Liquid crystal display apparatus, driving method therefor, and display system

• US 6,873,312 B2
• Filed: 01/17/1997
• Issued: 03/29/2005
• Est. Priority Date: 02/21/1995
• Status: Expired due to Term

• Current Assignee: BOE Technology Group Co., Ltd.
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Matsueda, Yojiro
• Primary Examiner(s): Awad, Amr
• Assistant Examiner(s): ENGLISH, ALECIA DIANE
• Application Number:
  US09/142,659
• Publication Number:
  US 20020145602A1
• Time in Patent Office: 2,993 Days
• Field of Search: 345/92, 345/96, 345/100, 345/98, 345/99, 345/690, 345/147, 345/87
• US Class Current: 345/98
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

An n-bit digital image data is converted to (n+m)-bit data with a g-correction table, and displayed by the use of a (n+m)-bit D/A converter. A peripheral-driver logic section is driven with a low-voltage common power source and countermeasures to noise are taken. Data input to the D/A converter is not reversed and the power to the D/A converter is made alternating to apply an AC voltage to aligned crystal layer. A circuit is provided in order to compensate for a delay time in the driver. With this configuration, the image quality of a liquid crystal display apparatus in which the D/A converter is built is improved.

Claims

1. A liquid crystal display apparatus comprising:

a liquid crystal layer;

a plurality of scanning lines, the plurality of scanning lines being driven by a scanning driver having a first shift register and a first level shifter;

a plurality of signal lines, the plurality of signal lines being driven by a data driver having a second shift register, a second level shifter and a D/A converter;

pixels disposed correspondingly to the intersections of said scanning lines and said signal lines; and

transistors for the pixels,

the first shift register being connected to a common power source, and the second shift register being also connected to the common power source,

signals having voltages between voltages of the common power source being used as logic signals,

voltages of control signals for the D/A converter being increased by the second level shifter prior to D/A conversion, the second shift register in said data driver and the first shift register in said scanning driver connected to the common power source and logic signal inputs for the signal lines being powered by the common power source, and the voltage of said common power source being lower than the voltage of a power source for said D/A converter.

2. The liquid crystal display apparatus according to claim 1,

the transistors for the pixels being thin-film transistors on a substrate,

the data driver having a thin-film transistor formed on said substrate, and

the scanning driver having a thin-film transistor formed on the substrate.

3. The liquid crystal display apparatus according to claim 1, the D/A converter including n capacitors having a capacitance ratio of 1:

2;

4;

. . . ;

2<sup>n−

1</sup> and n switches.

4. The liquid crystal display apparatus according to claim 1, wherein an input section of each of said level shifters is connected to n-channel and p-channel two transistors connected in parallel.

5. A driving method for a liquid crystal display apparatus, the liquid crystal display comprising:

a liquid crystal layer;

a plurality of scanning lines, the plurality of scanning lines being driven by a scanning driver having a first shift register and a first level shifter;

a plurality of signal lines, the plurality of signal lines being driven by a data driver having a second shift register, a second level shifter and a D/A converter;

pixels disposed correspondingly to the intersections of said scanning lines and said signal lines; and

transistors for said pixels, said driving method further comprising;

inputting an image signal input to said D/A converter and a timing signal input to said second shift register having a same amplitude;

switching a power level of said D/A converter alternately in every field period to apply an AC voltage to said liquid crystal layer; and

switching a first and second field period,

in the first field period a voltage of a scanning signal being set at a higher voltage than a non-selection voltage before the voltage of the scanning signal changes from a selection voltage to the non-selection voltage after a selection period, and in the second field period the voltage of the scanning signal being set at a lower voltage than the non-selection voltage before the voltage of the scanning signal changes from the selection voltage to the non-selection voltage after the selection period, the second shift register in said data driver and the first shift register in said scanning driver being connected to a common power source, the image signal input to said D/A converter and the timing signal input to said second shift register being powered by the common power source, and the voltage of said common power source being lower than the voltage of a power source for said D/A converter.

6. A driving method for a liquid crystal display apparatus, the liquid crystal display comprising:

a liquid crystal layer;

a plurality of scanning lines, the plurality of scanning lines being driven by a scanning driver having a first shift register and a first level shifter;

a plurality of signal lines, the plurality of signal lines being driven by a data driver having a second shift register, a second level shifter and a D/A converter;

pixels disposed correspondingly to the intersections of said scanning lines and said signal lines; and

transistors for the pixels, said driving method further comprising;

inputting an image signal input to said D/A converter and a timing signal input to said second shift register having a same amplitude; and

switching a power level of said D/A converter alternately in every field period to apply an AC voltage to said liquid crystal layer,

switching a first and a second horizontal scanning period,

the first horizontal scanning period being followed by a period in which a voltage of a scanning signal is set at a higher voltage than a non-selection voltage, and the second horizontal scanning period being followed by a period in which the voltage of the scanning signal is set at a lower voltage than the non-selection voltage, the second shift register in said data driver and the first shift register in said scanning driver being connected to a common power source, the image signal input to said D/A converter and the timing signal input to said second shift register being powered by the common power source, and the voltage of said common power source being lower than the voltage of a power source for said D/A converter.

7. A driving method for a liquid crystal display apparatus, the liquid crystal display comprising:

a liquid crystal layer;

a plurality of scanning lines, the plurality of scanning lines being driven by a scanning driver having a first shift register and a first level shifter;

a plurality of signal lines, the plurality of signal lines being driven by a data driver having a second shift register, a second level shifter and a D/A converter;

pixels disposed correspondingly to the intersections of said scanning lines and said signal lines; and

transistors for the pixels, said driving method further comprising;

inputting an image signal input to said D/A converter and a timing signal input to said second shift register having a same amplitude; and

switching a power level of said D/A converter alternately in every field period to apply an AC voltage to said liquid crystal layer,

a capacitor-coupling D/A converter being used as the D/A converter, and a digital signal that is not reversed for a black level and white level being used as the image signal input to the D/A converter, the second shift register in said data driver and the first shift register in said scanning driver being connected to a common power source, the image signal input to said D/A converter and the timing signal input to said second shift register being powered by the common power source, and the voltage of said common power source being lower than the voltage of a power source for said D/A converter.

8. A liquid crystal display apparatus comprising:

a first substrate, the first substrate comprising;

a plurality of scanning lines,

a plurality of signal lines,

pixel electrodes disposed correspondingly to the intersections of said scanning lines and said signal lines, and

thin-film transistors for pixels, disposed correspondingly to said pixel electrodes;

a second substrate disposed opposite to said first substrate, the second substrate having a common electrode with the first substrate; and

a liquid crystal layer held between said first substrate and said second substrate, wherein said signal lines are driven by a data driver having a shift register, a level shifter, and a D/A converter, and said scanning lines are driven by a scanning driver having a shift register, a level shifter, and a buffer,

wherein said liquid crystal display apparatus includes the shift register in said data driver and the shift register in said scanning driver connected to a common V_dd and V_ss, and a logic signal of a voltage between the V_dd and V_ss is input for the signal lines and is increased by the level shifter prior to D/A conversion, and

wherein the voltage of said common power source is lower than the voltage of a power source for said D/A converter and said buffer.

9. A driving method for a liquid crystal display apparatus, the liquid crystal display apparatus including:

a first substrate, the first substrate including;

a plurality of scanning lines;

a plurality of signal lines,

pixel electrodes disposed correspondingly to the intersections of said scanning lines and said signal lines, and

transistors for pixels, disposed correspondingly to said pixel electrodes;

a second substrate disposed opposite to said first substrate, the second substrate having a common electrode with the first substrate; and

a liquid crystal layer held between said first substrate and said second substrate, wherein said signal lines are driven by a data driver having a first shift register, a level shifter, and a D/A converter, and said scanning lines are driven by a scanning driver having a second shift register and a level shifter, said driving method comprising;

inputting an image signal input to said D/A converter and a timing signal input to said second shift register having a same amplitude;

switching a power level of said D/A converter alternately in every field period to apply an AC voltage to said liquid crystal layer; and

switching a first and a second field period,

a voltage scanning signal in the first field period being set at a higher voltage than a non-selection voltage before the voltage of the scanning signal changes from a selection voltage to the non-selection voltage after a selection period, and a voltage of the scanning signal in the second field period being set at a lower voltage than the non-selection voltage before a voltage of the scanning signal changes from the selection voltage to the non-selection voltage after the selection period, and in the both field periods a voltage of the common electrode of the second substrate being constant, the second shift register in said data driver and the first shift register in said scanning driver being connected to a common power source, the image signal input to said D/A converter and the timing signal input to said second shift register being powered by the common power source, and the voltage of said common power source being lower than the voltage of a power source for said D/A converter.

10. A driving method for a liquid crystal display apparatus, the liquid crystal display apparatus including:

a first substrate, the first substrate including;

a plurality of scanning lines,

a plurality of signal lines,

pixel electrodes disposed correspondingly to the intersections of said scanning lines and said signal lines, and

transistors for pixels, disposed correspondingly to said pixel electrodes;

a second substrate disposed opposite to said first substrate, the second substrate having a common electrode with the first substrate; and

a liquid crystal layer held between said first substrate and said second substrate, wherein said signal lines are driven by a data driver having a first shift register, a level shifter and a D/A converter, and said scanning lines are driven by a scanning driver having a second shift register and a level shifter, said driving method comprising;

inputting an image signal input to said D/A converter and a timing signal input to said second shift register having a same amplitude;

switching a power level of said D/A converter alternately in every field period to apply an AC voltage to said liquid crystal layer; and

switching a first and a second horizontal scanning period,

the first horizontal scanning period being followed by a period in which a voltage of a scanning signal is set at a higher voltage than a non-selection voltage, and the second horizontal scanning period being followed by a period in which the voltage of the scanning signal is set at a lower voltage than the non-selection voltage, and in the both horizontal scanning periods a voltage of the common electrode of the second substrate being constant, the second shift register in said data driver and the first shift register in said scanning driver being connected to a common power source, the image signal input to said D/A converter and the timing signal input to said second shift register being powered by the common power source, and the voltage of said common power source being lower than the voltage of a power source for said D/A converter.