Minebea Mitsumi Inc.

Hiroki Negishi

Yasuo Osada

Katsunori Saito

Norikazu Sato

An absolute encoder includes a spindle gear fixed to a motor shaft, a permanent magnet provided on the spindle gear, and a first driven gear having a center axis perpendicular to a center axis of a worm gear portion, and engaging the worm gear portion. The absolute encoder includes a second driving gear provided coaxially with the first driven gear and rotating according to a rotation of the first driven gear, and a second driven gear having a center axis perpendicular to the center axis of the first driven gear, and engaging the second driven gear. The spindle gear includes a magnet holder which is fit onto a tip end of the motor shaft, coaxially with the motor shaft, and a resin gear portion provided with the worm gear portion on an outer side in a radial direction.

Absolute encoder

An absolute encoder preferable in being made compact is provided. The absolute encoder includes a worm gear () that rotates in accordance with rotation of a main spindle, and a worm wheel () of which a central axis is perpendicular to a central axis of the worm gear (), the worm wheel engaging with the worm gear (). The worm gear () is formed using a first material, and the worm wheel () is formed using a second material different from the first material.

An absolute encoder preferable in being made compact is provided. The absolute encoder includes a first drive gear, a first permanent magnet, a first angle sensor, and a first driven gear of a central axis that is perpendicular to a central axis of the first drive gear, the first driven gear engaging with the first drive gear. The absolute encoder includes a second drive gear coaxially provided with the first driven gear, the second drive gear being configured to rotate in accordance with rotation of the first driven gear. The absolute encoder includes a second driven gear of which a central axis is perpendicular to the central axis of the first driven gear, the second driven gear engaging with the second drive gear. The absolute encoder includes a second permanent magnet provided on a top end side of the second driven gear. The absolute encoder includes a second angle sensor configured to detect a rotation angle of the second driven gear, in accordance with a change in magnetic flux generated from the second permanent magnet. A reduction ratio between the first drive gear (worm gear ()) and the first driven gear (worm wheel ()) is set to a value for mitigating an effect of backlash between the first drive gear and the first driven gear, the backlash resulting in an error in the rotation angle of the second driven gear.

Reduction mechanism and absolute encoder

An absolute encoder suitable for size reduction is provided. An absolute encoder includes: a first driving gear configured to rotate according to rotation of a spindle; a first driven gear having a center axis perpendicular to a center axis of the first driving gear and configured to engage with the first driving gear; and a second driving gear provided coaxially with the first driven gear and configured to rotate according to rotation of the first driven gear. The absolute encoder includes a permanent magnet () provided on a layshaft gear (A) having a center axis perpendicular to the center axis of the first driven gear and where a worm wheel portion () is formed to engage with the second driven gear; and a resin sheet (A) provided on the layshaft gear (A) to prevent the permanent magnet () from coming out from the layshaft gear (A) in the axial direction.

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Tokyo, Japan

Hiroki Negishi