Light emitting module and illumination apparatus

A light emitting module has a flat light emitting panel including a transparent substrate and a light emitting part formed on the substrate. The flat light panel includes: electrode pads which are formed on the substrate outward of the light emitting part and are electrically connected to the light emitting part; and a transparent or light reflective sealing member which is provided to cover the electrode pad.

FIELD OF THE INVENTION

The present invention relates to a light emitting module including electroluminescence (EL) elements used as a light source, and an illumination apparatus including same.

BACKGROUND OF THE INVENTION

An organic EL element has the ability to emit light with high luminance at a high voltage and with various colors depending on the kind of organic compounds, and can be easily manufactured as a flat light emitting panel. Thus, in recent years, a light emitting module provided with a light emitting panel using organic EL elements has been in the spotlight.

FIG. 10shows this kind of light emitting module. As shown, a light emitting module103includes a light emitting panel102in which a light emitting part122is formed on a transparent substrate121via a transparent electrode122a; and a wiring circuit board106for supplying a power to the light emitting panel102(see, e.g., Japanese Patent Application Publication No. 2007-200627). The light emitting panel102includes an electrode pad123connected to the light emitting part122through the transparent electrode122a; and a sealing tube124which seals the light emitting part122. The wiring board106is fastened to the light emitting panel102by means of a fastener109such as an adhesive tape. The light emitting panel102is electrically connected to the wiring board106by connecting the electrode pad123to an electrode pad162formed on the wiring circuit board106by using a bonding wire108.

However, in the light emitting module103as configured above, some lights “L” of the lights emitted from the light emitting part122are guided in the substrate121without penetrating through the substrate121. The lights L laterally guided in the substrate121are outputted in a lateral direction of the substrate121and in a non-emission direction of the light emitting module103, and thus cannot be used as effective light. As a result, fewer lights are outputted in the front direction of the light emitting module103, thereby deteriorating light use efficiency.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a light emitting module and an illumination apparatus including same, capable of improving light use efficiency by directing lights, which are guided from a light emitting part into a substrate, in the front direction of the light emitting module.

In accordance with an aspect of the present invention, there is provided a light emitting module including a flat light emitting panel having a transparent substrate and a light emitting part formed on the substrate. The flat light panel includes: electrode pads which are formed on the substrate outward of the light emitting part and are electrically connected to the light emitting part; and a transparent or light reflective sealing member which is provided to cover the electrode pad.

The light emitting module may further include a case which covers a non-emission surface of the light emitting panel and has a light reflective surface facing the sealing member.

In the light emitting module, the sealing member may contain a light scattering material.

In the light emitting module, the sealing may be made of a substantially white material.

In the light emitting module, a layer may be formed on a surface of the substrate positioned outward of the light emitting part to diffuse lights outputted from the light emitting part and guided into the substrate.

The light emitting module may be used in an illumination apparatus.

With the light emitting module in accordance with the aspect of the present invention, some of lights guided from the light emitting part into the substrate are incident into the sealing member and are totally reflected into the non-emission surface of the sealing member or are reflected in the interface between the substrate and the sealing member, and thus outputted from the substrate in the front direction of the light emitting module, which can result in improvement in light use efficiency.

DETAILED DESCRIPTION OF THE EMBODIMENTS

A light emitting module and an illumination apparatus including same in accordance with an embodiment of the present invention will now be described with reference toFIGS. 1 to 6which form a part hereof. As shown inFIG. 1, in this embodiment, an illumination apparatus1includes a light emitting module3(a light source part) having a flat light emitting panel2including organic EL elements; and a mounting part4which is detachably mounted on the light emitting module3. The mounting part4is attached to a ceiling or a wall via an installation surface4a, and the light emitting module3is mounted on the mounting part4to emit lights toward a living space and the like.

The light emitting module3includes a transparent cover51which is provided in an emission side (a lower side inFIG. 1) of the light emitting panel2and through which light is emitted; and a case52which is provided to cover a non-emission side (an upper side inFIG. 1) of the light emitting panel2and hold the cover51. The cover51and the case52constitute a package5. This package accommodates therein the light emitting panel2and a wiring circuit board6which is mounted on the non-emission side of the light emitting panel2and supplies a power to the light emitting panel2. The mounting part4includes a circuit board41which controls turning on and off of the light emitting panel2; and a housing42which accommodates the circuit board41therein.

As shown inFIGS. 2 to 4, the light emitting panel2includes a rectangular transparent substrate21; and a light emitting part22in which a light emitting layer and a light reflective cathode are stacked in order, with a patterned transparent electrode (not shown) interposed therebetween, on the substrate21. Materials generally used in manufacturing organic EL elements are also used for a substrate, a transparent electrode (anode), a light emitting layer and a cathode.

On a side of the substrate21on which the wiring board6is provided, light emitting panel-side electrode pads23aand23bare formed at a position outward of the light emitting part22. The electrode pads23aand23bare formed along opposite end portions of the substrate21and are electrically connected to the light emitting part22via a transparent electrode22a(seeFIG. 5which will be described later) and the cathode in such a way that the electrode pads23acorresponding to the anode and the electrode pads23bcorresponding to the cathode are alternately arranged side by side.

As such, by dispersively arranging the electrode pads23aand23baround the light emitting part22, a current flowing into the light emitting part22can be made uniform to thereby uniformalize a surface emission luminance of the light emitting part22. The light emitting part22is covered by a sealing tube24(seeFIG. 5which will be described later) which protects a light emitting layer and the like of the light emitting part22containing an organic material from water, oxygen and the like. The sealing tube24is of a box type corresponding to an external appearance of the cathode side of the light emitting part22and is made of a transparent material such as glass or the like. The electrode pads23aand23bare covered by a sealing resin member7.

For the wiring board6, a member including a flame-retardant and low-conductive substrate having a central-opened frame shape is used. As this substrate, a glass fiber plate, such as FR-4or the like, is used. The glass fiber plate is obtained by impregnating a glass fiber tissue with an epoxy resin or the like and then curing same. The wiring board6has a terminal61which is formed on a surface thereof facing the case52(seeFIG. 1) and electrically connects the wiring substrate6and the circuit board41of the mounting part4. The terminal61includes a fastener61afastened to the wiring board6; and a flat knife-shaped contact portion61berected from the fastener61a. The contact portion61binserted through a groove portion53(seeFIG. 1) formed in the case52and is exposed to the mounting part4. In this example, a pair of terminals61is formed in one end portion of the wiring board6.

In addition, wiring board-side electrode pads62aand62bare formed on the wiring board6in the vicinity of the electrode pads23aand23bwhen viewed from top.

In addition, anode and cathode lines (not shown) electrically connected to the terminals61are formed on the wiring board6. These electrode lines are coated with an insulating material and some portions of the electrode lines are exposed to a surface of the wiring board6opposite to a surface thereof facing the light emitting panel2so as to be connected to the electrode pads62aand62b. The electrode pads62aand62bare respectively wired to the electrode pads23aand23bvia conductive bonding wires8, the electrode pads23aand23bbeing respectively electrically connected to the anode and cathode of the light emitting panel2.. The light emitting panel2and the wiring board6are adhered and fixed together by means of an attachment member9(seeFIG. 5which will be described later), such as an acryl double-sided adhesive tape, containing a core material with high heat resistance, moisture resistance and stress relaxation property.

A configuration of the package5(the cover51and the case52) of the light emitting module3and the mounting part4will be described with reference toFIG. 1. The cover51is of a box shape having an opened surface in the case52side and thus has a light emission surface51athrough which light is emitted from the light emitting panel2; and a sidewall51bwhich is erected from an outer periphery of the light emitting surface51aand covers an outer peripheral surface of the light emitting panel2.

The sidewall51bhas an inner peripheral surface formed to conform to the outer peripheral surface of the light emitting panel2.

Thus, by merely inserting the light emitting panel2into the cover51, it is possible to position the light emitting panel2and the wiring board6with ease. The sidewall51bof the cover51has fitting clicks51cwhich are formed on its peripheral surface to engage the cover51with the case52. The fitting clicks51care formed to project in the circumferential direction of the light emitting surface51aand are provided with a predetermined interval in the outer peripheral surface of the sidewall51b. The cover51may be made of, for example, a plastic resin such as a transparent ABS resin, an acryl resin, a polystyrene resin or the like.

The case52is of a box shape having an opened surface (rear surface) in the cover51side. The case52has a concave main surface52aand a sidewall52bwhich is erected from a periphery of the main surface52aand covers the outer peripheral surface of the sidewall52bof the cover51. The sidewall52bhas fitting grooves (not shown) which are formed in its inner peripheral surface and engage with the fitting clicks51cof the cover51. The fitting grooves are provided at a position in the sidewall52b, corresponding to the fitting clicks51c.

The case52has a front surface whose circumference is formed to be convex in the mounting part4side, and includes a concave wiring board receiving part54which receives the wiring board6in a rear surface of the convex portion. The wiring board receiving part54has a frame shape corresponding to the wiring board6. The case52further includes a pair of engaging portions55formed in one end of its non-emission side. The engaging portions55engage with engaged portions (not shown) formed in a mounting surface4bof the mounting part4on which the light emitting module3is to be mounted. The engaging portions55have their leading ends formed in a hook shape toward the outer side, and the engaged portions of the mounting part4are formed in a shape corresponding to the engaging portions55. In a state where the engaging portions55engaged with the engaged portions, the light emitting module3is rotatable with respect to the mounting part4.

The case52further includes a holding portion56formed in an end of the main surface52aother than its one end in which the engaging portions55are formed. The holding portion56is held in a held portion43which is formed in the mounting surface4bof the mounting part4. Like the engaging portions55, the holding portion56has its leading end formed in a hook shape toward the outer side, and the held portion43is formed in a shape corresponding to the holding portion56. The holding portion56and the held portion43are held under a state where the light emitting module3is mounted on the mounting part4. That is, the light emitting module3is mounted on the mounting part4by engaging the engaging portion55with the engaged portions of the mounting part4and rotating one ends of the engaged engaging portions55by use of the other ends as an axis to engage the holding portion56with the held portion43.

The case52is generally made of the same material as the cover51but may be made of an opaque material such as a metal material, for example, aluminum having a surface subjected to an insulating treatment, the material having an elasticity to allow the sidewall52bto be slightly bent. An angled portion connecting the main surface52aand sidewall52bof the case52is preferably partially chamfered as shown inFIG. 1. This helps to make an external appearance of the light emitting module3slim.

The mounting part4includes a pair of terminal receiving portions44which electrically connect the terminals61(seeFIG. 2) and the circuit board41, in addition to the circuit board41and the housing42. The housing42is formed in a convex shape in the light emitting module3side and has a concave circuit board receiving portion45which receives the circuit board41. In addition, the housing42has through grooves46through which the terminals61are inserted.

A protective member47for protecting the circuit board41is mounted on the circuit board41. The circuit board41is formed of a same material as that of the wiring board6, and various devices (not shown), such as a driver for turning on/off the light emitting panel2and so on, are mounted on a surface of a rectangular base at the side of the light emitting module3. The circuit board41is provided with joining portions to the terminal receiving portions44and external power supply terminals48. The joining portions, the external power supply terminals48, the driver and the like are electrically interconnected by a wiring pattern formed on the circuit board41.

The terminal receiving portions44are a pair of metal pieces bent into an L-like shape and each has one end fixed to the circuit board41and the other end erected toward the light emitting module3, thereby forming a clip-shaped contact point which holds the corresponding terminal61inserted through the through the groove46. Thus, electrical connection between the terminal receiving portions44and the terminals61is achieved.

Next, a joint structure of the light emitting panel2and the wiring board6will be described with reference toFIGS. 5 and 6in addition toFIG. 4.FIG. 5is a side sectional view in a position where the electrode pads62aand the wire8are formed (specifically, taken along line V-V inFIG. 3) andFIG. 6is a side sectional view in a position where the electrode pads62aand the wire8are not formed (specifically, taken along line VI-VI inFIG. 3).FIG. 5shows a section which traverses the electrode pads23aand62acorresponding to the anode.

In the meantime, a section which traverses the electrode pads23band62bcorresponding to the cathode has a different structure of drawing an electrode from the light emitting part22to the electrode pads23bbut has the same joint structure of the electrode pads23band62bas the anode side, and therefore, is not shown for the purpose of avoiding complexity. For the sake of convenience, the cover is not shown inFIGS. 5 and 6and the transparent electrode22aof the light emitting part22is not shown inFIG. 6. This is true in modifications of the embodiment, which will be described later.

The wiring board6is adhered and fixed to the sealing tube24by means of the attachment member9such as an adhesive tape or the like. The attachment member9is provided immediately below a portion where the electrode pads62aand62bare formed in a surface of the wiring board6facing the sealing tube24. The attachment member9may be arranged either in the form of dots corresponding to the electrode pads62aand62bor in the form of lines conforming to the electrode pads62aand62b(seeFIG. 3). In a state where the light emitting panel2and the wiring board6are fixed together, the electrode pads62aand62bare wired to the electrode pads23aand23bby means of the wire8.

A plurality of (3in this example) wires8are preferably provided to wire the electrode pads. This can makes it possible to prevent electrical connection between the electrode pads from being cut even if any wire8is disconnected but if the remaining wires8are not disconnected, which can result in uniform emission of the light emitting part22. An example of the wires8may include a pure aluminum line which can bond conductive layers of each electrode terminal in a short time at a room temperature by means of ultrasonic bonding.

A diameter of the wire8is determined in consideration of current consumption, material and so on of the light emitting panel2. For example, if a current consumed is1A, a wire having a line diameter of more than 100 μm with a fusing current of2A is used in consideration of a safety factor of 50%. The wire8may be a copper or gold wire instead of the aluminum wire.

After completing the boding of the wire8, the sealing resin member7is provided to cover the electrode pads23aand23bfrom a side end of the sealing tube24sealing the light emitting part22.

The sealing resin member7is made of a transparent resin material such as, for example, a silicone resin, an epoxy resin or the like. If such a resin material has a refractive index which is equal to or greater than that of the substrate21, it is possible to prevent total reflection at an interface between the substrate21and the sealing resin member7. The sealing resin member7is formed by applying its resin material by a dispenser or the like in such a way that the resin material covers the electrode pads23aand23bfrom the side end of the sealing tube24. That is, along with a bonded end of the wire8, the electrode pads23aand23bare covered by the sealing resin member7. At this time, when the resin material is applied, the sealing resin member7has a low fluidity near the side end of the wire8and the side end of the sealing tube24, which increases a thickness of the sealing resin member7near the side end of the wire8and the side end of the sealing tube24but decreases a thickness thereof toward the periphery of the substrate21. Consequently, a surface of the sealing resin member7facing the case52has a slope inclined toward the periphery of the substrate21.

With the above configuration, as shown inFIG. 6, some, e.g., lights L1, of lights propagated from the light emitting part22into the substrate21are incident into the sealing resin member7and totally reflected from an interface of the sealing resin member7facing the case52. Then, the totally reflected lights L1are transmitted through the substrate21and outputted from the substrate21in a light irradiation (front) direction of the light emitting module3. In addition, lights L2incident from the substrate21into the sealing tube24are also incident from the side end of the sealing tube24into the sealing resin member7, and then are outputted from the substrate21after being totally reflected from the interface.

In addition, the case52is configured to have a light reflective surface facing the sealing resin member7. For example, a surface facing the sealing resin member7is coated with a material having a high light reflectivity, such as a white paint or the like, or a highly light reflective metal film. With this configuration, lights L3incident into the sealing resin member7with a small incidence angle with respect to the interface of the sealing resin member7are transmitted through the sealing resin member7without being totally reflected, but are reflected by the case52. The light L3are transmitted through the sealing resin member7and the substrate21, and are outputted in the front direction of the light emitting module3. In addition, since an end of the case52is formed to be inclined, the lights L3transmitted through the sealing resin member7can be effectively reflected. Further, lights L4outputted laterally from the light emitting part22and incident into the sealing tube24without being incident into the substrate21are also incident into the sealing member7and outputted in the front direction of the light emitting module3.

With the light emitting module3as configured above, it is possible to improve light use efficiency by drawing light, which guided from the light emitting part22into the substrate21, in the front direction of the light emitting module3. In addition, by providing the sealing resin member7, it is possible to protect a bonding portion between the electrode pads23aand23band the wire8while preventing water, oxygen and the like from permeating into the light emitting part22. A light emitting module3in accordance with a modification of the above-described embodiment will be now described with reference toFIG. 7. The light emitting module3in accordance with this modification includes a sealing resin member7containing a light scattering material71. An example of the light scattering material71may include, for example, light scattering particles of titanium oxide or the like.

With this configuration, lights L5incident into the sealing resin member7are reflected and diffused by the light scattering material71, and are thus outputted in the front direction of the light emitting module3. In addition, among the lights diffused by the light scattering material71, lights guided in a non-emission surface direction are totally reflected from an interface of the sealing resin member7facing the case52or are reflected by the case52and drawn in the front direction of the light emitting module3. Consequently, like the above-described embodiment, in accordance with this modification, it is possible to improve light use efficiency by drawing light, which guided from the light emitting part22into the substrate21, in the front direction of the light emitting module3.

A light emitting module3in accordance with another modification of the above-described embodiment will be now described with reference toFIG. 8. The light emitting module3in accordance with this modification includes a sealing resin member7′ that is mainly made of a white material. With this configuration, some, e.g., lights L6, of lights guided from the light emitting part22into the substrate21are reflected from an interface between the substrate21and the sealing resin member7′ and are thus outputted in the front direction of the light emitting module3. Consequently, this modification provides a less amount of lost light outputted from the sealing resin member7′ to the case52side, which may result in high light use efficiency.

A light emitting module3in accordance with still another modification of the above-described embodiment will be now described with reference toFIG. 9. The light emitting module3in accordance with this modification includes a diffusing layer21awhich is formed on the substrate outside the sealing tube24(or the light emitting part22) and diffuses lights outputted from the light emitting part22and guided into the substrate21. The sealing resin member7′ is made of the same white material as in the above-described another modification. The diffusing layer21ais formed by printing a reflective material on the substrate or subjecting the substrate21to a grooving processing or a micro prism processing.

With this configuration, the diffusing layer21aserves to suppress the total reflection of lights L7which are incident and guided from the light emitting part22into the substrate21and reflect the lights L7by the white sealing resin member7′, thereby drawing lights in the front direction of the light emitting module3. In addition, the diffusing layer21amay be used in combination with the transparent resin material7shown inFIGS. 5 and 6or the sealing resin member7containing the light scattering material71shown inFIG. 7.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.

For example, the electrode pads62aand62bmay be covered by a resin member in order to protect the wire8bonded to the electrode pads62aand62b. In addition, this resin member may be integrated with the sealing resin member7which covers the above-described electrode pads23aand23b. Moreover, the sealing rein which covers the electrode pads62aand62bis preferably formed such that its height is lower than the top of head of the arc-like wired8. This helps to make the light emitting module3slim without increasing the thickness of the light emitting panel3.