Magnetic rotary encoder for detection of incremental angular displacement

A magnetic rotary encoder comprising:

• rotary means attachable to rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce a magnetic field which changes in intensity and direction as said rotary means revolves:
• a magnetic field detector including a magneto-resistor having a stripe-like configuration with width D and longitudinal dimension W and arranged in a plane substantially parallel to the nearest surface of said magnetic medium in the vicinity of said rotary means such as to be spaced relative to said permanent magnet by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20p at its furthest portion, said width D being so selected as not to be in excess of 20p but to be equal or less than p.sec.phi., where .phi. is an angle defined by the nearest surface of said magneto-resistor and said permanent magnet, said magneto-resistor responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotational angle of said rotary means, the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of said magneto-resistor, said magnetic field detector further including high permeable magnetic means provided adjacent and substantially parallel to said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of the rotating conditions of said rotary means.

A magnetic rotary comprising:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded thereon, said magnetic medium having a thickness less than p and producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D, and longitudinal dimension W and arranged in a plane substantially parallel to the nearest surface of said magnetic medium in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than p at its nearest portions and by a spacing equal to or less than 20p at its furthest portion, said width D being so selected as not to be in excess of 20p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnetic medium, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors, said magnetic field detector further including high permeable magnetic means provided adjacent and substantially parallel to said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of rotating conditions of said rotary means.

A magnetic rotary encoder comprising:

• rotary means attachable to a rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D and longitudinal dimension W and arranged in a plane substantially parallel to the nearest surface of said magnetic medium in the vicinity of said rotary means such as to be spaced relative to said magnets by spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20p at its furthest portion, said width D being so selected as not to be in excess of 20p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnets, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to be increment of the rotation angle of said rotary means, the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors, said magnetic field detector further including high permeable magnetic means provided adjacent and substantially parallel to said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signals and producing output signals indicative of the rotating conditions of said rotary means.

A magnetic rotary encoder comprising:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which as a magnetic signal recorded thereon said magnetic medium having a thickness less than p and producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including a magneto-resistor having a stripe-like configuration with width D and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than 20p at its furthest portion said width D being so selected as not to be in excess of 20p but to be equal to or less than p.sec.phi., where .phi. is an angle defined by the nearest surfaces of said magneto-resistor and said magnetic medium, said magneto-resistor responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment to the rotation angle of said rotatary means, and the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of the rotating conditions of said rotary means;
• wherein said magnetic field detector further includes means for slanting the magnetization of said magneto-resistor by an angle of 45.degree. relative to a sense current supplied from said rotary condition detector and flowing through said magneto-resistor.

A magnetic rotary encoder comprising:

• rotary means attachable to rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce a magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including a magneto-resistor having a stripe-like configuration with width D and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said permanent magnetic by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal or less than p.sec.phi., where .phi. is an angle defined by the nearest surface of said magneto-resistor and said permanent magnet, said magneto-resistor responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotational angle of said rotary means, and the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of the rotating conditions of said rotary means;
• wherein said magnetic field detector further includes means for slanting the magnetization of said magneto-resistor by an angle of 45.degree. relative to a sense current supplied from said rotary condition detector and flowing through said magneto-resistor.

A magnetic rotary comprising:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded thereon, said magnetic medium having a thickness less than p and producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D, and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnetic medium, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of rotating conditions of said rotary means;
• wherein the minimum of spacings between adjacent magneto-resistors, S.sub.m satisfy:
• ##EQU15## where .delta.H is a phase deviation where .delta.H is a phase deviation resulting from noises.

A magnetic rotary encoder comprising:

• rotary means attachable to a rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnets by spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnets, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signals and producing output signals indicative of the rotating conditions of said rotary means;
• wherein the minimum of spacings between adjacent magneto-resistors, S.sub.m satisfy:
• ##EQU16## where .delta.H is a phase deviation where .delta.H is a phase deviation resulting from noises.

A magnetic rotary comprising:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded thereon, said magnetic medium having a thickness less than p and producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D, and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnetic medium, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of rotating conditions of said rotary means;
• wherein the spacings between adjacent magneto-resistors satisfy the following:
• ##EQU17## where T is the number of magneto-resistors, h is the number of said analog signals differing in phase, each of the suffixes i and j is a positive integer ranging from 1 to T, S.sub.i,j indicates a spacing between i-th and j-th magneto-resistors, l and k are integers and .delta.H is a phase deviation resulting from noises.

A magnetic rotary encoder comprising:

• rotary means attachable to a rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnets by spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnets, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signals and producing output signals indicative of the rotating conditions of said rotary means;
• wherein the spacings between adjacent magento-resistors satisfy the following:
• ##EQU18## where T is the number of magneto-resistors, h is the number of said analog signals differing in phase, each of the suffixes i and j is a positive integer ranging from 1 to T, S.sub.i,j indicates a spacing between i-th and j-th magneto-resistors, l and k are integers and .delta.H is a phase deviation resulting from noises.

A magnetic rotary comprising:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded thereon, said magnetic medium having a thickness less than p and producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D, and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnetic medium, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of rotating conditions of said rotary means;
• wherein said magnetic field detector further includes means for slanting the magnetization of each said magneto-resistors by an angle of 45.degree. relative to a sense current supplied from said rotary condition detector and flowing through said magneto-resistor.

A magnetic rotary encoder comprising:

• rotary means attachable to a rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnets by spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnets, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signals and producing output signals indicative of the rotating conditions of said rotary means;
• wherein said magnetic field detector further includes means for slanting the magnetization of each of said magneto-resistors by an angle of 45.degree. relative to a sense current supplied from said rotary condition detector and flowing through said magneto-resistor.

A magnetic rotary comprising:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded thereon, said magnetic medium having a thickness less than p and producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D, and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnetic medium, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing output signals indicative of rotating conditions of said rotary means;
• wherein with T standing for the number of said magneto-resistors and h for the number of said analog signals different in phase, said rotary condition detector produces h(h-l) pulse trains at maximum each of which is different in phase, wherein 2.ltoreq.h.ltoreq.T and each of the pulses takes either a leading or trailing edge every time two of the analog signals different in phase take the same value simultaneously.

A magnetic rotary encoder comprising:

• rotary means attachable to a rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including a plurality of magneto-resistors each having a stripe-like configuration with a width D and longitudinal dimension W and arranged in the vicinity of said rotary means such as to be spaced relative to said magnets by spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of one of said magneto-resistors and said magnets, each of said magneto-resistors responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotation angle of said rotary means, and the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of each of said magneto-resistors;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signals and producing output signals indicative of the rotating conditions of said rotary means;
• wherein with T standing for the number of said magneto-resistors and h for the number of said analog signals different in phase, said rotary condition detector produces h(h-l) pulse trains at maximum each of which is different in phase, wherein 2.ltoreq.h.ltoreq.T and each of the pulses takes either a leading or trailing edge every time two of the analog signals different in phase take the same value simultaneously.

A magnetic rotary encoder having a magnetic rotary encoder unit and a housing member for containing said encoder unit wherein said magnetic rotary encoder unit comprises:

• rotary means attachable to a rotatable shaft;
• a magnetic medium endlessly provided on a surface of said rotary means and divided at a pitch p into a plurality of magnetic sections each of which has a magnetic signal recorded thereon, said magnetic medium having a thickness less than p producing an alternating magnetic field as said rotary means revolves;
• a magnetic field detector including at least one magneto-resistor having a stripe-like configuration with a width D and longitudinal dimension W and arranged in a plane substantially parallel to the nearest surface of said magnetic medium in the vicinity of said rotary means such as to be spaced relative to said magnetic medium by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal to or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of said magneto-resistor and said magnetic medium, and said magneto-resistor responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistor change corresponding to the increment of the rotational angle of said rotary means, the boundary dividing each of said magnetic sections being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of said at least one magneto-resistor, said magnetic field detector further including high permeable magnetic means provided adjacent and substantially parallel to said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnetic field detector for receiving said analog signal and producing signals indicative of the rotating conditions of said rotary means, and wherein said housing member has means for magnetically shielding itself from external magnetic fields.

A magnetic rotary encoder having a magnetic rotary encoder unit and a housing member for containing said encoder unit wherein said encoder unit comprises:

• rotary means attachable to rotatable shaft;
• a plurality of permanent magnets arranged on a surface of said rotary means so as to produce a magnetic field which changes in intensity and direction as said rotary means revolves;
• a magnetic field detector including at least one magneto-resistor having a stripe-like configuration with width D and longitudinal dimension W and arranged in a plane substantially parallel to the nearest surface of said magnetic medium in the vicinity of said rotary means such as to be spaced relative to said permanent magnet by a spacing equal to or less than p at its nearest portion and by a spacing equal to or less than 20 p at its furthest portion, said width D being so selected as not to be in excess of 20 p but to be equal or less than p. sec.phi., where .phi. is an angle defined by the nearest surfaces of said magneto-resistor and said permanent magnets, said magneto-resistor responsive to said alternating magnetic field and generating an analog signal representative of its electrical resistance change corresponding to the increment of the rotational angle of said rotary means, the boundary dividing each of said permanent magnets being within approximately 45.degree. from parallel with respect to the direction of said longitudinal dimension of said at least one magneto-resistor, said magnetic field detector further including high permeable magnetic means provided adjacent and substantially parallel to said magneto-resistor;
• and
• a rotary condition detector electrically connected to said magnet field detector for receiving said analog signal and producing signals indicative of the rotating conditions of said rotary means, and wherein said housing member has means for magnetically shielding itself from external magnetic fields.