Fluorescent lamp having V-shaped grooves for guiding lead wire

[0002] The present invention relates to a fluorescent lamp having a fluorescent tube and a lighting circuit board therefor.

[0003] In a conventional fluorescent lamp, for example, a bulb-shaped fluorescent lamp, examples of a method for connecting a lead wire of a fluorescent tube to a lighting circuit board include, for example, a lapping connection. In the lapping connection, as described in Publication of Japanese Patent Application No. Hei 10-275592 A, lapping pins 28, each having a square cross section, are provided on a lighting circuit board as connecting terminals and then lead wires 35 of a fluorescent tube are wound around the lapping pins 28 several times, thereby connecting the lead wires of the fluorescent tube and the lighting circuit board. In another conventional connecting method, Y-shaped connecting terminals are provided on a lighting circuit board and lead wires are inserted into the Y-shaped connecting terminals, thereby connecting the lead wires to the connecting terminals by caulking.

[0004] However, in such conventional bulb-formed fluorescent lamps, when the lead wires of the fluorescent tube are connected to the lighting circuit, the directions in which the lead wires extend are not the same. Therefore, it was extremely difficult to automate the connection by using a machine. Even when the connection is automated, faults are frequently found in that the lead wires cannot properly be connected to the terminals of the lighting circuit.

[0005] Furthermore, the lapping connection takes a long time since each lead wire is wound around each square pin five or six times. Therefore, the assembly operation efficiency is significantly impaired. On the other hand, the caulking connection by using the Y-shaped connecting terminals results in poor contacting due to vibration during transportation of the product even if the caulking is only slightly weak. Therefore, the reliability is not sufficient. Another problem is that the connecting terminal itself is expensive.

[0006] It is an object of the present invention to solve the problems of the prior art. That is, the object of the present invention is to provide a fluorescent lamp in which connecting terminals of a lighting circuit board and lead wires of a fluorescent tube easily can be connected and which is excellent in assembly operation efficiency, cheap and capable of achieving a highly reliable connection.

[0007] In order to achieve the above-mentioned object, a fluorescent lamp of the present invention includes a fluorescent tube, a holder holding the fluorescent tube, a lighting circuit board provided with a lighting circuit for lighting the fluorescent tube, and a case connected to the holder and housing the lighting circuit board. At the end portion of the lighting circuit board, cut-outs are formed, which widen toward an outer side of the lighting circuit board. In the vicinity of the inner narrow portion of each cut-out, the connecting terminal connected to the lighting circuit is provided. Each lead wire of the fluorescent tube is connected to the connecting terminal.

[0008] According to this configuration, since the lead wires of the fluorescent tube easily can be led to the connecting terminals of the lighting circuit board, it is possible to automate the connection between the lead wires and the connecting terminals. Thus, assembly operation efficiency and productivity can be improved.

[0009] In the above-mentioned configuration, the cut-out is V-shaped or Y-shaped. Thus, the lead wires of the fluorescent tube are easily led to the connecting terminals provided on the lighting circuit board, so that the position of the lead wire can easily be matched with the position of the connecting terminal.

[0010] Furthermore, in the above-mentioned configuration, cut-outs, which widen as the distance from the fluorescent tube increases and which are V-shaped or Y-shaped, are provided on a side wall placed on the holder opposite to the fluorescent tube and that the broad portion of the cut-outs of the holder and the broad portion of the cut-outs of the lighting circuit board are arranged facing each other.

[0011] According to this configuration, when the fluorescent tube is attached to the holder, the wires can be held by the side wall after they are bent toward the outer side of the holder. Therefore, after the fluorescent tube is attached to the holder, when the lighting circuit board is attached to the holder, the lead wires of the fluorescent tube are not obstructing to the attachment of the lighting circuit board. Furthermore, since the broad portion of the cut-outs of the lighting circuit board and the broad portions of the cut-outs of the side wall placed on the holder are facing each other, by bending the lead wires, which were bent toward the outer side of the holder, toward the side of the lighting circuit board, the lead wires easily can be led to the connecting terminals of the lighting circuit board. Consequently, the position of the lead wires easily can be matched with the position of the connecting terminals.

[0012] Furthermore, in the above-mentioned configuration, the lead wires of the fluorescent tube are connected to the connecting terminals of the lighting circuit board by welding. Thus, a strong connection between the lead wires of the fluorescent tube and the connecting terminals of the lighting circuit board can be realized, the reliability of the connecting portion is improved and the connection excellent in assembly operation efficiency can be realized.

[0013] Furthermore, the connecting terminal of the lighting circuit board may be a jumper lead wire. Thus, the position of the lead wires of the fluorescent tube can be matched with the position of the connecting terminals of the lighting circuit board more easily, and mass production can be realized o more easily and further cheaply.

[0014] FIG. 1 is a partial cutaway front view showing a bulb-shaped fluorescent lamp in one embodiment according to the present invention.

[0015] FIG. 2 is a bottom view showing the fluorescent lamp of FIG. 1 according to the present invention shown by partially taken away.

[0016] FIG. 3 is a front view showing a part of the fluorescent lamp of FIG. 2.

[0017] FIG. 4 is a bottom view showing a fluorescent lamp in another embodiment according to the present invention shown similar to that of FIG. 2.

[0018] Hereinafter, the present invention will be described by way of embodiments with reference to drawings.

[0019] As shown in FIG. 1, a bulb-shaped fluorescent lamp of the present invention includes a fluorescent tube 1, a lighting circuit board 3a,a holder 2, a case 4 and a base 5. The fluorescent tube 1 is covered with a globe 6. In this structure of the fluorescent tube 1, three U-shaped tubes are joined into one body to form a discharge path therein. On the lighting circuit board 3a,a lighting circuit 3 for lighting the fluorescent tube 1 is mounted. The fluorescent tube 1 and the lighting circuit board 3aare held by the holder 2. The case 4 surrounds the lighting circuit board 3aand is attached to the holder 2. The base 5 is provided on one end of the case 4 opposite to the holder 2.

[0020] Filament coils (not shown) are provided on both ends of the inner side of the fluorescent tube 1. The lead wires 1a,which supply electric current to the filament coils, are led out of the both ends of the fluorescent tube 1.

[0021] FIG. 2 is a bottom view of the fluorescent lamp of FIG. 1, while taking away the case 4 and the base 5 and shows a structure of the part in which the lighting circuit board 3ais connected to the lead wire 1aof the fluorescent tube 1. FIG. 3 is a front view showing the structure of a part of the fluorescent lamp of FIG. 2. The lamp of FIG. 3 is shown so that the orientation is upside down with respect to that of FIG. 1.

[0022] As shown in FIG. 2, Y-shaped cut-outs 3b,which widen toward the outer side of the lighting circuit board 3a,are formed on the portion in which the lead wires 1aof the fluorescent tube 1 are connected to the lighting circuit board 3a.In the vicinity of the inner narrow portion of each Y-shaped cut-out 3b,namely, the vertex of each cut-out 3b,a square pin 3dconnected to each lead wire 1aof the fluorescent tube 1 is provided. The square pin 3dis a connecting terminal of the lighting circuit board 3a.

[0023] With this configuration, when the lead wires 1aand the square pins 3dare connected, the lead wires 1aeasily can be led to the square pins 3dbeing guided by the Y-shaped cut-outs 3b,thus enabling the precise positioning. Moreover, it is possible easily to connect the lead wires 1aand the square pins 3dby, for example, laser welding, or resistance welding, etc.

[0024] The cut-outs 3bmay be V-shaped instead of being Y-shaped. Also, connecting terminals that are Y-shaped, etc., instead of the square pins 3d, may be used.

[0025] In this embodiment, on the side wall 2aformed on the holder opposite to the fluorescent tube 1, V-shaped or Y-shaped cut-outs 2b, which widen as the distance from the fluorescent tube 1 increases, are provided.

[0026] When assembling, when the fluorescent tube 1 is attached to the holder 2, lead wires 1aare inserted into the cut-outs 2band the lead wires are bent toward the outside of the holder 2 in advance. Thereafter, the lighting circuit board 3ais attached to the holder 2 so that the broad portion of the cut-outs 2band the broad portion of the cut-outs 3bof the lighting circuit board 3aare facing each other at about 90°. Thereafter, the lead wires 1athat were bent toward the outside of the holder 2 are inserted into the cut-outs 3bof the lighting circuit board 3a.Thus, the lead wires 1aeasily can be positioned before the lighting circuit board 3ais held by the holder 2. In addition, when the lighting circuit board 3ais attached to the holder 2, the lead wires 1acan be prevented from obstructing the attachment. Consequently, the lighting circuit board 3acan be attached smoothly to the holder 2. Furthermore, each lead wire 1acan easily be led to each square pin 3dthat is a connecting terminal. The precise positioning easily can be performed and a welding connection between the lead wires 1aand the square pins 3dcan be facilitated.

[0027] As mentioned above, since the precise positioning of the lead wires 1aof the fluorescent tube 1 can be realized, the lead wires 1aof the fluorescent tube 1 easily can be connected to the square pins 3dor the Y-shaped connecting terminals by direct laser welding, resistance welding, or the like. Therefore, unlike the conventional lapping connection, the operation does not require a long time, and a connection that is highly reliable and is suitable for mass production can be realized.

[0028] As shown in FIG. 4, as the connecting terminals of the lighting circuit board 3a,jumper lead wires 3cmay be provided spanning each cut-out 3b.If the jumper lead wires 3cand the lead wires 1aof the fluorescent tube 1 are connected by laser welding or resistance welding, the connection which is further reduced in cost and is suitable for mass production can be realized.

[0029] In the above-mentioned embodiments, the lamp having the fluorescent tube 1 in which three U-shaped tubes are joined into one body to form a discharge path inside is explained. However, the present invention is not limited to this alone, and any shapes of the fluorescent tube, for example, four or five U-shaped tubes are bridge-connected, etc. may be employed.

[0030] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not restrictive, the scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.