OPTICAL INFORMATION READING APPARATUS

• US 20050173538A1
• Filed: 05/24/2002
• Published: 08/11/2005
• Est. Priority Date: 05/25/2001
• Status: Active Grant

• Current Assignee: Optoelectronics Co Limited (Optoelectronics)
• Original Assignee: Optoelectronics Co Limited (Optoelectronics)
• Inventors: Tsukuda, Sachio, Nakano, Susumu
• Granted Patent: US 6,945,462 B2
• Time in Patent Office: Days
• US Class Current: 235/462.250
• 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

Abstract

An optical information reading apparatus applies light to an object to be read such as a bar code symbol, photoelectrically converts by a photodetector element a light image formed by the reflection light, and processes the obtained electric signal to output code data. Among the portions performing the signal processing, at least a data converter (13) for converting a photoelectrically converted electric signal into a digital signal, a digital signal calculation unit (17) for calculating the digital signal and generating code data indicating information of an object to be read, an input accumulation unit (20) for accumulating the code data, and a timing control unit (12) for controlling operation timings of these components are arranged on a single substrate as a multipurpose processing circuit block (10).

Claims

1. An optical information reading apparatus, comprising:

a light projection means for projecting light to an object to be read having portions with different light reflectances;

a reflector for deflecting the reflected light from the object to be read;

an imaging optical system for forming an image of deflected light by the reflector a light receiving position;

a photoelectric conversion means located at the light receiving position for photoelectrically converting the image made of the deflected light and outputting an electric signal; and

a calculation means for calculating the electric signal outputted from said photoelectric conversion means and outputting bar code binarized data indicating information of the object to be read,

said calculation means forms a multipurpose processing circuit by integrally providing, on a single substrate,

a data converter for converting the electric signal into a digital signal;

a digital signal calculation unit having a calculation processor for calculating the digital signal converted by said data converter and generating bar code binarized data, a data correction section for correcting the bar code binarized data, and a noise reduction section for reducing noises, for outputting the bar code binarized data indicating information of the object to be read;

an input accumulation unit for accumulating the bar code binarized data output from said digital signal calculation unit; and

a timing control unit for controlling operation timings of said light projection means, said photoelectric conversion means, said data converter, said digital signal calculation unit, and said input accumulation unit.

2. The optical information reading apparatus according to claim 1, wherein said multipurpose processing circuit is integrally formed on the single substrate while also including a central processing unit (CPU) for centrally controlling respective units of said calculation means.

3. The optical information reading apparatus according to claim 1, wherein said calculation unit comprises:

a first calculation processor for calculating the digital signal converted by said data converter; and

a second calculation processor for generating the bar code binarized data from data calculated by said first calculation processor.

4. The optical information reading apparatus according to claim 3, wherein:

said first calculation processor has an offset buffer to give an offset to the digital signal, and two integrators for integrating respectively said digital signal and a digital signal given the offset by the offset buffer through a shift register; and

said second calculation processor comprises a differentiator for differentiating an integrated data output from two integrators and a binarization circuit for generating the bar code binarized data from a differentiated data output from the integrators.

5. The optical information reading apparatus according to claim 4, wherein means for varying a differential time (Δ

t) in the differentiator of said second calculation processor is provided.

6. The optical information reading apparatus according to claim 3, wherein:

said first calculation processor comprises a moving average circuit for generating a moving average data from said moving digital signal; and

said second calculation processor comprises a binarization circuit for generating the bar code binarized data using the moving average data.

7. The optical information reading apparatus according to claim 6, wherein the moving average circuit of said first calculation processor comprises plural flip-flop circuits for capturing said digital signal sequentially and plural selection sections for selection necessary data out of captured data into each flip-flop circuit, and an adder for adding the selected data by the selection sections.

8. The optical information reading apparatus according to claim 4, wherein said first calculation processor is provided with a low-pass filter in front of the shift register as a noise filter for eliminating or reducing noises of the digital signal.

9. The optical information reading apparatus according to claim 4, wherein the data correction section has a function of eliminating a part being a data erase level or less of an input data into said second calculation processor out of the bar code binarized data generated by said second calculation processor.

10. The optical information reading apparatus according to claim 4, wherein said noise reduction section has a function of erasing a pals being set pals width or less from the bar code binarized data and keeping at level before change.

11. The optical information reading apparatus according to claim 4, wherein a reset section for forcibly resetting binarized data keeping a state of a high level “

H”

continuing for a predetermined length or longer out of the bar code binarized data generated in said second calculation processor is provided.

12. The optical information reading apparatus according to claim 6, wherein said moving average circuit is a weighted moving average circuit.

13. The optical information reading apparatus according to claim 12, wherein said moving average circuit has means for changing weighted amount of said weighted moving average circuit.

14. The optical information reading apparatus according to claim 12, wherein said moving average circuit has means for changing frequency response of said weighted moving average circuit.

15. The optical information reading apparatus according to claim 12, wherein said moving average circuit has means for reducing a total of high frequency components from a total of low frequency components in weight average by said weighted moving average circuit.

16. The optical information reading apparatus according to claim 6, wherein said moving average circuit is comprised of a front stage moving average circuit and a rear stage moving average circuit separately.