Vehicle light bulb

Abstract: To further prolong the life of vehicle light bulbs by improving the way in which the legs of the dipped beam filament are fixed. The invention is characterized in that dipped beam filament 6 is attached by forming a hole 5a in cupped shield 5, fixing one leg 6a directly to common lead 4 by passing this leg 6a through the hole, and fixing the other leg 6b directly to lead 7. Even supposing shield 5 vibrates as shown by arrows 2 ○ and 2 ○, this vibration is not transmitted to dipped beam filament 6. Accordingly, the life of dipped beam filament 6 can be further prolonged.

Description: The present invention relates to a vibration-resistant vehicle light bulb applied to automobiles and other types of vehicle wherein a common lead, a dipped beam filament, a lead for the use thereof, a main beam filament and a lead for the use thereof are accommodated inside a glass bulb and a shield is fixed to said common lead along the dipped beam filament. Figure 18 shows a side view of a conventional automobile light bulb called an "H4", wherein the automobile light bulb 100 comprises a glass bulb 101, a cap 102 that seals off the opening of glass bulb 101, a common lead 103, a cupped shield 104 secured by welding to the top of this common lead 103, a dipped beam filament 105 disposed along this shield 104, a lead 106 for the use thereof, a main beam filament 107 disposed below shield 104, a lead 108 for the use thereof, and a reinforcing bridge 109, a halogen gas being sealed inside glass bulb 101. One leg 105a of dipped beam filament 105 is affixed to shield 104, and the other leg 105b is affixed to lead 106. The three leads 103, 106 and 108 project from cap 102 in the form of cantilever beams, so that these leads 103, 106 and 108 vibrate more toward the tip (the top end) when they are subjected to vibration. Shield 104, which is even further away from cap 102, has a large vibration amplitude, and unless shield 104 is securely welded to common lead 103, the vibration of shield 104 will be dalayed with respect to that of common lead 103 so that - when the vibration amplitude increases, the stress in dipped beam filament 105 disposed along it will increase and its life will become shortened as a result. Unexamined Published Japanese Utility Model Application (JP-A-U) No. S64-2356 (1989) was therefore proposed to combat this problem. The proposed light bulb is described in the following. Figure 19 shows a side view of a conventional vibration-resistant automobile light bulb, wherein the automobile light bulb 110 comprises a glass bulb 111, a cap 112 that seals off the opening of glass bulb 111, a common lead 113 whose tip reaches the neck part 111a of glass bulb 111, a cupped shield 114 that is secured by welding to the mid-part of this common lead 113, a dipped beam filament 115 disposed along this shield 114, a lead 116 for the use thereof, a main beam filament 117 disposed below shield 114, a lead 118 for the use thereof, and a reinforcing bridge 119, a halogen gas being sealed inside glass bulb 111. One leg 115a of dipped beam filament 115 is affixed to shield 114, and the other leg 115b is affixed to lead 116. Since common lead 113 is a beam supported at both ends when its tip is fixed to neck part 111a, its flexion is markedly less than that of a cantilever beam, and its vibration amplitude is also small. The life of dipped beam filament 115 is thus greatly prolonged. Thus light bulb 110, which comprises lead 113 linked to glass bulb 111, is called a vibration-resistant automobile light bulb. Figure 20 shows a cross section along line 20-20 in Figure 19, wherein supped shield 114 is affixed by projection welding to common lead 113. More specifically, a small projection is formed from metal shield 114 to the right of the figure, this projection is brought into contact with common lead 113, and an electrical current is made to flow, causing the electrical current to concentrate at the projection which is welded by the resulting Joule heat. Figure 21 is a view along arrow 21 in Figure 19, showing how one leg 115a of dipped beam filament 115 is fixed to cupped shield 114 and the other leg 115b is fixed to lead 116. As this figure shows, dipped beam filament 115 is formed from a coil spring of heating wire, pulled out by a distance L in a tangential direction at the end part 115c of the coil, and is then bent up to make a conventional leg structure. In Figure 20, there is a danger that shield 114 will vibrate as shown by arrows 1 ○, 1 ○ centered on the welding point 121. If this happens, it would be inconvenient because dipped beam filament 115 - which is attached at one end to lead 116 and at the other end to shield 114 - will also vibrate. Also, in Figure 21, because leg 115a is separated by a distance L from the center of glass bulb 111, it is also inconvenient in that leg 115a vibrates along with the vibration of shield 114. EP-A-0776025, which is prior art according to Art. 54(3) EPC, discloses a vehicle light bulb comprising a glass bulb having a light-shielding film applied to the tip of said glass bulb, a dipped beam filament having one leg fixed directly to a common lead and the other to a first lead, a main beam filament having one leg fixed directly to the common lead and the other to a second lead, and a shield fixed to said common lead along the dipped beam filament and having a hole in which said one leg of the dipped beam filament is guided to said common lead by passing it through this hole. EP-A-0 791 779, which is also prior art according to Art. 54(3) EPC, discloses a vehicle light bulb wherein a common lead, a dipped beam filament, a lead for the use thereof, a main beam filament and a lead for the use thereof are accommodated inside a glass bulb and a shield is fixed to said common lead along the dipped beam filament. Said shield comprises a cup part and a tongue part that is fixed extending from said cup so as to pass through roughly the center of the bulb, and the tongue part is fixed to said one leg of the dipped beam filament at roughtly the central position of the glass bulb. It is not disclosed where the one leg is fixed at the tongue part in the width direction thereof. It is therefore an objective of the present invention to prolong the life of light bulbs applied to vehicles such as automobiles by improving the method for fixing the legs of the dipped beam filament. According to a first aspect, the invention of claim 1 is characterized in that said shield comprises a cup part and a tongue part that is fixed extending from said cup so as to pass through roughly the center of the bulb, and in that one leg of the dipped beam filament is fixed to the center of the tongue part in the width direction of the tongue part at roughly the central position of the glass bulb. When the shield vibrates, since one leg of the dipped beam filament is fixed at the center of swaying, the vibration amplitude of the dipped beam filament can be suppressed and the life of the vehicle light bulb can be further prolonged. According to a second aspect, the invention of claim 2 is characterized in that the dipped beam filament consists of a coil part comprising a conductor formed in the shape of a coil spring, one leg that extends out in a straight line from one end of the coil part along a line that is tangential to the coils of this coil part, and another leg that extends out in a straight line from the other end of the coil part along a line that is tangential to the coils of this coil part and is perpendicular to this one leg, and in that the one leg is fixed to the shield and the other leg is fixed to the dipped beam filament lead. Even if the one leg vibrates due to vibration of the shield, this vibration can be absorbed by the coil part so that the life of the vehicle light bulb can be further prolonged. It is preferred that the shield is provided with a tongue part for fixing the other leg. Since the tongue part is provided, it is easy to fix the other leg of the dipped beam filament to the shield. According to a third aspect, the invention of claim 4 is characterized in that the dipped beam filament consists of a coil part comprising a conductor formed in the shape of a coil spring, one leg that extends out in a straight line from one end of the coil part along a line that is tangential to the coils of this coil part, and another leg that extends out in a straight line from the other end of the coil part along a line that is tangential to the coils of this coil part and is perpendicular to this one leg, and in that the one leg is fixed to the common lead and the other leg is fixed to the dipped beam filament lead. Even if the one leg vibrates due to vibration of the common lead, this vibration can be absorbed by the coil part and the life of the vehicle light bulb can be further prolonged. Embodiments of the present invention are described below based on the accompanying figures. Figure 1 is a side view of an automobile light bulb (first embodiment as comparative example, not part of the present invention) Figure 2 is a cross section along line 2-2 in Figure 1. Figure 3 is a side view of an automobile light bulb (second embodiment as comparative example, not part of the present invention) Figure 4 is an oblique view of the salient parts of an automobile light bulb (second embodiment) Figure 5 is a figure for explaining the operation of an automobile light bulb (second embodiment) Figure 6 is a side view of the salient parts of an automobile light bulb (third embodiment) relating to the present invention. Figure 7 is a view along arrow 7 in Figure 6. Figure 8 is a side view of an automobile light bulb (fourth embodiment) according to the present invention. Figure 9 is an oblique view showing the salient parts of an automobile light bulb (fourth embodiment) relating to the present invention. Figure 10 is a view along arrow 10 in Figure 9. Figure 11 are figures for explaining the operation of an automobile light bulb (fourth embodiment) according to the present invention. Figure 12 is a side view of the salient parts of an automobile light bulb (fifth embodiment) according to the present invention. Figure 13 is a figure for explaining the operation of an automobile light bulb (fifth embodiment) according to the present invention. Figure 14 is an oblique view showing the salient parts of an automobile light bulb (sixth embodiment) relating to the present invention. Figure 15 is a view along arrow 15 in Figure 14. Figure 16 is an oblique view showing the salient parts of an automobile light bulb (seventh embodiment) according to the present invention. Figure 17 are figures for explaining the operation of an automobile light bulb (seventh embodiment) relating to the present invention. Figure 18 is a side view of a conventional automobile light bulb. Figure 19 is a side view of a conventional vibration-resistant automobile light bulb. Figure 20 is a cross section along line 20-20 in Figure 19. Figure 21 is a view along arrow 21 in Figure 19. Figure 1 shows a side view of an automobile light bulb (first embodiment) not part of the present invention, where automobile light bulb 1 is a vehicle light bulb comprising a glass bulb 2, a cap 3 that seals off the opening of glass bulb 2, a common lead 4 whose tip reaches the neck part 2a of glass bulb 2, a cupped shield 5 secured by welding midway along this common lead 4, a dipped beam filament 6 disposed along this shield 5, a lead 7 for the use thereof, a main beam filament 8 disposed below shield 5, a lead 9 for the use thereof, and a reinforcing bridge 11, a halogen gas being sealed inside glass bulb 2. One leg 6a of dipped beam filament 6 is affixed to lead 7, and the other leg 6b is affixed to shield 5. Note that when main beam filament 8 is selected, main beam filament 8 is lit by the following circuit: lead 9 → main beam filament 8 → common lead 4 → (or the reverse thereof). Also, when dipped beam filament 6 is selected, dipped beam filament 6 is lit by the following circuit: lead 7 → dipped beam filament 6 → common lead 4 (or the reverse thereof). Figure 2 shows a cross section along line 2-2 in Figure 1, illustrating how dipped beam filament 6 is attached. That is, it is characterized in that dipped beam filament 6 is attached by forming a hole 5a in cupped shield 5, fixing one leg 6a directly to common lead 4 by passing this leg 6a through the hole, and fixing the other leg 6b directly to lead 7. Even supposing shield 5 vibrates as showns by arrows 2 ○ and 2 ○, this vibration is not transmitted to dipped beam filament 6. Accordingly, the life of dipped beam filament 6 can be further prolonged. Figure 3 shows a side view of an automobile light bulb (second embodiment) not part of the present invention, where, as in embodiment 1, automobile light bulb 1B comprises a glass bulb 2, a cap 3, a common lead 4, a dipped beam filament 6, a lead 7 for the use thereof, a main beam filament 8, a lead 9 for the use thereof and a reinforcing bridge 11, along with a shield 15 and light-shielding film 16 that are peculiar to this embodiment. Light-shielding film 16 has also been employed in conventional automobile light bulbs, but the shape of shield 15 is a characterizing feature. Figure 4 shows an oblique view of the salient parts of an automobile light bulb (second embodiment) not part of the present invention, which is characterized in that shield 15 has a half-cup shape with the top part cut away, and in that one leg 6a of dipped beam filament 6 reaches common lead 4 through this cutaway portion. Since one leg 6a of dipped beam filament 6 is fixed directly to common lead 4 after passing over the top of shield 15 while the other leg 6b is fixed directly to lead 7, even supposing shield 15 vibrates, its effects do not extend to dipped beam filament 6. Accordingly, the life of dipped beam filament 6 can be further prolonged. Figure 5 is a figure for explaining the operation of an automobile light bulb (second embodiment) not part of the present invention, which is a theoretical view for confirming the operation of shield 15 whose top part (to the left of the figure) has been cut away. Since the light emitted directly from dipped beam filament 6 is shielded by shield 15, the light projects to the top and to the right of the figure, with very little of it reaching toward the bottom of the figure. The light that reaches the right of the figure directly (at angle ) proceeds no further because it is shielded by light-shielding film 16. On the other hand, the direct light projected upward is reflected by parabolic mirror 17 and then proceeds as shown by arrows 3 ○ and 4 ○. Thus, despie the fact that shield 15 is a half cup with its top part cut away, its operation is in no way inferior to that of a full-cup shield (e.g. item 104 in Figure 18). Figure 6 shows a side view of the salient parts of an automobile light bulb (third embodiment) relating to the present invention; this figure is more or less the same as the side view of a conventional automobile light bulb, and shows the relative positions of glass bulb 2, common lead 4, shield 25, dipped beam filament 26, and lead 7 for the use thereof. As the figure shows, shield 25 comprises a cup part 27, a tongue part 28 that bulges out from the top edge, and a protruding strip 29 formed midway along tongue part 28, and tongue part 28 is positioned more or less in the center of glass bulb 2. Figure 7 shows a view along arrow 7 in Figure 6, wherein protruding strip 29 formed on tongue part 28 is the part that is joined to one leg 26a of dipped beam filament 26. The important point here is that one leg 26a of dipped beam filament 26 is affixed to the center of tongue part 28 in the width direction, that is, more or less at the central position of glass bulb 2. Additionally, the upper coiled end part of dipped beam filament 26, which has a coil spring shape, is formed into a " " or "C" shape when viewed horizontally, and leg 26a is pulled out to above the center of winding. As a result, leg 26a can be fixed to the center of tongue part 28 in the width direction. Since one leg 26a of dipped beam filament 26 is fixed to the vibrational center when shield 25 vibrates, the vibration of dipped beam filament 26 can be suppressed, and the life of the automobile light bulb can be further prolonged. Figure 8 shows a side view of an automobile light bulb (fourth embodiment) according to the present invention where, as in embodiment 1, automobile light bulb 1C comprises a glass bulb 2, a cap 3, a lead 7 for the dipped beam filament, a main beam filament 8, a lead 9 for the use thereof, a reinforcing bridge 11, and a common lead 35, along with a shield 36 and dipped beam filament 37 that are peculiar to this embodiment. Like the common lead 103 used in the ordinary light bulb of Figure 18, common lead 35 is a cantilever beam whose tip is separated from neck part 2a of glass bulb 2. Note that shield 36 and dipped beam filament 37 are described in Figure 9. Figure 9 is an oblique view showing the salient parts of an automobile light bulb (fourth embodiment) relating to the present invention, where dipped beam filament 37 comprises a coil part 40 made by forming a wire-shaped conductor 38 into a coil spring, one leg 41 extending out in a straight line from one coiled end part 40a of this coil part 40, and another leg 42 extending out in a straight line from the other coiled end part 40b of coil part 40 at right angles to this one leg 41, and is characterized in that the tip 41 a of the one leg 41 is fixed to tongue part 36a of shield 36, and the tip 42a of the other leg 42 is fixed to the lead 7 for the dipped beam filament. Figure 10 is a view along arrow 10 in Figure 9, showing a plan view of coil part 40. Since coil part 40 appears circular in plan view, the circle traced by the center of wire-shaped conductor 38 is referred to as coil circle 43. One leg 41 is a member that extends out in a straight line from one coiled end part 40a of coil part 40 at a tangent to coil circle 43, and the other leg 42 is a member that extends out in a straight line from the other coiled end part 40b of coil part 40 at a tangent to coil circle 43 and at right angles to one leg 41. One leg 41 and the other leg 42 are mutually perpendicular. This is because when vibration occurs in one leg 41 and/or the other leg 42, the vibration is absorbed by causing twisting in coil part 40. Figures 11(a) through (e) are figures for explaining the operation of an automobile light bulb (fourth embodiment) according to the present invention, which is a theoretical view for confirming the operation of dipped beam filament 37. Figure 11(a) shows the vibration directions X1, X2, Y1 and Y2 of shield 36. When automobile light bulb 1C vibrates, lead 7 for the dipped beam filament also vibrates along with shield 36, but since the vibration amplitude of lead 7 is small compared with that of shield 36, only the vibration of shield 36 will be described. Figure 11(b) shows how, when shield 36 vibrates in direction X1, one leg 41 vibrates with amplitude ΔX in direction X1. As a result, the vibration is absorbed by the side of one coiled end 40a of coil part 40 twisting in the direction of arrow N1. Figure 11(c) shows how, when shield 36 vibrates in direction X2, one leg 41 vibrates with amplitude ΔX in direction X2. As a result, the vibration is absorbed by the side of one coiled end 40a of coil part 40 twisting in the direction of arrow N2. Figure 11(d) shows how, when shield 36 vibrates in direction Y1, one leg 41 vibrates with amplitude ΔY in direction Y1. As a result, the vibration is absorbed by the side of one coiled end 40a of coil part 40 twisting in the direction of arrow N1. Figure 11(e) shows how, when shield 36 vibrates in direction Y2, one leg 41 vibrates with amplitude ΔY in direction Y2. As a result, the vibration is absorbed by the side of one coiled end 40a of coil part 40 twisting in the direction of arrow N2. Figure 12 is a side view of the salient parts of an automobile light bulb (fifth embodiment) according to the present invention, showing the relative positions of glass bulb 2, common lead 35, shield 45, dipped beam filament 37, lead 7 for the use thereof, and light-shielding film 16. As in the fourth embodiment, dipped beam filament 37 has the tip 41 a of one leg 41 fixed to the tongue part 45a of shield 45, and has the tip 42a of the other leg 42 fixed to the lead 7 for the dipped beam filament. Shield 45 is a member having a half-cup shape like shield 36 of the fourth embodiment but with the top part cut away, the tip of the cutaway part 45b being extended up to a straight line 46 joining dipped beam filament 37 to the tip part 16a of light-shielding film 16. This is because direct rays of light emitted from dipped beam filament 37 are shielded by shield 45. Since shield 45 can be made lighter, the vibration of shield 45 can be made smaller. Accordingly, the life of dipped beam filament 37 can be further prolonged. Figure 13 is a figure for explaining the operation of an automobile light bulb (fifth embodiment) according to the present invention, which is a theoretical view for confirming the operation of shield 45 whose top part (to the right of the figure) has been cut away. Rays of light emitted directly from dipped beam filament 37 are blocked by shield 45 to prevent them from reaching down to the bottom of the figure, but proceed to the top of the figure where they are reflected by parabolic mirror 17 and then proceed in the direction of the arrows. Accordingly, the operation of shield 45 is in no way inferior to that of the full-cup shield 36 described in, for example, the fourth embodiment, even though it is a half-cup with the top part cut away. Figure 14 is an oblique view showing the salient parts of an automobile light bulb (sixth embodiment) relating to the present invention. The sixth embodiment is characterized in that the tip 41 a of one leg 41 of dipped beam filament 37 is fixed to common lead 35, and in that the tip 42a of the other leg 42 is fixed to lead 47 for the dipped beam filament. Shield 15 is a half-cup with the top part cut away, which is identical to the member in the second embodiment. Lead 47 for the dipped beam filament is a member whose tip part is curved along the left side of shield 15. Figure 15 is a view along arrow 15 in Figure 14, showing how the tip 41 a of one leg 41 is fixed to common lead 35 and the tip 42a of the other leg 42 is fixed to lead 47 for the dipped beam filament. Since the one leg 41 and the other leg 42 of dipped beam filament 37 are also arranged at right angles in this embodiment, it is possible to absorb vibration with coil part 40 in the same way as in the fourth embodiment. Figure 16 is an oblique view showing the salient parts of an automobile light bulb (seventh embodiment) according to the present invention, this embodiment being characterized in that common lead 50 is a beam supported at both ends by extending the tip part of common lead 50 up to the neck part 2a of glass bulb 2 in the same way as the vibration-resistant light bulb of Figure 19. By making common lead 50 a beam that is supported at both ends, shield 36 vibrates clockwise and anticlockwise centered on common lead 50. Figures 17(a) through (c) are figures for explaining the operation of an automobile light bulb (seventh embodiment) relating to the present invention, which are theoretical views for confirming the operation of vibration absorption by dipped beam filament 37. Figure 17(a) shows the vibration directions R1 and R2 of shield 36. Figure 17(b) shows how one leg 41 vibrates in the direction of arrow R1 when shield 36 vibrates in direction R1. As a result, the side of one coiled end part 40a of coil part 40 absorbs the vibration by twisting in the direction of arrow N1. Figure 17(c) shows how one leg 41 vibrates in the direction of arrow R2 when shield 36 vibrates in direction R2. As a result, the side of one coiled end part 40a of coil part 40 absorbs the vibration by twisting in the direction of arrow N2. Note that although the present invention third embodiment) may be effectively applied to vibration-resistant light bulbs wherein the tip of common lead 4 is secured to glass bulb 2 (see Figure 19), it can also be applied to ordinary light bulbs (see Figure 18). Although automobile light bulbs have been described in the first through seventh embodiments above, these automobile light bulbs can naturally be applied not just to automobiles but also to vehicles such as motor cycles and electric trains.

Claims: Vehicle light bulb wherein a common lead (4), a dipped beam filament (26), a lead (7) for the use thereof, a main beam filament and a lead for the use thereof are accommodated inside a glass bulb (2) and a shield (25) is fixed to said common lead (4) along the dipped beam filament (26), characterized in that said shield (25) comprises a cup part (27) and a tongue part (28) that is fixed extending from said cup so as to pass through roughly the center of the bulb, and in that one leg (26a) of the dipped beam filament (26) is fixed to the center of the tongue part (28) in the width direction of the tongue part at roughly the central position of the glass bulb. Vehicle light bulb wherein a common lead (35), a dipped beam filament (37), a lead (7) for the use thereof, a main beam filament and a lead for the use thereof are accommodated inside a glass bulb and a shield (36) is fixed to said common lead (35) along the dipped beam filament (37), characterized in that said dipped beam filament (37) consists of a coil part (40) comprising a conductor formed in the shape of a coil spring, one leg (41) that extends out in a straight line from one end of the coil part (40) along a line that is tangential to the coils of this coil part (40), and another leg (42) that extends out in a straight line from the other end of the coil part (40) along a line that is tangential to the coils of this coil part (40) and is perpendicular to this one leg (41), and in that the one leg (41) is fixed to said shield (36) and the other leg (42) is fixed to the dipped beam filament lead (7). Vehicle light bulb according to claim 2, characterized in that said shield (45) is provided with a tongue part (45a) for fixing the other leg. Vehicle light bulb wherein a common lead (35), a dipped beam filament (37), a lead (47) for the use thereof, a main beam filament and a lead for the use thereof are accommodated inside a glass bulb and a shield (15) is fixed to said common lead (35) along the dipped beam filament (37), characterized in that said dipped beam filament (37) consists of a coil part (40) comprising a conductor formed in the shape of a coil spring, one leg (41) that extends out in a straight line from one end of the coil part (40) along a line that is tangential to the coils of this coil part (40), and another leg (42) that extends out in a straight line from the other end of the coil part (40) along a line that is tangential to the coils of this coil part (40) and is perpendicular to this one leg (41), and in that the one leg (41) is fixed to said common lead (35) and the other leg (42) is fixed to the dipped beam filament lead (47).

Inventors: HASEGAWA TORU, TABATA HAJIME, HASEGAWA, TORU, TABATA, HAJIME, Hasegawa, Toru, c/o KK Honda Gijutsu Kenkyusho, Tabata, Hajime, c/o KK Honda Gijutsu Kenkyusho
Applicants: HONDA MOTOR CO LTD, HONDA GIKEN KOGYO KABUSHIKI KAISHA
Application year: 1997
Main classification: H01K1
IPC codes: F21S8, H01K9, H01K1