Information
-
Patent Grant
-
6525455
-
Patent Number
6,525,455
-
Date Filed
Thursday, September 7, 200023 years ago
-
Date Issued
Tuesday, February 25, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Patel; Nimeshkumar D.
- Clove; Thelma Sheree
Agents
- Parkhurst & Wendel, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 313 31804
- 313 31803
- 313 31801
- 313 317
- 313 312
- 439 611
- 439 612
- 439 613
- 439 614
- 439 615
- 220 21 R
- 220 22
-
International Classifications
-
Abstract
To provide a bulb-form lamp including a few compartments, which can be easily fitted in a socket of a lighting equipment and reliably carry out electrical contact between a shell and the socket of the lighting equipment. The bulb-form lamp includes a shell surrounding one end of a casing, and the shell is molded integrally with one end of the casing to make contact with an outer surface of the casing leaving substantially no gap.
Description
FIELD OF THE INVENTION
The present invention relates to a bulb-form lamp and its manufacturing method.
BACKGROUND OF THE INVENTION
A conventional bulb-form lamp, for example, a compact self-ballasted fluorescent lamp accommodates a light generating tube
4
and a lighting circuit
5
for lighting the light generating tube
4
, in an envelope
29
including a globe
1
and a casing
28
, as shown in FIG.
12
.
In one end of the casing
28
, a cap
30
is inserted and caulked to be fixed. The cap
30
has a screw-shaped shell
31
screw and an eyelet
33
provided at one end of the shell
31
via a glass insulting part
32
. The shell
31
, the insulting part
32
and the eyelet
33
are integrally formed by embedding each part of the shell
31
and the eyelet
33
in the insulating part
32
.
Japanese Patent Laid-Open No. 9-97589 specification discloses another compact self-ballasted fluorescent lamp including a holder member (a casing) provided with a screw cap on an outer periphery of a cylindrical part formed at its one end. The screw cap is provided with a longitudinally formed recess, in which a feeding terminal forming a strip-shaped side terminal is provided.
However, such a conventional bulb-form lamp, for example, the compact self-ballasted fluorescent lamp shown in
FIG. 12
, has a problem that the casing
28
and the cap
30
are separately manufactured and then assembled together, resulting in many steps in process and low productivity efficiency.
In addition, a socket of a lighting equipment wherein the conventional compact self-ballasted fluorescent lamp is fitted, has been increasingly provided with a strip-shaped lamp holder for contact with the shell
31
or the feeding terminal.
In case where the compact self-ballasted fluorescent lamp disclosed in Japanese Patent Laid-Open No. 9-97589 specification is fitted in such a socket with the strip-shaped lamp holder, there is a problem that the strip-shaped lamp holder and the strip-shaped feeding terminal readily catch against each other, failing in fitting of the lamp in the socket. Another problem is that the lamp holder and the feeding terminal do not attain right positioning for contact therebetween, failing in lighting.
The present invention is achieved for solving such problems to provide a bulb-form lamp, including a few components and manufactured at low cost, which can be easily fitted in a socket of a lighting equipment and ensure electrical contact between the shell and the socket of the lighting equipment.
The present invention also provides a bulb-form lamp manufacturing method which enables reduction in the number of steps and improvement in productivity.
SUMMARY OF THE INVENTION
A bulb-form lamp according to the present invention has a configuration including a shell surrounding one end of a casing, the shell being molded integrally with one end of the casing to make contact with an outer surface of the casing leaving substantially no gap.
By such a configuration as including a few components and being able to be manufactured at a low cost, for example, when the shell is fitted in a socket of a lighting equipment having a strip-shaped lamp holder, the shell does not catch against the lamp holder so that it can be easily fitted in the socket and that the shell can make electrical contact with the lamp holder wherever the lamp holder is.
A bulb-form lamp manufacturing method according to the present invention uses a method for molding the shell integrally with one end of the casing leaving substantially no gap at the same time as molding the casing by using a die assembly.
Such integral molding of the shell with the casing when the casing is being molded eliminates the need for each conventional manufacturing step of the casing and the cap, and a step for assembling thereof, resulting in reduction in the number of steps.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a partly fragmentary front view of a compact self-ballasted fluorescent lamp according to a first embodiment of the present invention;
FIG. 2
is a partly fragmentary front view of a compact self-ballsted fluorescent lamp using another eyelet;
FIG. 3
is a perspective view of a shell member for forming a shell of the compact self-ballasted fluorescent lamp;
FIG. 4
is a view showing a method of manufacturing a casing used for the compact self-ballasted fluorescent lamp;
FIG. 5
is a view showing a method of manufacturing a casing used for the compact self-ballasted fluorescent lamp;
FIG. 6
is an enlarged sectional view of a casing used for the compact self-ballasted fluorescent lamp;
FIG. 7
is a sectional view of another shell member for forming the shell of the compact self-ballasted fluorescent lamp;
FIG. 8
is a view showing a method of manufacturing a casing at the time of using another shell member, in the compact self-ballasted fluorescent lamp;
FIG. 9
is a partly fragmentary front view of a compact self-ballasted fluorescent lamp according to a second embodiment of the present invention;
FIG. 10
is a sectional view of a shell member for forming a shell of the compact self-ballasted fluorescent lamp;
FIG. 11
is a partly fragmentary front view of a compact self-ballated fluorescent lamp according to a third embodiment of the present invention; and
FIG. 12
is a partly fragmentary front view of a conventional compact self-ballasted fluorescent lamp.
DESCRIPTION OF THE EMBODIMENTS
Embodiments of the present invention will be described below with reference to the drawings.
A compact self-ballasted fluorescent lamp with rated power of 13W according to a first embodiment of the present invention has overall length of 120 mm and maximum outer diameter of 60 mm. As shown in
FIG. 1
, an envelope
3
including a translucent globe
1
and a resinous casing
2
accommodates a fluorescent tube
4
, in which three U-shaped tubes
4
a
with outer diameter of 11 mm are bridge jointed to form a single discharge passage, a lighting circuit
5
for lighting the fluorescent tube
4
, and a holder
6
holding the lighting circuit
5
at a side opposite from the fluorescent tube
4
.
At one end of the casing
2
, a cap
7
is formed which is to be fitted in a socket of a lighting equipment (not shown), having a length of 27 mm and the maximum outer diameter of 26.4 mm.
The cap
7
includes a shell
8
formed with screw threads at its side, an eyelet
9
, and part of the casing
2
insulating the shell
8
and the eyelet
9
.
The shell
8
and the eyelet
9
are made of copper, brass, iron, stainless, nickel or the like, and their surfaces are coated with tin, zinc, nickel or the like for rustproofing.
The shell
8
surrounds one end of the casing
2
, and is molded integrally with a side surface of one end of the casing
2
to make contact with an outer surface of the casing
2
leaving no gap. Accordingly, the outer surface of one end of the casing
2
is formed with screw threads along an inner surface of the shell
8
. The shell
8
is described above to be in contact with the outer surface of the casing
21
leaving no gap, when molded. However, because of the difference in thermal expansion coefficient between the shell
8
and the casing
2
, there are actually such cases that a very small gap (about 0.1 to 0.3 mm) appears partly (not all along) between the shell
8
and the casing
2
due to thermal contractions of the shell
8
and the casing
2
during the integral molding. In view of this fact, the shell
8
integrally molded with a side surface of one end of the casing
2
will hereinafter be expressed as to be in contact with the outer surface of the casing
21
“leaving substantially no gap.”
Further, the shell
8
is embedded at its both ends in the casing
2
. This permits tight fixing of the shell
8
to the casing
2
, thereby preventing the shell
8
from being twisted off the casing
2
. In this case, the above described effect can be obtained when at least one end of the shell
8
is embedded in the casing
2
.
In addition, each tip of both ends of the shell
8
is bent inwardly and outwardly from the shell
8
, respectively. This permits further tight fixing of the shell
8
to the casing
2
, thereby preventing the shell
8
from being off the casing
2
. In this case, the above described effect can be obtained when the tip of at least one end of the shell
8
embedded in the casing
2
is bent inwardly or outwardly from the shell
8
.
Furthermore, at the tips of both ends of the shell
8
embedded in the casing
2
, a plurality of below-mentioned cut-out portions
15
a
,
15
b
are provided as shown in FIG.
3
. This improves rotational strength of the shell
8
when the cap
7
is fitted in or removed from the socket of the lighting equipment, thereby preventing lost motion of the shell
8
. In this case, the above described effect can be obtained when the cut-out portion
15
a
(
15
b
) is provided at the tip of at least one end of the shell
8
embedded in the casing
2
.
The eyelet
9
is formed from disk plate with thickness of 0.1 to 0.2 mm and molded integrally with one end of the casing
2
to make contact with the outer surface of the casing
2
leaving substantially no gap. In addition, a circumferential portion
9
a
of the eyelet
9
fitted in a periphery
9
b
of a below-mentioned through hole
11
is bent toward the casing
2
and embedded therein. This permits preventing the eyelet
9
from being off the casing
2
.
Electrodes (not shown) are provided at both ends of the fluorescent tube
4
, which is filled with predetermined amount of mercury and rare gas.
Two lead wires
10
a
and
10
b
, outer diameter of each conductor of 0.5 mm, are connected to the lighting circuit
5
for supplying electric power. One of the lead wires
10
a
is lead through the through hole
11
, provided by penetrating the eyelet
9
at its center together with the casing
2
, and connected to the outer surface of the eyelet
9
by soldering. The other lead wire
10
b
is lead through another through hole
12
, provided by penetrating the shell
8
at its end opposite from the eyelet
9
together with the casing
2
, and connected to the outer surface of the shell
8
by soldering.
In the above description, the eyelet
9
is used which is formed from a disk plate, part thereof being embedded in the casing
2
, as shown in
FIG. 1
; alternatively, an eyelet
13
may be used as shown in FIG.
2
.
The eyelet
13
is in the shape of a push-pin including a head
13
a
and a pin
13
b
. Provided at a tip of the pin
13
b
is a lead wire inserting portion
13
c
connected to a lead wire
10
a
. The eyelet
13
is made from the same material as the eyelet
9
.
In case of using the eyelet
13
, the structure of a tip of one end of the casing
14
is as shown in FIG.
2
. The casing
14
is provided, at the tip of its one end, with an eyelet receptacle
14
a
, inside of which has the same shape as outside of the eyelet
13
. The eyelet
13
is fitted to the eyelet receptacle
14
a.
Next, in the above described compact self-ballasted fluorescent lamp, a manufacturing method of the casing
14
will be described particularly in case of using the eyelet
13
shown in FIG.
2
.
As shown in
FIG. 3
, a blank member for forming the shell
8
(hereinafter referred to a shell member
15
) has a cylindrical shape with overall length of 23 mm, maximum outer diameter of 24 mm and thickness of 0.1 to 0.2 mm. Each of both ends of the shell member
15
is previously bent inwardly (see the upper side in
FIG. 3
) and outwardly (see the lower side in
FIG. 3
) from the shell member
15
, respectively. Besides, at the tips of both ends of the shell member
15
, a plurality of cut-out portions
15
a
and
15
b
are provided.
The casing
14
is molded by means of pouring liquid resin into below-mentioned dies.
As shown in
FIG. 4
, a first die
16
is arranged so as to surround the shell member
15
. The first die
16
is used for molding an outer shape of the casing
14
except the eyelet receptacle
14
a
shown in FIG.
2
. In addition, the first die
16
is provided, at a portion in contact with the shell
15
, with screw-shaped grooves
16
a
for molding screw threads on an outer surface of the shell member
15
.
A second die
17
is arranged at its part in the shell member
15
to mold an inner shape of the casing
14
.
A third
18
is arranged at a top of a portion where one end of the casing
14
is to be formed, in order to mold the eyelet receptacle
14
a
. The third die
18
is provided with a resin inlet
19
for pouring liquid resin
20
(not shown in FIG.
4
), which is material for the casing
14
such as polybutylene terephthalate, into a space formed by the first to the third dies
16
to
18
.
Subsequently, as shown in
FIG. 5
, the liquid resin
20
is poured from the resin inlet
19
into the space formed by the first to the third dies
16
to
18
to thereby fill the space. When pouring the liquid resin
20
, predetermined pressure is applied to the poured liquid resin
20
. By this pressure, part of the shell member
15
is expandingly forced into the screw-shaped grooves
16
a
of the first die
16
to be molded in the shape of the screw-shaped grooves
16
a
. Thus, the shell member
15
is molded to be the shell
8
in the shape of a screw.
Then, by caking the poured liquid resin
20
and thereafter removing the dies
16
,
17
and
18
, the casing
14
is manufactured, as shown in
FIG. 6
, which is integrally molded at its one end with the shell
8
formed with the screw threads at its side surface.
The both ends of the shell
8
including the bent portions and the cut-out portions
15
a
and
15
b
are arranged in the space formed by the first to the third dies
16
to
18
, and thereby embedded in the casing
14
after caking of the resin
20
.
In the above described first embodiment, description is made with respect to the manufacturing method of the casing
14
by using the eyelet
13
in the shape of a push-pin, as shown in FIG.
2
. In the case of the eyelet
9
, by changing the shape of the third die
18
, the casing
2
shown in
FIG. 1
can be manufactured by the same manufacturing method as described above.
It is preferable that a shell member
21
shown in
FIG. 7
is used as a blank member for forming the shell
8
. The shell member
21
has a cylindrical shape, with overall length of 23 mm, maximum outer diameter of 24 mm and thickness of 0.1 to 0.2 mm. Each of both ends of the shell member
21
is bent inwardly (see the upper side in
FIG. 7
) and outwardly (see the lower side in
FIG. 7
) from the shell member
21
, respectively. Besides, provided at an end of the shell member
21
is a circumferential groove
22
with width of 1.0 mm and depth of 0.5 mm.
The reason for preferably using the shell member
21
will be mentioned below.
As shown in
FIG. 8
, in case of pouring the liquid resin
20
into the space formed by the dies in order to die the casing
14
, when dieing the screw threads on a side surface of the shell member
21
by applying pressure to the liquid resin
20
, the portion of the shell member
21
where the screw threads are to be molded is pressed in A direction in
FIG. 8
, thereby a periphery of the portion is stretched in B direction in FIG.
8
. The periphery, however, is stretched little in the B direction. As a result, the portion of the shell member
21
where the screw threads are to be molded is stressed, which causes crack in the screw threads of the shell member
21
.
In this case, by using the shell member
21
provided at its end with the circumferential groove
22
, even if the periphery of the portion of the shell member
21
where the screw thread is to be molded is stretched in the B direction, an opening of the groove
22
spreads, which enables absorbing stress occurring in the portion, resulting in preventing the screw threads of the shell member
21
from being cracked.
Like the shell member
15
, the shell member
21
may be provided at its tips of both ends with a plurality of cut-out portions
15
a
and
15
b.
As described above, the shell
8
is molded integrally with one end of the casing
2
or
14
to make contact with the outer surface of the casing
2
or
14
leaving substantially no gap. According to this configuration including a few components and manufactured at low cost, for example, when fitted in the socket of the lighting equipment having a strip-shaped lamp holder, the shell
8
does not catch against the lamp holder so that it can be easily fitted in the socket and that the shell
8
can make contact with the lamp holder wherever it is in the socket, which means that certain electrical contact can be obtained between the shell
8
and the socket.
By using the manufacturing method for molding the casing
2
or
14
by the dies at the same time as molding the shell
8
integrally with one end of the casing
2
or
14
leaving substantially no gap, the shell
8
is molded integrally with the casing
2
or
14
at the same time as molding of the casing
2
or
14
, thereby eliminating the need for each conventional manufacturing step of the casing and the cap, and a step for assembling thereof, thereby reducing the number of steps, resulting in further improvement in production efficiency.
Particularly, by applying pressure on the material of the casing
2
or
14
poured into the space formed by the first to the third dies
16
to
18
at the same time as molding the casing
2
or
14
, the screw threads are formed on the side surface of the blank member for forming the shell
8
, thereby eliminating the need for a conventional separate step of forming the screw threads on the shell, resulting in further improvement in production efficiency.
In addition, particularly in case of using the eyelet
9
shown in
FIG. 1
, by using the above described method of molding the shell
8
integrally with the casing
2
or
14
at the same time as molding the casing
2
or
14
, the eyelet
9
is molded integrally with the tip of one end of the casing
2
leaving no gap, thereby omitting a step of fitting the eyelet
13
to the eyelet receptacle
14
a
in comparison with the case of using the eyelet
13
shown in
FIG. 2
, resulting in further improvement in production efficiency.
Next, a compact self-ballasted fluorescent lamp with rated power of 13W according to a second embodiment of the present invention has the same configuration as that according to the first embodiment except difference in structure of a shell
23
as shown in FIG.
9
.
The shell
23
has overall length of 23 mm, maximum outer diameter of 24 mm and thickness of 0.1 to 0.2 mm and is formed with screw threads at its side surface, molded integrally with the side surface of one end of the casing
2
to make contact with the outer surface of the casing
2
leaving substantially no gap.
The shell
23
is embedded at its both ends in the casing
2
in order to permit tight fixing of the shell
23
to the casing
2
and to thereby prevent the shell
23
from being off the casing
2
.
In addition, each tip of both ends of the shell
23
is bent inwardly and outwardly from the shell
23
, respectively, in order to permit further tight fixing of the shell
23
to the casing
2
.
Furthermore, at both ends of the shell
23
, a plurality of through holes
23
a
and
23
b
with diameter of 1 mm are provided, which are filled with part of the casing
2
.
As described above, the shell
23
is molded integrally with one end of the casing
2
to make contact with the outer surface of the casing
2
leaving substantially no gap. According to this configuration including a few components and manufactured at low cost, for example, when fitted in the socket of the lighting equipment having the strip-shaped lamp holder, the shell
23
does not catch against the lamp holder so that it can be easily fitted in the socket and that the shell
23
can make contact with the lamp holder wherever it is in the socket, which means certain electrical contact can be obtained between the shell
23
and the socket. Besides, filling the through holes
23
a
and
23
b
, provided on the shell
23
, with part of the casing
2
, though it is an easy step, improves rotational strength of the shell
23
when the cap
24
is fitted in or removed from the socket of the lighting equipment, thereby preventing lost motion of the shell
23
.
A blank member for forming the shell
23
(shell member
25
) is as shown in FIG.
10
.
In the above described second embodiment, description is made with respect to the case where the shell
23
is provided at its both ends with the through holes
23
a
and
23
b
. However, the above described effect can be obtained when the through hole
23
a
(the through hole
23
b
) is provided at the tip of at least one end of the shell
23
.
Next, a compact self-ballasted fluorescent lamp with rated power of 13W according to a third embodiment of the present invention has the same configuration as that according to the first embodiment of the present invention except difference in structure of a shell
26
as shown in FIG.
11
.
The shell
26
has overall length of 23 mm, maximum outer diameter of 24 mm and thickness of 0.1 to 0.2 mm and is formed with screw threads at its side surface, molded integrally with the side surface of one end of the casing
2
to make contact with the outer surface of the casing
2
leaving substantially no gap.
The shell
26
is embedded at its both ends in the casing
2
in order to permit tight fixing of the shell
26
to the casing
2
and to thereby prevent the shell
26
from being off the casing
2
.
In addition, each tip of both ends of the shell
26
is bent inwardly and outwardly from the shell
26
, respectively in order to permit further tight fixing of the shell
26
to the casing
2
.
Furthermore, at both ends of the shell
26
, a plurality of recesses
26
a
and
26
b
with length of 1 to 2 mm, width of 1 mm and depth of 0.5 mm are provided, which are filled with part of the casing
2
.
As described above, the shell
26
is integrally molded with one end of the casings
2
to make contact with the outer surface of the casing
2
leaving substantially no gap. According to this configuration including a few components and manufactured at low cost, for example, when fitted in the socket of lighting equipment having a strip-shaped lamp holder, the shell
26
does not catch against the lamp holder that it can be easily fitted in the socket and that the shell
26
can make contact with the lamp holder wherever it is in the socket, which means that certain electrical contact can be obtained between the shell
26
and the socket. Besides, filling the recesses
26
a
and
26
b
, provided on the shell
26
, with part of the casing
2
, though it is an easy step, improves rotational strength of the shell
26
when the cap
27
is fitted in or removed from the socket of the lighting equipment, thereby preventing lost motion of the shell
26
.
In the above described third embodiment, description is made with respect to the case where the shell
26
is provided at its both ends with the recesses
26
a
and
26
b
. However, the above described effect can be obtained when the recess
26
a
(the recess
26
b
) is provided at the tip of at least one end of the shell
26
.
In the above described each embodiment, descriptions are made with respect to the case of the compact self-ballasted fluorescent lamp. However, the above described effect can be obtained with respect to bulb-form lamps such as an incandescent lamp, a reflector lamp, a high-pressure discharge lamp or the like.
Further, in the above described each embodiment, descriptions are made in respect of the case where, in the lamp fitted in the socket of the lighting equipment, the portion to be fitted in the socket, namely, the caps
7
,
24
and
27
are formed with the screw threads at the side surfaces of the shell
8
,
23
and
26
. However, the above described effect can be obtained in case of using caps with no screw thread.
Claims
- 1. A lamp comprising:a casing having two ends and extending from a glass globe at one end to an eyelet at the other end; a shell surrounding a part of the casing having a portion for mounting an eyelet at one end thereof and a portion for mounting a holder at the other end thereof, wherein said shell is molded integrally with one end of said casing and is in contact with an outer surface of said casing leaving substantially no gap.
- 2. The lamp according to claim 1, wherein said shell further comprises screw threads at a side surface thereof.
- 3. The lamp according to claim 1, wherein at least one end of said shell is embedded in said casing.
- 4. The lamp according to claim 3, wherein a tip of an end of said shell is bent inwardly or outwardly from said shell.
- 5. The lamp according to claim 3, wherein a cut-out portion is located at a tip of an end of said shell embedded in said casing.
- 6. The lamp according to claim 1, wherein said shell further comprises a through hole filled with part of said casing.
- 7. The lamp according to claim 1, wherein said shell further comprises at least one end thereof with a recess filled with part of said casing.
- 8. The lamp according to claim 1, wherein said shell further comprises an eyelet molded integrally with a tip of said casing for contact with an outer surface of said casing, and no gap between said tip and said casing.
- 9. The lamp according to claim 1, wherein both ends of the shell are embedded in said casing.
Priority Claims (2)
Number |
Date |
Country |
Kind |
11-268633 |
Sep 1999 |
JP |
|
2000-206493 |
Jul 2000 |
JP |
|
US Referenced Citations (8)