JPS6136717A - Endoscope using solid-state image pickup element - Google Patents

Abstract

PURPOSE:To pick up images efficiently and to attain an excellent capacity of a solid-state image pickup element of no sensitivity degradation by transferring a required picture signal when an achromatic color forming part traverses the incidence end of light during rotation of a rotary three-color filter where colored light and achromatic light forming parts are formed divisionally. CONSTITUTION:While each opaque segment part of a three-color filter 35 passes a light incidence end 41 of a photoconductor 40, the preceding color field picture signal stored in an image pickup part 71 of a solid-state image pickup element 70 is transferred to a storage part 72. This signal is transferred from the storage part 72 to a storage part 73 while one color filter opaque segment passes the incidence end 41 and is stored in one of DRAM memories (red, green and blue) 77-79 and is transferred to an output processor encoder 90 simultaneously. The encoder 90 synthesizes two preceding stored signals in memories 77-79 and a direct transfer signal of a switching circuit 91 to generate a composite video signal. This signal is outputted from the encoder 90 once in the one-field period of 1/(60)sec, and this one-field period and the next one-field period are combined to reproduce one-frame components of picture by a pair of memories.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to an endoscope for observing the inside of a living body cavity or a cavity of another subject. The present invention relates to an endoscope capable of extracting sequential color image signals.

"Technical Background of the Invention" Color television cameras using solid-state image sensors as image sensors are conventionally well known, and endoscopes using this technology are also well known. In order to extract a television signal as a color image, k is 1. Usually, an open image element has a minute color filter called a mosaic filter for each pixel. However, in endoscopes, a solid-state image sensor is placed in the focal plane of the imaging optical system of the observation head at the tip instead of the imager, so the area of the solid-state image sensor is extremely small. things are required.

Therefore, if a mosaic filter is attached to such a small-area element (therefore, there is a limit to the total number of pixels that can be used), there is a drawback that the sensitivity will be reduced by a few fractions of a second.

The same can be said of a type of endoscope that uses a conventional image guide made of an optical fiber bundle and attaches a solid-state image pickup device to an eyepiece provided in a hand-operated unit via a relay optical system.

In order to solve the lack of point I, instead of using a color mosaic filter, a color disk having red, green, and blue color filter components was installed between the white light source and the illumination light guide for illuminating the object. The subject is placed and rotated, and the subject is sequentially illuminated with three colored lights. Field image signals for each color of light are extracted from the solid-state image sensor, and these are processed in a so-called field sequential manner.
A method has been proposed in which a color image is obtained by synthesizing images separated into three colors on a color CRT screen using the following formula. Such a field-sequential endoscope is disclosed in U.S. Patent Nos. 2 and 7.
64,149, Japanese Patent Application Laid-open No. 53-90685, and US Pat. No. 4,074,306.

In such an endoscope, image signals corresponding to each color light component that enters the imaging section of the solid-state image sensor and undergoes photoelectric conversion are
The image signals must be transmitted sequentially and efficiently so as not to overlap with image signals corresponding to the next color light component.

Therefore, the present invention seeks to provide an endoscope that can satisfy the above-mentioned requirements.

According to this invention, a solid-state image sensor is used as a camera section,
A rotating three-color filter is arranged between the light source and the light input end of the illumination light guide that guides light to illuminate the subject from the outside,
The object to be examined is illuminated with three colored lights in time series, and a color image signal corresponding to each color field is extracted from the solid-state image pickup device. and an endoscope so as to transfer the image signal captured by the solid-state image sensor to the image signal storage section when the non-color light forming portion crosses the light incident end during rotation of the rotating three-color filter. The above object can be achieved by configuring the mirror.

According to the present invention, in addition to the above configuration, when one colored light forming portion and the non-colored light forming portion connected thereto cross the light incident end during rotation of the three-color filter, the image signal accumulating portion It can also be configured to transfer one field's worth of accumulated color image signals to the 20th pixel signal storage section.

“Embodiment J of the Invention The following is a description based on specific detailed embodiments of the present invention.

In FIG. 1, the color video endoscope system having the configuration according to the present invention is roughly divided into an endoscope main body 10, a control unit 20, and a controller 7). The control unit 20 provides a hiteo output signal via an output processor/encoder 90 to a monitor (not shown) for displaying a video image. The endoscope main body 10 includes a distal end portion including an observation head, a curved portion, and an operation portion (the configuration of the video endoscope described above is well known and is therefore omitted from illustration). The control unit 12 and the endoscope main body 10 are connected through an unillustrated connection. Further, the control unit 12 and the endoscope main body 10 are similarly connected to a machine/
connected by electrical connections. These connections are also well known in the art. The broken line in Figure 1 is
This is for distinguishing between the endoscope main body 10 and the control unit 20. The illumination light for the object (not shown) is supplied from the power source 3.
0 power is supplied from the xenon light source 31 to an infrared cut filter 32, a condensing filter 33, a rotating ND filter 34 for adjusting the amount of light, and a rotating three-color filter 3 having three-color light component regions of red, green, and blue.
5 (described later), the light incident end 41 of the illumination light guide 40 is removably inserted into the control unit 20 via the
be guided by. The illumination light guide illuminates the subject from the distal end of the endoscopic bell body 10 (not shown), just like a conventionally known endoscope having an image guide. In addition, in the figure, 34
A and 35A are motors driven by the auxiliary power source 51 to rotate the ND filter and the three-color filter at a constant speed, respectively.

At the distal end (not shown) of the endoscope main body 100, there is a COD at the focal plane of an imaging optical system (also not shown).

Imaging section 7 of solid-state imaging device 70 such as BBD or CPD
1 is placed. The embodiment shown in FIG. 1 shows a frame transfer type CCD. The image signal accumulated in the imaging section T1 is transferred to the accumulation section 72 of 1s1,
It is accumulated and transferred to the second accumulation section 73, and the amplification circuit 7
4 to video processor T5. Furthermore, as mentioned above, this pulse signal is a drive signal for horizontal scanning and vertical scanning from the image sensor timing circuit 81 which is controlled by the digital timer and synchro generator 80, and is a driving signal for horizontal scanning and vertical scanning. The output signal is transferred to the first storage section 72 and the second storage section T3, and the output signal is amplified and returned to the control unit 20.

The control unit 20 mainly includes a light source 31, a three-color filter 35, a digital timer and synchro generator 80, an auxiliary power supply 51, an image sensor timing circuit 81, a video processor γ5 that receives an output signal from the solid-state image sensor γ0, and an A/D converter 76. , a red memory 77, a green memory 78, and a positive memory 79 for accepting and temporarily storing signals corresponding to the output of the solid-state image sensor 70 for each color field light; (Gl, blue (Bl signal and (
Alternatively, the output processor/encoder 90 forms an encoded video signal such as an NTSC signal, and has a switching circuit 91 that controls a signal corresponding to a color field to the encoder 90. Note that the operating section of the internal stirrup (not shown) has a squaw fwIt separate circuit 92, an image sensor output setup circuit 93, and an image sensor pulse control circuit 94, which are used for each purpose of the scope and for controlling the control unit 20. It is for adjustment.

As is clear from FIG.
, green 102, blue 103, and opaque segment portions (non-color light forming portions) 104105 and 106 are provided between each color filter portion. The three-color filter 35 rotates at a constant speed under the control of a synchronizer 80, so that each color filter section 101, 102, 103 traverses the light entrance end 41 of the light guide 40 within about 1/60 seconds. Figures 1 and 2
As shown in the figure, a pair of light receiving elements 111 and 112 are arranged around the periphery of a color filter 350. Correspondingly, a transparent arm turn 107 is provided at the periphery of the color filter 350.
．． 108 and 109, this pattern is detected by the light receiving elements 111 and 112. Since the output of the light receiving element is either present or absent, if the relative angles of the three color filter sections 101, 102, 103 and the opaque segment sections 104, 105, 106 are accurately determined, the light guide Currently, the light incidence end 41 of 40 is
It becomes possible to know with high precision which part of the color filter 35 crosses. Therefore, the position of the three-color filter 35 is determined by the rotation speed of the filter and the light receiving element 111.
, 112, the image sensor timing circuit 81 is controlled by the digital tie Y/synchronizer generator aoVC, and the charge of the imaging section T1 is adjusted to the first
It is possible to generate a drive z4 pulse signal for transfer to the second storage part T2 and a drive/gust compensation code to control the line transfer to the second storage part γ3 and the signal output to the video processor T5.

For example, in FIG. 2, if the three-color filter 35 is rotated in the direction of the arrow and the transparent pattern 107 is at a position corresponding to the start of the red filter segment 101, then the light from the light-receiving elements 111 and 112 is There will be no output.

Therefore, digital timer/synchronizer generator 8
0 has a tricolor filter of 350 rotations and a video processor of 15
The video processor 75 receives signals corresponding to each color field from the solid-state imaging device 70 and identifies which color field is being operated.

When the three-color filter 35 rotates in the direction of the arrow, various colored lights sequentially enter the light incident end 41 of the light guide 40, and the distal end (not shown) of the endoscope main body 100 illuminates a cavity of the subject such as a body cavity. Become.

The imaging unit T1 of the solid-state imaging device 70 receives reflected light from the subject via a condensation optical system (not shown), receives red light for approximately 1/60 second, and transmits the amount of received light to each pixel of the imaging unit γ1. A charge corresponding to the amount is accumulated.

As the trichroic filter 35 continues to rotate in the direction of the arrow, the opaque segment 104 passes through the light input fRA 41 and the illumination light is blocked. During this so-called blanking period, the charge of the red field light accumulated in the imaging section 71 is transferred to the frame accumulation section 72 (first accumulation section) in response to a driving Noculus signal from the image sensor imaging circuit 81. .

Furthermore, during the period K from the time of incidence on the red filter segment 1010 for forming the red field to the time of completion of passing through the segment 1040, the blue field image signal previously stored in the first storage section 72 is sequentially transferred to the first storage section 72. The data is transferred to the storage unit (line storage unit) 73, and further transferred to the video processor T5. Video processor 75 receives a signal from digital timer/synchronizer 80 and transfers the blue field image signal to blue memory 79 via A/D converter T6 and switching circuit 91. Memories 17-19 shown in FIG. 1 are preferably dynamic random access memories (DRAMs) and each store a digital gator corresponding to one particular color field output signal from solid state imager 70. The switching circuit 62 is
It is controlled by a digital timer/synchronizer generator 8o, and transfer data from the A/D converter 76 is alternately stored in the memories 71-19.

As is clear from FIG. 1, this switching circuit 81 has D.
The output signal is transferred to RAMT T~7S and also directly to the output processor/encoder 90.

In the above condition, the blue component light of the subject is blue memo 1779.
K has been stored, and the next red component light has just been transferred to the first storage section T2. Next, green filter segment part 1
02 passes through the light input end 41 of the light guide 40 and the opaque segment portion 105 passes, the red field signal stored in the first storage is transferred to the second storage γ3 and further video The processor 75, A/D converter 76 and switching circuit 91 store the data in the red memory 77 and at the same time directly transfer it to the output grosser/encoder 90.

Further, the green field signal light is transmitted to the imaging section T1 of the solid-state imaging device.
The light is received and stored as a charge, and in the above-mentioned state, it is transferred to the first storage section T2.

As described above, during the blanking period in which each opaque segment portion 104 to 106 of the three-color filter 35 passes through the light incident end 41 of the light guide 40, the imaging section 7 of the solid-state image sensor 7o
The image signal of the previous color field accumulated in 1 is transferred to the first accumulation part T2, and the first accumulation is performed while one color filter segment and one opaque segment pass through the light entrance end 41. The data is transferred from the unit 72 to the second storage unit 73 and stored in one of the DRAM memories 17 to 79, and at the same time is directly transferred to the output grosser encoder 90.

Output processor encoder/9 (Nt, front two storage signals of DRAM memories 17 to 79 and switching circuit 91
By combining the signals directly transferred from the
or) generate a composite video signal such as an NT8C signal. One output of output processor encoder 90 is 1/
Since this is performed during a so-called one field period of 60 seconds, it goes without saying that it is also possible to prepare for yield use, since one frame of image reproduction can be realized by combining one set of memories together with the next one field period. stomach. The combination of color components of the three-color filter used the most traditional three primary colors of red, green, and blue; however, green, cyan, and yellow;
It goes without saying that combinations of cyan, magenta, yellow; green, red, cyan, etc. may also be used.

In addition, in the above explanation, frame transfer type CC
Although the description has been made using D as a solid-state image sensor, an interline type COD can also be used. In this case, the first
A vertical register is used as the storage section, and an output register is used as the second storage section, and the timing of the generation of the drive pulse from the image sensor timing circuit must also be adapted to this, but this is easy to do. It could be constructed as follows.

"Effect of the invention" According to the configuration of the present invention as described above in detail.

The color light forming part and the non-color light forming part of the rotary filter to obtain a field sequential color light line are skillfully oriented to transfer the necessary image signals, so that the field sequential system is extremely efficient and waste-free. The effect is that it is possible to provide an endoscope that can perform imaging and has excellent performance without causing a decrease in the sensitivity of the solid-state image sensor.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of an embodiment of the present invention, and FIG. 2 is a plan view of a rotating trichromatic filter. 70... Endoscopic f11 main body, 20... Control unit, 35... Three-color filter, TO... Solid-state imaging device, T1... Imaging unit, 72... First storage unit, T3 . . . second storage section, 101-103 . . . colored light forming portion, 104-106 . . . non-colored light forming portion.

Claims (2)

[Claims] (1) In an endoscope that is attached to an endoscope and has a solid-state image sensor that converts image light obtained through the endoscope optical system into an electrical signal, illumination that guides light from the outside to illuminate the subject. A rotating three-color filter is arranged between the light input end of the light guide and the light source, and the object to be examined is sequentially illuminated with three colored lights in time series, and color image signals corresponding to each color field are transferred to the solid-state imager. The rotating three-color filter is divided into a light-forming portion for each color and a non-color light-forming portion so as to be taken out from the element, and when the non-color light-forming portion crosses the light incident end during rotation of the rotating three-color filter. , an endoscope configured to transfer an image signal captured by the solid-state image sensor to an image signal storage section. (2) A second image signal storage section is connected to the image signal storage section, and during rotation of the rotating three-color filter, one color light forming section and a non-color light forming section connected thereto are connected to the light incident end. 2. The endoscope according to claim 1, wherein when crossing the endoscope, one field worth of color image signals accumulated in the image signal accumulation section is transferred to the second image signal accumulation section.