JP2000223751A - Led lamp and display device using the led lamp - Google Patents

Abstract

(57) Abstract: L that suppresses or utilizes light emission unevenness that occurs in a light emitting chip having a pair of positive and negative electrodes, on which a nitride semiconductor is stacked and including a light-transmitting electrode on the same surface side.
An ED lamp is provided. SOLUTION: An L formed by molding a rectangular light emitting chip with an elliptical resin lens as viewed from the light emission observation surface side.
In the ED lamp, the light emitting chip is formed by stacking a nitride semiconductor, and a direction connecting a pair of positive and negative electrodes including at least a translucent electrode on the same surface side is substantially perpendicular to a major axis direction of the ellipse. By molding the light emitting chip, deterioration of the directional characteristics due to uneven light emission of the light emitting chip, which has been a problem in the conventional LED lamp, is prevented, and furthermore, it works properly. In addition, a display device obtained by using the same provides a favorable viewing angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode which emits light using an LED chip, and more particularly to a light emitting diode having excellent visibility and color mixing even in a distant place and a near place, and a display device using the same.

[0002]

2. Description of the Related Art Generally, an LED lamp has a light emitting chip molded into a lens shape with a resin such as epoxy.
The lens shape is a circular resin lens as viewed from the light emission observation surface side of the LED lamp, and is a so-called shell-shaped lens shape. The resin lens is adjusted to a desired viewing angle and used as a light source for various devices.

On the other hand, an LED lamp having an elliptical lens shape as viewed from a light emission observation surface is known in order to widen a viewing angle in a horizontal direction (horizontal direction), separately from the above-mentioned shell-type LED lamp. For example, the LED lamp is disclosed in Japanese Utility Model Laid-Open No. 6-79166.

FIG. 4 is a plan view of a conventional LED lamp molded with an elliptical lens as viewed from a light emission observation surface side. The rectangular light emitting chip 51 is mounted on the center of the reflecting mirror of the lead frame 53 having the concave reflecting mirror.
One of the electrodes is wire-bonded from the center of the light emitting chip 51 with a gold wire 54 to form another lead frame 53 '.
Is electrically connected to The other electrode is connected by bonding the substrate of the light emitting chip 51 and the lead frame 53 with a conductive material. Further, the lead frames 53 and 53 ′ on which the light emitting chips 51 are mounted are made of resin 5.
2 is molded in an elliptical shape. By molding the light emitting chip with an elliptical lens in this manner, it is possible to widen the viewing angle in the horizontal direction (the major axis direction of the ellipse).

The objective of the elliptical lens is to increase the viewing angle in the horizontal direction (the major axis direction of the ellipse), that is, in the horizontal direction. Therefore, the shape of the light-emitting chip, the size of the light-emitting surface, the shape, and other factors, along with the design of the elliptical lens
This is very important in determining the viewing angle.

[0006] Incidentally, LED lamps have various uses, and the driving conditions are different depending on them. In a nitride semiconductor light emitting device, it is used for a large display as a blue or green LED, and a light emitting device having characteristics specific to the device is required. The display is lit by arranging a plurality of LEDs vertically and horizontally. As a method, there are a dynamic lighting method in which the LEDs are divided into a plurality of sets and lighting is performed in a time-division manner, and a static method in which the LEDs are simultaneously lit without division. The driving conditions are determined by these lighting methods and display devices.

[0007] In addition, such displays are usually installed on a wall surface, indoors or outdoors, and the display device is provided to the observer with respect to the height position for the purpose of distance to the observer and number of people. On the other hand, it is installed above. At this time, in the directional characteristics of the light emission of the LED and the spread of the light emission in the vertical and horizontal directions, it is unnecessary to emit light upward in the vertical (vertical) spread.

[0008]

As shown in FIGS. 5 and 6, a transparent electrode is provided on almost the entire surface of a nitride semiconductor light emitting device which has been put to practical use so as to cover a p-type layer. However, in such an element structure, since the sheet resistance of the nitride semiconductor is higher than that of the transparent electrode, when a large current is applied, the flow of A takes priority over the flow of B in the figure, and the current is biased toward A. This tendency is observed even when the amount of flow and current is small.
For this reason, as shown in FIG. 5, the light emission of the element occurs in a region 5 ′ where the light intensity is high, causing unevenness.

In the above-described dynamic lighting method, the LED lamp used for the display is lit for a time corresponding to the gradation data of the digital signal. At this time, by performing high-frequency driving in order to prevent flickering, specifically, a current flows in a short time interval in a range of 60 to 100 Hz, and an overcurrent occurs in the LED lamp. At the time of such high-current driving, the above-mentioned uneven light emission becomes particularly remarkable, and greatly affects the spread of light emission, uneven brightness and the like of the entire display device. As a result, when viewed on the entire display device, the displayed image differs depending on the viewing angle, and while the demand for high brightness and high definition is increasing, such problems cannot be ignored. Have been.

As described above, when the LED chip has uneven light emission, it is difficult to eliminate the unevenness only with the resin lens, and as a result, the LED lamp has uneven light emission. When a display device is formed by arranging a plurality of LED lamps, even if a wide viewing angle is secured by using an elliptical lens, there is uneven light emission.
Display unevenness occurs.

Further, among the above-mentioned display devices, in a large display, the spread of light emission in the vertical direction
For example, when a certain restriction is added, such as suppressing upward light emission, it is necessary to newly design an LED lens and a display device having a directional characteristic satisfying this demand. In addition, uneven light emission in the light emitting element causes variation in luminance when a plurality of LED lamps are arranged.

[0012]

Means for Solving the Problems The present inventors have focused on the fact that the above-mentioned light emission unevenness is made with a certain regularity,
The present invention has been found to work advantageously when providing a unique direction in the spread of light emission, and to solve the above-mentioned problems at the time of high-current operation such as display applications, and have completed the present invention.

That is, the present invention provides the following (1) to
This is achieved by the configuration of (6). (1) In an LED lamp in which a rectangular light emitting chip is molded with an elliptical resin lens as viewed from the light emission observing surface side, the light emitting chip has a pair of positive and negative electrodes including at least a translucent electrode on the same surface side. Wherein the direction connecting the positive and negative electrodes of the light emitting chip is substantially perpendicular to the major axis direction of the ellipse. Thus, even if the light emitting chip has uneven light emission, the LED lamp has a wide viewing angle in the major axis direction of the elliptical resin lens without being affected by the degree of the uneven light emission.

(2) The LED lamp is used for a display device, and the light emitting chip is linearly symmetric with a straight line connecting the electrodes. Thereby, the directivity in the major axis direction of the resin lens can be made excellent in symmetry. At this time, a straight line connecting the electrodes and a straight line (shorter axis) substantially bisected in the longitudinal direction of the ellipse of the resin lens coincide with each other, so that a directional LED lamp having more excellent symmetry is obtained.

(3) The light emitting device according to (1) or (2), wherein the light emitting chip has the pair of positive and negative electrodes arranged at opposing corners of a rectangular chip.
ED lamp. This makes it possible to reduce the area of the region of strong light emission unevenly distributed on the edge portion adjacent to the electrode on the light emitting surface, and as a result, the effect of the unevenly distributed region is small and the LED lamp has a good viewing angle.

(4) The light emitting chip is formed by laminating nitride semiconductors. As a result, even in a nitride semiconductor light-emitting chip having a biased light emission, the light-transmitting electrode serving as a light-emitting surface has excellent directivity.
It becomes an ED lamp.

(5) A display device using the LED lamp, wherein the LED lamp is driven by a high current of 30 mA or more. Even with the use of a light-emitting chip in which light emission becomes uneven due to high-current driving, a display device with a wide viewing angle can be obtained without any special design change.

(6) The LED lamp includes an electrode formed on the exposed nitride semiconductor by removing a part of the stacked nitride semiconductor from the pair of positive and negative electrodes, and It is characterized in that it is arranged below the electrode. This makes it possible to obtain a display device having excellent visibility without using a special design for the display device by utilizing the characteristics of the LED lamp having a directivity deviated in one direction in the direction connecting the electrodes.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, the direction connecting a positive electrode and a negative electrode is a direction of a straight line passing near the center of each electrode, and a direction (D
S). For example, if the shape of the electrode is circular, it is near the center, if it is elliptical, it is near its center of gravity, and in the case of a polygon such as a quadrangle, it is the direction of a straight line passing through the intersection of diagonal lines or near the center of gravity. Preferably, the light is spread in the horizontal direction (the major axis direction of the resin lens) by placing the straight line and the elliptical lens such that the minor axis of the elliptical lens substantially coincides.

The shape of the light-emitting chip is rectangular, for example, rectangular or square. In addition, the shape of the light-emitting chip is not limited to the case where the inner angle is not 90 °, such as a diamond. The preferred shape of the light emitting chip is a straight line passing through each of the above-mentioned electrodes, and the shape of the light emitting chip is line-symmetric (laterally symmetric). This is because, in the present invention, the spread of light emission in the major axis direction of the elliptical resin lens depends on the symmetry with respect to a straight line passing through the electrode, and if the chip is symmetric, the spread in the horizontal direction is good. Become. Specifically, light emitted forward from the light-transmitting electrode depends on the shape of the light-emitting surface, so that the light-emitting surface (the shape of the exposed light-transmitting electrode) is symmetrical with a straight line passing through the electrode. This is preferable because light emission from the front surface also spreads right and left uniformly. In addition to this, by making the straight line passing through the above-mentioned electrodes substantially coincide with the short axis, it is possible to obtain the most preferable spread of light emission in the left-right direction (long-axis direction of the elliptical lens).

Further, the arrangement of the pair of electrodes provided on the light emitting chip directly determines the shape of the light emitting surface described above, and therefore has a great influence on the directivity characteristics of the obtained LED lamp. In the present invention, it is preferable that the electrodes provided on the light emitting chip are arranged at opposing corners of the rectangular chip. This is because when the electrodes are provided at the opposing corners, and as another example provided at the other corners, as shown in FIGS. 1 and 2, the areas of the light-transmitting electrodes are different and the lower layer is exposed. This is due to the difference in the formed edge (length). When each electrode is provided at a corner, a light-emitting surface (exposed translucent electrode) can be made large. Further, since the length of an edge described later is short, a region where light emission is unevenly distributed becomes narrow. This is because, when the current value is changed in the high current region, a change in the intensity distribution of the unevenly distributed light emitting region can be reduced. That is, as the light emitting surface becomes larger and the unevenly distributed light emitting region becomes narrower, the change in the directivity characteristic with respect to the change in the current value decreases, so that a resin lens optically designed for a wide current region can be used. . Explaining with a specific example, comparing the LED lamps shown in FIGS. 1 and 2, for example, the change in the directional characteristic at the time of 60 mA and 100 mA operation is larger in the LED lamp shown in FIG. In addition, it becomes necessary to design a different resin lens depending on the current value, which leads to an increase in cost.

Here, regarding the position of the light emitting chip, in addition to the above-described positional relationship between the light emitting chip and the resin lens in the long axis direction, the position where the light emitting chip is mounted is moved in the short axis direction of the resin lens. This makes it possible to control the directional characteristics in the vertical direction (the short axis direction of the elliptical lens) to some extent, and it is possible to mount the lens at a desired position according to the application. More specifically, the control can be performed within a range of about 10 ° in the vertical directivity. At this time, as the position of the light emitting chip, the ratio of the distance from the long axis to each electrode, in other words, the length of the two line segments obtained when the line connecting the electrodes is divided at the intersection with the long axis, The ratio is
Adjustment in the range of 6: 4 to 4: 6 enables control at the above-mentioned angle. Outside this range, the uniformity of the directional characteristics is lost, the dispersion is severe, and it is not practical.

In the present invention, the light-transmitting electrode is selected in consideration of adhesion to the nitride semiconductor layer and ohmic contact. More specifically, Au, Pt, Ni, Al, W,
In, Cu, Ag, Ir, Pd, Rh, Ti, Co, S
Some of these include n, Pb, and the like, or a material containing a silicide of Pt, W, or Mo, or a metal oxide thereof. When the nitride semiconductor on which the light-transmitting electrode is provided is a p-type, preferably, it is Ru, Rh, Os or Ni / Au (where / indicates a laminated body), Co / Au, Ni / Ti / Au, Cu / A
u, a Pd alloy and a Pt alloy are preferred. Further, the film thickness is preferably in the range of 0.01 to 0.2 μm, because if it is thicker than this range, the translucency tends to deteriorate, and if it is thinner than this range, the contact resistance tends to increase. It is. More preferably, when the angle is 500 ° or less, good translucency can be secured.

In the present invention, the nitride semiconductor is In _x
Al _y Ga _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x +
y ≦ 1), and examples of the n-type nitride semiconductor include undoped (formed without intentionally doping impurities), n-type doped semiconductors, and p-type nitrided semiconductors. As a material semiconductor, a semiconductor to which a p-type impurity is added, and in the formation thereof, thermal annealing and electron beam irradiation for p-type conversion are performed. The active layer is a nitride semiconductor containing In, specifically, InGaN.
In addition, in the present invention, a light emitting chip in which nitride semiconductors are stacked is used. However, the present invention is not limited to this. In the case of a light emitting chip having the above-described electrode arrangement and having similar light emission unevenness, the LED of the present invention is used. It can be used for lamps as well. In that case, the present invention shall be described by replacing the nitride semiconductor in the present specification with a semiconductor, and is widely applied not only to the nitride semiconductor but also to light emitting chips using various semiconductors. It is. That is, the present invention is applied to a light emitting chip using a semiconductor without departing from the technical idea of the present invention.

When a light-transmitting electrode is provided on almost the entire surface of the nitride semiconductor layer, the light-emitting surface has an emission intensity near the edge of the depression as shown by a hatched region 5 'in FIG. High areas are unevenly distributed. In an element structure in which a pair of positive and negative electrodes is provided on the same surface side, a current flows in an in-plane direction inevitably, so that an in-plane distribution of a current flowing in a depth direction occurs. Even if an electrode is provided so as to cover the entire surface in order to suppress this and make the current flow in the plane uniform, this cannot be completely solved. That is, as is clear from the diagram showing the current flow in FIG. 6, even if the light emitting chip is provided with the translucent electrode on almost the entire surface of one semiconductor layer,
In the translucent electrode, a current flows in the in-plane direction A preferentially in the depth direction B, and the flow as indicated by the dotted line B in the drawing decreases, resulting in uneven light emission. Here, the region of strong light emission in the present invention includes the above-mentioned hatched region and light leaking from the etching exposed surface located below (in the depth direction), and includes a region that causes uneven light emission. It is a thing.

As described above, the position or shape of the region having strong light emission tends to depend on the position or shape of the light-transmitting electrode and the exposed surface of the etching, and the present invention is not limited to this. In the present invention, a phenomenon biased to one electrode is used. Although such uneven distribution of the light emitting region occurs even at the time of low current operation, there is no remarkable difference as compared with the case of high current operation. Therefore, even when the long axis direction of the lens and the direction connecting the electrodes are parallel (Comparative Example) and perpendicular, the directional characteristics of the light emission are only slightly different. It didn't matter. For example, the directional characteristics when driven at 30 mA are substantially the same in the horizontal direction as in the case of the vertical direction and as in the case of the parallel direction (shown in FIG. 10B). Also in the vertical direction, as shown in FIGS. 7A and 9A, although there are differences, there are many similarities in their tendency to spread, and these differences are slight in practical use. However, at 60 mA, the horizontal direction (FIG. 8 (1)
1), 10 (b)), in the vertical direction (FIGS. 7 (11), 9).
In (b)), there is a large difference in the directivity characteristics, and this difference becomes remarkable as the current value increases. Therefore, as can be seen from the fact that the directional characteristic diagram has a distorted shape, the LED lamp in the case of the parallel state has a large variation in light emission in operation at high frequency and high current, and is considered to be practically usable. No. Although the parallel case has been described as an example, there is a tendency similar to the parallel case even under conditions that are not included in the vertical case as in the present invention.

As described above, the difference between the obtained LED lamps with respect to the direction in which the electrodes are connected is described. Next, in addition to the condition that the direction in which the electrodes are connected is substantially perpendicular to the long axis direction of the resin lens, positive and negative A description will be given of a change in a display device in which a plurality of LED lamps are arranged by changing the directions of a pair of electrodes. Most of practically used display devices, especially large ones, are installed above the observer 23 as shown in FIG. A viewing angle upward (within the viewing angle of ∠AOC) becomes unnecessary. Therefore, by utilizing the above-described phenomenon in which a region with strong light emission is biased in one of the electrode directions, it is possible to satisfy such a demand for controlling the spread of light emission upward without requiring a special optical design. Can be.

That is, in the LED lamp of the present invention, a state in which the vicinity of the above-mentioned edge formed by removing a part of the nitride semiconductor is directed downward, specifically, the LED lamp is formed on the surface of the exposed lower layer That is, a display device is formed by arranging a plurality of LED lamps in a state in which the electrode is turned below the other electrode. By doing so, the vertical viewing angle in the display device suppresses the upper light emission, and the observer located below the horizontal position where the display device is installed includes the suppressed upper light emission. Thus, information is provided with a good spread of light emission. From the above, it is most preferable that the direction connecting the electrodes is parallel to the vertical direction of the display device, and the electrode provided in the exposed lower layer is disposed below the other electrode. Needless to say, Specifically, as shown in FIG. 11, there is a display device 21 disposed above the observer 23, and a viewing angle in a direction perpendicular to the ground, which is closer to the observation side than the horizontal position AO, in a viewing angle perpendicular to the ground. In order to make the viewing angle of ∠AOB effective, and to make the viewing angle of ∠AOC above almost ineffective, as shown in the partially enlarged view of FIG. It is arranged below one electrode 1. That is, the LED chip 1
At 0, the side having the higher emission intensity in the direction connecting the electrodes (in this case, the electrode 6 side) is disposed below as shown in FIG.

Here, the high current value in the present invention is 30 mA or more, specifically, in the range of 60 to 100 mA, which is not preferable because the load on the element is large.
Operation of 00 mA or more is also possible. In addition, in order to form a pair of positive and negative electrodes on the same surface, a part of the surface of the uppermost layer of the normally stacked nitride semiconductor is removed to expose the lower layer. At this time, when an electrode is provided on the same surface side, as a method for exposing the lower nitride semiconductor layer, there are methods such as wet etching and dry etching. To form a smooth surface, preferably dry etching is used. Is used. The dry etching includes, for example, reactive ion etching (RIE) and reactive ion beam etching (RIB).
E), an electron cyclotron etching (ECR), an ion beam etching, and the like, all of which can remove a part of the nitride semiconductor by etching by appropriately selecting an etching gas. For example, a specific nitride semiconductor etching means described in Japanese Patent Application Laid-Open No. H8-17803 previously filed by the present applicant can be used.

The leads on which the chips are arranged can be provided with an LED chip as a light emitting element and have a function as a reflector. In order to improve the reflection function, it is preferable to make the tip of the lead into a cup shape, and the size may be sufficient as long as the LED chip can be mounted on a device such as a die bond. Also, the shape of the cup,
Various shapes such as a track shape, an elliptical shape, and a rectangular shape can be selected from the light emission observation surface side. As shown in FIG. 3, a track shape or an oblateness (short axis length / long axis length) is selected. A high (long shape extending in the long axis direction) elliptical cup. When the cup is arranged so that the longitudinal direction of the cup substantially coincides with the long axis direction of the resin lens, a wide viewing angle in the horizontal (long axis of the resin lens) direction Is preferable because it can be secured.

In the present invention, the shape of the resin lens is elliptical, as shown in FIGS. 1 to 4 and the like, as long as it is elliptical as viewed from the emission observation surface side. An LED lamp having a wide viewing angle in the major axis direction (longitudinal direction) of a resin lens using a shape, a rectangle with rounded corners, or a track. (Operation / Effect) The LED lamp of the present invention uses an elliptical lens and has a wide viewing angle in the major axis direction (longitudinal direction), and the arrangement of the light emitting chips used therein is carefully adjusted. Without special resin lens design,
Further, it is possible to easily control the directivity characteristics regardless of a change in driving conditions. The light emitting chip has a pair of positive and negative electrodes including a translucent electrode on the same surface side, and the direction connecting the electrodes is substantially perpendicular to the long axis direction of the resin lens, so that the light emitting chip is excellent even in the wide viewing angle. Light emission can be easily performed. This is because the directional characteristics of the light emitting chip, which variously change depending on the driving conditions, are mainly due to the electrode arrangement. Therefore, when the intersection between the direction connecting the electrodes and the long axis direction of the resin lens is not perpendicular, the LED is turned off. This is because the lamp is greatly affected by the change in its directivity.

At this time, it is preferable that the electrode arrangement is such that the light emitting chip is linearly symmetrical with a straight line connecting the electrodes, and more specifically, the light emitting surface is line symmetrical, so that the resin lens The LED lamp has a more preferable spread of light emission in the major axis direction. By using the LED lamp of such a light emitting chip, it is possible to suppress the variation of the light emission unevenness of each chip from being reflected in the LED lamp, and the same applies to the case where a chip having a different light emission unevenness is used. The resulting LED lamp has a long-axis direction directivity.

Further, since the unevenness of light emission of such a light emitting chip tends to be strong at the time of high current operation, the viewing angle in the short axis direction of the resin lens is reduced when utilizing it for a display device. A controlled LED lamp can be achieved without special design changes. Specifically, the region where the light emission is strong in the light emitting chip is disposed so as to be located on one side of the long axis of the resin lens, whereby the one side is biased to one side in the short axis direction of the resin lens. When the LED lamp is used for a display device, the direction in which this bias is present is taken in the vertical direction, and the region where light emission is strong is directed to the light emission observer side. By doing so, a display device having a desired viewing angle can be easily realized without special design on the display device side.

Hereinafter, embodiments of the present invention will be described. Needless to say, a structure in which a light-transmitting electrode is formed in an n-type layer and a lower layer exposed by etching or the like is used as a p-type layer may be employed. Absent.

[0035]

Embodiment 1 As shown in FIGS. 5 and 6, each layer of a nitride semiconductor is laminated, a mask is formed on the surface of a p-type nitride semiconductor layer 9, and reactive ion etching (RIE) is performed.
The apparatus is selectively etched from the uppermost p-type nitride semiconductor layer 9 to expose the surface of the n-type nitride semiconductor layer 7 where the negative electrode 6 is to be formed. Then, after removing the mask,
A light-emitting element having a translucent electrode made of Ni / Au formed on the surface of a p-type layer 9 and a positive electrode (p-side pad electrode) 1 for bonding formed thereon, as shown in FIG. It is mounted on the center of the reflection mirror of the lead frame having the reflection mirror. This chip has a structure in which a resin is molded as an elliptical lens, and each electrode is electrically connected to a lead frame by a gold wire 4. At the time of low current operation (30 mA), the obtained LED lamp has a horizontal directional characteristic (see FIG.
(A)) is similarly good, and although it is inferior to the left-right symmetry in the characteristic diagram in the vertical direction, it is sufficient for practical use.

As shown in FIG. 5, high current operation (60 m
In A), a region 5 'having a high luminous intensity is unevenly distributed from the vicinity of the edge of the recessed portion of the light emitting chip at a certain width. For this reason, the directivity changes remarkably in FIG.
Light emission to the negative electrode side increases.

As described above, when the obtained LED lamp is made to emit light at a high current (60 mA), the LED lamp shown in FIGS.
As can be seen from (11), a wide viewing angle is maintained in the horizontal direction, and although the light is biased toward one side in the vertical direction, uniform spread of light emission is realized, and light emission at 100 mA has the same tendency. Had been maintained. For this reason, it can be used more favorably at the time of high current operation than the conventional one. When a plurality of the obtained LED lamps were arranged and used for a display driven at a high frequency, the spread of light emission in the horizontal direction was good. In the vertical direction, as shown in FIG. 11, a display, which is the display device 21, is installed above the observer 23, and the LED constituting the display device has the negative electrode placed below the positive electrode with respect to the vertical direction of the ground. By arranging them, it is possible to observe good light emission without variation from any angle below (水平 AOB) below the horizontal position of the display, and to observe light emission above the horizontal position (∠AOB).
Light emission to OC) was successfully eliminated.

Embodiment 2 FIG. 2 relates to another embodiment of the present invention and is a schematic plan view seen from the light emission observation surface side. The light emitting chip used for this LED lamp is
As shown in the figure, the positions of the electrodes are different from those of the first embodiment, and the positive electrode 1 and the negative electrode 9 are located near the middle point with respect to a pair of opposing sides of the light emitting chip. The n-type layer is formed on the exposed surface by removing the layer, the active layer and the like by etching. The same translucent electrode as in Example 1 was used.

Even with such an electrode arrangement, Embodiment 1
In the same manner as described above, a region with strong light emission is formed with a certain width from the vicinity of the exposed edge of the recess of the negative electrode. The directional characteristics of light emission during the high current (100 mA) operation are shown in FIG.
As shown in (12) and 8 (12), in the vertical direction (the short axis direction of the resin lens), the angle is deviated to one side, and is slightly wider than that of the first embodiment.
A similar tendency is observed during the operation, but the change in the directivity with respect to the change in the current value is larger than that in the first embodiment. Further, as in the case of Example 1, the state of the light emission was observed using a display used under a high current.
Even if it was installed at a further higher position, light emission was favorable.

[Embodiment 3] FIG. 3 is a schematic plan view of another embodiment of the present invention viewed from the light emission observation surface side. The light emitting chip used for this LED lamp is
As the translucent electrode, Pd of 50 °, Pt of 80 °, and Au of 100 ° are sequentially laminated and annealed at 500 ° C., and the cup has a track-like shape as shown in FIG. An LED lamp was manufactured in the same manner as in Example 1 except that the major axis of the cup substantially coincided with the longitudinal direction of the cup.

The obtained LED lamp has almost the same directional characteristics in the vertical direction as in the first embodiment, but the viewing angle in the horizontal direction is significantly larger than that in the first embodiment, as is clear from FIG. Was wide. For this reason, when used for a display, excellent light emission can be observed even at a wider angle with respect to the horizontal direction than in the first and second embodiments. Further, the light emitting chip has uneven light emission near the edge of the etching on the negative electrode side at the time of high current operation, and is substantially equivalent to that of the first and second embodiments. The display device consisting of the LED with the negative electrode of
Compared with Examples 1 and 2, it has a similar downward viewing angle,
In addition, the horizontal direction has a wider viewing angle.

[Embodiment 4] The light emitting chip for the resin lens is moved by 10% to the positive electrode side in the direction connecting the electrodes, that is, the point where the line connecting the electrodes intersects the long axis of the resin lens is the positive electrode. Side: negative electrode side = 6: 4, and an LED lamp was obtained in the same manner as in Example 1 except that the resin lens was placed so that the short axis of the resin lens coincided with the line segment.

At the time of high current operation of the obtained LED lamp (6
0 mA) in the vertical direction is shown in FIG.
4), 8 (14). As is clear from this, in the vertical direction (the major axis direction of the resin lens), the spread from the horizontal position to the upper side is better than in the first embodiment. If this is used for a display, for example, light emission from the display can be favorably observed compared to that of the first embodiment even if the installation of the display to the observer is reduced. Further, the directional characteristics in the horizontal direction showed a good viewing angle as in the first and second embodiments.

[Comparative Example] As a comparative example, an elliptical resin lens was prepared in which the direction connecting the electrodes was parallel to the major axis direction. When such an LED lamp, that is, the light emitting chip of FIG. 1 (Example 1) is rotated by 90 °, the directional characteristic in the vertical direction is 30 mA as shown in FIG.
At the time of operation, the right and left sides are approximately uniform, and at the time of high current operation (60, 100 mA), the uniformity tends to be collapsed, so that an irregular shape is exhibited. Also, in the horizontal direction, as shown in FIG.
A) had good directivity characteristics, but the symmetry was broken at the time of high current operation (60 mA), and at the time of 100 mA operation, the tendency was remarkable and became uneven in the horizontal direction. When used, the brightness varies.

[0045]

According to the present invention, an LED having a positive electrode and a negative electrode on the same surface side and provided with a translucent electrode, in particular, an LED using a nitride semiconductor
Although the lamp has uneven light emission, operation at a relatively low current has no problem in its directional characteristics. However, as the driving conditions of the LED become strict, the unevenness of light emission became remarkable, and the influence of the unevenness on the directivity was not negligible. The LED lamp of the present invention shows good characteristics for a specific viewing angle while securing sufficient directional characteristics in the horizontal direction. The LED lamp of the present invention is specially optically designed to have a wide viewing angle in the horizontal direction and a good viewing angle in the horizontal direction from the horizontal direction to the lower direction in the vertical direction by using the LED lamp of the present invention for such a directional characteristic, for example, in a display or the like. It can be provided without the need for a lens or the like. As described above, the LED lamp of the present invention can be preferably used not only for the display device but also for applications in which light emission is suppressed in at least one of the up, down, left, and right directions.

[Brief description of the drawings]

FIG. 1 is a schematic plan view according to one embodiment of the present invention.

FIG. 2 is a schematic plan view according to one embodiment of the present invention.

FIG. 3 is a schematic plan view according to one embodiment of the present invention.

FIG. 4 is a schematic plan view of a conventional LED lamp.

FIG. 5 is a perspective view illustrating light emission unevenness.

FIG. 6 is a schematic cross-sectional view illustrating a flow of current in a light emitting chip.

FIG. 7 is a directional characteristic diagram in the vertical direction (the short axis direction of the resin lens) of each embodiment of the present invention.

FIG. 8 is a directional characteristic diagram in a horizontal direction (long axis direction of a resin lens) of each embodiment of the present invention.

FIG. 9 is a directional characteristic diagram in a vertical direction (a short axis direction of a resin lens) of a comparative example.

FIG. 10 is a horizontal direction (long axis direction of a resin lens) of a comparative example.
Directivity characteristic diagram.

FIG. 11 is a schematic plan view illustrating one embodiment of the present invention.

[Explanation of symbols]

 1, positive electrode (pad electrode) 2, resin lens 3, 3 ', lead frame 4, 4', gold wire 5, 5 ', translucent electrode 6, negative electrode 7, n-type nitride semiconductor layer 8, active layer 9, p-type nitride semiconductor layer

Claims (6)

[Claims] 1. An LED lamp in which a rectangular light emitting chip is molded with an elliptical resin lens as viewed from a light emission observing surface side, wherein the light emitting chip includes a pair of positive and negative electrodes including at least a translucent electrode on the same surface side. Having an electrode,
The direction connecting the positive and negative electrodes of the light emitting chip is substantially perpendicular to the major axis direction of the ellipse.
D lamp. 2. The LED lamp according to claim 1, wherein said LED lamp is used for a display device, and said light emitting chip is line-symmetric with a straight line connecting said electrodes. 3. The LED lamp according to claim 1, wherein said light emitting chip comprises said pair of positive and negative electrodes arranged at opposing corners of a rectangular chip. 4. The LED lamp according to claim 1, wherein said light emitting chip is formed by laminating a nitride semiconductor. 5. A display device using the LED lamp, wherein the LED lamp is driven by a high current of 30 mA or more. 6. An LED lamp comprising: an electrode formed on a nitride semiconductor exposed by removing a part of the stacked nitride semiconductor from the pair of positive and negative electrodes; The display device according to claim 5, wherein the display device is disposed so as to be lower than the display device.