Claims
- 1. Apparatus for detecting irregularities in the surface of an object, comprising:
- a transducer adapted to be moved over the surface and provide output signals representative of surface irregularities thereof;
- said output signal comprising a first low frequency signal resulting from the varying distance between the transducer and the surface and a second signal of higher frequency than said first signal and representative of said surface irregularities;
- means for processing said output signal and including parallel first and second channels, said first channel conducting said output signal and said second channel including means for delaying said output signal, said processing means further including means for combining the output signal from said first channel and the delayed output signal from said second channel to essentially remove said low frequency signal and enhance said second signal to produce a measuring output signal representative of said surface irregularities.
- 2. Apparatus according to claim 1, wherein said means for delaying comprises at least one analog shift register.
- 3. Apparatus according to claim 1, wherein said means for combining comprises a summation circuit.
- 4. Apparatus according to claim 1, further comprising means for filtering said measuring output signal.
- 5. Apparatus according to claim 1, wherein said means for delaying delays said output signal by a period T.sub.d.
- 6. Apparatus according to claim 5, wherein said period t.sub.d is variable in dependence upon the characteristics of the surface irregularities.
- 7. Apparatus according to claim 1, wherein said means for delaying also inverts said output signal.
- 8. Apparatus according to claim 7, wherein said means for delaying delays said output signal by a period T.sub.d.
- 9. Apparatus according to claim 8, wherein said period t.sub.d is variable in dependence upon the characteristics of the surface irregularities.
- 10. Apparatus for detecting irregularities in the surface of an object, comprising:
- a transducer adapted to be moved over the surface and provide output signals representative of surface irregularities thereof;
- said output signal comprising a first signal having a frequency characteristic of varying lift-off distance between the transducer and the surface and a second signal of higher frequency than said first signal and representative of said surface irregularities;
- means responsive to said output signal for generating a delayed and inverted output signal; and
- means for summing said output signal and said delayed and inverted output signal to essentially cancel said first signal and enhance said second signal representative of surface irregularities.
- 11. Apparatus according to claim 10, wherein said means for generating delays said output signal by a period T.sub.d.
- 12. Apparatus according to claim 11, wherein said period t.sub.d is variable in dependence upon the characteristics of the surface irregularities.
Priority Claims (1)
Number |
Date |
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8206678 |
Nov 1982 |
SEX |
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Parent Case Info
This application is a continuation, of application Ser. No. 621,916, filed June 15, 1984, as PCT SE83/00409 on Nov. 22, 1983 as WO84/02189 on June 7, 1984, now abandoned.
US Referenced Citations (12)
Foreign Referenced Citations (5)
Number |
Date |
Country |
7201970 |
Jun 1975 |
SEX |
75078576 |
May 1977 |
SEX |
76137082 |
May 1982 |
SEX |
652479 |
Mar 1979 |
SUX |
2041535 |
Sep 1980 |
GBX |
Non-Patent Literature Citations (1)
Entry |
D. D. Buss et al., "Transversal Filtering Using Charger-Transfer Devices" in IEEE Journal of Solid-State Circuits, vol. Sc-8, No. 2, Apr. 1973. |
Continuations (1)
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Number |
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Parent |
621916 |
Jun 1984 |
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