JPH06133229A - Solid-state image pickup element having micro lens - Google Patents

Abstract

PURPOSE:To prevent shading caused at an end of screen. CONSTITUTION:A micro lens section 13 having lots of micro lenses 12 is arranged on the side of a light receiving face and at least left/right ends of a CCD 10 are bent toward a light incident side at a prescribed curvature together with the micro lens section 13. Thus, a major ray is led in a direction perpendicular to a tangent at an apex of the micro lens 12 and then shading is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a solid-state image pickup device having a microlens, which is disposed in an electronic endoscope or the like.

[0002]

2. Description of the Related Art Electronic endoscopes used in the medical field and industrial field are well known. In this electronic endoscope, a CCD (Charge Coupled Device) which is a solid-state image pickup device is arranged at the tip. . According to this, when the irradiation light is guided into the body to be observed, the image of the body to be observed is captured by the CCD, and the inside of the body cavity such as the digestive tract can be displayed on the monitor.

FIG. 3 shows a conventional interline type CC.
The configuration of D is shown and, as shown, CCD1
A large number of photosensors 2 corresponding to one pixel are arrayed therein. A vertical transfer line 3 for transferring charges proportional to the amount of light of the photosensor 2 is provided for each column of the photosensors 2, and a horizontal transfer line 4 for sequentially outputting charges from the vertical transfer lines 3 is provided. To be Therefore, the light incident from the optical system member of the electronic endoscope is detected by the photosensor 2, and the image information is captured by the signal charge. After the signal charge is transferred to the vertical transfer line 3, the light is parallelized. When sequentially transferred to the horizontal transfer line 4, the video signal is output from the horizontal transfer line 4.

FIG. 4 shows an optical system member and a CCD of a conventional electronic endoscope. The optical system member 6 and the CC shown in FIG.
D1 is closely arranged because it needs to be compactly housed in the tip of the electronic endoscope, and the optical system member 6 has a focal length f of 2
It is set to about 3 mm. Further, a microlens 7 is formed on the upper surface of the CCD 1 by a photolithography method or the like, and the light incident from the optical system member 6 is efficiently condensed by the microlens 7 so that the sensitivity can be improved. There is.

[0005]

However, in the above-mentioned conventional electronic endoscope, the focal length f of the optical system member 6 is f =
Since the length is extremely short such as about 2 to 3 mm, there is a problem that the microlens 7 causes shading 100 mainly at the left and right ends of the screen 9, as shown in FIG. That is, since the focal length f of the optical system member 6 is short, the light rays emitted from the diaphragm 8 in FIG.
When viewed from one pixel, it has a considerably wide viewing angle, and a light ray is obliquely incident on the end of the microlens 7 or the light receiving surface of the CCD 1. Then, since the microlens 7 provided for each pixel has a bilaterally symmetric spherical shape, light incident from an oblique direction of the microlens 7 does not reach the light receiving surface satisfactorily.
As a result, the shading 100 becomes darker toward the end of the CCD 1, that is, the end of the screen 9.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a solid-state image pickup device having a microlens capable of preventing shading which occurs at the edge of the screen.

[0007]

In order to achieve the above object, a solid-state image pickup device having a microlens according to the present invention has a microlens portion disposed on the light-receiving surface side thereof and at least light incident on the left and right ends thereof. It is characterized in that it is bent to a side with a predetermined curvature.

[0008]

According to the above construction, for example, the solid-state image pickup element is formed with a predetermined radius of curvature together with the microlens portion, so that the light beam emitted from the exit pupil of the optical system member is CCD.
The light will be incident from the apex of the microlens even at the end of. Therefore, the light ray from the exit pupil reaches the light receiving surface favorably and shading is prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a solid-state image pickup device having a microlens according to the embodiment, and FIG. 2 is a conceptual diagram showing the relationship between an optical system member and the solid-state image pickup device. In the figure, in the CCD 10 which is a solid-state image pickup device, as in the conventional case, magenta (M), cyan (Cy), green (G), yellow (Ye), etc. are formed on a light receiving surface (image area) 11 formed of a photo sensor. Is formed, and a large number of microlenses 1 are formed on the color filter.
The microlens portion 13 forming 2 is arranged. As shown in FIG. 2, the microlens 12 has a spherical shape with a predetermined curvature, and is formed by a photolithography method or the like so as to be provided for each pixel.

Then, as described above, the microlens portion 1
In the state where 3 is provided, the entire CCD 10 is bent with a predetermined radius of curvature. In the figure, the radius of curvature is shown as small so that the bending state can be seen,
Actually, it has a larger radius of curvature. As mentioned above,
The light beam emitted from the diaphragm 14 of the optical system member 6 can be regarded as parallel light at the central portion, but is incident on the light receiving surface with a slight inclination at the end portion. It suffices to bend the CCD 10 so that the lens 12 faces the incident ray direction.

That is, as shown in the enlarged view of FIG. 2B, the chief ray 200 is tangential to the apex of the microlens 12.
Together with the microlens portion 13 so that
D10 is bent. According to this, even with the microlenses 12 at the left and right ends, the microlenses 1 at the center are
Under the condition equivalent to 2, the light reaching from the optical system member 6 can be guided to the light receiving surface.

In the above embodiment, the CCD 10 is formed after the microlens portion 13 is formed.
The microlens portion 13 can be formed later along the bent surface on the light receiving surface of the bent CCD 10. Also,
Although the entire CCD 10 is bent with a predetermined radius of curvature, only the left and right ends may be bent with a predetermined curvature.

Further, the CCD 10 may be housed in a CCD package. In this case, a groove is formed on the bottom surface of the housing of the package according to the bending state of the CCD 10, and the CCD 10 is housed in this groove. Of course, the package itself can be bent like the CCD 10.

[0014]

As described above, according to the present invention,
Since at least the left and right end portions are bent with a predetermined curvature toward the light incident side together with the microlens portion arranged on the light receiving surface side, the chief ray is vertically incident on the light receiving surface from the apex of the microlens, and the end portion It is possible to favorably prevent shading that occurs in 1.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a solid-state imaging device having a microlens according to an embodiment of the present invention.

FIG. 2A is a conceptual diagram showing a relationship between an optical system member and a CCD of the embodiment, and FIG. 2B is an enlarged view of a microlens.

FIG. 3 is a diagram showing a configuration of a conventional interline CCD.

FIG. 4 is a diagram showing a conventional CCD and an optical system member.

FIG. 5 is a diagram for explaining shading on a screen.

[Explanation of symbols]

 1, 10 ... CCD, 7, 12 ... Microlens, 13 ... Microlens part, 100 ... Shading, 200 ... Chief ray.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area H01L 27/14

Claims (1)

[Claims] 1. A solid-state image sensor having a microlens portion disposed on the light-receiving surface side, and a microlens having at least left and right end portions bent toward the light incident side with a predetermined curvature.