Dummy load device

Abstract

To enable stable phase-controlled dimming of an LED lighting fixture in a lighting duct.SOLUTION: To provide a dummy load device that can be attached to a lighting duct and can apply a steady load.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a phase control dimmer that is connected to a lighting duct rail (hereinafter referred to as a lighting duct) to which AC power is supplied, and to an LED lighting fixture. [Background technology]

[0002] The lighting duct is a device that is powered by a connected power source over the entire rail section, and can be used to attach lighting fixtures such as spotlights at any position on the rail. Because of its convenience, which allows any number of lighting fixtures to be attached at any position, it is widely used in facilities such as ordinary homes, stores, and museums.

[0003] Lighting ducts are regulated by the Japanese Industrial Standards, and are generally connected to a commercial AC power source with a two-wire power supply. In addition, because incandescent lamp lighting fixtures have been the norm, phase dimming is often used when dimming lighting.

[0004] There is also a high demand for LED lighting fixtures that are compatible with lighting ducts, and many such products are on the market. However, phase control dimming is a dimming method for incandescent bulbs, and in order to use it with LED lighting fixtures, it is necessary to convert the phase control dimming to a suitable output. For this reason, many technologies have been developed on the LED lighting fixture side that support phase dimming methods, and it is common for the dimming driver built into the LED lighting fixture to read the state of the phase angle supplied and control the amount of current supplied to the LED light source.

[0005] In addition, dimmers are also designed based on the resistive load of incandescent light bulbs, and in order for LED lighting fixtures to be compatible, they often have to be equipped with some kind of resistive load element. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-200844 A Summary of the Invention [Problem to be solved by the invention]

[0007] Phase control dimming uses a triac or MOSFET to cut out a certain angle range of the AC waveform and control the amount of current supplied to change the brightness. Due to the characteristics of the internal circuitry of LED lighting fixtures, there are regions in the AC voltage fluctuation cycle where the load current drops or stops flowing, causing waveform disturbances and preventing proper dimming. As mentioned above, to solve this problem, LED lighting fixtures are sometimes designed to incorporate a resistive load circuit to operate the dimmer properly, but this increases the power consumption of the fixture, so they are often designed to turn off the load circuit at a specific voltage value, which naturally results in a problem of larger fixtures. [Means for solving the problem]

[0008] The most important feature of the present invention is that light is received along an optical path inclined with respect to the direction perpendicular to the document so that the scanning position of the document or the position immediately before (or after) it can always be viewed. Effect of the Invention

[0009] The pseudo-load circuit of the present invention, which is attached to a lighting duct and consists of a rectifier circuit configured with bridge diodes and a constant current circuit configured with MOSFETs, allows the current rectified by the rectifier circuit to flow through the constant current circuit, thereby applying a steady load over the entire phase angle range of the phase control dimming waveform, thereby enabling stable on / off operation of the triac of the phase control dimmer. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of the present invention in use (Examples 1 and 2). [Diagram 2]1 is a voltage waveform shown by a lighting duct when the present invention is not used (Example 1). [Diagram 3] FIG. 1 is a circuit diagram of the present invention when used in a reverse phase dimmer (Example 1). [Figure 4] 1 is a voltage waveform shown by a lighting duct when the present invention is used (Example 1). [Diagram 5] 13 is a voltage waveform shown by a lighting duct when the present invention is not used (Example 2). [Figure 6] FIG. 1 is a circuit diagram of the present invention when used in a positive phase dimmer (Example 2). [Figure 7] 13 is a voltage waveform shown by a lighting duct when the present invention is used (Example 2). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Phase control dimmers are devices that adjust the current value to the load by controlling the conduction angle for each cycle of AC current. There are two types: positive phase types, which cut off the rising edge of the waveform and change the on position, and mainly use a triac and an on-delay timer, and negative phase types, which cut off the falling edge of the waveform and change the off position, and mainly use a MOSFET or IGBT (insulated gate bipolar transistor) and an off-delay timer.

[0012] One embodiment of the present invention is connected to an anti-phase type phase control dimmer, and can perform stable dimming.

[0013] Another embodiment of the present invention is connected to a positive phase type phase control dimmer to provide stable dimming. EXAMPLES

[0014] In this embodiment, the case where the phase control dimmer is an inverse phase type phase control dimmer will be described. FIG. 1 is a schematic diagram of the present invention in use. A dummy load device 101 of the present invention and an arbitrary number of LED lighting fixtures 104 are attached to a lighting duct 103, and a commercial AC power source is connected via an inverse phase control dimmer 102. The LED lighting fixture 104 is an LED lighting fixture that supports inverse phase control dimming. The LED lighting fixture 104 in this embodiment does not have a load circuit for stabilizing the phase control waveform, but one that has a load circuit may be used. The inverse phase control dimmer 102 uses an IGBT and an off delay timer, but the behavior is almost the same in other methods, so details will be omitted. The LED lighting fixture 104 is a fixture equipped with a power supply circuit and supports phase control dimming, and reads the input phase angle, and the power supply circuit outputs an appropriate output for the LED, such as PWM, to light it up.

[0015] First, in order to explain the effect of the present invention, the behavior of the voltage flowing through the LED lighting device 104 and the lighting duct when the dummy load device 101 according to the present invention is not attached to the lighting duct will be explained. FIG. 2 shows a voltage waveform shown by the lighting duct when the present invention is not used and the brightness is set to 50% with the dimmer. Point 201 is the ignition angle at which the dimmer 102 is turned off. As shown in the figure, the voltage does not drop completely after the ignition angle, but drops gradually. This is because when the dimmer 102 is turned off, the load circuit of the LED lighting device 104 becomes floating and the charge remaining in the load circuit gradually releases. Due to this gradual voltage drop, the LED lighting device 104 cannot correctly recognize the ignition angle, and the LED lighting device 104 cannot correctly light up at the brightness set by the dimmer 102.

[0016] 3 is a schematic circuit diagram of the present invention corresponding to a phase control dimmer of the reverse phase type. 310 is a rectifier circuit. It rectifies the current input through the lighting duct 103 and converts it into DC. Since it is a known general rectifier circuit using a bridge diode, detailed behavior when a commercial power source is connected is omitted. 320 is a constant current circuit. It constitutes a constant current circuit in the DC circuit after rectification by the rectifier circuit 310.

[0017] The current input through the lighting duct 103 is rectified by the bridge diode of the rectifier circuit 310, and flows into the constant current circuit 320 including a MOSFET and a resistor. As a result, even when the phase control dimmer 102 is turned off, that is, when the firing angle is reached, the charge remaining in the load circuit flows in and is quickly discharged.

[0018] Fig. 4 shows the voltage waveform shown by lighting duct 103 when the present invention is used and 50% brightness is set by phase control dimmer 102. Point 401 is the ignition angle at which the dimmer turns off. As shown in the figure, the voltage drops more quickly after the ignition angle compared to when the present invention is not used. This allows LED lighting fixture 104 to correctly recognize the ignition angle and light up at the brightness set by phase control dimmer 102.

[0019] In this way, in a lighting duct connected to the dummy load device of the present invention, the phase control waveform is correctly output only with the dimmer and the dummy load device, so there is no need to install a load circuit in the LED lighting fixture to stabilize the phase control waveform, which reduces the power consumption of the LED lighting fixture and also reduces the size by reducing the heat dissipation elements.Furthermore, by eliminating the fluctuation due to the load circuit, the impact of the number of LED lighting fixtures connected to the lighting duct can also be reduced. EXAMPLES

[0020] In this embodiment, the case where the phase control dimmer is a positive phase type phase control dimmer will be described. The usage state in this embodiment is also the same as that in the first embodiment except for the type of phase control dimmer, so it will also be described using FIG. 1. The dummy load device 101 of the present invention and an arbitrary number of LED lighting fixtures 104 are attached to a lighting duct 103, and a commercial AC power source is connected via a positive phase control dimmer 102. The LED lighting fixture 104 is an LED lighting fixture compatible with positive phase control dimming. The LED lighting fixture 104 in this embodiment does not have a load circuit for stabilizing the phase control waveform, but one having a load circuit may be used. The positive phase dimmer 102 uses a general triac.

[0021] Fig. 5 shows a voltage waveform shown by the lighting duct 103 when the present invention is not used and the brightness is set to 40% with the dimmer 102. Point 501 is the conduction angle at which the dimmer 102 is turned on. As shown in Fig. 5, a disturbed waveform occurs. This is because the load current drops or does not flow during the period when the dimmer 102 is off, and the holding current of the triac inside the dimmer can no longer be maintained, causing instability.

[0022] This phenomenon is caused by the characteristics of the internal circuit of the LED, and there is a region in the fluctuation cycle of the AC voltage where the load current drops or does not flow. To avoid this, as with the case of a reverse phase type phase control dimmer, LED lighting fixtures compatible with positive phase dimmers often have countermeasures such as a load circuit. The LED lighting fixture 104 is an LED lighting fixture compatible with phase control dimming. The LED lighting fixture 104 in this embodiment does not have a load circuit for stabilizing the phase control waveform, but one with a load circuit may be used.

[0023] FIG. 6 is a schematic circuit diagram of the present invention corresponding to a positive phase type phase control dimmer. 601 is a rectifier circuit. The current input through the lighting duct 103 is rectified and converted into direct current. Since it is a known general rectifier circuit using a bridge diode, detailed behavior when a commercial power source is connected is omitted. 602 is a constant current circuit. A constant current circuit is configured in the direct current circuit after rectification by the rectifier circuit 601. The current value of this constant current circuit 602 is designed to be a current value equal to or higher than the holding current value of the triac. The current input through the lighting duct 103 is rectified by the bridge diode of the rectifier circuit 601 and flows into the constant current circuit 602 including a MOSFET and a resistor. As a result, the holding current of the triac flows to the dimmer 102 except near the zero crossing where the operating voltage of the constant current circuit 602 is not satisfied, so that the internal circuit of the dimmer 102 can be operated stably.

[0024] Figure 7 shows the voltage waveform shown by the lighting duct when the present invention is used and the brightness is set to 40% with a positive phase type phase control dimmer. Point 701 is the conduction angle at which the dimmer turns on. As shown in the figure, there is no distortion in the waveform after the conduction angle compared to when the present invention is not used. This allows the LED lighting device 104 to correctly recognize the voltage shown by the dimmer 102 after the conduction angle, and to light up at the brightness set by the phase control dimmer 102.

[0025] In this way, in the lighting duct 103 connected to the dummy load device 101 of the present invention, the phase control waveform is correctly output only with the dimmer and the dummy load device, just like the reverse phase dimmer shown in the first embodiment, so there is no need to install a load circuit in the LED lighting fixture to stabilize the phase control waveform, which reduces the power consumption of the LED lighting fixture and further reduces the size by reducing the number of heat dissipation elements.Furthermore, by eliminating the fluctuation due to the load circuit, the effect of the number of LED lighting fixtures connected to the lighting duct can also be reduced.

[0026] The embodiments described in this specification are merely examples, and are not intended to limit the number or configuration of lighting fixtures. [Industrial Applicability]

[0027] In this way, a lighting duct connected to the dummy load device of the present invention can obtain a dramatic effect through stable dimming of LED lighting devices, and can promote energy conservation and miniaturization of LED lighting devices.

Claims

1. This pseudo-load device is a separate unit from the lighting fixture and can be attached to a lighting duct to which an LED dimming lighting fixture is attached and a phase-controlled dimming waveform is input. The pseudo-load device is characterized in that it comprises a rectifier circuit composed of bridge diodes and a constant current circuit composed of MOSFETs, and applies a steady load by passing the current rectified by the rectifier circuit through the constant current circuit.

2. 2. The dummy load device of claim 1, which is detachable from a lighting duct.

3. 3. The dummy load device of claim 1 or 2, wherein the phase control dimmer is an anti-phase phase dimmer.

4. 3. The pseudo load device of claim 1 or 2, wherein the phase control dimmer is a positive phase dimmer, and the current value of the constant current circuit is equal to or greater than a triac holding current built into the dimmer.

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