JPH0727121B2 - Solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention is a solid-state imaging device having a light-receiving surface as a light-sensing element array, which obliquely intersects a light beam in the optical path of an imaging optical system and has a center axis around the light beam. A transparent parallel plane plate that can be rotated is disposed, and an image signal is formed by using the output of a plurality of regions around the optical axis detected by each photodetection element as pixels in synchronization with the rotation of the parallel plane plate. With the solid-state image pickup device configured as described above, the number of pixels of the image signal is made larger than the number of pixels of the photodetector array to improve the resolution.

[Industrial application field]

The present invention relates to a solid-state image pickup device, and more particularly, to improvement of a solid-state image pickup device in which a pixel density in an image signal thereof is effectively higher than a density of a photodetector.

The pixel density of the solid-state image pickup device is being increased in order to improve the resolution of the image signal, but there are various restrictions in increasing the density of the photodetector array due to the miniaturization of the pattern, etc. If a means for effectively increasing the density higher than the density of the photodetector array is realized, a great effect can be obtained in improving the resolution.

[Conventional technology]

The semiconductor photodetector has a pn junction and is a photovoltaic type that generates an electromotive force according to incident light, a photoconductive type whose electric resistance changes according to incident light, and a potential well formed on a semiconductor substrate. Although there is a MIS type or the like in which carriers corresponding to light are accumulated, in a solid-state image pickup device, photodetection elements are usually arranged in a two-dimensional array.

An image of an object to be imaged is formed on the light receiving surface of this two-dimensional photodetector array by an image pickup optical system, and an electric signal corresponding to incident light is obtained from each photodetector.
In step D), the image signals are time-sequentially multiplexed and sequentially detected to form an image signal.

Since the means for accumulating and transferring electric charges is required in this way, the light receiving area of the photodetector is greatly limited, and the ratio to the pixel area obtained by equally dividing the image plane into a matrix is, for example, 25%.
It has stopped to some extent.

[Problems to be solved by the invention]

In order to improve the resolution of the image signal, the element density of the photo-detecting element array is increased by pattern reduction, and charge storage and transfer means are improved for that purpose. It is not desirable to secure the quantity, and the large increase in density by this method is very limited.

Under such circumstances, it is an object of the present invention to significantly improve the resolution of an image by effectively increasing the pixel density of the image signal more than the density of the photo detector.

[Means for solving problems]

The above-mentioned problem is a solid-state imaging device having a light-receiving surface as an array of light-sensing elements, which is a transparent plane-parallel plate that obliquely intersects the light beam in the optical path of the imaging optical system and can rotate around the central axis of the light beam. In the present invention, an image signal is formed with the outputs of a plurality of regions around the optical axis detected by the individual photo-sensing elements as pixels in synchronism with the rotation of the plane-parallel plate. It is solved by a solid-state imaging device.

[Action]

FIG. 1 is a schematic diagram showing a solid-state imaging device according to the present invention. FIG. 2A is a schematic diagram showing the structure of the image pickup unit.
Is an image pickup optical system, 3 is a two-dimensional photodetector array, and 1
Is a transparent plane-parallel plate that rotates obliquely to the optical axis of the imaging optical system 2. Also, FIG. 2B is a partial schematic plan view of the two-dimensional photodetector array 3, in which 3A, 3B, 3C and the like indicated by diagonal lines are photodetector elements, and 3Aa, 3Ab, 3Ac, 3Ad and the like indicated by broken lines are parallel planes. 3 shows pixels of an image to be captured when the face plate 1 is not provided.

In this way, when the light rays are obliquely incident on the plane-parallel plate 1, the emitted light is shifted in parallel to the incident light, so that, for example, the pixel 3Aa of the image to be imaged can be incident on the photodetector 3A, If the plane-parallel plate 1 rotates around the optical axis, for example, the pixels of the image to be imaged incident on the photodetector 3A will be 3Aa → 3Ab →
It moves sequentially from 3Ac to 3Ad.

Therefore, if the output of the light detecting element 3A is detected in synchronization with the rotation of the plane-parallel plate 1, the areas 3Aa, 3Ab, 3Ac, 3Ad of the image to be imaged are detected.
The electric signals corresponding to are successively obtained.

〔Example〕

 The present invention will be specifically described below with reference to examples.

FIG. 2 is a schematic view showing an embodiment of the present invention, in which 1 is a plane parallel plate, 11 is a drum, 12 is a motor, 13 is a synchronizing signal generating circuit, 2 is an image pickup optical system, and 3 is a two-dimensional photodetector. array,
4 is a signal detection circuit, 5 is an analog / digital converter,
6a, 6b, 6c and 6d are frame memories.

In this embodiment, the plane-parallel plate 1 is mounted in a drum 11, and the drum 11 is rotated by a motor 12 around its central axis that coincides with the optical axis of the image pickup optical system 2. The phase of the plane-parallel plate 1 (drum 11) is detected by, for example, an optical method, and is synchronized with the control pulse of the signal detection circuit 4 such as CCD by a synchronizing signal.

In this embodiment, as shown in FIG. 1 (b), each element of the two-dimensional photodetector array 3 detects four pixels of the image to be picked up. The upper left pixel a, the lower left pixel b, the lower right pixel c, and the upper right pixel d are sequentially detected.

The signals read from the signal detection circuit 4 are the pixels a, b,
It is time-sequentially multiplexed for each of c and d, and a frame memory is temporarily provided for each pixel a, b, c, and d after analog / digital conversion.
The data is accumulated in 6a, 6b, 6c, and 6d and read out in the pixel array order of the image to be captured. The subsequent signal processing may be the same as the conventional method.

The material of the plane-parallel plate 1, the thickness, etc., the inclination angle with respect to the optical axis, etc. are selected and set according to the purpose.
Sapphire (Al ₂ O ₃ ) in the infrared band of ~ 5 μm
Is used, the refractive index n≈1.76, the thickness d shown in FIG. 3 (a), and the silt amount r of the emitted light with respect to the incident angle α are shown in FIG. 3 (b).
The shift amount of several tens to 100 μm is easily realized.

As is clear from the above description, this embodiment has the effect of increasing the number of pixels of the image signal to four times the number of pixels of the photodetector array. Moreover, an area about three times as large as the light receiving area of each light detecting element can be used for the CCD or the like, and a device having a margin for the amount of transferred charges can be easily realized.

It should be noted that in the above-described embodiment, four pixels of the image to be picked up are detected by one light detecting element, but this correspondence can be selected variously according to the purpose.

〔The invention's effect〕

As described above, according to the present invention, the effect of significantly increasing the number of pixels of the image signal with respect to the number of pixels of the photodetector array can be obtained, and the resolution can be dramatically improved by the high density image signal. It will be possible.

Moreover, a sufficient margin is provided for the pattern formation of the photodetector array, and it is easy to realize the effect by applying it to a wide range of application fields such as visible light imaging and long-wavelength infrared thermography.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a solid-state image pickup device according to the present invention, FIG. 1A is a schematic diagram showing the structure of its image pickup portion, and FIG. 1B is a partial schematic diagram of a photodetector array. FIG. 3 is a plan view, FIG. 2 is a schematic view of an embodiment of the present invention, and FIGS. 3 (a) and 3 (b) are views showing examples of the shift amount of emitted light by a plane-parallel plate. In the figure, 1 is a rotating parallel plane plate, 2 is an imaging optical system, 3 is a two-dimensional photodetector array, 3A, 3B, 3C, etc. are photodetectors, 3A.
a, 3Ab, 3Ac, 3Ad, etc. are pixels of the image to be captured, 4 is a signal detection circuit, 5 is an analog / digital converter, 6a, 6b, 6c, 6
d is a frame memory, 11 is a drum, 12 is a motor, and 13 is a synchronizing signal generating circuit.

Claims (1)

[Claims] 1. A solid-state imaging device having a light-receiving surface as an array of light-sensing elements, the transparent plane-parallel plate being oblique to the light flux in the optical path of the imaging optical system and rotatable about the central axis of the light flux. Is arranged, and an image signal is formed with the outputs of a plurality of regions around the optical axis detected by the individual photo-sensing elements as pixels in synchronism with the rotation of the plane-parallel plate. Solid-state imaging device.