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Description  |
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This invention relates to an endoscope for processing color information and
providing a read-out signal that is fully compatible with any standard
format television equipment.
In U.S. Pat. No. 4,074,306, there is disclosed an endoscope system for
producing a full color image of the region scanned by the viewing head of
the system. In this prior art device, the image information contained in
the viewing region of the system is separated into the three primary
colors of red, green and blue, and the images then sequentially laid down,
one on top of the other, on a Braun tube to recreate the original full
color image. The three primary color images are created by either
mechanically filtering the illuminating light brought into the cavity
using a single light source and a rotating filter disc or by breaking down
a reflected light image of the viewing region using a series of dichroic
mirrors.
Although the prior art device performs well, it nevertheless requires
special equipment to sequentially process the three independent read-out
signals. Mechanically driven filter discs also can present timing and
balancing problems which, under certain conditions, can be troublesome.
Because the disc mounted filters move through an arcuate path of travel, a
sharp, well defined edge between images, which is essential in a high
speed system, cannot be obtained. Lastly, the use of dichroic mirrors and
the like in the viewing head of the system increases the size of the head
and thus makes it difficult to insert into relatively small body cavities
or openings thereby limiting the usefulness of the instrument.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to improve endoscopes
for providing color pictures of a remote viewing region.
It is another object of the present invention to provide an endoscope
system that is capable of utilizing standard format video equipment for
storing, displaying or otherwise processing color image information. A
still further object of the present invention is to improve the
illumination system used in an endoscope for producing three primary color
light images of the visual information found in the viewing region of the
instrument.
Another object of the invention is to eliminate the need for special
read-out equipment in a color endoscope system.
Yet another object of the present invention is to simplify the component
parts used in an endoscope system for providing a full color picture of
the visual information contained in the object plane of the system.
A further object of the present invention is to produce an enlarged, high
resolution, picture of the scene found in the viewing plane of an
endoscope using standard video equipment.
These and other objects of the present invention are attained by means of
an endoscope having a compact viewing head which is easily insertable into
a relatively small body opening and an external electronics section that
is arranged to receive color image information from the viewing head and
provide a read-out signal that is fully compatible with standard format
television equipment. Three separate light images, each containing data
relating to an individual primary color, are generated by electrically
strobbing a series of lamps having rapid response times.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of these and other objects of the present
invention, reference is had to the following detailed description of the
invention to be read in conjunction with the following drawings, wherein:
FIG. 1 is a block diagram of an endoscope system according to a first
embodiment of the invention wherein a full frame interlaced picture is
produced upon a standard television viewing screen;
FIG. 2 is a block diagram of a simplified version of the system shown in
FIG. 1;
FIG. 3 is a partial view in section showing the illumination system
utilized in the present invention;
FIG. 4 is a view taken along lines 4--4 in FIG. 3 showing the end view
configuration of the viewing head employed in the present invention; and
FIG. 5 is a block diagram of an endoscope according to another embodiment
of the invention, and
FIG. 6 is a block diagram illustrating a still further embodiment of the
invention.
DESCRIPTION OF THE INVENTION
As shown in FIG. 1 of the accompanying drawings, the endoscope of the
present invention, which is generally referenced 10, is made up of a
viewing head 11, which is adapted for insertion into a relatively small
cavity or opening, and an electrical section 32 that is arranged to
receive visual data signals from the viewing head and convert the data
into an output signal that is fully compatible with standard format
television equipment for storing, displaying or transmitting the signal
information. This type of equipment can include but is not limited to
video tape recorders, television monitors, television receivers and the
like.
The present system also includes a light handling section 12 containing
three individual strobe lamps 13-15 that are sequenced in a programmed
firing order by means of a strobe drive 17. Positioned at the light
emitting surface of the lamps are optical elements 18-20 which serve to
filter the emitted light and to focus the light upon the light entrance
face of a fiber optic bundle. Each lamp is a high intensity unit capable
of producing white light without generating harmful amounts of infrared.
The lamps can be adjusted over a relatively wide operating range without
sacrificing color temperature. Each lamp, when pulsed on or off, exhibits
a rise or fall time within the 10 to 100 microsecond range.
In practice, each of the optical elements 18-20 is specially prepared to
transmit only light relating to one selected primary color while blocking
all other light. The present illumination system is programmed to strobe
light into a light entrance face of the fiber bundle in a red, green and
blue sequence although any desired firing order may be selected.
As seen in FIG. 3, the proximal end of the fiber bundle 22 is trifurcated
with each arm being positioned adjacent to one of the optical elements
18-20. The light entrance face of each arm is generally perpendicular to
the optical centerline of the adjacent element and lies about within the
focal place of the element. Accordingly, a preponderance of the light
passing through each element is caused to enter the bundle and is
channelled along the flexible bundle into the remote viewing head 11.
The bundle is bifurcated at the distal end thereof to provide for better
space utilization in the viewing head and to reduce the shadowing effect
normally produced by a single bundle. The three color carrying sections of
the bundle are further randomized at the distal end to produce homogeneous
mixing of colors in the viewing region and thus provide for uniform
illumination during each strobed imaging cycle. The illumination released
from the bundle is directed into the object of viewing plane of the system
by means of a lens or lens system 26. The lens and the fiber bundle may be
either physically or optically adjusted, or both, to produce optimum
illumination within the object plane.
Located immediately below the light carrying fiber bundle is an objective
or image forming lens 28. The objective is arranged to focus an image of
the scene contained in the object plane thereof upon the light receiving
surface 29 of a self-scanning solid state imaging device such as charge
coupled device (CCD) 30 located in the image plane of the objective.
Although a simple lens system is depicted in the drawings, it should be
clear to one skilled in the art that a more complex optical system can be
herein employed without departing from the teachings of the present
invention. Preferably, the objective lens system is provided with a wide
angle viewing accommodation wherein the view angle 0 is about 85.degree..
As disclosed in further detail in the February 1974 issue of Scientific
American, a CCD imager contains a number of photosensitive picture
elements, generally referred to as "pixels", which are perpendicularly
aligned with reference to the optical centerline of the system to form a
generally rectangular grid pattern. In operation, light energy falling
upon the CCD receiving surface causes electrons contained within each
pixel region to accumulate or gather into charge packets. After a timed
interval the charge in each packet is applied to an electrode associated
with the pixel thereby providing an electrical read-out of the visual
image information recorded upon the receiving surface. The data stored in
the imager is then clocked out of the element in a line by line sequence
similar to that employed in a serial flow shift register. The imager
employed in the present invention has a driver-amplifier 33 (FIG. 3) that
is operatively associated therewith and which serves both as a means for
driving the CCD components and for providing immediate preamplification of
the read-out data. Preamplification eliminates unwanted generation of
noise or crosstalk in the lines and the driver reduces the number of
electrical leads needed in read-out line 31 connecting the imager with
external electrical package 32.
With further reference to FIG. 4, the viewing head includes a pair of
illumination windows 34--34 and a single image viewing window 35. As
noted, the bifurcated distal end of fiber bundle 22 provides added space
within the viewing head whereby components, such as the biopsy device 36
illustrated in FIG. 4, may be conveniently located therein. Means to wash
fluids and the like from the windows may also be located in this region
along with, or in place of, the biopsy device.
Referring now more specifically to FIG. 1, the electrical section 32 of the
system is arranged to accept the visual information signal from the solid
state CCD imager and place the information in a format that is compatible
with standard video processing equipment. As is typical in most, if not
all, standard format television equipment, each picture frame is made up
of two interlaced fields of data which combine to provide a faithful
rendition of the region viewed. Each field further contains a preselected
number of horizontal data lines which are laid down on the viewing screen
within a prescribed period of time. Although the number of data lines and
the duration of the field periods, may vary, the operation of the video
systems remain basically the same.
For explanatory purposes, the apparatus of the present invention will be
described in reference to a television format in which each field contains
244 horizontal lines of data which are presented in 1/60 of a second.
Accordingly, each frame will contain 488 lines of data and take 1/30 of a
second to complete. To accommodate this format, the CCD imager is provided
with a 488.times.358 pixel grid pattern. The horizontal number of 358
pixels can also be varied depending upon the bandwidth of the receiver and
the degree of resolution desired.
In the imaging system shown in FIG. 1, the first field period of 1/60 of a
second is utilized to load visual color information supplied by the CCD
into three memory units or registers 40, 41 and 42. The three memories are
located in a first memory bank 43. In operation, each lamp in the
illumination system is triggered once during each field period through
means of a strobe drive 17 acting in response to a timing signal from the
clock of master timing circuit 45. The master timer may consist of a
conventional synchronization generator which is used independently or with
logic gates to provide the necessary switching functions that are required
in the practice of the invention. Typically, each lamp is flashed on and
off at 1/180 of a second interval whereby the region in the object plane
of the viewing lens is illuminated in an ordered red, green, blue sequence
during each field period.
During the first red imaging interval, the CCD imager accepts red visual
image information and converts it to an electrical output data signal that
is applied to the preamplification section of the driver amplifier 33 and
then passed to video amplifier 38. The interval from illumination to
read-out takes 1/180 of a second. At the start of the red imaging cycle,
the timing circuit has also conditioned analog switches 46 and 47 to be
positioned so that the data signal from the amplifier is clocked into a
first memory unit 40. In practice, each unit is preferably an analog CCD
chip, however, any suitable shift register for storing this type of data
may be used. As will become apparant from the disclosure below, each CCD
memory in this particular embodiment is required to store data only during
one of the two fields making up a frame and therefore the memory unit
utilizes a simplified 244.times.358 pixel grid arrangement.
On the following green imaging cycle, the CCD imager is clear of data and
is placed in a condition to accept green color information. Here again,
the output data signal from the imager is amplified and shifted in a line
by line sequence into the first memory 40 in the bank. This action in turn
causes the red image data contained in memory 40 to pass serially into
memory 41. Similarly on the next blue imaging cycle, blue color
information that is generated is shifted into memory 40 whereupon red data
passes serially into memory 42 and green data passes into memory 41. This
completes the first or odd field period.
At the end of the first field, the master timing circuit causes analog
switches 46-48 and 57,57 to be repositioned whereby color information
stored in memories 40-42 is simultaneously clocked into the video
processor at video-speed. The parallel flow of information is synchronized
with the 244 line presentation of the second field by means of the master
timer. As this data is being clocked into the video equipment, new data is
being fed into a second bank of memories 44 from the CCD imager.
In the video processor 50, the initial three color data is corrected and
placed in a form that is acceptable by standard television equipment. As
is well known in the art, the processor includes a transmitter matrix for
combining the three color signals into composite luminance and chrominance
signals that are used in the receiver to control the various picture
functions. To obtain instantaneous viewing of the data, the signal is
modulated at unit 51 and passed directly to a T.V. receiver 52 for
providing a visual presentation thereof. The modulator can be one of many
such commercially available radio frequency units that are fully
compatible with standard NTSC television matrixes and receivers.
During the second or even field period, the lamps are again strobbed in the
noted sequence and the primary color information shifted serially into
registers 55, 54, 53 as noted above in a red, green and blue sequence.
Upon receipt of the new data, the analog switches are again repositioned
through means of timing circuit 45. The stored data is passed in parallel
flow into the processor 50. A second field of color information is then
processed and is interlaced within the first field to create a high
resolution color rendition of the viewing region which can be presented
upon the screen of receiver 52, while an odd field is being stored in the
memory bank 44.
FIG. 2 illustrates a simplified arrangement of the invention wherein the
number of memory units needed to create a color picture is reduced. The
video processing and viewing equipment 50-52 again is standard format
equipment and the illumination system and viewing head remain the same
with the like components being referenced with like numerals. Here again,
a full screen presentation is furnished. However, because of the reduction
in memory units, one field in every frame must be blanked. This causes a
reduction in the resolution of the picture but enables a simpler
244.times.179 pixel format to be employed in regard to the CCD imager.
Correspondingly, only two memory units 60 and 61 are required and these
memories can be greatly simplified and thus more economical to build.
At the beginning of the first field, analog switches 63, 64 are positioned
as shown so that red and green image information clocked out of the CCD
imager is shifted serially into memories 61 and 60 respectively. Through
means of the master timer 62, each color signal is clocked out of the
imager during a 1/120 of a second interval. At the start of the next
field, the read-out speed of the CCD imager is changed via the master
timer. Switches 63 and 64 are also repositioned so as to feed blue data
stored in the imager 30, along with the data stored in the memories 60,61,
in parallel flow relationship into the processor 50, through the modulator
51 and finally present the data upon TV receiver 52 as explained above.
As can be seen, in this simplified embodiment of the invention, only one
field of each frame is employed to generate a visual display at the TV
screen. The second field of the frame, of course, is blanked or grounded
out during the period when new data is being stored in the memory units.
As a result, the resolution of the picture may be slightly affected due to
the lack of interlacing. However, the detail and quality of the picture is
more than satisfactory to enable the instrument to be used for its
intended purpose.
The circuitry required to produce the color picture is simplified and the
cost of the imager and memory units considerably reduced through the use
of the 244 line arrangement.
Turning now to FIG. 5 there is shown in block diagram form a further
embodiment of the invention also utilizing the previously described
viewing head and illumination system. Here again, like numerals are used
to depict similar or like parts. In this embodiment the output signal of
the CCD imager is applied to an analog-to-digital (A-D) converter 65 whose
digital output is transmitted to a computer section generally referenced
67. In the A-D converter, color image information clocked out of the CCD
imager is placed in six bit digital form. It has been found that a six bit
output will contain sufficient information whereby a high resolution
picture signal is provided to the video equipment. It should be clear,
however, that more or less bits of data can be similarly employed without
departing from the teachings of the present invention. The A-D converter
output is applied to multiplexer 71 and the data is multiplexed onto one
of six output data lines in response to a signal from master timer 73.
During the first field, three color data is loaded into a first bank of
memory units 74 while during the second field three color data is loaded
into a second bank 75, also containing three memory units.
As noted, the CCD imager will preferably have a 488.times.358 pixel grid
arrangement for delivering a full screen interlaced picture at the
receiver 52. The lamps 13-15 are thus strobbed at 1/180 of a second
intervals to provide one full color field every 1/60 of a second. After
the color signals are converted to digital form, they are multiplexed into
the two banks of memories 74,75, each of which contains a red, green and
blue image retention section.
During the first field, the information stored in bank 74 is passed to
output multiplexer 76 and then on to three digital-to-analog converters
77, 78 and 79. In response to a signal from the master timer, the three
color signals are simultaneously passed from the D-A converter on to the
video processor 50, modulator 51, and video receiver 52 at video speed.
During the first field, new color data is being loaded into the red, green
and blue memories of the lower bank 75. At the start of the second field
the function of the memories is reversed, thereby enabling the system to
deliver color data to the video equipment during each field of a frame.
As is well known in the art, an endoscope is typically employed to view the
inside of body cavities. It is therefore essential that the viewing head,
that is, the portion of the device that is inserted into the body cavity
be as small as possible to provide for the safety and the comfort of the
subject. As should be apparent from the instant disclosure, because the
present device utilizes a single CCD imager in the viewing head, its size
can be minimized without sacrificing performance. It should be further
noted that the size of the CCD imager can be further reduced by changing
the pixel grid arrangement to something less than the 488 line format used
in standard TV equipment.
For example, a system using a 244.times.134 grid pattern may be employed to
provide interlacing as disclosed in the inventive embodiment of FIG. 1. In
this case, the total area of the picture on the screen is reduced.
Although the picture is slightly reduced in size the resolution of the
picture, however, is relatively unaffected. Furthermore, in this reduced
picture format, the unused portion of the screen may be electronically
imaged to present added information relating to the subject being viewed
or any other related data that might be desired.
Because the present apparatus is compatible with all standard video
equipment, the subject matter being viewed may be video taped for storage
and future reference. This can be simply accomplished by applying the
output of modulator 51 to any standard video processor 80 as shown in FIG.
5. Similarly, as shown in FIG. 2, raw data taken from the video processor
can be sent directly to a standard video-monitor 59 for viewing, thus
eliminating the need for video units 51 and 52.
Turning now to FIG. 6, there is shown another embodiment of the invention
wherein color data that is stored in a series of memories is continually
fed to the video equipment at video speed to provide a full frame, fully
interlaced color signal suitable for viewing, tape storage or the like. In
this embodiment, however, each primary color signal that is stored in one
of the memory units is periodically updated with the up-grading being
accomplished at a speed that is considerably slower than video speed. This
result is herein achieved using four memory units 85-88. Three of the
units feed data to the video equipment while the fourth is being upgraded.
Here again, the remote viewing region is illuminated by light of a primary
color through means of the three lamp system as previously described. The
light image is used to expose the CCD 30 and an electrical read-out signal
indicative thereof is clocked out of the device in a line-by-line
sequence. As shown in FIG. 6, the read-out data from the imager can be
selectively applied to one of the four memory units. In operation, each of
the memories is wired into the system in the same manner. The input signal
data is passed from the amplifier 38 into each memory via electrically
operated switch S-1. A portion of the output signal is divided out,
amplified, and then fed back to the input of the memory via line 91 and
electrically operated switch S-3.
In practice, red, green and blue data from the CCD imager is sequentially
stored in three of the memories, as for example, memories 86, 87 and 88,
by sequentially cycling the associated input switches S-1 in response to a
preprogrammed signal from master timer 93. With the color information
stored in each unit, the S-2 and S-3 switches associated therewith are
simultaneously closed at the beginning of a frame and the stored
information is clocked out of the units in parallel flow at video speed.
As the information is being fed out of each unit in a line-by-line
sequence, the old data is also being restored in the unit through means of
the feedback network. By this means, color image data is continually
provided to the multiplexer during one field of each frame while, at the
same time, the memories are isolated from the CCD imager.
While data concerning the three primary colors is being forwarded to the
multiplexer at video speed, updated data concerning one of the primary
colors can be passed from the imager into the fourth memory 85 at a
relatively slower speed. During the upgrading period switch S-1 of unit 85
is closed while S-2 and S-3 are opened. Again positioning of the switches
is accomplished through means of the timing circuit 93. When memory 85 has
been supplied with the desired 244 lines of updated information, the
memory containing old data relating to the same primary color is taken off
the line by opening associated switches S-2 and S-3 in an ordered timed
sequence. Initially S-3 is opened while S-2 is held closed to permit the
stored data to be cleared into the multiplexer 90. Once the old data is
cleared, switches S-2 and S-3 associated with the upgraded memory are
simultaneously closed in timed relationship with the beginning of the next
field period whereby the new data is forwarded from the upgraded memory in
parallel flow with the remaining stored data into the multiplexer 90.
Switch S-1 of the upgraded memory, at this time, is now opened while that
associated with the cleared memory is closed.
The memory that has been cleared is now in a condition to receive new or
updated data relating to a second primary color whereby the above noted
sequence of events is repeated. Each color is thus sequentially updated to
continually upgrade the picture information.
The three color data passed into multiplexer 90 is processed, as is well
known in the art, and multiplexed out by means of three output data lines.
The multiplexed signal is passed on to video processor 50, modulator 51
and viewer 52.
While this invention has been explained with reference to the structure
disclosed herein, it is not confined to the details as set forth and this
application is intended to cover any modifications or changes as may come
within the scope of the following claims.
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