Surgery – Endoscope – Having imaging and illumination means
Reexamination Certificate
1999-03-04
2001-05-22
Mulcahy, John (Department: 3739)
Surgery
Endoscope
Having imaging and illumination means
C600S178000, C348S069000
Reexamination Certificate
active
06234959
ABSTRACT:
BACKGROUND OF THE INVENTION
This application claims the priority of Japanese Patent Application No. 10-71324 filed on Mar. 5, 1998 which is incorporated herein by reference.
The present invention relates to an electronic-endoscope light quantity controlling apparatus, and in particular, to the contents of light source unit that can set the shielding period to execute the all-pixel reading system that can read out all the pixels accumulated in the image pickup device.
DESCRIPTION OF THE PRIOR ART
In an electronic-endoscope apparatus, for example, CCD (Charge Coupled Device) is used as a solid image-pickup device, and this CCD is structured so as to obtain an image signal (video signal) by reading out charge accumulated in units of pixels by a photoelectric conversion device. In, for example, a simultaneous type electronic-endoscope apparatus, color filters are arranged in units of pixels on the top surface of the forgoing CCD to thereby obtain a color image.
FIG. 5
shows an arrangement state for the forgoing color filters, and Mg (magenta) and Cy (cyan) pixels are arranged on, for example, an even line, and G (green) and Ye (yellow) pixels are arranged on an odd line on a picked-up surface of CCD
1
as shown. In this CCD
1
, accumulated charge (pixel signal) in units of pixels is to be obtained through these color filters.
According to a conventional color difference line sequential mix reading (pixel mix reading) system, accumulated charges of pixels on the upper and lower lines are added and mixed to be readout. For example, during first exposure, video signals of such odd field as a mixed signal of 0-line and 1-line, a mixed signal of 2-line and 3-line, . . . are readout, and during the second exposure, video signals of such even field as a mixed signals of 1-line and 2-line, a mixed signal of 3-line and 4-line, . . . are readout. Therefore, two lines of mixed signals of CCD
1
become one line of signals of field image, and one odd or even field of data are to be obtained by one exposure.
FIG. 6
shows an operation of signals read out from the foregoing CCD
1
, and in an electronic-endoscope apparatus, an odd field and an even field are formed on the basis of the O (Odd)/E (Even) signal (field signal) for each {fraction (1/60)} second (vertical synchronizing period) as shown in FIG.
6
(A). Therefore, as shown in FIG.
6
(B), signals are accumulated in accumulation (exposure) time T of an electronic shutter during the forgoing period of {fraction (1/60)} second, and the accumulation mixed signal is read out during the next {fraction (1/60)} second period. As a result, as shown in FIG.
6
(c), an odd field signal, and an even field signal are to be obtained, and for example, the (n−1)th odd field signal becomes mixed signals of (0+1) line, (2+3) line, (4+5) line . . . which are shown on the left of
FIG. 21
, and the n-th even field signal becomes mixed signals of (1+2) line, (3+4) line, . . . which are shown on the right of FIG.
21
.
These odd field signals and even field signals are interlace scanned to be formed as a one-frame image, and this image is displayed as a moving image on a monitor. Also, in the endoscope apparatus, a freeze switch is arranged in the operating unit, and when this freeze switch is depressed, a still image at the time is formed and displayed.
BRIEF SUMMARY OF THE INVENTION
In the foregoing simultaneous type electronic-endoscope apparatus, however, there is a time lag of {fraction (1/60)} second between those odd field image and even field image which are used to form the one-frame image as shown in the foregoing FIG.
6
(C), and if there is a shake of the endoscope itself, a movement of the object to be observed or the like during this period of time, there is the problem that the image quality (resolution, color shift, etc.) will be deteriorated when the still image is displayed. In other words, in the case of a moving image, it is often better to faithfully reproduce the movement and the like of the subject conversely by the foregoing mix reading system in the CCD
1
, but in the case of a still image, the resolution will be deteriorated.
Thus, the applicant sets a predetermined light shielding period and uses an all-pixel reading system for reading all pixels out from data obtained during one exposure using this period, then in order to set this shielding period, a shielding plate provided in a light source must be driven with predetermined timings to completely shield the light source. The shielding plate and a driving mechanism therefor, however, are newly added members, which complicate the configuration and increase costs.
The present invention has been achieved in the light of this problem, and its object is to provide an electronic-endoscope light quantity controlling apparatus that can reduce costs by simplifying a configuration for setting a shielding period in executing an all-pixel reading system.
SUMMARY OF THE INVENTION
In order to achieve this object, this invention is characterized by comprising an image pickup device driving circuit for using a shielding period to read out signals for all pixels accumulated in an image-pickup device during a single exposure, a diaphragm for adjusting the quantity of light from a light source, and a diaphragm controlling circuit for variably controlling said diaphragm so as to maintain the brightness of an image at a predetermined value and closing the diaphragm to obtain a complete shielding state.
Another aspect of this invention is characterized by applying the invention of the all-pixel reading system to an electronic-endoscope and forming a moving image using a pixel mix reading system at the output of the image pickup device that mixes together and outputs vertically arranged lines of image signals accumulated in the image pickup device, while forming a still image using the all-pixel reading system that uses the light shielding period to read out signals for all pixels accumulated in the image pickup device during a single exposure period.
Next, how this configuration operates if the all-pixel reading system is executed only during the formation of a still image will be described. This is, in a normal condition under which the freeze switch is not pressed, the pixel mix reading system operating when the image pickup device outputs has been selected, and pixels in two lines read out from the image pickup device as in the prior art are mixed together and output to provide a moving image that reproduces motions of an object faithfully.
When a freeze switch is depressed, the all-pixel reading system is selected to form a still image. In the all-pixel reading system, for example, during a predetermined (the first) period of {fraction (1/60)} second (a vertical synchronizing period), charges are accumulated due to exposure (the exposure time is arbitrary), and during the second period (in the next exposure), the odd lines in the image pickup device (CCD) are read out and stored in a predetermined memory. During the third period ({fraction (1/60)} second), the remaining even lines are read out and stored in a predetermined memory. To allow the even lines to be read out, the light shielding means intercepts light from a light source during the second period.
That is, if, during the second period during which accumulated charges in the odd lines are sequentially read out, subsequent charges are accumulated, as in the prior art, the remaining even lines cannot be read out. Thus, this invention eliminates the optical output during the second period (shielding period) and reads out the accumulated charges in the even lines during the third period. Thereby, the signals of all pixels of the image pickup device obtained by a single exposure can be read out.
According to this invention, a diaphragm driving mechanism installed to adjust the brightness sets the shielding period. That is, although it is essentially impossible that the diaphragm is fully closed, a diaphragm full-close pulse is output to fully close the diaphragm during the above second period in order to set a c
Higuchi Mitsuru
Takeuchi Shinji
Yamanaka Kazuhiro
Fuji Photo Optical Co., Ltd.
Mulcahy John
Snider Ronald R.
Snider & Associates
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