This application claims the priority of Japanese Patent Application No. 2000-41679 filed Feb. 18, 2000, and Japanese Patent Application No. 2000-85972 filed Mar. 27, 2000.
1. Field of the Invention
The present invention relates to an endoscope apparatus, and more particularly to an apparatus capable of changing field curvature characteristics when an object to be observed is optically enlarged among others.
2. Description of the Prior Art
In recent years, in an electronic endoscope apparatus or the like, a movable lens for variable-power has been disposed at an objective lens system at the tip end portion of a scope to optically enlarge an image of the object to be observed. This optically enlarged image is picked up by an imaging device such as CCD (Charge Coupled Device), and a video signal (image signal) outputted from this CCD is subjected to various image processing by a processor apparatus to thereby display an enlarged image for the object to be observed on a monitor.
FIGS. 16(A) and 16(B) show an example of an enlarged display image formed by the electronic endoscope apparatus, and FIG. 16(A) shows a display on the monitor, and FIG. 16(B) shows an actual cross section showing the displayed object to be observed. This FIG. 16(A) enlarges and displays a cave-in K1 of a diseased part within a circular mask M of a monitor 1, and a variable-power mechanism in the endoscope is adapted to allow a watched part to be observed by image enlargement by 70 to 100 times.
Object of the Invention
In an objective lens system of the endoscope, however, when a particularly uneven part is enlarged, astigmatism, curvature of field or the like may throw a peripheral part or a central part out-of-focus. For example, a case of FIGS. 16(A) and 16(B) will be explained. When the central part of an enlarged cave-in K1 is in focus, the periphery part goes out of focus, and when the peripheral part of the cave-in K1 is in focus, the central part goes out of focus, and the entire image may not uniformly in focus. In such a state, there is the inconvenience that particularly in a freeze-frame picture to be photographed for recording, any completely satisfactory image cannot be obtained.
Also, in the above-described enlarged image for the uneven part, it is comparatively difficult to accurately grasp what degree the depth of the recessed part, the height of the protruded part, or the like is, and if height (difference) information on this unevenness could be provided, it would be exceedingly useful to diagnose, and to deal with the watched part among others.
The present invention has been achieved in the light of the above described problems, and is aimed to provide an endoscope apparatus capable of obtaining an image by attaining excellent entire focus especially during enlargement correspondingly to a shape of unevenness or the like of the object to be observed through the use of field curvature characteristics of the lens, and of obtaining information on differences in height of the uneven shape.
In order to attain the above described object, there is, according to the present invention, provided an endoscope apparatus including: an objective lens group disposed at a tip end portion of the endoscope, capable of changing the field curvature characteristics (image surface curvature characteristics including astigmatism) by moving a movable lens; image surface curving means for operating so as to change the field curvature characteristics of this objective lens group; and driving means for driving the movable lens on the basis of the operation of the image surface curving means.
According to the present invention, there are provided two movable lenses (or lens groups) in, for example, an objective lens group, whereby the structure is arranged so as to enable both a variable-power operation and an field curvature (characteristic change) operation. Thus, when an image surface curving switch disposed in an operating unit or the like is operated, the movable lens can be driven by an actuator or the like to thereby change the field curvature characteristics. This field curvature can be caused to occur in an under direction or in an over direction with respect to a reference plane, and it becomes possible to attain focus in accordance with a shape of the recessed part by an operation in the Under direction, or in accordance with a shape of the protruded part by an operation in the Over direction.
According to another aspect of the present invention, there is provided an endoscope apparatus, including: an objective lens group, disposed at the tip end portion of the endoscope, capable of changing the field curvature characteristics by moving a movable lens; driving means for driving a movable lens for field curvature of this objective lens group; judging means for dividing an imaging area for the objective lens group into a plurality and judging whether or not the central part and the peripheral part are in focus within a predetermined range by comparing information from these divided areas; and a control circuit for executing various control on the basis of output from this judging means.
According to the another aspect of the present invention, it is compared, by comparing means, whether or not the central part and the peripheral part are in focus and this focusing or defocusing, that is, the focused state is supplied to the control circuit. This control circuit outputs, for example, a static image when the whole is in a focused state. That is, when a freeze switch is depressed, no static image is outputted if the central part and the peripheral part are not in focus, but the freeze-frame picture can be displayed on the monitor and recorded only when in focus. Also, this information on the focused state may be displayed on the monitor or the like, and be notified by another means.
According to a further aspect of the present invention, there is provided an endoscope apparatus, including: an objective lens group, disposed at the tip end portion of the endoscope, capable of changing the field curvature characteristics by moving a movable lens; driving means for driving a movable lens for field curvature of this objective lens group; operating means for operating height (difference) information of the image central part to the peripheral part from an amount of field curvature changed by the objective lens group; and output means for outputting information on differences in height obtained by this operating means.
In the further aspect of the present invention, there can be provided display control means for displaying the information on differences in height obtained by the operating means on the monitor, and contour information can be displayed as the information on differences in height.
According to the another aspect of the present invention, focus is attained in accordance with the shape of the recessed part by an operation of the field curvature characteristics in the Under direction, or in accordance with the shape of the protruded part by the operation in the Over direction. An amount of field curvature when the protruded part or the recessed part is in focus can be grasped from a state of movement of the movable lens, and information on differences in height of the central part and the peripheral part of the protruded part or the recessed part can be operated from this amount of field curvature. This information on differences in height is caused to display on the monitor in, for example, the sectional shape and height difference value, or contour and height difference value by output means or the display control means and can be outputted to equipment such as a printer.
Even in this case, there is provided judging means for dividing an imaging area for the objective lens group into a plurality and judging whether or not the central part and the peripheral part are in focus within a predetermined range by comparing information from these divided areas, and when the central part and the peripheral part are in focus within a predetermined range on the basis of judgment by this judging means, the information on differences in height is preferably displayed, whereby it is possible to maintain accurate information on differences in height.