JP2015194628A - Double-sided display apparatus, lighting device, and light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided display apparatus that can be made thin although two display panels can be viewed from both outer sides, a lighting device, and a light guide plate.SOLUTION: A double-sided display apparatus, a lighting device, and a light guide plate include: two display panels provided such that display planes thereof are opposed to each other; a single light guide plate provided between the two display panels, and a light source for making light incident from an end face of the light guide plate. Surfaces on both sides, facing display panel sides, of the light guide plate are light emission surfaces for emitting light, emitted by the light source and made incident from an end face of the light guide plate toward the display panels respectively, and the light from the light emission surface on both the sides to the respective display panel, facing the display panel sides, of the light guide plate are uniform or substantially uniform in light quantity.

Description

  The present invention relates to a double-sided display device capable of visually recognizing two display panels from both outer sides.

  Most display devices have a structure that can be viewed from one side, and depending on the display location and application, it is desired to install a display device that can be observed from the side opposite to the display surface.

  For example, Patent Documents 1 to 3 disclose a double-sided display device configured so that two display panels can be viewed from both outer sides.

  That is, Patent Document 1 is a double-sided display device for outdoor installation, in which both ends of two display panel units are fixed to two vertical frames, and a space for heat dissipation between the two display panel units. There is disclosed a double-sided display device provided with.

  Japanese Patent Application Laid-Open No. H10-228561 provides a light guide plate for irradiating each LCD with light on the back of each LCD (Liquid Crystal Display), and both sides are configured so that the LCD is fixed by claws provided on the light guide plate. A display device is disclosed.

  Patent Document 3 discloses a suspended display device or a stand-type display device in which two liquid crystal display devices are overlapped.

JP 2010-102227 A JP 2003-185994 A JP 2000-75815 A JP 2004-228092 A

  The double-sided display devices disclosed in each of these Patent Documents 1 to 3 are configured by simply superimposing conventional single-sided display devices so that the two display panels can be viewed from both outsides. Is. Therefore, the double-sided display device configured as described above has a problem that there is a limit to reducing the thickness of the entire double-sided display device.

  Accordingly, an object of the present invention is to provide a double-sided display device, an illumination device, and a light guide plate that can realize a reduction in thickness while allowing two display panels to be viewed from both outer sides.

  In addition, as a configuration related to the present invention, in Patent Document 4, in a display device that visually recognizes one display panel from one side, a condensing dot pattern including an ultraviolet curable substance that is cured by ultraviolet rays is disposed on a light guide plate. A configuration is disclosed.

  However, the configuration described in Patent Document 4 is based on a display device that visually recognizes one display panel from one side, and in order to form a condensing dot pattern using a pattern mask, the condensing dot pattern (See paragraphs [0092] to [0108] of Patent Document 4) and does not assume a double-sided display device that can visually recognize two display panels from both outsides. .

  In order to solve the above-described problems, the present invention provides the following double-sided display device, illumination device, and light guide plate.

(1) Double-sided display device Two display panels provided so that their display surfaces are opposite to each other, a single light guide plate provided between the two display panels, and light from an end face of the light guide plate A light emitting unit that emits light that is emitted from the light source and incident from the end surface of the light guide plate toward the display panels. The light guide plate is configured to make the amount of light from the light emitting surfaces on both sides facing the display panel side of the light guide plate uniform or substantially uniform. Display device.

  As a specific aspect of the double-sided display device according to the present invention, for example, two display panels provided so that their display surfaces are opposite to each other, and a single light guide plate provided between the two display panels, A light source that makes light incident from an end surface of the light guide plate, and both surfaces of the light guide plate that face the display panel are emitted from the light source and incident from the end surface of the light guide plate. Each of the light emitting surfaces on both sides facing the display panel of the light guide plate is provided with a transparent pattern made of a transparent material. The aspect currently described can be illustrated.

(2) Illumination device The illumination device is provided in the double-sided display device according to the present invention, includes the light source and the light guide plate, and both surfaces of the light guide plate facing the display panel are emitted from the light source and are guided. A light exit surface that emits light incident from the end face of the light plate toward the display panels, and is provided on at least one of the light exit surfaces on both sides of the light guide plate facing the display panel. Is provided with a transparent pattern formed of a transparent material.

(3) Light guide plate Provided in the double-sided display device according to the present invention or the lighting device according to the present invention, light on both sides facing the display panel is emitted from the light source and incident from the end surface. Each of the light emitting surfaces on both sides facing the display panel is provided with a transparent pattern made of a transparent material. The light emitting surfaces emit light toward the display panel. A light guide plate characterized by that.

  In the present invention, the transparent material can be exemplified as a transparent ultraviolet curable resin material that is cured by ultraviolet rays.

  In the present invention, the transparent pattern is provided only on one side of the light emitting surfaces on both sides facing the display panel side of the light guide plate, and the light on both sides facing the display panel side of the light guide plate. A mode in which light diffusing sheets having light diffusibility are respectively arranged on the emission surface can be exemplified.

  In this invention, the said transparent pattern can illustrate the aspect which consists of a some pattern formation part.

  In the present invention, it is possible to exemplify an aspect in which the size is the same or substantially the same in each of the pattern forming parts constituting the transparent pattern, and the pitch is reduced as the distance from the light input part from the light source is increased. .

  In the present invention, it is possible to exemplify an embodiment in which the individual pattern forming portions constituting the transparent pattern are irregularly formed.

  In the present invention, it is possible to exemplify an embodiment in which the size of each of the pattern forming portions constituting the transparent pattern is 300 μm or less, more preferably 70 μm or less.

  In the present invention, the transparent pattern can be formed by printing.

  In the present invention, the light guide plate can be exemplified as having a thickness of 4 mm or less.

  In the present invention, a pair of optical members each including a light diffusing sheet positioned at a position closest to the light emitting surface and having a light diffusing property on the light emitting surfaces on both sides facing the display panel of the light guide plate Can be exemplified.

  In the present invention, an example in which the pair of optical members has a thickness of 2 mm or less can be exemplified.

  In the present invention, an embodiment in which the spatial distance between the light guide plate and the display panel is 5 mm or less can be exemplified.

  According to the present invention, it is possible to provide a double-sided display device, an illuminating device, and a light guide plate that can realize thinning while allowing the two display panels to be viewed from both outer sides.

1 is a perspective view of a double-sided display device according to an embodiment of the present invention. It is sectional drawing which expands and shows the cross section along the AA cut surface line of the double-sided display apparatus shown in FIG. It is sectional drawing for demonstrating the reflection state of the light which injected into the light-guide plate from the light source. It is a front view which shows roughly the transparent pattern which concerns on 1st Embodiment formed in the light-guide plate. It is a front view which shows roughly the transparent pattern which concerns on 2nd Embodiment formed in the light-guide plate. It is a front view which shows roughly the transparent pattern which concerns on 3rd Embodiment formed in the light-guide plate. It is a front view which shows roughly the transparent pattern which concerns on 4th Embodiment formed in the light-guide plate. It is a graph which shows the result of the Example of the double-sided display apparatus which concerns on this Embodiment.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a perspective view of a double-sided display device 100 according to an embodiment of the present invention. 2 is an enlarged cross-sectional view of the double-sided display device 100 shown in FIG. 1 taken along the line AA.

  The double-sided display device 100 can visually recognize the two display panels 11 and 12 (see FIG. 2) provided from both outsides so that the display surfaces 11a and 12a are opposite to each other (facing in opposite directions). The display unit 110 includes two display surfaces 11a and 12a (see FIG. 2) that can be displayed in opposite directions.

  In the double-sided display device 100, a direction orthogonal to the display surfaces 11a and 12a is referred to as a “front-rear direction X”, and a vertical direction when the stand unit 120 (see FIG. 1) is installed on the floor surface is referred to as a “height direction Z”. The direction perpendicular to both the front-rear direction X and the height direction Z is referred to as a “width direction Y”.

  The display unit 110 in the double-sided display device 100 has one display panel 11 having one display surface 11a for displaying an image, the other display surface 12a for displaying an image, and the side opposite to the display surface 12a. The other display panel 12 (see FIG. 2) is provided so that the surface 12b (back surface) of the display panel 11 faces the surface 11b (back surface) opposite to the display surface 11a of one display panel 11. Hereinafter, the two display panels 11 and 12 may be simply referred to as “display panels 11 and 12”.

  In this example, the display panels 11 and 12 constituting the display unit 110 in the double-sided display device 100 are liquid crystal display panels. Specifically, the display panels 11 and 12 are configured by sealing liquid crystal between a TFT (Thin Film Transistor) substrate and a CF (Color Filter) substrate.

  In this example, the double-sided display device 100 is configured as a stand-type display device, and a stand unit 120 (see FIG. 1) for installing the display unit 110 upright with respect to a floor surface such as a road or a passage. ). The display unit 110 in the double-sided display device 100 further includes a holding unit 40 (see FIG. 1) that is supported by the stand unit 120 and holds the display panels 11 and 12 and the lighting device 20 (see FIG. 2). The double-sided display device 100 may be configured as a suspension type display device.

  The holding unit 40 is supported by the stand unit 120 and supports a pair of first holding units 41 and 41 that support the display panels 11 and 12 and the lighting device 20 in the height direction Z on both sides in the width direction Y. A pair of second holding portions 42, 42 that are supported by the first holding portions 41, 41 and support the display panels 11, 12 on both sides in the height direction Z are provided between the first holding portions 41, 41.

  As shown in FIG. 2, the first holding unit 41 fixes the light guide plate 21 in the lighting device 20 and the pair of optical members 30 and 30 disposed on both sides of the light guide plate 21 in the front-rear direction X from the outside in the front-rear direction X. And a pair of clamping portions 41b and 41b for clamping the two display panels 11 and 12 together with the pair of fixing portions 41a and 41a. The light guide plate 21 and the pair of optical members 30 and 30 are fixed to the pair of fixing portions 41a and 41a via spacers SP and SP provided on both sides in the front-rear direction X. One display panel 11 is sandwiched between one fixing part 41a and one clamping part 41b via spacers SP, SP provided on both sides in the front-rear direction X. The other display panel 12 is sandwiched between the other fixing portion 41a and the other sandwiching portion 41b via spacers SP, SP provided on both sides in the front-rear direction X.

  The display panels 11 and 12 are rectangular plates that are horizontally long when viewed from the front (see FIG. 1). In the present embodiment, the two display panels 11 and 12 have the same configuration. That is, the two display panels 11 and 12 have the same shape and the same size.

  In the present embodiment, the light guide plate 21 is larger in size in front view than the display surfaces 11 a and 12 a in the display panels 11 and 12 and smaller in size in front view of the display panels 11 and 12. Further, the pair of optical members 30 has a front view size substantially the same as the front view size of the light guide plate 21.

  Specifically, when the two display panels 11 and 12 project the display surfaces 11a and 12a in the front-and-rear direction X with respect to a virtual plane that is perpendicular to the front-and-rear direction X, the projection areas for the display surfaces 11a and 12a are projected. Are positioned so as to coincide with each other. Further, the light guide plate 21 has a projection area when the surfaces (light emitting surfaces 21a and 21b) corresponding to the display panels 11 and 12 are projected in the front-rear direction X with respect to a virtual plane that is perpendicular to the front-rear direction X. The display panels 11 and 12 are positioned so as to include projection areas when the display surfaces 11a and 12a of the display panels 11 and 12 are projected in the front-rear direction X.

  In the present embodiment, the display unit 110 in the double-sided display device 100 further includes an illumination device 20 that illuminates the two display panels 11 and 12 from the back side.

  The illuminating device 20 receives light from a single light guide plate 21 provided between the two display panels 11 and 12 along the display panels 11 and 12, and an end surface (light incident surface 21c) of the light guide plate 21. And an incident light source 22. In the illumination device 20, the light beams emitted from the light source 22 on both sides of the light guide plate 21 facing the display panels 11 and 12 and incident from the end surface (light incident surface 21 c) of the light guide plate 21 are applied to the display panels 11 and 12. The light emission surfaces 21a and 21b are respectively emitted toward the surface.

  According to the present embodiment, since the two display panels 11 and 12 are provided so that the display surfaces 11a and 12a are opposed to each other, the two display panels 11 and 12 are visually recognized from both outer sides. Is possible. In addition, the light guide plate 21 includes a single light guide plate 21 provided between the two display panels 11 and 12, and a light source 22 that receives light from an end surface (light incident surface 21 c) of the light guide plate 21. Light emitting surfaces 21a, which emit light emitted from the light source 22 and incident from the end surface (light incident surface 21c) of the light guide plate 21 toward the display panels 11, 12, respectively. 21b, only one light guide plate 21 is required, and the entire double-sided display device 100 can be made thinner as compared to a conventional configuration in which single-sided display devices are simply overlapped.

  Specifically, the light source 22 is supported by a bracket 43 fixed to the main body of the display unit 110. In this example, the light source 22 is a pair of light sources 22, 22 provided on both sides in the width direction Y of the light guide plate 21 and extending along the height direction Z. In this example, the light source 22 has a plurality of light emitting diodes (LEDs) 22a (LED: Light Emitting Diodes) arranged in parallel in the height direction Z on the substrate 22b supported by the bracket 43. .

  By the way, the light from the light source 22 becomes dark as it leaves | separates from the input part (light incident surface 21c) of the light from the light source 22 of the light-guide plate 21. FIG.

  Therefore, in the present embodiment, the illuminating device 20 has a uniform or substantially uniform amount of light from the light emitting surfaces 21a and 21b on both sides of the light guide plate 21 facing the display panels 11 and 12 to the display panels 11 and 12. It is supposed to be configured.

  As a configuration in which the amount of light from the light exit surface to the display panel is uniform or substantially uniform, in the conventional one-sided display device configuration, the light guide plate on the surface opposite to the display panel By providing a transparent pattern (for example, a white dot pattern) and reflecting light incident on the light guide plate from the light source with a non-transparent pattern, the amount of light emitted from the light guide plate is uniform or substantially uniform in various places. It was like that.

  However, in the double-sided display device 100 according to the present embodiment, a non-transparent pattern (for example, white color) is provided on the surface (light emitting surface 21b, 21a) opposite to the display panel 11, 12 of the light guide plate 21 as in the past. In the case where the non-transparent pattern of the light guide plate 21 is viewed from the side where the non-transparent pattern is provided, the non-transparent pattern provided on the light guide plate 21 is visible, which hinders display. . As an improvement measure, an optical member 30 having light diffusibility is disposed between the light guide plate 21 and the display panels 11 and 12 to increase the thickness of the optical member 30 or / or, further, the light guide plate 21 and the display panel. It is conceivable that the non-transparent pattern provided on the light guide plate 21 is made difficult to see by increasing the spatial distance d3 with respect to 11 and 12, but in this case, the double-sided display device 100 is further reduced in thickness. It becomes difficult to make it.

  From this point of view, in the present embodiment, in order to make the pattern provided on the light guide plate 21 difficult to see and to further reduce the thickness of the double-sided display device 100, both sides of the light guide plate 21 facing the display panels 11 and 12 are provided. A transparent pattern 23 formed of a transparent material (for example, a transparent resin material) is provided on at least one of the light emitting surfaces 21a and 21b (the light emitting surface 21a in the example shown in FIG. 2). The transparent pattern 23 can reflect light incident on the light guide plate 21 from the light source 22.

  In the present embodiment, the double-sided display device 100 is configured such that the light incident from the light incident surface 21c of the light guide plate 21 includes a non-pattern portion region where the transparent pattern 23 of the light guide plate 21 does not exist and a pattern portion region where the transparent pattern 23 exists. Among them, the light is totally reflected in at least the non-pattern part region, and the light incident from the light incident surface 21 c guides the light guide plate 21. In the transparent pattern 23, the optical path of the guided light changes due to changes in the refractive index, light transmittance, light reflectance, etc., and the light is emitted from the display surface side (light emitting surfaces 21a and 21b). The transparent pattern 23 provided on the light guide plate 21 controls the amount and distribution of the emitted light, and plays an important role in determining the efficiency and uniformity of the light emitted toward the display panels 11 and 12. Is.

  Note that, among the components in FIG. 2, components that are not described will be described later.

  FIG. 3 is a cross-sectional view for explaining a reflection state of the light L incident on the light guide plate 21 from the light source 22. In FIG. 3, the effect / influence by the light diffusion sheet 31 in the optical member 30 is not considered. Moreover, the pattern formation part 23a is made into circular arc shape by sectional view.

  Here, in the light guide plate 21, the incident angle of the light L reflected at the interface is θi, and the transparent pattern 23 (in this example, the plurality of pattern forming portions 23 a to 23 a configuring the transparent pattern 23) does not exist. The critical angle in the region α is θα.

  As shown in FIG. 3, the light guide plate 21 guides the light L incident from the light source 22 using total reflection. Specifically, when the light L emitted from the light source 22 enters the light guide plate 21 from the light incident surface 21 c of the light guide plate 21, the criticality reaches a portion (non-pattern part region α) where the transparent pattern 23 is not applied. The light L having an incident angle θi that is equal to or greater than the angle θα is totally reflected, while the light L that has reached the portion (pattern portion region β) on which the transparent pattern 23 has been applied is the refractive index and light reflectance of the material of the pattern forming portion 23a. The optical path is changed depending on the shape and the like, and light L1 having an incident angle θi smaller than the critical angle θα is emitted to the outside (display surface side) of the light guide plate 21.

  Needless to say, “total reflection” is a phenomenon in which incident light is totally reflected without passing through the interface when light enters a medium having a high refractive index from a medium having a high refractive index. The “critical angle” is the minimum incident angle at which total reflection occurs when light enters from a medium having a large refractive index to a medium having a small refractive index, and the incident angle when the refraction angle is 90 degrees. Say. If the critical angle is θ, the refractive index of the incident medium is na, and the refractive index of the incident medium is nb, the critical angle θ can be expressed by the following equation.

θ = arcsin (na / nb)
Thus, according to the present embodiment, the transparent pattern 23 formed of a transparent material is provided on at least one of the light emitting surfaces 21a and 21b on both sides of the light guide plate 21 facing the display panels 11 and 12 side. By being provided, it is possible to adjust the amount of light emitted from each part of the light guide plate 21, and thereby, the amount of light emitted from both the light emitting surfaces 21 a and 21 b of the light guide plate 21 is adjusted at various places. Even if the double-sided display device 100 is viewed from the side where the transparent pattern 23 of the light guide plate 21 is provided, the transparent pattern 23 provided on the light guide plate 21 is difficult to see. Can do. Therefore, it is possible to effectively prevent the transparent pattern 23 from hindering display.

  The transparent material may be any material as long as it is transparent. For example, it may be a transparent resin material or a transparent glass material.

  In the present embodiment, the transparent resin material is a transparent ultraviolet curable resin material that is cured by ultraviolet rays (specifically, cured by ultraviolet rays and bonded to the light guide plate 21). The ultraviolet curable resin material may be any transparent ultraviolet curable resin material that is cured by ultraviolet rays. Examples of the ultraviolet curable resin material include, but are not limited to, urethane acrylate, acrylic resin acrylate, and epoxy acrylate.

  Thus, by using an ultraviolet curable resin material as the transparent resin material, the ultraviolet curable resin material usually has a low viscosity before being cured, so that the size of the transparent pattern 23 is further reduced. Thus, the transparent pattern 23 can be made more difficult to see, and the transparent pattern 23 can be made less likely to hinder display.

  The light guide plate 21 may be made of any material as long as it is a transparent material, and a conventionally known material can be used. The material of the light guide plate 21 may be, for example, a transparent resin material or a transparent glass material. Although it does not specifically limit as a transparent resin material, For example, an acrylic resin (typically polymethyl methacrylate resin: PMMA), a polycarbonate resin, etc. can be mentioned.

  Here, the light incident surface 21c is a side surface of the light guide plate 21 that is not directed to the display panels 11 and 12, and in this example, the light incident surface 21c and both the light emitting surfaces 21a and 21b are perpendicular or substantially perpendicular. It is said that. In this example, the light source 22 is provided such that the optical axis of the emitted light (the central axis of the light beam) is perpendicular or substantially perpendicular to the light incident surface 21c.

  Examples of the cross-sectional shape of the light guide plate 21 include a rectangular shape and a wedge shape. When the light sources 22 are provided on both sides in the width direction Y of the light guide plate 21 as in the present embodiment (when light from the pair of light sources 22 and 22 is incident from both end faces in the width direction Y of the light guide plate 21). The cross-sectional shape of the light guide plate 21 can be rectangular. In this example, the light guide plate 21 has light emission surfaces 21 a and 21 b arranged in parallel or substantially parallel to the display panel 11. Further, when the light source 22 is provided on one side in the width direction Y of the light guide plate 21 (when light from a single light source 22 enters from one end face in the width direction Y of the light guide plate 21), The cross-sectional shape can be a wedge shape (an isosceles trapezoidal shape or an isosceles triangle shape). In this case, the illuminating device 20 can make the light from the light source 22 enter from the end surface of the light guide plate 21 (the bottom surface of the light guide plate 21 having an isosceles trapezoidal shape or an isosceles triangle shape in a sectional view).

  By the way, when the transparent pattern 23 is provided on at least one of the light emitting surfaces 21a and 21b on both sides of the light guide plate 21 facing the display panels 11 and 12, it is usually provided on both the light emitting surfaces 21a and 21b. However, by applying the same transparent pattern 23 to the front and back of the light guide plate 21 (both the light emitting surfaces 21a and 21b), the amount of light emitted from the front and back can be easily balanced. Therefore, although the design is a little easier, by providing the transparent pattern 23 on both sides, the pattern forming process is doubled, while the front and back rotating method of the light guide plate 21 and the other side while protecting the patterned surface. Because of the construction of the surface, management becomes difficult. In other words, such a configuration has a very high processing cost. That is, when the transparent pattern 23 is provided on the light guide plate 21, two steps are required, that is, the step of providing the transparent pattern 23 on one light emitting surface 21a and the step of providing the other light emitting surface 21b. The processing cost for providing 23 is high. On the other hand, in order to ensure uniformity within the surface of the light guide plate 21, it is necessary to change and adjust the transparent pattern 23 within the surface of the light guide plate 21.

  Therefore, as shown in FIG. 2, the transparent pattern 23 is preferably provided only on one side of the light emitting surfaces 21 a and 21 b on both sides of the light guide plate 21 facing the display panels 11 and 12. In this example, the transparent pattern 23 is provided only on one of the light emitting surfaces 21a and 21b.

  Thus, when the transparent pattern 23 is provided on the light guide plate 21 by providing the transparent pattern 23 only on one light emitting surface (in this example, one light emitting surface 21a), the transparent pattern 23 is provided on both surfaces. Compared to the case, the number of steps for providing the transparent pattern 23 can be reduced to one, and the processing cost for providing the transparent pattern 23 can be reduced accordingly.

  Moreover, in this Embodiment, the illuminating device 20 is provided with a pair of optical members 30 and 30 each including the light-diffusion sheet 31 which has light diffusibility. The pair of optical members 30 and 30 are arranged such that the light diffusion sheet 31 is located closest to the light emitting surfaces 21a and 21b on the light emitting surfaces 21a and 21b on both sides facing the display panels 11 and 12 of the light guide plate 21, respectively. Is arranged.

  As described above, by arranging the pair of optical members 30 and 30 (specifically, the light diffusion sheets 31 and 31) on the light emitting surfaces 21 a and 21 b on both sides of the light guide plate 21, the light emitting surfaces 21 a and 21 b are separated from each other. The emitted light (for example, the light reflected from the transparent pattern 23 and emitted from the light emitting surfaces 21a and 21b) can be diffused in all directions including the direction of returning the light into the light guide plate 21, thereby guiding the transparent pattern 23. The difference in luminance between the two sides of the light guide plate 21 can be reduced when the transparent pattern 23 is provided only on one side of the light guide plate 21 as well as when provided on both sides of the light plate 21. In addition to improving the luminance uniformity in the 21 plane, it is possible to have a configuration in which there is almost no luminance difference between the front and back sides. That is, by arranging the light diffusing sheets 31 and 31 having diffusibility on the light emitting surfaces 21 a and 21 b on both sides of the light guide plate 21, even the light guide plate 21 having the transparent pattern 23 only on one side is used. It becomes possible to ensure the uniformity of the front and back.

  In the present embodiment, the optical member 30 disposed on one light emitting surface 21a and the optical member 30 disposed on the other light emitting surface 21b have the same configuration.

  As shown in FIG. 2, each of the pair of optical members 30 includes at least a light diffusion sheet 31 having light diffusibility. In this example, each of the pair of optical members 30 and 30 includes a prism sheet 32 and a reflective polarizing sheet 33 in addition to the light diffusion sheet 31.

  The pair of optical members 30 and 30 are disposed so as to cover the light emitting surfaces 21 a and 21 b of the light guide plate 21. In this example, the pair of optical members 30, 30 is formed by laminating a light diffusion sheet 31, a prism sheet 32, and a reflective polarizing sheet 33 in order from the light emitting surfaces 21 a, 21 b side of the light guide plate 21.

  The light diffusion sheet 31 has a function of diffusing light emitted from the light emission surfaces 21a and 21b, for example, by bonding a diffusion layer in which light scattering particles are dispersed and blended to the surface of a transparent base made of synthetic resin. Have That is, the light diffusing sheet 31 not only emits the light emitted from the light emitting surfaces 21a and 21b to the outside of the light guide plate 21 but also returns it to the inside of the light guide plate 21 (toward the light guide plate 21). (Reflecting) function.

  The prism sheet 32 has a function of adjusting the traveling direction of light passing through the light diffusion sheet 31.

  The reflective polarizing sheet 33 has, for example, a multilayer structure in which layers having different refractive indexes are alternately stacked, and transmits p-waves of light emitted from the light emitting surfaces 21a and 21b, and transmits s-waves. It is configured to reflect. As a result, s-waves absorbed by the polarizing plates (not shown) of the display panels 11 and 12 can be reused, and the light utilization efficiency can be increased. An example of such a reflective polarizing sheet 33 is a trade name “DBEF (registered trademark)” manufactured by Sumitomo 3M Limited.

  In the present embodiment, the formation of the transparent pattern 23 is performed by printing. By doing so, the transparent pattern 23 can be formed easily and easily.

  Here, examples of the printing method for forming the transparent pattern 23 include a screen printing method and an ink jet printing method. Among these, by adopting the ink jet printing method, fine printing can be performed, and thereby, even the pattern forming portion 23a having a size of 100 μm or less can be surely printed. A printing apparatus that performs printing by a screen printing method or an inkjet printing method and its printing operation are the same as a conventionally known printing apparatus and its printing operation except that a transparent material is used as a printing material, and the description thereof is omitted here.

  In the present embodiment, the light guide plate 21 has a thickness d1 of 4 mm or less. By making the thickness d1 of the light guide plate 21 4 mm or less, the double-sided display device 100 can be further reduced in thickness.

  In the present embodiment, the thicknesses d2 and d2 of the pair of optical members 30 and 30 are 2 mm or less, respectively. Thus, by making the thicknesses d2 and d2 of the pair of optical members 30 and 30 2 mm or less, the double-sided display device 100 can be further reduced in thickness.

  In the present embodiment, the spatial distances d3 and d3 between the light guide plate 21 and the display panels 11 and 12 are all 5 mm or less. As described above, when both the spatial distances d3 and d3 between the light guide plate 21 and the display panels 11 and 12 are set to 5 mm or less, the double-sided display device 100 can be further reduced in thickness.

  In the present embodiment, the transparent pattern 23 includes a plurality (a large number) of pattern forming portions 23a to 23a. By doing so, it is possible to partially adjust the formation area of the pattern forming portions 23a to 23a, thereby making it easy to adjust the amount of light emitted from each part of the light emitting surfaces 21a and 21b by the transparent pattern 23. can do. Specifically, the transparent pattern 23 includes a large number of pattern forming portions 23a to 23a that are independent of each other. Specifically, the transparent pattern 23 is formed so that a large number of pattern forming portions 23 a to 23 a are scattered in the light guide plate 21.

  The pattern forming portions 23a to 23a may have different sizes among the pattern forming portions 23a to 23a, or may be the same or substantially the same. The pattern forming portions 23a to 23a may have different pitches (distances between the centers of the adjacent pattern forming portions 23a and 23a) between the pattern forming portions 23a to 23a, or may be the same or substantially the same. Good. Moreover, the pattern formation parts 23a-23a may be arrange | positioned regularly and may be arrange | positioned irregularly.

(First to fourth embodiments)
The transparent pattern 23 composed of a large number of pattern forming portions 23a to 23a can be formed, for example, according to the following first to fourth embodiments.

  4 to 7 are front views schematically showing the transparent patterns 23 according to the first to fourth embodiments formed on the light guide plate 21, respectively.

  In the transparent pattern 23 according to the first embodiment to the fourth embodiment, the shape of the pattern forming portion 23a in a front view (plan view) is a circular shape (dot shape) in this example. However, the shape of the pattern forming portion 23a in plan view may be any shape, for example, an elliptical shape or a distorted circular shape. Moreover, the shape of the cross-sectional view of the pattern formation part 23a is made into the rectangular shape in the example shown in FIG. However, the cross-sectional shape of the pattern forming portion 23a may be any shape, for example, an arc shape such as a semicircular shape or a semielliptical shape.

  Here, the size of the pattern forming portion 23a is set to the size of the diameter (dot diameter) of the pattern forming portion 23a when the shape of the pattern forming portion 23a in a plan view is a circular shape (dot shape). In the case where the visual shape is a shape other than a circular shape, for example, the size of the longest distance among the linear distances from end to end of the pattern forming portion 23a can be set.

(First embodiment and second embodiment)
In the configuration of the first embodiment and the second embodiment shown in FIGS. 4 and 5, the pitch (the distance between the centers of the adjacent pattern forming portions 23 a and 23 a) is determined in each of the pattern forming portions 23 a to 23 a configuring the transparent pattern 23. ) Are the same or substantially the same (constant or substantially constant), and the size is increased as the distance from the light input portion (light incident surface 21c) from the light source 22 increases. In other words, the individual pattern forming portions 23a to 23a constituting the transparent pattern 23 according to the first embodiment and the second embodiment shown in FIGS. 4 and 5 have the same or substantially the same pitch, and the pattern The density of the forming portions 23a (the number of pattern forming portions 23a per unit area) decreases as the distance from the light input portion (light incident surface 21c) from the light source 22 increases.

  By doing so, the amount of light emitted from both the light emitting surfaces 21a and 21b can be increased as the distance from the input unit (light incident surface 21c) increases, whereby the light from the light source 22 is transmitted to the input unit (light Even if it becomes darker as it goes away from the incident surface 21c), the amount of light emitted from both the light emitting surfaces 21a and 21b can be surely made uniform or substantially uniform.

  The minimum size of each pattern formation part 23a-23a which comprises the transparent pattern 23 which concerns on 1st Embodiment shown in FIG. 4 is made larger than 300 micrometers. As described above, even if the minimum size of the pattern forming portions 23a to 23a is larger than 300 μm, the pattern forming portions 23a to 23a are made of a transparent material so that the pattern forming portions 23a to 23a are difficult to see. be able to. Therefore, it is possible to effectively prevent the transparent pattern 23 from hindering display.

  Moreover, the minimum size of each pattern formation part 23a-23a which comprises the transparent pattern 23 which concerns on 2nd Embodiment shown in FIG. 5 is 300 micrometers or less, More preferably, it is 70 micrometers or less. As described above, by setting the minimum size of the pattern forming portions 23a to 23a to 300 μm or less, the pattern forming portions 23a to 23a can be made more difficult to see, and the minimum size of the pattern forming portions 23a to 23a is set to 70 μm or less. As a result, the pattern forming portions 23a to 23a can be hardly seen, and accordingly, the pattern forming portions 23a to 23a can be made difficult to obstruct display.

(Third embodiment)
By the way, in the structure of 1st Embodiment and 2nd Embodiment, since it is necessary to make the size of the pattern formation part 23a far from the light source 22 larger than the size of the pattern formation part 23a nearer to the light source 22, it is only that. The pattern forming portion 23a far from the light source 22 is easily visually recognized.

  Therefore, in the configuration of the third embodiment shown in FIG. 6, the size is the same or substantially the same (constant or substantially constant) and the pitch (adjacent) in the individual pattern forming portions 23 a to 23 a constituting the transparent pattern 23. The distance between the centers of the matching pattern forming portions 23a and 23a) is reduced as the distance from the light input portion (light incident surface 21c) from the light source 22 increases. In other words, the individual pattern forming portions 23a to 23a constituting the transparent pattern 23 according to the third embodiment shown in FIG. 6 have the same or substantially the same size, and the density (unit area) of the pattern forming portion 23a. The number of hit pattern formation portions 23a) increases as the distance from the light input portion (light incident surface 21c) from the light source 22 increases.

  By doing so, the amount of light emitted from both the light emitting surfaces 21a and 21b can be increased as the distance from the input unit (light incident surface 21c) increases, whereby the light from the light source 22 is separated from the input unit. Even if it becomes darker, the amount of light emitted from both light emitting surfaces 21a and 21b can be made uniform or substantially uniform, and the sizes of the pattern forming portions 23a to 23a can be the same or substantially the same. Thus, regardless of the distance from the light source 22, the pattern forming portions 23a to 23a can be reduced to a constant or substantially constant size, thereby making it difficult to visually recognize the pattern forming portion 23a. For example, by making the size of the individual pattern forming portions 23a to 23a constituting the transparent pattern 23 300 μm or less, the pattern forming portions 23a to 23a can be made more difficult to see, and the size of the pattern forming portions 23a to 23a can be reduced. By setting the thickness to 70 μm or less, the pattern forming portions 23a to 23a can be hardly seen, and accordingly, the pattern forming portions 23a to 23a can be made difficult to obstruct display.

(Fourth embodiment)
By the way, each pattern formation part 23a-23a which comprises the transparent pattern 23 which concerns on 3rd Embodiment from 1st Embodiment is formed regularly. In this example, the transparent patterns 23 according to the first to third embodiments are arranged such that the rows 23b of the pattern forming portions 23a to 23a arranged along the predetermined direction (the height direction Z in this example) are in the predetermined direction. Are arranged in a plurality of rows along a direction orthogonal to the width direction (in this example, the width direction Y). Further, the transparent pattern 23 according to the first to third embodiments has a pattern forming portion 23a that configures each row between adjacent rows 23b and 23b in a direction orthogonal to a predetermined direction (in this example, the width direction Y). ˜23a are formed to be staggered.

  However, if the arrangement of the individual pattern forming portions 23a to 23a constituting the transparent pattern 23 is regular as in the configurations of the first to third embodiments, the arrangement state of the pattern forming portions 23a to 23a is It is easy to cause uneven interference. If it does so, the interference nonuniformity according to the arrangement | positioning state of pattern formation part 23a-23a will prevent a display.

  Therefore, in the present embodiment, it is preferable that the individual pattern forming portions 23a to 23a constituting the transparent pattern 23 are irregularly (randomly) formed.

In this example, in the configuration of the third embodiment shown in FIG. 6, the pattern forming portions 23a to 23a are irregularly (randomly) formed. That is, the transparent pattern 23 according to the fourth embodiment shown in FIG. The individual pattern forming portions 23a to 23a are configured to have the same or substantially the same size, and the pitch (the distance between the centers of the adjacent pattern forming portions 23a and 23a) is the light input portion from the light source 22 (light incident). In other words, the density of the pattern forming portion 23a is disorderly arranged so as to increase with increasing distance from the light input portion (light incident surface 21c) from the light source 22. .

  By doing so, it is possible to suppress the occurrence of interference unevenness according to the arrangement state of the pattern forming portions 23a to 23a, and thereby the interference unevenness according to the arrangement state of the pattern forming portions 23a to 23a is unlikely to hinder display. be able to. Further, by making the size of the pattern forming portions 23a to 23a 300 μm or less, the pattern forming portions 23a to 23a can be made more difficult to see, and by making the size of the pattern forming portions 23a to 23a 70 μm or less The formation parts 23a to 23a can be made almost invisible, and the pattern formation parts 23a to 23a can be made difficult to prevent display.

  In the first to fourth embodiments, when the light source 22 is provided only on one side in the width direction Y of the light guide plate 21, the dot diameter is increased from the light incident side toward the non-light incident side. Alternatively, the same effect can be obtained by narrowing the pitch.

(Example)
Next, an example of the double-sided display device 100 according to the present embodiment will be described below with reference to FIG.

  In this example, the visual recognition state of the pattern forming portion 23a was confirmed using the transparent pattern 23 shown in FIG. The result is shown in FIG.

  FIG. 8 is a chart showing the results of an example of the double-sided display device 100 according to the present embodiment. In the embodiment shown in FIG. 8, “◎” indicates a level at which the pattern forming portion 23a is not visible, “◯” indicates a level at which the pattern forming portion 23a is hardly visible, and “Δ” indicates that the pattern forming portion 23a appears thin. It was evaluated as a level without any hindrance.

  As shown in FIG. 8, Examples 1 and 2 in which the pattern forming portion 23a is formed by a screen printing with a dot diameter of 400 μm and 200 μm by screen printing, and the pattern forming portion 23a is 400 μm by an ultraviolet curable resin by screen printing. In Example 3 formed with a dot diameter of 3, the pattern forming portion 23a looks thin, but at a level that does not impede practical use. In Examples 4 and 5 in which the pattern forming portion 23a was formed by screen printing with a UV curable resin with a dot diameter of 300 μm and 100 μm, the pattern forming portion 23a was almost invisible. Further, in Example 6 in which the pattern forming portion 23a was formed with an ultraviolet curable resin with a dot diameter of 70 μm by ink jet printing, the pattern forming portion 23a was at a level where it could not be seen.

  The present invention is not limited to the embodiment described above, and can be implemented in various other forms. Therefore, such an embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is shown by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Double-sided display apparatus 11 Display panel 110 Display part 11a Display surface 12 Display panel 120 Stand part 12a Display surface 20 Illumination device 21 Light guide plate 21a Light emission surface 21b Light emission surface 21c Light incident surface (end surface)
22 light source 22a light emitting diode 22b substrate 23 transparent pattern 23a pattern forming unit 30 optical member 31 light diffusing sheet 32 prism sheet 33 reflective polarizing sheet 40 holding unit 41 first holding unit 41a fixing unit 41b holding unit 42 second holding unit 43 bracket SP spacer X Front-rear direction Y Width direction Z Height direction d1 Light guide plate thickness d2 Optical member thickness d3 Spatial distance α Non-pattern part region β Pattern part region θ Critical angle θi Incident angle θα Critical angle

Claims (13)

Two display panels provided so that their display surfaces are in conflict with each other;
A single light guide plate provided between the two display panels;
A light source for entering light from an end face of the light guide plate,
Both sides of the light guide plate facing the display panel are light emission surfaces that emit light emitted from the light source and incident from the end surface of the light guide plate toward the display panels, respectively.
A double-sided display device, characterized in that the light amount from the light emitting surfaces on both sides of the light guide plate facing the display panel is uniform or substantially uniform. Two display panels provided so that their display surfaces are in conflict with each other;
A single light guide plate provided between the two display panels;
A light source for entering light from an end face of the light guide plate,
Both sides of the light guide plate facing the display panel are light emission surfaces that emit light emitted from the light source and incident from the end surface of the light guide plate toward the display panels, respectively.
A double-sided display device, wherein a transparent pattern made of a transparent material is provided on at least one of the light emitting surfaces on both sides of the light guide plate facing the display panel. The double-sided display device according to claim 2,
The double-sided display device, wherein the transparent material is a transparent ultraviolet curable resin material that is cured by ultraviolet rays.
The double-sided display device according to claim 2 or 3,
The transparent pattern is provided only on one side of the light emitting surfaces on both sides of the light guide plate facing the display panel, and on the light emitting surfaces on both sides of the light guide plate facing the display panel. A double-sided display device in which light diffusing sheets having light diffusibility are respectively disposed. A double-sided display device according to any one of claims 2 to 4,
The transparent pattern comprises a plurality of pattern forming portions,
The double-sided display device characterized in that in each of the pattern forming portions constituting the transparent pattern, the size is the same or substantially the same, and the pitch is reduced as the distance from the light input portion from the light source is increased. . A double-sided display device according to any one of claims 2 to 5,
The transparent pattern comprises a plurality of pattern forming portions,
The double-sided display device, wherein each of the pattern forming portions constituting the transparent pattern is irregularly formed. The double-sided display device according to claim 5 or 6,
A double-sided display device, wherein the size of each of the pattern forming portions constituting the transparent pattern is 300 μm or less, more preferably 70 μm or less. A double-sided display device according to any one of claims 2 to 7,
The double-sided display device is characterized in that the transparent pattern is formed by printing. A double-sided display device according to any one of claims 2 to 8,
The double-sided display device, wherein the light guide plate has a thickness of 4 mm or less. A double-sided display device according to any one of claims 2 to 9,
A pair of optical members each including a light diffusing sheet located at a position closest to the light emitting surface and having a light diffusing property is disposed on each of the light emitting surfaces on both sides of the light guide plate facing the display panel. ,
Each of the pair of optical members has a thickness of 2 mm or less. A double-sided display device according to any one of claims 2 to 10,
A double-sided display device, wherein a spatial distance between the light guide plate and the display panel is 5 mm or less. It is provided in the double-sided display device according to any one of claims 2 to 11,
The light source and the light guide plate, each side of the light guide plate facing the display panel side is emitted from the light source and incident from the end surface of the light guide plate toward each display panel, respectively. A light emitting surface to be emitted, and at least one of the light emitting surfaces on both sides facing the display panel of the light guide plate is provided with a transparent pattern formed of a transparent material. A lighting device. It is provided in the double-sided display device according to any one of claims 2 to 11 or the illumination device according to claim 12.
The surfaces on both sides facing the display panel are light emitting surfaces that emit light emitted from the light source and incident from the end surface toward the display panels, and the both sides facing the display panel are A light guide plate characterized in that a transparent pattern made of a transparent material is provided on at least one of the light exit surfaces.

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