JPS60125090A - Color solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve vertical resolution and oblique resolution by selecting transmitted color light for 2X4 unit areas so that all components constituting a luminance signal are obtained from each horizontal by a primary color filter during field reading operation. CONSTITUTION:The color filter 1 arranged on the optical path of a solid-state image pickup element is constituted as the primary color filter through which three primary color beams R, G, and B are transmitted. Further, 2X4 picture element areas are selected as a unit area and respective transmitted color light beams are so selected that a luminance signal is composed of only color components obtained from respective horizontal lines (n)', (n+1')... when fields are read. This color filter 1 has transmission areas G and R arrayed alternately for every picture element on off-numbered lines (n), (n+1)... before the field reading operation and also has transmission areas B and G arrayed alternately for every picture elements on even-numbered lines 263+n, 263+n+1.... Further, transmitted color light beams of even-numbered lines are out of phase with those of adjacent lines. Image pickup signals obtained by making a field read of new horizontal lines (n'), (263+n')... all contain R, G, and B and a desired luminance signal is generated without line interpolation.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a color solid-state imaging device using a solid-state imaging device such as a CCD.

Background Art and Problems In a single-chip color solid-state imaging device that uses a charge transfer device such as a COD as an imaging device, a color filter (1) that transmits primary color light as shown in Fig. 1 is used. There are cases.

This color filter (1) is configured to perform field accumulation mode readout (field readout) as described later, and is a (2×4) picture with 2 pixels in the horizontal direction and 4 pixels in the vertical direction. The elementary area is selected as the unit area,
On the odd lines in the odd and even fields, green G and red 11 transmission areas are arranged alternately, one pixel at a time, and similarly, on the even lines in each field, green G is arranged.
and 1rB transmission regions are arranged alternately by lki elements, and green G transmission regions are arranged in a checkerboard pattern.

Field readout is a successive readout method aimed at reducing afterimages, and refers to simultaneous readout of two lines as described below. Now, if the line numbers when performing normal interline scanning are determined as shown in the figure, in odd fields, line n, line n+263, (
n+x) line and (n+1)+26a line,...
. . . are output simultaneously, and the sum signal of each line is newly added to n' of the odd field.
line (=n+(n+263) line y), (n+t7 line y (= (n+1)+In+1)+263) line), etc., and in the even field, n+2632 line and n+1 line, (n+1)+263 line and n+2 line,
. . . so that each output of
+263 line (=(n+263)+(n+1) line), (n+17+z6a line y (=(n+1)+(2
63+(n+2)1 line), -, etc., is called field readout.

The color filter (1) configured in FIG. 1 when field reading is performed is equivalent to the color filter (1)' as shown in FIG.

Now, as is clear from FIGS. 1 and 2, in order to form the luminance signal Y using the color filter (1) in FIG. 1, it is necessary to use at least four lines of color information. Therefore, the vertical resolution of the luminance signal, especially the resolution in the diagonal direction (diagonal resolution) when the frequency is high in the horizontal direction, is significantly electrified.

OBJECTS OF THE INVENTION Accordingly, the present invention aims to improve vertical resolution and diagonal resolution in a color solid-state imaging device that performs field readout using primary color filters.

SUMMARY OF THE INVENTION Therefore, in the present invention, in a color solid-state imaging device that obtains an imaging signal by field readout, a color filter disposed on the optical path of the solid-state imaging device repeats two pixels in the horizontal direction. A (2×4) picture element area with four picture elements repeated in the vertical direction is selected as a unit area, and a color signal that constitutes a luminance signal is obtained only from signals obtained from each horizontal line when field readout is taken. As shown above, the primary color lights of )L, G, and H are selected as the transmitted color light of the (2×4) picture element area.

By doing so, it is possible to form a luminance signal on a line-by-line basis, so that deterioration in vertical resolution and diagonal resolution can be significantly improved.

EXAMPLE Next, an example of the present invention will be described in detail with reference to FIG. 3 and subsequent figures.

As mentioned above, the color filter (1) according to the present invention has an I
It is configured as a primary color filter that transmits each of t, G, and B as the transmitted light, and the same pixel area of , (n+1)',...
Each transmitted color light is selected so that the luminance signal is composed only of the color components obtained from .

FIG. 3 is an example of a color filter (1) that satisfies such conditions, in which odd-numbered lines n,
On n+1, . . . , G and R transmission regions are alternately arranged one picture element at a time, forming an even number line 263+n.

263+(n+1), . . . , the B and G transmission areas are similarly alternately arranged one picture element at a time. However, the transmitted color light of even-numbered lines is selected so that the adjacent lines have opposite phases.

If this color filter (1) is read out in the field, the fourth
This is equivalent to the color filter (1)' shown in the figure. As is clear from the diagram, the imaging signals on the new horizontal line "+263+n', . It is possible to form a luminance signal that

Therefore, deterioration in vertical resolution due to line interpolation can be prevented.

Also, from the odd lines n', (n+1)', ..., the luminance component of the interval (1) is obtained, Ct+YR=20+R+B, and the even lines 263+n', 263+
From ('')'+..., we can obtain the luminance components of Mz+2G = 20+R+B - (21).Since these luminance components are relatively close to the color component ratios that make up the luminance signal of the NTSC system, (1), (2)
The imaging signal expressed by the formula can be used as it is as a simple luminance signal.

Moreover, the color component composition ratio of the luminance signal obtained from the odd field is the same as the color component composition ratio of the luminance signal obtained from the even field, (1).

Even if the imaging signal of formula (2) is used as a brightness signal as it is, no brightness unevenness occurs.

FIG. 5 shows an example of a circuit system for forming a color video signal using the color filter (1) shown in FIG. 3.

In this imaging device (11), the imaging element al is C
A charge transfer device such as a CD is used, and signal readout is field readout as described above.

Therefore, an image signal Sin shown in equation (1) is obtained from the image sensor a11, and this signal is level-adjusted at qAGc (121), and then processed by the gamma correction circuit (131 and the Ronos filter for carrier trough). (It is supplied to the color encoder/(151 via the color encoder α9.
Easy brightness signal Y signal is used.

The imaging signal Sjn is further supplied to a pair of sampling and holding circuits Q81, (1'J) to detect even numbers 2y (n+1)', (n+3') in each field.
, −, 263+(n+1)′.

263+(n+3)', . . . imaging signals are sampled and point-sequential color signals are synchronized. Therefore,
The Sunnoring i9 pulses Pa and Pb supplied to the pair of sampling and holding circuits Q8) and (11) are two-phase/mother pulses with a period of 2 horizontal picture elements.
A color signal of Mz is obtained from one side, and a color signal of Mz is obtained from the other.

The image signal Sin is further passed through an IH (1-1 is a horizontal period delay element) to a pair of sampling and holding circuits (1-1 is a horizontal period).
2), (supplied to 2D, the point-sequential color signals are synchronized by the above-mentioned sampling signals Pa and pb supplied to these. Therefore, a color signal of cy is obtained from one side, and a color signal of cy is obtained from the other side. A Yy color signal is obtained.

The reason why the delay element α7) is provided is that it is not possible to form a pair of color difference signals (L-Y, B-Y) using only the color information of a single horizontal line, so line interpolation is used to
An r constant color difference signal is formed.

The four synchronized color signals are supplied to a matrix circuit to generate the synchronized primary color signals it, G, B.
is formed. Matrix circuit ray) is 1 as shown in the figure.
Consisting of 29 adders (29) and 3 subtractors (to) to (c), the first subtractor (c) obtains Yl-Cy=R-B, and the second subtractor ( 2η, 2G+Yffi+Cy-
Mz=4G is obtained, and in the third subtractor (c), Mz −
(It-B) = 2B is obtained, and in the adder (c), It-B+Mz=2R is obtained.

These primary color signals R-8 are each sent to the gamma correction circuit (to)
011 to the matrix circuit 0'lJ to form a pair of color difference signals) LY and BY. A pair of color difference signals 1 (-Y, 13-Y are respectively low-pass filters (
After being band-limited at (to) and (to), it is supplied to a color encoder (151) to form a power 2-video signal s'rv of the N1'SC system.

FIG. 6A, FIG. 7A, and FIG. 8A all show modified examples of the color filter according to the present invention. In this way, (2X4
), there are four combinations of primary color lights for obtaining a luminance signal from each new line during field readout, and any combination can be applied. 6th
Figure A, Figure 7A.

If each field is read using the color filter (1) shown in FIG. 8A, it becomes equivalent to the color filters (1r) shown in FIGS. 6B, 7B, and 8B.

As described in detail, according to the present invention, a primary color filter,
In order to obtain all the color components constituting the luminance signal from each horizontal line during field readout, we chose transmitted colored light in a unit area of (2 x 4), so that the vertical resolution, especially the diagonal resolution when the frequency is high in the horizontal direction, was reduced. can be significantly improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional primary color filter for explanation, FIG. 2 is a block diagram of a color filter equivalent to field readout of this primary color filter, and FIG. 3 is a color solid-state imaging device according to the present invention. A block diagram showing an example of a color filter used in the device, FIG. 4 is a block diagram of a color filter similar to that in FIG. 2, and FIG. A system diagram showing an example, and FIGS. 6 to 8 are configuration diagrams showing other examples of color filters that can be used in the present invention. (1) is a color filter, (111 is an image sensor, (241,
(3a is a matrix circuit, and a9 is a color encoder.

Claims (1)

[Claims] In a color solid-state imaging device that obtains 4F5 images by field readout, a color filter placed on the optical path of the solid-state imaging device has a color filter that repeats 2 pixels in the horizontal direction and 4 pixels in the vertical direction. A pixel area of (2×4) is selected as a unit area, and the above (2×4) pixel area is selected as a unit area, and the above (2
4) A color solid-state imaging device in which primary color light of R, (3, and H) is selected as the transmitted color light of the picture element region.