Light emitting device and method for driving light emitting device

A method for driving a light emitting device having a plurality of light emitting elements, wherein the light emitting device is switchable in a first state and a second state and has a first portion of the plurality of light emitting elements and a second portion of the plurality of light emitting elements, and the method comprises:

• driving the first portion of the plurality of light emitting elements for emitting first lights;
• and
• providing an optical element to guide the first lights generating from the first portion of the plurality of light emitting elements for switching the light emitting device in the first state;
• wherein in the first state, the light emitting device has output lights, a first intensity of the output lights is measured at a viewing angle of 0°, a second intensity of the output lights is measured at a viewing angle of θ2 and an azimuth angle of Φ2, and a ratio of the second intensity to the first intensity is less than or equal to 0.1, wherein θ2 ranges from 30° to 60°, and Φ2 is 14° or 166°.