U.S. patent application number 12/867134 was filed with the patent office on 2011-01-13 for light-emitting module and lighting apparatus.
This patent application is currently assigned to toshiba Lighting & Technology Corporation. Invention is credited to Hitoshi Kawano, Akiko Saito, Toshiya Tanaka.
Application Number | 20110006680 12/867134 |
Document ID | / |
Family ID | 40957034 |
Filed Date | 2011-01-13 |
United States Patent
Application |
20110006680 |
Kind Code |
A1 |
Tanaka; Toshiya ; et
al. |
January 13, 2011 |
LIGHT-EMITTING MODULE AND LIGHTING APPARATUS
Abstract
An object of the present invention is to provide a
light-emitting module having excellent light emission efficiency
and excellent light distribution characteristics and also provide a
lighting apparatus using the light-emitting module. The present
invention is a light-emitting module 1 including a substrate 2
having a front surface side 2a constituted as a component mounting
surface and a rear surface side 2b constituted as a flat heat
dissipating surface, a plurality of light-emitting elements 3 which
are arranged in a manner protruding at a central portion of the
component mounting surface of the substrate and which radiate light
at least in an upper surface direction and in a direction along the
component mounting surface, a lighting circuit component 4 which is
electrically connected to the light emitting elements 3 by a wiring
pattern arranged on the substrate 2 and which is arranged closer to
the peripheral edge side of the substrate than the light emitting
elements 3 on the component mounting surface of the substrate 2,
and a connector 5 for power supply connection, which is arranged
closer to the peripheral edge side of the substrate 2 than the
light emitting elements 3 on the component mounting surface of the
substrate 2 and which is electrically connected to the lighting
circuit component 4.
Inventors: |
Tanaka; Toshiya;
(Kanagawa-Ken, JP) ; Saito; Akiko; (Kanagawa-Ken,
JP) ; Kawano; Hitoshi; (Kanagawa-Ken, JP) |
Correspondence
Address: |
DLA PIPER LLP US
P. O. BOX 2758
RESTON
VA
20195
US
|
Assignee: |
toshiba Lighting & Technology
Corporation
Kabushiki Kaisha Toshiba
|
Family ID: |
40957034 |
Appl. No.: |
12/867134 |
Filed: |
February 13, 2009 |
PCT Filed: |
February 13, 2009 |
PCT NO: |
PCT/JP2009/052382 |
371 Date: |
September 23, 2010 |
Current U.S.
Class: |
315/35 |
Current CPC
Class: |
F21V 23/06 20130101;
H05K 1/181 20130101; F21K 9/20 20160801; F21V 29/70 20150115; F21K
9/232 20160801; F21V 29/76 20150115; F21Y 2115/10 20160801; F21K
9/00 20130101; F21Y 2105/10 20160801; F21S 8/02 20130101; F21V
29/89 20150115; F21V 23/005 20130101 |
Class at
Publication: |
315/35 |
International
Class: |
H01J 13/46 20060101
H01J013/46 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 14, 2008 |
JP |
2008-033673 |
Apr 30, 2008 |
JP |
2008-118292 |
Claims
1. A light-emitting module comprising: a substrate having a front
surface side constituted as a component mounting surface and a rear
surface side constituted as a heat dissipating surface flat in
shape; a plurality of light-emitting elements mounted at a central
portion of a component mounting surface of the substrate in a
manner protruding therefrom and emitting light at least in an upper
surface direction and in a direction along the component mounting
surface; a lighting circuit component which is electrically
connected to the light emitting elements by a wiring pattern
arranged on the substrate and which is arranged on a peripheral
edge side of the substrate than the light emitting elements, on the
component mounting surface of the substrate; and a connector for
connecting with a power supply, which is arranged on the peripheral
edge side of the substrate than the light emitting elements, on the
component mounting surface of the substrate, and which is
electrically connected to the lighting circuit component.
2. The light-emitting module according to claim 1, wherein the
plurality of light-emitting elements are arranged at even intervals
in rotational symmetry except at a central point of the central
portion of the component mounting surface of the substrate.
3. The light-emitting module according to claim 1, wherein when it
is determined that a minimum distance between light-emitting
portions of the plurality of the light-emitting elements arranged
is c, a width of the light-emitting portion on a line of the
minimum distance c is a, and a height from the mounting surface of
the substrate to an upper surface of the light-emitting portion is
b, the light-emitting elements are arranged so as to satisfy a
dimensional relationship of b<c<4a.
4. A lighting apparatus comprising: an apparatus body; and the
light-emitting module according to claim 1 incorporated in the
apparatus body.
Description
TECHNICAL FIELD
[0001] The present invention relates to a light-emitting module in
which a light-emitting element such as LED is arranged, and also
relates to a lighting apparatus provided with the light-emitting
module.
BACKGROUND ART
[0002] Conventionally, there has been provided a lighting equipment
including an LED module having a power feeding terminal and mounted
with an LED chip disposed thereon and an apparatus body provided
with a holding member for detachably holding the LED module (refer
to Patent Document 1). There is also provided a lighting equipment
also including a terminal for connecting a power feeding line
directly to the LED module so as to easily exchange the LED module
or to use the LED module in various equipments (refer to Patent
Document 2).
[0003] Patent Document 1: Japanese Patent Laid-Open Publication No.
2003-68129
[0004] Patent Document 2: Japanese Patent Laid-Open Publication No.
2003-59330
DISCLOSURE OF THE INVENTION
[0005] In the equipment disclosed in Patent Document 1, however,
though not specifically described, at least LED chips and circuit
components are disposed on a surface of the LED module in a mixed
manner. Therefore, the Patent Document 1 fails to disclose any
technical idea performing excellent distribution of light radiated
from the LED chip, and moreover, the rear surface of the LED module
is not positively used as a heat dissipating surface. Furthermore,
it is evident from the configuration of the power feeding terminal
and the holding member that the disclosed LED module has a specific
structure for attachment and connection, which requires a specified
adaptor, thus lacking versatility.
[0006] In the equipment disclosed in Patent Document 2, LED chips
and circuit components are similarly disposed on a surface of the
LED module in a mixed manner. Therefore, Patent Document 2 also
fails to disclose any specific technical idea performing excellent
distribution of light radiated from the LED chip.
[0007] The present invention has been made in view of the above
circumstances, and has an object to provide a light-emitting module
having excellent light emission efficiency and excellent light
distribution characteristics and also provide a lighting apparatus
using the light-emitting module.
[0008] A light-emitting module of the present invention includes: a
substrate having a front surface side constituted as a component
mounting surface and a rear surface side constituted as a heat
dissipating surface flat in shape; a plurality of light-emitting
elements mounted at a central portion of a component mounting
surface of the substrate in a manner protruding therefrom and
emitting light at least in an upper surface direction and in a
direction along the component mounting surface; a lighting circuit
component which is electrically connected to the light emitting
elements by a wiring pattern arranged on the substrate and which is
arranged on a peripheral edge side of the substrate than the light
emitting elements, on the component mounting surface of the
substrate; and a connector for connecting with a power supply,
which is arranged on the peripheral edge side of the substrate than
the light emitting elements, on the component mounting surface of
the substrate, and which is electrically connected to the lighting
circuit component.
[0009] According to the present invention, a light emitting module
having wide applicable range can be provided with excellent light
distribution characteristics and made optimized. Moreover, heat
dissipation effects can be promoted and the wiring pattern on the
substrate can be shortened and simplified, thus being
effective.
[0010] Furthermore, in the present invention of the above aspect,
it may be desired that the plurality of light-emitting elements are
arranged at even intervals in rotational symmetry except at a
central point of the central portion of the component mounting
surface of the substrate. According to this arrangement, since the
plurality of light emitting elements are arranged, it becomes
possible to perform heat radiation in a concentrated manner from a
portion near the center point of the substrate toward the rear
surface side thereof, thus realizing substantially even light
distribution characteristics in the horizontal direction.
[0011] Furthermore, in the present invention of the above aspect,
it may be desired that when it is supposed that a minimum distance
between light-emitting portions of the plurality of the
light-emitting elements arranged is c, a width of the
light-emitting portion on a line of the minimum distance c is a,
and a height from the mounting surface of the substrate to an upper
surface of the light-emitting portion is b, the light-emitting
elements are arranged so as to satisfy a dimensional relationship
of b<c<4a. According to this arrangement, the light-emitting
module having suppressed luminance irregularity is obtainable, thus
providing excellent light emission efficiency.
[0012] Still furthermore, in the present invention, the lighting
apparatus is desirable to be provided with an apparatus body, and
the light-emitting module according to any one of claims 1 to 3.
Here, the "lighting apparatus" may include a light source having a
cap, and lighting equipment used indoors or outdoors.
[0013] According to the above structure, the lighting apparatus
provided with the light-emitting module can achieve the effects
obtainable by the light-emitting module.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] [FIG. 1] is a plan view illustrating a first embodiment of a
light-emitting module according to the present invention.
[0015] [FIG. 2] is a partial side view, in an enlarged scale,
illustrating the light-emitting module according to the present
invention.
[0016] [FIG. 3] is a circuit diagram of the light-emitting module
according to the present invention.
[0017] [FIG. 4] is a schematic diagram illustrating a structure of
a first embodiment of a lighting apparatus according to the present
invention.
[0018] [FIG. 5] is a schematic diagram illustrating a structure of
a second embodiment of the lighting apparatus according to the
present invention.
[0019] [FIG. 6] is a schematic diagram illustrating a structure of
a third embodiment of the lighting apparatus of the present
invention.
[0020] [FIG. 7] is a plan view illustrating a modification of the
light-emitting module according to the first embodiment.
[0021] [FIG. 8] is a plan view (8(a) and a side view 8(b))
illustrating the light-emitting element (LED package) according to
the first embodiment of the light-emitting module.
[0022] [FIG. 9] is a graph showing a directional pattern of radiant
light of the light-emitting element.
[0023] [FIG. 10] is a plan view illustrating an arrangement of the
light-emitting elements.
[0024] [FIG. 11] is a schematic view showing illuminance
distribution on a floor surface when the light-emitting module is
lightened.
[0025] [FIG. 12] is a graph representing luminance irregularity and
light emitting efficiency relative to the interval between the
light-emitting elements.
[0026] [FIG. 13] is an explanatory view illustrating an example of
another application of the light-emitting element.
BEST MODE FOR CARRYING OUT THE INVENTION
[0027] A first embodiment of the present invention will be
described below with reference to FIGS. 1 to 3. FIG. 1 is a plan
view illustrating a light-emitting module, FIG. 2 is a partial
enlarged side view illustrating a light-emitting element, and FIG.
3 is a circuit diagram of the light-emitting module.
[0028] Referring to FIG. 1, a light-emitting module 1 includes a
disc-shaped substrate 2, light-emitting elements 3 mounted on the
substrate 2, a lighting circuit components 4, and a connector 5 for
power source connection.
[0029] The substrate 2 is made of aluminum, which is formed into a
disc plate shape, and having a thickness of about 1.5 mm and a
diameter of about 70 mm. In the substrate 2, a front surface side
2a is used as a component mounting surface, and a rear surface side
2b is used as a flat-shaped heat dissipating surface. On the
component mounting surface, eight light-emitting elements 3 are
mounted in a manner concentrated in the central portion of the
component mounting surface in a pattern spaced with a predetermined
interval from each other. When the substrate 2 is made of metal, it
is preferred to use a material such as aluminum or copper which is
excellent in heat conductivity and heat dissipation
characteristics. On the other hand, when an insulating material is
used for the substrate 2, a synthetic resin material or a ceramic
material containing thermal conduction filler, which has relatively
excellent heat dissipation characteristics and excellent
durability, may be utilized. In the case of using the synthetic
resin material, the substrate 2 may be formed of glass epoxy resin
or the like. Further, the shape of the substrate 2 is not limited
to circle and may be quadrangle or polygon.
[0030] The light-emitting elements 3 are a surface-mounted LED
package and are mainly constituted of a main body 3a formed of
ceramic, an LED chip mounted on the main body and a translucent
resin 3b for mold use, such as epoxy resin or silicon resin, which
seals the LED chip (refer to FIG. 2). A pair of lead terminals, not
shown, connected to the LED chip projects from the main body 3a in
a horizontal direction. In the LED package, four LED chips are
mounted, which are connected in series between electrodes of the
package, and accordingly, since eight LED packages each having four
LED chips are arranged, totally, thirty two (32) LED chips are
arranged. Needless to say, an LED package may also be used in which
a single LED chip is mounted.
[0031] The LED chip is a blue LED chip emitting blue light. The
translucent resin 3b for mold use contains a fluorescent material
which absorbs light emitted by the LED chip and generates yellow
light. The LED chip is molded on an upper surface of the main body
3a so as to form a flat plate with a predetermined thickness.
Accordingly, light from the LED chip is irradiated from an upper
surface and a side surface of the translucent resin 3b of the LED
package to the outside, and hence, the light from the LED chip has
a white-base luminescent color such as white color or electric bulb
color and has wide light distribution characteristics. That is,
light is irradiated from the light-emitting elements 3 in a
direction of the upper surface thereof and in a direction along the
component mounting surface. Further, the LED package is about 3.5
mm in breadth, 3.5 mm in width and 1.5 mm in height and has a shape
of a substantially rectangular solid.
[0032] An insulating layer is formed on a surface of the substrate
2, and on such insulating layer, a connection land connected to
lead terminals of the surface-mounted components and a wiring
pattern, not shown, are formed. In the central portion of the
substrate 2 except at a central point thereof, the light-emitting
elements 3 are arranged at a predetermined interval (3 mm to 15 mm,
preferably 5 mm to 10 mm) in rotational symmetry (in the present
embodiment, being 45.degree. symmetry relative to the light
emission center of the light-emitting elements 3) around the
central point along a direction of the front surface of the
substrate 2. Further, the lighting circuit components 4 are
arranged and mounted in an outer peripheral edge side of the
substrate 2, and in this case, the lighting circuit components 4
are never mounted between the light-emitting elements 3 and 3. The
lighting circuit components 4 are used for lighting control of the
LED chip, and include a fuse F, a capacitor C, a rectifier REC, a
constant voltage diode ZD, resistors R1 and R2, and a transistor Q.
A connector 5 for connecting with a power supply is similarly
arranged in a position around the light-emitting elements 3. The
connector 5 is arranged so that a connection opening 5a thereof
faces the outer peripheral edge of the substrate 2 and is disposed
close to the outer peripheral edge. This is for the purpose of
facilitating the connection with a power line of commercial power
supply. The lighting circuit components 4 and the connector 5 are
disposed closer to the outer peripheral edge side of the substrate
2 than the light-emitting elements 3, and arranged not in a
dispersed manner but in a relatively concentrated manner (in a
region disposed approximately 1/3 from the outer circumference of
the substrate 2) to shorten the wiring pattern of the substrate 2.
On the mounting surface of the substrate 2, a white resist having a
high reflectivity is printed, and three screw through-holes 6 are
formed on the mounting surface to be mounted onto an apparatus or
the like.
[0033] The light-emitting elements 3 protrude from the mounting
surface of the substrate 2 in a direction of height, and radiate,
as indicated by the arrow in FIG. 2, light in a radial pattern from
a protruding portion of the translucent resin 3b. Accordingly, not
only the light LV radiated in a direction perpendicular (upper
surface direction) to the mounting surface, but also the light LH
radiated from the side surface of the translucent resin 3b of the
LED package along the component mounting surface can be used.
[0034] Referring to the circuit diagram of FIG. 3, the capacitor C
is connected via the fuse F across a commercial power supply AC.
The full-wave rectifier REC is connected across the capacitor C,
and in the output terminal of the full-wave rectifier REC, a series
circuit of the resistor R1 and the constant voltage diode ZD, and a
series circuit of a plurality of the LED chips LED, the NPN
transistor Q and the resistor R2 are connected in parallel. A base
of the transistor Q is connected to a connecting point between the
resistor R1 and the constant voltage diode ZD. In the LED package,
four LED chips are, as described above, connected in series, and
hence, a series circuit of the transistor Q and the resistor R2 may
be constructed for each of the LED packages and then connected in
parallel with each other.
[0035] A constant current circuit is constituted by the circuit
mentioned above, and a current supplied from the commercial power
supply AC is converted to a DC current, and such DC current flows,
as constant current IF, in the series circuit of the LED chips LED,
the transistor Q and the resistor R2. More specifically, a base
voltage VB of the transistor Q is kept constant by the constant
voltage diode ZD so that current IC flowing into a collector of the
transistor Q is kept constant, and as a result, the current IF
flowing in the LED chip is made constant.
[0036] According to the present embodiment described above, the
light-emitting elements 3 are arranged in the central portion of
the component mounting surface of the substrate 2, and the lighting
circuit components 4 and the connector 5 for connecting with power
supply are arranged around the light-emitting elements 3.
Accordingly, the light LH radiated from the side surface of the
light-emitting elements 3, i.e., the LED packages, can be
effectively used, making excellent light distribution and also
optimizing light distribution. That is, when the light-emitting
elements 3, the lighting circuit components 4 and the connector 5
for connecting with power supply are arranged in a mixed manner,
particularly, the light LH radiated from the side surface of the
LED package is interrupted by the lighting circuit components 4 and
the like, thus lowering light extraction factor of the radiant
light, not allowing effective use of the radiant light, lowering
the lighting efficiency and adversely affecting the optimization of
light distribution.
[0037] According to the present embodiment, the lowering of light
extraction factor of the radiant light by the lighting circuit
components 4 and the like is reduced, and hence, the light LH
radiated from the side surface can be effectively used. For
example, when a reflector is used, the radiant light LH may be
radiated in a direction of a surface to be irradiated. In addition,
the light-emitting elements 3, the lighting circuit components 4
and the connector 5 for connecting with power supply are arranged
in a concentrated manner, and as a result, the wiring pattern of
the substrate 2 is shortened and simplified.
[0038] Further, since the light-emitting elements 3 as the heat
sources are not arranged at the central portion of the substrate 2,
and a rear surface side is formed as a flat heat dissipating
surface, when the heat dissipating surface is in contact with
another heat dissipating member, the heat is effectively
transmitted from the central portion of the substrate 2 to the rear
surface side, thereby easily realizing a configuration improving
the heat dissipation effects.
[0039] Furthermore, since a modular structure including the
connector 5 for connecting with power supply is achieved, a
lighting apparatus can be provided merely by incorporating the
substrate module 1 in the apparatus body and then connecting a
commercial power supply to the connector 5. Thus, the
light-emitting module 1 can be handled as a single common part
having a wide applicable field. Furthermore, since the connector 5
is arranged so that the connection opening 5a thereof is disposed
close to the outer peripheral edge of the substrate 2, the
connection with a power line of a commercial power supply is
readily made, and in addition, since the white resist is printed on
the mounting surface of the substrate 2, the excellent reflection
efficiency can be provided.
[0040] Hereunder, a first embodiment of a lighting apparatus
according to the present invention will be described with reference
to FIG. 4.
[0041] FIG. 4 is an illustration showing schematic structure of a
lighting apparatus. Referring to FIG. 4, a lighting apparatus 10
is, for example, a downlight and includes an apparatus body 11.
Included in the apparatus body 11 are a heat dissipating member 12
made of metal having heat dissipating fins, a light-emitting module
1 attached to the heat dissipating member 12, and a reflector 13.
The light-emitting module 1 is screwed to the heat dissipating
member 12 so that a heat dissipating surface on a rear surface side
2b of the substrate 2 is closely attached to the heat dissipating
member 12 through a silicon rubber sheet. Needless to say, this
mounting of the light-emitting module 1 may be made by means of
bonding or the like, instead of screw fastening. The reflector 13
has a shape of a bowl having a gently curved surface and has an
opening in its upper and lower ends. The upper end constitutes a
mounting opening 13a, and the lower end constitutes a radiating
opening 13b.
[0042] As for the positional relationship with the light-emitting
module 1, i.e., the positional relationship with the component
mounting surface of the substrate 2, the mounting opening 13a of
the reflector 13 is disposed so as to separate the light-emitting
elements 3 from the lighting circuit components 4 and the connector
5 for connecting with power supply, arranged around the
light-emitting elements 3. That is, the light-emitting elements 3
are divided from the lighting circuit components 4 and the like by
the reflector 13. Thus, the light radiated from the light-emitting
elements 3 is not interrupted by the lighting circuit components 4
and the like and is reflected on the reflector 13 and radiated
downward. Further, since the lighting circuit components 4 are not
seen from the front surface side of the reflector 13, the outer
appearance of the lighting apparatus 10 can be also improved.
[0043] According to the present embodiment, there is provided the
lighting apparatus 10 capable of achieving more effective
distribution of the radiant light from the light-emitting elements
3 in addition to the above described effects of the light-emitting
module 1.
[0044] The lighting apparatus is not limited to the above
embodiment, and the light-emitting module 1 may be mounted in a
light source having a cap, or may be incorporated in lighting
equipment used indoors or outdoors.
[0045] A second embodiment of the lighting apparatus according to
the present invention will be described hereunder with reference to
FIG. 5.
[0046] In this embodiment, a downlight type lighting apparatus,
using an electric-bulb shaped LED lamp as the light source, is
shown.
[0047] Referring to FIG. 5, the lighting apparatus mounted on a
ceiling surface includes an apparatus body 10 and a light source 20
having a shape of an electric bulb, mounted to the apparatus body
10.
[0048] The light source 20 includes: a light-emitting module 1
according to the first embodiment having the light-emitting
elements 3 mounted thereon; a main body 21 thermally coupled to the
light-emitting module 1 and working as a heat dissipating member;
and a glove 22 attached, through an insulating member, to the main
body 21 so as to cover, for example, a cap of E26 and the
light-emitting module 1.
[0049] The apparatus body 10 includes a. case 15 made of metal and
having a box-shaped structure having an opening in formed in a
lower surface thereof, and a reflector 16 made of metal fitted into
the opening of the case 15. The reflector 16 is formed by a metal
plate of aluminum or the like, for example, and a decorative frame
16a is formed to a peripheral portion of the lower surface of the
reflector 16. A socket 17, in which the cap of the light source 20
is screwed, is arranged at the center of an upper surface plate of
the reflector 16. The socket 17 is attached to the case 15 via a
support plate 18 secured to the inner side of the case 15.
[0050] According to the present embodiment, there is provided a
lighting apparatus with an LED lamp in the shape of an electric
bulb, which achieves the effects mentioned above with reference to
the light-emitting module 1.
[0051] A third embodiment of the lighting apparatus according to
the present invention will be described hereunder with reference to
FIG. 6. The like reference numerals are applied to portions or
elements corresponding to those of the second embodiment, and
repeated explanation thereof is omitted herein.
[0052] In this embodiment, there is provided a lighting apparatus
illustrated as a downlight, using a thin LED lamp, as a light
source 20, having thickness smaller in a height direction of
height. The light-emitting module 1 of the first embodiment is
mounted in the light source 20 in a similar manner, and a main body
21 functioning as a heat dissipating member is thermally coupled to
the light-emitting module 1. A cap is provided with a connecting
pin 25 formed into GX53-shape. A socket 17 is mounted to a case 15,
and connecting pins 25 for the cap are electrically and
mechanically connected to the socket 17.
[0053] According to the present embodiment described above, there
is provided a lighting apparatus with a thin-type LED lamp capable
of achieving the effects of the light-emitting module 1.
[0054] A modification of the light-emitting module according to the
first embodiment will be described hereunder with reference to FIG.
7. FIG. 7 is a plan view illustrating a light-emitting module. The
like reference numerals are added to portions or elements
corresponding to those of the first embodiment, and repeated
explanation thereof is omitted herein.
[0055] Lighting circuit components 4 are mounted on a component
mounting surface of a substrate 2 in a manner concentrated in the
central portion thereof. The lighting circuit components 4 include
a fuse F, a capacitor C, a rectifier REC, a constant voltage diode
ZD, resistors R1 and R2, and a transistor Q.
[0056] On the other hand, the light-emitting elements 3 are mounted
around the lighting circuit components 4 in a pattern spaced with a
predetermined interval from each other. In a connector 5 for power
supply connection is arranged so that a connection opening 5a
thereof is disposed close to the outer peripheral edge of the
substrate 2. In consideration of the connection with a power line,
although it is preferred that the connector 5 for the power supply
connection is disposed to a portion in the vicinity of the outer
periphery of the substrate 2, the connector may be arranged at the
central portion together with the lighting circuit component 4.
[0057] In this modified embodiment, the positional arrangement of
the light-emitting elements 3 and the lighting circuit components 4
of the first embodiment are reversed, and since the mounting
interval of the light-emitting elements 3 is greater than that of
the first embodiment, light LH radiated from the side surface of
the LED package can be effectively utilized as like as in the first
embodiment, and in addition, by increasing the interval between the
light-emitting elements 3, 3 . . . , the heat of the light-emitting
elements 3 can be transmitted and dissipated to the rear side of
the substrate 2 by effectively utilizing the entire structure of
the substrate 2.
[0058] Hereunder, there will be explained an embodiment, with
reference to FIGS. 8 to 13, in which the interval between the
plurality of light-emitting elements 3, 3, . . . mounted on the
substrate 2, and degree of luminance irregularity and variation in
light-emitting efficiency both dependent on the interval, have been
studied with respect to the light-emitting module 1 according to
the first embodiment.
[0059] Referring to FIG. 8, the light-emitting elements 3
constitute a surface-mounted LED package and are composed of a main
body 3a, an LED chip mounted on the main body 3a, and a translucent
resin 3b for sealing the LED chip, and this translucent resin 3b
functions as a light-emitting unit L.
[0060] The light-emitting unit L is, as illustrated in FIG. 8(a),
formed so as to have a substantially quadrate shape which is 2.8 mm
on a side (W) and about 4 mm on a diagonal (a). As illustrated in
FIG. 8(b), the light-emitting element 3 mounted on the substrate 2
is 1.5 mm in height (b) from the mounting surface of the substrate
2 to an upper surface of the light-emitting unit L and is 0.7 mm in
height (h) of the light-emitting unit L.
[0061] FIG. 9 is a graph showing a directional characteristics or
pattern of the light-emitting elements 3. The light-emitting
element 3 has a maximum illuminance in a direction perpendicular to
the upper surface, i.e., at a radiation angle of 0.degree., and as
for a direction of the side surface, has a illuminance 40 percent
or greater relative to the maximum illuminance at a radiation angle
of 80.degree. and a illuminance 50 percent or greater relative to
the maximum illuminance at a radiation angle of 70.degree., thus
radiating a given amount of light in a direction along the
component mounting surface.
[0062] The light-emitting elements 3 having such configuration and
characteristics were arranged in a pattern spaced at a
predetermined interval from each other as shown in FIG. 10.
Thereafter, luminance irregularity and light-emitting efficiency
were measured and evaluated by changing the interval.
[0063] Here, it was supposed, as illustrated in FIG. 10, that
character c denotes a minimum distance between the light-emitting
units L1 and L2, and character a denotes a width of the
light-emitting units L1 and L2 on a line of the minimum distance c.
The method of evaluating luminance irregularity was made such that
the light-emitting module 1 was made to glow at a height of 2.5 m
from the floor surface to illuminate the floor surface, and the
state of illumination on the floor was observed to perform visual
evaluation. This visual evaluation was, as illustrated in FIG. 11,
performed by observing illuminance distribution on the floor.
Further, FIG. 11 is a figure that schematically illustrates, with
the solid line, a boundary line at which illuminance difference
appears, more specifically, an image of light-emitting pattern
(mounting pattern image of the light-emitting elements 3) of the
light-emitting elements 3. Thus, the evaluation is ranked as
follows. In pattern A, luminance irregularity is not noticed at
all, in pattern B, luminance irregularity is hardly noticed, in
pattern C, luminance irregularity is noticed, and in pattern D,
luminance irregularity is clearly observed. Roughly speaking, when
the interval between the light-emitting units L of the
light-emitting elements 3 is small, the luminance irregularity may
be eliminated, the adjacent light-emitting elements 3 interrupt the
radiant light, thus lowering light emission efficiency. On the
other hand, when the interval between the light-emitting units L is
wide, the light emission efficiency becomes high, but the luminance
irregularity tends to occur.
[0064] As a result of the above evaluation and measurement,
evaluation and measurement values were obtained as shown in FIG.
12. Referring to FIG. 12, the abscissa indicates interval c between
the light-emitting units L of the light-emitting elements 3, and
the ordinate indicates luminance irregularity evaluation and
measurement values of light emission efficiency. Further, it was
found that as the interval c exceeded 4 mm, the luminance
irregularity gradually lowered and deteriorated and that as the
interval c increased, the light emission efficiency raised.
However, when the interval c exceeded 8 mm, it was found that the
light emission efficiency saturated.
[0065] In consideration of the above results, it was confirmed that
the permissible range of luminance irregularity lied around rank C,
and in consideration of the light emission efficiency, it was also
confirmed that the interval c between the light-emitting elements 3
was preferably greater than b and smaller than 4a (b<c<4a).
Furthermore, it was resulted that the optimum range in the above
range for further enhancing luminance irregularity evaluation and
improving the light emission efficiency was a range of
2b.ltoreq.c.ltoreq.3a. Still furthermore, in order to suppress
effect due to heat generation between the light-emitting elements
3, an optimum arrangement pattern was a<c. In the case of
a<c, the temperature of the light-emitting elements 3 during
glowing could be suppressed from rising. A lower limit value of the
above interval c may also be represented by height h of the
light-emitting unit L, and when this height h is used, a
relationship of approximately 2h<c, preferably, 4h.ltoreq.c will
be obtained.
[0066] In the above, the present embodiment, was described with
reference to as an example by considering the relationship between
the light-emitting units L1 and L2 of the light-emitting elements 3
illustrated in FIG. 10. However, for example, the dimensional
relationship of the interval c in the light-emitting units L2 and
L3 is similar to that of the light-emitting units L1 and L2. The
dimensions, the directional characteristics and the like of the
light-emitting elements 3 are not limited to the specific
dimensions and characteristics described with reference to this
embodiment. The mounting pattern of the light-emitting elements 3
is not limited to the pattern in which light-emitting elements 3
are, as illustrated in FIG. 10, arranged on the circumference, and
it may be sufficient that minimum distance c between the
light-emitting elements 3 falls into the above prescribed range.
For example, the light-emitting elements 3 may be arranged in a
matrix pattern.
[0067] A light-emitting element 30 illustrated in FIG. 13 may also
be used as the light-emitting element. This light-emitting element
30 is a surface-mounted LED package, and this LED package is
composed of a main body 30a formed of ceramics, a reflector 30d
arranged on the main body 30a, an LED chip 30c mounted in a recess
defined by the main body 30a and the reflector 30d, and a silicon
resin 30e for sealing the LED chip 30c. This silicon resin 30e
functions as the light-emitting unit L, and light is radiated from
the light-emitting unit L in a radial pattern which is similar, as
a whole, to the directional characteristics illustrated in FIG. 9,
including an upper surface direction and a direction along the
component mounting surface.
INDUSTRIAL APPLICABILITY
[0068] According to the present invention, there is provided a
light-emitting module having a wide applicable scope and improving
and optimizing the distribution of light radiated from the
light-emitting element. In addition, the heat dissipation effects
can be raised, and an effect of shortening and simplifying a wiring
pattern on a substrate can be also achieved.
* * * * *