JPS5916268B2 - electrochromic display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device to which electrochemical coloring/decoloring phenomenon (electrochromism) is applied.

As an EC display device using an electrochromic (hereinafter abbreviated as EC) material, for example, one whose cross-sectional structure is shown in FIG. 1 is known.

In FIG. 1, a display substrate 1 having a display electrode 3 and a counter substrate 2 having a counter electrode 4 are arranged in parallel with a spacer 5 in between, and an electrolyte 6 is sealed between them. An EC layer T is provided on the pattern portion of the display electrode 3, and the remaining portion is covered with an insulating layer 8. E
When a vapor deposited film of tungsten oxide WO3 is used as the C layer 1, a sulfuric acid glycerin solution is used as the electrolyte 6 (US Pat. No. 3,704,057). Further, when a viologen compound is used as the EC material, a potassium bromide solution is used as the electrolyte 6, and the EC material is dissolved in the electrolyte 6 as viologen bromide. When a voltage is applied using the display electrode 3 as a cathode, viologen bromide is reduced to a colored product, which is deposited on the patterned portion of the display electrode 3 as an EC layer T (US Pat. No. 3,806,229). Tungstate or molybdate solutions are also known as this type of solution-type EC materials (IBM, Tech
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VOI, 17 Ma 4, 1974). In these EC display devices, the display electrode 3 is used as a cathode, and the counter electrode 4 is used as a cathode.
When a DC voltage is applied to the anode, the pattern area becomes colored, and when the polarity of the voltage is reversed, the pattern area becomes colorless.
When observing this from the display substrate 1 side, display substrate 1
And the display electrode 3 is made of a transparent material.

On the other hand, when observing from the opposite substrate 2 side, the opposite substrate 2
, the counter electrode 4 and the electrolyte 6 are all made of transparent materials. In this case, it is also possible to provide a light source behind the counter substrate 2 and observe it from the display substrate 1 side as a transparent display device. Further, the counter electrode 4 does not necessarily need to be provided on the counter substrate 2 side, and as shown in FIG.
It can also be provided at the periphery (outside the field of view). Figure 2 is E
FIG. 3 is a diagram showing the relationship between color density and driving voltage of a C display device.

The voltage applied between the counter electrode and the display electrode is V. If the voltage exceeds this value, color development is observed, but the density increases with the voltage.If the voltage is V1 or V2, the density C1 or C2 will be obtained after a certain period of time T2, respectively. FIG. 3 is a diagram showing the relationship between color density and application time when the driving voltage is kept constant (corresponding to V in this case). Since the color density rises rapidly in the initial stage and gradually saturates, the time T2 to obtain the density C2 is much longer than the time T1 to obtain the half density C1. From the viewpoints of durability of the display device, reliability of the drive circuit, and power consumption, it is preferable that the drive voltage be as low as possible.
It is also necessary to obtain sufficient color density required for display in a short period of time, and in the end, the most efficient driving voltage is adopted in consideration of these conditions. By the way, when displaying various information using such an EC display device, for example, the second
By performing gradation display using different color densities as shown in C1 and C2 in the figure, the amount of displayed information can be doubled.

However, if a conventional EC display device were to perform this grayscale display, two power supplies, for example, 1 and V2, would be required as drive voltages, which would not only complicate the circuit configuration but also cause the disadvantage that the response speeds would differ. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an EC display device that can display gradations using a single power source, thereby doubling the amount of information displayed.

Another object of the present invention is to provide a display device with high response speed. Still another object of the present invention is to provide a display device that can obtain high color density even at a low driving voltage. For the above purpose, in the present invention, segment-type display electrodes are provided on both the display substrate and the counter substrate, and their patterns are arranged in an overlapping manner.When one is driven, a light coloring density C1 is obtained, and when both are driven, a light coloring density C1 is obtained. A deep coloring density C2=2C1 is displayed.

Examples will be described below with reference to the drawings.

FIG. 4 is a cross-sectional view showing an embodiment of the EC display device of the present invention, in which the display substrate 1 and the counter substrate 2 are provided with display electrodes 3, 3' and EC layers 7, 7', respectively.
The counter electrode 4' is provided at the periphery of the display device. In addition,
As the counter electrode, a metal wire 4'' may be stretched around the periphery of the display device, and one end thereof may be passed through the spacer 5 to serve as a lead terminal.In this device, the counter electrode 4/42 may be used as an anode. and display electrodes 3 and 3
If the EC layers 7 and 7' are simultaneously driven as cathodes, the EC layers 7 and 7'
However, if the display substrate 1, display electrode 3, and electrolyte 6 are all made of transparent materials, the colors of the EC layer 7 and r can be observed simultaneously in a superimposed manner. Now, if the driving voltage is set to V1 in FIG. 2, C1+C1=
The concentration of C2 is observed, and where there is no overlap, the concentration of C1 is observed.

Further, when one of the display electrodes is driven, a concentration C1 obtained by the voltage V1 is observed. From the above explanation, it is clear that the single driving power supply V1 can display gradations corresponding to the color densities C1 and C2.

It is also clear that the sufficient color density C2 required for display can be displayed using a voltage V1 that is much lower than the originally required voltage V2.

Furthermore, if the driving voltage is set to V2 and the pair of display electrodes 3 and 3' are driven, each electrode will have a concentration C1 during the application time T1 in FIG. 3, and this will be observed as a concentration C2 when they overlap. , it is also clear that the response can be achieved in a much shorter time than the originally required application time T2.

Next, an example will be described in which the gradation display according to the present invention is applied to the second display of a digital display type electronic watch.

In digital display watches that display the time in numbers,
A method of displaying seconds at 10 second intervals as shown in FIG. 5C by sequentially driving six display elements 11 from the left as shown in FIG. 5A is known as a 10 second interval seconds analog display method. . If the present invention is applied to this, it is possible to display as shown in FIG. 2D using three display bodies 12 as shown in FIG. In other words, in the present invention, each display body has two shades of light and dark.
It is clear that since the information is driven in the same way, the displayed information content is doubled, and that even with three displays, six displays of information can be displayed. FIG. 6 is a diagram showing a day-of-day display section in a conventional digital display timepiece.

The day of the week display section includes a fixed display body 13 on which day symbols (in this case, kanji for Monday, Tuesday, Wednesday, etc.) are printed on a part of the display device, and are placed near each symbol. The day of the week is indicated by sequentially driving the drive display 14. This device has a disadvantage in that it is undesirable in terms of design because the printed fixed display 13 is always displayed even when the day of the week display is not required. FIG. 7 shows an example in which the shading display according to the present invention is applied to the day of the week display section. Six of the seven display elements 15 are displayed in a light color, and only the remaining one is displayed in a dark color. is increasingly being pointed out. Furthermore, the shading may be reversed. In this case, instead of using the same pattern for the seven display elements 15, a day-of-the-week symbol pattern is used so that the day of the week can be directly read as shown in FIG. 8 or 9, and such a pattern is made to correspond to each day of the week. Place 7 pieces, display one of them in dark color,
If the remaining six are displayed in a gray color, the day of the week will be displayed more clearly, but even with the same pattern as shown in FIG. 7, the day of the week can be determined if it is agreed that each week starts on Monday.
It is also possible to perform analog display at 10 second intervals using a display unit as shown in FIG. 7 in a manner as shown in FIG. 5c. In this case, the day of the week display shows seven indicators, one of which indicates the day of the week in a dark color, and the seconds display shows six indicators, of which one to six indicate the day of the week. The seconds are displayed in dark color. Since the number of display bodies used for display (seven or six) is displayed in at least a light color, confusion between the day of the week display and the seconds display is prevented. Furthermore, if you do not need these displays, you can erase all of them, so there is no sense of discomfort in the design. FIG. 10 shows an example in which the gradation display according to the present invention is applied to the time display of a clock.

In this watch, the hours, minutes, and seconds are displayed on the display section 21,
22, 23, but the hours and minutes are in dark colors,
Seconds are now displayed in a lighter color. In EC display devices, power is consumed to rewrite the display, but EC
Since the image has a memory property, there is no power consumption during display. Therefore, if readability is sacrificed to some extent, and only the second display, which is frequently rewritten, is displayed in a dim color, power consumption can be greatly reduced. FIG. 11 shows an example in which the gradation display according to the present invention is applied to correction of a clock display.

When starting to use a digital display clock that has stopped, or when correcting a display that has gone awry due to an incorrect operation, first operate the correction digit selection button 24 to select the correction digit, and then operate the correction button 25 to correct it. Corrections are made by sending signal pulses to advance the display. In the figure, the 10 second digit 26 is indicated by a dimmed color to indicate that it is the selected correction digit. FIG. 12 shows an example in which the shading display of the present invention is applied to a competition watch.

Timing starts when the start button 31 is operated, but
The intermediate time during timing is displayed in light color as shown in FIG. The figure shows 2 hours 38 minutes 54 seconds. A similar gradation display can also be applied to negative number display on electronic desktop calculators. As explained above in the EC display device according to the present invention, it is possible to perform grayscale display using a single power source, and the information content displayed using a limited display body can be doubled.

Furthermore, it can be driven to a sufficient color density with a lower voltage than conventional methods, and the response speed can be much faster. Therefore, it has been widely applied to digital electronic watches, calculators, and other display devices, and its effects are great.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the cross-sectional structure of a conventional EC display device, Figure 2
3 and 3 are diagrams showing the relationship between color density, driving voltage, and application time in a general EC display device, FIG. 4 is a diagram showing a cross-sectional structure of the EC display device of the present invention, and FIG. A diagram showing an example of applying the gradation display according to the invention to the second display of a digital display watch, FIG. 6 is a diagram showing a conventional day of the week display method, and FIGS. 7 to 9 are for explaining the day of the week display method according to the present invention. and FIGS. 10 to 12 are diagrams showing display examples in other embodiments of the present invention. 1, 2... Electrode substrate, 3, 3... Display electrode, 4Z4''-... Counter electrode, 6... Electrolyte, 7, 7''... ... Electrochromic material layer (EC layer)
, pattern section.

Claims (1)

[Claims] 1 A pair of electrochromic display electrodes having display parts of the same shape arranged in completely overlapping positions and exhibiting the same coloring characteristics, a transparent electrolyte interposed between the pair of electrochromic display electrodes, and a transparent electrolyte interposed between the pair of electrochromic display electrodes; A counter electrode in contact with the electrolyte is provided between a pair of transparent electrode substrates, and one or both of the pair of electrochromic display electrodes is arbitrarily selected and driven by a single power supply voltage. An electrochromic display device comprising: