Touch signal probe

• US 6,360,176 B1
• Filed: 04/13/1999
• Issued: 03/19/2002
• Est. Priority Date: 04/14/1998
• Status: Expired due to Fees

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: Ishikawa, Nobuhiro, Nishioki, Nobuhisa
• Primary Examiner(s): Hoff, Marc S.
• Assistant Examiner(s): TSAI, CAROL S W
• Application Number:
  US09/290,610
• Time in Patent Office: 1,071 Days
• Field of Search: 702/33-36, 702/39, 702/54, 702/56, 702/113, 702/115, 702/150-153, 702/167, 702/168, 702/183, 702/184, 700/160, 700/195, 700/275, 700/280, 335/03, 335/04, 335/56, 335/58, 335/59, 335/61, 736/51, 736/49, 736/58, 736/34, 736/62, 735/79
• US Class Current: 702/56
• CPC Class Codes: G01B 7/002 Constructional details of contacts for gauges actuating one or more contacts G01B7/016 takes precedence
• CPC Class Codes: G01B 7/012 Contact-making feeler heads therefor

Abstract

A vibration change is detected by a touch signal probe having a vibrator (16) composed of a stylus support (10) and a stylus (13) attached thereto, and a vibrating/detecting means (12) provided to the stylus support (10) for applying vibration to the vibrator (16) and detecting a vibration condition changing when the stylus (13) touches a workpiece. The vibrator (16) is vibrated at a frequency equivalent to secondary intrinsic frequency (w2) to make resonance and the vibration change is detected by superposing a vibration component of primary intrinsic frequency (w1). Though the vibration at the secondary intrinsic frequency (w2) has high Q value, response amplitude is small. Accordingly, the vibration change is amplified by superposing the vibration component of the primary intrinsic frequency (w1).

Claims

1. A touch signal probe, comprising:

a stylus support having a center defining an origin of mutually orthogonal X- and Y-axes;

a vibrator attached to the stylus support and having at least one stylus extending along at least one of the X-axis and Y-axis; and

a vibration generator/detector formed on the stylus support for vibrating the vibrator at a predetermined frequency and for detecting a change in the vibration of the vibrator caused when the stylus contacts a workpiece,

wherein the predetermined frequency is one of a primary intrinsic frequency ω

1 and a secondary intrinsic frequency ω

2 (ω

2≠

ω

1) of the vibrator, whereby the change in the vibration of the vibrator is amplified by occurrence and superposition of a vibration component of the other of the primary intrinsic frequency ω

1 and the secondary intrinsic frequency ω

2 to the vibration of the vibrator when the stylus contacts the workpiece.

2. The touch signal probe according to claim 1, further comprising a beat signal component sampling element for detecting a beat signal generated by said superposition.

3. The touch signal probe according to claim 1, wherein the at least one stylus includes a first pair of styluses extending along the X-axis and symmetrically disposed with respect to the origin and a second pair of styluses extending along the Y-axis and symmetrically disposed with respect to the origin.

4. The touch signal probe according to claim 1, wherein the at least one stylus includes a stylus member and a balance member provided on opposite sides of the stylus support along said at least one of the X-axis and Y-axis, the balance member being configured to be dynamically equivalent to the stylus member.

5. A touch signal probe, comprising:

a stylus support;

a vibrator including a plurality of styluses each projecting from the stylus support and having a contact portion at a distal end thereof for contacting a workpiece;

a vibration generator disposed on the stylus support for vibrating the vibrator at a predetermined frequency approximately coincident with an intrinsic frequency of the vibrator;

a plurality of vibration detectors each disposed on the stylus support corresponding to one of the plurality of styluses for generating a contact detection signal upon detecting a change in the vibration of the vibrator caused when the contact portion or portions of at least one of the plurality of styluses touches the workpiece; and

a control element for arithmetically processing the contact detection signals generated by the vibration detectors to generate a contact trigger signal,

wherein the control element separately processes, without combining, the contact detection signals so that the detection of the change in the vibration of the vibrator is not affected by the contact detection signal or signals generated by the stylus or styluses not touching the workpiece and a direction in which the contact portion or portions touches the workpiece.

7. The touch signal probe according to claim 5, wherein the plurality of vibration detectors and the vibration generator are disposed on opposite sides of the stylus support, and the plurality of styluses project from regions of the stylus support between the opposite sides.

8. The touch signal probe according to claim 5, wherein said predetermined frequency is one of a primary intrinsic frequency ω

1 and a secondary intrinsic frequency ω

2 (ω

2≠

ω

1) of the vibrator, whereby the change in the vibration of the vibrator is amplified by superposition of a vibration component of the other of the primary intrinsic frequency ω

1 and the secondary intrinsic frequency ω

2 to the vibration of the vibrator when the vibrator contacts the workpiece.

6. A touch signal probe, comprising:

a stylus support;

a vibrator including a plurality of styluses each projecting from the stylus support and having a contact portion at a distal end thereof for contacting a workpiece;

a vibration generator disposed on the stylus support for vibrating the vibrator at a frequency approximately coincident with an intrinsic frequency of the vibrator;

a plurality of vibration detectors each disposed on the stylus support corresponding to one of the plurality of styluses for generating a contact detection signal upon detecting a change in the vibration of the vibrator caused when the contact portion or portions of at least one of the plurality of styluses touches the workpiece; and

a control element for arithmetically processing the contact detection signals generated by the vibration detectors to generate a contact trigger signal;

wherein the control element separately processes, without combining, the contact detection signals; and

wherein the control element generates for each of the contact detection signals an intermediate contact signal, and selects one of the intermediate contact signals which first satisfies a predetermined condition as the contact trigger signal, whereby the detection of the change in the vibration of the vibrator is not affected by the contact detection signal or signals generated by the stylus or styluses not touching the workpiece and a direction in which the contact portion or portions touches the workpiece.

9. A touch signal probe, comprising:

a vibrator including a stylus support and at least one stylus projecting from the stylus support along one of a X-axis and a Y-axis, said vibrator having a first intrinsic frequency associated with a first resonance mode in which a maximum and a minimum of vibrations of the vibrator in the X-axis are substantially temporally coincident with a maximum and a minimum of vibrations of the vibrator in the Y-axis, respectively, and a second intrinsic frequency associated with a second resonance mode in which the maximum and minimum of the vibrations of the vibrator in the X-axis are substantially coincident with the minimum and maximum of the vibrations of the vibrator in the Y-axis, respectively;

a vibration generator formed on the stylus support for vibrating the vibrator at one of the first and second intrinsic frequencies; and

a vibration detector for detecting a change in the vibration of the vibrator caused when the stylus contacts a workpiece.

10. The touch signal probe of claim 9, further comprising a beat signal component sampling element tuned to detect a beat signal generated when the stylus contacts the workpiece, said beat signal being of a frequency which is substantially equal to a difference between the first and second intrinsic frequencies.

11. The touch signal probe of claim 9, wherein the vibrator is configured to have a first vibration amplitude associated with the first resonance mode substantially equal to a second vibration amplitude associated with the second resonance mode.

12. The touch signal probe of claim 9, further comprising

a detecting circuit coupled to the vibration detector for receiving a detection signal indicative of a status of the vibration of the vibrator; and

a vibrating circuit coupled to the vibration generator for supplying a driving signal thereto to vibrate the vibrator, said vibrating circuit including;

an intrinsic frequency sampling circuit coupled to said detecting circuit for receiving the detection signal and extracting said one of the first and second intrinsic frequencies therefrom; and

and a driving circuit coupled to said intrinsic frequency sampling circuit and generating the driving signal based on the extracted one of the first and second intrinsic frequencies.

13. The touch signal probe of claim 9, wherein the at least one stylus includes a first pair of symmetrical styluses extending in opposite directions along said one of the X-axis and the Y-axis.

14. The touch signal probe of claim 13, wherein the at least one stylus further includes a second pair of symmetrical styluses extending in opposite directions along the other of the X-axis and the Y-axis.

15. The touch signal probe of claim 9, wherein the at least one stylus includes a stylus member and a balance member provided on opposite sides of the stylus support along said one of the X-axis and Y-axis, the balance member being configured to be dynamically equivalent to the stylus member and projecting from the stylus support for a length substantially shorter than that of the stylus member.

16. The touch signal probe of claim 15, wherein the at least one stylus further includes another pair of balance members provided on opposite sides of the stylus support along the other of the X-axis and Y-axis, the another pair of balance members being configured to be dynamically equivalent to each other and projecting from the stylus support for a length substantially shorter than that of the stylus member.

17. The touch signal probe of claim 9, wherein the vibration detector and generator are disposed on opposite sides of the stylus support, and the at least one stylus project from a region of the stylus support positioned between said opposite sides.

18. The touch signal probe of claim 9, wherein the at least one stylus includes a plurality of styluses and the vibration detector comprises a plurality of detecting electrodes each positioned corresponding one of the plurality of styluses for detecting a change in the vibration of thereof, said detecting electrodes are not electrically commonly connected.

19. A method of sensoring a workpiece, comprising the steps of:

providing a vibrator including a stylus support and at least one stylus projecting from the stylus support along one of a X-axis and a Y-axis, said vibrator having a first intrinsic frequency associated with a first resonance mode in which a maximum and a minimum of vibrations of the vibrator in the X-axis are substantially temporally coincident with a maximum and a minimum of vibrations of the vibrator in the Y-axis, respectively, and a second intrinsic frequency associated with a second resonance mode in which the maximum and minimum of the vibrations of the vibrator in the X-axis are substantially coincident with the minimum and maximum of the vibrations of the vibrator in the Y-axis, respectively;

vibrating the vibrator at one of the first and second intrinsic frequencies; and

detecting a change in the vibration of the vibrator caused when the stylus contacts the workpiece.