JP2012003865A - Led lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device which can prevent an excess electric current from flowing through an LED at the time of turning-on control for the LED.SOLUTION: A control circuit 17, during turning-on control for an LED 22, controls a lighting circuit 20 in response to a detection signal from an electric current detection part 23 so that the LED 22 has prescribed brightness, while controlling an output voltage from a DC/DC converter 25 in response to a detection signal from a voltage detection part 24. And, at the time of turning-off control for the LED 22, the control circuit 17 controls the DC/DC converter 25 so that an applied voltage to the LED 22 or the output voltage from the DC-to-DC converter 25 is equal to the voltage at the time of the turning-on control for the LED 22.

Description

  Embodiments of the present invention relate to an LED lighting device for lighting an LED lamp used in a marker lamp such as an airport.

  A marker lamp used in an airport or the like is energized by being connected in series to an output terminal of an AC constant current power source. In addition, in order to maintain a good appearance of the sign even if the ambient brightness changes, the sign lamp can be changed to a predetermined lamp by switching the output current of the AC constant current power source according to the ambient brightness. Controlled to operate at luminous intensity ratio. For example, a switching tap for output current is provided in an AC constant current power supply so that the luminous intensity ratio can be selected as desired from five levels of 100%, 25%, 5%, 1% and 0.2%. Has been.

  Some lamps use halogen bulbs and LEDs as the light source, and those using LEDs as the lamp light source use an AC constant current power supply that outputs current that is the luminous intensity ratio of the already installed halogen bulb. I use it as it is.

  Since the required current differs between the halogen bulb and the LED even at the same luminous intensity, an indicator using the LED as the light source while leaving the AC constant current power source that outputs the current that is the luminous intensity ratio of the already installed halogen bulb. In order to apply to a lamp, it is necessary to convert the current of the luminous intensity ratio of the halogen bulb into the current of the luminous intensity ratio of the LED.

  The light intensity ratio switching tap in the AC constant current power supply is set so that a predetermined light intensity can be obtained when the output current of a marker lamp equipped with a halogen bulb is energized. It is as follows. On the other hand, in the case of an LED, the current required to obtain the same luminous intensity is as shown in the right column of Table 1.

[Table 1]
AC constant current power supply Halogen bulb (current) LED (current)
Tap 5 (luminous intensity 100%) 100.0% (6.6A) 100% (350mA)
Tap 4 (luminous intensity 25%) 78.9% 25%
Tap 3 (luminance 5%) 62.1% 5%
Tap 2 (Luminance 1%) 51.5% 1%
Tap 1 (luminous intensity 0.2%) 42.4% 0.2%
Thus, since the required current differs between the halogen bulb and the LED even at the same luminous intensity, for example, when the current of the AC constant current power source is 78.9%, the light source is the LED. Must be converted to 25% current, 52.1% for 62.1%, 1% for 51.5%, and 0.2% for 42.4%. . For this reason, in a marker lamp that uses an LED fed from an existing AC constant current power source as a light source, the light intensity ratio-current characteristics are converted, or the LED is controlled to be turned on (including dimming control, and so on). It has an LED lighting device.

  As an LED lighting device for a marker lamp using an LED as a light source, there is one equipped with a load adjustment circuit that works to compensate for a difference between a current switching characteristic of an AC constant current power supply and a load current characteristic of the LED marker lamp ( For example, see Patent Document 1). This LED lighting device forms a circuit that bypasses the input current and adjusts the current supplied to the LED to a constant, and the duty control (PWM) so that the current flowing through the LED becomes a current corresponding to the luminous intensity ratio. Switch element Q2 to be controlled).

JP 2006-139755 A

  However, in Patent Document 1, the switch element Q1 is turned on when the LED of the LED lamp is controlled to be turned off, and the current from the AC constant current power supply is bypassed by the switch element Q1, but there is a smoothing circuit (capacitor). Therefore, the supply current to the LED does not immediately become zero, and it takes time until the LED is turned off. In order to improve the responsiveness of turning on / off the LED, turning on / off control is performed by the switch element Q2. However, when the switch element Q2 is turned off, the output side of the LED lighting device is in a no-load state. Therefore, the output side of the LED lighting device has a high voltage. Since the LED lighting device has an overvoltage protection function, the overvoltage protection function operates, and the output voltage (circuit voltage) of the LED lighting device becomes a voltage limited by the overvoltage protection function. This limiting voltage is a voltage value higher than the normal lighting voltage.

  Therefore, when the LED is turned off, the voltage value is maintained higher than the normal lighting voltage. When lighting control is next performed in this state, an overcurrent flows through the LED instantaneously. If the type of LED lamp is fixed and the number of LEDs to be lit is constant, it is possible to set the limit voltage of overvoltage protection to a reasonable voltage value. However, multiple types of LED lamps are lit. When the number of LEDs to be changed changes, the limit voltage must be set larger.

  Therefore, an LED lighting device that can prevent an overcurrent from flowing to the LED during the lighting control of the LED is provided.

  According to an embodiment of the present invention, a rectifier circuit that rectifies an AC power supply voltage; a DC / DC converter that varies an output voltage supplied to an LED by inputting an output voltage of the rectifier circuit; A lighting circuit that controls the current supplied from the DC / DC converter to the LED according to the current; a current detector that detects the LED current; and a voltage that detects the voltage applied to the LED or the output voltage of the DC / DC converter A detection unit; during LED lighting control, the lighting circuit is controlled in accordance with a detection signal of the current detection unit so that the brightness of the LED becomes a predetermined brightness, the LED current is controlled, and the voltage detection unit The output voltage of the DC / DC converter is controlled according to the detection signal of the LED, and when the LED is turned off, the voltage applied to the LED or the output voltage of the DC / DC converter becomes the voltage during the LED lighting control. It is provided with; and a control circuit for controlling the urchin DC-DC converter.

  ADVANTAGE OF THE INVENTION According to this invention, it can prevent that overcurrent flows into LED at the time of lighting control of LED.

The circuit diagram of the LED lighting device which concerns on embodiment of this invention. The operation | movement waveform diagram which shows an example of operation | movement of the LED lighting device which concerns on embodiment of this invention. The operation | movement waveform diagram which shows another example of operation | movement of the LED lighting device which concerns on embodiment of this invention. The operation | movement waveform diagram which shows another example of operation | movement of the LED lighting device which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below. FIG. 1 is a configuration diagram of an LED lighting device according to an embodiment of the present invention. In the following description, a case where the AC power source is the AC constant current power source 11 in which the output current includes information on the lighting control / extinguishing control command will be described. However, the AC power source includes information on the lighting control / extinguishing control command. The information on the lighting control / extinguishing control command may be given by a manual, a remote control, a sensor output, or the like.

  The AC constant current power source 11 has a plurality of switching taps, and outputs a plurality of stages of output current that have been converted to a constant current by switching the switching taps, and the output current can be switched by the switching tap according to the luminous intensity ratio. It is configured to be possible.

  The output current changes according to the stage of the switching tap, and the predetermined luminous intensity ratio changes. The luminous intensity ratio is usually adjusted to the specific luminous intensity-specific current characteristics of the halogen bulb (incandescent bulb) shown in the middle column of Table 1. ing. Therefore, the predetermined luminous intensity ratio is expressed by the output current of the AC constant current power supply 11 by switching the switching tap.

  An output current according to a predetermined luminous intensity ratio supplied from the AC constant current power supply 11 is input to the rectifier circuit 14 of the LED lighting device 13 via a saturable insulation transformer, for example, a rubber-covered insulation transformer 12. At the same time, it is supplied to the primary winding of the insulation current transformer 15 and input to the input current detection circuit 16 via the insulation current transformer 15.

  The input current detection circuit 16 inputs a current supplied from the AC constant current power supply 11 via the insulation current transformer 15 and detects an output current from the AC constant current power supply 11. The luminous intensity ratio is calculated from the value of the output current from the AC constant current power supply 11 detected by the input current detection circuit 16 and input to the control circuit 17.

  On the other hand, the current rectified by the rectifier circuit 14 is input to the DC / DC converter 25. The DC / DC converter 25 varies the output voltage supplied to the LED, and includes a load adjustment circuit 18 and a smoothing circuit 19. The output of the direct current / direct current converter 25 is supplied to the LED lamp body 21 via the lighting circuit 20 constituted by a PWM controlled switching device or the like. The LED lamp 21 includes an LED 22 that is a light source. When a plurality of LEDs 22 are used, the plurality of LEDs 22 are connected in series. The number of the LEDs 22 can be changed according to the type and application of the LED lamp body 21.

  The control circuit 17 controls the load adjustment circuit 18 and the lighting circuit 20 of the DC / DC converter 25. The control circuit 17 receives the current detected by the current detection unit 23 and the voltage detected by the voltage detection unit 24. The current detected by the current detector 23 is a current supplied to the LED 22, and the voltage detected by the voltage detector 24 is a voltage applied to the LED 22. In this embodiment, the output voltage of the smoothing circuit 19 is also used. is there. The control circuit 17 sets a voltage value at which a predetermined current should flow through the LED 22 in accordance with the detection signal from the current detection unit 23. That is, in the present embodiment, the output voltage value of the smoothing circuit 19 of the DC / DC converter 25 is set so that the peak value of the LED current that is PWM controlled becomes a predetermined value. Thereby, it can respond also to the LED lamp body 21 from which the number of LED22 differs.

  The control circuit 17 forms a power supply circuit to be applied to the LED 22 by the load adjustment circuit 18 of the DC / DC converter 25 during the lighting control of the LED 22 of the LED lamp body 21. At that time, when the current or voltage applied to the LED 22 exceeds a predetermined value, the load adjustment circuit 18 forms a bypass circuit that bypasses the input current to the power supply circuit, and adjusts the current flowing through the bypass circuit, During the lighting control of the LED 22, the current or voltage applied to the LED 22 is adjusted to be constant.

  Further, the power supply circuit formed by the load adjustment circuit 18 so that the brightness of the LED 22 becomes a predetermined brightness corresponding to a current of a predetermined luminous intensity ratio supplied from the AC constant current power supply 11 by the lighting circuit 20. The LED 22 is turned on by adjusting the current from.

  On the other hand, the control circuit 17 cuts off the supply of the current supplied from the AC constant current power supply 11 to the LED 22 by the lighting circuit 20 during the turning-off control of the LED 22 of the LED lamp body 21. Further, the load adjustment circuit 18 controls the circuit voltage of the power supply circuit so as to be the circuit voltage value when the LED 22 is lit. As a result, even if the lighting circuit 20 cuts off the supply of current supplied from the AC constant current power supply 11 to the LED 22 and the load LED 22 becomes open and no load is applied, the same voltage value as the normal lighting voltage is obtained. Retained. Therefore, it is possible to prevent an overcurrent from flowing to the LED 22 when the LED 22 is turned on from the turn-off control state of the LED 22.

  In the above description, the case where the DC / DC converter 25 includes the load adjustment circuit 18 and the smoothing circuit 19 has been described. Any device can be used as long as the voltage can be varied.

  FIG. 2 is an operation waveform diagram showing an example of the operation of the LED lighting device according to the embodiment of the present invention. Now, it is assumed that the AC constant current power supply 11 is started up at time t0 and a current is input to the LED lighting device 13 from the AC constant current power supply 11. Then, since the AC constant current power supply 11 is a current source, an attempt is made to flow current between the lighting circuit 20 and the LED lamp body 21 via the rectifier circuit 14, the load adjustment circuit 18 and the smoothing circuit 19. To do. Since the lighting circuit 20 is off at the time point t0, an LED voltage (circuit voltage) is generated between the lighting circuit 20 and the LED lamp body 21.

  If this circuit voltage is left as it is, the overvoltage protection function works and the voltage rises to the overvoltage limit voltage Vu. Therefore, in the embodiment of the present invention, the control circuit 17 starts voltage control at a voltage value (Vu / 2) that is ½ of the overvoltage limit value Vu of the LED 22 when the AC constant current power supply 11 rises. The load adjustment circuit 18 forms a bypass circuit that bypasses the input current, adjusts the current flowing through the bypass circuit, and adjusts the voltage applied to the LED 22 to a voltage value (Vu / 2). . Therefore, when the AC constant current power supply 11 starts up at time t0, the circuit voltage (LED voltage) between the lighting circuit 20 and the LED lamp body 21 is ½ of the overvoltage limit value Vu of the LED 22 by the control circuit 17. It is held at the voltage value (Vu / 2).

  When lighting control is started at time t1, the lighting circuit 20 is turned on by the control circuit 17, current is supplied via the rectifier circuit 14, the load adjustment circuit 18, and the smoothing circuit 19, and the LED lamp 21 The LED 22 is controlled to be turned on. In this case, the lighting circuit 20 performs PWM so that the brightness of the LED 22 becomes a predetermined brightness corresponding to a predetermined current (luminosity ratio) supplied from the AC constant current power supply 11 according to a command from the control circuit 17. The LED current is controlled by the control.

  The circuit voltage value at the time of lighting of the LED 22 at this time t1 is stored in a temporary storage device (not shown) of the control circuit 17 as a circuit voltage value V11 at the start of lighting control after the AC constant current power supply 11 is started up. When the LED 22 is controlled to be turned off at time t2, the control circuit 17 starts lighting control in which the secondary side circuit voltage of the LED lighting device 13 is stored in the temporary storage device from the time of turning off (time t2). The load adjustment circuit 18 performs control so that the circuit voltage value V11 at that time is obtained. Therefore, when the LED 22 is in the off state (time t2 to time t3), the circuit voltage on the secondary side of the LED lighting device 13 is maintained at the circuit voltage value V11 at the start of lighting control.

  Next, when lighting control is started at time t3, the circuit voltage on the secondary side of the LED lighting device 13 is held at the circuit voltage value V11 at the time of starting lighting control stored in the temporary storage device. It is possible to prevent an overcurrent from flowing through the LED 22 during the lighting control at the time point t3. Similarly, when the LED 22 is off (time t4 to time t5, time t6 to time t7...), The secondary side circuit voltage of the LED lighting device 13 is maintained at the circuit voltage value V11 at the start of lighting control. Therefore, it is possible to prevent an overcurrent from flowing through the LED 22 during the lighting control at the time points t5 and t7.

  FIG. 3 is an operation waveform diagram showing another example of the operation of the LED lighting device according to the embodiment of the present invention. This example is different from the example shown in FIG. 2 in the state in which the AC constant current power supply 11 is supplied instead of the circuit voltage value at the start of the lighting control after the AC constant current power supply 11 is started up. The circuit voltage value at the start of lighting is stored in the temporary storage device of the control circuit 17.

  As in the case of FIG. 2, assuming that the AC constant current power supply 11 starts up at time t0 and current is input from the AC constant current power supply 11 to the LED lighting device 13, the LED is connected between the lighting circuit 20 and the LED lamp body 21. A voltage (circuit voltage) is generated, but the circuit voltage is held by the control circuit 17 at a voltage value (Vu / 2) that is ½ of the overvoltage limit value Vu of the LED 22.

  When the lighting control is started at time t1, the lighting circuit 20 is turned on by the control circuit 17, and the circuit voltage value V11 when the LED 22 is lit at the time t1 is set as the circuit voltage value V11. Store in the storage device.

  When the LED 22 is controlled to be turned off at time t2, the control circuit 17 starts the lighting control in which the secondary circuit voltage of the LED lighting device 13 is stored in the temporary storage device from the time of turning off (time t2). The load adjustment circuit 18 controls the voltage value V11. Therefore, when the LED 22 is in the off state (time t2 to time t3), the circuit voltage on the secondary side of the LED lighting device 13 is maintained at the circuit voltage value V11 at the start of lighting control. The process up to this point is the same as in the case of FIG.

  Next, when lighting control is started at time t3, the circuit voltage value at the start of lighting of the LED 22 at time t3 is updated and stored in the temporary storage device of the control circuit 17 as the circuit voltage value V31. When the LED 22 is controlled to be turned off at time t4, the circuit at the time of lighting control at time t3 when the circuit voltage on the secondary side of the LED lighting device 13 is stored in the temporary storage device from when the LED 22 is turned off (time t4). The load adjustment circuit 18 controls the voltage value V31. Therefore, when the LED 22 is off (time t4 to time t5), the circuit voltage on the secondary side of the LED lighting device 13 is maintained at the circuit voltage value V31 during lighting control at time t3.

  Similarly, whenever the LED 22 is controlled to be turned on, the circuit voltages V51 and V71 at the times t5 and t7 are updated and stored in the temporary storage device, and the LED 22 is turned off (time t6 to time t7...). The circuit voltage on the secondary side of the LED lighting device 13 is maintained at V51, V71,. As a result, when the LED 22 is in the extinguished state, the circuit voltage values V11, V31, V51,... At the previous lighting control are maintained, so that an overcurrent is generated in the LED 22 during the lighting control at the time points t3, t5, t7. It can be prevented from flowing.

  FIG. 4 is an operation waveform diagram showing another example of the operation of the LED lighting device according to the embodiment of the present invention. This example is updated with respect to the example shown in FIG. 3 every predetermined time during lighting control instead of the circuit voltage value at the start of lighting for each lighting control in a state where the AC constant current power supply 11 is supplied. The circuit voltage value is stored in the temporary storage device of the control circuit 17.

  As in the case of FIG. 3, assuming that the AC constant current power supply 11 starts up at time t0 and current is input to the LED lighting device 13 from the AC constant current power supply 11, the LED is connected between the lighting circuit 20 and the LED lamp body 21. A voltage (circuit voltage) is generated, but the circuit voltage is held by the control circuit 17 at a voltage value (Vu / 2) that is ½ of the overvoltage limit value Vu of the LED 22.

  When lighting control is started at time t1, the lighting circuit 20 is PWM-controlled by the control circuit 17, and the circuit voltage value V11 when the LED 22 is lit at this time t1 is set as the circuit voltage value V11. Store in the storage device. Up to this point, the process is the same as in FIG.

  Next, the circuit voltage values V12 to V1n are acquired every predetermined time during lighting control, and updated and stored in the temporary storage device of the control circuit 17 each time the circuit voltage values V12 to V1n are acquired. When the LED 22 is controlled to be extinguished at the time point t2, the control circuit 17 controls the secondary side circuit voltage of the LED lighting device 13 from the time when the LED 22 is extinguished (time point t1 to time point t2). The load adjustment circuit 18 controls the circuit voltage value V1n last updated and stored in the temporary storage device. Therefore, when the LED 22 is off (time t2 to time t3), the circuit voltage on the secondary side of the LED lighting device 13 is maintained at the circuit voltage value V1n last updated and stored in the temporary storage device.

  Similarly, when lighting control is started at time points t3, t5, t7,..., Circuit voltage values V31 to V3n, V51 to V5n at predetermined times during the lighting control of the LEDs 22 at time points t3, t5, t7. , V71 to V7n... Are obtained and updated and stored in the temporary storage device of the control circuit 17 each time the circuit voltage values V31 to V3n, V51 to V5n, V71 to V7n. When the LED 22 is controlled to be turned off at the time points t4, t6,..., The circuit voltage on the secondary side of the LED lighting device 13 is under lighting control from the time of turning off (time points t4, t6...). The load adjustment circuit 18 performs control so that the circuit voltage values V3n, V5n,... Last updated and stored in the temporary storage device at (time t3, time t4, time t5, time t6,...). Therefore, when the LED 22 is off (time t4 to time t5, time t6 to time t7...), The circuit voltage on the secondary side of the LED lighting device 13 is the circuit voltage value last updated and stored in the temporary storage device. V3n, V5n, etc. are maintained. As a result, when the LED 22 is in the extinguished state, the circuit voltage values V1n, V3n, V5n,... At the previous lighting control are maintained. It can be prevented from flowing.

  In the above description, the circuit voltage values V1n, V3n, V5n, etc. that were last updated and stored in the temporary storage device are stored, but the average value of the circuit voltage values that are updated every predetermined time during the lighting control, that is, The average value of V11 to V1n acquired at time t1 to t2 during lighting control, the average value of V31 to V3n acquired at time t3 to time t4, the average value of V51 to V5n acquired at time t5 to time t6, and so on. You may make it memorize | store in a temporary memory and use the average value of the circuit voltage value.

  Moreover, although the circuit voltage value of the lighting state of the LED 22 described above is stored in the temporary storage device of the control circuit 17, it may be stored in an external self-holding storage device. In this case, even when the control power supply of the control circuit 17 is turned off, the circuit voltage value of the lighting state of the LED 22 is held in the external self-holding storage device.

  According to the embodiment of the present invention, the circuit voltage at the time of lighting is stored, and when the LED 22 of the LED lamp device 21 is controlled to be turned off, the circuit output voltage at the time of lighting is controlled. Even so, the overcurrent does not flow to the LED 22, which leads to an improvement in the quality of the LED lighting device 13.

DESCRIPTION OF SYMBOLS 11 ... AC constant current power supply, 12 ... Rubber covering insulation transformer, 13 ... LED lighting device, 14 ... Rectification circuit, 15 ... Insulation current transformer, 16 ... Input current detection circuit, 17 ... Control circuit, 18 ... Load adjustment circuit, DESCRIPTION OF SYMBOLS 19 ... Smoothing circuit, 20 ... Lighting circuit, 21 ... LED lamp, 22 ... LED, 23 ... Current detection part, 24 ... Voltage detection part, 25 ... DC-DC converter

Claims (5)

A rectifier circuit for rectifying the AC power supply voltage;
A DC / DC converter for changing the output voltage supplied to the LED by inputting the output voltage of the rectifier circuit;
A lighting circuit for controlling the current supplied from the DC / DC converter to the LED according to the lighting control and extinguishing control of the LED;
A current detector for detecting the current of the LED;
A voltage detector for detecting an applied voltage to the LED or an output voltage of the DC / DC converter;
During the lighting control of the LED, the lighting circuit is controlled according to the detection signal of the current detection unit so that the brightness of the LED becomes a predetermined brightness, the LED current is controlled, and the detection signal of the voltage detection unit The output voltage of the DC / DC converter is controlled accordingly, and the DC / DC converter is set so that the applied voltage to the LED or the output voltage of the DC / DC converter becomes the voltage during LED lighting control when the LED is turned off. A control circuit for controlling
The LED lighting device characterized by comprising. The DC / DC converter is
A smoothing circuit for smoothing the current rectified by the rectifier circuit;
During the lighting control of the LED, a power supply circuit that applies the current smoothed by the smoothing circuit to the LED is formed, and when the current or voltage applied to the LED exceeds a predetermined value, the input current to the power supply circuit A circuit that bypasses the LED, adjusts the current flowing through the bypass circuit so that the current or voltage applied to the LED is constant, and controls the power supply circuit during LED turn-off control. A load adjustment circuit for controlling the voltage to be a circuit voltage value when the LED is lit;
The LED lighting device according to claim 1, further comprising:   The circuit voltage value at the time of lighting of the LED is a circuit voltage value at the start of lighting control after the AC power supply is started up, a circuit voltage value at the start of lighting for each lighting control with the AC power supply being supplied, 3. The LED lighting device according to claim 1, wherein the LED lighting device is one of a circuit voltage value updated every predetermined time during control and an average value of circuit voltage values every predetermined time during lighting control.   4. The LED lighting device according to claim 1, wherein the circuit voltage value at the time of lighting of the LED is stored in a temporary storage device of the control circuit or an external self-holding storage device.   5. The control circuit according to claim 1, wherein the control circuit starts lighting control at a preset voltage value smaller than an overvoltage limit value of the LED when the AC constant current power supply is started. 6. LED lighting device.

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