Patent Application
20080036396
These and other objects, advantageous effects and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings which illustrate specific embodiments of the invention. In the drawings:
The following describes a preferred embodiment in which the present invention is applied to a compact self-ballasted fluorescent lamp-a type of low-pressure mercury vapor discharge lamp with the aid of diagrams.
A compact self-ballasted fluorescent lamp 1 includes, as shown in
Regarding the arc tube 3 to be further described later, an electrode is fixed to each of both end portions of a glass tube 13 wound in a double spiral, and a discharge space is formed inside the glass tube 13 when the end portions are closed by fixing the electrode thereto.
The retainer 5 has a cylindrical shape with one end closed, being made up of a peripheral wall 15 and an end wall 17 that blocks of f one end of the peripheral wall 15. On the end wall 17, receiving holes are formed for allowing end portions 3a and 3b of the arc tube 3 to be inserted therethrough to the inside of the retainer 5.
The retainment of the arc tube 3 is realized by inserting the end portions 3a and 3b of the arc tube 3 to the inside of the retainer 5 through the receiving holes, and then firmly fixing the end portions 3a and 3b of the arc tube 3 in such a state to the inner surface of the retainer 5 by an adhesive agent (for example, silicone) 19.
The electronic ballast 7 is of a series-inverter type composed of multiple electrical components, such as a capacitor and a choke coil, and a substrate 21 for mounting these electrical components is attached to the retainer 5 at the open end thereof.
The substrate 21 is attached to the retainer 5 by such a means that multiple locking arms 15a extending in the direction parallel to the central axis of the retainer 5 from the edge of the opening of the peripheral wall 15 engage with the periphery of the substrate 21. Note that multiple—for example, two—locking arms 15 are provided at even intervals in the circumferential direction of the peripheral wall 15.
The case 9 has a shape of a cone, for example, and includes a large diameter cylinder portion 9a, a small diameter cylinder portion 9b which has a smaller diameter than the large diameter cylinder portion 9a, and a funnel-shaped cylinder portion 9c connecting the large and small diameter cylinder portions 9a and 9b. On the small diameter cylinder portion 9b of the case 9, a screw base 23, such as E17, is attached.
The case 9 and the retainer 5 are attached to each other by such a means that engaging projection portions 15b formed on the outer surface of the peripheral wall 15 of the retainer 5 engage with locking depressions 9d formed on the inner peripheral surface of the case 9. Regarding the engaging projection portions 15b and locking depressions 9d, multiple pieces—for example, four—of each are provided on the case 9 or the retainer 5 at even intervals in the circumferential direction. It is sufficient if they are provided on either one of the case 9 and the retainer 5.
Note that the “case” of the present invention corresponds to the retainer 5 and the case 9 of the present embodiment, and may be a single-piece construction of the retainer and the case, or may be formed with separate pieces of the retainer 5 and the case 9.
The globe 11 here is, for example, of an A type. The globe 11 is firmly fixed to the case 9 and the retainer 5 by such a means that an end portion 11a positioned on the opening side of the globe 11 is inserted into the gap between the above-mentioned case 9 and retainer 5, and then an adhesive agent 25, such as silicone, is filled in the gap.
At a bottom 11b (lowermost part in
Note that on the internal surface of the globe 11, a calcium carbonate-based diffuser film is applied.
The arc tube 3 includes an arc tube main body 31 formed by the wound glass tube 13 and electrodes 33 fixed to the end portions 3a and 3b of the arc tube main body 31. In this description, the electrode 33 is described to be fixed to each of the end portions 3a and 3b of the arc tube main body 31; however, this represents the same configuration as that in which the electrode 33 is fixed to each end portion of the glass tube 13 of the arc tube main body 31.
Although
The arc tube main body 31 has a double spiral structure in which the glass tube 13 doubly spiral in a direction B around a pivotal axis A. Note that the number of winding turns around the pivotal axis A is decided based on the lamp specification (rated lamp wattage and the like). Parts of the glass tube 13 close to the end portions 3a and 3b of the arc tube main body 31 are wound in a manner to have a larger gap therebetween with immediately adjacent parts of the glass tube 13 in the direction of the pivotal axis A.
On the inner surface of the arc tube main body 31 (glass tube 13), a phosphor layer 35 is formed. The phosphor layer 35 includes one or more kinds of phosphors, such as rare earth phosphors. In the arc tube main body 31, mercury functioning as a light-emitting material, a rare gas functioning as a buffer gas and the like are enclosed.
The electrode 33 includes the filament coil 41 and the paired lead wires 43 and 45 supporting the filament coil 41 therebetween in a manner that the filament coil 41 hangs across the lead wires 43 and 45 at their tips on one side (i.e. the lead wires 43 and 45 retain the filament coil 41 so as to bridge them), as shown in
The bead glass 47 above is provided, on the paired lead wires 43 and 45, on the opposite side from the filament coil 41 in relation to a region of the lead wires to which pinch-sealing is applied. That is, the paired lead wires 43 and 45 are pinch-sealed at the end portion 3a/3b of the arc tube main body 31 with the filament coil 41 disposed therein, as described later. Then, the bead glass 47 is provided on the lead wired 43 and 45 in a manner to straddle them on the opposite side from the filament coil 41 in relation to the region for the pinch-sealing application (corresponding to the “region of the lead wires for application of the pinch-sealing” of the present invention).
The filament coil 41 is formed by multiple-coiling, for example, a tungsten wire (a coil state) (the part wound in a coil configuration is referred to as a “coil portion” and indicated by a reference letter “41a”). With the filament coil 41, the number of winding turns of the last coiling stage is substantially one. Note that the filament coil 41 is filled with an electron emissive material.
Each of the tips of the paired lead wires 43 and 45 extending from the bead glass 47 toward the filament coil 41 is folded back in a manner to hold therebetween the end portion of the filament coil 41, as shown in
As shown in
In the discharge space portion 43a/45a of the lead wire 43/45, one or more bends—here, a single bend 43d/45d—are formed so that the lead wire 43/45 follows the shape of the end portion 3a of the arc tube main body 31. Note that, when the lead wires 43 and 45 are yet to be inserted into the arc tube main body 31, the discharge space portions 43a and 45a of the above lead wires 43 and 45 are yet portions of the lead wires 43 and 45 planned to be disposed inside the glass tube 13.
The reason that the bend 43d/45d is provided in the discharge space portion 43a/45a is to prevent the filament coil 41 from coming in contact with the inner surface of the arc tube main body 31 when the filament coil 41 is inserted into the end portion 3a of the arc tube main body 31.
Also, in the external portion 43c/45c of the lead wire 43/45 of the electrode 33 fixed to the end portion 3a of the arc tube main body 31 together with a thin tube 51, one or more bends-here, two bends 43e/45e and 43f/45f—are formed in a manner that the bead glass 47 is disposed outside the thin tube 51 so as not to interfere with the thin tube 51, as shown in
The electrode 33 is fixed to the arc tube main body 31 by such a means that the end portion 3a of the arc tube main body 31 is pinch-sealed at a part of the paired lead wires 43 and 45, between the bead glass 47 and the filament coil 41.
The discharge space 49 is formed inside the arc tube main body 31 when the end portion 3a of the arc tube main body 31 is sealed (precisely speaking, when the thin tube 51, to be described hereinafter, is sealed).
At the end portion 3a of the arc tube main body 31, the thin tube 51 is sealed together with the electrode 33. The thin tube 51 is used to form a vacuum inside the arc tube main body 31 and feed in mercury, a buffer gas and the like therefrom to the inside of the arc tube main body 31 after the electrode 33 is fixed. After gas is exhausted from the arc tube main body 31 and then mercury and a buffer gas are fed in, the thin tube 51 is sealed using, for example, a tip-off method. <Method of Manufacturing Arc Tube>The following describes the method of manufacturing the arc tube 3, especially the fixing process for the arc tube main body 31. Here, the mount (the “electrode mount” of the present invention) also refers to an electrode assembly yet to be fixed to the arc tube main body, and includes the filament coil 41, the paired lead wires 43 and 45, and the bead glass 47 (retainer).
First, the above-mentioned arc tube main body 31 formed in a double spiral structure, an electrode mount 61, and a thin tube 63 are prepared as shown in
Although having basically the same structure as a publicly known bead-glass type electrode, the mount 61 differs from it in that the bead glass 47 is attached, on the lead wires 43 and 45, at a position farther away from the filament coil 41 as compared to the conventional one.
The fixing process for the arc tube main body 31 here is described with reference to the mount 61 fixed to the one end portion 13a of the arc tube main body 31 together with the thin tube 63; however, fixing of the mount at the other end portion 13b of the arc tube main body 31 is also performed in a similar fashion.
Next, the arc tube main body 31 is retained rotatably around the pivotal axis. Then, the mount 61 is retained in such a manner that, when the arc tube main body 31 rotates, the filament coil 41 goes into the arc tube main body 31 (glass tube 13) from the end thereof.
At this point, the paired lead wires 43 and 45, which support the filament coil 41 therebetween in a manner that it hangs across the lead wires 43 and 45, are retained by the bead glass 47 positioned a predetermined distance away from the filament coil 41. Therefore, it is possible to prevent the filament coil 41 from wobbling, or from breaking off as a result of an increase in the gap between the tips of the paired lead wires 43 and 45. This realizes efficient handling of the mount 61 when it is inserted into the arc tube main body 31.
Subseqently, the arc tube main body 31 is rotated in a direction that the arc tube main body 31 comes closer to the mount 61, as shown in
At this point, the bead glass 47 of the mount 61 is located outside the arc tube main body 31, and therefore the distance between the filament coil 41 and the end face of the arc tube main body 31 can be set short. Accordingly, even when the fixing process of the mount 61 is performed at the end portion 3a of the double-spiral arc tube main body 31 having a small curvature radius, it is possible to prevent the filament coil 41 from coming in contact with the inner surface of the arc tube main body 31.
Furthermore, as compared to the case of using a conventional mount in which the bead glass (47) is disposed inside the arc tube main body (31), the insertion length of the mount 61 into the arc tube main body 31 can be set shorter, and accordingly the insertion of the filament coil 41 into the arc tube main body 31 is readily realized.
Note that, if the filament coil 41 comes in contact with, for example, the inner surface of the arc tube main body 31, the temperature of the electrode 33 (filament coil 41) is lowered during the period when the lamp is lit, whereby shortening the operating life and the like.
Next, the end portion 3a of the arc tube main body 31 is heated by, for example, a gas burner and then crushed using a pinch block. Herewith, the sealed-in portion 43b/45b of the lead wire 43/45 of the mount 61 and the thin tube 63 are welded to the end portion 3a of the arc tube main body 31.
Note that the fixing process of the mount (61) at the other end portion 3b of the arc tube main body 31 can be realized in the same manner as for the above mount 61. After mercury, a rare gas and the like are filled in the arc tube main body 31 through the thin tube 63, the end portion of the thin tube 63 is tipped off and sealed, thereby the arc tube 3 is completed.
Thus, the mount 61 of the present invention allows for a short insertion distance of the filament coil 41 into the arc tube main body 31. This means that the insertion length of the lead wires 43 and 45 into the arc tube main body 31 can be made short. As a result, the overall length of the glass tube 13 can be made short, enabling the arc tube 3 to be compact in size.
<Method of Manufacturing Lamp>
The lamp 1 is manufactured with the following processes: an arc tube attachment process of attaching the arc tube 3 manufactured in the above-mentioned method to the retainer 5; an ballast fitting process of fitting the substrate 21, on which electrical components making up the electronic ballast 7 are mounted, to the retainer 5; a case attachment process of attaching the case 9 to the retainer 5, to which the electronic ballast 7 has been fitted, so as to provide an outside covering; and a globe fitting process of fitting the globe 11 to the case 9 and the retainer 5.
With the arc tube 3 having the above structure, the paired lead wires 43 and 45 extending outwardly from the end portions 3a and 3b of the arc tube 3 are retained by the bead glass 47. As a result, the lead wires 43 and 45 are less likely to get tangled with each other when the arc tube 3 is attached to the retainer 5, thus facilitating the attachment of the arc tube 3 to the retainer 5.
Especially with the recent lamp 1, the overall size of the lamp has been reduced, resulting in that the electrical components making up the electronic ballast 7 housed in the case 9 are closely spaced from one another. As a result, a short circuit is more likely to occur due to the lead wires 43 and 45 extending from the end portions 3a and 3b of the arc tube 3 coming in contact with each other, or with another electrical component, which consequently leads to a reduction in quality of the lamp. However, the paired lead wires 43 and 45 are retained, by the bead glass 47, in a manner that they have a predetermined space therebetween (i.e. being parallel to each other), whereby preventing the lead wires 43 and 45 from coming in contact with each other. As a result, the quality and reliability of the lamp can be improved.
<Practical Example>
The following explains a practical example of the arc tube of the above embodiment.
(1) Electrode Mount
First, the mount 61 is explained. A tungsten wire with a wire diameter of 0.036 mm is used for the filament coil 41, and iron-nickel-chrome alloy with a wire diameter of 0.35 mm is used for the paired lead wires 43 and 45.
The coil portion 41a (see
The bead glass 47 has a shape of an oval sphere, as shown in
The gap between the paired lead wires 43 and 45 is 3.5 mm at a point where the filament coil 41 is disposed and 3.0 mm at a point where the bead glass 47 is disposed.
In addition, to facilitate the insertion into the double-spiral arc tube main body 31, the bend 43d/45d is provided within the part of the lead wire 43/45, located inside the arc tube main body 31 (i.e. the discharge space portion 43a/45a of the lead wire 43/45), in accordance with the curvature (shape) of the spiral arc tube main body 31.
The bends 43d and 45d are provided approximately 4.7 mm away from the central axis of the filament coil 41 toward the bead glass 47. At the bend 43d/45d, the lead wire 43/45 is bent twice in different directions (two different bending directions of the lead wire 43/45, shown in
One bending direction makes an angle of 29°, as indicated by “A1” of
Within each of the lead wires 43 and 45, the sealed-in portion 43b/45b sealed at the end portion 3a of the arc tube main body 31 together with the thin tube 51 and the external portion 43c/45c disposed outside of the arc tube main body 31 have two bends 43e/45e and 43f/45f so that the bead glass 47 and the thin tube 51 do not interfere each other.
The bends 43e and 45e are positioned 14 mm away from the filament coil 41 (“L2” of
(2) Arc Tube Main Body
The glass tube 13 of the arc tube main body 31 is made of a lead-free glass material. As shown in
For the phosphor layer 35 formed on the inner surface of the glass tube 13 of the arc tube main body 31, three kinds of rare-earth phosphors of, for example, red (Y2O3:Eu), green (LaPO4:Ce,Tb) and blue (BaMg2Al16O27:Eu,Mn) are used.
1 mg mercury is enclosed in the arc tube main body 31, and rare gases used are mixed gas of argon and krypton sealed at 550 Pa.
In the arc tube 3 completed with the mount 61 being fixed to the end portion 3a/3b of the arc tube main body 31, the part of each lead wire 43/45 disposed in the discharge space 49 has a length of 5 mm, and the bead glass 47 is disposed approximately 10 mm away from the end portion 3a/3b of the arc tube main body 31.
Note that, in the conventional arc tube having bead glass therein, the part of each lead wire disposed in the discharge space is 10 mm in length. Therefore, according to the present invention, the glass tube of the arc tube can be reduced by 5 mm for each electrode (in total, 10 mm), as compare to the conventional arc tube.
The distance between the central axes of two filament coils in the discharge space—i.e. a so-called electrode distance is 400 mm.
It has been determined that a lamp with the above-mentioned arc tube achieves, with an input power of 12 W, an initial luminous flux of 810 lm, which is the same as that of a common 60 W incandescent lamp.
As to the lamp 1 in which the electrode 33 has a typical structure according to the present embodiment, the overall length of the part of each lead wire 43/45 of the electrode 33 airtightly sealed in the arc tube 3 (i.e. discharge space portion 43a/45a) is approximately 5 mm. This enables an approximately 506 reduction from the conventional electrode, about 10 mm.
Accordingly, the arc tube 3 can be made compact in size with 33 mm in outer circumference, as compared to the conventional arc tube, 36 mm. In addition, since the inner diameter D1 of the glass tube 13 can be made comparatively small—for example, 7 mm or less, the present invention is applicable to a small-size double spiral arc tube 3.
Furthermore, at the end of the operating life of the lamp, the operation of the lamp 1 can be stopped by that heat released from the filament coil 41 is transmitted, via the lead wires 43 and 45, to a sealing portion by which the electrode 33 is fixed or a part of the glass tube 13 adjacent to the sealing portion. Then, the sealing portion or the adjacent part is melted by the heat, thereby allowing external air to flow into the arc tube 3.
<Modifications>
The present invention has been described based on the above preferred embodiment; however, it is a matter of course that the present invention is not limited to the specific examples described in the above embodiment. The following modifications are also within the scope of the present invention.
1. Lamp and Arc Tube
The electrode, or mount, according to the present invention is also applicable to compact fluorescent lamps that have recently been widely in use as an energy saving light source together with compact self-ballasted fluorescent lamps. Note that compact fluorescent lamps include an arc tube, a case retaining the arc tube (corresponding to the retainer and the case of the embodiment, which may be a single-piece construction of the retainer and the case, or may be formed from separate pieces), a single base (e.g. G10 type) attached to the case and supplying power to the arc tube.
Furthermore, the electrode, or mount, of the present invention is basically applicable to various common lighting fluorescent lamps—for example, straight tube fluorescent lamps and circule tube fluorescent lamps, and small-size fluorescent lamps for liquid crystal back-lighting devices.
That is to say, the present invention is applicable to low-pressure mercury vapor discharge lamps including the above-mentioned various types of lamps.
The above preferred embodiment and modifications show the examples in which the present invention is applied to a spiral arc tube main body. However, it can be also applied to such an arc tube that the end portions of the glass tube, to which the electrode mount is fixed, are curved and therefore the insertion of the filament coil into the arc tube main body is difficult.
It is a matter of course that the mount of the present invention can be applied to a straight arc tube whose glass tube has uncurved end portions.
2. Bead Glass (Retainer)
In the preferred embodiment above, the bead glass (47) disposed outside the arc tube main body 31 is left after the assembly of the lamp. However, the bead glass can be removed at any time after the fixing process—i.e. after the arc tube is fitted to the retainer, or after the lead wires of the arc tube and the substrate are electrically connected to each other, let alone immediately after the fixing process.
Note that the electrode, from which the bead glass has been removed after the fixing process, is composed of the filament coil and the paired lead wires.
To remove the bead glass, the bead glass may be melted by heat application, split up, or crushed. In such a case, the part of the lead wires to which the bead glass was attached has a different color as compared to the rest of the lead wires.
In the preferred embodiment, the bead glass has a shape of an oval sphere; however, it may have a different shape, such as a sphere, a multi-sided prism, or a multi-sided pyramid.
3. Retainer
In the preferred embodiment above, the bead glass made of a glass material is used as the retainer; however, a different material can be used instead.
For example, a ceramic material and a resin material can be used instead. In view of the current supply to the filament coil via the lead wires, however, the material of the retainer is preferably an insulating material. Note however that the retainer may be made of a conductive material if insulation is provided by, for example, forming an insulating film on the lead wires. Also, in view of the temperature of the filament coil during the lighting, the retainer is desirably made of a high heat-resistant material.
Although the present invention has been fully described by way of examples with reference to the accompanying drawings, it is to be noted that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be constructed as being included therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-219971 | Aug 2006 | JP | national |
| 2007-178491 | Jul 2007 | JP | national |
