USRE37356E1 - Endoscope with position display for zoom lens unit and imaging device - Google Patents

Abstract

A position-indicating video display system is provided for an endoscope of the type having an objective lens, a movable zoom lens, a movable solid state imaging device for picking up the image formed by said objective lens and transferred by said zoom lens, means for generating a visual display of the image seen by the objective lens, and control means for moving the zoom lens and the imaging device so as to assure that for each position occupied by the zoom lens the imaging device is positioned so that the its image-receiving surface is in the focal plane of the zoom lens. The position-indicating video display system comprises means for generating first and second movable markers indicative of the instantaneous positions of the zoom lens and the solid state imaging device along the optical axis, and additional limit markers indicative of the maximum and minimum limits of the travel paths of the zoom lens and the solid state imaging device.

Description

PRIORITY DATA

This is a continuation-in-part of U.S. patent application Ser. No. 08/319,886, filed 7 Oct. 1994 for “Electronic Endoscope With Zoom Lens System” (Attorney Docket No. OKTA-1), now U.S. Pat. No. 5,582,576.

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 movable zoom lens unit and a movable electronic imaging device, first and second selectively operable means for moving said zoom lens unit and said imaging device respectively, and novel means for displaying the position of said zoom lens unit and/or said imaging device.

A more specific object is to provide an electronic endoscope of the type having a zoom capability with a novel means for displaying the position of the zoom lens.

Another specific object:of this invention is to provide an electronic endoscope of the type having a movable solid state imaging device with a novel means for displaying the position of the solid state imaging device.

A further object is to provide an endoscope of the type having an objective lens, a zoom lens unit for varying the effective field of view of the image transmitted by said objective lens, a solid state imaging device capable of providing an output signal representative of the image it receives from said objective lens via said zoom lens unit, an electromechanical control means for selectively changing the axial position of the zoom lens unit and/or the imaging device so as to assure that the optical image formed by the zoom lens is focused on the image-receiving surface of the imaging device, electronic display means responsive to the output signal from said imaging device for generating a visual display of the image transmitted by the objective lens, and means for causing said display means to generate an indication of the positions of said zoom lens and said imaging device in relation to predetermined end limits of the paths of movement of said zoom lens unit and said imaging device.

In the preferred embodiment of the invention, the endoscope comprises a tube in which the objective lens is mounted, means supporting said zoom lens and said solid state imaging device inside of said tube, first and second motion-transmitting means for moving said zoom lens and said imaging device respectively along the axis of said tube, whereby the spacing between said zoom lens and said objective lens and also the spacing between said zoom lens and said imaging device along the axis of said tube may be changed, a handle attached to said tube, display means for generating a display of the image seen by said imaging device, control means including manually operable switch means carried by said handle for controlling movement of said zoom lens and said imaging device by said first and second motion transmitting means, said control means being adapted to position said zoom lens and/or said imaging device so that said imaging device is substantially at the focus of said zoom lens at each position of said zoom lens, and means coupled to said display means for generating a display indicative of the positions of said zoom lens and said imaging device as they are moved between predetermined end limits. The control means comprises means for sensing the position of said zoom lens and said imaging device along the optical axis of the endoscope, a lookup table containing information as to the spacing required to be maintained between said zoom lens and said imaging device in order for the focal plane of said zoom lens to be located substantially at the image-receiving surface of said imaging device for all positions of said zoom lens system, means for accessing the data stored in said lookup table, and means for moving said zoom lens system and/or said imaging device in response to and in accordance with the accessed data.

Other objects, advantages and novel features of the invention will become more apparent from a consideration of the following detailed description when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view, partially in section, illustrating a preferred embodiment of the invention;

FIG. 2 is a perspective view similar to FIG. 1, with certain components removed to better illustrate the construction of the device;

FIG. 3 is a view similar to FIG. 2, but with additional components removed to better illustrate the construction;

FIG. 4 is a cross-sectional view on a greatly enlarged scale taken alongline4—4 of FIG. 1;

FIG. 5 is a perspective view on an enlarged scale of certain components of the endoscope, with certain components broken away;

FIG. 6 is a fragmentary exploded view on an enlarged scale of certain components of the endoscope;

FIG. 7 is an enlarged fragmentary perspective view illustrating the drive trains for the zoom lens unit and the imaging device, with portions broken away;

FIG. 8 is a side view in elevation further illustrating the drive trains for the zoom lens unit and the imaging device;

FIG. 9 is a front end view of the endoscope illustrating the disposition of the optical fibers used to illuminate, the surgical site;

FIG. 10 is a fragmentary sectional view in elevation of the elongate bushing used to support the drive rod for the imaging device;

FIG. 11 is a fragmentary sectional view on an enlarged scale illustrating how the bundle of optical fibers is terminated at the proximal end of the endoscope;

FIG. 12 is a schematic view of the electronic control console to which the endoscope of FIG. 1 is connected;

FIG. 13 is a block diagram identifying components of the control system for the endoscope, including certain components established by programming of the computer that form part of the control console;

FIG. 14 is a schematic view further illustrating the control system;

FIG. 15 illustrates the type of curves that are recorded in a lookup table that forms part of the invention;

FIGS. 16-19 are flow diagrams illustrating the mode of operation established by the computer software program embodied and/or used with the controller of the endoscope; and

FIGS. 20-28 illustrate the means provided according to this invention for generating position marker displays.

In the several views, the thickness and/or overall size of certain components are exaggerated for convenience of illustration. Thus, for example, the thicknesses of the inner and outer tubes and the diameter of the optical fibers identified hereinafter are not to scale in FIGS. 4,9 and11. Also, the same elements are identified by the same numerals in the several views.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to FIG. 1, there is illustrated an electronic endoscope comprising ahandle unit2 and an elongatetubular assembly4.Handle unit2 comprises ahousing6 with openings through which fourcontrol switch buttons8A-8D protrude. Afiber optic cable10 and anelectrical cable12 are attached to the proximal (rear) end ofhousing6. The elongatetubular assembly4 comprises a cylindricalouter tube14 which is open at its distal (front) end. The proximal end oftube14 extends intohousing6 and is secured by aclamp18 to a first portion of a mounting frame16 (FIGS.2 and8).Housing6 preferably consists of two or more mating parts that are releasably secured to one another andframe16 by suitable screw fasteners (not shown). Mounted withinouter tube14 is a cylindrical inner tube20 (FIGS. 4,5 and8) which has its distal (front) end terminating substantially in the same plane as the corresponding end of the outer tube. The proximal end ofinner tube20 extends beyond the corresponding end ofouter tube14 and is anchored by a clamp22 (FIG. 8) to a second portion offrame16.

As seen in FIGS. 4 and 9 the inner tube is smaller than and is mounted eccentrically to the outer tube, so as to leave a crescent shaped area to accommodate a plurality of optical fibers28 (FIGS. 9 and 11 ) that are used to transmit light to illuminate the surgical site, i.e., the objective lens field of view. The distal (forward) ends offibers28 may (but need not) be bonded to one another by a suitable cement such as an epoxy resin; in either case, the fibers are locked in place between the two tubes, with their forward ends being optically polished and terminating substantially flush with the plane of the distal end edge of the outer tube.Fibers28 project out of the rear end ofouter tube14 and are collected in aprotective tubing30 preferably made of a material such as a silicone rubber. The rear ends of fibers are captured in aferrule32 that is used to connect it tocable10. The rear end surfaces offibers28 are optically polished.

Referring now to FIGS. 2,4,5 and10, mounted within and locked toinner tube20 is anelongate bushing34 that has asleeve bearing36 located at each end of its central bore or lumen35 (FIG.10).Bearings36 are made of a material having a low coefficient of friction. The proximal (rear) end ofbushing34 terminates substantially flush with the corresponding end ofinner tube20. The forward end ofbushing34 terminates intermediate the opposite ends of tube20 (FIG.5). As seen in FIG. 4, bushing34 has a generally cylindricalouter surface38 sized so that it makes a close or tight fit with the inner surface ofinner tube20. That generally cylindrical outer surface of the bushing is disrupted by three axially extendinggrooves40,42 and44.Grooves40 and42 are identical in shape and are diametrically opposed to one another, whilegroove44 is somewhat deeper. The purpose ofgrooves40,42 and44 is described hereinafter.

As seen in FIGS. 1,2,3,5 and6, mounted within the front end of and fixed toinner tube20 is anobjective lens unit48. Details of the objective lens unit are not provided since such units are well known to persons skilled in the art. See, for example, U.S. Pat. Nos. 4,488,039; 4,491,865; 4,745,470; 4,745,471; 4,832,003; 4,867,137; and 5,122,650. However, it is to be appreciated that the objective lens unit may consist of one or more lenses.Inner tube20 may be fitted with a separate transparent window member (not shown) disposed at its front end in front of the objective lens unit, or the front element of the objective lens unit may serve as the window.

Also disposed withininner tube20 is a cylindrical video imaging unit50 (FIGS. 2,3,5,6). Exact details ofimaging device50 are not illustrated since its form is not critical to the invention and instead it may take various forms, e.g., it may be like the ones described and illustrated in U.S. Pat. Nos. 4,448,039; 4,491,865; 4,867,137; and 5,166,787. Unit5O comprises a solid state CCD semi-conductor imaging devise (not shown), preferably one comprising a CCD chip as shown in U.S. Pat. Nos. 4,756,470; 4,745,471; and 5,021,888, mounted within acylindrical housing52 that is sized to make a close sliding fit ininner tube20. As seen in FIGS. 5 and 6, the forward end ofhousing52 is provided with a cylindricaltubular extension54 that serves as an aperture for the solid state imaging device. Also, although not shown, it is to be understood that the solid state CCD device has a lead frame or chip carrier with terminal pins adapted to mate with a conventional connector (not shown) on the end of a multi-strand wire cable (also not shown) that extends rearwardly ingroove44 ofbushing34 and is coupled toelectrical cable12, whereby the imaging device is coupled to external electronic circuits as hereinafter described.

Also mounted withininner tube20 is a zoom lens unit60 (FIGS. 2,3,5 and6). Details of the zoom lens unit are not provided since its exact form is not critical to the invention and also since such units are well known to persons skilled in the art of optics (see, for example, U.S. Pat. Nos. 4,570,185 and 4,781,448).Zoom lens unit60 may comprise one or more lenses, according to the desired zoom range and image resolution. In the preferred embodiment of the invention, the lens or lenses ofzoom lens unit60 are contained within acylindrical housing62 that is sized to make a close sliding fit ininner tube20.

Separate means are provided for movingimaging device50 andzoom lens unit60, such means taking the form of electrically powered drive means and motion transmitting means as shown in FIGS. 2-8.

The motion transmitting means forimaging device50 comprises acylindrical drive rod66 that extends throughbushing34 and makes a close sliding fit with its twoend sleeve bearings36.Rod66 has a length sufficient for its opposite ends to project from the corresponding forward and rear ends ofbushing34 when the rod is in both its distal (forward) and proximal (rear) limit positions which are described hereinafter.Video imaging unit50 is attached to the distal (front) end ofrod66 by a cylindrical coupling member67 (FIGS. 3,5,6) that is sized to make a close sliding fit ininner tube20. Couplingmember67 has a pair of forwardly extending, diametrically opposed arms69 (only one of which is visible in FIGS. 5 and 6) that have their forward ends connected to the imaging unit, whereby the imaging unit will move withrod66 when the latter is moved axially relative toinner tube20.

As seen in FIGS. 3,7 and8, the proximal (rear)end ofrod66 is provided with a series of evenly spacedgear teeth68, which permitrod66 to function as a first gear rack.Gear teeth68 extend over a relatively short length ofrod66 and terminate short of the proximal (rear) end of the rod. The portion ofrod66 that protrudes from the rear end ofbushing34 extends through and is slidably mounted by abushing70 that is mounted in aportion72 offrame16. Mounted onrod66 between its proximate end andteeth68 is astop member74 which is positioned to be intercepted byportion72 offrame16 when the rod is moved forward.Stop member74 andframe portion72 coact to determine a first (forward) limit position forrod66 andimaging device50. A second (rear) limit position forrod66 andimaging device50 is determined by engagement of the proximal (rear) end ofimaging device housing52 with the forward end surface ofbushing34.

The drive means forimaging device50 comprises a reversible electrical d.c.motor80 attached to frame16.Motor80 is identified hereinafter as the “focus motor” since in the invention's automatic mode of operation its function is to moveimaging unit50 so that the image-receiving surface of its CCD component is located in the focal plane ofzoom lens unit60. The output shaft ofmotor80 carries apinion gear84 that forms part of a gear system fordrive rod66.Gear84 meshes with asecond pinion gear86 affixed to ashaft88 that is rotatably supported byportions90 and92 (FIG. 7) offrame16.Shaft88 in turn carries a gear94 (FIG. 7) that meshes withteeth68 onrod66, whereby rotation ofshaft88 by operation ofmotor80 will cause linear motion ofshaft66 andimaging device50 in a direction determined by the direction of movement of the output shaft of that motor.

As seen in FIGS.2 and4-8, the motion-transmitting means forzoom lens unit60 comprises two elongateflat rods100A and100B that are sized to snugly and slidably fit ingrooves40 and42 ofbushing34.Grooves40 and42 have a depth that assures thatrods100A and100B will not protrude beyond the periphery ofbushing34. The front (distal) ends ofrods100A, B are connected to housing62 of the zoom lens unit. It is to be noted that couplingmember67 has two diametrically opposed grooves71 (only one is shown in FIG. 6) to slidably accommodaterods100A and100B withintube20. Grooves71 are sized so as to make a close sliding fit withrods100A, B and also so thatrods100A and100B will not protrude beyond the periphery of couplingmember67. The rear ends ofrods100A,100B are attached to acollar101 that surrounds and makes a close sliding fit withrod66. The proximal (rear) ends ofrods100A, B also are provided with a series of evenly spaced gear teeth102 (FIG.7).

The drive means forzoom unit60 comprises a reversible electrical d.c.motor106. Both it andmotor80 are attached to frame16 by aremovable clamp82.Motor106 is identified hereinafter as the “zoom motor”. The output shaft ofmotor106 carries apinion gear108 that meshes with apinion gear110 that is mounted on and secured to ashaft112. The latter is rotatably mounted to mutually spacedportions114,116 offrame16.Shaft112 carries two axially spacedgears120A and120B that mesh withteeth102 onrods100A and100B respectively, whereby rotation ofshaft112 by operation ofmotor106 will cause linear motion ofrods100A and100B, and therebyzoom lens unit60, lengthwise ofinner tube20 in a direction determined by the direction of rotation of the output shaft of the motor. Axial movement ofzoom lens unit60 is limited by two separate stop means. The forward limit position is determined by engagement ofcollar101 with two stop pins103 affixed to frame16. The rear limit position is determined by engagement ofcollar101 withframe portion72. The two mechanically-determined limit positions are set so as to permit the zoom lens unit a suitable total travel distance therebetween.

Referring now to FIG. 13, the housings offocus motor80 andzoom motor106 include position-sensing encoders represented schematically at120 and122 that are coupled to the output shafts of the motors and are designed to provide pulse-type signal outputs that are polarized plus or minus according to the direction of movement of the output shafts ofmotors80 and106 respectively.Shaft encoders120 and122 may take various forms but preferably they are incremental digital encoders. Because incremental position-sensing shaft-coupled encoders are well known, details of construction of the encoders are not provided herein.

FIG. 12 diagrammatically illustrates anelectronic console130 to which the endoscope is coupled. Essentially the console comprises alight source134 for the endoscope, an electronic controller comprising a digital computer138 (which includes a microprocessor and associated memory, control and input and output circuits), adisplay module140 that includes a CRT display device (FIG. 20) whereby the surgeon or other user may monitor the images seen by the endoscope, anelectronic memory device142, preferably but not necessarily in the form of an E-prom, that serves as a zoom/focus lookup table as hereinafter described, and apower supply132 for the solidstate imaging unit50,motors80 and106, and the electronic controller.Power supply132,light source134,computer138,display module140 and E-prom142 are interconnected as represented schematically in FIG. 12 so as to permit the mode of operation described hereinafter. Although not shown, it is to be understood thatpower supply132 includes a manually operated main power switch (not shown) which is used to turn the instrument “on” and “off”.

Optical fiber cable10 is coupled to console130 so as to be able to transmit light fromlight source134 tolight fibers28, whereby when that light source is energized by operation of the controller, the resulting light beam will illuminate the objective field of view.Multi-wire cable12 is connected at its outer end topower supply132 andcomputer138; at itsinner end cable12 has certain of its wires coupled by a connector (not shown) to terminals of the CCD chip ofimaging device50 and others of its wires connected tomotors80 and106 and the control switches associated withbuttons8A-8D.

Referring again to FIG. 13, theswitch buttons8A and8B form part of twofocus control switches144A and144B, whileswitch buttons8C and8D form part of two zoom control switches144C and144D. Preferably, a second like set of foot-operated switches (not shown), are added in parallel withswitches144A-D so as to give the surgeon the option of controlling maneuvering ofimaging device50 andzoom lens unit60 using one of his feet rather than one of his hands. As explained further hereinafter, operatingswitch144A will energizefocus motor80 so as to cause the imaging device to move forward toward the distal end ofinner tube20, while operatingswitch button144B will energizefocus motor80 so as to cause reverse movement of the imaging device. Similarly, operatingswitch button144C will energizemotor106 so as to cause the zoom lens unit to move forward toward the distal end ofinner tube20, while operatingswitch144D will energizemotor106 so as to cause reverse movement of the zoom lens unit. Moving the zoom lens unit forward causes the field of view seen by the imaging device to narrow while moving the zoom lens unit rearward causes the field of view to widen. It is preferred that the zoom lens unit be designed to “zoom” between a field of view of about 20 degrees to one of about 70 degrees.

Computer138 is configured by its software program to provide anobject distance counter160, a focus/CCD position counter162, and azoom position counter164. The computer is arranged to provide a control signal to a focusmotor drive circuit166 that preferably forms part of thecontroller130.Switches144A and144B are connected to a focus switch input circuit represented schematically at168 that provides an input to objectdistance counter160, whileswitches144C and144D are connected to a zoomswitch input circuit170 that provides control signals to a zoommotor drive circuit172.

Counters162 and164 provide outputs that permitcomputer138 to determine the extent of rotation of the output shafts ofmotors80 and106 from pre-selected positions which are stored in E-prom142, whereby at any given time the counts in the counters represent the exact positions ofimaging device50 and zoom lens unit60 (in relation to the pre-selected reference positions along the axis of tube20). As illustrated in FIG. 14, the computer is configured so that (1) the outputs fromobject distance counter160 and zoomposition counter164 are applied to E-prom142 to obtain a position data output signal according to those counter outputs and (2) the output signal obtained from E-prom142 and the output of focus/CCD position counter162 are applied to a comparator or adder174 (established by computer programming), with the output of the comparator being an error signal that is supplied to focusmotor drive166.

FIG. 15 relates to the kind of data that constitutes the zoom/focus lookup intable E-prom142. In FIG. 15, each of the curves A-E is a plot of different positions of (1) the zoom lens in relation to the objective lens (“Zoom”) versus (2) the corresponding distances between the CCD imaging device and the objective lens unit (“Focus”) that is required to assure that the image-receiving surface of the imaging device is in the focal plane of the zoom lens unit. Each of the curves A-E is for different object distances. As used herein, the term “object distance” means the distance measured from the objective lens to the viewed object. By way of example, the viewed object may be a human organ or other surgical site. Also by way of example but not limitation, the curves A, B, C, D and E may represent object distances of 50, 75, 100, 125 and 150 mm. respectively. Curves A-E are merely for illustration and are not intended to constitute representations of actual data stored inE-proms142. However, specific data constituting the relative positions of the CCD imaging unit (“Focus”) and the zoom lens unit (“Zoom”) required to achieve correct image focusing on the CCD imaging unit for different object distances are stored in E-prom142 and are accessed by the computer during execution of the program illustrated in FIGS. 17-20.

The data constituting the focus/zoom lookup table stored in E-prom142 are pre-calculated according to the specific parameters of the lenses embodied inobjective lens unit48 andzoom unit60, with such pre-calculation involving ray tracing and computer computation. No attempt is made herein to present specific data stored in the E-prom lookup table, since such data will vary with lens parameters and also since the procedure for deriving that data is well-known to persons skilled in the art.

FIGS. 16-19 are flow charts illustrating some of the software program forcomputer138. Some or all Of the software program and the lookup table may be permanently installed via firmware, or may be loaded into the computer from an external storage medium at the time of use. In either case, the program is designed so that after power has been applied to the system, the operator can cause the computer to automatically execute an initializing “reset” routine that results inmotors80 and106 shiftingimaging device50 andzoom unit60 to predetermined positions intermediate their mechanical limits, those predetermined positions being such that the image of a viewed object will be in focus on the image-receiving surface of the CCD imaging device when the front end of the endoscope is positioned to provide an object distance value of “n” mm, “n” being an arbitrary value selected for the initializing routine.

Operation of the endoscope is described hereinafter with reference to FIGS. 13-19. The control console is provided with a button-type reset switch (not shown) that is depressed by the physician or other user after the power has been turned on, thereby causing the computer to execute the aforementioned reset routine which is illustrated in FIGS. 18 and 19. That reset routine first involves operation ofmotors80 and106 so as to driveimaging device50 andzoom unit60 in an “UP” (forward) direction until their forward mechanical limits are reached, whereupon the mechanical load on the output shafts of the motors causes those shafts, and hence thecorresponding encoders122 and124, to stop. Stopping ofencoders122 and124 causescomputer138 to turn offmotors80 and106 if no pulses have been generated by both encoders for 0.5 milliseconds (“ms”).

As soon as both motors have been turned off, the computer (1) resetscounters162 and164 to zero, (2) setsobject distance counter160 to a predetermined count “n” representing the desired initial object distance, and (3) actuateszoom motor106 and causes it to move the zoom lens unit “Down” (rearwardly) to a predetermined start-up or reset position intermediate its distal and proximal mechanical limit positions. That start-up position is determined when the count incounter164 equals a predetermined “start-up value” (see FIG. 18) accessed by the computer as part of the reset routine. Then motor106 is turned off and the computer actuatesfocus motor80 and causes it to moveimaging device50 in a “Down” (rearward) direction to a predetermined start-up position, the arrival at that start-up position being determined when the count in focus (CCD)position counter162 as presented tocomparator174 matches a predetermined start-up value accessed from theE-prom142 by the computer as part of the reset routine. At this points, the counts incounter162 and164 are start-up counts, whereby at any given time the control system can determine new changed positions ofimaging device50 andzoom lens unit60 by determining how much the current counts in those counters differ from the start-up counts.

At this point, a focus motor servo control loop(FIG. 19) is activated, which control loop provides the following operation. As theimaging device50 is moved in a “Down” direction to its predetermined start-up position,encoder120 will generate pulses that are accumulated incounter162. The output ofobject distance counter160, preset by the computer to the predetermined start-up value “n” and the output of zoommotor position counter164, are applied to E-prom142 to obtain an output from the zoom/focus lookup table that has a value representing the desired imaging device position. The output from E-prom142 (representing the desired CCD position) and the output of CCD position counter162 (representing the actual CCD position) are applied tocomparator174. Depending on whether the actual CCD position represented by the output ofcounter162 is “Up” or “Down” relative to the desired CCD position represented by the output ofE-prom142, the error signal produced bycomparator174 will be positive (+) or negative (−). If it is positive, and if the actual CCD position is below a predetermined upper limit value (the latter value is stored in the computer memory), focusmotor80 will be caused to move the imaging device in an “Up” direction. If the error signal is negative and the actual imaging device position is above a predetermined lower limit value stored in the computer memory, the focus motor will be caused to move the imaging device in a “Down” direction. In either case, the count of focus positioncounter output162 will change and consequently the error signal fromcomparator174 will change in value toward zero. At zero error signal value, the zoom motor will stop. Although not necessary, it is preferred for reasons of stability and accuracy, to program the focus servo control loop to periodically make a comparison incomparator174, preferably every 20 microseconds as indicated in FIG.19. This involves clearing the comparator (adder) at the start of each new comparison operation, as noted in FIG.19.

At this point, if the distance between the endoscope and the viewed object (“object distance”) is at the value for which the imaging device and the zoom unit are preset as a result8f the reset routine, the image that is displayed bydisplay device140 will be in focus. Subsequently, if the object distance changes, e.g., as a result of the endoscope being moved, or the surgeon's point of interest is changed, the displayed image may go out of focus. In such event, the surgeon can reacquire a sharp focus by operating one or the other ofbuttons8A and8B. The resulting operation will cause counter160 to be either increased or decreased by clocked pulses whileswitch8A or8B respectively is depressed. This changed value incounter160 is applied to the zoom/focus lookup table, resulting in a new output value being transferred from the lookup table tocomparator174. The result is a change in the error signal output fromcomparator174, which in turn is utilized by the servo control system to further operatemotor80 until the adjusted CCD position as measured bycounter162 again results in a zero error signal.

Once sharp focusing has been achieved, the image will remain in focus on the image-receiving surface of the CCD imaging device even though the operator utilizesbuttons8C or8D to operate the zoom motor so as to zoom up or down with regard to the object being viewed. As seen in FIG. 17, thezoom motor encoder122 tracks zoom motor position, and the output of the zoom motor encoder is used to drive the E-prom to a new output value. The new value obtained from E-prom142 is compared with the signal output ofcounter162 to modify the error signal. That error signal is then utilized in the servo-control loop to cause the focus motor to operate in a direction and for a duration sufficient to locate the CCD imaging device at a position which assures that sharp focusing of the image is achieved despite the change in field of view caused by zooming up or down.

It is to be appreciated that when its main power switch (not shown) is turned on and/or the reset switch is actuated, the control system described above will automatically set theimaging device50 and the zoom lens unit to a preselected position which provides a predetermined field of view with sharp focusing at the CCD device of the image seen by the objective lens. Thereafter, the operator has the advantage that by depressing either of thebuttons8C and8D, the field of view may be changed without changing the object distance between the objective lens and the object being viewed. Additionally, if the need arises to change the position of the endoscope so as to change the object distance, the operator has the option of utilizingbuttons8A and8B to refocus the image, and also the option of utilizingbuttons8C and8D to change the field of view without again having to utilize thebuttons8A and8B to change the position of the imaging device in a direction to restore or maintain a sharp image for viewing on displayingdevice140.

FIG. 20 generally illustrates in diagrammatic form a system for providing an electronically generated display of the optical image that is passed by theobjective lens unit48 andzoom lens unit60 toimaging device50. An endoscope video signal derived from imagingdevice50 is processed by conventional video circuits identified generally at200 to provide signals that are applied to aTV monitor204 so as to cause the latter to reproduce as a TV image the optical image seen by the endoscope's objective lens unit. Thevideo circuits200 and the circuits hereinafter described are preferably embodied in display module140 (FIG.12). The signal processing video circuits may take various forms known to persons skilled in the art and do not constitute part of the present invention. Suffice it to say that the optical image is reproduced with a magnification and field of view determined by the position of the zoom lens unit and a focusing accuracy determined by the position ofimaging device50 along the endoscope's optical axis.

Turning now to FIGS. 21 to28, the present invention involves provision of means for generating video image markers (“indicators”) that provide the surgeon with an indication of the instantaneous zoom and focus settings as well as the maximum and minimum zoom and focus settings. Whenfocus control button8A or8B is operated, two vertically spaced rectangles are created on the TV monitor screen, one representing the instantaneous setting of the imaging device (focus display) and the other representing the instantaneous setting of the zoom lens unit (zoom display). The same markers are displayed if either of thezoom control buttons8C and8D are depressed. For convenience, these rectangular markers representing instantaneous settings are identified as “bar-graph displays” in recognition of the fact that they move horizontally in synchronism with movement of the imaging device and the zoom lens unit so that their horizontal positions provide an indication of the instantaneous positions of the imaging device and the zoom lens unit. Additionally, as the imaging device and the zoom lens unit approach either of their end limits of travel, i.e. their maximum or minimum limits, the display control system additionally generates a limit position marker in the form of an additional rectangular display The instantaneous rectangular position display markers are displayed only when one of thecontrol buttons8A-8D is operated and for a brief period after the button has been released, and a maximum or minimum limit marker is generated only as the imaging device or the zoom lens unit, as the case may be, approaches its maximum or minimum limit position respectively The maximum and minimum limit markers are extinguished at the same time as the instantaneous position markers.

As represented in FIG. 21, the system for generating and controlling the position and limit marker displays comprises a videosync stripper circuit206 which recovers or develops from the endoscope video signal output of imaging device50 a vertical sync signal (V-Sync), a horizontal sync signal (H-Sync), and also a clock signal identified hereinafter as a “pixel clock”. Those signals are applied as input signals to marker display control circuits, identified generally by numeral210 which include inter alia, apixel counter212, aline counter214, and pixel andline comparators216 and218. Also supplied as inputs to the marker display control circuits are operator-controlled zoom and object distance signals. The zoom and object distance signals are the outputs of thezoom position counter164 andobject distance counter160 shown in FIG.13. The output fromcounter164 is the zoom magnification setting in the form of a digital value while the output fromobject distance counter164 is the object distance setting in the form of a digital value. Additional inputs to the marker display control circuits are two zoom-related signals identified as “Minimum Zoom” and “Maximum Zoom”, two object distance-related signals identified as “Minimum Object Distance” and “Maximum Object Distance”, and a “Control Button” signal that is generated whenever any one of thecontrol buttons8A-8D is depressed.

FIGS. 22 and 23 illustrate how the minimum and maximum zoom and object distance signals are generated. In FIG. 22, the signal output fromzoom position counter164 is applied to twocomparators224 and228. Predetermined maximum and minimum reference value signals are applied as second inputs tocomparators224 and228 respectively. When the count fromzoom position counter164 equals the predetermined minimum reference value,comparator224 will produce the “Minimum Zoom” signal. A “Maximum Zoom” signal is generated whenever the zoom count fromcounter164 equals the predetermined maximum reference value.

FIG. 23 shows a similar circuit arrangement for generating the “Minimum Object Distance” and “Maximum Object Distance” signals, with the object distance signal input tocomparators232 and234 constituting the output from object distance counter160 (FIG.13), and the second input to those comparators comprising predetermined minimum and maximum reference values.

Turning now to FIGS. 24 and 25. The V-Sync and H-Sync signals are applied as inputs toraster line counter214, the H-Sync and pixel clock signals are applied as inputs topixel counter212, and the V-Sync signal and the control button signal are applied as inputs to aframe counter238. Theline counter214 counts H-Sync pulses and is initialized to zero by the V-Sync signals. Thepixel counter212 counts Pixel Clock pules and is initialized to zero by the H-sync. Theframe counter238 is initialized to zero by pressing any of thecontrol buttons8A-8D and counts V-Sync pulses after the pressed control button is released.

The output ofline counter214 is applied as an input to twoseparate line comparators218A and218B.Comparator218A is adapted to produce an “Enable Focus Display” signal whenever the line count is equal to 32 or 40 or is at an in-between value.Comparator218B is adapted to produce an “Enable Zoom Display” signal whenever the line count is equal to 232 or 240 or is at an in-between value. Both the zoom and focus indicators (markers) are displayed when any control button is pressed. Additionally, the system is arranged so that the markers continue to be displayed for one second after the depressed control button is released. The latter action is achieved by means offrame counter238, the latter being adapted to count frames (i.e., V-Sync pulses), for the duration of one second. In this connection it is to be understood that preferably the V-Sync pulses are generated at a 60 cycle rate, and thatframe counter238 is arranged so as to generate an output signal when it has counted 60 V-Sync. pulses. The resulting output signal is identified as the “Enable Display For One Second” signal.

The output ofpixel counter212 is applied to threedifferent comparators216A,216B, and216C.Comparator216A produces an “Enable Minimum Display” signal when the pixel counter has a count between 50 and 56;comparator216B produces an “Enable Maximum Display” signal when the pixel count has a count between and including 142 to 148, andcomparator216C generates an “Enable Bar-Graph Display” signal whenever the pixel counter has a count in the range of 58-140.

FIG. 26 illustrates how the system also is designed to produce two control signals identified as “Enable Focus Indicator Display” and “Enable Zoom Indicator Display”. The means for producing these control signals comprises a bar-graph pixel counter250, twocomparators252 and254, and amultiplexer256. The bar-graph pixel counter250 is clocked by the pixel clock pulses derived from the endoscope video signal. Predetermined initial minimum values for zoom and focus are applied sequentially to the bar-graph pixel counter according to the line count. This is accomplished by applying predetermined object distance minimum value signals and zoom minimum value signals inputs tomultiplexer256, with the latter being controlled by application of the “Enable Focus Display” signal and the “Enable Zoom Display” signal produced byline comparators218A and218B, respectively. When the line counter has a value in the range of 32-40,multiplexer256 is switched by the “Enable Focus Display” signal so as to pass the predetermined object distance minimum value signal to bar-graph pixel counter250, thereby causing the latter to be preset to the minimum object distance value. When the line count is 232-240,multiplexer256 is switched by the “Enable Zoom Display” signal so as to pass the predetermined zoom initial minimum value signal to counter250 so as to preset the counter to that minimum value.

Comparators252 and254 also receive the outputs ofobject distance counter160 and zoomposition counter164. When the output from object distance counter160 matches the output of bar-graph pixel counter250,comparator252 will produce the “Enable Focus Indicator Display” signal. The “Enable Zoom Indicator Display” signal is generated when the signal fromzoom counter164 matches the value of the output of bar-graph pixel counter250.

As shown in FIGS. 27A to27F, the invention further comprises six “AND” gate output circuits that cause the several indicators (markers) to be displayed on the monitor screen. For this preferred embodiment each output AND gate circuit generates an “Insert Video White” signal that is applied to video monitor204 so as to cause the latter to display a white marker on its screen.

FIGS. 27A and 27B show AND gate circuits for causing the focus and zoom position markers to be generated. In FIG. 27A, ANDgate260 generates an “Insert Video White” signal for producing the focus position marker in response to the “Enable Focus Display”, “The Enable Bar Graph Display” and the “Enable Focus Indicator Display” signal; also, in response to the “Enable Display For One Second” signal, it maintains that insert video white signal for an additional second after the focus control button that was depressed has been released. In FIG. 27B, the ANDgate264 generates an “Insert Video White” signal in response to the “Enable Zoom Display”, “Enable Bar Graph Display” and the “Enable Zoom Indicator Display” signal and again, in response to the “Enable Display For One Second” signal, it also maintains that insert white signal for an additional second after the depressed zoom button has been released.

The two AND gate units of FIGS. 27C and 27D are similar to those of FIGS. 27A and 27B, except that with ANDgate266 the “Enable Maximum Display”, “Enable Focus Display” and the “Maximum Object Distance” signals are used as inputs to the gate so as to cause the latter to produce an “Insert Video White” signal to generate a maximum focus limit marker, and withgate268 the “Enable Minimum Display”, “Enable Focus Display” and the “Minimum Object Distance” signals are used as inputs to the gate to generate an “Insert Video White” signal that produces the minimum focus limit marker. The “Enable Display For One Second” signal maintains the gate output for an additional second after the depressed focus button has been released.

The ANDgates270 and272 of FIGS. 27E and 27F are similar except that the “Enable Maximum Display”, “Enable Zoom Display” and “Maximum Zoom” signals are used to causegate270 to produce an “Insert White Video” signal output to cause the monitor to display the minimum zoom limit marker. In FIG. 27F, the “Enable Minimum Display”, “Enable Zoom Display” and “Minimum Zoom” signals are used to causegate272 to produce an “Insert White Video” signal output to cause the monitor to display the minimum zoom limit marker. The “Enable Display For One Second” signal maintains the output ofgate272 for an additional second after the depressed zoom button has been released.

FIG. 28 illustrates the position and limit marker displays provided by this invention. Therectangle276 represents the border of the endoscope image display on the TV monitor screen. For convenience of illustration, no endoscope image is presented in FIG. 28, but it is to be understood that the markers hereinafter described are superimposed on the displayed endoscope image.

The relativelylarge rectangle280A represents the minimum end limit for the object distance (focus) parameter, while thesmaller rectangle282 represents the instantaneous bar-graph value of object distance parameter. The minimumfocus limit marker280A appears only when the object distance value represented bymarker282 approaches a predetermined minimum value. In practice, the circuits are set so that the instantaneous position markers and the limit markers never overlap. Instead it is preferred that each limit marker be generated so that it is spaced approximately ¼ inch from the corresponding instantaneous position marker when the latter has reached the limit of its travel. When the CCD imaging device is backed away from the object lens, therectangle282 moves to the right on the TV display to indicate a larger object distance value. As therectangle282 moves to the right, the larger end limitrectangular marker280A will disappear. When the object distance value represented byrectangular marker282 approaches its other (maximum) end limit, another large rectangle (shown in phantom at280B) similar torectangle280A will appear at the right hand end of theimage window276.

The relatively large and relatively smallrectangular markers286A and288 in FIG. 28 represent the maximum zoom position limit and the instantaneous zoom positions respectively. Themarker288 moves to the left as the zoom lens unit is moved forwardly in the endoscope. The largerend limit marker286A appears only whenmarker288 approaches the maximum end limit for the zoom lens unit, and disappears whenmarker288 moves away from that markers end limit. Another minimumend limit marker286B is displayed at the left hand side of the TV monitor screen when the instantaneous zoom position marker approaches the minimum (forward) end limit for the zoom lens unit.

The marker display capability provided by the present invention is advantageous to the operator in providing feedback as to the parameters of the zoom lens unit and the imaging device in relation to their maximum and minimum end limits.

The invention also offers the advantage that it is susceptible of various modifications. Thus, the shape of the markers is not limited to rectangles, and instead other shaped markers may be used. Also the marker display circuits can be modified so as to increase or decrease the length of time the markers are displayed and also to change the vertical positions of the markers on the TV monitor screen. Different forms of imaging devices also may be used. For example, the imaging component of the invention may utilize a BBD semiconductor imaging device rather than a CCD solid state element, as suggested by U.S. Pat. No. 4,488,039. Similarly, the number of lenses in the objective lens unit and also in the zoom lens unit may be changed without affecting operation of the invention.

Other possible modifications and advantages of the invention will be obvious to persons skilled in the art.

Claims (14)

What is claimed is:

1. An endoscope apparatus comprising:

a handle assembly;

a tube having a distal end and a proximal end, said tube being mounted within said outer tube and having its proximal end anchored to said handle assembly;

an objective lens unit mounted in the distal end of said tube;

a shaft having a distal end and a proximal end, said shaft being disposed within and movable along the axis of said tube;

a solid state imaging device disposed within said tube and attached to said distal end of said shaft so as to be movable therewith along the axis of said tube, said imaging device having an a light receiving surface for receiving an image transmitted by said objective lens unit and being capable of generating an output signal representative of the image transmitted by said objective lens unit;

a zoom lens unit disposed within said tube between said objective lens unit and said imaging device for transmitting images seen by said objective lens unit to said imaging device, said zoom lens unit being moveable along the axis of said tube relative to said objective lens unit so as to cause the magnification of the image passed by said objective lens unit to be changed in accordance with the axial position of said zoom lens unit in relation to said objective lens unit;

first and second drive means attached to said handle assembly;

a first motion-transmitting means coupling said first drive means to said shaft, whereby operation of said first drive means will cause axial movement of said imaging device relative to said objective lens unit;

a second motion-transmitting means coupling said second drive means to said zoom lens unit whereby operation of said second drive means will cause axial movement of said zoom lens unit relative to said objective lens unit and said zoom lens unit;

control means for operating said first and second drive means;

display means responsive to said imaging device output signal for generating a video reproduction of the image passed by said objective lens unit; and

electronic means responsive to said imaging device output signal for causing said display means to generate a video image representative of the position of at least said zoom lens unit or said imaging device.

2. Apparatus according to claim1 wherein said electronic means is adapted to cause said display means to generate a video image representative of the positions of both said zoom lens unit and said imaging device.

3. Apparatus according to claim1 wherein said zoom lens unit is movable between a first minimum position and a second maximum position, and said electronic means is adapted to cause said display means to generate a first image representative of said minimum position of said zoom lens unit and a second image representative of said maximum position of said zoom lens unit.

4. Apparatus according to claim3 wherein said electronic means is adapted to cause said display means to generate an additional image representative of the instantaneous position of said zoom lens unit.

5. Apparatus according to claim1 wherein said imaging device is movable between a first minimum position and a second maximum position, and said electronic means is adapted to cause said display means to generate a first image representative of said minimum position of said imaging device and a second image representative of said maximum position of said imaging device.

6. Apparatus according to claim5 wherein said electronic means is adapted to cause said display means to generate an additional image representative of the instantaneous position of said imaging device.

7. An endoscope apparatus comprising:

a handle assembly;

an outer tube having a distal end and proximal end, with said proximal end anchored to said handle assembly;

an inner tube having a distal end and a proximal end, said inner tube being mounted within said outer tube and having its proximal end anchored to said handle assembly;

an objective lens unit mounted in the distal end of said inner tube;

a shaft having a distal end and a proximal end, said shaft being disposed within and movable along the axis of said inner tube;

a solid state imaging device disposed within said inner tube and attached to said distal end of said shaft so as to be movable therewith along the axis of said inner tube, said imaging device having a light-receiving surface to for receiving an image transmitted by said objective lens unit and being capable of generating an output signal representative of the image transmitted by said objective lens unit;

a zoom lens unit disposed within said inner tube between said objective lens unit and said imaging device, said zoom lens unit being moveable along the axis of said inner tube relative to said objective lens unit so as to cause the magnification of the image passed by said objective lens unit to be changed in accordance with the axial position of said zoom lens unit in relation to said objective lens unit;

first and second drive means attached to said handle assembly;

a first motion-transmitting means coupling said first drive lens means to said shaft, whereby operation of said first drive means will cause axial movement of said imaging device relative to said objective lens unit;

a second motion-transmitting means coupling said second drive means to said zoom lens unit whereby operation of said second drive means will cause axial movement of said zoom lens unit relative to said objective lens unit and said zoom lens unit;

a space between said outer and inner tubes;

light transmitting means in said spacefor transmitting light to illuminate an object viewed by said objective lens unit;

means attached to said handle assembly for connecting said proximal end of said light transmitting means to a light source;

control means for operating said first and second drive means;

display means responsive to said imaging device output signal for generating a video reproduction of the image passed by said objective lens unit; and

electronic means responsive to said imaging device output signal for causing said display means to generate a video image representative of the position of at least said zoom lens unit or said imaging device.

8. Apparatus according to claim7 wherein said objective lens unit and said zoom lens unit have a common optical axis.

9. Apparatus according to claim7further including light-transmitting means disposed in said space between said inner and outer tubes,wherein said light-transmitting means havinghas a distal end and a proximal end with said distal end terminating at the distal end of said outer tube.

10. Apparatus according to claim7 wherein said first and second drive means comprise first and second reversible electrical motors respectively.

11. Apparatus according to claim10 further including user-operable switch means carried by said handle assembly for selectively operating said first and second electrical motors.

12. Apparatus according to claim7 further comprising means for sensing the extent and direction of movement of said zoom lens unit and said imaging device relative to said objective lens unit and for producing output signals indicative of the extent and direction of said movement, and means for coupling said output signals to said control means for use in controlling the relative positions of said zoom lens unit and said imaging device so that said imaging device is positioned at the focal plane of said zoom lens unit, whereby the image seen by said objective lens and projected by said zoom lens unit is in focus at the image-receiving surface of said imaging device.

13. Apparatus according to claim7 further comprising first and second means for sensing the extent and direction of movement of said zoom lens unit and said imaging device respectively relative to said objective lens unit and for producing first and second output signals respectively indicative of the extent and direction of movement of said zoom lens unit and said imaging device respectively, and means for coupling said output signals to said control means for use in controlling the relative positions of said zoom lens unit and said imaging device so that at each position of said zoom lens unit said imaging device is positioned at the focal plane of said zoom lens unit, whereby the image seen by said objective lens and projected by said zoom lens unit is in focus at the image-receiving surface of said imaging device.

14. An endoscope apparatus comprising:

an inner tube having a distal end and a proximal end; an outer tube surrounding said inner tube;

a solid state imaging device mounted within and movable along said inner tube;

an objective lens unit mounted within and fixed to the distal end of said inner tube;

a zoom lens unit mounted within and movable along said inner tube; said zoom lens unit being disposed between said objective lens unit and said imaging device;

a plurality of light-transmitting fibers disposed between said inner and outer tubes, said fibers extending substantially to the distal end of said inner tube so that light transmitted thereby will illuminate the objective field;

first bi-directional electromechanical means for moving said zoom lens unit along said inner tube toward or away from said objective lens unit, said first electromechanical means comprising a first reversible electrical motor having an output shaft and first gear means coupling said output shaft to said zoom lens unit, whereby energization of said first motor will cause movement of said zoom lens unit along said inner tube according to the mode of energization of said motor; and

second bidirectional electromechanical means for moving said imaging device along said inner tube toward or away from said objective lens unit and said zoom lens unit, said second electromechanical means comprising a second reversible electrical motor having an output shaft and second gear means coupling the output shaft of said second electrical motor to said imaging device, whereby energization of said second motor will cause movement of said imaging device along said inner tube according to the mode of energization of said second motor. ;

a solid state imaging device disposed within said tube and attached to said distal end of said shaft so as to be movable therewith along the axis of said tube, said imaging device having an a light receiving surface for receiving an image transmitted by said objective lens unit and being capable of generating an output signal representative of the image transmitted by said objective lens unit;

display means responsive to said imaging device output signal for generating a video reproduction of the image passed by said objective lens unit; and

means responsive to said imaging device output signal for causing said display means to generate a video image representative of the position of at least said zoom lens unit or said imaging device.

Images