WO2009095308A1

WO2009095308A1 - Electronic ballast casing and electronic ballast having the same

Info

Publication number: WO2009095308A1
Application number: PCT/EP2009/050420
Authority: WO
Inventors: Martin Niedermaier; Rene Twardzik
Original assignee: Osram Gesellschaft mit beschränkter Haftung
Priority date: 2008-02-01
Filing date: 2009-01-15
Publication date: 2009-08-06
Also published as: CN201171241Y; EP2248405A1

Abstract

The present utility model discloses an electronic ballast casing and an electronic ballast having the same. Particularly, the electronic ballast casing is an integrally formed tubular member. The electronic ballast casing in accordance with the present utility model reduces the complexity of the product and thus facilitates a manufacturing process of the same and reduces its manufacturing cost.

Description

ELECTRONIC BALLAST CASING AND ELECTRONIC BALLAST HAVING THE SAME

TECHNICAL FIELD

I ill I The present utility model relates to electronic products, and especially to an electronic ballast casing and an electronic ballast having the same.

BACKGROUND OF THE INVENTION

I il^ ] It has been well known that an electronic ballast is a crucial member for most fluorescent lamps which is adapted to energize the fluorescent lamp by a high voltage. An example of an electronic ballast according to the prior art is shown in FIGl. As shown, the electronic ballast generally designated by reference numeral 100 includes a hollow casing and electronic components 103 and 107 mounted within the casing. Particularly, the hollow casing consists of a plurality of members mainly comprising a main body 101 and two end caps 102. The main body 101 is formed with mounting holes in side walls thereof through which fasteners such as screws 104 may be inserted to fasten the electronic components 103 and 107 to inner side walls. The two end caps 102 may be snapped onto both end portions of the main body 101 respectively and are both formed with a plurality of ventilation holes 111. Usually, in order to facilitate mounting the electronic components 103 and 107, the main body 101 is formed by bending at least two thin plate members and being connected together by fasteners such as screws.

I (131 The above-mentioned electronic ballast casing includes a plurality of members such as end caps 102 and the main body 101 which must be manufactured with a relatively high precision to meet assembly requirements, and additionally a process for assembling the plurality of members together is time-consuming, thereby leading to a relatively high cost.

I (141 Moreover, an insulating plate is required if the casing is formed from metal, and thus the manufacturing cost of the casing will be further increased.

|i!5 I Therefore, an improved casing design is required.

SUMMARY OF THE INVENTION

| ()f>l The present utility model is just made in view of the problems as mentioned above. An object of the present utility model is to provide an electronic ballast casing with a relatively low cost and a relatively simple structure and assembling process, and an electronic ballast having the same.

I I)T I According to an aspect of the present utility model, there is provided an electronic ballast casing characterized in that it is an integrally formed tubular member.

1081 According to another aspect of the present utility model, there is provided an electronic ballast including an electronic ballast casing and an electronic assembly disposed in the electronic ballast casing, characterized in that the electronic ballast casing is an integrally formed tubular member.

I D^ I According to the present utility model, since the electronic ballast casing is integrally formed, a time-consuming and thus cost-consuming assembly process in the prior art is eliminated. That is, the cost may be reduced. Further, since it is easy and convenient to fix the electronic assembly within the casing by means of potting materials or a fixing stick, the electronic ballast having the above-mentioned electronic ballast casing may have a reduced cost of manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS

I 111 I FIG. 1 is a prospective view showing an example of an electronic ballast casing in accordance with the prior art.

11 I f FIG. 2 is a prospective view showing an electronic ballast in accordance with the present utility model, with electronic assembly mounted therein.

112 \ FIG. 3 is a front view of the electronic ballast as shown in FIG.2.

I 131 FIG 4 is a top view of the electronic ballast as shown in FIG.2.

I 141 FIG 5a is a schematic sectional view taken along line A-A in FIG. 4, especially showing a first embodiment of fixing the PCB with the fixing stick.

I 151 FIG. 5b-5d are schematic sectional views taken along line A-A in FIG. 4, showing another embodiment of fixing the PCB with the fixing stick

I 11^ I FIG. 6 is an end view of the electronic ballast as shown in FIG.2, viewed from an end portion of the electronic ballast towards interior thereof. DESCRIPTION OF THE PREFERRED EMBODIMENT

1 17 I The present utility model will be described in detail hereinafter with reference to the drawings.

1181 Referring FIGs. 2 to 4, an appearance and structure of an electronic ballast including a casing in accordance with the present utility model is shown.

I IΛ⁾ \ The electronic ballast in accordance with the present utility model includes a hollow casing generally designated by reference numeral 1 and electronic assembly mounted within the casing. In accordance with the present utility model, the hollow casing is an integrally formed tubular member, which is preferably molded from plastics by injection molding. It should be appreciated that the electronic ballast casing may be integrally formed from any other suitable material by any other suitable manufacturing process.

|2il | In the embodiment as shown, the electronic ballast casing 1 has a symmetric structure with both ends opened. Further, the casing 1 has a predetermined length and cross-sectional shape to accommodate the electronic assembly 6 which usually includes a PCB (Printed

Circuit Board) 61 and a plurality of electronic components 62 mounted thereon. Preferably, as shown in FIG.6, the electronic ballast casing 1 has a rectangular cross section. Moreover, the electronic ballast casing 1 is beveled at each end portion thereof to expose a mounting hole 11 formed in a bottom wall of the casing which is used to facilitate connecting the electronic ballast to or removing it from other structures.

I 2.1 I In order to mount the electronic assembly 6 within a desired position in the casing 1, the electronic ballast casing 1 in accordance with the present utility model is formed with supporting portions for supporting PCB and allowing PCB to slide thereon. In a preferred embodiment, as shown in FIG. 6, the supporting portions are two guiding and supporting ribs 7 which protrude oppositely from lower portions of the inner sides of both side walls of the casing 1 and extend in a longitudinal direction of the casing 1. The two guiding and supporting ribs 7 protrude from the inner side walls of the casing 1 respectively by a predetermined distance to thus reliably support PCB 61 from opposite edges of a bottom surface of PCB.

I 221 During ^a producing process of the electronic ballast, the electronic assembly 6 may be inserted sidewise from the opened end of the casing 1 and slide on the guiding and supporting ribs 7 to a final desired position. Then, the electronic assembly 6 may be fixed within the casing 1 by predetermined methods which will be described hereinafter.

I 231 Unlike the conventional casing as previously described, the electronic ballast casing in accordance with the present utility model does not comprise any end cap. Instead, the openings at both ends of the electronic ballast casing are closed by sheltering members 63 carried by PCB, as shown in FIG. 6. The sheltering members 63 may completely close the openings at both ends of the casing, and alternatively may only close lower portions of the openings and leave upper portions of the openings for ventilation. The sheltering member 63 may be a certain electronic component with a suitable cross section profile which simultaneously plays a role in the circuit of the electronic assembly, such as a capacitor or an inductor.

I 241 As shown in FIGs. 2 and 4, in order to fix the electronic assembly 6 within the casing 1, the casing 1 is formed with a first through hole 2 in a top wall thereof. According to one aspect of the present utility model, after the electronic assembly 6 is placed to the desired position via the end opening of the casing 1, suitable potting material such as thermosetting resins may be potted into the casing 1 via the first through hole 2. Thus, the electronic assembly 6 may be fixed in place after the potting material is hardened. According to particular application situations, the potting material may fill the whole space defined by the hollow casing or just submerge PCB 61 of the electronic assembly. It should be appreciated that the potting material will not overflow out of both ends of the casing since the end openings of the casing 1 are closed by the sheltering members 63. In addition to the fixing function, the potting materials may be beneficially used for heat dissipation of the electronic assembly. Even, the potting materials may be used for the only purpose of heat dissipation of the electronic assembly and PCB is fixed in other suitable manners.

125 I Referring to FIG. 5a, another method for fixing the electronic assembly 6 within the casing 1 is illustrated. Here, PCB 61 is formed with a fixing hole 4. A fixing stick 3 is inserted through the first through hole 2 of the casing 1 and the fixing hole 4 to fix PCB 61 and in turn the electronic assembly 6 relative to the casing 1. Particularly, the fixing stick 3 is designed such that a rear end thereof is tightly fixed in the first through hole 2 when a front end 5 thereof is inserted though the first through hole 2 and then is tightly inserted into the fixing hole 4 of PCB 61. Thus, PCB 61 may be fixed relative to the casing 1 by means of the fixing stick 3. | 2l>l Here, the rear end of the fixing stick 3 is sized or constructed such that it may be clamped within the first through hole 2. In the embodiment shown in FIG.5a, the rear end of the fixing stick 3 is constructed as a structure having a plurality of elastic fingers 32. Preferably the plurality of elastic fingers 32 are distributed uniformly along a periphery of a main body of the fixing stick. In a free state thereof before being mounted into the casing, each finger extends out from a main body of the fixing stick 3, and preferably extends substantially perpendicular to an axis of the main body of the fixing stick. Thus, when the fixing stick 3 is inserted through the first through hole 2 and the fixing hole 4, the plurality of elastic fingers is squeezed by the first through hole 2. Once the fixing stick 3 is completely inserted into its final position, the squeezed plurality of elastic fingers allow the fixing stick to be reliably clamped within the first through hole 2.

|2? \ Another embodiment of fixing PCB with a fixing stick is shown in FIGs. 5b-5d. According to this embodiment, in addition to the first through hole 2 in the top wall, the casing 1 is further provided in the bottom wall with a second through hole 2' in align with the first through hole 2.

|28 f Particularly, the diameter of the second through hole 2' is decreased from an outer side of the bottom wall to an inner side of the bottom wall so that the second through hole 2' having minimum diameter is adapted to tightly mating with a front end portion of the fixing stick, which will be described in detail hereinafter. It is preferred to form the second through hole as a stepped hole (as shown) or a tapered bore.

1291 In this embodiment, the fixing stick 3 is a plastic rivet inserted consecutively through the first through hole 2 in the top wall, the fixing hole 4 in PCB and the second through hole 2' in the bottom wall with its front end protruding out of the second through hole 2' . Here, the first through hole 2 is sized to stop a rear end of the plastic rivet. For example, for a plastic rivet with a tapered rear end, the first through hole 2 is preferably formed as a tapered bore to cooperate with the tapered surface of the rear end of the plastic rivet. Similarly, for a plastic rivet with a stepped rear end, the first through hole 2 is preferably formed as a stepped hole. Preferably, the first through hole 2 is sized such that the rear end of the plastic rivet is registered with the top wall of the casing 1 when it is stopped by the first through hole 2.

1301 In this way, when the plastic rivet is inserted into a final position (i.e. when the rear end thereof is stopped by the first through hole 2), the front end of the plastic rivet protruding out of the second through hole 2' is deformed, thereby preventing the front end retreating from the second through hole 2'. It may be achieved by a heat metal bar 9 as shown in FIG. 5c. The heat metal bar 9 has a predetermined temperature so as to enable thermally deformation of the front end of the plastic rivet when contacting with the front end and thus enable enlargement of the front end. Thus, after the heat metal bar is moved away, the plastic rivet may not retreat from the second through hole 2' due to the swelled front end.

| 3 l ] Thus, an movement of the plastic rivet is prohibited by the front end cooperating with the second through hole 2' and the rear end cooperating with the first through hole 2. That is, the plastic rivet is fixed relative to the casing 1. In turn, in a horizontal direction, PCB is fixed relative to the casing 1.

132 ] Further, preferably, the plastic rivet 3 has a stepped portion formed by a front portion with a relatively small diameter and a rear portion with a relatively large diameter. Preferably, only the front portion with a relatively small diameter of the plastic rivet 3 passes through the fixing hole 4 in the PCB, and the stepped portion approaches or abuts an upper surface of the PCB when the rear end is stopped by the first through hole 2 so as to restrict an ascending movement of PCB. Since PCB is simultaneously supported by the supporting ribs 7 from its lower surface, PCB is prevented from moving vertically or is just allowed to move slightly in the vertical direction.

|33 ^ Moreover, there is another manner to fix the electronic assembly. Particularly, after the electronic assembly is placed in the desired position, each side wall of the casing may be thermally pressed inwards from a position around middle height thereof, to thus form a locally recessed cross section which may clamp the electronic assembly in position with a suitable clamping force

|34 ^ Depending on specific application environments, the above manners for fixing the electronic assembly may be used individually or in combination. Preferably, the electronic assembly may be preliminarily fixed by the fixing stick or compressing side walls of the casing, and then may be further fixed by potting materials potted through the first through hole

2. Further, as mentioned previously, the potting materials may be used for the purpose of assisting heat dissipation of the electronic assembly instead of fixing PCB. At this regard, PCB is firstly inserted sidewise into the casing by a predetermined distance. When an component which requires potting materials is aligned with the first through hole 2 of the casing in a vertical direction, a desired amount of potting materials is potted through the first through hole 2. Then keeping moving PCB until all components requiring potting materials are applied with the materials. Finally, fixing PCB with the above-mentioned fixing stick when PCB is inserted into its final position.

I Further, the casing 1 is designed such that electrical terminals are still accessible for electrical connections. As shown in FIG. 6, connectors 8 of the electronic assembly 6 shall be designed to locate outsides of the sheltering member 63 to thus facilitate electrical connections.

I ^f>! Although the preferred embodiment of the present utility model has been disclosed for illustrative purposes, those skilled in the art will appreciate various modifications, additions and substitutions, without departing from the scope and spirit of the utility model as disclosed in the accompanying claims.

Claims

WHAT IS CLAIMED IS:

1. An electronic ballast casing characterized in that it is an integrally formed tubular member.

2. The electronic ballast casing as set forth in claim 1, characterized in that it has a rectangular cross section and has a symmetric structure with both ends opened.

3. The electronic ballast casing as set forth in claim 2, characterized in that the electronic ballast casing is formed at lower portion of inner side walls thereof with supporting ribs for supporting an electronic assembly of the electronic ballast, and the supporting ribs protrude oppositely from lower portions of inner side walls respectively by a predetermined distance and extend along an longitudinal direction of the casing.

4. The electronic ballast casing as set forth in claim 1, characterized in that a first through hole is formed in a top wall of the casing, through which potting materials is allowed to be potted into the casing and/or through which a fixing member for fixing the electronic assembly is allowed to be inserted.

5. The electronic ballast casing as set forth in claim 4, characterized in that a second through hole in align with the first through hole is formed in a bottom wall of the casing.

6. An electronic ballast including an electronic ballast casing and an electronic assembly disposed in the electronic ballast casing, characterized in that the electronic ballast casing is an integrally formed tubular member.

7. The electronic ballast as set forth in claim 6 characterized in that the electronic ballast casing has a rectangular cross section and has a symmetric structure with both ends opened.

8. The electronic ballast as set forth in claim 7, characterized in that the electronic ballast casing is formed at lower portion of inner side walls thereof with supporting ribs on which the electronic assembly is supported, and the supporting ribs protrude oppositely from lower portions of the inner side walls respectively by a predetermined distance and extend along an longitudinal direction of the casing.

9. The electronic ballast as set forth in claim 8, characterized in that the electronic ballast casing is formed with a first through hole in a top wall thereof.

10 . The electronic ballast as set forth in claim 9, characterized in that it further comprises a fixing stick, and in that PCB of the electronic assembly is formed with a fixing hole, the fixing stick being designed such that a rear end thereof is tightly fixed in the first through hole in the top wall of the casing when a front end thereof is tightly inserted into the fixing hole of PCB, thereby fixing the electronic assembly relative to the casing.

11 . The electronic ballast as set forth in claim 10, characterized in that the rear end of the fixing stick has a structure having a plurality of elastic fingers which extend out from a main body of the fixing stick so that, when the fixing stick is inserted into its final position, the plurality of elastic fingers is squeezed and clamped within the first through hole so as to secure the fixing stick within the first through hole.

12. The electronic ballast as set forth in claim 10, characterized in that the electronic ballast casing is formed in a bottom wall thereof with a second through hole in align with the first through hole, and said ballast includes a plastic rivet which is inserted consecutively through the first through hole in the top wall, a fixing hole in PCB of the electronic assembly and the second through hole in the bottom wall, and a movement of the plastic rivet being prohibited by the cooperation between a front end of the plastic rivet and the second through hole, and the cooperation between a rear end of the plastic rivet and the first through hole.

13. The electronic ballast as set forth in claim 12, characterized in that the rear end of the plastic rivet is stopped by the first through hole, and the front end of the plastic rivet having passed through the second through hole is thermally deformed so as to form an enlarged end portion which is mated with the second through hole.

14. The electronic ballast as set forth in claim 12 or 13, characterized in that the plastic rivet has a stepped portion which is formed by a front portion with a relatively small diameter and a rear portion with a relatively large diameter and abuts an upper surface of the PCB of the electronic assembly.

15. The electronic ballast as set forth in any of claims 7-13 characterized in that both opened ends of the casing are closed or partially closed by predetermined electronic components in the electronic assembly.

16. The electronic ballast as set forth in claim 14 characterized in that both opened ends of the casing are closed or partially closed by predetermined electronic components in the electronic assembly.