Television – Camera – system and detail – Optics
Reexamination Certificate
1999-09-30
2001-03-13
Ho, Tuan (Department: 2712)
Television
Camera, system and detail
Optics
C348S234000, C358S521000
Reexamination Certificate
active
06201575
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an imaging apparatus for receiving an image and generating a video signal.
2. Description of the Prior Art
An imaging apparatus for generating a video signal in response to a received image with automatic exposure controlling is known. Such a first prior art imaging apparatus is disclosed in Japanese patent application provisional publication No. 5-56377. In the first prior art imaging apparatus, automatic exposure controlling is made in accordance with three control parameters such as an iris, a shutter speed, and a gain. A second prior art imaging apparatus discloses a gradation correction circuit for rich gradation expression in Japanese patent application provisional publication No 6-253176.
SUMMARY OF THE INVENTION
The aim of the present invention is to provide a superior imaging apparatus.
According to the present invention, a first imaging apparatus is provided, which comprises: a lens unit having an iris unit; an imaging device, the lens unit forming an image on the imaging device with brightness of the image on the imaging device controlled by the iris unit, the imaging device generating a video signal in response to the image on the imaging device; a brightness data generation portion for repeatedly generating brightness data at a regular interval in accordance with a luminance signal of the video signal; a brightness condition judging portion responsive to the brightness data generation portion for judging a condition of the brightness data; an iris control portion responsive to the brightness condition detection portion for controlling the iris unit in accordance with the brightness data; a gradation characteristic detection portion for detecting a gradation characteristic from the video signal and generating gradation control data in accordance with the detected gradation characteristic; a gradation compensation portion for compensating a gradation of the video signal in accordance with the gradation control data and outputting a gradation compensated video signal; and a control portion responsive to the brightness condition judging portion for operating either of iris control portion or the gradation characteristic detection portion with the iris control portion having a priority to the gradation characteristic detection portion.
The first imaging apparatus may further comprise an observing portion for observing the iris control portion and detecting completion of operation of the iris control portion wherein the control portion operates the gradation characteristic detection portion in response to the completion.
In the first imaging apparatus, the control portion may stop operation of the gradation characteristic detection portion in response to the brightness condition judging portion. In this case, the first imaging apparatus may further comprise a first difference detection portion, having first storing portion, for detecting a first difference between two consecutive the brightness data; a first comparing portion for comparing the first difference with a first reference; a second difference detection portion for detecting a second difference between the brightness data with target data; a second comparing portion for comparing the second difference with a second reference, wherein the control portion stops operation of the gradation characteristic detection portion in response to the brightness condition judging portion when the first difference is higher than the first reference and when the second difference is higher than the second reference.
According to the present invention, a second imaging apparatus is provided, which comprises: a lens unit having an iris unit; an imaging device, the lens unit forming an image on the imaging device with brightness of the image on the imaging device controlled by the iris unit in accordance with iris control data, the imaging device generating a video signal in response to the image on the imaging device; a brightness data generation portion for repeatedly generating brightness data at a regular interval in accordance with a luminance signal of the video signal; a first difference detection portion, having a first storing portion, for detecting a first difference between two consecutive the brightness data; a first comparing portion for comparing the first difference with a first reference; a second difference detection portion for detecting a second difference between the brightness data with target data; a second comparing portion for comparing the second difference with a second reference; an iris control portion, having a second string portion, for generating and holding the iris control data in accordance with the brightness data in response to the first and second comparing portion to reduce the second difference when the first difference is higher than the first reference and when the second difference is higher the second reference; a gradation characteristic detection portion, having a third storing portion, for detecting a gradation characteristic from the video signal and generating and holding gradation control data in accordance with the detected gradation characteristic; a gradation compensation portion for compensating a gradation of the video signal in accordance with the gradation control data and outputting a gradation compensated video signal; an operation detection portion responsive to the first and second comparing portion for detecting whether the iris control portion is operating; and a control portion for controlling the gradation characteristic detection portion to stopping detecting the gradation characteristic in response to the operation detection portion to prevent the gradation characteristic detection portion from renewing the gradation control data.
According to the present invention, a third imaging apparatus is provided, which comprises: a lens unit having an iris unit; an imaging device, the lens unit forming an image on the imaging device with brightness of the image on the imaging device controlled by the iris unit in accordance with iris control data, the imaging device generating a video signal in response to the image on the imaging device; a brightness data generation portion for repeatedly generating brightness data at a regular interval in accordance with a luminance signal of the video signal; a first difference detection portion for detecting a first difference between the brightness data and target data; a first comparing portion for comparing the first difference with a first reference; an iris control portion, having first storing portion, for generating the iris control data in accordance with the brightness data to reduce the first difference and generating a completion signal when the first difference is lower than the first reference in response to the brightness data generation portion; a gradation characteristic detection portion, having second storing portion, for detecting a gradation characteristic from the video signal and generating and holding gradation control data in accordance with the detected gradation characteristic; a gradation compensation portion for compensating a gradation of the video signal in accordance with the gradation control data and outputting a gradation compensated video signal; a second difference detection portion, having a third storing portion, for detecting a second difference between two consecutive the brightness data; a second comparing portion for comparing the second difference with a second reference; and a control portion responsive to the first and second comparing portion for operating the iris control portion when the first difference is higher than the first reference and when the second difference is higher than the second reference, controlling the iris control portion to hold the iris control data in response to the completion signal, and operating the gradation characteristic detection portion in response to the completion signal.
In the third imaging apparatus, the control portion may operate the iris control portion and stop operatin
Goldstein Israel
Ho Tuan
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