JP4356283B2 - Driving method of display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for driving a display element that performs display by deposition / dissolution of a metal, and relates to a method for driving a display element suitable for so-called electronic paper.
[0002]
[Prior art]
In recent years, with the spread of networks, documents that have been distributed in the form of printed materials have been distributed in the form of so-called electronic documents. Furthermore, books and magazines are often provided in the form of so-called electronic publishing. In order to view such information, reading from a CRT (cathode ray tube) or liquid crystal display of a computer has been widely performed.
[0003]
However, it has been pointed out that a light-emitting display such as the CRT is extremely fatigued for ergonomic reasons and cannot withstand long-time reading. Even light-receiving displays such as liquid crystal displays are not suitable for reading because of the flicker inherent in fluorescent tubes. In addition, there is a problem that the reading place is limited to the place where the computer is installed.
[0004]
In recent years, a reflective liquid crystal display that does not use a backlight has been put into practical use. However, the reflectance when no liquid crystal is displayed (white display) is 30 to 40%, which is the reflectance of printed matter on paper (OA paper). And the reflectance of 75% for paperback books and 52% for newspapers). In addition, fatigue is likely to occur due to glare caused by the reflector, and this is also not able to withstand long-time reading.
[0005]
In order to solve these problems, what is called a paper-like display or electronic paper is being developed. These are colored by moving colored particles between electrodes mainly by electrophoresis or rotating particles having dichroism in an electric field. However, in these methods, the gaps between the particles absorb light, resulting in poor contrast, and a practical writing speed (within 1 second) cannot be obtained unless the driving voltage is set to 100 V or higher. There is a difficulty.
[0006]
In contrast to these display systems, electrochemical display elements (electrochromic display: ECD) that produce color based on electrochemical action are superior to the above-mentioned displays in terms of high contrast. For example, it has already been put into practical use as a light control glass or a display for a watch. However, since the light control glass and the display for a clock do not need to be driven in the first place, they are not suitable for display applications such as electronic paper. In general, the black quality is inferior, and the reflectance is low.
[0007]
In addition, in displays such as electronic paper, it will continue to be exposed to sunlight and room light for its use, but in electrochemical display elements such as those practically used in the above light control glass and watch display. Since an organic material is used to form a black portion, a problem arises in terms of light resistance. In general, an organic material has poor light resistance, and when used for a long time, it fades and the black density decreases.
[0008]
In order to solve such a technical problem, an electrochemical display element using metal ions as a material that changes color has been proposed. In this electrochemical display element, metal ions are mixed in the polymer electrolyte layer, the metal is deposited and dissolved by electrochemical oxidation / reduction, and display is performed using the color change associated therewith. Here, for example, if a colorant is contained in the polymer electrolyte layer, the contrast when a color change occurs can be increased.
[0009]
[Problems to be solved by the invention]
By the way, in the electrochemical display element which displays by said metal precipitation and melt | dissolution, it displays using the threshold voltage which is a deposition overvoltage. In each pixel, when a negative voltage exceeding a threshold voltage is applied between electrodes arranged in a matrix, metal is deposited, and when a positive voltage is applied, the metal is dissolved.
[0010]
However, in the method in which the metal is selectively deposited using the threshold voltage, a certain amount of time is required for the deposition of the metal, so that there remains a problem in terms of response speed. For example, in order to display the entire panel, a time obtained by multiplying the deposition response time by the number of electrodes is required, and as the number of electrodes increases, the display takes time. From the experiment, it is known that the deposition response time is about 0.3 seconds. For example, when the number of electrodes is 100, the time required to display one screen is about 30 seconds.
[0011]
Further, in the above-described electrodeposition type display element, each pixel has a characteristic that the characteristic as a capacitor is mainly strong before the metal is deposited, and the resistance value is reduced with the deposition. Therefore, if there is sufficient metal deposition in the pixel, a large amount of current flows between the electrodes and the potential drop increases, and as a result, unnecessary current flows through the pixel that has become low resistance due to metal deposition, causing crosstalk. May occur or the contrast may decrease.
[0012]
Further, in the electrodeposition type display element, the display contrast tends to decrease with the passage of time, and countermeasures are desired.
[0013]
The present invention has been proposed in view of such conventional situations. That is, an object of the present invention is to provide a driving method capable of shortening the time required for display in an electrodeposition type display element. It is another object of the present invention to provide a driving method capable of accurate precipitation display without crosstalk. It is another object of the present invention to provide a driving method capable of maintaining an image for a long time in an electrodeposition type display element.
[0014]
[Means for Solving the Problems]
In order to achieve the above-described object, the display element driving method of the present invention applies a voltage to each pixel by electrodes arranged in a matrix, and deposits and dissolves the metal to display an image. a step of precipitating crystals as a core in a predetermined pixel by adding the threshold voltage or higher is selectively deposited overvoltage out overvoltage to a predetermined pixel letting, in addition to a voltage lower than the threshold voltage simultaneously to all the pixels, nuclear And depositing metal on the predetermined pixel on which is deposited, writing to the pixel, and after writing to the pixel, applying a voltage lower than the threshold voltage to maintain the writing state Is included . Thereby, shortening of display time, maintenance of a display state, etc. are realized.
[0016]
As described above, when it is attempted to complete the metal deposition at the time of address driving, it takes a long time for each pixel to be deposited. In particular, as the number of scanning lines (the number of electrodes) increases, the display takes longer. On the other hand, if only crystals serving as nuclei are precipitated, the time required is much shorter than when writing is completed, and the time required for addressing is greatly reduced. The voltage for depositing additional metal can be applied to all the scanning lines simultaneously, and the time required for this can be shortened. Thus, in the present invention, the total time required for display is shortened by the combination of high-speed address and batch deposition.
[0017]
In addition, when the above method is used, addressing of the entire panel is performed in a state where metal deposition is insufficient and the resistance value of the pixel is high, so that a potential drop due to electrode resistance is reduced, and an accurate address voltage is applied to the pixel. Will be. As a result, accurate precipitation display without crosstalk is realized.
[0019]
A display element that performs display by deposition and dissolution of metal has a certain level of display memory, and can maintain display for several tens of minutes to several hours. However, the display contrast tends to decrease with time. As described above, when a voltage lower than the threshold voltage, which is the deposition overvoltage, is applied at an arbitrary timing after writing to the pixel (metal deposition), re-deposition is performed only in the pixel once the metal is deposited, The display state is maintained.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a display element driving method to which the present invention is applied will be described in detail with reference to the drawings.
[0021]
Prior to the description of the driving method, first, a configuration example of a display element (display device) targeted by the present invention will be described.
[0022]
The display device of this example is an electrochemical display device in which display is performed by deposition and dissolution of metal using the electrodeposition characteristics, and is driven by a simple matrix driving method. Therefore, the drive electrode is composed of the first electrode group X ₁ , X ₂ ... And the second electrode group Y ₁ , Y ₂ ... Orthogonal to the _first electrode group X ₁ , X _2. Are arranged in a shape. FIG. 1 and FIG. 2 show the specific structure, and a striped transparent column electrode 2 corresponding to the first electrode group is formed on the transparent substrate 1. Further, a base substrate 3 on which a stripe-like counter electrode (row electrode) 4 corresponding to the second electrode group is formed is disposed so as to face this, and these are superposed via a polymer electrolyte layer 5. A predetermined number of the transparent column electrodes 2 and row electrodes 4 are formed according to the number of pixels, and the intersection of these is a pixel.
[0023]
In the above configuration, the transparent substrate 1 can be a transparent glass substrate such as a quartz glass plate or a white plate glass plate, but is not limited thereto, an ester such as polyethylene naphthalate or polyethylene terephthalate, polyamide, Polycarbonate such as polycarbonate, cellulose ester such as cellulose acetate, fluoropolymer such as polyvinylidene fluoride and tetrafluoroethylene-hexafluoropropylene copolymer, polyether such as polyoxymethylene, polyacetal, polystyrene, polyethylene, polypropylene, methylpentene polymer And polyimides such as polyimide-amide and polyetherimide can be mentioned as examples. When these synthetic resins are used as a support, a rigid substrate that does not easily bend can be used, but a flexible film-like substrate can also be used.
[0024]
For the transparent column electrode 2, for example, a mixture of In ₂ O ₃ and SnO ₂ , a so-called ITO film, or a film coated with SnO ₂ or In ₂ O ₃ is preferably used. These ITO films or films coated with SnO ₂ or In ₂ O ₃ may be doped with Sn or Sb, and MgO, ZnO or the like can also be used.
[0025]
On the other hand, the matrix (matrix) polymer used for the polymer electrolyte layer 5 has skeleton units of-(C-C-O) _n -,-(C-C-N) _n- , and-(C- And polyethylene oxide, polyethyleneimine, and polyethylene sulfide represented by C—S) _n —. These may be branched as a main chain structure. Polymethyl methacrylate, polyvinylidene fluoride, polyvinylidene chloride, polycarbonate and the like are also preferable.
[0026]
When forming the polymer electrolyte layer 5, it is preferable to add a required plasticizer to the matrix polymer. As the preferred plasticizer, when the matrix polymer is hydrophilic, water, ethyl alcohol, isopropyl alcohol and a mixture thereof are preferable. When the matrix polymer is hydrophobic, propylene carbonate, dimethyl carbonate, ethylene carbonate, γ-butyrolactone is preferable. Acetonitrile, sulfolane, dimethoxyethane, ethyl alcohol, isopropyl alcohol, dimethylformamide, dimethylsulfoxide, dimethylacetamide, n-methylpyrrolidone, and mixtures thereof are preferred.
[0027]
The polymer electrolyte layer 5 is formed by dissolving an electrolyte in the matrix polymer. As the electrolyte, in addition to a metal salt that functions as a coloring material for display, a quaternary ammonium halide (F, Cl, Br, I), alkali metal halides (LiCl, LiBr, LiI, NaCl, NaBr, NaI, etc.), alkali metal cyanide, alkali metal thiocyanate, etc., and at least one kind selected from these A solution containing a supporting electrolyte is dissolved as an electrolyte. Here, examples of the metal ions constituting the metal salt that functions as a coloring material for display include bismuth, copper, silver, lithium, iron, chromium, nickel, cadmium, etc., and these can be used alone or in combination. Use. As the metal salt, any salt of these metals may be used. Examples of silver salts include silver nitrate, silver borofluoride, silver halide, silver perchlorate, silver cyanide, and silver thiocyanide. Can do.
[0028]
The polymer electrolyte layer 5 may be added with a coloring material in order to improve contrast. When the color due to metal deposition is black, the background color is preferably white, and a white material with high concealment is preferably introduced as the colorant. As such a material, coloring white particles can be used, and as the coloring white particles, titanium dioxide, calcium carbonate, silica, magnesium oxide, aluminum oxide and the like can be used.
[0029]
In this case, the mixing ratio of the white pigment is preferably about 1 to 20% by weight, more preferably about 1 to 10% by weight, and further preferably about 5 to 10% by weight in the case of using inorganic particles. This ratio is restricted because white pigments such as titanium oxide are not soluble in the polymer but only disperse, and as the mixing ratio increases, the white pigment aggregates, resulting in an optical density. This is because it becomes uneven. Moreover, since the white pigment has no ionic conductivity, an increase in the mixing ratio causes a decrease in the conductivity of the polymer electrolyte. Considering both, the upper limit of the mixing ratio is about 20% by weight.
[0030]
When inorganic particles are mixed in the polymer electrolyte layer 5 as a colorant as described above, the thickness of the polymer electrolyte layer 5 is preferably 10 to 200 μm, more preferably 10 to 100 μm, and still more preferably 10 to 10 μm. 50 μm. The thinner the polymer electrolyte layer 5 is, the smaller the resistance between the electrodes, so that the time required for color development and decoloration is shortened and the power consumption is reduced. However, when the thickness of the polymer electrolyte layer 5 is less than 10 μm, the mechanical strength is lowered, and problems such as pinholes and cracks occur. Moreover, when the thickness of the polymer electrolyte layer 5 is too thin, the amount of the inorganic particles mixed in may be reduced as a result, and whiteness (optical density) may not be sufficient.
[0031]
In addition, when using a pigment | dye as a coloring material mixed in the polymer electrolyte layer 5, as a ratio which mixes a coloring material, 10 weight% or less may be sufficient. This is because the coloring efficiency of the dye is much higher than that of the inorganic particles. Therefore, sufficient contrast can be obtained even with a small amount as long as the dye is electrochemically stable. As such a pigment, for example, an oil-soluble dye is preferable.
[0032]
The base substrate 3 provided on the back side is not necessarily transparent, and a substrate, a film, or the like that can reliably hold the row electrode 4 can be used. For example, it is possible to use a glass substrate such as a quartz glass plate and a white glass plate, a ceramic substrate, a paper substrate, and a wood substrate. Of course, the present invention is not limited to this, and a synthetic resin substrate or the like can also be used. Synthetic resin substrates include esters such as polyethylene naphthalate and polyethylene terephthalate, cellulose esters such as polyamide, polycarbonate, and cellulose acetate, fluoropolymers such as polyvinylidene fluoride and polytetrafluoroethylene-cohexafluoropropylene, and polyoxymethylene. Examples include polyether, polyacetal, polystyrene, polyethylene, polypropylene, polyolefins such as methylpentene polymer, and polyimides such as polyimide-amide and polyetherimide. When these synthetic resins are used as the base substrate, a rigid substrate that does not bend easily can be used, but a flexible film-like substrate can also be used.
[0033]
For the row electrode 4, a conductive material such as a metal material can be used. However, if the potential difference between the metal constituting the row electrode 4 and the metal deposited on the transparent column electrode 2 is large, charges are accumulated on the electrode in the colored state, and the movement of the charge occurs to color unintended pixels. There is a risk of it. In particular, when the potential difference exceeds the deposition overvoltage (threshold for simple matrix driving) when the metal is deposited, there is a possibility that the coloring occurs. Therefore, it is desirable to select a metal for the row electrode 4 such that the potential difference with the metal deposited as the coloring material is less than the deposition overvoltage (threshold). Ideally, the metal material of the row electrode 4 is in a state (metal state) before ionization of metal ions used in the color forming material. That is, for example, when silver precipitation / dissolution is used, silver is used for the row electrode 4, and the same metal as the metal deposited / dissolved is used for the row electrode 4. As a result, the potential difference does not occur when metal is deposited on the transparent column electrode 2.
[0034]
The above is the configuration of the display device using the electrodeposition characteristics. Next, a method for driving the display device will be described.
[0035]
In a display device using the electrodeposition characteristic, for example, when a triangular wave voltage as shown in FIG. 3 is applied between the column electrode and the row electrode, a current-voltage transient response characteristic as shown in FIG. 4 is shown. FIG. 4 is an example of characteristics when the row electrode is an Ag electrode and silver ions and iodine ions are dissolved in the polymer electrolyte.
[0036]
Referring to FIG. 4, when a voltage is applied from zero to a minus side between the column electrode and the row electrode, silver does not precipitate for a while, and silver deposits on the column electrode when the threshold voltage _Vth is exceeded. Begins. In FIG. 4, the current accompanying the deposition begins to flow when the threshold voltage _Vth is _exceeded, which is understood. As described above, each pixel has a characteristic that is mainly strong as a capacitor before deposition (white) and decreases in resistance value as it is deposited (black). This is represented by an equivalent circuit shown in FIG. be able to.
[0037]
Silver deposition, beyond the write voltage V _w which corresponds to the apex of the triangular wave voltage, gradually followed by even lower voltage, followed by even lower than the previous threshold voltage V _th. The silver deposition ends when the applied voltage _drops to the holding voltage V _ke . This suggests important findings. That is, if once nuclei (seeds) exceeds the threshold voltage V _th is formed, even in the threshold voltage V _th or less of the voltage is that silver precipitation occurs. As will be described later, the present invention makes full use of this phenomenon.
[0038]
On the other hand, when a reverse polarity (plus) voltage is applied between the column electrode and the row electrode, the dissolution of silver begins, and the silver that has been deposited when it reaches the erase voltage V _ith disappears. When a higher voltage than this is applied, iodine is liberated and adheres to the electrode, resulting in yellow coloration.
[0039]
Considering driving of a display device exhibiting current-voltage transient response characteristics as described above, most simply, a voltage exceeding the threshold voltage is applied during address driving to deposit silver, and pixel writing is performed. It is possible. Hereinafter, for simplification of description, the drive voltage waveform in this case will be described using a monochrome display by 3 × 3 pixels shown in FIG. 6 as an example.
[0040]
FIG. 7 shows an electrodeposition display element in which silver is deposited on the column electrode when a negative voltage is applied and becomes larger than the threshold voltage _Vth, and silver is dissolved when a positive voltage is applied. An example of the drive voltage waveform which displays is shown. In FIG. 7, the column voltage applied to each column electrode C ₁ , C ₂ , C ₃ , the row voltage applied to each row electrode R ₁ , R ₂ , R ₃ , and the pixels (C ₁ , R ₁ ), ( The applied voltages of C ₁ , R ₂ ) and (C ₂ , R ₂ ) are shown.
[0041]
In display, each column electrode _{C 1,} C 2, the threshold voltage _{V th} is less than the signal writing voltage pulse _{V sig} addition to _{C 3,} the threshold voltage _{V th} to each row electrodes _{R 1,} R 2, _{R 3} A small selection voltage pulse V _sel is applied, and selection operations are performed in order from the top. At this time, a voltage (write voltage V _w ) (= V _sig −V _sel ) greater than the threshold voltage V _{th is} applied only to the pixel on which silver is deposited, and silver is deposited on the transparent column electrode to perform writing.
[0042]
For example, in the pixels (C ₁ , R ₁ ) and (C ₂ , R ₂ ), the signal write voltage pulse V _sig for the column electrodes C ₁ and C ₂ and the select voltage pulse V _sel for the row electrodes R ₁ and R ₂ As a result, the write voltage _Vw is added by these voltage differences, and silver is deposited (written). On the other hand, in the pixel (C ₁ , R ₂ ), there is no period in which the signal writing voltage pulse V _{sig of the} column electrode C ₁ overlaps with the selection voltage pulse V _sel of the row electrode R ₂ , and the signal writing voltage lower than the threshold voltage V _th. Only one of the pulse V _sig and the selection voltage pulse V _sel is applied. Therefore, silver deposition does not occur and writing to the pixel is not performed.
[0043]
After writing, the display can be memorized by opening or shorting both the column electrode and the row electrode. The row electrodes R _1, R _2, R ₃ in the voltage -V _e for erasing added at a predetermined timing, by so applied is positive voltage V _e in each pixel, the erase dissolved silver Done. The voltage V _e for the erasure is equal to or erase voltage V _{i @ th} at 4 before, set to a value slightly lower. If the erasing voltage V _e exceeds the erasing voltage V it, there is a _risk of coloring.
[0044]
In the above method, the time T _tw for displaying the time for depositing the silver pixel is T _w, when the number of row electrodes and N present, the entire panel,
T _tw = T _w × N
[0045]
Therefore, it takes time to multiply the deposition response time by the number of row electrodes. From experiments, it is known that the deposition response time _Tw is required to be about 0.3 seconds, and the longer the number of electrodes, the longer it takes to display. For example, when the number of row electrodes N = 100, the time T _tw for displaying the entire panel is 30 seconds.
[0046]
Further, the transient response characteristics of the electrodeposition type display element are as shown in FIG. 4, and each pixel has a strong characteristic mainly as a capacitor before the deposition of the metal, and the resistance value increases with the deposition. It has the characteristic of becoming smaller. Therefore, if there is sufficient metal deposition in the pixel, a large amount of current flows between the electrodes, resulting in a large potential drop. As a result, in the equivalent circuit shown in FIG. There is a problem that unnecessary current I _error flows and crosstalk occurs or contrast is lowered.
[0047]
Therefore, in the present invention, as a first configuration, pixel writing is performed in two stages: address driving for generating crystal nuclei and voltage application for additional deposition, thereby reducing the display time of the entire panel. FIG. 9 shows drive voltage waveforms in such a drive method.
[0048]
Also in this case, the address driving of each pixel is the same as the example shown in FIG. That is, a signal write voltage pulse V _sig smaller than the threshold voltage V _th is applied to each column electrode C ₁ , C ₂ , C _3, and a selection smaller than the threshold voltage V _th is applied to each row electrode R ₁ , R ₂ , R _3. The voltage pulse V _sel is added and the selection operation is performed in order from the top. At this time, a voltage (write voltage V _w ) (= V _sig −V _sel ) greater than the threshold voltage V _{th is} applied only to the pixel on which silver is deposited, and silver is deposited on the transparent column electrode.
[0049]
However, in this embodiment, it is not necessary to complete the write by the address drive, in order to may be generated crystals as a core, much crab than a time for applying a write voltage V _w to the example shown in FIG. 7 Can be shortened. Specifically, it takes about 1/10 of the writing time.
[0050]
After the end of the scan of the row electrodes in the address driving, to apply the threshold voltage V _th is less than the additional write voltage V _m to all pixels of the immediately panel. That is, the voltage −V _m is applied to all the row electrodes R ₁ , R ₂ , R ₃ . In the drawing, it is illustrated that the additional write voltage _Vm is applied after a predetermined time after the end of the address drive, but in practice, the additional write voltage _Vm is applied immediately after the end of the address drive.
[0051]
By applying this additional write voltage V _m, to add behavior to reliably fix the silver precipitation. When the additional write voltage _Vm is applied, the write voltage _Vw is applied at the time of address driving, and the precipitation is continued only in the pixel where the crystal serving as the nucleus is precipitated, thereby completing the write operation. On the other hand, in the pixel write voltage V _w at the time of address drive has not been applied, even precipitation does not occur by applying an additional write voltage V _m, the white state is maintained. This is also clear from the description of FIG.
[0052]
After writing, the display can be memorized by opening or shorting both the column electrode and the row electrode. Further, by applying an erasing voltage −V _e to the row electrodes R ₁ , R ₂ , R ₃ ... At a predetermined timing, and adding a positive voltage V _e to each pixel, silver is dissolved. Is erased. The voltage V _e for the erasure is equal to or erase voltage V _{i @ th} at 4 before, set to a value slightly lower. If the erasing voltage V _e exceeds the erasing voltage V it, there is a _risk of coloring.
[0053]
In the above driving method, a short writing time (address drive time) as T _a, referred to as a write address period. Further, the time for applying additional write voltage _{V m} and _{T m.}
[0054]
Current 4 - As the voltage apparent from transient response, the pixel write voltage V _w is applied which exceeds the threshold voltage V _th to the short address write time, short time even voltage once exceeds the threshold voltage V _th When applied, the silver precipitation nuclei are generated on the transparent electrode made of ITO or the like (column electrodes), then precipitated by applying a threshold voltage V _th is less than the voltage V _m progresses.
[0055]
To more quickly address the writing time T _a after the address drive ends, so that silver precipitation nuclei does not disappear, the voltage V _k close to the holding voltage V _ke is to be applied Is effective. Thereby, it is possible to keep the silver precipitation nuclei until the additional write voltage _Vm is applied even at _a short address write time Ta. Here, the voltage V _k does not need to be strictly set to the holding voltage V _ke , and may be a voltage that satisfies the condition | V _sig −V _k | <| V _th |.
[0056]
In the above driving method, the total time T _ta required for display of the entire panel is N, where the number of row electrodes is N.
T _ta = T _a × N + T _m
It becomes.
[0057]
Compared with the time T _tw (= T _w × N) required for writing in the driving method shown in FIG. 7, since T _a <T _w , T _ta <T as the number N of row electrodes increases. It turns out that the tendency of _w becomes strong.
[0058]
From the experimental results, it is known that T _w = 0.3 s, T _a = 0.03 s, and T _m = 3 s. For example, when the number of row electrodes N = 10,
T _ta = 0.03 s × 10 + 3 s = 3.3 s
T _tw = 0.3 s × 10 = 3 s
Although there is almost no change, when the number of row electrodes N = 100,
T _ta = 0.03 s × 100 + 3 s = 6 s
T _tw = 0.3 s × 100 = 30 s
[0059]
Thus, it can be seen that the driving method shown in FIG. 9 is advantageous. This tendency becomes more prominent as the number N of row electrodes increases, and the driving method shown in FIG. 9 relatively shortens the time for displaying the entire panel.
[0060]
In addition, by adopting the above driving method, not only _a short writing time _Ta is realized, but also precipitation is not sufficiently performed at the time of address driving, so that the resistance value of the pixel does not decrease and the impedance becomes high impedance. Accordingly, the amount of unnecessary current I _{error in} the panel equivalent circuit shown in FIG. 8 is reduced, the potential drop due to the resistance component of the column electrode and row electrode is reduced, and the write voltage is applied accurately. .
[0061]
Next, as a second driving method of the present invention, after the normal write is completed, the addition of regular threshold voltage V _th is less than the sustain pulse V _m, an example will be described to continue to maintain the display state.
[0062]
The electrolytic deposition type display element has a certain level of display memory, and by adding the holding voltage V _ke in the transient response characteristic shown in FIG. 4 or by opening the column electrode and the row electrode, The display can be held for several tens of minutes to several hours. However, in practice, the display contrast tends to decrease with time. Therefore, in this example, the sustain pulse _Vm is added to refresh (maintain) the display. FIG. 10 shows drive voltage waveforms in the drive method of this example.
[0063]
In the drive voltage waveform shown in FIG. 10, the write operation is the same as that shown in FIG. That is, a signal write voltage pulse V _sig smaller than the threshold voltage V _th is applied to each column electrode C ₁ , C ₂ , C _3, and a selection smaller than the threshold voltage V _th is applied to each row electrode R ₁ , R ₂ , R _3. The voltage pulse V _sel is added and the selection operation is performed in order from the top. At this time, a voltage (write voltage V _w ) (= V _sig −V _sel ) greater than the threshold voltage V _{th is} applied only to the pixel on which silver is deposited, and silver is deposited on the transparent column electrode to perform writing.
[0064]
A significant difference from the example shown in FIG. 7 is that the sustain pulse _Vm is applied after the write operation. At this time, it is not necessary to operate the signal pulse on the column electrode side, and for the reason described above, the silver is re-deposited only in the pixels where the silver is once deposited by the writing operation. The sustain pulse _Vm may be applied at an arbitrary interval, for example, at an interval of 10 minutes. Further, the sustain pulse V _m is sequentially scanned in this example, but the sustain pulse V _m may be applied to all the pixels at the same time. Also in this case, since silver is re-deposited only in the pixels where silver has once precipitated by the writing operation, the display can be maintained.
[0065]
Incidentally, application of the sustain pulse V _m, it is also possible to apply the driving method shown in the previous Fig. That is, after the address driving for a short time, the additional write voltage _Vm is applied to finish the write, and then the sustain pulse _Vm is applied. As a result, the short time display and the maintenance of the display quality are realized at the same time.
[0066]
【The invention's effect】
As is clear from the above description, according to the present invention, the address for depositing the pixels can be performed at high speed, and after that, the metal can be sufficiently deposited all at once. It can be shortened, and the total time required for display can be shortened.
[0067]
In addition, since the entire panel can be addressed with a high resistance value of the pixel, the potential drop due to electrode resistance is reduced, and an accurate address voltage can be applied to the pixel, realizing accurate precipitation display without crosstalk. can do. Furthermore, according to the present invention, it is possible to maintain an image for a long time by displaying a voltage once and then applying a voltage equal to or lower than a threshold voltage.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of an electrolytic deposition type display device.
FIG. 2 is a schematic perspective view showing a part of an electrolytic deposition type display device.
FIG. 3 is a waveform diagram showing a triangular wave voltage applied for examining a current-voltage transient response characteristic;
FIG. 4 is a characteristic diagram showing a current-voltage transient response characteristic;
FIG. 5 is a circuit diagram showing an equivalent circuit of a pixel.
FIG. 6 is a schematic diagram of a 3 × 3 pixel panel.
FIG. 7 is a waveform diagram showing drive voltage waveforms in a method for driving an electrolytic deposition type display device.
FIG. 8 is an equivalent circuit diagram showing how an unnecessary current I _error flows.
FIG. 9 is a waveform diagram showing a driving voltage waveform in a driving method in which additional deposition is performed after address driving.
FIG. 10 is a waveform diagram showing drive voltage waveforms in a drive method for maintaining display by applying a sustain voltage after writing.
[Explanation of symbols]
1 Transparent substrate, 2 Column electrode, 3 Base substrate, 4 Row electrode, 5 Polymer electrolyte

Claims (3)

When displaying an image by applying a voltage at each pixel by electrodes arranged in a matrix, depositing and dissolving the metal,
Selectively applying a voltage equal to or higher than a threshold voltage, which is a deposition overvoltage, to a predetermined pixel for depositing metal to precipitate a core crystal on the predetermined pixel;
Applying a voltage lower than the threshold voltage to all the pixels at the same time , further depositing metal on the predetermined pixels on which the nuclei are deposited, and writing to the pixels;
After writing to the pixel, applying a voltage lower than the threshold voltage to hold the writing state; and
A display element drive method including : Voltage for holding the write state, Ru added intermittently until the erase voltage is applied
請 Motomeko 1 driving method of a display device according. Voltage for holding the write state, Ru added with a predetermined pulse width
請 Motomeko 2 driving method of a display device according.

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