JPH048169B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field of the Invention> The present invention relates to a microrotation device applied to masks of exposure apparatuses, wafer alignment mechanisms, precision processing machines and measuring machines, semiconductor manufacturing equipment, and the like. <Background of the Invention> Conventionally, as a mechanism for minutely rotating a work table, a mechanism has been used that transmits the rotation of a pulse motor to the table via a worm gear, a feed screw, or the like. However, such a structure is
It is difficult to improve the rotational accuracy and resolution of the table due to the backlash of gears and screws, the rotational resolution of the pulse motor, etc., and the accuracy of 1 to 2 seconds is the limit. Moreover, the mechanism is complicated and the external size is increased, and in particular, there are many problems such as increased weight of the rotating part and slow response speed. The present invention utilizes the expansion and contraction of a piezoelectric element such as a piezo element as a drive source for micro-rotation, thereby solving all the conventional problems at once, and creating a novel system that can speed up response speed and improve rotational accuracy and resolution. This provides a micro rotation device. <Description of Embodiments> The micro-rotating device of the present invention has a recess 11 having a circular planar shape and an arbitrary depth on the upper surface of a base 1, and a device such as a piezo element that is applied to the recess 11 by applying a voltage to the recess 11. The rotary drive mechanism 2 is equipped with a piezoelectric element that expands and contracts as the drive source. The drive mechanism 2 is constructed by fitting into the recess 11 a pair of elastic rings 2a and 2b stacked vertically. Each of the elastic rings 2a and 2b is provided with a thin walled portion 21 in the middle of its circumferential length so as to be able to pivot.
A substantially horseshoe-shaped ring base material 20 is formed with 2 and 23 facing each other, and piezoelectric elements 24a and 24b are integrated between the end surfaces 22 and 23. A piezoelectric element 24a, which is loosely fitted in the piezoelectric element 11 and is applied with a voltage,
By expanding 24b, the outer diameter is expanded and fixed to the inner surface of the recess 11 by pressure. On the inner peripheral surface of each elastic ring 2a, 2b, an upper ring 2a, a lower ring 2a,
Support pieces 25a protruding from 2b and facing each other,
25b, 25a, 25b are provided symmetrically, piezoelectric elements 26a, 26b for rotational driving are attached to both supporting pieces 25a, 25a of the upper ring 2a, respectively, and the tip surfaces are magnetically attracted to both supporting pieces 25b, 25b of the lower ring 2b. The piezoelectric elements 26a, 26b are connected to each other through coupling rings 27, 27 so as to be slidable in the plane.
are normally contracted, and when expanded by voltage application, press the supporting pieces 25b, 25b, respectively. Although not shown in the drawings, in actual practice, a pressure air bearing or other bearing may be provided on the inner surface of the recess 11 of the base 1 to improve the lubricity between the rings. However, during the rotation operation, in the initial state, a voltage is applied to both piezoelectric elements 24a and 24b to cause them to expand, and the upper and lower elastic rings 2a and 2b are brought into pressure contact with the inner surface of the recess 11 and fixed to the base 1. At this time, the rotating piezoelectric elements 26a and 26b are kept in a contracted state. During minute rotation, the piezoelectric elements 24a of the upper elastic ring 2a are first contracted to release the pressure contact between the piezoelectric elements 24a and the base 1, and then when the rotating piezoelectric elements 26a, 26b are extended, the piezoelectric elements 26a, 26b are used as supporting pieces. 25b, the lower elastic ring 2b is pressed by the amount of expansion of the piezoelectric element, and the lower elastic ring 2
b is fixed to the base 1, and the upper elastic ring 2a is in a free state, so the elastic ring 2a slightly rotates in the counterclockwise direction. Next, after fixing the upper elastic ring 2a to the base 1 and releasing the fixation of the lower elastic ring 2b, the rotating piezoelectric elements 26a, 26b are fixed.
By contracting, the lower elastic ring 2b rotates slightly in the same direction as the upper ring 2a, and then the lower elastic ring 2b is fixed to the base 1. The above sequence is shown in the table below.

【table】

[Table] However, +...Extends the piezoelectric element -...Retracts the piezoelectric element Next, the steps for slightly rotating the piezoelectric element in the clockwise direction are as follows.

[Table] The above micro-rotational movements in the forward and reverse directions allow precise positioning at any rotational angle. <Effects of the Invention> As described above, the present invention provides vertically stacked elastic rings in the circular recess formed in the base, and each elastic ring incorporates a piezoelectric element that is fixed to or released from the base, and Rotating piezoelectric elements are inserted between the rings to press the rings against each other in the circumferential direction, and minute rotation is achieved by controlling the expansion and contraction of each of the piezoelectric elements. This invention has the effect of simplifying the structure and achieving the purpose of the invention, such as miniaturizing the device, increasing response speed, and further improving rotation accuracy and resolution.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment, and FIG. 2 is a plan view showing one embodiment.
It is a sectional view along the figure A-A line. DESCRIPTION OF SYMBOLS 1... Base, 11... Recessed part, 2... Rotation drive mechanism, 2a... Upper elastic ring, 2b... Lower elastic ring, 24a, 24b... Fixing piezoelectric element,
26a, 26b...Rotating piezoelectric elements.

Claims (1)

[Claims] 1. A base in which a circular recess is formed, a pair of elastic rings stacked and arranged in the recess of the base, and an expandable piezoelectric element incorporated in each ring and fixed to or released from the base by expanding or contracting its outer diameter. , consisting of a rotating piezoelectric element that is interposed between the upper and lower rings and presses and moves the corresponding ring in the circumferential direction, and is characterized in that the elastic ring is minutely rotated by controlling the expansion and contraction movements of each of the piezoelectric elements. Micro-rotating device.