Patent Application
20110194032
1. Field of the Invention
The present invention relates to a lighting device for a display device, a display device and a television receiver.
2. Description of the Related Art
A liquid crystal display device used in a television receiver typically includes a liquid crystal panel and a backlight arranged on the backside of the liquid crystal panel. One of the known backlights includes lamps (or light sources) such as cold cathode tubes, a chassis arranged to contain the lamps, and an inverter arranged to drive the lamps (as shown in JP-A-2006-351527, for example).
In the backlight disclosed in JP-A-2006-351527, terminals for connecting the lamps with the inverter are mounted to the chassis, so that power can be supplied for the lamps fitted to the terminals. In this case, each lamp should have external electrodes at respective ends, and the external electrodes can be attached to the lamp as follows.
Cylindrical ferrules for a lamp are prepared as external electrodes, for example, and the assembly can be completed by fitting the lamp into the external electrodes. In this case, the ferrules should have an inner diameter corresponding to the outer diameter of the lamp. That is, different ferrules should be provided to correspond one-to-one with different shapes of lamps. Further, the outer shapes (or outer diameters) of the ferrules should be varied to correspond one-to-one with different shapes of the above terminals. Accordingly, different ferrules should be fitted to lamps of different types of television receivers, if the outer diameters of the lamps vary depending on the types of television receivers, for example. Preparing different ferrules for different outer diameters of lamps requires a lot of time and effort, and may cause reduction in manufacturing efficiency, which can lead to increase in cost. Further, ferrules unconformable to the outer diameter may be incorrectly mounted to lamps and thereby cause defects, which can lead to reduction in yield rate.
In view of the foregoing circumstances, preferred embodiments of the present invention provide a highly-reliable lighting device for a display device, in which common ferrules capable of being used for any shape of lamps (or tubular light sources) are provided as ferrules used to supply power for lamps, in order to improve the manufacturing efficiency and prevent increases in cost. In addition, preferred embodiments of the present invention provide a highly-reliable display device and a television receiver.
A lighting device for a display device, according to a preferred embodiment of the present invention, includes a tubular light source, and a terminal arranged to supply power to the tubular light source. The tubular light source includes a glass tube, and a ferrule having a cylindrical shape capable of being fitted to the glass tube. The ferrule is arranged to electrically connect the tubular light source to the terminal. The ferrule includes an inner-diameter-changing elastic member capable of elastic and radial deformation, so that the inner diameter thereof is variable according to the outer diameter of the glass tube.
In the present lighting device for a display device, the tubular light source includes a glass tube and a ferrule, while the ferrule includes an inner-diameter-changing elastic member so that the inner diameter thereof is variable depending on the outer diameter of the glass tube. According to the above-described construction, even if the outer diameter of the glass tube is changed due to a design change for varying the brightness of the tubular light source according to the type of a display device using the present lighting device, for example, the same ferrule as that having been used before the design change can be used as a common ferrule. For example, the same ferrule can be used as a common ferrule for a glass tube having a tube diameter of about 3 mm and a glass tube having a tube diameter of about 4 mm, without the need for preparing separate ferrules differing in inner diameter. The ferrule as a common ferrule can be used to provide electrical connection with the terminal, which enables reliable power supply for the tubular light source. Consequently, the present lighting device can be provided as a highly-reliable lighting device for a display device. The common ferrule can lead to a reduction in the number of types of ferrules to be manufactured, resulting in improvement of manufacturing efficiency. Further, defects, which may be caused by mounting a ferrule that does not conform or fit to the outer diameter of a lamp, can be reliably prevented. Thereby, the reliability and the manufacturing yield can be improved.
Other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.
Preferred embodiments of the present invention will be hereinafter explained with reference to the drawings. The explanation will be made for a liquid crystal display device including a lighting device for a display device according to a preferred embodiment of the present invention as a backlight, and further for a television receiver including the liquid crystal display device.
The television receiver TV shown in
The liquid crystal display device D preferably has a horizontally-elongated rectangular shape as a whole, and includes a liquid crystal panel 11 as a display panel and the lighting device 10 as an external light source for the liquid crystal panel 11, which are covered with a bezel 9 on the front side (or display surface side) and thereby are held in an assembled state, as shown in
The liquid crystal panel 11 has a well-known construction, in which the gap between a pair of glass substrates is filled with liquid crystal as a material with an optical property that changes with applied voltage. TFTs (Thin Film Transistors), as switching elements connected to source wiring lines and gate wiring lines extending at right angles to each other, are provided on the TFT substrate or one of the pair of glass substrates, while a color filter having color sections of three primary colors, i.e., Red (R), Green (G) and Blue (B), arranged in a matrix is provided on the CF substrate.
The lighting device 10 includes a lamp unit 12 and power boards (or inverter boards) 16. The lamp unit 12 includes a metallic chassis 13 preferably defined by a horizontally-elongated rectangular plate. The lamp unit further includes a plurality of discharge tubes (or tubular light sources) 15 held in a horizontal position and contained in the chassis 13 so as to be vertically arranged along the front surface of the chassis 13 and parallel or substantially parallel to one another, and a plurality of relay connectors (or terminals) 14 which are vertically arranged along the lateral edges of the chassis 13 so as to correspond to the respective discharge tubes 15. The power boards 16 are disposed on the back side of the chassis 13 so as to supply power to the discharge tubes 15 via the relay connectors 14.
A plurality of mounting holes 13H having a substantially rectangular shape are formed through the chassis 13 so as to extend from the front side to the back side, and are vertically arranged and located to overlap with the ends of the discharge tubes 15 when viewed planarly. The relay connectors 14 are mounted through the respective mounting holes 13H. Note that a view referred to as a planar view in the present preferred embodiment corresponds to a view obtained by seeing the display surface of the liquid crystal display device D from the front side.
Each relay connector 14 includes a holder 20 preferably made of synthetic resin, and a relay terminal (or a connecting member) 31 that is housed in the holder 20 and preferably made of metal such as stainless steel.
The holder 20 includes a box-shaped portion 21 that defines a block-shaped configuration as a whole, and further includes a wall portion 22 that projects backward (or toward the back side of the chassis 13) from the back surface of the box-shaped portion 21.
A container room 23 is provided in the box-shaped portion 21, so as to have an opening extending from the front side to the lateral side (i.e., the lateral side on the opposite side of the lateral edge portion of the chassis 13). The front opening portion of the opening of the container room 23 is provided as a receiving opening (or engaging base portion) 24, into which an end portion (or ferrule 36) of a discharge tube 15 can be fitted from the front side. The lateral opening portion is provided as an escape opening 25 for preventing interference with the glass tube 34 when the end portion (or ferrule 36) of the discharge tube 15 is held in the container room 23. A stopper 26 is provided on the escape opening 25, so as to bulge inward from the opening edge and so as to define a plate-shaped configuration. Due to the stopper 26, the escape opening 25 is narrowed to define a substantially U-shaped opening. The vertical size of the substantially U-shaped escape opening 25 is set to be smaller than the outer diameter of the body 37 of the ferrule 36 and be equal to or slightly larger than the outer diameter of the glass tube 34 of the discharge tube 15. On the escape opening 25, a concave portion 27 having a semicircular shape is formed on the far end portion of the opening edge. The radius of curvature of the concave portion 27 is set to be equal to or slightly larger than the radius of curvature of the outer circumference of the glass tube 34. On the escape opening 25, a pair of upper and lower guiding portions 28 are provided on areas of the opening edge on the front side of the concave portion 27.
On the box-shaped portion 21, an extended portion 29 extending parallel or substantially parallel to the chassis 13 is provided on the lateral surface of the box-shaped portion 21 that includes the escape opening 25. The extended portion 29 extends so as to separate the front surface of the chassis 13 from the escape opening 25.
A pair of upper and lower retaining protrusions 30 are provided on the outer surface (i.e., upper surface and lower surface) of the wall portion 22. The retaining protrusions 30 can prevent the present relay connector 14 from escaping from the chassis 13.
The relay terminal 31 is held within the holder 20. The relay terminal 31 can be formed by bending a metallic plate that is formed into a predetermined shape by punching. The relay terminal 31 includes a pair of vertically symmetrical elastic pressing portions 32 preferably defined by curved plates, and further includes a board connecting portion 33 preferably defined by a flat plate-shaped portion that projects to the back side. The pair of elastic pressing portions 32, which are housed in the container room 23, can deflect elastically and vertically so as to increase distance therebetween. The vertical distance between the pair of elastic pressing portions 32 is shortest at a position corresponding to the front side of the concave portion 27 of the stopper 26. The minimum distance between the elastic pressing portions 32, when the elastic pressing portions 32 are not forced into elastic deflection or are in a free state, is set to be smaller than the outer diameter of the body 37 of the ferrule 36 attached on the discharge tube 15. On the other hand, the board connecting portion 33 projects from the back surface of the box-shaped portion 21 so as to be exposed to the outside of the holder 20, and extends backwards along the wall portion 22.
When the relay connector 14 is mounted to the chassis 13, the wall portion 22 of the holder 20 is inserted into a mounting hole 13H from the front side of the chassis 13. Thereby, the outer surface of the box-shaped portion 21 comes into contact with the opening edge of the mounting hole 13H on the front surface of the chassis 13, while the retaining protrusions 30 are locked by the opening edge of the mounting hole 13H on the back surface of the chassis 13. Thus, the chassis 13 is sandwiched between the outer surface of the box-shaped portion 21 on the front side and the retaining protrusions 30 on the back side. Thereby, the holder 20 is fixed to the chassis 13 so that its movement in the mounting direction (i.e., the through direction of the mounting hole 13H) is restricted. Then, the mounting of the relay connector 14 to the chassis 13 is completed. When the relay connector 14 is attached to the chassis 13, the box-shaped portion 21 as the front end portion of the holder 20 projects (or is exposed) to the front side of the chassis 13 while the wall portion 22 as the back end portion of the holder 20 projects (or is exposed) to the back side of the chassis 13.
Each discharge tube 15 is preferably formed of a cold cathode fluorescent tube that includes a generally elongated straight glass tube 34 having a circular cross section (and having a tube diameter of about 3 mm, for example) . The cold cathode fluorescent tube further includes elongated metallic (e.g., nickel or cobalt metal) outer leads 35, which have a circular cross section and project linearly from the respective ends of the glass tube 34 and coaxially with the glass tube 34. Further included are ferrules 36 attached to the respective end portions of the glass tube 34. Mercury is encapsulated in the glass tube 34. Each end portion of the glass tube 34 is melted into a substantially hemispherical shape by heat, and thereby forms a domed portion. The outer lead 35 penetrates the domed portion.
Each ferrule 36 preferably is a single-piece component having a cylindrical shape, which can be formed by bending or hammering a metallic (e.g., stainless steel) plate that is formed into a predetermined shape by punching. The ferrule 36 includes a body 37 and a conductive portion 40. The body 37 preferably has a cylindrical shape concentric with the glass tube 34. The body 37 is configured so as to change its inner diameter according to the outer diameter of the glass tube 34. Specifically, elastic members 38 (as pairs of elastic members 38A, 38B) defined by leaf-spring portions capable of elastic and radial deformation are provided as inner-diameter-changing elastic members. The outer diameter is set to a fixed value, so as to be capable of being fitted to the receiving opening (or engaging base portion) 24 of a relay connector 14.
The elastic members 38 as inner-diameter-changing elastic members include first elastic members (or first inner-diameter-changing elastic members) 38A and second elastic members (or second inner-diameter-changing elastic members) 38B, which are arranged at the respective axial ends of the ferrule 36. The first elastic members are capable of elastic deformation at the opposite side of the conductive portion 40, while the second elastic members are capable of elastic deformation at the side of the conductive portion 40. That is, as schematically shown in
Referring to
A second elastic member 38B, i.e., the other of the pair of elastic members 38A, 38B, is arranged circumferentially adjacent to the first elastic member 38A, and preferably includes a cantilevered portion extending anteriorly or reversely from the first elastic member 38A (specifically, in an oblique direction slightly leaning radially inwardly), which is capable of elastic and radial deflection with a supported point on its proximal end (or posterior end). The distal end of the second elastic member 38B is provided as a contact point when abutting on the outer circumferential surface of the glass tube 34. The imaginary line that connects the contact points provided on the three second elastic members 38B, 38B, 38B forms a circle concentric with the body 37. The diameter of the imaginary circle, when the second elastic members 38B are not forced into elastic deflection or are in a free state, is preferably smaller than the outer diameter of the glass tube 34.
The first elastic members 38A, 38A, 38A are preferably arranged at even intervals or at intervals of 120°, for example, along the circumferential direction of the ferrule 36. The second elastic members 38B, 38B, 38B are arranged at even intervals or at intervals of 120°, for example, along the circumferential direction of the ferrule 36. The first elastic member 38A and the second elastic member 38B of each pair are circumferentially adjacent to each other. That is, as shown in
The conductive portion 40 is preferably a cantilevered portion that extends anteriorly from the anterior end of the body 37. The conductive portion 40 includes a long portion 41 that is continuous with the anterior end of the body 37, and a cylindrical portion 42 that further projects anteriorly from the anterior end (or distal end) of the long portion 41.
Referring to
The cylindrical portion 42, which can be formed by bending a portion laterally extending from the distal end of the long portion 41 into a cylindrical shape, is arranged substantially coaxially with the body 37. The cylindrical portion 42 is capable of displacement around the axis of the ferrule 36 and radial displacement, due to elastic deflection of the long portion 41.
Next, an assembling process for attaching a ferrule 36 to a glass tube 34 will be explained.
During the assembling process, while a ferrule 36 and a glass tube 34 are held by respective holding devices (not shown), the ferrule 36 and the glass tube 34 are moved relatively and coaxially so as to approach each other. Thereby, the body 37 is fitted onto the glass tube 34. In the course of insertion of the glass tube 34 into the body 37, the tapered surfaces defined by the inclined surfaces 80, 80, 80 of the three first elastic members 38A, 38A, 38A provide guidance for the insertion as shown in
During the insertion of the glass tube 34 into the body 37, the first elastic members 38A undergo elastic deformation while the glass tube 34 contacts the inclined surfaces 80, and the elastic deformation of the first elastic members 38A continues until the outer circumferential surface of the glass tube 34 comes into contact with the curved portions 39 of the first elastic members 38A as a result of further progress in insertion. When the insertion thereafter further proceeds, the glass tube 34 comes into contact with the inner sides of the second elastic members 38B at the other end side. Then, the glass tube is pushed to the other end side while involving elastic deformation of the second elastic members 38B. Consequently, the glass tube 34 is fitted to the body 37 while being caught by the first and second elastic members 38A, 38B, as shown in
When the insertion of the glass tube 34 further proceeds, the tip of the outer lead 35 having passed through the body 37 begins to enter the hollow of the cylindrical portion 42 (See
Thereafter, the cylindrical portion 42 is clamped so as to be deformed due to diameter reduction. After being clamped, the cylindrical portion 42 is electrically conductively fixed to the outer lead 35 by welding, for example, and consequently the ferrule 36 is integrated with the glass tube 34. Then, the assembling process terminates, and the discharge tube 15 is completed.
When the ferrule 36 is attached to the glass tube 34, the body 37 is concentrically held on the glass tube 34 due to the elastic holding function of the elastic members 38A, 38B. A gap (airspace) is secured between the outer circumference of the glass tube 34 and the inner circumference of the body 37, so as to extend over the substantially entire circumference.
The body 37 of the ferrule 36, which is thus capable of holding the glass tube 34 due to the elastic deformation of the elastic members 38A, 38B, can vary in inner diameter depending on the outer diameter of the glass tube 34. As a result of this unique construction, the ferrules 36 can be used as common ferrules for glass tubes 34 differing in outer diameter.
The discharge tube 15, thus assembled, is fixed to relay connectors 14 (See
The discharge tube 15 thus mounted is held by the pairs of elastic pressing members 32 at its end portions, and consequently is fixed to the chassis 13 via the relay terminals 31 and the holders 20 provided as the relay terminal 31 mounting bases. At that time, the weight of the discharge tube 15 is received solely by the chassis 13 via the relay connectors 14. That is, the outer leads 35 will not be under load due to the weight of the discharge tube 15.
The pair of elastic pressing members 32 can have elastic contact with the outer circumferential surface of the body 37, and thereby the outer lead 35 is electrically conductively connected to the relay terminal 31 via the ferrule 36. Further, the glass tube 34 is held due to elastic restoring forces of the pair of elastic pressing members 32, so as to be pressed against the concave portion 27 of the stopper 26. Therefore, when viewed along the axial direction of the discharge tube 15, the body 37 appears to be positioned so as to partially overlap with the stopper 26. That is, the end edge of the body 37 on the opposite side of the conductive portion 40 is axially positioned in proximity to the stopper 26 so as to be partially faced therewith.
The extended portion 29 is arranged on the outer surface of the holder 20 or the outer surface perpendicular or substantially perpendicular to the planar surface of the chassis 13 and including the escape opening 25 of the container room 23. The extended portion protrudes from between the chassis 13 and the escape opening 25, and extends along the planar surface of the chassis 13. This results in a long creepage distance from the inside of the container room 23 to the front surface of the chassis 13. Thereby, a leak, from the discharge tube 15 held in the container room 23 to the chassis 13 outside the holder 20, can be prevented.
Referring to
The circuit board 17 preferably has a vertically-elongated rectangular shape as a whole, and is preferably formed using a phenolic paper-base copper-clad laminated board (known as a phenolic paper). A plurality of fitting holes 17H having a vertically-elongated rectangular shape are formed through the circuit board 17 so as to extend from the front side to the back side (See
While the circuit board 17 is kept parallel or substantially parallel to the chassis 13, the power board 16 is moved toward the chassis 13 from the back side and is fixed thereto. At the time of fixation, the wall portions 22 of the relay connectors 14 and the board connecting portions 33 arranged along the wall portions 22 penetrate the circuit board 17 through the fitting holes 17H and are inserted into the engaging recesses 27 of the on-board connectors 18. Thereby, the on-board connectors 18 are fitted onto the relay connectors 14, and the output terminals are conductively connected to the relay terminals 31.
In the above lighting device 10, the liquid crystal display device D including the lighting device 10, and the television receiver TV having the liquid crystal display device D, the discharge tubes 15 included in the lighting device 10 have ferrules 36, which include elastic members 38 capable of elastic and radial deformation so as to change their inner diameter depending on the outer diameter of the glass tube 34. According to the construction, if the outer diameter of the glass tube 34 is changed due to a design change for varying the brightness of discharge tubes 15 according to the type of the liquid crystal display device D, the same ferrules 36 as those having been used before the design change can be used as common ferrules. In the case of the glass tube 34 having a tube diameter of about 3 mm, for example, according to the present preferred embodiment, the elastic members 38 (38A, 38B) can undergo elastic deformation as shown in
The elastic members 38 (38A, 38B) are arranged and adapted to undergo elastic deformation while having contact with the outer surface (or outer circumferential surface) of a glass tube 34 in the course of insertion of the glass tube 34 into (the body 37 of) the ferrule 36. According to this construction, the glass tube 34 can be smoothly inserted into the ferrule 36. Further, the elastic members 38 (38A, 38B) are arranged at even intervals along the circumferential direction of the ferrule 36, so that the inner diameter of the ferrule 36 can vary evenly along the radial direction. Consequently, the ferrule 36 can be fitted on the glass tube 34 in a balanced manner, while being prevented from uneven radial variation.
The elastic members 38 include first elastic members 38A and second elastic members 38B, which are arranged at the respective axial ends of (the body 37 of) the ferrule 36. According to the construction, the radial variation according to the outer diameter of the glass tube 34 is possible at the respective ends of (the body 37 of) the ferrule 36, and thereby the inner diameter of (the body 37 of) the ferrule 36 can be provided uniformly along the axial direction. Consequently, the ferrule 36 (or the body 37 thereof) can be fitted on the glass tube 34 in a balanced manner.
Particularly, the first elastic members 38A provided at the side of the glass tube 34 inlet and the second elastic members 38B provided at the side of the conductive portion 40 are alternately arranged in a staggered configuration when the ferrule 36 is viewed along the axial direction. Thereby, the glass tube 34 fitted thereto can be stably held therein. That is, the contact points between the ferrule 36 and the glass tube 34 are arranged so that those provided on one end portion are displaced along the circumferential direction from those provided on the other end portion, which enables stable fitting.
The elastic members 38 include curved portions 39, which are bent to bulge radially inwardly from the inner surface of the ferrule 36. The elastic members further include inclined surfaces 80 extending from the apexes of the curved portions 39 to the end portion of the ferrule 36. The glass tube 34 can be guided into the ferrule 36 along the inclined surfaces 80. The elastic members 38 thus constructed can combine a function for enabling variation of the inner diameter of the ferrule 36 and a function for guiding the glass tube 34. Consequently, the insertion of the glass tube 34 into the ferrule 36 is facilitated, and the variation of the inner diameter of the ferrule 36 can be adequately achieved due to elastic deformation of the elastic members 38 during the insertion.
Described above are preferred embodiments of the present invention. However, the present invention is not limited to the preferred embodiments explained in the above description made with reference to the drawings. The following embodiments may be included in the technical scope of the present invention, for example.
The leaf-spring elastic members 38 are preferably described above as optimal inner-diameter-changing elastic members. However, the inner-diameter-changing elastic members are not limited to this construction, but rather may be formed of bulging rubber members arranged to protrude from the inner surface of the body 37 of the ferrule 36.
The first elastic members 38A and the second elastic members 38B, which are arranged at the respective ends of (the body 37 of) the ferrule 36, are shown as inner-diameter-changing elastic members, for illustrative purposes. However, the elastic members may be provided solely at one end portion (i.e., preferably, the end portion on the inlet side).
The three pairs of elastic members 38 preferably arranged in the circumferential direction are shown for illustrative purposes. However, one elastic member or any number of elastic members may be provided. Further, the elastic members 38 are not limited to being defined by cantilevered portions extending anteriorly or posteriorly, but rather may be formed of two-point supported portions which are supported on the body at their anterior and posterior ends.
The first elastic members 38A and the second elastic members 38B of the elastic members 38 are alternately arranged in a staggered configuration when the ferrule 36 is viewed along the axial direction. Particularly, the first elastic members 38A and the second elastic members 38B may be arranged at intervals of about 60°, for example, as shown in
According to the construction in which the first elastic members 38A are thus arranged at intervals of X° (e.g., about 120° in one preferred embodiment) along the circumferential direction while the second elastic members 38B are arranged to be shifted by a distance of about X/2 (e.g., about 60° in one preferred embodiment) from the respective first elastic members 38A when the ferrule 36 is viewed along the axial direction, the ferrule 36 can be fitted on the glass tube 34 in a more balanced manner.
A metallic material other than stainless steel may be used for ferrules 36. Alternatively, a nonmetallic material, such as a conductive resin or a conductive rubber, may be used instead. The outer leads 35 projecting from a glass tube 34 are not limited to being arranged concentrically with the glass tube 34, but rather may be arranged radially eccentrically with respect to the axis of the glass tube 34. Further, the outer leads 35 linearly projecting from a glass tube 34 are not limited to being arranged parallel or substantially parallel to the axis of the glass tube 34, but rather may be arranged at an angle with the axis of the glass tube 34. Moreover, the outer leads may be arranged crookedly.
The discharge tubes 15 are not limited to cold cathode fluorescent tubes. Hot cathode fluorescent tubes, xenon tubes or the like may be used instead. The portion of the conductive portion 40 to be connected to the outer lead 35 is not limited to having a cylindrical shape capable of circumferentially surrounding the outer lead 35. It may be provided as a substantially U-shaped or V-shaped portion so that the valley portion of the U or V shape can have contact with the outer lead. Alternatively, the conductive portion 40 may be provided to have a plate-shaped distal end portion that can have contact with the outer periphery of the outer lead 35. In this case, a valley may be formed on the plate-shaped distal end portion of the conductive portion 40, so that the outer lead 35 can engage with the valley.
The liquid crystal panel 11 of the liquid crystal display device D is not limited to having TFTs as switching elements, but rather may include, as switching elements, elements other than TFTs such as MIM (Metal Insulator Metal) elements. The display device is not limited to a liquid crystal display device D. Various display devices requiring a lighting device on the back side of a display panel can be included.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-212327 | Aug 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/055423 | 3/24/2008 | WO | 00 | 2/8/2010 |
