Image sensing apparatus having exposure level and dynamic range control circuit
First Claim
1. An exposure control circuit for an image input device that produces an electronic image input signal of a subject using a solid-state imaging element, comprising:
- light-amount adjusting means for adjusting an amount of an incident light received from said subject;
solid-state imaging element means for enabling a reading of an image signal included in said incident light in a nondestructive manner, to produce the electronic image input signal of the subject and to control a read timing;
accumulating means for accumulating a plurality of the image signals, read in said nondestructive manner by said solid-state imaging element means;
number-of-additions control means for controlling a number of additions to be performed by said accumulating means;
condition setting means for setting said light-amount adjusting means, said solid-state imaging element means, and said number-of-additions control means so as to selectively set an amount of incident light, an amount of exposure time, and a number of additions to be performed by said accumulating means according to one of a luminance of said subject and the conditions set by said condition setting means;
converting means for converting said accumulated plurality of image signal accumulated in said accumulating means into linear output signals; and
an image processing circuit for processing the linear output signals of said converting means, thereby to provide an image signal.
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Accused Products
Abstract
In the exposure control circuit of an image input device according to the present invention, the rays of light from the subject pass through a diaphragm adjusting the amount of light and undergoes photoelectric conversion at a CCD imaging element. The image signal read from the CCD imaging element is accumulated more than once at an accumulating circuit. The luminance of the subject is detected at a luminance detector. Based on the detected luminance, a condition setting circuit sets the amount of incident light, exposure time, and the number of additions to suitable values. With those suitable settings, the amount of light through the diaphragm, the exposure time of the CCD imaging element, and the number of accumulations by the accumulating circuit are controlled so as to enable the subject to be photographed under the best condition.
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Citations
16 Claims
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1. An exposure control circuit for an image input device that produces an electronic image input signal of a subject using a solid-state imaging element, comprising:
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light-amount adjusting means for adjusting an amount of an incident light received from said subject; solid-state imaging element means for enabling a reading of an image signal included in said incident light in a nondestructive manner, to produce the electronic image input signal of the subject and to control a read timing; accumulating means for accumulating a plurality of the image signals, read in said nondestructive manner by said solid-state imaging element means; number-of-additions control means for controlling a number of additions to be performed by said accumulating means; condition setting means for setting said light-amount adjusting means, said solid-state imaging element means, and said number-of-additions control means so as to selectively set an amount of incident light, an amount of exposure time, and a number of additions to be performed by said accumulating means according to one of a luminance of said subject and the conditions set by said condition setting means; converting means for converting said accumulated plurality of image signal accumulated in said accumulating means into linear output signals; and an image processing circuit for processing the linear output signals of said converting means, thereby to provide an image signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An exposure control circuit for an image input device that produces an electronic image input signal of a subject, said exposure control circuit comprising:
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light-amount adjusting means for adjusting an amount of incident light received from said subject; solid-state imaging element means for enabling a reading of an image included in said incident light, for generating the electronic image input signal of the subject and for controlling an exposure time; accumulating means for accumulating a plurality of image signals read by said solid-state imaging element means; number-of-addition control means for controlling a number of additions to be performed by said accumulating means; luminance detecting means for detecting the luminance of the subject and for providing a detected luminance output signal, said luminance detecting means comprising a nondestructive solid-state image reading element and a peak-value detecting means for detecting a maximum value of a plurality of charges accumulated by said accumulating means; and condition setting means for setting said light-amount adjusting means, said solid state imaging element means, and said number-of-addition control means so as to selectively adjust said amount of incident light, said amount of exposure time, and said number of additions to be performed by said accumulating means, based on the luminance of the subject detected by said luminance detecting means. - View Dependent Claims (8, 9, 10)
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11. An exposure control circuit for an image input device that produces an electronic image input signal of a subject, said exposure control circuit comprising:
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light-amount adjusting means for adjusting an amount of incident light received from said subject; solid-state imaging element means for enabling a reading of an image included in said incident light, for generating the electronic image input signal of the subject and for controlling an exposure time; accumulating means for accumulating a plurality of image signals read by said solid-state imaging element means; number-of-addition control means for controlling a number of additions to be performed by said accumulating means; subtracting means for detecting a fixed-pattern of inherent noise of said solid-state imaging element means for a photograph of the subject, said subtracting means subtracting a value of said fixed-pattern of inherent noise from one of an output signal from said solid-state imaging element means or an output signal from said accumulating means; storing means for storing said fixed-pattern of inherent noise of said solid-state imaging element means; and condition setting means for setting said light-amount adjusting means, said solid state imaging element means, and said number-of-addition control means so as to selectively adjust said amount of incident light, said amount of exposure time, and said number of additions to be performed by said accumulating means, based on the luminance of the subject. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification