JP2009053719A - Method for driving electrophoretic display, electrophoretic display and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drive an active matrix electrophoretic display. <P>SOLUTION: In a resetting period Tr, a reset voltage is applied to each pixel electrode. Next in a writing period, a voltage is applied to each pixel electrode in a period corresponding to a grayscale value designated by the image data. Subsequently a common electrode voltage is applied to each pixel electrode, in order to discharge electricity which is accumulated in the pixel capacitor away, applying no electric field to a dispersal system. Then a displayed image is held. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophoretic display device having a dispersion system containing electrophoretic particles, a driving method thereof, a driving circuit, and an electronic apparatus.

  As a non-luminous display device, an electrophoretic display device using an electrophoretic phenomenon is known. The electrophoresis phenomenon is a phenomenon in which fine particles move when an electric field is applied to a dispersion system in which fine particles (electrophoretic particles) are dispersed in a liquid (dispersion medium). Basically, an electrophoretic display device has a pair of electrodes opposed to each other at a predetermined interval, and a dispersion system sealed between these electrodes. When a potential difference is applied between the two electrodes, the charged electrophoretic particles are attracted to one of the electrodes depending on the direction of the electric field. Here, if the dispersion medium is dyed with a dye and the electrophoretic particles are composed of pigment particles, the observer can see the color of the electrophoretic particles or the color of the dye.

  However, there is no conventional example of an active matrix type electrophoretic display device, and its driving method and driving circuit are not known.

  The present invention has been made in view of the above-described circumstances, and an object thereof is an electrophoretic display device that realizes a desired gradation display, in particular, a driving method, a drive circuit, and an electronic device for an active matrix type electrophoretic display device. To provide equipment.

  To achieve the above object, the present invention includes a common electrode, a plurality of pixels, and a plurality of switching elements connected to each pixel, and each of the plurality of pixels is connected to one of the switching elements. The electrophoretic device driving method includes: a pixel electrode facing the common electrode at a distance; and a dispersion system sandwiched between the common electrode and the pixel electrode and containing electrophoretic particles. A second voltage for applying the first voltage to the common electrode and moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between the pixel electrode and the common electrode in a predetermined time. And performing a writing operation of applying the second voltage to the pixel electrode through the switching element for the predetermined time, and then applying the first voltage to the pixel electrode through the switching element. mark To provide a driving method of the electrophoretic display device and performs no bias operation of.

  According to the present invention, when the second voltage is supplied to the pixel electrode, an electric field is applied to the dispersion system, and the clonal force acts on the electrophoretic particles to change the spatial state. Next, by supplying the first voltage to the pixel electrode, the potential difference between the electrodes becomes zero. When the switching element is turned off, the spatial state of the electrophoretic particles is fixed, and the display image represented by the spatial state of the electrophoretic particles is fixed. If the value of the second voltage is changed, the spatial distribution of the particles to be realized is also different. Therefore, a desired gradation can be displayed in each pixel by setting the value of the second voltage according to the gradation to be displayed.

  In a preferred aspect, in the voltage writing operation, a voltage corresponding to the display gradation is applied to the pixel electrode as the second voltage, and the electrophoretic particles are moved to an initial position prior to the writing operation. A reset operation for applying a reset voltage to the pixel electrode is performed.

  In a preferred aspect, the driving method according to the present invention includes a plurality of data lines, a plurality of scanning lines that intersect the plurality of data lines, a common electrode, the plurality of data lines, and the plurality of scanning lines. A plurality of pixel electrodes, which are respectively provided corresponding to the respective intersecting portions and are opposed to the common electrode with a certain gap therebetween, are sandwiched between the plurality of pixel electrodes and the common electrode, A plurality of dispersion systems each containing, and an ON / OFF switching control terminal provided for each of the intersections of the plurality of data lines and the plurality of scanning lines, and each scanning line passing through the intersection. And a plurality of switching elements that connect a data line passing through the intersection when connected to a pixel electrode provided corresponding to the intersection. A certain length of time An operation for display control using the plurality of scanning lines and the plurality of data lines is performed using a field, and in the operation for display control in one field, a common electrode voltage is applied to the common electrode. And sequentially applying the voltage to turn on all the switching elements connected to the scanning line to each of the plurality of pixels. The gradation voltage value for moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between the pixel electrode and the common electrode is determined, and the gradation voltage corresponding to each gradation voltage is determined. Applying each of the data lines to the data line for a certain period of time, applying the common electrode voltage to the plurality of data lines, and collectively switching all the switching elements connected to the scan line to the selected scan line And applying a voltage to turn off Te.

  According to this driving method, an image can be displayed in a matrix. In addition, by applying a common electrode voltage to the pixel electrodes, the potential difference between the electrodes becomes zero, so that an electric field between the electrodes is not generated. Accordingly, the spatial state of the electrophoretic particles can be fixed and a display image can be held. Further, in this driving method, the writing operation corresponding to the pixels for one horizontal scanning line can be completed within one horizontal scanning period.

  In a preferred embodiment, a reset operation and a write operation are alternately repeated using one field each, and in the field for performing the reset operation, an electric field for initializing the spatial state of the electrophoretic particles is applied. In the field for applying the voltage for generating to the plurality of data lines as the pixel voltage and performing the writing operation, the plurality of gradation voltages corresponding to the target display gradation are used as the pixel voltage. Applied to the data line. In this aspect, the number of times of voltage application for initialization and voltage application for updating the pixel voltage can be reduced.

  In another preferred embodiment, after performing the reset operation using one field, the write operation is repeated using the subsequent field, and in the field for performing the reset operation, The pixel voltage is applied to the plurality of data lines as the voltage for generating an electric field for initializing the spatial state, and the pixel voltage is obtained by the previous writing operation in the field for performing the writing operation. A difference voltage between the gradation voltage corresponding to the displayed display gradation and the gradation voltage corresponding to the target display gradation is applied to the plurality of data lines.

  In another aspect, the present invention relates to a plurality of data lines, a plurality of scanning lines that three-dimensionally intersect with the plurality of data lines, a common electrode, and each intersection of the plurality of data lines and the plurality of scanning lines. Each of the plurality of pixel electrodes facing each of the common electrodes with a certain gap therebetween, and sandwiched between the plurality of pixel electrodes and the common electrode, each containing an electrophoretic particle. A plurality of distributed systems are provided corresponding to each intersection of the plurality of data lines and the plurality of scanning lines, and each on / off switching control terminal is connected to the scanning line passing through the intersection. A driving circuit for an electrophoretic display device having a plurality of switching elements that connect data lines that pass through the intersection when being in an on state to pixel electrodes provided corresponding to the intersection, Common electrode voltage to common electrode The application unit to be applied and the scanning line are sequentially selected, and a voltage for turning on all the switching elements connected to the scanning line is applied to the selected scanning line for a certain period, and then the selection is performed. A scanning line driving unit that applies a voltage for turning off all the switching elements connected to the scanning line to the scanning line, and the pixel electrode and the common electrode with respect to each of the plurality of pixels. A voltage value for moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between each is determined, one scanning line is selected, and the switching element is connected to the scanning line. The grayscale voltage is applied to the corresponding data line for a certain period of time within a period in which the voltages to be turned on collectively are applied, and then the common electrode voltage is applied to the plurality of data lines. To provide a driving circuit of the electrophoretic display device characterized by comprising a linear drive unit.

  In a preferred aspect, the drive circuit performs a reset operation using one field and then repeats a write operation using a subsequent field. In the field for performing the reset operation, The data line driving circuit applies a plurality of pixel voltages for generating an electric field for initializing a spatial state of the electrophoretic particles to the plurality of data lines, and performs the writing operation in the data field. The line driver circuit uses, as the plurality of data, a difference voltage between a gradation voltage corresponding to a display gradation obtained by a previous writing operation and a gradation voltage corresponding to a target display gradation as the pixel voltage. Apply to the wire.

  According to another aspect of the present invention, the driving circuit, the plurality of data lines, the plurality of scanning lines, the plurality of data lines, and the switching elements provided corresponding to the intersections of the scanning lines and the data lines, An electrophoretic panel comprising a dispersion system containing electrophoretic particles sandwiched between a first substrate having each pixel electrode connected to the switching element and a second substrate having a common electrode. And an electronic apparatus using the electrophoretic display device. In this case, it is preferable that the driving circuit and the switching element are constituted by thin film transistors and these are formed by the same manufacturing process.

  The electronic apparatus according to the present invention is characterized by using an electrophoretic device as a display unit, such as an electronic book, a personal computer, a mobile phone, an electronic bulletin board, and an electronic road sign. Applicable.

  As described above, according to the present invention, a desired gradation display can be realized using the electrophoresis phenomenon.

Embodiments of the present invention will be described below with reference to the drawings.
A: First Embodiment The electrophoretic display device according to the first embodiment displays an image according to the input image signal VID, and can display both a still image and a moving image. Suitable for displaying still images.

A-1: Overall Configuration of Electrophoretic Display Device The electrophoretic display device of this embodiment includes an electrophoretic display panel and a peripheral circuit. First, the mechanical configuration of the electrophoretic display panel will be described. FIG. 1 is an exploded perspective view showing a mechanical configuration of an electrophoretic display panel A according to an embodiment of the present invention, and FIG. 2 is a partial sectional view thereof.

  As shown in FIGS. 1 and 2, an electrophoretic display panel A includes an element substrate 100 such as glass or semiconductor on which a pixel electrode 104 or the like is formed, and a counter substrate 200 on which a planar common electrode 201 or the like is formed. Have. The element substrate 100 and the counter substrate 200 are bonded to each other so that the respective electrode formation surfaces face each other with a certain gap therebetween. A space between the element substrate 100 and the counter substrate 200 is partitioned by a partition 110 having a certain height. In this example, the partition 110 is provided so as to divide pixels that are display units of an image. A space partitioned by the partition 110 is called a divided cell 11C, and the dispersion system 1 is filled therein.

  This dispersion system 1 is obtained by dispersing electrophoretic particles 3 in a dispersion medium 2. In the dispersion medium 2, additives such as a surfactant are added as necessary. In the dispersion system 1, the specific gravity of the dispersion medium 2 and the specific gravity of the electrophoretic particles 3 are selected to be approximately equal to avoid sedimentation of the electrophoretic particles 3 due to gravity.

  As described above, the partition 110 is provided with a large number of divided cells 11C, so that the region in which the electrophoretic particles 3 can migrate is limited to the inside of the divided cells 11C. In the dispersion system 1, the dispersion of particles may be biased, or agglomeration in which a plurality of particles are combined to form a large mass may occur. As described above, when the plurality of divided cells 11C are formed using the partition 110, such a phenomenon can be prevented and the quality of the display image can be improved.

  The electrophoretic display panel A is capable of full color display. In this case, three types corresponding to red, green, and blue are used as the dispersion system 1 so that each pixel can display one of the primary colors (RGB).

  First, in the dispersion system 1r corresponding to red, red particles can be used as the electrophoretic particles 3r, and cyan particles can be used as the dispersion medium 2r. For example, iron oxide can be used as the electrophoretic particles 3r. Next, in the dispersion system 1g corresponding to green, green particles can be used as the electrophoretic particles 3g, and magenta color can be used as the dispersion medium 2g. For example, cobalt green pigment particles can be used as the electrophoretic particles 3g. Next, in the dispersion system 1b corresponding to blue, blue particles can be used as the electrophoretic particles 3b, and yellow particles can be used as the dispersion medium 2b. As the electrophoretic particles 2b, for example, cobalt blue pigment particles can be used.

  That is, the electrophoretic particles 3 that reflect the display color are used, while the dispersion medium 2 that corresponds to the color that absorbs the display color (complementary color in the above example) is used. Further, members of the counter substrate 200, the common electrode 201, and the sealing material 202 are used. Therefore, if the electrophoretic particles 3 are floating on the electrode on the display surface side, the electrophoretic particles 3 reflect light having a wavelength corresponding to the display color, and the observer recognizes the color by the reflected light. On the other hand, if the electrophoretic particles 3 are settled on the electrode opposite to the display surface, the light having the wavelength corresponding to the display color is absorbed by the dispersion medium 2, so that the light having the wavelength reaches the observer. Because there is no observer, the color cannot be recognized. By the way, it is possible to control how the electrophoretic particles 3 are distributed in the thickness direction of the dispersion system 1 by the direction and intensity of the electric field applied to the dispersion system 1. Therefore, the reflection intensity of the light reflected by the electrophoretic particles 3 can be adjusted by using the electrophoretic particles 3 in combination with the dispersion medium 2 that absorbs the reflected light and controlling the electric field intensity. It is possible to change the intensity of light reaching the beam.

  Next, a display area A1 and a peripheral area A2 are provided on the surface of the element substrate 100. The display area A1 is partitioned by a partition 110, and in addition to the pixel electrode 104, a thin film transistor (hereinafter referred to as TFT) that functions as a scanning line, a data line, and a switching element, which will be described later. ) Is formed. On the other hand, a scanning line driving circuit, a data line driving circuit, and external connection electrodes, which will be described later, are formed in the peripheral region A2 of the element substrate 100.

  FIG. 3 is a block diagram showing an electrical configuration of the electrophoretic display device. As shown in this figure, the electrophoretic display device includes an electrophoretic display panel A, an image signal processing circuit 300A and a timing generator 400 which are peripheral circuits thereof. Here, the image signal processing circuit 300A performs a correction process on the input image signal VID according to the electrical characteristics of the electrophoretic display panel A to generate and output image data D, and outputs the image data D. Before, the reset data Drest is output for a predetermined period. The reset data Drest is used to attract the electrophoretic particles 3 migrating in the dispersion system 1 to the pixel electrode 104 side and initialize the spatial state thereof. Hereinafter, in order to simplify the explanation, it is assumed that the dispersion medium 2 of the dispersion system 1 is colored black, and the electrophoretic particles 3 are white particles such as titanium oxide and are positively charged.

  The timing generator 400 generates various timing signals for controlling the scanning line driving circuit 130 and the data line driving circuit 140A only when the image data D is output from the image signal processing circuit 300A.

  In the display area A1 of the element substrate 100, a plurality of scanning lines 101 are formed in parallel along the X direction, and a plurality of data lines 102 are formed in parallel along the Y direction orthogonal thereto. Yes. At each intersection of the scanning line 101 and the data line 102, the gate electrode of the TFT 103 is connected to the scanning line 101, the source electrode is connected to the data line 102, and the drain electrode is connected to the pixel. It is connected to the electrode 104. Each pixel includes a pixel electrode 104, a common electrode 201 formed on the counter substrate 200, and a dispersion system 1 sandwiched between these electrodes (see FIG. 2). That is, each pixel is arranged in a matrix corresponding to the intersection of the scanning line 101 and the data line 102. Note that the scanning line driving circuit 130 and the data line driving circuit 140A are configured by using TFTs, and are formed by a manufacturing process common to the TFT 103 of the pixel. This is advantageous in terms of integration and manufacturing costs.

  In such an electrophoretic display panel A, when a certain scanning line signal Yj becomes active, the TFT 103 of the jth scanning line 101 to which the scanning line signal Yj is supplied is turned on, and the data line signals X1, X2,. , Xn are supplied to the pixel electrode 104. On the other hand, the common electrode voltage Vcom is applied to the common electrode 201 of the counter substrate 200 from a power supply circuit (application unit) (not shown). As a result, a potential difference is generated between the pixel electrode 104 and the common electrode 201, and the electrophoretic particles 3 of the dispersion system 1 migrate to display a gradation corresponding to the image data D for each pixel. .

A-2: Display Principle Next, the principle of gradation display will be described. FIG. 4 is a cross-sectional view showing a simplified structure of the divided cell. In the electrophoretic display device of this example, first, a reset operation is performed. In this reset operation, the electrophoretic particles 3 are attracted to the pixel electrode 104 side. When using positively charged electrophoretic particles 3, a negative voltage is applied to the pixel electrode 104 with reference to the voltage of the common electrode 201. As a result, the electrophoretic particles 3 are attracted to the electrode 104 as shown in FIG.

  Next, as shown in FIG. 4B, a positive voltage corresponding to the gradation to be displayed is applied between the electrodes. Then, the electrophoretic particles 3 move to the common electrode 201 side by the electric field. When the potential difference is zero, the electric field stops working, and thus the electrophoretic particles 3 are stopped by the viscous resistance of the dispersion medium 2. In this case, since the moving speed of the electrophoretic particles 3 is determined according to the electric field strength, that is, the applied voltage, the moving distance is determined according to the applied voltage and the applied time. Therefore, if the application time is made constant, the position of the electrophoretic particles 3 in the thickness direction can be controlled by adjusting the applied voltage.

  Light incident from the common electrode 201 side is reflected by the electrophoretic particles 3, and this reflected light passes through the common electrode 201 and reaches the eyes of the observer. Incident light and reflected light are absorbed by the dispersion medium 2, and the degree of absorption is proportional to the optical path length. Therefore, the gradation recognized by the observer is determined by the position of the electrophoretic particle 3. As described above, when the application time is constant, the position in the thickness direction of the electrophoretic particles 3 is determined according to the applied voltage. Therefore, if a voltage corresponding to the gradation to be displayed is applied, a desired gradation display is performed. Can be obtained.

  By the way, the dispersion system 1 includes a large number of electrophoretic particles 3. Here, if the particle characteristics such as electrical characteristics (for example, charge amount) and mechanical characteristics (for example, particle diameter, weight) are uniform, the moving speed of all particles is constant, The electrophoretic particles 3 behave in the same way.

  However, since the thickness of the divided cell is several μm to several tens of μm and the maximum moving distance is extremely short, it is necessary to control a minute moving distance in order to increase the number of gradations. For this reason, the applied voltage for one gradation becomes extremely small, and gradation control becomes difficult.

  Therefore, in the present embodiment, the particle characteristics of the numerous electrophoretic particles 3 included in the dispersion system 1 are varied. If the particle characteristics are varied, the position of the electrophoretic particles 3 is broadened when a certain voltage is applied for a certain time. FIG. 5 is a graph showing an example of the relationship between the voltage between the electrodes and the gradation density. This example simulates the case where the average value of the applied voltage at which the electrophoretic particles 3 reach the common electrode 201 is 5 V and the standard deviation of the applied voltage required to reach the voltage is 0.2 V with an application time of 50 msec. It is a thing.

  In the figure, the solid line indicates the gradation characteristics with respect to the applied voltage, and the dotted line indicates the probability density with respect to the applied voltage. Here, the probability density is obtained by normalizing the number of electrophoretic particles 3 reaching the common electrode 201 with an average value of 5V.

  As shown in this figure, when the applied voltage is 4.5V or less, the electrophoretic particles 3 hardly reach the common electrode 201, but when the applied voltage is 5V, half of the electrophoretic particles 3 are common. When the voltage reaches the electrode 201 and the applied voltage is 5.5 V or more, most of the electrophoretic particles 3 reach the common electrode 201. Therefore, if the applied voltage value is controlled between 4.5V and 5.5V according to the gradation to be displayed, a desired gradation display can be performed.

A-3: Drive Circuit Next, a drive circuit that drives the scanning lines 101 and the data lines 102 will be described. First, the scanning line driving circuit 130 shown in FIG. 3 has a shift register (not shown), and starts the vertical scanning period based on the Y clock signal YCK from the timing generator 400 and its inverted Y clock YCKB. The Y transfer start pulse DY that becomes active at is sequentially shifted to generate the scanning line signals Y1, Y2,. As a result, as shown in FIG. 7, scanning line signals Y1, Y2,..., Ym in which the active period (H level period) is sequentially shifted are generated and output to each scanning line 101.

  Next, the data line driving circuit 140A will be described. FIG. 6 is a block diagram of the data line driving circuit 140A. As shown in the figure, the data line driving circuit 140A includes an X shift register 141, a bus BUS to which 6-bit image data D is supplied, switches SW1 to SWn, a first latch 142, a second latch 143, a selection circuit 144, And a D / A converter 145.

  First, the X shift register 141 sequentially generates the sampling pulses SR1, SR2,..., SRn (see FIG. 7) by sequentially shifting the X transfer start pulse DX in accordance with the X clock XCK and the inverted X clock XCKB. ing.

  Next, the bus BUS is connected to each latch of the first latch group 142 via the switches SW1 to SWn, and sampling pulses SR1, SR2,..., SRn are connected to the control input terminals of the switches SW1 to SWn. It comes to be supplied. One switch SWj has a set of six corresponding to the 6-bit image data D. Therefore, the image data D is simultaneously captured by the first latch 142 in synchronization with the sampling pulses SR1, SR2,.

  Next, the first latch 142 latches the image data D supplied from the switches SW1 to SWn and outputs them as dot sequential image data Da1 to Dan. The second latch 143 latches each point sequential image data Da1 to Dan of the first latch 142 by a latch pulse LAT. Here, the latch pulse LAT is a signal that becomes active every horizontal scanning period. Therefore, the second latch 143 generates line sequential image data Db1 to Dbn from the dot sequential image data Da1 to Dan.

  Next, the selection circuit 144 is supplied with the common voltage data Dcom generated by the image signal processing circuit 300A and the non-biased timing signal Cb generated by the timing generator 400. Here, the common voltage data Dcom is data indicating a voltage value (for example, ground level) supplied to the common electrode 201. Further, as shown in FIG. 7, the no-bias timing signal Cb is a signal that becomes active (H level) in the period from the middle to the end of one horizontal scanning period. The selection circuit 144 selects the common voltage data Dcom while the no-bias timing signal Cb is active, and selects the line-sequential image data Db1 to Dbn and outputs the data Dc1 to Dcn shown in FIG. Output.

  The D / A converter 145 converts the 6-bit data Dc1 to Dcn from digital signals to analog signals, generates the data line signals X1 to Xn, and supplies them to the data lines 102.

A-4: Operation of Electrophoretic Display Device Next, the operation of the electrophoretic display device will be described. FIG. 8 is a timing chart showing output data of the image signal processing circuit 300A. The outline of the operation will be described with reference to this figure.

  First, when the power source of the electrophoretic display device is switched from the off state to the on state at time t0, power is supplied to the image signal processing circuit 300A, the timing generator 400, and the electrophoretic display panel A. The image signal processing circuit 300A outputs the reset data Drest for one field period at time t1 when the predetermined period has elapsed and the circuit operation is stable. In the reset period Tr, as described in the display principle, the electrophoretic particles 3 are attracted to the pixel electrode 104 side, and the spatial state thereof is initialized. Although details will be described later, the data line driving circuit 140A outputs a reset voltage Vrest corresponding to the data value of the reset data Drest to each data line 102, while the scanning line driving circuit 130 sequentially selects each scanning line 101. Thus, a voltage is supplied to the pixel electrode 104, and the reset voltage Vrest is applied between all the pixel electrodes 104 and the common electrode 201.

  Next, when the time t2 is reached, the writing period Tw starts. In the writing period Tw, the image signal processing circuit 300A outputs the image data D over one field period. A gradation voltage V corresponding to the gradation to be displayed is written in each pixel electrode 104, and one display screen is completed.

  Next, the holding period Th from time t3 to time t4 is a period for holding the image written in the immediately preceding writing period Tw, and the length thereof can be arbitrarily set. In this period, the image signal processing circuit 300A stops operating and does not output data, and an electric field is not generated between the pixel electrode 104 and the common electrode 201. If there is no electric field, the electrophoretic particles 3 have no change in the spatial state. Therefore, a still image is displayed during the period.

  Next, the period from time t4 to time t6 is a period for rewriting an image, and a reset operation and a writing operation are performed as in the period from time t1 to time t3. Thereby, the display screen can be updated.

(1) Reset Operation Next, the reset operation will be described in detail. FIG. 9 is a timing chart of the electrophoretic display device in the reset operation. As described above, during the reset period Tr, the reset data Drest is supplied to the data line driving circuit 140A. Further, since the no-bias timing signal Cb becomes inactive (L level) as shown in FIG. 9, the voltage of the data line signals X1 to Xn becomes the reset voltage Vrest.

  In this example, since the electrophoretic particles 3 are charged with a positive charge, the reset voltage Vrest takes a negative value around the common electrode voltage Vcom. Here, when the scanning line signal Y 1 becomes active (H level), the TFT 103 in the first row is turned on, and the reset voltage Vrest is written to each pixel electrode 104. Thereafter, the reset voltage Vrest is applied to each pixel electrode 104 in the second row, the third row,..., The m-th row. For example, when the scanning line signal Y1 changes from active to inactive at time tx, each TFT 103 in the first row is turned off, and the pixel electrode 104 and the data line 102 are disconnected. However, since the pixel capacitance is formed by the pixel electrode 104, the dispersion system 1, and the common electrode 201, the reset voltage Vrest is not generated between the pixel electrode 104 and the common electrode 201 in the first row even when the TFT 103 is turned off. Maintained. When the reset voltage Vrest is thus applied between the electrodes, the electrophoretic particles 3 in the dispersion system 1 are attracted to the pixel electrode 104, and the spatial state thereof is initialized.

(2) Write Operation Next, the write operation will be described in detail. FIG. 10 is a timing chart of the electrophoretic display device in the writing operation. Here, the writing operation in the pixels of i row (i th scanning line) and j column (j th data line) will be described, but it goes without saying that the same writing is performed in other pixels. In the following description, the pixel in i row and j column is expressed as Pij, the gradation voltage indicating the gradation to be displayed on the pixel Pij is expressed as Vij, and the luminance of the pixel Pij is expressed as Iij.

  Since the data line signals X1 to Xn are generated by D / A converting the data Dc1 to Dcn shown in FIG. 7, the voltage of the data line signal Xj supplied to the jth data line 102 is as shown in FIG. As shown, the grayscale voltage Vij is obtained in the grayscale voltage application period Tv from time T1 to time T2, while the common electrode voltage Vcom is obtained in the non-biased period Tb from time 2 to time T3.

  Further, the scanning line signal Yi supplied to the i-th scanning line 101 becomes active during the i-th horizontal scanning period, and during this time, the TFT 103 constituting the pixel Pij is turned on. During the period from the time T1 to the time T2 in the i-th horizontal scanning period, the data line signal Xj (that is, the gradation voltage Vij) is applied to the pixel electrode 104 of the pixel Pij, and from the time T2 to the time T3. During the period, the common electrode voltage Vcom is applied.

  Next, the behavior of the electrophoretic particles 3 in the pixel Pij will be considered. Since the above-described reset operation is performed before this writing operation, the electrophoretic particles 3 of the pixels Pij are all located on the pixel electrode 104 side at time T1. At this time, when the gradation voltage Vij is applied to the pixel electrode 104, an electric field is applied from the pixel electrode 104 toward the common electrode 201. Therefore, the electrophoretic particles 3 start to move from time T1.

  Here, the luminance Iij in the pixel Pij in the i row and j column is determined by the average amount of movement of the electrophoretic particles in the pixel Pij. Since the electrophoretic particles 3 in this example are white and the dispersion medium 2 is black, the luminance Iij of the pixel Pij increases as the electrophoretic particles 3 approach the common electrode 201. Therefore, as shown in the figure, the luminance Iij gradually increases from time T1.

  Incidentally, since the pixel Pij is configured by sandwiching the dispersion system 1 between the pixel electrode 104 and the common electrode 201, the pixel capacitance according to the electrode area, the distance between the electrodes, and the dielectric constant of the dispersion system 1. Have

  Therefore, even if the supply of charge to the pixel electrode 104 is stopped by turning off the TFT 103, the charge is accumulated in the pixel capacitor, so that a constant electric field is continuously generated between the electrodes. Become. Since the electrophoretic particles 3 continue to migrate toward the common electrode 201 as long as an electric field is applied, a period in which the generation of the electric field is stopped, in other words, a step of removing charges accumulated in the pixel capacitor is necessary. The no-bias period Tb is provided for this purpose.

  In the no-bias period Tb, the common electrode voltage Vcom is applied to the pixel electrode 104, so that the pixel electrode 104 and the common electrode 201 are equipotential at time T2. For this reason, the electric field no longer acts on the electrophoretic particles 3 from time T2. Here, if the viscosity resistance of the dispersion medium 2 is large to some extent, the electrophoretic particles 3 stop the migration at time T2 when the external force stops working. As a result, the luminance Iij takes a constant value from the time T2 as shown in the figure. Note that when the viscous resistance of the dispersion medium 2 is small, the electrophoretic particles 3 stop after moving due to inertia even when the electric field stops working. In such a case, the image signal processing circuit 300A causes the inertia Image data D corrected in anticipation of electrophoresis is generated.

  In this writing operation, first, a charge is supplied to the pixel electrode 104 of the pixel Pij, a gradation voltage Vij is applied between the electrodes, and the electrophoretic particles 3 are moved by a distance corresponding to the gradation to be displayed. Then, the charge is supplied to the pixel electrode 104, the common electrode voltage Vcom is applied, and the migration of the electrophoretic particles 3 is stopped. Therefore, the luminance Iij of the pixel Pij is made to correspond to the gradation to be displayed. Can do. In this example, the common electrode voltage Vcom is applied in order to stop the electrophoresis of the electrophoretic particles 3. However, it is not necessary to apply a voltage that completely matches the common electrode voltage Vcom. Any voltage that can be stopped is acceptable. Since the electrophoretic particles 3 cannot migrate unless the viscous resistance is overcome, the applied voltage may be slightly different from the common electrode voltage Vcom when the viscosity resistance of the dispersion medium 2 is large.

(3) Holding Operation Next, the holding operation will be described. In FIG. 7, when the time T3 is reached, all the scanning line signals Yi become inactive, so that the TFTs 103 of all the pixels Pij are turned off. As described above, since the common electrode voltage Vcom is applied to the pixel electrode 104 in the non-bias period Tb, no electric field is generated between the electrodes.

  Therefore, unless a voltage is newly applied to the pixel electrode 104, no electric field is applied to the dispersion system 1. As a result, the spatial state of the electrophoretic particles 3 in the dispersion system 1 is maintained, whereby the content of the display image can be maintained. In such a holding period Th, since it is not necessary to apply a voltage to the pixel electrode 104, it is not necessary to generate the scanning line signals Y1 to Ym and it is not necessary to generate the data line signals X1 to Xn. . For this reason, in the said period, power consumption can be reduced with the various methods described below.

  The first method is to turn off the main power supply of the electrophoretic display device itself. As a result, the operation of the electrophoretic display panel A, the image signal processing circuit 300A as a peripheral circuit, and the timing generator 400 is stopped, and no power is consumed.

  The second method is to stop the power supply to the electrophoretic display panel A. Thereby, the power consumed by the electrophoretic display panel A can be reduced.

  A third method is to stop supplying the Y clock YCK and the inverted Y clock YCKB, and the X clock XCK and the inverted X clock XCKB to the scanning line driving circuit 130 and the data line driving circuit 140A. As described above, since the scanning line driving circuit 130 and the data line driving circuit 140A are composed of complementary TFTs, power is consumed only when a current flows, in other words, only when there is a logic level inversion. . Therefore, power consumption can be reduced by stopping the supply of the clock.

(4) Rewriting Operation Next, a rewriting operation for rewriting the contents of the display screen will be described. In the rewriting operation, there are various modes described below.

  First, in the first mode, the above-described reset operation is performed to sequentially initialize each row, and then the above-described write operation is performed to sequentially supply charges to the pixel electrodes 104 for each row, thereby A regulated voltage and a common electrode voltage Vcom are applied. As a result, the entire screen can be rewritten.

  Next, in the second mode, the reset operation and the write operation are performed only on the lines that need to be rewritten. Here, a case where the jth and j + 1th lines are rewritten will be described as an example. FIG. 11 is a timing chart for explaining the reset operation according to the second embodiment. First, in the reset period Tr, the image signal processing circuit 300A outputs reset data Drest. Further, during the period, the scanning line driving circuit 130 sequentially outputs the scanning line signals Y1,..., Yj, Yj + 1,.

  On the other hand, the non-bias timing signal Cb becomes L level only during a period in which the scanning line 101 to be rewritten is selected. In this example, since the jth and j + 1th lines are rewritten, the non-bias timing signal Cb becomes L level (inactive) during the period when the scanning line signals Yj and Yj + 1 are active. As described above, the selection circuit 144 (see FIG. 6) outputs the common voltage data Dcom when the non-bias timing signal Cb is at the H level (active), while the second latch 143 has the logic level at the L level. Output data Db1 to Dbn are output. In other words, in the period for selecting the jth and j + 1th scanning lines 101, the reset voltage Vrest is supplied to all the data lines 102, while in the selection period for the other scanning lines 101. The common electrode voltage Vcom is supplied to all the data lines 102.

  Accordingly, as shown in FIG. 11, the common electrode voltage Vcom is supplied to the pixel electrodes 104 in the first to j-1th rows and the j + 2 to mth rows, while the pixels in the jth and j + 1th rows. A reset voltage Vrest is supplied to the electrode 104. Therefore, the spatial state of the electrophoretic particle 3 is initialized in the pixels in the j-th row and the j + 1-th row. On the other hand, since the electric field is not generated even when the common electrode voltage Vcom is written to the pixel electrode 104, the spatial state of the electrophoretic particles 3 in the pixels of the first to j-1th rows and the j + 2 to mth rows. Does not change. Next, in the writing operation, the image data D is output only for the lines to be rewritten by the image signal processing circuit 300A, the common voltage data Dcom is output for the other lines, and the normal writing shown in FIG. Writing is performed in the same manner as the operation. Thereby, rewriting can be performed only in the j-th row and the j + 1-th row.

  Next, in the third aspect, a plurality of lines to be rewritten are reset at the same time, and then rewritten by a normal writing operation. In the second mode, the reset operation is sequentially performed for each row such that the j + 1th row is reset next to the jth row, but a scanning line driving circuit capable of simultaneously selecting a plurality of scanning lines 101 to be rewritten is used. It is possible to reset at the same time. For example, as shown in FIG. 12, if only the scanning line signals Yj and Yj + 1 are simultaneously activated and the reset voltage Vrest is supplied to the data line 102, the jth and j + 1th lines to be rewritten as shown in FIG. Of course, they can be reset simultaneously. In the writing operation, the image data D is output only for the lines to be rewritten by the image signal processing circuit 300A, the common voltage data Dcom is output for the other lines, and the normal writing operation shown in FIG. Write in the same way. Thereby, rewriting can be performed only in the j-th row and the j + 1-th row.

  Next, in the fourth aspect, the region to be rewritten is reset at the same time, and then a new gradation voltage is applied to the pixel electrode 104 in the region. Here, it is assumed that the region R to be rewritten is from the a-th row to the b-th row and from the c-th column to the d-th column as shown in FIG.

  First, as the scanning line driving circuit, one that can simultaneously select a plurality of scanning lines 101 to be rewritten is used as in the third mode. Next, the image signal processing circuit 300A, as data for one line, outputs common voltage data Dcom from the first to the (c-1) th, reset data Drest from the cth to the dth, and d + 1th. The common voltage data Dcom is output from the nth to the nth. The no-bias timing signal Cb is kept inactive. Thereby, in the predetermined horizontal scanning period, the data line signals X1 to Xc-1 and Xd + 1 to Xn can be set to the common electrode voltage Vcom, while the data line signals Xc to Xd can be set to the reset voltage Vrest. In the horizontal scanning period, the region R can be reset by making only the scanning line signals Ya to Yb active.

Next, in the writing operation, the image signal processing circuit 300A outputs the image data D to the pixel electrodes corresponding to the region R, and outputs the common voltage data Dcom to the other pixel electrodes. As a result, only the region R can be rewritten.
Next, in the fifth mode, all the pixels are reset at the same time, and thereafter, a normal writing operation is performed to perform rewriting. FIG. 15 is a block diagram of the electrophoresis panel B according to the fifth aspect. The electrophoretic panel B has a TFT 105 provided for each column, and the scanning line driving circuit 130B can simultaneously activate all the scanning line signals Y1 to Ym. The configuration is the same as the electrophoresis panel A shown in FIG.

  In FIG. 15, a reset voltage Vrest is supplied to the source electrode of each TFT 105, a reset timing signal Cr is supplied to its gate electrode, and its drain electrode is connected to each data line 102. Here, the reset timing signal Cr is a signal that is active only during a predetermined reset period Tr, and is generated by the timing generator 400. When the reset timing signal Cr becomes active, all the TFTs 105 are simultaneously turned on, and the reset voltage Vrest is supplied to each data line 102. On the other hand, when the reset timing signal Cr becomes active, the scanning line driving circuit 130B activates all the scanning line signals Y1 to Ym simultaneously. Accordingly, the reset voltage Vrest is applied to all the pixel electrodes 104 during the active period of the reset timing signal Cr. Thereby, all the pixels are simultaneously reset.

  In this case, each source electrode of the TFT 105 may be grounded, and a positive voltage sufficient to initialize the common electrode voltage Vcom with reference to the ground potential may be applied. That is, a voltage sufficient to initialize the other electrode may be applied with respect to the potential of either one of the pixel electrode 104 and the common electrode 201. The common electrode 201 may be divided to provide a plurality of divided electrodes (for example, an upper half and a lower half), and a voltage for initialization may be applied to the divided electrode to which the image region to be rewritten belongs. .

B: Second Embodiment In the above embodiment, when rewriting the screen, after performing the reset operation shown in FIG. 16A, the write operation shown in FIG. The display screen was updated. In this case, the spatial state of the electrophoretic particles 3 is once initialized. For example, if the dispersion medium 2 is colored black and the electrophoretic particles 3 are white, the entire screen is darkened (black) when the display is updated. Since human vision cannot detect short-term changes, if the period required for the reset operation is short, it is possible to display a moving image by updating the screen one after another.

  However, depending on the physical properties of the dispersion system 1, a long time may be required for the reset operation, and a luminance change accompanying the initialization of the electrophoretic particles 3 may be detected. Therefore, in order to eliminate such inconvenience, it corresponds to the difference between the average position of the electrophoretic particles corresponding to the gradation to be displayed next and the average position of the electrophoretic particles corresponding to the gradation currently being displayed. The voltage to be applied may be applied between the electrodes for a certain time. For example, it is assumed that the current gradation is 50% and is changed to 75% gradation. As shown in FIG. 16B, when the average position of the electrophoretic particles 3 is approximately ½ of the thickness direction of the dispersion 1, the display gradation is 50%. In order to change the gradation to 75%, it is necessary to move the average position of the electrophoretic particles 3 to about 3/4 in the thickness direction as shown in FIG. Therefore, a voltage corresponding to the difference between the gradation to be displayed next and the current gradation is supplied to the pixel electrode 104 to move the electrophoretic particles 3 to a predetermined position. Accordingly, the display screen can be updated without performing a reset operation, and a moving image can be easily displayed.

B-1: Image Signal Processing Circuit Next, the image signal processing circuit 301A will be described. FIG. 17 is a block diagram showing the configuration of the image signal processing circuit 301A. As shown in this figure, the image signal processing circuit 301A includes an A / D converter 310, a correction unit 320, a calculation unit 330, and a selection unit 340. The image signal VID supplied from the outside is supplied to the correction unit 320 as input image data Din via the A / D converter 310. The correction unit 320 includes a ROM and the like, performs correction processing such as gamma correction on the input image data Din, generates image data Dv, and outputs the image data Dv to the calculation unit 330.

  Next, the arithmetic unit 330 includes a memory 331 and a subtracter 332. The image data Dv is supplied to one input terminal of the subtracter 332 and the memory 331. The memory 331 performs a write operation in an odd field, while performing a read operation in an even field, and a second field memory 331B that performs a read operation in an odd field while performing a write operation in an even field. And. The image data Dv is delayed by one field by the memory 331 and supplied to the other input terminal of the subtractor 332 as delayed image data Dv ′.

  Next, the subtractor 332 subtracts the delayed image data Dv ′ from the image data Dv to generate difference image data Dd, and outputs this to the selection unit 340. The selection unit 340 selects the reset data Drest in the reset period Tr, while outputting the difference image data Dd in the writing period Tw. In the first field, since there is no delayed image data Dv ′, dummy data with a data value of “0” is supplied to the other input terminal of the subtractor 332. . Therefore, the image data Dv is output as the difference image data Dd in the first field.

  Here, if the delayed image data Dv ′ is the current display gradation, the image data Dv corresponds to the gradation to be displayed next. Therefore, the difference image data Dd is data corresponding to the difference between the current gradation and the gradation to be displayed next.

  Since the configuration of the drive circuit and the data line circuit of this embodiment is the same as that of the first embodiment, description thereof is omitted.

B-2: Overall Operation in Second Embodiment Next, the operation of the electrophoretic display device in the second embodiment will be described. FIG. 18 is a timing chart showing output data of the image signal processing circuit 301A. The outline of the operation will be described with reference to this figure.

  First, when the power supply of the electrophoretic display device is switched from the off state to the on state at time t0, the power is supplied to the image signal processing circuit 301A, the timing generator 400, and the electrophoretic display panel A. The image signal processing circuit 301A outputs the reset data Drest for one field period at time t1 when the predetermined period has elapsed and the circuit operation is stable. In the reset period Tr, as described in the display principle, the electrophoretic particles 3 are attracted to the pixel electrode 104 side, and the spatial state thereof is initialized. Although details will be described later, the data line driving circuit 140A outputs a reset voltage Vrest corresponding to the data value of the reset data Drest to each data line 102, while the scanning line driving circuit 130 sequentially selects each scanning line 101. As a result, the reset voltage Vrest is applied to all the pixel electrodes 104.

  Next, when the time t2 is reached, the writing period Tw starts. In the writing period Tw, the image signal processing circuit 301A outputs the difference image data Dd. Thereby, the differential gradation voltage Vd corresponding to the difference between the gradation being displayed and the gradation to be displayed next is written in each pixel electrode 104. However, in the first field (from time t2 to time t3), the image data Dv is supplied as the differential image data Dd to the data line driving circuit 140A, so that a voltage corresponding to the gradation to be displayed is applied to each pixel. It will be written in the electrode 104. However, since the display gradation is 0% (or 100%) by the reset operation, if attention is paid to the basic function, the gradation being displayed and the next display are displayed even in the first field. It can be said that the differential gradation voltage Vd corresponding to the difference from the power gradation is applied.

  In this way, when an image is displayed in the first field, a voltage corresponding to the difference gradation is applied in the next field, and a voltage corresponding to the difference gradation is applied in the subsequent fields. . For example, if the gradation voltage V corresponding to a certain pixel changes in the period from the first field F1 to the seventh field F7 as shown in FIG. 19A, such as v1, v2,. The differential gradation voltage Vd becomes Vd1, Vd2,..., Vd7 shown in FIG.

  Next, the holding period Th after time t5 is a period for holding the image written in the immediately preceding writing period Tw, and the length thereof can be arbitrarily set. In this period, the image signal processing circuit 301A stops operating and does not output data, and an electric field is not generated between the pixel electrode 104 and the common electrode 201. If there is no electric field, the electrophoretic particles 3 have no change in the spatial state. Therefore, a still image is displayed during the period.

B-2: Write Operation Next, the write operation will be described in detail. FIG. 20 is a timing chart of the electrophoretic display device in the writing operation. Here, the writing operation in the pixels of i row (i th scanning line) and j column (j th data line) will be described, but it goes without saying that the same writing is performed in other pixels. In the following description, a pixel in i row and j column is represented as Pij, a differential gradation voltage indicating a gradation to be displayed on the pixel Pij is represented as Vdij, and a luminance of the pixel Pij is represented as Iij. In this example, it is assumed that the pixel Pij displays a gradation level of 100% in the immediately preceding field. In addition, when the display gradation is changed from 0% (all the electrophoretic particles 3 are on the pixel electrode 104 side) to 100% (all the electrophoretic particles 3 are on the common electrode 201 side). The voltage required when the common electrode voltage Vcom is used as a reference is represented as + V100, and the voltage necessary for changing the display gradation from 100% to 0% is represented as -V100.

  Since the data line signals X1 to Xn are generated by D / A converting the data Dc1 to Dcn shown in FIGS. 7 (P) to (R), the data line signal Xj supplied to the jth data line 102 is generated. As shown in FIG. 20, this voltage becomes the differential gradation voltage Vdij in the differential voltage application period Tdv from time T1 to time T2. On the other hand, it becomes the common electrode voltage Vcom in the non-bias period Tb from time 2 to time T3. Here, if the gradation to be displayed in the current field is 50%, it is reduced by 50% compared with the gradation of the previous field, and therefore the value of the differential gradation voltage Vdij is shown by a solid line in FIG. As shown by -V50. Further, for example, if the gradation to be displayed in the current field is 0%, −V100 as shown by the alternate long and short dash line in FIG.

C: Third Embodiment Next, an electrophoretic display device according to a third embodiment will be described. In the electrophoretic display device of the first embodiment, a gradation voltage is applied to the pixel electrode 104, the electrophoretic particles 3 are moved by a distance corresponding to the gradation to be displayed, and then the pixel electrode 104 is moved. The common electrode voltage Vcom was applied to prevent the clonal force from acting on the electrophoretic particles 3. When the dispersion medium 2 has a small viscous resistance, the electrophoretic particles 3 migrate by inertia even after the common electrode voltage Vcom is applied. Therefore, the image data D is expected in the image signal processing circuit 300A in anticipation of inertia. Was generated.

  However, depending on the value of the viscous resistance of the dispersion medium 2, it may take a long time to stop the movement of the electrophoretic particles 3. In the above-described example, since the electrophoretic particles 3 migrate from the pixel electrode 104 toward the common electrode 201, if the viscous resistance is extremely small, the display screen gradually becomes brighter and settles to a certain brightness.

  The third embodiment provides an electrophoretic display device that can prevent such fluctuations in the brightness of the display screen, and uses an image signal processing circuit 300B in place of the image signal processing circuit 300A. Data line driving The configuration is the same as that of the electrophoretic display device of the first embodiment shown in FIG. 3 except that the data line driving circuit 140B is used instead of the circuit 140A.

C-1: Image Signal Processing Circuit First, the image signal processing circuit 300B will be described. FIG. 21 is a block diagram of the image signal processing circuit 300B, and FIG. 22 is a timing chart of the output data.

  As illustrated in FIG. 21, the image signal processing circuit 300B includes an A / D converter 310, a correction unit 320, a braking voltage data generation unit 330, and a selection unit 340. The image signal VID supplied from the outside is supplied to the correction unit 320 as input image data Din via the A / D converter 310. The correction unit 320 includes a ROM or the like, and generates image data D by performing correction processing such as gamma correction on the input image data Din.

  The braking voltage data generation unit 330 has a table that stores therein the data value of the braking voltage data Ds in association with the data value that the image data D can take, and accesses the table using the image data D as an address. Thus, the braking voltage data Ds is obtained. The table is composed of a storage circuit such as a RAM or a ROM.

  Here, the braking voltage data Ds corresponds to a braking voltage Vs described later, and is used to attenuate the movement of the electrophoretic particles 3. As described above, even if the application of the electric field to the dispersion system 1 is stopped, the electrophoretic particles 3 continue to move due to inertia, but if a force opposite to the direction of the movement is applied, the electrophoretic particles 3 The movement can be attenuated and the migration stopped. Since the electrophoretic particles 3 are initially migrated by an electric field corresponding to the gradation voltage, in order to attenuate the movement, it is necessary to first apply an electric field in the opposite direction, and secondly, the electric field strength. Is determined in accordance with the kinetic energy of the electrophoretic particles 3, in other words, the gradation voltage V. Therefore, in the present embodiment, the braking voltage data Ds corresponding to the value of the image data D is stored in advance in a table and read in consideration of the viscous resistance of the dispersion medium 2 and the like.

  Next, as shown in FIG. 22, the selection unit 340 outputs the reset data Drest during the reset period Tr, and outputs the multiplexed data Dm obtained by multiplexing the image data D and the braking voltage data Ds during the writing period. . If the image data D is 6 bits and the braking voltage data Ds is 6 bits, the multiplexed data Dm is 12-bit data, 6 bits from the MSB are image data D, and 6 bits from the LSB are braking voltage data Ds. Become.

C-2: Data Line Drive Circuit Next, the data line drive circuit 140B will be described. FIG. 23 is a block diagram of the data line driving circuit 140B. The data line driving circuit 140B according to the second embodiment is different from the first embodiment except that the first latch 142B and the second latch 143B latch 12-bit data and that the selection circuit 144B is used instead of the selection circuit 144. The configuration is similar to that of the data line driving circuit 140A.

  The first latch 142B latches the 12-bit multiplexed data Dm to generate dot sequential image data Da1 to Dan, and the second latch 143B converts the dot sequential image data Da1 to Dan into line sequential image data Db1 to Dbn. ing. However, the reset data Drest supplied during the reset period Tr is line-sequential image data Db1 to Dbn with 6 bits remaining.

  Next, FIG. 24 is a block diagram showing a detailed configuration of the selection circuit 144B, and FIG. 25 is a timing chart thereof. As shown in FIG. 24, the selection circuit 144B includes n selection units U1 to Un, and each selection unit U1 to Un has the common voltage data Dcom based on the no-bias timing signal Cb and the braking timing signal Cs. Necessary data is selected and output from the image data D and the braking voltage data Ds constituting the multiple data Dm. Here, the non-bias timing signal Cb is active (H level) only during the period for selecting the common voltage data Dcom, as in the first embodiment, while the braking timing signal Cs selects the braking voltage data Ds. It becomes active (H level) only during the period.

  The selection circuit 144B selects and outputs the image data D when both signals are inactive (L level), and further selects and outputs the braking voltage data Ds when the braking timing signal Cs is active. When Cb is active, the common voltage data Dcom is selectively output.

  For example, as shown in FIG. 25, it is assumed that multiplexed data Dmi is supplied as the i-th line sequential image data Dbi to the i-th selection unit Ui in a certain horizontal scanning period. In this case, the selection circuit 144B is supplied with the image data Di composed of the upper bits of the multiplexed data Dmi and the braking voltage data Dsi composed of the lower bits. In the gradation voltage application period Tv, the braking timing signal Cs and the no-bias timing signal Cb are both inactive, so the image data Di is selected, and in the braking voltage application period Ts, the braking timing signal Cs is Since it becomes active, the braking voltage data Dsi is selected. Further, in the no-bias period Tb, the no-bias timing signal Cb becomes active, so the common voltage data Dcom is selected.

  The data selected in this way is supplied to the D / A converter 145 shown in FIG. 23, and is output to each data line 101 as data line signals X1 to Xn.

C-3: Operation of Electrophoretic Display Device Next, the operation of the electrophoretic display device according to the third embodiment will be described. This electrophoretic display device operates in the order of reset operation → write operation → hold operation → rewrite operation (reset operation and write operation) in the electrophoretic display of the first embodiment described with reference to FIG. It is the same as the device. However, the difference is that a step of supplying a charge to the pixel electrode 104 and applying a braking voltage between the electrodes during a writing operation (including a rewriting operation) is added. Hereinafter, the details of the writing operation as a difference will be described.

  FIG. 26 is a timing chart of the electrophoretic display device in the writing operation. Here, the writing operation in the pixel Pij in the i row and the j column will be described, but it goes without saying that the same writing is performed in the other pixels.

  As shown in FIG. 26, the voltage of the data line signal Xj supplied to the jth data line 102 becomes the gradation voltage Vij in the gradation voltage application period Tv from time T1 to time T2, and from time T2 to time T3. During the braking voltage application period Ts, the braking voltage Vs is obtained, and during the no-bias period Tb from time T3 to time T4, the common electrode voltage Vcom is obtained.

  Further, the scanning line signal Yi supplied to the i-th scanning line 101 becomes active during the i-th horizontal scanning period. For this reason, the TFT 103 constituting the pixel Pij is turned on during the horizontal scanning period, and the data line signal Xj from time T1 to time T4 is taken into the pixel electrode 104 of the pixel Pij. That is, in this example, in a certain selection period of a certain scanning line, the operation from supplying the charge to the pixel electrode 104 and applying the gradation voltage Vij between the electrodes until applying the common electrode voltage Vcom is completed. .

  Next, the behavior of the electrophoretic particles 3 in the pixel Pij will be considered. Since the reset operation is performed before this writing operation, the electrophoretic particles 3 of the pixels Pij are all located on the pixel electrode 104 side at time T1. At this time, when the gradation voltage Vij is applied to the pixel electrode 104, an electric field is applied from the pixel electrode 104 toward the common electrode 201. Therefore, the electrophoretic particles 3 start to move from time T1, and the luminance Iij gradually increases.

  Then, at time T2, the braking voltage Vs is applied to the pixel electrode 104. The value of the braking voltage Vs is set according to the value of the gradation voltage Vij applied immediately before, and has a negative polarity with respect to the common electrode voltage Vcom. This is because, in the gradation voltage application period Tv, the electrophoretic particles 3 are subjected to a clonal force from the pixel electrode 104 toward the common electrode 201, and thus it is necessary to apply an electric field in a direction to cancel this. It is.

  This braking voltage Vs acts on the electrophoretic particles 3 as a brake, so that a clonal force in the direction opposite to the movement direction is applied to the electrophoretic particles 3. As a result, the electrophoretic particles 3 stop electrophoresis before the end time T3 of the stop voltage application period Ts.

  At time T3, the common electrode voltage Vcom is applied to the pixel electrode 104. Then, the voltages of the pixel electrode 104 and the common electrode 201 coincide with each other, and the charge accumulated in the pixel capacitor can be discharged. Thereby, even if the TFT 103 is turned off, no electric field is generated in the pixel Pij, so that the spatial state of the electrophoretic particles 3 can be maintained.

  As described above, in the writing operation of this embodiment, first, the electrophoretic particles 3 are moved by applying the gradation voltage Vij to the pixel electrode 104 of the pixel Pij, and further, the braking voltage Vs is applied. Thus, the movement of the electrophoretic particles 3 is attenuated and stopped, so that the electrophoretic distance due to the inertia of the electrophoretic particles 3 can be shortened even when the viscosity resistance of the dispersion medium 2 is small. As a result, it is possible to display a stable image with no change in luminance in a short time.

D: Fourth Embodiment In the above embodiment, the gradation voltage is applied, but a differential gradation voltage may be applied instead. This will be described in detail below.

D-1: Image Signal Processing Circuit First, the image signal processing circuit 301B will be described. FIG. 27 is a block diagram of the image signal processing circuit 301B.

  The braking voltage data generation unit 350 has a table that stores therein the data value of the braking voltage data Ds in association with the data value that can be taken by the difference image data Dd, and uses the difference image data Dd as an address. To obtain braking voltage data Dds. The table is composed of a storage circuit such as a RAM or a ROM.

  Here, the braking voltage data Dds corresponds to a braking voltage Vds described later, and is used to attenuate the movement of the electrophoretic particles 3. As described above, even if the application of the electric field to the dispersion system 1 is stopped, the electrophoretic particles 3 continue to move due to inertia, but if a force opposite to the direction of the movement is applied, the electrophoretic particles 3 The movement can be attenuated and the migration stopped. Since the electrophoretic particles 3 are initially migrated by the clonal force given by the electric field corresponding to the differential gradation voltage Vd, in order to attenuate the motion, it is necessary to first apply a reverse electric field. Second, the electric field strength is determined in accordance with the kinetic energy of the electrophoretic particles 3, in other words, the differential gradation voltage Vd. Therefore, in the present embodiment, the braking voltage data Dds corresponding to the value of the difference image data Dd is stored in advance in a table and read in consideration of the viscous resistance of the dispersion medium 2 and the like.

  Since the data line driving circuit and the selection circuit are the same as those in the second embodiment, description thereof is omitted.

D-2: Operation of Electrophoretic Device Next, the operation of the electrophoretic display device according to the fourth embodiment will be described.
FIG. 28 is a timing chart of the electrophoretic display device in the writing operation. Here, the writing operation in the pixel Pij in the i row and the j column will be described, but it goes without saying that the same writing is performed in the other pixels. In this example, it is assumed that the pixel Pij displays a gradation level of 100% in the immediately preceding field.
As shown in FIG. 28, the voltage of the data line signal Xj supplied to the jth data line 102 becomes the differential gradation voltage Vdij in the differential gradation voltage application period Tdv from time T1 to time T2. For example, if the gradation to be displayed in the current field is 50%, it is reduced by 50% compared to the gradation of the entire field, so the value of the differential gradation voltage Vdij is shown by a solid line in FIG. As shown by -V50. Further, for example, if the gradation to be displayed in the current field is 0%, −V100 as shown by the alternate long and short dash line in FIG. Next, in the braking voltage application period Ts from time T2 to time T3, the voltage of the data line signal Xj becomes the braking voltage Vdsij. Here, the value of the braking voltage Vdsij is determined according to the value of the differential gradation voltage Vdij. Further, in the no-bias period Tdb from time T3 to time T4, the voltage of the data line signal Xj becomes the common electrode voltage Vcom.

E: Fifth Embodiment E-1: Display Device In the electrophoretic display device according to the first embodiment, an electrophoretic particle is provided with a gradation voltage application period Tv and a non-bias period Tb within one horizontal scanning period. 3 movement and stop were completed.

  On the other hand, in the electrophoretic display device according to the fifth embodiment, a gradation voltage application period Tvf and a non-bias period Tbf are provided for each field period. The configuration of the electrophoretic display device is the same as that of the first embodiment shown in FIG. 3, and the active period of the biasless timing signal Cb is different.

E-2: Overall Operation FIG. 29 is a timing chart showing the overall operation of the electrophoretic display device. As shown in this figure, the image signal processing circuit 300A outputs reset data Drest during the reset period Tr. In this period, the electrophoretic particles 3 are attracted toward the pixel electrode 104, and the spatial state is initialized.

  Next, the writing period includes a gradation voltage application period Tvf and a non-bias period Tbf in one field unit. In the gradation voltage application period Tvf, a gradation voltage is applied to each pixel electrode 104 based on the image data D output from the image signal processing circuit 300A. However, the no-bias timing signal Cb remains inactive during the period. Therefore, the common electrode voltage Vcom is not applied to each pixel electrode 104 during the period.

  On the other hand, in the no-bias period Tbf, no data is supplied from the image signal processing circuit 300A, but since the no-bias timing signal Cb is active, the common electrode is connected to all the data lines 102 in this period. The voltage Vcom is supplied. Accordingly, the common electrode voltage Vcom is applied to each pixel electrode 104. That is, in this example, the gradation voltage V is applied to the pixel electrode 104 in a certain selection period of a certain scanning line, and the gradation voltage V is held for a period until the scanning line is next selected. The common electrode voltage Vcom is applied to the pixel electrode 104 in the next selection period of the scanning line.

  Next, in the holding period Th, an electric field is not generated between the pixel electrode 104 and the common electrode 201, and an image written in the immediately preceding writing period is held.

  In the rewriting period, a series of processes such as reset → application of gradation voltage → no bias (application of common electrode voltage) is performed as in the first image display.

E-3: Write Operation FIG. 30 is a timing chart of the electrophoretic display device in the write operation. Here, the writing operation in the pixel Pij in the i row and the j column will be described, but it goes without saying that the same writing is performed in the other pixels.

  As shown in FIG. 30, the voltage of the data line signal Xj supplied to the jth data line 102 changes every horizontal scanning period in the gradation voltage application period Tvf. In the i-th horizontal scanning period, the data line signal Xj becomes the gradation voltage Vij. At this time, since the scanning line signal Yi becomes active (H level), the gradation voltage Vij is written to the pixel electrode 104 of the pixel Pij. As a result, the voltage of the pixel electrode 104 changes from the reset voltage Vrest to the gradation voltage Vij at time T1, and an electric field corresponding to the gradation is applied to the dispersion system 1.

  At time T2, when the scanning line signal Yi becomes inactive (L level), the TFT 103 of the pixel Pij is turned off. However, since charge is accumulated in the pixel capacitor, the voltage of the pixel electrode 104 is reduced. The regulated voltage Vij is maintained.

  In the i-th horizontal scanning period of the non-bias period Tbf, when the scanning line signal Yi becomes active, the common electrode voltage Vcom is applied to the pixel electrode 104. Thereby, the voltage of the pixel electrode 104 coincides with the common electrode voltage Vcom when time T4 is reached.

E-4: Behavior of Electrophoretic Particle Next, the behavior of the electrophoretic particle 3 in the pixel Pij will be considered. Since the reset operation is performed before this writing operation, the electrophoretic particles 3 of the pixels Pij are all located on the pixel electrode 104 side at time T0. When the gradation voltage Vij is applied to the pixel electrode 104 at time T <b> 1, an electric field is applied from the pixel electrode 104 toward the common electrode 201. Therefore, the electrophoretic particles 3 start to move from time T1, and the luminance Iij gradually increases.

  The electric field corresponding to the gradation voltage Vij is applied during one field period from time T1 to time T4. Therefore, the electrophoretic particles 3 move toward the pixel electrode 104 during the period. That is, in the first embodiment, the gradation voltage Vij is applied during a predetermined period in one horizontal period, but in the third embodiment, the gradation voltage Vij is applied over one field period. The movement amount of the electrophoretic particles 3 is determined according to the strength of the electric field applied to the dispersion system 1 and the application time, as described in the display principle. In this example, since the electric field is applied for a long time of one field, a desired luminance Iij can be obtained even if a weak electric field is applied. Therefore, according to the present embodiment, the data line signals X1 to Xn can be driven with a low voltage.

F: Sixth Embodiment Further, in the above embodiment, the gradation voltage is applied, but a differential gradation voltage may be applied instead.

F-1: Display Device FIG. 31 is a timing chart showing the overall operation of the electrophoretic display device. As shown in this figure, the image signal processing circuit 301A outputs reset data Drest during the reset period Tr. In this period, the electrophoretic particles 3 are attracted toward the pixel electrode 104, and the spatial state is initialized.

  Next, the writing period Tw includes a plurality of unit periods, and one unit period is composed of a set of a differential gradation voltage application period Tdvf and a non-bias period Tdbf in one field unit. In the difference gradation voltage application period Tdvf, the difference gradation voltage Vd is applied to each pixel electrode 104 based on the difference image data Dd output from the image signal processing circuit 301A. However, the no-bias timing signal Cb remains inactive during the period. Therefore, the common electrode voltage Vcom is not applied to each pixel electrode 104 during the period.

  On the other hand, in the no-bias period Tbf, no data is supplied from the image signal processing circuit 301A. However, since the no-bias timing signal Cb is active, the common electrode is connected to all the data lines 102 in this period. The voltage Vcom is supplied. Therefore, the common electrode voltage Vcom is written to each pixel electrode 104. That is, in this example, the differential gradation voltage Vd is applied to the pixel electrode 104 in a certain selection period of a certain scanning line, and the differential gradation voltage Vd is applied during the period until the scanning line is selected next. The common electrode voltage Vcom is applied to the pixel electrode 104 in the next selection period of the scanning line.

  Next, in the holding period Th, an electric field is not generated between the pixel electrode 104 and the common electrode 201, and an image written in the immediately preceding writing period is held.

F-2: Write Operation FIG. 32 is a timing chart of the electrophoretic display device in the write operation. Here, the writing operation in the pixel Pij in the i row and the j column will be described, but it goes without saying that the same writing is performed in the other pixels. In this example, the gradation of the unit period immediately before in the pixel Pij is 10%, and 50% gradation is displayed in the current unit period.

  As shown in FIG. 32, the voltage of the data line signal Xj supplied to the jth data line 102 changes every horizontal scanning period in the differential gradation voltage application period Tdvf. In the i-th horizontal scanning period, the data line signal Xj becomes the differential gradation voltage Vdij. At this time, since the scanning line signal Yi becomes active (H level), the differential gradation voltage Vdij is applied to the pixel electrode 104 of the pixel Pij. As a result, the voltage between the two electrodes becomes the differential gradation voltage Vdij at time T1, and an electric field corresponding to the differential gradation is applied to the dispersion system 1.

  At time T2, when the scanning line signal Yi becomes inactive (L level), the TFT 103 of the pixel Pij is turned off. However, since charges are accumulated in the pixel capacitor, the voltage between the electrodes is the difference level. The regulated voltage Vdij is maintained.

  In the i-th horizontal scanning period of the non-bias period Tdbf, when the scanning line signal Yi becomes active, the common electrode voltage Vcom is applied to the pixel electrode 104. Thereby, the potential of the pixel electrode 104 coincides with the common electrode voltage Vcom when time T4 is reached.

G: Seventh Embodiment G-1: Display Device In the electrophoretic display device of the third embodiment, the gradation voltage application period Tv, the braking voltage application period Ts, and the no-bias period Tb within one horizontal scanning period. To complete the movement and stop of the electrophoretic particles 3.

  On the other hand, in the electrophoretic display device according to the seventh embodiment, a gradation voltage application period Tvf, a braking voltage application period Tsf, and a non-bias period Tbf are provided for each field. The configuration of the electrophoretic display device is the same as that of the first embodiment, but the active period of the biasless timing signal Cb is different.

G-2: Overall Operation FIG. 33 is a timing chart showing the overall operation of the electrophoretic display device. As shown in this figure, the image signal processing circuit 300A outputs reset data Drest during the reset period Tr. In this period, the electrophoretic particles 3 are attracted toward the pixel electrode 104, and the spatial state is initialized.

  Next, the writing period includes a gradation voltage application period Tvf, a braking voltage application period Tsf, and a no-bias period Tbf in one field unit. In the gradation voltage application period Tvf and the braking voltage application period Tsf, the gradation voltage V is applied to each pixel electrode 104 based on the image data D and the braking voltage data Ds output from the image signal processing circuit 300A. The braking voltage Vs is written respectively. However, the non-bias timing signal Cb remains inactive during these periods. Therefore, the common electrode voltage Vcom is not applied to each pixel electrode 104 during these periods.

  On the other hand, in the no-bias period Tbf, no data is supplied from the image signal processing circuit 300A, but since the no-bias timing signal Cb is active, the common electrode is connected to all the data lines 102 in this period. The voltage Vcom is supplied. Accordingly, the common electrode voltage Vcom is applied to each pixel electrode 104. That is, in this example, the gradation voltage V is written to the pixel electrode 104 in a certain selection period of a certain scanning line, and the gradation voltage V is held for a period until the scanning line is selected next. The braking voltage Vs is applied to the pixel electrode 104 in the next selection period of the scanning line, the braking voltage Vs is held until the scanning line is selected next, and the scanning line is selected next. The common electrode voltage Vcom is applied to the pixel electrode Vcom during the period.

  Next, in the holding period Th, an electric field is not generated between the pixel electrode 104 and the common electrode 201, and an image written in the immediately preceding writing period is held.

  In the rewriting period, as in the first image display, a series of processing such as reset → application of gradation voltage → application of braking voltage → no bias (application of a common electrode voltage) is performed.

G-3: Write Operation Next, the write operation (including the rewrite operation) of the electrophoretic display device according to the fourth embodiment will be described in detail. FIG. 34 is a timing chart of the electrophoretic display device in the writing operation. Here, the writing operation in the pixel Pij in the i row and the j column will be described, but it goes without saying that the same writing is performed in the other pixels.

  As shown in FIG. 34, the data line signal Xj becomes the gradation voltage Vij in the i-th horizontal scanning period of the gradation voltage application period Tvf. At this time, since the scanning line signal Yi becomes active (H level), the gradation voltage Vij is written to the pixel electrode 104 of the pixel Pij. As a result, the voltage of the pixel electrode 104 changes from the reset voltage Vrest to the gradation voltage Vij at time T1, and an electric field corresponding to the gradation is applied to the dispersion system 1.

  At time T2, when the scanning line signal Yi becomes inactive (L level), the TFT 103 of the pixel Pij is turned off. However, since charge is accumulated in the pixel capacitor, the voltage of the pixel electrode 104 is reduced. The regulated voltage Vij is maintained.

  Next, in the i-th horizontal scanning period of the braking voltage application period Tsf, when the scanning line signal Yi becomes active, the braking voltage Vsij corresponding to the gradation voltage Vij is applied to the pixel electrode 104. Thereby, the voltage of the pixel electrode 104 coincides with the braking voltage Vsij when the time T4 is reached.

  Further, when one field period elapses, the common electrode voltage Vcom is applied to the pixel electrode 104 when the scanning line signal Yi becomes active in the i-th horizontal scanning period of the non-bias period Tbf. As a result, the potential of the pixel electrode 104 coincides with the common electrode potential Vcom when time T4 is reached.

G-4: Behavior of Electrophoretic Particle Next, the behavior of the electrophoretic particle 3 in the pixel Pij will be considered. Since the reset operation is performed before the writing operation, the electrophoretic particles 3 of the pixels Pij are all located on the pixel electrode 104 side at time T0. When the gradation voltage Vij is applied to the pixel electrode 104 at time T <b> 1, an electric field is applied from the pixel electrode 104 toward the common electrode 201. Therefore, the electrophoretic particles 3 start to move from time T1, and the luminance Iij gradually increases.

  Next, in one field period from time T4 to time T6, the braking voltage Vsij is applied to the pixel electrode. Since the braking voltage Vsij is a negative potential with respect to the common electrode potential Vcom, a Coulomb force acts in the direction from the common electrode 201 to the pixel electrode 104. As a result, a force in the direction opposite to the direction of movement of the electrophoretic particles 3 is applied, the speed of the electrophoretic particles 3 is decreased, and the movement can be completely stopped by time T6. In addition, since the common electrode potential Vcom is applied to the pixel electrode 104 in the period from time T6 to time T7, the charge accumulated in the pixel capacitor is discharged. Thereby, even after the time T7, even if the TFT 103 of the pixel Pij is turned off, an electric field is not generated between the electrodes, and the spatial state of the electrophoretic particles 3 is maintained.

  In the second embodiment described above, the gradation voltage Vij, the braking voltage Vs, and the common electrode voltage Vcom are applied in a predetermined period of one horizontal period. In the fourth embodiment, however, one field period is applied. The gradation voltage Vij and the braking voltage Vsij are applied over the entire area. That is, in this example, since the gradation voltage Vij and the braking voltage Vsij are applied for a long time of one field, a desired luminance Iij can be obtained even with a low voltage value. Therefore, according to the present embodiment, the data line signals X1 to Xn can be driven with a low voltage.

H: Eighth Embodiment Further, in the seventh embodiment, the gradation voltage is applied, but a differential gradation voltage can be applied instead.

H-1: Display Device FIG. 35 is a timing chart showing the overall operation of the electrophoretic display device according to the eighth embodiment. As shown in this figure, the image signal processing circuit 301B outputs reset data Drest during the reset period Tr. In this period, the electrophoretic particles 3 are attracted toward the pixel electrode 104, and the spatial state is initialized.

  Next, the writing period Tw includes a plurality of unit periods, and one unit period includes a differential gradation voltage application period Tdvf, a braking voltage application period Tdsf, and a non-bias period Tdbf in one field unit. Is done. In the difference gradation voltage application period Tdvf and the braking voltage application period Tdsf, a difference gradation is applied to each pixel electrode 104 based on the difference image data Dd and the braking voltage data Dds output from the image signal processing circuit 301B. A voltage Vd and a braking voltage Vs are applied. However, the non-bias timing signal Cb remains inactive during these periods. Therefore, the common electrode voltage Vcom is not written to each pixel electrode 104 during these periods.

  On the other hand, in the no-bias period Tbf, no data is supplied from the image signal processing circuit 301B, but since the no-bias timing signal Cb is active, the common electrode is connected to all the data lines 102 in this period. The voltage Vcom is supplied. Therefore, the common electrode voltage Vcom is written to each pixel electrode 104. That is, in this example, the differential gradation voltage Vd is applied to the pixel electrode 104 in a certain selection period of a certain scanning line, and the differential gradation voltage Vd is applied during the period until the scanning line is selected next. The braking voltage Vds is applied to the pixel electrode 104 in the next selection period of the scanning line, and the braking voltage Vds is maintained until the scanning line is selected next. The common electrode voltage Vcom is applied to the pixel electrode 104 during a period selected by the pixel electrode 104.

  Next, in the holding period Th, an electric field is not generated between the pixel electrode 104 and the common electrode 201, and an image written in the immediately preceding writing period Tw is held.

H-2: Write Operation FIG. 36 is a timing chart of the electrophoretic display device in the write operation. Here, the writing operation in the pixel Pij in the i row and the j column will be described, but it goes without saying that the same writing is performed in the other pixels. In this example, the gradation of the unit period immediately before in the pixel Pij is 10%, and 50% gradation is displayed in the current unit period. As shown in FIG. 36, the data line signal Xj becomes the differential gradation voltage Vdij in the i-th horizontal scanning period of the differential gradation voltage application period Tdvf. At this time, since the scanning line signal Yi becomes active (H level), the differential gradation voltage Vdij is written to the pixel electrode 104 of the pixel Pij. As a result, the potential of the pixel electrode 104 changes to the differential gradation voltage Vdij at time T1, and an electric field corresponding to the differential gradation is applied to the dispersion system 1.

At time T2, when the scanning line signal Yi becomes inactive (L level), the TFT 103 of the pixel Pij is turned off, but since the charge is accumulated in the pixel capacitor, the voltage of the pixel electrode 104 is a difference. The gradation voltage Vdij is maintained.
Next, in the i-th horizontal scanning period of the braking voltage application period Tsf, when the scanning line signal Yi becomes active, the braking voltage Vdsij corresponding to the differential gradation voltage Vdij is applied to the pixel electrode 104. As a result, the voltage of the pixel electrode 104 coincides with the braking voltage Vdsij at time T4. Further, when one field period elapses, the scanning line signal Yi becomes active in the i-th horizontal scanning period of the non-bias period Tdbf. Then, the common electrode voltage Vcom is applied to the pixel electrode 104.

I: Application Examples Although one embodiment of the present invention has been described above, the present invention is not limited to this, and can be applied and modified without departing from the spirit thereof. For example, the modifications described below are possible. Is possible.

I-1: Display of moving images In each of the above-described embodiments, one image is formed in the order of the reset operation and the writing operation, and this is held, and the rewriting operation is performed as necessary. . Therefore, the electrophoretic display device of each embodiment is suitable for displaying a still image. However, it is a matter of course that a moving image may be displayed by shortening the reset period Tr and repeating the rewrite operation in a cycle. When displaying a moving image, first, it is desirable that the moving speed of the electrophoretic particles 3 is high. For this reason, it is preferable that the viscosity resistance of the dispersion medium 2 is small. In such a case, even if the application of an electric field to the dispersion system 1 is stopped, the electrophoretic particles 3 often migrate by inertia. Therefore, it is preferable to attenuate the movement of the electrophoretic particles 3 by applying a braking voltage as described in the second embodiment or the fourth embodiment.

I-2: Refresh Period It is preferable that the specific gravity of the dispersion medium 2 and the electrophoretic particles 3 constituting the dispersion system 1 is equal, but it is difficult to make the specific gravity of the two completely coincide with each other due to restrictions and variations in materials. In such a case, once an image is written and left for a long time, gravity may act on the electrophoretic particles 3 to cause the particles to settle and float. Therefore, it is preferable to provide the timer device shown in FIG. 37 inside the timing generator 400 and rewrite the same image at a predetermined cycle.

  The timer device 410 includes a timer unit 411 and a comparison unit 412. The timer unit 411 measures the time to generate the duration data Dt, and when either one of the write start signal Ws and the rewrite signal Ws ′ instructing normal writing becomes active, the duration data Dt. The value of is reset to “0”. The comparison unit 412 compares the continuation time data Dt with the reference time data Dref indicating a predetermined refresh period, compares the continuation time data Dt with the reference time data Dref. A rewrite signal Ws ′ is generated.

  FIG. 38 is a timing chart of the timer device 410. As shown in this figure, when the write start signal Ws becomes active, the duration data Dt of the timer unit 411 is reset and measurement is started. When a predetermined refresh period elapses, the continuation time data Dt and the reference time data Dref coincide with each other, and the rewrite signal Ws ′ becomes active. Thereafter, each time the refresh period elapses, the rewrite signal Ws ′ becomes active. On the other hand, if the write start signal Ws becomes active halfway, the measurement of the refresh period is started from that point. The display image can be refreshed by executing the rewriting operation (however, the same image) described in the above-described embodiment using the rewrite signal Ws ′ obtained in this way as a trigger.

I-3: Electronic Device Next, an electronic device using the electrophoretic display device described above will be described.
(1) Electronic book First, an example in which an electrophoretic display device is applied to an electronic book will be described. FIG. 39 is a perspective view showing the electronic book. In the figure, an electronic book 1000 includes an electrophoretic display panel 1001, a power switch 1002, a first button 1003, a second button 1004, and a CD-ROM slot 1005.

  When the user presses the power switch 1002 to insert a CD-ROM into the CD-ROM slot 1005, the contents of the CD-ROM are read and a menu is displayed on the electrophoretic display panel 1001. When the user operates the first button 1003 and the second button 1004 to select a desired book, the first page is displayed on the electrophoretic display panel 1001. The second button 1004 is pressed to advance the page, and the first button 1003 is pressed to return the page.

  In the electronic book 1000, after displaying the contents of the book, the display screen is updated only when the first button 1003 and the second button 1004 are operated. As described above, the electrophoretic particles 3 do not migrate unless an electric field is applied. In other words, no power supply is required to maintain the display image. Therefore, only when the display screen is updated, the electrophoretic display panel 1001 is driven by applying a voltage to the drive circuit. As a result, power consumption can be significantly reduced as compared with the liquid crystal display device.

  Further, since the display image of the electrophoretic display panel 1001 is displayed by the electrophoretic particles 3 that are pigment particles, the display screen does not shine. Therefore, the electronic book 1000 can display the same as a printed matter, and has an advantage of less eye fatigue even when read for a long time.

(2) Personal Computer Next, an example in which the electrophoretic display device is applied to a mobile personal computer will be described. FIG. 40 is a perspective view showing the configuration of this personal computer. In the figure, a computer 1200 includes a main body 1204 having a keyboard 1202 and an electrophoretic display panel 1206. Since the display image of the electrophoretic display panel 1206 is displayed by the electrophoretic particles 3 which are pigment particles, a backlight required for a transmissive / semi-transmissive liquid crystal display device is unnecessary. Therefore, the computer 1200 can be reduced in size and weight, and the power consumption can be greatly reduced.

(3) Mobile phone Further, an example in which the electrophoretic display device is applied to a mobile phone will be described. FIG. 41 is a perspective view showing the configuration of this mobile phone. In the figure, a mobile phone 1300 includes an electrophoretic display panel 1308 in addition to a plurality of operation buttons 1302, as well as an earpiece 1304 and a mouthpiece 1306. In the liquid crystal display device, a polarizing plate is necessary, and thus the display screen is dark. However, the electrophoretic display panel 1308 does not require a polarizing plate. Therefore, the mobile phone 1300 can display a bright and easy-to-see screen.

  In addition to the electronic devices described with reference to FIGS. 39 to 41, the electronic device includes a television monitor, an outdoor advertising board, a road sign, a viewfinder type, a monitor direct view type video tape recorder, and a car navigation device. , Pagers, electronic notebooks, calculators, word processors, workstations, videophones, POS terminals, devices equipped with touch panels, and the like. In addition, it goes without saying that the electrophoretic display panel of each embodiment and the electro-optical device including the same can be applied to these various electronic devices.

It is a disassembled perspective view which shows the mechanical structure of the electrophoretic display panel which concerns on 1st Embodiment of this invention. It is a fragmentary sectional view of the panel. It is a block diagram which shows the electrical constitution of the electrophoretic display device using the panel. It is sectional drawing which simplified and showed the structure of the division | segmentation cell of the panel. It is a graph which shows an example of the relationship between the voltage between electrodes, and a gradation density. It is a block diagram of a data line driving circuit 140A of the same device. 4 is a timing chart of a scanning line driving circuit 130 and a data line driving circuit 140A. 3 is a timing chart showing output data of an image signal processing circuit 300A. 5 is a timing chart of the electrophoretic display device in a reset operation. It is a timing chart of the electrophoretic display device in the writing operation. It is a timing chart for demonstrating the reset operation | movement which concerns on a 2nd aspect. It is a timing chart which shows operation in the case of resetting a plurality of horizontal lines simultaneously. It is a figure for demonstrating the horizontal line which should be rewritten. It is a figure for demonstrating the reset operation of an area unit. It is a block diagram which shows the electrical constitution of the electrophoresis panel B which concerns on a 5th aspect. It is sectional drawing which simplified and showed the structure of the division | segmentation cell of an electrophoretic display apparatus. It is a block diagram which shows the structure of the image signal process 301A based on 2nd Embodiment of this invention. 3 is a timing chart showing output data of the image signal processing circuit 301A. It is the figure which showed the relationship between a gradation voltage and a difference gradation voltage. It is a timing chart of the electrophoretic display device in the writing operation. It is a block diagram of image signal processing circuit 300B used for an electrophoretic display device concerning a 3rd embodiment of the present invention. It is a timing chart of the output data of the image signal processing circuit 300B. It is a block diagram of a data line driving circuit 140B used in the same device. It is a block diagram which shows the detailed structure of the selection circuit 144B used for the data line drive circuit 140B. It is a timing chart which shows operation | movement of the selection circuit 144B. It is a timing chart of the electrophoretic display device in the writing operation. It is a block diagram of the image signal processing circuit 301B which concerns on 4th Embodiment of this invention. 6 is a timing chart of the electrophoretic display device in a writing operation in the example. It is a timing chart which shows the whole operation | movement of the electrophoretic display apparatus which concerns on 5th Embodiment of this invention. It is a timing chart of the electrophoretic display device in the writing operation. It is a timing chart which shows the whole operation | movement of the electrophoresis apparatus which concerns on 6th Embodiment of this invention. 6 is a timing chart of the electrophoresis apparatus in a writing operation in the example. It is a timing chart which shows the whole operation | movement of the electrophoretic display apparatus which concerns on 7th Embodiment of this invention. It is a timing chart of the electrophoretic display device in the writing operation. It is a timing chart which shows the whole operation | movement of the electrophoresis apparatus which concerns on 8th Embodiment of this invention. 6 is a timing chart of the electrophoretic device in the writing operation of the same example. It is a block diagram of a timer device. It is a timing chart which shows operation | movement of the timer apparatus. It is a general | schematic perspective view of the electronic book which is an example of an electronic device. It is a general | schematic perspective view of the personal computer which is an example of an electronic device. It is a general | schematic perspective view of the mobile telephone which is an example of an electronic device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Dispersion system, 2 ... Dispersion medium, 3 ... Electrophoretic particle, A ... Electrophoretic display panel, 101 ... Scanning line, 102 ... Data line, 103 ... TFT (switching element), 104 ... Pixel electrode, 201 ... Common electrode , Vij ... gradation voltage, Vdij ... differential gradation voltage, Vs ... braking voltage, Y1 to Ym ... scanning line signal, X1 to Xn ... data line signal, 130 ... scanning line driving circuit (scanning line driving unit), 140A, 140B: Data line driving circuit (data line driving unit).

Claims (8)

A common electrode; a plurality of pixels; and a plurality of switching elements connected to each pixel, each of the plurality of pixels being connected to one of the switching elements and spaced apart from the common electrode. A method for driving an electrophoretic device having an opposed pixel electrode, and a dispersion system sandwiched between the common electrode and the pixel electrode and containing electrophoretic particles,
Applying a first voltage to the common electrode;
Determining a value of a second voltage for moving the electrophoretic particles to a position corresponding to a display gradation of the pixel between the pixel electrode and the common electrode at a predetermined time;
After performing a writing operation of applying the second voltage to the pixel electrode through the switching element for the predetermined time,
A method for driving an electrophoretic display device, comprising performing a biasless operation of applying the first voltage to the pixel electrode via the switching element.   In the writing operation, a voltage corresponding to the display gradation is applied to the pixel electrodes as the second voltage, and a reset voltage for moving the electrophoretic particles to an initial position prior to the writing operation. The method of driving an electrophoretic display device according to claim 1, wherein a reset operation applied to each pixel electrode is performed. A plurality of data lines, a plurality of scanning lines that three-dimensionally intersect with the plurality of data lines, a common electrode, and a plurality of data lines and the plurality of scanning lines are provided respectively corresponding to the intersections, A plurality of pixel electrodes opposed to the common electrode across a certain gap; a plurality of dispersion systems sandwiched between the plurality of pixel electrodes and the common electrode; each containing electrophoretic particles; Each on / off switching control terminal is provided corresponding to each intersection of the data line and the plurality of scanning lines, and each of the on / off switching control terminals is connected to the scanning line passing through the intersection. A driving method of an electrophoretic display device having a plurality of switching elements that connect data lines passing through the unit to pixel electrodes provided corresponding to the intersections,
An operation for display control using the plurality of scanning lines and the plurality of data lines is performed using a field having a certain length of time, and in an operation for display control in one field,
While applying a common electrode voltage to the common electrode, sequentially select the scanning lines,
Applying a voltage to turn on all the switching elements connected to the selected scanning line at once for the selected scanning line,
For each of the plurality of pixels, a gradation voltage value for moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between the pixel electrode and the common electrode is determined, and Apply a regulated voltage to the corresponding data line for a certain period of time,
Applying the common electrode voltage to the plurality of data lines;
A method for driving an electrophoretic display device, comprising: applying a voltage that collectively turns off all switching elements connected to the selected scanning line to the selected scanning line. Using each one field, the reset operation and the write operation are alternately repeated,
In the field for performing the reset operation, a reset voltage for generating an electric field that initializes a spatial state of the electrophoretic particles is applied to the plurality of data lines,
4. The method of driving an electrophoretic display device according to claim 3, wherein the gray scale voltage is applied to the plurality of data lines in the field for performing the writing operation. A plurality of data lines, a plurality of scanning lines that three-dimensionally intersect with the plurality of data lines, a common electrode, and a plurality of data lines and the plurality of scanning lines are provided respectively corresponding to the intersections, A plurality of pixel electrodes opposed to the common electrode across a certain gap; a plurality of dispersion systems sandwiched between the plurality of pixel electrodes and the common electrode; each containing electrophoretic particles; Each on / off switching control terminal is provided corresponding to each intersection of the data line and the plurality of scanning lines, and each of the on / off switching control terminals is connected to the scanning line passing through the intersection. A drive circuit for an electrophoretic display device having a plurality of switching elements that connect data lines passing through the unit to pixel electrodes provided corresponding to the intersections,
An application unit for applying a common electrode voltage to the common electrode;
The scanning lines are sequentially selected, and after applying a voltage for turning on all switching elements connected to the scanning lines at once for the selected scanning lines for a certain period, A scanning line driving unit that applies a voltage that collectively turns off all the switching elements connected to the scanning line;
For each of the plurality of pixels, a voltage value for moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between the pixel electrode and the common electrode is determined, and one scan is performed. A plurality of gradation voltages are applied to the corresponding data lines for a certain period of time within a period in which a voltage is applied to the scanning lines and the switching elements are collectively turned on. A data line driving unit for applying the common electrode voltage to the data line of
A drive circuit for an electrophoretic display device, comprising: Each of the drive circuits repeats a reset operation and a write operation alternately by using one field,
In the field for performing the reset operation, the data line driver applies a plurality of voltages for generating an electric field for initializing a spatial state of the electrophoretic particles to the plurality of data lines,
6. The field according to claim 5, wherein, in the field for performing the writing operation, the data line driving unit applies a gradation voltage corresponding to a target display gradation to the plurality of data lines. Drive circuit for electrophoretic display device. A plurality of data lines, a plurality of scanning lines that three-dimensionally intersect with the plurality of data lines, a common electrode, and a plurality of data lines and the plurality of scanning lines are provided respectively corresponding to the intersections, A plurality of pixel electrodes opposed to the common electrode across a certain gap, a plurality of dispersion systems each sandwiched between the plurality of pixel electrodes and the common electrode, each containing electrophoretic particles; Each on / off switching control terminal is provided corresponding to each intersection of the data line and the plurality of scanning lines, and each of the on / off switching control terminals is connected to the scanning line passing through the intersection. An electrophoretic display panel having a plurality of switching elements that connect data lines passing through the unit to pixel electrodes provided corresponding to the intersections;
An application unit for applying a common electrode voltage to the common electrode;
The scanning lines are sequentially selected, and after applying a voltage for turning on all switching elements connected to the scanning lines at once for the selected scanning lines for a certain period, A scanning line driving unit that applies a voltage that collectively turns off all the switching elements connected to the scanning line;
For each of the plurality of pixels, a gradation voltage value for moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between the pixel electrode and the common electrode is determined. Are applied to the corresponding data lines for a certain period of time within a period in which a voltage for turning on the switching elements at once is applied to the scanning lines. A data line driver for applying the common electrode voltage to the plurality of data lines;
An electrophoretic display device comprising: A plurality of data lines, a plurality of scanning lines that three-dimensionally intersect with the plurality of data lines, a common electrode, and a plurality of data lines and the plurality of scanning lines are provided respectively corresponding to the intersections, A plurality of pixel electrodes opposed to the common electrode across a certain gap; a plurality of dispersion systems sandwiched between the plurality of pixel electrodes and the common electrode; each containing electrophoretic particles; Each on / off switching control terminal is provided corresponding to each intersection of the data line and the plurality of scanning lines, and each of the on / off switching control terminals is connected to the scanning line passing through the intersection. An electrophoretic display panel having a plurality of switching elements that connect data lines passing through the unit to pixel electrodes provided corresponding to the intersections;
An application unit for applying a common electrode voltage to the common electrode;
The scanning lines are sequentially selected, and after applying a voltage for turning on all switching elements connected to the scanning lines at once for the selected scanning lines for a certain period, A scanning line driving unit that applies a voltage that collectively turns off all the switching elements connected to the scanning line;
For each of the plurality of pixels, a gradation voltage value for moving the electrophoretic particles to a position corresponding to the display gradation of the pixel between the pixel electrode and the common electrode is determined. Are applied to the corresponding data lines for a certain period of time within a period in which the scanning lines are selected and a voltage for collectively turning on the switching elements is applied to the scanning lines. A data line driver for applying the common electrode voltage to the plurality of data lines;
An electronic apparatus comprising an electrophoretic display device having a display portion.

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