The present invention relates to a display device capable of displaying color.
In electrophoretic display devices, a prescribed voltage is applied to electrodes to cause charged particles (charged flakes) dispersed in a medium (an insulating liquid) to migrate as appropriate to form the desired display image. In quick-response liquid powder display (QR-LPD) devices, a prescribed voltage is applied to electrodes to cause charged particles (charged flakes) dispersed in a gas to migrate as appropriate to form the desired display image.
In recent years, these display technologies have attracted attention because they can provide a paper-like viewing experience. By using oppositely charged white and black particles as the charged particles, the display device can be made reflective, negating the need for polarizing plates and allowing a particularly high white reflectance to be achieved.
For example, the Japanese Translation of PCT International Application Publication No. 2004-500583 discloses a microcapsule scheme commercialized by the E Ink Corporation and featured in products such as the Kindle. In this scheme, white charged particles and black charged particles charged in advance with different respective polarities are dispersed in an insulating liquid contained in transparent capsules 10-100 μm in diameter. By applying electric fields to the capsules using external electrodes, the charged particles can be made to migrate up or down in the capsules, thereby forming the desired display image.
Next, Japanese Patent Application Laid-Open Publication No. 2003-255401 and Japanese Patent Application Laid-Open Publication No. 2010-256560 disclose the quick-response liquid powder display (QR-LPD) technology commercialized by the Bridgestone Corporation and featured in products such as the Aerobee. This QR-LPD technology uses a gas as the dispersion medium in cells to achieve faster response times and enable display of video content.
In addition, the Japanese Translation of PCT International Application Publication No. 2003-526817 discloses an electrophoretic display device developed by SiPix Inc. that employs a microcup scheme.
These display devices utilize white charged particles to allow a high reflectance to be achieved during display of black and white images. In order to display color images, however, a color filter must be applied separately to the viewer-side substrate. This typically reduces the reflectance of the display.
Patent Document 1 discloses an in-plane electrophoretic display device 100 (shown in
As shown in the left microcell enclosed by ribs 107 in
Next, as shown in the right microcell enclosed by ribs 107 in
The portions enclosed by the ribs 107 are microcells, and the viewer-side substrate 101 and the rear substrate 105 are fixed together using a sealing material.
This display device 100 can display color without suffering reduced reflectance when displaying white.
Patent Document 1: Japanese Patent Application Laid-Open Publication, “Japanese Patent Application Laid-Open Publication No. 2005-031345 (Published on Feb. 3, 2005)”
However, the display device 100 disclosed in Patent Document 1 suffers from the following problem. As shown in
The present invention was made in view of such problems, and aims to provide a display device that exhibits high color purity and brightness and with which satisfactory color display can be achieved without reduced reflectance when displaying white.
In order to solve the abovementioned problems, the present display device includes:
a first substrate;
a second substrate facing the first substrate; and
a cell filled with an insulating medium between the first substrate and the second substrate;
wherein the cell includes white and black charged particles having different respective polarities, and
wherein the first substrate and second substrate are both provided with electrodes for controlling migration of the charged particles,
wherein the electrodes for controlling the migration of the charged particles include a first electrode, a second electrode, and a third electrode,
wherein the first electrode and the second electrode are controlled independently of one another and are both disposed on one of either the first substrate or the second substrate, and
wherein the third electrode is disposed on the other substrate from the one of the first substrate or the second substrate on which the first and second electrodes are disposed such that the third electrode overlaps one of either the first electrode or the second electrode in a plan view.
In past technologies, when displaying color, the white and black charged particles gather near the in-plane pair of electrodes. The white and black particles partially cover the reflector for emitting a prescribed color, leaving only a small aperture thereabove. Sufficient color purity and brightness cannot be achieved through this small aperture, and therefore the display device as a whole cannot provide satisfactory color display.
In the configuration of the present invention described above, the first electrode and the second electrode are both disposed on either the first substrate or the second substrate, and the third electrode is disposed on the opposite substrate from the substrate on which the first and second electrodes are disposed, such that the third electrode overlaps one of either the first electrode or the second electrode when viewed in a plan view. These electrodes make it possible to create electric fields between the substrates.
As a result, the space in between the substrates can be used to gather the white and black charged particles without spreading them widely across the plane between the substrates.
Moreover, by taking advantage of the electric potential between the electrodes that overlap with each other and the electrode that does not overlap with the other electrodes when viewed in a plan view, this configuration makes it easier to move the particles above the aperture towards the opposing electrodes.
This makes it possible to increase the aperture ratio and thereby provide a display device that exhibits high color purity and brightness and with which satisfactory color display can be achieved without reduced reflectance when displaying white.
As described above, the present display device includes electrodes for controlling the migration of the charged particles. These electrodes include a first electrode, a second electrode, and a third electrode. The first electrode and the second electrode can be controlled independently of one another and are both disposed on either the first substrate or the second substrate. The third electrode is disposed on the opposite substrate from the substrate on which the first and second electrodes are disposed, such that the third electrode overlaps one of either the first electrode or the second electrode when viewed in a plan view.
This makes it possible to provide a display device that exhibits high color purity and brightness and with which satisfactory color display can be achieved without reduced reflectance when displaying white.
Embodiments of the present invention will be described in detail below with reference to figures. However, characteristics of these embodiments such as the dimensions, materials, shapes, and relative arrangements of components described below are intended only as examples. The present invention shall not be interpreted as being limited to these examples.
Embodiment 1 of the present invention will be described below with reference to
As shown in
Furthermore, the array substrate 4 includes a transistor element TFT1 for controlling the first electrode 2 and a transistor element TFT2 for controlling the second electrode 3 in each cell 10.
Moreover, in the present embodiment, a flexible substrate can be used for the transparent substrate 1 in order to make the quick-response liquid powder display device 13 flexible. However, if a flexible display device is not required, a glass substrate or the like can be used for the transparent substrate 1.
Next, in the present embodiment the first electrode 2 and the second electrode 3 can be formed using a material that transmits visible light such as indium tin oxide (ITO) or indium zinc oxide (IZO).
Meanwhile, an opposite substrate 9 includes a transparent substrate 5 on which a third electrode (opposite electrode) 6 is formed in a frame shape that, when viewed in a plan view, overlaps the first electrode 2 which is itself formed in a frame shape that encloses the second electrode 3.
Next, a frame-shaped rib (barrier wall) 7 is formed so as to cover the center portion of the frame-shaped third electrode (opposite electrode) 6, thereby forming the cell 10.
Because the rib 7 only covers the center portion of the third electrode (opposite electrode) 6, a portion of the third electrode (opposite electrode) 6 is exposed in the cell 10. This exposed portion of the third electrode (opposite electrode) 6 overlaps the first electrode 2 when viewed in a plan view.
Next, color reflectors 8R, 8G, and 8B, which each reflect light of a prescribed range of wavelengths, are provided on the transparent substrate 5 in the cell 10 formed by the rib 7.
As shown in
In other words, in the quick-response liquid powder display device 13, the cell 10 reflects red light and is positioned adjacent to a cell that reflects green light and a cell that reflects blue light.
The colors reflected by the color reflectors as well as the pattern in which the color reflectors are arranged are not particularly limited and can be configured as appropriate.
Next, in the present embodiment, the cell 10 is filled with air as the insulating medium, and positively charged white charged particles 11 and negatively charged black charged particles 12 are inserted in the cell 10.
The white charged particles 11 are formed using titanium oxide and a charge control agent. The black charged particles 12 are formed using carbon black and a charge control agent.
Moreover, in the present embodiment the white charged particles 11 are given a positive charge and the black charged particles 12 are given a negative charge. However, the present invention is not limited to this charging scheme, and the white charged particles 11 and black charged particles 12 may also be charged in the opposite manner.
In the present embodiment, a flexible substrate can be used for the transparent substrate 5 in order to make the quick-response liquid powder display device 13 flexible. However, if a flexible display device is not required, a glass substrate or the like can be used for the transparent substrate 5.
Moreover, the third electrode (opposite electrode) 6 can be formed using a material that transmits visible light such as indium tin oxide (ITO) or indium zinc oxide (IZO). When the display device 13 is a reflective quick-response liquid powder display device, however, the third electrode (opposite electrode) 6 does not need to be formed using a transparent electrode that transmits visible light.
Moreover, an acrylic photoresist with high transmittance of visible light can be used for the rib 7, for example, but other materials can also be used.
This ensures that improved color brightness can be achieved when displaying white in the areas around the region that reflects red light.
As shown in
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively positive electric potential in order to make the negatively charged black charged particles 12 gather near the opposite substrate 9.
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6, such that the second electrode 3 has a positive electric potential relative to the first electrode 2. This more reliably moves any white charged particles 11 and black charged particles 12 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6 overlap when viewed in a plan view.
This configuration utilizes the space in between the substrates 4 and 9 to gather the white charged particles 11 and the black charged particles 12 without spreading them widely across the plane between the substrates 4 and 9.
Moreover, by taking advantage of the electric potential between the second electrode 3 that does not overlap with the other electrodes in a plan view and the first electrode 2 and third electrode (opposite electrode) 6 that do overlap with each other in a plan view, this configuration makes it easier to move any white charged particles 11 and black charged particles 12 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6 overlap when viewed in a plan view.
This makes it possible to provide a quick-response liquid powder display device 13 that exhibits high color purity and brightness and with which satisfactory color display can be achieved without reduced reflectance when displaying white.
Moreover, as shown in
In this configuration, the rib 7 has a tapered shape, which allows the white charged particles 11 and the black charged particles 12 to be present above the regions in which the color reflectors 8R, 8G, and 8B are not present. This enables an increased aperture ratio to be achieved when displaying white and black.
As shown in
It should be noted that in
As shown in
A gate electrode 14, a gate insulation film 15, and an oxide semiconductor layer 16 (an indium gallium zinc oxide layer, for example) are layered in order on a transparent substrate 1.
In the region in which the transistor element TFT1 is formed, source and drain electrodes 17S and 17D on the oxide semiconductor layer 16 are connected to an interlayer insulating film 18, and the first electrode 2 and the drain electrode 17D are electrically connected through a contact hole formed in the interlayer insulating film 18.
Meanwhile, in the region in which the transistor element TFT2 is formed, source and drain electrodes 17S′ and 17D′ on the oxide semiconductor layer 16 are connected to the interlayer insulating film 18, and the second electrode 3 and the drain electrode 17D′ are electrically connected through a contact hole formed in the interlayer insulating film 18.
In the present embodiment, the oxide semiconductor layer 16 is used for the semiconductor layer in order to maintain a large aperture and in consideration of power consumption; however, other types of semiconductor layers can be used.
As shown in
This configuration makes it possible to achieve a large aperture ratio when displaying color as well as to use the signal lines 17G, 17S, and 17S′ as a black mask (black matrix).
Moreover, in consideration of maintaining the aperture ratio, the signal lines 17G, 17S, and 17S′ may be formed using transparent electrodes.
As shown in
The overlapping portions of the rib 7 and the first electrode 2 form an alignment margin so that the effective electrode area in each cell does not change even if misalignment errors occur when fixing the substrates 4 and 9 to one another.
As shown in
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively negative electric potential in order to make the positively charged white charged particles 11 gather near the opposite substrate 9.
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6, such that the second electrode 3 has a negative electric potential relative to the first electrode 2. This more reliably moves any white charged particles 11 and black charged particles 12 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6 overlap when viewed in a plan view.
As shown in
Displaying color in this manner allows a high color purity to be achieved.
As shown in
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively positive electric potential in order to make the negatively charged black charged particles 12 gather near the opposite substrate 9.
As shown in
As shown in
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively negative electric potential in order to make the positively charged white charged particles 11 gather near the opposite substrate 9.
As shown in
Next, a process for manufacturing the quick-response liquid powder display device 13 will be described below with reference to
First, the (Ti/Al/Ti) gate electrode layer 14 is formed on the transparent substrate 1 (S1), and the gate electrode layer 14 is patterned using a photoresist process and an etching process (S2).
Next, the gate insulation film 15 is formed over the entire surface of the gate electrode layer 14 (S3), and the oxide semiconductor layer 16 is formed over the entire surface of the gate insulation film 15 (S4).
Next, the oxide semiconductor layer 16 is patterned using a photoresist process and an etching process (S5).
Then, the source and drain electrode layers 17S, 17D, 17S′, and 17D′ are formed on the entire surface of the oxide semiconductor layer 16 using an Al/Ti multilayer film (S6).
Next, the source and drain electrode layers 17S, 17D, 17S′, and 17D′ are patterned using a photoresist process and an etching process (S7).
Then, the interlayer insulating film 18 is formed on the entire surface of the source and drain electrode layers (S8), and the interlayer insulating film 18 is patterned and the contact holes are formed (S9).
Next, transparent electrodes made from ITO are formed on the interlayer insulating film 18 using sputtering (S10), and the drain electrodes 17D and 17D′ are electrically connected to the transparent electrodes through the contact holes.
Then, the transparent electrodes are patterned, and the first electrode 2 that is electrically connected to the transistor element TFT1 and the second electrode 3 that is electrically connected to the transistor element TFT2 are formed for each cell 10 (S11).
Finally, a sealing agent is applied around the edges of the substrate (S12), and the array substrate 4 is completed (S13).
Meanwhile,
First, the third electrode (opposite electrode) layer is formed on the transparent substrate 5 (S21), and the third electrode (opposite electrode) layer is patterned using a photoresist process and an etching process to form the third electrode (opposite electrode) 6 (S22).
Next, the rib 7 is applied on the third electrode (opposite electrode) 6 (S23), and the rib 7 is patterned using an exposure and development process such that the rib 7 only remains on the center portion of the third electrode (opposite electrode) 6 and such that both edges thereof are exposed (S24).
Then, color reflectors are formed in the region covered by the rib 7 using an inkjet process (S25).
Next, the white charged particles 11 and the black charged particles 12 are inserted in the region covered by the rib 7 (S26), and the opposite substrate 9 is completed (S27).
Finally, the array substrate 4 and the opposite substrate 9 are fixed to one another (S28), and the quick-response liquid powder display device 13 is completed (S29).
Embodiment 2 of the present invention will be described below with reference to
As shown in
Next, a transistor element TFT3 for controlling the fourth electrode 19 is provided on the opposite substrate 9.
As shown in
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6, such that the second electrode 3 has a positive electric potential relative to the first electrode 2. This more reliably moves any white charged particles 11 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6 overlap when viewed in a plan view.
Meanwhile, the third electrode (opposite electrode) 6 is grounded such that it takes a relatively positive electric potential in order to make the negatively charged black charged particles 12 gather near the opposite substrate 9. The fourth electrode 19 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6, such that the fourth electrode 19 has a negative electric potential relative to the third electrode (opposite electrode) 6. This more reliably moves any black charged particles 12 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6 overlap when viewed in a plan view.
This configuration allows an even higher aperture ratio to be achieved when the quick-response liquid powder display device 20 displays color.
Embodiment 3 of the present invention will be described below with reference to
As shown in
Embodiment 4 of the present invention will be described below with reference to
As shown in
The present embodiment is described using the LED elements 23R, 23G, and 23B as examples, but other types of elements can be used in each cell as long as those elements can emit light of different prescribed ranges of wavelengths at prescribed time intervals.
In the quick-response liquid powder display device 24, a fast response time can be achieved because each cell 10 is filled with air as the insulating medium. Also, by virtue of exhibiting this fast response time, the white charged particles 11 and black charged particles 12 can be used as a shutter when driving the three LED elements 23R, 23G, and 23B in a manner similar to that in a field-sequential system to make the LED elements emit light at different prescribed ranges of wavelengths at prescribed time intervals.
In this case a negative electric potential is applied to the first electrode 2 in order to make the positively charged white charged particles 11 gather near the array substrate 4.
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively positive electric potential in order to make the negatively charged black charged particles 12 gather near the opposite substrate 9.
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6, such that the second electrode 3 has a negative electric potential relative to the first electrode 2. This more reliably moves any white charged particles 11 and black charged particles 12 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6 overlap when viewed in a plan view.
As shown in
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively negative electric potential in order to make the positively charged white charged particles 11 gather near the opposite substrate 9.
Next, as shown in
Embodiment 5 of the present invention will be described below with reference to
In the present embodiment, an insulating isoparaffin liquid is used for the insulating medium, as in Embodiment 3.
a) shows the electrophoretic display device 40 when each cell formed by a microcapsule 33 is emitting red light and displaying black in the areas around the region emitting red light.
As shown in
Meanwhile, a third electrode (opposite electrode) 6a is grounded to give it a relatively negative electric potential in order to make positively charged white charged particles 31 gather near an opposite substrate 5, on which the third electrode (opposite electrode) 6a is provided.
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6a, such that the second electrode 3 has a negative electric potential relative to the first electrode 2. This more reliably moves any white charged particles 31 and black charged particles 32 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6a overlap when viewed in a plan view.
Moreover, a rib 7a is formed in a tapered shape so that the third electrode (opposite electrode) 6a can be formed on top of the rib 7a; however, the rib 7a in the present embodiment has a different shape than the rib 7 in Embodiments 1 to 4. The height of the rib 7a is set to be lower than the position at which the third electrode (opposite electrode) 6a will be formed.
Meanwhile,
As shown in
Meanwhile, the third electrode (opposite electrode) 6 is grounded to give it a relatively positive electric potential in order to make the negatively charged black charged particles 32 gather near the substrate 5.
It should be noted that the arrows in the figures indicate the direction of the electric field applied.
a) shows the electrophoretic display device device 40a when each cell is emitting red light and displaying black in the areas around the region emitting red light.
Meanwhile,
As shown in
Embodiment 6 of the present invention will be described below with reference to
As shown in
Meanwhile, the third electrode (opposite electrode) 6b provided on the substrate 1 is grounded to give the electrode a relatively positive electric potential in order to make the negatively charged black charged particles 32 gather near the substrate 1.
Next, the second electrode 19a is given an electric potential in between the electric potential of the first electrode 2a and the electric potential of the third electrode (opposite electrode) 6b, such that the second electrode 19a has a positive electric potential relative to the first electrode 2a. This more reliably moves any white charged particles 31 and black charged particles 32 remaining in the center area of the cell towards the region in which the first electrode 2a and the third electrode (opposite electrode) 6b overlap when viewed in a plan view.
It should also be noted that, as shown in
Moreover, the configuration described for the present embodiment may also be applied as appropriate to other cases in which cells are not formed using microcapsules (Embodiments 1 to 4 and Embodiment 7, for example).
Embodiment 7 of the present invention will be described below with reference to
In the present embodiment, air is used for the insulating medium.
As shown in
Meanwhile, a third electrode (opposite electrode) 6c is grounded to give it a relatively negative electric potential in order to make positively charged white charged particles 41 gather near the opposite substrate 5, on which the third electrode (opposite electrode) 6c is provided.
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6c, such that the second electrode 3 has a negative electric potential relative to the first electrode 2. This more reliably moves any white charged particles 41 and black charged particles 42 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6c overlap when viewed in a plan view.
Embodiment 8 of the present invention will be described below with reference to
As shown in
Meanwhile, the third electrode (opposite electrode) 6a is grounded to give it a relatively negative electric potential in order to make positively charged white charged particles 31 gather near the opposite substrate 5, on which the third electrode (opposite electrode) 6a is provided.
Next, the second electrode 3 is given an electric potential in between the electric potential of the first electrode 2 and the electric potential of the third electrode (opposite electrode) 6a, such that the second electrode 3 has a negative electric potential relative to the first electrode 2. This more reliably moves any white charged particles 31 and black charged particles 32 remaining in the center area of the cell towards the region in which the first electrode 2 and the third electrode (opposite electrode) 6a overlap when viewed in a plan view.
Moreover, the configuration described for the present embodiment may also be applied as appropriate to other cases in which cells are not formed using microcapsules (Embodiments 1 to 4 and Embodiment 7, for example).
In the present display device, it is preferable that the first electrode be formed to surround the second electrode and that the first electrode and third electrode be arranged to overlap when viewed in a plan view.
This configuration allows white and black charged particles to be gathered between the first electrode and third electrode.
Moreover, when displaying color, adjusting the electric potential of the first electrode and/or third electrode allows white or black to be displayed in the area around the aperture.
Displaying black in the area around the aperture allows improved color purity to be achieved, and displaying white in the area around the aperture allows improved color brightness to be achieved.
In the present display device, it is preferable that a first active element for controlling the first electrode and a second active element for controlling the second electrode be provided on one of the substrates.
This configuration allows the method for manufacturing the substrate on which the first active element and the second active element are formed to be separated from the method for manufacturing the other substrate (on which the third electrode is formed), thereby improving manufacturing yield and takt time.
In the present display device, it is preferable that the semiconductor layer provided for the first active element and the second active element be formed using an oxide layer containing at least one of the following elements: indium, gallium, and zinc.
This composition allows the size of the elements to be reduced and a larger aperture to be achieved in comparison with using other active elements such as those provided using an amorphous semiconductor layer.
Moreover, oxide semiconductor layers exhibit low leakage current and high pixel state retention (memory properties) in the off state, which makes it possible to drive the semiconductors at a lower frequency and thereby reduce power consumption.
In the present display device, it is preferable that the first electrode be formed to align with the edge of the cell and that the first electrode and the edge of the cell overlap partially when viewed in a plan view.
This configuration makes it possible to gather the white and black charged particles along the edges of the cell, thereby allowing a large aperture to be maintained when displaying color.
In the present display device, it is preferable that part of the cell be formed by a barrier wall provided on the opposite substrate.
In this configuration, in which the barrier wall is provided on the opposite substrate (on which the third electrode is formed), the effective electrode area of each cell does not change even if misalignment errors occur when fixing the first substrate and the second substrate to one another because the barrier wall shifts the same amount relative to the first electrode and second electrode provided on the facing substrate.
Moreover, the array process and barrier wall formation process can be separated until the first substrate and second substrate are fixed to one another, thereby improving yield and takt time.
In the present display device, it is preferable that the cross-section of the barrier wall become smaller as the height of the barrier wall increases.
This configuration, in which the cross-section of the barrier wall become smaller as the height of the barrier wall increases, gives the barrier wall a tapered shape, thereby allowing a larger aperture ratio to be achieved when displaying black or white.
In the present display device, it is preferable that the first active element for controlling the first electrode and the second active element for controlling the second electrode be provided on one of the substrates, and that the first active element, second active element, the signal line for the first active element, and the signal line for the second active element all be arranged to overlap with the barrier wall when viewed in a plan view.
This configuration makes it possible to achieve a large aperture ratio when displaying color as well as to use the signal line for the first active element and the signal line for the second active element as a black mask (black matrix).
In the present display device, it is preferable that the signal line for the first active element and the signal line for the second active element be formed using a transparent conductive film that transmits visible light.
This configuration allows a large aperture to be achieved because the signal line for the first active element and the signal line for the second active element are formed using a transparent conductive film that transmits visible light.
In the present display device, it is preferable that the third electrode be formed in a frame shape that lines up with the edge of the cell, and that a fourth electrode be provided in the interior region of the third electrode such that the fourth electrode is disposed oppositely to the second electrode.
Adjusting the electric potential of the fourth electrode makes it possible to more reliably move white and black charged particles away from the region transmitting light of a prescribed range of wavelengths.
In the present display device, it is preferable that a third active element for controlling the fourth electrode be provided on the other substrate.
This configuration allows the method for manufacturing the substrate on which the first active element and the second active element are formed to be separated from the method for manufacturing the other substrate on which the third active element is formed, thereby improving manufacturing yield and takt time.
In the present display device, it is preferable that the third active element and the signal line for the third active element be formed to overlap, when viewed in a plan view, with the barrier wall that forms part of the cell.
This configuration allows a large aperture ratio to be achieved when displaying color.
In the present display device, it is preferable that the semiconductor layer provided for the third active element be formed using an oxide layer containing at least one of the following elements: indium, gallium, and zinc.
This composition allows the size of the element to be reduced and a larger aperture to be achieved in comparison with using other active elements such as those provided using an amorphous semiconductor layer.
Moreover, oxide semiconductor layers exhibit low leakage current and high pixel state retention (memory properties) in the off state, which makes it possible to drive the semiconductors at a lower frequency and thereby reduce power consumption.
In the present display device, a reflective layer for emitting light of a prescribed range of wavelengths from the cell may be provided in the region that overlaps with the cell when viewed in a plan view.
This configuration makes it possible to provide a reflective display device.
Moreover, providing the reflective layer on the other substrate (on which the barrier wall and third electrode are formed) allows the reflective layer to be formed in the interior of the barrier wall of the cell using an inkjet process, for example. This can drastically reduce production time in comparison with using conventional photolithography processes.
In the present display device, the cell may be provided with light-emitting devices that emit light of different prescribed ranges of wavelengths at prescribed time intervals.
This configuration makes it possible to provide a display device equipped with light-emitting devices that can be driven as in a so-called field-sequential system to emit light of different prescribed ranges of wavelengths into the cell at prescribed time intervals.
In the present display device, it is preferable that air be used for the insulating medium.
Using air as the insulating medium makes it possible to provide a quick-response liquid powder display device that exhibits a fast response time.
The present display device may be provided with a backlight and a color filter layer that takes light from the backlight and transmits light of prescribed ranges of wavelengths into the cell.
This configuration makes it possible to provide a backlight-equipped transmissive display device.
In the present display device, the cell may be formed using a microcapsule.
This configuration makes it possible to provide a display device having cells formed using microcapsules.
In the present display device, the cell may be formed using the first substrate, the second substrate, and the barrier wall.
This configuration makes it possible to provide a display device having cells formed using the first substrate, the second substrate, and the barrier wall.
In the present display device, the cell may be formed using one of either the first substrate or the second substrate and barrier walls formed in the shape of alternating protrusions and recessions on the other substrate.
This configuration makes it possible to provide a display device having cells formed using one of either the first substrate or the second substrate and barrier walls formed in the shape of alternating protrusions and recessions on the other substrate.
The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the scope of the claims. Therefore, embodiments obtained by appropriately combining the techniques disclosed in different embodiments are included in the technical scope of the present invention.
The present invention is suitable for use in quick-response liquid powder display devices and electrophoretic display devices that are capable of displaying color.
Number | Date | Country | Kind |
---|---|---|---|
2012-188003 | Aug 2012 | JP | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/JP2013/072599 | 8/23/2013 | WO | 00 |