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This invention relates to an endoscope for visualizing the interior of a
hollow organ or of a cavity in constitutional parts of a machine and
simultaneously visualizing a color picture image by a number of persons.
In the endoscope, heretofore it has been the common practive to transmit a
picture image of the hollow organ or cavity to be visualized (hereinafter
will be called as hollow cavity) through an image guide to the exterior of
the hollow cavity and obtain television picture signals by means of a
vidicon tube, etc., which signals are subsequently displayed on a Braun
tube for the purpose of simultaneously visualizing the color picture image
by a number of persons. In addition, in the case of forming an easily
discernible picture image by a picture image treatment such as a
differentiation treatment or a filtration treatment so as to make the
image contour distinguishable, use has also been made of a vidicon tube,
etc. so as to transform the picture image into television picture signals
and then the above mentioned treatment has been effected. The use of the
vidicon tube provides the disadvantage that the endoscope becomes large in
size and complex in construction and hence expensive and that various
kinds of adjustments thereof are troublesome in operation. This
disadvantage becomes more important if it is desired to display a color
picture image.
In addition, the endoscope makes use of a rotary tricolor filter arranged
between a light transfer body and a light source. The presence of the
tricolor filter requires a mechanism for rotating the tricolor filter and
a circuit for changing a signal to be supplied to a Braun tube into a
signal synchronized with the rotation of the tricolor filter, and as a
result, it is not always possible to provide an endoscope which is simple
in construction and small in size. Moreover, that part of the endoscope
which is inserted into the hollow cavity is provided therein with a bundle
of lead wires connected to both the illumination light transfer body and a
self-scanning type solid state image pick-up device. As a result, it is an
inevitable consequence that part of the endoscope which is inserted into
the hollow cavity becomes large in size.
The prior art endoscope has another disadvantage that if a light
decomposition optical system or the solid state image pick-up device
becomes damaged, it is troublesome to remove the solid state image pick-up
device due to the presences of a number of long lead wires and mount the
light decomposition optical system and the solid state image pick-up
device in that part of the endoscope which is inserted into the hollow
cavity.
In addition, in the endoscope, one solid state image pick-up device is
supplied with a number of driving signals for the purpose of scanning an
image of the object to be visualized, which is formed on the light
receiving surface of the solid state image pick-up device, and hence
picking up a picture image signal. In this case, there is a risk of the
picture image being mixed with the driving signals. In order to prevent
the picture image from being mixed with the driving signals, the endoscope
is designed such that a compensation signal depending upon the driving
signals is derived from the solid state image pick-up device and both the
compensation signal and the picture signal are supplied through a bundle
of lead wires to respective differential amplifiers arranged exterior of
the hollow cavity, thereby compensating noises produced due to the driving
signals and mixed into the picture signal and deriving a normal picture
signal. In this case, if the bundle of lead wires for supplying the
driving compensation signal and the picture signal to the respective
differential amplifiers are formed by merely assembling together, noises
produced due to the presence of devices arranged outside the hollow cavity
or noises produced due to the driving compensation signals supplied to
another solid state image pick-up device which is used in the case of
displaying a color picture image are mixed into either one of the signal
wires, and as a result, it is not always possible to derive a normal
picture image. The noises are also displayed on the picture surface on the
Braun tube, thereby degrading the quality of the displayed picture. In
addition, the longer that part of the endoscope which is inserted into the
hollow cavity is the more the mixing of various kinds of noises, thus
resulting in a more significant deterioration of the quality of the
displayed picture.
An object of the invention is to provide an endoscope which can display a
color picture image of an object to be visualized without using a vidicon
tube, which is small in size, simple in construction, easily operable, and
less expensive.
Another object of the invention is to provide an endoscope which makes use
of a light decomposing optical system composed of a pentaprism and a light
transmission block and which can decompose a light reflected by an object
to be visualized into three color signals in that part of the endoscope
which is inserted into a hollow cavity.
A further object of the invention is to provide an endoscope which makes
use of a delay circuit for delaying one of outputs from a solid state
image pick-up device for one horizontal scanning period and a memory for
reversing another output from another solid state image pick-up device
during one horizontal scanning period.
A still further object of the invention is to provide an endoscope wich
makes use of one package at least light output portion of which is
transparent and which encloses therein a plurality of solid state light
emitting chips adapted to emit blue, green and red lights, respectively,
when supplied with electric current.
Another object of the invention is to provide an endoscope which makes use
of one package at least light outlet portion of which is transparent and
encloses therein a plurality of solid state light emitting chips adapted
to emit blue, green and red lights, respectively, when supplied with
electric current and a circuit for driving these light emitting chips.
Another object of the invention is to provide an endoscope comprising a
light decomposition optical system composed of a light transmission prism
and a light transmission block and including a number of signal transfer
wires and connector contacts deposited on the light decomposition optical
system and a receptacle including a number of contacts deposited therein
and detachably connected to the connector contacts.
A further object of the invention is to provide an endoscope for
visualizing the interior of a hollow cavity, which comprises a solid state
image pick-up device mounted in that part of the endoscope which is
inserted into the hollow cavity and a picture image signal wire and a
driving compensation signal wire twisted together along their overall
length, and which can derive a normal picture image signal without
containing any external noise.
The invention will now be described in greater detail with reference to the
accompanying drawings, wherein:
FIG. 1 is a partial sectional view showing one embodiment of that part of
an endoscope according to the invention which is inserted into a hollow
cavity and can display a color picture image;
FIG. 2 is a block diagram for illustrating one embodiment of a circuit
arranged outside the part shown in FIG. 1 of the endoscope according to
the invention;
FIGS. 3 and 4 diagrammatically illustrate a relation between a tricolor
filter and a light inlet end surface of a light transfer conductor shown
in FIG. 2;
FIG. 5 is a partial sectional view showing a modified embodiment of the
part shown in FIG. 1;
FIG. 6 is a block diagram for illustrating another embodiment of a circuit
arranged outside the parts shown in FIGS. 1 and 5 of the endoscope
according to the invention;
FIG. 7 is a block diagram for illustrating a further embodiment of a
circuit arranged outside the parts shown in FIGS. 1 and 5 of the endoscope
according to the invention;
FIG. 8 is a plan view showing one embodiment of a tricolor filter used for
the circuits shown in FIGS. 2, 6 and 7;
FIG. 9 is a graph showing a signal wave for illustrating an operation for
detecting color change-over signals;
FIG. 10 is a sectional view showing one embodiment of a light decomposition
optical system adapted to be enclosed in the parts shown in FIGS. 1 and 5;
FIG. 11 diagrammatically illustrates the minimum dimensions of the light
decomposition optical system shown in FIG. 10;
FIG. 12 is a partial sectional view showing a further embodiment of that
part of an endoscope according to the invention which is inserted into a
hollow cavity and comprises a light decomposition optical system shown in
FIG. 10;
FIG. 13 is a partial sectional view showing a modified embodiment of the
part shown in FIG. 12;
FIG. 14 is a block diagram for illustrating one embodiment of a circuit
arranged outside the parts shown in FIGS. 12 and 13 of the endoscope
according to the invention;
FIG. 15 is a block diagram for illustrating a modified embodiment of the
circuit shown in FIG. 14;
FIG. 16 is a sectional view showing another embodiment of a light
decomposition optical system adapted to be enclosed in the part shown in
FIG. 1;
FIG. 17 is a sectional view showing a further embodiment of a light
decomposition optical system adapted to be enclosed in the part shown in
FIG. 5;
FIG. 18 diagrammatically illustrates the minimum dimensions of the light
decomposition optical system shown in FIG. 16;
FIG. 19 is a partial sectional view showing a still further embodiment of
that part of an endoscope according to the invention which is inserted
into a hollow cavity and comprises a light decomposition optical system
shown in FIG. 16;
FIG. 20 is a partial sectional view showing a modified embodiment of the
part shown in FIG. 19, which comprises a light decomposition optical
system shown in FIG. 17;
FIG. 21 is a block diagram for illustrating one embodiment of a circuit
arranged outside the parts shown in FIGS. 19 and 20 of the endoscope
according to the invention;
FIG. 22 is a front elevational view showing one embodiment of a solid state
light emitting device according to the invention;
FIG. 23 is its plan view;
FIG. 24 is a block diagram for illustrating one embodiment of an endoscope
according to the invention which makes use of the solid state light
emitting device shown in FIGS. 22 and 23;
FIG. 25 is a front elevational view showing another embodiment of the solid
state light emitting device according to the invention;
FIG. 26 is its plan view;
FIG. 27 is a circuit diagram showing one embodiment of circuit elements
enclosed in the package shown in FIGS. 25 and 26;
FIG. 28 is a circuit diagram showing another embodiment of circuit elements
enclosed in the package shown in FIGS. 25 and 26;
FIG. 29 is a block diagram for illustrating one embodiment of an endoscope
according to the invention which makes use of the solid state light
emitting device shown in FIGS. 25 and 26 and the circuit elements shown in
FIG. 27 or FIG. 28;
FIG. 30 is a fragmentary perspective view showing the light decomposition
optical system shown in FIG. 10 and provided at its side surfaces with
contacts connecting wires;
FIG. 31 is a perspective view showing one embodiment of a receptacle
detachably engageable with the light decomposition optical system shown in
FIG. 30;
FIG. 32 is a block diagram for illustrating the circuit shown in FIG. 14
arranged outside the part shown in FIG. 12 which makes use of the light
decomposition optical system shown in FIGS. 30 and 31;
FIG. 33 is a partial sectional view showing that part of the endoscope
according to the invention which is inserted into a hollow cavity shown in
FIG. 12 and comprises pairs of picture image signal wires and driving
compensation signal wires, each pair of picture image signal wire and
driving compensation signal wire being twisted together along their
overall length; and
FIGS. 34A, 34B and 34C are graphs showing a signal waves which illustrate
operation of the part of the endoscope shown in FIG. 33.
Referring now to FIG. 1 showing one embodiment of that part of the
endoscope according to the invention which is inserted into a hollow
cavity, the present embodiment of the part shown in FIG. 1 is of a direct
view type. A light emitted from a light source 21 (FIG. 2) is transmitted
through a light transfer body 8 and a glass window 7 onto an object to be
visualized. A light reflected by the object to be visualized is
transmitted through a glass window 2 and a lens 4 onto a light receiving
surface of a self-scanning type solid state image pick-up device 5 to form
an image of the object to be visualized onto the light receiving surface.
The solid state image pick-up device 5 is composed of a number of
photosensitive elements arranged on a flat plane. The output signal
delivered from the solid state image pick-up device 5 is transmitted
through a bundle of lead wires 6 to the outside of the part. The bundle of
lead wires 6 is inclusive of a lead wire for supplying a clock signal from
an oscillation circuit 27 (FIG. 2) to the solid state image pick-up device
5, the clock signal serving to operate the solid state image pick-up
device 5. Both the light transfer body 8 and the bundle of lead wires 6
are inserted into a sheath 14. In addition, the lens 4 and the solid state
image pick-up device 5 are arranged in a casing 15 enclosed in the sheath
14.
In FIG. 2 is shown one embodiment of a circuit arranged outside the part
shown in FIG. 1. To a light inlet end surface 8a of the light transfer
body 8 projected from the rear end of the sheath 14 is opposed the light
source 21. Between the light source 21 and the end surface 8a are arranged
a tricolor filter 22 and a half reflecting mirror 23. The tricolor filter
22 is rotated at a given speed by means of a motor 20.
The tricolor filter 22 is equally divided into three segments 40, 41 and 42
as shown in FIG. 3, the segment 40 transmitting a blue light having a
center wave length of 450 nm, the segment 41 transmitting a green light
having a center wave length of 540 nm and the segment 42 transmitting a
red color having a center wave length of 600 nm. As a result, a liht
incident on the light inlet end surface 8a of the light transfer body 8 is
changed in succession in the order of blue, green and red light in a given
period.
In this case, the light inlet end surface 8a may be made circular in
section as shown by dotted lines in FIG. 3 or slit-shape in section as
shown by dotted lines 8a' in FIG. 4. When the tricolor filter 22 is
rotated at a constant speed, it is desirous to make the light inlet end
surface 8a of the light transfer body 8 slit-shape as shown in FIG. 4 by
taking the changing over time at the boundary between the two color lights
into consideration. But, in the case of manufacturing the end surface 8a
of the light transfer body 8, it is easier to make the end surface 8a
circular in section as shown in FIG. 3. In the case of making the light
inlet surface 8a of the light transfer body 8 circular in section, in
order to make the change-over time at each color light short, it is
possible to make the diameter of the tricolor filter 22 large and arrange
the end surface 8a of the light transfer body 8 at a position near the
outer periphery of the tricolor filter 22.
The light reflected by the half reflecting mirror 23 is incident on a light
receiving element 24 whose output is supplied to a color change-over
signal generation circuit 25. If the light receiving element 24 is
composed of a phototransistor or a photdiode, a ratio among the levels of
output from the tricolor filter 22 with respect to the blue, green and red
lights becomes 1:4:6. The color change-over signal generation circuit 25
consists of a current amplifier and a level detection circuit and serves
to convert the output current signal from the light receiving element 24
into a voltage signal and form timing signals of the blue, green and red
lights, respectively, by means of the level detection circuit. In
addition, the output from the current amplifier of the color change-over
signal generation circuit 25 is differentiated so as to align the level
thereof to form a trigger signal which is then supplied to an oscillation
circuit 27. A picture image signal delivered from the solid state image
pick-up device 5 through the bundle of lead wires 6 to the outside of the
sheath 14 is supplied through an amplifier 25 to a signal change-over
circuit 28 which is then operated to supply the picture image signal to
respective output terminals 28B, 28G and 28R in synchronism with the kinds
of color of the light incident on the light transfer body 8.
The signal change-over circuit 28 makes use of a high speed operation
switch such as a semiconductor analog switch, etc. The oscillation circuit
27 receives the trigger signal from the color change-over signal
generation circuit 25 and supplies a scanning signal to the image pick-up
device 5 and synchronizing signals to a horizontal deflection circuit 35
and a vertical deflection circuit 36, respectively. The horizontal
deflection circuit 35 is composed of an output amplifier for sweeping each
of blue, green and red lights in the horizontal direction and the vertical
deflection circuit 36 is composed of an output amplifier for sweeping each
of blue, green and red lights in the vertical direction.
The outputs from the output terminals 28B, 28G and 28R of the signal
change-over circuit 28 are supplied to blue, green and red amplifiers 32,
33, 34, respectively, which amplify the outputs from the output terminals
28B, 28G and 28R to voltages which are sufficient to operate blue, green
and red grids of a Braun tube 37.
In the case of displaying a color picture image with the aid of, for
example, a field sequential system, the tricolor filter 22 is rotated such
that the blue, green and red light portions of the tricolor filter 22 are
changed over with a field period. The color change-over signal generation
circuit 25 serves to generate a color change-over signal synchronized with
the rotation of the tricolor filter 22. As a result, during a field period
in which the blue light is incident on the light transfer body 8, the
output from the amplifier 26 appears at the blue light output terminal 28B
and then is supplied through the blue light amplifier 32 to the blue light
grid of the Braun tube 37, thereby displaying a blue light image on a
screen of the Braun tube 37. Similarly, during the next field period, a
green light image is displayed on the screen of the Braun tube 37 and
during the next field period, a red light image is displayed on the screen
of the Braun tube 37. As a result, the blue, green and red light images
which are changed over every successive periods are visually composed to
from a color picture image to be visualized.
In FIG. 5 is shown another embodiment of that part of the endoscope
according to the invention which is inserted into the hollow cavity. In
the present embodiment, the same reference numerals as those shown in FIG.
1 designate the same parts as those shown in FIG. 1. The present
embodiment is of a side view type. The light outlet end of the light
transfer body 8 is bent sidewardly and the sheath 14 is provided at its
one side with the glass window 7 which is opposed to the light outlet end
of the light transfer body 8. The light reflected from the object to be
visualized is taken through the glass window 2 provided on the side
surface of the sheath 14 thereinto. A prism 3 causes the light to change
its direction and the light is then incident on the light receiving
surface of the self-scanning type solid state image pick-up device 5 by
means of the lens 4. In the present embodiment, a forceps 1 is projected
through a glass window 13. The forceps 1 is used to pick-up a living body
structure. The front end of a wire 9 extending through the sheath 14 is
secured to a hole 12 formed at one end of a lever 11 pivotally mounted at
its another end on a screw 10. If the wire 9 is pulled out, the lever 11
becomes rotated to change its inclined angle. Thus, the operation of the
wire 9 permits the forceps 1 to locate at any desired position of the
living body structure. In addition, the forceps 1 is secured to the front
end of a cable 16 extending through the sheath 14. Thus, it is possible to
pick-up the living body structure by operating the cable 16. As a result,
the sheath 14 encloses therein the bundle of lead wires 6, light transfer
body 8, cable 16 for driving the forceps 1 and wire 9 for controlling the
position of the forceps 1.
In FIG. 6 is shown a block diagram illustrating a modified embodiment of
the circuit shown in FIG. 2 which is arranged at the outside of the hollow
cavity. In the present embodiment, between the amplifier 26 and the signal
change-over circuit 28 is inserted an analog picture image treating
circuit 29. In the analog picture image treating circuit 29, the picture
signal is differentiated to mkae its contour conspicuous and is subjected
to filtering treatment by a band pass filter or a low pass filter to form
an easily discernible picture image. In this case, if each of the blue,
green and red light picture image signals is subjected to the different
treatment, the timing signal from the color change-over generation circuit
25 may be supplied through a conductor 30 to the analog picture image
treating circuit 29.
In FIG. 7 is shown a block diagram illustrating another modified embodiment
of the circuit shown in FIG. 2 which is arranged at the outside of the
hollow cavity. In the present embodiment, the same reference numerals as
those shown in FIGS. 2 and 6 designate the same parts as those shown in
FIGS. 2 and 6. In the present embodiment, the picture image is digitally
treated by means of a digital computer. In addition, instead of taking out
a part of the illumination light so as to form the color change-over
timing signal, use is made of a tricolor filter 22' shown in FIG. 8 to
form a timing signal. The tricolor filter 22' is provided at a boundary
between the blue light transmitting portion 40 and the green light
transmitting portion 41 with a transparent portion 46 having a given
width, provided at a boundary between the green light transmitting portion
41 and the red color transmitting portion 42 with an opaque portion 47
having a given width, and provided at a boundary between the red light
transmitting portion 42 and the blue light transmitting portion 40 with an
opaque portion 48 having a given width.
The tricolor filter 22' is inserted between the light source 21 and the
light inlet end surface 8a of the light transfer body 8 and rotated at a
given number of rotations by means of the motor 20. In this case, the
picture image signal supplied from the self-scanning type solid state
image pick-up device 5 through the bundle of lead wires 6 to the outside
may be shown, for example, in FIG. 9. In FIG. 9, V.sub.B, V.sub.G and
V.sub.R designate blue, green and red picture image signals, respectively,
and S46, S47 and S48 are color synchronizing signals generated by the
transparent portion 46, and opaque portions 47 and 48, respectively. The
signal S46 is higher than a white level W and the signals S47 and S48 are
lower than a black level B. So, the output signal from the amplifier 26 is
supplied to a level detector 49 which can detect the color synchronizing
signals S46, S47 and S48 on the basis of their levels so as to form blue,
green and red light synchronizing signals which are supplied as trigger
signals to the oscillation circuit 27.
In addition, the output picture image signals from the amplifier 26 is
supplied to an A-D converter 31 to convert an analog signal into a digital
signal which is then supplied to a digital computer 38. In the digital
computer 38, the picture image is digitally treated and recognition of
pattern, .gamma. control, superimposition of the treated picture images,
etc. are digitally effected.
In this case, if an instantaneous treatment is required, the A-D converter
31 must be rapid in conversion speed and small in number of bits. For
example, the conversion speed must be 100 .mu.s to 1 .mu.s and the number
of bits must be on the order of 4 to 5 bits. If the instantaneous
treatment is not required, the conversion speed of the A-D converter 31
may be made slow by making the number of rotations of the motor 20 small
and by making the amount of light of the light source 21 or the gain of
the amplifier 26 small.
The digital picture image signal treated by the digital computer 38 is
supplied to a D-A converter 39 and converted into an analog signal which
is supplied to a signal change-over circuit 43 and a level detection
circuit 44. The signal change-over circuit 43 serves to effect level
detection so as to detect the above mentioned color synchronizing signals
and supplies blue, green and red light signals to blue, green, red light
output terminals 43B, 43G, 43R, respectively. The level detection circuit
44 detects the color synchronizing signals which are supplied as trigger
signals to the horizontal deflection circuit 35 and vertical deflection
circuit 36.
In FIG. 10 is shown one embodiment of a light decomposition optical system
used for the endoscope according to the invention. In the present
embodiment, a light 51 reflected by an object to be visualized and passed
through the lens 4 (FIG. 12) is incident on a pentaprism 52 and a green
light 56, for example, is reflected by a dichroic mirror 54 and blue and
red lights are transmitted therethrough and pass straight ahead. The green
light 56 reflected by the dichroic mirror 54 is reflected again by a
reflecting mirror 55 and incidents on a first solid state image pick-up
device 53. The light 60 transmitted through the dichroic mirror 54 passes
through a light transmission block 57 and arrives at an optical filter
such as a stripe filter 58 which can decompose the light 60 into the blue
and red lights. The blue and red lights are incident on a second solid
state image pick-up device 59.
In FIG. 11 is shown the minimum dimensions of the light decomposition
optical system shown in FIG. 10. In the endoscope, that part thereof which
is inserted into the hollow cavity must be made as small as possible. The
light decomposition optical system enclosed in the front end part of the
endoscope occupies the largest space if compared with the space occupied
by any other constitutional elements enclosed in the front end part of the
endoscope, and as a result, the dimension of the light decomposition
optical system must be made minimum. Particularly, it is important to make
a length 63 of the pentaprism 52 small. Calculations have yielded the
following lengths and angles.
Let lengths 61, 62, 72 be a, the length 63 is given by a(tan(.pi./8 + 1)
and a length 71 is given by a (1 + .sqroot.2 ). Angles 64, 75 and 76 are
.pi./2 radians, angles 65, 66, 67, 74 are 5/8.pi. radians, respectively,
and an angle 73 is 3/8.pi. radians.
In FIG. 12 is shown one embodiment of that part of the endoscope according
to the invention which is inserted into the hollow cavity and which
comprises the light decomposition optical system shown in FIG. 10. The
part shown in FIG. 12 is of a direct view type.
In the present embodiment, a light from the light source is passed through
the light transfer body 8 and the glass window 7 and illuminates an object
to be visualized.
A light reflected by the object to be visualized is taken through the glass
window 2 into the sheath 14. The image of the object to be visualized is
formed by the lens 4, pentaprism 52, light transmission block 7, solid
state image pick-up devices 53, 59 and decomposed and changed into
electric signals. The bundle of lead wires 6 encloses therein a lead wire
through which is passed a signal for driving the solid state image pick-up
devices 5, 9 and a lead wire for deriving image signals from the solid
state image pick-up devices 53, 59.
In FIG. 13 is shown another embodiment of the side view type of that part
of the endoscope according to the invention, which comprises the light
decomposition optical system shown in FIG. 10. In the present embodiment,
a light from the light source is led through the light transfer body 8
into the sheath 14 and illuminate an object to be visualized through the
glass window 7. A light reflected by the object to be visualized is taken
through the glass window 2 into the sheath 14 and an image of the object
to be visualized is formed by the prism 3, lens 4, pentaprism 52, light
transmission block 57 and solid state image pick-up devices 53, 59, and
decomposed and changed into electric signals. The other construction and
the operation thereof are substantially the same as those described with
reference to FIG. 5.
FIG. 14 is shown another embodiment of a circuit arranged outside the part
shown in FIG. 12 or FIG. 13. In the present embodiment, use is made of a
lamp as the light source 21 and a light from the light source 21 is led
through the light transfer body 8 into the hollow cavity. The oscillation
circuit 27 supplies a signal for driving the solid state image pick-up
devices 53, 59, signals for driving memories 135, 136 which can memorize
the image signal, and synchronizing signals used for the horizontal
deflecting circuit 35 and vertical deflecting circuit 36 for sweeping
electron beams of the color Braun tube 37. In the present embodiment, the
dichroic mirror 54 serves to reflect the green light and transmit the red
and blue lights therethrough and the optical filter 58 is composed of a
stripe filter for decomposing the red light and the blue light alternately
every one horizontal scanning period. The output signal from the first
image pick-up device 53, that is, the green light image signal is
amplified by an amplifier 133 and then amplified by the green amplifier 33
to a voltage which is sufficient to operate a green grid of the color
Braun tube 37. The image signal from the second solid state image pick-up
device 59 is amplified by an amplifier 132 and supplied to the signal
change-over circuit 28 which can change-over the image signal into red and
blue light signals by the synchronizing signal received from the
oscillation circuit 27. The blue and red light signals are memorized in
memories 135 and 136 and then supplied to the blue and red light
amplifiers 32, 34, respectively. During one horizontal scanning period,
one of the color signals is memorized in the memory and during the next
one horizontal scanning period, the other color signal is memorized in the
memory.
At the same time, the color signals previously memorized are supplied to
the blue and red light amplifiers 32, 34, respectively. In the present
embodiment, the signal change-over circuit 28 makes use of a high speed
operation switch such as a semiconductor analog switch, etc.
The endoscope according to the present embodiment is capable of decomposing
the impage of the object to be visualized into three color lights to
generate respective color signals in that part of the endoscope which is
inserted into the hollow cavity, of leading the color signals to the
outside and of displaying the color picture image on the color Braun tube.
This permits a highly compact construction which is easy in operation if
compared with the prior art endoscope which makes use of the vidicon tube.
In the present embodiment, the optical filter 58 is arranged in front of
the second solid state image pick-up device 59. Alternatively, the optical
filter 58 may be arranged in front of the first solid state image pick-up
devices 53. In this case, it is a matter of course that the dichroic
mirror 54 must reflect two color lights.
In FIG. 15 is shown a modified embodiment of the circuit shown in FIG. 14.
In the present embodiment, the output from the amplifier 132 is supplied
directly to and through a delay circuit 144 to the signal change-over
circuit 28 whose output is directly supplied to he blue and red light
amplifiers 32, 34. In the present embodiment, it is possible to omit the
memories 135, the shown in FIG. 14.
In FIG. 16 is shown a modified embodiment of the light decomposition
optical system shown in FIG. 10. In the present embodiment, a light 51
reflected by an object to be visualized and passed through the lens 4
(FIG. 19) is incident on the pentaprism 54 which can reflect, for example,
a green light 56 and causes blue and red lights to pass straight ahead.
The green light 56 reflected by the dichroic mirror 54 is reflected again
by the reflecting mirror 55 and incident on the first solid state imge
pick-up device 53. The light transmitted through the dichroic mirror 54
passes through the light transmission block 57. A red light 90, for
example, is reflected by a dichroic mirror 88 and a blue light 93
transmits therethrough and passes straight ahead. The red light 90
reflected by the dichroic mirror 88 is incident on the second solid state
image pick-up device 59 and the blue light 93 transmitted through the
dichroic mirror 88 is transmitted through a light transmission block 91
and incident on a third solid state image pich-up device 92.
In FIG. 17 is shown another embodiment of a light decomposition optical
system used for the endoscope according to the invention. In the present
embodiment, the light 51 reflected by an object to be visualized and
passed through the prism 3 and the lens 4 (FIG. 20) is incident on a light
transmission block 94 and a green light 96, for example, is reflected by
the dichroic mirror 54 and the blue and red lights 100 are transmitted
through the dichroic mirror 54 and pass straight ahead.
The green light 96 reflected by the dichroic mirror 54 is incident on the
first solid state image pick-up device 53 and the light 100 transmitted
through the dichroic mirror 54 pass through a light transmission block 97
and arrive at the optical filter 58 such as the stripe filter which can
decompose the lights into blue and red lights which incident on the second
solid state image pick-up device 59.
In FIG. 18 is shown the minimum dimensions of the light decomposition
optical system shown in FIG. 16. Calculations have yielded the following
lengths and angles. Let lengths 61, 62, 72, 85 be a, the length 63 is also
given by a (tan(.pi./8) + 1) similar to the embodiment shown in FIG. 10
and a length 84 is given by a.sqroot.2. Angles 64 and 75 are .pi./2
radians, angles 65, 66, 67, 68 and 74 are 5/8.pi. radians, an angle 80 is
3/4.pi. radians, an angle 73 is 3/8.pi. radians and angles 81, 82 and 83
are .pi.4 radians, respectively.
In FIG. 19 is shown one embodiment of that part of the endoscope according
to the invention which is inserted into the hollow cavity and which
comprises the light decomposition optical system shown in FIG. 16. The
part shown in FIG. 19 is of a direct view type. In the present embodiment,
a light from the light source is led through the light transfer body 8
into the sheath 14 and illuminated through the glass window 7 on an object
to be visualized. A light reflected by the object to be visualized is
taken through the glass window 2 into the sheath 14 and the image of the
object to be visualized is formed, decomposed and changed into electric
signals by the lens 4, pentaprism 52, light transmission blocks 57, 91 and
image pick-up devices 53, 59, 92. Similar to the embodiment shown in FIG.
12, the bundle of lead wires 6 encloses therein lead wires for deriving
the image signals from the image pick-up devices 53, 59 and 92.
In FIG. 20 is shown a further embodiment of the side view type of that part
of the endoscope according to the invention, which comprises the light
decomposition optical system shown in FIG. 17.
In the present embodiment, the light from the light source (FIG. 21) is
lead through the light transfer body 8 into the sheath 14 and illuminates
through the glass window 7 the object to be visualized. The light
reflected by the object to be visualized is taken through the glass window
2 into the sheath 14 and the image of an object to be visualized is
formed, decomposed and changed into electric signals by the prism 3, lens
4, light transmission blocks 94, 97, stripe filter 58 and image pick-up
devices 53, 59. The other construction and the operation thereof are
substantially the same as those described with reference to FIG. 5.
In FIG. 21 is shown a further embodiment of the circuit arranged outside
the sheath 14 shown in FIG. 19. In the present embodiment, a lamp is used
as the light source 21 for illuminating an object to be visualized. The
light from the light source 21 is led through the light transfer body 8
into the hollow cavity. The oscillation circuit 27 supplies signals for
driving the image pick-up devices 53, 55, 92 and synchronizing signals to
an analog register 159 for reversing the image signal during one
horizontal period and to the horizontal deflection circuit 35 and vertical
deflection circuit 36 for sweeping the electron beams in the color Braun
tube 37. In the present embodiment, the dichroic mirror 54 reflects the
green light and transmits the red and blue lights and the dichroic mirror
88 reflects the red light and transmits the blue light. The green light 56
is reflected again by the reflecting mirror 55 and incident on the solid
state image pick-up device 53, so that the green light is reflected twice
times in total. The red light 90 is reflected by the dichroic mirror 88
one time only. The blue light 93 is transmitted through both the dichroic
mirrors 54, 88 and hence is not reflected at all.
As a result, the red light is reversed with respect to the green and blue
lights and hence it is necessary to reverse the output electric signal for
the red light with respect to the output electric signals for the other
color lights within one scaning period. For this purpose, the green image
signal from the image pick-up device 53 is amplified by an amplifier 253
and supplied to a delay circuit 157 for delaying the signal by one
horizontal scanning period and then amplified by the green amplifier 33 to
a voltage which is sufficient to operate the green grid of the color Braun
tube 37. The blue image signal from the image pick-up device 92 is
amplified by an amplifier 154 and supplied to a delay circuit 158 for
delaying the signal by one horizontal scanning period and then amplified
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