Apparatus and method for producing a still image video signal using solid-state imaging device

• US 4,647,976 A
• Filed: 08/10/1984
• Issued: 03/03/1987
• Est. Priority Date: 08/12/1983
• Status: Expired due to Fees

• Current Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Original Assignee: Victor Company of Japan Limited (JVC Kenwood Corporation)
• Inventors: Nishiyama, Hiroshi, Nakagaki, Shintaro
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/639,347
• Time in Patent Office: 935 Days
• Field of Search: 358/909, 358/213, 358/209, 358/212, 358/335, 358/336
• US Class Current: 348/230.1
• CPC Class Codes: H04N 25/53 Control of the integration time

Abstract

A solid-state imaging device exposed to incident light ray for a predetermined period of time is driven such that photoelectric conversion signals produced therein are read out twice or more. The photoelectric conversion signals read out in sequence are added to each other such that two or more photoelectric conversion signals from each pixel are added to each other, to produce a resultant sum image signal. The photoelectric conversion signals from the solid-state imaging device may be digitally processed such that A/D converted signal resulted from a first time reading out from the solid-state imaging device is stored in a memory, and this signal is added to a subsequently A/D converted signal resulted from a second time reading out. In the case that the number of times of reading out from the solid-state imaging device is only two, the A/D converted signal resulted from the second time reading may be multiplied by a predetermined coefficient before addition. In the case that a nonlinear quantization characteristic is given to the A/D converter, nonlinear-to-linear conversion is effected before addition.

Claims

1. A still image pickup apparatus comprising:

(a) shutter means for passing a light ray from an object for only a predetermined period of time;

(b) a solid-state image pickup device responsive to said light ray from said shutter means for producing photoelectric conversion signals in respective pixels thereof;

(c) first means for reading out said photoelectric conversion signals at least twice for each exposure by said shutter means as an image signal from said solid-state image pickup device;

(d) second means for controlling said shutter means and said first means so that a reading out operation of said first means is effected when said shutter means is in a closed state;

(e) memory means for storing a first image signal resulting from a first reading out from said image pickup device;

(f) multiplying means for amplifying a second image signal resulting from a second reading out from said image pickup device so that the magnitude of said second image signal is multiplied by a variable coefficient; and

(g) third means for adding an output signal from said multiplying means to said first signal from said solid-state imaging device so that two image signals respectively resulting from first and second readings are added to each other for producing a resultant sum image signal.

2. A still image pickup apparatus as claimed in claim 1, further comprising an A/D converter responsive to said image signals from said solid-state imaging device, and a D/A converter responsive to data read out from said memory means.

3. A still image pickup apparatus as claimed in claim 2, wherein said A/D converter has a given nonlinear quantization characteristic, and said D/A converter has a given input-output charactericteristic which is reverse to said given nonlinear quantization characteristic.

4. A still image pickup apparatus as claimed in claim 3, further comprising a first nonlinear-to-linear converter responsive to said second image signal from said A/D converter for supplying said third means with a linear characteristic signal, a second nonlinear-to-linear converter responsive to said first image signal read out from said memory means for supplying said third means with a linear characterstic signal, and a linear-to-nonlinear converter responsive to an output signal from said third means for supplying said memory means with a nonlinear characteristic signal.

5. A still image pickup apparatus comprising:

(a) shutter means for passing a light ray from an object for only a predetermined period of time;

(b) a solid-state image pickup device responsive to said light ray from said shutter means for producing photoelectric conversion signals in respective pixels thereof;

(c) first means for reading out said photoelectric conversion signals at least twice for each exposure by said shutter means as an image signal from said solid-state image pickup device;

(d) second means for controlling said shutter means and said first means so that a reading out operation of said first means is effected when said shutter means is in a closed state;

(e) an A/D converter responsive to said image signal from said solid-state image pickup device;

(f) a memory responsive to a digital signal from said A/D converter for storing a first image signal resulting from a first reading out from said image pickup device;

(g) a digital multiplying means for multiplying a second image signal resulting from a second reading out from said image pickup device so that the magnitude of said second image signal is multiplied by a variable coefficient;

(h) a digital adder responsive to said first image signal read out from said memory and to said multiplied second image signal resulting from said second reading out for producing a resultant sum image signal by adding said first and said multiplied second image signals to each other;

(i) a memory control circuit for controlling reading and writing operations of said memory means, said resultant sum image signal being written into said memory means via said memory control circuit and being read out cyclically; and

(j) a D/A converter responsive to said resultant sum image signal read out from said memory means for converting the same into an analog video signal.

6. A method of producing a still image video signal using at least one solid-state imaging device, comprising the steps of:

(a) applying a light ray from an object to said solid-state imaging device for a predetermined period of time;

(b) performing a first time reading when said light ray is not being applied to said solid-state imaging device so that a first image signal including photoelectric conversion signals generated in said solid-state imaging device is read out;

(c) converting the read out first image signal into a first digital signal;

(d) storing said first digital signal into a memory;

(e) performing a second time reading when said light ray is not being applied to said solid-state imaging device so that a second image signal including photoelectric conversion signals generated in said solid-state imaging device is read out for a single light exposure for said predetermined period of time;

(f) converting said second image signal into a second digital signal;

(g) multiplying said second digital signal by a variable coefficient to obtain a multiplied second digital signal;

(h) reading out said first digital signal from said memory;

(i) adding said second digital signal to said first digital signal for obtaining a resultant sum image signal;

(j) storing said resultant sum image signal into said memory so that said first digital signal is renewed by said resultant sum image signal;

(k) reading out said resultant sum image signal from said memory cyclically; and

(l) converting said resultant sum image signal into an analog image signal.

7. A still image pickup apparatus comprising:

(a) a first means for passing a light ray from an object for a predetermined period of time;

(b) a solid-state image pickup device responsive to said light ray from said first means for producing photoelectric conversion signals in respective pixels thereof to represent a still image of the object;

(c) second means for reading out said photoelectric conversion signals representing said still image at least twice for a single light exposure for said predetermined period of time to provide at least two image signals from said solid-state image pickup device;

(d) third means for storing a first image signal resulted from a first reading out; and

(e) fourth means for adding said first image signal read out from said third means to a second image signal from said solid-state imaging device so that two image signals respectively resulting from first and second readings are added to each other for producing a resultant sum image signal.

8. A still image pickup apparatus as recited in claim 7 wherein said second means is operable for reading out said photoelectric conversion signals as residual signals of said solid-state image pickup device.

9. A still image pickup apparatus as recited in claim 8 further comprising amplifying means for amplifying said second image signal from said solid-state imaging device by a factor greater than 1.

10. A still image pickup apparatus as recited in claim 9 further comprising means for selecting the amplifying factor to correspond to a magnitude of the residual signal remaining after the first read out from said image pickup device, thereby overcoming deterioration in magnitude of residual signals in the pickup device.