Load support mechanism
To realize a mechanism that can support an article at a desired position in such a way as to be able to move the article, with a thin, simple configuration. A load support mechanism 1 includes a fixed support section 2 , which includes a fixed cam 8 ; a movable support section 3 , which receives a load and can move vertically; a horizontal cam groove 13 , which is provided in the movable support section; a cam follower member 15 , which can move horizontally along the cam groove; a first spring 4 , which is mounted between the fixed support section and the movable support section to support a load; and a second spring 18 , which pushes the cam follower member horizontally and presses the cam follower member against a fixed cam surface 9 of the fixed cam. A reaction force of the fixed cam against the cam follower contains a vertical component depending on a height position of the movable support section, and the vertical component assists or reduces the spring's force to push up the load. A cam shape of the fixed cam surface is provided in such a way that the load acting around the cam follower, the spring forces of the first and second springs, and the reaction force applied from the fixed cam are balanced against each other.
1. A load support mechanism comprising:
a fixed support section;
a movable support section that can move in a predetermined direction relative to the fixed support section within a predetermined range and is used to receive a load;
a fixed cam that is provided in the fixed support section and includes a fixed cam surface;
a cam groove that is provided in the movable support section, includes a first and a second movable cam surface that face each other, and extends in a direction that crosses a movement direction of the movable support section;
a cam follower that can move in the cam groove along the cam groove while being in contact with the first or second movable cam surface;
a first spring that is mounted between the fixed support section and the movable support section to support the load; and
a second spring that presses the cam follower against the fixed cam surface,
wherein a reaction force of the fixed cam surface against the cam follower contains a first-direction component, which is generated at a position thereof in the predetermined range in which the movable support section can move and which is applied in the movement direction of the movable support section, and a second-direction component which is perpendicular to at least the movement direction of the movable support section, and
the fixed cam surface has a cam shape by which a load acting around the cam follower, a biasing force of the first spring, the reaction force of the fixed cam surface against the cam follower, and a biasing force of the second spring are balanced in the predetermined range in which the movable support section can move.
2. The load support mechanism according to claim 1 , wherein the fixed cam surface includes an equilibrium region in which forces acting around the cam follower are balanced, and a non-equilibrium region which follows the equilibrium region and in which the forces acting around the cam follower are not balanced.
3. The load support mechanism according to claim 1 , wherein the fixed support section includes outer frame portions on both sides of the movement direction of the movable support section, and both side portions of the movable support section are guided by the outer frame portions in the movement direction.
4. The load support mechanism according to claim 1 , wherein:
the movable support section includes a support member that extends in a direction perpendicular to the movement direction thereof;
the cam groove is provided on the support member; and
the second spring is a compression coil spring that is fitted onto or into the support member to press the cam follower in a direction in which the support member extends.
5. The load support mechanism according to claim 4 , wherein the cam groove extends from around one end of the support member to an opposite side, and the second spring presses the cam follower toward the one end of the support member.
6. The load support mechanism according to claim 5 , wherein:
the cam follower includes a first cam follower member, which passes through the cam groove in a front-back direction of the support member, and a pair of front and rear second cam follower members, which are provided at front and rear ends of the first cam follower member protruding from the cam groove; and
the fixed cam includes a pair of front and rear fixed cam members with which each of the second cam follower members comes in contact.
7. The load support mechanism according to claim 1 , wherein the first and second springs are disposed in such a way as to at least partially overlap with each other when viewed in a direction perpendicular to the movement direction of the movable support section in a planar fashion.