Title:
FREQUENCY DIFFERENCE DETECTION CIRCUIT AND MEASURING UNIT EMPLOYING IT
Document Type and Number:
Japanese Patent JP3151153
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To obtain a hardness meter utilizing a frequency difference detection circuit in which hardness information can be measured accurately over a wide range from a soft object to a hard object.
SOLUTION: The hardness meter utilizing a frequency difference detection circuit comprises a contact element 5, an oscillator 3, a self-excited oscillation circuit 11 and a gain variation correction circuit 13. The self-excited oscillation circuit 11 feeds back the oscillation information of oscillator 3 to bring about a resonant condition. The gain variation correction circuit 13 is provided in the self-excited oscillation circuit 11. The gain variation correction circuit 13 has central frequency different from that of the self-excited oscillation circuit 11 and increases the gain for the frequency variation.
Inventors:
Sadao Omata
Application Number:
JP23340696A
Publication Date:
April 03, 2001
Filing Date:
September 03, 1996
Export Citation:
Assignee:
Sadao Omata
Axim Co., Ltd.
Axim Co., Ltd.
International Classes:
A61B5/00; A61B5/103; G01L1/10; G01H13/00; G01L9/12; G01N3/40; G01N11/16; G01N29/09; G01P15/097; G01P15/10; (IPC1-7): G01N29/16; A61B5/00
Domestic Patent References:
| JP381641A | ||||
| JP5322731A |
Attorney, Agent or Firm:
Kenji Yoshida (2 outside)
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