Lighting circuit, light-emitting module

Abstract

This provides a lighting circuit that can protect elements connected to a power line. [Solution] A lighting circuit comprising: a first transistor connected in series with a light source provided between a power line and a ground line; a constant current circuit that generates a constant current flowing to the light source when the first transistor is turned on and stops generating the constant current when the first transistor is turned off; a Zener diode having a cathode connected to the power line and an anode; and a second transistor having a base connected to the anode, an emitter connected to the ground line, and a collector connected to the control electrode of the first transistor.

Description

Technical Field

[0007]

[0001] The present invention relates to a lighting circuit and a light emitting module.

Background Art

[0002] There is a lighting circuit that operates based on a power supply voltage from a vehicle battery (see, for example, Patent Document 1).

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a lighting circuit, a Zener diode for protecting elements such as a light source and elements included in the lighting circuit may be connected between a power supply line and a ground line. When only a Zener diode is connected between the power supply line and the ground line, it is necessary to use a Zener diode with a high breakdown voltage.

[0005] Generally, since the parasitic capacitance of a Zener diode with a high breakdown voltage is large, when the voltage of the power supply line rises, the Zener diode may not operate, and a high voltage may continue to be applied to elements such as a light source and a switch connected to the power supply line.

[0006] The present invention has been made in view of the above conventional problems, and an object thereof is to provide a lighting circuit that can protect an element connected to a power supply line.

Means for Solving the Problems

[0007] A primary aspect of the present invention that solves the aforementioned problems is a lighting circuit comprising: a first transistor connected in series with a light source provided between a power line and a ground line; a constant current circuit that generates a constant current flowing to the light source when the first transistor is turned on and stops generating the constant current when the first transistor is turned off; a Zener diode having a cathode connected to the power line and an anode; and a second transistor having a base connected to the anode, an emitter connected to the ground line, and a collector connected to the control electrode of the first transistor. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a lighting circuit that can protect elements connected to a power line. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of a lighting circuit 10. [Figure 2] This is a plan view of the light-emitting module 100. [Figure 3] This is a schematic diagram of the light-emitting module 100. [Figure 4] This is a schematic diagram of the light-emitting module 101. [Modes for carrying out the invention]

[0010] This specification and the accompanying drawings make at least the following matters clear. Furthermore, identical or equivalent components, members, etc., shown in each drawing are denoted by the same reference numerals, and redundant explanations are omitted where appropriate.

[0011] Furthermore, in this embodiment, "connection" refers to a state in which two components are electrically connected unless otherwise specified. Therefore, "connection" includes not only cases where two components are connected not only by wiring, but also, for example, by a resistor.

[0012] =====Lighting Circuit 10 (Configuration)===== Figure 1 shows an example of the lighting circuit 10 of this embodiment. Here, we will first explain the configuration of the lighting circuit 10. The lighting circuit 10 is a circuit that lights up a light source 11 used in vehicle lighting equipment, and is composed of terminals 20, 21, a power line 22, a ground line 23, a MOS transistor 30, a constant current circuit 31, a Zener diode 32, a transistor 33, and resistors R3, R4.

[0013] The light source 11 is, for example, a light source used in a vehicle's clearance lamp, and is equipped with a plurality (for example, three) of light-emitting elements (not shown). The light-emitting elements in this embodiment are, for example, light-emitting diodes (LEDs), but may also be other semiconductor light-emitting elements such as laser diodes (LDs) or organic EL elements.

[0014] In this embodiment, the light source 11 includes multiple light-emitting elements, but for example, the light source 11 may be composed of only one light-emitting element.

[0015] Terminal 20 is a "power terminal" to which the power supply voltage Vb from the vehicle's battery is applied, and terminal 21 is a "ground terminal" to which the ground voltage is applied. The power line 22 is connected to terminal 20, and the ground line 23 is connected to terminal 21. The light source 11 is located between the power line 22 and the ground line 23.

[0016] The MOS transistor 30 is a switch that controls the illumination of the light source 11, and is connected in series with the light source 11.

[0017] The constant current circuit 31 generates a constant current Ic that flows to the light source 11 when the MOS transistor 30 is turned on, and stops generating the constant current Ic when the MOS transistor 30 is turned off. The constant current circuit 31 is composed of resistors 40, 41, transistor 42, and resistors R1, R2.

[0018] Resistor 40 is provided between the power supply line 22 and the gate of MOS transistor 30, and resistor 41 is provided between the source of MOS transistor 30 and the ground line 23. Note that the MOS transistor corresponds to the "first transistor", and the gate of the MOS transistor corresponds to the "control electrode".

[0019] Transistor 42 is an NPN bipolar transistor and has a base connected to resistor 41, an emitter connected to the ground line 23, and a collector connected to resistor 40. In this embodiment, the base of transistor 42 and resistor 41 are connected via a base resistor R1. Also, resistor R2 is a pull-down resistor connected between the base and emitter of transistor 42. Transistor 42 corresponds to the "third transistor", resistor 40 corresponds to the "first resistor", and resistor 41 corresponds to the "second resistor".

[0020] Zener diode 32 and transistor 33 are circuits that protect the light source 11 and MOS transistor 30 from overvoltage when the power supply voltage Vb applied to the power supply line 22 rises. Details will be described later, but "overvoltage" refers to a state where the voltage applied to the power supply line 22 greatly increases from a normal battery voltage (for example, 12 to 14V) to, for example, 65V or more (for example, 65V to 87V).

[0021] Zener diode 32 has a cathode connected to the power supply line 22 and an anode connected to transistor 33 described later. Transistor 33 has a base connected to the anode of zener diode 32, an emitter connected to the ground line 23, and a collector connected to the gate of MOS transistor 30.

[0022] Note that the base of transistor 33 and the anode of zener diode 32 are connected via a base resistor R3. Resistor R4 is a pull-down resistor connected between the base and emitter of transistor 33. Transistor 33 corresponds to the "second transistor".

[0023] =====Lighting Circuit 10 (Operation)===== Here, the operation of the lighting circuit 10 of this embodiment will be explained with reference to Figure 1. In this embodiment, the threshold voltage of the MOS transistor 30 is several volts (for example, 2V), the threshold voltages of transistors 33 and 42 are, for example, 0.7V, and the breakdown voltage of the Zener diode 32 is, for example, 60V. Although only one Zener diode 32 is shown in Figure 1 for convenience, multiple Zener diodes may be connected in series so that the breakdown voltage is, for example, 60V.

[0024] <<When the power supply voltage Vb is at a normal level>> First, let's describe the case where a normal level power supply voltage Vb (for example, 12V) is applied to the power supply line 22. When the power supply voltage Vb is applied to terminal 20, the power supply voltage Vb is also applied to the gate of the MOS transistor 30 via resistor 40. As a result, the MOS transistor 30 turns on.

[0025] When the MOS transistor 30 is turned on, current flows from the power line 22 through the light source 11 and the MOS transistor 30 to the resistor 41. As a result, the voltage Vc at the node to which the MOS transistor 30 and the resistor 41 are connected rises. When the voltage Vc exceeds the threshold voltage of the transistor 42 (for example, 0.7V), the transistor 42 turns on.

[0026] As a result, after the MOS transistor 30 is turned on, the voltage Vc is clamped at 0.7V. Here, if the resistance value of resistor 41 is Rc, then a constant current Ic, as shown in equation (1), flows through resistor 41. Ic = Rc / Vc = Rc / 0.7 ... (1)

[0027] Therefore, when the MOS transistor 30 is turned on, the constant current circuit 31 supplies a constant current Ic to the light source 11, causing the light source 11 to light up with a brightness corresponding to the constant current Ic. Note that in this case, the power supply voltage Vb (e.g., 12V) applied to the power supply line 22 is lower than the breakdown voltage of the Zener diode 32 (e.g., 60V). Therefore, the transistor 33 is turned off.

[0028] Furthermore, when the application of the power supply voltage Vb to the power supply line 22 is stopped, the voltage across the power supply line 22 gradually decreases to the ground voltage (0V) through resistors (not shown). As a result, the MOS transistor 30 turns off, and the generation of the constant current Ic is also stopped.

[0029] Thus, in the lighting circuit 10, when the power supply voltage Vb is applied to the power supply line 22, a constant current Ic flows to the light source 11, causing the light source 11 to light up. On the other hand, when the application of the power supply voltage Vb to the power supply line 22 is stopped, the generation of the constant current Ic stops, causing the light source 11 to turn off.

[0030] <<If the power supply voltage Vb is overvoltage>> Next, we will explain the case where the power supply voltage Vb applied to the power supply line 22 becomes an overvoltage (for example, 65V). Note that overvoltage can occur when the relay (not shown) between the vehicle battery and the power supply line 22 turns off, due to the impedance of the wiring between the vehicle battery and the power supply line 22. For this reason, we will explain the operation of the lighting circuit 10 when, for example, the voltage on the power supply line 22 changes from a normal level power supply voltage Vb (for example, 12V) to an overvoltage.

[0031] When the voltage of the power line 22 becomes an overvoltage from the normal power supply voltage Vb, the cathode and anode voltages of the Zener diode 32 in Figure 1 become higher than the breakdown voltage. As a result, the Zener diode 32 breaks down, and the base voltage of the transistor 33 becomes higher than the threshold voltage of the transistor 33. Consequently, the transistor 33 turns on, and the gate of the MOS transistor 30 becomes the ground voltage via the transistor 33.

[0032] Therefore, the MOS transistor 30 turns off. In this way, when the voltage of the power supply line 22 becomes overvoltage, the MOS transistor 30 turns off. Therefore, when the voltage of the power supply line 22 is overvoltage, no current flows to the light source 11 and the MOS transistor 30, and the light source 11 and the MOS transistor 30 are properly protected.

[0033] =====Plan view of the light-emitting module 100===== Figure 2 is a plan view of the light-emitting module 100. The light-emitting module 100 in this embodiment includes a lighting circuit 10, a light source 11, and a substrate 110. Although the light-emitting module 100 also includes components other than the lighting circuit 10, light source 11, and substrate 110, this description will focus on the substrate 110.

[0034] The circuit board 110 is a circuit board on which multiple components included in the lighting circuit 10 and the light source 11 are mounted. The light source 11, terminals 20 and 21, MOS transistor 30, Zener diode 32, transistors 33 and 42, and resistors 40 and 41 are mounted on the +z side of the circuit board 110 (hereinafter referred to as the "front side" as appropriate).

[0035] In this example, transistor 33 is a single component including resistors R3 and R4, and transistor 42 is a single component including resistors R1 and R2. Therefore, the illustration of resistors R1 to R4 is omitted on the front side of circuit board 110.

[0036] As shown in Figure 2, the substrate 110 has a quadrilateral shape in plan view. Here, the direction along the left-right edges of the substrate 110 is defined as the "x direction," and the direction along the front-to-back direction of the substrate 110 is defined as the "y direction." The direction perpendicular to the front surface of the substrate 110 is defined as the "z direction." The front surface of the substrate 110 corresponds to the "first surface," and the back surface of the substrate 110 corresponds to the "second surface."

[0037] Near the +y side edge of the front surface of the circuit board 110, terminals 20 and 21 are mounted, which connect to two cables (not shown) from the vehicle's battery. Also, near the center of the circuit board 110 (in this case, the geometric center), a light source 11 that generates a large amount of heat is mounted.

[0038] As shown in the enlarged view of Figure 2, the light source 11 includes, for example, three light-emitting elements 80-82. Therefore, in this embodiment, each of the three light-emitting elements 80-82 of the light source 11 is positioned near the center of the substrate 110.

[0039] Furthermore, in this embodiment, on the front surface of the substrate 110, the Zener diode 32 and the MOS transistor 30 are arranged such that the distance L1 (dotted line in the figure) between the terminal 20 and the Zener diode 32 is shorter than the distance L2 (dotted line in the figure) between the terminal 20 and the MOS transistor 30. Therefore, on the substrate 110, the parasitic elements from terminal 20 to the Zener diode 32 can be made smaller than the parasitic elements from terminal 20 to the MOS transistor 30. Note that "parasitic elements" include, for example, parasitic capacitance, parasitic resistance, and parasitic inductance of wiring (not shown) on the substrate 110.

[0040] As a result, if an overvoltage is applied to the power line 22 via terminal 20, the Zener diode 32 will break down in a shorter time, thus protecting the light source 11 and the MOS transistor 30.

[0041] "Distance L1" refers to, for example, the distance between the geometric center of terminal 20 in a plan view and the geometric center of the package of the Zener diode 32, and "Distance L2" refers to, for example, the distance between the geometric center of terminal 20 in a plan view and the geometric center of the package of the MOS transistor 30. "Electronic component package" refers to the part formed from resin or the like that constitutes the outer shape of the electronic component. Distance L1 corresponds to the "first distance," and distance L2 corresponds to the "second distance."

[0042] Furthermore, in this embodiment, among the multiple components included in the lighting circuit 10, the Zener diode 32, which generates a large amount of heat, and the MOS transistor 30 are arranged so that the distance between them is increased. Specifically, the Zener diode 32 is placed in the +x and +y regions from the position of the light source 11 on the substrate 110 (the geometric center of the substrate 110), and the MOS transistor 30 is placed in the -x and -y regions. By arranging them in this way, heat on the substrate 110 can be dispersed.

[0043] Furthermore, while maintaining the position of the Zener diode 32 on the substrate 110, the MOS transistor 30 may be arranged in regions on the -x side and +y side, for example, from the position of the light source 11 (the geometric center of the substrate 110). Even in such a case, heat on the substrate 110 can be dispersed in the same way as in this embodiment. In this embodiment, for example, the +x direction corresponds to the "first direction," and the -x direction corresponds to the "second direction."

[0044] =====Schematic diagram of light-emitting module 100===== Figure 3 is a schematic diagram of the light-emitting module 100. The light-emitting module 100 consists of a lighting circuit 10, a light source 11, a substrate 110, a heat dissipation member 111, and an adhesive 112. For convenience, only the MOS transistor 30, Zener diode 32, and light-emitting element 80 of the lighting circuit 10 and light source 11 mounted on the substrate 110 are shown in this diagram.

[0045] The lower part of Figure 3 schematically shows cross-sections of the substrate 110 at the locations where the MOS transistor 30, Zener diode 32, and light-emitting element 80 are positioned. For example, at the location where the Zener diode 32 is positioned, the cross-section of the substrate 110 along line AA in the enlarged view of the Zener diode 32 (upper part of Figure 3) is schematically shown. The same applies to the cross-sections of the substrate 110 at the locations of the MOS transistor 30 and the light-emitting element 80, so a detailed explanation is omitted here.

[0046] Pads 210 and 211 for mounting the Zener diode 32 are formed on the front surface of the substrate 110. Furthermore, pads 220 and 221 for mounting the light-emitting element 80 and pads 230 and 231 for mounting the MOS transistor 30 are formed on the front surface of the substrate 110. Note that each of the pads 210, 211, 220, 221, 230, and 231 is a quadrilateral conductive pattern formed on the front surface of the substrate 110.

[0047] Furthermore, a metal heat dissipation member 111 is attached to the back surface (-z direction surface) of the substrate 110 via an adhesive 112. In this embodiment, the heat dissipation member 111 is, for example, an aluminum plate, but is not limited to this, and may be a member made of other metals or materials with high thermal conductivity. In addition, a heat dissipation silicone adhesive is used as the adhesive 112 so as to be able to bond the resin substrate 110 and the aluminum heat dissipation member 111. However, the adhesive 112 is not limited to a heat dissipation silicone adhesive as long as it can bond the substrate 110 and the heat dissipation member 111.

[0048] As shown in the enlarged view of Figure 3, eight heat dissipation sections 200a to 200g are formed in the substrate 110 in the -z direction at the location where the Zener diode 32 is mounted. Heat dissipation section 200a is a cylindrical portion formed by filling a through-hole (so-called via) formed in the z direction of the substrate 110 with, for example, a conductive paste. Note that the material constituting the heat dissipation section 200a is not limited to conductive paste, but any material with high thermal conductivity is acceptable.

[0049] Since the heat dissipation sections 200b to 200g are the same as the heat dissipation section 200a, a detailed explanation is omitted here. Thus, in this embodiment, heat dissipation sections 200b to 200g are formed on the substrate 110 between the Zener diode 32 and the heat dissipation member 111, dissipating the heat generated by the Zener diode 32 to the heat dissipation member 111.

[0050] Therefore, in this embodiment, the Zener diode 32 can be adequately protected from heat. Hereinafter, the heat dissipation portions 200b to 200g of the substrate 110 will be referred to as "heat dissipation structure A". Furthermore, heat dissipation structure A corresponds to the first heat dissipation structure.

[0051] Furthermore, in this embodiment, the heat from the Zener diode 32 is dissipated to the heat dissipation member 111 via the heat dissipation sections 200a to 200g and the adhesive 112, but for convenience, it will be explained as if the heat is dissipated from the heat dissipation sections 200a to 200g to the heat dissipation member 111.

[0052] On the substrate 110, eight heat dissipation sections 201a to 201g are formed in the -z direction at the position where the light-emitting element 80 is mounted. Each of the heat dissipation sections 201a to 201g is the same as heat dissipation section 200a except for the position in which they are formed, so a detailed explanation is omitted here. Therefore, in this embodiment, the light-emitting element 80 can be adequately protected from heat. In addition, the light-emitting elements 81 and 82 included in the light source 11 also have a heat dissipation structure similar to the eight heat dissipation sections 201a to 201g formed on the substrate 110. Therefore, in this embodiment, the light source 11 can be adequately protected from heat.

[0053] On the substrate 110, four heat dissipation sections 202a to 202d are formed in the -z direction at the position where the MOS transistor 30 is mounted. Each of the heat dissipation sections 202a to 202d is the same as heat dissipation section 200a except for the position in which they are formed, so a detailed explanation is omitted here. Therefore, in this embodiment, the MOS transistor 30 can be adequately protected from heat. Hereafter, the heat dissipation sections 202a to 202d of the substrate 110 will be referred to as the "second heat dissipation structure B". Furthermore, heat dissipation structure B corresponds to the second heat dissipation structure.

[0054] Furthermore, in this embodiment, the heat dissipation structure A in the -z direction of the Zener diode 32 on the substrate 110 has four more heat dissipation parts than the heat dissipation structure B in the -z direction of the MOS transistor 30. Therefore, the thermal conductivity of heat dissipation structure A is higher than that of heat dissipation structure B. Thus, in this embodiment, when the power supply voltage Vd of the power supply line 22 becomes overvoltage, the Zener diode 32, which generates more heat than the MOS transistor 30, can dissipate heat more effectively.

[0055] In this embodiment, the number of heat dissipation parts in heat dissipation structure A is greater than the number of heat dissipation parts in heat dissipation structure B. However, this configuration is not limited to this, as long as the thermal conductivity of heat dissipation structure A is higher than the thermal conductivity of heat dissipation structure B. For example, even if the number of heat dissipation parts in heat dissipation structure A and heat dissipation structure B are the same, if the material of the heat dissipation parts in heat dissipation structure A has a higher thermal conductivity than the material of the heat dissipation parts in heat dissipation structure B, the same effect as in this embodiment can be obtained.

[0056] =====Schematic diagram of light-emitting module 101===== Figure 4 is a schematic diagram of the light-emitting module 101. The light-emitting module 101 consists of a lighting circuit 10, a light source 11, a substrate 110, a heat dissipation member 111, and an adhesive 112. The light-emitting module 101 and the light-emitting module 100 are the same except for the positions of the four heat dissipation sections 200a, 200d, 200e, and 200h formed for dissipating heat from the Zener diode 32. Therefore, the positions of the four heat dissipation sections 200a, 200d, 200e, and 200h will be described here.

[0057] In the light-emitting module 101, the heat dissipation sections 200a and 200e are formed on the substrate 110 on the underside of the pad 210, rather than on the underside (-z direction side) of the Zener diode 32. Therefore, the heat dissipation sections 200a and 200e can dissipate the heat generated by the Zener diode 32 to the heat dissipation member 111 via the pad 210.

[0058] Furthermore, the heat dissipation sections 200d and 200h are formed on the substrate 110 on the underside of the pad 211, rather than on the underside (-z direction) of the Zener diode 32. Therefore, the heat dissipation sections 200d and 200h can dissipate the heat generated by the Zener diode 32 to the heat dissipation member 111 via the pad 211. Thus, the light-emitting module 101 can obtain the same effect as the light-emitting module 100.

[0059] In Figure 4, a Zener diode 32 is used as an example, but the heat dissipation area is not limited to a Zener diode 32. The heat dissipation area may be formed on the underside of the pad on which the component to be heated (for example, a MOS transistor 30) is mounted. Alternatively, the heat dissipation area may be formed only on the underside of the pad on which the component to be heated is mounted.

[0060] =====Summary===== The lighting circuit 10 and light-emitting modules 100 and 101 of this embodiment have been described above. In the lighting circuit 10 of Figure 1, when the power supply voltage Vb of the power supply line 22 becomes overvoltage, the transistor 33 connected to the Zener diode 32 turns on. As a result, the current flowing through the light source 11 and the MOS transistor 30 connected to the power supply line 22 becomes zero. This ensures that the light source 11 and the MOS transistor 30 are properly protected even when the power supply voltage Vb becomes overvoltage.

[0061] Furthermore, in the constant current circuit 31, the voltage Vc across resistor 41 is clamped by the threshold voltage of transistor 42. Therefore, the constant current circuit 31 can generate a constant current Ic determined by the resistance value of resistor 41 and the threshold voltage of transistor 42 with a simple configuration.

[0062] Furthermore, in the substrate 110 shown in Figure 2, the distance L1 between terminal 20 and Zener diode 32 is shorter than the distance L2 between terminal 20 and MOS transistor 30. This arrangement reduces the influence of parasitic elements between terminal 20 and Zener diode 32, allowing the Zener diode 32 to operate in a shorter time when the power supply voltage Vb of the power supply line 22 becomes overvoltage.

[0063] Furthermore, in the substrate 110 shown in Figure 2, the Zener diode 32 is positioned on the +x side of the light source 11, and the MOS transistor 30 is positioned on the -x side of the light source 11. Therefore, compared to, for example, the case where the Zener diode 32 and the MOS transistor 30 are positioned adjacent to each other on the substrate 110, heat can be dispersed.

[0064] Furthermore, as shown in Figure 3, the substrate 110 has a heat dissipation structure A (i.e., heat dissipation sections 200a to 200h) that dissipates the heat generated by the Zener diode 32 to the heat dissipation member 111. Therefore, the Zener diode 32 can be protected from heat.

[0065] Furthermore, as shown in Figure 3, the substrate 110 has a heat dissipation structure B (i.e., heat dissipation sections 202a to 202d) that dissipates the heat generated by the MOS transistor 30 to the heat dissipation member 111. In addition, the thermal conductivity of heat dissipation structure A (i.e., heat dissipation sections 200a to 200h) is higher than that of heat dissipation structure B (i.e., heat dissipation sections 202a to 202d). Therefore, in this embodiment, when an overvoltage is applied to the power line 22, the heat generated by the element with the greater heat output (in this case, the Zener diode 32) can be effectively dissipated.

[0066] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that equivalents thereof are included. [Explanation of Symbols]

[0067] 10 Lighting Circuit 11 Light source Terminals 20, 21 22 Power Lines 23 Grounding line 30 MOS transistors 31 Constant current circuit 32 Zener diodes 33,42 transistors 40, 41 resistors 80-82 Light-emitting elements 100,101 Light-emitting modules 110 circuit boards 111 Heat dissipation component 112 Adhesive 200a~200h,201a~201h,202a~202d Heat dissipation part 210, 211, 220, 221, 230, 231 pads R1~R4 resistance

Claims

1. A first transistor connected in series to a light source located between the power line and the ground line, A constant current circuit that generates a constant current flowing to the light source when the first transistor is turned on, and stops generating the constant current when the first transistor is turned off, A Zener diode having a cathode and an anode connected to the power line, A second transistor having a base connected to the anode, an emitter connected to the ground line, and a collector connected to the control electrode of the first transistor, A lighting circuit equipped with the following features.

2. A lighting circuit according to claim 1, The constant current circuit described above is A first resistor is provided between the power supply line and the control electrode of the first transistor, A second resistor is provided between the first transistor and the ground line, A third transistor having a base connected to the second resistor, an emitter, and a collector connected to the control electrode of the first transistor, A lighting circuit that includes this.

3. The lighting circuit according to claim 1, A substrate having a first surface on which the light source and the lighting circuit are mounted and which is provided with power terminals to which the power line is connected, Prepare, The first distance between the power supply terminal and the Zener diode is shorter than the second distance between the power supply terminal and the first transistor. Light-emitting module.

4. A light-emitting module according to claim 3, The Zener diode is positioned on the first side in the first direction from the position of the light source on the first surface. The first transistor is positioned on the second direction opposite to the first direction from the position of the light source on the first surface. Light-emitting module.

5. A lighting circuit according to any one of claims 1 to 4, A substrate having a first surface on which the light source and the lighting circuit are mounted, and a second surface opposite to the first surface, A heat dissipation member located on the second surface side of the substrate, Equipped with, The aforementioned substrate is The first heat dissipation structure has a heat dissipation structure that dissipates the heat generated by the Zener diode to the heat dissipation member. A light-emitting module equipped with the following features.

6. A light-emitting module according to claim 5, The aforementioned substrate is The device has a second heat dissipation structure that dissipates the heat generated by the first transistor to the heat dissipation member, The thermal conductivity of the first heat dissipation structure is higher than that of the second heat dissipation structure. Light-emitting module.

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