Television – Camera – system and detail – Solid-state image sensor
Reexamination Certificate
1997-10-16
2001-04-24
Ho, Tuan (Department: 2612)
Television
Camera, system and detail
Solid-state image sensor
C348S297000
Reexamination Certificate
active
06222585
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a semiconductor device having a pixel protective circuit and, more particularly, to the structure of an address scanning circuit for an array of pixels provided in a semiconductor device.
(b) Description of the Related Art
In a semiconductor device having an X-Y address scanning circuit for a two-dimensional array of pixels, a horizontal shift register and a vertical shift register provided in the semiconductor device feed pixel selecting pulses in sequence. The shift registers consecutively turn on the horizontal switches and vertical switches to read pixel data one by one. The horizontal and vertical shift registers receive clock signals and data signals through respective signal lines for controlling the X-Y address to generate the pixel selecting pulses, as described in Patent Publication No. JP-A-8(1996)-105794.
In a conventional semiconductor device having an X-Y address scanning circuit, if a failure such as a signal stop occurs in a clock signal or data signal, the X-Y scanning circuit may stop the operation thereof or involve a malfunction, which sometime selects a single pixel for a long time. Such a long time selection of a single pixel imposes an overload on the selected pixel to deteriorate or destroy the selected pixel in the semiconductor device. Among the semiconductor devices having an X-Y scanning circuit, an infrared ray sensor is exemplified hereinafter wherein a bolometer is provided for each of pixels for photo-electric conversion.
If a disconnection occurs, for example, in a signal transmission line for controlling the X-Y address of the clock signal or data signal to thereby stop the X-Y scanning circuit or cause a malfunction in the horizontal shift register or vertical shift register, the bolometer of the selected pixel is subjected to overtime current flowing therethrough to be overheated by self heating, which causes characteristic deterioration or burnout destruction of the bolometer. Such a situation is similar in any semiconductor device having an address scanning circuit for an array of pixels.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a semiconductor device having an address scanning circuit for an array of pixels, which is capable of preventing the characteristic deterioration or burnout destruction of selected pixels.
The present invention provides a semiconductor device comprising a plurality of pixels each having a specified function, a shift register for receiving a data signal and a clock signal to shift the data signal therein based on the clock signal, the shift register having a plurality of stage outputs each for supplying a pixel selecting signal, a switching section for selecting at least one of the pixels at a time based on the pixel selecting signal, at least one signal line for transferring data from or to a selected pixel selected by the switching section, and a monitor section for outputting a disable signal by detecting a case of overtime selection of one of the pixels, the disable signal disabling the switching section for selection of any of the pixels.
In accordance with the present invention, since an overtime selection of a single pixel can be avoided by disabling the switching section for selection of pixels, the characteristic deterioration of burnout destruction of the selected pixel does not take place.
The above and other objects, features and advantages of the present invention will be more apparent from the following description, referring to the accompanying drawings.
REFERENCES:
patent: 5387933 (1995-02-01), Fouilloy et al.
patent: 5844605 (1998-12-01), Gorelik
patent: 5867215 (1999-02-01), Kaplan
patent: 5-158430 (1993-06-01), None
patent: 5-323893 (1993-12-01), None
patent: 7-319418 (1995-12-01), None
patent: 8-105794 (1996-04-01), None
“Dictionary of Physics, Revised Ed.”(published by Baifukan—publication date Oct. 30, 1992).
Foley & Lardner
Ho Tuan
NEC Corporation
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