Touch signal probe and signal processing apparatus and signal processing method of the same

• US 6,643,944 B2
• Filed: 05/30/2002
• Issued: 11/11/2003
• Est. Priority Date: 05/31/2001
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: Miyazaki, Tomoyuki, Yoda, Yukiji, Kobayashi, Yoshikazu, Nishitsuji, Yutaka, Akagi, Keiji
• Primary Examiner(s): Fulton, Christopher W.
• Application Number:
  US10/158,247
• Publication Number:
  US 20020180470A1
• Time in Patent Office: 530 Days
• Field of Search: 335/58, 335/61
• US Class Current: 33/558
• CPC Class Codes: G01B 7/012 Contact-making feeler heads therefor

Abstract

A touch signal probe comprises a fixed member, a movable member, a bias means, a drive member, a deformation touch signal processing circuit, a contact touch signal processing circuit, and a latch circuit. A stylus is attached to the movable member. The drive member relatively drives reseat position elements respectively placed on the fixed member and the movable member. The bias means restores the movable member to a still position. The deformation touch signal processing circuit generates a deformation touch signal. The contact touch signal processing circuit uses the reseat position elements as make-and-break electric contacts to generate a contact touch signal. The latch circuit inputs coordinate values every instant at which the deformation touch signal is output and stores the coordinate values as the most recent coordinate values for update, and when the contact touch signal is output, outputs the most recent coordinate values as detected coordinate values.

Claims

1. A signal processing apparatus of a touch signal probe used for a machine capable of measuring coordinate values of the touch signal probe, the touch signal probe having a fixed member, a movable member to which a stylus comprising a contact element and a deformation detection element is attached, a fixed member side reseat position element being placed on the fixed member, a movable member side reseat position element being placed on the movable member for coming in contact with the fixed member side reseat position element, and a bias member for allowing displacement of the movable member relative to the fixed member when an external force acts on the stylus and restoring the movable member to a still position by a bias force when the external force acting on the stylus disappears, said signal processing apparatus comprising:

a drive circuit for outputting a drive signal for causing the movable member side reseat position element to make a relative move to the fixed member side reseat position element;

a deformation touch signal processing circuit for generating a deformation touch signal from the deformation detection element;

a contact touch signal processing circuit using the fixed member side and movable member side reseat position elements as make-and-break electric contacts to generate a contact touch signal from the make-and-break electric contacts; and

a latch circuit for inputting the coordinate values every instant at which the deformation touch signal is output and storing the coordinate values as the most recent coordinate values for update and when the contact touch signal is output, outputting the most recent coordinate values as detected coordinate values.

2. The signal processing apparatus of the touch signal probe as claimed in claim 1, wherein the deformation touch signal processing circuit includes a high-pass filter circuit and a low-pass filter circuit.

3. The signal processing apparatus of the touch signal probe as claimed in claim 2, wherein the high-pass filter circuit has a cutoff frequency ranging from 3 kHz to 10 kHz.

4. The signal processing apparatus of the touch signal probe as claimed in claim 2, wherein the low-pass filter circuit has a cutoff frequency ranging from 50 kHz to 200 kHz.

5. The signal processing apparatus of the touch signal probe as claimed in claim 1, wherein the deformation touch signal processing circuit includes an amplification circuit wherein gain switching is possible.

6. The signal processing apparatus of the touch signal probe as claimed in claim 5, wherein the amplification circuit switches the gain by a gain signal provided from the machine.

7. The signal processing apparatus of the touch signal probe as claimed in claim 1, wherein the deformation touch signal processing circuit includes a comparison circuit.

8. The signal processing apparatus of the touch signal probe as claimed in claim 7, wherein the deformation touch signal processing circuit includes a monostable multivibrator started by output of the comparison circuit and converts a high-frequency signal output from the deformation detection element by the monostable multivibrator into a digital low-frequency signal.

9. The signal processing apparatus of the touch signal probe as claimed in claim 7, wherein the comparison circuit switches a threshold level by a threshold level signal provided from the machine.

10. The signal processing apparatus of the touch signal probe as claimed in claim 1, wherein the drive circuit causes the movable member side reseat position element to make a relative move to the fixed member side reseat position element on the basis of a reseat position correcting signal provided from the machine.

11. A touch signal probe comprising:

a fixed member;

a movable member to which a stylus comprising a contact element and a deformation detection element is attached;

a fixed member side reseat position element being placed on the fixed member;

a movable member side reseat position element being placed on the movable member for coming in contact with the fixed member side reseat position element;

A bias member for allowing displacement of the movable member relative to the fixed member when an external force acts on the stylus and restoring the movable member to a still position by a bias force when the external force acting on the stylus disappears;

a drive member for causing the movable member side reseat position element to make a relative move to the fixed member side reseat position element;

a deformation touch signal processing circuit for generating a deformation touch signal from the deformation detection element;

a contact touch signal processing circuit using the fixed member side and movable member side reseat position elements as make-and-break electric contacts to generate a contact touch signal from the make-and-break electric contacts; and

a signal processing unit having a latch circuit for inputting coordinate values of the touch signal probe every instant at which the deformation touch signal is output and storing the coordinate values as the most recent coordinate values for update and when the contact touch signal is output, outputting the most recent coordinate values as detected coordinate values.

12. The touch signal probe as claimed in claim 11, wherein the movable member side reseat position element comes in contact with the fixed member side reseat position element at each contact point with two at three apart places from each other.

13. The touch signal probe as claimed in claim 12, wherein the drive member is a contact point displacement member for changing the contact point on the fixed member side and the contact point on the movable member side relatively at least a predetermined distance.

14. The touch signal probe as claimed in claim 12, wherein the drive member causes relative vibration only for a given time while holding contact between the contact points on the fixed member side and the movable member side after the external force acting on the movable member disappears.

15. The touch signal probe as claimed in claim 11, wherein a diameter of the bias area containing a point biasing the movable member by the bias member is 20% or less of a diameter of a kinematic circle containing the contact points on the circumference with the axis of the stylus as the center and is roughly equal to or more than a pinpoint.

16. The touch signal probe as claimed in claim 15, wherein a center of the bias area roughly matches a barycentric position of the movable member.

17. The touch signal probe as claimed in claim 15, wherein a center of the bias area roughly matches a center of the kinematic circle.

18. The touch signal probe as claimed in claim 15, wherein the bias member includes a helical spring and a length of the helical spring is about one time or more and 2.5 times or less a diameter of the helical spring.

19. A signal processing method of a touch signal probe for use with a machine capable of measuring coordinate values of said touch signal probe, the touch signal probe having a fixed member, a movable member to which a stylus comprising a contact element and a deformation detection element is attached, a fixed member side reseat position element being placed on the fixed member, and a movable member side reseat position element being placed on the movable member for coming in contact with the fixed member side reseat position element, a drive member for causing the movable member side reseat position element to make a relative move to the fixed member side reseat position element, an bias member for allowing displacement of the movable member relative to the fixed member when an external force acts on the stylus and restoring the movable member to a still position by a bias force when the external force acting on the stylus disappears, a deformation touch signal processing circuit including an operation circuit for enabling an operation condition to be switched, for generating a deformation touch signal from the deformation detection element, and a contact touch signal processing circuit using the fixed member side and movable member side reseat position elements as make-and-break electric contacts to generate a contact touch signal from the make-and-break electric contacts, said signal processing method comprising:

positioning the touch signal probe before a measurement point of a work;

driving the drive member for making a reseat position correction;

switching the operation condition of the operational circuit for enhancing sensitivity;

feeding the touch signal probe into the measurement point for measuring;

when the deformation touch signal is input, inputting the coordinate values and storing the coordinate values as the most recent coordinate values for update;

when the contact touch signal is input, outputting the most recent coordinate values as detected coordinate values; and

switching the operation condition of the operational circuit for lowering the sensitivity.