JP2010257848A - Vehicular headlight - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular headlight capable of securing higher maximum light-emitting brightness. <P>SOLUTION: In a discharge lamp 8, an external tube 18 mounted on a socket 17, a ceramic light-emitting tube 19 composed of a light-emitting part 20 and a pair of narrow tube parts 21, 21 sequentially installed at the light-emitting part on a side opposite to the light-emitting part, and arranged inside of the external tube, and a pair of electrodes 24, 25 arranged inside the ceramic light-emitting tube are installed. The ceramic light-emitting tube is formed by joining a first part 22 constituted of one narrow tube part and one part of the light-emitting part and a second part 23 constituted of the other narrow tube part and the part except one part of the light-emitting part, and the ceramic light-emitting tube is brought in a state of front-up inclination with respect to the horizontal direction in a state that the tip side is positioned upward or in a state of front-down inclination in a state that the tip side is positioned downward. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicle headlamp. Specifically, the present invention relates to a technical field in which a ceramic arc tube is inclined with respect to the horizontal direction to ensure high maximum light emission luminance.

  Vehicle headlamps include, for example, a type in which an incandescent lamp (incandescent bulb) or a halogen lamp (halogen bulb) is used as a light source, and a type in which a discharge lamp (discharge bulb) is used as a light source.

  For vehicle headlamps that use incandescent lamps or halogen lamps as the light source, the incandescent lamp or halogen lamp filaments emit light almost uniformly to form a rod-like light emitting part. When used as a lamp, there is an advantage that it is easy to perform light distribution control by the shape of the reflecting surface of the reflector.

  On the other hand, in a vehicle headlamp in which a discharge lamp is used as a light source, the discharge lamp has a larger amount of light than an incandescent lamp or a halogen lamp, so that the luminance can be improved. There is an advantage that the life of the discharge lamp is longer than that of the halogen lamp.

  As described above, since the discharge lamp has a higher luminance and a longer life as compared with the incandescent lamp and the halogen lamp, in recent years, a lamp equipped with a discharge lamp has become widespread as a vehicle headlamp.

  In a discharge lamp, a ceramic arc tube holding a pair of electrodes and filled with a gas such as a rare gas is disposed inside an outer tube, and the light emitting unit in which the ceramic arc tube discharges and the light emitting unit And a pair of thin tube portions provided on the opposite side with respect to each other. The light emitting portion is a portion where an arc is generated when discharge is performed, and is larger than the diameter of the narrow tube portion.

  In the discharge lamp, a predetermined starting voltage is applied to the pair of electrodes held in the ceramic arc tube, and lighting is started by discharging in the light emitting portion of the ceramic arc tube.

  In such a discharge lamp, the ceramic arc tube is formed by joining the first part and the second part, and the central part of the light emitting part is the joined part of the first part and the second part. There are some (see, for example, Patent Document 1).

  The ceramic arc tube is difficult to be formed by integral molding while ensuring the stability of the shape. As described above, a method of joining and forming two parts is widely used. Therefore, by joining and forming the two parts of the first part and the second part, it is possible to ensure the stability of the shape and reduce the manufacturing cost by facilitating the molding.

JP 2008-44344 A

  By the way, in the ceramic arc tube having no joint portion, the light emission luminance is maximized in the central portion of the light emitting portion, that is, in the central portion between the pair of electrodes, and in particular, in order to ensure sufficient distant visibility. It is possible to ensure the maximum light emission luminance of a necessary size.

  However, in the conventional discharge lamp described in Patent Document 1, since the joint is formed at the center of the light emitting part, the light is diffused by the joint and the emission luminance is lowered, which is necessary. There is a problem that it is not possible to secure a maximum light emission luminance of a large size.

  Therefore, an object of the vehicle headlamp of the present invention is to ensure a high maximum light emission luminance.

  In order to solve the above-described problems, a vehicle headlamp includes a discharge lamp that is continuously provided on the light emitting portion on the opposite side of the light emitting portion and the light emitting portion between the outer tube attached to the socket. A ceramic arc tube arranged inside the outer tube and a pair of electrodes arranged inside the ceramic arc tube, the ceramic arc tube being one of the narrow tube portions And the first part constituted by a part of the light emitting part, the other thin tube part and the second part constituted by a part other than the part of the light emitting part are joined and formed, The ceramic arc tube is inclined with respect to the horizontal direction in a state where the tip side is in a front-up position where the tip side is located upward or in a state where the tip side is located in a downward direction.

  Therefore, in the vehicular headlamp, the ceramic arc tube is turned on and tilted with respect to the horizontal direction to emit light.

  The vehicle headlamp according to the present invention is a vehicle headlamp in which a discharge lamp is used as a light source, and the discharge lamp is an outer tube attached to a socket, a light emitting portion, and an opposite portion sandwiching the light emitting portion. A ceramic arc tube arranged inside the outer tube, and a pair of electrodes arranged inside the ceramic arc tube, comprising a pair of thin tube portions provided continuously on the light emitting portion on the side, The ceramic arc tube has a first portion constituted by one of the thin tube portions and a part of the light emitting portion, and a second portion constituted by a portion other than the other portion of the thin tube portion and the light emitting portion. The ceramic arc tube is inclined with respect to the horizontal direction in a state where the tip end side is raised upward and the tip end side is lowered forward.

  Therefore, it is possible to ensure the maximum light emission luminance of a required size without being affected by the diffusion of light at the joint portion, and it is possible to ensure sufficient visibility in the distance.

  In a second aspect of the present invention, lighting is performed by supplying a direct current to the pair of electrodes, and the ceramic arc tube is tilted with respect to the horizontal direction in a front-up state.

  Therefore, it is possible to suppress a decrease in the temperature on the cathode side with respect to the temperature on the anode side, and it is possible to improve the luminous efficiency by suppressing the nonuniformity of the temperature distribution of the ceramic arc tube.

  In the invention described in claim 3, the position where the first portion and the second portion are joined is set to the tip side from the center between the pair of electrodes in the light emitting portion.

  Therefore, it is possible to widen the range of the region where the light emission luminance is high, and it is possible to easily form a light distribution pattern that requires light emitted from the discharge lamp.

  The best mode for carrying out the vehicle headlamp of the present invention will be described below with reference to the accompanying drawings.

  The vehicle headlamp 1 is mounted and arranged at both left and right ends of the front end of the vehicle body.

  As shown in FIG. 1, the vehicle headlamp 1 includes a lamp housing 2 having a recess opened forward, and a cover 3 that closes an opening surface of the lamp housing 2. A lamp outer casing 4 is configured. An internal space of the lamp outer casing 4 is formed as a lamp chamber 5.

  An insertion hole 2 a penetrating in the front-rear direction is formed at the rear end of the lamp housing 2, and the insertion hole 2 a is closed by a back cover 6. An arrangement hole 2b penetrating vertically is formed in the lower end portion of the lamp housing 2.

  A reflector 7 is supported in the lamp chamber 5 so as to be tiltable by an optical axis adjusting mechanism (not shown). A mounting hole 7 a penetrating in the front-rear direction is formed at the rear end of the reflector 7.

  A discharge lamp 8 is attached to the attachment hole 7 a of the reflector 7.

  A discharge lamp lighting device 9 is attached to the arrangement hole 2 b of the lamp housing 2. The discharge lamp lighting device 9 is configured by housing a lighting circuit (not shown) inside the case body 10. An input side connector 11 is provided on the outer peripheral surface of the case body 10, and an output side connector 12 is provided on the upper surface of the case body 10. The input side connector 11 is connected to a power supply circuit (not shown).

  The output-side connector 12 is connected to the starting device 14 via the power supply cord 13, and the connector 14 a of the starting device 14 is connected to a socket (described later) of the discharge lamp 8.

  For lighting the discharge lamp 8, the power supply voltage of the power supply circuit is boosted by the lighting circuit of the discharge lamp lighting device 9 and, for example, orthogonally transformed into a lighting voltage (starting voltage) which is a high-voltage AC voltage. Is applied to the discharge lamp 8 via the power supply cord 13 and the starting device 14.

  The lamp chamber 5 is provided with an extension 15 for shielding a part of the components arranged in the lamp chamber 5. The lamp chamber 5 is provided with a shade (not shown) that shields part of the light emitted from the discharge lamp 8.

  The discharge lamp 8 is configured by connecting a main body 16 to a socket 17 (see FIG. 2).

  The main body 16 has an outer tube 18 and a ceramic arc tube 19 disposed inside the outer tube 18.

  The outer tube 18 is formed by integrally forming, for example, quartz glass, a closing portion 18a that covers the ceramic arc tube 19 and the like, and a holding portion 18b that protrudes forward from the front end portion of the closing portion 18a.

  The ceramic arc tube 19 is formed by a light emitting portion 20 and thin tube portions 21 and 21 that are continuous at both front and rear ends of the light emitting portion 20, respectively. The thin tube portions 21 and 21 are each formed in a substantially cylindrical shape extending substantially front and rear, and have an outer diameter smaller than the outer diameter of the light emitting portion 20.

  Inside the light emitting section 20, a metal halide and a rare gas such as xenon or argon are sealed.

  The ceramic arc tube 19 is formed by joining a first portion 22 and a second portion 23. The first portion 22 is formed by integrally forming the narrow tube portion 21 located on the front side and the front half portion of the light emitting portion 20, and the second portion 23 is composed of the narrow tube portion 21 located on the rear side and the light emitting portion 20. The rear half is formed integrally.

  By joining the first portion 22 and the second portion 23 to the ceramic arc tube 19, a joint portion 20 a having a concavo-convex shape is formed at the center portion in the front-rear direction of the light emitting portion 20.

  The ceramic arc tube 19 is inclined with respect to the horizontal direction (H shown in FIGS. 1 and 2) in a front-up state where the tip side is positioned upward. Note that the ceramic arc tube 19 may be inclined with respect to the horizontal direction H in a state in which the front end side is lowered downward.

  A front electrode 24 and a rear electrode 25 that are formed long in the front-rear direction are arranged inside the thin tube portions 21, 21. The rear end 24 a of the front electrode 24 and the front end 25 a of the rear electrode 25 are located inside the light emitting unit 20 of the outer tube 18.

  A first lead wire 26 is connected to the front end portion of the front electrode 24. The first lead wire 26 has a portion projecting forward from the inside of the ceramic arc tube 19 through the holding portion 18 b and projecting to the outside of the outer tube 18. A portion of the first lead wire 26 protruding to the outside of the outer tube 18 is bent in a predetermined direction, and a rear end portion is connected to a first connection terminal (not shown) provided in the socket 17.

  A portion of the first lead wire 26 is held by the holding portion 18 b of the outer tube 18, and an insulating sleeve 27 is attached to a portion excluding a portion of the portion protruding to the outside of the outer tube 18. The insulating sleeve 27 is made of an insulating material such as glass or ceramic.

  A second lead wire 28 is connected to the rear end portion of the rear electrode 25. The rear end portion of the second lead wire 28 is connected to a second connection terminal (not shown) provided in the socket 17.

  In the discharge lamp 8 configured as described above, when a lighting voltage (starting voltage) is applied to the front electrode 24 and the rear electrode 25 via the power supply cord 13 and the starting device 14, the light emitting portion of the ceramic arc tube 19 A discharge phenomenon occurs in 20 and lighting starts. At this time, in the discharge lamp 8, since the ceramic arc tube 19 is inclined with respect to the horizontal direction H, the emission luminance of the light emitted from the light emitting unit 20 is on the lower side in the light emitting unit 20. Maximum (maximum emission brightness).

  FIG. 3 to FIG. 6 are charts or graphs showing changes in light emission luminance and the like due to differences in the inclination angle of the ceramic arc tube 19. 3 to 6 when the ceramic arc tube 19 is tilted with respect to the horizontal direction H, the tilt angles are set to 1 °, 1.5 °, 5 °, 10 °, 11 ° and 15 °. I went.

  3 and 4 show that when the ceramic arc tube 19 is in a horizontal state during AC lighting when an alternating current is supplied, when the ceramic arc tube 19 is tilted in a forwardly rising state with respect to the horizontal direction H, and in the horizontal direction H The measured value when tilted in a state of being lowered forward is shown.

  5 and 6 show that when the ceramic arc tube 19 is in a horizontal state during direct current lighting when a direct current is supplied, when the ceramic arc tube 19 is inclined in a state of rising upward relative to the horizontal direction H, and in the horizontal direction H The measured value when tilted in a state of being lowered forward is shown.

  3 and 5, the “bulb light flux” is the outgoing light flux in the light emitting section 20 when light is emitted, and the “lamp light flux” is the front when the light emitted from the light emitting section 20 is irradiated. This is the luminous flux of light headed to. “Judgment” is based on whether “maximum emission brightness” has increased by 3% or more with respect to the value in the horizontal state (tilt angle 0 °), and “bulb light flux” or “lamp light flux” is in the horizontal state. This is based on whether or not there is a decrease of 3% or more with respect to the value at (inclination angle 0 °), and any one item of “maximum emission luminance”, “bulb luminous flux” and “lamp luminous flux” is the standard. When it was not satisfied, it was determined that good results were not obtained.

  In the graphs of FIGS. 4 and 6, the horizontal axis indicates the position in the light emitting unit 20, and the vertical axis indicates the luminance. The position of the light emitting unit 20 indicates the front position as “0” is the rear end of the light emitting unit 20 and the numerical value increases.

  As shown in FIGS. 4 and 6, when the ceramic arc tube 9 is tilted in the front-up state, the maximum emission luminance is generated on the rear end side of the light emitting unit 20, that is, on the lower side. . Further, when the ceramic luminous tube 9 is tilted in the front-down state, the maximum light emission luminance is generated on the front end side of the light emitting unit 20, that is, the side located below.

  In the graphs of FIGS. 4 and 6, there is a portion (a hollow portion) where the light emission luminance is sharply reduced in the central portion of the light emitting portion 20. It is caused by being diffused at 20a.

  In the AC lighting shown in FIG. 3 and FIG. 4, when the arc tube 19 is moved up, the “maximum emission luminance” is not increased by 3% or more at an inclination angle of 1 °, and the inclination angle is 11 °. At 15 ° and 15 °, the “bulb luminous flux” and “lamp luminous flux” decreased by 3% or more. On the contrary, good results were obtained for “maximum emission luminance”, “bulb luminous flux”, and “lamp luminous flux” at an inclination angle of 1.5 ° to 10 °.

  Further, in the AC lighting shown in FIGS. 3 and 4, when the arc tube 19 is lowered forward, the “maximum light emission luminance” does not increase by 3% or more at an inclination angle of 1 °, and the inclination angle is At 11 ° and 15 °, the “bulb luminous flux” and the “lamp luminous flux” decreased by 3% or more. On the contrary, good results were obtained for “maximum emission luminance”, “bulb luminous flux”, and “lamp luminous flux” at an inclination angle of 1.5 ° to 10 °.

  In the direct current lighting shown in FIGS. 5 and 6, when the arc tube 19 is moved up, the “maximum light emission luminance” does not increase by 3% or more at the tilt angle of 1 °, and the tilt angle is 11 °. At 15 °, the “lamp luminous flux” decreased by 3% or more. On the contrary, good results were obtained for “maximum emission luminance”, “bulb luminous flux”, and “lamp luminous flux” at an inclination angle of 1.5 ° to 10 °.

  Further, in the DC lighting shown in FIGS. 5 and 6, when the arc tube 19 is moved forward, the “maximum light emission luminance” does not increase by 3% or more at an inclination angle of 1 °, and the inclination angle is At 1.5 °, 5 °, 10 °, 11 ° and 15 °, the “bulb luminous flux” and the “lamp luminous flux” showed a decrease of 3% or more.

  As the inclination angle of the ceramic arc tube 19 with respect to the horizontal direction H is smaller, the position where the maximum light emission luminance is generated is more likely to overlap the joint 20a, and if it is too large, the minimum temperature (cold spot temperature) of the ceramic arc tube 19 becomes too low. As a result, the light emission luminance is reduced due to the reduction in light emission efficiency.

  Further, when the discharge lamp 8 is dc-lit, when the rear side of the discharge lamp 8 is an anode and the front side is a cathode, the temperature on the rear side, which is the anode, tends to increase. As also shown in the measurement results shown, it is desirable to incline the ceramic arc tube 19 in a state of rising forward so that the front side serving as the cathode is positioned upward. By tilting the ceramic arc tube 19 in a forwardly rising state, it becomes possible to suppress a decrease in temperature on the cathode side with respect to the temperature on the anode side, and to suppress non-uniformity in the temperature distribution of the ceramic arc tube 19. Thus, the luminous efficiency can be improved.

  Therefore, as shown in the measurement results of FIGS. 3 to 6 described above, in the case of alternating current lighting, the ceramic arc tube 19 is 1.5 ° in a state where the ceramic arc tube 19 is raised or lowered with respect to the horizontal direction H. It is considered that it is desirable that the ceramic arc tube 19 is inclined by 1.5 ° to 10 ° in a state of rising upward with respect to the horizontal direction H in the case of DC lighting.

  Further, in direct current lighting, when the ceramic arc tube 19 is tilted in a front-up state so that the front side which is the cathode is positioned upward, the joint 20a of the light emitting unit 20 is the center in the front-rear direction of the light emitting unit 20. It is desirable to form at a more forward position (see FIG. 7).

  By forming the joint portion 20a of the light emitting portion 20 at the front position in this way, it is possible to widen the range of the region A where the light emission luminance is high, as shown in FIG. 8, and the light emitted from the discharge lamp 8 Therefore, it is possible to easily form a required light distribution pattern.

  FIG. 9 shows that when the ceramic arc tube 19 is in a horizontal state during direct current lighting, it is tilted in a front-up state with respect to the horizontal direction H, and is tilted in a front-down state with respect to the horizontal direction H. The measured value is shown. The measurement of FIG. 9 was performed with the inclination angles set to 1 °, 1.5 °, 5 °, 10 °, 11 °, and 15 °.

  As shown in FIG. 9, in direct current lighting, when the ceramic arc tube 19 is tilted in a state of rising upward so that the front side is positioned upward, compared to the case where the ceramic arc tube 19 is horizontal, A large increase in the maximum emission luminance was observed. Accordingly, it has been demonstrated that in direct current lighting, it is desirable to incline the ceramic arc tube 19 in a state of rising upward so that the front side serving as the cathode is positioned upward.

  In the above, the case where the ceramic arc tube 19 is tilted with respect to the outer tube 18 is shown as an example of tilting the ceramic arc tube 19 with respect to the horizontal direction H. For example, as shown in FIG. It is also possible to attach the ceramic arc tube 19 to the reflector 7 in a state where the whole is inclined, and to incline the ceramic arc tube 19 with respect to the horizontal direction H.

  As described above, in the discharge lamp 8, the ceramic arc tube 19 is inclined with respect to the horizontal direction H with the front end rising upward and the front end falling downward. In the position corresponding to the joint 20a, the maximum light emission luminance does not occur, and the maximum light emission luminance occurs in the lower position when tilted.

  Therefore, the maximum light emission luminance of a required size can be ensured without being affected by the diffusion of light in the joint portion 20a, and sufficient distant visibility can be ensured.

  The shapes and structures of the respective parts shown in the best mode for carrying out the invention described above are merely examples of the embodiments performed in practicing the present invention. The range should not be interpreted in a limited way.

FIG. 2 to FIG. 10 show the best mode of the vehicle headlamp of the present invention, and this figure is a schematic sectional view of the vehicle headlamp. It is an enlarged side view of the discharge lamp which shows a part in cross section. It is a graph which shows the light emission luminance etc. by the difference in the inclination angle of the ceramic arc tube in alternating current lighting. It is a graph which shows distribution of the light emission brightness | luminance by the difference in the inclination angle of the ceramic arc tube in alternating current lighting. It is a graph which shows the light emission luminance etc. by the difference in the inclination angle of the ceramic arc tube in direct current lighting. It is a graph which shows distribution of the light emission luminance by the difference in the inclination angle of the ceramic arc tube in direct current lighting. It is an enlarged side view which shows the discharge lamp in which the position of the junction part was formed ahead from the center of the light emission part in a cross section. It is a graph which shows distribution of the light emission luminance in the discharge lamp in which the position of the junction part was formed ahead from the center of the light emission part. It is a graph which shows distribution of the light emission brightness | luminance by the difference in the inclination angle of a ceramic arc tube when the position of a junction part is formed ahead from the center of a light emission part. It is a schematic sectional drawing which shows the vehicle headlamp with which the whole discharge lamp was inclined with respect to the horizontal direction.

  DESCRIPTION OF SYMBOLS 1 ... Vehicle headlamp, 8 ... Discharge lamp, 17 ... Socket, 18 ... Outer tube, 19 ... Ceramic arc tube, 20 ... Light emission part, 21 ... Thin tube part, 22 ... 1st part, 23 ... 2nd Part 24 ... front electrode 25 ... rear electrode

Claims (3)

A vehicle headlamp in which a discharge lamp is used as a light source,
The discharge lamp is
An outer tube attached to the socket;
A ceramic arc tube disposed inside the outer tube, comprising a light emitting portion and a pair of thin tube portions provided continuously to the light emitting portion on the opposite side across the light emitting portion;
A pair of electrodes disposed inside the ceramic arc tube,
The ceramic arc tube has a first portion constituted by one of the thin tube portions and a part of the light emitting portion, and a second portion constituted by a portion other than the other portion of the thin tube portion and the light emitting portion. Is formed by joining
The vehicular headlamp characterized in that the ceramic arc tube is inclined with respect to a horizontal direction in a state where the tip end side is in a front-up position and the tip side is in a front-down position. A direct current is supplied to the pair of electrodes to perform lighting,
The vehicle headlamp according to claim 1, wherein the ceramic arc tube is inclined with respect to the horizontal direction in a state where the ceramic arc tube rises forward. The vehicle front according to claim 2, wherein a position where the first portion and the second portion are joined is set to the tip side from a center between the pair of electrodes in the light emitting portion. Lighting.

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