Lamp with outer tube and attaching member

A lamp with an outer bulb is provided. The outer bulb is attached to an attaching member of a base by simple and convenient fabrication, and reliably prevents detachment of the outer bulb from the attaching member. An outer peripheral surface of a supporting post formed to the attaching member of the base and an inner peripheral surface of the outer bulb define a gap therebetween that may receive a heat resistant adhesive or filler. Convex portions facing the gap may be formed to the outer peripheral surface of the supporting post and the inner peripheral surface of the outer bulb, respectively, and a joint body for joining the outer bulb and the supporting post is defined between the outer peripheral surface of the supporting post and the inner peripheral surface of the outer bulb by the adhesive or filler in the gap.

FIELD OF THE INVENTION

The present invention concerns a lamp with an outer bulb in which an outer bulb for housing a lamp main body is attached with an aim, for example, of protecting the lamp main body against external damages, preventing scattering of flakes due to bursting and breakage of the lamp main body and suppressing and decreasing emission of UV-ray harmful to human bodies.

DESCRIPTION OF THE RELATED ART

The lamp of the type described above includes, for example, a metal vapor discharge lamp such as a metal halide lamp in which a lamp main body having a light emitting tube or a lamp main body having a light emitting tube and an airtight bulb containing the light emitting tube is housed in an outer bulb that constitutes an outer shell of the lamp, and a halogen lamp in which a lamp main body having a light emitting filament and an airtight bulb containing the light emitting tube is housed in an outer bulb that constitutes an outer shell of the lamp. Generally, in the lamp having the outer bulb described above, an attaching member to which the lamp main body and the outer bulb for housing the lamp main body are attached is formed to a base of the lamp and an outer bulb is secured to the attaching member by means of a heat resistant adhesive. However, when the adhesive strength of the adhesive is lowered due to aging deterioration of the adhesive, the outer bulb may possibly be detached and dropped from the attaching member of the base.

Then, for preventing the detachment of the outer bulb caused by the degradation of the heat resistant adhesive, a metal vapor discharge lamp such as a metal halide lamp of securing an outer bulb by means of a bayonet mechanism to the attaching member of a base was disclosed as shown inFIG. 5andFIG. 6(Referring to Patent Literature 1). The lamp inFIG. 5is a metal halide lamp in which a lamp main body51having a light emitting tube52made of ceramics containing a metal halide, mercury, and a starting gas sealed therein and an airtight bulb53made of quartz glass for containing the light emitting tube is housed in an outer bulb (protective tube)54made of hard glass having a strength capable of withstanding impact shocks upon explosion of the light emitting tube and capable of absorbing UV-rays at a low wavelength which are less absorbed by an airtight bulb made of quartz glass, and an attaching member56to which the lamp main body51and the outer bulb54for housing the lamp main body are attached is formed to a base55of the lamp.

In the attaching member56of the base55, as shown inFIGS. 6(a) and6(b), a circular cylindrical supporting post59for supporting and securing one end of the lamp main body51protrudes from a substrate (flange)58for closing an opening57of the outer bulb54and they are entirely formed integrally of steatite ceramics having a function as a porcelain insulator. Further, the supporting post59has a shape of a bisected circular cylinder by cutting a slit61for inserting a pinch seal60of the airtight bulb53that constitutes the lamp main body51from the top end thereof along the axial direction and securing the pinch seal60of the airtight bulb53by means of a heat resistant adhesive.

Two types of bayonet mechanism are disclosed for securing the outer bulb54to the attaching member56of the base55.

One is a type to engage a protrusion62as a bayonet finger protruded to the inner side of an opening57of the outer bulb54to a concave portion63as a bayonet groove formed to the peripheral surface of the supporting post59of the attaching member56as shown inFIG. 5andFIG. 6(a), and another is a type to engage a convex portion64as a bayonet finger protruded from the peripheral surface of the supporting post59of the attaching member56to an L-formed recess65as a bayonet groove formed by recessing the outer bulb54on the side of the opening into a hooked shape from the open end thereof as shown inFIG. 6(b).

Then, the outer bulb54is attached to the attaching member56of the base55by fabrication procedures of at first coating a heat resistant inorganic adhesive to the open end of the outer bulb54and the substrate (flange)58of the attaching member56of the base55against which the open end is to be abutted, bringing the open end of the outer bulb54into contact with the substrate (flange)58of the base55, twisting (rotating) the outer bulb54in this state, and engaging the convex portion62formed as the bayonet finger to the outer bulb54and the concave portion63formed as the bayonet groove to the supporting post59of the attaching member56of the base55to each other in the type shown inFIG. 6(a), or engaging the convex portion64as the bayonet finger formed to the supporting post59of the attaching member56of the base55and the L-formed recess65as the bayonet groove formed to the outer bulb54to each other in the type shown inFIG. 6(b), thereby securing the outer bulb54by means of the bayonet mechanism to the attaching member56of the base55, then baking the heat resistant inorganic adhesive coated as described above to connect the open end of the outer bulb54with the substrate (flange)58of the base55for preventing detachment of the outer bulb54from the attaching member56of the base55by the rotation of the outer bulb54in the direction of disengaging the engaged state between the bayonet finger and the bayonet groove caused by vibrations, etc.[Patent Literature 1] WO2007/088729

However, since the fabrication procedure of attaching the outer bulb54to the attaching member56of the base55by the double anti-falling off structure by means of the bayonet mechanism and the heat resistant adhesive is complicate in view of the fabrication step and takes much time, this may possibly lower the productivity of the lamps remarkably.

Further, in the anti-falling off structure by the bayonet mechanism, since the bayonet finger has to be engaged by screwing it into the bayonet groove, this may possibly damage the convex portion62as the bayonet finger formed to the outer bulb54ofFIG. 6(a), or damage the L-formed recess65as the bayonet groove formed to the outer bulb54ofFIG. 6(b) by inadequate control for the force that exerts upon screwing operation.

Further, since the convex portion62formed to the outer bulb54and the concave portion63formed to the supporting post59of the attaching member56of the base55inFIG. 6(a) have to be fabricated each into such a shape and a size as capable of engagement to each other so as to constitute the bayonet finger and the bayonet groove of the bayonet mechanism, or the L-formed recess65formed to the outer bulb54and the convex portion64formed to the supporting post59of the attaching member56of the base55inFIG. 6(b) have also to be fabricated each into a shape and a size as capable of engagement to each other so as to constitute the bayonet groove and the bayonet finger of the bayonet mechanism, this involves a problem of making the fabrication of them troublesome and increasing the fabrication cost, as well as a problem of causing a disadvantage of making the engagement between the bayonet finger and the bayonet groove difficult or impossible when the fabrication accuracy is poor, thereby lowering the production yield of lamps.

Further, in the anti-falling off structure by means of the heat resistant adhesive, the open end of the outer bulb54is bonded to the substrate (flange)58of the attaching member56of the base55by means of the heat resistant adhesive for preventing falling off of the outer bulb54from the attaching member56of the base55which is caused by rotation of the outer bulb54in the direction of disengaging the engaged state of the bayonet mechanism by vibrations, etc. However, when the adhesive loses the adhesive strength by aging deterioration, the outer bulb54may possibly rotate in the direction of disengaging the engaged state of the bayonet mechanism, thereby detaching the outer bulb54from the attaching member56of the base55.

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The present invention intends to attain a technical subject capable of attaching an outer bulb to an attaching member of a base not by means of the adhesive strength of the adhesive and, at the same time, capable of reliably preventing the detachment of the outer bulb by simple and convenient fabrication with no worry of damaging the outer bulb and without requiring strict fabrication accuracy.

Means for Solving the Problems

In accordance with the present invention, the technical subject described above is attained by a lamp with an outer bulb, in which

an attaching member for attaching a lamp main body and an outer bulb for housing the lamp main body is formed to a base and a supporting post for supporting and securing the lamp main body is formed to a substrate for closing the opening of the outer bulb, wherein

the outer peripheral surface of the supporting post and the inner peripheral surface of the outer bulb opposed to the outer peripheral surface define therebetween a gap for filling a heat resistant adhesive or filler, a concave portion or a convex portion facing the gap is formed to each of the outer peripheral surface of the supporting post and the inner peripheral surface of the outer bulb, and a joint body for joining the outer bulb and the supporting post is cast in mold being defined with the supporting post and the outer bulb by means of the adhesive or filler filled in the gap.

Advantageous Effect of the Invention

According to the invention, the outer bulb can be attached to the attaching member of the base and, at the same time, detachment of the outer bulb from the attaching member can be prevented by simple and convenient fabrication of merely forming a convex portion or a concave portion to each of the outer peripheral surface of the supporting post formed to the attaching member of the base and the inner peripheral surface of the outer bulb opposite thereto respectively, and filling the heat resistant adhesive or filler to the gap defined between the outer peripheral surface of the supporting post and the inner peripheral surface of the outer bulb.

Further, since the outer bulb is attached to the attaching member of the base not by means of the adhesive strength of the adhesive or the filler but by means of the joint body molded from the adhesive or the filler, even when the adhesive strength of the adhesive or filler is lost by aging deterioration, there is no possibility that the outer bulb should detach from the attaching substrate of the base.

Further, since detachment of the outer bulb is not prevented by the direct engagement of the convex portion or the concave portion formed to the outer peripheral surface of the supporting post and that formed to the inner peripheral surface of the outer bulb to each other, fabrication of forming the convex portion or the concave portion requires no strict accuracy. Further, when the outer bulb is attached to the attaching member of the base, there is no possibility that the convex portion or the concave portion formed to the outer bulb is broken.

PREFERRED EMBODIMENTS OF THE INVENTION

In preferred embodiments of a lamp with an outer bulb according to the present invention, a base has an attaching member to which are attached a lamp main body and an outer bulb housing the lamp main body, and the attaching member of the base has a supporting post formed to a substrate (flange) for closing an opening of the outer bulb for supporting and securing the lamp main body, and they are entirely formed of a porcelain material such as ceramics. The lamp main body includes, for example, a light emitting tube, a light emitting tube and an airtight bulb containing the light emitting tube, or a light emitting filament and an airtight bulb containing the light emitting filament, and the outer bulb for housing the lamp main body is formed of hard glass or quartz glass.

Then, the outer peripheral surface of the supporting post formed to the attaching member of the base and the inner peripheral surface of the outer bulb opposed to the outer peripheral surface of the supporting post define a gap therebetween for filling a heat resistant adhesive or filler, a concave portion or a convex portion facing the gap is formed to each of the outer peripheral surface of the supporting post and the inner peripheral surface of the outer bulb respectively. A joint body for joining the outer bulb and the supporting post is cast in mold defined with the supporting post and the outer bulb by means of a low temperature curable pasty inorganic heat resistant adhesive or filler filled in the gap.

The concave portion or the convex portion formed to the outer peripheral surface of the supporting post is formed as a substantially semi-spherical concave or convex portion, or as a concave groove or a convex ridge extending in the circumferential direction of the supporting post, the concave portion or the convex portion formed to the inner peripheral surface of the outer bulb is formed as a substantially semi-spherical concave or convex portion or as a concave groove or a convex ridge extending in the circumferential direction of the outer bulb. Each of the substantially semi-spherical concave portion or convex portion formed to the supporting post and the outer bulb is preferably formed in plurality each spaced at a pitch in the circumferential direction of the supporting post or the outer bulb. Further, each of the concave groove or the convex ridge formed to the supporting post and the outer bulb is preferably formed in plurality intermittently along the circumferential direction of the supporting post or the outer bulb, or formed as a continuous annular concave groove or convex ridge along the circumferential direction of the supporting post or the outer bulb.

FIGS. 1A to 1Care views showing an embodiment of a lamp with an outer bulb according to the invention andFIGS. 2(a) to2(c) are views showing modified examples for a main portion thereof. The lamp of this embodiment is a metal halide lamp, as shown in the entire view ofFIG. 1(c), in which a lamp main body1has a light emitting tube2made of ceramics and an airtight bulb3made of quartz glass for containing the light emitting tube2, and a base4has an attaching member6for attaching the lamp main body1, and an outer bulb5made of hard glass or quartz glass for housing the lamp main body1.

In the attaching member6of the base4, a supporting post9for supporting and securing the lamp main body1is formed to a substrate (flange)8for closing an opening7of the outer bulb5and they are entirely formed of a porcelain material such as ceramics. A slit11is cut in the supporting post9from the top end thereof along the axial direction for inserting a pinch seal10of the airtight bulb3that constitutes the lamp main body1and securing the pinch seal10by means of a heat resistant adhesive.

Then, as shown inFIG. 1(a), a gap12is defined between the outer peripheral surface of the supporting post9and the inner peripheral surface of the outer bulb5opposite thereto for filling a heat resistant adhesive or filler, and a convex portion13and a convex portion14facing the gap12are formed to the outer peripheral surface of the supporting post9and the inner peripheral surface of the outer bulb5opposed to each other respectively. In the gap12, a joint body J for joining the outer bulb5, and the supporting post9is cast in mold defined with the supporting post9and the outer bulb5by means of a heat resistant adhesive or filler S filled as shown inFIG. 1(c). The convex portion13of the supporting post9is formed as a substantially semi-spherical convex portion or a convex ridge extending in the circumferential direction of the supporting post9, and the convex portion14of the outer bulb5is formed as a substantially semi-spherical convex portion or a convex ridge extending in the circumferential direction of the outer bulb5.

The heat resistant adhesive or filler S comprises a low temperature curable pasty inorganic adhesive or filler such as SUMICERAM (trade name of products, manufactured by Asahi Chemical Co., Ltd.) capable of curing at a low temperature, for example, of about 100 to 300° C. and capable of withstanding a high temperature of 1000 to 2000° C. When the paste-like adhesive or filler S is cast to the outer peripheral surface of the supporting post9and the inner peripheral surface of the outer bulb5divisionally each by an amount necessary for filling the gap12and the outer bulb5is capped over the lamp main body1and the supporting post9in the direction as shown by an arrow in the drawing as shown inFIG. 1(b), the pasty adhesive or filler S, S cast to the outer peripheral surface of the supporting post9and the inner peripheral surface of the outer bulb5divisionally are adhered and integrated to each other into a state in which the adhesive or filler S is cast in the gap12defined between the outer peripheral surface of the supporting post9and the inner peripheral surface of the outer bulb5as shown inFIG. 1(c).

When the adhesive or filler S is thermally cured at a low temperature in this state, the adhesive or filler S forms a joint body J for joining the outer bulb5and the supporting post9, and the joint body J attaches the outer bulb5to the attaching member6of the base4and, at the same time, inhibits detachment of the outer bulb5from the attaching member6.

As described above, since the outer bulb5is not bonded to the supporting post9by the adhesive strength of the adhesive or filler S but it is joined to the supporting post9by means of the joint body J which is cast in mold by means of the adhesive or filler S, even when the adhesive strength of the adhesive or filler S is lost by aging deterioration, there is no possibility that the outer bulb5is detached from the attaching member6of the base4. Further, even when the adhesive or filler S retains no substantial adhesion effect at all, detachment of the outer bulb5can be inhibited reliably to improve the quality of products and the reliability of the lamp remarkably.

Further, since the outer bulb5is not attached to the attaching member6of the base4by direct engagement of the convex portion14formed to the inner peripheral surface thereof to the outer peripheral surface of the supporting post9, there is no possibility that the convex portion14of the outer bulb5is damaged upon attachment to the attaching member6.

Further, since it may suffice that the convex portion14of the outer bulb5and the convex portion13of the supporting post9have such a size as capable of casting the joint body J in mold for joining the outer bulb5and the supporting post9and no strict dimensional accuracy is necessary, fabrication of shaping the convex portion14and the convex portion13is relatively easy and fabrication failure less occurs. Further, since the joint body J for joining the outer bulb5and the supporting post9is cast in mold and the outer bulb5is attached to the attaching member6of the base4, as well as detachment of the outer bulb5from the attaching member6is inhibited reliably by simple and convenient fabrication of merely filling the adhesive or filler S between the inner peripheral surface of the outer bulb5and the outer peripheral surface of the supporting post9formed with the convex portion14and the convex portion13, and curing the adhesive or filler S, the fabrication cost for attaching the outer bulb5is not increased and there is no worry that the productivity of the lamp is lowered.

In the lamp shown inFIG. 1, while the convex portions13,14are formed to both of the supporting post9and the outer bulb5, this may be modified, for example, by shaping a concave portion15to the outer peripheral surface of the supporting post9and shaping a convex portion16to the inner peripheral surface of the outer bulb5as shown inFIG. 2(a), by shaping a convex portion17to the outer peripheral surface of the supporting post9and shaping a concave portion18to the inner peripheral surface of the outer bulb5as shown inFIG. 2(b), or by forming concave portions19,20both to the outer peripheral surface of the supporting post9and the inner peripheral surface of the outer bulb5as shown inFIG. 2(c). Further, the convex portion16of the outer bulb5shown inFIG. 2(a) may be a substantially semi-spherical convex portion, or a convex ridge extending in the circumferential direction of the outer bulb5formed by thermally softening a portion of the outer bulb5, each of the concave portions18and20of the outer bulb5shown inFIG. 2(b) andFIG. 2(c) may be a semi-spherical concave portion or a concave groove extending in the circumferential direction of the outer bulb5formed by thermally softening a portion of the outer bulb5, and the concave portion19of the supporting post9shown inFIG. 2(c) may be a semi-spherical concave portion, or a concave groove extending in the circumferential direction of the supporting post9.

FIG. 3is an entire view showing another embodiment of a lamp with an outer bulb according to the invention,FIG. 4(a) is a view showing the structure for a main portion of the lamp andFIG. 4(b) is a structure of a joint body cast in mold by means of a heat resistant adhesive or filler. The lamp inFIG. 3is a halogen lamp in which a lamp main body31has a light emitting filament32and an airtight bulb33made of quartz glass for containing the filament. An attaching member36is formed to a base34for attaching the lamp main body31and an outer bulb35made of hard glass for housing the lamp main body31.

In the attaching member36of the base34, a circular cylindrical supporting post39for supporting and securing the lamp main body31is formed at the central region of a substrate (flange)38for closing the opening of the outer bulb35, an annular peripheral wall40is formed along the outer periphery of the substrate (flange)38for inwardly fitting the open end of the outer bulb35, and the attaching member36is entirely formed of a porcelain material such as ceramics. Further, a slit42is cut in the supporting post39from the top end along the axial direction thereof for inserting a pinch seal41of the airtight bulb33that constitutes the lamp main body31and securing the pinch seal41by means of a heat resistant adhesive.

Then, as shown inFIG. 4(a), a gap43is defined between the outer peripheral surface of the supporting post39and the inner peripheral surface of the outer bulb35opposed to the outer peripheral surface of the supporting post for filling a heat resistant adhesive or filler, a convex portion44and a convex portion45facing the gap43are formed respectively to the outer peripheral surface of the supporting post39and the inner peripheral surface of the outer bulb35opposed to each other. Then, a joint body J2for joining the outer bulb35and the supporting post39is cast in mold within the gap43as shown inFIG. 4(b) by means of the heat resistant adhesive or filler S filled as shown inFIG. 3.

The convex portion44of the supporting post39is formed as a convex ridge extending in the circumferential direction of the supporting post39. Further, the convex portion45of the outer bulb35is formed by the fabrication of tapering, that is, diametrically decreasing the open end of the outer bulb35for fitting the open end of the outer bulb35toward the inside of the circumferential wall40of the substrate (flange)38formed to the attaching member36of the base34, and this forms an annular convex portion protruding toward the inside of the outer bulb35.

Then, a concave portion46comprising a concave groove for engagement with the convex portion44formed to the outer peripheral surface of the supporting post39and an annular step47for engagement with the annular convex portion45formed to the inner peripheral surface of the outer bulb35are formed to the joint body J2cast in mold by means of the adhesive or filler S filled in the gap43defined between the outer peripheral surface of the supporting post39formed to the attaching member36of the base34and the inner peripheral surface of the outer bulb35opposed to the outer peripheral surface of the supporting post39.

Thus, the joint body J2can attach the outer bulb35to the attaching member36of the base34and, at the same time, can inhibit detachment of the outer bulb35from the attaching member36of the base34. Further, the joint body J2can reliably prevent detachment of the outer bulb35even when the heat resistant adhesive forming the joint body loses the adhesion effect thereof due to aging deterioration, or even when it is formed of a heat resistant filler not having an adhesive function.

While each of the outer bulbs5and35of the embodiments has a cylindrical shape, the outer bulb of the invention is not restricted to the cylindrical outer bulb. Further, the outer bulb of the invention also includes those referred to as an outer sphere, an outer spherical bulb, and an outer bulb.

INDUSTRIAL APPLICABILITY

The present invention can simplify the fabrication of attaching the outer bulb of the lamp with the outer bulb to the attaching member of the base and, at the same time, can reliably prevent detachment of the outer bulb attached to the attaching member of the base, thereby contributing to the improvement of the quality and the reliability of the lamp with the outer bulb.

DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIGS. 1(a)-(c) show an embodiment of a lamp with an outer bulb according to the invention;

FIGS. 2(a)-(c) show modified examples for a main portion of the lamp shown inFIG. 1;

FIG. 3is a view showing another embodiment of a lamp with an outer bulb according to the invention;

FIGS. 4(a)-(b) show the constitution for a main portion of the lamp shown inFIG. 3and structure of a joint body thereof;

FIG. 5is a view showing an existent lamp with an outer bulb;

FIGS. 6(a)-(b) are fragmentary views showing examples for a main portion of an existent lamp with an outer bulb.

DESCRIPTION OF THE REFERENCES