KR101076484B1 - Apparatus for amending driving signal of electrophoretic display and Method thereof - Google Patents

Abstract

The present invention discloses a drive signal correction apparatus and method thereof for an electrophoretic display. The drive signal correction apparatus of the electrophoretic display according to the present invention, the voltage driver for applying a drive signal to the upper and lower electrodes of the electrophoretic display; A current sensing unit sensing a driving current flowing between the upper and lower electrodes; A memory unit for storing a look-up table that defines a driving signal correction factor according to the magnitude of the driving current; And a control unit configured to correct a driving signal applied to the upper and lower electrodes by reading a driving signal correction factor corresponding to the sensed current from the look-up table and then controlling the voltage driving unit according to the driving signal correction factor. It is characterized by including.

According to the present invention, it is possible to correct the deterioration of the display performance due to the change in the ambient temperature and the long time use, thereby enabling a more accurate grayscale representation. In addition, there is no need to add a separate sensor for sensing temperature, which can reduce costs and reduce the volume of the display.

Electrophoretic display, current, temperature, drive signal, feedback

Description

Apparatus for amending driving signal of electrophoretic display and Method

The present invention relates to an electrophoretic display, and more particularly, to an apparatus and method for correcting a driving signal of an electrophoretic display, which can more accurately express grayscales by compensating the influence of external factors when driving an electrophoretic display.

In recent years, due to the necessity of large-scale conversion to the information transmission and sharing method corresponding to the information society, technology development of e-paper with excellent flexibility, portability, and light weight has been accelerated. It is entering the commercial development stage. Electronic paper is cheaper than conventional flat panel display panels and does not require backlighting or continuous recharging like liquid crystal displays, so it can be driven with very little energy, leading to energy efficiency. In addition, electronic paper is very sharp like conventional papers and inks, has a wide viewing angle, and has its own memory effect, so that an image can be displayed for a long time without large power consumption.

These advantages allow electronic paper to represent moving illustrations while retaining some of the traditional features of paper, making it a huge field for electronic books, self-renewing newspapers, reusable paper displays for mobile phones, disposable TV screens and electronic wallpaper. It has a huge potential market.

The technical approaches to the electronic paper implementation include liquid crystal, organic EL, reflective display, twistball, electrochromic, mechanical reflective, and electrophoresis. The most notable electronic paper implementation technology is an electrophoretic display using an electrophoretic phenomenon.

1 is a cross-sectional view schematically showing one pixel in a typical electrophoretic display.

The general electrophoretic display 10 includes upper and lower substrates 11 and 12 facing each other at predetermined intervals and made of a transparent material, and upper and lower electrodes formed on inner surfaces of the upper and lower substrates 11 and 12, respectively. (21, 22), an insulating film (30) formed on inner surfaces of the upper and lower electrodes (21, 22), and a partition wall that separates each pixel and supports the upper and lower substrates (11, 12) ( 70, the fluid 40 filled between the upper and lower substrates 11 and 12, and the white and black particles 50 and 60 charged with different charges, and the upper and lower electrodes 21 and 22, respectively. It includes a driver 80 for applying a signal.

The electrophoretic display 10 has white and black particles 50 and 60 charged with different charges according to the direction of the electric field formed in the fluid 40 by driving signals applied to the upper and lower electrodes 21 and 22. An image or a character may be expressed by using a phenomenon of moving between the upper and lower electrodes 21 and 22. When the negative and positive potentials are repeatedly applied to the upper and lower electrodes 21 and 22 by controlling the waveform of the driving signal, the white and black particles 50 and 60 may move at high speed between the upper and lower electrodes 21 and 22. Since it is reciprocated, the grayscale may be represented in the electrophoretic display 10. In addition, if the white and black particles 50 and 60 stay on the upper and lower electrodes 21 and 22, the brightness of the gray scale may be adjusted.

However, the movement speeds of the white and black particles 50 and 60 are affected by the resistance of the fluid 40, the strength of the electric field, the dielectric properties of the charged white and black particles 50 and 60 and the fluid 40, and the like. Receives. In addition, the influence of the external environment such as temperature and the deterioration of the fluid 70 due to prolonged use affects the viscosity of the fluid 70, which hinders the movement of the white and black particles 50 and 60 to slow the movement speed. Cause problems. This problem is a factor that reduces the accuracy of grayscale representation. As a method for correcting such a problem, conventionally, a method of increasing the accuracy of gray scale by measuring an external temperature and adjusting driving signals applied to the upper and lower electrodes 21 and 22 based on the measured temperature is used. However, since this method requires an expensive temperature sensor that senses the external temperature and measures the external temperature rather than the temperature of the fluid 40, the actual temperature and error of the fluid 40 may occur, so gray scale may be reduced. There is a limit in expressing correctly.

The present invention was devised to solve the above problems of the prior art, and a device and method for compensating a driving signal of an electrophoretic display which can accurately correct the effect of the temperature around the electrophoretic display to express accurate grayscale. The purpose is to provide.

In order to achieve the above object, a driving signal correction apparatus for an electrophoretic display according to the present invention includes a voltage driver for applying a driving signal to upper and lower electrodes of an electrophoretic display; A current sensing unit sensing a driving current flowing between the upper and lower electrodes; A memory unit for storing a look-up table that defines a driving signal correction factor according to the magnitude of the driving current; And a control unit configured to correct a driving signal applied to the upper and lower electrodes by reading a driving signal correction factor corresponding to the sensed current from the look-up table and then controlling the voltage driving unit according to the driving signal correction factor. It is characterized by including.

Preferably, the drive signal correction factor is composed of data indicating the degree of correction for the drive signal.

According to an aspect of the present invention, the driving signal correction factor is data representing a width of increase and decrease with respect to the voltage magnitude of the driving signal, and the controller controls the voltage driver according to the driving signal correction factor and applies it to the upper and lower electrodes. The drive signal is corrected by adjusting the voltage magnitude of the drive signal.

According to another aspect of the present invention, the driving signal correction factor is data representing a width of increase and decrease with respect to the holding time of the driving signal, and the controller controls the voltage driver according to the driving signal correction factor and applies it to the upper and lower electrodes. The drive signal is corrected by adjusting the application time of the drive signal. At this time, the controller keeps the duty ratio of the drive signal constant.

Preferably, the controller periodically receives the current value from the current sensing unit to correct the driving signal by the feedback control.

According to an aspect of the present invention, there is provided a method of correcting a driving signal of an electrophoretic display, the method comprising: (a) constructing a look-up table defining a driving signal correction factor according to a driving current magnitude of the electrophoretic display; (b) applying a drive signal to upper and lower electrodes of the electrophoretic display; (c) sensing a driving current flowing between the upper and lower electrodes; (d) reading a drive signal correction factor corresponding to the sensed drive current from the look-up table; And (e) correcting a driving signal applied to the upper and lower electrodes according to the driving signal correction factor.

According to another aspect of the present invention, there is provided a computer-readable recording medium in which the above-described drive signal correction method of an electrophoretic display is programmed.

According to the present invention, by providing a drive signal correction device that can sense the drive current of the electrophoretic display and correct the drive signal of the electrophoretic display by using it, to compensate for the degradation of display performance due to changes in ambient temperature and long-term use This allows more accurate grayscale representation. In addition, there is no need to add a separate sensor for sensing temperature, which can reduce costs and reduce the volume of the display.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

2 is a block diagram showing the configuration of a drive signal correction apparatus of an electrophoretic display according to a preferred embodiment of the present invention.

The driving signal correction apparatus 200 of the electrophoretic display according to the present invention is connected to the electrophoretic display pixel 100 and corrects the driving signal applied to the electrophoretic display pixel 100.

The electrophoretic display pixel 100 includes upper and lower substrates 111 and 112 disposed to face each other at predetermined intervals, and upper and lower substrates 121 and lower substrate 112 formed under the upper substrate 111. Supports the lower electrode 122 formed on the upper side, the insulating film 130 formed on the upper and lower electrodes 121 and 122, and the upper and lower substrates 111 and 112, and isolates pixels to form pixel spaces. And a partition wall 170, a fluid 140 filled in the pixel space, a white particle 150 charged with a positive charge, and a black particle 160 charged with a negative charge.

Here, the type of material constituting each component of the electrophoretic display is well known in the art to which the present invention belongs, and a detailed description thereof will be omitted. In addition, since the present invention is not limited by the physical structure of the electrophoretic display, it can be applied to the electrophoretic display having a structure other than the above-described structure substantially the same.

The driving signal correction apparatus 200 of the electrophoretic display according to the present invention includes a current sensing unit 210, a control unit 220, a voltage driver 230 and a memory unit 240.

The current sensing unit 210 is electrically connected to the upper and lower electrodes 121 and 122 so as to sense a driving current flowing between the upper electrode 121 and the lower electrode 122 of the electrophoretic display pixel 100. do. When the driving signal is applied to the upper and lower electrodes 121 and 122 to drive the electrophoretic display, the current sensing unit 210 senses the driving current flowing through the conductive wires connecting the two electrodes.

The controller 220 receives the current value sensed from the current sensing unit 210, estimates the ambient temperature of the electrophoretic display, and corrects the driving signal according to the estimated temperature to accurately correct the gray scale of the electrophoretic display. To express.

The memory unit 240 corrects the driving signal optimized when the driving signal is applied to the upper and lower electrodes 121 and 122 at various ambient temperature conditions through a preliminary experiment and the corresponding current value (temperature). Contains a look-up table that defines the factor. Here, the driving signal correction factor refers to a factor indicating the degree of correction when correcting the driving signal applied to the electrophoretic display pixel 100 by reflecting the influence of the ambient environment temperature. In addition, the memory unit 240 includes a program for implementing a driving signal correction method of the electrophoretic display according to the present invention. The look-up table may be constructed as shown in Table 1 below.

Current value (A) Estimated Temperature (℃) Drive signal correction factor A1 C1 Factor 1 A2 C2 Factor 2 A3 C3 Factor 3 .
.
. .
.
. .
.
.

3 is a graph showing the change in the current according to the ambient temperature conditions of the electrophoretic display according to the present invention.

Referring to FIG. 3, when a driving signal having a specific waveform is applied to the upper and lower electrodes 121 and 122 of the electrophoretic display pixel 100, a driving current flowing between the upper and lower electrodes 121 and 122 may be affected by the surrounding environment. It turns out that it changes with the temperature (30 degreeC, 40 degreeC, 50 degreeC, 60 degreeC). That is, as the temperature of the surrounding environment increases, the current value in the stabilized state increases. Here, the stabilized state means a state when sufficient time has passed.

The look-up table illustrated in Table 1 above is constructed based on the correlation between the ambient temperature and the current value of the electrophoretic display.

When the current value sensed in Table 1 is A1, the estimated temperature of the surrounding environment is C1, and the driving signal correction factor that can optimize the driving of the electrophoretic display pixel 100 at the temperature C1 becomes factor 1. In the case where the other sensed current value is A2, A3, etc., the driving signal correction factor may be mapped in substantially the same manner as described above.

When the driving current value sensed by the current sensing unit 210 is input, the controller 220 identifies an estimated temperature corresponding to the sensed driving current value by referring to a look-up table stored in the memory unit 240. The drive signal correction factor according to the identified estimated temperature is read. Then, the controller 220 controls the voltage driver 230 in response to the read drive signal correction factor to output a drive signal applied to the upper electrode 121 and the lower electrode 122 of the electrophoretic display pixel 100. Correct.

As an example, when the driving signal correction factor is data indicating a width of increase and decrease with respect to the voltage magnitude of the driving signal, the controller 220 controls the voltage driver 230 according to the driving signal correction factor to display an electrophoretic display pixel ( The driving signal is corrected by increasing or decreasing the voltage level of the driving signal applied to the upper and lower electrodes 121 and 122 of 100. As another example, when the driving signal correction factor is data representing a width of increase and decrease with respect to the holding time of the driving signal, the controller 220 controls the voltage driver 230 according to the driving signal correction factor to display an electrophoretic display pixel ( The driving signal is corrected by increasing or decreasing the application time of the driving signal while maintaining a duty ratio (a ratio of a to b) of the driving signals applied to the upper and lower electrodes 121 and 122 of 100. . On the other hand, the driving signal correction method is not limited to the above, it will be apparent to those skilled in the art that the driving signal can be corrected in various ways.

The voltage driver 230 applies the corrected driving signal to the upper and lower electrodes 121 and 122 of the electrophoretic display pixel 100 under the control of the controller 220.

Hereinafter, the driving signal correction method of the electrophoretic display according to the present invention will be described in more detail with reference to FIGS. 4 to 7.

4 is a flowchart illustrating a method of correcting a driving signal of an electrophoretic display according to the present invention. 5 to 7 are waveform diagrams of driving signals applied to the upper electrode 121 and the lower electrode 122 of the electrophoretic display pixel 100.

2 and 4 to 7, first, in step S10, the controller 220 controls the voltage driver 230 to transmit the initial driving signal 300 to the upper and lower electrodes of the electrophoretic display pixel 100. (121, 122). Since the + Vss voltage and the -Vss voltage are repeatedly applied to the upper and lower electrodes 121 and 122 at regular intervals, the gray scale is displayed on the electrophoretic display pixel 100. Here, it is assumed that the initial driving signal 300 is a driving signal capable of expressing an accurate grayscale at a reference temperature (eg, 25 ° C).

In operation S20, the current sensing unit 210 senses a driving current flowing between the upper and lower electrodes 121 and 122. In addition, the sensed current value is input to the controller 220.

In operation S30, the controller 220 identifies the estimated temperature corresponding to the driving current value applied from the current sensing unit 210 with reference to the look-up table stored in the memory unit 240, and identifies the identified estimated temperature. Leads to a drive signal correction factor.

In operation S40, the controller 220 controls the voltage driver 230 according to a driving signal correction factor to output driving signals applied to the upper electrode 121 and the lower electrode 122 of the electrophoretic display pixel 100. Correct. As described above, when the driving signal is corrected, the influence of the ambient environment temperature is canceled to enable accurate grayscale expression.

6 shows a state in which the voltage magnitude of the driving signal is increased according to the driving signal correction factor. This can usually occur when the ambient temperature of the electrophoretic display is lower than the reference temperature or the viscosity of the fluid 140 in the electrophoretic display is increased so that the drive current value is lower than the reference, making it difficult to accurately represent grayscale. The corrected drive signal 301 has a larger voltage magnitude (h ') than the voltage magnitude (h) of the initial drive signal 300, so that the moving speed of the white and black particles (150, 160) of the electrophoretic display is improved. You will be able to express accurate grayscales.

7 illustrates a state in which an application time of a driving signal is increased according to a driving signal correction factor. This may also occur when the ambient temperature of the electrophoretic display is lower than the reference temperature or if the fluid 140 viscosity in the electrophoretic display is increased so that the drive current value is lower than the reference, making it difficult to accurately represent grayscale. The corrected drive signal 302 has the same duty ratio but the drive signal period T 'is longer than the drive signal period T of the initial drive signal 300. Therefore, the white and black particles 150 and 160 of the electrophoretic display are sufficiently secured to move, so that more accurate gray scales can be expressed.

In step S50, the controller 220 determines whether the driving of the electrophoretic display is continued. If the driving of the electrophoretic display does not continue, the process for correcting the drive signal of the electrophoretic display is terminated. On the other hand, if the driving of the electrophoretic display is continued, the control unit 220 proceeds to step S20.

In step S20 to step S50, the control unit 220 periodically receives a current value from the current sensing unit 210 while driving of the electrophoretic display is continued to correct the driving signal by the feedback control. It will be apparent to those skilled in the art that the present invention will be repeated.

Meanwhile, the above-described embodiment has been described based on a method of correcting a driving signal based on unit pixels of an electrophoretic display. However, the present invention can be applied to the driving of a matrix in which a plurality of electrophoretic display pixels 100 are two-dimensionally arranged. In this case, it is desirable to correct the driving signal for each pixel constituting the matrix. To this end, the driving signal correction apparatus 200 described above is provided for each pixel, and the control unit 220 scans the current value of each cell through the current sensing unit 210 connected to each pixel, and then drives the driving signal for each cell. The correction factor may be read from the look-up table stored in the memory unit 240 to control the voltage driver 230 connected to each cell according to the scan order of each cell to correct the driving signal for each cell. Then, even if there is a performance deviation or a temperature deviation between the unit pixels, it is possible to accurately represent the grayscale as a whole.

The driving signal correction method of the electrophoretic display according to the present invention described above may be implemented in the form of program instructions that can be executed by various computer means and recorded in a computer-readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those skilled in the computer program arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Hardware devices specially configured to store and execute program instructions such as magneto-optical media and ROM, RAM, flash memory and the like. The medium may be a transmission medium such as an optical or metal line, a wave guide, or the like, including a carrier wave for transmitting a signal designating a program command, a data structure, or the like. Examples of program instructions include machine code, such as produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter. Such hardware devices may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

The following drawings, which are attached to this specification, illustrate preferred embodiments of the present invention, and together with the detailed description of the present invention serve to further understand the technical idea of the present invention, the present invention includes the matters described in such drawings. It should not be construed as limited to.

1 is a cross-sectional view schematically showing one pixel in a typical electrophoretic display.

2 is a block diagram showing the configuration of a drive signal correction apparatus of an electrophoretic display according to a preferred embodiment of the present invention.

3 is a graph showing the change in the current according to the ambient temperature conditions of the electrophoretic display according to the present invention.

4 is a flowchart illustrating a method of correcting a driving signal of an electrophoretic display according to the present invention.

5 is a waveform diagram illustrating an initial driving signal applied to an electrophoretic display pixel according to the present invention.

FIG. 6 is a waveform diagram illustrating a drive signal corrected for the initial drive signal shown in FIG. 5 according to an embodiment of the present invention.

FIG. 7 is a waveform diagram illustrating a drive signal corrected for the initial drive signal shown in FIG. 5 according to another embodiment of the present invention.

<Main reference number in drawing>

200: drive signal correction device of the electrophoretic display

210: current sensing unit 220: control unit

230: voltage driver 240: memory

Claims (12)

In the drive signal correction device of the electrophoretic display, A voltage driver configured to apply driving signals to upper and lower electrodes of the electrophoretic display; A current sensing unit sensing a driving current flowing between the upper and lower electrodes; A memory unit for storing a look-up table that defines a driving signal correction factor according to the magnitude of the driving current; And And a controller configured to correct a driving signal applied to the upper and lower electrodes by reading a driving signal correction factor corresponding to the sensed current from the look-up table and then controlling the voltage driver according to the driving signal correction factor. But The drive signal correction factor is data representing a width of increase and decrease with respect to the holding time of the drive signal. And the control unit corrects the driving signal by controlling a voltage driving unit according to the driving signal correction factor to adjust an application time of driving signals applied to upper and lower electrodes. The method of claim 1, The drive signal correction factor is a drive signal correction device of the electrophoretic display, characterized in that consisting of data indicating the degree of correction for the drive signal. The method of claim 1, The drive signal correction factor is data representing a width of increase and decrease with respect to the voltage magnitude of the drive signal. And the control unit corrects the driving signal by controlling a voltage driving unit according to the driving signal correction factor to adjust voltage levels of the driving signals applied to the upper and lower electrodes. delete The method of claim 1, The control unit is a drive signal correction device for an electrophoretic display, characterized in that to maintain a constant duty ratio of the drive signal. The method of claim 1, And the controller periodically receives a current value from the current sensing unit and corrects the driving signal by a feedback control. In the drive signal correction method of the electrophoretic display, (a) constructing a look-up table that defines a drive signal correction factor according to the drive current magnitude of the electrophoretic display; (b) applying a drive signal to upper and lower electrodes of the electrophoretic display; (c) sensing a driving current flowing between the upper and lower electrodes; (d) reading a drive signal correction factor corresponding to the sensed drive current from the look-up table; And (e) correcting driving signals applied to the upper and lower electrodes according to the driving signal correction factor, The drive signal correction factor is data representing a width of increase and decrease with respect to the holding time of the drive signal. Wherein (e), the drive signal correction method of the electrophoretic display characterized in that for correcting the drive signal by adjusting the holding time of the drive signal applied to the upper and lower electrodes according to the drive signal correction factor. The method of claim 7, wherein The drive signal correction factor is data representing a width of increase and decrease with respect to the voltage magnitude of the drive signal. And (e) correcting the driving signal by adjusting the voltage magnitudes of the driving signals applied to the upper and lower electrodes according to the driving signal correction factor. delete The method of claim 7, wherein In the step (e), the duty ratio of the driving signals applied to the upper and lower electrodes is constantly maintained. The method of claim 7, wherein The steps (c) to (e) are repeated at regular intervals by a feedback control method. 12. A computer-readable recording medium recording and programming a method for correcting a driving signal of an electrophoretic display according to any one of claims 7 to 11.

Images