Abstract:
An electric discharge lamp device prevents a temperature rise in the circuit device when an electric discharge lamp ( 30 ) is operated without the use of a high voltage wire and a high voltage connector. The electric discharge lamp device includes a reflecting member ( 20 ) and a circuit device ( 40 ) that is directly connected with the electric discharge lamp ( 30 ) without using a high voltage wire. The distance between the reflecting member ( 20 ) and the circuit device ( 40 ) is set at a value not less than 6 mm. In operation, a beam of light emitted from the electric discharge lamp ( 30 ) is reflected forward by a concave reflecting face of the reflecting member ( 20 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electric discharge lamp device, the light source of which is an electric discharge lamp, in which the electric discharge lamp is directly connected with a circuit device for generating a high voltage to operate the electric discharge lamp. 
     2. Description of the Related Art 
     An electric discharge lamp device, the light source of which is an electric discharge lamp, is used for a headlight for vehicle use. In order to operate the electric discharge lamp, it is necessary to impress a high voltage upon the electric discharge lamp. Therefore, the electric discharge lamp is electrically connected with a circuit means, or circuit device, for generating a high voltage by a high voltage wire. 
     However, in the structure of connecting the electric discharge lamp with the circuit means device by the high voltage wire, it is necessary to shield the high voltage wire so as to prevent noise being generated by the high voltage wire. Further, in order to connect the high voltage wire with the electric discharge lamp, it is necessary to provide a high voltage connector. Accordingly, the manufacturing cost of the electric discharge lamp device is raised. 
     In order to solve the above problems, it is possible to use a structure in which the high voltage wire is not used and the electric discharge lamp and the circuit device are directly connected with each other to accomplish the electric connection as disclosed in Japanese Unexamined Patent Publication No. 10-228804. When the electric discharge lamp and the circuit device are directly connected with each other, it becomes unnecessary to use the high voltage connector and the high voltage wire. 
     However, when the electric discharge lamp and the circuit device are directly connected with each other and the circuit device is arranged close to the electric discharge lamp, the inner temperature of the circuit device is raised by the influence of conduction or radiation of heat generated by the electric discharge lamp and also by the influence of heat generated by the circuit device itself. Accordingly, there is a possibility of malfunction of circuit elements incorporated into the circuit device. 
     Further, according to Japanese Unexamined Patent Publication No. 10-228804, there is provided a bracket protruding from a rear face of the reflector of the electric discharge lamp, and the circuit device is supported by an end portion of the bracket. However, in this structure, heat generated by the electric discharge lamp stays around the circuit device because the bracket is arranged at an upper and a lower position of the circuit device. Accordingly, the temperature of the circuit device is significantly raised. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an electric discharge lamp device from which a high voltage wire and a high voltage connector are removed so that a temperature rise in the circuit device can be prevented by a simple structure. 
     According to the electric discharge lamp device of the first aspect of the present invention, an electric discharge lamp and a circuit device for impressing a high voltage upon the electric discharge lamp are directly connected with each other so that they are electrically connected. Accordingly, it becomes unnecessary to provide a high voltage connector and a high voltage wire for connecting the electric discharge lamp with the circuit device. 
     The structure of the electric discharge lamp device of the first aspect of the present invention will be described as follows. There is formed a gap between a face of the circuit device, which is opposed to the reflecting member, and the reflecting member. This gap formed between the face of the circuit device, which is opposed to the reflecting member, and the rear face of the reflecting member continues to a space formed by the reflecting member and the case. Accordingly, air rises when it is heated by the influence of heat generated by the electric discharge lamp and the circuit device. This rising air is not obstructed by the circuit device. Therefore, the thus heated air quickly moves upward. Accordingly, heat is not accumulated in a gap formed between the reflecting member and the circuit device. After the thus heated air has risen, the peripheral air flows into the gap by convection. 
     When a profile of the circuit device opposed to the reflecting member is restricted, it is possible to cool the circuit device by a simple structure and prevent the temperature of the circuit device from rising. 
     The structure of the electric discharge lamp device of the first aspect of the present invention will be described as follows. There is formed a gap between a face of the circuit means, which is opposed to the reflecting member, and the reflecting member. This gap formed between the face of the circuit means, which is opposed to the reflecting member, and the rear face of the reflecting member continues to a space formed by the reflecting member and the case. Accordingly, air rises when it is heated by the influence of heat generated by the electric discharge lamp and the circuit means. This rising air is not obstructed by the circuit means. Therefore, the thus heated air quickly moves upward. Accordingly, heat is not accumulated in a gap formed between the reflecting member and the circuit means. After the thus heated air has risen, the peripheral air flows into the gap by convection. 
     When a profile of the circuit means opposed to the reflecting member is restricted, it is possible to cool the circuit means by a simple structure and prevent the temperature of the circuit means from rising. 
     According to the second aspect of the present invention, the electric discharge lamp device includes: an attaching section protruding to the right and left from the circuit means; and a boss section, which is arranged in the reflecting member, protruding onto the attaching section side so that the boss section can be positioned to the attaching section, wherein the circuit means can be fixed to the reflecting means when the attaching section and the boss section are positioned to each other. Since the attaching section and the boss section are arranged so that the circulation of air in a gap formed between the reflecting member and the circuit means can not be obstructed, air which has been heated by the heat generated by the electric discharge lamp and the circuit means can quickly goes up in the gap between the reflecting member and the circuit means. Accordingly, it 
     According to the second aspect of the present invention, the electric discharge lamp device includes an attaching section protruding to the right and left from the circuit device and a boss section, which is arranged in the reflecting member, protruding onto the attaching section side of the reflecting member. In this configuration the boss section can be positioned adjacent to the attaching section so that the circuit device can be fixed to the reflecting means member. Since the attaching section and the boss section are arranged so that the circulation of air in a gap formed between the reflecting member and the circuit device is not obstructed, air which has been heated by the heat generated by the electric discharge lamp and the circuit device can quickly enter the gap between the reflecting member and the circuit device. Accordingly, it is possible to positively prevent a rise in the temperature of the circuit device. 
     According to the electric discharge lamp device of the third aspect of the present invention, a distance between the reflecting member and the circuit device is not less than 6 mm on the upper side of the connecting section at which the electric discharge lamp is connected with the circuit device. Therefore, the width of a passage for air can be ensured. Air, heated by the electric discharge lamp, and the circuit device, moves upward and into the passage. Accordingly, air can be quickly circulated by convection, and the circuit device can be effectively cooled. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above object and features of the present invention will be more apparent when the following description of the preferred embodiment is read with reference to the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional view showing a headlight of an embodiment of the present invention; 
     FIG. 2 is an exploded perspective view showing a headlight of the present embodiment; 
     FIG. 3 is a schematic illustration showing a circuit device of the present embodiment; 
     FIG. 4 is a schematic illustration showing a circuit device of the present embodiment; 
     FIG. 5 is a cross-sectional view showing a gap formed between the reflecting member and the circuit device of the present embodiment; and 
     FIG. 6 is a characteristic diagram showing a relation between the distance from the reflecting member to the circuit device and the temperature of the present embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the accompanying drawings, an embodiment of the present invention will be explained below. 
     FIGS. 1 and 2 are views showing an embodiment in which the electric discharge lamp of the present invention is applied to a headlight of a vehicle. The headlight  10 , which is an electric discharge lamp, includes a case  11 , a reflecting member  20 , an electric discharge lamp  30  and a circuit means, or circuit device  40 . The case  11  includes a case body  12 , a lens  13  and a cover  14  and houses a the reflecting member  20 , the electric discharge lamp  30  and the circuit device  40 . 
     The reflecting member  20  is a support member having a mechanism capable of adjusting the optical axis. This reflecting member  20  is movably supported by the case body  12 . The reflecting member  20  is made of resin and formed into a cup-shape. On the concave reflecting face of the reflecting member  20 , there is provided reflecting material by which a beam of light emitted from the electric discharge lamp  30  is reflected forward. On the rear face  24  side of the reflecting member  20 , there is provided a boss section  23  (shown in FIG. 2) to which the circuit device  40  is attached. 
     The electric discharge lamp  30  is inserted into the through-hole  20   a  of the reflecting member  20 . The shade  32  shuts off a beam of direct light, which proceeds forward, emitted from the electric discharge lamp  30 . The spring  25  is pivotally attached to the support section  21  formed on the outer circumference of the through-hole  20   a . When both ends of the spring  25  are engaged with a pair of pawls located on the opposite side of the support section  21  with respect to the through-hole  20   a , the spring  25  pushes the connector section  31  of the electric discharge lamp  30  against the reflecting member  20  in the periphery of the through-hole  20   a . When the contact face  31   a  of the connector section  31  on the electric discharge lamp  30  side comes into contact with the connector section side end face  20   b  provided in the reflecting member  20 , the electric discharge lamp  30  and the circuit device  40  can be positioned close to each other. 
     The circuit device  40  is provided with a circuit to impress a high voltage upon the electric discharge lamp  30 . When the connector section  41  of the circuit device  40  shown in FIG.  2  and the connector section  31  of the electric discharge lamp  30  are directly connected with each other, the electric discharge lamp  30  and the circuit device  40  can be electrically connected with each other. The connector section  31  and the connector section  41  form a connecting section in which the electric discharge lamp  30  and the circuit device  40  are connected with each other. The circuit device  40  has an attaching section  42  at positions corresponding to the two boss sections  23  symmetrically arranged in the traverse direction with respect to the center of the through-hole  20   a  of the reflecting member  20  so that the circuit member can be attached to the reflecting member  20 . When the attaching section  42  and the boss section  23  are positioned and fixed to each other by means of a screw, the circuit member is attached to the reflecting member  20   c    
     As shown in FIG. 3, the circuit device  40  may be provided with both the control circuit  40   a  and the starter circuit  40   b . Otherwise, as shown in FIG. 4, the circuit device  40  may be provided with only the starter circuit  40   b . The starter circuit  40   b  impresses a high voltage upon the electric discharge lamp  30  when the electric discharge lamp  30  is operated. The control circuit  40   a  controls electric power supplied to the electric discharge lamp  30 . 
     When the electric discharge lamp  30  and the circuit device  40  are incorporated to each other as shown in FIG. 1, the electric discharge lamp  30  and the circuit device  40  are not contacted with the case  11  but are movable with respect to the case  11 . Accordingly, it is possible to adjust the optical axis of the electric discharge lamp  30  manually or automatically. 
     The voltage of a battery, not shown, is impressed upon the circuit device  40  via an electric power source cord  50 . The electric power source cord  50  is connected with the circuit device  40  by the connector  51  and also connected with the battery side by the connector  52 . 
     Next, an explanation will be made into a relation between a distance “d” from the reflecting member  20  to the circuit device  40  and the inside temperature of the circuit device  40 . 
     Air in the gap  60  formed between the reflecting member  20  and the circuit device  40  is heated by the heat generated by the electric discharge lamp  30  and the circuit device  40  and moves upward in the perpendicular direction. As shown in FIG. 5, the opposite face  43  of the circuit device  40 , which is opposed to the reflecting member  20 , extends along a perpendicular face passing through a connecting position in the perpendicular direction at which the electric discharge lamp  30  and the circuit device  40  are connected with each other. The rear face  24  of the reflecting member  20  facing the circuit device  40  is convex. Accordingly, heated air in the gap  60  goes up in the perpendicular direction without being obstructed by the rear face  24  of the reflecting member  20  and the opposed face  43  of the circuit device  40 . As the space  61 , which is formed by the upper face  44  of the circuit device  40 , the cover  14  of a portion of the case  11  and the case body  12 , continues to the gap  60 , the heated airy which moves upward in the gap  60  in the perpendicular direction, smoothly flows into the space  61 . After hot air has moved upward, cold air in the periphery flows into the gap  60 . Therefore, a good convection of air is generated around the gap  60 . Due to the foregoing, heat is not accumulated in the gap  60  but the circuit device  40  is cooled. Therefore, the temperature of the circuit device  40  is prevented from rising. Accordingly, malfunction of the circuit elements in the circuit device  40  can be prevented. 
     As shown in FIG. 6 when the distance “d” between the reflecting member  20  and the circuit device  40  is decreased smaller than 6 mm, the inside temperature of the circuit device  40  is sharply raised. Therefore, it is preferable that the distance “d” is greater than or equal to 6 mm. 
     In this embodiment, when the entire opposed face  43  of the circuit device  40 , which is opposed to the reflecting member  20 , extends along the perpendicular face, a convection of air can be quickly performed. 
     The opposed face of the circuit device  40 , which is opposed to the rear face of the reflecting member  20 , is not limited to a plane. The opposed face of the circuit device  40  may be a curved face. Alternatively, the opposed face of the circuit device  40  may be protruded and recessed. That is, it is sufficient that a gap is formed between the reflecting member  20  and circuit device  40 . 
     In order to make the heated air easily move upward in the gap  60 , it is preferable that the support section  21 , which is formed on the rear face  24  of the reflecting member  20  and used for attaching the spring  25 , and the pawls  22  are made to come close to the rear face  24  so that the number of portions protruding into the circuit device  40  can be reduced.