JP4333119B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a double-sided display type liquid crystal display device.
[0002]
[Prior art]
For example, as a double-sided display type liquid crystal display device used for a portable device having a double-sided display function such as a cellular phone, two liquid crystal display elements are placed in a back-to-back state with their display surfaces facing in opposite directions, There is a configuration in which surface light sources that emit illumination light are arranged toward both liquid crystal display elements (see Patent Documents 1 and 2).
[0003]
However, since the use of two liquid crystal display elements increases the cost, it is desired to perform double-sided display using one liquid crystal display element.
[0004]
Conventionally, as a liquid crystal display device that performs double-sided display using a single liquid crystal display element, the screen area of the liquid crystal display element is divided into a first screen portion and a second screen portion, and one of the screen regions is divided by the first screen portion. An image observed from the other surface side is displayed, and an image observed from the other surface side is displayed by the second screen portion (see Patent Documents 3 and 4).
[0005]
[Patent Document 1]
JP-A-10-90678
[0006]
[Patent Document 2]
Japanese Patent Laid-Open No. 2001-290445
[0007]
[Patent Document 3]
JP 2000-193946 A
[0008]
[Patent Document 4]
JP 2001-305525 A
[0009]
[Problems to be solved by the invention]
However, in the double-sided display type liquid crystal display device in which the screen area of the liquid crystal display element is divided into the first and second screen parts, the display area of the liquid crystal display element is divided into a display screen on one side and a display side on the other side. Due to the size of the display screen arranged side by side, the occupied area of the liquid crystal display device is much larger than that of the double-sided display screen, and therefore the mobile device such as a mobile phone with limited mounting space for the liquid crystal display device Can not be used.
[0010]
According to the present invention, both sides can be displayed using one liquid crystal display element, and the occupied area can be reduced, and an image observed from one side and an image observed from the other side can be displayed. It is an object of the present invention to provide a liquid crystal display device capable of performing display using illumination light from a surface light source and display using external light that is light of an external environment.
[0011]
[Means for Solving the Problems]
In the liquid crystal display device of the present invention, a liquid crystal layer is provided between the front substrate and the rear substrate that are arranged to face each other, and at least one electrode is provided on one of the opposing inner surfaces of the front substrate and the rear substrate. A plurality of electrodes forming a plurality of pixels arranged in a matrix by a region facing the at least one electrode are provided on the inner surface, and front and rear polarizing plates are respectively provided on the outer surfaces of the front substrate and the rear substrate. A liquid crystal display element configured to control transmission of light incident on the plurality of pixels from the front side and the rear side by an electric field applied between the electrodes of the plurality of pixels, and one end face of the light from the light emitting element. Is formed as an incident end face to which light is incident, one of the two plate surfaces is a flat emission surface from which light is emitted, and the other plate surface is formed by arranging a plurality of elongated prism portions closely parallel to each other on the plate surface, The incident end A light guide plate made of a reflecting surface and the transparent plate is emitted from the exit surface to the inner surface reflecting light incident from And a rectangular bar-like elongated transparent material having a length corresponding to the incident end face of the light guide plate, one side surface of which forms an elongated emitting surface that emits light, and the elongated emitting surface of the elongated transparent material; One of the two intersecting end faces is an incident end face on which light is incident, and the light incident from the incident end face on the other side facing the elongated outgoing face is normal to the elongated outgoing face on one side of the light guide member. A reflective surface formed of a plurality of prism portions parallel to each other and arranged in parallel with each other on the other side surface so as to reflect the inner surface toward the direction in which the angle with respect to the light beam decreases. , A light guide member disposed so that the elongated exit surface faces the incident end surface of the light guide plate, and a λ / 2 phase difference disposed between the incident end surface of the light guide plate and the elongated exit surface of the light guide member A light emitting element disposed on a side of the plate and the light guide member If, by the composed, The liquid crystal display element is disposed on the front side and the rear side of the liquid crystal display element that emits illumination light toward the entire display area in which the plurality of pixels are arranged and transmits light incident from the front side and the rear side, respectively. Two surface light sources, wherein the two surface light sources indicate the length direction of the elongated prism portion formed on the reflection surface of each light guide plate, the front side or the rear side adjacent to each surface light source. It is characterized by being disposed substantially parallel to the transmission axis of the polarizing plate.
[0012]
The liquid crystal display device emits illumination light from a rear side light source disposed behind the liquid crystal display element toward the entire display area of the liquid crystal display element, and transmits each of the plurality of pixels of the liquid crystal display element. Then, the light emitted to the front side of the liquid crystal display element is transmitted through a front side light source disposed on the front side of the liquid crystal display element and emitted to the front side, thereby displaying an image observed from the front side. Illumination light is emitted from the side light source toward the entire display area of the liquid crystal display element, and the light transmitted through the plurality of pixels of the liquid crystal display element and emitted to the rear side of the liquid crystal display element is converted into the rear side surface. By transmitting the light source and emitting it to the rear side, an image observed from the rear side is displayed.
[0013]
That is, the liquid crystal display device emits illumination light from the rear side light source toward the entire display area of the liquid crystal display element, thereby displaying an image observed from the front side by transmissive display using the illumination light. In addition, by emitting illumination light from the front side light source toward the entire display area of the liquid crystal display element, an image observed from the rear side is displayed by transmissive display using the illumination light. According to this liquid crystal display device, both the image observed from the front side which is the one surface side and the image observed from the rear side which is the other surface side are displayed on the display area of the liquid crystal display element. Therefore, the display area of the liquid crystal display element may be a size corresponding to one of the front and rear display screens.
[0014]
Therefore, according to this liquid crystal display device, both sides can be displayed using one liquid crystal display element and the occupied area can be reduced.
[0015]
In addition, the liquid crystal display device includes the front and rear surface light sources, One end surface is an incident end surface on which light from the light emitting element is incident, one of the two plate surfaces is a flat emission surface from which light is emitted, and the other plate surface is provided with a plurality of elongated prism portions on the plate surface. A light guide plate made of a transparent plate formed as a reflection surface that is formed in parallel and densely arranged and reflects the light incident from the incident end surface to emit from the output surface, and the length direction of the elongated prism portion is The illumination light is emitted toward the entire display area that is arranged substantially parallel to the transmission axis of the front or rear polarizing plate adjacent to each surface light source and in which the plurality of pixels of the liquid crystal display element are arranged. In addition, in order to transmit the light incident from the front side and the rear side, strong light can be emitted from the two surface light sources, External light (external environment light) incident from the rear side is transmitted through the rear side light source and incident on the liquid crystal display element, and light transmitted through the plurality of pixels and emitted to the front side of the liquid crystal display element is transmitted. Outside light that is emitted to the front side of the front side light source and is incident from the front side is transmitted through the front side light source to enter the liquid crystal display element, and is transmitted through the plurality of pixels to be behind the liquid crystal display element. Can be emitted to the front side of the rear side light source.
[0016]
Therefore, according to this liquid crystal display device, an image observed from the front side is displayed by a transmissive display using illumination light from the rear side light source and a transmissive display using external light incident from the rear side. The image observed from the rear side can be displayed by transmissive display using illumination light from the front side light source and transmissive display using external light incident from the front side.
[0017]
As described above, in the liquid crystal display device of the present invention, the plurality of pixels of the liquid crystal display element are respectively provided on the front side and the rear side of the liquid crystal display element that controls transmission of light incident on the plurality of pixels from the front side and the rear side. By arranging a front side light source and a rear side light source that emit illumination light toward the entire display area to be arranged and transmit light incident from the front side and the rear side, both sides are formed using one liquid crystal display element. In addition to reducing the occupied area, an image observed from one surface side (front side) and an image observed from the other surface side (rear side) are respectively used with illumination light from the surface light source. The display can be performed by display and display using external light which is light of the external environment.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
1 to 5 show a first embodiment of the present invention. FIG. 1 is an exploded perspective view of a liquid crystal display device, and FIG. 2 is a sectional view of a part of the liquid crystal display device.
[0019]
As shown in FIGS. 1 and 2, the liquid crystal display device of this embodiment includes one liquid crystal display element 1 and two surface light sources 20a disposed on the front side and the rear side of the liquid crystal display element 1, respectively. 20b.
[0020]
As shown in FIG. 2, the liquid crystal display element 1 has a liquid crystal layer 4 between a transparent substrate 2 on the front side (upper side in the figure) and a transparent substrate 3 on the rear side (lower side in the figure). A plurality of pixels A that are provided and are arranged in a matrix form with at least one transparent electrode 5 on one of the opposed inner surfaces of the front substrate 2 and the rear substrate 3 and on the other inner surface by a region facing the at least one electrode 5. A plurality of transparent electrodes 6 are provided, and front and rear polarizing plates 12 and 13 are disposed on the outer surfaces of the front substrate and the rear substrate, respectively, and the electrodes of the pixels A An image is displayed by controlling transmission of light incident on the plurality of pixels A from the front side and the rear side by an electric field applied between 5 and 6.
[0021]
The liquid crystal display element 1 is of an active matrix type. The electrode 5 provided on the inner surface of the front substrate 2 is a single film-like counter electrode, and the electrode 6 provided on the inner surface of the rear substrate 3 is These are a plurality of pixel electrodes arranged in a matrix in the row direction and the column direction.
[0022]
The plurality of pixel electrodes 6 are respectively connected to a plurality of TFTs (thin film transistors) 7 provided on the inner surface of the rear substrate 3 so as to correspond to the pixel electrodes 6, respectively. It is connected to a gate wiring and a data wiring (not shown) provided on the inner surface of the rear substrate 3.
[0023]
In addition, the liquid crystal display element 1 includes a plurality of color filters 8R, 8G, and 8B corresponding to the plurality of pixels A, for example, red, green, and blue. 8G and 8B are formed on one of the substrates, for example, the inner surface of the front substrate 2 so as to correspond to the entire area of each pixel A, and the counter electrode 5 is formed on the color filters 8R, 8G, and 8B. Has been.
[0024]
Further, alignment films 9 and 10 are provided on the inner surfaces of the front substrate 2 and the rear substrate 3 of the liquid crystal display element 1 so as to cover the electrodes 5 and 6, respectively.
[0025]
The front substrate 2 and the rear substrate 3 are joined together via a frame-shaped sealing material 11 (see FIG. 1) surrounding a display area in which the plurality of pixels A are arranged in a matrix, and the front substrate 2 A liquid crystal layer 4 is provided in a region surrounded by the frame-shaped sealing material 11 between the rear substrate 3 and the rear substrate 3.
[0026]
The liquid crystal molecules of the liquid crystal layer 4 have an alignment direction in the vicinity of the front and rear substrates 2 and 3 defined by the alignment films 9 and 10 and are aligned in a predetermined initial alignment state between the substrates 2 and 3. .
[0027]
The front and rear polarizing plates 12 and 13 each have an absorption axis (not shown) and transmission axes 12a and 13a in directions orthogonal to each other, and two of the two linearly polarized lights of incident light orthogonal to each other. The absorbing polarizing plate absorbs one polarization component having a vibration plane parallel to the absorption axis and transmits the other polarization component having a vibration plane parallel to the transmission axes 12a and 13a.
[0028]
The liquid crystal display element 1 of this embodiment is a normally white mode TN (twisted nematic) type liquid crystal display element, and the liquid crystal molecules of the liquid crystal layer 4 are substantially 90 between the front and rear substrates 2 and 3. The front absorption polarizing plates 12 and 13 are arranged so that their transmission axes 12a and 13a are substantially orthogonal to each other.
[0029]
Further, the liquid crystal display element 1 is disposed between the front substrate 2 and the front polarizing plate 12 and between the rear substrate 3 and the rear polarizing plate 13 in order to improve display contrast and viewing angle. And a light scattering layer (hereinafter referred to as a scattering layer) 16 disposed between the front substrate 2 and the front retardation plate 14.
[0030]
On the other hand, the surface light sources 20a and 20b disposed on the front side (front side of the front polarizing plate 12) and the rear side (rear side of the rear polarizing plate 13) of the liquid crystal display element 1 are respectively a plurality of the liquid crystal display elements 1. The illumination light is emitted toward the entire display area where the pixels A are arranged, and the light incident from the front side and the rear side is transmitted.
[0031]
3 and 4 are a plan view and a side view of the surface light sources 20a and 20b, and FIG. 5 is a schematic diagram showing a linearly polarized light component of light emitted from the light guide member, the phase difference plate, and the light guide plate of the surface light sources 20a and 20b. FIG.
[0032]
As shown in FIGS. 3 and 4, the surface light sources 20 a and 20 b include a light guide plate 21, a light guide member 26 disposed on the side of the light guide plate 21, and the light guide plate 21 and the light guide member 26. And a phase difference plate 31 disposed between the light guide member 26 and one light emitting element 33 disposed on the side of the light guide member 26.
[0033]
The light guide plate 21 is made of a transparent plate such as an acrylic resin plate having an area facing the entire display area of the liquid crystal display element 1, and one end surface thereof forms an incident end surface 22 on which light is incident. Then, one of the two plate surfaces of the transparent plate reflects the light emitted from the flat surface 23 that emits the light guided to the transparent plate, and the other plate surface reflects the light incident from the incident end surface 22 to the inner surface. A reflection surface 24 that is emitted from the emission surface 23 is formed.
[0034]
The reflection surface 24 of the light guide plate 21 is densely arranged in parallel over the entire area of the other plate surface of the light guide plate 21, and light incident from the incident end surface 22 of the light guide plate 21 is used as a method of the emission surface 23. It consists of a plurality of prism portions 25 that are internally reflected toward the direction in which the angle with respect to the line decreases.
[0035]
The plurality of prism portions 25 are elongated prism portions having a trapezoidal cross-sectional shape that is parallel to the incident end face 22 of the light guide plate 21 and has a length extending over the entire width of the light guide plate 21. Of the two side surfaces, the side surface on the incident end surface 22 side is formed as an acute angle surface substantially perpendicular to the exit surface 23, and the other side surface is in the direction of the incident end surface 22 toward the outer surface side of the reflecting surface 24. Are formed on an inclined surface inclined at an angle of 30 to 60 degrees (preferably about 45 degrees) with respect to the emission surface 23, and a top surface portion between these side surfaces (steep angle surface and inclined surface) is emitted. It is formed on a flat surface parallel to the surface 23.
[0036]
In FIG. 4, the plurality of prism portions 25 are greatly exaggerated, but these prism portions 25 are formed at a pitch smaller than the pixel pitch of the liquid crystal display element 1.
[0037]
That is, the light guide plate 21 guides the light incident from the incident end face 22 and emits the light from the output face 23. The light incident on the light guide plate 21 from the incident end face 22 is indicated by an arrow in FIG. As shown, any one of the plurality of elongated prism portions 25 on the reflecting surface 24 that travels straight in the light guide plate 21 or is internally reflected by total reflection at the interface with the outside air (air) at the exit surface 23. Is incident on the inclined surface, and is internally reflected toward the direction in which the angle with respect to the normal of the exit surface 23 becomes smaller due to total reflection at the interface with the outside air, and exits from the exit surface 23.
[0038]
On the other hand, the light guide member 26 disposed on the side of the light guide plate 21 is made of a rectangular bar-like elongated transparent material (for example, acrylic resin material) having a length corresponding to the incident end face 22 of the light guide plate 21. One side surface of the elongated transparent material forms an elongated emission surface 28, and one of two end surfaces intersecting the elongated emission surface 28 of the elongated transparent material defines the incident end surface 27 on which light is incident. The other side surface facing the emission surface 28 forms a reflection surface 29 that reflects the light incident from the incident end surface 27 on the inner surface and emits the light from the elongated emission surface 28.
[0039]
The reflection surface 29 on the other side surface of the light guide member 26 is formed in parallel with each other closely in the entire area of the other side surface, and allows light incident from the incident end surface 27 of the light guide member 26 to be a part of the light guide member 26. It consists of a plurality of prism portions 30 that internally reflect toward the direction in which the angle with respect to the normal line of the elongated outgoing surface 28 on the side surface becomes smaller.
[0040]
The plurality of prism portions 30 are elongated prism portions that are parallel to the incident end face 27 of the light guide member 26 and have a length that covers the entire width of the other side surface of the light guide member 26 and have a triangular shape. Of the both side surfaces of the prism portion 30, the side surface on the incident end surface 27 side is formed as an acute angle surface substantially perpendicular to the elongated outgoing surface 28, and the other side surface is on the outer surface side of the reflecting surface 29. In the direction of the incident end face 27, it is formed on an inclined surface inclined at an angle of 30 to 60 degrees (preferably about 45 degrees) with respect to the elongated outgoing face 28.
[0041]
Although the plurality of prism portions 30 are greatly exaggerated in FIG. 3, these prism portions 30 are formed at a pitch that is approximately the same as the pitch of the elongated prism portions 25 on the exit surface 23 of the light guide plate 21. Has been.
[0042]
That is, the light guide member 26 guides the light incident from the incident end surface 27 and emits the light from one elongated outgoing surface 28. The light incident on the light guide member 26 from the incident end surface 27 is As indicated by the arrows in FIG. 4, the plurality of elongated prisms on the reflecting surface 24 travel straight inside the light guide member 26 or are internally reflected by total reflection at the interface with the outside air at the elongated light exit surface 28. The light is incident on any inclined surface of the portion 30, and is internally reflected toward the direction in which the angle with respect to the normal line of the elongated exit surface 28 becomes smaller due to total reflection at the interface with the outside air on the inclined surface, and the elongated exit surface The light is emitted from the entire area 28 with a uniform intensity distribution.
[0043]
The light guide member 26 has the elongated outgoing surface 28 opposed to the incident end surface 22 of the light guide plate 21, and the elongated outgoing surface 28 of the light guide member 26 and the incident end surface 22 of the light guide plate 21 are mutually connected. They are arranged in parallel.
[0044]
In this embodiment, light that has passed through the reflection surface 24 and leaked to the rear side of the light guide member 26 is returned to the rear side of the reflection surface 24 of the light guide member 26. A reflector 32 is arranged.
[0045]
The phase difference plate 31 disposed between the light guide plate 21 and the light guide member 26 is a λ / 2 phase difference plate that gives a half-wave phase difference between ordinary light and abnormal light of transmitted light. The polarization plane of the linearly polarized light component of the light emitted from the elongated light exit surface 28 of the light guide member 26 is substantially rotated by 90 degrees and is incident on the incident end face 22 of the light guide plate 21.
[0046]
The λ / 2 phase difference plate 31 has an elongated shape corresponding to the entire area of the incident end face 22 of the light guide plate 21 and the elongated exit face 28 of the light guide member 26, and the incident end face 22 of the light guide plate 21. One surface is affixed to the incident end surface 22 of the light guide plate 21 with a transparent adhesive, and the other surface is the elongated output surface of the light guide member 26. 28 is attached with a transparent adhesive.
[0047]
The light emitting element 33 arranged to face the incident end face 27 of the light guide member 26 is a solid light emitting element that emits white light composed of an LED (light emitting diode) or the like, for example, a red LED and a green LED. A blue LED is molded with a transparent resin, and white light in which red, green, and blue light emitted from these LEDs are mixed is emitted.
[0048]
The surface light sources 20a and 20b cause the light emitted from the solid-state light emitting element 33 to enter the light guide member 26 from the incident end surface 27, and the light is on the side opposite to the elongated light emission surface 28 of the light guide member 26. By reflecting the inner surface of the light guide member 26 toward the incident end surface 22 of the light guide plate 21 with a uniform intensity distribution after being internally reflected by the reflecting surface 24, the incident end surface thereof is caused to the light guide plate 21. 22, light having a uniform intensity distribution is incident from the entire area of 22, and the light is internally reflected by the emission surface 23 of the light guide plate 21 to be emitted from the entire area of the emission surface 23 of the light guide plate 21. According to the surface light sources 20a and 20b, light having a uniform intensity distribution can be emitted from the entire emission surface 23 of the light guide plate 21 with a small number of light emitting elements.
[0049]
In addition, the surface light sources 20 a and 20 b arrange light emitted from the elongated light exit surface 28 of the light guide member 26 between the incident end surface 22 of the light guide plate 21 and the elongated exit surface 28 of the light guide member 26. The λ / 2 phase difference plate 31 rotates the polarization plane of the linearly polarized light component of the light substantially 90 degrees so as to be incident on the incident end face 22 of the light guide plate 21. 26 is incident from the incident end face 27 and is internally reflected by the reflecting surface 24 on the other side of the light guide member 26, and is emitted from the elongated exit face 28 of the light guide member 26 to the light guide plate 21. The high-intensity linearly polarized light component of the light incident from the light source is internally reflected with high reflection intensity by the light exit surface 23 of the light guide plate 21, and light with sufficient intensity is emitted from the light exit surface 23 of the light guide plate 21. Can do.
[0050]
That is, as described above, the light guide plate 21 enters from the incident end face 22 and travels straight in the light guide plate 21 or is reflected from the inner surface by the output surface 23 and incident on the output surface 23. The inner surface is reflected by the surface 23 and is emitted from the emission surface 23. Since the reflection intensity by the emission surface 23 varies depending on the linearly polarized light component included in the light, the incident light beam to the reflection surface 24 and the reflected light beam are The linearly polarized light component (hereinafter referred to as “S wave”) that vibrates in the direction perpendicular to the plane to be included is internally reflected at a higher intensity than the linearly polarized light component (hereinafter referred to as “P wave”) that vibrates in the plane.
[0051]
Further, as described above, the light guide member 26 is incident from the incident end surface 27 and travels straight in the light guide member 26 or is internally reflected by one elongated outgoing surface 28 and reflected from the other side surface. The light incident on the light 24 is internally reflected by the reflecting surface 24 and is emitted from the elongated light emitting surface 28. The reflection intensity by the reflecting surface 24 varies depending on the linearly polarized light component included in the light, and the light is incident on the reflecting surface 24. The S-wave of the linearly polarized component that vibrates in the direction perpendicular to the plane containing the incident light and the reflected ray thereof is internally reflected at a higher intensity than the P-wave of the linearly polarized component that vibrates in the plane.
[0052]
Therefore, the light emitted from the elongated light exit surface 28 of the light guide member 26 has a higher intensity of the polarization component of the S wave than the polarization component of the P wave.
[0053]
And since the output surface 23 of the light guide plate 21 and the reflective surface 24 of the light guide member 26 are arranged at positions that intersect each other at 90 degrees, the light emitted from the elongated output surface 28 of the light guide member 26 Is incident on the light guide plate 21 as it is, the P wave having a low reflection intensity reflected by the reflection surface 24 of the light guide member 26 out of the light is reflected on the emission surface 23 of the light guide plate 21. A high-intensity S-wave incident as a high-intensity S-wave and reflected by the reflection surface 24 of the light guide member 26 is incident on the exit surface 23 of the light-guide plate 21 as a low-reflection intensity P-wave. The intensity of light emitted from the emission surface 23 of the light guide plate 21 is low.
[0054]
On the other hand, in the surface light sources 20a and 20b, the λ / 2 phase difference plate 31 is disposed between the incident end face 22 of the light guide plate 21 and the elongated light exit surface 28 of the light guide member 26. As shown in FIG. 5, the S wave S1 and the P wave P1 emitted from the elongated light exit surface 28 of the light guide member 26 are rotated by 90 degrees on the polarization plane by the λ / 2 phase difference plate 31, and the light guide plate 21 Incident from the incident end face 22.
[0055]
For this reason, of the light emitted from the elongated light exit surface 28 of the light guide member 26, the high intensity S wave S <b> 1 is reflected on the light exit surface 23 of the light guide plate 21 with the S wave S <b> 2 having high reflection intensity by the light exit surface 23. The P wave having a low intensity is incident on the emission surface 23 of the light guide plate 21 as a P wave having a low reflection intensity by the emission surface 23.
[0056]
Therefore, according to the surface light sources 20 a and 20 b, light having a high polarization intensity of light emitted from the elongated light exit surface 28 of the light guide member 26 is reflected by the light exit surface 23 of the light guide plate 21 with high reflection intensity. The light can be reflected from the inner surface, and therefore, light with sufficient intensity can be emitted from the emission surface 23 of the light guide plate 21.
[0057]
Thus, in the surface light sources 20a and 20b, one end surface of the transparent plate forms an incident end surface 22 on which light is incident, and one of the two plate surfaces of the transparent plate is guided through the transparent plate. A light guide plate that forms an emission surface 23 for reflecting the light incident from the incident end surface 22 on the other plate surface and emitting it from the emission surface 23, and one side surface of the elongated transparent material. In addition to forming an elongated exit surface 28 for emitting light, an incident end surface 27 on which one of two end faces intersecting the elongated exit surface 28 of the elongated transparent material is incident is opposed to the elongated exit surface 28. The side surface is formed with a reflection surface 24 for reflecting the light incident from the incident end surface 27 to be emitted from the elongated exit surface 28, and the elongated exit surface 28 is opposed to the incident end surface 22 of the light guide plate 21. The arranged light guide member 26 and the light guide plate 1 is arranged between the incident end face 22 and the elongate exit surface 28 of the light guide member 26, and the polarization plane of the linearly polarized light component of the light emitted from the elongate exit surface 28 of the light guide member 26 is substantially 90 degrees. The phase difference plate 31 is rotated and incident on the incident end face 22 of the light guide plate 21, and the solid light emitting element 33 is disposed to face the incident end face 27 of the light guide member 26. With the number of light emitting elements, light having a uniform intensity distribution and sufficient intensity can be emitted from the entire emission surface 23 of the light guide plate 21.
[0058]
Since the surface light sources 20a and 20b of this embodiment are provided with one solid-state light emitting element 33 made of an LED or the like as a light emitting element, the cost can be reduced and the number of consumed electrodes can be reduced.
[0059]
Further, since the solid-state light emitting element 33 can change the light emission intensity by controlling the driving voltage, the intensity of the light emitted from the emission surface 23 of the light guide plate 21 can be arbitrarily adjusted.
[0060]
In addition, the surface light sources 20a and 20b use the reflecting surface 24 on the other side surface of the light guide member 26 and the light incident from the incident end surface 27 of the light guide member 26 on the elongated outgoing surface 28 of the light guide member 26. Since it is formed by a plurality of prism portions 30 that are internally reflected in a direction in which the angle with respect to the line decreases, the light emitted from the elongated light exit surface 28 of the light guide member 26 is incident on the light incident end face 22 on the light guide plate 21. The light is incident from the vicinity of the direction perpendicular to the light, and the light is evenly distributed over the entire area of the light guide plate 21 to emit light having a more uniform intensity distribution from the entire area of the emission surface 23 of the light guide plate 21. it can.
[0061]
Furthermore, the surface light sources 20a and 20b are configured such that the angle of the light incident from the incident end surface 22 of the light guide plate 21 with respect to the normal line of the light exit surface 23 of the light guide plate 21 is small. Are formed by a plurality of prism portions 25 that are internally reflected toward the direction in which the light is emitted from the emission surface 23 of the light guide plate 21 in the direction of the front luminance (the direction near the normal line of the emission surface 23 of the light guide plate 21). Can be emitted.
[0062]
The front surface light source 20a makes the light exit surface 23 of the light guide plate 21 face the front surface of the liquid crystal display element 1 (the front surface of the front polarizing plate 12) and the light emitted from the light exit surface 23 of the light guide plate 21. Among them, the direction parallel to the polarization plane of the strong S wave S2, that is, the length direction of the plurality of elongated prism portions 25 on the exit surface 23 of the light guide plate 21, is transmitted through the front polarizing plate 12 of the liquid crystal display element 1. The rear surface light source 20b is arranged substantially parallel to the shaft 12a, and the light exit surface 23 of the light guide plate 21 faces the rear surface of the liquid crystal display element 1 (the rear surface of the rear polarizing plate 13). At the same time, the direction parallel to the polarization plane of the high-intensity S-wave S2 out of the light exiting from the exit surface 23 of the light guide plate 21 (the length direction of the plurality of elongated prism portions 25 on the exit surface 23 of the light guide plate 21). For the rear side of the liquid crystal display element 1 Transmission axis 13a substantially in the parallel plate 13 is disposed.
[0063]
This liquid crystal display device emits illumination light toward the entire display area of the liquid crystal display element 1 from the rear side light source 20b disposed on the rear side of the liquid crystal display element 1 out of the two surface light sources 20a and 20b. The light emitted through the plurality of pixels A of the liquid crystal display element 1 and emitted to the front side of the liquid crystal display element 1 is transmitted through the front side light source 20a disposed on the front side of the liquid crystal display element 1 and the front side thereof. The image observed from the front side is displayed, and the illumination light is emitted from the front side light source 20a toward the entire display area of the liquid crystal display element 1, whereby a plurality of pixels of the liquid crystal display element 1 are displayed. Light transmitted through A and emitted to the rear side of the liquid crystal display element 1 is transmitted through the rear side light source 20b and emitted to the rear side, thereby displaying an image observed from the rear side.
[0064]
The light emitted from the exit surface 23 of the light guide plate 21 of each of the surface light sources 20a and 20b has a polarization plane parallel to the length direction of the plurality of elongated prism portions 25 on the exit surface 23 of the light guide plate 21. In this liquid crystal display device, although the polarization intensity of the S wave S2 is high and the polarization intensity of the P wave P2 orthogonal thereto is weak, the front side light source 20a is used to transmit the light emitted from the emission surface 23 of the light guide plate 21. Among them, the direction parallel to the polarization plane of the high-intensity S wave S2 is arranged substantially parallel to the transmission axis 12a of the front polarizing plate 12 of the liquid crystal display element 1, and the rear side light source 20b is disposed on the light guide plate 21. Of the light emitted from the light exit surface 23, the direction parallel to the polarization plane of the high-intensity S wave S 2 is arranged substantially parallel to the transmission axis 13 a of the rear polarizing plate 13 of the liquid crystal display element 1. Therefore, the light guide of the front side light source 20a The S wave S2 having high intensity of light emitted from the emission surface 23 of the light 21 is transmitted through the front polarizing plate 12 of the liquid crystal display element 1 and is incident on the liquid crystal layer 4, and the light guide plate 21 of the rear side light source 20b. The S wave S <b> 2 having high intensity of light emitted from the emission surface 23 can be transmitted through the rear polarizing plate 13 of the liquid crystal display element 1 and incident on the liquid crystal layer 4.
[0065]
First, display using illumination light from the rear side light source 20b will be described. Illumination light emitted from the rear side light source 20b toward the entire display area of the liquid crystal display element 1 is indicated by an arrow in FIG. In this way, the light enters the liquid crystal display element 1 from the rear side.
[0066]
Light incident on the liquid crystal display element 1 from the rear side thereof is converted into linearly polarized light parallel to the transmission axis 13 a by the rear polarizing plate 13, and further passes through the rear retardation plate 15 and enters the liquid crystal layer 4. While passing through the liquid crystal layer 4, the liquid crystal layer 4 receives a birefringence action according to the alignment state of the liquid crystal molecules which is changed by the electric field applied between the electrodes 5 and 6 of each pixel A.
[0067]
The light transmitted through the liquid crystal layer 4 is colored by the color filters 8R, 8G, and 8B corresponding to the respective pixels A to be colored light of red, green, or blue, and the light is scattered by the scattering layer 16, Further, the light passes through the front retardation plate 14 and enters the front polarizing plate 12. Among the light, the polarization component parallel to the transmission axis 12 a of the front polarizing plate 12 passes through the front polarizing plate 12 and is The light is emitted to the front side of the liquid crystal display element 1, further transmitted through the light guide plate 21 of the front side light source 20 a and emitted to the front side, and the polarized light component parallel to the absorption axis of the front side polarizing plate 12 is absorbed by the front side polarizing plate 12. And an image observed from the front side is displayed.
[0068]
Next, a description will be given of display using illumination light from the front side light source 20a. Illumination light emitted from the front side light source 20a toward the entire display area of the liquid crystal display element 1 is indicated by an arrow in FIG. As shown, it enters the liquid crystal display element 1 from its front side.
[0069]
The light incident on the liquid crystal display element 1 from the front side is converted into linearly polarized light parallel to the transmission axis 12 a by the front polarizing plate 12, further transmitted through the front retardation plate 14, and scattered by the scattering layer 16. Colored by the color filters 8R, 8G, and 8B corresponding to each pixel A, and enters the liquid crystal layer 4 as colored light of red, green, or blue.
[0070]
The light incident on the liquid crystal layer 4 undergoes a birefringence action according to the alignment state of the liquid crystal molecules that changes due to the electric field applied between the electrodes 5 and 6 of each pixel A while passing through the liquid crystal layer 4. The light passes through the rear retardation plate 15 and enters the rear polarizing plate 13, and the polarized light component parallel to the transmission axis 13 a of the rear polarizing plate 13 is the rear polarized light. The light passes through the plate 13 and is emitted to the rear side of the liquid crystal display element 1. Further, the light is transmitted through the light guide plate 21 of the rear side light source 20 b and emitted to the rear side, and is parallel to the absorption axis of the rear polarizing plate 13. The polarized component is absorbed by the rear polarizing plate 13 and an image observed from the rear side is displayed.
[0071]
In this embodiment, since the liquid crystal display element 1 is in a normally white mode, an image observed from the front side and an image observed from the rear side are included in the plurality of pixels A of the liquid crystal display element 1. The light emitted from the non-electric field pixel (the pixel in which the liquid crystal molecules are in the initial alignment state) to which no electric field is applied between the electrodes 5 and 6 is transmitted through the front and rear polarizing plates 12 and 13 to be emitted red. The light is displayed in green or blue, and the output from an electric field application pixel to which an electric field is applied between the electrodes 5 and 6 so that liquid crystal molecules rise and align substantially perpendicular to the surfaces of the substrates 2 and 3 is applied. This is a color image in which the incident light is absorbed by the polarizing plates 12 and 13 and a black dark display is obtained.
[0072]
In other words, the liquid crystal display device emits illumination light from the rear side light source 20b toward the entire display area of the liquid crystal display element 1, whereby an image observed from the front side by transmissive display using the illumination light. By displaying the illumination light from the front side light source 20a toward the entire display area of the liquid crystal display element 1, an image observed from the rear side is displayed by transmissive display using the illumination light. Is.
[0073]
According to this liquid crystal display device, both the image observed from the front side which is the one surface side and the image observed from the rear side which is the other surface side are displayed in the entire display area of the liquid crystal display element 1. Therefore, the display area of the liquid crystal display element 1 may have a size corresponding to one of the front and rear display screens.
[0074]
Therefore, according to this liquid crystal display device, both sides can be displayed using one liquid crystal display element 1 and the occupied area can be reduced.
[0075]
Further, as described above, the liquid crystal display device includes the front and rear side light sources 20a and 20b that emit light having a uniform intensity distribution and sufficient intensity from the entire area of the emission surface 23 of the light guide plate 21. Of the light emitted from the exit surface 23 of the light guide plate 21, the direction parallel to the vibration surface of the high-intensity S wave S <b> 2 is substantially aligned with the transmission axis 12 a of the front polarizing plate 12 of the liquid crystal display element 1. The rear side light source 20b is arranged in parallel, and the direction parallel to the vibration surface of the high-intensity S wave S2 out of the light emitted from the emission surface 23 of the light guide plate 21 is set to the rear polarization of the liquid crystal display element 1. Since the plate 13 is disposed substantially parallel to the transmission axis 13a, the liquid crystal display element generates an S wave S2 having a high intensity of light emitted from the emission surface 23 of the light guide plate 21 of the surface light sources 20a and 20b. 1 front polarizing plate 12 and rear polarization By transmitting plate 13 to be incident on the liquid crystal layer 4, the liquid crystal display device 1, bright, yet it is possible to display a high quality image without uneven brightness.
[0076]
In addition, in this liquid crystal display device, the front side light source 20a and the rear side light source 20b transmit the light incident from the front side and the rear side, respectively, so that the light enters from the rear side as shown by the broken line in FIG. External light (external environment light) is transmitted through the rear side light source 20b and incident on the liquid crystal display element 1, and the light transmitted through the plurality of pixels A and emitted to the front side of the liquid crystal display element 1 is Outside light that is emitted to the front side of the front side light source 20a and that is incident from the front side is transmitted through the front side light source 20a to be incident on the liquid crystal display element 1, and is transmitted through the plurality of pixels A to the liquid crystal display element. 1 can be emitted to the front side of the rear side light source 20b.
[0077]
Therefore, according to this liquid crystal display device, an image observed from the front side is displayed by transmissive display using illumination light from the rear side light source 20b and transmissive display using external light incident from the rear side. At the same time, the image observed from the rear side can be displayed by transmissive display using illumination light from the front side light source 20a and transmissive display using external light incident from the front side.
[0078]
In the case of display using external light, when the intensity of incident external light is insufficient and a display with sufficient brightness cannot be obtained, an image observed from the front side is transmitted from the rear side light source 20b. Display by illuminating the illumination light with the intensity to compensate for the lack of intensity, and display the image observed from the rear side by emitting the illumination light with the intensity to compensate for the lack of the intensity of the external light from the front side light source 20a. It is only necessary to use the surface light sources 20a and 20b as auxiliary light sources in the display using external light in this way, and a display with sufficient brightness can be obtained.
[0079]
As described above, the liquid crystal display device includes a plurality of pixels of the liquid crystal display element 1 respectively on the front side and the rear side of the liquid crystal display element 1 that controls transmission of light incident on the plurality of pixels A from the front side and the rear side. Since the front side light source 20a and the rear side light source 20b that emit illumination light toward the entire display area where A is arranged and transmit light incident from the front side and the rear side are arranged, one liquid crystal The display element 1 is used for both-sided display, the area occupied is reduced, and an image observed from one surface side (front side) and an image observed from the other surface side (rear side) are respectively displayed on the surface light source. The display using the illumination light from 20a and 20b and the display using the external light which is the light of the external environment can be displayed.
[0080]
In the liquid crystal display device of the above embodiment, the display contrast of the liquid crystal display element 1 is displayed between the front substrate 2 and the front polarizing plate 12 and between the rear substrate 3 and the rear polarizing plate 13, respectively. In addition, the retardation plates 14 and 15 for improving the viewing angle are disposed, and the scattering layer 16 is disposed between the front substrate 2 and the front retardation plate 14. In addition, it is possible to emit light scattered by the scattering layer 16 and having a uniform luminance distribution, so that both the image observed from the front side and the image observed from the rear side can be compared with the contrast and the viewing angle. Is sufficient, and it is possible to obtain a high-quality image without uneven brightness.
[0081]
In the above embodiment, the scattering layer 16 is disposed between the front substrate 2 and the front retardation plate 14 of the liquid crystal display element 1, and the scattering layer 16 includes the front polarizing plate 12 and the front polarizing plate 12. You may arrange | position between the phase difference plates 14. FIG.
[0082]
In addition, the front and rear light sources 20a and 20b of the liquid crystal display device of the above embodiment guide the light incident from the incident end surface 27 of the light guide member 26 through the reflection surface 24 on the other side of the light guide member 26. The one side surface of the member 26 is formed by a plurality of prism portions 30 that are internally reflected in a direction in which the angle with respect to the normal line of the elongated outgoing surface 28 becomes smaller. For example, the light guide member 26 may be a continuous inclined surface inclined in a direction closer to the elongated emission surface 28 from the incident end surface 27 side toward the other end side.
[0083]
Further, the surface light sources 20a and 20b are configured such that the light incident on the light exit surface 23 of the light guide plate 21 and the light incident from the incident end surface 22 of the light guide plate 21 are reduced in angle with respect to the normal line of the light exit surface 23 of the light guide plate 21. The light exit surface 23 of the light guide plate 21 is formed on the light exit surface 23 from the incident end surface 22 side toward the other end side of the light guide plate 21, for example. It is good also as a continuous inclined surface inclined in the near direction.
[0084]
In addition, the surface light sources 20a and 20b are configured such that one solid light emitting element 33 is disposed so as to face the incident end surface 27 of the light guide member 26, and the area of the incident end surface 27 of the light guide member 26 is the same as that described above. If it is larger than the solid light emitting element 33, a plurality of solid light emitting elements 33 may be arranged facing the incident end face 27 of the light guide member 26.
[0085]
The surface light sources 20a and 20b are provided with a light guide member 26 in which one end surface of the light guide plate 21 is formed on the incident end surface 22 and opposite to the incident end surface 22 and the one end surface is formed on the incident end surface 27. The solid light emitting element 33 is disposed so as to oppose the incident end face 27 of the light guide member 26. Both end faces of the light guide member 26 are formed on the incident end face 27, and both incident end faces 27 are formed on the both end face 27. The solid light emitting elements 33 may be disposed so as to be opposed to each other, and both end faces of the light guide plate 21 are formed on the incident end faces 22 respectively, and both the incident end faces 22 are opposed to the λ / 2 phase difference plates. 31 and the light guide member 26 may be disposed, and the solid light emitting elements 33 may be disposed to face the incident end surfaces 27 of the light guide members 26.
[0086]
Further, the surface light sources 20a and 20b emit illumination light toward the entire display area in which the plurality of pixels A of the liquid crystal display element 1 are arranged, and transmit light incident from the front side and the rear side. For example, the light guide member 26 may be omitted, and a light emitting element composed of a straight cold cathode tube or the like may be disposed so as to face the incident end face 22 of the light guide plate 21.
[0087]
Further, in the above embodiment, the front side light source 20 a has a direction parallel to the vibration surface of the high-intensity S wave S <b> 2 out of the light emitted from the emission surface 23 of the light guide plate 21. 12 is arranged substantially parallel to the transmission axis 12a, and the rear side light source 20b has a direction parallel to the vibration surface of the strong S wave S2 out of the light emitted from the emission surface 23 of the light guide plate 21. Although the liquid crystal display element 1 is disposed substantially parallel to the transmission axis 13a of the rear polarizing plate 13, the front side light source 20a and the rear side light source 20b have the incident end face 22 of the light guide plate 21 respectively. You may arrange | position toward the same direction.
[0088]
FIG. 6 is a side view of a liquid crystal display device according to a second embodiment of the present invention. The liquid crystal display device according to this embodiment has one of front and rear surface light sources 20a and 26a, for example, a rear side light source 20b. The light plate 21 is arranged so that the direction parallel to the vibration surface of the high-intensity S wave S2 out of the light emitted from the emission surface 23 is substantially parallel to the transmission axis 12a of the front polarizing plate 12 of the liquid crystal display element 1. The other surface light source, that is, the light guide plate 21 of the front side light source 20a is arranged with the emission surface 23 facing the same direction as the emission surface 23 of the light guide plate 21 of the rear side light source 20b. One light guide member 26a for guiding the light from the light emitting element 33 and making it incident on the incident end surfaces 22 of both light guide plates 21 is disposed on the side of the incident end surface 22 of the light guide 21 and one end of the light guide member 26a is disposed. Facing the incident end face of the white It is obtained by placing one solid state light emitter 33 for emitting.
[0089]
In this embodiment, the light guide member 26a has one side corresponding to the incident end face 22 of the light guide plate 21 of the one surface light source 20a and the other side part corresponding to the incident end face 22 of the light guide plate 21 of the other surface light source 20b. And a rectangular bar-like elongated transparent material (for example, acrylic resin material) having a length corresponding to the incident end face 22 of the light guide plate 21, and both side portions of one side face thereof. An elongated exit surface 28 that emits light is formed, and one of the two end surfaces intersecting the elongated exit surface 28 of the elongated transparent material (the end surface on the back side of the paper in the figure) is an incident end surface on which light is incident. Both side portions of the other side surface facing the elongate exit surface 28 each form a reflecting surface 29 that reflects the light incident from the incident end surface to the inner surface and emits it from the elongate exit surface 28.
[0090]
The reflecting surfaces 29 on both sides of the other side surface of the light guide member 26 are formed in parallel with each other in close proximity to the entire reflecting surface 29 so that the light incident from the incident end surface 27 of the light guide member 26 is reflected. The light guide member 26 includes a plurality of prism portions 30 that are internally reflected toward a direction in which an angle with respect to the normal line of the elongated light exit surface 28 on both sides of one side surface of the light guide member 26 decreases.
[0091]
The light guide member 26a has one elongated light exit surface 28 among the elongated light exit surfaces 28 on both sides of one side surface to the incident end surface 22 of the light guide plate 21 of one surface light source 20a, and λ / 2 therebetween. The other elongated outgoing surface 28 is disposed opposite to the incident end surface 22 of the light guide plate 21 of the other surface light source 20b with the λ / 2 phase difference plate 31 interposed therebetween. The solid state light emitting device 33 is disposed to face the central portion of the incident end face of the light guide member 26a.
[0092]
According to the liquid crystal display device of this embodiment, the light guide plates 21 of the front and rear surface light sources 20a and 26a are arranged with their incident end faces 22 directed in the same direction, and the light from the light emitting element 33 is guided to the sides thereof. In addition, one light guide member 26a for making the light incident on the incident end faces 22 of both the light guide plates 21 is disposed, and one solid light emitting element 33 is disposed to face the incident end face of the light guide member 26a. Illumination light can be incident on the liquid crystal display element 1 from the front and rear surface light sources 20a and 26a using one solid-state light emitting element 33, respectively.
[0093]
In this liquid crystal display device, as described above, the light guide plate 21 of the rear side light source 20b has a liquid crystal display in a direction parallel to the vibration surface of the strong S wave S2 out of the light emitted from the emission surface 23. The light guide plate 21 of the front side light source 20a is disposed substantially parallel to the transmission axis 12a of the front polarizing plate 12 of the element 1, and the light emission surface 23 of the light guide plate 21 of the rear side light source 20b is aligned with the light emission plate 23 of the rear side light source 20b. Since the rear side light source 20b is arranged in the same direction, the S wave S2 having high intensity among the S wave S2 and the P wave P2 emitted from the emission surface 23 of the light guide plate 21 is emitted from the liquid crystal display element. 1 is transmitted through the front polarizing plate 12 and enters the liquid crystal layer 4. From the front side light source 20 a, the P wave having a low intensity among the S wave S 2 and the P wave P 2 emitted from the emission surface 23 of the light guide plate 21. P2 is the rear polarizing plate 13 of the liquid crystal display element 1. Spent and enters the liquid crystal layer 4.
[0094]
Therefore, in this liquid crystal display device, there is a difference in brightness between an image observed from the front side and an image observed from the rear side when displaying using the illumination light from the surface light sources 20a and 20b. The image observed from the rear side is slightly darker than the observed image.
[0095]
Therefore, in the liquid crystal display device of this embodiment, the front surface on which a bright image is observed, that is, the outer reflective surface 24 of the light guide plate 21 of the front side light source 20a is used as the main display surface, and the rear surface, that is, the light guide plate of the rear side light source 20b. 21 is preferably used as the sub display surface.
[0096]
In this embodiment, one solid light emitting element 33 is disposed so as to face the incident end face of the light guide member 26a. However, a plurality of solid light emitting elements 33 are opposed to the incident end face of the light guide member 26a. Further, both end surfaces of the light guide member 26a may be formed on the incident end surfaces, and the solid light emitting elements 33 may be disposed so as to face both the incident end surfaces.
[0097]
Furthermore, both end surfaces of the light guide plates 21 of the front and rear surface light sources are respectively formed on the incident end surfaces, the light guide members 26a are respectively disposed on both end sides of these light guide plates 21, and λ is formed between the incident end surfaces of both the light guide plates 21. / 2 A phase difference plate 31 may be interposed.
[0098]
In addition, the liquid crystal display devices of the first and second embodiments described above each include the TN type liquid crystal display element 1, but the liquid crystal display element is not limited to the TN type, and STN (Super Twisted). A nematic) type, a non-twisted homogeneous orientation type, a ferroelectric or antiferroelectric liquid crystal display element, or the like may be used.
[0099]
Further, the liquid crystal display element is not limited to a normally white mode, but may be a normally black mode, and the liquid crystal cell is not limited to an active matrix type but may be a simple matrix type.
[0100]
The liquid crystal display device is used for a double-sided display type portable device. 7 to 10 are perspective views of a double-sided display type portable device in which the liquid crystal display device is mounted.
[0101]
The portable device shown in FIG. 7 is a foldable mobile phone 40, and has a main body 41 having a keyboard 42 on the upper surface and display units 44a and 44b on two outer surfaces opposite to each other. And a lid portion 43 that is pivoted to open and close.
[0102]
The cellular phone 40 has a main display on the inner surface of the lid portion 43 (the surface facing the user of the phone when the lid portion 43 is opened) with the lid portion 43 opened as shown in FIG. Main information such as transmission destination data and sent / received mail is displayed on the part 44a, and the clock is displayed on the sub display part 44b on the outer surface of the lid part 43 with the lid part 43 closed as shown in FIG. Sub-information such as sender data and the like. The display units 44 a and 44 b on both sides are provided with display windows 45 a and 45 b on the inner surface and outer surface of the lid 43, respectively. One of the front and rear surfaces of the liquid crystal display device (the main display surface in the case of the second liquid crystal display device shown in FIG. 6) is opposed to the display window 45a on the inner surface of the lid, and the other surface (FIG. 6 in the case of the second liquid crystal display device shown in FIG. It is constructed by mounting to face the 示窓 45b.
[0103]
The cellular phone 40 drives the liquid crystal display element 1 of the liquid crystal display device so as to display an image that is reversed left and right when the lid portion 43 is opened and when the lid portion 43 is closed. Accordingly, a display drive unit is provided, and therefore, a correct image without left-right inversion can be displayed on the main display portion 44a on the inner surface of the lid portion 43 and the sub-display portion 44b on the outer surface.
[0104]
The portable device shown in FIG. 8 is a thin digital camera 50, and two external surfaces of the camera body 51 provided with an imaging lens 52, a finder 53, and the like, which are opposite to each other, that is, the rear surface shown in FIG. Display portions 44a and 44b are respectively provided at positions corresponding to each other on the back side of the (photographer side surface) and the front surface (subject side surface) shown in FIG. 8B.
[0105]
The digital camera 50 displays an image being captured and a captured image that has been captured on the main display unit 54a on the rear surface and the sub display unit 54b on the front surface. Display windows 55a and 55b are provided on the rear surface and the front surface of the main body 51, respectively, and the liquid crystal display device is placed inside the camera main body 51, and either one of the front and rear surfaces (the second liquid crystal display device shown in FIG. 6). In this case, the main display surface is opposed to the display window 55a on the rear surface of the camera body 51, and the other surface (sub display surface in the case of the second liquid crystal display device shown in FIG. It is configured by mounting it facing the front display window 55b.
[0106]
The digital camera 50 can display an image being captured or a stored image that has been captured by selecting either the main display unit 54a or the sub display unit 54b, or the main display unit 54a. It can also be displayed on both the sub display unit 54b at the same time. When either the main display unit 54a or the sub display unit 54b is selected and displayed, the liquid crystal display element 1 of the liquid crystal display device is displayed. By driving to display an image with the left and right reversed when displayed on the main display unit 54a and when displayed on the sub display unit 54b, both the display units 54a and 54b are correct without horizontal reversal. When an image is displayed and simultaneously displayed on both the main display portion 54a and the sub display portion 54b, one of both the 54a and 54b, for example, the sub display portion 54b is displayed. Image display image of the main display section 54a is horizontally reversed can be displayed.
[0107]
The portable device shown in FIG. 9 is a notebook personal computer 60, and has a main body 61 having a keyboard 62 on the upper surface and display parts 64a and 64b on two outer surfaces opposite to each other. It consists of a lid part 63 that is pivotally opened and closed.
[0108]
The notebook type personal computer 60 has a main surface on the inner surface of the lid portion 63 (a surface facing the user of the personal computer when the lid portion 63 is opened) with the lid portion 63 opened as shown in FIG. The main information is displayed on the display section 64a, and the sub information is displayed on the sub display section 64b on the outer surface of the lid section 63 with the lid section 63 closed as shown in FIG. 9B. The display portions 64a and 64b are provided with display windows 65a and 65b on the inner surface and the outer surface of the lid portion 63, respectively, and the liquid crystal display device is placed inside the lid portion 63 and either one of its front and rear surfaces (see FIG. The main display surface in the case of the second liquid crystal display device shown in FIG. 6 is opposed to the display window 65a on the inner surface of the lid, and the other display surface is the sub display surface in the case of the second liquid crystal display device shown in FIG. ) Is mounted facing the display window 65b on the outer surface of the lid. To have.
[0109]
Even in a state in which the lid 63 is closed, the notebook computer 60 partially displays a clock or an illustration on a part of the sub display 64b on the outer surface, or displays a television image on the entire sub display 64b. The liquid crystal display element 1 of the liquid crystal display device displays an image that is reversed left and right when the lid portion 63 is opened and closed. By driving in this way, it is possible to display correct images without left-right reversal on the main display portion 64a on the inner surface and the sub display portion 64b on the outer surface of the lid portion 63, respectively.
[0110]
The notebook personal computer 60 may have a configuration in which a transparent touch input panel is arranged on the rear display surface of the liquid crystal display device on the sub display portion 64b on the outer surface of the lid portion 63. Even when the lid 63 is closed, information can be input from the touch input panel and information can be displayed on the sub display unit 64b.
[0111]
The portable device shown in FIG. 10 is a video camera 70, which includes an imaging lens 72, a finder 73, and the like, and a camera body 71 having a monitor storage portion 74 formed on one side surface, and two outer surfaces opposite to each other. The monitor unit 75 includes display units 76a and 76b, and is used by being raised from the monitor storage unit 74 of the camera body 71.
[0112]
The video camera 70 displays an image being captured or a stored image that has been captured, with a main display 76a on the rear surface of the monitor unit shown in FIG. 10B and a sub-display on the front surface of the monitor unit shown in FIG. The display portions 76a and 76b on both sides of the monitor portion 75 are provided with display windows 77a and 77b on the rear surface and the front surface of the monitor portion 75, respectively. One of the front and rear surfaces of the liquid crystal display device (main display surface in the case of the second liquid crystal display device shown in FIG. 6) is opposed to the display window 77a on the rear surface of the monitor unit 75, and the other A surface (in the case of the second liquid crystal display device shown in FIG. 6, a sub display surface) is mounted so as to face the display window 77 b on the front surface of the monitor unit 75.
[0113]
The video camera 70 can display an image being captured or a captured image that has been captured by selecting either the main display portion 76a or the sub display portion 76b on both sides of the monitor portion 75. It can also be displayed on both the main display section 76a and the sub display section 76b at the same time. When either the main display section 76a or the sub display section 76b is selected and displayed, the liquid crystal display device The liquid crystal display element 1 is driven so as to display an image in which the left and right are reversed when displaying on the main display section 76a and when displaying on the sub display section 76b, so that both the display sections 76a and 76b When a correct image without left-right reversal is displayed and simultaneously displayed on both the main display portion 76a and the sub display portion 76b, one of both the 76a and 76b, for example, On the display unit 76 b, it is possible to display an image display image of the main display section 76a is horizontally reversed.
[0114]
Each of the portable devices 40, 50, 60, and 70 shown in FIGS. 7 to 10 is a device in which the liquid crystal display device mounted therein displays both sides using one liquid crystal display element 1. The area occupied by the liquid crystal display device is sufficient for approximately one of the liquid crystal display elements 1, so that the device can be miniaturized and the display on both sides can be displayed with a sufficiently large screen size. It can be manufactured at a lower cost as compared with the one mounted with a double-sided display type liquid crystal display device having two liquid crystal display elements.
[0115]
Moreover, the portable devices 40, 50, 60, and 70 display images that the liquid crystal display device is observed from the front side and the rear side, respectively, using illumination light from the surface light sources 20a and 20b and display using outside light. Therefore, both of the two-sided displays can be displayed by a display using illumination light from the surface light sources 20a and 20b of the liquid crystal display device and a display using outside light.
[0116]
The liquid crystal display device of the present invention can be used not only for the mobile phone 40, the digital camera 50, the notebook computer 60, and the video camera 70 described above, but also for other double-sided display type portable devices. , Two display windows are provided on the outer surfaces of the two devices opposite to each other, and the liquid crystal display device is disposed inside the two windows so that one surface of the liquid crystal display device faces one display window of the two device outer surfaces. What is necessary is just to mount facing a display window.
[0117]
【The invention's effect】
In the liquid crystal display device according to the present invention, light from the light emitting element is incident on one end face on each of the front side and the rear side of the liquid crystal display element that controls transmission of light incident on a plurality of pixels from the front side and the rear side. An incident end surface, one of the two plate surfaces is a flat emission surface from which light is emitted, and the other plate surface is formed by arranging a plurality of elongated prism portions closely parallel to each other on the plate surface; A light guide plate made of a transparent plate that is a reflection surface for reflecting incident light from the inner surface to be emitted from the emission surface. And a rectangular bar-like elongated transparent material having a length corresponding to the incident end face of the light guide plate, one side surface of which forms an elongated emitting surface that emits light, and the elongated emitting surface of the elongated transparent material; One of the two intersecting end faces is an incident end face on which light is incident, and the light incident from the incident end face on the other side facing the elongated outgoing face is normal to the elongated outgoing face on one side of the light guide member. A reflective surface formed of a plurality of prism portions parallel to each other and arranged in parallel with each other on the other side surface so as to reflect the inner surface toward the direction in which the angle with respect to the light beam decreases. , A light guide member disposed so that the elongated exit surface faces the incident end surface of the light guide plate, and a λ / 2 phase difference disposed between the incident end surface of the light guide plate and the elongated exit surface of the light guide member A light emitting element disposed on a side of the plate and the light guide member When provided with a configured surface light source by, The liquid crystal display element is configured such that a length direction of the elongated prism portion formed on the reflection surface of each light guide plate is substantially parallel to a transmission axis of a front or rear polarizing plate adjacent to each surface light source. Since a front side light source and a rear side light source that emit illumination light toward the entire display area where a plurality of pixels are arranged and transmit light incident from the front side and the rear side are arranged, one The surface light source displays a double-sided display using a liquid crystal display element and reduces an occupied area, and an image observed from one side (front side) and an image observed from the other side (rear side), respectively. Display using strong illumination light from the display and display using external light which is light from the external environment.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a part of the liquid crystal display device.
FIG. 3 is a plan view of a surface light source before and after the liquid crystal display device.
FIG. 4 is a side view of the surface light source.
FIG. 5 is a schematic diagram showing a linearly polarized light component of light emitted from a light guide member, a phase difference plate, and a light guide plate of the surface light source.
FIG. 6 is a side view of a liquid crystal display device according to a second embodiment of the present invention.
FIG. 7 is a perspective view of a mobile phone on which the liquid crystal display device of the present invention is mounted.
FIG. 8 is a perspective view of a digital camera on which the liquid crystal display device of the present invention is mounted.
FIG. 9 is a perspective view of a notebook personal computer on which the liquid crystal display device of the present invention is mounted.
FIG. 10 is a perspective view of a video camera in which the liquid crystal display device of the present invention is mounted.
[Explanation of symbols]
1 ... Liquid crystal display element
2,3 ... Board
4 ... Liquid crystal layer
5, 6 ... Electrode
7 ... TFT
8R, 8G, 8B ... Color filters
A ... Pixel
12, 13 ... Polarizing plate
14, 15 ... retardation plate
16 ... Light scattering layer
20a, 20b ... surface light source

Claims (1)

A liquid crystal layer is provided between the front substrate and the rear substrate disposed to face each other, and at least one electrode is provided on one of the opposing inner surfaces of the front substrate and the rear substrate, and the at least one electrode is provided on the other inner surface. A plurality of electrodes for forming a plurality of pixels arranged in a matrix by opposing regions are provided, and front and rear polarizing plates are disposed on the outer surfaces of the front substrate and the rear substrate, respectively. A liquid crystal display element that controls transmission of light incident on the plurality of pixels from the front side and the rear side by an electric field applied between the electrodes of the pixel;
One end surface is an incident end surface on which light from the light emitting element is incident, one of the two plate surfaces is a flat emission surface from which light is emitted, and the other plate surface is provided with a plurality of elongated prism portions on the plate surface. A light guide plate formed of a transparent plate formed as a reflection surface that is formed in parallel and densely arranged, and reflects light incident from the incident end surface to emit from the output surface, and a length corresponding to the incident end surface of the light guide plate The side surface of the elongated transparent material forms an elongated light emitting surface that emits light, and light is incident on one of two end surfaces that intersect the elongated light emitting surface of the elongated transparent material. The light incident from the incident end surface on the other side facing the elongated outgoing surface as the incident end surface is reflected internally toward the direction in which the angle with respect to the normal of the elongated outgoing surface on one side of the light guide member decreases. Close to each other on the other side. A light guide member that is formed in parallel to each other and has a reflecting surface composed of a plurality of prism portions parallel to the incident end surface of the light guide member, and is disposed so that the elongated emission surface faces the incident end surface of the light guide plate; A λ / 2 phase difference plate disposed between the incident end surface of the light guide plate and the elongated light exit surface of the light guide member, and a light emitting element disposed on the side of the light guide member, The liquid crystal display element is disposed on the front side and the rear side of the liquid crystal display element that emits illumination light toward the entire display area in which the plurality of pixels are arranged and transmits light incident from the front side and the rear side, respectively. Two surface light sources,
With
In the two surface light sources, the length direction of the elongated prism portion formed on the reflection surface of each light guide plate is substantially parallel to the transmission axis of the front or rear polarizing plate adjacent to each surface light source. A liquid crystal display device characterized by being arranged.

Images