HK1148078A - Display element and electric apparatus using the same - Google Patents

Description

Display element and electric device using the same

Technical Field

The present invention relates to a display element that displays information such as images and characters by moving a conductive liquid, and an electric device using the display element.

Background

In recent years, display elements that display information by utilizing a phenomenon in which a conductive liquid is moved by an external electric field, such as display elements of an electrowetting method, have been developed and put into practical use.

Specifically, the conventional display device as described above is provided with, for example, as described in japanese patent application laid-open No. 2004-252444: the first and second electrodes 1 and 2, the first and second substrates 1 and 2, and colored droplets of a conductive liquid colored in a predetermined color are sealed in a display space formed between the substrates. In these conventional display elements, the shape of the colored liquid droplet is changed by applying an electric field to the colored liquid droplet via the 1 st electrode and the 2 nd electrode, thereby changing the display color on the display surface side.

In the conventional display element, a 1 st electrode and a 2 nd electrode are arranged in parallel on a 1 st substrate in an electrically insulated state from the colored droplets, and a 3 rd electrode is arranged on a 2 nd substrate side so as to face the 1 st electrode and the 2 nd electrode. And proposes: a cover for shielding light is provided over the 1 st electrode, whereby the 1 st electrode and the 2 nd electrode are provided on the non-effective display region side and the effective display region side, respectively, and a voltage is applied so that a potential difference is generated between the 1 st electrode and the 3 rd electrode or between the 2 nd electrode and the 3 rd electrode. In this conventional display element, the colored droplets are moved at a higher speed on the 1 st electrode side or the 2 nd electrode side than in the case where the shape of the colored droplets is changed, and the display color on the display surface side can be changed at a higher speed.

Disclosure of Invention

Problems to be solved by the invention

However, the conventional display element has a problem that the structure is complicated and large when the matrix driving is performed.

Specifically, in the conventional display element, a voltage of a negative potential is generally applied to the 3 rd electrode and a voltage of a positive potential is generally applied to one of the 1 st electrode and the 2 nd electrode for each display unit (pixel). In the conventional display element, the colored liquid droplet (conductive liquid) is moved to the 1 st electrode (non-effective display region) side or the 2 nd electrode (effective display region) to which the positive potential is applied. Therefore, in the conventional display element, when the matrix driving is performed by applying the display element to a plurality of pixels, the 1 st electrode to the 3 rd electrode must be provided for each pixel, and the structure of the display element becomes complicated and large.

In addition, in the conventional display element, the 1 st to 3 rd electrodes are shared by a plurality of pixels, and the 3 rd electrode is configured to be capable of applying a voltage of a positive potential or a negative potential in units of pixels, thereby enabling matrix driving. However, in the case of this structure, other problems arise: the conductive liquid may be unstable and may change unnecessarily, thereby degrading the display quality of the display device.

In view of the above problems, an object of the present invention is to provide a display element having a good display quality and capable of preventing a complicated and large-sized structure even when matrix driving is performed, and an electric apparatus using the display element.

Means for solving the problems

In order to achieve the above object, a display element of the present invention includes:

a 1 st substrate provided on a display surface side, a 2 nd substrate provided on a non-display surface side of the 1 st substrate so as to form a predetermined display space with the 1 st substrate, an effective display region and a non-effective display region set in the display space, and a conductive liquid sealed in the display space and movable to the effective display region side or the non-effective display region side,

the display color on the display surface side can be changed by moving the conductive liquid,

the display element is characterized in that:

the disclosed device is provided with: a signal electrode provided inside the display space so as to be in contact with the conductive liquid;

a reference electrode provided on one of the 1 st substrate and the 2 nd substrate so as to be electrically insulated from the conductive liquid, the reference electrode being provided on one of the effective display region side and the non-effective display region side; and

a scanning electrode provided on one of the 1 st substrate and the 2 nd substrate so as to be electrically insulated from the conductive liquid and the reference electrode and provided on the other of the effective display region side and the non-effective display region side,

the signal electrode, the reference electrode, and the scan electrode are capable of applying a voltage within a predetermined voltage range between a 1 st voltage and a 2 nd voltage independently of each other,

a3 rd voltage that is a voltage between the 1 st voltage and the 2 nd voltage is applied to the reference electrode, and a 4 th voltage that is substantially the same as the 3 rd voltage is applied to the scan electrode.

In the display element having the above-described configuration, the signal electrode, the reference electrode, and the scan electrode can apply a voltage within a predetermined voltage range between the 1 st voltage and the 2 nd voltage independently of each other. Thus, unlike the conventional example, the structure can be prevented from being complicated and enlarged even when the matrix driving is performed. In addition, the 3 rd voltage is applied to the reference electrode and the 4 th voltage is applied to the scan electrode. Thus, even when the matrix driving is performed, unnecessary fluctuation of the conductive liquid can be suppressed, and a display element with good display quality in which deterioration of display quality due to fluctuation of the conductive liquid can be prevented can be configured.

The 4 th voltage substantially the same as the 3 rd voltage means a voltage having a predetermined voltage width with respect to the 3 rd voltage, and when a voltage within a predetermined voltage range between the 1 st voltage and the 2 nd voltage is applied to the signal electrode, and when the 3 rd voltage and the 4 th voltage are applied to the reference electrode and the scanning electrode, respectively, the conductive liquid is prevented from moving, and unnecessary variation in the current position of the conductive liquid can be suppressed.

In the display device, it is preferable that the plurality of signal electrodes are arranged in a predetermined arrangement direction, and the plurality of reference electrodes and the plurality of scanning electrodes are arranged so as to alternate with each other and intersect the plurality of signal electrodes, and the display device includes: a signal voltage applying unit which is connected to the plurality of signal electrodes and applies a signal voltage in a predetermined voltage range between the 1 st voltage and the 2 nd voltage to each of the plurality of signal electrodes based on information displayed on the display surface side; a reference voltage applying unit that is connected to the plurality of reference electrodes and applies one of a selection voltage that allows the conductive liquid to move inside the display space in accordance with the signal voltage and a non-selection voltage that prevents the conductive liquid from moving inside the display space to each of the plurality of reference electrodes; and a scanning voltage applying unit that is connected to the plurality of scanning electrodes and applies one of a selection voltage that allows the conductive liquid to move inside the display space in accordance with the signal voltage and a non-selection voltage that prevents the conductive liquid from moving inside the display space to each of the plurality of scanning electrodes.

In this case, a matrix-drive display element having excellent display quality can be easily configured.

Further, a plurality of pixel regions may be provided on the display surface side, each of the plurality of pixel regions may be provided in a unit of an intersection of the signal electrode and the scanning electrode, and the display space may be partitioned by a partition wall in each of the pixel regions.

In this case, the conductive liquid of each of the plurality of pixels on the display surface side is moved to change the display color on the display surface side in units of pixels.

In the display element, the plurality of pixel regions may be provided for each of a plurality of colors which can be displayed in full color on the display surface side.

In this case, color image display can be performed by appropriately moving the conductive liquid corresponding to each of the plurality of pixels.

In the display device, it is preferable that an insulating fluid immiscible with the conductive liquid is sealed in the display space so as to be movable in the display space.

In this case, the moving speed of the conductive liquid can be easily increased.

In the display device, a dielectric layer is preferably laminated on the surfaces of the reference electrode and the scanning electrode.

In this case, the dielectric layer can reliably increase the electric field applied to the conductive liquid, and the moving speed of the conductive liquid can be more easily increased.

In the display device, transparent sheets may be used as the 1 st substrate and the 2 nd substrate, and a backlight device may be provided on the rear surface side of the 2 nd substrate.

In this case, the display operation is performed using the illumination light from the backlight device, and even when the external light is insufficient, the display operation can be performed appropriately at night, or the like. In addition, a high-luminance display element having a large dimming range and capable of easily performing highly accurate gradation control can be easily configured.

In the display device, a transparent sheet may be used as the 1 st substrate, and a light reflecting portion may be provided on the 2 nd substrate.

In this case, the light reflecting portion reflects external light incident from the outside to perform a display operation, and thus a display element with low power consumption and reduced weight can be easily configured.

In the display device, a transparent sheet may be used as the 1 st substrate, a light reflecting portion and a transparent portion may be provided on the 2 nd substrate side in parallel, and a backlight device may be provided on the rear surfaces of the light reflecting portion and the transparent portion.

In this case, since the display operation is performed by the external light reflected by the light reflection unit and the illumination light from the backlight device, it is possible to easily configure a high-luminance display element which reduces power consumption of the backlight device, increases a light control range, and easily performs highly accurate gradation control.

In the display device, it is preferable that each of the 3 rd voltage and the 4 th voltage has a voltage value that is an intermediate value between the 1 st voltage and the 2 nd voltage.

In this case, the conductive liquid can be brought into a more stable state, and display quality can be reliably improved.

In the display device, the non-effective display region may be defined by a light-shielding film provided on one of the 1 st substrate and the 2 nd substrate, and the effective display region may be defined by an opening formed in the light-shielding film.

In this case, the effective display region and the ineffective display region can be accurately and reliably set in the display space.

Further, an electrical device according to the present invention is an electrical device including a display unit that displays information including characters and images, the electrical device including: the display unit employs any of the above display elements.

In the electric device having the above-described configuration, since the display element having a good display quality and a complicated and large-sized structure can be prevented even when the matrix driving is performed in the display portion, a high-performance electric device having a good display quality can be easily configured.

Effects of the invention

According to the present invention, a display element having a good display quality and capable of preventing a complicated and large-sized structure even when matrix driving is performed, and an electric device using the display element can be provided.

Drawings

Fig. 1 is a plan view illustrating a display element and an image display device according to embodiment 1 of the present invention.

Fig. 2 is an enlarged plan view showing an essential structure on the upper substrate side shown in fig. 1 in a state of being viewed from the display surface side.

Fig. 3 is an enlarged plan view showing an essential structure of the lower substrate side shown in fig. 1 in a state of being viewed from the non-display surface side.

Fig. 4 (a) and (b) are sectional views showing the essential structure of the display element shown in fig. 1 in the non-CF colored display and the CF colored display, respectively.

Fig. 5 is a diagram illustrating an operation example of the image display device.

Fig. 6 is a diagram illustrating a more specific operation example of the image display device, and (a) and (b) are diagrams illustrating an initial state and a state in a next stage of the initial state, respectively.

Fig. 7 is a diagram illustrating a more specific operation example of the image display device, and (a) and (b) are diagrams sequentially illustrating states at stages subsequent to the state shown in fig. 6 (b).

Fig. 8 is a timing chart showing the magnitude and the application time of the applied voltage in a more specific operation example of the image display device.

Fig. 9 is a diagram for explaining specific effects of the present embodiment, where (a) and (b) are schematic side views of the display element and plan views of an image region of the display element, respectively, and (c) and (d) are schematic side views of a comparative product and plan views of a pixel region of the comparative product, respectively.

Fig. 10 (a) and (b) are sectional views showing the essential structure of the display element according to embodiment 2 of the present invention in the non-CF colored display mode and the CF colored display mode, respectively.

Fig. 11 (a) and (b) are sectional views showing the essential structure of the display element according to embodiment 3 of the present invention in the non-CF colored display mode and the CF colored display mode, respectively.

Fig. 12 (a) and (b) are sectional views showing essential structures of a modification of the display element shown in fig. 1 in the non-CF colored display and the CF colored display, respectively.

Detailed Description

Preferred embodiments of a display element and an electric apparatus of the present invention are described below with reference to the drawings. In the following description, the case where the present invention is applied to an image display device including a display unit capable of displaying a color image display will be described as an example. The dimensions of the structural members in the drawings do not faithfully represent the actual dimensions of the structural members, the dimensional ratios of the structural members, and the like.

< embodiment 1 >

Fig. 1 is a plan view illustrating a display element and an image display device according to embodiment 1 of the present invention. The image display device 1 of the present embodiment shown in fig. 1 is provided with a display unit using the display element 10 of the present invention, and the display unit has a rectangular display surface. That is, the display element 10 includes an upper substrate 2 and a lower substrate 3 arranged to overlap each other in a direction perpendicular to the paper surface of fig. 1, and an effective display region of the display surface is formed by an overlapping portion of the upper substrate 2 and the lower substrate 3 (details will be described later).

In the display element 10, the plurality of signal electrodes 4 are arranged in stripes in the X direction with a predetermined interval therebetween. In addition, in the display element 10, a plurality of reference electrodes 5 and a plurality of scan electrodes 6 are alternately arranged in stripes in the Y direction. The plurality of signal electrodes 4, the plurality of reference electrodes 5, and the plurality of scanning electrodes 6 are provided so as to intersect with each other, and in the display element 10, each of the plurality of pixel regions is set in units of the intersection of the signal electrodes 4 and the scanning electrodes 6.

The plurality of signal electrodes 4, the plurality of reference electrodes 5, and the plurality of scanning electrodes 6 are capable of applying a voltage within a predetermined voltage range between a high voltage as a 1 st voltage and a low voltage as a 2 nd voltage, independently of each other (details will be described later).

As will be described in detail later, the display element 10 is configured such that each of the plurality of pixel regions is partitioned by a partition wall, and the plurality of pixel regions are provided corresponding to a plurality of colors which can be displayed in full color on the display surface side. In the display element 10, a conductive liquid described later is moved by electrowetting in a plurality of pixels (display cells) each arranged in a matrix, and a display color on the display surface side is changed.

Further, the plurality of signal electrodes 4, the plurality of reference electrodes 5, and the plurality of scanning electrodes 6 have one end portion drawn out to the outside of the effective display area of the display surface, and form terminal portions 4a, 5a, and 6 a.

The signal driver 7 is connected to the terminal portions 4a of the plurality of signal electrodes 4 by wires 7 a. The signal driver 7 constitutes a signal voltage applying section, and applies a signal voltage Vd corresponding to information to each of the plurality of signal electrodes 4 when the image display device 1 displays information including characters and images on the display surface.

The reference driver 8 is connected to the terminal portions 5a of the plurality of reference electrodes 5 by wires 8 a. The reference driver 8 constitutes a reference voltage applying section that applies a reference voltage Vr to each of the plurality of reference electrodes 5 when the image display device 1 displays information including characters and images on the display surface.

The scan driver 9 is connected to the terminal portions 6a of the plurality of scan electrodes 6 via wires 9 a. The scan driver 9 constitutes a scan voltage applying section, and applies a scan voltage Vs to each scan electrode 6 of the plurality of scan electrodes 6 when the image display device 1 displays information including characters and images on the display surface.

In the scan driver 9, one of a non-selection voltage for preventing the movement of the conductive liquid and a selection voltage for allowing the conductive liquid to move according to the signal voltage Vd is applied as a scan voltage Vs to each of the plurality of scan electrodes 6. The reference driver 8 operates with reference to the operation of the scan driver 9, and the reference driver 8 applies, as the reference voltage Vr, one of a non-selection voltage that prevents the conductive liquid from moving and a selection voltage that allows the conductive liquid to move in accordance with the signal voltage Vd to each of the plurality of reference electrodes 5.

In the image display device 1, the scan driver 9 sequentially applies a selection voltage to the scan electrodes 6 from the left side to the right side in fig. 1, for example, and the reference driver 8 sequentially applies a selection voltage to the scan electrodes 6 from the left side to the right side in fig. 1 in synchronization with the operation of the scan driver 9, thereby performing a scanning operation for each line (details will be described later).

The signal driver 7, the reference driver 8, and the scan driver 9 include a dc power supply or an ac power supply, and supply the corresponding signal voltage Vd, the reference voltage Vr, and the scan voltage Vs.

The reference driver 8 switches the polarity of the reference voltage Vr at predetermined time intervals (for example, 1 frame). The scan driver 9 switches the polarities of the scan voltages Vs in accordance with the switching of the polarity of the reference voltage Vr. Since the polarities of the reference voltage Vr and the scanning voltage Vs are switched at predetermined intervals in this way, it is possible to prevent localization of charges in the reference electrode 5 and the scanning electrode 6, as compared with a case where a voltage of the same polarity is always applied to the reference electrode 5 and the scanning electrode 6. Further, it is possible to prevent a display failure (afterimage phenomenon) due to localization of electric charges and a bad influence on reliability (reduction in lifetime).

Here, the pixel configuration of the element 10 is specifically and clearly shown with reference also to fig. 2 to 4.

Fig. 2 is an enlarged plan view showing an essential structure on the upper substrate side shown in fig. 1 when viewed from the display surface side. Fig. 3 is an enlarged plan view showing an essential structure of the lower substrate side shown in fig. 1 when viewed from the non-display surface side. Fig. 4 (a) and (b) are sectional views showing the essential structure of the display element shown in fig. 1 in the non-CF colored display and the CF colored display, respectively. In fig. 2 and 3, 12 pixels arranged at the upper left end of fig. 1 among the plurality of pixels provided on the display surface are illustrated to simplify the drawing.

In fig. 2 to 4, the display device 10 includes the upper substrate 2 as a 1 st substrate provided on the display surface side and the lower substrate 3 as a 2 nd substrate provided on the back surface side (non-display surface side) of the upper substrate 2. In the display device 10, the upper substrate 2 and the lower substrate 3 are arranged with a predetermined distance therebetween, and thereby a predetermined display space S is formed between the upper substrate 2 and the lower substrate 3. In the display space S, the conductive liquid 16 and the insulating oil 17 immiscible with the conductive liquid 16 are sealed in the display space S and are movable in the X direction (the left-right direction in fig. 4), and the conductive liquid 16 is movable to an effective display region P1 side or an ineffective display region P2 described later.

As the conductive liquid 16, for example, an aqueous solution containing water as a solvent and a predetermined electrolyte as a solute is used. Specifically, as the conductive liquid 16, for example, a 1mmol/L aqueous solution of potassium chloride (KCL) is used. In addition, as the conductive liquid 16, a solution colored black by a pigment, a dye, or the like is used.

Since the conductive liquid 16 is colored black, the conductive liquid 16 functions as a shutter for allowing or blocking light transmission in each pixel. That is, in each pixel of the display element 10, as will be described in detail later, the conductive liquid 16 slides inside the display space S toward the reference electrode 5 (toward the effective display region P1) or toward the scanning electrode 6 (toward the non-effective display region P2), and the display color is changed to either black or RGB.

Further, as the oil 17, for example, one or more nonpolar, colorless and transparent oils selected from side chain higher alcohols, side chain higher fatty acids, alkanes, silicone oils, and matching oils are used. The oil 17 moves inside the display space S along with the sliding movement of the conductive liquid 16.

The upper substrate 2 is made of a transparent glass material such as an alkali-free glass substrate or a transparent sheet such as a transparent synthetic resin such as an acrylic resin. Further, a color filter layer 11 and a water-repellent film 12 are formed in this order on the surface of the upper substrate 2 on the non-display surface side, and the signal electrode 4 is also formed on the water-repellent film 12.

As the lower substrate 3, a transparent sheet made of a transparent glass material such as an alkali-free glass substrate or a transparent synthetic resin such as an acrylic resin is used, as in the upper substrate 2. The reference electrode 5 and the scanning electrode 6 are provided on the surface of the lower substrate 3 on the display surface side, and a dielectric layer 13 is formed so as to cover the reference electrode 5 and the scanning electrode 6. On the surface of the dielectric layer 13 on the display surface side, ribs 14a and 14b are provided in parallel with the Y direction and the X direction, respectively. A waterproof film 15 is provided on the lower substrate 3 so as to cover the dielectric layer 13 and the ribs 14a and 14 b.

A backlight 18 for emitting white illumination light, for example, is integrally incorporated on the rear surface side (non-display surface side) of the lower substrate 3, thereby constituting a transmissive display element 10.

The Color Filter (Color Filter) layer 11 is provided with Color Filter portions 11R, 11G, and 11B of red (R), green (G), and blue (B) and a black matrix portion 11s as a light shielding film, and constitutes pixels of respective colors of RGB. That is, as shown in fig. 2, in the color filter layer 11, RGB color filter portions 11r, 11g, and 11b are provided in the X direction in this order, 4 color filter portions 11r, 11g, and 11b are provided in the Y direction, and 3 pixels, 4 pixels, and 12 pixels in total are provided in the X direction and the Y direction.

As shown in the example of fig. 2, in the display element 10, any of the color filter portions 11r, 11g, and 11b of RGB is provided in each pixel region P at a position corresponding to the pixel effective display region P1, and the black matrix portion 11s is provided at a position corresponding to the non-effective display region P2. That is, in the display element 10, a non-effective display region P2 (non-opening portion) is set in the display space S by the black matrix portion (light shielding film) 11S, and an effective display region P1 is set by the opening portion (i.e., any of the color filter portions 11r, 11g, and 11b) formed in the black matrix portion 11S.

In the display element 10, the areas of the color filter portions 11r, 11g, and 11b are selected to be the same as or slightly larger than the area of the effective display region P1. On the other hand, the area of the black matrix portion 11s is selected to be the same as or slightly smaller than the area of the non-effective display region P2. In fig. 2, in order to clarify the boundary between adjacent pixels, the boundary between the black matrix portions 11s corresponding to the adjacent pixels is indicated by a broken line, but in the actual color filter layer 11, the boundary between the black matrix portions 11s does not exist.

In the display element 10, the ribs 14a and 14b serving as the partition walls partition the display space S in units of the pixel region P. That is, as shown in the example of fig. 3, in the display element 10, the display space S of each pixel is partitioned by 2 ribs 14a facing each other and two ribs 14b facing each other. In the display element 10, the ribs 14a and 14b prevent the conductive liquid 16 from flowing into the display space S of the adjacent pixel region P. That is, for example, a photocurable resin is used for the ribs 14a and 14b, and the protruding heights of the ribs 14a and 14b from the dielectric layer 13 are determined so as to prevent the conductive liquid 16 from flowing into and out of adjacent pixels.

In addition to the above description, ribs constituting a frame shape may be provided on the lower substrate 3 in units of pixels, for example, instead of the ribs 14a and 14 b. Further, the top end portions of the frame-shaped ribs may be closely attached to the upper substrate 2 side so that the adjacent pixel regions P are hermetically separated from each other. When the tip of the rib is brought into close contact with the upper substrate 2, the signal electrode 4 may be provided inside the display space S by providing the signal electrode 4 so as to penetrate the rib.

The water-repellent films 12 and 15 are made of a transparent synthetic resin, and preferably a fluorine-based resin, for example, which becomes a hydrophilic layer with respect to the conductive liquid 16 when a voltage is applied. Thus, in the display element 10, the wettability (contact angle) of the conductive liquid 16 with respect to the respective surface sides of the upper substrate 2 and the lower substrate 3 on the display space S side can be changed greatly, and the moving speed of the conductive liquid 16 can be increased. The dielectric layer 13 is formed of a transparent dielectric film containing, for example, parylene, silicon nitride, hafnium oxide, zinc oxide, titanium dioxide, or aluminum oxide.

The reference electrode 5 and the scanning electrode 6 are made of indium oxide (ITO) and tin dioxide (SnO)₂) Or a transparent electrode material such as zinc oxide (AZO, GZO, or IZO). The reference electrodes 5 and the scanning electrodes 6 are formed in a band shape on the lower substrate 3 by a known film forming method such as a sputtering method.

The signal electrode 4 is a linear wiring arranged parallel to the X direction. The signal electrode 4 is provided on the water-repellent film 12, and passes through substantially the center portion of each pixel region P in the Y direction, and is inserted with the conductive liquid 16 so as to be in direct contact with the conductive liquid 16. This improves the response of the conductive liquid 16 during the display operation in the display element 10.

A transparent water-repellent film (not shown) made of, for example, a fluorine-based resin is laminated on the surface of the signal electrode 4, and the conductive liquid 16 is smoothly slid and moved. The waterproof film does not electrically insulate the signal electrode 4 from the conductive liquid 16, and does not inhibit improvement of the responsiveness of the conductive liquid 16.

In addition to the above description, the color filter layer 11, the signal electrode 4, and the water-repellent film 12 may be sequentially stacked on the surface of the upper substrate 2 on the non-display surface side.

In addition, since the signal electrode 4 is made of a material that is electrochemically inert to the conductive liquid 16, the signal electrode 4 is prevented from electrochemically reacting with the conductive liquid 16 as much as possible even when the signal voltage Vd (for example, 40V) is applied to the signal electrode 4. This prevents the signal electrode 4 from being electrolyzed, and improves the reliability and life of the display element 10.

Specifically, the signal electrode 4 is made of an electrode material containing at least one of gold, silver, copper, platinum, and palladium. The signal electrode 4 is formed by fixing a thin wire made of the metal material to the color filter layer 11, and placing an ink material such as a conductive paint containing a metal material on the color filter layer 11 by a screen printing method or the like.

The shape of the signal electrode 4 is determined by the transmittance of the reference electrode 5 provided below the effective display region P1 of the pixel. Specifically, in the signal electrode 4, the shape of the signal electrode is determined based on the transmittance of the reference electrode 5 of about 75% to 95% so that the occupied area of the signal electrode 4 in the effective display region P1 is 30% or less, preferably 10% or less, and more preferably 5% or less with respect to the area of the effective display region P1.

As shown in fig. 4a, in each pixel of the display element 10 having the above-described structure, when the conductive liquid 16 is held between the color filter portion 11r and the reference electrode 5, light from the backlight 18 is blocked by the conductive liquid 16, and black display (non-CF color display) is performed. On the other hand, as shown in fig. 4b, when the conductive liquid 16 is held between the black matrix portion 11s and the scanning electrodes 6, light from the backlight 18 is transmitted through the color filter portion 11r without being blocked by the conductive liquid 16, thereby performing red display (CF color display).

Here, the display operation of the image display device 1 according to the present embodiment configured as described above will be specifically described with reference to fig. 5 to 8.

First, a basic operation of the image display device 1 will be described with reference to fig. 5.

Fig. 5 is a diagram illustrating an operation example of the image display device.

In fig. 5, the reference driver 8 and the scan driver 9 sequentially apply the above-described selection voltages as the reference voltage Vr and the scan voltage Vs to the reference electrode 5 and the scan electrode 6, respectively, in a scan direction defined from, for example, the left side to the right side of the same figure. Specifically, the reference driver 8 and the scan driver 9 sequentially apply a high voltage (1 st voltage) and a low voltage (2 nd voltage) as selection voltages to the reference electrodes 5 and the scan electrodes 6, respectively, to perform a scan operation as selection lines. In the selection line, the signal driver 7 applies a high voltage or a low voltage as the signal voltage Vd to the corresponding signal electrode 4 in accordance with an external image input signal. Thus, in each pixel of the selection line, the conductive liquid 16 moves to the effective display region P1 side or the ineffective display region P2, and the display color on the display surface side is changed.

On the other hand, the reference driver 8 and the scan driver 9 apply the above-described non-selection voltages as the reference voltage Vr and the scan voltage Vs to the non-selection lines, that is, all of the remaining reference electrodes 5 and scan electrodes 6, respectively. Specifically, the reference driver 8 and the scan driver 9 apply, as the non-selection voltage, a voltage value that is, for example, the middle of the high voltage and the low voltage, that is, an intermediate voltage that is, the 3 rd voltage and the 4 th voltage, to all of the remaining reference electrodes 5 and scan electrodes 6. Thus, in each pixel of the non-selection line, the conductive liquid 16 is not unnecessarily changed but is stationary on the effective display region P1 side or the non-effective display region P2 side, and the display color on the display surface side is not changed.

In the case of performing the display operation as described above, the combination of voltages applied to the reference electrode 5, the scanning electrode 6, and the signal electrode 4 is shown in table 1. As shown in table 1, the operation of the conductive liquid 16 and the display color on the display surface side correspond to the applied voltage. In table 1, the high voltage, the low voltage, and the intermediate voltage are indicated by "H", "L", and "M", respectively (the same applies to table 2 below).

Watch l

< actions in select line >

In the selection line, when, for example, a high voltage is applied to the signal electrode 4, a high voltage is applied between both the reference electrode 5 and the signal electrode 4, and therefore no potential difference is generated between these reference electrode 5 and the signal electrode 4. On the other hand, since a low voltage is applied to the scanning electrodes 6, a potential difference is generated between the signal electrodes 4 and the scanning electrodes 6. Therefore, the conductive liquid 16 moves inside the display space S to the scanning electrode 6 which generates a potential difference with respect to the signal electrode 4. As a result, as shown in fig. 4 (b), the conductive liquid 16 moves to the side of the non-effective display region P2, the oil 17 moves to the reference electrode 5, and the illumination light from the backlight 18 is allowed to reach the color filter portion 11 r. Thereby, the display color on the display surface side is in a red display (CF colored display) state of the color filter portion 11 r. In the image display device 1, in all three adjacent RGB pixels, the conductive liquid 16 moves to the non-effective display region P2 to perform CF color display, and at this time, the red light, the green light, and the blue light from the RGB pixels are mixed into white light to perform white display.

On the other hand, when a low voltage is applied to the signal electrode 4 in the selection line, a potential difference occurs between the reference electrode 5 and the signal electrode 4, and a potential difference does not occur between the signal electrode 4 and the scanning electrode 6. Therefore, the conductive liquid 16 moves inside the display space S toward the reference electrode 5, which generates a potential difference with respect to the signal electrode 4. As a result, as shown in fig. 4 (a), the conductive liquid 16 moves to the effective display region P1 side, and the illumination light from the backlight 18 is prevented from reaching the color filter portion 11 r. Thereby, the display color on the display surface side is in a state of black display (non-CF colored display) of the conductive liquid 16.

< action of non-selection >

In the non-selection line, for example, a high voltage is applied to the signal electrode 4, and the conductive liquid 16 is maintained in a state of being stationary at the current position, and the current display color is maintained. That is, since the intermediate voltage is applied to both the reference electrode 5 and the scanning electrode 6, the same potential difference is generated between the reference electrode 5 and the signal electrode 4 and between the scanning electrode 6 and the signal electrode 4. As a result, the display color is maintained without being changed from the current black display or CF color display.

Similarly, when a low voltage is applied to the signal electrode 4 in the non-selection line, the conductive liquid 16 is maintained in a state of being stationary at the current position, and the current display color is maintained. That is, since the intermediate voltage is applied to both the reference electrode 5 and the scanning electrode 6, the same potential difference is generated between the reference electrode 5 and the signal electrode 4 and between the scanning electrode 6 and the signal electrode 4.

As described above, in the non-selection line, the signal electrode 4 is at either of the high voltage and the low voltage, and the conductive liquid 16 is stationary without moving, and the display color on the display surface side does not change.

On the other hand, as described above, the conductive liquid 16 can be moved in the selection line in accordance with the voltage applied to the signal electrode 4, and the display color on the display surface side can be changed.

In the image display device 1, for example, as shown in fig. 5, the display color of each pixel on the selection line is CF-colored (red, green, or blue) in the color filter portions 11r, 11g, and 11b or non-CF-colored (black) in the conductive liquid 16 in accordance with the voltage applied to the signal electrode 4 corresponding to each pixel, by the combination of the applied voltages shown in table 1. When the reference driver 8 and the scan driver 9 respectively perform the scanning operation from the left to the right in fig. 5 on the selection lines of the reference electrode 5 and the scan electrode 6, for example, the display colors of the pixels in the display portion of the pixel display device 1 also change sequentially from the left to the right in fig. 5. Thus, by performing the high-speed scanning operation for selecting lines by the reference driver 8 and the scan driver 9, the display color of each pixel of the display portion can be changed at high speed in the pixel display device 1. By applying the signal voltage Vd to the signal electrodes 4 in synchronization with the scanning operation of the selection lines, the pixel display device 1 can display various information including moving images based on the pixel input signals from the outside.

The combination of voltages applied to reference electrode 5, scan electrode 6, and signal electrode 4 is not limited to table 1, and may be the combination shown in table 2.

TABLE 2

That is, the reference driver 8 and the scan driver 9 apply a low voltage (2 nd voltage) and a high voltage (1 st voltage) as selection voltages to the reference electrode 5 and the scan electrode 6 in this order in a predetermined direction from, for example, the left side to the right side of the figure, and perform a scanning operation as a selection line. In the selection line, the signal driver 7 applies a high voltage or a low voltage as the signal voltage Vd to the corresponding signal electrode 4 in accordance with an external image input signal.

On the other hand, the reference driver 8 and the scan driver 9 apply an intermediate voltage as a non-drive voltage to the non-selection lines, that is, all the other reference electrodes 5 and scan electrodes 6.

< actions in select line >

When a low voltage is applied to the signal electrode 4 in the selection line, for example, a low voltage is applied between both the reference electrode 5 and the signal electrode 4, and therefore no potential difference is generated between these reference electrode 5 and the signal electrode 4. On the other hand, since a high voltage is applied to the scanning electrodes 6, a potential difference is generated between the signal electrodes 4 and the scanning electrodes 6. Therefore, the conductive liquid 16 moves inside the display space S to the scanning electrode 6 which generates a potential difference with respect to the signal electrode 4. As a result, as shown in fig. 4 (b), the conductive liquid 16 moves to the side of the non-effective display region P2, the oil 17 moves to the reference electrode 5, and the illumination light from the backlight 18 is allowed to reach the color filter portion 11 r. Thereby, the display color on the display surface side is in a red display (CF color display) state of the color filter portion 11 r. In addition, as in the case shown in table 1, when CF-colored display is performed in all three pixels of adjacent RGB, white display is performed.

On the other hand, when a high voltage is applied to the signal electrode 4 in the selection line, a potential difference occurs between the reference electrode 5 and the signal electrode 4, and a potential difference does not occur between the signal electrode 4 and the scanning electrode 6. Therefore, the conductive liquid 16 moves inside the display space S to the reference electrode 5 which generates a potential difference with respect to the signal electrode 4. As a result, as shown in fig. 4 (a), the conductive liquid 16 moves to the effective display region P1 side, and the illumination light from the backlight 18 is prevented from reaching the color filter 11 r. Thereby, the display color on the display surface side becomes a black display (non-CF colored display) state of the conductive liquid 16.

< actions in unselected line >

When a low voltage is applied to the signal electrode 4 in the non-selection line, for example, the conductive liquid 16 is maintained in a state of being stationary at the current position, and the current display color is maintained. That is, since the intermediate voltage is applied to both the reference electrode 5 and the scanning electrode 6, the same potential difference is generated between the reference electrode 5 and the signal electrode 4 and between the scanning electrode 6 and the signal electrode 4. As a result, the display color is maintained without being changed from the current black display or CF color display.

Similarly, when a high voltage is applied to the signal electrode 4 in the non-selection line, the conductive liquid 16 is maintained in a state of being stationary at the current position, and the current display color is maintained. That is, since the intermediate voltage is applied to both the reference electrode 5 and the scanning electrode 6, the same potential difference is generated between the reference electrode 5 and the signal electrode 4 and between the scanning electrode 6 and the signal electrode 4.

As described above, in the case shown in table 2, as in the case shown in table 1, the signal electrode 4 is set to either a high voltage or a low voltage in the non-selection line, the conductive liquid 16 does not move and is stationary, and the display color on the display surface side does not change.

On the other hand, as described above, the conductive liquid 16 can be moved in the selection line in accordance with the voltage applied to the signal electrode 4, and the display color on the display surface side can be changed.

In addition, in the image display device 1 of the present embodiment, in addition to the combinations of the applied voltages shown in tables 1 and 2, the voltage applied to the signal electrode 4 can be changed between a high voltage and a low voltage depending on the information displayed on the display surface side, in addition to the two values of the high voltage or the low voltage. That is, in the image display device 1, gradation display can be performed by controlling the signal voltage Vd. This makes it possible to form the display element 10 having excellent display performance.

Next, the display operation for each line in the image display device 1 according to the present embodiment will be described in more detail with reference to fig. 6 and 7. In the following description, for the sake of simplicity of explanation, the case where the number of pixels in the X direction and the Y direction is (3 × 3) will be described as an example.

Fig. 6 is a diagram illustrating a more specific operation example of the image display device, and fig. 6 (a) and 6 (b) are diagrams illustrating an initial state and a state in a next stage of the initial state, respectively. Fig. 7 is a diagram illustrating a more specific operation example of the image display device, and fig. 7 (a) and 7 (b) are diagrams sequentially illustrating states at a stage subsequent to the state shown in fig. 6 (b). Fig. 6 and 7 show the operation of the conductive liquid 16 of each pixel as viewed from the upper substrate 2 side, and the oil 17 and the like are not shown.

As shown in fig. 6 (a), 9 pixels are formed in a space surrounded by ribs 14a and 14b in units of intersections of signal electrodes 41, 42, and 43 with a pair of reference electrodes 51 and scanning electrodes 61, a pair of reference electrodes 52 and scanning electrodes 62, and a pair of reference electrodes 53 and scanning electrodes 63. In the initial state shown in fig. 6 (a), no voltage is applied to the signal electrodes 41 to 43, the reference electrodes 51 to 53, and the scanning electrodes 61 to 63. In this initial state, as shown in fig. 6 (a), the conductive liquid 16 is located on the effective display region P1 side in each pixel.

Then, in fig. 6 (b), when the pixel column on the left side is selected as the selection line, a high voltage and a low voltage are applied to the reference electrode 51 and the scanning electrode 61, respectively, and the conductive liquid 16 is allowed to move. At this time, for example, when a low voltage is applied to the signal electrodes 41 and 43 and a high voltage is applied to the signal electrode 42, as shown in fig. 6 (b), only the conductive liquid 16 of the pixels in the second row moves toward the scanning electrode 61, that is, toward the non-effective display region P2, and CF color display is performed. The conductive liquid 16 of the pixels in the first row and the third row is stopped on the reference electrode 51 side, that is, on the effective display region P1 side, and non-CF colored display is performed.

On the other hand, since the pixel column at the center and the pixel column on the right side are non-selection lines, even if an intermediate voltage is applied to the reference electrodes 52 and 53 and the scanning electrodes 62 and 63, the voltage application described above is performed to the signal electrodes 41 to 43, the conductive liquid 16 of the corresponding pixel does not move.

Then, in fig. 7 (a), when the central pixel column is selected as the selection line, a high voltage and a low voltage are applied to the reference electrode 52 and the scan electrode 62, respectively, and the conductive liquid 16 is allowed to move. At this time, for example, when a high voltage is applied to the signal electrodes 41 and 43 and a low voltage is applied to the signal electrode 42, the conductive liquid 16 of the pixels in the first row and the third row moves to the scanning electrode 62 side, that is, the non-effective display region P2, and CF color display is performed, as shown in fig. 7 (a). The conductive liquid 16 of the pixels in the second row is stopped on the reference electrode 52 side, that is, on the effective display area side, and non-CF colored display is performed.

On the other hand, since the left pixel column and the right pixel column are non-selection lines, even if the intermediate voltage is applied to the reference electrodes 51 and 53 and the scanning electrodes 61 and 63, the voltage application described above is performed to the signal electrodes 41 to 43, the conductive liquid 16 of the corresponding pixel does not move.

Then, in fig. 7 (b), when the pixel column on the right side is selected as the selection line, a high voltage and a low voltage are applied to the reference electrode 53 and the scanning electrode 63, respectively, and the conductive liquid 16 is allowed to move. At this time, for example, when a low voltage is applied to the signal electrodes 41 and 43 and a high voltage is applied to the signal electrode 42, the conductive liquid 16 of the pixels in the second row moves to the scanning electrode 63 side, that is, the non-effective display region P2, as shown in fig. 7 (b), and CF color display is performed. The conductive liquid 16 of the pixels in the first row and the third row is stopped on the reference electrode 53 side, that is, the effective display region P1, and non-CF colored display is performed.

On the other hand, since the pixel column on the right side and the pixel column in the center are non-selection lines, even if an intermediate voltage is applied to the reference electrodes 51 and 52 and the scanning electrodes 61 and 62, the voltage application described above is performed to the signal electrodes 41 to 43, and the conductive liquid 16 of the corresponding pixel does not move.

Next, the operation of the conductive liquid 16 in an arbitrary pixel will be specifically described with reference to fig. 8. In the following description, the operation of the second row pixel (hereinafter, referred to as pixel (2, 1)) of the left pixel column among the pixels shown in fig. 6 and 7 will be described as an example.

Fig. 8 is a timing chart showing the magnitude and the application time of the applied voltage in a more specific operation example of the image display device.

As shown in fig. 8 (a) to 8 (c), when a low voltage, a high voltage, and a high voltage are applied to the scan electrode 61, the reference electrode 51, and the signal electrode 42, respectively, during a period from time T1 to time T2, the conductive liquid 16 moves from the initial state shown in fig. 6 (a) to the state shown in fig. 6 (b) in the pixel (2, 1).

Thereafter, since the intermediate voltage is applied to the scan electrode 61 and the reference electrode 51 during the period from the time T2 to the time T3 and the period from the time T3 to the time T4, the pixels (2, 1) are included in the non-selection lines, and the movement of the conductive liquid 16 is prevented. That is, although the low voltage and the high voltage are applied to the signal electrode 42 during the period from the time T2 to the time T3 and during the period from the time T3 to the time T4, as shown in fig. 7 (a) and 7 (b), the conductive liquid 16 of the pixel (2, 1) is stationary as shown in fig. 6, and the display color of the pixel (2, 1) is not changed.

Specific voltage values of the high voltage, the intermediate voltage, and the low voltage are, for example, +8V, 0V, and-8V. The time intervals between the time T1 and the time T2, between the time T2 and the time T3, and between the time T3 and the time T4 are, for example, about 0.5 seconds. In addition, the allowable voltage values of the high voltage and the low voltage are about +30V and-30V, respectively.

In the display element 10 of the present embodiment having the above-described configuration, voltages in a predetermined voltage range between a high voltage (1 st voltage) and a low voltage (2 nd voltage) can be applied to the signal electrode 4, the reference electrode 5, and the scan electrode 6 independently of each other. Thus, unlike the conventional example, the display element 10 of the present embodiment can prevent the structure from being complicated and large-sized even when matrix driving is performed. In addition, the same intermediate voltages (3 rd voltage and 4 th voltage) are applied to the reference electrode 5 and the scan electrode 6. Thus, in the display element 10 of the present embodiment, even when matrix driving is performed, unnecessary fluctuation of the conductive liquid 16 can be suppressed, and a display element with good display quality in which deterioration of display quality due to fluctuation of the conductive liquid 16 is prevented can be configured.

Here, the experimental results of the test experiments conducted by the inventors of the present invention and the like are explained more specifically with reference to fig. 9.

Fig. 9 is a diagram for explaining specific effects of the present embodiment, fig. 9 (a) and 9 (b) are schematic side views showing the display element and a plan view showing an image region of the display element, respectively, and fig. 9 (c) and 9 (d) are schematic side views showing a comparative product and a plan view showing a pixel region of the comparative product, respectively.

In the above test experiment, the present embodiment shown in fig. 9 (a) and the comparative example shown in fig. 9 (c) were prepared, and the conductive liquid was observed when the following voltage application was performed. In addition, the size of the effective display region where the conductive liquid is not visually recognized, that is, the area of the opening portion, was compared when the conductive liquid was left at rest on the non-effective display region side.

Specifically, the area of the effective display region P1 and the area of the effective display region Px1 are compared, where the effective display region P1 is the effective display region P1 of the pixel P shown in fig. 9 (b) in the case where, for example, a low voltage is applied to the signal electrode 4 and an intermediate voltage is applied to the reference electrode 5 and the scanning electrode 6 in the present embodiment, and the effective display region Px1 is the effective display region Px1 which is opposed to the non-effective display region Px2 in the pixel region Px shown in fig. 9 (d) in the case where, for example, a low voltage is applied to the signal electrode 4x and a high voltage is applied to the reference electrode 5x and the scanning electrode 6x in the comparative example.

As a result, it was confirmed that the area of the opening can be increased by about 25% in the present embodiment compared to the comparative example. This is because, as shown in fig. 9 (a) and 9 (c), the potential difference between the signal electrode 4 and the reference electrode 5 is half that between the signal electrode 4x and the reference electrode 5x of the comparative example, and the wettability of the conductive liquid 16 can be improved as compared with the comparative example, and the amount of wetting diffusion can be reduced inside the display space. As a result, as shown in fig. 9 (a) and 9 (c), in the present embodiment, the size of the black matrix portion 11s can be made smaller than the size of the black matrix portion 11sx of the comparative example, and the effective display region P1 can be increased.

In the case shown in fig. 9 (a), a case where a low voltage is applied to the signal electrode 4 and an intermediate voltage is applied to the reference electrode 5 and the scanning electrode 6 is exemplified, but even in the case where a high voltage is applied to the signal electrode 4 and an intermediate voltage is applied to the reference electrode 5 and the scanning electrode 6, the potential difference between the signal electrode 4 and the reference electrode 5 of the test article of the present embodiment can be made half of the potential difference between the signal electrode 4x and the reference electrode 5x of the comparative article. That is, even when a high voltage is applied to the signal electrode 4, unnecessary fluctuation of the conductive liquid 16 can be suppressed and the effective display region P1 can be increased, as in the case of applying a low voltage to the signal electrode 4.

In addition, in the image display device (electrical apparatus) 1 of the present embodiment, since the display element 10 is used for the display portion, the high-performance image display device 1 having the display portion with excellent display quality can be easily configured.

In the display element 10 of the present embodiment, the plurality of reference electrodes 5 and the plurality of scanning electrodes 6 are alternately provided on the lower substrate (2 nd substrate) 3 side so as to intersect the plurality of signal electrodes 4. In the display element 10 of the present embodiment, the signal driver (signal voltage applying section) 7, the reference driver (reference voltage applying section) 8, and the scan driver (scan voltage applying section) 9 apply the signal voltage Vd, the reference voltage Vr, and the scan voltage Vs to the signal electrodes 4, the reference electrodes 5, and the scan electrodes 6. Thus, in the present embodiment, the matrix drive type display device 10 having excellent display quality can be easily configured.

In the display device 10 of the present embodiment, since the display operation is performed by the illumination light from the backlight 18, it is possible to perform an accurate display operation even in the case of insufficient external light or at night. In addition, in the present embodiment, a high-luminance display element having a large light adjustment range and capable of easily performing highly accurate gradation control can be easily configured.

< embodiment 2 >

Fig. 10 (a) and 10 (b) are sectional views showing the essential structure of the display element according to embodiment 2 of the present invention in the case of performing non-CF color display and CF color display, respectively. In the figure, the main differences between the present embodiment and the above embodiment 1 are: a diffusion reflection plate is provided on the back surface side of the lower substrate, and a reflection-type display element is configured. Note that the same reference numerals are given to elements common to those in embodiment 1, and redundant description thereof is omitted.

That is, as shown in fig. 10, in the present embodiment, the diffuse reflection plate 19 is integrally provided on the rear surface side of the lower substrate 3, and constitutes the reflective display element 10. The diffuse reflection plate 19 includes, for example, a transparent polymer resin such as an acrylic resin and a plurality of types of fine particles having different refractive indices added to the inside of the polymer resin, and functions to reflect external light incident from the upper substrate 2 side (display surface side) to the display surface side. In the diffuse reflection plate 19, the plurality of types of fine particles include fine particles of titanium oxide and aluminum oxide having a large refractive index and fine particles of hollow polymer having a small refractive index, and can efficiently reflect external light to the display surface side.

As shown in fig. 10 a, in the display element 10 of the present embodiment, when the conductive liquid 16 is held between the color filter portion 11r and the reference electrode 5, external light from the display surface side is blocked by the conductive liquid 16, and black display (non-CF color display) is performed. On the other hand, as shown in fig. 10 b, when the conductive liquid 16 is held between the black matrix portion 11s and the scanning electrode 6, external light from the display surface side reaches the diffuse reflection plate 19 without being blocked by the conductive liquid 16, is reflected by the diffuse reflection plate 19 toward the display surface side, and then passes through the color filter portion 11r, thereby performing red display (CF color display).

With the above configuration, the present embodiment can exhibit the same operation and effect as those of embodiment 1. In the present embodiment, since the diffuse reflection plate (light reflection unit) 19 reflects the external light incident from the outside to perform the display operation, the display element 10 and the image display device 1 which are low in power consumption and thin can be easily configured.

In the above description, the diffuse reflection plate 19 is provided on the rear surface side of the lower substrate 3, but the present invention is not limited to this as long as the light reflection portion is provided on the 2 nd substrate side provided on the non-display surface side. For example, the dielectric layer 13 may be formed of a white plate made of synthetic resin having a reflecting function, thereby serving as both the dielectric layer and the diffuse reflection plate. The lower substrate 3 may be formed of the white plate, and thus the lower substrate and the diffuse reflection plate may be used in combination.

< embodiment 3 >

Fig. 11 (a) and 11 (b) are sectional views showing the essential structure of the display element according to embodiment 3 of the present invention in the non-CF colored display mode and the CF colored display mode, respectively. In the figure, the main differences between the present embodiment and the above embodiment 1 are: a semi-transmissive plate having a diffuse reflection section and a transparent section arranged in parallel is provided on the back surface side of the lower substrate, and a semi-transmissive display element is configured. Note that the same reference numerals are given to elements common to those in embodiment 1, and redundant description thereof is omitted.

That is, as shown in fig. 11, in the present embodiment, the semi-transmissive plate 20 is integrally provided on the rear surface side of the lower substrate 3, and constitutes the semi-transmissive display element 10. The semi-transmissive plate 20 is provided with a transparent portion 20a and a diffuse reflection portion 20b as light reflection portions, which are arranged in parallel with each other in the left-right direction of fig. 11. Specifically, the transparent portion 20a and the diffuse reflection portion 20b are provided on the rear surface of the lower substrate 3, and divide the effective display region P1 (fig. 2) of the pixel into two parts. The transparent portion 20a is made of a transparent synthetic resin such as acrylic resin, and allows illumination light from the backlight 18 to transmit therethrough. In addition, similarly to the diffuse reflection plate 19 shown in fig. 10, the diffuse reflection portion 20b uses a transparent polymer resin containing a plurality of types of fine particles, and diffusely reflects the external light from the display surface side.

In the display element 10 of the present embodiment, as shown in fig. 11 (a), when the conductive liquid 16 is held between the color filter portion 11r and the reference electrode 5, the external light from the display surface side and the illumination light from the backlight 18 are blocked by the conductive liquid 16, and black display (non-CF color display) is performed. On the other hand, as shown in fig. 11 (b), when the conductive liquid 16 is held between the black matrix portion 11s and the scanning electrode 6, external light from the display surface side reaches the diffuse reflection portion 20b without being blocked by the conductive liquid 16, and passes through the color filter portion 11r after being reflected to the display surface side by the diffuse reflection portion 20 b. Similarly, the illumination light from the backlight 18 passes through the color filter portion 11r, and the display element 10 of the present embodiment performs red display (CF color display) by the external light and the illumination light.

With the above configuration, the present embodiment can exhibit the same operation and effect as those of embodiment 1. In addition, in the present embodiment, since the display operation is performed by the external light reflected by the diffuse reflection portion (light reflection portion) 20a and the illumination light from the backlight device 18, the display element 10 and the image display device 1 having high luminance, which can reduce the power consumption of the backlight device 18, expand the light control range, and easily perform highly accurate gradation control, can be easily configured.

In the above description, the case where the semi-transmissive plate 20 having the transparent portion 20a and the diffusive reflective portion 20b is provided on the rear surface side of the lower substrate 3 has been described, but the present invention is not limited to this as long as the light reflective portion and the transparent portion are provided in parallel on the 2 nd substrate side provided on the non-display surface side. For example, the lower substrate 3 may be formed of a white plate made of synthetic resin having a transparent portion and a reflecting function, thereby using both the lower substrate and the diffuse reflection plate.

Furthermore, the above embodiments are all examples and are not limiting. The technical scope of the present invention is defined by the claims, and all modifications within the structural and equivalent ranges described therein are included in the technical scope of the present invention.

For example, although the present invention has been described as being applied to an image display device provided with a display portion capable of displaying a color image in the above description, the present invention is not limited to any particular one as long as the present invention is an electrical device provided with a display portion for displaying information including characters and images, and can be suitably applied to, for example, a portable information terminal such as a PDA such as an electronic organizer, a display device attached to a personal computer or a television, or other electrical devices provided with various display portions such as electronic paper.

In the above description, the case where the display element of the electrowetting type is configured to move the conductive liquid by applying an electric field to the conductive liquid has been described, but the display element of the present invention is not limited to this, and any electric field induction type display element may be used as long as the display element can change the display color on the display surface side by operating the conductive liquid in the display space by an external electric field, and the present invention is applicable to electric field induction type display elements of other types such as the electrodialysis type, the electrophoresis type, and the dielectrophoresis type.

However, in the case of forming the electrowetting display device as described in the above embodiments, the conductive liquid can be moved at a high speed with a low driving voltage. Further, since 3 electrodes are provided to slide the conductive liquid, it is possible to easily increase the switching speed of the display color on the display surface side and reduce power consumption, compared with the case where the shape of the conductive liquid is changed. In addition, since the display color is changed in accordance with the movement of the conductive liquid in the electrowetting display device, there is no viewing angle dependency unlike a liquid crystal display device or the like, which is preferable. Further, since it is not necessary to provide a switching element for each pixel, a matrix drive type display element having a simple structure can be configured at low cost, which is also preferable in this respect. Further, since a birefringence material such as a liquid crystal layer is not used, it is also preferable in that a display element with high luminance which is used for information display and is excellent in light utilization efficiency of external light can be easily configured.

In the above description, the case where the signal electrode is provided on the substrate (1 st substrate) side and the reference electrode and the scan electrode are provided on the lower substrate (2 nd substrate) side has been described. However, in the present invention, the signal electrode, the reference electrode, and the scanning electrode may be configured such that a voltage within a predetermined voltage range between the 1 st voltage and the 2 nd voltage can be applied independently of each other, the signal electrode is provided inside the display space so as to be in contact with the conductive liquid, and the reference electrode and the scanning electrode are provided on one of the 1 st substrate and the 2 nd substrate in a state of being electrically insulated from the conductive liquid. Specifically, for example, the signal electrode may be provided on the 2 nd substrate and the rib, and the reference electrode and the scan electrode may be provided on the 1 st substrate.

In addition, in the above description, the case where the reference electrode and the scanning electrode are provided on the effective display region side and the non-effective display region side, respectively, has been described, but the present invention is not limited to this, and the reference electrode and the scanning electrode may be provided on the non-effective display region side and the effective display region side, respectively.

In the above description, the case where the reference electrode and the scanning electrode are provided on the surface of the lower substrate (2 nd substrate) on the display surface side has been described, but the present invention is not limited to this, and the reference electrode and the scanning electrode embedded in the 2 nd substrate made of an insulating material may be used. In the case of such a structure, the 2 nd substrate can also serve as the dielectric layer, and the provision of the dielectric layer can be omitted. Further, the signal electrodes may be provided directly on the 1 st substrate and the 2 nd substrate which also serve as the dielectric layers, and the signal electrodes may be provided inside the display space.

In the above description, the intermediate voltage between the 3 rd voltage and the 4 th voltage which are the same as each other is applied to the reference electrode and the scan electrode, but the present invention may be applied as long as the 3 rd voltage between the 1 st voltage and the 2 nd voltage is applied to the reference electrode and the 4 th voltage substantially the same as the 3 rd voltage is applied to the scan electrode.

However, as described in the above embodiments, it is preferable that the conductive liquid be in a more stable state when an intermediate voltage that is an intermediate value between the values of the high voltage (1 st voltage) and the low voltage (2 nd voltage) is applied, and that the display quality be reliably improved.

In the above description, the reference electrode and the scanning electrode are made of transparent electrode materials, but in the present invention, only one of the reference electrode and the scanning electrode provided so as to face the effective display region of the pixel may be made of a transparent electrode material, and the other electrode not facing the effective display region may be made of an opaque electrode material such as aluminum, silver, chromium, or another metal.

In the above description, the case where the reference electrode and the scanning electrode are in a band shape has been described, but the shapes of the reference electrode and the scanning electrode in the present invention are not limited to this. For example, a display element having a lower light use efficiency for information display than that of the transmissive type may be formed in a shape in which light loss is less likely to occur, such as a linear shape or a mesh shape.

In the above description, the case where the signal electrode is formed using a linear wiring has been described, but the signal electrode of the present invention is not limited to this, and a wiring having another shape such as a mesh wiring may be used.

However, in the case where the shape of the signal electrode is determined by the transmittances of the reference electrode and the scanning electrode using the transparent electrode as in the above-described embodiments, even when the signal electrode is formed using an opaque material, it is possible to prevent shadows of the signal electrode from appearing on the display surface side, and to suppress a reduction in display quality, which is preferable, and in the case where the linear wiring is used, it is possible to reliably suppress the reduction in display quality, which is more preferable.

In the above description, the case where an aqueous solution of potassium chloride is used as the conductive liquid and the signal electrode is formed of at least one of gold, silver, copper, platinum, and palladium has been described, but the present invention is not limited thereto as long as the signal electrode is provided inside the display space and is in contact with the conductive liquid, and the signal electrode is made of a material electrochemically inert to the conductive liquid. Specifically, as the conductive liquid, an electrolyte containing zinc chloride, potassium hydroxide, sodium hydroxide, alkali metal sodium hydroxide, zinc oxide, sodium chloride, lithium salt, phosphoric acid, alkali metal carbonate, ceramics having oxygen ion conductivity, or the like can be used. In addition, as the solvent, an organic solvent such as alcohol, acetone, formamide, or ethylene glycol can be used in addition to water. Further, the conductive liquid of the present invention may be an ionic solution (normal temperature molten salt) containing a cation such as a pyridine type, alicyclic amine type, or aliphatic amine type, and an anion such as a fluoride ion or a fluorine type such as a trifluoromethanesulfonate.

Among these, in the case where an aqueous solution in which a predetermined electrolyte is dissolved is used as the conductive liquid as in the above embodiments, it is preferable that a display element which is excellent in handling property and can be manufactured easily be configured.

The signal electrode of the present invention can be a passive state including an electrode body made of a conductive metal such as aluminum, nickel, iron, cobalt, chromium, titanium, tantalum, niobium, or an alloy thereof, and an oxide film provided to cover the surface of the electrode body.

In particular, when at least one of gold, silver, copper, platinum, and palladium is used as the signal electrode as in the above embodiments, it is preferable to use a metal having a small ionization tendency, and to easily construct a long-life display element which can simplify the electrode, reliably prevent an electrochemical reaction with a conductive liquid, and prevent a decrease in reliability. Further, the metal having a small ionization tendency can make the interfacial tension generated at the interface with the conductive liquid small, and therefore, when the conductive liquid is not moved, the conductive liquid can be easily held in a stable state at a fixed position, which is preferable.

In the above description, the case of using the nonpolar oil has been described, but the present invention is not limited to this, and may be any insulating fluid as long as it is not mixed with the conductive liquid. For example, air may be used instead of oil. In addition, silicone oil or aliphatic hydrocarbon can be used as the oil.

However, as described in the above embodiments, in the case where the nonpolar oil incompatible with the conductive liquid is used, it is preferable that the droplets of the conductive liquid move more easily in the nonpolar oil than in the case where air and the conductive liquid are used, and the display color can be switched at high speed by moving the conductive liquid at high speed.

In the above description, the case where the pixels of respective colors of RGB are provided on the display surface side using the conductive liquid colored in black and the color filter layer has been described, but the present invention is not limited to this, and a plurality of pixel regions may be provided for each of a plurality of colors which can be displayed in full color on the display surface side. Specifically, conductive liquids colored in plural colors such as CMY, RGBYC, and the like of RGB, cyan (C), magenta (M), and yellow (Y) may be used.

In the above description, although the case where the color filter layer is formed on the surface of the upper substrate (1 st substrate) on the non-display surface side has been described, the present invention is not limited to this, and the color filter layer may be provided on the surface of the 1 st substrate on the display surface side and on the lower substrate (2 nd substrate) side. Specifically, as shown in fig. 12 (a) and 12 (b), the color filter layer 11 may be provided on the surface of the lower substrate (2 nd substrate) 3 on the display surface side. In this way, it is preferable that a display element which is easy to manufacture be easily configured in the case of using a color filter layer, as compared with the case of preparing conductive liquids of a plurality of colors. In addition, it is preferable that the color filter portion (opening portion) and the black matrix portion (light-shielding film) included in the color filter layer are used to appropriately and reliably set the effective display region and the ineffective display region in the display space.

The present invention is useful for a display element having a good display quality and capable of preventing a complicated and large-sized structure even when matrix driving is performed, and a high-performance electric apparatus using the display element.

Claims (12)

1. A display element is provided with:

a 1 st substrate disposed on the display surface side,

A 2 nd substrate disposed on the non-display surface side of the 1 st substrate to form a predetermined display space with the 1 st substrate,

An effective display region and an ineffective display region set in the display space, and

a conductive liquid sealed in the display space and movable to the effective display region side or the non-effective display region side,

the display color on the display surface side can be changed by moving the conductive liquid,

the display element is characterized in that:

the disclosed device is provided with:

a signal electrode provided inside the display space so as to be in contact with the conductive liquid;

a reference electrode provided on one of the 1 st substrate and the 2 nd substrate so as to be electrically insulated from the conductive liquid, the reference electrode being provided on one of the effective display region side and the non-effective display region side; and

a scanning electrode provided on one of the 1 st substrate and the 2 nd substrate so as to be electrically insulated from the conductive liquid and the reference electrode and provided on the other of the effective display region side and the non-effective display region side,

the signal electrode, the reference electrode, and the scan electrode are capable of applying a voltage within a predetermined voltage range between a 1 st voltage and a 2 nd voltage independently of each other,

a 3 rd voltage that is a voltage between the 1 st voltage and the 2 nd voltage is applied to the reference electrode, and a 4 th voltage that is substantially the same as the 3 rd voltage is applied to the scan electrode.

2. The display element according to claim 1, wherein:

a plurality of the signal electrodes are arranged along a predetermined arrangement direction,

a plurality of the above-mentioned reference electrodes and a plurality of the above-mentioned scan electrodes are disposed to alternate with each other and to cross the above-mentioned plurality of signal electrodes,

the display element includes:

a signal voltage applying unit which is connected to the plurality of signal electrodes and applies a signal voltage in a predetermined voltage range between the 1 st voltage and the 2 nd voltage to each of the plurality of signal electrodes based on information displayed on the display surface side;

a reference voltage applying unit that is connected to the plurality of reference electrodes and applies one of a selection voltage that allows the conductive liquid to move inside the display space in accordance with the signal voltage and a non-selection voltage that prevents the conductive liquid from moving inside the display space to each of the plurality of reference electrodes; and

and a scanning voltage applying unit which is connected to the plurality of scanning electrodes and applies one of a selection voltage which allows the conductive liquid to move in the display space in accordance with the signal voltage and a non-selection voltage which prevents the conductive liquid from moving in the display space to each of the plurality of scanning electrodes.

3. The display element according to claim 2, wherein:

a plurality of pixel regions are provided on the display surface side, and

each of the plurality of pixel regions is provided in units of an intersection of the signal electrode and the scanning electrode, and the display space is partitioned by a partition wall in each of the pixel regions.

4. The display element according to claim 3, wherein:

the plurality of pixel regions are provided corresponding to a plurality of colors that can be displayed in full color on the display surface side.

5. The display element according to any one of claims 1 to 4, wherein:

an insulating fluid immiscible with the conductive liquid and movable in the display space is sealed in the display space.

6. The display element according to any one of claims 1 to 5, wherein:

dielectric layers are laminated on the surfaces of the reference electrodes and the scanning electrodes.

7. The display element according to any one of claims 1 to 6, wherein:

the 1 st substrate and the 2 nd substrate adopt transparent sheets,

a backlight device is provided on the back side of the 2 nd substrate.

8. The display element according to any one of claims 1 to 6, wherein:

the 1 st substrate adopts a transparent sheet material,

a light reflector is provided on the 2 nd substrate.

9. The display element according to any one of claims 1 to 6, wherein:

the 1 st substrate adopts a transparent sheet material,

a light reflecting part and a transparent part which are arranged in parallel are arranged on the 2 nd substrate side,

a backlight device is provided on the back side of the light reflecting section and the transparent section.

10. The display element according to any one of claims 1 to 9, wherein:

the voltage values of the 3 rd voltage and the 4 th voltage are intermediate voltage values between the 1 st voltage and the 2 nd voltage.

11. The display element according to any one of claims 1 to 10, wherein:

the non-effective display region is set by a light shielding film arranged on one side of the 1 st substrate and the 2 nd substrate,

the effective display region is set by an opening formed in the light shielding film.

12. An electric appliance provided with a display unit for displaying information including characters and images, characterized in that:

the display device according to any one of claims 1 to 11 is used for the display unit.