JP7848616B2 - Dimming controllers, lighting fixtures, and lighting control systems - Google Patents

Description

This disclosure relates to a dimming controller for controlling the color temperature of a lighting fixture, a lighting fixture, and a lighting control system.

Patent Document 1 discloses a dimming control system that simultaneously controls the brightness and color temperature of a lighting fixture. This system utilizes PWM (pulse width modulation) signals transmitted and received via the same signal line. The duty cycle of the PWM signal indicates the dimming rate of the first load, and the frequency indicates the dimming rate of the second load.

Patent No. 5744261

In the dimming control system of Patent Document 1, the lighting fixture controls the dimming rates of two loads with different color temperatures to express a mixed color temperature. However, there was a problem that when the dimming rate of the lighting fixture was low, the number of color temperatures that could be expressed was limited. The dimming rate of the lighting fixture is expressed as the sum of the dimming rates of the two loads. For example, if the duty cycle and period resolution of the PWM signal is 100 steps, that is, if the dimming rates of the two loads can be controlled in 1% increments, consider the combinations of dimming rates of the two loads to make the dimming rate of the lighting fixture 10%. There are 11 such combinations: (0%, 10%), (1%, 9%), (2%, 8%), ... (8%, 2%), (9%, 1%), (10%, 0%). Thus, in Patent Document 1, the lower the dimming rate, the fewer combinations of dimming rates of the two loads there are, and therefore only a limited number of color temperatures could be expressed. To address this problem, it's possible to increase the number of color temperature combinations by, for example, raising the duty cycle and period resolution of the PWM signal to 200 steps and controlling the dimming rate of the two loads in 0.5% increments. However, this requires the use of high-performance electronic components or signal lines, which leads to increased costs for lighting control equipment or lighting fixtures.

This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a dimming controller and lighting fixture that can express a wider range of color temperatures without increasing the resolution of the PWM signal, even when the dimming rate of the lighting fixture is low.

This disclosure was made to solve the problems described above, and its purpose is to provide a lighting control system that can express a wider range of color temperatures without increasing the resolution of the PWM signal, even when the dimming rate of the lighting fixture is low.

A first aspect of this disclosure is a dimming controller for use with a lighting fixture having two loads having different color temperatures, in order to achieve the above objective,
A process to determine whether the dimming rate to be achieved is greater than or equal to the threshold,
When the dimming rate is less than or equal to the TH threshold,
A first temporary power calculation process that calculates the first temporary power using the value obtained by adding an offset to the dimming rate and the color ratio of the first load to be realized,
A second temporary power calculation process that calculates the second temporary power using the value obtained by adding the offset to the dimming rate and the color ratio of the second load to be realized,
A first signal transmission process that transmits a signal containing information on the first temporary power and the second temporary power,
The process that executes,
If the dimming rate is greater than the threshold,
A third temporary power calculation process calculates the first temporary power using the value obtained by subtracting the offset from the dimming rate and the color ratio of the first load,
A fourth temporary power calculation process calculates the second temporary power using the value obtained by subtracting the offset from the dimming rate and the color ratio of the second load,
A second signal transmission process transmits a signal containing information of the first temporary power calculated from the third temporary power calculation process and the second temporary power calculated from the fourth temporary power calculation process.
The process that executes,
It is desirable to configure it to perform this action .

Furthermore, a second aspect of this disclosure is a lighting fixture comprising two loads having different color temperatures,
The signal transmitted from the dimming controller is received and the signal reception processing is performed.
A restoration process to reconstruct the first and second temporary powers from the aforementioned signals and to determine the restored first temporary power and restored second temporary power,
A dimming rate reproduction process that reproduces the dimming rate by removing the offset from the sum of the restored first temporary power and the restored second temporary power,
Based on the restored first temporary power and the restored second temporary power, a first color ratio reproduction process is performed to reproduce the color ratio of the first load,
Based on the restored first temporary power and the restored second temporary power, a second color ratio reproduction process is performed to reproduce the color ratio of the second load,
A first dimming rate calculation process calculates the dimming rate of the first load from the dimming rate reproduced by the dimming rate reproduction process and the color ratio of the first load reproduced by the first color ratio reproduction process.
A second dimming rate calculation process calculates the dimming rate of the second load from the dimming rate reproduced by the dimming rate reproduction process and the color ratio of the second load reproduced by the second color ratio reproduction process,
The driving power of the first load is updated according to the dimming rate of the first load.
A drive power update process that updates the drive power of the second load based on the dimming ratio of the second load,
It is desirable to configure it to perform this action.

Furthermore, a third aspect of this disclosure is preferably a lighting control system comprising the dimming controller described in the first aspect and the lighting fixture described in the second aspect.

According to the first or second embodiment, it is possible to provide a dimming controller and lighting fixture that can express a wider range of color temperatures without increasing the resolution of the PWM signal, even when the dimming rate of the lighting fixture is low.

According to the third embodiment, it is possible to provide a lighting control system that can express a wider range of color temperatures without increasing the resolution of the PWM signal, even when the dimming rate of the lighting fixture is low.

This is a block diagram of the lighting control system according to Embodiment 1. This is a block diagram showing the configuration of the dimming controller according to Embodiment 1. This is a block diagram showing the configuration of a lighting fixture according to Embodiment 1. This is a waveform diagram of a PWM signal according to Embodiment 1. This flowchart shows the operation of the dimming controller when it is instructed to change the dimming rate and color temperature, up to the point when the dimming controller transmits a PWM signal, according to Embodiment 1. (a) A graph showing the relationship between the color ratio and color temperature of the first load, and (b) A graph showing the relationship between the color ratio and color temperature of the second load, according to Embodiment 1. This figure illustrates the number of S_DUTY and S_CYCLE values, and their combinations, for a comparative example where the desired dimming rate is 10% and the offset is 0. This figure illustrates the number of S_DUTY and S_CYCLE values, and their combinations, in the case of Embodiment 1, where the desired dimming rate is 10% and the offset is 50%. The first embodiment shows (a) a graph showing the relationship between the duty cycle of the PWM signal and S_DUTY, and (b) a graph showing the relationship between the period of the PWM signal and S_CYCLE. This figure shows the relationship between the duty cycle and period of the PWM signal and the dimming rate and color temperature of the lighting fixture when the offset is 50%, according to Embodiment 1. This flowchart shows the operation according to Embodiment 1, from the time the lighting fixture receives a PWM signal until the drive power of the first load and the drive power of the second load are updated. This is a block diagram of the lighting control system according to Embodiment 2. This is a block diagram showing the configuration of the conversion unit according to Embodiment 2.

A lighting control system according to an embodiment of this disclosure will be described with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and repetition of the description may be omitted.

Embodiment 1
Figure 1 is a block diagram of a lighting control system 100. This lighting control system 100 comprises a dimming controller 10, lighting fixtures 20, and a setting device 30. The setting device 30 is used by an operator to operate or set the dimming controller 10. The setting device 30 communicates with the dimming controller 10 using infrared communication 50. The dimming controller 10 communicates with the lighting fixtures 20 via a signal line 40.

Figure 2 is a block diagram showing the configuration of the dimming controller 10. The dimming controller 10 includes a control unit 11, a communication output unit 12, an infrared communication unit 13, a human detection sensor unit 14, a brightness sensor unit 15, an LED status display unit 16, and a power supply unit 17. The control unit 11 performs calculations necessary to realize the functions of the dimming controller 10 and calculations necessary for controlling the lighting fixture 20.

The communication output unit 12 transmits PWM signals via the signal line 40. Here, the communication output unit 12 may output multiple different PWM signals via multiple signal lines 40. The infrared communication unit 13 performs infrared communication 50 with the setting device 30.

The human detection sensor unit 14 detects the presence or absence of a person and transmits the detected information to the control unit 11. The brightness sensor unit 15 detects the brightness and transmits the detected information to the control unit 11. Based on the information received from the infrared communication unit 13, the human detection sensor unit 14, and the brightness sensor unit 15, the control unit 11 controls the lighting fixture 20 via the communication output unit 12.

The LED status display unit 16 displays the status of, for example, the dimming controller 10 using LEDs. The control unit 11 controls the LED status display unit 16.

The power supply unit 17 provides power to each part of the dimming controller 10.

Figure 3 is a block diagram showing the configuration of the lighting fixture 20. The lighting fixture 20 includes a control unit 21, a communication input unit 22, a first load light source unit 23, a second load light source unit 24, a light source control unit 25, and a power supply unit 26. The control unit 21 performs calculations to realize the functions of the lighting fixture 20. The control unit 21 also provides the light source control unit 25 with the information necessary to control the first load light source unit 23 and the second load light source unit 24.

The communication input unit 22 receives a PWM signal transmitted from the dimming controller 10 via the signal line 40. The control unit 21 controls each part of the lighting fixture 20 according to the PWM signal received by the communication input unit 22.

The light source control unit 25 controls the first load light source unit 23 and the second load light source unit 24. The light source control unit 25 controls the power supplied to the first load light source unit 23 and the second load light source unit 24, for example, in response to a control signal from the control unit 21. The first load light source unit 23 and the second load light source unit 24 each have light sources with different color temperatures. The light sources are, for example, light-emitting elements such as LEDs. The power supply unit 26 provides power to each part of the lighting fixture 20.

Figure 4 shows the waveform of the PWM signal transmitted and received on signal line 40. Th is the time duration during which the voltage VT is at a high level within one cycle of the PWM signal. The duty cycle (%) of the PWM signal is calculated as Th/T using the period T and Th. If the duty cycle is 100% or 0%, the receiving side cannot recognize the period T. Similarly, if the period is 0, the duty cycle cannot be recognized. Therefore, the PWM signal should be used within the duty cycle and period ranges where 0% < duty cycle < 100% and 0 < period.

Figure 5 is a flowchart showing the operation from when the dimming controller 10 is instructed to change the dimming rate and color temperature until it transmits a PWM signal. Hereafter, the first load light source unit 23 will be simply referred to as the first load 23, and the second load light source unit 24 will be simply referred to as the second load 24.

First, the dimming controller 10 is activated (step 120 in Figure 5). Furthermore, the dimming controller 10 determines whether or not an instruction has been given to change the dimming rate and color temperature from the current set values to a different, desired value (step 122). If an instruction for change is received, the dimming controller converts the desired color temperature into a color ratio (step 124). The color ratio is the ratio of the color temperatures of the first load 23 and the second load 24, which have different color temperatures, used to represent a certain mixed color temperature. The following equations (Equation 1) and (Equation 2) are used to calculate the color ratio.

Color ratio (%) of the first load 23 = 100 - (color temperature - color temperature of the first load 23) / (color temperature of the second load 24 - color temperature of the first load 23) * 100 (Equation 1)
Color ratio (%) of the second load 24 = (Color temperature - Color temperature of the first load 23) / (Color temperature of the second load 24 - Color temperature of the first load 23) * 100 (Equation 2)

However, assume that the color temperature of the first load 23 ≤ color temperature ≤ color temperature of the second load 24. Furthermore, the following relationships are obtained from (Equation 1) and (Equation 2).

Color ratio of the first load (23) + Color ratio of the second load (24) = 100% (Equation 3)

For example, consider a case where the color temperature of the first load 23 is 3000K, the color temperature of the second load 24 is 5000K, and the dimming controller 10 is instructed to change the color temperature to 3200K. In this case, from (Equation 1), the color ratio of the first load 23 is 90%, and from (Equation 2), the color ratio of the second load 24 is 10%.

Figure 6(a) is a graph showing the relationship between the color ratio and color temperature of the first load 23. Figure 6(b) is a graph showing the relationship between the color ratio and color temperature of the second load 24. However, in Figures 6(a) and (b), the color temperature of the first load 23 ≤ color temperature ≤ color temperature of the second load 24.

Next, the dimming controller 10 converts the dimming rate given as the desired value and the color ratio obtained in step 124 into a duty cycle step S_DUTY and a period step S_CYCLE (step 126 in Figure 5). A dimming rate offset is used here. Using a threshold = (100% - offset) as the boundary, S_DUTY and S_CYCLE are calculated using the following formulas.

If 0% ≤ dimming rate ≤ (100% - offset),
S_DUTY = Color ratio of the second load 24 / 100 * (Dimming rate + Offset) (Equation 4)
S_CYCLE = Color ratio of the first load 23 / 100 * (Dimming rate + Offset) (Equation 5)

(100% - Offset) < Dimming Rate ≤ 100%,
S_DUTY = 100 - Color ratio of the first load 23 / 100 * (200 - Dimming rate - Offset) (Equation 6)
S_CYCLE = 100 - Color ratio of the second load 24 / 100 * (200 - Dimming rate - Offset) (Equation 7)

For example, if the dimming offset is set to 50%, S_DUTY and S_CYCLE are calculated using the following formula, with a threshold of 50% as the boundary.

If 0% ≤ dimming rate ≤ 50%,
S_DUTY = Color ratio of the second load 24 / 100 * (Dimming rate + 50) (Equation 8)
S_CYCLE = Color ratio of the first load 23 / 100 * (Dimming rate + 50) (Equation 9)

If 50% < dimming rate ≤ 100%,
S_DUTY = 100 - Color ratio of the first load 23 / 100 * (200 - Dimming rate - 50) (Equation 10)
S_CYCLE = 100 - Color ratio of second load 24 / 100 * (200 - Dimming rate - 50) (Equation 11)

From the relationship between (Equation 4) and (Equation 5), the sum of S_DUTY and S_CYCLE can be expressed using the dimming rate and color ratio by the following relationship:

If 0% ≤ dimming rate ≤ (100% - offset),
S_DUTY + S_CYCLE = Dimming Rate + Offset (Equation 12)

Similarly, from the relationship between (Equation 6) and (Equation 7), the following relationship can be obtained.

(100% - Offset) < Dimming Rate ≤ 100%,
S_DUTY + S_CYCLE = Dimming Rate + Offset (Equation 13)

Furthermore, the following relationship can be obtained from (Equation 4) and (Equation 5).
If 0% ≤ dimming rate ≤ (100% - offset),
S_DUTY : S_CYCLE = Color ratio of second load 24 : Color ratio of first load 23 (Equation 14)

On the other hand, the following relationship can be obtained from (Equation 6) and (Equation 7).
(100% - Offset) < Dimming Rate ≤ 100%,
(100 - S_DUTY) : (100 - S_CYCLE) = Color ratio of first load 23 : Color ratio of second load 24 (Equation 15)

Here, we will first explain the case where there is no offset as a comparative example. Figure 7 is a diagram illustrating the number of S_DUTY and S_CYCLE values and their combinations when the desired dimming rate is 10% and the offset is 0. In this comparative example, since 0% ≤ dimming rate ≤ (100% - offset), (Equation 14) is applied, and the ratio of S_DUTY to S_CYCLE is equal to the ratio of the color ratio of the second load 24 to the color ratio of the first load 23. Also, since the offset is 0, from (Equation 12), the sum of S_DUTY and S_CYCLE is equal to the dimming rate. That is, S_DUTY and S_CYCLE are the color ratios of the second load 24 and the first load 23 in relation to the dimming rate, respectively. Here, if the duty cycle and period resolution of the PWM signal are 100 steps, S_DUTY and S_CYCLE can be controlled in units of 1%. Therefore, there are 11 possible combinations of S_DUTY and S_CYCLE values: (0%, 10%), (1%, 9%), (2%, 8%)... (8%, 2%), (9%, 1%), (10%, 0%).

Next, the effect of the offset used in this embodiment will be explained. Figure 8 illustrates the number of S_DUTY, S_CYCLE, and their combinations when the desired dimming rate is 10% and the offset is 50%. In this case, as with the comparative example, 0% ≤ dimming rate ≤ (100% - offset). However, from (Equation 12), the sum of S_DUTY and S_CYCLE is equal to the dimming rate plus the offset. Therefore, S_DUTY and S_CYCLE represent the color ratio of the second load 24 and the first load 23 in (dimming rate + offset). Here again, assuming the same resolution as the comparative example, the combinations of S_DUTY and S_CYCLE values are (0%, 60%), (1%, 59%), (2%, 58%)...(58%, 2%), (59%, 1%), (60%, 0%), totaling 61 combinations.

The mixed color temperature of the lighting fixture 20 is expressed using a combination of S_DUTY and S_CYCLE. In this embodiment, although the resolution is the same as in the comparative example, the introduction of an offset allows for the generation of more S_DUTY and S_CYCLE combinations. That is, this embodiment provides a wider range of color temperature options.

Next, the dimming controller 10 converts S_DUTY and S_CYCLE, obtained in step 126, into the duty cycle and period of the PWM signal (step 128 in Figure 5). Figure 9(a) is a graph showing the relationship between the duty cycle and S_DUTY of the PWM signal. Figure 9(b) is a graph showing the relationship between the period and S_CYCLE of the PWM signal. As shown in Figure 9(a), in the duty cycle range of 5% to 90%, S_DUTY and the duty cycle have a linear relationship, allowing for a one-to-one correspondence. As shown in Figure 9(b), in the period range of 10ms to 1ms, S_CYCLE and the period also have a linear relationship. Therefore, for example, if S_DUTY obtained in step 126 is Ya and S_CYCLE is Yb, it can be associated with a PWM signal having a duty cycle of Xa and a period of Xb.

As shown in Figure 9(a), the one-to-one correspondence between S_DUTY and the duty cycle is defined for duty cycles ranging from 5% to 90%. Similarly, as shown in Figure 9(b), the one-to-one correspondence between S_CYCLE and the period is defined for periods ranging from 10ms to 1ms. Therefore, if S_DUTY or S_CYCLE exceeds 100, a one-to-one correspondence cannot be achieved using only the defined duty cycle and period ranges.

Here, when the dimming rate is equal to the threshold = (100% - offset), S_DUTY and S_CYCLE can take a maximum value of 100. This is evident when we assume the dimming rate is equal to the threshold and calculate S_DUTY and S_CYCLE using (Equation 4) and (Equation 5), respectively. Furthermore, when the dimming rate becomes even larger and exceeds the threshold, using (Equation 4) and (Equation 5), the maximum values of S_DUTY and S_CYCLE will exceed 100.

Therefore, in this embodiment, when the dimming rate is greater than the threshold, S_DUTY and S_CYCLE are calculated using (Equation 6) and (Equation 7), respectively. In (Equation 6) and (Equation 7), the calculation formulas are set so that S_DUTY and S_CYCLE do not exceed 100. By performing this case distinction, even when the dimming rate is greater than the threshold, it becomes unnecessary to widen the usable range of the duty cycle and period of the PWM signal.

Finally, the dimming controller 10 performs a process to transmit the updated PWM signal, which has a waveform with the duty cycle and period determined in step 128 (Figure 5, step 130).

Figure 10 is a graph showing the relationship between the duty cycle and period of the PWM signal, and the dimming rate and color ratio when the offset is 50%. The dashed line 140 represents the portion where the color ratio of the second load 24 is 100%. The dotted line 142 represents the portion where the color ratio of the first load 23 is 100%. The solid line 144 represents the portion where both the color ratio of the first load 23 and the color ratio of the second load 24 are 50%. The dashed-dotted line 146 represents the portion with a dimming rate of 0%, the dashed-dotted line 148 represents the portion with a dimming rate of 50%, and the dashed-dotted line 150 represents the portion with a dimming rate of 100%.

Figure 11 is a flowchart showing the operation from the time the lighting fixture 20 receives a PWM signal until the drive power of the first load 23 and the drive power of the second load 24 are updated.

First, the lighting fixture 20 is activated (step 160 in Figure 11). Next, the lighting fixture 20 receives a PWM signal (step 162). Then, the lighting fixture 20 reads the time Th and period T for when the voltage is High from the received PWM signal, and calculates the duty cycle and period (step 164).

Furthermore, the lighting fixture 20 reconstructs S_DUTY and S_CYCLE from the duty cycle and period obtained in step 164 (step 166 in Figure 11). Figures 9(a) and 9(b) are used here. For example, if the duty cycle of the received PWM signal is Xa and the period is Xb, then S_DUTY can be reconstructed as Ya and S_CYCLE as Yb.

Next, the lighting fixture 20 reproduces the dimming rate from S_DUTY and S_CYCLE restored in step 166 (step 168 in Figure 11). There, the dimming controller 10 calculates the following formula using the offset values used to calculate S_DUTY and S_CYCLE.

When Offset ≤ (S_DUTY + S_CYCLE) ≤ 100%, the dimming rate = (S_DUTY + S_CYCLE - Offset) (Equation 16)

If 100% < (S_DUTY + S_CYCLE) ≤ (100% + offset), then the dimming rate = (S_DUTY + S_CYCLE - offset) (Equation 17)

Since S_DUTY and S_CYCLE contain offset values, the offset is removed in (Equation 16) or (Equation 17). This allows the desired value of the original dimming rate to be reproduced.

Here, the calculation formulas for S_DUTY and S_CYCLE in the dimming controller 10 had two distinct cases: 0% ≤ dimming rate ≤ (100% - offset) and (100% - offset) < dimming rate ≤ 100%. For the lighting fixture 20 to remove the offset from S_DUTY and S_CYCLE, the lighting fixture 20 needs to determine which case the values were calculated under. The conditional expression used for this determination is based on the sum of S_DUTY and S_CYCLE.

If offset ≤ (S_DUTY + S_CYCLE) ≤ 100%, it is determined that the dimming controller 10 calculated S_DUTY and S_CYCLE based on the case where 0% ≤ dimming rate ≤ (100% - offset). That is, it is determined that S_DUTY and S_CYCLE were calculated using (Equation 4) and (Equation 5). On the other hand, if 100% < (S_DUTY + S_CYCLE) ≤ (100% + offset), it is determined that the dimming controller 10 calculated S_DUTY and S_CYCLE based on the case where (100% - offset) < dimming rate ≤ 100%. That is, it is determined that S_DUTY and S_CYCLE were calculated using (Equation 6) and (Equation 7). In this way, the case distinctions within the dimming controller 10 can be identified, and the lighting fixture 20 can remove the offset in an appropriate manner according to each case.

Next, the lighting fixture 20 reproduces the color ratios of the first load 23 and the second load 24 from the S_DUTY and S_CYCLE restored in step 166 (step 170 in Figure 11). At this stage, the following formula is calculated:

When offset ≤ (S_DUTY + S_CYCLE) ≤ 100%, the color ratio of the first load 23 = S_CYCLE / (S_DUTY + S_CYCLE) (Equation 18)
Color ratio of second load 24 = S_DUTY / (S_DUTY + S_CYCLE) (Formula 19)

When 100% < (S_DUTY + S_CYCLE) ≤ (100% + offset), the color ratio of the first load 23 = (100 - S_DUTY) / ((100 - S_DUTY) + (100 - S_CYCLE)) (Equation 20)
Color ratio of the second load 24 = (100 - S_CYCLE) / ((100 - S_DUTY) + (100 - S_CYCLE)) (Equation 21)

Next, the lighting fixture 20 calculates the dimming rates of the first load 23 and the second load 24 (step 172 in Figure 11). Here, using the dimming rates reproduced in step 168 and the color ratios of the first load 23 and second load 24 reproduced in step 170, the following formula is calculated.

When offset ≤ (S_DUTY + S_CYCLE) ≤ 100%, the dimming rate of the first load 23 = dimming rate * color ratio of the first load 23 = (S_DUTY + S_CYCLE - offset) * S_CYCLE / (S_DUTY + S_CYCLE) (Equation 22)
Dimming rate of the second load 24 = Dimming rate * Color ratio of the second load 24 = (S_DUTY + S_CYCLE - Offset) * S_DUTY / (S_DUTY + S_CYCLE) (Equation 23)

If 100% < (S_DUTY + S_CYCLE) ≤ (100% + offset), then the dimming rate of the first load 23 = dimming rate * the color ratio of the first load 23 = (S_DUTY + S_CYCLE - offset) * (100 - S_DUTY) / ((100 - S_DUTY) + (100 - S_CYCLE)) (Equation 24)
Dimming rate of the second load 24 = Dimming rate * Color ratio of the second load 24 = (S_DUTY + S_CYCLE - Offset) * (100 - S_CYCLE) / ((100 - S_DUTY) + (100 - S_CYCLE)) (Equation 25)

For example, if the dimming offset is 50%, the dimming rates of the first load 23 and the second load 24 are expressed by the following formulas.

When 50% ≤ (S_DUTY + S_CYCLE) ≤ 100%, the dimming rate of the first load 23 = (S_DUTY + S_CYCLE - 50%) * S_CYCLE / (S_DUTY + S_CYCLE) (Equation 26)
Dimming rate of second load 24 = (S_DUTY + S_CYCLE - 50%) * S_DUTY / (S_DUTY + S_CYCLE) (Formula 27)

When 100% < (S_DUTY + S_CYCLE) ≤ 150%, the dimming rate of the first load 23 = (S_DUTY + S_CYCLE - 50%) * (100 - S_DUTY) / ((100 - S_DUTY) + (100 - S_CYCLE)) (Equation 28)
Dimming ratio of the second load 24 = (S_DUTY + S_CYCLE - 50%) * (100 - S_CYCLE) / ((100 - S_DUTY) + (100 - S_CYCLE)) (Equation 29)

The combinations of dimming rates for the first load 23 and the second load 24, calculated from (Equations 22) and (23), or (Equations 24) and (25), are as numerous as the number of combinations of S_DUTY and S_CYCLE. As described above, in this embodiment, by using an offset, it is possible to generate more combinations of S_DUTY and S_CYCLE compared to the conventional technique. As a result, the color temperature resolution can be improved compared to the conventional technique.

Finally, the lighting fixture 20 updates the power driving the first load 23 and the second load 24 according to the dimming rates of the first load 23 and the second load 24 determined in step 172 (step 174 in Figure 11).

[Explanation of correspondence with terms used in claims]
In this embodiment, the period or duty cycle step calculated by the dimming controller 10 based on the color ratio of the first load 23 is defined as the first temporary power. That is, S_CYCLE calculated by (Equation 5) and S_DUTY calculated by (Equation 6) are defined as the first temporary power.

Similarly, the period or duty cycle step calculated by the dimming controller 10 based on the color ratio of the second load 24 is defined as the second temporary power. That is, S_DUTY calculated by (Equation 4) and S_CYCLE calculated by (Equation 7) are defined as the second temporary power.

Furthermore, the calculation process for the first temporary power using (Equation 5) is designated as the first temporary power calculation process, and the calculation process for the second temporary power using (Equation 4) is designated as the second temporary power calculation process. Also, the calculation process for the first temporary power using (Equation 6) is designated as the third temporary power calculation process, and the calculation process for the second temporary power using (Equation 7) is designated as the fourth temporary power calculation process.

When the dimming controller 10 transmits the first temporary power as a PWM signal to the lighting fixture 20, the first temporary power restored by the lighting fixture 20 from the waveform of that PWM signal is designated as the restored first temporary power.

Similarly, when the dimming controller 10 transmits the second temporary power as a PWM signal to the lighting fixture 20, the second temporary power reconstructed by the lighting fixture 20 from the waveform of that PWM signal is designated as the reconstructed second temporary power.

In this embodiment, the reproduction process by which the lighting fixture 20 reproduces the color ratio of the first load 23 is referred to as the first color ratio reproduction process. That is, the calculation process of the color ratio of the first load 23 using equations (18) and (20) is referred to as the first color ratio reproduction process.

Similarly, the reproduction process by which the lighting fixture 20 reproduces the color ratio of the second load 24 is defined as the second color ratio reproduction process. That is, the calculation process of the color ratio of the second load 24 using equations (19) and (21) is defined as the second color ratio reproduction process.

In this embodiment, the calculation process by which the lighting fixture 20 calculates the dimming rate of the first load 23 is referred to as the first dimming rate calculation process. That is, the calculation process of the dimming rate of the first load 23 using equations (22) and (24) is referred to as the first dimming rate calculation process.

Similarly, the calculation process by which the lighting fixture 20 calculates the dimming rate of the second load 24 is defined as the second dimming rate calculation process. That is, the calculation process of the dimming rate of the second load 24 using equations (23) and (25) is defined as the second dimming rate calculation process.

[Modified example of Embodiment 1]
By the way, in Embodiment 1, S_DUTY is associated with the duty cycle of the PWM signal, and S_CYCLE is associated with the period of the PWM signal. However, this relationship may be reversed. That is, S_DUTY may be associated with the period of the PWM signal, and S_CYCLE may be associated with the duty cycle of the PWM signal.

Furthermore, the correspondence between cases where the dimming rate is below the threshold (100% - offset) and cases where it is above the threshold may be reversed. That is, when the dimming rate is below the threshold, S_DUTY is associated with the duty cycle of the PWM signal, and S_CYCLE is associated with the period of the PWM signal. On the other hand, when the dimming rate is below the threshold, S_DUTY may be associated with the period of the PWM signal, and S_CYCLE may be associated with the duty cycle of the PWM signal. This is also the case in the following Embodiment 2.

Embodiment 2
Figure 12 is a block diagram of a lighting control system 200 in which a conversion unit 70 is placed between a dimming controller 10 and a lighting fixture 20. This lighting control system 200 comprises a dimming controller 10, a lighting fixture 20, a setting device 30, and a conversion unit 70. In Figure 12, the conversion unit 70 is shown as a separate device from the lighting fixture 20, but the conversion unit 70 may be located inside the lighting fixture 20.

The dimming controller 10 converts the dimming rate and color temperature into the duty cycle and period of the PWM signal and transmits it as a PWM signal to the conversion unit 70. The conversion unit 70 receives the PWM signal and calculates the dimming rates of the first load 23 and the second load 24 from its duty cycle and period. The conversion unit 70 also transmits the information of the dimming rates of the first load 23 and the second load 24 as a digital signal to the lighting fixture 20 via the signal line 60.

The lighting fixture 20 controls the dimming rate of the first load 23 and the second load 24 based on the received digital signal.

Figure 13 is a block diagram showing the configuration of the conversion unit 70. The conversion unit 70 includes a control unit 71, a communication input unit 72, a communication output unit 73, and a power supply unit 74. The control unit 71 calculates the dimming rates of the first load 23 and the second load 24 based on the PWM signal input to the communication input unit 72, and provides these values to the communication output unit 73.

The communication input unit 72 receives the PWM signal transmitted from the dimming controller 10 via the signal line 40. The communication output unit 73 outputs digital signals related to the dimming rates of the first load 23 and the second load 24 to the lighting fixture 20 via the signal line 60. The power supply unit 74 provides power to each part of the conversion unit 70.

10 Dimming controller 11 Control unit 12 Communication output unit 13 Infrared communication unit 14 Human detection sensor unit 15 Brightness sensor unit 16 LED status display unit 17 Power supply unit 20 Lighting fixture 21 Control unit 22 Communication input unit 23 First load light source unit 24 Second load light source unit 25 Light source control unit 26 Power supply unit 30 Setting device 40 Signal line 50 Infrared communication 60 Signal line 70 Conversion unit 71 Control unit 72 Communication input unit 73 Communication output unit 74 Power supply units 100, 200 Lighting control system

Claims (13)

A dimming controller for use with a lighting fixture equipped with two loads having different color temperatures,
A process to determine whether the dimming rate to be achieved is greater than or equal to the threshold,
When the dimming rate is less than or equal to the TH threshold,
A first temporary power calculation process that calculates the first temporary power using the value obtained by adding an offset to the dimming rate and the color ratio of the first load to be realized,
A second temporary power calculation process that calculates the second temporary power using the value obtained by adding the offset to the dimming rate and the color ratio of the second load to be realized,
A first signal transmission process that transmits a signal containing information on the first temporary power and the second temporary power,
The process that executes,
If the dimming rate is greater than the threshold,
A third temporary power calculation process calculates the first temporary power using the value obtained by subtracting the offset from the dimming rate and the color ratio of the first load,
A fourth temporary power calculation process calculates the second temporary power using the value obtained by subtracting the offset from the dimming rate and the color ratio of the second load,
A second signal transmission process transmits a signal containing information of the first temporary power calculated from the third temporary power calculation process and the second temporary power calculated from the fourth temporary power calculation process.
The process that executes,
A dimming controller configured to perform the following actions . A lighting fixture having two loads with different color temperatures,
The signal transmitted from the dimming controller is received and the signal reception processing is performed.
A restoration process to reconstruct the first and second temporary powers from the aforementioned signals and to determine the restored first temporary power and restored second temporary power,
A dimming rate reproduction process that reproduces the dimming rate by removing the offset from the sum of the restored first temporary power and the restored second temporary power,
Based on the restored first temporary power and the restored second temporary power, a first color ratio reproduction process is performed to reproduce the color ratio of the first load,
Based on the restored first temporary power and the restored second temporary power, a second color ratio reproduction process is performed to reproduce the color ratio of the second load,
A first dimming rate calculation process calculates the dimming rate of the first load from the dimming rate reproduced by the dimming rate reproduction process and the color ratio of the first load reproduced by the first color ratio reproduction process.
A second dimming rate calculation process calculates the dimming rate of the second load from the dimming rate reproduced by the dimming rate reproduction process and the color ratio of the second load reproduced by the second color ratio reproduction process,
The driving power of the first load is updated according to the dimming rate of the first load.
A drive power update process that updates the drive power of the second load based on the dimming ratio of the second load,
A lighting fixture configured to perform the following actions. The dimming controller according to claim 1, wherein in the first temporary power calculation process, the first temporary power is calculated by the following formula, and in the second temporary power calculation process, the second temporary power is calculated by the following formula.
First temporary power = Color ratio of the first load / 100 * (dimming rate + offset)
Second temporary power = Color ratio of the second load / 100 * (dimming rate + offset) The lighting fixture according to claim 2, wherein the dimming rate of the first load and the dimming rate of the second load are calculated by the following formula.
Dimming ratio of the first load = (Restored first temporary power + Restored second temporary power - Offset) * Restored first temporary power / (Restored first temporary power + Restored second temporary power)
Dimming ratio of the second load = (Restored first temporary power + Restored second temporary power - Offset) * Restored second temporary power / (Restored first temporary power + Restored second temporary power) The dimming controller according to claim 1 , wherein in the third temporary power calculation process, the first temporary power is calculated by the following formula, and in the fourth temporary power calculation process, the second temporary power is calculated by the following formula.
First temporary power = 100 - Color ratio of the first load / 100 * (200 - Dimming rate - Offset)
Second temporary power = 100 - Color ratio of the second load / 100 * (200 - Dimming rate - Offset) The lighting fixture according to claim 2, further comprising a process to determine whether the sum of the restored first temporary power and the restored second temporary power is greater than or equal to a threshold, and if the sum of the restored first temporary power and the restored second temporary power is greater than the threshold, the dimming rate of the first load and the dimming rate of the second load are calculated by the following formula.
Dimming ratio of the first load = (Restored first temporary power + Restored second temporary power - Offset) * (100 - Restored first temporary power) / ((100 - Restored first temporary power) + (100 - Restored second temporary power))
Dimming ratio of the second load = (Restored first temporary power + Restored second temporary power - Offset) * (100 - Restored second temporary power) / ((100 - Restored first temporary power) + (100 - Restored second temporary power)) The dimming controller according to claim 1 , which calculates the threshold value using the dimming rate and the offset by the following formula.
Threshold = 100% - Offset The lighting fixture according to claim 6 , wherein the threshold is expressed by the following formula.
Threshold = 100% The dimming controller according to claim 1, wherein in the first signal transmission process and the second signal transmission process, a pulse width modulated signal is transmitted, the signal having a period determined from one of the first temporary power and the second temporary power and a duty cycle determined from the other. The lighting fixture according to claim 2, wherein the signal reception process receives a pulse-width modulated signal having a period determined by one of the first temporary power and the second temporary power, and a duty cycle determined by the other. A lighting control system comprising the dimming controller described in claim 1 and the lighting fixture described in claim 2. A lighting control system comprising a conversion unit inside the lighting fixture or between the dimming controller and the lighting fixture,
The aforementioned conversion unit is
The lighting control system according to claim 11 , configured to perform a conversion process that converts a signal transmitted from the dimming controller into a digital signal. The lighting control system according to claim 12 , characterized in that the signal is a pulse-width modulated signal having a period determined by one of the first temporary power and the second temporary power and a duty cycle determined by the other.