JP2644054B2 - Method converter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system converter suitable for use in a video tape recorder (VTR).

[Prior Art] There are many regions that adopt the NTSC system or the PAL system as a television system. The NTSC video signal has a vertical frequency of 59.94 Hz and the number of scanning lines is 525 lines / frame. In contrast, PAL video signals have a vertical frequency of 50 Hz,
The number of scanning lines is 625 lines / frame.

Therefore, even if a reproduced video signal from an NTSC VTR is supplied to a PAL television receiver, a good image cannot be obtained. Therefore, conversion from one of the NTSC system and the PAL system to the other has been conventionally performed.

 FIG. 12 shows an example of a system conversion device.

In the figure, for example, a VTR supplied to an input terminal 51 is provided.
The NTSC video signal SVN reproduced by the Y / C separation circuit 52
Supplied to

The luminance signal YN separated by the Y / C separation circuit 52 is supplied to an A / D converter 54Y via a low-pass filter 53, and the luminance signal YN converted into a digital signal by the A / D converter 54Y is
For example, a memory circuit having two field memories
Supplied to 55Y.

In this memory circuit 55Y, among the six fields F1 to F6, F7 to F12,... (Shown in FIG. 13A) of the luminance signal YN,
Each of the two field memories has five fields F1 to F5, F7
... (Illustrated in FIG. B) are written. Each of the fields F1 to F5, F7 to F11,... Of the luminance signal YN written in the field memory is read out at a time of 1/50 Hz = 20 msec. At this time, the number of lines in each field is converted from 525 lines / 2 to 625 lines / 2 by a method such as double reading. As a result, the PAL-type luminance signal YP having a vertical frequency of 50 Hz and the number of scanning lines of 625 lines / frame is output from the memory circuit 55Y.
(Illustrated in FIG. C) is output. Where F1 '~ F5', F
7 'to F11',... Indicate the fields of the luminance signal YP, and the fields F1 to F5,.
.. Correspond to F7 to F11,.

The luminance signal YP output from the memory circuit 55Y is converted into an analog signal by the D / A converter 56Y, and then supplied to the adder 58 via the low-pass filter 57Y.

The color signal CN separated by the Y / C separation circuit 52 is supplied to a color demodulation circuit 60 via a band pass filter 59. The red difference signal RN-YN and the blue dye signal BN-YN output from the color demodulation circuit 60 are converted into digital signals by A / D converters 54R and 54B, respectively, and then supplied to memory circuits 55R and 55B. .

The memory circuits 55R and 55B are configured in the same manner as the above-described memory circuit 55Y. From these memory circuits 55R and 55B, a PAL red difference signal RP having a vertical frequency of 50 Hz and the number of scanning lines of 625 lines / frame is provided. −YP, blue difference signal BP−Y
P is output.

The color difference signals RP-Y output from the memory circuits 55R and 55B.
P and BP-YP are converted into analog signals by D / A converters 56R and 56B, respectively, and then supplied to a color modulation circuit 61 via low-pass filters 57R and 57B.

The color modulation circuit 61 performs insertion of a color burst and balanced modulation of a color difference signal in accordance with the PAL system.
As a result, the color modulation circuit 61 outputs a PAL color signal CP having a vertical frequency of 50 Hz and the number of scanning lines is 625 lines / frame.

The color signal CP output from the color modulation circuit 61 is supplied to an adder 58 and added to the luminance signal YP.
2 outputs a PAL video signal SVP.

The video signal SVN supplied to the input terminal 51 is supplied to a synchronization separation circuit 63. The horizontal synchronization signal HD and the vertical synchronization signal VD separated by the synchronization separation circuit 63 are supplied to a controller.
Supplied to 64. The operation of the memory circuits 55Y to 55B and the color modulation circuit 61 is controlled by the controller 64 as described above.

[Problem to be Solved by the Invention] By configuring as shown in FIG.
The format can be converted from the SC video signal SVN to the PAL video signal SVP.

However, according to such a system converter, three memory circuits 55Y to 55B are required for the luminance signal system and the color difference signal system, and the corresponding number of A / D converters 54Y to 54B, D / A The converters 56Y to 56B were required, and a simple and inexpensive configuration could not be achieved.

In view of the above, the present invention provides a system conversion device capable of realizing system conversion with a simple and inexpensive configuration.

Means for Solving the Problems According to the present invention, a color signal of one system having a first number of scanning lines is converted into a color modulation system equal to that of another system, and a color subcarrier frequency is an integral multiple of a horizontal frequency. A color signal processing means for converting the color signal into the color signal having the first number of scanning lines, and a color signal obtained by converting the luminance signal having the first number of scanning lines by the color signal processing means. Adding means for obtaining a video signal having the number of scanning lines, and scanning line number conversion for converting the number of scanning lines of the video signal obtained by the adding means to obtain another type of video signal having the second number of scanning lines Means.

[Operation] In the configuration described above, the scanning line number conversion means 32 includes, for example,
PAL video signal with NTSC scanning lines (525 lines / frame) is converted to PAL scanning lines (625 lines / frame)
Is converted into a PAL video signal having the number of scanning lines substantially coincident with each other, so that it is not necessary to provide a memory circuit for each of the luminance signal system and the color difference signal system as in the related art in order to convert the number of scanning lines.

In this case, since the color subcarrier frequency of the color signal C 'constituting the PAL video signal supplied to the scanning line number conversion means 32 is an integral multiple of the horizontal frequency, the scanning line number conversion means 32 For example, even if the same scanning line signal is output twice and the processing for increasing the number of scanning lines is performed, discontinuity of color signals does not occur.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. In this example, the system can be converted from the NTSC system to the PAL system. FIG. 1 shows a reproduction signal processing circuit.

Referring to FIG. 1, reference numeral 1 denotes a magnetic tape. As shown in FIG.
1, TB1, TA2, TB2,... Are formed. In this case, azimuth recording is being performed and recording track TA
The recording azimuths of the recording tracks TB1, TB2,... Are different from each other.

Each of the recording tracks TA1, TB1, TA2, TB2,. One field of the combined signal with the converted color signal CL) is recorded.

In FIG. 2, Tcn represents each recording track TA1, TB1, T
.. Are control tracks on which control signals are recorded corresponding to A2, TB2,..., And Tan is an audio track on which audio signals are recorded.

As shown in FIG. 3, the magnetic tape 1 is wound around the tape guide drum 2 over a range of approximately 180 °.
The vehicle is driven at a constant speed in the direction of the arrow by a capstan described later.

In FIG. 1, HA to HD are rotary magnetic heads. As shown in FIG. 3, the heads HA and HB and the heads HC and HD are arranged at an angular interval of 180 ° from each other.
, HC and HD and HD are arranged close to each other with an angular interval of several horizontal periods (αH).

The azimuth angles of the heads HA and HD correspond to the recording azimuths of the recording tracks TA1, TA2,. The azimuth angles of the heads HB and HC are as described above.
.. Correspond to the recorded azimuths of TB1, TB2,.

The heads HA and HC, and HB and HD, as shown in FIG.
It may be integrally formed as a so-called double azimuth head.

These heads HA to HD rotate at a constant speed in the direction of the arrow. In this case, the output signal is NT
When the SC video signal SVN is obtained (at the time of non-system conversion), the video signal is rotated at 1800 rpm. On the other hand, when obtaining a PAL video signal SVP as an output signal (at the time of format conversion)
Is set to rotate at 1500 rpm.

 FIG. 5 is a diagram showing a tape running system.

In the figure, a head (FG head) 10 constituting a frequency generator FG attached to the rotating shaft of a drum motor 101
The frequency signal output from the output signal 2 and proportional to the number of rotations of the heads HA to HD is amplified by the FG amplifier 103 and then output from the speed detector 1.
Supplied to 04. From the speed detector 104, the head HA ~
A signal having a level corresponding to the number of rotations of the HD is output, and this signal is supplied to the comparator 105.

EDN and EDP have heads HA to HD of 1800 rp, respectively.
This is a signal having the same level as that of the signal obtained from the speed detector 104 when rotating at m and 1500 rpm. These signals EDN and EDIP are supplied to fixed terminals on the N and P sides of the changeover switch 106, respectively. The changeover switch 106 is connected to the N side during non-system conversion, and is connected to the P side during system conversion.

The output signal of the changeover switch 106 is supplied to the comparator 105 as a reference signal. The signal output from the comparator 105 is supplied to the adder 107 as a speed error signal.

A pulse signal having rotation phase information of the heads HA to HD output from a head (PG head) 108 constituting a pulse generator (PG) attached to the rotation shaft of the drum motor 101 is amplified by a PG amplifier 109. Later waveform shaping circuit 1
After the waveform is shaped at 10, the waveform is supplied to the phase comparator 111.
As described above, during non-system conversion and system conversion, the heads HA to HD rotate at 1800 rpm and 1500 rpm, respectively, so that the frequency of the pulse signal at each time is 30 Hz and 25 Hz.

Reference numeral 112 denotes a crystal oscillator, and an oscillation signal from this is supplied to the frequency divider 113. A frequency-stable signal of 30 Hz is output from the frequency divider 113, and this signal is supplied to the N-side fixed terminal of the changeover switch 114.

Reference numeral 115 denotes a crystal oscillator, and an oscillation signal from this is supplied to the frequency divider 116. A frequency-stable signal of 25 Hz is output from the frequency divider 116, and this signal is supplied to the fixed terminal on the P side of the changeover switch 114.

The changeover switch 114 is connected to the N side during non-system conversion, and connected to the P side during system conversion. The output signal of the changeover switch 114 is supplied to the phase comparator 111 as a reference phase signal. The signal output from the comparator 111 is supplied to the adder 107 as a phase error signal.

The adder 107 adds the speed error signal and the phase error signal.
The signal is supplied as a control signal to the driver 117, and the driver 117 drives the drum motor 101.

As a result, the heads HA to HD are 18
The motor is rotated at a rotation speed of 00 rpm and a fixed phase, and is rotated at a rotation speed of 1500 rpm and a fixed phase at the time of system conversion.

201 is a capstan, and this capstan 2
01 and the frequency signal proportional to the number of rotations of the capstan 201 output from the FG head 202 constituting the frequency generator (FG) attached to the rotating shaft are amplified by the FG amplifier 203 and supplied to the speed detector 204 Is done. From the speed detector 204, a signal having a level corresponding to the rotation speed of the capstan 201 is output, and this signal is supplied to a comparator 205.

EC is a signal having the same level as the level of the signal obtained from the speed detector 204 when the magnetic tape 1 is run at a speed necessary for normally reproducing the NTSC video signal SVN from the magnetic tape 1. This signal EC is supplied to the comparator 205 as a reference signal. The signal output from the comparator 205 is supplied to the adder 206 as a speed error signal.

Also, recording tracks TA1, reproduced by the control head 207 from the control tracks Tcn of the magnetic tape 1,
The control signal of 30 Hz having the positional information of TB1, TA2, TA2,... Is amplified by the CTL amplifier 208, is waveform-shaped by the waveform shaping circuit 209, and is supplied to the phase comparator 210. The phase comparator 210 is supplied with a phase-stable 30 Hz signal output from the frequency divider 113.

The signal output from the comparator 210 is supplied to the adder 206 as a phase error signal. The adder 206 adds the speed error signal and the phase error signal, and the added signal is supplied to a capstan motor driver 211 as a control signal, and the capstan motor 212 is driven by the driver 211.

As a result, the magnetic tape 1 receives the NTSC video signal SY.
It is made to run at a constant speed required for normal reproduction of N.

In this way, the rotation speeds and phases of the heads HA to HB and the running speed of the magnetic tape 1 are controlled, and during non-system conversion and system conversion, the heads HA to HD move the recording tracks TA1, TB1, TA2, TB2 of the magnetic tape 1. .. Are scanned as follows.

[At the time of non-system conversion] In a certain vertical period (1/60 sec), the heads HA and HC scan the recording tracks TA1, TA2,... (See FIG. 2). Heads HB and HD
Scan recording tracks TB1, TB2,... (See FIG. 2). As a result, reproduced signals are output from the heads HA and HB as shown in FIG. 6A.

[At the time of system conversion] During a certain vertical period (1/50 sec), the heads HA and HC scan the trajectories ta1, ta2,... (See FIG. 2). And HD are locus,
.. (see FIG. 2). As a result, the heads HA and HB output the signals shown in FIG.
A reproduced signal is output as shown in FIG. 7, and a reproduced signal is output from the heads HC and HD as shown in FIG.

Returning to FIG. 1, the reproduction signals from the heads HA and HC are supplied to the fixed terminals on the a and b sides of the changeover switch 4 via the reproduction amplifiers 3A and 3C, respectively.
Reproduction signals from the heads HB and HD are supplied to the a side and b of the changeover switch 5 via the reproduction amplifiers 3B and 3D, respectively.
Supplied to the fixed terminal on the side. The output signals of the changeover switches 4 and 5 are supplied to the fixed terminals on the a and b sides of the changeover switch 6, respectively.

The changeover switches 4 and 5 are supplied with a changeover control signal Ssw, and the switching is controlled as follows during non-system conversion and system conversion. That is, at the time of non-system conversion, it is kept connected to the a side. In addition, at the time of system conversion, the head HA or HB moves along the trajectories ta1 to ta2,
When scanning ta5 to ta7, ..., it is connected to the a side,
The head HC or HD has trajectories tb2 to tb4, tb7 to tb9,.
Is connected to the b side when scanning.

Further, a head switching pulse RFSW is supplied to the changeover switch 6, and the heads HA and HC are connected to the side a during the vertical period when the heads HA and HC are scanning over the magnetic tape 1, and the heads HB and HD are connected.
Are connected to the b side during the vertical period during which the scanning is performed on the magnetic tape 1.

Since the switching of the changeover switches 4 to 6 is controlled in this way, the changeover switch 6 outputs the following signals.

That is, a signal having a vertical frequency of 60 Hz is output during non-system conversion (see FIG. 6A), and a signal having a vertical frequency of 50 Hz is output during system conversion (see FIG. D). The recording tracks TA1, TB1, TA2, TB2,...
Since the video signal SVN of the NTSC system is originally recorded in, the number of scanning lines is 525 lines / frame both during non-system conversion and during system conversion.

The output signal of the changeover switch 6 is supplied to a high-pass filter 7 to extract a modulated luminance signal YFM. The modulated luminance signal YFM is supplied to an FM demodulator 10 via a series circuit of an AGC circuit 8 and a limiter 9 and demodulated. Is done.

The luminance signal Y output from the FM demodulator 10 is supplied to an adder 14 through a series circuit of a de-emphasis circuit 11, a low-pass filter 12, and a noise canceller 13.

The output signal of the changeover switch 6 is a low-pass filter.
15 supplied to the low-frequency conversion color signal CL (color subcarrier frequency is
f SL) is extracted. The low-frequency conversion color signal CL is supplied to the frequency converter 17 via the ACC circuit 16, and the color signal C frequency-converted by the frequency converter 17 is supplied to the N-side of the switch 19 via the band-pass filter 18. It is supplied to the fixed terminal.

The luminance signal Y output from the noise canceller 13 is supplied to a sync separation circuit 20, where a horizontal sync signal HD (horizontal frequency is fH) is separated.
Supplied to 1. The AFC detector 21 includes a voltage controlled oscillator 22
Is supplied to the frequency divider 23 after being divided by n, and the frequency is compared with the horizontal synchronizing signal HD. And this AFC detector
The comparison error signal from 21 is supplied to a voltage controlled oscillator 22 as a control signal.

The output signal of the voltage controlled oscillator 22 is
After the frequency division, it is supplied to the frequency converter 25.

Here, the color subcarrier frequency f SL and the horizontal frequency f H
Satisfies the following relationship:

fSL = nfH / m At the time of system conversion, the chrominance subcarrier frequency fSL and the horizontal frequency fH decrease at the same rate, so that the above relationship is satisfied also at this time.

Therefore, the frequency of the signal supplied from the frequency divider 24 to the frequency converter 25 is fSL both during non-system conversion and during system conversion.

26 is a crystal oscillator that generates a signal having a frequency f SC = 3.58 MHz, and 27 is a crystal oscillator that generates a signal having a frequency that is an integral multiple of the horizontal frequency f H, in this example, a frequency f SC ′ = 3.69 MHz It is. The frequency signals from the crystal oscillators 26 and 27 are supplied to fixed terminals on the N and P sides of the changeover switch 28, respectively. The changeover switch 28 is connected to the N side during non-system conversion, and is connected to the P side during system conversion.

The frequency signal from the changeover switch 28 is supplied to the frequency converter 25. The frequency converter 25 outputs the frequency f SC + f SL during non-system conversion, and the frequency f S during system conversion.
A frequency signal of C ′ + f SL is output, and this frequency signal is supplied to the frequency converter 17.

Therefore, the color signal C output from the frequency converter 17
Color subcarrier frequency is f SC = 3.58 MH during non-system conversion
z, and fSC ′ = 3.69 MHz at the time of system conversion.

Here, the color subcarrier frequency f SC at the time of non-system conversion is 455f
Although H / 2 is not an integral multiple of the horizontal frequency fH, the color subcarrier frequency fSC 'at the time of system conversion is 282fH, which is an integral multiple of the horizontal frequency fH. That is, when the horizontal synchronizing signal HD is as shown in FIG. 7C, the color subcarriers at the time of non-system conversion are as shown in FIG. A, and the color subcarriers at the time of system conversion are as shown in FIG. become.

The color signal C output from the band-pass filter 18
Is supplied to the APC detector 29 and the burst gate pulse PBG
Is used to extract the color burst. The APC detector 29 is supplied with a frequency signal from the changeover switch 28,
The frequency is compared with the color burst. And this APC
The comparison error signal from the circuit 29 is supplied to the voltage controlled oscillator 22 as a control signal. As a result, the color subcarrier frequency of the color signal C output from the frequency converter 17 is stabilized to f SC during non-system conversion and to f SC ′ during system conversion.

The color signal C output from the band-pass filter 18
Is supplied to the color signal processing circuit 30, and the color signal processing circuit 30
Is supplied with a frequency signal from the changeover switch 28. The color signal processing circuit 30 is operated at the time of system conversion. In the color signal processing circuit 30, the color signal C is demodulated to obtain a color difference signal, and color burst insertion and balanced modulation of the color difference signal are performed in accordance with the PAL system.

As a result, at the time of system conversion, the color signal processing circuit 30 outputs a PAL color signal C 'having a vertical frequency of 50 Hz, 525 scanning lines / frame, and a color subcarrier frequency of 3.69 MHz. Is supplied to the P-side fixed terminal of the changeover switch 19.

The changeover switch 19 is connected to the N side during non-system conversion, and is connected to the P side during system conversion. Therefore,
This switch 19 outputs an NTSC color signal having a vertical frequency of 60 Hz, 525 scanning lines / frame, and a color subcarrier frequency of 3.58 MHz during non-system conversion, and a vertical frequency of 50 Hz during system conversion. PAL color signal C 'having 525 scanning lines / frame and a color subcarrier frequency of 3.69 MHz
Is output.

The output signal of the changeover switch 19 is supplied to the adder 14 and added to the luminance signal Y output from the noise canceller 13. The adder 14 outputs an NTSC video signal obtained by adding the luminance signal Y having a vertical frequency of 60 Hz and the number of scanning lines of 525 lines / frame and the NTSC color signal at the time of non-system conversion.
SVN is output, and at the time of format conversion, a video signal SV in which the luminance signal Y having a vertical frequency of 50 Hz and the number of scanning lines is 525 lines / frame and the PAL color signal C ′ are added is output.

The video signal SV output from the adder 14 is supplied to a changeover switch 31.
Of the scanning line converter 32
Supplied to The scanning line converter 32 operates at the time of system conversion.

As described above, at the time of system conversion, the adder 14 outputs a video signal having a vertical frequency of 50 Hz and the number of scanning lines of 525 lines / frame. The video signal is converted so that the number of scanning lines becomes 625 lines / frame. Here, the rate of increase is (625-525) / 5
Since 25 = 1 / 5.25, it is sufficient to add one scanning line to every 5.25 lines.

FIG. 8 shows a configuration example of the scanning line converter 32. In this example, the same scanning line is successively read out twice in a ratio of one out of five, and the scanning line is added.

In the figure, a video signal SV of 525 scanning lines / frame supplied to an input terminal 301 at the time of system conversion is converted by an A / D converter 30.
After being converted into a digital signal in 2, it is supplied to the line memories 303 and 304 as a write signal. These line memories 303 and 304 store 5 scan lines and 7
It has a storage capacity for scanning lines.

Writing and reading of the line memories 303 and 304
Write control circuit 305 and read control circuit 3 respectively
Controlled by 06.

In this case, ten scanning lines of the video signal SV (shown in FIG. 9A) are regarded as one unit, and the first to fifth five scanning lines are written in the line memory 303, and the fourth to tenth scanning lines are written. Seven scanning lines are written to the line memory 304 (illustrated in FIGS. C and D). Then, 12 written to the line memories 303 and 304
The scanning line segment is read out in one unit period (see FIG.
F).

Read signals from the line memories 303 and 304 are supplied to fixed terminals on the a and b sides of the changeover switch 307, respectively. The changeover switch 307 is connected to the line memory 303
And when 304 is in the read state,
Side and b side. With this, the changeover switch
From 307, a video signal SVP (shown in FIG. 7G) with an increased number of scanning lines is output. The color subcarrier frequency of the color signal C ′ included in the video signal SVP is approximately 4.43 MHz (3.69 MHz × 6 /
5)

By the way, if the number of scanning lines is increased at a rate of one out of every five, the number of scanning lines is finally 630 / frame. In this example, during a certain period outside the effective screen,
Instead of the above-described operation of converting the signal for 10 scanning lines into a signal for 12 scanning lines and outputting the signal, the signal for 10 scanning lines is controlled to be output as it is.
The number of scanning lines of the video signal SVP output from 7 is set to 625 lines / frame.

The video signal SVP output from the changeover switch 307 is D /
Output terminal 30 after being converted to analog signal by A converter 308
Supplied to 9.

The video signal SV supplied to the input terminal 301 is supplied to a synchronization separation circuit 310, and the horizontal synchronization signal HD and the vertical synchronization signal VD separated by the synchronization separation circuit 310 are supplied to a controller 311. The operation of the write control circuit 305, the read control circuit 306, and the changeover switch 307 is controlled by the controller 311 as described above.

Here, the color signal C 'included in the video signal SV is of the PAL system. That is, this color signal C ′ is
The sum of the balanced modulation of the color subcarrier of 0 ° phase by −Y and the balanced modulation of the color subcarrier of 90 ° phase and −90 ° phase for each scanning line by the red difference signal RY is added. It is formed. A color burst having a phase of ± 135 ° from the BY axis is added to each scanning line in accordance with the switching of the phase of the red color difference signal RY. FIG. 9B shows the phase of the color burst of each scanning line in the video signal SV.

As described above, five scanning lines are written into the line memory 303 and seven scanning lines are written into the line memory 304, and are sequentially read out. Therefore, the phase of the color burst included in the video signal SVP is as shown in FIG. , And the continuity of the color burst phase is maintained.

Note that the combinations of the memory capacities of the line memories 303 and 304 are not limited to those in the above-described example. However, by combining them as in the above-described example, the scanning lines are reversed in the front-rear direction (see the portion e → d in FIG. ) Can be reduced.

Further, as described above, the chrominance subcarrier frequency f SC ′ in the video signal SV is set to an integral multiple of the horizontal frequency f H (see FIGS. 7B and 7C). Is kept. For example, line memory 30
The phases of the color subcarriers in the output signals 3 and 304 are as shown in FIGS. 10B and 10C, and the color subcarriers in the video signal SVP are stored in the line memories 303 and 304 as shown in FIG.
Are continuous even when the output signal is switched. FIG. 7A shows a control signal of the changeover switch 307.

The configuration of the scanning line converter 32 is not limited to the above. For example, from the vertical positional relationship between 525 scan lines before conversion and 625 scan lines after conversion,
625 scanning line signals may be formed by weighting the 25 scanning line signals. Also in this case, the configuration can be made using a small-capacity line memory.

Returning to FIG. 1, the PAL video signal SVP having a vertical frequency of 50 Hz and the number of scanning lines of 625 / frame output from the scanning line converter 32 at the time of system conversion is supplied to the P-side fixed terminal of the changeover switch 31. Supplied.

The changeover switch 31 is connected to the N side during non-system conversion, and connected to the P side during system conversion. The output signal of the changeover switch 31 is led to an output terminal 33.

This embodiment is configured as described above. At the time of non-system conversion, the changeover switches 106 and 114 (see FIG. 5) are connected to the N side, so that the rotation speeds of the heads HA to HD become 1800 rpm,
The adder 14 is supplied with a luminance signal Y having a vertical frequency of 60 Hz and the number of scanning lines is 525 lines / frame.
Through the N side of 19, an NTSC color signal having a vertical frequency of 69 Hz, a scanning line number of 525 lines / frame, and a color subcarrier frequency of 3.58 MHz is supplied. Then, the NTSC video signal SVN output from the adder 14 is output to the output terminal 33 via the N side of the changeover switch 31.

Further, at the time of system conversion, since the changeover switches 106 and 114 are connected to the P side, the number of rotations of the heads HA to HD becomes 1500
rpm, and the adder 14 has a vertical frequency of 50 Hz and a scan line of 5
25 luminance signals Y are supplied, and the changeover switch 19
Vertical frequency is 50Hz and the number of scanning lines is 525 /
A PAL color signal C ′ having a frame and color subcarrier frequency of 3.69 MHz is supplied. The video signal SV output from the adder 14 is supplied to the scanning line converter 32. The vertical frequency output from the scanning line converter 32 is 50 Hz, and the number of scanning lines is 62.
A PAL video signal SVP having 5 lines / frame and a color subcarrier frequency of about 4.43 MHz is output to the output terminal 33 via the P side of the changeover switch 31.

As described above, according to this example, at the time of system conversion, the adder 14
The scanning line converter 32 converts the number of scanning lines to the output video signal SV to obtain a PAL video signal SVP. Since it is not necessary to provide each of the signal systems, the circuit configuration can be simplified and the configuration can be made at low cost.

In this case, since the color subcarrier frequency f SC ′ in the video signal supplied to the scanning line converter 32 is set to an integral multiple of the horizontal frequency f H, the PAL output from the scanning line converter 32
The continuity of the color subcarrier frequency in the video signal SVP of the system is maintained. The scanning line converter 32 has a line memory 30.
3 is written with 5 scanning lines and the line memory 304 is written with 7 scanning lines, and is read out in order.
, The continuity of the color burst phase included in is maintained.

Further, according to this example, at the time of system conversion, the heads HA to HD are used.
The vertical frequency is converted by controlling the number of rotations, and the scanning line converter 32 only converts the number of scanning lines. That is, the scanning line converter 32 is, for example,
The configuration can be made using a small-capacity memory having a storage capacity of seven lines, and system conversion can be easily performed using a small-capacity memory.

In the embodiment described above, the NTSC video signal SVN is recorded on the magnetic tape 1, and the PAL
It is possible to output the SVP of the video signal of the PAL system, but on the contrary, the video signal S of the PAL system is
The video signal SVN of the NTSC system can be output in the same manner from the VP recorded.

That is, the rotation speed of the heads HA to HD is increased from 1500 rpm to 1800 r.
The vertical frequency is converted from 50Hz to 60Hz, changed to pm. In addition, the number of scanning lines is 625 /
Frames are converted to 525 lines / frame.

Also in this case, before the scan line conversion, the color subcarrier frequency is frequency-converted so as to be an integral multiple of the horizontal frequency. Since the color burst in the NTSC system has a constant phase, the scanning line converter 32 does not need to perform the process of continuing the color burst phase as in the above-described PAL system.

Further, in the above-described embodiment, the four heads HA are used in order to prevent a decrease in the reproduction output level due to a track king shift when the number of rotations of the head is changed at the time of system conversion.
To HD, the reproduction output of these heads is appropriately switched. For example, two heads HA,
Tracking may be performed by using only HB and swinging these heads HA and HB in bimorph.

In the above embodiment, the vertical frequency is converted by controlling the number of rotations of the heads HA to HD. However, the same applies to the conversion using a memory circuit as shown in FIG. Can be applied to This second
11, parts corresponding to those in FIG. 12 are denoted by the same reference numerals.

In the example of FIG. 11, the NTS separated by the Y / C separation circuit 52
The C-system color signal CN is supplied to the color signal processing circuit 71 via the band-pass filter 59. The operation of the color signal processing circuit 71 is controlled by the controller 64. This color signal processing circuit
At 64, the color signal CN is demodulated, and the demodulated color difference signal is modulated to form a PAL color signal CP '. In this case, the color subcarrier frequency of the color signal CP 'is set to an integral multiple of the horizontal frequency of the video signal SVN, for example, 3.9 MHz.

The color signal CP 'output from the color signal processing circuit 71 is supplied to the adder 72 and added to the luminance signal YN. The vertical frequency output by the adder 72 is 60 Hz, and the number of scanning lines is 52
Five / frame video signals are converted to digital signals by the A / D converter 54Y and supplied to the memory circuit 55Y. The conversion of the vertical frequency and the number of scanning lines are performed by the memory circuit 55Y, and a PAL video signal SVP having a vertical frequency of 50 Hz and the number of scanning lines of 625 / frame is output to an output terminal 62.

When the number of scanning lines is converted by the memory circuit 55Y, it is necessary to perform the writing and reading processing of the memory in consideration of the continuity of the color burst as in the case of the scanning line converter 32 in FIG. . In addition, since the color subcarrier frequency of the color signal CP 'is an integer multiple of the horizontal frequency of the video signal SVN, the color subcarrier frequency in the video signal SVP is continuous.

According to the example shown in FIG. 11, since a single memory circuit for converting the vertical frequency and the number of scanning lines can be formed, the configuration can be made simpler and cheaper than the example shown in FIG.

[Effects of the Invention] As described above, according to the present invention, the number of scanning lines conversion means converts the number of scanning lines not in the state of the luminance signal and the color difference signal but in the state of the video signal as in the related art. It is not necessary to provide a scanning line number conversion means for each of the luminance signal system and the color difference signal system as in the related art, so that the configuration can be made simply and inexpensively. In this case, the color subcarrier frequency in the video signal supplied to the scanning line number conversion means is an integral multiple of the horizontal frequency, so the color subcarrier frequency in the video signal of another system output from the scanning line number conversion means. Are not discontinuous.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a reproduction signal processing system, FIG. 2 is a diagram showing a recording track pattern of a magnetic tape, FIG. 3 is a configuration diagram of a rotary head device, FIG. 4 is a configuration diagram of a magnetic head, FIG. FIG. 6 is a diagram of a tape traveling system, FIG. 6 is a diagram for explaining a reproduced signal, FIGS. 7 and 10 are diagrams for explaining a color subcarrier, FIG. 8 is a diagram of a scanning line converter, and FIG. FIG. 11 is a diagram illustrating the operation of a line converter, FIG. 11 is a configuration diagram of a system converter, FIG. 12 is a configuration diagram of a conventional system converter, and FIG. DESCRIPTION OF SYMBOLS 1 ... Magnetic tape 4-6,19,28,31,106,114 ... Switch 14 ... Adder 30 ... Color signal processing circuit 32 ... Scanning line converter HA-HD ... Rotating magnetic head

Claims (1)

(57) [Claims] 1. A color signal of one system having a first number of scanning lines, the color signal of which is equal to that of another system, and the color subcarrier frequency is an integral multiple of the horizontal frequency, and the first number of scanning lines is A color signal processing unit that converts the color signal into a color signal having the first number of scanning lines; and a luminance signal having the first number of scanning lines, and a color signal obtained by being converted by the color signal processing unit. Adding means for obtaining a video signal having the same, and scanning line number converting means for converting the number of scanning lines of the video signal obtained by the adding means to obtain a video signal of the other system having the second number of scanning lines. A system conversion device characterized by the above-mentioned.