JP2009170804A - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and thin-shaped lighting device capable of suppressing a cost increase. <P>SOLUTION: A transformer used for the lighting device includes a nearly rectangular substrate 7 composed of double face print circuit board and a core part 8 composed of a pair of ferrite cores 8a, 8b attached to the substrate 7. A secondary coil n2 is coil-formed on an upper surface of the substrate 7 by pattern wiring, and a tertiary coil n3 is coil-formed on a lower surface of the substrate 7 by pattern wiring. A pair of land patterns 7c, 7c is formed on an upper surface of the substrate 7, and primary coils n11, n12 are respectively mounted so as to overlap the secondary coil n2 in a thickness direction of the substrate 7 by soldering both ends of the primary coils n11, n12 to respective corresponding land patterns 7c. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting device.

  Conventionally, a transformer using a printed coil in which a coil is patterned on a resin substrate has been provided (for example, see Patent Document 1). This transformer is configured by laminating a plurality of printed coils, and the adjacent printed coils are secured by heat-resistant tape.

There is also provided a transformer in which the printed coil and an edgewise coil using a rectangular wire are used in combination (for example, see Patent Document 2). This transformer is configured by sandwiching a print coil and an edgewise coil incorporated in a bobbin from both sides by a set of two cores.
JP-A-9-326315 (paragraph [0007] -paragraph [0009] and FIG. 1) JP 11-345721 A (paragraph [0014] -paragraph [0019] and FIG. 1)

  In general, electrical components such as an in-vehicle HID lighting device and an LED driver are generally arranged on the bottom surface or the back surface of an in-vehicle lamp, and a reduction in thickness is desired. Here, in order to reduce the thickness of the lighting device, it is effective to reduce the thickness of the transformer having the largest thickness among the devices, and the transformer shown in the above-mentioned Patent Document 1 uses a printed coil. However, when multiple output lines are required, such as in-vehicle HID lighting devices and LED drivers, it is necessary to increase the number of printed coils to increase the number of windings, which is expensive. It was necessary to use a plurality of print coils, which increased the cost.

  Further, in the transformer shown in the latter patent document 2, when a plurality of output lines are required like in-vehicle HID lighting devices and LED drivers, it is necessary to arrange a plurality of windings side by side with respect to the bobbin. In addition, since it is necessary to ensure insulation between adjacent windings, the thickness can be reduced, but the mounting area increases, resulting in an increase in cost.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a small and thin lighting device that suppresses cost increase.

  The invention of claim 1 includes a transformer for converting an input voltage into a predetermined voltage, and a lighting circuit including the transformer, and the transformer has a core part that forms a magnetic circuit and a winding part that forms an electric circuit. The winding portion includes at least one first coil that is directly mounted on the printed wiring board so as to overlap the first coil made of pattern wiring formed on the printed wiring board and the first coil in the thickness direction of the printed wiring board. And 2 coils.

  The invention of claim 2 is characterized in that the second coil is formed of a rectangular wire.

  The invention of claim 3 is characterized in that the second coil is formed of a self-bonding electric wire, and the self-bonding electric wire formed in a coil shape in advance is mounted on a printed wiring board.

  According to a fourth aspect of the present invention, in the printed wiring board, an interval holding member for providing an interval is provided between the second coil and the portion opposite to the portion where the joint portion of the second coil is joined. It is characterized by that.

  The invention of claim 5 is characterized in that the transformer includes a plurality of output windings composed of at least one of the first and second coils.

  The invention of claim 6 is characterized in that at least the transformer is filled with a filler.

  According to the first aspect of the present invention, since the winding portion is constituted by the first coil patterned on the printed wiring board and the second coil directly mounted on the printed wiring board, the transformer is thin. In addition, there is an effect that the cost can be reduced as compared with the case where only the printed coil is used as in the conventional example or the case where the bobbin which fixes the coil is used.

  According to the invention of claim 2, by using a flat wire as the second coil, the coil height can be reduced as compared with the case of using a round wire, so that the transformer can be further thinned. There is an effect that can be done.

  According to the invention of claim 3, since the coil can be formed without using the bobbin by using the self-bonding electric wire as the second coil, the cost increase is suppressed as compared with the case where the bobbin is used. There is an effect that can be.

  According to the invention of claim 4, in the printed wiring board, the gap holding member for opening a gap between the second coil and the portion opposite to the portion where the joint portion of the second coil is joined. By providing the second coil, the second coil can be inclined with respect to the substrate surface when mounted on the printed wiring board, so that the bonding area between the bonding portion of the second coil and the substrate is increased, and soldering is more reliably performed. In addition, there is an effect that it is possible to ensure an insulation distance from the first coil by providing a gap between the first coil and the first coil by the gap holding member.

  According to the invention of claim 5, since the transformer includes a plurality of output windings, there is an effect that it is possible to provide a lighting device that can be used for an HID lamp lighting device or an LED driver.

  According to the invention of claim 6, since the second coil can be prevented from moving due to vibration or the like by filling the transformer with the filler, contact failure between the printed wiring board and the second coil can be prevented. Therefore, there is an effect that it is possible to provide a highly reliable lighting device.

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 and 2. The lighting device A of the present embodiment is used for lighting a HID lamp (High intensity discharge lamp) as a light source of an in-vehicle headlamp, for example.

  As shown in FIG. 2, the lighting device A is connected to a DC power source E such as an in-vehicle battery via the input filter unit 1 and the input filter unit 1, and an input voltage supplied from the DC power source E is a high voltage, for example. A DC / DC converter unit 2 that boosts the lamp B1 composed of a mercury lamp to a lamp voltage suitable for stable lighting, and an inverter unit 3 that converts a DC voltage output from the DC / DC converter unit 2 into a rectangular wave AC voltage; The output filter unit 4, the igniter unit 5 that generates a high voltage pulse for starting the valve B 1, and the control unit 6 that controls the DC / DC converter unit 2 and the inverter unit 3. The power required for stable lighting is supplied.

  The input filter unit 1 includes a capacitor C1 connected in parallel to the DC power supply E, an inductor L1 connected in series to the DC power supply E, and an electrolytic capacitor C2 connected in parallel to the DC power supply E via the inductor L1. The input end of the DC / DC converter unit 2 is connected between both ends of the electrolytic capacitor C2.

  The DC / DC converter unit 2 includes a step-up transformer Tr1 and a switching element Q1 composed of a MOSFET connected between output terminals of the input filter unit 1 via two primary windings n11 and n12 connected in parallel to the step-up transformer Tr1. Etc. The step-up transformer Tr1 includes a secondary winding n2 and a tertiary winding n3, and a series circuit of a diode D1 and a smoothing capacitor C3 is connected between both ends of the secondary winding n2. The diode D1 is connected to a polarity that prevents a charging current from the step-up transformer Tr1 to the capacitor C3 when the switching element Q1 is turned on. That is, electromagnetic energy is accumulated in the step-up transformer Tr1 when the switching element Q1 is turned on, this electromagnetic energy is released from the step-up transformer Tr1 when the switching element Q1 is turned off, and a charging current is passed through the capacitor C3 via the diode D1. Therefore, the connection point between the capacitor C3 and the secondary winding n2 is on the low potential side of the capacitor C3. In the configuration shown in FIG. 2, the high potential side of the capacitor C3 is connected to the circuit ground to be a reference potential. That is, the negative electrode of the DC power supply E and the high potential side of the output of the DC / DC converter unit 2 have the same voltage, and the output voltage of the DC / DC converter unit 2 is negative with respect to the reference voltage. Here, on / off of the switching element Q1 is controlled by the control unit 6 in terms of duty and frequency, and the output voltage of the DC / DC converter unit 2 is controlled. The output voltage of the DC / DC converter unit 2 is input to the inverter unit 3. A transformer is constituted by the step-up transformer Tr1.

  The inverter unit 3 includes four switching elements Q2 to Q5 made of MOSFETs, and is bridge-connected in such a manner that two arms each consisting of a series circuit of two switching elements Q2, Q3 and Q4, Q5 are connected in parallel. The connection points of the switching elements Q2 and Q3 and the connection points of Q4 and Q5 in each arm are the output ends. Here, the on / off frequency of the switching elements Q2 to Q5 is controlled by the control unit 6. When the switching elements Q2 and Q5 are on, the switching elements Q3 and Q4 are off, and when the switching elements Q3 and Q4 are on. The switching elements Q2 and Q5 are controlled to be turned off. The switching elements Q2 to Q5 are turned on / off at a relatively low frequency, and a rectangular wave alternating voltage is applied to the valve B1 via the secondary winding of the pulse transformer Tr2 of the igniter unit 5. Before the bulb B1 is turned on, the control unit 6 controls the switching elements Q3 and Q4 to turn on and the switching elements Q2 and Q5 to turn off, and the connection point of the switching elements Q4 and Q5 is the switching elements Q2, Q3. The negative electrode side of the connection point.

  The control unit 6 includes a power supply voltage monitoring unit 6b that detects an input voltage supplied from the DC power supply E based on a potential at a connection point between the capacitor C1 of the input filter unit 1 and the inductor L1, and a capacitor C3 of the DC / DC converter unit 2. And a ramp voltage detection unit 6e for detecting the output voltage of the DC / DC converter unit 2, that is, the lamp voltage of the bulb B1, by the potential at the connection point between the second winding n2 of the step-up transformer Tr1 and the other end and the subsequent stage of the capacitor C3. A lamp current detector 6f for detecting the output current of the DC / DC converter unit 2, that is, the lamp current of the bulb B1, by the voltage across the resistor R1 for current detection inserted between the lamp and the circuit, and the lamp voltage detector 6e, Based on the detection value of the lamp current detector 6f, the on / off frequency and duty of the switching element Q1 of the DC / DC converter 2 are determined. An arithmetic unit 6a that controls the moving circuit 6c and generates a signal for controlling the on / off frequency of the switching elements Q2 to Q5 of the inverter unit 3 via the driving circuit 6d according to the lighting state of the bulb B1. The drive circuits 6c and 6d are provided.

  Here, in the DC / DC converter unit 2, a series circuit of a capacitor C4 and two resistors R2 and R3 is connected in parallel to a series circuit of a capacitor C3 and a resistor R1, and a diode D2 is connected in parallel to the resistor R2. A starting auxiliary circuit configured as described above is provided. This auxiliary start circuit supplies the valve B1 with a current to the valve B1 together with the DC / DC converter unit 2 at the time of starting the valve B1, thereby quickly lighting the valve B1, and the capacitor C4 is connected to the resistors R1, R2, The charge path of the capacitor C4 is charged through R3, and the discharge path of the capacitor C4 is a path through the diode D2 and the resistor R3.

  The tertiary winding n3 of the step-up transformer Tr1 provided in the DC / DC converter unit 2 constitutes a step-up circuit together with the diode D3, the capacitor C5, and the resistors R4 and R5, and the step-up transformer Tr1 when the switching element Q1 is turned off. To the capacitor C5 through the diode D3.

  The output filter unit 4 includes a capacitor C6 connected between the output ends of the inverter unit 3, an inductor L2, a capacitor C7, and a series circuit including two capacitors C8 and C9. The capacitor C8 and the capacitor C9 Is connected to the circuit ground. Here, the output filter unit 4 can reduce high-frequency noise generated from the bulb B1 when the polarity of the lamp current of the bulb B1 is reversed.

  The igniter unit 5 includes a capacitor C10 connected between output terminals of the output filter unit 4, a capacitor C11 connected to the capacitor C5 via the resistors R4 and R5 and the output filter unit 4, and a secondary winding of the valve B1. And a series circuit of a secondary winding and a series circuit of a valve B1 connected between both ends of the capacitor C10 and a primary circuit of the pulse transformer Tr2 is connected between both ends of the capacitor C11. It is comprised with the spark gap SG connected. With this configuration, a voltage determined by the output voltage of the DC / DC converter unit 2 and the output voltage of the above-described booster circuit is applied to the capacitor C11, and when the voltage across the capacitor C11 reaches the breakdown voltage of the spark gap SG, The gap SG is conducted, and the capacitor C11 is discharged through the primary winding of the pulse transformer Tr2. As a result, a high pulse voltage obtained by boosting the voltage applied to the primary winding is induced in the secondary winding of the pulse transformer Tr2, and the discharge of the valve B1 is started by this high voltage pulse. Here, the capacitor C <b> 10 has a low impedance with respect to the pulse voltage, and prevents the pulse voltage from being applied to the inverter unit 3.

  Next, a transformer used in the lighting device A will be described with reference to FIG. The transformer includes a board 7 (printed wiring board) made of a double-sided printed board and a core portion 8 made of a pair of ferrite cores 8a and 8b attached to the board 7. In addition, about each part which comprises the lighting device A mentioned above, you may comprise so that it may mount in the board | substrate 7, and you may comprise so that it may mount in the board | substrate different from the board | substrate 7. FIG.

  As shown in FIGS. 1A and 1B, the substrate 7 is formed in a horizontally long substantially rectangular plate shape, and has a vertically long rectangular insertion hole 7a on both ends in the longitudinal direction (left and right direction in FIG. 1A). 7a, and a vertically long elliptical insertion hole 7b is provided between the insertion holes 7a and 7a. Also, a pair of land patterns 7c and 7c printed with solder paste for soldering the primary windings n11 and n12 to the substrate 7 near one insertion hole 7a (right side in FIG. 1A). Is formed.

  Further, as shown in FIG. 1B, the substrate 7 has the above-described secondary winding n2 coiled by pattern wiring on the top surface, and the above-described tertiary winding n3 coiled by pattern wiring on the bottom surface of the substrate 7. Is formed. Further, primary windings n11 and n12 are mounted on the upper surface of the substrate 7 so as to overlap the secondary winding n2 in the thickness direction of the substrate 7 (vertical direction in FIG. 1B).

  The primary windings n11 and n12 are each composed of a rectangular wire having a substantially rectangular cross-sectional shape, and each primary winding n11 and n12 is preliminarily edgewise-wound (a method of winding a coil along the thickness direction of the rectangular wire, That is, it is formed in a coil shape by vertical winding). Then, with the primary windings n11 and n12 arranged at predetermined positions on the substrate 7, the solder of the land pattern 7c is melted by applying heat to the end portions of the primary windings n11 and n12, respectively. 7c (reflow method). Insulation between the primary windings n11 and n12 and the secondary winding n2 patterned on the substrate 7 is ensured by covering the primary windings n11 and n12. Here, the first coil is constituted by the secondary winding n2 and the tertiary winding n3 patterned on the substrate 7, and the second coil is constituted by the primary windings n11 and n12 made of rectangular wires, Further, the first coil and the second coil constitute a winding part. When the primary windings n11 and n12 are mounted on the substrate 7, the coverings of both ends of the primary windings n11 and n12 (that is, mounting portions on the substrate 7) are peeled off, and the portions where the conductors are exposed are exposed. It is desirable to apply pre-solder so that the soldering by the reflow method can be easily performed.

  As shown in FIG. 1B, the core portion 8 is configured by combining an E type ferrite core 8a and an I type ferrite core 8b, and corresponds to each end piece 8c at both longitudinal ends of the ferrite core 8a. When the center piece 8d is inserted into the insertion hole 7b from the upper surface side and the ferrite core 8b is assembled to the ferrite core 8a from the lower surface side, the primary windings n11, n12, secondary winding The core portion 8 is attached to the substrate 7 so as to sandwich the n2 and the tertiary winding n3. At this time, the space formed by the ferrite cores 8a and 8b may be filled with a filler. In this case, for example, the primary windings n11 and n12 mounted on the substrate 7 are moved by vibration or the like. Therefore, the contact failure between the board | substrate 7 and the primary windings n11 and n12 can be prevented, and the lighting device A with high reliability can be provided.

  Here, since the output power to the valve B1 is boosted to a predetermined ramp voltage via the primary windings n11 and n12 and the secondary winding n2 as described above, the primary windings n11 and n12 It is desirable that the power transmission efficiency between the secondary winding n2 is high. In the present embodiment, the primary windings n11, n12 and 2 are arranged in the thickness direction of the substrate 7 such that the primary windings n11, n12 overlap with the secondary winding n2 patterned on the substrate 7. The coupling coefficient with the next winding n2 is set high to increase the transmission efficiency. Further, as described above, the tertiary winding n3 constitutes a booster circuit that generates a high voltage pulse for starting the valve B1, and is connected to the primary windings n11 and n12 and the secondary winding n2. Although it is necessary to secure an insulation distance, in this embodiment, the tertiary winding n3 is arranged on the lower surface opposite to the upper surface of the substrate 7 on which the primary windings n11, n12 and the secondary winding n2 are arranged. As a result, a sufficient insulation distance is secured.

  Thus, in the transformer used in the lighting device A of the present embodiment, the first coil (secondary winding n2 and tertiary winding n3) patterned on the substrate 7 and the substrate 7 are directly mounted. Since the winding portion is composed of the second coil (primary windings n11 and n12), the transformer can be reduced in thickness and size as compared with the case where the transformer is composed only of the coil using the electric wire. Further, the cost increase can be suppressed as compared with the case where only the printed coil is used as in the conventional example or the case where the bobbin which fixes the coil is used. In addition, by using a rectangular wire as the primary windings n11 and n12, the coil height can be reduced as compared with the case of using a round wire, so that the transformer can be further reduced in thickness. Furthermore, for example, when the DC power source E is a 12V system, a current of about several tens of A flows through the primary windings n11 and n12. However, as in the present embodiment, the primary windings n11 and n12 By using a flat wire, the thickness can be increased compared to the case where the primary winding is formed by pattern wiring on the substrate (in this case, it is usually as thin as 35 μm or 70 μm), and the cost increase can be suppressed. it can. In addition, since the transformer of this embodiment includes the secondary winding n2 and the tertiary winding n3 as output windings, it is possible to provide a lighting device that can be used for an HID lamp lighting device or an LED driver.

  In the present embodiment, the case where the output coil is configured by the first coil (secondary winding n2 and tertiary winding n3) has been described as an example, but the first and second output windings are described as examples. Both of the coils may be used, or the output winding may be constituted by only the second coil. Also, the number of output windings is not limited to two, and may be appropriately designed according to the use application.

  Next, FIGS. 3A and 3B show another example of the present embodiment. The part of the substrate 7 opposite to the land pattern 7c with respect to the insertion hole 7b with respect to the transformer described in FIG. Is different in that a spacer 9 is provided. In addition, about another structure, it is the same as that of the transformer demonstrated in FIG. 1, The same code | symbol is attached | subjected to the same component and description is abbreviate | omitted.

  In the substrate 7 of the present example, a spacer 9 (one in this example) is provided at a portion opposite to the land pattern 7c with respect to the insertion hole 7b to be spaced from the primary windings n11 and n12. Is provided. The spacer 9 has an insulating property and has a height dimension of about 0.2 mm. Here, the spacer 9 constitutes a spacing member.

  Here, the assembly procedure of the transformer of this example will be described. First, the substrate 7 is placed in a state in which the surface on which the secondary winding n2 is patterned is directed upward (state shown in FIG. 3B), and the primary winding previously formed into a coil shape by edgewise winding. n11 and n12 are arranged at predetermined positions as shown in FIG. At this time, the primary windings n11 and n12 are arranged in a state of being inclined to the right side (that is, the side where the primary winding is soldered) with respect to the substrate surface by contacting the spacer 9. Thereafter, the solder of the land pattern 7c of the substrate 7 is melted by a reflow method, and the primary windings n11 and n12 are soldered to the substrate 7. Then, each end piece 8c of the ferrite core 8a is inserted into the corresponding insertion hole 7a of the substrate 7, the central piece 8d is inserted into the insertion hole 7b from the upper surface side, and the ferrite core 8b is assembled to the ferrite core 8a from the lower surface side. The core portion 8 is attached to the substrate 7 so as to sandwich the primary windings n11, n12, the secondary winding n2, and the tertiary winding n3, and the assembly of the transformer is completed.

  Thus, in the transformer used in the lighting device A of this example, the primary windings n11 and n12 can be inclined with respect to the substrate surface by bringing the primary windings n11 and n12 into contact with the spacer 9. Therefore, the bonding area between the end portions (bonding portions) of the primary windings n11 and n12 and the land pattern 7c of the substrate 7 is increased, and solder bonding can be performed more reliably. Further, even if the insulation distance between the primary windings n11 and n12 and the secondary winding n2 cannot be ensured only by the coating of the windings, the primary windings n11 and n12 and the secondary windings are separated by the spacer 9. By providing a predetermined interval between the line n2, the insulation distance between the primary windings n11, n12 and the secondary winding n2 can be secured.

  In this example, the case where one spacer 9 is used as the spacing member has been described as an example. However, the number of spacers is not limited to this example, and a plurality of spacers may be used. When a plurality of spacers are used, the heights of the spacers may be the same or different. Further, the spacing member is not limited to the spacer, and may be, for example, an insulating sheet. Moreover, what is necessary is just to design suitably also about the height dimension of a space | interval holding member.

  Further, in the present embodiment (the transformer shown in FIGS. 1 and 3), the case where the primary winding is a coil made of a rectangular wire and the secondary winding is a coil formed by patterning on the substrate has been described as an example. When the current flowing through the secondary winding is larger than the current flowing through the primary winding, the primary winding may be a coil formed by patterning the secondary winding, and the secondary winding may be a rectangular coil.

(Second Embodiment)
A second embodiment will be described with reference to FIG. In the first embodiment, the substrate 7 made of a double-sided printed board in which the secondary winding n2 and the tertiary winding n3 are patterned on both surfaces is used. However, in this embodiment, the primary windings N1 and 2 are used. A multilayer substrate 10 in which the next winding N2 is formed in four layers is used. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  The transformer used in the lighting device A of the present embodiment includes a multilayer board 10 in which three printed boards 11 are laminated as shown in FIGS. 4A and 4B, and is provided between the printed boards 11 and at both ends. A primary winding N1 and a secondary winding N2 are alternately formed by pattern wiring on the outer surface of the printed circuit board 11, and a coupling coefficient between the primary winding N1 and the secondary winding N2 is formed. Is increasing. In addition, longitudinally long rectangular insertion holes 10a and 10a for inserting both end pieces 8c and 8c of the ferrite core 8a are respectively penetrated on both ends of the multilayer substrate 10 in the longitudinal direction, and the insertion holes 10a and 10a are further inserted. A longitudinally long elliptical insertion hole 10b for passing through the central piece 8d of the ferrite core 8a is provided therebetween. Further, near one insertion hole 10a (on the right side in FIG. 4A), a pair of land patterns 10c and 10c printed with a solder paste for soldering the tertiary winding N3 to the multilayer substrate 10 are provided. Is formed.

  The tertiary winding N3 is formed of a self-bonding electric wire having a self-bonding layer formed so as to cover the conductor, and is formed in a planar coil in advance before being mounted on the multilayer substrate 10. Thus, by using a self-bonding electric wire as the tertiary winding N3, a coil can be formed without using a bobbin, so that an increase in cost can be suppressed as compared with the case where a bobbin is used. In FIG. 4 (a), the winding interval of the tertiary winding N3 is enlarged to simplify the illustration. However, in actuality, the self-bonding electric wires are wound tightly, and the self-bonding layers are formed. A planar coil is formed through the gap.

  Here, the assembly procedure of the transformer of this embodiment will be described. First, the multilayer substrate 10 is placed in a state where the surface on which the primary winding N1 is patterned is directed upward (state shown in FIG. 4B), and the tertiary winding N3 formed in advance on the planar coil is shown in FIG. As shown in 4 (a), it is arranged at a predetermined position. Thereafter, the solder printed on the land pattern 10c of the multilayer substrate 10 is melted by a reflow method, and the tertiary winding N3 is soldered to the multilayer substrate 10. Then, each end piece 8c of the ferrite core 8a is inserted into the corresponding insertion hole 10a of the multilayer substrate 10 and the central piece 8d is inserted into the insertion hole 10b from the upper surface side, and the ferrite core 8b is assembled to the ferrite core 8a from the lower surface side. The core portion 8 is attached to the multilayer substrate 10 so as to sandwich the primary winding N1, the secondary winding N2, and the tertiary winding N3, and the assembly of the transformer is completed. In addition, the insulation between the primary winding N1 and the tertiary winding N3 patterned on the multilayer substrate 10 is ensured by the self-bonding layer of the tertiary winding N3.

  Next, FIGS. 5A and 5B show another example of this embodiment. In the transformer described in FIGS. 4A and 4B, only the tertiary winding N3 is mounted on the multilayer substrate 10. FIG. However, in the transformer of this example, the tertiary winding N3 and the quaternary winding N4 are mounted on the multilayer substrate 10. In the following description, the same components as those in FIGS. 4A and 4B are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 5A, the multilayer substrate 10 of this example has a pair of land patterns 10c for mounting the tertiary winding N3 and the quaternary winding N4 on both ends in the longitudinal direction from the insertion holes 10a. 10c are formed. Further, the primary winding N1 patterned on the upper surface of the multilayer substrate 10 and the tertiary winding N3 and the quaternary winding N4 mounted on the multilayer substrate 10 are shown in FIG. 5B. Thus, the insulating film 12 is arranged, and the insulation distance between the primary winding N1, the tertiary winding N3, and the quaternary winding N4 is secured.

  Here, the assembly procedure of the transformer used in the lighting device A of this example will be described. First, the multilayer substrate 10 is arranged in a state in which the surface on which the primary winding N1 is patterned is directed upward (the state of FIG. 5B), and the tertiary windings N3 and 4 formed in advance on the planar coil. The next winding N4 is arranged opposite to a predetermined position as shown in FIG. Thereafter, the solder printed on the land pattern 10c of the multilayer substrate 10 is melted by the reflow method, and the tertiary winding N3 and the quaternary winding N4 are soldered to the multilayer substrate 10. Then, each end piece 8c of the ferrite core 8a is inserted into the corresponding insertion hole 10a of the multilayer substrate 10 and the central piece 8d is inserted into the insertion hole 10b from the upper surface side, and the ferrite core 8b is assembled to the ferrite core 8a from the lower surface side. The core portion 8 is attached to the multilayer substrate 10 with the primary winding N1, the secondary winding N2, the tertiary winding N3, and the quaternary winding N4 interposed therebetween, and the assembly of the transformer is completed.

  Thus, in the present embodiment (the transformer shown in FIGS. 4 and 5), the primary winding N1 and the secondary winding N2 (first coil) wired on the multilayer substrate 10 and the multilayer substrate 10 are arranged. Since the winding part is composed of the directly mounted tertiary winding N3 or quaternary winding N4 (second coil), the transformer is compared with the case where the transformer is composed only of coils using electric wires. The thickness and size of the substrate can be reduced, and the number of layers of the substrate can be reduced as compared with the case where the pattern wiring is formed only on the multilayer substrate, so that an increase in cost can be suppressed.

  In this embodiment, the case where the tertiary winding N3 and the quaternary winding N4 are mounted only on the upper surface of the multilayer substrate 10 has been described as an example. However, the arrangement of the tertiary winding N3 and the quaternary winding N4 is as follows. The present invention is not limited to this embodiment, and may be mounted on the lower surface of the multilayer substrate 10, or may be configured such that the tertiary winding N3 is mounted on one surface and the quaternary winding N4 is mounted on the other surface. May be.

  Moreover, as a 2nd coil, although the case where the flat wire was used in 1st Embodiment and the self-fusion wire was used in 2nd Embodiment was demonstrated to the example, in the 1st Embodiment, the self-fusion wire was used. May be used, or a rectangular wire may be used in the second embodiment.

The trans | transformer used for the lighting device of 1st Embodiment is shown, (a) is a perspective view, (b) is XX sectional drawing. It is a circuit diagram same as the above. The other example of the transformer used for the above is shown, (a) is a perspective view, (b) is an XX sectional view. The transformer used for the lighting device of 2nd Embodiment is shown, (a) is a perspective view, (b) is XX sectional drawing. The other example of the transformer used for the above is shown, (a) is a perspective view, (b) is an XX sectional view.

Explanation of symbols

7 PCB (printed wiring board)
8a Ferrite core (core part)
8b Ferrite core (core part)
A lighting device n11, n12 primary winding (second coil)
n2 secondary winding (first coil)
n3 tertiary winding (first coil)
Tr1 Step-up transformer (transformer)

Claims (6)

  A transformer for converting an input voltage into a predetermined voltage; and a lighting circuit including the transformer. The transformer includes a core part that forms a magnetic circuit and a winding part that forms an electric circuit. A first coil made of pattern wiring formed on the printed wiring board, and at least one second mounted directly on the printed wiring board so as to overlap the first coil in the thickness direction of the printed wiring board. A lighting device comprising a coil.   The lighting device according to claim 1, wherein the second coil is a rectangular wire.   2. The lighting device according to claim 1, wherein the second coil is formed of a self-bonding electric wire, and the self-bonding electric wire formed in a coil shape in advance is mounted on the printed wiring board.   In the printed wiring board, an interval holding member for providing an interval is provided between a portion opposite to a portion where the joint portion of the second coil is joined and the second coil. The lighting device according to any one of claims 1 to 3.   The lighting device according to claim 1, wherein the transformer includes a plurality of output windings including at least one of the first and second coils.   The lighting device according to claim 1, wherein at least the transformer is filled with a filler.

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