JP2013122879A - Lighting control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a lighting control device against damage from an overload such as a high wattage type low voltage halogen lamp while adapting the lighting control device to support a plurality of types of lamps such as an LED lamp and a low wattage type low voltage halogen lamp.SOLUTION: A lighting control device 10 includes: a rectification circuit 11 for full-wave-rectifying a commercial power supply 21; an inverter circuit 14 for converting a full-wave-rectified DC voltage to an AC voltage; a lighting circuit 15 for supplying the AC-converted voltage to light a lamp 22; a control power circuit 12 for supplying power to the inverter circuit 14; a current feedback circuit 13 for feeding back a current derived from the lighting circuit 15; a first protection circuit 16 for detecting a current flowing through the inverter circuit 14 which is greater than a first predetermined current to perform a protective action; and a second protection circuit 17 for detecting a current flowing through the inverter circuit 14 which is greater than a second predetermined current (less than the first predetermined current) to perform a protective action.

Description

  The present invention relates to a lighting control device.

  An electronic transformer is known as a lighting device for lighting a low-volt halogen lamp. An electronic transformer, for example, full-wave rectifies a voltage input from a commercial power supply using a rectifier circuit, converts the full-wave rectified DC voltage into a high-frequency AC voltage using a switching element such as a transistor, and up to approximately 12 volts using a step-down transformer. Step down and apply to halogen lamp.

  In recent years, LED lamps (hereinafter simply referred to as “LED lamps”) that incorporate a control device that turns on LEDs by converting the output of the electronic transformer into direct current have been put on the market. Since this LED lamp has the same base as the low volt halogen lamp, it can be mounted on an existing low volt halogen lamp fixture, and the power consumption is about 1/5 of that of the low volt halogen lamp. Can be suppressed.

  By dedicating the electronic transformer to a load equivalent to this LED lamp, it becomes possible to adopt low-rated parts, and therefore the electronic transformer can be manufactured at low cost. In addition, low-rated parts are small in size, and parts required to dissipate heat from the heat-generating parts can be reduced, so that the electronic transformer can be downsized.

  However, as described above, since the base of the low-voltage halogen lamp and the LED lamp is the same, it is possible to attach a high-watt type low-voltage halogen lamp to a low-watt dedicated electronic transformer. When a high wattage type halogen lamp is installed, an electronic transformer dedicated to low wattage will fail due to overload.

  Therefore, an overload protection circuit for detecting and protecting a high watt type low volt halogen lamp is required.

  Conventionally, as an overload protection circuit, there is a circuit that detects an overcurrent of an oscillation switching element and stops oscillation (see, for example, Patent Document 1).

JP 2000-286087 A

  In a low-volt halogen lamp, when the filament is in a cold state at the start, the filament resistance value is smaller than the normal resistance value, and the load current increases compared to when the lamp is lit. Especially in a high watt type low volt halogen lamp, the current at the start is very large.

  By setting the operation threshold of the conventional overload protection circuit to the current at the time of starting, it is possible to detect that a high watt type low volt halogen lamp is mounted. However, the low-volt halogen lamp has a characteristic that the filament warms up as it is repeatedly started and the resistance value is comparable to that during lighting. Therefore, if the threshold of the overload protection circuit is set to the current at start-up, the overload protection circuit will not operate even if a high wattage type low volt halogen lamp is installed, and the low volt halogen lamp May light up. In this case, as described above, the electronic transformer fails due to overload.

  An object of the present invention is to suppress lighting and prevent a failure of an electronic transformer from an overload when a high watt type low-volt halogen lamp is mounted.

  The present invention, for example, allows a plurality of types of lamps such as LED lamps and low wattage type low volt halogen lamps to be used in the lighting control device, while failure of the lighting control device due to overload such as a high watt type low volt halogen lamp. The purpose is to prevent.

A lighting control device according to one aspect of the present invention includes:
An inverter circuit that inputs a DC voltage, converts the input DC voltage into an AC voltage by oscillation, and outputs the AC voltage;
A lighting circuit that inputs the AC voltage output from the inverter circuit, outputs the input AC voltage, and lights an external lamp;
A first protection circuit that detects current flowing through the inverter circuit and suppresses oscillation of the inverter circuit when the detected current is greater than a predetermined first threshold;
The current flowing through the inverter circuit is detected after a lapse of a predetermined time from the start of lighting of the lamp by the lighting circuit, and the detected current is larger than a predetermined second threshold value smaller than the first threshold value. And a second protection circuit for suppressing oscillation of the inverter circuit.

  In one aspect of the present invention, the lighting control device includes a first protection circuit and a second protection circuit that detect a current flowing through the inverter circuit. The first protection circuit suppresses oscillation of the inverter circuit when the detected current is larger than a predetermined first threshold value. The second protection circuit suppresses oscillation of the inverter circuit when a current detected after a predetermined time has elapsed after the lamp starts lighting is larger than a predetermined second threshold value smaller than the first threshold value. Therefore, according to one aspect of the present invention, it is possible to use a plurality of types of lamps such as an LED lamp and a low wattage type low volt halogen lamp in the lighting control device, while the high watt type low volt halogen lamp and the like can be used. It becomes possible to prevent a failure of the lighting control device from the load.

FIG. 2 is a circuit diagram illustrating a configuration example of a lighting control device according to the first embodiment. The figure which shows the output current waveform after starting a low volt halogen lamp. The figure which shows the output current waveform when a lamp short-circuits. The figure which shows the output electric current waveform after starting the low volt halogen lamp in the state where the filament was warm. A table comparing the power consumption of low-voltage halogen lamps and LED lamps. The circuit diagram which shows the structural example of the LED lamp connected to the electronic transformer to which the lighting control apparatus which concerns on Embodiment 1 is applied. 6 is a graph showing a detected current and an operation start time of the protection circuit of the lighting control device according to the first embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of each embodiment, the directions such as “up”, “down”, “left”, “right”, “front”, “back”, “front”, “back” are However, it is not intended to limit the arrangement or orientation of devices, instruments, parts, or the like.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration example of a lighting control device 10 according to the present embodiment.

  In FIG. 1, the lighting control device 10 includes a rectifier circuit 11, a control power supply circuit 12, a current feedback circuit 13, an inverter circuit 14, a lighting circuit 15, a first protection circuit 16, and a second protection circuit 17.

  The rectifier circuit 11 performs full-wave rectification on the AC voltage applied from the commercial power supply 21 and outputs a DC voltage. In this example, the rectifier circuit 11 is configured as a diode bridge, but other configurations may be employed.

  The control power supply circuit 12 supplies power to the inverter circuit 14.

  The current feedback circuit 13 feeds back the current obtained from the lighting circuit 15.

  The inverter circuit 14 receives the DC voltage output from the rectifier circuit 11, converts the input DC voltage into an AC voltage by oscillation, and outputs the AC voltage. In this example, the inverter circuit 14 is composed of two switching elements 14a and 14b for oscillation, but other configurations may be adopted. In this example, transistors are used as the switching elements 14a and 14b, but other types of elements may be used. In this example, the inverter circuit 14 is mounted by a self-excited half bridge method driven by a current fed back from the current feedback circuit 13, but other methods may be adopted.

  The lighting circuit 15 receives the AC voltage output from the inverter circuit 14 and outputs the input AC voltage to light the external lamp 22 (light source).

  The first protection circuit 16 detects the current flowing through the inverter circuit 14, and suppresses oscillation of the inverter circuit 14 when the detected current is larger than a predetermined first threshold c1.

  In this example, the first protection circuit 16 includes a resistor 16a and a control unit 16b. The resistor 16 a is connected between the emitter terminal of the low-voltage side switching element 14 b of the inverter circuit 14 and the GND (ground) of the rectifier circuit 11. The control unit 16b is an IC, and stores the first threshold value c1 in advance in a built-in storage unit (not shown). The control unit 16b is connected to a connection point between the resistor 16a and the low-voltage side switching element 14b of the inverter circuit 14, and detects a current flowing through the inverter circuit 14 with the resistor 16a. The control unit 16b is also connected to the control power circuit 12, and compares the current detected by the resistor 16a with the first threshold value c1 stored in the storage unit, and if the detected current is larger than the first threshold value c1. Then, the power supply from the control power circuit 12 to the inverter circuit 14 is stopped. That is, when a current larger than the first threshold value c1 flows through the inverter circuit 14, the control unit 16b detects the current with the resistor 16a and stops the oscillation of the inverter circuit 14.

  The second protection circuit 17 detects a current flowing through the inverter circuit 14 after a lapse of a predetermined time t1 after the lamp 22 starts lighting by the lighting circuit 15, and the detected current is determined in advance to be smaller than the first threshold c1. If it is larger than the second threshold value c2, the oscillation of the inverter circuit 14 is suppressed.

  In this example, the second protection circuit 17 includes resistors 17a and 17b and a control unit 17c. The resistors 17 a and 17 b are connected to the base terminal of the low voltage side switching element 14 b of the inverter circuit 14 and the current feedback circuit 13. The resistors 17a and 17b are connected in series. The control unit 17c is an IC, and stores the second threshold value c2 in advance in a built-in storage unit (not shown). The control unit 17c is connected to a connection point between the resistors 17a and 17b, and detects the current flowing through the inverter circuit 14 with the resistors 17a and 17b. The control unit 17c is connected to the control power supply circuit 12 in the same manner as the control unit 16b of the first protection circuit 16, and the current detected by the resistors 17a and 17b and the second threshold value c2 stored in the storage unit. In comparison, if the detected current is larger than the second threshold c2, the power supply from the control power supply circuit 12 to the inverter circuit 14 is stopped. However, the control unit 17c stands by until a predetermined time t1 elapses after the lamp 22 starts lighting. That is, when a current larger than the second threshold c2 flows to the inverter circuit 14 after a predetermined time t1 has elapsed since the start of the lamp 22, the control unit 17c detects the current with the resistors 17a and 17b and oscillates the inverter circuit 14. Stop.

  FIG. 2 is a diagram showing an output current waveform after starting the low-volt halogen lamp.

  As shown in FIG. 2, when a low volt halogen lamp is connected as the lamp 22 to the lighting control device 10, the output current becomes excessive when starting, and when the filament warms up after a predetermined time t1, Transition to current.

  In the first protection circuit 16, the first threshold value c1 is determined in accordance with the output current at the start of the low volt halogen lamp having a predetermined watt w1 (predetermined wattage). Therefore, when a low volt halogen lamp having a watt higher than the predetermined watt w1 is connected to the lighting control device 10, the first protection circuit 16 detects an overcurrent at the time of starting and suppresses oscillation of the inverter circuit 14.

  FIG. 3 is a diagram showing an output current waveform when the lamp 22 is short-circuited.

  As shown in FIG. 3, even when the lamp 22 is short-circuited, the output current is excessive.

  As described above, in the first protection circuit 16, the first threshold value c1 is determined in accordance with the output current at the start of the low volt halogen lamp having the predetermined watt w1, and the lamp 22 is short-circuited. If the output current is smaller than. Therefore, when the lamp 22 connected to the lighting control device 10 is short-circuited, the first protection circuit 16 detects an overcurrent and suppresses oscillation of the inverter circuit 14.

  FIG. 4 is a diagram showing an output current waveform after starting the low volt halogen lamp with the filament warmed.

  As shown in FIG. 4, when a low volt halogen lamp is connected to the lighting control device 10 as the lamp 22, when the low volt halogen lamp is started with the filament warmed, its output current is The current is about the same.

  In the second protection circuit 17, the second threshold value c2 is determined in accordance with the output current when the low volt halogen lamp of the predetermined watt w1 is lit. Therefore, when the low volt halogen lamp having a watt higher than the predetermined watt w1 is connected to the lighting control device 10, the second protection circuit 17 is lit even if the low volt halogen lamp is started with the filament warmed up. The current of the hour is detected and oscillation of the inverter circuit 14 is suppressed.

  Here, the current detected by the first protection circuit 16 is larger than that of the second protection circuit 17, and it is necessary to instantaneously suppress the oscillation of the inverter circuit 14 in order to prevent the lighting control device 10 from being damaged due to an overcurrent. Therefore, the detection (response) speed is mounted so that the first protection circuit 16 is faster than the second protection circuit 17. For example, as will be described later, it is desirable that the second protection circuit 17 starts the operation after a time longer than the time required to start the low-volt halogen lamp having the predetermined watt w1 has elapsed as the predetermined time t1. .

  FIG. 5 is a table comparing the power consumption of the low-volt halogen lamp and the LED lamp.

  FIG. 5 compares the lamp power consumed when the same low brightness is obtained with a general low-volt halogen lamp and an LED lamp. For example, to obtain a brightness equivalent to a 10 watt LED lamp using a low volt halogen lamp, a 50 watt high watt type low volt halogen lamp is required. Similarly, to obtain the same brightness as a 7 watt or 4 watt LED lamp, high wattage type low volt halogen lamps of 35 watt and 20 watt are required.

  For example, in an electronic transformer dedicated to LED lamps of 10 watts or less and capable of operating a low volt halogen lamp with the same output, the current at the start of a 10 watt low volt halogen lamp is a high watt type low volt halogen lamp. It becomes larger than the current when the lamp is turned on. Therefore, the first protection circuit 16 determines the first threshold value c1 in accordance with the output current at the start of the 10 watt low volt halogen lamp, and the second protection circuit 17 sets the 10 watt low volt halogen lamp. If the second threshold value c2 is determined according to the output current during lighting, the lighting control device 10 according to the present embodiment can be applied to the electronic transformer as described above.

  FIG. 6 is a circuit diagram illustrating a configuration example of the LED lamp 31 connected to the electronic transformer 30 to which the lighting control device 10 is applied.

  In FIG. 6, an LED lamp 31 turns on the rectifier circuit 32 that rectifies the high-frequency AC voltage of the electronic transformer 30, the smoothing circuit 33 that smoothes the full-wave rectified DC voltage, and the LED 35, and the current flowing through the LED 35 And a lighting circuit 34 that is controlled to be constant.

  Since the smoothing circuit 33 is charged when the LED lamp 31 is started, an overcurrent flows. This overcurrent is greater than the current when the high watt type low volt halogen lamp is lit. Further, as described above, the current at the time of starting the low watt type low volt halogen lamp is also larger than the current at the time of lighting of the high watt type low volt halogen lamp. Therefore, in the electronic transformer 30, the first threshold value c1 of the first protection circuit 16 is larger than the current at the start of the LED lamp 31 or the low watt type low volt halogen lamp (that is, the high watt type low volt). If the current value is not set to a value larger than the current when the halogen lamp is lit, the first protection circuit 16 will operate when the LED lamp 31 or the low wattage type low volt halogen lamp is started.

  FIG. 7 is a graph showing detected currents and operation start times of the first protection circuit 16 and the second protection circuit 17 of the lighting control device 10.

  As shown in FIG. 7, for example, since the output current at the start of a 10-watt low-volt halogen lamp is about 7 A or less, the first threshold c1 of the first protection circuit 16 is set to about 7 A. That is, the first protection circuit 16 instantaneously detects the current that flows when the lamp 22 starts, and suppresses oscillation of the inverter circuit 14 if the detected value exceeds about 7A.

  Further, for example, since the output current when the 10-watt low-volt halogen lamp is turned on is about 1 A or less, the second threshold c2 of the second protection circuit 17 is set to about 1 A. That is, the second protection circuit 17 becomes operable about 100 ms after the current at the time of starting the low-volt halogen lamp becomes the current at the time of lighting, detects the current flowing when the lamp 22 is lit, and the detected value becomes about 1A. If it exceeds, the oscillation of the inverter circuit 14 is suppressed.

  By doing so, the electronic transformer 30 (lights up) due to overload at the time of start-up and lighting of the high watt type low volt halogen lamp, and when the lamp 22 including the low watt type low volt halogen lamp and the LED lamp 31 is short-circuited. It is possible to prevent a failure of the control device 10).

  As described above, the lighting control device 10 according to the present embodiment includes the rectifier circuit 11 that performs full-wave rectification of the commercial power supply 21, the inverter circuit 14 that converts full-wave rectified DC voltage into AC voltage, and AC. A lighting circuit 15 that supplies the voltage converted into the voltage to light the lamp 22, a control power circuit 12 that supplies power to the inverter circuit 14, and a current feedback circuit 13 that feeds back the current obtained from the lighting circuit 15. Prepare. The inverter circuit 14 is a self-excited half-bridge type that inputs a drive current from the current feedback circuit 13. The lighting control device 10 further detects a current larger than a predetermined first current flowing through the inverter circuit 14 and performs a protection operation, and a predetermined second current (predetermined predetermined) flowing through the inverter circuit 14. A second protection circuit 17 that performs a protection operation by detecting a current larger than (less than the first current) by a voltage generated at a location where the low voltage side switching element 14b of the inverter circuit 14 and the current feedback circuit 13 are connected. Prepare. At this time, the first protection circuit 16 and the second protection circuit 17 limit the current of the control power supply circuit 12 and suppress the oscillation of the inverter circuit 14 as a protection operation. The response speed of the first protection circuit 16 is faster than the response speed of the second protection circuit 17.

  According to the present embodiment, the first protection circuit 16 detects a current larger than that during lighting, such as an overcurrent at the start of a high watt type low-volt halogen lamp or a short-circuit current at the time of short-circuiting the lamp 22. Thus, the second protection circuit 17 can detect the current when the high watt type low volt halogen lamp is lit to suppress the oscillation and prevent the lighting control apparatus 10 from being overloaded. .

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  In the present embodiment, the first protection circuit 16 and the second protection circuit 17 (or at least one of them) alternately repeat the stop and start of oscillation of the inverter circuit 14 so that the inverter circuit 14 oscillations are suppressed.

  About the structure of the lighting control apparatus 10 which concerns on this Embodiment, it is the same as that of Embodiment 1, For example, what was shown in FIG. 1 can be used.

  In FIG. 1, the control power supply circuit 12 also serves as a starting power supply for the inverter circuit 14. The first protection circuit 16 and the second protection circuit 17 short-circuit between the control power supply circuit 12 and the GND of the rectifier circuit 11 as a protection operation. As a result, the inverter circuit 14 stops and the current does not flow. Thereafter, the first protection circuit 16 and the second protection circuit 17 cancel the short circuit between the control power supply circuit 12 and the GND of the rectifier circuit 11. Then, the inverter circuit 14 is started again. The first protection circuit 16 and the second protection circuit 17 suppress oscillation by alternately repeating such stop and start of the inverter circuit 14.

  By suppressing this oscillation, the lamp 22 such as a high watt type low volt halogen lamp repeatedly blinks, and it becomes possible to announce to the end user that a different kind of lamp or a malfunctioning lamp is mounted.

  As mentioned above, although embodiment of this invention was described, you may implement in combination of 2 or more among these embodiment. Alternatively, one of these embodiments may be partially implemented. Alternatively, two or more of these embodiments may be partially combined. In addition, this invention is not limited to these embodiment, A various change is possible as needed.

  DESCRIPTION OF SYMBOLS 10 Lighting control apparatus, 11 Rectifier circuit, 12 Control power supply circuit, 13 Current feedback circuit, 14 Inverter circuit, 14a, 14b Switching element, 15 Lighting circuit, 16 1st protection circuit, 16a Resistance, 16b Control part, 17 2nd protection Circuit, 17a, 17b Resistance, 17c Control unit, 21 Commercial power supply, 22 lamp, 30 Electronic transformer, 31 LED lamp, 32 Rectifier circuit, 33 Smoothing circuit, 34 Lighting circuit, 35 LED

Claims (4)

An inverter circuit that inputs a DC voltage, converts the input DC voltage into an AC voltage by oscillation, and outputs the AC voltage;
A lighting circuit that inputs the AC voltage output from the inverter circuit, outputs the input AC voltage, and lights an external lamp;
A first protection circuit that detects current flowing through the inverter circuit and suppresses oscillation of the inverter circuit when the detected current is greater than a predetermined first threshold;
The current flowing through the inverter circuit is detected after a lapse of a predetermined time from the start of lighting of the lamp by the lighting circuit, and the detected current is larger than a predetermined second threshold value smaller than the first threshold value. And a second protection circuit for suppressing oscillation of the inverter circuit.   The at least one of the first protection circuit and the second protection circuit suppresses oscillation of the inverter circuit by alternately repeating stop and start of oscillation of the inverter circuit. 1 lighting control device. The first threshold value is larger than the output current at the start of the lamp having a predetermined wattage,
The lighting control device according to claim 1, wherein the second threshold value is larger than an output current when the lamp having the predetermined wattage is turned on.   4. The lighting control device according to claim 3, wherein the predetermined time is longer than a time taken to start the lamp having the predetermined wattage.

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