Lamp using semiconductor light-emitting elements

Discussed is a lamp or a lighting device including a wiring substrate; a bus electrode provided on the wiring substrate; a plurality of electrode lines provided on the wiring substrate, and extending from the bus electrode, each electrode line having one end and a central portion located between the one end and the bus electrode; a plurality of semiconductor light-emitting elements aligned along an extending direction of the plurality of electrode lines, and disposed to be spaced apart from adjacent electrode lines of the plurality of electrode lines by varying distances, respectively; and a plurality of transparent electrodes that respectively provide an electrical connection between the plurality of electrode lines and the plurality of semiconductor light-emitting elements, wherein the respective varying distances between the plurality of semiconductor light-emitting elements and each of the adjacent electrode lines decrease toward the central portion of the each electrode line.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2018/004348, filed on Apr. 13, 2018, which claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2018-0010191, filed in the Republic of Korea on Jan. 26, 2018, the contents of all these applications are hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to a lamp using semiconductor light-emitting elements, and more particularly, a lamp with high light uniformity.

BACKGROUND

Lamps that emit light are used in various fields. For example, a vehicle is equipped with various lamps having lighting functions and signaling functions. Referring toFIG. 1, a lamp device (vehicle lamp)10is provided in a vehicle1to increase illumination for improving visibility of the vehicle1and to indicate a driving state of the vehicle1to other vehicles.

A vehicle or automotive lamp device includes a headlamp installed at the front of a vehicle and a rear lamp installed at the rear of the vehicle. The headlamp provides forward illumination during night driving. The rear lamp includes a stop (or brake) lamp turned on when the brake is pressed, and a turn signal lamp (or direction-indicator lamp) that indicates a proceeding direction of the vehicle.

Halogen lamps or gas discharge lamps have been usually used, but in recent years, light emitting diodes (LEDs) are in the spotlight as light sources for automotive lamps.

The LEDs can enhance a degree of freedom for design of a lamp by minimizing a size thereof and exhibit economical efficiency by virtue of a semi-permanent lifespan, but most of the LEDs are currently produced in a form of a package. The LED itself other than the package is under development as a semiconductor light-emitting element (or device) of converting a current into light, namely, an image displaying light source used in an electronic device such as an information communication device.

However, automotive lamps developed to date use LEDs in the package form, and thus have disadvantages, such as a low mass production yield rate, high fabrication costs, and low flexibility.

Meanwhile, a lamp using semiconductor light-emitting elements may have various areas. When the lamp has a large area, a voltage is not evenly or uniformly applied to individual elements, thereby leading to a decrease in light uniformity.

DISCLOSURE

Technical Problem

One aspect of the present disclosure is to provide a structure that can apply a uniform voltage to semiconductor light-emitting elements provided in a lamp.

Technical Solution

Embodiments disclosed herein provide a lamp that may include a wiring substrate, a bus electrode provided on the wiring substrate, a plurality of electrode lines provided on the wiring substrate, extending from the bus electrode and each having one end, a plurality of semiconductor light-emitting elements aligned along a direction that the electrode lines are formed and disposed to be spaced apart from adjacent electrode lines by a predetermined distance, and a plurality of transparent electrodes that provides electrical connection between the electrode lines and the semiconductor light-emitting elements. The distance between the semiconductor light-emitting elements and each of the electrode lines may decrease toward a central portion of the electrode line.

In one embodiment, the distance between the electrode lines and the semiconductor light-emitting elements may increase toward the bus electrode or the one end.

In one embodiment, a width of each of the electrode lines may increase toward the central portion thereof.

In one embodiment, each of the electrode lines may include a plurality of protrusions protruding perpendicular to a direction that the electrode line is formed.

In one embodiment, a length of each of the protrusions may increase toward the central portion of the electrode line.

In one embodiment, the transparent electrode may be electrically connected to the protrusion and extend in a protruding direction of the protrusion so as to be electrically connected to the semiconductor light-emitting element.

In one embodiment, a length of each of the protrusions may be greater than the distance between the electrode line and the semiconductor light-emitting element.

In one embodiment, the transparent electrode may be electrically connected to the protrusion and extend in a direction that the electrode line is formed so as to be electrically connected to the semiconductor light-emitting element.

In one embodiment, the bus electrode may include a first bus electrode and a second bus electrode, and the first and second bus electrodes may be inclined with respect to each other.

In one embodiment, the electrode line may include a first electrode line extending from the first bus electrode and a second electrode line extending from the second bus electrode. The first electrode line may protrude in a direction perpendicular to the first bus electrode, and the second electrode line may protrude in a direction inclined to the second bus electrode.

Advantageous Effects

According to at least one of the embodiments of the present disclosure, a uniform voltage is applied to semiconductor light-emitting elements provided in a lamp, each of the semiconductor light-emitting elements provided in the lamp can emit light with the same brightness.

BEST MODE OF CARRYING OUT EMBODIMENTS

Description will now be given in detail according to exemplary embodiments disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components may be provided with the same or similar reference numbers, and description thereof will not be repeated. In general, a suffix such as “module” and “unit” may be used to refer to elements or components. Use of such a suffix herein is merely intended to facilitate description of the specification, and the suffix itself is not intended to give any special meaning or function. In describing the present disclosure, if a detailed explanation for a related known function or construction is considered to unnecessarily divert the main point of the present disclosure, such explanation has been omitted but would be understood by those skilled in the art. The accompanying drawings are used to help easily understand the technical idea of the present disclosure and it should be understood that the idea of the present disclosure is not limited by the accompanying drawings.

It will be understood that when an element such as a layer, area or substrate is referred to as being “on” another element, it can be directly on the element, or one or more intervening elements may also be present.

A lamp disclosed herein may include a mobile phone, a smart phone, a laptop computer, a digital broadcast terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation, a slate PC, a tablet PC, an ultrabook, a digital TV, a desktop computer, and the like. However, it will be readily apparent to those skilled in the art that the configuration according to the embodiments described herein may also be applied to a new product type that will be developed later if it is a lamp.

Meanwhile, the lamp described in this specification may be used in a vehicle. Vehicle lamps may include a headlamp, a tail lamp, a position lamp, a fog lamp, a turn signal lamp, a stop (or brake) lamp, an emergency lamp, a backup lamp, and the like.

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

The vehicle lamp10according to one embodiment of the present disclosure includes 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 fixed to the vehicle body directly or by using a bracket. As illustrated, the vehicle lamp10may be provided with a lens unit to more diffuse and sharpen light emitted from the light source unit12.

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

In a non-curved state of the light source unit12(e.g., a state having an infinite radius of curvature, hereinafter, referred to as a “first state”), the light source unit12is flat. When the first state is switched to a state that the light source unit12is bent by an external force (e.g., 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 with at least part curved or bent.

A pixel of the light source unit12may be implemented by a semiconductor light-emitting element. The present disclosure exemplarily illustrates a light-emitting diode (LED) as a type of semiconductor light-emitting element for converting a current into light. The LED has a small size, thereby serving as a pixel even in the second state.

Meanwhile, the light source unit12according to the present disclosure includes a unit light source, a base substrate, and a connection (or connecting) electrode. Hereinafter, the above-mentioned constituent elements (components) will be described in detail.

The light source unit12may be provided with only the unit light source. Hereinafter, the unit light source will be described in detail based on the light source unit12provided with only the unit light source.

FIG. 3is a planar view of an area A inFIG. 2,FIG. 4is a conceptual view of a flip chip type semiconductor light-emitting element,FIG. 5is an enlarged view of an area B inFIG. 3, andFIG. 6is a cross-sectional view taken along line “V-V” ofFIG. 3.

As illustrated, the light source unit12includes a wiring substrate100, a first electrode line110, a second electrode line120, a transparent electrode130, and a semiconductor light-emitting element150. Hereinafter, the components will be described in detail.

Referring toFIG. 3, a plurality of electrode lines may be disposed on the wiring substrate100. Each of the electrode lines110and120may protrude from bus electrodes110′ and120′, respectively, and extends in one direction to have a bar shape. Meanwhile, each of the electrode lines110and120has one end located opposite to the bus electrodes110′ and120′.

When the electrode lines110and120are described as a bar, each having two ends, then one end of the electrode line is connected to the bus electrode, and another end thereof is located opposite to the bus electrode. In this specification, an intermediate point between the opposite ends of the electrode line will be referred to as a “central portion” of the electrode line.

Meanwhile, two types of bus electrodes may be disposed on the wiring board100, namely the first and second bus electrodes110′ and120′ are provided. A voltage applied between the first and second bus electrodes110′ and120′ is applied to each of the semiconductor light-emitting elements150. This allows each of the semiconductor light-emitting elements150to emit light. The first and second electrode lines110and120respectively extending from the first and second bus electrodes110′ and120′ are electrically connected to the semiconductor light-emitting elements150, so that the voltage applied between the first and second bus electrodes110′ and120′ is applied to each of the semiconductor light-emitting elements150.

Here, individual semiconductor light-emitting elements150should be electrically connected to the first and second electrode lines110and120, respectively. Before discussing a structure in which the semiconductor light-emitting elements150are electrically connected to the electrode lines, a structure of the semiconductor light-emitting elements150will be described.

Referring toFIG. 4, the semiconductor light-emitting element150may be a flip chip type light-emitting element.

For example, the semiconductor light-emitting element150includes a p-type electrode156, a p-type semiconductor layer155on which the p-type electrode156is formed, an active layer154formed on the p-type semiconductor layer155, an n-type semiconductor layer153formed on the active layer154, and an n-type electrode152formed on the n-type semiconductor layer153with being spaced apart from the p-type electrode156in a horizontal direction. Here, the p-type electrode156may be electrically connected to the first electrode line110, and the n-type electrode152may be electrically connected to the second electrode line120.

Referring toFIG. 6, in the lamp according to the present disclosure, the p-type electrode and the n-type electrode are disposed in a direction of a light emitting surface. That is, light emitted from the lamp according to the present disclosure is discharged to the outside by passing through the p-type electrode and the n-type electrode. Due to this structural feature, structures that overlap with the semiconductor light-emitting elements should be minimized to increase an amount (or quantity) of light of the lamp.

Meanwhile, in order to maximize the amount of light of the lamp, a reflective layer (or reflector)160may be disposed at an opposite side of a light emitting surface of the semiconductor light-emitting element150. The reflective layer160reflects light emitted from the semiconductor light-emitting element150and directed downward of the lamp, so as to increase the amount of light of the lamp. The reflective layer160may be formed on a base substrate170.

When the first and second electrode lines110and120made of metal or alloy are electrically connected to the semiconductor light-emitting element150in a direct manner, the amount of light of the lamp may be reduced because the first and second electrode lines110and120cover or block the light emitting surface of the semiconductor light-emitting element150. To prevent this, each of the first and second electrode lines110and120is electrically connected to the semiconductor light-emitting element150through the transparent electrode130.

The transparent electrode130may be made of a material having high light transmittance and conductivity. For example, the transparent electrode130may be Indium Tin Oxide (ITO). The transparent electrode130has much higher light transmittance than the first and second electrode lines110and120, but has lower electrical conductivity. As illustrated inFIG. 6, when the semiconductor light-emitting element150overlaps the transparent electrode130, a decrease in the amount of light of the lamp may be minimized.

However, electrical conductivity of the transparent electrode130is lower than that of the first and second electrode lines110and120, a voltage drop may occur. This will be described in detail with reference toFIG. 7.FIG. 7is a graph showing a magnitude of voltage applied to semiconductor light-emitting elements according to a distance between bus electrodes and the semiconductor light-emitting elements in a lamp illustrated inFIG. 3.

As illustrated, a voltage is gradually decreased as the semiconductor light-emitting element is further away from the first bus electrode, and is then increased again. That is, a voltage applied to semiconductor light-emitting elements adjacent to the central portion of the electrode line is lower than a voltage applied to semiconductor light-emitting elements adjacent to the opposite ends of the electrode line. Accordingly, the amount of light emitted from the semiconductor light-emitting elements varies depending on positions of the semiconductor light-emitting elements. As the area of the lamp increases, the difference in the amount of light becomes more apparent.

In order to solve this problem, which is due to a voltage drop, the present disclosure provides a structure that has uniform voltage distribution regardless of the positions of the semiconductor light-emitting elements. The lamp according to the present disclosure may include all of the components described inFIGS. 3 to 6. However, the lamp according to the present disclosure has an electrode structure different from the above-described electrode lines and the bus electrodes.

FIG. 8is a conceptual view illustrating a lamp according to one embodiment of the present disclosure.

Although the transparent electrode130is not illustrated inFIG. 8, the first and second electrode lines110and120are electrically connected to the semiconductor light-emitting element150through the transparent electrode130, as described inFIG. 5.

The lamp according to the present disclosure includes a plurality of semiconductor light-emitting elements150. The plurality of semiconductor light-emitting elements150is aligned along a direction in which the electrode line is formed. Here, the semiconductor light-emitting elements150are disposed to be spaced apart from adjacent electrode lines by a predetermined distance. The distance between the semiconductor-light emitting elements150and each electrode line decreases toward the central portion of the electrode line. In contrast, the distance increases as the semiconductor light-emitting element is disposed closer to the bus electrode, or disposed closer to one end of the electrode line located opposite the bus electrode.

In one embodiment, referring toFIG. 8, a width of each of the electrode lines may increase toward the central portion of the electrode line, so that the distance between the semiconductor light-emitting elements and each of the electrode lines increases. Accordingly, the electrode line has a convex shape in a direction in which the semiconductor light-emitting elements are disposed.

Meanwhile, both the first and second electrode lines110and120may have the convex shape. When the first and second electrode lines110and120are disposed parallel to each other, and the central portions of the first and second electrode lines110and120are located on the same line, the distance between the semiconductor light-emitting elements and electrode lines decreases toward the central portions of the first and second electrode lines110and120.

As the distance between the semiconductor light-emitting element and the electrode line is smaller, an amount of voltage drop is reduced. With this structure, the amount of voltage drop in the central portion of the electrode line is less than the both ends of the electrode line, allowing the same voltage to be applied to all of the semiconductor light-emitting elements provided in the lamp.

Therefore, a voltage applied to the semiconductor light-emitting elements may be controlled by adjusting the distance between the electrode lines and the semiconductor light-emitting elements. Hereinafter, another embodiment of the present disclosure will be described.

In this embodiment, a uniform voltage may be applied to the semiconductor light-emitting elements while the width of each of the electrode lines disposed on the wiring board is constant.

FIGS. 9 to 12are conceptual views of a lamp including an electrode line having a protrusion.

As illustrated inFIG. 9, each of the plurality of electrode lines may be provided with protrusions (or protruding portions)111and121formed perpendicular to a direction in which the electrode line is provided. Each of the protrusions111and121protrudes in a direction in which the semiconductor light-emitting element150is disposed. The protrusions111and121do not overlap the semiconductor light-emitting element150.

As the protrusion is made of a metal having high electrical conductivity, like the electrode line, it serves to narrow the distance between the semiconductor light-emitting element and the electrode line. As illustrated inFIG. 10, the transparent electrode130is provided in a direction in which the protrusions111and121protrude, so as to electrically connect the protrusions111,121and the semiconductor light-emitting element150. When the protrusion111and the semiconductor light-emitting element150are electrically connected, a substantial decrease in distance between the first electrode line110and the semiconductor light-emitting element150is achieved.

Meanwhile, as shown inFIG. 9, a length of the protrusions111ato111eand121ato121emay vary depending on their positions. In detail, the length of the protrusions may increase toward the central portion of the electrode line. Accordingly, the length of the protrusion121edisposed at the central portion of the electrode line may be greater (or longer) than the length of the protrusion121alocated adjacent to the bus electrode. Likewise, the length of the protrusion111edisposed at the central portion of the electrode line may be greater than the length of the protrusion111alocated adjacent to one end of the electrode line.

Further, as shown inFIG. 11, the protrusion111formed on the first electrode line110and the protrusion121formed on the second electrode line120are not necessarily disposed on the same line. In this case, the transparent electrodes130may be alternately disposed to each other, namely, a transparent electrode that electrically connects the first electrode line110and the semiconductor light-emitting element150, and a transparent electrode that electrically connects the second electrode line110and the semiconductor light-emitting element150are alternately disposed.

Therefore, the protrusions of the electrode line have different lengths according to their positions. This may allow a magnitude of voltage applied to the semiconductor-light emitting elements to be uniform.

Meanwhile, in the lamp according to the present disclosure, a uniform voltage may be applied to the semiconductor light-emitting elements even when the protrusions have the same length.

Referring toFIG. 12, the length of the protrusions111and121formed on the electrode lines110and120, respectively, may be greater than the distance between the electrode line and the semiconductor light-emitting element. When the protrusion protrudes to a position where the semiconductor light-emitting element is disposed, the protrusion overlaps the semiconductor light-emitting element. To prevent this, the protrusion protrudes to a position where the semiconductor light-emitting element is not disposed.

Here, the transparent electrode130is electrically connected to the protrusions111and121, and extends along the direction in which the electrode line is formed so as to be electrically connected to the semiconductor light-emitting element. In the structure ofFIG. 12, the width of each of the protrusions111and121may increase toward the central portion of the electrode line. As the width of the protrusion is thicker, a voltage applied to the semiconductor light-emitting element may be increased. By utilizing this, the amount of voltage drop in the central portion of the electrode line may be reduced.

According to the structures described with reference toFIGS. 8 to 12, the same voltage may be applied regardless of the position of the semiconductor light-emitting element. More specifically, as shown in a graph ofFIG. 13, a voltage difference between Vanode (or anode voltage) and Vcathode (or cathode voltage) may be constantly maintained by using the structures of the present disclosure. This may allow light uniformity of the lamp to be improved.

Meanwhile, the lamp according to the present disclosure may apply a uniform voltage to the semiconductor light-emitting elements through arrangement of the bus electrode.

FIG. 14is a conceptual view illustrating an electrode structure of the lamp according to the present disclosure.

As illustrated inFIG. 14, a second bus electrode120′ may be inclined with respect to the first bus electrode110′. In detail, as illustrated in an area “C”, the second bus electrode120′ may be obliquely formed in a direction that the first bus electrode110′ is provided, thereby adjusting the amount of voltage drop within the lamp.

Here, the first electrode line110protrudes perpendicularly (or vertically) from the first bus electrode110′, whereas the second electrode line120inclinedly protrudes from the second bus electrode120′.

In the electrode structure ofFIG. 14, when the semiconductor light-emitting element is disposed between the first and second electrode lines110and120, a uniform voltage may be applied to the semiconductor light-emitting elements. This may allow light uniformity of the lamp to be increased.

As described above, according to the present disclosure, as a uniform voltage is applied to the semiconductor light-emitting elements provided in the lamp, each of the semiconductor light-emitting elements provided in the lamp may emit light with the same brightness.

The aforementioned lamp using the semiconductor light-emitting elements is not limited to the configuration and the method of the embodiments described above, but the embodiments may be configured such that all or some of the embodiments are selectively combined so that various modifications can be made.