JP2797679B2 - Head positioning device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head positioning device used for a disk device such as a floppy disk device, a hard disk device, and an optical disk device.

2. Description of the Related Art In recent years, as the track density of disk devices such as floppy disk devices and hard disk devices has been increasing,
High accuracy of the head positioning control is a major issue. In recent years, personal computers and word processors have become thinner and more weighed, and portable A4-size computers have been commercialized. Since they are used in environments with large external vibrations such as in automobiles and trains, the head positioning devices of the disk drives mounted on them are thin and lightweight, and have high precision even when external vibration is applied. Head positioning control must be possible.

Hereinafter, an example of a conventional head positioning device will be described with reference to the drawings. FIG. 3 is an exploded perspective view of a conventional head positioning device, and FIG. 4 is a plan view. 70
Is a floppy disk, and 71 is the disk rotation center of the floppy disk 70. Numeral 72 denotes a side φ head, which is attached to the side φ head arm 90. The arrow 75 indicates the direction in which the side φ head 72 is driven, and indicates the direction passing through the disk rotation center 71 in parallel with the floppy disk 70. A side 1 head arm 80 is fixed at a position where the side 1 head 91 faces the side φ head 72. Side 1 head arm 80 is a hinge spring
It is attached to the side φ head arm 90 by screws 83a and 83b together with the fixing plate 82 via 81. 84 is side 1
Head 91 with floppy disk 70 and side φ head
A head load spring that presses against the 72
The projection 85 is fixed on the projection 82, and the end of the projection 85 is pressed against the side 1 head arm 80. Reference numeral 80 denotes a linear guide, and a movable portion 87 and a fixed portion 88 of the linear guide 86 are provided with a V-shaped guide groove 98 extending in the longitudinal direction, between which a plurality of balls (not shown) are rolled. It is sandwiched freely. The movable part 87 has a side φ head arm with screws 89a, 8
Fixed by 9b. The fixing portion 88 is fixed to the chassis 77 by screws (not shown) with the direction in which the guide groove 98 is provided being parallel to the direction of the arrow 75. The movable portion 87 can reciprocate linearly in parallel with the direction of the arrow 75 with the rolling of the ball sandwiched between the guide grooves 98. Reference numeral 76 denotes a motor coil, which is fixed to the side φ head arm 90 in a state of being wound in a direction perpendicular to the direction of arrow 75. Reference numerals 78a, 78b, 78c, and 78d denote motor yokes, which are attached to the chassis 77. , 79a, 79b are magnets, which are fixed to motor yokes 78a, 78c, respectively. A magnetic circuit is formed by the motor yokes 78a and 78b and the magnet 79a, and the motor yokes 78c and 78d and the magnet
A magnetic circuit is constituted by 79b, and the magnet 79
A part of the motor coil 76 exists in a gap between the motor coils 76a and 79b and the motor yokes 78a and 78c opposed thereto, and a magnetic field in a direction perpendicular to the winding direction of the motor coil 76 is formed. The head carriage includes a side 1 head arm 80, a movable portion 87 of a linear guide 86, etc., which includes a motor coil 76 and is driven integrally with the side φ head arm 90.
The motor yoke 78a, 78b, 78c, 78d, the magnets 79a, 79b, and the motor coil 76 form a linear motor that drives the head carriage 73.

The operation of the head positioning device configured as described above will be described below. When a current is applied to the motor coil 76, an electromagnetic force acts on the motor coil 76 in the direction of the arrow 75 in the direction determined by the direction of the flowing current by the magnetic field generated by the magnetic circuits 79a and 79b. With this electromagnetic force, the head carriage 73 moves the linear guide 86
While being guided by, it is linearly driven in the direction of arrow 75,
Side φ head arm 90 and side φ head 72 and side 1 head fixed to side 1 head arm 80, respectively
The reference numeral 91 is positioned on a target track on the floppy disk 70 by controlling the direction and magnitude of the current flowing through the motor coil 76.

However, in the above-described configuration, when vibration is applied in a direction parallel to the direction of arrow 75, motor coil 76 driven integrally with side φ head arm 90, side 1 head The head carriage 73 including the arm 80, the movable portion 87 of the linear guide 86, the motor 76, and the like has an inertial force F1 (FIG. 4) obtained by multiplying the total mass of the head carriage 73 by the acceleration of the vibration. Acts in the direction of arrow 75. The side φ head 72 and the side 1 head 91 whose positioning is controlled to the target track are displaced by the inertia force F1 together with the head carriage 73 by an amount determined by the relationship between the control performance and the magnitude of the inertia force, and the displacement amount is large. In this case, a read / write error occurs. Therefore, in the head positioning device having the conventional configuration, in order to prevent a read / write error from occurring even when the applied vibration is large, a motor having a driving force sufficiently larger than an inertial force applied by the vibration is required, and , Very high control performance is required.

In view of the above problems, the present invention provides a head positioning device capable of performing high-precision positioning even when a large vibration or impact is applied, without requiring an improvement in driving force of a motor or an improvement in control performance. To provide.

Means for Solving the Problems In order to solve the above problems, a head positioning device according to the present invention includes a head carriage provided with a head for writing or reading information on an information recording medium; and A linear motor that generates a driving force for linear driving, a transmission mechanism that converts the driving force into a force in a substantially opposite direction and transmits the force to the head carriage, and a linear motion guide mechanism that guides the head carriage. A head positioning device in which the head carriage is driven by the driving force in a direction substantially opposite to a moving direction of the mover of the linear motor, wherein a mass ratio of the head carriage to the mover is less than 1; Wherein the mass ratio is approximately equal to the reciprocal of the speed ratio of the head carriage to the mover. In the head positioning device of the present invention, the first and second pinions are coaxially and integrally rotatably provided with each other, and are fixed to the movable element of the linear motor by meshing with the first pinion. A transmission mechanism is constituted by a first rack and a second rack fixed to the head carriage by meshing with the second pinion.

According to the present invention, the driving force of the linear motor acting on the mover of the linear motor is substantially opposite to the driving force of the linear motor via the first and second racks and the first and second pinions. And transmitted to the head carriage at a certain speed ratio. When vibration is applied to the head positioning device of the present invention in a direction parallel to the direction in which the head carriage is driven, the movable element and the head carriage have an inertial force parallel to the direction of vibration. Acts according to the direction of vibration. Of these inertial forces, the inertial force acting on the mover is transmitted through the first and second racks and the transmission mechanisms such as the first and second pinions at a speed ratio substantially opposite to each other. It is converted and transmitted to the head carriage. The magnitude of the force is given by the product of the magnitude of the inertial force acting on the mover and the reciprocal of the speed ratio of the transmission mechanism. Also, since the magnitude of the inertial force acting on the object is proportional to its mass, the mass ratio of the head carriage to the mass of the mover,
If the reciprocal of the speed ratio of the head carriage with respect to the speed of the mover is made equal, the inertial force applied to the mover is transmitted by the first and second racks and the transmission mechanism such as the first and second pinions. The force transmitted to the head carriage after being converted and the inertial force acting on the head carriage itself cancel each other out.

Here, if the speed ratio of the head carriage to the speed of the mover is 1, the mass of the mover and the head carriage must be equal to each other if the mass of the mover and the head carriage is equal to each other. You can't reduce the power to run to zero. Therefore, for example, when the mass of the mover is larger than the mass of the head carriage, it is necessary to add a balance weight or the like to the head carriage to increase the mass, and the head carriage driven by the linear motor and The entire mass of the mover increases, and high-speed driving becomes impossible unless the force generated by the linear motor is increased. However, according to the configuration of the present invention, even when the mass ratio of the head carriage to the mover is less than 1, for example, when the mass of the mover is twice the mass of the head carriage, the speed ratio as the transmission mechanism is reduced. The use of a 1/2 rack and pinion makes it possible to reduce the force acting on the head carriage when vibration is applied without adding a balance weight or the like. Further, at this time, the driving force transmitted to the head carriage via the transmission mechanism is larger than the generated force of the linear motor by an inverse multiple of the speed ratio. Therefore, the generation force is small,
Even if a smaller motor is used, a sufficiently large driving force can be obtained with respect to the driving resistance such as the frictional force of the linear motion guide mechanism, enabling higher-speed driving and preventing the head resistance from deteriorating due to the driving resistance. be able to. Further, it is also possible to reduce the supply current to the linear motor and reduce the power consumption.

As described above, according to the configuration of the present invention, even if vibration is applied, the head is not displaced from the target track, and a small and high-precision head positioning device capable of high-speed driving can be realized.

Embodiment A head positioning device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view of a head positioning device according to one embodiment, and FIG. 2 is a plan view. Reference numeral 10 denotes a floppy disk, and 11 denotes a disk rotation center of the floppy disk 10. Reference numeral 12 denotes a side φ head, which is attached to the side φ head arm 46. An arrow 15 indicates a direction in which the side φ head 12 is driven, and indicates a direction passing through the disk rotation center 11 in parallel with the floppy disk 10. A side 1 head arm 20 is fixed at a position where the side 1 head 51 faces the side φ head 12. Side 1 head arm 20
Are screws 23a and 23b together with the fixing plate 22 through the hinge spring 21.
Attached to the side φ head arm 46. Numeral 24 denotes a head load spring for pressing the side 1 head 51 together with the floppy disk 10 against the side φ head 12, and is fixed to a projection 25 provided on the fixing plate 22, and one end thereof is connected to the side 1 head arm 20. Is pressed against. Reference numeral 26 denotes a linear guide A, and a movable portion A27 and a fixed portion A28 of the linear guide A26 are provided with a V-shaped guide groove 38 extending in the longitudinal direction, between which a plurality of balls (not shown) are provided. Rolled freely. A side φ head arm 46 is fixed to the movable portion A27 by screws 29a and 29b. The fixing portion A28 is fixed to the chassis 17 by screws (not shown) in a state where the direction in which the guide groove 38 is provided is parallel to the direction of the arrow 15. The movable portion A27 reciprocates linearly in parallel with the direction of the arrow 15 with the rolling of the ball sandwiched between the guide grooves 38. Therefore, the side φ head 12,
Side 1 head 51, side φ head arm 46, side 1
The head carriage 13 including the head arm 20, the fixed plate 22, and the movable portion A27 can reciprocate linearly in parallel with the direction of the arrow 15 while being guided by the linear guide A26.

Reference numeral 16 denotes a motor coil, which is fixed to the coil bobbin 30 while being wound in a direction perpendicular to the direction of the arrow 15.
Reference numerals 18a, 18b, 18c, and 18d denote motor yokes, which are attached to the chassis 17. 19a and 19b are magnets, which are fixed to the motor yokes 18a and 18b, respectively. A magnetic circuit a is formed by the motor yokes 18a, 18c, 18d and the magnet 19a, and a magnetic circuit b is formed by the motor yokes 18b, 18c, 18d and the magnet 19b, and the magnets 19a, 19b and the motor yoke 18c opposed thereto are formed. A part of the motor coil 16 is present in the gap between them, and a magnetic field in a direction perpendicular to the winding direction of the motor coil 16 is formed. Numeral 40 denotes a linear guide B having a structure similar to that of the linear guide A26.
a, 42b fixed. The fixing portion B43 is fixed to the chassis 17 by screws (not shown) with the direction in which the guide groove is provided being parallel to the direction of the arrow 15.
Therefore, the movable portion B41 can reciprocate linearly in parallel with the direction of the arrow 15 integrally with the motor coil 16 and the coil bobbin 30. These motor yokes 18a, 1
8b, 18c, 18d, magnets 19a, 19b, and motor coil
A linear motor 44 is constituted by the coil bobbin 30, the linear guide 40, and the linear motor 44. The linear motor 44 includes the motor coil 16, the coil bobbin 30, and the linear guide 40.
The movable element 45 composed of the movable section B41 is driven.

Pinion B57 and Pinion C58 are coaxial and integrally configured,
It is rotatably provided on the chassis 17. Also a pinion
The modules of B57 and Pinion C58 are equal, and the ratio of the number of teeth is
2: 1. The rack B59 is provided on the coil bobbin 30 of the mover 45 in parallel with the arrow 15, and meshes with the pinion B57. The rack C60 is a side φ head arm 46 of the head carriage 13.
Is provided in parallel with the arrow 15 and meshes with the pinion C58.

The operation of the head positioning device according to one embodiment of the present invention configured as described above will be described below. When a current is applied to the motor coil 16, the motor coil
16 moves the mover 4 while being guided by the linear guide B40.
5 is linearly driven in the direction of arrow 15 together with the coil bobbin 30 and the movable portion B41 of the linear guide B40. Mover 4
The driving force of the linear motor 44 acting on 5 is transmitted to the pinion B57 via the rack B59, and the pinion B57 rotates integrally with the pinion C58. Further linear motor 4
The driving force of No. 4 is transmitted to the rack C60 via the pinion C58. Here, the modules of the pinion B57 and the pinion C58 are equal, and the ratio of the number of teeth is 2: 1.
7, the speed ratio of the transmission mechanism composed of the pinion C58, the rack B59, and the rack C60 is 1/2, and the rack B59 is the pinion B57, and the rack C60 is the 0 pinion C58 and the rotation axis of the pinion. They are engaged at opposite positions. Therefore, a force in the opposite direction is transmitted to the head carriage 13 via the transmission mechanism at a magnitude twice the driving force of the linear motor 44, and the head carriage 13 is moved to the linear guide A2.
While being guided by 6, the movable element 45 is driven by a half of the moving distance of the movable element 45 in a direction parallel to the direction of the arrow 15 and opposite to the direction in which the movable element 45 is driven. Therefore, the side φ head arm 46, the side φ head 12 and the side 1 head 51 fixed to the side 1 head arm 20, respectively, control the direction and magnitude of the current flowing through the motor coil 16 to control the movement of the mover 45. By controlling the direction and the amount of movement, the target track on the floppy disk 10 is positioned.

Here, in the head positioning device according to the embodiment of the present invention, when vibration is applied in a direction parallel to the direction in which the head carriage 13 is driven (that is, the direction of arrow 15),
Inertia forces F1 and F2 (FIG. 2) parallel to the direction of vibration act on the mover 45 and the head carriage 13 according to the direction of vibration. Of these inertial forces, the inertial force F1 acting on the mover 45 is transmitted to the pinion B57 via the rack B59, and is transmitted to the head carriage 13 via the pinion C58 and the rack C60. At this time, since the speed ratio of the transmission mechanism is 、, the force F3 (= −2F1), which is twice as large in the opposite direction, is transmitted to the head carriage 13. Here, the magnitude of the inertial force F1 acting on the mover 45 is determined by the mass of the mover 45, and the inertial force F2 acting on the head carriage 13 is determined.
Is also determined by the mass of the head carriage 13. Therefore, the total mass of the head carriage 13 including the side φ head 12, the side 1 head 51, the side φ head arm 46, the side 1 head arm 20, the fixed plate 22, and the movable portion A27 is reduced by the mass of the movable element 45. If it is doubled, the inertia force F2 applied to the head carriage 13 becomes twice as large as the inertia force F1 applied to the mover 45 (F2 = 2F1). Therefore mover 4
Since the inertia force F1 acting on 5 is converted by the transmission mechanism and transmitted to the head carriage 13 and the inertia force F2 directly acting on the head carriage 13 have substantially the same magnitude and opposite directions, they are forces. Therefore, the resultant force of the forces acting on the head carriage 13 is almost zero. Therefore, if the product of the mass of the mover 45 and the reciprocal of the speed ratio of the transmission mechanism is equal to the mass of the head carriage 13, the resultant of the forces acting on the head carriage 13 will be substantially zero. In other words, if the mass ratio of the head carriage 13 to the mass of the mover 45 is made equal to the reciprocal of the speed ratio of the transmission mechanism, the effect of external vibration on the head carriage 13 can be made substantially zero.

As described above, according to the configuration of the embodiment of the present invention, the mover
By making the mass ratio of the head carriage 13 to the mass of the mass 45 and the reciprocal of the speed ratio of the transmission mechanism (the speed ratio of the head carriage 13 to the speed of the mover 45) substantially equal, the vibration of the head carriage Since the force acting on the head can be made substantially zero, the head does not displace from the target track, and the head can be positioned with high accuracy without requiring high control performance. Here, if the speed ratio of the head carriage 13 to the speed of the mover 45 is 1, the mover 45 and the head carriage 13
If the mass of the head carriage 13 is not made equal, the force acting on the head carriage 13 when vibration is applied cannot be reduced to zero. In general, the head carriage 13 is made of a material having a relatively small specific gravity, such as resin, to reduce the weight.
On the other hand, a copper wire having high conductivity is
Since the specific gravity of the copper wire is large, the mover 45 tends to have a larger mass than the head carriage 13. Therefore, when the speed ratio of the head carriage 13 to the speed of the mover 45 is set to 1, it is necessary to add a balance weight to the head carriage 13 to make the masses of the mover 45 and the head carriage 13 equal. That is, the entire mass of the head carriage 13 and the mover 45 driven by the linear motor 44 increases, and high-speed driving becomes impossible unless the force generated by the linear motor 44 is increased.

However, as in the embodiment of the present invention, the mass ratio of the head carriage 13 to the mover 45 is less than 1, for example,
Even if the mass of the head carriage 13 is twice as large as the mass of the head carriage 13, if a rack pinion having a speed ratio (the ratio of the speed of the head carriage 13 to the speed of the mover 45) of 1/2 is used as the transmission mechanism, a balance weight, etc. The force acting on the head carriage 13 when vibration is applied can be reduced to zero without adding.

Further, a force twice as large as the force generated by the linear motor 44 is transmitted to the head carriage 13. Therefore, even if a smaller motor that generates a small force is used, a sufficiently large driving force can be obtained with respect to the driving resistance, such as the frictional force of the linear guide A26, and higher-speed driving can be performed. Accuracy can be prevented from deteriorating. It is also possible to reduce the current supplied to the linear motor 44 and reduce the power consumption. That is, a small-sized, low-power-consumption, and high-accuracy head positioning device can be realized.

The reciprocal of the mass ratio of the head carriage 13 to the mass of the mover 45 and the reciprocal of the speed ratio of the transmission mechanism are configured to be substantially equal, but in the configuration of the present invention, the resultant force acting on the head carriage 13 is the mass of the head carriage 13 From, mover
Since the product of the mass of 45 and the reciprocal of the speed ratio of the transmission mechanism is equal to the inertial force acting on the mass component, even if it is impossible to make them exactly equal, make them as equal as possible As a result, the force acting on the head carriage 13 is smaller than in the conventional configuration, and the influence of disturbance vibration can be reduced.

Effect of the Invention As described above, the head positioning device of the present invention includes a transmission mechanism that converts a driving force of a linear motor that linearly drives a head carriage into a force in a substantially opposite direction and transmits the force to the head carriage, and a head carriage. A linear motion guide mechanism for guiding, wherein the head carriage is driven by the driving force in a direction substantially opposite to a moving direction of the mover of the linear motor, wherein the head carriage with respect to the mover is provided. And the mass ratio is less than 1, and the mass ratio is substantially equal to the reciprocal of the speed ratio of the head carriage to the mover. With this configuration, the inertia force acting on the mover when vibration is applied from the outside is converted into a force in the opposite direction by the transmission mechanism and transmitted to the head carriage. At this time, since the mass ratio of the head carriage to the mover is set substantially equal to the reciprocal of the speed ratio of the head carriage to the mover, the inertia of the mover converted in a direction opposite to the inertia force applied to the head carriage itself. The forces cancel each other, and the resultant force acting on the head carriage can be reduced to about 0 without adding a balance weight or the like. Further, since the mass ratio of the head carriage to the mover is less than 1,
The speed ratio of the head carriage to the speed of the mover is also less than 1, and the power generated by the linear motor can be amplified and transmitted to the head carriage. Therefore, even if a smaller linear motor is used, high-speed driving and high-precision positioning of the head carriage can be performed.

A first rack fixed to a movable element of a linear motor, the first and second pinions having transmission mechanisms coaxially and rotatably provided integrally with each other; In the head positioning device composed of the second pinion and the second rack fixedly engaged with the head carriage, the speed ratio of the head carriage to the mover is arbitrarily determined by the ratio of the number of teeth of the second pinion to the first pinion. Is decided. Therefore, it is easy to set the mass ratio of the head carriage to the movable element and the reciprocal of the speed ratio to be equal only by changing the tooth number ratio. Therefore, it is possible to easily realize a head positioning device capable of high-speed driving and high-precision positioning of the head carriage.

As described above, according to the configuration of the present invention, even if vibration is applied, the head is not displaced from the target track, and a compact and high-precision head positioning device capable of high-speed driving can be realized.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a head positioning device according to an embodiment of the present invention, FIG. 2 is a plan view of the head positioning device, and FIG.
FIG. 1 is a perspective exploded view of a conventional head positioning device, and FIG. 4 is a plan view of the same head positioning device. 12: Side φ head head, 13: Head carriage, 26: Linear guide A, 40: Linear guide B, 44
... linear motor, 45 ... mover, 57 ... pinion B, 58 ... pinion C, 59 ... rack B, 60 ... rack C.

Claims (2)

(57) [Claims] A head carriage provided with a head for writing or reading information on or from an information recording medium; a linear motor for generating a driving force for linearly driving the head carriage; A transmission mechanism that converts the force into an opposite direction and transmits the force to the head carriage, and a linear motion guide mechanism that guides the head carriage, wherein the driving force causes the head carriage to move with the moving direction of the mover of the linear motor. A head positioning device driven in substantially the opposite direction, wherein a mass ratio of the head carriage to the mover is less than 1, and the mass ratio is substantially equal to a reciprocal of a speed ratio of the head carriage to the mover. A head positioning device characterized by the above-mentioned. 2. A first rack fixed to a mover of a linear motor, the first and second pinions being coaxially and integrally rotatably provided with each other, and being engaged with the first pinion. 2. The head positioning device according to claim 1, further comprising a second rack fixed to the head carriage in mesh with the second pinion.