JP3124110B2 - Drive device for voice coil motor and tape drive device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice coil motor driving device and a tape driving device using the same, and more particularly, to a tape driving device provided in a VTR device or the like to control the height of a tape fed from a cassette with high precision. The present invention relates to a device suitable for use in a tape drive device.

SUMMARY OF THE INVENTION The present invention relates to a voice coil motor driving device used for performing high-precision positioning using a voice coil motor and a tape driving device using the same, and particularly to a cassette type driving device. When supplying and winding the tape of the video tape recorder, the voice coil motor provided on the reel mechanism is driven in accordance with the vertical movement of the tape at the cassette entrance and exit, thereby displacing the reel and controlling the vertical movement of the tape. When canceling, the voice coil motor is applied with an AC bias current having a predetermined frequency and level that does not affect the tape running, thereby improving the non-linear operation of the voice coil motor. Reduces fluctuations faithfully even for small fluctuations of tape, Stabilize the line.

[0003]

2. Description of the Related Art As a tape drive device provided in a VTR device or the like and for controlling the height of a tape fed from a cassette with high accuracy, a tape guide post as disclosed in Japanese Patent Application Laid-Open No. 3-209658 has been conventionally used. There is known a device for controlling the height of a tape by providing a voice coil motor inside the device.

In addition to such devices, there is also known a tape drive device that controls the height of a tape by providing a voice coil motor in a reel device, for example.

FIG. 5 is a configuration diagram showing an example of a tape running system used in such a tape drive.

In the tape running system of the tape drive shown in FIG. 1, when recording or reproducing a signal on or from a tape 152 in a cassette 151, each of the posts 153 to 161 is used.
The tape 152 is pulled out from the cassette 151 by using the head 152, the full-width head 162, the impedance roller 163, the rotating head 164, and the audio head 16.
9, and the tape 152 is pressed against the capstan shaft 166 by a pinch roller 165,
Further, while rotating the tape 152 by rotating each of the reel devices 167 and 168 and the capstan shaft 166, the signals recorded in the tape 152 are erased by the full width head 162, and the rotation head 164 and the audio head 169, a signal is recorded on or reproduced from the tape 152.

At this time, the height of the tape 152 fed out of the cassette 151 is detected by the light emitting diode 170 and the phototransistor 171 which are arranged to face each other with the tape 152 interposed therebetween. The processing is performed by the control circuit 172 (see FIG. 6), and the voice coil motor 173 provided on the reel device 167 is driven to control the height of the reel base 174, whereby the height of the tape 152 fed from the cassette 151 is controlled. Is kept constant.

In this case, the tape height control circuit 172 used in such a tape driving device is provided with a light emitting diode 1 driven by a power supply 175 as shown in FIG.
A preamplifier 176 that amplifies an output signal (detection signal) of the phototransistor 171 that receives the light from 70 via the tape 152, and an inverting amplifier 177 that inverts and amplifies the detection signal output from the preamplifier 176. A low-pass filter 178 for extracting a low-frequency component in the signal output from the inverting amplifier 177; a driving amplifier 179 for amplifying the signal output from the low-pass filter 178 to generate a driving current; After amplifying the detection signal output from the phototransistor 171, the low-frequency component is extracted, and the low-frequency component is amplified to generate a drive current. The tape is supplied to the voice coil motor 173 to keep the height of the tape 152 fed from the cassette 151 constant.

As a result, when the height of the tape 152 fed from the cassette 151 increases,
A drive current is generated by the tape height control circuit 172 in the direction of lowering the drive current. The drive current is supplied to the voice coil motor 173 provided in the reel device 167, and the position of the reel base 174 of the reel device 167 is lowered. The height of the tape 152 is restored.

When the height of the tape 152 fed from the cassette 151 is reduced, a drive current is generated by the tape height control circuit 172 in the direction of raising the tape 152, and the drive current is supplied to the voice provided in the reel device 167. The reel device 1 is supplied to the coil motor 173 and
The position of the reel base 174 at 67 is raised, and the tape 1
The height of 52 is restored.

[0011]

By the way, in the above-mentioned conventional tape driving device, the light emitting diode 170 is used.
And a phototransistor 171 generates a detection signal corresponding to the fluctuation of the tape 152, and drives the voice coil motor 173 provided in the reel device 167 based on the detection signal to generate the detection signal. The reel stand 174 is moved in a direction to reduce the height fluctuation of the tape 152 to keep the tape height constant.

In this case, in the voice coil motor 173 used in such a tape driving device, it is known that the driving current and the generated force have the following relationship.

F = k · B · I (1) where F: force generated in the voice coil motor 173 k: constant caused by the material of the voice coil motor 173 B: magnetic flux linked to the coil of the voice coil motor 173 I: drive current of the voice coil motor 173 The magnetic flux B is a value determined by a magnetization curve specific to the material of the ferromagnetic material used for the voice coil motor 173. Has a hysteresis characteristic.

Further, the relationship between the strength H of the magnetic field and the value of the drive current flowing through the coil is expressed by the following equation.

H = n · I (2) where n is the number of turns of the coil. Therefore, the force F generated in the voice coil motor 173
Becomes a characteristic having a hysteresis characteristic with respect to the value of the drive current.

As apparent from the equations (1) and (2), the hysteresis characteristic determines the magnetization of the coil constituting the voice coil motor 173, and the displacement of the reel base 174 depends on the intensity of the magnetization. Is determined, when the fluctuation of the tape 152 is small, the operation indicates a non-linear operation.

Further, since the intensity of the magnetization of the coil determined by a certain level has a remanence and its operation has a hysteresis characteristic with respect to the value of the driving current, the voice coil as shown in FIG. Even if a triangular drive current is applied to the motor 173, the force F generated in the voice coil motor 173 does not become triangular as shown in FIG. 7B.

For this reason, when the voice coil motor 173 is used, the reel stand 1
In addition to the linear response of the tape 74, there is a problem that the variation in height of the tape 152 cannot be sufficiently reduced due to the hysteresis characteristic of the coil.

In view of the above circumstances, the present invention can improve the non-linear operation of the voice coil motor, and can control the vertical movement of the tape even when the height of the reel base is controlled using the voice coil motor. And a tape drive device using the same, which can linearly control the reel base, thereby sufficiently reducing vertical movement of the tape and stabilizing the tape running. It is intended to be.

[0020]

To achieve the above object, according to the present invention, there is provided a voice coil motor driving apparatus for supplying a driving current to a voice coil motor and driving the same. An AC signal generating section for generating an AC bias signal having a given frequency and level, and a mixing section for generating a new drive current by superimposing the generated AC bias signal on the drive current of the voice coil motor. It is characterized by. According to a second aspect of the present invention, in a tape driving device that controls a height of a tape by using a voice coil motor as a driving source, a tape position detecting unit that detects a height position of the tape and generates a detection signal, A low-frequency component generation unit that generates a low-frequency component for keeping the height of the tape constant, an AC signal generation unit that generates an AC bias signal of a predetermined frequency and level, and a generated AC bias signal. A mixing unit that generates a drive current for the voice coil motor by superimposing the voice coil motor on the low frequency component.

[0021]

In the above configuration, an AC bias signal is generated by an AC signal generating section, and the AC bias signal is superimposed on a driving current of the voice coil motor by the mixing section to drive the voice coil motor.
Even when the height of the reel base is controlled using a voice coil motor, the reel base is linearly controlled with respect to the vertical movement of the tape, thereby reducing the vertical movement of the tape sufficiently and stabilizing the tape running. Let it.

[0022]

FIG. 1 is a block diagram showing an example of a tape running system used in a tape driving device to which an embodiment of a driving device for a voice coil motor according to the present invention is applied.

The tape running system shown in FIG. 1 has a built-in voice coil motor 1 (see FIG. 2). The voice coil motor 1 controls the height of the reel base 2 to feed out the tape 4 in the cassette 3, One reel device 5a for winding, the other reel device 5b for feeding and winding the tape 4 in the cassette 3, and the running of the tape 4 fed from the cassette 3 by the reel devices 5a and 5b. A plurality of posts 6 to 14 for regulating a path, and a tape 4 fed from the cassette 3
A light emitting diode 15 and a phototransistor 16 for detecting the height of the tape 4, a full-width erasing head 17 used when erasing the tape 4 with a full width, an impedance roller 18 for stabilizing the running of the tape 4, a tape 4 while rotating.
A rotary head 19 for recording signals on the tape 4 and reproducing signals from the tape 4, an audio head 20 used for recording and reproducing audio information on the tape 4, and a motor (not shown) And a pinch roller 22 for pressing the tape 4 against the capstan shaft 21.

When recording and reproducing a signal on and from the tape 4 in the cassette 3, the tape 4 is pulled out from the cassette 3 by the posts 6 to 14, and is fed to the full-width erasing head 1.
7, and an impedance roller 18, a rotating head 19,
While being in contact with the audio head 20, the tape 4 is pressed against the capstan shaft 21 by the pinch roller 22, and the reel device 5 a, 5 b and the capstan shaft 21 are rotationally driven to drive the tape 4. A signal recorded in the tape 4 is erased by the full-width erasing head 17, a signal is recorded on the tape 4 by the rotary head 19 and the audio head 20,
To play.

FIG. 2 is a partially cutaway sectional view showing a detailed configuration example of the above-described reel device 5a.

As shown in FIG. 1, the reel device 5a includes a voice coil motor 1 and a DC brushless motor 25.
And a reel base 26. The DC brushless motor 25 rotates and drives the reel base 2 while adjusting the vertical position of the reel base 2 constituting the reel base 26 by the voice coil motor 1. 3 is rotated.

The voice coil motor 1 has an upper plate 28 and a side plate 29, and a cylindrical case 31 having a center rod 30 extending downward at the center lower surface of the upper plate 28;
0, and an axial bearing 3 penetrating a vertical hole formed in the center of the center rod 30.
3 and the axial bearing 33 (FIG. 2).
A thrust shaft 34 slidably supported in the vertical direction (in the vertical direction), a spring 35 supported on one end of the case 31 and biasing the thrust shaft 34 upward, and a predetermined distance below the thrust shaft 34. Two rotating direction bearings 36 and 37 provided at a distance, a slider 38 having an E-shaped longitudinal section attached to the rotating direction bearings 36 and 37, and a slider 38 provided at an outer end portion of the slider 38;
A coil 39 which is paired with the magnet 32 and constitutes a driving unit of the voice coil motor 1. The coil 39 is fixed to the support plate 40, and when the driving current is supplied, the interaction between the coil 39 and the magnet 32 is performed. By moving the slider 38 upward or downward, the rotational bearings 36 and 37 attached to the slider 38 and the thrust shaft 34 are moved upward or downward.

The DC brushless motor 25 includes a plurality of coils 41 concentrically arranged on the support plate 40 with the thrust shaft 34 as a center, and a rotational bearing 42 attached to an upper end of the thrust shaft 34. ,
The thrust shaft 3 is provided by the rotational bearing 42.
A rotating plate 43 rotatably supported with respect to the rotating plate 4; and a plurality of recesses formed below the rotating plate 43. And a plurality of magnets 44 constituting a part, and the vertical position of the rotating plate 43 is regulated by the thrust shaft 34. When a driving current is supplied, the rotation of the rotating plate 4 by the interaction between the coil 41 and the magnet 44.
3 is driven to rotate.

The reel base 26 is made of an elastic plate, and its lower center surface is made up of a bottom plate 45 and an elastic plate fixed to the center of the rotary plate 43, and is arranged to face the bottom plate 45. Upper plate 46, this upper plate 4
A joint 48 having a plurality of columns 47 for connecting the base plate 6 and the bottom plate 45 with a predetermined distance therebetween, and the reel base 2 fixed on the upper plate 46 of the joint 48. The reel base 2 is rotated with the rotation of the rotary plate 43 to rotate the reel 27 of the cassette 3 while swinging the reel base 2 with respect to the rotary plate 43 of the DC brushless motor 25.

FIG. 3 is a block diagram showing an example of a tape height control circuit used in a tape driving device to which an embodiment of the driving device for a voice coil motor according to the present invention is applied.

The tape height control circuit 50 shown in FIG.
A preamplifier 52 for amplifying an output signal (detection signal) of the phototransistor 16 for receiving the light from the tape 4 via the tape 4, an inverting amplifier 53 for inverting and amplifying the detection signal output from the preamplifier 52. , This inverting amplifier 53
A low-pass filter 54 for extracting a low-frequency component in a signal output from
An AC signal generator 55 for generating an AC bias signal having a frequency three to five times the frequency of the signal output from the low-pass filter 54 and an appropriate amplitude, and an output from the AC signal generator 55 And a drive amplifier 57 that amplifies the signal output from the adder 56 and generates a drive current by amplifying the signal output from the adder 56. After amplifying the detection signal output from the phototransistor 16, the low-frequency component is extracted,
After adding an AC bias signal having a preset frequency and amplitude to the low-frequency component, the low-frequency component is amplified and a drive current is generated. The drive current is supplied to the voice coil motor 1 of the reel device 5a. Is kept constant.

As a result, when the height of the tape 4 fed from the cassette 3 is increased, a drive current is generated by the tape height control circuit 50 in the direction of lowering the drive current, which is provided in the reel device 5a. The tape is supplied to the voice coil motor 1 to lower the position of the reel base 2 of the reel device 5a, and the height of the tape 4 is returned to the original height.

At this time, the AC signal generator 55 generates an AC bias signal having a frequency and amplitude that does not affect the running of the tape 4, and outputs the AC bias signal to the low-pass filter 54. Since the drive current is generated by being superimposed on the frequency component, the hysteresis characteristic of the coil 39 constituting the voice coil motor 1 and the AC bias component included in the drive current are obtained according to the same operation principle as that of a normal degaussing head. The amount of vertical displacement of the tape 4 detected by the detection unit constituted by the light emitting diode 15 and the phototransistor 16 and the amount of vertical movement of the tape 4 by the voice coil motor 1 linearly correspond to each other by reducing the influence of the hysteresis characteristics. be able to.

Thus, as shown in FIG. 4, the vertical displacement of the tape 4 when the AC bias signal is applied can be made smaller than the vertical displacement of the tape 4 when the AC bias signal is not applied.

As described above, in this embodiment, the AC signal generator 55 generates an AC bias signal having a frequency and an amplitude that does not affect the running of the tape 4, and outputs the AC bias signal to the low-pass filter 54. Since the drive current is generated by superimposing the drive current on the low-frequency component output from the reel 4, even if the height control of the reel base 2 is performed using the voice coil motor 1, The table 2 can be controlled linearly, whereby the vertical movement of the tape 4 can be sufficiently reduced and the tape running can be stabilized.

In the above-described embodiment, the present invention is described by taking the voice coil motor 1 provided in the reel device 5a of the tape drive as an example. The present invention may be applied not only to the coil motor 1 but also to another high-precision positioning mechanism using a voice coil motor.

[0037]

As described above, according to the present invention, the non-linear operation of the voice coil motor can be improved.
Even when the height of the reel base is controlled using a voice coil motor, the reel base can be linearly controlled with respect to the vertical movement of the tape, thereby sufficiently reducing the vertical movement of the tape. The tape running can be stabilized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an example of a tape traveling system used in a tape driving device to which an embodiment of a voice coil motor driving device according to the present invention is applied.

FIG. 2 is a partially cutaway sectional view showing a detailed configuration example of the reel device shown in FIG. 1;

FIG. 3 is a block diagram showing an example of a tape height control circuit used in a tape driving device to which an embodiment of a voice coil motor driving device according to the present invention is applied;

FIG. 4 is a waveform diagram when tape variation is measured by the driving method of the voice coil motor according to the present invention.

FIG. 5 is a configuration diagram showing an example of a tape traveling system used in a conventionally known tape driving device.

FIG. 6 is a block diagram showing an example of a tape height control circuit used in a conventionally known tape drive.

FIG. 7 is a waveform chart showing an example of control characteristics of the voice coil motor by the tape height control circuit shown in FIG.

[Explanation of symbols]

 Reference Signs List 4 tape 2 reel base 5a reel device 15 light emitting diode 16 phototransistor 50 tape height control circuit 51 power supply 52 preamplifier 53 inverting amplifier 54 low-pass filter 55 AC signal generator 56 adder 57 drive amplifier

Continuation of the front page (56) References JP-A-3-142471 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 15/32 H02K 33/18 H02P 7/00

Claims (2)

(57) [Claims] 1. A voice coil motor driving device for supplying a driving current to a voice coil motor and driving the same, comprising: an AC signal generating unit for generating an AC bias signal having a predetermined frequency and a predetermined level; A mixing unit configured to generate a new driving current by superimposing an AC bias signal on the driving current of the voice coil motor. 2. A tape drive device for controlling a height of a tape by using a voice coil motor as a drive source, a tape position detection unit for detecting a height position of the tape and generating a detection signal, A low-frequency component generation unit that generates a low-frequency component for keeping the height of the tape constant; an AC signal generation unit that generates an AC bias signal having a predetermined frequency and level; A mixing unit that generates a drive current for the voice coil motor by superimposing the low frequency component on the low frequency component.