JPH01292607A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To reduce the cost of a drum, and to improve productivity by attaching a head consisting of two gaps of double-azimuth to a rotary drum, and generating a head switching signal to invert itself at every one revolution of the rotary drum. CONSTITUTION:The rotary drum 4 is provided with one head consisting of two gaps of the double-azimuth. A PG sensor 27 installed in the vicinity of the rotary drum 4 detects the revolution of the rotary drum, and the head switching signal HSW1 inverting itself alternately into H-level and L-level is sent from a HSW shaping circuit 28 at every one revolution of the rotary drum to a servo circuit 21 and a duty adjustment circuit 29. The duty adjustment circuit 29 adjusts the head switching signal HSW1 so as to correspond to a time difference between two gaps of the head. The adjusted head switching signal HSW2 is sent to the servo circuit 21 and an RF amplifier 24, and the timing of recording and reproducing for the head is controlled. By using one head drum of the double-azimuth, the cost of the drum can be reduced, and in addition, the productivity can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus using a double azimuth one-head drum.

[Prior art and problems to be solved] Conventionally, magnetic recording/reproducing devices such as head rotating DAT
(Digital audio φ tape recorder) generally uses a two-head drum. However, in the case of this two-head drum system, multiple heads are attached to the rotating drum, so bearing adjustment between the heads is required.
It is necessary to make many adjustments, such as adjusting the height of the head and adjusting the mechanical parts accordingly, resulting in problems such as an increase in the cost of the rotating drum and a decrease in productivity.

The present invention has been made in view of the above circumstances, and by using a double azimuth single-head drum, the cost of the drum can be reduced and productivity can be improved.
An object of the present invention is to provide a magnetic recording/reproducing device that can obtain performance equivalent to that of a head drum.

[Means and effects for solving the problems] The present invention provides a rotating head type magnetic recording/reproducing device in which a head consisting of two double azimuth gaps is attached to a rotating drum, and each time the rotating drum rotates once, In addition to generating an inverted head switching signal, the duty of this head switching signal is adjusted in accordance with the time difference between the two gaps of the heads, and recording/reproduction is performed for the heads based on this adjusted head switching signal. It is designed to perform timing control.

By adjusting the duty of the head switching signal as described above, even if a double azimuth head is used, each track can be recorded/reproduced from the correct position.

The present invention also provides a rotating head type digital audio system.
In a tape recorder, a rotating drum is provided with one head consisting of two gaps of double azimuth, and this rotating drum is rotated at twice the normal speed, and when the magnetic tape is running, the magnetic tape and the magnetic head are The feature is that the lead angle when the tape is stopped is set in advance to a large value so that the lead angle (track angle) with the tape matches a standard value.

As mentioned above, in a digital audio tape recorder, by setting the lead angle between the magnetic tape and the magnetic head to a large value in advance when the tape is stopped, the lead angle and the track length on the magnetic tape when the tape is running are standardized. Can be matched to a value.

[Embodiments of the Invention] Hereinafter, an example in which the present invention is implemented in a DAT will be described in detail with reference to the drawings. First, the schematic structure of the mechanical parts will be explained with reference to FIG. In the figure, l is a DAT tape cassette, which is shown installed in the apparatus. When this cassette 1 is installed in a magnetic recording/reproducing device, the magnetic tape 2 is moved between guide rollers 3a, 3.
b and guided to the rotating drum 4 section. In the vicinity of this rotating drum 4, inclined pins 5a and 5b are provided, and as shown in FIG. . The rotating drum 4 is provided with one double azimuth head 6, the details of which will be described later.

As mentioned above, since the rotating drum 4 is provided with one double azimuth head 6, its rotational speed fV is set to a value twice (4000 rpm) compared to the case of a two-head drum (200 Or p m ). After passing through the rotating drum 4 section, the magnetic tape 2 is guided to the capstan 9 and idler 10 sections via guide rollers 7.8. The magnetic tape 2 is driven to run at a constant speed by the capstan 9 and the idler IO, and is further returned into the cassette 1 via the guide roller 11.

= 5- double azimuth head 6 provided on the rotating drum 4
As shown in FIG. 3(a), the core 12 is approximately E-shaped.
Coils Lea to 13c are wound around the coils, and gaps A and B are formed in front of the coils Lea to 13c.

These gaps A and B are at the azimuth angle specified in the standard, for example, ±20' with respect to the center line, as shown in Fig. 3(b).
An azimuth angle θA2 of is set.

By using the above double azimuth head 6 and alternately switching the gaps A and B, a recording track 2a with the gap A is formed on the magnetic tape 2 as shown in FIG.
Recording tracks 2b are formed alternately by the gap B and the gap B. Recording tracks 2a and 2b have different azimuth directions, and as a result, recording tracks 2a and 2b have different azimuth directions.
Crosstalk between a and 2 b is prevented.

However, as mentioned above, one double azimuth head 6
is attached to the rotating drum 4, its rotational speed fv is 2
It is necessary to set the lead angle to twice that of the head drum, but if the rotational speed is doubled and the same value as before is used as the lead angle when the tape is stopped, the actual track length will be D.
The length is longer than the AT format standard.

Hereinafter, the relationship between the lead angle and the track length when the tape is running and when the tape is stopped will be explained with reference to FIG. Note that the lead angle shown in FIG. 5 is a value when a rotary drum 4 having a common diameter φ of 30 mm is used.

■ in Figure 5 indicates the trajectory of the head during tape running in the DAT format, and its lead angle θ is 6°22'
It is 59.5'. ■ indicates the trajectory of the head when the tape stops in the DAT format, and its lead angle θ
0 is 6°22'. Further, in FIG. 5, Fv is the rotational speed (200 rpm) of the rotating drum 4, and Vt is the relative speed between the magnetic tape 2 and the magnetic head 6. Then, when the rotary drum 4 is rotated at twice the speed (4000 rpm) of the 2-head case with the lead angle when the tape is stopped set to 6°22', the same value as the DAT format, the head when the tape is running is The trajectory of is as shown in ■■
The track length 0 becomes longer than the format standard. This is also clear from the sum of the vector quantities shown by arrows in FIG. 5, that is, the vector sum of the rotational speed Fv of the rotary drum 4 and the relative tape velocity Vt. Therefore, in this embodiment,
As shown in the figure, the value of the lead angle θl when the tape is stopped is set to 6°22'29.0', which is larger than that in case ①, so that the track angle and track length when the tape is running match the format standard. There is.

Here, the standard of the DAT format will be explained with reference to FIG. 5 above. The DAT format standard is
As shown below, effective recording width W: 2.613 mm Tape speed Vt: 8.150 mm/s Track length: 23.501 mm (during tape running) Lead angle θ. , θ When the tape is stopped (θo): 6°22' When the tape is running (θ): 6°22'59.5'.

In this embodiment, the tape format is set as follows in order to conform to the above standards with one head drum.

Track length il: 23.534 mm (when the tape is stopped) Lead angle θ1: 6° 29'29.0' (when the tape is stopped) Drum rotation speed Fv: 4000 rpm In Fig. 5 above, d indicates that the head is in the tape area. This is the length the tape moves between entering and exiting.

Therefore, the relationship between the lead angle θ and θ1 and the relationship between the track length and 11 can be determined by the following formula.

That is, from Fig. 5, #2=d2+g+' -2・d -47,・cosθ1
The relational expression can be found. In the above equation, W is the width of the magnetic tape 2, and φ is the diameter of the rotating drum 4.

N is a variable.

Next, a variable N that is inversely proportional to the wrap angle is determined using the above equation. In this case, Vt/Fv -8°W/sinθ-ri,
Letting π·φ−Z, the formula for the solution can be obtained. The variable N is determined by this formula, and the lead angle θl when the tape is stopped is
(6″29′29.0′) and track length 11 (2
3,534-10=mm) can be determined.

Next, a system configuration for controlling the above magnetic recording/reproducing mechanism will be explained. FIG. 7 is a block diagram showing the entire system. In the figure, 21 is a servo circuit, and the CPU 22
The motor 23 is driven and controlled based on instructions from the controller, and the rotary drum 4 is rotated at 400 rpm. The above rotating drum 4
A magnetic head for recording/reproducing provided in is connected to an RF amplifier 24 via a rotary transformer or the like.

The RF amplifier 24 provides reproduced data read from the magnetic head to the digital signal processing circuit 25, or inputs recorded data provided from the digital signal processing circuit 25 to the magnetic head. Further, the RF amplifier 24 outputs a part of the reproduced signal read from the magnetic head to an ATF (automatic tracking) circuit 26.

Further, the ATF circuit 26 is given an operation timing signal from the digital signal processing circuit 25.

The ATF circuit 2B samples the reproduction signal based on the timing signal from the digital signal processing circuit 25, determines whether the head is correctly tracing the recording track, and sends a correction signal to the servo circuit 2 according to the determination result.
Output to 1.

On the other hand, a PG sensor 27 is provided near the rotating drum 4. This PG sensor 27 is
This sensor detects the state and generates one pulse each time it rotates, and the output pulse is sent to the H8W (head switching signal) shaping circuit 28.

This HSW shaping circuit 28 outputs a head switching signal H8WI whose high level and low level are alternately inverted every time a pulse signal is input from the PG sensor 27. The signal is sent to the adjustment circuit 29.

The duty adjustment circuit 29 is a circuit that corrects the head switching signal H8WI in response to the time difference between the gaps A and B of the double azimuth head 6, as will be described in detail later. circuit 21
and sent to the RF amplifier 24. The servo circuit 21 outputs the head switching signal H8WI to the ATF circuit 26, and outputs the head switching signal H8W2 to the digital signal processing circuit 26.
Output to 5.

-12= The digital signal processing circuit 25 and the RF amplifier 24 determine the read/write timing based on the head switching signal H8W2.

The digital signal processing circuit 25 includes a CPU 22°R.
It is connected to an AM 31 and a data bus 32, and further connected to this data bus 32 are a RAM 31 and an error correction/AD/DA interface 33. This error correction/A
A recording audio signal is input to the D-DA interface 33 via a low-pass filter 34 and an A/D conversion circuit 35. Further, the error correction/AD-DA interface 33 converts the reproduced data into the D/A conversion circuit 3B.
and output via a low-pass filter 37.

Next, details of the duty adjustment circuit 29 will be explained with reference to FIG. The duty adjustment circuit 29 includes a low-pass filter 41 and a Schmitt trigger circuit 42. The low-pass filter 41 includes, for example, a resistor R and a capacitor C, and a diode D is connected to the resistor R in parallel. In this case, diode D is connected such that its cathode is on the signal input side.

In the above configuration, from the H8W signal shaping circuit 28 to the ninth
When the head switching signal H8WI shown in FIG. A is input to the low-pass filter 41, the diode D is turned on at the falling edge of the signal, and the low-pass filter 41 does not act. Therefore, when the head switching signal H3WI falls, it passes through the low-pass filter 41 as is, as shown in FIG. 9B, and is output from the Schmitt trigger circuit 42 without delay, as shown in FIG. 9C. However, when the head switching signal H8WI rises, the diode D
is turned off, and the low-pass filter 41 comes into operation. Therefore, the high frequency component of the head switching signal H8WI is cut by the low pass filter 41, and the output signal has an integrated waveform as shown in FIG. 9B. The output signal of this low-pass filter 41 is waveform-shaped in a Schmitt trigger circuit 42 as shown in FIG. 9C. Therefore, the head switching signal H8W2 output from the Schmitt trigger circuit 42 has a rising edge at a predetermined time. This delay time is set in accordance with the time interval between gaps A and B of the double azimuth head 6, that is, the time it takes for gap B to reach the position of gap A due to head rotation. In the example, it is 63 μsec.

FIG. 10 shows the timing of the head switching signal H8W and recording/reproduction by the head. Conventionally ■,
As shown in ■, the head A is switched on by the head switching signal H8WI.
and head B are switched to record/reproduce signals. On the other hand, in this embodiment, the gap A and the gap B of the double azimuth head 6 are switched by the head switching signal H8W2 as shown in (1) and (2) to record/reproduce signals. In this case, as described above, the timing of the rise of the head switching signal H3W2 to the high level is delayed by a predetermined period of time to match the timing with the track formed on the tape.

That is, as shown in FIG. 11(a), for the gap A of the head 6, there is a (
Recording is started from position A), but if the normal head switching signal H3WI is used at this time, recording will start before gap B reaches the normal position, as shown in FIG. Therefore, a track pattern compatible with the DAT format cannot be obtained. However, by using the head switching signal H3W2 whose duty has been adjusted as described above, the timing at which gap B starts recording can be delayed to match the normal position, as shown in FIG. 11(C). A track pattern compatible with the DAT format can be obtained. Furthermore, during reproduction, the reproduction operation can be started from accurate positions for both gaps A and Gap B in the same manner as during recording.

As described above, recording/reproduction compatible with the DAT format can be performed even when a double azimuth one-head drum is used, and compatibility with a DAT using a two-head drum can be maintained.

In the above embodiment, the case where the present invention is applied to a DAT is shown, but the present invention can also be applied to a VTR in the same manner as in the case of a DAT.

[Effects of the Invention] As detailed above, according to the present invention, since a double azimuth one-head drum is used, processes such as bearing adjustment and step adjustment, which account for a large proportion of the cost of the drum, can be omitted. This makes it possible to significantly reduce costs and reduce mechanical adjustments.

Further, since the duty of the head switching signal H8W is adjusted to correct the time difference between the head gap A and the gap B, recording/reproduction that conforms to the specified format can be performed.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 shows a schematic structure of a mechanical system, FIG. 2 shows a wrap angle of a tape with respect to a drum, and FIGS. 3(a) and (b). 4 is a perspective view and a front view of the head portion, FIG. 4 is a diagram showing the track pattern formed on the tape, FIG. 5 is a diagram for explaining the tape format, and FIG. 6 is a diagram showing the lead angle of the head with respect to the tape. 7 is a block diagram showing the configuration of the entire system, FIG. 8 is a diagram showing the configuration of the duty adjustment circuit, FIG. 9 is a signal waveform diagram for explaining the operation of the duty adjustment circuit, and FIG. 11 is a diagram for explaining recording/reproducing timing, and FIGS. 11(a) to 11(C) are diagrams showing the relationship between the track pattern and the recording/reproducing start position of the head. ■...Cassette, 2...Magnetic tape, 3 a, 3
b. 7.8.11... Guide roller, 4... Rotating drum, 5 a, 5 b... Inclined pin, 9... Capstan, lO... Idler, 21... Servo circuit, 2
2...CPU. 23...Motor, 24...RF amplifier, 25...
Digital signal processing circuit, 26...ATF circuit, 27.
...PG sensor, 28...H8W signal shaping circuit, 29
...Duty adjustment circuit, 41...Low pass filter, 42...Schmitt trigger circuit. Figure 2 (B) Figure 2 (B) Fig. 3 Takeshi Suzue, Agency Takeshi Suzue, Fig. 3

Claims (2)

[Claims] (1) A rotating head type magnetic recording and reproducing device includes a rotating drum equipped with a head consisting of two gaps of double azimuth, and a motor that rotationally drives the rotating drum.
Head switching signal generating means detects the rotation of the rotating drum and generates a head switching signal that is inverted every time it rotates, and the duty of the head switching signal output from this means is determined by the time difference between the two gaps of the heads. A magnetic recording/reproducing device comprising: a duty adjustment circuit that adjusts the duty according to the duty adjustment circuit; and a control means that controls recording/reproduction timing for the head based on a head switching signal adjusted by the duty adjustment circuit. Device. (2) In a digital audio tape recorder, a rotating drum equipped with one head consisting of two gaps of double azimuth, a driving means for rotating this rotating drum at twice the normal speed, and a magnetic tape running 1. A magnetic recording and reproducing apparatus comprising means for presetting a lead angle at a time when the tape is stopped to a large value so that the lead angle between the magnetic tape and the magnetic head matches a standard value.