Patent ID: 9690159
Date: 2017-06-27
CPC Classifications: G02F,G09G,H02M

Claim:
1. A display device having a supply voltage generation function by converting a level of a DC voltage, comprising: a display that displays an image; a drive circuit that drives the display; a first DC-DC converter which includes a first induction element and a first switching element that changes an electric current passing through the first induction element; converts a level of an externally inputted DC voltage by operating the first switching element; and supplies a DC voltage resulted from the conversion to the drive circuit as a first supply voltage; a drive controller that controls the drive circuit; and a power supply controller that controls the first DC-DC converter; wherein the first DC-DC converter switches a control mode that controls an operation of the first switching element with a mode control signal outputted from the power supply controller between at least two control modes including a first mode and a second mode which provides a higher power conversion efficiency than a power conversion efficiency of the first mode under a predetermined light load condition, wherein the drive controller generates a vertical synchronization signal which is activated for a predetermined period per one frame based on an external input signal, and the power supply controller switches the control mode by switching the mode control signal together in synchronization with the vertical synchronization signal so that the first DC-DC converter operates in the first mode when the drive circuit is driving the display, whereas the first DC-DC converter operates in the second mode when the drive circuit is not driving the display; and the control mode is turned to said first mode in synchronization with a first pulse of the vertical synchronization signal and the control mode is turned to said second mode in synchronization with a second pulse of the vertical synchronization signal.