JP2004102127A - Display device and portable information terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable information display device which is capable of performing both side display, is equipped with an illumination source to realize device utilization in a dark place or else, allows the thickness of a display part smaller and is suitably used for a foldable portable telephone and PDA etc. <P>SOLUTION: The display region of one display panel 20 is divided into a plurality of regions including a first display region 2a which makes one surface side of the display panel 20 a display surface and a second display region 2b which makes the other surface side of the display panel 20 an observation surface. An illumination source 10 which can illuminate both of the first display region 2a and the second display region 2b is disposed on either of the one surface side or the other surface side of the display panel 20. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display device capable of displaying images on both sides suitable for use in a foldable mobile phone, a PDA, and the like, and a portable information terminal device provided with the display device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in the field of portable information terminal devices such as mobile phones and PDAs, devices capable of displaying information such as characters, images, and videos by mounting a display device are commercially available. However, those having a reflective or transflective liquid crystal display device which is easy to see and can reduce power consumption are widely used.
In addition, among such portable information terminal devices, in particular, in the field of mobile phones, a foldable type having a large display unit and capable of being compactly stored has become widespread.
In such a foldable mobile phone, an upper housing incorporating a display device and a lower housing provided with an input keyboard and the like are usually connected by a hinge portion, and a display surface is provided in a state where the mobile phone is folded. It is designed to be stored inside.
[0003]
By the way, in the above-mentioned foldable mobile phone, the display surface is hidden inside in the foldable state. Many of them are provided with an auxiliary display on the side.
[0004]
As a structure in which the display surface is provided on the inner surface side and the outer surface side of the upper housing as described above, for example, a structure in which separate transmissive liquid crystal panels are provided for the main display portion and the auxiliary display portion (Patent Document 1 or Patent Document 2) See). In this display device, as shown in FIG. 6A, a transmissive liquid crystal panel 310e for main display and a transmissive liquid crystal panel 310h for auxiliary display are provided one by one with a backlight 310 interposed therebetween. 310e and 310h are driven by one or separate drivers.
[0005]
As another structure, for example, a structure has been proposed in which one surface of one liquid crystal panel is used as a main display portion 301e and the other surface is used as an auxiliary display portion 301h (see Patent Document 3 or Patent Document 4). In this display device, as shown in FIG. 6B, the display area of one liquid crystal panel 311 is divided into two areas, a main display area 301E and an auxiliary display area 301H, and each of the areas 301E and 301H is viewed from the viewer side. Reflecting layers 311e and 311h are provided on the back side of the liquid crystal panel 311 when viewed. This makes it possible to realize a thin and low power consumption display unit using external light reflection.
[0006]
Further, as another structure, for example, a structure in which a backlight is provided for each of a main display area and an auxiliary display area (see Patent Document 5) has been proposed. In this display device, as shown in FIG. 6C, the display area of one transmissive liquid crystal panel 312 is divided into two areas, a main display area 301E and an auxiliary display area 301H. Backlights 312e and 312h are provided on the back side of the liquid crystal panel 312 when viewed from the side. Thus, a bright display can be obtained by the backlight while the number of the liquid crystal panels 312 is one.
[0007]
[Patent Document 1]
JP 2001-290445 A [Patent Document 2]
JP 2000-338483 A [Patent Document 3]
Japanese Patent Laid-Open No. Hei 10-198291 [Patent Document 4]
JP 2000-193946 A [Patent Document 5]
JP 2001-290445 A
[Problems to be solved by the invention]
However, in the configuration shown in FIG. 6A in which the liquid crystal panels 310e and 310h are provided on both sides of the backlight 310 one by one, expensive liquid crystal panels and drivers are required for the number of display units, resulting in high cost. Further, in the configuration shown in FIG. 6B in which both the main display portion 301e and the auxiliary display portion 301h are reflection type liquid crystal display devices, it is difficult to use the device in a dark place where sufficient external light cannot be obtained, so that it can be used outdoors. It is not suitable for use in portable information terminal equipment on the premise of the use of. Further, in the configuration shown in FIG. 6C in which backlights are provided one by one on both sides of the liquid crystal panel 312, there is a problem that the thickness of the display unit is increased.
The present invention has been made in view of the above-described problems, and has a display device and a portable information terminal device that include an illumination device so that the display portion can be reduced in thickness while enabling use in a dark place or the like. The purpose is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, in the display device of the present invention, the display area of one display panel is formed by observing a first display area having a display surface on one side of the display panel, and observing another surface side of the display panel. The display panel is divided into a plurality of areas including a second display area, and both the first display area and the second display area are illuminated on either the one side or the other side of the display panel. Possible lighting means are provided.
According to this configuration, since both the first display area and the second display area are illuminated by the illuminating means provided on one surface side of the display panel, the number of components is reduced as compared with the conventional display device. As well as thinning is possible.
Note that a front light can be used as the lighting means.
[0010]
Further, the display panel may be configured as a liquid crystal panel in which the first display area is a transmissive display section or a transflective display section, and the second display area is a reflective display section or a transflective display section. Note that when the first display region is a transflective display portion and the second display region is a reflective display portion or a transflective display portion, power consumption can be reduced when the device is used outdoors in a bright outdoor environment or the like.
[0011]
Further, a portable information terminal device according to the present invention includes the above-described display device. According to this configuration, the mobile phone can have a compact structure by incorporating the thin display device as described above.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
[First Embodiment]
FIG. 1 is a sectional view showing a main part of a portable telephone as an example of a portable information terminal device according to a first embodiment of the present invention, FIG. 2 is a perspective view of a display device incorporated in the portable telephone, and FIG. Is a cross-sectional view showing a detailed configuration of the display device, and FIG. 4 is an overall configuration diagram of a portable upper terminal device. In all of the following drawings, the thickness of each component, the ratio of dimensions, and the like are appropriately changed in order to make the drawings easy to see.
[0013]
As shown in FIG. 4, in the mobile phone 1 of the present embodiment, an upper housing 1a provided with a display unit and a lower housing 1b provided with an input keyboard 1k for performing a dial operation are hinged. It is structured so as to be freely expandable by the portion 1c.
[0014]
As shown in FIG. 1, the upper housing 1a has a built-in display device 2 capable of double-sided display. On the inner surface 1d side of the upper housing 1a, a first display area 2a of the display device 2 described later is provided. A display window 1e for a main display is provided at a position corresponding to, so that various information can be displayed in a state where the upper housing 1a is expanded. A display window 1h for auxiliary display is provided at a position corresponding to a second display area 2b to be described later on the exterior surface 1g side of the upper housing 1a, and the upper housing 1a is closed to close the main display window 1e. Even if is hidden, the user can easily grasp information such as time. In order to protect the display device 2, the display windows 1e and 1h are provided with transparent protective covers 1f and 1i, respectively.
[0015]
As shown in FIGS. 2 and 3, the display device 2 includes one liquid crystal panel (display panel) 20 and a front light (illumination unit) 10 arranged on one surface side of the liquid crystal panel 20. Have been.
The liquid crystal panel 20 has a structure in which a pair of transparent substrates 21 and 22 made of glass, plastic, or the like are opposed to each other with a liquid crystal layer 23 interposed therebetween on the inner surface side by a sealing material 24. In this specification, the surface on the liquid crystal layer 23 side of each member constituting the display device is referred to as “inner surface”, and the surface on the opposite side is referred to as “outer surface”.
[0016]
On the inner surface of the second substrate 22, an organic insulating layer 28, a reflective layer 29 made of a metal film of high reflectivity such as aluminum (Al) or silver (Ag), and a color filter layer F are sequentially formed. . On the color filter layer F, a plurality of transparent electrodes 26 are formed in a stripe shape, and an alignment film made of polyimide or the like is formed so as to cover the transparent electrodes 26.
[0017]
In addition, unevenness is formed on the surface of the organic insulating layer 28 so that light incident on the reflective layer 29 is diffusely reflected. Further, a large number of minute holes 29a are formed in the reflective layer 29, and the reflective layer 29 functions as a semi-transmissive reflective layer. It is preferable to use the same member as the lead-out wiring (not shown) for the reflection layer 29 and to form it at the same time when the lead-out wiring is formed, whereby the number of steps can be reduced. Further, the reflection layer 29 is provided only in a part of the region on the organic insulating layer 28, and the region where the reflection layer 29 is formed corresponds to the second display region 2b of the present invention. The area not formed corresponds to the first display area 2a.
[0018]
On the other hand, a plurality of stripe-shaped transparent electrodes 27 are formed on the inner surface of the first substrate 21 so as to be substantially orthogonal to the transparent electrodes 26, and an alignment film made of polyimide or the like is formed so as to cover the transparent electrodes 27. .
[0019]
The alignment film formed on each of the substrates 21 and 22 is subjected to an alignment treatment such as rubbing, and the orientation control force of the alignment film causes the orientation of the liquid crystal molecules of the liquid crystal layer 23 to be reduced when no voltage is applied. 22 are twisted about 270 degrees. The transparent electrodes 26 and 27 formed on the substrates 21 and 22 are connected to a flexible printed circuit (FPC) 30, and are driven by a driving circuit 30 a attached to the FPC 30 to form a first display area 2 a and a second display area 2 b. Are both driven and controlled. Further, polarizing plates P1 and P2 are provided on the outer surface side of each of the substrates 21 and 22, and the transmission axes of the polarizing plates P1 and P2 are arranged, for example, to be orthogonal to each other.
[0020]
The front light 10 is disposed on the front surface of the liquid crystal panel 20 (on the side of the main display window 1e of the upper housing 1a), and as shown in FIGS. 2 and 3, a flat plate made of acrylic resin, polycarbonate resin, epoxy resin, or the like. A transparent light guide plate 12 and a rod-shaped light source 13 disposed on a side end surface 12a on one side of the light guide plate 12 (in FIG. 3, the left end surface side when the plate surface direction of the light guide plate 12 is the left-right direction). It is composed of
[0021]
The light source 13 is composed of a quadrangular prism-shaped light guide 13a made of an acrylic resin, a polycarbonate resin, or the like, and light emitters 13a and 13b such as white LEDs and EL elements provided at both ends in the longitudinal direction of the light guide 13a. It is configured.
A prism surface having a concave and convex groove (not shown) is formed on the surface of the side surface of the light guide 13a opposite to the light guide plate 12, and is introduced into the light guide 13a from the luminous bodies 13a and 13b. The reflected light is reflected by the prism surface and emitted to the side end surface 12a of the light guide plate 12.
[0022]
The light guide plate 12 is disposed substantially parallel to the liquid crystal panel 20, and a side end surface 12 a facing the light source 13 is a light incident surface, and an inner surface facing the liquid crystal panel 20 is an emission surface 12 b. I have. In order to make the light introduced from the incident surface 12a fall toward the emission surface 12b, a pair of slopes 14a are formed on the outer surface of the light guide plate 12 (the surface on the main display window 1e side of the upper housing 1a). , 14b are formed in a plurality of stripes at a predetermined pitch in a stripe shape, and such a wedge-shaped groove 14 forms a reflection surface 12c. The shape of the groove 14 is designed to enhance the amount of illumination light falling on the liquid crystal panel 20 and the uniformity of the illumination light within the panel surface. For example, the inclination angle of the gentle slope portion 14a with respect to the emission surface 12b is 1 °. The inclination angle of the steep slope portion 14b with respect to the emission surface 14b is set in a range of 41 ° to 45 °.
[0023]
Next, an illumination method of the display device 2 of the present embodiment will be described with reference to FIG.
First, when the front light 10 is turned on and illumination light is incident from the light source 13 on the incident surface 12a of the light guide plate 12, a part 16a of the illumination light propagates inside the light guide plate 12 by total reflection, and the reflection surface The light is reflected by the liquid crystal panel 12 toward the liquid crystal panel 20 and is emitted from the emission surface 12b toward the first display area 2a. The emitted light is modulated by the liquid crystal layer 23 and reaches the observer U1. Thus, predetermined transmissive display is performed using the illumination light of the front light 10 as a backlight.
[0024]
Further, a part 16b of the light that has propagated in the light guide plate 12 is reflected by the reflection surface 12c and emitted toward the second display area 2b of the liquid crystal panel 20. The emitted light is modulated by the liquid crystal layer 23, reflected by the reflective layer 29 of the second substrate 22, further modulated by the liquid crystal layer 23, and reaches the observer U2 on the front light 10 side. Thereby, a predetermined reflection display using the illumination light of the front light 10 is performed.
[0025]
On the other hand, when the front light 10 is not turned on, the external light 16c incident on the second display area of the liquid crystal panel 20 via the auxiliary display window 1h passes through the liquid crystal layer 23 and is reflected by the reflection layer 29 of the second substrate. And reaches the observer U2. As a result, predetermined reflection display using external light is performed.
[0026]
Therefore, according to the display device of the present embodiment, the front light 10 functions as a backlight that illuminates the liquid crystal panel 20 from the back in the first display area 2a, and illuminates the liquid crystal panel 20 from the front in the second display area. It functions as a normal front light, and the two display areas 2a and 2b can be illuminated together by one front light 10 arranged on one surface side of the liquid crystal panel 20. For this reason, in the present display device 2, the number of components can be reduced and the thickness can be reduced as compared with a conventional display device in which one illuminating means is provided on each side of the liquid crystal panel. In addition, by incorporating such a display device 2, the upper housing 1a can be made thinner and the mobile phone 1 can have a compact structure.
[0027]
[Second embodiment]
FIG. 5 is a cross-sectional view illustrating a configuration of a display device according to the second embodiment of the present invention. In addition, among the components shown in FIG. 5, the same parts as those in the first embodiment shown in FIGS. 1 to 4 are denoted by the same reference numerals, the description thereof is partially omitted, and FIG. Will be explained.
[0028]
The display device 102 of the present embodiment is built in the upper housing 1a of the mobile phone shown in FIG. 4 and can display on both the main display window 1e and the auxiliary display window 1h, as shown in FIG. , One liquid crystal panel (display panel) 200, and a front light (illumination means) 10 arranged on one surface side of the liquid crystal panel 200. The liquid crystal panel 200 has a structure in which a pair of transparent substrates 21 and 22 made of glass, plastic, or the like opposed to each other with a liquid crystal layer 23 interposed therebetween on the inner surface side with a sealing material 24.
[0029]
An organic insulating layer 28 and a color filter layer F are sequentially formed on the inner surface of the second substrate 22. On the color filter layer F, a plurality of transparent electrodes 26 are formed in a stripe shape, and an alignment film made of polyimide or the like is formed so as to cover the transparent electrodes 26. The surface of the organic insulating layer 28 is formed with irregularities, and fine holes made of a metal film of high reflectivity such as aluminum (Al) or silver (Ag) are formed in a part of the organic insulating layer 28. A porous reflective layer 29 having a large number of portions 29a is formed. The area where the reflection layer 29 is formed corresponds to the second display area 2b of the present invention.
[0030]
On the other hand, on the inner surface of the first substrate 21, an organic insulating layer 128, a reflective layer 129 made of a metal film having high reflectivity such as aluminum (Al) or silver (Ag), and an insulating layer 121 are sequentially formed. I have. A plurality of stripe-shaped transparent electrodes 127 are formed on the insulating layer 121 so as to be substantially orthogonal to the transparent electrodes 26, and an alignment film made of polyimide or the like is formed so as to cover the transparent electrodes 26. ing. Note that unevenness is formed on the surface of the organic insulating layer 128 so that light incident on the reflective layer 129 is diffusely reflected. Further, a large number of minute holes 129a are formed in the reflective layer 129, and the reflective layer 129 functions as a semi-transmissive reflective layer. Further, the reflection layer 129 on the first substrate 21 is provided in a region that does not overlap with the reflection layer 29 of the second substrate 22 in a plan view, and the region where the reflection layer 129 is formed is the first region of the present invention. It corresponds to the display area 2a.
[0031]
The alignment film formed on each of the substrates 21 and 22 is subjected to an alignment treatment such as rubbing, and the orientation control force of the alignment film causes the orientation of the liquid crystal molecules of the liquid crystal layer 23 to be reduced when no voltage is applied. 22 are twisted about 270 degrees. Further, the transparent electrodes 26 and 127 formed on the substrates 21 and 22 are connected to a flexible printed circuit (FPC) 30 in the same manner as in the first embodiment, and are driven by a driving circuit 30 a attached to the FPC 30. The first display area 2a and the second display area 2b are both driven and controlled. Further, polarizing plates P1 and P2 are provided on the outer surface side of each of the substrates 21 and 22, and the transmission axes of the polarizing plates P1 and P2 are arranged, for example, to be orthogonal to each other.
[0032]
The front light 10 is disposed on the front surface of the liquid crystal panel 200 (on the side of the main display window 1e of the upper housing 1a), similarly to the first embodiment, and the configuration is exactly the same as that of the first embodiment. Therefore, the description is omitted.
[0033]
Next, an illumination method of the display device 102 of the present embodiment will be described with reference to FIG.
First, when the front light 10 is turned on and illumination light is incident from the light source 13 on the incident surface 12a of the light guide plate 12, a part 16a of the illumination light propagates inside the light guide plate 12 by total reflection, and the reflection surface The light is reflected to the liquid crystal panel 200 side by 12c, and is emitted from the emission surface 12b toward the first display area 2a. The emitted light enters the liquid crystal layer 23 through the hole 129a of the reflection layer 129 of the first substrate 21, and is modulated by the liquid crystal layer 23 to reach the observer U1. Thus, predetermined transmissive display is performed using the illumination light of the front light 10 as a backlight.
[0034]
Further, a part 16b of the light propagated in the light guide plate 12 is reflected by the reflection surface 12c and emitted toward the second display area 2b of the liquid crystal panel 200. The emitted light is modulated by the liquid crystal layer 23, reflected by the reflective layer 29 of the second substrate 22, further modulated by the liquid crystal layer 23, and reaches the observer U2 on the front light 10 side. Thereby, a predetermined reflection display using the illumination light of the front light 10 is performed.
[0035]
On the other hand, when the front light 10 is not turned on, the external light 16d incident on the first display area 2a of the liquid crystal panel 200 through the main display window 1e passes through the liquid crystal layer 23, and then passes through the reflective layer 129 of the first substrate 21. And reaches the observer U1. External light 16c incident on the second display area of the liquid crystal panel 200 via the auxiliary display window 1h transmits through the liquid crystal layer 23, is reflected by the reflection layer 29 of the second substrate, and reaches the observer U2. . As a result, predetermined reflection display using external light is performed.
[0036]
Therefore, also in the display device of the present embodiment, the two display areas 2a and 2b can be illuminated together by one front light 10 arranged on one surface side of the liquid crystal panel 20, as in the first embodiment. For this reason, in the present display device 102, the number of components can be reduced and the thickness can be reduced as compared with the conventional display device in which one illuminating means is provided on each side of the liquid crystal panel. Further, by incorporating such a display device 102, the upper housing 1a can be made thinner and the mobile phone 1 can have a compact structure. In addition, since both the first display area 2a and the second display area 2b are configured as a transflective display section, power consumption can be reduced when used in a bright place such as outdoors.
[0037]
Note that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the spirit of the present invention.
For example, in each of the embodiments described above, the liquid crystal panels 20 and 200 have been described as STN (Super Twisted Nematic) type color liquid crystal panels, but a normal TN type liquid crystal panel is used instead of such an STN type liquid crystal panel. The liquid crystal to be used is not limited to the nematic liquid crystal, and it is of course possible to use a smectic liquid crystal or a polymer liquid crystal. When a monochrome display is performed, the color filter layer F may be omitted.
[0038]
The driving method is not limited to the simple matrix method described above, and an active matrix method may be adopted.
Further, instead of using the porous reflective layer as the reflective layer 29 formed in the second display area 2b, it is possible to use a complete reflective layer without the holes 29.
Further, the position where the front light 10 is arranged is not limited to the first substrate 21 side, but may be the second substrate 22 side.
[0039]
【The invention's effect】
As described above in detail, according to the present invention, both the first display area and the second display area are illuminated by the illuminating means provided on one surface side of the display panel, so that a conventional display device can be provided. Compared with this, the number of parts can be reduced and the thickness can be reduced.
In addition, by incorporating such a thin display device, the mobile phone can have a compact structure.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part of a mobile phone according to a first embodiment of the present invention.
FIG. 2 is a perspective view showing a configuration of a display device built in the mobile phone according to the first embodiment of the present invention.
FIG. 3 is an AA cross-sectional view showing a configuration of a display device built in the mobile phone according to the first embodiment of the present invention.
FIG. 4 is a perspective view showing an overview of the mobile phone according to the first embodiment of the present invention, FIG. 4A is a perspective view seen from the operation surface side, and FIG. 4B is a perspective view seen from the exterior surface side. is there.
FIG. 5 is a cross-sectional view illustrating a configuration of a display device built in a mobile phone according to a second embodiment of the present invention, and is a view corresponding to FIG.
6A is a diagram showing a schematic configuration of a conventional display device, FIG. 6A is a diagram showing a configuration in which a liquid crystal panel is provided on each side of a backlight, and FIG. 6B shows both a main display and an auxiliary display. FIG. 6C is a diagram illustrating a configuration of a reflection display, and FIG. 6C is a diagram illustrating a configuration in which backlights are provided on both sides of one liquid crystal panel.
[Explanation of symbols]
1 Mobile phone (morphological information terminal equipment)
2 display device 2a first display area 2b second display area 10 Front light (illumination means)
20,200 Liquid crystal panel (display panel)

Claims (4)

The display area of one display panel is divided into a plurality of areas including a first display area having a display surface on one side of the display panel and a second display area having a display surface on the other side of the display panel. And
A display device, comprising: an illuminating means that can illuminate both the first display area and the second display area on either the one surface side or the other surface side of the display panel. The display device according to claim 1, wherein the lighting unit is a front light. The liquid crystal panel, wherein the display panel is a liquid crystal panel in which the first display area is a transmissive display section or a transflective display section, and the second display area is a reflective display section or a transflective display section. 3. The display device according to 1 or 2. A portable information terminal device comprising the display device according to claim 1.

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