Image pickup apparatus
First Claim
1. An apparatus for picking up incident image light, comprising:
- (a) an image sensing element having an image pickup surface for receiving and sensing incident image light;
(b) diaphragm means, responsive to an aperture control signal and disposed along an optical path of the image light incident on said image sensing element, for setting an aperture size from and including a first aperture size corresponding to a fully opened diaphragm state to and including a second aperture size corresponding to a predetermined lower limit diaphragm state which is no smaller than 2% of said fully opened diaphragm state, thereby controllably changing the amount of said image light incident on said image sensing element;
(c) filter means, disposed along said optical path of said image light incident on said image sensing element and having an electrochromic layer of an electrochromic material, for changing transmissivity of said electrochromic layer in accordance with said aperture control signal selectively applied thereto, thereby changing the amount of said image light incident on said image sensing element; and
(d) exposure controlling means, selectively outputting said aperture control signal to said diaphragm means and said filter means to perform an exposure control operation with respect to said image sensing element, for only controlling said diaphragm means to set aperture size thereby performing said exposure control operation when illuminance of actual incident image light is smaller than a predetermined reference illuminance, and for controlling said diaphragm means to set and hold aperture size at said second aperture size and for controlling said filter means so as to change said transmissivity and thereby perform said exposure control operation when illuminance of actual incident image light is not less than said predetermined reference illuminance.
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Accused Products
Abstract
An image pickup apparatus such as a video camera including a pickup tube, a diaphragm mechanism and an electrochromic filter plate which are disposed along the optical path of incident image light on the pickup tube. When an illuminance of an object to be photographed is lower than a predetermined illuminance, only the diaphragm mechanism is used to suitably control an exposure of the pickup tube. However, when the illuminance of the object exceeds the predetermined illuminance level, the diaphragm mechanism is operated to keep its aperture size at a predetermined aperture size which is larger than an original minimum aperture size corresponding to a pinhole state. At the same time, the electrochromic filter plate continuously changes its light transmissivity in response to an aperture control signal, thereby controlling the exposure of the pickup tube.
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Citations
15 Claims
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1. An apparatus for picking up incident image light, comprising:
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(a) an image sensing element having an image pickup surface for receiving and sensing incident image light; (b) diaphragm means, responsive to an aperture control signal and disposed along an optical path of the image light incident on said image sensing element, for setting an aperture size from and including a first aperture size corresponding to a fully opened diaphragm state to and including a second aperture size corresponding to a predetermined lower limit diaphragm state which is no smaller than 2% of said fully opened diaphragm state, thereby controllably changing the amount of said image light incident on said image sensing element; (c) filter means, disposed along said optical path of said image light incident on said image sensing element and having an electrochromic layer of an electrochromic material, for changing transmissivity of said electrochromic layer in accordance with said aperture control signal selectively applied thereto, thereby changing the amount of said image light incident on said image sensing element; and (d) exposure controlling means, selectively outputting said aperture control signal to said diaphragm means and said filter means to perform an exposure control operation with respect to said image sensing element, for only controlling said diaphragm means to set aperture size thereby performing said exposure control operation when illuminance of actual incident image light is smaller than a predetermined reference illuminance, and for controlling said diaphragm means to set and hold aperture size at said second aperture size and for controlling said filter means so as to change said transmissivity and thereby perform said exposure control operation when illuminance of actual incident image light is not less than said predetermined reference illuminance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A video recording camera comprising:
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(a) image sensing means for receiving incident image light and for producing an electrical image signal corresponding to said incident image light; (b) object illuminance detecting means, electrically connected to said image sensing means, for generating an electrical detection signal indicating an actual amount of said incident image light; (c) light amount controlling means, electrically connected to said object illuminance detecting means and responsive to said electrical detection signal, for producing an aperture control signal which indicates a change in an aperture size so as to set said image sensing means at an optimal exposure; (d) diaphragm means, disposed along an optical path of said incident image light on said image sensing means and responsive to said aperture control signal, for changing aperture size thereof between a maximum aperture size corresponding to a fully opened diaphragm state and a predetermined minimum aperture size which is no smaller than 2% of said maximum aperture size, thereby controlling the amount of said incident image light; (e) electrochromic filter means, disposed between said diaphragm means and said image sensing means, for controlling transmissivity thereof in response to said aperture control signal, thereby controlling the amount of said incident image light; and (f) signal switching means, electrically connected between said light amount controlling means and said electrochromic filter means, for supplying said aperture control signal to only said diaphragm means when the amount of said incident image light falls in a first light amount range, and for supplying said aperture control signal to said electrochromic filter means when the amount of said incident image light falls in a second light amount range which is above said first light amount range while also causing said diaphragm means to hold said aperture size thereof at said minimum aperture size. - View Dependent Claims (12, 13, 14, 15)
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Specification