U.S. patent number RE37,356 [Application Number 09/478,231] was granted by the patent office on 2001-09-04 for endoscope with position display for zoom lens unit and imaging device.
This patent grant is currently assigned to Vista Medical Technologies, Inc.. Invention is credited to Koichiro Hori, Herbert A. Thaler.
United States Patent |
RE37,356 |
Hori , et al. |
September 4, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Endoscope with position display for zoom lens unit and imaging
device
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.
Inventors: |
Hori; Koichiro (Framingham,
MA), Thaler; Herbert A. (Framingham, MA) |
Assignee: |
Vista Medical Technologies,
Inc. (Carlsbad, CA)
|
Family
ID: |
26982188 |
Appl.
No.: |
09/478,231 |
Filed: |
January 3, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
319886 |
Oct 7, 1994 |
5582576 |
|
|
Reissue of: |
545927 |
Oct 20, 1995 |
05662584 |
Sep 2, 1997 |
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|
Current U.S.
Class: |
600/103; 348/65;
600/118; 600/167; 600/168 |
Current CPC
Class: |
A61B
1/00188 (20130101); A61B 1/0052 (20130101); A61B
1/05 (20130101); A61B 1/055 (20130101); A61M
25/0136 (20130101); G02B 7/10 (20130101); G02B
23/2438 (20130101); G02B 23/2484 (20130101) |
Current International
Class: |
A61B
1/00 (20060101); A61B 1/002 (20060101); A61B
1/05 (20060101); A61M 25/01 (20060101); A61B
1/005 (20060101); G02B 23/24 (20060101); G02B
7/10 (20060101); A61B 001/045 (); A61B
001/05 () |
Field of
Search: |
;600/103,109,117,118,160,167,168,173 ;348/65,71,76 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leubecker; John P.
Attorney, Agent or Firm: Pandiscio & Pandiscio
Parent Case Text
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.
Claims
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.].
.Iadd.a .Iaddend.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 claim 1 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 claim 1 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 claim 3 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 claim 1 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 claim 5 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.]. .Iadd.for
.Iaddend.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.]. .Iadd.means .Iaddend.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.Iadd.;
light transmitting means in said space .Iaddend.for 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
.Iadd.electronic .Iaddend.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 claim 7 wherein said objective lens unit
and said zoom lens unit have a common optical axis.
9. Apparatus according to claim 7 .[.further including
light-transmitting means disposed in said space between said inner
and outer tubes,.]. .Iadd.wherein .Iaddend.said light-transmitting
means .[.having.]. .Iadd.has .Iaddend.a distal end and a proximal
end with said distal end terminating at the distal end of said
outer tube.
10. Apparatus according to claim 7 wherein said first and second
drive means comprise first and second reversible electrical motors
respectively.
11. Apparatus according to claim 10 further including user-operable
switch means carried by said handle assembly for selectively
operating said first and second electrical motors.
12. Apparatus according to claim 7 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 .Iadd.output
.Iaddend.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 claim 7 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.[...]. .Iadd.;
.Iaddend.
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.].
.Iadd.a .Iaddend.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.
Description
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
along line 4--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 and 11. 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 a handle unit 2 and an elongate tubular
assembly 4. Handle unit 2 comprises a housing 6 with openings
through which four control switch buttons 8A-8D protrude. A fiber
optic cable 10 and an electrical cable 12 are attached to the
proximal (rear) end of housing 6. The elongate tubular assembly 4
comprises a cylindrical outer tube 14 which is open at its distal
(front) end. The proximal end of tube 14 extends into housing 6 and
is secured by a clamp 18 to a first portion of a mounting frame 16
(FIGS. 2 and 8). Housing 6 preferably consists of two or more
mating parts that are releasably secured to one another and frame
16 by suitable screw fasteners (not shown). Mounted within outer
tube 14 is a cylindrical inner tube 20 (FIGS. 4, 5 and 8) which has
its distal (front) end terminating substantially in the same plane
as the corresponding end of the outer tube. The proximal end of
inner tube 20 extends beyond the corresponding end of outer tube 14
and is anchored by a clamp 22 (FIG. 8) to a second portion of frame
16.
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 fibers 28 (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 of fibers 28 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. Fibers 28 project out of the rear end of outer tube 14
and are collected in a protective tubing 30 preferably made of a
material such as a silicone rubber. The rear ends of fibers are
captured in a ferrule 32 that is used to connect it to cable 10.
The rear end surfaces of fibers 28 are optically polished.
Referring now to FIGS. 2, 4, 5 and 10, mounted within and locked to
inner tube 20 is an elongate bushing 34 that has a sleeve bearing
36 located at each end of its central bore or lumen 35 (FIG. 10).
Bearings 36 are made of a material having a low coefficient of
friction. The proximal (rear) end of bushing 34 terminates
substantially flush with the corresponding end of inner tube 20.
The forward end of bushing 34 terminates intermediate the opposite
ends of tube 20 (FIG. 5). As seen in FIG. 4, bushing 34 has a
generally cylindrical outer surface 38 sized so that it makes a
close or tight fit with the inner surface of inner tube 20. That
generally cylindrical outer surface of the bushing is disrupted by
three axially extending grooves 40, 42 and 44. Grooves 40 and 42
are identical in shape and are diametrically opposed to one
another, while groove 44 is somewhat deeper. The purpose of grooves
40, 42 and 44 is described hereinafter.
As seen in FIGS. 1, 2, 3, 5 and 6, mounted within the front end of
and fixed to inner tube 20 is an objective lens unit 48. 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 tube
20 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 within inner tube 20 is a cylindrical video imaging
unit 50 (FIGS. 2, 3, 5, 6). Exact details of imaging device 50 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. Unit 5O 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 a cylindrical housing 52
that is sized to make a close sliding fit in inner tube 20. As seen
in FIGS. 5 and 6, the forward end of housing 52 is provided with a
cylindrical tubular extension 54 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 in groove 44 of bushing 34 and
is coupled to electrical cable 12, whereby the imaging device is
coupled to external electronic circuits as hereinafter
described.
Also mounted within inner tube 20 is a zoom lens unit 60 (FIGS. 2,
3, 5 and 6). 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
unit 60 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 of zoom lens unit 60 are contained
within a cylindrical housing 62 that is sized to make a close
sliding fit in inner tube 20.
Separate means are provided for moving imaging device 50 and zoom
lens unit 60, such means taking the form of electrically powered
drive means and motion transmitting means as shown in FIGS.
2-8.
The motion transmitting means for imaging device 50 comprises a
cylindrical drive rod 66 that extends through bushing 34 and makes
a close sliding fit with its two end sleeve bearings 36. Rod 66 has
a length sufficient for its opposite ends to project from the
corresponding forward and rear ends of bushing 34 when the rod is
in both its distal (forward) and proximal (rear) limit positions
which are described hereinafter. Video imaging unit 50 is attached
to the distal (front) end of rod 66 by a cylindrical coupling
member 67 (FIGS. 3, 5, 6) that is sized to make a close sliding fit
in inner tube 20. Coupling member 67 has a pair of forwardly
extending, diametrically opposed arms 69 (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 with rod 66
when the latter is moved axially relative to inner tube 20.
As seen in FIGS. 3, 7 and 8, the proximal (rear)end of rod 66 is
provided with a series of evenly spaced gear teeth 68, which permit
rod 66 to function as a first gear rack. Gear teeth 68 extend over
a relatively short length of rod 66 and terminate short of the
proximal (rear) end of the rod. The portion of rod 66 that
protrudes from the rear end of bushing 34 extends through and is
slidably mounted by a bushing 70 that is mounted in a portion 72 of
frame 16. Mounted on rod 66 between its proximate end and teeth 68
is a stop member 74 which is positioned to be intercepted by
portion 72 of frame 16 when the rod is moved forward. Stop member
74 and frame portion 72 coact to determine a first (forward) limit
position for rod 66 and imaging device 50. A second (rear) limit
position for rod 66 and imaging device 50 is determined by
engagement of the proximal (rear) end of imaging device housing 52
with the forward end surface of bushing 34.
The drive means for imaging device 50 comprises a reversible
electrical d.c. motor 80 attached to frame 16. Motor 80 is
identified hereinafter as the "focus motor" since in the
invention's automatic mode of operation its function is to move
imaging unit 50 so that the image-receiving surface of its CCD
component is located in the focal plane of zoom lens unit 60. The
output shaft of motor 80 carries a pinion gear 84 that forms part
of a gear system for drive rod 66. Gear 84 meshes with a second
pinion gear 86 affixed to a shaft 88 that is rotatably supported by
portions 90 and 92 (FIG. 7) of frame 16. Shaft 88 in turn carries a
gear 94 (FIG. 7) that meshes with teeth 68 on rod 66, whereby
rotation of shaft 88 by operation of motor 80 will cause linear
motion of shaft 66 and imaging device 50 in a direction determined
by the direction of movement of the output shaft of that motor.
As seen in FIGS. 2 and 4-8, the motion-transmitting means for zoom
lens unit 60 comprises two elongate flat rods 100A and 100B that
are sized to snugly and slidably fit in grooves 40 and 42 of
bushing 34. Grooves 40 and 42 have a depth that assures that rods
100A and 100B will not protrude beyond the periphery of bushing 34.
The front (distal) ends of rods 100A, B are connected to housing 62
of the zoom lens unit. It is to be noted that coupling member 67
has two diametrically opposed grooves 71 (only one is shown in FIG.
6) to slidably accommodate rods 100A and 100B within tube 20.
Grooves 71 are sized so as to make a close sliding fit with rods
100A, B and also so that rods 100A and 100B will not protrude
beyond the periphery of coupling member 67. The rear ends of rods
100A, 100B are attached to a collar 101 that surrounds and makes a
close sliding fit with rod 66. The proximal (rear) ends of rods
100A, B also are provided with a series of evenly spaced gear teeth
102 (FIG. 7).
The drive means for zoom unit 60 comprises a reversible electrical
d.c. motor 106. Both it and motor 80 are attached to frame 16 by a
removable clamp 82. Motor 106 is identified hereinafter as the
"zoom motor". The output shaft of motor 106 carries a pinion gear
108 that meshes with a pinion gear 110 that is mounted on and
secured to a shaft 112. The latter is rotatably mounted to mutually
spaced portions 114, 116 of frame 16. Shaft 112 carries two axially
spaced gears 120A and 120B that mesh with teeth 102 on rods 100A
and 100B respectively, whereby rotation of shaft 112 by operation
of motor 106 will cause linear motion of rods 100A and 100B, and
thereby zoom lens unit 60, lengthwise of inner tube 20 in a
direction determined by the direction of rotation of the output
shaft of the motor. Axial movement of zoom lens unit 60 is limited
by two separate stop means. The forward limit position is
determined by engagement of collar 101 with two stop pins 103
affixed to frame 16. The rear limit position is determined by
engagement of collar 101 with frame portion 72. 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 of focus motor 80 and zoom
motor 106 include position-sensing encoders represented
schematically at 120 and 122 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 of motors 80 and 106 respectively.
Shaft encoders 120 and 122 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 an electronic console 130 to
which the endoscope is coupled. Essentially the console comprises a
light source 134 for the endoscope, an electronic controller
comprising a digital computer 138 (which includes a microprocessor
and associated memory, control and input and output circuits), a
display module 140 that includes a CRT display device (FIG. 20)
whereby the surgeon or other user may monitor the images seen by
the endoscope, an electronic memory device 142, preferably but not
necessarily in the form of an E-prom, that serves as a zoom/focus
lookup table as hereinafter described, and a power supply 132 for
the solid state imaging unit 50, motors 80 and 106, and the
electronic controller. Power supply 132, light source 134, computer
138, display module 140 and E-prom 142 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 that power supply 132 includes a manually operated main
power switch (not shown) which is used to turn the instrument "on"
and "off".
Optical fiber cable 10 is coupled to console 130 so as to be able
to transmit light from light source 134 to light fibers 28, 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 cable 12 is connected at its outer end to power
supply 132 and computer 138; at its inner end cable 12 has certain
of its wires coupled by a connector (not shown) to terminals of the
CCD chip of imaging device 50 and others of its wires connected to
motors 80 and 106 and the control switches associated with buttons
8A-8D.
Referring again to FIG. 13, the switch buttons 8A and 8B form part
of two focus control switches 144A and 144B, while switch buttons
8C and 8D form part of two zoom control switches 144C and 144D.
Preferably, a second like set of foot-operated switches (not
shown), are added in parallel with switches 144A-D so as to give
the surgeon the option of controlling maneuvering of imaging device
50 and zoom lens unit 60 using one of his feet rather than one of
his hands. As explained further hereinafter, operating switch 144A
will energize focus motor 80 so as to cause the imaging device to
move forward toward the distal end of inner tube 20, while
operating switch button 144B will energize focus motor 80 so as to
cause reverse movement of the imaging device. Similarly, operating
switch button 144C will energize motor 106 so as to cause the zoom
lens unit to move forward toward the distal end of inner tube 20,
while operating switch 144D will energize motor 106 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.
Computer 138 is configured by its software program to provide an
object distance counter 160, a focus/CCD position counter 162, and
a zoom position counter 164. The computer is arranged to provide a
control signal to a focus motor drive circuit 166 that preferably
forms part of the controller 130. Switches 144A and 144B are
connected to a focus switch input circuit represented schematically
at 168 that provides an input to object distance counter 160, while
switches 144C and 144D are connected to a zoom switch input circuit
170 that provides control signals to a zoom motor drive circuit
172.
Counters 162 and 164 provide outputs that permit computer 138 to
determine the extent of rotation of the output shafts of motors 80
and 106 from pre-selected positions which are stored in E-prom 142,
whereby at any given time the counts in the counters represent the
exact positions of imaging device 50 and zoom lens unit 60 (in
relation to the pre-selected reference positions along the axis of
tube 20). As illustrated in FIG. 14, the computer is configured so
that (1) the outputs from object distance counter 160 and zoom
position counter 164 are applied to E-prom 142 to obtain a position
data output signal according to those counter outputs and (2) the
output signal obtained from E-prom 142 and the output of focus/CCD
position counter 162 are applied to a comparator or adder 174
(established by computer programming), with the output of the
comparator being an error signal that is supplied to focus motor
drive 166.
FIG. 15 relates to the kind of data that constitutes the zoom/focus
lookup in table E-prom 142. 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 in E-proms 142. 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-prom 142 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-prom
142 are pre-calculated according to the specific parameters of the
lenses embodied in objective lens unit 48 and zoom unit 60, 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 for computer 138. 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 in motors 80 and 106 shifting imaging device 50 and
zoom unit 60 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 of motors 80 and 106 so as to drive imaging device 50 and
zoom unit 60 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 the
corresponding encoders 122 and 124, to stop. Stopping of encoders
122 and 124 causes computer 138 to turn off motors 80 and 106 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)
resets counters 162 and 164 to zero, (2) sets object distance
counter 160 to a predetermined count "n" representing the desired
initial object distance, and (3) actuates zoom motor 106 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 in counter 164 equals a predetermined
"start-up value" (see FIG. 18) accessed by the computer as part of
the reset routine. Then motor 106 is turned off and the computer
actuates focus motor 80 and causes it to move imaging device 50 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 counter 162 as presented to
comparator 174 matches a predetermined start-up value accessed from
the E-prom 142 by the computer as part of the reset routine. At
this points, the counts in counter 162 and 164 are start-up counts,
whereby at any given time the control system can determine new
changed positions of imaging device 50 and zoom lens unit 60 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
the imaging device 50 is moved in a "Down" direction to its
predetermined start-up position, encoder 120 will generate pulses
that are accumulated in counter 162. The output of object distance
counter 160, preset by the computer to the predetermined start-up
value "n" and the output of zoom motor position counter 164, are
applied to E-prom 142 to obtain an output from the zoom/focus
lookup table that has a value representing the desired imaging
device position. The output from E-prom 142 (representing the
desired CCD position) and the output of CCD position counter 162
(representing the actual CCD position) are applied to comparator
174. Depending on whether the actual CCD position represented by
the output of counter 162 is "Up" or "Down" relative to the desired
CCD position represented by the output of E-prom 142, the error
signal produced by comparator 174 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), focus motor 80 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 position counter output 162 will change
and consequently the error signal from comparator 174 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 in comparator 174, 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 result 8f the reset
routine, the image that is displayed by display device 140 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 of buttons 8A and 8B. The resulting operation will
cause counter 160 to be either increased or decreased by clocked
pulses while switch 8A or 8B respectively is depressed. This
changed value in counter 160 is applied to the zoom/focus lookup
table, resulting in a new output value being transferred from the
lookup table to comparator 174. The result is a change in the error
signal output from comparator 174, which in turn is utilized by the
servo control system to further operate motor 80 until the adjusted
CCD position as measured by counter 162 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 utilizes buttons 8C or 8D to operate the zoom
motor so as to zoom up or down with regard to the object being
viewed. As seen in FIG. 17, the zoom motor encoder 122 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-prom 142 is compared with the signal output of counter 162 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 the imaging device 50
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 the buttons 8C and
8D, 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 utilizing buttons 8A and 8B to refocus the image, and
also the option of utilizing buttons 8C and 8D to change the field
of view without again having to utilize the buttons 8A and 8B to
change the position of the imaging device in a direction to restore
or maintain a sharp image for viewing on displaying device 140.
FIG. 20 generally illustrates in diagrammatic form a system for
providing an electronically generated display of the optical image
that is passed by the objective lens unit 48 and zoom lens unit 60
to imaging device 50. An endoscope video signal derived from
imaging device 50 is processed by conventional video circuits
identified generally at 200 to provide signals that are applied to
a TV monitor 204 so as to cause the latter to reproduce as a TV
image the optical image seen by the endoscope's objective lens
unit. The video circuits 200 and the circuits hereinafter described
are preferably embodied in display module 140 (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 of imaging device 50 along the endoscope's optical
axis.
Turning now to FIGS. 21 to 28, 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. When focus control button 8A or 8B
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 the zoom control buttons 8C
and 8D 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 the control buttons 8A-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
video sync stripper circuit 206 which recovers or develops from the
endoscope video signal output of imaging device 50 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 numeral 210 which include inter
alia, a pixel counter 212, a line counter 214, and pixel and line
comparators 216 and 218. 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 the zoom position counter 164 and object distance
counter 160 shown in FIG. 13. The output from counter 164 is the
zoom magnification setting in the form of a digital value while the
output from object distance counter 164 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 the control buttons 8A-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 from zoom position counter 164 is applied to two comparators
224 and 228. Predetermined maximum and minimum reference value
signals are applied as second inputs to comparators 224 and 228
respectively. When the count from zoom position counter 164 equals
the predetermined minimum reference value, comparator 224 will
produce the "Minimum Zoom" signal. A "Maximum Zoom" signal is
generated whenever the zoom count from counter 164 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 to comparators 232 and 234
constituting the output from object distance counter 160 (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 to raster line counter 214, the H-Sync and pixel
clock signals are applied as inputs to pixel counter 212, and the
V-Sync signal and the control button signal are applied as inputs
to a frame counter 238. The line counter 214 counts H-Sync pulses
and is initialized to zero by the V-Sync signals. The pixel counter
212 counts Pixel Clock pules and is initialized to zero by the
H-sync. The frame counter 238 is initialized to zero by pressing
any of the control buttons 8A-8D and counts V-Sync pulses after the
pressed control button is released.
The output of line counter 214 is applied as an input to two
separate line comparators 218A and 218B. Comparator 218A 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. Comparator 218B
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 of frame counter 238, 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 that frame counter 238
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 of pixel counter 212 is applied to three different
comparators 216A, 216B, and 216C. Comparator 216A produces an
"Enable Minimum Display" signal when the pixel counter has a count
between 50 and 56; comparator 216B produces an "Enable Maximum
Display" signal when the pixel count has a count between and
including 142 to 148, and comparator 216C 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 counter 250, two
comparators 252 and 254, and a multiplexer 256. The bar-graph pixel
counter 250 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 to multiplexer 256, with the
latter being controlled by application of the "Enable Focus
Display" signal and the "Enable Zoom Display" signal produced by
line comparators 218A and 218B, respectively. When the line counter
has a value in the range of 32-40, multiplexer 256 is switched by
the "Enable Focus Display" signal so as to pass the predetermined
object distance minimum value signal to bar-graph pixel counter
250, thereby causing the latter to be preset to the minimum object
distance value. When the line count is 232-240, multiplexer 256 is
switched by the "Enable Zoom Display" signal so as to pass the
predetermined zoom initial minimum value signal to counter 250 so
as to preset the counter to that minimum value.
Comparators 252 and 254 also receive the outputs of object distance
counter 160 and zoom position counter 164. When the output from
object distance counter 160 matches the output of bar-graph pixel
counter 250, comparator 252 will produce the "Enable Focus
Indicator Display" signal. The "Enable Zoom Indicator Display"
signal is generated when the signal from zoom counter 164 matches
the value of the output of bar-graph pixel counter 250.
As shown in FIGS. 27A to 27F, 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 monitor 204 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, AND gate 260
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 AND gate 264 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 AND gate 266 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 with gate 268 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 AND gates 270 and 272 of FIGS. 27E and 27F are similar except
that the "Enable Maximum Display", "Enable Zoom Display" and
"Maximum Zoom" signals are used to cause gate 270 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 cause gate 272 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 of gate
272 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. The rectangle 276 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 relatively large rectangle 280A represents the minimum end
limit for the object distance (focus) parameter, while the smaller
rectangle 282 represents the instantaneous bar-graph value of
object distance parameter. The minimum focus limit marker 280A
appears only when the object distance value represented by marker
282 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 1/4
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, the rectangle 282 moves
to the right on the TV display to indicate a larger object distance
value. As the rectangle 282 moves to the right, the larger end
limit rectangular marker 280A will disappear. When the object
distance value represented by rectangular marker 282 approaches its
other (maximum) end limit, another large rectangle (shown in
phantom at 280B) similar to rectangle 280A will appear at the right
hand end of the image window 276.
The relatively large and relatively small rectangular markers 286A
and 288 in FIG. 28 represent the maximum zoom position limit and
the instantaneous zoom positions respectively. The marker 288 moves
to the left as the zoom lens unit is moved forwardly in the
endoscope. The larger end limit marker 286A appears only when
marker 288 approaches the maximum end limit for the zoom lens unit,
and disappears when marker 288 moves away from that markers end
limit. Another minimum end limit marker 286B 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.
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