Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – Integrated structure
Reexamination Certificate
2000-03-17
2001-09-04
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
Integrated structure
C327S333000, C341S136000
Reexamination Certificate
active
06285250
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Inventions
The present invention relates to signal processing apparatus for use with image sensing apparatus or the like, and more particularly to signal processing apparatus for processing analog and digital signals.
2. Description of the Related Art
Various methods for processing an output signal of an image sensing device such as a CCD are known.
For example, many methods of converting an output signal of an image sensing device into a digital signal by means of a high-speed analog/digital converter (hereinafter referred to as an AD converter) and then subjecting the resultant signal to digital signal processing have been proposed. More specifically, this type method is arranged to effect AD conversion of a sensed color image signal, to execute signal processing required for an image sensing device, such as filtering, gamma conversion, matrix conversion and clipping, in a digital manner, and further to effect DA conversion by high-speed digital/analog converter (hereinafter referred to as a DA converter) for producing a video signal.
In known image sensing devices using such digital signal processing, the circuits which were used in an analog form were simply replaced with corresponding circuits in a digital form. There have been accompanying problems such as device size or production cost cannot be reduced, as a result of a larger circuit scale, an increased number of parts, and a greater consumption of current.
Also, because digital circuits and analog circuits exist in a mixed relation, interference due to mixing of digital signals with analog signals presents an obstacle in obtaining a desired SN ratio or reduction of circuit size.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the problems described above. Another object of the present invention is to prevent mixing of noise, a malfunction or circuit failure which would otherwise be caused when an analog signal processing section and a digital signal processing section are formed in a semiconductor integrated circuit in a mixed relation. To achieve those objects, the signal processing apparatus of the present invention includes a semiconductor integrated circuit in which an analog signal processing section for processing an analog signal, a digital signal processing section for transferring a signal between itself and the analog signal processing section and for processing a digital signal, and a buffer circuit disposed between the analog signal processing section and the digital signal processing section for preventing the occurrence of an abnormal signal upon power-on, are formed on a single semiconductor substrate.
With the present invention thus arranged, when an analog signal processing section and a digital signal processing section are formed in a semiconductor integrated circuit in a mixed relation, an abnormal current can be prevented from flowing upon power-on, making it possible to avoid a malfunction or failure of any circuit element. Other objects and features of the present invention will become apparent from the following description and the attached drawings.
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Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Wells Kenneth B.
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