JPH05142484A - Electronic endoscope - Google Patents

Abstract

PURPOSE:To cut off stray light and improve the resolution of an image which is displayed on a monitor by providing at least part of the filter group of an electronic endoscope with a visual field mask for stray light removal. CONSTITUTION:An objective group 1, the filter group 2, a prism 3, and a CCD unit 4 are provided at the tip 6 of the electronic endoscope 6, and the visual field mask 5 for the rear surface prism 3 of the filter group 2 is mounted. The objective group 1 is constituted by combining >=2 concave and convex lenses, and the filter group 2 consists of an optical low-pass filter for removing a color false signal, a visual field sensitivity characteristic filter which provides optimum color reproduction by correcting the sensitivity characteristics of the CCD, and a laser light cutting filter which prevents an output from being saturated owing to the incidence of treatment laser light on the CCD, etc. The visual field mask removes the stray light, so no false image is formed in the image displayed on the monitor. Consequently, the precision of a diagnosis is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope having a structure in which a solid-state image sensor is mounted on the tip of an endoscope.

[0002]

2. Description of the Related Art Electronic endoscopes can be roughly divided into a main body and an endoscope scope. When the inside of the body cavity of a subject is imaged using this electronic endoscope, the endoscope is inserted into the body cavity of the subject, and the light guide is placed from the device body to the tip of the endoscope. While illuminating the specimen, a solid-state image sensor (CCD) captures an image through an optical system, and the captured content is displayed on a monitor based on the electric signal obtained by the CCD.
In such an electronic endoscope, as a structure of the tip portion of the endoscope, for example, as shown in FIG. 6, an optical low-pass filter for removing a color false signal or the color of the CCD is provided between the objective lens group 1 and the CCD 4. A structure in which a filter group 2 including a visibility correction filter for adjusting reproducibility, a laser cut filter for cutting laser light for treatment, and a prism 3 for optical path conversion are arranged is adopted.

[0003]

However, in the case of such an objective optical system structure at the distal end portion of the endoscope, as shown in FIG. 7, a light beam having a large angle of view outside the field of view is totally scattered on the side surface of the filter group or inside the prism. It is reflected and enters the field of view as stray light, which causes a false image in the image displayed on the monitor. Therefore, conventionally, there is a problem that the resolution of the image displayed on the monitor is deteriorated.

The present invention has been made in view of the above problems, and an object thereof is to block stray light and improve the resolution of an image displayed on a monitor.

[0005]

In order to solve the above-mentioned problems, the present invention can perform various optical processes on the light which is interposed between the objective lens group and the CCD and has passed through the objective lens group. An electronic endoscope including a filter group is characterized in that a field mask for removing stray light is provided on at least a part of the filter group.

[0006]

Since the stray light is removed by the field mask, no false image is generated in the image displayed on the monitor.

[0007]

【Example】

<Embodiment 1> FIG. 1 is a view showing the schematic arrangement of an embodiment of the distal end portion of the electronic endoscope of the present invention. The distal end portion 6 of the electronic endoscope has an objective lens group 1, a filter group 2, a prism 3 and a CCD unit 4, while a field mask 5 for the prism 3 is mounted on the rear surface of the filter group 2. Here, the objective lens group 1 is a combination of two or more concave and convex lenses, and the filter group 2
Is an optical low-pass filter for removing a color false signal, a luminosity characteristic filter for correcting the sensitivity characteristic of the CCD for optimum color reproduction, and a laser beam for treatment is C
It is composed of a laser cut filter or the like for preventing the output from being saturated when it enters the CD. The prism 3 is a member for performing optical axis conversion, and when viewed from the incident surface side, it has a trapezoidal shape as shown in FIG. 2 or a rectangular shape. CC
The D unit 4 is composed of a cover glass 4a for protecting the CCD and a solid-state image sensor (CCD) 4b, and has a rectangular shape in the direction of the arrow in FIG. As the visual field mask 5, a metal such as phosphor bronze or stainless steel which is subjected to masking vapor deposition (or mask formation by etching) on the rear surface of the filter group, or a mask which is coated with a black paint such as epoxy is used.

The visual field mask 5 is provided on the rear surface of the filter group 2 because, as shown in FIG. 3, it becomes easier to separate an effective ray and a stray ray from each other as they are closer to the image forming point.
A solid line portion in FIG. 3 indicates an effective light ray, and a dotted line portion indicates a stray light ray. Further, in FIG. 3, a prism is not placed behind the filter group 2, but since the prism is only for optical path conversion, in this case, the presence or absence of the prism has no effect and is therefore omitted.

Since the stray light can be blocked while making use of the effective light rays by the visual field mask 5 in the above-mentioned device, no false image is generated in the image displayed on the electronic endoscope monitor, and the resolution of the image is improved. .

<Embodiment 2> In addition to the visual field mask 5 installed behind the filter group 2 in the first embodiment, a similar visual field mask 7 is provided on the front surface of the filter group 2 as shown in FIG. Set up. This is intended to block stray light reflected on the side surface of the filter group 2 particularly on the front surface of the filter group 2. By using the visual field mask 7 together with the visual field mask 5 on the rear surface of the filter, stray light can be more surely removed. As a result, a false image does not occur in the image displayed on the electronic endoscope monitor, and the image resolution is improved.

<Embodiment 3> Instead of the visual field mask 7 installed on the front surface of the filter group in the above Embodiment 2, as shown in FIG. Good. As a result, the reflectance on the side surface of the filter group 2 is reduced, so that stray light reflected on the side surface of the filter group can be blocked, as in the case of the visual field mask 7 of the second embodiment.

By this method, stray light can be more surely removed. As a result, a false image does not occur in the image displayed on the electronic endoscope monitor, and the image resolution is improved.

[0013]

As described above, according to the present invention,
Since it is possible to remove only the stray light while making use of the effective light rays by the visual field mask or the like, the resolution of the image displayed on the electronic endoscope monitor is improved. As a result, the accuracy of diagnosis can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of an electronic endoscope scope distal end portion of the present invention.

FIG. 2 is a view of the prism 3 in FIG. 1 viewed from the incident surface.

FIG. 3 is a diagram showing an example of an effective light beam and a stray light beam at the tip of the electronic endoscope.

FIG. 4 is a schematic configuration diagram according to a second embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a third embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a conventional electronic endoscope scope distal end portion to which the present invention is not applied.

FIG. 7 is a diagram showing an example of stray light in FIG.

[Explanation of symbols]

 1 Objective lens group 2 Various filter groups 3 Optical path conversion prism 4 Solid-state image sensor (CCD) unit 5 Field mask for prism 6 Endoscope scope tip 7 Field mask for side of filter group 8 Grain, black paint etc. Filter group side

Claims (1)

[Claims] 1. An electronic endoscope provided with a filter group interposed between an objective lens group and a solid-state imaging device and capable of performing various optical processes on light passing through the objective lens group, wherein: An electronic endoscope, wherein a field mask for removing stray light is provided on at least a part of the group.