JPH06301951A - Driving apparatus for magnetic head - Google Patents

Abstract

PURPOSE:To lighten a movable part to obtain a highly reliable apparatus by eliminating a special detecting member for detecting the speed of a magnetic head. CONSTITUTION:At a time point when only a signal indicating the moving speed of a magnetic head which is generated at a driving coil 7 while a switch SW1 and a switch SW2 are turned off is held by a sample hold circuit 23, a sampling pulse Sc generated at a controlling signal generator 21 is fed to the circuit 23. Only a desired component of the speed signal is extracted at the circuit 23, and the extracted component is amplified by an amplifier 22 and supplied as a speed signal Sd to a subtracter 18 as a subtraction signal. Accordingly, a driving voltage output from the subtracter 18 is in the state restricting well the resonant characteristic of a movable part including the driving coil 7 of a linear direct motor of a voice coil type. Since a detecting member especially for detecting the speed of the magnetic head is eliminated, the movable part is made light and manufactured at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head driving device for displacing a magnetic head by a voice coil type linear DC motor.

[0002]

2. Description of the Related Art In a video tape recorder (VTR) in which an information signal is recorded / reproduced on / from a magnetic tape by using a rotary magnetic head, recording / reproduction for a long time can be performed with a constant amount of magnetic tape. In order to make it possible, if the recording trace width (track width) is narrowed to perform high-density recording / reproducing, the influence of track bending will appear in the reproduced signal output. Therefore, there has been conventionally proposed a VTR in which a rotary magnetic head is attached to a driving device (actuator) and the rotary magnetic head is displaced according to the bending of a track so that a good reproduction signal can be obtained. As the driving device for the above-mentioned rotary magnetic head, for example, a driving device using an electromechanical conversion element constituted by using an electrostrictive substance as disclosed in Japanese Patent Publication No. Sho 58-18686, or, for example, Japanese Patent Laid-Open No. 63- There is a drive device using a voice coil type linear direct current motor (voice coil motor) as disclosed in 173217, etc.

The above-mentioned drive device using the voice coil motor can make displacement larger than that of the drive device using the electromechanical conversion element constituted by using the electrostrictive substance.
Does not require high voltage for driving. It is often used as a drive device of a magnetic head because it has advantages such as easy control. A driving device using a voice coil motor is disclosed in, for example, the above-mentioned Japanese Patent Laid-Open No. 63-17321.
As disclosed in Japanese Patent Publication No. 7, a coil bobbin around which a coil is wound is arranged so that it can be displaced in the coil axial direction in a magnetic gap formed between a magnetic path member and a pole piece. Is supported by non-magnetic plate springs near both ends of the magnetic head, and a magnetic head is attached to one end of one of the plate springs. The head is driven and displaced in the direction of the coil axis.

Since the above-mentioned non-magnetic plate spring is formed into a shape having a low mechanical impedance so that it can be easily displaced in the coil axial direction, the mechanical part of the movable part is mechanically reduced. Since the resonance frequency becomes low, the control band cannot be widened, or the mechanical resonance of the movable part causes a large amplitude displacement, which makes it difficult to position the magnetic head with high accuracy. It can happen. As a means for suppressing the large-amplitude displacement due to the mechanical resonance of the movable part, for example, there is a method in which a viscous fluid is put between the fixed part and the movable part to dampen mechanical vibrations. However, there are problems such as that the damping characteristics of the viscous fluid used change due to changes in temperature, changes over time, and it is difficult to seal the viscous fluid between the fixed part and the movable part. there were.

Therefore, also in the magnetic head drive device using the voice coil motor, the speed information of the movable portion is detected and negatively fed back to the drive system of the movable portion to electrically dump the movable portion. It has been attempted to apply a so-called motional feedback means, in which an amplitude is added to suppress the amplitude of the movable portion at the time of resonance. FIG. 12 is a vertical cross-sectional side view showing a configuration example of a drive mechanism portion in a magnetic head drive device using a voice coil motor, which has been conventionally used when the above-described motional feedback means is applied. In the drive mechanism portion of the magnetic head drive device shown in FIG. 12, a permanent magnet 3 having a central hole and a pole piece 4 having a central hole are provided in a hollow portion of a hollow yoke 1 having a central hole 2 at the bottom. It is assembled so that the central holes of the above-mentioned respective constituent parts communicate with each other.

The coil bobbin 6 is driven and displaced in a magnetic gap 5 formed between the outer peripheral surfaces of both the permanent magnet 3 and the pole piece 4 and the inner peripheral surface of the hollow portion of the yoke 1 described above. As described above, the support shaft 8 to which one end of the coil bobbin 6 is fixed is pierced in the center hole of each of the above-mentioned components in a loosely fitted state, and is provided outside the above-mentioned yoke 1 in the support shaft 8. The protruding end portion 8a and the one end portion 6a of the coil bobbin 6 are respectively provided as separate support members 1
It is supported by 0 and 11. A holder 9 of the magnetic head is fixed to the end 8a of the support shaft projecting from the center hole 2 provided in the bottom of the yoke 1 to the outside of the yoke 1. The magnetic head H is fixed to the tip. Further, the coil bobbin 6 is provided with a drive coil 7 and a speed detection coil 12, and by supplying drive power to the drive coil 7, the magnetic head H moves in the central axis direction of the drive coil 7. Is driven and displaced, a signal having velocity information of the magnetic head H is generated in the velocity detection coil 12 described above.

[0007]

By the way, as shown in FIG. 12, a magnetic head driving device using a voice coil motor of a conventional structure in which a coil bobbin 6 is provided with a driving coil 7 and a speed detecting coil 12. In the drive mechanism portion of, the speed detection coil 12 detects the speed information of the movable portion including the magnetic head H, the speed information is negatively fed back to the drive system of the movable portion, and the movable portion is electrically damped. Therefore, when the amplitude of the movable portion at the time of resonance is suppressed, a large signal level crosstalk occurs from the drive coil 7 to the speed detection coil 12, and moreover, the drive coil 7 causes the speed detection coil to cross. The crosstalk component having a large signal level given to 12 is a differential value of the drive signal supplied to the drive coil 7, and is detected by the speed detection coil 12. The speed detection signal is very large compared to the speed detection signal, and it is difficult to separate it from the speed detection signal with high accuracy, and the speed detection coil 12 is added to the movable part. Since the weight of the movable part becomes heavier, the mechanical resonance frequency of the movable part is lowered, so that the control band cannot be widened. Furthermore, the voice coil motor mounted on the rotary drum side. In order to transmit the speed detection signal generated in the speed detecting coil 12 in the magnetic head driving device to the control device provided in the fixed part of the device, an expensive slip ring and brush, a rotary transformer, or the like is used. The use of components is required, which causes problems such as increased cost and reduced reliability.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a magnetic head driving device for displacing a magnetic head by a voice coil type linear DC motor to which driving power is supplied. Means for intermittently performing the above, a means for detecting the moving speed signal of the magnetic head from the coil of the voice coil type linear DC motor during the period when the drive power is not supplied, and a means for detecting the detected magnetic head. A magnetic head driving device provided with means for negatively feeding back a moving speed signal to a coil driving power supply circuit of a voice coil type linear DC motor, and a magnetic head driving device described above, wherein a voice coil type linear DC During the period when the drive power supply to the motor coil is stopped, the voice coil type linear DC The drive of the magnetic head comprising means for connecting the coil of the voice coil type linear DC motor to the reference potential point before the moving speed signal of the magnetic head is detected from the coil of the motor. In the device and the drive device for the magnetic head described above,
The moving speed signal of the magnetic head in the signal including the moving speed signal of the magnetic head detected from the coil of the voice coil type linear DC motor during the period when the supply of the driving power to the coil of the voice coil type linear DC motor is stopped. In a magnetic head drive device having a circuit arrangement for canceling out signal components other than the above, and in the magnetic head drive device described above, immediately before the supply of drive power to the coil of the voice coil type linear DC motor is stopped, A voltage having a magnitude and a polarity opposite to that of the drive voltage originally to be supplied to the coil is applied to the coil of the voice coil type linear DC motor immediately before the supply of the drive power to the coil is stopped. There is provided a magnetic head driving device including a means.

[0009]

The magnetic head is induced in the coil of the voice coil type linear DC motor by intermittently supplying the drive electric power to the coil of the voice coil type linear DC motor, and during the period when the driving power is not supplied. The moving speed signal is detected and is negatively fed back to the drive power supply circuit for the coil of the voice coil type linear DC motor. Also,
During the period in which the supply of the drive power to the coil of the voice coil type linear DC motor is stopped, before the moving speed signal of the magnetic head is detected from the coil of the voice coil type linear DC motor, the above-mentioned voice coil type linear DC motor is detected. After connecting the coil of the DC motor to the reference potential point, detect the moving speed signal of the magnetic head from the coil, or while the supply of drive power to the coil of the voice coil type linear DC motor is stopped. , A signal component other than the moving speed signal of the magnetic head in the signal including the moving speed signal of the magnetic head detected from the coil of the voice coil type linear DC motor can be canceled, or the coil of the voice coil type linear DC motor can be driven. Immediately before the power supply is stopped, the relationship between the drive voltage value originally to be supplied to the coil and the By applying a voltage of opposite magnitude and of opposite polarity to the coil just before the supply of drive power to the coil of the voice coil type linear DC motor is stopped, the moving speed of the magnetic head from the coil can be increased. Make sure the signal is well detected.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The specific contents of the magnetic head driving device of the present invention will be described in detail below with reference to the accompanying drawings.
1, FIG. 3, FIG. 5, FIG. 7, and FIG. 9 are block diagrams showing an embodiment of the magnetic head driving device of the present invention, and FIG. 2, FIG. 4, FIG. 6, FIG. FIG. 11 is a waveform example diagram for explaining the operation of the magnetic head driving device of the present invention shown in FIGS. 3, 5, 7 and 9, and FIG. 11 is used in the magnetic head driving device of the present invention. FIG. 12 is a sectional view of a drive mechanism portion, and FIG. 12 is a sectional view of a drive mechanism portion used in a conventional magnetic head drive device. The magnetic head drive device of the present invention comprises means for intermittently supplying drive power to the coil of a voice coil type linear DC motor, and a voice coil type linear motor during a period in which drive power is not supplied. A means for detecting the moving speed signal of the magnetic head from the coil of the DC motor and a means for negatively feeding back the detected moving speed signal of the magnetic head to the drive power supply circuit for the coil of the voice coil type linear DC motor are provided. The drive mechanism portion HDA used in the magnetic head drive device of the present invention is the drive mechanism portion in the conventional magnetic head drive device described above with reference to FIG. A structure having a structure in which the speed detecting coil 12 provided in the above is removed, for example, a structure as shown in FIG. 11 is used.

The drive mechanism portion HDA in the magnetic head drive device shown in FIG. 11 has a permanent magnet 3 having a central hole and a pole piece having a central hole in the hollow portion of a hollow yoke 1 having a central hole 2 at the bottom. 4 are assembled so that the center holes of the respective constituent parts communicate with each other, and the outer peripheral surfaces of both the permanent magnet 3 and the pole piece 4 and the inner peripheral surface of the hollow portion of the yoke 1 described above. The support shaft 8 to which one end of the coil bobbin 6 is fixed so that the coil bobbin 6 is driven and displaced in the magnetic gap portion 5 formed between An end portion 8a of the support shaft 8 that penetrates through the yoke 1 and protrudes to the outside of the yoke 1 and one end portion 6a of the coil bobbin 6 are supported by individual support members 10 and 11, respectively. Then, the end portion 8 of the support shaft projecting to the outside of the yoke 1 from the center hole 2 provided in the bottom portion of the yoke 1 described above.
The magnetic head holder 9 is fixed to a, and the magnetic head H is fixed to the tip of the magnetic head holder 9. In addition, the coil bobbin 6 has a driving coil 7
Is provided, and by supplying driving power to the drive coil 7, the magnetic head H is driven and displaced in the central axis direction of the drive coil 7.

In each of the block diagrams of FIGS. 1, 3, 5, 7 and 9 showing the different embodiments of the magnetic head driving apparatus of the present invention, the portion shown as block HDA is A drive mechanism portion HDA in a magnetic head drive device for displacing a magnetic head by a voice coil type linear DC motor to which drive power is supplied. The drive mechanism portion HDA is as exemplified in FIG. 11 described above. Configurations may be used. Reference numeral 7 in the drawing is a drive coil in the voice coil type linear DC motor. Since the drive mechanism portion HDA in the magnetic head driving device for displacing the magnetic head by the above-mentioned voice coil type linear DC motor is provided on the rotating drum as described above, the voice coil type linear DC from the fixed side of the device. The drive power is supplied to the drive coil 7 of the motor by the slip rings 13 and 14 and the brush 1.
5 and 16 are used.

In each of the drawings showing the magnetic head driving apparatus of the present invention, reference numeral 17 denotes a driving voltage supply terminal, and
18 is a subtractor, 19 is a drive circuit, SW1 is a switch, 2
Reference numeral 0 is a clock pulse generator, 21 is a control signal generator (timing pulse generation circuit), 22 is an amplifier, 23 is a sample hold circuit, and SW2 in FIGS. 3 and 9 is a switch for short-circuiting the drive coil 7. , And further in FIG.
Further, 24 in FIG. 9 is a level adjusting circuit, 25 is an adder, 26 in FIGS. 7 and 9 is a sample hold circuit, 27 is an inverter, 28 is a level adjusting circuit, and SW3 is a switch.

In the magnetic head drive apparatus of the present invention shown in FIG. 1, the drive voltage supplied to the drive voltage supply terminal 17 is supplied to the subtractor 18 as the augend signal, and the subtractor 18 is supplied with an amplifier. Speed signal Sd output from 22
{(D) of FIG. 2) is supplied as the subtraction signal, and the subtracter 18 outputs the difference signal between the driving voltage and the speed signal, which is supplied to the drive circuit 19. The output signal from the drive circuit 19 is the brush 16 → the slip ring 14 → the drive coil 7 of the voice coil type linear DC motor of the drive mechanism part HDA in the drive device of the magnetic head → the slip while the switch SW1 is in the ON state. The magnetic head H is driven to be displaced in the central axis direction of the drive coil 7 by flowing in the circuit of the ring 13 → brush 15 → ground. The switch SW1 is turned on during the high level period of the switching signal Sa {(a) in FIG. 2} generated by the control signal generating circuit 21, and the low level of the switching signal Sa is maintained. Since the switch SW1 is turned off during the state period, the switch SW1 is intermittently turned on by the switching signal Sa.

The drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive device of the magnetic head has both the permanent magnet 3 and the pole piece 4 as shown in FIG. The drive coil 7 is movably supported in the magnetic space 5 formed between the outer peripheral surface and the inner peripheral surface of the hollow portion of the yoke 1. Therefore, when drive power is supplied to the drive coil 7, the drive coil is driven. The drive coil 7 moves due to the electromagnetic force generated between the magnetic field 7 and the magnetic field. When the drive coil 7 moves in the magnetic field as described above, a voltage corresponding to the moving speed is generated in the drive coil 7,
If the voltage generated corresponding to the moving speed in the drive coil 7 is measured, the moving speed of the drive coil 7, that is,
The moving speed of the magnetic head can be measured.

Then, the switch SW1 is turned on / off by the switching signal Sa, and the switch SW1
It suffices to measure the voltage generated in the drive coil 7 in correspondence with the moving speed during the period when the switch is off. When the switch SW1 repeats the on / off operation, the drive in the magnetic head drive device is performed. Terminal voltage S generated in the drive coil 7 of the voice coil type linear DC motor of the mechanical part HDA
The waveform of b is the voltage Sb at the terminal of the drive coil 7 when the state is as illustrated in FIG. 2B, that is, when the state of energization is cut off from the state of energization.
Is a voltage having the opposite polarity to the voltage up to that point, which is transiently generated from the time when the current is cut off, based on the magnetic energy stored in the coil at the time of the previous power supply.
If the switch SW1 is turned on / off by the switching signal Sa and the voltage generated in the drive coil 7 is measured while the switch SW1 is off, the moving speed of the drive coil 7, that is, However, the moving speed of the magnetic head cannot always be measured.

Therefore, in the embodiment shown in FIG. 1, the drive coil 7 is operated while the switch SW1 is off.
Moving speed of the drive coil 7 generated in
The sampling pulse Sc generated by the control signal generator 21 at the time when only the signal indicating the moving speed of the magnetic head is sample-held by the sample-hold circuit 23.
{(C) of FIG. 2 is the sample hold circuit 2 described above.
Therefore, only the desired velocity signal component can be extracted. The speed signal component extracted by the sample hold circuit 23 is amplified by the amplifier 22 and supplied to the subtractor 18 as a subtraction signal as the speed signal Sd as illustrated in FIG. As a result, the drive voltage output from the subtractor 18 is in a state in which the resonance characteristic of the movable portion including the drive coil 7 of the voice coil type linear DC motor can be suppressed well.

Next, the magnetic head driving apparatus of the present invention shown in FIG. 3 has a configuration mode in which a switch SW2 is added to the magnetic head driving apparatus of the present invention illustrated in FIG. When the switch SW2 is turned on by the opening / closing control signal supplied from the control signal generator 21, the slip rings 13, 14 are connected to the drive coil 7 of the voice coil type linear DC motor. A short circuit is established between the brushes 15 and 16 connected via the brushes. That is, the open / close control signal Se used to control the open / closed state of the switch SW2 is at a low level when the switch SW1 is turned off, as shown in FIG. From the state of to the high level state, switch SW2 is turned on, and
The sample hold signal Sc shown in (c) of FIG.
At a time position immediately before being supplied to the sample hold circuit 23, the switch SW2 is turned off from the high level state to the low level state, so that the switch SW1 is shown in FIG. When the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive device of the magnetic head is turned off by the switching signal Sa being turned on and the energization is cut off from the energized state, the drive described above is performed. The coil 7 is short-circuited by the switch SW2.

Therefore, when the switch SW1 is turned off, the magnetic energy accumulated in the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive device of the magnetic head during the previous energization. On the basis of the above, the unnecessary voltage having the opposite polarity to the voltage generated transiently does not appear due to the short-circuiting operation of the drive coil 7 by the switch SW2. This point is apparent from FIG. 4B showing the terminal voltage Sb of the drive coil 7 in the embodiment of the magnetic head drive apparatus shown in FIG. That is, FIG. 1 does not include the switch SW2 for short-circuiting the drive coil 7 at the start of the interruption period of the energization operation for the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive device for the magnetic head. In the embodiment of the magnetic head drive device shown, the above-mentioned unnecessary voltage transiently generated in the drive coil 7 is detected from the drive coil 7 when the switch SW1 is turned off. The time position for sampling the speed signal of the magnetic head generated in the drive coil 7 is largely separated from the time when the switch SW1 is turned off so as not to adversely affect the detection value of the speed signal of the magnetic head. The necessity is easily understood from FIG. 2 (b).

However, at the start of the interruption period of the energization operation to the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive device of the magnetic head,
In the embodiment of the magnetic head drive device shown in FIG. 3, which comprises a switch SW2 for short-circuiting the drive coil 7, the drive coil 7 is transiently switched when the switch SW1 is turned off. Since the above-mentioned unnecessary voltage that occurs in the drive coil 7 is removed in a short time by the short-circuiting operation of the drive coil 7 by the switch SW2, the time position for sampling the velocity signal of the magnetic head generated in the drive coil 7 is
The switch SW1 does not have to be far apart from the time when it is turned off, and therefore the ratio of the off-state period to the on-state period of the switch SW1 is set to the value of the embodiment of the magnetic head driving device shown in FIG. It can be made smaller than in the case, the driving efficiency of the voice coil type linear DC motor can be increased, and the maximum torque can be increased.

In the embodiment shown in FIG. 3, the drive coil 7 is generated in the drive coil 7 while the switch SW1 is off and the switch SW2 is off.
Of the magnetic head, that is, the sampling pulse Sc generated by the control signal generator 21 at the time when only the signal indicating the moving speed of the magnetic head is sample-held by the sample-hold circuit 23 ((c) of FIG. 4). } Is applied to the sample and hold circuit 23 described above, so that only the desired speed signal component is extracted, and the speed signal component extracted by the sample and hold circuit 23 described above is output to the amplifier 2
2 is supplied as a subtraction signal to the subtracter 18 as a speed signal Sd as illustrated in FIG. 4D, whereby the driving voltage output from the subtractor 18 is The resonance characteristics of the movable portion including the drive coil 7 of the voice coil type linear DC motor can be suppressed well.

Next, the magnetic head driving apparatus of the present invention shown in FIG. 5 has a sample hold circuit 23 in the magnetic head driving apparatus of the present invention illustrated in FIG.
By adjusting the signal level of the speed signal by adding a part of the drive signal to the output signal of the above, when the switch SW1 is turned off, the drive mechanism part HDA of the drive unit of the magnetic head in the drive device of the magnetic head is previously energized. On the basis of the magnetic energy accumulated in the drive coil 7 of the voice coil type linear DC motor, the drive coil 7 is affected by an unnecessary voltage having a reverse polarity with respect to the transiently generated voltage. This is an example of a case where the speed signal of the magnetic head is set so as not to extend for a long time.

That is, in the magnetic head drive device of the present invention shown in FIG. 5, the velocity signal component of the magnetic head generated in the drive coil 7 of the voice coil type linear DC motor during the period in which the switch SW1 is off. The output signal of the sample-and-hold circuit 23 that is sampling is given to the adder 25, and the output signal of the sample-and-hold circuit 23 in the adder 25 and the drive voltage supplied to the drive voltage supply terminal 17 are The voltage is adjusted by the level adjusting circuit 24 to obtain a speed signal, and the speed signal is amplified by the amplifier 20 and given to the subtractor 18 as a subtraction signal.

As described above, when the switch SW1 is turned off, it is stored in the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive unit of the magnetic head when the current is applied. Based on the magnetic energy, the magnitude of the unnecessary voltage having the opposite polarity to the voltage generated transiently is supplied to the drive coil 7 before the switch SW1 is turned off. Since it may be considered that the relationship is proportional to the magnitude of the driving voltage, the sample that is the sampling value in a state where the speed signal component of the magnetic head generated in the driving coil 7 includes an unnecessary voltage component. The adder 25 adds the output signal of the hold circuit 23 and the signal of which the level of the drive voltage has been adjusted by the level adjusting circuit 24, by the adder 25. The output signal, it is possible to obtain a velocity signal component of the magnetic head in a state where unnecessary voltage component mentioned above is not remained for a long time.

Therefore, when the switch SW1 is turned off, the magnetic energy accumulated in the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive device of the magnetic head during the previous energization. On the basis of the above, the unnecessary voltage having the opposite polarity to the voltage that has been generated transiently indicates the terminal voltage Sb of the drive coil 7 in the embodiment of the magnetic head drive device shown in FIG. As shown in FIG. 6 (b),
Since it will be canceled in a short time on the time axis,
In the embodiment of the magnetic head drive device shown in FIG. 1, the unnecessary voltage transiently generated in the drive coil 7 is removed in a short time when the switch SW1 is turned off. , The time position for sampling the speed signal of the magnetic head generated in the drive coil 7 is set to the switch S.
It is not necessary to largely separate from the time when W1 is turned off. Therefore, the ratio of the off-state period to the on-state period of the switch SW1 is set in the case of the embodiment of the magnetic head driving device shown in FIG. It is possible to increase the driving efficiency of the voice coil type linear DC motor and increase the maximum torque.

In the embodiment shown in FIG. 5, only the signal indicating the moving speed of the driving coil 7 generated in the driving coil 7 during the period when the switch SW1 is off, that is, the moving speed of the magnetic head is sampled. The sampling pulse Sc {(c) in FIG. 6} generated by the control signal generator 21 is applied to the sample hold circuit 23 at the time when the sample is held by the hold circuit 23. Of the speed signal component is extracted, and the speed signal component extracted by the sample hold circuit 23 is amplified by the amplifier 22 to obtain the subtractor 18 as the speed signal Sd as illustrated in FIG. Is supplied to the voice coil type linear DC motor as a subtraction signal. The resonance characteristic of the movable portion including the moving coil 7 can be suppressed well.

Next, the magnetic head driving device of the present invention shown in FIG. 7 outputs the output signal of the subtracter 18 in the magnetic head driving device of the present invention shown in FIG.
A state in which the drive circuit 19 is supplied via the switch SW3 and a signal whose level is adjusted by inverting the polarity of the output signal of the subtractor 18 is supplied to the drive circuit 19 via the switch SW3. Are switched in a time-division manner during the ON state of the switch SW1, so that the magnetic head shown in FIG. 7 is displayed even when the switch SW1 is changed from the ON state to the OFF state. As shown in FIG. 8B, which shows the state of the change of the terminal voltage Sb of the drive coil 7 on the time axis in the example of the driving device of FIG. A configuration example is shown in which the drive coil 7 of the HDA voice coil type linear DC motor is configured so that an unnecessary voltage does not appear.

That is, in the magnetic head driving apparatus of the present invention shown in FIG. 7, the output signal from the subtractor 18 is supplied to the fixed contact a of the switch SW3 and the sample hold circuit 26. The sample-and-hold circuit 26 described above samples the signal output from the subtractor 18 and holds it at the time of the sample-and-hold signal Sf generated by the control signal generator 21 (see (f) in FIG. 8). To do. The output signal from the sample hold circuit 26 is supplied to the level adjusting circuit 28 after the polarity is inverted by the inverter 27 and the signal level is adjusted, and then applied to the fixed contact b of the switch SW3. The movable contact v of the switch SW3 described above is
The switching control signal Sg generated by the control signal generator 21 (see (g) of FIG. 8) is switched to the fixed contact a side while the switching control signal Sg (see (g) of FIG. 8) is at the high level, and the switching control signal S described above is used.
During the period when g is at the low level, it is switched to the fixed contact b side.

The switching control signal S of the switch SW3 described above.
At the time when g changes from the high level state to the low level state, the sample hold signal Sf given from the control signal generator 21 to the sample hold circuit 26 described above (see (f) in FIG. 8). Just after
Further, the switching control signal Sg of the switch SW3 described above is
At the time when the low level state changes to the high level state, the switching signal Sa (see (a) of FIG. 8) supplied from the control signal generator 21 to the switch SW1 changes from the high level state to the low level state. It is a time of change. During the period when the switch SW1 is turned on, the movable contact v of the switch SW3 is fixed to the fixed contact a.
Since the difference signal between the driving voltage output from the subtractor 18 and the speed signal Sd is applied to the fixed contact a side of the switch SW3 during the period when the signal is switched to the side, the signal is, for example, the switch. Fixed contact a of SW3 → movable contact v →
Drive circuit 19 → switch SW1 → brush 16 → slip ring 14 → drive mechanism part of magnetic head drive device Drive coil 7 of voice coil type linear DC motor of HDA → slip ring 13 → brush 15 → ground circuit (or ground, for example) → brush 15 → slip ring 1
3-> Drive mechanism part HDA in the drive device of the magnetic head
Voice coil type linear DC motor drive coil 7 → slip ring 14 → brush 16 → switch SW 1 → drive circuit 19 → switch SW 3 movable contact v → fixed contact a →
Circuit) to drive and displace the magnetic head H in the central axis direction of the drive coil 7.

Then, immediately before the time when the movable contact v of the switch SW3 is switched from the fixed contact a side to the fixed contact b side, the sample hold signal Sf {supplied from the control signal generator 21 to the sample hold circuit 26. 8 (f)}, the difference signal between the driving voltage and the speed signal Sd output from the subtractor 18 at that time is sampled and held by the sample hold circuit 26,
In the state where the signal held in the sample hold circuit 26 has its polarity inverted by the inverter 27 and then the signal level is adjusted by the level adjusting circuit 28 and supplied to the fixed contact b of the switch SW3, the control signal generator 2
The switching control signal Sg supplied from 1 to the switch SW3
According to {see (g) of FIG. 8}, the switch SW
When the movable contact v of 3 is switched from the fixed contact a side to the fixed contact b side, the signal whose signal level is adjusted by the level adjustment circuit 28 as described above is, for example, ground → brush 15 → slip ring 13 → Circuit of the drive coil 7 of the voice coil type linear DC motor of the drive mechanism part HDA in the drive device of the magnetic head → slip ring 14 → brush 16 → switch SW1 → drive circuit 19 → movable contact v of switch SW3 → fixed contact b → Alternatively, for example, fixed contact b of switch SW3 → movable contact v → drive circuit 19 →
Switch SW1 → brush 16 → slip ring 14 → driving mechanism part in magnetic head driving device HDA voice coil type linear DC motor drive coil 7 → slip ring 13 → brush 15 → ground circuit) When the movable contact v of SW3 is switched to the fixed contact a side, current is stored in the drive coil 7 by the current flowing in the drive coil 7 of the voice coil type linear DC motor of the drive mechanism part HDA in the magnetic head drive device. The stored magnetic energy is removed.

In this state, even if the switch SW1 is changed from the ON state to the OFF state, it is accumulated in the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the magnetic head drive device during the previous energization. Since there is no magnetic energy that was used, switch SW as described above
Even if 1 is switched from the on state to the off state, no unnecessary voltage is generated in the drive coil 7, which is shown in FIG.
8B showing the terminal voltage Sb of the drive coil 7 in the embodiment of the magnetic head drive device shown in FIG.
You can understand clearly by looking at. In the above example, the length of the low level period of the switching control signal Sg of the switch SW3 is kept constant and the magnitude of the signal supplied to the fixed terminal b of the switch SW3 is changed. Contrary to the case of the above example, the magnitude of the signal supplied to the fixed terminal b of the switch SW3 is kept constant, and the time length of the low level period of the switching control signal Sg of the switch SW3 is made variable, The magnetic energy stored in the drive coil 7 of the voice coil type linear DC motor of the drive mechanism portion HDA in the drive unit for the magnetic head may be canceled when the power is applied. Also,
An example of the terminal voltage Sb of the drive coil 7 is shown in (h) of FIG. 8 so that the amount of charge held in the sample hold circuit 26 is gradually decreased to the reference potential on the time axis. If the signal Sb is used to show a change on the time axis, there is an advantage that overcorrection due to an adjustment error can be prevented.

Next, the magnetic head driving apparatus of the present invention shown in FIG. 9 is the same as the magnetic head driving apparatus of the present invention described above with reference to FIGS. 1, 3, 5, and 7. 10 shows an embodiment configured so as to have all of the adopted configuration modes, and various signals Sa to Sg shown in FIG. 9 are shown in (a) to (g) of FIG. )
Is shown in. The configuration and operation of the magnetic head driving device of the present invention shown in FIG. 9 are described for each embodiment of the magnetic head driving device of the present invention described above with reference to FIGS. Since it can be easily understood by referring to (a) to (g) of FIG. 10, detailed description thereof will be omitted.

[0033]

As is apparent from the above detailed description, the magnetic head driving device of the present invention intermittently supplies the driving power to the coil of the voice coil type linear DC motor to reduce the driving power. While the power is not being supplied, the moving speed signal of the magnetic head induced in the coil of the voice coil type linear DC motor is detected, and the detected signal is supplied to the coil drive power supply circuit of the voice coil type linear DC motor. Before the magnetic head moving speed signal is detected from the coil of the voice coil type linear DC motor during the period of feeding back and the supply of the driving power to the coil of the voice coil type linear DC motor is stopped, After connecting the coil of the voice coil type linear DC motor to the reference potential point, the moving speed of the magnetic head is transmitted from the coil. Of the magnetic head that is detected from the coil of the voice coil type linear DC motor during the period when the drive power supply to the coil of the voice coil type linear DC motor is stopped. A signal component other than the moving speed signal of the head is canceled, and the drive voltage value originally to be supplied to the coil immediately before the supply of the drive power to the coil of the voice coil type linear DC motor is stopped. A magnetic head driving apparatus according to the present invention, wherein a voltage having a magnitude and a reverse polarity is applied to the coil of a voice coil type linear DC motor immediately before the supply of driving power to the coil is stopped. However, since a dedicated detection member for detecting the speed of the magnetic head is not provided, the moving part can be made lighter and the speed detection signal It can be manufactured at low cost without causing crosstalk of motion signals, and has high reliability because it does not require a dedicated slip ring or brush for transmitting speed signals. The advantage is that the device can be provided at a low price.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic head driving device of the present invention.

FIG. 2 is a waveform example diagram for explaining the operation of the magnetic head driving device of the present invention shown in FIG.

FIG. 3 is a block diagram showing an embodiment of a magnetic head driving device of the present invention.

FIG. 4 is a waveform example diagram for explaining the operation of the magnetic head driving device of the present invention shown in FIG.

FIG. 5 is a block diagram showing an embodiment of a magnetic head driving device of the present invention.

FIG. 6 is a waveform example diagram for explaining the operation of the magnetic head driving device of the present invention shown in FIG.

FIG. 7 is a block diagram showing an embodiment of a magnetic head driving device of the present invention.

FIG. 8 is a waveform example diagram for explaining the operation of the magnetic head driving device of the present invention shown in FIG. 7.

FIG. 9 is a block diagram showing an embodiment of a magnetic head driving device of the present invention.

10 is a waveform example diagram for explaining the operation of the magnetic head driving device of the present invention shown in FIG.

FIG. 11 is a sectional view of a drive mechanism portion used in the magnetic head drive device of the present invention.

FIG. 12 is a cross-sectional view of a drive mechanism portion used in a conventional magnetic head drive device.

[Explanation of symbols]

1 ... Hollow yoke, 2 ... Center hole, 3 ... Permanent magnet, 4 ...
Pole piece, 5 ... Magnetic air gap, 6 ... Coil bobbin, 7
... Drive coil, 8 ... Support shaft, 9 ... Magnetic head holder,
10, 11 ... Support member, 12 ... Coil for speed detection, 1
3, 14 ... Slip ring, 15, 16 ... Brush, 17
... Drive voltage supply terminal, 18 ... Subtractor, 19 ... Drive circuit, 20 ... Clock pulse generator, 21 ... Control signal generator (timing pulse generation circuit), 22 ... Amplifier, 23
... sample hold circuit, 24, 28 ... level adjustment circuit, 25 ... adder, 26 ... sample hold circuit, 27
... Inverter, SW1 to SW3 ... Switch, H ... Magnetic head, HDA ... Drive mechanism part in magnetic head drive device,

Claims (4)

[Claims] 1. A drive device for a magnetic head, wherein a magnetic head is displaced by a voice coil type linear direct current motor to which drive electric power is supplied, so that the drive electric power is intermittently supplied to the coil of the voice coil type linear direct current motor. Means for detecting the moving speed signal of the magnetic head from the coil of the voice coil type linear DC motor during the period when the drive power is not supplied, and the detected moving speed signal of the magnetic head. Drive device for a magnetic head, which is provided with means for providing negative feedback to a drive power supply circuit for a coil of a linear DC motor. 2. In a magnetic head drive device for displacing a magnetic head by a voice coil type linear DC motor to which drive power is supplied, the drive power is intermittently supplied to the coil of the voice coil type linear DC motor. Means for detecting the moving speed signal of the magnetic head from the coil of the voice coil type linear DC motor during the period when the drive power is not supplied, and the detected moving speed signal of the magnetic head. In a drive device for a magnetic head, which is provided with means for providing negative feedback to a drive power supply circuit for a coil of a linear DC motor,
During the period in which the supply of the drive power to the coil of the voice coil type linear DC motor is stopped, before the moving speed signal of the magnetic head is detected from the coil of the voice coil type linear DC motor, the above-mentioned voice coil type linear DC motor is detected. A drive device for a magnetic head, comprising means for allowing a coil of a DC motor to be connected to a reference potential point only once. 3. A drive device for a magnetic head, wherein a magnetic head is displaced by a voice coil type linear DC motor to which drive power is supplied, so that drive power is intermittently supplied to a coil of the voice coil type linear DC motor. Means for detecting the moving speed signal of the magnetic head from the coil of the voice coil type linear DC motor during the period when the drive power is not supplied, and the detected moving speed signal of the magnetic head. In a drive device for a magnetic head, which is provided with means for providing negative feedback to a drive power supply circuit for a coil of a linear DC motor,
The moving speed signal of the magnetic head in the signal including the moving speed signal of the magnetic head detected from the coil of the voice coil type linear DC motor during the period when the supply of the driving power to the coil of the voice coil type linear DC motor is stopped. A magnetic head driving device comprising a circuit arrangement for canceling out signal components other than the above. 4. A drive device for a magnetic head in which a magnetic head is displaced by a voice coil type linear DC motor to which drive power is supplied, so that the drive power is intermittently supplied to the coil of the voice coil type linear DC motor. Means for detecting the moving speed signal of the magnetic head from the coil of the voice coil type linear DC motor during the period when the drive power is not supplied, and the detected moving speed signal of the magnetic head. In a drive device for a magnetic head, which is provided with means for providing negative feedback to a drive power supply circuit for a coil of a linear DC motor,
Immediately before the supply of the driving power to the coil of the voice coil type linear DC motor is stopped, a voltage of reverse polarity having a magnitude related to the driving voltage value that should be originally supplied to the coil is applied to the coil of the voice coil type linear DC motor. A magnetic head drive device comprising means for applying the drive power to the coil immediately before the supply of drive power to the coil is stopped.