JPS62248110A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the amplitude frequency characteristic and the phase frequency characteristic of a reproduced waveform by setting a reflectance of a delay circuit at a non-matching terminal with respect to an input signal to one or below so as to compensate the phase distortion of a reproducing signal. CONSTITUTION:The reproducing signal 1 from a recording medium is inputted to a delay line 2 via a matching resistor 3 to obtain a waveform whose amplitude only is lowered to the signal 1. The reflectance of the reproduced waveform reaching the non-matching terminal of the delay line to be returned to the matching side is set to the unity or below. Further, the value of the matching resistor 3 is kept equal to the characteristic impedance of the delay line 2. After signals c, l among signals b, c, l are added at the matching terminal of the delay line 2, the amplitude is adjusted by an attenuator 6. Further, the result is subtracted from a signal (b) by a subtraction circuit 5 and the result rises and a sharp pulse (f) having a small trailing time is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic recording/reproducing apparatus, and particularly to a magnetic recording/reproducing apparatus having a reproduction waveform equalization circuit suitable for a rotary head type digital audio tape recorder.

(Prior Art) As for the waveform equalization circuit of conventional magnetic recording and reproducing apparatuses, a transversal filter using a delay line is often used as described in Japanese Patent Publication No. 3603/1983.

The waveform equalization circuit described in this publication is configured by minimizing the number of delay lines and the delay time of the delay lines used in the Tokunsual filter, which reduces the circuit scale and the cost of the circuit. It is very good in this respect.

Furthermore, in this example, the relationship between the frequency and phase of the recording medium and the head (hereinafter referred to as the phase frequency characteristic) is expressed as If you want to do this, this is the most suitable circuit configuration. Here, the angular frequency ω that provides the maximum gain.

Let the delay time of the delay line be τ.

It becomes ωo3π/τ. However, no consideration has been given to the case where the phase frequency characteristics of the recording medium and the head are non-linear.

Next, the case where the phase frequency a characteristic is non-linear and the reproduced waveform has phase distortion is described in Japanese Patent Laid-Open No. 58-3117. This known example attempts to improve only the rising portion of the reproduction pulse, and does not take into account the situation where the reproduction pulse has a wide tail at the rising and falling edges.

(Problem to be solved by the invention) In general, in a device that handles high-frequency reproduction signals, such as a rotating head type magnetic recording device, resonance occurs in the reproduction frequency characteristics due to the inductor 7 of the rotating head and the input zero t of the reproduction preamplifier. , and the phase frequency characteristics become nonlinear. Therefore, the obtained reproduced waveform has phase distortion, and according to the waveform equalization circuit disclosed in the Bulletin of Japanese Patent Publication No. 54-3603, the amplitude-frequency a characteristic of the reproduced waveform is improved, but the phase distortion I can't improve at all! There was a problem that there was no I.

Furthermore, the device described in the above-mentioned Japanese Patent Application Laid-Open No. 58-3117 attempts to improve only the rising portion of the reproduced waveform of a magnetic recording/reproducing device when there is phase distortion. There is a problem in that it does not correct both of the falling edges. In addition, this conventional device has two speeds fJf at which the magnetic storage device reads recorded signals, and does not take into account the case where two central angular frequencies are required for amplitude emphasis of the waveform equalization circuit. There was a problem in that it could not be applied to magnetic recording devices with variable speeds.

A first object of the present invention is to improve not only the amplitude frequency characteristics (but also the phase frequency characteristics) of the reproduced waveform by applying the circuit described in the aforementioned Japanese Patent Publication No. 54-3603 Bulletin 1e.

A second object of the present invention is to correct both the rise and fall of the reproduced waveform of a magnetic recording and reproducing device, completely correct one phase distortion, and to create a magnetic memory that has two or more read speeds f! 1
The aim is to be able to respond to jIl.

(Means for Solving the Problem) The first object is to terminate the non-matching side terminal of the delay line used in the circuit described in Japanese Patent Publication No. 54-3.6039 with a resistor to prevent reflection. : This can be achieved by setting it to 481 or less.

Further, the second object is achieved by varying the delay time of the delay line in accordance with the read speed of the magnetic recording device.

(Function) The present invention terminates the non-matching side terminal of the delay line with a resistor and sets the reflectance to less than -v-1, so that feedback is provided to the matching side terminal which is the input side of the 1* delay line. Signal amplitude 8
Ill! to the value corresponding to the reflectance. 11, and by subtracting the signal with delay lτ from the signal obtained by adding the undelayed signal on the input side of the delay line and the feedback signal with delay amount 2τ whose amplitude has been adjusted, the reproduced waveform can be calculated. Not only the amplitude frequency characteristic but also the one-phase frequency characteristic can be improved.

Furthermore, by selecting a delay circuit having two or more delays tz according to the readout speed, the waveform equalization port with the above characteristics can be applied to a magnetic recording/reproducing device having two or more readout speeds. can do.

(Example) The present invention will be explained below using an example. FIG. 1 is a circuit diagram of an embodiment of the present invention.

In the figure, 1 is a reproduction signal obtained from a recording medium, 2 is a delay line for delaying the reproduction signal l by 1 second, and 3 is an impedance matching resistor equal to the characteristic impedance Zo of the delay line 2. 4 is the reflectance at the unmatched terminal of the delay line g4I! II! There is a reflectance g * low resistance, the resistance value is 3 to 5 of the characteristic impedance 2°
It has been doubled.

Further, 6 is an attenuator that adjusts the amplitude of the signal obtained from the matching side of the delay line, and 5 is a subtraction circuit that subtracts the signals obtained from the two terminals on the matching side and the non-matching side of the delay line.

FIG. 2 shows waveforms on the time axis at various parts of the circuit of FIG. 1, and the same symbols as those indicating the waveforms in FIG. 1 are assigned. The time interval T seconds in FIG. 2 is the pulse transmission interval in the magnetic recording device, and the delay time T seconds of the delay line 2 is approximately equal to the pulse transmission interval T seconds.

Next, detailed operation of the circuit shown in FIG. 1 will be explained. The reproduced signal 1 obtained from the recording medium is inputted to the delay line via the matching resistor 38, and a waveform c8 in FIG. 2 is obtained in which only the amplitude is lower than that of the reproduced signal 1.

c and cMKM2O3 impedance +2°.

The resistance value of the reflectance adjustment resistor 4 is expressed by the transmittance mt, which indicates the rate at which the voltage of the signal transmitted from the matching terminal by the R1 delay line 2 is transmitted through the reflectance adjustment resistor 4 and appears. Therefore, the amplitude of the signal shown in FIG. 2 appearing on the non-matching terminal side is mt times larger than cK in FIG.

Furthermore, when the reproduced waveform that reaches the non-matching terminal of the delay line 2 has a reflectance indicating the rate at which the waveform returns to the matching side again, mr is expressed as follows.

), and is transmitted again through the delay line 2 and returned to the matching terminal, obtaining a reproduced waveform delayed by 82τ seconds. At this time, since the value of the matching resistor 3 is equal to the characteristic impedance 2° of the delay line 2, mr becomes 0 in equation (2), and no signal is generated that is reflected at the matching terminal and goes to the non-matching terminal again.

Figure 2 d and @ show the waveforms that are generated at the matching terminal and are delayed by 2τ seconds from the reproduced waveform, ・ is the case where the reflectance mr is set to, for example, 0.6x11', and d is the reflectance The case where the adjustment resistor 4 is left open and mr=1 is shown.

Of the three signals obtained as described above, ble16 in FIG. 2, C and .

Furthermore, the subtraction circuit 5 subtracts the value shown in FIG.
You can get a sharp pulse with small rise and fall times like this.

If time 0 in Figure 2 is the center of the reproduced pulse, then if the reproduced waveform has phase distortion as shown in Figure 2 and the amplitude at time T is smaller than the amplitude at time -T, then is set to a reflectance mr of 81 or less as shown in FIG. 2e. As a result, the reproduced signal is delayed by 2τ seconds.
can be smaller than the amplitude of the signal C in FIG. 2 that does not delay the reproduced signal. Therefore, since the amount of amplitude subtraction at time TK can be set smaller than the amount of amplitude subtraction at time TK, the waveform shown in FIG. do not have.

In general, a reproduced signal obtained from a recording medium has a wide pulse tail with respect to the pulse transmission interval T seconds, as shown in FIG. 2a. Therefore, the pulses interfere with each other. In order to remove this interference, it is necessary to emphasize the high frequencies of the reproduced signal and sharpen the rise and fall of the pulse. However, books! J
According to the waveform equalization circuit of the embodiment, it is possible to emphasize the high frequency range of the reproduced signal and obtain pulses whose amplitude becomes zero at adjacent pulse transmission times as shown in FIG. In order to detect data transmitted from a pulse shaped like N f without error, it is necessary to have left-right symmetry on the time axis with respect to the center of the pulse. However, the reproduced waveform obtained from the recording medium often has phase distortion as shown in FIG. 2a, and the pulses are asymmetrical. According to this embodiment, it is possible not only to emphasize the high frequency range of a pulse wave having phase distortion as shown in FIG. 2, but also to improve the asymmetry of the pulse at the same time.

Next, a case where this embodiment is applied to a rotary head digital audio tape recorder (hereinafter referred to as R-DAT) will be described with reference to FIG. FIG. 3 is a block diagram of the entire R-DAT.

First, when the R-DAT is in a recording state, an audio signal input from the audio input terminal 7 is converted into digital data by the A/D converter 8. Next, the digital data is converted into recording data according to the recording format by the recording signal processing circuit 9, and the recording amplifier 1
The signal is amplified by 0 and recorded on the magnetic tape by the rotary head 11.

Next, when the R-DAT is in the reproduction state, the rotary head 11 scans the magnetic tape and reads recorded data.

After the read data is amplified by a reproducing amplifier 12, interference between pulses is removed by a waveform equalization circuit 13. Furthermore, the clock in the read data is extracted by the data identification circuit 14, and data 10m and '1' are discriminated. Furthermore, this read data is input to the reproduced signal processing circuit 15, and after error detection and correction are performed,
/input converter 16 converts the signal into an audio signal again.

The feature of this application example lies in the waveform equalization circuit 13 in the third rIA. The waveform equalization circuit 13 is generally a circuit-based means for compensating for various losses occurring in the magnetic recording/reproducing circuit 11, and its frequency versus phase characteristic increases in the high range of the reproduced signal band. Further, in the case of a velocity proportional head such as a coil head, it is necessary to provide an integral characteristic by the waveform equalization circuit 13 of ξ in order to cancel out the differential characteristic that occurs during the magnetic recording and reproducing process. Furthermore, in a system such as the KR-DAT that handles relatively high-frequency reproduction signals, the rotary head 11 and the reproduction amplifier 12 produce peaking characteristics, and the reproduction signal contains phase distortion at high frequencies. Therefore, it is necessary to provide the waveform equalization circuit 13 with a frequency versus phase characteristic opposite to the peaking characteristic to cancel out the phase distortion.

@Figure 4 is an example of a specific circuit diagram when an embodiment of the present invention having the above-mentioned features is adopted for waveform equalization circuits 1 and 2) in Figure 3. 018 is an a-woven tape. .

19 is a rotating head, 20 is a rotating transformer, and 2) is a reproducing amplifier.

A reproduction signal read out from the M-woven tape 18 by a rotary head 19 is inputted to a reproduction amplifier 2) via a rotary transformer 20. Next, the reproduction amplifier 2) amplifies the reproduction signal and outputs it to the waveform equalization circuit. The waveform equalization circuit is composed of 22 to 28, where 22 is an integrating circuit for canceling differential characteristics generated in the magnetic recording and reproducing process, and 25 is a delay line with a delay time of f seconds.

23 is a matching resistor equal to the characteristic impedance Zo of the delay line 25, 24 is an attenuator, and 26 is a reflectance adjustment resistor for adjusting the mismatched reflectance of the delay line 25.

27 is a differential amplifier @'6. 28 is an output terminal of the waveform equalization circuit d The operation of the circuit shown in FIG. 4 will be explained. First, the signals recorded on the magnetic tape 18 are read out from the rotary disk 19 by the rotary transformer 2G and the reproduction amplifier 2).

The reproducing waveform output from the reproducing amplifier 2) is sent to the integrating circuit 22.
, and the differential characteristics that occur during the memo recording process are canceled out. Next, the reproduced waveforms are input to the delay line 25 via the matching resistor 23, and as shown in FIG. Obtain a waveform delayed by seconds.

In FIG. 4, portions where waveforms that echo the waveforms in FIG. 2 are obtained are given the same reference numerals as those indicating the waveforms in FIG. 2. At this time, in the circuit of Fig. 4, it is placed before the high frequency emphasis circuit like the circuit of Fig. 1.

Since the integrating circuit 22 is connected, the reproduced waveform is slightly different from that shown in Figure 2, but the high-frequency extortion is performed in exactly the same way as the excursion explained using Figure 2, so the explanation will be given with reference to Figure 2. do.

Waveform C without input delay, 2 seconds delay and reflectance 1
11141 The waveform whose amplitude has been adjusted by the resistor 26 and the added waveform is extracted from the matching grating of the delay line 25 as shown in FIG. The positive phase signal is input to the dynamic amplifier 27. - A signal obtained by delaying the universal signal by 7 seconds is input from the non-matching terminal of the delay line 25 to the negative phase input terminal of the differential amplifier 1127, and the difference between the above waveform C9 and the sum signal is differentially amplified and output. A waveform with a strong high frequency signal II8 and phase distortion removed is outputted to the terminal 28 as shown in FIG. 2f.

According to this application example, the emergency K [R-D by a simple circuit configuration]
It is possible to improve the AT waveform equalization circuit, reduce the cost of 4I&, improve the tonality of the waveform equalization circuit, and simplify #I!.

In this application example, the direct @vc integrator circuit 2 of the reproduction amplifier 2)
2 is connected, and the high frequency emphasis circuits 23 to 28 are connected to the subsequent stage.However, the high frequency enhancement circuits 1111 times 1123 to 28 are connected immediately after the reproduction amplifier 2), and the integrating circuit is connected to the 6I stage. It may also be a circuit configuration in which circuits are connected.

In addition, the configuration of the integrating circuit is not a circuit in which a capacitor is connected in parallel to the feedback resistor of the differential amplifier as shown in Figure 4, but a primary low-pass filter consisting of a capacitor and a resistor is connected to the output of the regenerative amplifier 2), and the subsequent stage is It may also be a circuit to which a buffer amplifier is connected.

Furthermore, instead of separating the integrating circuit 22 and the high frequency emphasizing circuits 23 to 28 as in the circuit shown in FIG. 4, a single differential amplifier may have an integral characteristic and a high frequency emphasizing characteristic. Specifically, in the circuit shown in Fig. 4, the integrating circuit 22 is deleted, the output of the regenerative amplifier 2) is directly connected to the matching resistor 23, and the feedback resistor of the differential amplifier circuit 27 is given integral characteristics. It is sufficient to connect two capacitors in parallel.

Further, in the circuit shown in FIG. 4, the differential amplifier circuit 27 is used as a subtraction means for the signal obtained by the delay line 25, but the delay line 25 It may be added and amplified with the signal obtained from the matching terminal of. Furthermore, in the circuit shown in FIG. 4, the signal obtained from the matching terminal of the delay line 25 is input to the negative phase input terminal of the differential amplifier circuit 27, and the signal obtained from the non-matching terminal is input to the positive phase input terminal. , you can replace this.

Note that in this application example, the integrating circuit 22. and differential amplifier circuit 2
7 is constructed from an operational amplifier, but it can also be constructed from a combination of transistors. Also, the reflectance adjustment resistor 26
And attenuator 24 may be a fixed resistor.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment shows a waveform equalization circuit suitable for application when a magnetic storage device has two read speeds. That is, when the pulse recording interval on the recording medium is constant, it depends on the reading speed 1.

The pulse transmission interval T seconds in FIG. 2 varies. For example, the pulse transmission interval at one readout speed is T seconds,
Assume that the other starting speed is 2T seconds.

At this time, as shown in Fig. 2 a, the pulse with a wide tail relative to the pulse transmission interval rises as shown in Fig. 2 f, and the fall time is equalized to a small pulse, so there is a delay at one readout speed. The delay time of line 2 is set to τ seconds, and the delay time is switched to another reading speed of 2T seconds.

As a result, even if the signal reading speed of the magnetic recording device changes and the pulse transmission interval changes, good pulses can be obtained and data can be detected reliably.

In Figure 6, %29 is a reproduction amplifier, 47 is an integration circuit,
30m and 30b are matching resistors, 31m+31b,
31e, 31d, and 31e are switching transistors that are short-circuited when the signal readout speed of the magnetic recording device is V; 32 is a delay line using an LC low-pass filter;
3 is an attenuator, 34.35 is a reflectance adjustment resistor, 36 is a differential amplifier, 3f is an output terminal of a waveform equalization circuit, and 46 is a control terminal of switching transistors 31&~31e.

The magnetic recording device having the waveform equalization circuit shown in FIG. 5 has two requirements: a relatively slow read speed Wv and a relatively fast read speed V. Here, the recording interval of recording signal pulses on the magnetic tape is constant, the pulse transmission time interval when the read speed is V1 is a relatively long time T1, and the pulse transmission time interval when the read speed is V, is the wing time T. The overall configuration of the circuit shown in FIG. 5 is such that the delay time of one delay line 32 can be varied to .tau. and .tau. in order to correspond to two different pulse transmission time intervals. For this purpose, the transistor switch 31b.

31a and 31d constitute a switching circuit, and the change in characteristic impedance caused by switching the delay time is also changed by transistor switches 31m and 31. The matching resistor and the reflectance adjusting resistor are switched.

Next, the detailed operation of this circuit will be explained.

First, the signal readout speed of the magnetic recording device is relatively fast.
, the reproduction signal obtained by the reproduction amplifier 29 is input to the integrating circuit 47. Next, the output of the integrating circuit is input to the delay line 32 via a matching resistor 30m. here,
Switching transistor 31m, 31b, 31c, 3
1d and 31. are all open, and the resistance value of the matching resistor for the delay time τ8K of the delay line 32 is 3.
It is determined only by 0&. Similarly, the resistance value of the reflectance v4!1 resistor with respect to the delay time τ is determined to be only 34. Furthermore, the delay line 32 is constructed of a seventh-order LC low-pass filter, and each of the built-in capacitors can have its capacity varied between two types.

Now, when a relatively short delay time τ is selected, the switching transistors 31b x 31e and 3
1d is in an open state, the capacity of the code/de/s in the delay line 32 is reduced, and the delay time is shortened.

Three signals obtained from the delay line 32, a signal that does not delay the reproduced signal, a signal that is delayed by seconds, and a signal that is delayed by 2r seconds are input to the differential amplifier 36 as in Figure @4, and output 37 of the waveform equalization circuit. A sharp pulse with small rise and fall times is obtained with respect to the pulse transmission time interval T.

Next, when the readout period of the magnetic recording device is relatively slow Vl, the switching transistors 31a+31b, 3
1a, 31d, and 31. are all short-circuited, and the resistance value of the matching resistor is 3 at the delay time of the delay line 32.
It is determined by the parallel composite value of 0a and 30b. Similarly,
The reflectance g*low resistance resistance value is determined by the parallel composite value of 34 and 35.

Also, the capacitance value of the capacitor in the delay line 32 is such that the switching transistors 31b, 31a, and 31d are in a short-circuit state II.
Since there is IIK, the delay time increases to a relatively long 13 seconds. Therefore, the output terminal 37 of the waveform equalization circuit has a rising edge for the pulse transmission interval T, seconds, and ! A sharp pulse with a short fall time can be obtained.

Generally, delay lines are very expensive and have a large external size, but by employing this embodiment, it is possible to support magnetic recording devices with two different read speeds just by using one delay line. As a result, the cost and space of one circuit can be reduced.

Next, a circuit in which two delay lines are used as a third embodiment of the present invention will be described with reference to FIG. In Figure 6, 3
8 is a reproducing amplifier, and 48 is an integrating circuit.

42m is a delay line with a delay time of 18 seconds, 42b is a delay line with a delay time of τ 1 second, 391 is a matching resistor for delay line 42&, 39b is a matching resistor for delay line 42b, and 42b is a delay line with a delay time of τ1 seconds.
3m is the reflectance adjustment resistor of the 42m delay line.

and 41m is an amplitude adjustment resistor, 43b is a delay line 42b
5 is a reflectance adjustment resistor, and 41b is an amplitude adjustment resistor.
1 is an attenuator, 44 is a differential amplifier, 45 is an inverting circuit, 40
& is a transistor switch that opens only when the delay time τ seconds is selected.

40b is a transistor switch that is opened only when a delay time of 70 seconds is selected, and 49 is a control terminal for transistor switches 40m and 40b.

Next, detailed operation of this circuit will be explained.

First, the signal readout speed of the magnetic recording sickle device is relatively fast (・
When V, the reproduction signal obtained from the reproduction amplifier 38 is input to the integrating circuit 48. Next, since the switching transistor 40m is open and the switching transistor 40b is short-circuited, the output of the integrating circuit 48 is connected to the delay line 42 through the matching resistor 39m.
m is input. At this time, the matching resistor 39b is grounded to the output terminal of the integrating circuit 48;
Since the output resistance of No. 8 is sufficiently smaller than the matching resistances of 39m and 39bK, the amplitude of the reproduced signal does not decrease.

From the reproduced signal input to the delay line 42m, a signal obtained by adding a signal that does not delay the reproduced signal and a signal that delays the reproduced signal by 2τ3 seconds is obtained at the matching terminal of the delay line, and then this signal is applied to the amplitude adjustment resistor 41m. The signal is inputted to the attenuator 51 via the . At this time, since the switching transistor 40b is in a short-circuited state, the amplitude adjustment resistor 41b for the delay line 42b is grounded to the attenuator 510 input terminal. Therefore, the amplitude adjustment resistor 41m and the attenuator 51
b is set in consideration of the state in which the attenuator 51 is connected in parallel.

On the other hand, the signal obtained at the non-matching terminal of the delay line 42m, which delays the reproduced signal by 12 seconds, passes through the reflectance adjustment resistor 43m and is input to the negative phase input terminal of the differential amplifier 44, and then to the positive phase input terminal mentioned above. The difference with the input signal is amplified. At this time, the positive phase amplification section of the differential amplifier 44 has a resistance of 52m and 2 of l52b for taking out the signal from the non-matching terminal of the delay line.
The parallel composite value of two resistors is determined by two feedback resistors. As described above, the pulse transmission time interval T8 is transmitted to the output terminal 50.
It is possible to obtain sharp pulses with short rise and fall times for seconds.

Similar to the above explanation, when the read speed 1 of the magnetic recording device becomes relatively slow vl, the switching transistor 4
0m is short circuit, 40b is open and delay line 42b
The side circuit is selected. Therefore, the output signal of the integrating circuit 48 is connected to the matching resistor 39b.

Delay line 42b, amplitude adjustment resistor 41b, attenuator 51
and a differential amplifier 44 via a reflectance adjustment resistor 43b.
K input and pulse transmission time interval T8 to output terminal 50
It is possible to obtain sharp pulses with short rise and fall times for seconds.

According to this embodiment, the number of switching transistors can be reduced compared to the embodiment described in FIG. Furthermore, since dedicated delay lines are used for the two readout stations, it is easy to optimize each of them.

Note that in the two embodiments shown in FIGS. 5 and 6, the order of the integrating circuit and the high frequency emphasizing circuit may be changed.

Further, the differential amplifier circuit may be configured by combining transistors. Furthermore, all switching transistors may be replaced with mechanical open/close switches.

(Effects of the Invention) According to the IjllK of the present invention, by adjusting the reflectance of the delay line using a single resistor, it is possible to eliminate the phase distortion of the reproduced signal that easily occurs in magnetic storage devices made of rotating heads. Therefore, there is no need to provide a phase distortion removal circuit at Since the adjustment can be significantly simplified compared to the case where the adjustment is performed manually, it is possible to reduce the number of manufacturing steps and improve the reliability of the device.

Furthermore, since it is possible to correspond to the reading stations of two magnetic recording devices with the smallest number of delay lines and differential amplifiers, it is possible to reduce the cost of one circuit and improve the reliability of the circuit.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of the first embodiment l1lf1 of the present invention, and the second
The figure shows the time axis waveform of the main part of the signal in Figure 1, and
The figure is a block diagram of a rotary head type digital audio tape recorder to which the circuit of the first embodiment is applied, FIG. 4 is a circuit diagram showing a specific example of the first embodiment, and FIG. FIG. 6 shows the second embodiment of the present invention. FIG. 7 is a circuit diagram showing a third example. l...Reproduction signal, 2...Delay line, 3...Resistance for matching %4...Reflectance adjustment resistor, 5...Subtraction circuit, 6...Attenuator, 32...Delay line, 31a
~31e. 40m, 40b...Switching transistor for switching delay time

Claims (2)

[Claims] (1) As a waveform equalization means that compensates for the decrease in the amplitude of the signal recorded on the recording medium as the frequency increases,
A delay circuit with a delay time of τ seconds in which only the input terminals are connected with impedance matching, an attenuation circuit that adjusts the amplitude of a signal obtained by adding the input signal of the delay circuit and a signal delayed by 2τ seconds from the input signal, and the delay circuit. A waveform equalization circuit has a circuit that subtracts a signal delayed by τ seconds from the input signal and a signal obtained from the attenuation circuit, and sets the center angular frequency ω_0 for amplitude emphasis to ω_0=π/τ. In the magnetic recording and reproducing apparatus, a means is provided for setting the reflectance at the non-matching terminal of the delay circuit to a value of 1 or less, and the setting means adjusts the phase distortion contained in the reproduced signal in accordance with the signal amplitude compensation. A magnetic recording/reproducing device characterized by performing compensation. (2) When reading a recorded signal from a recording medium, a waveform that has at least two speeds V_1 and V_2 and compensates for the decrease in the amplitude of the signal recorded on the recording medium as the frequency increases As an equalization means, there is a delay circuit with a delay time of τ seconds in which only the input terminal is connected with impedance matching, and an attenuation that adjusts the amplitude of the signal obtained by adding the input signal of the delay circuit and the signal delayed by 2τ seconds from the input signal. a central angular frequency for amplitude enhancement of the waveform equalization circuit in a magnetic recording and reproducing apparatus having a circuit for subtracting a signal obtained from the attenuation circuit and a signal delayed by the input signal by the delay circuit by τ seconds; ω_0 is the read speed V_
1 and ω_0_2 when the reading speed is V_2, the delay time τ is τ_2=π/ω
A delay circuit having a plurality of delay amounts satisfying the relationship such as _0_1 and τ_2=π/ω_0_2 and a switching circuit for selecting one of the plurality of delay amounts are provided, and the central angular frequency at which amplitude enhancement is to be performed is read out. 1. A magnetic recording/reproducing device characterized in that switching is performed between ω_0_1 and ω_0_2 depending on the speed.