This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-216392, filed on Sep. 30, 2011, the entire contents of which are incorporated herein by reference.
The embodiment discussed herein is related to a liquid crystal display device and an information terminal including the liquid crystal display device.
In recent years, liquid crystal display devices such as electronic paper have been actively developed in enterprises and universities. Applications of, for example, electronic paper to various information terminals including, first of all, electronic books and also sub-displays of mobile terminals and display units of IC cards have been proposed.
A liquid crystal display device has a structure in which a liquid crystal sandwiched between two substrates is surrounded and sealed by a sealant. When a liquid crystal display device having such a structure is produced, a vacuum injection method is used as a method of filling a display area defined by the two substrates and the sealant with a liquid crystal.
According to an aspect of the embodiment, a liquid crystal display device and an information terminal include: a first substrate; a second substrate opposite to the first substrate; a sealant provided between the first substrate and the second substrate to define a display area to be filled with a liquid crystal; and a liquid crystal injection port defined by the first substrate, the second substrate and the sealant, wherein regions where the first substrate, the second substrate and the sealant are positioned on a same plane are provided on opposite sides of the liquid crystal injection port, each of the regions where the first substrate, the second substrate and the sealant are positioned on the same plane having a length equal to 0.26e0.64Ra (mm) or more from the liquid crystal injection port, where surface roughness of the regions where the first substrate, the second substrate and the sealant are positioned on the same plane is Ra (μm).
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.
In a liquid crystal injection process in which a display area is filled with a liquid crystal through a liquid crystal injection port by the above vacuum injection method, as illustrated, for example, in
Thus, costs are preferably reduced and quality and reliability are preferably improved by preventing the liquid crystal from entering the region outside the display area.
A liquid crystal display device according to an embodiment and an information terminal including the liquid crystal display device will be described below using the drawings with reference to
The liquid crystal display device according to the present embodiment is for example, electronic paper using a cholesteric liquid crystal. The liquid crystal display device is also called a liquid crystal display apparatus or a display apparatus.
The cholesteric liquid crystal is a liquid crystal composition in which a cholesteric phase is formed and is appropriately used for a display unit of electronic paper, for example. The cholesteric liquid crystal has such superior features as semipermanent display holding properties (memory properties), clear color display properties, high contrast properties, and high resolution properties. Details thereof will be described later.
The liquid crystal display device is, as illustrated in
Among these display units, the B display unit 2 includes a pair of an upper substrate 6 and a lower substrate 7 placed opposite to each other, a blue liquid crystal layer 8 that reflects blue light in a planar state, electrodes 9 to apply a voltage to a liquid crystal, and a sealant 10 that seals the liquid crystal filled between both substrates.
The B liquid crystal layer 8 is formed by encapsulating a cholesteric liquid crystal for B adjusted to selectively reflect blue in a region (display area) 20 surrounded by the upper substrate 6, the lower substrate 7 and the sealant 10 (see
The G display unit 3 includes the pair of the upper substrate 6 and the lower substrate 7 placed opposite to each other, a green (G) liquid crystal layer 11 that reflects green light in a planar state, the electrodes 9 to apply a voltage to a liquid crystal, and the sealant 10 that seals the liquid crystal filled between both substrates.
The G liquid crystal layer 11 is formed by encapsulating a cholesteric liquid crystal for G adjusted to selectively reflect green in the region (display area) 20 surrounded by the upper substrate 6, the lower substrate 7 and the sealant 10 (see
The R display unit 4 includes the pair of the upper substrate 6 and the lower substrate 7 placed opposite to each other, a red (R) liquid crystal layer 12 that reflects red light in a planar state, the electrodes 9 to apply a voltage to a liquid crystal, and the sealant 10 that seals the liquid crystal filled between both substrates.
The R liquid crystal layer 12 is formed by encapsulating a cholesteric liquid crystal for R adjusted to selectively reflect red in the region (display area) 20 surrounded by the upper substrate 6, the lower substrate 7 and the sealant 10 (see
The upper substrate 6 and the lower substrate 7 of each of the display units 2 to 4 are substrates having translucency. A polycarbonate (PC) film substrate is used in the present embodiment. Instead of the PC substrate as a plastic film substrate, a glass substrate or a plastic film substrate of polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) may be used. In the present embodiment, each of the upper substrate 6 and the lower substrate 7 is assumed to have translucency, but the lower substrate 7 of the R display unit 4 placed in the lowest layer may be non-translucent.
The electrodes 9 of each of the display units 2 to 4 are a scanning electrode 9A and a data electrode 9B. In the present embodiment, a plurality of band-like scanning electrodes 9A extending in the left and right direction in
Though not illustrated, an alignment layer formed of, for example, polyimide resin is preferably provided on each of these scanning electrodes 9A and data electrodes 9B to control the arrangement of liquid crystal molecules.
Scanning electrode drive circuit 13 on which a scanning electrode driver IC to drive the plurality of scanning electrodes 9A of each of the display units 2 to 4 is mounted is connected to the plurality of scanning electrodes 9A. In the present embodiment, the scanning electrode drive circuit 13 includes a common scanning electrode driver IC as the scanning electrode driver IC to drive the scanning electrodes 9A of each of the display units 2 to 4. Thus, without providing a respective scanning electrode driver IC to drive each of the scanning electrodes 9A of each of the display units 2 to 4, the configuration of the scanning electrode drive circuit 13 is simplified. Incidentally, the scanning electrode driver IC may be made common when needed and a scanning electrode driver IC may be provided a respective scanning electrode driver IC to drive each of the scanning electrodes 9A of each of the display units 2 to 4.
Data electrode drive circuit 14 on which a data electrode driver IC to drive the plurality of data electrodes 9B of each of the display units 2 to 4 is mounted is connected to the plurality of data electrodes 9B. In the present embodiment, the data electrode drive circuit 14 includes a respective data electrode driver IC to drive each of the data electrodes 9B of each of the display units 2 to 4.
The scanning electrode drive circuit 13 and the data electrode drive circuit 14 output a scanning signal or a data signal to the predetermined scanning electrode 9A or data electrode 9B based on a predetermined signal output from a control circuit 15 respectively. Accordingly, a predetermined pulse voltage is applied to each of the liquid crystal layers 8, 11, 12.
The sealant 10 of each of the display units 2 to 4 is provided, as illustrated in
Though not illustrated, a spacer is provided in each of the liquid crystal layers 8, 11, 12 of each of the display units 2 to 4 to maintain the thickness, that is, to uniform the cell gap of each of the liquid crystal layers 8, 11, 12 of each of the display units 2 to 4. For example, spherical spacers made of resin or inorganic oxide may be dispersed and formed or a plurality of columnar spacers from a structure may be formed. The cell gap d of each of the liquid crystal layers 8, 11, 12 is preferably about 3 μm≦d≦about 6 μm.
Incidentally, the liquid crystal composition constituting the B, G, F liquid crystal layers 8, 11, 12 is a cholesteric liquid crystal prepared by adding a relatively large amount of several tens of wt % in content of a chiral additive (also called a chiral material) to a nematic liquid crystal mixture. In the present embodiment, the liquid crystal composition is a cholesteric liquid crystal prepared by adding about 10 to about 40 wt % of chiral material to a nematic liquid crystal mixture. The amount of addition of the chiral material is a value when the total amount of the nematic liquid crystal component and the chiral material is 100 wt %. By including a relatively large amount of chiral material in the nematic liquid crystal in this manner, nematic liquid crystal molecules can be made to a cholesteric liquid crystal in which a cholesteric phase created by nematic liquid crystal molecules being strongly twisted in a helical fashion is formed. Thus, the cholesteric liquid crystal is also called a chiral nematic liquid crystal. Various publicly-known nematic liquid crystals can be used as the nematic liquid crystal. The refractive index anisotropy (Δn) is preferably in the range of about 0.18 to about 0.24. If the refractive index anisotropy (Δn) is smaller than this range, the reflectivity in a planar state decreases. If the refractive index anisotropy (Δn) is larger than this range, the scatter reflection in a focal conic state Increases and also the viscosity increases, leading to a slower response speed. Further, the thickness of the liquid crystal is preferably about 3 μpm to about 6 μm and if the thickness is thinner than the range, the reflectivity in a planar state decreases. If the thickness is thicker than the range, the drive voltage becomes too high.
Such a cholesteric liquid crystal has bistability (memory properties), and can be in a planar state, focal conic state, or an intermediate state that these states mix, by controlling an electric field intensity applied to the liquid crystal. Then, once the cholesteric liquid crystal is in a planar state, focal conic state, or an intermediate state, the cholesteric liquid crystal can thereafter maintain the state with stability in a state without electric field.
The planar state can be obtained by, for example, applying a predetermined high voltage to between the upper and lower substrates to apply a strong electric field to the liquid crystal layer and after the liquid crystal being brought into a homeotropic state, reducing the electric field rapidly to zero. The focal conic state can be obtained by, for example, applying a predetermined voltage lower than the above high voltage to between the upper and lower substrates to apply an electric field to the liquid crystal layer and then, reducing the electric field rapidly to zero. The focal conic state can also be obtained by gradually applying a voltage from a planar state. An intermediate state between the planar state and the focal conic state can be obtained by, for example, applying a voltage lower than the voltage at which a focal conic state can be obtained to between the upper and lower substrates to apply an electric field to the liquid crystal layer and then, reducing the electric field rapidly to zero.
Next, the principle of display of the liquid crystal display device 1 using such a cholesteric liquid crystal will be described by taking the B display unit 2 as an example.
First,
As illustrated in
In the planar state, light of predetermined wavelengths in accordance with the helical pitch of liquid crystal molecules is selectively reflected by the liquid crystal layer 8. Where the average refractive index of the liquid crystal layer 8 is n and the helical pitch thereof is p, the wavelength at which the reflection is maximum is expressed as λ=n·p. Therefore, to cause the liquid crystal layer 8 of the B display unit 2 to selectively reflect blue light in a planar state, the average refractive index n and the helical pitch p are decided so as to be, for example, λ=480 nm. The average refractive index n can be adjusted by selecting the liquid crystal material and the chiral material and the helical pitch p can be adjusted by adjusting the content rate of the chiral material.
Next,
As illustrated in
In an intermediate state between the planar state and the focal conic state, the ratio of reflected light and transmitted light can be adjusted in accordance with the state thereof and thus the intensity of the reflected light can be varied.
Thus, in a cholesteric liquid crystal, the reflection amount of light can be controlled by the alignment state of liquid crystal molecules twisted in a helical fashion.
Such a cholesteric liquid crystal that selectively reflects blue light in a planar state is used for the B liquid crystal layer 8 of the B display unit 2. Similarly, a cholesteric liquid crystal that selectively reflects green light in a planar state is used for the G liquid crystal layer 11 of the G display unit 3. Further, a cholesteric liquid crystal that selectively reflects red light in a planar state is used for the R liquid crystal layer 12 of the R display unit 4. Then, by stacking the liquid crystal layers 8, 11, 12 that selectively reflect blue, green, and red lights (see
In a stacked structure of the display units 2 to 4 of B, G, R, it is preferable to make optical activity of the G liquid crystal layer 11 and that of the B, R liquid crystal layers 8, 12 in a planar state different. Accordingly, losses of reflected light can be reduced to improve brightness of the display screen of the liquid crystal display device 1.
Also in the present embodiment, the visible light absorption layer 5 is arranged on the back face side of the lower substrate 7 of the R display unit 4 and when the liquid crystal layers 8, 11, 12 of B, G, R are all in the focal conic state, transmitted light is absorbed by the visible light absorption layer 5 and black is displayed on the display screen of the liquid crystal display device 1. The visible light absorption layer 5 may be provided when needed.
The display units 2 to 4 of the liquid crystal display device 1 configured as described above can be produced as described below.
First, a plurality of scanning electrodes 9A and a plurality of data electrodes 9B are formed on the surfaces of the two substrates 6, 7 respectively (see
Next, the two substrates 6, 7 are bonded together by the sealant 10 provided in a peripheral portion of one of the substrates 6 (7) (see
Next, the display area 20 defined by the upper substrate 6, the lower substrate 7 and the sealant 10 is filled with the liquid crystal by the vacuum injection method (see
Then, after the display area 20 being filled with the liquid crystal, though not illustrated, the liquid crystal injection port 22 is sealed by a sealant.
In this manner, the display units 2 to 4 of the liquid crystal display device 1 configured as described above can be produced.
Incidentally, various examinations to prevent the liquid crystal from entering a liquid crystal unnecessary region outside the display area 20 as illustrated in
First, as illustrated in
Next, the relationship between surface roughness Ra (μm) of regions where the upper substrate 6, the lower substrate 7 and the sealant 10 are made flush with each other, that is, regions where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane, and the liquid crystal spread distance (mm) is examined.
Three liquid crystal materials of different compositions, that is, an R cholesteric liquid crystal, a G cholesteric liquid crystal, and a B cholesteric liquid crystal are used as liquid crystal materials.
A film substrate is used as the upper substrate 6 and the lower substrate 7, and the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane by simultaneously cutting the upper substrate 6, the lower substrate 7 and the sealant 10 while the upper substrate 6 and the lower substrate 7 are bonded by the sealant 10. Thus, the surface roughness Ra of the regions where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane is the surface roughness of a cut surface of the upper substrate 6, the lower substrate 7 and the sealant 10. Then, the surface roughness Ra of the regions where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane is adjusted by changing the blade used to cut the upper substrate 6, the lower substrate 7 and the sealant 10 simultaneously to the Thomson blade, ring cutters (double-edged, single-edged), or scissors.
The surface roughness Ra is the surface roughness (arithmetic average roughness) defined by JIS B0601-1994. That is, the surface roughness Ra is, as illustrated in
The measurement of the surface roughness Ra of the regions where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane is made using a laser microscope (Keyence, VK-9700). More specifically, as illustrated in
As illustrated in
As a result, the relationship illustrated in
Thus, in the present embodiment, the display units 2 to 4 of the liquid crystal display device 1 are configured as described below.
That is, in the present embodiment, the display units 2 to 4 of the liquid crystal display device 1 include, as illustrated in
More specifically, the display units 2 to 4 of the liquid crystal display device 1 are defined by the upper substrate 6, the lower substrate 7 and the sealant 10, and include a projection portion 24 having the liquid crystal injection port 22 at an end thereof. The projection portion 24 of each of the display units 2 to 4 is defined by a projection portion of the upper substrate 6, a projection portion of the lower substrate 7 opposite thereto and the sealant 10 each provided between the side portions of the projection portion of the upper substrate 6 and the side portions of the projection portion of the lower substrate 7 along the side portions of the upper substrate 6 and the lower substrate 7. The upper portion of the end of the projection portion 24 is defined by the end face of the upper substrate 6, the lower portion thereof is defined by the end face of the lower substrate 7, and each of the side portions thereof is defined by the end face of the sealant 10, and the liquid crystal injection port 22 is located on the end of the projection portion 24. In this case, the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane include side faces, where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane, of the projection portion 24, respectively. That is, each of the regions 23 includes first region defined by the side face of the projection portion 24 and second region defined by the end face other than the projection portion 24. Accordingly, the length of each of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane can be made still longer. If, for example, the display units 2 to 4 are small in size, this is effective in making the length of each of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane longer.
Accordingly, the liquid crystal can be prevented from entering a region (liquid crystal unnecessary region) 21 outside the display area 20 in the liquid crystal injection process. That is, by making the upper substrate 6, the lower substrate 7 and the sealant 10 exposed on opposite sides of the liquid crystal injection port 22 flush with each other, that is, by providing regions where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on a same plane on opposite sides of the liquid crystal injection port 22, the spread of liquid crystal during injection of the liquid crystal can be suppressed so that infiltration of the liquid crystal from opposite sides of the liquid crystal injection port 22 into the region 21 outside the display area 20 due to capillarity can be prevented. Further, by setting the length of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane on opposite sides of the liquid crystal injection port 22 from the liquid crystal injection port 22 to the above length, the length can be made longer than the liquid crystal spread distance during injection of the liquid crystal so that infiltration of the liquid crystal from opposite sides of the liquid crystal injection port 22 into the region 21 outside the display area 20 due to capillarity can reliably be prevented.
Particularly, the surface roughness Ra of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane is preferably about 8 μm or less. Accordingly, the liquid crystal spread distance during injection of the liquid crystal can be made shorter so that infiltration of the liquid crystal from opposite sides of the liquid crystal injection port 22 into the region 21 outside the display area 20 due to capillarity can reliably be prevented.
Each of the display units 2 to 4 of the liquid crystal display device 1 described above, that is, each of the display units 2 to 4 of the liquid crystal display device 1 having the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane on opposite sides of the liquid crystal injection port 22 can easily be produced by bonding the upper substrate 6 and the lower substrate 7 by the sealant 10 and then cutting the upper substrate 6, the lower substrate 7 and the sealant 10 simultaneously. Particularly, simultaneous cutting can be made easier by using a plastic film substrate as the upper substrate 6 and the lower substrate 7.
Next, a production example of the display units 2 to 4 included in the liquid crystal display device 1 configured as described above will be described.
First, IZO transparent electrodes are formed on the two polycarbonate (PC) film substrates 6, 7 cut to the size of length and width of about 12 cm×about 12 cm and patterned by etching to form the about 0.24 mm-pitch electrodes 9 in a stripe shape. In this case, the 320 electrodes 9A and 240 electrodes 9B in a stripe shape are formed on the two PC film substrates 6, 7 respectively so that a QVGA display of 320×240 dots can be made (see
Next, the two PC film substrates 6, 7 on which the electrodes 9 are formed are cleaned, and polyimide as an alignment layer is applied to a thickness of about 500 Å and baked at about 150° C. for about 1 hour.
Next, a photoresist is applied to one of the PC film substrates 6 (7), patterned by undergoing a photolithography process and baked at about 150° C. for about 120 minutes to form a structure (spacer) of about 5 μm in height.
Next, the epoxy sealant 10 is applied to a peripheral portion of the other PC film substrate 7 (6) by using a dispenser apparatus. In the present embodiment, as will be described later, since the projection portion 24 is formed, the sealant 10 is applied into a shape as illustrated in
Next, the two PC film substrates 6, 7 are bonded and heated at about 160° C. for about 1 hour while being pressed by the force of about 1 kg/cm2. Accordingly, the sealant 10 is hardened and the substrates 6, 7 are bonded via the sealant 10. At the same time, the structure is also bonded to the substrates 6, 7, forming a uniform cavity for injection of the liquid crystal.
Next, the projection portion 24 having the liquid crystal injection port 22 and the regions 23 where the PC film substrates 6, 7 and the sealant 10 are positioned on the same plane on opposite sides of the liquid crystal injection port 22 are formed. In this case, the two PC film substrates 6, 7 and the sealant 10 are cut simultaneously into a shape illustrated in
Next, the display area 20 defined by the PC film substrates 6, 7 and the sealant 10 is filled with the liquid crystal (see
Then, after the display area 20 being filled with the liquid crystal, though not illustrated, the liquid crystal injection port 22 is sealed by a sealant.
In this manner, each of the display units 2 to 4 of the liquid crystal display device 1 configured as described above can be produced.
Therefore, according to a liquid crystal display device according to the present embodiment, the liquid crystal can be prevented from entering the region 21 outside the display area 20 so that costs can advantageously be reduced and also quality and reliability can be improved.
That is, according to the present liquid crystal display device, in the liquid crystal injection process in which the display area 20 is filled with the liquid crystal by the vacuum injection method, infiltration of the liquid crystal into the region 21 outside the display area 20 that needs not be filled with the liquid crystal, that is, into the region outside the sealant 10 can be prevented. Accordingly, the cleaning process to wash out an unnecessary liquid crystal after the liquid crystal injection process can be eliminated so that lower costs can be achieved by reducing man-hours and costs. Electrodes are provided in the region 21 outside the display area 20 and if the liquid crystal infiltrates into the region 21 and remains there, corrosion of electrodes or terminals will be caused by aging, but because infiltration of the liquid crystal into the region 21 can be prevented, corrosion of electrodes or terminals caused by aging can be prevented. As a result, quality and reliability can be improved.
Incidentally, electronic paper as a liquid crystal display device according to the above embodiment can be used for information terminals such as electronic books, sub-displays of mobile terminals and display units of IC cards. In this case, as illustrated, for example, in
The present invention is not limited to configurations described in the above embodiment and a modification and can be modified in various ways without deviating from the scope of the present invention.
In the above embodiment, for example, each of the display units 2 to 4 of the liquid crystal display device 1 is configured to include the projection portion 24, but the above embodiment is not limited to such an example and, for example, as illustrated in
Also in this case, the upper portion of the liquid crystal injection port 22 is defined by the end face of the upper substrate 6, the lower portion thereof is defined by the end face of the lower substrate 7 and each of side portions thereof is defined by the end face of the sealant 10. Then, the upper substrate 6, the lower substrate 7 and the sealant 10 are exposed on opposite sides of the liquid crystal injection port 22 of the display units 2 to 4 of the liquid crystal display device 1, and the upper substrate 6, the lower substrate 7 and the sealant 10 sandwiched between the substrates 6, 7 are made flush. Then, the length of each of regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are flush with each other from the liquid crystal injection port 22 is a length of about 0.26e0.64Ra (mm) or more, where the surface roughness of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are flush is Ra (μm). That is, the upper substrate 6, the lower substrate 7 and the sealant 10 on opposite sides of the liquid crystal injection port 22 are made to be positioned on the same plane and the length of each of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane from the liquid crystal injection port 22 is set a length of about 0.26e0.64Ra (mm) or more, where the surface roughness of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane is Ra (μm). Accordingly, the liquid crystal can be prevented from entering the region 21 outside the display area 20 in the liquid crystal injection process. That is, by making the upper substrate 6, the lower substrate 7 and the sealant 10 exposed on opposite sides of the liquid crystal injection port 22 flush with each other, the spread of liquid crystal during injection of the liquid crystal can be suppressed so that infiltration of the liquid crystal from opposite sides of the liquid crystal injection port 22 into the region 21 outside the display area 20 due to capillarity can be prevented. Further, by setting the length of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane on opposite sides of the liquid crystal injection port 22 from the liquid crystal injection port 22 to the above length, the length can be made longer than the liquid crystal spread distance during injection of the liquid crystal so that infiltration of the liquid crystal from opposite sides of the liquid crystal injection port 22 into the region 21 outside the display area 20 due to capillarity can reliably be prevented. Also in this case, the surface roughness Ra of the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane is preferably about 8 μm or less. Accordingly, the liquid crystal spread distance during injection of the liquid crystal can be made shorter so that infiltration of the liquid crystal from opposite sides of the liquid crystal injection port 22 into the region 21 outside the display area 20 due to capillarity can reliably be prevented.
Each of the display units 2 to 4 of the liquid crystal display device 1 according to such a modification, that is, each of the display units 2 to 4 of the liquid crystal display device 1 having the regions 23 where the upper substrate 6, the lower substrate 7 and the sealant 10 are positioned on the same plane on opposite sides of the liquid crystal injection port 22 can easily be produced by bonding the upper substrate 6 and the lower substrate 7 by the sealant 10 and then cutting the upper substrate 6, the lower substrate 7 and the sealant 10 simultaneously. Particularly, simultaneous cutting can be made easier by using a plastic film substrate as the upper substrate 6 and the lower substrate 7.
Next, a production example of the display units 2 to 4 included in the liquid crystal display device 1 according to such a modification will be described.
First, IZO transparent electrodes are formed on the two polycarbonate (PC) film substrates 6, 7 cut to the size of length and width of about 24 cm×about 24 cm and patterned by etching to form the 0.48 mm-pitch electrodes 9 in a stripe shape. In this case, the 320 electrodes 9A and 240 electrodes 9B in a stripe shape are formed on the two PC film substrates 6, 7 respectively so that a QVGA display of 320×240 dots can be made (see
Next, the two PC film substrates 6, 7 on which the electrodes 9 are formed are cleaned, and polyimide as an alignment layer is applied to a thickness of about 500 Å and baked at about 150° C. for about 1 hour.
Next, a photoresist is applied to one of the PC film substrates 6 (7), patterned by undergoing a photolithography process and baked at about 150° C. for about 120 minutes to form a structure (spacer) of about 5 μm in height.
Next, the epoxy sealant 10 is applied to a peripheral portion of the other PC film substrate 7 (6) by using a dispenser apparatus. In the present modification, the projection portion 24 in the above embodiment is not provided and thus, the sealant 10 is applied into a shape as illustrated in
Next, the two PC film substrates 6, 7 are bonded and heated at about 160° C. for about 1 hour while being pressed by the force of about 1 kg/cm2. Accordingly, the sealant 10 is hardened and the substrates 6, 7 are bonded via the sealant 10. At the same time, the structure is also bonded to the substrates 6, 7, forming a uniform cavity for injection of the liquid crystal.
Next, the liquid crystal injection port 22 and the regions 23 where the PC film substrates 6, 7 and the sealant 10 are positioned on the same plane on opposite sides of the liquid crystal injection port 22 are formed. In this case, the two PC film substrates 6, 7 and the sealant 10 are cut simultaneously into a shape illustrated in
Next, the display area 20 defined by the PC film substrates 6, 7 and the sealant 10 is filled with the liquid crystal (see
Then, after the display area 20 being filled with the liquid crystal, though not illustrated, the liquid crystal injection port 22 is sealed by a sealant
In this manner, each of the display units 2 to 4 of the liquid crystal display device 1 according to above modification can be produced.
The above embodiment and modification are described by taking the liquid crystal display device using the cholesteric liquid crystal as an example, but are not limited to the cholesteric liquid crystal. For example, the present invention can be applied to a liquid crystal display device using other liquid crystal materials such as the nematic liquid crystal, ferroelectric liquid crystal, and anti-ferroelectric liquid crystal and a similar effect can naturally be obtained in such cases.
All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
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2011-216392 | Sep 2011 | JP | national |