JPH02152104A - Adjustment device for light quantity of light source - Google Patents

Abstract

PURPOSE:To make a device compact by forming a plurality of light transmission parts for a light quantity adjustment member in such a way as to be capable of changing an opening area approximately continuously in a direction of the shift of the member, and shifting the aforesaid light quantity adjustment member. CONSTITUTION:A light source lamp 10, a condenser lens 11 and a light guide 12 are provided, and a light quantity adjustment device 13 is provided between the light source lamp 10 and the condenser lens 11. The aforesaid device 13 has a light quantity adjustment strip piece 20 comprising a material such as stainless steel and aluminum free from thermal deterioration and formed into a long thin film strip. The adjustment strip piece 20 is so formed as to have a width larger than the width of a light passage from the light source lamp 10 to the condenser lens 11, and wound about a pair of reels 21 and 22 mounted at both sides of the passage. The rotation of the reels 21 and 22 causes the shift of the adjustment strip piece 20 in a direction orthogonal with the light passage and illumination light from the lamp 10 can be thereby varied from totally close state to totally open state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a light source light intensity adjustment device for adjusting the light intensity of illumination light to an observation target area in a light source device such as an endoscope.

[Prior Art] For example, in an endoscope, an insertion section connected to a main body operation section is inserted into a patient's body, etc., and an image of the observation target area is generated by irradiating illumination light toward the observation target area. can now be observed. An optical endoscope that guides this optical image of the observation target directly to the eyepiece via an image guide, and allows observation with the naked eye by placing the eye in the eyepiece. There is also an electronic endoscope that uses a solid-state imaging device such as a COD to conduct photoelectric conversion, performs predetermined signal processing by a processor, and then displays an image of the area to be observed using a display device such as a cathode ray tube. . As shown in FIG. 7, the illumination optical system of any type of endoscope includes a light source 1 for irradiating illumination light and a collection of illumination light from the light source 1. A condenser lens 2 that emits light; a light guide 3 that transmits the illumination light collected by the condenser lens 2 without attenuating it; It is configured to include an illumination lens 4 for illuminating a predetermined range in .

For example, when observing a position close to the tip of the insertion tube of an endoscope, if the illumination is too strong, it may cause halation, making it difficult to observe well. It is necessary to narrow down the On the other hand, when observing a position away from the distal end of the insertion section, accurate observation becomes difficult unless a certain amount of strong illumination light is irradiated. That is, it is necessary to adjust the amount of illumination light depending on the region to be observed. For this purpose, a light source unit that is provided with a light amount adjustment device for illumination light is conventionally known.

As is clear from FIG. 7, for example, such a light amount adjusting device is such that a light shielding plate 5 is interposed between the light source 1 and the condenser lens 2 (or between the condenser lens 2 and the light guide 3). Some devices are designed to adjust the amount of illumination light from the light source 1 by reciprocating the light shielding plate 5 in a direction perpendicular to the optical axis.

(Problem to be Solved by the Invention l) By the way, in the light source light amount adjustment device using the light shielding plate 5 as described above, from the light guide 3 to the illumination lens 4.
The illumination light emitted through the lamp is not uniform over the entire area, and in particular, as shown by the dotted line in FIG. Since the light-shielding plate 5 is made to enter the optical path from the outer peripheral edge toward the center, the light with the short wavelength * (B) is prevented due to the occurrence of chromatic dispersion in the condenser lens 2 that constitutes the illumination optical system. When performing imaging processing using an imaging means, etc., the color balance of the illumination light is disrupted because the component is subjected to a larger attenuation effect than the long-wavelength red (R) wavelength light component. However, there is a problem in that the color reproducibility in the image deteriorates. Further, the amount of light entering the optical path of the light shielding plate 5 and the amount of light blocking do not change proportionally, and therefore there is a disadvantage that the amount of light cannot be finely adjusted.

Therefore, as shown in FIG. 8, a frame-shaped light beam guide member 6 in which a large number of optical paths 6a having a predetermined length are formed is attached to the rotating shaft 7, and the rotating shaft 7 is rotated. It is also known that the optical path 6a in the light beam guide member 6 is tilted with respect to the optical axis by moving the light guide member 6, thereby reducing the cross-sectional area of the optical path and thereby adjusting the amount of light.

In this way, occurrence of extreme brightness unevenness and deterioration of color balance can be avoided, but when the optical path 6a is tilted, some of the light beam is reflected on the wall surface of the optical path 6a, and the amount of light is adjusted. Since some of the illumination light passes through the device, it is still not possible to strictly uniformize the illumination light. Furthermore, not only is the light flux guide member 6 itself bulky, but it must also be rotated, so a large space must be secured in the optical axis direction in order to install this light amount adjustment device. However, there is a problem in that it is very difficult to install it in a limited space like a light source device for an endoscope.

The present invention has been made in view of the above points, and its purpose is to enable accurate and well-balanced adjustment of the amount of light without requiring a large installation space. An object of the present invention is to provide a light source light amount adjustment device.

Means for Solving Problem E] In order to achieve the above-mentioned object, the present invention makes it possible to move a light amount adjusting member made of a thin film or a thin plate in a direction across the optical path of illumination light emitted from an illumination light source. The light amount adjusting member is provided with a plurality of light transmitting portions whose opening area changes almost continuously in the direction of movement of the light amount adjusting member, and by moving the light amount adjusting member, the illumination light from the illumination light source is Its feature is that it is configured to change the optical path cross-sectional area.

[Function] By configuring as described above, when the light amount adjusting member is moved, the opening area of the light transmitting portion facing the optical path changes, so that the amount of illumination light can be adjusted.

Since this light ψ adjusting member is made of a thin film or a thin plate, its structure can be made extremely compact, and it can be placed even in an extremely narrow part of the optical path from the illumination light source.

The light amount adjusting member is formed into a long belt shape and is wound around a pair of reels provided on both sides of the optical path. By rotating it, the cross-sectional area of the optical path can be changed continuously from a fully closed state to an almost fully open state, and a light transmitting part is provided on the outer periphery of the annular member to adjust the amount of light. When performing this, the disk may be rotated in an appropriate direction, and whichever of these configurations is adopted, the structure can be simple and compact.

Furthermore, since a plurality of light transmitting parts formed in the light amount adjusting member are provided in a direction perpendicular to the moving direction of the light amount adjusting member, the light path can be narrowed down almost uniformly over the entire illumination optical path. This makes it possible to prevent uneven illumination and loss of color balance of illumination light. The light transmitting portion formed in the light amount adjusting member may include a plurality of rows of slits whose width changes in the direction of movement of the light amount adjusting member, or a light transmitting portion whose area increases in the direction of movement of the light amount adjusting member. Gradually changing rectangular, diamond-shaped, circular, etc. openings may be provided in multiple rows or randomly, and in these light transmitting portions, the opening area may be larger in the peripheral rows than in the central portion. By doing so, it becomes possible to correct a decrease in color balance due to aberrations in an illumination optical system equipped with a condenser lens, and to produce illumination light that can reproduce colors more faithfully.

[Embodiment 1] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

First, FIG. 1 is a diagram schematically explaining the principle of the light amount adjustment device according to the present invention. The device 13 is interposed between the light source lamp 10 and the condenser lens 11.

The light amount adjustment device 13 has a light amount adjustment strip 20 formed of a material that does not cause thermal deterioration, such as stainless steel or aluminum, in the shape of a long thin film strip, as a light i:JJ adjusting member.
The light amount adjusting strip 20 is formed wider than the width of the optical path from the light source lamp 10 to the condenser lens 11, and is wound around a pair of reels 21 and 22 attached to both sides of the optical path. By rotating these reels 21 and 22 in the same direction, the light amount adjustment strip 20 is moved in a direction perpendicular to the optical path, and the illumination light from the light source lamp IO is changed from a fully closed state to an almost fully open state. It is now possible to change.

Therefore, in order to rotate the reels 21 and 22 simultaneously in the same direction, both reels 2+ and 22 are rotated as shown in FIG.
The rotating shafts 2+a and 22a each have a pulley 23.
24 is attached, one pulley 23 is connected to a forward/reverse motor 25, and the motor 25 moves the reel 21.
It is designed to be driven in rotation. Also, this pulley 23
A transmission belt 2B for transmitting rotation to the reel 22 is wound between the pulley 24 and the reel 22. Therefore, when the motor 25 is actuated, the optical axis adjustment strip 20 is moved so as to be wound onto either the reel 21 or 22.

As shown in FIG. 3(a), the light amount adjusting strip 20 is formed with a slit-shaped opening, so that the light transmitting portion 27
A plurality of rows (three rows in the drawing) are formed. The light-shielding portion of the light amount adjusting strip 20 is formed with an anti-reflection IF film having good light absorption properties. Therefore, the light passing through the light amount adjustment strip 20 becomes horizontally striped, as shown by diagonal lines in FIG. You will be able to narrow it down to Moreover, the width of this light transmitting portion 27 becomes continuously wider in the direction shown by the arrow in the figure.
Accordingly, when the light amount adjusting strip 20 is moved in a direction perpendicular to the optical path, the width of the light transmitting portion 27 facing the optical path changes, and the amount of light changes.

Therefore, by attaching the light amount adjusting strip 20 so as to wrap it around the reel 21, 22, and rotating the reel 2+, 22 by driving the motor 25 as appropriate depending on the position of the observation target, etc. When the light amount adjustment strip 20 is moved in a direction perpendicular to the optical path, the cross-sectional area of the optical path formed by the light transmitting section 27 having an opening area that changes in the relevant direction changes, resulting in a fully closed state that completely blocks illumination light. The amount of light yA is continuously increased from
You will be able to make adjustments.

Since the light amount adjusting device 13 restricts the optical path to form a plurality of horizontal stripes, the entire optical path can be adjusted evenly. Moreover, since the light transmitting portion 27 is designed to change continuously in the length direction of the light amount adjustment strip 20, it is possible to change it continuously following the movement of the light amount adjustment strip 20. This makes it possible to finely adjust the amount of light.

By the way, the illumination light from the light source lamp IO is adjusted by the light amount adjusting device 13. When irradiating through the condenser lens 11 and light guide 12, the distribution of the luminous flux changes due to the light amount adjustment strip 20 in the light amount adjustment device 13, so that due to the influence of aberrations of the condenser lens 11, R, G, The light intensity balance of each wavelength light of H may be disrupted, and this can be corrected by COD.
If images are captured in a frame-sequential manner using an image sensor such as , and displayed as they are on a display device, the reproducibility of equal colors may be poor, with the entire image taking on a reddish tinge.

Therefore, in order to prevent such color balance from worsening, as shown in FIG. 4(a), the light amount adjusting strip 30
The light transmitting parts 32, 32 on both sides are formed to have a wider width than the light transmitting parts 31, 31 in the central part. As a result, as shown by diagonal lines in FIG. 4(b), the amount of light in the peripheral portion can be made greater than the amount of light in the center, and color balance can be improved.

Furthermore, as shown in FIG.
It is also possible to make the opening area larger in the direction of the arrow in the figure. With this configuration, the illumination light passing through the light Flr, 'r14 adjustment device can be made into a checkerboard pattern, so that more uniform illumination can be achieved. Note that this light transmitting portion can be formed not only in a rectangular shape but also in a rhombic shape and a circular shape.

Furthermore, as shown in FIG. 6, a disc-shaped light amount adjustment member 50 is used, and the light amount adjustment member 50 has a plurality of rectangular light transmitting portions 51 similar to those shown in FIG. 5 in the rotation direction. The light transmitting portions 51 of each row may be formed so as to become larger in the direction of rotation, or a large number of slit grooves may be provided in the radial direction, and the groove width of each slit groove may be set so as to face the direction of rotation. It is also possible to change the optical path cross-sectional area of the illumination light by sequentially increasing the size of the illumination light, and by connecting the light amount adjusting member 50 to a rotation drive means such as a motor and rotating it.

In each of the embodiments described above, the light amount adjusting device is arranged between the light source lamp 10 and the condenser lens 11, but the light amount adjusting device is arranged between the condenser lens 11 and the light guide 12. Alternatively, the illumination light from the light source lamp 10 may be parallelized using a collimating lens or the like, and the amount of illumination light can be adjusted by passing it through this light amount adjustment device. It may be adjusted.

[Advantageous Effects of the Invention 1] As explained above, the present invention allows illumination light to be adjusted by using a light amount adjusting member that is made of a thin film or a thin plate and has a plurality of light transmitting portions whose opening area changes almost continuously in the direction of movement of the light amount adjusting member. The optical path cross-sectional area of the illumination light is changed by moving the light amount adjusting member, which is installed in a direction perpendicular to the optical path, so the structure is simple and the overall configuration of the device can be made extremely compact. The amount of light can be adjusted finely and uniformly over the entire optical path.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, in which FIG. 1 is a diagram explaining the principle of a light amount adjustment device, FIG. 2 is a diagram explaining the configuration of the light amount adjustment device, and FIG. (a) is an explanatory diagram of the configuration of the light amount adjustment strip, FIG. 3(b) is an explanatory diagram of the operation of the light amount adjustment device, and FIG. 4(a) is a configuration diagram of the light amount adjustment device showing the second embodiment of the present invention. FIG. 4(b) is an explanatory diagram of its operation. FIG. 5 is an explanatory diagram of the configuration of a light amount adjusting device showing a third embodiment of the present invention. FIG. 6 is a diagram of a fourth embodiment of the present invention. FIG. 7 is a diagram illustrating the principle of a light quantity adjustment device according to the prior art, and FIG. 8 is a diagram illustrating the principle of another prior art. 10: light source lamp, 11: condenser lens, 12 light guide, 13: light amount adjustment device, 20, 30, 40° 50: light amount adjustment strip, 27, 31, 32, 41
, 51: Light transmitting part.

Claims (1)

[Claims] A light amount adjustment member made of a thin film or a thin plate is provided so as to be movable in a direction crossing the optical path of illumination light from an illumination light source, and the light amount adjustment member has a plurality of openings whose opening areas change almost continuously in the direction of movement. A light source light amount adjusting device, characterized in that the light transmitting portion is formed, and the optical path cross-sectional area of the illumination light from the illumination light source is changed by moving the light amount adjusting member.