Phase shift type linear position detection device
First Claim
1. A phase shift type linear position detecton device comprising:
- at least two primary coils spaced away from each other by a predetermined distance in the linear displacement direction and excited individually by reference AC signals having a predetermined phase difference 360°
/D except 180°
or 360°
;
secondary coils provided in correspondence to said respective primary coils; and
a plurality of core elements of the same configuration fixed to each other with a predetermined pitch distance P in the linear displacement direction and being capable of relative linear displacement with respect to said primary and secondary coils, and each being capable of producing reluctance or permability, depending upon the position relative to said respective primary coils, in respective magnetic circuits of said respective primary coils;
the distance of spacing between said respective primary coils being P(n±
1/D) (where n is any integer) in accordance with the phase difference 360°
/D of the exciting AC signals for said respective primary coils and distance P of one pitch of the arrangement of said core elements, whereby the reluctance of a magnetic circuit of each of said primary coils changes cyclically, with a displacement of one pitch of the arrangement of said core elements constituting one cycle thereof and with the reluctance changes of the magnetic circuits of respective primary coils being out of phase by an amount corresponding to the electrical phase difference between respective exciting AC signals, AC signals induced in said respective secondary coils being summed to produce an output AC signal and this output AC signal having an electrical phase depending upon the relative linear position within the range of one pitch of the arrangement of said core elements.
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Accused Products
Abstract
About a bobbin, there are wound primary coils in axially displaced locations and wound also is a secondary coil. A core is linearly slidably provided in the bobbin. The primary coils are individually excited by AC signals which are out of phase with each other, e.g. a sine wave signal and a cosine wave signal. The secondary coil thereupon produces an output signal resulting from phase shifting the applied sine or cosine wave signal in accordance with a linear position of the core. Accordingly, the linear position can be detected by measuring phase difference between a reference AC signal and the output signal of the secondary coil. Likewise, velocity and acceleration change may be determined using the position change data.
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Citations
19 Claims
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1. A phase shift type linear position detecton device comprising:
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at least two primary coils spaced away from each other by a predetermined distance in the linear displacement direction and excited individually by reference AC signals having a predetermined phase difference 360°
/D except 180°
or 360°
;secondary coils provided in correspondence to said respective primary coils; and a plurality of core elements of the same configuration fixed to each other with a predetermined pitch distance P in the linear displacement direction and being capable of relative linear displacement with respect to said primary and secondary coils, and each being capable of producing reluctance or permability, depending upon the position relative to said respective primary coils, in respective magnetic circuits of said respective primary coils; the distance of spacing between said respective primary coils being P(n±
1/D) (where n is any integer) in accordance with the phase difference 360°
/D of the exciting AC signals for said respective primary coils and distance P of one pitch of the arrangement of said core elements, whereby the reluctance of a magnetic circuit of each of said primary coils changes cyclically, with a displacement of one pitch of the arrangement of said core elements constituting one cycle thereof and with the reluctance changes of the magnetic circuits of respective primary coils being out of phase by an amount corresponding to the electrical phase difference between respective exciting AC signals, AC signals induced in said respective secondary coils being summed to produce an output AC signal and this output AC signal having an electrical phase depending upon the relative linear position within the range of one pitch of the arrangement of said core elements. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A phase shift type linear position detection device comprising:
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a slider having a plurality of spaced cores each approximately P/2 in length, said cores having a pitch distance of P and exhibiting a magnetic permeability characteristic, a set of primary and secondary annular coils disposed in a fixed coaxial relationship to each other, said slider being linearly coaxially displaceable through said coils, said primary coils being individually excited by reference AC signals having a predetermined phase difference 360°
/D except 180°
or 360°
;said secondary coils having a between center spacing of P(n±
1/D) where n is an integer, and being arranged so that for any position of said slider the outputs of said secondary coils are out of phase by an amount equivalent to the phase difference between said primary coil excitation signals,said secondary coils being connected to produce an output AC signal having an electrical phase indicative of the relative linear position of said slider within the range of one pitch of said cores.
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Specification