CONNECTOR FOR CCFL, CIRCUIT BOARD INCLUDING THE CONNECTOR AND METHOD FOR MOUNTING CCFL ON THE BOARD

The present application claims priority from Japanese Patent Application No. 2005-286620, filed on September 30, 2005, the entire content of which is fully incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a connector for connecting a cold cathode fluorescent lamp (hereinafter referred as "CCFL") used for a backlight unit of a liquid crystal display, a circuit board including the connector and a method for mounting the CCFL to the circuit board.

BACKGROUND

A CCFL may be used as a backlight of a liquid crystal display (LCD) or an edge light for illuminating a LCD from the side of the LCD. In order to supply the power to the CCFL, it is conventional to connect a feeder line to each lead terminal at each end of the CCFL. For example, Japanese Unexamined Patent Publication (Kokai) No. 2002-124308 ("Kokai 2002-124308") discloses a structure for connecting a feeder line having a metal fitting to each lead terminal of a CCFL. In this structure, the metal fitting having a through hole is crimped and fixed to the end of each of two feeder lines, and each lead terminal of the CCFL is inserted into the through hole and soldered, whereby the work efficiency may be raised.

Generally, a soldering process is labor-intensive and not easily automated. In addition, components connected by soldering may be less well electrically connected than the external appearance of the solder joint would indicate due to a defect known as "potato soldering" which yields a hollow solder joint that is prone to mechanical and electrical failure due to mechanical shock or vibration. In this connection, Japanese Unexamined Patent Publication (Kokai) No. 2001-43715 ("Kokai 2001-43715") discloses a flat display device including a lamp holder with a contact which is electrically connected, by press- fitting, to a dumet line at each end of a CCFL. In this device, soldering is unnecessary for directly connecting the feeder line to the CCFL. Also, Japanese Unexamined Patent Publication (Kokai) No. 2004-259645 ("Kokai 2004-259645") discloses a connecting

terminal for electrically connecting a dumet line of a CCFL to a feeder line without soldering. By using this connecting terminal, the dumet line may be easily aligned with a contact of the feeder line and press-fitted to the contact, whereby assembling of the CCFL may be automated. The structure described in Kokai 2002-124308 is often used because the structure has a high degree-of-freedom in relation to positioning of the CCFL. However, the operation using the structure may cause the above "potato soldering" and is not easily automated. Further, when the CCFL is exchanged, it is necessary to exchange a whole set including the CCFL, the feeder line and a connector for connecting them. It is costly. On the other hand, in the device described in Kokai 2001-43715, although soldering for connecting the CCFL to the feeder line is not necessary, the lamp holder for holding the CCFL is connected to a power supply by a feeder line. In other words, as a whole display device, a feeder line is used as necessary. Therefore, the soldering process is also necessary and assembling of the whole device is not easily automated. The connecting terminal described in Kokai 2004-259645 has a contact contacting the CCFL and the feeder line extends from the contact. In case that the contact has a shape as shown in Fig. 5 of Kokai 2004-259645, a surface of the contact may be damaged by the edge of a bar-shaped lead terminal of the CCFL when the lead terminal comes into contact with the contact. When assembling of the CCFL is to be automated, the direction of access or movement of a manipulator or the like is preferably limited to the direction perpendicular to a circuit board such as an inverter circuit board on which the CCFL is mounted. This is because the motion and the constitution of the manipulator may be simplified and the possibility of interference between the manipulator and other equipments may be reduced. However, as the CCFL described in Kokai 2004-259645 is moved along its longitudinal direction, it is considered that the CCFL is moved parallel to the circuit board. Therefore, a manipulator having a relatively complicated constitution may be required for automation.

Also, the accuracy of attachment of the terminals on both ends of the CCFL in relation to the longitudinal axis of the CCFL is generally low. Therefore, when the CCFL is held by a fixed lamp holder, as described in Kokai 2001-43715, a disadvantageous stress may be applied to the CCFL and may damage the CCFL, especially when the length of the CCFL is equal to or longer than about one meter.

SUMMARY

An object of at least one embodiment of the present invention is to provide a connector for electrically connecting the CCFL to the circuit board without using the feeder line and soldering, whereby the assembling of the CCFL may be easily automated. Another object of at least one embodiment of the invention is to provide a circuit board including the mounted CCFL and a method for mounting the CCFL on the circuit board. Further, another object of at least one embodiment of the invention is to provide a connector capable of absorbing the dimensional error of the CCFL and/or the positioning error of the lamp holder, even when the accuracies of the dimension of the CCFL and/or the positioning of the lamp holder are not so high.

One embodiment of the invention presents a connector for electrically connecting a cold cathode fluorescent lamp, having a cylindrical body and a lead terminal at each end of the body, to a circuit board, the connector comprising: a socket case configured to be positioned on the circuit board and to contain each end of the lamp; a socket terminal contained in the socket case and having a first contacting portion for gripping the lead terminal of the lamp and a second contacting portion configured to project from the socket case when the socket terminal is contained in the socket case; and a socket cover configured to engage with the socket case and to press the lead terminal of the lamp when the socket cover engages with the socket case such that the first contacting portion of the socket terminal grips the lead terminal.

Another embodiment of the invention presents a connector for electrically connecting a cold cathode fluorescent lamp, having a cylindrical body and a lead terminal at each end of the body, to a circuit board, the connector comprising: a socket case configured to contain each end of the lamp; a socket terminal contained in the socket case and having a first contacting portion for gripping the lead terminal of the lamp and a second contacting portion configured to project from the socket case when the socket terminal is contained in the socket case; a socket cover configured to engage with the socket case and to press the lead terminal of the lamp when the socket cover engages with the socket case such that the first contacting portion of the socket terminal grips the lead terminal; and a circuit board connecting part including a housing capable of engaging with the socket case and a connecting terminal contained in the housing configured to be electrically connected to the circuit board and to grip the second contacting portion of the

socket terminal when the housing engages with the socket case.

Another embodiment of the invention presents a mounting method for electrically connecting a cold cathode fluorescent lamp, having a cylindrical body and lead terminal at each end of the body, to a circuit board, the method comprising steps of: preparing a circuit board on which a socket case configured to contain each end of the lamp is positioned; positioning a socket terminal having a first contacting portion and a second contacting portion in the socket case such that the second contacting portion projects from the socket case and electrically connects the circuit board when the socket terminal is contained in the socket case; positioning the cold cathode fluorescent lamp in the socket case; engaging a socket cover, having a lead terminal pressing portion, with the socket case such that the lead terminal is pressed by the lead terminal pressing portion and gripped by the first contacting portion of the socket terminal.

Yet another embodiment of the invention presents a mounting method for electrically connecting a cold cathode fluorescent lamp, having a cylindrical body and lead terminal at each end of the body, to a circuit board, the method comprising steps of: preparing a circuit board on which a circuit board connecting part having a connecting terminal is positioned such that the connecting terminal is electrically connected to the circuit board; engaging a socket case configured to contain each end of the lamp with the circuit board connecting member; positioning a socket terminal, having a first contacting portion and a second contacting portion, in the socket case such that the second contacting portion projects from the socket case and electrically connects the connecting terminal of the circuit board connecting part when the socket terminal is contained in the socket case; positioning the cold cathode fluorescent lamp in the socket case; engaging a socket cover, having a lead terminal pressing portion, with the socket case such that the lead terminal is pressed by the lead terminal pressing portion and gripped by the first contacting portion of the socket terminal.

Due to the connector for the CCFL of the present invention, the CCFL may be surely connected to the circuit board without using the feeder line and soldering. Further, by using the circuit board connecting part having the housing and/or the elastic socket terminal, a dimensional error or a positioning error of each component may be corrected in all directions. In the mounting method of the invention, the major directions of operations may be generally perpendicular to the circuit board, whereby the mounting or assembling

of the CCFL may be easily automated.

The present invention is described immediately below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS [Fig. 1] An exploded perspective view of a connector according to a first embodiment of the present invention.

[Fig. 2a] A perspective view of a socket case of the connector depicted in Fig. 1. [Fig. 2b] A perspective view showing an aspect other than that of Fig. 2a. [Fig. 3] A perspective view showing the detail of a socket cover of the connector depicted in Fig. 1.

[Fig. 4] A perspective view showing the detail of a socket terminal of the connector depicted in Fig. 1. [Fig. 5] A view for explaining a method for mounting a CCFL using the connector depicted in Fig. 1. [Fig. 6] An exploded perspective view of a connector according to a second embodiment of the present invention. [Fig. 7] A perspective view showing a circuit board connecting member used for the second embodiment.

[Fig. 8] A view for explaining a method for mounting a CCFL using the connector and the connecting part depicted in Fig. 6.

[Fig. 9] A cross-sectional view along 9-9 line of Fig. 8.

[Fig. 10] A cross-sectional view along 10-10 line of Fig. 8.

[Fig. 11] A perspective view of a socket case of a connector according to a third embodiment of the invention. [Fig. 12] A perspective view of a socket terminal of the connector of the third embodiment. [Fig. 13] A perspective view showing the state in which the socket terminal and the CCFL are located in the socket case.

[Fig. 14] A cross-sectional view along 14-14 line of Fig. 13. [Fig. 15] A perspective view of a socket terminal according to a modification of the socket terminal of Fig. 12.

[Fig. 16] A perspective view of a connector according to a fourth embodiment of the invention. [Fig. 17] A perspective view of a circuit board connecting part of the connector of Fig. 16, viewed from the lower side [Fig. 18] A cross-sectional view along 18-18 line of Fig. 16.

DETAILED DESCRIPTION

Fig. 1 is an exploded perspective view of a connector and a CCFL of a first embodiment of the invention. The connector of the first embodiment includes a socket 2 for electrically connecting a CCFL 1 to a main circuit board described below. The socket 2 has a socket case 21 configured to contain each end of a body or a glass tube 11 of the CCFL near the each end thereof, a socket cover 22 configured to engage with the socket case and to position the CCFL 1 in place when assembling, and a socket terminal 23 configured to contact a generally bar-shaped lead terminal 12 of the CCFL 1 when assembling. Hereinafter, these three members constituting the socket 2 are described below.

Figs. 2a and 2b are perspective views of the socket case 21 showing an upper side and a bottom side, respectively. As shown in Fig. 2a, the socket case 21 has a glass tube containing section 211 for containing the glass body 11 of the CCFL near the end thereof and a socket terminal containing section 212 for containing the above socket terminal 23. The glass tube containing section 211 has a cushion receiving portion 213 capable of contacting a cushion 13 attached to the glass body 11 near each end of the body when mounting or assembling the CCFL. The cushion 13 is made from the material having a suitable flexibility such as a sponge or an elastomer. On the bottom of the socket terminal containing section 212, as shown in Fig. 2b, a through hole 214 is formed such that a second contacting portion of the socket terminal 23 described below extends through the hole 214 when assembling. Lead terminal receiving portions 2151 and 2152 are formed at the ends of the socket terminal containing section in relation to the longitudinal direction of the CCFL 1. The lead terminal receiving portions 215a and 215b contact the lead terminal 12 of the CCFL 1 when assembling. Further, on both sides of the socket case 21, latch holes 216 capable of engaging with a latch 224 of the socket cover 22 are formed, whereby the accuracy of assembling of the connector may be raised. The socket case 21

may have leg portions 217 having a suitable shape at the bottom of the case, whereby soldering the socket case 21 to the circuit board may be easily carried out. In addition, as this soldering may be done in a process not included in a mounting or assembling process of the CCFL, the automation of the mounting of the CCFL is not affected. Fig. 3 is a perspective view of the socket cover 22. Different from Fig. 1, the side of the socket cover opposing the CCFL 1 when assembling is directed upward in Fig. 3. As shown, the socket cover 22 has an operation surface 221 (see Fig. 1) pressed by an operator or a manipulator when assembling, a cushion pressing portion 222 for pressing a cushion 13 of the CCFL 1, two lead terminal pressing portions 2231 and 2232 for positioning and pressing the lead terminal 12 of the CCFL 1 and a latches 224 configured to engage with the latch holes 216 of the socket case 21. The socket cover 22 is preferably made from a transparent resin such as a polycarbonate such that the inside of the socket case may be monitored after assembling.

Fig. 4 is a perspective view of the socket terminal 23. The socket teπninal 23 has first contacting portions 2311 and 2312 configured to cooperate for gripping the lead terminal 12 of the CCFL 1 when assembling, elastically supporting portions 2321 and 2322 for elastically supporting the first contacting portions 2311 and 2312, respectively, a base portion 233 connected to both of the supporting portions 2321 and 2322 and a second contacting portion 234 straightly extending from the base portion 233. The first contacting portions 2311 and 2312 define a first opening 235 having a width dl longer than the diameter of the lead terminal 12 of the CCFL 1 and a second opening 236 having a width d2 shorter than the diameter of the lead terminal 12. The elasticity of the two supporting portions may be determined corresponding to the kind or the dimension of the CCFL. For example, when the typical CCFL, including the glass tube 11 having the diameter of about 6mm and the length of about 500mm and the lead terminal having the diameter of about 0.3mm to 0.6mm, is used, the first contacting portions are preferably configured to grip the lead terminal 12 with a gripping force of about 2N.

In other words, the above socket terminal 23 has a pair of cantilever-type contacting portions opposing each other. However, the contacting portions 2311 and 2312 and the elastically supporting portions 2321 and 2322 may be replaced with a so-called press-fitting type member having, for example, a U-shaped opening. The socket terminal 23 is preferably made from the conductive material such as a copper alloy, capable of

being elastically deformed to some extent.

Next, a mounting method of the CCFL 1 using the socket case 21, the socket cover 22 and the socket terminal 23 is described, with reference to Figs. 1 and 5. First, a main circuit board 4, such as an inverter board used for a backlight unit of a liquid crystal display, is prepared. On the circuit board 4, some socket cases 21 are positioned in place, indicated by a portion A of Fig. 5. The number of the socket cases 21 corresponds to the number of the CCFL to be mounted. The socket cases may be easily positioned on the circuit board 4 by soldering the leg portions 217 of the socket cases to the board. Then, the socket terminals 23 are contained in the socket terminal containing sections 212 of the socket cases 21, as shown in Fig. 1. At this point, the second contacting portion 234 of each socket terminal extends through the hole 214 of the socket case and a through hole (not shown) formed on the circuit board 4. Therefore, the socket terminal 23 may be electrically connected to the main circuit board 4. Alternatively, the second contacting portion 234 may be formed as a so-called surface-mount type and electrically connected to the circuit board without forming a through hole on the circuit board.

Next, as indicated by a portion B of Fig. 5, the glass body 11 of each CCFL 1 is contained in the glass body containing section 211 of each socket case 21. In this state, each CCFL 1 is merely put on the socket case, therefore, the lead terminal 12 of each CCFL 1 is positioned at the first opening 235 of each socket terminal 23. Then, the socket cover 22 as shown in Fig. 3 is positioned such that the cushion pressing portion 222 of the socket cover 22 contacts the cushion 13 of the CCFL 1 and the lead terminal pressing portion 2231 and 2232 contact the lead terminal 12 of the CCFL 1, as indicated by a portion C of Fig. 5. Further, by downwardly pushing the operation surface 221 of the socket cover 22, the assembling of the CCFL 1 is completed, as indicated by a portion D of Fig. 5. In this state, the lead terminal 12 of the CCFL 1 is pushed into the second opening 236 of the socket terminal 23 and surely electrically connected to the first contacting portions 2311 and 2312. Further, the cushion 13 contacts both the cushion receiving portion 213 of the socket case 21 and the cushion pressing portion 222 of the socket cover 22, whereby the CCFL 1 may be positioned at a desired position. At this point, by pressing two sites of the lead terminal 12 opposing each other in relation to a site contacting the first contacting portions of the socket terminal 23 by using the two pressing portions 2231 and 2232 of the socket cover 22, the orientation of the CCFL 1 when

assembling may be stable and the CCFL may be surely connected to the socket terminal 23. Further, when a length Ll (see Fig.2a) of the cushion receiving portion 213 along the longitudinal direction of the CCFL is longer than a length L2 (see Fig. 1) of the cushion 13, the dimensional or positioning error of the CCFL may be absorbed to some extent. As described above, the electrical connection between the CCFL 1 and the circuit board 4 may be completed at the same time when the CCFL 1 and the socket 2 are mounted on the circuit board 4. Therefore, a feeder line for supplying power to the CCFL is unnecessary. As apparent from the above, a series of operations including the positioning of the socket terminal into the socket case on the circuit board, the positioning of the CCFL into the socket case and the assembling the CCFL by using the socket cover (i.e., the connecting the CCFL to the socket terminal) may be carried out, from above the circuit board, along only one direction generally perpendicular to the circuit board. Therefore, due to the configuration of the invention, the mounting of the CCFL using a manipulator or the like may be remarkably easily automated. Further, the lead terminal of the CCFL has a generally cylindrical shape and the side of the cylindrical shape (having a generally smooth surface) contacts the first contacting portion of the socket terminal, the socket terminal is not damaged by the edge of the lead terminal. Also, as the first contacting portion has a smooth surface, the lead terminal is not damaged. Therefore, a life of each element may be extended. Next, a connector according to a second embodiment of the invention is described.

Fig. 6 shows an exploded perspective view of the connector of the second embodiment. The second embodiment is different from the first embodiment in that a circuit board connecting part 3 a is arranged under a socket 2a. In the second embodiment, therefore, the socket 2a is not directly connected to the circuit board and has a socket case 21a with a connector cover 218a capable of engaging with the circuit board connecting part 3a. The connecting part 3a engaged with the connector cover 218a is connected to the circuit board. As the other points of the second embodiment may be the same as those of the first embodiment, only matters regarding the circuit board 3a are described below and the other description is omitted. As shown in Fig. 6, the circuit board connecting part 3a is constituted by a housing

31a capable of engaging or fitted with the connector cover 218a of the socket case 21a and a connecting terminal 32a contained in the housing 31a and electrically connecting the

socket terminal 23 when assembling. The connecting terminal 32a has a third contacting portion 321a configured to electrically contact the second contacting portion 234 of the socket terminal 23 when assembling, a base portion 322a for supporting the third contacting portion 321a and mount portions 323a extending from the base portion 322a along the direction opposite to the third contacting portion 321a for electrically contacting the circuit board. Although three mount portions 323 a are illustrated in Fig. 6, the connecting terminal may have only one mount portion. Similarly to the socket terminal 23, the connecting terminal 32a is preferably made from the conductive material such as a copper alloy, capable of being elastically deformed to some extent. In addition, although the connecting terminal is illustrated as a surface-mount type, the connecting terminal may be configured as a through-hole type such as the socket terminal 23. In this case, a through hole for the connecting terminal is formed on the circuit board.

Next, a mounting method of the CCFL 1, using the above socket case 21a and the connecting part 3 a, and using the socket cover 22 and the socket terminal 23 similar to the first embodiment, is described. First, as shown in Fig. 7, the connecting terminal 32a is contained in the housing 31a so as to form the connecting part 3 a. The housing 31a has a through hole 311a through which the second contacting portion 234 of the socket terminal 23 may extend when assembling.

Then, a main circuit board 4a such as an inverter board is prepared. On the circuit board 4a, some connecting parts 3 a as shown in Fig. 7 are positioned in place, indicated by a portion A of Fig. 8. At this point, the mount portions 323a of the connecting terminal 32a are connected to the circuit board 4a at predetermined positions such that the connecting terminal 32a is electrically connected to the circuit board 4a. Next, as indicated by a portion B of Fig. 8, each assembly including the CCFL 1 and the socket 2a (or the socket case 21a, the socket terminal 23 and the socket cover 22) is positioned on each circuit board connecting part 3a. Next, as indicated by a portion C, each assembly is downwardly moved so as to fit the housing 31a of the connecting part 3a into the connector cover 218a of the socket case 21a, whereby the mounting is completed. Instead of mounting the assembly on the circuit board connecting part 3a, as shown in Fig. 5, it is obviously possible to arrange the socket case 21a on the circuit board 3 a, position the socket terminal 23 and the CCFL 1 into the socket case 21a and, then, fit the socket cover 22 into the socket case 21a.

Fig. 9 is a cross-sectional view along 9-9 line of Fig. 8. As shown, when the mounting of the assembly is completed, the second contacting portion 234 of the socket terminal 23 extends through the hole 31 Ia of the housing 31a of the circuit board connecting part 3a and contacts the third contacting portion 321a of the connecting terminal 32a. Although the configuration of the contact between the second and third contacting portions may be suitably selected, the illustrated configuration, in which the third contacting portion 321a having a pair of cantilever-type contacting portions grips the second contacting portion 234, is preferable. Due to this configuration, the electrical connection between the CCFL 1 and the circuit board 4a may be completed at the same time when the CCFL 1, the socket 2a and the circuit board connecting part 3a are mounted on the circuit board 4a. Apparently, a series of major operations may be carried out, from the above the circuit board, along only one direction generally perpendicular to the circuit board.

As described above, the difference between the first and second embodiments is whether the circuit board connecting part is used or not. The necessity of the connecting part is determined by, for example, whether the socket case has a sufficient heat resistance against the heat generated when the socket case is soldered to the circuit board (generally, the socket case is heated to about 260 - 270 ⁰ C). Therefore, when the socket case has a low heat resistance, the connecting part having the housing with a high heat resistance may be used.

In the first embodiment, the dimensional or positioning error of the CCFL along the longitudinal direction of the CCFL may be absorbed to some extent, as describe above. In the second embodiment, however, the dimensional or positioning error in any direction may be absorbed. Concretely, in the second embodiment, the error along the longitudinal direction of the CCFL may be absorbed by the socket case 21a including the cushion receiving portion having the same constitution as that of the socket case 21 of the first embodiment. Also, the error along the direction perpendicular to both the circuit board and the longitudinal direction of the CCFL (i.e., the direction N depicted in Fig. 9) may be absorbed by the second contacting portion 234 of the socket terminal 23 and the third contacting portion 321a of the connecting terminal 32a which are configured to slide relative to each other. Further, the positioning error of the connecting part 3 a on the circuit board, along the direction M (depicted in Fig. 10 showing a cross section along 10-

10 line of Fig. 8) perpendicular to both the direction N and the longitudinal direction of the CCFL, may be absorbed by a gap 33a formed between the inner surface of the connector cover 218a of the socket case 21a and the outer surface of the housing 31a of the connecting part 3a. Due to this gap, the socket case 21a may be displaced to some extent relative to the housing 31a. Obviously, as the gap 33a may be formed such that the CCFL may be displaced along the longitudinal direction of the CCFL, the dimensional or positioning tolerance of the CCFL along the longitudinal direction of the CCFL may be further increased.

In the second embodiment, the dimensional or positioning error may be absorbed to some extent. However, when the length of the CCFL is equal to or longer than one meter, it may be required to absorb the larger error. For example, the case, in which the dimensional or positioning error in the direction M in Fig. 10 is larger than the gap 33 a, is relevant. Thus, in another embodiment as described below, a connector capable of absorbing the larger error is explained. Fig. 11 is a perspective view of a socket case 2 Ib of a socket of a connector according to a third embodiment of the invention. The socket case 21b is similar to the socket case 21a of the second embodiment. However, the connector cover 218b of the socket case 21b extends in the vertical direction longer than the connector cover 218a of the socket case 21a. Further, as described below, the shape of a through hole 214b extending through the connector cover 218b is different from the shape of the corresponding through hole 214 of the socket case 21a.

Fig. 12 is a perspective view of a socket terminal 23b of the connector of the third embodiment. The socket terminal 23b is different from the socket terminal 23 of Fig. 4 in that a second contacting portion 234b of the socket terminal 23b is connected to a base portion 233b via an elastic connecting portion 237b extending from the lateral side of the base portion 233b. Further, the whole length of the second contacting portion 234b extends longer than the second contacting portion 234 of the socket terminal 23, corresponding to the length of the connector cover 218b of the socket case 21b.

Fig. 13 is a perspective view showing the state in which the socket terminal 23b and the CCFL 1 are located in the socket case 21b, and Fig. 14 is a cross-sectional view along 14-14 line of Fig. 13. As shown in Fig. 11, the through hole 214b through which the second contacting portion 234b of the socket terminal 23b extends has an elongated inlet

2141b having the length L3 along the direction M perpendicular to both the longitudinal direction of the CCFL and the vertical direction. As shown in Fig. 14, the length of the through hole 214b along the direction M is gradually reduced toward the bottom. Further, an outlet 2142b of the through hole 214b is configured such that a fulcrum portion or a connection 238b between the second contacting portion 234b and the elastic connecting 237b may be pressed into the outlet 2142b. As the socket terminal 23b is also made from the conductive elastic material such as a copper alloy, the base portion 233b of the socket terminal 23b positioned in the socket case 21b may be displaced about the fulcrum 238b generally in the direction M within the length of L3 of the inlet 2141b of the through hole 214b. Therefore, the CCFL 1 connected to the socket terminal 23b may be displaced in the direction M wider than in the second embodiment, whereby the considerably large dimensional of the CCFL or the positioning error of the connector may be absorbed.

Due to the combination of the position of the fulcrum 238b and the dimension (i.e., the width and the thickness) of the elastic connecting portion 237b, the elastic force of the socket terminal may be arbitrary adjusted. In addition, the width of the elastic connecting portion 237b is preferably parallel to the longitudinal direction of the CCFL, whereby the base portion 233b maybe displaced in the direction M as well as restraining a reactive force applied to the CCFL.

In order to allow the above displacement of the socket terminal, a glass tube containing section 211b and a lead terminal receiving portion 2151 b of the socket case 21 b have somewhat wide lengths in the direction M, as shown in Fig. 11. Further, in order to smooth the displacement of the base portion 233b about the fulcrum 238b, the socket case

21b preferably has a recessed section 219b near the inlet 2141b of the through hole 214b.

Fig. 15 is a perspective view of a socket terminal 23b' which is a preferred modification of the socket terminal 23b. The socket terminal 23b' is different from the socket terminal 23b in that a second contacting portion 234b' and an elastic connecting portion 237b' thereof have shapes meandering in the direction P generally perpendicular to the direction M. Due to this, a base portion 233b' of the socket terminal 23b ¹ may be displaced also in the direction P to some extent. In addition, the position of a fulcrum 238b' may be arbitrary changed between the base portion 233b' and the second contacting portion 234b', depending on the supposed dimensional or positioning error of the CCFL. For example, as shown in Fig. 15, the fulcrum 238b' is positioned at an upper part (or near

the base portion 233b') in the socket terminal 23b', in comparison with the fulcrum 238b of Fig. 12. In this configuration, although the length of the displacement of the base portion 233b' in the direction M becomes relatively short, the state of the gripped CCFL may be stable. Therefore, this configuration is suitable for the case in which dimensional or positioning error is relatively small.

As shown in Fig. 13, the socket 2b has a socket cover 22b provided with the similar constitution and function as the socket cover 22 of the first embodiment. The socket cover 22b may be engaged with the socket case 21b by vertically and downwardly moving the cover 22b toward the socket case 21b. Alternatively, as shown in Fig. 13, the socket cover 22b may be pivotally attached to the socket case 21b by means of a hinge 225b.

The third embodiment illustrated in Figs. 11 to 15 may absorb the dimensional or positioning error mainly in the direction M in the socket case. In contrast, in a fourth embodiment as described below, the relatively large error may be absorbed in a circuit board connecting part.

Fig. 16 shows a connector for the CCFL according to a fourth embodiment of the invention. As shown, a socket case 21c is connected to a main circuit board 4c by means of a circuit board connecting part 3c. In this configuration, the connecting part 3c is attached to a lower surface of the circuit board 4c, and a connector cover 218c of the socket case 21c extends through an attachment hole 41c formed on the circuit board 4c and is connected to the board 4c. However, the connecting part 3c may be attached to an upper surface of the circuit board 4c. The feature of the fourth embodiment is an internal constitution of the connecting part 3c, as described below. Therefore, the socket case 21c may be the same as the above socket case 21b. In addition, as shown in Fig. 16, the connector cover 218c may have a proj ection 2181c for supporting a reflecting plate (not shown).

Fig. 17 is a perspective view of the circuit board connecting part 3c viewed from the lower side, and Fig. 18 is a cross-sectional view along 18-18 line of Fig. 16. The circuit board connecting part 3c a fixed housing 31c fixed to the circuit board 4c, a connecting terminal 32c downwardly extending through the socket case 21c and electrically connected to a socket terminal 23c which is preferably similar to the socket terminal 23b, and a movable housing 33c contained in the fixed housing 31c such that the

movable housing 33c may be moved relative to the fixed housing 31c and engaged (or fitted) with the connector cover 218c.

Next, the constitution of the connecting terminal 32c is explained. The connecting terminal 32c is positioned in the movable housing 33c and has a third contacting portion 321c for contacting or electrically connecting to the second contacting portion 234c of the socket terminal 23c when assembling. For example, the third contacting portion 321c is composed of a pair of opposing elastic members. The third contacting portion 321c further has one or more fixed portion 322c fixed to the movable housing 33c by, for example, press fitting, one or more (two in this case) leg portion 323c extending through the housing 31c to the circuit board 4c and preferably having one or more (two in this case) bending portion, and one or more circuit board contacting portion 324c extending through a through hole 42c formed on the circuit board 4c and electrically connected to the board 4c by soldering. Similarly to the above connecting terminal 32, the connecting terminal 32c is made from the conductive material such as a copper alloy, capable of being elastically deformed to some extent. Further, it is preferable that the components 321c - 324c of the connecting terminal 32c are integrally formed.

As shown in Fig. 18, as the leg portions 323c of the connecting terminal 32c may be elastically deformed, the movable housing 33c may be displaced within the fixed housing 31c, mainly in the horizontal direction or the direction M. Therefore, the connector cover 218c fitted with the movable housing 33c may be also displaced in the horizontal direction, whereby the socket 2c holding the CCFL 1 (Fig. 16) may be also displaced relative to the circuit board 4c. Accordingly, the dimensional or positioning error, which is far larger than that of the case of Fig. 9, may be absorbed while the connection between the second contacting portion 234c of the socket terminal 23c and the third contacting portion 321c of the connecting terminal 32c is maintained.

Preferably, the two leg portions 323c of the connecting terminal 32c are symmetrically formed in relation to the third contacting portion 321c such that the movable housing 33c may be horizontally displaced without changing the orientation thereof. Also, the connecting terminal 32c is preferably configured such that the bending stiffness of a bending portion of the connecting terminal outside the movable housing 33c is smaller than that of another bending portion of the connecting terminal inside the movable housing 33 c. Such a configuration may be realized by narrowing the width of the

bending portion of the connecting terminal outside the movable housing relative to that of the other bending portion insides the movable housing, due to this configuration, an excessive stress is not applied to a portion of the connecting terminal 32c attached to the movable housing 33c. Therefore, the dimensional or positioning error may be absorbed while the connection between the second contacting portion 234c of the socket terminal 23c and the third contacting portion 321c of the connecting terminal 32c is maintained.

Although the movable housing 33c is not an indispensable component, the movable housing may function as a guide member for guiding the connector cover 218c such that the connector cover is inserted into the circuit board connecting part 3 c from the above while maintaining the correct position and the orientation of the connector cover.

Accordingly, the second contacting portion 234c of the socket terminal 23c may be surely connected to the third contacting portion 321c of the connecting terminal 32c.

While the invention has been described with reference to specific embodiments chosen for the purpose of illustration, it should be apparent that numerous modifications could be made thereto, by one skilled in the art, without departing from the basic concept and scope of the invention.