# US 8,786,538 B2 · Display device and method for controlling gate pulse

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- Number: US 8,786,538 B2
- Document ID: US8786538B2
- Status: Granted
- Kind: B2
- Application number: 12/977,453
- Filed: 2010-12-23
- Published: 2011-06-30
- Granted: 2014-07-22
- Earliest claimed: 2009-12-30
- Assignees: LG Display Co., Ltd.
- Applicants: Sunguk Byun; Keuksang Kwon; Nakjin Seong; Sangsoo Han; Kyuman Lee; Dongkyoon Heo
- Inventors: Sunguk Byun; Keuksang Kwon; Nakjin Seong; Sangsoo Han; Kyuman Lee; Dongkyoon Heo
- Web page: https://patentgrep.com/patent/US8786538B2

## CPC

- G09G 3/3677: {suitable for active matrices only}
- G09G 2300/0426: Layout of electrodes and connections
- G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit
- G09G 2310/066: Waveforms comprising a gently increasing or decreasing portion, e.g. ramp
- G09G 2320/0219: Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling
- G09G 2330/021: Power management, e.g. power saving
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

A display device comprises a display panel including data lines and gate lines crossing each other, a data driving circuit configured to convert digital video data into data voltages which are supplied to the data lines, a gate driving circuit configured to sequentially supply gate pulses to the gate lines, wherein a voltage of each of the gate pulses increases from a gate low voltage to a precharging voltage during a first rising time and thereafter increases from the precharging voltage to a gate high voltage during a second rising time, and wherein the voltage of each of the gate pulses decreases from the gate high voltage to the precharging voltage during a first falling time and thereafter decreases from the precharging voltage to the gate low voltage during a second falling time.

## Claims

### Claim 1

A display device comprising:
a display panel assembly including data lines and gate lines intersecting each other;
a data driving circuit configured to convert digital video data into data voltages which are supplied to the data lines;
a gate driving circuit configured to sequentially supply gate pulses to the gate lines,
wherein a voltage of each of the gate pulses increases from a gate low voltage to a precharging voltage during a first rising time all along the gate lines and thereafter increases from the precharging voltage to a gate high voltage during a second rising time all along the gate lines, and
wherein the voltage of each of the gate pulses decreases from the gate high voltage to the precharging voltage during a first falling time all along the gate lines and thereafter decreases from the precharging voltage to the gate low voltage during a second falling time all along the gate lines,
a timing controller which supplies the digital video data to the data driving circuit and controls operation timings of the data driving circuit and the gate driving circuit,
wherein the timing controller generates gate shift clocks swinging in a TTL logic voltage level and a power sharing control signal for controlling the gate pulses,
wherein the gate driving circuit comprises:
a level shifter configured to convert the gate shift clocks into the gate pulses under the control of the timing controller; and
a shift register configured to sequentially supply the gate pluses output from the level shifter to the gate lines,
wherein the level shifter comprises:
a first node configured to be applied with the precharging voltage;
a second node configured to output the gate pulses;
a power sharing switch circuit configured to be connected between the first node and the second node, applied with the precharging voltage via the first node, form a current path between first node and the second node during the first rising time and the first falling time, and block the current path between the first node and the second node during the second rising time and the second falling time;
a first transistor configured to be connected to the power sharing switch circuit and the second node and applied with the gate high voltage;
a second transistor configured to be connected to the power sharing switch circuit and the second node and applied with the gate low voltage; and
a switch controller configured to control operation timings of the power sharing switch circuit, the first transistor, and the second transistor, in response to the gate shift clocks and the power sharing control signal.

### Claim 2 (depends on 1)

The display device of claim 1, wherein a rising waveform of each of the gate pulses has a first inflection point between the first rising time and the second rising time.

### Claim 3 (depends on 1)

The display device of claim 1, wherein a falling waveform of each of the gate pulses has a second inflection point between the first falling time and the second falling time.

### Claim 4 (depends on 1)

The display device of claim 1, wherein a slope of a voltage varying during the first rising time is smaller than a slope of a voltage varying during the second rising time, at the rising edge of each of the gate pulses.

### Claim 5 (depends on 1)

The display device of claim 1, wherein a slope of a voltage varying during the first falling time is smaller than a slope of a voltage varying during the second falling time, at the falling edge of each of the gate pulses.

### Claim 6 (depends on 1)

The display device of claim 1, wherein a voltage at the rising edge of each of the gate pulses during the first rising time increases in a step waveform.

### Claim 7 (depends on 1)

The display device of claim 1, wherein a voltage at the falling edge of each of the gate pulses during the first falling time decreases in a step waveform.

### Claim 8 (depends on 1)

The display device of claim 1, wherein a voltage at the rising edge of each of the gate pulses during the first rising time increases in a sinusoidal waveform.

### Claim 9 (depends on 1)

The display device of claim 1, wherein a voltage at the falling edge of each of the gate pulses during the first falling time decreases in a sinusoidal waveform.

### Claim 10 (depends on 1)

The display device of claim 1, wherein the level shifter further comprises a delay circuit which delays control signals output from the switch controller.

### Claim 11 (depends on 10)

The display device of claim 10, wherein the level shifter is provided with an option terminal, and
wherein the switch controller selectively makes the first falling time and the rising time inactive depending on a voltage at the option terminal.

### Claim 12 (depends on 11)

The display device of claim 11, wherein the timing controller applies a power sharing option signal to the option terminal to control waveforms of the gate pulses during the first rising time and the first falling time.

### Claim 13 (depends on 1)

The display device of claim 1, wherein the power sharing switch circuit comprises:
a first diode configured to be connected to the first node and turned on during the first rising time to allow a third node between the first node and the second node to be connected to the first node;
a third transistor configured to be connected to an anode of the first diode via the first nod and turned on to allow the third node to be connected to the first node during the first falling time under the control of the switch controller;
a second diode configured to be connected between the third node and the second node and turned on to allow the second node to be connected to the third node during the first falling time; and
a fourth transistor configured to be connected to a cathode of the second diode via the third node and connected to an anode of the second diode via the second node, and turned on to allow the third node to be connected to the second node during the first rising time under the control of the switch controller.

### Claim 14 (depends on 13)

The display device of claim 13, wherein the first transistor is turned on to allow the gate high voltage to be applied to the second node during the second rising time under the control of the switch controller, and
wherein the second transistor is turned on to allow the gate low voltage to be applied to the second node during the second falling time under the control of the switch controller.

### Claim 15 (depends on 1)

The display device of claim 1, wherein the display panel assembly is provided with a TFT array where pixels and optical sensors for displaying video data are embedded.

### Claim 16 (depends on 1, 2, 3, 4, 5, 6, 7, 8, 9)

The display device of claims 1 to 9, and 10 to 15, wherein the display device is one of a liquid crystal display (LCD), an organic light emitting diode (OLED) display, a field emission display (FED), and an electrophoresis display (EPD).

### Claim 17

A method for controlling gate pulses in a display device having a display panel including data lines and gate lines intersecting each other; a data driving circuit configured to convert digital video data into data voltages which are supplied to the data lines; and a gate driving circuit configured to sequentially supply gate pulses to the gate lines, the method comprising:
increasing voltages of the gate pulses from a gate low voltage to a precharging voltage during a first rising time all along the gate lines;
increasing the voltages of the gate pulses from the precharging voltage to a gate high voltage during a second rising time all along the gate lines;
decreasing the voltages of the gate pulses from the gate high voltage to the precharging voltage during a first falling time all along the gate lines;
decreasing the voltages of the gate pulses from the precharging voltage to the gate low voltage during a second falling time all along the gate lines,
supplying the digital video data to the data driving circuit,
controlling operation timings of the data driving circuit and the gate driving circuit, and
generating gate shift clocks swinging in a TTL logic voltage level and a power sharing control signal for controlling the gate pulses,
wherein the gate driving circuit comprises:
a level shifter configured to convert the gate shift clocks into the gate pulses under the control of the timing controller; and
a shift register configured to sequentially supply the gate pluses output from the level shifter to the gate lines,
wherein the level shifter comprises:
a first node configured to be applied with the precharging voltage;
a second node configured to output the gate pulses;
a power sharing switch circuit configured to be connected between the first node and the second node, applied with the precharging voltage via the first node, form a current path between first node and the second node during the first rising time and the first falling time, and block the current path between the first node and the second node during the second rising time and the second falling time;
a first transistor configured to be connected to the power sharing switch circuit and the second node and applied with the gate high voltage;
a second transistor configured to be connected to the power sharing switch circuit and the second node and applied with the gate low voltage; and
a switch controller configured to control operation timings of the power sharing switch circuit, the first transistor, and the second transistor, in response to the gate shift clocks and the power sharing control signal.