JPS6037887A - Solid state image pickup device - Google Patents

Abstract

PURPOSE:To obtain output video of high resolution keeping compatibility with a video signal system currently used by making lateral mechanical size of an image pickup face relatively longer than reproduced picture and arranging picture elements having larger number of picture elements in lateral direction in an image pickup cell array corresponding to the image pickup face. CONSTITUTION:Ratio of length to breadth of mechanical size of image pickup picture face of an image pickup cell array 10 is made longer sideways than reproduced picture and the number of picture elements is made larger is H direction. The image of a subject formed on the array 10 is elongated in H direction by a cylindrical face lens 16 and formed over full length of the array 10. When the picture element signals taken in this way is read out, image pickup cells are driven at vertical and horizontal scanning speed used in the standard television signal form. Accordingly, when video signals outputted from a video circuit 52 to a terminal 62 are reproduced by a video reproducing device of standard television system, a picture of a high resoluting power including 700 picture elements in H direction in the case of normal mechanical size ratio of length to breadth for instance 3:4 is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a solid-state imaging device, in particular, a charge-coupled device (CCN) or an MO9 type imaging device, and is capable of forming high-resolution, high-quality images. The present invention relates to solid-state imaging devices.

The number of imaging cells, that is, pixels included in the imaging cell array of one screen of a solid-state imaging device depends on the microfabrication technology used in semiconductor manufacturing to manufacture the imaging device. At the current state of the art, the limit would be, for example, about 500 pixels x 400 scanning lines, that is, about 200,000 pixels.

These limitations are due to the fact that in an imaging system compatible with current television video signal systems, the number of scanning lines on the screen and the mechanical dimension ratio of vertical and horizontal dimensions are restricted, and it is impossible to reduce the size of the unit imaging cell below a certain level. Semiconductor chip 1 t=
This is because there is a limit due to the incident light sensitivity of the cell, and there is a limit to increasing the size of the semiconductor chip constituting the imaging device beyond a certain level due to manufacturing yield.

On the other hand, the quality of images obtained from conventional solid-state imaging devices is not necessarily satisfactory. In a solid-state imaging device that outputs a video signal of a signal format compatible with current television video signals, the vertical resolution of one screen, that is, the number of scanning lines, is required to be, for example, about 480 to 525 pixels.

However, regarding the horizontal resolution, the above-mentioned approximately 500 pixels is insufficient because human vision is more sensitive to the horizontal direction than to the vertical direction.

Further, the size of the display screen of a television image display device is usually set to have a mechanical dimension ratio of about 3:4. Therefore, in a solid-state imaging device that is compatible with the television video signal system, since the number of scanning lines is limited as described above, it is possible to achieve the same density of pixels in the horizontal direction as in the vertical direction with the same microfabrication precision using these mechanical dimensions. In order to form an image pickup cell in the image sensor, the number of pixels is itself limited. Therefore, it is possible to arrange more pixels in the horizontal direction by increasing the precision of microfabrication in the horizontal direction of the screen, but in this way, the optical aperture area for the incident light of each imaging cell becomes smaller.
The incident light sensitivity will decrease.

Dan-Issuke The present invention overcomes these drawbacks of the prior art.

The purpose of the present invention is to provide a solid-state imaging device that can obtain high-resolution output video while maintaining compatibility with current video signal systems.

According to the present invention, in a solid-state imaging device having an imaging cell array in which a plurality of imaging cells are arranged two-dimensionally to form an imaging surface, the imaging surface has a horizontal mechanical The imaging cell array has a generally rectangular shape with a relatively long surface dimension, and the imaging cell array has a large number of pixels arranged in the horizontal direction corresponding to the relative length in the horizontal direction of the imaging surface. .

Further, according to the present invention, the imaging device includes an imaging optical system that forms a subject image on an imaging cell array, and a drive circuit that drives the imaging cell array in a rask scan to read out a video signal, and the imaging optical system includes: , a deforming means for deforming the subject image to substantially match the shape of the imaging surface, and the driving circuit is configured to form a reproduction screen with regular mechanical dimensions.
Rask scan the imaging cell array.

Next, embodiments of the solid-state imaging device according to the present invention will be described in detail with reference to accompanying drawings.

As shown in FIG. 1(A), in the solid-state imaging device according to the present invention, the two-dimensional imaging cell array IO of the solid-state imaging device has the following features compared to the conventional one.

First, although the array 10 has a generally rectangular shape as a whole, there is a large difference in mechanical dimensions in the vertical and horizontal directions of the imaging screen. In a conventional imaging device, for example, as shown in FIG. 1(,B), the ratio of the mechanical dimension in the horizontal scanning direction H to the mechanical dimension in the vertical scanning direction V of the imaging cell array IOa is large enough for playback on a television video display device. Virtually equivalent to that of the screen. In other words, the ratio is about 3 to 4. On the other hand, the array 1o of imaging devices used in the apparatus of the present invention is relatively long in the horizontal direction, that is, in the H direction, compared to the playback screen. - For example, as shown in FIG. 1(A), the ratio is approximately 1:2. The length in the H direction, that is, the width of the screen, is approximately twice as long as the length in the ■ direction, that is, the height of the screen.

Second, the number of pixels in the horizontal direction is larger than that of the conventional 7-ray IOa. In the example shown in FIG. 5A, there are 400 scanning lines in the {circle around (2)} direction, which is the same as the conventional one in consideration of compatibility with the standard television signal system. On the other hand, in this example, 700 pixels are arranged in the H direction. The imaging cell array in the H direction is advantageously formed with a fine force that is substantially the same or comparable to that in the (1) direction. The reason for increasing the number of cells in the H direction is that the resolution in the H direction can be improved by the imaging and readout methods described below.
This is to make them second.

Note that the double numerical example is merely an example for understanding the present invention, and there is no restriction on taking other numerical values. For example, the number of scanning lines in the ■ direction may be any other feasible value such as 480 trees, 525 trees, 625 trees, 819 trees, etc. Also, what is the number of pixels in the H direction? 50
pixel, 800 pixels, 1000 pixels, or any other feasible number.

Referring to FIG. 2, such a two-dimensional imaging array 10
An embodiment of a solid-state imaging device having 10 solid-state imaging devices 12 is shown above. The imaging device 12 may be any type of solid-state imaging device, such as a CCD, a MOS imaging device, or a priming transfer device (CPD).
It has the characteristics described above with respect to FIG.

A cylindrical lens 16 and a normal imaging lens (mask lens) 18 are arranged in this order in front of the optical axis, which is an axis 14 passing through the center of the imaging cell array lO and perpendicular thereto, and forming an imaging optical system 20. is formed. The imaging lens 18 may be a normal spherical lens, and forms an object image on the array 10 through the cylindrical lens 16.

As can be seen from FIG. 3, in which the imaging optical system 20 is viewed from above in FIG.
As shown by the dotted line 22, it does not span the entire width of the imaging array IO. As can be seen from these figures, the cylindrical lens 16 has two cylindrical surfaces 17 as its main surfaces, and the cylindrical surfaces 1
The generatrix 7 is arranged so as to be substantially parallel to the {circle around (2)} direction. As a result, the incident light beam is expanded only in the H direction, and the subject image is deformed to substantially match the shape of the imaging surface of the imaging cell array IO. That is, as shown by the solid line 24 in FIG. 3, the shape and position of the lens 16 are set so that the incident light beam spreads in the H direction and reaches the entire width of the array 10. It goes without saying that the light beam spreads over the entire height of the array 10 in the {circle around (2)} direction.

With such a configuration of the optical system 20, the imaging lens 18
The image of the subject captured by is focused on the horizontally long array lO.

FIG. 2 shows a clock generation circuit 50 for driving such a solid-state imaging device 12, and a clock generation circuit 50 for driving such a solid-state imaging device 12.
Also shown is a video circuit 52 that converts the pixel signals output from the video signal into a video signal in a standard format such as the NTSC standard color television system.

For example, when the imaging device 12 is a COD, the clock generation circuit 50 supplies a vertical transfer lock Vlll:LK and a horizontal transfer lock HCLK to the imaging device 12 via connection lines 54 and 56, respectively. Furthermore, a synchronizing signal 5YNG is supplied to the video circuit 52 through a connection line 58. The imaging device 12 uses these clocks V C
A pixel signal is extracted from each imaging cell in response to LK and HCLK, and is input to the video circuit 52 through an output line 60. The video circuit 52 converts this pixel signal into a video signal in a predetermined television signal format in response to the signal 5CNC, and outputs the video signal to a video signal output terminal 62.

What is important here is that the vertical transfer lock VCLK may have the same frequency as the conventional one, but the horizontal transfer lock HCLK has a higher frequency than the conventional one. For example, if we take the pixel arrangement in FIG. 1(A) as an example, 400 scanning lines are arranged in the H direction. Therefore, vertical transfer lock VGLK
may have a frequency that vertically scans 525 scanning lines per frame including the vertical blanking period. In the interlaced scanning method of two fields per frame, the vertical transfer lock VGLK has a frequency of 15.75 kHz. For IcLK (horizontal transfer lock), horizontal scanning period (IH)
Since pixel signals of 700 pixels are transferred during the period, a multiphase clock having a frequency of about 13.3 MHz is output during the effective horizontal scanning period excluding the horizontal retrace period.

To summarize, in this device, the aspect ratio of the mechanical dimensions of the imaging screen of the imaging cell array 10 is larger than that of the reproduction screen, that is, it is configured to be horizontally long, and the number of pixels in the H direction is large. The image of the subject formed on the array 10 is stretched in the H direction by the cylindrical lens 16 and is formed across the entire width of the array 10. In other words, the subject image is formed on the entire imaging screen of the array 10. When reading out pixel signals captured in this manner, each imaging cell is driven at the vertical and horizontal scanning speeds used in standard television signal formats. That is, the vertical scanning frequency is the same clock frequency as the conventional one, and the horizontal scanning frequency is set to a high clock frequency corresponding to the number of pixels included in the I] force direction.

Therefore, when the video signal outputted from the video circuit 52 to the terminal 62 is played back on a standard television video playback device, as shown in FIG. 4, a high-resolution screen 70 including 700 pixels in the H direction is reproduced.

Although an example in which the present invention is applied to COD has been described,
It goes without saying that the present invention is not limited to this, but is widely applicable to solid-state imaging devices using other methods such as MOS type solid-state imaging devices and CPD.

Since the solid-state imaging device according to the present invention is configured as described above, while maintaining compatibility with the current video signal system,
It is possible to obtain output images with high resolution. Moreover, although the resolution of imaging cell arrays in solid-state imaging devices has improved in the horizontal direction, it is possible to manufacture them with substantially the same or similar microfabrication precision in the horizontal direction as in the vertical direction. Therefore, since the optical aperture area of each imaging cell is the same or comparable to that of conventional imaging devices, the same level of incident light sensitivity can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an imaging cell array of a solid-state imaging device for explaining the present invention in detail, FIG. 2 is a perspective block diagram showing an embodiment of the solid-state imaging device according to the invention, and FIG. FIG. 4 is an explanatory diagram showing the optical system of the apparatus shown in FIG. 2 viewed from above FIG. 2, and FIG. - Of the essential ingredients. 10, Imaging cell array 12, Solid-state imaging device 1B, Cylindrical lens 18, Imaging lens 20, Imaging optical system 50, Clock generation circuit 70, Reproduction screen

Claims (1)

[Claims] (1) In a solid-state imaging device having an imaging cell array in which a plurality of imaging cells are arranged two-dimensionally to form an imaging surface, the imaging surface has a lateral mechanical dimension compared to a reproduction screen. is relatively long and has an almost rectangular shape as a whole, and the imaging cell array has imaging cells arranged in a horizontal direction corresponding to the relative length of the imaging surface in the horizontal direction. A solid-state imaging device characterized by: 2. A solid-state imaging device according to claim 1, wherein the imaging cell array is formed with substantially the same fine processing precision in both the vertical and horizontal directions of the imaging surface. 3. An imaging surface chair in which a plurality of imaging cells are arranged two-dimensionally; an imaging optical system that forms a subject image on the imaging cell array; and a drive circuit that drives the solid-state imaging device in a rask scan manner to read out video signals. In the solid-state imaging device, the imaging surface has an overall approximately rectangular shape with a relatively long mechanical dimension in the lateral direction compared to the reproduction screen, and the imaging cell array extends in the lateral direction of the imaging surface. Imaging cells having a larger number of pixels are arranged in the horizontal direction corresponding to the relatively longer length, and the imaging optical system includes a deforming means for deforming the subject image so as to substantially match the shape of the imaging surface. A solid-state imaging device, wherein the drive circuit scans the imaging cell array in a raster manner so as to form the reproduction screen with regular mechanical dimensions. 4. The apparatus according to claim 3, including a cylindrical surface lens disposed in , wherein the generatrix of the cylindrical surface is arranged substantially parallel to the longitudinal direction of the imaging surface. A solid-state imaging device.