JPS5911308B2 - Color Kotai Satsuzou Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color solid-state imaging device using a solid-state imaging body such as a charge-coupled device (CCD), and particularly to a color solid-state imaging device that effectively eliminates aliasing distortion that occurs in the image output obtained from the solid-state imaging body. In addition, by obtaining a luminance signal having a level ratio of primary color signals close to the luminance component of the NTSC system over the entire band, it is possible to always obtain a high-quality image.

The apparatus of the present invention will be explained below with reference to the drawings.

First, a description will be given of a solid-state image sensor suitable for application to the present invention. In this example, a CCD that adopts a frame shift method is used, and this is performed in the horizontal and vertical directions as shown in Fig. 1. It has a plurality of picture elements 2 arranged respectively in
An imaging section IA onto which a desired subject image is projected; a light-shielded storage section IB having a configuration similar to that of the imaging section 4A;
Furthermore, it is comprised of a readout register 10 and an IC for reading out charges according to input light information of a subject image. 3 indicates an output terminal from which an imaging output is obtained.

Here, the input light information corresponding to the subject image to be imaged is sampled for each pixel and converted into an electrical signal, so unlike when a well-known vidicon tube is used,15 The image output is sampled as follows.

Therefore, if the sampling frequency is fc, by scanning each picture element in each horizontal section, an imaging output having a spectrum as shown in FIG. 2 can be obtained. In other words,
In addition to the modulation component j of the 20 degree brightness signal SY, a sideband component (AC component) sM is obtained in which the sampling frequency fc, which uses the sampling frequency as a carrier, is modulated by the modulation component SDC. In this case, if the band of the modulation component SDC is sufficiently taken, a part of the sideband component 1 overlaps with the high frequency component of the 25 modulation component SDC, and the shaded part becomes aliasing distortion. If you play back an image in this state, a flickering phenomenon will appear on the playback screen, which will degrade the image quality.

30 Specific means for preventing this image quality deterioration have already been proposed by the present applicant.

This goal was achieved by skillfully configuring three solid-state image sensors, and in particular, for the subject image projected onto the three solid-state image sensors, the 35 horizontal scanning directions of pixel 2 When the pitch in the direction corresponding to is τH, −τ
The subject images are projected while being sequentially shifted by H.

When using the subject image as a reference, as shown in FIG. 3, the first to third solid-state image pickup bodies 1R to 1B are sequentially -τ in the horizontal scanning direction.

All you have to do is shift and place it. In this way, positionally shifting by 1τo means that a phase difference of 1201 is given between the respective imaging outputs in terms of time, so that the imaging obtained from each solid-state imaging body 1R to 1B Output SR-SB
The middle sampling carrier W3 also has a phase difference of 120S. Therefore, the phase relationship of the carriers WO to W3 is as shown in FIG. 4, and when the levels of the imaging outputs SR-SB are matched and these imaging outputs SR-S are combined, the carrier W is obtained. -W8 is canceled out and becomes zero. That is, the sideband components become zero and no aliasing distortion occurs. A system diagram up to the synthesis of the imaging outputs SR-SB will be described using FIG. 5, which is also a system diagram of the main parts of the solid-state imaging device according to the present invention.

The object 11 is connected to each of the solid-state image pickup bodies 1R to 1BV through an optical lens system 12 and a spectroscopic system 14 for separating primary color light.
C is projected.

As shown in the figure, the spectroscopic system 14 has a pair of dichroic mirrors 14a and 14b, and the front dichroic mirror 14a is configured as an R-reflection type mirror that reflects only the red light R. Light R is the mirror 14c
is guided to the solid-state image pickup body 1R. The other mirror 14b is a mirror that reflects the blue light B, and in this way, the blue light B is separated into R-B, and is transmitted to each of the solid-state image pickup bodies 1R to 1B.
Desired color separation images are projected on each of the images.
Note that 14d indicates a mirror. Imaging output SR~ obtained from solid-state imaging bodies 1R~1B? are the level control circuits 15R to 1, respectively.
This adder 1 is supplied to the adder 16 via 5B.
The levels are adjusted by the above-mentioned level control circuits 15R to 15B so that the respective imaging output levels immediately before being supplied to the output terminals 6 coincide with each other.

In this way, sideband components are not included in the addition output obtained at the terminal 17 for the reason described above. In addition to the above-described configuration, the present invention is further configured such that the luminance signal itself, which is the addition output of the adder 16, becomes a luminance signal in the NTSC system.

Therefore, the spectral characteristics of the spectroscopic system 14 are not selected so that only the corresponding primary color signals are incident on each of the solid-state image sensors 1R to 1B, but are set to the spectral characteristics described below. First, the imaging output SR-SB obtained from each of the solid-state imaging bodies 1R to 1B is expressed by the following equation.

SR=RlR+GlG+BlB SG=R, R+G, G+B, B・・・・・・・・・・・・・・・
(1) SB: R, R+G3G+B,B Here, R-B is a primary color signal, and R, ~R,, b1-B, and g1-G are coefficients, respectively.

On the other hand, as is well known, the level ratio of the three primary color signals in the luminance signal of the NTSC system is R:G:B=0.3:0.59.
:0, 11... Since it is given by (2), in order to determine equation (1) so that equation (2) is satisfied, it is necessary to satisfy equation (3) below. .

Therefore, this equation (3) is changed to equation (4).

One of the conditions to satisfy the condition that the level of the imaging output SR-SB is constant in order to prevent the occurrence of aliasing distortion, and to configure it as an NTSC luminance signal is to have a green signal component that can be obtained with the highest level. The spectral characteristics of the spectroscopic system 14 may be selected so that a part of the blue signal component is included in the blue signal component obtained with the lowest level. The spectroscopic system 14 will be explained later, but if equation (4) is solved by incorporating these conditions, the following solution can be obtained. r1=0
．． 333r2=Rs=0 g2=0.333g, 20.223g120...B
3=0.110b1=B2=0 (6) In other words, the configuration is such that only the R and G primary color lights are incident on the first and second solid-state imaging bodies 1R and 1G, and the remaining solid-state imaging bodies The structure is such that in addition to the B primary color light, a part of the G primary color light is incident on the body 1B. It is something that can be achieved.

The level ratio of B and G is 0.11:0.223. Therefore, the imaging output SR-SB is expressed by the following equation. SR=0
．． 333R S0=0.333G・・・・・・(6)SB=0
．． 110B+0.223GSR=? =SB=0.333
:1 ......(7) As the spectroscopic system 14 for obtaining formula (6), the other dichroic mirror 14
The spectral characteristics of GO.b are such that the B component is completely reflected and the G component is reflected. 223 components to B component,
A reflectance of 0.110 is selected so as to double the reflectance.

Therefore, the spectral characteristics of the dichroic mirror 14b are as follows:
The spectral characteristics are such that a portion of the G component is also reflected. FIG. 6 shows still another example of the spectroscopic system 14 suitable for application to the present invention.

In this example, three prisms 20A to 20C are used, and in order to obtain red light R from the first prism 20A, a red light reflective dichroic layer is provided on the entire surface of the transmitting surface 21. 22 is deposited and formed using means such as vapor deposition. Similarly, in order to obtain the B component from the second prism 20B, the boundary surface between the second prism 20B and the third prism 20C, in this example, the surface 23 of the third prism 20C is A reflective dichroic layer 25 is deposited and a stripe filter 24 for reflecting the G component is provided in order to also obtain the G component from the second prism 20B side. That is, as shown in Figure 7. Stripe filter elements 24a having a width w such as A' are arranged in one direction with a predetermined pitch P.

The amount of reflected light of the G component can be determined by selecting the width w of the element 24a and the arrangement pitch P, so the stripes are arranged so that the ratio of the B component to the G component satisfies 0.110:0.223. This is what the filter 24 is designed for. Note that instead of providing the stripe filter 24, a third
Dichroic layer 2 formed on the prism 20C of
The spectral characteristics of No. 5 may be selected to be the same as the spectral characteristics of the dichroic mirror 14b used in FIG.

If the spectral characteristics of the spectroscopic system 14 are selected in this way, the imaging output from each solid-state imaging body 1R to 1B? ~If SB hooks are combined, the luminance signal SY is SY=0.333R+0.556G+0.110B...
(8) Therefore, the level ratio of the three primary color signals constituting the luminance signal SY is approximately equal to the level ratio of the luminance signal in the NTSC system.

Moreover, the band of the luminance signal that satisfies this NTSC system extends over the entire range. Incidentally, if the luminance signal is configured without using the configuration of the present invention, that is, if three solid-state image pickup bodies are provided corresponding to each of the R-B primary color lights and signal processing is performed, the details will be Although a detailed explanation will be omitted, out of the entire band of the luminance signal, only the low frequency range of about 1 to 1.5 MH2 is N.
It is not possible to approximate the luminance signal in the TSC method. Therefore, a reproduction error occurs in the luminance component and the color component. This is not the case with the present invention. Note that 30 indicates a matrix circuit, which is supplied with demodulated color signals obtained from the respective imaging outputs SR and SG of the first and second solid-state imaging bodies 1R and 1G, together with the above-mentioned luminance signal SY. For example, the desired color difference signals R-Y and G-Y can be obtained from the respective terminals 30a and 30b.

According to the above-described configuration of the present invention, it is possible to effectively remove aliasing distortion occurring during the imaging outputs SR to SB.
In addition to the feature that eliminates defects such as flickering on the screen even when images are projected, by appropriately selecting the spectral characteristics of the spectroscopic system 14, it is possible to obtain benefits by simply performing addition processing on the imaging outputs SR-SB. Since the brightness signal obtained has a value extremely close to the level ratio of the brightness signal in the NTSC system, the reproduced image is of good quality.

Furthermore, since the level relationship of the luminance signal in the NTSC system extends over the entire band, reproduction errors are completely eliminated. In addition, since the circuit configuration for obtaining this luminance signal is very simple, it has the practical benefit of realizing this type of color solid-state imaging device at low cost.

In addition, in the above-mentioned embodiment, the fifth spectroscopic system 14 is
Although the configuration example shown in FIG. 6 and FIG. 6 has been shown, it goes without saying that the spectroscopic system 14 can be constructed by appropriately combining dichroic mirrors, . . . , flames, etc.

In the above spectral characteristics, an example was explained in which a part of the G component was added to the B component to obtain the desired spectral characteristics. Of course, in order to make this the G component, the spectral characteristics of the front dichroic mirror 14a shown in FIG. 5 may be selected so as to reflect the G component as well.
In this case, the level ratio is closer to that of the NTSC system, so it has the effect of further improvement.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram showing an example of a solid-state image sensor;
The figure is a frequency spectrum diagram of the imaging output, Figure 3 is a relative arrangement diagram of the solid-state image sensor used in the device of the present invention, and Figure 4
The figure shows the positional relationship of sampling carriers, Figure 5 is a system diagram showing an example of a color solid-state imaging device according to the present invention, Figure 6 is a configuration diagram showing an example of a spectroscopic system, and Figure 7 is a part of it. FIG. 1R to 1B are solid-state image sensors, τ.

Claims (1)

[Claims] 1 It has three solid-state image pickup bodies, and these three solid-state image pickup bodies have a subject image separated into three-color light by a color separation optical system at a pitch of 1/3 in the direction corresponding to the horizontal scanning direction of the picture element. When the color imaging outputs obtained from each of the solid-state imaging bodies are added together via the level adjustment means to obtain a luminance signal, the level adjustment means adjusts the color imaging output. The level is adjusted so that the respective levels match, and the luminance signal is NTSC.
At least one of the three color lights from the color separation optical system is divided into two
A color solid-state imaging device, wherein the spectral characteristics of the color separation optical system are selected so as to include light of two primary colors.