JPS58223182A - Drying of electrochromic display element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving an electrochromic display (hereinafter abbreviated as ECD) element, and more specifically, the present invention relates to a method for driving an electrochromic display (hereinafter abbreviated as ECD) element, and more specifically, six electrodes are formed by mixing WO3 with graphite and a transition metal oxide. This invention relates to a driving method that uses a counter electrode to drive an ROD element with a constant current.

Conventionally, the element structure and driving method of a 11u(!D element) having a carbon-based (a mixture of carbon and at least one type of transition metal oxide) counter electrode were shown in FIG.

In FIG. 1, a transparent electrode (2) is placed on a transparent front substrate (1),
(8) is placed, and on top of that is an EC layer (4) such as WOa.
, (5) is listed. The back substrate (6) is provided with an H-contact electrode (
8) is listed. In the space created by the front substrate and the back substrate, an electrolytic solution (9) containing ions such as H→-6L, 10, Na10, Ag10, etc., which can color the EC material, and a background plate ()
0), combine the peripheral sealing material (11) as shown in Figure 1.
) constitutes an EOD cumulus.

A power supply (12) to drive this type 0ECD element.
, (Prepare 131 (a battery may be used as shown in Figure 1). Take out the conductor from the place where the two power supplies are connected 1-5 and connect it to the opposite type 4ft (7). When using constant current drive A constant current circuit (15) is provided between the display electrode and a power source lower than the counter electrode (α2 in this figure). A conductive wire is drawn out from the display electrode and connected to switch Oa or a semiconductor switch having an equivalent function. Don't make it easy, first.
Only the display electrode on the left side of the figure will be explained. A switch applies a positive voltage (p+ position) and a negative voltage (
A floating state can be created by applying current (current) (P3 position) and by setting P2 position. Note that in actual circuits, this switch and constant current circuit are often constructed as one unit, but here we will explain their functions separately.

Next, a method for driving the D element shown in FIG. 1 will be explained. If a display segment that is in the colored state is to be bleached, the bleaching voltage vb can be set by connecting the switch to the P8 position.
(In this case, the battery (13+) is applied or a decoloring current (which may be a constant current) is applied for a certain period of time Tb.
After the elapsed time, move the switch to the P2 position. Next, when coloring the display segment to be decolored, connect the switch to the P3 position to flow a constant current Ic defined by the constant current circuit, and after a certain period of time 'rc, turn the switch to the P3 position.
Set it to the 7th position. In an actual display, there are a plurality of display segments, so the desired display pattern can be obtained by simultaneously performing the above-mentioned coloring and decoloring. The displayed coloring density is mainly determined by the injection rate (current IC x time Tc)
Determined by Coloring control is performed by changing the setting of the current value Ic, by changing the writing time 're, or by a combination of both.

In the conventional ROT constant current driving method, the current value IC and the coloring time 'rc are set to constant values, and a constant amount of charge is injected into the EOD display segment to color it at a predetermined density. E
The temperature dependence of the response speed of a CD is large, and the response speed tends to be particularly slow at low temperatures. Furthermore, ECDs are required to have a wide operating temperature range, and displays are required to be sufficiently colored even at low humidity. In order to meet this requirement, conventional constant current drive has a coloring time Tc
The current value IC was set to be long and the current value IC to be low in order to maintain the color density at low temperatures. This takes advantage of the phenomenon that when a constant electric current is injected into the display electrode and the current value is lowered, the potential difference between the display electrode and the counter electrode becomes smaller.
This is because the power supply voltage can be low, and the device life can be maintained for a long time. Therefore, the coloring time was set for low temperatures, and the response speed at around room temperature, where the usage time would be the longest, was slower than the original response speed of FiOD at that temperature.

The present invention eliminates the drawback that the response time of the KOD is slower than the original response time of the constant current drive method in the temperature range of room temperature or higher, and eliminates the advantage of the constant current drive method (between segments). This was done in order to maintain a constant current drive system with a small variation in the color density of the ambient temperature (
current flow by detecting the element temperature) or electrode potential.

The purpose of this invention is to provide a driving method that changes the combination of X times're and keeps the amount of injected charge constant.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram in which the present invention is applied to the ECD element shown in FIG. 1. The EOD device shown in FIG. 2 is the same as the device shown in FIG. (6), a back electrode (8) placed on it, a carbon-based counter electrode (7) electrically connected to it, an electrolyte (9), a background plate (1o), and a peripheral sole Ql). As a power source, a coloring power source (121° decoloring power source 03) is prepared, and the connection point of both power sources is connected to the counter electrode.The positive terminal of the decoloring power source (13) is connected to the switch (14
), the negative terminal of the coloring power source (12) is connected to the constant current circuit (15), and the other terminal of the constant current circuit is connected to the P5 position of the switch 04). switch a
The P2 position of a is not connected and is in an open state, which corresponds to a floating output in the case of a semiconductor switch. By this wiring, the terminal 4' of the switch (14) is turned off, and the display electrode can be selected to be in a positive voltage application, a negative constant current application, or a floating state with respect to the counter electrode. 1. A control unit (16) that detects the ambient temperature and determines the current value to be passed to the display electrodes and the corresponding coloring time.
is provided.

Next, a method of driving the EOD element shown in FIG. 2 will be explained. When coloring a display segment, by setting the switch Oa to the P8 position, a constant current Ic is passed through the display electrode to the counter electrode for a certain period of time Tc, and the display segment is colored to a certain density. Thereafter, the switch is set to P2 position to maintain the floating state and the colored state. The display coloring density is mainly determined by the product (charge amount) of the set current value Ic and the coloring time Tc.

To erase the colored segment, switch 04
) to the P1 position for a certain period of time.

As the two-color current IcO value, a preset current value IC is determined based on the detection result of an ambient temperature sensor, a temperature sensing element such as a semiconductor element, etc. Further, the control section 06) calculates the coloring time corresponding to the current value, and controls the constant current circuit section 09 to carry out the coloring process of the display section.

With this driving method, the coloring current Ic and the coloring time Tc can be changed continuously in response to the ambient temperature, or even if they are divided into finite ranges and changed stepwise, this is practically impossible compared to the continuous type. It is comparable in terms of cost and can be lowered in cost.

In addition, although the current and current values of a constant current circuit can be determined by detecting the ambient temperature as described above, it is also possible to determine the constant current by detecting changes in the display electrode potential when coloring the decolored segment with constant current and current. It is possible to use a configuration with zero power from the control circuit that determines the current level. Figure 3 shows the above control circuit (I7
) is shown.

When the ECD is driven by a constant current method, the change in the electrode potential during coloring is shown in FIG. 4. The graph shows the potential change when the display segment is colored at a constant current value of 0 and the foot time To, using the ambient temperature as a parameter. The curve in Figure 4 a shows an example of constant current driving at a lower temperature than the curve in b, and the lowest potential of each curve is Vami, n, Vbmi.
Do something. This lowest potential tends to decrease as the temperature decreases, and when driving with constant current at low temperatures, it is necessary to keep the power supply voltage high.

However, when a short load is injected into the ECD at a constant current at the same temperature, the smaller the current, the smaller the absolute value of the lowest potential. Therefore, constant current is possible without depending on the cylindrical power source IT pressure. Figure 5 shows that when the injection-1 flow rate is different, such as in the case of injection (C in the figure) and small (d in the figure), the lowest potential is Vcmin <
The relationship between Vdm1n is recognized.

Using the above characteristics of constant current drive of EOD, Vm
It is possible to detect the in-city position and drive it with a current value that is preset for that value.

The control scheme shown in FIG. 3 operates as follows. If the potential detection circuit detects a potential lower than the set Vmin i (during constant current drive), the control circuit activates the constant current circuit to reduce the coloring current value IC and lengthen the coloring time at the next display change. In general, at low temperatures, the voltage between the display and counter electrode terminals increases, resulting in disadvantages such as shortening the element life. Therefore, in constant current drive, constant current performance is maintained by reducing the current level. In this circuit, the current value level can be varied continuously or in steps.

In order to make the above function work, it is possible to have a dedicated reference electrode as the detection target electrode, or in the case of an 8-figure numeric display, the θ (lower left) segment of the lowest digit can also be used as the detection electrode. be. When the θ segment is displayed numerically,
Since this is the segment that changes the most, it is suitable as a detection segment.

Furthermore, in the description of the present invention, it has been described that constant current driving is used for coloring. However, even in the case of decolorization, it is no problem to use a constant current. In addition, in the case of erasing using a constant current, the erasing time is set to be longer than the calculated value in order to eliminate undesirable erased parts.

In addition, in the present invention, a power source was used for decoloring, but by selecting a transition metal oxide to be mixed with carbon, which is a counter electrode material, or by combining them, for example, by using carbon and MnO2, carbon threads can be used. By changing the potential of the counter electrode and setting it in a more positive direction than the display electrode, the color can be erased simply by shorting the direction electrode and the colored display electrode. According to this method, a decoloring power source is not required, and operation using a single power source is possible.

As described above, according to the present invention, since the display electrodes are colored by constant current driving, it is possible to reduce the unevenness of coloring density between segments.In addition, in the constant current method, if the operating temperature range is set wide, the response speed is fast at room temperature and high temperature. However, in the present invention, by incorporating temperature detection or potential detection of IT-colored electrodes, the Magic Flute and flow drive method simultaneously achieves three things: fast response speed and high-quality display with less display temperature unevenness. It's possible.

Further, since the large inrush current that occurs in the constant voltage method during constant current driving does not occur, it has the effect of lengthening the life of the display element.

In addition, the method of changing the current value level of the υ constant current circuit using potential detection has the effect of automatically responding to variations in response speed of the element and changes over time due to long-term use so that a constant concentration is displayed. There is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional constant current drive system. FIG. 2 is an explanatory diagram of a driving method incorporating the temperature detection circuit of the present invention, and FIG. 3 is an explanatory diagram of a driving method incorporating the potential detection circuit. FIG. 4 is an explanatory diagram of an example of change in display electrode potential due to temperature during constant current driving. Figure 5 shows an example of the change in display electrode potential when the ilI current value is changed during constant current driving.
This is a clear diagram. 1... Display electrode substrate 2.3... Display electrode 4.5... Display KO electrode 6... Back substrate 7... Counter electrode 8... Back electrode 9... Electrolyte 10 ... Background plate 11 ... Seal material 12.13 ... Power supply 14 ... Switch 15 ... Constant current source 16.17 ... Control circuit agent 1) Akira agent Hagiwara Ryo - Kaya) Gekime 2) 4 Bud 3 Use 7

Claims (1)

[Scope of Claims] (1) A display electrode substrate comprising at least a transparent electrode formed on a transparent substrate and an electrochromic material layer formed on the transparent electrode, and at least one type of transition metal in graphite. A counter electrode made of a mixture of oxides, a back substrate formed with an electrode so as to be electrically connected to the counter electrode, and an electrolytic solution containing ions capable of coloring the KO material layer sandwiched between the two substrates. An electrochromic display, characterized in that an electrochromic device is driven by a constant current to color the display, the electrochromic device having an ability to change the current value level of the constant current with respect to the ambient temperature of the electrochromic device. Driving method of element. (2) The method for driving an electrochromic display element according to claim 1, characterized in that the humidity f% dependence of the sensor or the element in the drive circuit is used as the ambient temperature detection means. (8) A method for driving an electrochromic display element according to claim 1, characterized in that the current value level of a constant current is changed by detecting a potential difference between a counter electrode and a display electrode that is becoming colored. . (4) Counter electrode and display electrode 9 digit 8 with the most display truncations
4. A method for driving an electrochromic display element according to claim 3, characterized in that a potential difference between the segments is detected. (5) A method of driving a display element using a single-electromechanism, in which the display element is driven at a lower potential than the counter electrode when coloring, and short-circuited with the counter electrode when decoloring.