JPS63175591A - Color image pickup device - Google Patents

Abstract

PURPOSE:To improve resolution remarkably by tilting the lengthwise direction of each filter stripe of a stripe filter with respect to the scanning line direction and arranging a fundamental wave component signal in a luminance signal band to separate the fundamental wave component signal and the luminance signal respectively. CONSTITUTION:Prescribed 1st-3rd filter stripes F1-F3 are arranged in a prescribed order in a way that the lengthwise direction of the filter stripes F1-F3 is tilted in the scanning direction and light from an object is given to the photoconductive face of a photoelectric face of an image pickup tube 3 through a stripe filter 2, and the vertical correlation of the output signal of the image pickup tube of a least two horizontal scanning lines is utilized and a circuit comprising filters 7-10, 14, 21 is used to output the luminance signal and the fundamental wave component signal in the luminance signal band separately respectively. Thus, the band of the fundamental wave component is set in the luminance signal band, which has been impossible for a conventional device and then the broad band twice the conventional device is attained. Then the resolution is improved remarkably.

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 in the image pickup tube onto the snow surface (
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 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 with good image quality. It has excellent features such as:

Problems to be Solved by the Invention However, according to the device proposed by the applicant, in the horizontal frequency spectrum shown in FIG.
Since predetermined two primary color signals are separately generated using the fundamental wave component Δ of 1 and the second harmonic component B of the carrier wave f2 (=2ft), the band of the luminance signal is as shown by Y in the figure. The band was limited by an optical low-pass filter with predetermined spectral characteristics so that the band did not overlap with the fundamental wave component A.

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, when the fundamental wave component signal is separated from the image pickup tube output signal using two horizontal scanning lines, the fundamental wave component band in the vertical direction is wide, and the fundamental wave component signal and the luminance signal cross in the vertical direction. There was also the problem that talk occurred and separation was insufficient.

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 limiting and separating at least the fundamental wave component in its vertical band.

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 arranged as shown in FIG. The luminance signal and the fundamental wave component signal within the luminance signal band are respectively applied to the photocathode) by utilizing the vertical correlation of the image pickup tube output signals of at least two horizontal scanning lines and using a circuit consisting of a filter. Separate 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 two primary colors other than the primary color of the first primary color light and 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 different from that of two adjacent scanning lines due to this inclination. A phase difference is given between the fundamental wave component signals in the output signal. This phase difference is determined by how the number of scanning lines is set with respect to the big 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 62 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 big of the first to third filter strips may be any number.

After the fundamental wave component signal in the vertical direction of the image pickup tube output signal is band-limited by a filter, the fundamental wave component signal in the horizontal direction is filtered. In this way, the fundamental wave component signal is separated and extracted from the image pickup tube output signal.

Embodiment FIG. 1 shows a block system diagram of an embodiment of the present invention. As will be described later, the present invention is characterized in that a cyclic filter is provided to limit the fundamental wave component band in the vertical direction. Here, before explaining Figure 1,
First, the structure of a stripe filter, which is another feature of the present invention, will be explained with reference to FIG.

In FIG. 2, 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 of the primary color light; is the third filter strip that transmits. Here, as an example, the first filter strip F1 is a filter strip that transmits only green light, and the second filter strip F2 is described below as a filter strip that transmits only cyan light. do.

As shown in FIG. 2, 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.

This constitutes a stripe filter arranged so as to be inclined with respect to the direction of each horizontal scanning line such as the n+2th one.

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 component signal is always twice that of the fundamental wave component signal, so it is 3606.

Next, FIG. 1 will be explained. In FIG. 1, light from a subject (not shown) has its spatial frequency band-limited by an optical low-pass filter 1, passes through a stripe filter 2, and is imaged on the photoconductive surface of an image pickup tube 3. is photoelectrically converted. The stripe filter 2 is built into the image pickup tube 3 and has a structure as shown in FIG. Image tube 3
The electrical signal extracted from the signal electrode is supplied to the preamplifier 4, where it is amplified to an appropriate level.

Now, if the output horn signal of the preamplifier 4 is 81, Sl
is as shown in the following equation.

± A 5in(ωt+ψ) Here, :Q,! B and iR are current signals based on green light, blue light, and red' light, and fl is a spatial frequency determined by the repetition period of the filter strips F+ to F3 of the striped filter 2 in the horizontal scanning line direction. Furthermore, the phases of the odd harmonic component signal and the fundamental wave component signal are inverted every horizontal scanning period (18
with a phase difference of 0').

As can be seen from equation (1), this output horn signal S1 includes a DC signal and a luminance signal, which are mixed signals of the three primary colors of the additive coloring method.
The carrier wave with the spatial frequency f1 and the carrier wave with an integer multiple of the spatial frequency f1 are generated 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 F1. and a modulated color signal in the form of amplitude modulation and phase modulation, respectively.

FIG. 3(A) shows the horizontal frequency spectrum of this output signal S1. In the same figure (A), η and I y+n
are the fundamental wave component signals of the n-th and n+1-th scanning periods, and ■η and II m+ indicate the sidebands of the fundamental wave component signals of the n-th and n+i-th scanning periods. Also, ■η, ■η
+1 is the carrier wave f2 of each scanning period of n-th and n+1-th
(=2ft) second harmonic component signal, ■η,
rVtni indicates its sideband.

As can be seen from FIG. 3(A), the fundamental wave component signals are in opposite phases to each other in two adjacent scanning lines, 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 the low range of the fundamental wave component signal AJ, as shown by Y in FIG. 6, but in this embodiment,
The fundamental wave component signal is set within the band V of the luminance signal, which is twice as wide as the conventional one.

However, when the fundamental wave component signal is set within the luminance signal band as described above, there is a problem that crosstalk occurs in the vertical direction as described above. That is, the spatial frequency distribution seen in the vertical direction in the above case becomes as shown in FIG. Here, Ys represents a luminance signal band, As represents a fundamental wave component, and Bs represents a second harmonic component.

If the fundamental wave components are separated using two horizontal scanning lines, the fundamental wave component band in the vertical direction becomes wider than that in the horizontal direction, as shown by the broken line a1 in FIG. Therefore, in the vertical direction, there is a lot of crosstalk between the fundamental wave component signal and the luminance signal, resulting in insufficient separation.

The present invention was created in view of the above points, and is characterized by providing a recursive filter having a bandpass characteristic number as shown by the dashed line a2 in FIG.

In FIG. 1, the output signal $1 of the preamplifier 4 is delayed by one horizontal scanning period (1H) by a one-day delay circuit 5 and then supplied to an adder 6. On the other hand, the output signal S1 is directly supplied to the cyclic filter 7.

The recursive filter 7 has a known configuration as shown in FIG. 5, and has a configuration and a coefficient β (however,
0≦β≦1), etc. are set.

Here, the output signal S1 that enters the input terminal 31 is multiplied by a coefficient (1-β) in the multiplier 32, and then
, where they are added to the output signal of the multiplier 34, respectively. The output signal of the adder 33 is directly supplied to the subtracter 35, and is also supplied to the subtracter 35 after being delayed by 1H by a one-day delay circuit 36. The output signal of the subtracter 35 is output to an output terminal 37, and after being multiplied by a coefficient β in the multiplier 34, it is supplied to the adder 33.

As mentioned 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. As shown by the solid line in FIG. 3(B), the luminance signal, the second harmonic component and its sideband are removed, and a signal $2 consisting only of the fundamental wave component band and its sideband 2 is extracted.

On the other hand, as shown in FIG. 3(C) by the solid line, the adder 6 shown in FIG. A signal S3 consisting of the harmonic component signal (2) and its sideband (2) is extracted.

Next, the signal S2 is subjected to a P-wave of the fundamental wave component signal S4 by a bandpass filter 8 having a required passband width in one horizontal direction, as shown by a broken line 3 in FIG. 3(B). On the other hand, the signal S3 is shown in FIG.
The second harmonic component signal S5 is passed through the bandpass filter 9 with the required passband width in the horizontal direction indicated by the dashed line ■ in FIG.
), the luminance signal indicated by V is outputted to the output terminal 11. Although not shown, the signal S3
The DC signal of the first term on the right side of equation (1) is filtered by a low-pass filter and supplied to a color separation matrix circuit (not shown). Here, Sa and Ss are expressed by the following formula.

Sa = A 5in (ωt+ψ) ■S
5 =-i'-5in(2ωt-$) (3
) The above signal S5 is made into a constant amplitude signal by an amplitude limiter 12, and then supplied to a multiplication circuit 13, where it is multiplied by the above signal S4, and then passed through a bandpass filter 4 that passes only the fundamental wave component signal. Adder 15 and subtracter 1
6, respectively.

The output signal of the adder 15 is outputted to the output terminal 18 through the detection circuit 17. Further, the output signal of the stem reducer 16 is outputted to the output terminal 20 through the detection circuit 19. The circuits after the output side of the decorator 6 and the recursive filter 7 are disclosed in the color television signal generation device proposed by the present applicant, and from the adder 15 and the subtracter 16, both Since a signal whose amplitude changes depending on the color is extracted using the carrier wave, the detection circuits 17 and 19 perform detection not only by envelope detection and square law detection but also by average value detection. A blue signal and a red signal are obtained from the output detection signals of the detection circuits 17 and 19 through the RIX circuit 71. Further, a green signal is obtained by matrixing the six streams of three-color mixed signals and these primary color signals.

Incidentally, in this embodiment, the cyclic filter 7 is used only for separating the fundamental wave component, but as shown by the broken line in FIG. 1, the cyclic filter 2 is also used for separating the second harmonic component.
1 may be used. In this case, the circuit configuration is changed so that the output signal S3 of the adder 6 is output only to the low-pass filter 10 and the IPF (not shown), and the output signal of the cyclic filter 21 is supplied to the bandpass filter 9. be done. The configuration of this cyclic filter 21 is similar to that in FIG. 5, in which an adder is used instead of the subtracter 35, and the cyclic filter 21 converts the signal S3 from the incoming output signal S1 into a P wave. What is necessary is to output it to the bandpass filter 9.

Note that the configuration of the cyclic filter 6 is not limited to that shown in FIG.

Further, it goes without saying that the filter for generating P waves in the fundamental wave component band in the vertical direction is not limited to the configuration of a so-called cyclic filter.

Furthermore, the present invention is not limited to the above-described embodiments, and the number of scanning lines for the bits 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 image pickup tube output signals of at least two scanning lines.

On the other hand, in the embodiment of the stripe filter shown in FIG. , it may be 180°±θ.

Furthermore, in order to separate and extract the fundamental wave component signal and the luminance signal, the slope of each of the first to third filter strips [1 to 3 with respect to the horizontal scanning line in the longitudinal direction Since it is provided to obtain a phase difference between fundamental wave component signals between lines, the direction of the slope may be opposite to that of the embodiment shown in FIG.

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 bottom signal is S
/N can be obtained, so the S/N of the color signal can be made at least on the same level as before.Furthermore, since at least the fundamental wave component is separated by limiting its vertical and horizontal bands, the vertical The crosstalk of the luminance signal to the fundamental wave component signal can also be reduced, and therefore, it has the advantage of being able to perform good color imaging.

[Brief explanation of the drawing]

Fig. 1 is a block system diagram of an embodiment of the present invention, Fig. 2 is an explanatory diagram of the structure of the stripe filter in the present invention, and Fig. 3 is a horizontal frequency diagram for explaining the operation of the block system shown in Fig. 1. 4 is a vertical frequency spectrum diagram of the block system shown in FIG. 1, FIG. 5 is a block system diagram showing an embodiment of the main part of the present invention, and FIG. FIG. 7 is a diagram showing the frequency spectrum of the signal used in the proposed device, and FIG. 7 is a diagram showing the noise distribution of the preamplifier. 1... Optical low-pass filter, 2... Live filter, 3... Image pickup tube, 5, 36... 11'' delay circuit, 6.33... Adder, 7, 21...・Cyclic form-
Filter, 31... Input terminal, 32.34... Multiplier, 35... Subtractor, 37... Output terminal, Fl...
- First filter strip, F2... second filter strip, F3... third filter strip. Figure 4 Figure 5 Yu Figure 7 Illne(wa(

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 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 uses vertical correlation to separate and output the respective fundamental wave component signals, wherein the fundamental wave component signals are separated and extracted from the image pickup tube output signal using a filter that band-limits the fundamental wave component signals in the vertical direction. A color imaging device characterized by: