JPS63169889A - Color image pickup device - Google Patents

Abstract

PURPOSE:To prevent occurrence of a chrominance false signal by tilting the lengthwise direction of each filter fine streak of a stribe filter toward a scanning line to set the basic wave component signal within a luminance signal band and therefore attenuating an area near the basic wave space frequency component of an object having no vertical correlation. CONSTITUTION: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. as a result, a stripe filter is obtained. The tilting angle of each fine streak is set at 45 deg., for example, and at the same time the tilting angles and the widths, etc., of these streaks are selected to that just two scanning lines are set against the pitch set in the direction where the streaks F1-F3 are orthogonal to the scanning line. Thus a phase difference is set at 180 deg. between the scanning lines of the basic wave component signal. While a phase difference is set at 360 deg. between the scanning lines of a 2nd higher harmonic component signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color imaging device, and particularly to a color imaging device that captures light from a subject through an optical low-pass filter and an optical color separation striped filter (stripe filter) each having a predetermined configuration. 1l
The present invention relates to a color m-image device that forms an image on the photoconductive surface (or photocathode) of a Hil tube and obtains a color television signal from the signal taken out from the image pickup 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. The light from the subject is applied to the photoconductive surface (or photocathode) of the 1111 tube through a striped filter arranged regularly in the image pickup tube, and among the signals extracted from this image pickup tube, the three types of filter stripes in the striped filter are When separating and generating predetermined two primary color signals from a fundamental wave component of a carrier wave having a spatial frequency value determined by the repetition period of , and a second harmonic component of this carrier wave, the second harmonic component is only a phase component. The configuration is such that the amplitude component 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 is possible to reduce color errors compared to equipment that uses envelope detection, and it 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 apparatus proposed by the present applicant, in the frequency spectrum shown in FIG. Since predetermined two primary color signals are separated and generated using the harmonic component B, 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.

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
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 bits of the stripe filter finer, the S/N of the second harmonic component will decrease. Since it will deteriorate, the solution F that is higher than the predetermined value! There was a problem in that it was difficult to improve A-level.

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
It is an object of the present invention to provide a color imaging device that solves the above problems by providing an optical low-pass filter that band-limits at least the fundamental spatial frequency component in a direction perpendicular to the longitudinal direction of each filter strip.

Means for Solving the Problems The color imaging device of the present invention is characterized in that an optical low-pass filter and a stripe filter are arranged and configured in a predetermined manner. Here, the stripe filter includes predetermined first to third filter strips in a certain order, and
The filter strips are arranged so that the longitudinal direction of each filter strip is inclined with respect to the scanning direction, and the scanning line is selected to correspond to the pitch of the first to third filter strips in the direction perpendicular to the scanning line. The light from the subject passes through the optical low-pass filter and the stripe filter, and the photoconductive surface (or photocathode) of the image pickup tube converts the light from the subject into a luminance signal and a luminance signal using the vertical correlation of the image pickup tube output signals of at least two horizontal scanning lines. The fundamental wave component signals within the signal band are separately output.

Function: The optical low-pass filter band-limits at least the fundamental spatial frequency component in a direction orthogonal to the longitudinal direction of each filter strip among the spatial frequency components of the incident light from the subject, and supplies it to the stripe filter. The first filter strip transmits only the first primary color light of any one of the three additive primary colors, and the second filter strip transmits only the first primary color light other than the first primary color light. The third filter strip transmits white light, and the third filter strip transmits white 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 acid in the output signal and the f signal. This phase difference is determined by how the number of scanning lines is set for the bits 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.

Embodiment FIG. 1 shows the structure and arrangement of an optical low-pass filter and a stripe filter according to 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 - as an example, the first
In the following description, the 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 Fl-F3 are regularly arranged in a certain order, and their longitudinal direction is nth and n+1.

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. As an example, it is assumed here that the angle of inclination of each filter strip is set to 45[deg.].

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 FI-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°. Furthermore, the phase difference between the scanning lines of the second harmonic component signal is always twice that of the fundamental component signal, so it is 360°.

Next, the configuration of an embodiment of the present invention will be explained with reference to the block system diagram in FIG. 4. In FIG. After the spatial frequency is band-limited by an optical low-pass filter 1 to be described later, the light passes through a 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 camera 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.

Now, if the output signal of the preamplifier 4 is 8+, then Sl
is as shown in the following equation.

± A 5in (ωt 1ψ ) + −A−S
in (2ωt-ψ)±-(1) where, i(,, iB, iR are the current signals due to green light, blue light, and red light, and fl is the filter strip F1 of the striped filter 2. It is a spatial frequency determined by the repetition period of ~F3 in the horizontal scanning line direction.In addition, the phases of the odd-numbered harmonic component signal and the fundamental wave component signal are phase-inverted during one horizontal scanning period, as can be seen from equation (1). Do (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 modulated color signals that are amplitude-modulated and phase-modulated, respectively, by a mixed signal of two primary color lights (red and blue light) other than the green light transmitted through the first filter strip F1.

FIG. 5(A) shows the frequency spectrum of this output signal S1. In the same figure (A), Engineering 1 and Engineering 1 are the n-th and n-th
In the fundamental wave component of each +1st scanning period, ■η and ■Tsukuda indicate sidebands of the fundamental wave component signal of each of the nth and n+1th scanning periods. Also, Iffn.

■ηt1 is the second harmonic component signal of the carrier wave fz (=2ft) in each scan period of the nth and n+'th, and I
Vt+, IVnn indicate its sideband.

As can be seen from FIG. 5(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, conventionally, the band of the luminance signal occupied a lower range than the fundamental wave component signal A, as shown by Y in FIG. 7, 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.

In FIG. 4, the above output signal S1 is output from the one-day delay circuit 6.
While the signal is delayed by one horizontal scanning period (one day) and supplied to the subtracter 7 and adder 8, respectively, it is directly supplied to the subtracter 7 and adder 8, respectively.

As mentioned above, the i degree signal and the second harmonic component signal must be in phase in each horizontal scanning period, whereas the fundamental wave component signal has a phase inversion every horizontal scanning period. is the luminance signal and the second signal as shown by the solid line in Fig. 5(B).
The harmonic components and their sidebands are removed, and a signal S2 consisting only of the fundamental signal component and its sidebands is extracted.

On the other hand, as shown by the solid line in FIG. 5(C), from the adder 8,
A signal S3 consisting of a luminance signal V, a second harmonic component signal (2) and its sideband (2) from which the fundamental wave component signal and its sideband have been removed is extracted.

The signal S2 is converted into a fundamental wave component signal S4 by a bandpass filter 9 having a required passband width as indicated by a broken line ■ in FIG. 5(B). On the other hand, the signal S3 is supplied with a second harmonic component signal S5 by the bandpass filter 10 having the required passband width indicated by the broken line ■ in FIG. The luminance signal indicated by V in FIG. 5(C) is separated and outputted to the output terminal 21. Although not shown, the signal S3 is passed through a low-pass filter as the DC signal of the first term on the right side of equation (1) and is supplied to a color separation matrix circuit (not shown). Here, S4. Ss is expressed by the following formula.

84 =A 5in(ωi+ψ) ■S
s=A sin<2ω is equal to ψ) (3) The above signal S5 is made into a signal with a constant amplitude by the amplitude limiter 12, and then supplied to the +l calculation circuit 13, where it is a) calculated with the signal S4. The signal is then passed through a bandpass filter 4 that allows only the fundamental wave component signal to pass, and then supplied to an adder I;

The output signal of the adder 15 is outputted to the output terminal 19 through the detection circuit 17. Further, the output signal of the subtracter 16 is outputted to the output terminal 20 through the detection circuit 18. 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
5 and the subtracter 16, both of which have a single carrier wave and whose amplitude changes depending on the color are taken out, so the detection circuit 1
7 and 18, detection is performed not only by envelope detection and square law detection, but also by average value detection. Detection circuit 17.1
A blue signal and a red signal are obtained from the output detection signal of 8 by the matrix circuit. Further, a green signal is obtained by matrixing the normal three-color mixed signal and these primary color signals.

Note that the second harmonic component signal can also be separated and extracted using a bandpass filter without using the 1HM extension circuit 6.

However, in this embodiment, the fundamental wave component signal and the luminance signal are separated using the vertical correlation of the image pickup tube output signals of at least two horizontal scanning lines. , the above-mentioned separation cannot be performed sufficiently, resulting in false color signals, resulting in a hue different from the original hue, or in places where no color is supposed to be colored.

Therefore, the present invention provides the above-mentioned color 1lfI! In the apparatus, the optical low-pass filter 1 has a predetermined configuration and arrangement.Next, each embodiment of the optical low-pass filter 1 will be described.

It is known that an image passed through an optical low-pass filter 1 as shown in FIG. 2 becomes a double image with a pitch S due to its birefringence. As shown in FIG. 3, the spatial frequency characteristic of this optical low-pass filter 1 is such that it is attenuated every integer multiple of the distance 2S, which is twice the pitch S. Moreover, the pitch S is a value determined according to the thickness t. Therefore, if the thickness t is set so that the relationship between the width W of a set of filter strips corresponding to the basic repetition period of the striped filter and the pitch S of the optical low-pass filter 1 is S-W/2, The spatial frequency component determined by the width W will be attenuated. In other words, if the pitch S is set in the above relationship, the fundamental wave spatial frequency in the direction orthogonal to the longitudinal direction of each filter strip among the spatial frequency components of the light from the subject entering the optical low-pass filter 1. components will be suppressed.

In the first embodiment of the present invention shown in FIG.
The optical low-pass filter 1 is arranged so that IfiW/2 and the direction of the pitch S is orthogonal to the longitudinal direction of each filter strip.

According to this embodiment, the longitudinal direction of each filter strip is inclined at an angle of 45° to the horizontal scanning direction, so that
．． The vertical and horizontal components of the optical low-pass filter 1 are both W/2("I. Also, the length of the negative set of filter strips in the horizontal scanning direction is F)W.

Therefore, the fundamental frequency component in the horizontal scanning direction determined by flW + 17) 1/2 times (7) circumference 111 (/″lr/2)
- The second harmonic frequency component 2 in the horizontal scanning direction, which has W, will be suppressed.

On the other hand, regarding the vertical scanning direction, the cutoff frequency of the spatial frequency in the vertical scanning direction of the optical low-pass filter 1 is f2 (-2f+), so the optical low-pass filter 1 The vicinity of the frequency component will be attenuated. As a result, the vicinity of the fundamental wave spatial frequency component in the vertical scanning direction is attenuated even for subjects without vertical correlation, thereby effectively preventing the generation of false signals.

In this way, in the first embodiment, the optical low-pass filter 1 that limits the spatial frequency components in the direction perpendicular to the longitudinal direction of each filter strip to 1.11 bands is provided, and the second harmonic space in the horizontal scanning direction is By suppressing frequency components and attenuating the vicinity of the fundamental wave spatial frequency component in the vertical scanning direction, it is possible to effectively prevent the generation of false signals.

Next, a second embodiment of the optical low-pass filter and stripe filter used in the present invention will be described with reference to FIG. In contrast to the first embodiment, which only attenuated the vicinity of the fundamental wave spatial frequency component in the vertical scanning direction, this embodiment suppresses the fundamental wave spatial frequency component in the vertical scanning direction almost completely, Therefore, the present invention is characterized in that generation of false signals is more effectively prevented.

The gist of the second embodiment is to provide, for example, two optical low-pass filters that band-limit the spatial frequency components in two directions, the longitudinal direction of each filter strip and the direction perpendicular thereto. Here, if an optical low-pass filter with a pitch of S+ is arranged in a direction perpendicular to the longitudinal direction of each filter strip, the result will be as shown in FIG. 6(A). Since this is the same configuration and arrangement as in FIG. 1, a description thereof will be omitted.

Next, when an optical low-pass filter with a pitch S2 is arranged in the same direction as the longitudinal direction of each filter strip, as shown in FIG. 6(B).
It will look like this. In this case, both the horizontal and vertical components of the optical low-pass filter are 82/(7).

Next, if two optical low-pass filters shown in FIGS. 6A and 6B are stacked, the configuration and arrangement shown in FIG. 6C will be obtained. In this case, S+ =82- 8
Then, the composite vector (synthetic bit) S3 of Sl and 82 in the vertical scanning direction is 33- (S/E) x
2=E7S.

Kokote, ftr note (DtllJ<S=W/2. P-4
Since it is r¥W, it becomes 83-P/2. Therefore, the sixth
According to the second embodiment as shown in Figure (C), the fundamental spatial frequency component in the vertical scanning direction is suppressed.

In the second embodiment described above, although the limit resolution is the same as that in the first embodiment, color false signals can be effectively suppressed for subjects without vertical correlation. Furthermore, since false signal components in the vertical direction with respect to the scanning line are effectively removed, the spread in the vertical direction is also increased, and the luminance signal separation error with respect to the horizontal line is also reduced.

Note that the angle of inclination of the longitudinal direction of each filter strip with respect to the horizontal scanning direction is not limited to 45°, and may be any other angle. Furthermore, the positional relationship between the optical low-pass filter 1 and the striped filter 2 is not necessarily limited to the longitudinal direction of each filter strip and the direction perpendicular thereto, and it goes without saying that it may include some errors. .

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 image pickup tube output signals of at least two scanning lines. Furthermore, in each of the embodiments of the stripe filter shown in FIGS. 1 and 6, the phase difference between the fundamental wave component signals between two adjacent scanning lines does not have to be exactly 180° or 90°. , 180°±θ within a practically acceptable range.

It may be 90°±θ.

Moreover, the first to third filter strips F! The slope with respect to the horizontal scanning line in the longitudinal direction of ~F3 is provided in order to obtain the phase difference of the fundamental wave component signal between two adjacent scanning lines in order to separate and extract the fundamental wave component signal and the luminance signal. Therefore, the direction of the inclination may be opposite to that of the embodiment shown in FIGS. 1 and 6. In this case, it goes without saying that the arrangement of the optical low-pass filter 1 is also reversed from that shown in FIGS. 1 and 6. 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, since the longitudinal direction of each filter strip of the stripe filter is inclined in the scanning line direction, the fundamental wave component signal can be arranged within the luminance signal band. It is possible to separate the fundamental wave component signal and the luminance signal by using vertical correlation, and when using the same color multiplex frequency as before, it is possible to make the iti signal band twice as wide as before. As a result, the resolution can be greatly improved compared to the conventional method, and since an optical low-pass filter is provided that limits the band of the fundamental spatial frequency component at least in the direction orthogonal to the longitudinal direction of each filter strip, In particular, the generation of color artifacts can be effectively prevented by attenuating the vicinity of the fundamental spatial frequency component of objects that have no vertical correlation.Furthermore, since the fundamental component signal frequency can be the same as that of conventional devices, It is not necessary to widen the band of the amplifier, and the second
Since the harmonic bottom signal can be obtained with a good S/N, it has the advantage that the S/N of the color signal can also be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the structure and arrangement of an optical low-pass filter and a stripe filter according to the first embodiment of the present invention, FIGS. 2 and 3 are diagrams showing the structure and characteristics of the optical low-pass filter, respectively, and FIG. A block system diagram of an embodiment of the present invention,
FIG. 5 is a frequency spectrum diagram for explaining the operation of the block system shown in FIG. 4, FIG. 6 is an explanatory diagram of the structure and arrangement of the optical low-pass filter and stripe filter of the second embodiment of the present invention, and FIG. 7 is the present application. FIG. 8 is a diagram showing the frequency spectrum of the signal used in the device previously proposed by the author, and FIG. 8 is a diagram showing the noise distribution of the preamplifier. DESCRIPTION OF SYMBOLS 1... Optical low-pass filter, 2... Stripe filter, 3... Picture tube, 5... Separation circuit, 21...
- Luminance signal output terminal, Fl...first filter strip,
F2...second filter strip, F3...third filter strip. Patent applicant: Japan Victor Co., Ltd. Seal Figure 2. Figure 6 Figure 7

Claims (2)

[Claims] (1) A first filter strip that transmits only the first primary color light of any one of the three primary colors of the additive color method, and two other primary colors other than the primary color of the first primary color light. a second filter strip that transmits only the mixed color light of the second primary color light of any one of the primary colors and the first primary color light; and a third filter strip that transmits the white light. arranging the filter strips in a certain order so that the longitudinal direction of each filter strip is inclined with respect to the scanning line direction, and scanning the pitch of the first to third filter strips in a direction perpendicular to the scanning line; The light from the subject is applied to the photoconductive surface (or photocathode) of the image pickup tube through a stripe filter configured with a selected number of lines, and the luminance signal extracted from the image pickup tube and the first
- A fundamental wave component signal in which a carrier wave with a spatial frequency value determined by the repetition period in the scanning line direction of the third filter strip is amplitude-modulated and phase-modulated, and a harmonic component signal of the fundamental wave component signal. Color imaging in which 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 separately output using the vertical correlation of the image pickup tube output signals of at least two horizontal scanning lines. An optical low-pass device that passes through the stripe filter after band-limiting at least a fundamental spatial frequency component in a direction orthogonal to the longitudinal direction of each filter strip among the spatial frequency components of incident light from a subject. A color imaging device characterized by comprising a filter. (2) The optical low-pass filter is configured to band-limit fundamental wave spatial frequency components in both the longitudinal direction of each filter strip and the direction perpendicular thereto among the spatial frequency components of the incident light from the subject. A color imaging device according to claim 1, characterized in that the color imaging device is configured as follows.