IMAGING APPARATUS AND METHOD OF DRIVING THE SAME

• US 20150009397A1
• Filed: 09/24/2014
• Published: 01/08/2015
• Est. Priority Date: 12/27/2012
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: YAMAMOTO, Takahiro, MATSUNAGA, Yoshiyuki, OTA, Takayuki
• Granted Patent: US 9,270,894 B2
• Time in Patent Office: Days
• US Class Current: 348/367
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/749 by influencing the pick-up tube voltages
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/53 Control of the integration time
• CPC Class Codes: H04N 25/589 with different integration times, e.g. short and long exposures
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/68 applied to defects

Abstract

An imaging apparatus disclosed herein includes: a solid-state imaging device in which pixels are arranged in a matrix; a mechanical shutter; and a signal processing unit, wherein the signal processing unit: resets charge stored in all the pixels by closing the mechanical shutter and applying a voltage V2 to a photoelectric conversion unit; starts first exposure by opening the mechanical shutter and applying a voltage V1 to the photoelectric conversion unit; finishes the first exposure by applying the voltage V2 to the photoelectric conversion unit with the mechanical shutter open;

reads pixel signals to obtain a first still image; resets all the pixels; starts second exposure by applying the voltage V1 to the photoelectric conversion unit with the mechanical shutter open; finishes the second exposure by applying the voltage V2 to the photoelectric conversion unit with the mechanical shutter open; reads pixel signals to obtain a second still image.

Claims

1. An imaging apparatus comprising:

a solid-state imaging device in which pixels are arranged in a matrix above a substrate, each pixel including (i) a photoelectric conversion unit which performs photoelectric conversion of incident light into signal charge and (ii) a reset unit which resets charge stored in the photoelectric conversion unit;

a mechanical shutter for causing all of the pixels to be shielded or exposed at a same time; and

a timing control unit configured to control timing for opening and closing the mechanical shutter, applying a voltage to the photoelectric conversion unit, and a reset by the reset unit,

wherein the timing control unit is configured to;

when a mode for monitoring an image is switched to a mode for capturing a still image, reset the charge stored in all of the pixels by closing the mechanical shutter and applying, to the photoelectric conversion unit, a disabling voltage for disabling movement of the charge generated by the photoelectric conversion unit; and

when a plurality of still images are to be captured sequentially;

(1) (i) start first exposure by opening the mechanical shutter and applying, to the photoelectric conversion unit, an enabling voltage for enabling movement of the charge generated by the photoelectric conversion unit, (ii) finish the first exposure by applying, to the photoelectric conversion unit, a disabling voltage for disabling movement of the charge generated by the photoelectric conversion unit, with the mechanical shutter open, (iii) obtain a first still image by reading pixel signals from the pixels, and (iv) cause the reset unit to reset the charge stored in all of the pixels; and

(2) (i) start second exposure by applying, to the photoelectric conversion unit, an enabling voltage for enabling movement of the signal charge generated by the photoelectric conversion unit, with the mechanical shutter open and (ii) finish the second exposure by applying, to the photoelectric conversion unit, a disabling voltage for disabling movement of the signal charge generated by the photoelectric conversion unit, with the mechanical shutter open, and (iii) obtain a second still image by reading pixel signals from the pixels.

2. The imaging apparatus according to claim 1,

wherein the first exposure is performed during a first exposure period, and the second exposure is performed during a second exposure period different in length from the first exposure period.

3. The imaging apparatus according to claim 1,

wherein the timing control unit is configured to obtain n still images each (i) comprising the still image and (ii) obtained through exposure in an exposure period of a different length, by performing sequential imaging n times with the mechanical shutter open, and generate m still images by combining the n still images, n being a natural number of 2 or larger, m being a natural number satisfying n≧

m.

4. The imaging apparatus according to claim 1,

wherein the enabling voltage for enabling the movement of the charge generated by the photoelectric conversion unit applied to the photoelectric conversion unit when the first exposure is performed and the enabling voltage for enabling the movement of the charge generated by the photoelectric conversion unit applied to the photoelectric conversion unit when the second exposure is performed have different values.

5. The imaging apparatus according to claim 1,

wherein the timing control unit is configured to obtain n still images each (i) comprising the still image and (ii) obtained through exposure in an exposure period during which a voltage having a different value is applied to the photoelectric conversion unit, by performing sequential imaging n times with the mechanical shutter open, and generate m still images by combining the n still images, n being a natural number of 2 or larger, m being a natural number satisfying n≧

m.

6. The imaging apparatus according to claim 4,

wherein one of the different values of the enabling voltage for enabling the movement of the charge generated by the photoelectric conversion unit and being applied to the photoelectric conversion unit when the first exposure is performed and the disabling voltage for disabling the movement of the charge generated by the photoelectric conversion unit and being applied to the photoelectric conversion unit when the second exposure is performed is a signal value indicating a black level of a video and to be output, from the pixels, as a total value of the pixel signals.

7. The imaging apparatus according to claim 6,

wherein the timing control unit is configured to perform signal processing on an image other than the black level image, based on the black level image.

8. The imaging apparatus according to claim 6,

wherein the timing control unit is configured to calculate, for each of the pixels, a value indicating a difference between data of the black level image and data of a reference image which is provided from outside, determine a pixel having a difference value exceeding a predetermined value to be a defective pixel, and correct a defect of image data in an image other than the black level image, the image data being of an image portion corresponding to the defective pixel.

9. The imaging apparatus according to claim 1, further comprising:

a focal lens; and

a memory for storing data of the pixel signals,

wherein the timing control unit is further configured to control a focal length of the focal lens, and

when the plurality of still images are to be captured sequentially,

the first still image and the second still image are obtained by changing the focal length of the focal lens, and data of the first still image and the second still image are stored in the memory.

10. A method of driving an imaging apparatus including:

a solid-state imaging device in which pixels are arranged in a matrix above a substrate, each pixel including (i) a photoelectric conversion unit which performs photoelectric conversion of incident light into signal charge and (ii) a reset unit which resets charge stored in the photoelectric conversion unit; and

a mechanical shutter for causing all of the pixels to be shielded or exposed at a same time, the method comprising;

a first reset step of resetting the charge stored in all of the pixels by closing the mechanical shutter and applying, to the photoelectric conversion unit, a disabling voltage for disabling movement of the charge generated by the photoelectric conversion unit;

a first exposure step of performing first exposure by opening the mechanical shutter and applying, to the photoelectric conversion unit, an enabling voltage for enabling movement of the charge generated by the photoelectric conversion unit, the first exposure step being performed after the first reset step;

a first reading step of (i) finishing the first exposure by applying, to the photoelectric conversion unit, a disabling voltage for disabling movement of the charge generated by the photoelectric conversion unit, and (ii) obtaining a first still image by reading pixel signals from the pixels, the first reading step being performed with the mechanical shutter open after the first exposure step;

a second reset step of causing the reset unit to reset the charge stored in all of the pixels while the disabling voltage for disabling movement of the charge generated by the photoelectric conversion unit is applied to the photoelectric conversion unit, the second reset step being performed with the mechanical shutter open after the first reading step;

a second exposure step of performing second exposure by applying, to the photoelectric conversion unit, an enabling voltage for enabling movement of the charge generated by the photoelectric conversion unit, the second exposure step being performed with the mechanical shutter open after the second reset step; and

a second reading step of (i) finishing the second exposure by applying, to the photoelectric conversion unit, a disabling voltage for disabling movement of the charge generated by the photoelectric conversion unit, and (ii) obtaining a second still image by reading pixel signals from the pixels, the second reading step being performed with the mechanical shutter open after the second exposure step.

11. The method of driving the imaging apparatus according to claim 10,

wherein, in the second exposure step, the second exposure is performed during a second exposure period different in length from a first exposure period during which the first exposure is performed.

12. The method of driving the imaging apparatus according to claim 10,

wherein in the second exposure step, the second exposure is performed by applying, to the photoelectric conversion unit, the enabling voltage different in value from the enabling voltage for enabling movement of the charge generated by the photoelectric conversion unit and applied to the photoelectric conversion unit when the first exposure is performed.

13. The method of driving the imaging apparatus according to claim 10,

wherein the first still image is obtained in the first exposure step, and the second still image is obtained in the second exposure step, by changing a focal length of a focal lens of the imaging apparatus between the first exposure step and the second exposure step, and

data of the first still image and the second still image are stored in a memory after the second reading step.