JPH0417484A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve the luminance resolution and the color reproducibility by arranging an image pickup lens, a selective optical low pass filter, an infrared ray cut filter, a color filter and a solid-state image pickup means on a same optical axis and forming a repetitive pattern of N picture elements so as to have a picture element pattern repeated for a 4-line period. CONSTITUTION:After an undesired frequency component is eliminated from a light incident from an image pickup lens 1 at a selective optical low pass filter 2, an infrared ray component is eliminated from the result by an infrared ray cut filter 3. The signal is inputted to a solid-state image pickup means 5 via a color filter 4 having a picture element arrangement repeating a repetitive pattern of 4 picture elements for a period of 4-line, subjected to photoelectric conversion and outputted via a buffer means 6, and since a green signal band is spread and a broad band is ensured for the luminance signal band without being limited by the frequency band of red and blue signals, a solid-state image pickup device having high luminance resolution and excellent color reproducibility is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid-state imaging device such as a video camera having a light-to-electricity conversion means.

2. Description of the Related Art In recent years, solid-state imaging devices have been widely used in imaging devices such as video cameras. Solid-state imaging devices have various advantages, such as being small and lightweight, having uniform spatial resolution across the screen, and having low afterimages. However, as it is desired to further improve the resolution of EDTV, HDTV, etc., there are issues such as a decrease in sensitivity due to the increase in the number of pixels in solid-state imaging devices, and how to balance the increase in the number of pixels with the color signal band.

FIG. 4 is a block diagram of a conventional solid-state imaging device.

In FIG. 4, unnecessary high frequency components are removed from incident light that has passed through an imaging lens 51 by a crystal optical low-pass filter 52. Next, the infrared component is removed by the infrared cut filter 53. Further, the light passes through a color filter 54 and undergoes optical-to-electrical conversion at a solid-state imaging means 55. Solid-state imaging means 5
The output signal No. 5 is outputted via a bumper device 56. Here, an example of a conventional color filter is shown in FIG. Fifth
The figure is a configuration diagram of the color filter array viewed from above. In FIG. 5, the pixel G that outputs the green signal is arranged diagonally,
A Bayer arrangement is shown in which a pixel R that outputs a red signal and a pixel B that outputs a blue signal are arranged between a pixel G that outputs a green signal. The Bayer arrangement has the advantage of good color reproducibility because each of the colors red, blue, and green can be directly extracted through the primary color filter of each pixel.

Problems to be Solved by the Invention However, the intervals between the same color filters are every other pixel, as shown in the pixel interval of the pixels that output red signals in Fig. 6, and optical low-pass filters are used to remove false signals. The band of the filter has to be narrowed, and the luminance signal band is also narrowed at the same time. Furthermore, when odd lines are read out in the first field and even lines are read out in the second field, there is a problem in that color separation occurs in the moving image because the red and green signals are aligned in the two-field sequence. FIG. 6 is a frequency characteristic diagram showing bands on a two-dimensional frequency axis of green, red, and blue signals obtained from a solid-state imaging device using a conventional Bayer arrangement. f, Iz are horizontal Nyquist frequencies,
rvz is the vertical Nyquist frequency. As shown in FIG. 6, the bands of green, red, and blue signals have horizontal frequencies fi1. All 1
．． There was a problem in that the luminance resolution was limited to the wave number fv+ and dominated by the green signal band, and could not obtain sufficient luminance resolution.

Means for Solving the Problems In order to solve the above problems, the solid-state imaging device of the present invention includes:
An imaging lens, a selective optical low-pass filter, an infrared cut filter, a color filter, and a solid-state imaging means are arranged on the same optical axis, and the light incident through the imaging lens is filtered by the selective optical low-pass filter. After unnecessary high frequency components are removed, the infrared component is removed by an infrared cut filter, and the signal is further inputted to a solid-state imaging means via a color filter, subjected to optical/electrical conversion, and outputted as an electrical signal at the output terminal. It is configured to

Further, the color filter of the solid-state imaging device according to the present invention has a repeating pattern of N pixels as the pixel arrangement of the first line, and a repeating pattern of N pixels that is the same as the pixel arrangement of the first line as the pixel arrangement of the second line. The pixel array of the third line has a repeating pattern of N pixels different from the first line, and the pixel array of the fourth line has a repeating pattern of N pixels.
It has a repeating pattern of N pixels, which is the same as the pixel arrangement of a line, and is configured to have a pixel arrangement that repeats every four lines.

Function: The solid-state imaging device of the present invention has the above-described configuration, thereby providing a lifting means with high luminance resolution and good brown color reproducibility.

Embodiment Hereinafter, one embodiment of a solid-state imaging device according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a solid-state imaging device of the present invention. The light that has entered through the imaging lens 1 is filtered by a selective optical low-pass filter 2 where only specific optical frequency components are selectively low-pass filtered to remove unnecessary frequency components, and then filtered by an infrared cut filter 3. Infrared components are removed. Next, the light that has passed through the infrared cut filter 3 is input to the solid-state imaging means 5 via the color filter 4, undergoes optical-to-electrical conversion, and is output via the buffer means 6. FIG. 2(A) shows the pixel arrangement of the color filter 5 in the solid-state imaging device shown in FIG. In order to complete the red, green, and green signals in each field, the pixel array of the first line is red, green, and green.
It has a repeating pattern of 4 pixels of blue and green, the pixel arrangement of the second line has the same repeating pattern of 4 pixels as the pixel arrangement of the first line, and the pixel arrangement of the third line is different from the first line. Differently, it has a repeating pattern of 4 pixels of green, red, green, and blue, and has a repeating pattern of 4 pixels that is the same as the pixel arrangement of the 3rd line as the pixel arrangement of the 4th line, and repeats at a 4-line period. It is configured to have an array.

However, if this continues, it will not be possible to widen the green signal band.

FIGS. 2(B), 2(C), and 2(D) are configuration diagrams of an example of the phase filter 2 used in the solid-state imaging device according to the present invention, viewed from the side. The phase filter 2 shown in FIG. 2 is made of resin or the like having two-dimensional irregularities, and light passes through it from the direction shown by the arrow in FIG. 2(B). As a result, diffraction occurs and the subject image appearing on the solid-state imaging means 5 is subjected to spatial low-pass filter processing. Furthermore, spatial low-pass filter processing using a phase filter has wavelength dependence, and can be configured to selectively block only specific wavelength components, for example, only red and blue signal components, while allowing green signal components to pass. . Therefore, by using the phase filter 2, only the green signal and the red signal can be selectively low-pass filtered, and the green signal band contributing to the luminance signal can be made sufficiently wide. Although FIG. 2(B) shows a square wave shape, in order to widen the frequency characteristic of the light that has passed through the phase filter 2, it is necessary to use a surfing wave shape as shown in FIG. 2(C), or the shape shown in FIG. A trapezoidal wave-like surface shape as shown in (D) is desirable.

FIG. 3 is a two-dimensional frequency characteristic diagram showing the bands of the green signal, red signal, and blue signal obtained in the present invention. The passbands of the blue signal, red signal, and low frequency component of the green signal by phase filter 2 are the areas surrounded by squares in Figure 3, and the entire passband of the green signal is the origin and (fHx, O).
, (0, fvz). Therefore, the frequency bands of green and red lights are
Similar to Fig. 6, horizontal frequency f, ll + vertical frequency fv
However, since the green signal band has the horizontal frequency f Hl and the vertical frequency fv□, the luminance signal band is not limited to the frequency bands of the red signal and the green signal, and a wide band can be secured.

In the embodiment of the present invention, an example of 4WM elements is shown as the repetition of N pixels, but the value of N may be an integer of 1 or more.

Effects of the Invention As described above, according to the solid-state imaging device of the present invention, a solid-state imaging device having high luminance resolution and good color reproducibility can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the solid-state imaging device of the present invention, and FIG.
Figure (A) is a configuration diagram showing an example of the pixel arrangement of the color filter used in the solid-state imaging device according to the present invention, and Figure 2 (B)
, (C), and (D) are side views of examples of phase filters used in the solid-state imaging device of the present invention, and Figure 3 is a two-dimensional diagram showing the bands of green, red, and blue signals obtained in the present invention. Frequency characteristic diagram, Figure 4 is a professional diagram of a conventional solid-state imaging device, Figure 5 is a configuration diagram showing a conventional color filter arrangement, and Figure 6 is a diagram showing green and red signals obtained in a conventional solid-state imaging device. FIG. 2 is a two-dimensional frequency characteristic diagram showing bands of a signal and a green signal. 1... Imaging lens, 2... Selective optical low pass filter, 3... Infrared cut filter, 4... Color filter, 5... . . . Solid-state imaging means, 6 . . . Buffer device. Name of agent Patent attorney Shigetaka Awano and one other person

Claims (3)

[Claims] (1) An imaging lens, a selective optical low-pass filter,
An infrared cut filter, a color filter, and a solid-state imaging means are arranged on the same optical axis, and the light that enters through the imaging lens is removed from unnecessary high-frequency components by a selective optical low-pass filter, and then the red The infrared component is removed by an outer cut filter, and the removed light is input to the solid-state imaging means via the color filter, undergoes optical-to-electrical conversion, and is output as an electrical signal to an output terminal. A solid-state imaging device characterized by: (2) The color filter has a repeating pattern of N pixels as the pixel arrangement of the first line, a repeating pattern of N pixels that is the same as the pixel arrangement of the first line as the pixel arrangement of the second line, and a repeating pattern of N pixels as the pixel arrangement of the second line. having a repeating pattern of N pixels different from the first line as a three-line pixel array;
The solid-state imaging device according to claim 1, wherein the pixel array of the fourth line has a repeating pattern of N pixels that is the same as the pixel array of the third line, and has a pixel array that repeats at a period of four lines. (3) The pixel array of the first line has a repeating pattern of N pixels, the pixel array of the second line has the same repeating pattern of N pixels as the pixel array of the first line, and the pixels of the third line A pixel array having a repeating pattern of N pixels that is different from the first line as an array, having a repeating pattern of N pixels that is the same as the pixel array of the third line as a pixel array of the fourth line, and repeating at a four-line period. Color filter with.