JPS62110657A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute recording and reproducing with high detecting sensitivity by adding reproduced pilot signals to switch capacitor filter constituting circuits of two BPF, comparing detected two output and sending out tracking error signals through an invertor circuit. CONSTITUTION:Reproduced pilot signals are led from an input terminal 31 to BPF 51, 52 and the clock signals of a clock generating circuit 53 are applied to circuits 51, 52 by the command of a command circuit 54, and the signals of frequency (f1, f2), (f3, f4) are sent to detection circuits 36, 37 by switch, capacitor, filter SCF constitution. The output is compared 38 and sent to an invertor circuit 55, and tracking error signals are outputted 41 from the circuit 55.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording/reproducing device such as a video tape recorder, and more particularly to a magnetic recording/reproducing device that performs tracking control using a pilot signal recorded with a rotary head. be.

2. Description of the Related Art In the past, especially in household magnetic recording and reproducing devices, two rotating heads with different azimuth angles were alternately scanned diagonally to the longitudinal direction of a magnetic tape to generate video signals without providing a guard band. A rotating head, helical scan, azimuth recording method is used for recording. Tracking control is performed so that the rotary head correctly scans the azimuthally recorded tracks on the magnetic tape during reproduction.

One of the tracking control methods is to alternately superimpose a four-frequency / There is a method of detecting and forming a tracking error signal to perform tracking control.

FIG. 2 shows a block diagram of a servo circuit during reproduction in a magnetic recording and reproducing apparatus using the tracking control method using the four-frequency pilot signal.

In Figure 2, the rotating head is directly connected to its shaft (
The output of a rotation information detector 2 that detects rotation information of the cylinder motor 1 (not shown) is input to a speed control circuit 3, and a speed system error signal corresponding to the rotation speed of the cylinder motor 1 is obtained.

In addition, a rotational phase detector 4 provided in the cylinder motor 1
The output of the head switch generating circuit 5 generates signals corresponding to the two rotating heads, and the output thereof is input to the phase control circuit 6, where the phase is compared with the signal from the reproduction reference signal generating circuit 7, and the output is input to the cylinder motor. A phase system error signal corresponding to the phase of 1 is obtained. The velocity system and phase system error signals obtained in this manner are inputted to the mixing circuit 8 to obtain a mixed error signal, and this mixed error signal is inputted to the motor 1 drive circuit 9 to control the rotation of the cylinder motor 1.

On the other hand, a capstan shaft that transports the magnetic tape by pressure contact with a pinch roller is directly connected to the shaft (not shown).
The output of a rotation information detector 12 that detects rotation information of the capstan motor 11 is input to a speed control circuit 13, and a speed system error signal corresponding to the rotation speed of the capstan motor 11 is obtained. In addition, a reproduced pilot signal is reproduced from the magnetic tape by the rotating head (not shown) and inputted to the tracking error detection circuit 15 via the input terminal 14.
6-6 fH from the 4-frequency pilot signal generation circuit 16 in synchronization with the signal from the reproduction reference signal generation circuit 7.
f2 ” 7-5 f H,,7' 3” 10.5
The signals of fH*f4=9.51H (here, fH is the frequency of the horizontal synchronization signal of the video signal) are fl, f2. f3. f4
．． The signals are input to the tracking error detection circuit 16 in the order of fl along with the output of the head switch creation circuit 5.

FIG. 3 shows a detailed block diagram of the tracking error detection circuit 15. In FIG. 3, the reproduced pilot signal is inputted from an input terminal 31 to a balanced modulation circuit 32, and the reproduced reference signal is inputted via an input terminal 33, balanced modulated, and balanced modulated by the balanced modulation circuit 32. The output of 32 is f
H resonance circuit 34 and 3fH resonance circuit 7. ': input to 7 s, fH acid component 3fH component is extracted, respectively detected by detection circuit 36, 37, and detected by detection circuit 3
The output of 6.37 is input to a comparison circuit 38, which compares the levels of the fH acid component and 3fH component, and compares the crosstalk levels of pilot signals from adjacent tracks. The output of the comparison circuit 38 is inputted to the inverter circuit 39, and the output of the head switch creation circuit 5 is inputted via the input terminal 4o. It is output as a tracking error signal.

The capstan speed system error signal and the tracking error signal are inputted to a mixing circuit 17 to obtain a mixed error signal, and this mixed error signal is inputted to a motor drive circuit 18 to control the rotation of the capstan motor 11. The video head is made to on-track the recording track pattern of the magnetic tape.

Problems to be Solved by the Invention In the tracking error detection circuit described above, the fH resonant circuit and the sfH resonant circuit each constitute an fH or 3fH resonant circuit by connecting a coil and a capacitor in parallel. In order to do this, it is necessary to adjust the inductance of each coil, and there is also the problem that the resonant frequency changes from fH or 3fH due to temperature dependence, and the detection gain changes. Therefore, there is a problem that a large difference occurs between the total sensitivity of the fH frequency component and the total sensitivity of the 3fH frequency component, making it impossible to perform accurate tracking control. Another problem is that the coil of the resonant circuit is easily influenced by external electric fields.

Means for Solving the Problems The present invention solves the above problems by converting the regenerated pilot signal into the first . Second. Third. Switch the bandpass filters (hereinafter referred to as B, P, and F) according to the fourth frequency.
The capacitor filter circuit (hereinafter referred to as SCF circuit) is composed of two circuits, and the clock frequency supplied to the SCF circuit is switched in time division to configure four BPFs, and the outputs of the two BPFs are each detected by a detection circuit. The tracking error signal is formed by performing detection and comparing the outputs of each detection circuit with a comparison circuit.

Operation The present invention can reduce variations in detection sensitivity of each frequency component by the above-described configuration.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the tracking error detection circuit of the present invention.

In FIG. 1, the regenerated pilot signal is input from the input terminal 31 to the BPF circuit 51 of fl or f2 and the BP of f3 or f4.
The signal is input to the F circuit 62. BPF circuits 51 and 52 are SC
It is composed of an F circuit, and the pass band of the BPF circuit can be selected by switching its clock frequency. The clock generation circuit 53 is activated by a command from the command circuit 54.
The clock frequency is sent to each BPF circuit 51, 52, and the pass band of each BPF circuit is determined.

For example, if the recording signal of the main track is 11, then both adjacent tracks are f4 and 12, so the BPF circuit 5
The passband of 1.52 informs the clock frequency to become the BPF circuit of f2 and f4. Similarly, the main track f2/B
PF passband 1・f3)+f3(f2・f4>, f4
The clock frequency is switched so that it becomes (fl·f3). The outputs of the BPF@paths 51 and 52 are each sent to the detection circuit 36.
．． 37, and the outputs of the detection circuits 36 and 37 are input to a comparison circuit 38, which compares the crosstalk levels of pilot signals from adjacent tracks. The output of the comparison circuit 38 is input to the inverter circuit 56, and when the main tracks f2 and f3 are to be reproduced according to the command from the command circuit 54, the inverter circuit 55 is outputted without inverting, and the main tracks f1 and f4 are reproduced. At this time, the inverter circuit 56 inverts and outputs the signal, and outputs it from the output terminal 41 as a tiger and king error signal.

Effects of the Invention According to the present invention, BPFs of (fl f2) and (f3/f4) can be configured by configuring the first BPF circuit and the second BPF circuit with SCF circuits and switching the clock frequency. It is possible to reduce the variation in the gain of detection sensitivity, and all the circuits can be integrated into C-MO31 step I.
Since it can be constructed from C, the temperature dependence is reduced, there is no need for adjustment, and since no coil is used, it has the advantage of not being affected by external electric fields.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a traversing error detection circuit used in a magnetic recording and reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of a servo circuit during reproduction of the same magnetic recording and reproducing apparatus, and FIG. FIG. 2 is a block diagram of a conventional tracking error detection circuit. 51 f or f2 BPF circuit, 52-f3 or f4 BPF circuit, 63... clock generation circuit, 6
4...Command circuit, 36.37...Detection circuit, 3
8... Comparison circuit, 55... Inverter circuit.

Claims (2)

[Claims] (1) A rotary head that scans diagonally on a magnetic tape, a signal generator that generates four types of pilot signals each having a different frequency, and a signal generator that superimposes the four types of pilot signals with an information signal by the rotary head and generates the information signal. a recording device for recording on a magnetic tape; a reproducing device for reproducing the information signal and the pilot signal recorded on the magnetic tape by the rotary head; a signal processing device that forms a tracking error signal corresponding to a playback level difference between recorded pilot signals; and a signal processing device that performs tracking control so that the rotary head correctly scans the main track of the magnetic tape in accordance with the tracking error signal. a tracking control device, and the signal processing device converts the regenerated pilot signal into a first, second, third,
Select two outputs from the first, second, third, and fourth band-pass filters that select the fourth frequency component, and the outputs of the first, second, third, and fourth band-pass filters. A magnetic recording/reproducing apparatus characterized in that it has first and second detection circuits that detect waves, respectively, and a comparison circuit that compares outputs of the first and second detection circuits. (2) The first and second band-pass filters and the third and fourth band-pass filters each include a switch capacitor.
2. The magnetic field converter according to claim 1, wherein the magnetic field filter is configured of a filter, and the clock frequency supplied to the switched capacitor filter is switched in a time-division manner so that the band-pass filter can be shared. Recording and playback device.