JPS6163952A - Tape drive speed controller for magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain a tape drive at a fixed speed by supplying both tape drive speed and direction setting signals to calculate the rotational frequency of a drum motor and comparing a reference voltage proportional to the number of tracks crossing a head with the measured value of voltage to drive a reel motor. CONSTITUTION:The tape drive speed and direction setting signals are supplied to input terminals 10 and 11 respectively and then to an arithmetic circuit 13. A drum FG 12 detects the rotational frequency of a drum motor and supplies it to the circuit 13. The number of tracks crossing a head is calculated by the circuit 13 and supplied to a tape drive control circuit 19 in the form of the reference voltage for tape drive speed. While a counter circuit 18 counts the number of the tracks which actually cross the head. The count value of the circuit 18 is supplied to the circuit 19. The circuit 19 compares both inputs with each other to control a reel motor drive circuit 20. Thus a high and fixed drive speed is secured for a tape.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a tape running speed control device for keeping the tape running speed constant during high-speed tape running in a single-rotation head type magnetic recording/reproducing device.

1. Technical Background of the Invention In recent years, the recording density of tapes used in single-rotation head type magnetic recording and reproducing devices has improved, and many programs are often recorded on the same tape. , 2, it is necessary to perform a program search while running the tape at a higher speed than when recording. When running the tape at high speed, the running speed must be kept constant.

For example, problems arise such as the time required for program search at the beginning and end of tape winding is significantly different. If the tape running speed is several times the recording speed, the capstan motor can run the tape at a constant speed, but if the tape running speed is higher than that, the tape must be run by the reel motor, but 3 tapes are required. In order to run the tape at a constant speed, it is necessary to detect the tape running speed. In general household VTRs, control signals for tracking control are recorded on the control track, so even when running at high speed, this control signal is played back and used as a tape running speed signal to control the tape running speed. It can be set at a constant speed. However, with the increase in recording density.

In order to achieve more precise tracking, a so-called pilot signal is recorded along with the main signal on a diagonal video trunk without using a control signal.

A method of performing tracking control using this signal is being put into practical use. Since such a magnetic recording/reproducing apparatus does not have a control signal, it is not possible to detect the tape running speed using the control signal, so the speed must be detected by other means.

OBJECT OF THE INVENTION The present invention provides a five-rotation head type magnetic recording/reproducing device that can easily detect a tape without any special speed detecting means when the tape is run at high speed during playback without a dedicated track for control signals or the like. An object of the present invention is to provide a tape running speed control device for keeping the running speed constant.

D9 Outline of the Invention A tape running speed setting signal when the tape is run at n times the standard speed during tape playback.

Tape running direction setting signal and drum motor rotation speed N
Calculate the formula Mn = A---B (A, B are constants) n by n, find Mn (the number of tracks that the head crosses during one trace) that should be obtained when the tape runs at n times the speed, and calculate this. A voltage proportional to M I'l is set as a reference voltage, and a voltage proportional to the number of tracks crossed by the head, which is actually detected during tape running, is compared with the reference voltage, and the tape is run at a constant speed based on the comparison result. This is a tape running speed control device for a magnetic recording/reproducing device.

E.1 Embodiment of the Invention A case will be described in which the present invention is applied to a rotating two-head type magnetic recording/reproducing apparatus. FIG. 2 shows a rotating drum section used in the magnetic recording/reproducing apparatus of this embodiment, where 1 is a rotating drum and 2A is a rotating drum section.
and 2B are attached to the drum 1 at angular intervals of 180° and have different azimuth angles, and 3A and 3B are magnets of mutually different polarities and are attached to the drum 1 at angular intervals of 180°. 4 outputs positive and negative drum pulses alternately every half rotation of the drum 1 by the approach of the magnet 3A or 3B to the drum PU (route to the drum pickup). 5 is tape 9 on the circumference of drum 1
It is wrapped over an angular range slightly greater than 0°. Therefore, the main signal to be recorded during one rotation of the drum 1 is time-compressed and recorded on the two tracks.

As described above, as shown in FIG. 3, a length L +
, width T tu + (about θl) are recorded in line in the width direction of the trunk.

FIG. 1 shows a block diagram of an embodiment of the control device of the present invention. In the figure, 10 is an input terminal for a tape running speed setting signal, and 11 is an input terminal 112 for a tape running direction setting signal.
is the drum FC (
The drum frequency generator 13 determines the tape running speed by performing a predetermined calculation based on the tape running speed setting signal, the tape running direction setting signal, and the output of the drum FCl2 (the number of rotations of the drum motor). The arithmetic circuit 14 that generates the base voltage of the tape running speed is connected to the drum FF (), which is set and re-centered by drum pulses.
ram flip-flop).

15 is switched by the output of tram FF14.

A switch 216 that selects and derives the reproduction output of the head 2A or 2B is a reproduction amplifier, and 17 is a waveform shaping circuit that shapes the waveform of the output of the reproduction amplifier 16.

18 is the output pulse of the waveform shaping circuit 17 to the drum FF 14.
19 is a tape running control circuit, 20 is a reel motor drive circuit, and 21 is a reel motor.

With the above configuration, the tape running speed and direction can be arbitrarily set and respective setting signals can be sent to the input terminals 10 and 1.
1 and these signals cause the tape to run at a constant speed. A detailed explanation will be given below with reference to FIG.

A tape running speed setting signal and a direction setting signal are input to input terminals 10 and 11, respectively. When the tape is run at a speed n times the running speed during recording (hereinafter referred to as standard speed), the tape running speed setting signal is a signal corresponding to the absolute value of n, and the tape running direction setting signal is a signal corresponding to the polarity of n. This is a signal corresponding to These setting signals are manually input to the arithmetic circuit 13. Further, the drum FG12 detects the rotational speed Nn of a drum motor (not shown) and generates a signal with a frequency proportional to the rotational speed, and the output of the drum FG12 (i.e., the drum rotational speed N. 13 (the subscript n of the drum rotation speed Nn indicates the time when the tape speed is n times). The arithmetic circuit 13 calculates the number of tracks Mn that one head traverses while tracing the tape once using the following formula % (11).

If the tape is running at standard speed, the head will trace on the same track and will not cross other tracks. FIG. 4 shows the locus traced by the head when the tape runs at high speed in the forward and reverse directions. In the figure (
(a) shows a case where the tape runs at high speed in the forward direction, and (b) shows a case where the tape runs at high speed in the reverse direction, both of which cross a plurality of tracks. As is clear from this, if the number of tracks traversed by the - and gutter during one trace of the tape is constant, then the tape is running at a constant speed.

(Formula 11 will be described in detail later, but the number of tracks M that the heno F crosses at n times speed, and the number of rotations N of the drum motor
+, etc. When the relationship is expressed by equation (1), the tape runs at a constant speed of -. The arithmetic circuit 13 receives the tape running speed setting signal, the tape running direction setting signal, and the actual rotational speed of the drum, calculates equation (1) to find the number of trunks Mn, and further generates a voltage proportional to the number of tracks Mn. do. The polarity of this voltage is positive if the tape is running in the forward direction, and negative if it is in the opposite direction.

On the other hand, a drum pulse synchronized with the drum rotation as shown in FIG. 5 fa) is detected from the drum PU head. One period of this drum pulse is equal to one revolution of the drum, which is also equal to one revolution of the drum motor. Drum pulse is drum FF
14, and the drum FF 14 outputs the pulse shown in the same figure (bl).

The output of the drum FF 14 acts on the isochi 15, and when the output is high level, the reproduction output of the head 2A tracing the tape at that time is derived and input to the reproduction amplifier 16, and the output of the tram FF 14 is low. When the level is
At this time, the reproduction output of the head 2B tracing the tape is derived and input to the reproduction amplifier 16. fc) in the same figure is the output of the reproduction amplifier 16 while the drum makes one-half revolution.

Since the tape is wound around the drum over an angular range of approximately 90°, the output of the reproducing amplifier outputs a voltage with an envelope waveform as shown in the figure only during one-quarter rotation of the drum. This output is caused by the traverse of the trunk. Tiger and Ri are heads with different azimuth angles 2
Since it is recorded alternately with Δ and 2B, it is 71'2
When A (or hen 2B) crosses the tracks, there are every other tracks whose azimuth angle matches that of head 2A (or head 2B). The peak portions of the output waveform of the reproduction amplifier in the figure are outputs from tracks with matching azimuth angles, and the valley portions are outputs from tracks with mismatched azimuth angles. Therefore, the number of mountains is half the number of tracks traversed.

The reproduction output from the two heads or the head 2B amplified by the reproduction amplifier 16 is input to the waveform shaping circuit 17. The waveform shaping circuit 17 detects the envelope of the waveform shown in FIG. 5 (C1), and further slices the detected envelope waveform at an appropriate level.

This is shaped into a rectangular wave and the pulse shown in fd) in the figure is output. The counting circuit 18 includes a drum F shown in FIG.
The output of F14 and the output of the waveform shaping circuit 17 shown in FIG. 3(d) are input. The counting circuit 18 counts the output pulses of the waveform shaping circuit 17 in units of 1/2 rotation period of the drum, which is the output of the drum FF 14, and after counting is completed, holds and outputs a voltage proportional to the counted value, and performs counting. Results will be reset.

During the next 1/2 rotation period of the tram, the counting circuit newly counts the output pulses of the waveform shaping circuit 17 and holds a voltage proportional to the counted value, but immediately before that, the output voltage held in the previous period is The hold is released. As described above, the output voltage of the counting circuit 18 is a voltage proportional to the number of peaks in the envelope waveform of the head playback output that occurs during one-quarter rotation of the drum, and as the number of peaks increases, it becomes 5, which means that the tape runs at high speed. (in the forward or reverse direction), the output voltage of the counting circuit 18 increases.

The tape running control circuit 19 receives the output of the counting circuit 18, the output of the arithmetic circuit 13, and a tape running direction setting signal. The output of the arithmetic circuit 13 is the number Mn of trunks that the head crosses while tracing the tape once when the tape is running at high speed, calculated by equation (1), and the output of the counting circuit 18 is the number Mn of trunks that the head crosses while tracing the tape once. is about half the number of tracks crossed, and the tape running direction setting signal indicates the direction in which the tape should run. Tape running control circuit 1
Reference numeral 9 halves the output of the arithmetic circuit 13 and uses this as a reference voltage for tape running speed. If the tape running direction is in the opposite direction, the result of equation (1) will be negative.

The loss potential is reversed by the tape running direction setting signal and used as a reference voltage. The output of the counting circuit 18 is compared with the reference voltage, and the difference voltage is outputted from the tape running control circuit 1iA19, and this output is passed through the reel motor drive circuit 20 to control the reel motor 21.

The tape is therefore run at a constant speed. A tape running direction setting signal is input to the reel motor drive circuit 20 to control the rotational direction of the reel motor 21, that is, the tape running direction.

When the tape is run at n times the standard speed as described above, the set tape speed and direction and the actually detected rotational speed N of the drum motor. (11) to calculate Mn (the number of tracks that the head crosses during one trace) obtained at n times the speed, and this calculated Mo
(2) The number of tracks crossed by the head, which is actually detected during tape running, is compared, and the tape running speed is held constant based on the comparison result. This is the basis (11
The formula will be explained below. The following symbols are used in this explanation:

D: Drum diameter φ: Tape winding angle Vo: Tape running speed No. 2 Drum rotational speed θn: Trace of the head on the tape! T! The angle of the lt trace.The subscript n is double the speed compared to the standard speed.

That is, n=1 is at standard speed, and n-0 is at stop.

The polarity of n is positive when the tape is running in the forward direction, and negative when it is running in the reverse direction.

FIG. 6 shows a tape, Ho and HI are the trajectories traced by the head, Ha is when the tape is stopped, and Hn is when the tape is running at n times the speed.

Also, Ha and 119. The length of each is Lo.

Ln, and Ll shown in FIG. 3 is Ln of n=
This is the case of 1. Furthermore, the angle of Ho with respect to the tape is θ
0, and θ1 shown in FIG. 3 is I(,.

This is the case of the back roll l at an angle θ1 with respect to the tape.

When the tape is running at n times the speed, 1' ram is θ/2
Distance traveled by the tape during π rotation +1SIt 1 .

It can be expressed as On the other hand, when the hemlocks are mounted on the drum at equal intervals, each trunk has a V length along the length of the tape.
Since one line is recorded for each + / k N +,
While the drum rotating at the rotation speed Nn rotates at θ/2π during high-speed tape running, the number of tracks M Hl is 11gJ.
becomes MI, so substitute equation (2) into equation (3), and then calculate ■.

Since is n F of the standard speed V+, it becomes 2πN IN 2π Nn 2 π. In equation (4), n and N are constants other than n, so equation (4) becomes M, = A・---B ・・・・・・・・・(5) Nn, which is the above +11 It is a formula.

The above equation <, +51 is the number of trunks that the head crosses when the drum rotation speed is Nn and the tape is run at n times the speed in the forward and reverse directions, so the tape running speed should be controlled so that it becomes the equation (5). For example, the tape can be run at a constant speed.

Note that since the tape running speed is detected as a digital value called the number of tracks crossed by the head, there is an error in comparing it with the calculation result obtained from equation (5), but the speed at which the tape is run by the reel motor Since the number of tracks traversed by the hennode is large in the range, the above-mentioned error does not pose a problem in practice.

In this embodiment, it is assumed that the drum rotation speed Nn when the tape is running at high speed is different from the rotation speed N1 when the tape is running at the standard speed, and the actual drum rotation speed Nn at n times the speed is detected, and this detected value is used to calculate (5 ), but if the number of drum rotations at n times speed is known in advance, (
5) Instead of formula, Mn=A'n-B...------
- Mn can be calculated using (6) (here, A'=A/Nn, which is a constant). moreover.

If the drum rotation speed is always constant and equal to the rotation speed at standard speed, MI, -B(n-1
)...Mn can be calculated using (7). When calculating the number of tracks that the head crosses when the tape runs at n times speed using equation (6) or equation (7), the output of the drum FG 12 that is input to the calculation circuit 13 is omitted in Figure 1. can do.

In the embodiment shown in FIG. 1, the tape running speed setting signal and the tape running direction setting signal are added to the input terminals 10 and 11, respectively, and are manually inputted to the arithmetic circuit 13. Any setting signal may be inputted only to the input terminal IO with loss protection. If you do this,
If the tape running direction setting signal is separated and extracted from the input terminal 10 and applied to the tape running control circuit 19 and the reel motor drive circuit 20, the input terminal 11 can be omitted.

Further, the output of the arithmetic circuit 13 is a positive or negative voltage according to the m formula (or formula (6) or formula (7)), but if the absolute value of this voltage is output from the arithmetic circuit 13, the tape The tape running direction setting signal applied to the running control circuit 19 can be omitted.

According to the present invention, when the tape is run at high speed during playback, the reel motor is controlled using the calculation result based on the tape running speed setting signal, the tape running direction setting signal, and the tram rotational speed as a reference voltage. Since the tape running speed is detected based on the number of tracks crossed by the tape, it is possible to run the tape at a constant speed in a simple manner and without providing any special speed detection means.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, Fig. 2 shows a rotating drum Has used to explain this embodiment, Fig. 3 shows a recording trunnoid 7 used to explain this embodiment, and Fig. 4 shows an example of this embodiment. FIG. 5 is a waveform diagram of various parts used to explain this embodiment, and FIG. 6 is a detailed explanatory diagram of the present invention. 12 Nidram FC, 13: Arithmetic circuit. 14 Nidrum FF, 16: Playback amplifier.

Claims (4)

[Claims] (1) Input means for inputting tape running speed setting signal and tape running direction setting signal, and drum motor rotation speed N_n
M based on the signal ±n obtained from the input means and the signal Nn obtained from the detection means;
Perform the calculation _n=A・n/N_n-B (A and B are constants), and calculate the number of tracks M_ that the head crosses as a result of this calculation.
a generating means for generating a reference voltage proportional to n; a generating means for counting the number of tracks actually crossed by the head and generating a voltage proportional to the counted value; and an output voltage of the generating means and a generating means for generating the reference voltage. Comparing means for comparing the absolute value of the output voltage, and driving means for driving the reel motor using the output of the comparing means and the tape running direction setting signal,
A tape running speed control device for a magnetic recording/reproducing device characterized by running a tape at a constant speed. (2) When the output of the reference voltage generating means is a voltage proportional to the absolute value of the calculation result of the formula M_n=A・n/N_n−B, the comparing means compares this voltage with the track actually crossed by the head. 2. A tape running speed control device for a magnetic recording/reproducing device according to claim 1, wherein the device is a comparison means for comparing a voltage proportional to a count value of . (3) When the drum rotation speed N_n corresponding to n is predetermined, the reference voltage generating means uses the formula M_
2. The tape running speed control device for a magnetic recording/reproducing device according to claim 1, wherein the operation is performed according to n=A'·n-B (A' and B are constants). (4) When the drum rotation speed N_n is always constant and is N_1, the reference voltage generating means uses the formula M_n=B(n-1).
2. A tape running speed control device for a magnetic recording/reproducing device according to claim 1, wherein the tape running speed control device performs calculation according to the following equation (B is a constant).