JP2015112389A - Device for endoscope and endoscope - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for endoscopes and an endoscope capable of distributing light in response to distortion correction.SOLUTION: A device (100, 300, 500, or 600) for endoscopes includes: an insertion part (2); a bending part (1) to be connected to the insertion part (2); an imaging optical system (10) capable of correcting distortion characteristics of a captured image; forward illumination optical systems (31, 32, 33, and 5); rearward illumination optical systems (41, 42, 43, 44, 48, and 49) provided at a position closer to the bending part (1) side than the forward illumination optical systems (31, 32, 33, and 5). The forward illumination optical systems (31, 32, 33, and 5) and the rearward illumination optical systems (41, 42, 43, 44, 48, and 49) independently control light quantities to be emitted. The rearward illumination optical systems (41, 42, 43, 44, 48, and 49) emit illumination light so as to illuminate outside a projection area (Z1) of the insertion part (2) in a visual field (F) of the imaging optical system (10).

Description

  The present invention relates to an endoscope apparatus and an endoscope.

  An endoscope having an illumination unit is used.

  For example, Patent Document 1 discloses an endoscope that has a plurality of illumination units and independently controls the intensity of illumination light. According to such an endoscope, illumination light can be emitted according to the shape inside the subject.

JP 2012-147882 A

  Incidentally, there is a need for an endoscope device and an endoscope that can obtain light distribution according to distortion correction.

  Here, an example of a phenomenon that occurs when distortion correction is performed on a predetermined image will be described. For example, as shown in FIG. 13, the endoscope 900 emits illumination light forward from the insertion portion 901. The illumination light illuminates substantially circular regions D1, D2, D3, and D4 centering on the emission axis C9 on the imaging surface F0. The diameter gradually increases in the order of the regions D1, D2, D3, and D4. In the regions D1, D2, D3, and D4, the illuminance decreases according to the distance from the emission axis C9. Here, the image I1 captured by the endoscope 900 is displayed on the screen of the display device without performing distortion correction. Then, as shown in FIG. 14, the image I1 distorted so that the areas D1, D2, D3, and D4 expand from the center C is displayed on the screen.

  Subsequently, distortion correction is performed on the image I1. Then, as shown in FIG. 15, the distortion is corrected so that the outer edges of the regions D1, D2, D3, and D4 in the image I1 (see FIG. 14) approach the center C, and the image I2 is displayed on the screen. Accordingly, in the image I2, the area D1 at the center of the screen is reduced, and the area at the periphery of the screen, for example, the area D4 is projected as if it has been expanded.

  Here, in the area around the imaging surface F0, the illuminance decreases in proportion to the cosine fourth law as compared to the area near the center of the imaging surface F0. That is, the illuminance decreases in the regions D2, D3, and D4 sequentially with respect to the region D1. Therefore, the region D1 becomes relatively small, and the regions D2, D3, and D4 become relatively large. As a result, the dark region of the screen increases due to distortion correction, giving the user the impression that the light distribution has deteriorated.

  This cannot be solved by increasing the amount of illumination light. This is because if the sufficient illuminance is obtained for the peripheral region in the image I2, the central region D1 is over-exposed (halated) due to excessive light quantity. As a result, the user must switch the illumination each time the center and the periphery of the image are observed, which is very burdensome for the user.

  In addition, the above-described problem cannot be solved with the configuration of the endoscope disclosed in Patent Document 1 by using relatively strong illumination light in which the area around the image is relatively stronger than the area at the center of the image. . This is because if the above-mentioned illumination is emitted in order to keep the peripheral area of the image where the illuminance has been reduced by the distortion correction to the same level as before the distortion correction, the central area of the image becomes brighter and the peripheral area of the image becomes brighter. This is because the center of the image is skipped.

This will be explained in detail as follows. For example, consider an objective lens having a half field angle of 75 ° and a distortion of fsinθ as used in a normal endoscope. That is, the focal length of the objective lens is f, the image height from the image center is h, and the incident angle of the principal ray at the image height is θ. In this optical system, h = fsinθ holds. The illuminance ratio En (h) with respect to the center of the image at that position is En (h) = cos ⁴ (sin ⁻¹ (h / f)) according to the cosine fourth law.
It is expressed. On the other hand, if this is completely corrected so that there is no distortion, the illuminance ratio En (h) changes to Ec (h). If the constant determined from the angle of view is A, the illuminance ratio Ec (h) is
Ec (h) = cos ⁴ (tan ⁻¹ (Ah / f))
It is expressed.
FIG. 16 shows the relationship between the illuminance ratios En (h) and Ec (h) with the image height ratio and the illuminance ratio as axes.

  It can be seen from FIG. 16 that the improvement in illuminance at the center portion of the image appears significantly greater than the improvement in illuminance at the peripheral portion of the image by distortion correction. In other words, even if an attempt is made to illuminate the peripheral portion of the image with the configuration of the endoscope disclosed in Patent Document 1, the illuminance improvement in the central portion of the image appears more significantly than the illuminance improvement in the peripheral portion of the image, and eventually the periphery of the image The problem of darkness cannot be solved.

  The present invention has been made against the background described above, and an object of the present invention is to provide an endoscope apparatus and endoscope that can obtain light distribution according to distortion correction.

An endoscopic device according to the present invention includes:
An insertion part to be inserted into the subject;
A bending portion coupled to the insertion portion;
An imaging optical system capable of correcting distortion characteristics of the captured image;
A front illumination optical system provided at a distal end portion (for example, one end portion) of the insertion portion;
A rear illumination optical system provided at a position closer to the curved portion than the front illumination optical system, and
The front illumination optical system and the rear illumination optical system independently control the amount of light emitted,
The rear illumination optical system emits illumination light so as to irradiate the outside of the projection area of the insertion portion within the field of view of the imaging optical system.

  According to such a configuration, light distribution according to distortion correction can be performed.

Further, when an area irradiated by the front illumination optical system in the field of view of the imaging optical system is an irradiation area (for example, the area Z2), the emission axis of the rear illumination section passes through the inside of the irradiation area. It may be a feature. The imaging optical system includes an objective lens, the half angle of view of the objective lens is ω, the distance between the imaging target and the tip is d, and the back illumination system emits the illumination light. In the imaging surface of the imaging target, if the distance from the optical axis of the objective lens to the position where the illuminance is maximum is Δ (d) and the observation distance at which the maximum resolution of the objective lens is obtained is dN,
It is good also as satisfy | filling the formula represented by these. Further, in the in-plane Δ (dN) of the observation distance dN, if the illuminance by the front illumination optical system is If and the illuminance by the rear illumination optical system is Ib, 2 ≦ Ib / If may be satisfied. . Furthermore, Ib / If ≦ 8 may be satisfied.

  On the other hand, an endoscope according to the present invention is an endoscope having the above-described endoscope device.

  ADVANTAGE OF THE INVENTION According to this invention, the apparatus for endoscopes and endoscope which can perform light distribution according to distortion correction can be provided.

1 is a perspective view of an endoscope apparatus according to a first embodiment. 1 is a schematic diagram of a main part of an endoscope apparatus according to a first embodiment. It is a distribution map of illuminance ratio. FIG. 6 is a schematic diagram of a main part of an endoscope apparatus according to a second embodiment. It is a table | surface which shows an imaging body distance and various distances. FIG. 10 is a schematic diagram of a main part of an endoscope apparatus according to a third embodiment. FIG. 10 is a perspective view of an endoscope apparatus according to a fifth embodiment. FIG. 10 is a schematic diagram of a main part of an endoscope apparatus according to a fifth embodiment. FIG. 10 is a perspective view of an endoscope apparatus according to a sixth embodiment. FIG. 10 is a side view of an endoscope apparatus according to a sixth embodiment. It is a distribution map of illuminance ratio. It is a table | surface which shows an imaging body distance and various distances. It is a schematic diagram of a related endoscope. It is a schematic diagram which shows the image obtained using a related endoscope. It is a schematic diagram which shows the image obtained using a related endoscope. It is a figure showing the illumination distribution before distortion correction and after correction | amendment.

Embodiment 1 FIG.
With reference to FIG.1 and FIG.2, the endoscope concerning Embodiment 1 is demonstrated. FIG. 1 is a perspective view of an endoscope apparatus according to the first embodiment. FIG. 2 is a schematic diagram of a main part of the endoscope apparatus according to the first embodiment.

As shown in FIG. 1, the endoscopic device 100 includes a bending portion 1 and an insertion portion 2 connected to an end portion of the bending portion 1. The endoscope apparatus 100 is used by being attached to an endoscope. The endoscopic device 100 can send a signal regarding a captured image to an external display device. Further, the endoscope has an image processing unit that can correct distortion of an image, that is, a distortion characteristic of the image. The image processing unit performs distortion correction on the captured image, and the display device displays the corrected image. Here, the distortion correction may be a complete correction for completely correcting the distortion or a reduction correction for reducing the absolute value of the generated distortion.

  The bending portion 1 is a string-like body that can be bent according to the shape inside the subject. Further, the bending portion 1 has a cable or the like for transmitting and receiving electricity and signals to an image pickup device and a lighting device mounted on the insertion portion 2.

  The insertion part 2 has the other end part 22 connected to the bending part 1 and one end part 21 assembled to the other end part 22.

  The one end portion 21 is a substantially cylindrical body having front illumination portions 31 and 32 and the imaging unit 10. The front illumination units 31 and 32 are illumination elements having a predetermined light distribution angle θ, and are, for example, LEDs (Laser Emitting Diodes). Although not shown in the figure, a transparent cover may be attached for the purpose of improving insertion property and chemical resistance. Of course, this transparent cover may have refractive power in order to increase the light diffusibility. In addition to the LED, the illumination element may be a lens system that diffuses light from the end of the light guide fiber, or may be one using fluorescent glass. The front illumination units 31 and 32 are provided on the top surface of the tip of the one end 21. The imaging unit 10 includes an objective lens, an imaging element, and the like, and can capture an image in a direction parallel to the optical axis A1. The front illumination units 31 and 32 are provided at symmetrical positions with respect to the optical axis A1 of the imaging unit 10. The front illumination units 31 and 32 can control the amount of light independently of each other. The emission axes of the front illumination units 31 and 32 are parallel to the optical axis A1. Note that the emission axes of the front illumination units 31 and 32 may be inclined from the optical axis A1.

  The other end 22 is a substantially cylindrical body made of a transparent material. Back illumination portions 41, 42, 43, 44 are provided on the inner peripheral surface of the other end portion 22 or in the vicinity thereof. The rear illumination units 41, 42, 43, 44 are evenly arranged on the edge of the virtual circle centered on the optical axis A <b> 1 of the imaging unit 10. The rear illumination units 41, 42, 43, and 44 are illumination elements having a predetermined light distribution angle θ2, and are, for example, LEDs. The light distribution angle θ2 may be smaller than the light distribution angle θ. The back illumination units 41, 42, 43, and 44 can control the light amount independently. The emission axes C1 of the rear illumination units 41, 42, 43, and 44 are inclined from the optical axis A1 of the imaging unit 10, respectively. The illumination light from the rear illumination units 41, 42, 43, 44 passes through the other end portion 22 and is emitted to the outside of the endoscope device 100, but refraction by the other end portion 22 does not occur. Or hardly occur. The front illumination units 31 and 32 and the rear illumination units 41, 42, 43, and 44 are supplied with electricity by cables or the like inside the bending unit 1.

  Next, an example of the positions and orientations of the rear illumination units 41, 42, 43, and 44 will be described with reference to FIG. As shown in FIG. 2, a region obtained by projecting a cross-sectional shape perpendicular to the longitudinal direction of the insertion portion 2 onto the imaging surface F is denoted by Z1, a region irradiated by the front illumination unit 32 on the imaging surface F is denoted by Z2, and the rear illumination unit 41. , 42, 43, and 44 are areas Z3 to be irradiated. Then, the positions and orientations of the rear illumination units 41, 42, 43, and 44 are adjusted so that the region Z3 is located outside the region Z1. In FIG. 2, the illumination light of the rear illumination unit 42 is illustrated for easy understanding, and illustration of illumination light of the rear illumination units 41, 43, 44 is omitted. Further, the distance from the front illumination unit 32 to the imaging surface F and the light distribution angle θ are determined so that the region Z2 is larger than the region Z1.

  Further, the positions and orientations of the rear illumination units 41, 42, 43, and 44 are adjusted so that the emission axes of the rear illumination units 41, 42, 43, and 44 pass between the region Z1 and the region Z2.

Calculation example.
Next, a calculation example of the illuminance distribution obtained when the endoscope apparatus according to the first embodiment is used will be described with reference to FIG. FIG. 3 is a distribution diagram of the illuminance ratio.

  An imaging device having a planar portion was imaged using the endoscope apparatus 100. Specifically, imaging is performed with the position and orientation of the endoscope apparatus 100 fixed so that the optical axis A1 of the imaging section 10 of the endoscope apparatus 100 intersects the planar portion of the imaging body perpendicularly. . The rear illumination units 41, 42, 43, and 44 emit illumination light with a light amount Rb, and the front illumination units 31 and 32 emit illumination light with a light amount Rf. Here, the light amounts Rb and Rf were adjusted so that Rb / Rf> 1. In such a case, the calculation result of the illuminance distribution of the imaged screen is shown in FIG.

  As shown in FIG. 3, in the area E1 near the center of the screen, the illuminance is small and dark. On the other hand, in the area E2 at the periphery of the screen, the illuminance is large and bright. That is, the illumination is hollow, and even if distortion correction is performed, the peripheral portion of the screen can be brightened without causing the central portion of the screen to be blown out.

  As described above, according to the first embodiment, the distortion correction is completely corrected or reduced by independently controlling the illumination by the front illumination unit and the illumination by the rear illumination unit and adjusting the direction and position of the rear illumination unit. Irrespective of correction, light distribution according to distortion correction can be performed.

  Further, according to the first embodiment, the front illumination unit and the rear illumination unit are installed as illumination optical systems so that illumination light can be emitted at a predetermined emission angle. Thereby, the insertion part of a small diameter can be employ | adopted and the insertion to the inside of a subject can be performed smoothly.

Embodiment 2. FIG.
Next, the endoscope apparatus according to the second embodiment will be described with reference to FIGS. The endoscope apparatus according to the second embodiment differs from the endoscope apparatus according to the first embodiment only in the directions of the front illumination unit and the rear illumination unit. The other configurations are common and will not be described. FIG. 4 is a schematic diagram of a main part of the endoscope apparatus according to the second embodiment. FIG. 5 is a table showing the imaging body distance and various distances.

  Here, the front illumination unit 32 and the rear illumination unit 42 will be described as examples. As illustrated in FIG. 4, the front illumination unit 32 emits illumination light having a light distribution angle θ toward the imaging body F0. On the imaging surface F, illumination light with a light distribution angle θ irradiates the region Z23. Further, the illumination light has a light beam having a light distribution angle from 0 to θ / 2. On the imaging surface F, this light beam irradiates the area Z21. The rear illumination unit 42 is installed so that the emission axis C1 of the rear illumination unit 42 passes through the region Z22 between the regions Z21 and Z23. Here, the regions Z22 and Z23 receive illumination light from the rear illumination unit 42 although the amount of illumination light by the front illumination unit 32 is smaller than that of the region Z21. That is, since the regions Z21, Z22, and Z23 obtain a good light distribution, the light distribution according to the distortion correction can be performed more reliably and stably.

Here, the case where the emission axis C1 of the back illumination part 42 passes the area | region Z22 is demonstrated more concretely. The distance from the optical axis A1 to the point P1 on the outer edge of the region Z21 is L1. Further, the distance from the optical axis A1 to the intersection P2 between the emission axis C1 and the imaging surface F is L2. Further, the distance is L3 from the optical axis A1 to the point P3 on the outer edge of the region Z23. When the following mathematical formula 1 is established, the emission axis C1 of the rear illumination unit 42 passes through the region Z22.
L1 <L2 <L3 (Formula 1)
Specifically, the distances L1, L2, and L3 are represented by the following formulas 2, 3, and 4, respectively.
L1 = d1 × tan (θ / 2) (2)
L2 = (d1 + d2) × tan (α) (Formula 3)
L3 = d1 × tan (θ) (Equation 4)
Image pickup body distance d1: Distance from the front illumination unit 32 to the image pickup body [mm]
Distance between illumination parts d2: Distance from front illumination part 32 to rear illumination part 42 [mm]
Output angle α: angle [°] at which the optical axis A1 and the output axis C1 intersect
In order for Formula 1 to hold, it is only necessary to appropriately determine the imaging body distance d1, the inter-illuminator distance d2, the emission angle α, and the light distribution angle θ. If these are appropriately determined, as described above, the light distribution according to the distortion correction can be performed more reliably and stably.

  A more specific example will be described. Here, when the distance between the illumination parts d2 = 10 [mm], the emission angle α = 40 [°], and the light distribution angle θ = 140 [°], the imaging body distance d1 = 5, 10, The distances L1, L2, and L3 at 100 [mm] were determined.

  The obtained results are shown in FIG. As shown in FIG. 5, the distance L1 <L2 <L3 is established regardless of whether the imaging body distance d1 [mm] is 5, 10, or 100. That is, in any case, it is considered that light distribution according to distortion correction can be performed.

Embodiment 3 FIG.
Next, the endoscope apparatus according to the third embodiment will be described with reference to FIG. The endoscope apparatus according to the third embodiment is different from the endoscope apparatus according to the first embodiment only in the position and orientation of the rear illumination unit. The other configurations are common and will not be described. FIG. 6 is a schematic diagram of a main part of the endoscope apparatus according to the third embodiment.

  As shown in FIG. 6, the imaging unit 10 of the endoscope apparatus 300 includes an objective lens 11. On the imaging surface F, the outer edge of the region Z31 imaged at a half angle of the half field angle ω of the objective lens 11, that is, ω / 2, and the region Z33 imaged at the half field angle ω of the objective lens 11. There is a region Z32 surrounded by the outer edge. The position and inclination of the rear illumination unit are determined so that the emission axis C1 passes through the region Z32. In the case where only the front illumination unit emits illumination light, in the region Z32, when distortion correction is performed, it looks particularly dark. When the illumination light from the rear illumination unit is emitted in addition to the illumination light from the front illumination unit, the illuminance of the region Z32 can be increased and a good light distribution can be realized. It is preferable that the half angle of view ω of the objective lens 11 and the light distribution angle θ of the front illumination unit are the same or substantially the same. Here, “substantially the same” means that the error is within 10%.

Specifically, the position and inclination of the rear illumination unit are determined so that the following Expression 5 is satisfied.
ω: Half angle of view of objective lens Δ (d): From the position having the distance d from the objective lens to the optical axis of the objective lens from the position where the illuminance becomes maximum in the imaging plane when the rear illumination unit emits light Distance dN: Observation distance at which the maximum resolution of the objective lens can be obtained

  As described above, according to the endoscope according to the third embodiment, similarly to the endoscope according to the first embodiment, light distribution according to distortion correction can be performed.

Embodiment 4 FIG.
Next, an endoscope apparatus according to a fourth embodiment will be described. The endoscope apparatus according to the fourth embodiment is different from the endoscope apparatus according to the first embodiment in the front illumination unit and the rear illumination unit. The other configurations are common and will not be described.

In the in-plane Δ (dN) of the observation distance dN, if the illuminance by the front illumination unit is If and the illuminance by the rear illumination unit is Ib, the positions of the front illumination unit and the rear illumination unit so as to satisfy Equation 6 below. Determine the direction, light distribution angle, light quantity, etc. It is preferable that the rear illumination unit can satisfy the following Expression 6 more reliably if it can emit a larger amount of light compared to the front illumination unit. Note that the illuminance If from the front illumination unit and the illuminance Ib from the rear illumination unit may each use the maximum value in the in-plane Δ (dN) as a representative value in order to simplify the calculation.
Ib / If ≧ 2 (Formula 6)
If: Illuminance by the front illumination unit Ib: Illuminance by the rear illumination unit

Moreover, it is preferable to determine the position, direction, light distribution angle, light quantity, and the like of the front illumination unit and the rear illumination unit so as to satisfy the following Expression 7.
Ib / If ≦ 8 (Expression 7)
When the front illumination unit and the rear illumination unit satisfying Expression 7 are used, it is possible to perform light distribution according to distortion correction using an illumination unit having appropriate performance.

  Here, an example of a detailed configuration of the endoscope apparatus according to the third and fourth embodiments will be described. As shown in FIG. 1, an XYZ orthogonal coordinate system is defined with the optical axis A1 as the Z axis. The coordinates (X, Y, Z) of the front illumination units 31 and 32 are (± 7, 0, 0). Further, the coordinates (X, Y, Z) of the rear illumination units 41, 42, 43, 44 are (± 5, ± 5, −15). The emission axis of the illumination light from the front illumination units 31 and 32 is parallel to the optical axis A1 (Z axis). The light distribution angle θ of illumination light by the front illumination units 31 and 32 is 140 °. The emission angle α of the rear illumination units 41, 42, 43, 44 is 40 °, and the azimuth angle of the rear illumination units 41, 42, 43, 44, that is, the Y axis and the rear illumination units 41, 42, 43, 44. The angles formed by the emission axes of the illumination light are ± 15 and ± 165 °. The diameter of the insertion part 2 is φ20 mm. As for d1, the imaging body distance d1 is 30 mm.

Embodiment 5 FIG.
Next, the endoscope according to the fifth embodiment will be described with reference to FIGS. FIG. 7 is a schematic diagram of an endoscope apparatus according to a fifth embodiment. FIG. 8 is a schematic diagram of a main part of the endoscope apparatus according to the fifth embodiment. FIG. 8 is a view in which one end 21 is removed from the endoscope apparatus 500 shown in FIG. Compared with the endoscope apparatus 100 according to the first embodiment, the endoscope apparatus 500 according to the fourth embodiment is connected to the front illumination unit instead of the front illumination units 31 and 32 as a front illumination optical system. It differs only in the place using a light plate. The other configurations are common and will not be described.

  As shown in FIG. 7, the endoscope apparatus 500 includes a light guide plate 5. The light guide plate 5 is an annular body or a semi-annular body made of a transparent material. The light guide plate 5 has a stepped surface that bends in a stepped manner on the upper surface. The light guide plate 5 is installed at the tip of the one end 21. In the endoscope apparatus 500, a light guide plate having a stepped surface that is bent in a stepped shape on the lower surface may be used instead of the light guide plate 5. When using such a light guide plate, it is preferable to apply a mirror coat to the light guide plate.

  As shown in FIG. 8, a front illumination unit 33 is installed inside the one end 21 on the side surface of the light guide plate 5, and illumination light can be emitted in the circumferential direction of the light guide plate 5. The emitted illumination light is reflected on the bottom surface of the light guide plate 5, travels in the direction along the optical axis A 1, and exits from the top surface of the light guide plate 5 to the outside of the light guide plate 5.

  The endoscopic device 500 has a uniform light distribution angle from the upper surface of the light guide plate 5 having a large area as compared with the front illumination units 31 and 32 of the endoscopic device 100 according to the first embodiment. It is possible to emit simple illumination light.

  As described above, according to the endoscope apparatus according to the fifth embodiment, similarly to the endoscope apparatus 100 according to the first embodiment, it is possible to obtain a light distribution according to the distortion correction.

Embodiment 6 FIG.
Next, the endoscope according to the sixth embodiment will be described with reference to FIGS. FIG. 9 is a schematic diagram of an endoscope apparatus according to a sixth embodiment. FIG. 10 is a side view of the endoscope apparatus according to the sixth embodiment. As compared with the endoscope apparatus 100 according to the first embodiment, the endoscope apparatus 600 according to the sixth embodiment is used as a rear illumination optical system instead of the rear illumination units 41, 42, 43, and 44. It differs only in the place where the light guide fiber bundle and the inclined mirror are used. Other configurations are almost the same, and a description thereof will be omitted. 9 and 10, the emission axes of the front illumination units 31 and 32 are inclined so as to be separated from the optical axis A1.

  As shown in FIG. 9, the endoscope apparatus 600 includes a light guide fiber bundle 48 and an inclined mirror 49. The inclined mirror 9 has a surface that is inclined so that its diameter decreases from the top to the bottom. The upper part of the inclined mirror 49 is connected to the one end 21. The inclined mirror 49 is located above or above the light guide fiber bundle 48. More specifically, the light guide fiber bundle end surface 481 is positioned below the inclined mirror 49. An annular transparent cover 23 made of a transparent material is attached around the inclined mirror 49. The transparent cover 23 is connected to the lower part of the one end 21.

  The light guide fiber bundle 48 has a hollow cylindrical shape. The light guide fiber bundle 48 can guide light from an external illumination unit (not shown) and emit the light from the end surface 481 of the hollow circular light guide fiber bundle. The light emitted from the end face 481 of the light guide fiber bundle is reflected by the inclined mirror 49 and emitted from the transparent cover 23 to the outside of the endoscope device 600.

Calculation example.
Next, a calculation example of the illuminance distribution obtained when the endoscope apparatus according to the first embodiment is used will be described with reference to FIG. FIG. 11 is a distribution diagram of the illuminance ratio.

  Using the endoscope apparatus 600, an imaging body having a planar portion was imaged under the same conditions as in the calculation example according to the first embodiment. In such a case, the calculation result of the illuminance distribution of the imaged screen is shown in FIG.

  As shown in FIG. 11, in the area E61 near the center of the screen, the illuminance is small and dark. On the other hand, in the area E62 at the periphery of the screen, the illuminance is large and bright. That is, the illumination is hollow, and even if distortion correction is performed, the peripheral portion of the screen can be brightened without causing the central portion of the screen to be blown out.

  The endoscope apparatus 600 is arranged in the circumferential direction of the endoscope, particularly the insertion section 2, as compared with the front illumination sections 31 and 32 of the endoscope apparatus 100 (see FIG. 1) according to the first embodiment. On the other hand, not only can the illumination be uniform and uniform, but also a light source such as an illumination unit can be provided outside, so that the diameter of the endoscope, particularly the insertion portion 2, can be increased while increasing the amount of emitted light. Can be configured without.

  An example of a more detailed configuration will be described. The light guide fiber bundle end surface 481 has a hollow circular shape with an inner diameter of φ11 and an outer shape of φ16. The inclined mirror 49 is inclined by 48 ° with respect to the optical axis A1 of the endoscope apparatus 600 so as to reflect light toward the outside of the endoscope apparatus 600. For example, when an inclined mirror having a maximum outer diameter of φ18 is used as the inclined mirror 49, the light ray that illuminates the innermost part of the visual field among the light rays reflected by the inclined mirror surface is 64 ° with respect to the optical axis A1 of the endoscope apparatus 600. With a slope of

  The obtained results are shown in FIG. FIG. 12 is a table showing the imaging body distance and various distances. As shown in FIG. 12, the distance L1 <L2 <L3 is established regardless of whether the imaging body distance d1 [mm] is 10, 20, or 100. That is, in any case, it is considered that light distribution according to distortion correction can be performed.

  Here, an example of a more detailed configuration will be described. When the XYZ orthogonal coordinate system shown in FIG. 1 is defined, the coordinates (X, Y, Z) of the front illumination units 31 and 32 are (± 7, 0, 0). The emission axes of the front illumination units 31 and 32 are inclined ± 8 ° with respect to the Z axis. The inner diameter of the light guide fiber bundle 48 is 11 mm, and the outer diameter is 16 mm. The coordinates (X, Y, Z) of the tilting mirror 49 are (± 7, 0, −10). When the Z coordinate is −10 mm, the outer diameter of the inclined mirror 49 is φ18, for example. As the Z coordinate decreases from −10 mm, the mirror surface of the tilt mirror 49 tilts so that the outer diameter of the tilt mirror 49 decreases. The NA (Numerical Aperture) at the exit end of the light guide fiber bundle 48 is 120 °.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, you may change suitably the number of a front illumination part and a back illumination part, a light distribution angle, etc. FIG. Moreover, the back illumination part may be installed in the position of the one end part, especially a curved part rather than a front illumination part. Furthermore, in the embodiment, a uniform and continuous illuminance distribution can be obtained in the circumferential direction of the endoscope using a diffusing plate or a light guide plate even for a system constituted by a finite number of discrete illumination systems. It is good also as such.

1 bending part, 2 insertion part, 5 light guide plate, 10 imaging part,
11 objective lens, 21 one end, 22, 23 other end (transparent cover),
31, 32, 33 Front illumination part 41, 42, 43, 44 Rear illumination part,
48 light guide fiber bundle, 49 tilt mirror,
100, 300, 500, 600 Endoscopic device, A1 optical axis,
C1 emission axis, d1 imaging body distance, d2 distance between illumination parts,
dN observation distance, F imaging surface, I1, I2 image,
L1, L2, L3 distance, P1, P2, P3 points, Rb, Rf light quantity,
E1, E2, Z1, Z2, Z21, Z23 region,
α Output angle, θ, θ2 Light distribution angle, ω Half angle of view.

Claims (6)

An insertion part to be inserted into the subject;
A bending portion coupled to the insertion portion;
An imaging optical system capable of correcting distortion characteristics of the captured image;
A front illumination optical system provided at the distal end of the insertion portion;
A rear illumination optical system provided at a position closer to the curved portion than the front illumination optical system, and
The front illumination optical system and the rear illumination optical system independently control the amount of light emitted,
The apparatus for endoscope which emits illumination light so that the back illumination optical system may irradiate the outside of the projection area of the insertion part within the field of view of the imaging optical system. When the area illuminated by the front illumination optical system within the field of view of the imaging optical system is an irradiation area,
The endoscope apparatus according to claim 1, wherein an emission axis of the rear illumination optical system passes inside the irradiation region. The imaging optical system includes an objective lens,
The half angle of view of the objective lens is ω,
The distance between the imaging target and the tip is d,
When the rear illumination optical system emits light, the distance from the optical axis of the objective lens to the position where the illuminance is maximum is Δ (d) in the imaging surface of the imaging target,
If the observation distance at which the maximum resolution of the objective lens is obtained is dN,
The endoscopic device according to claim 1, wherein: In the in-plane Δ (dN) of the observation distance dN,
Illuminance by the front illumination optical system is If,
When the illuminance by the rear illumination optical system is Ib,
2 ≦ Ib / If
The endoscope apparatus according to claim 1, wherein: Ib / If ≦ 8
The endoscope apparatus according to claim 4, wherein:   An endoscope comprising the endoscope device according to any one of claims 1 to 5.