Method and apparatus for improving the throughput of a CCD bar code scanner/decoder

• US 5,196,684 A
• Filed: 03/25/1991
• Issued: 03/23/1993
• Est. Priority Date: 03/25/1991
• Status: Expired due to Term

• Current Assignee: Opticon Incorporated (Opto Electronics Co., Ltd.)
• Original Assignee: Opticon Incorporated (Opto Electronics Co., Ltd.)
• Inventors: Zheng, Xin, Han, Wenyu, Knight, Gerard J., Lum, Jackson
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Nguyen, Tan
• Application Number:
  US07/674,709
• Time in Patent Office: 729 Days
• Field of Search: 235/462, 235/463, 235/466, 235/470, 235/472
• US Class Current: 235/462.42
• CPC Class Codes: G06K 7/1092 sensing by means of TV-scanning

Abstract

A method for scanning and decoding the symbols of a bar code label using a CCD image sensor viewing the bar code, and coupled to a signal processor and memory, wherein initially a start of scan (SOS) first level signal is sent from the processor to the CCD image sensor, a digital data signal representative of the bar code is read from the CCD sensor, and the representative data signal read from the CCD sensor is stored in memory. When the SOS signal is at a second signal level, the stored data is validated and decoded to determine if the representative data is valid or invalid. The SOS first level signal is immediately restarted in response to an invalid bar code data signal to recollect bar code data signals from the CCD sensor viewing the bar code so that the scanning steps are repeated, or the SOS first level signal is immediately restarted to re-scan the bar code symbols immediately after the data signal is found valid. Thus, the CCD data collecting scan rate is maximized.

Claims

1. A method for scanning and decoding the symbols of a bar code label using a CCD image sensor viewing the bar code, and coupled to a signal processor with memory comprising the steps of:

(a) setting a start of scan signal (SOS) to a first signal level from the processor;

(b) while the SOS signal is at the first signal level, reading from the CCD sensor a digital data signal representative of the bar code;

(c) storing in memory the representative data signal read from the CCD sensor;

(d) validating and decoding the stored data signal when the SOS signal is at a second signal level to determine if the representative data is valid or invalid;

(e) immediately restarting the SOS first level signal whenever an invalid bar code data signal is decoded to recollect bar code data signals from the CCD sensor viewing the bar code so as to repeat step (a); and

(f) following step (d), immediately restarting the SOS first level signal so as to repeat step (a) whenever the data signal is found valid, whereby the CCD data collecting scan rate is maximized by minimizing the duration of the SOS second level signal and immediately restarting the scanning of the bar code whenever a bar code has been found to be valid or invalid.

2. The method as recited in claim 1, wherein said step of reading comprises the steps of filtering and digitizing the data signal to produce said representative signal.

3. The method as recited in claim 1, comprising the step of illuminating the bar code using lamp means in response to the SOS signal.

4. The method as recited in claim 3, wherein said lamp means comprises LED lamps.

5. The method as recited in claim 3, additionally comprising the step of examining the stored data signal of step (d) to determine if the image sensor is scanning valid or invalid bar code, successively increasing the flash time to the LED lamps in response to step (e) as the bars and spaces are scanned, resetting the flash time in response to step (f) when a data signal is found valid.

6. The method as recited in claim 5, additionally comprising an LED driver coupling the microcontroller to said LED lamps, said microcontroller increasing the flash time of said LEDs at the start of the SOS signal.

7. The method as recited in claim 1, wherein said CCD image sensor comprises a linear strip of a plurality of light sensitive pixels having an optical resolution greater than any individual bar and space of the bar code label, and a plurality of shift registers coupled to said light sensitive pixels.

8. The method as recited in claim 7, additionally comprising a timing circuit responsive to the output of the microcontroller for restarting the SOS signal, said timing circuit being coupled to the shift registers of said CCD image sensor.

9. The method as recited in claim 8, wherein said timing circuit shifts the collected bar code data from the shift registers of said CCD image sensor to said microcontroller.

10. The method as recited in claim 2, wherein said image sensor comprises lens and mirror means for focusing the bar code labels onto the pixels.

11. An apparatus for scanning and decoding the symbols of a bar code comprising:

a microcontroller having a timing circuit for generating a start of scan (SOS) first level signal and a SOS second level signal;

a CCD image sensor, coupled to said microcontroller and viewing the bar code, for scanning the bar code in response to the SOS signal;

said CCD sensor producing a digital data signal representative of the bar code;

memory means coupled to said image sensor for storing in memory the representative data signal read by said CCD signal, said microcontroller validating and decoding the stored data signal in said memory means when the SOS signal is at the second level to determine if the representative data is valid or invalid, and immediately restarting the SOS first level signal whenever an invalid bar code data signal is decoded to recollect bar code data signals from the CCD sensor viewing the bar code; and

said microcontroller immediately restarting the SOS first level signal so as to recollect bar code data signals whenever the data signal is found valid, whereby the CCD data collecting scan rate is maximized by minimizing the duration of the SOS second level signal and immediately restarting the scanning of the bar code whenever a bar code has been found to be valid or invalid.

12. The apparatus as recited in claim 11, additionally comprising a filtering and digitizing means for filtering out noise and unwanted signals from the data signal to produce said representative signal.

13. The apparatus as recited in claim 12, additionally comprising an LED driver circuit coupled to said microcontroller and having its output coupled to said LED lamps and means responsive to said SOS signal and said microcontroller for increasing the flash tie of said LEDs between the time the representative data is invalid and the data signal becomes valid.

14. The apparatus as recited in claim 13, wherein said means for increasing the flash time comprises increasing the current to the LEDs a first increment above its initial value upon reading the first invalid signal, further increasing the current to said LEDs in increments until a valid bar code is read and resetting the current to the LEDs to its initial value.

15. The apparatus as recited in claim 11, comprising lamp means for illuminating the bar code symbols in response to the SOS signal.

16. The apparatus as recited in claim 15, wherein said lamp means comprises LED lamps.

17. The apparatus as recited in claim 16, wherein said LED lamps are disposed around the periphery of said lens and mirror means to illuminate the bar code symbols.

18. The apparatus as recited in claim 11, wherein said CCD image sensor comprises a linear strip of a plurality of light sensitive pixels having an optical resolution greater than any individual bar and space of the bar code label, and means for serially shifting the data collected from said pixels.

19. The apparatus as recited in claim 18, wherein said means for serially shifting the collected data comprises a plurality of shift registers coupled to said pixels.

20. The apparatus as recited in claim 11, wherein said image sensor additionally comprises lens and mirror means for focusing the bar code labels onto the pixels.

21. An apparatus for scanning and decoding the symbols of a bar code comprising:

a microcontroller having a timing circuit for generating a start of scan (SOS) first level signal and a SOS second level signal;

an image sensor, coupled to said microcontroller and viewing the bar code, for scanning the bar code in response to the SOS signal;

said image sensor producing a digital data signal representative of the bar code;

memory means coupled to said image sensor for storing in memory the representative data signal read by said image sensor; and

said microcontroller including means validating and decoding the stored data signal in said memory means when the SOS signal is at the second level for determining whether the representative data is valid and for initiating a new SOS first level signal in response to the decoding of either one of an invalid and a valid bar code data signal.

22. The apparatus as recited in claim 21 wherein said image sensor is a charge coupled device (CCD) image sensor.

23. A method for scanning and decoding the symbols of a bar code label using an image sensor viewing the bar code, and coupled to a signal processor with memory comprising the steps of:

(a) setting a start of scan signal (SOS) to a first signal level from the processor;

(b) while the SOS signal is at the first signal level, reading from the image sensor a digital data signal representative of the bar code;

(c) storing in memory the representative data signal read from the image sensor;

(d) validating and decoding the stored data signal when the SOS signal is at a second signal level to determine whether the representative data is valid; and

(e) immediately restarting the SOS first level signal whenever an invalid bar code data signal is decoded to re-read bar code data signals from the sensor viewing the bar code so as to repeat step (a).

24. The method of claim 23 further including the step of:

immediately restarting the SOS first level signal so as to repeat step (a) whenever the data signal is found valid, whereby the data collecting scan rate is maximized by minimizing the duration of the SOS second level signal and immediately restarting the scanning of the bar code whenever a bar code has been found to be either one of valid and invalid.

25. The method of claim 24 wherein the image sensor is of the CCD type.

26. An apparatus for scanning and decoding the symbols of a bar code comprising:

a microcontroller having a timing circuit for generating a start of scan (SOS) first level signal and a SOS second level signal;

an image sensor, coupled to said microcontroller and viewing the bar code, for scanning the bar code in response to the SOS signal;

said image sensor producing a digital data signal representative of the bar code;

memory means coupled to said image sensor for storing in memory the representative data signal read by said image sensor; and

said microcontroller including means validating and decoding the stored data signal in said memory means when the SOS signal is at the second level for determining whether the representative data is valid and for controlling the duration the SOS signal is at the second level as a function of the validity of the bar code data signal.