JPS63195850A - Reproducing system for rotary head type tape recorder - Google Patents

Abstract

PURPOSE:To allow the characteristics of an electromagnetic conversion system or reproducing system such as an equalizer to coincide with that of a reference mode by changing only the rotational frequency of a cylinder to the reference mode at the time of reproducing a tape recorded in an optional mode. CONSTITUTION:A reproduced signal obtained from a rotary head is equalized at its waveform by an equalizer 5, then converted into a digital signal by a zero crossing comparator 6. A logic circuit 7 supplies a sampling pulse SP1 to be a pilot signal to a 1st sampling/holding (SH) circuit 4, a pilot side read signal PR is held by the circuit 4 and a difference between the signals PR, PL is outputted from a subtracter 8. A signal to which an offset voltage from a switching circuit 9 selected by an RF switching signal is applied is outputted from an adder 10 to the 2nd SH circuit 11. At that time, a pulse SP2 is supplied from the circuit 7 to the circuit 11. Thereby, the circuit 11 holds and outputs the output obtained from the adder 10. The output signal is supplied to a capstan motor control part as a tracking error signal to execute tracking control.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Field of Application The present invention is applicable to a tape running speed of 4.7051 ffll, which is one of the recording/playback modes of a rotary head digital audio table recorder (R-DAT). /S, relates to a reproduction method for successfully reproducing a tape recorded at a cylinder rotation speed of 1100 Orp.

(b) Conventional technology Conventionally, R-DAT has a tape running speed of 815Tm/S1.
Apart from the standard recording/playback mode in which digital signals are recorded and played back at a cylinder rotation speed of 2000 rpm, the tape running speed and cylinder rotation speed have been cut in half.
That is, there is an optional recording/reproducing mode in which recording/reproducing is performed at a tape running speed of 4.705111 m/s and a Schilling rotation speed of 11,000 rpm, and recording in this optional mode can double the recording time.

Tracking control of the R-DAT employs an area-divided ATF, and specifically, a tracking area is provided at the trace start and trace end of each track of the tape that is helically scanned by a rotating head. A sync area where a sync signal is recorded and a pilot area where a pilot signal is recorded are provided in each tracking area, and the frequency of the sync signal is distinguished between odd and even tracks, and the area length is also determined. It is a complete 4-track type with two separate tracks. That is, such 4
The track-contained tape pattern is as shown in Figure 4, with four consecutive tracks (t +) (t 2
) (t 3 ) (t +) Tracking regions (Ts) (Te) are formed at the start and end of each trace. And the track (tl) is the tracking area (
Ts), the pilot signal (f'+
) is recorded, and a 1τ sync area where the sync signal (fl) is recorded are provided with an interval of 1, and the sync signal (fl) is recorded in the tracking area (Ie) in order from the starting end of the trace. fl) was recorded 1τ
A sync area of 2τ and a parrot area of 2τ in which the pilot signal (rl) is completely recorded are provided with an interval of 2. The track (t2) also has a sync signal (f3) in the trunking area (Is) in order from the starting end of the trace.
) is recorded, a 2τ pilot area where the pilot signal (fl) is recorded, and a tracking area (
re), the pilot signal (f'
+) is recorded, and seven 0.5τ sync areas are provided with an interval of 1, and a sync signal (f3) is recorded. Furthermore, the track (tJ) has two pilot signals (fl) recorded in the tracking area (Ts) sequentially from the trace starting end side.
A pilot area at τ and a sync area at 0 and 5 where the sync signal (re) is recorded are provided with an interval of 1τ, and the sync signal (fl ) was recorded completely, the sync area of 5τ, and the pilot signal (rl) was recorded 2
Pilot areas of τ are provided with a spacing of 2.5τ. In addition, the track (tJ) is a sync signal (f
3) was recorded in the sink area of 1τ, the pilot rod
Pilot areas of 2τ in which the area signals (fl) are recorded are provided with an interval of 2τ, and in the tracking area (Te), the pilot signals (fl) are recorded sequentially from the trace starting end side.
A pilot area of 2τ in which a signal (fl) is recorded and a sync area of 1τ in which a sync signal (f3) is recorded are provided with an interval of 1.

Then, the sync signal (re) recorded in both the tracking areas (Ts) of tracks (tl) and (tJ) and the sync area of (re>), and the sync signal (re) recorded in the sync area of both tracks (tl) and (tJ) ), the frequency of the sync signal (f3) recorded in the sync area of (Te) is different (
That is, fl is 522.67KHz, f3 is 784
KH2), the frequencies of the pilot signals (fl) recorded in the pilot areas of both tracking areas (Ts) and (Te) of each track (1+) to (1+) are the same (that is, fl is 130.67 KHz>) .

In addition, the diagonal line direction in FIG. 4 shows the difference in head azimuth. Also, the other four consecutive tracks are also track (1
+) to (t4), resulting in the same recording pattern.

And, in such a 4-track complete type, odd number tracks (t
l) (t3) is traced by one rotating head (A head), even tracks (t2) (t4) are traced by the other rotating head (B head), and the head width of A and B heads is It is set slightly larger than the track width. Soshi-01 4 like this!・In the rack-contained type, each of the consecutive 4 tracks (tl) to (t4) is 1
As a cycle, the length and frequency of the sync signal are changed for each head to distinguish the sync signal, and tracking control during playback is performed.

(c) Problems to be solved by the invention However, in the past, even when playing back a tape that has finished recording in the option mode (long-time recording mode), the tape running speed and cylinder rotational speed are the same as in the standard mode. In other words, the signal frequency reproduced by the rotating head becomes lower (in other words, half the signal frequency in the standard mode), and the electromagnetic conversion system such as the head or rotary transformer becomes weaker. This affected the characteristics of the PCM signal equalizer, ATF pilot signal and sync signal extraction, etc. Therefore, when playing in option mode, it is necessary to change the characteristics of the electromagnetic conversion system, equalizer, etc. separately from those in standard mode. If a playback function is provided, complicated circuit processing must be performed to switch the circuit characteristics depending on the mode selection.

(d) Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a tracking area at the start and end of each track of a tape that is helically scanned by a rotary head. A sync area where a sync signal is recorded and a pilot area where a pilot signal is recorded are provided in each tracking area, and the frequency of the sync signal is distinguished between odd and even tracks, and the area length is Mo2
For rotary head tape recorders that perform tracking control during playback using a 4-track complete ATF system that differentiates each track, an optional tape recorder that reduces the tape running speed and cylinder rotation speed to half of the standard recording/playback mode. When playing back a tape on which digital information has been recorded in the recording/playback mode, the tape running speed is not changed and only the number of rotations of 7 cylinders is changed to the standard recording/playback mode. Tracking control is performed using only the tracking area on the tape starting end side and applying different offset amounts to each rotary head.

(E) According to the playback method of the present invention described in Effect E, when playing back a tape recorded in the option mode, only the cylinder rotational speed is changed to the standard mode while the tape running speed remains the same. Therefore, the characteristics of the reproduction system such as the electromagnetic conversion system and equalizer can be made the same as in the standard mode.In other words, the standard mode can be used as is, and the burden on the reproduction system is significantly reduced. .

(f) Examples An embodiment of the present invention will be described below with reference to the drawings.

That is, according to the playback method of the present invention, when playing back a completely recorded tape in option mode, the tape running speed is 4.
．． This is done by changing only the cylinder rotation speed to the standard mode of 2000 rpm while maintaining 705ml/S, so the signal frequency reproduced by the rotating head becomes the same signal frequency as the standard mode, and the electromagnetic conversion system It is possible to operate reproduction systems such as , equalizer, ATF, etc. with the same characteristics as in standard mode.

Here, if the rotation speed of the cylinder is set to 200 rpm when playing back a tape recorded in option mode, the lead angle of the rotating head during playback is different from the track angle during recording, so the trace starting end of each track on the tape With the two-point ATF method, which performs tracking control based on the sink signal and pilot signal of both tracking areas formed at the trace end and the trace end, there is a risk that tracking will not be achieved forever. By adopting a two-track complete type one-point ATF, type b, which performs tracking control using only the rotary head, and by giving a different offset amount to each rotary head, the same tracking performance as before can be obtained.

Specifically, the tracking control circuit has a configuration as shown in Figure 1, and uses two rotating heads (heads A and B) whose head width is wider than the track pitch to control the tape as shown in Figure 4. When playing back a tape on which a pattern has been recorded, for example, when the starting end of track (1+) is played back and traced by one rotating head (A head), the output of this rotating head is amplified by the playback amplifier (1). It is supplied to LPF (2) which extracts the rear pilot signal.

The pilot signal components obtained from this LPF(2) are the pilot signal PM from the home track to be traced and the pilot rod side read signal P* from the adjacent left and right tracks, that is, the right track, as shown in FIG. and,
Pyro side read signal P1 from left track.
It consists of. As shown in Part B, the pilot signal component extracted by the LPF (2) is passed through the envelope detector (
After being subjected to envelope detection by step 3), the signal is supplied to the first sample and hold circuit (4). On the other hand, the reproduced signal from the rotary head is waveform-equalized by an ifsizer (5) and then converted into a digital signal by a zero-cross comparator (6). And logic circuit (7)
digitally processes this signal and simultaneously detects the sync signal and generates the first sampling pulse SP+ for sampling the pilot signal at the timing shown in Figure 2.
Supplied to the sample hold circuit (4). Therefore, the first
In the sample hold circuit (4), the pilot rod side read signal P is held by this sampling pulse SP+, and the pilot rod side read signals P and P are held.

The difference is output from the subtractor (8). Then, the output obtained by adding the offset voltage from the switch circuit (9) selected by the RF switching signal to the output from the subtracter (8) is supplied from the adder (10) to the second sample and hold circuit (11). be done. At this time, the logic circuit (7
) is supplied to the second sample and hold circuit (11).

Therefore, by this sampling pulse SP2, the second
The output from the adder (10) is bolded and output in the blank hold circuit (11). This output signal is supplied as a trunking error signal to the capstan morph control section, and tape running control is performed so that the tracking control signal becomes zero.

In addition, the amount of offset given to \rad is shown in Figure 3 (a).
As shown in the figure, the A head is 145 degrees, the B head is +45 degrees,
Or +45 degrees to the A head as shown in Figure 3 (b).
The B head may be tilted at either -45 degrees, with a tape running speed of 4.7Q5mm/S and a cylinder rotation speed of 11.
If a tape recorded at 00 Orp is played back by increasing the cylinder rotation speed to 2000 rpm while keeping the tape running speed unchanged, the same track on the tape will be traced with both heads A and B shifted to the left and right. This is given to correct misalignment and achieve an optimal on-track condition. That is, in the case of Figure 3(a), ■ and ■ are A.
The head traces ■ and ■ become the B head traces, and the A head trace ■ is used to play the A track.
The B head trace ■ will be used to play back the B track, and in the case of Figure 3 (b), ■ and ■ will be the A head traces, ■ and ■ will be the B head traces, and the A track will be played back. The trace ■ of the A head is used for the reproduction of the B track, and the trace ■ of the B head is used for the reproduction of the B track. Therefore, in the former case, the switch circuit (9) is switched to the contact (a) side so that the offset voltage applied to the adder (10) is a negative DC voltage so that an offset amount of 145 degrees is applied to the A head. But, +45 to B head again.
Switch circuit (9) so that the offset amount of degrees is given.
is switched to the contact (b) side, and a positive DC voltage is applied to each contact. Note that by tracing the same track, output can be obtained from both heads A and B, but the output from the head that matches the azimuth of the recording track (that is, the one with the larger output) is taken out and sent to the playback system. Send. Therefore, also in sync detection, a sync signal that matches the azimuth of the head is selected and used, making it possible to prevent tracking disturbances due to erroneous sync detection.

In addition, although a 4-track complete tape pattern is used in this embodiment, tracking control is performed using a 2-track complete tape pattern, as shown in FIG. This is to prevent tracking malfunctions caused by tracing. In other words, if it is a 4-track complete type, 1 rotation per 2 revolutions of the cylinder.
Tracing 4 tracks as a period (i.e., in Figure 4, trace the track (1+n (t2) with the first A and B heads, and trace the tracks (t3) (t4) with the second A and B heads). However, in this embodiment, it is not possible to trace track (t +) (t 2) L in two revolutions of the cylinder, so in the second B head, the sync signal at 1 on 1 - rack (t4) is For example, in the case of FIG. 3(a), 0.0 on the track (t2) should be detected.
This is because a sync signal of 5τ is detected, resulting in a steady tracking error.

(G) Effects of the Invention As described above, according to the present invention, when playing back a tape recorded in the optional mode in which the tape running speed and cylinder rotation speed are reduced to half of the standard mode, the tape running speed remains unchanged. Since only the cylinder rotation speed is changed to the standard mode, the characteristics of the Tr, magnetic conversion system, ifraiser, etc., can be made the same as in the standard mode. It can be used as is, so if you want to play back a tape recorded in option mode on a standard mode R-DAT, simply cut the tape running speed in half without changing the characteristics of the playback system. You can do it easily. In addition, tracking control at this time uses only the tracking area on the trace start side and does not give different offset amounts to each rotating head, so it is performed in a two-track complete type, so it operates in the same way as normal playback. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the tracking control circuit section of the present invention, FIG. 2 is its timing chart, and FIG. 3 (a
) and (b) are diagrams showing head tracing, and FIG. 4 is a diagram of a tape pattern for tracking control. (t +) (t a) (t 3) (t J... track, (Is) (Te) - tracking area, (4) (1
1)...First and second sample and hold circuits.

Claims (1)

[Claims] (1) A tracking area is formed at the trace start end and trace end of each track of the tape that is helically scanned by a rotating head, and a sync area in which a sync signal is recorded in each tracking area and a pilot signal are recorded in each tracking area. Tracking during playback is achieved using a 4-track complete ATF method that separates the frequency of this sync signal into odd and even tracks and also distinguishes the area length every two tracks. When playing back a tape on which digital information has been recorded in an optional recording/playback mode in which the tape running speed and cylinder rotation speed are reduced to half of the standard recording/playback mode in a rotary head type tape recorder that performs control, Playback is performed by changing only the cylinder rotation speed to the standard recording/playback mode without changing the tape running speed,
A playback method for a rotary head type tape recorder, characterized in that tracking control during playback is performed using only the tracking area on the tape starting end side and while giving different offset amounts to each rotary head.