KR100367182B1 - LED Lamp - Google Patents

Abstract

The present invention relates to a light emitting diode lamp, and more particularly to a structure of an LED lamp that can increase the ratio of the beam width to the horizontal direction and the vertical direction,

an LED chip having p-type and n-type electrodes and emitting photons in accordance with a forward current applied through both electrodes;

An anode and a cathode connected to two electrodes of the LED chip and drawn out to apply an external current;

A reflection cup having the LED chip mounted thereon, and having an oval-shaped truncated conical bottom surface;

A lens is formed to encapsulate the cathode and the anode portion and the reflective cup and the LED chip, and the lens has an oblong circular lens in a horizontal section;

The uniaxial direction of the ovoid bottom of the reflective cup is characterized in that it is configured to be parallel to the long axis direction of the ovoid horizontal cross section of the lens.

Description

Light Emitting Diode Lamp {LED Lamp}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode lamp, and more particularly, to a structure of an LED lamp capable of increasing a ratio of beam widths to a horizontal direction and a vertical direction.

In general, when a forward current is applied to a diode chip of a pn junction structure, electrons and holes accumulate in the active region of the chip and recombine to form photons having an energy corresponding to the bandgap energy of the active region. Is released.

This phenomenon is called injection type electroluminescence, and a light emitting device using the same is called a light emitting diode.

The structure of a general light emitting diode lamp is as shown in Figs. 1A, 1B and 1C and the LED chip 1 is attached to the bottom of the reflective cup 3a, which is usually plated with silver, with a conductive adhesive 6 on it. The p-type electrode and the n-type electrode formed on a part of the body of the LED chip 1 are connected to the anode 2 and the cathode 3 through the bond wire 5 or the reflection cup 3a, respectively. In addition, the LED chip 1 and the reflection cup 3a are molded to be encapsulated by a colorless or colored light-transmissive resin. Since the molding of the light-transmissive resin is usually in the form of a dome, the lens 4 ) Will also play a role.

Most of the photons emitted from the LED chip 1 enter the interface between the lens 4 and the air either directly or via reflection in the reflecting cup 3a, where the photons are constant, determined by the angle of incidence at the interface. It is refracted at an angle and escapes out of the lamp. The intensity of photons emitted out of the light emitting diode lamp shows the inherent distribution of the lamp along the emission direction, which is usually called the far-field photon distribution pattern.

Such light emitting diode lamps have been generally used for various display devices and electronic displays due to their long lifespan, high reliability, strong vibration, and low power consumption. Recently, high-brightness LED lamps exceed the brightness of incandescent lamps. As it emerged, it was used for general lighting fields including traffic lights.

One of the important characteristics that must be considered in most LED lamp applications is the far-field photon distribution pattern of the LED lamp.

In general, LED lamps vary greatly in the far-field pattern required for their application.

For example, in the case of a display board installed in a large stadium, the viewing angle in the vertical direction may be relatively narrow, but the viewing angle in the horizontal direction should be about 120o.

Therefore, when implementing the display board using the LED lamp, the most preferable beam width of the LED lamp preferably has a characteristic that can easily satisfy the viewing angle characteristics required in the display board.

If the beam width characteristic of the lamp is largely out of line with the viewing angle characteristic required in the display board, there are problems such as unnecessary loss of light output or an increase in the number of required lamps and a complicated pixel structure.

The present invention is to solve the above problems in the application of the LED lamp, and in particular, to provide an LED lamp that can increase the ratio of the beam width (beam width) to the horizontal direction and the vertical direction.

As a means for achieving the above object,

an LED chip having p-type and n-type electrodes and emitting light according to a forward current applied through both electrodes;

An anode and a cathode connected to each electrode of the LED chip and drawn out to enable application of an external current;

A reflection cup having a bottomed conical structure mounted on a lower portion of the LED chip and having an oval shape in a horizontal cross section for reflecting the generated photons in an upward direction;

A lens is molded to enclose a portion of the reflective cup, the cathode and the anode, and the reflective cup and the LED chip, the lens having an oval horizontal cross section for refracting the traveling direction of photons;

It characterized in that the minor axis direction of the oval-shaped bottom surface of the reflecting cup is arranged in parallel with the long axis direction of the oval-shaped horizontal cross section of the lens.

In addition, the LED chip is characterized in that the diagonal direction of the horizontal section is configured to be parallel to the long axis or short axis direction of the oval-shaped horizontal section of the lens.

In addition, the LED chip has a rhombus shape in which the axial lengths of the horizontal cross sections are different from each other, and the short axis diagonal direction of the horizontal cross sections is parallel to the long axis direction of the ovoid horizontal cross section of the lens.

In addition, the LED chip has a rhombus shape in which the axial length of the horizontal cross section is different from each other, and the short axis of the horizontal cross section is configured to be parallel to the short axis of the ovoid horizontal cross section of the lens.

Figure 1a is a perspective view showing the appearance of a typical light emitting diode lamp.

Figure 1b is a vertical cross-sectional view of a typical light emitting diode lamp.

1C is a view illustrating a structure of a lens, a reflecting cup, and a chip portion of a typical light emitting diode lamp.

Figure 2a is a perspective view of a reflective cup of a typical light emitting diode lamp.

2B is a plan view of a reflective cup having an oval shape at the bottom;

2C is an illustration of the inclination along the direction of the side of the reflecting cup.

3A is a perspective view of a lens of a typical light emitting diode lamp.

FIG. 3B is a vertical cross-sectional view of FIG. 3A in the x-axis direction. FIG.

3C is a vertical sectional view along the y axis of FIG. 3A.

Figure 4a is a plan view of the chip and reflector cup and lens portion structure of a typical light emitting diode lamp.

4B is a plan view of a chip, reflector cup and lens portion structure of the LED lamp of the present invention;

4C is a plan view of a chip and reflective cup and lens portion embodiment of a typical light emitting diode lamp.

Figure 5a is a plan view showing an example in which the diagonal direction of the horizontal cross section of the chip coincides with the long axis direction of the horizontal cross section of the lens in the LED lamp of the present invention.

Figure 5b is a plan view showing an example in which the horizontal cross section of the chip in the light emitting diode lamp of the present invention and the short axis direction coincides with the long axis direction of the lens horizontal cross section.

Figure 5c is a plan view showing an example in which the horizontal cross section of the chip in the light emitting diode lamp of the present invention and the short axis direction coincides with the short axis direction of the lens horizontal cross section.

FIG. 6A is a far-field pattern of the intensity of output photons of a light emitting diode lamp having the structure of FIG. 4A; FIG.

6B is a far-field distribution diagram of the intensity of output photons of a light emitting diode lamp having the structure of FIG. 4B;

6C is a far-field distribution diagram of the intensity of output photons of a light emitting diode lamp having the structure of FIG. 4C;

7A is a far-field distribution diagram of the intensity of output photons of a light emitting diode lamp having the structure of FIG. 5A;

FIG. 7B is a far-field distribution diagram of the intensity of output photons of a light emitting diode lamp having the structure of FIG. 5B; FIG.

FIG. 7C is a far field distribution diagram of the intensity of output photons of a light emitting diode lamp having the structure of FIG. 5C; FIG.

8A is a horizontal plane far field distribution of the intensity of photons emitted from an LED chip of square structure;

Fig. 8B is a horizontal far field distribution diagram of the intensity of photons emitted from a rhombus pillar chip having a diagonal of one side of a horizontal section.

Explanation of symbols on the main parts of the drawings

1: LED chip 2: anode

3: cathode 3a: reflective cup

4: Lands 5: Bondwire

Hereinafter, the present invention will be described in more detail with reference to the drawings.

And, if necessary, the prior art to be compared with the present invention will be described to more clearly the present invention.

The biggest feature of the present invention is that the bottom of the reflective cup is oval, and the minor axis of the oval bottom of the reflective cup is parallel with the long axis of the oval horizontal cross section of the lens.

That is, generally, a reflecting cup applied to a diode has a conical structure. The reflecting cup used in the present invention has a circular bottom instead of a circular shape as shown in FIGS. 2A, 2B, and 2C. Its characteristic is that it has an oval structure.

That is, FIG. 2A is a perspective view of the reflection cup, FIG. 2B is a plan view, and FIG. 2C is a comparison between the inclination angles in the x-axis direction and the y-axis direction of the side of the reflection cup.

Sides of the reflective cups are generally inclined at a predetermined angle so that the area of the horizontal cross section of the cups increases upward. As shown in FIG. 2C, the inclination of the side faces may vary depending on the direction.

For example, differentiation of the focusing effect on photons incident in each direction can be made by differentiating the inclination of the side surfaces with respect to the long axis direction and the short axis direction of the oval-shaped bottom surface of the reflective cup.

In the case of an oval-shaped pyramid-shaped reflecting cup whose bottom surface is picked up in an oval shape, unlike a cone-shaped reflecting cup, the focusing effect on incident light from the side of the cup varies greatly depending on the region.

That is, the photon incident on the concave region (region a in FIG. 2B) with a large curvature of the side along the long axis of the oval cross section of the cup is given a very large focusing effect, but the uniaxial direction of the cup's oval cross section. Therefore, the focusing effect on the photons incident on the obtuse region (region b of FIG. 2B) decreases relatively.

Meanwhile, another factor directly affecting the far-field pattern of the LED lamp may include the LED lens shown in FIG. 3, where FIG. 3B is a vertical cross-sectional view of the x-axis in FIG. 3A. 3C is a vertical cross-sectional view of the y-axis direction of FIG. 3A.

In general, in order to change the beam width in the horizontal direction and the vertical direction of the LED lamp, it is common to use a lens having an oval shape instead of a circular cross section as shown.

In this type of lens, the curvature of the lens dome surface varies depending on the direction. That is, since the curvature of the lens surface in the long axis direction of the oval-shaped horizontal cross section is relatively smaller than the curvature of the lens surface in the short axis direction, the focusing effect of the lens on the incident light is greatly reduced in the long axis direction. As a result, the far-filed pattern of the LED lamp is characterized in that the beam width in the long axis direction of the lens is greatly enlarged compared to the beam width in the short axis direction.

4 and 5 show plan views seen from the top of the LED lamp.

Figure 4a shows the structure used in the existing oval-shaped LED lamps. Its characteristic is that it uses a cone-shaped reflecting cup.

In this case, the difference between the beam widths in the long axis direction and the short axis direction of the lens is determined by the change in curvature of the lens dome plane.

On the contrary, in the structure of FIG. 4B proposed by the present invention, the reflective cup having an oval-shaped truncated conical structure is used instead of the circular shape of the reflective cup.

In this case, differentiation of the beam width with respect to the long axis direction and the short axis direction of the lens is influenced not only by the structure of the lens but also by the cup structure, thereby increasing the difference in the beam width between the long axis direction and the short axis direction.

More specifically, in the case of using a cup of conical shape, as described above, the focusing effect is strongly observed for photons incident on the concave region (a region in the drawing) of the side of the cup. The focusing effect is weakened for photons incident on an obtuse region (b region in the figure) of the cup side. Therefore, as shown in FIG. 4B, when the long axis direction of the horizontal cross section of the cup in which the focusing effect is large in the cup coincides with the short axis direction of the horizontal cross section of the lens in which the focusing effect is large in the lens, the focusing of the cup and the lens is performed. The beam width in the short axis direction of the lens in which the effects have been enhanced is significantly narrowed, and the beam width in the long axis direction of the lens in which the focusing effect of the cup and the lens is weakened is significantly narrowed, thereby reducing the ratio of beam widths in both directions. It can grow.

6A and 6B show the theoretically calculated far-field pattern obtained from the structures of FIGS. 4A and 4B, respectively. In the case of the structure of FIG. 4B, the longitudinal and minor directions of the lens are shown. It can be seen that the ratio of beamwidth to vertical is much higher than in the case of the structure of FIG. 4A.

The structure of FIG. 4C is the same as that of FIG. 4B in that a reflective cup having a conical shape is used, but has an important difference.

That is, unlike in FIG. 4B, since the short axis direction of the lens and the short direction of the refracting cup are in the same direction, the space margin in which the reflective cup can be accommodated is large in the lens, which is advantageous in manufacturing. 6c, there is a problem in that the difference in beam width in the long axis direction and the short axis direction of the lens is significantly reduced.

The reason why the beam width difference between the two directions of the lens in the structure of FIG. 4C is greatly reduced is that the concave region of the reflecting cup in which the strong focus is shown in the cup lies in the long axis direction of the lens in which the focus is weak in the lens. This is because the focusing effect on the side of the cup with respect to the photons emitted in the long axis direction of the lens is not weakened and is enhanced, so that the beam width in the long axis direction of the lens is significantly reduced.

One thing to note here is that the focusing effect on the reflecting cups for photons emitted in the shortening direction of the lens by increasing the inclination of the side of the cup with respect to the shortening direction of the lens even when the bottom of the reflecting cup is circular as in the structure of FIG. 4A. In this case, however, the radius of the cup relative to the short axis direction of the lens decreases as the upper portion of the cup increases, so that the concave region on the side of the cup, which exhibits a strong focusing effect on photons, moves in the long axis direction of the lens. As a result, the problem is reduced to the structure shown in Figure 4c.

On the other hand, as in the structure of FIG. 4B belonging to the present invention, in the conical reflection cup, the inclination of the cup side surface relative to the short axis direction of the lens is relatively small because the radius at the bottom starts with a large value for the short axis direction of the lens. Even if it is raised, the concave area on the side of the cup at the top of the cup can be prevented from moving in the long axis direction of the lens.

The structure of the lamp shown in FIG. 5 is also proposed by the present invention. The difference from the structure of FIG. 4B is that the chip is rotated so that the diagonal direction of the horizontal cross-section of the LED chip is parallel to the long axis direction or the short axis direction of the lens. In particular, in the structures of FIGS. 5B and 5C, the LED chip is deformed into a diamond shape instead of the existing square structure.

In general, when designing an LED lamp, the emission pattern of the output photons of the chip itself is usually not considered much, but since the emission of photons starts from the LED chip itself, the emission of the chip-specific photons in the design of the lamp Considering patterns can have important meanings.

8A and 8B show a change according to the emission direction of the intensity of photons emitted in a direction parallel to the junction plane, ie, in a horizontal direction, among photons emitted from a square chip and a rhombus pillar chip, respectively.

In the case of a square chip mainly used in a general LED lamp, the intensity of photons is slightly higher in the diagonal direction of the square, which is a horizontal section of the chip, but the photons are generally emitted relatively evenly in all directions on the horizontal plane.

On the other hand, in the case of the chip in which the horizontal cross section of the LED chip is transformed into a rhombus shape instead of the conventional square, the intensity of photons is very high in the short diagonal direction of the diamond, which is the horizontal cross section of the chip, while in the long axis diagonal direction of the chip cross section rhombus. Shows low characteristics.

Since the emission pattern of the photons emitted from the chip varies greatly depending on the geometry of the chip, in order to design an LED lamp well, the geometry of the chip as well as the horizontal plane of the chip based on the reflective cup or the LED lens It is also desirable to consider relative rotation angles.

When the diagonal direction of the horizontal cross section of the chip is parallel with the long axis direction or the short axis direction of the lens as in the structure of FIG. 5A, compared to the case of the structure of FIG. 4A, more photons are directed toward the long axis direction or the short axis direction of the lens. Since it is emitted toward the surface, there may be an advantage that the design effect of the cup and the lens in these directions appears to be relatively highlighted (see FIG. 7A).

In particular, when the uniaxial diagonal direction of the LED chip cross-section coincides with the long axis direction of the lens as in the structure of FIG. 5B, the focusing effect on the reflecting cup and the lens for more photons emitted in this direction may be reduced. As shown in 7b, the beam width in the long axis direction of the lens is maximized.

On the other hand, when the short diagonal direction of the LED chip cross section coincides with the short axis direction of the lens as in the structure of FIG. 5C, the focusing effect on the reflecting cup and the lens for more photons emitted in this direction is increased simultaneously. As shown in Fig. 2, the beam width in the short axis direction of the lens is greatly reduced.

As described above, even if only the relative angle of rotation of the reflecting cup or the chip on the horizontal plane of the lens is changed, the far-field pattern is effectively changed. Therefore, various applications in FIGS. It is easy to implement the far-field pattern required by.

As described above, the present invention provides an effect of manufacturing an LED lamp that can increase a ratio of a beam width to a horizontal direction and a vertical direction in manufacturing a light emitting lamp.

In particular, the production of molds for making reflective cups or lenses is very expensive, and it is appropriate to take advantage of the fact that the far-field pattern changes significantly even if only the relative rotation angle of the chip or reflective cup is changed. In this case, it is expected to reduce the cost significantly.

Claims (5)

an LED chip having p-type and n-type electrodes and emitting photons in accordance with a forward current applied through both electrodes; An anode and a cathode connected to two electrodes of the LED chip and drawn out to apply an external current; A reflection cup having the LED chip mounted thereon, and having an oval-shaped truncated conical bottom surface; A lens is formed to encapsulate the cathode and the anode portion and the reflective cup and the LED chip, and the lens has an oblong circular lens in a horizontal section; Light-emitting diode lamp, characterized in that the minor axis direction of the oval-shaped bottom surface of the reflective cup is arranged in parallel with the long axis direction of the oval-shaped horizontal cross-section of the lens. The method of claim 1, The LED chip is a light emitting diode lamp, characterized in that the direction toward the side of the side is configured to be parallel to the long axis or short axis direction of the horizontal cross section of the lens. The method of claim 1, The LED chip is a light-emitting diode lamp, characterized in that configured so that the diagonal line of the horizontal cross-section parallel to the long axis or short axis direction of the lens. The method of claim 1, The LED chip has a rhombus shape in which the axial lengths of the horizontal cross sections are different from each other, and the short axis of the horizontal cross sections is parallel to the long axis direction of the lens. The method of claim 1, The LED chip has a rhombus shape in which the axial lengths of the horizontal cross sections are different from each other, and the short axis of the horizontal cross sections is parallel to the short axis direction of the lens.