JPS6412157B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a recording and reproducing device for color video signals, and in particular, it compresses the time axis of a specific color difference signal out of two types of color difference signals and converts it into the other color difference signal. This multiplexed signal is time-division multiplexed and multiplexed onto the luminance signal, and this multiplexed signal is recorded on a recording medium. During playback, one time-axis compressed color difference signal is time-axis expanded and returned to the original time axis, and then simultaneously The present invention relates to a recording and reproducing device that generates a reproduced color video signal together with other transmitted color difference signals and luminance signals.

Prior Art Current color video signal recording and reproducing devices (e.g.
Recording and reproducing devices, which are the mainstream among VTRs, separate a luminance signal and a carrier color signal from a standard format (NTSC, PAL, or SECAM format) composite color video signal, and the luminance signal is frequency-modulated to receive the signal. A frequency modulated wave is used, and the carrier color signal is frequency-converted to a low frequency band to become a low-frequency converted carrier color signal, which is then frequency-division multiplexed to the frequency-modulated wave and recorded. During playback, the signal processing is reversed to that during recording. to obtain a reproduced composite color video signal that complies with the original standard method.
It is well known that this is a recording and reproducing apparatus using a so-called low frequency conversion recording and reproducing method. The recording and reproducing apparatus using such a low frequency conversion recording and reproducing method is particularly suitable for application to consumer VTRs, which have a relatively narrow band for recording and reproducing, since the band of the luminance signal can be arbitrarily selected. It is less susceptible to fluctuations in the reproduction time axis of a VTR, and only the luminance signal passes through the FM modulation/demodulation system, and a pilot signal is not recorded or reproduced to eliminate fluctuations in the time axis of the reproduced low-frequency conversion carrier chrominance signal. It has advantages such as less interference, and furthermore, the frequency modulated luminance signal acts like a high frequency bias and the carrier color signal can be recorded with good linearity.

However, on the other hand, the above-mentioned recording and reproducing apparatus using the low-frequency conversion recording and reproducing method frequency-division multiplexes the frequency-modulated luminance signal and the low-frequency conversion carrier chrominance signal and records and reproduces them on a magnetic tape using a non-linear transmission system. Since moiré occurs and the recording/reproducing band is limited, the band of the frequency-modulated luminance signal (in other words, the band of the luminance signal) is equal to the band of the low-frequency conversion carrier color signal.
must be narrowed, and the band of the wideband color difference signal (for example, the I signal of the I signal and Q signal) of the two types of color difference signals that are modulation signals of the carrier color signal is limited by low-pass conversion. The low-pass conversion carrier color signal is a balanced modulated wave when recording the NTSC or PAL color video signal, and it is recorded with a bias by the frequency-modulated luminance signal.
Due to uneven contact between the tape and the head, AM noise occurs in the playback low-frequency conversion carrier color signal, deteriorating the S/N (signal-to-noise ratio). In recording and reproducing apparatuses that use the so-called azimuth recording and reproducing method, in which video tracks are recorded and formed at different azimuth angles without guard bands, the azimuth loss effect is not sufficient for low frequencies, so the reproduction signal Because the low frequency conversion carrier color signal of the adjacent track is mixed in as a crosstalk component, the phase of the color subcarrier frequency of the low frequency conversion carrier color signal of the NTSC or PAL system is changed during one horizontal scanning period during recording and playback. (for example, Japanese Patent Publication No. 56-9073, Japanese Patent Publication No. 55-32273)
However, there were problems such as the need for crosstalk countermeasure processing, such as reversing the phase of only one of the low-frequency conversion carrier color signals of adjacent video tracks every 1H.

Furthermore, when recording and reproducing SECAM system color video signals using the above-mentioned azimuth recording and reproducing system recording and reproducing apparatus, the carrier color signal is a frequency modulated wave, so the above-mentioned crosstalk countermeasures cannot be applied. , if horizontal synchronizing signal recording positions are aligned and recorded in the direction perpendicular to the longitudinal direction of adjacent video tracks (track width direction) (so-called H-aligned recording), and if the sideband is also included, the recording speed is 2MHz.
The modulation signal components of the low-pass conversion carrier color signals obtained by counting down the carrier color signals, which are frequency-modulated waves in a wide band as described above, are approximately the same (that is, the color difference signal components of the same type). If you record it and play it back (for example,
Please refer to Publication No. 26875 if necessary)
In this case, the frequency reproduced as crosstalk from adjacent tracks of the above low-pass conversion carrier color signal has a correlation between the color video signal components at one field interval, and the modulation signal components are arranged side by side. Since it is recorded, the frequency is approximately the same as the frequency of the low frequency conversion carrier color signal of the reproduction track,
Since the frequency of the beats generated by both signals is close to zero, the influence of crosstalk can be almost eliminated.

However, when playing back a magnetic tape with a track pattern that is not recorded in H alignment,
Because the carrier frequencies of the low-frequency conversion carrier color signals in the SECAM system are different, the beat frequency due to crosstalk from adjacent tracks extends to the high frequency range, which appears as noise on the playback television screen. There was a problem in that the azimuth recording/reproducing method could not be applied.

On the other hand, with recent dramatic advances in semiconductor technology, precision processing technology, and small component technology, it has become possible to improve the image quality of recording and reproducing devices and to make the devices smaller and lighter. Reducing the cassette size and drum diameter has a major impact on making devices smaller and lighter, and in order to secure the necessary recording time for small cassettes, it is necessary to slow down the tape running speed. In order to obtain high image quality in lightweight recording and reproducing apparatuses, a new recording and reproducing method other than the above-mentioned low frequency conversion recording and reproducing method has come to be required.

Therefore, various recording and reproducing methods have been proposed to meet the above requirements, one of which is to time-base compress the two types of color difference signals obtained by FM demodulating the carrier color signal, and also compress the luminance signal. Compress the time axis,
These signals are time-division multiplexed, this time-division multiplexed signal is frequency-modulated, and recorded on a recording medium. During playback, signal processing is performed in the opposite manner to that during recording, and the original standard color video signal is reproduced. There was a recording and reproducing device configured to obtain a reproducing output (see, for example, Japanese Patent Laid-Open No. 53-5926). This recording/reproducing device takes into consideration the difference between the bands of the luminance signal and the color difference signal, and is designed to transmit the color difference signal, which is a signal with a narrower band, within the horizontal blanking period. The time axis of one color difference signal transmitted within the 1H period is compressed to approximately 20% of the 1H period, and the luminance signal is compressed in the same bandwidth as the time axis compressed color difference signal, which is advantageous from the viewpoint of bandwidth utilization. Approximately 80% of the 1H period to account for
The two color difference signals are time-division multiplexed as line-sequential signals that are transmitted alternately every 1H, and this signal is supplied to the FM modulator, and the output of this FM modulator is A recording/reproducing method in which signals are recorded on magnetic tape, etc., and during playback, signal processing is performed in the opposite manner to that during recording to obtain a reproduced color video signal (hereinafter referred to as the "timeplex" method). It was structured based on.

FIG. 1 shows an example of the signal waveform of the above-mentioned time division multiplexed signal. For example, in a PAL or SECAM composite color video signal with a field frequency of 50Hz and 625 scanning lines, 1H is 64μs, the horizontal blanking period is 12μs, and the remaining 52μs video period is used to control luminance. The signal and the carrier color signal are transmitted (excluding the color burst signal), of which the luminance signal is compressed in time to approximately 80% of the period of 64 μs.
In addition, the carrier color signal is demodulated into two types of color difference signals, each of which is time-axis compressed in a period of about 20% of 64 μs. The time-axis compressed luminance signal and the time-axis compressed color difference signal are shown in Figure 1. time-division multiplexed, and
The time-base compressed color difference signal is transmitted line-sequentially. Also, as shown in Figure 1, both time axis compressed signals are
Transmission takes about 50μs to 60μs, but 1H period is 64μs
During the remaining period (blanking period), the horizontal synchronizing signal H.SYNC and the reference level of the color signal are transmitted.

According to the timeplex method for transmitting such time-division multiplexed signals, there is no period during which the luminance signal and color difference signal are transmitted simultaneously. There is no mutual interference or moiré between the luminance signal and the color difference signal, which can occur when transmitting the luminance signal and the color difference signal by band-sharing multiplexing, and it is also compatible with any of the NTSC, PAL, and SECAM color video signals. In this case, even if tracks are recorded and reproduced on tracks that are not aligned in H by an azimuth recording/reproduction system, the time-division multiplexed signal on adjacent tracks may cause a high-frequency carrier wave with a large azimuth loss effect to be Since it is recorded in the form of a frequency-modulated wave signal obtained by modulation, almost no crosstalk occurs due to the azimuth loss effect, eliminating the need for the above-mentioned crosstalk countermeasures and providing high-quality reproduced images. It will be done.

Furthermore, the above-mentioned time-domain compressed luminance signal and time-domain compressed color difference signal in the timeplex method have an energy distribution in which the energy is large in the low frequency band and small in the high frequency band. Since the signal format is suitable for The reproduced image quality can be significantly improved compared to that of the low frequency conversion recording and reproducing method.

Problems to be Solved by the Invention However, the above-mentioned timeplex method has the following problems:
The luminance signal, which has a much wider band than the color difference signal, was also compressed in time and transmitted in the same way as the color difference signal.
This requires a time-base compression circuit for luminance signals with a complex and sophisticated configuration using a high sampling frequency, resulting in a problem that the circuit configuration of the entire device becomes complicated and expensive. In addition, the above-mentioned timeplex method requires processing to separate the horizontal synchronization signal from the luminance signal, insert it at a predetermined position, and transmit it, making the handling of the horizontal synchronization signal relatively complicated. When transmitting a Q signal and a Q signal, the time axis compression ratio is the same for both signals, so the broadband I signal
There was a problem that the band was limited to the signal level.

Therefore, the present invention transmits only one of the two types of color difference signals, which has a band narrower than the band of the other color difference signal or has a similar band, within the horizontal blanking period of the luminance signal. A time division multiplexed signal in which the signal obtained by time axis compression is time division multiplexed within the horizontal blanking period of the other color difference signal, and the phase is inverted every horizontal scanning period (1H). The signal is multiplexed with a luminance signal that is not subjected to time-axis compression and recorded. During playback, a comb filter is used to separate the luminance signal and time-division multiplexed signal from the reproduced signal, and the time-axis compressed signal is recorded. It is an object of the present invention to provide a color video signal recording and reproducing device that solves all of the above-mentioned problems by expanding the time axis of one color difference signal and returning it to the original time axis.

Means for Solving the Problems The present invention provides a second color difference signal which has a band equal to or less than the band of the first color difference signal.
a time-base compression circuit for time-base compressing at least a signal portion of the effective horizontal scanning period and a signal portion of the burst level transmission period of the color difference signal into a period within the horizontal blanking period of the luminance signal; The time-axis compressed color difference signal is time-division multiplexed within an interval corresponding to the horizontal blanking period of the first color difference signal, and
a time division multiplexed signal generation circuit that obtains a time division multiplexed signal whose phase is inverted for each horizontal scanning period; and a first mixing circuit that multiplexes the time division multiplexed signal and a luminance signal that is not subjected to time axis compression. , means for recording the output multiplexed signal of the first mixing circuit on a recording medium and reproducing the same; and a comb for separately separating and outputting the time division multiplexed signal and the luminance signal from the reproduced multiplexed signal. removing the phase inversion for each horizontal scanning period based on a switching signal generated from a horizontal synchronization signal in the reproduced luminance signal from the comb filter, and a reproduction time division multiplexed signal from the comb filter; switch circuit means for separating and outputting a reproduced signal of the first color difference signal and a second color difference signal compressed in the time axis; a time axis expansion circuit for obtaining a reproduction signal of the second color difference signal which is returned to the original time axis by time axis expansion of the color difference signal; a circuit that generates a carrier color signal conforming to the standard television system; and a second mixing circuit that multiplexes the carrier color signal and the reproduced luminance signal from the comb filter, respectively, and outputs the multiplexed signal as a reproduced color video signal. One embodiment of the circuit will be described below with reference to FIG. 2 and the subsequent drawings.

Embodiment FIG. 2 shows a block system diagram of a recording system of an embodiment of the apparatus of the present invention. This embodiment is an example applied to a helical scan VTR based on the NTSC standard. In the figure, the NTSC color video signal input to input terminal 1 is supplied to low-pass filter 2 and band filter 3, respectively. The filter 2 separates the luminance signal, and the bandpass filter 3 separates the carrier color signal. Here, for convenience of explanation, input
Assuming that a color bar signal as shown in Figure 3A is received as an NTSC color video signal,
A luminance signal E _Y having a waveform as shown in FIG. 2B is taken out from the low-pass filter 2. In addition, in Figure 3A,
CB ₁ , CB ₂ , and CB ₃ indicate color burst signals.

The carrier color signal taken out from the bandpass filter 3 is a modulated wave obtained by performing carrier suppression quadrature two-phase amplitude modulation on the color subcarrier frequency 3.579545 MHz using two types of color difference signals, the I signal and the Q signal. 4
and demodulated into an I signal E _I and a Q signal E _Q , respectively. Here, the luminance signal E _Y and the color difference signals E _I and E _Q are expressed by the following equations, as is well known.

E _Y =0.299E _R +0.587E _G +0.114E _B E _I =-0.27 (E _B −E _Y ) +0.74 (E _R −E _Y ) E _Q =0.41 (E _B −E _Y ) +0.48 ( _ER −E _Y ) However, in the above formula, E _R , E _G and E _B are red,
The gamma corrected primary color signals of green and blue are shown.

The above color difference signal E _I is a baseband signal that occupies a band of about 1.5 MHz, and when the color bar signal is input, it has a waveform as shown in Figure 3C, and the above color difference signal E _Q occupies a band of about 0.5 MHz. This is an occupied baseband signal, and when a color bar signal is input, it becomes a signal with a waveform as shown in FIG. In addition, Fig. 3C
In the middle, c ₁ and c ₂ indicate the burst level, which is a DC level that is the color reference of the color difference signal E _I , and in the same figure D
In the figure, d ₁ and d ₂ indicate the burst level of the color difference signal _EQ . When the burst level is 100% white,
c ₁ and c ₂ are each approximately 0.11, and d ₁ and d ₂ are each approximately −0.17.

As will be described later, this embodiment aims to minimize the quality deterioration of the reproduced image in the case of a color video signal in which the similarity of video information in the vertical direction of the screen, that is, the correlation in the vertical direction (or line correlation) is small. The color difference signal with the smaller band is
The signal portion of at least the effective horizontal scanning period and the burst level transmission period of E _Q (Q signal) is compressed in time to 1/5. That is, of the output color difference signals E _I and E _Q of the decoder 4, the color difference signal E _Q is supplied to the 1/5 time axis compression circuit 6, and here, the color difference signal E Q of the period T ₁ of the color difference signal E _Q shown in FIG. The time axis of the signal portion and the period T ₂ before and after the signal portion including the burst level transmission period is compressed to 1/5. The above period T ₁
is from 1H (=63.5555μs) to 10.5μs which is the horizontal blanking period (hereinafter also referred to as "H blanking")
The period after subtracting 11.4 μs is 53.0555 μs to 52.1555 μs, which is equal to the effective horizontal scanning period.

Note that the time axis compression circuit 6 is a charge transfer element such as a charge coupled device (CCD),
It can be configured with a digital circuit consisting of an AD converter, random access memory (RAM), and a DA converter.

In this way, from the 1/5 time axis compression circuit 6,
A time-base compressed color-difference signal E _{Q ′} is obtained by compressing the signal part of the sum of the effective horizontal scanning period T ₁ and the period T ₂ including the burst level transmission period of the color-difference signal E _Q to 1/5. is supplied to the synthesis circuit 7,
Here, the decoder 4 time-division multiplexes the other color difference signal E _I passed through the burst removal circuit 5 into an interval corresponding to the horizontal blanking period. If burst levels c ₁ and c ₂ exist during the horizontal blanking period of the color difference signal E _I , the burst removal circuit 5 overlaps with the time axis compressed signal E _Q and cannot be separated by the regenerating thread described later. This is a circuit for removing levels c ₁ and c ₂ .

Here, the above periods T ₁ and T ₂ of the color difference signals E _I , _EQ
The signal level is constant during the period excluding
Furthermore, since the signal portion of the color difference signal E _Q in the period other than the period T ₁ +T ₂ is not outputted from the 1/5 time axis compression circuit 5, the output signal of the combining circuit 7 is as shown in FIG. As shown in FIG. 2, the signal of the effective horizontal scanning period of the color difference signal E _I and the time-axis compressed color difference signal E _Q ' are synthesized in time series to form a time division multiplexed signal within the 1H period. In addition, the above time-axis compressed color difference signal
Since E _Q ′ is a signal obtained by compressing the time axis to 1/5 of the color difference signal E _Q with a band of approximately 0.5 MHz, its band is approximately
2.5MHz (=0.5MHz÷(1/5)). Therefore, the band of the output time division multiplexed signal of the synthesis circuit 7 is approximately 2.5M
Hz, and this is a band that can be transmitted with a sufficiently high S/N ratio even on a general home VTR, which has a relatively narrow recording and playback band, so the frequency characteristics of the color difference signal deteriorate due to the narrow recording and playback band. No phenomenon occurs. Furthermore, the color difference signal E _I in the time division multiplexed signal is not subject to any band limitation and can be recorded and reproduced at its original band of approximately 1.5 MHz.

In this way, the time-division multiplexed signal as shown in FIG. 8 is supplied to the terminal 8b.

On the other hand, the luminance signal E _Y described above is supplied to the horizontal synchronization signal separation circuit 10, where the horizontal synchronization signal is separated and extracted, and then supplied to the 1/2 frequency divider 11. As a result, a 2H period symmetrical rectangular wave that is phase-synchronized with the horizontal synchronization signal is extracted from the 1/2 frequency divider 11, and this rectangular wave is applied to the switch circuit 8 as a switching signal, causing the switch circuit 8 to 1H
Switching control is performed such that the terminal 8a is in the input signal selection output state for a period, and the terminal 8b is in the input signal selection output state for the next 1H period, so that the connection is alternately switched every 1H.

Therefore, as shown in FIG. 3F, the output signal of the switch circuit 8 is a time-division multiplexed signal obtained by alternately inverting the phase of the time-division multiplexed signal shown in FIG. The 1H period in which E _I and the time-domain compressed color difference signal E _Q ′ are synthesized in time series, and the phase-inverted signals E _I and _Q ′ of the color difference signal E _I and the time-domain compressed color difference signal E _Q ′ are This results in a time division multiplexed signal in which sequentially synthesized 1H periods appear alternately. The time-division multiplexed signal shown in FIG. 3F taken out from this switch circuit 8 is supplied to the mixing circuit 13, where it is taken out from the low-pass filter 2 via the 1H delay circuit 12 shown in FIG. 3B. , is mixed with the luminance signal E _Y that has not been subjected to time axis compression, and is converted into a multiplexed signal as shown in FIG. Note that the 1H delay circuit 12 is provided to correct a delay of at least 1H caused by the time axis compression circuit 6.

The recording signal processing circuit 14 is a circuit that performs signal processing suitable for magnetic recording and reproduction on input multiplexed signals.
It has a circuit configuration in which a pre-emphasis circuit, a white/dark clip circuit, a frequency modulation circuit, etc. are connected in cascade. Predetermined signal processing is performed by the recording signal processing circuit 14, for example, as shown in FIG.
An FM signal obtained by frequency modulating the carrier wave with the multiplexed signal shown in FIG.

Next, to explain the recycled yarn, FIG. 4 shows a block system diagram of the recycled yarn of an embodiment of the apparatus of the present invention. In the figure, a reproduced FM signal extracted from a magnetic tape (none of which is shown) by a rotary head enters an input terminal 16, and this reproduced FM signal is supplied to a reproduced signal processing circuit 17, where the FM After being demodulated, de-emphasis characteristics are added to the third
The signal is extracted as a reproduced multiplexed signal as shown in Figure G. This reproduced multiplexed signal is supplied to an adder circuit 18, a subtracter circuit 19 and a 1H delay circuit 20, and further
The reproduced multiplexed signal delayed by 1H by the 1H delay circuit 20 is supplied to the subtraction circuit 19, and is also supplied to the addition circuit 18 through the switch circuit 21. The above circuits 18, 19, 20, and 21 constitute a comb filter, and the luminance signal in the reproduced multiplexed signal is taken out from the addition circuit 18, and the phase is inverted every 1H from the subtraction circuit 19 as shown in FIG. 3F. The time-division multiplexed signal is extracted.

This will be explained in more detail. Now A,
There are two signals called B, and one signal B is 1H.
The signal obtained by adding the above signal A to the signal that is inverted and transmitted in the order of B,,B,,...
In the nth line (horizontal scanning line), A+B, n+
A+ on the 1st line, A+B on the n+2nd line, A+ on the n+3rd line,...
It is transmitted as follows. When this adder circuit is passed through a 1H delay circuit, its output signal is A+B on the n+1st line, and A+ on the n+2nd line.
In the B, n+3rd line, A+B, . . . are extracted in this order. Therefore, the above-mentioned 1H delay circuit, its input addition signal, and output delay signal are respectively added. A signal 2A is taken out on all lines from a comb filter consisting of an adder circuit.
Furthermore, from the comb filter consisting of the above 1H delay circuit and a subtraction circuit that subtracts the output delay signal from the input addition signal, 2,
The signals transmitted in the order of 2B on the n+2nd line, 2 on the n+3rd line, . . . , that is, signals obtained by inverting the phase of the signal 2B every 1H are extracted.

Therefore, in this embodiment, the above signal A is the luminance signal E _Y , and the signal B is the 1H signal shown in FIG. 3E.
This is a time division multiplexed signal without phase inversion. Therefore, from the adder circuit 18, the luminance signal E _Y
is taken out, and the above-mentioned time division multiplexed signal is taken out from the subtraction circuit 19 with its phase inverted every 1H (that is, in a waveform as shown in FIG. 3F).

However, the above explanation is based on an ideal case where there is a perfect vertical correlation between the luminance signal _E The luminance signal is combined with a time division multiplexed signal, that is, the vertical differential component of the color difference signal (for example, the time division multiplexed signal of the nth line and the
- signal of the sum of the phase inverted signal of the time division multiplexed signal of the 1st line, signal of the sum of the phase inverted signal of the time division multiplexed signal of the n+1th line and the time division multiplexed signal of the nth line, etc.) Conversely, the color difference signal (time division multiplexed signal) contains the vertical differential component of the luminance signal _E difference signal) will be mixed in.

Furthermore, unlike the present invention, if two types of time-axis compressed color difference signals are time-division multiplexed within a 1H period,
In addition, if the time division multiplexed signal whose phase is inverted every 1H is multiplexed with the luminance signal and recorded on a recording medium, and this is to be reproduced, the time-axis compressed color difference signal multiplexed within the 1H period. Since there is no correlation between the luminance signal and the luminance signal, the influence of the vertical differential component mixed in from one of the luminance signal and color difference signal to the other may become more noticeable.

To explain this further on the screen, for example, among the color difference signals E I and E _Q that constitute a color video signal that displays, for example, a circular color image 38 on the playback screen 37 of width L in _FIG . E _Y compresses the time axis by 3/4, and E _Q compresses the time axis by 1/4 and both signals.
If time division multiplexing is performed within a 1H period, this time division multiplexed signal is recorded, and it is played back as it is without further time axis expansion, the playback screen 3 will appear as shown in Figure 5.
7, for example, the color difference signal is displayed on the left side of the screen with a width of L/4.
Color image 39 by E _Q is displayed and the remaining width
A color image 40 based on the color difference signal E _I is displayed on the 3L/4 screen portion.

In addition, when recording and reproducing the luminance signal multiplexed with the above time division multiplexed signal without time axis compression,
The reproduced image based on the luminance signal becomes a black and white image having the same shape and size as the original circular color image and showing only brightness, as shown at 41 in FIG. Therefore, the phase of the above time-division multiplexed signal is inverted every 1H, multiplexed with the luminance signal, and recorded, and during playback, a comb filter is used to separate and extract the luminance signal and time-division multiplexed signal from the reproduced signal. The two types of time-axis compressed color difference signals are each expanded back to the original time axis, and a carrier color signal is generated from the two types of reproduced color difference signals obtained by this and mixed with the reproduced luminance signal. The playback screen for displaying the playback color image of the recording/playback device configured to obtain the playback color video signal is, as shown at 42 in FIG. 5, a color image 4 having the same shape and hue as the original color image 38.
In addition to 3, there are linear images as shown by broken lines 44 and 45 due to the mixed component of the vertical differential component of the color difference signal to the luminance signal, and a dashed-dotted line due to the mixed component of the vertical differential component of the luminance signal to the color difference signal. Line-shaped images as shown in 46 and 47 end up appearing.

Here, the above-mentioned images 44 and 45 are the outlines of the color images 39 and 40, and are visible as elliptical rings with different brightness, and the images 46 and 47 are visible as colored lines, and also have vertical correlation. Areas where there is no image (upper and lower parts of the image) appear thicker. One of the objects of the present invention is to significantly reduce such unnecessary images 44-47. Note that the image 46 is a color image 38
The image 47 is the outline of the image part displayed in a width of 3L/4 on the right side of the screen, expanded by 4/3 on the time axis, and the other image 47 is a width of L/4 on the left side of the screen of the color image 38. This is the outline of an image portion that has been temporally expanded four times as much as the image portion displayed in .

Returning to FIG. 4 again, the subtraction circuit 19
The time division multiplexed signal taken out from the switch circuit 22 is supplied to the terminal 22a of the switch circuit 22, and after being phase-inverted by the inverter 23, the time division multiplexed signal is supplied to the terminal 22a of the switch circuit 22.
is supplied to the terminal 22b.

On the other hand, the reproduced luminance signal taken out from the addition circuit 18 is supplied to the horizontal synchronization signal separation circuit 24,
Here, the horizontal synchronizing signal is separated and extracted and then supplied to the switching pulse generation circuit 25. The switching pulse generation circuit 25 is supplied with the above-mentioned reproduction horizontal synchronization signal and a reproduction color difference signal E _Q taken out from a 5/1 time axis expansion circuit 28, which will _be described later. , and it is the normal value (white 100 as mentioned above)
A symmetrical rectangular wave with a period of 2H is generated with a polarity of approximately -0.17) when % is 1, and is phase-synchronized with the reproduced horizontal synchronizing signal, and this symmetrical rectangular wave is used as a switching pulse to be applied to the switch circuit 22. Output to. As a result, the switch circuit 22 is alternately connected to the terminals 22a and 22b every 1H, and the reproduced time division multiplexed signal from which phase inversion has been removed every 1H is output from the output terminal as shown in FIG. 3E. The signal is taken out and supplied to the signal separation circuit 26 at the next stage.

The switch circuit 26 switches the output pulse of the H blanking pulse generation circuit 27, which generates the H blanking pulse at a predetermined level only during the period corresponding to the horizontal blanking period of the reproduced luminance signal, based on the reproduced horizontal synchronization signal. The period corresponding to the horizontal blanking period is supplied as a pulse to terminal 26.
The terminal 26b is connected to the terminal 26b during the other periods. As a result, the switch circuit 26 outputs the reproduced signal of the color difference signal E _I from the terminal 26a and supplies it to the encoder 29 through the 1H delay circuit 30, and separates and outputs the time axis compressed color difference signal E _Q ' from the terminal 26b. 5/1 is supplied to the time axis expansion circuit 28.

The 5/1 time axis expansion circuit 28 expands the time axis of the input signal _EQ ' by five times and outputs a reproduced signal of the color difference signal _EQ which has been restored to its original time axis. Since this reproduced color difference signal E _Q includes a burst level, it is supplied to a switching pulse generation circuit 25 where the burst level is detected, and is also supplied to an encoder 29. encoder 2
9 is supplied with reproduced color difference signals E _I and E _Q , respectively, from which a carrier color signal conforming to, for example, the NTSC system is generated and outputted to the mixing circuit 34 . Note that since the burst level has been removed from the reproduced color difference signal E _I during recording, a color burst signal is generated by an oscillator or the like in the encoder 29. Further, the 1H delay circuit 30 is a circuit for time-aligning the reproduced color difference signal E _I with the reproduced color difference signal E _Q taken out from the time axis compression circuit 28.

By the way, the switch circuit 21 is a circuit that passes or cuts off the input signal, and is a circuit that passes or cuts off the input signal. A V blanking pulse of a predetermined level is applied as a switching pulse during a period corresponding to an erase period (V blanking period). As a result, the switch circuit 21 is turned off during the vertical blanking period to cut off transmission of the output signal of the 1H delay circuit 20 to the addition circuit 18, and is turned on during periods other than the vertical blanking period. Pass the above input signal.

The reason why the switch circuit 21 is provided here is that, as is well known, the phase of the vertical synchronizing signal is shifted by H/2 between odd and even fields due to interlaced scanning. This is to prevent the vertical synchronization signal of the reproduced luminance signal E _Y taken out from the adder circuit 18 from being disturbed due to the H/2 phase shift of the vertical synchronization signal. Therefore, the luminance signal comb filter consisting of the adder circuit 18, 1H delay circuit 20 and switch circuit 21 is as follows:
It is inactive during the vertical blanking period, and during this period, the adder circuit 18 outputs the reproduced multiplexed signal from the reproduced signal processing circuit 17 as it is. Note that in the reproduced multiplexed signal, no color difference signal originally exists during its vertical blanking period (however, a burst level exists from the time following the equalization pulse after the vertical synchronization signal).

The reproduced luminance signal taken out from the adder circuit 18 is delayed by 1H by a 1H delay circuit 23 and then supplied to a mixing circuit 34. The 1H delay circuit 33 is provided for time alignment with the reproduced color difference signals E _Q and E _I , which are delayed by 1H by the time axis expansion circuit 28 and the 1H delay circuit 30. Mixing circuit 3
4 multiplexes the reproduced luminance signal and the reproduced carrier color signal to generate a reproduced color video signal substantially compliant with the NTSC system, and outputs this signal to the output terminal 35.

As described above, according to this embodiment, color images can be transmitted without band-limiting the I signal E _I and the Q signal E _Q , and in a band that can be sufficiently transmitted even on a VTR having a narrow recording/playback band. Signals can be recorded and reproduced in the form of a multiplexed signal of a time division multiplexed signal and a luminance signal. Further, in this embodiment, since both the color difference signal E _I and the luminance signal E _Y are not subjected to time axis compression, a correlation exists. Therefore, even if the image has little vertical correlation, the luminance signal
The vertical differential components that mix from one of E _Y and the color difference signal E _I to the other and from the other to one are not so noticeable.

Furthermore, the time-domain compressed color difference signal E _Q ' is multiplexed within the horizontal blanking period, but since the horizontal synchronization signal has perfect vertical correlation, the luminance signal E _Y
No leakage of the vertical differential component from to the color difference signal E _Q ' occurs. On the other hand, leakage of the vertical differential component from the color difference signal E _Q ′ to the luminance signal E _Y occurs, but since the color difference signal E _Q ′ is multiplexed within the horizontal blanking period, the above Noise due to leakage also occurs within the horizontal blanking period, so the noise does not appear on the playback screen. Note that a part of the color difference signal E _Q ′ may be slightly multiplexed during the video period, but even in that case, noise due to leakage of the vertical differential component from the signal E _Q ′ to E _Y will not be visible on the playback screen. It is not noticeable because it only appears slightly on the side corner of the screen.

Application Examples The present invention is not limited to the above-mentioned embodiments, and various other application examples are possible. For example, in a recording system, after time-division multiplexing the time-axis compressed color difference signal E _Q to the color difference signal E _I ,
Although the circuit configuration is slightly more complicated, the time-axis compressed color difference signal
After performing phase inversion processing every 1H for each of E _Q and color difference signal E _I , both signals are combined and
Alternatively, a time division multiplexed signal whose phase is inverted each time may be obtained. Similarly, in the reproduction system, the signals E _Q ' and E _I may be separated and then the phase inversion every 1H may be removed.

In addition, the present invention is applicable not only to the NTSC system but also to the PAL system.
It can also be applied to other standard television system color video signals such as the SECAM system and the SECAM system. In this case, the two types of color difference signals _EU and _EV that make up the carrier color signal of the PAL system and the two types of color difference signals D _R and D _B that make up the carrier color signal of the SECAM system are connected to a matrix circuit and a 1H delay circuit. , a changeover switch or the like can be used to convert the signals into color difference signals E _I and _EQ for processing. Furthermore, it is also possible to apply the present invention directly by time-base compressing one of the color difference signals _EU and _EV , or D _R and D _B , each having a band of about 1.3 MHz. However, in terms of transmission band, it is more effective to apply the present invention after converting into E _I and _EQ .

Furthermore, the present invention is not limited to application to VTRs, but can also be applied to devices that record signals on recording media such as disk-shaped magnetic sheets or disks and reproduce them.

Effects As described above, according to the present invention, during recording, only one of the two types of color difference signals, which has a band narrower than the band of the other color difference signal or has a similar band, is used as a luminance signal. The signal obtained by compressing the time axis so as to be transmitted within the horizontal blanking period is time-division multiplexed within the horizontal blanking period of the other color difference signal, and is transmitted every horizontal scanning period (1H). A time-division multiplexed signal whose phase is inverted is generated, the signal is multiplexed with a luminance signal without time axis compression and recorded, and during playback, a comb filter is used to separate the luminance signal and time-division multiplexed signal from the reproduced signal. One color difference signal, which has been separated and time-axis compressed, is time-axis expanded to return it to its original time axis, and this reproduced color difference signal and the other reproduced color difference signal are converted into a desired standard television system (NTSC).
Since the carrier color signal is generated in accordance with the PAL system, PAL system, and SECAM system, it is possible to solve all the problems of the low-frequency conversion recording and reproducing system mentioned above, and also to Since no axis compression or expansion processing is performed, the circuit configuration can be simpler and cheaper than the conventional timeplex method.Furthermore, since the horizontal synchronization signal is transmitted as is, horizontal synchronization Compared to the conventional timeplex method in which a signal is inserted at a predetermined position, processing (handling) of the horizontal synchronization signal is easier. Also, since only the narrowband Q signal of the I signal and Q signal is compressed on the time axis and transmitted within the horizontal blanking period, the band of the I signal is not limited as in the conventional timeplex method. Even in a narrow recording/reproduction band, the I signal and Q signal can be transmitted almost completely. Moreover, in the present invention, since the luminance signal and one of the two types of color difference signals (for example, the I signal) are not compressed on the time axis, a correlation exists, and therefore, there is no correlation in the vertical direction in the image. Even if it is small, the vertical differential component of one signal mixed between the luminance signal and the non-time axis compressed color difference signal can be made less noticeable, and furthermore, the time axis compressed color difference signal can be mixed within the horizontal blanking period. Because they are multiplexed, the vertical differential component of the time-axis compressed color difference signal leaks into the luminance signal, but the resulting noise does not appear on the playback screen, so there is no problem.On the other hand, the horizontal synchronization signal is completely Since there is vertical correlation, the vertical differential component of the luminance signal will not be mixed into the time-axis compressed color difference signal, and from the above, even if there is no vertical correlation in the image, the resulting noise can be significantly reduced. It can be reduced and made less noticeable. Also, since time axis compression and time axis expansion are performed only on one color difference signal (for example, the Q signal), the circuit configuration is simple because only one time axis compression circuit and one time axis expansion circuit are required. Furthermore, since the comb filter is inactive during the vertical blanking period of the reproduced luminance signal, H/2
It has many features, such as being able to prevent the phase of vertical synchronization signals that are different in phase from being disturbed, and being able to record and reproduce signals in a common signal format in standard television systems.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a time division multiplexed signal waveform recorded by the conventional timeplex method, FIG. 2 is a block system diagram showing an embodiment of the recording system of the apparatus of the present invention, and FIG. 3A ~G are time charts for explaining the operation of the block system in FIG. 2, FIG. 4 is a block system diagram showing an embodiment of the reproduction system of the apparatus of the present invention, and FIG. 5 is a time chart for explaining the two types of color difference signals, respectively. FIG. 7 is a diagram illustrating a reproduced image when there is no vertical correlation in the image when a signal obtained by time-division multiplexing the compressed signal and multiplexing a luminance signal on this signal is recorded and reproduced. 1...NTSC color video signal input terminal, 4...
Decoder, 5... Burst removal circuit, 6... 1/5 time axis compression circuit, 7... Synthesis circuit, 8, 21, 22, 2
6... Switch circuit, 10, 24... Horizontal synchronizing signal separation circuit, 12, 20, 30, 33... 1H delay circuit,
13, 34...Mixing circuit, 16...Reproduction signal input terminal, 18...Addition circuit, 19...Subtraction circuit, 25...Switching pulse generation circuit, 28...5/1 time axis expansion circuit, 29...Encoder, 35...Reproduction color Video signal output terminal.

Claims (1)

[Scope of Claims] 1. A signal portion of at least an effective horizontal scanning period of the second color difference signal of the second color difference signal whose band is equal to or less than the band of the first color difference signal, and a burst. a time-base compression circuit that time-base compresses the signal portion of the level transmission period into a period within the horizontal blanking period of the luminance signal; A time division multiplexed signal generation circuit that obtains a time division multiplexed signal that is time division multiplexed within an interval corresponding to a blanking period and whose phase is inverted every horizontal scanning period, and a time division multiplexed signal that performs time axis compression on the time division multiplexed signal. a first mixing circuit for multiplexing the luminance signals that are not mixed, and means for recording the output multiplexed signal of the first mixing circuit on a recording medium;
a reproducing means for reproducing the multiplexed signal recorded on the recording medium; a comb filter for separately separating and outputting the time division multiplexed signal and the luminance signal from the reproduced multiplexed signal; The first color difference from which the phase inversion for each horizontal scanning period has been removed is based on a switching signal generated from the horizontal synchronization signal in the reproduced luminance signal from the comb-shaped filter to reproduce the reproduced time division multiplexed signal from the filter. switch circuit means for separating and outputting the reproduction signal of the signal and the time-axis compressed second color difference signal; and time-axis expansion of the time-axis compressed second color difference signal from the switch circuit means. a time axis expansion circuit for obtaining a reproduction signal of the second color difference signal returned to the original time axis; It is characterized by comprising a circuit that generates a carrier color signal, and a second mixing circuit that multiplexes the carrier color signal and the reproduced luminance signal from the comb filter, respectively, and outputs the multiplexed signal as a reproduced color video signal. A recording and reproducing device for color video signals. 2. The color image according to claim 1, wherein the comb filter is inactive during the vertical blanking period of the reproduced luminance signal and outputs the reproduced multiplexed signal as it is as the reproduced luminance signal. Signal recording and reproducing device. 3. The switching circuit means generates the switching signal with a polarity determined by the signal obtained by detecting the DC level or burst level of the color reference of the reproduced signal of the second color difference signal from the time axis expansion circuit. 3. The color video signal recording and reproducing apparatus according to claim 1, wherein switching is performed to remove phase inversion for each horizontal scanning period of the time-division multiplexed signal based on . 4. The first color difference signal is an I signal, the second color difference signal is a Q signal, and the time axis compression circuit compresses the effective horizontal scanning period of the Q signal to 1/5. A color video signal recording and reproducing apparatus according to any one of claims 1 to 3, characterized in that: 5. The first color difference signal is an I signal, the second color difference signal is a Q signal, and the time division multiplexed signal generation circuit generates an interval corresponding to a horizontal blanking period of the first color difference signal. 4. A recording and reproducing apparatus for a color video signal according to claim 1, further comprising a circuit for time-division multiplexing the time-axis compressed color difference signal at a constant level.