JPH05120768A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To keep the relative speed between a tape and a head constant by temporarily controlling the drum by the control signal of a pseudo-tape speed output means until the tape speed reaches a prescribed value during a search start. CONSTITUTION:When a search starts, a tape running speed detection means 8 simultaneously measures the rotational period of a reel and the tape running speed operation is initiated by the measurement result and the discrimination result of a tape length discriminating means 7. When the tape speed reaches the prescribed value, an end signal is outputted to a microprocessor 15. When the processor 15 receives the signal from the means 8, the control signal from a revolving speed controlling means 10 is changed from the signal of a pseudo- tape speed output means 9 to the output of the means 8 in order to switching control a switching means 25 and controls the number of revolution of a drum motor 11. Thus, from the starting of a search, the relative speed between the tape and the head is kept constant and a high precision search without skipping signal reading is executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head type digital audio tape recorder (hereinafter referred to as DAT), and particularly when a tape is running at high speed from the result of measuring the rotation cycle of the reel base on the tape supply side and the winding side. The present invention relates to a magnetic recording / reproducing apparatus having a configuration in which the running speed of the drum is calculated and the number of rotations of the drum is controlled so that the relative speed of the head and the tape becomes constant according to the result.

[0002]

2. Description of the Related Art In a rotary head system DAT, when a random music selection (cue to a music piece) is performed at a speed of several tens to several hundred times the normal reproduction speed, a signal indicating the start of a music piece recorded in a track or It is necessary to accurately read a control signal recorded at the same recording density as the music PCM signal, such as a signal for displaying time and a music number information signal, when the tape is running at high speed. For that purpose, the relative speed between the head and the tape is always the same as during normal recording / reproduction, or the relative speed deviation between the head and the tape is normally in a data strobe circuit (a circuit for reproducing a digital signal from a signal reproduced by the head). It is indispensable to control the drum rotation speed according to the running speed of the tape so that the allowable jitter is within about ± 10%.

The relationship between the tape running speed and the number of rotations of the drum for keeping the relative speed between the tape and the head constant with respect to the tape running speed will be described below. The relative velocity V ₀ between the tape and the head at the time of normal recording / reproduction is expressed by the _equation 1.

[0004]

[Equation 1]

Here, V _H0 is the rotational speed of the head or drum during normal recording / reproduction, θ is the inclination angle of the track on the tape, and V _T is the tape running speed during normal recording / reproduction.

On the other hand, the relative speed V when the tape is run at n times the normal recording / reproducing speed is FF (fast forward).
Number 2 when traveling in the direction, REW (rewind)
When the vehicle is run in the same direction, it is expressed by Equation 3.

[0007]

[Equation 2]

[0008]

[Equation 3]

FIG. 6 shows the relationship between the tape rotation speed nV _T and the number of drum revolutions when the relative speed V of the _equations 2 and 3 is equal to the relative speed V ₀ of the _equation 1 during normal recording and reproduction. Is. In order to maintain the same relative speed as during normal recording and reproduction, for example, when the tape is run at 200 times,
In the FF direction, the drum speed is 3000 rpm, and RE
In the W direction, control to 1000 rpm is necessary.

As an apparatus for controlling the relative speed of the tape and the head by changing the number of rotations of the drum according to the running speed of the tape in this way, for example, Japanese Patent Application No. 63-23496.
There is one described in Japanese Patent No. This device indirectly detects the running speed of the tape by detecting the rotation speed of the reel base on the tape supply side and the winding side, and the relative speed of the head and the tape relative to this tape running speed during normal recording and reproduction. The number of rotations of the drum is controlled so as to be constant with the same value.

By the way, in the prior art, the tape speed must be calculated by measuring the rotation cycle of both reel bases (the calculation is possible even if the cycle of each reel FG wave is measured, but the reel base eccentricity). Therefore, there is a drawback in that the calculation error becomes large when the tape is started up at a slow tape speed during search. In other words, the start-up of the tape speed in the high-speed search cannot be started at a high speed such as 200 times at a stroke considering the damage of the head and tape and the followability of the drum rotation speed, and the soft start is adopted. Is common,
Therefore, if the tape speed is calculated by measuring the rotation cycles of both reels, there is a problem in that the actual speed cannot be accurately detected due to a delay in the calculation while the tape speed is low. FIG. 7 shows this state, and shows the calculation delay when the tape speed is calculated by measuring the reel rotation cycle in the case of performing the soft start at 200 times speed / 3s.
The calculation delay is maximized at the tape start end (or the end) at which one reel rotation cycle is maximized, and FIG. 7 shows this condition. When the tape is started at 200 times speed / 3s, the S reel rotates about 22 times before the tape speed reaches 200 times speed, and the average rotation cycle is about 0.15s. Is long. Especially at the start, it takes about 0.6 s per revolution,
The tape speed at the time of completion of rotation (at the time of completion of measurement of one cycle) reaches about 40 times. In other words, the tape speed can be calculated for the first time at point a when 0.6 s has elapsed from the start of the search, and the tape speed is calculated later with each reel rotation at the timings of b, c ... A large calculation error will occur depending on the difference from the calculated value simulated by the broken line. Especially, the calculation error just before the point a is about 10% in terms of the relative speed deviation between the tape and the head.
However, there is a drawback that the drum rotation speed cannot be accurately controlled, and the signal cannot be read correctly.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks, eliminate the influence of calculation delay even when the reel rotation cycle is long at the time of tape startup, and keep the relative speed between the head and the tape constant. Another object of the present invention is to provide a magnetic recording / reproducing apparatus which can be kept at

[0013]

The above-mentioned object is to provide a pseudo tape speed output means for outputting speed data that matches a preset soft start characteristic, so that the tape speed is set to a predetermined value in a slow tape speed period at the start of search. It is achieved by temporarily controlling the drum by the control signal of the pseudo tape speed output means until the value is reached (the rotation of both reels ends a predetermined number of times).

[0014]

The tape reproducing means runs the tape at the normal reproduction speed or at an arbitrary constant speed n times the normal reproduction speed. At this time, the tape length discriminating means measures the rotation cycle of both reels, and discriminates the length of the mounted tape from the result.

The tape high-speed running control means responds to the tape running direction so that the sum of the rotational speeds of both the tape supply side and take-up side reel stands, which is well known (described in Japanese Patent Laid-Open No. 54-136306), is constant. It controls the rotation speed of the reel stand on the winding side, and the tape is run at a high speed at a predetermined speed.

The tape running speed detecting means measures the rotation cycle of both reels during high speed running of the tape, and calculates the tape running speed based on the result and the result of the above judgment of the tape length. It outputs a predetermined control signal according to the tape running speed.

The pseudo tape speed output means outputs a pseudo control signal corresponding to a tape speed that matches a preset soft start characteristic while the tape running speed detecting means finishes a predetermined number of times from the start of the search.

The switching means sends a control signal from the pseudo tape speed output means to the drum rotation speed control means from the start of the search until the tape speed reaches a predetermined value, and after the tape speed reaches the predetermined value, The control signal switching control is performed so that the control signal from the tape traveling speed detection means is sent to the drum rotation speed control means.

The drum rotation speed control means receives the control signals from the tape running speed detection means and the pseudo tape speed output means, and operates to variably control the rotation speed of the drum in accordance with the control signals.

With this configuration, if the drum rotation speed control means is set so that the drum rotation speed controlled by the control signals from the tape running speed detecting means and the pseudo tape speed output means, the tape running speed is set. Even when the tape speed is slow and the output speed of the control signal from the speed detecting means is delayed, the drum rotation speed can be controlled to be constant relative to the tape speed, and the relative speed between the head and the tape can be kept substantially constant. ..

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the figure, 2 is a magnetic tape, 3 is a rotary drum, 1
a and 1b are a pair of rotary magnetic heads having mutually different azimuth angles, 4 is a tape supply side reel stand, 5 is a tape take-up side reel stand, 6 is a tape supply side reel stand FG16 and a tape take-up side reel stand FG 17 and f-V converter 18, 1
9, a tape high-speed running control means including a drive circuit 21 and a reel motor 22 for driving the reel stand 4 or 5, 7 is a tape length determining means, 8 is a tape running speed detecting means, and 9 is a pseudo. Tape speed output means, 10 is drum rotation speed control means, 11 is a drum motor, 12 is a capstan motor 13, and a capstan servo circuit 14
Also, tape reproducing means including the system control microprocessor 15, 23 is a capstan, 24 is a pinch roller, and 25 is a switching means for switching the control signal of the drum rotation speed control means.

The configuration and operation of each section will be described below. The tape high speed running control means 6 is disclosed in JP-A-54-136.
An example equivalent to the publication No. 306 is shown. The fV converters 18 and 19 are composed of, for example, a well-known monostable multivibrator and an integrating circuit, and are reel FG signals obtained in synchronization with the rotations of the tape supply reel stand 4 and the tape winding reel stand 5, respectively. The 16 and 17 frequency signals are converted to a voltage. The adder 20 is composed of, for example, an adding circuit using resistors, and adds the output signals of the fV converters 18 and 19. The drive circuit 21 includes a comparator that compares a predetermined reference voltage with the output signal of the adder 20, an amplifier, and the like.
A reel motor 22 that drives the reel base 4 or 5 so that the comparison error between the reference voltage and the output of the adder 20 becomes zero.
Controls the number of revolutions. With such a configuration, the output of the adder 20 matches with the setting of the reference voltage of the drive circuit 21, that is, the sum of the rotational speeds of the tape supply side reel base 4 and the tape winding side reel base 5 is the reference. Since the rotation speed control of the reel motor 22 works so as to be equal to the voltage,
The tape is run at high speed at an arbitrary speed according to the setting of the reference voltage. When the tape is running at high speed, the pinch roller 24 is opened by the mechanism control.

The tape length discriminating means 7 measures the rotation cycle of the tape supply side reel stand 4 and the tape winding side reel stand 5 when the tape is running at a constant speed, and the length of the mounted tape is determined from the result. Then, the identification signal Es is output. It should be noted that, when the tape is run at a known constant speed, it is possible to obtain the length of the mounted tape by calculation by measuring the rotation cycle of both reels.
Since it is publicly known as described in Japanese Patent No. 234963, its details are omitted.

The tape running speed detecting means 8 measures the repetition period of both reel stands from the tape supply side reel FG16 and the tape winding side reel FG17 during high speed running of the tape, and the result and the mounting which is discriminated by the tape length discriminating means. Calculate the tape running speed based on the result of the tape length,
The control signal Ev corresponding to this is output. If the length of the tape to be mounted is known by the tape length discriminating means 7, it is possible to calculate the absolute running speed of the tape by measuring the rotation cycle of both reel stands.
Since it is publicly known as described in Japanese Patent Publication No. 234963, detailed description thereof will be omitted. However, the tape running speed detecting means 8 determines the tape speed according to the calculated tape speed value, for example, as shown in FIG. Evo for normal playback,
Also, with this as a sakai, when the tape running is in the FF (fast forward) direction, it descends according to the tape speed, and when it is in the REW (winding) direction, it rises according to the tape speed. Is configured to output the control signal. The system control microprocessor 15 determines whether the tape is traveling in the FF direction or the REW direction by the key operation of the device, and a control signal corresponding to the direction is input to the tape traveling speed detecting means 8. Made by

When the search operation command key is operated, the pseudo tape speed output means 9 operates so as to output the control signal Gv shown in FIG. 3 according to the preset soft start characteristic. That is, as shown by the solid line in FIG.
= 0, when Gvo is the starting point and the soft start of the tape startup is 200 times / 3 sec, a control signal that changes linearly to Gvf at t = 3 sec in FF search and Gvr in REW search When the start is 200 times / 2 sec as shown by the alternate long and short dash line, at t = 2 sec, both FF and REW searches operate to output control signals according to the soft start characteristics that change to Gvf and Gvr, respectively.

The switching means 25 is controlled by the system controlling microprocessor 15, and outputs Gv of the pseudo tape speed output means 9 and output E of the tape running speed detection means 8.
The control signal Ec is output to the drum rotation speed control means 10 by switching v. When the search operation command key is operated, the contact of the switching means 25 is controlled by the system control microprocessor 15 so as to be connected to the solid line side shown in FIG. The calculation of the tape running speed indicated by is started. Then
When the tape running speed detecting means 8 performs a predetermined number of times according to the running of the tape, that is, when the tape speed reaches a predetermined value, the system controlling microprocessor 15 recognizes the identification signal from the tape running speed detecting means 8 and switches it. Means 2
The contact point 5 serves to switch from the solid line side in FIG. 1 to the broken line side. Therefore, the control signal E to the drum speed control means 10
c is that Gv having the characteristic shown in FIG. 3 is supplied at the start of the search, and Ev having the characteristic shown in FIG. 2 is supplied after the reel stand has rotated a predetermined number of times after a lapse of a predetermined time from the start of the search. Become.

When the reproducing operation command key is operated while the cassette is mounted in the apparatus, the tape reproducing means 12 starts the operation of the capstan servo circuit 14 by the control signal of the system controlling microprocessor 15.
The capstan motor 13 is rotated to drive the capstan 23 directly connected to the capstan motor 13 and the tape take-up side reel stand 5 connected through a gear or the like in the tape take-up direction so that the tape is rotated at the rotational speed of the capstan 23. I will run. The tape speed at this time is 8.1 which is the tape running speed during normal reproduction.
An arbitrary speed of 5 mm / sec or an integral multiple of this is set. Of course, at the same time as the operation of the capstan servo circuit 14 is started, the pinch roller 24 is pressed against the capstan 23 by mechanical control.

The drum rotation speed control means 10 comprises a switching means 2
The drum motor 1 according to the control signal Ec output from
The rotation speed of 1 is controlled. FIG. 4 shows a specific configuration example of the drum rotation speed control means 10. In the figure, 26 is an FG directly connected to the drum motor 11, 27 is an fV converter, and 28 is a comparison amplifier. The fV converter 27 converts the input signal frequency f of the FG 26 into a voltage. The comparison amplifier 28 is shown in FIG.
The control signal Ec output from the switching means 25 and the output signal Ef of the fV converter 27 are comparatively amplified, and the rotational speed of the drum motor 11 is controlled so that the comparison error becomes zero. With such a configuration, the control signal Gv having the characteristic shown in FIG. 3 is output from the switching means 25 according to the traveling direction and the speed of the tape while the tape speed is low, and the characteristic shown in FIG. Since Ev is input, the rotation speed of the drum motor 11 is controlled according to the value of Gv or Ev on the input / output characteristics of the fV converter 27 as shown in FIG. Therefore, for example, in the case of configuring a high speed search of 200 times, the drum rotation speed is 3000 rpm in the FF direction and 1000 rpm in the REW direction as shown in FIG.
Therefore, in the characteristics of the fV converter of FIG. 5, the fV converter output Ef when the drum rotation speed is 3000 rpm and 1000 rpm, and when the normal reproduction is 2000 rpm is Eff, Efr, and Efo, respectively. For example, this value and Gvf, Gvr, Gvo shown in FIG. 3 and E shown in FIG.
If the characteristics of the pseudo tape speed output means 9 and the tape running speed detecting means 8 are set so that vf, Evr, and Evo are the same, the drum rotation speed corresponding to the tape running speed is the relative speed between the tape and the head. Is always constant.

As described above, the configuration of each part in the embodiment of FIG.
The operation has been described. With such a configuration, when the reproduction operation command key is operated while the tape is mounted on the reproduction device, the tape is run at the normal reproduction speed or a constant speed that is an integral multiple thereof. At this time, the tape length discriminating means 7 operates to discriminate the length of the mounted tape.

Next, when the search operation command key is operated and the tape high speed running control means 6 starts to drive the tape, the pseudo tape speed output means 9 outputs the control signal shown in FIG. Since the signal is supplied to the drum rotation speed control means 10 through the switching means 25, the rotation speed of the drum motor 11, that is, the drum 3 is controlled so that the relative speed of the heads 1a and 1b with respect to the tape is always constant. Note that the soft start control for starting the search is configured by, for example, giving the drive circuit 21 its function, although details thereof are omitted.

Simultaneously with the start of the search, the tape running speed detecting means 8 starts measuring the rotation cycle of both reel bases on the tape supply side and the winding side, and based on this measurement result and the judgment result of the tape length judging means 7. The calculation of the tape running speed is started. Then, the tape speed is a predetermined value from the start of tape running,
That is, when the calculation by the tape running speed detecting means 8 is completed a predetermined number of times, the tape running speed detecting means 8 outputs this end signal to the system controlling microprocessor 15.

System control microprocessor 15
Recognizes the tape speed predetermined value reaching signal outputted from the tape running speed detecting means 8, and controls the switching means 25 so that the control signal of the drum rotation speed controlling means 10 is transmitted from the pseudo tape speed outputting means 9 to the tape. It is switched to the output of the traveling speed detecting means 8. As a result, after the tape speed reaches a predetermined value from the start of the search, the control signal shown in FIG. 2 is supplied to the drum rotation speed control means 10 so that the relative speed of the head and the tape becomes constant. Rotational speed control is performed.

The specific timing at which the control signal of the drum motor rotation speed control means 10 is switched from the pseudo tape speed output means 9 to the output of the tape running speed detection means 8 is the calculation delay shown in FIG. It may be near the start of the search, which is a problem, and is set at point a or point b at which the calculation by the tape running speed detecting means 8 is completed two to three times.

The embodiments of the present invention have been described above.
In the embodiment shown in FIG. 1, the tape length discriminating means 7, the tape running speed detecting means 8 and the pseudo tape speed outputting means 9 are provided independently of each other, but this is not particularly limited and, for example, 1 It can also be shared by using one microprocessor or the like. As the tape high speed running control means, the one described in JP-A-54-136306 has been taken as an example, but is not particularly limited. Also, regarding the drum rotation speed control means, an example in which the reference voltage of the comparison amplifier is variably controlled by a control signal according to the tape speed has been shown, but this is not particularly limited, and for example, a digital servo In the circuit, the clock frequency of the servo circuit can be variably controlled by a control signal according to the tape speed, and various modifications can be easily made within the scope of the present invention.

[0036]

As described above, according to the present invention, the tape speed is calculated from the reel rotation period, and the relative speed between the tape and the head becomes the same as that during normal recording / reproducing in accordance with the result. In a magnetic recording / reproducing apparatus for controlling the number of rotations of a drum, during the period of a slow rising of the tape speed where the output of the control signal from the tape running speed detecting means at the time of starting the high speed search is delayed, the head and the tape are matched with the tape starting characteristics. Since the drum rotation speed is controlled by a pseudo control signal that keeps the relative speed of the tape constant, even when the reel rotation cycle is long at the start of the search and the tape calculation is slow,
This effect can be eliminated and the relative speed between the tape and the head can be kept substantially constant, so that it is possible to realize a highly accurate magnetic recording / reproducing apparatus that does not skip signals.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a control signal output from the tape running speed detection means.

FIG. 3 is a characteristic diagram of a control signal output from the pseudo tape speed output means.

FIG. 4 is a block diagram of drum rotation speed control means.

5 is a characteristic diagram of the fV converter of FIG.

FIG. 6 is a relationship diagram between tape speed and drum rotation speed.

FIG. 7 is a diagram illustrating a tape speed calculation delay.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Head, 2 ... Tape, 3 ... Drum, 6 ... Tape high speed running control means, 7 ... Tape length determination means, 8 ... Tape running speed detecting means, 9 ... Pseudo tape speed output means, 25 ... Switching means, 10 ... Drum rotation speed control means, 12 ... Tape reproducing means.

Claims (1)

[Claims] 1. A magnetic recording / reproducing apparatus for recording / reproducing information by scanning on a magnetic tape by a head mounted on a rotary drum, wherein a reel shaft on a supply side or a winding 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, and a tape playing means for running the magnetic tape at a predetermined speed;
When controlling the tape running by the tape reproducing means, the rotation period of the reel side of the supply side and the winding side of the magnetic tape is measured, and the length of the magnetic tape is determined by calculation based on the measurement results. Means and the rotation cycles of the reel bases on the supply side and the winding side of the magnetic tape, and based on the measurement results and the tape length determination result by the tape length determination means, the tape high speed running control means Is a tape running speed detecting means for calculating a running speed of the magnetic tape during high speed running and outputting a control signal according to the running direction and the running speed of the magnetic tape, and a calculation result of the tape running speed detecting means. Drum rotation speed control means for controlling the rotation speed of the rotating drum in relation to the tape running speed, and the relative speed between the tape and the head becomes constant during high speed running of the magnetic tape. In the magnetic recording / reproducing apparatus configured to control the number of rotations of the drum, the pseudo tape speed output means for outputting pseudo data of the tape running speed, the tape running speed detecting means and the pseudo tape speed output means are output. And a switching means for controlling the switching of the tape. The tape is output by the pseudo tape speed output means until the tape speed reaches a predetermined value at the time of starting the tape at high speed, and after the tape speed reaches a predetermined value. The magnetic recording / reproducing apparatus is characterized in that the switching means is controlled so as to drive the drum rotation speed control means by the output of the tape running speed detection means.