Electronic device
Provided is an electronic device including a rotary power generation device using an electret, which is capable of preventing a spiral spring from being wound up or fully extended. The electronic device includes a power generation mechanism including: first rotary member, which is supported in a freely rotatable manner, and has a center of gravity shifted from a rotation center; second rotary member supported in a freely rotatable manner; an elastic member configured to elastically connect the first rotary member and the second rotary member to each other for rotary motions thereof; a stationary member arranged so as to be opposed to the second rotary member; and an electret film formed on a surface of any one of the second rotary member and the stationary member.
1. An electronic device, comprising a power generation mechanism comprising:
at least one first rotary member, which is supported in a freely rotatable manner, and has a center of gravity shifted from a rotation center;
at least one second rotary member supported in a freely rotatable manner;
an elastic member configured to elastically connect the first rotary member and the second rotary member to each other for rotary motions thereof;
a stationary member arranged so as to be opposed to the second rotary member; and
an electret film formed on a surface of any one of the second rotary member and the stationary member.
2. The electronic device according to claim 1 , wherein a value of a moment of inertia of the first rotary member and a value of a moment of inertia of the second rotary member are different from each other.
3. The electronic device according to claim 2 , wherein the value of the moment of inertia of the first rotary member is larger than the value of the moment of inertia of the second rotary member.
4. The electronic device according to claim 1 , wherein, when the elastic member is in a relaxed state, the following expression is satisfied:
0°<θ<180°,
where θ represents an angle formed between a direction of the center of gravity of the first rotary member as viewed from the rotation center and a direction of a center of gravity of the second rotary member as viewed from the rotation center.
5. The electronic device according to claim 1 , wherein the electret film is formed on the surface of the second rotary member.
6. The electronic device according to claim 1 , wherein the second rotary member has a center of gravity shifted from the rotation center.
7. The electronic device according to claim 1 , further comprising:
an electret film formed on a surface of the first rotary member; and
an additional stationary member arranged so as to be opposed to the first rotary member.
8. The electronic device according to claim 1 , comprising a plurality of the second rotary members, a plurality of the stationary members, and a plurality of the elastic members,
wherein the plurality of second rotary members are elastically connected to each other for rotary motions thereof by a corresponding one of the plurality of elastic members.
9. The electronic device according to claim 1 , further comprising a restriction portion configured to restrict extension of the elastic member to a radially configured outer side.
10. The electronic device according to claim 1 ,
wherein the second rotary member has a through hole formed therein at a rotation center portion thereof, and
wherein the elastic member is received on an inner peripheral surface side of the through hole.