Dual ported memory for digital image sensor

• US 6,791,611 B2
• Filed: 05/23/2001
• Issued: 09/14/2004
• Est. Priority Date: 05/09/2000
• Status: Expired due to Term

• Current Assignee: Pixim, Inc. (Sony Group Corp.)
• Original Assignee: Pixim, Inc. (Sony Group Corp.)
• Inventors: Yang, David Xiao Dong
• Primary Examiner(s): MOE, AUNG SOE
• Application Number:
  US09/864,296
• Publication Number:
  US 20010040633A1
• Time in Patent Office: 1,210 Days
• Field of Search: 348/231.99, 348/231.9, 348/308, 348/302, 348/294, 348/221.1, 250/208.1
• US Class Current: 348/302
• 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 2201/0068 Converting from still picture data
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/741 by increasing the dynamic range of the image compared to the dynamic range of the electronic image sensors
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 7/142 Constructional details of the terminal equipment, e.g. arrangements of the camera and the display

Abstract

An image sensor architecture that accommodates the relative mismatch of bus width between the image sensor, processor, and memory is disclosed. The preferred embodiment of the invention provides a dual-ported memory structure having a relatively wide data port for receiving data from the image sensor and having a relatively narrow data port for communicating data to and from the processor. In one embodiment of the invention, the memory is organized into banks of a specific width. The banks may be accessed sequentially by the processor, such that the bus width is equivalent to the bank width, and the banks may be accessed simultaneously, such that the bus width is equivalent to the combined bank widths. A simple switching means, operating under processor control, reconfigures the memory on the fly.

Claims

1. An image sensor, comprising:

a sensor array generating digital signals representing a number of samples of an image of a scene,

data memory having a first port and a second port, the first port coupled to the sensor array by a first data bus having a first bus width to communicate with the sensor array, the second port coupled to a processor array by a second data bus having a second bus width; and

wherein the data memory receives from the first data bus a first one of the samples of the image and is updated only at certain cells therein for subsequent ones of the samples; and

the samples in the data memory is accessed by the processor from the second data bus.

2. The image sensor of claim 1 further comprises a threshold memory for determining if the certain cells in the data memory shall be update with the subsequent ones of the samples.

3. The image sensor of claim 2, wherein all of the samples of the image are sequentially generated in an exposure of the sensor array to the scene.

4. The image sensor of claim 1, wherein the sensor and data memory are integrated in an integrated circuit.

5. The image sensor of claim 4, wherein the integrated circuit also includes the processor.

6. The image sensor of claim 1, wherein the first bus width is substantially wider than the second bus width.

7. An image sensor, comprising:

a sensor array, fabricated in an integrated circuit, generating samples representing one or more images of a scene, the image sensor further comprising a first data bus having a first bus width;

a processor including a data bus having a second bus width having a second bus width that is not identical to the first bus width, wherein the controller is fabricated in the integrated circuit; and

a data memory, in communication with the sensor array and for storing values representative of the samples, including means for accommodating both the first and the second data bus widths, wherein the data memory is fabricated in the integrated circuit.

8. The image sensor of claim 7, wherein the means for accommodating comprises a dual-ported memory structure having a relatively wide data port for receiving data from the sensor array and having a relatively narrow data port for communicating data to and from the processor.

9. The image sensor of claim 7, wherein the means for accommodating comprises a bank switching mechanism for accommodating both the first and the second data bus widths.

10. The image sensor of claim 9, wherein the memory is organized into a plurality of banks B₁-B_b, each bank having a specific bank width;

wherein the banks are sequentially accessible by a bank switching mechanism, such that memory data bus width is equivalent to the specific bank width of a single bank to provide a narrower data bus for use in conjunction with the processor; and

wherein two or more of the banks are accessed simultaneously such that memory data bus width is equivalent to the combined bank widths of all of the accessed banks to provide a wider data bus for use in conjunction with the image sensor.

11. The image sensor of claim 9, wherein the bank switching mechanism comprises a switching means, operating under processor control, for reconfiguring the memory data bus on the fly.

12. The image sensor of claim 7, wherein the means for accommodating comprises a plane select scheme for accommodating both the first and the second data bus widths.

13. The image sensor of claim 7, wherein the means for accommodating comprises a shift register for accommodating both the first and the second data bus widths.

14. The image sensor of claim 7, wherein the means for accommodating comprises an external control for configuring the memory data bus width.

15. The image sensor of claim 7, wherein the processor comprises the means for accommodating and selects memory data bus width.

16. The image sensor of claim 9, wherein one or more of the memory banks are selectively assigned to two or more functional elements of the image sensor.

17. The image sensor of claim 7, wherein data is written into the data memory through the relative wide data port and simultaneously read and/or written by the processor through the relatively narrow data second port.

18. An image sensor, comprising:

a sensor array generating samples representing one or more images of a scene, the image sensor further including a data bus having a first bus speed and/or operating voltage, wherein the sensor array is fabricated in an integrated circuit;

a controller for manipulation of values in a data memory, the controller further comprising a data bus having a second bus speed and/or operating voltage that is not the same of that of the sensor array bus speed and/or operating voltage, wherein the controller is fabricated in the integrated circuit; and

a data memory, in communication with the sensor array, for storing values representative of the signals, the data memory further comprising means for accommodating both the first and the second data bus speeds and/or operating voltages, wherein the data memory is fabricated in the integrated circuit.