Television – Camera with built-in test signal generator – test pattern – or...
Patent
1993-08-02
1995-04-11
Groody, James J.
Television
Camera with built-in test signal generator, test pattern, or...
348187, 348265, 348537, 348222, H04N 1700, H04N 5335
Patent
active
054063299
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a solid state image pickup apparatus comprising a solid state image pickup device which receives an image of an object to be picked up and generates an image signal representing the image of the object in synchronism with a driving pulse, a driving means for generating the driving pulse to be supplied to the solid state image pickup device, a sampling means for generating a sampled image signal by sampling the image signal read from the solid state image pickup deice by means of a sampling pulse synchronized with said driving pulse, a means for generating the sampling pulse to be supplied to the sampling means, an analog-to-digital converting means for converting the sampled image signal to a digital image signal by means of a sampling pulse for analog-to-digital conversion, and a means for generating the sampling pulse for analog-to-digital conversion to be supplied to the analog-to-digital converting means, and the present invention also relates to a solid state image pickup device used in the above mentioned solid state image pickup apparatus.
DESCRIPTION OF THE BACKGROUND ART
Various television cameras using a solid state image pickup device as an device have been proposed, and television cameras using a charge-coupled device (CCD) as a solid sate image pickup device have been widely used. In a CCD camera, a signal read out of the CCD is sampled by a sampling circuit, for example a correlative double sampling circuit, is passed through analog signal processing circuits which perform a filtering process to remove clock noise, a gain control, a non-linear processing, and the like, and then is sampled and converted into a digital image signal by means of an analog-to-digital converter to take out a television image signal. The analog-to-digital converter samples and holds a digital image signal by means of a sample and hold circuit and converts the thus held signal to a digital signal. In the case where a flash type analog-to-digital converter is used and as the analog-to-digital converter, an input analog image signal is directly converted into a digital image signal, and the analog-to-digital conversion is performed in synchronism with the sampling pulse. In order to distinguish the sampling pulse used in the analog-to-digital converter from the sampling pulse used in the correlative double sampling circuit, in this specification the former sampling pulse is called a sampling pulse for analog-to-digital conversion.
A known solid state image pickup apparatus whose block diagram is shown in FIG. 1 reads a CCD 1 with a driving pulse from a CCD driving gate array 3 for generating a CCD driving signal in response to a reference clock signal generated by a reference oscillator (OSC) 2, samples the signal read from the CCD 1 by means of a correlative double sampling circuit 4, passes the signal through an analog signal processing circuit 6 performing a gain control, nonlinear processing and the like, after passing it through a low-pass filter 5 to remove clock noise, and then makes an analog-to-digital conversion in an analog-to-digital converting circuit 7 by means of a sampling pulse for analog-to-digital conversion to obtain a digital television image signal.
The correlative double sampling circuit 4 has three sample and hold circuits 4a, 4b and 4c driven by three sampling pulses whose phases are different from each other and which are generated by the CCD driving gate array 3, and derives by means of a differential amplifier 4d a difference in level between two sampled values taken by sampling the signal read from the CCD 1, namely, a sampled value (black sample, as shown in FIG. 2A) taken by sampling the signal from the CCD 1 at a black level sampling point B in a zero-signal period and a sampled value (white sample as shown in FIG. 2A) taken by sampling the signal from the CCD at a white level sampling point W in a signal period. Since the correlative double sampling circuit is set just behind the CCD 1 and processes the signal which has not pas
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Kashimura Naoki
Kawamura Kazuhiro
Groody James J.
Hsia Sherrie
Ikegami Tsushinki Co. Ltd.
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