JPS6012696B2 - Recording media feed speed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a recording medium feed speed control device that enables recording and reproduction at two different speeds in a recording and reproducing device such as a magnetic green image reproducing device.

Generally, in a magnetic mirror image playback device that uses a rotating magnetic head to record signals on a magnetic tape, video signals are recorded in an oblique direction different from the tape traveling direction.

Therefore, a large number of diagonal video tracks are formed one after another on a tape running at a constant speed. In order to read the video signal from the video track recorded in this way, run the tape with the same recording as when recording.
Furthermore, it is necessary to ensure that the rotating head correctly scans the image track. In order to perform this correct scanning, the tape must be run at a constant speed during recording, and at the same time,
Control signals are recorded at one end of the tape in correspondence with the video tracks. As this control signal, for example, a 30 Hz pulse synchronized with one frame frequency of the video signal, that is, a vertical synchronizing signal divided by 1'2, is used. During reproduction, this control signal is reproduced, and the rotational phase of the rotary head is controlled using this as a clue, so that the head correctly scans the video track. In this way, in this type of magnetic recording/playback device, the tape is fed at a constant speed, and at the same time, control signals are recorded in addition to video signals corresponding to the video tracks. A signal is used to control the rotary head to obtain a reproduced video signal.

By the way, the tape speed is determined by specifications such as the S/N (signal to noise ratio) and frequency characteristics of the reproduced signal.
On the other hand, even if the quality of the reproduced signal is slightly improved, there may be cases where it is desired to lengthen the playback time of the tape depending on the purpose of use.

For example, if you play a one-hour tape at a normal tape feed speed,
Depending on the purpose, you may want to use this as a 2-hour tape. In such a case, if the tape speed during normal use is set to the standard speed, the tape speed may be set to 1/2 of the standard speed when used for 2 hours. Even when video signals are recorded at two different speeds in this way, the method for recording them on tape is the same.

That is, the video track is formed diagonally, and the control signal for controlling the rotation of the rotary head is recorded at the edge of the tape. However, since the tape speeds are different between the two, the magnetization patterns formed on the tapes are different between the two, for example, the pitch of the magnetization patterns is in a ratio of 2:1. These control signals with different magnetization patterns are used to control the rotation of the rotary head during reproduction, but the speed of the magnetic tape during reproduction must be the same as that during recording.

If this speed is different from that during recording, a regular control signal cannot be obtained, the rotational phase of the rotary head is disturbed, and a regular video signal cannot be obtained. During recording, the tape speed is arbitrarily selected by the operator, but if the tape speed is manually selected during playback, the operation becomes extremely complicated.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a recording medium feed speed control device that automatically makes the tape speed during playback the same as the tape speed during recording.

Next, one embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, 1 is a magnetic tape that is fed at either the standard feed speed or the half-speed feed speed 1'2;
2 and 3 are both magnetization patterns of control signals for controlling the rotation of the rotary head recorded on the lower end of the magnetic tape, 4 is a capstan for feeding the magnetic tape 1 in the direction of arrow A, and 5 is a magnetization pattern for controlling the rotation of the rotary head. A capstan motor is driven. 6 is a feed speed changeover switch that switches the power applied to the capstan motor 5 in two ways depending on the feed speed of the magnetic tape 1. 7 is connected to the NP side terminal NP of the feed speed changeover switch 6. 8 is the second power source of the voltage lug 2 connected to the SP side terminal SP of the feed rate selector switch 6; 9 is a switch switching circuit for switching the feed rate selector switch 6; If the feed rate switching switch 6 is a relay, for example, the switch changeover circuit 9 can be constituted by a transistor or the like that turns on and off the drive coil of the relay according to the voltage applied to the base. In addition, 10 is a magnetic tape 11 and the control signal is transmitted to a magnetization pattern 2,
3 is a control head for recording or reproducing signals from this, 11 is a recording/playback switch for switching the circuit connected to this control head-01 between recording and playback, and 12 is a recording/playback switch. This is a control signal generation circuit connected to the recording side terminal R of the changeover switch 11.

In this control signal generation circuit 12, 13 is a video signal input terminal, 14 is a synchronization separation circuit that separates a vertical synchronization signal from the video signal from the input state 13; '2 frequency divider circuit,
1 6 is a monomulti that generates control signals b with different duties (pulse width ratios) for the two feed speeds from the output a of the 1'2 frequency divider circuit 15, 17 is a power source for the monomulti 16, and 18 is a speed switch This is a second feed rate changeover switch that is switched between the NP side terminal NP and the SP side terminal SP by a signal from the command input terminal 19, and this second feed rate changeover switch 18 has a resistance value of The power source 17 is applied to the monomulti 16 by switching between the first and second time constant resistors 20 and 21 of R2 and R2.
Reference numeral 22 denotes a feed speed control device according to an embodiment of the present invention, which is connected to the playback side terminal P of the recording/playback switch 11.

In this feed rate control device 22, reference numeral 23 indicates that the control head 10 controls the magnetization patterns 2 and 3 of the control signal.
A first amplifier 24 serves as a first pulse detection circuit that amplifies and detects only positive polarity pulses out of the output of the pulse amplifier 23;
5 is a second amplifier as a second pulse detection circuit that amplifies and detects only the negative polarity pulse from the output of the pulse amplifier 23; 26 is the output d of the first amplifier 24 as an R input;
A flip-flop serves as a control signal reproducing circuit that takes the output e of the amplifier 25 as an S input and generates a signal having the same duty as the control signal. 27 is a low-pass filter that serves as a smoothing circuit that smoothes the output of the flip-flop 26. , 28 is a switch switching circuit which applies a signal from the speed switching command input terminal 19 to the switch switching circuit 9 via the recording side terminal R during recording, and applies the output of the low-pass filter 27 via the playback side terminal P during playback. A second recording/playback switching switch 29 in addition to 9 is composed of the above-mentioned switch switching circuit 9 and feed speed switching switch 6, and a low frequency filter switch 27.
This is a feed speed switching circuit that switches the feed speed between standard speed and half speed feed speed according to the output of the feed speed. Next, the operation of this circuit will be explained with reference to FIG. 2, which shows waveform diagrams of various parts of the circuit.

The magnetic tape 1 is fed at a constant speed in the direction of arrow A in the figure by a capstan 4 driven by a capstan motor 5. Here, when the feed speed is the standard speed, the feed speed selection switch 6 is set to the NP side terminal NP by the switch changeover circuit 9.
The power supply 7 supplies the voltage E to the capstan motor 5. Also, when the magnetic tape feed speed is half speed, which is 1/2 of the standard speed, the feed speed selection switch 6 is switched to the SP side terminal SP, and the voltage E2 is supplied from the power source 8 to the capstan motor 5. be done. Now, during recording, the recording/reproducing changeover switches 11 and 28 are switched to the recording side terminal R.

At this time, the tape speed is switched by the operator inputting a speed switching command signal to the speed switching command input terminal 19.
is switched to either the NP side terminal NP or the SP side terminal SP. A video signal is applied to the video signal input terminal 13, and then a vertical synchronization signal is separated from this video signal by a synchronization separation circuit 14.

The separated vertical synchronization signal is further transmitted to circuit 1 for the next 1/2 minute.
The frequency is divided by 1/2 by 5, and 3 as shown in Figure 2a.
Pulse signal a on day 0 2 is obtained. Next, this signal a is converted to a control signal b shown in the figure b by the monomulti 16.
becomes. The polarity of this signal b is reversed between positive and negative within one period, and when this signal is supplied to the control head 101 via the recording side terminal R of the recording/reproduction switch 11, the control head 101 The polarity of the current is also reversed. Therefore, on the magnetic tape 1 there is a
The period indicated by the symbol N is recorded as a north pole, for example,
Periods marked with the symbol S are recorded as south poles. Incidentally, at the same time, a video signal is recorded diagonally on another part of the tape by a rotating head. Now, control signal b
The generation method will be explained in more detail.

When the magnetic tape 1 is fed and recorded at the standard speed, the second feed speed selection switch 18 is switched to the NP side terminal NP, and the monomulti 16 has a first time that determines the delay time. A power source 17 is applied via a constant resistor 20. Further, when recording by feeding the magnetic tape 1 at half speed, the feed rate switching switch 18 is switched to the SP side terminal SP, and the monomulti 16 is connected via the second time constant resistor 21. Power source 17 is applied. Here, the resistance value R. of these resistors 20 and 21 is determined. , R2 are different from each other, the time width T of the output signal b of the monomulti 16 shown in FIG. Width T2 means T, Ki T2
becomes. However, both time widths T, and L are 1/2 of the above
Period L of vertical synchronization signal divided by 1/2 by frequency dividing circuit 15 =
It will be smaller than 1/30 second (T.<To, T2<
L). Ultimately, in either case, the output pulse signal b of the monomulti 16 has the same repetition period, but the duty is different between the two. Therefore, during recording, the feed speed selector switches 6 and 18 are set to N.
If the switch is switched to the P side terminal NP, a control signal as shown in the magnetization pattern 2 in FIG. When the switch is switched to , a control signal as shown in magnetization pattern 3 in FIG. 1 is recorded. In these magnetization patterns, the vertical solid line indicates the position where the S pole transitions to the N pole, and the vertical broken line indicates the position where the N pole transitions to the S pole. Next, during reproduction, the recording/reproduction changeover switches 11 and 28 are switched to the reproduction side terminal P, and from the magnetization pattern 2 or 3 recorded as described above, the output end of the control head 10 receives the second
As shown in Figure c, a signal c is obtained in which a positive pulse + is generated at the time of transition from the S pole to the N pole, and a negative pulse - is generated at the time of transition from the N pole to the S pole. This signal c
is used to control the rotation of the rotary head during reproduction, but its explanation will be omitted here.

Note that only the positive polarity pulse 10 is used to control the rotation of the rotary head, and the negative polarity pulse - is used together with the positive polarity pulse + to switch the feed rate, but is not used to control the rotation of the rotary head. . The output signal c of the control head 10 is amplified by the pulse amplifier 23 to an unnecessary level, and then outputted to the next amplifiers 24 and 25.
be done. In the first amplifier 24, only the positive polarity pulse 10 shown in FIG. 2c is amplified to obtain a signal as shown in FIG. 2d. Further, in the second amplifier 25, only the negative polarity pulse shown in FIG. 2c is amplified to obtain a pulse as shown in FIG. 2e. Next, the output d of the first amplifier 24 is input to the R input of the flip-flop 26, and the output e of the second amplifier 25 is input to the S input of the flip-flop 26.

Flip-flop 26 has its output at voltage E with respect to its R input. The structure is such that the output is zero for input to the S input, and the first amplifier 24
By applying the output pulse of the second amplifier 25 as described above, the output f shown in FIG. 2 f is obtained. The output of the flip-flop 26 is then passed through a low-pass filter 27 to form a smooth DC voltage V. This DC voltage V is the average voltage of the output of the flip-flop 26, and the output f
When the repetition period of is to and the pulse width is t, the DC voltage V is given by (t/to)·Eo, and is the voltage shown by the broken line in FIG. 2f. This DC voltage V is applied from the playback terminal P of the recording/playback switch 28 to the next switch/switch circuit 9. Here, if the tape speed at the time of recording was the standard speed, and the playback speed was the standard speed, to=T
o, t=T, and if the playback speed is half-speed feed speed, then t.

=2To, t=2T. Therefore, the DC voltage V is V=(t/L)·E for any playback speed. =(
T,/T. )・E. becomes. Next, if the tape speed at the time of recording was half-speed, if the playback speed is standard speed, to = 1/2 · circle, t = 1/2 · T2, and the playback speed is half-speed. If the feed rate = To, t =
It becomes T2. Therefore, the DC voltage V is V=(t/to)・Eo=(T2/L)・E for any playback speed.
It becomes o. Now, the switch switching circuit 9 is connected to an input voltage V:
(T, /To)・E.

For input voltage V=(T2/To)・Eo, switch the feed speed selector switch 6 to the NP side terminal NP and apply the voltage E to the capstan motor 5. is switched to the SP side terminal SP, and the voltage E2 is applied to the capstan motor 5. Then, as is clear from the above explanation, when the tape recorded at the standard speed starts to be played back, the selector switch 6 is always automatically switched to the NP side terminal NP, and when the tape recorded at the half speed When playback begins, the switch 6 is automatically switched to the SP side terminal SP. In this way, the tape speed is automatically switched to the same speed as when recording. As described above, according to the circuit of this embodiment, automatic adjustment of the tape playback speed can be carried out very easily with a very simple structure. In addition, in the above embodiment, the tape feeding speed was set to the standard speed and a half-speed feeding speed which is 1/2 of the standard speed, but the present invention is not limited to this case, but can be applied to any two feeding speeds. be.

This is because the polarity-reversing control signal for recording on magnetic tape can have a constant repetition period common to all feed speeds and have different duties. . In addition, in the feed speed switching circuit of the embodiment described above, the feed speed is changed by changing the voltage applied to the capstan motor 5 using the feed speed selection switch 6, but the tape feed speed can be changed by other methods, such as a capstan motor. When the motor is an AC synchronous motor, the frequency of the applied AC voltage may be switched. Also, without using the feed speed changeover switch 6, E,;(T,/To)・Eo and E2=
Pulse width T,, T2 so that (T2/T,)・Eo
Alternatively, the output of the low-pass filter 27 may be directly applied to the capstan motor 5 by selecting a voltage value Eo or the like. Also, first and second pulse detection circuits for detecting positive polarity pulses and negative polarity pulses from the signal reproduced by the control head, a control signal reproducing circuit for generating a signal having the same duty as the control signal from the detected pulses, and The smoothing circuit for smoothing the output of the reproducing circuit is not limited to the first and second amplifiers, flip-flops, and low-pass filters in the embodiments described above, but other circuit elements may be used.

Further, the present invention is not limited to the magnetic coin picture reproducing device, but can be easily applied to other recording/reproducing devices such as audio tape recorders.

As described above, according to the recording medium feed speed control device of the present invention, the control signal reproducing circuit generates a signal having the same duty as the control signal recorded on the recording medium, and the recording medium is recorded according to the smoothed DC voltage of the signal. By switching the feeding speed of the medium to the same speed as during recording, there is an effect that automatic switching of the reproduction speed can be performed extremely easily with a very simple configuration.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a magnetic tin picture reproducing device equipped with a recording medium feed speed control device according to an embodiment of the present invention, and FIG. 2a
to f are signal waveform diagrams of various parts of the circuit of FIG. 1. 1...Magnetic tape as a recording medium, 10...
... Control head, 12... Control signal generation circuit, 10... Positive polarity pulse, 1...
Negative polarity pulse, 22... Recording medium feed speed control device, 24, 25... First and second amplifiers as first and second pulse detection circuits, 26...-. Flip-flop as a control signal reproducing circuit, 27...
...Low frequency filter as a smoothing circuit, 29...
Cut-off circuit during feeding. Figure 1 Figure 2

Claims (1)

[Claims] 1. A recording medium that is fed at one of two feed speeds, a control signal generation circuit that generates control signals with the same repetition period and different duties for the two feed speeds during recording, and the control In a recording and reproducing apparatus equipped with a control head for recording a signal on a part of the recording medium, a positive polarity pulse and a negative polarity pulse are respectively detected from a signal reproduced by the control head from a control signal recorded on the previous recording medium. a first and a second pulse detection circuit; a control signal reproducing circuit that takes the outputs of the first and second pulse detection circuits as input and generates a signal having the same duty as the control signal recorded on the recording medium; A smoothing circuit smoothes the output of the signal reproducing circuit, and a feed speed switching circuit that switches the feed speed of the recording medium to one of the two feed speeds according to the output of the smoothing circuit, 1. A recording medium feeding speed control device, characterized in that the feeding speed of the medium is switched to the same speed as during recording.