Electronic endoscope apparatus having isolated patient and secondary circuitry

This electronic endoscope apparatus comprises an endoscope provided with an imaging apparatus converting a light information of an object to be imaged to an electric signal and a signal processing apparatus processing the output signal of the imaging apparatus to be a video signal. The signal processing apparatus has an isolating device isolating and transmitting the information from the imaging apparatus from the patient circuit side to the secondary circuit side and a converting device converting the signal from the imaging apparatus to a signal adapted to be transmitted by the isolating device and delivering it to the isolating device.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
This invention relates to an electronic endoscope apparatus wherein the 
patient circuit side and secondary circuit side are insulated from each 
other. 
2. Related Art Statement: 
Recently, there is extensively utilized an endoscope whereby organs within 
a body cavity can be observed by inserting an elongate insertable part 
into the body cavity or various curing treatments can be made as required 
by using a treating tool inserted through a treating tool channel. 
There are also suggested various electronic endoscopes of a system wherein 
such solid state imaging device as a charge coupled device (CCD) is 
provided as an imaging means in the tip part of an insertable part so that 
a picture image information may be taken out as a photoelectrically 
converted electric signal. 
Now, in the case of a medical electronic endoscope, a circuit part (patient 
circuit) inserted into the body of a patient and a circuit part (secondary 
circuit) connected to such peripheral device as a monitor must be isolated 
from each other. 
FIG. 14 shows an example of the formation of such electronic endoscope 
apparatus. 
In this drawing, the image of an object to be imaged is formed on a solid 
state imaging device 3 by an image forming optical system 2 and the signal 
photoelectronically converted by this solid state imaging device 3 is fed 
to a video signal processing circuit 5 through a cable 4. As this video 
signal processing circuit 5 is connected to such peripheral device as a 
monitor, the video signal must be isolated on the patient circuit side and 
secondary circuit side by an isolation circuit 6 within the video signal 
processing circuit 5. 
There is such isolation system as a system wherein the output of the solid 
state imaging device 3 is passed directly through an isolation transformer 
or a system wherein, for example, in the case of a CCD, a signal taking 
the difference between a signal delaying the original signal by half the 
pixel sampling period and the original signal is passed through an 
isolation transformer to sample the effective signal part. 
As such a Prior Art example mentioned above, one is disclosed in a Japanese 
utility model application Laid Open No. 198161/1982. 
However, in the case of isolating the patient circuit and secondary circuit 
from each other, the output of the solid state imaging device has a low 
frequency component in the signal and therefore can not be directly passed 
through the isolation transformer. Also, in the case of the CCD output, 
the signal taking the delay difference can be passed through the isolation 
transformer. However, there is a problem that, when the signal is passed 
through the transformer, the high frequency component of the signal will 
attenuate and therefore no positive sampling will be able to be made. 
Here, measures of reducing the noises of the solid state imaging device may 
be positively taken on the patient circuit side. In this case, there is a 
defect that, as the signal band is only a base band, the signal can not be 
transmitted with the isolation transformer. 
OBJECT AND SUMMARY OF THE INVENTION 
An object of the present invention is to provide an electronic endoscope 
apparatus wherein the patient circuit side and secondary circuit side can 
be well isolated from each other without deteriorating the picture 
quality. 
Another object of the present invention is to provide an electronic 
endoscope apparatus wherein the patient circuit side and secondary circuit 
side can be well isolated from each other and the solid state imaging 
device output ca be processed to positively reduce noises. 
A further object of the present invention is to provide an electronic 
endoscope apparatus wherein the patient circuit side and secondary circuit 
side can be well isolated from each other and few noises are mixed in. 
The electronic endoscope apparatus of the present invention is provided 
with an endoscope provided with an imaging means converting a light 
information of an object to be imaged to an electric signal and a signal 
processing means processing the output signal of the above mentioned 
imaging means to be a video signal. The above mentioned signal processing 
means has an isolating means isolating and transmitting the information 
from the above mentioned imaging means to the secondary circuit side from 
the patient circuit side and a converting means converting the signal from 
the above mentioned imaging means to a signal adapted to be transmitted by 
the above mentioned isolating means and delivering it to the above 
mentioned isolating means. The above mentioned converting means is a 
modulating means or A/D converting means. Further, the electronic 
endoscope apparatus of the present invention is provided with noise 
reducing means in the front step of the above mentioned converting means. 
The other features and advantages of the present invention will become 
apparent enough with the following explanation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
As shown in FIG. 2, an electronic endoscope 11 is provided with an 
elongate, for example, flexible insertable part 12 to the rear end of 
which thick operating part 13 is connected. A flexible universal cord 14 
is extended sidewise from the rear end part of the above mentioned 
operating part 13 and is provided with a connector 15 at the tip. This 
connector 15 is to be connected to a connector receptacle 18 of a video 
processor 16 containing a light source apparatus and video signal 
processing circuit. The above mentioned video processor 16 is to be 
connected to a color monitor 17. 
On the tip side of the above mentioned insertable part 12, a rigid tip part 
19 and a curvable part 20 adjacent to this tip part 19 and curable 
rearward are sequentially provided. The above mentioned operating part 13 
is provided with a curving operation knob 21 so that, by rotating this 
curving operation knob 21, the above mentioned curvable part 20 can be 
curved vertically 1 to the right and left directions. The above mentioned 
operating part 13 is provided with an inserting part 22 communicating with 
a treating tool channel provided within the above mentioned insertable 
part 12. 
As shown in FIG. 1, in the above mentioned tip part 19, an image forming 
optical system 2 is provided and has a solid state imaging device 3 as an 
imaging means arranged in the image forming position. Here, the solid 
state imaging device 3 includes a CCD (charge coupled device) and MOS type 
solid state imaging device. A signal transmitting and receiving cable 4 is 
connected to the above mentioned solid state imaging device 3, is inserted 
through the above mentioned insertable part 12 and universal cord 14, is 
connected to the above mentioned connector 15 and is connected through 
this connector 15 and connector receptacle 18 to a video signal processing 
circuit 35 contained in the above mentioned video processor 16. By the 
way, in case a synchronous system is used for the color imaging system, a 
color fiber array in which color filters respectively transmitting the 
color lights of red (R), green (G) and blue (B) are arranged in the mosaic 
form is provided on the front surface of the above mentioned solid state 
imaging device 3. In the above mentioned tip part 19, a light distributing 
lens 25 is provided and a light guide 26 is connected to the rear end side 
of this light distributing lens 25. This light guide 26 is inserted 
through the above mentioned insertable part 12 and universal cord 14 and 
is connected to the above mentioned connector 15. The illuminating light 
emitted from a light source apparatus not illustrated contained in the 
above mentioned video processor 16 enters the entrance end of the above 
mentioned light guide 26, is led to the tip part 19 by this light guide 
26, is emitted from the exit end and is radiated onto an object 1 to be 
imaged through the light distributing lens 25. By the way, in case a frame 
sequential system is used for the color imaging system, a light source 
apparatus emitting such frame sequential illuminating lights as of R, G 
and B is used for the above mentioned light source apparatus. 
The light returning from the above mentioned object 1 is made to form an 
image on the solid state imaging device 3. This object image is 
photoelectrically converted by the solid state imaging device 3 and is 
delivered as a video signal to the above mentioned processing circuit 35 
through the cable 4. In this video signal processing circuit 35, the above 
mentioned video signal has such noise reducing measures as a correlated 
double sampling applied in the noise reducing circuit 37. 
The output signal of the above mentioned noise reducing circuit 37 is 
passed through a low-pass filter 38 to have the component of only the base 
band of the video signal taken out. The output signal of this low-pass 
filter 38 is modulated by a modulating circuit 39. The modulating system 
is such sine wave modulation as an amplitude modulation (AM), frequency 
modulation (FM) or phase modulation (PM), such pulse modulation as a pulse 
amplitude modulation (PAM), pulse frequency modulation (PFM), pulse 
position modulation (PPM) or pulse width modulation (PWM) or such digital 
modulation as a pulse cord modulation (PCM), difference PCM (DPCM), pulse 
number modulation (PNM). Any modulation system will do. In the case of 
transmitting a plurality of kinds of signals, a composite modulating 
system combining different modulating systems may be used. 
The signal modulated by the above mentioned modulating circuit 39 is 
transmitted from the patient circuit to the secondary circuit through an 
isolating device 40. In case the modulating system is, for example, an AM 
modulation, such high frequency transformer 61 as is shown in FIG. 3 is 
used. On the primary side of this high frequency transformer 61, a 
modulation signal is input through a driver 62 and, from the secondary 
side, the modulation signal is output. For example, in case the modulating 
system is an FM modulation, the above mentioned high frequency transformer 
or such high frequency photocoupler 63 as is shown in FIG. 4 is used. The 
above mentioned photocoupler 63 has an LD 64 and photodiode (which may be 
a phototransistor) 65. The above mentioned modulation signal is input into 
the above mentioned LED 64 through a driver 66 and is converted to a 
photosignal by this LED 64. The light of the above mentioned LED 64 is 
received is converted to an electric signal and is output. 
The above mentioned isolating device 40 may be such using optical fibers 71 
as in shown in FIG. 5. In this case, the above mentioned modulation signal 
is input into photomodulator 72, the light modulated by the above 
mentioned photomodulator 72 is emitted, for example, from an LED 73, 
enters the entrance end of the optical fibers 71, is emitted from the exit 
end of the optical fibers 71, is input into a photodemodulator, is 
converted to an electric signal in this photodemodulator 74 and is output. 
The above mentioned isolating device 40 can endure a high voltage of at 
least 4 Kv, for example, on the basis of the safety standards for medical 
devices is preferably used. 
The isolated signal output from the above mentioned isolating device 40 is 
demodulated to the original signal by the demodulator, is transmitted to 
the main processing circuit 42 and is applied to a predetermined signal 
process and a video signal from this main processing circuit 42 is input 
into a monitor 17. The object image is displayed by this monitor 17. 
Thus, according to this embodiment, after the video signal is modulated, an 
isolation is made, therefore without deteriorating the picture quality, 
the patient circuit side and secondary circuit can be positively isolated 
from each other. Further, as the isolating process can be made after the 
noises are reduced, the noise reducing process of the solid state imaging 
device output can be positively made. 
FIGS. 6 and 7 show the second embodiment of the present invention. 
This embodiment shows an example of an electronic endoscope apparatus 
wherein a color difference line sequential system color CCD is used. 
By the way, the same reference numerally are attached to the same circuits 
as in FIG. 1. Here, the component of only the base band of the output 
signal from which unnecessary components have been removed through the 
low-pass filter 38 is such luminance signal on which a color carrier is 
overlapped as is shown in FIG. 7A. This signal is separated into a 
luminance signal (FIG. 7B) and color carrier (FIG. 7C) by the low-pass 
filter 43 and band-pass filter 44. This luminance signal is modulated by 
the modulating circuit 39 the same as in the first embodiment and is 
transmitted to the secondary circuit from the patient circuit through the 
isolating device 40. The isolated luminance signal is likewise demodulated 
by the demodulating circuit 41 and is transmitted to the main processing 
circuit 42. On the other hand, the color carrier signal is a color 
difference signal as balance modulated, is therefore input as it is into 
the isolating device 45 and is transmitted to the secondary circuit from 
the patient circuit. In this case, a high frequency transformer is used 
for the isolating device. The isolated color carrier signal is demodulated 
by the demodulating circuit 46 and is transmitted to the main processing 
circuit 42 and is processed together with the above mentioned luminance 
signal. 
The other formations, operations and effects are the same as in the first 
embodiment. 
FIG. 8 shows the third embodiment of the present invention. 
This embodiment is an example of an electronic endoscope wherein is used a 
color CCD of a system of obtaining color information by sampling. The 
output of the CCD 3 passes through the noise reducing circuit 37 and is 
separated into respective color signals by the sampling circuit 47. Here, 
in case the arrangement of the color filters of the CCD 3 is like the 
Bayer arrangement in which the informations of R and B are obtained in 
each line, the signals will be a G signal and sequentialized R/B signal. 
Here, the G signal is modulated by the modulating circuit 39 the same as 
in the first embodiment and is transmitted to the secondary circuit from 
the patient circuit through the isolating device 40. On the other hand, 
the sequentialized R/B signal is also modulated by the modulating circuit 
48 in the same manner and is transmitted to the secondary circuit from the 
patient circuit through the isolating device 45. In the secondary circuit, 
the G signal and R/B signal are demodulated respectively by the 
demodulating circuits 41 and 46 and are transmitted to the main processing 
circuit 42 to be processed the same. 
The other formations, operations and effects are the same as in the first 
embodiment. 
FIGS. 9 and 10 show the fourth embodiment of the present invention. 
Generally, the band of the color difference signal obtained from the solid 
state imaging device colorized by the color filter array is about f=0.5 
MHz. Therefore, as shown in FIG. 10A, in the vertical direction, the same 
color difference signal for 2H periods is sufficient. Therefore, the 
electronic endoscope apparatus of a system of sequentializing and 
isolating the color difference signal is shown as the fourth embodiment in 
FIG. 9. The output of the solid state imaging device 3 is transmitted to 
the video signal processing circuit 35 through the cable 4. The luminance 
signal Y and color difference signals R-Y and B-Y are finally obtained by 
the pre-processing circuit 49 from the video signal. Here, the color 
difference signals R-Y and B-Y become such sequentialized signals as are 
shown in FIG. 10C in the sequentialized circuit 50. Therefore, the same as 
in the above described embodiment 3, the luminance signal and color 
difference signals are modulated respectively by the modulating circuits 
39 and 48 and are transmitted to the secondary circuit from the patient 
circuit respectively through the isolating devices 40 and 45. The 
luminance signal is demodulated by the demodulating circuit 41 and is 
transmitted to the main processing circuit 42. On the other hand, the 
color difference signals are demodulated by the demodulating circuit 46, 
are then synchronized by the synchronizing circuit 51, are transmitted to 
the main processing circuit 42 and are processed together with the above 
mentioned luminance signal. 
Here, even if the color difference signals are not made sequential, the 
isolation will be possible. In such case, the modulating circuit, 
demodulating circuit and isolating device will increase by one. 
The other formation, operations and effects are the same as in the first 
embodiment. 
FIG. 11 shows the fifth embodiment of the present invention. 
This embodiment is an example of using a system in which the color 
difference signals are modulated at right angles and are then isolated. 
In this embodiment, the output of the solid state imaging device 3 is 
transmitted to the video signal processing circuit 35 through the cable 4. 
The video signal is converted to a final luminance signal and a chromatic 
signal modulated at right angles. The luminance signal is modulated by the 
modulating circuit 39 the same as in the first embodiment and is 
transmitted to the secondary circuit side through the isolating device 40. 
The chromatic signal is transmitted as it is to the secondary circuit side 
through the isolating device 45. The luminance signal is demodulated by 
the demodulating circuit 41 and is synthesized with a synchronous signal 
and the above mentioned chromatic signal in the NTSC output circuit 53 and 
is made an NTSC signal to be output. 
The other formations, operations and effects are the same as in the first 
embodiment. 
Thus, according to the first to fifth embodiments, there are effects that, 
on the patient circuit side, noises can be positively reduced and further, 
the patient circuit side and secondary circuit side can be well isolated 
from each other. 
Also, in the pre-signal processing circuit receiving the solid state 
imaging device output, various signals and timing pulses can be processed 
positively and, particularly, in case a mosaic color filter system color 
solid state imaging device is used, the luminance and color signals can be 
generated comparatively easily. 
FIG. 12 shows the sixth embodiment of the present invention. 
In this embodiment, the light returning from the object 1 is made to form a 
image on the solid state imaging device 3. This object image is 
photoelectrically converted by the solid state imaging device 3 and is 
delivered as a video signal to the video signal processing circuit 61 
through the cable 4. In this video signal processing circuit 61, the above 
mentioned video signal is first subjected to such noise reducing measures 
as the correlated double sampling in the noise reducing circuit 62. The 
output of this noise reducing circuit 62 is sample-held for each pixel. 
The output of the above mentioned noise reducing circuit 62 is A/D 
converted at the pixel read-out period by the A/D converter 63. That is to 
say, by this A/D converter 63, the information of the respective pixels of 
the solid state imaging device 3 is converted to a digital information. 
The video signal converted to this digital signal is transmitted to the 
secondary circuit from the patient circuit through the isolating device 
64. 
This isolating device 64 is a photocoupler or pulse transformer. The 
digital signal transmitted to the secondary circuit by the above mentioned 
isolating device 64 is processed as predetermined by the digital signal 
processing circuit 65 and is then converted to an analogue signal by the 
D/A converter 66. The video signal from this analogue signal processing 
circuit 67 is output to the color monitor 17 or the like. The above 
mentioned digital signal processing circuit 65 includes, for example, a 
memory function used to make the picture image stationary. 
The patient circuit pulse generator connected to the noise reducing circuit 
62 and A/D converter 64 and the secondary circuit pulse generator 69 
connected to the digital signal processing circuit 65, D/A converter 66 
and analogue signal processing circuit 67 are connected with each other 
through the timing pulse isolating device 70. Various pulses generated 
from the above mentioned patient circuit pulse generator 68 and secondary 
circuit pulse generator 69 are timed by the signal transmitted through 
this timing pulse isolating device 70. 
By the way, this embodiment can be applied to both of the frame sequential 
system and synchronous system by making the digital signal processing 
circuit 65 and analogue signal processing circuit 67 correspond to the 
frame sequential system or synchronous system. Also, in the case of the 
frame sequential system, the above mentioned digital signal processing 
circuit 65 may be provided with frame memories corresponding to the 
respective colors of R, G and B. 
Thus, according to this embodiment, the video signal from the solid state 
imaging device 3 is converted to a digital signal and is isolated. 
Therefore, no noise mixes in, the picture quality does not deteriorate and 
the patient circuit sidle and secondary circuit side can be isolated from 
each other. 
Also, as the signal having passed through the noise reducing circuit 62 is 
A/D converted, the noises are less. 
The other formations, operations and effects are the same as in the first 
embodiment. 
FIG. 13 shows the seventh embodiment of the present invention. 
This embodiment is an example of the case of using the synchronous type for 
the color imaging system. A filter array is provided on the front surface 
of the solid state imaging device 3. 
In this embodiment, the output of the solid state imaging device 3 is 
delivered to the video signal processing circuit 71 through the cable 4. 
In this video signal processing circuit 71, the output signal of the above 
mentioned solid state imaging device 3 is subjected to noise reducing 
measures in a noise reducing circuit 72 and is .gamma.-corrected by a 
.gamma.-correcting circuit 73. The output of this .gamma.-correcting 
circuit 73 is input into a luminance signal generating circuit 74 and 
color difference signal generating circuit 75. A luminance signal Y is 
produced in the luminance signal generating circuit 74 and sequentialized 
color difference signals R-Y and B-Y are produced in the color difference 
signal generating circuit 75. These luminance signal Y and color 
difference signals R-Y and B-Y are respectively converted to digital 
signals by an A/D converter 76. This digital signal is transmitted to the 
secondary circuit from the patient circuit through an isolating device 77. 
The digital signal transmitted to the secondary circuit is converted to an 
analogue luminance signal Y and color difference signals R-Y and B-Y. This 
analogue luminance signal Y and color difference signals R-Y and B-Y are 
input into an analogue signal processing circuit 80, are processed as 
determined and are then output. The patient circuit pulse generator 51 
connected to the noise reducing circuit 72, .gamma.-correcting circuit 73, 
luminance signal generating circuit 74, color difference signal generating 
circuit 75 and A/D converter 76 and the secondary circuit pulse generator 
82 connected to the digital signal processing circuit 78, D/A converter 79 
and analogue signal processing circuit are connected with each other 
through a timing pulse isolating device 83. By the signal transmitted 
through this timing pulse isolating device 83, various pulses generated 
from the above mentioned patient pulse generator 81 and secondary circuit 
pulse generator 82 are timed. 
The other formations are the same as of the sixth embodiment. 
According to this embodiment, as the band of the color difference signal is 
about 0.5 MHz, the sampling frequency of the color signal can be made low 
for the luminance signal and the capacity of the memory or the like within 
the digital signal processing circuit 78 can be also made small. 
The other operations and effects are the same as in the sixth embodiment. 
By the way, in the sixth and seventh embodiments, the isolating devices 64 
and 77 are provided just after the A/D converter 63 and 76 but may be 
provided in any position of the digital signal part between the A/D 
converters 63 and 76 and D/A converters 66 and 79. 
Thus, according to the sixth and seventh embodiments, the signal from the 
imaging means is converted to a digital signal and is then transmitted to 
the secondary circuit system by the isolating means and therefore there 
are effects that less noises are mixed in and the patient circuit side and 
secondary circuit side can be isolated from each other. 
By the way, the present invention can be applied not only to an electronic 
endoscope wherein a solid state imaging device is arranged in the tip part 
of the insertable part but also to an endoscope apparatus used with an 
externally fitted television camera connected to the eyepiece part of such 
endoscope with which a naked eye observation is possible as a fiber scope. 
In this invention, it is apparent that working modes different in a wide 
range can be formed on the basis of this invention without deviating from 
the spirit and range of the invention. This invention is not limited to 
its specific working modes except being limited by the appended claims.