Lighting apparatus using PN junction light-emitting element

The present disclosure discloses a lighting apparatus using a PN junction light-emitting element, the apparatus including: a power transmitting substrate having a plurality of boundaries defined thereon; a plurality of PN junction light-emitting elements positioned within each boundary and divided into a plurality of groups; and a first switch provided on the power transmitting substrate, wherein the first switch goes into the ON state by a supplied AC having a first voltage to cause PN junction light-emitting elements of a first group positioned within each boundary to emit light, and the first switch is in the OFF state when PN junction light-emitting elements of a second group, which is positioned within each boundary and connected in series to the first group, emit light by a supplied AC having a second voltage higher than the first voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit and priority of Korean patent Application No. KR-10-2011-0016997, filed Feb. 25, 2011. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure, in general, relates to a lighting apparatus using a PN junction light-emitting element, and more particularly, to a lighting apparatus using a PN junction light-emitting element that has reduced volume and weight.

BACKGROUND

In a lighting apparatus using a PN junction light-emitting element, a light-emitting diode (LED) module having a plurality of LEDs mounted on a power transmitting substrate is typically used as a light source. The LEDs have the advantages of small size, low power consumption and excellent control characteristics, and therefore the LED lighting apparatus can be made slim and lightweight. However, a typical LED lighting apparatus includes a heat sink for heat dissipation or a separate drive circuit for driving an LED module. Elements such as the heat sink or the drive circuit make it difficult to realize a slim and lightweight design of the LED lighting apparatus.

For example, the drive circuit may include an A/D converter to supply DC power, and the A/D converter includes a trans-coil for lowering the voltage of AC. The trans-coil has a drawback in that, since the trans-coil is arranged occupying a large space in the drive circuit, the dimension of the product having the same becomes large.

In order to solve the problems as described above, a power supply device called a switching mode power supply (SMPS) has been recently employed. Here, the SMPS transforms an AC frequency (50 Hz-60 Hz) into a DC frequency, so it requires a high level of technologies.

However, it is necessary for a conventional LED driver using an SMPS to have a noise filter because it uses high-speed switching and hence generates much noise. Besides, it is difficult to configure a circuit at a low cost because a lot of parts are used for circuit configuration. Additionally, the SMPS itself occupies a fairly large size compared to the size of an LED module. As a result, there are limitations on the miniaturization of the LED module and thus of the product itself.

Meanwhile, since the LED module includes a plurality of LEDs, the overall current capacity becomes large. Thus, the conventional LED drive circuit employs an electrolytic capacitor as a part. Such an electrolytic capacitor is suitable for a circuit with high capacitance, but its poor frequency characteristics and relatively high aging degradation reduce the reliability of the circuit. Particularly, in the case of an electrolytic capacitor being mounted, together with an LED, on a power transmitting substrate, the lifespan of the electrolytic capacitor is much shortened due to heat generated by light emission of the LED. Moreover, as the volume of an inductor and a capacitor increases in a circuit having a plurality of LEDs arranged thereon, this may even cause limitations to the exterior design of an LED lighting apparatus.

In addition, as an example of the conventional lighting apparatus, disclosed is a lighting apparatus in which a plurality of PN junction light-emitting elements are arranged in both directions, with their rows being connected in parallel, and used directly for an AC power source without using a separate drive circuit. Voltage is adjusted as needed via a resistor. The PN junction light-emitting elements in one direction emit light when a positive (+) voltage is applied thereto, and the PN junction light-emitting elements in the opposite direction emit light when a negative (−) voltage is applied thereto.

Such a lighting apparatus is advantageous in that a lighting apparatus using a PN junction light-emitting element can be easily implemented without using a separate drive circuit for converting AC into DC, but poses a problem in the use of a dimmer (seeFIG. 2). For instance, if light is dimmed to 5V when 10V is required to drive the PN junction light-emitting elements connected in series, no current conduction occurs. If a dimmer adapted to set the conduction time by on/off is used, the PN junction light-emitting elements basically emit no light at 10V or less so that their emission time is limited. In addition, the conduction time limitation imposed by the dimmer may cause problems such as flickering.

SUMMARY

According to one aspect of the present disclosure, there is provided a lighting apparatus using a PN junction light-emitting element, the apparatus including: a power transmitting substrate having a plurality of boundaries defined on the power transmitting substrate; a plurality of PN junction light-emitting elements positioned within each boundary and divided into a plurality of groups; and a first switch that is provided on the power transmitting substrate, wherein the first switch goes into the ON state by a supplied AC having a first voltage to cause PN junction light-emitting elements of a first group positioned within each boundary to emit light, and the first switch is in the OFF state when PN junction light-emitting elements of a second group, which is positioned within each boundary and connected in series to the first group, emit light by a supplied AC having a second voltage higher than the first voltage.

According to another aspect of the present disclosure, there is provided a lighting apparatus using a PN junction light-emitting element, the apparatus including: a first light-emitting module including a first power transmitting substrate and a plurality of PN junction light-emitting elements provided on the first power transmitting substrate; a second light-emitting module including a second power transmitting substrate electrically connected to the first power transmitting substrate and a plurality of PN junction light-emitting elements provided on the second power transmitting substrate; and a first switch that goes into the ON state by a supplied AC having a first voltage to cause the PN junction light-emitting elements of the first groups positioned on the first power transmitting substrate and the second power transmitting substrate to emit light, and is in the OFF state when the PN junction light-emitting elements of the second groups, which are positioned on the first power transmitting substrate and the second power transmitting substrate and connected in series to the first groups, emit light by a supplied AC having a second voltage higher than the first voltage.

DETAILED DESCRIPTION

The present disclosure will now be described in detail with reference to the accompanying drawings.

FIG. 1is a view showing an example of a lighting apparatus using a PN junction light-emitting element according to the present disclosure.FIG. 2is a view showing examples of a light-emitting element package shown inFIG. 1.FIG. 3is a view showing an example of electrical connections of the lighting apparatus using the PN junction light-emitting element according to the present disclosure.

The lighting apparatus10using the PN junction light-emitting element includes a power transmitting substrate21, a plurality of PN junction light-emitting elements81,82,83,84,85and86, a first switch63, a second switch65, a rectifying circuit61including a bridge diode, and a dimmer3.

The power transmitting substrate21is, for example, a printed circuit board. The power transmitting substrate21may include a metal layer for heat dissipation, a wiring layer, and a connector23. The wiring layer is formed on the metal layer and may include wiring and an insulating layer for insulating the wiring. The power transmitting substrate21may have various shapes, including a disc, a rectangular plate, a linear rod, etc. according to applications of the lighting apparatus10using the PN junction light-emitting element.

As shown inFIG. 1, the connector23may be provided on each of the opposite short-side peripheries of the power transmitting substrate21of an approximately rectangular shape and receives power from an external source. A connection cable40(seeFIG. 5) is coupled to the connector23to apply transmitted power to the connector23. A plurality of lighting apparatuses10using a PN junction light-emitting element may be electrically connected to each other via the connection cable40.

As shown inFIG. 3, the PN junction light-emitting elements81,82,83,84,85and86are mounted on the power transmitting substrate21and emit light by supplied power. A typical example of the PN junction light-emitting element is a light-emitting diode (LED), and another example thereof may include a laser diode (LD). A plurality of boundaries are defined on the power transmitting substrate21.

A boundary is a unit in which the plurality of PN junction light-emitting elements81,82,83,84,85and86are arranged. For example, the boundaries inFIGS. 1 and 2are light-emitting element packages15and16having a plurality of PN junction light-emitting elements81,82,83,84,85and86incorporated thereon. The number and arrangement of light-emitting element packages15and16may vary according to the type and use of the lighting apparatus10using the PN junction light-emitting element, andFIG. 1illustrates the arrangement of the light-emitting element packages15and16in two rows.FIG. 3shows an electrical connection between the first light-emitting element package15and the second light-emitting element package16and the power transmitting substrate21as a representative example of the light-emitting element packages15and16of the first and second rows.

The plurality of PN junction light-emitting elements81,82,83,84,85and86positioned within each boundary, i.e., each light-emitting element package15or16are divided into a plurality of groups. The number of groups may vary depending on the number of PN junction light-emitting elements included in one boundary. For example, as shown inFIGS. 1,2and3, a PN junction light-emitting element81of the first group G1, a PN junction light-emitting element83of the second group G2, and a PN junction light-emitting element85of the third group G3are positioned within the first light-emitting element package15. A PN junction light-emitting element82of the first group G1, a PN junction light-emitting element84of the second group G2, and a PN junction light-emitting element86of the third group G3are positioned within the second light-emitting element package16. As shown inFIG. 2, an input lead line80aand an output lead line80bare individually connected to the three PN junction light-emitting elements81,82,83,84,85and86positioned within each of the first and second light-emitting element packages15and16.

As shown inFIG. 3, the first group G1, the second group G2and the third group G3are connected in series. The PN junction light-emitting elements of the same group may be connected in parallel or in series.FIG. 3illustrates a parallel connection thereof.

The first switch63is connected between the first group G1and the second group G2, and the second switch65is connected between the second group G2and the third group G3. The first switch63goes into the ON state by a supplied AC having a first voltage to cause the PN junction light-emitting elements81and82of the first group G1positioned within the first and second light-emitting element packages15and16to emit light, and is in the OFF state when the PN junction light-emitting elements83and84of the second group G2emit light by a supplied AC having a second voltage higher than the first voltage.

The second switch65goes into the ON state when the first switch63is in the OFF state by the supplied AC having the second voltage, thereby causing the PN junction light-emitting elements83and84of the second group G2to emit light.

In order to drive the PN junction light-emitting elements using AC, the PN junction light-emitting elements connected in series may be arranged in both directions so that the PN junction light-emitting elements arranged in different directions are alternately driven depending on a directional change in current. On the contrary, as shown inFIG. 3, the PN junction light-emitting elements81,82,83,84,85and86may be arranged in one direction, and the rectifying circuit61may be used to supply current in one direction to the PN junction light-emitting elements81,82,83,84,85and86.

FIGS. 4a-care views for explaining changes of the AC voltage caused by the application of a dimmer.

The dimmer3may adjust the brightness of the lighting apparatus10using the PN junction light-emitting element by adjusting the AC voltage.

As shown inFIG. 4a, when the AC voltage reaches V1, the PN junction light-emitting elements81and82of the first group G1can emit light. At this point, if the first switch63is in the ON state, this causes AC to flow, thus enabling the first group G1to emit light. Moreover, when the AC voltage reaches V2, the PN junction light-emitting elements83and84of the second group G2can emit light. At this point, if the first switch63is in the OFF state and the second switch65is in the ON state, the first group G1and the second group G2can emit light. In addition, when the AC voltage reaches V3, the PN junction light-emitting elements85and86of the third group G3can emit light. At this point, if the first switch63and the second switch65are in the OFF state, the first group G1, the second group G2and the third group G3can emit light.

As shown inFIG. 4b, when the maximum voltage is set to a value between V2and V3by the dimmer3, light emission occurs only in the first group G1and the second group G2while no light emission occurs in the third group G3. In the present disclosure, the PN junction light-emitting element81of the first group G1, the PN junction light-emitting element83of the second group G2, and the PN junction light-emitting element85of the third group G3are included in one boundary, for example, the first light-emitting element package15, while the PN junction light-emitting element82of the first group G1, the PN junction light-emitting element84of the second group G2, and the PN junction light-emitting element86of the third group G3are included in another boundary, i.e., the second light-emitting element package16. Thus, light emission occurs in both of the first light-emitting element package15and the second light-emitting element package16positioned throughout the lighting apparatus10even if the third group G3emits no light due to dimming. That is, when the maximum voltage is set to a value between V2and V3by the dimmer3, it is rather dark because there is no section where all of the three PN junction light-emitting elements81,82,83,84,85and86within one boundary emit light. Nevertheless, light emission occurs dimmed over the entire lighting apparatus10using the PN junction light-emitting element.

As shown inFIG. 4c, if dimming is performed by adjusting the conduction time, light is emitted only during half of a period of the AC voltage, thus reducing the overall amount of light. Nevertheless, light emission occurs dimmed over the entire lighting apparatus.

FIG. 5is a view showing an example of the configuration of a switch shown inFIG. 3.

The switches63and65ofFIG. 3can be easily implemented by using an OP-amp comparator OP1for sensing whether the magnitude of an AC voltage of a switching transistor T reaches V1, V2, and V3, respectively, as shown inFIG. 4.

FIG. 6is a view showing an application example of the lighting apparatus using the PN junction light-emitting element according to the present disclosure.FIG. 7is a sectional view taken along line I-I′ shown inFIG. 6.

As shown inFIGS. 6 and 7, the lighting apparatus10using the PN junction light-emitting element may be housed in a casing to thus configure a lighting module5. The casing includes, for example, a bottom cover30and a top cover50.

The lighting apparatus10using the PN junction light-emitting element is disposed on the bottom cover30. The bottom cover30may be made of plastic, and, as shown inFIG. 6, the bottom cover30may have a slot31into which the power transmitting substrate21is to be inserted. Screw fastening holes33are formed at the corners of the bottom cover30. The metal layer of the power transmitting substrate21is in contact with the bottom cover30, and heat generated during the light emission of the PN junction light-emitting elements15is dissipated via the metal layer of the power transmitting substrate21and the bottom cover30.

The lighting module5employing the lighting apparatus10using the PN junction light-emitting element has significantly reduced volume and weight because it has no heat sink having a heat dissipation fin or heat radiation blade. To improve the heat dissipation characteristics, the bottom cover30may be made of heat dissipation plastic having excellent heat dissipation characteristics. Moreover, an excessive temperature rise can be suppressed by decreasing the number of light-emitting element packages15and16mounted on the power transmitting substrate21.

The top cover50is positioned over the power transmitting substrate21and coupled to the bottom cover30. The top cover50may include, as shown inFIGS. 6 and 7, a base portion51, a sloping portion53, and a side portion56.

Openings55corresponding to the light-emitting element packages15and16are formed in the base portion51. The light-emitting element packages15and16may be exposed through the openings55and inserted into the openings55as shown inFIG. 7.

The sloping portion53extends from an edge of the base portion51, and, as shown inFIG. 7, extends upward so as to form an angle of inclination with respect to the base portion51. The sloping portion53corresponds to a periphery of the power transmitting substrate21, and a space is defined between the power transmitting substrate21and the sloping portion53where the above-described first switch63, second switch65, rectifying circuit61, and dimmer3are to be seated.

The side portion56extends downward from the upper end of the sloping portion53and is coupled to the bottom cover30. For example, as shown inFIG. 6, a fastening protrusion54is provided on the side portion56, and the bottom cover30may have a fastening hole into which the fastening protrusion54is inserted in a hook coupling manner. The top cover50may have a screw fastening hole57corresponding to the bottom cover30.

A transparent lens70is positioned over the top cover50as shown inFIGS. 6 and 7, and a guide slot in which the transparent lens70is placed is formed in the upper end of the side portion56of the top cover50. The transparent lens70shields and protects the light-emitting element packages15and16from the outside. The transparent lens70may be made of transparent plastic, and may transmit light coming from the PN junction light-emitting elements and adjust the orientation angle of the light.

As the lighting apparatus10using the PN junction light-emitting element is used for the lighting module as described above, there is no need to use a heat sink and a drive substrate for driving the light-emitting element packages15and16, thus providing the slim and lightweight lighting module5.

FIG. 8is a view showing another example of the lighting apparatus using the PN junction light-emitting element according to the present disclosure.

The lighting apparatus310using the PN junction light-emitting element shown inFIG. 8is substantially identical to the lighting apparatus10using the PN junction light-emitting element explained with reference toFIGS. 1 to 7except that a plurality of light-emitting modules301and303are electrically connected for circuit configuration. Accordingly, duplicate description thereof will be omitted.

A plurality of light-emitting element packages315are arranged on a first power transmitting substrate321to thus configure a first light-emitting module301. A plurality of PN junction light-emitting elements are positioned within a light-emitting element package. The PN junction light-emitting elements within the light-emitting element package are divided into a plurality of groups. A plurality of light-emitting element packages317are arranged on a second power transmitting substrate322to thus configure a second light-emitting module303.

A connection cable340is coupled to a connector to electrically connect the first power transmitting substrate321and the second power transmitting substrate322. Accordingly, the PN junction light-emitting elements of the first group of the first light-emitting module301and the PN junction light-emitting elements of the first group of the second light-emitting module303may be connected in parallel. Also, the PN junction light-emitting elements of the second group of the first light-emitting module301and the PN junction light-emitting elements of the second group of the second light-emitting module303may be connected in parallel.

A first switch, a second switch and a rectifying circuit may be provided on either the first power transmitting substrate321or the second power transmitting substrate322. The first switch goes into the ON state when a supplied AC has a first voltage and causes the PN junction light-emitting elements of the first groups positioned on the first power transmitting substrate321and the second power transmitting substrate322to emit light. When the first switch is in the OFF state by a supplied AC having a second voltage higher than the first voltage, the second switch goes into the ON state and causes the PN junction light-emitting elements of the second groups, which are positioned on the first power transmitting substrate321and the second power transmitting substrate322and connected in series to the first groups, to emit light.

In this manner, lighting apparatuses of various uses and types can be configured by connecting a plurality of light-emitting modules.

Hereinafter, various exemplary embodiments of the present disclosure will be described.

(1) A lighting apparatus using a PN junction light-emitting element, wherein a plurality of PN junction light-emitting elements within a boundary are packaged in a light-emitting element package, and the boundary is defined by the light-emitting element package.

(2) A lighting apparatus using a PN junction light-emitting element, wherein three PN junction light-emitting elements constitute one light-emitting element package, and an input lead line and output lead line are individually connected to each of the PN junction light-emitting elements.

(3) A lighting apparatus using a PN junction light-emitting element, wherein, in the first group, one PN junction light-emitting element positioned within the first boundary and one PN junction light-emitting element positioned within the second boundary are connected in parallel, and in the second group, another PN junction light-emitting element positioned within the first boundary and another PN junction light-emitting element positioned within the second boundary are connected in parallel.

Although PN junction light-emitting elements in a group may be connected either in series or in parallel, the lighting apparatus can more sensitively respond to dimming when they are connected in parallel. For instance, if three PN junction light-emitting elements (which emit light at 3V) are provided in a group, 3V is required for parallel connection while 9V is required for serial connection, and they can respond to the dimmer in units of 3V, not in units of 9V.

(4) A lighting apparatus using a PN junction light-emitting element, wherein the apparatus further includes a second switch that is provided on a power transmitting substrate and goes into the ON state to cause the PN junction light-emitting elements of the second group to emit light when the first switch is in the OFF state by a supplied AC having a second voltage.

This means that groups of PN junction light-emitting elements may be added as needed. For example, if only the PN junction light-emitting elements of the first group and the PN junction light-emitting elements of the second group are positioned within a boundary, the first switch alone may be connected between the first group and the second group.

(5) A lighting apparatus using a PN junction light-emitting element, wherein the PN junction light-emitting elements of the first group and the PN junction light-emitting elements of the second group that are positioned within one boundary are spaced apart from each other on the power transmitting substrate.

A boundary may be defined by one package having a plurality of chips, or by a plurality of chips provided on one substrate, or simply by disposing a plurality of chips or a package in one area. However, it is preferable to use one package to improve the degree of integration of the chips and in consideration of wiring to be required later.

In any method for defining a boundary, light can be emitted uniformly over the entire lighting apparatus according to changes in AC power despite the application of a dimmer by uniformly distributing the PN junction light-emitting elements of each group throughout the lighting apparatus.

(6) A lighting apparatus using a PN junction light-emitting element, wherein the apparatus further includes: a bottom cover positioned under the power transmitting substrate; a top cover positioned over the power transmitting substrate and having openings for exposing the PN junction light-emitting elements; and a transparent lens positioned over the top cover and transmitting light coming from the PN junction light-emitting elements.

This is a preferred embodiment of the lighting apparatus according to this disclosure. With this configuration, the lighting apparatus can emit light without any restrictions caused by a structural change of the first switch or the like accompanied by the use of the dimmer.

(7) A lighting apparatus using a PN junction light-emitting element, wherein the plurality of PN junction light-emitting elements positioned in a first light-emitting module and a second light-emitting module are packaged in light-emitting element packages, and the plurality of PN junction light-emitting elements positioned within each light-emitting element package are divided into a plurality of groups.

(8) A lighting apparatus using a PN junction light-emitting element, wherein the PN junction light-emitting elements of the first group of the first light-emitting module and the PN junction light-emitting elements of the first group of the second light-emitting module are connected in parallel, and the PN junction light-emitting elements of the second group of the first light-emitting module and the PN junction light-emitting elements of the second group of the second light-emitting module are connected in parallel.

In the lighting apparatus using the PN junction light-emitting element according to one aspect of the present disclosure, it is possible to reduce the volume and weight of a lamp employing the lighting apparatus using the PN junction light-emitting element because elements such as PN junction light-emitting elements, switches for driving the PN junction light-emitting elements, and so on are integrally provided on a power transmitting substrate such that no separate drive substrate is required.

Additionally, in the lighting apparatus using the PN junction light-emitting element according to another aspect of the present disclosure, the elements provided on the power transmitting substrate do not include an electrolytic capacitor having low resistance to heat, thereby preventing deterioration of reliability such as lifespan.

Moreover, in the lighting apparatus using the PN junction light-emitting element according to a further aspect of the present disclosure, it is possible to provide a lighting apparatus which is suitable to use AC with dimming.

Further, in the lighting apparatus using the PN junction light-emitting element according to a still further aspect of the present disclosure, it is possible to provide a slim and lightweight lighting apparatus using a PN junction light-emitting element because no heat sink is required and the bottom cover, the power transmitting substrate, the top cover, and the transparent lens have a compact coupling structure.