Liquid crystal display apparatus

• US 5,119,084 A
• Filed: 11/22/1989
• Issued: 06/02/1992
• Est. Priority Date: 12/06/1988
• Status: Expired due to Term

• Current Assignee: Casio Computer Company Limited
• Original Assignee: Casio Computer Company Limited
• Inventors: Kawamura, Masao, Fuse, Takahiro
• Primary Examiner(s): Weldon, Ulysses
• Assistant Examiner(s): WU, XIAO MIN
• Application Number:
  US07/440,496
• Time in Patent Office: 923 Days
• Field of Search: 340/784, 340/765, 340/793, 340/728, 340/744, 350/333, 350/332 R, 358/105, 358/167, 358/236, 358/241
• US Class Current: 345/98
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• 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 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3692 suitable for passive matrices only

Abstract

In a liquid crystal driving apparatus for driving a liquid crystal display panel in accordance with an image signal, the response speed of a liquid crystal display panel is increased so as not to produce an afterimage upon motion image display. A signal is preprocessed by an inverse transfer function of the transfer function of the liquid crystal panel, i.e., signal processing for emphasizing an image change in a timer direction is performed, and the liquid crystal display panel is driven by using the processed data.

Claims

1. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

subtracting means for, for image data constituting one image in units of frames, subtracting a K multiple of image data of the (n-1)th frame from image data of the nth frame, where K is a constant and n is a positive integer;

multiplying means for multiplying data output from said subtracting means by (1/(1l -K))

segment electrode driving means for driving the segment electrodes of said liquid crystal display panel by using data output from said multiplying means; and

common electrode driving means for driving the common electrodes.

2. An apparatus according to claim 1, wherein said segment electrode driving means includes limiting means for limiting the output signal from said multiplying means within a predetermined signal range.

3. An apparatus according to claim 1, further comprising motion detecting means for detecting the amount of change of the image data in accordance with a difference between the image data of the nth frame and the image data of the (n-1)th frame, and setting the constant K within a range in which the amount of change of the image data exceeds a predetermined value.

4. An apparatus according to claim 3, further comprising direction detecting means for detecting the direction of a change in a image data in accordance with a detection result from said motion detecting means, and setting the constant K in accordance with the detected change direction.

5. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

A/D converting means for converting an analog image signal into a digital signal;

one-frame delaying means for delaying the digital signal output from said A/D converting means by one frame;

motion detecting means for checking, in accordance with the difference between the output signal from said A/D converting means and an output signal from said one-frame delaying means, whether the output signal from said A/D converting means is present in a motion image region or a still image region, and outputting a constant K in accordance with the check result;

first multiplying means for multiplying the output signal from said one-frame delaying means by the constant K and outputting the multiplied signal;

subtracting means for subtracting the output signal from said first multiplying means from the output signal from said A/D converting means;

second multiplying means for multiplying an output signal from said subtracting means by a value (1/(1-K));

limiter means for limiting an output signal from said second multiplying means within a predetermined signal range;

segment electrode driving means for driving the segment electrodes of said liquid crystal display by using data output from said limiter means; and

common electrode driving means for driving the common electrodes.

6. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

A/D converting means for converting an analog image signal into a digital signal;

first one-frame delaying means for delaying the digital signal output from said A/D converting means by one frame;

first multiplying means for multiplying an output signal from said one-frame delaying means by a constant K and outputting the multiplied signal;

subtracting means for subtracting the output signal from said first multiplying means from the output signal from said A/D converting means;

second multiplying means for multiplying an output signal from said subtracting means by a value (1/(1-K)) and outputting the multiplied signal;

limiter means for limiting the output signal from said second multiplying means within a predetermined signal range;

second one-frame delaying means for delaying an output signal from said limiter means by one frame;

motion detecting means for checking, in accordance with the difference between the output signal from said A/D converting means and an output signal from said second one-frame delaying means, whether the output signal from said A/D converting means is present in a motion region or a still image region, and outputting the constant K in accordance with the check result;

segment electrode driving means for driving the segment electrodes of said liquid crystal display panel in accordance with an output signal from said limiter means; and

common electrode driving means for driving the common electrodes.

7. An apparatus according to claim 6, wherein said motion detecting means sets the constant K within a range of "0<

K<

1" when said motion detecting means determines that the output signal from said A/D converting means is present in a motion image region, and sets the constant K within a range of "-1<

K<

0" when said motion detecting means determines that the output signal from said A/D converting means is present in a still image region.

8. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

A/D converting means for converting an analog image signal into a digital signal;

subtracting means, having + and - terminals, for receiving an output signal from said A/D converting means at the + terminal thereof;

first multiplying means for multiplying an output signal from said subtracting means by a value (1/(1-K)) and outputting the multiplied signal;

limiter means for limiting the output signal from said first multiplying means within a predetermined signal range;

first one-frame delaying means for delaying an output signal from said limiter means by one frame;

motion detecting means for checking, in accordance with the difference between the output signal from said A/D converting means and an output signal from said first one-frame delaying means, whether the output signal from said A/D converting means is present in a motion image region or a still image region, and outputting a constant K in accordance with the check result;

second multiplying means for multiplying the output signal from said limiter means by a value (1-K) and outputting the multiplied signal;

adding means, having two input terminals, for receiving the output signal from said second multiplying means at one input terminal thereof;

second one-frame delaying means for delaying an output signal from said adding mans by one frame;

third multiplying means for multiplying an output signal from said second one-frame delaying means by the constant K and outputting the multiplication result to the--terminal of said subtracting means and the other input terminal of said adding means;

segment electrode driving means for driving the segment electrodes of said liquid crystal display panel in accordance with an output signal from said limiter means; and

common electrode driving means for driving the common electrodes.

9. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

subtracting means for, for image data constituting one image in units of frames, subtracting image data of the (n-1)th frame from image data of the nth frame;

multiplying means for multiplying data output from said subtracting means by (K/(1-K));

adding means for adding data output from said multiplying means to the data of the nth frame;

segment electrode driving means for driving the segment electrodes of said liquid crystal display panel using data output from said adding means; and

common electrode driving means for driving the common electrodes.

10. An apparatus according to claim 9, further comprising constant generating means for comparing the output data from said subtracting means with a predetermined reference value, determining a still image region when the output data is smaller than the predetermined reference value, and determining a motion image region when the output data is larger than the predetermined reference value.

11. An apparatus according to claim 10, further comprising limiter means, located between said adding means and said segment electrode driving means, for limiting the output signal from said adding means within a predetermined signal range.

12. An apparatus according to claim 9, further comprising:

motion detecting means for comparing the output data from said subtracting means with a predetermined reference value, and determining a still image region when the output data is smaller than the predetermined reference value and determining a motion image region when the output data is larger than the predetermined reference value; and

constant generating means for generating a constant K for each of R, G, and B color signals corresponding to the data of the nth frame on the basis of a detection signal from said motion detecting means.

13. An apparatus according to claim 12, further comprising limiter means, located between said adding means and said segment electrode driving means, for limiting the output signal from said adding means within a predetermined signal range.

14. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

supply means for supplying an image signal;

one-frame delaying means for delaying the image signal supplied from said supplying means by one frame;

motion detecting means for checking, in accordance with the difference between the image signal supplied from said supply means and an output signal from said one-frame delaying means, whether the image signal is present in a motion image region or a still image region, and outputting a constant K in accordance with the check result;

first multiplying means for multiplying the output signal from said one-frame delaying means by the constant K ad outputting the multiplied signal;

subtracting means for subtracting the output signal from said first multiplying means from the image signal from said supply means;

second multiplying means for multiplying an output signal from said subtracting means by a value (1/(1-K)) and outputting the multiplying signal;

limiter means for limiting the output signal from said second multiplying means within a predetermined signal range;

segment electrode driving means for driving the segment electrodes of said liquid crystal display panel using data output from said limiter means; and

common electrode driving means for driving the common electrodes.

15. A liquid crystal display apparatus, comprising:

a liquid crystal display panel having a plurality of common electrodes and a plurality of segment electrodes crossing said common electrodes;

supply means for supplying an image signal;

first one-frame delaying means for delaying the image signal supplied from said supplying means by one frame;

first multiplying means for multiplying the output signal from said first one-frame delaying means by the constant K and outputting the multiplied signal;

subtracting means for subtracting the output signal from said first multiplying means from the image signal from said supply means;

second multiplying means for multiplying an output signal from said subtracting means by a value (1/(1-K)) and outputting the multiplied signal;

limiter means for limiting the output signal from said second multiplying means within a predetermined signal range;

second one-frame delaying means for delaying an output signal from said limiter means by one frame;

motion detecting means for checking, in accordance with the difference between the image signal supplied from said supply means and an output signal from said second one-frame delaying means, whether the image signal is present in a motion image region or a still image region, and outputting a constant K in accordance with the check result;

segment electrode driving means for driving the segment electrodes of said liquid crystal display panel in accordance with an output signal from said limiter means; and

common electrode driving means for driving the common electrodes.