JP2005203186A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the noise of a different frequency band while avoiding the enlargement of a discharge lamp lighting device and the complication of a circuit configuration in the discharge lamp lighting device suitable for a high luminance discharge lamp used for a head light of an automobile. <P>SOLUTION: A filter circuit 12 is constituted by connecting an impedance element Z between the neutral point of the series circuit of two capacitors C1, C2 and a ground. Since the noise component of the relatively low frequency band generated from an inverter 2 flows to the ground through the capacitors C1, C2 and the impedance element Z, the noise component does not leak out of the inverter 3. Since the noise component of the relatively high frequency band generated from the discharge lamp 2 returns toward the discharge lamp 2 through the capacitors C1, C2, the noise component can be suppressed to leak toward the inverter 3. Further, since the impedance element Z is necessary only to be added to a conventional example, the noise of a different frequency band can be suppressed while avoiding the size increase of the device and the complication of the circuit configuration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device, and more particularly to a discharge lamp lighting device suitable for a high-intensity discharge lamp used for a headlamp of an automobile.

  In recent years, high-intensity discharge lamps (HID bulbs) have been used as automotive headlamps because of safety advantages of higher brightness, lower power consumption, and longer life than conventional halogen bulbs. From large passenger cars to small passenger cars. (See, for example, Patent Document 1 and Patent Document 2). Further, in order to light a high-intensity discharge lamp, a lighting device is required unlike a conventional halogen bulb, and downsizing of the lighting device is required with the spread to small cars.

  An example of a discharge lamp lighting device for lighting a high-intensity discharge lamp (hereinafter simply referred to as a discharge lamp) is shown in FIG. This conventional apparatus converts the DC power of a battery (DC power supply) 1 mounted in an automobile into rectangular wave power alternating at a low frequency and supplies it to a discharge lamp, and applies and discharges a high voltage pulse voltage. And an igniter section 4 for starting the electric lamp 2. The inverter unit 3 includes a power adjustment circuit 10 that adjusts the power supplied from the DC power supply 1 to the discharge lamp 2, and a DC / rectangular that converts the power adjusted by the power adjustment circuit 10 into a low-frequency rectangular wave voltage / current. A wave conversion circuit 11, a filter circuit 12 provided on the output side of the DC / rectangular wave conversion circuit, a power adjustment circuit 10, and a control circuit unit 13 that controls the DC / rectangular wave conversion circuit 11 are provided. The power adjustment circuit 10 is a conventionally known flyback type DC / DC converter, and the control circuit unit 13 switches the switching element Q1 at several tens of kHz to several hundreds of kHz and performs PWM control to perform power adjustment. Is called. The DC / rectangular wave conversion circuit 11 includes a bridge circuit in which a series circuit of two switching elements Q2 and Q3 and a series circuit of two switching elements Q4 and Q5 are connected in parallel to each other, and is positioned on a diagonal side by the control circuit unit 13. By alternately switching the period during which the two switching elements Q2 and Q5 are turned on and the period during which the two switching elements Q3 and Q4 are turned on at a cycle of several hundreds of Hz, Outputs square wave voltage / current. The filter circuit 12 includes two common mode chokes 12a and 12a and two capacitors connected in series between the power supply path from the DC / rectangular wave conversion circuit 11 to the discharge lamp 2 between the common mode chokes 12a and 12a. C1 and C2, and the connection point of the two capacitors C1 and C2 is grounded.

  The igniter section 4 outputs a voltage doubler rectifier circuit comprising a pair of capacitors and diodes, a pulse transformer PT having a primary side connected to the voltage doubler rectifier circuit and a secondary side connected to the discharge lamp 2, and a voltage doubler rectifier circuit. It has a conventionally known configuration including a switching element (thyristor) for applying a high voltage to the primary side of the pulse transformer PT, and applies a high voltage pulse voltage generated on the secondary side of the pulse transformer PT to release it. The electric light 2 is started.

As shown in FIG. 11, in the conventional discharge lamp lighting device configured as described above, the inverter unit 3 is housed in a casing 100 made of, for example, aluminum die casting, and the igniter unit 4 is housed in a housing 101 made of an insulating material. The inverter unit 3 and the igniter unit 4 are connected by a cable 102 and the igniter unit 4 is connected by a cable 104 to a socket 103 in which a discharge lamp (HID bulb) 2 is detachably mounted. The casing 100 in which the inverter unit 3 is housed is fixed to the outer surface of the bottomed cylindrical lamp body 105 whose front surface is open, and the housing 101 in which the igniter section 4 is housed is fixed inside the lamp body 105. The In addition, a socket 103 is attached to a bowl-shaped reflecting mirror 106 opened forward, and the reflecting mirror 106 is housed and fixed inside the lamp body 105.
JP 2002-109918 A JP 2001-6889 A

  By the way, in the above-described conventional device, high-frequency switching noise is generated from the switching elements Q1 to Q5 of the power adjustment circuit 10 and the DC / rectangular wave conversion circuit 11, and high-frequency noise is also generated from the discharge lamp 2 due to polarity reversal. Here, the frequency of the switching noise belongs to a medium wave band (300 kHz to 3 MHz) mainly used for AM radio broadcasting, whereas the frequency of high-frequency noise emitted from the discharge lamp 2 is mainly used for FM radio broadcasting. Therefore, two types of filters are necessary because they belong to the very high frequency (VHF) band (30 MHz to 300 MHz) and have different frequency bands. For this reason, for example, in the conventional device described in Patent Document 2, the switching noise in the medium wave band is suppressed by the filter circuit 12 of the inverter unit 3, and at the same time, the inductor Lf1 is connected to the output side of the igniter unit 4 as shown in FIG. , Lf2 and a capacitor Cf are provided to suppress high-frequency noise generated in the discharge lamp 2. However, the provision of the filter circuit 5 causes a problem that the igniter section 4 is enlarged.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a discharge lamp lighting device capable of suppressing noise in different frequency bands while avoiding an increase in size of the device and a complicated circuit configuration. is there.

  In order to achieve the above object, the first aspect of the invention provides an inverter unit for converting DC power of a DC power source into rectangular wave power alternating at a low frequency and supplying the same to a discharge lamp, and applying and releasing a high voltage pulse voltage. The inverter unit includes a power adjustment circuit that adjusts the power supplied from the DC power source to the discharge lamp, and the power adjusted by the power adjustment circuit is converted into a low-frequency rectangular wave voltage / current. A DC / rectangular wave conversion circuit for conversion, and a filter circuit provided on the output side of the DC / rectangular wave conversion circuit, the filter circuit being provided between the power supply path from the DC / rectangular wave conversion circuit to the discharge lamp. It is characterized by comprising an even number of capacitors connected in series and an impedance element connected between the midpoint of the series circuit of the even number of capacitors and the ground.

  According to the present invention, the noise component of the relatively low frequency band generated in the inverter unit flows to the ground via the capacitor and the impedance element, and therefore does not leak out of the inverter unit, and is relatively high generated in the discharge lamp. Since the noise component in the frequency band returns to the discharge lamp through the capacitor, it can be prevented from leaking to the inverter unit. In addition, since it is only necessary to add an impedance element to the conventional example, it is not necessary to provide a filter for suppressing the noise component generated in the discharge lamp on the output side of the igniter, and the size of the device and the circuit configuration are increased. Thus, noise in different frequency bands can be suppressed while avoiding complexity.

  According to a second aspect of the present invention, there is provided a socket according to the first aspect of the present invention, further comprising a socket connected to the output side of the DC / rectangular wave conversion circuit via the filter circuit and to which the discharge lamp is detachably mounted. The parts are integrally formed.

  According to the present invention, a cable for connecting the igniter portion and the socket is not required, and the entire apparatus can be reduced in size.

  According to the present invention, the noise component of the relatively low frequency band generated in the inverter unit flows to the ground via the capacitor and the impedance element, and therefore does not leak out of the inverter unit, and is relatively high generated in the discharge lamp. Since the noise component in the frequency band returns to the discharge lamp through the capacitor, it can be suppressed from leaking to the inverter unit, and only the impedance element is added to the conventional example, so the igniter unit There is no need to provide a filter for suppressing the noise component generated in the discharge lamp on the output side of the lamp, and there is an effect that noise in different frequency bands can be suppressed while avoiding enlargement of the apparatus and complication of the circuit configuration.

(Embodiment 1)
The discharge lamp lighting device of this embodiment is for lighting a high-intensity discharge lamp (HID bulb) used for a vehicle headlamp, and has the circuit configuration shown in FIG. However, since the basic circuit configuration of this embodiment is the same as that of the conventional example shown in FIG. 10, the same reference numerals are given to the common components and the description thereof is omitted.

  The present embodiment is different from the conventional example in the configuration of the filter circuit 12. That is, the filter circuit 12 of the present embodiment includes a midpoint of a series circuit of an even number (two) of capacitors C1 and C2 connected in series between the feeding paths from the DC / rectangular wave conversion circuit 11 to the discharge lamp 2. An impedance element Z is connected between the grounds. Here, the impedance element Z may be a resistor R1 as shown in FIG. 2A or an inductor L1 as shown in FIG. Further, the component form of the impedance element Z may be either a lead component or a surface mount component.

  Thus, since a noise component in a relatively low frequency band (for example, a medium wave band of AM radio broadcasting) generated in the inverter unit 3 flows to the ground via the capacitors C1 and C2 and the impedance element Z, the inverter unit 3 Since the noise component of the relatively high frequency band (for example, the ultra-short wave band of FM radio broadcasting) generated in the discharge lamp 2 returns to the discharge lamp 2 through the capacitors C1 and C2, the leakage of the inverter unit 3 Can be prevented from leaking. In addition, since it is only necessary to add the impedance element Z to the conventional example, it is not necessary to provide the filter 5 for suppressing the noise component generated in the discharge lamp 2 on the output side of the igniter unit 12, and the size of the apparatus is large. It is possible to suppress noise in different frequency bands while avoiding simplification and complicated circuit configuration.

  However, in order to achieve the above-described action, the impedance of the impedance element Z needs to be smaller than the combined impedance of the capacitors C1 and C2 in the low frequency band and larger in the high frequency band. That is, when the combined impedance of the capacitors C1 and C2 is fixed and the resistance value R1 of the resistor R1 that is the impedance element Z is changed, the electric field strength (dBμV / m) of noise leaking from the filter circuit 12 in each frequency band is examined. As shown in FIG. 3, in the low frequency band (about 500 kHz to 1600 kHz), the electric field strength of noise is higher when the resistance value R1 is smaller (R1 = 0Ω) than when the resistance value R1 is large (R1 = 56Ω). As shown in FIG. 4, in the high frequency band (about 76 MHz to 90 MHz), the electric field of noise is higher when the resistance value R1 is larger (R1 = 56Ω) than when the resistance value R1 is small (R1 = 11Ω). It became clear that the strength was decreasing. Therefore, in order to reduce noise in two different frequency bands, it is necessary to set the impedance (resistance value R1) of the impedance element Z to an appropriate value (for example, about 20 to 60Ω). If the inductor L1 is used as the impedance element Z as shown in FIG. 2B, the impedance in the low frequency band (AM band) is small and the high frequency band (FM band) as shown in FIG. In this case, it is sufficient to select the inductor having a large impedance, and the selection of the inductor L1 can be widened.

(Embodiment 2)
In the present embodiment, as shown in FIG. 6, the discharge lamp 2 is detachably mounted while being connected to the output side of the DC / rectangular wave conversion circuit 11 through a filter circuit 12 using a resistance value R1 as an impedance element Z. The socket 6 is provided, and the socket 6 and the igniter section 4 are integrally formed.

  The inverter unit 3 includes an output of the power adjustment circuit 10 in addition to the power adjustment circuit 10, the DC / rectangular wave conversion circuit 11, the filter circuit 12, and the control circuit unit 13, which are flyback type DC / DC converters as in the conventional example. Are boosted and supplied to the igniter unit 4 and a control power source 15 for stabilizing the DC output of the DC power source 1 and supplying operation power for the control circuit unit 13. Further, the igniter section 4 is different in that the discharge gap SG is connected to the primary side of the pulse transformer PT instead of the thyristor, and the pulse transformer PT is discharged when the discharge gap SG is discharged by the voltage boosted by the booster circuit 14. A high voltage pulse voltage of 10 to 30 kV is generated on the secondary side. A terminal (described later) of the socket 6 is connected to the secondary side of the pulse transformer PT, and rectangular wave power is supplied to the discharge lamp (HID bulb) 2 through the socket 6.

  As shown in FIGS. 7 to 9, the socket 6 in the present embodiment is a thermoplastic synthetic resin such as a polyetherimide resin, as a wiring circuit board (not shown) made of a metal plate formed using a lead frame. The base 20 which is a molded product is formed simultaneously by insert molding. A connection piece 31 is provided at an appropriate location of the wiring circuit board to mount an electronic component constituting the igniter unit 4, and the connection piece 31 protrudes from the surface of the base 20.

  The pulse transformer PT described above is embedded in the base 20 as shown in FIG. That is, of the electronic components mounted on the wiring circuit board, the pulse transformer PT is mounted on the wiring circuit board by welding before the base 20 is formed, and is embedded in the base 20 by forming the base 20. At this time, a terminal piece (not shown) of the pulse transformer PT for connecting the primary winding and the secondary winding to the external circuit is exposed to the outside from the surface of the base 20.

  As shown in FIG. 9, the base 20 is integrally provided with a socket port 21 to which the discharge lamp 2 is connected on one surface in the thickness direction of the substrate portion 22, and the connection pieces 31 described above protrude from both surfaces in the thickness direction of the substrate portion 22. The connection piece 31 is formed so that an electronic component can be mounted. Hereinafter, the surface on which the socket opening 21 is provided in the thickness direction of the substrate portion 22 is referred to as the front surface. That is, the pulse transformer PT is disposed on the rear surface side of the substrate unit 22. The socket port 21 is formed in a double cylindrical shape composed of an inner cylinder 21a and an outer cylinder 21b in accordance with the shape of the suitable discharge lamp 2, and an inner electrode 51 is disposed along the inner surface of the inner cylinder 21a. The outer cylinder 21b is formed with an electrode holding groove 21c that is partially opened to the outer surface of the outer cylinder 21b and opened to the front end surface of the outer cylinder 21b. A base portion of the outer electrode 52 formed of a metal plate is inserted into the electrode holding groove 21c. The outer electrode 52 includes a contact spring 52a that elastically contacts a base (not shown) of the discharge lamp 2, a holding piece (not shown) that is inserted into the electrode holding groove 21c, and an outside of the outer cylinder 21b in the electrode holding groove 21c. An electrode terminal piece 52c projecting outward from the outer cylinder 21b from a portion opened to the side surface is integrally provided. The electrode terminal piece 52 c is joined to the connection piece 31 provided on the wiring circuit board and protruding from the base 20.

  The board portion 22 of the base 20 has a shape in which one side of a rectangle is formed in an arc shape when viewed from the front, and the socket port 21 described above is provided in the vicinity of the arcuate one side on the front surface of the board portion 22. ing. Further, the pulse transformer PT is arranged so that one side in the longitudinal direction is along one side adjacent to the one side of the arc shape of the substrate portion 22. The thickness of the portion of the substrate portion 22 where the pulse transformer PT is not provided is smaller than the portion of the substrate portion 22 where the pulse transformer PT is provided, and further, the portion of the substrate portion 22 where the pulse transformer PT is not provided and overlaps the socket port 21. A step portion 23 that is stepped backward from the front surface is formed in the portion that is not. A capacitor C4 constituting the igniter unit 4 is placed on the step unit 23. A discharge gap SG and a capacitor C3 are disposed on the rear surface side of the substrate portion 22 corresponding to the step portion 23. These electronic components are joined to the connection piece 31 by resistance welding or the like.

  On one side of the arc shape of the base plate portion 22 of the base 20, an enclosing wall 24 that protrudes from the rear surface of the base plate portion 22 is formed continuously and integrally with the portion where the pulse transformer PT is embedded, and further corresponds to the step portion 23. An assembly piece 25 protruding in the front-rear direction is formed integrally on the side surface of the substrate portion 22. An appropriate number of assembly claws 26 project from the outer surfaces of the surrounding wall 24 and the assembly piece 25.

  The base 20 on which electronic components are mounted and the socket port 21 is integrally formed as described above is housed in a case 60 as shown in FIG. The case 60 is formed by a rear case 61 in which the base 20 is accommodated and the front side of the substrate portion 22 is opened, and a front case 62 that is covered on the front surface of the rear case 61. The rear case 61 and the front case 62 are coupled by ultrasonic welding, are coupled using a fixing tool such as a screw or a crimping hook, or are coupled by uneven engagement.

  The rear case 61 is made of a conductive material. Also, an assembly hole (not shown) is formed in the peripheral wall of the rear case 61 to engage with an assembly claw 26 protruding from the peripheral surface of the base 20. When the base 20 is attached to the rear case 61, the assembly claw 26 is assembled. By engaging with the hole, the base 20 is coupled to the rear case 61. The front case 62 is integrally provided with a cylindrical socket tube 63 for mechanically holding the discharge lamp 2 connected to the socket port 21. The socket cylinder 63 has a plurality of coupling grooves 64 opened on the front surface and the inner side surface of the socket cylinder 63 in order to couple the discharge lamp 2 by the bayonet method. Each coupling groove 64 is formed in an L shape having a portion extending rearward from the front end of the socket tube 63 and a portion extending in the circumferential direction of the socket tube 63, and protrudes from the base of the discharge lamp 2. When the connected connecting pin is inserted into the connecting groove 64 and the discharge lamp 2 is rotated, the connecting pin is introduced into the back of the connecting groove 64 and the discharge lamp 2 is held by the socket tube 63. Since this type of bayonet coupling is a well-known technique, a description thereof will be omitted.

  In order to connect the igniter unit 4 mounted on the base 20 to the inverter unit 3, an input line Lx is introduced into the case 60. The input line Lx is introduced into the case 60 through a notch (not shown) provided in the front case 62, and a guide cylinder 65 projects outwardly around the notch in the front case 62. A tension stopper member 66 formed of a band is wound around the guide cylinder 65 so that the tension acting on the input line Lx does not reach the connection portion with the igniter section 4 housed in the case 60.

  As described above, in this embodiment, since the socket 6 and the igniter section 4 are integrally formed, a cable for connecting the igniter section 4 and the socket 6 is not required, and the entire apparatus can be reduced in size.

1 is a circuit diagram of Embodiment 1. FIG. (A) (b) is a circuit diagram of the filter circuit in the same as the above. It is a wave form diagram which shows the relationship between the impedance value of the impedance element in the same as the above, and the noise of a low frequency band. It is a wave form diagram which shows the relationship between the impedance value of an impedance element in the same as the above, and the noise of a high frequency band. It is explanatory drawing explaining the frequency characteristic of the inductor used as an impedance element same as the above. FIG. 6 is a circuit diagram of a second embodiment. It is a perspective view which shows the external appearance of the socket in the same as the above. It is a rear surface side perspective view which shows the base used for the same as the above. It is a perspective view of the front side which shows the base used for the same as the above. It is a circuit diagram which shows a prior art example. It is sectional drawing which shows the headlamp of the motor vehicle using the same as the above. It is a circuit diagram of the principal part same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Discharge lamp 3 Inverter part 4 Igniter part 12 Filter circuit C1, C2 Capacitor Z Impedance element

Claims (2)

  It has an inverter unit that converts the DC power of the DC power source into rectangular wave power that alternates at a low frequency and supplies it to the discharge lamp, and an igniter unit that starts the discharge lamp by applying a high-voltage pulse voltage. A power adjustment circuit that adjusts the power supplied from the power source to the discharge lamp, a DC / rectangular wave conversion circuit that converts the power adjusted by the power adjustment circuit into a low-frequency rectangular wave voltage / current, and a DC / rectangular wave conversion A filter circuit provided on the output side of the circuit, the filter circuit including an even number of capacitors connected in series between the power supply paths from the DC / rectangular wave conversion circuit to the discharge lamp, and an even number of capacitors. A discharge lamp lighting device comprising an impedance element connected between a midpoint of a series circuit and a ground.   A socket connected to the output side of the DC / rectangular wave conversion circuit through a filter circuit and to which a discharge lamp is detachably mounted is provided, and the socket and the igniter section are integrally formed. The discharge lamp lighting device according to 1.

Images