JP2023100421A - Illumination device - Google Patents

Abstract

To provide an illumination device which can realize natural lighting control without an overshoot of a current flowing in a light source in a case where a short fading time is set for a lighting control rate change amount.SOLUTION: An illumination device according to the present disclosure comprises: a light source; and a control device which controls the light source. The control device includes a storage unit and a control circuit. The storage unit stores a lighting control command value and a fading time setting value designated by a user. The control circuit is configured to execute: processing of deciding fading time restriction on the basis of the lighting control command value stored in the storage unit; processing of comparing the fading time setting value with the fading time restriction; and processing of deciding the longer time in the comparison as the fading time of controlling the light source.SELECTED DRAWING: Figure 2

Description

FIELD OF THE DISCLOSURE The present disclosure relates to lighting devices that use fade time settings to vary the dimming rate of a light source.

Patent Literature 1 discloses a lighting system that achieves continuous dimming based on a user's operation. Since the lighting equipment can only perform continuous dimming for a predetermined period of time, when a long fade time is set with respect to the predetermined period of time, there is a problem that stepwise and unnatural dimming occurs. Therefore, when a fade time longer than a predetermined time is set, continuous and natural dimming is achieved by creating a fade command that divides the fade time and the change width of the dimming rate.

Japanese Patent No. 6478152

However, the above method achieves good dimming when a long fade time is set for the amount of change in the dimming rate of the lighting fixture, but when a short fade time is set, the current flowing through the light source temporarily decreases. There was a problem of unnatural dimming due to overshooting.

In order to solve the above-mentioned problem, the present disclosure provides a lighting device capable of realizing natural dimming without overshooting the current flowing through the light source even when a short fade time is set for the amount of change in the dimming rate. intended to

An aspect of the present disclosure includes a light source and a control device that controls the light source, the control device has a storage unit and a control circuit, and the storage unit stores a dimming command value and a fade time setting value specified by a user. , the control circuit determines a fade time limit based on the dimming command value stored in the storage unit, compares the fade time set value and the fade time limit, and sets the longer time in the comparison to the light source. and determining the fade time to control the lighting device.

According to the aspect of the present disclosure, even when a short fade time is set with respect to the amount of change in the dimming rate of the lighting device, the current flowing through the light source does not overshoot, and natural dimming can be achieved.

1 is a circuit diagram according to Embodiment 1 of the present disclosure; FIG. 4 is a flowchart for explaining processing of the control device according to Embodiment 1 of the present disclosure; 7 is a graph comparing suitable fade times with respect to dimming rate variations according to Embodiment 1 of the present disclosure. 7 is a graph showing the relationship between dimming rate change amount and fade time limit according to Embodiment 1 of the present disclosure.

Embodiment 1
FIG. 1 is a circuit diagram according to Embodiment 1 of the present disclosure. The LED lighting device 100 comprises a dimmer 61 with a panel. The dimmer 61 transmits the dimming command value and fade time set value input by the user to the lighting device 12 . The lighting device 12 controls the LED module 11 having a plurality of LEDs according to the received information. In Embodiment 1, a lighting device using LEDs as light sources is shown, but other types of light sources may be used.

The lighting device 12 has an input filter circuit 1 . The input filter circuit 1 includes a fuse 25 for overcurrent protection, an AC capacitor 26, and a diode bridge 27 for converting AC to DC. The output of the diode bridge 27 has a high potential side connected to the DC power supply circuit 3 and a low potential side connected to a grounding terminal.

The lighting device 12 also has an input voltage detection circuit 2 . The input voltage detection circuit 2 is composed of a resistor 21 and a resistor 22 connected in series. The input voltage detection circuit 2 is connected in parallel with the capacitor 31 included in the DC power supply circuit 3 . The divided voltage value of the resistors 21 and 22 is transmitted to the control device 50 so that the control device 50 detects the input voltage.

Furthermore, the lighting device 12 has a DC power supply circuit 3 . The DC power supply circuit 3 converts the power supplied from the commercial power supply into a voltage suitable for the buck converter circuit 4 . In the DC power supply circuit 3 , the output of the diode bridge 27 is connected in parallel with the capacitor 31 . One end of the inductor 33 is connected to the positive terminal of the capacitor 31, and the negative terminal of the capacitor 31 is connected to the ground terminal. The other end of the inductor 33 is connected to the first terminal of the switching element 32 and the anode of the diode 34 . The cathode of the diode 34 is connected to the positive electrode of an electrolytic capacitor 35, and the negative electrode of the electrolytic capacitor 35 is connected to a grounding terminal.

The switching element 32 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). When the switching element 32 is a MOSFET, the first terminal is the drain terminal, the second terminal is the source terminal, and the control terminal is the gate terminal. The switching element 32 has a first terminal connected to the inductor 33 , a second terminal connected to a grounding terminal, and a control terminal connected to the control circuit 30 .

The control circuit 30 is a driver for switching control. The control circuit 30 receives a signal from the control device 50 based on the output voltage of the DC power supply circuit 3 and drives the switching element 32 .

A resistor 36 and a resistor 37 are provided at the output end of the DC power supply circuit 3 and used to detect the output voltage of the DC power supply circuit 3 . When the divided voltage is input, the controller 50 turns on and off the switching element 32 so that the output voltage of the DC power supply circuit 3 is constant.

The lighting device 12 also has a buck converter circuit 4 . In the buck converter circuit 4 , the first terminal of the switching element 41 is connected to the positive terminal of the electrolytic capacitor 35 of the DC power supply circuit 3 , and the second terminal of the switching element 41 is connected to the cathode of the diode 42 and the positive terminal of the capacitor 43 . One end of the sense resistor 44 is connected to the negative electrode of the capacitor 43 , and a grounding terminal is connected to the other end of the sense resistor 44 and the anode of the diode 42 .

The switching element 41 is, for example, a MOSFET, in which case the first terminal is the drain terminal, the second terminal is the source terminal, and the control terminal is the gate terminal. The switching element 41 has a first terminal connected to the positive electrode of the electrolytic capacitor 35 , a second terminal connected to a grounding terminal, and a control terminal connected to the control circuit 40 .

A sense resistor 44 is used to detect the LED current flowing through the LED module 11 . First, a detection voltage corresponding to the LED current from the sense resistor 44 is input to the control circuit 40 . Based on the detected voltage, the control circuit 40 turns on and off the switching element 41 so that the current flowing through the LED module 11 becomes a constant current. The voltage from the sense resistor 44 is also input to the control device 50, and the control device 50 detects a current abnormality based on this detected voltage.

A resistor 45 and a resistor 46 are provided at the output terminal of the buck converter circuit 4 and used for voltage detection of the LED module 11 . When the divided voltage is input to the control device 50, the control device 50 detects whether or not the LED module 11 is connected or abnormal voltage based on the detected voltage.

The control device 50 can be configured by a known microcomputer provided as a digital power supply control device, or can be configured by an arithmetic device such as a DSP (Digital Signal Processor). For example, the control device 50 in FIG. 1 includes a storage section, a processing device, an A/D conversion circuit, and a control circuit.

The storage unit has a non-volatile memory and stores a calculation program to be executed by the processor and various data used for the calculation. The following voltage values are input from the inside of the circuit to the storage unit. (1) voltage corresponding to the output voltage of the DC power supply circuit 3 divided by the resistors 36 and 37, (2) voltage corresponding to the output voltage of the DC power supply circuit 3 divided by the resistors 45 and 46, ( 3) A voltage corresponding to the voltage obtained by rectifying the AC power voltage divided by the resistors 21 and 22 . These voltage values are converted into digital values by an A/D conversion circuit, and arithmetic processing is performed by a processing unit using the digital values. In addition to writing and reading data from the outside of the circuit, it is also involved in setting the fade time of this embodiment, as will be described later.

The control circuit outputs a PWM signal that controls the control circuit 30 and the control circuit 40 . Further, the constant voltage control performed by the control device 50 by turning on and off the switching element 32 is adjusted so as to match the target voltage set in advance in the storage section. On the other hand, the constant current control performed by the control device 50 by turning on and off the switching element 41 is adjusted based on the input value from the dimmer 61 . First, when a dimming command value and a fade time set value are inputted from the dimmer 61 through the dimming interface circuit 62, a target current value is determined based on this dimming command value. Then, on/off of the switching element 41 is adjusted based on the current detected by the sense resistor 44 so that the current flowing through the LED module 11 matches this target current value. Note that the time required for transition from the current dimming rate to the target dimming rate is determined by the fade time setting method described later based on the fade time set value input above.

A method of setting the fade time in this embodiment will be described. If a short fade time is set with respect to the amount of change in the dimming rate, the current flowing through the LED module 11 temporarily overshoots, which poses a problem that the light source appears to be flashing. This overshoot occurs because the constant current feedback provided by the controller 50 cannot follow the fade time. In other words, this overshoot can be prevented by speeding up the response of the constant current feedback.

However, if the response of the constant current feedback is increased, the frequency becomes closer to the operating frequency, so there is no phase margin, and the operation tends to become unstable. In addition, flickering tends to occur because the display is sensitive to external noise and the like. Due to the above, there is a limit to speeding up the response.

Therefore, in the present disclosure, the fade time limit function is used to limit the fade time without changing the responsiveness of the constant current feedback. The fade time limit is a time limit that is individually set for each lighting device 12, and if a time shorter than this time is used as the fade time, the possibility of current overshooting increases. For example, when an extremely short fade time is transmitted from the dimmer 61, the fade time limit function converts the fade time to a longer fade time than a certain period so that the current flowing through the LED module 11 does not overshoot. It is a thing.

Let the above fade time limit be Fade_Time_Lim. Assuming that the dimming command value is DIM_Goal and the current dimming rate is DIM_Now, their relationships are as follows.

Fade_Time_Lim=R×|DIM_Goal−DIM_Now| (Formula 1)

Here, the coefficient R is a variable determined by factors such as the constant current feedback setting value of the lighting device 12 . As an example, there is a method of making a graph of the current value when changing the dimming rate change width and fade time of the lighting device 12 in advance, and determining an appropriate coefficient R by looking at the waveform. In this case, the criteria for judging that the fade time is appropriate are the following three points. Some models require all three points, while others require only (1) to be sufficient. (1) the current does not exceed the rating of each part, (2) the current does not exceed the value at full light, and (3) it operates smoothly.

FIG. 2 is a flowchart illustrating processing of the control device according to Embodiment 1 of the present disclosure. The control device 50 determines the fade time of the lighting device 12 according to the flow chart shown in FIG.

First, controller 50 receives DIM_Goal and Fade_Time from the dimmer at step 100 . Fade_Time here refers to the fade time set value sent from the dimmer 61 . This DIM_Goal and Fade_Time are stored in the storage section of the control device 50 .

Next, the controller 50 calculates Fade_Time_Lim at step 102 . Fade_Time_Lim can be calculated based on DIM_Goal and coefficient R. DIM_Goal is stored in the memory of controller 50 at step 100 . The coefficient R is determined in advance for each lighting device and has been input from the dimmer 61 or stored in the storage section of the control device 50 from the beginning.

Subsequently, at step 104, Fade_Time and Fade_Time_Lim are compared. If Fade_Time is longer, go to step 106 to determine Fade_Time as the actual fade time. If Fade_Time is shorter, proceed to step 108 to determine Fade_Time_Lim to be the actual fade time.

By the above processing, the actual fade time is limited to a time longer than the fade time limit, that is, the fixed time at which the possibility of overshooting increases. Therefore, even if the fade time set value transmitted from the dimmer 61 is extremely short, overshoot can be prevented without changing the responsiveness of the constant current feedback or adding components.

FIG. 3 is a graph comparing appropriate fade times with respect to dimming rate variations according to Embodiment 1 of the present disclosure. The horizontal axis indicates time. The vertical axis indicates the current flowing through the LED and the dimming rate that fluctuates accordingly.

The three graphs differ in the amount of change in the light control rate, and the change amounts become smaller in the order of the light control rate change amounts A, B, and C. FIG. Appropriate fade times that do not cause overshoot for each amount of change are the fade time limits a, b, and c.

As mentioned above, the lighting device of the present disclosure controls the dimming rate by constant current feedback. Therefore, the current when changing the dimming rate tends to overshoot the greater the amount of change, and less likely to overshoot the smaller the amount of change. That is, when the amount of change is large, such as the amount of change in dimming rate A, it is necessary to use a longer fade time limit a. be enough.

The presence or absence of overshoot in the present disclosure is determined by sensory evaluation. The three graphs in FIG. 3 differ in the amplitude of the overshoot, but all of them are judged to be within an appropriate range by the sensory evaluation.

FIG. 4 is a graph showing the relationship between the dimming rate change amount and the fade time limit according to Embodiment 1 of the present disclosure. As described above, due to the nature of constant current feedback, there is a positive correlation between the amount of dimming rate change and the length of the fade time limit. In the case of the first embodiment, the horizontal axis represents the fade time limit, and the vertical axis represents the amount of change in the dimming rate, resulting in a graph of a linear function. If there are factors other than constant current feedback that cause overshoot, other graphs may be used.

11 LED module 50 control device 61 dimmer

Claims (3)

a light source;
A control device for controlling the light source,
The control device has a storage unit and a control circuit,
The storage unit
storing the dimming command value and the fade time setting value specified by the user;
The control circuit is
a process of calculating a fade time limit based on the dimming command value stored in the storage unit;
a process of comparing the fade time setting and the fade time limit;
determining the longer time in the comparison as a fade time for controlling the light source. 2. The illumination device of claim 1, wherein the fade time limit is positively correlated with a dimming rate change amount. The dimming command value and the fade time setting value are
3. A lighting device according to claim 1 or 2, transmitted from a user-operated dimmer.

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