JP2644991B2 - Endoscope device - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to an endoscope apparatus for observing a living body or a mechanical structure by invading a visual part and a lighting part.

[Technical Background of the Invention] As shown in FIG.
Is illuminated by the light guided by the optical transmission path 50. Optical transmission line 50
Is a bundle of about 10,000 optical fibers. The base of the optical transmission path 50 is attached to the light source control unit 51. In the light source control unit 51, a light source 52 and a diaphragm device 53 are provided.
Are arranged. The aperture device 53 is for adjusting the amount of light input to the optical transmission path 50, and can be manually adjusted. As the light source 52, a halogen or xenon light source is used.

Light from the subject 11 enters the image fiber 55 via the objective lens 54. The image fiber 55 is an optical fiber having a diameter of about 10 to 50 μm
About 5,000 are bundled. Image fiber 55
Guides the image light to an external eyepiece 56.

Here, the user observes the subject 11 through the eyepiece 56, and controls the aperture device 53 manually to adjust the illumination state. Manual squeezing is performed, for example, by operating a manual dial.

On the other hand, the video camera 57 may be used to observe the subject 11 in some cases. In this case, the adjustment of the light amount is generally performed by adjusting the aperture mechanism 57A of the optical system of the video camera 57. This is because it is necessary to always emit strong light from the light source in order to compensate for the loss of light amount of the optical fiber and the lack of sensitivity of the video camera.

The endoscope apparatus described above is used for observation of a digestive tract, a body cavity, a cylinder of an internal combustion engine, a water pipe, a nuclear reactor, and the like of a living body.

[Problems of Background Art] According to the above-described conventional endoscope apparatus, light from a subject is once guided to the outside of an object, observed with the naked eye, or captured with a video camera.

Therefore, an outgoing optical path and a return optical path are required. For this reason, there is a problem that the loss of the light amount is large, a strong light source is required, and there is a problem that a thermal influence caused by the strong light adversely affects the observation target.

In addition, optical fibers tend to attenuate short-wavelength region light (blue light) due to the nature of the material. Therefore, when the light emitted from the light source reaches the subject, the light becomes redder than the light actually emitted by the light source itself. Furthermore, since the reflected light from the subject is guided to the observer's eyes by the optical fiber, a more reddish image is captured by the observer, and the image is observed as being different from the actual color tone.

Furthermore, since the optical fiber is used by inserting it into a narrow space of the object to be observed, there is a limit in increasing the number of optical fibers, and there is a problem that the resolution is low when a video camera is used.

In addition, in order to adjust the amount of light from the light source 52, it is necessary to manually adjust the light amount in any case.

[Object of the Invention] The present invention has been made in view of the above circumstances,
(A) the light collection rate of light from the subject is high, the power of the light source can be relatively small, (b) the diameter of the cable inserted into the observation object can be reduced without deteriorating the resolution, and (c) the object is irradiated. It is an object of the present invention to provide an endoscope apparatus having an appropriate color tone without impairing the light component to be emitted.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
It is illuminated by light from the light transmission path 12. The reflected light from the subject 11 is imaged on the photosensitive surface of the imaging device 14 close to the objective lens 13 and the second light correction filter 17 on the imaging device side. Here, the image pickup device 14 has a complementary color filter described later. Here, the light correction filter 17 has such a characteristic that the output of the image sensor 14 becomes standard with respect to the illumination light of 5500K, and is formed of, for example, a phosphate glass cyan filter. The image signal read from the image sensor 14 is guided to the outside of the object via the signal transmission line 16 and supplied to the signal processing circuit 22 in the observation controller 20. A drive circuit 21 is provided in the observation control unit 20, and a drive signal from the drive circuit 21 is supplied to the image pickup device via a drive line 15.
Is supplied to 14.

On the other hand, the base of the optical transmission line 12 is also guided into the observation control unit 20, and its end faces the automatic aperture device 33 via the first light correction filter 36. The automatic squeezing device 33 includes, for example, racks 29 and 30 and a pinion 2 that drives each rack.
Xenon light source 31 is opposed to the gap formed by racks 29 and 30. FIG. 5 shows the emission spectrum of the xenon light source. (See page 238 of the Color Science Handbook published by Tokyo Denki University Press). The first light correction filter 36 has a function of correcting a Cologne-like component included in the emission spectrum of the xenon light source 31 so as to approximate a blackbody radiation spectrum of about 5500K. Reference numeral 32 denotes a reflecting mirror that condenses the light of the light source on the end of the optical transmission path through the gap.

The gap of the automatic aperture device 33 can be freely enlarged or reduced by rotation of the motor 26. Further, the motor 26 responds to the output obtained by integrating the luminance signal obtained by the signal processing circuit 22 by the integration circuit 24, that is, the output of the integration circuit 24 is supplied to the motor drive circuit 25, and the motor drive circuit 25
Generates a drive pulse corresponding to the value of the integration output,
The shaft of the motor 26 rotates at a rotation angle corresponding to the number. In this case, a fixed association is established between the value of the integral output and the rotation angle (aperture amount) of the motor 26. When the integral value exceeds a reference value, the aperture is reduced, When the integrated value is lower than the reference value, control for increasing the aperture is performed. Further, depending on the observation object, the integration circuit 24 may have a small reference value or vice versa. Therefore, a reference value changing means 24A is connected to the integration circuit 24.

As described above, according to this endoscope apparatus, under the illumination of 5500K, the output of the image sensor is set to the standard state under the illumination of 5500K using the second correction filter 17, so that the illumination is not performed under sunlight or fluorescent lamp illumination. Appropriate color reproduction can be obtained. In addition, the first correction filter 36 makes the emission spectrum of the xenon light source capable of obtaining high luminance close to 5500K, so that even when imaging an object in a dark sinus, the coherent light included in the emission spectrum of the xenon light source is used. The poor color reproduction due to the light component having the peak of (1) is remarkably improved, and the color reproducibility is kept good. Further, the amount of light applied to the subject 11 can be automatically adjusted so as to be an optimal amount for imaging. In addition, since the image pickup device 14 has a structure in which the image pickup device 14 is brought close to the subject, the optical transmission path may be only the outward path, and the loss of the light amount is remarkably small as compared with the related art. This effect becomes more significant as the transmission path becomes longer. Of course, if the optical fiber length is changed, the spectral transmission characteristics of the optical fiber are changed. Therefore, the characteristics of the first, second, or both optical correction filters are changed according to the change in the optical fiber length, so that the output of the image sensor changes with respect to the color signal. What is appropriately adjusted so as to obtain a desired ratio may be used. On the return path, there is no optical fiber as in the related art, but only a signal transmission line. Therefore, the diameter of the cable to be inserted into the object can be made smaller than before. Further, since the video signal from the output terminal 23 has a luminance level automatically adjusted to a predetermined level,
There is no need for the user to perform manual operation, and the efficiency of observation work can be improved. The video signal is reproduced by a monitor television receiver.

The present invention is not limited to the above embodiment, and various embodiments are possible.

FIG. 2 shows an electrochromic element as a diaphragm device.
35, which is controlled by an amplifier 34 that amplifies the integrated output. The electrochromic element is disclosed in, for example, Japanese Patent Application Laid-Open No. 56-4679. The other parts are the same as those in the embodiment of FIG.

FIG. 3 shows an example of a circuit for processing an image signal output from the image sensor 14.

The image sensor 14 has, for example, a color filter array as shown in FIG. In this filter, W, Ye,
Cy means transmission of the next color.

W: all colors (white) Ye: yellow Cy: cyan The imaging output of the imaging device 14 is W + W,
Ye + Cy, W + W,..., And at the (n + 1) th scanning line, W + Cy, W + Ye, W + Cy,.

The signal thus obtained is amplified by the amplifier 221 in the signal processing circuit 22 and supplied to the clamp circuit 222 so that the black level portion of the video is fixed at a certain DC voltage. Next, pre-blanking processing is performed by a pre-blanking processing circuit 223 in order to remove noise due to drive pulse jumps and the like included in the horizontal and vertical retrace periods and to create a wide and stable black signal reference. The modulated color signal is separated from the image signal thus obtained by the bandpass filter 224. This modulated color signal is applied to one horizontal line delay circuit 227,
The signal is supplied to a comb filter composed of an adder 228 and a subtractor 229, and separated into red and blue modulated color signals. The red and blue modulated color signals are supplied to a matrix encoder circuit 231 and converted into chroma signals. Further, the band of the imaging signal is limited to about 1 MHz by the low-pass filter 225, and is supplied to the matrix encoder circuit 231 as a signal for generating a color difference signal. Therefore, a color difference signal is obtained from the matrix encoder circuit 231 and supplied to the adder 232.
The luminance signal that has passed through the low-pass filter 226 is supplied to the adder 232. The adder 232 also adds a composite synchronization signal. Accordingly, a video signal is obtained from the adder 232, and the video signal is amplified by the amplifier 234 and output to the output terminal 23. This imaging method is described in, for example, "Prototype Production of Frequency Interleaved CCD Single-Chip Color Camera" 4-3 (pages 99 to 100), Proceedings of the 1983 National Conference of the Institute of Television Engineers of Japan. The output of the low-pass filter 226 is supplied to the integration circuit 24. As for the arrangement of the first and second optical correction filters, for example, the first optical correction filter 36 may be disposed on the image sensor side of the optical fiber 12. The first optical correction filter 36 is an optical fiber.
It may be manufactured integrally as a part of 12. Similarly, the second light correction filter 17 may be integrated with the image pickup device by bonding it or the like, or may be disposed between the objective lens and the subject. Although a light source and a xenon lamp have been described here as examples, a halogen lamp may be used. In that case, the light correction filter may be a color temperature correction filter that converts 3000K to 5500K. The standard illumination light of the image sensor is 5500K
It is not limited to.

[Effects of the Invention] As described above, according to the present invention, the light collection efficiency of light from a subject is high, and the power of a light source can be relatively small,
The diameter of the cable to be inserted into the observation object can be reduced without deteriorating the resolution, and good color reproducibility can be maintained.
In addition to this, the assembling accuracy is further increased, the optical axis is made accurate, and the imaging optical characteristics are improved. Since the gap is reduced,
This prevents dust from entering and eliminates the cause of image quality deterioration. Since the gap is reduced, the optical path is reduced, and the optical flare can be reduced. Since the optical filter can be formed to have an outer shape substantially equal to the imaging surface of the imaging device, the overall size can be reduced.

In addition, since the technology for making an image sensor has been advanced, an image having a large number of pixels (about 200,000) and a high resolution can be obtained.
By providing a color filter, a color image can be obtained with a normal halogen or xenon light source.

[Brief description of the drawings]

FIG. 1 is a structural explanatory view showing one embodiment of the present invention, FIG. 2 is a structural explanatory view showing another embodiment of the present invention, and FIG. 3 is a filter shown for explaining an example of a color imaging system. FIG. 4 is a diagram illustrating a configuration of a conventional endoscope apparatus, and FIG. 5 is a diagram illustrating an emission spectrum of a xenon light source. 11 subject, 12 optical transmission path, 13 objective lens, 14
…… Imaging device 15 …… Signal transmission line, 20 …… Imaging control unit, 22 …… Signal processing circuit 24 …… Integration circuit, 25 …… Motor drive circuit, 26 …… Motor 31 …… Light source, 33 …… Aperture apparatus.

Claims (2)

(57) [Claims] 1. An endoscope apparatus for illuminating a subject by guiding light from a light source through an optical transmission path using an optical fiber, wherein the input light provided between the light source and the subject has a spectrum of standard illumination light. A first light correction filter that outputs light closer to the object; an objective lens that forms an image of light from the subject; an imaging device that converts light from the objective lens into a video signal; A second optical correction filter disposed between the optical fiber and the optical signal so that the color signal of the image sensor is appropriately balanced with respect to the spectrum of the standard illumination light. An endoscope device integrated with a road. 2. An endoscope apparatus for illuminating a subject by guiding light from a light source through an optical transmission path using an optical fiber, wherein the input light provided between the light source and the subject has a spectrum of standard illumination light. A first light correction filter that outputs light closer to the object; an objective lens that forms an image of light from the subject; an imaging device that converts light from the objective lens into a video signal; A second light correction filter disposed between the second light correction filter and the second light correction filter to appropriately balance the color signal of the image sensor with respect to the spectrum of the standard illumination light, and integrating the second light correction filter with the image sensor. An endoscope apparatus characterized in that: