JP2015176133A - Driving unit and driving method for electrophoretic display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving unit and a driving method for an electrophoretic display device that allow reduction of a ghost image even if a display image is rewritten at high-speed.SOLUTION: A driving unit of an electrophoretic display device including pixels performing display with two electrodes holding an electrophoretic display material and an electrophoretic display material therebetween applies a flashing pulse including a first potential and a second potential in this order between the two electrodes, and thereafter, applies an addressing pulse between the two electrodes.

Description

  The present invention relates to a driving device and a driving method for an electrophoretic display device.

  As an example of an electro-optical device, an image is obtained by moving an electrophoretic particle by applying a voltage between a pixel electrode and a counter electrode provided so as to sandwich an electrophoretic element having a dispersion medium containing the electrophoretic particle. There is an electrophoretic display device (EPD: Electronic Paper Display) (see, for example, Patent Document 1). The electrophoretic element includes, for example, black particles and white particles as the electrophoretic particles, and these two kinds of particles are selectively attracted to the counter electrode side for each pixel, so that two gradations of black or white are obtained. Is displayed. In such an electrophoretic display device, an image is displayed by supplying a data potential corresponding to a gradation to be displayed to a pixel electrode provided in each of a plurality of pixels. For example, the pixel electrode of a pixel that should display black is supplied with a positive potential VSH (for example, +15 V) that is higher than the potential GND (for example, 0 V) of the counter electrode as the data potential, and at the same time, the pixel that should display white An image is displayed on the pixel electrode by supplying a negative potential -VSH (for example, -15 V) lower than the potential of the counter electrode.

  On the other hand, as such an electrophoretic display device, each of a plurality of pixels arranged in a matrix corresponding to the intersection of a plurality of scanning lines and a plurality of data lines intersecting each other serves as a pixel switching element. Active matrix drive type electrophoretic display including a pixel circuit (a so-called 1T1C type pixel circuit) including a TFT (Thin Film Transistor) and one capacitor (that is, a storage capacitor) that functions as a memory circuit. There is a device (see, for example, Patent Document 2). During operation of such an active matrix drive type electrophoretic display device, a plurality of scanning lines are sequentially selected for each horizontal scanning period, and a data potential is applied to the pixels corresponding to the selected scanning lines via the data lines. Supplied.

When driving the electrophoretic display device, for example, when changing the display image, the contents displayed so far are erased over the entire display area (erasing all white or all black), and then a new one is displayed. The display contents are rewritten (for example, see Patent Document 3). Specifically, by applying a voltage between the common electrode and the pixel electrode after setting all the pixel electrodes to the same potential, the contents displayed so far are erased over the entire display area, and then a new one is created. The display contents are rewritten. On the other hand, this driving method has a problem that a ghost appears in which a faint trace of the previous image remains in the display area.
On the other hand, for example, a technique for eliminating the ghost has been devised, such as lengthening or shortening the period of all white erasing or all black erasing, or performing reverse writing erasing.

JP 2006-267982 A JP 2009-109705 A JP 2002-149115 A

  However, there is a problem that the ghost cannot be completely eliminated even in the above method. In view of the circumstances as described above, an object of the present invention is to provide a driving method of an electrophoretic display device in which generation of ghost is suppressed even when a display image is rewritten at high speed.

  One aspect of the present invention for solving the above problems is a drive device for an electrophoretic display device including an electrophoretic display material and a pixel that performs display by including two electrodes that sandwich the electrophoretic display material. A driving device for an electrophoretic display device including a voltage applicator for applying an addressing pulse between two electrodes after applying a flushing pulse including the first potential and the second potential in this order between the two electrodes. is there.

  The voltage applicator may alternately repeat the first potential and the second potential in the flushing pulse. The pulse width of the first potential included in the flushing pulse may be longer than the pulse width of the second potential.

  Another aspect of the present invention is a method for driving an electrophoretic display device, which is executed by the drive device for an electrophoretic display device as described above.

According to the present invention, it is possible to provide an electrophoretic display device in which the generation of ghosts is suppressed.
Further, by applying the flushing pulse and the addressing pulse, the writing time can be shortened without impairing the optical reflectivity (L *).

It is a block diagram which shows the structure of the display part periphery of the electrophoretic display device which concerns on this invention. FIG. 3 is an equivalent circuit diagram illustrating an electrical configuration of a display unit and a pixel according to the present invention. It is a fragmentary sectional view of the display part of the electrophoretic display device which concerns on this invention. The reflection response with respect to the white display state transition by the drive method of the conventional electrophoretic display device is shown. The reflection response with respect to the black display state transition by the drive method of the conventional electrophoretic display device is shown. It is a figure which shows the basic composition of the drive voltage waveform by the drive method of the electrophoretic display device which concerns on this invention. It is a timing chart explaining the drive voltage waveform which concerns on Example 1 of this invention. It is a graph which shows the change of the reflectance at the time of rewriting "from white to white" and "from black to white" by Example 1 of this invention. It is a graph which shows the change of the reflectance at the time of rewriting "from black to black" and "from white to black" by Example 1 of this invention. It is a timing chart explaining the drive voltage waveform which concerns on Example 2 of this invention. It is a graph which shows the change of the reflectance at the time of rewriting "from white to white" and "from black to white" by Example 2 of this invention. It is a graph which shows the change of the reflectance at the time of rewriting "from black to black" and "from white to black" by Example 2 of this invention.

  An electrophoretic display device and a driving method thereof according to the present embodiment will be described with reference to FIGS. In the following embodiments, an active matrix drive type electrophoretic display device will be described as an example of the electro-optical device according to the present embodiment.

  First, the overall configuration of the electrophoretic display device according to the present embodiment will be described with reference to FIGS. 1 to 3.

  FIG. 1 is a block diagram illustrating a configuration around a display unit of an electrophoretic display device 1 according to the present embodiment.

  In FIG. 1, an electrophoretic display device 1 according to this embodiment is an active matrix drive type electrophoretic display device, and includes a display unit 2, a controller 10, a scanning line driving circuit 60, a data line driving circuit 70, and the like. The common potential supply circuit 100 is provided.

  In the display unit 2, m rows × n columns of pixels 20 are arranged in a matrix (in a two-dimensional plane). The display unit 2 is provided with m scanning lines 40 (Y1, Y2,..., Ym) and n data lines 50 (X1, X2,..., Xn) intersecting each other. Yes. Specifically, the m scanning lines 40 extend in the row direction (that is, the X direction), and the n data lines 50 extend in the column direction (that is, the Y direction). The pixels 20 are arranged corresponding to the intersections of the m scanning lines 40 and the n data lines 50.

  The controller 10 controls operations of the scanning line driving circuit 60, the data line driving circuit 70, and the common potential supply circuit 100. For example, the controller 10 supplies timing signals such as a clock signal and a start pulse to each circuit.

  The scanning line driving circuit 60 sequentially supplies a scanning signal in a pulsed manner to each of the scanning lines Y1, Y2,..., Ym during a predetermined frame period under the control of the controller 10.

  The data line driving circuit 70 supplies a data potential to the data lines X1, X2,..., Xn under the control of the controller 10. The data potential is any one of a reference potential GND (for example, 0 V), a high potential VSH (for example, +15 V), or a low potential -VSH (for example, -15 V).

  The common potential supply circuit 100 supplies a common potential Vcom (in this embodiment, the same potential as the reference potential GND) to the common potential line 90. Note that the common potential Vcom is a range in which no voltage is substantially generated between the counter electrode 22 (see FIG. 2) supplied with the common potential Vcom and the pixel electrode 21 (see FIG. 2) supplied with the reference potential GND. Of these, a potential different from the reference potential GND may be used. For example, the common potential Vcom may be a value different from the reference potential GND supplied to the pixel electrode 21 in consideration of fluctuations in the potential of the pixel electrode 21 due to feedthrough. In this specification, it is assumed that the common potential Vcom and the reference potential GND are the same.

  Here, the feed-through means that when the scanning signal is supplied to the scanning line 40 after the scanning signal is supplied to the scanning line 40 and the potential is supplied to the pixel electrode 21 via the data line 50 (for example, This refers to a phenomenon in which the potential of the pixel electrode 21 fluctuates due to parasitic capacitance with the scanning line 40 (for example, decreases with a decrease in the potential of the scanning line 40). The common potential Vcom may have a value slightly lower than the reference potential GND supplied to the pixel electrode 21 on the assumption that the potential of the pixel electrode 21 is lowered by feedthrough in advance. The potential Vcom and the reference potential GND are considered to be the same potential.

  Note that various signals are input to and output from the controller 10, the scanning line driving circuit 60, the data line driving circuit 70, and the common potential supply circuit 100, but descriptions of those that are not particularly related to the present embodiment are omitted. .

  FIG. 2 is an equivalent circuit diagram showing an electrical configuration of the pixel 20 according to the present embodiment.

  In FIG. 2, the pixel 20 includes a pixel switching transistor 24, a pixel electrode 21, a counter electrode 22, an electrophoretic element 23, and a storage capacitor 27.

  The pixel switching transistor 24 is composed of, for example, an N-type transistor. The pixel switching transistor 24 has a gate electrically connected to the scanning line 40, a source electrically connected to the data line 50, and a drain electrically connected to the pixel electrode 21 and the storage capacitor 27. It is connected to the. The pixel switching transistor 24 is configured to pulse the data potential supplied from the data line driving circuit 70 (see FIG. 1) via the data line 50 via the scanning line 40 from the scanning line driving circuit 60 (see FIG. 1). Are output to the pixel electrode 21 and the storage capacitor 27 at a timing corresponding to the scanning signal supplied to the pixel.

  A data potential is supplied to the pixel electrode 21 from the data line driving circuit 70 via the data line 50 and the pixel switching transistor 24. The pixel electrode 21 is disposed so as to face the counter electrode 22 via the electrophoretic element 23.

  The counter electrode 22 is electrically connected to a common potential line 90 to which a common potential Vcom is supplied.

  The electrophoretic element 23 is composed of a plurality of microcapsules 80 (see FIG. 3) that form electrophoretic display materials each containing electrophoretic particles.

  The storage capacitor 27 is composed of a pair of electrodes arranged opposite to each other with a dielectric film therebetween, one electrode is electrically connected to the pixel electrode 21 and the pixel switching transistor 24, and the other electrode is a common potential line 90. Is electrically connected. The storage capacitor 27 can maintain the data potential for a certain period.

  Next, a specific configuration of the display unit of the electrophoretic display device according to the present embodiment will be described with reference to FIG.

  FIG. 3 is a partial cross-sectional view of the display unit 2 of the electrophoretic display device 1 according to this embodiment.

  In FIG. 3, the pixel 20 has a configuration in which a microcapsule 80 is sandwiched between a TFT substrate 28 and a counter substrate 29. In the present embodiment, description will be made on the assumption that an image is displayed on the counter substrate 29 side.

  The TFT substrate 28 is a substrate made of, for example, glass or plastic. Although not shown here, the pixel switching transistor 24, the storage capacitor 27, the scanning line 40, the data line 50, the common potential line 90, and the like described above with reference to FIG. 2 are formed on the TFT substrate 28. A laminated structure is formed. A plurality of pixel electrodes 21 are provided in a matrix on the upper layer side of the stacked structure.

  The counter substrate 29 is a transparent substrate made of, for example, glass or plastic. On the surface of the counter substrate 29 facing the TFT substrate 28, the counter electrode 22 is formed in a solid shape so as to face the plurality of pixel electrodes 21. The counter electrode 22 is made of a transparent conductive material such as magnesium silver (MgAg), indium / tin oxide (ITO), indium / zinc oxide (IZO).

  The electrophoretic element 23 is composed of a plurality of microcapsules 80 each containing electrophoretic particles, and is fixed between the TFT substrate 28 and the counter substrate 29 by a binder 30 and an adhesive layer 31 made of, for example, resin. . In the display unit 2 according to the present embodiment, in the manufacturing process, an electrophoretic sheet in which the electrophoretic element 23 is previously fixed to the counter substrate 29 side by the binder 30 is formed with a separately manufactured pixel electrode 21 and the like. The TFT substrate 28 is bonded to an adhesive layer 31.

  One or a plurality of microcapsules 80 are sandwiched between the pixel electrode 21 and the counter electrode 22, and are arranged in one pixel 20 (in other words, with respect to one pixel electrode 21).

  The microcapsule 80 is formed by enclosing a dispersion medium 81, a plurality of white particles 82, and a plurality of black particles 83 inside a coating 85. The microcapsule 80 is formed in a spherical shape having a particle size of about 50 μm, for example.

  The coating 85 functions as an outer shell of the microcapsule 80 and is formed of a translucent polymer resin such as acrylic resin such as polymethyl methacrylate and polyethyl methacrylate, urea resin, gum arabic, and gelatin. .

  The dispersion medium 81 is a medium for dispersing the white particles 82 and the black particles 83 in the microcapsules 80 (in other words, in the coating 85). Examples of the dispersion medium 81 include water, alcohol solvents such as methanol, ethanol, isopropanol, butanol, octanol, and methyl cellosolve, various esters such as ethyl acetate and butyl acetate, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. , Aliphatic hydrocarbons such as pentane, hexane and octane, alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecyl Aromatic hydrocarbons such as benzenes with long chain alkyl groups such as benzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, etc., halo such as methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, etc. Emissions of hydrocarbons, carboxylate or other oils may be used singly or as a mixture. In addition, a surfactant may be added to the dispersion medium 81.

  The white particles 82 are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white (zinc oxide), and antimony trioxide, and are negatively charged, for example.

  The black particles 83 are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are positively charged, for example.

  For this reason, the white particles 82 and the black particles 83 can move in the dispersion medium 81 by the electric field generated by the potential difference between the pixel electrode 21 and the counter electrode 22.

  These pigments include electrolytes, surfactants, metal soaps, resins, rubbers, oils, varnishes, charge control agents composed of particles such as compounds, titanium-based coupling agents, aluminum-based coupling agents, silanes as necessary. A dispersant such as a system coupling agent, a lubricant, a stabilizer, and the like can be added.

  In FIG. 3, when a voltage is applied between the pixel electrode 21 and the counter electrode 22 so that the potential of the counter electrode 22 is relatively high, the positively charged black particles 83 are caused by Coulomb force. While attracted to the pixel electrode 21 side in the microcapsule 80, the negatively charged white particles 82 are attracted to the counter electrode 22 side in the microcapsule 80 by the Coulomb force. As a result, the white particles 82 gather on the display surface side (that is, the counter electrode 22 side) in the microcapsule 80, and the color of the white particles 82 (that is, white) is displayed on the display surface of the display unit 2. Will be displayed. Conversely, when a voltage is applied between the pixel electrode 21 and the counter electrode 22 so that the potential of the pixel electrode 21 becomes relatively high, the negatively charged white particles 82 are generated by the Coulomb force. While attracted to the electrode 21 side, the positively charged black particles 83 are attracted to the counter electrode 22 side by Coulomb force. As a result, the black particles 83 are collected on the display surface side of the microcapsule 80, and the color (that is, black) of the black particles 83 is displayed on the display surface of the display unit 2.

  In addition, red, green, blue, etc. can be displayed by replacing the pigment used for the white particle 82 and the black particle 83 with pigments, such as red, green, and blue, for example.

  4 and 5 show respective pulse widths and reflection responses to the transition of the white and black states in the conventional driving method of the electrophoretic display device, and the reason why the ghost is generated will be described. In essence, a ghost is a lightness error between two transition states due to the limited resolution of the pulse width. As shown in FIGS. 4 and 5, the width of one frame is the minimum unit of each pulse width, and is limited by the frame rate (ft) of the display.

  Next, an operation at the time of image rewriting (writing) in the electrophoretic display device 1 according to the present embodiment, that is, a driving method of the electrophoretic display device 1 will be described with reference to FIGS. Hereinafter, for convenience of description, the operation at the time of rewriting will be described by focusing on one pixel to be rewritten. In addition, although each process shown below is typically performed by the voltage applicator controlled by the controller 10, it may be controlled by other than the controller 10. In addition, the voltage applicator is appropriately realized in various modes by the above-described components and other means.

  FIG. 6 is a diagram showing a basic configuration (driving voltage waveform) of the driving method of the electrophoretic display device 1 according to the present invention.

  The image writing period is composed of two periods. The first half is called the flushing pulse period and the second half is called the addressing pulse period. By providing these two different pulse periods, it is possible to set in consideration of the balance of the final optical reflectivity (L *) before and after writing, that is, ghost reduction.

  The flushing pulse is composed of two periods, a period for applying the first potential (pulse width) (hereinafter referred to as T1) and a period for applying the second potential (hereinafter referred to as T2). This is a period during which the inverted potential of the image is applied, and T2 is a period during which the same potential as that of the previous image is applied. Further, it is preferable to change the ratio (that is, the duty ratio) between the periods T1 and T2 in accordance with the frame rate (ft).

  The period of the flushing pulse has an auxiliary role of resetting the previous image and separating the white particles and black particles so that the display state does not reach black or any intermediate state that does not reach white. In this flushing pulse, when the pulse widths of the two periods (T1 and T2) (that is, the period for applying the inverted potential of the previous image and the period for applying the same potential as the previous image) are the same and the display colors before and after rewriting are different, When the display color before and after rewriting is the same as the state of “white does not become white” or “black does not become black”, there arises a problem that “white becomes white” or “black becomes black”. Further, when the pulse width of T2 (that is, the period during which the same potential as the previous image is applied) is longer than the pulse width of T1, and the display color before and after rewriting is the same, “white becomes whiter” or “black becomes blacker”. When the display colors before and after rewriting are different from each other, the problem that “white does not become white” or “black does not become black” occurs. Due to the lightness error between these two transition states, a faint trace of the previous image remains and a ghost appears. On the other hand, when the pulse width of T1 (that is, the period during which the inverted potential of the previous image is applied) is longer than the pulse width of T2, the difference in brightness between the two transition states is minimal when the display colors before and after rewriting are the same or different. (Invisible level), and ghost is reduced.

  Further, the ratio of T1 and T2 in the flushing pulse period is such that T2 is 1 and T1 is larger than 1, and the range T1: T2 is preferably 2: 1 to 10: 1, particularly 2: 1 to 5: 1. More preferred. Further, T1 and T2 may be repeated a plurality of times during the flushing pulse period.

  The addressing pulse is a voltage pulse having a time width of a predetermined write pulse. This voltage pulse is the potential of the final written image, and its application method may be a single potential or a bipolar potential consisting of positive and negative voltage pulses.

Example 1
In the first embodiment of the present invention, an operation example when the frame rate (ft) is 40 ms, the total image writing time is 480 ms, and the ratio T1: T2 of the flushing pulse period is 2: 1 will be described. The configuration of the display device shown in this embodiment is realized by the configuration of a block diagram, an equivalent circuit, and a cross-sectional view, and thus description of the configuration is omitted.

  FIG. 7 is a timing chart illustrating drive voltage waveforms according to the first embodiment of the present invention.

From top to bottom,
(1) From white display to white display (2) From black display to white display (3) From black display to black display (4) The display state is changed (transitioned) into four patterns from white display to black display. It is a drive voltage waveform sometimes applied.

  First, when changing from white display to white display, the potential of the flushing pulse period T1 is set to VSH, T1 is set to 80 ms, the potential of T2 is set to −VSH, and T2 is set to 40 ms. After applying the flushing pulse three times, the potential (white display) -VSH of the final written image is applied for 120 ms during the addressing pulse period.

  Next, when changing from black display to white display, the potential of the flushing pulse period T1 is set to −VSH, T1 is set to 80 ms, the potential of T2 is set to VSH, and T2 is set to 40 ms. After this flushing pulse is applied once, the potential (white display) -VSH of the final written image is applied for 360 ms during the addressing pulse period.

  FIG. 8 is a graph showing changes in optical reflectance (L *) when rewriting “from white display to white display” and “from black display to white display”.

  In FIG. 8, “from white display to white display” is indicated by a thick line, and “from black display to white display” is indicated by a thin line. When rewriting both images, by adjusting the number of times of application of the flushing pulse period, that is, an intermediate region where the display state does not reach black or white is arbitrarily created, and the addressing pulse applied next to the flushing pulse By adjusting this, it is possible to achieve both of the final optical reflectivities (L *) of both, and it is possible to improve white ghost.

  Next, when changing from black display to black display, the potential of the flushing pulse period T1 is set to −VSH, T1 is set to 80 ms, the potential of T2 is set to VSH, and T2 is set to 40 ms. After this flushing pulse is applied twice, the reverse potential (white display) -VSH of the final written image is applied for 160 ms during the addressing pulse period, and then the potential (black display) VSH of the final written image is applied for 80 ms.

  Next, when changing from white display to black display, the potential of the flushing pulse period T1 is VSH, T1 is 80 ms, the potential of T2 is −VSH, and T2 is 40 ms. After this flushing pulse is applied once, the potential (black display) VSH of the final written image is applied for 360 ms during the addressing pulse period.

  FIG. 9 is a graph showing changes in the optical reflectance (L *) when rewriting “from black display to black display” and “from white display to black display”.

  In FIG. 9, “from black display to black display” is indicated by a thick line, and “from white display to black display” is indicated by a thin line. When rewriting both images, by adjusting the number of times of application of the flushing pulse period, that is, an intermediate region where the display state does not reach black or white is arbitrarily created, and the addressing pulse applied next to the flushing pulse Is not a single potential, but a bipolar potential consisting of positive and negative voltage pulses, and by adjusting the application time of both polarities, both the final optical reflectivity (L *) is achieved, Improves black ghost improvement.

(Example 2)
In the second embodiment of the present invention, an operation example when the frame rate (ft) is 10 ms, the total image writing time is 600 ms, and the ratio T1: T2 of the flushing pulse period is 4: 1 will be described. In addition, since it implement | achieves by the structure of the block diagram of the display apparatus shown by this embodiment, an equivalent circuit, and sectional drawing similarly to Example 1, description of a structure is abbreviate | omitted.

  FIG. 10 is a timing chart illustrating drive voltage waveforms according to the second embodiment of the present invention.

From top to bottom,
(1) From white display to white display (2) From black display to white display (3) From black display to black display (4) The display state is changed (transitioned) into four patterns from white display to black display. It is a drive voltage waveform sometimes applied.

  First, when changing from white display to white display, the potential of the flushing pulse period T1 is VSH, T1 is 40 ms, the potential of T2 is −VSH, and T2 is 10 ms. After applying the flushing pulse seven times, the potential (white display) -VSH of the final written image is applied for 250 ms during the addressing pulse period.

  Next, when changing from black display to white display, the potential of the flushing pulse period T1 is set to −VSH, T1 is set to 40 ms, the potential of T2 is set to VSH, and T2 is set to 10 ms. After applying the flushing pulse seven times, the potential of the last written image (white display) -VSH is applied for 250 ms during the addressing pulse period.

  FIG. 11 is a graph showing changes in the optical reflectance (L *) when rewriting “from white display to white display” and “from black display to white display”.

  In FIG. 11, “from white display to white display” is indicated by a thick line, and “from black display to white display” is indicated by a thin line. When rewriting both images, by adjusting the number of times of application of the flushing pulse period, that is, an intermediate region where the display state does not reach black or white is arbitrarily created, and the addressing pulse applied next to the flushing pulse By adjusting this, it is possible to achieve both of the final optical reflectivities (L *) of both, and it is possible to improve white ghost.

  Next, when changing from black display to black display, the potential of the flushing pulse period T1 is set to -VSH, T1 is set to 40 ms, the potential of T2 is set to VSH, and T2 is set to 10 ms. After applying the flushing pulse seven times, the potential (black display) VSH of the final written image is applied for 250 ms during the addressing pulse period.

  Next, when changing from white display to black display, the potential of the flushing pulse period T1 is VSH, T1 is 40 ms, the potential of T2 is −VSH, and T2 is 10 ms. After applying the flushing pulse seven times, the potential (black display) VSH of the final written image is applied for 250 ms during the addressing pulse period.

  FIG. 12 is a graph showing changes in the optical reflectance (L *) when rewriting “from black display to black display” and “from white display to black display”.

  In FIG. 12, “from black display to black display” is indicated by a thick line, and “from white display to black display” is indicated by a thin line. When rewriting both images, by adjusting the number of times of application of the flushing pulse period, that is, an intermediate region where the display state does not reach black or white is arbitrarily created, and the addressing pulse applied next to the flushing pulse By adjusting this, it is possible to achieve a balance between the final optical reflectivities (L *) of both, and it is possible to improve black ghost.

  As described above, according to the driving method of the electrophoretic display device according to the present embodiment, the distribution positions (halftones) of both white and black charged particles are adjusted by adjusting the duty ratio of the flushing pulse and the voltage application time. ) Is arbitrarily determined, the voltage of the addressing pulse applied next to the flushing pulse is set to a single or bipolar potential, and the quantization error can be adjusted by adjusting the voltage application time. Therefore, according to the present invention, high-speed writing and ghost reduction can be achieved by applying the flushing pulse prior to the application of the addressing pulse.

  For example, the present invention can be applied to a segment type electrophoretic display panel. The operation of the segment type electrophoretic display panel is the same as the operation described with reference to FIGS. 1 to 12 except that the pixel electrode is replaced with the segment electrode, and when the active matrix type electrophoretic display panel is used. Has the same effect as.

  Although the case where positively charged black particles and negatively charged white particles are used as the electrophoretic particles in the embodiment of the present invention has been described, negatively charged black particles and positively charged white particles are used. Also good.

  In addition, the electrophoretic display device is not limited to one that performs black and white two-particle electrophoresis using black particles and white particles, and may perform one-particle electrophoresis such as blue and white, or a combination other than black and white It doesn't matter.

  The driving method according to the present invention may be applied not only to the electrophoretic display device but also to a memory-type display unit. For example, ECD (Electrochromic Display = electrochromic display).

DESCRIPTION OF SYMBOLS 1 Electrophoretic display device 2 Display part 10 Controller (drive device of electrophoretic display device 1)
20 pixels 21 pixel electrodes 22 counter electrodes 23 electrophoretic elements 24 pixel switching transistors 27 holding capacitors 28 TFT substrates 29 counter substrates 30 binders 31 adhesive layers 40 scanning lines 50 data lines 60 scanning line driving circuits 70 data line driving circuits 80 microcapsules (Electrophoretic display material)
81 Dispersion medium 82 White particles 83 Black particles 85 Coating 90 Common potential line 100 Common potential supply circuit

Claims (6)

A drive device for an electrophoretic display device including an electrophoretic display material and a pixel that performs display with two electrodes sandwiching the electrophoretic display material,
Driving an electrophoretic display device including a voltage applicator that applies an addressing pulse between the two electrodes after applying a flushing pulse including the first potential and the second potential in this order between the two electrodes. apparatus.   The electrophoretic display device drive device according to claim 1, wherein the voltage applicator alternately repeats the first potential and the second potential in the flushing pulse.   The drive device of the electrophoretic display device according to claim 1, wherein a pulse width of the first potential included in the flushing pulse is longer than a pulse width of the second potential. A driving method of an electrophoretic display device including an electrophoretic display material and a pixel that performs display by having two electrodes sandwiching the electrophoretic display material,
A method for driving an electrophoretic display device, comprising: applying a flushing pulse including a first potential and a second potential in this order between the two electrodes, and then applying an addressing pulse between the two electrodes.   The method for driving an electrophoretic display device according to claim 4, wherein the first potential and the second potential are alternately and repeatedly applied as the flushing pulse. 6. The method of driving an electrophoretic display device according to claim 4, wherein a pulse width of the first potential included in the flushing pulse is longer than a pulse width of the second potential.

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