CA1289534C - Planar light emitting device - Google Patents
Planar light emitting deviceInfo
- Publication number
- CA1289534C CA1289534C CA000531514A CA531514A CA1289534C CA 1289534 C CA1289534 C CA 1289534C CA 000531514 A CA000531514 A CA 000531514A CA 531514 A CA531514 A CA 531514A CA 1289534 C CA1289534 C CA 1289534C
- Authority
- CA
- Canada
- Prior art keywords
- light emitting
- light
- emitting device
- light sources
- planar light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/1336—Illuminating devices
- G02F1/133615—Edge-illuminating devices, i.e. illuminating from the side
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/02—Constructional features of telephone sets
- H04M1/0202—Portable telephone sets, e.g. cordless phones, mobile phones or bar type handsets
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/02—Constructional features of telephone sets
- H04M1/22—Illumination; Arrangements for improving the visibility of characters on dials
Landscapes
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Planar Illumination Modules (AREA)
- Liquid Crystal (AREA)
- Light Guides In General And Applications Therefor (AREA)
Abstract
ABSTRACT
A planar light emitting device for use with, for example, a liquid crystal displaypanel, comprising a body which is formed of a transparent synthetic resin, a light emitting panel which has one surface thereof worked into a prism in correspondence with the liquid crystal display-panel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to the light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from the light sources.
A planar light emitting device for use with, for example, a liquid crystal displaypanel, comprising a body which is formed of a transparent synthetic resin, a light emitting panel which has one surface thereof worked into a prism in correspondence with the liquid crystal display-panel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to the light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from the light sources.
Description
~i~89534 The present invention relates to planar light emitting devices for use in, for example, the back lights of liquid crystal displaypanels (LCDs) which are installed in portable telephones etc. More particularly, it relates to a S planar light emitting device which is thin.
In the prior art there is found a planar light emitting device which is provided with a diffusive sheet having a light emitting surface at its front and with a predetermined printed circuit board at its rear. Inside the planar light emitting device which is comparatively thin, there are formed a diffusion layer made from a diffusant, which diffuses the light of a plurality of light sources such as light emitting diodes (LEDs) disposed in the vicinities of the printed circuit board, and slanting surfaces or a slanting surface which efficiently guide(s) the light of the light sources to the light emitting surface of the thin planar light emitting device. The rectilinear slanting surfaces flare toward the front while defining an angle of about 90 therebetween, and the slanting surface is made substantially parabolic. There are also provided a plurality of shield walls which are near the respective light sources so as to prevent the light of these light sources from rectilinearly propagating directly toward the light emitting surface. Circular or semicurcular fringe patterns of the respective light sources are directly seen from outside the device through the diffusion layer as well as the light emitting surface because the light emitted from the light sources is not sufficiently diffused by the diffusion layer.
The prior-art planar light emitting device described above may be assembled in a portable telephone. A
casing in which a plurality of key buttons are arrayed has the planar light emitting device placed on one side thereof.
The planar light emitting device is attached to the casing ~ O . .
~ ..
by a holder together with a microconnector and a liquid crystal displaypanel. There is also provided a cover.
The prior-art planar light emitting device is constructed as described above. Therefore, the light emitted from the light source is diffused by the diffusion layer made from the diffusant packed inside the device and is diffused again by the diffusive sheet while being reflected in predetermined directions by the slanting surfaces or the slanting surface, whereupon it is given forth to the exterior from the light emitting surface.
Since, however, the planar light emitting device of the specified type is thin, the distance from the light sources to the light emitting surface is very short, and the light of the light sources is not sufficiently diffused within the diffusion layer. This incurs the disadvantage that the circular or semicircular fringe patterns are on the light emitting surface, and uniform planar light emission is not attained. In addition, even when the shield walls are respectively disposed near the light sources so as to prevent the light of the light sources from rectilinearly propagating directly toward the light emitting surface, part of the light emergent from each light source turns round the edge of the corresponding shield wall and rectilinearly propagates toward the light emitting surface because the area of the shield wall is small. This incurs the disadvantage that the semicircular fringe patterns of the respective light sources are similarly directly seen from outside the device through the diffusion layer as well as the light emitting surface, and the uniform planar light emission is not attained, either. Other disadvantages are that, since the light emitting diodes (LEDs) are inevitably employed in the thin planar light emitting device of the specified type, the printed circuit board for mounting the light sources of these light emitting diodes must be ~:A
~3953~
disposed at the rear of the planar light emitting device, and that the holder is required for mounting the planar light emitting device and the liquid crystal displaypanel on the casing.
The present invention has been made in view of such drawbacks, and has for its object to provide a planar light emitting device which is not limited by the size of a light source and with which the light of the light source is sufficiently diffused to attain uniform planar light emission even when the device is thin.
The pianar light emitting device according to this invention comprises a body which is formed of a transparent synthetic resin, a light emitting pan /
/
~, ~L2139534 has one surface thereof worked into a prism in corre-spondence with a liquid crystal displaypanel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to said light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from said light sources.
In this invention, the reflective sheets stuck on the light emitting panel of the body function to decide the traveling directions of light from the light sources not opposing to the light emitting panel, so that the light may travel toward the light guide plate; the light guide plate functions to prevent lowering in the luminous intensity of the light at positions distant from the light sources; and the prism-worked surface formed at one sur-face of the light emitting panel functions to efficiently guide the light of the light sources to the light emitting panel, whereby uniform planar light emission is attained.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 a and 1 b and Figs. 2 a and 2 b all illustrate an embodiment of this invention, in which Fig.
1 a is a front view showing a body with a cover, a liquid crystal displaypanel and a microconnector detached there-from, Fig. 1 a is an exploded vertical sectional view of the body, Fig. 2 a is a perspective view showing the front of the body, and Fig. 2 b is a perspective view showing the rear of the body.
Figs. 3 a and 3 b and Figs. 4 a and 4 b illust-rate other embodiments of this invention, respectively, in 12~39S34 A `~
which each of Fig. 3 a and Fig. 4 a is a front view showing a body with a cover, a liquid crystal displaypanel and a microconnector detached therefrom, and each of Fig.
3 b and Fig. 4 b is an exploded vertical sectional view of the body.
Figs. 5 a and 5 b , Figs. 6 a and 6 b and Fig. 7 illustrate prior-art planar light emitting devices of the specified type, in which Fig. 5 a and Fig. 6 a are front views, Fig. 5 b and Fig. 6 b are exploded vertical sectional views, and Fig. 7 is an exploded perspective view showing part of a casing for assembling the prior-art planar light emitting device therein.
PREFERRED EMBODIMENTS OF THE INVENTION
Figs. 1 a and 1 b and Figs. 2 a and 2 b illust-rate one embodiment of this invention. Referring to the figures, numeral 1 designates a body which is made of a transparent synthetic resin. Numeral 2 designates a light emitting panel which is formed with a prism-worked surface 2a being, for example, roughened at the front thereof in correspondence with a liquid crystal displaypanel 13 that is placed on the front at the stage of assemblage, and which has a reflective sheet 10b stuck on a slanting surface 7b that is formed at the rear of the panel. A
reflective sheet 10a is stuck on a slanting surface 7a which is formed on one side of the front of this light emitting panel 2. Also, the body 1 formed with the slanting surface 7b is formed with a light guide plate 12 which is thinned in a wedge shape as it becomes more distant from light sources 4 to be described later. Shown at numerals 11 are recesses which correspond to the plurality of light sources 4 such as light emitting diodes A -(L~Ds) disposed at the predetermined positions of a printed circuit board 5 that is placed and mounted on the rear surface of the body 1, and which receive the light sources 4 when the printed circuit board 5 is placed. An accommodating chamber 14 for receiving the liquid crystal displaypanel 13 is formed in the body 1 in correspondence with the light emitting panel 2, and a plurality of ribs 14a and 14b for positioning the liquid crystal display-panel 13 are formed at the peripheral wall of this accommodating chamber 14. A through hole 16 is provided on one side of the accommodating chamber 14, and receives a microconnector 15 for electrically connecting the llquid crystal displaypanel 13 and the printed circuit board 5.
A plurality of key buttons 17 are disposed in the body 1 so as to protrude out of a cover 18, a plurality of spacers 19 serve to fill up the gaps between the liquid crystal displaypanel 13 and the cover 18, and a plurality of reflectors 20 are disposed on the other side of the printed circuit board 5 in order to reflect the light of the light sources 4 toward the liquid crystal displaypanel 13.
The planar light emitting device of this invention is constructed as described above. Therefore, the light emergent from the light sources 4 is led toward the light guide plate 12 by the larger slanting surface 7b as well as the smaller slanting surface 7a formed in the part of the body 1 and the larger reflective sheet lOb as well as the smaller reflective sheet lOa stuck thereto, and it is efficiently diffused within the light guide plate 12 while repeating irregular reflections. The light of the light sources 4 is further diffused so as to become uniform planar light emission by means of the prism-worked surface 2a which is formed at the front of the light emitting s~
panel 2.
Figs. 3 a and 3 b and Figs. 4 a and 4 b illust-rate other embodiments of this invention, respectively.
Fig. 3 a or Fig. 4 a is a front view showing the body from which the cover, the liquid crystal displaypanel and the microconnector are detached, while Fig. 3 b or Fig.
4 b is an exploded vertical sectional view of the body.
The embodiment of Figs. 3 a and 3 b is such that the plurality of key buttons 17 explained in the foregoing embodiment are omitted, and that the light sources 4 are held within the recesses 11 provided in the body 1. On the other hand, the embodiment of Figs. 4 a and 4 b is such that the plurality of light sources 4 are held within the recesses 11 and 11 which are formed on both the sides of the accommodating chamber 14 for the liquid crystal displaypanel 13 as formed in the body 1, while the printed circuit board 5 in the foregoing embodiment is omitted, thereby to reduce the thickness of the planar light emitting device still more. The functional effects of the embodiments are quite the same as those of the foregoing embodiment.
As set forth above, the planar light emitting device according to tllis invention is constructed of a body which is formed of a transparent synthetic resin, a light emitting panel which has one surface thereof worked into a prism in correspondence with a liquid crystal displaypanel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to said light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from said light sources. Therefore, 1~8~534 the reflective sheets stuck on the light emitting panel of the body function to decide the travelling direction of light so that the light from the light sources not opposing to the light emitting panel may travel toward the light S guide plate, and the light guide plate functions to efficiently diffuse the light from the light sources while repeating irregular reflections, thereby to prevent lowering in the luminous intensity of the light at positions distant from the light sources, and the prism-worked surface is formed at one surface of the light emitting panel, thereby to guide the light of the light sources to the light emitting panel with the very thin structure and at high efficiency, to produce the excellent effect that uniform planar light emission is attained. Besides, this invention lS produces the effect that the light sources received in the recesses within the body formed of the transparent synthetic resin can serve also for illuminating key buttons mounted in the body.
Fig. 5a and Fig. 6a are front views showing prior-art planar light emitting devices of the specified type, while Fig. Sb and Fig. 6b are vertical sectional views of the respective devices. Numeral 1 designates the planar light emitting device which is provided with a diffusive sheet 6 having a light emitting surface 2 at its front and with a predetermined printed circuit board S at its rear.
Inside the planar light emitting device which is comparatively thin, there are formed a diffusion layer 3 made from a diffusant, which diffused the light of a plurality of light sources 4 such as light emitting diodes (LEDs) disposed in the vicinities of the printed circuit board 5, and slanting surfaces 7a or a slanting surface 7b which efficiently guide(s) the light of the light sources 4 to the light emitting surface 2 of the thin planar light emitting device 1. In the device shown in Fig. 5b, the rl A~
-~ 289~3~
rectilinear slanting surfaces 7a flare toward the front while defining an angle of about 90C therebetween, and in the device shown in Fig. 6b, the slanting surface 7b is made substantially parabolic. In the figures, numerals 8 indicate a plurality of shield walls which are provided near the respective light sources 4 so as to prevent the light of these light sources 4 from rectilinearly propagating directly toward the light emitting surface 2. Besides, numerals 9 indicate the circular or semicircular fringe patterns of the respective light sources 4 which are directly seen from outside the device through the diffusion layer 3 as well as the light emitting surface 2 because the light emitted from the light sources 4 is not sufficiently diffused by the diffusion layer 3.
Next, Fig. 7 is an exploded perspective view showing part of the casing of, for example, a portable telephone into which the prior-art planar light emitting device described above is assembled. Numeral 23 designates the casing in which a plurality of key buttons 17 are arrayed and which has the planar light emitting device 1 placed on one side thereof. The planar light emitting device l is attached to the casing 23 by a holder 22 together with a microconnector 15 and a liquid crystal displaypanel 13. Shown at numeral 18 is a cover.
The prior-art planar light emitting device is constructed as described above. Therefore, the light emitted from the light source 4 is diffused by the diffusion layer 3 made from the diffusant packed inside the device and is diffused again by the diffusive sheet 6 while being reflected in predetermined directions by the slanting surfaces 7a or the slanting surface 7b, whereupon it is given forth to the exterior from the light emitting surface 2. Since, however, the planar light emitting device 1 of the specified type is thin, the distance from the light ~,~
3953~
sources 4 to the light emitting surface 2 is very short, and the light of the light sources 4 is not sufficiently diffused within the diffusion layer 3. This incurs the disadvantage that, as shown in Fig. 5a or Fig. 6a, the circular or semicircular fringe patterns 9 are seen on the light emitting surface 2, and uniform planar light emission is not attained. In addition, even when as shown in Figs.
6a and 6b, the shield walls 8 are respectively disposed near the light sources 4 so as to prevent the light of the light sources 4 from rectilinearly propagating directly toward the light emitting surface 2, part of the light emergent from each light source 4 turns round the edge of the corresponding shield wall 8 and rectilinearly propagates toward the light emitting surface 2 because the area of the shield wall 8 is small. This incurs the disadvantage that, as shown in Fig. 6a, the semicircular fringe patterns 9 of the respective light sources 4 are similarly directly seen from outside the device through the diffusion layer 3 as well as the light emitting surface 2, and the uniform planar light emission is not attained, either. Other disadvantages are that, since the light emitting diodes (LEDs) are inevitably employed in the thin planar light emitting device of the specified type, the printed circuit board 5 for mounting the light sources 4 of these light emitting diodes must be disposed at the rear of the planar light emitting device 1, and that the holder 22 is required for mounting the planar light emitting device 1 and the liquid crystal displaypanel 13 on the casing 23.
In the prior art there is found a planar light emitting device which is provided with a diffusive sheet having a light emitting surface at its front and with a predetermined printed circuit board at its rear. Inside the planar light emitting device which is comparatively thin, there are formed a diffusion layer made from a diffusant, which diffuses the light of a plurality of light sources such as light emitting diodes (LEDs) disposed in the vicinities of the printed circuit board, and slanting surfaces or a slanting surface which efficiently guide(s) the light of the light sources to the light emitting surface of the thin planar light emitting device. The rectilinear slanting surfaces flare toward the front while defining an angle of about 90 therebetween, and the slanting surface is made substantially parabolic. There are also provided a plurality of shield walls which are near the respective light sources so as to prevent the light of these light sources from rectilinearly propagating directly toward the light emitting surface. Circular or semicurcular fringe patterns of the respective light sources are directly seen from outside the device through the diffusion layer as well as the light emitting surface because the light emitted from the light sources is not sufficiently diffused by the diffusion layer.
The prior-art planar light emitting device described above may be assembled in a portable telephone. A
casing in which a plurality of key buttons are arrayed has the planar light emitting device placed on one side thereof.
The planar light emitting device is attached to the casing ~ O . .
~ ..
by a holder together with a microconnector and a liquid crystal displaypanel. There is also provided a cover.
The prior-art planar light emitting device is constructed as described above. Therefore, the light emitted from the light source is diffused by the diffusion layer made from the diffusant packed inside the device and is diffused again by the diffusive sheet while being reflected in predetermined directions by the slanting surfaces or the slanting surface, whereupon it is given forth to the exterior from the light emitting surface.
Since, however, the planar light emitting device of the specified type is thin, the distance from the light sources to the light emitting surface is very short, and the light of the light sources is not sufficiently diffused within the diffusion layer. This incurs the disadvantage that the circular or semicircular fringe patterns are on the light emitting surface, and uniform planar light emission is not attained. In addition, even when the shield walls are respectively disposed near the light sources so as to prevent the light of the light sources from rectilinearly propagating directly toward the light emitting surface, part of the light emergent from each light source turns round the edge of the corresponding shield wall and rectilinearly propagates toward the light emitting surface because the area of the shield wall is small. This incurs the disadvantage that the semicircular fringe patterns of the respective light sources are similarly directly seen from outside the device through the diffusion layer as well as the light emitting surface, and the uniform planar light emission is not attained, either. Other disadvantages are that, since the light emitting diodes (LEDs) are inevitably employed in the thin planar light emitting device of the specified type, the printed circuit board for mounting the light sources of these light emitting diodes must be ~:A
~3953~
disposed at the rear of the planar light emitting device, and that the holder is required for mounting the planar light emitting device and the liquid crystal displaypanel on the casing.
The present invention has been made in view of such drawbacks, and has for its object to provide a planar light emitting device which is not limited by the size of a light source and with which the light of the light source is sufficiently diffused to attain uniform planar light emission even when the device is thin.
The pianar light emitting device according to this invention comprises a body which is formed of a transparent synthetic resin, a light emitting pan /
/
~, ~L2139534 has one surface thereof worked into a prism in corre-spondence with a liquid crystal displaypanel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to said light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from said light sources.
In this invention, the reflective sheets stuck on the light emitting panel of the body function to decide the traveling directions of light from the light sources not opposing to the light emitting panel, so that the light may travel toward the light guide plate; the light guide plate functions to prevent lowering in the luminous intensity of the light at positions distant from the light sources; and the prism-worked surface formed at one sur-face of the light emitting panel functions to efficiently guide the light of the light sources to the light emitting panel, whereby uniform planar light emission is attained.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 a and 1 b and Figs. 2 a and 2 b all illustrate an embodiment of this invention, in which Fig.
1 a is a front view showing a body with a cover, a liquid crystal displaypanel and a microconnector detached there-from, Fig. 1 a is an exploded vertical sectional view of the body, Fig. 2 a is a perspective view showing the front of the body, and Fig. 2 b is a perspective view showing the rear of the body.
Figs. 3 a and 3 b and Figs. 4 a and 4 b illust-rate other embodiments of this invention, respectively, in 12~39S34 A `~
which each of Fig. 3 a and Fig. 4 a is a front view showing a body with a cover, a liquid crystal displaypanel and a microconnector detached therefrom, and each of Fig.
3 b and Fig. 4 b is an exploded vertical sectional view of the body.
Figs. 5 a and 5 b , Figs. 6 a and 6 b and Fig. 7 illustrate prior-art planar light emitting devices of the specified type, in which Fig. 5 a and Fig. 6 a are front views, Fig. 5 b and Fig. 6 b are exploded vertical sectional views, and Fig. 7 is an exploded perspective view showing part of a casing for assembling the prior-art planar light emitting device therein.
PREFERRED EMBODIMENTS OF THE INVENTION
Figs. 1 a and 1 b and Figs. 2 a and 2 b illust-rate one embodiment of this invention. Referring to the figures, numeral 1 designates a body which is made of a transparent synthetic resin. Numeral 2 designates a light emitting panel which is formed with a prism-worked surface 2a being, for example, roughened at the front thereof in correspondence with a liquid crystal displaypanel 13 that is placed on the front at the stage of assemblage, and which has a reflective sheet 10b stuck on a slanting surface 7b that is formed at the rear of the panel. A
reflective sheet 10a is stuck on a slanting surface 7a which is formed on one side of the front of this light emitting panel 2. Also, the body 1 formed with the slanting surface 7b is formed with a light guide plate 12 which is thinned in a wedge shape as it becomes more distant from light sources 4 to be described later. Shown at numerals 11 are recesses which correspond to the plurality of light sources 4 such as light emitting diodes A -(L~Ds) disposed at the predetermined positions of a printed circuit board 5 that is placed and mounted on the rear surface of the body 1, and which receive the light sources 4 when the printed circuit board 5 is placed. An accommodating chamber 14 for receiving the liquid crystal displaypanel 13 is formed in the body 1 in correspondence with the light emitting panel 2, and a plurality of ribs 14a and 14b for positioning the liquid crystal display-panel 13 are formed at the peripheral wall of this accommodating chamber 14. A through hole 16 is provided on one side of the accommodating chamber 14, and receives a microconnector 15 for electrically connecting the llquid crystal displaypanel 13 and the printed circuit board 5.
A plurality of key buttons 17 are disposed in the body 1 so as to protrude out of a cover 18, a plurality of spacers 19 serve to fill up the gaps between the liquid crystal displaypanel 13 and the cover 18, and a plurality of reflectors 20 are disposed on the other side of the printed circuit board 5 in order to reflect the light of the light sources 4 toward the liquid crystal displaypanel 13.
The planar light emitting device of this invention is constructed as described above. Therefore, the light emergent from the light sources 4 is led toward the light guide plate 12 by the larger slanting surface 7b as well as the smaller slanting surface 7a formed in the part of the body 1 and the larger reflective sheet lOb as well as the smaller reflective sheet lOa stuck thereto, and it is efficiently diffused within the light guide plate 12 while repeating irregular reflections. The light of the light sources 4 is further diffused so as to become uniform planar light emission by means of the prism-worked surface 2a which is formed at the front of the light emitting s~
panel 2.
Figs. 3 a and 3 b and Figs. 4 a and 4 b illust-rate other embodiments of this invention, respectively.
Fig. 3 a or Fig. 4 a is a front view showing the body from which the cover, the liquid crystal displaypanel and the microconnector are detached, while Fig. 3 b or Fig.
4 b is an exploded vertical sectional view of the body.
The embodiment of Figs. 3 a and 3 b is such that the plurality of key buttons 17 explained in the foregoing embodiment are omitted, and that the light sources 4 are held within the recesses 11 provided in the body 1. On the other hand, the embodiment of Figs. 4 a and 4 b is such that the plurality of light sources 4 are held within the recesses 11 and 11 which are formed on both the sides of the accommodating chamber 14 for the liquid crystal displaypanel 13 as formed in the body 1, while the printed circuit board 5 in the foregoing embodiment is omitted, thereby to reduce the thickness of the planar light emitting device still more. The functional effects of the embodiments are quite the same as those of the foregoing embodiment.
As set forth above, the planar light emitting device according to tllis invention is constructed of a body which is formed of a transparent synthetic resin, a light emitting panel which has one surface thereof worked into a prism in correspondence with a liquid crystal displaypanel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to said light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from said light sources. Therefore, 1~8~534 the reflective sheets stuck on the light emitting panel of the body function to decide the travelling direction of light so that the light from the light sources not opposing to the light emitting panel may travel toward the light S guide plate, and the light guide plate functions to efficiently diffuse the light from the light sources while repeating irregular reflections, thereby to prevent lowering in the luminous intensity of the light at positions distant from the light sources, and the prism-worked surface is formed at one surface of the light emitting panel, thereby to guide the light of the light sources to the light emitting panel with the very thin structure and at high efficiency, to produce the excellent effect that uniform planar light emission is attained. Besides, this invention lS produces the effect that the light sources received in the recesses within the body formed of the transparent synthetic resin can serve also for illuminating key buttons mounted in the body.
Fig. 5a and Fig. 6a are front views showing prior-art planar light emitting devices of the specified type, while Fig. Sb and Fig. 6b are vertical sectional views of the respective devices. Numeral 1 designates the planar light emitting device which is provided with a diffusive sheet 6 having a light emitting surface 2 at its front and with a predetermined printed circuit board S at its rear.
Inside the planar light emitting device which is comparatively thin, there are formed a diffusion layer 3 made from a diffusant, which diffused the light of a plurality of light sources 4 such as light emitting diodes (LEDs) disposed in the vicinities of the printed circuit board 5, and slanting surfaces 7a or a slanting surface 7b which efficiently guide(s) the light of the light sources 4 to the light emitting surface 2 of the thin planar light emitting device 1. In the device shown in Fig. 5b, the rl A~
-~ 289~3~
rectilinear slanting surfaces 7a flare toward the front while defining an angle of about 90C therebetween, and in the device shown in Fig. 6b, the slanting surface 7b is made substantially parabolic. In the figures, numerals 8 indicate a plurality of shield walls which are provided near the respective light sources 4 so as to prevent the light of these light sources 4 from rectilinearly propagating directly toward the light emitting surface 2. Besides, numerals 9 indicate the circular or semicircular fringe patterns of the respective light sources 4 which are directly seen from outside the device through the diffusion layer 3 as well as the light emitting surface 2 because the light emitted from the light sources 4 is not sufficiently diffused by the diffusion layer 3.
Next, Fig. 7 is an exploded perspective view showing part of the casing of, for example, a portable telephone into which the prior-art planar light emitting device described above is assembled. Numeral 23 designates the casing in which a plurality of key buttons 17 are arrayed and which has the planar light emitting device 1 placed on one side thereof. The planar light emitting device l is attached to the casing 23 by a holder 22 together with a microconnector 15 and a liquid crystal displaypanel 13. Shown at numeral 18 is a cover.
The prior-art planar light emitting device is constructed as described above. Therefore, the light emitted from the light source 4 is diffused by the diffusion layer 3 made from the diffusant packed inside the device and is diffused again by the diffusive sheet 6 while being reflected in predetermined directions by the slanting surfaces 7a or the slanting surface 7b, whereupon it is given forth to the exterior from the light emitting surface 2. Since, however, the planar light emitting device 1 of the specified type is thin, the distance from the light ~,~
3953~
sources 4 to the light emitting surface 2 is very short, and the light of the light sources 4 is not sufficiently diffused within the diffusion layer 3. This incurs the disadvantage that, as shown in Fig. 5a or Fig. 6a, the circular or semicircular fringe patterns 9 are seen on the light emitting surface 2, and uniform planar light emission is not attained. In addition, even when as shown in Figs.
6a and 6b, the shield walls 8 are respectively disposed near the light sources 4 so as to prevent the light of the light sources 4 from rectilinearly propagating directly toward the light emitting surface 2, part of the light emergent from each light source 4 turns round the edge of the corresponding shield wall 8 and rectilinearly propagates toward the light emitting surface 2 because the area of the shield wall 8 is small. This incurs the disadvantage that, as shown in Fig. 6a, the semicircular fringe patterns 9 of the respective light sources 4 are similarly directly seen from outside the device through the diffusion layer 3 as well as the light emitting surface 2, and the uniform planar light emission is not attained, either. Other disadvantages are that, since the light emitting diodes (LEDs) are inevitably employed in the thin planar light emitting device of the specified type, the printed circuit board 5 for mounting the light sources 4 of these light emitting diodes must be disposed at the rear of the planar light emitting device 1, and that the holder 22 is required for mounting the planar light emitting device 1 and the liquid crystal displaypanel 13 on the casing 23.
Claims (5)
1. A planar light emitting device comprising a body which is formed of a transparent synthetic resin, a light emitting panel which has one surface thereof worked into a prism in correspondence with a liquid crystal displaypanel and which has reflective sheets respectively stuck on slanting surfaces formed on both surfaces thereof, a plurality of light sources which are disposed at positions not opposing to said light emitting panel, and a light guide plate which is thinned in a wedge shape as it becomes more distant from said light sources.
2. A planar light emitting device as defined in Claim 1, wherein the prism-worked surface is roughened.
3. A planar light emitting device as defined in Claim 1, wherein said light sources are light emitting diodes.
4. A planar light emitting device as defined in Claim 1, wherein said light sources are received or held in recesses which are formed in said body.
5. A planar light emitting device as defined in Claim 1, wherein the liquid crystal displaypanel to be placed on said light emitting panel of said body is received in an accommodating chamber which is formed in said body in correspondence with said light emitting panel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP61153356A JP2755941B2 (en) | 1986-06-30 | 1986-06-30 | Surface emitting device |
| JP61-153356 | 1986-06-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1289534C true CA1289534C (en) | 1991-09-24 |
Family
ID=15560672
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000531514A Expired - Fee Related CA1289534C (en) | 1986-06-30 | 1987-03-09 | Planar light emitting device |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP2755941B2 (en) |
| AU (1) | AU595588B2 (en) |
| CA (1) | CA1289534C (en) |
| GB (1) | GB2192084B (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0310889A3 (en) * | 1987-10-09 | 1991-07-03 | Andreas Peiker | Display device comprising a plurality of light sources |
| GB2222293B (en) * | 1988-08-24 | 1992-06-17 | Stc Plc | Backlight for radio pager lcd |
| DE3834492A1 (en) * | 1988-10-11 | 1990-04-12 | Langmatz Lic Gmbh | LIGHT INDICATOR |
| DE4125034A1 (en) * | 1991-07-29 | 1993-02-04 | Telefunken Electronic Gmbh | Illumination module for transmissive type LCD display - has plastic block providing optical transmission of daylight and artificial light to illuminate directly and indirectly |
| JPH0772815A (en) * | 1992-12-15 | 1995-03-17 | Koito Mfg Co Ltd | Liquid crystal display device |
| DE4339314C2 (en) * | 1993-11-18 | 2001-05-17 | Mannesmann Vdo Ag | Display unit, in particular combination instrument |
| GB2334807A (en) * | 1998-02-27 | 1999-09-01 | Nokia Mobile Phones Ltd | Display assembly |
| JP2002169149A (en) * | 2000-12-01 | 2002-06-14 | Mitsubishi Electric Corp | Reflection-type liquid crystal display |
| US7711400B2 (en) | 2000-12-29 | 2010-05-04 | Vertu Limited | Casing |
| US7006349B2 (en) | 2000-12-29 | 2006-02-28 | Vertu Limited | Casing |
| CN100512328C (en) | 2000-12-29 | 2009-07-08 | 弗图有限公司 | Casing |
| GB2374235B (en) | 2000-12-29 | 2004-09-22 | Nokia Mobile Phones Ltd | A casing |
| US6925313B2 (en) | 2001-02-07 | 2005-08-02 | Hyundai Curitel Inc. | Folder-type mobile communication terminal having double-sided LCD |
| US6950680B2 (en) * | 2001-09-17 | 2005-09-27 | Nokia Corporation | Electronic device |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3863246A (en) * | 1973-07-09 | 1975-01-28 | Collins Radio Co | Backlighted display apparatus for preventing direct viewing of light sources |
| DE2707081A1 (en) * | 1977-02-18 | 1978-08-24 | Ackeret Design Studios | OPTICAL NUMBER SEGMENT DISPLAY |
| JPS53104197A (en) * | 1977-02-23 | 1978-09-11 | Stanley Electric Co Ltd | Miniature illuminator |
| JPS58209777A (en) * | 1982-05-31 | 1983-12-06 | 日本精機株式会社 | Liquid crystal display |
| JPS59186882U (en) * | 1983-05-30 | 1984-12-11 | 株式会社小糸製作所 | indicator |
| US4616295A (en) * | 1984-07-03 | 1986-10-07 | Hewlett-Packard Company | Apparatus for mounting and illuminating liquid crystal displays |
| JPS6136911U (en) * | 1984-08-08 | 1986-03-07 | スタンレー電気株式会社 | lighting equipment |
| JPS61217084A (en) * | 1985-03-22 | 1986-09-26 | 三菱レイヨン・エンジニアリング株式会社 | Image display unit |
-
1986
- 1986-06-30 JP JP61153356A patent/JP2755941B2/en not_active Expired - Lifetime
-
1987
- 1987-03-05 AU AU69736/87A patent/AU595588B2/en not_active Ceased
- 1987-03-09 CA CA000531514A patent/CA1289534C/en not_active Expired - Fee Related
- 1987-03-11 GB GB8705784A patent/GB2192084B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2755941B2 (en) | 1998-05-25 |
| AU595588B2 (en) | 1990-04-05 |
| GB8705784D0 (en) | 1987-04-15 |
| GB2192084A (en) | 1987-12-31 |
| JPS638718A (en) | 1988-01-14 |
| GB2192084B (en) | 1990-12-12 |
| AU6973687A (en) | 1988-01-07 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |