JPH0743620A - Illuminating optical system for endoscope and illuminating lens - Google Patents

Abstract

PURPOSE:To provide an illuminating optical system for endoscope and an illuminating lens for the illuminating optical system for endoscope capable of brightly illuminating even the periphery of a visual field and reducing the loss of light quantity as little as possible. CONSTITUTION:An illuminating lens 10 composing an illuminating optical system for endoscope is composed so as to comprise the plural lines of ring zone-like projecting parts 12 whose cross section are V-shaped being adjacent to each other on the concentric circles around the optical axis on the surface of a lens main body 11 on the side of a light emitting body, by representing a tilt angle to the optical axis on a slope 13a on the side of the optical axis by theta1, a tilt angle to the optical axis on a slope 13b on the opposite side of the optical axis by theta2 and the refractive index of the lens main body by (n), the V-shaped cross section of the respective ring zone-like projecting parts 12 is formed so as to satisfy the condition shown by the expression.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical system for endoscopes and an illumination lens.

[0002]

2. Description of the Related Art In recent years, with the widening of the observation optical system in endoscopes, the illumination optical system has been gradually required to have a wider angle. As an illumination optical system for this type of endoscope,
The configuration shown in FIG. 16 is adopted, which is capable of illuminating a wide angle range and is relatively structurally simple. That is, the general illumination optical system for an endoscope shown in FIG. 16 has a light guide fiber bundle 31 for guiding the light flux from the light source unit, in front of the exit end face of the light guide fiber bundle 31,
That is, the illumination lens 32 having the inner concave surface 33 for light diffusion is arranged on the observed object side, and the illumination light flux emitted from the emission end surface of the light guide fiber bundle 31 is diffused in a wide range by the illumination lens 32. It was done like this. However, in the case of the general configuration shown in FIG. 16, some rays of the illumination light flux refracted by the inner concave surface 33 of the applied illumination lens 32 are diffusely reflected by the inner surface of the outer periphery of the illumination lens 32 and disappear. In the same manner, by being totally reflected by the inner surface of the outer peripheral portion and heading toward the central portion of the visual field or the light guide fiber bundle 31, the light distribution to the peripheral portion of the visual field becomes insufficient, and the light is distributed over a wide range. However, there is an inconvenience that uniform illumination cannot be performed.

Therefore, in order to eliminate such inconvenience,
In a conventional endoscope illumination optical system, as shown in FIG. 17, a Fresnel lens 34 is used in place of the illumination lens 32 having the inner concave surface 33, and light is diffused by the Fresnel lens 34. There is. That is, this FIG.
In the illumination optical system for an endoscope using the Fresnel lens 34 as the illumination lens, as shown in Fig. 16, the inner concave surface 33 in the case of the illumination lens 32 shown in Fig. 16 is concentric with the optical axis as the center. By adopting a mode in which a plurality of annular zones 35 are formed separately adjacent to each other above,
It is possible to reduce the thickness in the optical axis direction at the outer peripheral portion, and it is possible to prevent the light rays traveling toward the peripheral portion of the visual field from being eclipsed at the inner surface of the outer peripheral portion.

[0004]

However, the illumination optical system for an endoscope using the Fresnel lens 34 as described above also has the following drawbacks. That is, in the case of the Fresnel lens 34, as shown in FIG. 18, since the step surface 37 is inevitably formed between the adjacent ones of the respective annular zones 35, the light guide fiber bundle 31 is A part of the illumination light flux emitted from the emission end face and incident on the slope 36 close to the step face 37 is diffusely reflected by the inner face of the step face 37 and disappears, or is totally reflected and the direction thereof is changed. The illuminance will decrease due to reasons such as changes. On the other hand, if the Fresnel lens 34 having such a structure is applied to a relatively wide-angle illumination optical system, among the respective ring zones 35, the ring zones 35 located in the outer peripheral portion are formed. Since the inclination angle of the slope 36 becomes large, the rate at which the light rays are eclipsed by the corresponding step surface 37 also inevitably increases, and as a result, the distribution to the peripheral part of the visual field is the same as in the previous case. Insufficient light,
It becomes impossible to achieve the desired bright illumination.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to:
It is an object of the present invention to provide an illumination optical system and an illumination lens for an endoscope that can brightly illuminate a peripheral portion of a visual field and can reduce a light amount loss as much as possible.

[0006]

In order to achieve the above object, an endoscope illumination optical system and an illumination lens according to the present invention each have a V-shaped cross section on the light emitter side surface of the lens. The V-shaped slopes are provided with a plurality of annular zone-shaped convex portions formed so as to satisfy specific conditions so as to be adjacent to each other on a concentric circle about the optical axis.

That is, the present invention comprises a light emitting body as a light source,
In an illumination optical system for an endoscope, comprising: an illumination lens arranged in front of the light emitting body, wherein the illumination light flux emitted from the light emitting body is diffused by the illumination lens. The body-side surface is configured to have a plurality of cross-section V-shaped or substantially V-shaped ring-shaped protrusions adjacent to each other on a concentric circle centered on the optical axis, and each of the ring-shaped protrusions The cross-sectional V-shape or the substantially V-shape of the part has a tilt angle of the optical axis side slope with respect to the optical axis θ ₁ , an inclination angle of the non-optical axis side slope with respect to the optical axis θ ₂ , and a refractive index of the lens body. When n, The illumination optical system for an endoscope is characterized by being formed so as to satisfy the following condition.

Further, according to the present invention, a plurality of rows of V-shaped cross sections adjacent to each other on a concentric circle centered on the optical axis are provided on one surface,
Alternatively, in the illumination lens of the illumination optical system for an endoscope in which a ring-shaped convex portion having a substantially V-shape is formed, the cross-sectional V-shaped or substantially V-shaped shape of each ring-shaped convex portion is the optical axis. When the inclination angle of the side slope to the optical axis is θ ₁ , the inclination angle of the non-optical axis side slope to the optical axis is θ ₂ , and the refractive index of the lens body is n, The illumination lens is formed so as to satisfy the following condition.

Therefore, in the present invention, by using the illumination lens for the endoscope which satisfies the above conditions, the illumination optical system for the endoscope which can brightly illuminate the peripheral portion of the visual field and has a small light amount loss can be obtained.

Subsequently, the features of the present invention will be described in detail with reference to FIGS. 1 to 6 in the accompanying drawings.

Here, it is generally known that the illumination luminous flux emitted from the light source such as the light emitting element has a unique light distribution characteristic. For example, the relationship between the emission angle of the illumination light flux and the irradiation intensity, which is often used as an illumination light source for an endoscope of this type and is emitted through a light guide fiber bundle, is as shown in FIG. hand,
As is clear from FIG. 1, the emitted illumination light flux has a strong directivity in the vicinity of the emission angle of 0 °.

Usually, the light beam emitted from the light source is
The light rays are made incident on the illumination lens at different angles and are refracted at the incident surfaces, respectively, and then the light rays are emitted from the emission surface of the illumination lens depending on the sectional shape of the illumination lens. Before, it may be scattered and disappeared on the inner surface of the lens boundary, or it may be totally reflected to change its direction. For example, among light rays emitted from a light source having a light distribution characteristic with a strong directivity as shown in FIG. 1, a light ray having a relatively large emission angle and a relatively weak irradiation intensity is Even if the light beam is eclipsed, it has almost no effect on the light distribution characteristics on the surface to be irradiated, but in contrast to this, the emission angle of the light beam from the light source is relatively small and the irradiation intensity is small. In the case of a relatively strong light ray, when the light ray is eclipsed, the amount of the eclipsed light becomes remarkable, and the light distribution characteristic on the irradiated surface is greatly affected. That is, the illumination light flux emitted from the light source in this manner has a range that particularly strongly contributes to the light distribution characteristics of the illumination lens. This range is shown in FIG. In general, assuming that the light distribution follows a Gaussian distribution, approximately 75% of the light rays
Will be concentrated in the range where the intensity ratio is 0.5 or more, and this range mainly has a strong influence on the light distribution characteristics on the irradiated surface. As shown in FIG. 2, the emission angle of the light beam emitted from the light source when the intensity ratio is 0.5 is about 25 °, and the light beam with the emission angle larger than this is defined as the boundary. Does not significantly affect the light distribution characteristics on the illuminated surface.

In order to eliminate the light beam eclipse due to the presence of the stepped surface between the adjacent annular zone convex portions, which is a drawback of the conventional Fresnel lens, the individual annular zones are traversed individually. By forming the surface into a V-shape or a substantially V-shape, the existence of the problematic step surface itself may be eliminated. However, on the other hand, if an attempt is made to illuminate a wide-angle range using such an illumination lens, the cross section V
It is necessary to make the included angle formed by the V-shape or the substantially V-shape sufficiently acute, but in this case, for example, as shown in FIG. 3, on the light emitter side surface of the lens body 11 of the illumination lens 10. Light rays having an intensity ratio of 0.5 or more that are incident on the one side slope 13a of the ring-shaped convex portion 12 formed in a V-shaped or substantially V-shaped cross section are almost not generated on the other side slope 13b. Since the light is totally reflected, the illuminance in the peripheral part of the visual field is reduced. Therefore, in the illumination optical system for an endoscope of the present invention, as shown in FIG. 4, a V-shaped cross section or a substantially V-shaped cross section at the annular projection 12 (hereinafter, in order to avoid complication of description, The one side sloping surface 13a and the other side sloping surface 13b are parallel to the optical axis through the apex of the V-shape. By defining the respective angles θ ₁ and θ ₂ with respect to the straight line, among the light rays incident on the one side slope 13a, light rays in a range that particularly strongly contributes to the light distribution characteristic at least on the irradiated surface. However, the other one side slope 13b is designed not to be totally reflected.

In FIG. 4, 1 on one slope 13a
A light ray incident on the point at a certain angle is refracted on the incident surface. In this case, the light ray in the hatched region is totally reflected by the inner surface of the other sloped surface 13b, and thus is illustrated. Although it is not possible to contribute to the light distribution on the illuminated surface that is omitted, if light rays with an intensity ratio of 0.5 or more contribute to the area other than the shaded area, the slope 13a should be on the illuminated surface. It does not significantly damage the distribution characteristics.

At this time, as the angles of the slopes 13a and 13b of the ring-shaped convex portions 12, respective angles θ ₁ and θ ₂ with respect to a straight line passing through the apex of the V-shaped convex portion and parallel to the optical axis are set. The conditional expression to be defined is derived as follows. That is, FIG.
As shown in (a), here, each slope 13a,
The angles formed by 13b and the straight line parallel to the optical axis passing through the intersection (vertex of the V-shaped convex portion) Q of the slopes 13a and 13b are respectively set to θ ₁ and θ _2, and on one slope 13a 1 point P
On the other hand, it is assumed that a light ray 1 having an emission angle of 0 ° is incident from the light source. And the intersection Q of each slope 13a, 13b
A straight line parallel to the optical axis passing through is the Y axis, a straight line passing through the intersection point Q and orthogonal to the Y axis is the X axis, and the point P is the X'axis parallel to the X axis. Let α be the refraction angle of
And Now, in order that the light ray l'refracted at the point P on the one slope 13a does not hit the other slope 13b, it is necessary that at least the light ray l'and the slope 13b be parallel. At this time, the angles θ ₁ and θ ₂ and the emission angle α of the ray l ′ are
As is clear from FIG. 5 (a), the relational expression with is 90 ° -θ ₂ = θ ₁ + α (1). Further, on the point P, the relationship of sin (90 ° −θ ₁ ) = n · sin α (2) holds. However, n is the refractive index of the illumination lens 10. From the equations (1) and (2), n · cos (θ ₁ + θ ₂ ) = cos θ ₁ (3) is derived. Then, the above equation (3) can be easily solved when θ ₁ = θ ₂ , However, 0 <θ ₁ <90 °. On the other hand, the condition that the light ray 1 having an emission angle of 0 ° from the light source does not hit the slope 13b is that the angle θ ₁ formed between the slope 13a and the Y axis is Becomes At this time, the angle θ ₂ formed by the slope 13b and the Y axis may be θ ₂ ≧ θ ₁ .

Next, as shown in FIG. 5 (b), it is assumed that a light ray k having an emission angle ε from the light source is incident on a point P on the slope 13a. When the ray refracted at the point P is k ′ and the refraction angle of the ray k ′ is α ′, the ray k ′ refracted at the point P does not hit the slope 13b. The relational expression of the angles θ ₁ , θ ₂ and α ′ required for the equation is 90 ° −θ ₂ = θ ₁ + α ′ ... (6), as is clear from FIG. 5 (b). Further, on the point P, the relationship of sin (90 ° −θ ₁ + ε) = n · sin α ′ ... (7) holds, and from the above equations (6) and (7), n · cos (θ ₁ + Θ ₂ ) = cos (θ ₁ −ε) (8) is derived. Then, in the above formula (8), when θ ₁ = θ ₂ , n · cos ₂ θ ₁ = cos (θ ₁ −ε) ... (8 ′), and appropriate values are applied to the angle ε and the refractive index n. As a result, the angle θ ₁ formed by the slope 13a and the Y axis is determined.

Further, the relationship between the refractive index n and the angle θ ₁ when the values of the angle ε and the refractive index n are appropriately changed is shown in the graph of FIG. When a light ray emitted from the light source within an angle of 25 ° strongly contributes to the light distribution characteristic on the illuminated surface of the illumination optical system, the angle ε =
Where defined by the graph of Figure 6 showing the relationship between the refractive index n and the angle theta ₁ when formed into a 25 °, the angle theta ₁ between the inclined surface 13a and the Y-axis, the present invention herein This is the lower limit of the condition of the angle θ _{1 to be} satisfied, and in the case of FIG. 6, the value of the angle θ ₁ when the angle ε = 25 ° is about the value of the angle θ ₁ when the angle ε = 0 °. It turns out that it becomes sharp by about 3 °.

That is, as a result of the trial conducted by the inventors of the present invention in consideration of the light distribution distribution characteristic of the light source that can be used in the illumination optical system of the endoscope, the condition of the angle θ ₁ is as follows. It becomes like a formula. Therefore, the lens body 1 in the illumination lens 10 according to the present invention
The conditions to be satisfied by the ring-shaped protrusion 12 having a V-shaped cross section formed on one surface are as follows: Becomes

Here, in the equation (10), when the angle θ ₁ takes a value smaller than the lower limit value, 1 of the slope 13a is used.
Of the rays incident on the point P, all the rays that strongly contribute to the light distribution characteristic on the illuminated surface of the illumination optical system are in a state of being eclipsed, and the slope 13a should be on the illuminated surface. It is not preferable because it will significantly impair the light characteristics. On the other hand, since the illumination lens 10 according to the present invention is formed by forming the ring-shaped convex portion 12 having the slopes 13a and 13b having a V-shaped cross section on the surface of the lens body 11, the respective V-shaped slopes are formed. Angles θ ₁ and θ ₂ at 13a and 13b
Does not exceed 90 °.

According to the equation (10), the lower limits of the angles θ ₁ and θ ₂ formed by the slopes 13a and 13b having the V-shaped cross section are also determined by the refractive index n of the glass material used for the lens body 11. Therefore, the lower limit value can be changed by selecting the material of the glass material to be applied. For example, the light distribution angle is 1
When trying to obtain a wide-angle illumination lens of 20 ° or more,
It is necessary to make the angles θ ₁ and θ ₂ formed by the slopes 13a and 13b more acute, but since the illumination lens in this type of endoscope is generally relatively small, the cross section here is relatively small. If the V-shape is made too sharp, the machining accuracy cannot be maintained and the tip portion may be crushed or chipped. Therefore, in such a case,
A glass material having a high refractive index n may be selected so as to alleviate the sharpening of the corresponding angles θ ₁ and θ ₂ .

Further, in the illumination lens 10 according to the present invention, each of the slopes 13a having a V-shaped cross section is formed on the surface of the lens body 11,
Since it is configured by forming the ring-shaped convex portion 12 having 13b, the contribution of the light distribution from each of the slopes 13a and 13b on the illuminated surface that is extremely close to the illumination lens 10 is
It appears as mottled unevenness, but when considering the depth of field of the objective lens in this type of endoscope, in the case of a close proximity state, it is outside the depth of field of the objective lens, There is no fear of affecting at all. The illumination lens 10 of the present invention can be easily manufactured by, for example, press molding, so that the manufacturing cost can be sufficiently reduced.

[0022]

EXAMPLES Next, different examples of the illumination optical system for endoscopes and the illumination lens according to the present invention will be described with reference to FIGS.
It will be described with reference to FIG.

First embodiment . 7 and 8 show the first embodiment of the present invention.
An example is shown. In the configuration of FIGS. 7 and 8, in the first embodiment, with respect to the illumination lens 10 arranged in front of the emission end face of the light guide fiber bundle 20,
With respect to the plurality of ring-shaped convex portions 12 formed adjacent to each other on the surface of the lens body 11 concentrically around the optical axis, the angle θ ₁ of the V-shaped slope 13a on the optical axis side and the non-optical axis The angle θ ₂ of the V-shaped slope 13b on the side is θ ₁ = θ
_It is formed by a V-shaped cross section so as to have a size of 2, and can illuminate a range of an observation viewing angle of about 80 °. In this case, the refractive index n of the lens body 11
= 1.883, the angles θ ₁ = θ ₂ = 35 ° of the respective V-shaped slopes 13a and 13b are set. Further, in the first embodiment, in order to prevent a decrease in illuminance at the peripheral portion of the visual field due to the light rays on the inner surface at the outer peripheral portion 11a of the lens body 11, as shown in FIG. Direction, in this case the outer circumference 1 here
In order to effectively prevent the light rays from being eclipsed on the inner surface of 1a, the outer peripheral portion 11a in the radial direction is formed for the reason described above.
Where a is an extension distance of a, an extension thickness is b, and an angle between a slope most distant from the optical axis and a straight line parallel to the optical axis is θ ₀ , a = b · tan θ ₀ is set. Is desirable.

Here, in the illumination lens 10 for illuminating a comparatively narrow range with an observation viewing angle of about 80 ° or less as in the configuration of the first embodiment, the cross section V of each annular zone convex portion 12 is taken.
With respect to the slopes 13a and 13b having the character shape, the respective angles θ ₁ and θ ₂ with respect to the straight line parallel to the optical axis are set to θ ₁ = θ _2, and all of them have the same cross-sectional shape as shown in FIG. It may be formed. The light distribution intensity distribution on the illuminated surface in this case depends on the set dimension of each part in each ring-shaped convex portion 12, but in the sectional configuration of FIG. The contribution of the slope facing the left side and the contribution of the slope facing the right side are overlapped with each other, and at a position sufficiently distant from the illumination lens 10, a light distribution intensity distribution as shown in FIG. 9 is displayed. Good and sufficient illumination can be achieved in the range of the observation viewing angle of 80 ° or less. On the other hand, when the V-shaped cross-sections of all the ring-shaped protrusions 12 are formed to be equal in this way, the workability of the lens itself can be improved.

Further, in the case of the first embodiment, all the V-shaped convex portions 12 are formed to have the same V-shaped cross section, but a relatively wide range with an observation viewing angle of 80 ° or more. In order to make the illumination lens 10 capable of illuminating satisfactorily, it is desirable that all of the ring-shaped projections 12 have different V-shaped cross sections. That is, the viewing angle of view 80
As the illumination lens 10 for illuminating a range of 0 ° or more, when all the ring-shaped projections 12 are formed to have the same V-shaped cross section as in the first embodiment, the respective slopes are irradiated. The contribution of the light distribution on the surface is a light distribution intensity distribution having two peaks at a position sufficiently distant from the illumination lens 10 as shown in FIG. 10. In actual observation, this is what is called illuminance unevenness. It is not preferable because it appears.

Therefore, as a modified example of the first embodiment, all of the ring-shaped convex portions are formed so that all the V-shaped cross sections thereof are different from each other, so that the respective rings are formed. As shown in FIG. 11, the contributions of the light distributions made by the respective slopes of the band-shaped convex portion on the illuminated surface are mixed sufficiently with each other and have a common peak in the central portion at a sufficient distance from the illumination lens. The desired light distribution intensity distribution is obtained.

[0027]Second embodiment． Next, FIG. 12 and FIG.
2nd Example of invention is shown. The second embodiment is based on the conventional example.
For the concave lens as shown in FIG.
The present invention is applied. That is, as shown in FIG.
The optical axis is the z-axis with respect to the concave surface of the lens, and
After taking the x-axis perpendicular to the optical axis in the radial direction, the concave surface is the z-axis
Divided into n (n is an even number) areas with an appropriate width Δh in the direction
In addition, the lens surface in each area
The approximate light distribution that contributes is calculated, and this is calculated in this example.
Each slope of the illumination lens due to the V-shaped cross section
Applied to the slope of. And in the case of the second embodiment,
Is divided into 6 areas and the lighting shown in cross section in FIG.
The lens was formed. Here, the refractive index of the illumination lens is n
= 1.883, and each axis y parallel to the optical axis ₁₀₁, y₁₀₂, y
₁₀₃With respect to the angle θ formed by each slope_101aWhen
θ_101b, Θ_102aAnd θ_102b, Θ_103aAnd θ_103bIs as shown in the following table
Is.

Therefore, as in the second embodiment, if each slope having a V-shaped cross section is formed to have an acute angle shape as it goes away from the optical axis of the illuminating lens, as shown in FIG. In the same manner as shown in FIG. 3, an illumination optical system having an illuminance peak at the center of the field of view and less illuminance drop even at the periphery of the field of view can be realized. With the illumination optical system of the second embodiment, it is possible to satisfactorily illuminate a relatively wide range with an observation viewing angle of 80 ° or more.

Third Embodiment . 14 and 15 show a third embodiment of the present invention. The third embodiment applies the present invention to an illumination lens having an aspherical surface as shown in FIG. That is, also in this case, as shown in FIG. 14, with respect to the aspherical surface of the lens, the optical axis is taken as the z axis, and the x axis is taken in the radial direction perpendicular to the optical axis, As in the case of the second embodiment, the aspherical surface is divided into n (n is an even number) areas with an appropriate width Δh in the z-axis direction. However, as in the third embodiment, when the aspherical surface has an inflection point, it is divided into A area and B area in the x-axis direction with the inflection point as a boundary, and then each is divided. Each area is divided in the z-axis direction individually. Then, in the case of the third example, the area A was divided into 6 in the z-axis direction, and the area B was divided into 4 in the z-axis direction to form the illumination lens shown in cross section in FIG. Here again, the refractive index of the illumination lens is n = 1.883, and each axis y ₂₀₁ , y parallel to the optical axis.
_The angles θ _201a and θ _201b , θ _202a and θ _202b , θ _203a and θ _203b , θ _204a and θ _204b , θ _205a and θ _205b formed by the respective slopes with respect to ₂₀₂ , y ₂₀₃ , y ₂₀₄ and y ₂₀₅ Is as shown in the following table.

When using the illumination optical system of the third embodiment,
It is possible to satisfactorily illuminate a relatively wide range with an observation viewing angle of 100 ° or more.

Here, the illumination lens having the aspherical shape as shown in FIG. 14 is generally poor in workability, and it is difficult to guarantee the surface accuracy in mass production. By replacing the aspherical shape with the V-shaped ring-shaped convex portion as in the third embodiment, the workability is remarkably improved. Yield is improved.

[0032]

As described above in detail with reference to each embodiment, according to the present invention, a light emitting body serving as a light source and an illumination lens arranged in front of an illumination light flux emitting end of the light emitting body are provided.
In an illumination optical system for an endoscope in which an illumination light flux emitted from a light emitter is diffused by an illumination lens, the illumination lenses are adjacent to each other on a light emitter side surface of the lens body on a concentric circle centered on the optical axis. A plurality of strips having V-shaped or V-shaped cross-sections are formed, and these slopes having V-shaped or V-shaped cross-sections are formed under specific conditions. Therefore, in the thus obtained endoscope illumination optical system, it is possible to easily provide a configuration having a relatively wide illumination range and capable of brightly illuminating the peripheral portion of the visual field, and a relatively small loss of light amount. There is a feature.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between an emission angle and an irradiation intensity of an illumination light flux when diffused by an illumination lens through a light guide fiber bundle in a general endoscope illumination optical system.

FIG. 2 is a graph showing a light distribution characteristic of the illumination lens.

FIG. 3 is an operation explanatory view for explaining a light diffusion characteristic depending on a V-shaped sandwiching angle of an illumination lens with a V-shaped annular zone convex portion in the illumination optical system for an endoscope of the present invention.

FIG. 4 is an operation explanatory view for explaining a light diffusion characteristic according to a V-shaped sandwiching angle of an illumination lens with a V-shaped annular zone convex portion in an illumination optical system for an endoscope when the present invention is applied.

5A and 5B are diagrams for explaining conditions for setting a V-shaped holding angle of the illumination lens with the same V-shaped annular zone convex portion.

FIG. 6 is a graph showing the relationship between the slope angle of the V-shaped annular zone convex portion and the refractive index of the lens body in the same illumination lens.

FIG. 7 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope that uses an illumination lens with a V-shaped annular zone convex portion to which the first embodiment of the present invention is applied.

FIG. 8 is an operation explanatory view for explaining a light diffusion characteristic when the illumination lens with a V-shaped annular zone convex portion in the first example is provided with a means for preventing a decrease in illuminance in the peripheral portion of the visual field.

FIG. 9 is a graph showing a light diffusion characteristic of an illumination lens with a V-shaped annular zone convex portion in the illumination optical system for an endoscope in the first example.

FIG. 10 is a graph showing a light diffusion characteristic of the illumination lens with a V-shaped annular zone convex portion in the normal case.

FIG. 11 is a graph showing the light diffusion characteristics of the illumination lens with V-shaped annular zonal convex portions improved by the first example of the same book.

FIG. 12 is a diagram for explaining the conditions and concept when applying the second embodiment of the present invention to a concave lens.

FIG. 13 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope that uses an illumination lens with a V-shaped annular zone convex portion to which a second embodiment of the present invention is applied.

FIG. 14 is a diagram for explaining conditions and ideas when applying the third embodiment of the present invention to an aspherical lens.

FIG. 15 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope that uses an illumination lens with a V-shaped annular zone convex portion to which a third embodiment of the present invention is applied.

FIG. 16 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope using a conventional illumination lens with an inner concave surface.

FIG. 17 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope using a conventional Fresnel lens.

FIG. 18 is an operation explanatory view showing a light diffusion state of the illumination optical system for an endoscope by the Fresnel lens.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Illumination lens 11 Lens main body 11a Outer peripheral part of lens main body 12 V-shaped annular zone 13a One slope of V-shaped annular zone 13b The other slope of V-shaped annular zone 20 Light guide fiber bundle

[Procedure amendment]

[Submission date] July 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

[0027]Second embodiment． Next, FIG. 12 and FIG.
2nd Example of invention is shown. The second embodiment is based on the conventional example.
For the concave lens as shown in FIG.
The present invention is applied. That is, as shown in FIG.
The optical axis is the z-axis with respect to the concave surface of the lens, and
After taking the x-axis perpendicular to the optical axis in the radial direction, the concave surface is the z-axis
Divided into n (n is an even number) areas with an appropriate width Δh in the direction
In addition, the lens surface in each area
The approximate light distribution that contributes is calculated, and this is calculated in this example.
Each slope of the illumination lens due to the V-shaped cross section
Applied to the slope of. And in the case of the second embodiment,
Is divided into 6 areas and the lighting shown in cross section in FIG.
The lens was formed. Here, the refractive index of the illumination lens is n
= 1.883, and each axis y parallel to the optical axis ₁₀₁, y₁₀₂, y
₁₀₃With respect to the angle θ formed by each slope_101aWhen
θ_101b, Θ_102aAnd θ_102b, Θ_103aAnd θ_103bIs as shown in the following table
Is.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0029

[Correction method] Change

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Third Embodiment . 14 and 15 show a third embodiment of the present invention. The third embodiment applies the present invention to an illumination lens having an aspherical surface as shown in FIG. That is, also in this case, as shown in FIG. 14, with respect to the aspherical surface of the lens, the optical axis is taken as the z axis, and the x axis is taken in the radial direction perpendicular to the optical axis, As in the case of the second embodiment, the aspherical surface is divided into n (n is an even number) areas with an appropriate width Δh in the z-axis direction. However, as in the third embodiment, when the aspherical surface has an inflection point, it is divided into an A area and an B area in the x-axis direction with the inflection point as a boundary, and then each is divided. Each area is divided in the z-axis direction individually. Then, in the case of the third example, the area A was divided into 6 in the z-axis direction, and the area B was divided into 4 in the z-axis direction to form the illumination lens shown in cross section in FIG. Here again, the refractive index of the illumination lens is n = 1.883, and each axis y ₂₀₁ , y parallel to the optical axis.
_The angles θ _201a and θ _201b , θ _202a and θ _202b , θ _203a and θ _203b , θ _204a and θ _204b , θ _205a and θ _205b formed by the respective slopes with respect to ₂₀₂ , y ₂₀₃ , y ₂₀₄ and y ₂₀₅ . Is as shown in the following table.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

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As shown in this table, in the third embodiment, the inclination angle of the slope on the optical axis side with respect to the optical axis is
70 °, 43 °, 34 °, 40 °, 34 °, the decreasing tendency turns to the increasing tendency and then decreases again, and the inclination angle of the non-optical axis side slope with respect to the optical axis is
It shows extremely complicated angle changes such as 47 °, 40 °, 37 °, 37 °, 31 °, in which the decreasing tendency stops halfway and then decreases again. Therefore, the angle formed by the V-shaped bi-slopes is 117 °, 8
It is getting smaller and larger like 3 °, 71 °, 77 °, 65 °.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

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When using the illumination optical system of the third embodiment,
It is possible to satisfactorily illuminate a relatively wide range with an observation viewing angle of 100 ° or more. Incidentally, here, the illumination lens having the aspherical shape as shown in FIG. 14 is generally poor in workability, and it is difficult to guarantee the surface accuracy in mass production. By replacing the aspherical shape with the V-shaped ring-shaped convex portion as in the embodiment, the workability is remarkably improved. In the case of adopting the press molding, the manufacturing yield is increased. Is improved.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

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[Brief description of drawings]

FIG. 1 is a graph showing a relationship between an emission angle of an illumination light flux emitted from a light guide fiber bundle and irradiation intensity.

FIG. 2 is a diagram showing a range in which an illumination light flux emitted from a light guide fiber bundle contributes particularly strongly to a light distribution characteristic of an illumination lens.

FIG. 3 is an operation explanatory view for explaining a light diffusion characteristic depending on a V-shaped sandwiching angle of an illumination lens with a V-shaped annular zone convex portion in the illumination optical system for an endoscope of the present invention.

FIG. 4 is an operation explanatory view for explaining a light diffusion characteristic according to a V-shaped sandwiching angle of an illumination lens with a V-shaped annular zone convex portion in an illumination optical system for an endoscope when the present invention is applied.

5A and 5B are diagrams for explaining conditions for setting a V-shaped holding angle of the illumination lens with the same V-shaped annular zone convex portion.

FIG. 6 is a graph showing the relationship between the slope angle of the V-shaped annular zone convex portion and the refractive index of the lens body in the same illumination lens.

FIG. 7 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope that uses an illumination lens with a V-shaped annular zone convex portion to which the first embodiment of the present invention is applied.

FIG. 8 is an operation explanatory view for explaining a light diffusion characteristic when the illumination lens with a V-shaped annular zone convex portion in the first example is provided with a means for preventing a decrease in illuminance in the peripheral portion of the visual field.

FIG. 9 is a graph showing a light diffusion characteristic of an illumination lens with a V-shaped annular zone convex portion in the illumination optical system for an endoscope in the first example.

FIG. 10 shows the light diffusion characteristics of an illumination lens of the present invention in which all the ring-shaped convex portions are formed in the same V-shaped cross section, so that the illumination lens of the present invention illuminates a range of an observation viewing angle of 80 ° or more. It is a graph.

FIG. 11 shows the light diffusion characteristics of an illumination lens of the present invention in which all the annular convex portions are formed in different V-shaped cross sections, so as to illuminate a range of an observation viewing angle of 80 ° or more. It is a graph.

FIG. 12 is a diagram illustrating conditions and ideas when the illumination lens of the present invention is applied to a concave lens.

FIG. 13 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope that uses an illumination lens with a V-shaped annular zone convex portion according to a second example of the present invention.

FIG. 14 is a diagram illustrating conditions and ideas when the illumination lens of the present invention is applied to an aspherical lens.

FIG. 15 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope that uses an illumination lens with a V-shaped annular zone convex portion according to a third example of the present invention.

FIG. 16 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope using a conventional illumination lens with an inner concave surface.

FIG. 17 is an optical system configuration diagram showing an outline of an illumination optical system for an endoscope using a conventional Fresnel lens.

FIG. 18 is an operation explanatory view showing a light diffusion state of the illumination optical system for an endoscope by the Fresnel lens. ─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] July 18, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

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[Figure 5]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

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[Figure 6]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 13

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[Fig. 13]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] Figure 15

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FIG. 15

Claims (2)

[Claims] 1. An endoscope illumination comprising a light emitting body as a light source and an illumination lens arranged in front of the light emitting body, wherein an illumination light flux emitted from the light emitting body is diffused by the illumination lens. In the optical system, the illumination lens has a plurality of annular V-shaped or V-shaped cross-section convex portions that are adjacent to each other on a concentric circle centered on the optical axis on the surface of the lens on the light emitter side. The cross-sectional V-shape or the substantially V-shape of each of the ring-shaped protrusions has an inclination angle θ ₁ with respect to the optical axis of the optical axis side slope, and with respect to the optical axis of the non-optical axis side slope. When the tilt angle is θ ₂ and the refractive index of the lens is n, An illumination optical system for an endoscope, which is formed so as to satisfy the following condition. 2. An illumination lens having a plurality of annular V-shaped or substantially V-shaped annular zone convex portions adjacent to each other on a concentric circle centered on the optical axis on one surface, The V-shaped or substantially V-shaped cross section of each of the ring-shaped convex portions has an inclination angle θ ₁ with respect to the optical axis of the optical axis side slope, and an inclination angle θ ₂ with respect to the optical axis of the non-optical axis side slope. When the refractive index of the lens is n, An illumination lens that is formed so as to satisfy the following conditions.