Data interface device

• US 6,720,943 B1
• Filed: 09/14/1999
• Issued: 04/13/2004
• Est. Priority Date: 04/12/1999
• Status: Expired due to Term

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Kim, Yu Soong, Kim, Seong Jin, Lee, Hyun Chang
• Primary Examiner(s): CHOW, DOON Y
• Application Number:
  US09/395,639
• Time in Patent Office: 1,673 Days
• Field of Search: 345/87, 345/99, 345/204, 345/211, 345/212, 345/213, 709/231, 363/41, 375/376, 327/144, 359/265, 325/204
• US Class Current: 345/87
• CPC Class Codes: G09G 5/006 Details of the interface to the display terminal specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04
• CPC Class Codes: G09G 5/18 Timing circuits for raster scan displays specially adapted for television H04N ; synchronisation between the display unit and other display units, videodisc player G09G5/12
• CPC Class Codes: H04B 15/04 the interference being caused by substantially sinusoidal oscillations, e.g. in a receiver or in a tape-recorder
• CPC Class Codes: H04B 2215/064 Reduction of clock or synthesizer reference frequency harmonics
• CPC Class Codes: H04B 2215/067 by modulation dispersion

Abstract

A data interface device is constructed to minimize electromagnetic interference in a liquid crystal display device. The data interface device has a data input arranged to input data which is synchronized with a desired frequency of a data clock. A clock modulator modulates the data clock to provide a modulated clock signal having a frequency within a certain range of frequency so as to minimize EMI when data is transmitted using the data clock. A variable data transmission speed controller responds to the data clock and the modulated clock in such a manner that a transmission speed of the data is varied in a manner to minimize EMI.

Claims

1. A data interface apparatus for a display device, comprising:

a data input supplying data signals;

a data driver responsive to a control signal and arranged to drive the display device;

a clock modulator arranged to modulate a base clock and to provide a modulated clock having a frequency which is varied within a frequency band of about ±

x% of a base clock frequency where 1≦

x≦

50; and

a data transmission unit arranged to receive the data signals from the data input in response to the base clock and to transmit the data signals to the data driver according to the modulated clock such that a data transmission speed of the data signals is varied to reduce EMI,

wherein the modulated clock is commonly applied to the data transmission unit and the data driver, and the data driver simultaneously transfers the data signals to the display device in response to the modulated clock and the control signal.

2. A data interface apparatus according to claim 1, wherein the modulated clock is provided for transmitting the data signals according to a certain timing defined by the modulated clock, and the data transmission unit is adapted to vary a speed of the modulated clock to reduce EMI.

3. A data interface apparatus according to claim 1, wherein the data transmission unit varies the speed of the modulated clock according to a predetermined pattern.

4. A data interface apparatus according to claim 3, wherein the pattern is based on one of a triangular waveform, a sinusoidal waveform, a symmetric waveform, an asymmetric waveform, and a pattern including multiple different frequencies.

5. A data interface apparatus according to claim 1, wherein the clock modulator is integral with the data transmission unit.

6. A data interface apparatus according to claim 5, wherein the clock modulator comprises one of an electronic circuit, an IC chip, an ASIC chip and a plurality of electronic circuit elements.

7. A data interface apparatus according to claim 5, wherein the data transmission unit clock includes a frequency divider arranged to modulate the modulated clock and to provide a second modulated clock commonly applied to the data driver and the data transmission unit, the second modulated clock being synchronized with the modulated clock.

8. A data interface apparatus according to claim 7, further comprising a data timing controller responsive to the modulated clock and arranged to transfer the data such that a data transmission speed is varied within a certain range.

9. A display apparatus, comprising:

a data input supplying data signals;

a data driver responsive to a control signal and arranged to drive a display panel with the data signals;

a clock modulator arranged to modulate a base clock and to provide a modulated clock having a frequency which is varied within a frequency band of about ±

x% of a base clock frequency where 1≦

x≦

50; and

a data transmission unit arranged to receive the data signals from the data input in response to the base clock and to transmit the data signals to the data driver according to the modulated clock such that a data transmission speed of the data signals is varied to reduce EMI,

wherein the modulated clock is commonly applied to the data transmission unit and the data driver, and the data driver simultaneously transfers the data signals to the display device in response to the modulated clock and the control signal.

10. The display apparatus according to claim 9, wherein the display panel is a liquid crystal display.

11. The display apparatus according to claim 9, wherein the display panel is a monitor including a liquid crystal display.

12. A liquid crystal panel driving apparatus, comprising:

a video data input arranged to input video data;

source driving circuits responsive to a control signal and arranged to drive data lines of the liquid crystal panel;

a clock modulator arranged to modulate a base clock and to provide a modulated clock having a frequency which is varied within a frequency band of about ±

x% of a base clock frequency where 1≦

x≦

50; and

a data interface arranged to receive the video data responsive to the base clock and transmit the video data to the source driving circuits according to the modulated clock in such a manner that a transmission speed of the video data is varied to reduce EMI,

wherein the modulated clock is commonly applied to the data transmission unit and the data driver, and the data driver simultaneously transfers the data signals to the display device in response to the modulated clock and the control signal.

13. A liquid crystal panel driving apparatus, comprising:

a data input arranged to input a video data synchronized with a desired frequency of data clock;

source driving circuits responsive to a control signal and arranged to drive data lines of the liquid crystal panel;

a clock modulator arranged to modulate the data clock and to provide a modulated clock having a frequency which is varied within a frequency band of about ±

x% of the data clock frequency, where 1≦

x≦

50, to reduce EMI; and

a data timing controller arranged to receive the video data in response to the data clock transfer the video data to the source driving circuits such that a transmission speed is varied within a certain range,

wherein the modulated clock is commonly applied to the data interface and the source driving circuits, and the source driving circuits simultaneously transfer the video data to the display device in response to the modulated clock and the control signal.

14. A monitor apparatus, comprising:

a video data input arranged to input video data;

a data driver arranged to drive a display panel with the video data;

a clock modulator arranged to modulate a base clock and to provide a modulated clock having a frequency which is varied within a frequency band of about ±

x% of a base clock frequency where 1≦

x≦

50; and

a data scaler arranged to scale the video data received from the data input and to supply the scaled video data to the data driver according to the first modulated clock such that a transmission speed of the data is varied within a certain range, wherein the data scaler generates a second modulated clock synchronized with the first modulated clock and outputs the second modulated clock,

wherein the data driver simultaneously transfers the scaled video data to the display panel in response to the second modulated clock.

15. The monitor apparatus as claimed in claim 14, wherein the display panel includes a liquid crystal panel.

16. A monitor apparatus, comprising:

a video data input arranged to input a video data synchronized with a frequency of a data clock;

a data driver arranged to drive a display panel with the video data;

a clock modulator arranged to modulate the data clock to provide a first modulated clock having a frequency which is varied within a frequency band of about ±

x% of the data clock frequency where 1≦

x≦

50; and

a data scaler responsive to the data clock to scale the video data from the data input and responsible to the first modulated clock to supply the scaled video data to the data driver such that a transmission speed is varied within a certain range, wherein the data scaler generates a second modulated clock synchronized with the first modulated clock and outputs the second modulated clock,

wherein the data driver simultaneously transfers the scaled video data to the display panel in response to the second modulated clock.

17. The monitor apparatus as claimed in claim 16, wherein the display panel includes a liquid crystal display panel.

18. A monitor apparatus, comprising:

a signal converter arranged to convert an analog video signal into digital video data;

a data driver arranged to drive a monitor with the video data;

a clock generator arranged to generate a sampling clock;

a clock modulator arranged to modulate the sampling clock into a first modulated clock having a frequency which is varied within a frequency band of about ±

x% of the sampling clock frequency where 1≦

x≦

50 and to apply the first modulated clock to the signal converter, to thereby vary a transmission speed of the digital data within a certain speed range, wherein the signal converter receives the first modulated clock, and generates a second modulated clock having a desired phase difference from the first modulated clock and outputs the second modulated clock; and

a data scaler responsive to the second modulated clock and arranged to scale the video data from the signal converter and to supply the scaled video data to the data driver, wherein the data scaler generates a third modulated clock having a desired phase difference from the second modulated clock and outputs the third modulated clock to the data driver,

wherein the data driver simultaneously transfers the scaled video data to the display panel in response to the third modulated clock.

19. The monitor apparatus as claimed in claim 18, wherein the display panel includes a liquid crystal panel.