JPH10262174A - Solid-state image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the improvement of the resolution from being limited in the case of increasing the number of equivalent pixels in comparison with the substantial resolution that is determined by the number of pixels of a solid-state image pickup element. SOLUTION: Solid-state image pickup elements 15, 16 are arranged respectively to light emission faces 145, 146 of an optical prism 14 such that a size of an aperture of a light receiving section of one pixel is nearly 1/n (n=2,3,...) of a pixel interval in both horizontal and vertical directions and the relative position of the elements is deviated by 1/n of the pixel interval in both the horizontal and vertical directions. Piezoelectric elements 17, 18 displace the relative position between optical information and the light receiving section of each solid-state image pickup element at an interval of 1/n of the pixel interval or at an integer multiple of it at least in one of the horizontal and vertical directions. A circuit processing an output of each solid-state image pickup element applies integral processing to the video information sets received at respective relative positions between the optical information and the light receiving section of each solid-state image pickup element to obtain a high resolution video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a solid-state image pickup device using a solid-state image pickup device (for example, a CCD image pickup device) and capable of obtaining a resolution higher than the resolution determined by the original number of pixels of the solid-state image pickup device. .

[0002]

2. Description of the Related Art Solid-state imaging devices using a solid-state imaging device such as a CCD imaging device are now specially used because of their small size, light weight, low power consumption, easy handling, and good uniformity of resolution within a screen. Except for a very small number of fields, imaging devices have become mainstream. The same applies to the field of an X-ray imaging apparatus that converts image information based on X-rays into visible light using an X-ray image intensifier or the like, and captures the visualized moving image.

The resolution of these solid-state imaging devices is basically determined by the number of pixels of the solid-state imaging device. On the other hand, since the chip size of the solid-state imaging device is limited to a certain size from the viewpoint of manufacturing, when the number of pixels increases, the size per pixel is inevitably reduced, and the sensitivity performance deteriorates accordingly. Problems arise. Therefore, conventionally, a solid-state imaging device that can obtain a video signal with a higher resolution than the original resolution determined by the number of pixels of the solid-state imaging device has been put into practical use by devising the system of the solid-state imaging device (for example, reference 1: Harada, Others: “Swing CCD image sensor”, Journal of the Institute of Television Engineers of Japan, 37, 10, pp. 826-832,
Oct. 1983, Reference 2: Yamanaka, et al .: "One method of 3CCD color camera", Journal of the Institute of Television Engineers of Japan, 33,
7, pp. 516-522, July 1979). Literature 1 is a method in which the number of pixels is equivalently increased by periodically displacing the position of a CCD image sensor using a bimorph piezoelectric element. Reference 2 discloses a method in which the number of pixels is equivalently increased by shifting the relative positions of CCD image sensors arranged on a plurality of light exit surfaces of an optical color separation prism.

[0004] These conventional techniques have the following problems. That is, each of the above-mentioned means alone has a limitation on the movement position control characteristics and the spatial alignment accuracy, and furthermore, the equivalently increased light receiving portions of pixels overlap each other, resulting in an improvement in resolution. Due to the so-called aperture effect, the increase in the equivalent number of pixels was limited to a doubling in both the horizontal and vertical directions (2 × 2 = 4 as a whole). Further, this problem has not been improved merely by combining the above two methods.

[0005]

As described above, in the conventional solid-state imaging device, optical information from a subject and light reception on the solid-state imaging device are required to improve resolution characteristics without increasing the number of pixels of the solid-state imaging device. A method has been adopted in which the relative number of pixels is moved or shifted to increase the equivalent number of pixels. However, there has been a problem that the light receiving portions of the pixels that have been equivalently increased overlap between adjacent pixels, and the improvement in resolution is limited due to the so-called aperture effect.

Accordingly, the present invention has a problem that the improvement in resolution is limited when the equivalent number of pixels is increased by devising the system, compared to the original resolution determined by the number of pixels of the solid-state imaging device. It is an object of the present invention to provide a solid-state imaging device that improves the above.

[0007]

In order to achieve the above object, a solid-state imaging device according to the present invention comprises the following means. That is, at least two solid-state imaging devices in which the size of the aperture of the light receiving section in one pixel is substantially 1 / n (n = 2, 3,...) Of the horizontal and vertical pixel intervals in both the horizontal and vertical directions. use. They are arranged on different light exit surfaces of an optical system such as an optical prism such that their relative positional relationship is shifted by 1 / n of the pixel interval in the horizontal and vertical directions in both the horizontal and vertical directions. Then, the relative positional relationship between the optical information from the subject and the light receiving unit on each of the solid-state imaging devices is determined in at least one of the horizontal and vertical directions by 1 / n or an integer of 1 / n of the pixel interval in that direction. Means for displacing at twice the distance, and integrating the optical information from the object and the image information captured at each position of the relative positional relationship between the light receiving unit on each of the solid-state imaging devices to obtain one high resolution Means for synthesizing video signals.

[0008] The solid-state imaging device according to the present invention has an X
An image conversion unit such as an X-ray image intensifier that converts image information from a line into a wavelength in the visible light region, and captures optical information in the visible light region output from the image conversion unit. I do.

According to such means, when the equivalent number of pixels is increased by a device of the system compared with the original resolution determined by the number of pixels of the solid-state imaging device, the improvement of the resolution is limited. Problem can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the solid-state imaging device according to the present invention. Reference numeral 11 denotes an X-ray imaging intensifier, to which input X-ray information from an X-ray tube is input, though not shown in the figure. The output of the X-ray image intensifier 11 becomes an optical image in the visible light region, and enters the optical prism 14 via the optical lens system 12. The optical prism 14 splits the incident light into two, one of which is the light exit surface 1
After being output to 45, an image is formed on the CCD image pickup device 15.
The other of the two light beams incident on the optical prism 14 is output to the light exit surface 146 and then imaged on the CCD imaging device 16. These CCD image pickup devices 15 and 16 apply the pulse from the pulse generation circuit 31 to the CCD driving circuit 30 and input the CCD driving pulse output from the pulse driving circuit 31 to thereby input the optical image. Convert to electrical signals.

Piezoelectric actuators 17 and 18 are attached to an image pickup block 13 composed of CCD image pickup devices 15 and 16 and an optical prism 14. These piezoelectric actuators 17 and 18 receive pulses from the pulse generation circuit 31 and input to the actuator drive circuit 29,
When a pulse for driving the actuator output therefrom is input, the actuator is slightly displaced in the directions indicated by the arrows (vertical direction, horizontal direction). As a result, the structure is such that the imaging block 13 is slightly displaced. The piezoelectric actuator 17 is arranged to displace the imaging block 13 in the vertical direction of the image, and the piezoelectric actuator 18 is arranged to displace the imaging block 13 in the horizontal direction of the image.

Output signals from the CCD image pickup devices 15 and 16 are amplified to predetermined levels by preamplifiers 19 and 20, respectively, and then converted to digital signals by analog-digital (hereinafter, referred to as A / D) converters 21 and 22. Is converted to After each image data is stored in the memories 23 and 24, the resolution is increased by the resolution increasing processing circuit 25. After that, a non-linear process such as gamma correction is performed in a process circuit 26, input to a D / A converter 27, converted into an analog signal, and output from an output terminal 28.

Next, the relative positional relationship between the CCD image sensors 15 and 16 will be described. FIG. 2 is a diagram for explaining the size of the light receiving section in one pixel, and FIG.
It is a figure for explaining the relative positional relationship of 5 and 16.
In FIG. 2, Ph and Pv are the lengths of one pixel in the horizontal and vertical directions, respectively.
The vertical length. In FIG. 2, there is a general relationship of Dh = Ph / 4, Dv = Pv / 4.

In FIG. 3, "A" is a CCD image sensor 16
And “B” indicates a light receiving unit of the CCD image sensor 15. That is, the two CCD image pickup devices 15 and 16 having the light receiving units having the above-mentioned sizes are optically shifted relative to each other by Ph / 4 in the horizontal direction and by Pv / 4 in the vertical direction. Light exit surface 145 of prism 14
And 146.

Next, an image pickup block 13 in which the two CCD image pickup devices 15 and 16 are displaced as described above,
The displacement amount and displacement direction when displacing by the piezoelectric actuators 17 and 18 will be described.

FIG. 4 shows an X-ray image intensifier 1
FIG. 2 is a diagram for explaining a positional relationship between an output optical image of No. 1 and an imaging block 13. First, FIG. 7A shows the position at time t1. For simplification of illustration, only the light receiving unit is shown. First, optical information is obtained at this position. Next, FIG. 2B shows the position at time t2. A portion surrounded by a broken line indicates a position at time t1, and P
It can be seen that it is shifted by h / 2. Optical information is obtained at this position as in the case of time t1. Next, FIG. 3C shows the position at time t3. The part surrounded by the broken line is (b)
5 shows the position at time t1. Time t2
It can be seen that the position is shifted downward by Pv / 2. Optical information is obtained at this position in the same manner as at times t1 and t2. Next, FIG. 4D shows the position at time t4. The portion surrounded by the broken line indicates the position at the time t1 similarly to the above. From the position at time t3, P
It can be seen that it is shifted by h / 2. Times t1, t2,
As in the case of t3, optical information is obtained at this position. Then, although not shown, after a predetermined time from time t4, it is displaced upward by Pv / 2, returns to the original position at time t1, and the displacement is repeated thereafter.

FIG. 1E shows the optical information captured at these four positions combined into one. As can be seen from this figure, the pixel density is eight times the original number of pixels of the CCD image sensor. This integration is performed by the memories 23 and 24 and the high-resolution processing circuit 25 shown in FIG.

In FIG. 4 (e), there is a portion having no image information. However, if necessary, the pixel density is increased by a factor of 16 with respect to the original number of pixels of the CCD image pickup device by performing interpolation from neighboring pixels. Up to As the interpolation processing, for example, there is a method of employing an average of two pixels above and below a target pixel.

As described above, in the above-described embodiment, the solid-state imaging device in which the size of the light receiving portion in one pixel is 1/4 of the horizontal and vertical length of one pixel in both the horizontal and vertical directions. Using two elements, their relative positional relationship is horizontal,
The optical prism was arranged on the light exit surface of the optical prism so as to be shifted by a 1/4 pixel interval in the vertical direction. Further, the imaging block section including the optical prism and the solid-state imaging device can be minutely displaced in the horizontal and vertical directions using a piezoelectric actuator. Thus, the relative positional relationship between the optical information to be imaged and the light receiving unit on each solid-state image sensor was displaced up, down, left, right, and up by 1/2 pixel intervals. And by integrating the video data obtained at these positions,
A video signal having a pixel density of 8 to 16 times the original number of pixels of the solid-state imaging device could be obtained.

In the above-described embodiment, the size of the light receiving portion in one pixel is set to be one pixel length in both the horizontal and vertical directions.
/ 4, but is not limited to this. In general, a solid-state imaging device in which the size of the aperture of the light receiving portion in one pixel is approximately 1 / n (n = 2, 3,...) Of the horizontal and vertical pixel intervals in both the horizontal and vertical directions, respectively. Use at least two. They are arranged on different light exit surfaces of an optical system such as an optical prism such that their relative positional relationship is shifted by 1 / n of the pixel interval in the horizontal and vertical directions in both the horizontal and vertical directions. Then, the relative positional relationship between the optical information from the subject and the light receiving section on each of the solid-state imaging devices is represented by at least two directions of horizontal and vertical directions, 1 / n or an integer of 1 / n of the pixel interval in that direction. Means for displacing at twice the distance, and integrating the optical information from the object and the image information captured at each position of the relative positional relationship between the light receiving unit on each of the solid-state imaging devices to obtain one high resolution What is necessary is just to provide for synthesizing the video signal.

Also, as a means for displacing the relative positional relationship between the optical information from the subject and the light receiving unit on each solid-state image sensor, the entire image pickup block is displaced using a piezoelectric actuator. However, the present invention is not limited to this. Instead, for example, an optical member having a birefringent action can be arranged in front of the optical prism, and the relative positional relationship can be changed by changing the inclination of the member with respect to the optical axis.

Although the description has been made using the output image of the X-ray image intensifier as the optical image incident on the optical prism, the present invention is not limited to this. However, when the wavelength band is limited to a certain wavelength band in the visible light region (in this example, only the green system) like the output image of the X-ray image intensifier, the influence of the chromatic aberration of the optical lens is reduced. Since it can be almost neglected, there is a feature that the high resolution effect can be exerted even in the periphery of the image.

In FIG. 1, the positions of the process circuits are as follows.
Although described as a subsequent stage of the high resolution processing circuit, the present invention is not limited to this position, and may be, for example, a preceding stage of the high resolution processing circuit.

As will be described below, the present invention is not limited to the above-described embodiment, and the scope of the present invention does not depart from the gist of the invention (for example, the number of CCD image pickup devices and the form of analog or digital output from the output terminal). Various modifications can be made.

As described in detail above, according to the present invention, 1
The size of the aperture of the light receiving portion in the pixel is approximately 1 / n of the horizontal and vertical pixel spacing in both the horizontal and vertical directions.
(N = 2, 3,...) At least 2
Use The relative position of each other is horizontal,
In the vertical direction, they are arranged on different light exit surfaces of an optical system such as an optical prism so as to be shifted by 1 / n of the pixel interval in the horizontal and vertical directions, respectively. Then, the relative positional relationship between the optical information from the subject and the light receiving unit on each of the solid-state imaging devices is determined in at least one of the horizontal and vertical directions by 1 / n or an integer of 1 / n of the pixel interval in that direction. Means for displacing at twice the distance, and integrating the optical information from the object and the image information captured at each position of the relative positional relationship between the light receiving unit on each of the solid-state imaging devices to obtain one high resolution Means for synthesizing a video signal.

[0026]

As described above, the present invention improves the resolution when the equivalent number of pixels is increased by devising the system, compared to the original resolution determined by the number of pixels of the solid-state imaging device. A solid-state imaging device that can solve the problem that the image quality is limited can be provided.

[Brief description of the drawings]

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

FIG. 2 is a view for explaining the size of a light receiving section in one pixel on the solid-state imaging device according to the embodiment of the present invention;

FIG. 3 is a diagram illustrating a relative positional relationship between two solid-state imaging devices according to the embodiment of the present invention;

FIG. 4 is a view for explaining a relative positional relationship between optical information from a subject and a prism according to the embodiment of the present invention.

[Explanation of symbols]

 11: X-ray image intensifier, 12: optical lens, 13: imaging block, 14: optical prism, 145, 146: light exit surface of optical prism, 15, 16: CCD imaging device, 7, 18: piezoelectric actuator, 19, 20: Preamplifier, 21, 22: A / D converter, 23, 24: Memory, 25: High resolution processing circuit, 26: Process circuit, 27: D / A converter, 28: Output terminal, 29 ... Actuator drive circuit, 30 ... CCD image sensor drive circuit, 31 ... Pulse generation circuit.

[Procedure amendment]

[Submission date] May 12, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (2)

[Claims] 1. A solid-state imaging device in which the size of an aperture of a light receiving portion in one pixel is substantially 1 / n (n = 2, 3,...) Of a pixel interval in the horizontal and vertical directions in both the horizontal and vertical directions. And at least two light emitting surfaces having different optical systems such as an optical prism so that their relative positional relationship is shifted by 1 / n of the pixel interval in the horizontal and vertical directions in both the horizontal and vertical directions. The relative positional relationship between the optical information from the subject and the light receiving unit on each of the solid-state imaging devices is at least one in the horizontal and vertical directions.
In one direction, 1 / n or 1 / n of the pixel interval in that direction
Means for displacing at an interval of an integral multiple of the optical information from the subject and the video information captured at each position of the relative positional relationship between the optical information from the subject and the light receiving unit on each of the solid-state imaging devices, A solid-state imaging device comprising means for synthesizing two high-resolution video signals. 2. An image conversion unit such as an X-ray image intensifier for converting image information from X-rays into a wavelength in a visible light region, and optical information in a visible light region output from the image conversion unit. The solid-state imaging device according to claim 1, wherein an image is taken by the solid-state imaging device.