Electric lamp and discharge devices: consumable electrodes – With economizer
Reexamination Certificate
1996-04-10
2001-06-19
Ho, Tuan (Department: 2612)
Electric lamp and discharge devices: consumable electrodes
With economizer
C348S311000
Reexamination Certificate
active
06248133
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a solid state imaging device having a reading gate mechanism which can realize miniaturization of it and to a method of driving the device.
2. Related Art of the Invention
Conventionally there are a isolating region for isolating the photoelectric converting parts of pixels and a reading region for reading electric charge stored in the each photoelectric converting parts. These regions are invalid region about sensitivity and saturation characteristics and the area of the photoelectric converting parts is large enough, there is little effect on account of the invalid region and it is not significant for the practical use.
However the miniaturization of CCD is required recently and the above invalid region can not be disregarded and then deterioration of sensitivity and saturation characteristics become large.
That is miniaturization of a solid state imaging device produces insufficient sensitivity due to reduction of the light receiving area, and reduction of the incident light range due to reduction of the pixel area. At present, a CCD solid state imaging device of the ⅓-inch class has the incident light range of about 8 bits. When objects of about 5,000 Lx and 5 Lx exist in the same screen, for example, one of the objects must be sacrificed. This produces a problem peculiar to a photographic process in so-called backlight or excessive forwardlight in the following manner: If the aperture of the lens or the electronic shutter is set to 5,000 Lx, the sensitivity is insufficient for the object of 5 Lx so that an image of the object cannot be taken. By contrast, if the aperture of the lens or the electronic shutter is set to 5 Lx, the object of 5,000 Lx causes a signal charge of an amount exceeding the signal charge amount range of the solid state imaging device to be generated, thereby causing overexposure.
Meanwhile for expanding the incident light range, such method that in one field period two kinds of image signals which have different exposure period to each other are read out to outside is known.
However the prior structure has problem due to miniaturization of an element:
That is in order to improve the sensitivity and saturation characteristics it is suggested to make the photoelectric part large but there are isolation part and reading part separately to each other and the enlarging of the photoelectric part is restricted.
SUMMARY OF THE INVENTION
According to the invention, a read gate which is specially disposed in the prior art is eliminated, and a pixel isolating portion exhibits also the reading function, thereby improving the actual opening area so that the sensitivity is enhanced. In order to completely conduct the reading from a pixel portion to a transfer portion, a potential gradient (incline) is formed in a photoelectric converting portion or a read gate. And signal charge amounts obtained in two kinds of exposure periods are independently read/transferred for each line to vertical charge transferring means (Vertical Charge Coupled Device), thereby eliminating an external field memory.
A solid state imaging device of the present invention is characterized in that a unit pixel comprises:
at least one photoelectric converting portion which is disposed in order to convert an electromagnetic wave or an X-ray entering said unit pixel into a signal charge and which contains a first impurity; and charge transferring means adjacent to said photoelectric converting portion in an X-direction and for transferring said signal charge in a Y-direction, and
at boundaries of photoelectric converting portions adjacent to each other in the Y-direction in the unit pixels which are arranged in a one-dimensional direction of Y-direction or in two-dimensional directions of X- and Y-directions, there is first means which serves as isolating said photoelectric converting portions from each other, and also as reading a signal charge from said photoelectric converting portion into said charge transferring means.
A driving method for a solid state imaging device of the present invention is characterized in that a unit pixel comprises:
at least one photoelectric converting portion which is disposed in order to convert an electromagnetic wave or an X-ray entering said unit pixel into a signal charge and which contains a first impurity; and charge transferring means adjacent to said photoelectric converting portion in an X-direction and for transferring said signal charge in a Y-direction, and
at boundaries of photoelectric converting portions adjacent to each other in the Y-direction in the unit pixels which are arranged in a one-dimensional direction of Y-direction or in two-dimensional directions of X- and Y-directions, there is first means which serves as isolating said photoelectric converting portions from each other, and also as reading a signal charge from said photoelectric converting portion into said charge transferring means, and
when said device is driven, the isolating function and the reading function are realized alternately in the Y-direction, by the first means at a specific field and further at a next field the isolating function and the reading function are exchanged.
A solid state imaging device of the present invention is characterized in that a unit pixel comprises:
at least one photoelectric converting portion which is disposed in order to convert an electromagnetic wave or an X-ray entering said unit pixel into a signal charge and which contains a first impurity; and charge transferring means adjacent to said photoelectric converting portion in an X-direction and for transferring said signal charge in a Y-direction, and
at boundaries of photoelectric converting portions adjacent to each other in the Y-direction in the unit pixels which are arranged in a one-dimensional direction of Y-direction or in two-dimensional directions of X- and Y-directions, there are alternately in Y-direction (1) isolating means for isolating said photoelectric converting portions from each other, and (2) reading means for reading a signal charge from said photoelectric converting portion into said charge transferring means.
A method of driving a solid state imaging device of the present invention is characterized in that
for said charge transferring means (typified by a CCD) possessed by continuous unit pixels A and B, first and second signal charge transfer packets having a total of eight continuous transfer electrodes are disposed; a first signal charge A generated by an electromagnetic wave or X-ray signal during a first accumulation period of said unit pixel A, and a first signal charge B generated by the electromagnetic wave or X-ray signal during a second accumulation period of said unit pixel B are read at the same timing and then added and mixed to said first signal charge packet; and a second signal charge A generated by the electromagnetic wave or the X-ray during a third accumulation period of said unit pixel A, and a second signal charge B generated by the electromagnetic wave or the X-ray during a fourth accumulation period of said unit pixel B are read at the same timing and then added and mixed to said second signal charge packet, at least one of sets of said first and second accumulation periods and said third and fourth accumulation periods having the same accumulation period.
Although the imaging device can be miniaturized, the sensitivity and the handled charged amount with respect to the amount of incident light can be improved. Although a signal charge is read from the isolating portion, the reading of a signal charge from the photoelectric converting portion can be realized without producing an afterimage.
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patent: 4847692 (1989-07-01), Tabei
patent: 4860326 (1989-08-01), Mutoh
patent: 5243180 (1993-09-01), Nam
patent: 5280186 (1994-01-01), Lee
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patent: 0 630 151 (1994-12-01), None
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Fukumoto Akira
Komobuchi Hiroyoshi
Kuroda Takao
Matsuda Yuji
Yamada Takahiro
Ho Tuan
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
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