JPS6238691A - Color solid-state image pickup element - Google Patents

Abstract

PURPOSE:To eliminate high brightness coloring due to generation of smear by adopting a building block of a filter element of 2 rows and 2 columns for color separation filter that signals obtained through the 1st and 2nd rows of filter elements are equal to each other at each column with respect to a specific light source. CONSTITUTION:In a color separation filter 11, 2-row, 2-column filter element 12 of Mg (magenta), G, Cy and Ye is used as a basic building block and the elements are arranged two-dimensionally. The color separation filter 11 is used and a light source 3,200 deg.K infrared cut filter (1.5mm thick) is used to pickup the image of an acromatic object. Thus, the spectral characteristic of the filter element 12 of each color is improved so that the signal through the Mg and the signal through the G are nearly equal and the signal obtained through the Cy and the signal through the Ye are nearly equal to each other. A color solid- state image pickup element is provided with the color separation filter 11 and the infrared cut filter (1.5mm thick). Thus, in taking a difference between signals obtained from the same column, the smear component is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color solid-state imaging device that can be used in a single-chip color solid-state camera.

BACKGROUND OF THE INVENTION In recent years, the image quality of single-chip color solid-state cameras has been significantly improved. In order to improve image quality, it is important to not only improve device characteristics but also consider improving colorization methods. Among these, a single-chip colorization method using a field accumulation mode is attracting attention, which has features such as reducing equivalent afterimages and flicker near the limit resolution. In particular, with color filters consisting of W (transparent), G (green), Cy (cyan), and Ye (yellow), image quality such as sensitivity and resolution was good (Masuda et al. Technical report, TEB
S69-1 (+981)).

4 to 6 regarding such a conventional color imaging device.
This will be explained using figures. FIG. 4 is an explanatory diagram of the configuration of a color filter of a conventional color image pickup device, FIG. 5 is a configuration diagram of a conventional color i-image device, and FIG. 6 is a configuration diagram of main parts of a conventional color image pickup device. In FIG. 5, 1 is a camera lens for condensing light onto an image sensor 2 with a color filter, 3 is a color separation circuit for obtaining color signals and luminance signals, 4 is a color encoder circuit for converting NTSC signals, and 5 1 is a vertical smear reduction circuit, 6 is an element drive circuit, and 7 is a logic circuit. In FIG. 6, 8 is a pixel and 9 is a signal vertical line.

Light that has passed through the camera lens 1 forms an image on an image sensor 2 with a color filter and is photoelectrically converted. Since the field storage mode is used as the signal readout mode, two rows are read out at the same time. That is, the element drive circuit 6 and the logic circuit 7 can obtain optical information that has passed through the W, G, Cy, and Ye color filter elements for each line as an electrical signal. Here, we will simply calculate the amount of those signals as W,...
G.S.

It is expressed as CyS + Y e s. The obtained signals are processed by the color separation circuit 3 into two color signals C shown by the following formulas 0 to 0.
The luminance signal Y is separated into a luminance signal Y, C2, and a luminance signal Y.

C+=(Ws+Cys) (Gs+Yes)=2B-
・・■C,= (Ws+Yes) −(Gs+Cys)
=2R-■Y=Ws+Gs+Cys+ Yes=
2 R+4 G+ 2 B- ■ Above ■ ~ (R, G of formula 3
, B are red, green, and blue signals, respectively. Furthermore, an NTSC signal can be obtained through the color encoder circuit 4. Here, when light with high light intensity enters through the camera lens 1, a smear signal is generated and the vertical signal line 9
come in. Since the amount of smear is proportional to the total amount of light irradiated in the vertical direction, the amount of readout of each signal is as follows.

Ws' = Ws + ΔWS + ΔGs - = ■ Yes'
=Yes+ΔYes+ΔG! /S”””■cyS'”
cys+Δcys+ΔY es−-■Gs' =Qs
10 ΔGs + Δw, - ΔWs of the force equation, to 80 +
ΔCyS+ ΔYes is the vertical smear component. Therefore, as shown below, the two color signals do not change, but the luminance signal changes.

C1==Ws'+Cy5'-GS'-Yes'
=Ws+Cys G6-Yes=2B...■ C2=Ws'10Yes'-GB'-Cys' =
Ws+Yes-GB-Cys=2R...■ Y=Ws'+Gs'+Cys'+Yes' =W
s+Gs+Cys+Yes+2Δ(Ws ten Gs ten Cys
+Yes)=2R+4G+2B+4Δ (R+20+B
)・・・・・・・・・[Phase] With this kind of output signal, one color difference signal R-Y, B-Y N
When obtaining a TSC signal, the smear signal affects the luminance signal Y, resulting in excessive coloring in a high-brightness object image. Therefore, the vertical smear reduction circuit 5 removes the smear component of the luminance signal Y to prevent the coloring phenomenon.

Problems to be Solved by the Invention However, in the conventional configuration as described above, a vertical smear reduction circuit is required to prevent coloring due to smear, which increases the camera price and increases the camera size. there were.

The present invention solves the above conventional problems, and aims to provide a color solid-state image sensor that can prevent coloring due to smear without using a vertical smear reduction circuit.

Means for Solving the Problems In order to solve the above problems, the color solid-state image sensing device of the present invention has two rows of filter elements that correspond to each pixel on a one-to-one basis.
Color separation filters are arranged two-dimensionally in a basic configuration of columns, and the basic configuration of the filter elements in two rows and two columns is divided into the first and second rows of each column for a certain light source. This configuration is such that the signal amounts obtained through the filter elements in each row are approximately equal to each other.

Effects According to the above configuration, the smear component is removed by taking the difference between signals obtained from the same column, so it is possible to obtain a color difference signal using it, and coloring due to smear can be avoided even without a vertical smear reduction circuit. will disappear.

Embodiment One embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 is an explanatory diagram of the configuration of a color filter of a color solid-state image sensor according to an embodiment of the present invention. The basic configuration is arranged in two dimensions.Using this color separation filter 11, infrared cut filter C5500 (thickness),
, 5mm) to image an achromatic subject,
The signal amount obtained through Mg and the signal amount obtained through G are approximately equal, and the signal amount obtained through Cy and the signal amount obtained through Ye are approximately equal.
The spectral characteristics of the filter elements 12 of each color are improved. The spectral characteristics are shown in FIG.

Signal processing using the color separation filter 11 will be explained with reference to FIGS. 1 and 3.

In FIG. 3, 13 is the color separation filter 1 of this embodiment.
1 and infrared cut filter C3500 (thickness 1.5mm)
This is a color solid-state image sensing device having the same structure as shown in FIG. 5 except that the vertical smear reduction circuit 5 is not provided. Since field storage mode is used, two rows are read out at the same time. Therefore, both row n of the first field and row n' of the second field contain Mg, Cy, G, Ye.
signal can be obtained. Below, the signal amount is M
gs, Cys, Gs.

Expressed as Yes. These signals are processed by the color separation circuit 3 into two color difference signals C, I C, and J shown below and a luminance signal Y.
′ and are separated.

C1' = (Mgs+Yes) - (Gs+Cys)
=2R-G-■C2' = (Mgs+Cys) -
(Gs+Yes) =28-a,,,,,,@)Y'
=Mgs+Gs+Cys+Yes=2R+3G+2B
---@Here, let us consider a case where an achromatic, high-brightness subject is imaged with a light source of 3200 mm. Since a smear component is generated, the amount of each signal is as follows.

Mgs'=Mgs+ΔMgs+ΔGs −−■Gs
'=Gs+AGs+ΔMg5-・-・@Cys'
=Cys+ΔCys+ΔY es −-(g)Yes'
=Yes+ΔYes+ΔCys..., ■However, the two color difference signals are as follows and are not affected by smear.

C,' = (Mgs+ΔMgs+ΔGs+Yes+Δ
Yes+ΔCys) (Gs+ΔGs+ΔMgs+C
ys + ΔCys + ΔYes) = Mgs + Yes - Gs
Cys-...@C2' = (Mgs+ΔMgs+
ΔGs+Cys+ΔCys+ΔYes)−(Gs+ΔG
s + ΔMgs + Yes + ΔYes + ΔCys) = Mg
s+Cys-Gs-yeB"""@further for the light source at 3200.

M gs -G s≠0... [phase] Cys-Y
es''; O...@, and there is no need to adjust the white balance using the luminance signal Y', so essentially the color difference signal is not affected by the luminance signal Y'.In other words, the vertical Even without a smear reduction circuit, coloring of the subject due to the generation of smear components does not occur.Furthermore, although the brightness was inferior to conventional color filters, the chromaticity was good.

According to this embodiment, the filter element 12 in the first row and first column is magenta, the filter element 12 in the first row and second column is cyan, the filter element 12 in the second row and first column is green, and the filter element 12 in the second row and first column is green. If the basic configuration is 2 rows and 2 columns in which the filter element 12 in the second row and column is yellow and a 3200mm light source is used, the amount of signal obtained through magenta is approximately equal to the amount of signal obtained through green, and the amount of signal obtained through cyan is approximately equal. Since the color separation filter 11 in which the amount of signal obtained is approximately equal to the amount of signal obtained through yellow is used, high brightness coloring of the subject due to generation of smear components does not occur even without a vertical smear reduction circuit.

Note that the filter element 12 of the one-color separation filter 11 is not limited to the configuration of the embodiment, and may have a configuration in which cy and Ye are replaced in FIG. 1, for example.

Effects of the Invention As described above, according to the present invention, the smear component is removed by taking the difference between signals obtained from the same column, so it is possible to obtain a color difference signal using this, and the vertical smear reduction circuit can be High brightness coloring due to smear generation can be eliminated without using it.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration of a color filter of a color solid-state image sensor according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the spectral characteristics of the color filter of the same color solid-state image sensor, and FIG. A configuration diagram of a color imaging device using an image pickup device, FIG. 4 is an explanatory diagram of the configuration of a color filter of a conventional color solid-state image pickup device, and FIG. 5 is a configuration diagram of a color imaging device using the same color solid-state image pickup device. FIG. 6 is a configuration diagram of a main part of a color filter of the same color solid-state image sensor. 11... Color separation filter, 12... Filter element, 13... Color solid-state image sensor agent Yoshihiro Morimoto 1st prisoner 77 --- Content Ij1@ 7411 ytz ---
Figure 2 Figure 4 Figure 5 Figure 6

Claims (1)

[Scope of Claims] 1. A color separation filter in which filter elements corresponding to each pixel on a one-to-one basis are arranged two-dimensionally in a basic configuration of 2 rows and 2 columns, and the filter elements in 2 rows and 2 columns; 1. A color solid-state image pickup device having a basic configuration such that the signal amounts obtained through filter elements in the first row and the second row of each column are approximately equal to each other for a certain light source. 2. The basic configuration of the filter elements is that the filter element in the 1st row and 1st column is magenta, the filter element in the 1st row and 2nd column is cyan, the filter element in the 2nd row and 1st column is green, and the filter element in the 2nd row and 2nd column is green. 2. The color solid-state image sensor according to claim 1, wherein the filter element is yellow. 3. The basic configuration of the filter elements is that the filter element in the 1st row and 1st column is magenta, the filter element in the 1st row and 2nd column is yellow,
2. The color solid-state image sensor according to claim 1, wherein the filter element in the second row and first column is green, and the filter element in the second row and second column is cyan.