JPS61177420A - Light source device for endoscope - Google Patents

Abstract

PURPOSE:To prevent the change of the luminous intensity distribution characteristic and the spectral characteristic by providing a control means of the quantity of light, a fiber bundle where fibers having a certain numerical aperture are bundled, and an oscillating means on an optical path. CONSTITUTION:Mode of light transmitted by a fiber bundle 6 are multiplexed and uniformed by oscillation to control the exit angle in the exit end of the bundle 6 to an about certain aperture angle. If the bundle 6 is not oscillated by an oscillator 7, the intensity distribution of the light in the exit end of the bundle is as shown by a dotted line in the figure with respect to the exit angle when the light condensed by a lens 3 is narrowed by a stop 4 and is irradiated to the incidence end of the bundle 6; but is the bundle 6 is oscillated, transmission modes are multiplexed and uniformed and the intensity distribution which is hardly dependent upon the extent of aperture is obtained as shown by a solid line in the figure. As the result, the luminous intensity distribution characteristic and the spectral characteristic of the light incident on the end surface of a light guide 8 are not changed by the extent of aperture.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a light source device for an endoscope in which light distribution characteristics etc. do not change even when the irradiation amount is varied.

[Technical Background of the Invention and Problems Therewith] In recent years, endoscopes that use solid-state image sensors to display images of objects on display devices such as cathode ray tubes have been realized.

Electronic endoscopes that use the solid-state imaging devices described above are easier to record images than those that form optical images on image guide fibers, and will continue to increase in the future as highly integrated technology progresses. It has the advantage that it can be made smaller.

However, when using the above-mentioned solid-state image sensor, if the amount of light incident on the light receiving element on the mBJ surface is too large, excessive charge leaks to the surrounding area, causing blurring and blooming phenomenon on the reproduced screen, and that part becomes an image. There is a problem that it becomes impossible to faithfully reproduce the image, and that the image cannot be transferred until the normal state is restored.

A conventional example of a diaphragm device for controlling the intensity of illumination light on the light source device side so as to prevent the blooming phenomenon described above is shown in FIG. 5.

That is, the light from the discharge lamp 51 as a light source is reflected by a concave reflecting mirror 52 to form a substantially parallel light beam, and this parallel light beam is sent to the input end of a light guide fiber 54 as an illumination light transmission means by a condenser lens 53. In the optical system for irradiation, as shown in FIG. 6, the center of the disk is cut out on the optical path between the condenser lens 53 and the light guide fiber 54, and a part of the disk is cut out in a substantially fan shape. By moving the aperture 55 in parallel or rotationally (downward in FIG. 6), a part of the light beam is blocked depending on the movement of the aperture 55, and the light guide fiber 54 is The amount of illumination light emitted from the other end of the light guide fiber 54 to the subject side is adjusted.

However, in this conventional example, when the aperture 55 is used to narrow down the light beam, the light beam is blocked from the periphery, so the orientation angle distribution of the illumination light emitted from the tip surface of the light guide fiber 54 toward the subject (object) side As a result, the light distribution characteristics change, and the illumination intensity of each part within the field of view changes non-uniformly. Furthermore, this shape has the disadvantage that the response speed of the aperture operation is slow, making it unsuitable for automatic light control.

Further, in the light guide fiber 54, the maximum incident angle at which light can be transmitted normally depends on the wavelength, that is, the numerical aperture varies depending on the wavelength. For this reason, when the condensed light is irradiated onto the input end of the light guide fiber 54 as in the conventional example, if the aperture 55 is used to narrow the optical path in the middle of the condensed light, the light is blocked from the peripheral part side where the wavelength dependence is large. Therefore, there was a drawback that the spectral characteristics of the illumination light irradiated from the output end side of the light guide fiber 54 to the subject side also changed (depending on the aperture amount).

Further, even if the aperture 55 is disposed in the parallel beam portion, there is a drawback that the light distribution characteristics change.

[Object of the Invention] The present invention has been made in view of the above points, and it is possible to prevent the light distribution characteristics and spectral characteristics from changing even when the amount of illumination light emitted to the subject side is changed by changing the aperture. The purpose of the present invention is to provide a light source device for an endoscope.

[Summary of the Invention] The present invention provides a means for adjusting the amount of light, a fiber bundle made of fibers having a fixed numerical aperture, and an excitation means for vibrating the same, in the optical path between the light source and the incident end of the light guide. By providing this, the transmission mode of the light transmitted through the fiber is multiplexed and uniformed by the excitation means, and the numerical aperture of the light emitted from the fiber bundle output end can be kept constant regardless of the numerical aperture of the incident light. In this way, even if the amount of illumination light is varied, the light distribution characteristics and spectral characteristics are kept constant.

[Embodiments of the invention] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 shows a first embodiment of a light source device for an endoscope according to the present invention.

As shown in this figure, the illumination light from the light source 1 is transmitted to the concave surface 112.
This parallel light flux is condensed by a condenser lens 3, and the amount of illumination light is adjusted by a diaphragm 4 on the optical path. The beam is irradiated onto the incident end face).

The mode scrambling device 5 is composed of a fiber bundle 6 and its vibrator (exciter) 7. The other end (output end) of the fiber bundle 6 is arranged opposite to the input end of the light guide 8. The light guide 8 is located at the endoscope insertion section (
(not shown), and the object is irradiated from the emission end on the distal end side.

The fiber bundle 6 is formed into a shape in which a large number of fibers having a certain numerical aperture are bundled together and not bent, and the part of the fiber bundle 6 that is bent is arranged so that it can be imaged, for example, in the vertical direction by a vibrator 7. . Due to this vibration, the modes of light transmitted by each fiber of the fiber bundle 6 are multiplexed and homogenized, and the output angle at the output end of the bundle 6 remains approximately constant regardless of the aperture angle incident on the Q4 end of the bundle 6. It is designed to form the corner of the mouth.

In such a configuration, for example, when the fiber bundle 6 is not vibrated by the vibrator 7, the light condensed by the lens 3 is narrowed by the aperture 4 and irradiated onto the input end of the fiber bundle 6. , assuming that the intensity distribution of the light at the bundle output O4 end is the distribution shown by the dotted line in Figure 2 with respect to the emission angle, when the vibration is excited by the exciter 7, the transmission mode is as shown by the solid line in the figure. is multi-uniformed, resulting in an intensity distribution that is almost independent of the aperture. As a result, the light distribution characteristics and spectral characteristics of the light incident on the end face of the light guide 8 can be prevented from changing depending on the aperture amount.

FIG. 3 shows a second embodiment of the invention. In this embodiment, the input end of the fiber bundle 6 shown in FIG. 1 is tilted to make it possible to adjust the amount of fiber input into the bundle 6. In this figure, numeral 1 is a light source, 2 is a concave mirror,
3 is a condenser lens, and the condensed light is turned into parallel light by a concave lens 9 and is irradiated to the input end of the mode scrambling device 5A. The mode scrambling device 5A includes a fiber bundle 6 and an exciter 7 that vibrates it.
It is configured such that the incident end can be tilted at an arbitrary angle by the rotary drive device 10. The output end of the bundle 6 is arranged opposite to the input end of the light guide 8.

In this embodiment, a parallel light beam from a concave lens 9 is guided to the input end of the fiber bundle 6 constituting the mode scrambling device 5A, and when the rotation drive device 10 is not rotated in this parallel light beam, the rotation drive device 10 is not rotated. As shown in Figure 4, the input end face of the fiber bundle 6 is perpendicular to the parallel light.If the input end of the fiber bundle 6 is tilted from this state by the rotary drive device 9, it will become as shown in Figure 4 (b). ), the parallel light is obliquely incident on the incident end face of the bundle 6, and the amount of incident light can be changed in the direction of decreasing.In the case of oblique incidence, the fiber bundle 6 remains unexcited. If the light beam is emitted from the output end of the bundle 6 at The uniform illumination light emitted from the output end of the bundle 6 is converted into uniformly oriented light.

Note that the above embodiment describes a case where the light distribution and spectral properties are made uniform when changing the aperture m in a light source device used in an endoscope. It can also be applied to such cases.

[Effects of the Invention] As described above, according to the present invention, even if the amount of illumination light is changed, the light distribution characteristics and spectral characteristics of the light irradiated onto the light guide can be kept constant.

Moreover, it can be realized simply by exciting the fiber bundle using an exciter, and the structure is simple and cost-effective, and the light utilization efficiency is also good.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the light source device for an endoscope according to the present invention, FIG. 2 is a light intensity distribution diagram for explaining the operation of FIG. 1, and FIG. A configuration diagram showing the second embodiment, FIG. 4 is an explanatory diagram of the operation of FIG. 3, FIG. FIG. 3 is a schematic front view of the diaphragm shown in FIG. 1...Light source 4...Aperture 5.5A・
...Mode scrambling device 6...Fiber bundle 7...Exciter 8...Light guide 1o...
...Rotary drive device agent Patent attorney Susumu Ito Figure 1 Figure 2 Figure 0 Book 1: The dermis Figure 3 Figure 4 (0) (b) Continued from page 1 ■Int, CI,' Identification symbol Agency Serial number G O2B 26702
B-7036-2H) Inventor Nakamura -
Husband Hatagaya 2, Shibuya-ku, Tokyo Inventor Ken Sugawara Hatagaya 2, Shibuya, Tokyo Inventor Hideo Tomabechi 2 Hatagaya, Shibuya, Tokyo
Inside the corporation

Claims (3)

[Claims] (1) In an endoscope light source device that guides illumination light from a light source to a light guide in an endoscope insertion section and illuminates an object through this light guide, the light source and the incident end of the light guide are connected to each other. On the optical path, a light amount adjusting means that can adjust the amount of illumination light from the light source, and a fiber bundle formed by bundling fibers having a constant numerical aperture and guiding the light whose amount has been adjusted to the light guide. and a vibrating means for vibrating the fiber bundle to multiplex and homogenize transmission modes of light transmitted through each fiber. (2) The light amount adjusting means is constituted by a diaphragm device that is disposed on the optical path and adjusts the light amount by blocking a part of the illumination light. Light source device for endoscopes. (3) The light amount adjusting means is comprised of a bundle tilting means that is disposed at the input end of the fiber bundle and adjusts the amount of light incident on the bundle by tilting the input end at an arbitrary angle. A light source device for an endoscope according to claim 1.