JP2007072108A - Display element and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display element and a display device that can be used as an electronic paper or the like, that is easily read and gentle for eyes. <P>SOLUTION: The display element comprises: a cell 6 segmenting a hollow part 5 sealed by a display screen member 2, a rear face member 3, and a side face member 4; a conductive liquid 7 and an insulating liquid 8 housed in the hollow part 5, immiscible with each other and having different refractive indices from each other; and an interface changing means to change a form of the interface 9 between the conductive liquid 7 and the insulating liquid 8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a display element and a display device, and more particularly to a display element having a liquid lens and a display device in which a plurality of the display elements are arranged.

Application of various methods such as liquid crystal, microcapsule, electronic powder fluid, chromism, and organic EL is being studied as a display method for electronic paper.
On the other hand, Patent Document 1 describes an electrowetting technique that changes the position and shape of a liquid microlens on an insulating layer by applying a voltage.

  Patent Document 2 and Non-Patent Documents 1 and 2 apply electrowetting and apply a voltage to a cell in which two types of liquids that do not mix with each other and have different refractive indices and electrical conductivity are encapsulated. A technique is disclosed in which the interface shape of these two liquids is changed and these two liquids function as a liquid lens (fluid lens) having a variable focal length.

Among these, Patent Document 2 describes that a large number of the above-described liquid lenses are arranged as lenticular elements, and an image behind the liquid lens is displayed in a three-dimensional or flat display.
JP 2003-177219 A JP 2005-517991 A “Philips' fluid lenses bring things into focus”, [online], June 24, 2004, Royal Philips Electronics, [search August 12, 2005], Internet <URL: http://www.research.philips. com / newscenter / archive / 2004 / fluidlenses.html> “Technical Information”, [online], Varioptic, [Search August 27, 2005], Internet <URL: http://www.varioptic.com/technology.php>

Conventional display devices such as electronic paper have problems such as difficulty in reading and fatigue of eyes.
An object of the present invention is to solve such problems in the prior art, and to provide a display device that can be used as electronic paper that is easy to read and is easy on the eyes, and a display element used in such a display device.

The display element of the present invention is
A cell in which a hollow portion sealed by a display surface member, a back member, and a side member is defined;
A conductive liquid and an insulating liquid that are contained in the hollow portion and do not mix with each other and have different refractive indexes, and
Interface changing means for changing the shape of the interface between the conductive liquid and the insulating liquid;
The display surface member is composed of a substantially transparent body,
A colored portion of a color different from that of the back member is disposed at a substantially central portion of the hollow portion side surface of the back member,
The interface changing means includes a first electrode disposed outside the hollow portion so as not to be in electrical contact with the conductive liquid, and the hollow portion so as to be in electrical contact with the conductive liquid. And a second electrode arranged so that at least a part thereof faces, a voltage applying means for the conductive liquid,
The inner surface of the side member is set so that a contact angle with the conductive liquid is larger than 90 ° when the voltage application means is not applied.

  Since the display device of the present invention is configured as described above, when an external voltage is applied to the conductive liquid, the interface shape of two liquids having different refractive indexes accommodated in the hollow portion changes. That is, the radius of curvature of the liquid lens (fluid lens) composed of the conductive liquid and the insulating liquid is changed by the application of voltage, and therefore, the focal position when observing the inside of the cell from the display surface member Changes.

  The closer the focal position is to the colored portion on the surface of the back member, the larger the colored portion is observed from the display surface member side. That is, the display element displays the color of the colored portion. On the other hand, the farther the focal position is from the colored portion of the display surface member, the smaller the colored portion from the display surface member side, and the surrounding back member surface is observed. That is, the display element displays the color of the back member.

  For example, if the back member is black and the colored portion is white, when the liquid lens is a convex lens, the closer the focal position is to the colored portion, the more the display element becomes white and the focal position is colored. The further away from the part, the more black the display element. On the other hand, when the liquid lens is a concave lens, the smaller the imaginary focal length is, the smaller the white colored portion is, so that the black color becomes deeper.

The display device of the present invention is characterized in that a plurality of the display elements are arranged.
For this reason, it is possible to display a desired image as the entire display element by independently controlling the voltage applied to each display element constituting the display device.

  In the display device, it is preferable that the display device includes the display element in which a color of the coloring portion is red, the display element in green, and the display element in blue. By arranging display elements having different colors in the colored portions and independently controlling the voltages applied thereto, an image of a desired color can be displayed as a whole display device. Further, the color of the back member in this case can be black or white, for example.

  Since the display device using the display element of the present invention is non-luminous display, it is easy to read, does not cause eye fatigue, and has a high response speed when switching the display, and thus can display a moving image.

  In addition, since the display element and the display device of the present invention can switch the display only by applying or not applying voltage, the display element and the display device consume almost no power, thereby contributing to power saving and resource saving.

Hereinafter, the display element and the display device of the present invention will be described in more detail.
FIG. 1 is a schematic cross-sectional view showing an embodiment of the display element of the present invention.
The display element 1 includes a cell 6 in which a hollow portion 5 sealed with a display surface member 2, a back member 3, and a side member 4 is defined, and is contained in the hollow portion 5 and does not mix with each other and is refracted. Conductive liquid 7 and insulating liquid 8 having different rates and interface changing means 10 for changing the shape of the interface 9 between the conductive liquid 7 and the insulating liquid 8 are provided.

In the display element shown in FIG. 1, the cell 6 is a cylindrical cell having a circular cross section parallel to the display surface member 2. The shape of the cell 6 is not limited to such a cylinder as will be described later, and may be an arbitrary shape such as a prism.

If the display surface member 2 which comprises the cell 6 is transparent, there will be no limitation in particular, As a material, transparent resins, such as glass and an acrylic resin, etc. are mentioned.
The display surface member 2 may be colored, but is preferably colorless.

  From the display surface member 2, through the conductive liquid 7 and the insulating liquid 8 functioning as a liquid lens, the back surface member 3 and the colored portion 11 provided at the center thereof are observed. When light refraction at the two-liquid interface 9 is large, not only the back member 3 but also the second electrode 13 and the side member 4 may be observed. In such a case, it is preferable that the color of the hollow part side surface of the 2nd electrode 13 and the side member 4 is the same as that of the hollow part side surface of the back member 3.

  The back member 3 is preferably opaque. If the back member 3 is opaque, light is transmitted from the outside of the cell through the back member 3, and the display element 1 of the present invention does not exhibit a color different from a desired color.

  The coloring part 11 provided in the substantially central part of the hollow part side surface of the back member 3 is not particularly limited, and may be a figure such as a circle or a point drawn by a paint, for example. The area of this figure (or point) is, for example, 1/50 to 1/4, preferably 1/20 to 1/10, of the area of the back member 4 in contact with the hollow portion 5. Moreover, you may form the coloring part 11 by installing the member of a desired color on the surface of the back member 3 instead of drawing a figure etc.

  The hollow portion 5 of the cell 6 contains a conductive liquid 7 and an insulating liquid 8 that function as a liquid lens. As the conductive liquid 7 and the insulating liquid 8, liquids having different refractive indexes and not mixed with each other and separated into two phases are selected.

As the conductive liquid 7, water, a mixed solution of water and alcohol, saline, an aqueous potassium nitrate solution, or the like can be used.
Silicone oil, hydrocarbon liquid, etc. can be used as the insulating liquid 8, and hydrocarbon liquid such as Isoper-G (manufactured by ExxonMobil), TSF451-10 (manufactured by Toshiba Silicone), etc. Fluorine-based inert liquids such as silicone oil PF-5052 (manufactured by 3M) can be used.

Since the conductive liquid 7 and the insulating liquid 8 have different refractive indexes, these liquids function as lenses (liquid lenses) depending on the interface shape.
The shape of the lens can be controlled by a combination of the conductive liquid 7 and the insulating liquid 8, an applied voltage, etc., and is not only a convex lens and a concave lens, but flat (the radius of curvature is infinite or minus infinity) or A lens close to a flat shape can also be formed.

The refractive index ratio between the two is preferably 1.05 or more, more preferably 1.1 or more.
As a combination of the conductive liquid 7 and the insulating liquid 8, a combination of an aqueous potassium nitrate solution and a silicone oil is preferable.

The interface changing unit 10 includes a voltage applying unit 14 including a first electrode 12 and a second electrode 13, and enables application of an external voltage to the conductive liquid 7.
The first electrode 12 is installed outside the hollow portion 5 so as not to be in electrical contact with the conductive liquid 7. In the embodiment shown in FIG. 1, the first electrode 12 is installed so as to surround the hollow portion 5 with an insulating material (insulating layer) 15 interposed therebetween. The electrode 12 may be disposed so as to face each other with the insulating material (insulating layer) 15 and the hollow portion 5 interposed therebetween.

Avoidance of electrical contact between the first electrode 12 and the conductive liquid 7 can be achieved, for example, as follows;
(1) The side member 4 is formed of an insulating material 15, and the first electrode 12 is embedded in the side member 4, or the first electrode 12 is disposed on the outer surface of the side member 4, or (2) the side surface The first electrode 12 is disposed on the inner surface of the member 4, and the insulating layer 15 is formed on the inner surface of the first electrode 12.

  The second electrode 13 is disposed so that at least a part thereof faces the hollow portion 5 so as to be in electrical contact with the conductive liquid 7. In the embodiment shown in FIG. 1, the second electrode 13 has a ring shape and is disposed on the back member 3 side so as to surround the hollow portion 5 and partly contact the conductive liquid 7. Yes.

  When the first electrode 12 and the second electrode 13 are both disposed so as to surround the hollow portion 5 as in the embodiment shown in FIG. 1, the shape of the interface 9 between the conductive liquid 7 and the insulating liquid 8. Is preferable in that it is particularly uniform.

The applied voltage is, for example, 30 to 5000V, preferably 300 to 700V.
As shown in FIG. 1A, the inner surface (side surface of the hollow portion 5) 16 of the side member 4 has a contact angle larger than 90 ° with the conductive liquid 7 when the voltage application means 14 is not applied. That is, the inner surface 16 of the side member 4 needs to have liquid repellency with respect to the conductive liquid 7. For example, if the conductive liquid 7 is water or an aqueous solution of a salt such as potassium nitrate, the inner surface 16 of the side member 4 needs to have water repellency.

In order to make the inner surface 16 of the side member 4 exhibit liquid repellency with respect to the conductive liquid 7, for example, (1) the side member 4 itself is formed of a liquid repellent material, or (2) the hollow portion of the side member 4 is used. Means such as forming a liquid repellent layer on the 5-side surface are effective.

  For example, if the conductive liquid 7 is water or an aqueous solution of a salt such as potassium nitrate, the inner surface 16 of the side member 4 is made of a water repellent (hydrophobic) material. This material preferably further has an insulating property, and examples of such a material include fluorine resins such as Teflon (registered trademark).

Next, an operation based on voltage application will be described.
In the embodiment shown in FIG. 1, the conductive liquid 7 is a liquid having a low refractive index (lower refractive index than the insulating liquid 8; the same applies hereinafter), and the insulating liquid 8 has a high refractive index (from the conductive liquid 7). Is a liquid with a high refractive index. Examples of such a combination of the conductive liquid 7 and the insulating liquid 8 include a combination of water (conductive liquid 7) and silicone oil (conductive liquid 8). Moreover, although the color of the back member 3 and the coloring part 11 can be selected arbitrarily, suppose here that the back member 3 is black and the coloring part 11 is white.

  As shown in FIG. 1A, when no voltage is applied, the contact angle of the conductive liquid 7 with respect to the inner surface 16 of the side member is larger than 90 °, so the interface 9 has a convex shape toward the display surface member 2. Become. When the conductive liquid 7 is water, the inner surface 16 of the side member can be a fluororesin such as Teflon (registered trademark).

Since the refractive index of the conductive liquid 7 is lower than that of the insulating liquid 8, when the back surface member 3 side is observed from the display surface member 2 side, as shown in FIG. Since the surface of the back member 3 is observed, and the white colored portion 11 is observed to be small, the display element 1 is black. 2A and 2B, the image of the surface of the back member 3 observed from the display surface member is represented by 3a, and the image of the colored portion 11 is represented by 11a.

  On the other hand, as shown in FIG. 1B, when a voltage is applied to the conductive liquid 7 by the voltage applying unit 14, the interface 9 moves in the direction of the display surface member 2 in the vicinity of the side member 4. Is convex in the direction of the back member 3. Then, since the refractive index of the conductive liquid 7 is lower than that of the insulating liquid 8, when the back surface member 3 side is observed from the display surface member 2 side, as shown in FIG. Is greatly observed, and the display element 1 exhibits white.

  If the shape of the cross section of the cell 6 parallel to the display surface member 2 is substantially circular, that is, if the shape of the cell 6 is a cylinder, a tubular material having a circular cross section can be used as the side member 4. It is preferable in that the display element can be manufactured relatively easily.

  Further, if the shape of the cross section of the cell 6 parallel to the display surface member 2 is substantially square, substantially rectangular or substantially regular hexagon, that is, the shape of the cell 6 is a prism having a substantially square, substantially rectangular or substantially regular hexagonal bottom surface. This is preferable in that a display device can be formed by arranging a plurality of display elements without gaps.

  3 has the same cell structure as the embodiment shown in FIGS. 1A and 1B, and uses a high refractive index liquid as the conductive liquid 7 and a low refractive index liquid as the insulating liquid 8. FIG. It is a schematic cross section which shows one Embodiment of the display element of this invention.

  As shown in FIG. 3A, when no voltage is applied, the contact angle of the conductive liquid 7 with respect to the inner surface 16 of the side member is larger than 90 °, so the interface 9 has a convex shape toward the display surface member 2. Become. When the back surface member 3 side is observed from the display surface member 2 side, as shown in FIG. 2B, a large white colored portion 11 is observed, and the display element 1 exhibits white.

  On the other hand, as shown in FIG. 3B, when a voltage is applied to the conductive liquid 7 by the voltage applying means 14, the interface 9 moves in the direction of the display surface member 2 in the vicinity of the side member 4. Is convex in the direction of the back member 3. When the back member 3 side is observed from the display surface member 2 side, the black back member 3 surface around the colored portion 11 is observed and the white colored portion 11 is observed small as shown in FIG. The display element 1 is black.

  4 includes the same cell structure as the embodiment shown in FIGS. 1A and 1B, and uses a high refractive index liquid as the conductive liquid 7 and a low refractive index liquid as the insulating liquid 8. It is a schematic cross section which shows one Embodiment of the display element of this invention when the 2 electrode 13 is arrange | positioned at the display surface member 2 side.

  As shown in FIG. 4A, when no voltage is applied, the contact angle of the conductive liquid 7 with respect to the inner surface 16 of the side member is larger than 90 °, so the interface 9 has a convex shape toward the back member 3. . When the back surface member 3 side is observed from the display surface member 2 side, as shown in FIG. 2B, a large white colored portion 11 is observed, and the display element 1 exhibits white.

  On the other hand, as shown in FIG. 4B, when a voltage is applied to the conductive liquid 7 by the voltage application means 14, the interface 9 moves toward the back member 3 in the vicinity of the side member 4. It becomes a convex shape in the surface member 3 direction. When the back member 3 side is observed from the display surface member 2 side, the black back member 3 surface around the colored portion 11 is observed and the white colored portion 11 is observed small as shown in FIG. The display element 1 is black.

  FIG. 5 includes the same cell structure as the embodiment shown in FIGS. 4A and 4B, and uses a low refractive index liquid as the conductive liquid 7 and a high refractive index liquid as the insulating liquid 8. It is a schematic cross section which shows one Embodiment of the display element of this invention when the 2 electrode 13 is arrange | positioned at the display surface member 2 side.

  As shown in FIG. 5A, when no voltage is applied, the contact angle of the conductive liquid 7 with respect to the inner surface 16 of the side member is larger than 90 °, so the interface 9 has a convex shape toward the back member 3. . When the back member 3 side is observed from the display surface member 2 side, the black back member 3 surface around the colored portion 11 is observed and the white colored portion 11 is observed small as shown in FIG. The display element 1 is black.

  On the other hand, as shown in FIG. 5B, when a voltage is applied to the conductive liquid 7 by the voltage applying means 14, the interface 9 moves in the direction of the back member 3 in the vicinity of the side member 4. It becomes a convex shape in the surface member 3 direction. When the back surface member 3 side is observed from the display surface member 2 side, as shown in FIG. 2B, a large white colored portion 11 is observed, and the display element 1 exhibits white.

FIG. 6 is a schematic diagram for explaining the relationship between the shape of the interface 9 of each display element 1 and the display image 18 in a display device in which a plurality of the display elements 1 shown in FIG. 3 are arranged. .
By controlling the voltage applied to each display element 1 independently, the shape of the interface 9 of each display element 1 is controlled, the color exhibited by each display element 1 is switched, and various images 18 are displayed as the entire display device. Can be displayed.

Conventionally known means can be applied as means for controlling the voltage applied to each display element 1.
FIG. 7 is a schematic diagram for explaining an example of an image 18 shown by a display device in which a number of display elements 1 of the present invention in which the cross-sectional shape of the cell 6 is a circle is arranged. If the back member 3 of the display element 1 is black and the colored portion 11 is white, an image 18 in which a figure “mouth” is drawn in white on a black background is displayed.

  FIG. 8 is a schematic diagram for explaining an example of an image 18 shown by a display device in which a number of display elements 1 of the present invention in which the cross-sectional shape of the cell 6 is a regular hexagon are arranged. If the back member 3 of the display element 1 is black and the colored portion 11 is white, an image 18 in which a figure “mouth” is drawn in white on a black background is displayed.

FIGS. 9-1 and 9-2 are schematic views showing an embodiment of the display element of the present invention.
The display element 1 includes a cell 6 whose section parallel to the display surface member 2 (see FIG. 9A) is rectangular. The two first electrodes 12 are arranged so as to face each other via the hollow portion 5, and the two second electrodes 13 are arranged so as to face each other via the hollow portion 5. Further, as the colored portion 11 on the surface of the back member 3, a rectangle (straight line) is drawn at the center of the back member so as to be parallel to the two first electrodes 12.

If the conductive liquid 7 and the insulating liquid 8 are appropriately selected and the applied voltage is controlled, the display as shown in FIGS. 10A and 10B is performed.
FIG. 11 is a schematic diagram for explaining an example of an image 18 shown by a display device in which a large number of rectangular display elements 1 shown in FIGS. 9-1 and 9-2 are arranged. If the back member 3 of the display element 1 is black and the colored portion 11 is white, an image 18 in which a figure “mouth” is drawn in white on a black background is displayed.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a following example.

Using an acrylic resin as the display surface member 2, a vinyl chloride resin colored in black as the back member 3, and a vinyl chloride resin colored in black as the side member 4, the inner diameter is 6 mm.
A cell having an outer diameter of 8 mm and a height (outer shape) of 15 mm was prepared. The inner surface of the side member 4 is coated with a paint containing a fluororesin in order to develop water repellency, and the colored portion 11 is formed by drawing a circle having a diameter of about 2.7 mm at the center of the back member 3 with a white paint. Formed.

Further, the nickel electrodes 12 and 13 were installed as shown in FIG. 1A, and voltage applying means was provided.
In this cell, about 0.20 ml of potassium nitrate aqueous solution (concentration: 1% by weight) is used as the conductive liquid 7, and silicone oil (TSF451-10 (manufactured by Toshiba Silicone)) is used as the insulating liquid 8.
About 0.22 ml, and a display element was produced.

  The display element and the display device of the present invention can be used as display means in electronic paper or the like.

FIG. 1 is a schematic cross-sectional view of a display element according to an embodiment of the present invention. FIG. 2 is a schematic diagram of an image displayed by the display element shown in FIG. FIG. 3 is a schematic cross-sectional view of a display device according to still another embodiment of the present invention. FIG. 4 is a schematic cross-sectional view of a display element according to still another embodiment of the present invention. FIG. 5 is a schematic cross-sectional view of a display device according to still another embodiment of the present invention. FIG. 6 is a schematic diagram for explaining the relationship between the interface shape of each display element and the display image in a display device in which a plurality of display elements of the present invention are arranged. FIG. 7 is a schematic diagram of an image shown by the display device of the present invention. FIG. 8 is a schematic diagram of an image shown by the display device of the present invention. FIG. 9-1 is a schematic view of a display element according to still another embodiment of the present invention. FIG. 9-2 is a schematic view of a display element according to still another embodiment of the present invention. FIG. 10 is a schematic diagram of an image displayed by the display element shown in FIGS. 9-1 and 9-2. FIG. 11 is a schematic diagram of an image shown by the display device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Display element 2 ... Display surface member 3 ... Back surface member 3a ... Image of the surface of the back member 3 observed from the display surface member 2 4 ... Side member 5 ... Hollow part 6. .. Cell 7... Conductive liquid 8. Insulating liquid 9... Interface 10 between conductive liquid 7 and insulating liquid 8... Interface changing means 11. Image 12 of colored portion 11 observed from surface member 2... First electrode 13... Second electrode 14... Voltage applying means 15.
16 ... Inner side (hollow part 5 side) surface 17 of side member 4 ... Incident light 18 ... Display image

Claims (3)

A cell in which a hollow portion sealed by a display surface member, a back member, and a side member is defined;
A conductive liquid and an insulating liquid that are contained in the hollow portion and do not mix with each other and have different refractive indexes, and
Interface changing means for changing the shape of the interface between the conductive liquid and the insulating liquid;
The display surface member is composed of a substantially transparent body,
A colored portion of a color different from that of the back member is disposed at a substantially central portion of the hollow portion side surface of the back member,
The interface changing means includes a first electrode disposed outside the hollow portion so as not to be in electrical contact with the conductive liquid, and the hollow portion so as to be in electrical contact with the conductive liquid. And a second electrode arranged so that at least a part thereof faces, a voltage applying means for the conductive liquid,
The display element according to claim 1, wherein an inner surface of the side member is set such that a contact angle with the conductive liquid is larger than 90 ° when the voltage applying unit is not applied.   A display device in which a plurality of display elements according to claim 1 are arranged.   3. The display device according to claim 2, wherein the display device includes the display element in which a color of the colored portion is red, the display element in green, and the display element in blue.

Images