JP3397444B2 - Endoscope light source device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for an endoscope, and more particularly, to a light beam (illumination light) (illumination light) incident from a light source on an incident end of a light guide of the endoscope. Brightness) can be adjusted. 2. Description of the Related Art Generally, an endoscope light source device of this kind is
Illumination light emitted from the light source lamp is converted into a parallel light beam by a reflecting mirror, and the parallel light beam is focused by a condenser lens to be incident on an incident end of an illumination light guide. [0003] A movable aperture is provided in the middle of the illumination light path from the light source lamp to the light guide entrance end so as to block the illumination light path from the outer edge, so that the luminous flux (brightness) of the illumination light entering the light guide is reduced. Adjustments were being made. However, in such a light source device, the passage of the illumination light incident on the light guide changes with the adjustment of the incident light flux, and the light distribution characteristics and spectral characteristics of the illumination light emitted from the light guide change significantly. There is a problem. In order to solve such a problem, a light-shielding plate composed of at least one pair of parallel flat plates is disposed symmetrically with respect to the optical axis between the condenser lens and the light source, and the light-shielding plate is perpendicular to the optical axis. In addition, by changing the direction of the light shielding plate with the direction parallel to the light shielding plate as the rotation axis, the luminous flux of the illumination light incident on the light guide is adjusted (Japanese Patent Laid-Open No. 1-220017).
issue). With such a configuration, it is possible to reduce a change in the light distribution characteristics and the spectral characteristics of the illumination light emitted from the light guide with a simple structure. As a light source lamp for illuminating an endoscope, a xenon lamp that is bright and generates a small amount of heat is widely used. However, the light emitted from the xenon lamp may flicker at the center due to discharge between the electrodes or convection of the xenon gas. [0007] Such flicker is not so noticeable when viewed from the entire illumination light. However, if a portion other than the central portion of the illumination light path is blocked, the ratio of the center light to the peripheral light increases, so that the flicker is noticeable. Initially, it will hinder endoscopic observation. Accordingly, the present invention provides an endoscope light source device in which flickering is not noticeable even if an illumination light path is blocked in order to adjust a light flux amount (brightness) of illumination light incident on a light guide of the endoscope. The purpose is to do. In order to achieve the above object, a light source device for an endoscope according to the present invention comprises a light collecting device for collecting illumination light at an incident end of an illumination light guide. At least a pair of light shielding plates are arranged in parallel on the illumination optical path between the lens and the light source of the illumination light with the optical axis interposed therebetween, and the light shielding plates can be rotated about a rotation axis perpendicular to the optical axis. In the light source device of the endoscope, wherein the light shielding device blocks the illumination light to adjust the light flux of the illumination light incident on the incident end of the illumination light guide, the rotation of the light shielding plate A central light-shielding plate is provided, which gradually blocks the central portion of the illumination light path as the illumination light path is gradually blocked. An embodiment will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes an insertion portion of an endoscope, and 2 denotes an objective lens disposed at a distal end thereof, and a light receiving surface of a solid-state imaging device 3 is disposed at a position where an image of a subject is formed by the objective lens 2. However, an image guide fiber bundle may be used instead of the solid-state imaging device. Reference numeral 4 denotes an illumination light guide fiber bundle for illuminating the field of view of the objective lens 2, and an observation portion is illuminated by illumination light emitted from the emission end 4a. 10 is a light guide fiber bundle 4
A light source device for supplying illumination light to the light guide fiber bundle, in which an incident end 4b of a light guide fiber bundle 4 is detachably inserted. Light source lamp 1 arranged in light source device 10
The illumination light emitted from 1 as a parallel light beam is condensed by the condenser lens 12 and is incident on the incident end 4 b of the light guide fiber bundle 4. A xenon lamp is used as the light source lamp 11. In an illumination light path between the light source lamp 11 and the condenser lens 12, an illumination light path 50 reaching the condenser lens 12 is provided.
A pair of light-shielding plates 13, 13 composed of a pair of opaque thin parallel flat plates are arranged so as to block a part or the whole of the light-shielding plate. The pair of light shielding plates 13, 13 are formed in a rectangular shape of the same size, and are integrally formed in a U-shape as a whole by a connecting plate 14 for connecting them. At the center of the bottom of the connecting plate 14, the rotating shaft 1 is arranged in a direction perpendicular to the illumination optical axis and parallel to the light shielding plates 13, 13.
5 is connected and fixed. By rotating the rotating shaft 15 by a motor or manually, the direction of the light shielding plates 13, 13 can be changed and can be stopped at an arbitrary position, whereby the illumination light incident on the light guide fiber bundle 4 can be changed. The luminous flux (brightness) can be changed. At the front end side of the light shielding plates 13, 13, central light shielding plates 16, 16 made of the same thin metal plate as the light shielding plates 13, are provided at both ends of the U-shaped light shielding plates 13, 13. It is disposed obliquely inward from the portion, and only that portion has a U-shaped opening formed in an M shape. FIGS. 2 to 5 show such a light shielding plate 13.
FIG. 2 shows a state in which the illumination light path 50 in which the light shielding plates 16 and 16 are integrally arranged is viewed from the front. FIG. In this state, both the light shielding plates 13 and 16 do not block the illumination light path 50. When the rotary shaft 15 is gradually rotated from the state shown in FIG. 2, the right and left halves of the illumination optical path 50 are equally distributed by the light shielding plates 13 and 13, as shown in FIGS. , Is gradually blocked by a large area. In this case, the light at the peripheral portions on the left and right sides of the illumination light path 50 and the light at the vertical portion at the center are separated by the light shielding plates 13 and 13.
Since the light enters the light guide fiber bundle 4 without being blocked by the light guide, the change in the spectral characteristics of the light incident on the light guide fiber bundle 4 is small. As shown in FIGS. 3 to 5, the central portion of the illumination optical path 50 is gradually and widely blocked by the central light shielding plates 16, 16. As shown in FIG. Therefore, even when the amount of illumination light flux incident on the light guide fiber bundle 4 is reduced, the ratio of the light in the central portion of the illumination light path 50 to the incident light flux does not increase, so that the flicker of illumination is inconspicuous. The width and length of the central light-shielding plates 16, 16 and the mounting position with respect to the light-shielding plates 13, 13 may be appropriately selected depending on design conditions and the like. It may be provided at any position of the plates 13, 13. As shown in FIG. 6, the central light shielding plates 16, 16 may be formed obliquely inwardly between the light shielding plates 13, 13 from the connecting plate 14 side. The number of the light shielding plates 13 need not be one, but may be three or more. The specific structure of the present invention may take various other forms. According to the present invention, the light-shielding operation of the light-shielding plate, which interrupts the illumination light path incident on the light guide of the endoscope,
Since the central light-shielding plate blocks the central part of the illumination light path, flickering of the illumination light entering the light guide is not noticeable even when the light-shielding area is widened, resulting in an easy-to-view endoscopic image and accurate diagnosis. And treatment can be performed. In addition, according to the present invention, this can be performed extremely easily with a simple configuration that merely changes the shape of the light shielding plate.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view schematically showing an overall configuration of a first embodiment of the present invention. FIG. 2 is a front view showing the operation of the first embodiment of the present invention. FIG. 3 is a front view showing the operation of the first embodiment of the present invention. FIG. 4 is a front view showing the operation of the first embodiment of the present invention. FIG. 5 is a front view showing the operation of the first embodiment of the present invention. FIG. 6 is a perspective view of a light shielding plate according to a second embodiment of the present invention. [Description of Signs] 4 Light guide fiber bundle 4b Incident end 11 Light source lamp 12 Condensing lens 13 Light shield 15 Rotation axis 16 Central light shield 50 Illumination optical path

Continued on the front page (72) Tadashi Takahashi 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Optical Industry Co., Ltd. (72) Inventor Ryoji Honda 2-36-9 Maeno-cho, Itabashi-ku, Tokyo Asahi Optical (56) References JP-A-1-200217 (JP, A) JP-A-1-223930 (JP, A) JP-A-63-182621 (JP, A) JP-A-2-58720 (JP) , U) (58) Field surveyed (Int. Cl. ⁷ , DB name) A61B 1/00-1/32

Claims (1)

(57) [Claim 1] An optical axis is provided in an illumination optical path between a condenser lens for condensing illumination light at an incident end of an illumination light guide and a light source of the illumination light. At least a pair of light shielding plates are arranged in parallel with the light interposed therebetween, the light shielding plate is configured to be rotatable about a rotation axis perpendicular to the optical axis, and the illumination light is blocked by the light shielding plate. In the light source device of the endoscope, which adjusts the light flux of the illumination light incident on the incident end of the guide, the center of the illumination light path is associated with the illumination light path being gradually blocked by the rotation of the light shielding plate. Place the central light-shielding plate that gradually blocks the part from each of the pair of light-shielding plates above the middle
A light source device for an endoscope, wherein the light source device is disposed obliquely around the optical axis .