JPS6132671B2 - - Google Patents

Description

[Detailed Description of the Invention] <Overview> The present invention relates to an electrochromic display device (hereinafter referred to as ECD) that uses a substance whose optical absorption characteristics in the visible region reversibly change when an electric current is applied. The present invention relates to a cell structure and a driving method when performing display.

<Prior art> A substance that has two types of optical absorption characteristics in the visible light region, transparent and colored, and can reversibly select between these two states using electrical energy;
In other words, many electrochromic substances (hereinafter referred to as EC substances) are known. Typical of these materials are an amorphous tungsten oxide film (WO ₃ ) or an amorphous molybdenum oxide film, and various other transition metal oxide thin films are known. (USPat.No.2319765 Talmey or
USPat.No.3521941 Deb et al) or these
It is already known that EC materials can be patterned and two different optical properties can be reversibly selected through electrical control to display arbitrary characters, symbols, patterns, etc. (US Pat. No. 1068744 or the patent invented by Deb et al mentioned above) The cell structure of an electrochromic display element can be either a type in which the ion supply source is a liquid or an electrolyte (as in the Talmey patent mentioned above) or , a type using an inorganic insulating film (Deb's patent mentioned above) or a type using a solid electrolyte (US Pat. No. 3712710)
Castellion et al., etc. are known, but since the solid-state type has poorer operational stability than the electrolyte type, the liquid type is considered to be closer to practical use. As the electrolyte, sulfuric acid gel (USPat.
No. 3708220 MDMeyers et al 1973) or acetonitrile or propylene carbonate with lithium perchlorate (US Pat.
No.3704057 LCBeagle 1972) has been proposed. The problem of receiving and receiving charges on the counter electrode can be solved by providing an EC material layer (US Pat. No. 3819252
RDGiglid et al or USPat.No.3840287
Witzke et al special show 50-5089).

The background problem at that time was to disperse the pigment in the electrolyte to make it optically opaque (the RDGiglid mentioned above).
et al. patent) or by inserting a plate that allows ions to pass through but is optically opaque (US Pat.
No.3892472 Giglia or USPat.
No. 3944333 Leibowitz).

As the structure of the display electrode, a 7-segment numeric display cell structure is shown (US Pat.
No. 3827784 Giglia et al, Japanese Patent Publication No. 47-13891). Alternatively, an insulating layer is provided to protect the edges of the display EC material layer (US Pat. No. 3836229 Eric
Saurer) then USPat.No.3892472 or
US Pat. No. 3944333) shows a 7-segment numerical display cell.

The cell structures of the numeric display ECDs that have already been proposed will be summarized and explained. FIG. 1 shows an exploded bird's-eye view of the ECD cell, and FIG. 2 shows a sectional view taken along the E-L plane in FIG. 1. In FIGS. 1 and 2, 1 and 2 are glass substrates, 3 is a display part (EC material), 4a is an electrode extension part (transparent conductive film), 5 is an electrolytic solution and a counter electrode masking agent (porous pigment holding filter), Reference numeral 6 denotes the EC layer of the counter electrode (a layer that facilitates the transfer of charges at the interface).This layer is usually made of the same material as the display part, and is colored before forming the cell. 7 is a counter electrode extension part (conductive material), 8 is an electrolytic solution, 9 is a sealing part and spacer, and 10 is an insulating layer (extension part protection). The EC cell described here includes a substrate 1 electrode, a lead-out part 4,
Since the display section 3 is constructed to be optically transparent, the counter electrode hiding layer 5 is visible when viewed from the bottom in FIG. Therefore, when an electric field is applied from the DC power supply E through the polarity switch S so that the electrode 4 becomes negative and the electrode 7 becomes positive, the display part 3 changes from transparent to blue (in the case of WO ₃ or MoO ₃ , this will be used as an example below). change to). If the electrode 4 is selected, numbers can be displayed in blue against the white background layer 5.

Although the ECD configured as described above has good reliability and can be a display element with low viewing angle dependence and high contrast, the ECD has a fatal defect in manufacturing. In other words, manufacturing the display section 3 and the insulating section 10 flush with each other as shown in FIG. 2 is difficult because the display section 3 and the insulating section 10 are constructed separately, so there is no problem with the alignment between them. It is possible. Therefore, the actual structure is as shown in FIG. 3a and b.

That is, in FIG. 3a, the entire surface of the transparent electrode extension part is covered with the insulating film 10 and is not in direct contact with the electrolyte, so the extension part 4 is fully protected, but part of the display part 3 is The area (blacked out area a) is also coated. Therefore, when the display section 3 is operated and colored, the factors (charges) that contribute to this coloring are diffused, and as a result, part a is also colored.
Even if the display section 3 is made transparent, this colored section cannot be erased because it is covered with an insulating film, resulting in a
part cannot be electrically controlled.

On the other hand, in the structure shown in Figure 3b, there are no parts that cannot be electrically controlled as described above;
Part of drawer part 4 (blacked out part b)
is exposed and not insulated. When an electric field is applied for electrical control, an electrochemical reaction occurs in the shaded area b, causing destruction of the transparent electrode or decomposition of the electrolyte.

<Description of the Present Invention> As described above, the conventional ECD has a transparent display electrode, and displays with the counter electrode hiding agent provided inside the ECD cell as the background. They are all ECDs with so-called positive type display. Moreover, manufacturing an ECD with a positive type display is extremely difficult when considering mass production. The present invention solves all of these drawbacks and relates to an ECD electrode structure that can be easily mass-produced.
That is, the problem of mass production is solved by changing the positive type display to a negative type display.

FIG. 4 shows a bird's eye view of the display electrode when the ECD cell according to the present invention is disassembled. Further, FIG. 5 shows a sectional view at C and D in FIG. 4. In Figures 4 and 5, 11 is a glass substrate, 12 is an EC
Material layer (EC material layer is WO ₃ or MoO ₃
(generally used) (fourth layer), 13 is a transparent conductive film (first layer), and 14 is a second transparent conductive film (third layer).
layer), these films 13 and 14 are insulating layers (second layer)
15 and electrically insulated. Here, the film 14 serves as a background electrode for characters, and the film 13 serves as a display electrode. In other words, the membrane 13 is a segment part
It is an electrode that controls the EC layer, and the film 14 is the background part EC.
These are the electrodes that control the layers.

The manufacturing process of the display electrode having the above-described structure will be explained step by step with reference to FIG. The manufacturing process of the display electrode according to the present invention will be explained below with reference to FIG.

1. A transparent conductive film 13 is patterned on a smooth glass substrate 11 by a well-known method. That is, membrane 1
3 to form a display segment portion and an electrode extension portion. (Fig. 6a) 2. Using a positioning jig similar to that used in step 1, photoresist or etching resist 21 is patterned to cover the display segment and electrode terminals, and when forming the insulating film. mask. (FIG. 6b) 3. Using the resist mask formed in step 2, an insulating layer 15 (second layer) is formed on the entire surface of the substrate,
Furthermore, a transparent conductive film layer 14 (third layer) is formed on the entire surface of the substrate.
form. In this case, the formation of the insulating layer 14 must be performed particularly carefully to form a dense layer in order to prevent vertical leakage. (FIG. 6c) 4. Peel off the resist mask 21 and pattern the third layer 14 and second layer 15. (Fig. 6d) 5. Cover only the terminal portion of the entire surface of the substrate with a metal mask, and form the EC material layer 12 (fourth layer) on the entire surface of the substrate. (FIG. 6e) Through the above steps, the display electrode according to the present invention is easily completed. In the display electrode structure according to the present invention, the extended portion of the first layer transparent electrode is electrically insulated from the fourth layer EC material layer and the third layer transparent electrode by the second layer insulating layer 15; , background layer
The two main points of the EC layer (hereinafter referred to as background layer) are that it can be electrically controlled by the third transparent conductive film layer.

The structure of the ECD cell according to the present invention is the same as that shown in FIG. 2 except for the display electrode (background electrode) and the structure of the counter electrode side and the counter electrode hiding layer, so the explanation thereof will be omitted. Here, since the ECD according to the present invention is of a negative type, the counter electrode hiding layer 5 may be of any color as long as it differs from the EC material layer in at least one of hue, saturation, and lightness and clearly differs in color sensation. Can be used.

As already mentioned, there are two types of EC materials with optical absorption characteristics in the visible range, and it is possible to arbitrarily select between the two using electrical methods or other methods. Among the EC substances, WO ₃ or MoO ₃ , which are given as examples, can be found in a transparent state (hereinafter referred to as OFF) or in a blue-colored state (hereinafter referred to as OFF).
It is well known that it has two types of optical absorption characteristics: ON). It is also known that this ON-OFF state can be reversibly selected as desired using electricity, light, heat, or the like. Furthermore, it is well known that the color density of this ON state can be selected in the same way. Therefore, in the embodiment shown in FIG. 5, the entire EC material layer 12 covering the entire surface of the cell can be driven arbitrarily using the display electrode 13 and the background electrode 14. When displaying in this embodiment, first a negative voltage is applied to the electrodes 13 and 14, and the EC layer 12 is
Color them all blue. In this case, even if voltage application is stopped, it is maintained due to its memory effect. The EC material layer 12 corresponding to only the segment portion necessary for display is electrically connected using the electrode 13.
By turning it off and optically exposing the counter electrode hiding layer 5 from this part, characters can be displayed as desired. Then, by reversing the voltage, the original ON state is returned. It is already known that the color density of the EC membrane is proportional to the amount of charge flowing.
By controlling the applied voltage and time, it is easy to change the color density to the same as the initial color density.

In the EC cell configured in this way, there is no part where the transparent conductive films 13 and 14 are in direct contact with the electrolyte, such as the part b shown in FIG. The problem of diffusion of factors into parts not in direct contact with the electrolyte does not occur because the cell according to the invention is constructed in such a way that all of the EC material layers are electrically controllable.
On the other hand, when the display section is in the OFF state, the coloring factors diffuse from the surrounding colored sections.
Since it can be turned off electrically, it does not prevent display. Moreover, problems caused by the memory properties of EC materials can be solved as follows. The memory properties of EC materials are theoretically infinite, but in reality they are attacked by oxidizing substances contained in the electrolyte (for example, dissolved oxygen or substances by-produced during electrolytic reactions). The color will fade over time. For this reason, a difference in optical density occurs between the display electrode (newly turned on) and the electrode that was in the memory state (mainly the background electrode). A method for solving this drawback is a driving method in which the display electrode and the background electrode, which are in the ON state during memory, are electrically shorted to each other so that the optical densities thereof are made the same.
This driving method has been filed by the present applicant as a "method for driving a display device" (Japanese Patent Application No. 52-38631).

According to this method, it is reported that by short-circuiting electrodes with different optical densities in a colored memory, the difference in optical density can be eliminated in about 1 second.

<Preferred Embodiment> As described above, by changing the display type to a negative type, it has become possible to produce an ECD that is highly suitable for mass production. Here, specific examples will be shown below.

Example 1 (FIGS. 2 and 6) Glass substrates 11 and 2 are smooth glass plates having a thickness of 1 mm to 3 mm, and are commercially available from Matsunami Glass Co. or Asahi Glass Co., Ltd. The substrate 11 has a display electrode and a background electrode. The transparent conductive film 13 is an In ₂ O ₃ film doped with SnO ₂ and is obtained by electron beam evaporation. The film thickness is 1800~2000Å and the resistance is 20~30.
Ω/□. The obtained transparent conductive film is patterned by a well-known photoetching method using a positive type resist (AZ 1350 manufactured by Shitsupo Play).
Etching of the In ₂ O ₃ film was carried out by heating a mixture of equal amounts of 42Be' ferric chloride solution and 12N hydrochloric acid aqueous solution to 40°C. Resist is printed on only the display portion and the terminal portion of the transparent electrode obtained in this manner by screen printing. The printing machine is Newlong LS, the 20 screen plate is Tetron 300 Metsuyu (manufactured by Metsuyu Kogyo),
The etching resist was Nazda #300 (Nazda Corp., USA). After drying the etching resist at 120° C. for 20 minutes, 2 μm of SiO ₂ was deposited using the vacuum deposition method, and a transparent conductive film was deposited in the same vacuum deposition machine as described above in which an insulating layer 15 was provided. Thereafter, the resist was removed from the substrate while applying ultrasonic waves in Triclean (Kishida Kagaku). Only the terminal portions of this substrate are masked, and a WO ₃ film of 5000 Å is deposited by a resistance heating method to form the EC material layer 12. As described above, the display electrode side substrate was obtained. For the other glass substrate 2, an In ₂ O ₃ film 7 having a thickness of 1800 to 2000 Å and a WO ₃ film 6 having a thickness of 5000 Å are formed thereon to serve as a counter electrode. 9 is a sealing spacer and a sealing material, and a 1 mm glass plate (Matsunami Glass Co., Ltd. thin plate glass) is used as a spacer, and the aforementioned display electrode and counter electrode are made of epoxy resin (e.g. R・2401, HC-1bO Somar Kogyo).
Heat seal at 120℃ for 30 minutes. 5 is a counter electrode hiding layer, in this case white porous alumina ceramics (C-
3 made by Nippon Toki). In the cell prepared as above, ^1.0M /
A LiClO ₄ .gamma.-butyrolactone solution (all manufactured by Kishida Chemical Co., Ltd.) was injected. The injection port was sealed by pasting a glass disk (Matsunami Glass) with room temperature curing epoxy (CS-2340, Cemedine).

As mentioned above, negative type ECD with white letters on a blue background
can be completed, when turning on the 7-segment ECD WO ₃ membrane -IV・500msec, when turning it off +
Although the device has been operated for one year at room temperature under the condition of 2.3 VI seconds memory time of 60 minutes (all ON electrodes including the background electrode are shorted during this period), no difference in optical density was observed between the background layer and the driving layer. Nakatsuta.

Example 2 In the formation of display electrodes, 2 and 3 in FIG.
An ECD cell was produced by differing from Example 1 only in the process and the counter electrode hiding layer 5 as described below. Using the resist mask MSN24B (Mini-Etsu, USA), the insulating layer 11 was formed using the CVD method (Watkins Johnson CVD furnace, USA), and the SiO ₂ film was heated to a thickness of 1000 Å at 450°C.
It was formed by vapor deposition. A yellow-colored Teflon filter (manufactured by Sumitomo Electric) was used as the counter electrode hiding layer. Otherwise, a negative type ECD with yellow letters on a blue background was completed in the same manner as in Example 1. These 7 segments
When turning ECD on WO ₃ membrane - IV・500msec,
When turning off -2.3V, 1 second, memory time
Aging was carried out at room temperature for one year under conditions of 62.5 seconds (short circuit between each electrode, which was ON as in Example 1), but no difference in optical density was observed between the background layer and the driving layer.

<Effects of the present invention> As described above, the present invention enables the mass production of ECDs with good display quality, and also enables the display of not only blue on a white background but also various colors on a blue background. The effect is great.

In order to prevent the background layer from fading, it is necessary to input a refresh signal at appropriate intervals.

[Brief explanation of the drawing]

Figure 1 is an exploded bird's-eye view of a conventional ECD cell, Figure 2 is a sectional view of A and B in Figure 1, Figure 3 is a,
b is a partial cross-sectional view used to explain the drawbacks of the conventional ECD, FIG. 4 is a bird's-eye view of the display electrode according to the present invention, FIG. 5 is a cross-sectional view of FIG. 4, and FIG. 6 is the present invention. FIG. 3 is an explanatory diagram of a process for manufacturing a display electrode structure according to the present invention. 11...Glass substrate, 12...EC layer, 13...
... Display electrode, 14 ... Background electrode, 15 ... Insulating layer.

Claims (1)

[Claims] 1. A first transparent electrode layer for coloring and decoloring segments formed on a transparent substrate in a pattern corresponding to display segments, and on the lead-out portion of the first transparent electrode layer and on the surface of the transparent substrate other than the segment. a transparent insulating layer deposited on the transparent insulating layer, a second transparent electrode layer for background tinting and decoloring formed on the transparent insulating layer, and an electrochromic electrode layer superimposed on these and deposited over substantially the entire area of the display area. The electrochromic material layer is characterized by an electrode structure capable of individually controlling coloring and decoloring of the segments of the display section and the background based on changes in coloring and decoloring of the electrochromic material. Electrochromic display device.