Digital image sensor and noise cancellation operation method

• US 20080074512A1
• Filed: 09/27/2006
• Published: 03/27/2008
• Est. Priority Date: 09/27/2006
• Status: Abandoned Application

• Current Assignee: Lite-On Semiconductor Corporation (Diodes Incorporated)
• Original Assignee: Lite-On Semiconductor Corporation (Diodes Incorporated)
• Inventors: Tsou, Ming-Chien, Sung, Yu-Chen
• Application Number:
  US11/527,462
• Publication Number:
  US 20080074512A1
• Time in Patent Office: Days
• US Class Current: 348/241
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/772 comprising A/D, V/T, V/F, I/T or I/F converters

Abstract

A digital image sensor and noise cancellation operation method reduces noise of an analog sensor circuit inside a digital image sensor and simplifies the complex design of an analog/digital signal of the prior art. The present invention provides a novel digital image sensor for converting at least one analog noise signal to at least one digital noise signal outputted via an analog/digital converter. The digital noise signal is written to a memory and compared with the original digital image signal for generating at least one image signal clearly. The digital image sensor of the present invention is replaced with an analog correlated double sampling circuit for canceling out noise.

Claims

1. A digital image sensor, comprising:

a photo sensor circuit for generating at least one sample-and-hold analog signal;

an analog-to-digital signal conversion circuit for converting the sample-and-hold analog signal to at least one digital signal;

a first memory unit connected with the analog-to-digital signal conversion circuit for storing at least one digital reset noise signal of the digital signal;

a second memory unit connected with the analog-to-digital signal conversion circuit for storing at least one digital image signal of the digital signal; and

a digital logic correcting circuit receiving the digital reset noise signal and the digital image signal for executing a signal correcting process and outputting at least one image sensor signal.

2. The digital image sensor of claim 1, further comprising a digital signal process unit for digitizing the image sensor signal.

3. The digital image sensor of claim 1, wherein the first memory unit or the second memory unit is a section of a memory.

4. The digital image sensor of claim 3, wherein the memory is a register or a non-volatile memory.

5. The digital image sensor of claim 1, further comprising a first read switch connected to the first memory unit for controlling the digital reset signal timing.

6. The digital image sensor of claim 1, further comprising a second read switch connected to the second memory unit for controlling the digital image signal timing.

7. The digital image sensor of claim 1, wherein the digital logic correcting circuit is a subtractor.

8. A operation method for KTC noise cancellation of a digital image sensor, comprising:

sampling at least one sample-and-hold signal;

converting the sample-and-hold signal to at least one digital signal;

separating the digital signals into at least one digital reset noise signal and at least one image signal;

storing separately the digital reset noise signal and the image signal on a first memory unit and a second memory unit;

using a digital logic correcting circuit to compare the digital reset noise signal and the digital image signal; and

outputting at least one image sensor signal after comparing the digital reset noise signal and the digital image signal.

9. The operation method of claim 8, wherein the first memory unit or the second memory unit is a section of a memory.

10. The operation method of claim 8, wherein the memory is a register or a non-volatile memory.

11. The operation method of claim 8, wherein the digital logic correcting circuit is a subtractor.

12. The operation method of claim 8, wherein the image sensor signal is generated from the digital logic correcting circuit for canceling the digital reset noise signals.