Surgery – Endoscope – With monitoring of components or view field
Reissue Patent
2000-01-03
2001-09-04
Leubecker, John P. (Department: 3739)
Surgery
Endoscope
With monitoring of components or view field
C600S118000, C600S167000, C600S168000, C348S065000
Reissue Patent
active
RE037356
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to endoscopes and more specifically to electronic image displays for endoscopes which have a solid state imaging device and an optical system that includes a zoom lens unit for transmitting images to the solid state imaging device.
PRIOR ART
Endoscopes, which are instruments used to inspect cavities or openings, have found a great number of applications in medicine and other technology. In the field of medicine, the use of endoscopes permits inspection of organs or other biological specimens for the purpose of inspecting a surgical site, sampling tissue and/or facilitating the manipulation of other surgical instruments, usually with the objective of avoiding invasive and traumatizing surgical procedures.
Older conventional endoscopes used in medicine have an objective lens unit at their distal (forward) ends which transmits an image of the area forward of the objective lens unit to the proximal (rear) end of the endoscope for viewing in an eye-piece, the image being transmitted to the eye-piece via an image forwarding means in the form of a so-called relay lens set or an optical fiber bundle unit. In more recent years, in place of the eye-piece and at least part of the image forwarding means, it has been preferred to provide a small size solid state video imaging device, such as one constituting a CCD chip, in the imaging plane of the objective lens, and applying the output of that video imaging device via a suitable electronic transmission system to a video monitor for viewing by the user. With both types of image transmitting and viewing arrangements, the surgeon can view the displayed image and use the information conveyed by that image to manipulate the endoscope and also other surgical instruments that have been inserted into the patient via another incision or opening in the patient's body. In the case of endoscopes that incorporate a solid state video imaging device, the image seen by the objective lens unit can be observed in the display provided by the video monitor with or without magnification.
An important consideration of recent attempts to provide electronic endoscopes is to maximize the extent that the surgical site is encompassed by the endoscope image seen by the surgeon (i.e., the field of view) without any substantially detrimental loss of image resolution.
As is well known, a critical requirement of surgical endoscopes scopes is that the maximum cross-sectional dimension of the endoscope must be kept quite small in keeping with the objective of avoiding invasive and traumatizing surgical procedures. However, it also is necessary that the endoscope have an illumination lumen or duct of a size that will assure adequate illumination of the surgical site being inspected. In addition it is desirable to provide an optical system in the endoscope that maximizes the extent of the surgical site that is encompassed by the image seen by the surgeon (i.e., the field of view) without any substantially detrimental loss of image resolution. In recognition of the two-fold desire to maximize the field Of view and image resolution, efforts have been made by others to provide endoscopes with a zoom lens system. Such endoscopes typically include an objective lens stage, a zoom lens stage, and a focusing lens for making certain that the image passed by the zoom lens is in focus. In the case where a solid state imaging device is used in an endoscope, the desired focus control can be achieved and maintained by shifting the solid-state imaging device along the axis of the endoscope in a direction and by an amount sufficient to achieve the desired focus control.
An example of an endoscope having a zoom lens and a movable imaging device system is disclosed by U.S. Pat. No. 4,488,039, issued 11 Dec. 1984 to Masamichi Sato et al for “Imaging System Having Vari-Focal Lens For Use In Endoscope”. In essence the arrangement disclosed in U.S. Pat. No. 4,488,039 is one in which the position of the imaging device that is required to achieve proper focusing is estimated on the basis of the position of the zoom lens. However, the Sato et al endoscope is handicapped by the fact that the process of estimating is conducted “on the fly”, which appears to limit the accuracy and/or response time of the system with respect to optimizing continuous focusing during movement of the zoom lens.
U.S. Pat. No. 4,488,039 suggests that the endoscope may be modified so as to make its control system capable of detecting changes in the position of the imaging device and then estimating an appropriate position for the zoom lens in order to achieve proper focusing of the sensed image on the imaging surface of the imaging device. That arrangement appears to suffer from the need to estimate the appropriate position for the zoom lens unit as the imaging device is being moved, so that the system disclosed by U.S. Pat. No. 4,488,039 does not embody a practical electrical mechanical design that is relatively inexpensive to manufacture and also is characterized by an efficient and reliable mode of operation.
The endoscope described in said copending U.S. application Ser. No. 08/319,886 embodies a zoom lens unit which is under operator control, plus a CCD imaging device which also is under operator control. As the zoom lens unit position is modified, the lens system focal plane shifts (inward or outward according to the direction of movement of the zoom lens unit) causing the image seen by the CCD imaging device to become unfocussed. Also as the object of attention in the video image varies in distance from the lens system, the position of the lens system focal plane also shifts, causing the image projection seen by the CCD imaging device to become unfocussed. Accordingly, the endoscope invention of said copending U.S. application Ser. No. 08/319,886, embodies an automatic control system (hereinafter described) which serves to capture a properly focused image. The automatic control system compensates for both focal plane shifts by automatically shifting the CCD imaging device position to track the lens system focal plane, and thereby maintain proper focus at the image-receiving surface of the imaging device. The control system requires as input parameters specified by the operator both the zoom lens setting and the distance from the lens system to the object of interest (the “object distance”). With that information (plus its knowledge of the characteristics of the lens system) the control system is able to maintain proper focus under all conditions. Thus, the operator may vary the zoom and deflect distance parameters over some predetermined allowable range of values, and expect the control system to properly adjust focus to track his or her commands. However, particularly since the range of values which may be specified for either parameter is limited, it becomes advantageous to provide some form of information feedback from the control system to the operator to indicate the parameter values currently specified by the operator and their relationship to their respective permissible ranges. It also is useful to the operator to indicate, by some form of information feedback, that a particular parameter has been driven to a limit of its permissible range and hence may not be driven further in that direction.
SUMMARY OF THE INVENTION
The primary object of this invention is to provide an endoscope of the type described with means for generating feedback information to the operator to indicate the instantaneous position(s) of the zoom lens unit and/or the imaging device. The method and means chosen for providing the feedback information utilizes the video display means (e.g., TV monitor) which is used to display the optical image seen by the endoscope's objective lens. Preferably the video display means is used to simultaneously display a representation of both the zoom and object distance (focus) parameters, and also (at selected times) the limits of said parameters.
A further object of this invention is to provide an endoscope of the type comprising a m
Hori Koichiro
Thaler Herbert A.
Leubecker John P.
Pandiscio & Pandiscio
Vista Medical Technologies, Inc.
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