

reducing the intensity of the light source such that said photoelectric sensor is in a dark-state mode;

incrementally increasing the intensity of said light source until said photoelectric sensor transitions into a light-state mode so as to determine the intensity of the light source which causes said photoelectric sensor to transition from said dark-state mode to said light-state mode; and

adjusting the intensity of said light source such that the intensity is slightly greater than the intensity of the light source which causes said photoelectric sensor to transition from said dark-state mode to said light-state mode.

27. A self-calibrating photoelectric control system for use in a checkstand to control the starting and stopping of a conveyer belt utilized to move products closer to a checkout clerk, said self-calibrating photoelectric control system comprising:

a light source for emitting a light beam having an intensity;

a photoelectric sensor for receiving light from said light source and for generating an output signal when said received light is equal to or greater than a light-state threshold of said photoelectric sensor, said photosensor having a variable light-state threshold; and

a calibration circuit for automatically calibrating the sensitivity of said photoelectric control system after occurrence of at least one of a plurality of predetermined events during operation of said checkstand, said calibration circuit operative for performing a calibration process which adjusts the light-state threshold of the photosensor such that intensity of the light beam emitted by the light source is greater than said light-state threshold of said photoelectric sensor.

28. A self-calibrating photoelectric control system for use in a checkstand to control the starting and stopping of a conveyer belt utilized to move products closer to a checkout clerk, said self-calibrating photoelectric control system comprising:

a light source for emitting a light beam having an intensity;

a photoelectric sensor for receiving light from said light source and for generating an output signal when said received light is equal to or greater than a light-state threshold of said photoelectric sensor, said photosensor comprising an amplifier having a variable gain; and

a calibration circuit for automatically calibrating the sensitivity of said photoelectric control system after occurrence of at least one of a plurality of predetermined events during operation of said checkstand, said calibration circuit operative for performing a calibration process which adjusts the gain of said amplifier in said photosensor such that intensity of the light beam emitted by the light source is greater than said light-state threshold of said photoelectric sensor.