JPH048765B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image photographing illumination device used when photographing in a frame sequential manner in an endoscope or the like which photographs and observes color images using a solid-state image sensor.

[Conventional technology]

In recent years, it has become possible to take color images by installing a solid-state imaging device such as a CCD at the tip of an endoscope, and to perform diagnosis by recording this color image as a still image on a magnetic disk or displaying it on a monitor device. It is being said. By the way, in this case, a solid-state image sensor such as a CCD is installed in an extremely narrow space at the tip of the endoscope, and therefore cannot have a large number of pixels.
For this reason, color imaging is performed using a frame sequential method that effectively uses all pixels. In this field sequential method, as shown in Japanese Patent Application Laid-Open No. 59-151591, a turret equipped with a filter that separates and passes three colors of red, green, and blue is rotated on the illumination side, and each color is illuminated. A component image of each color is obtained by separating it into light and sequentially illuminating it, and the 3 images for each pixel are
A color image signal is generated by combining color component signals.

[Problem that the invention seeks to solve]

In the case of the above method, the light emitted from the lamp light source passes through red, green, and blue filters, is focused by the optical system, and enters the light guide of the endoscope. Detection is performed during a blanking period between the transmission times of each light, that is, when no light is incident.

For this reason, unless the blocking of the incident light is clear,
Since the image detection of each color becomes inaccurate, the blanking period is long.

Therefore, since the blanking period becomes longer, the effective amount of transmitted light for each color decreases, resulting in a problem that the illumination becomes darker.

[Means for solving problems]

The present invention provides a turret with filters of each color that are sequentially positioned by rotation on the optical path emitted from the illumination light source, and furthermore, when the transmission apertures of the filters of each color are positioned on the optical path emitted from the illumination light source, at least This is an illumination device for photographing a color image, which is provided with a diaphragm having a transmission aperture whose shapes match the entry start end and the end end.

[Effect]

Even if the cross-sectional shape of the light beam emitted from the illumination light source remains circular, the blanking period is shortened by blocking the protruding portion that does not match the shape of the filter opening with the diaphragm.

〔Example〕

FIG. 1 shows a first embodiment of the invention. Reference numeral 1 in FIG. 1 indicates a lamp as a light source for illumination. The light beam emitted from the lamp 1 is converted into a light beam parallel to the central axis of the output optical path L by the lens group 2 at the front stage. Further, the light beam parallel to the central axis of the output optical path L is focused by the lens group 3 at the rear stage, and is made to be incident on the entrance end surface 5 of the light guide 4 of the endoscope.

Further, in the output optical path L, a peripheral portion of a turret 6 is inserted between the front and rear lens groups 2 and 3. As shown in FIG. 2, around the turret 6, filters 7, 8, and 9 of each color of red (R), green (G), and blue (B) are provided discontinuously and concentrically. ing. The discontinuous portion between the filters 7, 8, and 9 of each color is the illumination light, that is, the solid-state image sensor, for reading out signals from the TL type solid-state image sensor of the device that sequentially captures component images of each color in a frame-sequential manner. Acts as a shutter to block light from entering the area. Incidentally, lead detection portions (not shown) are provided around the turret 6 in correspondence with the installation positions of the filters 7, 8, and 9 of each color. Further, this turret 6 is driven by a step motor whose rotation is controlled by a speed control circuit (not shown) while corresponding to the signal reading operation from the solid-state image sensor.

Further, the shapes of the transmission openings 10 of the filters 7, 8, and 9 of each color are formed as shown in FIG. That is, it is a long hole having an inner end edge and an outer end edge concentric with the rotation center of the turret 6, and each end in the rotation direction, that is, the entry start end 11 and the end end 12 of the entry into the output optical path L are It coincides with the diametrical direction of the turret 6.

Furthermore, the front lens group 2 and the turret 6
A front-stage diaphragm 13 is installed on the output optical path L between the rear-stage lens group 3 and the turret 6, and a rear-stage diaphragm 14 is installed on the output optical path L between the rear-stage lens group 3 and the turret 6. . These diaphragms 13 and 14 have transmission apertures 16 formed in a diaphragm plate 15 having the same shape and size. That is, as shown in FIG. 3, this transmission aperture 16 forms straight edge edges 17 and 18 that pass through the central axis of the turret 6, and the edge 17 is located in the output optical path L of the filter. 7,
It is designed to coincide with the invasion start end 11 of Nos. 8 and 9. Further, the other end edge 18 is the terminal end 1 of the filters 7, 8, 9 when located in the output optical path L.
2. FIG. 3 shows this state. Note that each aperture plate 15 is attached and fixed to a frame (not shown).

Next, the operation of this embodiment will be explained. First, the light emitted from the lamp 1 is turned into a parallel beam by the lens group 2 in the front stage, proceeds along the output optical path L, passes through the transmission aperture 16 of the diaphragm 13 in the front stage, the rotating turret 6, the diaphragm 14 in the rear stage, and then , and is focused by the rear lens group 3 and enters the incident end surface 5 of the light guide 4.

Here, as the turret 6 rotates, R, G, and B filters 7, 8, and 9 are sequentially and intermittently positioned on the output optical path L, and R, G, B is colored sequentially. While receiving such illumination light of each color, each color component image is captured by a solid-state image sensor of an apparatus that sequentially captures each color component image in a frame sequential manner. Further, during the light shielding period, signals from the solid-state image sensor are read out.

By the way, the filter 7 of the turret 6,
The light flux having a circular cross section that enters the diaphragms 8 and 9 and the light flux that exits are transmitted through the transmission apertures 16 and 16 of the apertures 13 and 14, respectively.
16 by each edge 17, 18. In other words, the light beam is cut into a light beam that matches the shape of the entry start end 11 and the end end 12 of the transmission opening 10 of the filters 7, 8, and 9. When the light beam has a circular cross section, it passes through both the entry start end and the end end, and enters the light guide 4 as it is, reducing the light shielding period. , 9 must be shortened to lengthen the blanking period, but according to the present invention, the unnecessary flare portions can be cut by the apertures 13 and 14, and the filters 7, 8, 9
The blanking period can be shortened by making the blanking period longer.

4 and 5 show a second embodiment of the invention. In this embodiment, the apertures 13 and 14 are formed directly on the lens mounting frames 21 and 22 of both the front and rear lens groups 2 and 3. In this way, the number of parts can be reduced and the configuration can be simplified.

In each of the above embodiments, the apertures are installed at the front and rear of the turret, but the present invention is not limited thereto. For example, it may be only on one side. Alternatively, it may be placed near the output end of the lamp, without being adjacent to the turret.

〔Effect of the invention〕

As explained above, according to the present invention, by increasing the light focusing accuracy of the optical system and providing an aperture without changing the shape of the light focusing itself, the blanking period can be easily shortened while having an economical configuration. You can do this. By shortening this blanking period, the amount of transmitted light can be increased. Moreover, the cut of the flare made the photographed images extremely clear.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts of the first embodiment of the present invention, FIG. 2 is a cross-sectional view thereof, FIG. 3 is a front view of the filter and aperture, and FIG. 4 is the second embodiment of the present invention. FIG. 5 is a sectional view of the main parts of the embodiment, and FIG. 5 is a perspective view of the lens mounting frame of the embodiment. 1...Lamp, 2, 3...Lens group, 6...Turret, 7, 8, 9...Filter, 10...Transmission opening, 11...Entry start end, 12...Terminal end,
13, 14...Aperture, 16...Transmission aperture, 17,
18...Edge.

Claims (1)

[Scope of Claims] 1. In a color image photographing illumination device that sequentially illuminates each color of a device that sequentially photographs component images of each color in a frame-sequential method, the illumination device is sequentially positioned by rotation on the output light path from the illumination light source. A turret provided with a filter of each color, and an end edge that conforms to the shape of at least the entry start end and the end of the transmission aperture of the filter when the transmission aperture of the filter of each color is located on the output optical path from the illumination light source. 1. An illumination device for photographing a color image, comprising: a diaphragm having a transmission aperture formed therein. 2. The illumination device for color image photography according to claim 1, wherein the diaphragm is installed adjacent to the turret.