JPH01200217A - Power unit for endoscope - Google Patents

Abstract

PURPOSE:To reduce the variation of the spectral characteristics of incident light at the time of varying the light quantity of illuminating light by symmetrically disposing a pair of parallel flat plates which pinch an optical axis between them on an illuminating light path between a condensing lens and a light source and turning the parallel flat plates so that the incident light quantity can be adjusted. CONSTITUTION:In the end part 1 of an endoscope, the image of object is converted into an electrical signal with the illuminating light emitted from the emitting end part 4a of a light guide 4 for illuminating by a solid-state image pickup device 3 so as to be outputted. A pair of parallel flat plates 8 are symmetrically provided in putting the optical axis between them so that it can be turned by a motor 9 on an optical path between the condensing lens 7 which condenses the illuminating light on the incident end part 4b of the light guide 4 for illuminating and the light source 6a. When the parallel flat plates 8 are in parallel with the illuminating light path, the maximum light quantity is incident on the incident end part 4b of the light guide 4 for illuminating. By turning the parallel flat plates 8, the illuminating light path is shut off and luminous flux passing through the middle part of the parallel flat plates 8 is made incident on the condensing lens 7, then the light quantity made incident on the incident end part 4b can be adjusted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a light source device for an endoscope, and in particular, to a light source device for an endoscope, and in particular, a light source device that can adjust the illumination light h) that enters the incident end of the light guide from the light source. This invention relates to a light source device for an endoscope.

[Prior Art] This type of endoscope light source device generally converts illumination light emitted from a light source lamp into a parallel light beam using a reflecting mirror, and focuses the parallel light beam using a condensing lens to form an illumination light guide. The light is incident on the incident end of the .

A movable light shielding plate that partially blocks the illumination light is provided in the middle of the illumination light path from the light source lamp to the incident end of the light guide, and can be moved in and out from the side of the optical path, and the position of the movable light shielding plate is automatically controlled. The amount of illumination was adjusted by doing this.

[Problems to be Solved by the Invention] However, if a movable light shielding plate is inserted into and taken out from the side of the illumination optical path to block the illumination light, as the amount of illumination light is narrowed down, only the illumination light that has passed through the periphery of the illumination optical path is reduced. will be incident on the light guide. Then, since the illumination light is largely refracted in the peripheral area of the lens, the difference in the wavelength of the light causes a deviation in the optical path after refraction, and the spectral characteristics of the illumination light incident on the light guide change. As a result, accurate color reproduction is not performed in the observed image, and there is also a delay in the response speed of the movable light shielding plate, resulting in the drawback that the brightness of the observed screen is not always uniform.

The present invention eliminates such conventional drawbacks and provides a light source device for an endoscope in which when the amount of illumination light incident on the light guide is changed, the change in the spectral characteristics of the incident light is small. With the goal.

[Means for Solving the Problems] In order to achieve the above object, the light source device for an endoscope of the present invention is provided at the incident end of the illumination light guide! 1 (At least a pair of parallel plane plates are arranged symmetrically across the optical axis in the illumination optical path between the condensing lens that condenses bright light and the light source of the illumination light, and the parallel plane plates are perpendicular to the optical axis and A rotating means is provided for integrally rotating the parallel plane plate with a rotation axis in a direction parallel to the face plate, and the amount of light incident on the incident end of the illumination light guide is reduced by blocking the illumination light with the parallel plane plate. It is characterized by being adjustable.

[Function] When the parallel plane plate is parallel to the illumination optical path, the illumination light is not blocked and the maximum amount of light enters the illumination light guide.

When the plane-parallel plates are rotated by the rotation means, the plane-parallel plates interrupt the illumination light path, and the illumination light passes through the intermediate part between the plane-parallel plates (and, in some cases, the illumination light passes through the outside of the plane-parallel plates). ) That is, the light flux extending from the center to the periphery enters the condenser lens and is condensed at the incident end of the illumination light guide.

[Example] Examples will be described with reference to the drawings.

1 is an insertion section of the endoscope, 2 is an objective lens placed at the tip thereof, and a solid-state imaging device 3 made of, for example, a COD (charge-coupled device) is placed at the position where the object is imaged by the objective lens 2.
A light receiving surface is arranged.

Reference numeral 4 denotes an illumination light guide that illuminates the viewing range of the objective lens, 4a is an output end thereof, and 5 is a light distribution lens that expands the light distribution angle of the illumination light emitted from the light guide output end 4a. It is. In this way, the lighting light guide 4
The image of the object illuminated by the image (observation light image) is converted into an electrical signal by the solid-state imaging device 3 and output.

4b is an entrance end of the illumination light guide, 6a and 6b are a light source and a reflecting mirror arranged in the light source device, and the illumination light emitted from the light source 6a is condensed by a condensing lens 7, The light is made to enter the incident end 4b of the illumination light guide.

Further, a pair of parallel plane plates 8.8 are arranged between the light source 6a and the condenser lens 7, and the movement of the parallel plane plates 8.8 is controlled by a motor. 9
controlled by.

Although not shown, in the middle of the illumination optical path,
Color filters of known three primary colors are provided so as to alternate at a rate of about 10 to 30 cycles per second, and time-divided illumination of the three primary colors is performed.

10 outputs a control signal to the solid-state imaging device 3, and
This is a known image signal control circuit that processes the output signal from the solid-state imaging device 3, and a storage device 11 that stores the image signal processed therein and a monitor 12 that reproduces the image are connected in sequence. Further, the brightness signal output terminal of the image signal control circuit 1O is connected to the drive circuit 14 of the motor 9 via the low-pass filter 13. Therefore, the brightness signal of the voltage corresponding to the brightness of the image output from the image signal 8 control circuit 10 is smoothed by the low-pass filter 13, and the motor 9 is driven by the brightness signal. The direction of the parallel plane plate 8.8 is controlled so that the amount of light incident on the solid-state imaging device 3 is constant, but the circuitry of the control system is well known and is not the subject of the present invention. , detailed explanation will be omitted.

The pair of parallel plane plates 8.8 are each formed into a rectangular shape of the same size, and are integrally formed into a U-shape as a whole by a connecting plate 8a that connects them. A rotating shaft 8b is connected and fixed to the center of the bottom of the connecting plate 8a in a direction perpendicular to the illumination optical axis and parallel to the parallel plane plates 8, 8, and the rotating shaft 8b is connected to a motor 9. . Therefore, when the motor 9 rotates, the parallel plane plates 8, 8 rotate about the rotating shaft 8b.

In this embodiment, the parallel plane plates 8, 8 are arranged so that the distance between them is wider than the width of the illumination optical path A, and as shown in FIGS. When is parallel to the illumination optical path A, the illumination light reaches the condenser lens 7 without being blocked at all, and the entire amount of light enters the incident end 4b of the light guide. Then, when the parallel plane plate 8.8 is rotated by the motor 9, as shown in FIGS. 4 and 5, both sides of the optical path are equally blocked by the parallel plane plates 8, 8, and the parallel plane plate Only the light that passes through the intermediate portion that is not blocked by the lenses 8 and 8 enters the condenser lens 7. Therefore, even when the amount of light is reduced, the light from the central part of the illumination optical path A to the peripheral part reaches the condenser lens 7, and the change in spectral characteristics is smaller than in the past.

6 to 8 show a second embodiment of the invention, in which the spacing between the parallel plane plates 28, 28 is narrower than the width of the illumination optical path A.

With this arrangement, when the amount of light is at its maximum, the illumination light is blocked and lost by the thickness of the parallel plane plates 28 and 28, as shown in FIG. As shown in FIGS. 7 and 8, light passing through the central portion B and light passing through both side portions C reach the condenser lens. therefore,
Changes in spectral characteristics are even smaller than in the first embodiment.

9 to 11 show a third embodiment of the present invention,
A slit 3 is provided on the parallel plane plate 38, parallel to the illumination optical axis.
In this embodiment, three slits 38a are cut into each parallel plane plate 38, 38 from opposite sides. Therefore, the parallel plane plate 38
．． When 38 is rotated, as shown in FIG. 11, the illumination light passes through a skewer-shaped cross section in which a slit 38a is added to the middle part between the parallel plane plates 38 and 38. Therefore, in this case, even when the amount of light is reduced, the light that includes the center portion to the peripheral portion of the illumination optical path on average reaches the condenser lens, and the change in the spectral characteristics becomes even smaller.

12 to 14 show a fourth embodiment of the present invention, in which four parallel plane plates 48... are provided. In this case, when the parallel plane plate 48... is rotated,
As shown in FIG. 14, light passing through the center, periphery, and intermediate portions of the illumination optical path reaches the condenser lens 7. Therefore, the change in spectral characteristics is even smaller than in the first embodiment.

In this way, any number of parallel plane plates of the present invention may be provided as long as they are two or more, and may have a shape other than a rectangular shape.

Incidentally, in the second to fourth embodiments described above, the parts other than the parallel plane plate have the same structure as the first embodiment.

[Effects of the Invention] According to the light source device for an endoscope of the present invention, even when the amount of illumination light is narrowed down, the illumination light from the center to the periphery of the illumination optical path enters the condenser lens. There are fewer changes in spectral characteristics compared to other types, so images with stable color tones can always be obtained, and there is no variation in the responsiveness of light amount adjustment, making it possible to always obtain good images with stable brightness. .

Moreover, according to the light source device for an endoscope of the present invention, the entire amount of illumination light can be made incident on the illumination light guide, so there is no loss of light amount when obtaining the maximum amount of light, and the configuration of the device can be adjusted. It has excellent effects such as being extremely simple.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the first embodiment of the present invention, Fig. 2 is a plan view of the illumination optical path of the same embodiment, Fig. 3 is a side view thereof, and Fig. 4 is a parallel plane plate of the same embodiment. A plan view of the illumination optical path in a rotated state, FIG. 5 is a side view thereof, and FIG. 6 is a second embodiment of the present invention.
FIG. 7 is a side view of the illumination optical path of the embodiment, FIG. 7 is a side view of the same embodiment with the parallel plane plate rotated, and FIG. 8 is a plan view thereof.
FIG. 9 is a perspective view of a parallel plane plate according to a third embodiment of the present invention;
FIG. 10 is a side view thereof, FIG. 11 is a side view of the parallel plane plate in a rotated state, FIG. 12 is a perspective view of the parallel plane plate according to the fourth embodiment of the present invention, and FIG. 13 is its side view. Side view, 14th
The figure is a side view of the parallel plane plate in a rotated state. 4...Light guide for illumination, 4b...Incidence end, 6
a... Light source, 6b... Reflecting mirror, 7... Condensing lens, 8°28.38.48... Parallel plane plate, 9... Motor. Agent Patent Attorney Kazuhiko Mitsui Figure 5 Figure 6 Figure 7 Figure 9 Figure 10 Figure 11 Figure 12

Claims (6)

[Claims] (1) In the illumination optical path between the condensing lens that condenses illumination light onto the incident end of the illumination light guide and the light source of the illumination light,
At least a pair of parallel plane plates are arranged symmetrically across the optical axis, and a rotating means is provided for integrally rotating the parallel plane plates with a rotation axis in a direction perpendicular to the optical axis and parallel to the parallel plane plates, A light source device for an endoscope, characterized in that the amount of light incident on the incident end of the illumination light guide is adjusted by blocking illumination light with the parallel plane plate. (2) The light source device for an endoscope according to claim 1, wherein the parallel plane plate is formed in a rectangular shape. (3) The light source device for an endoscope according to claim 1 or 2, wherein the distance between the pair of parallel plane plates is wider than the width of the illumination optical path. (4) The light source device for an endoscope according to claim 1 or 2, wherein the distance between the pair of parallel plane plates is equal to or less than the width of the illumination optical path. (5) The light source device for an endoscope according to claim 1, wherein a slit is formed in the parallel plane plate. (6) Claim 1, wherein a plurality of pairs of the parallel plane plates are provided.
, 2, 3, 4 or 5, the light source device for an endoscope.