JPH0443247B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement of a diaphragm device in an endoscope light source device for sending collation light and photographing light to an endoscope light guide.

[Background technology and its problems]

Generally, the light guide of an endoscope uses an optical fiber bundle. What is known about the light conductivity properties of this optical fiber is that light that enters from one end face of the optical fiber at an angle θ with the optical axis becomes a ring-shaped light with a peak of light at approximately the above angle θ from the other end face. This results in a light distribution that emits light. This phenomenon occurs because the light incident on the optical fiber is averaged around the optical axis in the process of being reflected within the optical fiber.

For this reason, a so-called iris diaphragm, which has a complicated mechanism and is expensive, is not normally used in an iris device in an endoscope light source device. That is, normally a single aperture plate 1 as shown in FIGS. 1 and 2 is used.
is used. This diaphragm plate 1 is provided with a notch 2, which allows the light beam to be focused by the condenser lenses 3, 3 to advance and retreat laterally on the optical path of the light beam, thereby adjusting the amount of light that reaches the light guide 4.

However, it has been found that this method has the following problems. That is, especially when the peripheral portion of the luminous flux is slightly passed through, that is, when the amount of illumination light is small, the incident angle is large, and there is a strong tendency for ring-shaped light to be emitted with the light at this incident angle as the peak. In other words, the central part becomes dark and a uniform light distribution cannot be obtained. In particular, as the quality of optical fibers has improved recently, the above-mentioned tendency tends to become more noticeable when the diffused reflection inside the fibers is reduced.

[Purpose of the invention]

The present invention has been made focusing on the above circumstances,
The purpose is to provide a diaphragm device for an endoscope light source device that has a simple configuration, but can improve the light distribution characteristics without making the irradiation light distribution non-uniform even when the light intensity is reduced. be.

[Summary of the invention]

The present invention provides a movable light shielding plate on the optical path between the incident end surface of an optical fiber bundle for illumination of an endoscope and the light source, and the light shielding plate has a zone located on the optical path as the light shielding plate moves. A diaphragm device for an endoscope light source device that improves light distribution characteristics with a simple configuration by distributing a large number of holes for a light amount adjusting diaphragm each having a predetermined aperture ratio that changes with the movement of the diaphragm. .

[Embodiments of the invention]

Examples of the present invention will be shown below.

3 and 4 show a first embodiment of the present invention.

Reference numeral 11 in FIG. 3 is a light source device for an endoscope, and a light source 13 consisting of a high-intensity lamp is provided inside the chassis 12. A condensing lens 14 is installed in front of the light source 13, and condenses the light emitted from the light source 13 and irradiates it onto the incident end surface 16 of the illumination optical fiber bundle 15 on the endoscope side. ing. Incident end 15a of optical fiber bundle 15 for illumination
is adapted to be detachably attached to a socket 17 attached to the chassis 12.

It should be noted that each fiber strand of the illumination optical fiber bundle 15 has a strand diameter of about 100 μm. If the wire diameter is too thick, its flexibility will decrease.
The thickness should preferably be 200μ or less, and if it is too thin, the amount of transmitted light will decrease, so the thickness should be 80μ or more.

A light shielding plate 18 is provided on the output optical path of the light source 13 between the condenser lens 14 and the entrance end surface 16 of the illumination optical fiber bundle 15, and is movable in a direction across the optical path. This light shielding plate 18
As shown in the figure, it is attached to the tip of the rotating arm 19, and is configured to be rotated by a drive section (not shown). Then, the light shielding plate 18
The plate surface portion is divided into a plurality of zones 21a, 21b, 21c, and 21d along the rotational direction, and each zone 21 is divided by the rotation.
a, 21b, 21c, 21d or its zone 2
A portion extending between 1a, 21b, 21c, and 21d is located on the optical path and blocks the light beam. In addition, each zone 21a, 21b,
21c and 21d are shown in Figure 4 A, B, C, respectively.
As shown by D, a large number of through holes 22a..., 22b..., 22c..., 22d... having different aperture ratios are uniformly distributed. Further, the aperture ratio of each zone 21a, 21d, 21c, and 21d is increased from one side to the other. That is, which zone 21a, 21
d, 21c, 21d through holes 22a..., 22b...,
22c..., 22d... are also diagonally arranged at equal intervals (t=0.5mm)
are arranged in Also, the diameter d 1 of the through holes 22a... in the first zone 21a is 0.15 mm, and the diameter d ₁ of the through holes 22a in the first zone 21a is 0.15 mm.
The diameter d ₂ of the through holes 22 b in 1b is 0.21 mm, the diameter d 3 of the through holes 22 c in the _third zone 21 c is 0.3 mm, and the diameter d 4 of the through holes 22 d in the fourth zone ₂₁ d is 0.43.
Each is formed in mm. Therefore, each zone 21d, 21c, 21b, 21a has its through hole 2
By changing the size of 1d..., 21c..., 21b..., 21a, the aperture ratio can be changed to 1/2, 1/4, 1/8...
and changes stepwise along the direction of movement. Furthermore, each zone 21a, 21d, 21c, 2
1d are zones 21b, 21c, and 21c, each having a large aperture ratio, as shown in FIG.
It is formed in a concave shape toward 21d, and in this embodiment, it is formed in an arcuate concave shape. Therefore, when the luminous flux range S is located between the zones 21a, 21b, 21c, and 21d, the zones 21b and 21b have a large aperture ratio,
The convexly protruding portions 21c and 21d come to fit into the center of the luminous flux range S.

By the way, the light-shielding plate 18 is configured to rotate to a required angle to select the aperture position under the control of an exposure control device for endoscopic photography.

When the light shielding plate 18 is rotated according to the aperture amount and the position is selected, the zones 21a, 2
1b, 21c, 21d or across them. At this time, the through holes 22a, 22b, 22c, 22 located in the luminous flux range S
The amount of transmitted light, that is, the aperture value, is determined by the size and number of d. Through holes 22a..., 22b...,
As the larger one of 22c..., 22d... is moved toward the optical path side, the illumination intensity gradually decreases. In addition, each through hole 22a..., 22b..., 22c
..., 22d... are disposed in a dispersed manner in a part of the luminous flux range S, and the light is transmitted through them, so that the light is transmitted over the entire surface. Therefore, each through hole 2
2a..., 22b..., 22c..., 22d... Since there are various incident angles of the light, the light enters the incident end surface 16 of the illumination optical fiber bundle 15 from various directions. The output light distribution of this illumination optical fiber bundle 15 is uniform throughout.

Moreover, as mentioned above, each zone 21a, 21
Since the boundaries between b, 21c, and 21d are concave toward the zones 21b, 21c, and 21d with large aperture ratios, the zones 21b, 21c, and 21d with large aperture ratios are concave.
21c and 21d protrude convexly and are sunk into the center side of the luminous flux range S. Therefore, compared to the case where the boundary line is straight or convex in the opposite direction, the light distribution is less biased, and the light distribution of the illumination optical fiber bundle 15 can be made more uniform.

FIG. 5 shows a second embodiment of the invention. In this embodiment, each zone 21a, 21b, 21
Each through hole 22a..., 22b... in c, 21d,
The aperture ratio is set in the same way as in the above embodiment by making the diameters of 22c, 22d, and so on equal, and instead changing their density.

In the above embodiment, the light shielding plate is divided into a plurality of zones and the aperture ratio is set stepwise for each zone, but the aperture ratio is changed steplessly (continuously) along the direction of movement. Each through hole may be provided in the.

〔Effect of the invention〕

As explained above, the present invention provides a light shielding plate that is movably provided on the output optical path of a light source, and a large number of through holes having a predetermined aperture ratio that differs as the light shielding plate moves, and the light shielding plate is moved. The amount of light can be adjusted by adjusting the amount of light.

Therefore, at each aperture position, the light enters the input end of the illumination optical fiber bundle from various directions without being biased, so that the output light distribution of the illumination optical fiber bundle becomes uniform. In particular, even when the amount of light is reduced, deterioration of the light distribution can be prevented.

Moreover, such improvement in light distribution characteristics can be achieved with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a diaphragm device in a conventional light source device, FIG. 2 is a front view of the diaphragm plate, and FIG. 3 is a schematic configuration of a light source device according to a first embodiment of the present invention. FIG. 4 is a block diagram of the light shielding plate, and FIG. 5 is a block diagram of the light shielding plate in a second embodiment of the present invention. 11... Endoscope light source device, 13... Light source, 1
5... Optical fiber bundle for illumination, 16... Incident end surface, 1
8... Light shielding plate, 21a, 21b, 21c, 21d
...Zone, 22a, 22b, 22c, 22d...
...through hole.

Claims (1)

[Claims] 1. A movable light shielding plate is provided on the optical path between the incident end surface of the illumination optical fiber bundle of the endoscope and the light source, and the light shielding plate has an aperture zone located on the optical path as it moves. A diaphragm device for an endoscope light source device, characterized in that the diaphragm zone is provided with a number of distributed holes each having a predetermined aperture ratio that varies with the movement of the diaphragm zone.