Light emitting apparatus using semiconductor light-emitting device

A light emitting apparatus includes a plurality of wiring electrodes, a plurality of semiconductor light emitting devices connected between two of the plurality of wiring electrodes, and a reflection layer of metal disposed under the plurality of semiconductor light emitting devices, wherein the plurality of wiring electrodes are connected in series with each other by the plurality of semiconductor light emitting devices, and at least one of the plurality of semiconductor light emitting devices is connected between two consecutive wiring electrodes among the plurality of wiring electrodes.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2019/014352, filed on Oct. 29, 2019, which claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0169630, filed on Dec. 26, 2018 in the Republic of Korea, the contents of all these applications being hereby incorporated by reference into the present application.

TECHNICAL FIELD

The present invention relates to a lamp using a semiconductor light emitting device.

BACKGROUND ART

Lamps that emit light are being used in various fields. For example, a vehicle is provided with various vehicle lamps having a lighting function or a signal function. Referring toFIG.1, in general, the vehicle1has a lamp device100for stably securing the driver's visibility when the ambient illuminance is low during driving or for notifying other vehicles of the driving state of the vehicle1.

The vehicle lamp device includes a head lamp installed at the front of the vehicle and a rear lamp installed at the rear of the vehicle. A headlamp is a lamp that illuminates the front and illuminates the front during night driving. The rear lamp includes a brake light that is turned on when a driver operates a brake, and a direction indicator light indicating a moving direction of the vehicle.

In general, a halogen lamp or a gas discharge lamp has been mainly used, but recently, a light emitting diode (LED) is attracting attention as a light source of a vehicle lamp.

The light emitting diode not only increases the design freedom of the lamp by minimizing its size, but also has economic efficiency due to its semi-permanent lifespan. However, most are currently being produced in the form of a package. A light emitting diode (LED) itself, not a package, is a semiconductor light emitting device that converts current into light, and is being developed as a light source for display images of electronic devices including information and communication devices.

Meanwhile, a lamp using a semiconductor light emitting device may include a reflection layer made of a metal material provided on a surface opposite to the light emitting direction of the semiconductor light emitting device. When power is supplied to the electrode lines disposed on the wiring board of the lamp, a voltage due to leakage current may be applied between the electrode lines and the reflection layer.

For example, in a high-temperature and high-humidity environment, the applied voltage may increase due to the leakage current, and in this case, there is a risk that lighting failure of the semiconductor light emitting device may occur.

Also, the voltages of the electrode lines may be different from each other, and accordingly, the voltage applied to the reflection layer by the leakage current may be different for each region. As a result, the reflection layer may be damaged, such as the metal of the reflection layer is peeled off. As a result, there is a possibility that the reliability of the lamp may be deteriorated due to the above problems.

DISCLOSURE

Technical Problem

An object of the present invention is to provide a lamp using a semiconductor light emitting device capable of preventing a decrease in reliability due to leakage current between an electrode line and a reflection layer.

Technical Solution

A lamp according to an embodiment of the present invention may include a wiring board, a plurality of wiring electrodes disposed on the wiring board, a plurality of semiconductor light emitting devices connected between two wiring electrodes among the plurality of wiring electrodes, and a reflection layer of a metal material disposed under the wiring board, wherein the plurality of wiring electrodes are connected in series with each other by the plurality of semiconductor light emitting devices, and at least one of the plurality of semiconductor light emitting devices can be connected between two consecutive wiring electrodes among the plurality of wiring electrodes.

According to an embodiment, the plurality of semiconductor light emitting devices may be divided into at least one group, and at least one semiconductor light emitting device included in the same group may be connected in parallel between the same two wiring electrodes.

According to an embodiment, the reflection layer may be provided with a power connection part for supplying power to the reflection layer. When power is supplied to the plurality of wiring electrodes and the plurality of semiconductor light emitting devices, power may be supplied to the reflection layer through the power connection part.

A voltage applied to the reflection layer may be greater than or equal to a highest voltage among voltages applied to the plurality of wiring electrodes.

According to an embodiment, the power connection part may have a form in which a portion of the reflection layer is extended, or a form in which a metal of the same material as the reflection layer is connected to the reflection layer.

In some embodiments, the reflection layer may include a plurality of partial reflection layers spaced apart from each other in a horizontal direction.

According to an embodiment, the plurality of semiconductor light emitting devices can be divided into a plurality of groups, and at least one semiconductor light emitting device included in the same group is connected in parallel between the same two wiring electrodes, and the number of the plurality of partial reflective layers is equal to the number of the plurality of groups.

Each of the plurality of partial reflection layers may be disposed to correspond to one different group.

In some embodiments, the number of the plurality of partial reflection layers may be the same as the number of the plurality of semiconductor light emitting devices. Each of the plurality of partial reflection layers may be disposed to correspond to any one semiconductor light emitting device that is different from each other.

The lamp may further include a plurality of transparent electrodes connected between the plurality of wiring electrodes and the plurality of semiconductor light emitting devices.

The lamp may further include an insulating layer disposed between the wiring board and the reflection layer.

Advantageous Effects

According to an embodiment of the present invention, the lamp can be connected to a power source to the reflection layer to apply a predetermined voltage, thereby minimizing metal peeling of the wiring electrodes and preventing deterioration of the reliability of the lamp.

According to an embodiment of the present invention, the reflection layer provided in the light source unit of the lamp may be divided into a plurality of partial reflection layers so that different voltages are applied. Accordingly, the deviation between the voltage of each of the plurality of partial reflection layers and the voltage of the wiring electrodes corresponding to each of the plurality of partial reflection layers is reduced, thereby effectively reducing the electrochemical reaction and improving the reliability of the lamp.

MODE FOR INVENTION

Hereinafter, the embodiments disclosed in the present specification will be described in detail with reference to the accompanying drawings, but the same or similar elements are assigned the same reference numerals regardless of reference numerals, and redundant description thereof will be omitted. The suffixes “module” and “part” for the elements used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have distinct meanings or roles by themselves.

In addition, in describing the embodiments disclosed in the present specification, if it is determined that detailed descriptions of related art technologies may obscure the meaning of the embodiments disclosed in this specification, the detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical spirit disclosed in the present specification by the accompanying drawings.

It is also understood that when an element, such as a layer, region, or substrate, is referred to as being “on” another element, it may be directly on the other element or intervening elements therebetween.

On the other hand, the lamp described in the present specification may be applied to a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a PDA (personal digital assistants), a PMP (portable multimedia player), a navigation, a slate PC, a Tablet PC, an Ultra Book, a digital TV, a desktop computer, and the like. However, those skilled in the art will readily appreciate that the configuration according to the embodiment described in the present specification may be applied to a lamp, even if it is a new product form to be developed later.

Meanwhile, the lamp described in this specification may be utilized for a vehicle. The vehicle lamp may include a headlamp, a tail lamp, a side lamp, a fog lamp, a turn signal lamp, a brake lamp, an emergency lamp, and a reversing lamp and the like.

FIG.2is a cross-sectional view of a lamp device included in a vehicle.

A vehicle lamp10according to an embodiment of the present invention may include a frame11fixed to a vehicle body and a light source unit12installed on the frame11.

A wiring line for supplying power to the light source unit12may be connected to the frame11, and the frame11may be directly fastened to the vehicle body or fixed through a bracket. As illustrated, a lens unit may be provided in order to more diffuse and sharpen the light emitted by the light source unit12.

The light source unit12may be a flexible light source unit that can be bent, crooked, twisted, folded, or rolled by an external force.

In a state in which the light source unit12is not bent (eg, a state having an infinite radius of curvature, hereinafter referred to as a first state), the light source unit12may be flat. In a state bent by an external force in the first state (for example, a state having a finite radius of curvature, hereinafter referred to as a second state), the flexible light source unit may have a curved surface at least partially curved or curved.

The pixel of the light source unit12may be implemented by a semiconductor light emitting device. In the present invention, a light emitting diode (LED) is exemplified as a type of a semiconductor light emitting device that converts current into light. The light emitting diode is formed in a small size, so that it can serve as a pixel even in the second state.

Meanwhile, the light source unit12according to the present invention may include a unit light source, a base substrate, and a connection electrode. Hereinafter, the above-described elements will be described in detail.

The light source unit12may be comprised of only the unit light source. Hereinafter, the unit light source will be described in detail through the light source unit12made of only the unit light source.

FIG.3is a plan view of region A ofFIG.2,FIG.4is a conceptual diagram illustrating a flip chip semiconductor light emitting device,FIG.5is an enlarged view of region B ofFIG.3, andFIG.6is a cross-section taken view taken along line V-V ofFIG.3.

As shown, the light source unit12may include a wiring board100, a plurality of electrode lines110and120, a transparent electrode130, and a semiconductor light emitting device150. Hereinafter, the above-described elements will be described in detail.

Referring toFIG.3, a plurality of electrode lines may be disposed on the wiring board. Each of the electrode lines110and120may protrude from the bus electrodes110′ and120′ and extend in one direction to form a bar shape. Meanwhile, each of the electrode lines110and120has one end formed opposite to the bus electrode.

When each of the electrode lines110and120is described in the form of a bar having both ends, one end of the electrode line is connected to the bus electrode, and the other end is disposed opposite the bus electrode. Meanwhile, in the present specification, an intermediate point between the two ends is referred to as a central portion of the electrode line.

Meanwhile, two types of bus electrodes110′ and120′ may be disposed on the wiring board. Specifically, a voltage applied between the two bus electrodes110′ and120′ is applied to each of the semiconductor light emitting devices150. Through this, each of the semiconductor light emitting devices150emits light. The electrode lines110and120extending from each of the two bus electrodes110′ and120′ can be electrically connected to the semiconductor light emitting devices150such that the voltage applied between the two bus electrodes110′ and120′ may be applied to each of the semiconductor light emitting devices150.

At this time, the individual semiconductor light emitting device150should be electrically connected to each of the two types of electrode lines110′ and120′. Before describing the structure in which the semiconductor light emitting device150is electrically connected to the electrode lines, the structure of the semiconductor light emitting device150will be firstly described.

Referring toFIG.4, the semiconductor light emitting device150may be a flip chip type light emitting device.

For example, the semiconductor light emitting device may include a p-type electrode156, a p-type semiconductor layer155on which the p-type electrode156is formed, an active layer154disposed on the p-type semiconductor layer155, an n-type semiconductor layer153disposed on the active layer154, and an n-type electrode152spaced apart from the p-type electrode156in the horizontal direction on the n-type semiconductor layer153. In this case, the p-type electrode156may be electrically connected to the electrode line110extending from either of the two bus electrodes, and the n-type electrode152may be connected to an electrode line120extending from the other one of the two bus electrodes.

Referring toFIG.6, in the lamp according to the present invention, the p-type electrode and the n-type electrode are disposed in the direction of the light emitting surface. That is, the light emitted from the lamp according to the present invention is emitted to the outside through the p-type electrode and the n-type electrode. Due to these structural features, in order to increase the amount of light of the lamp, the structure overlapping the semiconductor light emitting device should be minimized.

Meanwhile, the reflection layer160may be disposed on the opposite side of the light emitting surface of the semiconductor light emitting device to maximize the amount of light of the lamp. The reflection layer reflects light emitted from the semiconductor light emitting device and directed toward the lower side of the lamp to increase the amount of light of the lamp. Meanwhile, the reflection layer160may be disposed on the base substrate170.

On the other hand, when the electrode line made of metal or alloy is directly electrically connected to the semiconductor light emitting device, the amount of light of the lamp may be reduced because the electrode line covers the light emitting surface of the semiconductor light emitting device. To prevent this, referring toFIGS.5and6, each of the electrode lines110and120is electrically connected to the semiconductor light emitting device through the transparent electrode130.

The transparent electrode130may be made of a material having high light transmittance and conductivity. For example, the transparent electrode130may be ITO. The transparent electrode130has very high light transmittance than the electrode line, but has a little poor electrical conductivity. As shown inFIG.6, when the semiconductor light emitting device150overlaps the transparent electrode, a decrease in the amount of light from the lamp can be minimized.

The lamp according to the present invention may include a power supply for applying a current to the semiconductor light emitting devices150. The power supply unit applies a current to the bus electrode, and the applied current flows to the semiconductor light emitting devices along a plurality of electrode lines. However, when the power supply unit applies a current to one end of the bus electrode, the amount of current flowing through each of the electrode lines arranged in a row is different from each other. This is due to the voltage drop across each of the electrode lines. For this reason, voltage non-uniformity as shown inFIG.7can be generated.

FIG.7is a graph showing the magnitude of a voltage applied to a semiconductor light emitting device according to a distance between a bus electrode and a semiconductor light emitting device in the lamp described inFIG.3.

As shown in the figure, as the semiconductor light emitting device moves away from the bus electrode, it gradually decreases and then increases again. That is, the voltage applied to the semiconductor light emitting device adjacent to the central portion of the electrode line is smaller than the voltage applied to the semiconductor light emitting device adjacent to both ends of the electrode line. Accordingly, the amount of light emitted from the semiconductor light emitting device varies depending on the position of the semiconductor light emitting device. As the area of the lamp increases, the difference in the amount of light becomes more evident.

The present invention proposes a structure for solving the problem that the amount of light of a semiconductor light emitting device varies depending on the position of the semiconductor light emitting device due to a voltage drop. The lamp according to the present invention may include all of the elements described with reference toFIGS.3to6.

FIG.8is a conceptual diagram illustrating an embodiment of the lamp according to the present invention, andFIG.9is a graph illustrating the voltage drop prevention effect of the lamp according to the present invention.

Although the above-described transparent electrode is not illustrated inFIG.8, as described inFIG.5, the electrode line can be electrically connected to the semiconductor light emitting device through the transparent electrode. Hereinafter, all of the drawings to be described are illustrated by omitting the transparent electrode, but all electrode lines can be electrically connected to the semiconductor light emitting device through the transparent electrode.

A lamp according to the present invention may include a wiring board, a bus electrode, a plurality of electrode lines, a plurality of semiconductor light emitting devices, a plurality of transparent electrodes, and a current injection unit. The wiring board, the plurality of light emitting devices, and the plurality of transparent electrodes are replaced with descriptions ofFIGS.1to7.

In the present invention, a current injection part210acan be separately used instead of applying a current to the wiring electrode220adirectly from the power supply unit. Referring toFIG.8, the current injection part210acan be formed to extend along one direction in which the bus electrode220aextends, and is disposed parallel to the bus electrode220a.

The current injection part210acan be electrically connected to the bus electrode220a. For this purpose, the present invention can include a plurality of connection electrodes280. The connection electrodes280can be disposed between the bus electrode220aand the current injection part210a. The plurality of connection electrodes280can be disposed to be spaced apart from each other by a predetermined distance along one direction in which the bus electrode220aextends. A current applied from the power supply can be applied to the bus electrode220aalong each of the plurality of connection electrodes280.

Meanwhile, the resistance values of each of the connection electrodes280may be different from each other. Specifically, the resistance value of each of the connection electrodes280may decrease as the distance from the power supply increases. This is to compensate for the voltage drop that occurs as the distance from the power supply is increased. Through this, according to the present invention, the same current can be applied to each of all the electrode lines221aextending from the wiring electrode220a.

When the currents applied to each of the electrode lines221aare the same, the voltages applied to each of the semiconductor light emitting devices250become the same as shown inFIG.9. Through this, according to the present invention, the same amount of light can be emitted regardless of the position where the semiconductor light emitting device250is disposed. Also shown inFIG.8, for example, are electrode lines221b, a wiring electrode220b, and a current extraction part210b.

Meanwhile, the present invention provides various modified embodiments for sequentially changing the resistance value of the connection electrode.

FIG.10is a conceptual diagram illustrating a modified embodiment of a connection electrode provided in a lamp according to the present invention.

Referring toFIG.10, the connection electrode280′ according to the present invention may include a first connection part connected to a current injection part210a, a resistor part extending from one end of the first connection part along the one direction, and a second connection part extending from one end of the resistor part and connected to the wiring electrode.

The present invention can change the shape of the resistor part to change the resistance value of the connection electrode. In an embodiment, the length L of the resistor part provided in each of the connection electrodes280′ may be different from each other. In detail, the length of the resistor part provided in each of the connection electrodes280′ may be shorter as the distance from the power supply increases. As the length of the resistance portion decreases, the resistance value of the connection electrode280′ decreases. According to the above-described structure, the connection electrode having a lower resistance value is disposed as the distance from the power supply unit increases.

In another embodiment, the width of the resistor part may become thinner as it moves away from the power supply. As the width of the resistance portion decreases, the resistance value of the connection electrode280′ decreases. According to the above-described structure, the connection electrode having a lower resistance value is disposed as the distance from the power supply unit increases.

As described above, in the present invention, the resistance values of the connection electrodes are variously adjusted by utilizing the space between the wiring electrode and the current injection unit. Through this, according to the present invention, it is possible to minimize the area of the non-emission area of the lamp and increase the light uniformity of the lamp.

On the other hand, the present invention can improve the light uniformity of the lamp by crossing the wiring connected to the semiconductor light emitting device.

FIG.11is a conceptual diagram illustrating the presence or absence of a voltage drop according to the structure of a bus electrode, andFIG.12is a conceptual diagram illustrating a modified embodiment according to the present invention.

The wiring electrode provided in the lamp according to the present invention may include a first wiring electrode arranged in parallel with the current injection unit and a second wiring electrode arranged to be spaced apart from the first wiring electrode by a predetermined distance.

Here, the first wiring electrode corresponds to the wiring electrode110shown in the upper part ofFIG.4, and the second wiring electrode corresponds to the wiring electrode120shown in the center part ofFIG.4. All regions of the second wiring electrode should be formed as equipotential surfaces, but referring toFIG.11(a), a voltage drop occurs between V1and V2. This adversely affects the light uniformity of the lamp.

To prevent this, in the present invention, as shown inFIG.11(b), the electrode line extends in both directions at the same point of the wiring electrode. In this case, an electrode extending in the first direction is used as a cathode, and an electrode extending in a second direction opposite to the first direction is used as an anode. To this end, the semiconductor light emitting device disposed on the upper side and the semiconductor light emitting device disposed below the wiring electrode are disposed in a state inverted by 180 degrees from each other.

Specifically, the p-type electrode of the semiconductor light emitting device disposed above the wiring electrode ofFIG.11(b)can be electrically connected to the electrode line disposed on the left side of the semiconductor light emitting device. In contrast, the p-type electrode of the semiconductor light emitting device disposed below the wiring electrode ofFIG.11(b)can be electrically connected to the electrode line disposed on the right side of the semiconductor light emitting device.

When the structure ofFIG.11(b)is applied to the entire lamp, it has the same structure as that ofFIG.12. As shown, the first wiring electrode220acan be electrically connected to the current injection part210a, and two types of electrode lines can be disposed on the second bus electrode240. Specifically, a first electrode line extending241in a first direction and a second electrode line241extending in a second direction opposite to the first direction are disposed on the second bus electrode240. Here, the second electrode line is formed extending from the same point as the point where the first electrode line is formed.

The first and second electrode lines can be formed to extend in both directions from one point of the second bus electrode240. A p-type electrode of the semiconductor light emitting device can be connected to one of the first and second electrode lines, and an n-type electrode can be connected to the other. Through this, it is possible to prevent a voltage deviation from occurring in the second wiring electrode240.

As described above, according to the present invention, since a uniform voltage is applied to the semiconductor light emitting devices provided in the lamp, each of the semiconductor light emitting devices provided in the lamp can emit light with the same brightness.

FIG.13is a conceptual diagram illustrating a lamp having a series-parallel connection structure according to an embodiment of the present invention.

Although the transparent electrode described above is not shown inFIG.13, as described inFIG.5, the electrode line (wiring electrode) can be electrically connected to the semiconductor light emitting device through the transparent electrode.

A lamp according to an embodiment of the present invention may include a light source unit including a wiring board, a plurality of wiring electrodes, a plurality of semiconductor light emitting devices, a plurality of transparent electrodes, a reflection layer, and the like. The wiring board, the plurality of semiconductor light emitting devices, and the plurality of transparent electrodes are replaced with the description ofFIGS.1to7.

Meanwhile, althoughFIG.13illustrates the light source unit300including a unit light source, according to an embodiment, the light source unit300may include a plurality of unit light sources arranged in an array form.

Referring toFIG.13, the light source unit300may include a plurality of wiring electrodes310,320,330,340, and350, and a plurality of semiconductor light emitting devices360connected between two of the plurality of wiring electrodes.

Similar to that described above inFIG.3, each of the plurality of wiring electrodes310to350may include a bus electrode and electrode lines protruding from the bus electrode and extending in one direction to form a bar shape. Each of the bus electrodes may be parallel to each other. The electrode lines may be electrically connected to the semiconductor light emitting devices360.

Meanwhile, the plurality of semiconductor light emitting devices360may be connected in series and parallel form through the plurality of wiring electrodes310to350. In other words, the plurality of wiring electrodes310to350may be serially connected to each other through the plurality of semiconductor light emitting devices360and transparent electrodes.

As shown inFIG.13, semiconductor light emitting devices included in the first group370aamong the plurality of semiconductor light emitting devices360may be connected between the first wiring electrode310and the second wiring electrode320. The semiconductor light emitting devices included in the second group370bmay be connected between the second wiring electrode320and the third wiring electrode330, and the semiconductor light emitting devices included in the third group370cmay be connected between the third wiring electrodes330and the fourth wiring electrode340. And the semiconductor light emitting devices included in the fourth group370dmay be connected between the fourth wiring electrode340and the fifth wiring electrode350.

That is, it can be seen that the semiconductor light emitting devices included in the same group are connected in parallel between the same wiring electrodes. Also, it can be seen that each of the groups370ato370dis connected in series through the wiring electrodes310to350. Accordingly, the plurality of semiconductor light emitting devices360included in the light source unit300may be connected according to a series-parallel connection structure. Accordingly, the uniformity of light emitted from the plurality of semiconductor light emitting devices360provided in the light source unit300may be secured.

When the light source unit300is driven, current may be supplied to the first wiring electrode310among the plurality of wiring electrodes310to350. For example, a first voltage V1can be applied to the first wiring electrode310to supply current, and a fifth voltage V5lower than the first voltage V1can be applied to the fifth wiring electrode350. The fifth voltage V5may be 0V, but is not limited thereto.

As the first voltage V1is applied to the first wiring electrode310and the fifth voltage V5is applied to the fifth wiring electrode350, current flows from the first wiring electrode310to the fifth wiring electrode350. In this case, assuming that the characteristics of the plurality of semiconductor light emitting devices360are identical to each other, the magnitude of the voltage dropped between the respective wiring electrodes may be substantially the same.

Accordingly, the second voltage V2which is lowered from the first voltage V1, can be applied to the second wiring electrode320, a third voltage V3which is a voltage of the predetermined magnitude has been dropped from the second voltage V2can be applied to the third wiring electrode330. A fourth voltage V4in which the voltage of the predetermined magnitude is lowered from the third voltage V3may be applied to the fourth wiring electrode340. In addition, the fifth voltage V5may be smaller than the fourth voltage V4by the predetermined level.

FIG.14is a perspective view illustrating wiring electrodes, semiconductor light emitting devices, and a reflection layer of the lamp shown inFIG.13.

Referring toFIG.14, as described above with reference toFIG.6, a reflection layer380may be provided under the wiring board on which the wiring electrodes310to350and the plurality of semiconductor light emitting devices360are formed.

Also, although not shown, an insulating layer (not shown) may be disposed between the wiring board and the reflection layer380. An insulating resistor R may be disposed between the wiring board and the reflection layer380by the insulating layer. The insulation resistor R may be formed at various positions between the wiring board and the reflection layer380.

When a voltage is applied to the wiring electrodes310to350and the plurality of semiconductor light emitting devices360according to the driving of the light source unit300, a minute leakage current may be generated from the wiring electrodes310to350, and a voltage may be applied to the reflection layer380by the leakage current. For example, the magnitude of the voltage applied to the reflection layer380may be an intermediate value between the first voltage V1and the fifth voltage V5(or an average value of the first voltage V1to the fifth voltage V5), this is not necessarily the case.

Meanwhile, since the voltages applied to each of the wiring electrodes310to350are different from each other, the voltage between the wiring electrodes310to350and the reflection layer380may be different for each location. For example, assuming that the first voltage V1to the fifth voltage V5are sequentially 40V, 30V, 20V, 10V, and 0V, and the voltage applied to the reflection layer380is 20V, a voltage of 20V may be applied between the first wiring electrode310and the reflection layer380. Also, a voltage of 10V may be applied between the second wiring electrode320and the reflection layer380, and a voltage of 0V may be applied between the third wiring electrode330and the reflection layer380. Also, a voltage of −10V may be applied between the fourth wiring electrode340and the reflection layer380and a voltage of −20V may be applied between the fifth wiring electrode350and the reflection layer380.

The maximum voltage deviation applied between the wiring electrodes310to350and the reflection layer380may increase as the number of the wiring electrodes increases. Due to the voltage deviation, an electrochemical phenomenon such as ionic-migration or electro-migration may occur between the wiring electrodes310to350and the reflection layer380. The electrochemical phenomenon may occur more actively as the voltage deviation increases. In this case, metals (copper, gold, etc.) included in the wiring electrodes310to350may be peeled off in the form of metal ions. In particular, the ion migration or electric migration may occur in the wiring electrodes (e.g., the first wiring electrode310and the second wiring electrode320) having a voltage higher than the voltage of the reflection layer380.

As the metal of the wiring electrode is peeled off, an electrical loss may occur when a current is supplied, or the semiconductor light emitting device360may not be lit normally.

Also, the lamp may be in contact with or adjacent to an external environment (such as the atmosphere) to emit light to the outside. In this case, the electrochemical phenomenon may more actively occur according to a change in the external environment (e.g., an increase in temperature and/or humidity). These problems may cause a decrease in the reliability of the lamp.

Various embodiments for solving the above problems will be described below with reference toFIGS.15to17.

FIG.15is a diagram illustrating an embodiment of a reflection layer connected to an external power source according to an embodiment of the present invention.

Referring toFIG.15, the reflection layer380may include a power connection part381connected to an external power source. The power connection part381may be implemented in a form in which a part of the reflection layer380is extended, or a metal of the same material as the reflection layer380is connected to each other.

In this case, a voltage may be applied to the reflection layer380by an external power source connected through the power connection part381. In particular, the voltage applied by the external power source may be applied to minimize peeling of the metal included in the wiring electrodes310to350.

The voltage applied by the external power source may be equal to or greater than the voltage of the wiring electrode (e.g., the first wiring electrode310) to which the highest voltage among the wiring electrodes310to350is applied.

For example, when each of the first voltages V1to V5is sequentially 40V, 30V, 20V, 10V, and 0V, a voltage of 40V may be applied to the reflection layer380. In this case, the voltage applied between the first wiring electrode310and the reflection layer380is 0V, and the voltage applied between the second wiring electrode320and the reflection layer380is −10V. In addition, the voltage applied between the third wiring electrode330and the reflection layer380is −20V, the voltage applied between the fourth wiring electrode340and the reflection layer380is −30V, and the fifth wiring electrode, and a voltage applied between350and the reflection layer380may be −40V.

Since the voltages of the first wiring electrode310and the reflection layer380are the same, an occurrence of an electrochemical phenomenon between the first wiring electrode310and the reflection layer380may be minimized. Also, since the voltage of the second wiring electrode320to the fifth wiring electrode350is lower than the voltage of the reflection layer380, the second wiring electrode320to the fifth wiring electrode350may correspond to the negative pole in relation to is the reflection layer380. Accordingly, it is possible to prevent the metal included in the wiring electrodes310to350from being peeled off due to the migration phenomenon.

That is, according to the embodiment shown inFIG.15, the lamp connects power to the reflection layer380and applies a predetermined voltage, thereby minimizing metal peeling of the wiring electrodes310to350to prevent deterioration of the reliability of the lamp. can

FIG.16is a view showing another embodiment of a reflection layer provided in the lamp shown inFIG.14.

Referring toFIG.16, the reflection layer provided in the light source unit300of the lamp may include a plurality of partial reflection layers382ato382dseparated from each other.

The plurality of partial reflection layers382ato382dmay be separated to correspond to the groups370ato370dof the plurality of semiconductor light emitting devices360. For example, the first partial reflection layer382amay correspond to the region including the first group370a, and the second partial reflection layer382bmay correspond to the region including the second group370b. Also, the third partial reflection layer382cmay correspond to a region including the third group370c, and the fourth partial reflection layer382dmay correspond to a region including the fourth group370d.

In this case, a voltage corresponding to an intermediate value between the first voltage V1of the first wiring electrode310and the second voltage V2of the second wiring electrode320can be applied to the first partial reflection layer382a. Similarly, a voltage corresponding to an intermediate value between the second voltage V2and the third voltage V3can be applied to the second partial reflection layer382b, and a voltage corresponding to an intermediate value of the third voltage V3and the fourth voltage V3can be applied to the third partial reflection layer382c. Also, a voltage corresponding to an intermediate value between the fourth voltage V4and the fifth voltage V5may be applied to the fourth partial reflection layer382d.

Accordingly, a maximum voltage deviation between the wiring electrodes310to350and the partial reflection layers382ato382dcan drop sharply than a maximum voltage deviation between the wiring electrodes310to350and the reflection layer380described inFIG.14. As the voltage deviation decreases, the electrochemical reaction between the wiring electrodes310to350and the partial reflection layers382ato382dis reduced, so that the reliability of the lamp and the light source unit300due to metal peeling can be prevented.

FIG.17is a view showing another embodiment of a reflection layer provided in the lamp shown inFIG.14.

Referring toFIG.17, unlike the embodiment shown inFIG.16, the reflection layer may include a plurality of partial reflection layers384separated to correspond to each of the plurality of semiconductor light emitting devices360provided in the light source unit300.

In this case, similar to the embodiment ofFIG.16, a voltage applied to each of the plurality of partial reflection layers384may correspond to a median value of voltages applied to the corresponding wiring electrodes.

Accordingly, the maximum voltage deviation between the wiring electrodes310to350and the partial reflection layers384may be sharply lower than the maximum voltage deviation between the wiring electrodes310to350and the reflection layer380described above with reference toFIG.14. As the voltage deviation decreases, the electrochemical reaction between the wiring electrodes310to350and the partial reflection layers384decreases, so that the reliability of the lamp and the light source unit300may be prevented from being deteriorated due to metal peeling or the like.

That is, according to the embodiment shown inFIGS.16to17, the reflection layer provided in the light source unit300of the lamp may be divided into a plurality of partial reflection layers so that different voltages are applied thereto. Accordingly, the deviation between the voltage of each of the plurality of partial reflection layers and the voltage of the wiring electrodes corresponding to each of the plurality of partial reflection layers can be reduced, thereby effectively reducing the electrochemical reaction and improving the reliability of the lamp.

Meanwhile, although not shown, the embodiment ofFIG.15and the embodiment ofFIGS.16to17may be integrally applied to the reflection layer. That is, the reflection layer may be divided into a plurality of partial reflection layers, and each of the separated partial reflection layers may be connected to an external power source to receive power.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments.

The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.