JPS58214114A - Endoscope focusing detector - Google Patents

Abstract

PURPOSE:To ensure the focusing detection with high accuracy in a state under which the observation is possible, by using the light of a specific wavelength for focusing detection and shielding a specific wavelength of the illumination light for observation or diagnosis. CONSTITUTION:An endoscope 1 consists of an inserting part 2 containing an illumination optical system and an objective optical system for observation at its tip, a control part 4 including a light guide metal cap part 3 and an eyepiece 6. An eyepiece lens 5, a photographing lens 14 which slides on an optical axis 13 and a camera main body 12 are attached via a semitransparent mirror 15 to an adaptor 11 which is attached to the eyepiece 6. The focusing detecting wavelength is cut off via a filter 41 within a light source device 8 and transmitted to a light cable 7. While a focusing detecting light source 19 projects only a specific wavelength to a subject 10 through a filter 17 and via the mirror 15. Then the focus state is detected on a photoelectric surface 22 containing a pinhole 21.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses light of a specific wavelength for focus detection, and uses a filter or the like to prevent the specific wavelength of illumination light for observation or diagnosis from being transmitted. The present invention relates to a focus detection device for an endoscope that can perform focus detection with high precision in an observable state.

In recent years, endoscopes have been widely used in the medical and industrial fields. Particularly in the medical field, in addition to directly observing and diagnosing internal organs within the body cavity by placing the eye close to the eyepiece of the endoscope, cameras, television cameras, etc. are attached to take photographs for the purpose of diagnosis. It is widely done and recorded.

In the above case, when observing with the naked eye, the operator can adjust his or her diopter to form a clear optical image, that is, bring it into focus (focus point), but the camera, When a photographic device such as a television camera is attached, the photographic lens must be adjusted to a focused point in order to take clear photographs. In order to bring the photographic lens into focus, it is desirable to have a means that can clearly detect whether or not it is in focus.

In general, the observation optical system of an endoscope is warmer and darker than the observation or photographing optical systems of other optical devices, and it may not be in focus when photographing at a close distance.
There is a problem in that the depth of focus is shallow, which tends to result in so-called blurry photographs.

For this reason, there are cases in which images cannot be taken of lesions that change from moment to moment, resulting in the problem that the camera cannot be used with confidence.

On the other hand, when detecting whether the focus is in focus using a focus detection means in an endoscope, light is emitted for focus detection, and the light is reflected back from the subject for focus detection (or distance measurement). When performing focus detection by receiving light from the camera (for use with other cameras), widely diffused illumination light for observation or collation was received along with the light for focus detection, making it impossible to accurately detect focus. .

The present invention has been made in view of the above-mentioned points, and the present invention performs focus detection by projecting light of a specific wavelength for focus detection, and during this time, the specific wavelength of the illumination light for observation or diagnosis is emitted. It is an object of the present invention to provide a focus detection device for an endoscope that can accurately detect focus in a state that does not hinder observation by preventing only the light from passing through a filter or the like.

The present invention will be specifically described below with reference to the drawings.

FIG. 1 and FIG. 2 relate to a first embodiment of the present invention.
The figure shows the first embodiment, and FIG. 2 shows an example of the light receiving means used in the first embodiment.

In FIG. 1, a rigid endoscope 1 has an illumination optical system and l! An elongated insertion section 2 in which an objective optical system for observation is disposed, and an operation section (grip section) 4 having a large diameter on the rear end side of the insertion section 2 and a light gyroscope metal section 3 on the side. , and an eyepiece section 6 housing an eyepiece lens 5 at the rear of the operation section 4. A light guide cable 7 is connected to the light guide metal part 3 formed on the side of the operation section 4, and a light guide cable 7 is connected to the outside. Illumination light is supplied from a light source 8.

The insertion section 2t is inserted into the abdominal wall 9, etc., and the optical image formed by the internal objective optical system is transferred to the relay optical system at a distance suitable for observing the target internal organ (subject) 10. Observation or 11ii shadowing can be performed from behind the eyepiece section 6 via an image transmission means such as a system. The eyepiece section 6 is equipped with either the front end side of the adapter 11 (for photographing) or @
A detachable camera (main body) 12 is further attached to the rear end side of the adapter 11.

Inside the adapter 11, on the optical axis 13 behind the eyepiece 5 in the endoscope 1 when attached, there is a photographing lens 1 that can be manually moved back and forth on the optical axis 13 as shown by a dashed line.
4, and on the optical axis 13 further behind this photographic lens 14, there is a semi-transparent I that is inclined (for example, 45 degrees inclined) to the optical axis 13.
T! A focusing mirror 15 formed of a half mirror is provided.

A re-imaging lens 16. The light incident along the optical axis 13 is reflected by the focusing mirror 15 on the reflected optical axis (in the upper position in FIG. 1). A filter that passes only light of a specific wavelength 17.
A light receiving element 18 as a light receiving means, a light source 19 for focus detection
are arranged in sequence.

The light-receiving element 18 constituting the light-receiving means has a pinhole 21 (or slit-shaped square hole) in the center as shown in FIG.
It has a disk shape (of course, it can be square or rectangular) with openings such as , etc., and the entire surface of this disk is incident on the PN junction surface of a photosensitive element, such as a photodiode, phototransistor, etc. A photocathode 22 is formed of an element whose current characteristics change depending on light, an element that generates a photovoltaic force like a solar cell, an element whose resistance value changes like a CDS, etc., and a light shielding surface 23 is formed on the back side of the photocathode 22. is formed so that the light receiving element 18 is not directly exposed to light from one light source for detecting focus at a position behind (above in FIG. 1) the pinhole 21.

On the other hand, the camera 1 attached from the rear of the adapter 11
2, a return mirror 24 is disposed on the optical axis 13 behind the focusing mirror 15 and inclined (for example, 45 degrees) to the optical axis 13, and a photographic film 25 is disposed behind the return mirror 24.
is installed.

On the reflected optical axis of the return mirror 24 (upper in the illustration)
A pentaprism 26 is disposed on the optical axis of the pentaprism 26, which inverts the left and right sides and returns the image to an erect image.
It is configured so that an optical image equivalent to that formed on the surface of the film 25 can be observed. The return mirror 24 is configured to retreat during photographing so that the incident light is imaged on the surface of the film 25.

The position of the photocathode 22 of the light receiving element 18 is arranged to be conjugate with the position of the surface of the film 25.

That is, the optical path length when the light passing through the lens 14 is imaged on the rear film 25 surface, and when it is reflected by the focusing mirror 15, the light passes through the reunion lens 16 onto the photocathode 22 of the light receiving element 18. The optical path lengths are set to be equal when images are formed.

On the other hand, the power supplied to the light source device 8 via the power source 32 provided with the N source plug 31 is transformed by a transformer 33 housed in the light source device 8, and is supplied to the control circuit 34 as AC power of a predetermined voltage. It is configured to provide the following. The power cord 32 turns on the power supplied through the cord 35 in the optical S device 8 by operating the power switch 36.
It is configured so that it can be turned off.

The light from an illumination light source (lamp) 37 attached to a lamp stand 37' disposed in the light source device 8 is transmitted to a connector receiver provided on the outer periphery of the light 'a@@B at a position facing the light source 37. It is installed by inserting it into the 39 (Limy Gaitou)
-The light is projected onto the (incidence) end face 40A of the connector 40 (of the pull 7), and is transmitted through the light guide group 7 to the inner ? ff I
The light is transmitted to the guide rod metal part 3 of I, and further the endoscope 1
The subject 10 in front of the insertion section 2 is
It is configured to project light to the side.

A filter 41 that does not transmit only light of a specific wavelength can be interposed between the light source 37 and the end surface 40A of the connector 40 that is irradiated with the illumination light (inspection light) of the light source 37. There is.

That is, a knob 42 formed on the outer periphery of the light source device 8 has a rotatable V, and a knob 4 is attached to the outer end of a shaft 43 mounted thereon.
4 is attached (pull). Then, by rotating the knob 44, the light shielding plate 45 attached to the inner end side of the shaft 43 is rotated, and the light 137 and the end face 40A of the connector 40 are rotated. The filter 41 fixed to the opening formed in the light shielding plate 45 located between the filter 41 is rotated and retracted from the illustrated position so that the illumination light that has passed through the filter 41 does not pass through the filter 41. , is configured to directly irradiate the end surface 40A of the connector 40.

Note that the output from the light receiving element 18 is determined by a focus detector using a comparator or the like as to whether or not the output is in focus. This can be done, for example, by inputting the output of the light-receiving element 18 into one input terminal of the comparator, and setting the reference level corresponding to the dark current level (minimum value level) into the other input terminal. Whether the polarity is reversed or not can be used to detect whether or not the lens is in focus. In this case, a buzzer or an LED or lamp may be turned on in the finder.

In the first embodiment configured in this way, the light source 19 used for focus detection is projected onto the subject 10 by the filter 17, passing only a specific wavelength, such as a hue that does not exist in the human body, such as a wavelength such as green. On the other hand, the first embodiment is characterized in that the illumination light for observation or diagnosis is configured so that only the specific wavelength is not transmitted through the filter 41.

The operation of the first embodiment of the present invention configured in this manner will be described below.

Connect the power plug 31 to a commercial power outlet, etc., and operate the switch 36 to turn on the power.

The insertion section 2 of the endoscope 1 is inserted into the abdominal wall 9 or the like through a trocar, and set at a position where a subject 10 such as a lesion can be observed.

Adapter 11 to endoscope 1. Furthermore, a camera 12 is attached,
Observe the illuminated subject 10. Subject 1 in this case
0 indicates that the illumination light m37 is illuminated with the filter 41 cutting off only the light of a specific wavelength used for focus detection, and the cut wavelength is removed by the light 8Pi19 for focus detection. Since the object 10 is also illuminated by light, the viewer can fully observe the object 10. In this case, the light of the specific wavelength from the focus detection light source 19 passes through the photographic lens 14 and hits the subject 10 from 1 to 3.
Since the light of the specific wavelength reflected by the subject 10 is received by the light receiving element 18,
When the lens 14 is moved and the focus is reached, the light receiving element 18
Since the output level becomes the dark level, it is possible to detect that the image is in focus.

Note that the operation detected from the output of the light receiving element 18 depending on whether or not the above-mentioned in-focus state is achieved is as follows.

As shown in FIG. 1, for example, when the subject 10 is at the position already shown and the lens 14 is clearly focused on the surface of the film 25, in this case, a spot is emitted from the light source 19. The position where the light that is projected onto the object 10 and reflected by the object 10 at the position of the symbol is focused on the optical axis reflected by the focusing mirror 15 is the position of the pinhole 21.
Since no light reaches the photocathode 22, its output is at a level equivalent to the dark current.

On the other hand, when the lens 14 is in focus at the above-mentioned point, the image formation position for the object 10 (indicated by the sign a in the figure) located behind (at a close distance) is the pinhole 21.
The light is received by the photocathode 22, and the output level corresponds to the amount of light received. Similarly, when the lens 14 is in focus, the imaging position of the object 10 (indicated by C in the figure) located ahead (far away) will be in front of the position of the pinhole 21. Since it expands backward from that position, the photocathode 22
The light will be received by the In other words, the level corresponds to the dark current, which is the minimum value or minimum value when in focus.
If it is out of focus, both values will be larger than that value, so
As mentioned above, if a comparator or the like is used, it is possible to detect whether or not the object is in focus.

In the focus detection described above, the light from the light source 19 used for focus detection is filtered to a specific wavelength only, and this light is projected onto the subject 10, while the light of this wavelength is used for illumination. Since the light emitted from the light source 37 toward the subject 10 is filtered by the filter 41, highly accurate focusing can be achieved without being affected by external light, which deviates from the paraxial ray and becomes a noise component for focus detection. Focus detection becomes possible. In addition, since the illumination light cuts only light of a specific wavelength, observation can be performed without any trouble.

In this focused state, when a release button (not shown) is pressed, the shutter opens, and when the automatic exposure mechanism of the camera 12 operates to provide proper exposure, the shutter closes and a photograph is taken.

Note that the filter 17 may be placed in front of the lens 16.

FIG. 3 shows a second embodiment of the invention.

In this embodiment, the light source 19 for focus detection in the first embodiment is not housed within the adapter 11, but is provided within the light source device 8.

Therefore, in the light source device 8, the illumination light [37, filter 41 . In addition to the connector receiver 39, a focus detection light source (Racip) is attached to the lamp stand 51'.
51. Further, connector receivers 53 arranged in front of the light source 51 are arranged side by side so as to cover the light source 51 adjacently. The other end of the light guide cable 55, which has a connector 54 attached to the connector receiver 53 at one end, is attached to a light guide fitting 56 protruding from the adapter 11, and the other end of the light guide cable 55 is attached to the light guide fitting 56 that projects from the adapter 11. Light is transmitted and supplied to the adapter 11 side, and is configured to be emitted from the inner end surface of the light guide metal part 56 through an opening such as a pinhole 21 formed in the light receiving element 18.

The filters 17 and 41 in this second embodiment exhibit transmission characteristics that are complementary to each other. For example, the filter 1
When filter 7 passes only green, the other filter 41 exhibits a transmission characteristic that allows wavelengths other than that (green) to pass. In this case, it goes without saying that the specific wavelength may be a single wavelength (range), a plurality of wavelength ranges, or a distributed wavelength range.

Similar to the first embodiment, the effect of this embodiment is that the filter 17 prevents the widely diffused illumination light used for illumination from entering the focus detection side, resulting in highly accurate focusing. Detection becomes possible. Further, since sufficient illumination light is projected onto the subject 10 side, sufficient observation can be made. Furthermore, in this embodiment, a focus detection light source 51 is provided in the light source device 18.
, it is possible to emit a sufficient amount of focusing light in a spot without making the adapter 1.1 bulky, so the detected signal output is large and more accurate focusing can be achieved. Detection can be performed.

FIG. 4 shows a third practical example in which the light source 51 for focus detection in FIG. 3 is also used as illumination light 837.

That is, a half mirror 57 is disposed at an angle between the illumination light source 37 and the filter 41 in front of it, and the illumination light is reflected by the half mirror 57 and reflected by the condenser lens 581 on the optical axis. Mirrors 59 are arranged in sequence, and the light reflected by the reflecting mirrors 59 is configured to be irradiated onto the end surface 54A of the connector 54 of the light guide cable 55 for transmitting focused light. The other parts are the same as those in the second embodiment.

According to this embodiment, the half mirror of the illumination light for observation
The light that has passed through 57 is transmitted through the filter 41 except for the light of a specific wavelength used for focus detection, and is transmitted to the light guide cable 7 to the light guide metal part 3.
Furthermore, the illumination light is projected onto the subject 10 side through the illumination light transmission means within the endoscope 1.

On the other hand, a portion of the illumination light is reflected by the half mirror 57, condensed by the lens 58, further reflected by the reflection mirror 59, and irradiated onto the end surface 54A of the connector 54, and then passes through the light guide cable 55 to the adapter 11 side. The light is transmitted, passes through the pinhole 21 of the light-receiving element 18, is transmitted by the filter 17, and is further reflected by the focusing mirror 15, passes through the lens 14, etc., and is illuminated in a spot on the subject 10 side. be done. By measuring the light projected in spots by the light receiving element 18, it is possible to detect whether or not the object is in focus.

Therefore, the effect is almost the same as that of the second embodiment, but
Compared to the second embodiment, only one light source 37 is required.

FIG. 5 shows a fourth embodiment in which the collimation light and the distance measurement light are separated by a mirror.

That is, in this embodiment, a spectroscopic mirror 61 is used in place of the filter 41 and half mirror 57 in the fourth embodiment. This spectroscopic mirror 61 has a transmission (reflection) characteristic of selectively reflecting only light of a specific wavelength and transmitting light of other wavelengths.

The other parts are the same as those in the third embodiment.

This embodiment has almost the same effect as the third embodiment, but since the illumination light and distance measurement light are effectively separated by the spectroscopic mirror 61, the light divided by the l\-7 mirror 57 is Furthermore, the light can be projected toward the subject 10 more efficiently than in the third embodiment in which the light is separated into predetermined light through each filter 17.41, which is advantageous for observation and focus detection.

Figure 6 shows the 5th filter with a filter installed on the light guidero metal part.
An example is shown.

In this embodiment, as shown in FIG. A filter 72 is disposed near the light guide metal part 71 (No. 7).

That is, as shown in an enlarged view in FIG. 7, a filter 72 that passes light other than a specific wavelength used for focus detection is disposed on the end face of the light guidero metal part 3. It is fixed by a filter holding member 73 that is screwed onto the metal part 3, and the LightGytro metal part 71 can be attached to the filter holding member 73 screwed to the LightGytro metal part 3 by screwing or the like. has been done.

On the other hand, the filter 17 disposed within the adapter 11 passes only specific wavelengths, as described above.

This embodiment has almost the same effect as the first embodiment, but
This embodiment has the advantage that it can be configured to have the same function as the first embodiment by using the filter nia 2 and the filter holding member 73 without modifying the light source device 8.

This embodiment can be configured to be provided in the middle of the light guide cable 7, or the light guide cable 7
It is also possible to use a plurality of light guide cables, and to insert the filter 72 in a member to which the plurality of light guide cables are connected.

In each of the above-mentioned embodiments, a single wavelength such as green is preferable as the specific wavelength for focus detection (distance measurement) from the viewpoint of photographing, but wavelengths covering a plurality of wavelength ranges can also be applied. In this case, it is more effective to use light with a wavelength that does not match the color tone of the subject 10 as the focus detection light.

In addition, in the above, a light of a specific wavelength is used as the light projected in a spot for focus detection, while light of a wavelength other than the above is used as the light projected for collation. However, the light emitted for focus detection may include at least a specific single wavelength, while the light emitted for collation may include the above-mentioned light. All devices that do not use light with wavelengths that include some or all of these wavelengths fall within the scope of the present invention.

For example, one example of the above is a case where white light excluding the green and blue wavelength ranges is used as the collation light, while green light is used when the wavelength range is not used.

In addition, if a light receiving means that is selectively sensitive to only a specific wavelength used for focus detection is used, the filter 17
At the rear of the light receiving element 18, the light is +1119 or 51.
It is also possible to place it in front of 37.

Note that the filter 41 disposed within the light source device 8 may be configured to be evacuated in the case of i-shadow as in the first embodiment. In this case, it is also possible to configure the evacuation to be performed automatically instead of manually.

As described above, according to the present invention, light for focus detection,
Since it is configured to use light in a wavelength range different from that of the illumination light, it has the advantage that focus detection can be performed with high accuracy with a simple configuration without causing any trouble to observation.

[Brief explanation of drawings]

1 and 2 relate to a first embodiment of the present invention, FIG. 1 is an explanatory diagram showing a schematic configuration of the first embodiment, and FIG.
FIG. 3 is an explanatory diagram showing the general structure of the second embodiment; FIG. 4 is an explanatory diagram showing the general structure of the third embodiment; FIG. is an explanatory diagram showing the general configuration of the fourth embodiment, FIGS. 6 and 7 are related to the fifth embodiment, FIG. 6 is an explanatory diagram showing the configuration of the fifth embodiment, and FIG. FIG. 5 is an enlarged cross-sectional view showing the main parts around the light guide metal part in the fifth embodiment. DESCRIPTION OF SYMBOLS 1... Endoscope, 6... Eyepiece part, 7... Light guide cable, 8... Light source device, 11... Adapter,
12... Camera, 13... Optical axis, 14... Lens, 17... Filter, 18... Light receiving element, 19...
・Light source, 21... Pinhole, 22... Photocathode, 2
5... Film, 37... Light source, 41... Filter, 51... Light source, 53...] Connector holder, 55...
...Light guide cable, 56...Light guidero metal part, 57...Half mirror 158...Lens, 5
9...Reflection mirror, 71...Light Gytro metal part,
72...filter, 73...filter holding member. Continued from page 1 0 Inventor Shin Kato - 2-43-2 Hatagaya, Shibuya-ku, Tokyo Lymphus Optical Co., Ltd. 0 Inventor Susumu Takahashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Lymphus Optical Inventor: Akira Nakamura, 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inventor: Akifumi Ishikawa, 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inventor: Akifumi Ishikawa Uchite Co., Ltd. (Self-funded) May 1980
May 30th, Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1, Issue 1'1, Showa 5) 7th Patent Application No. 096532, 2, Title of Invention: Endoscope Focus Detection Device 3, Amendment 4 Case Related Patent Applicant Representative Name: Shigeru Kitatori In column 1 of the brief explanation of the drawings specified by the specification, and lines 18 and 19 of page 7 in the column 1 of the detailed explanation of the invention specified by Akira ms, it is stated that “...・The sentence "On the optical axis where this pentalism 26 is reflected..." is corrected to "...On the optical axis where this pentalism 2 is reflected...". 2. In the column for a brief explanation of the drawings of the Ming I, the 11th line of page 22 has changed from ``...reflecting mirror, 71...rai 1-guy'' to ``...reflecting mirror, 61...
Spectral Mirror, 71...Light Guy" is corrected. that's all

Claims (3)

[Claims] (1) Illumination light transmitted from an external illumination light source through lie 1 to the guide is irradiated onto the subject through an illumination light transmission means disposed inside, and the irradiated subject is observed using an observation optical system. It is attached to an endoscope that can be observed through the imaging system, and the charging surface is used to detect whether the optical image of the subject is in focus or not. In an endoscope focus detection device capable of detecting whether an optical image of a subject is in a focused state that is clearly formed on a predetermined imaging plane by photometry with a light receiving means, the illumination light is A means for selectively not transmitting light containing at least a specific single wavelength in the middle of the illumination light projected to the subject side via the transmission means, and a part or part of the light containing at least the specific single wavelength. It is characterized by having means for selectively transmitting light of a specific wavelength including the entire area and projecting the light to the subject side through a lens, and selectively receiving the projected light of a specific wavelength. A focus detection device for endoscopes. (2) The means for selectively not transmitting light containing at least a specific single wavelength is provided in the filter or half mirror 1 disposed in front of the collation light source, near the end face of the light guide, or in the middle of the light guide. The focus detection device for an endoscope according to claim 1, characterized in that it is formed by a disposed filter. (3) selectively transmitting the light of the specific wavelength, and
2. The focus detection device for an endoscope according to claim 1, wherein the means for selectively receiving light of a specific wavelength is formed by a filter placed in front of the photocathode.