Patent EP0240020A2 successfully refreshed from Google Patents.
EP0240020A2
Expired / Lapsed
EP
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A capacitance type transducer for measuring positions
Assignee: Mitutoyo Corp
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Filing: 1987-04-02
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Granted: —
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Expires: 2007-04-02
Abstract
Abstract Transducers for measuring the amount of relative displacement between the two scales by means of capacitive coupling between a first scale and a second scale which are used in calipers or the like and which are displaced relatively to each other. Transmitting electrodes consisting of a group of a number of electrodes are provided on the first scale, and the transmitting electrodes are each provided with A.C. signals having different phases. Receiving electrodes are provided on the second scale at positions near the aforesaid transmitting electrodes, and different capacity values appear between both groups of electrodes depending upon the relative displacement positions of the two scales. Consequently, the relative positions of both scales can be found by obtaining the A.C. signals of the receiving electrodes. The receiving electrodes consist of a number of electrodes with an equally spaced pitch, obtained by dividing the transmitting wavelength pitch of the transmitting electrodes by a predetermined integer. As a result, it is possible to obtain a measuring precision equal to a fraction of the number of transmitting electrodes within the aforesaid group of transmitting electrodes of the receiving electrode pitch.
Inventors
- 👤 Ingvar Andermo
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 17:01
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/22; H03M1/24; H03M1/28; G; G01; G01B; G01B7/00; G01B7/003; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/24; G01D5/241; G01D5/2412; G01D5/2415
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
164 words
(1) A capacitance type transducer for measuring positions characterized by the fact that it has a first scale and a second scale which are positioned adjacent to each other in a manner so that they can be displaced relatively to each other, both scales are provided with either transmitting electrodes or receiving electrodes, both of which consist of groups of electrodes positioned along the direction in which the scales are relatively displaced and are coupled capacitively with each other, the aforesaid transmitting electrodes form a group of transmitting electrodes to which a number of A.C. signals with different phases are supplied, the aforesaid receiving electrodes consist of a number of electrodes with an equally spaced pitch in which the transmitting wavelength pitch of the aforesaid group of transmitting electrodes is divided by a predetermined integer, and a scale precision amounting to a fraction of the number of transmitting electrodes within the aforesaid group of transmitting electrodes of the aforesaid receiving electrode pitch is possible.
Claim 2
Dependent Claim
65 words
(2) A capacitance type transducer for measuring positions characterized by the fact that, in the transducer described in Claim (1), the receiving electrodes consist of a number of electrodes with an equally spaced pitch in which the transmitting electrode pitch of the aforesaid group of transmitting electrodes is divided by an integer less than the number of transmitting electrodes within the group of transmitting electrodes.
Claim 3
Dependent Claim
33 words
(3) A capacitance type transducer for measuring positions characterized by the fact that, in either one of the transducers described in Claims (1) and (2), the transmitting electrodes have an unequally spaced pitch.
Claim 4
Dependent Claim
78 words
(4) A capacitance type transducer for measuring positions characterized by the fact that, in the transducer described in Claim (1), the sequence of the phases of the A.C. signals supplied to the transmitting electrodes is determined as follows: i.e., when the receiving electrode pitch is divided by the number of transmitting electrodes, A.C. signals having phases in a sequence corresponding to the divided positions of the aforesaid receiving electrode pitch are supplied to each of the transmitting electrodes.
Claim 5
Dependent Claim
350 words
(5) A capacitance type transducer for measuring positions characterized by the fact that it has a first scale and a second scale which are positioned adjacent to each other in a manner so that they can be displaced relatively to each other, the first scale is provided with first transmitting electrodes consisting of a group of electrodes arranged in the direction of relative displacement and a first receiving electrode which is provided in parallel with, but electrically isolated from, these first transmitting electrodes, the aforesaid second scale is provided with second receiving electrodes which consist of a group of electrodes which are arranged in the direction of relative displacement so as to be coupled capacitively with the aforesaid first transmitting electrodes, and second transmitting electrodes which consist of a group of electrodes which are arranged in the direction of relative displacement so as to be coupled capacitively with the aforesaid first receiving electrode, the corresponding electrodes in the aforesaid second receiving electrodes and second transmitting electrodes are each electrically coupled with each other conductively by coupling electrodes, a number of A.C. signals with different phases are supplied to the aforesaid first transmitting electrodes, the aforesaid second receiving electrodes consist of a number of electrodes with an equally spaced pitch in which the transmitting wavelength pitch Wt1 of the aforesaid group of first transmitting electrodes is divided by a predetermined integer, and the A.C. signals with different phases supplied to the aforesaid first transmitting electrodes are transmitted to the second scale side while still retaining the data about the capacity values present between the first transmitting electrodes and the second receiving electrodes, these signals are then conducted electrically by the coupling electrodes to the second transmitting electrodes of the second scale, they are then returned to the first scale side by the capacitive coupling between the second transmitting electrodes and the first receiving electrode, and it is possible to measure the amount of relative displacement with a scale precision of a fraction of the number of transmitting electrodes within the aforesaid group of transmitting of the aforesaid second receiving electrode pitch.
Claim 6
Dependent Claim
69 words
(6) A capacitance type transducer for measuring positions characterized by the fact that, in the transducer described in Claim (5), the second receiving electrodes consist of a number of electrodes with an equally spaced pitch in which the transmitting electrode pitch of the aforesaid group of first transmitting electrodes is divided by an integer less than the number of first transmitting electrodes within the group of first transmitting electrodes.
Claim 7
Dependent Claim
34 words
(7) A capacitance type transducer for measuring positions characterized by the fact that, in either one of the transducers described in Claims (5) and (6), the first transmitting electrodes have an unequally spaced pitch.
Claim 8
Dependent Claim
83 words
(8) A capacitance type transducer for measuring positions characterized by the fact that, in the transducer described in Claim (5), the sequence of the phases of the A.C. signals supplied to the first transmitting electrodes is determined as follows: i.e., when the second receiving electrode pitch is divided by the number of first transmitting electrodes, A.C. signals having phases in a sequence corresponding to the divided positions of the aforesaid second receiving electrode pitch are supplied to each of the first transmitting electrodes.
Claim 9
Dependent Claim
40 words
(9) A capacitance type transducer for measuring positions characterized by the fact that, in the transducer described in Claim (5), the first scale and the second scale are used as either the regular scale or the vernier scale of calipers.
References Cited (Backward Citations)
No citation records indexed.
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