JP3203155B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and in particular, in order to realize, for example, a tape refresh function, a video and audio signal by giving an erasure signal only to a rotary head for recording a Hi-Fi audio signal. The present invention relates to a magnetic recording / reproducing apparatus that operates as an erasing head for erasing.

[0002]

2. Description of the Related Art Hitherto, in a magnetic recording / reproducing apparatus such as a video tape recorder, Hi-F is used as a method for erasing video and audio signals in a section from a full width erasing head to a rotating head when a tape refresh function is realized.
A method of operating an audio rotating head for recording an i audio signal as an erasing head has been adopted in terms of design easiness, cost, and productivity. Since this audio rotary head usually has a head width close to the track width of LP (29 μm), it is erased at a speed equal to or less than the width of the audio rotary head, for example, at a speed of EP (19.2 μm) so as not to be erased. Is performed. The erasing frequency at this time is the carrier frequency of 1.3 MHz and 1.7 MHz as in the case of normal recording.

If the control pulse in the portion erased by the audio rotary head is left unerased, a system error may be caused by the partially left control pulse. Was not erased.

[0004]

Since the control pulse is not erased as described above, if the original recording mode of the tape refreshed by the conventional method is, for example, the SP mode, the erase track at the time of the tape refresh is Since the signal of the Hi-Fi audio track is formed in accordance with the EP mode, the signal of the Hi-Fi audio track becomes a triple output speed of the EP, that is, the head output of the SP mode, and a humming sound is generated due to the cut-off of the envelope of the Hi-Fi audio. Was.

[0005] In addition, Hi-F is applied to an unrecorded tape while a magnetic field for tape orientation processing is applied.
When the i sound is recorded, there is a disadvantage that the tape is magnetized to a saturated state and the Hi-Fi beat is emphasized during reproduction. Therefore, the main object of the present invention is Hi
-Buzzy sound or Hi-F due to broken Fi audio envelope
An object of the present invention is to provide a magnetic recording / reproducing apparatus capable of reducing noise due to i-beat.

[0006] The present invention relates to a Hi- recording device for recording an audio signal.
Including the Fi head, the recording signal is only for the Hi-Fi head.
From the full-width erase head
Video and audio signals recorded in the section up to the rotating head
Erasing data at the same tape transfer speed as in EP mode
In recording and reproducing apparatus, the frequency between the frequency of the erasing signal video signal band and an audio signal band and the basic transport frequency
A magnetic recording / reproducing apparatus characterized in that the same frequency is set as the number of spurious frequencies .

[0007]

When a tape refresh mode for erasing video and audio signals is set by a key input signal, for example, the Hi-Fi audio I / O is output from the system microcomputer.
A high-level erase command signal is output to C and the frequency / current switching circuit. The Hi-Fi head has a frequency between the video signal band and the audio signal band.
In addition, an erasing signal having the same frequency as the spurious frequency of the basic carrier is applied, and the video and audio signals recorded on the tape are erased. At this time, since the concrete is set to a frequency higher than the audio signal band (2.0 MHz or less), the audio signal reproduced by the Hi-Fi heads, Hi
-It is determined by the Fi audio IC that the signal is not a Hi-Fi audio signal. Therefore, the Hi-Fi head is
A signal of a track different from the erased track, that is, a track on which an audio signal is recorded in a magnetic recording / reproducing apparatus of a fixed head recording system other than the Hi-Fi audio system is read. Further, the tape to which a magnetic field is applied for the tape orientation processing is brought into a zero magnetic field state by the tape refresh, so that the Hi-Fi audio signal recorded thereon is reproduced as a signal having a suppressed Hi-Fi beat level. Is done. Then, the erasing frequency is set to the video signal band (3.
(4 MHz to 4.4 MHz), there is almost no effect on image quality performance. In addition, video signal band
Frequency between the band and the audio signal band, and the basic carrier
Wave spurious frequency (0.4MHz, 0.9MHz,
2.1MHz and 2.6MHz)
(2.1 MHz and 2.6 MHz)
Side band generation is suppressed to prevent Hi-Fi beats.
Can be stopped.

[0008]

According to the present invention, an audio signal is recorded.
Frequency and is and basic between the frequency of the erasing signal applied to the Hi-Fi heads and the video signal band and the audio signal band
Since the frequency is set to be the same as the spurious frequency of the carrier frequency, noise due to a pop noise or Hi-Fi beat does not occur during reproduction. The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0009]

1 shows a magnetic recording / reproducing apparatus 1 according to this embodiment shown in FIG.
0 includes a cylinder 11 that rotates in the direction of arrow A during recording or normal reproduction, and a first rotary head 26 and a second rotary head 20 are disposed on the cylinder 11. The second rotating head 20 includes a first head 20a and a first head 20a.
A second head 20b is attached to the tape 13 at 0 ° back-to-back, and an FM-modulated audio signal is recorded on the tape 13 by the first head 20a and the second head 20b. Then, the video signal is superimposed on this audio signal,
Recording is performed by the first rotating head 26 including the first head 26a and the second head 26b. That is, the magnetic recording / reproducing device 10 employs the Hi-Fi audio system.

Referring to FIG. 2, magnetic recording / reproducing apparatus 10
Includes a system microcomputer 12 to which mode command information such as recording, reproduction, and erasing (tape refresh) is input by key. Syscon microcomputer 1
When the mode command information is input to the system controller 2, a mode command signal is output from the system microcomputer 12 to the Hi-Fi audio IC 14, and when the mode command information is recording or reproduction, the video IC 22 A recording command signal or a reproduction command signal is output.

The Hi-Fi audio IC 14 is
It is connected to a frequency / current switching circuit 16 in which the oscillation frequency and the current level are switched. The frequency / current switching circuit 16 corresponds to FIG.
As shown in (1), the switch includes a changeover switch 28, a changeover switch 30, and a changeover switch 32, and the changeover switch 28 outputs from the Hi-Fi audio IC 14.
On / off control of a 3 MHz signal is performed. The changeover switch 30 switches the signal current simultaneously with the changeover of the frequency by the changeover switch 32. That is,
When the changeover switch 28 is switched to the L side, that is, the terminal 28b side, the Hi-Fi audio IC 14
The signal of 1.3 MHz from the terminal 14a is supplied to the audio preamplifier IC 18 through the changeover switch 28. However, when the changeover switch 28 is switched to the H side, that is, the terminal 28a side, the 1.3 MHz signal from the terminal 14a is not supplied to the audio preamplifier IC 18.

When the changeover switch 32 is connected to the L side, that is, the terminal 32b, the Hi-Fi audio IC 1
Since the resistor connection 34 is connected to the terminal 14c of the fourth
1.7 MH from terminal 14b of Fi audio IC 14
The signal of z is output. When the changeover switch 32 is switched to the H side, that is, the terminal 32a, the resistor connection 36 is connected to the terminal 14c, and a 2.1 MHz signal is output from the terminal 14b of the Hi-Fi audio IC 14. That is, the frequency of the signal output from the Hi-Fi audio IC 14 is 1.7 M by the switch 32.
Hz or 2.1 MHz.

Further, when the changeover switch 30 is connected to the L side, that is, the terminal 30b, the 1.7 MHz signal from the terminal 14b is supplied to the audio preamplifier IC 18 via the resistor 31a and the changeover switch 30. When the changeover switch 30 is switched to the H side, that is, to the terminal 30a, 2.1 MHz output from the terminal 14b is output.
Is supplied to the audio preamplifier IC 18 via the changeover switch 30 and the resistor 31b. Here, since the resistances 31a and 31b are set so as to satisfy the relation of resistance 31a> resistance 31b, the signal current of 2.1 MHz output from the terminal 14b is larger than the signal current of 1.7 MHz. Become. In other words, the changeover switch 30 makes the erasing current at the time of tape refresh larger than the recording current at the time of normal recording.

In operation, when the recording mode is set by a key input signal, the system microcomputer 12 outputs
A recording command signal is given to Hi-Fi audio IC 14 and video IC 22. Accordingly, Hi-Fi
From the audio IC 14, the carrier frequency is 1.3 MHz.
z and 1.7 MHz of the recorded audio signal are output, and the second rotary head 2 is output via the audio preamplifier IC 18.
0 is given. Similarly, a recording video signal is output from the video IC 22, and is output via the video preamplifier IC 24.
The video is provided to the first rotary head 26 and is recorded on the tape 13.

When the reproduction mode is set by the key input signal, the audio signal reproduced by the second rotary head 20 is output to the H level via the audio preamplifier IC 18.
The input to the i-Fi audio IC 14 and this Hi-F
In the i audio IC 14, this audio signal is Hi-
It is determined whether the signal is a Fi audio signal. The video signal reproduced by the first rotary head 26 is input to the video IC 22 via the video preamplifier IC 24.

When the erase (tape refresh) mode is set by a key input signal, the system microcomputer 12
Outputs a high-level erase command signal to the Hi-Fi audio IC 14 and the frequency / current switching circuit 16. Accordingly, the changeover switch 28, the changeover switch 30, and the changeover switch 32 are all switched to the H side, that is, the terminals 28a, 30a, and 32a. Therefore, the 1.3 MHz signal from the terminal 14a is turned off, and the 2.1 MHz erase signal from the terminal 14b is supplied to the audio preamplifier IC 18 through the changeover switch 30 and the resistor 31b. Therefore, the second rotary head 20 is supplied with an erase signal having a frequency different from that of the recording audio signal and a current larger than that, and the tape 13 (see FIG. 1) is erased by the erase signal.

FIGS. 4 to 6 show energy distribution diagrams in the frequency spectrum of the second rotary head 20. FIG. FIG. 4 shows that the erasing frequencies of the unused tape 13 on which the tape orientation processing has been performed are, for example, 1.3 MHz and 1.7 MHz. FIG. 4 is an energy distribution diagram of the audio signal, in which four beats indicated by arrows are generated (emphasized) as can be clearly understood from the diagram. Specifically, the lower 0.4% caused by spurious from the 1.3 MHz and 1.7 MHz basic carriers.
MHz, 0.9MHz, 2.1MHz and 2.6MH
This is the beat of z.

On the other hand, the energy distribution diagram shown in FIG. 5 shows that the tape 13 on which the orientation process has been performed is erased by using the magnetic recording / reproducing apparatus 10 of the above embodiment.
5 is a spectrum of the second rotary head 20 when recording and reproducing. As is apparent from comparison with FIG.
It can be seen that the beat level at 4 MHz has decreased.

FIG. 6 shows an erase frequency of 2.2 on the tape 13 which has been subjected to the orientation process for comparison.
5 shows a spectrum of the second rotary head 20 on which recording and reproduction are performed after an erasing process is performed at 5 MHz. As can be seen from FIG. 6, 1.3 MHz and 1.7 MHz
, Side bands (1.45 MHz, 1.85 MHz) not shown in FIGS. 4 and 5 are generated.
Although illustration is omitted, the erasing frequency is set to, for example, 2.0
Even when the frequency is set to MHz, side bands similar to those shown in FIG. 6 are generated around 1.3 MHz and 1.7 MHz.

As described above, the erasing frequency is set to a frequency different from and close to 0.4 MHz, 0.9 MHz, 2.1 MHz, and 2.6 MHz generated by spurious signals from the 1.3 MHz and 1.7 MHz basic carriers. If set, as shown in FIG. 6, a side band is generated and causes noise (Hi-Fi beat), so that the erasing frequency is preferably set to be the same as any of the above four frequencies.

On the other hand, the hi-fi audio IC 14 uses the Hi-Fi audio IC 14 to prevent the occurrence of the pop noise generated when erasing the tape recorded in the SP mode.
It is necessary not to make i determination. That is,
If the audio signal component has a basic carrier frequency of 1.3 MHz or 1.7 MHz, the Hi-Fi audio IC 1
4 determines that the audio signal is a Hi-Fi audio signal, and in this embodiment,
The erasing frequency is set to a value exceeding 2.0 MHz. In addition, it is necessary that the erasing frequency does not adversely affect the video signal. Therefore, in this embodiment, the erasing frequency is not 2.6 MHz but a distance from the video signal band (3.4 MHz to 4.4 MHz). 2.1 MH
z.

As described above, if the erase frequency at the time of tape refresh is set to 2.1 MHz, the Hi-Fi audio IC 14 determines that the audio signal reproduced from the second rotary head 20 is not a Hi-Fi audio signal. As a result, no popping noise is generated due to the envelope being broken. Therefore, in a system in which the control pulse is not erased at the time of tape refresh, even if the tape recorded in the SP mode is erased (tape refresh) and then recorded in the EP mode, unpleasant noise (humming noise) may occur. Absent. Even if an audio signal is recorded on the magnetic tape subjected to the orientation process by the second rotary head 20, the erasing frequency is set to 2.1 MHz as described above.
By setting to z, the tape 13 is brought to a zero magnetic field state and H
The generation of the i-Fi beat is suppressed (see FIG. 5).

The above-described embodiment is an NTSC model, and has a carrier frequency of 1.4 MHz and 1.6 MHz.
In the PAL model, the erasing frequency is set to, for example, 2.2 MHz.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing a first rotary head and a second rotary head used in the embodiment in FIG. 2;

FIG. 2 is a block diagram showing one embodiment of the present invention.

FIG. 3 is a circuit diagram showing a Hi-Fi audio IC and a frequency / current switching circuit of the embodiment in FIG. 2;

FIG. 4 shows the orientation-treated tape,
FIG. 11 is an energy distribution diagram of an audio signal recorded and reproduced after an erasing process is performed by a conventional magnetic recording and reproducing apparatus.

FIG. 5 shows a tape subjected to an orientation process.
FIG. 4 is an energy distribution diagram of an audio signal recorded and reproduced after an erasing process is performed by the magnetic recording and reproducing apparatus of the embodiment in FIG. 2.

FIG. 6 shows a tape subjected to an orientation process.
FIG. 11 is an energy distribution diagram of an audio signal recorded and reproduced after performing an erasing process at an erasing frequency of 2.25 MHz for comparison.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Magnetic recording / reproducing apparatus 12 ... System microcomputer 14 ... Hi-Fi audio IC 16 ... Frequency / current switching circuit 18 ... Audio preamplifier IC 20 ... 2nd rotary head 26 ... 1st rotary head

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 5/024 601 H04N 5/91

Claims (1)

(57) [Claims] An audio signal recording apparatus includes a Hi-Fi head.
Larger than the recording signal only in the Hi-Fi head.
Apply a current erase signal to change the full width erase head to the rotating head.
Video and audio signals recorded in the section up to
Magnetic recording / reproducing device that erases at the same tape transfer speed as the tape
In spurious circumference of frequencies a and and fundamental carrier frequency between the video signal band and the audio signal band frequency of the erasing signal
A magnetic recording / reproducing apparatus, wherein the same frequency as the wave number is set.