JPH07298146A - Solid-state image pickup element and endoscope using the solid-state image pickup element - Google Patents

Abstract

PURPOSE:To improve the light receiving sensitivity of the endoscope by providing correction lenses such as a flat, convex lens, Fresnel lens and a rod lens array to an incident side of a light receiving section so as to make an incident light incident only the light receiving section nearly perpendicularly. CONSTITUTION:Since correction lenses such as a flat, convex lens, Fresnel lens and a rod lens array are arranged to the optical incidence part in the solid-state image pickup element, the incident angle of the incident light made incident onto a micro lens array is set close to a vertical angle. That is, the flat convex lens 11 is arranged in place of a cover glass. A light incident face of the lens 11 is formed flat and a light emission face of the lens 11 is formed to be a convex shape. In the CCD formed as above, even when an incident light 12 is made incident at an incident angle, the flat projection lens 11 is used to compensate the state. A light incident face of the Fresnel lens 13 is formed flat and its emission face is a sawtooth projected face, the incident angle of the incident light is made almost vertical and the thickness of the lens is made remarkably thin by adopting a sawtooth shape for the projection face.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device such as a CCD mounted on a distal end of a scope of an endoscope apparatus, and more particularly to a technique for improving light receiving sensitivity.

[0002]

2. Description of the Related Art In recent years, endoscope devices have been widely used as medical diagnostic devices have been developed. As shown in FIG. 4, the endoscope apparatus includes a scope 101, an operation unit 102,
Connector 104 for connecting to a console (not shown)
Etc., and a solid-state image sensor is mounted on the tip portion 103 of the scope 101 to receive light from a subject.

FIG. 5 is a sectional view showing the structure of a conventional CCD as a solid-state image pickup device. As shown in the figure, this CCD has a light receiving element chip 3 formed by arranging a plurality of light receiving elements 3a, an opening 2 for introducing light into each light receiving element 3a, and incidence on each light receiving element 3a. The cover glass 5 includes a microlens array 1 in which a plurality of microlenses 1a for converging light are arranged. Then, the light from the subject is received by the microlens array 1 via the cover glass 5, the incident light is converged on each light receiving element 3a by each microlens 5a, and photoelectric conversion is performed by each light receiving element 3a to perform image processing side. To transmit.

FIG. 6 is an explanatory view showing the path of incident light 6 which is incident on the microlens 1a. FIG. 3A shows the case where the incident light 6 enters from the vertical direction, and the incident light 6 is converged by the microlens 1a and introduced into the opening 2 from the vicinity of the center. However, if the incident light 6 is incident at an angle as shown in FIG.
Will not be introduced into the opening 2, and the light receiving sensitivity will decrease.

[0005]

As described above, in the conventional solid-state image pickup device, when the incident angle of the incident light 6 becomes large, the entire incident light 6 cannot be received, and the light receiving sensitivity is lowered. There was a drawback that it would end up. Then, in an endoscope apparatus using such a solid-state image pickup device, there is a problem that the image may be dark and the diagnostic ability may be deteriorated.

The present invention has been made in order to solve such a conventional problem, and an object thereof is to provide a solid-state image pickup device capable of improving light receiving sensitivity and an endoscope apparatus using the same. To provide.

[0007]

In order to achieve the above object, a solid-state image sensor according to the first invention of the present application is a light-receiving element chip in which a plurality of light-receiving elements are arranged in a plane, and a light-receiving element chip In a solid-state imaging device having a lens array provided on the incident side and having a plurality of microlenses for converging the incident light on each light receiving element, the incident angle of the incident light is corrected on the light incident side of the lens array. A characteristic is that a correction lens is provided for this purpose.

The solid-state image sensor according to the second invention of the present application is
In the first invention, the correction lens is a plano-convex lens having a flat incident surface and a convex exit surface.

Further, the solid-state image pickup device of the third invention of the present application is
In the first invention, the correction lens is a Fresnel lens.

The solid-state image sensor according to the fourth aspect of the present invention is
In the first invention, the correction lens is a rod lens array.

Further, the endoscope apparatus according to the present invention is characterized in that the solid-state image pickup device according to any one of the first to fourth inventions is arranged at the distal end portion of the endoscope.

[0012]

According to the solid-state image pickup device of the present invention constructed as described above, the correction lens such as the plano-convex lens, Fresnel lens, and rod lens array is arranged on the light incident side, so that the incident light enters the microlens array. The incident angle of light is made close to vertical. Therefore, the light receiving sensitivity of the light receiving element chip is significantly improved.

Further, if such a solid-state image pickup device is mounted on the distal end portion of the scope of the endoscope apparatus, the brightness of the image is increased and the diagnostic ability is improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a solid-state image sensor (CCD) showing a first embodiment of the present invention. As shown, in this embodiment, a plano-convex lens 11 is provided instead of the cover glass 5 as compared with the conventional CCD shown in FIG. The plano-convex lens 11 has a flat incident surface and a convex exit surface. Further, since the light receiving unit 4 is the same as the conventional example shown in FIG. 5, the same reference numerals are given and the description thereof will be omitted.

In the CCD thus constructed,
Even if the incident light 12 is incident with a certain incident angle,
The light is refracted by the plano-convex lens 11 and is introduced into the light receiving unit 4 substantially vertically. Therefore, as shown in FIG. 6B, incident light does not leak from the opening 2 and the light receiving sensitivity is improved.

FIG. 2 is a block diagram showing a second embodiment of the present invention. In this embodiment, a Fresnel lens 13 is used instead of the plano-convex lens 11. Fresnel lens 13
Has an entrance surface formed in a flat shape and an exit surface formed in a sawtooth convex surface. Therefore, the incident angle of the incident light can be made substantially vertical as in the case of the first embodiment, and the lens can be made extremely thin by forming the convex surface into a sawtooth shape.

FIG. 3 is a block diagram showing a third embodiment of the present invention. In this embodiment, a rod lens array 14 configured by arranging a plurality of rod lenses 14a on a plane is used as a means for controlling the incident light to be vertical. The rod lens 14a, as shown in FIG.
5 is a lens configured by laminating different materials so that the material 5 is refracted and gradually faces inward. Even in such a configuration, the incident light can be made substantially vertical as in the first and second embodiments, so that the light receiving sensitivity is improved.

Further, if the solid-state image pickup device of the above-mentioned first to third embodiments is mounted on the distal end portion of the scope of the endoscope apparatus, the brightness of the image is increased as the light receiving sensitivity is improved.
An image that is easy to diagnose can be obtained.

[0019]

As described above, according to the present invention,
Since the incident light incident on the solid-state image pickup device can be introduced into the light receiving portion substantially vertically, the light receiving sensitivity of the light receiving device is improved. Then, if this solid-state imaging device is adopted in an endoscope device, an image can be made bright. Also, there is no need to add electrical processing as much as the sensitivity improves,
It becomes possible to reduce noise.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a first embodiment of a solid-state image sensor to which the present invention is applied.

FIG. 2 is a sectional view showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is a sectional view showing a configuration of a third exemplary embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an endoscope.

FIG. 5 is a cross-sectional view showing a configuration of a conventional solid-state image sensor.

FIG. 6 is an explanatory diagram showing an incident angle and a path of incident light.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Microlens array 2 Aperture 3 Light receiving element chip 4 Light receiving section 5 Cover glass 6, 12, 15
Incident light 11 Plano-convex lens 13 Fresnel lens 14
Rod lens array 101 Scope 103 Tip part

Claims (5)

[Claims] 1. A light-receiving element chip having a plurality of light-receiving elements arranged in a plane, and a plurality of microlenses provided on the light-incident side of the light-receiving element chip for converging incident light on each light-receiving element. In the solid-state imaging device having the above described lens array, a correction lens is arranged on the light incident side of the lens array to correct the incident angle of the incident light. 2. The solid-state image sensor according to claim 1, wherein the correction lens is a plano-convex lens having a flat incident surface and a convex exit surface. 3. The solid-state image sensor according to claim 1, wherein the correction lens is a Fresnel lens. 4. The solid-state image sensor according to claim 1, wherein the correction lens is a rod lens array. 5. An endoscope apparatus in which the solid-state imaging device according to claim 1 is arranged at a tip portion of an endoscope.