JPH0886967A - Optical filter device - Google Patents

Abstract

PURPOSE: To restrain moire fringe from occurring by providing an optical filter frame capable of attachably/detachably connecting on the output end side of an optical fiber bundle for transmitting an image and a camera provided with a solid-state image pickup element, rotating the optical filter centering the photographic optical axis of the camera with respect to the optical filter frame, and fixing an optical filter on a position where the moire fringe disappears to the optical filter frame. CONSTITUTION: This optical filter device 30 is constituted of the filter frame 42, and a filter holding ring 46 holding an optical low-pass filter 44. The filter 44 is attached to a position whose center axis is aligned with the photographic optical axis 58 of a CCD 34. The ring 46 is rotatably fitted to the circular aperture part 60 of the frame 42. Consequently, the direction of the filter 44 with respect to that of the CCD 34 can be adjusted in the case of rotating the ring 46 with respect to the frame 42. The moire fringe can be restrained by fixing the ring 46 on the position where the moire fringe disappears to the frame 42.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical filter device, and more particularly, to an eyepiece part of an endoscope equipped with an optical fiber bundle as an image guide and a TV camera equipped with a solid-state image pickup device for connecting the optical fiber bundle. The present invention relates to an optical filter device for allowing a TV camera to capture an image appearing at the output end of the.

[0002]

2. Description of the Related Art An endoscope provided with an optical fiber bundle as an image guide has an output end of the optical fiber bundle arranged at an eyepiece portion formed at a hand operation portion of the endoscope and appears at this output end. An image (light image) is observed from the eyepiece portion, or a TV camera having a built-in solid-state image sensor (CCD) is attached to the eyepiece portion to display the light image on a television screen.

When the CCD is used to directly capture the optical image appearing on the optical fiber bundle, moire fringes are generated on the television screen. In this case, an optical filter device having an optical low-pass filter is attached to the endoscope. It is attached between the eye and the TV camera to suppress the generation of moire fringes.

[0004]

Since the optical low-pass filter has a material, a thickness and a cutting angle set in accordance with the CCD of the TV camera, the frequency of the moire fringes must be adjusted unless the direction is aligned with the direction of the CCD. I can't get rid of it. However, when the conventional optical filter is connected to the TV camera, the orientation of the optical low-pass filter is CC.
Since it may not be constant with respect to the direction of D and may deviate, there is a drawback that moire fringes occur.

The present invention has been made in view of such circumstances, and in order to suppress the generation of moire fringes, the direction of the optical filter can be adjusted even after the optical filter frame independent of the adapter body is fixed to the TV camera. An object is to provide an optical filter device.

[0006]

In order to achieve the above object, the present invention provides the adapter between an adapter body on the output end side of an optical fiber bundle for image transmission and a camera equipped with a solid-state image sensor. The main body and removable optical filter frame are provided,
The optical filter frame is provided with an optical filter that removes the frequency of moire fringes of the frequency of the image light appearing at the output end of the optical fiber bundle, and the optical filter rotates around the photographing optical axis of the camera. As described above, the optical filter frame is rotatably supported.

[0007]

According to the present invention, the optical filter is rotated about the photographing optical axis of the camera with respect to the CCD camera, the optical filter frame is positioned on the CCD camera at the position where the moire fringes disappear, and then the optical filter is mounted on the CCD camera. Fix the frame connected to the adapter body. This allows
In the present invention, the generation of moire fringes can be suppressed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of an optical filter device according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a perspective view showing an embodiment in which an optical filter device according to a first embodiment of the present invention is applied to an endoscope. The endoscope 10 shown in FIG.
Has a hand operation section 12, and an output end of an optical fiber bundle 16 which is an image guide is arranged in an eyepiece section 14 formed on the hand operation section 12. An adapter body 15 is connected to the eyepiece portion 14.

The optical fiber bundle 16 is disposed from the eyepiece portion 14 to the distal end hard portion 22 via the endoscope insertion portion 18 and the bending portion 20, and an incident lens (not shown) is provided at its incident end. ing. The objective lens can form an optical image incident from an observation window 24 formed in the distal end hard portion 22 on an incident end of the optical fiber bundle 16, and the formed optical image is an optical image. It is transmitted to the output end of the optical fiber bundle 16 by the fiber bundle 16 and appears as an optical image on the output end face. The optical image appearing on the output end face is split into two directions by a prism (not shown) built in the adapter body 15, one of which is on the eyepiece portion 26 of the adapter body 15 and the other of which is described later on the optical filter device 30. It is guided to the connecting portion 32.

At the connecting portion 32, the optical filter device 3 is provided.
A CCD camera 36 with a built-in CCD 34 is connected via 0, and the optical fiber bundle 16 is placed on the image plane of the CCD 34.
The optical image appearing at the output end of is formed. The optical image formed on the CCD 34 is converted into an electric signal by the CCD 34, and the electric signal is processed into a video signal by the processor 38 and output to the monitor TV 40. As a result, the optical image appearing at the output end of the optical fiber bundle 16 is enlarged and displayed on the monitor TV 40.

As shown in FIG. 2, the optical filter device 30 comprises a filter frame 42 formed in a substantially cylindrical shape, and a filter holding ring 46 holding an optical low-pass filter 44 on its front surface. A female screw 48 is engraved on the inner peripheral portion on the right side of FIG. 2 of the filter frame 42, and this female screw 48 is screwed to a male screw 50 engraved on the connecting portion 32 as shown by a two-dot chain line in FIG. . A male screw 52 is engraved on the outer peripheral portion on the left side in FIG. 2 of the filter frame 42. The male screw 52 is the CCD camera 3 as shown by the chain double-dashed line in FIG.
6 is internally screwed to the female screw 54. This allows the CCD
A filter frame 42 is attached to the camera 36, and is further detachably connected to the endoscope side.

The filter retaining ring 46 is formed in a substantially cylindrical shape as shown in FIGS. The central axis 56 of the optical low-pass filter 44 is the photographing optical axis 5 of the CCD 34.
8 is attached to the front surface of the filter holding ring 46 at a position corresponding to 8. A collar 60 is inserted between the filter frame 42 and the filter holding ring 46, and a set screw 62 is screwed into the collar 60 from the outside of the filter frame 42. Therefore, when the set screw 62 is screwed in, the tip end of the set screw 62 comes into contact with the taper surface 64A on one side of the groove 64 formed in the outer peripheral portion of the collar 60. When the screw 60 is further screwed in this state, the collar 60 is pushed by the set screw 62 and moves leftward in FIG. 3, so that the flange portion 47 formed on the filter retaining ring 46 has an end face of the collar 60 and a step portion of the filter frame 42. It is sandwiched and fixed to 42A. As a result, the filter holding ring 46 can be easily fixed to the filter frame 42, and if the set screw 62 is loosened, the filter holding ring 46 can be fixed.
Since it can be rotated with respect to 2, the orientation of the optical low pass filter 44 can be adjusted.

Further, cutout grooves 66, 66 are formed at symmetrical positions on the front end surface of the filter holding ring 46, and the cutout grooves 6 are formed.
By inserting a jig such as a driver into 6 and 66, the rotation of the filter holding ring 46 is facilitated. According to the optical filter device configured as described above, first, the optical filter device 30 is connected to the CCD camera 36. And
Loosen the set screw 62 and rotate the filter holding ring 46 with respect to the filter frame 42 to adjust the direction of the optical low-pass filter 44 with respect to the CCD 34, so that the moire fringes disappear, that is, the vertical direction of the optical low-pass filter 44. Positioning is performed at a position where the horizontal direction matches the vertical direction and the horizontal direction of the CCD 34. For the alignment work of the vertical direction and the horizontal direction, for example, the indexes indicating the vertical direction and the horizontal direction of the CCD 34 are formed on the CCD camera 36 side, and the indexes indicating the vertical direction and the horizontal direction of the optical low-pass filter 44 are filtered. Retaining ring 4
By forming it in No. 6, the matching work becomes easy.

After the set screw 62 is tightened to fix the filter holding ring 46 to the filter frame 42, the optical filter device 30 is connected to the endoscope side. As a result, the optical filter device according to the present embodiment can suppress the generation of moire fringes. The orientation of the filter holding ring 46 is changed from that of the cutout groove 66 shown in FIG.
If the knurled groove 68 shown in FIG.
It can be easily adjusted with human fingers.

FIG. 5 is a sectional view of an optical filter device according to a second embodiment of the present invention, and the first filter shown in FIGS.
The same or similar members as those in the embodiment are designated by the same reference numerals, and the description thereof will be omitted. In the optical filter device shown in the figure, the optical low-pass filter 44 is attached to the rear side of the filter holding ring 70, that is, to the CCD camera 36 side, and flare prevention is provided on the inner peripheral portion of the filter holding ring 70 in front of the optical low-pass filter 44. The groove 72 is formed.

Further, in this optical filter device, as in the first embodiment shown in FIG.
It is adapted to be fixed to the filter frame 76 by 4. A set screw 78 is screwed into the collar 74 from the outside of the filter frame 76. When the set screw 78 is screwed in, the tip of the set screw 78 is tapered on one side of a groove 80 formed in the outer peripheral portion of the collar 74. Contact the surface 80A. When the screw is further screwed in this state, the collar 74 is pushed by the set screw 78 and moves to the right in FIG. 5, so that the flange portion 71 formed on the filter retaining ring 70 is fixed to the collar 7.
4 and the end portion end surface 76A of the filter frame 76 are sandwiched and fixed. As a result, the filter holding ring 70 can be easily fixed to the filter frame 76, and by loosening the set screw 78, the filter holding ring 70 can be rotated with respect to the filter frame 76. The orientation of the filter 44 can be adjusted.

In the optical filter device of this embodiment, mount screws 48 and 52 are formed in front of and behind the filter frame 42, so that the direction of the optical low-pass filter 44 can be adjusted by screwing it on the TV camera side. An optical fiber bundle having any type of output end can be attached to the mount screw 48 on the front side of the optical axis. That is, if a filter frame is prepared only for the type of TV camera, the characteristics of the optical low-pass filter can be exhibited regardless of the type of the optical fiber bundle, and a good image or photographed image can be obtained. .

Further, the type of optical low-pass filter is TV.
The thickness can be adjusted only by changing the mount length of the filter frame when it varies depending on the type of CCD of the camera, so that no major design change is required. Further, in the case where an optical low-pass filter is provided in the fiberscope eyepiece system or the eyepiece adapter, a complicated component is required as a means for rotationally adjusting the optical lowpass filter, and the number of components is significantly increased. Furthermore, when there are many types of CCDs for TV cameras, the ones with built-in optical low-pass filters are not fully adaptable, and therefore an attachment mechanism and a removal mechanism are required. In the present embodiment, if a filter frame with a small number of parts is prepared according to the type of CCD of the TV camera, there is no need to change the fiberscope eyepiece system or eyepiece adapter, so that the configuration is inexpensive. be able to.

[0019]

As described above, according to the optical filter device of the present invention, the optical filter is rotated with respect to the filter frame about the photographing optical axis of the camera and positioned at the position where the moire fringes disappear. Therefore, the occurrence of moire fringes can be suppressed.

[Brief description of drawings]

FIG. 1 is a perspective view of an endoscope to which an optical filter device according to a first embodiment of the present invention is applied.

FIG. 2 is a perspective view showing an embodiment of the optical filter device shown in FIG.

3 is a sectional view of the optical filter device shown in FIG.

FIG. 4 is a perspective view of an optical filter device in which a knurled groove is formed in a filter retaining ring.

FIG. 5 is a sectional view of an optical filter device according to a second embodiment of the present invention.

[Explanation of symbols]

 10 ... Endoscope 14 ... Eyepiece 16 ... Optical fiber bundle 30 ... Optical filter device 34 ... CCD 36 ... CCD camera 42, 76 ... Filter frame 44 ... Optical low-pass filter 46, 70 ... Filter retaining ring

Claims (1)

[Claims] 1. An optical filter frame detachable from the adapter main body is provided between an adapter main body on the output end side of an optical fiber bundle for image transmission and a camera equipped with a solid-state image sensor, and the optical filter frame is attached to the optical filter frame. Is provided with an optical filter for removing the frequency of moire fringes out of the frequency of the image light appearing at the output end of the optical fiber bundle, and the optical filter is arranged so as to rotate around the photographing optical axis of the camera. An optical filter device, which is rotatably supported by a frame.