Method of controlling transmission light amount and television camera apparatus using the method

• US 20020047909A1
• Filed: 10/19/2001
• Published: 04/25/2002
• Est. Priority Date: 10/23/2000
• Status: Active Grant

• Current Assignee: Hitachi Kokusai Electric Incorporated (Hitachi, Ltd.)
• Original Assignee: Hitachi Kokusai Electric Incorporated (Hitachi, Ltd.)
• Inventors: Nakamura, Yoshifumi, Hatae, Yasuhiko, Tsukui, Akimi
• Granted Patent: US 6,674,474 B2
• Time in Patent Office: Days
• US Class Current: 348/222.1
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/75 by influencing optical camera components

Abstract

In a television camera apparatus, while a high luminance level range is detected from a picture signal which is acquired by imaging a moving photographing object by using an image pick-up element or acquired by imaging a subject almost in a static state that enters into a visual field of the image pick-up element by remotely rotating or elevating the image pick-up element, such a range which becomes a high luminance level is predicted based upon a temporal change and the like of this detected range, and such a transmission light amount control is carried out in such a manner that a light amount of imaging light of the predicted range, which is received by a light receiving plane of the image pick-up element, is extincted.

Claims

1. A television camera apparatus for photoelectrically converting incident light originated from a photographing object to acquire a picture signal, comprising:

an image pick-up unit containing a plurality of photoelectric converting elements;

a detection unit for detecting a range of a picture signal having a signal level higher than a predetermined level within said picture signals acquired from said image pick-up unit as a high luminance level range; and

a transmission light amount control unit for controlling incident light amounts of said imaging light from the photographing object with respect to the respective photoelectric converting elements every each of said photoelectric converting elements;

wherein;

said transmission amount control unit is comprised of;

a change-component detecting unit for detecting a change component between a first high luminance level range which is detected by said detection unit at a first predetermined time instant, and a second high luminance level range which is detected by said detection unit at a second predetermined time instant after said first predetermined time instant; and

a control unit of controlling the light amount of the incident light entered into said photoelectric converting elements based upon said first predetermined time instant, said second predetermined time instant, and said detected change-component.

2. A television camera apparatus according to claim 1 wherein:

said transmission light amount control unit comprises;

a liquid crystal extinction panel for adjusting the light amounts of the light entered into said photoelectric converting elements; and

a liquid crystal drive circuit for controlling transmittance of at least a portion of the incident light with respect to said liquid crystal extinction panel.

3. A television camera apparatus according to claim 2 wherein:

said liquid crystal distinction panel is constituted by a large number of liquid crystal segments.

4. A television camera apparatus according to claim 2 wherein:

said control unit for controlling the incident light amount with respect to the photoelectric converting elements includes a pattern generating unit; and

said pattern generating unit generates a control signal used to said liquid crystal extinction panel based upon the signal derived from said change-component detecting unit.

5. A television camera apparatus according to claim 1 wherein:

said transmission light amount control unit includes a high luminance level range predicting unit; and

said high luminance level range predicting unit predicts a third high luminance level range from said object based upon the detection signal derived from said change-component detecting unit at a third predetermined time instant after said second predetermined time instant, and controls the light amounts of the incident light originated from said object at said third predetermined time instant.

6. A television camera apparatus according to claim 1 wherein:

said transmission light amount control unit predicts a fourth predetermined time instant based upon said first predetermined time instant, said second predetermined time instant, and said detected change component, within such a high luminance level range higher than said predetermined level, in which a dimension of said range is larger than, or equal to a predetermined dimension; and

controls the light amounts of said incident light at said fourth predetermined time instant.

7. A television camera apparatus having a first image pick-up element and a second image pick-up element, for photoelectrically converting incident light entered from an object, comprising:

first and second image pick-up units, each of which has a plurality of photoelectric converting elements;

a detection unit for detecting a range of said picture signal having a signal level higher than a predetermined level within said picture signal acquired by said first image pick-up unit as a high luminance level range; and

a transmission light amount control unit for controlling light amounts of said incident light with respect to the respective photoelectric converting elements of said second image pick-up unit every each of said photoelectric converting elements;

wherein;

said transmission light amount control unit comprises;

a change-component detecting unit for detecting a change component between a first high luminance level range which is detected by said detection unit at a first predetermined time instant, and a second high luminance level range which is detected by said detection unit at a second predetermined time instant after said first predetermined time instant; and

a control unit of controlling the light amount of light entered into the light receiving plane of the photoelectric converting elements of said second image pick-up unit in response to said first predetermined time instant, said second predetermined time instant, and said detected change-component.

8. A television camera apparatus according to claim 7, further comprising:

a light splitting unit for splitting an imaging light entered from said object into two sets of imaging lights, said light splitting unit having a flat spectral transmittance characteristic;

wherein;

one of said imaging lights is entered into said first image pick-up unit, and the other one is entered into said second image pick-up unit.

9. A television camera apparatus according to claim 8 wherein:

in the case that light amounts of said two split imaging lights are different from each other, the split imaging light having a smaller split light amount among said two split imaging lights is entered into said first image pick-up unit, and the split imaging light having a larger split light amount is entered into said second image pick-up unit.

10. A television camera apparatus according to claim 7, further comprising:

a first optical image pick-up unit and a second optical image pick-up unit, which are used to photograph the imaging light entered from said object, are provided with said first image pick-up unit and said second image pick-up unit.

11. A transmission light amount control method used for a television camera apparatus having an image pick-up element and for acquiring a picture signal in such a manner that imaging light which is entered from an object is received by light receiving planes of a large number of photoelectric converting elements arrayed on said image pick-up element, and the imaging light received in the respective photoelectric converting elements is photoelectrically converted so as to produce said picture signal, comprising:

a step (a) in which a picture signal range having a higher signal level than a predetermined level within a picture signal imaged at a first predetermined time instant is detected as a first high luminance level range, and a picture signal range having a higher signal level than said predetermined level is detected as a second high luminance level range within a picture signal imaged at a second predetermined time instant;

a step (b) in which a change-component between said first high luminance level range and said second high luminance level range is detected; and

a step (c) in which the amount of said imaging light is controlled in response to said first predetermined time instant, said second predetermined time instant, and said change-component.

12. A transmission light amount control method according to claim 11 wherein:

said step (b) further calculates a time duration between said first predetermined time instant and said second predetermined time instant; and

said step (c) further predicts a range of a picture signal having a signal level higher than said predetermined level, which is imaged at a third predetermined time instant after said second predetermined time instant, in correspondence with said calculated time duration and said detected change-component; and

controls the transmission light amount of said transmission light amount varying unit at said third predetermined time instant in response to said predicted picture signal range.

13. A transmission amount control method according to claim 11 wherein:

said step (c) further predicts a fourth predetermined time instant after said second predetermined time instant based upon said first predetermined time instant, said second predetermined time instant, and said detected change-component, at which the range of the picture signal having the signal level higher than said predetermined level is imaged, and a dimension of said range is larger than, or equal to a predetermined dimension; and

predicts said range of the picture signal having the signal level higher than said predetermined level at said predicted fourth predetermined time instant; and

controls the transmission light amount of said transmission light amount varying unit at said third predetermined time instant in response to said predicted picture signal range.

14. A computer readable storage medium recording thereon program codes capable of being executed by a computer wherein:

said program codes perform;

a step in which imaging light entered from an object is received by light receiving planes of a large number of photoelectric converting elements arrayed on an image pick-up element, and the imaging light received by the respective photoelectric converting elements is photoelectrically converted so as to acquire picture signals;

a step in which a picture signal range having a higher signal level than a predetermined level within a picture signal imaged at a first predetermined time instant is detected as a first high luminance level range among said acquired picture signals, and also a picture signal range having a higher signal level than said predetermined level is detected as a second high luminance level range within a picture signal imaged at a second predetermined time instant;

a step in which a change-component between said first high luminance level range and said second high luminance level range is acquired; and

a step in which said transmission light amount is controlled in response to said first predetermined time instant, said second predetermined time instant, and said detected change-component in such a manner that a light amount of the imaging light received by light receiving planes of photoelectric converting elements among said large number of photoelectric converting elements.