JP6970941B2 - Power supply for lighting - Google Patents

Description

The present invention relates to a power supply device for lighting using an LED (Light Emitting Device) as a light source.

Patent Document 1 discloses a power supply device for lighting corresponding to a phase control method. This power supply device includes a control unit and a power conversion unit. The control unit determines the dimming rate according to the change in the conduction angle of the supplied AC voltage, and outputs a control signal according to the determined dimming rate. The power conversion unit converts the AC voltage according to the control signal and supplies it to the lighting load.

Japanese Unexamined Patent Publication No. 2016-666488

An object of the present invention is to make it possible to suppress the occurrence of light skipping in a power supply device for lighting at the time of fade-out in which the amount of light of a light source is gradually reduced.

In order to solve the above problems, the lighting power supply device corresponding to the phase control method for lighting using an LED as a light source according to an embodiment of the present invention detects the phase of the phase-controlled AC power. A control circuit that generates a dimming signal that indicates the dimming level of the light source according to the detected phase, and the AC power is converted into DC power corresponding to the dimming level indicated by the dimming signal. The control circuit has a predetermined delay time in the generation of the dimming signal, and the control circuit has a fade-out control for gradually lowering the dimming level. The dimming signal is adjusted so that the dimming level indicated by the dimming signal reaches the dimming lower limit value before the light source is turned off due to the decrease in the AC power.

According to the present invention, it is possible to suppress the occurrence of light skipping at the time of fading out.

Schematic configuration of the lighting power supply according to the embodiment Example of phase-controlled AC power waveform A flowchart showing an operation example of the adjustment circuit in the embodiment. The figure which conceptually shows the adjustment example of the dimming instruction value A flowchart showing an example of the adjustment value determination process. Diagram for explaining an example of fading time calculation

Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. The following description of each embodiment is merely exemplary and is not intended to limit the invention, its applications or its uses.

FIG. 1 shows a schematic configuration of a power supply device for lighting according to an embodiment. As shown in FIG. 1, the lighting power supply device according to the embodiment is a lighting power supply device using an LED as a light source 10. The lighting power supply device includes a power conversion circuit 20 and a control circuit 50. The power conversion circuit 20 receives AC power from the AC power supply 1, converts the received AC power into DC power, and supplies the received AC power to the light source 10. Here, the lighting power supply device is a power supply device corresponding to the phase control method, and the supplied AC power is phase-controlled according to, for example, a user operation.

The control circuit 50 includes a phase detection circuit 30 and a dimming circuit 40. The phase detection circuit 30 is a circuit that detects the phase of the AC power supplied to the power conversion circuit 20, and outputs a phase detection signal indicating the detected phase value. The dimming circuit 40 is configured by, for example, a microcomputer, receives a phase detection signal output from the phase detection circuit 30, and indicates a dimming level of the light source 10 according to the phase value indicated by the phase detection signal. Generates and outputs an optical signal. Here, it is assumed that the dimming signal is a PWM signal indicating the dimming level by the pulse width. The dimming signal, which is a PWM signal, is given to the gate of the switching elements 21 and 22 included in the power conversion circuit 20. That is, the control circuit 50 detects the phase of the AC power under phase control, and generates a dimming signal indicating the dimming level of the light source 10 according to the detected phase.

FIG. 2 is an example of a waveform of AC power subjected to phase control. In the phase control of FIG. 2, in the half cycle of the AC power V1, the time VT1 at which the AC power is actually output is changed according to the dimming level. The phase detection circuit 30 detects the voltage effective value of the supplied AC power and outputs this as a phase detection signal. The dimming circuit 40 obtains a dimming instruction value from the phase detection signal and outputs a dimming signal indicating the dimming instruction value.

Here, the phase control type lighting power supply device has a problem that the dimming level fluctuates due to noise and fluctuation of the input voltage. Therefore, in order to have resistance to noise and fluctuation of the input voltage, a control is used in which the dimming level is changed with a constant time constant with respect to the change of the input voltage.

However, when a control having such a time constant is used, there arises a problem that light skipping occurs at the time of fading out. That is, at the time of fading out, the dimming signal changes with a time constant delay from the phase detection signal, so that the phase detection signal becomes zero while the dimming signal still shows a high dimming level. In other words, while the dimming signal still shows a high dimming level, the supply of AC power to the power conversion circuit 20 is cut off, and the light source 10 is forcibly turned off. This is the occurrence of so-called light skipping.

Therefore, in the present embodiment, at the time of fade-out, the light source 10 is not turned off due to a decrease in the power supply to the power conversion circuit 20 while the dimming signal still shows a high dimming level. That is, the occurrence of light skipping is suppressed. Therefore, in the fade-out control for gradually lowering the dimming level, the control circuit 50 makes the dimming level indicated by the dimming signal reach zero before the light source 10 is turned off due to the decrease in the AC power. In addition, adjust the dimming signal.

FIG. 3 is a flowchart showing an operation example of the adjustment circuit 40 in the present embodiment. The adjustment circuit 40 converts the phase detection value D indicated by the phase detection signal received from the phase detection circuit 30 into the dimming instruction value d1 (S11). Here, it is assumed that the phase detection value D in a predetermined period is averaged and the phase detection value D after averaging is converted into the dimming instruction value d1. The averaging period corresponds to the time constant described above. The conversion from the phase detection value D to the dimming instruction value d1 may be performed, for example, according to a conversion table or conversion formula previously possessed by the adjustment circuit 40. Then, the adjustment circuit 40 outputs a dimming signal indicating the obtained dimming instruction value d1 to the power conversion circuit 20 (S12).

Then, the adjustment circuit 40 checks whether or not the phase detection value D has decreased for a predetermined time (S13). When the phase detection value D is decreasing for a predetermined time (Yes in S13), the process proceeds to step S20. If not (No in S13), the operation from step S11 is repeated. If the phase detection value D is decreasing for a predetermined time, it is highly possible that the fade-out operation is being performed. Therefore, the process shifts to the fade-out control from step S20, in which the dimming level is gradually lowered.

In step S20, the adjustment value K used for adjusting the dimming instruction value d1 is determined. The details of step S20 will be described later. After that, the adjustment circuit 40 averages the phase detection value D indicated by the phase detection signal received from the phase detection circuit 30 and converts it into the dimming instruction value d1 (S14). Further, the dimming instruction value d1 is adjusted to the dimming instruction value d2 based on the adjustment value K determined in step S20 (S15). By this adjustment, so-called light skipping does not occur. Then, the adjustment circuit 40 outputs a dimming signal indicating the adjusted dimming instruction value d2 to the power conversion circuit 20 (S16).

FIG. 4 is a diagram conceptually showing an example of adjusting the dimming instruction value. Now, it is assumed that the fade-out operation is performed when the dimming instruction value is the value d1. In this case, since there is a time difference τ (time constant) between the phase detection value and the dimming instruction value, the dimming instruction value starts to decrease after a delay of time τ from the start of decrease of the phase detection value. Therefore, when the light source 10 is turned off and the fade time T required until the fade-out is completed has elapsed, the dimming instruction value is not yet zero and has a value d0. That is, the light source 10 that emits the amount of light corresponding to the dimming instruction value d0 suddenly goes out, so-called light skipping occurs.

On the other hand, in the present embodiment, the dimming instruction value d1 is adjusted to the value d2 so that the dimming instruction value becomes zero when the fade time T elapses. This makes it possible to suppress the occurrence of light skipping.

Returning to the flow of FIG. 3, the adjustment circuit 40 checks whether or not the adjusted dimming instruction value d2 is lower than the dimming instruction value corresponding to the current phase detection value D (S17). If the dimming instruction value d2 is lower than the dimming instruction value corresponding to the current phase detection value D, it is highly possible that the fade-out operation has not been performed. Therefore, when the value is lower (Yes in S17), the process deviates from the fade-out control and returns to step S11. On the other hand, if this is not the case, the process returns to step S14 and the dimming instruction value d1 is adjusted.

FIG. 5 is a flowchart showing an example of the process of step S20, that is, the determination of the adjustment value K. Here, in order to make the explanation easy to understand, it is assumed that the phase detection value D and the dimming instruction value d are in a proportional relationship (d = D × β: β is a coefficient).

First, the time change α is obtained for the phase detection value D (S21). Then, the fade time T is obtained by using the obtained time change α (S22).

FIG. 6 is a diagram for explaining an example of calculating the fade time T. As shown in FIG. 6, when the phase detection value gradually decreases from the value D1, the amount of change Dn at time tun is obtained, and the time change α is obtained by the following equation.

α = Dn / tun
Then, the fade time T is calculated by the following equation.

T = D1 / α
Then, the amount of light skipping d0 when the light is turned off is obtained (S23), and the adjustment value K is determined (S24). The amount of light skipping d0 is calculated by the following equation.

d0 = d1-α × β × T
Then, the adjustment value K is obtained by the following equation.

K = -d0 / T
In this case, the adjustment in step S15 of FIG. 3 is performed according to the following equation.

d2 = d1 + K
As described above, according to the present embodiment, the lighting power supply device detects the phase of the AC power under phase control, and generates a dimming signal indicating the dimming level of the light source 10 according to the detected phase. A control circuit 50 is provided, and a power conversion circuit 20 that converts AC power into DC power corresponding to a dimming level indicated by a dimming signal and supplies the AC power to the light source 10. The control circuit 50 has a predetermined time constant (delay time) in the generation of the dimming signal, and in the fade-out control that gradually lowers the dimming level, the dimming occurs when the fade time T elapses. Adjust the dimming indicated value so that the indicated value becomes zero. As a result, it is possible to suppress the occurrence of so-called light skipping, in which the light source 10 is turned off while the dimming instruction value is high.

(Other operation examples)
The operation of the lighting power supply device according to the present embodiment is not limited to the above-mentioned example. Hereinafter, other operation examples will be described.

-Operation example 1
In the above-described embodiment, the dimming instruction value d1 is adjusted to the value d2 so that the dimming instruction value becomes zero when the fade time T elapses. However, it is not always necessary to set the dimming instruction value to zero when the fade time T has elapsed. That is, when the fade time T elapses, the dimming instruction value may be adjusted so as to be a dimming level at which the light source 10 does not emit light, that is, a dimming lower limit value.

-Operation example 2
Further, the dimming instruction value may be adjusted to zero or the dimming lower limit value before the fade time T elapses. Even in this case, it is possible to suppress the occurrence of so-called light skipping, in which the light source 10 is turned off while the dimming instruction value is high.

-Operation example 3
In the above-described embodiment, in the fade-out control, the adjustment is performed by adding the adjustment value K to the dimming instruction value d1. However, the method for adjusting the dimming instruction value is not limited to the method shown here. For example, the adjustment may be performed by multiplying the dimming instruction value by the adjustment value or dividing by the adjustment value.

As described above, the power supply device corresponding to the phase control method for lighting using an LED as a light source according to the present embodiment detects the phase of the phase-controlled AC power, and according to the detected phase, A control circuit 50 that generates a dimming signal that indicates the dimming level of the light source 10, and a power conversion circuit that converts AC power into DC power corresponding to the dimming level indicated by the dimming signal and supplies it to the light source 10. 20 and. The control circuit 50 has a predetermined delay time in the generation of the dimming signal, and in the fade-out control for gradually lowering the dimming level, before the light source 10 is turned off due to the decrease in the AC power. , Adjust the dimming signal so that the dimming level indicated by the dimming signal reaches the dimming lower limit value.

As a result, at the time of fade-out, the dimming level indicated by the dimming signal generated by the control circuit 50 reaches the dimming lower limit value before the light source 10 is turned off due to the decrease in the AC power. Therefore, while the dimming signal still shows a high dimming level, it is possible to suppress the occurrence of so-called light skipping, in which the light source 10 is turned off due to a decrease in the power supply to the power conversion circuit 20. ..

Further, the control circuit 50 detects the phase of the AC power and generates a phase detection signal indicating the detected phase value, and the phase detection circuit 50 receives the phase detection signal and receives the phase detection signal according to the phase value indicated by the phase detection signal. It may be provided with a dimming circuit 40 for generating a dimming signal. As a result, in the fade-out control, the control circuit sets the dimming signal so that the dimming level indicated by the dimming signal reaches the dimming lower limit value before the light source 10 is turned off due to the decrease in the AC power. Can be adjusted.

Further, the dimming circuit 40 obtains the fade time required until the end of the fade-out from the time change of the phase value, so that the dimming level indicated by the dimming signal reaches the dimming lower limit value before the fade time elapses. In addition, the dimming signal may be adjusted. Thereby, at the time of fading out, it is possible to control the dimming level so as to surely reach the dimming lower limit value before the light source 10 is turned off due to the decrease of the AC power.

(Other embodiments)
As described above, embodiments have been described as an example of the techniques disclosed in this application. However, the technique in the present disclosure is not limited to this, and can be applied to embodiments in which changes, replacements, additions, omissions, etc. are made as appropriate. It is also possible to combine the components described in the above embodiment to form a new embodiment.

For example, in the above-described embodiment, when the phase detection value D is decreasing for a predetermined time, the process shifts to the fade-out control. However, the conditions or timing for shifting to fade-out control are not limited to this. For example, a signal indicating that the fade-out operation has been performed may be given to the dimming circuit 40 from the outside of the lighting power supply device.

The power supply device for lighting according to the present invention has an effect that the occurrence of light skipping can be suppressed at the time of fading out, and is mainly useful for realizing a natural change in the amount of light in the lighting device.

10 Light source 20 Power conversion circuit 30 Phase detection circuit 40 Dimming circuit 50 Control circuit

Claims (3)

It is a power supply device compatible with the phase control method for lighting using LEDs as a light source.
A control circuit that detects the phase of AC power that has undergone phase control and generates a dimming signal that indicates the dimming level of the light source according to the detected phase.
It is provided with a power conversion circuit that converts the AC power into DC power corresponding to the dimming level indicated by the dimming signal and supplies it to the light source.
The control circuit is
It has a predetermined delay time in the generation of the dimming signal, and has a predetermined delay time.
In the fade-out control that gradually lowers the dimming level, the dimming level indicated by the dimming signal reaches the dimming lower limit value before the light source is turned off due to the decrease in the AC power. A power supply for lighting that adjusts the optical signal. In the lighting power supply device according to claim 1,
The control circuit is
A phase detection circuit that detects the phase of the AC power and generates a phase detection signal indicating the detected phase value.
A power supply device for lighting, comprising: a dimming circuit that receives the phase detection signal and generates the dimming signal according to the phase value indicated by the phase detection signal. In the lighting power supply device according to claim 2.
The dimming circuit
From the time change of the phase value, the fade time required until the end of the fade-out is obtained.
A power supply device for lighting, characterized in that the dimming signal is adjusted so that the dimming level indicated by the dimming signal reaches a dimming lower limit value before the fade time elapses.

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