JPH0731765B2 - Reciprocating playback type magnetic recording / playback device - Google Patents

Description

The present invention relates to a reciprocal reproducing magnetic recording / reproducing apparatus including a reproducing head using a magnetoresistive element.

[Prior Art] In recent years, an analog signal such as voice is converted into a digital signal and further modulated by a predetermined modulation method to generate a digital signal which can be synchronized with a self-clock, and this is recorded on a magnetic recording medium such as a magnetic tape. Digital magnetic recording / reproducing devices for recording and reproducing have been developed.

In this digital magnetic recording / reproducing apparatus, when recording a digital signal converted from an analog signal on a magnetic recording medium, it is much more difficult than an analog magnetic recording / reproducing apparatus for recording / reproducing a conventional analog signal on a magnetic recording medium. It requires a wide frequency band. Therefore, one of the magnetic recording media
In order to reduce the recording density per track, the recorded digital signal is time-divided into a plurality of channels and the divided digital signals are recorded in a plurality of corresponding tracks on the magnetic recording medium. In addition, this digital magnetic recording / reproducing apparatus is provided with a reproducing head using a magnetoresistive element capable of scanning a plurality of tracks and capable of being made thin and compact.

FIG. 2 shows a one-way drive equipped with a reproducing head using a magnetoresistive element.
FIG. 3 is a block diagram of a reproducing circuit of a 20-track digital magnetic recording / reproducing apparatus.

In FIG. 2, reference numeral 30 is a reproducing head circuit of the first channel # 1, and in the reproducing head circuit 30, a constant current source CS ₁
MR element MR ₁ whose one end is a thin film magnetic head for reproduction
Of the constant current source CS ₁ and the magnetoresistive element M.
The other ends of R ₁ are both connected to ground. The connection point between the constant current source CS ₁ and the magnetoresistive element MR ₁ is connected to the input terminal of the reproduction amplifier 6 via the coupling capacitor 4 of the reproduction amplifier circuit 3, and the input terminal of the reproduction amplifier 6 is connected via the resistor 5. Connected to earth. Further, the output terminal of the reproduction amplifier 6 is connected to the input terminal of the first channel # 1 of the analog multiplexer 7.

The reproducing head circuit 30 of the second channel # 2 to the twentieth channel # 20 and the reproducing amplifier circuit 3 including the coupling capacitor 4, the resistor 5 and the reproducing amplifier 6 are similarly configured, and the output terminal of the reproducing amplifier 6 of each channel is , Are connected to the input terminals of the corresponding channels of the analog multiplexer 7.

From the 1st channel # 1 to the 20th channel # 20
By scanning the ₂₀ magnetoresistive elements MR _{1 to} MR ₂₀ on the magnetic tape that is the magnetic recording medium, a recording voltage signal is obtained across the magnetoresistive elements MR _{1 to} MR ₂₀ of each channel.
The respective signals are amplified in the reproduction amplifier circuit 3 and then connected to the input terminals of the respective channels of the analog multiplexer 7.

The reproduced signal of each channel input to the analog multiplexer 7 is sequentially selected in a time division manner and input to the A / D converter 8 from the output terminal. Next, the signal input to the A / D converter 8 is converted into a digital signal, and the digital waveform equalization circuit 9 performs waveform equalization for reducing distortion and waveform interference of the digital reproduction signal. The digital PLL circuit 10 extracts the reproduction clock and the reproduction data signal from the waveform-equalized digital reproduction signal, and the digital demodulation circuit 11 identifies and demodulates the reproduction data signal.

The demodulated reproduced data signal is the digital signal processing circuit 12
Signal processing such as error correction is performed at the end, and finally the D / A converter 13
In, it is converted into an analog signal and is output to the output terminal 14 as an analog audio signal. Digital PL
The L circuit 10 and the digital demodulation circuit 11 are disclosed, for example, in JP-A-59-9.
It is described in detail in Japanese Patent No. 2410 and the like, and the explanation is omitted here.

FIGS. 3A and 3B show the positional relationship between the recording track of the magnetic tape 21 and the magnetoresistive element of the reproducing head 22 in the forward reproduction and the backward reproduction when the magnetic recording / reproducing apparatus of FIG. 2 is used. FIG. In FIGS. 3A and 3B, a total of 40 recording tracks of 20 forward tracks and 20 return tracks on the magnetic tape 21 are arranged in the longitudinal direction of the magnetic tape 21 with a space between each recording track. Recording tracks T ₁ , T ₂ , ..., T ₂₀ on the forward path and recording tracks T ₂₀ ′, ..., T ₂ ′, T _{1 on the} backward path extending from the widthwise end of the magnetic tape 21 toward the other end. It is provided in the order of ′. On the other hand, the magnetoresistance element MR ₁ ～MR ₂₀ of the first channel, second 20 channel playback head 22, magnetic tape 21
Recording tracks T _{1 to} T ₂₀ or T ₁ ′ to T ₂₀ ′ are arranged side by side with a space between each element.

For example, in the case of a one-way reproduction type magnetic recording / reproducing apparatus, in the outward reproduction, as shown in FIG. 3 (A), the magnetic recording elements MR _{1 to} MR ₂₀ of the reproducing head 22 are respectively the outward recording tracks T.
_{1 to} T ₂₀ , while in the backward path reproduction, the cartridge containing the magnetic tape is turned upside down and turned over, and as shown in FIG. 3 (B), the magnetic recording element MR ₁ of the reproducing head 22 is read. ~ MR ₂₀ is the recording track T ₁ ′ on the return path
Scan ~ T ₂₀ '.

Further, in the case of a reciprocal reproduction type magnetic recording / reproducing apparatus, a forward recording track T ₂₀ and a backward recording track T ₂₀ ′ on the magnetic tape 21 are used.
The reproducing head 22 is rotated at an angle of 180 ° around the intermediate point between the two, and the cartridge containing the magnetic tape is turned upside down without being turned over.
And a method of performing scanning of the reproducing head 22 on the forward and backward paths as shown in FIG. However, for example, in a digital audio tape recorder, it is required that the number of tracks is n = 20, the track pitch, which is the distance between the tracks, is 80 μm, and the track width is 50 μm. Since the frequency band is used, the accuracy of each azimuth becomes severe. Therefore, to achieve these, the playback head
The rotation mechanism of 22 is expensive and large, and it is difficult to realize a portable tape recorder or the like.

As a method for improving it, as shown in FIG. 4, the magnetoresistive element MR _1, MR ₂ for forward magnetoresistive element, ..., magnetoresistive element MR ₂₀ for MR ₂₀ and backward ', ..., MR ₂ In order of ′, MR ₁ ′,
Each of the magnetoresistive elements has recording tracks T ₁ , T ₂ , ..., T _{20 on} the forward path of the magnetic tape 21 and recording tracks T ₂₀ ′, ..., T on the return path.
A fixed reproducing head 23 is formed by arranging T ₂ ′ and T ₁ ′ side by side so that they can be scanned, and the magnetic tape 21 is made to run in the reverse direction on the forward path and the backward path so that each magnetic resistance element of the reproducing head 23 is a magnetic tape.
A method of scanning and reproducing on 21 predetermined tracks has been proposed.

[Problems to be Solved by the Invention] However, the magnetoresistive element MR ₁ for reciprocal reproduction shown in FIG.
~ MR ₂₀ , MR ₂₀ ′ ~ MR ₁ ′ fixed type reproducing head 23
When a reproducing circuit of a reciprocating reproducing type digital magnetic recording / reproducing apparatus is constructed by using the circuit, the circuit from the analog multiplexer 7 to the output terminal 14 in FIG. 2 can be commonly used for the forward path reproduction and the backward path reproduction. The constant current source and the reproducing / amplifying circuit 3 are connected to one magnetic recording element of the head 23. Therefore, in the case of a device of 20 tracks one way and 40 tracks reciprocating, for a total of 40 magnetic recording elements for reproducing forward and reproducing backward. It is necessary to provide a total of 40 constant current sources and a regenerative amplifier circuit 3. Therefore, there has been a problem that the circuit scale increases and the total power consumption increases.

[Object of the Invention] An object of the present invention is to solve the above problems and to provide a reciprocal reproducing magnetic recording / reproducing apparatus which can reduce the circuit scale as compared with the conventional example and consumes less power.

[Constitution of the Invention] According to the present invention, a forward read magnetic path and a backward read magnetic resistance element respectively provided so as to be able to scan a forward track and a backward track on a magnetic recording medium, and a current is commonly supplied to the magnetic resistance element. A constant current source and switching means for selectively switching the forward path reproducing magnetic resistance element and the backward path reproducing magnetic resistance element to connect to the constant current source are provided.

[Embodiment] FIG. 1 is a block diagram of a reproducing circuit of a reciprocal reproducing magnetic recording / reproducing apparatus showing an embodiment of the present invention.

This circuit uses two magnetoresistive elements per channel, which are used as thin film magnetic heads for forward and backward paths in the reproducing head circuit, and to switch between them.
Equipped with switching transistors, two reproducing head circuits 30 and 2 per channel for forward and backward
The circuit scale is made smaller than that of the conventional example of FIG. 2 in which one reproduction amplifier circuit 3 is required.

The circuit of FIG. 1 is different from the circuit of FIG. 2 in the reproduction head circuit 1, and other reproduction amplification circuit 33 analog multiplexer 7, A / D converter 8, digital waveform equalization circuit 9, digital PLL. The configurations and operations of the circuit 10, the digital demodulation circuit 11, the digital signal processing circuit 12 and the D / A converter 13 are the same as those of the conventional example shown in FIG. Also, the fourth
Similar to the figure, the first channel # 1 to 20 for reproduction
Channel # magnetoresistive element MR _1, MR ₂ of 20, ..., MR ₂₀ and a 20 channel # 20 to the first channel # of backward reproducing
, 1 MR ₂₀ ′, ..., MR ₂ ′, MR ₁ ′ are arranged side by side,
Recording each of the magnetoresistive element is a forward path of the magnetic tape 21 tracks _{T 1, T 2, ...,} T 20 and return of the recording track T ₁ '~
It can scan T ₂₀ ′.

In FIG. 1, the reproducing head circuit 1 is the first channel # 1.
Of a circuit for the forward reproduction and backward reproduction, one end of the outward path reproducing magnetoresistive element MR ₁ a switching transistor Q
It is connected to the emitter of a and the other end of the magnetoresistive element MR ₁ is connected to ground. In addition, the magnetoresistive element MR ₁ ′ for return path reproduction
Has one end connected to the emitter of the switching transistor Qb and the other end of the magnetoresistive element MR ₁ ′ connected to ground. The bases of the transistors Qa and Qb are connected to the common terminal of the switch 2a and the common terminal of the switch 2b, respectively, and the R-side terminal of the switch 2a and the F-side terminal of the switch 2b are connected together and connected to the ground. Also, switch 2a
The F side terminal and the R side terminal of the switch 2b are connected together and connected to the positive electrode of the DC voltage source B, and the negative electrode of the DC voltage source B is connected to the ground. The switches 2a and 2b are interlocked with each other and are switched to the F side for forward path reproduction and to the R side for backward path reproduction.

The collector of the transistor Qa and the collector of the transistor Qb are connected together and connected to one end of the constant current source CS ₁ and also to one end of the coupling capacitor 4 of the reproduction amplifier circuit 3 as the output of the reproduction head circuit 1. To be done. The circuits after the coupling capacitor 4 are connected in the same manner as in the conventional example of FIG. 2 as described above. The other end of the constant current source CS ₁ is connected to the ground.

Furthermore, the second channel # 2 to the twentieth channel # 20
The reproducing head circuit 1 and the reproducing amplifier circuit 3 are connected in the same manner as that of the above-mentioned first channel # 1.

With the configuration as described above, first, when the forward path reproduction is performed, the switches 2a and 2b are switched to the F side. Thereby, the positive voltage of the DC voltage source B is applied to the base of the transistor Qa via the switch a, while the base of the transistor Qb is grounded via the switch 2b to ground.
Is turned on and the transistor Qb is turned off, and a constant current flows from the constant current source CS ₁ to the magnetoresistive element MR ₁ via the transistor Qa.

Similar to the conventional example shown in FIG. 4, the magnetic tape 21 is scanned in the longitudinal direction of the magnetic tape 21 from the right to the left in FIG.
R ₁ scans the recording track T ₁ of the magnetic tape 21, and the resistance value of the magnetoresistive element MR ₁ changes in response to the information recorded on the recording track T ₁ , so that the voltage across the magnetoresistive element MR ₁ Changes. This voltage change is applied to the coupling capacitor 4 of the regenerative amplifier circuit 3 via the transistor Qa in the ON state, amplified in the regenerative amplifier circuit 3 in the same manner as in the conventional example of FIG. Is input to the input terminal of the first channel of.

Hereinafter, the same operation is performed in the reproduction head circuit 1 and the reproduction amplifier circuit 3 of the second channel # 2 to the twentieth channel # 20, and the forward path magnetoresistive element of the second channel # 2 to the twentieth channel # 20. The voltage change detected by MR ₂ to MR ₂₀ is amplified by the reproduction amplifier circuit 3 of each channel and then input to the input terminal of each channel of the analog multiplexer 7. The signals of the respective channels input to the analog multiplexer 7 are time-divisionally selected and output from the output terminals to the A / D converter 8, and the digital waveform equalizing circuit 9 and the digital waveform equalizing circuit 9 are output in the same manner as in the conventional example of FIG. The audio signal reproduced from the magnetic tape 21 is output to the output terminal 14 via the PLL circuit 10, the digital demodulation circuit 11, the digital signal processing circuit 12, and the D / A converter 13.

Further, when performing the return path reproduction, the switches 2a and 2b are switched to the R side. This causes the base of transistor Qa to be grounded to earth via switch 2a, while the transistor Qa
A positive voltage of the DC voltage source B is applied to the base of Qb via the switch 2b, so that the transistor Qa is turned off, the transistor Qb is turned on, and the constant current source CS
_A constant current flows from ₁ to the magnetoresistive element MR ₁ ′ through the transistor Qb.

Similar to the conventional example shown in FIG.
When the magnetic resistance element MR ₁ ′ is moved in the direction from the left to the right in FIG. 4 in the longitudinal direction of 21, that is, the direction 24b opposite to the direction of the forward reproduction, the magnetoresistive element MR ₁ ′ is recorded on the recording track T of the magnetic tape 21. The resistance value of the magnetoresistive element MR ₁ ′ changes in response to the information recorded on the recording track T ₁ ′ by scanning ₁ ′, and thus the voltage across the magnetoresistive element MR ₁ ′ changes.

This voltage change is applied to the coupling capacitor 4 of the regenerative amplifier circuit 3 via the transistor Qb in the ON state, and after being amplified in the regenerative amplifier circuit 3 in the same manner as in the case of the forward path regeneration, the analog multiplexer 7 It is input to the input terminal of channel # 1.

Hereinafter, the same operation is performed in the reproducing head circuit 1 and the reproducing amplifier circuit 3 of the second channel # 2 to the twentieth channel # 20. Further, the operation from the analog multiplexer 7 to the output terminal 14 is the same as that in the forward path reproduction.

In the above embodiment, the magnetoresistive element requires a total of 40 elements for the forward path reproduction and the backward path reproduction, but as shown in the circuit of FIG. 1, the constant current source and the reproduction amplifier circuit 3 are conventional examples. Only half of 20 circuits is required. Here, when the constant current source for 20 channels capable of forward and backward reproduction, the switching circuit by the switching transistors Qa and Qb, and the reproduction / amplification circuit 3 are realized by a one-chip integrated circuit,
Since the switching circuit using the switching transistors Qa and Qb is very small compared to the reproduction amplifier circuit 3, it is compared with the circuit for 40 channels for the forward reproduction and the return reproduction of the reproduction head circuit 30 and the reproduction amplification circuit 3 of the conventional example. It can be realized by halving the chip size. As a result, the chip area is almost halved, and along with this, the yield of ICs is improved and the cost is reduced. Also, the number of constant current sources is half that of the conventional example, and the overall power consumption is reduced. The transistors Qa and Qb require a low-noise switching transistor because the output of the magnetoresistive element is a few tens of microvolts to 1 mV, which is a very small signal. IC can be easily made.

Although the number of one-way tracks of the magnetic tape 21 is set to 20 in the above embodiments, the present invention provides a reciprocal reproduction type magnetic recording / reproducing apparatus for reproducing the magnetic tape 21 having a natural number of one-way tracks other than that. Applicable.

Further, although the reproducing circuit of the reciprocating reproducing type digital magnetic recording / reproducing apparatus has been described, the present invention can be easily applied to the reciprocating reproducing type analog magnetic recording / reproducing apparatus.

Furthermore, although the case where the magnetic tape 21 is used as the magnetic recording medium has been described, the present invention can be applied to the case where another type of magnetic recording medium is used.

[Effects of the Invention] As described in detail above, according to the present invention, the constant current source is provided with the switching means for selectively switching the forward reproduction magnetic resistance element and the backward reproduction magnetic resistance element to connect the constant current source. Also, by commonly using the reproduction amplifier circuit in the forward reproduction and the backward reproduction, the circuit scale can be reduced and the power consumption can be reduced as compared with the conventional example, and the reciprocation of the magnetic recording medium having many tracks can be performed. There is an advantage that the reproducing magnetic head circuit capable of reproduction can be modularized.

[Brief description of drawings]

FIG. 1 is a block diagram of a reproducing circuit of a reciprocating reproducing type digital magnetic recording / reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of a reproducing circuit of a conventional digital magnetic recording / reproducing apparatus, and FIG. 2A is a diagram showing the positional relationship between the recording track of the magnetic tape and the magnetoresistive element of the reproducing head in the forward reproduction when the magnetic recording / reproducing apparatus of FIG. 2 is used, and FIG. FIG. 4 is a diagram showing the positional relationship between the recording tracks of the magnetic tape and the magnetoresistive elements of the reproducing head in the backward path reproduction when the magnetic recording / reproducing apparatus is used. FIG. It is a figure which shows the arrangement | positioning relationship with a recording track. 1 ... Playback head circuit, 2a, 2b ... Outgoing path return / return path playback switch, 3 ... Playback amplification circuit, CS ₁ ... Constant current source, B ... DC voltage source, MR ₁ ... MR _20. Magnetoresistive element for reproduction, MR ₁ '... MR ₂₀ ' ... Magnetoresistive element for return path, Qa, Qb ... Switching transistor.

Claims (1)

[Claims] 1. A forward-reproducing and backward-reproducing magnetic resistance element, which is provided so as to scan forward and backward tracks on a magnetic recording medium, and a constant current source which supplies a current in common to the magnetoresistive element. A reciprocal reproducing magnetic recording / reproducing apparatus comprising: switching means for selectively switching between the forward reproducing magnetic resistance element and the backward reproducing magnetic resistance element and connecting to the constant current source.