JP3477314B2 - Endoscope lighting system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination system for endoscopes used in the medical field, industrial field and the like.

[0002]

2. Description of the Related Art Endoscopes have been widely used in the medical field, industrial field and the like. In general, an endoscope is provided with an illumination system for guiding illumination light to an observation site in order to observe a narrow site such as a body cavity or a lumen that is not exposed to light.

In recent years, an electronic image pickup device has been provided at the tip of the insertion portion to pick up an image of the subject and replace it with an image guide fiber inside the insertion portion to transmit the subject image to the eyepiece on the hand side. Videoscopes have been used more frequently to obtain image signals. An endoscopic device using a videoscope can display an image of a region to be inspected on a monitor and observe and diagnose in large numbers. Further, the observation with the videoscope has advantages that the visibility is good and the observer is less tired.

The field of view of a fiberscope is usually circular, but since a videoscope often uses a solid-state image pickup device such as a CCD having a square image pickup area in an image pickup device, the observation image is displayed similarly to the fiberscope. If the shape is circular, only the circular area inscribed in the rectangular imaging area of the solid-state imaging element can be used, and the number of unused pixels is increased. Therefore, when trying to effectively use the imaging area of the solid-state image sensor,
The display shape of the observed image on the monitor in the videoscope is not a circle but a rectangle.

FIG. 22 schematically shows the characteristics of the objective optical system of the endoscope. The objective optical system 51 provided in the endoscope has a large angle of view (for example, an angle of view of 120 °, 140 °, etc.) for observing a wide range, and in such a wide-angle optical system, a large barrel distortion is provided. (Distortion aberration) occurs. Therefore, in the objective optical system of the endoscope, when viewed with reference to the image pickup surface 52 of the solid-state image pickup element, which is an image plane, a quadrangle (in the figure, four corners are chamfered)
The shape of the observation area on the object surface 53 corresponding to the image pickup area 55 becomes a large pincushion type (X shape) observation area 54 as shown by the broken line due to the distortion of the objective optical system 51.

FIG. 23 shows the relationship between the observation area and the illumination area in the endoscope provided with the above-mentioned objective optical system. The observation area by the objective optical system 62 provided at the tip of the endoscope insertion portion 61 becomes the pincushion-type observation area 54 on the object surface 53 with respect to the rectangular image pickup area of the solid-state image pickup element as described above. There is. On the other hand, the illumination optical system 63 of the endoscope
Is normally configured to illuminate a circular area, and the shape of the illumination light is a circular illumination range 5 on the object plane 53.
It is 7.

In this case, the illumination range 57 is the observation range 54
Is set to illuminate a region larger than the outer shape of the observation range 54, so that the light amount in the shaded portion in FIG. 23 is wasted.

FIG. 24 shows a configuration example of a conventional illumination system. The first lens 59 is provided in front of the light guide fiber 58.
An illumination optical system 59 composed of three lenses a, a second lens 59b, and a third lens 59c having a positive refractive power is provided, and the illumination light transmitted by the light guide fiber 58 is the third lens. The light is emitted to a subject in front of the front end surface of 59c. In this configuration, since the entrance surface of the first lens 59a and the exit surface of the third lens 59c are flat surfaces, the light rays in the peripheral portion are largely bent outward as shown in the figure, which contributes to a large light distribution angle characteristic. There is a tendency.

Recently, the size and the pixel pitch of the solid-state image pickup device have been reduced year by year in response to the demands for downsizing of the device and high resolution, and the objective optical system corresponding to this has a small pixel size. Since the depth of field becomes insufficient due to the increase in the number of lenses, it is necessary to increase the F number of the objective lens (close the aperture stop) to secure the depth of field. For this reason,
The objective optical system becomes dark, and there is a problem that the total brightness of the observation system including the objective optical system and the illumination system is insufficient with the conventional specifications.

In order to reduce the pain of the patient and improve the operability of the operator, there is a demand for the endoscope to have the insertion portion as thin as possible in accordance with the miniaturization of the solid-state image pickup device. In order to solve the lack of brightness, the illumination light amount can be increased by increasing the number of light guide fibers by increasing the size of the illumination optical system, but there is a problem that the endoscope insertion portion becomes thick.

Therefore, in order to ensure sufficient brightness of the observation system without increasing the diameter of the endoscope insertion portion, the light distribution characteristics of the illumination optical system are taken into consideration and optimized according to the shape of the observation range. There is a need to.

Techniques for changing the light distribution characteristics of the illumination optical system include Japanese Patent Publication No. 6-44107 and Japanese Patent Publication No. 7-1044.
No. 92, Japanese Patent Publication No. 7-104494, and the like.

In Japanese Patent Publication No. 6-44107, a so-called anamorphic lens having different refraction effects in the diagonal direction and the opposite side direction of the observation range is provided so that the shape of the illumination range is changed according to the shape of the observation range. The illumination optics used are shown. However, in this configuration, since the curvature of the lens is changed in the diagonal direction and the opposite side direction, although the light distribution is not particularly shown, it is considerably different from that in the axially symmetrical case. Further, with the configuration of the spherical optical system disclosed in this publication, it is difficult to arbitrarily change the refracting action of light rays so as to obtain desired light distribution characteristics.

In Japanese Patent Publication No. 7-104492 and Japanese Patent Publication No. 7-104494, light rays emitted from the peripheral portion of a light guide are illuminated by an aspherical lens in order to reduce a light amount loss occurring in the peripheral portion of the lens. Illumination optics are shown which are adapted to bend axially. However, in this configuration, since the lens system is axially symmetric, the illumination range is circular, and in the opposite side direction of the observation range, the amount of light emitted outside the observation range is large, and the light amount loss in the opposite side direction is large.
Further, if an attempt is made to reduce the light amount loss in the opposite side direction, then the light amount irradiated in the diagonal direction will decrease.

Further, in the structure of Japanese Patent Publication No. 7-104492, an aspherical anamorphic lens in which the refraction of the lens is different in the diagonal direction and the opposite side direction is used, but the shape is completely different in both directions. There is. For this reason, the light distribution is not particularly shown, but it is still fair to say that
Similar to Japanese Patent No. 4107, the shape of the illumination range does not necessarily match the shape of the observation range.

[0016]

As described above, when the observation range of the pincushion type such as the objective optical system of the endoscope is covered by the circular illumination range, the observation is performed so as to cover the entire observation range. Since the illumination range must be set so as to illuminate a region larger than the outer shape of the range, the amount of light is wasted. Recently, the objective optical system tends to become darker as the pixels of the solid-state image sensor become smaller, but in order to increase the amount of illumination light, the conventional configuration requires a large illumination optical system such as an increase in the number of light guide fibers. Therefore, the diameter of the endoscope insertion portion is increased. On the other hand, in a state where the number of light guide fibers is not increased in order to reduce the diameter of the endoscope insertion portion, it is difficult to sufficiently secure the total brightness of the observation system including the objective optical system and the illumination system. Become.

The present invention has been made in view of these circumstances. For example, an original objective optical system for an endoscope having an observation range other than a substantially circular shape on a subject surface, such as a videoscope, has been used. An object of the present invention is to provide an endoscope illumination system having a relatively simple configuration and excellent illumination efficiency without significantly changing the light distribution characteristics.

[0018]

An illumination system for an endoscope according to claim 1 , wherein a photoconductor that receives light emitted from a light source at an incident end and guides it to the other end, and the photoconductor. And an illumination optical system which is disposed close to a light emitting end from the photoconductor and irradiates a subject with light from the photoconductor, in the illumination system for an endoscope, the illumination optical system comprises: The optical element is composed of a central portion having a refraction action that is axially symmetric with respect to the optical axis and a peripheral portion having a refraction action that differs depending on the direction. The endoscope according to claim 4.
The illumination system receives the light emitted from the light source at the incident end.
And guides the light to the other end, and the photoconductor and the light.
Located near the end of the light emission from the conductor,
It consists of an illumination optical system that illuminates the subject with light from a conductor.
In the endoscope illumination system, the photoconductor is the photoconductor.
The emission angle characteristics of the light rays emitted from the light emission end of
Axisymmetric center around the axis and circumference that varies depending on direction
It is characterized in that it is composed of
It

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 relate to a first embodiment of the present invention, FIG. 1 is an operation explanatory view showing an outline of an illumination system of the present embodiment, and FIG. 2 is a diagram showing a configuration of the illumination system and a light beam passing through the illumination system. FIG. 3 is a cross-sectional view of the YZ plane in the axial direction, and FIG. 3 is an explanatory diagram showing the relationship between the shape of the display screen on the monitor and the shape of the observation range.

In the present embodiment, a configuration example in which a light guide fiber having a circular end face is used as a photoconductor that guides illumination light to the tip of the endoscope insertion portion will be described. In this embodiment, the optical axis of the illumination system is the Z axis, the emission direction is the positive direction, and the axis perpendicular to the Z axis is the radial direction of the illumination system, which corresponds to the observation range of the objective optical system. The configuration of the illumination system will be described with reference to the X-axis in the opposite side direction and the Y-axis in the other side direction orthogonal to the X-axis, and the orthogonal coordinate system of these three axes.

As shown in FIG. 2, the illumination system of the first embodiment is arranged in the vicinity of the front of the circular end face of the light guide fiber 1 and at a part of the peripheral portion of the plane of the first lens (plano-convex rod lens). Is aspherical) 2a, second lens (convex lens) 2
b, an illumination optical system 2 composed of three lenses having a positive refractive power of the third lens (plano-convex lens) 2c.

The light guide fiber 1 and the illumination optical system 2 are arranged so as to be adhered or in close contact with each other, or arranged at an appropriate interval.

The first lens 2a is constructed so that the peripheral portion of the incident end face has a larger positive refractive power than the central portion in the opposite side direction (X-axis direction and Y-axis direction) of the observation range. There is. Specifically, the incident end surface of the first lens 2a is formed with a flat surface such that the central portion has an axially symmetric refraction action with the optical axis as the center, and the peripheral portion is larger with respect to the opposite side direction of the observation range. An aspherical surface portion 3 having a positive refractive power is formed.

The aspherical portion 3 largely bends the peripheral rays of the illumination light as shown in FIG.
The illumination light emitted from c has a small emission angle, and the peripheral light rays are directed toward the central portion side in the opposite side direction.

Since the objective optical system provided in the endoscope has a large angle of view so that a wide range can be observed, barrel distortion occurs. Therefore, the shape of the observation range on the subject surface corresponding to the shape of the display screen (imaging region of the solid-state image sensor) on the monitor is, for example, as shown in FIG. It becomes a pincushion type as it is distorted so as to narrow toward the center side in the opposite direction. That is, FIG.
The observation area is distorted into a pincushion type as shown on the right side of the display screens shown on the left side of (a) to (f).

In order to improve the total brightness of the observation system, it is necessary to efficiently illuminate in accordance with the actual observation range on the subject surface. That is, an illumination optical system having a function of distributing the amount of light illuminated outside the observation range within the observation range is required. Therefore, in the illumination optical system of the present embodiment, an aspherical surface portion having a positive refractive power in the peripheral portion with respect to the opposite side direction of the observation range is provided in the lens corresponding to the above-mentioned wound type observation range. By providing it on at least one surface, a substantially pincushion type illumination range that covers the observation range is formed. This configuration is particularly effective in a videoscope using a solid-state imaging device in which the shape of the observation area is not a circle but a substantially square shape such as a square, a rectangle, or an octagon having four corners of a square chamfered.

FIG. 1 shows the relationship between the observation range and the illumination range. The illumination range 7 of the illumination light emitted from the illumination window 5 at the tip of the endoscope insertion portion 4 on the subject surface 6 is a substantially pincushion type in which the peripheral portion moves toward the center side in the opposite side direction and becomes narrower. Become. The illumination range 7 has a shape corresponding to the pincushion type observation range 9 on the object plane 6 of the objective optical system arranged in the observation window 8, covers the observation range 9 and eliminates unnecessary areas. Since it does not irradiate, there is no waste in the amount of light, and it is optimized according to the shape of the observation range. Therefore, even if the illumination light amount is the same as that of the conventional illumination optical system, the illumination efficiency in the observation range 9 is improved, and the total brightness of the observation system is improved. On the other hand, when the total brightness of the observation system is made equal, the number of light guide fibers can be reduced even with the same amount of illumination light, and thus the diameter of the endoscope insertion portion can be reduced accordingly.

In the configuration of the illumination optical system of the present embodiment, the central portion has an axisymmetric characteristic, and since the refractive power is changed only in the peripheral portion in the opposite side direction, the central portion has a light distribution characteristic by the aspherical surface portion. Does not change and does not significantly affect the overall light distribution.

As described above, in the present embodiment, at least one surface of the lens of the illumination optical system is provided with the aspherical surface portion having a positive refractive power in the peripheral portion with respect to the opposite side direction of the observation range. Since the light in the peripheral area in the opposite direction can be distributed within the observation range, it is possible to efficiently illuminate according to the actual observation range (display screen range) without significantly changing the overall light distribution characteristics. The overall brightness of the observation system can be improved while reducing the diameter of the endoscope insertion portion.

FIGS. 4 and 5 relate to a second embodiment of the present invention, FIG. 4 is a sectional view of a YZ plane in the optical axis direction showing the configuration of the illumination system, and FIG. 5 is the first lens in the illumination optical system. It is a perspective view which shows the shape of.

The second embodiment is a structural example in which an inclined plane portion formed by planar chamfering is provided in the entrance end surface of the illumination optical system instead of the aspherical surface portion of the first embodiment. . Here, only the parts different from the first embodiment will be described.

In the illumination system of the second embodiment, as shown in FIG. 4, the first lens 12a, the second lens 12b, and the third lens 12c are positively arranged close to the front of the circular end surface of the light guide fiber 1. An illumination optical system 12 including three lenses having a refracting power is disposed. As shown in FIGS. 4 and 5, the incident end surface of the first lens 12a has a flat central portion in the opposite side direction (X-axis direction and Y-axis direction) of the observation range and a central portion in the opposite side direction. A plane portion 13 is formed that is cut obliquely in a plane so as to have a positive refractive power larger than that of the portion.

By providing the inclined flat surface portion 13 in the peripheral portion in the opposite side direction on the incident end surface of the illumination optical system as described above, the same effect as that of the first embodiment can be obtained.

FIGS. 6 to 8 relate to a third embodiment of the present invention, FIG. 6 is a cross-sectional view of the YZ plane in the optical axis direction showing the configuration of the illumination system, and FIG. 7 is the third lens in the illumination optical system. 8 is a perspective view showing the shape of FIG. 8 and FIG. 8 is a cross-sectional view of a YZ plane showing an optical ray passing through the illumination system.

The third embodiment is an example in which an aspherical surface similar to that of the first embodiment is provided on the exit end face side of the illumination optical system instead of the entrance end face side. Here, only the parts different from the first embodiment will be described.

In the illumination system of the third embodiment, as shown in FIG. 6, the first lens 14a, the second lens 14b, and the third lens 14c are positively arranged close to the front of the circular end surface of the light guide fiber 1. An illumination optical system 14 composed of three lenses having a refracting power of is arranged and configured. As shown in FIGS. 6 and 7, the third lens 14c has a flat center in the opposite side direction (X-axis direction and Y-axis direction) of the observation range and a peripheral side portion in the opposite side direction on the emission end face. The aspherical surface portion 15 is formed so as to have a positive refractive power larger than that of the central portion.

As shown in FIG. 8, the aspherical portion 15 prevents the light rays of the illumination light emitted from the peripheral portion in the opposite side direction from being largely bent, so that the illumination light in the peripheral portion is not totally reflected and the light amount loss is reduced. To do.

As described above, by providing the aspherical surface portion 15 in the peripheral portion in the opposite side direction on the emission end surface of the illumination optical system,
The same effect as that of the first embodiment can be obtained. further,
In the configuration of the present embodiment, the emission angle of the illumination light is also small, and the illumination light is more concentrated in the observation range, so that the illumination efficiency and brightness can be further improved.

9 and 10 relate to the fourth embodiment of the present invention. FIG. 9 is a cross-sectional view of the YZ plane in the optical axis direction showing the configuration of the illumination system, and FIG. 10 is the third lens in the illumination optical system. It is a perspective view which shows the shape of.

The fourth embodiment is an example in which a flat portion similar to that of the second embodiment is provided on the exit end face side as in the third embodiment. Here, only parts different from those of the third embodiment will be described.

In the illumination system of the fourth embodiment, as shown in FIG. 9, the first lens 16a, the second lens 16b, and the third lens 16c are positively arranged near the front of the circular end surface of the light guide fiber 1. An illumination optical system 16 composed of three lenses having a refracting power of is arranged and configured. As shown in FIGS. 9 and 10, the emission end face of the third lens 16c has a flat center in the opposite side direction (X-axis direction and Y-axis direction) of the observation range and a center in the peripheral side in the opposite side direction. A plane portion 17 is formed that is cut obliquely in a plane so as to have a positive refractive power larger than that of the portion.

By providing the inclined flat surface portion 17 in the peripheral portion in the opposite side direction on the emission end surface of the illumination optical system as described above, the same effect as that of the third embodiment can be obtained.

11 to 13 relate to the fifth embodiment of the present invention, FIG. 11 is an explanatory view showing the shape of the display screen on the monitor, and FIG. 12 is a view showing the structure of the illumination system in the optical axis direction XZ. FIG. 13 is a perspective view showing the shape of the third lens in the illumination optical system, and FIG. 13 is a sectional view of the plane and the YZ plane.

In the above-described first to fourth embodiments,
The case where the observation range on the subject surface and the shape of the display screen on the monitor are squares having opposite sides substantially equal to each other has been exemplified, but in the fifth embodiment, the shape of the observation range is a horizontally long rectangular shape having opposite sides. This is an example of the configuration in the case of doing.

As shown in FIG. 11, when the display screen range 18 on the monitor is a horizontally long rectangular shape, the peripheral portion is formed in the vertical direction (Y-axis direction) and the horizontal direction (X-axis direction) in the opposite direction. It is necessary to change the refractive power.

In the illumination system of the fifth embodiment, as shown in FIG. 12, the first lens 19a, the second lens 19b, and the third lens 19c are arranged positively in front of the circular end face of the light guide fiber 1. An illumination optical system 19 composed of three lenses having a refracting power of is arranged and configured. On the incident end face of the first lens 19a, as shown in FIGS. 12 and 13, the central portion is flat with respect to the opposite side direction (X-axis direction and Y-axis direction) of the observation range, and the peripheral portion in the opposite side direction is Aspherical portions 20a and 20b having different refractive powers are formed so as to have a positive refractive power larger than that of the central portion.

When the observation range is horizontally long as in the present embodiment, the aspherical surface portion 20a in the horizontal direction is the aspherical surface portion 20 in the vertical direction.
By making the refractive power weaker than that of b, it is possible to efficiently illuminate according to the shape of the observation range. When the observation range is vertically long, on the contrary, the refractive power of the aspherical surface portion 20b in the vertical direction may be weakened. In this way, by changing the refractive power of the peripheral portion according to the ratio of the length and width of the shape of the observation range, it is possible to obtain the shape of the illumination range that matches the observation range.

The same configuration may be applied not only to the entrance end surface of the illumination optical system but also to other surfaces such as the exit end surface provided with an aspherical surface. Further, instead of the aspherical surface portion, the inclined flat surface portion may be provided as in the above-described embodiment.

14 and 15 relate to the sixth embodiment of the present invention, and FIG. 14 shows the configuration of the illumination system in the optical axis direction YZ.
FIG. 15 is a cross-sectional view of a plane, and FIG. 15 is an explanatory diagram showing a configuration of a conventional illumination optical system having a negative refractive power.

In the first to fifth embodiments described above,
Although the example in which the illumination optical system is configured by the lens system having a positive refractive power has been shown, in the following sixth and seventh embodiments, an example in which the illumination optical system is configured by a lens system having a negative refractive power is shown. Show.

In the illumination system of the sixth embodiment, as shown in FIG. 14, a lens having a negative refractive power (a concave surface of a plano-concave type lens) is provided close to the front of the circular end surface of the light guide fiber 1. An illumination optical system 21 having a peripheral portion (aspherical surface) 21a is arranged. An aspherical surface portion 22 is formed on the incident end surface of the lens 21a so that the peripheral portion has a negative refractive power smaller than that of the central portion in the opposite side direction (X-axis direction and Y-axis direction) of the observation range. .

In the conventional illumination optical system 60 having a negative refracting power, as shown in FIG. 15, the light rays in the peripheral portion are largely bent outward and tend to contribute to a large light distribution angle characteristic. Therefore, in the present embodiment, the light rays are not bent so much in the peripheral portion in the opposite side direction of the observation range, that is, the refractive power of the lens is reduced in the peripheral portion in the opposite side direction.
An aspherical surface portion 22 is provided around the concave surface. Instead of the aspherical surface portion, an inclined flat surface portion may be provided as in the above-described embodiment.

Even in the illumination optical system having a negative refracting power as described above, by providing the aspherical surface portion 22 in the peripheral portion of the concave surface of the incident end surface in the opposite side direction, the same effect as that of the first embodiment can be obtained. To be

FIG. 16 is a sectional view of the YZ plane in the optical axis direction showing the configuration of the illumination system according to the seventh embodiment of the present invention.

The seventh embodiment is an example in which an aspherical surface portion similar to that of the sixth embodiment is provided on the exit end face side of the illumination optical system instead of the entrance end face side. Here, only the parts different from the sixth embodiment will be described.

As shown in FIG. 16, the illumination system of the seventh embodiment is an illumination optical system which has a lens 23a having a negative refracting power in front of the circular end face of the light guide fiber 1. The system 23 is arranged and configured. The exit end surface of the lens 23a has a flat central portion in the opposite side direction (X-axis direction and Y-axis direction) of the observation range, and the peripheral portion in the opposite side direction has a negative refractive power smaller than that of the central portion. An aspherical surface portion 24 is formed on.

The aspherical surface portion 24 prevents the light rays of the illumination light emitted from the peripheral portion in the opposite side direction from being largely bent, so that the total reflection of the illumination light in the peripheral portion is reduced and the light amount loss is reduced. Instead of the aspherical surface portion, an inclined flat surface portion may be provided as in the above-described embodiment.

In this way, also in the illumination optical system having a negative refracting power, by providing the aspherical surface portion 24 in the peripheral portion of the emitting end face in the opposite side direction, the same effect as that of the first embodiment can be obtained. Further, in the configuration of the present embodiment, the emission angle of the illumination light is also small, and the illumination light is more concentrated in the observation range, so the illumination efficiency and brightness can be further improved.

In each of the above-described embodiments, a configuration example in which a light guide whose end surface is formed in a circular shape is used is shown. However, even in the case of a distorted shape such as an ellipse, the light guide of the fifth embodiment is used. As described above, if the refractive powers are changed in the longitudinal and lateral peripheral portions of the opposite side of the observation range, the same effect can be obtained. Specifically, if the end face is a horizontally long light guide, in the case of an illumination optical system having a positive refracting power, the lateral refracting power may be made larger in the peripheral portion than in the vertical direction in the opposite side direction.

In the case of an illumination optical system having a positive refracting power, the peripheral region which gives a positive refracting power larger than that of the central part is, for example, the shaded area in FIGS. 17 (a) to 17 (h). As described above, it may be applied to the observation range on the subject surface and the shape similar to the shape of the display screen on the monitor (when observed from the optical axis direction of the illumination optical system). The plane portion does not necessarily have to be a square or a rectangle. In FIG. 17, the outer shape such as a circle shows the outer shape of the light guide and the illumination optical system, and the shaded area shows the area of the aspherical surface portion or the flat surface portion provided in the peripheral portion. However, the outer shape of the illumination optical system may be larger than that of the light guide, and therefore does not necessarily match the outer shape of the light guide.

FIG. 17A shows a structure corresponding to the first to fourth embodiments, in which the shape of the central plane portion is square. (B) is an example in which an aspherical surface portion or a flat surface portion in the peripheral portion is formed small, and the shape of the flat surface portion on the center side is an octagon in which four corners of a square are chamfered.
(C) is an example in which an aspherical surface portion or a flat surface portion in the peripheral portion is formed slightly larger in the opposite side direction, and the shape of the flat surface portion on the center side is a pincushion type. (D) is an example of a D-cut type in which an aspherical surface portion or a flat surface portion is provided only in one of the opposite sides, and the shape of the central flat surface portion is a D shape. (E) is an example in which only the peripheral portion in the opposite side direction (vertical direction) of one of the vertical direction and the horizontal direction is cut, and the shape of the plane portion on the center side is substantially a pincushion type. (F) is an example in which only the peripheral portion in the opposite side direction (vertical direction) of one of the vertical direction and the horizontal direction is linearly cut to make the shape of the flat portion on the center side oval.

The end face shapes of the illumination optical system and the light guide do not necessarily have to be circular as described above, and are formed into a substantially circular shape, an oval shape, an elliptical shape, a polygonal shape such as a hexagonal shape or an octagonal shape. May be used. FIG. 17 (g) shows
This is an example of the case where the outer shapes of the illumination optical system and the light guide are elliptical, and the aspherical surface portion or the flat surface portion is provided in the peripheral portion in the opposite direction, and the shape of the flat surface portion on the center side is the same as in the fifth embodiment. Is a horizontally long rectangle. (H) is an example of the case where the outer shape of the illumination optical system and the light guide is an octagon in which the four corners of a square are chamfered, and an aspherical surface portion or a flat surface portion is provided in the peripheral portion in the opposite side direction, and a flat surface portion on the center side. Has a square shape. In this way, the refractive power of the peripheral portion in the opposite side direction is determined in consideration of both the end surface shapes of the illumination optical system and the light guide, the observation range on the subject surface, and the shape of the display screen on the monitor, and the aspherical surface is determined. It suffices to form a flat portion or a flat portion.

Further, in each of the above-mentioned embodiments, the entrance end face and the exit end face of the illumination optical system are flat, but they may have a curvature. Further, the surface shape change between the central portion and the peripheral portion may be continuous as in the case of providing the aspherical surface portion, or may be discontinuous as in the case of providing the flat surface portion. Absent.

The aspherical surface portion or the flat surface portion for changing the refracting power in the peripheral portion may be provided at a position other than the incident end face and the output end face of the illumination optical system, or the surface shape shown in the above embodiment may be used. A plurality of illumination optical systems may be combined and configured. Further, the aspherical surface portion and the flat surface portion may be mixed in different opposite side directions on the same surface.

In each of the above-mentioned embodiments, the configuration of the illumination optical system provided at the tip of the photoconductor such as the light guide fiber has been described. However, even if the same configuration is applied to the photoconductor, the same operation is performed. , The effect can be realized.

Therefore, a configuration example in which the configuration of the above embodiment is applied to a light guide fiber as a photoconductor will be shown below.

18 and 19 relate to the eighth embodiment of the present invention, and FIG. 18 shows the configuration of the illumination system in the optical axis direction YZ.
FIG. 19 is a cross-sectional view of the plane, and FIG. 19 is a perspective view showing the shape of the emitting end face of the photoconductor.

In the illumination system according to the eighth embodiment, as shown in FIG. 18, a light guide fiber 25 is provided as a photoconductor in the endoscope insertion portion.
The first lens (plano-convex rod lens) 27a, the second lens (convex lens) 27b, and the third lens (plano-convex lens) 27c having positive refracting power in close proximity to the front of the exit end surface
An illumination optical system 27 including a single lens is provided.

The exit end face of the light guide fiber 25 is
As shown in FIGS. 18 and 19, as in the second embodiment, the central portion is a plane in the opposite side direction (X axis direction and Y axis direction) of the observation range, and the peripheral portion in the opposite side direction is the central portion. A plane portion 26 is formed that is cut obliquely in a plane so as to have a larger positive refractive power. Therefore, the end faces of the fibers arranged in the peripheral portion are cut obliquely.

In this case, the cut surface, including the flat surface portion 26, is left with scratches on the cut surface to cause a loss of the emitted light amount. Therefore, if the end face is mirror-finished, the emitted light amount is reduced. So more desirable. Even in the case of the lens of the illumination optical system in each of the above-mentioned embodiments,
It may be partially or wholly roughened (grained) if there is a margin of light quantity, but it goes without saying that mirror finishing is also preferable.

When the light guide fiber 25 is constructed as described above, the peripheral flat surface portion 26, which is particularly obliquely cut, is formed.
The light beam emitted from is bent in the direction of the optical axis and is incident on the illumination optical system 27 that is adhered or closely contacted with the light guide fiber 25 or that is arranged with an appropriate space, and the flat surface portion 13 of the second embodiment is used. Since an effect similar to the effect is obtained and the light ray travels along the same path in the illumination optical system as in FIG. 2, the emission angle of the light ray from the illumination system emission end in the opposite side direction of the observation range can be reduced.

Therefore, the illumination range in the opposite direction of the observation range is narrowed and the illumination efficiency in the observation range is improved, so that the illumination in the observation range can be made bright. In the diagonal direction of the observation range, since the emission angle of the light beam does not change, the light distribution characteristic of the peripheral portion in the diagonal direction can maintain the same performance as that of the current state.

The shape of the peripheral portion of the emission end face of the light guide fiber is not limited to the oblique cut of the flat portion, and various modifications can be considered as in the case of the above-mentioned illumination optical system. For example, like the light guide fiber 28 shown in FIG. 20, an aspherical surface portion 29 similar to that of the first embodiment may be provided on the emission end surface to have a shape other than a flat surface. Further, such an aspherical surface portion may be continuous or discontinuous in shape, and may have a configuration in which a flat surface portion and an aspherical surface portion are used together.

As in the fifth embodiment, like the light guide fiber 30 shown in FIG. 21, an aspherical surface having different refractive powers in the X-axis direction and the Y-axis direction in the peripheral portion of the observation range in the opposite side direction. The portions 31a and 31b may be formed to have different peripheral shapes in the opposite side directions.

In the eighth embodiment, the light guide has a circular cross section, but it may have a polygonal shape, an elliptical shape, an oval shape, a crescent shape, a semicircular shape or the like.
When forming the end surface of the light guide fiber,
The tip of the light guide fiber may have a planar structure and then the peripheral portion may be cut and polished, or the peripheral portion of the end face may be polished after being formed into a rough shape.

Further, in the eighth embodiment, the configuration of the illumination optical system provided at the tip of the photoconductor has a three-lens configuration, but a lens system such as a negative lens may be used. It may be good, or may include an optical element other than the lens system. Further, the photoconductor is not limited to the light guide fiber, and a photoconductor including other optical elements may be used.

Furthermore, the illumination system may be configured by combining a plurality of the configuration examples of the above-described embodiments.

As described above, according to the configuration of each of the above-described embodiments, the illumination range of the endoscope illumination system is substantially similar to the observation range of the objective optical system.
Especially for an endoscope with a non-circular observation range such as a videoscope, even if the same configuration as the conventional light guide or illumination optical system is used, this is performed with the combined illumination optical system or light guide. By providing the configuration of the form, it is possible to improve the illumination efficiency and improve the total brightness of the observation system, and it is possible to provide a bright endoscopic observation image. Furthermore, if the same brightness as the conventional one is obtained, a smaller-diameter illumination with a smaller number of light guides is configured while ensuring the required brightness and peripheral light distribution according to the usage status of the endoscope. Since the system can be configured, it is possible to bring about a great effect in reducing the diameter of the endoscope.

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As described above, according to the present invention, the original light distribution is applied to an objective optical system of an endoscope having an observation range other than a substantially circular shape on a subject surface such as a videoscope. There is an effect that it is possible to provide an endoscope illumination system with excellent illumination efficiency with a relatively simple configuration without significantly changing the characteristics.

[Brief description of drawings]

FIG. 1 is an operation explanatory view showing an outline of an illumination system of the present embodiment.

FIG. 2 is a cross-sectional view of the YZ plane in the optical axis direction, showing the configuration of the illumination system according to the first embodiment of the present invention and the rays of light passing through the illumination system.

FIG. 3 is an explanatory diagram showing the relationship between the shape of the display screen on the monitor and the shape of the observation range.

FIG. 4 is a sectional view of a YZ plane in an optical axis direction, showing a configuration of an illumination system according to a second embodiment of the present invention.

5 is a perspective view showing the shape of a first lens in the illumination optical system of FIG.

FIG. 6 is a cross-sectional view taken along the YZ plane in the optical axis direction, showing the configuration of an illumination system according to a third embodiment of the present invention.

7 is a perspective view showing the shape of a third lens in the illumination optical system shown in FIG.

8 is a cross-sectional view of a YZ plane in the optical axis direction, showing a ray of light passing through the illumination optical system of FIG.

FIG. 9 is a cross-sectional view taken along the YZ plane in the optical axis direction, showing the configuration of an illumination system according to a fourth embodiment of the present invention.

10 is a perspective view showing the shape of a third lens in the illumination optical system in FIG.

FIG. 11 is an explanatory diagram showing the shape of a display screen on a monitor according to the fifth embodiment.

FIG. 12 is a cross-sectional view of an XZ plane and a YZ plane in the optical axis direction, showing the configuration of an illumination system according to a fifth embodiment of the present invention.

13 is a perspective view showing the shape of a third lens in the illumination optical system in FIG.

FIG. 14 is a sectional view of a YZ plane in the optical axis direction, showing the configuration of an illumination system according to a sixth embodiment of the present invention.

FIG. 15 is an explanatory diagram showing a configuration of a conventional illumination optical system having negative refractive power.

FIG. 16 is a cross-sectional view taken along the YZ plane in the optical axis direction, showing the configuration of an illumination system according to a seventh embodiment of the present invention.

FIG. 17 is an explanatory diagram showing a modified example of a peripheral region that gives a positive refractive power larger than that of the central part in the illumination optical system, and a modified example of the outer shape of the illumination system.

FIG. 18 is a cross-sectional view of the YZ plane in the optical axis direction showing the configuration of the illumination system according to the eighth embodiment of the present invention.

FIG. 19 is a perspective view showing the shape of the emission end face of the photoconductor of FIG.

FIG. 20 is a perspective view showing a first modification of the end face shape of the photoconductor.

FIG. 21 is a perspective view showing a second modification of the end face shape of the photoconductor.

FIG. 22 is an operation explanatory view schematically showing the characteristics of the objective optical system of the endoscope.

23 is an explanatory diagram showing a relationship between an observation region and an illumination region in an endoscope including an objective optical system having the characteristics shown in FIG.

FIG. 24 is a sectional view in the optical axis direction showing a configuration example of a conventional illumination system.

[Explanation of symbols]

1 ... Light guide 2. Illumination optical system 3 ... Aspherical surface 4 ... Endoscope insertion part 6 ... Subject surface 7 ... Illumination range 9 ... Observation range

Continuation of the front page (56) Reference JP-A-5-53063 (JP, A) JP-A-6-273678 (JP, A) JP-A-7-311349 (JP, A) JP-A-57-97509 (JP , A) Japanese Patent Publication 6-44107 (JP, B2) Japanese Patent Publication 7-104492 (JP, B2) Japanese Publication 7-104494 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) A61B 1/00-1/32 G02B 23/24-23/26

Claims (9)

(57) [Claims] 1. A photoconductor that receives light emitted from a light source at an incident end and guides the light to the other end, and the photoconductor and the photoconductor and a light emitting end from the photoconductor are arranged in proximity to each other. And an illumination optical system for irradiating a subject with light from the photoconductor, wherein the illumination optical system has a center portion and a direction having an axisymmetric refraction action about an optical axis. An illumination system for an endoscope, comprising an optical element having a peripheral portion having different refraction depending on the type. 2. Corresponding to the opposite side direction of the endoscopic observation shape,
The endoscope illumination system according to claim 1, wherein the illumination optical system has different refracting powers in at least one peripheral portion in the opposite side direction. 3. The endoscope illumination system according to claim 1 or 2, wherein a lens is used as the optical element. 4. The light emitted from the light source is received at the incident end.
A photoconductor that emits light and guides it to the other end;
The light emitted from the photoconductor is placed close to the end,
It consists of an illumination optical system that illuminates the subject with light from the conductor.
In the illumination system for an endoscope, the photoconductor is
The emission angle characteristic of the light beam emitted from the light emission end of the body is
Axisymmetric about the optical axis and varies depending on the direction
It is characterized in that it is composed of a peripheral portion
Illumination system for endoscopes. 5. Corresponding to the opposite side direction of the endoscopic observation shape,
The photoconductor is different in at least one opposite side peripheral portion.
Claims characterized in that
Item 4. The endoscope illumination system according to Item 4. 6. A fiber is used as the photoconductor.
The endoscopic view according to claim 4 or 5, wherein
Lighting system for mirrors. 7. An illumination optical system or a photoconductor of the illumination system.
Characterized in that at least one aspherical surface is provided
The illumination system for an endoscope according to claim 3 or claim 6. 8. An illumination optical system or a photoconductor of the illumination system.
At least one surface is inclined with respect to the optical axis on the periphery of
4. A flat surface portion is provided, or claim 3 or claim
Item 9. The endoscope illumination system according to Item 6. 9. The illumination optical system includes a plurality of positive lenses.
Only the lens near the light entrance end or the light exit end of the illumination optical system.
At least one aspherical surface or flat surface is provided on the inner surface.
The inside of claim 7 or claim 8 characterized in that
Illumination system for endoscopes.