Magneto resistive sensor for detecting movement of a rotating body

Claim 1

A rotation detecting means for a rotating body comprising: a rotating body whose rotation state is to be detected; a magnetic recording medium which is fixed to said rotating body centering around the center axis of said rotating body, N and S magnetic poles being alternately recorded at a prescribed interval on said recording medium in the rotation direction of said rotating body; at least two groups of magnet-resistive elements disposed at a fixed position opposite to said magnetic recording medium so that their values of resistance may vary with the action of said magnetic poles as recorded on said magnetic recording medium, the widths of said magnet-resistive elements in the rotation direction being made sufficiently smaller than the pitch P of said magnetic poles recorded on said magnetic recording medium, said each group having two branches that comprise one magnet-resistive element, said two branches being disposed at an interval of an odd integer multiple of a minimum interval of P/2 in the rotation direction; and low resistive parts comprising the parts which connect said two branches in series and the parts which connect said two groups in parallel to apply a prescribed voltage to each group so that output signals related to the rotation state of said rotating body may be derived from said connection parts of said two branches; said magnet-resistive elements of each group being disposed in such a manner that the intervals between the groups of magnet-resistive elements are shifted from each other so that output signals have a phase difference.

Claim 9

An apparatus for detecting movement of a moving body comprising: a moving body whose movement state is to be detected; a magnetic recording medium fixed to the moving body, the magnetic recording medium having N and S magnetic poles alternately recorded thereon at a prescribed interval of pitch P in the movement direction of the moving body; at least two groups of magnet-resistive elements disposed at a fixed position opposite to the magnetic recording medium so that the value of resistance of the magnet-resistive elements is variable in accordance with the action of the magnetic poles as recorded on the magnetic recording medium, the widths of the magnet-resistive elements in the movement direction being made sufficiently smaller than the pitch P of the magnetic poles recorded on the magnetic recording medium, each of the groups including two branches wherein each branch has at least one magnet-resistive element and the two branches being spaced from one another in the movement direction by an interval having a predetermined relationship to the Pitch P, the groups being spaced from one another in the movement direction by an interval less than the spacing of the interval between the two branches of each group, and the interval between the groups having a predetermined relationship to the pitch P, the two branches of each group being spaced by an interval of an odd integer multiple of a minimum interval of P/2 in the movement direction; and low resistivity path means for connection with the branches including low resistivity members for connecting the two branches of each group in series, and at least one low resistivity member for connecting the at least two groups in parallel, whereby upon application of a prescribed voltage to the groups, at least one output signal related to the movement state of the moving body may be derived from the low resistivity path means, the low resistivity path means including the low resistivity members enabling a prescribed voltage to be applied to each group so that output signal related to the movement state of the moving body may be derived from the low resistivity members connecting the two branches; the magnet-resistive elements of each group being disposed in such a manner that the intervals between the groups of magnet-resistive elements are shifted from each other so that output signals have a phase difference.

Claim 10

An apparatus for detecting movement of a moving body comprising: a moving body whose movement state is to be detected; a magnetic recording medium fixed to the moving body, the magnetic recording medium having N and S magnetic poles alternately recorded thereon at a prescribed interval of pitch P in the movement direction of the moving body; at least two groups of magnet-resistive elements disposed at a fixed position opposite to the magnetic recording medium so that the value of resistance of the magnet-resistive elements is variable in accordance with the action of the magnetic poles as recorded on the magnetic recording medium, the widths of the magnet-resistive elements in the movement direction being made sufficiently smaller than the pitch P of the magnetic poles recorded on the magnetic recording medium, each of the groups including two branches wherein each branch has at least one magnet-resistive element and the two branches being spaced from one another in the movement direction by an interval having a predetermined relationship to the Pitch P, the groups being spaced from one another in the movement direction by an interval less than the spacing of the interval between the two branches of each group, and the interval between the groups having a predetermined relationship to the pitch P, the two branches of each group being spaced by an interval of an odd integer multiple of a minimum interval of P/2 in the movement direction; and low resistivity path means for connection with the branches including low resistivity members for connecting the two branches of each group in series, and at least one low resistivity member for connecting the at least two groups in parallel, whereby upon application of a prescribed voltage to the groups, at least one output signal related to the movement state of the moving body may be derived from the low resistivity path means, the low resistivity path means including the low resistivity members enabling a prescribed voltage to be applied to each group so that output signal related to the movement state of the moving body may be derived from the low resistivity members connecting the two branches; the magnet-resistive elements of each group being disposed in such a manner that the intervals between the groups of magnet-resistive elements are shifted from each other so that output signals have a phase difference.