Apparatus, system and method for detecting a position of a movable object in a device and using the same for controlling the device

A method for detecting a position of a movable object and using the position to control a device wherein the movable object is connected to a shaft in the device and further wherein the movable object rotates with the shaft, the method comprising:

• focusing light from only one light source having an intensity onto a target on the movable object;
• reflecting the light off the target on the movable object;
• detecting via only one detector the light reflected off the target on the movable object;
• measuring via the one detector a change in the intensity of the detected light reflected off the target on the movable object;
• providing oil in a cavity of the movable object adjacent to the one light source, the movable object including a top surface, a bottom surface, and sides connecting the top surface to the bottom surface forming the cavity, wherein the one light source emits the light into the cavity, wherein the cavity has non-constant height defined by the top surface and the bottom surface, wherein a distance at which the detected light travels in the cavity varies according to the non-constant height of the cavity, wherein the target is the bottom surface of the cavity, and wherein the change in the intensity of the detected light corresponds to a change in the distance at which the detected light travels in the cavity;
• producing a signal indicative of the rotation of the movable object and the shaft;
• and
• determining the position of the movable object from the signal.

An apparatus for detecting a signal indicative of a position of a movable object in a device, the apparatus comprising:

• only one light source remote from the movable object wherein the one light source emits light having an intensity and further wherein the light reflects off the movable object;
• only one detector positioned to detect the light reflected off the movable object and measure the intensity of the detected light reflected off the movable object;
• and
• a cavity of the movable object adjacent to the one light source and comprising a top surface, a bottom surface, and sides connecting the top surface to the bottom surface,
• wherein the cavity contains oil and the one light source emits the light into the cavity,
• wherein the cavity has a non-constant height defined by the top surface and the bottom surface,
• wherein a distance at which the detected light travels in the cavity varies according to the non-constant height of the cavity, and
• wherein a change in the intensity of the detected light corresponds to a change in the distance at which the detected light travels in the cavity.