Liquid crystal display apparatus

• US 8,552,930 B2
• Filed: 12/16/2003
• Issued: 10/08/2013
• Est. Priority Date: 10/25/1999
• Status: Expired due to Fees

• Current Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hitachi Displays Limited (Japan Display Incorporated), Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Yamamoto, Tsunenori, Aratani, Sukekazu, Yoneya, Makoto
• Primary Examiner(s): Mengistu, Amare
• Assistant Examiner(s): LAM, VINH TANG
• Application Number:
  US10/735,725
• Publication Number:
  US 20040125062A1
• Time in Patent Office: 3,584 Days
• Field of Search: 345/87, 345/89, 345/90, 345/94, 345/95, 345/98, 345/99, 345/100, 345/102, 349/61, 349/62, 349/63, 349/66, 349/68, 349/69, 349/70, 349/71
• US Class Current: 345/52
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• 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 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display apparatus is able to display high quality motion pictures with less after-image when displaying motion pictures and with less fuzzy images without making the response speed of the liquid crystal too fast. The display data emphasized excessively more than a changed value is written into the pixel having any change detected by comparison with the previous display data and its value is made to change excessively more than the value corresponding to its original display data, and then, according to the optical response of the liquid crystal, the lighting time and the lighting period of the light source are controlled for the individual areas of the illumination unit having plural areas.

Claims

1. A liquid crystal display apparatus comprising:

a pair of substrates, at least one of which is transparent;

a liquid crystal layer disposed between the pair of substrates;

a plurality of groups of electrodes disposed on at least one of the pair of substrates for applying an electric field to the liquid crystal layer;

a liquid crystal display part having a plurality of active elements connected to the electrodes;

a drive means, supplied with display data from a means for supplying display data, the drive means for driving individual pixels of the liquid crystal display part by applying a voltage corresponding to the display data to the individual pixels, the drive means including a data emphasis means for comparing new display data supplied for a current display frame from the means for supplying display data, with previous display data supplied for a previous display frame from the means for supplying display data, and for emphasizing the new display data to effect an overshot drive to drive the liquid crystal display portion so that a transmittance level exceeds a designated transmittance level within a first frame period and is maintained to exceed the designated transmittance level within a second frame period subsequent to the first frame period, in response to a difference detected between the previous display data and new display data as a result of the comparison;

an illumination panel unit divided into a plurality of illumination panel portions, with each illumination panel portion having a light source providing illumination to the liquid crystal display part; and

an illumination control means, responsive to the overshot drive resulting in the transmittance level exceeding the designated transmittance level, for dynamically controlling an illumination start time and an illumination “

on”

time of the light source of individual said illumination panel portions, respectively, so that a time integral value of transmittance for an overshoot-frame, is equal to a time integral value of transmittance for a non-overshoot frame in which the transmission reaches and stays in a stable state at the designated transmittance level.

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

wherein when said difference is detected in the display data by the comparison, the data emphasis means emphasizes and converts the new display data so as to increase the difference, and modifies a response of a corresponding pixel provided in the individual pixels of the liquid crystal display part so as to be larger than a value corresponding to an original value of the new display data;

and

wherein the illumination control means controls the illumination start time and the illumination “

on”

time of a corresponding one of light sources of the illumination panel portions of the illumination panel unit so that a time integral value of an amount of light passing through the corresponding pixel while a display characteristic is changing is equal to a time integral value of an amount of light passing through the corresponding pixel while the display characteristic is stable.

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

wherein when said difference is detected in the display data by the comparison, the data emphasis means emphasizes and converts the new display data so as to increase the difference, and modifies a response of a corresponding pixel of the liquid crystal display part so as to be larger than a value corresponding to an original value of the new display data;

and

wherein the illumination control means controls the illumination start time and the illumination “

on”

time of a corresponding one of light sources of the illumination panel portions of the illumination panel unit so that visual sensation values with respect to light passing through the corresponding pixel in the course of response and after response are identical to each other.

4. The liquid crystal display apparatus according to claim 1, wherein the illumination start time and the illumination “

on”

time of light sources of the illumination panel portions of the illumination panel unit are made to be equal to average values of values for all the display data dependent on the individual display data according to the response of the liquid crystal display part after the emphasizing.

5. The liquid crystal display apparatus according to claim 2, wherein the illumination start time and the illumination “

on”

time of the light sources of the illumination panel portions of the illumination panel unit are made to be equal to average values of values for all the display data dependent on the individual display data according to the response of the liquid crystal display part after the emphasizing.

6. The liquid crystal display apparatus according to claim 3, wherein the illumination start time and the illumination “

on”

time of the light sources of the illumination panel portions of the illumination panel unit are made to be equal to average values of values for all the display data dependent on the individual display data according to the response of the liquid crystal display part after the emphasizing.

7. The liquid crystal display apparatus according to claim 1, wherein the illumination start time and the illumination “

on”

time of light sources of the illumination panel portions of the illumination panel unit are changed adaptively and determined so as to be average values weighted with a number of display data to be displayed at an area among values dependent on the individual display data according to the response of the liquid crystal display part after data emphasis and conversion.

8. The liquid crystal display apparatus according to claim 2, wherein the illumination start time and the illumination “

on”

time of the light sources of the illumination panel portions of the illumination panel unit are changed adaptively and determined so as to be average values weighted with a number of display data to be displayed at an area among values dependent on the individual display data according to the response of the liquid crystal display part after data emphasis and conversion.

9. The liquid crystal display apparatus according to claim 3, wherein the illumination start time and the illumination “

on”

time of light sources of the illumination panel portions of the illumination panel unit are changed adaptively and determined so as to be average values weighted with a number of display data to be displayed at an area among values dependent on the individual display data according to the response of the liquid crystal display part after data emphasis and conversion.

10. The liquid crystal display apparatus according to claim 1, wherein the light source includes a sheet-type light emitting element.

11. A liquid crystal display apparatus comprising:

a pair of substrates, at least one of which is transparent;

a liquid crystal layer disposed between the pair of substrates;

a plurality of groups of electrodes disposed on at least one of the pair of substrates for applying an electric field to the liquid crystal layer;

a liquid crystal display part having a plurality of active elements connected to the electrodes;

a drive means, supplied with display data from a means for supplying display data, the drive means for driving individual pixels of the liquid crystal display part by applying a voltage corresponding to the display data to the individual pixels, the drive means including a data emphasis means for comparing new display data supplied for a current display frame from the means for supplying display data, with previous display data supplied for a previous display frame from the means for supplying display data, and for emphasizing the new display data to effect an overshot drive to drive the liquid crystal display portion so that a transmittance level exceeds a designated transmittance level within a first frame period and is maintained to exceed the designated transmittance level within a second frame period subsequent to the first frame period, in response to a difference detected between the previous display data and new display data as a result of the comparison;

an illumination panel unit divided into a plurality of illumination panel portions, with each illumination panel portion having a light source providing illumination to the liquid crystal display part; and

an illumination control means, responsive to the overshot drive resulting in the transmittance level exceeding the designated transmittance level, for dynamically controlling an illumination start time and an illumination “

on”

time of the light source of individual said illumination panel portions, respectively, so that a time integral value of transmittance for a time period occupied by the illumination “

on”

time in an overshoot-frame period is equal to a time integral value of transmittance for a time period occupied by the illumination “

on”

time in a frame period in which transmittance is in a stable state.