Object position sensor using magnetic effect device
AssigneeCanon Kabushiki Kaisha
InventorNobuhiro Takeda
Life of this patent
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Abstract
A position sensor comprising a scale structure 7 having magnetic poles positioned with a predetermined distance alternatively magnetized poles one to another, at least two magnetic sensing elements M11 and M12 having a resistance variable in response to the magnetic field of the scale structure, and external connecting terminals 14, 15, and 16 are connected for applying a voltage and for producing an output signal from the intermediate terminal. The terminals each is formed to have a width in the direction in parallel to the magnetic field being 2m times the pole width (m=1, 2, 3, . . . ) of the scale structure, thereby the terminals being prevented from the effect of resistance variation by the magnetic field to provide a position information with an increased accuracy.
Claims8
A magnetic resistance effect device comprising:
- a plurality of magnetic sensing groups, each of said magnetic sensing groups including at least two magnetic sensing elements, each of whose resistance value is variable in response to a magnetic field generated in a scale structure including a plurality of magnetic poles of alternating polarity and equal width arranged serially in the longitudinal direction of the scale structure, said at least two magnetic sensing elements arranged spaced apart from each other by substantially the same distance as a width of the magnetic poles, each of said sensing groups arranged spaced apart from each other by substantially an integer multiple of a half of the width of the magnetic poles, wherein a voltage is applied to both outermost said magnetic sensing elements of a pair of consecutive magnetic sensing groups and an output is obtained from a connection between intermediate magnetic sensing elements of said pair of sensing groups;
- and
- each sensing group including a wiring group comprising a plurality of wiring leads for applying said voltage and obtaining said output, each wiring group including among said wiring leads, leads arranged in the direction orthogonal to the longitudinal direction of the scale structure including a first lead associated with the outermost sensing element of the sensing group and a second lead associated with the intermediate sensing element of the sensing group and spaced from the first lead by an integer multiple of the width of the magnetic poles.
A position sensing apparatus comprising:
- (a) a scale structure including a plurality of magnetic poles of alternating polarity and equal width arranged serially in the longitudinal direction of the scale structure;
- (b) a plurality of magnetic sensing groups constituted by sensing element groups having at least two sensing elements spaced apart from each other by essentially the same width as the width of the magnetic poles, and each of said magnetic sensing groups arranged spaced apart from each other by the distance of an integer multiple of a half of the width of said magnetic poles, and a voltage being applied to both outermost said magnetic sensing elements of a pair of consecutive sensing groups, and an output being obtained from a connection between intermediate magnetic sensing elements of a pair of consecutive magnetic sensing groups;
- wherein each said sensing group including a wiring group including wiring leads necessary for applying said voltage and obtaining said output, each wiring group including, among said wiring leads, leads arranged in the direction orthogonal to the longitudinal direction of the scale structure including a first lead associated with the outermost sensing element of the sensing group and a second lead associated with the intermediate sensing element of the sensing group and spaced from the first lead by an integer multiple of the width of the magnetic poles.
Dependencies are inferred from the claim text.