JPS5923151B2 - color imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention extracts a plurality of primary color signals from one image pickup tube,
The present invention relates to a color imaging device from which a standard color television signal is obtained.

The imaging methods that have already been announced for this type of device are:
It is roughly divided into frequency separation method and phase separation method.

However, the frequency separation method requires uniform high resolution over the entire scanning surface of the electron beam on the photoelectric conversion surface of the image pickup tube.
) signal] and the color of the high frequency component (for example, red army or blue old signal)
Since the image is taken out from the image pickup tube in the form of an addition, it is easily affected by the gamma of the image pickup tube, and there is a limit to the ability to stably obtain an image with little color unevenness and good white balance.

On the other hand, as is well known, the phase separation method has many advantages over the frequency separation method, which is susceptible to the influence of the image pickup tube. The difficulty lies in the need to obtain a stable reference phase signal for separation.

In one example of a phase separation method that has already been proposed, a reference phase signal (hereinafter referred to as an index signal) is generated by applying an alternating voltage whose phase is inverted for each scanning line between two transparent conductive electrodes. . For this reason, when the signal current flowing through the image pickup tube target section decreases, index signal saturation and unsaturation phenomena occur for each scanning line, resulting in R, G
, B (hereinafter referred to as color signal) and the index signal cannot be completely separated, resulting in a disadvantage that line crawl is likely to occur in the image. Furthermore, this method uses the vertical correlation of the image as a means of separating color signals and index signals, so when an object with little vertical correlation is imaged, it is difficult to separate the color signal and index signal. Complete separation becomes impossible. In addition, regardless of whether frequency separation or phase separation is used, in single-tube color cameras that have been proposed to date, the frequency bandwidth of the luminance signal is larger than that of the stripe filter used to sample the color signal. It has the disadvantage that it is difficult to obtain high-resolution images with few bead signals because it is limited by sidebands generated by repeated pitch and sampling.

The present invention provides a high-quality single-tube color imaging device that eliminates these drawbacks of the prior art and also reduces capacitive afterimages in photoconductive image pickup tubes such as vidicon.

The present invention will be explained below. First, in the present invention, as a means for separating a color signal and an index signal, a separation means based on frequency is used instead of using the vertical correlation of images.

In order to separate the index signal and color signal using such a frequency separation method, each signal must be obtained as completely independent information in terms of frequency and space, but in the present invention, the frequency band of the image pickup tube is Because the carrier frequencies of both are placed close together for the purpose of effective utilization, the index frequency is included within the sideband of the color signal, and the phase of the index signal is affected by the sideband of the color signal. It will be chaotic. In order to separate the index signal from the color signal without causing such disturbance, the vertical correlation of the image is used, but as mentioned above,
The color signal and the index signal are originally separated independently in terms of frequency, and therefore we are not trying to separate them based solely on vertical correlation, so even if the vertical correlation of the subject is poor, Separation is fully possible. That is, only when sidebands of the color signal occur near the index frequency, it is sufficient that the objects have a correlation, and the possibility that the phase of the index signal will be disturbed is extremely reduced. In order to synchronously detect the color signal using the index signal separated in this way and reproduce the color information as an image, it is necessary to frequency convert the index signal to the same frequency as the carrier frequency of the color signal. There is. In this frequency conversion, unless the color carrier wave is an integer multiple of the index signal, it becomes necessary to convert the frequency of the index signal to a fraction of an integer. 3/
When the frequency is set to 2, a method is used in which the index signal is once counted down to 1/3, then counted up to twice the frequency, and converted to the same frequency as the color carrier wave.

Frequency conversion using a flip-flop or the like is extremely effective as a means of reliably counting down without losing the phase information of the index signal, but it goes without saying that the index signal must be a continuous wave within one horizontal scanning period. Therefore, a continuous countdown without disturbance of the relative phase with the color stripe filter is required over the entire horizontal scanning period.

However, with the general means used for continuous wave countdown, once the index signal is temporarily lost during the horizontal scanning period due to some reason (for example, a defect in the photoelectric conversion surface), the color stripe filter is disabled. It is no longer possible to count down the index signal while maintaining the same phase relationship as initially (before the index signal was lost) with respect to the relative position of each color. The present invention eliminates these drawbacks. G. A second index signal is set to obtain phase information for each color of the B color stripe filter, and when counting down the index signal (hereinafter referred to as the first index signal), the phase information is determined from the second index signal. By providing this information, it is possible to count down the first index signal while maintaining the correct phase relationship for each color of the color stripe filter.

This second index signal is set to a frequency ratio of a function of 1/integer with respect to the first index signal, and is multiplexed with the first index signal. In other words, the first index signal, which is set at a certain frequency ratio with respect to the color signal carrier wave, is frequency-modulated with a relatively low modulation index, and the frequency-modulated wave is FM-demodulated.
Obtain the index signal. Next, the index signal generation mechanism in the present invention will be explained.

In the present invention, an index signal for color separation is obtained based on the magnitude of impedance (so-called beam impedance) when an electron beam reaches a scanning surface of a photoelectric conversion surface of an image pickup tube and a current flows therethrough.

That is, in general, in an image pickup tube such as a vidicon, when an electron beam emitted from the cathode reaches the photoelectric conversion surface, the capacitance of the pixel on the photoelectric conversion surface is charged through the impedance of the path, and the charging current increases. It is well known that the electron beam is extracted as an output signal from the image pickup tube, but in the present invention, the electron beam is made to reach the photoelectric conversion surface even during the horizontal retrace period, and at the same time, the electron beam is transmitted to each of the separated transparent conductive electrodes. By creating a difference in the impedance of the corresponding paths, a potential pattern serving as an index signal is generated on the photoelectric conversion surface, and the index signal is read simultaneously with the video signal during the scanning period. Hereinafter, the index signal generation mechanism of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is an explanatory diagram schematically representing the equivalent circuit of an image pickup tube such as a vidicon used in the present invention, and each pixel on the photoelectric conversion surface...1n11n+1, 1n+
2, 1n+3......... is expressed by a parallel circuit of a resistance r and a capacitance C as is well known, and it is also transparent by a method that will be described in detail later. The figure shows how the conductive electrode is divided into two parts, making it possible to supply different target voltages to adjacent pixels.

In other words, Bl and B2 in the figure can be considered to be different voltage supply terminals. Switch in the diagram・・・・・・・・・・・・
2n12n+1, 2n+2, 2n+3,...
. . . is an electron beam scanning represented by a row of switches, which can be thought of as being sequentially closed when the electron beam reaches each pixel. Also···········
・3n13n+1, 3n+2, 3n+3・・・・・・・
... represents the beam impedance when the electron beam reaches each pixel. A switch 108 and power supplies 122 and 123 are connected to the cathode 107 of the image pickup tube. (In this case, the power supplies 122 and 123 are the switch 10
8 and is connected in reverse polarity. )
In the figure, during the scanning period of the electron beam, the same target voltage is supplied to B1 and B2 through a load resistor (not shown), and the terminal 108a of the switch 108 is connected to the terminal 108.
Short-circuit the b terminal to allow normal image pickup tube operation.
However, during the horizontal blanking period, the terminal 108a of the switch is short-circuited to the terminal 108c, and the electron beam is allowed to reach the photoelectric conversion surface without being interrupted, thereby further photoelectrically converting the capacitance of the pixel. At that time, Bl, B2 in the diagram
If we make a difference in the target voltage supplied to each pixel, the impedance of the electron beam path depends on the target voltage, as shown in Figure 2, so the difference in the target voltage supplied to each pixel will leading to corresponding beam impedance differences. In this way, when an electron beam reaches the photoelectric conversion surface during the horizontal retrace period with a difference in beam impedance corresponding to each pixel, the amount of beam reaching each pixel will differ depending on the difference in beam impedance. Therefore, the amount of charge charged in the capacitance of each pixel is different, and after electron beam scanning during the horizontal retrace period, the surface potential of each pixel (in Figure 1...
・・・・・・4n14n+1, 4n+2, 4n+3・
・・・・・・・・・・・・) differences appear. This potential difference is read simultaneously with the video signal during the scanning period and used as an index signal. FIG. 3 is a diagram showing how the surface potential changes over time in order to explain in more detail the index generation process described above.

Now, due to the discharge of the charge of the capacitance of a pixel on a certain photoelectric conversion surface, the surface potential becomes E during a period of Tfl. −e1 and the time T during which the electron beam hits the pixel during horizontal scanning
During el, the capacitance of the pixel is charged and the surface potential is approximately E. descend to Immediately after descending, the same pixel is scanned again without interrupting the electron beam during the horizontal retrace period.
An index is written during Tbl during horizontal retrace scanning.
That is, by lowering the potential of one of Bl and B2 in FIG. 1 during the horizontal retrace period, a potential difference Vb is applied between the separated transparent conductive electrodes, and a When electron beam scanning is performed with the cathode potential lowered to Vkb by the power supply 122 in FIG. 1 under the condition that there is a difference in beam impedance as shown in FIG. The surface potential of the pixel corresponding to the electrode shown by the solid line in Figure 3 is charged to around the cathode potential Vkb by electron beam scanning during the horizontal blanking period, but the potential is lowered by Vb compared to the scanning period. The surface potential of the pixel corresponding to the electrode, that is, the electrode indicated by the broken line in FIG. 3, is lowered to approximately the same potential as the cathode voltage Vkb by lowering the electrode potential by Vb. Therefore, pixels are hardly charged during the horizontal retrace period. As a result, the third
A potential difference Vi serving as an index signal is generated between the two electrodes as shown in the figure, and this is generated during the scanning period Te2 after one frame.
It is read out from the target electrode at the same time as the video signal and becomes an index signal. As described above, in the present invention, a difference is created in the beam arrival rate to each pixel between the separated transparent conductive electrodes of the image pickup tube, in other words, as stated at the beginning, the beam path of the image pickup tube is changed. It has been explained that an index signal is obtained by providing a difference in impedance between pixels.

In addition, while this method provides a stable index signal, the time the electron beam hits the pixel is longer than in normal image pickup tube operation, which is a problem with the prior art. Another great feature is that it also reduces the capacitive afterimage of the image pickup tube. A detailed description will be given below based on FIG. 4. 101 is an image pickup tube such as a vidicon, 10
2 is its face plate, 103 is a stripe filter for color separation, 104 is a conductor glass, and 105 is the sixth
As shown in detail in FIG. 7, the transparent conductive electrode is divided into two in a comb-like shape, 106 is a photoelectric conversion surface, 107 is a cathode electrode that generates an electron beam, and 108 is a cathode connected to cathode electrode 107. This is a bias voltage source and corresponds to switch 108 and constant voltage sources 122 and 123 shown in FIG.

The operation of this switch 108 is shown by Vk in FIG. That is, the scan period potential (during the scan period, the terminal 108a in FIG.
and 108b are short-circuited and the cathode potential becomes 0 potential)
In contrast, a positive pulse voltage and a negative pulse voltage are alternately applied to the cathode electrode 107 every horizontal retrace period. This positive pulse voltage is given a voltage Vka that completely blocks the electron beam from the cathode, and blocks the electron beam every horizontal retrace period. Similarly, during the vertical retrace period, a positive voltage sufficient to block the electron beam is applied to the cathode electrode 107. During the horizontal blanking period when the terminal 108a of the switch 108 in FIG. 1 is short-circuited to 108c and a negative pulse voltage is applied to the cathode electrode 107,
photoelectric conversion surface 106 without blocking the electron beam from
is reached, and a potential change serving as an index signal is formed on the photoelectric conversion surface every other scanning line according to the principle already explained. The reason why index signals are written every other scanning line is that during the horizontal blanking period when index signals are not written, the electron beam from the cathode is cut off and the no-signal level is reached, as in the operation of a normal image pickup tube. obtained,
This is to facilitate DC reproduction of video signals. Returning to FIG. 4, 109 is a constant voltage power supply that supplies a DC voltage (target voltage VT) to the transparent conductive electrode of the image pickup tube 101, and 110
is a load resistance of the image pickup tube, 111 is a coupling capacitor that supplies the output signal of the image pickup tube to the preamplifier 112, and 113 is one of the two transparent conductive electrodes 105a and 105b, for example 1.
A transformer 114 is a drive circuit for supplying a negative pulse to the transformer 05a only during the horizontal retrace period. 115 is a first grid electrode of the image pickup tube 101, 116 is a beam acceleration electrode, 117 is a focusing electrode, 118 is a mesh electrode, 119
is a control circuit connected to the focusing electrode 117 and the first grid electrode 115 for controlling the amount of electron beam and its focusing state.

6 and 7 are model diagrams for explaining the target section of the image pickup tube 101 in more detail, and the stripe filter 103 and transparent conductive electrode 105 inside the image pickup tube 101 are shown in FIGS. 6 and 7. It is located. That is, 103,10
3R, 103G, and 103B are stripe filters for color separation that transmit only red, green, and blue colored light, respectively; 105a, 105b are transparent conductive electrodes divided into two in a comb-teeth shape; The transparent conductive electrodes 105a and 105b have different repetition frequencies and are arranged obliquely to the scanning direction of the electron beam. The purpose of this diagonal arrangement is to ensure separation of the color signal and index signal by varying the phase of the index signal extracted depending on the scanning line by the method whose principle has already been explained. The details will be described later. One of the electrodes 105a is supplied with a target voltage VT through a load resistor 110 and a transformer 113 as shown in FIG.
A target voltage is directly supplied to the terminal b through the load resistor 110.

Furthermore, the above-mentioned mixture of the color signal current and the index signal current is applied to both the transparent conductive electrode 105a and the transformer 113.
Via the secondary winding and via the electrode 105b directly a voltage drop is brought across the load resistor 110 and is transmitted to the preamplifier 112 through the respective coupling capacitor 111. In the imaging device configured as described above, during the horizontal retrace period every other horizontal scanning line, the drive circuit 114 and transformer 113 shown in FIG. If the terminal 108a of the switch 108 in FIG. 1 is short-circuited to 108c while applying a negative pulse voltage as shown in FIG. 5 Ta, the electron beam from the cathode is allowed to reach the photoelectric conversion surface without being blocked. , a potential change that becomes an index signal occurs on the photoelectric conversion surface. VS in FIG. 5 is an example of a vertical deflection current waveform that can be used in this embodiment, and this vertical deflection current and a normal sawtooth horizontal deflection current H
S is supplied to a vertical deflection coil 121 and a horizontal deflection coil 120 shown in FIG. This special vertical deflection current VS
However, when writing the index every horizontal retrace period, the vicinity of the photoelectric conversion surface scanned in the previous horizontal scanning period is
The charge pattern of the video signal on the photoelectric conversion surface can be determined by scanning the photoelectric conversion surface several times before horizontal scanning every horizontal retrace period, without scanning again during the horizontal retrace period. This makes it possible to generate index signals without disturbance. Furthermore, the control circuit 11 shown in FIG.
At step 9, one horizontal retrace line is written in which an index is written by applying a positive pulse voltage to the first grid 115 and focusing electrode 117 of the image pickup tube 101 as shown in FIG. By increasing the beam amount and weakening the focusing of the electron beam at regular intervals, the electron beam with its increased diameter will abundantly reach the photoelectric conversion surface.
As already explained, even if index signals are written every other horizontal scanning line, as shown in FIG.
A potential pattern serving as an index signal can be generated almost uniformly on the photoelectric conversion surface. Therefore, in each horizontal scanning period of the next frame, a mixed signal of a video signal and a substantially uniform index signal for each scanning line is obtained, and the index signal is written every other horizontal scanning line. Therefore, a no-signal period in which the electron beam is cut off is obtained during the horizontal retrace period every other horizontal scanning line, and direct current reproduction of the video signal can be easily performed. The above explanation describes the process of obtaining a mixed signal of a video signal and an index signal from the image pickup tube. As mentioned at the beginning, the image pickup apparatus according to the present invention performs optical modulation using the stripe filter 103 shown in FIG. The carrier frequency of the received color video signal and the repetition frequency of the index signal generated according to the divided transparent conductive electrodes 105a and 105b are as follows.
Therefore, it is necessary to convert the repetition frequency of the index signal to the same frequency as that of the color signal.

It has already been explained that the second index is used to perform this frequency conversion reliably.
The manner in which these index signals are obtained will be explained according to the figures. FIG. 7 shows the R.I. of the image pickup tube 101. G. The relative relationship between the B stripe filter 103 and the transparent conductive electrode 105 is shown in detail.

As an example, the repetition pitch PC of the stripe filter 103 is set so that the carrier frequency of the color signal is 4, and the repetition pitch PC of the stripe filter 103 is set to 3/2 times the index frequency, that is, 6MHZ, for the color carrier frequency of 4M. Thus, the first index signal is obtained according to the principle already explained, but the second index signal (with respect to the repetition frequency of the first index signal) is directly obtained from this separated transparent conductive electrode. , an index signal having a relationship of 1/integer) and the first index signal simultaneously, the repetition frequency of the second index signal (in Fig. 7, the repetition frequency is 1
The diagram shows a case where the frequency is set to /4, that is, 1M.

) with a repeating pitch of transparent conductive electrodes, Ps,
The repetition pitch of the first index signal is geometrically frequency modulated. Here, if the repetition frequency of the first index signal is given, PO1(PL+PH)
- 1/2, and PL and PH give the depth of modulation of the frequency repeated at the repetition pitch Ps of the second index signal, that is, the modulation index of the frequency modulation, as can be understood from Fig. 7. and the electrode pitches PL and P
The difference in H determines the maximum frequency deviation. By geometrically frequency modulating the transparent conductive electrodes separated in this way, the index signal M obtained from the photoelectric conversion surface is
To simply express F using the fundamental wave components of the carrier wave and modulation wave, MF=Isin(ω0t+MfSin(!)
St).

Here, 1: amplitude of the index signal ωo: 2πFO, FO is the fundamental wave ωs of the carrier signal that becomes the first index signal: 2πFs, Fs is the fundamental wave Mf of the modulation signal that becomes the second index signal: V is the modulation index and the electron beam speed scanning on the photoelectric conversion surface is
stripe filter 103 for one scanning electron beam;
If the inclination of the transparent conductive electrode 105 divided into two is θ as shown in FIG. 7, Δω is the maximum frequency deviation.

Similarly, if the video signal modulated by the stripe filter 103 is expressed as Ec, up to the fundamental wave component, the first term is the DC component that becomes the luminance signal, and the second term is the phase modulated by the stripe filter 103. represents the fundamental wave component of the color signal.

The video signal obtained from the image pickup tube 101 in this way,
The frequency vector of the mixed index signal is shown in FIG. FIG. 8 is an explanatory diagram of the waveforms of these signals. In FIG. 9, Fc is the carrier frequency of the color signal, FO is the index signal carrier frequency that becomes the first index signal, and ±Fs is the upper side wave and lower side wave generated by frequency modulating the first index signal FO. This side wave can be considered to correspond to the second index signal.

That is, when the modulation index is relatively small, for example, when frequency modulation is performed at about 0.5 as in this embodiment,
Since the level of higher-order side waves is small, it is effectively
As shown in the spectrum diagram in the figure, it is sufficient to consider FO and ±Fs. As is clear from FIG. 7, the phase of the color carrier frequency Fc is π for one horizontal scanning line interval.
The stripe filter 103 is tilted with respect to the electron beam Eb so as to change by radian, the index carrier frequency FO is set to a repetition frequency 3/2 times the color carrier frequency Fc, and the charge of the index signal is Since the transparent conductive electrodes separated into comb-like shapes for generating the pattern are tilted at the same angle as the stripe filter 103, the phase of the index carrier frequency FO changes by 3/2π radian for each horizontal scanning line. ing. Therefore, if the vertical correlation is taken every two horizontal scanning lines, the phase of the color carrier frequency Fc changes by 2π radians,
The phase of the index carrier frequency changes by 3π radians, making it possible to separate the sidebands of the color carrier signal from the index signal. In this embodiment, a color signal and an index signal having different carrier frequencies are separated in frequency space using a bandpass filter, etc., and the sidebands and index signals of the color signal are separated by using vertical correlation as explained above. Signal interference can be reliably removed, and therefore index signals and color signals can be reliably separated. The index signal separated in this way is subjected to FM detection,
R,. G. A second index signal containing position information for each color of the B stripe filter 103 is extracted.

Further, the first index signal, which is the carrier frequency of the second index signal, is separated by a bandpass filter having a relatively narrow bandwidth, and its frequency is converted to obtain an index signal for synchronous detection of the color signal. At that time, by counting down the frequency based on the position information included in the second index signal, reliable frequency conversion can be realized. As yet another method, it is also possible to frequency-multiply the extracted second index signal as it is and use it as an index signal for synchronously detecting a color signal. The outline of the signal processing circuit in this embodiment will be explained below with reference to FIG. 10, FIG. 8, and FIG. 9.

In FIG. 10, reference numeral 101 denotes an imaging device as shown in FIG. 4, from which a mixed signal of a video signal and an index having a frequency spectrum as shown in FIG. Amplified and low pass filter 124
, a bandpass filter 125, and a 2H delay device 131, respectively. The low-pass filter 124 cuts off the color signal and the index signal to obtain a luminance signal (Ys in FIG. 9), and the band-pass filter 125 cuts off the color signal (Ys in FIG. 9).
Fc) shown in FIGS. 8 and 9 is selectively taken out.
The color signal and index signal supplied to the 2H delay device 131 are delayed by two horizontal scanning periods, and the subtraction circuit 139 takes the difference between the color signal and the undelayed signal, thereby separating the sideband of the color signal and the index signal. and is supplied to bandpass filters 132 and 135.

The index signal separated using the vertical correlation of the image signal has a relatively wide bandwidth (as shown by Fs in FIG. 9).
The frequency-modulated index signal shown in FIG. 8 MF thus obtained is supplied to a limiter and FM detector 136, and is output as a second index signal (Fs in FIG. 8). Detected. On the other hand, the narrow bandwidth that does not include both side waves of FSlfs (
Bandpass filter 132 (denoted as FO in FIG. 9)
, only the index carrier signal (FO in FIG. 8) having the first index frequency is selectively extracted.
/3 frequency counter 133, 2MHZ
is counted down to. Here, the second index signal (Fs in FIG. 8) subjected to FM detection is supplied to the reset pulse generator 137 and subjected to waveform conversion, and then applied to the reset terminal of the frequency counter 133, where it becomes the first index signal. On the other hand, R,. G. ．． To enable reliable countdown of a first index signal while giving position information of each color of a B stripe filter. Further, the first index signal counted down at 2 MHZ is converted to twice the frequency (the eighth one) by the frequency multiplier 134.
FO×2/3) in the figure, and becomes an index signal having the same frequency as the 4 MHZ color carrier frequency.
The index signal converted to 4MHZ is sent to the phase shifter 13.
0,129, and is supplied to color signal synchronous detectors 126, 127, 128 as shown in FIG. 10, and the color signal obtained by a bandpass filter 125 is synchronously detected.
R-Y. G-Y. Obtain a B-Y color difference signal.

The color difference signal detected in this way is passed through a low-pass filter 124.
The matrix circuit 138 is supplied with the luminance signal from the matrix circuit 138, and the three primary color signals ER, EG
, EB are obtained, and by using these three primary color signals and the luminance signal from the low-pass filter 124, it is possible to create an NTSC color television signal or a color television signal according to other systems. Furthermore, in this embodiment, as a means of increasing the resolution of the luminance signal, as mentioned at the beginning, the color signal band and part of the luminance signal band are shared by utilizing the fact that the phase of the color carrier frequency is inverted for each horizontal scanning line. The color signal and the luminance signal are separated by using a comb-shaped filter using a delay circuit having a delay time of one horizontal scanning period. It is also possible.

Further, in the above embodiment, the case where the index signal is electrically written by separating the transparent conductive electrode as the means for generating the index signal has been explained, but in the present invention, in separating the index signal and the color signal,
There is no need to electrically change the charge pattern of the index signal generated on the photoelectric conversion surface, as is done in the conventional example mentioned at the beginning, and processing is performed using the charge pattern of the index signal that is always fixed. Therefore, it is also possible to generate an index signal by optical means. Furthermore, the idea of the present invention is not limited to the case where an index signal is generated by optical means, but is also extremely effective in a method in which an electrode intended for generating an index signal is provided near the cathode side of the photoelectric conversion surface. It can be used for

Furthermore, in the embodiment, a case has been described in which a rectangular wave signal as shown in FIG. It is possible to extract signals of various waveforms as the second index signal.

Furthermore, although the present embodiment has been described with respect to a single tube camera using one image pickup tube, it goes without saying that the present invention can also be effectively applied to a two tube color camera.

As is clear from the above embodiments, according to the present invention, a stable index signal can always be obtained regardless of the subject, and it is also possible to reduce afterimages, which have been a major problem with color imaging devices using vidicon. Accordingly, it is possible to provide a color imaging device using a phase separation method.

Furthermore, by giving a difference between the repetition frequency of the index signal and the repetition frequency of the color signal, it is possible to separate the index signal and the color signal by means of a filter having spatially different frequency bands.
Even for images with little vertical correlation, index signal disturbances due to miscorrelation are unlikely to occur.

Furthermore, by introducing the concept of frequency modulation of the index signal when converting the frequency of the index signal, the second index signal necessary for frequency conversion can be stably obtained. be able to.

[Brief explanation of drawings]

The drawings show a color imaging device according to an embodiment of the present invention, and FIG. 1 is an equivalent circuit diagram of an image pickup tube, FIG. 2 is an electron beam line impedance characteristic diagram, FIG. 3 is an index generation process diagram, and FIG. The figure is a diagram of the main parts of this device, Figure 5 is a partial operational waveform diagram, Figures 6 and 7 are detailed diagrams of the target section, Figure 8 is a signal waveform diagram, and Figure 9 is a diagram of the video signal. A frequency spectrum diagram of a signal in which the index signal is mixed, and FIG. 10 is an electrical system diagram. 101... Image pickup tube, 103... Strive filter, 105a, 105b... Transparent conductive electrode, 108... Cathode bias voltage source, 11
3... Transformer, 109... Constant voltage power supply, 112... Preamplifier, 132, 135...
... Bandpass filter, 136 ... FM detector, 137 ... Reset pulse generator, 13
3... Frequency counter.

Claims (1)

[Claims] 1 means for obtaining a mixed signal of a color signal and an index signal; means for extracting a first index signal from the mixed signal; means for FM detecting the index signal to obtain a second index signal; means for associating the first index signal with the position information of each color in the stripe filter based on the index signal and correcting it to the same frequency as the color signal by transmitting it; A color imaging device equipped with means for synchronous detection.