JPS6390008A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To reproduce faithfully data by controlling a prescribed period in which data are recorded on a magnetic recording medium as a digital value and a read signal is extracted and applied to a signal processing means in accordance with a change in the traveling speed of the recording medium. CONSTITUTION:A magnetic head 12 reads out data recorded on a magnetic tape 11 as a digital value and supplies the data converted into an electrical signal to a head amplifier 13. An amplified and waveform-equalized signal is applied to an envelope detecting circuit 14 and a reproduced signal PLL circuit 16. The output of the circuit 14 is applied to the circuit 16 and a pulse generating circuit 19 generates a repeated pulse signal having a fixed period and applies the signal to the circuit 16. The circuit 16 synchronizes the signal applied from the amplifier 13 with the pulse signal and outputs a signal to a signal processing circuit 17 only for a period in which the output is applied from the circuit to the circuit 16. A mode switching circuit 15 applies a prescribed signal to the circuit 14 in accordance with a change in the traveling speed of the tape 11. Thus, the data can be faithfully reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention samples an analog signal at a specific frequency, converts it into a digital signal, records it on a magnetic tape, or reads the recorded signal and restores it to an analog signal. The present invention relates to a magnetic recording/reproducing device which performs reproduction.

BACKGROUND ART Conventionally, in this type of magnetic recording/playback device,
A magnetic tape, which is a recording medium, runs at a predetermined speed while sliding on a part of the outer peripheral surface of a rotating drum on which a magnetic head is attached.The axis of the rotating drum is tilted at a predetermined angle with the running direction of the magnetic tape. A so-called azimuth recording method is used in which the recording medium is rotated around an axis.

FIG. 5 is a diagram showing the state of sliding contact between the magnetic tape 1 and the magnetic heads 2a, 2b. The magnetic tape 1 runs in the direction of arrow A in FIG. 5, and the magnetic heads 2a and 2b slide in contact with the magnetic tape 1 while moving in the direction of arrow B. And the data is recorded without any gaps on the magnetic tape 1! Recorded in i-area P.

Further, reproduction is performed by an operation similar to the recording operation described above.

During reproduction, in the so-called normal reproduction mode, the magnetic heads 2a and 2b move along the virtual lines Ji1. ．．
l) Slide the magnetic tape 1-F as shown in 2. Further, the magnetic heads 2a and 2b move as shown by imaginary lines 73 and 74 in FIG. 5 in a so-called rewind mode, and as shown by imaginary lines 5 and 7 in a fast forward mode. For example, in the rewind mode, the magnetic head 2a slides over two areas, the recording area P1 and the recording area P2, so the reproduced signal includes two different types of signals. Further, in the fast forward mode, since the recording area P3 is slid into contact with the recording area P3 in an inclined state, the output becomes small in the upper side of FIG. 5, making it difficult to reproduce the signal. As described above, in the fast forward mode or the rewind mode, there is a problem in that it is difficult to reproduce faithfully the original data that was recorded.

Problems to be Solved by the Invention, α An object of the present invention is to solve the above-mentioned problems and to reproduce recorded data as faithfully as possible even when the running speed of a magnetic recording medium changes. An object of the present invention is to provide a magnetic recording/reproducing device that can perform the following functions.

Means for Solving the Problems The present invention provides a magnetic recording/reproducing apparatus for recording data in digital values on a magnetic recording medium that is driven to run in a predetermined direction or the opposite direction, or for reproducing recorded data. , reading means for reading data recorded on a magnetic recording medium; signal extracting means for outputting the signal only for a predetermined period; signal extracting means for outputting the signal only for a predetermined period; and a means for controlling the length of the period during which the signal extraction means outputs the signal according to a change in the running speed of the magnetic recording medium. Please use a recording/playback device.

According to the present invention, data recorded on a magnetic recording medium is read by the reading means, and the output signal of the reading means is
The signal is extracted and output only during a predetermined period by the signal extracting means, and is provided to the signal processing means. The predetermined period is controlled by a control means in accordance with changes in the running speed of the magnetic recording medium.

Embodiment FIG. 1 is a block diagram showing the electrical configuration of a magnetic recording/reproducing device (hereinafter abbreviated as the present device) 10 according to an embodiment of the present invention. This device 10 includes a magnetic head 12 and a head amplifier 13 as reading means, an envelope detection circuit 14 and a mode switching circuit 15 as control means, and a reproduced signal PLL (PI) as signal extraction means.
+ase L oak Loop) circuit 16, a signal processing circuit 17 as a signal processing means, and a digital/analog (hereinafter abbreviated as D/A) converter 18.

The magnetic head 12 slides on the data recording surface of the magnetic tape 11 on which data is recorded, reads the data, and converts it into an electrical signal. The data converted to electrical signals is
Figure line! As shown at 1, the signal is applied to the head amplifier 13. The head amplifier 13 amplifies the input signal and performs waveform equalization processing. The waveform equalization process will be explained below.

For example, when data is transmitted and recorded on a recording medium, the frequency band of the recording medium is finite, and the amplitude spectrum of any signal waveform is infinite. A waveform different from the data waveform is reproduced. This is called code amount interference.

The processing performed to reduce this code amount interference as much as possible is waveform equalization processing.

The signal that has been processed as described above is used as a signal that has been processed as described above. As shown in No. 3, the signal is applied to the envelope detection circuit 14 and the reproduced signal PLL circuit 16. The envelope detection circuit 14 performs envelope detection of the input signal. The output of the envelope detection circuit 14 is the first
Line J in the diagram! 4, it is applied to the PLL circuit 16 for reproduction signals.

A pulse generating circuit 19 is connected to the reproduced signal PLL circuit 16, and the pulse generating circuit 19 generates a repetitive pulse signal having a constant period, and generates a repetitive pulse signal as shown in line No. 5 in FIG.
As shown, the pulse signal is applied to the reproduced signal PLL circuit 16. The reproduced signal PLL circuit 16 synchronizes the signal provided from the head amplifier 13 with the pulse signal, and outputs each of the signals as shown by the line grooves in FIG. 1 only during the period when the envelope detection circuit 14 provides the output. Output.

The signal processing circuit 17 receives the output from the reproduced signal PLL circuit 16, performs signal processing such as data decoding processing, dinterleave processing, and interpolation processing, and further performs signal processing such as data decoding processing, dinterleave processing, and interpolation processing. D/A converter, 1 as shown at 7
8, and D/A conversion processing is performed.

The mode switching circuit 15 outputs a predetermined signal in response to a change in the running speed of the magnetic tape 11, that is, a change in the normal playback mode, fast forward mode, or rewind mode, and outputs a predetermined signal according to the change in the running speed of the magnetic tape 11, and outputs a predetermined signal according to the change in the running speed of the magnetic tape 11. As shown in 8, the output is sent to the envelope detection circuit 1.
Give to 4. The operation of the device 10 having the above configuration will be described below.

FIG. 2 is a diagram showing signal waveforms in the normal playback mode of the device 10. FIG. 2(1) shows the output waveform H1 from the head amplifier 13, and FIG. 2(2) shows the time axis of FIG. 2(1) reduced and simplified. Output waveform H
1 is a waveform that has a fixed period T1 and outputs a signal for a fixed period T2.

FIG. 3 is a diagram showing signal waveforms of the present device 10 in the rewind mode, and FIG. 4 is a diagram of signal waveforms of the present device 10 in the fast forward mode. Figure 3 (2) is shown in Figure 3 (
The time axis of FIG. 4(1) is reduced and simplified, and FIG. 4(2) is a reduced and simplified time axis of FIG. 4(1). When reproducing data using the present device 10, in the normal reproduction mode, the magnetic head 12 slides over one data recording area of the magnetic tape 11, as explained in the background art section. As shown in FIG. 2, normal data reproduction is performed.

In the rewind mode, since the two recording areas are in sliding contact, the output signal H2 of the head amplifier 13 is
The waveforms are as shown in FIG. 3(1) and FIG. 3(2). The signals in period T3 and period T4 in FIG. 3 are signals in two mutually adjacent regions.

Switching between the normal playback mode and the rewind mode is performed by a changeover switch (not shown). Mode switching circuit 1
5 is a so-called low level output in the normal reproduction mode, and a high level output in the rewind mode, depending on the switching mode of the changeover switch.

The envelope detection circuit 14 outputs a signal as shown in FIG. 2 (3) when the output of the mode switching circuit 15 is low level, and when it is high level, it outputs a signal as shown in FIG. 172 of period T2 in case of mode
A signal is output only during period T5.

The output playback signal of the head amplifier 13 in the rewind mode as shown in FIGS. 3(1) and 3(2) is synchronized with the pulse signal generated by the pulse generation circuit 19 in the playback signal PLL circuit 16. is output only during the period T5, subjected to signal processing by the signal processing circuit 17, and then outputted from the D/A
The converter 18 performs D/A conversion to obtain an analog signal. This analog signal is given to other processing devices from the output terminal 20. In this way, in one playback period (indicated by the reference mark -T1 in Figure 2), only data in one recording area is played back, making it possible to play back data with greater fidelity and closer to the original recorded data. Become.

Even in the fast forward mode, the output of the mode switching circuit 15 is at a high level, as in the rewind mode, and the envelope detection circuit 14 outputs a signal only during the period T3, as shown in Figure 4 (3).

Therefore, among the three output signals H of the head amplifier 13 as shown in FIG. 4(1) and FIG. 4(2), the period T
3 is output from the playback signal PLL circuit 16. Then, the output signal is processed by the signal processing circuit 17, and D/A conversion is performed by the D/A converter 18 to obtain an analog signal, which is supplied from the output terminal 20 to another processing device. In this way, the portion 21 where the signal level of the output signal H3 has decreased is deleted, allowing error-free signal processing and data reproduction with high fidelity.

Effects As described above, according to the present invention, recorded data can be reproduced as faithfully as possible even when the traveling speed of the magnetic recording medium changes.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of a magnetic recording/reproducing apparatus 10 according to an embodiment of the present invention, FIG. 2 is a diagram showing signal waveforms of the magnetic recording/reproducing apparatus 10 in normal reproduction mode, and FIG.
The figure shows a magnetic recording/reproducing device 10 in rewind mode.
FIG. 4 is a diagram showing the signal waveform of the magnetic recording/reproducing apparatus 10 in the fast forward mode, and FIG. 5 is a diagram showing the state of sliding contact between the magnetic tape 1 and the magnetic heads 2a, 2b. be. 10... Magnetic recording/reproducing device, 11... Magnetic tape, 12... Magnetic head, 13... Head amplifier, 1
4... Envelope detection circuit, 15... Mode switching circuit, 16... PLL circuit for reproduced signal, 17... Signal processing circuit, 18... D/A converter representative patent attorney Keiichi Shisan reports

Claims (1)

[Scope of Claims] A magnetic recording/reproducing device that records data in digital values on a magnetic recording medium that is driven to travel in a predetermined direction or the opposite direction, or that reproduces recorded data, comprising: recording on a magnetic recording medium; reading means for reading the data, signal extraction means for receiving the output signal of the reading means and outputting the signal only for a predetermined period, and signal processing means for receiving the output of the signal synchronization means and performing predetermined signal processing. A magnetic recording/reproducing apparatus comprising: a means for controlling the length of a period during which the signal extracting means outputs the signal according to a change in the running speed of the magnetic recording medium.