Liquid Crystal Display Device and Driving Method Thereof

• US 20080180385A1
• Filed: 11/29/2007
• Published: 07/31/2008
• Est. Priority Date: 12/05/2006
• Status: Abandoned Application

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kimura, Hajime, Yoshida, Yasunori
• Application Number:
  US11/947,525
• Publication Number:
  US 20080180385A1
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2300/0809 Several active elements per pixel in active matrix panels
• CPC Class Codes: G09G 2300/0819 used for counteracting undesired variations, e.g. feedback or autozeroing
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0852 being a dynamic memory with more than one capacitor
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2300/088 using a non-linear two-terminal element
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• 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 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• 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 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 2320/041 : Temperature compensation
• CPC Class Codes: G09G 2320/043 : Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0613 : The adjustment depending on the type of the information to be displayed
• CPC Class Codes: G09G 2320/0646 : Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/106 : Determination of movement vectors or equivalent parameters within the image
• CPC Class Codes: G09G 2330/021 : Power management, e.g. power saving
• 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 2360/144 : the light being ambient light
• CPC Class Codes: G09G 2360/16 : Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/20 : for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2018 : by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2022 : using sub-frames
• CPC Class Codes: G09G 3/2074 : using sub-pixels
• CPC Class Codes: G09G 3/2081 : with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/22 : using controlled light sources
• CPC Class Codes: G09G 3/3258 : with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3406 : Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3413 : Details of control of colour illumination sources
• 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 3/3607 : for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels display of colours in flat matrix panels other than liquid crystal displays G09G3/2003; grey scales specific for television H04N3/127
• CPC Class Codes: G09G 3/3648 : using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3659 : the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes
• CPC Class Codes: G09G 3/3677 : suitable for active matrices only
• CPC Class Codes: G09G 3/3688 : suitable for active matrices only
• CPC Class Codes: H04M 1/0214 : Foldable telephones, i.e. with body parts pivoting to an open position around an axis parallel to the plane they define in closed position combined with translation movement H04M1/0235
• CPC Class Codes: H04M 1/0266 : for a display module assembly
• CPC Class Codes: H04M 2250/16 : including more than one display unit
• CPC Class Codes: H04W 52/0251 : using monitoring of local events, e.g. events related to user activity
• CPC Class Codes: Y02D 30/70 : in wireless communication networks

Abstract

To provide a hold-type display device without a problem of motion blur and a driving method thereof. The length of a period for displaying a blanking image in one frame period is controlled in accordance with a control parameter showing the degree of motion blur, and the level of a signal supplied to a display element is changed in accordance with the length of the period for displaying the blanking image. Accordingly, the hold-type display device without a problem of motion blur and the driving method thereof can be provided.

Claims

1. A driving method of a liquid crystal display device in which an image is displayed by applying a signal voltage in accordance with an image signal to a liquid crystal element,

the driving method comprising:

applying a first voltage to the liquid crystal element in a first subframe period of one frame period; and

applying a second voltage at which the liquid crystal element performs black display in a second subframe period of the one frame period,

wherein a level of the first voltage is determined in accordance with a difference between the second voltage and the signal voltage, and a length of the first subframe period.

2. A driving method of a liquid crystal display device according to claim 1, wherein the larger the difference between the first voltage and the signal voltage is, the shorter the length of the subframe period is.

3. A driving method of a liquid crystal display device comprising a backlight, in which an image is displayed by applying a signal voltage in accordance with an image signal to a liquid crystal element,

the driving method comprising:

applying an initialization voltage to the liquid crystal element; and

applying a first voltage to the liquid crystal element in one frame period right after applying the initialization voltage,

wherein a level of the first voltage is determined in accordance with a difference between the initialization voltage and the signal voltage, and a length of a backlight lighting period in the one frame period.

4. A driving method of a liquid crystal display device according to claim 3, wherein the larger the difference between the initialization voltage and the signal voltage is, the shorter the length of the backlight lighting period is.

5. A driving method of a liquid crystal display device comprising a backlight, in which an image is displayed by applying a signal voltage in accordance with an image signal to a liquid crystal element,

wherein the backlight is divided into the plurality of light-emitting regions,

the driving method comprising:

while sequentially scanning the plurality of light-emitting regions,

applying an initialization voltage to the liquid crystal element; and

applying a first voltage to the liquid crystal element in one frame period right after applying the initialization voltage,

wherein a level of the first voltage is determined in accordance with a difference between the initialization voltage and the signal voltage, and a length of a lighting period of each of the plurality of light-emitting regions in the one frame period.

6. A driving method of a liquid crystal display device according to claim 5, wherein the larger the difference between the initialization voltage and the signal voltage is, the shorter the length of the backlight lighting period is.

7. A driving method of a liquid crystal display device comprising a backlight, in which an image is displayed by applying a signal voltage in accordance with an image signal to a liquid crystal element,

the driving method comprising:

applying an initialization voltage to the liquid crystal element;

applying a first voltage to the liquid crystal element in one frame period right after applying the initialization voltage; and

applying a second voltage at which the liquid crystal element performs black display in the second subframe period,

wherein a level of the first voltage is determined in accordance with a difference between the second voltage and the signal voltage, a length of the backlight lighting period in the one frame period, and a length of the first subframe period.

8. A driving method of a liquid crystal display device comprising a backlight, in which an image is displayed by applying a signal voltage in accordance with an image signal to a liquid crystal element,

wherein the backlight is divided into a plurality of light-emitting regions,

the driving method comprising:

while sequentially scanning a plurality of light-emitting regions,

applying an initialization voltage to the liquid crystal element;

applying a first voltage to the liquid crystal element in one frame period right after applying the initialization voltage; and

applying a second voltage at which the liquid crystal element performs black display in the second subframe period,

wherein a level of the first voltage is determined in accordance with a difference between the second voltage and the signal voltage, a length of a lighting period of each of the plurality of light-emitting regions, and a length of the first subframe period.

9. A liquid crystal display device comprising:

a liquid crystal element,

wherein an image is configured to be displayed by applying a signal voltage in accordance with an image signal to the liquid crystal element,

wherein a level of a first voltage which is applied to the liquid crystal element in a first subframe period of one frame period is determined in accordance with a difference between a second voltage which is applied to the liquid crystal element in a second subframe period of the one frame period and the signal voltage, and a length of the first subframe period, and

wherein the second voltage is voltage at which the liquid crystal element performs black display.

10. A liquid crystal display device according to claim 9, wherein the larger the difference between the first voltage and the signal voltage is, the shorter the length of the subframe period is.

11. A liquid crystal display device, comprising:

a liquid crystal element; and

a backlight,

wherein an image is configured to be displayed by applying a signal voltage in accordance with an image signal to the liquid crystal element, and

wherein a level of a first voltage which is applied to the liquid crystal element in one frame period is determined in accordance with a difference between an initialization voltage which is applied to the liquid crystal element right before the one frame period and the signal voltage, and a length of a backlight lighting period in the one frame period.

12. A liquid crystal display device according to claim 11, wherein the larger the difference between the initialization voltage and the signal voltage is, the shorter the length of the backlight lighting period is.

13. A liquid crystal display device, comprising:

a liquid crystal element; and

a backlight,

wherein an image is configured to be displayed by applying a signal voltage in accordance with an image signal to a liquid crystal element,

wherein the backlight is divided into a plurality of light-emitting regions and is configured to be sequentially scanned to emit light, and

wherein a level of a first voltage which is applied to the liquid crystal element in one frame period is determined in accordance with a difference between an initialization voltage which is applied to the liquid crystal element right before the one frame period and the signal voltage, and a length of the lighting period of each of the plurality of light-emitting regions in the one frame period.

14. A liquid crystal display device according to claim 13, wherein the larger the difference between the initialization voltage and the signal voltage is, the shorter the length of the backlight lighting period is.

15. A liquid crystal display device, comprising:

a liquid crystal element; and

a backlight,

wherein an image is configured to be displayed by applying a signal voltage in accordance with an image signal to the liquid crystal element,

wherein a level of a first voltage which is applied to the liquid crystal element in a first subframe period of one frame period is determined in accordance with a difference between a second voltage which is applied to the liquid crystal element in a second subframe period of the one frame period and the signal voltage, and a length of a backlight lighting period in the one frame period, and

wherein the second voltage which is applied to the liquid crystal element in the second subframe period is voltage at which the liquid crystal element performs black display.

16. A liquid crystal display device, comprising:

a liquid crystal element; and

a backlight,

wherein an image is configured to displayed by applying a signal voltage in accordance with an image signal to the liquid crystal element,

wherein the backlight is divided into a plurality of light-emitting regions and is configured to be sequentially scanned to emit light,

wherein a level of a first voltage which is applied to the liquid crystal element in a first subframe period of one frame period is determined in accordance with a difference between a second voltage which is applied to the liquid crystal element in a second subframe period and the signal voltage, a length of the lighting period of each of the plurality of light-emitting regions in the one frame period, and a length of the first subframe period; and

wherein the second voltage is voltage at which a liquid crystal element performs black display.