JPS6129447A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To control the running speed of a magnetic tape by using a sample pulse generated via an output of a synchronizing signal detection circuit so as to sample output information of a detection circuit of a tracking signal and applying running speed control of the magnetic tape to obtain stably a tracking error signal. CONSTITUTION:An RF reproducing signal is inputted to filters 15, 16 of a synchronizing signal detection circuit 9 and a detection circuit 11 via an amplifier 14. A synchronizing signal from the filter 15 is compare with a reference level VS at a comparator 17 via a rectifier circuit 16 and inputted to a sample pulse generating circuit 10. A switch 29 is turned off by a sample pulse from an OR circuit 22 of the circuit 10, a tracking signal from the filter 23 is inputted to the tracking detection circuit 12, switches 31, 32 are turned on by a pulse from pulse generating circuits 21a, 21b, inputted to an adder 35 via voltage followers 34a, 34b, and a tracking error signal TE being a difference output is inputted to a speed control circuit 7 to perform speed control of the magnetic tape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording and reproducing device that can be used in digital audio tape recorders, video tape recorders, etc., and in particular, its automatic tracking method % type % Structure of conventional examples and problems thereof In conventional video tape recorders, etc., a control head dedicated to tracking is provided for tape tracking, and during recording, the control head records a reference pulse, and during playback, the frequency of the playback signal of the reference pulse reproduced by the control head is set. The usual method was to compare the phase of the reference frequency and control the capstan motor for tracking. This method has problems in that the control head installation is easily distorted due to accuracy, temperature changes, and changes over time, and there is also large variation among manufacturers. It was a hindrance.

To solve this problem, the control head is omitted and instead, like an 8mm VTR, a pilot signal is written in the form of FM modulation over the entire video track during recording as tracking information. An ATF method that controls the tape running speed by controlling the capstan motor so that the amplitudes of the two difference frequency signals detected from the two leaking pilot signals and the pilot signal of the own track are equal, and performs tracking. is proposed. However, since digital audio tape recorders and the like require wideband recording information, it is necessary to record tracking information separately from audio digital data. However, the ATF like the conventional 8 + oa + video tape recorder
This method requires a filter with a large time constant, necessitates a large recording area for tracking information on the track, and has the problem that a large recording area for audio digital data cannot be secured. Furthermore, if the tracking information recording area is made small, the sample pulse of the tracking signal must be made small, and a detection circuit with a large time constant cannot be used. Furthermore, when a detection circuit with a large time constant is used, there is a problem in that the output tends to become unstable.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a magnetic recording and reproducing device that has a small pilot signal area recorded on a track, stably obtains a tracking error signal, and can control the running speed of a magnetic tape. That's true.

Structure of the Invention The magnetic recording and reproducing apparatus of the present invention is a magnetic recording and reproducing apparatus that records and reproduces information by forming tracks in a helical shape on a magnetic tape using a rotating head. A tracking information area for recording tracking information of a certain length is provided, a tracking signal for tracking information detection and a synchronization signal for tracking information reading synchronization are recorded in the tracking information area, and synchronization signal detection for detecting the synchronization signal. a sample pulse generation circuit for generating a pulse with the output of the synchronization signal detection circuit; and a detection circuit that inputs the tracking signal and is capable of changing a time constant with the output pulse of the sample pulse generation circuit. and a tracking detection circuit that samples and detects the output information of the detection circuit using the output pulse of the sample pulse generation circuit, and controls the running speed of the magnetic tape using the output signal of the tracking detection circuit. Accordingly, the area occupied by the pilot frequency signal recording area in the track can be reduced, and stable tracking control is possible.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of the main parts for explaining the tracking method (ATF) of the magnetic recording and reproducing apparatus of the present invention, in which (1) shows a cylinder that holds heads (1a) and (1b) and rotates at high speed; 2) a motor for rotating the cylinder (1); (3) a position detector for detecting the rotational phase of the cylinder (1) and the rotational positions of the heads (1a) and (1b); (4) is the motor (2)
The motor (2), that is, the cylinder (
1) is rotationally controlled in phase synchronization with the reference frequency fs.

(5) is a capstan motor, (6) is a frequency generator for detecting a frequency proportional to the rotation speed of the capstan motor (5), (7) is a speed control circuit, (8) is an addition circuit, ( 9) a synchronization signal detection circuit for detecting a synchronization signal necessary for detecting a tracking signal during playback;
(10) is a sample pulse generation circuit that generates a pulse from the detection output of the synchronization signal detection circuit (9) at the timing of starting detection of a synchronization signal and a certain period of time after the start timing, and (11) inputs a tracking signal. The detection circuit (12) changes the time constant with the pulse from the sample pulse generation circuit (10) and rectifies the tracking signal and outputs it. This is a tracking detection circuit that samples the output tracking signal and detects tracking errors. The capstan motor (5) constitutes a speed control loop together with the frequency generator (6) and the speed control circuit (7), and is controlled to be approximately synchronized with the rotation speed proportional to the rotation speed of the cylinder (1). A synchronous signal detection circuit (9) detects a tracking signal from track information detected from a magnetic tape (13) by two heads (1a) and (1b) disposed facing each other at an angle of 180 degrees on the outer periphery of a cylinder (1). A tracking detection circuit (12) samples a tracking signal from the track information detected by the head (la) (lb) in synchronization with the synchronization signal to generate a tracking error signal. This tracking error signal is sent to the adder circuit (
8) to the speed control loop through the head (la
) The capstan motor (5) is controlled to zero the tracking error signal obtained from the track information detected by (lb), and as a result the tape speed is controlled.

Figure 2 shows an example of a track pattern recorded on the tape (13), which is alternately reproduced by the two heads (la) and (Ib) in Figure 1, where ■ records audio, music information, or image information. area, F is an area for recording pilot frequency signals for obtaining tracking information (hereinafter referred to as ATF)
area).

In the example shown in FIG. 2, there is one tracking area F for one track, but it is also possible to have a plurality of tracking areas F as described later.

Figure 3 shows the ATF area in more detail. In the AI track recorded by the head (1a), f□ is the constant period pilot signal, and in the B1 track recorded by the head (1b), f2 is the fixed period pilot signal. That is, it is recorded as an ATF signal. This track pattern of A1°B1 is recorded as one unit, and this pattern is recorded repeatedly thereafter. H is the head gap of the head running on the track A1, and in FIG. 3, the head gap is slightly wider than the track width. In Figure 3, fl
is used as a synchronization signal, and f2 is used as a tracking signal. It goes without saying that fi and f are the same no matter which one is used as the synchronizing signal.

FIG. 4 is a block diagram showing a specific configuration example of the synchronization signal detection circuit (9), sample pulse generation circuit (IO), detection circuit (11), and tracking detection circuit (12) in FIG. And FIG. 6 is a time chart for explaining the operation.

In FIG. 4, (14) is the head (l) shown in FIG.
a) An amplifier to which (lb) RF output is temporally applied and amplifies it, (15) is a filter that separates the synchronization signal from signals of other frequencies, (16) is a filter (15)
The rectifier circuit (17) detects the output of the rectifier circuit (16
) is a comparator that compares the output of the reference level Vs with the reference level Vs, and these constitute a synchronization signal detection circuit (9).

Also, in Figure 4, (18) (20a) (20
b) is a delay circuit made by a monostable multivibrator etc. (19a) (19b) (21a)
(21b) is a pulse generation circuit that generates a pulse at the rising edge of an input signal, and (22) is an OR circuit, which constitute a sample pulse generation circuit (10).

In addition, in FIG. 4, (23) is a filter that separates and extracts the tracking signal, (24) (27) (2
8) is a resistor, (25) is a diode, (26) is a capacitor, (29) is a switch that operates with the output of the OR circuit (22) of the sample pulse generation circuit (10), and (30) is a switch that controls the input voltage. This is a voltage follower that outputs the voltage as it is, and these constitute a detection circuit (11).

Similarly, in FIG. 4, (31) and (32) are the pulse generation circuit (21a) of the sample pulse generation circuit (10).
' (21b) operates with the pulse generated by the detection circuit (1
1) The tracking signal amplitude output from capacitor (3
3a) A switch for holding (33b),
(34a) (34b) are capacitors (33a) (
Voltage that outputs the voltage held in 33b) as it is? The follower (35) is the voltage follower (34a) (34
an adder that takes the difference between the outputs of b);

TE is the output of the adder (35) and indicates a tracking error signal.

Next, the operation of the circuit shown in FIG. 4 will be explained. In FIG. 4, RF is a signal output from the heads (la) and (lb) in FIG. 1, and is a series of high-frequency waves as shown in FIG. 5(A). In the example of FIG. 5(A).

The magnetic tape (1) is attached to the rotating cylinder (1) in FIG.
3) shows an example in which the angle is less than 180 degrees, and in period TA, the head (1a) runs on the track A1 in FIG. 3 recorded by the head (1a), and the RF specific output is reproduced and output. , during period TB, the head (1b) runs on the track B1 in FIG. 3 recorded by the head (1b) to reproduce and output the RF ratio output. The RF multiplied signal amplified by the amplifier (14) is separated into a synchronization signal and a tracking signal by filters (15) and (23). FIGS. 5(B) and 6(A) show separated synchronization signals, and FIGS. 5(C) and 6(B) show tracking signals. In the example of FIGS. 5 and 6, the magnetic head (la)
(lb) shows the case where a head gap larger than the track width as shown in head gap H in FIG. 3 is used. In Fig. 3, when the head gap H moves on the track A1, at the beginning of the track, the track BO first
A part of the head gap traces the recorded part of the tracking signal f2 of track A1, and then sequentially traces the recorded part of the sync signal f1 of track A1, and then the recorded part of the tracking signal f of track B1. . The heads (t=) (tb) in Figure 1 are set at opposite azimuth angles so that data does not interfere with each other, but only the tracking signal f2 is set to a sufficiently low frequency so that there is no azimuth loss of information on adjacent tracks. It is. Of course, the synchronization signal should be set at a high frequency so as not to read adjacent tracks. Therefore, the synchronization signal separated by the filter (15) hardly appears in the period TB as shown in FIG. 5(B) due to azimuth loss, and the tracking signal does not appear in the period TA as shown in FIG. The crosstalk portion of the adjacent track BO1B1 appears in synchronization before and after , and the signal of the own track is output during the period TB.

The synchronizing signal shown in FIG. 6(A) is rectified by a rectifier circuit (16), and compared with a reference voltage vg by a comparator (17).
Output the route. The pulse generation circuit (19a) is shown in Fig. 6 (
A pulse is generated in synchronization with the rising edge of the pulse in C). This pulse is applied to the OR circuit (22).

Here, the input of the OR circuit (22) is at a low logic level, and the applied pulse is output as Pl in FIG. 6(D). Further, the output pulse of the comparator (17) is delayed by the delay circuit (18) and applied to the pulse generation circuit (19b), but this pulse generation circuit (19b) also generates a pulse in synchronization with the rising edge of the applied signal. This pulse is also applied to the OR circuit (22).

Here, the other input of the OR circuit (22) is at low logic and the applied pulse is output as P2 in FIG. 6(D). The time delay of the delay circuit (18) is equal to the time difference TD between pulses P1 and P2 in FIG. Further, the output of the pulse generation circuit (19a) is delayed by the delay circuit (20a) and applied to the pulse generation circuit (21a), but the pulse generation circuit (21a) outputs the sixth signal in synchronization with the rising edge of the applied signal. A pulse with a short time width as shown in Figure (E) is generated. Similarly, the output of the pulse generation circuit (19b) is also delayed by the delay circuit (20b), and the output of the pulse generation circuit (21a) is delayed by the delay circuit (20b).
) to generate a pulse with a short time width as shown in FIG. 6(F). The time delay of the delay circuit (20a) is equal to the time difference T□ between FIG. 6(D) and FIG. 6(E). Moreover, the time delay of the delay circuit (20a) is shown in FIGS. 6(D) and (F).
) is equal to the time difference T2.

On the other hand, FIG. 6 (B) extracted by the filter (23)
) is applied to a resistor (24), rectified by a diode (25), and charged to a capacitor (26). The switch (29) is a switch whose contacts are disconnected when it is in a high logic state and connected when it is in a low logic state.At this time, the switch (29) is in the on state and the contacts are connected, so the resistors (27) (28) ), capacitor (2
6) determines the discharge time constant. In addition, Fig. 6 (D
) is applied to the switch (29), the switch (29) is turned off and the contact is removed. The discharge time constant at this time is determined by the resistor (27) and capacitor (26). Its output is T3J in Figure 6'(G)
T4, and this output is applied to the voltage follower (30). The tracking signal output from the voltage follower (30) is applied to the switches (31) and (32). Here, the pulse shown in Figure 6(E) is applied to the switch (3).
1), the contacts of the switch (31) are connected and the capacitor (33a) is connected to the current voltage follower (3).
The battery is charged as indicated by SA in FIG. 6(G) so that the output voltage becomes 0). Similarly, when the pulse shown in FIG. 6(F) is applied to the switch (32), the voltage S shown in FIG. 6(G)
B is charged to the capacitor (33b). The voltage across the capacitors (33a) ('33b) is then applied to the switch (33).
1) It is held until a pulse is applied to (32). The delay time TD of the delay circuit (18) shown in FIG.
Pulse P2 is in section T of the tracking signal in FIG. 6(B).
If the voltage SB in FIG. 6(G) is set to be at the center of lt, the voltage SB in FIG. 6(G) will be held in the capacitor (33b) without error. In addition, the delay circuits (20a) (20b) shown in FIG.
) can be done without the delay times T1 and T2.

Therefore, due to the function of the sample pulse generation circuit (10), after the synchronization signal shown in FIG. 6(A) is output, the voltage follower (3
4a) The voltages SA and SR are output to the outputs of (34b), respectively, and the voltage VTEV of the output TE of the adder (35)
TR=sA-sB.

In Fig. 3, if the head gap H is the track BO
If the same amount appears on both track B1 and track B1, then the sixth
In the figure, SA and 88 are equal, then VTE=
O indicates a state where there is no tracking error. The relationship between the relative position between the head gap H and the track and the tracking error output voltage VTE is shown in Figure 7(a).
Shown in b). Figure 7(a) shows tracks BO, Al, B1
7 (
b) shows the relationship between the position of the center HC of the helad gap H and the tracking and error voltage VTE. To briefly explain Fig. 7, when HC is O as shown in Fig. 7(b), the tracking error is zero and ■τE = O is as described above, and when HC is in the range of Gh shown in Fig. 7, the tracking error is zero. The amount of head gap protrusion between BO and track B1 increases as one increases, while the other decreases by twice the change in one track.v
TE changes. If the center HC of the head gap deviates from the range Gh, for example, in the range GQ in FIG. 7, the head gap H will not reach track B1 at all and track B
vTE is determined only by the amount of overlap with O, and the change in the tracking error signal VTE with respect to the deviation of the HC from the center of the track A1 is 1/2 of the interval of Gh.

Further, when the head gap center HC moves away from the center of the track A1 and reaches the range GC in FIG. 7, the head gap H covers the entire track BO, so the tracking signal becomes constant.

In this way, the center H of track A1 and Herad gap H
With respect to the positional relationship with C, the tracking detection circuit of FIG. 4 has a tracking error voltage V as shown in FIG. 7(b).
Generates TE. This tracking error voltage vTE is added to the output of the speed control circuit (7) of the capstan motor (5) via an adder (8) as shown in FIG. 1, so that the tracking error signal vTEtil-vTE=0. The head gap H shown in FIG. 3 or FIG. 7(a) can be used to trace the track A1.

In addition, in FIG. 3, the area F where the synchronization signal f1 and the tracking signal f2 are recorded is, as is clear from the above explanation, an area F of an adjacent track and an area F of the track, where the head traces the track. The length must be long enough to overlap in time. In other words, the third
In the figure, F must be larger than the difference TG at the start of recording between tracks. However, in a device that records information by forming a helical track on a magnetic tape, the difference TG at the start of recording is usually extremely small compared to the track length of the track, and the area F is It does not require a large percentage of the total.

When recording an ATF signal as shown in Figure 3, the synchronization signal f
As mentioned above, it is possible to detect the tracking signal on the tracks A1 and A2 recorded in No. 1 and perform tracking control using the tracking error voltage VTE.
In the ATF signal shown in the figure, there is no synchronization signal in tracks BO1B1, B2, etc., and tracking errors cannot be detected. However, as shown in Figure 8, there are two ATFs in one track.
Areas F1 and F2 are provided, and the tracking signal f2 is recorded in F of the track in which the synchronization signal f1 is recorded in F□, and the F of the track in which the tracking signal f2 is recorded in Fl.
If the track pattern is such that synchronization signal f1 is recorded on track A1 and A2, tracks BO and B
1 and B2 as well, the tracking error voltage vTE can be detected and more accurate tracking control can be performed. In this case, the synchronization signal detection circuit (9
), detection circuit (11), tracking detection circuit (12)
does not need to be changed.

In the above explanation, the ATF signal area is set at the start of each track, but it goes without saying that the same effect can be achieved no matter where the ATF signal area is located on the track as long as it is at a fixed position on each track. stomach.

Furthermore, in the example shown in FIG. 2, the synchronization signal f□ is recorded in the same size area as the tracking signal f2, but the synchronization signal f1 is even recording start timing as compared to the tracking signal f
It is clear that the above-mentioned effects can be obtained by matching the recording start timing of No. 2, and the recording area of the synchronizing signal f1 may be smaller or larger than the tracking area f2.

Effects of the Invention As described above, the magnetic recording/reproducing device of the present invention is capable of performing stable tracking control without using a control head that tends to be mechanically unstable as in the conventional technology, and is capable of performing stable tracking control during tracking. It has the great feature that the area occupied by the A'TF region in can also be made small.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the main parts for explaining the tracking method of the magnetic recording/reproducing apparatus of the present invention, FIG. 2 is a diagram showing an example of tracks and tracking information areas on a magnetic tape, and FIG. 3 is a tracking information area. FIG. 4 is a block diagram showing an example of a synchronizing signal detection circuit, a sample pulse generation circuit, a detection circuit, and a tracking detection circuit used in the magnetic recording/reproducing apparatus of the present invention. FIGS. 6 and 7 are diagrams for explaining the operation waveform diagram and the output of tracking errors, and FIG. 8 is a diagram showing another example of tracking information area recording. (1a) (1b)... Rotating head, (13)...
・Magnetic tape, (BO) (Al) (Bl) (A2) (B
2)...Track, (F)...Tracking information area (ATF area), (9)...Synchronization signal detection circuit,
(10)...Sample pulse generation circuit (11)...
Detection circuit, (12)...Tracking detection circuit agent Yoshihiro Morimoto Figure 2 Figure 5 Shi-1-12 Figure 7 Figure δ

Claims (1)

[Claims] 1. A magnetic recording and reproducing device that records and reproduces information by forming helical tracks on a magnetic tape using a rotating head, and tracking information that records a fixed length of tracking information at a predetermined position from the starting end of each track. a synchronization signal detection circuit that provides an area, alternately records a tracking signal for tracking information detection and a synchronization signal for tracking information reading synchronization in the tracking information area, and detects the synchronization signal; and an output of the synchronization signal detection circuit. a sample pulse generation circuit that generates a pulse at , a detection circuit that inputs the tracking signal and is capable of changing a time constant with the output pulse of the sample pulse generation circuit, and an output pulse of the sample pulse generation circuit, A magnetic recording/reproducing apparatus comprising: a tracking detection circuit that samples and detects output information of the detection circuit; and configured to control running of the magnetic tape using an output signal of the tracking detection circuit.