FLUORESCENT LAMP AND CONNECTING SYSTEM OF FLUORESCENT LAMP

TECHNICAL FIELD

The present invention relates to a fluorescent lamp used for a lighting device such as a back light incorporated into a liquid crystal device. The present further relates to a connecting system of connecting the fluorescent lamp to the lighting device.

BACKGROUND

There are provided various types of fluorescent lamps used for a back light accommodated in a housing. For example, Official gazette of JP-A-2002-124308 discloses a fluorescent lamp used as a back light for illuminating a liquid crystal display unit from the back side or used as an edge light for illuminating a liquid crystal display unit from the side. Electric power is supplied to this fluorescent lamp by a structure in which a feeder line having a terminal fitting is connected to a terminal of the fluorescent lamp. In this structure, terminal fittings having an insertion hole is crimped at end portions of two feeder lines connected to a connector. Lead terminals provided at both end portions of a cold-cathode tube are inserted into insertion holes of the terminal fittings and brazed. In this way, the working property can be enhanced.

In general, brazing work needs much manpower. Therefore, brazing work is not suitably used for automatization. Therefore, for example, Official gazette of JP-A-6- 290620 discloses a socket used for a fluorescent lamp capable of detachably attaching the fluorescent lamp having two metallic cap pins at each end portion without brazing. This socket can be easily detachably attached by providing a movable piece which comes into contact with a metallic cap pin of a fluorescent lamp and rotated at the time of attaching the fluorescent lamp. In order to easily attach and detach a socket, another example of the socket used for a fluorescent lamp is disclosed in Official gazette of JP-A-6-290620 which does not have a common fluorescent lamp metallic cap pin. This fluorescent lamp includes a hemispherical protruding joint portion and an annular electrically contacting portion at each end portion. When each electrically contacting portion comes into contact with a pin- like electrically contacting portion which is arranged in the socket and pushed in a direction of the fluorescent lamp, electric power can be supplied.

Brazing used in the structure disclosed in Official gazette of JP-A-2002-124308 is

highly reliable from the electrical and mechanical viewpoints. However, it is necessary to conduct the brazing work manually. That is, the brazing work is complicated. On the other hand, in the structure disclosed in Official gazette of JP-A-6-290620, it is unnecessary to conduct the brazing work. However, a target of the device disclosed in Official gazette of JP-A-6-290620 is a common fluorescent lamp in which two metallic cap pins are arranged in parallel in each end portion. Accordingly, at the time of attaching the fluorescent lamp to the socket, it is necessary to adjust a position in the rotary direction with respect to the longitudinal axis of the fluorescent lamp. For the above reasons, the technique described in Official gazette of JP-A-6-290620 is not suitably applied to the automatization of the assembling step of the back light device including the attaching work of the fluorescent lamp.

In the structure described in Official gazette of JP-A-2001-167856, it is unnecessary to pay attention to a position in the rotary direction with respect to the longitudinal axis of the fluorescent lamp. However, a direction of connecting the fluorescent lamp to the socket coincides with the longitudinal direction of the fluorescent lamp. Accordingly, this case is not suitably applied to the automatization including an attaching work of the fluorescent lamp.

In this connection, in the structure described in Official gazette of JP-A-6-290620 or Official gazette of JP-A-2001-167856, the fluorescent lamp is detachably attached to a fixed socket. Therefore, when an error of positioning the socket with respect to a board is large, the fluorescent lamp is given undesirable stress. Especially, an electrode of the fluorescent lamp is given undesirable stress. In the case where a plurality of fluorescent lamps are arranged in parallel so that they can be used as a back light device, parts and wires for supplying electric power to the fluorescent lamps are not arranged on an upper face of the board on which the fluorescent lamps are arranged but the parts and wires for supplying electric power to the fluorescent lamps are mounted on a back side of the board in many cases.

SUMMARY

Therefore, an object of the present invention is to provide a fluorescent lamp and a connecting system of connecting the fluorescent lamp characterized in that: the fluorescent lamp can be assembled without conducting a complicated brazing work; the reliability of the electrical connection of the fluorescent lamp is high; and an assembling work

including attaching the fluorescent lamp can be easily automatized. Another object of the present invention is to provide a connecting system of connecting a fluorescent lamp characterized in that: no stress is given to an electrode of the fluorescent lamp at the time of attaching and detaching the fluorescent lamp; and parts for supplying electric power can be easily arranged on a back side of the board on which the fluorescent lamp is arranged. In order to accomplish the above object, at least one embodiment of the invention provides a fluorescent lamp comprising: a glass tube; and a metallic cap arranged at least in one of the end portions of the glass tube, wherein the metallic cap has at least two electrodes insulated from each other and the two electrodes are formed of cylindrical shapes, which are concentrical to each other, made of a conductive material.

Another embodiment of the invention provides a fluorescent lamp comprising a filament extending from at least one end portion of the glass tube, wherein the end portions of the filament are respectively inserted into the metallic cap and connected to two electrodes. Another embodiment of the invention provides a fluorescent lamp wherein the outer diameters of the two electrodes are different from each other.

Another embodiment of the invention provides a fluorescent lamp connecting system in which the fluorescent lamp is connected to a board comprising: a board connector for receiving the fluorescent lamp and electrically connecting the fluorescent lamp to the board being arranged on the board; and a cover engaging with the board connector and holding the fluorescent lamp in cooperation with the board connector. Another embodiment of the invention provides a fluorescent lamp connecting system wherein the board connector includes at least two terminals made of a conductive material, each of at least two terminals has an electrode holding portion for holding a cylindrical side of each of at least two electrodes of the fluorescent lamp and also has a board connecting portion electrically connected to the board when the board connector is arranged on the board.

Another embodiment of the invention provides a fluorescent lamp connecting system wherein the board connector includes at least two electrode accommodating portions for accommodating each of at least two electrodes of the fluorescent lamp, at least two electrode accommodating portions are open in a direction substantially perpendicular to the board, and the cover is connected to the board connector when the cover is moved in

a direction substantially perpendicular to the board.

Another embodiment of the invention provides a fluorescent lamp connecting system for electrically connecting a fluorescent lamp, which has a glass tube and an electrode provided at at least one end portion of the glass tube, to a board, comprising: a flexible lead wire, one end of which is connected to the electrode of the fluorescent lamp; a flexible insulating tube, one end of which is attached to the electrode of the fluorescent lamp, for covering the lead wire; a plug connector, which is electrically connected to the other end of the lead wire, for holding the other end of the insulating tube; and a socket connector, which is engaged with the plug connector, capable of being electrically connected with the board.

Another embodiment of the invention provides a fluorescent lamp connecting system wherein the socket connector can be attached to a side of the board opposite to the side on which the fluorescent lamp is attached.

At least two electrodes of the fluorescent lamp of the present invention are arranged being symmetrical to each other in any position in the rotary direction with respect to the longitudinal axis of the fluorescent lamp. Therefore, when the fluorescent lamp is attached to a connector, it is unnecessary to give consideration to the position in the rotary direction. Accordingly, an assembling step including a step, in which the fluorescent lamp is attached, can be easily automatized. The fluorescent lamp can be simply composed in such a manner that a filament extending from at least one end portion of the glass tube is inserted into a metallic cap and end portions of the filament are respectively connected to two electrodes.

The fluorescent lamp can be easily electrically connected to the board by the board connector for receiving the fluorescent lamp arranged on the board and by the cover, which is engaged with the board connector, for holding the fluorescent lamp in cooperation with the board connector.

When the terminal having the electrode holding portion for holding each electrode of the fluorescent lamp and also having the board connecting portion electrically connected to the board when the board connector is arranged on the board is arranged in the board connector, the fluorescent lamp and the board can be more simply electrically connected to each other.

The fluorescent lamp is composed in such a manner that the electrode

accommodating portion of the board connector for accommodating each electrode of the fluorescent lamp is open in a direction substantially perpendicular to the board and further the cover is engaged with the board connector when the cover is moved in a direction substantially perpendicular to the board. Due to the above structure, a main operating direction in the assembling step of the fluorescent lamp connecting system can be substantially restricted in a direction perpendicular to the board. Accordingly, the assembling step can be easily automatized.

The electrode of the fluorescent lamp and the plug connector are connected to each other by the lead wire covered with the flexible insulating tube. Due to the above structure, when the fluorescent lamp is attached, it is possible to prevent the electrode from being given stress. Further, the socket connector engaged with the plug connector can be arranged at an arbitrary position on the board. Therefore, the degree of freedom of designing can be enhanced.

The socket connector can be arranged on a lower side of the board which is a side opposite to an upper side of the board on which the fluorescent lamp is attached.

Therefore, when the device is used for a back light device in which an arrangement of parts on the upper side of the board must be avoided, the above structure can be advantageously adopted.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 is a perspective view showing appearance of a fluorescent lamp of the first embodiment of the present invention.

Fig. 2 is an exploded perspective view showing the fluorescent lamp of Fig. 1. Fig. 3 is a sectional view in the axial direction of the fluorescent lamp of Fig. 1. Fig. 4 is a perspective view showing appearance of a board connector for accommodating a fluorescent lamp.

Fig. 5 is a perspective view showing appearance of a cover for holding a fluorescent lamp in cooperation with a board connector.

Fig. 6 is an exploded perspective view showing a system of electrically connecting a fluorescent lamp to a board by using a board connector and a cover. Fig. 7 is a view showing a state in which a fluorescent lamp is accommodated in a board connector.

Fig. 8 is a view showing a state in which a fluorescent lamp has been attached in

the connecting system shown in Fig. 6.

Fig. 9 is a view showing an example in which the connecting system shown in Figs. 6 to 8 is applied to the use of a back light.

Fig. 10 is a perspective view showing appearance of a fluorescent lamp of another embodiment of the present invention.

Fig. 11 is a perspective view showing appearance of the fluorescent lamp shown in Fig. 10 and the plug connector connected to a lead wire of the fluorescent lamp.

Fig. 12 is a perspective view showing appearance of a socket connector engaged with a plug connector. Fig. 13 is an exploded perspective view showing a system of electrically connecting a fluorescent lamp to a board by using a plug connector and a socket connector.

Fig. 14 is a view showing a state in which a fluorescent lamp has been attached in the connecting system shown in Fig. 13. Fig. 15 is a view showing an example in which the connecting system shown in

Figs. 13 and 14 is applied to the use of a back light.

DETAILED DESCRIPTION

Figs. 1 and 2 are views showing a fluorescent lamp 1 of the present invention. At an end portion of a glass tube 11 , a filament 111 for supplying electric power is arranged. At the end portion of the glass tube 11, a metallic cap 2 is provided. The metallic cap 2 has first and second electrodes 21, 22. Both electrodes have cylindrical outside faces 211, 221 made of conductive material such as metal. These cylindrical outside faces 211, 221 are arranged being concentrical to each other. It is necessary for both electrodes to be insulated from each other. Therefore, an insulating portion 23 made of insulating material is arranged between both electrodes.

The metallic cap 2 includes a first filament connecting portion 24 and a second filament connecting portion 25 for connecting a first end portion 112 and a second end portion 113 of the filament 111 to the electrodes 21, 22. At the filament connecting portions 24, 25, the filament end portions 112, 113 are respectively connected to the electrodes 21, 22. In this connection, as long as the filament connecting portion can electrically connect the corresponding filament end portion to the electrode, the filament connecting portion may be arranged at any portion. However, it is preferable that the

filament connecting portion is arranged at an end face portion of each cylindrical shape so that the filament connecting portion can not be contacted with a terminal of a board connector when the filament connecting portion is connected to the board connector described later. Fig. 3 is a sectional view taken in the axial direction of the fluorescent lamp 1. The end portions 112, 113 of the filament 111 are inserted into the metallic cap 2 and extend to the filament connecting portions 24, 24. In each filament connecting portion, the filament is mechanically and electrically connected and fixed by means of brazing or caulking. In the example shown in the drawing, the filament connecting portion is somewhat protruded from the end face of each electrode. However, the filament connecting portion is not used for connecting with the board connector. Therefore, the filament connecting portion may be formed being arranged on the same face as the end face of each electrode. Alternatively, the filament connecting portion may be formed being a little withdrawn from the end face of each electrode. In this connection, an example of the material of the filament is a so-called Dumet wire made of iron-nickel alloy, the surface of which is covered with a copper layer.

Next, a system, in which the fluorescent lamp 1 is connected to the board, will be explained as follows. Fig. 4 is a view showing the board connector 3 in which the fluorescent lamp 1 is accommodated. The board connector 3 includes: a first electrode accommodating portion 31 for accommodating the first electrode 21 of the fluorescent lamp 1; and a second electrode accommodating portion 32 for accommodating the second electrode 22 of the fluorescent lamp 1. In the first electrode accommodating portion, the first terminal 4 is arranged. In the second electrode accommodating portion, the second terminal 5 is arranged. The first terminal 4 and the second terminal 5 are respectively made of conductive material such as copper alloy. The first terminal 4 has a first electrode holding portion 41, which is made of conductive material such as copper alloy, capable of holding the cylindrical outer side face 211 of the first electrode 21. The second terminal 5 has a second electrode holding portion 51 , which is made of conductive material such as copper alloy, capable of holding the cylindrical outer side face 221 of the second electrode 22. The first and the second electrode 21, 22 are respectively fixed into the corresponding accommodating portions by means of press-fitting.

The first electrode accommodating portion 31 and the second electrode

accommodating portion 32 are defined and divided from each other by a first wall 33. The first wall 33 includes a groove 331 capable of receiving the second electrode 22 of the fluorescent lamp 1. The first electrode accommodating portion 31 includes a support face 311 capable of supporting the first electrode 21 of the fluorescent lamp 1. An opposite side to the first wall 33 of the second electrode accommodating portion 32 is defined by a second wall 34. The second wall 34 includes a groove 341 capable of receiving the second filament connecting portion 25 of the second electrode 22.

Fig. 5 is a view showing a cover 6 for pushing the fluorescent lamp 1 accommodated in the board connector 3. The cover 6 includes: a latch 61 capable of engaging with an engaging portion 35 (shown in Fig. 4) such as a hole formed on the outer face of the board connector 3; a first electrode pushing portion 62 for pushing the first electrode 21 of the fluorescent lamp 1 so that the first electrode 21 can be fixed into the first accommodating portion 31 of the board connector 3; a second electrode pushing portion 63 for pushing the second electrode 22 of the fluorescent lamp 1 so that the second electrode 22 can be fixed into the second accommodating portion 32 of the board connector 3; and a guide portion 64 guided by a guide groove 36 (shown in Fig. 4) of the board connector 3.

Fig. 6 is an exploded perspective view showing a system in which the fluorescent lamp 1 is electrically connected to the board 7 when the board connector 3 and the cover 6 described before are used. Fig. 7 is a view showing a state in which the fluorescent lamp 1 is accommodated in the board connector 3 before the cover 6 is attached. As shown in Fig. 6, the terminals 4, 5, which are fixed in the board connector 3, respectively have board connecting portions 42, 52 protruded from the lower side of the connector. These board connecting portions 42, 52 are engaged with through-holes 71 formed on the board 7. Due to the above structure, the terminals and the board 7 are electrically connected to each other. In this connection, the terminals and the board can be connected to each other by means of surface mounting without providing through-holes on the board 7.

As shown in Fig. 7, the first electrode 21 of the fluorescent lamp 1 is electrically connected to the first terminal 4 in the first electrode accommodating portion 31 of the board connector 3. On the other hand, the second electrode 22 of the fluorescent lamp 1 is electrically connected to the second terminal 5 in the second electrode accommodating portion 32 of the board connector 3. To be in more detail, the cylindrical outside face 211

(shown in Fig. 1) of the first electrode 21 is held by and contacted with the electrode holding portion 41. The cylindrical outside face 221 (shown in Fig. 1) of the second electrode 22 is held by and contacted with the electrode holding portion 51. When the thickness of the first wall 33 and that of the second wall 34 of the board connector 3 are adjusted, it is possible to positively connect the terminal with the electrode. It is also possible to positively insulate one terminal from the other. Further, it is possible to positively insulate one electrode from the other. Furthermore, it is possible to effectively avoid the occurrence of interference of the filament connecting portion of each electrode with the board connector. As described before, two electrodes of the fluorescent lamp 1 are respectively formed into a concentrical cylindrical shape. Therefore, it can be said that the fluorescent lamp 1 is substantially symmetrical in the rotary direction at all angles with respect to its axis. Accordingly, as shown in Fig. 6, when the fluorescent lamp 1 is accommodated in the board connector 3 from the top and further pushed by the cover 6 from the top in the same manner, the fluorescent lamp 1 can be positively fixed without paying attention to the angular position of the fluorescent lamp 1 with respect to the rotary shaft. Accordingly, the fluorescent lamp of the present invention can be connected and fixed to the board connector only by a motion substantially conducted in the vertical direction. This means that the working property can be enhanced by the present invention and that the present invention can be easily applied to the automatization.

Fig. 8 is a view showing a state in which the board connector 3 and the cover 6 are engaged with each other and the fluorescent lamp 1 has been attached. In this state, the first electrode 21 of the fluorescent lamp 1 is held by the support face 311 (shown in Fig. 4) of the board connector 3 and the first electrode pushing portion 62 (shown in Fig. 5) of the cover 6. Therefore, it is possible to fix the fluorescent lamp without damaging a glass portion of the fluorescent lamp. In this connection, in the example shown in the drawing, the cover 6 and the board connector 3 are members different from each other. However, as long as the above action can be taken, the cover 6 may be connected to the board connector 3 by a rotary mechanism such as a hinge. Further, the following structure may be adopted. The first electrode 21 of the fluorescent lamp 1 is divided into a portion having an electrical connecting function and a portion not having an electrical connecting function, that is, an insulated portion, and the latter is held.

In this connection, in the above embodiment, an outer diameter of the first electrode 21 and that of the second electrode 22 are concentrical to and different from each other. However, the following structure may be adopted. The outer diameter of the first electrode 21 and that of the second electrode 22 are concentrical and equal to each other and the first electrode 21 and the second electrode 22 are arranged being adjacent to each other in the longitudinal direction of the fluorescent lamp through an insulating portion although this structure is not shown in the drawing. In the case where the outer diameters are equal to each other or in the case where the outer diameters are different from each other, a connecting portion of the electrode with the filament can be arranged on an end face of the electrode. Compared with a case in which the connecting portion of the electrode with the filament is arranged on the side, a case in which the connecting portion of the electrode with the filament is arranged on the end face of the electrode is advantageous in that the metallic cap can be easily assembled. In the case where the outer diameter of the second electrode is made to be smaller than the outer diameter of the first electrode, the connecting portion of the electrode with the filament can be arranged on an end face of each electrode. Therefore, the structure of the electrode (metallic cap) can be made simpler.

In this connection, as shown in Fig. 4, the electrode holding portion of each terminal in the board connector 3 is provided with plate members, the number of which is two on one side, so that a positive electrical connection can be attained even when a cylindrical shape of each electrode is a little deformed. However, as long as a predetermined electrical connection can be accomplished, the number of the plate members may be one or three or more. As shown in Fig. 6, each terminal is provided with a plurality of board connecting portions. However, as long as a predetermined electrical connection can be attained, the number of the board connecting portions may be appropriately selected.

Fig. 9 is a view showing an example in which the connecting system shown in Figs. 6 to 8 is applied to the use of a back light. A plurality of fluorescent lamps 1 are arranged in a row and each fluorescent lamp 1 is electrically connected to the board 7 by the board connector 3 and the cover 6. According to the present invention, any of the board connector 3, the fluorescent lamp 1 and the cover 6 can be arranged at predetermined positions by a simple action conducted from the upper face side to the

lower face side of the board 7. Further, concerning the fluorescent lamp 1, it is unnecessary to pay attention to the rotary direction of the longitudinal axis of the fluorescent lamp 1. Accordingly, the assembling property of the fluorescent lamp 1 is excellent and further the assembling work can be easily automatized. In this connection, in the example shown in the drawing, the plurality of board connectors are respectively different members. However, it is possible to integrate these members into one body so that the members can be formed into an array shape. Concerning the plurality of covers, the circumstances are the same.

Concerning the electrical connection of the fluorescent lamp with the board, a positional deviation may be made between the fluorescent lamp and the board and the fluorescent lamp may be given undesired stress in some cases. Therefore, a connecting system will be explained hereinafter in which the fluorescent lamp (especially the glass portion) can be simply connected to the board without generating any stress.

Fig. 10 is a view showing a fluorescent lamp Ia related to the connecting system of another embodiment of the present invention. The fluorescent lamp Ia includes: two flexible lead wires 3a; and a metallic cap 2a having two electrodes 21 connected to the flexible lead wires 3 a. In this connection, in the fluorescent lamp exemplarily shown in the drawing, two electrodes 21a are provided at one end portion. However, it is possible to apply the invention to a cold-cathode tube in which one electrode is provided in each end portion. An insulating portion 22a is provided around the electrode 21a. The present invention is characterized in that a lead wire 3 a extending from the electrode 21a of the metallic cap 2a is utilized for transmitting electrical power to the fluorescent lamp. This structure will be explained in detail as follows.

Each lead wire 3 a is covered with a flexible insulating tube 4a. Due to the above structure, insulation can be ensured between the electrodes. In this embodiment, the electrode itself is not detachably attached to the other terminal. Therefore, it is preferable that the lead wire 3a and the electrode 21a are positively joined to each other by a semipermanent joining means such as brazing, caulking or adhesion. The insulating tube 4a may be attached to the electrode 21a. The lead wire and the insulating tube may be made of various materials. An example of the material of the lead wire is a so-called Dumet wire made of iron-nickel alloy, the surface of which is covered with a copper layer. Concerning the material of the

insulating tube, since the insulating tube must be provided with insulation and heat- resistance, for example, polyimide is preferably used.

In this connection, in the example shown in Fig. 10, the lead wire 3a is connected to the electrode 21a. However, it is possible to adopt a structure in which the lead wire 3 a is not used and a filament (not shown) in the fluorescent lamp Ia is drawn out as it is from the electrode. However, in the structure shown in Fig. 10 in which the lead wire is connected to the electrode, it is possible to prevent an undesired tension from being transmitted to the filament at the time of assembling described later.

Fig. 11 is a view showing a plug connector 5a capable of being connected to the lead wire 3a of the fluorescent lamp Ia shown in Fig. 10. The plug connector 5a includes: a housing 5 Ia made of resin material; and two terminals 52a fixed in the housing 5 Ia by means of press-fitting. The housing 51a includes: an engaging portion (a groove in the example shown in the drawing) 511a engaged with an insulating tube 4a; and latch 512a engaged with a socket connector described later. On the other hand, the terminal 52a includes : a joining portion 521a made of conductive material such as copper alloy, joined to the lead wire 2a by means of brazing or caulking; and a contacting portion (a rod- shaped portion in the example shown in the drawing) 522a coming into contact with a terminal of the socket connector. The lead wire 3 a and the insulating tube 4a are engaged with a plug connector 5a by the joining portion 521a of the terminal 52a and the groove 511a of the housing 51a.

Fig. 12 is a view showing a socket connector 6a with which the plug connector 5a is engaged. The socket connector 6a includes: a housing 61a made of resin material; and two terminals 62a fixed in the housing 61a by means of press-fitting. The housing 61a includes: a portion (a protruding portion in the drawing) 61 Ia for holding the insulating tube 4a in cooperation with the groove 511a of the plug connector 5 a; and a latch engaging portion 612a engaged with the latch 512a of the plug connector 5 a. On the other hand, the terminal 62a includes: a contacting portion (a portion capable of holding the rod-shaped portion 522a in the example shown in the drawing) 621 made of conductive material such as copper alloy and coming into contact with the contacting portion 522a of the terminal 52a of the plug connector 5a; and a tail portion 622a electrically connected to the board 7a described later.

Fig. 13 is an exploded perspective view showing a connecting system in which the

fluorescent lamp Ia is electrically connected to the board 7a by using the plug connector 5a and the socket connector 6a. Fig. 13 shows an example in which parts are not arranged on an upper face 71a of the board 7a. In this case, the socket connector 6a is arranged on a lower face 72a of the board 7a. In the case where the fluorescent lamp is used for a back light device, in order to enhance the illumination performance, a reflecting member is arranged on an upper face (a side on which the fluorescent lamp is arranged) of the board in some cases. Therefore, it is not preferable that other parts are arranged on the upper face. In this case, it is very advantageous that the socket connector 6a can be easily arranged on the lower face 72a. However, if no restrictions are placed, of course, it is possible to arrange the socket connector 6a on the upper face 71a.

On the upper face 71a of the board 7a, support columns 73 a for suppressing heat conduction from the fluorescent lamp to the board are vertically arranged. On the support columns 73a, a lamp holder 8a is attached. The lamp holder 8a includes: a groove 81a capable of receiving the metallic cap 2a of the fluorescent lamp Ia; and an opening portion 82a into which the plug connector 5 a connected to the fluorescent lamp Ia can be inserted.

When a cover 9a, the configuration of which agrees with that of this lamp holder 8a, for holding the fluorescent lamp Ia in cooperation with the lamp holder 8a is engaged with the lamp holder, the fluorescent lamp Ia can be properly fixed.

Fig. 14 is a view showing a state in which the connecting system shown in Fig. 13 has been assembled. Since the lamp holder 8a and the cover 9a cooperate with each other and hold the metallic cap 2a of the fluorescent lamp Ia, the fluorescent lamp can be held at a predetermined position without damaging the glass portion of the fluorescent lamp. Arranging the lamp holder 8a on the board 7a, locating the fluorescent lamp Ia in the holder 8a and engaging the cover 9a with the holder 8a are substantially restricted in the vertical direction (the direction perpendicular to the upper face of the board). Therefore, the working property is excellent. Even when parts can not be arranged on the upper face 71a of the board 7a, the plug connector 5 a can easily make access to the socket connector 6a arranged in the lower face 72a.

In general, in the structure shown in Fig. 13, the lamp holder 8a is fixed by screws, which are inserted from the lower face 72a side of the board 7a, together with the support columns 73a. Therefore, the positioning accuracy of the lamp holder 8a with respect to the board 7a is not so high. Sometimes, the lamp holder 8a considerably deviates from a

predetermined position. However, in the present invention, electric power can be supplied to the fluorescent lamp Ia when the plug connector 5 a connected to the flexible lead wire 3 a is connected to the socket connector 6a. Therefore, positional deviation between the lamp holder 8a and the socket connector 6a can be easily absorbed. Accordingly, there is no possibility that stress is given to the fluorescent lamp by the positional deviation at the time of installing the fluorescent lamp. Therefore, it is unnecessary to pay attention to the positional accuracy. An arranging position of the socket connector 6a can be arbitrarily decided according to the length of the lead wire 3 a (the insulating tube 4a).

Concerning the insulating tube 4a for covering the lead wire 3 a, one end portion of the insulating tube 4a is attached to the electrode 21a of the fluorescent lamp Ia and the other end portion is engaged with the groove 511a of the plug connector 5 a. Due to the foregoing, it is possible to reduce stress given to the electrode 21a when the plug connector 5 a is operated. Concerning the lead wire 3 a, after the lead wire 3 a has been joined to the electrode 21a, it is utilized as a power feeding line without being cut off. Therefore, it is possible to compose an effective system capable of avoiding waste.

Fig. 15 is a view showing an example in which the connecting system shown in Figs. 13 and 14 is applied to the use of a back light. A plurality of fluorescent lamps Ia are arranged in a row. Each fluorescent lamps Ia is electrically connected to the board 7a by the plug connector 5a and the socket connector 6a. In the example shown in the drawing, a lamp holder 8b, in which the above lamp holder 8a is formed into an array shape, is fixed to a support column 73b, which is the same as the above support column 73 a, by means of screwing and the fluorescent lamp Ia is held by a cover 9b in which the above cover 9a is formed into an array shape. Usually, a positional deviation between the lamp holder 8b and the socket connector 6a arranged on the board 7b is relatively large. However, according to the present invention, due to the above structure in which the lead wire and the insulating tube are provided, the above positional deviation can be sufficiently absorbed. When the lamp holder 8a and the cover 9a are integrated with each other into one body or when the lamp holder 8b and the cover 9b are integrated with each other into one body, the number of parts can be reduced.