JP2005093147A - Lighting system and display device equipped with the same, and portable electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system suitably used as a backlight for a display device equipped with two display panels arranged at opposite sides and portable electronic equipment, and a display device and portable electronic equipment equipped with the same. <P>SOLUTION: The lighting system is provided with a light source 1, a first light guide plate 10 receiving light emitted from the light source 1 and emitting part of it in a first direction, and a second light guide plate 20 emitting another part of the light in a second direction different from the first direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an illumination device, and more particularly to an illumination device that emits light in two directions. The present invention also relates to a display device and a portable electronic device provided with such a lighting device.

  In recent years, portable phones have been widely used, and a foldable type that can fold a phone body has become mainstream. In particular, a two-screen type having a main display surface for displaying main information and a sub-display surface for displaying auxiliary information is gaining popularity due to its convenience. The sub display surface is arranged on the side opposite to the main display surface so that the sub display surface can be viewed in a folded state, and displays the reception state of the radio wave, the remaining battery level, and the like. A two-screen type portable telephone is disclosed in, for example, Patent Document 1.

  In a two-screen type mobile phone, it is necessary to irradiate both a liquid crystal panel for a main display surface (referred to as a “main panel”) and a liquid crystal panel for a sub display surface (referred to as a “subpanel”). Therefore, an illuminating device that can emit light in two directions is used.

  In recent years, the body is required to be thin so that the thickness does not matter even when folded, and the lighting device is also required to be thin. Therefore, use of an illumination device (backlight) 600 as shown in FIGS. 8A and 8B has been proposed.

  The illuminating device 600 has a configuration in which two edge light type backlights each having a light source disposed on an end surface of a light guide plate are stacked. Specifically, the illumination device 600 includes a backlight 600A for a main panel and a backlight 600B for a sub panel.

  The main panel backlight 600A includes a first light source 601 and a first light guide plate 610 that emits light from the first light source 601 to the main panel side. The sub-panel backlight 600B includes a second light source 602 and a second light guide plate 620 that emits light from the second light source 602 to the sub-panel side.

  Each of the first light source 601 and the second light source 602 is a plurality of light emitting diodes (LEDs). The first light source 601 and the second light source 602 are disposed so as to be opposite to each other with respect to the first light guide plate 610 and the second light guide plate 620. The second light source 602 is provided on one flexible wiring board 603.

  In general, an edge light type backlight can be easily reduced in thickness as compared with other types of backlights, and thus a configuration in which two edge light type backlights are stacked as in the lighting device 600 is used. By this, it can suppress that an illuminating device becomes thick.

In addition, as another method for realizing a reduction in thickness, a method of emitting light from both the main surface and the back surface of a single light guide plate has been studied.
JP 2001-136247 A

  However, in the illuminating device 600 shown in FIGS. 8A and 8B, the first light source 601 and the second light source 602 provided on the opposite sides are provided on one flexible wiring board 603. Therefore, it is necessary to enlarge the flexible wiring board 603 by an amount equivalent to the length of the wiring. Since the flexible wiring board 603 is a member whose quantity that can be taken from the base material affects the manufacturing cost, the manufacturing cost increases when the flexible wiring board 603 increases.

  In addition, in the method using a single light guide plate, it is difficult to appropriately control the amount of light emitted from the main surface of the light guide plate and the amount of light emitted from the back surface, and the light from the light source is efficiently used. It becomes the design which cannot be used.

  The present invention has been made in view of the above problems, a display device including two display panels arranged on opposite sides of each other, and an illumination device that is suitably used as a backlight of a portable electronic device, and the same It is an object of the present invention to provide a display device and a portable electronic device.

  An illumination device according to the present invention includes a light source, a first light guide plate that receives light emitted from the light source and emits a part thereof in a first direction, and another part different from the first direction. A second light guide plate that emits light in the direction of 2, wherein the first light guide plate intersects the first incident end surface that receives light emitted from the light source and the first incident end surface. A first emission main surface that emits part of light incident from the first incident end surface in the first direction; a first opposing surface that faces the first emission main surface; the first emission main surface; An exit end face that faces the first entrance end face through the first facing face and emits another part of the light incident from the first entrance end face, and the second light guide plate includes the first light guide plate. A first portion disposed so as to face the emission end face of the light guide plate, and a first facing face of the first light guide plate; And a second part that is continuous with the first part. The first part includes a second incident end face that receives light emitted from the emission end face of the first light guide plate, and the second part. A conversion surface that changes a traveling direction of light incident from the incident end surface, and at least a part of the light emitted from the emitting end surface is introduced into the second portion while changing the traveling direction, and the second portion Is arranged on the opposite side to the side facing the first facing surface and emits at least part of the light introduced by the first part in the second direction, and the second A second facing surface disposed on the side facing the first facing surface and facing the second emission main surface, and further, the first light guide plate substantially extends from the first incident end surface toward the emitting end surface. The thickness of the second light guide plate is reduced. Have substantially the thickness becomes thinner shape with increasing distance from said first portion, said objective is met.

  In a preferred embodiment, a first reflecting member provided between the first facing surface and the second facing surface is provided.

  In a preferred embodiment, a second reflecting member is provided so as to cover the conversion surface of the first portion.

  In a preferred embodiment, a chassis for holding the first light guide plate and the second light guide plate is provided, and the chassis is made of a reflective material.

  Another illumination device according to the present invention includes a light source, a first light guide unit that receives light emitted from the light source and emits a part thereof in a first direction, and another part in the first direction. And a second light guide part that emits light in a second direction different from each other, wherein the first light guide part intersects the first incident end face and a first incident end face that receives light emitted from the light source, A first emission main surface that emits part of light incident from the first incident end surface in the first direction; a first opposing surface that faces the first emission main surface; the first emission main surface; An exit end face that faces the first entrance end face through the first facing face and emits another part of the light incident from the first entrance end face, and the second light guide section includes the first light guide section. The second light guide unit is disposed so as to face the first facing surface of the light guide plate, and is disposed on a side opposite to the side facing the first facing surface. A second emission main surface that emits at least part of the light introduced into the second direction, and a second opposite surface that is disposed on the side facing the first opposite surface and faces the second emission main surface The lighting device further includes a third light guide portion disposed so as to oppose the emission end face of the first light guide portion, and the third light guide portion includes the first light guide portion. A second incident end face that receives light emitted from the emission end face of the optical plate; and a conversion surface that changes a traveling direction of light incident from the second incident end face, and at least part of the light emitted from the emission end face The traveling direction is changed and introduced into the second light guide unit, and the second light guide unit and the third light guide unit are integrally formed so as to be continuous with each other, thereby achieving the above object. The

  In a preferred embodiment, a first reflecting member provided between the first facing surface and the second facing surface is provided.

  In a preferred embodiment, a second reflecting member is provided so as to cover at least the conversion surface of the third light guide.

  In a preferred embodiment, a chassis for holding the first light guide part, the second light guide part, and the third light guide part is provided, and the chassis is made of a reflective material.

  In a preferred embodiment, the conversion surface has a plurality of surfaces that are not parallel to each other.

  In a preferred embodiment, the plurality of surfaces of the conversion surface are approximately 90 ° with respect to the first surface and the first surface that form an angle of approximately 45 ° with respect to the second incident end surface. A second surface forming an angle is included.

  In a preferred embodiment, the plurality of surfaces of the conversion surface are three or more surfaces including a surface that forms an angle of less than 45 ° with the second incident end surface.

  Still another illumination device according to the present invention includes a light source, a first light guide plate that receives light emitted from the light source and emits a part of the light in a first direction, and another part of the light in the first direction. A second light guide plate that emits in a different second direction, wherein the first light guide plate is disposed on the light source side of the first portion and the first portion. A first incident end face that receives light emitted from the light source, and is disposed on the opposite side of the light source and includes a second part that is continuous with the first part. An exit end face facing part of the first entrance end face and emitting a part of the light incident from the first entrance end face, and the second part is the first entrance end face of the first part. A first emission main surface that emits another part of the light incident from the first direction in the first direction, and a first pair that faces the first emission main surface The second light guide plate is disposed so as to face the first facing surface of the second portion, and receives the light emitted from the emitting end surface of the first portion. Two incident end faces and a second emission main face that is arranged on the opposite side of the side facing the first opposing face and emits at least part of light incident from the second incident end face in the second direction; And a second facing surface disposed on the side facing the first facing surface and facing the second emission main surface, thereby achieving the above object.

  In a preferred embodiment, a reflection member is further provided between the first facing surface and the second facing surface.

  In a preferred embodiment, a chassis for holding the first light guide plate and the second light guide plate is provided, and the chassis is made of a reflective material.

  In a preferred embodiment, the light source is at least one light emitting diode.

  The amount of light emitted in the second direction is preferably 1/20 or more of the amount of light emitted in the first direction.

  The display device according to the present invention includes an illumination device having the above configuration, a first display panel that modulates light emitted from the illumination device in the first direction, and the first display panel with respect to the illumination device. And a second display panel that is arranged on the opposite side and modulates the light emitted from the lighting device in the second direction, thereby achieving the above object.

  A portable electronic device according to the present invention includes a lighting device having the above configuration, a first display panel that modulates light emitted from the lighting device in the first direction, and the first display panel with respect to the lighting device. A second display panel that modulates the light emitted from the lighting device in the second direction, and a housing that houses the lighting device, the first display panel, and the second display panel Thus, the above object is achieved.

  In a preferred embodiment, the housing includes a display unit that houses the lighting device, the first display panel, and the second display panel, an operation unit provided with at least operation keys, the display unit, and the display unit. It has a connection part which connects an operation part, and it can be folded up by the above-mentioned connection part.

  In a preferred embodiment, the first display panel and the second display panel are liquid crystal display panels that perform display in a normally white mode, and one of the first display panel and the second display panel is information. Is displayed, the other is supplied with a signal for black display.

  According to the present invention, there are provided a display device including two display panels disposed on opposite sides of each other, a lighting device suitably used as a backlight of a portable electronic device, a display device including the display device, and a portable electronic device. Provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

(Embodiment 1)
The illuminating device 100 in this embodiment is demonstrated referring FIG. 1 (a), (b) and FIG. FIG. 1A and FIG. 2 schematically show a cross-sectional configuration of the illumination device 100, and FIG. 1B shows a planar configuration of the illumination device 100. In FIG. 1 (b) and FIG. 2, some of the components shown in FIG. 1 (a) are omitted for easy viewing of the drawings.

  The illuminating device 100 receives the light source 1, the light emitted from the light source 1, and emits a part of the first light guide plate 10 in the first direction, and the second part different from the first direction in the second direction. The 2nd light-guide plate 20 radiate | emitted in the direction of this is provided. The first light guide plate 10 and the second light guide plate 20 are held by a chassis 30.

  In this embodiment, the light source 1 is six LEDs (light emitting diodes; for example, 1 mm in height), and is mounted on the flexible wiring board 2. The light source 1 is not limited to an LED, and a cold cathode tube (CCFT) or the like may be used.

  The first light guide plate 10 includes a first incident end surface 10a disposed on the light source 1 side, a first emission main surface 10b intersecting the first incident end surface 10a, and a first opposed surface facing the first emission main surface 10b. 10c, and an exit end face 10d facing the first entrance end face 10a via the first exit main face 10b and the first facing face 10c.

  The first incident end face 10a receives the light emitted from the light source 1, and the first outgoing main face 10b emits a part of the light incident from the first incident end face 10a in the first direction. The exit end face 10d emits another part of the light incident from the first entrance end face 10a.

  The second light guide plate 20 is arranged so as to face the first portion 20A arranged to face the emission end face 10d of the first light guide plate 10 and the facing surface 10c of the first light guide plate 10. It has the 2nd part 20B which follows the part 20A.

  The first portion 20A has a second incident end face 20a that receives light emitted from the emission end face 10d of the first light guide plate 10, and a conversion surface 20b that changes the traveling direction of the light incident from the second incident end face 20a. The first portion 20A has a function of introducing at least a part of the light emitted from the emission end face 10d into the second portion 20B while changing the traveling direction.

  In the present embodiment, the conversion surface 20b of the first portion 20A has a first surface 20b1 and a second surface 20b2 that are not parallel to each other. The first surface 20b1 forms an angle of approximately 45 ° with respect to the second incident end surface 20a, and the second surface 20b2 forms an angle of approximately 90 ° with respect to the first surface 20a.

  The second portion 20B has a second emission main surface 20c disposed on the side opposite to the side facing the first facing surface 10c. The second emission main surface 20c emits at least part of the light introduced by the first portion 20A in the second direction. The second portion 20B is also disposed on the side facing the first facing surface 10c, and also has a second facing surface 20d facing the second emission main surface 20c.

  As shown in FIGS. 1A and 2, the first light guide plate 10 has a shape that becomes substantially thinner from the first incident end surface 10 a toward the output end surface 10 d, and the second light guide plate 20. The second portion 20B has a shape in which the thickness is substantially reduced as the distance from the first portion 20A increases. That is, the first light guide plate 10 and the second portion 20B of the second light guide plate 20 both have a wedge shape, and the directions in which the thickness decreases are substantially opposite to each other.

  In the illuminating device 100 having the above structure, the light emitted from the light source 1 and entering the first light guide plate 10 through the first incident end face 10a, as shown in FIG. Propagating toward the exit end face 10d while repeating total reflection with the exit main surface 10b. Part of the light propagating in the first light guide plate 10 is transmitted from the first emission main surface 10b to the first by the light distribution regulating structure provided on at least one of the first emission main surface 10b and the first facing surface 10c. The light is emitted in the direction.

  As the light distribution regulating structure, the same type as the light distribution regulating structure used for a known light guide plate can be used. For example, a plurality of prisms 11 formed on the first emission main surface 10b as shown in FIG. 3A and a plurality of lenses 12 formed on the first emission main surface 10b as shown in FIG. 3B. Can be used. Alternatively, instead of the prism 11 and the lens 12, a fine uneven structure (referred to as “texture”) may be formed on the first emission main surface 10b.

  However, the light distribution restriction structure provided in the first light guide plate 10 is different from the conventional light distribution restriction structure of the light guide plate in that only a part of the light propagating inside the light guide plate is used. In the conventional light guide plate, the light distribution regulating structure is ideally designed so that almost all the light propagating inside the light guide plate is emitted from the emission main surface, whereas the first light guide of the illumination device 100 is designed. In the optical plate 10, the light distribution regulating structure is designed so that only a part of the light propagating through the first light guide plate 10 is emitted from the first emission main surface 10b so that a predetermined amount of light reaches the emission end face 10d. Has been. For example, the arrangement pitch of unit elements (prisms and lenses described above) constituting the light distribution regulating structure is changed, or the structure of individual unit elements is changed (change in prism angle, lens size, etc.). Thus, the amount of light emitted from the first emission main surface 10b can be changed, and thereby a predetermined amount of light can reach the emission end surface 10d.

  Of the light propagating in the first light guide plate 10, the light that has reached the emission end surface 10 d without being emitted from the first emission main surface 10 b, as shown in FIG. 2, is emitted from the emission end surface 10 d to the second light guide plate 20. The light is emitted toward the first portion 20A. The light emitted from the exit end face 10d and entering the first portion 20A of the second light guide plate 20 from the second entrance end face 20a is transmitted by the first face 20b1 and / or the second face 20b2 as the conversion face 20b. It is reflected and the direction of travel is changed and introduced into the second portion 20B.

  The light introduced into the second portion 20B propagates inside the second portion 20B while repeating total reflection on the second emission main surface 20c and the second facing surface 20d. At least part of the light propagating in the second portion 20B is secondly transmitted from the second emission main surface 20c by the light distribution regulating structure provided on at least one of the second emission main surface 20c and the second opposing surface 20d. It is emitted in the direction of. As the light distribution restriction structure provided in the second portion 20B, the same type of light distribution restriction structure as that used for a known light guide plate can be used as in the first light guide plate 10 described above. However, the light distribution regulating structure provided in the second portion 20B emits almost all of the light propagating through the second portion 20B from the second emission main surface 20c from the viewpoint of increasing the light use efficiency. It is preferable that it is designed.

  As described above, the lighting device 100 can emit light in two directions. In the illumination device 100 according to the present invention, light emitted from the emission end face 10d of the first light guide plate 10 is incident on the second light guide plate 20, and the second light guide plate 20 performs illumination using the light. Therefore, there is no need to provide light sources on both sides of the lighting device, and there is no need to route the flexible wiring board. Therefore, it is possible to reduce the size of the flexible wiring board and suppress an increase in manufacturing cost.

  In general, when a point light source such as an LED is used instead of a linear light source such as CCFT as the light source, light with low uniformity reflecting the arrangement of the point light sources is incident on the light guide plate, and thus uneven brightness is caused. May occur. However, in the lighting device 100, even if a point light source such as an LED is used as the light source 1, the light introduced into the second portion 20 </ b> B of the second light guide plate 20 propagates through the first light guide plate 10. Since the degree of uniformity is high, uniform illumination can be performed by the second light guide plate 20B.

  In the illuminating device 100, in order to introduce the light from the emission end face 10d of the first light guide plate 10 into the second portion 20B of the second light guide plate 20, the traveling direction of the light is converted by the first portion 20A. . Here, in other words, the first light guide plate 10 is a first light guide portion, and the second portion 20B of the second light guide plate 20 is a second light guide portion. The first portion 20A of the second light guide plate 20 is It can be said that it is a third light guide part for guiding a part of light emitted from one light guide part to the second light guide part while changing the traveling direction. In the lighting device 100, the first portion 20A and the second portion 20B of the second light guide plate 20 are continuous, in other words, the third light guide is continuously integrated with the second light guide. Therefore, it is possible to introduce light into the second light guide section (second portion 20B) simply and efficiently, rather than providing a separate member for changing the traveling direction.

  Furthermore, in this embodiment, both the 1st light guide plate 10 and the 2nd part 20B of the 2nd light guide plate 20 have a wedge shape, and the 1st light guide plate 10 is from 1st incident end surface 10a. The thickness becomes substantially thinner toward the emission end face 10d, and the second portion 20B of the second light guide plate 20 becomes substantially thinner as the distance from the first portion 20A increases. Therefore, the thickness of the entire lighting device can be made thinner than when two parallel plate type light guide plates are used, and a further reduction in thickness can be realized. Since the first light guide plate 10 is provided with a light distribution regulating structure (for example, the prism 11 and the lens 12 shown in FIGS. 3A and 3B), the thickness of the first light guide plate 10 is strictly set. May not monotonously decrease from the first incident end face 10a toward the outgoing end face 10d, but when an area sufficiently larger than the unit structure of the light distribution regulating structure is considered, the average thickness is different from one end side. If the shape is gradually thinned toward the end side, that is, if the shape is substantially thinned from the one end side toward the other end side, the effect of thinning can be obtained.

  As shown in FIGS. 1A and 2, when the reflecting member 3 is provided between the first facing surface 10 c and the second facing surface 20 d, the inside of the first light guide plate 10 or the second light guide plate 20. Can be prevented from leaking to the outside from other than the first emission main surface 10b and the second emission main surface 20c, and the light utilization efficiency can be improved. The reflecting member 3 is, for example, a reflecting sheet formed from a material having a high light reflectance. One reflective sheet having a sufficiently high reflectance on both sides may be used, or two reflective sheets may be used as necessary. By using two reflective sheets, light leakage to the outside can be more reliably suppressed.

  Further, as shown in FIG. 1A, when the reflection member 4 is provided so as to cover the conversion surface 20b of the first portion 20A of the second light guide plate 20, the occurrence of light leakage from the conversion surface 20b is suppressed. , Light utilization efficiency can be improved. As the reflection member 4, the same thing as the above-mentioned reflection member 3 can be used. The same effect can be obtained by forming the chassis 30 from a reflective material (for example, white high-reflective grade polycarbonate or polyphenylene sulfide) instead of providing the reflective member 4 covering the conversion surface 20b.

  In the present embodiment, the conversion surface 20b has a first surface 20b1 that forms an angle of approximately 45 ° with respect to the second incident end surface 20a, and a first surface that forms an angle of approximately 90 ° with respect to the first surface 20a. Although the case where it comprised from 2 surface 20b2 was illustrated, the structure of the conversion surface 20b is not limited to this. For example, there are four surfaces 20b1 ′, 20b2 ′, 20b3 ′, and 20b4 ′ including a surface 20b1 ′ that forms an angle of less than 45 ° with respect to the second incident end surface 20a, such as a conversion surface 20b ′ illustrated in FIG. May be. The smaller the angle formed with the second incident end face 20a by the surface that first receives light incident from the second incident end face 20a, the more light that satisfies the total reflection condition, and the more the traveling direction of the light can be changed. it can. Therefore, from the viewpoint of ease of manufacture, it is preferable to form the conversion surface from a relatively small number of surfaces as shown in FIG. 1A, and from the viewpoint of light utilization efficiency, it is shown in FIG. Thus, it is preferable that the conversion surface is composed of a relatively large number of surfaces including a surface that forms a relatively small angle with respect to the second incident end surface 20a.

  The lighting device 100 described above can be manufactured using a known method. For example, the 1st light-guide plate 10 and the 2nd light-guide plate 20 can be manufactured using a well-known method as a manufacturing method of a light-guide plate. The light distribution regulating structure of the first light guide plate 10 can be designed by simulation such as ray tracing.

(Embodiment 2)
The illumination device 200 in the present embodiment will be described with reference to FIG. FIG. 5 schematically shows a cross-sectional configuration of the illumination device 200.

  The illuminating device 200 receives the light source 1, the light emitted from the light source 1, and emits a part of the light in the first direction, and the other part of the first light guide plate 40 is different from the first direction. The 2nd light-guide plate 50 radiate | emitted in the direction of this is provided. The first light guide plate 40 and the second light guide plate 50 are held by, for example, a chassis. Here, the light source 1 is a plurality of LEDs, and is mounted on a flexible wiring board (not shown). Of course, another point light source may be used, or a cold cathode tube (CCFT) may be used.

  The first light guide plate 40 has a first portion 40A disposed on the light source 1 side and a second portion that is disposed on the opposite side of the light source 1 with respect to the first portion 40A and is continuous with the first portion 40A. Part 40B.

  The first portion 40A has a first incident end face 40a disposed on the light source 1 side and an emission end face 40b facing a part of the first incident end face 40a. The first incident end face 40a receives the light emitted from the light source 1, and the outgoing end face 40b emits a part of the light incident from the first incident end face 40a.

  The second portion 40B includes a first emission main surface 40c that emits another part of the light incident from the first incident end surface 40a of the first portion 40A in the first direction, and a first emission main surface 40c. It has the 1st opposing surface 40d which opposes.

  The second light guide plate 50 is disposed so as to face the first facing surface 40d of the second portion 40B. The second light guide plate 50 is disposed on the opposite side to the second incident end surface 50a disposed to face the emission end surface 40b of the first portion 40A and the side facing the first facing surface 40d. The main surface 50b has an emission main surface 50b and a second counter surface 50c that is disposed on the side facing the first counter surface 40d and that opposes the second main output surface 50b. The second incident end face 50a receives the light emitted from the emission end face 40b of the first portion 40A, and the second emission main face 50b passes at least part of the light incident from the second incident end face 50a in the second direction. Exit.

  In the illumination device 200 having the above structure, the light emitted from the light source 1 and incident into the first portion 40A of the first light guide plate 40 via the first incident end face 40a is, as shown in FIG. After propagating the distance (the length of the first portion 40A), a part thereof is introduced into the second portion 40B. The light introduced into the second portion 40B propagates while repeating total reflection on the first facing surface 40d and the first emission main surface 40c. At least part of the light propagating through the second portion 40B is transmitted from the first output main surface 40c to the first light distribution restriction structure provided on at least one of the first output main surface 40c and the first facing surface 40d. The light is emitted in the direction. As the light distribution regulating structure, the same type as the light distribution regulating structure used for a known light guide plate can be used.

  After the light propagating through the first portion 40A of the first light guide plate 40, the light reaching the output end surface 40b is directed from the output end surface 40b toward the second incident end surface 50a of the second light guide plate 50 as shown in FIG. Are emitted. The light introduced into the second light guide plate 50 from the second incident end face 20a propagates through the second light guide plate 50 while repeating total reflection at the second emission main surface 50b and the second facing surface 50c. At least part of the light propagating in the second light guide plate 50 is secondly transmitted from the second output main surface 50b by the light distribution regulating structure provided on at least one of the second output main surface 50b and the second facing surface 50c. It is emitted in the direction of. As the light distribution restriction structure provided in the second light guide plate 50, the same type of light distribution restriction structure as that used for a known light guide plate can be used as in the first light guide plate 40 described above.

  As described above, the lighting device 200 can emit light in two directions. In the illumination device 200 according to the present invention, light emitted from the emission end face 40b of the first portion 40A of the first light guide plate 40 is incident on the second light guide plate 50, and the second light guide plate 50 uses the light to illuminate. Do. Therefore, there is no need to provide light sources on both sides of the lighting device, and there is no need to route the flexible wiring board. Therefore, it is possible to reduce the size of the flexible wiring board and suppress an increase in manufacturing cost.

  Furthermore, in the illumination device 200 according to the present embodiment, the first light guide plate 40 includes the first portion 40A on the light source 1 side, and thus the second portion 40B of the first light guide plate 40 and the second light guide plate 50. In any of the cases, light having a high degree of uniformity by being propagated through the first portion 40A is introduced. Therefore, even if a point light source such as an LED is used as the light source 1, uniform light can be emitted from both the second portion 40 </ b> B and the second light guide plate 50.

  As shown in FIG. 5, when the reflecting member 3 is provided between the first facing surface 40d and the second facing surface 50c, the light propagating in the first light guide plate 40 and the second light guide plate 50 is the first. It is possible to suppress leakage outside the first emission main surface 40c and the second emission main surface 50b, and to improve the light utilization efficiency. The reflecting member 3 is, for example, a reflecting sheet formed from a material having a high light reflectance. One reflective sheet having a sufficiently high reflectance on both sides may be used, or two reflective sheets may be used as necessary. As part of the enhancement of the performance of mobile phones, the brightness of the display screen is also increasing, and it is assumed that very strong light is emitted from the light source 1, but by using two reflection sheets, Light leakage to the can be more reliably suppressed. Moreover, light leakage to the outside can also be suppressed by forming the chassis that holds the first light guide plate 40 and the second light guide plate 50 from a reflective material (for example, white high reflection grade polycarbonate or polyphenylene sulfide). .

  The illumination device 200 described above can also be manufactured using a known method. For example, the 1st light guide plate 40 and the 2nd light guide plate 50 can be manufactured using a well-known method as a manufacturing method of a light guide plate.

(Embodiment 3)
As described above, since the lighting device according to the present invention can be thinned at low cost, it is suitably used as a display device having two display panels arranged on opposite sides or a backlight of a portable electronic device. Used.

  However, when each of the two light guide plates illuminates the display panel, the light amount emitted from the second light guide plate in the second direction is the light amount emitted from the first light guide plate in the first direction. It is preferable that it is 1/20 or more. Since the display panel is an element having a low light transmittance of itself, the second amount of light emitted in the second direction is less than 1/20 of the amount of light emitted in the first direction. This is because the display using the light emitted in the direction may not be suitably performed. In particular, since the liquid crystal display panel typically includes a pair of polarizing plates as components, the light transmittance is generally as low as 1 to 10%.

  For example, when the size, transmittance, and desired luminance of the first display panel that receives light from the first light guide plate and the second display panel that receives light from the second light guide plate are set as shown in Table 1 below think of.

  The ratio of the amount of light emitted from the second light guide plate to the amount of light emitted from the first light guide plate is determined by the area ratio of the display panel and the brightness per unit area of the light guide plate (the desired brightness of the display panel). In this case, the light quantity ratio is {(1 × 1) / (2 × 2)} × {(50 / 0.05) / ( 200 / 0.05)} = 1 / 16≈1 / 20.

  Hereinafter, a foldable portable telephone 300 including the illumination device according to the present invention will be described with reference to FIGS. 6 and 7. FIGS. 6A and 6B are diagrams showing a folded state, in which FIG. 6A is a side view and FIG. 6B is a front view. FIGS. 7A, 7B, and 7C are views showing the opened state, where FIG. 7A is a side view, FIG. 7B is a front view, and FIG. 7C is a rear view.

  The portable phone 300 is a so-called two-screen type portable phone having a main display surface 60A for displaying main information and a sub display surface 60B for displaying auxiliary information. On the sub display surface 60B, for example, the reception state of the radio wave and the remaining battery level are displayed.

  The mobile phone 300 includes a lighting device according to the present invention (for example, the lighting device 100 shown in FIG. 1 or the lighting device 200 shown in FIG. 5), and a first display panel (which modulates light emitted from the lighting device in a first direction). For example, a liquid crystal display panel) 61, a second display panel (for example, a liquid crystal display panel) 62 that modulates light emitted from the lighting device in the second direction, a lighting device, the first display panel 61, and the second display panel 62 And a housing for housing. Although not shown here, the lighting device is provided between the first display panel 61 and the second display panel 62. Therefore, the second display panel 62 is disposed on the side opposite to the first display panel 61 with respect to the lighting device.

  The housing includes a lighting device, a display unit 60 that houses the first display panel 61 and the second display panel 62, an operation unit 70 provided with operation keys 71, and a connection that connects the display unit 60 and the operation unit 70. Part (for example, hinge) 80, and can be folded at the connecting part 80.

  Since the mobile phone 300 includes the illumination device according to the present invention as a backlight, the mobile phone 300 can be thinned while suppressing an increase in manufacturing cost.

  When the first display panel 61 and the second display panel 62 are liquid crystal display panels that perform display in a normally white mode, one of the first display panel 61 and the second display panel 62 displays information. In some cases, it is preferable to supply a signal for performing black display to the other side. By doing so, it is possible to prevent the display surface opposite to the display surface being observed from shining, and it can be suitably used as a mobile phone.

  According to the present invention, there are provided a display device including two display panels disposed on opposite sides of each other, a lighting device suitably used as a backlight of a portable electronic device, a display device including the display device, and a portable electronic device. Provided.

  The present invention is particularly preferably used for a so-called two-screen type mobile phone.

(A) And (b) is a figure which shows typically the illuminating device 100 by this invention, (a) is sectional drawing, (b) is a top view. It is sectional drawing which shows typically the illuminating device 100 by this invention. (A) And (b) is a figure which shows the example of the orientation control structure provided in a light-guide plate. It is a figure which shows the other aspect of the conversion surface which a 2nd light-guide plate has. It is sectional drawing which shows typically the other illuminating device 200 by this invention. (A) And (b) is a figure which shows typically the folded state of the portable telephone 300 by this invention, (a) is a side view, (b) is a front view. (A), (b) and (c) is a figure which shows the open state of the portable telephone 300 by this invention, (a) is a side view, (b) is a front view, (c) is a rear view. It is. (A) And (b) is a figure which shows the conventional illuminating device 600 typically, (a) is sectional drawing, (b) is a top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 2 Flexible wiring board 3, 4 Reflective member 10 1st light guide plate 10a 1st entrance end surface 10b 1st output main surface 10c 1st opposing surface 10d Output end surface 11 Prism 12 Lens 20 2nd light guide plate 20A 1st part 20B 2nd part 20a 2nd entrance end face 20b, 20b 'Conversion surface 20c 2nd output main surface 20d 2nd opposing surface 30 Chassis 40 1st light guide plate 40A 1st part 40B 2nd part 40a 1st entrance end face 40b Output End surface 40c First emission main surface 40d First opposed surface 50 Second light guide plate 50a Second incident end surface 50b Second emitted main surface 50c Second opposed surface 60 Display unit 60A Main display surface 60B Sub display surface 61 First display panel 62 Second display panel 70 Operation unit 71 Operation key 80 Connection unit 100, 200 Illumination device 300 Portable telephone

Claims (20)

A light source, a first light guide plate that receives light emitted from the light source and emits a part thereof in a first direction, and a second part that emits another part in a second direction different from the first direction. An illumination device comprising two light guide plates,
The first light guide plate emits a first incident end face that receives light emitted from the light source, and a part of the light incident on the first incident end face that intersects the first incident end face in the first direction. A first exit main surface, a first facing surface facing the first exit main surface, the first entrance end surface facing the first entrance end surface via the first exit main surface and the first facing surface; And an emission end face that emits another part of the light incident from
The second light guide plate is disposed to face the first facing surface of the first light guide plate and the first portion disposed to face the emission end surface of the first light guide plate. A first portion and a second portion that is continuous;
The first portion includes a second incident end surface that receives light emitted from the emission end surface of the first light guide plate, and a conversion surface that changes a traveling direction of light incident from the second incident end surface, Introducing at least a part of the light emitted from the emission end face into the second part while changing the traveling direction;
The second part is disposed on the opposite side to the side facing the first facing surface, and is a second emission main that emits at least a part of the light introduced by the first part in the second direction. And a second opposing surface that is disposed on a side facing the first opposing surface and that opposes the second emission main surface,
Furthermore, the first light guide plate has a shape that becomes substantially thinner from the first incident end face toward the outgoing end face, and the second portion of the second light guide plate includes the first light guide plate. A lighting device having a shape in which the thickness is substantially reduced as the distance from the portion increases.   The lighting device according to claim 1, further comprising a first reflecting member provided between the first facing surface and the second facing surface.   The lighting device according to claim 1, further comprising a second reflecting member provided so as to cover the conversion surface of the first portion.   The lighting device according to claim 1, further comprising a chassis that holds the first light guide plate and the second light guide plate, wherein the chassis is made of a reflective material. A light source, a first light guide unit that receives light emitted from the light source and emits a part thereof in a first direction, and another part is emitted in a second direction different from the first direction. A second light guide,
The first light guide section emits a first incident end face that receives light emitted from the light source and a part of the light that intersects the first incident end face and is incident from the first incident end face in the first direction. A first exit main surface, a first facing surface facing the first exit main surface, the first entrance end surface facing the first entrance end surface via the first exit main surface and the first facing surface. An emission end face that emits another part of the light incident from the end face;
The second light guide portion is disposed so as to face the first facing surface of the first light guide plate, and is disposed on a side opposite to the side facing the first facing surface. A second emission main surface that emits at least part of the light introduced into the portion in the second direction, and a second opposite surface that is disposed on the side facing the first opposite surface and faces the second emission main surface A lighting device having a surface,
A third light guide portion disposed so as to face the emission end face of the first light guide portion;
The third light guide unit includes a second incident end surface that receives light emitted from the emission end surface of the first light guide plate, and a conversion surface that changes a traveling direction of light incident from the second incident end surface. Introducing at least a part of the light emitted from the exit end face into the second light guide part by changing the traveling direction;
The lighting device, wherein the second light guide unit and the third light guide unit are integrally formed so as to be continuous with each other.   The lighting device according to claim 5, further comprising a first reflecting member provided between the first facing surface and the second facing surface.   The lighting device according to claim 5, further comprising a second reflecting member provided so as to cover at least the conversion surface of the third light guide unit.   The illumination according to claim 5, further comprising a chassis that holds the first light guide unit, the second light guide unit, and the third light guide unit, wherein the chassis is formed of a reflective material. apparatus.   The lighting device according to claim 1, wherein the conversion surface has a plurality of surfaces that are not parallel to each other.   The plurality of surfaces of the conversion surface include a first surface that forms an angle of approximately 45 ° with respect to the second incident end surface, and a second surface that forms an angle of approximately 90 ° with respect to the first surface. The lighting device according to claim 9, comprising:   The lighting device according to claim 9, wherein the plurality of surfaces of the conversion surface are three or more surfaces including a surface that forms an angle of less than 45 ° with the second incident end surface. A light source, a first light guide plate that receives light emitted from the light source and emits a part thereof in a first direction, and a second part that emits another part in a second direction different from the first direction. An illumination device comprising two light guide plates,
The first light guide plate includes a first part disposed on the light source side, and a second part disposed on a side opposite to the light source with respect to the first part and continuous with the first part. Including
The first portion includes a first incident end face that receives light emitted from the light source, an emission end face that is opposed to a part of the first incident end face, and emits a part of the light incident from the first incident end face. Have
The second portion includes a first emission main surface that emits another part of the light incident from the first incident end surface of the first portion in the first direction, and a first emission main surface. An opposing first opposing surface,
The second light guide plate is disposed so as to face the first facing surface of the second portion, and receives a light incident from the light emitting end surface of the first portion, A second emission main surface arranged on the opposite side to the side facing the first opposed surface and emitting at least part of the light incident from the second incident end surface in the second direction; and the first opposed surface And a second facing surface that is disposed on the facing side and faces the second emission main surface.   The lighting device according to claim 12, further comprising a reflecting member provided between the first facing surface and the second facing surface.   The lighting device according to claim 12, further comprising a chassis that holds the first light guide plate and the second light guide plate, wherein the chassis is formed of a reflective material.   The lighting device according to claim 1, wherein the light source is at least one light emitting diode.   The lighting device according to claim 1, wherein the amount of light emitted in the second direction is 1/20 or more of the amount of light emitted in the first direction.   17. The lighting device according to claim 1, a first display panel that modulates light emitted from the lighting device in the first direction, and the first display panel with respect to the lighting device. And a second display panel arranged on the opposite side and configured to modulate light emitted from the illumination device in the second direction.   17. The lighting device according to claim 1, a first display panel that modulates light emitted from the lighting device in the first direction, and the first display panel with respect to the lighting device. A second display panel that is arranged on the opposite side and modulates light emitted from the lighting device in the second direction; a housing that houses the lighting device, the first display panel, and the second display panel; Portable electronic device with   The housing includes a display unit that houses the lighting device, the first display panel, and the second display panel, an operation unit that includes at least an operation key, and a connection that connects the display unit and the operation unit. The portable electronic device according to claim 18, wherein the portable electronic device can be folded at the connecting portion.   The first display panel and the second display panel are liquid crystal display panels that perform display in a normally white mode, and when one of the first display panel and the second display panel displays information, the other is The portable electronic device according to claim 18 or 19, wherein a signal for performing black display is supplied.

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