JP3903839B2 - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform illumination with uniform illuminance by securing introduction efficiency of light while preventing the scale increase of the entire illuminator. <P>SOLUTION: The illuminator illuminates a liquid crystal panel 1 by introducing light emitted by a light emission element 4 from a light incident part 10 provided at a corner part of a light guide plate 2 and emitting the light from the light guide plate 2 and the light incident part 10 by guiding the introduced light into the inside of the light guide plate 2. The lower surface of the light incident part 10 is formed by a flat surface 11 corresponding to the liquid crystal display panel 1 and an inclined surface 12 which is not corresponding to the liquid crystal display panel 1. Consequently, the illuminance of a part corresponding to the flat surface 11 of the light incident part 10 to the liquid crystal display panel 1 is prevented from becoming remarkably higher by the flat surface of the light incident part 10 even without projecting the entire of the light incident part 10 to the outside of the liquid crystal display panel 1. In addition, the light from the light emission element 4 is efficiently introduced into the inside of the light guide plate 2 by the inclined surface 12 of the light incident part 10. Thus, the scale of the entire illuminator is not increased and the liquid crystal display panel 1 is illuminated with the uniform illuminance while securing the introduction efficiency of the light. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a planar light emitting type illumination device.
[0002]
[Prior art]
Conventionally, as shown in FIG. 15 and FIG. 16, the flat light-emitting type illumination device is formed at a substantially rectangular light guide plate 2 disposed on the lower side of the liquid crystal display panel 1 and at a corner portion of the light guide plate 2. A light-emitting element 4 disposed opposite to the distal end surface 3a of the substantially trapezoidal light incident part 3, and the light emitted from the light-emitting element 4 is introduced from the light incident part 3, and the introduced light is guided. While reflecting the light by the reflective layer 5 provided on the lower surface of the light plate 2 and sequentially repeating the reflection between the reflective layer 5 and the upper surface of the light guide plate 2, the introduced light travels inside the light guide plate 2. The light guide plate 2 is sequentially emitted from the upper surface to illuminate the lower surface side of the liquid crystal display panel 1.
[0003]
In such a lighting device, in order to sufficiently introduce the light from the light emitting element 4 into the light guide plate 2, the entire lower surface of the light incident part 3 formed at the corner of the light guide plate 2 is directed to the light emitting element 4 side. The light is emitted from the light emitting element 4 toward the inside of the light guide plate 2. In this case, the reflective layer 5 provided on the lower surface of the light guide plate 2 is provided to extend on the inclined surface 6 on the lower surface of the light incident portion 3. The light emitting element 4 is composed of a light emitting diode that emits light in the visible light region, and is disposed on the circuit board 7 disposed on the lower side of the light guide plate 2 in a state facing the front end surface 3a of the light incident portion 3. It is provided together with electronic components such as LSI8.
[0004]
In such an illuminating device, when the light emitting element 4 emits light, as shown in FIG. 17, the emitted light in the visible light region enters the light incident portion 3 of the light guide plate 2, and this incident light is incident on the inclined surface 6. A part of the reflected light is emitted as it is from the upper surface of the light guide plate 2, but the other light is repeatedly reflected between the upper surface of the light guide plate 2 and the reflective layer 5 in the light guide plate 2. , The proceeding light is sequentially emitted from the upper surface of the light guide plate 2 to illuminate the lower surface of the liquid crystal display panel 1. In this case, the reflective layer 5 gradually increases in reflection efficiency as it moves away from the light emitting element 4 except for the portion corresponding to the inclined surface 6 of the light incident portion 3 in order to illuminate the liquid crystal display panel 1 with substantially uniform illuminance. It is desirable that a surface treatment (for example, a surface treatment in which a non-reflective material is formed in a dot shape so that its density gradually decreases from the light emitting element 4 side) is preferably performed. Further, the surface treatment described above is not performed on the reflective layer 5 corresponding to the inclined surface 6 of the light incident portion 3 in order to sufficiently incorporate the light from the light emitting element 4 into the light guide plate 2. .
[0005]
[Problems to be solved by the invention]
However, in such an illuminating device, since the entire lower surface of the light incident portion 3 of the light guide plate 2 is formed on the inclined surface 6, the light from the light emitting element 4 can be sufficiently taken into the light incident portion 3. A part of the light taken into the light incident part 3 is reflected by the inclined surface 6 on the lower surface and emitted as it is from the upper surface of the light incident part 3, and the emitted light is large. Illuminates the portion of the liquid crystal display panel 1 corresponding to the light incident portion 3, so that the portion of the liquid crystal display panel 1 corresponding to the light incident portion 3 is illuminated brighter than the other portions as shown in FIG. Therefore, there is a problem that uneven illumination occurs in the liquid crystal display panel 1.
In order to solve such a problem, the entire light incident portion 3 of the light guide plate 2 is provided so as to protrude outward from the liquid crystal display panel 1, thereby preventing uneven illumination on the liquid crystal display panel 1. Although considered, in such a structure, there is a problem that the size of the light guide plate 2 including the light incident portion 3 is increased, the mounting area is increased, and the entire apparatus is increased in size.
[0006]
SUMMARY OF THE INVENTION An object of the present invention is to ensure that light is introduced efficiently and the display element can be illuminated with substantially uniform illuminance without increasing the overall size of the apparatus.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention includes the following components.
According to the first aspect of the present invention, a substantially trapezoidal light incident portion is provided at the corner of the flat light guide plate in plan view, and light emitted from the light emitting element is introduced from the front end surface of the light incident portion. In the illumination device for illuminating the display element disposed above the light guide plate by guiding the introduced light into the light guide plate and causing the light guide plate and the light incident portion to emit light,
The light incident portion is formed in a flat surface in which a lower surface of a portion corresponding to the lower surface of the display element is continuous with a lower surface of the light guide plate, and a lower surface of a portion not corresponding to the lower surface of the display element is a lower surface of the light guide plate Is formed on an inclined surface inclined obliquely downward toward the light emitting element from
A boundary portion between the flat surface and the inclined surface in the light incident portion is formed on a vertical surface exposed on a lower surface side of the light incident portion, and light from the light emitting element is formed on the vertical surface on the inclined surface side. A first reflecting portion that is reflected toward the outer surface, and on the outer surfaces located on both sides of the substantially trapezoidal light incident portion, the light incident on the light incident portion from the light emitting element and traveling toward the outer surface; The illumination device is characterized in that a second reflection portion is provided that reflects light reflected by the first reflection portion toward an inner side of the light guide plate.
[0008]
In the invention according to claim 2, the light emitting element emits light of a specific wavelength region in an ultraviolet region and an infrared region outside the visible light region, and on the lower surface of the light guide plate and the lower surface of the light incident portion, Except for the inclined surface of the light incident portion, a light emitting portion that emits light in a visible light region in response to light in the specific wavelength region from the light emitting element is provided in a dot shape. The illumination device according to claim 1.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, with reference to FIGS. 1-4, 1st Embodiment of the illuminating device of this invention is described. The same parts as those in the conventional example shown in FIGS. 15 to 18 will be described with the same reference numerals.
In this illuminating device, the lower surface of the substantially trapezoidal light incident portion 10 provided at the corner of the light guide plate 2 includes a flat surface 11 corresponding to the liquid crystal display panel 1 and an inclined surface 12 not corresponding to the liquid crystal display panel 1. The other structure is almost the same as the conventional example.
[0016]
That is, as shown in FIGS. 3 and 4, the light incident portion 10 is formed on the flat surface 11 where the lower surface of the portion corresponding to the liquid crystal display panel 1 is continuous with the lower surface of the light guide plate 2, and corresponds to the liquid crystal display panel 1. The lower surface of the portion not to be formed is formed on the inclined surface 12 inclined obliquely downward toward the light emitting element 4. As shown in FIGS. 2 and 4, the boundary between the flat surface 11 and the inclined surface 12 in the light incident portion 10 is formed on the vertical surface 13, and the vertical surface 13 is the back surface of the light incident portion 10. It is exposed as it is on the side. Further, the reflective layer 5 provided on the lower surface of the light guide plate 2 is provided continuously on the lower surface of the flat surface 11 of the light incident portion 10 corresponding to the liquid crystal display panel 1, and does not correspond to the liquid crystal display panel 1. Although not provided on the inclined surface 12, the reflective layer 5 may be provided also on the inclined surface 12. In addition, the light emitting element 4 is comprised with the light emitting diode which light-emits the light of visible light region similarly to a prior art example.
[0017]
In such an illuminating device, when the light emitting element 4 is caused to emit light, as shown in FIG. 2, the emitted light in the visible light region enters the inside from the front end surface 10 a of the light incident portion 10. A small amount of light passes through the vertical surface 13 of the light incident part 10 and is emitted to the lower side of the flat surface 11, but most of the other light is the inclined surface 12 of the light incident part 10 and the light incident part 10. The light is reflected by the upper surface and the flat surface 11 of the light incident portion 10 and introduced into the light guide plate 2. That is, among the light incident on the light incident part 10, the light irradiated on the inclined surface 12 is reflected by the inclined surface 12 because the incident angle of most of the light is greater than or equal to the critical angle. Similarly, the light irradiated on the upper surface of the light incident part 10 is also reflected on the upper surface of the light incident part 10 because the incident angle of most of the light is not less than the critical angle. The light introduced into the light guide plate 2 in this manner is repeatedly reflected between the upper surface of the light guide plate 2 and the reflection layer 5, and then is sequentially emitted from the upper surface of the light guide plate 2 while traveling through the light guide plate 2. Thus, the lower surface of the liquid crystal display panel 1 is illuminated.
[0018]
Thus, according to this illumination device, since the portion corresponding to the liquid crystal display panel 1 in the lower surface of the light incident portion 10 is formed on the flat surface 11, the entire light incident portion 10 is displayed on the liquid crystal display as in the conventional example. Even if it is not provided so as to protrude outward from the panel 1, the amount of light emitted from the upper surface of the light incident portion 10 can be significantly reduced by the flat surface 11 of the light incident portion 10, as shown in FIG. Therefore, it is possible to prevent the illuminance of the liquid crystal display panel 1 at a portion corresponding to the light incident portion 10 from being significantly increased. In addition, since the portion of the lower surface of the light incident portion 10 that does not correspond to the liquid crystal display panel 1 is formed on the inclined surface 12, the light from the light emitting element 4 is reflected by the inclined surface 12 and efficiently introduced into the light guide plate 2. can do. Thereby, the introduction efficiency of light from the light emitting element 4 can be ensured and the liquid crystal display panel 1 can be illuminated with substantially uniform illuminance without increasing the size of the entire apparatus.
[0019]
[Second Embodiment]
Next, with reference to FIGS. 5-8, 2nd Embodiment of the illuminating device of this invention is described. In this case, the same parts as those in the first embodiment shown in FIGS.
This lighting device has a structure in which a first reflecting portion 15 is provided at a boundary portion between the flat surface 11 and the inclined surface 12 in the light incident portion 10 and a second reflecting portion 16 is provided on the outer surface of the light incident portion 10. ing. That is, the first reflecting portion 15 is provided on the vertical surface 13 formed at the boundary between the flat surface 11 and the inclined surface 12 in the light incident portion 10, and directs the light from the light emitting element 4 toward the inclined surface 12 side. It is configured to reflect. The second reflecting portion 16 is provided on the outer surface of the light incident portion 10, is incident on the light incident portion 10 from the light emitting element 4, and is reflected by the first reflecting portion 15 and toward the outer surface of the light incident portion 10. The light is reflected toward the inner side of the light guide plate 2. Except for these, the structure is the same as that of the first embodiment.
[0020]
Such an illuminating device has the same effects as those of the first embodiment, and in particular, as shown in FIG. 5, the first light provided at the boundary between the flat surface 11 and the inclined surface 12 in the light incident portion 10. The light from the light emitting element 4 is reflected toward the inclined surface 12 side of the light incident part 10 by the reflecting part 15, and from the light emitting element 4 by the second reflecting part 16 provided on the outer surface of the light incident part 10. The light incident on the light incident portion 10 and directed toward the outer surface of the light incident portion 10 and the light reflected by the first reflecting portion 15 are reflected toward the inner side of the light guide plate 2. 10 can be introduced into the light guide plate 2 with almost no loss. For this reason, the light introduction efficiency can be increased as compared with that of the first embodiment, and the liquid crystal display panel 1 can be illuminated more brightly.
[0021]
[Third Embodiment]
Next, with reference to FIGS. 9-11, 3rd Embodiment of the illuminating device of this invention is described. In this case, the same parts as those in the second embodiment shown in FIGS.
This illumination device uses an ultraviolet light emitting element 20 that emits light in the ultraviolet region as a light emitting element, and emits ultraviolet light except for the inclined surface 12 of the light incident part 10 on the lower surface of the light guide plate 2 and the lower surface of the light incident part 10. It has a structure in which light emitting portions 21 that emit light in the visible light region in response to light in the ultraviolet region from the element 20 are provided in a dot shape.
That is, the ultraviolet light emitting element 20 is configured by an ultraviolet light emitting diode (ultraviolet LED) that emits light in the ultraviolet region of a wavelength of 365 nm (nanometer: nanometer is one billionth of a meter) or 254 to 365 nm. ing.
[0022]
In addition, the light emitting unit 21 reacts to light in the ultraviolet region having a wavelength of 350 to 420 nm or 254 to 365 nm, emits colorless or colored light with light in the visible light region, and is transparent when not irradiated with light in the ultraviolet region. It is provided in the form of dots from the lower surface of the light guide plate 2 to the flat surface 11 of the light incident portion 10 by printing or coating. In this case, the light emitting unit 21 is provided so that the installation density near the ultraviolet light emitting element 20 is low and the installation density gradually increases as the distance from the ultraviolet light emitting element 20 increases. That is, the flat surface 11 of the light incident portion 10 is formed with the lowest installation density of the light emitting portions 21. Note that the reflective layer 5 in this case has a structure that is not subjected to surface treatment with a non-reflective material or the like so that the reflectance is substantially constant over the entire region.
[0023]
In such an illuminating device, as in the second embodiment, light in the ultraviolet region from the ultraviolet light emitting element 20 is almost lost by the inclined surface 12, the first reflecting portion 15, and the second reflecting portion 16 of the light incident portion 10. In particular, since the light emitted from the ultraviolet light emitting element 20 is light in the ultraviolet region and is invisible to human eyes, the lighting effect on the liquid crystal display panel 1 is However, when the light emitting unit 21 is irradiated with light in the ultraviolet region, the light emitting unit 21 reacts with the irradiated light to emit light in the visible light region visible to human eyes. The liquid crystal display panel 1 can be illuminated with light in the visible light region emitted by the light source 21.
[0024]
At this time, since the light emitting portion 21 is not provided on the inclined surface 12 of the light incident portion 10, the light in the ultraviolet region from the ultraviolet light emitting element 20 can be efficiently introduced into the light guide plate 2. Further, since the light emitting unit 21 is provided in a dot shape from the lower surface of the light guide plate 2 to the flat surface 11 of the light incident unit 10, the reflective layer exposed from the gap of the light emitting unit 21 provided in the dot shape. 5, the light in the ultraviolet region can be reflected and sequentially propagated to the inside of the light guide plate 2, and the light in the ultraviolet region can be sequentially irradiated to the light emitting portions 21 provided in a dot shape. Further, since the light emitting unit 21 is provided in a dot shape in which the installation density gradually increases as the distance from the ultraviolet light emitting element 20 increases, even if the light amount in the ultraviolet region decreases as the distance from the ultraviolet light emitting element 20 decreases, the light emitting unit 21 A decrease in the amount of light emission can be prevented, and the entire lower surface of the liquid crystal display panel 1 can be illuminated with substantially uniform illuminance.
[0025]
[Fourth Embodiment]
Next, with reference to FIGS. 12-14, 4th Embodiment of the illuminating device of this invention is described. In this case, the same parts as those in the third embodiment shown in FIGS.
This illumination device is different from the third embodiment in the structure of the light incident portion 30 of the light guide plate 2 and the reflective layer 5 positioned in the light incident portion 30, and other than this, the illumination device has almost the same structure as the third embodiment. . That is, the light incident portion 30 is formed in a substantially trapezoidal shape at the corner portion of the light guide plate 2 as in the conventional example, and the entire lower surface is formed on the inclined surface 31 inclined obliquely downward toward the ultraviolet light emitting element 20. Yes.
[0026]
In addition, the reflective layer 5 provided on the lower surface of the light guide plate 2 extends continuously from the inclined surface 31 of the light incident portion 30. Further, as shown in FIG. 12, the lower surface of the light guide plate 2 and the inclined surface 31 of the light entrance 10 emit light in the visible light region in response to light in the ultraviolet region from the ultraviolet light emitting element 20. The portion 21 is provided in a dot shape. Also in this case, the light emitting section 21 is provided so that the installation density gradually increases as the distance from the ultraviolet light emitting element 20 increases. That is, the light emitting part 21 of the inclined surface 31 of the light incident part 30 is provided in a dot shape having the lowest installation density.
[0027]
In such an illuminating device, when the ultraviolet light emitting element 20 emits light, as shown in FIG. 12, light in the ultraviolet region enters the inside from the front end surface 30 a of the light incident portion 30, and the incident light is inclined surface 31. The reflected light travels in the light guide plate 2 while being repeatedly reflected between the upper surface of the light guide plate 2 and the reflective layer 5, but the light in the ultraviolet region emitted by the ultraviolet light emitting element 20 Similar to the third embodiment, since the light is invisible to human eyes, there is no illumination effect on the liquid crystal display panel 1. However, when light in the ultraviolet region is irradiated onto the light emitting unit 21, the light emitting unit 21 reacts with the irradiated light and emits light in the visible light region visible to human eyes, as in the third embodiment. The liquid crystal display panel 1 can be illuminated with light in the visible light region emitted by the light emitting unit 21.
[0028]
At this time, since the installation density of the light emitting units 21 is the lowest on the inclined surface 31 of the light incident unit 30, a part of the light in the ultraviolet region from the ultraviolet light emitting element 20 is irradiated to the light emitting unit 21 to emit light in the visible light region. Light is emitted, but most of the other ultraviolet light is reflected by the inclined surface 31 and introduced into the light guide plate 2. For this reason, although the light incident part 30 has a large amount of light in the ultraviolet region, the amount of light emitted by the light emitting part 21 is small, so that the amount of light in the visible light region irradiated to the liquid crystal display panel 1 corresponding to this part is small. It is possible to prevent the illuminance of the liquid crystal display panel 1 corresponding to 30 from becoming extremely high. In addition, since the installation density of the light emitting unit 21 gradually increases as the distance from the ultraviolet light emitting element 20 increases, the amount of light emitted by the light emitting unit 21 does not increase even when the irradiation amount of light in the ultraviolet region gradually decreases as the distance from the ultraviolet light emitting element 20 increases. There is almost no decrease. For this reason, unlike the conventional example, it is not necessary to provide the entire light incident portion 30 so as to protrude outward from the liquid crystal display panel 1, so that the efficiency of introducing light from the light emitting element 4 can be improved without increasing the size of the entire device. The entire lower surface of the liquid crystal display panel 1 can be illuminated with substantially uniform illuminance.
[0029]
In the third and fourth embodiments, the ultraviolet light emitting element 20 that emits light in the ultraviolet region is used as the light emitting element, and light in the visible light region is emitted in response to the light in the ultraviolet region as the light emitting unit. Although the case where the light emitting unit 21 is used has been described, the present invention is not limited thereto. For example, an infrared light emitting element that emits light in an infrared region having a wavelength of 780 nm or more is used as the light emitting element, and an infrared ray having a wavelength of 780 nm or more is used as the light emitting unit. A structure using a light emitting portion that emits light in the visible light region in response to light in the region may be used. Even in such a structure, since the light in the infrared region is not visible to the human eye, the same effects as the third and fourth embodiments described above are obtained.
[0030]
【The invention's effect】
As described above , according to the present invention, the amount of light emitted from the upper surface of the light incident portion can be significantly reduced by the flat surface of the light incident portion, so that the illuminance of the display element in the portion corresponding to the light incident portion Can be prevented from becoming extremely high, and the light from the light emitting element can be efficiently introduced into the light guide plate by the inclined surface of the light incident portion, so that the entire apparatus is not increased in size and emits light. The display element can be illuminated with substantially uniform illuminance while ensuring the light introduction efficiency from the element. In this case, the first reflection part reflects light from the light emitting element toward the inclined part side of the reflection layer, and the second reflection part makes light incident on the light incident part from the light emitting element to the outer surface and the first reflection. The light reflected by the light can be reflected toward the inside of the light guide plate, so that the light incident on the light incident part from the light emitting element can be introduced into the light guide plate with almost no loss, For this reason, the light introduction efficiency can be increased, and the display element can be further illuminated brightly.
[Brief description of the drawings]
FIG. 1 is a plan view showing a first embodiment of a lighting device according to the present invention.
2 is a cross-sectional view illustrating an optical path state of light emitted from a light emitting element as viewed in the direction of arrows AA in FIG. 1;
FIG. 3 is an enlarged plan view of a light incident portion in FIG.
4 is an enlarged cross-sectional view of a light incident portion in FIG.
FIG. 5 is a plan view showing a second embodiment of the illumination device of the present invention.
6 is a cross-sectional view illustrating an optical path state of light emitted from the light emitting element when viewed along arrows BB in FIG. 5;
7 is an enlarged plan view of a light incident part in FIG. 5;
8 is an enlarged cross-sectional view of a light incident portion in FIG.
FIG. 9 is a cross-sectional view showing an optical path and a light emission state in a third embodiment of the illumination device of the present invention.
10 is an enlarged plan view of a light incident portion in FIG. 9;
11 is an enlarged cross-sectional view of a light incident portion in FIG. 9;
FIG. 12 is a cross-sectional view showing an optical path and a light emission state in a fourth embodiment of the illumination device of the present invention.
13 is an enlarged plan view of a light incident portion in FIG.
14 is an enlarged cross-sectional view of a light incident portion in FIG.
FIG. 15 is a plan view showing a conventional lighting device.
16 is a cross-sectional view taken along the line CC in FIG.
17 is a cross-sectional view illustrating an optical path state of light emitted from the light-emitting element of FIG. 16;
18 is a plan view illustrating a state in which the light-emitting element of FIG. 15 emits light.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Light-guide plate 4 Light emitting element 5 Reflective layer 10 and 30 Light entrance part 11 Flat surface 12, 31 Inclined surface 15 1st reflection part 16 2nd reflection part 20 Ultraviolet light emitting element 21 Light emission part

Claims (2)

A substantially trapezoidal light incident portion is provided at the corner of the flat light guide plate when viewed in plan, light emitted from the light emitting element is introduced from the front end surface of the light incident portion , and the introduced light is introduced into the light guide plate. In the illumination device that illuminates the display element disposed above the light guide plate by causing the light guide plate and the light incident portion to emit light by being guided to the inside of the light guide plate,
Before filling the optical part, the lower surface of the lower surface of the portion corresponding to the lower surface of the display element is formed on a flat surface continuous to the lower surface of the light guide plate, and the lower surface is the light guide plate of a portion not corresponding to the lower surface of the display device formed on the inclined surface inclined obliquely downward toward the light emitting element from,
A boundary portion between the flat surface and the inclined surface in the light incident portion is formed on a vertical surface exposed on a lower surface side of the light incident portion, and light from the light emitting element is formed on the vertical surface on the inclined surface side. A first reflecting portion that is reflected toward the outer surface, and on the outer surfaces located on both sides of the substantially trapezoidal light incident portion, the light incident on the light incident portion from the light emitting element and traveling toward the outer surface; 2. A lighting device, comprising: a second reflecting portion that reflects light reflected by the first reflecting portion toward an inner side of the light guide plate . The light emitting element emits light in a specific wavelength region out of an ultraviolet region and an infrared region that are outside the visible light region , and the inclined surface of the light incident unit is disposed on a lower surface of the light guide plate and a lower surface of the light incident unit. 2. The illumination according to claim 1 , wherein a light emitting unit that emits light in a visible light region in response to light in the specific wavelength region from the light emitting element is provided in a dot shape. apparatus.

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