JP2004126196A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device that is more convenient to use, thinner and lighter and is produced at a lower cost than a conventional liquid crystal display device which has a configuration to display screens on both sides such as the case of a portable telephone terminal or the like where a set of liquid crystal display devices are assembled in a back to back manner making the thickness and the weight greater as a whole and resulting in poor operability and utilization as a product. <P>SOLUTION: A pair of opposing substrates 19 and 19' are arranged on both sides of a central substrate 11 which is provided with reflection layers 12 and 12' on both surfaces, and liquid crystal members 23 and 23' are arranged between the substrates 11, 19 and 19'. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device in which a pair of opposing substrates are arranged on both sides of a single central substrate having reflection layers formed on both surfaces, and a liquid crystal capable of displaying a screen from either side of the opposing substrate. It relates to a display device.
[0002]
[Prior art]
As a current color liquid crystal display device, an active matrix type color liquid crystal display device is predominant because there is no crosstalk between adjacent pixels and a good display image can be realized. As shown in FIG. 5, this active matrix type color liquid crystal display device has a thin film transistor using amorphous silicon as a semiconductor layer on a substrate 51 made of a transparent glass material having a thickness of about 0.5 to 1 mm. (TFT) 52 is provided, and a plurality of transparent pixel electrodes 53 connected to the TFT 52 are provided. Then, a blue, green, and red color filter 54 made of an acrylic material or the like is formed so as to cover at least a part of the TFT 52, and an alignment film made of polyimide or the like is formed on the surface of the color filter 54. It has an array substrate 56 on which 55 is formed.
[0003]
A counter substrate 57 disposed opposite to the array substrate 56 has a substrate 58 similarly formed of a transparent glass material having a thickness of about 0.5 to 1 mm. A transparent opposing electrode 59 made of ITO or the like is provided on the opposing surface opposite to the above, and an alignment film 60 made of polyimide or the like is provided on the opposing electrode 59.
[0004]
In addition, a silver paste (not shown) or the like is disposed around the screen as an electrode transfer material for applying a voltage from above the array substrate 56 to the counter substrate 57, and the electrode transfer material causes a gap between the array substrate 56 and the counter substrate 57. The connection is made electrically.
[0005]
The space between the array substrate 56 and the opposing substrate 57 is defined by a plurality of spacers 61 interposed between the two substrates 56 and 57 at substantially equal intervals. Are bonded via a sealing material 62 made of a heat- or ultraviolet-curing acrylic or epoxy adhesive, and a liquid crystal member 63 is sealed in the gap. The liquid crystal panel 65 is configured by disposing the reference numeral 64 on the surface of the substrate 51 or the like.
[0006]
A polarizing plate 66 is attached to both outer surfaces of the liquid crystal panel 65 with an adhesive, and a backlight or a reflecting plate (not shown) is provided outside the polarizing plate 66 on the array substrate 56 side as necessary. ) Are arranged to constitute a color liquid crystal display device.
[0007]
In the color liquid crystal display device configured as described above, for example, the backlight serving as a light source is turned on, and the TFT 52 is driven to control the switching of the pixel electrode 53 so that the pixel electrode 53 is supplied to the counter electrode 59 facing the voltage. A predetermined color image is displayed by controlling the liquid crystal member 63 on each pixel electrode 53 according to a potential difference from the applied voltage to perform a role of an optical shutter. This color liquid crystal display device can display a color image with sufficient display quality such as luminance and contrast even in this configuration.
[0008]
Such a color liquid crystal display device can be configured to be lightweight and thin, and has characteristics such as low power consumption, so that it can be used for displaying information terminals, clocks, and television receivers. It is used as a monitor, especially in a foldable mobile phone terminal, which is arranged on both sides of its opening / closing lid. For example, clock information is displayed on an external color liquid crystal display device exposed to the outside with the lid closed. The color liquid crystal display device on the inner surface exposed with the lid open is configured to display various information such as incoming mail information, outgoing mail information, and telephone number.
[0009]
As described above, a color liquid crystal display device that displays necessary information that differs depending on whether the lid is opened or closed is extremely convenient for the user. Independent color liquid crystal display device is incorporated.
[0010]
Therefore, the thickness and weight of the entire pair of color liquid crystal display devices to be incorporated are simply required to be twice that of a single color liquid crystal display device, and the thickness and weight of the device are only increased. In addition, an increase in cost was inevitable.
[0011]
In addition, this color liquid crystal display device has no flexibility because both substrates 51 and 58 are made of glass material having a thickness of about 0.5 to 1 mm, and thus are exclusively used for color televisions. It is used as a solid-state display device such as a John receiver, a color terminal display, or a monitor screen of a mobile phone terminal. In the solidified color liquid crystal display device, an attempt to give flexibility to the color liquid crystal display device itself has been promoted in order to specify a use purpose.
[0012]
In order to realize flexibility in this liquid crystal display device, it is essential that both substrates 51 and 58 have flexibility. Therefore, the glass substrate is formed into an ultrathin plate having a thickness of 0.1 mm or less, and the substrate is applied to the array substrate 56 and the counter substrate 57 of the color liquid crystal display device so that the weight is reduced, and the substrate is not broken even when bent. It can be configured as a flexible color liquid crystal display device with enhanced strength so that it will be developed in new fields such as e-books, electronic organizers, and various forms of advertising media with curved surfaces in the future Could be possible.
[0013]
[Problems to be solved by the invention]
As described above, in order to configure the screen of the color liquid crystal display device so that the screen can be viewed from both sides, a pair of independent color liquid crystal display devices are combined back to back to determine whether the device is a single color liquid crystal display device. Therefore, the thickness of the color liquid crystal display device built in the device becomes thicker and heavier, and there is room for further improvement, particularly when adopted in a portable device. Therefore, development of more convenient equipment has been desired.
[0014]
Further, even if a flexible substrate is employed, not only the same problem is inherent, but also an intermediate page portion having a display surface on both sides such as an electronic book or an electronic organizer is employed. In such a case, the thickness of the page is also increased, and as a result, only a heavy product may be manufactured, which may result in poor usability.
[0015]
The present invention has been made in view of such a problem, and opposing substrates are disposed on both sides of a central substrate provided with a reflective layer on both sides, and a liquid crystal member is interposed between the central substrate and the opposing substrate. An object of the present invention is to provide a liquid crystal display device capable of visually recognizing a screen from both sides, which can be formed thin and lightweight.
[0016]
[Means for Solving the Problems]
The present invention provides a central substrate provided with one electrode formed on both surfaces via a reflective layer, a pair of opposed substrates arranged on both sides opposite to the central substrate and provided with the other electrode on the opposed surface, A liquid crystal display device is constituted by a plurality of spacers each defining a gap between the pair of opposing substrates and the central substrate, and a liquid crystal member sandwiched between the opposing central substrate and the opposing substrate. The display screen can be selectively viewed from the substrate side.
[0017]
With this configuration, the central substrate can be used as a common substrate, and the thickness of the entire device can be reduced, and the weight of the device can be reduced. It is possible to obtain a liquid crystal display device suitable for use in a product that is used by overlapping a plurality of sheets.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0019]
As shown in FIG. 1, a color liquid crystal display device according to the present invention has a reflection member or a reflection member on both main surfaces of a central substrate 11 made of a transparent glass material having a thickness of about 0.5 to 1 mm. The reflection layers 12, 12 'made of electrodes are formed, and electrode wiring and TFTs 13, 13' are provided on the surfaces of the reflection layers 12, 12 'by making use of fine techniques such as film formation and patterning. The TFTs 13 and 13 'and the electrode wiring are configured as follows, for example.
[0020]
That is, after depositing a molybdenum-tungsten (MoW) film on the reflective layers 12 and 12 ′ surfaces formed on both main surfaces of the central substrate 11 by using a sputtering method and then patterning, the TFTs 13 and 13 ′ are formed. And a scanning line for supplying a scanning signal. A gate insulating film made of silicon oxide or silicon nitride is provided on the reflective layers 12 and 12 'so as to cover the gate electrodes and the scanning lines, and a CVD is provided on the surface of the gate insulating film on which the gate electrodes are arranged. After depositing an amorphous silicon film by using the method, patterning is performed, and semiconductor layers constituting the TFTs 13 and 13 'are arranged. Further, on this semiconductor layer, molybdenum (Mo) / aluminum (Al) / molybdenum (Mo) are sequentially deposited and patterned to form a source electrode, a drain electrode, and a TFT 13, 13 'having a three-layer structure. It is configured to form a signal line for supplying a video signal.
[0021]
The TFTs 13 and 13 'are formed by depositing ITO or the like to a thickness of 1500.degree. By sputtering and patterning by photolithography to form transparent pixel electrodes 14 and 14' which constitute one of the electrodes. One ends of the pixel electrodes 14 and 14 'are connected to source / drain paths of the TFTs 13 and 13'. The TFTs 13 and 13 'are arranged at intersections of signal lines and scanning lines arranged in a matrix. These pixel electrodes 14 and 14 ′ are provided with color filters 15 and 15 ′, each of which is color-coded red (R), blue (B) and green (G) so as to cover at least a part thereof. It is provided in a shape.
[0022]
For example, when the first color is composed of red, the color filters 15 and 15 ′ are formed by first applying an ultraviolet-curing acrylic resin resist in which a red pigment is dispersed using a spinner to the reflection layers 12 and 12 on the central substrate 11. 'Is applied uniformly over the entire surface, and then exposed to ultraviolet light having a wavelength of 365 nm and an intensity of 100 mJ / cm ² through a photomask pattern in which light is applied to a portion to be colored red. I do. This photomask pattern has a stripe-shaped pattern portion corresponding to the first color and a square-shaped pattern portion for a stacked spacer. Thereafter, development is performed with a 1% aqueous solution of KOH for 20 seconds to form a 3.2 μm-thick red colored layer on the pattern portion. Subsequently, a green coloring layer and a blue coloring layer are formed in the same manner.
[0023]
Next, a plurality of columnar spacers 16 and 16 ′ having one end fixed to the color filters 15 and 15 ′ and the other end as a free end are arranged at predetermined portions located in the non-display areas of the color filters 15 and 15 ′. Is done. The locations where the spacers 16 and 16 'are located are provided between pixel patterns other than the display area of the pixel cells at least one per one or a plurality of pixel cells. In addition, frame layers 17 and 17 ′ made of a black light-shielding film are provided by a photolithography method on the outer peripheral portion of the display region that is the outer peripheral portion of the pixel electrodes 14 and 14 ′ or the color filters 15 and 15 ′. . Further, on the color filters 15, 15 ', alignment films 18, 18' formed by applying polyimide or the like to a thickness of 600 ° are arranged.
[0024]
On the other hand, a pair of opposed substrates 19 and 19 ′ are arranged so as to face the central substrate 11. The opposite substrates 19 and 19 ′ are also made of a transparent glass material having a plate thickness of about 0.5 to 1 mm, and the other electrode made of ITO or the like is formed on the opposite surface facing the central substrate 11. The transparent opposing electrodes 20, 20 'and the alignment films 21, 21' made of polyimide or the like and having a thickness of 600 ° are sequentially laminated on the opposing electrodes 20, 20 '.
[0025]
The opposing substrates 19, 19 'and the central substrate 11 are maintained at a predetermined gap by the spacers 16, 16', and the periphery except for the injection port is formed by sealing materials 22, 22 'made of, for example, a thermosetting epoxy adhesive. Electrode transfer material for applying a voltage from the central substrate 11 to the opposing substrates 19 and 19 'is fixed by heating and bonding the portions to the electrode transfer electrodes (not shown) around the seal materials 22 and 22'. Formed on top. Liquid crystal members 23 and 23 'made of, for example, a fluorine-based liquid crystal compound are injected into the gaps, and then the injection ports are sealed with an ultraviolet curable resin to form liquid crystal panels 24 and 24', respectively. . Further, polarizers 25, 25 'are bonded and fixed to the outer surfaces of the pair of opposed substrates 19, 19' of the liquid crystal panels 24, 24 ', respectively, to constitute a color liquid crystal display device.
[0026]
When the color liquid crystal display device is configured in this manner, the liquid crystal panel 24 is driven by supplying a predetermined driving voltage from, for example, a driving circuit (not shown) to the TFT 13 or the counter electrode 20 on one liquid crystal panel 24 side. It is possible to display a predetermined image as a reflection type. Conversely, by supplying a predetermined driving voltage to the TFT 13 ′ and the counter electrode 20 ′ on the liquid crystal panel 24 ′ side by a switch or the like, the liquid crystal panel 24 ′ side can be driven, and similarly, the liquid crystal panel 24 ′ can be driven. Can be displayed as a reflection type.
[0027]
As described above, the color liquid crystal display device 26 including the double-sided liquid crystal panels 24 and 24 'provided with the liquid crystal members 23 and 23' on both sides of the central substrate 11 with the reflection layers 12 and 12 'interposed therebetween, for example, as shown in FIG. In addition, it can be used as a display panel of a mobile phone terminal. The telephone terminal includes a terminal body 32 provided with an operation input button 31 and the like, and a lid body rotatably held at one end so as to be openable and closable on the terminal body 32 so as to selectively cover the operation input button 31. It is composed of a part 33. The color liquid crystal display device 26 is attached to the lid 33 so that the display portion is exposed on both the front and back surfaces. A switch 34 for selecting which of the liquid crystal panels 24 and 24 ′ is to be driven and a supply driving voltage thereof is disposed in the terminal main body 32. The switch 34 is switched so as to drive the liquid crystal panel 24 when the lid 33 is closed and to drive the liquid crystal panel 24 'when opened.
[0028]
In the mobile phone terminal configured as described above, when the liquid crystal panel 24 is driven, as shown in FIG. 3, external light indicated by an arrow A incident from the counter substrate 19 side of the liquid crystal panel 24 is applied to the liquid crystal panel. The light is reflected by the reflection layer 12 according to the light shutter operation of the member 23, and is recognized as a color image by the user. When the liquid crystal panel 24 'is driven, external light indicated by an arrow A' incident from the counter substrate 19 'of the liquid crystal panel 24' is reflected by the reflective layer 12 in response to the light shutter operation of the liquid crystal member 23 '. And is recognized by the user as a color image.
[0029]
In this way, it is possible to function as a reflection type liquid crystal display device capable of displaying both sides using external light. However, as shown in FIG. It is also possible to arrange the lights 35, 35 '. That is, the front lights 35, 35 'are made of a light source unit 36, 36', and a transparent material connected to the light source units 36, 36 'and disposed so as to cover the liquid crystal panels 24, 24'. Light guide plates 37 and 37 '.
[0030]
With this configuration, when the front light 35 on the image display side is turned on, for example, the light emitted from the light source unit 36 is reflected in the light guide plate 37 and The light enters the panel 24, is reflected by the reflective layer 12 according to the optical shutter operation of the liquid crystal member 23, and reaches the user side. Therefore, an image is displayed by both lights A and B in combination with the external light A, so that a bright screen can be displayed. Of course, when sufficient brightness can be obtained with only the external light A, the front light 35 does not need to be turned on. Similarly, when displaying on the liquid crystal panel 24 'side, the front light 35' may be turned on.
[0031]
As described above, in a case where the color liquid crystal display device is used by opening and closing back and forth according to opening and closing of the lid, such as a mobile phone terminal, the liquid crystal panels 24 and 24 ′ sandwich the central substrate 11. Therefore, it is possible to cope only by changing the driving start point of the liquid crystal panels 24 and 24 ', so that the manufacturing process can be simplified.
[0032]
In the color liquid crystal display device having the above-described configuration, the case where the color liquid crystal display device is formed in a non-flexible solid used by opening and closing in the front-rear direction has been described. When the color liquid crystal display device is used, it is assumed that the color liquid crystal display device itself is curved due to its usage form. In such a case, the central substrate 11 and the opposing substrates 19, 19 'themselves are formed so as to have flexibility, so that the color liquid crystal display device has flexibility so as to be able to bend. May be more convenient.
[0033]
When the color liquid crystal display device has flexibility as described above, a glass substrate having an initial thickness of about 0.7 mm is prepared as the central substrate 11 and the opposing substrates 19 and 19 '. The central substrate 11 is formed before the reflection layers 12, 12 'are formed, and the opposing substrates 19, 19' are formed at the stage where the sealing materials 22, 22 'are formed before the liquid crystal members 23, 23' are injected. The surface of each of the substrates 11, 19, 19 'is polished to a thickness of about 0.1 mm by mechanical polishing, chemical polishing, or a combination of both. It is formed so as to have flexibility. Reinforcement is performed by attaching a flexible reinforcing plate (not shown) made of a transparent resin plate or the like for preventing damage to the polished outer surfaces of the substrates 11, 19, 19 '. Thus, the entire color liquid crystal display device 26 can have flexibility. At this time, the reinforcing plate of the central substrate 11 can be shared by the reflective layers 12, 12 '.
[0034]
By making the color liquid crystal display device 26 itself flexible as described above, it is suitable for use in an electronic book, an electronic organizer, or the like, and can display two pages of the product. In this case, when the present invention is applied to a product that opens and closes left and right, it is difficult to form the liquid crystal panels 24 and 24 ′ symmetrically with the center substrate 11 interposed therebetween, and the liquid crystal panels 24 and 24 ′ are configured. The arrangement of the color filters 15 and 15 'needs to be formed in the arrangement order in which the liquid crystal panel 24 and the liquid crystal panel 24' are inverted by 180 degrees. I have. In addition, it is more convenient to configure the switch for display switching so that it can be selectively switched manually in the case of selection of continuous page display at the time of single-sided display or double-sided display.
[0035]
Note that the present invention is not limited to those described in the embodiments, and various applications and modifications are possible. For example, when patterning the material of the color filters 15 and 15 ′, the color filters 15 and 15 ′ may be used. If the laminated spacers 16 and 16 'are formed simultaneously with the formation of the colored layer by sequentially laminating the colored layer materials constituting the'', the manufacturing process of the spacers 16 and 16' can be simplified. Further, the spacers 16 and 16 'can be constituted by spherical spacers 16 and 16'.
[0036]
When the frame layers 17, 17 'are formed on the opposing substrates 19, 19', the spacers 16, 16 'can be formed together using the frame layers 17, 17'. If the spacers 16 and 16 'are formed using the same material as the frame layer material constituting the frame layers 17 and 17', the spacers 16 and 16 'can be simultaneously formed of the same material when the frame layers 17 and 17' are formed. It is possible to reduce the number of steps.
[0037]
Further, the color filters 15, 15 'can be configured to be provided on the opposing substrates 19, 19', or the frame layers 17, 17 'can be formed on the opposing substrates 19, 19' side. Further, the spacers 16 and 16 'are not limited to those having one end fixed to the central substrate 11, but may be fixed to the opposing substrates 19 and 19'. Further, the spacers 16 and 16 'protrude from the substrates 11, 19 and 19', respectively. It can also be arranged to be installed. Needless to say, the present invention can be applied not only to a color liquid crystal display device but also to a black and white liquid crystal display device.
[0038]
Further, the TFTs 13 and 13 'may be provided not on the central substrate 11 but on a pair of opposing substrates 19 and 19'. In this case, the reflection layers 12, 12 'provided on the central substrate 11 can also serve as the counter electrodes 20, 20'.
[0039]
【The invention's effect】
As described above, according to the present invention, a pair of liquid crystal panels is configured by arranging opposing substrates on both sides of a single central substrate provided with reflection layers on both sides and arranging liquid crystal members. Therefore, the liquid crystal display device can be formed to have a small overall thickness and a light weight, and furthermore, it is possible to reduce the material used and thereby to reduce the cost, thereby providing a highly convenient liquid crystal. A display device can be obtained.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a liquid crystal display device according to the present invention.
FIG. 2 is an explanatory diagram showing a state in which the liquid crystal display device is similarly incorporated in a mobile phone terminal.
FIG. 3 is an explanatory diagram for explaining a screen display state of the liquid crystal display device.
FIG. 4 is an explanatory diagram for explaining a screen display state of another configuration of the liquid crystal display device.
FIG. 5 is a cross-sectional view showing a conventional liquid crystal display device.
[Explanation of symbols]
11: central substrate 12, 12 ': reflective layer 14, 14': pixel electrode (one electrode)
16, 16 ': spacers 19, 19': counter substrate 20, 20 ': counter electrode (the other electrode)
23, 23 ': liquid crystal member 34: switch 35, 35': front light

Claims (4)

A central substrate provided with one electrode formed on both sides via a reflective layer,
A pair of opposing substrates disposed on both sides facing the central substrate and provided with the other electrode on the opposing surface,
A plurality of spacers respectively defining the gap between the pair of opposed substrates and the central substrate,
A liquid crystal member sandwiched between the opposed central substrate and the opposed substrate,
A liquid crystal display device, wherein a screen is selectively displayed from either side of the pair of opposing substrates. 2. The liquid crystal display device according to claim 1, wherein a front light is disposed outside each of the pair of opposed substrates. 2. The liquid crystal display device according to claim 1, wherein said pair of opposed substrates and said central substrate are each formed of a flexible substrate. 2. The liquid crystal display device according to claim 1, further comprising a switch for controlling at least an input to each of the electrodes corresponding to a viewing direction of the pair of opposed substrates.

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