Illumination device for an endoscope

Abstract

An endoscope tip has an objective lens imaging a field of view; and an illumination device illuminating the field of view, wherein the field of view of the objective lens is larger than 180°; the illumination device is arranged around the objective lens in a top view; the illumination device comprises a transparent cap from which illumination light is emitted into the field of view; the illumination device comprises one or more light emitting devices emitting the emission light; and: - for one light emitting device, a centroid of an angular distribution of the emission light is in a direction tilted away from the optical axis; or - a reflective surface reflects the emission light at least in a direction further away from the optical axis than a direction in which the emission light is incident on the reflective surface.

Description

[0001] This invention relates to an illumination device for an endoscope. In particular, this invention relates to an illumination device for an endoscope having an objective lens with a wide field of view, especially a field of view greater than 180°. Background Technology

[0002] An endoscope's illumination system may include multiple LEDs arranged around the objective lens. The light-emitting devices are typically positioned in a plane perpendicular to the objective lens's optical axis, and are configured to emit light parallel to the optical axis. More precisely, the centroid of the emission angular distribution is located along the optical axis. The light from the LEDs passes through a transparent cap, which then illuminates the field of view. This transparent cap defines the illumination device towards the object space containing the objective lens's field of view.

[0003] The problem the invention aims to solve

[0004] Ideally, such as Figure 1 As shown in the shadowed area at a 180° angle, the field of view of the objective lens of the endoscope with the imaging system is illuminated as uniformly as possible. Figure 2 As shown, if the objective lens has a viewing angle greater than 180° and the LED is a Lambertian emitter that emits light directly onto the transparent cap along the optical axis, substantially uniform field-of-view illumination cannot be achieved. Figure 2 In the diagram, the solid line represents the radiation field of the Lambert emitter.

[0005] Solution to the problem

[0006] This invention provides an endoscope tip or capsule endoscope having an objective lens for imaging the field of view; and

[0007] An illumination device for illuminating the field of view with illumination light, wherein

[0008] The objective lens has an optical axis;

[0009] The objective lens has a field of view greater than 180°;

[0010] In a top view along the optical axis, the illumination device is arranged around the objective lens;

[0011] The lighting device includes a transparent cap from which illumination light is emitted into the field of view;

[0012] The lighting device includes one or more light-emitting devices, each light-emitting device being configured to emit its own emitted light from its respective light-emitting surface; and

[0013] The lighting device satisfies at least one of the following conditions:

[0014] At least one of the light-emitting devices is configured such that the centroid of the angular distribution of the respective emitted light is located in a direction with an angle of inclination greater than or equal to 5° and less than or equal to 85° with respect to the optical axis; and

[0015] The lighting device includes a reflective surface that reflects at least a portion of the emitted light in a direction further away from the optical axis than a portion of the emitted light is incident on the reflective surface.

[0016] Invention Effects

[0017] Even with an objective lens angle of view greater than 180°, substantially uniform objective lens field of view illumination can be achieved through an illumination device. "Substantially uniform" means that the light intensity across the entire angle of view is between 50% and 100% of the maximum light intensity (preferably between 75% and 100% of the maximum light intensity). Furthermore, some embodiments are relatively simple and space-saving. In some cases, light refraction components can be omitted (if the minimum possible refraction at the transparent cover is ignored), which simplifies manufacturing and is therefore cost-effective. Attached Figure Description

[0018] Figure 1 The required profile for objective lens field-of-view illumination uniformity is shown;

[0019] Figure 2 This illustrates how a Lambert emitter illuminates the field of view according to existing technology;

[0020] Figure 3 An endoscope tip with an objective lens is shown, in which an illumination device according to an embodiment of the present invention can be mounted;

[0021] Figure 4 The endoscope tip according to the prior art is shown;

[0022] Figure 5 It shows the location Figure 4 The field of view of the objective lens at the tip of the endoscope;

[0023] Figure 6 Comparison Figure 4 The angle of view of the objective lens in the tip of the endoscope and the emission angle of the illumination;

[0024] Figure 7 It shows Figure 4 A top view of the LED at the tip of the endoscope;

[0025] Figure 8 It shows Figure 4 Radiation pattern at the tip of the endoscope;

[0026] Figure 9 This shows possible arrangements of LEDs in the tip of an endoscope;

[0027] Figure 10 It shows Figure 9 Radiation pattern at the tip of the endoscope;

[0028] Figure 11 The endoscope tip according to a first embodiment of the present invention is shown;

[0029] Figure 12 It shows that according to Figure 11 Cross-sectional and top views of the components of the endoscope tip;

[0030] Figure 13 Comparison Figure 11 The illumination emission angle of the endoscope tip and the aperture angle of the objective lens;

[0031] Figure 14 It shows Figure 11 Radiation pattern at the tip of the endoscope;

[0032] Figure 15 An endoscope tip according to a second embodiment of the present invention is shown;

[0033] Figure 16 It shows that according to Figure 15 Cross-sectional and top views of the components of the endoscope tip;

[0034] Figure 17 Comparison Figure 15 The illumination emission angle of the endoscope tip and the aperture angle of the objective lens;

[0035] Figure 18 It shows Figure 15 Radiation pattern at the tip of the endoscope;

[0036] Figure 19 This illustrates the principle of shadows in the tip of an endoscope according to the prior art;

[0037] Figure 20 This illustrates how, according to the second embodiment, the external field of view can be illuminated with shielded light;

[0038] Figure 21 A reference configuration is shown to explain the principles of embodiments of the present invention; and

[0039] Figure 22 An embodiment of the present invention is shown to explain the principles of the embodiments of the present invention. Detailed Implementation

[0040] Figure 3An example of an endoscope tip 10 is shown, in which an objective lens 1 (preferably a wide-angle objective lens with a viewing angle greater than 180°) is arranged. The optical axis 11 of the objective lens 1 may extend parallel to the axis of symmetry of the endoscope tip 10. In particular, the optical axis 11 of the objective lens 1 may be aligned with or offset from the axis of symmetry of the endoscope tip 10. However, as... Figure 3 As shown in the example, the optical axis 11 can also be tilted relative to the axis of symmetry of the endoscope tip 10.

[0041] In a top view at the distal end of the endoscope tip, the illumination device is mounted around the objective lens 1. For example, it can be mounted directly around the objective lens 1 or spaced apart from it. The illumination device can be rotationally symmetrical. If the illumination device is rotationally symmetrical, its axis of rotation is preferably (but not necessarily) aligned with the optical axis 11 of the objective lens 1.

[0042] In the following explanation, the invention will be described with reference to the endoscope tip 10, wherein the objective lens 1 is mounted axially symmetrically about the endoscope tip 10, and the illumination is mounted rotationally symmetrically about the optical axis of the objective lens 1. However, the invention is not limited to this specific configuration as described above.

[0043] Figure 4 An endoscope tip according to prior art is shown. An objective lens with a viewing angle greater than 180° is located in the endoscope tip. The viewing angle (“aperture angle optics”) is as follows: Figure 5 As shown. Due to the large aperture angle of the optical components, the objective lens should be located at the tip of the endoscope, while all other components (endoscope cap, illumination) should be placed behind it to avoid appearing in the field of view.

[0044] The endoscope tip may also include a camera to capture images of the field of view captured by the objective lens. The camera may have, for example, a CCD chip or a CMOS chip as a sensor. The endoscope tip may also include a portion of relay optics instead of a camera to guide the images captured by the objective lens to the proximal end of the endoscope.

[0045] The endoscope tip also includes an illumination device for illuminating the objective's field of view (or the object space containing the field of view). An LED is mounted in the illumination device that illuminates the object space through the transparent cap (endoscope cap). The cap is transparent if the cap's transparency is at least 75%, preferably at least 90%, and more preferably at least 95%, for all wavelengths emitted at least 50% of the LED's maximum intensity as a function of wavelength. The cap should not be tinted. That is, the difference in transparency between different wavelengths should not exceed 20%, preferably not more than 10%. If the LED also emits light with wavelengths outside the visible light range (400 nm to 800 nm), the above conditions apply to wavelengths within the visible light range but not to wavelengths outside the visible light range.

[0046] The refractive power of a cap is typically very small because it is essentially like a flat parallel plate. The refractive power can vary locally. For example, the maximum local refractive power can be 2dpt(2m). -1 ), preferably 1dpt(1m -1 More preferably 0.5dpt(0.5m) -1 However, in some embodiments of the invention, the cap may be configured as a refractive lens to direct illumination light into a predetermined area of ​​the field of view.

[0047] LEDs can be of the same type or different types. For example, two different types can be used to illuminate two different colors of object space. In this case, each type of LED should preferably be mounted rotationally symmetrically about the optical axis of the objective lens. One embodiment of this is shown in... Figure 7 The image is shown in a top view.

[0048] All LEDs can be controlled individually or in groups. "Can be controlled" means that the LEDs can at least be turned on and off. In some embodiments, the intensity and / or color of the emitted light can also be controlled.

[0049] Figure 6 It shows the method according to the prior art Figure 4 The emission angle of the LED illumination at the endoscope tip. In this case, the emission angle of the LED illumination causes the objective's field of view to be unilluminated or insufficiently illuminated at the edges. This means that the objective's large angle of view is (to some extent) useless. The emission angle represents the range (at the same distance from the LED) where the light intensity is at least 50% of its maximum intensity. Figure 8 It shows the corresponding Figure 6 The radiation patterns shown are all relative to the optical axis of the objective lens. In all the radiation patterns shown, the total illuminance has been normalized to 100%.

[0050] like Figure 9 As shown, you can try installing multiple LEDs of the same type side by side along the radial direction. However, the emission angle will not change as a result (C=A), so a portion of the external field of view will still remain unilluminated. Figure 10 The corresponding radiation pattern is shown, which is consistent with... Figure 8 The radiation patterns shown are indistinguishable in quality. In principle, multiple LEDs are mounted radially, each emitting parallel to the optical axis of the objective lens, which is equivalent to only an enlargement of the emitting surface of a single LED.

[0051] Figure 11 An endoscope tip according to a first embodiment of the present invention is shown. This endoscope tip corresponds exactly to… Figure 4The difference lies in the endoscope tip: the LED does not emit parallel to the optical axis of the objective lens, but rather at a limited angle away from the objective lens. This limited angle can be in the range of, for example, 5°-85°, 5°-80°, 10°-85°, or 10°-80°, preferably in the range of 5°-50°, and more preferably in the range of 10°-45°. This limited angle differs from 0° and 90°.

[0052] For this purpose, the LED is mounted on a surface inclined relative to a surface perpendicular to the optical axis. The inclination angle of this surface corresponds to a change in the emission angle of the lighting device and can be selected according to the required emission characteristics. This surface can be formed, for example, by a frustum, which can be used instead of... Figure 4 The LED has a flat mounting surface. Preferably (but not necessarily), the axis of the truncated cone coincides with the optical axis of the objective lens.

[0053] according to Figure 11 Because the LED is mounted on the surface of the truncated cone, it is also closer to the far end. However, this is not necessary. For example, it can also be... Figure 4 A groove is provided on the LED mounting surface to replace the truncated cone surface, so that the center of the LED emitting surface is aligned with the optical axis. Figure 4 At the same height.

[0054] Figure 12 The cross-sectional view (left) and top view (right) are shown. Figure 11 The components at the tip of the endoscope. This top view corresponds exactly to... Figure 4 A top view of the endoscope tip, only a cross-sectional view of the truncated cone where the LEDs are mounted. Figure 4 The cross-sectional view of the endoscope tip is different.

[0055] and Figure 6 Corresponding to the diagram, Figure 13 It shows Figure 11 The illumination emission angle of the endoscope tip and the aperture angle of the objective lens. It can be seen that the outer area of ​​the endoscope's field of view is now significantly better illuminated. Figure 14 The corresponding radiation pattern is shown. The illumination is still sufficient even when the viewing angle exceeds 180°.

[0056] Figures 15 to 18 A second embodiment of the present invention is shown. Figures 15 to 18 Corresponding to Figures 11 to 14 Unlike the first embodiment, in the second embodiment, the LED is remounted on a plane perpendicular to the optical axis, such as... Figure 4 As shown. However, besides Figure 4In addition to the endoscope tip, the endoscope tip also has an annular mirror mounted around the objective lens. Preferably, this annular mirror is rotationally symmetrical about the optical axis of the objective lens. The reflective surface of this annular mirror faces the LED and is tilted at a limited angle relative to the optical axis. For example, this tilt angle can be in the range of 20°-70° relative to the optical axis. Figure 17 and 18 It can be seen that a portion of the radiation is thus reflected into the outer region of the field of view, where sufficient illumination is also obtained, especially at viewing angles greater than 180°.

[0057] The installation of the circular mirror should ideally avoid creating shadows beyond those cast by the objective lens. This means that the protrusion of the circular mirror should be determined based on its height when installed along the optical axis.

[0058] The ring mirror preferably reflects the emitted light of the LED, which in... Figure 4 The endoscope tip is obscured by the objective lens, thus contributing little or no illumination to the object space. This improves light utilization and reduces energy consumption and heat generation.

[0059] This is Figure 19 and 20 As shown in the image. Figure 19 An endoscope tip (without a transparent cap) according to the prior art is shown, in which a portion of the emitted light from the LED is blocked by the objective lens. Conversely, according to the second embodiment, as... Figure 20 As shown, the blocked light is reflected into the external field of view by the ring mirror. The shadow at the center remains unchanged.

[0060] The mirror surface of a ring mirror can be formed into a truncated cone surface, where no light refraction is applied along the optical axis. However, in some embodiments of the invention, it may be advantageous if the ring mirror applies light refraction along the optical axis, thereby guiding light into certain regions of the field of view. In this case, the mirror surface... Figure 15 , 16 The cross-sectional views of 17 and 20 show a curved shape. The mirror surface of the ring mirror can also typically have any shape. Preferably (but not necessarily), the axis of the truncated cone coincides with the optical axis of the objective lens.

[0061] In some embodiments of the invention, the bottom surface of the ring mirror and at least a portion of the objective lens housing adjacent to the bottom surface of the ring mirror are additionally coated with a reflective coating. Therefore, the emitted light with a flat angle emitted from the LED can be guided into the external field of view through multiple reflections at the objective lens housing and the bottom surface of the ring mirror. This further improves light utilization.

[0062] If the objective lens housing has a protrusion above the LED along the optical axis, for example in Figure 4 and Figure 11In this case, the same effect can be achieved without a ring mirror. According to a third embodiment of the invention, the bottom surface of the protrusion and at least a portion of the objective lens housing adjacent to the protrusion below it are coated with a reflective coating to guide the light from the LED into the external field of view.

[0063] In some embodiments of the present invention, the emission direction of the LED is tilted relative to the optical axis of the objective lens (e.g., Figure 11 As shown), and the circular mirrors are all mounted around the objective lens (as shown). Figure 15 (As shown). Furthermore, as in the third embodiment, a portion of the objective lens housing is also coated with a reflective coating. Therefore, illumination in the external field of view can be further improved.

[0064] As long as the objective lens housing does not have a reflective coating, it can be black and reflect almost no light.

[0065] The reflective surface can be formed by a metallic coating, such as silver. Alternatively, if the space between the cap, objective lens housing, and LED mounting surface is filled with a transparent dielectric, the reflective surface can also be formed by a dielectric with a lower refractive index. Furthermore, in this case, the cap can be the same as the outer layer of the transparent dielectric.

[0066] According to a fourth embodiment of the present invention, an optical refractive element is mounted in the space between the LED and the cap, guiding a portion of the light into the external field of view. For example, the optical refractive element may be located directly outside the light-emitting surface of the LED and extends outward in a wedge shape in cross-section. When the light from the LED is emitted from the wedge-shaped optical refractive element, it is deflected outward toward the external field of view.

[0067] Optical refractive elements that can be connected to LEDs can be arranged to form a frustoconical surface, wherein the axis of the frustocone preferably (but not necessarily) coincides with the optical axis of the objective lens. The optical refractive elements of the fourth embodiment can also be combined with one or more of the first to third embodiments.

[0068] Figure 21 and 22 The general principles according to some embodiments of the present invention are illustrated. They each show a cross-sectional view of the (hypothetical or real) endoscope tip in the plane spanned by the optical axis 11 of the objective lens 1 and the light emission axis of at least one LED 2. The LED 2 emits (hypothetical or real) emitted light 20 symmetrically with respect to the light emission axis.

[0069] Figure 21 It shows the corresponding technology according to the prior art Figure 4The following is a hypothetical reference configuration. In this configuration, LED2 is arranged in a plane perpendicular to the optical axis 11 of objective lens 1. LED2 emits (hypothetical) emitted light 20, which is parallel to the optical axis 11. The (hypothetical) emitted light 20 falls directly onto the transparent cap 6, i.e., it is not deflected by other components such as mirrors or optical refractive elements (lenses). There, it may be deflected and emitted as hypothetical illumination light 60 into the object space (or field of view) of objective lens 1. The hypothetical illumination light is based solely on the emitted light directly emitted by LED2 onto cap 6. The dashed line indicates that this reference configuration is hypothetical.

[0070] Figure 22 The actual configurations according to some embodiments of the present invention are shown for comparison. The actual configurations differ from the reference configurations in that they satisfy one or both of the following conditions:

[0071] • The emitted light 20 is emitted by LED 2, which is not parallel to the optical axis 11; and

[0072] • The (real) illumination light 61 is at least partially based on emitted light that is not directly emitted onto the cap 6 by at least one LED 2, but has been deflected by a reflective or refractive element.

[0073] otherwise, Figure 21 The actual configuration is functionally similar to Figure 22 The configurations are assumed to be the same. In particular, the emission points of the respective light emission axes of LED2 are at the same positions.

[0074] Figure 22 An example of emitting light 20 that is not parallel to the optical axis is shown. Furthermore, the gap between the emitted light 20 and the illumination light 61 indicates that the illumination light contains components other than those emitted directly from the LED 2 onto the cap 6.

[0075] from Figure 22 It can be seen that the real illumination light 61 is guided further away from the optical axis than the hypothetical illumination light 60.

[0076] Arrow 20, representing the emitted light of LED2, indicates the centroid of the angular distribution of the emitted light. Typically, the emitted light is symmetrically emitted around this centroid (e.g., a Lambertian emitter). Arrows 60 and 61, representing (hypothetical or real) illumination light, indicate the centroid of the angular distribution of their respective illumination lights. Typically, due to shading caused by the objective lens, and in the case of real illumination light 61, possibly due to reflection, optical refraction, or optical diffraction components of the illumination light, the angular distribution of the illumination light is not necessarily symmetrical about this arrow.

[0077] LEDs are examples of light-emitting devices according to some embodiments of the present invention. For example, a light guide emitting end may be used instead of an LED. Alternatively, some light-emitting devices may be LEDs, while others may be light guide emitting ends.

[0078] An objective lens is understood as a lens or lens system, and may also include other optical elements that image the scene onto an imaging surface. Specifically, the objective lens images the scene continuously onto the imaging surface. This means that adjacent points in the scene are also adjacent in the image on the imaging surface. The objective lens has a viewing angle greater than 180°. It is preferably greater than 200°, more preferably greater than 220°, and even more preferably greater than 230°. For example, such an objective lens is described in EP19187218.3. Typically, an objective lens is included at the tip of an endoscope.

[0079] Endoscopes can be rigid endoscopes, where the proximal endoscope tip is connected to a rigid tube. Endoscopes can also be flexible endoscopes, where the proximal endoscope tip is connected to a flexible tube. Both rigid and flexible tubes are referred to as "axles." The connection between the endoscope tip and the axis can be achieved directly or indirectly through angular elements. Endoscopes can also be free-floating endoscopes without an axis (capsule endoscopes). Endoscopes (and therefore, of course, endoscope tips) are suitable for insertion into cavities within the human body, such as bronchoscopes, laryngoscopes, or colonoscopes.

Claims

1. An endoscope tip or capsule endoscope, comprising an objective lens for imaging a field of view; as well as An illumination device that illuminates the field of view with illumination light, wherein The objective lens has an optical axis; The objective lens has a field of view greater than 180° and continuously images the scene onto the imaging surface; In a top view along the optical axis, the illumination device is arranged around the objective lens; The lighting device includes a transparent cap from which illumination light is emitted into the field of view; The lighting device includes one or more light-emitting devices configured to emit light from their respective light-emitting surfaces, and the light-emitting devices are arranged in a plane perpendicular to the optical axis. The illumination device includes a reflective surface surrounding the objective lens, and the amount of protrusion of the reflective surface is determined according to the height of the reflective surface in the optical axis direction so as not to create shadows other than those produced by the objective lens. The reflective surface reflects at least a portion of one of the emitted light rays in a direction further away from the optical axis than the direction in which a portion of one of the emitted light rays is incident on the reflective surface, thereby reflecting the portion into the outer region of the field of view.

2. The endoscope tip or capsule endoscope according to claim 1, characterized in that, The lighting device includes a respective reflective surface for each of the light-emitting devices, the reflective surface reflecting at least a portion of the respective emitted light in a direction further away from the optical axis than the direction in which a portion of the respective emitted light is incident on the respective reflective surface.

3. The endoscope tip or capsule endoscope according to claim 2, characterized in that, The lighting device is rotationally symmetrical about the rotation axis.

4. The endoscope tip or capsule endoscope according to claim 3, characterized in that, The lighting device is arranged such that the rotation axis is aligned with the optical axis.

5. The endoscope tip or capsule endoscope according to any one of claims 1 to 3, characterized in that, The respective reflective surfaces are part of a ring mirror, and the ring mirror forms part of a second truncated cone surface.

6. The endoscope tip or capsule endoscope according to claim 5, characterized in that, The axis of the second truncated cone surface is aligned with the optical axis.

7. The endoscope tip or capsule endoscope according to any one of claims 1 to 3, characterized in that, The angular distribution of the illumination light in the plane containing the optical axis includes an angle range greater than 90°.

8. The endoscope tip or capsule endoscope according to any one of claims 1 to 3, characterized in that, Each of the light-emitting devices is a light-emitting diode or the emitter of a light guide.

9. The endoscope tip or capsule endoscope according to any one of claims 1 to 3, characterized in that, The objective lens is located at the distal end of the endoscope tip; the arrangement plane is farther from the distal end of the endoscope tip than the lens apex of the objective lens that is closest to the field of view of the objective lens.

10. The endoscope tip or capsule endoscope according to claim 9, characterized in that, The objective lens housing has a protrusion arranged further away from the light-emitting device in the direction of the optical axis. The bottom surface of the protrusion facing the light-emitting device and at least a portion of the housing adjacent to the bottom surface of the protrusion in the proximal direction are coated with a reflective coating.

11. The endoscope tip or capsule endoscope according to any one of claims 1 to 3, characterized in that, The objective lens is the only objective lens present in the tip of the endoscope.

12. An endoscope, comprising: Endoscope tip according to any one of claims 1 to 11; Its distal end is directly or indirectly connected to the proximal end of the endoscope tip.

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