JPH0442402A - Rectangular wave recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the S/N of a reproducing signal by recording a rectangular wave signal supplied from a rectangular wave signal supply source to a magnetic recording medium with a magnetic head, and amplifying the reproducing signal obtained by scanning the magnetic recording medium with the magnetic head by a reproducing amplifier. CONSTITUTION:This device is equipped with diodes 11, 12 whose terminals with polarity opposite to each other are connected, a recording amplifier 14 connected to one terminals of the diodes 11, 12 via an adjusting resistor 13 which adjusts the current value of an excitation current, the magnetic head 15 whose one terminal is grounded and other terminal is connected to the other terminals of the diodes 11, 12, and which scans a magnetic tape 10, and the reproducing amplifier 17 connected to the connection point of the magnetic head 15 and the diodes 11, 12 via a resistor 16. In a recording mode, a time code signal supplied via a terminal 1 is recorded on the magnetic tape 10 as the rectangular wave signal, and at the time of reproduction mode, a recorded rectangular wave signal is supplied to the reproducing amplifier without being clipped, then, an amplified reproducing signal can be outputted. In such a way, the S/N of the reproducing signal can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention records a rectangular wave signal on a magnetic recording medium, and
The present invention relates to a rectangular wave recording and reproducing device that reproduces recorded rectangular wave signals.

B1 Summary of the Invention The rectangular wave recording/reproducing device according to the present invention includes first and second diodes whose terminals having opposite polarities are connected to each other;
, a square wave signal supply source connected to one end of the second diode, one end of which is grounded, and the other end of which is connected to the first and second diodes.
a magnetic head connected to the other end of the diode to scan the magnetic recording medium; and a regenerative amplifier connected to the connection point between the magnetic head and the first and second diodes, By recording the supplied rectangular wave signal onto a magnetic recording medium using a magnetic head, and by amplifying the reproduction signal obtained by scanning the magnetic recording medium with the magnetic head using a reproduction amplifier, it is possible to differentiate between recording and reproduction operations. In addition, by completely grounding one end of the magnetic head, the S/N of the reproduced signal can be improved, and the number of parts can be reduced compared to the conventional method. It was made so that it could be done.

C8 Conventional technology Magnetic recording media, such as the magnetic tape of a video tape recorder, contain so-called control pulses and other signals used for servo control of the tape speed and switching control of the magnetic head, in addition to the main signals of video and audio signals. , For example, information (data) such as a so-called time code used during editing, etc. to manage recorded video signals, etc. is recorded as the direction of a rectangular wave magnetic field (hereinafter referred to as a rectangular wave signal), Alternatively, recorded information such as time code is played back.

For example, a conventional rectangular wave recording and reproducing device that records time code on a magnetic tape or reproduces a time code recorded on a magnetic tape uses a magnetic helad 51 that scans a magnetic tape 50, as shown in FIG. , a recording amplifier 52 that amplifies the input time code signal supplied via the terminal 41 and supplies excitation current to the magnetic herad 51, and a reproduction amplifier 54 that amplifies the reproduced signal from the magnetic herad 51.
, switches 55 and 56, and a changeover switch 57 controlled by a mode control signal supplied via the terminal 42 to switch between recording operation and reproduction operation.

Then, the recording amplifier 52 amplifies the input time code signal supplied via the terminal 41, and generates an excitation current of 1i.
The magnetic head 5 is connected to the magnetic head 5 through an adjustment resistor 53 that adjusts the current value.
The excitation current is supplied to 1.

Further, the magnetic head 51 is configured such that an excitation current corresponding to a time code from the recording amplifier 52 is inputted from one end thereof, and a reproduced signal is outputted from the other end.

Further, the switch 55 grounds the reproduction signal output end of the magnetic head 51 during a recording operation (hereinafter referred to as a recording mode), and the switch 56 grounds the reproduction signal output end of the magnetic head 51 during a reproduction operation (hereinafter referred to as a reproduction mode). The excitation current input terminal is grounded, and the changeover switch 57 is adapted to ground the input terminal of the recording amplifier 52 in the reproduction mode.

That is, in the rectangular wave recording/reproducing apparatus having the above configuration, in the recording mode, the mode control ff supplied via the terminal 42
Based on the high level (hereinafter referred to as H level) of the fl signal, the changeover switch 57 is controlled to connect the input terminal of the recording amplifier 52 to the terminal 41 side, and the magnetic head 5
The switch 56 is controlled so that the excitation current input terminal of i11.1 is not grounded. , controls the switch 55 to ground the reproduction signal output end of the magnetic head 51. Then, the time code signal supplied via the terminal 41 is amplified by the recording amplifier 52 to produce a rectangular wave signal, that is, the excitation M1 of the magnetic head 51.
'Iit current, and this excitation Mi
ii current is supplied to the magnetic helad 51. As a result, due to a change in the direction of the magnetic field from the magnetic head 51, the magnetic tape 50
A time code is recorded as the direction of a rectangular wave-like magnetic field.

On the other hand, in the reproduction mode, the rectangular wave recording/reproducing apparatus having the above-mentioned configuration, based on the low level (hereinafter referred to as L level) of the mode control signal supplied via the terminal
The switch 56 is controlled so as to ground the excitation ift current input terminal of the magnetic head 51, and the switch 55 is controlled so as to unground the reproduced signal output terminal of the magnetic head 51.
Furthermore, the selector switch 57 is controlled so that the input terminal of the recording amplifier 52 is grounded so that no noise is added to the low-level reproduction signal output from the magnetic head 51.

Then, the reproduction signal from the magnetic herad 51 is transmitted to the reproduction amplifier 5.
4 and output from terminal 43.

D1 Problems to be Solved by the Invention As described above, in the conventional rectangular wave recording/reproducing device, the switches 55, 5 for switching between the recording mode and the reproduction mode are
6. A changeover switch 57 was required, and the circuit configuration was complicated. In addition, in the reproduction mode, since the excitation current end of the magnetic head 51 is grounded using the switch 56 as described above, it cannot be completely grounded due to the contact resistance, and the S/N of the reproduction signal deteriorates. There have also been problems such as so-called fog, in which noise is added to the reproduced signal.

The present invention has been made in view of the above circumstances, and eliminates the need for a mode switching switch for switching between recording mode and playback mode, and also eliminates the need for a mode switch to switch between recording mode and playback mode, and completely grounding one end of the magnetic head to reduce the S of the playback signal. An object of the present invention is to provide a rectangular wave recording/reproducing device which can improve the /N and has a smaller number of parts than the conventional one.

E1 Means for Solving Problems In the rectangular wave recording/reproducing apparatus according to the present invention, in order to solve the above problems, the first
, a second diode, a square wave signal supply source connected to one ends of the first and second diodes, one end of which is grounded, and the other end of which is connected to the other ends of the first and second diodes. a rectangular wave signal supplied from the rectangular wave signal supply source, comprising: a magnetic head connected to scan the magnetic recording medium; and a regenerative amplifier connected to a connection point between the magnetic head and the first and second diodes; The present invention is characterized in that a wave signal is recorded on the magnetic recording medium by the magnetic head, and a reproduction signal obtained by scanning the magnetic recording medium with the magnetic head is amplified by the reproduction amplifier.

F0 action In the rectangular wave recording/reproducing apparatus according to the present invention, in the recording mode, by applying a voltage sufficiently larger than the forward voltage of the first and second diodes from the rectangular wave signal supply source to the magnetic head. , the first and second diodes become conductive, and a rectangular wave signal can be recorded on the magnetic recording medium by the magnetic head, and in the reproduction mode, the level of the reproduction signal from the magnetic head is the same as that of the first and second diodes. is smaller than the forward voltage of the diode, the first and second diodes are cut off, the reproduced signal is supplied to the regenerative amplifier without being clipped, and the amplified reproduced signal is output.

G. Embodiments Hereinafter, embodiments of the rectangular wave recording/reproducing apparatus according to the present invention will be described with reference to the drawings.

In addition to main signals such as video signals and audio signals, magnetic recording media, such as magnetic tape, contain so-called control pulses used for servo control of tape speed and switching control of magnetic heads, and for editing, etc. Information (data) such as a so-called time code for managing recorded video signals etc. is recorded as the direction of a rectangular wave magnetic field (hereinafter referred to as a rectangular wave signal), or a recorded time code etc. information is now played.

As described above, the first embodiment of the rectangular wave recording/reproducing apparatus which records information such as time code as a rectangular wave signal on a magnetic tape or reproduces recorded information such as time code is shown in FIG. As shown, the diode 11 is connected to the diode 11 through an adjustment resistor 13 that adjusts the current value of the excitation current.
a recording amplifier 14 connected to one end of the diode 1112; and an n-air head 15 whose one end is grounded and whose other end is connected to the other end of the diode 1112 and which scans the magnetic tape 10.
and a playback amplifier 17 connected via a resistor 16 to the connection point between the magnetic head 15 and the diode 11, ]2. , the time code signal supplied through the terminal 1 is recorded on the magnetic tape 10 as a rectangular wave magnetic field direction (hereinafter referred to as a rectangular wave signal),
When reproducing the time code recorded as this rectangular wave signal (referred to as reproduction mode), the rectangular wave signal recorded on the magnetic tape 10 is taken out from the terminal 2 as a signal obtained by differentiating the rectangular wave signal. There is.

Next, I will explain the specific operation of this rectangular wave recording/reproducing device.

First, the operation when recording, for example, a time code on the magnetic tape 10 will be explained.

The recording amplifier 14 amplifies the time code signal supplied via the terminal 1 to generate a rectangular wave signal, that is, the magnetic herad 1.
This exciting current is supplied to the magnetic head 15 via an adjustment resistor 13 and diodes 11 and 12 that adjust the current.

By the way, when recording a rectangular wave signal on the magnetic tape 10, a large excitation current is required, and the diode 11.1
For example, a voltage sufficiently large compared to the forward voltage of approximately 0.7 cm, which is the forward voltage of a silicon diode, is applied from the recording amplifier 14 to the magnetic head 15. therefore,
Diodes 11 and 12 become conductive, and recording amplifier 1
The excitation M1 current from M4 flows through the excitation coil of the magnetic head 15.

As a result, the time code is recorded on the magnetic tape 10 as a rectangular wave signal.

Next, the operation when reproducing, for example, a time code recorded as a rectangular wave signal on the magnetic tape 10 will be explained.

The magnetic head 15 detects changes in magnetic flux density from the magnetic tape 10 to generate a reproduction signal, and supplies this reproduction signal to a reproduction amplifier 17 via a resistor 6.

The reproduction amplifier 17 amplifies the reproduction signal and outputs the amplified reproduction signal via the terminal 2.

By the way, the reproduced signal output from the magnetic head 15 is obtained as a waveform obtained by differentiating a rectangular wave signal, and its level (peak value) is sufficiently smaller than the forward voltage of the diodes 11 and 12 (the diode 1112 is in a cut-off state). Therefore, the recording side circuit is separated by the diodes 11 and 12, and the reproduction signal from the magnetic head 15 is supplied to the reproduction amplifier 17 without being clipped, where it is amplified and output from the terminal 2. Ru.

Note that an integrating circuit, a low-pass filter, an equalizer, a comparator, etc. (not shown) are connected to the subsequent stage of the terminal 2, and these circuits convert the reproduced signal containing the differential wave of the rectangular wave signal into a binary signal. The converted playback data, that is, the time code, is played back.

As described above, in the rectangular wave recording and reproducing apparatus according to the present invention,
For example, a time code signal supplied through the terminal 1 is amplified by the recording amplifier I4 and converted into a rectangular wave signal, and this rectangular wave signal is magnetically transmitted through diodes 11 and 12 whose terminals of opposite polarity are connected to each other. In the recording mode, the voltage level of this square wave signal is sufficiently larger than the forward voltage of the diode 11, 12, and
The diodes 11 and 12 become conductive, and the magnetic head 1
An excitation current can be passed through the excitation coil 5, and data such as a time code can be recorded on the magnetic tape 10. In the reproduction mode, the level of the reproduction signal from the magnetic head 15 is sufficiently lower than the forward voltage of the diodes 11 and 12, and the diodes 11 and 12 are cut off, so that the recording side circuit is disconnected. As a result, the reproduction signal from the magnetic field 15 can be amplified and output by the reproduction amplifier 17 without clipping. That is, this rectangular wave recording/reproducing apparatus does not require a mode switching switch for switching between the recording mode and the reproducing mode unlike the conventional rectangular wave recording/reproducing apparatus. Since it is directly grounded, instead of being grounded through a switch as in a wave recording/reproducing device, the S/N of the reproduced signal does not deteriorate.

Next, a second embodiment of the rectangular wave recording/reproducing apparatus according to the present invention will be described.

In this rectangular wave recording/reproducing device, as shown in Fig. 2, a positive voltage ■ from a positive voltage source and a negative voltage ■ from a negative voltage source
- a changeover switch 21 that selects and outputs the output of the changeover switch 21 and a ground point; a changeover switch 23 that selects and outputs the output of the changeover switch 21 and the ground point; A mode control circuit 22 that controls the changeover switch 21 based on the mode control signal and controls the changeover switch 23 based on the mode control signal supplied via the terminal 6, and terminals of opposite polarity are connected to each other, Diodes 25 and 26, one end of which is connected to the output of the changeover switch 23 via the adjustment resistor 24 and the other end connected to the magnetic head 27, record data such as a time code on the magnetic tape 20, or record data such as a time code on the magnetic tape 20. The magnetic head 27 scans the magnetic tape 20 to reproduce data such as time codes and the like, and a reproduction amplifier 29 amplifies the reproduction signal from the magnetic head 27.

The changeover switch 21 has two switches connected in series.
One end of the analog switch 21a is connected to a positive voltage source (■,), and one end of the analog switch 21b is connected to a negative voltage source (■,).
(2) -), and the positive voltage V and negative voltage (2) are output as ashes. This changeover switch 2
The output of 1 is supplied to the changeover switch 23.

Further, the changeover switch 23 is composed of two analog switches 23a and 23b connected in series, one end of the analog switch 23a is connected to the output of the changeover switch 21, and one end of the analog switch 23b is a ground point. The output of the changeover switch 21 and the ground point are selected and output. The output of the changeover switch 23 is supplied to the magnetic head 27 via the adjustment resistor 24, which adjusts the current value of the excitation current supplied to the magnetic head 27, and the diodes 25, 26.

The mode control circuit 22 also receives, for example, an input time code signal, which is supplied via the terminals 5 and 6, respectively.
Consisting of negative logic circuits 22a and 22b each outputting a negative logic (hereinafter referred to as an inverted signal) of a mode control signal,
The analog switch 21a is controlled by an input time code signal, the analog switch 21b is controlled by an inverted time code signal, the analog switch 23a is controlled by a mode control signal, and the analog switch 23b is controlled by an inverted mode control signal. It looks like this.

The magnetic head 27 has one end grounded, the other end connected to the diodes 25 and 26, and a resistor 2.
8 to the reproduction amplifier 29, the magnetic tape 20 is scanned, and, for example, a time code is recorded on the magnetic tape 20, and the recorded time code is reproduced.

That is, in this rectangular wave recording/reproducing device, the magnetic tape 2
When recording data, such as a time code, on the magnetic tape 2, the time code signal supplied via the terminal 5 is recorded on the magnetic tape 2.
0 as the direction of a rectangular wave-like magnetic field (hereinafter referred to as a rectangular wave signal), and when reproducing the time code recorded as this rectangular wave signal, the rectangular wave signal recorded on the magnetic tape 20 becomes the rectangular wave signal. terminal 7 as a signal obtained by differentiating
It is designed to be taken out from

Next, the specific operation of this rectangular wave recording/reproducing apparatus will be explained.

First, the operation when recording, for example, a time code on the magnetic tape 10 will be explained.

For example, when the time code signal supplied via the terminal 5 is at H level, the mode control 'n circuit 22 turns on the analog switch 21a and turns the analog switch 21b into an ON state.
is controlled to be in the OFF state, and when the time code signal is at L level, the analog switch 21a is controlled to be in the OFF state, and the analog switch 21b is controlled to be in the ON state. That is, the changeover switch 2 consists of analog switches 21a and 21b.
1 is controlled by a time code signal, for example, when the time code signal is at H level, it outputs a voltage from a positive voltage source, and when the time code signal is at L level,
Outputs voltage ■- from a negative voltage source. Also, at the same time,
This mode control circuit 22 controls the analog switch 23a to be in the ON state and the analog switch 23b to be in the OFF state when the mode control signal supplied via the terminal 6 is, for example, at the H level, and the mode control signal is at the L level. At this time, the analog switch 23a is controlled to be in the OFF state, and the analog switch 23b is controlled to be in the ON state. In the recording mode, the output of the selector switch 21 is selected and output.

Then, these positive voltages or negative voltages V- are transferred to the magnetic field 7 via the adjustment resistor 24 and the diodes 25 and 26.
The voltage is applied to the excitation coil of the power source 27.

By the way, as mentioned above, when recording a rectangular wave signal on the magnetic tape 20, a large excitation current is required, and the forward direction i+tπ of the diodes 25 and 26, for example, approximately 0.7■ which is the forward direction voltage of a silicon diode. A sufficiently large voltage is applied from the changeover switch 21 to the magnetic head 27 in comparison. Therefore, the diodes 25 and 26 become conductive, and the excitation VAti from the changeover switch 21 flows to the excitation coil of the magnetic head 27. As a result, the time code is recorded on the magnetic tape 20 as a rectangular wave signal.

Next, the operation when reproducing, for example, a time code recorded as a rectangular wave signal on the magnetic tape 20 will be explained.

The mode control circuit 22 controls the analog switch 23a of the changeover switch 23 to be in the OFF state and the analog switch 23b to be in the ON state based on the L level of the mode and control signal supplied via the terminal 6. That is, the recording side circuit connected to the magnetic head 27 is connected to the magnetic head 2.
7, it is grounded via diodes 25, 26 and adjustment resistor 24.

Thus, the magnetic head 27 detects changes in magnetic flux density from the magnetic tape 20 and generates a reproduction signal, and this reproduction signal is supplied to the reproduction amplifier 29 via the resistor 28.

The reproduction amplifier 29 amplifies the reproduction signal and outputs the amplified reproduction signal via the terminal 7.

By the way, the reproduced signal output from the magnetic helad 27 is obtained as a waveform obtained by differentiating a rectangular wave signal, and its level (peak value) is sufficiently smaller than the forward voltage of the diode 25.26, and the diode 25.26 is It will be in a cut-off state.

Therefore, the recording side circuit is separated by the diodes 25 and 26, and the reproduction signal from the magnetic head 27 is not clipped (the reproduction amplifier 29
The signal is amplified and output from terminal 7.

Furthermore, as described above, by grounding the recording side circuit via the adjustment resistor 24, it is possible to prevent external noise from entering the reproduced signal.

Note that, as in the first embodiment described above, an integrating circuit, a low-pass filter, an equalizer, a comparator, etc. (not shown) are connected to the subsequent stage of the terminal 7, and these circuits generate a rectangular wave. Binary reproduction data, that is, time code, is reproduced from a reproduction signal having a differential wave of the signal.

As described above, in this rectangular wave recording and reproducing device, the changeover switch 7 is controlled based on the time code signal supplied through the terminal 5, and the positive voltage or negative voltage from the changeover switch 21 is controlled. The voltage V- is applied to the magnetic head 2 through diodes 25 and 26 whose terminals of opposite polarity are connected to each other.
7, in the recording mode, the positive voltage V0 and negative voltage V- are sufficiently larger than the forward voltage of the diode 25.26, the diode 25.26 becomes conductive, and the magnetic head 27 is excited. Encourage the coil! fiii
i-stream can be streamed, and data such as time codes can be recorded on the magnetic chip 120. In the reproduction mode, the level of the reproduction signal from the magnetic head 27 is sufficiently lower than the forward voltage of the diode 25.26, and the diode 25.26 is cut off, and the adjustment resistor 24
The diodes 25 and 26 are grounded through the diodes 25 and 26. As a result, the reproduction signal from the magnetic herad 27 can be amplified and outputted by the reproduction amplifier 29 without being clipped by the diodes 25 and 26, and
By grounding the diodes 25 and 26, it is possible to prevent external noise from entering the reproduced signal. That is, this rectangular wave recording and reproducing apparatus requires a plurality of mode switching switches for switching between recording mode and reproducing mode, as in the conventional rectangular wave recording and reproducing apparatus. Since it is not grounded through a switch as in conventional rectangular wave recording/reproducing devices, but is directly grounded, the S/N of the reproduced signal does not deteriorate.

! L Effects of the Invention As is clear from the above explanation, in the rectangular wave recording/reproducing apparatus according to the present invention, the rectangular wave signal from the rectangular wave signal supply source generated based on recorded information is transmitted to terminals of opposite polarity. The magnetic recording medium, one end of which is grounded, is supplied to the magnetic head that scans the magnetic recording medium through the first and second diodes, which are connected to each other. By amplifying the reproduction signal from the magnetic head by the reproduction amplifier, the first and second diodes become conductive during recording operation, and an excitation current corresponding to the rectangular wave signal from the rectangular wave signal supply source is generated. can be passed through the excitation coil of the magnetic head, and information such as time codes can be recorded on the magnetic recording medium. In addition, during the reproduction operation, the first and second diodes are cut off, and the recording side circuit can be disconnected, and the reproduction signal from the magnetic head can be amplified by the reproduction amplifier without clipping. Information such as a time code recorded on a recording medium can be reproduced. That is,
Unlike conventional models, there is no need for a mode switch to switch between recording mode and playback mode, and by completely grounding one end of the magnetic head, the S/N of the reproduced signal is improved compared to conventional methods. be able to. In other words,
The number of parts and harnesses can be reduced compared to the past, the mounting area can be reduced, costs can be reduced, and reliability can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a first embodiment of a rectangular wave recording/reproducing apparatus according to the present invention, and FIG. 2 is a block circuit diagram of a second embodiment of a rectangular wave recording/reproducing apparatus according to the present invention. 3 is a block circuit diagram of a conventional rectangular wave recording/reproducing device. 10.20 ... Magnetic tape 1112.25.26 ... Diode 14 ...
... Recording amplifier 21 ... Selector switch 15.27 ... Magnetic head 17.29 ... Playback amplifier

Claims (1)

[Claims] First and second diodes whose terminals have opposite polarities are connected to each other, a rectangular wave signal supply source connected to one ends of the first and second diodes, and one end of which is grounded. and the other end is connected to the other ends of the first and second diodes, and is connected to a magnetic head that scans the magnetic recording medium, and a connection point between the magnetic head and the first and second diodes. a reproducing amplifier, the rectangular wave signal supplied from the rectangular wave signal supply source is recorded on the magnetic recording medium by the magnetic head, and the magnetic recording medium is scanned by the magnetic head. A rectangular wave recording and reproducing device characterized in that a signal is amplified by the reproducing amplifier described above.