Balanced moment lift system and method
View Patent ↗A lift system having a first pulley and a biasing member having a first portion operatively coupled to the first pulley. A first tension member can be operatively coupled to the first pulley. The lift system may be configured to provide a constant force to the first tension member during a defined angle of rotation of the first pulley. Such a constant force can be used to counterbalance the weight of a display supported by a stand.
1. A method of changing a position of a display, comprising engaging a display and applying a force to the display, the display being operatively coupled to a lift system comprising a first pulley having an axis of rotation, a biasing member having a biasing member force dependent upon its length, a centerline, and a first portion operatively coupled to the first pulley, a first radius extending between the centerline of the biasing member and the axis of rotation, the first radius continuously changing when the first pulley rotates and the first radius having a value of zero when the biasing member force is at a maximum to create a constant moment output, and a first tension member having a first portion operatively coupled to the first pulley, the constant moment output providing a constant force to the first tension member during a defined angle of rotation of the first pulley.
2. A stand and display in combination, comprising:
a display;
a stand supporting the display, the stand having a base and a vertical member coupled to the base, the vertical member having an inner member and an outer member in sliding or rolling engagement, one of the inner and outer members functionally coupled to the base and the other of the inner or outer members functionally coupled to the display;
a lift system disposed within the stand, the lift system comprising a first pulley having an axis of rotation, a biasing member having a biasing member force dependent upon its length, a centerline, and a first portion operatively coupled to the first pulley, a first radius extending between the centerline of the biasing member and the axis of rotation, the first radius continuously changing when the first pulley rotates and the first radius having a value of zero when the biasing member force is at a maximum to create a constant moment output, and a first tension member having a first portion operatively coupled to the first pulley, the constant moment output providing a constant force to the first tension member during a defined angle of rotation of the first pulley to counterbalance the display.
3. The lift system of claim 2 , wherein a second portion of the first tension member is functionally coupled to the display.
4. The lift system of claim 2 , further including a second pulley having a second pulley radius operatively coupled to the first pulley via a second portion of the first tension member, the second pulley being operatively coupled to a third pulley having a third pulley radius, the third pulley radius being larger than the second pulley radius, the third pulley having a second tension member with a first portion operatively coupled thereto, the lift system being configured to magnify the range of motion of a second portion of the second tension member as the first pulley moves through the defined angle.
5. The lift system of claim 4 , wherein the second pulley and third pulley have coaxial axes of rotation.
6. The lift system of claim 4 , wherein the third pulley radius is at least twice the length of the second pulley radius.
7. The lift system of claim 4 , wherein the second portion of the second tension member is operatively coupled to the display.
8. The lift system of claim 7 , wherein the display is a flat panel display.
9. The lift system of claim 2 , further including a contact member having a contact surface connected to the first pulley and an engagement member useful for engaging the contact surface.
10. The lift system of claim 9 , wherein the contact surface includes a generally helical groove in the contact member and the engagement member includes a rigid protrusion that rides within the groove.
11. The lift system of claim 9 , wherein the contact member includes a camming member having a camming surface and the engagement member is useful for engaging the camming surface.
12. The lift system of claim 2 , wherein the defined angle is less than 180 degrees.
13. The lift system of claim 2 , wherein the defined angle is less than 90 degrees.
14. The lift system of claim 2 , wherein the defined angle is less than 30 degrees.
15. The lift system of claim 2 , wherein the biasing member includes a spring.
16. The lift system of claim 15 , wherein the spring includes an extension spring.
17. The combination of claim 2 , wherein the base defines a cavity to house the biasing member and first pulley.
18. The lift system of claim 2 , wherein the first portion of the first tension member is directly connected to the first pulley.