Power converter and illumination device using the power converter

A power converter includes a mounting substrate, a one-piece-type connector including an input connector and an output connector, the input connector and the output connector being formed in one-piece and arranged side by side; and a case made of an electrically conductive material. The one-piece-type connector includes lead terminals configured to connect the input cable and the output cable to a power converting circuit and an electrically conductive ground connection portion electrically connected to the case through an electrically conductive member. The ground connection portion includes a shield surface arranged to extend along at least a portion of a side surface of the output connector.

FIELD OF THE INVENTION

The present invention relates to an illumination device that makes use of a power supply device including a power converter and, more particularly, to an EMS (Electromagnetic Susceptance) countermeasure technology for increasing a noise resistance of the power converter.

BACKGROUND OF THE INVENTION

Along with the generalization of an HID (High Intensity Discharge) lamp for motor vehicles, there is an increasing demand for the reduction of a size and a weight of a head lamp unit for the HID lamp. This holds true in case of an LED head lamp unit for motor vehicles.

The head lamp unit includes a head lamp portion and a power supply device. The head lamp portion is a lighting device for emitting light. The head lamp portion includes a socket to which a HID lamp is attached and an ignitor connected to the socket. The power supply device includes a battery power supply and a voltage converter for converting a voltage of the electric power supplied from the battery power supply and outputting the electric power to the ignitor. The voltage converter includes an input connector to which an input cable for supplying the electric power from the battery power supply is connected and an output connector to which an output cable for outputting the electric power to the ignitor is connected. In recent years, with a view to reduce the size of a head lamp unit and to save costs, there is known a power converter that makes use of a one-piece-type connector in which two input and output connectors are one-piece formed with each other (see, e.g., Japanese Patent Application Publication No. 2003-132979). There is also known a power converter in which a mounting substrate of a power converter circuit having input and output connectors is fixed to an accommodation case by screws (see, e.g., Japanese Patent No. 4479369)

The aforementioned power converter circuit is typically formed of an inverter, a chopper circuit and so forth. It is known that, depending on a loop antenna model or the like, the power converter circuit tends to generate a radiation noise affecting an output voltage. In order to reduce the size of the power converter, however, it is required to remove an unnecessary noise or to suppress the influence of the radiation noise at a significantly high level. In the event that an input connector and an output connector are one-piece formed with each other, the electric power inputted to the input connector is highly susceptible to a noise contained in the electric power outputted from the output connector. This is one of the causes hindering the size reduction of the power converter employing a one-piece-type connector.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a power converter capable of reducing the size of a one-piece-type connector and capable of increasing an EMS resistance, and an illumination device using the power converter.

In accordance with one aspect of the present invention, there is provided a power converter, including: a mounting substrate mounted with a power converting circuit for converting electric power supplied from a power supply and supplying the converted electric power to a load; a one-piece-type connector including an input connector by which an input cable for inputting the electric power supplied from the power supply to the power converting circuit is connected to the mounting substrate and an output connector by which an output cable for outputting the converted electric power to the load is connected to the mounting substrate, the input connector and the output connector being formed in one-piece and arranged side by side; and a case made of an electrically conductive material and configured to accommodate the mounting substrate and the one-piece-type connector, wherein the one-piece-type connector includes lead terminals configured to connect the input cable and the output cable to the power converting circuit and an electrically conductive ground connection portion electrically connected to the case through an electrically conductive member, the ground connection portion including a shield surface arranged to extend along at least a portion of a side surface of the output connector.

Preferably, the one-piece-type connector may further include a connecting portion to interconnect the input connector and the output connector, the ground connection portion including a base portion installed on the connecting portion and an upstanding portion standing up from the base portion to extend along a side surface of the output connector, the upstanding portion serving as the shield surface.

Preferably, the electrically conductive member may include a screw extending through the base portion and the mounting substrate to fix the ground connection portion to the case.

Preferably, the ground connection portion further may include leg portions extending from the base portion so as to make contact with the mounting substrate, each of the leg portions including a bent portion flexed depending on a difference in an attachment height of the lead terminals with respect to the mounting substrate.

Preferably, the electrically conductive member may include a grounding circuit formed on the mounting substrate, the leg portions making contact with the grounding circuit.

Preferably, the mounting substrate may have through-holes formed at adjacent positions with a mounting position of the connecting portion of the one-piece-type connector interposed therebetween, the ground connection portion including leg portions inserted into the through-holes and configured to fix the one-piece-type connector at a predetermined height by being locked to the through-holes in a state that the base portion is mounted to the connecting portion.

Preferably, the mounting substrate may have through-holes formed at adjacent positions with a mounting position of the connecting portion of the one-piece-type connector interposed therebetween, the leg portions being inserted into the through-holes and being configured to fix the one-piece-type connector at a predetermined height by being locked to the through-holes in a state that the base portion is mounted to the connecting portion.

Preferably, each of the lead terminals may include a crank-shaped bent portion flexed depending on a change in a distance between the one-piece-type connector and the mounting substrate.

Preferably, the crank-shaped bent portion of the lead terminal for the input connector and the crank-shaped bent portion of the lead terminal for the output connector may be oriented in mutually different directions.

Preferably, each of the lead terminals may have a tip end bent to extend along a surface of the mounting substrate so that the tip end is surface-mounted to the mounting substrate.

Preferably, the power converting circuit may include an inverter circuit.

In accordance with another aspect of the present invention, there is provided an illumination device, including: the power converter of above disclosed one aspect of the present invention; a power supply configured to supply electric power to the power converter; a lighting device as a load for receiving the electric power outputted from the power converter and emitting light; an input cable extending from the power supply, the input cable being connected to the input connector of the one-piece-type connector of the power converter; and an output cable extending to the lighting device, the output cable being connected to the output connector.

Preferably, the lighting device may include an igniter connected to the power converter and an HID lamp connected to the igniter.

With the present embodiment, the one-piece-type connector of the power converter includes a ground connection portion having a shield surface on at least a portion of the side surface near the output connector. The ground connection portion guides an unnecessary radiation noise, which would otherwise be inputted from the output connector to the input connector, toward the case. It is therefore possible to increase the EMS resistance of the power converter and to reduce the size of the one-piece-type connector.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a section view showing an HID head lamp unit1that makes use of a power converter6in accordance with one embodiment of the present invention.FIG. 2is a schematic circuit diagram of the HID head lamp unit1. The HID head lamp unit1includes a power supply device2and a head lamp portion3. The power supply device2includes a vehicle-mounted battery4having an output power of 12 V and a power converter6to which DC power is inputted from the battery4through a switch SW and an input cable5. The power converter6includes a DC/AC converting circuit16including an inverter circuit as a power converting circuit. The power converter6converts a DC voltage of 12 V to a high-frequency AC voltage having a frequency of 20 kHz to 100 kHz and outputs the AC voltage thus converted.

The head lamp portion3is a lighting device for emitting light. The head lamp portion3includes a HID lamp7, a socket8, an ignitor9supplying electric power to the socket8, an output cable10, a reflecting plate11, a lamp case12accommodating the components mentioned just above, and a light lens13. The HID lamp7is mounted to the socket8. The output cable10interconnects the power converter6and the ignitor9. The power converter6includes a one-piece-type connector17in which an input connector18connected to the input cable5and an output connector19connected to the output cable10are arranged in adjacent positions and are one-piece formed with each other. The ignitor9increases the output voltage of the power converter6to about 25 kV and outputs the voltage thus increased. In the head lamp unit1, other configurations than the power converter6is well-known in the art and will not be described in detail herein.

FIG. 3Ais a perspective view of the power converter6andFIG. 3Bis an exploded perspective view of the power converter6. The power converter6includes a mounting substrate14having an electric insulation property, an aluminum-die-cast case15as an electrically conductive member for accommodating the mounting substrate14, and a case cover30for covering the case15. The case15has screw holes15a,15band15cused in attaching the power converter6to an attachment frame of a motor vehicle or the like not shown in the drawings. The case15serves as a grounding mechanism with respect to the mounting substrate14.

The DC/AC converting circuit16and the one-piece-type connector17, to which the input and output cables (the cables5and10shown inFIG. 2) are connected, are mounted to the mounting substrate14. The one-piece-type connector17includes an input connector18to which the input cable5shown inFIG. 2is connected, an output connector19to which the output cable10is connected, a connecting portion20for interconnecting the two connectors18and19, and a ground connection portion21. The ground connection portion21, the connecting portion20, and the mounting substrate14have through-holes21b,20aand14ainto which screws22are inserted. In the following description, for the sake of convenience in description, the structure formed of the input connector18, the output connector19, and the connecting portion20will be referred to as a body of the one-piece-type connector17.

The ground connection portion21provided above the connecting portion20has a shield surface21astanding up along a portion of the side surface of the output connector (seeFIG. 4Ato be described later). The ground connection portion21is fixed to the one-piece-type connector17by inserting a set screw22as an electrically conductive member into the through-hole21bof the ground connection portion21, the through-hole20aof the connecting portion20, and a through-hole14aof the mounting substrate14and then tightening the set screw22to a thread hole15dof the case15. Since the ground connection portion21is connected to the electrically conductive case15by the set screw22, the unnecessary radiation noise outputted from the output connector19is guided toward the case15by the ground connection portion21. This reduces the influence of the unnecessary radiation noise on the input connector18. Accordingly, it is possible to shorten the distance between the input connector18and the output connector19. As a result, it becomes possible to reduce the size of the power converter6employing the one-piece-type connector17.

Due to the vibration transmitted from a motor vehicle to which the head lamp unit1is attached, the one-piece-type connector17may be applied with a pulling force through the cables5and10connected to the input connector18and the output connector19.

Since the one-piece-type connector17is screw-fixed to the case15, the one-piece-type connector17has an increased resistance against the pulling force. Since the ground connection portion21is directly connected to the case15, there is provided an advantage that an unnecessary antenna loop as a cause of generating a noise is not formed in the mounting substrate14.

Description will now be made on a manufacturing method of the power converter6. First, the lead terminals (seeFIG. 5) of the body of the one-piece-type connector17are mounted into the through-holes of the mounting substrate14. Then, the ground connection portion21, the body of the one-piece-type connector17and the mounting substrate14are fixed to the case15by the screw22. Thereafter, the mounting substrate14is potted (heaped) with a filler material. After the filler material is cured, the case cover30is attached to the case15by inserting the screw31through the case cover30and tightening the screw31to the thread hole32. The power converter6is manufactured in the aforementioned order.

FIG. 4Ais a perspective view showing the configuration of the ground connection portion21.FIG. 4Bis a perspective view for explaining how to attach the ground connection portion21to the body of the one-piece-type connector17.FIG. 4Cis a perspective view of the one-piece-type connector17mounted to the mounting substrate14. The ground connection portion21includes a base portion21cinstalled on the connecting portion20, an upstanding portion having a shield surface21astanding up from the base portion21calong the side surface of the connecting portion20of the output connector19, and plate-like leg portions21dand21e. The shield surface21ais arranged on at least a portion of the side surface of the output connector19. For example, the shield surface21amay stand up so as to extend along the surface of the leg portion21dor21e. Since the shield surface21ais arranged to exist between the input connector18and the output connector19as shown in the drawings, it is possible to effectively reduce the influence of a noise on the input connector18. The mounting substrate14includes a rectangular grounding wiring line14b(hatched inFIG. 4C) through which the through-hole14aextends. The grounding wiring line14bis an electrically conductive member differing from the screw22. The leg portions21dand21eextend from the base portion21ctoward the mounting substrate14and have a length large enough to make contact with the grounding wiring line14b. The one-piece-type connector17has slit-shaped grooves17aand17b(seeFIG. 5A) to which the leg portions21dand21eare fitted when the base portion21cof the ground connection portion21is placed on the connecting portion20. The leg portions21dand21ehave lug portions21fand21gformed at the opposite sides thereof. The lug portions21fand21gare locked inside the grooves17aand17bto fix the ground connection portion21to the one-piece-type connector17.

The ground connection portion21is connected to the case15through the screw22. Since the leg portions21dand21emake contact with the grounding wiring line14b, the noise grounding route is increased and the electric resistance is reduced. This makes it possible to stably reduce the noise. The grounding wiring line14bis preferably formed into a linear shape including the through-hole14aas shown inFIG. 4C, so as not to form an antenna loop as a cause of generating an unnecessary noise.

The one-piece-type connector17includes lead terminals23athrough23garranged on the lower surface thereof (seeFIG. 5A). The lead terminals23athrough23gextend so that one ends thereof can be electrically connected to the connectors of the input cable5and the output cable10and the other ends thereof can be inserted into the through-holes formed in the mounting substrate14. The other ends of the lead terminals23athrough23gare mounted (soldered) to the mounting substrate14through through-holes formed in the mounting substrate14. Then, the ground connection portion21is attached to the connecting portion20by the screw22. The leg portions21dand21einclude bent portions21hand21iformed at the tip ends thereof so that the bent portions21hand21ican be flexed when the ground connection portion21is pressed downward. The bent portions21hand21iare flexed depending on the difference in the installation height of the lead terminals23athrough23gattributable to the manufacturing error or the use environment. Thus the bent portions21hand21ikeep the lead terminals23athrough23gin good contact with the grounding wiring line14b. While the bent portions21hand21iare connected to the grounding wiring line14bby pressure contact, it may be possible to solder the bent portions21hand21ito the grounding wiring line14bafter the ground connection portion21is installed in place.

FIG. 5Ais a perspective view showing the lead terminals23athrough23gof the one-piece-type connector17.FIG. 5Bis a side view showing the one-piece-type connector attached to the mounting substrate14. Since the respective lead terminals23athrough23gare identical in shape, only the lead terminal23awill be described herein below. As shown inFIGS. 5A and 5B, the lead terminal23aincludes a crank-shaped bent portion23hextending parallel to the mounting substrate14. When the ground connection portion21is attached to the connecting portion20by the screw22, the leg portions21dand21eof the ground connection portion21exert forces by which the body of the one-piece-type connector17is urged to move away from the mounting substrate14. However, the crank-shaped bent portion23his flexed to absorb the forces, thereby preventing the lead terminal23afrom being separated from a solder. Similarly, the crank-shaped bent portion23hcan prevent the lead terminal23afrom being separated from a solder, in the event that the distance between the body of the one-piece-type connector17and the mounting substrate14is changed depending on the use environment after the bent portions21hand21iare soldered to the grounding wiring line14b. The distance change caused by the use environment is generated by, e.g., the temperature change or the vibration transmitted from a motor vehicle to which the case15is attached. While the opposite ends of the crank-shaped bent portion23hare bent at 90 degrees, they may be bent at an obtuse angle as long as the function of the crank-shaped bent portion23hflexed depending on the change in the distance between the connector17and the mounting substrate14is not impaired. The crank-shaped bent portions of the lead terminals23athrough23dof the input connector18and the crank-shaped bent portions of the lead terminals23ethrough23gof the output connector19may be oriented in the same direction or may be oriented in different directions, e.g., in 90-degree different directions as shown inFIG. 5A. This makes it possible to reduce the change in the posture of the one-piece-type connector17caused by the lead terminal23abeing flexed.

FIG. 6is a perspective view illustrating how to connect the output cable10to the output connector19of the one-piece-type connector17. The output cable10includes a shield member24arranged at the tip end thereof to completely cover the output connector19.FIG. 7is a section view of the output cable10taken along line VII-VII inFIG. 6.

The shield member24of the output cable10includes a connection member24aprotruding inward. Upon inserting a connector25of the tip end of the output cable10into the output connector19of the one-piece-type connector17, the connection member24ais connected to the shield surface21aof the ground connection portion21. If the shield surface21aof the ground connection portion21is formed on only the side surface of the output connector19facing the connecting portion20, the output cable10having the shield member24reduces the influence of a noise on the signal flowing not only through the input connector18but also through the wiring line of the mounting substrate14. If the shield surface of the ground connection portion21is formed to surround the side surface of the output connector19, the same noise reduction effect can be obtained even when an output cable not provided with the shield member24is used in place of the output cable10. For the sake of understanding of the invention,FIG. 7shows a state that the ground connection portion21and the grounding wiring line14bof the mounting substrate14are electrically connected to the thread hole15dof the case15by the screw22.

As described above, the power converter6is configured to increase the EMS resistance of the one-piece-type connector17using the ground connection portion21and to reduce the size of the one-piece-type connector17. It is also possible to reduce the overall size of the head lamp unit1as an illumination device employing the power converter6. Since the one-piece-type connector17and the ground connection portion21are directly attached to the case15by use of the screw22, the length of the grounding wiring line is reduced and the generation of the unnecessary noise is prevented. Since the one-piece-type connector is directly connected to the case, the one-piece-type connector has an increased resistance against the pulling force of the cables connected to the input connector18and the output connector19. Since one or both of the ground connection portion21and the lead terminals23athrough23gis provided with the bent portions, the solder portions of the ground connection portion21and the lead terminals23athrough23gare applied with low stresses and are prevented from being separated from the mounting substrate14.

Preferably, the one-piece-type connector17and the ground connection portion21are directly attached to the case15by use of the screw22. Considering the circuit design of the mounting substrate14, it may be possible to employ a configuration in which the one-piece-type connector17and the ground connection portion21are attached to the mounting substrate14by the screw22and then connected to the case15by way of one or both of the screw22and the leg portions21dand21e. In this case, it is possible to obtain the noise reduction effect provided by the ground connection portion21. Since one or both of the ground connection portion21and the lead terminal17bof the one-piece-type connector17is provided with the bent portions, the solder portions of the ground connection portion21and the lead terminals23athrough23gare applied with low stresses and are prevented from being separated from the mounting substrate14.

FIRST MODIFIED EXAMPLE

FIG. 8Ais a perspective view showing a ground connection portion26in accordance with a first modified example.FIG. 8Bis a perspective view of the one-piece-type connector17to which the ground connection portion26is mounted. The ground connection portion26includes a pair of leg portions26aand26bdiffering in shape from the ground connection portion21described above.FIG. 8Cis a section view showing the leg portions26aand26battached to the mounting substrate14. The mounting substrate14includes a pair of through-holes14cand14dformed at adjacent positions with the mounting position of the connecting portion20interposed therebetween. The tip ends of the leg portions26aand26bcome close toward each other so that the leg portions26aand26b, when inserted into the through-holes14cand14d, grip the mounting substrate14and fix the body of the one-piece-type connector17at a predetermined height. For the removal-preventing purpose, the leg portions26aand26bare provided at the tip ends with locking portions26cand26dbent such that locking portions26cand26dextend toward each other and then extend away from each other. The ground connection portion26is formed of an electrically conductive spring member having a thickness of, e.g., 0.4 mm or less. Since the one-piece-type connector17mounted with the ground connection portion26is fixed to the mounting substrate14at the predetermined height, it is possible to prevent the body of the one-piece-type connector17from floating when the lead terminals23athrough23gare soldered. In other words, the locking portions26cand26dhave an advantage in that there is no need to use a jig for tentatively pressing the body of the one-piece-type connector17and preventing the floating of the body of the one-piece-type connector17.

If the grounding wiring line14bis not formed on the mounting substrate14and if the ground connection portion26is not soldered to the mounting substrate14, the locking portions26cand26dare arranged in such positions where the locking portions26cand26dcan move up and down by a little distance (e.g., 0.1 mm) in a state that the ground connection portion26grips the mounting substrate14. The portions movable in the up-down direction have an advantage in that they can absorb the stresses attributable to the change in the distance between the one-piece-type connector17and the mounting substrate14when the one-piece-type connector17and the mounting substrate14are fixed to the case15by the screw22and when the illumination device is normally used. Even if the grounding wiring line14bis formed on the mounting substrate14, there is provided an advantage in that, after the one-piece-type connector17is attached to the case15, the ground connection portion26can be soldered to the mounting substrate14in such a position where the ground connection portion26does not apply any load on the soldered portions of the lead terminals23athrough23g.

The locking portions26cand26dmay have other well-known shapes as long as the aforementioned advantages can be provided by fixing the body of the one-piece-type connector at the predetermined height while assuring the easy insertion of the locking portions26cand26dinto the through-holes14cand14d. Instead of gripping the mounting substrate14, the locking portions26cand26dmay have, e.g., a snap-fit shape so that the locking portions26cand26dcan pass through the through-holes14cand14dand can interpose the front and rear surfaces of the mounting substrate14therebetween.

A curved portion having a U-like cross-sectional shape or a crank-shaped bent portion having the same shape as the crank-shaped bent portion23hof the lead terminal23amay be formed in the region of each of the leg portions26aand26bnearer to the base end than the locking portions26cand26d. In this case, it is possible to further enhance the ability to absorb the stresses attributable to the change in the distance between the one-piece-type connector17and the mounting substrate14.

SECOND MODIFIED EXAMPLE

FIG. 9Ais a perspective view of a one-piece-type connector27in accordance with a second modified example, which has lead terminals27athrough27gnot through-hole-mounted but surface-mounted to the mounting substrate14. InFIG. 9A, the lead terminal27ais shown on an enlarged scale.FIG. 9Bis a perspective view of the one-piece-type connector27surface-mounted to the double-side mounting substrate28. Other configurations of the one-piece-type connector27than the lead terminals, including the ground connection portion21or26, remain the same as the configurations of the one-piece-type connector17. The lead terminals27athrough27gare identical in configuration. Description will now be made on the lead terminal27a. The lead terminal27aincludes not only a crank-shaped bent portion27hflexed to absorb the change in the distance between the lead terminal27aand the double-side mounting substrate28but also a surface-mounted bent portion27iwhich is bent to extend along the surface of the substrate28. With this configuration, the one-piece-type connector27is surface-mounted to the substrate28.

The configurations of the power converter in accordance with the present invention are not limited to the configurations of the embodiment and the modified examples described above but may be modified in many different forms without departing from the scope and spirit of the invention. For example, contact points connected to the grounding wiring line may be formed inside the through-holes14cand14dof the mounting substrate14. The locking portions of the ground connection portion26may not be soldered to the substrate. In this case, the locking portions26cand26dare movable in the up-down direction. This provides an advantage in that it is possible to reduce the stresses applied to the lead terminals of the one-piece-type connector17and to increase the grounding route.

The power converter in accordance with the present invention can find its application not only in a motor vehicle but also in a variety of illumination devices that require an increased resistance against the noise generated in a power converting circuit.

While the invention has been shown and described with respect to the embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.