JPH04286750A - Tracking controller - Google Patents

Abstract

PURPOSE:To rapidly control tracking by switching the operating state of a tracking control means in accordance with the existence or not of information recorded in a recording medium. CONSTITUTION:An RF signal recorded in a magnetic tape 4 is reproduced by a reproducing head 2. An ATF error signal is detected from a pilot signal included in the reproduced RF signal by an ATF circuit 7. On the other hand, a recorded part or an unrecorded part is judged in accordance with the existence or not of the reproduced RF signal while reproducing by an envelope detector 11. As the result of the discrimination, when the reproducing head is on the recording part, a selector 13 is turned to an ATF bias memory 8 side, a bias value obtained by an operation is added to the ATF error signal and an ATF control signal is obtained. When the unrecorded part is reproduced, the selector 13 is turned to an ATF bias initial value memory 12 side and the ATF control signal is obtained by adding the initial value to the ATF signal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control device for controlling tracking of a reproducing head.

0002

[Prior Art] Conventionally, when reproducing a VTR that multiplexes a tracking control pilot signal with a recording signal,
A pilot signal obtained from the reproducing head is detected, a tracking error signal (ATF error signal) is formed in a tracking control (ATF) circuit, and the ATF error signal is further corrected by a bias value to perform tracking control.

FIG. 3 shows a conventionally known tracking control device for a VTR. Here, 1 is a rotating drum, 2 is a playback head, 3 is a head amplifier that amplifies the playback RF signal, 4 is a magnetic tape as a recording medium, and 5
is a capstan motor for conveying the magnetic tape 4,
6 is a speed control circuit that outputs a speed control signal to keep the speed of the capstan motor 5 constant, and 7 is a tracking control signal (ATF control signal) that separates the regenerated pilot signal to form an ATF error signal. AT that outputs
F circuit, 8 is an ATF bias memory which will be described later, 9 is an adder that adds the speed control signal and the ATF control signal and outputs a capstan control signal, 10 extracts the video signal and audio signal from the reproduced RF signal, and extracts the necessary This is a signal processing system that performs signal processing.

In the above configuration, the signal recorded on the magnetic tape 4 is reproduced by the reproduction head 2 attached to the circuit drum 1. The reproduced RF signal is amplified by the head amplifier 3 and sent to the signal processing system 10 and the ATF circuit 7. The ATF circuit 7 separates the pilot signal included in the reproduced RF signal, forms an ATF error signal from the pilot signal, and adds the bias value stored in the ATF bias memory 8 to create an ATF control signal. Further, the ATF bias for the next tracking control is calculated and stored in the ATF bias memory 8. On the other hand, using a capstan rotation frequency (CFG) signal generated by the rotation of the capstan motor 5, the speed control circuit 6 detects a speed error and generates a speed control signal. The adder 9 performs tracking control by adding the above-mentioned ATF control signal and speed control signal and feeding it back to the capstan motor 5 as a capstan control signal.

[0005]

[Problems to be Solved by the Invention] However, in the above conventional example, when a signal is continuously reproduced from a portion where no signal is recorded to a portion where a signal is recorded on the magnetic tape, the AT
Because the F bias value becomes unstable, it is not possible to supply an appropriate ATF bias value to the ATF circuit the moment the recorded portion begins to be played back, and as a result, it takes time for the bias value to reach an appropriate value. However, the drawback was that tracking control was delayed.

[0006] Accordingly, an object of the present invention is to provide a tracking control device that enables quick tracking control regardless of the presence or absence of recorded information.

[0007]

[Means for Solving the Problems] A tracking control device according to the present invention includes a determining means for determining whether a reproducing head is tracing a recorded portion or an unrecorded portion on a recording medium, and an output of the reproducing head. The tracking control means is provided with a tracking control means for outputting a tracking control signal based on the above, and a switching means for switching the operation mode of the tracking control means in response to the discrimination output of the discrimination means.

[0008]

According to the present invention, the operation mode of the tracking control means is switched depending on the presence or absence of information recorded on the recording medium, thereby eliminating delays in tracking control.

[0009]

[Embodiment] The embodiment described in detail below includes an envelope detector that detects the presence or absence of a recording signal, and a selector that switches between an ATF bias memory value and an ATF bias initial value close to an appropriate value and provides it to the ATF circuit. By providing this, when the magnetic tape is continuously played back from the unrecorded part to the recorded part, tracking can be quickly performed by selecting the initial ATF bias value and adding an appropriate ATF bias value during playback of the unrecorded part. It was made so that it could be taken.

Next, the above embodiment will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In this figure, 1 is a rotating drum, 2 is a playback head, 3 is a head amplifier, 4 is a magnetic tape, 5 is a capstan motor, 6 is a speed control circuit, 7 is an ATF circuit, 8
1 is an ATF bias memory, 9 is an adder, and 10 is a signal processing system, which performs the same functions as the conventional example shown in FIG.

11 is an envelope detector that determines the presence or absence of recorded information by detecting the presence or absence of an envelope of the reproduced RF signal; 12 is an ATF bias initial value memory;
Reference numeral 3 denotes a selector for selecting the outputs of the ATF bias memory 8 and the ATF bias initial value memory 12, and, as will be described later, performs a function unique to this embodiment.

Next, the operation of this embodiment will be explained.

During reproduction, the RF signal recorded on the magnetic tape 4 is reproduced by the reproduction head 2 attached to the rotating drum 1, and after being amplified by the head amplifier 3, it is sent to the signal processing system 10, the ATF circuit 7, and the envelope. The signal is sent to the detector 11.

The flowchart in FIG. 2 shows the processing procedure when the magnetic tape 4 is continuously reproduced from an unrecorded portion to a recorded portion.

The ATF circuit 7 shown in FIG. 1 detects an ATF error signal from a pilot signal included in a reproduced RF signal. On the other hand, in the envelope detector 11, the reproduced RF
Depending on the presence or absence of a signal, a recorded portion or an unrecorded portion is determined during playback. As a result of the determination, when the reproducing head 2 is located above the recording portion, the selector 13 is moved to the ATF bias memory 8 side, and the ATF control circuit 7
A bias value obtained by normal calculation is added to the error signal to obtain an ATF control signal. Further, the ATF bias for the next ATF control is calculated and stored in the ATF bias memory 8.

When reproducing an unrecorded portion, move the selector 13 to the ATF bias initial value memory 12 side (the initial value is close to the appropriate bias value), and
The F circuit 7 adds the initial value to the ATF error signal to obtain an ATF control signal. Furthermore, the bias value calculated from this initial value is stored in the memory 8.

Then, the speed control signal output from the speed control circuit 6 and the ATF control signal are added by an adder 9,
Obtain capstan control signal.

The above operation is carried out until the recorded part is reproduced, and when the recorded part starts to be reproduced, the selector 13 is set to ATF bias 8 (a value calculated from the initial value is stored in memory).
Switch to the side. With this, normal tracking control is performed thereafter.

[0020] In this way, while reproducing the unrecorded portion, the AT
By using a predetermined initial value as the F bias value, inaccuracies in the ATF bias value calculation can be removed, the ATF bias value can be set to an appropriate value more quickly, and the required tracking when starting playback of the recorded portion can be achieved. It can save time.

[0021]

As explained above, according to the present invention, by switching the operation mode of the tracking control means depending on the presence or absence of a reproduction signal (in the embodiment, a predetermined initial bias value is used), the tracking control means can be moved from an unrecorded portion of a recording medium. Even when a recorded portion is continuously reproduced, quick tracking control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure according to an embodiment of the present invention.

FIG. 3 is a block diagram of a conventionally known tracking system.

[Explanation of symbols]

1 Rotating drum 2 Play head 3 Head amplifier 4 Magnetic tape 5 Capstan motor 6 Speed control circuit 7 ATF control circuit 8 ATF bias memory 9 Adder 10 Signal processing system 11 Envelope detector 12 ATF bias initial value memory 13 Selector

Claims (2)

[Claims] 1. Discrimination means for determining whether a playback head is tracing a recorded portion or an unrecorded portion on a recording medium; and tracking control means for outputting a tracking control signal based on the output of the playback head. ,
A tracking control device comprising: switching means for switching the operation mode of the tracking control means in response to the discrimination output of the discrimination means. [Claim 2] In Claim 1, the early switching means comprises:
A tracking control device characterized in that a tracking control bias value is set to a predetermined initial value when the reproducing head is tracing the unrecorded portion.