JP2017058553A - Electrophoresis display device and driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophoresis display device capable of maintaining display quality and a driving method thereof.SOLUTION: An electrophoresis display device comprises a first substrate on which a plurality of pixel electrodes are provided, a second substrate placed to face the first substrate, an electrophoresis material layer provided between the first substrate and the second substrate, and a sealant for sealing the first substrate and the second substrate to be separated from an external atmosphere. The device further comprises an ammeter for detecting current flowing between the first substrate and the electrophoresis material layer and control means for determining distribution of a moisture content of the electrophoresis material layer from a current value detected by the ammeter and controlling drive voltage applied to the electrophoresis material layer on the basis of the moisture content.SELECTED DRAWING: Figure 2

Description

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

  Currently, a liquid crystal display (LCD) is used in various applications as a flat panel display because it is thin and can be miniaturized. In addition, as another flat panel display device suitable for achieving thinner and lower power consumption than the LCD, a display device using an electrophoretic phenomenon has been developed.

  As a typical example of a display device using an electrophoretic phenomenon, a microcapsule type electrophoretic display device has already been partially put into practical use. The microcapsule-type electrophoretic display device has negatively charged white particles and positively charged black particles dispersed in a microcapsule filled with a transparent solvent so that it can be electrophoresed by an electric field. By applying an external voltage, either positive or negative charged particles are pulled up in the display surface direction, and a desired image is formed by displaying white or black on the display surface.

  Since the size diameter of the microcapsule is as small as several tens to several hundreds of μm, when the microcapsule is dispersed in a transparent binder, it can be coated like ink. This ink is also called “electronic ink” because an image can be formed by applying a voltage from the outside as described above.

  In the microcapsule type electrophoretic display device, this electronic ink is coated on a transparent resin film on which a transparent electrode is formed, and a conductive adhesive layer formed thereon is bonded to a TFT array substrate. Thereby, for example, an active matrix display panel as shown in Patent Document 1 can be obtained.

  Usually, a member obtained by coating a transparent resin film on which a transparent electrode is formed with electronic ink is called a “front plate”, and a TFT array substrate is called a “back plate”. In the manufacture of the front plate used in the microcapsule type electrophoretic display device having the above-described configuration, the transparent ink is applied to the liquid electronic ink by various coating methods such as screen printing, spin coating, dip coating, and the like. Print on top and dry to fix. In addition, the conductive adhesive layer previously printed on a resin film or the like is bonded to the electrophoretic material layer made of electronic ink by applying heat.

  However, when the manufacturing process as described above is performed, it is manufactured due to the difference in the amount of water contained in each component of the front plate such as the transparent resin film, the electrophoretic material layer, and the conductive adhesive layer as the base material. In each front plate, the moisture content varies. As a result, in each manufactured electrophoretic display device, the electrical resistance value of the constituent member layer of the front plate changes, and it is considered that there is a difference in the response of the particles in the electronic ink to the voltage applied to the electrode on the back plate. It has been.

  When the moisture content of the front plate is large, leakage current flows between the front plate and the back plate, the voltage applied between the electrodes drops, and a sufficient potential cannot be applied to the electrophoretic material layer, resulting in ink coloring. Deteriorating defects occur. On the other hand, when the moisture content of the front plate is small, a problem called kickback occurs. Kickback is because the electrophoretic material layer and the conductive adhesive layer behave like an insulator layer in a capacitor, so that charges accumulate between the electrode and these layers, and a bias in the direction opposite to the applied voltage is applied. This is a problem that the color development of the ink decreases.

JP 2000-221546 A

  In the microcapsule type electrophoretic display device as described above, it is generally recognized that the water content of the electrophoretic material layer is greatly involved in the contrast, but the electrophoretic display device is very thin. Since it is in the form of a sheet, it is extremely difficult to examine the amount of water.

  Therefore, in the conventional manufacturing process, the electrophoretic display device is in contact with the outside air (specifically, the electrophoretic material layer is sandwiched between the front plate and the back plate, and both substrates are The outer peripheral portion is put into a constant temperature and humidity chamber in a state before being sealed with a sealing resin, etc., and the electrophoretic material layer is subjected to moisture absorption treatment under predetermined conditions (temperature, humidity, time), and then both substrates. The outer periphery of the product is sealed with a sealing resin and sent to a subsequent process, and is actually driven to measure contrast to determine whether the amount of moisture contained in the manufactured electrophoretic display device is appropriate. It was.

  As described above, conventionally, there is no choice but to determine whether or not the moisture amount is appropriate by measuring the contrast, and even if the contrast is measured and it is determined that the moisture amount is not appropriate (that is, a defective product), Since the sealing process was performed, the moisture absorption process or the drying process could not be performed, and it was treated as a defective product and could not be repaired. As a result, there is a problem that the yield of the manufacturing process is reduced.

  Further, even in an electrophoretic display device that has been determined to be non-defective, it has been extremely difficult to determine the degree of deterioration of the sealing material and to determine whether the amount of water in the environment in which it is handled is appropriate.

  An object of the present invention is to provide an electrophoretic display device capable of maintaining the quality of image display and a driving method thereof.

  The present invention includes a first substrate provided with a plurality of pixel electrodes, a second substrate disposed opposite to the first substrate, an electrophoretic material layer provided between the first substrate and the second substrate, An electrophoretic display device comprising a sealing material that seals a first substrate and a second substrate to isolate an external atmosphere, and detects an electric current flowing between the first substrate and the electrophoretic material layer An ammeter, and a control unit that obtains a distribution of the moisture content of the electrophoretic material layer from the current value detected by the ammeter and controls a drive voltage applied to the electrophoretic material layer based on the moisture content.

  Further, the control means may control the drive voltage in the divided area based on the moisture amount of the divided area for each divided area obtained by dividing the display area.

  Further, the control means may obtain the moisture content distribution using current information before and after the elapse of a predetermined time detected by at least one divided region among the plurality of divided regions.

  The control unit may include a storage unit that stores a table in which a moisture amount obtained from the current value is associated with an optimum drive waveform corresponding to the moisture amount, and the drive waveform may be determined based on the table. .

  In addition, the control unit may issue a warning signal when the moisture amount obtained from the current value detected in at least one of the plurality of divided regions exceeds the maximum moisture amount that can be voltage controlled.

  The present invention also provides a first substrate provided with a plurality of pixel electrodes, a second substrate disposed opposite to the first substrate, and an electrophoretic material layer provided between the first substrate and the second substrate. And a sealing material that seals the first substrate and the second substrate to isolate the external atmosphere, and a method for driving an electrophoretic display device, the first method at a plurality of points in a display region A water content distribution in the electrophoretic material layer is obtained from a current value flowing between the substrate and the electrophoretic material layer, and a driving voltage applied to the electrophoretic material layer is controlled for each position in the display region based on the water content distribution.

  According to the present invention, an electrophoretic display device capable of maintaining the quality of image display and a driving method thereof can be realized.

1 is a plan view of an electrophoretic display device according to an embodiment of the present invention. It is sectional drawing which follows the A-A 'line of FIG. It is a block diagram which shows the structure of the display part periphery of the electrophoretic display device which concerns on embodiment of this invention. FIG. 3 is an equivalent circuit diagram showing an electrical configuration of a pixel of the electrophoretic display device according to the embodiment of the present invention. It is a figure which shows the relationship between the electric current which flows into a pixel, and the amount of moisture, and the relationship between contrast and the amount of moisture. It is a test | inspection flowchart until determining the non-defective quality of the electrophoretic display device which concerns on embodiment of this invention. 5 is an operation flowchart until a drive waveform of the electrophoretic display device according to the embodiment of the invention is determined. It is a figure which shows an example of the division | segmentation of the display area in embodiment of this invention. It is a figure which shows an example of the timing chart of the voltage output to the scanning line in a current value acquisition operation | movement which concerns on embodiment of this invention, a data line, each control line, each power supply line, and a common electrode. It is a figure which shows an example of the electric current value acquisition operation | movement in embodiment of this invention.

  Hereinafter, an electrophoretic display device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view of an electrophoretic display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line A-A ′ of the electrophoretic display device shown in FIG. 1. In the following drawings, the scale of each member may be appropriately changed in order to make the components easy to see.

  As shown in FIG. 2, the electrophoretic display device 1 according to the present embodiment includes a TFT substrate 28 and a counter substrate 29 that are disposed to face each other, and a plurality of microcapsules that are disposed between the TFT substrate 28 and the counter substrate 29. 80. A plurality of pixel electrodes 21 are formed on the surface of the TFT substrate 28 on the adhesive layer 31 side, and a common electrode 22 is formed on the surface of the counter substrate 29 on the binder 30 side. The electrophoretic material layer 23 is formed by planarly arranging a plurality of microcapsules 80 enclosing electrophoretic particles therein. The electrophoretic display device 1 of the present embodiment is configured to visually recognize an image formed by the electrophoretic material layer 23 from the counter substrate 29 side.

  The TFT substrate 28 is a plate having a rectangular shape in a plan view made of, for example, glass or plastic and is not necessarily transparent because it is disposed on the side opposite to the viewing side. A plurality of pixel electrodes 21 for applying a voltage to the electrophoretic material layer 23 are formed in a matrix on the surface of the TFT substrate 28 on the electrophoretic material layer 23 side. On the TFT substrate 28, a driving switching element 24 and an inspection switching element 25 for supplying a voltage to the pixel electrode 21, a holding capacitor 27, a scanning line 40, a data line 50, a common potential line 90, and control lines 111 to 111 are provided. 114, a stacked structure (see FIGS. 3 and 4) in which the power supply lines 121 to 122 and the like are formed. The pixel electrode 21 is formed of a material obtained by performing nickel plating and gold plating on a Cu (copper) foil in this order, or a material such as Al (aluminum) or ITO (indium tin oxide).

  The counter substrate 29 is a plate having a rectangular shape in a plan view made of, for example, plastic, and is disposed on the viewing side. Therefore, it is necessary to use a transparent substrate. A common electrode 22 is formed on the surface of the counter substrate 29 on the side of the electrophoretic material layer 23, and a voltage is applied to the electrophoretic material layer 23 in cooperation with the pixel electrode 21 on the TFT substrate 28. The common electrode 22 is a transparent electrode formed from a material such as MgAg (magnesium silver), ITO, or IZO (indium zinc oxide).

  The electrophoretic material layer 23 is composed of a plurality of microcapsules 80 each including electrophoretic particles (white particles 82 and black particles 83). For example, the electrophoretic material layer 23 is formed into a sheet by a binder 30 made of a resin or the like and an adhesive layer 31. They are integrated and handled in a state where a protective release sheet (not shown) is attached to the surface of the adhesive layer 31. Each microcapsule 80 has a particle size of, for example, about 30 to 50 μm, and is a spherical body in which a dispersion medium 81, a plurality of white particles 82, and a plurality of black particles 83 are enclosed inside the capsule. The electrophoretic material layer 23 is sandwiched between the pixel electrode 21 and the common electrode 22, and one or a plurality of microcapsules 80 are disposed in one pixel.

  The coating 85, which is the outer shell of the microcapsule 80, is formed using a translucent polymer resin such as acrylic resin such as polymethyl methacrylate and polyethyl methacrylate, urea resin, gum arabic, and gelatin. Yes. The dispersion medium 81 is a liquid that disperses the white particles 82 and the black particles 83 in the microcapsules 80. Examples of the dispersion medium 81 include water, alcohol solvents such as methanol, ethanol, isopropanol, butanol, octanol, and methyl cellosolve, various esters such as ethyl acetate and butyl acetate, and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. , Aliphatic hydrocarbons such as pentane, hexane and octane, cycloaliphatic hydrocarbons such as cyclohexane and methylcyclohexane, benzene, toluene, xylene, hexylbenzene, hebutylbenzene, octylbenzene, nonylbenzene, decylbenzene, undecyl Aromatic hydrocarbons such as benzenes with long chain alkyl groups such as benzene, dodecylbenzene, tridecylbenzene, tetradecylbenzene, etc., halo such as methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, etc. Emissions of hydrocarbons, carboxylate or other oils may be used singly or as a mixture thereof, and the like may be added further surfactants.

  The white particles 82 are particles (polymer or colloid) made of a white pigment such as titanium dioxide, zinc white (zinc oxide), and antimony trioxide, and are used, for example, by being negatively charged. The black particles 83 are particles (polymer or colloid) made of a black pigment such as aniline black or carbon black, and are used, for example, positively charged. If necessary, these pigments include electrolytes, surfactants, etc., charge control agents, titanium-based coupling agents, aluminum-based coupling agents, dispersants such as silane-based coupling agents, lubricants, and stabilizers. Etc. can be suitably added. Further, instead of the black particles 83 and the white particles 82, for example, pigments such as red, green, and blue may be used. In this case, red, green, blue, etc. can be displayed.

  FIG. 3 is a block diagram showing a configuration around the display unit of the electrophoretic display device according to the present embodiment.

  As shown in FIG. 3, the electrophoretic display device 1 according to the present embodiment is an active matrix drive type electrophoretic display device, and includes a display unit 2, a controller 10, a storage unit 11, an ammeter 14, The scanning line driving circuit 60, the data line driving circuit 70, the common electrode driving circuit 100, the selection circuit 110, and the power supply selection circuit 120 are provided.

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

  The controller 10 controls operations of the storage unit 11, the scanning line driving circuit 60, the data line driving circuit 70, the common electrode driving circuit 100, the selection circuit 110, and the power supply selection circuit 120. For example, the controller 10 supplies timing signals such as a clock signal and a start pulse to each circuit.

  The ammeter 14 detects a current flowing through the pixel 20 under the control of the controller 10.

  The controller 10 determines the amount of water in the electrophoretic material layer 23 based on the current value obtained from the ammeter 14 and the correlation between the current flowing through the prepared pixels and the amount of water in the electrophoretic element. Based on the obtained moisture content, the drive waveform of the data line 40 is determined with reference to a table (for example, stored in the ROM or the external ROM in the controller 10) showing the relationship between the moisture content and the drive waveform. The details of the drive waveform determination method will be described later. The determined drive waveform is stored in a RAM inside the controller 10 or an external RAM.

  The controller 10 determines the moisture content based on the current value of the ammeter 14 for each predetermined divided area of the display unit 2. The “divided area” referred to here is one area obtained by dividing the entire display unit 2 into several parts, and the division method can be determined as appropriate. For example, the long side direction and the short side direction of the display unit 2 shown in FIG. 1 are each divided into two equal parts, and the water amount in each divided region is the water amount determined based on the current value detected by the ammeter 14. Can be represented. By detecting the current values of all the divided regions and determining the moisture amount of each divided region, the moisture amount distribution of the entire display unit 2 can be obtained.

  Further, the controller 10 determines whether or not the electrophoretic material layer 23 contains an appropriate amount of water based on the water content in the electrophoretic material layer 23 obtained based on the current value of the ammeter 14 (that is, the non-defective product). Whether or not) can be determined. Details of the method for determining whether or not the electrophoretic display device is acceptable will be described later.

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

  The data line driving circuit 70 supplies a data potential to the data lines X1, X2,..., Xn based on the respective driving waveforms determined in the plurality of divided regions under the control of the controller 10. The data potential is one of a reference potential GND (for example, 0 V), a high potential VSH (for example, +15 V), or a low potential VSL (for example, −15 V).

  The common electrode driving circuit 100 supplies the common potential Vcom (in this embodiment, the same potential as the reference potential GND) or the reference potential GND to the common potential line 90. During normal operation, Vcom is selected, and when it is desired to measure the current flowing through the pixel 20, the reference potential GND is selected. Note that the common potential Vcom is a potential different from the reference potential GND within a range in which no voltage is substantially generated between the common electrode 22 supplied with the common potential Vcom and the pixel electrode 21 supplied with the reference potential GND. It may be. For example, the common potential Vcom may be a value different from the reference potential GND supplied to the pixel electrode 21 in consideration of fluctuations in the potential of the pixel electrode 21 due to feedthrough.

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

  Under the control of the controller 10, the selection circuit 110 divides the display unit 2 into a plurality of divided areas, for example, and supplies a potential to an arbitrary control line when selecting any one divided area among the plurality of divided areas. To do. The control line potential takes either a high potential VH (for example, +20 V) or a low potential VL (for example, −20 V).

  The power supply selection circuit 120 divides the display unit 2 into a plurality of divided areas, for example, when selecting any one divided area among the divided areas under the control of the controller 10. Supply. The power supply line potential is either a reference potential GND (for example, 0 V) or a high potential Vd (for example, +15 V).

  Various signals are input / output to / from the controller 10, the ammeter 14, the scanning line driving circuit 60, the data line driving circuit 70, the common electrode driving circuit 100, the selection circuit 110, and the power source selection circuit 120. Description of items that are not particularly related to the form is omitted.

  FIG. 4 is an equivalent circuit diagram showing an electrical configuration of the pixel 20 of the electrophoretic display device according to this embodiment.

  In FIG. 4, the pixel 20 includes a pixel electrode 21, a common electrode 22, an electrophoretic material layer 23, a driving switching element 24, an inspection switching element 25, and a storage capacitor 27.

  The driving switching element 24 is composed of, for example, an N-type transistor. In the driving switching element 24, the scanning line 40 is electrically connected to the gate electrode, and the data line 50 is electrically connected to the drain electrode. Further, the pixel electrode 21, the storage capacitor 27, and the inspection switching element 25 are electrically connected to the source electrode. The driving switching element 24 is configured to pulse the data potential supplied from the data line driving circuit 70 (see FIG. 3) via the data line 50 via the scanning line 40 from the scanning line driving circuit 60 (see FIG. 3). Are output to the pixel electrode 21 and the storage capacitor 27 at a timing corresponding to the scanning signal supplied to the pixel.

  The inspection switching element 25 is composed of, for example, an N-type transistor, like the driving switching element 24. In the inspection switching element 25, any one of the first control line 111 to the fourth control line 114 is electrically connected to the gate electrode, and the first power supply line 121 or the second power supply line is connected to the drain electrode. Either one of 122 is electrically connected. Further, the pixel electrode 21 and the storage capacitor 27 are electrically connected to the source electrode. The inspection switching element 25 selects a power source when a constant voltage is supplied from the selection circuit 110 (see FIG. 3) to the gate electrode via any one of the first control line 111 to the fourth control line 114. A power supply potential supplied from the circuit 120 (see FIG. 3) via the first power supply line 121 or the second power supply line 122 is output to the pixel electrode 21 and the storage capacitor 27.

  A data potential is supplied to the pixel electrode 21 from the data line driving circuit 70 through the data line 50 and the driving switching element 24. In addition, a power supply potential is supplied from the power supply selection circuit 120 via either the first power supply line 121 or the second power supply line 122 and the inspection switching element 25. The pixel electrode 21 is disposed so as to face the common electrode 22 with the electrophoretic material layer 23 interposed therebetween.

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

  The electrophoretic material layer 23 is composed of a plurality of microcapsules 80 each including white particles 82 and black particles 83.

  The storage capacitor 27 is made up of a pair of electrodes arranged opposite to each other with a dielectric film therebetween, and one electrode is electrically connected to the pixel electrode 21, the driving switching element 24, and the inspection switching element 25, and the other The electrode is electrically connected to the common potential line 90. The storage capacitor 27 can maintain the data potential or the power supply potential for a certain period.

  Here, the relationship between the current flowing through the pixel and the moisture content inside the electrophoretic element and the relationship between the contrast and the moisture content inside the electrophoretic element will be described. FIG. 5A is a diagram showing the relationship between the current flowing through the pixel and the amount of moisture, and FIG. 5B is a diagram showing the relationship between contrast and the amount of moisture.

  As shown in FIG. 5 (1), it is generally considered that the current flowing through the pixel and the amount of water in the electrophoretic element are in a substantially proportional relationship. In addition, as described above, the water content of the electrophoretic material layer is greatly involved in the contrast, and as shown in FIG. 5 (2), when the water content is extremely small, the contrast is lowered and the water content is appropriate. It is generally recognized that the contrast is high (optimal contrast is obtained), and that the contrast is lowered when the amount of water is extremely increased. Since it is difficult to measure the amount of water in the electrophoretic element or in the electrophoretic material layer, the correlation between the current flowing in the pixel and the amount of water in the electrophoretic element is investigated in advance. Based on the correlation and the current value flowing through the pixel, it is possible to determine the amount of moisture inside the electrophoretic element, and to determine whether the optimal amount of moisture is included so that the contrast is good (inspection). can do. For example, in the manufacturing process, the electrophoretic element is in contact with the outside air (specifically, the electrophoretic element is sandwiched between the circuit board and the counter substrate, and the outer peripheral portions of both the substrates are sealed. In a state before sealing with a resin or the like), the current flowing through the pixel is detected, and the moisture content is determined based on the correlation between the current flowing through the pixel and the moisture content prepared in advance. By determining the contrast corresponding to the amount, it is possible to determine whether or not the amount of water contained in the electrophoretic element is optimal.

(Method for determining quality of electrophoretic display device)
Next, a quality determination method for the electrophoretic display device according to the embodiment of the invention will be described with reference to FIG.

  FIG. 6 is a flowchart showing an inspection method for determining whether the electrophoretic display device 1 according to the embodiment of the present invention is acceptable. The variables i and j used in FIG. 6 are subscripts for identifying the divided areas, and N is the number of divided areas provided in the electrophoretic display device according to the embodiment.

  First, in step S1, the controller 10 sets 1 as an initial value for i. Thereafter, the process proceeds to step S2.

In step S2, the controller 10 includes a plurality of divided areas (N = 4 in this embodiment), based on the current value detected at any one divided area P _i, the determination value D of the water content of the divided region _{Get i} . Thereafter, the process proceeds to step S3.

Here, the threshold values D _TH1 and D _TH2 of the moisture amount are set as follows.
When water content 1 <D _TH1 <water content 2 <D _TH2 <water content 3
Moisture amount 1: Moisture amount that needs to be subjected to moisture absorption treatment because the moisture amount is small due to insufficient moisture absorption treatment in the constant temperature and humidity chamber process
Moisture amount 2: Moisture amount that can operate normally without any problems
Moisture amount 3: Moisture amount that needs to be dried because of excessive moisture absorption in the constant temperature and humidity chamber process

In step S3, the controller 10 is judged value _{D i} and the threshold _{D TH1,} compares the _{D TH2,} or determination value _{D i} is the threshold _{D TH1} or less, or the determination value _{D i} is the threshold value _{D TH2} Determine if greater than. If the determination in step S3 is Yes, the process proceeds to step S7. Otherwise, the process proceeds to step S4.

  In step S4, the controller 10 increments i by 1. Thereafter, the process proceeds to step S5.

  In step S5, the controller 10 determines whether i <N. If the determination in step S5 is Yes, the process proceeds to step S2, otherwise the process proceeds to step S6.

  In step S6, the controller 10 determines that the electrophoretic display device is a non-defective product, and ends the process of FIG.

In step S7, the controller 10 compares the determination value D _j (j ≠ i) of the moisture amount based on the current value detected in the other divided region P _j with the threshold values D _TH1 and D _TH2, and determines the determination value D _j. determines There threshold _{D TH1} whether the difference is less than, or the determination value _{D j} is whether larger than the threshold _{D TH2.} If the determination in step S7 is Yes, the process proceeds to step S8, otherwise, the process proceeds to step S11. The method of determining the value of j is not particularly limited. For example, a value of j that is predetermined for each value of i may be used, or j = i + 1 or j = i−1.

In step S8, the controller 10 determines whether or not the determination value D _i is smaller than the threshold value D _TH1 . If the determination in step S8 is Yes, the process proceeds to step S9, otherwise the process proceeds to step S10.

  In step S9, the controller 10 determines that the moisture content is small due to the excessive moisture absorption process in the constant temperature and humidity chamber process, and that the moisture absorption process is necessary again in the constant temperature and humidity tank, and then the process of FIG. Exit.

  In step S10, the controller 10 determines that the amount of moisture is large due to excessive moisture absorption processing in the constant temperature and humidity chamber process, and that drying processing is necessary, and then ends the processing of FIG.

  In step S11, the controller 10 determines that there is a defect such as a short circuit in the display area, and ends the process of FIG.

  If it is determined in steps S9 and S10 that a moisture absorption process or a drying process is necessary, after the moisture absorption process or the drying process is performed on the electrophoretic display device in which the determination is made, it is determined whether the determination is good or not again according to the flow of FIG. Determine.

  If it is determined in step S11 that there is a short circuit or the like, the repair process or the like is performed, and then the quality is determined again along the flow of FIG.

  In the electrophoretic display device and the inspection method thereof according to the present embodiment, before the electrophoretic material layer 23 is sealed, the display unit 2 is divided into a plurality of regions, currents flowing in the respective regions are detected, and prepared in advance. Based on the correlation between the current and the amount of moisture, the amount of moisture for each divided region is obtained, and the necessity of moisture absorption treatment or drying treatment can be determined according to the detection result. Conventionally, in the inspection after sealing the electrophoretic material layer 23, it was determined whether the amount of water in the electrophoretic material layer 23 is appropriate. Therefore, the electrophoretic display device determined to be defective cannot be repaired, and the yield is low. Led to a decline. On the other hand, according to the electrophoretic display device and the inspection method thereof according to the present embodiment, the electrophoretic display device determined to be defective in the inspection before sealing the electrophoretic material layer 23 is repaired (moisture absorption treatment or drying). Process), the yield can be improved. Furthermore, defects such as a short circuit can be detected.

(Driving method of electrophoretic display device)
Next, a driving method (driving parameter setting method) of the electrophoretic display device according to the embodiment of the present invention will be described with reference to FIG. The variables i and j used in FIG. 7 are also subscripts for identifying the divided areas, and N is the number of divided areas provided in the electrophoretic display device according to the embodiment.

  FIG. 7 is a flowchart illustrating a driving method of the electrophoretic display device according to the embodiment of the invention.

  First, in step S101, the controller 10 sets 1 as an initial value for i. Thereafter, the process proceeds to step S102.

In step S102, the controller 10 includes a plurality of the divided areas (divided into four in this embodiment), the water content of the divided regions based on the current value detected by any one divided area P _i determination value D _i get. Thereafter, the process proceeds to step S103.

Here, the threshold _values D _TH101 , D _TH102 , D _TH103 , and D _TH104 of the moisture amount are set as follows.
When water content 101 <D _TH101 <water content 102 <D _TH102 <water content 103 <D _TH103 <water content 104 <D _TH104 <water content 105,
Moisture amount 101: Moisture amount that is too low and has a problem in display quality without control of drive voltage,
Moisture content 102: Moisture content that can be operated normally but is desirable to have drive waveform control.
Water content 103: the amount of water that can operate normally without any problems,
Moisture content 104: Moisture content that can be operated normally but is desirable to have a drive waveform control.
Moisture amount 105: Moisture amount is excessive and there is a problem in display quality without control of drive voltage

In step S103, the controller 10 is judged value _{D i} is compared with the above threshold value _{D TH101, D TH104,} determination value _{D i} is the threshold value _{D TH101} whether the difference is less than, or the determination value _{D i} is the threshold value _{D TH104} Determine if greater than. If the determination in step S103 is yes, the process proceeds to step 110, and otherwise, the process proceeds to step S104.

In step S104, the controller 10 is judged value _{D i} is compared with the above threshold value _{D TH102, D TH103,} determination value _{D i} is the threshold value _{D TH102} whether the difference is less than, or the determination value _{D i} is the threshold value _{D TH103} Determine if greater than. If the determination in step S104 is Yes, the process proceeds to step S117. Otherwise, the process proceeds to step S105.

  In step S105, the controller 10 determines that there is no abnormality. Thereafter, the process proceeds to step S106.

In step S106, the controller 10 determines the driving waveforms of the divided regions P _i by referring to the table associating the optimum drive waveform corresponding to the water content and the water content determined from the current value of the divided regions, setting the steady driving parameters of the divided regions P _i (drive waveform). Thereafter, the process proceeds to step S107.

  In Step 107, the controller 10 increments i by 1. Thereafter, the process proceeds to step S108.

  In step S108, the controller 10 determines whether i <N. If the determination in step S108 is yes, the process proceeds to step S102, otherwise, the process proceeds to step S109.

  In step S109, the controller 10 drives the electrophoretic display device 1 based on the set drive parameter for each divided region, and ends the drive parameter setting process of FIG.

In step 110, the controller 10 compares the determination value D _j (j ≠ i) of the moisture amount based on the current value detected in the other divided region P _j with the threshold values D _TH101 and D _TH104, and determines the determination value D _{j. Is} smaller than the threshold value D _TH101 or whether the determination value D _j is larger than the threshold value D _TH104 . If the determination in step S110 is Yes, the process proceeds to step S111. Otherwise, the process proceeds to step S116.

  In step S111, the controller 10 determines that a large amount of moisture has entered from the outside due to deterioration of the sealing material, or that a large amount of moisture has been discharged to the outside. Thereafter, the process proceeds to step S112.

  In step S <b> 112, the controller 10 determines whether or not the amount of moisture is sufficient to maintain display quality by controlling the drive voltage. If the determination in step S112 is No, the process proceeds to step S113. Otherwise, the process proceeds to step S114.

  In step S113, the controller 10 makes a repair recommendation to the user, and then ends the process of FIG.

In step S114, the controller 10 obtains the determination value of the water content of the divided regions based on the current value of the divided area P _i again. Thereafter, the process proceeds to step S115.

In step S115, the controller 10 refers to the table associating the optimum drive waveform corresponding to the water content and the water content determined from the current value of the divided regions, to determine the driving waveform of the divided regions P _i. Thereafter, the process proceeds to step S107.

In step S116, the controller 10 determines that a defect such as a short circuit has occurred in the region from which the determination value _Di has been acquired. Thereafter, the process proceeds to step S113.

In step S117, the controller 10 performs a comparison of the moisture content determination value _{D j} and the threshold _{D TH102, D TH103} based on the current value detected by the other divided regions _{P j,} the determination value _{D j} is the threshold _{D TH102} It is determined whether or not it is smaller or whether or not the determination value D _j is larger than the threshold value D _TH103 . If the determination in step S117 is Yes, the process moves to step S118. Otherwise, the process moves to step S119.

  In step S <b> 118, the controller 10 determines that moisture is gently entering from the outside or gently discharging to the outside. Thereafter, the process proceeds to step S114.

In step S119, the controller 10 determines whether or not a predetermined time has elapsed with the determination value D _i being out of the ranges of the threshold values D _TH102 and D _TH103 . If the determination in step S119 is Yes, the process proceeds to step S120, and otherwise, the process proceeds to step S121.

  In step S120, the controller 10 determines that moisture has partially entered from the outside or that moisture has been discharged to the outside. Thereafter, the process proceeds to step S114.

  In step S <b> 121, the controller 10 determines that the amount of moisture that has entered or discharged from the outside is extremely small. Thereafter, the process proceeds to step S106.

  Note that whether or not the amount of water is sufficient to maintain display quality by controlling the driving voltage is determined by comparison with a threshold value stored in advance.

  In addition, when the controller 10 issues a warning signal, the repair recommendation to the user may be notified to the user by, for example, a display, or may be notified by voice or the like. As a result, the user can take measures such as repairing at an early stage.

  According to the driving method of the electrophoretic display device according to the present embodiment, the moisture amount distribution in the divided area is obtained from the current value detected in each divided area, and the driving voltage applied to each divided area based on the moisture amount distribution. To control. Thereby, the drive voltage of each divided area in the display unit 2 can be appropriately controlled according to the state and degree of moisture at that time, and the display quality of the entire display unit 2 can be sufficiently maintained. Furthermore, defects such as a short circuit can be detected.

  A fine moisture distribution can also be detected by obtaining the amount of water in the divided region by using current information during a predetermined time in the divided region.

  In addition, the drive waveform of each divided region is determined based on a table stored in the storage unit 11 in which the moisture amount determined from the current value flowing in the electrophoretic material layer 23 is associated with the optimum drive waveform for the moisture amount. Therefore, the drive waveform can be determined without performing complicated calculations, and the configuration of the drive voltage control means can be simplified.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the number when the display unit 2 is divided is not limited to the above-described embodiment, and can be changed as appropriate, and other parts of the electrophoretic display device can be changed as appropriate.

(Current value acquisition operation and display operation in electrophoretic display device)
Next, a current value acquisition operation and a display operation of the electrophoretic display device 1 according to the embodiment of the present invention will be described. The current value acquisition operation and the display operation are executed at a predetermined timing such as when the power is turned on or a preset number of times of writing, for example, and the current value acquisition operation acquires a current value flowing for each divided region, It is an operation to determine the moisture amount for each divided region using the acquired current value, and to determine the drive waveform for each divided region based on the table in which the moisture amount and the optimum drive waveform for the moisture amount are associated with each other. The operation is an operation for displaying an image using the determined drive waveform.

  First, the current value acquisition operation according to the present embodiment will be described with reference to FIGS. This current value acquisition operation is an operation for obtaining a moisture content distribution used to ensure display quality of the electrophoretic display device.

  As shown in FIG. 8, the display panel 2 is divided into, for example, four regions P1 to P4 in advance. That is, the scanning lines Y1 to Ym are divided into two groups of Y1 to Y (m / 2) and Y (m / 2 + 1) to Ym for each of a plurality of predetermined lines, and the data lines X1 to Xn are X1 to X (n / 2) and X (n / 2 + 1) to Xn are divided into two groups.

  The controller 10 controls the scanning line driving circuit 60, the data line driving circuit 70, the common electrode driving circuit 100, the selection circuit 110, and the power supply selection circuit 120 as a part of initialization processing at the time of power-on, for example. A signal is supplied to instruct the start of the current value acquisition operation.

  According to this control, the scanning line driving circuit 60 outputs a low level voltage VL (non-selection level) to all the scanning lines Y1 to Ym as shown in FIGS. 9 (1) to 9 (4).

  As shown in FIGS. 9 (5) to 9 (8), the data line driving circuit 70 outputs the reference potential GND to all the data lines X1 to Xn.

  As shown in FIG. 9 (15), the common electrode driving circuit 100 switches the switch 101 to connect the reference potential GND to one end of the ammeter 14.

  As shown in FIGS. 9 (9) to 9 (12), the selection circuit 110 includes a first control line 111 and a third control line 113 corresponding to the group of data lines X1 to X (n / 2). , The second control line 112 and the fourth control line 114 corresponding to the groups of the data lines X (n / 2 + 1) to Xn are alternately supplied with the high level voltage VH (selection level) only during the measurement period ts. In other periods, the low level voltage VL (non-selection level) is sequentially output. Here, the measurement period ts is set to the time required to measure the total detection current Idata, which is the sum of the currents flowing through the plurality of pixels 20 included in one divided region, by the ammeter 14.

  As shown in FIGS. 9 (13) to 9 (14), the power supply selection circuit 120 includes the first power supply line 121 corresponding to the group of the scanning lines Y1 to Y (m / 2) and the scanning line Y (m / 2 + 1) to the second power supply line 122 corresponding to the group Ym are alternately set voltage Vd (for example, +15 V) only during the voltage application period td and other periods (excluding the voltage application period td). During the period, the reference potential GND is sequentially output. Here, the voltage application period td is the total sum of currents flowing through the plurality of pixels 20 included in each divided region in each of, for example, two divided regions arranged in the column direction (that is, the Y direction) of the display panel 2. The voltage application period td is set longer than the time required to measure the current Idata with the ammeter 14, for example, the voltage application period td is set to the measurement period ts × the number of divisions in the column direction + the additional period tq × 2.

  As a result, for example, as shown in FIG. 10, the controller 10 outputs the high level voltage VH to the first control line 111 of the selection circuit 110, and the set voltage Vd (+15 V) to the first power supply line 121 of the power supply selection circuit 120. ) Are simultaneously output, the inspection switching elements 25 of the m / 2 × n / 2 pixels 20 in the first to m / 2th rows and the first to n / 2th columns in the region P1 are provided. Since the reference potential GND is connected to the common power supply driving circuit 100, the current Id flows through the series circuit of the inspection switching element 25 and the electrophoretic material layer 23 of each of these pixels. On the other hand, no current flows through the other pixels.

  As a result, the current flowing through the ammeter 14 is inspected for each of the m / 2 × n / 2 pixels 20 in the first row to the m / 2th row and the first column to the n / 2th column in the region P1. The total detection current Idata is the total of the currents flowing through the switching element 25 and the electrophoretic material layer 23.

  The current value of the total detected current Idata measured by the ammeter 14 is digitally converted by, for example, an AD converter mounted on the controller 10.

  The controller 10 acquires 1 / (m / 2 × n / 2) of the current value of the total detection current Idata as a detection current Id for one pixel 20, and a current prepared in advance from the acquired detection current Id. A moisture content distribution is obtained based on the correlation with the moisture content. As described above, generally, as shown in FIG. 5 (1), the current flowing through the pixel and the amount of water in the electrophoretic material layer 23 are approximately proportional to each other, whereas, as shown in FIG. 5 (2). As described above, it is known that when the amount of water is extremely small, the contrast is low, when the amount of water is appropriate, the contrast is high (optimal contrast is obtained), and when the amount of water is extremely large, the contrast is low. . Since it is difficult to measure the amount of moisture, by investigating the correlation between the current flowing through the pixel and contrast in advance, the optimal contrast can be obtained when how much current flows from the correlation to the pixel. It can be determined (inspected) whether a proper amount of water is contained.

  Further, the drive waveform of the data line 40 is determined with reference to a table (for example, stored in the ROM inside the controller 10 or the external ROM) showing the relationship between the moisture content and the optimum drive waveform based on the obtained moisture content. Then, the determined drive waveform is stored in the RAM inside the controller 10 or the external RAM.

  The electrophoretic display device 1 according to the present embodiment sequentially executes the current value acquisition operation for one divided region for all the divided regions of the display panel 2, and determines the water content of the electrophoretic material layer 23 for each divided region. The drive waveform corresponding to each divided area is acquired and stored in the RAM inside the controller 10 or in the external RAM.

  During the display operation, the drive voltage applied to the data line 50 from the data line drive circuit 70 is controlled using the drive waveform corresponding to each divided region stored in the RAM inside the controller 10 or the external RAM. Thereby, the drive voltage of each area | region in the display part 2 can be controlled appropriately according to the state and the level of the water | moisture content at that time, and the display quality of the display part 2 whole can fully be maintained.

  The various voltages shown in the embodiment are examples, and a write operation to a selected pixel can be appropriately performed during a display operation, and a current flowing through the electrophoretic material layer 23 is measured during a current value acquisition operation. If possible, the voltage relationship is arbitrary.

  The present invention can be used in an electrophoretic display device capable of maintaining the quality of image display.

DESCRIPTION OF SYMBOLS 1 Electrophoretic display device 2 Display part 10 Controller 11 Memory | storage part 12 Driver IC
13 counter electrode contact portion 14 ammeter 20 pixel 21 pixel electrode 22 common electrode 23 electrophoretic material layer 24 switching element for driving 25 switching element for inspection 27 holding capacitor 28 TFT substrate (back plate)
29 Counter substrate (front plate)
30 Binder 31 Adhesive Layer 32 Sealant 40 Scan Line 50 Data Line 60 Scan Line Drive Circuit 70 Data Line Drive Circuit 80 Microcapsule 81 Dispersion Medium 82 White Electrophoretic Particle 83 Black Electrophoretic Particle 85 Coating 90 Common Potential Line 100 Common Electrode Drive circuit 101 Switch 110 Selection circuit 111 1st control line 112 2nd control line 113 3rd control line 114 4th control line 120 Power supply selection circuit 121 1st power supply line 122 2nd power supply line

Claims (6)

A first substrate provided with a plurality of pixel electrodes;
A second substrate disposed opposite the first substrate;
An electrophoretic material layer provided between the first substrate and the second substrate;
A sealing material for sealing a space sandwiched between the first substrate and the second substrate and isolating it from an external atmosphere;
An ammeter for detecting a current flowing in the electrophoretic material layer;
Control means for obtaining a distribution of water content of the electrophoretic material layer from the current value detected by the ammeter and controlling a drive voltage applied to the electrophoretic material layer based on the water content. An electrophoretic display device.   2. The electrophoretic display according to claim 1, wherein the control unit controls, for each divided area obtained by dividing the display area, a driving voltage in the divided area based on the moisture amount in the divided area. apparatus.   The said control means calculates | requires the distribution of the said moisture content using the electric current information before and behind the predetermined time passage which the at least 1 said division area detected among several division areas. 2. The electrophoretic display device according to claim 1.   The control unit includes a storage unit that stores a table in which the moisture amount obtained from the current value is associated with an optimum driving waveform corresponding to the moisture amount, and a driving waveform of the driving voltage based on the table The electrophoretic display device according to claim 1, wherein the electrophoretic display device is determined.   The control means issues a warning signal when the moisture amount obtained from the current value detected in at least one of the plurality of divided regions exceeds a maximum moisture amount that can be voltage controlled. The electrophoretic display device according to claim 1, wherein the electrophoretic display device is characterized in that: A first substrate provided with a plurality of pixel electrodes; a second substrate disposed opposite to the first substrate; an electrophoretic material layer provided between the first substrate and the second substrate; A method for driving an electrophoretic display device comprising: a sealing material that seals the first substrate and the second substrate to isolate an external atmosphere;
Obtain the moisture content distribution in the electrophoretic material layer from the current value flowing in the electrophoretic material layer,
A driving method for an electrophoretic display device, wherein a driving voltage applied to the electrophoretic material layer is controlled for each position in the display region based on the moisture distribution.