JPH10222849A - Precise feed unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precise feed unit strong for a disturbance and suppressing a peak value of a gain appearing due to the specific frequency of vibration in a mechanical system. SOLUTION: A movable part 4 runs along a guide 3 by drive force of a linear motor coil 5 supported in a linear motor magnetic circuit 6, and vibrative transmission between the movable part 4 and an optical system base 11 is suppressed by damping material 10 provided between the movable part 4 and the optical system base 11, and the peak value of the gain appearing due to the specific frequency of vibration in the mechanical system is reduced, and the constitution strong for the disturbance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision feed unit, and more particularly to an air slide which is driven by an actuator and travels in a non-contact manner along a guide member. The present invention relates to a precision feed unit that performs feedback control of an actuator and performs precise positioning of an optical component or the like attached to a movable portion of an air slide.

[0002]

2. Description of the Related Art In recent years, the recording density of optical disks has been increasing. For example, CD (Compact Disc)
As the technology advances from DVD to digital video disk (DVD), the recording capacity of DVD is 6 times larger than that of CD.
Aiming for three times D.

As described above, as the density of optical discs increases, the track pitch also decreases, and there is a demand for minimizing the feed error of the precision feed unit. Therefore,
During the mastering process, if any disturbance enters and the movable portion of the feed unit vibrates, the master disk may be defective.

FIG. 3 is a side view showing an example of a conventional precision feed unit. In FIG. 3, a support 2 is provided on a base plate 1.
The guide 3 having a rectangular cross-section is fixed via the. The movable part 4 has a mouth-shaped cross section, and its inner surface faces four surfaces of the guide 3 via a bearing gap.
By supplying compressed air from inside to the bearing gap, it is supported in a non-contact manner and constitutes an air slide. The linear motor coil 5 is attached to the lower surface of the movable part 4 and the base plate 1
Are supported in a non-contact manner in a linear motor magnetic circuit 6 attached to the motor.

When a current flows through the linear motor coil 5, a force is generated in the guide direction, and the movable section 4 is driven.
A scale 7 is mounted on a side surface of the movable part 4 via a scale mount 8, and the displacement of the movable part 4 is measured by a scale head 9 mounted on the base plate 1. This displacement signal is fed back, and a deviation signal from the target position is given to the linear motor coil 5, thereby forming a feedback control system. Further, the optical system base 11 is integrally attached to the upper surface of the movable part 4,
An optical system base 11 is provided with an optical system component 12 for optical disk mastering.

[0006]

The air slide shown in FIG. 3 has low friction by supporting the movable portion 4 in a non-contact manner with respect to the guide 3, so that no stick-slip occurs when the movable portion 4 is driven. Although it has been used for precision positioning because of its advantages, it is a non-contact support, so its damping ability is small, and as the requirements for positioning errors become strict, micro-vibration due to disturbances becomes a problem. Thus, it has become necessary to maintain the high accuracy of the air slide and to withstand vibration.

In particular, when the frequency is equal to the natural frequency of the mechanical system, the amplitude increases due to resonance, and it is necessary to increase the damping ability at the natural frequency. For that purpose, it is necessary to suppress the peak value of the gain appearing at the natural frequency of the mechanical system when measuring the loop transfer function of the system.

FIG. 4 is a diagram showing a loop transfer function of a conventional precision feed unit. In particular, (a) shows a gain characteristic,
(B) shows phase characteristics. As shown in FIG. 4A, a gain peak exists near 1600 Hz (point A), which is the natural frequency of the mechanical system. As a method of reducing the peak value of the gain, a method of increasing the rigidity of the mechanical system and increasing the natural frequency can be considered, but there is a limit due to the longitudinal elastic modulus of the material and the size and weight of the device.

Also, by inserting a notch filter in the frequency range corresponding to the peak frequency in the control system,
The gain at the peak frequency can be reduced, but in this case, if the mass changes by replacing the optical head or the like attached to the movable section 4 of the feed unit, the natural frequency of the mechanical system changes, and the effect of the notch filter is reduced. There is a disadvantage that it cannot be obtained.

SUMMARY OF THE INVENTION Therefore, a main object of the present invention is to provide a precision feed unit which reduces a peak value of a gain appearing at a natural frequency of a mechanical system and is resistant to disturbance.

[0011]

The invention according to claim 1 is
In the precision feed unit driven by the actuator, the air slide travels along the guide member in a non-contact manner, and performs precise positioning of the component attached to the movable section of the air slide, a component constituting the movable section of the air slide; The vibration damping material is inserted between any two of the components that are integrally attached to the movable part.

In the invention according to the second aspect, the position of the air slide according to the first aspect is detected by the displacement sensor, and the actuator is feedback-controlled based on the detected output.

In the invention according to claim 3, the vibration damping material according to claim 1 is a viscoelastic vibration damping material having a thickness of several hundred μm or less.

According to a fourth aspect of the present invention, the damping material according to the first aspect is a damping steel sheet having a thickness of several hundred μm or less.

[0015]

FIG. 1 is a side view showing an embodiment of the present invention. In the precision feed unit shown in FIG. 1, the optical system base 11 described with reference to FIG. 3 is integrally attached to the upper surface of the movable section 4 via the vibration damping material 10, and the other components are the same as those shown in FIG. Is the same as Damping material 10
For example, a viscoelastic body such as rubber or plastic having a thickness of several hundred μm or less is used.

When the thickness of the viscoelastic body is large, the straightness accuracy of the air slide may be adversely affected.
When a vibration damping material of 0 μm or less is used, relative movement between the two parts due to deformation of the viscoelastic body can be suppressed to a small extent, and deterioration of straightness accuracy, which is the greatest feature of an air slide, can be minimized. .

FIG. 2 shows a loop transfer function according to an embodiment of the present invention. In particular, FIG.
(B) shows phase characteristics. As is clear from FIG. 2A, the peak value of the gain near 1600 Hz, which is the natural frequency of the mechanical system, could be reduced by 9 dB as compared with FIG. 4 described above (point B).

As described above, the movable portion 4 and the movable portion 4
By inserting the vibration damping material 10 between any two parts of the optical system base 10 attached integrally with the
The peak of the gain near 1600 Hz, which is the natural frequency of the mechanical system, can be reduced, and a precision feed unit resistant to disturbance can be realized.

[0019]

As described above, according to the present invention, the vibration damping material is inserted between any two of the components constituting the movable portion of the air slide and the components integrally attached to the movable portion. Therefore, the peak value of the gain near 1600 Hz, which is the natural frequency of the mechanical system, can be reduced, and a precision feed unit resistant to disturbance can be realized.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a loop transfer function in the precision feed unit shown in FIG. 1;

FIG. 3 is a side view of a conventional precision feed unit.

FIG. 4 is a diagram showing a loop transfer function in a conventional precision feed unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base plate 2 Prop 3 Guide 4 Movable part 5 Linear motor coil 6 Linear motor magnetic circuit 7 Scale 8 Scale mount 9 Scale head 10 Damping material 11 Optical base 12 Optical system parts

Claims (4)

[Claims] 1. A precision feed unit driven by an actuator so that an air slide travels along a guide member in a non-contact manner and precisely positions a component mounted on a movable portion of the air slide. A precision feed unit characterized in that a vibration damping material is inserted between any two of a part constituting the part and a part integrally attached to the movable part. 2. The precision feed unit according to claim 1, wherein the position of the air slide is detected by a displacement sensor, and the actuator outputs are feedback-controlled based on the detected output. 3. The vibration damping material has a thickness of several hundred μm.
m or less viscoelastic material,
The precision feed unit according to claim 1. 4. The vibration damping material has a thickness of several hundred μm.
2. The precision feed unit according to claim 1, wherein the precision feed unit is a damping steel plate having a diameter of not more than m.