Linear driving device

Claim 1

A linear driving device comprising: a hydrostatic gas bearing; a shaft supported by said bearing, wherein said bearing and said shaft are both disposed within a voice-coil motor, wherein said shaft moves in a direction of movement in response to actuation of the voice-coil motor; and a locking mechanism for constraining the movement of said shaft in its direction of movement, wherein said locking mechanism comprises an air cylinder, and wherein a member is fixed to the side of said shaft, and wherein said air cylinder is fixed to said shaft and clamps the member fixed to the side of said shaft when the supply of a pressurized gas to said hydrostatic gas bearing is stopped.

Claim 11

An apparatus for use in a linear driving device having a voice-coil motor for driving a shaft supported by a hydrostatic bearing, both disposed within the voice-coil motor, said apparatus comprising: a locking mechanism for constraining the movement of the shaft in its direction of movement, wherein said locking mechanism comprises an air cylinder, wherein a member is fixed to the side of the shaft, and wherein said air cylinder is fixed to the shaft and clamps the member fixed to the side of the shaft when the supply of a pressurized gas to the hydrostatic gas bearing is stopped.

Claim 12

An apparatus for use in a linear driving device having a voice-coil motor for driving a shaft supported by a hydrostatic bearing, both disposed within the voice-coil motor, said apparatus comprising: a locking mechanism for constraining the movement of the shaft in its direction of movement, wherein said locking mechanism comprises an air cylinder, wherein a member is fixed to the side of the shaft, and wherein said air cylinder is fixed to the shaft and clamps the member fixed to the side of the shaft when the supply of a pressurized gas to the hydrostatic gas bearing is stopped.

Claim 17

An apparatus for use in a linear driving device having a voice-coil motor, including a coil assembly forming a closed space surrounded by a coil, for driving a shaft supported by a direct-acting bearing to position the shaft in a predetermined position, said apparatus comprising: a wall having one side facing the closed space and another side facing the outside of the linear driving device, wherein said wall has a plurality of exhaust holes therein connecting the closed space with the outside, wherein the conductance, C 2 , of each of the plurality of exhaust holes satisfies the following equation and inequality: C.sub.2 =QL/Δx and Δx<x.sub.0, where Q is the quantity of flow of gas corresponding to a change in volume of the closed space per unit time, L is the length of the closed space in the axial direction, Δx is the amount of displacement of said coil and said shaft in the axial direction due to a force caused by a pressure change within the closed space due to the exhaust of the quantity of flow of gas Q from the exhaust hole, and x 0 is the permissible value of vibration in the axial direction.

Claim 18

An apparatus for use in a linear driving device having a voice-coil motor, including a coil assembly forming a closed space surrounded by a coil, for driving a shaft supported by a direct-acting bearing to position the shaft in a predetermined position, said apparatus comprising: a wall having one side facing the closed space and another side facing the outside of the linear driving device, wherein said wall has a plurality of exhaust holes therein connecting the closed space with the outside, wherein the conductance, C 2 , of each of the plurality of exhaust holes satisfies the following equation and inequality: C.sub.2 =QL/Δx and Δx<x.sub.0, where Q is the quantity of flow of gas corresponding to a change in volume of the closed space per unit time, L is the length of the closed space in the axial direction, Δx is the amount of displacement of said coil and said shaft in the axial direction due to a force caused by a pressure change within the closed space due to the exhaust of the quantity of flow of gas Q from the exhaust hole, and x 0 is the permissible value of vibration in the axial direction.

Claim 19

An apparatus for use in a linear driving device having a voice-coil motor, including a coil assembly forming a closed space surrounded by a coil, for driving a shaft supported by a direct-acting bearing to position the shaft in a predetermined position, said apparatus comprising: a wall having one side facing the closed space and another side facing the outside of the linear driving device, wherein said wall has a plurality of exhaust holes therein connecting the closed space with the outside, wherein the shape, the size, and the number of said exhaust holes are within a range so that a relationship of f>2f 0 holds between the natural frequency f of a system comprising the coil of the voice-coil motor, the direct-acting bearing, and the shaft supported by the direct-acting bearing, and the control frequency f 0 .

Claim 20

An apparatus for use in a linear driving device having a voice-coil motor, including a coil assembly forming a closed space surrounded by a coil, for driving a shaft supported by a direct-acting bearing to position the shaft in a predetermined position, said apparatus comprising: a wall having one side facing the closed space and another side facing the outside of the linear driving device, wherein said wall has a plurality of exhaust holes therein connecting the closed space with the outside, wherein the shape, the size, and the number of said exhaust holes are within a range so that a relationship of f>2f 0 holds between the natural frequency f of a system comprising the coil of the voice-coil motor, the direct-acting bearing, and the shaft supported by the direct-acting bearing, and the control frequency f 0 .