JP3953078B2 - Display device and electronic device - Google Patents

Description

  The present invention relates to a display device and an electronic device, and more particularly to a configuration suitable as a display device mounted on a portable electronic device.

  Generally, as a display device mounted on a portable electronic device, an electro-optical device such as a liquid crystal display device or an electroluminescence display device is used. In particular, a mobile phone has a small liquid crystal display device mounted in a small casing. 2. Description of the Related Art In recent years, double-sided display type mobile phones in which small liquid crystal display devices are mounted on the front and back of a thin display portion are commercially available. In this type of mobile phone, a pair of liquid crystal display devices are housed back to back in the casing of the display portion so that the display can be viewed from both the front and back sides.

  In many cases, a liquid crystal display device has a structure in which a backlight as a lighting device is disposed behind a liquid crystal panel. There is also a reflective liquid crystal display device that does not have such a backlight, but its use is limited because the display cannot be viewed in the dark or at night. A liquid crystal display device provided with a backlight has a disadvantage that it becomes thick, but it has been used in most portable electronic devices with the recent trend toward high definition and color display of small liquid crystal display devices. In recent years, transflective liquid crystal display devices that can provide a transmissive display with a backlight and can also perform a reflective display have appeared.

  Since portable electronic devices such as the above-described mobile phones are becoming smaller and thinner year by year, there is a strong demand for thinner liquid crystal display devices. For this reason, thinning of the liquid crystal panel and thinning of the backlight are being promoted (see, for example, Patent Document 1 below).

JP 2001-75093 A (FIGS. 1 and 2)

  However, in the conventional double-sided display type mobile phone, it is difficult to reduce the thickness because a pair of liquid crystal display devices must be housed back to back in the casing. There is a problem that it is thicker and heavier than a normal single-sided display type mobile phone.

  As a technique for solving the above problems, a method of sharing the backlights of the front and back liquid crystal display devices and illuminating a pair of front and back liquid crystal panels with a single backlight is conceivable. However, in general, the display area of the front and back liquid crystal display devices is often different in a double-sided display type mobile phone. Therefore, when the backlight is shared as described above, the luminance distribution of the large main panel is behind The small sub-panel is affected by the lighting effect, and the shadow of the sub-panel may be reflected in the display image of the main panel, which may deteriorate the display quality.

Accordingly, the present invention solves the above-described problems, and the problem is that in a display device capable of realizing double-sided display, the device can be thinned, and illumination means such as a backlight can be used as front and back display means. It is an object of the present invention to provide a display device that can suppress a reduction in display quality in each display means when used in common.

In order to solve the above-described problems, a display device according to the present invention includes a first display unit, a second display unit that is observed from the opposite side of the first display unit, a first display unit, and a second display unit. And an illuminating means for irradiating light to both the first display means and the second display means, and the second display area as the display area of the second display means is the first display means. It is smaller than the first display area, which is the display area, and is arranged so as to overlap the first display area. The illumination means has a first light exit surface facing the first display means, and a second light facing the second display means. A light guide plate having two light output surfaces, and at least one of the first light output surface and the second light output surface of the light guide plate is formed with an uneven shape, A prism having a condensing function in a predetermined direction is interposed between the one light exit surface and the first display means. First condensing means including a plurality of first prism surfaces formed in a stripe shape and a second prism surface in which a plurality of prisms in a direction substantially orthogonal to the first prism surface are formed in a stripe shape is provided, Between the light exit surface and the second display means, there are a third prism surface in which a plurality of prisms having a condensing function in a predetermined direction are formed in stripes, and a prism in a direction substantially orthogonal to the third prism surface. A second condensing means including a plurality of fourth prism surfaces formed in a stripe shape is provided.

The concavo-convex shape provided on the first light output surface or the second light output surface of the light guide plate has a deflection and scattering action for emitting light emitted from the light output surface in the optical axis direction of the display means and in the vicinity thereof. is doing.
Further, for example, a plurality of prisms having a light condensing function in the horizontal direction in the display means as a predetermined direction are provided on the first prism surface, so that the light spreading in the horizontal direction is condensed. The light can contribute to display. Similarly, the second prism surface in which a plurality of prisms in a direction substantially orthogonal to the first prism surface are provided in a stripe shape can condense light spreading in the vertical direction into light that contributes to display.
Therefore, the 1st condensing means provided with the 1st prism surface and the 2nd prism surface can raise the ratio of the light which condenses the light which spreads in a horizontal direction and a perpendicular direction, and contributes to a display. Moreover, the 2nd condensing means provided with the structure substantially the same as a 1st condensing means also has the same effect.
According to this configuration, the light emitted from the light guide plate is scattered by the uneven shape provided on any one of the light emission surfaces, and is repeatedly reflected at the inner interface of the light guide plate, so that the first and second light emission The light is emitted from the surface to the first and second light collecting means. And the light condensed in the 1st and 2nd condensing means injects into a 1st and 2nd display means.
Therefore, the first light collecting means and the second light collecting means are irradiated with light whose luminance is reduced by scattering and whose light quantity is ensured by light collection, so that display quality can be ensured. .

Further, between the first display means and the second display means, there are a first light collecting means, a concavo-convex shape provided on any light emitting surface of the light guide plate, and a second light collecting means. Is provided. Here, the first light collecting means and the second light collecting means can be regarded as a scattering layer that scatters external light incident from the outside of each display means.
Therefore, since it can be considered that there are three scattering layers between the first display means and the second display means, the shade due to the illuminance in the second display means is blurred by the four scattering layers, It is possible to suppress a decrease in display quality in which the shade is reflected on the first display means.
Further, the thickness of the display device is obtained by adding the light guide plate, the first light collecting means, and the second light collecting means to the thicknesses of the first display means and the second display means. The display device can be made thinner than the conventional illumination device provided with a light guide plate (illumination device).
Accordingly, it is possible to provide a display device that can reduce the thickness of the device and can suppress a reduction in display quality in each display means.

According to the display device of the present invention, it is preferable that the concavo-convex shape is provided on both surfaces of the first light emitting surface and the second light emitting surface of the light guide plate.

According to this configuration, since the concavo-convex shape is provided on both surfaces of the first light emitting surface and the second light emitting surface of the light guide plate, between the first display means and the second display means. It can be assumed that there are four scattering layers.
Therefore, the shade by the illuminance in the second display means is blurred by the four scattering layers, and it is possible to further suppress the deterioration in display quality that the shade is reflected in the first display means.

According to the display device of the present invention, a part of the incident light is reflected and a part of the incident light is transmitted between the second light emitting surface of the light guide plate and the second light collecting means. It is preferable that a sheet material having a size covering the first display area is further provided.

According to this configuration, since the sheet material having transflective properties is disposed between the second light emitting surface of the light guide plate and the second display means, the light emitted from the second light emitting surface. A part of the light passes through the sheet material and enters the second display means to illuminate the second display means. Further, the remaining portion of the light emitted from the second light emitting surface is reflected by the sheet material, enters the light guide plate again, and becomes light directed to the first display means.
Therefore, priority can be given to the illumination state of the first display means, and the display quality of the first display means having a large display area can be improved.

According to the display device of the present invention, the display device further includes a case body that opens at least a region corresponding to the first display region and the second display region, and the first light collecting means includes a prism sheet including the first prism surface; The prism sheet having the second prism surface is overlaid, and the second condensing means is formed by overlapping the prism sheet having the third prism surface and the prism sheet having the fourth prism surface. The case body preferably accommodates at least four prism sheets and illumination means.

According to this configuration, the prism sheet having the first prism surface and the prism sheet having the second prism surface, the prism sheet having the third prism surface, and the prism sheet having the fourth prism surface, The first and second light condensing means can be realized with a simple and thin configuration in which the two are superposed.
Furthermore, with one case body, the four prism sheets constituting the first and second light collecting means and the illumination means can be accommodated integrally.

According to the display device of the present invention, the color tone of the case body is preferably white.
According to this configuration, for example, by reflecting the light leaked from the end face in the thickness direction of the light guide plate in the housed illumination means by the white case body, a part of the light can be returned to the light guide plate again. it can. Thereby, the utilization efficiency of illumination light can be improved.

In order to solve the above problems, an electronic apparatus according to the present invention includes the display device described above and a control unit that controls the display device.

According to this configuration, the electronic device includes the display device that can reduce the thickness of the device and can suppress a reduction in display quality in each display unit.
Therefore, a thin electronic device can be realized. Further, it is suitable for a portable electronic device that is required to be thin.

  In an embodiment of the present invention, the transflective means is composed of a base material made of a light transmissive material and a light diffusion layer in which fine particles made of a reflective material are dispersed in the base material. There is a case. According to this, since light is diffused by the fine particles composed of the reflective material dispersed in the base material, the light transmittance and light reflectivity can be adjusted by the size and density of the fine particles, and the light Display unevenness can be reduced by the diffusion action. In particular, with this configuration, the reflectance can be easily increased.

  In an embodiment of the present invention, it is preferable that a light diffusing unit is disposed between the first light exit surface of the light guide member and the first display unit. According to this, since the light diffusing means is disposed between the first light emitting surface and the first display means, the uniformity of the illuminance distribution of the illuminating means can be improved, so the first display means Display unevenness can be further reduced.

  The light diffusing means includes optical characteristics in an overlapping portion overlapping the display area of the second display means in a plane overlapping the display area of the first display means, and the light out of the range. You may be comprised so that the optical characteristic in parts other than a superimposition part may differ. Thereby, the display unevenness of the first display unit may be further reduced.

  The light diffusing means includes a base material made of a light transmissive material, and a light diffusing layer in which fine particles made of a light transmissive material having a refractive index different from that of the base material are dispersed in the base material. May be configured. The light diffusing means may be composed of a base material made of a light transmissive material and a light diffusing layer in which fine particles made of a reflective material are dispersed in the base material. Further, the light diffusing means may be composed of a light diffusing layer in which a fine uneven surface structure is provided on the surface of a light transmissive material.

  Next, it is preferable that the electronic apparatus of the present invention includes the display device according to any one of the above items and a control unit that controls the display device. As the electronic device, a portable electronic device is particularly effective in that the casing can be easily made thinner.

  Next, embodiments of a display device and an electronic apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
First, a liquid crystal display device 100 that is a first embodiment of a display device according to the present invention will be described with reference to FIG. The liquid crystal display device 100 includes first display means 110, second display means 120, and illumination means 130.

  The first display means 110 is a liquid crystal panel, in which substrates 111 and 112 made of glass, plastic, or the like are bonded together with a seal material 113, and a liquid crystal 114 is disposed therein. The liquid crystal 114 is configured to receive a predetermined electric field by electrodes formed on the inner surfaces of the substrates 111 and 112, respectively. A polarizing plate 115 is disposed on the outer surface of the substrate 112 (that is, the front surface side or the viewing side of the first display means), and a polarizing plate 116 is also disposed on the outer surface of the substrate 111 (that is, the back surface side).

  The second display means 120 is also a liquid crystal panel, in which substrates 121 and 122 made of glass, plastic, or the like are bonded together with a sealing material 123, and a liquid crystal 124 is disposed therein. The liquid crystal 124 is configured to receive a predetermined electric field by electrodes formed on the inner surfaces of the substrates 121 and 122, respectively. A polarizing plate 125 is disposed on the outer surface of the substrate 122 (that is, the back side or the observation side of the second display means), and a polarizing plate 126 is also disposed on the outer surface of the substrate 121 (that is, the front side).

  An illumination unit 130 is disposed between the first display unit 110 and the second display unit 120. This illuminating means 130 constitutes a backlight. The illumination unit 130 includes a light source 131 configured by a cold cathode tube, an LED (light emitting diode), and the like, and a light guide plate 132 that receives light from the light source 131. The light guide plate 132 is made of a transparent material such as acrylic resin. In this illumination means 130, the light guide plate 132 is a plate-like body arranged in a posture orthogonal to the optical axis direction of the display device, and the light source 131 is arranged on the side of the light guide plate 132. The light guide plate 132 opposes the light incident surface 132a which is a side end surface to the light source 131, the first light emitting surface 132b which is the front surface (upper surface in the drawing) faces the first display means 110, and the rear surface (lower surface in the drawing). ) Is placed in a posture in which the second light emitting surface 132c is directed to the second display means 120.

  Here, the light guide plate 132 emits illumination light from the first light emitting surface 132b toward the first display means 110 while propagating the light received from the light source 131, and the second light emitting surface. The illumination light is emitted from 132c toward the second display means 120. In the light guide plate 132, light incident at an incident angle smaller than the critical angle with respect to the first light emitting surface 132b and the second light emitting surface 132c is totally reflected, and light incident at an incident angle larger than the critical angle is the first. The light exits from the light exit surface 132b and the second light exit surface 132c. In particular, although not shown, the light source 131 is provided on the first light emitting surface 132b or the second light emitting surface 132c of the light guide plate 132 or on both the first light emitting surface 132b and the second light emitting surface 132c. As the light deflecting means for emitting the light introduced from the light in the optical axis direction of the first display means 110 and the second display means 120 and in the vicinity thereof, a surface uneven shape or a scattering layer can be formed.

  A transflective means 141 is disposed between the second light exit surface 132 c of the light guide plate 132 and the second display means 120. The transflective means 141 is configured to reflect a part of the illumination light of the illumination means to the front side and to transmit at least a part of the remaining part of the illumination light to the back side. Anything is acceptable. For example, it can be composed of a thin metal film, or a metal film having a large number of finely dispersed openings. The transflective means 141 may be provided in a state of being attached to the back surface of the light guide plate 132, or may be formed of a sheet material or a plate-like material separate from the light guide plate 132. Good. The transflective means of the present invention is only required to be disposed between the second light exit surface 132c of the illumination means 130 and the second display means 120, and no other limitations are imposed. However, the transflective means 141 of this embodiment basically covers the entire second light exit surface 132c of the light guide plate 132 and is configured to have a planar optical characteristic. This will be described below as a premise.

  In FIG. 2, the structural example of the said transflective means 141 is shown. In the example shown in FIG. 2A, a reflective thin film 141B, which is a thin film made of a reflective material such as a metal such as aluminum, is formed on the surface of a transparent substrate 141A made of glass, plastic film, or the like. Is. Examples of the reflective material include a white resin, a white pigment such as titanium oxide, and a metal such as aluminum and silver. Here, instead of the transparent substrate 141A, the light guide plate 132 may be used, and the reflective thin film 141B may be formed on the second light emitting surface 132c. This also applies to each configuration shown in FIGS. 2B to 2E described below.

  As the optical characteristics of the reflective thin film 141B, for example, by forming a metal such as aluminum or silver so as to have a film thickness of about 10 to 50 nm, the average transmittance in the visible light region is about 30 to 70%. can do. The thin film can be formed by vapor deposition, sputtering, laser ablation, or the like. The reflectance and transmittance in this configuration example can be adjusted by the film thickness.

  Further, the transflective means can be formed of a known dielectric multilayer film in addition to the case of the reflective material as described above.

  In the configuration example shown in FIG. 2B, a reflective thin film 141C, which is a thin film made of a reflective material such as a metal such as aluminum, is formed on the surface of the transparent substrate 141A. Examples of the reflective material include a white resin, a white pigment such as titanium oxide, and a metal such as aluminum and silver. The reflective thin film 141C is configured so that the average reflectance in the visible light region is about 90% or more as a whole, and a large number of minute openings 141Ca are formed. The minute openings 141Ca are distributed over the entire film surface of the reflective thin film 141C. The converted opening diameter of the minute opening 141Ca (opening diameter in a circular opening having the same opening area) is preferably about 1 to 100 μm, and preferably about 5 to 30 μm. In particular, it is desirable that the pixel size is smaller than the pixel size of the first display unit and the second display unit and is smaller than the pixel pitch. The reflectance and transmittance in this configuration example can be adjusted by the aperture ratio of the minute aperture 141Ca. This opening ratio is determined by the converted opening diameter and the formation density of the minute openings 141Ca.

  The configuration example shown in FIG. 2C includes a light diffusion layer 141D basically made of a light transmissive material on the surface of the transparent substrate 141A. The light diffusion layer 141D includes a transparent base material 141d1 made of an acrylic resin or the like, and fine particles 141d2 dispersedly arranged in the base material 141d1. The base material 141d1 and the fine particles 141d2 are made of materials having different refractive indexes. Examples of the fine particles include silica particles and acrylic resins. The particle size of the fine particles is desirably about 1 to 10 μm, particularly about 4 to 5 μm.

  In this configuration example, since fine particles having different refractive indexes are dispersed and arranged in the base material, light is scattered or diffused. Therefore, when viewed macroscopically, a part of the light is reflected and the remaining part is transmitted. Characteristics are obtained. The reflectance and transmittance of this configuration example can be adjusted by the refractive index difference between the substrate and the fine particles, the size and distribution density of the fine particles, and the like.

  The configuration example shown in FIG. 2D includes a light diffusion layer 141E basically made of a light transmissive material on the surface of the transparent substrate 141A. The light diffusion layer 141E includes a transparent base material 141e1 made of an acrylic resin or the like, and light reflective fine particles 141e2 dispersedly arranged in the base material 141e1. The fine particles 141e2 are made of a reflective material. Examples of the reflective material include white resin, white pigment such as titanium oxide, and metal such as aluminum and silver. The particle diameter of the fine particles 141e1 is preferably about 1 to 10 μm, particularly about 2 to 3 μm.

  In this configuration example, since fine particles made of a reflective material are dispersed and arranged in the base material, light is scattered or diffused, so that when viewed macroscopically, part is reflected and the rest is transmitted. Optical characteristics such as are obtained. The reflectance and transmittance of this configuration example can be adjusted by the reflectance of fine particles, the size and density of fine particles, and the like.

  In the configuration example shown in FIG. 2E, the same reflective thin film 141B as that made of the reflective material shown in FIG. 2A is formed on the surface of the transparent substrate 141A, and the thin film 141B is formed on the thin film 141B. Further, a scattering layer 141F made of a light-transmitting material (preferably a transparent material) and having fine irregularities on the surface is formed. The unevenness of the surface of the scattering device 141F is formed to a depth of about 2 to 3 μm with a period of about 1 to 10 μm, preferably about 3 to 4 μm, for example. The surface irregularities can be formed by a patterning technique such as a photolithography method. For example, the surface irregularities can be formed by applying a transparent photosensitive resin, then exposing with a mask pattern having openings at a period corresponding to the surface irregularities, and then developing. Here, a process for forming a smooth surface irregularity shape, such as applying another transparent resin on the transparent resin after development, or heating and softening the transparent resin after development. May be additionally implemented.

  According to this configuration example, the reflection and transmission characteristics corresponding to the thickness of the reflective thin film 141B can be obtained as described above, and the light incident on the reflective thin film 141B and the reflected light are scattered by the scattering layer 141F. Therefore, it has a light diffusion function, and the uniformity of the luminance distribution in the first display means 110 and the second display means 120 can be improved.

  A light diffusing unit 142 is disposed between the light guide plate 132 and the first display unit 110. The light diffusing unit 142 appropriately diffuses the light emitted from the light guide plate 132, thereby causing display unevenness (brightness in the display surface) due to the structure of the light guide plate 132 and the rear side (lower side in the drawing). Variation). The light diffusing means 142 is, for example, a material in which fine particles having different refractive indexes (for example, having a particle diameter of about 2 to 3 μm) made of silica, acrylic resin, or the like are dispersed in a base material such as acrylic resin. Further, those having a fine irregular surface shape on the surface can be used. More specifically, a structure similar to that shown in FIG. 2C or FIG. 2D or a structure in which the reflective thin film 141B is removed from the structure shown in FIG. Can do. The light diffusing unit 142 may be provided in a state of being attached to the front surface of the light guide plate 132 or may be formed of a sheet material or a plate-like material that is separate from the light guide plate 132.

  A light diffusing unit 145 is also disposed between the light guide plate 132 and the second display unit 120 (between the transflective unit 141 and the second display unit 120 in this embodiment). . The light diffusing unit 145 is configured in the same manner as the light diffusing unit 142.

  In the present embodiment, the overlapping portion that also overlaps the display area of the second display means 120 in a plane that overlaps the display area of the first display means 110 and the above-mentioned range. Therefore, in order to improve the uniformity of the display surface of the first display means, the light diffusing means is used to adjust the degree of diffusion between the superposed part and the other parts. It is also possible to configure so that (for example, haze values) are different.

  In the present embodiment, in the first display unit 110 and the second display unit 120, the light collection units (prism sheets) 143, 144, 146, and 147 are used as illumination units in order to increase the proportion of light that substantially contributes to display. 130 and the first display unit 110, and between the illumination unit 130 and the second display unit 120, respectively. These condensing means are provided with a prism surface for refracting light, and the prism surface is configured to direct the light toward the optical axis direction (vertical direction in the figure) of the display device and the vicinity thereof. More specifically, the prism surface is formed by a plurality of ridges having a triangular cross section arranged in stripes on the surface of the light collecting sheet. The condensing means 143 and 144 and the condensing means 146 and 147 are arranged so that the extending directions of the ridges are substantially orthogonal to each other.

  Next, the effect of this embodiment which has the structure demonstrated above is demonstrated. In the following description, in order to simplify the description, the first display means 110 and the second display means 120 which are liquid crystal panels are both configured to perform display in the TN liquid crystal mode, and the polarizing plate 115 is The linearly polarized light A (first polarized light) having a vibration plane parallel to the paper surface of the figure is transmitted, and the linearly polarized light B (second polarized light) having a vibration surface orthogonal to the paper surface of the figure is reflected. The linearly polarized light B (third polarized light) is transmitted and the linearly polarized light A (fourth polarized light) is absorbed. The polarizing plate 125 transmits the linearly polarized light A and absorbs the linearly polarized light B, and the polarizing plate 126 transmits the linearly polarized light B and absorbs the linearly polarized light A. That is, in general, the orientation relationship of the vibration planes of the first polarization to the fourth polarization is arbitrary, but in the following description, the first polarization and the fourth polarization indicate the same polarization state, and the second polarization And the third polarization show the same polarization state.

  Light emitted from the light source 131 is introduced into the light guide plate 132 and is gradually emitted to the front side and the back side while propagating through the light guide plate 132. First, the illumination light emitted to the first display means 110 side passes through the light diffusing means 142 to become linearly polarized light B by the polarizing plate 116, and enters the liquid crystal 114 through the light collecting means 143 and 144. Here, when the liquid crystal 114 is in the OFF state, when it passes through the liquid crystal 114, it becomes linearly polarized light A due to its optical rotation, passes through the polarizing plate 115, and is emitted to the front side as transmitted light T1. When the liquid crystal 114 is in the ON state, the linearly polarized light B remains as it passes through the liquid crystal 114 and is absorbed by the polarizing plate 115.

  On the other hand, external light incident on the first display unit 110 passes through the polarizing plate 115 to become linearly polarized light A and enters the liquid crystal 114. Here, when the liquid crystal 114 is in the OFF state, it becomes linearly polarized light B, passes through the polarizing plate 116, enters the light guide plate 132, is partially reflected by the transflective means 141, and passes through the polarizing plate 116 again. It passes through the liquid crystal 114 to become linearly polarized light A, passes through the polarizing plate 115, and is emitted as reflected light RD1. When the liquid crystal 114 is in the ON state, the linearly polarized light A that has passed through the polarizing plate 115 out of the external light remains as the linearly polarized light A even after passing through the liquid crystal 114, and is thus absorbed by the polarizing plate 116.

  In the case where the light collecting means 143 and 144 are arranged, the external light is scattered when entering the light collecting means, so that the reflected light RD1 cannot be obtained substantially. Therefore, when it is desired to use the reflected light RD1 effectively, it is preferable not to arrange the light collecting means.

  Next, a part of the illumination light emitted from the illumination unit 130 to the second display unit 120 side is transmitted through the semi-transmissive reflection unit 141, passes through the light diffusion unit 145, and passes through the polarizing plate 126. B and passes through the liquid crystal 124. When the liquid crystal 124 is in the OFF state, the linearly polarized light B passes through the liquid crystal 124 to become linearly polarized light A, passes through the polarizing plate 125, and is emitted to the back side as transmitted light T2. When the liquid crystal 124 is in the ON state, the linearly polarized light B remains as it is after passing through the liquid crystal 124 and is absorbed by the polarizing plate 125.

  On the other hand, of the external light incident on the second display unit 120, the linearly polarized light A passes through the polarizing plate 125 and enters the liquid crystal 124. When the liquid crystal 124 is in the OFF state, the linearly polarized light A becomes the linearly polarized light B, passes through the polarizing plate 126 and the light diffusing unit 143, is partially reflected by the transflective unit 141, and the other part is in the light guide plate 132. To be introduced. The linearly polarized light B reflected by the transflective means 141 passes through the light diffusing means 143 and the polarizing plate 126 as it is, passes again through the liquid crystal 124 to become linearly polarized light A, passes through the polarizing plate 125, and is emitted as reflected light RD2. To do. When the liquid crystal 124 is in the ON state, the linearly polarized light A is absorbed by the polarizing plate 126 because it remains as the linearly polarized light A even after passing through the liquid crystal 124.

  When the light condensing means 146 and 147 are arranged, the external light is scattered when entering the light condensing means, so that it is substantially impossible to obtain the reflected light RD2. Therefore, when it is desired to use the reflected light RD2 effectively, it is preferable not to arrange the light collecting means.

  As described above, in the present embodiment, the first display unit 110 performs display using the transmitted light T1 and the reflected light RD1. In the second display means 120, display is performed by the transmitted light T2 and the reflected light RD2. The presence of the reflected light RD1 and the reflected light RD2 suppresses a decrease in display visibility when viewed in a bright place such as outdoors or when the amount of illumination light of the illumination unit 130 is reduced. Is possible.

  In the present embodiment, since the illumination unit 130 is configured to irradiate light to both the first display unit 110 and the second display unit 120, in particular, between the first display unit 110 and the second display unit 120. Since the arranged light guide plate 132 is used in common, the entire display device 100 can be reduced in thickness and weight. Further, the provision of the transflective means 141 makes it possible to distribute the light in the light guide plate 132 to both the first display means 110 and the second display means 120 on the front and back sides, and from the light guide plate 132. Uniformity of illumination light applied to both the front and back sides can be improved, and external light incident on the first display means 110 and the second display means 120 can be reflected and used as part of display light. Is also possible.

  In particular, due to the presence of the transflective means 141, the illuminance distribution from the illumination means 130 to the first display means 110 is less likely to be optically affected by the presence of the second display means 120. Therefore, even when the display area of the first display means 110 is set larger than the display area of the second display means 120 as shown, the display of the second display means 120 is displayed on the display surface of the first display means 110. The shadow of the region is less likely to appear, and the display quality of the first display means 110 is improved.

  As described above, the display area of the first display means 110 and the display area of the second display means overlap in a plane, but one display area is included in the other display area. In general, when there is a portion that does not overlap part of both display areas, display unevenness is generally noticeable. Therefore, in these cases, the above configuration is particularly effective. However, the present invention is not limited to the above case. Normally, when the display means on both the front and back sides are lit by the common illumination means, unevenness in the illuminance distribution of the illumination means tends to occur. Therefore, unlike the above, even when both display areas have the same size and overlap each other in a substantially planar manner, the uniformity of the brightness of each display means is ensured. Therefore, the configuration of the present invention is technically meaningful.

[Second Embodiment]
Next, a second embodiment of the display device according to the present invention will be described with reference to FIG. Since the display device of the second embodiment has basically the same configuration as that of the first embodiment shown in FIG. 1 except that the transflective means is different, illustration and description thereof are omitted.

As shown in FIG. 3A, the transflective means 241 of the present embodiment covers the second light of the light guide plate 132 so as to cover the entire area AR1 that overlaps the display area of the first display means 110 in plan view. It is disposed between the emission surface 132 c and the second display means 120.
In the transflective means 241, the overlapping portion AR2 that overlaps the display area of the second display means 120 in a plane is an opening 241A, and the portion AR3 other than the overlapping portion AR2 in the range AR1 emits visible light. It is a reflecting portion 241R that reflects.

  In this configuration, since the light irradiation from the light guide plate 132 to the second display unit 120 is performed through the opening 241A, the display brightness of the second display unit 120 can be easily obtained. Further, in the first display unit 110, substantially all of the light is reflected in the portion AR3, so that the amount of light contributing to the display as a whole can be increased. However, in this case, since the intensity of the illumination light applied to the first display unit 110 is reduced in the overlap portion AR2, the light diffusion action by the light diffusion unit 142, the light emission distribution of the light guide plate 132, and the like are adjusted. It is desirable to adopt a configuration that relaxes the intensity distribution of illumination light.

  FIG. 3B shows a modification of the above embodiment. The transflective means 241 'is formed so that a large number of minute openings 241A' are dispersedly arranged on the reflecting surface in the overlapping portion AR2, and the portion other than the overlapping portion AR2 does not have an opening and reflects light. It is the reflection part 241R to be made. In this modification, the second display unit 120 is illuminated with light passing through the minute opening 241A ′ formed in the overlapping portion AR2. However, in this overlapping portion AR2, the light is reflected toward the first display means 110 by the reflecting surface other than the minute aperture 241A ′, and therefore the overlapping portion AR2 and the other portion AR3 on the display surface of the first display means 110. The difference in display brightness between and can be reduced. Even in this case, in order to further reduce the display unevenness in the first display means 110, the light diffusing action by the light diffusing means 142, the light emission distribution of the light guide plate 132, etc. are adjusted, and the intensity distribution of the illumination light. It is desirable to adopt a configuration that alleviates this.

[Third Embodiment]
Next, a third embodiment according to the present invention will be described with reference to FIG. Since the display device of this embodiment has basically the same configuration as that of the first embodiment shown in FIG. 1 except that the transflective means is different, illustration and description thereof are omitted.

  As shown in FIG. 4A, in the transflective means 341, the overlapping portion AR2 has a predetermined reflectance (for example, 30 to 70%) and transmittance (for example, 30 to 70%) in the range AR1. The portion AR3 other than the overlapping portion AR2 is composed of the transflective material 341A and has substantially the same reflectance (for example, 30 to 70%) as the overlapping portion AR2, but the transmittance is lower than that of the overlapping portion AR2. 341B. The transmittance of the reflective material 341B in AR3 is preferably almost 0%. Such a material can be easily formed especially by a dielectric multilayer film.

  Thereby, in the overlapping portion AR2 in the range AR1, the illumination light from the illumination unit 130 can be reflected toward the first display unit 110, and at the same time, the illumination light can be transmitted toward the second display unit 120. Therefore, both display means can be illuminated simultaneously. Further, the portion AR3 other than the overlapping portion AR2 does not transmit unnecessary light behind due to its low transmittance, and its reflectance is substantially the same as that of the overlapping region AR2, so that the first display means 110 is provided. Display unevenness can be reduced.

  In this configuration example, if the display unevenness of the first display unit 110 is to be eliminated, light loss due to the absorption of illumination light occurs in the portion AR3, so that the light use efficiency as a whole decreases. In order to increase the light utilization efficiency, it is necessary to reduce the optical loss in the portion by relatively increasing the reflectance of the portion AR3 compared to the overlapping portion AR2, and the first display means 110 that can be generated thereby. The display unevenness is preferably alleviated by the structure of the light guide plate 232, the light diffusion means 142, or the like.

  FIG. 4B shows a modification of the above embodiment. The transflective means 341 'is entirely made of a reflective material, but a large number of minute openings 341A' are dispersedly arranged in the overlapping portion AR2. Further, in the portion AR3 other than the overlapping portion AR2, minute absorbents 341B ′ made of black resin or the like are dispersedly arranged instead of the minute openings 341A ′.

  The transflective means 341 ′ is configured so that light can be applied to the second display means 120 behind by the minute opening 341A ′ in the overlapping part AR2, and in the other part AR3, the semi-transmissive reflecting means 341 ′ is minute. By forming the absorbing material 341B ′, the difference in reflectance from the overlap portion AR2 is reduced. Thereby, display unevenness of the first display means 110 can be reduced.

[Fourth Embodiment]
Next, a fourth embodiment of the display device according to the present invention will be described with reference to FIG. The display device of this embodiment shows a structure in which the display device of the above embodiment is housed in a case body made of synthetic resin or the like. Accordingly, the display device of the present embodiment has basically the same configuration as that of the first embodiment shown in FIG. 1 except that the display device is housed in the case body. Therefore, the illustration thereof is simplified and the description thereof is omitted. To do.

  As shown in FIG. 5 (a), the display device 100 'includes the first display means 110, the second display means 120, the illumination means 130, and the other structures not shown, which are the same as those in the above embodiments. The case body 150 is accommodated. Case body 150 can be formed of, for example, a white synthetic resin. Constructing the case body 150 with a white material is preferable in terms of increasing the use efficiency of the illumination light of the illumination means 130 because the light leaking from the light guide plate 132 can be reflected and returned to the light guide plate 132 again. .

  In this embodiment, an optical sheet 151 having predetermined optical characteristics in a region where the second display unit 120 is not disposed on the surface of the second light exit surface of the light guide plate 132 of the illumination unit 130 (the portion AR3). Is arranged. The optical sheet 151 is made of a material that exhibits substantially the same reflectance as the second display unit 120 when viewed from the first display unit 110 side. Accordingly, even if the transflective means 141 has uniform optical characteristics over the entire surface, display unevenness on the display surface of the first display means can be reduced.

  FIG. 5B shows a modification of the above embodiment. In the display device 100 ″ of this example, the first display unit 110, the second display unit 120, the illumination unit 130, and the other configuration (not shown) that are the same as those of the above embodiments are accommodated in the case body 160. The body 160 is made of a material that exhibits substantially the same reflectivity as the second display unit 120 when viewed from the first display unit 110. Thus, the transflective unit 141 is uniform over the entire surface. Even if it has an optical characteristic, the display unevenness of the display surface of the first display means can be reduced.

  Note that the optical sheet 151 and the case body 160 are the second display means when viewed through the illumination means 130 from the first display means 110 side, regardless of the configuration of the transflective means 141 and the light guide plate 132. What is necessary is just to be comprised so that the illumination intensity distribution of the part in which the display area of 120 exists, and the part in which the optical sheet 151 and the case body 160 are arrange | positioned may become uniform.

[Fifth Embodiment]
Next, with reference to FIG.6 and FIG.7, embodiment of the electronic device provided with the display apparatus 100 of the said 1st Embodiment is described. As shown in FIG. 6, the electronic apparatus of this embodiment includes a control unit 1100 that controls the first display unit (liquid crystal display panel) 110 and a control unit that controls the second display unit (liquid crystal display panel) 120. 1200. The control means 1100 and 1200 are controlled by a central control unit 1000 configured by a microcomputer or the like installed in the electronic device.

  The first display unit 110 and the second display unit 120 are connected to the drive circuits 110D and 120D formed of a semiconductor IC or the like mounted on the panel or connected to the panel via a wiring member. These drive circuits 110D and 120D are connected to the control means 1100 and 1200. The control means 1100 and 1200 include display information output sources 1110 and 1210, display processing circuits 1120 and 1220, power supply circuits 1130 and 1230, and timing generators 1140 and 1240.

  Display information output sources 1110 and 1210 are a memory composed of a ROM (Read Only Memory), a RAM (Random Access Memory), etc., a storage unit composed of a magnetic recording disk, an optical recording disk, etc. And display information in the form of an image signal of a predetermined format and the like based on various clock signals generated by the timing generators 1140 and 1240. .

  The display information processing circuits 1120 and 1220 include various known circuits such as a serial-parallel conversion circuit, an amplification / inversion circuit, a rotation circuit, a gamma correction circuit, and a clamp circuit, and execute processing of input display information. Image information is supplied to the drive circuit together with the clock signal CLK. The drive circuits 110D and 120D include a scanning line drive circuit, a data line drive circuit, and an inspection circuit. The power supply circuits 1130 and 1230 supply predetermined voltages to the above-described components.

  The central control unit 1000 appropriately sends on / off instructions, original data of display information, and the like to the display information output sources 1110 and 1210 of the control means 1100 and 1200, and displays display information corresponding thereto as a display information output source 1110. , 1210, and appropriate display images are displayed on the first display unit 110 and the second display unit 120 via the control units 1100 and 1200 and the drive circuits 110D and 120D. The central control unit 1000 is configured to perform control such as turning on and off the light source 131.

  FIG. 7 shows a mobile phone 2000 which is an embodiment of an electronic apparatus according to the present invention. The cellular phone 2000 includes a main body 2001 having various operation buttons and a built-in microphone, and a display unit 2002 having a display screen and an antenna and a built-in speaker. The main body 2001 and the display 2002 are mutually connected. It is configured to be foldable. The display unit 100 incorporates the display device 100, the display screen of the first display unit 110 is visible on the inner surface, and the display of the second display unit 120 is displayed on the outer surface. The screen is configured to be visible.

  In the present embodiment, as shown in FIG. 7A, by opening the display unit 2002 from the main body unit 2001, the first display unit 110 is turned on by a command from the central control unit 1000, and a predetermined image is displayed. Further, as shown in FIG. 7B, the display unit 2002 is folded on the main body unit 2001, whereby the first display unit 110 is turned off. Instead, the second display unit 120 is turned on and a predetermined image is displayed. Can be configured to be displayed.

  In the present embodiment, since the display device 100 is thinned as described above, the display unit 2002 can be thinned, the internal structure thereof can be simplified, and the assembly work can be easily performed. It becomes possible to do. Here, the electronic apparatus according to the present embodiment may be configured to include the display devices according to the second to fourth embodiments.

  It should be noted that the electro-optical device and the electronic apparatus of the present invention are not limited to the illustrated examples described above, and various modifications can be made without departing from the scope of the present invention. For example, in each of the above embodiments, a liquid crystal display panel is used as the electro-optical panel, but various electro-optical panels such as an organic electroluminescence panel, a plasma display panel, and a field emission display are used as the electro-optical panel of the present invention. You can also. In the above-described embodiment, a passive matrix liquid crystal display panel is basically illustrated, but an active matrix liquid crystal display panel can also be used in the present invention.

1 is a schematic sectional view showing the configuration of a first embodiment according to the present invention. The schematic sectional drawing which shows the structure (a)-(e) of the transflective means of 1st Embodiment. The schematic plan view (a) and (b) which shows the structure of the transflective means of 2nd Embodiment which concerns on this invention. The schematic plan view (a) and (b) which shows the structure of the transflective means of 3rd Embodiment which concerns on this invention. Schematic sectional drawing (a) and (b) which show schematic structure of 4th Embodiment which concerns on this invention. FIG. 11 is a configuration block diagram illustrating a configuration example of an electronic device. FIGS. 3A and 3B are schematic perspective views of a mobile phone showing a configuration example of an electronic device. FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Display apparatus, 110 ... 1st display means, 120 ... 2nd display means, 130 ... Illumination means, 115, 116, 125, 126 ... Polarizing plate, 131 ... Light source, 132 ... Light guide plate, 141 ... Transflective means 142,145 ... light diffusing means, 143,144,146,147 ... light collecting means

Claims (6)

First display means, second display means observed from the opposite side of the first display means to the observation side,
An illumination unit that is disposed between the first display unit and the second display unit and that irradiates light to both the first display unit and the second display unit;
The second display area that is the display area of the second display means is smaller than the first display area that is the display area of the first display means, and is arranged so as to overlap the first display area,
The illumination means includes a plate-shaped light guide plate having a first light emitting surface facing the first display means and a second light emitting surface facing the second display means,
An uneven shape is formed on at least one of the first light exit surface and the second light exit surface of the light guide plate,
Between the first light exit surface of the light guide plate and the first display means, a first prism surface in which a plurality of prisms having a condensing function in a predetermined direction are formed in a stripe shape, and the first prism A first light collecting means including a second prism surface in which a plurality of prisms in a direction substantially orthogonal to the surface is formed in a stripe shape;
Between the second light exit surface and the second display means, a third prism surface in which a plurality of prisms having a condensing function in a predetermined direction are formed in a stripe shape, and substantially orthogonal to the third prism surface And a second condensing means including a fourth prism surface in which a plurality of prisms in the direction to be formed are formed in a stripe shape. The display device according to claim 1, wherein the uneven shape is provided on both surfaces of the first light emitting surface and the second light emitting surface of the light guide plate. Between the second light exit surface of the light guide plate and the second light collecting means, the first display region that reflects part of incident light and transmits part of incident light is provided. The display device according to claim 1, further comprising a sheet material having a size to cover. A case body that opens at least an area corresponding to the first display area and the second display area;
The first light collecting means is configured by superimposing a prism sheet provided with the first prism surface and a prism sheet provided with the second prism surface,
The second light collecting means is configured by superimposing a prism sheet having the third prism surface and a prism sheet having the fourth prism surface,
The display device according to claim 1, wherein the case body houses at least the four prism sheets and the illumination unit. The display device according to claim 4, wherein a color tone of the case body is white. An electronic apparatus comprising: the display device according to claim 1; and a control unit that controls the display device.

Images