Display control device of liquid crystal panel and liquid crystal display device

• US 20030156092A1
• Filed: 09/30/2002
• Published: 08/21/2003
• Est. Priority Date: 02/20/2002
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Fujitsu Display Technologies Corporation (Fujitsu Limited)
• Inventors: Suzuki, Toshiaki, Katagawa, Koichi, Yuda, Takashi, Kojima, Toshihiro, Yonemura, Koshu
• Granted Patent: US 6,894,669 B2
• Time in Patent Office: Days
• US Class Current: 345/98
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/3685 Details of drivers for data electrodes

Abstract

An operational unit determines, for subfield(s) other than a last subfield of a plurality of subfields constituting a single frame period, based on a difference determined by a data comparison unit, exceeded display data for setting the transmittance of each pixel to a value exceeding a target transmittance corresponding to image data supplied anew. The operational unit also determines, for the last subfield of the single frame period, based on the difference determined by the data comparison unit, target display data for setting the transmittance of each pixel to the target transmittance. An overshoot operation or operations are performed within the single frame period, and each pixel is set to the transmittance corresponding to the image data. This makes it possible to avoid trails occurring in moving image display and enhance the appearance of moving image display with no increase in frame rate.

Claims

1. A display control device of a liquid crystal panel, comprising:

a data memory unit for storing image data to be supplied correspondingly to each single frame period for which a single frame of the liquid crystal panel is displayed;

a data comparison unit for determining, on each pixel of said liquid crystal panel, a difference between image data supplied anew and image data of a frame immediately preceding and stored in said data memory unit;

an operational unit for determining, for subfield(s) of a plurality of subfields other than a last subfield, based on said difference, exceeded display data for setting the transmittance of said each pixel to a value greater than a target transmittance corresponding to image data supplied anew, the plurality of subfields constituting said single frame period, and for determining, for said last subfield of said single frame period, based on said difference, target display data for setting the transmittance of said each pixel to said target transmittance; and

a timing control unit for generating timing signals synchronizing with each of said plurality of subfields, receiving said exceeded display data and said target display data in succession from said operational unit, and outputting, in synchronization with said timing signals, driving signals of said liquid crystal panel according to the received display data.

2. The display control device of a liquid crystal panel according to claim 1, wherein

said target display data which said operational unit determines for said last subfield corresponds to an exceeded applied voltage which exceeds a target applied voltage to be applied to said liquid crystal panel so as to set the transmittance of said each pixel to said target transmittance.

3. The display control device of a liquid crystal panel according to claim 2, further comprising a first memory unit, and wherein

said operational unit includes

a first operational unit for determining said exceeded display data corresponding to a first subfield of said single frame period,

a second operational unit for determining, for said last subfield, a difference between said target display data corresponding to said exceeded applied voltage and display data corresponding to said target applied voltage, and for storing the determined difference into said first memory unit, and

a third operational unit for determining said target display data corresponding to said exceeded applied voltage, according to said difference stored in said first memory unit and said image data stored in said data memory unit.

4. The display control device of a liquid crystal panel according to claim 3, further comprising a second memory unit, and wherein:

said single frame period includes three or more subfields; and

said operational unit includes

a fourth operational unit for determining, for intermediate subfield(s), a difference between display data corresponding to said target applied voltage and said exceeded display data, and for storing the determined difference into said second memory unit, the intermediate subfield(s) being of said single frame period other than said first and last subfields, and

a fifth operational unit for determining said exceeded display data corresponding to said intermediate subfield(s), according to said difference stored in said second memory unit and said image data stored in said data memory unit.

5. The display control device of a liquid crystal panel according to claim 1, wherein

said operational unit generates said exceeded display data and said target display data both of which allow an average of transmittance in said single frame period to be substantially equal to said target transmittance.

6. The display control device of a liquid crystal panel according to claim 1, wherein

a maximum value of said target transmittance is smaller than a transmittance corresponding to a maximum value of said exceeded display data which said operational unit is able to output.

7. The display control device of a liquid crystal panel according to claim 1, wherein

lengths of periods of said subfields are equal to each other.

8. The display control device of a liquid crystal panel according to claim 1, wherein

a length of a period of said first subfield is shorter than lengths of periods of the rest of said subfields in said single frame period.

9. The display control device of a liquid crystal panel according to claim 1, comprising:

a temperature detecting unit for detecting an ambient temperature of said liquid crystal panel; and

a temperature memory unit for storing temperature correcting values corresponding to individual ambient temperatures to be detected by said temperature detecting unit, and wherein

said first and second operational units correct said exceeded display data and said target display data according to said temperature correcting values which are output from said temperature memory unit and correspond to the ambient temperatures detected by said temperature detecting unit.

10. The display control device of a liquid crystal panel according to claim 1, comprising:

a rate detecting unit for detecting a frame rate, which is said single frame period; and

a rate memory unit for storing rate correcting values corresponding to frame rates to be detected by said rate detecting unit, and wherein

said first and second operational units correct said exceeded display data and said target display data according to said rate correcting values which are output from said rate memory unit and correspond to the frame rates detected by said rate detecting unit.

11. A liquid crystal display device comprising:

a liquid crystal panel;

a data memory unit for storing image data to be supplied correspondingly to each single frame period for which a single frame of the liquid crystal panel is displayed;

a data comparison unit for determining, on each pixel of said liquid crystal panel, a difference between image data supplied anew and image data of a frame immediately preceding and stored in said data memory unit;

an operational unit for determining, for subfield(s) of a plurality of subfields other than a last subfield, based on said difference, exceeded display data for setting the transmittance of said each pixel to a value greater than a target transmittance corresponding to image data supplied anew, the plurality of subfields constituting said single frame period, and for determining, for said last subfield of said single frame period, based on said difference, target display data for setting the transmittance of said each pixel to said target transmittance; and

a timing control unit for generating timing signals synchronizing with each of said plurality of subfields, receiving said exceeded display data and said target display data in succession from said operational unit, and outputting, in synchronization with said timing signals, driving signals of said liquid crystal panel according to the received display data.