JPH03207193A - Video tape recorder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a video tape recorder that can convert a television signal recorded on a magnetic tape into a television signal of a system different from the recording television signal system and reproduce it. It is related to.

Conventional Technology Most of the video tape recorders (hereinafter referred to as VTRs) in general use today are compatible only with the television format of the country in which they are used, and these VTRs cannot record video tapes recorded with VTRs of different formats. It could not be played. In some areas, VTRs are shipped that are compatible with multiple television formats, and although these VTRs can play video tapes recorded in different formats, they cannot be played back in the format recorded on the magnetic tape. Therefore, it was necessary to use a monitor TV compatible with that system. In order to play back signals recorded in a different format from a monitor TV using a specific television format, it is necessary to convert the television format. VTRs capable of converting television formats have been proposed in recent years.

An example of a conventional VTR capable of converting television formats will be described below with reference to the drawings.

Figure 4 shows a conventional VTR that can convert television formats.
FIG. 2 is a block diagram showing the configuration of the main parts of the reproduction system. In FIG. 4, a Takagi pass filter 62 and a luminance signal regeneration processing circuit 63 are connected to the input terminal 61, and a low pass filter 64 and a chrominance signal regeneration processing circuit 65 are connected to the input terminal 61. has been done. This color signal reproduction processing circuit 65 is an automatic color level control circuit (hereinafter referred to as
66 (referred to as an ACC circuit) and a frequency conversion circuit 67 that converts a low frequency carrier color signal outputted from the ACC circuit 66 into a carrier color signal. The YC mixing circuit 68 mixes the reproduced luminance signal and the reproduced carrier color signal, and the YC separation circuit 69 separates the composite video signal output from the YC mixing circuit 68 into a luminance signal and a color signal. 70 is a color signal demodulation circuit that demodulates the carrier color signal into a color difference signal; 71 is a field frequency/scanning line number conversion circuit that converts the field frequency/scanning line number of the luminance signal and color signal; 72 is a color signal demodulator that converts the color difference signal into a carrier color signal; The color signal demodulation circuit 70, the color signal modulation circuit 72, and the field frequency/scanning line number conversion circuit 71 are controlled by a conversion controller 73. The luminance signal output from the field frequency/scanning line number conversion circuit 7l and the carrier color signal output from the color signal modulation circuit 72 are YC.
The mixed signals are mixed in a mixer 74 and outputted from an output terminal 75.

The operation of the conventional VTR configured as described above and capable of converting television formats will be described below.

First, to the input terminal 61, a signal reproduced from a magnetic tape through a head, a reproduction amplifier, etc. is input. This signal is passed through the Takagi pass filter 62, and the F corresponding to the Takagi component is
Only the M-converted luminance signal is passed through and sent to the luminance signal reproduction processing circuit 63. In the luminance signal reproduction processing circuit 63, the FM
The signal is subjected to predetermined processing such as demodulation and de-enhancement by the luminance signal reproduction processing system in the VTR, and then sent to the YC mixer 68. On the other hand, the input signal input from the input terminal 6l is also sent to the low-pass filter 64, where only the low-pass converted carrier color signal corresponding to the low-frequency component is passed through and sent to the color signal reproduction processing circuit 65. In the color signal reproduction processing circuit 65, the ACC circuit 66 suppresses the amplitude fluctuation of the color signal, and the frequency conversion circuit 67 converts the low-frequency converted carrier color signal into the original carrier color signal. is processed and sent to a YC mixer 68. The reproduced luminance signal and the carrier color signal are mixed in the YC mixer 68 and sent to the YC separation circuit 69, where they are again separated into a luminance signal and a carrier color signal. If the system conversion circuit is built into the VTR, the YC mixing circuit 68 and YC separation circuit 69 can be omitted, but if the VTR and system conversion circuit are separated into separate units, then the The structure is as follows. Further, the luminance signal separated by the YC separation circuit 69 is converted into a field frequency and the number of scanning lines by a field frequency/scanning line number conversion circuit 71, and is sent to a YC mixer 74. Further, the carrier color signal is converted into a color difference signal by a color signal demodulation circuit 70, and then converted into a field frequency and the number of scanning lines by a field frequency/scanning line number conversion circuit 71, and then sent to a color signal modulation circuit 72. The color signal modulation circuit 72 converts the color difference signal into a television system carrier color signal outputted from an output terminal 75 and sends it to the YC mixer 74 .

The YC mixer 74 mixes the luminance signal and the carrier color signal,
It is output to the output terminal 75.

In the above explanation, we have explained the process for converting the field frequency, number of scanning lines, and color signal method of a television signal reproduced from a magnetic tape. However, only the color signal method is used without converting the field frequency and number of scanning lines. When converting, in FIG. 4, the conversion process in the field frequency/scanning line number conversion circuit 71 is not performed.

Further, when outputting a signal reproduced from a magnetic tape without format conversion, the signal mixed by the YC mixing circuit 68 may be outputted from the output terminal 75, or the field frequency/scanning signal may be output from the output terminal 75. The conversion process in the line number conversion circuit 71 may not be performed, and the color signal modulation circuit may be configured to re-modulate the television system color signal reproduced from the magnetic tape and output it.

Problems to be Solved by the Invention However, in the above conventional configuration, the low frequency conversion carrier color signal reproduced from the magnetic tape is first converted into a carrier color signal,
Since the carrier color signal is further demodulated into a color difference signal and modulated again, frequency conversion is performed three times (low-pass conversion carrier color signal → carrier color signal → color difference signal → carrier color signal), and the circuit As the scale increases, there is a problem in that signal deterioration occurs due to repeated frequency conversion.

The present invention solves the above-mentioned conventional problems, and aims to provide a VTR that can reduce the circuit scale and convert television signals with less signal deterioration. .

Means for Solving the Problems In order to solve the above problems, the VTR of the present invention is a video recorder in which the luminance signal is FM-converted, the color signal is frequency-converted to the lower frequency side of the FM-converted luminance signal, and then recorded on a magnetic tape. A tape recorder, comprising: a color signal demodulating means for demodulating a low frequency conversion carrier color signal reproduced from a magnetic tape into a color difference signal; a luminance signal reproduction processing means for processing an FM luminance signal reproduced from the magnetic tape; It is connected to a color signal demodulation means and a brightness signal reproduction processing means, and a brightness signal and a color signal are input thereto;
A field frequency/scanning line number conversion means for converting the field frequency and number of scanning lines of a television signal, and a television signal system in which a color difference signal from the field frequency/scanning line number conversion means is recorded on a magnetic tape. A color signal modulation means capable of converting the carrier color signal into a carrier color signal of a different system.

Operation With the above configuration, the low frequency conversion carrier color signal reproduced from the magnetic tape is directly demodulated into a color difference signal by the color signal demodulation means,
The field frequency/scanning line number conversion means converts the field frequency and the number of scanning lines appropriately, and then the output carrier color signal is modulated by the color signal modulation means. It is only necessary to carry out gamut conversion (carrier color signal → color difference signal → carrier color signal), the structure is simple, the circuit scale is reduced, and a VTR that can convert television signals with less signal deterioration has been realized. It will be possible.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a VTR playback processing system in an embodiment of the present invention. In FIG. 1, an input terminal 1 is connected to a Takagi pass filter 2 and a luminance signal regeneration processing circuit 3 is connected to the input terminal 1, and a low pass filter 4 is connected to the input terminal 1, an ACC circuit 5 is connected to the input terminal 1, and an ACC circuit 5 is connected to the input terminal 1. A color signal demodulation circuit 6 is connected to. A color signal demodulation circuit 6 demodulates this low-frequency carrier color signal into a color difference signal, a field frequency/scanning line number conversion circuit 7 that converts the field frequency and number of scanning lines of the luminance signal and color signal, and a color difference signal into a carrier color signal. Each of the color signal modulation circuits 8 to be converted is controlled by a conversion controller 9. The luminance signal output from the field frequency/scanning line number conversion circuit 7 and the carrier color signal output from the color signal modulation circuit 8 are mixed by a YC mixer 10 and output from an output terminal 11.

Regarding the conventional VTR configured as above, the following will be explained.
Let's explain its operation.

First, a signal reproduced from the magnetic tape through a head, a reproducing amplifier, etc. is input to the input terminal 1, and only the FM converted luminance signal corresponding to the Takagi component is passed through the Takagi pass filter 2, and then sent to the luminance signal reproduction processing circuit 3. Sent. The luminance signal reproduction processing circuit 3 performs predetermined processing such as FM modulation, de-emphasis, etc. of the luminance signal reproduction processing system in a VTR, and sends the signal to the field frequency/scanning line number conversion circuit 7. On the other hand, the signal input from the input terminal 1 is also supplied to the low-pass filter 4, and the low-pass converted carrier color signal corresponding to the low-frequency component thereof is passed through.The ACC circuit 5 suppresses the level fluctuation of the color signal, and the color signal is The signal is supplied to the demodulation circuit 6. The color signal demodulation circuit 6 demodulates the low frequency converted carrier color signal into a color difference signal according to the format of the television signal reproduced from the magnetic tape, and this color difference signal is sent to the field frequency/scanning line number conversion circuit 7. It will be done. The field frequency/scanning line number conversion circuit 7 converts the field frequency and scanning line number of the input luminance signal and color difference signal as appropriate, and the luminance signal becomes Y
The color difference signal is supplied to the C mixer 10 and the color signal modulation circuit 8, respectively. The color signal modulation circuit 8 modulates the color difference signal into a television system carrier color signal output from the output terminal l1, and supplies the signal to the YC mixer 10. The YC mixer IO mixes the system-converted luminance signal and color signal and outputs the mixed signal from the output terminal 11.

In the above explanation, we have explained the process for converting the field frequency, number of scanning lines, and color signal method of a television signal reproduced from a magnetic tape. However, only the color signal method is used without converting the field frequency and number of scanning lines. When converting, in FIG. 1, the conversion process in the field frequency/scanning line number conversion circuit 7 is not performed. In addition, when outputting the signal reproduced from the magnetic tape without format conversion, the field frequency/scanning line number conversion circuit 7 does not perform conversion processing, and the color signal modulation circuit outputs the signal reproduced from the magnetic tape. It is only necessary to re-modulate the color signal of the system and output it. The conversion controller 9 controls a color signal demodulation circuit 6, a field frequency/scanning line number conversion circuit 7, and a color signal modulation circuit according to the format of the television signal reproduced from the magnetic tape and the format of the television signal output from the output terminal 11. Controls circuit 8. For example, P.A.
When reproducing an L format tape and outputting it in the NTSC format, the color signal demodulation circuit 6 operates to demodulate the PAL format low frequency conversion carrier color signal into a color difference signal, and performs field frequency/scanning line number conversion. In circuit 7, the field frequency is 30
th, the number of frame scanning lines is 625, and the field frequency is 60H! , and the color signal modulation circuit 8 operates to convert the color difference signal into an NTSC carrier color signal. Also, SECAM
When playing back a tape in the PAL format and outputting it in the PAL format, the color signal demodulation circuit 6 outputs the 1/4 countdown FM color signal of the SECAM format (this signal is also included in the low frequency conversion carrier color signal in the present invention). The signal is demodulated into a color difference signal, and the field frequency/scanning line number conversion circuit 7 outputs the signal without performing any conversion, and the color signal modulation circuit 8 operates to convert the color difference signal into a PAL carrier color signal. In other combinations of conversions, each circuit is controlled in accordance with the input/output television signal format (field frequency, number of scanning lines, color signal format), as described above.

Next, the color signal demodulation circuit 6 will be explained in more detail. FIG. 2 is a block diagram showing an example of the configuration of the color signal demodulation circuit 6 shown in FIG. 1. In FIG. 2, input terminal 21 is connected to multiplier 22. 23, and the multipliers 22. 23 is a low pass filter 24. 25 are connected respectively,
Furthermore, a comb filter 26 is provided at the subsequent stage. 27 are connected to each other. A phase detector 28, a loop filter 29, and a variable frequency oscillator 30 are connected in this order to the comb filter 27.

This variable frequency oscillator 30 is connected to a multiplier 23 and also to a multiplier 22 via a 90° phase shifter 31. Further, a signal for controlling the variable frequency oscillator 30 is input to a control signal input terminal 32 connected to the variable frequency oscillator 30 . Comb filter 26. The output terminal 33.27 is connected to the output terminal 33.27. 34 outputs a demodulated color difference signal.

The operation of the above configuration will be described below.

A low frequency conversion carrier color signal supplied from the ACC circuit 5 in FIG. 1 is input to the input terminal 2l. The carrier frequency of this low-pass conversion carrier color signal is approximately 627K in the case of PAL system.
H! , about 629KH for NTSC system! It is. This signal is applied to multiplier 22. In the multiplier 23, the signal supplied from the variable frequency oscillator 30 is multiplied by the signal supplied from the variable frequency oscillator 30. In the multiplier 22, the signal output from the variable frequency oscillator 30 is sent to The shifted signal is multiplied. A control signal supplied from the conversion controller 9 in FIG. 1 is input to the control signal input terminal 32.

The variable frequency oscillator 30 switches its oscillation center frequency using this control signal. For example, when the signal reproduced from a magnetic tape is in the PAL format, the oscillation center frequency is approximately 627KH! , in the case of the NTSC system, it is switched to about 629 KHx. Multiplier 22. 2
3, the sum and difference frequency components of the frequency components of the two signals to be multiplied are output, but the low-pass filter 2
4. At step 25, only the signal corresponding to the difference component, that is, the color difference signal demodulated to baseband, is passed. At this time, the output signal from the low-pass filter 24 is a B-Y signal,
The output signal from low pass filter 25 is the RY signal. The R-Y signal and the B-Y signal are each passed through a comb filter 26. 27 and the output terminal 33. It is output from 34. The RY signal is also supplied to a phase difference detector 28, where a demodulation phase error is detected. The demodulation phase error can be detected by integrating the signal of the burst portion of the RY signal. The detected demodulation phase error is given appropriate gain and low-pass characteristics by the loop filter 29 and fed back to the variable frequency oscillator 30 to control its oscillation frequency.

The low frequency conversion carrier color signal reproduced as described above is demodulated into a color difference signal according to the method.

The configuration shown in Fig. 2 is a color signal transmission method (NTSC method,
PAL system, etc.), but in order to support cases where the carrier color signal is FM modulated (when recording on a VTR, it is counted down to 1/4 and converted to low frequency) as in the SECAM system, the FM signal is A circuit for converting waves into color difference signals may be provided in parallel with the configuration shown in FIG. 2, and configured to switch between them.

Next, the color signal modulation circuit 8 shown in FIG. 1 will be explained in more detail. FIG. 3 is a block diagram showing an example of the configuration of the color signal modulation circuit 8 of FIG. 1.

In FIG. 3, signal input terminal 41. 42 includes a multiplier 43. 44, and then a bandpass filter 4
5 and 46 are connected respectively, and their outputs are sent to the adder 4.
7 is input. Further, the output of the reference frequency oscillator 48 is directly input to the multiplier 44, and the 90° phase shifter 4
9 to the multiplier 43. 50 is a control signal input terminal into which a signal for controlling the reference frequency oscillator 48 is input, and 51 is an output terminal for the modulated carrier color signal output from the adder 47.

The operation of the above configuration will be described below.

Input terminal 41. 42 are input with B-Y and RY color difference signals, respectively. The R-Y signal is sent to a multiplier 44,
Here, the reference frequency oscillator 48 output signal is multiplied. The BY signal is also sent to a multiplier 43, where it is multiplied by a signal obtained by shifting the phase of the output signal of the reference frequency oscillator 49 by 90 degrees using a 90' phase shifter 49. Control signal input terminal 5
0, a control signal supplied from the conversion controller 9 in FIG. 1 is input. The reference frequency oscillator 48 switches its oscillation frequency using this control signal. for example,
When outputting as a PAL system signal, the subcarrier frequency of the PAL system is about 4. Oscillates at 43MHr, NT
When outputting in the SC system, the subcarrier frequency of the NTSC system is about 3. 58MH! Switch to oscillate with .

Multiplier 43. 44, the sum component and the difference frequency component of the frequency components of the two signals to be multiplied are output.
Bandpass filter 45. At 46, only the subcarrier frequencies are passed. Bandpass filter 45. The output signals from 46 are added by an adder 47 and output from an output terminal 5l.

As described above, the color difference signals R-Y and B-Y are modulated into a desired carrier color signal under the control of the conversion controller 9 and output. Note that the configuration shown in Fig. 3 is similar to that shown in Fig. 2, and is based on a color signal transmission method in which the color difference signal is quadrature two-phase modulated and the color signal is transmitted.
NTSC, PAL, etc.), but in order to also support the SECAM system, the color difference signal must be
The M modulation circuit and the configuration shown in FIG. 3 may be provided in parallel and switched between them.

As described above, according to this embodiment, the low frequency conversion color signal reproduced from the magnetic tape is directly demodulated into the color difference signal, and after the field frequency and the number of scanning lines are appropriately converted, the carrier color signal is output. To provide a VTR which can reduce the number of frequency conversions compared to a conventional configuration, has a simple configuration and reduced circuit scale, and is capable of converting television formats with less signal deterioration. I can do it.

Effects of the Invention As described above, the present invention has excellent effects such as being able to realize a VTR that has a simple configuration, reduced circuit scale, and is capable of converting television formats with little signal deterioration. It is something that can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the main parts of a VTR according to an embodiment of the present invention, FIG. 2 is a block diagram showing an example of the configuration of a color signal demodulation circuit of the same VTR, and FIG. 3 is a block diagram showing the configuration of the color signal demodulation circuit of the same VTR. A block diagram showing an example of the configuration of a modulation circuit, Figure 4 is a conventional VTR.
FIG. 2 is a block diagram showing the structure of the main parts. 3... Luminance signal reproduction processing circuit, 5... Automatic color level control circuit, 6... Color signal demodulation circuit, 7... Field frequency/scanning line number conversion circuit, 8... Color signal modulation circuit .

Claims (1)

[Claims] 1. A video tape recorder that converts the luminance signal to FM and converts the color signal to the lower frequency side of the FM-converted luminance signal and records it on a magnetic tape. chrominance signal demodulation means for demodulating the signal into a chrominance signal; a luminance signal reproduction processing means for processing the FM luminance signal reproduced from the magnetic tape; A television in which a color signal is input, and a field frequency/scanning line number conversion means converts the field frequency and number of scanning lines of the television signal, and a color difference signal from the field frequency/scanning line number conversion means is recorded on a magnetic tape. and a color signal modulation means for converting the carrier color signal into a carrier color signal of a method different from that of the John signal.