JPS623403A - Rotary head type magnetic recording device - Google Patents

Abstract

PURPOSE:To make constant the coil electric current by constituting the device of the first rotary transformer to supply the recording amplifier and the amplifying recording signal to the head provided at the drum rotar side, the second rotary transformer where the primary side coil is serially connected to the head coil and the circuit to negative-feed back toe secondary side output to the amplifier. CONSTITUTION:A head coil electric current is fed back through the second rotary transformer to a recording amplifier, and as a whole, the negative feeding-back amplifying system is constituted. Namely, the head coil electric current is supplied to the primary side of the second rotary transformer, and the output is negative-fed back through a feeding-back circuit to a recording amplifier. Concretely speaking, a recording signal 1 is amplified by a recording amplifier 2. supplied through the first rotary transformer 3 to a head coil 4, an electric current IH to flow here is supplied to the primary side coil of the second rotary transformer 5, and the secondary side output is negative-fed back through a heeding back circuit 6 to the amplifier 2. Thus, the change of the coil electric current due to the variance of the coil impedance is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotating head type magnetic recording device, and particularly to improving the transmission characteristics of recording signals to the head in the device.

[Conventional technology]

Figure 3 shows the transmission form of a recording signal to the head in a conventional rotary head type magnetic recording device, such as a VTR. A portion 8 surrounded by a dashed line is a portion included on the drum rotor side. In the following description, the windings on the drum/rotor side 8 of the rotary transformer will be referred to as the "primary side", and the windings on the drum/stator side, that is, the stationary side of the main body, will be referred to as the "secondary side".

Next, the operation will be explained. Recording signal 1 is recording amplifier 2
and is supplied to the head coil 4 via the rotary transformer 3.

Figure 4 shows this system as a transfer function block diagram, with the recording signal 1 being V, (S) and the recording amplifier 2 being C.
O(S), the rotary transformer 3 is a + (S), and the impedance of the head coil 4 is 1(S), then the head coil current is 1. <S) is expressed by the following formula.

...(1) Here, as is clear from the equivalent circuit calculation, the transmission gap number G+(S) of the rotary transformer 3 also depends on the head coil impedance ZW(S), and this C
, (S) and ZI4(S) are the head coil current I)
dominates l(S).

By the way, in general, head coil impedance has large variations in the parameters that govern it. For example, in systems such as home VTRs that are premised on mass production, this variation in head coil impedance becomes a big problem. In such a conventional transmission form, even if the variations in the parameters of the recording amplifier 2 and rotary transformer 3 are suppressed to a sufficiently small level, the head coil current IN(S) (as shown in equation 11) is equal to the head coil impedance ZM( It can be seen that it is greatly influenced by S).

[Problem that the invention seeks to solve]

As described above, the conventional recording signal transmission format has a problem in that the current supplied to the head coil changes due to variations in the head coil impedance.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a rotating head type magnetic recording device that can supply a constant head coil current even if there are variations in head coil impedance.

[Means for solving problems]

The rotary head type magnetic recording device according to the present invention has a negative feedback amplification system as a whole by feeding back the head coil current to the recording amplifier via the second rotary transformer.

[Effect]

In this invention, the head coil current is supplied to the primary side of the second rotary transformer, and the output of this rotary transformer is negatively fed back to the recording amplifier via the feedback circuit.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 5 is a second rotary transformer whose primary side is supplied with head coil current, and 6 is a recording amplifier 2 that amplifies or attenuates the output of this second rotary transformer 5, or gives it a frequency characteristic. This is a feedback circuit for feeding back and configuring a negative feedback amplification system as a whole. The rest of the configuration is the same as that shown in FIG.

Next, the effects will be explained.

A recording signal 1 is amplified by a recording amplifier 2 and supplied to a head coil 4 via a first rotary transformer 3. The current IN flowing through the head coil 4 is supplied to the primary winding of the second rotary transformer 5. This second
Two side outputs of the rotary transformer 5 pass through a feedback circuit 6 and are negatively fed back to the recording amplifier 2.

FIG. 2 shows this system as a transfer function block diagram, where the primary input impedance of the second rotary transformer 5 is Zi (S), and the transfer function of the second rotary transformer 5 is Gz ( S).

If the transfer function of the feedback circuit 6 is H(S), the head coil current In(S) is expressed by the following equation.

C0(S) ・G, (S) ・□ 1゜Zy (S) + Zi(S) ... (2) (The second term of the denominator of the equation on the first line is GL (S) Here, GL (S) is a -cyclic transfer function, and based on the general design method of negative feedback amplification systems, l Gt (S) l>>l in the signal frequency band to be handled.
...(3), the equation (2) becomes ...(4), and a head coil current In(s) that does not depend on the head coil impedance Z)+(,S) can be obtained.

This is nothing but the basic principle that in a negative feedback amplification system, its transmission characteristics are controlled by the characteristics of the feedback path.

Therefore, if the rotary transformer is appropriately designed and H(S) of the feedback circuit 6 is designed in consideration of its characteristics, the head coil current characteristics can be freely controlled by H(S).

Furthermore, according to this embodiment, nonlinear distortion, which is a characteristic of negative feedback amplification systems, is improved, and signal transmission quality is significantly improved.

In addition, in the above embodiment, it was shown only as a recording device, but
If it is also used for reproduction, it is sufficient to provide a mechanism for switching and controlling the signal transmission path.For example, the secondary side of the rotary transformer 3 may be separated from the recording amplifier 2 and connected to a reproduction amplifier (not shown). have been realized in various forms in home VTRs, and it is clear that the effects of the present invention can be obtained even in this case.

〔Effect of the invention〕

As described above, according to the rotary head type magnetic recording device according to the present invention, the head coil current is supplied to the primary side of the second rotary transformer, and negative feedback is applied to the recording amplifier via the rotary transformer. With this structure, changes in head coil current due to variations in head coil impedance can be suppressed, and nonlinear distortion can also be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a rotary head type magnetic recording device according to an embodiment of the present invention, FIG. 2 is a transfer function block diagram of the device, FIG. 3 is a block diagram of a conventional device, and FIG. 4 is a block diagram of a conventional device. FIG. 3 is a transfer function block diagram. 2... Recording amplifier, 3... First rotary transformer, 4... Head, 5... Second rotary transformer, 6... Feedback circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A recording amplifier that amplifies a recording signal, a first rotary transformer that supplies the recording signal amplified by the recording amplifier to a head mounted on the drum rotor side, and a primary winding of the head. A rotary head type magnetic recording device comprising: a second rotary transformer connected in series to a coil; and a feedback circuit that negatively feeds back a secondary output of the second rotary transformer to the recording amplifier. .