Apparatus having an image sensor that is variable in spatial resolution and bit resolution and associated method

• US 6,552,746 B1
• Filed: 06/21/1999
• Issued: 04/22/2003
• Est. Priority Date: 09/22/1998
• Status: Expired due to Term

• Current Assignee: Pixim, Inc. (Sony Group Corp.)
• Original Assignee: Pixim, Inc. (Sony Group Corp.)
• Inventors: Yang, Xiao D., Deng, Zhonghan
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US09/337,473
• Time in Patent Office: 1,401 Days
• Field of Search: 348/294, 348/295, 348/300, 348/301, 348/302, 348/303, 348/308, 257/222, 250/208.1
• US Class Current: 348/308
• CPC Class Codes: H04N 1/00281 with a telecommunication apparatus, e.g. a switched network of teleprinters for the distribution of text-based information, a selective call terminal details of transmission H04N1/00095; establishing a communication with one of a facsimile machine or another apparatus sharing a single line H04N1/32704; interfacing cordless telephone terminals with an accessory to increase the functionality of user interface H04M1/72409
• CPC Class Codes: H04N 1/00307 with a mobile telephone apparatus constructional features of portable telephone sets H04M1/0202; mobile radio systems H04W84/00
• CPC Class Codes: H04N 1/107 with manual scanning
• CPC Class Codes: H04N 1/195 the array comprising a two-dimensional array or a combination of two-dimensional arrays
• CPC Class Codes: H04N 2201/0458 Additional arrangements for improving or optimising scanning resolution or quality
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

The invention relates to a CMOS image sensor that can be embedded in portable imaging systems. This high spatial resolution and low bit resolution CMOS area image sensor not only enables portable imaging systems such as cellular fax phone, portable copy machines, barcode reader, but also it can be fabricated in standard digital CMOS processes, particularly at 0.35 micron and below. This invention also discloses several portable imaging systems using such a CMOS image sensor. This invention further discloses a CMOS image sensor that has variable spatial resolution and bit resolution. Starting as a high spatial resolution low-bit resolution image sensor, the high bit-resolution is achieved by combining information from a group of nearest-neighbor pixels into a single super-pixel via spatial oversampling. This variable CMOS image sensor can be used in a multiple function imaging device for both document and video imaging, or photography.

Claims

1. An apparatus producing image signals adaptive to a predefined application, said apparatus comprising:

an image sensor configurable to produce said image signals having a spatial resolution and an N-bit resolution in accordance with said predefined application, said image sensor having a sensor spatial resolution, said spatial resolution being upper limited by said sensor spatial resolution and N being equal to or greater than 1, wherein said image sensor includes a plurality of sensor circuits configured in a two-dimensional array, each of said sensor circuits including;

a sensor pixel producing one of said sensor signals when being exposed to said incident light; and

a first circuit causing said one of said sensor signals adjusted in accordance with one or more of parameters arranged in a two-dimensional array, wherein the size of said two-dimensional array for said parameters is substantially smaller than the size of said image sensor and each of said parameters is selectively configurable to be different from each other in accordance with said predefined application;

an optical system, in front of said image sensor, collecting and focusing incident light reflected from an object onto said image sensor; and

an output circuit, coupled to said image sensor, receiving said image signals and outputting said image signals thereof after said image signals are processed therein with respect to said predefined application.

2. The apparatus as recited in claim 1, wherein said image sensor is a Complementary Metal-Oxide Semiconductor (CMOS) sensor.

3. The apparatus as recited in claim 2, wherein said image sensor further comprises a second circuit converting said adjusted sensor signals respectively to said image signals.

4. The apparatus as recited in claim 3, wherein said second circuit comprises a plurality of comparing circuits, each of said comparing circuits comparing one of said adjusted sensor signals with a predefined threshold and outputting one of said image signals in said spatial resolution being said sensor spatial resolution and said N-bit resolution with N=1.

5. The apparatus as recited in claim 4, wherein said predefined application is for a facsimile application and said image signals is compressed according to a facsimile standard and coupled to said output circuit.

6. The apparatus as recited in claim 5, wherein said image sensor still further comprises a third circuit causing, respectively, a number of said digital signals to be combined to one of said image signals, said image signals thus being in said spatial resolution being less than said sensor spatial resolution and said N-bit resolution, wherein N>

1.

7. The apparatus as recited in claim 3, wherein said second circuit comprises a plurality of analog-to-digital converters (ADCs) producing digital signals by digitizing said adjusted sensor signals.

8. The apparatus as recited in claim 7, wherein said image sensor still further comprises a third circuit causing, respectively, a number of said digital signals to be combined to one of said image signals, said image signals thus being in said spatial resolution being less than said sensor spatial resolution and said N-bit resolution wherein N>

1.

9. The apparatus as recited in claim 1, wherein the apparatus is one of a communication device capable of voice communications and image transmission, a portable imaging device, and a document imaging device.

10. The apparatus as recited in claim 9, wherein said parameters are configured to cause a spatial resolution of the image signals from the image sensor to be less than the sensor spatial resolution such that the image signals can be efficiently transmitted.

11. The apparatus as recited in claim 10, wherein said parameters are so configured such that the image signals are generated with an M-bit resolution, and M<

N.

12. A method for producing image signals adaptive to a predefined application, the method comprising:

producing the image signals, from an image sensor, having a spatial resolution and an N-bit resolution in accordance with a predefined application, the image sensor having a sensor spatial resolution, the spatial resolution being upper limited by the sensor spatial resolution and N being equal to or greater than 1, wherein the image sensor includes a plurality of sensor circuits configured in a two-dimensional array, each of the sensor circuits including;

a sensor pixel producing one of the sensor signals when being exposed to the incident light; and

a first circuit causing the one of the sensor signals adjusted in accordance with one or more of parameters arranged in a two-dimensional array, wherein the size of the two-dimensional array for the parameters is substantially smaller than the size of the image sensor and each of the parameters is selectively configurable to be different from each other in accordance with the predefined application;

receiving the image signals in an output circuit coupled to the image sensor, and

outputting the image signals after the image signals are processed in the output circuit with respect to the predefined application.

13. The method as recited in claim 12, wherein the image sensor is a Complementary Metal-Oxide Semiconductor (CMOS) sensor.

14. The method as recited in claim 13, wherein the image sensor further comprises a second circuit converting the adjusted sensor signals respectively to the image signals.

15. The method as recited in claim 14, wherein the second circuit includes a plurality of comparing circuits, each of the comparing circuits comparing one of the adjusted sensor signals with a predefined threshold and outputting one of the image signals in the spatial resolution being the sensor spatial resolution and the N-bit resolution with N=1.

16. The method as recited in claim 15, wherein the predefined application is for a facsimile application and the image signals is compressed according to a facsimile standard and coupled to the output circuit.

17. The apparatus as recited in claim 12, wherein the image sensor still further comprises a third circuit causing, respectively, a number of the digital signals to be combined to one of the image signals, the image signals thus being in the spatial resolution being less than the sensor spatial resolution and the N-bit resolution, wherein N>

1.

18. The apparatus as recited in claim 17, wherein the second circuit comprises a plurality of analog-to-digital converters (ADCs) producing digital signals by digitizing the adjusted sensor signals.

19. The apparatus as recited in claim 18, wherein the image sensor still further comprises a third circuit causing, respectively, a number of the digital signals to be combined to one of the image signals, the image signals thus being in the spatial resolution being less than the sensor spatial resolution and the N-bit resolution wherein N>

1.