KR20110064343A - Method for measuring ghosting of electrophoretic display apparatus - Google Patents

Method for measuring ghosting of electrophoretic display apparatus Download PDF

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Publication number
KR20110064343A
KR20110064343A KR1020090120889A KR20090120889A KR20110064343A KR 20110064343 A KR20110064343 A KR 20110064343A KR 1020090120889 A KR1020090120889 A KR 1020090120889A KR 20090120889 A KR20090120889 A KR 20090120889A KR 20110064343 A KR20110064343 A KR 20110064343A
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South Korea
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sub
regions
ghosting
electrophoretic display
region
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KR1020090120889A
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Korean (ko)
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박정욱
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엘지디스플레이 주식회사
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Priority to KR1020090120889A priority Critical patent/KR20110064343A/en
Publication of KR20110064343A publication Critical patent/KR20110064343A/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
    • G02F1/166—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect
    • G02F1/167—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect by electrophoresis
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/30—Gray scale
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/006—Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

Abstract

PURPOSE: A ghosting measuring method of an electrophoresis display device is provided to supply an object standard for evaluating a display device at a ghosting surface by quantifying the ghosting phenomena of the electrophoresis display device. CONSTITUTION: A ghosting measuring method of an electrophoresis display device includes as follows; a step of displaying a first etching on a test area of an electrophoresis display panel(S1); a step of displaying a third etching which is different from a second etching and displaying the second etching to the first area(S2); a step of displaying the first etching to the test area(S3); a step of measuring reflective area of the first and the second area(S4); a step of producing the difference of the reflective area of the first area and the reflective area of the second area for obtaining a ghosting value corresponding to the first etching.

Description

Measuring method for ghosting of electrophoretic display device {Method for Measuring Ghosting of Electrophoretic Display Apparatus}

The present invention relates to a ghosting measurement method of an electrophoretic display device.

The electrophoretic display is one of flat panel displays used in the manufacture of e-books and includes an electrophoretic film and a TFT substrate for driving the electrophoretic film pixel by pixel.

In the case of an electrophoretic display, an electrophoretic dispersion is positioned between two electrodes that face each other. In the microcapsule method, a plurality of microcapsules storing the electrophoretic dispersion therein form a layer between the two electrodes. In the microcup method, the electrophoretic dispersion is partitioned pixel by pixel. The colored charge particles contained in the electrophoretic dispersion are moved to the electrodes of opposite polarity by electrophoresis by the voltage applied to the two electrodes, thereby displaying an image.

The electrophoretic display device has bistable stability, so that the original image can be preserved for a long time even if the applied voltage is removed. Due to this bistable property, when displaying a new image, a phenomenon in which the previous image remains, a so-called ghosting phenomenon occurs.

An aspect of the present invention is to provide a method for measuring ghosting of an electrophoretic display, which can provide an objective criterion for evaluating the display in terms of ghosting by quantifying the ghosting phenomenon of the electrophoretic display.

In addition to the aspects of the present invention mentioned above, other features and advantages of the present invention will be described below, or will be clearly understood by those skilled in the art from such description and description.

In addition, other features and advantages of the present invention may be newly understood through practice of the present invention.

According to an aspect of the present invention as described above, displaying a first gray scale in a test area of an electrophoretic display panel, wherein the test area includes first and second areas; Displaying a second gray scale in the first region and displaying a third gray scale different from the second gray scale in the second region; Subsequently displaying the first gray level in the test area; Thereafter, measuring reflectances of the first and second regions, respectively; And calculating a difference between the reflectance of the first region and the reflectance of the second region to obtain a ghosting value corresponding to the first grayscale. A measurement method is provided.

The test area may be an entire area of the electrophoretic display panel.

The first and second regions may include a plurality of first sub regions and a plurality of second sub regions, respectively. In this case, the reflectance of the first region is an average value of reflectances of the plurality of first sub-regions, and the reflectance of the second region is an average value of reflectances of the plurality of second sub-regions.

The first and second sub-regions may have a polygonal shape, in particular a quadrangular shape, and may optionally have a circular shape.

The first and second sub-regions may be alternately arranged in the vertical direction and the horizontal direction.

The number of the first sub-regions may be the same as the number of the second sub-regions.

The second and third gray levels may be in two extreme optical states, for example black and white.

The ghosting values for each grayscale can be obtained by measuring the ghosting of the electrophoretic display device while changing the first grayscale.

General description of the present invention as described above is only for illustrating or illustrating the present invention, it does not limit the scope of the present invention.

According to the present invention, it is possible to provide an objective criterion for evaluating the display device in terms of ghosting by quantifying the ghosting phenomenon of the electrophoretic display device.

Hereinafter, exemplary embodiments of a ghosting measuring method of an electrophoretic display device according to the present invention will be described in detail with reference to the accompanying drawings.

The technical idea of the present invention may be applied to all electrophoretic display devices regardless of color implementation. Hereinafter, the present invention will be described by taking a mono type electrophoretic display device that implements only black and white for convenience of description. . That is, the technical idea of the present invention disclosed below, as well as an electrophoretic display device further including a color filter, of the electrophoretic display device in which the charged particles in the electrophoretic dispersion are colored red, blue, green or white. The same may be applied to the case.

In addition, the technical idea of the present invention may be equally applied to both a microcapsule type and a microcup type electrophoretic display device, but hereinafter, a microcapsule type electrophoretic display is provided for convenience of description. The present invention will be described by taking an apparatus as an example.

The term "Gray Scale" used in describing the present invention refers to two extreme optical states and different displayable optical states therebetween. The two extreme optical states here do not mean only white and black. For example, two extreme optical states can be white and blue. In this case, the halftones between them will be light blue.

1 is a block diagram schematically illustrating an electrophoretic display device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, an electrophoretic display device according to an exemplary embodiment includes an electrophoretic display panel 10, a data driver 20, a gate driver 30, and a timing controller 40. do.

In the electrophoretic display panel 10, the data lines D1 to Dm and the gate lines G1 to Gn cross each other, and m × n pixels 11 are arranged in a matrix type due to the cross structure. Switching elements SW are formed in regions where the data lines D1 to Dm and the gate lines G1 to Gn cross each other. The switching device SW may be a thin film transistor. Hereinafter, the switching device SW will be described using a thin film transistor as an example. Each thin film transistor SW has a gate electrode, a source electrode, and a drain electrode. The gate electrode is connected to one of the gate lines G1 to Gn, the source electrode is connected to one of the data lines D1 to Dm, and the drain electrode is connected to the pixel electrode of the corresponding pixel 11.

When the scan pulse is supplied to the switching elements SW connected to the corresponding line through the gate lines G1 to Gn, the thin film transistors SW are turned on in response to the scan pulse so that the data is turned on. The data voltage supplied through the lines D1 to Dm is applied to the pixel electrodes of the corresponding pixels 11.

The pixel electrode forms the electrophoretic capacitor C ep together with the common electrode and simultaneously forms the storage capacitor C st together with the storage electrode.

An electrophoretic dispersion containing colored charged particles exists between the pixel electrode and the common electrode. Therefore, when the data voltage and the common voltage V com are respectively applied to these two electrodes, the colored charged particles included in the electrophoretic dispersion are moved to the electrodes of opposite polarities by electrophoresis, respectively. An image is displayed on the pixel 11.

On the other hand, when the gate voltage applied to the gate electrode is turned off, a so-called "kickback voltage" is caused by a parasitic capacitance formed in the thin film transistor. The kickback voltage deteriorates the pixel voltage holding characteristic of the electrophoretic display, leading to a decrease in reflectance and contrast ratio. The storage capacitor C st is to minimize image degradation caused by the kickback voltage.

The data driver 20 is also referred to as a source driver, and supplies the data voltages corresponding to the grayscales to be displayed to the data lines D1 to Dm under the control of the timing controller 40.

The gate driver 30, also referred to as a scan driver, supplies a scan pulse to the gate lines G1 to Gn for controlling the switching operation of the thin film transistors SW under the control of the timing controller 40.

The timing controller 40 receives the vertical / horizontal synchronization signal Vsync / Hsync, the clock signal CLK, etc. from an external graphic controller (not shown) to adjust the operation timing of the data driver 20 and the gate driver 30. Generates a control signal for controlling. In addition, the timing controller 40 receives the image data from the graphic controller, and determines the driving waveform of the data voltage corresponding to the received image data by using a lookup table, a frame counter, and the like. The digital data corresponding to the driving waveform of is transmitted to the data driver 20.

Hereinafter, a ghosting measuring method of an electrophoretic display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 2 to 5.

2 is a flow chart briefly showing the ghosting measuring method of the present invention.

As shown in the flowchart of FIG. 2, the ghosting measuring method of the present invention includes displaying a first gray scale in a test region including a first region and a second region (S1), and applying a second gray scale to the first region. Displaying and displaying a third gray scale in the second region (S2), displaying the first gray scale in the test region (S3), and measuring reflectances of the first and second regions, respectively (S4). Calculating a difference between the reflectance of the first region and the reflectance of the second region (S5).

3 to 5 are screens displayed on the electrophoretic display panel 10 when the ghosting measuring method of the present invention is performed.

As shown in FIG. 3, the test area 100 according to the exemplary embodiment of the present invention is the entire electrophoretic display panel 10 and displays the first gray level on the entire test area 100 (S1). The first gradation is any gradation that the electrophoretic display can display.

Although the test area 100 is preferably the entire electrophoretic display panel 10 in that the ghosting phenomenon can be measured for the entire area of the electrophoretic display panel 10, the test area 100 is the electrophoretic display. If it is distributed uniformly throughout the panel 10, it may not be the whole panel 10.

Subsequently, a second gray scale is displayed in the first region and a third gray scale is displayed in the second region according to a test pattern for dividing the test region 100 into first and second regions (S2).

According to an embodiment of the present invention shown in FIG. 4, the first region includes two first sub regions 110, and the second region includes two second sub regions 120. The first and second sub-regions 110 and 120 each have a rectangular shape and are arranged in a 2 × 2 lattice structure. That is, the first and second sub regions 110 and 120 having a rectangular shape are alternately arranged in the vertical direction and the horizontal direction.

The second gray level displayed in the first sub-areas 110 and the third gray level displayed in the second sub-areas 120 are required to be different from each other. If only this requirement is satisfied, each of the second and third gray levels may be any gray level that the electrophoretic display device can display. However, the second and third grayscales may be two extreme optical states, for example, white and black, in that a greater gray level difference between the second and third grayscales may improve the accuracy of the ghosting measurement value. .

Subsequently, the first gray scale displayed in the first step S1 is displayed again on the entire test area 100 (S3).

In the case of a perfect electrophoretic display panel in which ghosting does not occur, the first gray level is displayed in both the first and second sub-regions 110 and 220, and there is no visual distinction between them. In the generated electrophoretic display panel 10, afterimages of the test patterns remain in the test area 100 as illustrated in FIG. 5. That is, due to the difference in reflectance between the first and second sub-regions 110 and 120, they are visually distinguished from each other.

Subsequently, reflectances of the first and second regions are respectively measured (S4).

According to an embodiment of the present invention, since the first and second regions each include a plurality of first sub-regions 110 and a plurality of second sub-regions 120, reflectances of the first region are provided. May be obtained by measuring reflectances of the plurality of first sub-regions 110 and calculating average values thereof. Similarly, the reflectance of the second region may be obtained by measuring the reflectances of the plurality of second sub-regions 120 and calculating their average values, respectively.

Subsequently, a difference in reflectance between the first and second regions is calculated (S5).

The difference in reflectance between the first and second regions indicates the degree of ghosting. The more severe the ghosting phenomenon, the greater the difference in reflectance between the first and second regions. Accordingly, the difference in reflectance between the first and second regions may be regarded as a value indicating a degree of occurrence of a ghosting phenomenon (hereinafter referred to as a "ghosting value"). The ghosting value corresponding to the first gray level may be obtained by calculating a difference between reflectances of the first and second regions.

By comparing the ghosting value obtained by the above method with a predetermined reference value, the electrophoretic display may be objectively evaluated in terms of ghosting.

6 illustrates a test pattern according to another embodiment of the present invention.

According to the test pattern illustrated in FIG. 6, the entire electrophoretic display panel 10 is set as the test area 100, and the first area of the test area 100 includes eight first sub-areas 110. The second region includes eight second sub regions 120. That is, the number of the first sub-regions 110 and the number of the second sub-regions 120 are the same.

The first and second sub-regions 110 and 120 each have a rectangular shape and are arranged in a 4 × 4 lattice structure. That is, the first and second sub regions 110 and 120 having a quadrangular shape are alternately arranged in the vertical direction and the horizontal direction.

7 shows a test pattern according to another embodiment of the present invention.

According to the test pattern illustrated in FIG. 7, only a part of the electrophoretic display panel 10 is set as the test area 100, and the first area of the test area 100 includes eight first sub areas 110. The second area includes eight second sub areas 120. That is, the number of the first sub-regions 110 and the number of the second sub-regions 120 are the same.

The first and second sub-regions 110 and 120 each have a circular shape and are alternately arranged in a vertical direction and a horizontal direction.

As illustrated above, the first and second sub-regions 110, 120 of the present invention may have the shape of a polygon, in particular a quadrangle, as shown in FIGS. 4 and 6, optionally shown in FIG. 7. It may have a circular shape as shown.

The embodiments of the present invention described above are for illustrative purposes only, and the inventive concept does not limit the number and shape of the first and second sub-regions 110 and 120. The first and second sub-regions 110 and 120 of the present invention may have any shape and be arranged in a lattice structure of M × N, where M and N are any integer.

The electrophoretic display may be objectively evaluated in terms of ghosting by comparing a ghosting value corresponding to the first grayscale obtained by the method described above with a predetermined reference value.

Optionally, the ghosting values for each gradation can be obtained by measuring the ghosting of the electrophoretic display device while changing the first gradation to all gradable gradations. The electrophoretic display device can be evaluated in terms of ghosting by comparing the average value of the ghosting values obtained for each gray level with a predetermined reference value.

It is to be understood that the embodiments of the present invention described above are merely intended to illustrate or describe the present invention, and to provide a more detailed description of the invention of the claims. It will be apparent to those skilled in the art that various changes and modifications of the embodiments can be made without departing from the spirit and scope of the invention. Accordingly, the invention includes all changes and modifications within the scope of the invention as set forth in the claims and their equivalents.

The accompanying drawings are included to assist in understanding the present invention and to form a part of the specification, to illustrate embodiments of the present invention, and to explain the principles of the present invention together with the detailed description of the invention.

1 is a block diagram schematically showing an electrophoretic display device in which ghosting is measured by the method of the present invention,

2 is a flow chart briefly showing the ghosting measuring method of the present invention,

3 to 5 are screens displayed on the electrophoretic display panel when the ghosting measuring method of the present invention is performed,

6 shows a test pattern according to another embodiment of the present invention,

7 shows a test pattern according to another embodiment of the present invention.

<Short description of drawing symbols>

10: electrophoretic display panel 100: test area

110: first sub area 120: second sub area

Claims (10)

Displaying a first gray level in a test area of the electrophoretic display panel, wherein the test area includes first and second areas; Displaying a second gray scale in the first region and displaying a third gray scale different from the second gray scale in the second region; Subsequently displaying the first gray level in the test area; Thereafter, measuring reflectances of the first and second regions, respectively; And And calculating a difference between the reflectance of the first region and the reflectance of the second region to obtain a ghosting value corresponding to the first grayscale. Way. The method of claim 1, And the test area is an entire area of the electrophoretic display panel. The method of claim 1, The first region includes a plurality of first sub regions, The second region includes a plurality of second sub regions, The reflectance of the first region is an average value of reflectances of the plurality of first sub-regions, And a reflectance of the second area is an average value of reflectances of the plurality of second sub-areas. The method of claim 3, wherein The first and second sub-regions have a polygonal shape ghosting measurement method of the electrophoretic display device. The method of claim 4, wherein The first and second sub-regions have a rectangular shape ghosting measurement method of the electrophoretic display device. The method of claim 3, wherein The first and second sub-regions have a circular shape ghosting measuring method of the electrophoretic display device. The method according to any one of claims 3 to 6, And the first and second sub-areas alternately arranged in a vertical direction and a horizontal direction. The method of claim 7, wherein And the number of the first sub-regions is the same as the number of the second sub-regions. The method of claim 1, The second gradation is white, And the third gray level is black. The method of claim 1, And obtaining ghosting values for each gradation by repeating the steps of claim 1 while changing the first gradation.
KR1020090120889A 2009-12-08 2009-12-08 Method for measuring ghosting of electrophoretic display apparatus KR20110064343A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110910841A (en) * 2019-12-16 2020-03-24 电子科技大学中山学院 System and method for reducing ghost image of electrophoretic electronic paper

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110910841A (en) * 2019-12-16 2020-03-24 电子科技大学中山学院 System and method for reducing ghost image of electrophoretic electronic paper

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