JPS63169890A - Color image pickup device - Google Patents

Abstract

PURPOSE:To double the luminance signal band by tilting the lengthwise direction of each filter streak of a stripe filter toward a scanning line and setting the basic wave component signal within the luminance signal band. CONSTITUTION:The 1st-3rd filter fine streaks F1-F3 are arrayed regularly and the lengthwise directions of these streaks are tilted toward the n-th, (n+1)-th and (n+2)-th horizontal scanning lines, etc. Thus a stripe filter is obtained. at the same time, the tilting angles, the widths, etc., of the streaks F1-F3 are selected so that just two scanning lines are set against the pitch set in the direction where those streaks are orthogonal to the scanning line. As a result, a phase difference is set at 180 deg. between the scanning lines of the basic wave component signal. Thus, the basic wave component can be separated from a luminance signal so that the band of the basic wave component can be set within the luminance signal band that is conventionally impossible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color imaging device, and more particularly to a color imaging device in which light from an object is passed through an optical color separation striped filter (stripe filter) having a predetermined configuration to a photoconductive surface of an imaging tube ( The present invention relates to a color imaging device that forms an image on a photocathode (or a photocathode) and obtains a color television signal from a signal taken out from the imaging tube.

BACKGROUND OF THE INVENTION The present applicant previously proposed in Japanese Patent Publication No. 59-35550 a "color television signal generator" using a stripe filter having a predetermined configuration. This one is additive color method 3
A first filter strip that transmits only light of one of the primary colors, and light of one of the primary colors and the other two primary colors that passes through the first filter strip. A second filter strip that transmits only white light and a third filter strip that transmits white light are arranged in a certain order, and the longitudinal direction of each filter strip is perpendicular to the scanning direction. The light from the subject dances through the stripe filters, which are arranged in a regular pattern like this! & Of the signals applied to the photoconductive surface (or charging surface) of the tube and extracted from this image pickup tube, the fundamental wave component of a carrier wave having a spatial frequency value determined by the repetition period of the three types of filter strips in the stripe filter. When a predetermined two primary color signal is separated and generated from the second harmonic base of this carrier wave, only the phase component of the second harmonic base is used, and the amplitude component thereof is not used. It is.

According to the color television signal generator proposed by the present applicant, the influence of color shading caused by the different modulation degrees between the center and peripheral parts of the target surface of the image pickup tube can be determined only by the fundamental wave component. can be done, so the second
Compared to conventional devices that separate colors using the amplitude component of the bottom of the harmonic, the influence of color shading can be reduced, and it is also possible to separate and generate predetermined two primary color signals by means of average value detection. Therefore, it is possible to reduce color errors compared to equipment that uses envelope detection, and is also almost unaffected by noise in the second harmonic band, making it possible to generate color television signals of good image quality. It has excellent features such as:

Problems to be Solved by the Invention However, according to the apparatus proposed by the present applicant, in the frequency spectrum shown in FIG. Since predetermined two primary color signals are generated separately using the harmonic band B, the band of the luminance signal is determined by the optical system with predetermined spectral characteristics so that the band does not overlap with the fundamental wave component A, as shown by Y in the figure. The band was limited by a low pass filter.

Therefore, in order to obtain higher resolution, it is necessary to make the stripe filter's filter strips (one period longer and the pitch) more rigid, and correspondingly widen the preamplifier band. However, the noise distribution of the preamplifier is
As shown in the figure, noise tends to increase non-linearly as the frequency increases, so even if you try to increase the resolution by adjusting the pitch of the stripe filter, the S/N of the second harmonic base will increase. There is a problem in that it is difficult to improve the resolution beyond a predetermined value because the resolution deteriorates.

Furthermore, in the proposed device, when separating the fundamental wave component signal and the luminance signal, a separation error occurs for the image pickup tube output signal that has no vertical correlation.

In particular, when the subject has a gradient of brightness or darkness that gradually becomes brighter or darker, a level difference always occurs between the image pickup tube outputs for each horizontal scanning line, as shown in FIG. 7, for example.

Therefore, a separation error corresponding to the level difference between the image pickup tube outputs of two adjacent horizontal scanning lines occurs over a large area of the screen, and there is also the problem that, for example, some color appears in an area that should be white. Ta.

Therefore, the present invention makes the longitudinal direction of each filter strip of the stripe filter inclined with respect to the scanning line direction, and
It is an object of the present invention to provide a color imaging device that solves the above problems by adjusting the level of the image pickup tube output signal of each horizontal scanning line.

Means for Solving the Problems The color imaging device of the present invention arranges predetermined first to third filter strips in a fixed order, and the longitudinal direction of each filter strip is inclined with respect to the scanning direction. The light from the subject is passed through the stripe filter, which is configured by arranging the stripes as shown in FIG. The luminance signal q and
The fundamental wave component signals within the luminance signal band are separately output.

Operation: The first filter strip transmits only the first primary color light of any one of the three additive primary colors;
The filter strips of the first primary color light and the second primary color light of any one of the other two primary colors other than the first primary color light.
The third filter strip transmits only white light mixed with the primary color light.

These first to third filter strips constitute a stripe filter whose longitudinal direction is inclined with respect to the scanning line direction, and the image pickup tube output signal is divided into two adjacent scanning lines due to this inclination. A phase difference is given between the fundamental wave component signals in the output signal of. This phase difference is determined by how the number of scanning lines is set with respect to the pitch of the stripe filter viewed in the direction perpendicular to the scanning lines.

Therefore, by utilizing the vertical correlation of the image pickup tube output signals of each horizontal scanning line, the fundamental wave component and the luminance signal can be separated. Therefore, it becomes possible to set the band of the fundamental wave component within the luminance signal band, which was previously impossible.

The number of scanning lines for the pitch of the first to third filter strips may be any number.

Here, first, with respect to the image pickup tube output signal of one scanning line, a composite output signal of each image pickup tube output signal of at least two scanning lines adjacent to one scanning line is made to have substantially the same level. next,
By utilizing the vertical correlation of these signals, the fundamental wave component signal and the luminance signal are separately output.

Actual tIM811I FIG. 1 shows a stripe filter structure of a first embodiment of the present invention. In FIG. 1, Fl is the first filter strip that transmits only the first primary color light of any one of the three additive primary colors, and F2 is the first filter strip that transmits Fl. F3 is a second filter strip that transmits only a mixed color light of a primary color light and a second primary color light of any one of two other primary colors other than the primary color; The third filter strip is transparent. Here, - by way of example, the first filter strip F1 is a filter strip that transmits only green light, and the second filter strip F1 is a filter strip that transmits only green light.
2 will be explained below assuming that it is a filter strip that transmits only cyan light.

As shown in FIG. 1, the first to third filter strips F1 to F3 are regularly arranged in a certain order, and their longitudinal direction is nth and nthousandth.

A stripe filter is arranged so as to be inclined with respect to the direction of each horizontal scanning line such as the (n+2)th line.

Also, the inclination angle is set so that exactly two scanning lines are located with respect to the pitch (indicated by P in FIG. 1) in the direction perpendicular to the scanning lines of the first to third filter strips F+ to F3. , the width of each filter strip, etc. is greenhouse. As a result, the phase difference between the scanning lines of the fundamental wave component signal becomes 180°. Further, the phase difference between the scanning lines of the second harmonic bottom signal is always twice that of the fundamental wave component signal, so it is 360''.

Next, the configuration of an embodiment of the present invention will be explained with reference to the block diagram shown in FIG. 2. In FIG. Thereafter, the light passes through the stripe filter 2 and is imaged on the photoconductive surface of the image pickup tube 3, where it is photoelectrically converted. The stripe filter 2 is built into the image pickup tube 3 and has a structure as shown in FIG. The electrical signal taken out from the signal electrode of the image pickup tube 3 is supplied to a preamplifier 4, where it is amplified to an appropriate level and then supplied to a separation circuit 5, which forms the essential part of the present invention.

Now, assuming that the output signal of the preamplifier 4 is 81, 81 becomes as shown in the following equation.

2 ・Sr = (ic+ −+B 12 I HR) ± A
si (ωt+Φ) + −A−5in(2ωt−+l +−” where, i, iB, iR are current signals due to green light, blue light, and red light, and f+ is the stripe filter 2
It is a spatial frequency determined by the repetition period of the filter strip F+"-F3 in the horizontal scanning line direction. Also, the phases of the odd-order harmonic component signal and the fundamental component signal are 1 as can be seen from equation (1). Phase inversion during horizontal scanning period (180
with a phase difference of °).

As can be seen from equation (1), this output signal S+ includes a DC signal and a luminance signal which are mixed signals of the three primary colors of the additive coloring method, a carrier wave of the above spatial frequency f1, a carrier wave of an integral multiple of this spatial frequency f1, etc. is composed of a modulated color signal which is amplitude-modulated and phase-modulated by a mixed signal of two primary color lights (red and blue light) other than the green light transmitted through the first filter strip F+.

Fig. 3 (A> shows the frequency spectrum of this output signal SI. In Fig. 3 (A), ■1 and
+1st fundamental wave component of each scanning period, ■η and M I
m indicates the sideband of the fundamental wave component signal in each of the n-th and n+1-th scanning periods. Also, ■η.

■ηt1 is the carrier wave f of each scanning period of nth and n+ith
The second harmonic bottom signal of z (=2f+), IV
n, rVη (1 indicates its sideband.

As can be seen from FIG. 3(A), in two adjacent scanning lines, the fundamental wave component signals are in opposite phases to each other, and as will be described later, vertical correlation can be used, so the luminance signal is indicated by V. The characteristics of the optical low-pass filter 1 are set so as to have a wide band up to the frequency f2. That is, in the past, the band of the luminance signal occupied a lower range than the fundamental wave component signal, as shown by Y in FIG. 5, but in this embodiment, the fundamental component signal is within the band V of the luminance signal. The bandwidth is twice as wide as before.

Next, the separation circuit 5, which is the main part of the present invention, will be explained with reference to FIG. In FIG. 4, the above output signal S1 is supplied to a 1Hil delay circuit 22 via an input terminal 21, where it is extended for one horizontal scanning period (1)-1>ff.

The output signal of the 1Hiff delay circuit 22 is supplied to an adder 23 and a reducer 24, respectively, and is also supplied to a 1-day delay circuit 25 where it is further delayed by 11-1. In this way,
The output signal of the one-day delay circuit 25, which has been delayed by a total of 42H, is attenuated to 1/2 in level by an amplifier 26 and supplied to an adder 23 and a subtracter 24, respectively. On the other hand, the output signal S1 is attenuated to 1/2 in level by an amplifier 27, and then supplied to an adder 23 and a subtracter 24, respectively.

Here, the current horizontal scanning line is (n+2) (where n is a natural number) lines, 1)'' and the horizontal scanning line from two days ago is (n+
1> line and n line. In this case, the subtractor 24
subtracts the sum of the (n+2) line and n line image tube output signals whose levels have been attenuated to 1/2, respectively, from the (n+1) line Ill picture tube output signal. Here, the seventh
When there is a brightness gradient as shown in the figure, the sum of the image pickup tube output signals of the <n+2) line and the n line whose level has been attenuated to 1/2 and the image pickup tube output signal of the (n+1) line are approximately at the same level. . Therefore, the subtracter 24 outputs the difference between the signals that are at the same level to the output terminal 28.

Similarly to the above, the adder 23 calculates the sum of the image pickup tube output signals of the (n+1) line, which are at the same level, and the image pickup tube output signals of the (r++2) line and the n line, whose levels are attenuated to 1/2, respectively. are added and output to the output terminal 29.

As described above, in the present invention, when imaging an object having a brightness gradient as shown in FIG. The feature is that addition and subtraction are performed after signal level adjustment.

Here, as mentioned above, while the luminance signal and the second harmonic component signal are in phase in each horizontal scanning period,
Since the phase of the fundamental wave component signal is inverted every horizontal scanning period, the subtracter 24 removes the luminance signal, the second harmonic component, and its sideband, as shown by the solid line in FIG. 3(B). Signal S2 consisting only of the fundamental wave component signal and its sideband ■
is taken out.

On the other hand, as shown by the solid line in FIG. 3(C), the adder 23 outputs the luminance signal V, the second harmonic component signal (2), and its sideband, from which the fundamental wave component signal and its sidebands have been removed. A signal S3 consisting of a band (■) and a band (3) is extracted.

Referring again to FIG. 2, the output signal S2 of the separation circuit 5 is converted into a P-wave from the fundamental wave component signal S4 by the bandpass filter 6 having the required passband width indicated by the broken line ▪ in FIG. 3(B).

On the other hand, the signal S3 is passed through the bandpass filter 7 with the required passband width shown by the broken line ■ in FIG.
Here, the luminance signal indicated by V in Fig. 3(C) is 111F.
The signal is waved and output to the output terminal 9. Although not shown, the signal 983 is a DC signal of the first term on the right side of equation (1) converted into a P wave by a low-pass filter, and is supplied to a color separation matrix circuit (not shown). Here, S4 and Ss are expressed by the following formula.

S4 = A 5in (ωt+ψ) ■The above signal S5 is made into a signal with a constant amplitude by the amplitude limiter 10, and then is supplied to the hooking circuit 11, where it is multiplied by the signal S4, and is further converted into a fundamental wave component signal. The signal is supplied to an adder 13 and a subtracter 14 through a bandpass filter 12 that only allows the signal to pass.

The output signal of the adder 13 is outputted to the output terminal 16 through the detection circuit 15. Further, the output signal of the subtracter 14 is outputted to the output terminal 18 through the detection circuit 17. Separation circuit 5
The circuit after the output side is disclosed in the color television signal generator proposed by the applicant, and the adder 1
3 and the subtracter 14, both of which are single carrier waves and whose amplitudes vary depending on the color, are extracted from the detection circuit 1.
5 and 17, detection is performed not only by envelope detection and square law detection, but also by average value detection. Detection circuit 15.1
A blue signal and a red signal are obtained from the output detection signal of 7 by the matrix circuit. Further, a green signal is obtained by matrixing the normal three-color sum signal and these primary color signals.

Note that the second harmonic component signal is transmitted through the 1H''il extension circuit 22.
．． It is also possible to separate and extract using a bandpass filter without using 25.

Note that the configuration and operation of the separation circuit 5, which is the main part of the present invention, is not limited to that shown in FIG. 4, and other configurations and operations may be used. Further, the number of scanning lines used for signal separation is not limited to this embodiment, and may be three or more.

Further, the present invention is not limited to the above embodiments, and the number of scanning lines with respect to the pitch of the stripe filter in the direction orthogonal to the scanning lines is not limited to an even number (two), but may be an odd number.

Furthermore, in the embodiment of the stripe filter shown in FIG. 1, the phase difference between the fundamental wave component signals between two adjacent scanning lines does not have to be exactly 180 degrees, but is within a practically allowable range. Within this range, it may be 180°±θ.

In addition, the slope of each of the first to third filter strips F1 to F3 with respect to the horizontal scanning line in the longitudinal direction is determined by the slope between the 62 adjacent scanning lines in order to separate and extract the fundamental wave component signal and the luminance signal. Since it is provided to obtain a phase difference between wave component signals, the direction of the slope may be opposite to that of the embodiment shown in FIG. Furthermore, the circuit configuration on the output side of the separation circuit 5 can be applied to each embodiment of the device proposed by the present applicant.

According to the present invention, the longitudinal direction of each filter strip of the stripe filter is inclined with respect to the scanning line direction, and the fundamental wave component signal is arranged within the luminance signal band. Since the fundamental wave component signal and the luminance signal are separated using the vertical correlation, the luminance signal band can be made twice as wide as the conventional one when using the same color multiplex frequency as before. As a result, the resolution can be greatly improved compared to the conventional method, and the fundamental wave component signal and luminance signal are separated after adjusting the level of the image pickup tube output for each horizontal scanning line. Therefore, for example, by adjusting the level even for subjects with no vertical correlation, it is possible to separate the double sign using the vertical correlation, and furthermore, the fundamental wave component signal frequency is the same as that of the conventional device. This is good, since there is no need to widen the band of the preamplifier and the second harmonic bottom signal can be obtained with good S/N.
It has features such as being able to improve the S/N ratio of color signals.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the stripe filter structure of the first embodiment of the present invention, Fig. 2 is a block system diagram of one embodiment of the invention, and Fig. 3 is a frequency diagram for explaining the operation of the block system shown in Fig. 2. 4 is a block system diagram showing an embodiment of the main part of the present invention, FIG. 5 is a diagram showing the frequency spectrum of a signal used in the device previously proposed by the applicant, and FIG. 6 is a spectrum diagram. FIG. 7 is a diagram showing the noise distribution of the preamplifier, and FIG. 7 is a diagram showing the imaging output of an example of an uncorrelated subject. DESCRIPTION OF SYMBOLS 1... Optical low-pass filter, 2... Strive filter, 3... Image pickup tube, 5... Separation circuit, 21...
・Image tube output signal input terminal, 22.25...1 day delay circuit, 26.27...Amplifier, 23...Additional if! f
, 24... Subtractor, 28.29... Output terminal, Fl
...first filter strip, F2...second filter strip, F3...third filter strip. Patent applicant Japan Victor Co., Ltd. disease 4 diagram. Figure 5

Claims (1)

[Claims] a first filter strip that transmits only the first primary color light of any one of the three additive primary colors; Any one
a second filter strip that transmits only the mixed color light of the second primary color light of the two primary colors and the first primary color light, and a third filter strip that transmits the white light, in a certain order, and , each filter strip is arranged so that its longitudinal direction is inclined with respect to the scanning line direction, and the number of scanning lines is selected with respect to the pitch of the first to third filter strips in the direction perpendicular to the scanning line. Applying light from the subject to the photoconductive surface (or photocathode) of the image pickup tube through the configured stripe filter,
A luminance signal taken out from the image pickup tube, a fundamental wave component signal obtained by amplitude-modulating and phase-modulating a carrier wave having a spatial frequency value determined by the repetition period in the scanning line direction of the first to third filter strips, and the fundamental wave component signal. Among the harmonic component signals of the wave component signal, the fundamental wave component signal is set within the band of the luminance signal, and at least The combined output signal of each image pickup tube output signal of the two scanning lines is made to be at approximately the same level, and the fundamental wave component signal and the luminance signal are respectively output separately by utilizing the vertical correlation of these signals. color imaging device.