JPH02139748A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To expand the limit of search speed and to make a search at high speed by providing a double speed reproducing function, using a double speed reproducing mode and performing the high speed search. CONSTITUTION:Operation speed of a signal processing circuit 9 for double speed reproducing is set as two times faster than a signal processing part 8 for normal producing. That is, a signal band of an equalizer amplifier 22 is about two times wider than an equalizer amplifier 19, and the operation characteristics of a data strobing circuit 23 is also two times as much as a data strobing circuit 20, and then a signal processing circuit 24 is also constitutive of operating two times faster than a signal processing circuit 21 by raising a master clock frequency of the circuit 24. When a cylinder is at 4,000r.p.m. as two times as much as its normal reproducing case while a tape is also at 16.3mm/s under the double speed reproducing as two times faster than the normal reproducing, two times clock and data are reproduced by a transmission rate. By this method, the high speed search can be made under the double speed reproducing mode.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotary head type digital audio tape recorder (hereinafter referred to as DAT), and is particularly suitable for speeding up random access such as music selection. The present invention relates to a magnetic recording/reproducing device.

[Conventional technology]

In order to perform high-speed random song selection (searching for the beginning of a song) at a speed several tens to hundreds of times faster than the normal playback speed in a rotating head type DAT, it is necessary to use a signal and time indicating the start of a song recorded in a track. Control signals such as display signals and track number information signals that are recorded at the same recording density as music PCM signals must be accurately read when the tape is running at high speed.

By the way, when a tape is run at a high speed different from that during normal recording and playback, the head's running trajectory will cross multiple signal tracks recorded on the tape, and assuming the cylinder rotation speed is constant, the head and tape The relative speed will change.

On the other hand, in DAT, a data punching (data strobe) circuit is used as a circuit to reproduce a digital signal from the signal reproduced from the head, but the input transmission rate of this circuit is usually set to have a margin for speed deviation and jitter in the tape running system. is around ±104%, and as the tape runs at high speed, the relative speed with the head changes, and if the input signal transmission rate deviates from the range of around ±10%, data cannot be reproduced, in other words, random access is not possible. happen.

For this reason, with DAT, when the tape is running at high speed, the cylinder rotation speed cannot be the same as during normal recording and playback, so the relative speed between the head and tape must be kept constant or within the permissible jitter of the data strobe circuit. like,
It is essential to control it according to the running speed of the tape.

The relationship between the tape running speed and the cylinder rotation speed for keeping the relative speed between the tape and the head constant will be described below.

FIG. 8 is a diagram showing the scanning of the head during normal recording and reproduction, in which 1 is the head, 2 is the tape, and 3 is the signal track on the tape.

The relative speed V between the tape and head at this time. is expressed by equation (1).

Vo"(vHoaJsθ-Vr)" + (Vy□t
mθ)'' -o) Here, VHO is the rotational speed of the head or cylinder during normal recording and reproducing, θ is the inclination angle of the track, and vr is the tape running speed during normal recording and reproducing.

On the other hand, when the tape is run at n times the speed of normal recording and playback, the relative velocity V is expressed by equation (2) when the tape is run in the FF (fast forward) direction, and when the tape is run in the REV (rewind) direction. In this case, each is expressed by equation (3).

FIG. 9 shows the relationship when the relative velocity V in equations (2) and (3) is assumed to be equal to the relative velocity v0 during normal recording and reproduction in equation 11).

In FIG. 9, in order to maintain the same relative speed as during normal recording and playback, if the tape is run at a high speed of 200 times, the cylinder rotation speed must be increased to 300 or more in the FF direction.
It is necessary to control the speed at 11000 rpm in the nFXw direction.

The cylinder rotation speed is changed according to the tape running speed,
An example of a device for controlling the relative speed between the tape and the head is the one described in Japanese Patent Laid-Open No. 61-214164.

These devices control the cylinder rotation speed in a data strobe circuit so that the reproduced clock frequency obtained as a frequency synchronized with a reproduced signal becomes a predetermined fixed frequency.

In addition, related to this type of device, as a conventional technique for controlling tape running at a constant high speed, for example, Japanese Patent Application Laid-Open No. 57-12448
Examples include those described in Japanese Patent Application Laid-open No. 136306/1983.

[Problem to be solved by the invention]

In the above conventional technology, as is clear from FIG.
In the RBW direction, the tape running speed must be high (as the cylinder rotation speed must be lowered accordingly, for example, 40
If an attempt is made to search for 0 times, the cylinder rotational speed will stop, which is impossible. In other words, the search in the conventional technology has a limit of about 250 times, although it also depends on the data reproducing ability of the signal processing circuit.

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic recording and reproducing apparatus equipped with a search system that can improve the search speed by twice as much as the conventional one.

[Means to solve the problem]

The above object is achieved by providing a playback device with a double-speed playback function and performing a high-speed search in the double-speed playback mode.

In other words, in the double-speed mode in which both the tape running speed and the cylinder rotational speed are twice that of normal recording and playback, the playback signal frequency is only doubled, and the head running trajectory is the same as that during normal recording and playback shown in Figure 8. Therefore, the search speed limit based on double speed mode is relatively the same as the conventional normal mode, but in terms of absolute tape speed, the relative cylinder rotation speed when searching in normal recording/playback mode is 2
Since the height can be doubled, high-speed searches in the REW direction can be performed as shown in FIG. 9.

Note that if you use the double speed playback mode to speed up the search, the reference value of the cylinder rotation speed will be 200Or in the normal mode.
pm, which is as high as 4000 rpm, and as can be seen from the characteristics in Figure 9, the cylinder rotation speed in the FF direction reaches a very high range, resulting in disadvantages such as increased noise. In the FF direction, the cylinder rotational speed is controlled to be increased in accordance with the speeding up of the search, so the problem can be solved by performing the search in the normal recording/reproducing mode, without particularly using the double speed mode.

[Effect]

The double speed playback function is a function of playing back a signal with twice the transmission rate when the tape speed and the cylinder rotation speed are both twice that of normal recording and playback.

The tape high speed running control means is, for example, disclosed in the above-mentioned Japanese Patent Application Laid-open No. 54
- Publication No. 136306 ζ The rotational speed of the reel shaft on the winding side is adjusted according to the tape running direction so that the sum of the rotational speeds of both the reel stands on the tape supply side and the winding side is constant as described in this publication. and is configured to control the tape to run at high speed.

Further, the cylinder rotation speed control means detects the reproduced clock frequency of the data strobe circuit as described in, for example, the above-mentioned Japanese Patent Laid-Open No. 61-214164, and this frequency is always constant with respect to the tape speed. like,
That is, the cylinder rotation speed is controlled so that the relative speed between the tape and the head is constant.

With the above configuration, if the signal reproduction during high-speed search is performed using the double-speed reproduction function, the cylinder rotational speed will be twice as much as the reproduction signal from the head in the normal recording and reproduction mode, relative to the tape running speed. That is, the transmission rate is controlled to double. Therefore, if we take the tape speed during double-speed playback as a standard, the search speed limit is the same as shown in Figure 9 because the cylinder rotational speed is doubled for the search double-speed ratio, but the tape speed during normal recording and playback is With an absolute speed ratio based on speed, it is possible to realize a high-speed search equivalent to twice that of normal recording and reproduction.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a magnetic recording and reproducing apparatus according to the present invention, in which 1a and 1b are a pair of rotating magnetic heads having mutually different azimuth angles, 2 is a magnetic tape,
4 is a cylinder, 5 is a tape supply side reel stand, 6 is a tape take-up side reel stand, and 7 is a tape high speed running control means, which includes a tape supply side reel fG12 and a tape take-up side reel f.
G13, f-■ converters 14, 15, adder 16, drive circuit 17, and reel motor 1 that drives the reel stand 5.6.
Consists of 8.

8 is a signal reproducing circuit for normal reproduction;
, a signal reproducing equalizer amplifier 19 that amplifies the reproduced signals of lb, a data strobe circuit 20, and a signal processing circuit 21.
It consists of

Reference numeral 9 denotes a signal reproducing circuit for double-speed reproduction, which is composed of a signal reproducing equalizer amplifier 22, a data strobe circuit, and a signal processing circuit 24.

Reference numeral 10 denotes cylinder rotational speed control means during high-speed search, which is comprised of an f-V converter 5 which inputs the recovered clock frequency of okara and a drive circuit 26, and drives the cylinder motor 11.

In the figure, the signal reproducing equalizer amplifier 19 in the signal reproducing circuit 8 for normal reproduction has a head of 1 m.

Specifically, two equalizer amplifiers are provided corresponding to heads 1m and 1b to amplify the playback output from 1b, and each head is in proper contact with the tape 2 in synchronization with the rotation of the cylinder 4. Switching control is performed to select these reproduction outputs during the period, but in FIG. 1, one equalizer amplifier 19 is omitted.

The data strobe circuit 20 reproduces digital data and clocks from the output of the equalizer amplifier 19.

FIG. 2 is a block diagram of the data strobe circuit 20 of FIG. 1, in which 27 is a binarization circuit, 29 is a loop filter for phase comparison, 30 is a voltage controlled oscillator, and 31 is a latch circuit.

In the figure, a phase comparator, a loop filter 29, and a voltage-controlled oscillator 30 constitute a PLL circuit, and feedback control via the phase comparator circuit and the loop filter 29 allows the frequency and phase of the voltage-controlled oscillator 30 to be changed to 2. It operates to match the frequency and phase of the signal fl from the value conversion circuit 27, and regenerates the clock.

Further, the latch circuit 31 latches the binarized data in synchronization with the reproduced clock.
1, digital data synchronized with a clock is reproduced.

FIG. 3 is a diagram showing the input/output characteristics of the PLL circuit shown in FIG. It indicates a lock range, and if fi deviates from this range, the lock will be lost and data and clock reproduction will be impossible.

Normally, this lock range is the center value fl of the input signal.

(DAT: 4.704 MHz in normal playback mode) is around ±101.

Returning to FIG. 1, the signal processing circuit 21 performs various processes such as data error correction based on the clock and data reproduced by the data strobe circuit 4, and reproduces digital data.

The configuration and operation of the signal reproducing circuit 8 for normal reproduction have been explained above, but of course, this circuit rotates the cylinder at a constant speed of 2000 rpm.
This is a playback circuit that corresponds to the case where the tape is also run at a constant speed of 8.15 sn/s.

Note that the constant speed rotation control of the cylinder and the capstan control for running the tape at a constant speed are not directly related to the structure of the present invention, and therefore their explanation will be omitted.

The configuration and operation of the signal processing circuit 9 for double-speed playback are similar to those of the signal processing circuit 8 for normal playback, but the operating speed of each structure is set to twice that of the signal playback circuit 8 for normal playback. There is.

That is, the signal band of the equalizer amplifier 22 is approximately twice as wide as that of the equalizer amplifier 19, and the signal band of the equalizer amplifier 22 is approximately twice as wide as that of the equalizer amplifier 19.
As shown in Figure 4, the operating characteristics of the signal processing circuit 2 have been doubled compared to those of the data strobe circuit, and the signal regeneration circuit has also been improved by increasing the master clock frequency of the circuit.
It is configured to operate at twice the speed compared to 1, and the cylinder operates at 400 Orpm, which is twice the speed during normal regeneration.
, and the tape output is 16.3W/2, which is twice that during normal playback.
It operates to reproduce the clock and data at twice the transmission rate during reproduction at double the speed of s.

The tape high speed running control means 7 is, for example, disclosed in Japanese Patent Application Laid-Open No. 54-13
The r-v converters 14 and 15 are equivalent to those described in Japanese Patent No. 6306. The r-v converters 14 and 15 are composed of, for example, a monostable multivibrator and an integrating circuit, and are connected to the tape supply side reel stand 5 and the tape winding side, respectively. The frequency signals of the reel fG signals 12 and 13 obtained in synchronization with the rotation of the take-side reel stand 6 are converted into voltage.

The adder 16 is constituted by, for example, an adding circuit using resistors, and adds the output signals of the fV converters 14 and 15.

The drive circuit 17 is composed of a comparator and an amplifier that compare a predetermined reference voltage and the output signal of the adder 16, and the reel stand 5, The rotation of the reel motor 18 that drives the reel motor 6 is controlled.

With the above configuration, the output of the adder 16 matches the setting of the reference voltage of the drive circuit 17, that is, the sum of the rotation speeds of the tape winding side and supply side reel stands becomes equal to the reference voltage. Since the rotation of the reel motor 18 is controlled in this manner, the tape is run at an arbitrary speed according to the setting of the reference voltage.

The cylinder rotation control means 10 is, for example, JP-A-61-21
The f-V converter 5 may be the same as that described in Japanese Patent No. 4164, and converts the clock frequency reproduced from the data strobe circuit n of the signal reproduction circuit 9 for double-speed reproduction into a voltage.

The drive circuit 26 includes a comparator, an amplifier, etc. that compares a predetermined reference voltage with the output signal from the fV converter 25, and ensures that the comparison error between the reference voltage and the output of the fV converter 25 is zero. The rotational speed of the cylinder motor 11, that is, the cylinder 4 is controlled so that the speed at which the feed throat 1j1°1b scans the signal track on the tape 2 is controlled.

With the above configuration, the above-described tape high-speed running control means 7
When the tape is running at high speed, the cylinder rotational speed is set so that the reproduction clock frequency of the data strobe circuit remains constant, that is, the relative speed between the head and the tape remains constant (transmission rate constant). controlled by.

The above is an explanation of the configuration and operation of each part in Figure 1. In high-speed search control, the signal played back from the head is twice as much as normal playback with respect to the tape running speed. The rotational speed of the cylinder is controlled so that the speed is twice that of normal regeneration.

As a result, based on the tape speed during double-speed playback,
Although the search speed limit is relatively the same compared to a search using normal playback mode, comparing in absolute tape speed is twice as fast as a search using normal playback mode. This can be easily inferred from equations (1) to (31) described above.

FIG. 5 is a diagram showing the relationship between cylinder rotational speed control and tape running speed when the relative speed between the head and tape is constant according to the embodiment of FIG. 1, and when using the conventional normal playback mode. was the characteristic (1) indicated by the broken line,
By using the double speed playback mode to increase the reference values of the cylinder rotation speed and tape speed, and performing signal playback at twice the transmission rate, the solid line characteristic (II) can be obtained, and the search speed limit is doubled. can be expanded to.

By the way, as can be seen from the characteristics shown in Fig. 5, if you try to control searches in the FF direction and RFfW direction in common using the double speed playback mode, the control range of the cylinder rotation speed becomes wider.For example, 400 times faster search In order to perform this, it is necessary to change the cylinder rotation speed from 2000 to 6000 rpm, and the cylinder rotation speed control means 1 shown in FIG.
This has the disadvantage that not only a wide dynamic range is required for zero, but also the noise of cylinder rotation increases.

FIG. 6 is a configuration diagram showing another embodiment of the present invention, which eliminates the above-mentioned drawbacks, in which 32 is an f-V converter, 33 is a changeover switch, winnowing is a drive circuit, and other symbols are This is the same as shown in Figure 1.

In the figure, an f-V converter 32 converts the clock frequency reproduced from the data stroke 1 circuit 20 of the signal reproduction circuit 8 for normal reproduction into a voltage. The changeover switch is controlled by, for example, a microprocessor for system control, and when searching, if the direction command signal is in the RBW direction, the contact point is set to the breath side, and if it is in the FF direction, the contact point is set to b. Operates to close to the side.

The drive circuit 34 has two reference voltages that are selected in accordance with the command of the search direction, and the f-V converter 25 or the f-V converter 32 is controlled depending on these base at pressures and switching of the changeover switch blade. It is composed of a comparator for comparing the output signal of the output signal and an amplifier.

When the search command is in the RBW direction, the comparison error between the f-■ converter 5 and the comparison reference voltage corresponding to the RBW direction is zero, and when the search command is in the FF direction, the comparison error is zero. Change the reference voltage and connect this to fV converter 3
The rotation speed of the cylinder motor 11, that is, the cylinder 4, is controlled so that the comparison error of No. 2 becomes zero.

With the above configuration, when the command in the search direction is REW, the contact of the changeover switch closes to the 1 side, and as in the case of FIG. Using a clock, the cylinder rotation speed is controlled so that this frequency remains constant.

When the search direction command is in the FF direction, the contact of the changeover switch 33 is closed to the b side, and the cylinder rotation speed is controlled using the reproduction clock of the data strobe circuit 20 for normal reproduction so that this frequency is constant. will be done.

FIG. 7 is a diagram showing the relationship between the control of the cylinder rotational speed and the tape running speed when the relative speed of the head and tape is constant according to the embodiment of FIG. 6, and in the REW direction, double speed playback mode is used. In the FF direction, the characteristic (n) can be set as the characteristic (n) using the conventional normal playback mode, so even when performing a 400x high-speed search, the control range of the cylinder rotation speed is 2000 to 4000.
rpm, the dynamic range of the cylinder rotational speed control means 10 can be reduced to 1/2 compared to the case shown in FIG. 1, and the maximum rotational speed can also be lowered, thereby reducing cylinder noise.

The embodiments of the present invention have been described above, and although FIGS. 1 and 6 show an example in which two independent reproduction circuits are provided for normal reproduction and double-speed reproduction, this is not particularly limited. Instead, for example, the equalizer amplifier should be a broadband one that takes double-speed playback into consideration, and the data strobe circuit can be shared by controlling the external voltage-controlled oscillator by switching constants (switching and controlling the free-run frequency). The processing circuit may also be configured to have a single reproducing circuit by switching and controlling the master clock.

In addition, in the embodiment shown in FIG. 6, two systems of f-V converters are provided corresponding to the data strobe circuits for normal playback and double-speed playback, but this is not particularly limited. It is also possible to share the reference value by switching the reference value accordingly.

Further, the tape high speed control means and the cylinder rotation speed control means are also described in Japanese Patent Laid-Open No. 54-136, respectively.
Examples described in Japanese Patent Application Laid-open No. 306 and Japanese Patent Application Laid-Open No. 61-214164 are shown, but these are not particularly limited, and various modifications can be made without changing the gist of the present invention.

〔Effect of the invention〕

As explained above, according to the present invention, the double speed playback function is provided and the high speed search is performed using the double speed playback mode, so that the search speed limit is lowered compared to when using the conventional normal playback mode. The image can be enlarged by 2 times, speeding up the search.

In addition, if the search in the FF direction and the EW direction is shared by using the double-speed playback mode, the control range of the cylinder rotation speed becomes wider, but in contrast, only the search in the RFtW direction can be performed using the double-speed playback mode. The search in the FF direction is performed using the normal playback mode as in the past.

As a result, the control range of the cylinder rotation speed can be greatly reduced, the dynamic range of the cylinder rotation speed control means can be reduced, circuit design etc. can be simplified, and the noise accompanying the rotation of the cylinder can also be reduced. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magnetic recording/reproducing apparatus according to the present invention, and FIG. 2 is a data strobe circuit 20 of FIG.
3 is a diagram showing the input/output characteristics of the PLL circuit shown in FIG. 2, FIG. 4 is a diagram showing the input/output characteristics of the data strobe circuit n in the double-speed reproduction circuit 9 of FIG. The figure shows the relationship between the control of the cylinder rotational speed and the tape running speed when the relative speed between the head and the tape is constant according to the embodiment of FIG. 1, and FIG. 6 shows the configuration of another embodiment of the present invention. 7 is a diagram showing the relationship between cylinder rotational speed control and tape running speed when the relative speed between the head and tape is constant according to the embodiment shown in FIG. 6, and FIG. FIG. 9 is a diagram showing the relationship between the control of the cylinder rotational speed and the tape running speed when the relative speed between the head and the tape is the same as during normal playback. 1m, 1b...Head 2...Tape 7...Tape high speed running control means 8...Normal playback circuit 9...Double speed playback circuit lO
・・・Cylinder rotation speed control means 40 tapes & h8.15 electric ff/s)

Claims (1)

[Claims] 1. In a magnetic recording and reproducing device that records and reproduces information by scanning a magnetic tape with a head mounted on a rotating cylinder, a reel shaft on the supply side or take-up side of the magnetic tape is driven. a tape high-speed running control means for running the magnetic tape at a speed faster than a normal recording/playback speed; a double-speed playback means; and a cylinder rotational speed control means for controlling in both low speed and low speed directions, the frequency of the reproduction signal by the double speed reproduction means in relation to the running speed of the magnetic tape controlled by the tape high speed running control means is set at the time of normal double speed reproduction. 1. A magnetic recording and reproducing apparatus characterized in that the cylinder rotation speed control means is configured to control the cylinder rotation speed so that the rotation speed is the same as that of the cylinder. 2. In a magnetic recording and reproducing device that records and reproduces information by scanning a magnetic tape with a head attached to a rotating cylinder, the reel shaft on the supply side or winding side of the magnetic tape is driven to perform normal recording and reproduction. tape high-speed running control means for running the magnetic tape at a faster speed than the magnetic tape; a double-speed playback circuit; cylinder rotation speed control means for controlling the rotation speed in a direction higher than the rotation speed based on the value of time, and when the running of the magnetic tape controlled by the tape high speed running control means is in the fast forward direction, In relation to the running speed of the magnetic tape, the playback signal by the normal playback circuit is the same as during normal playback, and when the magnetic tape is running in the rewinding direction, the running speed of the magnetic tape is In relation to this, the magnetic recording and reproducing apparatus is characterized in that the cylinder rotation speed control means is configured to control the frequency of the reproduced signal by the double-speed reproduction circuit to be the same as that during normal double-speed reproduction.