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Source driving circuit for preventing gamma coupling

a driving circuit and source technology, applied in the field of display, can solve the problems of abnormal operation of the source driver, inaccurate output voltage of the analog converter b>130/b> to the display panel,

Inactive Publication Date: 2010-03-04
HIMAX TECH LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The solution effectively prevents gamma coupling and short currents during signal transitions, ensuring accurate voltage output and stable operation of the source driver, thereby enhancing the reliability of the display panel.

Problems solved by technology

However, the transition state of the level shifter may trigger the digital-to-analog converter 130 to output inaccurate voltage to the display panel.
The unexpected situation may cause the abnormal operation of the source driver.

Method used

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  • Source driving circuit for preventing gamma coupling
  • Source driving circuit for preventing gamma coupling
  • Source driving circuit for preventing gamma coupling

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Embodiment Construction

[0023]Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

[0024]In embodiments of the invention, during transition of input signals, DACs inside the source driving circuit will be in high-impedance states to improve gamma coupling and short current.

[0025]It is found by the inventor that under some circumstances the digital-to-analog converter may output inaccurate voltage due to a gamma couple effect in the conventional source driver. The gamma couple effect is explained in the FIGS. 2-4. FIG. 2A is a circuit diagram of a conventional level shifter. FIG. 2B illustrates a timing diagram of the level shifter while the input signal IN is changing from logic low (0) to logic high (1). At period t1, the input signal IN is in logic low (0) and the output signal OUT is thus...

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PUM

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Abstract

During transition, level shifters in a source driver output logic high signals to PMOS DACs and output logic low signals to NMOS DACs for shutting down current paths in the PMOS DACs and in the NMOS DACs. Therefore, during transition, the PMOS DACs and the NMOS DACs are at high-impedance stage for preventing gamma coupling effect.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of Invention[0002]The present invention relates to a display, and more particularly to a source driving circuit in the display.[0003]2. Description of Related Art[0004]Various types of electronic devices have display devices, such as TVs, laptop computers, monitors and mobile communication terminals. The display devices are requested to be thin and / or light in order to save the volume and the cost of the electronic devices. To satisfy these requirements, various Flat Panel Displays (FPDs) have been developed as alternatives to more conventional cathode ray tube displays. A Liquid Crystal Display (LCD) is one kind of Flat Panel Display. The LCD device includes a timing controller, a gate driver, a display panel and a source driver.[0005]Generally, digital video data are transmitted to the LCD device from an external host system, e.g., a graphic source. The video data format is converted by the timing controller of the LCD device, and transmit...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H03K3/00H03L5/00
CPCH03K3/35613
Inventor LEE, CHING-CHUNG
Owner HIMAX TECH LTD