Light-emitting module, vehicle lighting device, and vehicle lamp

Abstract

The present invention provides a light-emitting module, a vehicle lighting device, and a vehicle lamp that can protect a light-emitting element against a negative surge, suppress a voltage drop, and achieve miniaturization. [Solution] The light-emitting module of the embodiment comprises at least one light-emitting element; a field-effect transistor electrically connected between the anode and cathode sides of the light-emitting element and a DC power supply; and a varistor connected in parallel with the field-effect transistor.

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a light-emitting module, a vehicle lighting device, and a vehicle lamp. [Background technology]

[0002] 2. Description of the Related Art From the viewpoint of energy saving and long life, light emitting modules including light emitting elements such as light emitting diodes are becoming increasingly popular instead of lamps having filaments.

[0003] Here, a light-emitting module may be subjected to a negative surge such as a reverse voltage or reverse pulse noise. If a negative surge is applied to a light-emitting element, the light-emitting element may break down. Therefore, to protect the light-emitting element from a negative surge, a diode is connected in series to the anode side of the light-emitting element.

[0004] In this case, if multiple light-emitting elements are connected in series to increase the luminous flux, a diode is connected in series to the multiple light-emitting elements connected in series, which increases the voltage drop, and there is a risk that the desired total luminous flux will not be obtained.

[0005] Therefore, a technique has been proposed for protecting light-emitting elements from negative surges using field-effect transistors, which can reduce voltage drops. However, a field effect transistor having a high breakdown voltage against a reverse voltage is large in size, and therefore, simply using a field effect transistor makes it difficult to reduce the size of a light emitting module.

[0006] Therefore, there has been a demand for the development of a technology that can protect light emitting elements against negative surges, suppress voltage drops, and achieve miniaturization. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-21883 Summary of the Invention [Problem to be solved by the invention]

[0008] The problem to be solved by the present invention is to provide a light-emitting module, a vehicle lighting device, and a vehicle lamp that can protect a light-emitting element against a negative surge, suppress voltage drops, and be compact. [Means for solving the problem]

[0009] The light-emitting module according to the embodiment comprises at least one light-emitting element; a field-effect transistor electrically connected between the anode and cathode sides of the light-emitting element and a DC power supply; and a varistor connected in parallel with the field-effect transistor. [Effects of the Invention]

[0010] According to the embodiments of the present invention, it is possible to provide a light-emitting module, a vehicle lighting device, and a vehicle lamp that can protect a light-emitting element against a negative surge, suppress a voltage drop, and achieve miniaturization. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic perspective view illustrating a vehicle lighting device according to an embodiment of the present invention; [Figure 2] 2 is a cross-sectional view of the vehicle lighting device taken along line AA in FIG. 1. [Figure 3] FIG. 10 is a circuit diagram illustrating a light-emitting circuit. [Figure 4] FIG. 2 is a schematic partial cross-sectional view illustrating a vehicle lamp. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, like components are designated by like reference numerals and detailed descriptions thereof will be omitted where appropriate.

[0013] (Light-emitting module and vehicle lighting device)

[0014] The light emitting module according to the present embodiment can be provided in, for example, a vehicle lighting device, etc. However, the use of the light emitting module is not limited to a vehicle lighting device. In the following, as an example, a case where the light-emitting module is provided in a vehicle lighting device will be described.

[0015] The vehicle lighting device 1 can be installed in, for example, automobiles, railroad cars, etc. Examples of the vehicle lighting device 1 installed in automobiles include those used as front combination lights (for example, an appropriate combination of daytime running lamps (DRLs), position lamps, turn signal lamps, etc.) and rear combination lights (for example, an appropriate combination of stop lamps, tail lamps, turn signal lamps, backup lamps, fog lamps, etc.). However, the uses of the vehicle lighting device 1 are not limited to these.

[0016] FIG. 1 is a schematic perspective view illustrating a vehicle lighting device 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the vehicle lighting device 1 taken along line AA in FIG. As shown in FIGS. 1 and 2, a vehicle lighting device 1 includes, for example, a socket 10, a light-emitting module 20, a power supply unit 30, and a heat transfer unit 40.

[0017] The socket 10 includes, for example, a mounting portion 11, a bayonet 12, a flange 13, heat dissipation fins 14, and a connector holder 15.

[0018] The mounting portion 11 is provided on the surface of the flange 13 opposite to the side on which the heat dissipation fins 14 are provided. The outer shape of the mounting portion 11 is, for example, cylindrical. The mounting portion 11 has, for example, a recess 11a that opens at the end opposite to the flange 13 side.

[0019] The bayonet 12 is provided, for example, on the side surface of the mounting portion 11. The bayonet 12 protrudes toward the outside of the vehicle lighting device 1. The bayonet 12 faces the flange 13. A plurality of bayonets 12 may be provided. The bayonet 12 is used when mounting the vehicle lighting device 1 to, for example, a housing 101 of a vehicle lamp 100 described below. The bayonet 12 can be used for a twist lock.

[0020] The flange 13 has, for example, a substantially circular plate shape. A side surface of the flange 13 is located outward of the side surface of the bayonet 12 from the vehicle lighting device 1.

[0021] The heat dissipation fin 14 is provided on the opposite side of the flange 13 from the mounting portion 11 side. At least one heat dissipation fin 14 can be provided. For example, as shown in FIG. 1, the socket 10 can be provided with multiple heat dissipation fins 14. The multiple heat dissipation fins 14 can be arranged side by side in a predetermined direction. The heat dissipation fin 14 has, for example, a plate or cylindrical shape.

[0022] The connector holder 15 is provided on the opposite side of the flange 13 from the mounting portion 11. The connector holder 15 can be provided alongside the heat dissipation fins 14. The connector holder 15 is cylindrical, and a connector 105 having a seal member 105a therein is inserted into the connector holder 15.

[0023] The socket 10 has the function of holding the light-emitting module 20 and the power supply unit 30, and the function of conducting heat generated in the light-emitting module 20 to the outside. Therefore, the socket 10 is preferably made of a material with high thermal conductivity. The socket 10 can be made of a metal such as an aluminum alloy, for example.

[0024] Furthermore, in recent years, there has been a demand for a lighter vehicle lighting device 1, and therefore a lighter socket 10. Therefore, the socket 10 can be formed from, for example, a highly thermally conductive resin. A highly thermally conductive resin is, for example, a resin such as PET (Polyethylene terephthalate) or nylon mixed with a filler using carbon, aluminum oxide, or the like. If the socket 10 contains a highly thermally conductive resin, it can efficiently dissipate heat generated in the light-emitting module 20. Furthermore, the weight of the socket 10 can be reduced.

[0025] The power supply unit 30 includes, for example, a plurality of power supply terminals 31 and a holding unit 32 . One end of each of the plurality of power supply terminals 31 protrudes from the bottom surface 11a1 of the recess 11a. One end of each of the plurality of power supply terminals 31 is soldered to the wiring pattern 21a provided on the substrate 21. The other end of each of the plurality of power supply terminals 31 is exposed inside the hole of the connector holder 15. The connector 105 is fitted into the plurality of power supply terminals 31 exposed inside the hole of the connector holder 15. The plurality of power supply terminals 31 are formed from a metal such as a copper alloy. Note that the number, shape, arrangement, material, etc. of the plurality of power supply terminals 31 are not limited to those exemplified and can be changed as appropriate.

[0026] When socket 10 is formed using, for example, a highly thermally conductive resin containing a carbon-based filler or a metal, socket 10 becomes conductive. Therefore, holding portion 32 is provided to insulate multiple power supply terminals 31 from conductive socket 10. Note that when socket 10 is formed using an insulating highly thermally conductive resin (for example, a highly thermally conductive resin containing an aluminum oxide-based filler), holding portion 32 can be omitted. For example, holding portion 32 can be press-fitted into a hole provided in socket 10 or adhered to the inner wall of the hole.

[0027] The heat transfer unit 40 is provided between the socket 10 and the light-emitting module 20 (substrate 21). As shown in FIG. 2, the heat transfer unit 40 is provided, for example, inside a recess 11b that opens to the bottom surface 11a1 of the recess 11a. For example, the heat transfer unit 40 can be adhered to the inner wall of the recess 11b, attached inside the recess 11b via heat-conducting grease (heat-dissipating grease), or embedded inside the recess 11b by insert molding. The heat transfer unit 40 can be made of a metal such as aluminum, an aluminum alloy, copper, or a copper alloy. Note that if the socket 10 is made of a metal or if the light-emitting module 20 generates little heat, the heat transfer unit 40 can be omitted.

[0028] The light emitting module 20 includes, for example, a substrate 21, a light emitting element 22, a frame portion 23, a sealing portion 24, and a circuit element 25.

[0029] The substrate 21 is provided on one end side of the socket 10. The substrate 21 can be adhered, for example, onto the heat transfer portion 40. If the heat transfer portion 40 is omitted, the substrate 21 can be adhered, for example, to the bottom surface 11a1 of the recess 11a. The adhesive used to adhere the substrate 21 is preferably an adhesive with high thermal conductivity. For example, the adhesive can be an adhesive mixed with a filler using a conductive material or an inorganic material.

[0030] Substrate 21 can be formed from, for example, an inorganic material such as ceramics (e.g., aluminum oxide or aluminum nitride), or an organic material such as paper phenol or glass epoxy. Substrate 21 may also be a metal core substrate in which the surface of a metal plate is covered with an insulating material. Substrate 21 may also have a single-layer structure or a multi-layer structure.

[0031] Furthermore, a wiring pattern 21a is provided on the surface of the substrate 21. The wiring pattern 21a is made of, for example, a material containing silver as a main component or a material containing copper as a main component.

[0032] Furthermore, a covering portion can be provided to cover the wiring pattern 21a, a film-like resistor (to be described later), etc. The covering portion can include, for example, a glass material.

[0033] The light emitting element 22 is provided on the substrate 21 (on the surface of the substrate 21 opposite to the socket 10 side). The light emitting element 22 is electrically connected to the wiring pattern 21a. At least one light emitting element 22 can be provided. When a plurality of light emitting elements 22 are provided, the plurality of light emitting elements 22 can be connected in series.

[0034] The light emitting element 22 may be, for example, a light emitting diode, an organic light emitting diode, a laser diode, or the like.

[0035] The light emitting element 22 may be any of a chip-type light emitting element, a surface-mounted light emitting element such as a PLCC (Plastic Leaded Chip Carrier) type, and a light emitting element having leads such as a bullet type. However, if the light emitting element 22 is a chip-shaped light emitting element, the light emitting module 20 can be made smaller, and therefore the vehicle lighting device 1 can be made smaller.

[0036] Therefore, in the following, as an example, a case where the light emitting element 22 is a chip-shaped light emitting element will be described. The chip-shaped light-emitting element 22 can be electrically connected to the wiring pattern 21a by COB (Chip On Board). The chip-shaped light-emitting element 22 may be any of an upper electrode type light-emitting element, a top and bottom electrode type light-emitting element, and a flip-chip type light-emitting element.

[0037] The frame portion 23 has a frame shape and surrounds the light-emitting element 22. The frame portion 23 can be adhered onto the substrate 21 using an adhesive. The outline (outline of the planar shape) of the frame portion 23 when viewed from a direction along the central axis 1a of the vehicle lighting device 1 can be changed as appropriate depending on the required light distribution characteristics, luminance distribution, etc. For example, the outline of the planar shape of the frame portion 23 illustrated in FIG. 1 is substantially rectangular.

[0038] The sealing portion 24 is provided inside the frame portion 23. The sealing portion 24 is provided so as to cover the area surrounded by the frame portion 23. The sealing portion 24 is provided so as to cover the light-emitting element 22. The sealing portion 24 contains a resin having light-transmitting properties. The resin is, for example, a silicone resin. The sealing portion 24 may also contain a phosphor.

[0039] If the light emitting element 22 is a surface-mounted light emitting element or a bullet-type light emitting element having lead wires, the frame portion 23 and the sealing portion 24 can be omitted.

[0040] The circuit element 25 can be a passive element or an active element used to configure the light-emitting circuit 20a having the light-emitting element 22. The circuit element 25 is provided on the substrate 21. The circuit element 25 is provided, for example, around the periphery of the frame portion 23 and is electrically connected to the wiring pattern 21a.

[0041] FIG. 3 is a circuit diagram illustrating the light-emitting circuit 20a. As shown in FIG. 3, the light emitting circuit 20a includes, for example, a light emitting element 22 and a circuit element 25.

[0042] The circuit elements 25 may be, for example, a control element 25a, a capacitor 25b, a resistor 25c, a first protection element 25d, and a second protection element 25e. However, the circuit elements 25 are not limited to the above examples. In addition to the above, the circuit elements 25 may also be, for example, a positive temperature coefficient thermistor, a negative temperature coefficient thermistor, an inductor, a surge absorber, a transistor, an integrated circuit, an arithmetic element, or the like.

[0043] The control element 25a can be electrically connected, for example, between the anode sides of the plurality of light-emitting elements 22 connected in series and the first protection element 25d. The control element 25a switches the number of light-emitting elements 22 to be turned on, for example, according to the voltage applied to the vehicle lighting device 1 (light-emitting module 20). The control element 25a can be, for example, an integrated circuit capable of controlling the total luminous flux by switching the number of light-emitting elements 22 to be turned on.

[0044] For example, a first protection element 25d and a second protection element 25e are electrically connected to the VIN terminal of the control element 25a. For example, a plurality of light-emitting elements 22 connected in series are electrically connected to the OUT terminal of the control element 25a. In this case, the anode side of the light-emitting element 22 is electrically connected to the OUT terminal. The cathode side of the light-emitting element 22 is electrically connected to the vehicle ground, such as the chassis of the vehicle body. In the case of the light-emitting circuit 20a illustrated in FIG. 3, four light-emitting elements 22 connected in series are electrically connected to the OUT terminal of the control element 25a.

[0045] The IR terminal of the control element 25a is electrically connected to, for example, some of the plurality of series-connected light-emitting elements 22. In the case of the light-emitting circuit 20a illustrated in Fig. 3, one of the four series-connected light-emitting elements 22 is electrically connected to the IR terminal of the control element 25a. The GND terminal is electrically connected to, for example, the source electrode S of the field-effect transistor 25d1.

[0046] When the voltage applied to the vehicle lighting device 1 drops, the total luminous flux of the light emitted from the vehicle lighting device 1 decreases, and there is a risk that the total luminous flux will fall below a specified value. The control element 25a switches the number of light-emitting elements 22 to be turned on in accordance with the voltage applied to the vehicle lighting device 1.

[0047] For example, when the voltage applied to the vehicle lighting device 1 is high (for example, when the rated voltage is about 13.5 V), the control element 25a causes the output current Ia to flow through the OUT terminal to all of the plurality of series-connected light-emitting elements 22. In this case, light is emitted from all of the light-emitting elements 22. In the case of the light-emitting circuit 20a illustrated in FIG. 3, the output current Ia flows to all of the four series-connected light-emitting elements 22.

[0048] For example, when the voltage applied to the vehicle lighting device 1 is reduced (for example, to about 6 V), the control element 25a causes the output current Ia to flow through the light-emitting elements 22 electrically connected between the OUT terminal and the IR terminal. Reducing the number of light-emitting elements 22 to be turned on can reduce the voltage drop. Therefore, even if the voltage applied to the vehicle lighting device 1 is reduced and the output current Ia is reduced, it is possible to prevent the total luminous flux from falling below a specified value.

[0049] Furthermore, depending on the temperature of the atmosphere in which the vehicle lighting device 1 is installed, when the vehicle lighting device 1 is turned on, the temperature of the light-emitting element 22 may become too high and exceed the maximum junction temperature. If the temperature of the light-emitting element 22 exceeds the maximum junction temperature, the light-emitting element may break down or the function of the light-emitting element 22 may be degraded.

[0050] Therefore, the control element 25a may be capable of performing temperature derating. For example, at least one of a positive temperature coefficient thermistor and a negative temperature coefficient thermistor may be provided on the substrate 21, and the control element 25a may perform temperature derating based on changes in the resistance value of the thermistor. Furthermore, the control element 25a may be capable of switching the number of light-emitting elements 22 to be turned on and performing temperature derating. That is, the control element 25a can be configured to perform at least one of switching the number of light-emitting elements 22 to be turned on and temperature derating depending on the voltage applied to the vehicle lighting device 1 (light-emitting module 20).

[0051] Capacitor 25b is connected in parallel with control element 25a, for example. Capacitor 25b can be provided, for example, to smooth the voltage applied to control element 25a or to provide noise suppression. Note that while FIG. 3 illustrates an example in which two series-connected capacitors 25b and two series-connected capacitors 25b are connected in parallel, the number and connection form of capacitors 25b can be changed as needed. Capacitor 25b can also be omitted.

[0052] Furthermore, a capacitor 25b1 may be provided that is connected in parallel with the light-emitting element 22. The capacitor 25b1 may be provided, for example, to smooth the voltage applied to the light-emitting element 22 or to reduce noise. The number and connection form of the capacitors 25b1 may be changed as needed. The capacitor 25b1 may also be omitted.

[0053] The resistor 25c is electrically connected to the Vsense terminal of the control element 25a. The control element 25a sets the voltage for switching the number of light-emitting elements 22 to be turned on based on the resistance value of the resistor 25c. Therefore, the resistor 25c may have an adjustable resistance value. For example, the resistor 25c may be a variable resistor or a film resistor that can be laser trimmed.

[0054] Here, due to vibrations caused by running, etc., a pulse noise (negative voltage pulse) may be applied from the reverse direction to the vehicle lighting device 1 (light-emitting circuit 20a) due to a counter electromotive force of a circuit provided in the vehicle. Also, if the electrical connection to the battery is incorrect, a reverse voltage (negative voltage) may be applied to the vehicle lighting device 1. If such a negative surge is applied to the control element 25a or the light emitting element 22, the vehicle lighting device 1 may break down or its functions may be degraded.

[0055] Therefore, the light emitting circuit 20a is provided with a first protection element 25d. In this case, connecting a diode between the power supply terminal 31 on the Vin side and the VIN terminal of the control element 25a can prevent the negative surge from being applied to the control element 25a and the light-emitting element 22. However, doing so means that a diode is connected in series to the multiple light-emitting elements 22 that are connected in series, which increases the voltage drop.

[0056] As described above, the control element 25a reduces the number of light-emitting elements 22 that are turned on when the voltage applied to the vehicle lighting device 1 is low. However, if the voltage drop increases due to the diodes being connected in series, there is a risk that the total luminous flux will fall below the specified value even if an attempt is made to ensure the total luminous flux by reducing the number of light-emitting elements 22 that are turned on.

[0057] Therefore, the first protection element 25d is provided with a field effect transistor (FET) 25d1, which can be electrically connected between the power supply terminal 31 on the Vin side and the VIN terminal of the control element 25a via a resistor. That is, the field effect transistor 25d1 is electrically connected between the anode and cathode of the light emitting element 22 and the DC power supply.

[0058] In this case, the field-effect transistor 25d1 may be an n-channel field-effect transistor or a p-channel field-effect transistor. The field-effect transistor 25d1 illustrated in FIG. 3 is an n-channel field-effect transistor.

[0059] When the field-effect transistor 25d1 is an n-channel field-effect transistor, as shown in FIG. 3, the gate electrode G is electrically connected between the power supply terminal 31 on the Vin side and the VIN terminal of the control element 25a, the drain electrode D is electrically connected to the power supply terminal 31 on the GND side, and the source electrode S is connected to the GND or cathode of the circuit element 25. When a voltage is supplied from the battery, the field-effect transistor 25d1 becomes conductive, and the GND or cathode of the circuit element 25 is electrically connected to the ground of the vehicle, such as the chassis.

[0060] That is, when the field-effect transistor 25d1 is an n-channel field-effect transistor, the gate electrode G of the n-channel field-effect transistor is electrically connected between the positive side of a DC power supply and the anode side of the light-emitting element 22. The drain electrode D of the n-channel field-effect transistor is electrically connected to the negative side of the DC power supply and the varistor 25d2, which will be described later. The source electrode S of the n-channel field-effect transistor is electrically connected to other circuit elements 25 provided in the light-emitting circuit 20a, other than the varistor 25d2. That is, the source electrode S of the n-channel field-effect transistor is not electrically connected to the varistor 25d2.

[0061] When a negative surge is applied to the field effect transistor 25d1 (n-channel field effect transistor), the field effect transistor 25d1 is turned off, and therefore no reverse voltage is applied to the light-emitting circuit 20a, thereby protecting the light-emitting circuit 20a.

[0062] When the field-effect transistor 25d1 is a p-channel field-effect transistor, the gate electrode G is electrically connected to the ground of the vehicle, such as the chassis of the vehicle body, the drain electrode D is electrically connected to the power supply terminal 31 on the Vin side, and the source electrode S is electrically connected to the VIN terminal of the control element 25a.

[0063] When a negative surge is applied to the field effect transistor 25d1 (p-channel field effect transistor), the field effect transistor 25d1 is turned off, and therefore no reverse voltage is applied to the light-emitting circuit 20a, thereby protecting the light-emitting circuit 20a.

[0064] As described above, if the field effect transistor 25d1 is provided, the negative surge applied to the control element 25a and the light emitting element 22 can be suppressed.

[0065] Furthermore, since the field effect transistor 25d1 has a smaller voltage drop than a diode, it is easy to ensure that the total luminous flux is equal to or greater than the specified value even when the voltage applied to the vehicle lighting device 1 is low.

[0066] Although the field-effect transistor 25d1 may be either an n-channel field-effect transistor or a p-channel field-effect transistor, if the field-effect transistor 25d1 is an n-channel field-effect transistor, the field-effect transistor 25d1 will not turn on when a negative surge is applied. Therefore, even when the field-effect transistor 25d1 and the second protection element 25e are connected in parallel, it is possible to prevent a negative surge from being applied to the second protection element 25e.

[0067] Furthermore, n-channel field-effect transistors have the advantages of superior switching characteristics, high availability, and low cost compared to p-channel field-effect transistors.

[0068] Here, a high withstand voltage (for example, about −600 V) against a negative surge voltage (reverse voltage) is required for the vehicle lighting device 1. Since the field-effect transistor 25d1 having a high withstand voltage increases in size, it is difficult to simply provide the field-effect transistor 25d1 in the vehicle lighting device 1, which is required to be compact.

[0069] Furthermore, the on-resistance of the field-effect transistor 25d1 increases rapidly when the withstand voltage reaches approximately 300 V to 400 V. Therefore, if the field-effect transistor 25d1 has a high withstand voltage, the voltage drop described above increases, and when the voltage applied to the vehicle lighting device 1 decreases, the total luminous flux may fall below the specified value.

[0070] 3, the first protection element 25d is provided with a varistor 25d2 connected in parallel with the field-effect transistor 25d1. The provision of the varistor 25d2 makes it possible to keep the negative surge voltage applied to the field-effect transistor 25d1 below the limiting voltage of the varistor. This makes it possible to select a field-effect transistor 25d1 with a low withstand voltage, thereby enabling the selection of a small-sized field-effect transistor 25d1 to reduce the size of the vehicle lighting device 1 and suppress the voltage drop described above.

[0071] For example, it is preferable that the withstand voltage of field-effect transistor 25d1 is equal to or less than 100 V. In this case, the varistor voltage of varistor 25d2 should be such that when a negative surge voltage (reverse voltage) of about −600 V is applied to vehicle lighting device 1, a negative surge voltage (reverse voltage) exceeding the withstand voltage of field-effect transistor 25d1 is not applied to field-effect transistor 25d1.

[0072] The above describes a case where a negative surge is applied to the vehicle lighting device 1, but a positive surge may also be applied to the vehicle lighting device 1. For example, if a large power load such as a heating / cooling device is suddenly turned off, the battery voltage may overshoot. If such a positive surge is applied to the control element 25a, the light emitting element 22, or the like, the vehicle lighting device 1 may break down or its functions may be degraded.

[0073] Therefore, the light emitting circuit 20a is provided with a second protection element 25e. The second protection element 25e can be connected in parallel with the first protection element 25d. The second protection element 25e can be, for example, a Zener diode. In this case, the second protection element 25e is preferably, for example, a surge absorbing diode (TVS: Transient Voltage Suppressor). The cathode side of the Zener diode is electrically connected between the power supply terminal 31 on the Vin side and the VIN terminal of the control element 25a. The anode side of the Zener diode is electrically connected to the vehicle ground, such as the chassis of the vehicle body.

[0074] That is, the cathode side of the Zener diode is electrically connected to the positive side of the DC power supply, and the anode side of the Zener diode is electrically connected to the source electrode S of the field effect transistor 25d1.

[0075] If the second protection element 25e is provided, the positive surge voltage can be reduced to the clamp voltage of the Zener diode, thereby preventing excessive voltage from being applied to the control element 25a, the first protection element 25d, and the light-emitting element 22.

[0076] Furthermore, since the light-emitting element 22 has a low withstand voltage, if a portion of the positive surge is applied to the light-emitting element 22 via the control element 25a, the light-emitting element 22 may fail. Therefore, a third protection element 25f may be further provided, connected in parallel with the light-emitting element 22. The third protection element 25f may be, for example, the same as the second protection element 25e. That is, the third protection element 25f may be a Zener diode. In this case, the third protection element 25f is preferably, for example, a surge absorbing diode. The cathode side of the Zener diode may be connected in parallel with the anode side of the light-emitting element 22. The anode side of the Zener diode is electrically connected to the vehicle ground, such as the chassis of the vehicle body.

[0077] (vehicle lighting fixtures)

[0078] In one embodiment of the present invention, a vehicle lamp 100 can be provided that includes the vehicle lighting device 1. The above-mentioned description of the vehicle lighting device 1 and modified versions of the vehicle lighting device 1 (for example, versions in which a person skilled in the art appropriately adds, deletes, or modifies components, and which still have the features of the present invention) can all be applied to the vehicle lamp 100.

[0079] In the following, as an example, a case will be described in which the vehicular lamp 100 is a front combination light installed in an automobile. However, the vehicular lamp 100 is not limited to a front combination light installed in an automobile. The vehicular lamp 100 may be any vehicular lamp that is installed in an automobile, a railroad car, or the like.

[0080] FIG. 4 is a schematic partial cross-sectional view illustrating the vehicle lamp 100. As shown in FIG. As shown in FIG. 4, the vehicle lamp 100 includes, for example, the vehicle lighting device 1, a housing 101, a cover 102, an optical element 103, a seal member 104, and a connector 105.

[0081] The vehicle lighting device 1 is attached to the housing 101. The housing 101 holds the mounting portion 11. The housing 101 is box-shaped with one end open. The housing 101 is formed, for example, from a light-opaque resin. The bottom surface of the housing 101 is provided with a mounting hole 101a into which the portion of the mounting portion 11 provided with the bayonet 12 is inserted. A recess is provided around the periphery of the mounting hole 101a into which the bayonet 12 provided on the mounting portion 11 is inserted. Note that although the case where the mounting hole 101a is directly provided in the housing 101 has been exemplified, a mounting member having the mounting hole 101a may also be provided on the housing 101.

[0082] When attaching the vehicle lighting device 1 to the vehicle lamp 100, the portion of the mounting portion 11 where the bayonet 12 is provided is inserted into the mounting hole 101a, and the vehicle lighting device 1 is rotated. Then, for example, the bayonet 12 is held in a fitting portion provided on the periphery of the mounting hole 101a. This type of attachment method is called a twist lock.

[0083] The cover 102 is provided so as to cover the opening of the housing 101. The cover 102 is made of a light-transmitting resin or the like. The cover 102 may also have a function such as a lens.

[0084] Light emitted from the vehicle lighting device 1 is incident on the optical element 103. The optical element 103 reflects, diffuses, guides, and collects the light emitted from the vehicle lighting device 1, and forms a predetermined light distribution pattern. For example, the optical element 103 illustrated in FIG. 4 is a reflector. In this case, the optical element 103 reflects the light emitted from the vehicle lighting device 1 and forms a predetermined light distribution pattern.

[0085] The seal member 104 is provided between the flange 13 and the housing 101. The seal member 104 has an annular shape and is made of an elastic material such as rubber or silicone resin.

[0086] When the vehicle lighting device 1 is attached to the vehicle lamp 100, the seal member 104 is sandwiched between the flange 13 and the housing 101. Therefore, the seal member 104 can seal the internal space of the housing 101. Furthermore, the elastic force of the seal member 104 presses the bayonet 12 against the housing 101. Therefore, the vehicle lighting device 1 can be prevented from detaching from the housing 101.

[0087] The connector 105 is fitted to the ends of the plurality of power supply terminals 31 exposed inside the connector holder 15. A lighting circuit and the like are electrically connected to the connector 105. Therefore, by fitting the connector 105 to the ends of the plurality of power supply terminals 31, the lighting circuit and the like can be electrically connected to the light-emitting element 22.

[0088] Furthermore, a seal member 105a is provided on the connector 105. When the connector 105 having the seal member 105a is inserted into the inside of the connector holder 15, the inside of the connector holder 15 is sealed so as to be watertight.

[0089] Although several embodiments of the present invention have been described above, these embodiments are presented by way of example only and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, etc. can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

[0090] The following are additional notes regarding the above-described embodiment.

[0091] (Appendix 1) at least one light emitting element; a field-effect transistor electrically connected between the anode and cathode sides of the light-emitting element and a DC power source; a varistor connected in parallel with the field effect transistor; A light emitting module comprising:

[0092] (Appendix 2) the field-effect transistor is an n-channel field-effect transistor, a gate electrode of the n-channel field effect transistor is electrically connected between a positive side of the DC power supply and an anode side of the light emitting element via a resistor, and is electrically connected to a source electrode of the n-channel field effect transistor via a resistor; a drain electrode of the n-channel field effect transistor is electrically connected to the negative side of the DC power supply and the varistor; 2. The light-emitting module according to claim 1, wherein the source electrode of the n-channel field-effect transistor is not electrically connected to the varistor.

[0093] (Appendix 3) further comprising a Zener diode connected in parallel with the field effect transistor; a cathode side of the Zener diode electrically connected to a positive side of the DC power supply; 3. The light-emitting module according to claim 1, wherein the anode side of the Zener diode is electrically connected to the source electrode of the field-effect transistor.

[0094] (Appendix 4) a control element electrically connected between the anode side of the plurality of light-emitting elements connected in series and the field-effect transistor; The light-emitting module according to any one of appendices 1 to 3, wherein the control element is capable of switching the number of light-emitting elements to be lit depending on the voltage applied to the light-emitting module, and performing at least one of temperature derating.

[0095] (Appendix 5) A light-emitting module according to any one of appendices 1 to 4; a socket in which the light emitting module is provided; A vehicle lighting device equipped with:

[0096] (Appendix 6) a vehicle lighting device according to claim 5; a housing in which the vehicle lighting device is mounted; A vehicle lighting fixture equipped with: [Explanation of symbols]

[0097] 1 Vehicle lighting device, 10 Socket, 20 Light-emitting module, 20a Light-emitting circuit, 21 Board, 22 Light-emitting element, 25 Circuit element, 25a Control element, 25b Capacitor, 25c Resistor, 25d First protection element, 25d1 Field-effect transistor, 25d2 Varistor, 25e Second protection element, 25f Third protection element, 100 Vehicle lamp, 101 Housing

Claims

1. at least one light emitting element; a field-effect transistor electrically connected between the anode and cathode sides of the light-emitting element and a DC power source; a varistor connected in parallel with the field effect transistor; A light emitting module comprising:

2. the field-effect transistor is an n-channel field-effect transistor, a gate electrode of the n-channel field effect transistor is electrically connected between a positive side of the DC power supply and an anode side of the light emitting element via a resistor, and is electrically connected to a source electrode of the n-channel field effect transistor via a resistor; a drain electrode of the n-channel field effect transistor is electrically connected to the negative side of the DC power supply and to the varistor; 2. The light-emitting module according to claim 1, wherein the source electrode of the n-channel field-effect transistor is not electrically connected to the varistor.

3. further comprising a Zener diode connected in parallel with the field effect transistor; a cathode side of the Zener diode electrically connected to a positive side of the DC power supply; 3. The light-emitting module according to claim 1, wherein the anode side of the Zener diode is electrically connected to the source electrode of the field-effect transistor.

4. a control element electrically connected between the anode side of the plurality of light-emitting elements connected in series and the field-effect transistor; 3. The light-emitting module according to claim 1, wherein the control element is capable of performing at least one of switching the number of the light-emitting elements to be turned on and temperature derating in accordance with a voltage applied to the light-emitting module.

5. A light emitting module according to claim 1 or 2; a socket in which the light emitting module is provided; A vehicle lighting device equipped with:

6. The vehicle lighting device according to claim 5; a housing to which the vehicle lighting device is attached; A vehicle lighting fixture equipped with:

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