JP2007017547A - Driving method of electrophoresis display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving method of an electrophoresis display capable of compensating a residual DC component and obtaining a satisfactory display state. <P>SOLUTION: An electric field is formed in a dispersion liquid 10 comprising an insulating liquid and a plurality of charged migration particles 8 and 9 disposed in a gap between a pair of substrates 1 and 2 by applying voltage between first and second electrodes 7 and 5 and the charged migration particles 8 and 9 are transferred between the first and the second electrodes 7 and 5 to perform display. The voltage applied between the electrodes at the reset operation time when voltage is applied between the electrodes to rest display is adjusted so that the voltage applied to the dispersion liquid 10 at the time when writing operation for applying writing voltage between the electrodes to perform display is completed is made nearly equal to capacitance partial pressure of a serial capacitance of insulating films 11 and 12 insulating the first and the second electrodes 7 and 5 and the dispersion liquid 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for driving an electrophoretic display device, and more particularly to compensation for residual DC.

  In recent years, with the development of information equipment, the need for low power consumption and thin display devices has increased, and research and development of display devices that meet these needs are being actively conducted.

  Such a display device is often used outdoors especially for applications such as wearable PCs and electronic notebooks, and is desired to have low power consumption and space saving. For example, a thin display such as a liquid crystal display The display function and coordinate input processing are integrated, and a product that can be directly input by pressing the content displayed on the display with a pen or a finger has been commercialized.

  However, since many liquid crystals do not have so-called memory properties, it is necessary to continue applying voltage to the liquid crystals during the display period. On the other hand, a liquid crystal having a memory property has not been put into practical use because it is difficult to ensure reliability when it is assumed to be used in various environments such as a wearable PC.

  Therefore, as one of thin and light display systems having memory characteristics, Harold D. et al. An electrophoretic display device has been proposed by Lee et al. (Patent Document 1).

  This type of electrophoretic display device includes a pair of substrates arranged with a predetermined gap therebetween, an insulating liquid filled between these substrates, and a large number of colored charged particles dispersed in the insulating liquid. And an electrophoretic display element provided with display electrodes arranged in each pixel along each substrate.

  Here, in the electrophoretic display element, since the colored charged particles are charged positively or negatively, the colored charged particles can be seen by adsorbing the colored charged particles to the upper electrode, for example, by the applied voltage, or Various images can be displayed by adsorbing colored charged particles to the lower electrode so that the color of the insulating liquid can be seen. An electrophoretic display device including such an electrophoretic display element is referred to as a vertically moving electrophoretic display device.

  And, for example, an active matrix type electrophoretic display device driving method utilizing such memory characteristics includes a reset period and a write operation period. When an image is displayed, coloring is first performed in the reset period. In order to align the migrating particles at a predetermined position, a reset voltage is written to each pixel electrode.

  Next, in the write operation period, a constant voltage is applied to each pixel electrode only for a period corresponding to the gradation value indicated by the image data, or for a certain period, only a voltage corresponding to the gradation value indicated by the image data. Thereafter, the common electrode voltage is written to each pixel electrode. As a result, the charge accumulated in the pixel capacitor is discharged and the display image is held (see Patent Document 2 or 3).

US Patent No. USP36127758 JP 2002-116733 A JP 2002-116734 A

  By the way, in such a conventional method of driving an electrophoretic display device, since the colored charged particles are charged to positive polarity or negative polarity, it is assumed that the writing operation is unipolar driving of positive or negative voltage. However, when unipolar voltage driving is performed in this way, a DC component remains in the electrophoretic display element.

  If writing according to only the gradation value indicated by the image data is performed with the DC component remaining in this manner, a desired gradation value display may not be obtained. This is because the residual DC component causes a difference between the applied voltage at the time of writing and the effective voltage applied to the electrophoretic display element. The phenomenon in which a desired gradation value display cannot be obtained due to the remaining DC component is called burn-in.

  Hereinafter, image sticking and residual DC will be described in detail with reference to FIG.

  FIG. 10 shows an example of the configuration of a conventional electrophoretic display element. This electrophoretic display element includes positively charged black charged electrophoretic particles 21, negatively charged white charged electrophoretic particles 22, and An electrode comprising a dispersion liquid 23 including a dispersion medium that is an insulating liquid and a plurality of charged electrophoretic particles 21 and 22, and a first electrode 24 and a second electrode 25 for applying an electric voltage to form an electric field in the dispersion liquid. A thin insulating film 26 separating the liquid dispersion 23 and the first electrode 24, a thin insulating film 27 separating the dispersion 23 and the second electrode 25, and a partition wall 28 separating the adjacent pixels are provided.

  In this type of electrophoretic display element, the relaxation time constant of the charge at each part varies depending on the physical properties of each member. Here, if the time constant of the dispersion portion is τ1, the time constant of the insulating film portion is τ2, and there is a relationship of τ1 << τ2 between the two time constants τ1 and τ2, for example, the first electrode 24 and the first electrode When a unipolar voltage is continuously applied between the two electrodes 25, charges accumulate at both ends of the thin insulating film portion where τ2 is large and charges are difficult to accumulate.

  Here, since the insulating film portion has a long charge relaxation time, the charge remains for a long time even when the voltage between the electrodes is set to 0V. As a result, although 0 V is applied between the electrodes, an internal voltage due to residual charges is generated at the upper and lower ends of the dispersion portion. The voltage difference generated in this way is the residual DC. Due to this residual DC, a voltage different from the applied voltage is applied to the upper and lower ends of the dispersion portion, and burn-in occurs. As a result, when a write operation referring only to image information to be displayed is performed, a desired voltage cannot be applied to the display element, and a desired display state cannot be obtained.

  FIG. 11 shows the voltage waveform applied to the electrodes and the voltage waveform applied to the dispersion liquid portion. In the reset period (t1 to t2), charges accumulate in the insulating films 26 and 27 with time, and the dispersion liquid The voltage applied to 23 decreases. Further, in the address period (t2 to t3), the charge accumulated at the time of resetting is added, so that a voltage higher than the voltage applied to the electrode is applied to the dispersion liquid 23. Accordingly, since the charge accumulated in the writing period (t2 to t3) becomes larger than that in the reset period, overshoot occurs when 0 V is applied thereafter.

  Here, in a display device with a fast response speed, the pulse application time can be shortened, so the amount of overshoot is also small, which is not a problem. However, in a device with a slow response speed such as an electrophoretic display device, pulse application is performed. Since the time becomes longer, the above-mentioned problem appears remarkably.

  On the other hand, an active matrix electrophoretic display device has a configuration in which a desired voltage is written to a pixel electrode via a switching element such as a thin film transistor (TFT) that is a thin film transistor, and then the voltage is held. ing. The writing time is several tens of microseconds, which is sufficiently shorter than the migration speed of the charged particles, and charged charged particles migrate while maintaining a voltage.

  At this time, since the pixel electrode is in a floating state, the pixel potential changes according to the migration distance of the charged particles. As a result, when a write operation referring only to image information to be displayed is performed, a desired voltage cannot be applied to the display element, and a desired display state cannot be obtained.

  Accordingly, the present invention has been made in view of such a current situation, and an object thereof is to provide a driving method of an electrophoretic display device capable of compensating for residual DC and obtaining a good display state. It is.

  The present invention provides a pair of substrates arranged with a gap, a dispersion composed of an insulating liquid and a plurality of charged electrophoretic particles arranged in the gap between the pair of substrates, and an electric field in the dispersion And an insulating film that insulates the dispersion from the first electrode and the second electrode, and a voltage is applied between the first electrode and the second electrode to disperse the dispersion. In an electrophoretic display device driving method for performing display by forming an electric field therein and moving the charged electrophoretic particles between the first electrode and the second electrode, between the first electrode and the second electrode. A reset operation for resetting the display by applying a voltage to the first electrode and a write operation for performing a display by applying a write voltage between the first electrode and the second electrode, and the first electrode during the reset operation. And the voltage applied between the second electrode and the second electrode The voltage applied to the dispersion at the end of the pouring operation is adjusted so as to be approximately equal to the partial pressure of the series capacitance of the insulating film and the dispersion. .

  As in the present invention, the voltage applied between the first electrode and the second electrode at the time of the reset operation is the same as the voltage applied to the dispersion at the end of the write operation. By adjusting the pressure so as to be approximately equal to the pressure, it is possible to compensate for the residual DC at the end of writing, thereby obtaining good display characteristics.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an electrophoretic display element provided in an electrophoretic display device driven by the electrophoretic display device driving method according to the first embodiment of the present invention. Reference numeral 1 denotes a first substrate, and reference numeral 2 denotes a second substrate disposed with a gap from the first substrate 1. Here, the 1st board | substrate 1 is comprised with light transmissive boards, such as transparent glass and a transparent film, for example. Note that the second substrate 2 is not necessarily transparent, and may be formed of a film substrate, a metal substrate, or the like.

  A transparent first electrode 7 is formed on the first substrate 1, and a second electrode 5 is formed on the second substrate 2. Here, as the first electrode 7, not only an ITO film (indium tin oxide film) but also a metal film such as an Al film may be used. In addition to the film, a metal film such as an Al film may be used. A drive voltage generator shown in FIG. 2, which will be described later, is connected between the first and second electrodes 5 and 7.

  In addition, a partition wall 6 that is a partition member is provided between the first substrate 1 and the second substrate 2 that are a pair of substrates, and the partition wall 6 forms a gap between the first substrate 1 and the second substrate 2. It is held constant. Here, as a material of the partition wall 6, a generally used resist material, a thermoplastic material, an ultraviolet curable material, or the like can be used. The thickness of the partition wall 6, that is, the distance between the electrodes is usually about 5 μm to 1 mm.

  Further, in a space surrounded by the partition wall 6 and the first and second substrates 1 and 2, positively charged black charged electrophoretic particles 8, negatively charged white charged electrophoretic particles 9, and insulating properties are provided. A dispersion liquid 10 including a liquid dispersion medium and a plurality of charged electrophoretic particles 8 and 9 is filled.

  Here, examples of the dispersion medium include water, methanol, ethanol, acetone, hexane, toluene, aromatic hydrocarbons such as benzenes having a long-chain alkyl group, and other various oils alone or a mixture thereof. A compound containing a surfactant and the like can be used.

  Further, the charged electrophoretic particles 8 and 9 are organic or inorganic particles having a property of moving by electrophoresis due to a potential difference in a dispersion medium. Examples of such charged electrophoretic particles 8 and 9 include aniline black and carbon. One type or two or more types of black pigments such as black, white pigments such as titanium dioxide and antimony trioxide, azo pigments, and other colored pigments can be used. For these pigments, if necessary, a charge control agent composed of particles of electrolyte, surfactant, resin, rubber, oil, etc., titanium coupling agent, aluminum coupling agent, silane coupling agent, etc. A dispersant, a lubricant, a stabilizer and the like can be added.

  Thin insulating films 11 and 12 are provided on the surfaces of the first electrode 7 and the second electrode 5, respectively. The insulating films 11 and 12 allow the dispersion liquid 10 and the first and second electrodes 5 and 7 to be separated from each other. Insulation is made between them. As the insulating films 11 and 12, polyethylene, polycarbonate, polyimide, acrylate copolymer, silicon oxide, or the like can be used.

  Next, the driving operation of the electrophoretic display element configured as described above will be described. In the following description, the case where the charged electrophoretic particles are positively charged will be described as an example.

  FIG. 2 shows the equivalent circuit of FIG. 1. In FIG. 2, Rep and Cep indicate the resistance and capacitance of the dispersion layer, and R1, R2, C1, and C2 indicate the resistance and capacitance of the insulating film portion, respectively. Represents. In general, the dispersion 10 contains charged particles and counter ions, so that the Rep is small and the insulating films 11 and 12 are thin, so that the relationship of Rep, R1, R2, and Cep, C1, C2 Rep <R1, Rep <R2, Cep <C1, Cep <C2.

  FIG. 3 shows a driving waveform of the electrophoretic display element. When the reset voltage Vr1 is applied as a reset operation between the electrodes at time t1, the voltage ΔVep0 applied to the dispersion 10 is Cep and C1, The pressure is divided according to the capacity of C2, and is expressed by the following formula 1.

  Thereafter, during the period up to t2, the voltage Vep applied to the dispersion 10 changes according to the function F so as to exponentially approach the resistance partial pressure value Vr1 × Rep / (R1 + Rep + R2). As a result, the dispersion 10 The voltage ΔVep1 applied to is as shown in Equation 2 below.

Next, in the writing period, when the applied voltage changes from Vr1 to the writing voltage Vw1 having the opposite polarity as the writing operation, the voltage applied to the dispersion liquid 10 is divided by the capacitance divided as shown in the following formula 3. fluctuate.

  Thereafter, during the period up to t3, it changes according to the function F so as to approach the resistance partial pressure, and as a result, the voltage ΔVep3 applied to the dispersion 10 becomes as shown in the following equation 4.

Next, when 0 V is applied between the electrodes after the writing is completed, the voltage applied to the dispersion liquid 10 fluctuates by the capacity partial pressure shown by the following formula 5.

From the above formulas 1 to 5, the voltage applied to the dispersion 10 at time t4 is expressed by the following formula.

  Here, in Equation 6, in order for Vep (t4) to be 0V and the overshoot amount to be 0,

It is sufficient that the above condition is satisfied, and this can be achieved by adjusting the magnitude of ΔVep0 in advance.

  Here, since the right side of Expression 7 corresponds to the voltage Vep (t3) applied to the dispersion 10 at the end of writing, if this voltage Vep (t3) is rewritten using Expression 5,

となる。

It becomes.

  That is, at the end of writing, the voltage applied to the dispersion 10 only needs to be equal to the volume partial pressure of the series capacitance of the insulating films 11 and 12 and the dispersion 10, and in order to prevent the seizure from being seen, It may be 1% or less of the maximum applied voltage required for optical modulation.

  Hereinafter, a specific example of the present embodiment will be described.

  First, an electrophoretic display element having a cell gap of 40 μm, a square of 100 μm × 100 μm and a size of 1024 × 768 pixels was manufactured. Here, isoparaffin (trade name: Isopar, manufactured by Exxon) was used as a dispersion medium, and a polystyrene-polymethyl methacrylate copolymer resin containing carbon black having a particle size of about 1 to 2 μm was used as the charged electrophoretic particles. The isoparaffin contained succinimide (trade name: OLOA 1200, manufactured by Chevron) as a charge control agent. Further, polyimide was used as the insulating film, and ITO was used for the first and second electrodes.

  Next, the capacitance and resistance of each film of the electrophoretic display element were measured using an impedance analyzer. The results were as follows.

C1 = C2 = 12.2 μF
R1 = R2 = 2.5 × 10 ¹⁰ Ω
Cep = 4.4nF
Rep = 1.5 × 10 ⁶ Ω

  And when voltage 5V was applied between the electrodes of such an electrophoretic display element for 2 seconds and the residual DC voltage was measured with a residual DC measuring instrument (6254 type manufactured by Toyo Technica Co., Ltd.), it was -0.98V. Similarly, when the amount of residual DC was measured for applied voltages of 10 V, 20 V, and 30 V, the result was as shown in FIG. From this result, it can be seen that the applied voltage and the residual DC are in a proportional relationship, and linear approximation is possible.

  Here, if the slope of this straight line is D, Equations 2 and 4 are respectively

と近似できる。

Can be approximated.

  Then, by substituting these formulas 9, 10 and 1, 3, 3 and 5 into the formula 7, the following formula 11 is obtained, and this formula 11 is necessary to cancel the residual DC. The reset voltage can be calculated.

  Here, since the optical response time of the electrophoretic display element was 2 seconds, the reset time and the writing time were set to 2 seconds, respectively, and since D = −0.195 from FIG. 4, the writing voltage Vw1 The reset voltage Vr1 in the case of 20V is found to be −24.8V.

  Actually, a waveform of Vr1 = −24.8V for 2 seconds and then Vw1 = 20V for 2 seconds is applied between the electrodes of the electrophoretic display device, and the residual DC amount immediately after writing is measured by a residual DC measuring instrument (Toyo Technica) It was -13 mV when measured by 6254 type).

  On the other hand, when a waveform in which the integrated value of the applied voltage is 0 as in the conventional case, for example, a waveform of Vr1 = −20V for 2 seconds and Vw1 = 20V for 2 seconds is applied, the residual DC is − It was 770 mV.

  From the above results, it was confirmed that by adopting the driving method of the present invention, the residual DC can be reduced to about 1/59 of the conventional driving method, and a good display without image sticking can be obtained. .

  In this way, the reset voltage Vr1 applied between the electrodes during the reset operation is set so that the voltage applied to the dispersion 10 at the end of the write operation is substantially equal to the capacity partial pressure of the series capacitance of the insulating film and the dispersion. By adjusting to, residual DC at the end of writing can be compensated for, and thereby good display characteristics can be obtained.

  This embodiment is a case where the insulating films 11 and 12 are formed on both sides of the dispersion liquid 10, but an equivalent circuit is the same as that of this embodiment when there is an insulating film only on one side of the dispersion liquid. It is effective even in different cases.

  Next, a second embodiment of the present invention will be described.

  FIG. 5 is a diagram showing driving waveforms in the driving method of the electrophoretic display device according to the present embodiment, and FIG. 5 shows a case where the write voltage Vw1 is small. Here, when the write voltage Vw1 is small in this way, the reset voltage Vr1 requires a voltage higher than a certain level in order to align the particle position at a certain position, so a small reset voltage cannot be applied.

  Therefore, when the writing voltage Vw1 is small as in the present embodiment, the writing period (t2 to t3) is lengthened, and the voltage applied to the dispersion at the end of writing is the series capacitance of the insulating film and the dispersion. It is adjusted so as to be equal to the capacity partial pressure. Then, by adjusting the voltage applied between the electrodes for each write voltage Vw1 during the reset operation in this way, the same effects as those of the first embodiment described above can be obtained.

  Next, a third embodiment of the present invention will be described.

  FIG. 6 is a diagram showing a driving waveform in the driving method of the electrophoretic display device according to this embodiment, and FIG. 6 shows a case where the writing voltage is small. Here, when the write voltage is small as described above, the reset voltage is not uniform because the particle position is aligned at a certain position, and a voltage higher than a certain level is required.

  Therefore, when the write voltage Vw1 is small in this way, in this embodiment, a compensation pulse that is a compensation signal is inserted before a reset pulse that is a reset signal, and the voltage applied to the dispersion at the end of the write is The adjustment is made to be equal to the volume partial pressure of the series capacity of the insulating film and the dispersion.

  Here, similarly to the first embodiment described above, the voltage Vep applied to the dispersion is described as shown in the following formulas 12 to 18, respectively.

  The voltage applied to the dispersion at time t5 is expressed by the following equation 19.

  And in order for Vep (t5) to be 0V and overshoot amount to be 0 in Equation 19,

の条件を満たしていれば良い。

As long as the above conditions are satisfied.

  Therefore, by substituting Equations 12 to 18 into Equation 20 and modifying it, the following Equation 21 is obtained. From this Equation 21, the voltage Vc of the compensation pulse necessary for canceling the residual DC can be calculated.

  Here, when D = −0.195, an electrophoretic display element similar to that of the first embodiment is driven under the condition that the reset voltage Vr1 = −20V, the write voltage Vw1 = + 4V, and each pulse width is 2 seconds. The voltage Vc of the compensation pulse is obtained as + 18.7V.

  When Vc = + 18.7V, Vr1 = −20V, and Vw1 = + 4V were applied for 2 seconds between the electrodes of the electrophoretic display element, and the residual DC amount immediately after writing was measured with a residual DC measuring instrument, −1.2 mV Met.

  On the other hand, when a waveform in which the integrated value of the applied voltage becomes 0 as in the conventional case, for example, a waveform of Vc = + 16V, Vr1 = −20V, Vw1 = + 4V for 2 seconds, is applied, the residual DC Was +341 mV, so that the reset DC and the compensation pulse applied before the reset pulse are reset at the time of the reset operation. It turned out that it can reduce to 1/280.

  From this result, even in the case of a driving waveform composed of a plurality of pulses, the driving method of the present invention is effective and a good display without burn-in can be obtained. Furthermore, in the present embodiment, the reset voltage can be fixed regardless of the write voltage, that is, since the reset voltage is constant, a more stable display can be obtained than in the first embodiment.

  Next, a fourth embodiment of the present invention will be described.

  FIG. 7 is a block diagram showing a system configuration of an electrophoretic display element driven by the driving method of the electrophoretic display device according to the present embodiment. In FIG. 7, 41 is a panel controller, 43 is a source driver, 42 Is a gate driver, and 44 is an electrophoretic display panel using an electrophoretic display element.

  Here, the panel controller 41 generates a control signal such as a field synchronization signal, a horizontal synchronization signal, a data capture clock, and display data based on the input image data, and transfers it to the source driver 43 and the gate driver 42. The source driver 43 and the gate driver 42 output drive voltages to the electrophoretic display panel 44 in accordance with control signals and display data received from the panel controller 41. The electrophoretic display panel 44 performs display according to this drive voltage.

  The electrophoretic display panel 44 includes a plurality of data line groups (not shown) wired on the first substrate at regular intervals and three-dimensionally intersecting the plurality of data line groups at regular intervals on the first substrate. A plurality of pixels arranged at regular intervals are provided corresponding to the intersections of the scanning line group and auxiliary capacitance line group (not shown) and the plurality of data lines and scanning lines.

  FIG. 8 is a diagram showing an equivalent circuit in one pixel of the electrophoretic display panel 44. The second electrode 5 of the pixel 45 is a thin film transistor (hereinafter referred to as TFT) which is a switching element for active matrix drive display. The first electrode 7 is connected to a common electrode 49 having a voltage Vcom.

  Note that the first electrodes 7 of all the pixels are connected to the common electrode 49. The gate line 47 as a scanning line is connected to the gate electrode of the TFT 46, and the source line 48 as the data line is connected to the source electrode of the TFT 46. Further, an auxiliary capacitor 50 is connected to the drain electrode.

  Hereinafter, a specific driving method will be described.

  FIG. 9 shows various signal waveforms for one pixel of the electrophoretic display panel 44. 9A shows a gate signal (scanning signal pulse) input from the gate driver 42, FIG. 9B shows an information signal pulse input from the source driver 43 to the second electrode 2, and FIG. (C) of FIG. 9 shows the voltage waveform between the pixel electrodes and the voltage waveform applied to the upper and lower ends of the dispersion portion, and FIG. 9 (d) shows the optical response.

  In the present embodiment, the residual DC correction drive uses reset, and when resetting, not only aligns the particle position of each pixel to the initial state (black state) but also cancels the residual DC at the end of writing. It shall be adjusted so that In the driving method shown in FIG. 9, black is displayed as the previous state of the reset field 1, and the same gradation is written twice after the period T1.

  First, in the reset field 1, the reset pulse Vr1 is applied from the source driver 43 in synchronization with the gate pulse, and the voltage Vr1 is written to the pixel. Thereafter, the voltage is held during the reset field 1 period. At this time, the voltage applied to the dispersion changes as shown in FIG. 9C because it approaches the resistance partial pressure as described above.

  Next, when moving to the writing field 1, the voltage Vw1 is written to the pixel, and then the voltage is held, and the display state changes from black to white by the movement of the charged electrophoretic particles. At this time, the writing time is sufficiently shorter than the migration speed of the charged electrophoretic particles, and the charged electrophoretic particles charged while the voltage is maintained migrate.

  At this time, since the pixel electrode is in a floating state, the pixel potential varies due to the movement of the charged electrophoretic particles. Specifically, the voltage between the electrodes decreases, and the voltage applied to the dispersion also changes accordingly as shown in (c) of FIG.

  However, even when the charged electrophoretic particles move in such a short writing time, the voltage applied to the dispersion at the end of the moving writing is previously set to be equal to the capacity partial pressure of the series capacity of the insulating film and the dispersion. Since it is adjusted by the reset voltage Vr1, there is almost no overshoot due to subsequent 0V writing, and a desired gradation level is maintained.

  Next, after a period T1, resetting for rewriting the same gradation is performed. However, since this is reset accompanied by movement of the charged electrophoretic particles, pixel potential fluctuation due to movement of the charged electrophoretic particles also occurs in the reset field 2. Apply the considered voltage Vr2. That is, at the end of the reset field 2, the voltage applied to the dispersion is made substantially the same as at the end of the reset field 1.

  Thereafter, from the writing field 2, the same operation as that of the writing field 1 is performed, and an overshoot due to 0V writing immediately after the writing field 2 is almost eliminated, and a desired gradation level is maintained. With the driving method described above, no display burn-in phenomenon was observed.

  In the above description, the vertical movement type electrophoretic display device has been described as an example. However, the present invention can also be applied to a horizontal movement type electrophoretic display device. In addition, the integrated value of the applied voltage is not made zero, but if the residual DC can be made substantially zero at the end of writing, the charged electrophoretic particles and the dispersion medium are included in each of a number of microcapsules. The present invention can also be applied to an electrophoretic display device having the structure described above.

1 is a diagram showing a schematic configuration of an electrophoretic display element provided in an electrophoretic display device driven by a method for driving an electrophoretic display device according to a first embodiment of the invention. FIG. 4 is a diagram illustrating an equivalent circuit of a pixel in the electrophoretic display element. The figure which shows the drive waveform of the said electrophoretic display element. The figure showing the relationship between the voltage applied to the said electrophoretic display element, and a residual DC measured value. FIG. 10 is a diagram illustrating a driving waveform in the driving method of the electrophoretic display device according to the second embodiment of the invention. FIG. 10 is a diagram illustrating a driving waveform in the driving method of the electrophoretic display device according to the third embodiment of the invention. The block diagram which shows the system configuration | structure of the electrophoretic display element driven with the drive method of the electrophoretic display apparatus which concerns on the 4th Embodiment of this invention. FIG. 3 is a diagram showing an equivalent circuit in one pixel of an electrophoretic display panel provided in the electrophoretic display device. The figure which shows the drive waveform of one pixel of the said electrophoretic display panel. Sectional drawing of one pixel of the conventional electrophoretic display element. The figure which shows the drive waveform of the said conventional electrophoretic display element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 2nd board | substrate 5 2nd electrode 7 1st electrode 6 Partition 8 and 9 Charged electrophoretic particle 10 Dispersion liquid 11 and 12 Insulating film 44 Electrophoretic display panel Vc Compensation pulse voltage Vw1 Write voltage Vr1 Reset voltage

Claims (9)

A pair of substrates arranged with a gap therebetween, a dispersion composed of an insulating liquid and a plurality of charged electrophoretic particles arranged in the gap between the pair of substrates, and a first electrode for forming an electric field in the dispersion And an insulating film that insulates the dispersion from the first electrode and the second electrode, and a voltage is applied between the first electrode and the second electrode to generate an electric field in the dispersion. In an electrophoretic display device driving method for forming and displaying by moving the charged electrophoretic particles between the first electrode and the second electrode,
A reset operation for resetting the display by applying a voltage between the first electrode and the second electrode;
A write operation in which display is performed by applying a write voltage between the first electrode and the second electrode;
With
The voltage applied between the first electrode and the second electrode at the time of the reset operation is the same as the voltage applied to the dispersion at the end of the write operation, which is equal to the capacitance of the series capacitance of the insulating film and the dispersion. A method for driving an electrophoretic display device, wherein the electrophoretic display device is adjusted to be substantially equal to a pressure.   The voltage applied between the first electrode and the second electrode at the time of the reset operation is the same as the voltage applied to the dispersion at the end of the write operation, which is equal to the capacitance of the series capacitance of the insulating film and the dispersion. 2. The method for driving an electrophoretic display device according to claim 1, wherein a difference from the pressure is adjusted to be 1% or less of the maximum applied voltage.   3. The driving of an electrophoretic display device according to claim 1, wherein a voltage applied between the first electrode and the second electrode during the reset operation is adjusted for each of the write voltages. Method. The write voltage is Vw1, the residual DC amount generated per 1V applied between the first electrode and the second electrode is D, and the reset is applied between the first electrode and the second electrode during the reset operation. When the voltage of the signal is Vr1, the voltage Vr1 of the reset signal is

The driving method of the electrophoretic display device according to claim 1, wherein the driving method is determined by:   3. The method for driving an electrophoretic display device according to claim 1, wherein the display is reset using a reset signal and a compensation signal applied before the reset signal during the reset operation. If the write voltage is Vw1, the residual DC amount generated per 1V applied between the first electrode and the second electrode is D, the voltage of the compensation signal is Vc, and the voltage of the reset signal is Vr1. The voltage Vc of the compensation signal is

The driving method for an electrophoretic display device according to claim 5, wherein:   7. The method for driving an electrophoretic display device according to claim 6, wherein the voltage Vr1 of the reset signal is constant regardless of the write voltage Vw1.   8. The method of driving an electrophoretic display device according to claim 4, wherein the reset signal voltage Vr1 and the write voltage Vw1 have opposite polarities. 3. The electrophoretic display device according to claim 1, wherein a voltage applied between the first electrode and the second electrode during the reset operation is adjusted according to a write voltage application time. Driving method.

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