JPH0314394B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a recording and reproducing device for time-division multiplexed color video signals, and in particular, the present invention relates to a recording and reproducing device for time-division multiplexed color video signals, and in particular, after converting a carrier color signal in an NTSC color television signal into a line-sequential color difference signal or a line-sequential primary color signal, The present invention relates to a recording and reproducing apparatus that records a time-division multiplexed color video signal obtained by axially compressing and time-division multiplexing the time-axis compressed line-sequential signal onto a luminance signal on a recording medium, and reproduces the same. Prior Art Current color video signal recording and reproducing devices (especially
Recording and reproducing devices, which are the mainstream among VTRs, separate luminance signals and carrier color signals from standard format (NTSC, PAL, or SECAM format) color television signals. The carrier color signal is frequency-converted to a low frequency band to become a low-frequency converted carrier color signal, and then frequency-division multiplexed to the frequency-modulated wave, and this frequency-division multiplexed signal is transferred to a recording medium (for example, a magnetic tape). This is a recording/playback device using the so-called low-pass conversion recording/playback method, which performs signal processing on the playback frequency division multiplexed signal in the opposite direction to that during recording to obtain a playback color television signal that complies with the standard system. It is well known that there is. In addition to the low frequency conversion recording and reproducing method, recording and reproducing devices using various recording and reproducing methods have been proposed. This time-division multiplexed signal is frequency-modulated and recorded on a recording medium, and during playback, the reproduced time-division multiplexed signal is processed in the opposite manner to that during recording to create a color television signal that complies with the standard system. A recording/reproducing apparatus configured to obtain a reproduction output has been proposed (see, for example, Japanese Patent Laid-Open No. 5926/1983). 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. The two color difference signals are time-division multiplexed as line-sequential signals that are transmitted alternately every 1H, and this signal is sent to the FM modulator. The output signal of this FM modulator is recorded on a magnetic tape, etc., and during playback, signal processing is performed in the opposite direction to that during recording to obtain a playback color video signal. (hereinafter referred to as the "Plex system"). According to the above-mentioned timeplex method, for example, as shown in FIG. When recording and reproducing a compliant color bar signal, the signal is converted into a time-division multiplexed signal as shown in FIG. Here, in Figure 7B,
Yc indicates a 1H time-axis compressed luminance signal compressed to 41.6μs, which is 80% of the video period of 52μs, and (RY)c and (B-Y)c represent the video period of 52μs.
The color difference signals (R-Y) and (B-Y) of FIG. Furthermore, the separately generated horizontal synchronizing signals H ₁ , H ₂ and color reference levels L ₁ , L ₂ are chronologically generated within the remaining 12 μs (=64−(41.6+10.4)) blanking period of 1H. transmitted. According to the timeplex method for transmitting such time-division multiplexed signals, there is no period during which the luminance signal and the color difference signal are transmitted simultaneously, so the luminance signal and the carrier chrominance signal cannot be combined, as in the case of NTSC or PAL color video signals. 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.
In the case of any of the NTSC, PAL, and SECAM color video signals, even if they are recorded and played back on tracks that are not aligned in H by an azimuth recording/playback system, the time-division multiplexed signal will not be sent to adjacent tracks. is recorded in the form of a frequency-modulated wave signal obtained by frequency modulating a high-frequency carrier wave that has a large azimuth loss effect, so there is almost no crosstalk caused by the azimuth loss effect, and high quality is recorded. You can obtain playback quality of . 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 this, it is possible to obtain a large modulation index and significantly improve the S/N ratio, and furthermore, when the time axis is expanded, it is possible to almost completely eliminate reproduction time axis fluctuations. Problems to be Solved by the Invention However, when the conventional timeplex type recording and reproducing apparatus is applied to an NTSC color television signal, color stripes due to cross colors become noticeable, making it impractical. There was a problem. In other words, to explain this in detail, when recording and reproducing an NTSC color television signal, a conventional timeplex type recording and reproducing device first inputs the signal using a decoder.
After separating the luminance signal and carrier color signal from the NTSC color television signal, and further demodulating the carrier color signal to obtain two types of color difference signals (for example, R-Y and B-Y, or I and Q), This is converted into a line-sequential color difference signal. The luminance signal and the line-sequential color difference signal extracted from the decoder are each time-base compressed separately and then time-division multiplexed as described above. Here, the relationship between the lines (scanning lines) and their positions on the screen, the waveforms of each of the first and last periods of the reference subcarrier of that line, and the color difference signal to be transmitted on that line is illustrated. , as shown in FIG. As is well known, the color subcarrier (reference subcarrier) in the NTSC system is selected to have a frequency 455 times 1/2 of the horizontal scanning wave _fH , so as shown in Figure 8, The reference subcarriers on the lines are in opposite phase. On the other hand, since the two types of color difference signals R-Y and B-Y are transmitted alternately every 1H, the phases of the reference subcarriers for the same color difference signal are in phase in the same frame. Therefore, in a decoder or in a signal processing process such as a transmission line leading to a time-base compression circuit for two types of color difference signals or primary color signals extracted from a television camera, the difference between the luminance signal and the carrier color signal is Interference is inevitable. Therefore, when a carrier color signal transmitted through such a transmission path is demodulated, color noise occurs on the reproduced screen as shown in FIGS. 9A and 9B. Figure 9A shows the dot pattern on the screen for one field, and the dot pattern for the first and third fields is
In the white parts of odd-numbered lines, the color difference signal R-Y is at a high level, and in the black parts, R-Y is at a small level.On the other hand, in the white parts of even-numbered lines, such as the second and fourth lines, the color difference signal R-Y is at a high level. The color difference signal B-Y is at a high level, and in the black portion, B-Y is at a small level. As shown in FIG. 9B, the output waveform of the color demodulation circuit is such that the color difference signal RY changes as shown by the solid line in the first and third frames, and the color difference signal RY changes as shown by the broken line in the second and fourth frames. The signal B-Y is changed. In this way, the color noise appearing on the playback screen is fixed. For example, the luminance signal that interferes with the carrier color signal is the luminance signal of a striped image in which black vertical lines 1 and white vertical lines 2 are alternately arranged in the horizontal direction, as shown in FIG. 10A. Then, the above color noise is the 10th color noise in one frame on the playback screen.
As schematically shown in Figure B, corresponding to the edge portion of vertical lines 1 and 2, a colored portion 3 of the first hue, indicated by hatching downward to the left, occurs on the odd-numbered line,
In the even-numbered lines, a colored portion 4 of the second hue occurs, which is indicated by vertical hatching. Then, in the next frame, a colored portion 3 and a colored portion 4 are generated, respectively, as schematically shown in FIG. 10C. Note that the numbers shown at the right end of FIGS. 10B and 10C indicate line numbers, and R-Y and B-Y indicate color difference signals transmitted on the lines. Note that the hue of each of the colored portions 3 and 4 is determined by the phase difference between the high frequency component of the interfering luminance signal and the reference subcarrier, and the hue is not necessarily the same even on the same line. . As can be seen from FIGS. 9A and 9B and FIGS. 10B and C, color noise has the same fixed pattern in two line sets in the same frame, so it is noticeable and is not practical. Therefore, the present invention solves the above problems by alternately inverting and outputting the phase of a line-sequential signal every multiple horizontal scanning periods in which flickering is not noticeable, thereby recording a time-division multiplexed color video signal. The purpose is to provide a playback device. Means and Effects for Solving the Problems The present invention provides a circuit that alternately inverts and outputs the phase of a line sequential signal every plural horizontal scanning periods in which flicker is not noticeable, and A circuit for differentiating the phase of the leading edge or the trailing edge of the color discrimination signal is provided in each recording system, and the phase of the leading edge or the trailing edge of the color discrimination signal in the reproduced time-division multiplexed color video signal is changed. A detector detects the two types of reproduced line sequential signals obtained by time axis expanding the time axis compressed line sequential signal in the reproduced time division multiplexed color video signal to the original time axis. On the output side of the circuit unit that simultaneously outputs the color difference signals or the primary color signals, the respective phases of the two types of output signals that are synchronized and taken out are transmitted to the plurality of horizontal lines based on the output signals of the detector. An inversion switching circuit is provided for alternately inverting and outputting an output every scanning period, and each embodiment thereof will be described below with reference to FIGS. 1 to 6. Embodiment FIG. 1 shows a block system diagram of an embodiment of the apparatus of the present invention. The apparatus of the present invention is characterized by the transmission form of two types of color difference signals or primary color signals during recording. In FIG. 1, first, the operation during recording will be explained. During recording, the NTSC color television signal to be recorded, which has entered the input terminal 10, is supplied to the decoder 11, while the terminal R
It is supplied to a low-pass filter 13 through a switch circuit 12 connected to the side. Low pass filter 13
For example, the luminance signal as shown in FIG. 2A in the input NTSC color television signal is separated and supplied to the AD converter 14, while the synchronization signal separation circuit 15 separates the horizontal synchronization signal from which equivalent pulses have been removed. is taken out and supplied to the control pulse generator 16 and flip-flop 17. The control pulse generator 16 generates switching pulses that connect the switch circuit 12 and switch circuits 23 and 33 (described later) to the terminal R side during recording based on the output of a mode changeover switch (not shown), and also generates a synchronization signal. Based on the output horizontal synchronization signal of the separation circuit 15 and the output signal of the changeover switch, clock pulses are generated and outputted to the AD converters 14, 24 and DA converters 32, 51, 52, respectively, and are also output to the switch circuits 26, 31. It generates and outputs a switching pulse, and further includes a memory circuit 25,
Writing or reading clock pulses, write/read signals, etc. are generated and outputted to 27, 28, and 29, respectively. Flip-flop 17 is synchronized signal separation circuit 15
The frequency of the horizontal synchronizing signal as shown in FIG. Supply and further divide the frequency by 1/2. As a result, the counter 18
As shown in Figure 3C, a symmetrical square waveform with a 4H period that is phase synchronized with the horizontal synchronization signal is extracted from
This symmetrical square wave is applied to the switch circuit 19 as a switching pulse. The switch circuit 19 selectively outputs the input signals of terminals 19a and 19b during the 2H period when the symmetrical square wave is at high level, and outputs the input signals from terminals 19c and 19d during the 2H period when the symmetrical square wave is at low level.
Switching control is performed to select and output the input signals of. In addition, the switch circuit 22 is connected to the terminal 22 during the 1H period when the pulse shown in FIG. 3B is at a high level.
Select and output the input signal of a, and it is low level.
During the 1H period, switching control is performed to selectively output the input signal of the terminal 22b. On the other hand, the decoder 11 has a configuration in which the carrier color signal in the input NTSC color television signal is separated using, for example, a comb filter, and then a color demodulation circuit obtains two types of color difference signals B-Y and R-Y. has been done. The two types of color difference signals B-Y and R-Y outputted in parallel from the decoder 11 are supplied in parallel to the terminals 19a and 19b of the switch circuit 19, respectively, while passing through inverters 20 and 21 to the terminal 19c of the switch circuit 19. , 19d in parallel. As described above, the switch circuit 19 is configured to be switched and connected every 2H using the symmetrical square wave shown in FIG.
Y is supplied to the terminal 22a of the switch circuit 22, and the color difference signal R-Y is supplied from the common terminal 19f to the terminal 22b of the switch circuit 22. During the next 2H period, the phase of the color difference signal B-Y is inverted from the common terminal 19e. Selectively outputting the signal -(B-Y) to the terminal 22a and selectively outputting the phase inverted signal -(RY) of the color difference signal R-Y from the common terminal 19f to the terminal 22b are repeated alternately every 2H. . Further, the switch circuit 22 is connected to the third switch circuit 22 as described above.
Since the pulse shown in Figure B (a symmetrical square wave with a period of 2H) is switched and connected every 1H, the output signal of the switch circuit 22 is as schematically shown in Figure 3D.
2H is a line-sequential color difference signal in which two types of color difference signals B-Y and R-Y are synthesized alternately in time series every 1H.
A line-sequential color difference signal whose phase is inverted each time is obtained. Therefore, the terminal 19b of the switch circuit 19
When the color difference signal R-Y input to the terminal 19a has a waveform as shown in FIG. 2B, and the color difference signal B-Y input to the terminal 19a has a waveform as shown in FIG. The signal becomes a line-sequential color difference signal as shown in FIG. The line-sequential color difference signal shown in FIG.
Analog-to-digital conversion is performed based on a 4 MHz clock pulse, and a digital line sequential color difference signal sampled at a sampling frequency of 4 MHz is generated and outputted and supplied to the memory circuit 25. Memory circuit 25
Like the memory circuits 27, 28, and 29 described later, it is composed of a random access memory (RAM) and an address counter, and based on the read/write signal and clock pulse from the control pulse generator 16, the 1H After writing a digital color difference signal for a video period within a video period based on a write clock pulse of, for example, 4 MHz, the written digital color difference signal is written based on a read clock pulse of, for example, 20 MHz from the device 16, and is then synchronized with the horizontal synchronization described later. Read out within the horizontal blanking period excluding both signal and achromatic level transmission periods. Therefore, the memory circuit 25 intermittently outputs digital line sequential color difference signals whose time axis has been compressed to 1/5.
It is read out in 1H cycles and supplied to the switch circuit 31. Note that the output time axis compressed digital line sequential color difference signal of the memory circuit 25 is also supplied to the switch circuit 26 and the memory circuit 27, respectively, but since the switch circuit 26 is controlled to a signal passage blocking state during recording, the memory circuit 27 does not substantially operate. On the other hand, the luminance signal shown in FIG.
The signals are supplied to memory circuits 28 and 29 after being analog-to-digital converted based on, for example, a 16 MHz clock pulse from a control pulse generator 16. The memory circuits 28 and 29 are connected to the leads from the device 16, respectively.
By the write signal, during the 1H period in which one side is performing a write operation, the other side is controlled to read out the digital luminance signal written immediately before the 1H period. Here, the write clock pulses of the memory circuits 28 and 29 are selected to be, for example, 16 MHz, and the read clock pulses are selected to be, for example, 20 MHz.
Therefore, from the memory circuits 28 and 29, digital signals in which the luminance information of the 1H period is time-axis compressed to 4/5 are taken out alternately every 1H period without any loss of information, and are supplied to the switch circuit 31. be done. The switch circuit 31 also receives an achromatic level signal (here, digital data) taken out from the achromatic level detector 30.
is supplied. This achromatic level signal is a DC level of the color reference of the color difference signals R-Y and B-Y, and is a signal of a level corresponding to the median value of the maximum amplitude of the color difference signals R-Y and B-Y ( (The color difference is zero, that is, the level is colorless). The switch circuit 31 switches the memory circuits 28 and 29 based on the switching signal from the device 16.
After selectively outputting the 4/5 time-axis compressed digital luminance signal extracted from the memory circuit 28 or 29 which is performing the read operation,
Subsequently, the achromatic level signal is selectively output for a predetermined period of time, and from the end of the predetermined period, the - digital color difference signal read out from the memory circuit 25 and time-axis compressed to 1/5 is selectively output. repeat. In this way, the digital signals synthesized and extracted in time series from the switch circuit 31 are
DA converter 32 where said device 16
The signal is digital-to-analog converted by a 20 MHz clock pulse to form a time-division multiplexed color video signal having a waveform as shown in FIG. 2F. In FIG. 2F, h ₁ to _{h 4} are time-base compressed horizontal synchronization signals, a ₁ to a ₄ are achromatic level signals,
Yc is a time axis compressed luminance signal, (RY)c, (B-
Y)c are time-axis compressed color difference signals obtained by time-axis compressing the color difference signals R-Y and B-Y, respectively, and -(R-
Y)c and -(B-Y)c are color difference signals -(R-Y),
-(B-Y) are respectively time-axis compressed and are obtained by compressing the time axis. As shown in FIG. 2E, the digital data of the achromatic level signal gate output from the switch circuit 31 has a pulse peak value at the achromatic level and a time axis compressed color difference signal ( The pulse width immediately before the time axis compressed color difference signal (B-Y) c is T ₁ , the pulse width immediately before the time axis compressed color difference signal (B-Y) c is T ₂ , the time axis compressed color difference signal -(R-
The pulse width immediately before Y)c is _T3 , and the pulse width immediately before the time-axis compressed color difference signal -(B-Y)c is _T4.
This shows the pulse information. Therefore, depending on whether the pulse width is one of T ₁ to _{T 4} , the color difference signals (RY)c, (B-Y)c, -(RY)
c, -(B-Y)c transmission lines can be identified, and the achromatic level signal is also transmitted as a color discrimination signal. Here, the above period T ₁ to T ₄
The period of the sum of the transmission period of the time axis compressed luminance signal and the immediately preceding transmission period is selected to be equal to each other. For example, if t is a period of 1/1280 times 1H, the period T 1 is 68t, and the period T ₁ is 68t. T ₂ was selected to be 48t. Furthermore, the transmission period of the time-domain compressed color difference signal within 1H is (R-Y)c, (B-Y)c, -(R-
Both Y)c and -(B-Y)c are constant, and are selected to be, for example, a period 13/80 times 1H. Further, the rising (leading edge) position of the achromatic level signal with respect to the reproduced horizontal synchronization signal shown in FIG. 2E differs depending on the type of color difference signal. -(R-
The first rising position of the achromatic level signal transmitted immediately before Y)c is higher than the first rising position of the achromatic level signal transmitted immediately before the time axis compressed color difference signal (B-Y)c, -(B-Y)c. The phase is advanced compared to the second rising position of the match level signal. Furthermore, the falling (trailing edge) position of the achromatic level signal with respect to the reproduced horizontal synchronization signal is made different depending on the polarity of the color difference signal.
The first falling position of the achromatic level signal immediately before Y)c, -(B-Y)c is immediately before the time axis compressed color difference signal (R-Y)c, (B-Y)c. The phase is advanced compared to the second falling position of the achromatic level signal. As a result, the pulse width T ₁ to _{T 4} of the above achromatic level signal is
For example, the relationship is T ₁ > T ₃ > T ₂ > T ₄ . The time-division multiplexed color video signal shown in FIG. 2F is supplied to the pre-emphasis circuit 34 through the switch circuit 33 in FIG. The recording head 4 is processed through a known recording signal processing circuit in a VTR consisting of a high-pass filter 37, a high-pass filter 38, and a recording amplifier 39.
0, thereby recording on the magnetic tape 41a. Next, the operation during reproduction will be explained. At this time, the switch circuits 12, 23 and 33 are respectively connected to the terminal P side. The reproduction head 42 reproduces the time division multiplexed signal recorded on the magnetic tape 41b in the form of a frequency modulated wave, and this reproduced frequency modulated wave is transmitted to the reproduction amplifier 43, the equalizer circuit 44, the high-pass filter 45, and the FM. The signal is passed through a known reproduced signal processing circuit comprising a demodulator 46 and a de-emphasis circuit 47 into a reproduced time-division multiplexed color video signal as shown in FIG. 2F. This reproduced time-division multiplexed color video signal passes through a switch circuit 12 and a low-pass filter 13 connected to a terminal P, and then passes through an AD converter 14, a synchronization signal separation circuit 15, an achromatic level detector 48, and an inverting/non-inverting signal. are supplied to the inversion detector 49 respectively, while the switch circuit 2
3 to the AD converter 24. The horizontal and vertical synchronization signals separated by the synchronization signal separation circuit 15 are supplied to a control pulse generator 16. The AD converter 14 performs analog-to-digital conversion of the reproduced time-division multiplexed color video signal based on a clock pulse of, for example, 20 MHz from the control pulse generator 16, and supplies digital signals to memory circuits 28 and 29, respectively. The memory circuits 28 and 29 are connected to the control pulse generator 16.
One of them is controlled to perform a write operation only during a period when a time-axis compressed luminance signal is transmitted based on a read/write signal from the other, and the other is controlled to perform a read operation for a predetermined period.
Repeated alternately every 1H. Furthermore, the writing clock pulses of the memory circuits 28 and 29 are, for example, 20 MHz, and the reading clock pulses are 16 MHz.
Hz. Therefore, from the memory circuits 28 and 29, reproduced digital luminance signals whose time axes have been expanded by 5/4 and whose time axes have been returned to the original state are taken out alternately every 1H and are supplied to the switch circuit 31. On the other hand, the digital signal taken out from the AD converter 24 is supplied to a memory circuit 25 which is controlled to perform a writing operation only during the transmission period of the digital time-base compressed color difference signal. It is written based on a 20 MHz write clock pulse and then read based on a 4 MHz read clock pulse. Therefore, the digital line sequential color difference signal whose time axis has been expanded by 5/1 and returned to the original time axis is taken out from the memory circuit 25 and is supplied to the switch circuit 26 and the memory circuit 27, respectively. After writing the output signal of the memory circuit 25 based on the 4MHz clock pulse from the control pulse generator 16, the memory circuit 27 outputs 4M
Read out the written signal based on the Hz clock pulse. As a result, from the memory circuit 27
The reproduced digital color difference signal delayed by 1H is extracted in time series and supplied to the switch circuit 26. Therefore, the reproduced digital color difference signal R-Y or -(R-Y) is output from one of the memory circuits 25 and 27.
In the video period within 1H in which the B-Y or -(B-
Y) will be taken out. Further, the achromatic level detector 48 latches the average value of several sample points of the achromatic level signal multiplexed at a position after a certain period of time from the horizontal synchronizing signal position using a latch circuit, and also It is determined whether the rising position of the level signal is the above-described first rising position or the second rising position, and a switching signal is generated based on the result of the judgment and is supplied to the switch circuit 26. During the horizontal blanking period, the switch circuit 26 passes the achromatic level data latched by the latch circuit in the achromatic level detector 48 as it is and supplies it to the inverting/non-inverting detector 49;
In the subsequent video period, the color difference signal (R-Y) or -(R-
When the digital color difference signal of Y) is output, it is selectively outputted to the first input terminal of the inversion switching circuit 50, and the digital color difference signal output from the memory circuit 27 at that time is output to the second input terminal of the inversion switching circuit 50. Selected output is made to the input terminal of memory circuit 2.
When a digital color difference signal (B-Y) or -(B-Y) is output from 5, it is selectively outputted to the second input terminal of the inversion switching circuit 50, and the memory circuit 27 at that time is output. The output digital color difference signal is selectively outputted to the first input terminal of the inversion switching circuit 50. As a result, the first input terminal of the inversion switching circuit 50 receives the color difference signal R-Y or -.
(RY) digital color difference signal is always supplied,
And the second input terminal receives the color difference signal B-Y or -
(B-Y) digital color difference signals are always supplied. On the other hand, the inversion/non-inversion detector 49 detects whether the fall position of the achromatic level signal is the first fall position or the second fall position, and detects whether the fall position of the achromatic level signal is the first fall position or the second fall position. When this is detected, the inversion switching circuit 50 is controlled to perform the inversion operation until the next detection point, and when the second falling position is detected, the inversion switching circuit 50 is controlled to perform the inversion operation until the next detection point. control so that the reversing operation is stopped until the next detection point. As a result, the color difference signal -(R-
When the digital color difference signals of Y) and -(B-Y) are received, an inversion operation is performed and the color difference signal R-
The digital color difference signals of Y and B-Y are sent to the DA converter 5.
1 and 52 in parallel, and the other color difference signal R-
When Y and BY digital color difference signals are input, the input digital color difference signals are outputted in parallel to the DA converters 51 and 52 as they are without performing an inversion operation. During the horizontal blanking period, achromatic level data from the achromatic level detector 48 is supplied to the DA converters 51 and 52 through the switch circuit 26 and the inversion switching circuit 50, respectively. In this way, the digital color difference signal (R-Y) is always supplied to the DA converter 51, and the digital color difference signal (B-Y) is always supplied to the DA converter 52.
-Y) digital color difference signals are supplied. D.A.
The converters 51 and 52 perform digital-to-analog conversion of the input digital color difference signals using a 4MHz clock pulse from the control pulse generator 16, respectively, to generate reproduced color difference signals (R-Y) and (B-Y). This is output to the encoder 53. These reproduced color difference signals (R-Y) and (B-
Y) are color difference signals obtained by synchronizing line-sequential color difference signals, and both color difference signals are transmitted together in each 1H period. On the other hand, during reproduction, the switch circuit 31 alternately selects and outputs only the reproduced digital luminance signals output from the memory circuits 28 and 29 and supplies them to the DA converter 32. The DA converter 32 performs digital-to-analog conversion of the input digital luminance signal using a 16 MHz clock pulse from the control pulse generator 16, and outputs a reproduced luminance signal as shown in FIG. 2A. This reproduced brightness signal is transmitted to the switch circuit 33.
The signal is supplied to the encoder 53 through. The encoder 53 outputs a reproduced luminance signal and a reproduced color difference signal (R-
From Y) and (B-Y), a reproduced color video signal conforming to the NTSC system is generated and output to the output terminal 54. Next, it will be explained how the color noise that conventionally occurs in the reproduced image becomes less noticeable in the above embodiment. In this embodiment, the line sequential signals supplied to the AD converter 24 include two types of color difference signals R-Y and B-Y, respectively, as schematically shown in FIG. 3D.
It is a signal obtained by inverting the phase of a line-sequential color difference signal that is synthesized alternately in time series every 1H, and therefore, every 2H.
Decoder 1 corresponds to the position of the line on the screen.
The relationship between the first and last one-cycle waveforms of each line of the reference subcarrier of the color demodulation circuit in 1 and the color difference signal to be transmitted on that line is illustrated as follows.
The result will be as shown in FIG. As can be seen from Figure 4, the color difference signals transmitted on two adjacent lines in one frame are of the same type and have opposite polarities (for example, -(B-Y) on the 264th line and -(B-Y) on the 2nd line). B-Y, -(R-Y) of the 265th line
and -(RY) on the third line), and the reference subcarriers for the same type of color difference signals having mutually different polarities are in phase. Also, in the next frame, color difference signals are transmitted in a different order from the previous frame (for example, in the 526th line one frame after the first line, B-Y, and one frame after the 264th line) R-Y on the 789th line, -(RY) on the 527th line, B-Y on the 790th line...). As a result, the NTSC signal supplied to the decoder 11
The luminance signal in the system color television signal has black vertical lines 56 and white vertical lines 57 arranged alternately in the horizontal direction as shown in FIG. 5A, similar to that shown in FIG. 10A. Assuming that the brightness signal is the brightness signal of the image of the striped pattern, there will be a certain amount of light on the playback screen at the positions corresponding to the vertical lines 56 and 57 due to interference between the brightness signal and the carrier color signal during the signal processing process. In one frame, colored portions appear as schematically shown in FIG. 5B, and in the next frame, as schematically shown in FIG. 5C. Here, colored portions 58 such as the 264th and 268th lines indicated by horizontal hatching in FIGS. 5B and 5C correspond to the first phase of the reference subcarrier that can demodulate the color difference signal -(B-Y). The colored portions 59, such as the second, 266th, and sixth lines, which are determined by the phase of the high frequency component of the luminance signal and indicated by hatching on the lower right, are the second, second, and sixth lines of the reference subcarrier that can demodulate the color difference signal B-Y. It is determined by the phase of the high frequency component of the luminance signal with respect to the phase of . The above first and second phases are at the same level as shown in Figure 4, but the polarities of the color difference signals B-Y differ by 180 degrees, and the luminance signals are correlated in the vertical direction as shown in Figure 5A. Because of this, the colored portions 58 and 59 in the vertical direction have first and second complementary hues that differ by 180 degrees from each other on a vector scope. Similarly, colored portions 60 such as the 265th, 5th, and 789th lines indicated by hatching in the downward left direction and colored portions 61 such as the 3rd, 267th, and 527th lines indicated by vertical hatching are respectively Color difference signal RY, -
It is determined by the phase of the high frequency component of the luminance signal with respect to the third and fourth phases of the reference subcarrier that can demodulate (RY), but the third and fourth phases are in phase. Since the polarities of the color difference signals RY are opposite to each other and the luminance signals are correlated in the vertical direction as shown in FIG. 5A, the colored portions 60 and 61
have hues that differ by 180 degrees on the vectorscope in the vertical direction, and the third phase of the reference subcarrier differs by 90 degrees from the first phase, so the hues of the colored portions 60 and 61 are the same in the vertical direction. The colored portions 58 and 59 have different hues. However, in all of the colored parts 58 to 61, the phases of the high frequency components of the luminance signal with respect to the reference subcarrier are usually not the same on the same line, so even the colored parts with the same code usually exhibit different hues. . In addition, the numbers shown on the right side in FIGS. 5B and C indicate line numbers, and R-Y, B-Y, -(R
-Y) and -(B-Y) indicate color difference signals transmitted on that line. As can be seen from FIGS. 5B and 5C, the colored parts 58 to 61 of each frame are formed by two adjacent lines (for example, the 264th line and the 2nd line, the 265th line and the 3rd line, the 266th line and the 266th line). The 4th line, the 789th line and the 527th line, the 790th line and the 528th line, etc.) will have opposite hues, and the same line for each frame (for example, the 1st line and the 526th line, etc.) will have different hues. , because the colored parts appear without being fixed, the colored stripes are hardly noticeable on the playback screen. Next, if this embodiment is further developed, it will be understood that it is sufficient to invert the phase of the line-sequential color difference signal every even numbered lines. This is because if the line-sequential color difference signals are inverted every odd numbered lines, the numbers of color difference signals with positive polarity and color difference signals with negative polarity will not match, and the entire screen will be slightly colored. Therefore, if the line-sequential color difference signals are inverted every four lines, the transmission lines and the types and polarities of the transmitted color difference signals will be as shown in the following table.

[Table] Furthermore, when the phase of the line-sequential color difference signal is inverted every 6 lines, the transmission lines and the types and polarities of the transmitted color difference signals are as shown in Table 2 below.

[Table] As can be seen from Tables 1 and 2, in each of the above cases, no line becomes a fixed color difference signal, so color noise can be visually reduced in practice. In addition, when phase-inverting the line-sequential color difference signal at a long period such as 4 lines or 6 lines, it is sufficient to select the frequency division ratio of the counter 18 to a phase inversion period such as 1/4 or 1/6. The output of the counter 18 is as shown in FIG. 6C, and the output signal of the switch circuit 22 is as schematically shown in FIG. 6D. Here, each signal shown in FIGS. 6A and 6B is the same signal as that shown in FIGS. 3A and 3B. Taking the above idea further, if the phase inversion period of the line-sequential color difference signal is long, even if the number of signals with positive polarity and negative polarity of the color difference signal does not match, the difference will be small. Therefore, it is also possible to invert every odd numbered line. However, in the present invention,
If the phase inversion period of the line-sequential color difference signal is too long, flicker becomes noticeable, so the phase inversion period is selected so that the flicker is not noticeable (for example, several tens of lines or less). Application Example Note that the present invention is not limited to the above embodiments; for example, a luminance signal may be time-division multiplexed into a time-domain compressed line-sequential signal by removing a portion of the luminance signal without time-domain compression. Further, the two types of color difference signals may be a combination of one of B-Y and R-Y and a G-Y signal, or a combination of an I signal and a Q signal, or three primary color signals R, G, and B. A combination of two of these primary color signals may also be used. Further, as the color discrimination signal, it is also possible to use, for example, a burst signal that is multiplexed with the horizontal synchronizing signal of one transmission line depending on the type of the color difference signal and whose frequency varies depending on the polarity. Alternatively, the line-sequential color difference signal may be generated directly from two baseband color difference signals or primary color signals obtained from a television camera, for example, before being converted into a carrier color signal. Furthermore, when the phase inversion period of the line-sequential color difference signal is 2H, a flip-flop can be used instead of the counter 18. Effects of the Invention As described above, according to the present invention, the phase of a line-sequential signal obtained by chronologically synthesizing two types of color difference signals or primary color signals alternately every 1H is calculated every multiple horizontal scanning periods in which flicker is not noticeable. The time-division multiplexed color video signal obtained by time-division multiplexing the luminance signal and the color discrimination signal after being inverted and compressed on the time axis, respectively, is recorded and played back. Color noise (colored parts) due to interference with frequency components can be a pattern of different hues for each frame, and does not appear as a fixed pattern. Therefore, due to the integral effect of the human eye, color noise is visually The color noise is averaged and can be made almost indistinguishable, and flicker can be made less noticeable compared to the case where the phase of the color difference signal is inverted line-by-line for each frame or field. , the timeplex method can be suitably applied to NTSC color television signals.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram showing one embodiment of the apparatus of the present invention, and FIGS. 2A to 3F and 3A to D are signal waveforms and color difference signal transmission order for explaining the operation of the block system shown in FIG. 1, respectively. FIG. 4 shows the position of a line on the screen in the device of the present invention, the waveforms of the first and last periods of the reference subcarrier of that line, and
A diagram showing an example of the relationship between the line and the color difference signal to be transmitted, and FIGS. 5A to 5C are diagrams schematically showing the occurrence of color noise, etc. that occurs in a reproduced image in the apparatus of the present invention, and FIGS. 6A to 6C, respectively. D shows signal waveform diagrams for explaining the operation of other embodiments of the apparatus of the present invention, and FIGS. 7A and 7B show examples of standard color television signal waveforms and time-division multiplexed color video signal waveforms according to the timeplex method. 8 is a diagram showing an example of the relationship between the position of a line on the screen in a conventional device, the waveform of each of the first and last cycles of the reference subcarrier on that line, and the color difference signal to be transmitted on that line. , No. 9
Figures A and B are diagrams showing an example of the dot pattern of the reproduced image and the output waveform of the color demodulation circuit by the conventional device, and Figures 10A to C are diagrams schematically showing color noise, etc. that occur in the reproduced image in the conventional device, respectively. It is. 1,56...Black vertical line, 2,57...White vertical line, 10...NTSC color television signal input terminal, 11...Decoder, 14,24...
AD converter, 15... Synchronization signal separation circuit, 16...
...Control pulse generator, 17...Flip-flop, 18...Counter, 19, 22, 2
6, 31... switch circuit, 25, 27, 28,
29... Memory circuit, 30... Achromatic level generator, 32, 51, 52... DA converter,
37... Frequency modulator, 41a, 41b... Magnetic tape, 48... Achromatic level detector,
49...Inversion/non-inversion detector, 50...Inversion switching circuit, 53...Encoder, 54...Reproduction NTSC
Color video signal output terminal.

Claims (1)

[Claims] 1 Two types of color difference signals or primary color signals obtained separately from the carrier color signal in the color television signal to be recorded or directly generated from a television camera etc. are converted into line sequential signals, and the corresponding A time-axis compressed line-sequential signal obtained by time-axis compressing a line-sequential signal,
A time-base compressed luminance signal obtained by time-base compressing the luminance signal or a non-time-base compressed luminance signal obtained by removing a portion thereof and a separately generated color discrimination signal are obtained by time-division multiplexing within each horizontal scanning period. A time-division multiplexed color video signal is recorded on a recording medium, and during reproduction, the time-division multiplexed color video signal reproduced from the recording medium is subjected to signal processing opposite to that during recording, and reproduced in accordance with the standard method. In a recording and reproducing apparatus for obtaining a color video signal, the color television signal to be recorded is an NTSC color television signal,
Two types of color difference signals or primary color signals obtained by demodulating the carrier color signal in the NTSC color television signal or directly generated from a television camera etc. are alternately scanned every horizontal scanning period. A circuit that alternately inverts and outputs the phase of sequential signals synthesized serially for each of a plurality of horizontal scanning periods in which flicker is not noticeable; or a circuit for differentiating the phase of the trailing edge in the recording system, and a detector for detecting the phase of the leading edge and the trailing edge of the color discrimination signal in the reproduced time division multiplexed color video signal; The two types of color difference signals or primary color signals are simultaneously obtained from the reproduced line sequential signal obtained by time-axis expanding the time-axis compressed line-sequential signal in the time-division multiplexed color video signal to the original time axis. The phase of each of the two types of output signals that are synchronized and taken out is alternately inverted for each of the plurality of horizontal scanning periods based on the output signal of the detector. What is claimed is: 1. A recording and reproducing device for time-division multiplexed color video signals, characterized in that an inversion switching circuit is provided for outputting a time-division multiplexed color video signal.