JPS63185185A - Color image pickup device - Google Patents

Abstract

PURPOSE:To raise resolution by inclining the stretcher direction of each filter stripe of a stripe filter for a scanning line and simultaneously suppressing the amplitude error of a dominant wave component signal based on the border signal of a luminance signal. CONSTITUTION:The prescribed first to third filter stripes F1-F3 are arranged in the fixed order and to incline the stretcher direction of each filter stripe F1-F3 for the direction of the scanning line. The light from a substance to be scanned is given to the light conductive surface of an image pickup tube through the stripe filter composed by selecting the number of the scanning line for the pitch of the first to the third filter stripes F1-F3 in the perpendicular direction to the scanning line. The luminance signal and the dominant wave component signal in the zone of the luminance signal are respectively isolated and outputted by utilizing the perpendicular correlativity of an output signal from the image pickup tube of leastwise two horizontal scanning lines. The amplitude error of the isolated dominant wave component signal is corrected based on the border signal of the luminance signal. Thus the resolution can be widely improved.

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 extracted from this image.

BACKGROUND OF THE INVENTION In Japanese Patent Publication No. 59-35550, applicant G proposed a ``color television signal generator'' using a stripe filter having a predetermined configuration. This method consists of a first filter strip that transmits only light of one of the three primary colors of the additive color method, and a first filter strip that transmits light of the primary color and light of the other two primary colors. A second filter strip that transmits only mixed color light with any one of the primary colors of light and a third filter strip that transmits white light are arranged in a certain order, and each filter strip is Light from the subject is applied to the photoconductive surface (or photocathode) on the m image through stripe filters that are regularly arranged so that the longitudinal direction is perpendicular to the scanning direction, and among the signals extracted from this image pickup tube, , when separating and generating predetermined two primary color signals from a fundamental wave component of a carrier wave having an interval frequency value determined by the repetition period of the three types of filter strips in the stripe filter and a second harmonic component of this carrier wave. As for the second harmonic component, only the phase 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 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 length of the stripe filter strips of the stripe filter finer (the length and pitch of one cycle of the filter strips) and to correspondingly widen the band of the preamplifier. However, the noise distribution of the preamplifier is
As shown in the figure, noise tends to increase non-linearly as the number of harmonics 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 increase. There is a problem in that it is difficult to improve the resolution beyond a predetermined value because the resolution deteriorates.

Therefore, the present invention solves the above problem by tilting the longitudinal direction of each filter strip of the stripe filter with respect to the scanning line and suppressing the amplitude error of the fundamental wave component signal based on the contour signal of the luminance signal. An object of the present invention is to provide a color imaging device that solves the above problems.

Means for Solving the Problems The color imaging device of the present invention arranges predetermined first to fifth filter strips in a fixed order, and the longitudinal direction of each filter strip is aligned with respect to the scanning direction. The light from the object is passed through the stripe filter, which is arranged so as to be inclined and configured by selecting the number of scanning lines relative to the pitch of the first to third filter strips in the direction orthogonal to the scanning line, to the photoconductive conductor of the image pickup tube. A luminance signal and a fundamental component signal within a luminance signal band are separately outputted by utilizing the vertical correlation of the image pickup tube output signals of at least two horizontal scanning lines. The amplitude error of the separated fundamental wave component signal is corrected based on the contour signal of the luminance signal.

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 due to this inclination, the fi image ratio output signal is A phase difference is given between the fundamental wave component signals in the output signal of the line. 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 II image ratio 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.

Incidentally, the fundamental wave component signal in the portion without vertical correlation includes an amplitude error. In order to suppress this amplitude error, the amplitude error of the separated fundamental wave component signal is corrected based on the contour signal of the luminance signal.

Example FIG. 1 shows a block diagram of an embodiment of the present invention.

In this embodiment, a contour signal is generated by suppressing the vicinity of the fundamental wave component frequency of the fundamental wave component signal separated in the separation circuit 5 described later, and based on this contour signal, the vertical correlation of the fundamental wave component signal is eliminated. It is configured to correct the amplitude error of the part.

Before explaining FIG. 1, the structure of the stripe filter according to the present invention will be explained together with FIG. 2.

In Figure 2, F+ 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 the mixed color light of the first primary color light and the second primary color light of any one of the other two primary colors other than the primary color of this primary color light; A third filter strip that transmits white light. As an example, the first filter strip F1 is assumed to be a filter strip that transmits only green light, and the filter strip F2 of the vehicle 2 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.

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 F1 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°. Furthermore, 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. 1. In FIG. After that, 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.

Now, assuming that the output signal of the preamplifier 4 is 81, $1 becomes as shown in the following equation.

±A'5tn(ωt+ψ) where, iG, iB, and 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 f, and a carrier wave of an integral multiple of this spatial frequency ft. etc., are amplitude-modulated and phase-modulated by a mixed signal of two primary color lights (red light and blue light) other than green light transmitted through the first filter strip F+. .

FIG. 3(A) shows the frequency spectrum of this output signal S1. In the same figure (A), ■1 and ■η (1 is the nth and nth
+1st fundamental wave component signal of each scanning period, ■η and ■
1+1 indicates the sideband of the fundamental wave component signal in each of the n-th and n+1-th scanning periods. In addition, ■η and ■ηt1 are the carrier waves fz (=2f+
) is the second harmonic component signal, and ■η and ■ηt1 indicate its sidebands.

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 that it has a wide band up to the frequency f2, as shown in FIG. However, in this embodiment, the fundamental wave component signal is set within the band V of the luminance signal,
The band is twice as wide as the conventional one.

The separation circuit 5 has a configuration as shown in FIG. For convenience of explanation, a case will be described in which a subject is photographed in which the central part of the screen is white and the peripheral part of the screen is black, as shown in FIG. Further, in FIG. 5, the camera tube output signal a (i.e., the output signal MS+) as shown in FIG. 6(A), which corresponds to the video signal in the vertical scanning direction indicated by the dashed line It is assumed that the signal is input to the input terminal 21 inside. Furthermore, it is assumed that the overall level of the signal a is 2, and the level of the fundamental wave component thereof is expressed as m.

In FIG. 4, a signal a is converted by a multiplier 22 into a signal @b whose level is reduced to 1/2 as shown in FIG. be done.

Further, the signal a is delayed by one horizontal scanning period (one day) in the 11'' delay circuit 25, and is supplied as a signal C as shown in FIG. 6(C) to the adder 23 and the subtracter 24, respectively. . The signal C is further delayed by 1H in the 1-day delay circuit 26, and then its level is set to 172 in the multiplier 27, and the signal d as shown in FIG. are supplied to the containers 24, respectively.

Here, as shown in FIGS. 6(B) to (D), the signal d
The levels of both are Il/2 (also, the fundamental wave components are both m
/2), and the level of signal @C is 2 (also, the fundamental wave component is m). Furthermore, 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 shift of 180° in each horizontal scanning period (i.e. , phase invert). Therefore, the fundamental wave components of signals S and d are in phase, but the phase of signal C is opposite to that of signals S and d.

The subtracter 24 subtracts the signals S and d from the signal @C to generate a signal e (signal S2) as shown in FIG. 6(E).

On the other hand, the fundamental wave suppression circuit 28 includes, for example, a coil.

Cutoff frequency f1 consisting of capacitor C and resistor R
It consists of a well-known low-pass filter (LPF). The fundamental wave suppression circuit 28 suppresses the frequency of the fundamental wave component of the incoming signal e and generates a signal f as shown in FIG. 6(F). This signal has the same waveform as the contour signal of the known luminance signal, and is output at the output terminal 2 as the contour signal Co.
9.

Furthermore, the signal S2 taken out from the subtracter 24 is as shown by the solid line in FIG. It consists of only the wave band ■ and is output to the output terminal 30.

On the other hand, addition! 23, as shown by the solid line in FIG. 3(C), consists of the luminance signal V, the second harmonic component signal (■) and its sideband (■) from which the fundamental wave component signal and its sideband have been removed. The signal @S3 is taken out and output to the output terminal 31.

Returning to FIG. 1 again, the signal S2 is shown in FIG. 3 (B
), the fundamental wave component signal S4 is converted into a P wave by a bandpass filter 6 having a required passband width indicated by a broken line ■.

Next, the gain controller 7, which is a main part of the present invention, controls the gain of the fundamental wave component signal S4 based on the contour signal Go from the separation circuit 5 to vary its amplitude.

By the way, when the fundamental wave component signal S4 is separated using the image pickup tube output signal S1 of two horizontal scanning lines, its waveform and the waveform of the contour signal C8 become as shown in FIG. 7(A).

In other words, the portion R+ surrounded by the broken line in FIG.
Alternatively, since there is no vertical correlation in parts like R2, where there is a sharp change from black to white or from white to black, an amplitude error corresponding to the level difference between white and black can occur as shown in Figure 7 (A). This occurs in the fundamental wave component signal S4 shown in FIG. Similarly, when the fundamental wave component signal S4 is separated using the image pickup tube output signal @s1 of 3 horizontal scanning lines, its waveform and the waveform of the contour signal Co become as shown in FIG. 7(B). .

In this case, the gain controller 7 increases the gain of the fundamental wave component signal S4 during the high level period of the contour signal Go, while the gain of the contour signal c increases.

By reducing the gain of the fundamental wave component signal S4 during the low level period, the amplitude error of the fundamental wave component signal can be corrected.

In this way, the gain controller 7 outputs the contour signal G
A signal 84' obtained by correcting the amplitude error of the portion of the fundamental wave component signal S4 having no vertical correlation based on the signal S4 is output.

On the other hand, the output signal S3 of the separation circuit 5 is passed through a bandpass filter 8 having a required passband width as shown by the broken line Vl in FIG. 3(C).
The P-wave of the harmonic component signal S5 is supplied to the low-pass filter 9, where the luminance signal indicated by V in FIG. 3C is separated into the P-wave and output to the output terminal 10. In addition,
Although not shown, the signal S3 is filtered by a low-pass filter (1
) is filtered and supplied to a color separation matrix circuit (not shown). Here, 84
, Ss are expressed by the following equation.

84 = A 5in (ωt + ψ) ■The above signal S5 is made into a signal with a constant amplitude by the amplitude limiter 11, and then supplied to the multiplication circuit 12, where it is multiplied by the signal S4' and further converted into a fundamental wave component signal. Adder 14 and subtracter 1 through bandpass filter 13 that only passes
5, respectively.

The output signal of the adder 14 is outputted to the output terminal 17 through the detection circuit 16. Further, the output signal of the subtracter 15 is outputted to an output terminal 19 through a 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
4 and the subtracter 15, both of which are single carrier waves and whose amplitudes vary depending on the color, are extracted from the detection circuit 1.
6 and 18, detection is performed not only by envelope detection and square law detection, but also by average value detection. Detection circuit 16.1
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 DC 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.

It should be noted that the present invention is not limited to the above-described embodiment, and the configuration of the separation port 5 is not limited to that shown in FIG. 4, of course. Further, the amplitude error of the portion of the fundamental wave component having no vertical correlation may be corrected by means other than the gain controller 7. Further, the method of generating the contour signal is not limited to the method of generating the contour signal by suppressing the fundamental wave component signal using the fundamental wave suppression circuit 28, but may be generated using other methods.

Furthermore, 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 by providing a delay means or a phase shifting means according to the number of scanning lines, it is possible to capture images of at least two scanning lines. The fundamental wave component signal and the luminance signal can be separated based on the tube output signal.

In addition, 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 need to be exactly 180 degrees, which is acceptable in practice. 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.1. In addition, the fundamental wave component signal is arranged within the luminance signal band, and the fundamental wave component signal and the luminance signal are separated using vertical correlation. In this case, the luminance signal band can be made twice as wide as that of the conventional device, and thereby the resolution can be greatly improved compared to the conventional device, and the fundamental wave component signal frequency can be the same as that of the conventional device. There is no need to widen the band of the preamplifier, and the second harmonic component signal is S/
Since the S/N of the chrominance signal can be improved, the amplitude error of the fundamental wave component signal is suppressed based on the contour signal of the luminance signal, so the vertical correlation in the fundamental wave component signal can be improved. This has the advantage that it is possible to obtain a good color signal by correcting amplitude errors that occur in areas where there is no color.

[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 a stripe filter structure of an embodiment of the present invention,
3 and 7 are respectively explanatory diagrams of the operation of the block system shown in FIG. 1, FIG. 4 is a block system diagram showing an embodiment of the main part of the present invention, and FIG. FIG. 8 is a diagram showing the frequency spectrum of a signal used in the device previously proposed by the applicant, and FIG. 9 is a diagram showing the noise distribution of the preamplifier. DESCRIPTION OF SYMBOLS 1... Optical low-pass filter, 2... Strive filter, 3... Image pickup tube, 5... Separation circuit, 7...
Gain controller, 21... Decoy image output signal input terminal, 22.27... Multiplier, 23... Adder, 24
...Subtractor, 25.26...1 day delay circuit, 28.
... Fundamental wave suppression circuit, 29 ... Contour signal output terminal, 3
0... Fundamental wave component signal output terminal, 31... Luminance signal and second harmonic compensated signal output terminal, Fl... First filter strip, F2... Second filter strip, F3...
Third filter strip. ×2 6th (3) Time-

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 an interval frequency value determined by the repetition period of the first to third filter strips in the scanning line direction; 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. What is claimed is: 1. A color imaging device that separates and outputs each signal using vertical correlation, the device being characterized in that the amplitude error of the fundamental wave component signal is corrected based on the contour signal of the luminance signal.