JPS6070887A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To double the number of vertical picture elements and to improve the horizontal resolution without losing aperture rate by arranging two solid-state image pickup elements having identical picture element arrangement and identical kind of color filter at a prescribed pitch. CONSTITUTION:The two solid-state image pickup elements 1, 2 having the identical picture element arrangement and identical kind of color filter are provided. The picture element of the other element 2 is arranged so as to be shifted spatially by a half picture element pitch in both vertical and horizontal directions to the picture element of one image pickup element 1. Interlacing is conducted for the read of signals by reading sequentially picture element columns S11, S21 on one line at the 1st H (horizontal period) of the field A and S12, S22 at the 2nd H. Thus, the number of vertical picture elements is doubled and also the horizontal resolution is improved without increasing the horizontal read frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a solid-state imaging device, and particularly to an imaging method suitable for increasing the number of vertical scanning lines.

[Background of the invention]

With recent improvements in semiconductor manufacturing technology, MOS and CCD types have been developed for use in NTSC consumer color video cameras.
MOS type solid-state image sensing devices have already been put into practical use for PAL and SECAM type consumer color video cameras. Advantages of this solid-state image sensor include small size, light weight, and high reliability; however, one disadvantage is that the aperture ratio of the light-receiving section is greatly affected by manufacturing process technology. In particular, if the number of vertical scanning lines is increased (from 525 lines to 1,000 lines) due to the recent trend of improving image quality, this will result in a significant decrease in the aperture ratio.

Additionally, the horizontal readout frequency will increase significantly.

I will explain to Tsuko using an example.

FIG. 1 shows an MO8 type image sensor. In the figure, 1 is a picture element, 2 is a vertical gate line, 3 is a vertical signal line 4 is a vertical MO
There are 8 switches. The picture element has four color filters, transparent (
W), yellow (Ye), cyan (CyX, green (G)) are each formed on-chip.

Signal reading is performed as follows: 1) During the horizontal retrace period, the photoelectrically converted signal of the pixel in the row selected by the vertical gate line is
It is transferred to the vertical signal line through the OS switch. 2) Horizontal shift register during horizontal scanning period.

The data are read out sequentially by the star. This process is taken.

As can be seen from Figure 1, there is a region (hereinafter referred to as a non-photosensitive area) that does not contribute to photoelectric conversion, such as vertical gate lines and horizontal signal lines, corresponding to one pixel, and the area of one pixel is Sa, 1 If the volume of the non-photosensitive area corresponding to the picture element is Sb, the aperture ratio is 8a/C
3ffi+Sb).

Now, for the sake of simplicity, let's assume that we double the number of picture elements in the vertical direction, and correspondingly double the number of picture elements in the horizontal direction.
Light-receiving area (Sa+5b)XN (N is the total number of picture elements) Under certain conditions, since N is multiplied by 4, (Sa-1-8b) needs to be set as S.

However, in order to reduce the amount of Sb to 4, the layout pattern must be miniaturized, which is subject to restrictions on manufacturing process technology. Originally, sb was made to be as small as possible, and now only by applying technology that can make the pattern even finer! 1lSb does not become smaller, and in the end S
If only a is made smaller, the aperture ratio will decrease.

However, simply increasing the light-receiving area will increase the chip area of the device and degrade yield.

On the other hand, since the number of picture elements has quadrupled on the gold side, the horizontal readout frequency has quadrupled. The horizontal readout frequency of the MO8 type image sensor shown in Fig. 1 is the Z modulus, and when multiplied by 4, it becomes approximately 30MHz, so the operating limit frequency of the horizontal shift register and the circuit that drives it must be adjusted to match this frequency. only have to be secured.

[Purpose of the invention]

An object of the present invention is to provide a solid-state imaging device that doubles the number of vertical picture elements without impairing the aperture ratio and improves the horizontal resolution without increasing the horizontal readout frequency using conventional semiconductor process technology.

[Summary of the invention]

Two solid-state image sensors (hereinafter referred to as sensor 1 and sensor 2) having the same pixel arrangement and the same type of color filter are arranged such that the pixel of sensor 2 is spatially perpendicular to the pixel of sensor 1, and
Sensor 1 is arranged so as to be shifted by half a pixel pitch in both horizontal directions.
, 2, a luminance signal Y and a color signal R are obtained from each row of picture elements.
(red) and B (blue). This doubles the number of picture elements in the vertical direction and further improves the resolution in the horizontal direction. At this time, the horizontal readout frequency is twice that of the conventional one, but this is not due to shifting the sensor 1 and 2 by half a pixel pitch in the horizontal direction to improve the horizontal resolution, but by increasing the number of pixels in the vertical direction. This is due to the fact that it has doubled.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 6.

FIG. 2 shows the same MO8 type image sensor as in FIG. 1, but the vertical gate lines and the like are omitted. In the figure, squares indicate pixel arrangement of sensor 1, circles indicate pixel arrangement of sensor 2, and signals W, ye, and Cy corresponding to three types of color filters w, ye, and cy are shown.
are read out using separate signal lines.

In the figure, a subscript is added to W+ Yer Cy, which corresponds to sensors 1 and 2.

Also, Smn is expressed as m (m=1 Or 2
) is the signal in the first row. To read the signal, set 811 and 821 in the 1st H (horizontal period) of the A field, and in the 2nd H
Read out 812 and 822 in the 3rd H, 813 and 823 in the 3rd H, and so on, 812 and SK+ in the 1st H of the B field, StS and 822 in the 2nd H, and 8 in the 31st-f.
14 and 823 are sequentially read and incremented. The luminance signal Y and the color signals R and B are Y=W+ye+Cy=2r+5g+2bR=w −
cy = r B = w - ye = = b. Here, 19g and b are red, green, and green signals, respectively.

FIG. 3 shows a camera block diagram. 7.8 in the figure are the sensors 1 and 2 of FIG. 2, respectively, which supply the same drive pulse 10 to the drive circuit 9.

Further, 5 is an optical lens, 6 is an optical system composed of a half mirror, etc., and 5 and 6 form the same image on the sensor 1.2. Note that 11 is a delay circuit, 12 to 15 are adders, and 16 and 17 are subtracters. As shown in FIG. 2, the pixels of the sensors 1 and 2 are arranged with a half pixel pitch shifted in the horizontal direction, but the same drive pulse 10 is supplied to the sensors 1 and 2. For this purpose, the signal W21 Yez r CYt read from the sensor 2 is transmitted to the delay circuit 11.
Delay by half a pixel pitch with w2. y” and sensor t
The signals w, ye, cy, read from tCy2 1 are made to correspond to the spatial arrangement, and then the signals from the sensor 12 are added in adders 12 to 14 to create w, ye, and Cy. This W.

Adder 15.ye, cy. The subtracters 16 and 17 perform addition and subtraction according to the above formula to produce a luminance signal Y and color signals R and B. After this, a video signal is obtained by a normal process signal processing circuit and an encoder circuit.

Incidentally, if the readout of sensor 2 and the readout of sensor 1 are performed in advance with a shift of υ half a pixel pitch, the delay circuit 11 becomes unnecessary. At this time, among the drive pulses to the sensor 1.2, only the pulse for driving the horizontal shift register is different.

Further, the color filters shown in FIG. 2 are not limited to W, Ye, and Cy, but may be fcG, Ye, and Cy by replacing W with G, for example.

In this case, the luminance signal Y and color signals R and B are obtained by the following calculations in the same manner as in the block of FIG.

Y = g+ye cy = r+3 g+bR2ye
-g = r B = cy-g = b [Effects of the Invention] According to the present invention, the number of vertical picture elements is doubled without impairing the aperture ratio using the semiconductor process technology used in conventional solid-state image sensors, and the number of vertical pixels is Resolution can be improved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a conventional solid-state imaging device, FIG. 2 is a layout diagram of a solid-state imaging device according to an embodiment of the present invention, and FIG. 3 is a block diagram of a solid-state imaging device according to the same embodiment. 7...First sensor, 8...Second sensor, 12-15...Adder, 16.17...Subtractor. ”+ () Representative Patent Attorney Akira Takahashi Figure 1; Figure f2

Claims (1)

[Claims] 1. An imaging unit consisting of a solid-state image sensor in which photosensitive elements having different spectral characteristics are periodically arranged, and signal processing that creates a color video signal from signals obtained by sequentially reading out the charges accumulated in the photosensitive elements of the solid-state image sensor. In the solid-state imaging device having a section, the imaging section is composed of two equivalent solid-state imaging devices in which photosensitive elements having three types of spectral characteristics are arranged periodically, and the photosensitive element of the first solid-state imaging device and the photosensitive elements of the second solid-state image sensor are arranged so as to be shifted by half a pitch from each other in the vertical and horizontal directions, and the photosensitive elements in one row in the horizontal direction of the first solid-state image sensor and the photosensitive elements in the vertical direction A solid-state imaging device characterized in that charges accumulated in one horizontal row of photosensitive elements of a second solid-state imaging device adjacent to the second solid-state imaging device are read simultaneously and sequentially during one horizontal scanning period.