JPS62139104A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve a general transmission characteristic without adjustment by negatively feeding back the output of a desired transmission circuit to an input side through a contrast character transmission circuit. CONSTITUTION:Since the characteristic of a demodulation circuit 33 in a recording system 30 is the same as that of a demodulation circuit 7 in a reproduction system 5, the output signal of the demodulation circuit 7 in the reproduction system 5 becomes the same as that of the demodulation circuit 33 in the recording system 30 by assuming that the magnetic heads 4 and 6 of both recording and reproduction systems have ideal conversion characteristics. In order to correct the overall distortion characteristic of a magnetic recording and reproducing device, the output of the demodulation circuit 33 in the recording system 30 is corrected. Where the overall distortion of a modulation circuit 3 and the demodulation circuit 33 and a propagation function F are DELTAG (DELTAG<<1) and H=beta (beta>>1), respectively, the propagation function F covering from the output of a preemphasis circuit 2 and that of the demodulation circuit 33 approximates to 1+DELTAG/(1+beta). As beta>>1, the right side can be neglected. Thus the distortion can be improved without adjustment.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a magnetic recording/reproducing device.

[Summary of the invention]

The present invention provides magnetic recording by providing a recording system with a transmission circuit having characteristics contrasting with that of the desired transmission circuit, and feeding back the output of the desired transmission circuit through the transmission circuit having contrasting characteristics. This improves the overall transmission characteristics of the playback device without any adjustment.

[Conventional technology]

Conventional video tape recorder (hereinafter abbreviated as VTR)
As shown in FIG. 3, the video signal is sent from the input terminal IN of the recording system 11J to the frequency modulation circuit (3) via the pre-emphasis circuit (2) for improving high frequency S/N.
supplied to The output of the frequency modulation circuit (3), that is, the modulated high frequency (FM-1 (F) signal) is transmitted to the recording magnetic head (4).
) is recorded on the magnetic tape T. The FM-R, F" signals recorded on the tape T are reproduced by the reproducing magnetic head (6) of the reproducing system (5) and demodulated by the demodulator (7). The demodulated output signal of the demodulator (7) is led out to the output terminal OUT via the de-emphasis circuit (8).

For example, as shown in FIG. 4A, the pre-emphasis circuit (2) connects the emitter of the transistor Uυ to ground via series-connected resistors (121 and 03), and connects a capacitor I in parallel to the resistor 03. It consists of

In addition, the de-emphasis circuit (8) connects a load resistor Qz and (23) connected in series to the collector of a transistor (21J), as shown in FIG. 4B, for example.
Resistor CI! 31'L capacitor system connected in parallel, or as shown in FIG. 4C, the transistor CI'
It is constructed by connecting a series circuit of a resistor Masuda and a capacitor (5) in parallel to a load resistor Q9 connected to the collector of 1).

As is well known, the pre-emphasis circuit (2) and the de-emphasis circuit (8) have contrasting transmission characteristics that are opposite to each other, and the frequency modulation circuit (3) and the demodulation circuit (also known as the sword) have opposite transmission characteristics. Because they have contrasting characteristics and functions, regeneration systems (5
) is the same as the input video signal in principle.

[A far point while the invention is trying to solve]

However, in actual VTRs, the modulation circuit (3) and demodulation circuit (7) each have linear and non-linear amplitude distortion and phase distortion, so the input video signal is not reproduced correctly and the reproduced image is distorted. Quality deteriorates.

For this reason, in conventional VTRs, distortion correction is performed on the output side of the demodulation circuit (7) in order to keep the differential gain (DG) and differential phase (DP) of the reproduced video signal within tolerance values. The problem was that it was complicated.

Furthermore, in the combination of the pre-emphasis circuit and de-emphasis circuit as shown in FIGS. 4A and 4B, the values of each resistor and capacitor are R12+R13.

As R22t R23 and C14r C24, ■t1
2~R221R13 SirR23IC14'i''024, or in the case of a combination of a pre-emphasis circuit and a de-emphasis circuit as shown in A and C of the same figure, in order to have the characteristic of the de-emphasis circuit inverse to that of the emphasis circuit, It is necessary to adjust the time constant, but in order to perform this adjustment using fixed resistors and capacitors, it is necessary to select circuit components and use multiple components connected in series or in parallel. However, there was a problem in that adjustment was troublesome.

In view of this point, an object of the present invention is to provide a magnetic recording/reproducing device that can improve overall transmission characteristics without adjustment.

[Failure to solve the problem]

The present invention provides a magnetic recording/reproducing device having transmission circuits with contrasting characteristics in the recording system and reproduction system, respectively, in which the recording system is provided with a transmission circuit having characteristics contrasting with that of the desired transmission circuit, and the transmission circuit is This is a magnetic recording/reproducing device in which the output of a desired transmission circuit is negatively fed back to the input side via a transmission circuit with characteristics.

[Effect]

According to this configuration, the desired characteristics of the transmission circuit can be improved without adjustment due to negative feedback.

〔Example〕

An embodiment of the magnetic recording/reproducing apparatus according to the present invention will be described below with reference to FIG.

FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals and redundant explanation will be omitted.

In FIG. 1, ■ indicates the recording system as a whole, and a first subtraction circuit 6υ is inserted between the pre-emphasis circuit (2) and the frequency modulation circuit (3), and the first subtraction circuit 6υ is inserted between the pre-emphasis circuit (2) and the frequency modulation circuit (3). The output is supplied to the subtraction side input terminal of the second subtraction circuit r33. The related part is a demodulation circuit, which uses a semiconductor integrated circuit having the same configuration as the demodulation circuit (7) of the reproduction system (5) and has the same characteristics. The FM-RF ratio output of the frequency modulation circuit (3) is supplied to this demodulation circuit (3), and the output of the demodulation circuit (g) is supplied to the second subtraction circuit G2. The output of the second subtracting circuit 0'4 is supplied to the subtracting side input terminal of the first subtracting circuit 6υ via a full range filter (b) to form a feedback loop. The rest of the structure is the same as the conventional device shown in FIG. 3 above.

The operation of this embodiment is as follows.

As mentioned above, the characteristics of the demodulation circuit example of the recording system (7) are the same as the characteristics of the demodulation circuit (7) of the reproduction system +51, so both the recording and reproduction magnetic heads (4) and (6) are ideal. The output signal of the demodulation circuit (7) of the reproduction system (5) and the output signal of the demodulation circuit (c) of the recording system (to) are the same as those having conversion characteristics. Therefore, in order to correct the overall distortion characteristics of the magnetic recording/reproducing apparatus, it is sufficient to correct the distortion characteristics of the output of the demodulation circuit (g) of the recording system (2).

In FIG. 1, if the transfer functions of the frequency modulation circuit (3) and demodulation circuit example are G and G2, respectively, and the transfer function of the whole range filter (b) is H, then demodulation is performed from the output of the pre-emphasis circuit (2). The transfer function F to the output of the circuit (g) is expressed as the following equation (1).

Now, the total distortion of the modulation circuit (3) and demodulation circuit is expressed as ΔG(
If ΔG×1) and H=β(β〉1), then G1・G
2-1+Δq, and the fi1 formula can be rewritten as follows.

As mentioned above, since β>1, the second right-hand side of equation (2)
term can be ignored.

The second term on the right side of equation (2) is the total distortion component of this embodiment, and it will be clear from this that the distortion can be improved without adjustment by this embodiment.

In addition, in this embodiment, if the whole range filter is replaced with a low-pass filter, low-frequency distortion (especially linearity) can be improved, and fluctuations in the carrier wave of the modulation circuit (3) can be suppressed.

Next, another embodiment of the magnetic recording/reproducing apparatus according to the present invention will be described with reference to FIG.

The structure of another embodiment of the present invention is shown in FIG. In FIG. 2, parts corresponding to those in FIG. 3 are designated by the same reference numerals and redundant explanation will be omitted.

In Figure 2, (4G indicates the recording system as a whole,
A first subtraction circuit 0υ is inserted between the pre-emphasis circuit (2) and the input terminal IN.
The video signal is supplied to the subtraction side input terminal of the second subtraction circuit (42). (43 is a de-emphasis circuit, which has the same configuration as the de-emphasis circuit (8) of the reproduction system (5), The output of the pre-emphasis circuit (43) is supplied to the de-emphasis circuit (03), and the output of the de-emphasis circuit (43) is supplied to the second subtraction circuit (6). The output of the circuit (6) is supplied to the subtraction side input terminal of the first subtraction circuit 0υ via the full range filter 04) to form a feedback loop.

The rest of the structure is the same as the conventional device shown in FIG. 3 above.

The operation of this embodiment is as follows.

As mentioned above, the recording system (4CJ de-emphasis circuit (
The characteristics of l13 are the de-emphasis circuit (8) of the reproduction system t57.
), the output signal of the de-emphasis circuit (8) of the reproduction system (5) and the output signal of the de-emphasis circuit (c) of the recording system are approximately the same. Therefore, in order to correct the overall frequency characteristics of the magnetic recording and reproducing apparatus, it is sufficient to correct the deviation in the frequency characteristics of the output of the de-emphasis circuit of the recording system (41).

In Figure 2, the transfer functions of the pre-emphasis circuit (2) and de-emphasis circuit (c) are expressed as G3 and G3, respectively.
4, and let H be the transfer function of the whole range filter (goods), then
The transfer function F from the input terminal IN to the output of the de-emphasis circuit (c) is expressed as the following equation (3).

Now, the difference in the time constants of the pre-emphasis circuit (2) and the de-en-7 assist circuit (c) is expressed as ΔG (ΔG × 1
) and H=β (β>1), then G3・G4=1+
ΔG, and equation (3) can be rewritten as follows.

As mentioned above, since β>1, the second right-hand side of equation (4)
term can be ignored.

The second term on the right-hand side of equation (4) is simply the deviation component of the overall frequency characteristics of this example, and it is clear from this that the frequency characteristics can be improved without adjustment by this example. Become.

In this embodiment, it is possible to improve a specific frequency region by replacing the whole range filter with a transmission circuit having appropriate frequency characteristics.

〔Effect of the invention〕

As described in detail above, according to the present invention, negative feedback is applied to a desired transmission circuit of the recording system by a transmission circuit whose characteristics are contrasting with that of the desired circuit, so that the overall characteristics are improved without any adjustment. A magnetic recording/reproducing device can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of one embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a block diagram showing the configuration of another embodiment of the present invention, and FIG. 3 is a conventional magnetic recording/reproducing apparatus. FIG. 4 is a block diagram illustrating an example of the configuration of the main parts of the present invention, and FIG. 4 is a wiring diagram for explaining the present invention. (1), (7), QQ is a recording system, (2) is a pre-emphasis circuit, (3) is a frequency modulation circuit, (5) is a reproduction system,
(The second sword is a demodulation circuit, +8+, (4:l is a de-emphasis circuit.

Claims (1)

[Scope of Claims] 1. In a magnetic recording/reproducing device having transmission circuits with contrasting characteristics in each of the recording system and the reproduction system, the recording system is provided with a transmission circuit having characteristics contrasting with those of the desired transmission circuit. , A magnetic recording/reproducing device characterized in that the output of the desired transmission circuit is negatively fed back to the input side via the transmission circuit with contrasting characteristics. 2. The magnetic recording and reproducing apparatus according to claim 1, wherein the recording system is provided with a demodulator, and the output of the frequency modulator is negatively fed back to the input side via the demodulator. 3. The magnetic recording and reproducing apparatus according to claim 1, wherein the recording system is provided with a de-emphasis circuit, and the output of the pre-emphasis circuit is negatively fed back to the input side via the de-emphasis circuit.