JPS63175592A - Color image pickup device - Google Patents

Abstract

PURPOSE:To prevent fogging of a luminance signal in the vertical direction caused by separation using a vertical correlativity by using a low-frequency component having a frequency lower than the fundamental wave component frequency in an output signal of an image pickup tube as the low-frequency component of the luminance signal without separation using the vertical correlativity. CONSTITUTION:A fundamental wave suppression circuit 29 consists of a low-pass filter having a low-pass characteristic L having a cut-off frequency f0 shown in the figure, for example, and the frequency f0 is set lower then the fundamental wave component frequency f1. On the other hand, a fundamental wave suppression circuit 31 and a subtractor 32 constitute a high-pass filter (HPF) 33. An adder 30 adds a low-frequency component from the circuit 29 and a high-frequency component from the HPF 33 respectively to generate a signal S3' having a frequency spectrum and outputs it as a luminance signal. Thus, the signal S3' is separated by utilizing the vertical correlativity only with respect to the high-frequency component having the frequency f0 or over and the low frequency below the frequency f0 is taken out while not using a vertical correlativity, then the fog in the vertical direction is decreased.

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 mixed color 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. Light from the subject is passed through striped filters arranged regularly on the photoconductive surface of the image pickup tube (
or a photocathode), and among the signals 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, and the secondary component of this carrier wave. When separately generating predetermined two primary color signals from harmonic components, only the phase component of the second harmonic component is used, and the amplitude component thereof is not used.

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 use amplitude components of harmonic components to separate colors, the influence of color shading can be reduced, and two predetermined primary color signals can be separated and generated using average value detection. It can reduce color errors compared to envelope detection devices, is almost unaffected by noise in the second harmonic band, and can generate color television signals with good image quality. It has excellent features.

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 separated and generated using harmonic component B, the band of the luminance signal is an optical low pass 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 filter.

Therefore, in order to obtain higher resolution, it is necessary to make the stripe filter's filter strips (the length of one cycle of the filter strips) finer and to correspondingly widen the band of the preamplifier. , the noise distribution of the preamplifier is the seventh
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 making the pitch of the stripe filter finer, the S/N of the second harmonic component will decrease. There is a problem in that it is difficult to improve the resolution beyond a predetermined value because the resolution deteriorates.

On the other hand, as will be described later, if the luminance signal is separated by, for example, adding the image pickup tube output signals of at least two horizontal scanning lines, the luminance signal will become blurred in the vertical direction, and the resolution in the vertical direction will deteriorate. There were also points.

Therefore, the present invention makes the longitudinal direction of each filter strip of the striped filter inclined with respect to the scanning line direction, and
Provided is a color imaging device that solves the above problems by using the low frequency components below the fundamental frequency component frequency in the image pickup tube output signal as they are as the low frequency components of the luminance signal without separating them using vertical correlation. The purpose is to

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. a stripe filter configured by arranging the stripe filter as shown in FIG. Equipped with: Light from the subject is applied to the photoconductive surface (or photocathode) of the image pickup tube through the stripe filter, and the vertical correlation of the image pickup tube output signals of at least two horizontal scanning lines is used to generate a luminance signal and a luminance signal band. The fundamental component signals within 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 at least two horizontal scanning lines, 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.

Next, the first filter filters out the low frequency components of the image pickup tube output signal below the frequency fo (where 1<f+, f+ is the fundamental wave component signal frequency).

On the other hand, the second filter filters out high-frequency components having a frequency fo or higher of the separated luminance signal. Thereafter, the adding means adds the low-frequency component and the high-frequency component, respectively, and outputs a signal obtained as a luminance signal.

Embodiment FIG. 1 shows a block system diagram of an embodiment of the present invention. In order to eliminate the vertical blurring of the luminance signal that occurs when the luminance signal is separated using vertical correlation, the present invention uses the image pickup tube output signal as it is for the low frequency component of the luminance signal, On the other hand, for the high frequency component of the luminance signal, the present invention is characterized in that a signal separated from the image pickup tube output signal is used by utilizing vertical correlation.

Before explaining FIG. 1, the structure of a stripe filter, which is another feature of the present invention, will be explained with reference to FIG. 2. In FIG. 2, El 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. A second filter strip that transmits only the mixed color light of the primary color light and the second primary color light of any one of the other two primary colors other than the primary color of the primary color light;
is a third filter strip that transmits white light. As an example, the first filter strip F+ is assumed to be a filter strip that transmits only green light, and the second filter strip F2 is assumed to be 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 n+1th.

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. 2) 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. are selected. As a result, the phase difference between the scanning lines of the fundamental wave component signal becomes 180°. Also, 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 3606.

Next, the overall configuration of the present invention will be explained with reference to the block system diagram shown in FIG. 3. In FIG. , 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 extracted from the signal electrode of the image pickup tube 3 is supplied to the preamplifier 4,
After being amplified to an appropriate level, the signal is supplied to the separation circuit 5, which forms the main part of the present invention.

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

S+-(ic, +1' I HR)+[]+ ± △ sin (ωt+ψ) + -A-sin (2ω to 1ψ) + ,,,
(1) Here, i, iB, iR are current signals caused by green light, blue light, and red light, and fl is the stripe filter 2
is the spatial frequency determined by the repetition period of the filter strips F1 to F3 in the horizontal scanning line direction. In addition, the phases of the odd harmonic component signal and the fundamental wave component signal are inverted every horizontal scanning period (180
” phase difference).

As can be seen from equation (1), this output signal S1 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 modulated color signals that are amplitude-modulated and phase-modulated by a mixed signal of two primary color lights (red light and blue light) other than the green light transmitted through the first filter strip F+.

FIG. 4(A) shows the frequency spectrum of this output signal S+. In the same figure (A), ■η and ■η÷1 are n-th and n
+i-th fundamental wave component signal of each scanning period, ■η and I
I il+I indicates the sideband of the fundamental wave component signal in each of the n-th and n+1-th scanning periods. Also, ■η, ■η÷1 is n
Carrier wave fz (-2
f + ) second harmonic component signal, ■η, IVil
ll indicates its sideband.

As can be seen from FIG. 4(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 A, as shown by Y in FIG. 6, but in this embodiment, the fundamental wave component signal is within the band V of the luminance signal. is set to
The band is twice as wide as the conventional one.

Next, the configuration and operation of the separation circuit 5, which is the main part of the present invention, will be explained with reference to FIG. In the figure, the output signal S1 enters the input terminal 21 and is delayed by one horizontal scanning period (1H) in the one-day delay circuit 22. Also, the output signal S
The level of z is reduced to 1/2 by the multiplier 23 and then supplied to the adder 24 and the subtracter 25, respectively. On the other hand, the 1H delay circuit 26 further increases the output signal of the 1H delay circuit 22 by 1H.
The signal obtained after being delayed by H is supplied to a multiplier 27, where its level is reduced to 1/2, and then outputted to an adder 24 and a subtracter 25, respectively.

The subtracter 25 converts the level of the image pickup tube output signal S+ from the one-day delay circuit 22 1H ago to 1/2 of the current and 2H ago output signals from the multipliers 23 and 27. Deduct each. Here, as described above, the luminance signal and the second harmonic component signal are in phase in each horizontal scanning period, whereas the fundamental wave component signal has a phase inversion every horizontal scanning period, so the subtracter 25 As shown by the solid line in FIG. 4(B), the luminance signal, the second harmonic component, and its sideband are removed, and a signal S2 consisting only of the fundamental wave component and its sideband is extracted. The signal is then output to the output terminal 28.

On the other hand, the adder 24 receives the image pickup tube output signal S1 from 1H before from the 1H delay circuit 22, and the image pickup tube output signal SI whose level has been converted to 1/2 of the current and two previous signals from multipliers 23 and 27, respectively. to add.

As a result, the fundamental wave component signal and its sidebands are removed from the adder 24, as shown by the solid line in FIG. 4(C).
Luminance signal V, second harmonic component signal ■ and its sideband ■
A signal S3 consisting of is extracted.

Next, the fundamental wave suppression circuit 29 operates at a cutoff frequency f shown in FIG. 5, for example. It is composed of a low-pass filter (LPF) that controls the low-pass characteristics of the filter.

Here, the cutoff frequency fo is the fundamental wave component frequency f
It is set lower than 1. The fundamental wave suppression circuit 29 uses the cutoff frequency f of the image pickup tube output signal S1 1H before the one-day delay circuit 22.

Adder 3 adds the low-frequency components obtained by suppressing the fundamental wave components, etc.
Output to 0. As shown in FIG. 5, this low-frequency component does not include the fundamental wave component (2), etc., and consists only of the low-frequency component of the luminance signal V.

On the other hand, the fundamental wave suppression circuit 31 and the subtracter 32 constitute a high-pass filter (eye PF) 33. Here, the fundamental wave suppression circuit 31 has the same low-pass characteristic as the fundamental wave suppression circuit 29 -I! Using an LPF with lL, 1''P F
32 has a high-pass characteristic H with a cutoff frequency fo as shown in FIG.

The subtracter 32 subtracts, from the output signal S3 of the adder 24, the low frequency component that has been suppressed from the output signal S3 by the fundamental wave suppression circuit 31, and generates and outputs a high frequency component. As shown in FIGS. 4(C) and 5, this high frequency component includes a component having a cutoff frequency of 10 or more of the luminance signal V and a second harmonic bottom signal (2).

The adder 30 adds the low frequency components from the fundamental wave suppression circuit 29 and the high frequency components from the IPF 33 to generate a signal 83' having a frequency spectrum as shown in FIG. 4(C). , is output to the output terminal 34. here,
Similarly to the signal S3, the signal Sa' is the luminance signal V and the second
It consists of the harmonic bottom signal ■, but the frequency of the luminance signal V -
[For the low-frequency part below 0, the low-frequency part of the image pickup tube output signal S1 from one day ago is used as is, while the luminance signal V
The frequency f. Regarding the above high frequency part and second harmonic bottom signal ■, the signal $3 separated using vertical correlation is
The difference is that the high frequency part of .

In this way, the signal S3 has a frequency of 3 over its entire frequency range.
Since the signal is separated using the vertical correlation of the image pickup tube output signal of the horizontal scanning line, the luminance signal V in this signal S3 is blurred in the vertical direction as described above. In contrast, the signal 83' has a frequency f. Since only the above high frequency components are separated using vertical correlation, and the low frequency components below frequency fo are extracted without using vertical correlation, signal S3' is signal $3. The blur in the vertical direction is reduced compared to the above.

Referring again to FIG. 3, the fundamental wave component signal S4 of the output signal S2 of the separation circuit 5 is filtered by the bandpass filter 6 having the required passband width indicated by the broken line ■ in FIG. 4(B). On the other hand, the signal S3' is supplied to the low-pass filter 8 while the second harmonic bottom signal S5 is filtered by the bandpass filter 7 having the required passband width indicated by the broken line ■ in FIG. 4(C). Here, the luminance signal indicated by V in FIG. 4(C) is separated and filtered and outputted to the output terminal 9. Although not shown, the DC signal of the first term on the right side of equation (1) is filtered by a low-pass filter and the signal S3' is supplied to a color separation matrix circuit (not shown).

Here, S4. S5 is expressed by the following formula.

34 = A 5in (ωt+ψ)
■S 5 = -1 no-5in (2ω t
-φ) c3) The above signal S5 is made into a signal with a constant amplitude by the amplitude limiter 10, and then supplied to the multiplication circuit 11, where it is multiplied by the signal S4, and further, only the fundamental wave component signal is passed. Adder 13 through bandpass filter 2
and the subtracter 14, respectively.

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 an output terminal 18 through a 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 subtractor -14, both of which are single carrier waves and whose amplitude changes depending on the color are taken out. Therefore, the detection circuits 15 and 17 perform not only envelope detection and square law detection, but also
Detection is also performed by average value detection. Detection circuit 15
．． A blue signal and a red signal are obtained from the output detection signal of 17 by the matrix circuit. Furthermore, by matrixing the DC three-color mixed signal and these primary color signals,
You will get a green signal.

Note that the second harmonic component signal can also be separated and extracted using a bandpass filter.

It should be noted that the present invention is not limited to the above-described embodiment, and the configuration of the separation circuit 5 is of course not limited to that shown in FIG. 1. Moreover, as the fundamental wave suppression circuits 29 and 31 in the separation circuit 5, a circuit that suppresses the fundamental wave other than the LPF, such as a bandpass filter, may be used.

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 perpendicular to the scanning lines may be an odd number, and the delay means and phase shift according to the number of scanning lines may be used. By providing the means, it is possible to separate the fundamental wave component signal and the luminance signal based on the bottle picture tube output signals of at least two scanning lines.

Furthermore, in the embodiment of the stripe filter shown in FIG. 2, the phase difference between the fundamental wave component signals between two adjacent scanning lines does not have to be exactly 180 degrees, and is within a practically acceptable 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 between two 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 the fundamental 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.

Effects of the Invention As described above, 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 before when using the same color multiplex frequency as before. As a result, the resolution can be greatly improved compared to the conventional device, and since the fundamental wave component signal frequency can be the same as the conventional device, there is no need to widen the band of the preamplifier, and the second The harmonic component signal is S
/N can be obtained, so the S/N of the color signal can be at least on the same level as the conventional one.Furthermore, the low-frequency components below the fundamental wave component frequency in the image pickup tube output signal can be obtained by utilizing vertical correlation. Since it is used as a low-frequency component of the luminance signal as it is without separation, it is possible to prevent vertical blurring of the luminance signal, that is, deterioration of vertical resolution, which would result from separation using vertical correlation. Therefore, it has the advantage of being able to perform good color imaging.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a stripe filter structure of an embodiment of the present invention,
3 is a block system diagram of the entire invention, FIG. 4 is a frequency spectrum diagram for explaining the operation of the block system shown in FIGS. 1 and 3, and FIG. 5 is a frequency spectrum diagram for explaining the operation of the block system shown in FIG. 1. 6 is a diagram showing the frequency spectrum of a signal used in the device previously proposed by the present applicant, and FIG. 7 is a diagram showing the noise distribution of the preamplifier. 1... Optical low-pass filter, 2... Stripe filter, 3... Image pickup tube, 2... Separation circuit, 21...
Camera tube output signal input terminal, 22.26... 1H delay circuit, 23.27... Multiplier, 24.30... Adder, 25°32... Subtractor, 28... Fundamental wave Component signal output terminal, 29.31... Fundamental wave suppression circuit, 33...
- High-pass filter (HPF), 34... Luminance signal and second harmonic component signal output terminal, Fl... First filter strip, F2... Second filter strip, F3... - Third filter strip.

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 extracted from the image pickup tube, a fundamental wave component signal obtained by amplitude-modulating and phase-modulating a carrier wave with a spatial frequency f_1 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 the fundamental wave component signal and the luminance signal are set in the image pickup tube output signal of at least two horizontal scanning lines. A color imaging device that separates and outputs each using vertical correlation, the first filter filtering a low frequency component of frequency f_0 (however, f_0<f_1) of the image pickup tube output signal; a second filter for filtering high-frequency components having a frequency f_0 or more of the luminance signal; and an adding means for outputting a signal obtained by adding the low-frequency component and the high-frequency component as a luminance signal. A color imaging device featuring: