JP4011795B2 - Double-sided display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention generally relates to a double-sided display device that displays information on both front and back sides by applying a voltage.
[0002]
[Prior art]
Recently, the proposal and development of a paper-like display that has a function of electrically writing information but does not require maintenance power and can be easily carried like paper has been energized. This paper-like display is expected to replace paper media such as newspapers, magazines, and books that are the mainstream of current information supply in the future, and is expected to be a product form that will support ultra-lightweight homepage browsers. ing.
[0003]
By the way, this paper-like display has at least the same performance as a conventional paper medium, that is,
(1) It must be thin, lightweight and portable like a paper medium.
(2) Similar to paper media, it must have memory and no maintenance power is required.
(3) It must be inexpensive as with paper media.
Is required.
[0004]
Since books using paper media are configured by closing a plurality of paper media (as in a conventional display device, information is sequentially displayed while scrolling one display screen after another. Other information can be easily obtained in a short time by turning the page (without the need for such complicated work), and it can be read or read back while turning the page as needed. It has the qualities of facilitating understanding of the contents and facilitating the idea. In order to utilize this characteristic even in a paper-like display, it is desirable to use a plurality of paper-like displays as a book (hereinafter referred to as “electronic book”). In this case, a large amount of information downloaded in advance is displayed on each paper-like display. The above performances (1) to (3) are also important for realizing such an electronic book by a paper-like display.
[0005]
There are various proposals for such paper-like displays.
* Microcapsule type electrophoretic display (NATURE, Vol 394 [16], p253-255, 1998),
* Micro ball rotation type display (Proc. Of the SID, Vol118, 3/4, p289-293, 1977),
* Cholesteric liquid crystal display (J. of SID, Vol5 [3], p269-274, 1997),
There is something about.
[0006]
By the way, when a display medium having no clear threshold characteristic is used for the paper-like display, it is desirable that the drive is performed by an active matrix system. This active matrix method is a driving method which is currently mainstream in a liquid crystal display such as a notebook personal computer, and a semiconductor switching element such as a TFT or MIM is provided for each pixel and applied to each pixel. This is a drive system in which the switching voltage is controlled by these switching elements, and has an advantage that crosstalk, which is a problem in simple matrix drive, can be eliminated. As for the method of forming such a switching element, the switching element is formed using an organic semiconductor material that can be used for an inexpensive printing method without using an inorganic semiconductor material such as amorphous silicon or polysilicon, which increases the manufacturing cost. What
* NATURE, Vol 394 [16], p253-255, 1998,
* J. in Proc. Materials Research Soc. B8.2, 1998,
* SCEINCE, Vol 278 [17], p383-384, 1997
Etc. are proposed.
[0007]
There is also a proposal for a double-sided display device that displays information on both sides instead of only on one side of the display.
* Two liquid crystal panels bonded together (Japanese Patent Laid-Open No. 02-265923),
* In addition to an electrophoretic display device (Japanese Patent Laid-Open No. 01-126630) that has an intermediate electrode and displays the same as the front and back, as a proposal for a paper-like display,
* Polymer-dispersed liquid crystal display device (Japanese Patent Laid-Open No. 05-061024) configured to perform independent display on both surfaces of the intermediate support substrate,
There is.
[0008]
FIG. 9 is a sectional view showing an example of a conventional structure of a paper-like display disclosed in Japanese Patent Laid-Open No. 05-061024. This paper-like display D ₆ Comprises three substrates 1, 2 and 3, which are sequentially arranged in a state where a predetermined gap is opened substantially in parallel. Further, display electrodes 4 or 5 and switching elements 6 or 7 are formed on the respective surfaces of the middle substrate 2 (hereinafter referred to as “intermediate substrate 2”), and the display electrodes 4 and switching are formed on the respective surfaces. The element 6 and the display electrode 5 and the switching element 7 are electrically connected. Furthermore, electrodes 20 and 21 are also formed on the upper substrate 1 and the lower substrate 3, respectively. A control system (not shown) is disposed on both surfaces of the intermediate substrate 2, and by applying a voltage to the display electrodes 4 and 5 via the switching elements 6 and 7, separate information is provided on both the front and back surfaces. It can be displayed.
[0009]
Paper-like display D having the structure shown in FIG. ₆ Then, since the intermediate substrate 2 can be shared, the thickness and weight can be reduced to ½ to ¾ compared with the case where the same amount of information is displayed on two paper-like displays. Further, when such a paper-like display is used as an electronic book, there is an advantage that a double-sized screen can be viewed at a time.
[0010]
[Problems to be solved by the invention]
By the way, the paper-like display D mentioned above ₆ Then, since the switching elements 6 and 7 are formed on two surfaces (that is, both surfaces of the intermediate substrate 2), it is necessary to carry out the process of forming the switching elements twice, and the manufacturing cost increases accordingly. There was a problem that. In addition, the switching element 6 or 7 on either surface is formed in a state where the switching element 7 or 6 is already formed on the other surface, and the already formed switching element is subjected to process damage ( There was a risk of being affected by heat.
[0011]
Further, since the control system is provided independently on both sides of the intermediate substrate 2, there is a problem that the cost increases accordingly.
[0012]
Therefore, an object of the present invention is to provide a low-cost double-sided display device.
[0013]
[Means for Solving the Problems]
The present invention includes at least one substrate, first and second display media respectively disposed on the front and back surfaces of the one substrate, and a first substrate disposed on the one substrate along the first display medium. One display electrode, a first switching element electrically connected to the first display electrode, a second display electrode disposed on the one substrate along the second display medium, and the second A second switching element electrically connected to the display electrode; A first charge storage capacitor connected to the first display electrode; a second charge storage capacitor connected to the second display electrode; And applying the appropriate voltage to the first display electrode via the first switching element and applying the appropriate voltage to the second display electrode via the second switching element. In a double-sided display device that drives a display medium and the second display medium to perform double-sided display,
The first switching element and the second switching element are: On the same substrate surface as the first display electrode Arranged adjacent to each other,
The first charge storage capacitor and the second charge storage capacitor are disposed on the same substrate surface as the second display electrode, and the first charge storage capacitor includes a region where the first and second switching elements are formed. The second charge storage capacitor is formed under the second display electrode, and a part of the second display electrode is directly formed as an electrode of the second charge storage capacitor. It is characterized by that.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIG. 1, FIG. 2, FIG.
[0015]
A double-sided display device according to the present invention is shown in FIG. ₁ As shown in FIG. 3, at least one substrate 2, a first display medium (see upper reference numerals 22 and 23 shown in FIG. 3) and a second display medium (see FIG. 3) arranged on the front and back of the one substrate 2, respectively. Lower reference numerals 22, 23), a first display electrode 4 disposed on the one substrate along the first display medium, and the first display electrode 4 being electrically connected. A first switching element 6; a second display electrode 5 disposed on the one substrate along the second display medium; and a second switching element 7 electrically connected to the second display electrode 5. The first switching element 6 and the second switching element 7 are disposed adjacent to each other on the same side with respect to the one substrate 2 (details will be described later). And this double-sided display device D ₁ Applies the voltage to the first display electrode 4 through the first switching element 6 and applies the voltage to the second display electrode 5 through the second switching element 7. The display medium and the second display medium are each driven to perform double-sided display.
[0016]
In addition, as a display medium mentioned above,
* Microcapsule type electrophoretic display (NATURE, Vol 394 [16], p253-255, 1998),
* Micro ball rotation type display (Proc. Of the SID, Vol118, 3/4, p289-293, 1977),
* Cholesteric liquid crystal display (J. of SID, Vol5 [3], p269-274, 1997),
* Horizontal movement type electrophoretic display (Japanese Patent Laid-Open No. 49-024695),
Etc.
[0017]
Further, the first switching element 6 and the second switching element 7 are on the same side with respect to the one substrate 2 as described above (that is, on the upper side or lower side in the drawing with reference to the one substrate 2). As long as they are adjacent to each other (that is, adjacent to each other in the surface direction of the substrate). Specifically, the first switching element 6 and the second switching element 7 may be formed on the same surface of any substrate,
* As shown in FIG. 1, even if formed on the upper surface (one surface) of the one substrate 2,
* Even if it is formed on the lower surface of the one substrate 2 shown in the figure,
* As shown in FIG. 2, a pair of substrates 1, 3 are arranged so as to sandwich the one substrate 2, and even if formed on either surface of the pair of substrates 1, 3,
good.
[0018]
Here, the first display electrode 4, the first switching element 6 and the second switching element 7 are all formed on one surface of the one substrate 2 as shown in FIG. The electrode 5 may be formed on the other surface of the one substrate 2, and in that case, a through hole 2 a is formed in the one substrate 2 and a connection electrode 8 is disposed in the through hole 2 a, The electrical connection between the second switching element 7 and the second display electrode 5 is preferably performed through the connecting electrode 8. Similarly, the second display electrode 5, the first switching element 6, and the second switching element 7 are all formed on the other surface of the one substrate 2, and the first display electrode 4 is formed on the one substrate. 2 may be formed on one surface of the substrate 2, in which case the through hole 2 a is formed in the one substrate 2 and the connection electrode 8 is disposed in the through hole 2 a, and the first switching element 6 and the The electrical connection with the first display electrode 4 is preferably performed through the connecting electrode 8.
[0019]
The display electrodes 4 and 5 need only be disposed along the first display medium and the second display medium, and are not necessarily formed on the one substrate 2. For example, as indicated by reference numerals 1 and 3 in the figure, other substrates may be arranged and arranged on the surfaces of those substrates 1 and 3.
[0020]
On the other hand, as shown in detail in FIG. 4, a scanning electrode control circuit (not shown) is electrically connected to the first switching element 6 and the second switching element 7 through a common scanning electrode 9. A voltage may be applied as appropriate. One scanning electrode 9 may be connected only to the first switching element 6 or only to the second switching element 7 (not shown), but as shown in FIG. Some first switching elements 6 and second switching elements 7 (that is, some switching elements of the plurality of first switching elements 6 and some switching elements of the plurality of second switching elements 7) ) May be connected.
[0021]
4A, the first signal electrode 10 electrically connected to the first switching element 6 and the second signal electrode 10 electrically connected to the second switching element 7 are used. A signal electrode 11 may be provided, and a common signal electrode control circuit (not shown) may be connected to the first and second signal electrodes 10 and 11 to apply a voltage as appropriate.
[0022]
The scanning electrode 9, the first signal electrode 10, and the second signal electrode 11 are formed on a common surface in FIG. 4, but needless to say, the scanning electrode 9, the first signal electrode 10, and the second signal electrode 11 may be formed on different surfaces. In addition, these electrodes 9, 10, and 11 are formed on the surface on which the first switching element 6 and the second switching element 7 are formed in FIG. 4, but needless to say, this is not necessary. Furthermore, these electrodes 9, 10, 11
* It may be formed on the upper surface of the one substrate 2 in the figure,
* It may be formed on the lower surface of the one substrate 2 in the figure,
* It may be formed on the surface of another substrate 3,
* Furthermore, it is formed on the surface of another substrate 1,
You may do it.
[0023]
As the substrates 1, 2, and 3, a glass substrate or a flexible polymer substrate may be used.
[0024]
As the first and second switching elements 6 and 7, a thin film transistor element such as a TFT, an MIM type switching element that exhibits nonlinear diode characteristics, or the like can be used. In addition, the research report about the technology to form the switching element on the surface of the polymer substrate
* "Appl. Phys. Lett., Vol 70, No. 3, p342-344, 1997",
* "SCEIENCE, Vol 278 [17], p383-384, 1997",
* "NATURE, Vol 394 [16], p253-255, 1998",
* “J. in Proc. Materials Research Soc. B8.2, 1998”
It is made in,
* A method of forming switching elements 6 and 7 made of an inorganic material such as poly-Si on a polymer substrate at a low temperature by a laser annealing method,
* A method of forming a switching element 6, 7 on a polymer substrate by forming a polymer material such as polyimide or polyaniline by a printing method,
By using this, a flexible polymer substrate can be used as the substrate, and a flexible double-sided display device can be realized.
[0025]
In the double-sided display device according to the present embodiment, as shown in FIG. 8, the first charge storage capacitor 40 connected to the first display electrode 4 and the second charge storage connected to the second display electrode 5. When the capacitor 41 is disposed, the charge storage capacitors 40 and 41 are preferably formed on the same surface, and at least one of the charge storage capacitors 40 and 41 is formed in the through hole. It is preferable that the display electrode and the switching element are electrically connected by a connection electrode. The charge storage capacitors 40 and 41 are preferably formed on a surface different from the surface on which the first and second switching elements 6 and 7 are formed. Furthermore, these charge storage capacitors 40 and 41 are preferably formed so as to overlap the region where the first and second switching elements 6 and 7 are formed.
[0026]
In the above description, a cell comprising an intermediate support substrate and two counter substrates arranged opposite to each other has been described. However, the present invention is not necessarily limited to a configuration using three substrates. I don't mean. As an example, a switching element for both sides is arranged on either side of a single support substrate, and display electrodes are arranged on both front and back sides, and a microcapsule type electrophoretic display element, polymer dispersion type It is conceivable that a display medium layer made of a polymer sheet such as a liquid crystal element or a solid laminated thin film such as an organic EL is formed, and a transparent electrode film for driving and a protective film are sequentially formed thereon. As another example, in the above-mentioned horizontal movement type electrophoretic display device (Japanese Patent Laid-Open No. 49-024695), as a means for sealing the electrophoretic liquid, the counter substrate is not bonded through a spacer, A configuration may be considered in which a resin cavity such as silicon rubber in which partition walls between pixels are integrated is formed by using a replica method or the like.
[0027]
Next, the effect of this embodiment will be described.
[0028]
According to this embodiment, since the process of forming the first switching element 6 and the second switching element 7 is only required once, the manufacturing cost can be reduced as compared with the case where the process is performed twice or more. .
[0029]
In addition, according to the present embodiment, since the two types of switching elements 6 and 7 are formed at the same time, the conventional process damage can be avoided.
[0030]
Further, when the scanning electrode 9 is connected in common to several first switching elements 6 and second switching elements 7, the same scanning electrode control is applied to the first switching elements 6 and the second switching elements 7. A circuit can be used. As a result, as compared with the case where the first switching element 6 and the second switching element 7 are provided with separate scanning electrode control circuits, only one control circuit is required, and the cost can be reduced accordingly.
[0031]
On the other hand, when the charge storage capacitors 40 and 41 are formed on the same surface as described above, they can be manufactured in one process, and the manufacturing cost can be reduced. Further, when these charge storage capacitors 40 and 41 are formed so as to overlap the region where the first and second switching elements 6 and 7 are formed, the area efficiency and the aperture ratio are improved.
[0032]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples.
[0033]
Example 1
In this embodiment, a double-sided display type (upper and lower electrode type electrophoretic display element) D shown in FIGS. _Three It was created.
[0034]
That is, in this embodiment, as shown in FIG. 4A, the first display electrode 4, the front surface TFT (first switching element) 6, the back surface TFT (second switching element) 7, the scanning electrode 9, Both the first signal electrode 10 and the second signal electrode 11 were formed on one surface (upper surface) of the intermediate substrate (one substrate) 2. Among these, the first display electrode 4 is disposed for each pixel, and the front surface TFT 6 and the back surface TFT 7 are disposed one by one near each first display electrode 4 (portion other than the pixel). Further, the scanning electrodes 9 are arranged in a number corresponding to the pixel columns in the vertical direction shown in FIG. 4A so as to pass between the pixels, and the first signal electrode 10 and the second signal electrode 11 are the pixels. The number of pixels corresponding to twice the number of pixel rows is arranged in the horizontal direction shown in FIG. Further, the second display electrode 5 is formed for each pixel on the opposite surface (lower surface) of the intermediate substrate 2 as shown in FIGS.
[0035]
Further, a through hole 2a is formed in the vicinity of each pixel in the intermediate substrate 2, and a connecting electrode 8 is disposed in the through hole 2a. The diameter of the connection electrode 8 was 20 μm, and the connection electrode pad was a circular pad having a diameter of 40 μm that was slightly larger than the connection electrode 8.
[0036]
Each surface TFT 6 has its drain electrode electrically connected to the first display electrode 4, its source electrode electrically connected to the first signal electrode 10, and its gate electrode electrically connected to the scanning electrode 9. did. Each back surface TFT 7 has a drain electrode electrically connected to the second display electrode 5 through each connection electrode 8, a source electrode connected to the second signal electrode 11, and a gate electrode connected to the scanning electrode 9. did.
[0037]
A first common electrode 20 and a second common electrode 21 were formed on the surfaces of the upper substrate 1 and the lower substrate 3 so as to face the display electrodes 4 and 5, respectively. During driving, the common electrodes 20 and 21 were held at the reference potential.
[0038]
Further, between the upper substrate 1 and the intermediate substrate 2 and between the intermediate substrate 2 and the lower substrate 3, a colored liquid (display medium) 22 and charged colored electrophoretic fine particles (display medium) 23 are provided. These substrate gaps were sealed with a sealing member 24.
[0039]
In this embodiment, for convenience of explanation, the number of pixels is m × n, the number of scanning electrodes 9 is m, the number of first signal electrodes 10 is n, and the number of second signal electrodes 11 is n. To do.
[0040]
A transparent glass substrate is used for the upper substrate 1 and the lower substrate 3, and a TiO 2 is used for the intermediate substrate 2. ₂ A white glass in which was dispersed was used.
[0041]
The colored migrating fine particles 23 include white TiO having an average particle diameter of 5 μm. ₂ As the colored liquid 22, silicon oil in which a blue dye is dispersed is used.
[0042]
Next, double-sided display D _Three The manufacturing method will be described.
[0043]
Double-sided display D _Three First, a resist film is formed on both the upper and lower surfaces of the intermediate substrate 2, and portions where the first display electrode 4, the common scanning electrode 9, and the electrode pad of the connection electrode 8 are formed on the resist film on the upper surface side. Only a portion of the resist film on the lower surface side was subjected to pattern exposure to form a latent image by pattern exposure.
[0044]
Next, the resist films on both sides were developed, and the exposed portion was removed to form a negative image.
[0045]
Thereafter, a through hole 2a having a diameter of 20 μm was formed in the portion of the intermediate substrate 2 where the electrode pad is to be formed using a YAG laser.
[0046]
Further, Al films were formed on the upper and lower surfaces of the intermediate substrate 2 by a sputtering method. As a result, an Al film was formed on the portion from which the resist film was removed (the portion where each display electrode 4 and the like are formed and the inner surface of the through hole 2a).
[0047]
Next, a resin paste (conductive paste in which metal fine particles are dispersed) is applied to the through hole 2a by printing, and the applied resin paste is filled into the through hole with a blade or the like. The resin paste was removed. The resin paste filled in the through holes in this way was cured by heating. In this embodiment, a conductive paste in which metal fine particles are dispersed is used as the resin paste. However, a conductive paste in which carbon fine particles are dispersed may be used, or an insulating paste may be used. In this embodiment, the resin paste is applied by printing. However, the resin paste may be injected into the through hole by a nozzle, or the through hole may be filled with an electrode material by a metal plating method. .
[0048]
Thereafter, the resist film remaining on the intermediate substrate 2 was lifted off together with the Al film, and the first display electrode 4, the common scanning electrode 9, the connection electrode 8, the electrode pad, the second display electrode 5, and the wiring electrode were formed.
[0049]
Next, the surface of the common scanning electrode 9 where the TFTs 6 and 7 and the signal electrodes 10 and 11 intersect with each other is subjected to anodizing treatment to obtain Al. ₂ O _Three Formed.
[0050]
Then, using sputtering method Ta ₂ O _Five An insulating layer (not shown) made of was formed. In the present embodiment, the sputtering method is used. However, of course, the present invention is not limited to this, and other methods (for example, plasma CVD method) may be used. The insulating layer is made of SiO. ₂ Or SiN _X May be formed.
[0051]
Next, a-Si and an etching protective film SiN are formed by plasma CVD. _X Were successively laminated to form an etching protective film pattern. Then n ⁺ An a-Si ohmic layer was formed to form an a-Si island. Further, Cr was formed by sputtering and patterned to form the drain electrode, the source electrode, the first signal electrode 10 and the second signal electrode 11. After that, SiN as a passivation film _X A film was formed over the entire substrate.
[0052]
On the other hand, an ITO (indium tin oxide) thin film was formed on the surface of the upper substrate 1 by a sputtering method, and this was patterned to form a common electrode 20. Further, the common electrode 21 was formed on the lower substrate 3 by the same method.
[0053]
Next, these three substrates 1, 2, 3 were bonded at an interval of 50 μm with a spacer (not shown) interposed therebetween, and colored migrating fine particles 23 and colored liquid 22 were injected into the gap between the substrates. The substrate gap was sealed with a sealing member 24.
[0054]
Next, double-sided display D _Three The driving method will be described.
[0055]
The image information displayed on the front side and the image information displayed on the back side are sent to an image information processing circuit (not shown), and are divided into m × n pieces of pixel information.
[0056]
Corresponding to the arrangement of the first signal electrode 10 and the second signal electrode 11, signal information composed of 2n pieces of pixel information in which the front-side pixel information and the back-side pixel information are alternately arranged is each scanning electrode 9. And stored in a frame memory (not shown).
[0057]
In this state, a selection signal pulse voltage is applied to the first common scan electrode 9 from the scan electrode control circuit via a timing circuit (not shown), and the remaining (m−1) common scan electrodes 9 are applied. A non-selection signal pulse voltage is applied. As a result, the TFTs 6 and 7 along the selected common scanning electrode 9 are all turned on, and the TFTs 6 and 7 along the other common scanning electrode 9 are all turned off.
[0058]
Then, the signal information corresponding to the common scanning electrode 9 in the first column is sent from the frame memory to the signal electrode control circuit so as to synchronize with the selection period, and is sent to all the first signal electrodes 10 and the second signal electrodes 11. In contrast, pixel information is sent. In the pixels along the common scanning electrode 9 in the first column, the migrating fine particles 23 move in accordance with the voltages applied to the display electrodes 4 and 5 and the common electrodes 20 and 21, and display is performed.
[0059]
By performing such driving also on the other common scanning electrodes 9, double-sided display is possible.
[0060]
Next, the effect of the present embodiment will be described.
[0061]
According to the present embodiment, since all the TFTs 6 and 7 can be manufactured in one process, the manufacturing cost can be reduced as compared with the case where the process is performed twice, and the conventional process damage can be avoided.
[0062]
Furthermore, according to the present embodiment, all TFTs 6 and 7 can be driven by one scanning electrode control circuit, and the cost can be reduced.
[0063]
(Example 2)
In the present embodiment, the double-sided display type display (micro ball rotating type display element) D shown in FIGS. _Four It was created.
[0064]
That is, the MIM elements 6 and 7 are used as the first and second switching elements, the upper electrode of the MIM element 6 is electrically connected to the first display electrode 4, and the upper electrode of the MIM element 7 is connected via the connection electrode 8. The second display electrode 5 was connected.
[0065]
In addition, a silicon rubber support (display medium) 30 having cavities is disposed in the gap between the substrates, and a two-color ball (display medium) 31 is movably disposed in each cavity. Further, between each cavity and the two-color ball 31, silicon oil was filled as a lubricating liquid in order to reduce friction.
[0066]
Other structures were the same as those in Example 1.
[0067]
Next, double-sided display D _Four The manufacturing method will be described.
[0068]
First, similarly to Example 1, resist films were formed on the upper and lower surfaces of the intermediate substrate (one substrate) 2 and pattern exposure was performed to form a latent image. Then, the resist films on both sides were developed to form a negative image and the through hole 2a.
[0069]
Thereafter, a tantalum film was formed on both the upper and lower surfaces of the intermediate substrate 2 by sputtering. The through-hole 2a was filled with a conductive paste by the same method as in Example 1.
[0070]
Next, a resist film is formed again on the upper surface of the intermediate substrate 2, and only a part of the surface of the common scanning electrode 9 (part where the switching elements 6 and 7 are to be formed later) is removed by patterning, and the part is anodized About 60 nm thick Ta ₂ O _X Formed. Next, a Cr thin film was formed by sputtering and patterned to form an MIM upper electrode. As a result, MIM type switching elements 6 and 7 were formed. Thereafter, a passivation film was formed in the same manner as in Example 1.
[0071]
Further, common electrodes 20 and 21 were formed on the upper substrate 1 and the lower substrate 3 by the same method as in Example 1.
[0072]
Next, N.I. K. A fine particle rotation type display element was formed by a method proposed by Sheridon et al. (Proc. Of the SID, Vol 118, 3/4, p289 to 293, 1977). That is, a silicon rubber paste in which two-color balls having an average particle size of 50 μm are dispersed is applied and cured to a thickness of 100 μm on the surface of the first common electrode 20 and the surface of the second common electrode 21, respectively, and immersed in silicon oil. I let you. The silicone rubber paste swells when immersed in silicone oil, and the two-color balls 31 and the silicone rubber 30 are peeled off to form minute gaps, and silicon oil is filled between these minute gaps. The Finally, these three substrates 1, 2 and 3 were bonded together, and the gap between the substrates was sealed with a sealing member 24.
[0073]
Display D according to this embodiment _Four Was driven by the same method as in Example 1, but each pixel was given a steep threshold characteristic reflecting the nonlinear bidirectional diode characteristics of the MIM elements 6 and 7, and a voltage higher than the threshold was applied. The MIM diode of the selected pixel in the first column is turned on with a low resistance, while the MIM diodes of the non-selected pixels in the first column and 2 to m columns to which a voltage equal to or lower than the threshold is applied maintain a high resistance off state. To do. In this way, the micro ball 31 of each pixel is rotated to an appropriate state reflecting image information without crosstalk, and a desired display state is realized. Thereafter, the common display electrodes 9 are sequentially selected in sequence, and the same display writing is simultaneously performed on both sides of each scan electrode 9 to complete image formation on both sides.
[0074]
According to this example, the same effect as in Example 1 was obtained.
[0075]
(Example 3)
In this embodiment, a double-sided display (nematic liquid crystal display element) D shown in FIGS. _Five It was created.
[0076]
That is, in this embodiment, as in the first embodiment, the first display electrode 4, the front surface TFT (first switching element) 6, the back surface TFT (second switching element) 7, the scanning electrode 9, and the first signal. Both the electrode 10 and the second signal electrode 11 are formed on the upper surface of the intermediate substrate (one substrate) 2, and the second display electrode 5 is formed on the lower surface of the intermediate substrate 2. However, unlike the first embodiment, in addition to the second display electrode 5, the first charge storage capacitor 40, the second charge storage capacitor 41, and the charge storage capacitor common electrode 42 are formed on the lower surface of the intermediate substrate 2. The second charge storage capacitor 41 is formed below the second display electrode, and a part of the second display electrode 5 directly functions as the storage capacitor upper electrode. Further, alignment films (not shown) were formed on the surfaces of the display electrodes 4 and 5 and the common electrodes 20 and 21, and each alignment film was rubbed. Further, a nematic liquid crystal (display medium) 43 is disposed in the substrate gap.
[0077]
Other configurations were the same as those in Example 1.
[0078]
Next, double-sided display D _Five The manufacturing method will be described.
[0079]
As in Example 1, first, resist films were formed on the upper and lower surfaces of the intermediate substrate 2, and pattern exposure was performed to form a latent image, which was then developed to remove the exposed portion. In the lower surface of the intermediate substrate 2, portions where the charge storage capacitors 40 and 41, the charge storage capacitor common electrode 42 and the like are formed are also removed. Next, the through hole 2a was formed by the same method as in Example 1.
[0080]
Further, similarly to Example 1, Al films were formed by sputtering on the upper and lower surfaces of the intermediate substrate 2, and the inside of the through hole 2a was filled with a resin paste.
[0081]
Thereafter, as in Example 1, the resist film remaining on the intermediate substrate 2 is lifted off together with the Al film, and the first display electrode 4, the common scanning electrode 9, the connection electrode 8, the electrode pad, the second display electrode 5, etc. Created.
[0082]
Next, SiN is formed on the lower surface of the intermediate substrate 2 as an intermediate insulating layer of the charge storage capacitor by using a photolithography method, a sputtering method, or a plasma CVD method. _X Then, a Cr thin film was formed and patterned as a wiring electrode to the upper electrode and the connection electrode pad.
[0083]
Thereafter, TFTs 6 and 7 were formed by the same method as in Example 1.
[0084]
On the other hand, common electrodes 20 and 21 are formed on the surfaces of the upper substrate 1 and the lower substrate 3 by the same method as in the first embodiment, and a polyimide alignment film (not shown) is formed on the surfaces of the common electrodes 20 and 21. Formed and rubbed.
[0085]
Then, these three substrates 1, 2 and 3 are bonded together with a spacer (not shown) at an interval of 10 μm, nematic liquid crystal 43 is injected into the substrate gap, and the substrate gap is sealed by the sealing member 24. did.
[0086]
Double-sided display D according to this embodiment _Five Were driven by the same method as in Example 1.
[0087]
Next, the effect of the present embodiment will be described.
[0088]
According to this example, the same effect as in Example 1 was obtained.
[0089]
In addition, according to the present embodiment, the addition of the charge storage capacitors 40 and 41 increases the time constant of the circuit composed of the liquid crystal 43 and the charge storage capacitors 40 and 41, so that the voltage applied to the display electrodes 4 and 5 is attenuated. As a result, high contrast display is possible.
[0090]
Furthermore, according to the present embodiment, since the charge storage capacitor 40 is arranged on the back side of the TFTs 6 and 7 so as to overlap the TFTs 6 and 7, the area utilization efficiency can be improved and a good aperture ratio can be obtained.
[0091]
【The invention's effect】
As described above, according to the present invention, since the process of forming the first switching element and the second switching element is only required once, the manufacturing cost can be reduced as compared with the case where the process is performed twice.
[0092]
In addition, according to the present invention, since the two types of switching elements are formed at the same time, the conventional process damage can be avoided.
[0093]
Further, when the scan electrode is commonly connected to several first switching elements and second switching elements, the same scan electrode control circuit may be used for the first switching element and the second switching element. it can. As a result, the cost can be reduced as compared with the case where the scan electrode control circuit is provided separately for the first switching element and the second switching element.
[0094]
Further, when at least a part of the first charge storage capacitor and the second charge storage capacitor are formed so as to overlap the region where the first and second switching elements are formed, the area efficiency and the aperture ratio are increased. Is improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of the structure of a double-sided display device according to the present invention.
FIG. 2 is a cross-sectional view showing an example of the structure of a double-sided display device according to the present invention.
FIG. 3 is a cross-sectional view showing an example of the structure of a double-sided display device according to the present invention.
FIG. 4 is a diagram showing an example of the structure of a double-sided display device according to the present invention.
FIG. 5 is a cross-sectional view showing an example of the structure of a double-sided display device according to the present invention.
FIG. 6 is a diagram showing an example of the structure of a double-sided display device according to the present invention.
FIG. 7 is a cross-sectional view showing an example of the structure of a double-sided display device according to the present invention.
FIG. 8 is a diagram showing an example of the structure of a double-sided display device according to the present invention.
FIG. 9 is a cross-sectional view showing an example of a conventional structure of a paper-like display.
[Explanation of symbols]
1 Upper board
2 Intermediate substrate (one substrate)
2a Through hole
3 Lower board
4 First display electrode
5 Second display electrode
6 TFT (first switching element)
7 TFT (second switching element)
8 Connecting electrodes
9 Scanning electrode
10 First signal electrode
11 Second signal electrode
22 Colored liquid (display medium)
23 Colored electrophoretic fine particles (display medium)
30 Silicone rubber support (display medium)
31 Two-color ball (display medium)
40 First charge storage capacitor
41 Second charge storage capacitor
43 Nematic liquid crystal (display medium)
D ₁ Double-sided display device
D ₂ Double-sided display device
D _Three Double-sided display device
D _Four Double-sided display device
D _Five Double-sided display device

Claims (4)

At least one substrate, a first display medium and a second display medium respectively disposed on the front and back of the one substrate, and a first display electrode disposed on the one substrate along the first display medium; A first switching element electrically connected to the first display electrode, a second display electrode disposed on the one substrate along the second display medium, and an electric current to the second display electrode. A second switching element connected to the first display electrode; a first charge storage capacitor connected to the first display electrode; and a second charge storage capacitor connected to the second display electrode ; and A voltage is appropriately applied to the first display electrode via the first switching element, and a voltage is appropriately applied to the second display electrode via the second switching element to thereby provide the first display medium and the second display. Double-sided display by driving each medium In double-side display device which performs,
The first switching element and the second switching element are disposed adjacent to each other on the same substrate surface as the first display electrode ;
The first charge storage capacitor and the second charge storage capacitor are disposed on the same substrate surface as the second display electrode, and the first charge storage capacitor includes a region where the first and second switching elements are formed. The double-sided storage capacitor is formed so as to overlap with each other, and the second charge storage capacitor is formed under the second display electrode, and a part of the second display electrode is directly formed as an electrode of the second charge storage capacitor. Display device. Forming a through hole in the one substrate and arranging a connecting electrode in the through hole; and
The electrical connection between the second display electrode and the second switching element is performed through the connection electrode.
The double-sided display device according to claim 1 . The first switching element and the second switching element are electrically connected to a common scan electrode;
Double-side display device according to claim 1 or 2, characterized in that. A first signal electrode electrically connected to the first switching element, and a second signal electrode electrically connected to the second switching element, and
A common signal electrode control circuit is connected to these first and second signal electrodes and a voltage is applied as appropriate.
The double-sided display device according to any one of claims 1 to 3 .

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