Abstract: A folding lens system includes: a polarization-dependence device, a first optical device, a first polarization controller, a second optical device and a second polarization controller. The polarization-dependence device has a first surface and a second surface opposite to the first surface. The first optical device is located at a side facing toward the first surface of the polarization-dependence device. The first polarization controller is located between the polarization-dependence device and the first optical device. The first polarization controller has the same curvature as the first surface of the polarization-dependence device. The second optical device is located at a side facing toward the second surface of the polarization-dependence device. The second polarization controller is located between the polarization-dependence device and the second optical device. The second polarization controller has the same curvature as the second surface of the polarization-dependence device.

Abstract: A folding lens system includes: a polarization-dependence device, a first optical device, a first polarization controller, a second optical device and a second polarization controller. The polarization-dependence device has a first surface and a second surface opposite to the first surface. The first optical device is located at a side facing toward the first surface of the polarization-dependence device. The first polarization controller is located between the polarization-dependence device and the first optical device. The first polarization controller has the same curvature as the first surface of the polarization-dependence device. The second optical device is located at a side facing toward the second surface of the polarization-dependence device. The second polarization controller is located between the polarization-dependence device and the second optical device. The second polarization controller has the same curvature as the second surface of the polarization-dependence device.

Abstract: A negative voltage switch includes a switch unit, a voltage level converting circuit, and a discharge circuit. The switch unit has an input terminal for receiving a negative input voltage and an output terminal coupled to a load. The voltage level converting circuit receives a control signal and switches the switch unit to a first state or a second state according to the control signal. The switch circuit is switched to the first state if the level of the control signal is higher than a predetermined level and is switched to the second state if the level of the control signal is lower than the predetermined level, and the predetermined level is higher than the level of the negative input voltage.

Abstract: A DC voltage converter used for producing a driving voltage to drive a load comprising a step-up circuit and a modulation circuit is provided. The step-up circuit is used for receiving an input voltage and boosting the input voltage to produce an output voltage. The output voltage is controlled according to a feedback voltage indicative of state of the load. The modulation circuit is electrically connected to the step-up circuit and transforms the output voltage into the driving voltage with a higher voltage level so as to further increase the voltage level of the already boosted output voltage.