Rotation sensor for an injection device
The present disclosure relates to a rotation sensor for an injection device, the rotation sensor comprising: a rotatable element configured for a mechanical engagement with a ratchet mechanism, the rotatable element comprising an outer rim and a hub is configured for transmission of a torque between the outer rim and the hub, at least one sensor attached to the rotatable element and configured to measure at least one of a mechanical force, a mechanical pressure or a mechanical strain at a portion of the rotatable element during a rotation of the rotatable element, a processor connected to the at least one sensor and configured to calculate an angle of rotation of the rotatable element on the basis of a sensor output of the at least one sensor.
1 . A rotation sensor for an injection device, the rotation sensor comprising:
a rotatable element comprising an outer rim and a hub configured for transmission of a torque between the outer rim and the hub, wherein the rotatable element comprises at least one ratchet feature configured to periodically engage with at least one counter ratchet feature when the rotatable element is subject to a rotation relative to the counter ratchet feature;
at least one sensor attached to, and rotationally fixed relative to, the rotatable element, and configured to measure a rotation of the rotatable element as the at least one sensor rotates with the rotatable element relative to the counter ratchet feature while the at least one ratchet feature periodically engages with the at least one counter ratchet feature; and
a processor connected to the at least one sensor and configured to calculate an angle of rotation of the rotatable element based on a sensor output of the at least one sensor.
2 . The rotation sensor according to claim 1 , wherein the at least one sensor is arranged on the outer rim.
3 . The rotation sensor according to claim 1 , wherein the rotatable element comprises at least two spokes and wherein the outer rim and the hub are connected via the at least two spokes.
4 . The rotation sensor according to claim 3 , wherein the at least one sensor is attached to at least one of the at least two spokes.
5 . The rotation sensor according to claim 3 , wherein at least one of the at least two spokes comprises an outer portion connected to the outer rim, an inner portion connected to the hub and a middle portion connecting the outer portion and the inner portion and wherein one of the inner portion, the middle portion, or the outer portion comprises a cross-section that is smaller than a cross-section of another one of the inner portion, the middle portion or the outer portion.
6 . The rotation sensor according to claim 5 , wherein a cross-section of the middle portion is smaller than a cross-section of at least one of the outer portion or the inner portion.
7 . The rotation sensor according to claim 5 , wherein the at least one sensor is arranged on the one of the inner portion, the middle portion, or the outer portion having the cross-section that is smaller than the cross-section of the other one of the inner portion, the middle portion and the outer portion.
8 . The rotation sensor according to claim 3 , wherein at least one of the at least two spokes is configured to elastically deform when a torque is transmitted between the hub and the rim.
9 . The rotation sensor according to claim 1 , wherein the at least one sensor comprises at least one of a quantum tunneling composite QTC, a force-sensing resistor, or a strain gauge integrated into the rotatable element or adhesively attached to a portion of the rotatable element.
10 . The rotation sensor according to claim 1 , wherein at least one of the ratchet feature or the counter ratchet feature comprises a flexible or pivotable arm configured to flex or to pivot relative to the other one of the ratchet feature or the counter ratchet feature to enable a rotation of the ratchet feature past the at least one counter ratchet feature.
11 . The rotation sensor according to claim 1 , wherein the processor is configured to detect a temporal variation of an amplitude of the sensor output.
12 . The rotation sensor according to claim 1 , wherein the rotation sensor is attachable to the injection device such that the rotatable element is rotationally lockable to one of a dial member of the injection device or one of a housing and a trigger of the injection device and is rotatable relative to the other one of the dial member or one of the housing and the trigger via a ratchet mechanism.
13 . The rotation sensor according to claim 1 , wherein the rotatable element is rotatable relative to the counter ratchet feature only along a first sense of rotation and prevented or inhibited to rotate relative to the counter ratchet feature along an opposite second sense of rotation.
14 . The rotation sensor according to claim 1 , wherein the ratchet mechanism enables a rotation of the rotatable element relative to the counter ratchet feature only along a first sense of rotation.
15 . The rotation sensor according to claim 1 , wherein the ratchet mechanism prevents or inhibits a rotation of the rotatable element relative to the counter ratchet feature along a second sense of rotation.
16 . An injection device for setting and expelling of a dose of a medicament, the injection device comprising:
a housing;
a trigger to initiate and/or to control expelling of the dose;
a dial member rotatable relative to the housing for setting of the dose;
a ratchet mechanism; and
a rotation sensor comprising:
a rotatable element mechanically engaged with the ratchet mechanism, the rotatable element comprising an outer rim and a hub configured for transmission of a torque between the outer rim and the hub,
at least one sensor attached to, and rotationally fixed relative to, the rotatable element, and configured to measure a rotation of the rotatable element as the at least one sensor rotates with the rotatable element relative to the housing while engaged with the ratchet mechanism, and
a processor connected to the at least one sensor and configured to calculate an angle of rotation of the rotatable element based on a sensor output of the at least one sensor,
wherein the rotatable element is rotationally locked to one of the dial member and the housing and wherein the rotatable element is rotatable relative to the other one of the dial member and the housing via the ratchet mechanism.
17 . The injection device according to claim 16 , wherein the at least one sensor is arranged on the outer rim.
18 . The injection device according to claim 16 , wherein the rotatable element comprises at least two spokes and wherein the outer rim and the hub are connected via the at least two spokes.
19 . The injection device according to claim 18 , wherein the at least one sensor is attached to at least one of the at least two spokes.
20 . The injection device according to claim 18 , wherein at least one of the at least two spokes comprises an outer portion connected to the outer rim, an inner portion connected to the hub and a middle portion connecting the outer portion and the inner portion and wherein one of the inner portion, the middle portion, or the outer portion comprises a cross-section that is smaller than a cross-section of another one of the inner portion, the middle portion or the outer portion.
21 . The injection device according to claim 20 , wherein a cross-section of the middle portion is smaller than a cross-section of at least one of the outer portion or the inner portion.