JP2002343130A - Lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting fixture in which heat releasing effect is raised at the time of using an LED as a light emitting source. SOLUTION: Two or more LEDs are mounted in an under side 2a of a printed circuit board, and they radiate output light Lx in daylight color. Electronic parts for driving the LEDs are arranged in a domain of A along a circumference edge part in a top 2b of the printed circuit board. The printed circuit board is fixed to an upper cover and it is attached to a ceiling or the like. The generated heat from the LED conducted through the printed circuit board and the generated heat from the electronic parts are conducted to a lower cover 7 through the upper cover 6 of metal, and are dissipated in Ha, Hb, and the Hc directions. If a heat absorbing sheet 8 using a silicone sheet or the like, in which an opening 8a is formed, is used to cover the electronic products, heat can be radiated effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device having an enhanced heat radiation effect when a light emitting diode (hereinafter abbreviated as LED) is used as a light emitting source.

[0002]

2. Description of the Related Art Since LEDs emit red or green light, they have been used as LED lamps for indicator lights such as railway signals and displays of numbers and characters.
Recently, lighting fixtures using LEDs that emit light near daylight and using the LEDs as light sources have been developed.

FIG. 3 to FIG. 5 show an example of a lighting fixture using an LED as a light source. FIG. 3 is a plan view showing a state where many LEDs are mounted on one surface 2a of the printed circuit board. In FIG. 3, a large number of LEDs 3a and 3b are mounted on a disk-shaped printed circuit board 2a. The LEDs 3a are arranged on the printed circuit board 2a vertically long in the illustrated direction.

The LEDs 3b are arranged on the printed circuit board 2a horizontally long in the illustrated direction. The vertically long LEDs 3a and the horizontally long LEDs 3b are arranged on the printed circuit board 2a with good balance. Thus, by arranging the vertically long LEDs 3a and the horizontally long LEDs 3b in a well-balanced manner on the disc-shaped printed circuit board 2a, the light distribution characteristics of the lighting fixture become circular.

FIG. 4 is a plan view of a surface 2b opposite to the surface 2a of the printed circuit board. In FIG. 4, 4 is
Electronic components such as transistors, resistors and capacitors.
A control circuit for driving the EDs 3a and 3b is configured.
5a and 5b are lead terminals, which are wired from the power supply unit.
Connected to the wire. A large number of electronic components 4 are appropriately arranged on the circumference from the center to the peripheral edge of the printed circuit board 2b,
It is connected to a wiring layer (not shown) by a bonding process.

FIG. 5 is a schematic longitudinal sectional side view showing a state in which the lighting fixture 1 is attached to a fixed portion such as a ceiling. L is provided on one surface of the printed circuit board 2 of the lighting fixture 1, in the illustrated example, on the lower surface.
The EDs 3a and 3b are mounted. The electronic component 4 is arranged on the other surface of the printed circuit board 2, in the example shown in the figure, on the upper surface. 6
Is an upper cover provided with a hollow cylindrical portion 6a in the center, and is formed in a substantially circular dish shape and covers the side surface of the printed circuit board 2.

The lead terminals 5a and 5b provided on the upper surface of the printed circuit board 2 are connected to lead wires 5x and 5y through a connector 5p. Lead wire 5x, 5y
Is drawn out to the ceiling 9 through the hollow cylindrical portion 6a and connected to a power supply unit installed on the ceiling. Reference numeral 7 denotes a circular lower cover having an open central portion, which has a threaded portion formed on the inner periphery thereof, and which is formed on the outer periphery of the upper cover 6 at a position lower than the upper surface of the printed circuit board 2. It is engaged with the part 6b.

[0008] The upper cover 6 and the lower cover 7 may be engaged by other means. For example, the upper cover 6 and the lower cover
It is also possible to provide a protrusion on any one of 7 and form an engagement hole for engaging with the protrusion on the other. Upper cover-6
The lower cover 7 and the lower cover 7 are both formed of a lightweight metal having good thermal conductivity such as aluminum.

[0009] 10a, 10b, the upper cover 6 to the ceiling 9
It is a screw to fix to. Also, 11 is the LED 3a, 3
The cover is made of an acrylic cylindrical cover that covers the surface b. A convex lens 11a is formed on the surface. Reference numeral 12 denotes an acrylic cover that covers the electronic component 4 and is formed in a hollow disk shape. Since the acrylic cover 12 is inserted inside the upper surface of the cylindrical cover 11, the acrylic cover 12 is prevented from moving in the horizontal direction.

Since the convex lens 11a is formed on the cylindrical cover 11, the output light from the LEDs 3a and 3b is efficiently condensed by the convex lens 11a and irradiated to the outside. The lower cover 7 has a flange portion 7a formed at the tip thereof to hold the cylindrical cover 11 and to light up the LEDs 3a, 3b.
The output light from is not diffused. That is,
The lower cover 7 has a function of holding the printed circuit board 2.

When mounting the lighting fixture 1 shown in FIG. 5, the upper cover 6 is fixed to the ceiling 9 with screws 10a and 10b. The printed circuit board 2 is made up of a cylindrical cover 11 and an acrylic cover.
The lead terminals 5a and 5b are connected to the lead wires 5x and 5y through the connector 5p. Next, the cylindrical cover 11 is held by the flange 7a of the lower cover 7, and the lower cover 7 is held.
7 and the upper cover 6 are engaged.

The operating voltage of a normal LED used for a display or the like is, for example, 1.7V. The LED used as the light source of the lighting fixture has an operating voltage of, for example, 3.6 V in order to achieve high luminance, and uses a higher voltage than the operating voltage of a normal LED. Therefore, when used as a light source for lighting equipment,
Heat generated during LED operation increases. Operating an LED in a high-temperature state causes a failure and shortens its life. Therefore, it is necessary to efficiently radiate the heat generated from the LED to the outside.

As shown in FIG. 5, in the conventional lighting apparatus, the LEDs 3a and 3b are mounted on the lower surface of the printed circuit board 2.
The heat generated from b goes upward through the printed circuit board 2. However, a large number of electronic components 4 used in a control circuit for driving the LEDs 3a and 3b are arranged on the circumference from the center to the periphery of the printed circuit board 2.

For this reason, when the lighting fixture 1 is mounted on the ceiling surface 9 as shown in FIG. 5, the heat generated from the LEDs transmitted upward through the printed board and the electronic components arranged on the printed board are reduced. The generated heat goes upward, but is blocked by the ceiling surface, and is not sufficiently radiated to the outside.

[0015]

Therefore, the LED 3
When the LEDs 3a and 3b are operating, the heat radiation from the printed circuit board 2 is not sufficient, so that the LEDs 3a and 3b are in a high temperature state. there were.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide a lighting fixture having an improved heat radiation effect when an LED is used as a light source.

[0017]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lighting apparatus according to the first aspect, wherein a plurality of light emitting diodes (LEDs) are mounted on one surface, and the luminaires are arranged along a peripheral portion of the other surface. A printed circuit board on which electronic components for driving the LEDs are disposed, an upper cover attached to a fixing portion for covering a side surface of the printed circuit board, and the printed circuit board held by being engaged with an outer periphery of the upper cover. A lower cover having an opening on an output light irradiation surface of the LED;
In addition, heat generated from electronic components is radiated to the outside from the upper cover and the lower cover.

According to a second aspect of the present invention, in the luminaire according to the first aspect, a heat absorbing sheet for covering the electronic components arranged on the printed circuit board is provided.

According to a third aspect of the present invention, in the lighting apparatus according to the first or second aspect, the lower cover has one end positioned above a position of an electronic component disposed on a printed circuit board. The opening is formed by providing a flange at the other end.

According to the above feature of the invention according to claim 1,
Electronic components for driving the LEDs are arranged along the periphery of the printed circuit board, and are not arranged at the center. For this reason, the amount of heat retained in the center of the printed circuit board can be reduced. And the LED transmitted through the printed circuit board
The heat generated from the electronic component and the heat generated from the electronic components are radiated from the upper cover and the lower cover provided on the side surface of the printed circuit board. For this reason, the temperature rise of the LED is reduced, malfunctions and failures are prevented from occurring, and the life can be extended.

According to the above feature of the invention according to claim 2,
Electronic components are covered with an endothermic sheet. Therefore, LED
In addition, heat generated from the electronic components can be effectively absorbed and radiated to the outside.

According to the above feature of the invention according to claim 3,
The lower cover has one end extending above the position of the electronic component disposed on the printed circuit board and the other end provided with a flange to form the opening. For this reason, the heat radiation area of the heat generated from the LEDs and electronic components mounted on the printed circuit board increases, and the heat radiation efficiency improves.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view showing an example of the electronic component 4 arranged on one surface (upper surface) 2b of the printed circuit board. In FIG. 2, the electronic component 4 is not arranged at the center of the one surface 2b of the printed circuit board, but is arranged concentrically only at the periphery.

FIG. 1 is an explanatory diagram showing the state of heat radiation from the printed circuit board during LED operation. The cylindrical cover 11 and the acrylic cover 12 described with reference to FIG. 5 are not shown for simplicity. In FIG. 1, a printed circuit board 2
The region A in b is a portion where the electronic component 4 described in FIG. 2 is arranged. One end of the lower cover 7 extends to a position above the printed circuit board 2b on which the electronic component 4 is disposed, and is engaged with the upper cover 6.

Since the upper cover 6 and the lower cover 7 are made of a metal such as aluminum having a good thermal conductivity as described above, they form a heat radiation path. As described above, the flange 7a is formed at the other end of the lower cover 7, and the output light Lx is emitted from the opening of the lower cover 7.

In the examples shown in FIGS. 1 and 2, the electronic components 4 are not arranged at the center of the printed circuit board 2b, but are arranged concentrically only in the region A along the peripheral edge. Therefore, LED
Operates, and when the output light is irradiated in the Lx direction, the LED
The heat generated from the electronic component 4 and the heat generated from the electronic component 4 are directed toward a heat radiation path formed on the side surface of the printed circuit board 2b and formed by the upper cover 6 and the lower cover 7 having a small thermal resistance, near the center of the printed circuit board 2b. The amount of heat stored is reduced.

Even if heat dissipation upward from the central portion of the printed circuit board 2b and the area A along the peripheral edge of the printed circuit board 2b is blocked by the ceiling, the side faces toward the cylindrical portion of the upper cover 6 Heat moves in the direction. For this reason, heat is transferred from the upper cover 6 to the lower cover 7, and finally the heat is radiated from the outer surface of the lower cover 7 in the Ha direction. Part of the heat dissipation is also performed from above the upper cover 6.

As described above, the heat generated from the LED and the electronic components is effectively dissipated to the outside from the upper cover and the lower cover, so that heat is not stored around the LED. Therefore, the temperature rise of the LED is reduced, so that malfunction is prevented and the life can be extended.

Further, the heat is transferred to the lower cylindrical portion of the lower cover 7 and dissipated in the Hb direction. Further, the lower cover 7
Is also transferred to the flange 7a formed at the lower part of
Heat is also dissipated in the c direction. As described above, the lower cover 7 is engaged with the upper cover 6 at a position above the printed circuit board 2b on which the electronic components are arranged, and the heat generated by the LEDs and the electronic components is dissipated from the lower cover 7 by heat. I have. Therefore, L
The heat radiation area of the heat generated from the ED and the electronic components increases, and the heat radiation effect improves.

As shown in FIG. 5, when the lower cover 7 is engaged with the upper cover 6 below the upper surface of the printed circuit board 2, the heat radiation from the upper surface of the printed circuit board 2 is mostly upward. Since the heat is transmitted from the side of the cover 6, the amount of heat transmitted to the lower cover 7 is reduced. Therefore, the amount of heat radiation from the lower cover 7 is reduced.

In some cases, the luminaire 1 using an LED as a light source has a configuration in which a recess is formed in the ceiling surface, and the upper portion of the luminaire 1 is disposed in the recess. In such a case, if the heat radiation from the side surface of the upper cover 6 is increased as described above, the heat radiation is hindered by the peripheral wall of the depression, and the heat radiation effect is reduced.

In the present invention, as shown in FIG.
7 extends above the position of the electronic component 4 arranged on the printed circuit board 2. For this reason, even if the heat radiation in the Ha direction in FIG. 1 is blocked by the peripheral wall of the depression, the heat moves below the lower cover 7 having a small thermal resistance, and the Hb direction and the H
Heat can be effectively dissipated from the direction c.

In FIG. 1, reference numeral 8 denotes a disk-shaped heat radiation sheet having an opening 8a formed in the center. The heat radiation sheet 8
For example, a material having a good heat absorption property such as a silicon sheet is used, and is attached on the electronic component. The heat radiation sheet 8 absorbs heat generated from the LED and the electronic components.
The heat absorbed by the heat radiating sheet 8 is transferred to the lower cover 7 through the upper cover 6 as described above, and the lower cover 7 is transferred.
7, heat is dissipated in the directions of Ha, Hb and Hc.

The outer diameter of the heat radiation sheet 8 is the same as the outer diameter of the printed circuit board 2. The diameter of the opening 8a formed in the heat radiation sheet 8 is slightly smaller than the inner diameter of the area A where the electronic components are arranged on the printed circuit board 2b.
In addition, through holes may be formed in portions corresponding to the lead terminals 5a and 5b of the heat radiation sheet 8 so as to have the same size as the printed circuit board 2. By attaching such a heat radiation sheet 8 from above the electronic component, the heat generated from the LED and the electronic component can be efficiently absorbed and dissipated from the outer surface of the lower cover 7.

In the above-described example, a circular light distribution characteristic is obtained by making the printed circuit board of a lighting apparatus using an LED as a light emitting source circular. The printed circuit board of the present invention may have a rectangular shape. In this case, the upper cover 6, the lower cover 7, and the cylindrical cover 11 covering the LEDs
Is constituted by a tubular body having a rectangular shape in cross section. Even in such a case, by arranging the electronic components along the periphery of the four sides of the printed circuit board except for the central part of the printed circuit board, the same as in the case of using a circular printed circuit board,
D and the heat generated from the electronic component can be satisfactorily dissipated.

[0036]

As described above, according to the first aspect of the present invention, the electronic components for driving the LEDs are arranged along the periphery of the printed circuit board, and are arranged at the center. Not. For this reason, the amount of heat retained in the center of the printed circuit board can be reduced. The heat generated from the LEDs and the heat generated from the electronic components transmitted through the printed circuit board are radiated from the upper cover and the lower cover provided on the side surface of the printed circuit board. Therefore, LED
Temperature rise, malfunctions and failures can be prevented, and the life can be prolonged.

According to the above feature of the invention according to claim 2,
Electronic components are covered with an endothermic sheet. Therefore, LED
In addition, heat generated from the electronic components can be effectively absorbed and radiated to the outside.

According to the above feature of the invention according to claim 3,
The lower cover has one end extending above the position of the electronic component disposed on the printed circuit board and the other end provided with a flange to form the opening. For this reason, the heat radiation area of the heat generated from the LEDs and electronic components mounted on the printed circuit board increases, and the heat radiation efficiency improves.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing heat dissipation of a lighting device according to an embodiment of the present invention.

FIG. 2 is a plan view showing an example in which electronic components are arranged on a printed circuit board.

FIG. 3 is a plan view showing a state where LEDs are mounted on one surface of a printed circuit board.

FIG. 4 is a plan view showing a conventional example in which electronic components are arranged on the other surface of a printed board.

FIG. 5 is a schematic vertical sectional side view showing a state in which a conventional lighting fixture is mounted on a ceiling.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lighting fixture 2 Printed circuit board 3 LED 4 Electronic component 5a, 5b Lead terminal 5x, 5y lead wire 6 Upper cover 7 Lower cover 8 Heat absorption sheet 9 Ceiling 11 Cylindrical cover 11a Convex lens 12 Acrylic cover

Claims (3)

[Claims] 1. A plurality of light emitting diodes (LEDs) on one surface
A printed circuit board on which electronic components for driving the LEDs are arranged along the peripheral edge of the other surface; and an upper cover attached to a fixed portion and covering a side surface of the printed circuit board.
And a lower cover engaged with the outer periphery of the upper cover to hold the printed circuit board and having an opening on an output light irradiation surface of the LED. A lighting device characterized in that heat is radiated to the outside from an upper cover and a lower cover. 2. An endothermic sheet for covering an electronic component disposed on the printed circuit board.
The lighting fixture according to 1. 3. The lower cover has one end extending above a position of an electronic component disposed on a printed circuit board,
The lighting device according to claim 1, wherein a flange is provided at the other end to form the opening.