Display apparatus driving circuitry
View Patent ↗A display apparatus driving circuitry for driving a plasma display panel. A first transistor is electrically connected between an output terminal and a high-voltage power supply terminal. A second transistor is connected between the output terminal and a reference power supply terminal. A buffer circuit supplies a voltage lower than a low voltage VDL for logic to a gate of the second transistor to make a drop in an output waveform gradual during an address electrical discharge. In a preferred embodiment, during this drop in the output waveform, a p-channel type MOSFET of the buffer circuit is turned on, whereby the VDL is suppressed due to a back gate effect. Therefore, a signal at a potential lower than the VDL is inputted to the gate of the second transistor. As a result, the drop in the second transistor output waveform is gradual, so that noise and damage are prevented.
1. Display apparatus driving circuitry, comprising:
an output terminal;
a high-voltage power supply terminal for supplying a high voltage;
a first low-voltage power supply terminal for supplying a first low voltage for logic;
a second low-voltage power supply terminal for supplying a second low voltage;
a reference power supply terminal;
a first transistor electrically connected between the output terminal and the high-voltage power supply terminal;
a second transistor connected between the output terminal and the reference power supply terminal; and
a buffer circuit comprising
a first p-channel type MOS field effect transistor (PMOS) electrically connected to the first low-voltage power supply terminal,
a second p-channel type MOS field effect transistor (PMOS) electrically connected to the second low-voltage power supply terminal,
a first NMOS electrically connected between (a) a drain of the first PMOS and a drain of the second PMOS and (b) a gate of the second transistor, and
a second NMOS electrically connected between the gate of the second transistor and the reference power supply terminal.
2. The display apparatus driving circuitry according to claim 1 , wherein the buffer circuit varies the gate voltage of the second transistor by turning one of the first PMOS and the second PMOS on and turning the other one of the first PMOS and the second PMOS off.
3. The display apparatus driving circuitry according to claim 2 , wherein the buffer circuit includes a delay circuit that controls a time period for the turning on and off of the first PMOS and the second PMOS.
4. The display apparatus driving circuitry according to claim 1 , further comprising a Zener diode between the gate of the second transistor and the reference power supply terminal, for protecting the gate of the second transistor.
5. The display apparatus driving circuitry according to claim 1 , the second low voltage is produced from the first low voltage.
6. The display apparatus driving circuitry according to claim 1 ,
wherein the first transistor and the second transistor are insulated gate bipolar transistors.