Television – Camera – system and detail – Still and motion modes of operation
Reexamination Certificate
1998-09-28
2003-09-30
Vu, Ngoc-Yen (Department: 2612)
Television
Camera, system and detail
Still and motion modes of operation
C348S296000, C348S312000, C348S317000, C348S364000
Reexamination Certificate
active
06628328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image pickup apparatus including drive/control means operated in an all-pixel read mode for reading pixel signals from all pixels and a thinning read mode for reading pixel signals from all pixels in a thinned-out fashion, and more particularly to an image pickup apparatus capable of being smoothly switched over in operation between the thinning read mode and the all-pixel read mode.
2. Description of the Related Art
Recently, with image pickup apparatus using CCD image pickup devices, which are utilized in electronic cameras or the like, constructed of a large number of pixels, the apparatus has been designed to read pixels in a skipping fashion, i.e., in a thinned-out fashion, without reading all the pixels except recording of a still picture, for thereby achieving high-speed processing that is required, e.g., when an image is to be displayed in a liquid crystal display unit, and when the AE or AF operation is to be carried out. By operating the image pickup apparatus in such a thinning read mode, pixel signals can be read at a higher speed than an all-pixel read mode because all the pixels are not read in the thinning read mode. In the liquid crystal display unit, for example, the number of frames displayed per second can be increased, and therefore a smooth motion picture can be displayed rather than an intermittent frame picture.
When a CCD image pickup device is driven in the skipping read mode (thinning read mode), some of pixel lines are read, but the remaining pixel lines are not read. Then, if exposure is repeated many times for the pixel lines which are not read, signal electric charges may overflow from photodiodes constituting pixels of those lines and may mix into transfer lines. Also, in image pickup apparatus operated in the skipping read mode and the all-pixel read mode, when the operating mode is shifted from the skipping read mode to the all-pixel read mode, there arises a similar problem. Specifically, if signal electric charges overflow in some lines which are subjected to multiple exposures in the skipping read mode, the signal electric charges generated in the skipping read mode and still remained in the pixels of those lines may mix in signal electric charges generated in the all-pixel read mode.
SUMMARY OF THE INVENTION
The present invention has been made with a view of solving the above-mentioned problems in the conventional image pickup apparatus including drive/control means operated in a thinning read mode and an all-pixel read mode, and a main object of the present invention is to provide an image pickup apparatus which can prevent signal electric charges from overflowing in the thinning read mode, can hence eliminate the need of interlaced scanning, and is free from flickers.
According to the present invention, in an image pickup apparatus comprising a solid state image pickup device made up of a plurality of pixels constituted by photoelectric transducers which are two-dimensionally arrayed in the horizontal and vertical directions, a vertical register for receiving signal electric charges of each pixel and transferring the signal electric charges in the vertical direction, and a horizontal register for transferring the signal electric charges in the vertical register in the horizontal direction, and control means for driving and controlling the solid state image pickup device, the control means has a driving function in an all-pixel read mode for transferring the signal electric charges from all the pixels of the solid state image pickup device to the vertical registers to read pixel signals, a driving function in a thinning read mode for transferring the signal electric charges from a number n (n is one or more positive integer) of pixels for each unit of a number m (m is two or more positive integer) of pixels in the vertical direction to the vertical registers to read pixel signals, and a device shutter function for extracting the signal electric charges from each pixel to control a photoelectric conversion time, the control means being designed in the thinning read mode to carry out the operation of extracting the signal electric charges from each pixel one or more times for each read period of one frame.
By carrying out the operation of extracting the signal electric charges from each pixel one or more times for each read period of one frame when the solid state image pickup device is driven in the thinning read mode, it is possible to prevent overflow of signal electric charges from the pixels, from which the signal electric charges are not read, the overflow being otherwise caused during the operation in the thinning read mode. There can be thus provided an image pickup apparatus in which even when the same pixels are read repetitively during the operation in the thinning read mode, overflow of signal electric charges from the pixels which are not read can be prevented; hence interlaced scanning is no longer needed and the occurrence of flickers is avoided.
Another object of the present invention is to provide an image pickup apparatus which can prevent, at the time of shift from the thinning read mode to the all-pixel read mode, the signal electric charges remained in the thinning read mode from mixing in the all-pixel read mode.
According to the present invention, in an image pickup apparatus comprising a solid state image pickup device made up of a plurality of pixels constituted by photoelectric transducers which are two-dimensionally arrayed in the horizontal and vertical directions, a vertical register for receiving signal electric charges of each pixel and transferring the signal electric charges in the vertical direction, and a horizontal register for transferring the signal electric charges in the vertical register in the horizontal direction, and control means for driving and controlling the solid state image pickup device, the control means has a driving function in an all-pixel read mode for transferring the signal electric charges from all the pixels of the solid state image pickup device to the vertical registers to read pixel signals, a driving function in a thinning read mode for transferring the signal electric charges from a number n (n is one or more positive integer) of pixels for each unit of a number m (m is two or more positive integer) of pixels in the vertical direction to the vertical registers to read pixel signals, and a device shutter function for extracting the signal electric charges from each pixel to control a photoelectric conversion time, the control means being designed to carry out the operation of extracting the signal electric charges from each pixel one or more times immediately before the start of exposure when the solid state image pickup device is driven in the all-pixel read mode directly subsequent to the thinning read mode.
By carrying out the operation of extracting the signal electric charges from each pixel one or more times immediately before the start of exposure of the all-pixel read mode when the solid state image pickup device its shifted in operation from the thinning read mode to the all-pixel read mode, there can be provided an image pickup apparatus in which signal electric charges accumulated in the pixels, which are not read, due to multiple exposures during the thinning read mode are surely purged out and prevented from mixing in the all-pixel read mode.
Also, according to the present invention, in an image pickup apparatus comprising a solid state image pickup device made up of a plurality of pixels constituted by photoelectric transducers which are two-dimensionally arrayed in the horizontal and vertical directions, a vertical register for receiving signal electric charges of each pixel and transferring the signal electric charges in the vertical direction, and a horizontal register for transferring the signal electric charges in the vertical register in the horizontal direction, and control means for driving and controlling the solid state image pickup device, the control means has a d
Kijima Takayuki
Ogawa Yoshitaka
Sakurai Junzo
Yokouchi Masaki
Armstrong Westerman & Hattori, LLP.
Olympus Optical Co,. Ltd.
Vu Ngoc-Yen
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