Replaceable unit for an image forming device having magnets of varying angular offset for toner level sensing
View Patent ↗A replaceable unit for an electrophotographic image forming device according to one example embodiment includes a housing having a reservoir for storing toner. A rotatable shaft is positioned within the reservoir and has an axis of rotation. A first magnet and a second magnet are connected to the shaft and rotatable around the axis of rotation in response to rotation of the shaft. The first magnet and the second magnet are detectable by a magnetic sensor when the replaceable unit is installed in the image forming device. A polarity of the first magnet is oriented opposite a polarity of the second magnet relative to the shaft. An amount of angular offset between the first magnet and the second magnet varies depending on an amount of toner in the reservoir.
1. A replaceable unit for an electrophotographic image forming device, comprising:
a housing having a reservoir for storing toner;
a rotatable shaft positioned within the reservoir and having an axis of rotation;
a first linkage rotatable with the rotatable shaft around the axis of rotation, the first linkage having a first permanent magnet; and
a second linkage rotatable around the axis of rotation in response to rotation of the rotatable shaft, the second linkage having a second permanent magnet, the second linkage is rotatable independent of the rotatable shaft between a forward rotational stop and a rearward rotational stop such that an amount of angular offset between the first permanent magnet and the second permanent magnet varies depending on a rotational position of the second linkage relative to the forward rotational stop and the rearward rotational stop, the second permanent magnet is spaced angularly relative to the operative rotational direction of the rotatable shaft from the first permanent magnet when the second linkage is at the forward rotational stop and when the second linkage is at the rearward rotational stop.
2. The replaceable unit of claim 1 , wherein the second linkage includes a paddle member leading the first permanent magnet in the operative rotational direction of the rotatable shaft such that the paddle member is positioned closer to a leading end of the first permanent magnet than to a trailing end of the first permanent magnet in the operative rotational direction of the rotatable shaft.
3. The replaceable unit of claim 2 , wherein the second permanent magnet is positioned on the paddle member.
4. The replaceable unit of claim 1 , wherein the second linkage is biased by a spring in the operative rotational direction of the rotatable shaft toward the forward rotational stop.
5. The replaceable unit of claim 1 , wherein the first permanent magnet is axially aligned with the second permanent magnet with respect to the axis of rotation.
6. The replaceable unit of claim 1 , wherein the first permanent magnet is radially aligned with the second permanent magnet with respect to the axis of rotation.
7. The replaceable unit of claim 1 , wherein the first permanent magnet and the second permanent magnet pass near a point on an inner wall of the housing forming the reservoir once per revolution of the rotatable shaft for detection by a magnetic sensor when the replaceable unit is installed in the image forming device.
8. The replaceable unit of claim 1 , wherein the first linkage is fixed to rotate with the rotatable shaft.
9. The replaceable unit of claim 1 , wherein a polarity of the first permanent magnet is oriented opposite a polarity of the second permanent magnet relative to the rotatable shaft.