JPS6131545B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to information recording and reproducing technology, and more particularly to a method for detecting the recording format of a magnetic tape commonly used as an external storage medium for information processing devices.

Traditionally, as a recording format on magnetic tape media
The NRZI method, PE method, GCR method, etc. have been standardized. Furthermore, when one byte of information is written in parallel on a magnetic tape, the standard number of tracks has been 7 or 9 depending on each recording format. Therefore, when reading information from a magnetic tape on which information is recorded, it is necessary to correctly recognize the recording format. Conventionally, when reading a magnetic tape recorded on 9 tracks, a magnetic tape start marker (hereinafter referred to as BOT) is used.
A recording density indicator signal (hereinafter referred to as
It's called ID burst. ) are recorded. By detecting this, playback devices are standardized so that they can determine in what format the recording was made.

Conventionally, the phase synchronization method is often used as a method for recognizing ID bursts, but this method is controlled to set the phase mode that corresponds to one ID burst, so it is difficult to recognize multiple ID bursts at the same time. Can not do it. Also, magnetic tape is easily affected by dust, scratches, etc.
If the part where the ID burst is recorded is scratched,
If affected by garbage, ID bursts will not be recognized correctly. In addition, as new recording densities and formats are developed in the future, it will be necessary to develop ID bursts, and in such cases, conventional methods are not necessarily sufficient.

The present invention was made against this background.
It is less susceptible to tape scratches, dirt, etc., and can recognize multiple ID bursts at the same time.
Another purpose is to provide an ID burst detection method with a large degree of freedom even for new recording formats.

In the present invention, the entire area in which ID bursts are recorded is divided into a plurality of areas, one of a plurality of recording densities is sequentially set for each of the areas, and recording is performed by alternately switching these densities. Matches the ID burst part, and if there is a match,
It is characterized in that the recording density or recording format of the data portion corresponding to the ID burst is the recording format of the tape.

Next, the present invention will be explained in detail based on examples. FIG. 1 is a diagram showing the positional relationship of tape tracks in an ID burst section recorded using the PE (Phase-Encoding) method.

FIG. 2 is a diagram showing the positional relationship of tape tracks in an ID burst section recorded using the GCR (Group Coded Recording) method. In Figure 1, 1
is magnetic tape medium, 2 is ID burst, 3 is
BOT and 4 indicate the data section, respectively. The left side of the drawing is the starting end of the magnetic tape. PE method ID burst 2 has 1600Fci (per inch) on the 4th track.
(1600 magnetization reversals), and the recording start position and recording length are also standardized. The data section 4 is recorded on each track at a maximum recording density of 3200Fci.

On the other hand, in the GCR system shown in FIG. 2, 5 is an ARA burst and 6 is an ARA/ID burst. Others are designated by the same reference numerals as in FIG.
GCR method ID burst 2 is on the 6th track
3014Fci, and the recording start position and recording length are standardized. ARA burst 5 and ARA/ID burst 6 are bursts specific to the GCR method, and are used for setting read amplification gain during reading, and are not used for recording density recognition.
The data portion 4 of the GCR method is recorded at a maximum recording density of 9042Fci.

FIG. 3 is a configuration diagram of the phase synchronization circuit of the device according to the embodiment of the present invention. A read signal from a magnetic head is connected to a terminal 11, and a synchronization detection signal is sent to a terminal 12. The signal at terminal 11 is sent to synchronization detection circuit 13.
and one input of the phase detection circuit 14, respectively. The phase difference output of the phase detection circuit 14 is led to an integration circuit 15, and its DC signal output is led to a control input of a voltage controlled oscillator 16. The output of this oscillator 16 is connected to the other input of the synchronization detection circuit 13 and the phase detection circuit 14. The voltage controlled oscillator 16 also includes a control circuit 1
A setting mode switching signal is connected from 7. This control circuit 17 is preferably constructed from a microprocessor.

The phase synchronization circuit shown in FIG. 3 provides an output signal at terminal 12 when the clock frequency appearing in the read signal at terminal 11 is synchronized with the self-oscillating output clock frequency of voltage controlled oscillator 16. When a signal is input to terminal 11, voltage controlled oscillator 1
6 is controlled by a phase detection circuit 14 and an integration circuit 15 so that it is synchronized with this signal input.

FIGS. 4 to 6 are diagrams showing control of self-oscillation mode in the ID burst section. That is,
FIG. 4 shows a conventional control mode. According to the flow of ID bursts on the magnetic tape, the voltage controlled oscillator 16 shown in FIG. 3 is sequentially set to two modes.
For example, if the settings are first 1600Fci and then 3014Fci, the circuit shown in FIG. 3 will be synchronized in either mode, and the recorded format can be determined.

FIG. 5 shows the control mode of the embodiment of the present invention. That is, the control circuit 17 alternately and repeatedly switches the oscillation mode of the voltage controlled oscillator 16 as shown in FIG. 5, and when synchronization is achieved,
Determine the recorded format.

According to such control, synchronization can normally be achieved using either of the steps shown in FIG.

Figure 6 shows a case where the ID burst section 2 of the magnetic tape has scratches shown by diagonal lines.
, , synchronization can be achieved for the first time.
When a magnetic tape with such flaws is used in the conventional method (FIG. 4), it becomes undetectable if it is recorded at 1600 Fci.

Furthermore, by controlling as in the present invention, even if systems other than 1600Fci and 3014Fci are introduced as shown in this example, they can be easily configured to alternately switch between them, providing a high degree of freedom. method is obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams showing examples of information recording formats at the beginning of the tape. FIG. 3 is a diagram showing the main circuit configuration of an embodiment of the present invention. Figures 4 to 6 are diagrams showing control of self-oscillation mode, where Figure 4 is a conventional example, Figure 5 is an example of the present invention, and Figure 5 is an example of the present invention with scratches on the tape. Each is shown below. 1...Magnetic tape medium, 2...ID burst,
3...BOT, 4...Data section, 5...ARA burst, 6...ARA/ID burst, 11, 12...
...Terminal, 13...Synchronization detection circuit, 14...Phase detection circuit, 15...Integrator circuit, 16...Voltage controlled oscillator, 17...Control circuit.

Claims (1)

[Scope of Claims] 1. Means for detecting, by one magnetic head, a recording density indicator signal for identifying the type of recording format of information recorded on a magnetic tape at the starting edge of the magnetic tape, and the phase of the detected signal. a phase synchronization circuit for synchronization; and a means for switching the self-oscillation mode of the phase synchronization circuit to a plurality of modes, and a means for switching the self-oscillation mode of the phase synchronization circuit to a self-oscillation mode when the phase synchronization is broken. In a magnetic tape recording format detection method in which the corresponding recording format is the type of recording format recorded on the magnetic tape, the phase synchronization circuit detects the recording density indicator signal portion at the beginning of the magnetic tape by the switching means. A magnetic tape recording format detection method characterized by repeatedly switching its self-oscillation mode within a single reading time.