JPH029804B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an endoscope device used to observe the inside of a body cavity or a cavity such as a mechanical component. Conventionally, in such endoscopes, an optical fiber bundle guides an image of the object to be observed outside the body cavity or cavity, and the optical image formed on the output end face of the optical fiber is transmitted through the eyepiece system. I am observing it through. Another method is to install a solid-state imaging device at the tip of the endoscope sheath instead of the optical fiber, convert the optical image formed on the light-receiving surface of the solid-state imaging device into an electrical signal, and read the signal. It has also been proposed to lead the signal out of the body cavity or cavity using a wire, perform the necessary signal processing, and then display it on a TV monitor. In the endoscope described above, the information obtained from the object to be observed is limited to the visible light wavelength region.
In other words, in the former case, the image is viewed optically directly with the inner eye, so it is naturally impossible to observe anything outside the visible wavelength range, and in the latter case, the solid-state imaging device is also sensitive to the infrared wavelength range, so images in the infrared wavelength range cannot be observed. Although the information is detectable, when colorizing an image, image information in the infrared wavelength region becomes a hindrance to achieving color balance. Therefore, in order to improve color fidelity, it is common to use an infrared cut filter to prevent illumination light in the infrared wavelength region from irradiating the object to be observed, or even if it is irradiated, it does not reach the light receiving surface of the solid-state image sensor. It is necessary to install a filter to prevent this. When observing an image of an object to be observed using such an endoscope, it is necessary to detect subtle differences in color tone to distinguish between an affected area and a normal area, especially in a living body. Generally, detecting (recognizing) the difference requires a high degree of knowledge and experience, and it takes a long time to detect it, and requires concentrated attention during the detection. It is an object of the present invention to eliminate the above-mentioned drawbacks and to make it possible to quickly and easily distinguish between an affected area and a normal area. As a method for increasing the discrimination ability of an endoscope apparatus for observing affected and normal parts within a living body, the present invention adopts a method of converting invisible information obtained by infrared irradiation into visible information. As is generally known, solid-state imaging devices have high sensitivity in the near-infrared region. It is also known that illumination light sources generally emit more energy in the infrared wavelength region than in the visible wavelength region. By the way, the amount of light reflected from the object to be observed is red (long wavelength) in the visible light wavelength region in vivo.
The fact that it is more common on the side can be predicted from the red color of the blood. It has also been announced that the reflectance increases with near-infrared light. For these reasons, there is a good possibility that information obtained from infrared light in a living body is useful for extracting features in a living body. Image information obtained using infrared light in this way is displayed on a TV monitor in the color of a specific wavelength. Only images in different infrared wavelength ranges are displayed on the TV monitor (red), (green),
(blue), or those obtained in the visible light wavelength region (for example, a red image) and those obtained in the infrared wavelength region may be displayed simultaneously. In short, it is important to be able to extract image signals in a wavelength range that characterizes an affected area within a living body as a normal area. The endoscope apparatus of the present invention comprises: an illumination means for illuminating an object to be observed with light that includes at least an infrared region in a specific wavelength range of approximately 1200 nm or less; and a distal end of a portion inserted into the object to be observed. an optical system that is provided and forms an image of the object to be observed on an imaging plane by receiving reflected light from the object to be observed illuminated by the illumination means; A solid-state imaging device that converts an image of an object to be observed using only infrared light in a wavelength range into an electrical signal, and an electrical signal output from the solid-state imaging device that represents an image of an object to be observed using only infrared light in the specific wavelength range. The apparatus is characterized by comprising means for displaying an image in response to the received image. Next, the present invention will be explained in detail with reference to the drawings. Figures 1A and 1B show reflection spectra of human organs. Figure 1A is the spectrum of the stomach, where most
It is flat for wavelengths from 400 nm to 1200 nm, and its reflectance is several 10%. On the other hand, Figure 1 B shows the spectrum of blood, ranging from a few percent to 100% from 400 nm to 1200 nm.
It's changing in the near future. Comparing the two, it can be seen that the difference is particularly large in the infrared wavelength region (800 nm to 1200 nm). For example, if there is tissue that resembles blood or something that contains a large amount of blood in the stomach, and you try to recognize its existence,
It is clear that the difference is more pronounced when compared in the near-infrared wavelength region, and the effect is more significant. Current optical endoscopes can only observe and make judgments in the wavelength range of human specific luminous efficiency (400 nm to 700 nm). On the other hand, the sensitivity range of CCD extends from 400 nm to 1200 nm, which is sufficient to obtain information in the near-infrared wavelength region. Furthermore, light source lamps used as general light sources emit a large amount of energy in the near-infrared wavelength region rather than visible light. Irradiating an object to be observed with wavelengths in the near-infrared wavelength region requires only shifting the spectral characteristics of commonly used infrared light cut filters to longer wavelengths, and there is no technical difficulty in doing so. FIG. 2 shows the distal end of a portion of an example of the endoscopic device according to the present invention that is inserted into a body cavity. This example is a direct view type, and the light from the light source (see Figure 3) is transmitted to the light guide 1.
The object to be observed is illuminated through the illumination glass window 2. Reflected light from an object to be observed is taken in through an imaging glass window 3, and an image is formed by an imaging lens 4 on a light receiving surface of a self-scanning two-dimensional solid-state imaging device 5 such as a CCD or BBD. This solid-state imaging device 5
is a planar arrangement of a large number of photosensitive elements. The output signal is led out through the lead wire bundle 6. This lead wire bundle 6 also includes lead wires for supplying a clock signal for operating the solid-state imaging device 5 from an external oscillator (see FIG. 3). The light guide 1 and the lead wire bundle 6 are inserted into the sheath 7. Further, the lens 4 and the solid-state imaging device 5 are mounted in an outer case 8.
This is placed at the tip of the sheath 7. FIG. 3A shows the construction of one embodiment of the externally arranged part. A light source 21 is arranged opposite to the entrance end face 1a of the light guide 1 which projects from the end of the sheath 7. The light source 21 emits infrared rays and visible rays, and the rays emitted from the light source pass through a rotating filter 22 and enter the entrance end face 1a of the light guide 1, and are used as illumination light for the object to be observed. Since the core of the light guide 1 is generally made of multi-component glass, it is attenuated in the near-infrared wavelength region, so it is preferable to use a bundle made of fibers made of quartz or the like, which does not attenuate even in the near-infrared wavelength region, as the core material. . The rotary filter 22 is connected to the motor 20
It is arranged so that it rotates at a constant speed at a predetermined speed. The light-receiving element 24 and the color switching signal circuit 25 constitute a switching pulse generation circuit, which detects a passing wavelength range that changes depending on the rotation angle of the rotary filter 22, and generates a driving pulse for the solid-state imaging device 5 and a switching pulse generation circuit. Image signals etc. obtained from the imaging device 5 are synchronized with the rotation of the rotary filter 22. That is,
The light reflected by the half mirror 23 is made incident on a light receiving element 24, and the output of this light receiving element 24 is supplied to a color switching signal circuit 25. The color switching signal circuit 25 includes a current amplifier and a level detection circuit, and converts the output current signal of the light receiving element 24 into a voltage signal.
Level detection circuits create timing signals for each of the three lights (at least one including infrared light). Furthermore, the output of the current amplifier of such a color switching signal circuit is differentiated, and the levels are made uniform to be used as a trigger signal for the oscillation circuit 27. The signal switching circuit 28 receives the image signal led out from the imaging device 5 via the lead wire bundle 6 via the amplifier 26, and outputs it to each different output terminal in synchronization with the color type of light incident on the light guide 1. 2
8B, 28G and 28R. This signal switching circuit 28 uses a high-speed operating switch such as a semiconductor analog switch. The oscillation circuit 27 receives the trigger signal from the color switching circuit 25 and supplies a scanning signal for the imaging device 5 and a synchronization signal to the horizontal deflection circuit 32 and vertical deflection circuit 33 of the monitor cathode ray tube 34. The horizontal deflection circuit 32 consists of an output amplifier for deflecting the blue, green, and red beams of the monitor cathode ray tube 34 in the horizontal direction, and the vertical deflection circuit 33 consists of an output amplifier for deflecting these beams in the vertical direction. do. The green amplifier 2 is connected so that each output from the output terminals 28G, 28R, and 28B of the signal switching circuit 28 has a voltage sufficient to operate the green grating, red grating, and blue grating of the monitor cathode ray tube 34.
9, supplies to the red amplifier 30 and the blue amplifier 31, respectively. FIG. 3B is a diagram showing the configuration of still another embodiment of the externally arranged portion, in which 6' is a signal line from a solid-state imaging device, 35 is an amplifier, 36 is an A/D converter, and 37 is a rotating Switching circuits 38a, 38b and 38c that switch in synchronization with filter 22
39 is a memory that stores information for each wavelength region;
This is a TV signal processing circuit required for display on a TV monitor. In this example, information on three wavelength regions is stored in a memory 38 that is sequentially allocated to each wavelength region in chronological order.
When writing and reading data to a, 38b, and 38c, the signals are read out simultaneously to perform signal processing suitable for a TV monitor. The memories 38a, 38b, and 38c are provided with a refresh function to read out the same signal many times. Furthermore, each of the memories 38a, 38b, and 38c is composed of a plurality of memories, and can be written while being read. FIG. 4 shows rotary filter 22. FIG. The rotary filter 22 is equally divided into three parts 40, 41 and 42, for example, part 40 has a wavelength of 700 nm to 800 nm (red), part 41 has a wavelength of 800 nm to 900 nm (infrared region),
It is assumed that the portion 42 transmits light having a wavelength of 600 nm to 700 nm (orange color). The signal switching circuit 28 is driven in synchronization with the rotation of the filter 22, and, for example, an image signal obtained from the light transmitted through the red portion 40 is supplied to the green channel via the green output terminal 28G, and the image signal is supplied to the green channel through the green output terminal 28G. The image signal obtained by the light transmitted through the infrared region portion 41 is output to the red output terminal 2.
8R, the image signal obtained from the light transmitted through the orange portion 42 is displayed as a red image, and the image signal is sent to the blue output terminal 28.
B can be displayed as a blue image. In this case, the image signal obtained from each illumination light wavelength region is
It is not necessarily necessary to display the same color on the monitor cathode ray tube 34; for example, the output corresponding to the section 40 may be displayed in red, the output corresponding to the section 41 may be displayed in blue, and the output corresponding to the section 42 may be displayed in green. It is of course possible to display it. Although there are many combinations, these combinations may be used in such a way that the affected area and normal area can be most easily distinguished. Each part of the rotary filter 22 used in the present invention is
Various wavelength ranges can be set as shown in Table 1. However, the combination of wavelength regions is not limited to this. In this embodiment, the incident end surface 1a is circular, but it may be slit-shaped or rectangular.

[Table] In the example described above, the rotating filter 22 was provided in the illumination optical system and the object to be observed was sequentially irradiated with light in a predetermined wavelength range. It is also possible to illuminate the object to be observed with visible light including visible light, and to place a filter in front of the solid-state imaging device that selects light in a predetermined wavelength range. Next, some such examples will be explained. FIG. 5 is a diagram showing another embodiment of the filter 45 of the present invention. In this example, each wavelength-selective filter portion 45a, 4 is provided on the light-receiving surface of the solid-state imaging device.
5b and 45c are arranged in a checkered pattern, and at least one of the filter portions 45a, 45b and 45c is transparent only in the infrared wavelength region. For example, the filter portion 45a is R (red),
It is also possible to determine 45b as G (green) and 45c as IR (one of the infrared wavelength regions). The signal obtained from the solid-state image sensor is transmitted to a known single-panel color TV.
By performing processing similar to the signal processing of a camera, image signals corresponding to each wavelength region are separated, and signal processing that can display a color image on a TV screen is performed. FIG. 6 is a diagram showing an endoscope apparatus of the present invention incorporating the filter 45 shown in FIG. The light is made incident on the solid-state imaging device 5 through the . A signal from the solid-state imaging device 5 is supplied to a switching circuit 52 via an amplifier and a clamp circuit 51. This switching circuit 52 is synchronously driven by a solid-state imaging device drive circuit 53, and the filter 4
The signals obtained from each wavelength region of 5 are sequentially passed through the green, blue and red channel amplifiers and filters 5.
4a, 54b and 54c. These output signals are further supplied to a signal processing circuit 55,
A predetermined color signal suitable for a TV monitor can be obtained. FIG. 7 shows still another embodiment of the filter used in the endoscope apparatus of the present invention. The filter portions 46a and 46b of the filter 46 in this example constitute a so-called stripe filter 46 that transmits a red image signal and a green image signal, respectively. FIG. 8 is a side view showing an example of a photolysis system used in the endoscope apparatus of the present invention when the filter shown in FIG. 7 is used. In this case, two solid-state imaging devices 5a and 5b are used. That is, one solid-state imaging device is for obtaining an image signal in a specific wavelength range, and the other solid-state imaging device is for obtaining an image in another specific wavelength range or a plurality of wavelength ranges, and at least one of the wavelength ranges is It is characterized in that it is for obtaining an image in an infrared wavelength region. For example, light 9 reflected from an object to be observed and passed through a lens enters a pentaprism 10, where infrared wavelength region light is reflected by a dichroic surface 11, and red light and green light are transmitted and travel straight. The infrared wavelength region light 12 reflected by the dichroic surface 11 is reflected again by the mirror surface 13 and enters the first solid-state imaging device 5a via the infrared image transmission filter 47. dichroic surface 1
The light that has passed through the stripe filter 46 passes through the light-transmitting block 14 and passes through the filter portion 4 of the stripe filter 46.
Due to the filter action of 6a and 46b, red light and green light are transmitted through the second solid-state imaging device 5b.
incident on . FIG. 9 is a diagram showing an example of a configuration in which the photolysis system shown in FIG. 8 is incorporated into a portion of the endoscopic device of the present invention to be inserted into a body cavity. In this example, reflected light from an object to be observed is taken in through an imaging glass window 3, and an image is formed by an imaging lens 4, a pentaprism 10, a light-transmitting block 14, and solid-state imaging devices 5a and 5b. It is photolyzed and converted into electrical signals. The lead wire bundle 6 accommodates lead wires for taking out video signals from the imaging devices 5a and 5b, and the other structure is as shown in the explanation of FIG. 2. FIG. 10 is a reflection curve diagram of a normal part and an affected part in a living body cavity, where the reflection curve of the normal part is shown as A, and the reflection curve of the affected part is shown as B. Now, spectroscopy is performed using a spectroscopic filter that passes through each of the wavelength regions of l ₁ , l ₂ and l ₃ , and the electrical signals obtained from the solid-state imaging device using the light of each of these wavelength regions are, for example, R (red) and G, respectively.
When an image is displayed in synchronization with the (green) and B (blue) electrical signals, in the normal area, the reflection curve A traces a nearly flat trajectory, so the reflectance of R, G, and B is constant, and as a result, colors are mixed. It turns white. However, when looking at the affected area, if we draw a locus like reflection curve B and let the reflectances in the wavelength ranges l ₁ , l ₂ and l ₃ be α, β and γ, then αR + βG + γB
Because the colors are mixed at a ratio of In the visible range, even if it passes through a conventional visible range R, G, and B filter, reflection curve A and reflection curve B are almost the same, so the difference between normal and abnormal areas can be identified using a display device. It is difficult. The present invention is not limited to the above-mentioned examples, and can be modified and modified in many ways. Although the above example describes an example in which images in three wavelength regions are obtained, the present invention is not limited to this. Even more information can be obtained by using a large number of wavelength regions. In this case, the currently popular
On the TV monitor, R (red), G (green), B (blue)
The three primary colors are emitted, and images of various tones are displayed by mixing them, so it is possible to display a color image of three or more colors by mixing them, or by emitting light in each wavelength range. It is also conceivable to once transfer the image to a frame memory and then sequentially switch the image signals from the memory to read out the image signals in each of the three wavelength regions and display them in the three primary colors on the TV monitor. As described in detail above, according to the endoscope device of the present invention, it is possible to display an image of the object to be observed using only near-infrared light, so that tissue resembling normal blood or a large amount of blood can be displayed. It is possible to obtain an image that shows the affected area, which is the tissue that contains it, in high contrast with the normal area, and it is also possible to see the condition of the subcutaneous tissue, making it possible to easily and accurately distinguish between the affected area and the normal area. It is something.

[Brief explanation of drawings]

1A and 1B are views showing the state of the reflection spectra of human organs, FIG. 2 is a sectional view showing the tip of the endoscope device according to the present invention inserted into a body cavity, and FIG. 3A is a diagram showing the state of the reflection spectrum of human organs. and B are diagrams showing the configuration of parts arranged outside the device of the present invention, respectively, and FIG. 4 is a diagram showing a rotating filter used in the device of the present invention,
FIG. 5 is a diagram showing a modified example of the filter, FIG. 6 is a configuration diagram showing an example of the use of the filter in FIG. 5, FIG. 7 is a diagram showing still another example of the filter, and FIG. A side view showing an example of the photolysis system used in the device of the present invention when using the filter shown in FIG. FIG. 10 is a diagram showing a typical configuration example, and is a diagram showing reflection curves for a normal part and an affected part in a living body cavity. 1... Light guide, 2... Glass window for lighting, 3...
Imaging glass window, 4...imaging lens, 5, 5a,
5b...Solid-state imaging device, 6...Lead wire bundle, 6'
...Signal line from the solid-state imaging device, 7...Sheath, 8...
... Outer case, 9 ... Light passing through lens, 10 ... Pentaprism, 11 ... Dichroic surface, 12
...Infrared wavelength region light, 13...Mirror surface, 14...
...Light transparent block, 20...Motor, 21...
Light source, 22... Rotating filter, 22a... Optical filter, 23... Half mirror, 24... Light receiving element, 25... Color switching signal circuit, 26... Amplifier,
27...Oscillation circuit, 28...Signal switching circuit, 28
R...Red output terminal, 28G...Green output terminal,
28B...Blue output terminal, 29...Green amplifier,
30...Red amplifier, 31...Blue amplifier, 32
...Horizontal deflection circuit, 33...Vertical deflection circuit, 34
... Monitor cathode ray tube, 35 ... Amplifier, 3
6... A/D converter, 37... Switching circuit, 38a, 38b, 38c... Information storage memory, 39... TV signal processing circuit, 40, 41, 4
2, 45a, 45b, 45c, 46a, 46b...
...Filter portion, 45, 46, 47...Filter, 51...Amplifier/clamp circuit, 52...Switching circuit, 53...Solid-state imaging device drive circuit, 54a, 54b, 54c...Signal amplifier/filter, 55... ...Signal processing circuit.

Claims (1)

[Scope of Claims] 1. An illumination means for illuminating an object to be observed with light that includes at least an infrared region in a specific wavelength range of approximately 1200 nm or less; , an optical system that receives reflected light from the observed object illuminated by the illumination means and forms an image of the observed object on an imaging plane; and an optical system that is disposed at the imaging plane position of this optical system and is arranged in the specific wavelength range. a solid-state imaging device that converts an image of an object to be observed using only infrared light into an electrical signal; and a solid-state imaging device that receives an electrical signal representing an image of an object to be observed using only infrared light in the specific wavelength region outputted from the solid-state imaging device. What is claimed is: 1. An endoscope apparatus comprising means for displaying an image.