Semiconductor Display Device with Wide Bandgap Transistor for Power Saving

The patent implements dynamic power management by enabling the driver circuit and control circuits (panel controller, image memory, CPU) to alternately operate between active and stop states. The circuit dynamically switches between writing image signals and stopping operations based on whether image signal writing is required, thereby reducing power consumption during periods when continuous writing is not necessary while maintaining continuous image display capability through the transistor's charge holding function.

The patent employs periodic operation cycles where the driver circuit and control circuits perform image signal writing operations at specific intervals rather than continuously. During periods when image signals do not need to be rewritten (such as when displaying still images), the circuits stop operating to save power, while the transistor maintains the displayed image by holding the charge, creating a periodic pattern of active and inactive states.

The patent introduces a transistor with extremely low off-state current as an intermediary charge holding element between the driver circuit and the display element. This transistor acts as a mediator that retains the electrical charge (and thus the image data) even when power supply is stopped to other circuits. The intermediary transistor preserves the data in the form of held charge, preventing information loss during power-saving modes.

The patent extracts the data retention function from the continuously powered driver circuit and control circuits, and assigns it to a separate transistor element specifically designed for charge holding. By separating the data holding function from the active writing circuits, the system can stop power supply to the writing circuits while maintaining data retention through the dedicated transistor, thus reducing power consumption without losing information.

The patent changes the material parameter of the transistor's channel formation region by using a semiconductor with a wider bandgap than conventional silicon semiconductors. This parameter change (bandgap width) fundamentally alters the transistor's electrical characteristics, resulting in extremely low off-state current. By modifying the material parameter rather than adding complex structural elements, the patent achieves low power consumption while maintaining a relatively simple transistor structure.

The patent employs composite material strategies by combining a wide-bandgap semiconductor material with conventional transistor structures. The channel formation region uses a specialized semiconductor material with wider bandgap properties, while other parts of the transistor may use conventional materials. This composite approach enables the transistor to achieve extremely low off-state current characteristics necessary for power saving while maintaining compatibility with existing manufacturing processes and structural designs.