Electric lamp and discharge devices: systems – Special application – Vehicle
Reexamination Certificate
2002-04-15
2004-01-20
Wong, Don (Department: 2824)
Electric lamp and discharge devices: systems
Special application
Vehicle
C315S058000
Reexamination Certificate
active
06680575
ABSTRACT:
TECHNICAL FIELD
The invention relates to a lamp holder holding a lamp such as a high-intensity discharge lamp and so on, which are used as automotive headlights.
BACKGROUND ART
Recent years have seen a tendency to shift from halogen lamps to high-intensity discharge lamps (hereafter, referred as HID) such as metal halide lamps, high-pressure sodium lamps, mercury-vapor lamps and so on in the area of the automobile headlights. There are reasons that the HID has advantage over the halogen lams in having a ray bundle larger, energy efficiency higher and wear characteristics longer than the halogen lamps. Such a discharge lamp-equipped lighting device includes the discharge lamp described above, an igniter performing the instantaneous high-voltage discharge, and a ballast controlling the igniter.
The lamp holder for holding the discharge lamp in the discharge lamp-equipped lighting device has high-voltage side and low-voltage side terminals. An insulating seal member providing electrical isolation between both terminals is disposed between both terminals in order to apply the high-voltage of approximately 30 kV to the lamp.
Concretely, the high-voltage side terminal connected to a high-voltage side of a lamp plug is disposed at a central section of the lamp holder. The low-voltage side terminal connected to a low-voltage side of the lamp plug is disposed at a section close to the outer periphery of the lamp holder. The insulating seal member insulating perfectly and electrically between both terminals is disposed between both terminals. It is possible to increase insulation and withstand voltage performance due to the insulating seal member to obtain a lamp to allow withstanding the high-voltage.
With the lamp, the insulating seal member is simply mated with an outer periphery of a cylindrical guide section enclosing the high-voltage side terminal. Therefore, when the discharge lamp is removed from the lamp holder in order to replace the lamp by new one, there may be cases where the insulating seal member is broken away from the lamp holder with the insulating seal member being adhered to the discharge lamp side. When a new discharge lamp is mounted on the lamp holder without becoming aware of the breakage of the insulating seal member, the new one is mounted on the lamp holder without using the insulating seal member. Therefore, there may be cases where the lighting device sustains damage owing to defective insulation.
To solve such a problem, it is known that another member is added to prevent the insulating seal member from being broken away from the lamp holder on removing the discharge lamp. For example, JP-A-64643/1998 discloses a lamp holder to ensure the fixation of the insulating seal member even when the lamp plug is removed from the lamp holder. With the lamp holder, a section to be equipped with a stopper is arranged at a section to be equipped with high-voltage terminal in order to keep the insulation and withstand voltage performance when a new lamp is mounted. It is possible to prevent the insulating seal member from being removed due to a stopper mounted on the section.
FIG. 1
is a cross sectional view of explaining a structure of preventing the insulating seal member from being removed from the discharge lighting device disclosed in the JP-A-64643/1998 described above. In the drawing, a reference numeral
1
denotes a discharge lamp, a reference numeral
2
denotes a lamp plug of the discharge lamp
1
, and a reference numeral
3
denotes a lamp holder having the functions of holding the discharge lamp
1
and of applying power thereto. A reference numeral
4
denotes a high-voltage side terminal for applying the high-voltage to the high-voltage side of the discharge lamp
1
, and a reference numeral
5
denotes a low-voltage side terminal connected to the low-voltage side of the discharge lamp
1
. A reference numeral
6
denotes a guide section integral with the lamp holder
3
to constitute an outer peripheral wall of the lamp holder
3
. The guide section
6
is formed vertically in a fit recess
3
a
for a lamp plug-fitted purpose. A fit section
2
a
of the lamp plug
2
includes a central section
2
b
making contact with the high-voltage side terminal
4
, and a peripheral section
2
c
enclosing the central section
2
b
and making contact with the low-voltage side terminal
5
. An inner peripheral wall
2
d
of the peripheral section
2
c
is tapered. A reference numeral
7
denotes an insulating seal member sheathed on the outer periphery of the guide section
6
in order to provide electrical isolation between the high-voltage and low-voltage sides. An outer peripheral wall
7
a
of the insulating seal member
7
is so reverse-tapered as to allow making contact with the inner peripheral wall
2
d
of the peripheral section
2
c
of the lamp plug
2
above. A reference numeral
8
denotes an approximately cylindrical-shaped stopper holding one end of the insulating seal member
7
. A circle section
8
a
of the stopper
8
projects outwardly from the one end of the stopper
8
in a radial direction thereof and makes into contact with an upper end of the guide section
6
.
A method of assembling parts will be explained hereafter. The insulating seal member
7
is sheathed on the outer periphery of the guide section
6
of the lamp holder
3
to obtain an assembled unit. The assembled unit is inserted into the lamp holder
3
, and then the insulating seal member
7
is held due to the circle section
8
a
of the stopper
8
.
However, since the conventional lamp holder is constituted as described above, it is necessary to add newly parts corresponding to the stopper
8
, for example, as another member for preventing the insulating seal member
7
from being removed from the discharge lighting device. The addition of parts leads to not only complicate the structure of the lamp holder to but also increase the cost of manufacturing the lamp holder.
With the conventional lamp holder, the insulating seal member
7
is molded of silicone rubber with flexibility. When the inner peripheral wall
2
d
of the lamp plug
2
adheres to the outer peripheral wall
7
a
of the insulating seal member
7
and the discharge lamp
1
is removed from the lamp holder, it is possible to prevent the insulating seal member
7
from being removed therefrom. However, since tear strength of the insulating seal member
7
is weak, the insulating seal member
7
facilitates turning and tearing in part and the correct insulation performance is not kept.
Moreover, with the conventional lamp holder, the guide section
6
is formed at the lamp holder
3
in one piece, and a projected peripheral section of the guide section
6
is higher than the guide section
6
. Therefore, there is possibility of impairing the workability of inserting the insulating seal member
7
into the guide section
6
.
The invention was made to solve the foregoing problems. Accordingly, it is an object of the invention to provide a lamp holder having a simple structure with improved workability without increasing a parts count. The lamp holder allows reduction of the cost of manufacture, and prevents the insulating seal member adhered to the lamp plug from being broken away from the lamp plug on removing the discharge lamp to replace it by new one. The lamp holder allows to preclude defective insulation caused by dropouts, displacements, entanglement or cracking of the insulating seal member on assembling new parts into the lamp holder, and prevent malfunctions such as damage of the lamp or no-lighting and so on.
DISCLOSURE OF THE INVENTION
In order to achieve the object of the invention, we provide a lamp holder comprising: a fit recess for a lamp plug-fitted purpose; a high-voltage side terminal arranged at any one of a central section of the fit recess and a peripheral section surrounding the central section of the fit recess; a low-voltage side terminal arranged at the other; and an insulation seal member insulating between the low-voltage side terminal and the high-voltage side member, wherein at least one
Sekiya Mutsuo
Ushio Hiroki
A Minh D
Mitsubishi Denki & Kabushiki Kaisha
Wong Don
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