Single chip camera active pixel sensor

Details Single chip camera active pixel sensor Single chip camera active pixel sensor

1998-09-29

2003-08-12

Garber, Wendy R. (Department: 2612)

Television

Camera, system and detail

Solid-state image sensor

C250S208100, C257S291000, C348S308000, C348S294000

Reexamination Certificate

active

06606122

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a single chip imaging sensor.
BACKGROUND AND SUMMARY
Imaging technology is the science of converting an image to a signal indicative thereof. Imaging systems have broad applications in many fields, including commercial, consumer, industrial, medical, defense and scientific markets.
The original image sensors included an array of photosensitive elements in series with switching elements. Each photosensitive element received an image of a portion of the scene being imaged. That portion is called a picture element or pixel. The image obtaining elements produce an electrical signal indicative of the image plus a noise component. Various techniques have been used in the art to minimize the noise, to thereby produce an output signal that closely follows the image.
Size minimization is also important. The development of the solid state charge coupled device (“CCD”) in the early 1970's led to more compact image systems. CCDs use a process of repeated lateral transfer of charge in an MOS electrode-based analog shift register. Photo-generated signal electrons are read after they are shifted into appropriate positions. However, the shifting process requires high fidelity and low loss. A specialized semiconductor fabrication process was used to obtain these characteristics.
CCDs are mostly capacitive devices and hence dissipate very little power. The major power dissipation in a CCD system is from the support electronics. One reason for this problem is because of the realities of forming a CCD system.
The specialized semiconductor fabrication process alluded to above is not generally CMOS compatible. Hence, the support circuitry for such a CCD has been formed using control electronics which were not generally CMOS compatible. The control electronics have dissipated an inordinate percentage of the power in such imaging devices. For example, CCD-based camcorder imaging systems typically operate for an hour on an 1800 mA-hr 6 V NiCad rechargeable battery, corresponding to 10.8 W of power consumption. Approximately 8 watts of this is dissipated in the imaging system. The rest is used by the tape recording system, display, and autofocus servos.
Space-based imaging systems often have similar problems. The space based systems operate at lower pixel rates, but with a lower degree of integration, and typically dissipate 20 watts or more.
The CCD has many characteristics which cause it to act like a chip-sized MOS capacitor. The large capacitance of the MOS device, for example, requires large clock swings, &Dgr;V, of the order of 5-15 V to achieve high charge transfer efficiency. The clock drive electronics dissipation is proportional to C&Dgr;V
2
f, and hence becomes large. In addition, the need for various CCD clocking voltages (e.g. 7 or more different voltage levels) leads to numerous power supplies with their attendant inefficiencies in conversion.
Signal chain electronics that perform correlated double sampling (“CDS”) for noise reduction and amplification, and especially analog to digital converters (ADC), also dissipate significant power.
The inventors also noted other inefficiencies in imaging systems. These inefficiencies included fill factor inefficiencies, fixed pattern noise, clock pick up, temporal noise and large pixel size.
Active pixel sensors, such as described in U.S. Pat. No. 5,471,515, the disclosure of which is incorporated by reference herein, use special techniques to integrate both the photodetector and the readout amplifier into the pixel area or adjacent the pixel area. This allows the signal indicative of the pixel to be read out directly. These techniques have enabled use of a logic family whose fabrication processes are compatible with CMOS. This has enabled the controlling circuitry to be made from CMOS or some other low power-dissipating logic family.
The inventors of the present invention have recognized techniques and special efficiencies that are obtained by specialized support electronics that are integrated onto the same substrate as the photosensitive element. Aspects of the present invention include integration, timing, control electronics, signal chain electronics, A/D conversion, and other important control systems integrated on the same substrate as the photosensitive element.
The disclosure also describes various improvements in such a system.


REFERENCES:
patent: 5471515 (1995-11-01), Fossum et al.
patent: 5541654 (1996-07-01), Roberts
patent: 5665959 (1997-09-01), Fossum et al.
patent: 5793322 (1998-08-01), Fossum et al.
patent: 5841126 (1998-11-01), Fossum et al.
patent: 5883830 (1999-03-01), Hirt et al.
patent: 5886659 (1999-03-01), Pain et al.
patent: 5920274 (1999-07-01), Gowda et al.
patent: 5973373 (1999-10-01), Krautschneider et al.
patent: 6011859 (2000-01-01), Kalnitsky et al.
patent: 6088822 (2000-07-01), Warren
patent: 6155488 (2000-12-01), Olmstead et al.
patent: 6400824 (2002-06-01), Mansoorian et al.
patent: 2002/0101528 (2002-08-01), Lee et al.
patent: 2002/0145669 (2002-10-01), Umeda et al.
patent: 05066625 (1993-03-01), None
Ackland, Bryan; Dickinson, Alex; “Camera on a Chip”; Feb. 8, 1996; 1996 IEEE International Solid-State Circuits Conference pp. 22-25 and 412.*
Fossum, Eric R.; “Low Power Camera-on-a-Chip Using CMOS Active Pixel Sensor Technology”; 1995; IEEE, pp. 74-77.*
Fossum, Eric R.; “CMOS Image Sensors: Electronic Camera on a Chip”; 1995; IEEE; pp. 17-25.*
Nixon, R.H., Kemeny, S.E., Staller, C.O., Fossum, E.R.; “256×256 CMOS Active Pixel Sensor Camera-on-a-Chip”; Feb. 9, 1996; 1996 IEEE International Solid-State Circuits Conference.*
Fang, Wai-Chi; Yang, Guang; Pain, Bedabrata; Sheu, bing J.; “A Low Power Smart Vision System Based on Active Pixel Sensor Integrated with Programmable Neural Processor”; 1997, IEEE; pp. 429-434.

Affiliated with

Also associated with

Rating

Single chip camera active pixel sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Single chip camera active pixel sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Single chip camera active pixel sensor will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3130962