Input device with optical module for determining a relative position of an object thereon

An input device, comprising:

• an optical module, comprising:
• a light guide plate, being made of a transparent material, having a top surface, a bottom surface opposite the top surface, and a side, wherein the transparent material makes the light travel in a way of total reflection between the top surface and the bottom surface within the light guide plate;
• a light source, being disposed adjacent to the side of the light guide plate to emit a light to the side, the light traveling within the light guide plate;
• a scattering layer, being formed on the bottom surface and being configured to change a reflection path of the partial light hitting on the bottom surface so that the partial light is projected out of the top surface by the scattering layer to form a penetrating light;
• and
• a sensor, having a viewing angle covering at least a part of the bottom surface of the light guide plate, wherein when an object approaches or touches the top surface of the light guide plate, at least a part of the penetrating light is reflected by the object to form a reflected light passing through the light guide plate and then being received by the sensor, and the input device generates a position signal according to the reflected light, the position signal indicating at least one relative position of the object with respect to the top surface of the light guide plate;
• wherein the sensor further continuously receives the reflected light so that the input device determines a variance of the at least one relative position over time according to the position signal;
• wherein the input device is a mouse, the optical module is used as a mouse wheel, and the variance is used by the input device to generate a control signal which represents one of a 360° scroll action, a click action and a combination thereof.