JPH0328686B2 - - Google Patents

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, organs within the body cavity are directly observed and diagnosed by bringing the eye close to the eyepiece of the endoscope, and 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.

Generally, the observation optical system of an endoscope is darker than the observation or photographing optical systems of other optical devices.
Furthermore, when a photograph must be taken at a close distance, there is a problem that if the subject is not in focus, the depth of focus is shallow and the photograph is likely to be out of focus. For this reason, there were cases in which it was not possible to image a constantly changing lesion, etc. without failure, and there was a problem that it could not 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 by the subject and returned for focus detection (or distance measurement). When focus detection is performed by receiving light from a camera (for use in a camera), widely diffused illumination light for observation or collation is received along with the light for focus detection, making it difficult to accurately detect focus. Ta.

The present invention has been made in view of these circumstances, and the present invention illuminates the object in a state where the object illuminated with illumination light by the illumination optical system can be observed without any trouble by the observation optical system at the time of focus detection. It is an object of the present invention to provide a focus detection device for an endoscope that can perform focus detection with high precision by preventing illumination light from having an adverse effect on focus detection.

To achieve the above object, the present invention provides an illumination optical system that guides object illumination light to the tip of an endoscope insertion section and illuminates the object, and an illumination optical system that obtains an image of the object at the light end of the insertion section and guides the object image to the eyepiece. an observation optical system; a spot light irradiation means for irradiating a focus detection spot light of a specific wavelength onto a subject via the observation optical system; a light receiving means for focus detection that receives only reflected light; and a light receiving means for detecting focus, which is provided in the irradiation optical path of the object illumination light;
and filter means for cutting off at least light of the specific wavelength from the illumination light.

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

1 and 2 relate to a first embodiment of the present invention, FIG. 1 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 elongated insertion section 2 with an illumination optical system and an objective optical system for observation disposed at its tip, and a large diameter rear end of the insertion section 2. It is composed of an operating section (grip section) 4 having a light guide base 3 formed on its side, and an eyepiece section 6 housing an eyepiece 5 behind the operating section 4. The light guide base part 3
A light guide cable 7 is connected to the light guide cable 7 so that illumination light is supplied from an external light source device 8.

The insertion section 2 is inserted into an abdominal wall 9 or the like, and an optical image formed by an internal objective optical system is transmitted to a relay optical system at a distance suitable for observing an object (subject) 10 such as an internal organ. Observation or photography can be performed from behind the eyepiece section 6 via an image transmission means such as the following. The eyepiece section 6 includes (for photographing)
The front end side of the adapter 11 is detachably attached,
A removable 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 14 that can be manually moved back and forth on the optical axis 13 as shown by a dashed line. And this photographic lens 14
On the optical axis 13 further back, there is a semi-transparent mirror (half mirror) that is inclined (for example, 45 degrees inclined) to the optical axis 13.
A focusing mirror 15 formed of .

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

The light receiving element 18 constituting the light receiving means is a second
As shown in the figure, it has a disk shape (of course, it may be square or rectangular) with an opening such as a pinhole 21 (or slit-shaped square hole) in the center, and the entire surface of this disk is illuminated. For example, elements such as photodiodes and phototransistors whose current characteristics change depending on the light incident on the PN junction surface, elements that generate photovoltaic force such as solar cells, and elements whose resistance value changes such as CDS. A photocathode 22 is formed with an element or the like, and a light shielding surface 2 is provided on the back side
3 is formed so that the light receiving element 18 is not directly exposed to light from the light source 19 for detecting focus at a position behind (above in FIG. 1) the pinhole 21.

On the other hand, the camera 12 attached from the rear of the adapter 11 has an optical axis 13 on the rear side of the focusing mirror 15 that is inclined with respect to the optical axis 13 (for example, at an angle of 45 degrees).
A return mirror 24 is provided, and a photographic film 25 is further provided behind the return mirror 24.

A pentaprism 26 is disposed on the reflected optical axis (in the upper part in the figure) of the return mirror 24, and the pentaprism 26 is horizontally inverted and returned to an erect image, and a finder lens 27 is disposed on the optical axis that reflects this pentaprism 26. , so that an optical image equivalent to that formed on the surface of the film 25 can be observed by bringing the eye close to the rear thereof. The return mirror 24 is
When taking pictures, the light that enters the film is removed from the film 2.
It is configured so that images are formed on five surfaces.

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 the optical path length when the light is reflected by the focusing mirror 15, passes through the re-imaging lens 16, and forms an image on 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, a power cord 32 provided with a power plug 31
The power supplied to the light source device 8 via the light source device 8 is transformed by a transformer 33 housed in the light source device 8, and is configured to provide alternating current power of a predetermined voltage to the control circuit 34. The power cord 32 is connected to the power switch 3 via a cord 35 inside the light source device 8.
It is configured such that the power supplied can be controlled on and off by the operation in step 6.

Lamp stand 37' disposed within the light source device 8
The light from the illumination light source (lamp) 37 attached to the
On the outer periphery of the light source device 8 at a position facing the light source 37,
A connector 40 (of the light guide cable 7) that is inserted and attached to the provided connector receiver 39
The light is projected onto the (incident) end surface 40A of the endoscope, is transmitted to the light guide base portion 3 of the endoscope via the light guide cable 7, and is further transmitted to the insertion portion 2 via the illumination light transmitting means in the endoscope 1. The light is configured to be projected toward the subject 10 in front.

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 irradiation light (inspection light) of the light source 37. There is.

That is, the knob 4 formed on the outer periphery of the light source device 8
A knob 44 is attached to the outer end of a shaft 43 that is rotatably fitted into the shaft 2 . 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 shielding plate 45 located between the light source 37 and the end surface 40A of the connector 40 is rotated. The filter 41 fixed to the formed opening 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 and is directly connected to the connector 40.
The beam is configured to be irradiated onto the end face 40A of the.

It is to be noted 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 it 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. Depending on whether or not the polarity is reversed, it is possible to detect whether or not the object is in focus. In this case, an LED or lamp may be lit in the buzzer or finder.

In the first embodiment configured in this way,
A light source 19 used for focus detection is a filter 17
The illumination light for observation or diagnosis is projected onto the subject 10 through a specific wavelength, for example, a hue that does not exist in the human body, such as a wavelength such as green, while a filter 41 prevents only the specific wavelength from passing through. This structure is a feature of the first embodiment.

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. Observe.

An adapter 11 and a camera 12 are attached to the endoscope 1, and the illuminated subject 10 is observed. In this case, the subject 10 is illuminated by the illumination light from the light source 37 with the filter 41 cutting off only light of a specific wavelength used for focus detection, and by the light source 19 for focus detection. Since it is also illuminated by the light of the cut wavelength mentioned above,
The observer is in a state where the subject 10 can be sufficiently observed. In this case, the light of the specific wavelength from the focus detection light source 19 passes through the photographic lens 14 to the subject 10.
Since the light of the specific wavelength reflected by the subject 10 is received by the light receiving element 18, the lens 14 is moved and when the focused state is reached, the light receiving element 18 Since the output level becomes the dark current level, it is possible to detect that the camera is in focus.

Note that the light receiving element 18
The behavior detected from the output is as follows.

As shown in FIG. 1, for example, when the subject 10 is at the position indicated by the symbol b, the lens 14
Assuming that the image is clearly focused on 5 planes,
In this case, the position where the light emitted from the light source 19 in a spot and reflected by the subject 10 at the position b is imaged on the optical axis reflected by the focusing mirror 15 is located at the pinhole 21. Since the light does not reach the photocathode 22, its output is at a level corresponding to dark current.

On the other hand, when the lens 14 is in focus at the point b, the image formation position of the object 10 (indicated by a in the figure) that is behind (near distance) is behind the position of the pin hold 21. Therefore, the light is received by the photocathode 22, and the output level corresponds to the amount of the received light. Similarly, when the lens 14 is in focus at point b, the object 10 is in front of it (at a far distance) (in the illustration, point c)
, the image formation position is in front of the position of the pinhole 21 and expands backward from that position, so that the light is received by the photocathode 22 . In other words, when in focus, the level corresponds to the dark current, which is the minimum value or minimum value, and when out of focus, both values are greater than that value. This means that it is possible to detect whether or not it is true.

In the focus detection described above, the light from the light source 19 used for focus detection is reduced to only a specific wavelength by the filter 17, and this light is projected onto the subject 10. On the other hand, the light of this wavelength is Since the light emitted from the illumination light source 37 toward the subject 10 is filtered by the filter 41, the focus detection is not affected by external light that is shifted from the paraxial ray and becomes a noise component. Highly accurate focus detection becomes possible. Furthermore, since only light of a specific wavelength is cut out from the illumination light, 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 reach an appropriate amount of 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, in addition to the illumination light source 37, filter 41, and shaft receiver 39 in the first embodiment, there is also a focus detection light source (lamp) 51 attached to the lamp stand 51', and the light source. Connector receivers 53 arranged in front of the connectors 51 are arranged in parallel so as to be adjacent to each other. 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 base portion 56 protruding from the adapter 11, and the light guide cable 55 is attached to the light guide base portion 56 protruding from the adapter 11. is transmitted and supplied to the adapter 11 side, and is configured to be emitted from the inner end surface of the light guide base portion 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 colors to each other; for example, when the filter 17 passes only green, the other filter 41 exhibits transmission characteristics that transmit wavelengths other than that (green). It is something. 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.

The effects of this embodiment are the same as those of the first embodiment.
Since the filter 17 prevents widely diffused illumination light used for illumination from entering the focus detection side, highly accurate focus detection is possible. Further, since sufficient illumination light is projected onto the subject 10 side, sufficient observation can be made. Furthermore, in this embodiment, since the focus detection light source 51 is housed in the light source device 8, a sufficient amount of focusing light can be projected in a spot-like manner without making the adapter 11 bulky. , the detected signal output is large and more accurate focus detection can be performed.

Figure 4 shows the light source 5 for focus detection in Figure 3.
1 is also used as an illumination light source 37.

That is, the illumination light source 37 and the filter 4 in front of it
1, a half mirror 57 is disposed at an angle between the half mirror 57 and the illumination light reflected by the half mirror 57. A condensing lens 58 and a reflecting mirror 59
are sequentially arranged, and the light reflected by the reflecting mirror 59 is transmitted to a light guide cable 55 for transmitting focused light.
It is configured so that the end face 54A of the connector 54 is irradiated with the light. The other parts are the same as those in the second embodiment.

According to this embodiment, among the illumination light for observation, the light that passes through the half mirror 57 is filtered by the filter 41 so that light other than the specific wavelength used for focus detection is transmitted, and the light guide cable 7 is The illumination light is then transmitted to the light guide base portion 3, and then is projected onto the subject 10 through the illumination light transmission means within the endoscope 1. On the other hand, a portion of the illumination light is reflected by a half mirror 57, condensed by a lens 58, and further reflected by a reflection mirror 59 to form an end surface 54 of the connector 54.
A, the light is transmitted to the adapter 11 side via the light guide cable 55, passes through the pinhole 21 of the light receiving element 18, is transmitted by the filter 17, and is further transmitted to the focusing mirror 1.
5, and is projected onto the subject 10 in a spot through a lens 14 and the like. This spot-wise projected light is photometered by the light receiving element 18 to detect whether or not it is in focus.

Therefore, the operation and effect are substantially the same as those of the second embodiment, except that only one light source 37 is required compared to the second embodiment.

FIG. 5 shows a fourth embodiment in which the collimation light and the distance measuring 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 substantially the same effects as the third embodiment, but since the illumination light and distance measuring light are effectively separated by the spectroscopic mirror 61, the light split by the half mirror 57 is further divided into Each filter 17,
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 41,
This is advantageous for observation and focus detection.

FIG. 6 shows a fifth embodiment in which a filter is provided in the light guide mouthpiece.

In this embodiment, unlike the first embodiment shown in FIG. 1, the filter 41 is not disposed within the light source device 8, but is attached to the light guide base portion 3 of the endoscope 1. A filter 72 is installed in a portion (of the light guide cable 7) close to the light guide base portion 71.
is installed.

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 guide base 3. The filter holding member 7 is fixed by a filter holding member 73 that is screwed to the light guide cap part 3.
3, a light guide base portion 71 is further configured to be attached by screwing or the like.

On the other hand, the filter 1 disposed within the adapter 11
7, as mentioned above, allows only specific wavelengths to pass through.

This embodiment has almost the same effect as the first embodiment, but according to this embodiment, if the filter 72 and the filter holding member 73 are used without modifying the light source device 8, it can be compared to the first embodiment. It has the advantage that it can be configured to perform similar functions.

This embodiment can be configured such that it is provided in the middle of the light guide cable 7, or it can be configured to use a plurality of light guide cables 7, etc., and to interpose the filter 72 on a member to which the plurality of light guide cables are connected. You can also.

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 spot-wise 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 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 for focusing.

Furthermore, if a light receiving means that is selectively sensitive to only a specific wavelength used for focus detection is used, the filter 17 can be placed behind the light receiving element 18 and in front of the light source 19 or 51, 37. can.

Note that the filter 41 disposed within the light source device 8 is
It is also possible to configure the camera to be retracted when photographing, 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, at the time of focus detection, the illumination light illuminates the object in a state where the object illuminated with the illumination light by the illumination optical system can be observed without any trouble by the observation optical system. This has the effect of allowing highly accurate focus detection without adversely affecting focus detection.

[Brief explanation of the drawing]

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. 2 shows the shape of a light receiving element in the first embodiment. 3 is an explanatory diagram showing the general configuration of the second embodiment, FIG. 4 is an explanatory diagram showing the general configuration of the third embodiment, and FIG. 5 is an explanatory diagram showing the general configuration of the fourth embodiment. 6 and 7 are related to the fifth embodiment, and FIG. 6 is an explanatory diagram showing the configuration of the fifth embodiment,
FIG. 7 is an enlarged sectional view showing the main parts around the light guide mouthpiece in the fifth embodiment. DESCRIPTION OF SYMBOLS 1... Endoscope, 6... Eyepiece, 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, 25... Film, 37...
Light source, 41... Filter, 51... Light source, 53... Connector receiver, 55... Light guide cable, 56...
Light guide base part, 57...Half mirror, 58
... Lens, 59 ... Reflection mirror, 61 ... Spectroscopic mirror, 71 ... Light guide base part, 72 ... Filter, 73 ... Filter holding member.

Claims (1)

[Scope of Claims] 1. An illumination optical system that guides object illumination light to the tip of the endoscope insertion section and illuminates the object, and an observation optical system that obtains an image of the object at the light end of the insertion section and guides the object image to the eyepiece. and a spot light irradiation means for irradiating a focus detection spot light of a specific wavelength onto the subject through the observation optical system, and of the light reflected from the subject from the observation optical system, only the reflected light of the specific wavelength is used. and a filter means provided in the irradiation optical path of the object illumination light to cut out at least light of the specific wavelength from the irradiation light of the illumination light. A focus detection device for endoscopes.