JP6595540B2 - Lighting circuit and signal device - Google Patents

Description

  The present invention relates to a lighting circuit that receives an AC voltage signal and emits light from an LED element unit in which a plurality of LED elements are connected in series, and a signal device using the lighting circuit.

  The signal device for road traffic also serves as a power supply line for supplying power to the signal lighting, and the signal line cable for transmitting the signal for lighting the signal lighting is set to 100 V corresponding to ON / OFF of the signal lighting. AC voltage is supplied / stopped. In this case, it is desirable to apply a DC voltage obtained by rectifying the 100 V AC voltage supplied to the signal line by the rectifying unit to the LED element unit in which a plurality of LED elements are connected in series. Compared with the case where a transformer is provided for each signal line to form an alternating voltage of several volts from a voltage of 100 volts and the rectified several volts of direct current voltage is applied to a plurality of LED elements connected in parallel, the power efficiency of signal illumination This is because it is advantageous for reducing the weight of the lighting circuit.

  By the way, when a high-voltage AC voltage is supplied / stopped to the signal line cable, when a high-voltage AC current flows through one of the parallel signal line cables, another AC current flows. A low voltage alternating current is induced in the cable of the signal line that is not. As a result, due to the DC voltage obtained by rectifying the induced AC voltage by the rectifying unit, a current flows through the signal illumination that should not emit light, and light is emitted weakly. This phenomenon is called induction lighting.

  In the induction lighting prevention circuit of Patent Document 1, when the voltage obtained by resistance-dividing the DC voltage rectified by the rectifying unit does not reach the Zener voltage of the Zener diode, the switching element connected in series with the LED element unit is not turned ON. A lighting circuit is configured. Such a lighting circuit will be described later with reference to FIG. For this reason, when a low-voltage AC voltage is induced in the signal line cable, the switching element is kept in the OFF state, and current does not easily flow to the LED element unit. In this way, induction lighting is prevented.

JP-A-10-250579

  In the induction lighting prevention circuit of Patent Document 1, when the voltage obtained by resistance-dividing the voltage rectified by the rectifying unit exceeds the Zener voltage of the Zener diode, the switching element of the transistor connected in series to the LED element unit may be turned on. . For this reason, when a short time high voltage or noise signal due to ON / OFF of high voltage or power supply noise is applied to the cable of the signal line, the switching element is turned ON and the signal illumination is erroneously emitted. In addition to the case where a low voltage alternating current is induced in a signal line cable, the present invention provides a lighting circuit that is unlikely to cause erroneous light emission of signal illumination even when a high voltage or noise signal is applied for a short time. It is intended to provide.

The lighting circuit of the present invention is a lighting circuit that receives an AC voltage signal and emits light from an LED element unit in which a plurality of LED elements are connected in series, and a rectifying unit that rectifies the AC voltage signal; a switching unit rectifier is turned ON / OFF a current flowing through the LED element portion by a voltage obtained by rectifying the voltage the rectifier is rectified partial pressure by a pair of resistance between the ground potential, of the pair of resistors between the resistance means for forming a connection point, the disposed between the connection point and the ground potential, a capacitor the resistor means is charged by the divided voltage, and the connection point and the control terminal of the switching unit disposed, and a first Zener diode element the potential difference between the control terminal and the connection point is oN the switching unit exceeds a first threshold voltage, between the ground potential said connection point Is location, the voltage charged in the capacitor, and a second zener diode to regulate the following second higher threshold voltage than the first threshold voltage, the switching unit is charged in the capacitor A transistor element in which a potential difference between the connection point and the control terminal exceeds the first threshold voltage and is directly controlled by a current flowing through the first Zener diode element when a voltage is equal to or lower than the second threshold voltage. It is characterized by that.
The lighting circuit of the present invention is a lighting circuit for a traffic device for road traffic that receives an AC voltage signal and emits light from an LED element unit in which a plurality of LED elements are connected in series. A rectifying unit that rectifies, a switching unit that turns ON / OFF a current flowing through the LED element unit by a voltage rectified by the rectifying unit, and a voltage that is rectified by the rectifying unit is divided by a pair of resistors between a ground potential And a resistance means for forming a connection point of the pair of resistors, a capacitor disposed between the connection point and a ground potential, and charged by a voltage divided by the resistance means, the connection point and the switching is arranged between the control terminal of parts, a first zener diode element the potential difference between the connection point and the control terminal is oN the switching unit exceeds a first threshold voltage, the contact Disposed between the point and the ground potential, wherein the voltage charged in the capacitor, and a second zener diode to regulate the following second higher threshold voltage than the first threshold voltage, the switching unit Is caused by a current flowing through the first Zener diode element with a potential difference between the connection point and the control terminal exceeding the first threshold voltage when a voltage charged in the capacitor is equal to or lower than the second threshold voltage. The transistor element is directly controlled.

  According to the lighting circuit of the present invention, in addition to the case where a low voltage alternating current is induced in the signal line cable, even when a high voltage or a noise signal is applied for a short time, erroneous light emission of the signal illumination occurs. A difficult lighting circuit can be provided.

1 is a circuit diagram of a signal device according to Embodiment 1. FIG. It is a circuit diagram of the lighting circuit of the signal apparatus of Example 1. It is a time chart of the example of operation of a trigger circuit. (A) is the input voltage of the rectifier, (b) is the rectified voltage of the rectifier, (c) is the charging voltage of the capacitor, (d) is the base current of the transistor, and (e) is the output current of the transistor. It is explanatory drawing of a structure of the lighting circuit of a comparative example. It is a circuit diagram of the lighting circuit of the signal apparatus of Example 2.

  The mode for carrying out the present invention will be described in detail by the following examples with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram of the signal device according to the first embodiment. FIG. 2 is a circuit diagram of a lighting circuit of the signal device. As shown in FIG. 1, the light source of each light of the traffic signal device 100 is a green LED element 14G, a yellow color (G), a yellow color (Y), and a red color (R). LED element portion 14Y and red LED element portion 14R are used. And LED element part 14G, 14Y, 14R is supplied with electric power from lighting circuit 10G, 10Y, 10R, respectively, and light-emits.

  The LED element portions 14G, 14Y, and 14R are common except for the light emission color of the LED element being used, and the lighting circuits 10G, 10Y, and 10R are the same as a whole. For this reason, below, the LED element part 14G and the lighting circuit 10G are demonstrated as the LED element part 14 and the lighting circuit 10, respectively, and the overlapping description regarding the lighting circuits 10Y and 10R is omitted.

(Lighting circuit)
The signal line SL that transmits a timing signal for lighting the LED element unit 14 also serves as a power supply line that supplies power to the LED element unit 14 for lighting. The control unit 110 controls light emission and extinction of each lamp of the signal device 100 by an AC voltage of 100 V output to the signal line SL. The control unit 110 starts supplying 100V AC voltage to the signal line SL at a timing when the LED element unit 14 is turned on, and stops supplying 100V AC voltage to the signal line SL at a timing when the LED element unit 14 is turned off. To do.

  The lighting circuit 10 rectifies the 100V AC voltage supplied to the signal line SL by the rectification unit 11. The lighting circuit 10 applies the DC voltage rectified by the rectifying unit 11 to a load in which the constant current unit 12, the LED element unit 14, and the switching unit 15 are connected in series to cause each lamp of the signal device 100 to emit light.

  Here, it is conceivable that a power transformer is provided in the lighting circuit 10 of each lamp, and a 100 V signal of the signal line SL is input to the primary side to output a low AC voltage of about 3 V from the secondary side. If a low AC voltage is rectified by a bridge diode to generate a DC voltage of about 5V, a large number of LED elements are connected in parallel, voltage is applied to all LED elements at the same timing, and all LEDs are output at the same timing. Application of voltage to the element can be stopped.

  However, if the lighting transformer 10 of each lamp is provided with a heavy and bulky power transformer, it is difficult to reduce the weight and size of the lighting circuit 10. The power efficiency of the lighting circuit 10 decreases due to the power transformer and the current regulating resistor, and the power required to obtain signal illumination increases.

  Therefore, in Example 1, the LED elements L1 to L7 and L8 to L14 are connected in series, and a DC voltage obtained by rectifying an AC voltage of 100 V is applied. Thereby, the number of parts of the lighting circuit 10 of each lamp is reduced, and miniaturization is facilitated. The LED element part 14 can be made to light-emit brightly with little power consumption. However, as described below, the LED elements L1 to L7 and L8 to L14 are connected in series and a relatively high voltage DC voltage is applied, which causes a problem of reduction in the lifetime of various elements. End up.

  As shown in FIG. 2, the rectifier 11 rectifies the 100V AC voltage supplied to the signal line SL into a DC voltage using a bridge diode B1. The constant current unit 12 regulates the current flowing to the LED element unit 14 to a predetermined constant current or less by a series circuit of constant current diodes D1, D2, and D3. The constant current diodes D1, D2, and D3 have a constant current value selected according to the brightness required in the LED element unit 14, and a maximum voltage selected according to the selected constant current value. For example, in Example 1, the constant current value is 15 mA and the maximum voltage is 50V.

  Since the constant current diodes D1, D2, and D3 are semiconductor elements to which a voltage is applied in the forward direction, they have a property that is vulnerable to surge voltage like the LED elements L1 to L7 and L8 to L14, and surge voltage exceeding the maximum voltage When is applied, normal semiconductor functions may be impaired. For this reason, three constant current diodes D1, D2, and D3 are connected in series to reduce a voltage burden per one in a transient state when the switching unit 15 is turned ON / OFF. The constant current diodes D1, D2, and D3 are connected in parallel to the Zener diodes E1, E2, and E3, respectively, and the surge voltage transiently applied to the constant current diodes D1, D2, and D3 is applied to the Zener diodes E1, E2, and so on. Bypass to E3. The Zener diodes E1, E2, and E3 bypass the surge voltage so that the voltage rectified by the bridge diode B1 does not concentrate on one of the constant current diodes D1, D2, and D3.

  Here, the reason why the parallel circuit of the constant current diodes D1, D2, D3 and the Zener diodes E1, E2, E3 is divided into three blocks and connected in series is to cope with the downsizing of the lighting circuit 10, This is because the power consumption, withstand voltage, and heat source dispersion are taken into consideration. Therefore, it is possible to deal with a single constant current diode D1 with respect to a lighting circuit having a specification with a sufficient mounting area and heat radiation design. Another reason is that, depending on the specifications of the lighting circuit, there are cases where only one block and only two blocks are used while sharing circuit elements. For example, when only two blocks are used, it is possible to cope with the problem by replacing the constant current diode D3 and the Zener diode E3 with jumper resistors, respectively.

  The LED element section 14 causes a constant current of 15 mA regulated by the constant current section 12 to flow through a circuit in which the seven LED elements L1 to L7 and the seven LED elements L8 to L14 are connected in series. L1 to L7 and L8 to L14 are caused to emit light.

  A Zener diode E4 is connected in parallel with the seven LED elements L1 to L7, and a surge voltage transiently applied to the LED elements L1 to L7 is bypassed to the Zener diode E4 to protect the LED elements L1 to L7. ing. Further, a Zener diode E5 is connected in parallel with the seven LED elements L8 to L14, and a surge voltage transiently applied to the LED elements L8 to L14 is bypassed to the Zener diode E5, so that the LED elements L8 to L14 are connected. Protect. The reason why the Zener diodes E4 and E5 are provided for each of the seven LED elements L1 to L7 and L8 to L14 is that the number of LED elements for each Zener diode is adjusted in accordance with the protection voltage of the Zener diodes E4 and E5. . For example, in Example 1, since the protection voltage of the Zener diodes E4 and E5 is 24V, the number of the LED elements L1 to L7 and L8 to L14 is seven. Generally, a Zener diode with a high protection voltage is difficult to obtain and expensive, but if there is a Zener diode with a protection voltage of 48 V, one Zener diode is connected in parallel to the entire LED elements L1 to L7 and L8 to L14. You may connect to and protect.

  The switching unit 15 includes a transistor T1 that is an NPN transistor. The transistor T1 turns on and off a constant current of 15 mA flowing through the LED element unit 14 to light / light off the LED elements L1 to L7 and L8 to L14.

  The transistor T1 receives the trigger signal output from the trigger circuit 13 as a base and conducts between the collector and the emitter, thereby converting the voltage of the full-wave rectified waveform obtained by rectifying the signal voltage input to the lighting circuit 10 to the LED element. Applied to the unit 14. The transistor T1 prevents the surge voltage from being applied to the LED elements L1 to L7 and L8 to L14 by changing the voltage applied to the LED elements L1 to L7 and L8 to L14 in an analog manner between ON and OFF. To do.

(Trigger circuit)
Is an example of a resistance means the resistance R1, R2 is the voltage V11 that bridge diode B1 of the rectifier unit 11 is rectified partial pressure, to form the connection point of the resistors R1, R2. Capacitor C1, which is an example of a capacitor, is charged with a voltage divided by resistors R1 and R2. The first Zener diode ZD1, which is an example of the first Zener diode element, is disposed between the capacitor C1 and the transistor T1. The first Zener diode ZD1 turns on the transistor T1 when the voltage V13 charged in the capacitor C1 exceeds the first threshold voltage VZ1 that is the Zener voltage. The first Zener diode ZD1 turns off the transistor T1 when the voltage V13 charged in the capacitor C1 becomes equal to or lower than the Zener voltage.

  The trigger circuit 13 divides the voltage V11 rectified by the rectification unit 11 with resistors R1 and R2, and charges the capacitor C1 with the divided voltage. When the voltage V13 charged in the capacitor C1 exceeds the Zener voltage of the first Zener diode ZD1, the charge charged in the capacitor C1 flows into the base of the transistor T1 as a current. As a result, the transistor T1 is turned on, and a current flows through the LED elements L1 to L7 and L8 to L14 to emit light.

  The trigger signal output from the trigger circuit 13 to the transistor T1 is not output at all until the voltage V13 charged in the capacitor C1 reaches the Zener voltage of the first Zener diode ZD1. When the voltage V13 charged in the capacitor C1 reaches the Zener voltage of the first Zener diode ZD1, supply of the base current is started immediately to the base of the transistor T1, and the base current is gradually increased.

  For this reason, the base current that flows into the base of the transistor T1 as a trigger signal has its noise removed by the capacitor C1, and rises smoothly from 0 with a slope. For this reason, the transistor T1 operates in an analog manner to increase the emitter current smoothly, and gradually increase the current flowing through the LED elements L1 to L7 and L8 to L14 to 15 mA. Thereby, it is suppressed that a transient surge voltage is applied to the LED elements L1 to L7, L8 to L14, and the constant current diodes D1, D2, and D3 due to ON / OFF of the AC voltage.

  Further, when the AC voltage is turned OFF and the output of the bridge diode B1 becomes 0V, the electric charge of the capacitor C1 is quickly discharged through the resistor R2. For this reason, even when a large surge voltage is generated in the signal line SL immediately after the AC voltage is turned off, the surge voltage is absorbed by the capacitor C1, and the OFF state of the transistor T1 is stably maintained.

  The second Zener diode ZD2, which is an example of the second Zener diode element, regulates the voltage charged in the capacitor C1 to be equal to or lower than the second threshold voltage VZ2 that is the Zener voltage. When the capacitor C1 exceeds the second threshold voltage VZ2, the charge exceeding the second threshold voltage charged in the capacitor C1 is discharged to the ground potential as the Zener current of the second Zener diode ZD2.

  For this reason, even if high-frequency noise or spike voltage is included in the voltage V11 rectified by the bridge diode B1 due to ON / OFF of the AC voltage, the voltage V13 charged in the capacitor C1 is affected by these effects. Absent. Therefore, even if the voltage V11 rectified by the bridge diode B1 includes high-frequency noise or spike voltage, the base current flowing into the base of the transistor T1 is kept stable, and the transistor T1 generates chattering and surge voltage. Without increasing the emitter current smoothly. Thereby, it is suppressed that a transient surge voltage is applied to the LED elements L1 to L7, L8 to L14, and the constant current diodes D1, D2, and D3 due to ON / OFF of the AC voltage.

The standard of each element used was selected as follows.
1. LED elements L1 to L14: Maximum current 30 mA
2. First Zener diode ZD1: Zener voltage 7.5V, capacity 200mW
3. Second Zener Diode ZD2: Zener voltage 12V, capacity 200mW
4). Zener diodes E1, E2, E3: Zener voltage 24V, maximum current 3A
5). Constant current diodes D1, D2, D3: Constant current 15mA, maximum voltage 50V

(Example of trigger circuit operation)
FIG. 3 is a time chart of an operation example of the trigger circuit. 3, (a) is the input voltage of the rectifier unit, (b) is the rectified voltage of the rectifier unit, (c) is the capacitor charging voltage, (d) is the base current of the transistor, and (e) is the output current of the transistor. It is.

  As shown in (a) of FIG. 3, the control unit 110 outputs a normal signal voltage Vs from the time t <b> 1 and inputs it to the rectifying unit 11. At this time, as shown in FIG. 3B, the bridge diode B1 outputs a voltage Vt having a full-wave rectified waveform from time t1. As shown in FIG. 3C, the capacitor C1 is charged by the voltage divided by the resistors R1 and R2, and the charging voltage Vu increases with a slope from time t1.

  When the charging voltage Vu of the capacitor C1 reaches the first threshold voltage VZ1 at time t2, as shown in FIG. 3D, the base current flowing from the time t2 to the base of the transistor T1 through the first Zener diode ZD2 increases as shown in FIG. To do. Then, when the base voltage of the transistor T1 reaches the threshold voltage of the transistor T1 at time t3, current starts to flow between the collector / emitter of the transistor T1, as shown in FIG. A continuous base current is continuously supplied, and the collector / emitter is kept in a conductive state.

  Thereafter, when the charging voltage Vu of the capacitor C1 reaches the second threshold voltage VZ2 at time t4, as shown in FIG. 3D, the base current flowing into the base of the transistor T1 becomes constant, and (e ), It is avoided that an excessive base current flows into the transistor T1 to impair the life of the transistor T1.

(Lightly lit)
As shown in FIG. 1, in the signal device 100, since the voltage of 100V is applied / stopped to the parallel signal lines SL of the respective lamps, the LEDs that are turned off by electromagnetic induction between the parallel signal lines SL of the respective lamps. There is a possibility that the element unit 14 is lit weakly. That is, an induced voltage is generated in the signal line SL of the LED element unit 14 in the extinguished state by electrostatic coupling between the parallel cables of the signal line SL connecting the control unit 110 and the lighting circuit 10. And the induced voltage which generate | occur | produced is rectified by the rectification | straightening part 11, a weak voltage generate | occur | produces, a weak direct current will flow into the LED element part 14 of a light extinction state, and it will light. The electrostatic coupling between the parallel cables of the signal line SL increases in proportion to the parallel length, and as the electrostatic coupling increases, the induced voltage increases, and the LED element that is turned off is weakly lit. Become prominent.

  As shown in FIG. 3A, a voltage of 100 V was applied to the cable of the signal line SL at time T5. At this time, an induced voltage is generated in the cable of another signal line SL connecting the control unit 110 and the lighting circuit 10, and the voltage obtained by rectifying the induced voltage is charged in the capacitor C1 as shown in FIG. Is done. However, in the first embodiment, as shown in FIG. 3C, unless the charging voltage Vu of the capacitor C1 reaches the first threshold voltage VZ1, which is the Zener voltage of the first Zener diode ZD1, (e ), The transistor T1 remains in the OFF state, and no current flows through the LED elements L1 to L14. For this reason, the LED elements L1 to L14 are not easily lit.

(Spike voltage)
As shown in FIG. 1, in the signal device 100, spike noise may occur in the signal line SL as the voltage is switched on / off in the control unit 110 or due to power supply noise such as lightning. That is, when a large spike noise is generated in the signal line SL in the OFF state that connects between the control unit 110 and the lighting circuit 10, the rectification unit 11 rectifies and the trigger circuit 13 also operates to turn off the LED element unit 14 in the off state. Current may flow through

  As shown in FIG. 3A, spike noise occurred in the cable of the signal line SL at time T6. At this time, as shown in FIG. 3C, a voltage obtained by rectifying the induced voltage is charged in the capacitor C1. However, in the first embodiment, as shown in FIG. 3C, unless the charging voltage Vu of the capacitor C1 reaches the first threshold voltage VZ1, which is the Zener voltage of the first Zener diode ZD1, (e ), The transistor T1 remains in the OFF state, and no current flows through the LED elements L1 to L14. For this reason, even if spike noise occurs, the LED elements L1 to L14 are unlikely to turn on erroneously.

(Transient high voltage)
In the signal device 100, a high DC voltage is applied to the series circuit of the LED elements L <b> 1 to L <b> 14, the constant current diodes D <b> 1 to D <b> 3, and the switching unit 15. In such a case, when the switching unit 15 is turned on, one of the LED elements L1 to L14 and the constant current diodes D1 to D3 may be damaged. Due to variations in the characteristics of the LED elements L1 to L14 and the constant current diodes D1 to D3, a large voltage is transiently applied to one of the diode elements connected in the forward direction when the switching unit 15 is turned on. This is because an overcurrent may flow.

  However, in the signal device 100, when the Zener diodes E4 and E5 are disposed for the LED elements L1 to L14, and the Zener diodes E1 to E3 are disposed for the constant current diodes D1 to D3, a large voltage is applied. The overcurrent is bypassed to the Zener diode. For this reason, it is avoided that an overcurrent flows through one of the LED elements L1 to L14 and the constant current diodes D1 to D3 and is damaged. Therefore, in the first embodiment, the signal device 100 is provided in which one of the plurality of diode elements connected in series is less likely to be damaged when the switching unit 15 is turned on.

(Comparative example)
FIG. 4 is an explanatory diagram of a configuration of a lighting circuit of a comparative example. As shown in FIG. 4, in the lighting circuit 10H of the comparative example, the first Zener diode ZD1 of the trigger circuit 13 is disposed between the connection line of the resistors R1 and R2 and the capacitor C2. Further, the second Zener diode ZD2 that regulates the charging voltage Vu of the capacitor C2 is not provided. The switching unit 15 employs a MOSFET transistor F1 instead of an NPN transistor. Since the other configuration is the same as that of the first embodiment, a part of the configuration is omitted in FIG. 4, the same reference numerals as those in FIG. 2 are used, and the description of the overlapping portions is omitted.

  The trigger circuit 13H in the lighting circuit 10H of the comparative example divides the voltage rectified by the rectifier 11 by resistors R1 and R2. The capacitor C1 charges the voltage divided by the resistors R1 and R2 through the first Zener diode ZD1. The first Zener diode ZD1 charges the capacitor C1 when the voltage divided by the resistors R1 and R2 exceeds the first threshold voltage VZ1 that is the Zener voltage. Then, the MOSFET transistor F1 is operated by the voltage applied to the capacitor C1, and the LED element portion 14H is caused to emit light.

  For this reason, in the lighting circuit 10H of the comparative example, when the voltage divided by the resistors R1 and R2 exceeds the first threshold voltage VZ1, the capacitor C1 is charged. When the charging voltage of the capacitor C1 becomes equal to or higher than the threshold voltage of the transistor F1 due to charging, the transistor F1 is activated and immediately becomes conductive, and the LED element unit 14H may emit light. For this reason, compared with the lighting circuit 10 of Example 1 in which a current does not flow through the LED element unit 14 until the charging voltage Vu of the capacitor C1 becomes equal to or higher than the first threshold voltage VZ1, the operation is likely to be unstable.

  In the lighting circuit 10H of the comparative example, the capacitor C1 is not charged at all until the voltage divided by the resistors R1 and R2 of the trigger circuit 13H reaches the first threshold voltage VZ1. For this reason, when the capacity of the capacitor C1 is large, the timing at which the transistor F1 operates is delayed, and the delay in the light emission timing of the LED element portion 14H becomes conspicuous.

  On the other hand, in the lighting circuit 10H of the comparative example, if the capacitance of the capacitor C1 is reduced in order to eliminate the delay in the light emission timing of the LED element unit 14H, the capacitor C1 is not connected when high voltage spike noise enters the signal line SL. It will be easily charged and LED element part 14H will light-emit easily. In the case of spike noise, since the voltage itself rectified by the rectifying unit 11 becomes high, the LED element unit 14H emits light strongly and becomes conspicuous.

(Effect of Example 1)
In the first embodiment, the lighting circuit 10 receives an AC voltage signal and causes a plurality of LED elements connected in series with the display illumination to emit light with the power of the AC voltage signal. For this reason, the number of parts of the lighting circuit 10 is reduced, and miniaturization and weight reduction are facilitated. In addition, bright display illumination can be performed with less power.

  In the first embodiment, the switching unit 15 turns ON / OFF the current flowing through the plurality of LED elements by the voltage rectified by the rectifying unit 11. The first Zener diode ZD1 turns on the switching unit 15 when the voltage charged in the capacitor C1 exceeds the first threshold voltage VZ1. For this reason, in the OFF state, the surge voltage rectified by the rectifying unit 11 is absorbed by the capacitor C1, the OFF state is stably maintained, and the surge voltage rectified by the rectifying unit 11 in the OFF state is applied to the plurality of LED elements. It has become difficult. Therefore, when the switching unit 15 is turned on, one of the plurality of LED elements 1 to 14 connected in series is rarely damaged.

  In the first embodiment, the second Zener diode ZD2 regulates the voltage charged in the capacitor C1 to be equal to or lower than the second threshold voltage VZ2 higher than the first threshold voltage VZ1. For this reason, the part exceeding the second threshold voltage VZ2 of the surge voltage rectified by the rectifying unit 11 in the ON state hardly affects the switching unit 15. Therefore, when the switching unit 15 is turned on, one of the plurality of LED elements 1 to 14 connected in series is rarely damaged.

  In the first embodiment, the switching unit 15 is a transistor element whose base current is controlled by a current flowing through the first Zener diode ZD1. For this reason, the resistance is changed in an analog manner between the ON state and the OFF state, the change in the voltage applied to the plurality of LED elements L1 to L14 is alleviated, and one LED element whose ON is delayed is increased. Avoid applying voltage. Therefore, when the switching unit 15 is turned on, one of the plurality of LED elements 1 to 14 connected in series is rarely damaged.

  In Example 1, the constant current unit 12 is arranged in series with respect to the plurality of LED elements L1 to L14, and the current flowing through the plurality of LED elements L1 to L14 using the constant current diodes D1, D2, and D3 is constant current. To regulate. For this reason, even if a surge voltage is generated in the AC voltage rectified by the rectifying unit 11, the current flowing through the LED elements L1 to L14 is maintained constant, and the brightness of the signal illumination does not change.

  In Example 1, the constant current unit 12 has a plurality of constant current diodes D1, D2, and D3 connected in series. And each constant current diode D1, D2, D3 is bypassed by Zener diode E1, E2, E3 which has a Zener voltage smaller than the maximum voltage specification. For this reason, even if voltages higher than the individual maximum voltages of the constant current diodes D1, D2, and D3 are applied to the LED elements L1 to L14, the constant current diodes D1, D2, and D3 lose their normal semiconductor functions. Absent. Therefore, when the switching unit 15 is turned on, one of the plurality of LED elements 1 to 14 connected in series is rarely damaged.

  In the first embodiment, ON / OFF of the transistor T1 of the switching unit 15 corresponds to binary values of conduction and interruption. On the other hand, in the second embodiment, the conduction state when the transistor T1 is ON is variable, and the transistor T1 of the switching unit 15 is also used for current control of the plurality of LED elements L1 to L14.

  FIG. 5 is a circuit diagram of a lighting circuit of the signal device according to the second embodiment. As illustrated in FIG. 5, the lighting circuit 10 </ b> A according to the second embodiment adjusts the current flowing through the LED elements L <b> 1 to L <b> 14 by the current regulating unit 12 </ b> A and the transistor T <b> 1. Since the other configuration is the same as that of the lighting circuit 10 of the first embodiment, in FIG. 5, the same reference numerals as those in FIG.

  The current regulating unit 12A regulates the current flowing through the LED elements L1 to L14 by the resistor R8 provided with the heat sink 18. The switching unit 15 functions as a resistor that regulates the current flowing through the LED elements L1 to L14 by providing the heat sink 19 in the transistor T1 and adjusting the base current. The variable resistor R6 that supplies the base current to the transistor T1 has a resistance value so that a current of 15 mA flows through the series circuit of the LED elements L1 to L14 in a state where an AC voltage of 100 V is applied to the signal line SL in advance. It has been adjusted.

  Thereby, the voltage rectified by the rectifying unit 11 is applied to the series circuit of the resistor R8, the LED elements L1 to L14, and the transistor T1, and the resistor R8 and the transistor T1 so that a current of 15 mA flows through the LED elements L1 to L14. The voltage drop is set.

  Therefore, the switching unit 15 is not limited to a simple conduction / cutoff element, and may be an analog element that sets the operating current of the LED elements L1 to L14.

(Other embodiments)
The lighting circuit of the present invention is not limited to the specific configuration and application described in the first and second embodiments. Another embodiment in which a part or all of the configurations of the first and second embodiments are replaced with an equivalent configuration is also possible.

  For example, in the first embodiment, the lighting circuit of the signal device for road traffic has been described. However, the lighting circuit of the first embodiment can also be implemented as a lighting circuit for indicator lights such as switchboards, elevators and warning lights. Furthermore, the lighting circuit of the first embodiment can be implemented as a lighting circuit for LED lamp light sources for lighting for home use or business use, and other LED lamp light sources for display.

  In the first embodiment, the embodiment in which the currents flowing through the LED elements L1 to L14 are regulated by the constant current diodes D1, D2, and D3 has been described. However, as described in the second embodiment, the current flowing through the LED elements L1 to L14 may be regulated using a fixed resistor or a transistor. A general constant current circuit that does not use a constant current diode may be substituted.

  In the first embodiment, the switching unit 15 is switched from ON to OFF with the first threshold voltage VZ1 of the first Zener diode ZD1, and is similarly switched from OFF to ON with the first threshold voltage VZ1. However, the switching unit 15 may be switched from ON to OFF with the first threshold voltage VZ1, while the switching unit 15 may be switched from OFF to ON with a threshold voltage slightly lower than the first threshold voltage VZ1. By giving the switching unit 15 hysteresis characteristics, the operation of the switching unit 15 can be further stabilized.

  Since the present invention is configured as described above, particularly in an electronic apparatus that performs signal illumination such as a traffic light, the LED element emits light with high efficiency without using a power transformer, and stable signal illumination with less erroneous light emission. Can be obtained.

10 (10G, 10Y, 10R) Lighting circuit 10A Lighting circuit 11 of Example 2 Rectifier (rectifier)
12 Constant current section (constant current section)
12A Current regulating unit 13 Trigger circuit 14 LED element unit 15 Switching unit 100 Signal device 110 Control unit B1 Bridge diode C1 Capacitor (capacitor)
D1, D2, D3 Constant current diode (constant current diode)
E1, E2, E3 Zener diodes E4, E5, Zener diodes L1-L7 LED elements (LED elements)
L8 ~ L14 LED element (LED element)
R1, R2 resistance (resistance means)
R3, R4, R5 Resistance T1 Transistor (switching element)
ZD1 first Zener diode (first Zener diode element)
ZD2 second Zener diode (second Zener diode element)

Claims (6)

A lighting circuit that receives an AC voltage signal and emits light from an LED element unit in which a plurality of LED elements are connected in series,
A rectifying unit for rectifying the AC voltage signal;
A switching unit that turns ON / OFF the current flowing through the LED element unit by the voltage rectified by the rectifying unit;
A resistance means to the partial pressure by a pair of resistors, to form the connection point of the pair of resistors between the ground potential voltage the rectifier is rectified,
A capacitor disposed between the connection point and a ground potential and charged by a voltage divided by the resistance means;
Is arranged between the control terminal of the switching unit and the connection point, a first zener diode element the potential difference between the control terminal and the connection point is ON the switching unit exceeds a first threshold voltage,
A second Zener diode element disposed between the connection point and a ground potential and regulating a voltage charged in the capacitor to a second threshold voltage higher than the first threshold voltage;
In the switching unit, a potential difference between the connection point and the control terminal exceeds the first threshold voltage in a range where a voltage charged in the capacitor is equal to or lower than the second threshold voltage, and the first Zener diode element is A transistor element directly controlled by a flowing current;
A lighting circuit characterized by that. A lighting circuit for a road traffic signal device that receives an AC voltage signal and emits light from an LED element unit in which a plurality of LED elements are connected in series.
A rectifying unit for rectifying the AC voltage signal;
A switching unit that turns ON / OFF the current flowing through the LED element unit by the voltage rectified by the rectifying unit;
A resistance means to the partial pressure by a pair of resistors, to form the connection point of the pair of resistors between the ground potential voltage the rectifier is rectified,
A capacitor disposed between the connection point and a ground potential and charged by a voltage divided by the resistance means;
Is arranged between the control terminal of the switching unit and the connection point, a first zener diode element the potential difference between the control terminal and the connection point is ON the switching unit exceeds a first threshold voltage,
A second Zener diode element disposed between the connection point and a ground potential and regulating a voltage charged in the capacitor to a second threshold voltage higher than the first threshold voltage;
In the switching unit, a potential difference between the connection point and the control terminal exceeds the first threshold voltage when the voltage charged in the capacitor is equal to or lower than the second threshold voltage, and the first Zener diode element is turned on. A transistor element directly controlled by a flowing current;
A lighting circuit characterized by that.

The switching unit is a bipolar transistor element whose base current is controlled by a current flowing through the first Zener diode element.
The lighting circuit according to claim 1, wherein: A constant current unit that is arranged in series with the plurality of LED elements and regulates the current flowing through the plurality of LED elements to a constant current using a constant current diode,
The lighting circuit according to claim 3. The constant current unit includes a plurality of constant current diodes connected in series, and each constant current diode is bypassed by a Zener diode having a Zener voltage smaller than the maximum voltage standard.
The lighting circuit according to claim 4. It has a lighting circuit given in any 1 paragraph among Claims 1-5.
A signal device.

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