JPH0444619A - Control signal generator for VTR dynamic tracking - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a V
The present invention relates to a control signal generator for dynamic tracking of TR.

[Conventional technology]

Generally, in a VTR, in order to obtain good reproduced images, it is important that the head traces the recording pattern of the tape during reproduction so as to obtain the maximum reproduction output. For this reason, various tracking control methods have been proposed in the past, but in recent years, so-called dynamic tracking, which allows more advanced tracking control, has been developed and improved with the aim of improving image quality during variable speed playback. are overlaid. In the dynamic tracking described above, the head is driven by a piezoelectric element to displace the head in the width direction of the tape, and the control voltage supplied to the piezoelectric element is generated by, for example, the configuration shown below.

In the configuration shown in FIG. 4, when the head switching pulse H3W is input to the microcomputer 21, the initial positions at which the heads 22 and 23 contact the tape (not shown) are determined by a clock generation circuit 29, which will be described later. The data is generated as initial position data based on the running direction and running speed of the tape. For example, when the output is switched to the head 22, the initial position data is supplied to the selected drive counter 24 and preset.

Further, the microcomputer 21 detects a tracking error from a change in the envelope of the reproduction signal taken out from the head 22 and amplified by the reproduction amplifier 26, and generates correction data according to the amount of error. This correction data is converted into an analog signal by the D/A converter in the microcomputer 21 and becomes a correction signal, which is sent to the adder 2.
7 is input.

On the other hand, the clock generation circuit 29 receives two types of FCs, pulse FC and -FC, which have the same shape but different phases, from a capstan motor (not shown). The clock generation circuit 29 determines the running direction of a tape (not shown) based on changes in the phase relationship and period of the FC pulse FGIFGz, detects the running speed of the tape, and sends these results to the microcomputer 21. Up clock UC & and down clock D ck are output according to the above results. Then, the drive counter 24 counts up or down from the initial position data preset as described above based on the up clock Uck or down clock Dck.

The count data output from the drive counter 24 is converted into an analog signal by a D/A converter (D/A in the figure) 30 to become a drive signal, which is input to an adder 27, where:
The correction signal and drive signal are added. The result of this addition is then amplified by the drive amplifier 32 and supplied as a control signal to the actuator 34 that drives the magnetic head 22. As a result, the magnetic head 22 is driven and displaced in the width direction of the tape according to the tape running speed, running direction, and amount of tracking error.

When the output is switched to the head 23, the drive counter 25, D/A converter (D/A in the figure) 31, adder 28, drive amplifier 33, and actuator 35 operate the head 23 in the same manner as above. Displace.

[Problem to be solved by the invention]

However, in the above-mentioned conventional technology, the circuits for generating the micro-drive signal and the correction signal are each configured separately, so the circuit size has to be increased. In addition, since the control signal is obtained by analog addition of the drive signal and the correction signal, errors due to D/A conversion are also added, and the control signal is
Signal errors tended to become large.

[Means to solve the problem]

In order to solve the above problems, the VTR dynamic tracking control signal generator according to the present invention generates initial position data that determines the initial position at which the head contacts the tape when the output of the magnetic head is switched. An initial position data generation means, a drive data generation means for generating drive data for driving the head by a certain amount, and a driving data generation means for detecting a dragging error from a reproduction signal and generating correction data for correcting the amount of displacement of the head according to the amount of error. A correction data generating means and a tape, with the generated data of the initial position data, drive data, or correction data as one addition input data, and the addition output data obtained from the previous addition as the other addition input data. control data generating means for sequentially adding data at timings corresponding to the running direction and running speed of the drive unit and using the updated addition output data as control data for determining the amount of head displacement; and converting the control data into analog to displace the head. It is characterized in that it includes a D/A conversion means for converting control signals.

[For production]

In the above configuration, when the initial position data of the initial position of the next head in contact with the tape is generated by the initial position data generating means at the time of head switching, this initial position data is added to the addition output data by the control data generating means. However, at this time, since there is no addition output data yet, the initial position data is output as is as the first addition output data. This addition output data is used as the other addition input tape, and is converted into an analog signal by a D/A conversion means as control data to become a control signal.

Subsequently, when drive data is generated by the drive data generation means, this drive data is added by the control data generation means to the added output data, that is, the initial position data obtained by the above addition, and updated as the next added output data. ,
New control data is generated. Further, when a tracking error occurs in the reproduced signal, the correction data generating means detects the tracking error based on changes in the envelope of the reproduced signal, etc., and generates correction data according to the amount of error. In this case as well, the control data generation means adds the correction data and the addition output data to generate further updated control data.

In addition, in the above configuration, since the control data is sequentially updated at a timing corresponding to one running direction and running speed of the tape, when the control data is converted into analog data by the D/A conversion means, the control data is updated in the running direction and running speed of the tape. This is a control signal whose level changes according to the

Therefore, according to the above configuration, control data is generated from the initial position data, drive data, and correction data,
This control data becomes a control signal after D/A conversion, so
Processing system is simplified.

Furthermore, since the control data is generated by digital processing, more accurate control signals can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 1, the VTR according to this embodiment includes a microcomputer (hereinafter referred to as microcomputer) 1, control data generating means 2 and 3, and a D/A converter ( D/A) 4・
5, and a clock generation circuit 6.

The microcomputer 1 includes an initial position data generating means 7, a drive data generating means 8, and a correction data generating means 9. The initial position data generating means 7 is the head 10/11.
When the output is switched, a control pulse CTL supplied from a control head (not shown) is used as a reference based on the running direction and running speed of the tape obtained by the clock generation circuit 6 as described later. Initial position data for determining the initial position at which the heads 10 and 11 come into contact with a tape (not shown) is generated at the appropriate timing. Further, the drive data generating means 8 is configured to generate drive data for displacing the heads 10 and 11 by a certain amount. This drive data can be changed on the program, and thereby the head 10/1
The drive amount of 1 can be controlled. Then, the correction data generating means 9 digitally performs envelope detection on the reproduction signal inputted from the heads 10 and 11 via the reproduction amplifier 12 to detect a racking error, and adjusts the output of the heads 10 and 11 according to the amount of error. Correction data for correcting the amount of displacement is generated.

The control data generating means 2 and 3 are each composed of an adder 13 and a latch 14, and an addition δ15 and a latch 16. Adders 13 and 15 use the above-mentioned initial position data, drive data, and correction data that are output data from microcomputer 1 as one addition input, and add output data obtained from the previous addition and held in latches 14 and 16. This is a circuit that performs addition using the other addition input data.

The latches 14 and 16 convert their outputs into rough clocks supplied from the clock generation circuit 6, and the adders 13 and 15 use ck.
This is a circuit that holds the added output data. In addition, the latches 14 and 16 are selected by output enable signals OE I 4 and OE supplied from the microcomputer 1, respectively.
This enables latching operation, holding the output at high impedance and pulling it down when not selected.

The D/A converters 4 and 5 as D/A converting means are circuits that convert the control data generated by the control data generating means 2 and 3 into analogs to generate control signals.

The clock generation circuit 6 is supplied with two FC pulses FC and -FC from a capstan motor (not shown). These FC pulses FC, FC.

has the same shape, and when the tape is running in normal playback mode, the FC
Pulse FC is in phase 90@ ahead of FG pulse FC. The clock generation circuit 6 is a FG pulse FC.
+ - The running direction of the tape is determined based on which of the FGz leads, and the FG pulses FC, -'
The tape running speed is detected from changes in the cycle of FC, and these results are sent to the microcomputer 1.

The clock generation circuit 6 also includes a latch clock LC whose frequency corresponds to the tape running direction and tape running speed.
k is supplied to the aforementioned latches 14 and 16.

The control signals are then supplied to actuators 19 and 20 via drive amplifiers 17 and 18. Drive amplifier 1
7 and 18, the actuators 19 and 20 are connected to the head 10 and
This circuit amplifies the control signal to an appropriate level that can drive the 11. The actuators 19 and 20 are driving means that drive the heads 10 and 11 in the tape width direction using control signals amplified by the drive amplifiers 17 and 18.

In the above configuration, when the head switching pulse H3W shown in FIG. 2(a) goes from low level (L in the figure) to high level (H in the figure) and the output is switched from the head 11 to the head 10, 14 has microcomputer 1
to the out enable signal OE1. shown in (b) of the same figure.
(L in the figure) is supplied, and the latch operation of the latch 14 becomes possible.

Further, in the microcomputer 1, the initial position data generating means 7 generates initial position data as output data as shown in FIG. Then, since the addition output data to be added from the latch 14 has not been output, this initial position data is inputted as is to the latch 14, and here, the latch clock from the clock generation circuit 6 is applied to Ck(
(shown in (d) of the same figure).

The initial position data held as described above is fed back to the input of the adder 130 as the first addition output data, and following the initial position data, the drive data generated by the drive data generation means 8 of the microcomputer 1 (( (C)), while a control signal of level 2 is output as control data via the D/A converter 4, as shown in (e) of the figure. Then, by supplying this control signal to the actuator 19 via the drive amplifier 17, the head 10 is driven and displaced to an initial position where it contacts the tape.

Further, the sum of the initial position data and drive data obtained by the above addition is determined by the latch 14 at the next latch clock Le.
k and is input to the adder 13 and the D/A converter 4 as in the previous case. While the drive data continues to be generated from the drive data generation means 8, the drive data is sequentially added to the addition output data at the timing of the latch clock Lck from the clock generation circuit 6, so that the control signal is As shown in (e), the level increases by Δ■. Thereby, the head 10 is driven according to the running direction and running speed of the tape, and is displaced by a constant amount determined by the level ΔV.

Subsequently, as shown in FIGS. 3(a) and 3(b), while the head switching pulse H3W maintains a high level and the out enable signals OE and 4 are being output, the correction data generation procedure is started. When a tracking error is detected by stage 9, correction data is generated from here.
As shown in (C) of the figure, the microcomputer 1 outputs this correction data and drive data together. Then, the above-mentioned data are added together with the previous addition output data in the adder 13, and held by the latch clock Lck shown in FIG. moreover,
The control signal obtained through the D/A converter 4 is shown in (e) in the same figure.
), the level vt corresponding to the correction data and the level ΔV corresponding to the drive data increase. As a result, the head 10 is driven and displaced by an amount corresponding to the level v2 corresponding to the amount of tracking error in addition to an amount corresponding to the level Δ■, as in the above case.

Through the series of operations described above, a servo loop is formed, and tracking control is quickly performed.

In the above operation description, the case where the head 10 is displaced has been described, but when the head 11 is also displaced, tracking control is performed by the control data generation means 3, the D/A converter 5, the drive amplifier 18, and the actuator 20. will be held.

Further, in this embodiment, since the drive data generated by the drive data generating means 8 can be changed, the heads 10 and 11 can be driven more precisely.

〔Effect of the invention〕

As described above, the VTR dynamic tracking control signal generator according to the present invention has an initial position data generating means for generating initial position data for determining the initial position at which the head contacts the tape when the output of the magnetic head is switched. a drive data generation means for generating drive data for driving the head by a certain amount; and a correction data generation means for detecting a tracking error from the reproduction signal and generating correction data for correcting the amount of displacement of the head according to the amount of error. Then, the generated data among the above initial position data, drive data, or correction data is used as one addition input data, and the addition output data obtained from the previous addition is used as the other addition input data, and the tape running direction and A control data generating means that performs addition sequentially at a timing according to the traveling speed and uses the updated addition output data as control data for determining the amount of head displacement, and converts the control data into analog to use as a control signal for displacing the head. This configuration includes a D/A conversion means.

As a result, control data is generated from the initial position data, drive data, and correction data, and this control data is
Since the signal becomes a control signal after /A conversion, the processing system is simplified and the circuit scale can be reduced compared to the conventional method. Furthermore, since the control data is generated by digital processing, more accurate control signals can be obtained, and tracking accuracy in dynamic tracking can be improved.

[Brief explanation of the drawing]

1 to 3 show one embodiment of the present invention. FIG. 1 is a block diagram showing the configuration of the main parts of a VTR including a dynamic tracking control signal generator. FIG. 2 is a time chart showing the operation of the dynamic tracking control signal generator at the time of head output switching. FIG. 3 is a time chart showing the operation of the dynamic tracking control signal generator when outputting from one head. FIG. 4 shows a conventional example, and is a block diagram showing the configuration of the main parts of a VTR including a dynamic tracking control signal generator. 2 and 3 are control data generation means, and 4 and 5 are D/A converters (
6 is a clock generation circuit, 7 is an initial position data generation means, 81 is a drive data generation means, 9 is a correction data generation means, and 10 and 11 are heads.

Claims (1)

[Claims] 1. Initial position data generating means for generating initial position data for determining the initial position at which the head contacts the tape when the output of the magnetic head is switched, and drive data for driving the head by a certain amount. a drive data generating means for detecting a tracking error from a reproduced signal and generating correction data for correcting the amount of displacement of the head according to the amount of error; The generated data is used as one addition input data, and the addition output data obtained from the previous addition is used as the other addition input data, and the additions are performed sequentially at timings according to the running direction and speed of the tape. The present invention includes a control data generation means that uses the updated addition output data as control data for determining the amount of head displacement, and a D/A conversion means that converts the control data into an analog signal and uses it as a control signal for displacing the head. A control signal generator for dynamic tracking of a VTR.