Optical reader with condensed CMOS circuitry

Details Optical reader with condensed CMOS circuitry Optical reader with condensed CMOS circuitry

1999-10-07

2001-11-06

Tremblay, Mark (Department: 2876)

Registers

Coded record sensors

Particular sensor structure

C235S470000, C235S454000

Reexamination Certificate

active

06311895

ABSTRACT:

BACKGROUND OF THE INVENTION
1) Field of the Invention
The field of the present invention relates to reading symbols such as bar codes, and more particularly to a bar code or symbol reader having integrated optical and signal processing circuitry.
2) Background
Currently available bar code readers typically have from ten to fifty integrated circuits, as well as several dozen mechanical and optical parts. The market demands, however, are for dramatically decreased cost and size of bar code readers, without sacrificing reliability or performance. A reduction in the number of parts used in bar code readers would help meet these demands.
Previous attempts to reduce, through various levels of integration, the number of parts in visible laser-based scanners have been fraught with difficulties. Visible laser diodes, which are typically made using AlGaInP material, cannot be directly integrated on a silicon substrate, which is where at least some part of the electronic or signal processing circuitry is likely to be resident. Hybrid approaches, whereby the laser diode is mounted to a thermally-conductive pad which in turn is mounted on a silicon substrate, have been demonstrated by Sony Corporation (for example, in their laser coupler used in compact disc products). In this type of construction, the performance of the electronic circuitry on the silicon substrate suffers because of the large thermal gradient across the die. Performance is also adversely affected by photo-recombination from stray laser light, causing an increase in noise levels. Moreover, reliability is also relatively poor, as with many laser-based scanner products, because of huge power density at the laser junction.
Some bar code readers use charge-coupled devices (CCDs) as a substitute for a laser diode. Integration of circuit components in these systems, however, is also difficult, primarily because CCD chips typically require highly-specialized metal-oxide semi-conductor (MOS) processes which are poorly suited for fabrication of other types of circuitry. For example, fabrication of high-transconductance field-effect transistors (FETs), generally needed in the construction of an operational amplifier, is not practical using the same MOS processes required of most CCD chips. Further, fabrication costs for this specialized process, per unit of silicon area, are considerably higher than those for conventional bipolar and CMOS processes, largely because very high silicon purity is needed to achieve reasonable charge transfer efficiency. Thus, integration of circuitry in a CCD-based bar code reader is difficult and, even if possible, would be relatively costly from a manufacturing standpoint.
The present inventors have therefore determined that it would be advantageous to provide a bar code or symbol reader having circuitry that is relatively easy to integrate, yet not prohibitively expensive to manufacture. It would further be advantageous to provide a bar code reader having a reduced number of parts, and, in addition, to provide a reduced-size bar code reader incorporating integrated optical and signal processing circuitry.
SUMMARY OF THE INVENTION
The present invention provides in one aspect an optical reader including integrated CMOS circuitry. A CMOS imaging array receives light at a multiplicity of pixel locations and converts the resulting charge to voltage locally at each pixel site. The charge is transferred upon demand directly to a common metal bus. The CMOS imaging array may be integrated with other CMOS circuitry in the optical reader.
In another aspect of the present invention, exposure time of the imaging array is controlled using a feedback loop. One or more exposure control pixels are positioned adjacent to or within the imaging array and receive light along with the imaging array. The charge of the exposure control pixel or pixels is measured against a threshold level, and the amount of time taken to reach the threshold level determines the time exposure of the pixels of the imaging array. Both the exposure control pixel or pixels and the control loop can be fabricated using the same CMOS process, and located on the same substrate as the imaging array. The exposure time may be optimally or near optimally set before the user enables the bar code reader, reducing the amount of time needed to read a symbol or code (e.g., a bar code label).
In another aspect of the invention, CMOS signal processing circuitry is employed which, in combination with the exposure control circuitry, minimizes time-to-read-over a large range of light levels, while performing spatially optimal filtering. Clocking cycles and control signals are time-adjusted in accordance with the varying output frequency of the imaging array so as to provide invariant spatial frequency response by the signal processing circuitry. These signal processing schemes may be efficiently realized in CMOS.
In another aspect of the invention, a multi-dimensional imaging array is provided having simultaneous pixel exposure with non-destructive readout of the pixel contents. The multi-dimensional imaging array may comprise a two-dimensional pattern, such as a grid or other combination of linear imaging arrays, with certain selected pixels being utilized in more than one linear imaging array. The non-destructive readout capability allows the same pixels to be read out multiple times, once for each linear imaging array of which the pixel is a member.
Further variations and modifications to the above are also described herein.


REFERENCES:
patent: 4542528 (1985-09-01), Sanner et al.
patent: 4652731 (1987-03-01), Chautemps et al.
patent: 4825291 (1989-04-01), Mimura et al.
patent: 5247161 (1993-09-01), Actis et al.
patent: 5262281 (1993-11-01), Bauer et al.
patent: 5262871 (1993-11-01), Wilder et al.
patent: 5309243 (1994-05-01), Tsai
patent: 5319182 (1994-06-01), Havens et al.
patent: 5339090 (1994-08-01), Crossland et al.
patent: 5345266 (1994-09-01), Denyer
patent: 5430282 (1995-07-01), Smith et al.
patent: 5446271 (1995-08-01), Cherry et al.
patent: 5461425 (1995-10-01), Fowler et al.
patent: 5463211 (1995-10-01), Arends et al.
patent: 5471515 (1995-11-01), Fossum et al.
patent: 5521366 (1996-05-01), Wang et al.
patent: 5627366 (1997-05-01), Katz
patent: 5635699 (1997-06-01), Cherry et al.
patent: 5665959 (1997-09-01), Fossum et al.
patent: 5739518 (1998-04-01), Wang
patent: 5770847 (1998-06-01), Olmstead
patent: 5814803 (1998-09-01), Olmstead et al.
patent: 5831674 (1998-11-01), Ju et al.
patent: 0 163 547 A2 (1985-12-01), None
patent: 0 185 450 A2 (1986-06-01), None
patent: 2 186 149A (1987-08-01), None
patent: 2 255 465A (1992-11-01), None
patent: 2 262 678A (1993-06-01), None
patent: 2 269 505 (1994-02-01), None
patent: 55-115164 (1980-09-01), None
Andoh F., et al., “A 250,000-pixel Image Sensor with FET Amplification at Each Pixel for High Speed Television Cameras”, printed in transcripts of 1990IEEE International Solid-State Circuits Conference(Digest of Technical Papers), pp. 212-213; 298.
Denyer P.B., et al., “CMOS Image Sensors for Multimedia Applications”, Proceedings of the IEEE Custom Integrated Circuits Conference (1993), pp. 11.5.1 to 11.5.4.
Fossum E., “Active Pixel Sensors Challege CCDs”,Laser Focus World(Jun. 1993), pp. 83-85.
Mendis S.K. et al., “Low-Light-Level Image Sensor with On-Chip Signal Processing”, Proceedings of the SPIE, vol. 1952, Aerospace Science and Sensing—Surveillance Sensors (1993), pp. 1-11.
Vellacott O., “CMOS in Camera”,IEEE Review(May 1994), pp. 111-114.
Examination Report from British Application No. GB 9707140.1, dated Jun. 22, 1999.
Search Report from British Application No. GB 9707140.1, dated Feb. 16, 2000.
Search and Examination Report from British Application No. GB 0001225.2, dated Feb. 16, 2000.
Search and Examination Report from British Application No. GB 0001224.5 dated Feb. 15, 2000.

Affiliated with

Also associated with

Rating

Optical reader with condensed CMOS circuitry does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Optical reader with condensed CMOS circuitry, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optical reader with condensed CMOS circuitry will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2572782