Information
-
Patent Grant
-
6762550
-
Patent Number
6,762,550
-
Date Filed
Monday, December 23, 200221 years ago
-
Date Issued
Tuesday, July 13, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Patel; Vip
- Zimmerman; Glenn
-
CPC
-
US Classifications
Field of Search
US
- 313 160
- 313 161
- 313 573
- 313 493
- 313 44
- 313 634
- 315 248
- 315 344
-
International Classifications
-
Abstract
An electrodeless discharge lamp with a first coupling member includes a translucent discharge vessel in which a discharge gas is enclosed. A bobbin that includes a coil holding part for an induction coil and a vessel mounting part with a second coupling member is formed as a single piece. The coil holding part holds the induction coil on an outer surface thereof and is placed in proximity to the discharge vessel. The first and second coupling members are complementary and engage to mount the discharge vessel on the vessel mounting part of the bobbin to assure a long life and a positioning accuracy of the discharge vessel and the induction coil thereof.
Description
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an electrodeless discharge lamp that does not include an electrode inside its discharge vessel.
(2) Related Art
These days have seen an increasing use of electrodeless discharge lamps, because of their excellent energy efficiency and long lifespan. The electrodeless discharge lamps are broadly divided into two types: electrodeless fluorescent lamps and high intensity discharge lamps (H.I.D.). In the following, an electrodeless fluorescent lamp is taken as an example, and the structure thereof is described.
In an electrodeless fluorescent lamp, a discharge vessel is placed to be in the proximity of an induction coil, the induction coil being provided on a circuit substrate in an upright position. The discharge vessel is translucent and in which a discharge gas made of a rare gas and mercury is enclosed, and the circuit substrate is stored inside a case so as to be avoided contact of human hands while the lamp is being used.
In most cases, the discharge vessel and the circuit substrate are both attached to the case. In particular, the discharge vessel is attached to the case, with a layer made of heat-resistance silicone in-between.
The silicone used for attaching the discharge vessel to the case will gradually deteriorate; for the silicone layer is subject to the heat from the discharge vessel, when the lamp emits light. Therefore, since electrodeless fluorescent lamps have a significantly longer lifespan compared to conventional fluorescent lamps that have an electrode in their discharge vessel, it is hard for the silicone layer of electrodeless fluorescent lamps to maintain a bonding strength between the discharge vessel and the case, until the last stage of the lifespan. Accordingly, it sometimes happens that the discharge vessel falls off from the case.
In addition, the electrodeless fluorescent lamp described in the above has a structure in which the discharge vessel is coupled to the induction coil, through the mediation of the circuit substrate, the case, and the like. According to this structure, assembly variations will occur at the time of assembling the parts together, besides the variations of size for individual parts. Accordingly, it sometimes happens that the position between the discharge vessel and the induction coil deviates from as designed. When the relative position between the discharge vessel and the induction coil deviates, the problem arises that the luminous performance differs according to an area of the discharge vessel.
A technology has been proposed by the Japanese Laid-open Patent Application No. H09-320541 for coping with the above mentioned problem. In this patent application, a case is provided with a convex portion that is used to couple the discharge vessel to the case; and a corresponding concave portion is provided on the corresponding area of the discharge vessel. The discharge vessel will be coupled to the case, by fitting the convex portion to the concave portion.
For the electrodeless fluorescent lamp produced using the above technology, the discharge vessel will be prevented from falling off at the later stage of lifespan, and the deviation in relative position between the discharge vessel and the case is reduced to a minimum.
However, in the method of coupling the discharge vessel to the case, in order to fit the convex portion to the concave portion, a force is to be exerted on the discharge vessel and on the case. This means that a force will be exerted on a discharge vessel which is made of glass. For assuring strength and accuracy in mounting the discharge vessel to the case, it becomes necessary to have a smaller clearance between the concave portion and the convex portion, which further increases a force that the discharge vessel is subject to. In some cases, this leads to a break of the discharge vessel or the case.
As mentioned in the above, for the electrodeless fluorescent lamp produced using the disclosed technology, the accuracy in position between the discharge vessel and the case is assured; however, the accuracy in position between the discharge vessel and the induction coil (which is an important factor in assuring the uniform luminous performance throughout the entire luminous area) will not be assured. This is due to the structure of this electrodeless fluorescent lamp, in which its discharge vessel and induction coil are attached to each other, through a mediation such as the circuit substrate and the case. Therefore, the positioning accuracy of the discharge vessel and the induction coil will be hindered, as much as an accumulation of various kinds of deviations yielded at the time of producing and assembling the mediation parts.
Considering the above, it can be said that the disclosed technology is not for practical use.
SUMMARY OF THE INVENTION
The object of the present invention, in order to solve the stated problems, is to provide an electrodeless fluorescent lamp whose discharge vessel is prevented from falling off, and that delivers a uniform luminous performance throughout the entire luminous area by assuring an accuracy in position between a discharge vessel and an induction coil.
In order to achieve the above object, the electrodeless discharge lamp of the present invention is characterized by having a translucent discharge vessel in which a discharge gas is enclosed, the discharge vessel having a first coupling member; an induction coil; and a bobbin that includes a coil-holding part and a vessel-mounting part that are formed as a single piece, the vessel-mounting part having a second coupling member, where the coil-holding part holds the induction coil on an outer surface thereof, and is placed in a proximity of the discharge vessel, and the first coupling member and the second coupling member are coupled so as to mount the discharge vessel on the vessel-mounting part of the bobbin.
The electrodeless discharge lamp according to the present invention has a discharge vessel that is mechanically coupled by the second coupling member of the vessel-mounting part. Accordingly, the discharge vessel will be prevented from falling off, over a long period of time.
In addition, in the above-mentioned conventional electrodeless discharge lamp, it is difficult to maintain a positioning accuracy between its discharge vessel and induction coil, since the discharge vessel and the induction coil are coupled to each other, with a plurality of parts in-between. Whereas in the electrodeless discharge lamp of the present invention, the coil-holding part and the vessel-mounting part are formed as a single piece, where the coil-holding part holds the induction coil, and the vessel-mounting part coupling the discharge vessel to the bobbin. According to the above structure, the electrodeless discharge lamp of the present invention realizes a high positioning accuracy between the discharge vessel and the induction coil in the mounting process. At the same time, the relative position between the discharge vessel and the induction coil will not vary, according to a heat generated from the discharge vessel at the time of the lamp being used.
Accordingly, the electrodeless discharge lamp according to the present invention will assure a uniform luminous performance throughout its luminous area, and will not be subject to a damage that would happen due to the induction coil coming in contact with the discharge vessel during the transportation of the lamp, between the shipping of the lamp to the setting thereof, for example.
In the stated electrodeless discharge lamp, it is desirable to have a structure in which one of the first coupling member and the second coupling member is a protrusion, and the other is a groove that is shaped to receive the protrusion is desirable, in order to produce the lamp with ease, and that to mount the discharge vessel with a high positioning accuracy.
In the stated electrodeless discharge lamp, the discharge vessel is desirably coupled to the vessel-mounting part so that the discharge vessel is held in a fixed position, in order to further increase the positioning accuracy between the discharge vessel and the induction coil.
In the stated electrodeless discharge lamp may further have the following structures: a structure in which a distance between a groove bottom and a center of the vessel-mounting part continuously decreases in a diameter direction, the groove bottom being a part of an inner surface of the bottom that is under the groove, and the protrusion of the discharge vessel is guided toward a center of the vessel-mounting part in a diameter direction by being rotated along the groove bottom, so as to eventually hold the discharge vessel in a fixed position; and a structure in which the groove is formed along the inner wall so as to continuously decrease in height, and the protrusion of the discharge vessel is guided toward a height direction of the groove formed on the vessel-mounting part, by being rotated along the part of the inner wall, so as to eventually hold the discharge vessel in a fixed position. These structures are desirable in view of assuring the positioning accuracy between the discharge vessel and the induction coil. These structures are also advantageous in that a large force is not necessary in coupling the discharge vessel.
Here, the discharge vessel may be rotated leftward when the vessel-mounting part is seen from the discharge vessel. This is an opposite direction to the rightward direction in which the lamp is rotated when setting the lamp.
Generally speaking, in taking off the electrodeless discharge lamp at the last stage of its lifespan, the lamp is made to be loose, by rotating the lamp in a leftward direction. Considering the above, it is advantageous to couple the discharge vessel by a leftward rotation, since at the time of taking off the lamp having ended its life through a leftward rotation, the discharge vessel will be further fastened to the vessel-mounting part. This will prevent the discharge vessel from falling off from the vessel-mounting part.
In the above described electrodeless discharge lamp, the discharge vessel may be held in a fixed position, by being directly coupled to the vessel-mounting part, or by means of a member made of a resin material in-between, such as silicone and epoxy.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings that illustrate a specific embodiment of the invention. In the drawings:
FIG. 1
is an exploded perspective view of an electrodeless fluorescent lamp
1
that relates to the first embodiment;
FIG. 2
is a perspective diagram of the discharge vessel shown in the above
FIG. 1
;
FIG. 3
is an exploded view showing how a bobbin, a ferrite core, and a heat sink member are linked;
FIG. 4
shows a perspective view of the bobbin;
FIG. 5
shows a fragmentary sectional view of a vessel-mounting part that is taken along the line A—A;
FIG. 6
is a diagram showing a general view of the electrodeless fluorescent lamp after having been assembled, (a part of which is a sectional view to show inside); and
FIG. 7
is a diagram showing a general view of an electrodeless fluorescent lamp according to the second embodiment (a part of which is a sectional view to show inside).
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(The First Embodiment)
The first embodiment of the present invention is described in the following, with reference to FIG.
1
.
FIG. 1
is an exploded perspective view of an electrodeless fluorescent lamp
1
which relates to the first embodiment. As shown in
FIG. 1
, the electrodeless fluorescent lamp
1
of the first embodiment is made up of a discharge vessel
10
, a bobbin
20
to which a heat sink member
30
is fixed, and a case
40
.
The bobbin
20
includes a coil-holding part
21
and a vessel-mounting part
22
that are formed as a single piece using one resin material. The coil-holding part
21
is in a tubular shape and holds an induction coil
36
, and the discharge vessel
10
is coupled to the vessel-mounting part
22
. The heat sink member
30
is fixed to one surface of the vessel-mounting part
22
, the surface being opposite to the other surface from which the coil-holding part
21
outstands.
Further, the coil-holding part
21
is inserted into a hollow
13
(not shown in
FIG. 1
, see FIG.
2
), the hollow
13
being provided in the center of the discharge vessel
10
.
The heat sink member
30
is integrally formed with a core-supporting member
31
in a tubular form and a base member
32
, both of which are made of a metal material. The heat sink member
30
is fixed to the bobbin
20
in such a manner that the core-supporting member
31
is inserted into the coil-holding part
21
. The heat sink member
30
is used for liberating heat from the ferrite core
35
(not shown in
FIG. 1
) and from the induction coil
36
, at the time when the lamp emits light.
On a surface of the base member
32
, which is opposite to the surface where the core supporting member
31
is provided to outstand, a circuit-mounted member is provided that includes a high frequency oscillating circuit and a rectifier, and the like. None of the circuit-mounted member, the high frequency oscillating circuit, and the rectifier is shown in FIG.
1
.
The case
40
is in a funnel-like shape, and covers the heat sink member
30
so that the circuit-mounted member is kept from contact of human hands while the lamp is used. At the lower end of the case
40
, a screw base
41
is fixed. The screw base
41
is used for fixing the lamp to a luminaire, and also for connecting the lamp to an external power source. The screw base
41
is made of an electrically conductive metal. On the surface area of the screw base
41
, a screw member (right-hand thread) is formed for fixing the lamp to the luminaire.
The bobbin
20
and the case
40
are fixed to each other, by fitting the convex portion
401
provided on an inner surface of the upper side of the case
40
, to the concave portion
228
provided on an outer surface of the side of the vessel-mounting part
22
.
The following is a description on the structure of the discharge vessel
10
, with reference to FIG.
2
.
As shown in
FIG. 2
, the discharge vessel
10
is substantially spherical in shape and is made of a translucent material. On the lower end part of the discharge vessel
10
, a neck portion
11
is formed which has a shorter diameter compared to the other parts of the discharge vessel
10
.
A hollow
13
is formed in a cylinder-like shape through the neck portion
11
of the discharge vessel
10
, and elongates toward the center of the discharge vessel
10
. Inside the hollow
13
, a thin tube portion
14
is formed to elongate toward an outside direction of the discharge vessel
10
(toward the lower direction in the example of FIG.
2
).
In addition, four protrusions
12
are respectively formed on four outside surface areas of the neck portion
11
, each protrusion
12
outstanding outwardly in the diameter direction of the discharge vessel
10
.
FIG. 2
shows two protrusions thereof.
The discharge vessel
10
has a phosphor layer on its inner wall (not shown in FIG.
2
). In the space inside the discharge vessel
10
, a discharge gas that is a mixture of mercury and a rare gas is enclosed.
For the discharge vessel
10
having the above structure, the protrusions
12
of the neck portion
11
are formed as follows: first, the neck portions
11
are heated up to the softening point, using a burner for example, then molds are placed to sandwich the neck portion
11
, the molds being shaped to have portions formed to correspond to the form of the protrusions
12
.
Next, the structure relating to the peripheral parts of the bobbin
20
, and the fixing of the heat sink member
30
to the bobbin
20
are described, with reference to FIG.
3
.
As shown in
FIG. 3
, a ferrite core
35
is inserted in a through-hole formed through the middle of the coil-holding part
21
, the ferrite core
35
being tube-shaped and having an outer diameter which is slightly smaller than the inner diameter of the through-hole of the coil-holding part
21
. Please note that a heat-resistance white tape (not shown in
FIG. 3
) is wound around the outer surface of the induction coil
36
that is held around the coil-holding part
21
, the outside surface of the induction coil
36
being which faces the inner wall of the hollow
13
when assembled. Thanks to this heat-resistance white tape, visible light converted by means of the phosphor layer will be prevented from being absorbed through the induction coil
36
inserted in the middle of the discharge vessel
10
, and is guided to the outside of the lamp.
Note that as long as the above effect is achieved, the heat-resistance white tape which is described in the above is replaceable with any means. For example, in order to reflect visible light, a white tube may be used to cover the induction coil
36
, or a heat-resistance white paint may be applied to the induction coil
36
so as to form a paint-layer. Examples of the materials which may be used therefor include: silicone, polytetrafluoroethylene, and poly-imide-amide.
In addition, the light-reflective layer may be also formed as follows, in place of applying the heat-resistant white paint. Firstly, powders made from such as alumina and silica are mixed with a binder, then the powders are applied to the surface of the induction coil
36
, and finally a layer is formed by firing the powders on the induction coil
36
.
Further, the core-supporting member
31
of the heat sink member
30
is inserted in a through-hole of the ferrite core
35
, the through-hole being formed through the middle of the ferrite core
35
in its diameter direction.
Although not shown in
FIG. 3
, for connecting the induction coil
36
with the circuit mounting member which is fixed to the heat sink member
30
, a lead wire (not shown in
FIG. 3
) is used which is inserted in a hole that is provided through the bobbin
20
and the base member
32
of the heat sink member
30
.
Next, the structure of the bobbin
20
which is a character part of the present invention is described, with reference to FIG.
4
.
In reality, the coil-holding part
21
and the vessel-mounting part
22
are formed as a single piece using a same resin material. Examples of the resin material are such as a polyphenylene sulfide (PPS) resin, and a liquid crystal polymer, that have a high heat-resistance.
As shown in
FIG. 4
, the vessel-mounting part
22
is a shallow dish which has a bottom and an upright brim portion. Four walls
221
are formed around the top surface of the brim portion of the shallow dish. Each wall
221
elongates toward inside of the diameter direction of the shallow dish. An outer surface of each wall portion is processed to be curved, so as to coincide with the curved form of the outer surface of the discharge vessel
10
.
As a result of the four walls
221
being formed, four grooves
224
are each formed between each of the walls
221
and the bottom surface
223
of the vessel-mounting part
22
.
In addition, four portions
222
are respectively cut away from between each neighboring wall
221
to form four cut-out portions
222
. The cut-out portions
222
are formed to enable the protrusions
12
to be freely inserted into the grooves
224
without being disturbed by the walls
221
, at the time when the coil-holding part
21
is inserted into the hollow
13
of the discharge vessel
10
, and the neck portion
11
of the discharge vessel
10
is inserted into the vessel-mounting part
22
of the bobbin
20
.
Further, both ends of each wall
221
, which are next to the cut-out portions
222
, are provided with a prevention wall
225
and a rising portion
226
, respectively. Each prevention wall
225
is formed to connect the bottom surface
223
and the wall
221
, and is formed at the left end of each wall
221
, when the bobbin
20
is seen in its plan view.
On the other hand, each rising portion
226
is formed under the right end of each wall
221
, when the bobbin
20
is seen in its plan view. The rising portion
226
outstands from the bottom surface
223
and has a height which is the same as the thickness of the protrusion
12
of the discharge vessel
10
, so as to prevent the discharge vessel
10
from being slipped off by reverse-rotation, after the discharge vessel
10
has been coupled to the vessel-mounting part
22
.
Around the outer side surface of the brim portion of the vessel-mounting part
22
, four concave portions
228
are formed, for fixing the case
40
, as mentioned in the above.
The following is a description of the specific form of the groove
224
, with reference to FIG.
5
.
FIG. 5
is a sectional view taken along the line A—A of
FIG. 4
, and shows a sectional view of the vessel-mounting part
22
, taken at a substantially middle portion of an summation of the height of the wall
221
and the thickness of the bottom portion (that includes the bottom surface
223
).
As shown in
FIG. 5
, the outer surface of the vessel-mounting part
22
is round in shape. In the middle of the vessel-mounting part
22
, a coil-holding part
21
that is in a tube-shape is formed.
As already mentioned, the prevention wall
225
and the rising portion
226
are formed on inside of the side wall of the vessel-mounting part
22
, both being elongated toward inward direction of the diameter.
A groove bottom
229
that is a part of the bottom surface
223
and is under the groove
224
is in a taper-like shape, so as to gradually reduce a clearance formed in a diameter direction between the protrusion
12
, at the time when the discharge vessel
10
is being rotated. The groove bottom
229
is formed so that the clearance will disappear at a place where the side surface of the protrusion
12
of the discharge vessel
10
comes into collision with the prevention wall
225
.
The following describes how the discharge vessel
10
is coupled to the vessel-mounting part
22
that has the above structure.
First, the coil-holding part
21
of the bobbin
20
is inserted into the hollow
13
of the discharge vessel
10
, until the protrusion
12
of the discharge vessel
10
reaches the groove
224
. Note here, that the protrusion
12
has to pass through the cut-out portion
222
, before reaching the groove
224
. In addition, the depth that the discharge-vessel
10
should go in the bobbin
20
is deeper than the wall
221
, and shallower than the upper surface of the rising portion
226
.
Next, the discharge vessel
10
is rotated in the leftward direction, until the protrusion
12
passes through the rising portion
226
, then a bottom surface of the protrusion
12
of the discharge vessel
10
is fitted to the bottom surface
223
of the vessel-mounting part
22
(the bottom surface
223
not shown in FIG.
5
).
Further, the discharge vessel
10
is rotated in the leftward direction, while keeping the bottom surface of the protrusion
12
fitted to the bottom surface
223
of the vessel-mounting part
22
. As the discharge vessel
223
rotates, a protrusion
12
that positions farthest in the diameter direction comes into contact with the groove bottom
229
, and slides along the groove bottom
229
. By this process, the protrusion
12
is guided, along the groove bottom
229
, toward the center in the diameter direction of the vessel-mounting part
22
. Eventually, the centering between the discharge vessel and the vessel-mounting part
22
is realized as a result of all the four protrusions
12
coming into contact with the respective groove bottoms
229
. By this process, the position of the discharge vessel
10
relative to the bobbin
20
in the diameter direction is determined with high level of accuracy.
Further, as also for the height direction, the position of the discharge vessel
10
relative to the vessel-mounting part
22
is determined with reliability, since the protrusion
12
is fitted to the bottom surface
223
of the vessel-mounting part
22
, while the protrusion
12
is being rotated.
In the above way, the discharge vessel
10
will be finally caught by the vessel-mounting part
22
, by being rotated until the side surface of the protrusion
12
comes into collision with the prevention wall
225
. At this moment, the clearance between the protrusion
12
of the discharge vessel
10
and the groove bottom
229
of the groove
224
disappears, as already mentioned. In other words, the groove bottom
229
of the groove
224
is formed so as to cease to have a clearance between the protrusion
12
, when the side surface of the protrusion
12
comes into collision with the prevention wall
225
.
Here, it is important to make sure that the discharge vessel
10
is coupled, by being rotated until the protrusions
12
come into collision with the respective prevention walls
225
. However, in the coupling process, care should be taken so as not to impose too much stress on the discharge vessel
10
. That is, it is desired that the characteristic value for the strength of the discharge vessel
10
is known in advance, so as to be able to perform coupling with the adequate torque calculated based on the value. If the torque generated at the time of rotation is too large, the discharge vessel will be subject to too much stress, while if the torque is too small, a large clearance is generated between the discharge vessel
10
and the vessel-mounting part
22
, which will lead to an inaccurate positioning therebetween.
Note here that the torque will vary depending on the material and the thickness. Therefore individual adjustment is required.
In a clearance generated between the discharge vessel
10
and the vessel-mounting part
22
, which have been mechanically coupled to each other, heat-resistant silicone is injected and then heated, so as to form a silicone layer
51
(refer to FIG.
6
). The silicone layer
51
helps fix the discharge vessel
10
to the vessel-mounting part
22
, with reliability. The silicone layer
51
also plays a role of avoiding an entry of the water into the area that is provided with the induction coil
36
.
As shown in
FIG. 6
, the case
40
is fixed to the vessel-mounting part
22
, after the discharge vessel has been coupled to the vessel-mounting part
22
. A heat-resistance silicone layer
52
is also formed in a gap generated between the vessel-mounting part
22
and the case
40
. The reason why the silicone layer
52
is formed in this place is to prevent an entry of water and the like in the case
40
, in an attempt to prevent a short and the like that would otherwise occur on the circuit substrate that is fixed to the heat sink member
30
.
The wirings
61
and
62
are provided so as to connect the screw base
40
of the case
40
with the circuit substrate of the heat sink member
30
.
(Excellence of the Electrodeless Fluorescent Lamp
1
)
Usually, a clearance is formed between the hollow
13
of the discharge vessel
10
and the coil-supporting member
21
of the bobbin
20
. However, in the electrodeless fluorescent lamp
1
, the discharge vessel
10
is coupled to the bobbin
20
with high positioning accuracy. Therefore, the hollow
13
will not come into contact with the coil-supporting member
21
, at the time of transporting the lamp, for example. Accordingly, the hollow
13
and the thin tube portion
14
will be avoided from being damaged.
Furthermore, in conventional electrodeless fluorescent lamps, a discharge-vessel is attached to the case by means of an adhesive and the like. This makes it difficult, in the production process, to assure accuracy in positioning between the induction coil and the discharge vessel. Accordingly, the luminous performance tends to differ according to each luminous area of the lamp. Further, with conventional electrodeless fluorescent lamps, it sometimes happened that the phosphor layer formed inside the hollow that is created in the middle of the discharge vessel
10
tends to change its color into black (i.e. solarization), which is due to the hollow being too close to induction coil.
The electrodeless fluorescent lamp
1
in the above can coop with the stated problems by the structure of mechanically coupling the discharge vessel
10
and the bobbin
20
. As a result, the high accuracy in positioning between the discharge vessel
10
and the induction coil
36
is achieved, which realizes a uniform luminous performance throughout the entire luminous area.
Further, from the same reason, for the electrodeless fluorescent lamp
1
, the discharge-vessel
10
is avoided from falling off, which would occur due to the deterioration of the silicone layer after the lamp has been used over a long time.
In addition, for the electrodeless fluorescent lamp
1
, while turning the lamp in a leftward direction, so as to remove the lamp from the luminaire at the end of the life of the lamp, the discharge vessel
10
will remain tightened to the bobbin
20
, since the discharge vessel
10
is coupled to the bobbin by a leftward rotation. Therefore, the discharge vessel
10
will not fall off from the bobbin
20
. This means that the electrodeless fluorescent lamp is excellent in safety point of view at the time of operation.
(The Second Embodiment)
In the first embodiment described above, the electrodeless fluorescent lamp
1
has an excellent characteristics in assembly accuracy, safety level in operating the lamp, and the like, by having the structure of mechanically coupling the discharge vessel
10
directly to the vessel-mounting part
22
of the bobbin
30
. In the following, the electrodeless fluorescent lamp
2
is described that is assured to have a high assembly accuracy without being susceptible to the forming accuracy of the discharge vessel
10
, with reference to FIG.
7
.
The difference between the electrodeless fluorescent lamp
2
of FIG.
7
and the electrodeless fluorescent lamp
1
in the first embodiment is in the form of a bobbin
26
, in particular in the form of a vessel-mounting part
23
. Accordingly, the same reference numbers are used for the other parts that are the same as those in the first embodiment, and the explanation thereof will not be done in the present embodiment.
As shown in
FIG. 7
, the vessel-mounting part
23
is formed a wall
231
that extends from an upper portion of the side wall thereof, so as to form a groove
234
which is wider than that of the vessel-mounting part
22
. The distance from the bottom surface
233
to the wall
231
, (i.e. the height of the groove
234
) may either be the same as, or larger than the height of the groove
224
of the electrodeless fluorescent lamp
1
.
Clearances d1, d2, and d3 are formed between the protrusion member
12
of the discharge vessel
10
and the groove
234
of the vessel-mounting part
23
. A heat-resistance silicone layer
53
is provided in each of the clearances d1, d2, and d3. Through this silicone layer
53
, the discharge vessel
10
is coupled to the vessel-mounting part
23
. Here, note that the silicone layer
53
is formed inside the vessel-mounting part
23
wherever it has a clearance between the discharge vessel
10
and the vessel-mounting part
23
. However, the clearances d1, d2, and d3 do not have to be formed to be even, along the vessel-mounting part
23
, as long as a predetermined position is maintained between the discharge vessel
10
and the induction coil
36
.
The coupling of the discharge vessel
10
to the vessel-mounting part
23
is concretely performed as follows.
First, the protrusions
12
of the discharge vessel
10
is inserted into the groove
234
of the vessel-mounting part
23
, until the side surface of the protrusion
12
comes into collision with a prevention wall
225
(the prevention wall
225
not shown in FIG.
7
). Up to now, the procedure is the same as the one explained in the first embodiment, and the discharge vessel
10
is also rotated in a leftward direction as the first embodiment. However, the discharge vessel
10
in the present embodiment will not be held in a fixed position even when the side surface of the protrusion
12
comes into collision with the prevention wall
225
. That is, the protrusion
12
of the discharge vessel
10
will be in such a condition that there is a clearance in every four direction in relation to the inner wall of the groove
234
, even when the side surface of the protrusion
12
comes into collision with the prevention wall
225
.
Next, the discharge vessel
10
and the bobbin
26
are respectively held by means of cramps for example. The cramps are then moved so that the induction coil
36
held by the coil-holding part
21
is placed in a predetermined position in relation to the hollow
13
of the discharge vessel
10
. Such position arrangement of the induction coil
36
and the discharge vessel
10
is made possible thanks to the clearance generated between the protrusion
12
and the wall of the groove
234
.
Finally, while maintaining the above positioning of the induction coil
36
in relation to the hollow
36
, a heat resistance silicone is injected through a clearance generated between the neck portion
11
of the discharge vessel
10
(not shown in
FIG. 7
) and the wall
231
of the vessel-mounting part
23
, then heated to be hardened. As a result, a silicone layer
53
is formed, through which the discharge vessel
10
and the bobbin
26
are held in a fixed position to each other.
In the above way, even when there are variations in sizes for the discharge vessel
10
or for the bobbin
26
, such variation will be absorbed by the clearances d1, d2, and d3 generated between the protrusion
12
and the groove
234
. This will realize coupling between the induction coil
36
and the discharge vessel
10
, with high positioning accuracy. In particular, the discharge vessel
10
, being produced by heating glass, has a greater possibility of generating variations in size, compared to the other parts. Therefore the electrodeless fluorescent lamp
2
that has the above-described structure is excellent in terms of achieving positioning accuracy between the induction coil
36
and the hollow
13
of the discharge vessel
10
.
Therefore, it can be said that the electrodeless fluorescent lamp
2
compares favorably with the electrodeless fluorescent lamp
1
in that the electrodeless fluorescent lamp
2
also achieves such as the uniform luminous performance, superior level of safety, just as the electrodeless fluorescent lamp
1
. In particular, the electrodeless fluorescent lamp
2
attains a constant luminous performance without depending on variations in sizes of the discharge vessel
10
.
In addition, the production of the electrodeless fluorescent lamp
2
allows a wider range of sizes in parts, compared to the production of the electrodeless fluorescent lamp
1
, since the clearances d1, d2, and d3 are able to absorb the variations in size of the discharge vessel
10
, the bobbin
26
, and the other parts. That is, the electrodeless fluorescent lamp
2
will need only a minimum level of size accuracy in the production of the parts, which is an advantage in terms of productivity, as well as from a cost point of view.
Further, the electrodeless fluorescent lamp
2
has a silicone layer
53
between the discharge vessel
10
and the bobbin
26
. This is another excellent feature that it has insulation reliability, compared to such lamps as the electrodeless fluorescent lamp
1
in which the parts have been directly coupled.
Note that for the bobbin
26
already mentioned, the groove bottom
229
may be formed in a taper shape as shown in
FIG. 5
, or may not be formed in a taper shape. Likewise, the width direction of the groove
234
(i.e. height direction in
FIG. 7
) may be formed in a taper shape, or may not.
In addition, in the above description, a silicone layer
53
as a thermosetting resin layer is provided in a passage formed between the discharge vessel
10
and the vessel-mounting part
23
. However, the layer to be provided in such passage is not confined to a layer made of silicone; a layer made of such as epoxy resin will also work.
(Other Things to Remember)
Note that in both of the first and second embodiments, only one type of electrodeless fluorescent lamps is taken as one example. However, the present invention is also applicable to electrodeless discharge lamps in general, such as electrodeless fluorescent lamps whose induction coil is formed on an outer surface of the discharge vessel, and high intensity discharge lamps (H.I.D.).
Furthermore, in the above description, the electrodeless fluorescent lamp
1
taken as an example includes the bobbin
20
that is made of a polyphenylene sulfide (PPS) resin, and a mixture of mercury and a rare-gas is enclosed in its discharge vessel. However, not to mention, the mentioned features are not essential to the present invention.
Furthermore, in the above embodiments, the circuit mounting member is mounted to the heat sink member
30
. However, the mounting place may be at the undersurface of the bobbin
20
, or of the bobbin
26
. Or, the circuit mounting member and the bobbin
20
(or the bobbin
26
) may be formed as a single piece.
In the above described electrodeless fluorescent lamp
1
, the groove bottom
229
in the vessel-mounting part
22
is formed to have a taper form, which works to reduce the clearance between the protrusion
12
and the groove bottom
229
, as the discharge vessel
10
is rotated in relation to the vessel-mounting part
22
. Optionally, the side wall of the groove
224
(i.e. height direction of the groove
224
) may further be formed to have a taper form, which facilitates the positioning of the discharge vessel in relation to the vessel-mounting part
22
, not only in the axis-direction, but also in a direction perpendicular to the axis-direction. This will further improve the mounting-position accuracy.
In addition, in the above embodiments, the groove bottom
229
has a taper form which continuously reduces its depth. However, the present invention is not confined to this structure, as long as the groove bottom
229
is formed to have a shorter distance between the center of the vessel-mounting part in the diameter direction along its outer edge. For example, a structure is also possible in which both of the side wall and the groove bottom
29
will continuously approach the center of the vessel-mounting part
22
in the diameter direction.
In addition, if the groove bottom
229
in the vessel-mounting part
2
is not formed to have a taper form in the first embodiment, it becomes necessary to achieve a size accuracy between an inner wall of the vessel-mounting part
22
and the protrusion of the discharge vessel
10
. Nevertheless, if the mentioned size accuracy is achieved in such a case, the same effect will be attained as stated in the above, compared to the conventional electrodeless discharge lamps.
In addition, in the above, the neck portion
11
of the discharge vessel
10
has, on its outer surface, four protrusions
12
. However, the number and form of the protrusion are not limited to as described. For example, an external screw thread (left-hand thread) will equally do. Furthermore, the neck portion
11
may have a groove, instead of protrusions
12
. In such a case, the same effect as that of the electrodeless fluorescent lamp
1
will be achieved, when the corresponding protrusion is provided for the vessel-mounting part, together with a cut-out portion so as to enable each protrusion of the vessel-mounting part to be freely inserted into the corresponding groove.
Still further, in the above description, the bobbin
20
includes the coil-holding part
21
and the vessel-mounting parts
22
or
23
that are formed as a single piece. However, these members may be formed independently first, then assembled together. In such a case, there will be more freedom at the production process. However, care is required, in assembling, so that the relative position between the parts will be kept accurate, and the parts after assembled should be coupled to each other tightly, without a chance of being separate, or rattling.
In addition, the protrusion
12
of the discharge vessel
10
is arranged to protrude outwardly in a diameter direction. However, the protrusion may be arranged to protrude inwardly in a diameter direction. In such a case, the vessel-mounting parts
22
and
23
are required to be formed to be able to receive the protrusion of the discharge vessel.
Still further, in the above, the ferrite core
35
is inserted into the bobbin
20
, and into the bobbin
26
. However, some electrodeless discharge lamps do not necessitate a ferrite core
35
, depending on the frequency of the signal supplied to the coil. Therefore, the present invention may have the same effect, even without the ferrite core.
Still further, the order of each process at the production is not limited to the above described embodiments. For example, a process of coupling the discharge vessel
10
to the bobbin
20
,
26
may be performed after the case
40
is fixed to the bobbin
20
,
26
.
Still further, in the second embodiment, injection of heat-resistance silicone is performed after a discharge vessel
10
has been coupled to the bobbin
26
. However, the silicone may be injected in the groove
234
of the bobbin
26
before the discharge vessel
10
is coupled to the bobbin
26
, so as to harden this silicone after the discharge vessel
10
has been inserted into the bobbin
26
and after the position of the discharge vessel
10
has been decided in relation to the bobbin
26
. In other words, the silicone may be injected, before the protrusion
12
of the discharge vessel
10
is inserted into the groove
234
of the bobbin
26
.
Although the present invention has been fully described by way of examples with references 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 construed as being included therein.
Claims
- 1. An electrodeless discharge lamp comprising:a translucent discharge vessel in which a discharge gas is enclosed, the discharge vessel having a first coupling member; an induction coil; and a bobbin that includes a coil-holding part and a vessel-mounting part that are formed as a single piece, the vessel-mounting part having a second coupling member, wherein the coil-holding part holds the induction coil on an outer surface thereof, and is placed in a proximity of the discharge vessel, and the first coupling member and the second coupling member are coupled so as to mount the discharge vessel on the vessel-mounting part of the bobbin.
- 2. The electrodeless discharge lamp of claim 1,wherein one of the first coupling member and the second coupling member is a protrusion, and the other is a groove that is shaped to receive the protrusion.
- 3. The electrodeless discharge lamp of claim 2,wherein the discharge vessel is coupled to the vessel-mounting part, so that the discharge vessel is held in a fixed position.
- 4. The electrodeless discharge lamp of claim 3,wherein the vessel-mounting part is a shallow dish and has a bottom, the second coupling member being the groove and being formed along an inner wall of the shallow dish.
- 5. The electrodeless discharge lamp of claim 4,wherein a portion is cut away from a wall portion that forms the groove, so as to enable the protrusion of the discharge vessel to be freely inserted into the groove.
- 6. The electrodeless discharge lamp of claim 5,wherein a distance between a groove bottom and a center of the vessel-mounting part continuously decreases in a diameter direction, the groove bottom being a part of an inner surface of the bottom that is under the groove, and the protrusion of the discharge vessel is guided toward a center of the vessel-mounting part in a diameter direction by being rotated along the groove bottom, so as to eventually hold the discharge vessel in a fixed position.
- 7. The electrodeless discharge lamp of claim 5,wherein the groove is formed along the inner wall so as to continuously decrease in height, and the protrusion of the discharge vessel is guided toward a height direction of the groove formed on the vessel-mounting part, by being rotated along the part of the inner wall, so as to eventually hold the discharge vessel in a fixed position.
- 8. The electrodeless discharge lamp of claim 6,wherein the discharge vessel is rotated leftward when the vessel-mounting part is seen from the discharge vessel.
- 9. The electrodeless discharge lamp of claim 2,wherein the discharge vessel is coupled to the vessel-mounting part, having a resin member between the protrusion and the groove.
- 10. The electrodeless discharge lamp of claim 1,wherein the vessel-mounting part fixes the bobbin to a case, the case including a connection part that electrically connects the bobbin to an external circuit.
- 11. The electrodeless discharge lamp of claim 10,wherein a driving circuit that drives the induction coil is provided in a space between the vessel-mounting part and the case.
- 12. The electrodeless discharge lamp of claim 1,wherein a light-reflective layer is formed on an area of the induction coil, the area opposing the discharge vessel.
- 13. The electrodeless discharge lamp of claim 1,wherein a phosphor layer is formed on an inner surface of the discharge vessel.
- 14. The electrodeless discharge lamp of claim 7,wherein the discharge vessel is rotated leftward when the vessel-mounting part is seen from the discharge vessel.
- 15. An electrodeless discharge lamp comprising:a translucent discharge vessel in which a discharge gas is enclosed, the discharge vessel having a first coupling member integrally formed as a set of a plurality of diametrically outwardly projecting protrusions; an induction coil; and a bobbin that includes a coil-holding part and a vessel-mounting part that are formed as a single piece, the vessel-mounting part having a second coupling member including a plurality of spaced overhanging walls, each wall of a configuration to engage a respective protrusion; wherein the coil-holding part holds the induction coil on an outer surface thereof, and is placed in a proximity of the discharge vessel, and the first coupling member and the second coupling member are coupled together so as to mount the discharge vessel on the vessel-mounting part of the bobbin.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2001-401790 |
Dec 2001 |
JP |
|
2002-038729 |
Feb 2002 |
JP |
|
US Referenced Citations (7)
Foreign Referenced Citations (5)
Number |
Date |
Country |
0 704 010 |
Sep 1999 |
EP |
62-262302 |
Nov 1987 |
JP |
08212981 |
Aug 1996 |
JP |
8-511650 |
Dec 1996 |
JP |
09320541 |
Dec 1997 |
JP |