Absolute position readout apparatus

Patent metadata

Field	Value
Publication number	US-10480963-B2
Application number	US-201715622278-A
Country	US
Kind code	B2
Filing date	Jun 14, 2017
Priority date	Jun 14, 2017
Publication date	Nov 19, 2019
Grant date	Nov 19, 2019

Abstract

An absolute position readout apparatus includes an encoder device and a readout device. The readout device includes multiple first and second magnetic sensing components that correspond to an absolute track of the encoder device, and a third magnetic sensing component and a fourth magnetic sensing components that correspond to an incremental track of the encoder device. The third magnetic sensing component is configured to be spaced apart from the fourth magnetic sensing component by a specific distance, so as to prevent misreading of absolute position information from the first or second magnetic sensing components being at positions corresponding to boundaries between adjacent magnetized regions of the absolute track.

First claim

What is claimed is:

1. An absolute position readout apparatus comprising an encoder device and a readout device that are spaced apart from each other, and said encoder device being movable relative to said readout device in a moving direction;
wherein said encoder device includes an absolute magnetic track and an incremental magnetic track, each of which extends in the moving direction;
wherein said absolute magnetic track has a plurality of absolute-track magnetized regions which form a plurality of absolute-track boundaries thereamong, said absolute-track boundaries being formed equidistantly along the moving direction with a distance between each adjacent two thereof being 2P which defines a width of each of said absolute-track magnetized regions;
wherein said incremental magnetic track has a plurality of first incremental-track magnetized regions with first magnetic polarity and a plurality of second incremental-track magnetized regions with second magnetic polarity which differs from the first magnetic polarity, said first incremental-track magnetized regions and said second incremental-track magnetized regions being arranged alternately and forming a plurality of incremental-track boundaries thereamong, said incremental-track boundaries being formed equidistantly along the moving direction with a distance between each adjacent two thereof being P which defines a width of each of said first and second incremental-track magnetized regions, said absolute-track magnetized regions thereby being wider than said first and second incremental-track magnetized regions;
wherein, for each of said absolute-track boundaries, a closest one of said incremental-track boundaries is spaced apart therefrom by a distance of p in a displacement direction same as or opposite to the moving direction, where 0≤ρ≤2P; and when ρ=0, said absolute-track boundary is aligned with said closest one of said incremental-track boundaries;
wherein said readout device includes:
a group of first magnetic sensing components that correspond to said absolute magnetic track, and that are arranged equidistantly along the moving direction with a distance between each adjacent two thereof being 2P;
a group of second magnetic sensing components that correspond to said absolute magnetic track, wherein said first magnetic sensing components and said second magnetic sensing components are arranged alternately along the moving direction and adjacent ones thereof are spaced apart from each other by a distance of P;
a third magnetic sensing component that corresponds to said incremental magnetic track, and that is spaced apart from a closest one of said first and second magnetic sensing components by a distance of p in the displacement direction; and
a fourth magnetic sensing component that corresponds to said incremental magnetic track, and that is spaced apart from said third magnetic sensing component along the moving direction by a center-to-center distance of (N−0.5)×P, where N is a positive integer; and

wherein, when ρ=0, said third magnetic sensing component is aligned with one of said first magnetic sensing components and said second magnetic sensing components.

2. The absolute position readout apparatus of claim 1 , further comprising a processing unit electrically coupled to said group of first magnetic sensing components, said group of second magnetic sensing components, said third magnetic sensing component and said fourth magnetic sensing component;
said processing unit being configured:
to select, based on a relative positional relationship between said third and fourth magnetic sensing components, and a relative positional relationship between said third magnetic sensing component and said first and second magnetic sensing components, magnetic fields sensed by one of said group of first magnetic sensing components and said group of second magnetic sensing components to perform decoding thereon to obtain absolute position information when one of a first condition, a second condition, a third condition and a fourth condition is satisfied, and
to select magnetic fields sensed by the other one of said group of first magnetic sensing components and said group of second magnetic sensing components to perform decoding thereon to obtain absolute position information when one of a fifth condition, a sixth condition, a seventh condition and an eighth condition is satisfied;

wherein:
the first condition is that said third and fourth magnetic sensing components respectively sense a magnetic field of one of said first incremental-track magnetized regions, and a magnetic field of one of said second incremental-track magnetized regions;
the second condition is that said third and fourth magnetic sensing components respectively sense a magnetic field that falls within a predetermined range corresponding to one of said incremental-track boundaries, and a magnetic field of one of said second incremental-track magnetized regions;
the third condition is that said third and fourth magnetic sensing components each sense a magnetic field of one of said second incremental-track magnetized regions;
the fourth condition is that said third and fourth magnetic sensing components respectively sense a magnetic field of one of said second incremental-track magnetized regions, and a magnetic field that falls within the predetermined range;
the fifth condition is that said third and fourth magnetic sensing components respectively sense a magnetic field of one of said second incremental-track magnetized regions, and a magnetic field of one of said first incremental-track magnetized regions;
the sixth condition is that said third and fourth magnetic sensing components respectively sense a magnetic field that falls within the predetermined range, and a magnetic field of one of said first incremental-track magnetized regions;
the seventh condition is that said third and fourth magnetic sensing components each sense a magnetic field of one of said first incremental-track magnetized regions; and
the eighth condition is that said third and fourth magnetic sensing components respectively sense a magnetic field of one of said first incremental-track magnetized regions, and a magnetic field that falls within the predetermined range.

3. The absolute position readout apparatus of claim 2 , wherein said first magnetic sensing components and said second magnetic sensing components are digital Hall sensors, and said third magnetic sensing component and said fourth magnetic sensing component are analog Hall sensors.

4. The absolute position readout apparatus of claim 1 , wherein the width of each of said absolute-track magnetized regions is twice that of each of said first and second incremental-track magnetized regions.

5. The absolute position readout apparatus of claim 1 , wherein said readout device further includes a fifth magnetic sensing component that is a magnetoresistive sensor that corresponds to said incremental magnetic track, and that is configured to sense movement amount of said first incremental-track magnetized regions and said second incremental-track magnetized regions by magnetic sensing.

6. An absolute position readout apparatus comprising an encoder device and a readout device that are spaced apart from each other, said encoder device being rotatable relative to said readout device in a rotary direction about an axis;
wherein said encoder device includes an absolute magnetic track and an incremental magnetic track which are disposed concentrically and side-by-side and each of which extends in the rotary direction;
wherein said absolute magnetic track has a plurality of absolute-track magnetized regions which form a plurality of absolute-track boundaries thereamong, said absolute-track boundaries being formed equidistantly along the rotary

Assignees

• Hiwin Mikrosystem Corp

Inventors

• Hsiao Heng-Sheng
• Cheng Chi-Yuan
• Sung Cheng-Kuo
• Chin Tsung-Shune
• Wang Sheng-Ching
• Chang Jen-Yuan

Classifications

• G01D5/2458 Primary

  with incremental and absolute tracks on separate encoders · CPC title