JP2816558B2 - Magnetic reproducing device and combination head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic reproducing apparatus and a combination head for reproducing recorded information by tracing a recording medium using a reproducing head.

[Prior Art] As one of magnetic reproducing apparatuses, a part of a conventionally known helical scan type VTR, particularly, for example, a helical scan type VTR for performing high-density narrow-track recording, has a recording track. A so-called DTF (Dynamic Track Following) system is employed in order to obtain an appropriate reproduction output signal even when the position traced by the reproduction head is relatively slightly shifted.

In the DTF system, the position of the reproducing head disposed on the head drum is controlled during rotation of the drum so that the reproducing signal output level of the reproducing head becomes constant. Specifically, for example, a reproducing bed is attached to the tip of a bimorph plate having a structure in which two piezoelectric elements are sandwiched between three electrodes, and a voltage proportional to the magnitude of the displacement of the reproducing head is applied. In this configuration, the head position is controlled by detecting the amount and direction of deviation from the track during reproduction, extracting a voltage proportional thereto, and driving the bimorph plate displacement means.

[Problems to be Solved by the Invention] A conventional technique for finely controlling the position of the reproducing head as described above.
The DTF method has the following drawbacks, so it cannot be applied to general consumer VTRs, and has been adopted only in some commercial equipment.

In order to displace the head position on the head drum, a complicated structure such as a piezoelectric element, a mechanism for enlarging the displacement of the piezoelectric element, a power supply means to a rotating body such as a microbrush, and a piezoelectric element control circuit including hysteresis correction of the piezoelectric element is required. It will be expensive.

Since it has a mechanical sliding portion such as a micro brush or a displacement mechanism, there are problems such as reliability.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a magnetic reproducing apparatus capable of obtaining an appropriate reproduction signal even with a bent recording track with a simple configuration.

Means for Solving the Problems In order to achieve the above object, the invention of claim 1 of the present application has a head gap width smaller than the track width of a recording track, and shifts in the track width direction. A first head gap group provided with a plurality of gap portions having the same azimuth; and a first head gap group shifted in the head scan direction with respect to the first head gap group. A plurality of gap portions having a head gap width smaller than a track width, disposed between the plurality of gap portions of the first head gap group in the track width direction, and having the same azimuth as the azimuth; A reproducing head unit provided with a second gap group, an amplifier circuit for amplifying an output from each of the gap portions, A delay circuit for correcting a reproduction output time from one head gap group, and a multiplexer for synthesizing an output from each of the gap portions via the amplification circuit and the delay circuit. The magnetic reproducing apparatus according to claim 2, wherein the plurality of magnetic recording apparatuses have a head gap width smaller than the track width of the recording track, and are arranged to be shifted in the track width direction and have the same azimuth. A first head gap group including a gap portion;
The first head gap group is arranged shifted in the head scanning direction with respect to the first head gap group, has a head gap width smaller than the track width of the recording track, and has a head gap width in the track width direction. A combination head is provided between a plurality of gap portions, and a second gap group including a plurality of gap portions having the same azimuth as the azimuth is provided.

[Operation] According to the above configuration, when reproducing the recording track, the reproduction output from the gap group of the combination head is synthesized by the delay circuit and the multiplexer, so that the output between the recording track and the head trajectory is formed. However, even when there is a relative bend, a good reproduction signal can be obtained by sharing each head gap.

Therefore, compared to the conventional DTF system, there is no mechanical movable part, so that the reliability is extremely high, and the cost can be reduced.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing the structure of a reproducing combination head according to an embodiment of the present invention. The combination head for reproduction (hereinafter referred to as a head) is a head composed of a so-called yoke type MR (magnetic resistance) element.
On head substrates 101 and 102 made of Ni-Zn ferrite also serving as a lower yoke, a bias line 103 made of a bias layer is formed via an insulating layer.

As shown in FIG. 8, the MR element 105
A bias line 103 for applying a predetermined bias magnetic field ΔH is provided to obtain a linear response characteristic because of having a characteristic indicating a power change, and a bias magnetic field ΔH is applied by applying a DC current to the bias line 103. Can be obtained. The MR element 105 is provided on the base via an insulating layer, and is guided by conductors 107 and 108 to an amplification circuit 109 as a reproduction amplifier provided on the head base 101 via a coupling capacitor 110. 104 and 106 are upper yokes, which are arranged on the MR element 105 via an insulating layer.

Now, when a magnetic field is induced in the head gap portions G1 to G5, MR
A change in the resistance value of the element 105 occurs and is input to the amplifier circuit 109. Group of head gap G1, G3, G5 and head gap G2, G4
Are arranged with a gap group interval Δd in the head scanning direction and offset in a positional relationship such that they overlap with each other in the track width direction.

FIG. 2 shows the combination head for reproduction shown in FIG.
FIG. 3 is a configuration diagram of a head unit to be disposed on a rotating drum of a VTR, provided with a predetermined azimuth angle θ with respect to a head scanning direction, and provided with a reinforcing member made of glass, ferrite, or the like in a peripheral portion. Have been.

As shown in FIG. 7, the recording track patterns of the VTR are arranged so as to resist each other and have different azimuth recording heads.
The patterns 71 and 72 are recorded as a pattern as shown in FIG.

When reproducing the recording track, the recording track is reproduced by reproduction head groups 73 and 74 which are arranged on a rotating drum and made of azimuth corresponding to the recording heads 71 and 72. As described above, the plurality of head gap widths of the reproduction head groups 73 and 74 correspond to the recording track width, and the reproduction output is obtained from the composite output from the plurality of heads. That is, when the relative position between the reproducing head group and the recording track TWR is in a relationship as shown in FIG. 3, the recording track TW
Due to the azimuth of R, the reproduced output from each of the head gaps G1 to G5 has an output level at a timing as shown in FIG. At this time, head gap G
The output from the group of 1, G3, G5 and the output from the group of head gaps G2, G4 are obtained by shifting by the time Δt corresponding to the gap distance Δd. In FIG. 3, the head gap G1
4 shows that the reproduction output level is not obtained as shown in FIG. 4 because of deviation from the track TWR.

FIG. 5 is a circuit diagram showing a main configuration of a reproducing circuit for obtaining a reproduced output signal by synthesizing a resistance change of each head gap composed of an MR element. Outputs from head gaps G3 and G5 correspond to time Δt. After passing through the delay circuit 51, the outputs from the head gaps G2 and G4 can be obtained by the multiplexer 52.

In FIG. 4, the case where the number of gaps is five is described. However, as shown in FIG.
₁ ,... MR _n may be used. Each head gap G1, G2…
The resistance changes of the heads MR ₁ , MR ₂ ,... Corresponding to... Are applied to the input stage of the amplifier circuit 109 via the coupling capacitor 110 for cutting the DC component. Reference numeral 55 identifies the output level of the reproducing amplifier, that is, the output level of the amplifier circuit 109, and sets the signal to the multiplexer 52 in the subsequent stage so as not to be sent out when the output level does not reach a predetermined level.

The delay circuit 51 for the delay amount between the head gap groups is as described above.

The combined output obtained by the multiplexer 52 can be obtained as a digital output signal via the A / D converter 56 and the demodulation circuit 57.

[Effects of the Invention] As described above, according to the present invention, even when a recording track and a reproducing head are relatively displaced and in a reproducing state, a reproducing combination head including a plurality of gaps, a delay circuit, A good reproduction output can always be obtained with the multiplexer. As before
Since it does not require a movable part such as a DTF head, it can be applied to a consumer VTR because it is not only highly reliable but also inexpensive in terms of cost, and is extremely industrially effective.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a reproducing combination head according to an embodiment of the present invention, and FIG. 2 is a head for disposing the reproducing combination head of FIG. 1 on a rotating drum of a VTR. FIG. 3 is a diagram showing the relative positional relationship between a combination head for reproduction and a recording track according to the present embodiment, and FIG. 4 is a diagram showing the respective positions when the combination head and the tape are positioned at the positions shown in FIG. FIG. 5 is a diagram showing a reproduction output level from a head gap and an output timing. FIG. 5 is a circuit showing a main configuration of a reproduction circuit for obtaining a reproduction output signal by synthesizing a resistance value change of each head gap composed of an MR element. FIG. 6, FIG. 6 is a diagram showing a state of a recording track, and FIGS. 7 (a) and 7 (b) are plan views showing the relationship between a recording head, a reproducing head, and a tape arranged on a rotating drum, and a side view. , FIG. 8 is a diagram showing characteristics of change in resistance output to input magnetic field of the MR element used for read heads. In the figure. 101, 102: Head substrate 103: Bias line 104, 106: Yoke 105: MR element 107, 108: Conductor 109: Amplifier circuit 110: Coupling capacitor G1, G2, G3, G4, G5: Head gap MR ₁ …… MR _2n : Head composed of MR elements 71,72: Head unit for recording 73,74: Head unit for reproduction 51: Delay circuit 52: Multiplexer 55: Reproduction level identification circuit 56: A / D converter 57: Demodulation circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 5/02 G11B 5/37

Claims (2)

(57) [Claims] 1. A first head gap having a head gap width smaller than the track width of a recording track, and having a plurality of gap portions which are arranged shifted in the track width direction and have the same azimuth. And a first head gap group, the first head gap group being shifted in the head scanning direction, having a head gap width smaller than the track width of the recording track, and the first head being disposed in the track width direction. A reproducing head unit provided between the plurality of gaps of the gap group and a second gap group including a plurality of gaps having the same azimuth as the azimuth; and An amplification circuit for amplifying the output of the first head gap group; a delay circuit for correcting a reproduction output time from the first head gap group; Magnetic reproducing apparatus, characterized in that the via the serial amplifier circuit and the delay circuit and a multiplexer for combining the outputs from the gap portion. 2. A first head gap having a head gap width smaller than the track width of a recording track, being provided shifted in the track width direction, and having a plurality of gap portions having the same azimuth. A first head gap group and a head gap width smaller than the track width of a recording track; and the first head gap in the track width direction. A combination head provided between a plurality of gaps of a gap group and a second gap group including a plurality of gaps having the same azimuth as the azimuth.