JPH0419853A - Digital data reproducing device - Google Patents

Abstract

PURPOSE:To satisfactorily detect a tracking error signal by converting a regenerative signal from a recording medium into a digital data, detecting a recording data from this digital data and detecting the tracking error signal as well. CONSTITUTION:After the regenerative signal from the recording medium 2 is converted into the digital data by an analog/digital converting circuit 4, the recording data is detected from this digital data by a digital data detecting circuit 6 while the tracking error is detected by a tracking error detecting circuit 11. By this method, the tracking error detecting circuit 11 can be constitutive as a digital signal processing circuit, where the tracking error signal can be detected with high accuracy owing to this digital signal processing, while the circuit constitution is simplified without needing a conversion circuit for converting a data of the tracking error detecting circuit 11 into its digital data.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a digital data reproducing device suitable for application to, for example, a digital VTR (video tape recorder).

[Summary of the Invention] The present invention provides a digital data reproducing device suitable for use in, for example, a digital VTR, in which a reproduced signal from a recording medium is converted into digital data by a digital-to-analog conversion circuit, and then recorded from this digital data. The tracking error signal is detected at the same time as the data, so that the tracking error signal can be detected satisfactorily.

(Prior art) Video signals and audio signals are recorded on a magnetic tape by forming one diagonal track for each unit time using a helical scan type rotary head device. It has been put into practical use to digitize audio signals and record and reproduce them. This is because digitalization allows high-quality recording and playback.

In this case, tracking control to ensure that the rotating head correctly scans the recording track during playback is conventionally performed by reproducing control signals recorded at one end of the tape in the width direction using a fixed magnetic head. This is normally done by making sure that this reproduction control signal and the rotational phase of the magnetic head have a constant positional relationship.

However, this method requires a dedicated fixed magnetic head for tracking control.

Providing such a fixed magnetic head is inconvenient when it is desired to miniaturize the recording and reciprocating device due to the location of its installation.

Therefore, the applicant previously proposed a method of controlling the tracking of a rotary head by using only the reproduction output of the rotary head for reproduction without using this fixed head (
(Japanese Unexamined Patent Publication No. 59-112406, etc.) This method is based on the fact that digital signals can easily be compressed and expanded on the time axis, and therefore there is no need to record and reproduce signals continuously in time, as with analog signals. Therefore, this method was developed with an eye to the fact that it is possible to easily record this digital signal and a separate signal by dividing the area into one track.

In other words, when a digital signal is compressed on the time axis and recorded by diagonally forming tracks on a recording medium using multiple rotating heads without forming a guard band, the digital signal is recorded in the longitudinal direction of each track. A plurality of tracking pilot signals are recorded independently as areas, and during playback, the recording track is scanned by a rotating head whose scanning width is wider than the track width, and the rotating head receives pilot signals from tracks on both sides of the track being scanned. The tracking of the rotary head is controlled by the playback output.

Here, an example of a track pattern of a digital audio tape recorder (DAT) that records digital audio signals is shown. This track pattern is as shown in Figure 2 (180' apart on the rotating head drum (1)). The magnetic tape (2) is formed by 2f[lil's magnetic hands H,,) (, which are arranged at different azimuth angles, and the magnetic tape (2) has a 90-degree angle on the circumferential surface of the rotating head drum (1). Can be wrapped more than °.

The pattern of tracks formed at an angle on the magnetic tape (2) is as shown in FIG.
Each track TaTb, Tc, Td,
Tracking areas TA are provided near the starting and ending ends of Ta, Tb, . . . , respectively.

TA2 is provided, and this tracking area TA,
, TA, has a pilot signal P and synchronization signals S, , S2 recorded in a predetermined state.

That is, the magnetic head HA of one azimuth (A azimuth)
A pilot signal P and a synchronizing signal Sl are recorded in the tracking areas TA, TA2 of the tracks Ta and Tc formed by the tracks Tb and Td formed by the magnetic head HB of the other azimuth (B azimuth). A pilot signal P and a synchronization signal S2 are recorded in the tracking areas TA and TA2. Then, the pilot signal P is recorded at one adjacent location (track) of the recording location of the synchronization signal S1 or S2 of each track, and the pilot signal P is recorded at a location slightly shifted from the adjacent track on the opposite side. The pattern is such that it is recorded. In this case, the pilot signal P is a relatively low frequency signal with little azimuth loss, and the synchronization signals S, , S, are higher frequency signals than this pilot signal P.

A data area D is provided in the center of each track Ta to Td, and digital data divided into blocks in a predetermined format is recorded in this data area D.

When each track formed in this way is reproduced by the magnetic head H1, He, for example, the magnetic head H1, He
When A detects the synchronization signal S1 recorded on track Ta or Tc, it detects the crosstalk amount of the pilot signal P recorded on one adjacent track Tb or Td, and also detects this synchronization signal S. After a predetermined time from the timing, the amount of crosstalk of the pilot signal P recorded on the other adjacent track Td or Tb is detected.

By doing so, the amount of tracking/knocking deviation of the magnetic head HA can be determined based on the amount of crosstalk of pilot signals from adjacent trunks.

That is, when the amount of crosstalk between the pilot signals P on both adjacent tracks is equal, the magnetic head HA is accurately tracing the center of the track Ta or Tc. Then, the identified tiger 1. Good tracking control is performed by controlling the servo circuit of a tape running capstan motor (not shown) in accordance with the amount of king deviation. Tracking control for the tracks Tb and Td is similarly performed when the magnetic head H3 detects the synchronization signal S2 recorded on the track Tb or Td and after a predetermined time, the pilot signal P from the adjacent tracks Ta and Tc is detected.
This is done by detecting the amount of crosstalk.

Here, a circuit for detecting this pilot signal P during reproduction is shown in FIG. 4. The signal reproduced from the magnetic tape (2) by the magnetic heads HA and H6 is passed through a preamplifier (3) to an analog-to-digital conversion circuit. (4) and converts it into digital data according to the reproduction signal level. The digital data output from the analog-to-digital conversion circuit (4) is equalized by a digital equalization circuit (5) and then supplied to a digital data detection circuit (6).

The digital data detection circuit (6) detects video signal data from the reproduced digital data, and supplies the detected video signal data to the digital video signal output terminal.

A tracking error detection circuit (8) is provided as a circuit for detecting the pilot signal P, and the reproduction signal output from the preamplifier (3) is supplied to this tracking error detection circuit (8). Then, the tracking error detection circuit (8) detects the amount of crosstalk of the pilot signal P, and outputs the detection level of this amount of crosstalk as a tracking error voltage. Then, this tracking error voltage is converted to an analog-to-digital conversion circuit (9
) as digital tracking error data, and this tracking error data is supplied to the output terminal (10).

Then, the signal is supplied from this output terminal (10) to a servo system control circuit (microcomputer configuration) that controls tape running, and tracking control is performed based on the tracking error data.

[Problems to be Solved by the Invention] By the way, the tracking error detection circuit (8) that detects the tracking error voltage needs to accurately detect the amount of crosstalk of the pilot signal P from the adjacent trunk. If the crosstalk amount detected by the tracking error detection circuit (8) is not accurate, tracking control based on the tracking error data will not be performed properly, and the magnetic head will not be able to accurately trace each track. It's gone. Here, in the conventional tracking error detection circuit, it is difficult to adjust the tracking error detection circuit so that accurate detection can be performed at all times because of the temperature characteristics and variations in the elements constituting the circuit.

An object of the present invention is to enable accurate detection of a tracking error signal of a reproducing apparatus that performs tracking control as described above.

[Means for Solving the Problems] The present invention provides a digital data reproducing apparatus for reproducing digital data recorded on a trunk formed on a recording medium (2), as shown in FIG. 2
) to the digital-to-analog conversion circuit (4).
), the recorded data is detected from the digital data by a digital data detection circuit (6), and a tracking error signal is detected by a tracking error detection circuit (11).

[Function] By doing this, the tracking error detection circuit can be configured as a circuit that performs digital signal processing, and the tracking error detection circuit can be configured as a circuit that performs digital signal processing. There is no need for a conversion circuit to convert the output into digital data, simplifying the circuit configuration.

(Embodiment) An embodiment of the present invention will be described below with reference to Fig. 1. In Fig. 1, parts corresponding to Figs. 2 to 4 are denoted by the same reference numerals. Detailed explanation will be omitted.

This example shows an example in which the present invention is applied to a digital VTR that reproduces a digitalized video signal, and the overall configuration is shown in FIG. In this example, the signal reproduced from the magnetic tape (2) by the magnetic heads HA and Ha attached to the rotating head drum is supplied to the analog-to-digital conversion circuit (4) via the preamplifier (3). - The reproduced digital data output from the digital conversion circuit (4) is supplied to the digital equalization circuit (5) side and also to the tracking error detection circuit (11). This tracking error detection circuit (11) is a circuit that performs digital signal processing, detects the amount of crosstalk of the pilot signal included in the reproduced digital data, creates tracking error data, and sends this digital tracking error data to the output terminal (10).
) to a servo system control circuit (not shown) that controls tape running.

The other parts are constructed in the same manner as the conventional reproducing apparatus shown in FIG.

By configuring the digital VTR of this example in this way,
Tracking error data is detected based on the reproduced digital data output by the analog-to-digital conversion circuit (4). Therefore, the tracking error detection circuit (11)
The crosstalk amount of the pilot signal included in the reproduced digital data is detected by digital signal processing, tracking error data is created based on this detected value, and highly accurate tracking error data can be detected by digital signal processing. Good tracking control can be performed. In other words, by detecting tracking error data using digital signal processing, the detection accuracy does not deteriorate due to temperature characteristics or variations in the elements that make up the circuit that detects the amount of crosstalk of the pilot signal, and it can always be adjusted with simple adjustments. Highly accurate tracking error data can be detected.

Further, by performing digital signal processing, the tracking error detection circuit (11) can be easily integrated into an integrated circuit. Furthermore, since the tracking error data output by the tracking error detection circuit (11) has already been converted into digital data, the tracking error detection circuit (11) has already converted into digital data.
1) There is no need for a digital-to-analog conversion circuit to convert the output into digital data, simplifying the circuit configuration.

In the above-described embodiment, an example was shown in which the present invention was applied to a digital VTR for reproducing digital video signals, but the present invention may also be applied to a reproducing apparatus for recording media on which other digital data is recorded.

Furthermore, it goes without saying that the present invention is not limited to the above-mentioned embodiments, and can take various other configurations.

〔Effect of the invention〕

According to the present invention, tracking error data can be detected with high accuracy through digital signal processing, and good tracking control can be performed, and a conversion circuit for converting tracking error voltage into digital data is not required, making the circuit configuration simple. .

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an example of the present invention, FIG. 2 is a configuration diagram showing an example of a drum configuration, FIG. 3 is an explanatory diagram showing an example of a track pattern on a magnetic tape, and FIG. 4 is a conventional diagram. FIG. 2 is a configuration diagram showing the circuit configuration of FIG. (2) is a magnetic tape, (4) is a digital-to-analog conversion circuit, and (11) is a tracking error detection circuit. Agent Hidemori Matsukuma

Claims (1)

[Claims] A digital data reproducing device that reproduces digital data recorded on tracks formed on a predetermined recording medium, wherein a reproduced signal from the recording medium is converted into digital data by a digital-to-analog conversion circuit. 1. A digital data reproducing device characterized in that the recording data is detected from the digital data and a tracking error signal is also detected.