Patent Application
20070278959
In the accompanying drawings:
Hereunder, preferred embodiments according to the present invention will be described with reference to the accompanying drawings. Further, it is to be noted that the same reference numerals are assigned to the same or corresponding portions shown in the plurality of accompanying drawings, and also noted that terms “upper”, “lower”, “right”, “left” and the like terms are used herein with reference to the illustrated embodiments.
As shown in
The base 2 is an Edison type model E26, or the like, and includes a cylindrical shell 2a having a thread formed thereon, and an eyelet 2c provided on the bottom thereof adjacent to one end of the shell 2a through an electrically insulating portion 2b. The other end of the shell 2a covers one end portion of the cover 3, and the shell 2a is fixed to the cover 3 by means of an adhesive agent or caulking.
The cover 3 includes a cover body 3a, which is, for example, formed of a heat-resistant synthetic resin such as polybutylene-terephthalate (PBT), in which an inverted frustum shaped portion that gradually reduces its diameter in the downward direction in
The cylindrical lower open end of the holder 5 is engaged with the protruded step portion 3c of the cover body 3a, which is located inside the connection between the frustum shaped portion and cylindrical portion of the cover body 3a inside the open fitting end 3b.
That is, the holder 5 is formed of a heat-resistant synthetic resin such as PBT and formed into a cylindrical shape having a closed end at one side forming a disc-shaped base portion 5a. A cylindrical portion 5b is integrally formed so as to extend from the peripheral end of the base portion 5a toward the lower end of the holder 5 (i.e., lower end in
The holder 5 includes support recesses and a cylindrically projecting portion 5c, which are formed on the base portion 5a. A pair of end portions 4a sealing electrodes (electrode sealing end portions) 4a, 4b of the arc tube 4 are mounted and supported by the support recesses. The cylindrically projecting portion 5c projects into a gap formed between these electrode sealing end portions 4a, 4b to restrict their radial displacement. The base portion 5a has through holes 5d, 5e both formed on the outer side of the cylindrically projecting portion 5c. The through holes 5d, 5e are formed so as to pass narrow tubes 4c extending outward from the pair of the electrode sealing end portions 4a, 4b of the arc tube 4, and outer wires 4d shown in
The globe 6 is formed of a transparent or light diffusion material such as glass or synthetic resin. The globe 6 is formed so as to provide a smooth curved shape that is approximate to the shape of a glass bulb of a general light bulb such as an incandescent light bulb. That is, the globe 6 has a spherical portion 6a, which is substantially spherical, and a substantially cylindrical small-diameter portion 6b, having a diameter gradually reduced to be smaller than the diameter of the spherical portion 6a. The spherical portion 6a is continuously and integrally formed at the lower end thereof as shown in
The globe 6 is formed so as to have a thickness of, for example, 1.5 mm, and have the maximum-diameter portion 6c of an outer diameter of 55 to 66 mm which is 2.0 to 2.5 times the outer diameter φ 3 (26 mm) of the base 2, the maximum-diameter portion 6c being accorded with the maximum diameter 4k of the arc tube 4. Furthermore, the outer diameter of the small-diameter portion 6b of the globe 6 is formed to be 26 to 39 mm, which is 1.0 to 1.5 times the outer diameter φ 3 of the base 2. Further, the base 2 having the outer diameter of 17 mm may be also utilized.
In addition, the compact fluorescent lamp 1is formed, as shown in
The globe 6 is longitudinally divided into a left half portion 6X1 and a right half portion 6X2 in
That is, if the globe 6 is, for example, not divided and formed integrally, the arc tube 4 cannot be inserted into the globe 6 through the open end portion 6d because the maximum outer diameter portion 4k of the arc tube 4 has an outer diameter larger than the open end portion 6d of the globe 6.
However, since the globe 6 is divided into the left half portion 6X1 and the right half portion 6X2 with respect to the central axis O, after the arc tube 4 is mounted at the position on the holder 5, the arc tube 4 is covered with the left half portion 6X1 and right half portion 6X2 of the globe 6 from its side, and the left half portion 6X1 and right half portion 6X2 are connected, thus making it possible to attach them to the cover 3.
Thereafter, the globe 6 is covered with a pouch-like heat-shrinkable film having a desired shape, not shown. By heat-shrinking the heat-shrinkable film, the left half portion 6X1 and right half portion 6X2 of the globe 6 may be integrated together.
It is to be noted that the globe 6 may be divided in a transverse direction (horizontal direction). In this case, as shown by a broken line in
The arc tube 4 includes a spiral portion 4e formed at its upper and intermediate portions in
The spiral portion 4e is formed by folding a glass bulb 4g of straight cylindrical tube shape having an outer diameter of, for example, 8.5 mm substantially in half, winding the same around a die, not shown, at the middle position thereof, i.e., a turn-back portion 4h, made as the top end, and then molding the same into a double helix shape.
The glass bulb 4g has a fluorescent material film, made of a rare earth, metal oxide or the like, formed on its inner surface. The fluorescent material film is formed substantially over the overall length of the glass bulb 4g. The glass bulb 4g has the electrode sealing end portions 4a, 4b formed at the ends thereof in the axial direction, respectively, so as to seal a pair of electrodes 4i, 4j.
That is, as shown in
The pair of electrodes 4i, 4j are formed of, for example, a coil electrode made of tungsten and are, for example, sealed within the ends of the glass bulb 4g and temporarily connected by using bead glass.
A discharge medium, such as argon gas and krypton gas, is encapsulated inside of the glass bulb 4g. The narrow tubes 4c are formed on the outer surfaces of the pair of electrode sealing end portions 4a, 4b so as to communicate with the inside thereof. Mercury or amalgam is accommodated in the narrow tubes 4c.
The spiral portion 4e is accommodated in the spherical portion 6a of the globe 6 adjacent to the open end portion 6d including the maximum-diameter portion 6c. The spiral portion 4e gradually increases its helix diameter from the turn-back portion 4h of the top end toward the maximum-diameter portion 6c in correspondence with the inner surface shape of the spherical portion 6a of the globe 6, having a maximum helix diameter at the maximum-diameter portion 6c of the globe 6, and then gradually reduces its helix diameter in correspondence with the reduction in diameter of the lower half portion of the spherical portion 6a of the globe 6. The spiral portion 4e is continuously and integrally formed with the upper end portions (in
As shown in
Further, the straight portions 4f may be formed into a spiral shape by slightly curving the glass bulb 4g so as to coincide with the turning direction of the spiral portion 4e. However, in this case, the die for forming the spiral portion 4e is withdrawn, the bending working may be done manually or turned by using an easy die, so that the helical pitch becomes less dense than the spiral portion 4e, and as a whole, it is formed as a sparse pitch portion.
Incidentally, the lighting control circuit unit 7 has a longitudinal substrate 7a, on which a lighting circuit pattern is formed, and which is fixedly fitted into a pair of longitudinal grooves formed in the inner surface of the base 2. That is, the base 2 has a pair of longitudinal grooves formed in its inner surface to extend in the axial direction of the base 2 so as to face each other along the diameter. Both widthwise edges of the longitudinal substrate 7a are fixedly fitted into the longitudinal grooves.
The longitudinal substrate 7a is formed so as to be a single-sided substrate or a double-sided substrate. A plurality of electrical components 7b, which are lighting circuit components including lead components such as electrolytic capacitors and chip components such as transistors are mounted on the mounting surface of the longitudinal substrate 7a.
One example of the specific configuration of the above configured compact fluorescent lamp 1 is as follows. That is, the maximum outer diameter of the arc tube 4 (helix outer diameter) φ2 is 54 mm, the height h1 of the arc tube 4 is 64÷1 mm, and the height h2 from the horizontal central axis of the maximum-diameter portion 4k of the arc tube 4 to the outer surface of the pair of electrode sealed end portions 4a, 4b is about 40 mm. The discharge path length between the pair of electrodes 4i, 4j is 360 to 610 mm, which varies depending on the bulb diameter of the glass bulb 4g. For example, when the diameter of the glass bulb 4g (bulb diameter) is 8 mm, the discharge path length is 476 mm. When the bulb diameter is 9 mm, the discharge path length is 374 mm. In addition, the outer diameter φ3 of the base 2 is 26 mm, and the maximum width w1 between the straight portions 4f, 4f of the arc tube 4 is approximately 1.17 times larger than the maximum outer diameter φ2 (30.5 mm) of the arc tube.
Thus, according to the compact fluorescent lamp 1 of this embodiment, the appearance approximate to the general light bulb may be obtained.
Furthermore, the spiral portion 4e of the arc tube 4 is accommodated in the spherical portion 6a having a relatively large internal volume, including the maximum-diameter portion 6c of the globe 6, so that the bulb diameter and the helix diameter both may be increased. For this reason, it is possible to increase light flux in the spiral portion 4e and also to improve luminous efficacy.
In addition, the straight portions 4f, which are the short discharge path portions of the arc tube 4 accommodated in the space adjacent to the narrow small-diameter portion 6b of the globe 6, each have a discharge path length shorter than the spiral portion 4e, so that the discharge path length required for the arc tube 4 is mostly assigned to the spiral portion 4e, thus being possible to make the bulb diameter have the same thick diameter as the spiral portion 4e. For this reason, it is possible to make the bulb diameter thick substantially over the overall length of the arc tube 4, including the straight portions 4f and spiral portion 4e of the arc tube 4.
Accordingly, the surface area per unit length of a fluorescent material film formed on the inner surface of the glass bulb 4g or the cross-sectional area of the bulb may be adjusted to an optimum value, making it possible to improve luminous efficacy.
Furthermore, since both the bulb diameter and the helix diameter are increased, it is possible to easily form the glass bulb 4g into a spiral shape through a molding process with a die and, in addition, it is possible to reduce an occurrence of cracking or distortion when the spiral portion is molded. As a result, both the mass productivity and yield percentage of the glass bulb 4g having the spiral portion 4e could be improved.
Moreover, since the bulb has a large diameter, the starting voltage and lamp voltage of the arc tube 4 may be decreased. For this reason, the output voltage of the lighting device 7 need not be increased, and the withstand voltage of components used may be lowered. Thus, it is possible to reduce manufacturing costs and, in addition, to prevent or suppress an increase in size of the lighting control circuit unit 7.
Still furthermore, the spiral portion 4e of the arc tube 4 includes the glass bulb 4g that is formed into a spiral shape, and accordingly, the light emitted inside the spiral portion 4e is likely to be blocked by the inner surface of the spiral glass bulb 4g itself. Thus, the light flux to be radiated outside of the spiral portion 4e can be reduced. However, the straight portions 4f extend in substantially parallel with the axial direction thereof in the inside of the small-diameter portion 6b of the globe 6, and accordingly, many gaps are formed and there is a little portion being blocked by the arc tube 4. Thus, the light emitted inside the spiral portion 4e and inside the straight portions 4f can increase the light flux to be radiated outside from the side adjacent to the small-diameter portion (lower side in
It is further to be noted that, according to the present invention, the straight portions 4f may be formed as the sparse pitch portion having a less dense spiral shape than the helical pitch of the spiral portion 4e.
That is, the sparse pitch portion may be formed so that the lower portion in
For this reason, the sparse pitch portion is formed as a short discharge path portion having a discharge path length shorter than that of the spiral portion 4e by a desired length, and the spiral portion 4e is formed as a dense pitch portion having a helical pitch denser than the sparse pitch portion, while it is formed as a long discharge path portion having a long discharge path length.
Therefore, the sparse pitch portion has lower light flux and lower luminous efficacy. However, it has a sparse helical pitch, thus being possible to allow light emitted inside the spiral inner surface of the sparse pitch portion to increase the light flux to be radiated outside through a gap of the helical pitch.
That is, the arc tube 4 is formed in a manner such that the glass bulb 4g in straight circular tube shape bend into equal two portions is entirely heated and softened, which is then wound up around a die, not shown, to thereby form a double spiral-shaped spiral portion 4e.
At this time, the spiral portion 4e is formed with a vertically pair of straight tube shaped portions 4f1, 4f2 extending linearly outward in a centrifugal direction from lateral end portions Oa1, Oa2 in the diameter direction of the maximum-diameter portion 4K in
Next, the straight end portions 4f1, 4f2 are bent, approximately in spiral form, around the central axis O by a spiral diameter smaller than the maximum diameter portion 6c without using any die or by using a small second die, and then directed downward on the side of the base 2 in
Accordingly, as shown in
Therefore, these paired straight portions 4f, 4f are formed not directly straightly from both the end portions Oa1, Oa2 in the diameter direction of the maximum-diameter portion 4e, and directly formed through the spiral bent portion “a” and the reduced diameter bent portion “b” in a range of the half peripheral portion of the spiral shape (about 180 degrees), so that in comparison with the directly straightly formed case, the generation of glass strain at the time of forming the straight portions 4f, 4f into bent portions can be reduced, and the thus formed straight portion can be easily and smoothly formed, thereby improving yielding in manufacture of the arc tube 4.
Further, in this embodiment, there is provided an example in which the paired straight portions 4f, 4f are formed at the of the half peripheral portion (about 180 degrees) from both ends Oa1, Oa2 of the maximum-diameter portion 6e, but the present invention is not limited to such example, and the paired straight portions 4f, 4f may be formed by bending the bulb end portion in the range of the central angle of 270 degrees (¾ peripheral length of the spiral shape) or 90 degrees (¼ peripheral length of the spiral shape).
According to the lighting apparatus 11 of this embodiment, since the spiral portion 4e of the compact fluorescent lamp 1, having high light flux and high luminous efficacy, faces downward in
In addition, the straight portions 4f that increase the light flux to be radiated toward the base 2 of the compact fluorescent lamp 1 is positioned adjacent to the reflector 14 of the lighting fixture body 12 to face the reflector 14, and it is therefore possible to increase the light to be reflected by the reflector 14.
It is to be noted that the present invention is not limited to the described embodiments and many other changes and modifications may be made without departing from the scopes of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-152671 | May 2006 | JP | national |
