KR100779348B1 - Apparatus and method for controlling dimming - Google Patents

Abstract

An apparatus and a method for controlling illumination are provided to reduce the energy by controlling a lamp control system using schedule software. An apparatus and a method for controlling illumination includes a rectifying unit(110), a switching control unit(130), a switching rectifying unit(150), and an accumulating unit(170). The rectifying unit rectifies an input AC signal and outputs the rectified signal. The switching control unit outputs a switching control signal which is controlled by a frequency and a duty rate according to a predetermined illumination. The switching rectifying unit outputs a switching rectifying signal by switching the rectified signal based on the switching control signal. The accumulating unit accumulates the switching rectifying unit and outputs an illumination control signal. The switching control unit varies a frequency of the switching control signal according to signal levels of the rectified signal.

Description

[0001] Apparatus and method for controlling dimming [0002]

The present invention relates to an illumination control apparatus, and more particularly, to an apparatus and method for controlling illumination by switching an input AC voltage with a switching control signal capable of varying a frequency and a duty rate.

In general, the voltage-current of a lamp such as a fluorescent lamp has negative characteristics. Because of this characteristic, if no action is taken, after the lamp is turned on, the voltage of the lamp continuously decreases and the current of the lamp rises, eventually the lamp is destroyed. A ballast is usually required to prevent this phenomenon. In other words, the ballast constantly supplies a constant voltage to the lamp to limit the current and intermittently discharge the lamp, thereby maintaining the lamp lighting continuously.

On the other hand, in accordance with the improvement of the standard of living, in recent years, besides the above-mentioned basic functions, the development of a ballast for a pleasant lighting environment has been made. For example, there has been developed a stabilizer that improves the quality of illumination such as glare removal, illumination control for the atmosphere, and energy saving. Particularly, an electronic ballast for dimming control It is widely being developed.

Currently developed electronic ballasts for dimming control use a phase-controlled input AC signal and a method of controlling dimming by using a DC signal having a predetermined range (for example, 0 to 10).

However, since such an electronic ballast for dimming control requires a line for a DC signal in addition to an input AC signal, there is a problem in that the circuit configuration is complicated, energy efficiency is lowered, and it can not be directly applied to a general ballast without a dimming control function. In addition, when controlling a plurality of lights simultaneously, the electronic ballast for dimming control has a problem that phases of the power lines are changed to cause defects of the ballasts.

An aspect of the present invention is to provide an apparatus for controlling an illuminance by switching an input AC voltage with a switching control signal capable of varying a frequency and a duty rate.

According to another aspect of the present invention, there is provided a method of controlling illuminance by switching an input AC voltage with a switching control signal capable of varying a frequency and a duty rate.

According to an aspect of the present invention, there is provided an illumination control apparatus including a rectifier, a switching controller, a switching rectifier, and an integrating unit. The rectification section rectifies the input AC signal and outputs a rectified signal. The switching control unit outputs a switching control signal whose frequency and duty rate are adjusted according to the setting roughness. The switching rectification part switches the rectified signal according to the switching control signal and outputs a switching rectified signal. The integrating unit integrates the switching rectification signal and outputs an illuminance control signal.

Preferably, the switching control unit varies the frequency of the switching control signal according to the signal level of the rectified signal, and more preferably, increases the frequency of the switching control signal as the signal level of the rectified signal decreases.

The switching controller includes an interface, a frequency determiner, and a signal generator. The interface unit performs an interface with an external input device for setting the setting illuminance to receive the setting illuminance. The frequency determining unit determines the frequency and the duty ratio of the switching control signal in response to the setting illuminance. The signal generator generates the switching control signal in response to the determined frequency and the duty rate.

The frequency determining unit may further generate a display control signal for displaying the setting illuminance and the state of the illuminance control apparatus in response to the setting illuminance, And a display unit for displaying the illuminance and the status.

The switching rectifier includes a main switching unit and a reflux switching unit. The main switching unit transmits the rectified signal to the integrating unit in response to the switching control signal so that energy corresponding to the rectified signal is accumulated in the integrating unit. The reflux switching unit short-circuits the input line of the integrating unit in response to the switching control signal so that the energy accumulated in the integrating unit is discharged.

In this case, the main switching unit and the reflux switching unit are preferably switching semiconductor devices.

According to another aspect of the present invention, there is provided an illumination control system including at least one illumination control module connected to at least one illumination channel, and an illuminance setting module. The illuminance setting module communicates with at least one illuminance control module, and for each of the at least one illuminance control module, sets the illuminance for each illumination channel and outputs the illuminance as a illuminance setting signal. Wherein the illumination control module generates an illumination control signal by switching an input AC voltage using a switching control signal whose frequency and duty rate are adjusted in accordance with a setting illuminance corresponding to the illuminance setting signal for each illumination channel, And outputs a control signal to at least one lighting device connected to the illumination channel.

Meanwhile, the illumination control system according to another embodiment of the present invention may further include a wireless setting module for setting the setting illuminance and outputting the setting illuminance as a wireless setting signal. At this time, the roughness setting module outputs the roughness setting signal in response to the wireless setting signal, and the roughness control module generates the roughness control signal according to the setting roughness corresponding to the wireless setting signal for each illumination channel .

On the other hand, it is preferable that the illuminance setting module automatically sets the setting illuminance in response to a user's input or in response to a season, a time, and a current illuminance.

The illuminance setting module may be a software-installed embedded terminal.

According to another aspect of the present invention, there is provided an illuminance setting method including: setting a setting illuminance; outputting a switching control signal whose frequency and duty rate are adjusted according to the illuminance; , Switching the rectified signal generated by rectifying the input AC signal to output a switching rectified signal, and outputting the roughing control signal by integrating the switching rectified signal.

The step of outputting the switching control signal includes the steps of receiving the setting roughness, determining a frequency and a duty rate of the switching control signal in response to the setting roughness, and outputting the switching control signal in response to the frequency and the duty rate. And generating a control signal.

The determining of the frequency and the duty rate may include determining a frequency of the switching control signal according to a signal level of the rectified signal, and the step of determining the frequency and the duty rate may include determining a signal level of the rectified signal, It is more preferable to increase the frequency of the switching control signal.

Meanwhile, the illuminance setting method according to the embodiment of the present invention includes the steps of generating a display control signal for displaying the setting illuminance and the current illuminance status in response to the setting illuminance, And displaying the illuminance status.

On the other hand, it is preferable that the setting of the setting illuminance automatically sets the setting illuminance in response to a user's input or in response to a season, a time, and a current illuminance.

As described above, the dimming control apparatus according to the embodiment of the present invention is advantageous in that the wiring is simple, the installation cost is reduced, the installation is simple, the maintenance and repair is easy, the energy according to the amount of lighting is saved, and the power factor is large .

Also, the dimming control system according to the embodiment of the present invention is advantageous in that energy can be saved by efficiently controlling a large-scale lighting control system using schedule software or the like.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

1 is a configuration diagram of a roughness control apparatus according to an embodiment of the present invention. FIG. 5 is a flow chart of a method of controlling the illuminance according to the embodiment of the present invention, and FIG. 6 is a flowchart illustrating a method of controlling the illuminance of each stage Fig. 7 is a diagram for explaining a signal waveform in Fig.

The illumination controller 100 may further include a noise eliminator 190 including a rectifier 110, a switching controller 130, a switching rectifier 150, and an integrating unit 170. The rectifier 110 rectifies the input AC signal AC_IN (Fig. 6A) to generate a rectified signal (Fig. 6B), and outputs the generated rectified signal. That is, the rectifying unit 110 converts the input AC signal AC_IN in the form of sinusoidal wave into a pulsating current so that the rectifying signal B can be freely switched by the switching rectifier 135.

The operation of the roughness control device 100 is started by setting a desired setting illuminance (step S501 in FIG. 5). In the embodiment of the present invention, the setting illuminance can be set by various methods. For example, the user can input the setting illuminance directly by using an external input device, and the setting illuminance can be automatically set according to the time, place, season, or surrounding illumination environment. In the case where the setting is automatically made, the software may be installed in the embedded terminal so that the setting illuminance is automatically output.

Meanwhile, an external input device or an embedded terminal communicates with the illuminance control device 100 in an arbitrary manner including wired and wireless, and transmits the setting illuminance. A person skilled in the art can easily configure the configuration for transmitting the setting roughness, and thus a detailed description thereof will be omitted.

Referring back to FIG. 1, the switching controller 130 outputs a switching control signal whose frequency and duty rate are adjusted according to the setting illuminance transmitted (or inputted) from the outside (step S503 of FIG. 5) . In the embodiment of the present invention, the switching controller 130 preferably changes the frequency of the switching control signal according to the signal level of the rectified signal, and increases the frequency of the switching control signal as the signal level of the rectified signal becomes smaller More preferable. Hereinafter, the configuration and operation of the switching controller 130 will be described in detail with reference to FIG.

The switching control unit 130 may include an interface unit 131, a frequency determination unit 133, and a signal generation unit 135, and may further include a display unit 137. The interface unit 131 receives the setting illuminance by performing an interface with an external apparatus that transmits a setting illuminance, such as the above-described external input apparatus or an embedded terminal. Also, as described above, the interface unit 131 can communicate with an external apparatus by an arbitrary communication method.

The frequency determining unit 133 determines the frequency and the duty rate of the switching control signal in response to the setting illuminance. In the embodiment of the present invention, the switching control signal is preferably a rectangular wave signal, and in this case, the rectified signal B is switched in accordance with a switching control signal which is a rectangular wave.

As shown in Fig. 6, the level of the rectified signal B can be changed. The energy of the rectified signal B is transferred to the succeeding integrating unit 170 irrespective of the level of the rectified signal B. [ On the other hand, when switched to a low frequency, the energy of the high level rectified signal can be transferred to the subsequent integrating unit 170, but the energy of the low level rectified signal can not be properly delivered to the subsequent integrating unit 170 May occur.

Therefore, in the embodiment of the present invention, it is necessary to vary the frequency of the switching control signal according to the level of the rectified signal. That is, when the level of the rectified signal to be switched is low, the frequency determination unit 133 of the switching control unit 150 needs to increase the frequency of the switching control signal. At this time, the frequency value corresponding to the level of the rectified signal may be experimentally determined.

The signal generating unit 135 generates a switching control signal in response to the determined frequency and the duty rate. That is, the signal generating section 135 generates a switching control signal having a frequency and a pulse width corresponding to the frequency and the duty rate determined by the frequency determining section 133 in accordance with the setting illuminance.

On the other hand, in the embodiment of the present invention, the frequency determination unit 133 may further generate a display control signal for displaying the setting illuminance and the state of the illuminance control apparatus 100 in response to the setting illuminance (step S509 of FIG. 5) . In this case, the switching controller 130 may further include a display unit 137, and the display unit 137 displays the setting illuminance and the status in response to the display control signal (step S511 of FIG. 5). The user will be able to control the illumination controller 100 efficiently by confirming the setting illuminance and status displayed by the display unit 137. [

The switching rectifier 150 switches the rectified signal (B in FIG. 6) according to the switching control signal to generate the switching rectified signal (C in FIG. 6), and outputs the generated switching rectified signal C to the accumulator 170 (Step S505 of FIG. 5). The switching rectification part 150 may be implemented in various forms such as a method of multiplying the switching control signal C by the rectification signal B and the switching rectification part 150 in the embodiment of the present invention may be realized by a switching rectification part 150, Likewise, it is preferable to be implemented as two switching units 151 and 153 which are switched in response to a switching control signal. Hereinafter, the configuration and operation of the switching rectifier 150 implemented by two switching units will be described with reference to FIG.

The switching rectifying part 150 includes a main switching part 151 and a reflux switching part 153. The main switching unit 151 transmits the rectified signal B to the accumulating unit 170 in response to the switching control signal so that energy corresponding to the rectified signal B is accumulated in the accumulating unit 170. [ The reflux switching unit 153 short-circuits the input line of the integrating unit 170 in response to the switching control signal so that the energy stored in the integrating unit 170 is released.

More specifically, in the embodiment of the present invention, the main switching unit 151 and the reflux switching unit 153 operate in reverse (i.e., alternately). That is, when the main switching unit 151 is turned on, the reflux switching unit 153 is turned off. When the main switching unit 151 is turned off, the reflux switching unit 153 is turned on, C is controlled.

When the main switching unit 151 is turned on and the reflux switching unit 153 is turned off, the rectified signal B is transferred to the integrating unit 170 and accumulated as energy. Since the main switching unit 151 and the reflux switching unit 153 operate in response to the illumination control signal as the switching control signal, if the main switching unit 151 is turned off after a predetermined period of time, 153 are turned on, and in this case, the accumulated energy in the integrating unit 170 is released.

The switching rectification signal shown in C of FIG. 6 is a signal controlled at a 50% duty rate. In this case, the ratio of the period in which the main switching unit 151 is turned on and the reflux switching unit 153 is turned off and the period in which the main switching unit 151 is turned off and the reflux switching unit 153 is turned on is set to 50% , It is possible to have a duty rate of 50%. At this time, the period during which the main switching unit 151 or the reflux switching unit 153 is turned on or off is controlled by the frequency determination unit 133. [

Meanwhile, in the embodiment of the present invention, the main switching unit 151 and the reflux switching unit 153 may be implemented using any switching device, but in the embodiment of the present invention, a switching semiconductor device including a transistor and a diode .

The integrating unit 170 integrates the switching rectification signal (C in Fig. 6) to generate the integration signal (D in Fig. 6) and outputs the integration signal D as the illumination control signal D (S507 in Fig. 5 step). The illumination control signal D is inputted to the illumination device (the ballast in the case of the illumination device requiring the ballast), and the illumination device is turned on.

The integrating unit 170 may be implemented as an arbitrary circuit for integrating an input signal. However, in the embodiment of the present invention, as shown in FIG. 4, the integrating unit 170 may be implemented by an inductor L and a capacitor C, It is preferable that it is an LC integration circuit that averages. The configuration and operation of the integrating unit 170 implemented by the LC integrating circuit will be described below with reference to FIG.

When the main switching unit 151 of the switching rectifying unit 150 is turned on (the reflux switching unit 153 is turned off), the rectified signal C is transmitted to the integrating unit 170. In this case, A current flows and the capacitor C is charged. After the predetermined time has elapsed, the main switching unit 151 is turned off (the reflux switching unit 153 is turned on), the current of the inductor L flows according to the turn-on of the reflux switching unit 153, C is discharged, and the current flows continuously through the inductor L of the LC integration circuit. As a result, the above-described process is repeated according to the switching control signal, so that the switching rectification signal C is integrated and smoothed to generate the integrated signal D.

On the other hand, the input AC signal AC_IN may include noise due to a characteristic of a transmission line through which a signal is transmitted, a natural phenomenon (for example, a lightning stroke), or a surge voltage applied by an external power source. On the other hand, electromagnetic interference (EMI) is generated in all electronic devices, and EMI generated in the illumination control device 100 may adversely affect other electronic devices.

It is necessary that the illuminance control device 100 should not be influenced by the noise or the surge voltage and that the EMI generated in the illuminance control device 100 does not affect other electronic devices. For this, the illumination controller 100 according to the embodiment of the present invention may further include a noise eliminator 190. The noise eliminator 190 eliminates the noise or the surge voltage included in the input AC signal AC_IN and removes the EMI generated by the roughness controller 100, so that it does not affect other electronic devices.

Since noise or surge voltage included in the input AC signal AC_IN and EMI generated in the illumination controller 100 are typically high frequency signals, the noise eliminator 190 in the embodiment of the present invention is a low- .

Although the above description has been made with reference to an apparatus for controlling illuminance for one illuminating apparatus, the illuminance controlling apparatus of the present invention may be applied to a system for controlling the illuminance of one or more illuminating apparatuses. Hereinafter, a system for controlling the illuminance of one or more lighting apparatus will be described with reference to FIG.

7 is a lighting control system according to another embodiment of the present invention. The illumination control system 700 includes at least one illumination control module 730_1, ... connected to at least one illumination channel 751_1 to 751_N, ..., and an illumination setting module 710, 790).

In FIG. 7, at least one lighting device 751_1_1, 751_1_1, ... is installed in the illumination channel (for example, 751_1). In this case, the illumination channel (for example, 751_1) is directly connected to the ballast in the case of a lighting device requiring a ballast, and to the lighting device in the case of a lighting device that does not require a ballast. In FIG. 7, the lighting devices 751_1_1, 751_1_1,... Include all those that can be electrically lit, including fluorescent lamps. On the other hand, in order to easily control the illuminance, it is preferable that the illumination devices 751_1_1, 751_1_1, ... provided in the illumination channel 751_1 are of the same type.

In FIG. 7, one lighting channel is implemented as one line for convenience of explanation. However, in the embodiment of the present invention, a person having a normal knowledge may use one line depending on the type, , It will be appreciated that one illumination channel may be implemented in more than one line.

7, the illuminance setting module 710 is in communication with at least one illuminance control module 730_1, ..., and for each of the at least one illuminance control module (e.g., 730_1) For example, 751_1 to 751_N, and outputs it as an illuminance setting signal.

Meanwhile, in the embodiment of the present invention, the setting illuminance can be set by various methods. In a simple manner, the user can arbitrarily set the setting illuminance. Alternatively, the setting illuminance can be automatically set according to season, time, current illuminance, and the like.

In the case of automatic setting, the setting illuminance can be automatically set by installing the software programmed in the illuminance setting module 710 in a predetermined manner. In this case, the illuminance setting module 710 may be a software-installable embedded terminal.

Meanwhile, the illuminance setting module 710 communicates with at least one illuminance control module 730_1, ..., by any method including wire and wireless, and transmits the illuminance setting signal. In this case, communication may be performed according to any wired or wireless communication standard including ETHENET, RS232, RS485, RS422, and the like.

Referring again to Figure 7, the illumination control module (e.g., 730_1) controls at least one illumination channel (e.g., 751_1 to 751_N) coupled to the illumination control module 730_1.

More specifically, the illumination control module (for example, 730_1) controls the switching of the illumination (for example, 751_1 to 751_N) according to the setting illuminance corresponding to the illuminance setting signal, And generates an illuminance control signal by switching an input AC voltage using a control signal. Thereafter, the illumination control module 730_1 transmits the generated illumination control signals to at least one illumination device 751_1_1, 751_1_2, ..., 751_N_1 (751_1_1 to 751_N1) connected to the illumination channels 751_1 to 751_N for each of the illumination channels 751_1 to 751_N , 751_N_2, ...).

In the embodiment of the present invention, the illumination control module 730_1 may be implemented using the illumination control device 100 shown in Fig. That is, the illumination control module 730_1 can be implemented by providing an illumination control device (see the illumination control device 100 of FIG. 1) for each of the illumination channels 751_1 to 751_N. A person having ordinary skill in the art will be able to implement the illumination control module 730_1, ... using the illumination control device 100 of FIG. 1, so that a description of the specific configuration of the illumination control module 730_1 Is omitted.

On the other hand, the illumination control system 700 may further include a wireless setting module 790 for setting the setting illuminance and outputting the setting illuminance as a wireless setting signal. In order to allow the user to easily set the setting illuminance, the embodiment of the present invention can provide the wireless setting module 790 in the form of a remote control.

Similarly to the method of setting the setting illuminance using the illuminance setting module 710, the user can set the setting illuminance using the wireless setting module 790. [ For example, the wireless setting module 790 transmits the setting illuminance set by the user to the illuminance setting module 710 as a wireless setting signal. The illuminance setting module 710 receives the wireless setting signal and outputs an illuminance setting signal in response to the wireless setting signal. That is, the roughness setting module outputs the roughness setting signal in accordance with the setting roughness corresponding to the wireless setting signal.

Meanwhile, in the embodiment of the present invention, the wireless setting module 790 can independently control at least one illumination control module 730_1, .... For example, the wireless setting module 790 may transmit the setting illuminance set by the user to the illuminance control module (for example, 730_1) as a wireless setting signal. In this case, the illuminance control module illuminance control module 730_1, For each of the illumination channels (for example, 751_1 to 751_N), the illumination control signal is generated in accordance with the setting illuminance corresponding to the wireless setting signal.

Meanwhile, in the embodiment of the present invention, the wireless setting module 790 is preferably implemented as a remote controller using infrared (IR).

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS A brief description of each drawing is provided to more fully understand the drawings recited in the description of the invention.

1 is a configuration diagram of a roughness control apparatus according to an embodiment of the present invention.

Fig. 2 is a configuration diagram of the switching control unit of Fig. 1. Fig.

Fig. 3 is a configuration diagram showing an example of the switching rectifying section of Fig. 1. Fig.

4 is a circuit diagram showing an example of the integrating unit of Fig.

5 is a flowchart of a method of controlling illumination according to an embodiment of the present invention.

6 is a diagram for explaining signal waveforms at each stage of the roughness control apparatus.

7 is a configuration diagram of a roughness control system according to another embodiment of the present invention.

Claims (17)

A rectifying unit for rectifying the input AC signal and outputting a rectified signal; A switching controller for outputting a switching control signal whose frequency and duty rate are adjusted according to the setting illuminance; A switching rectifier for switching the rectified signal according to the switching control signal to output a switching rectified signal; And And an integrating unit for integrating the switching rectification signal and outputting a roughness control signal. The method according to claim 1, Wherein the switching control unit varies the frequency of the switching control signal according to a signal level of the rectified signal. 3. The method of claim 2, Wherein the switching controller increases the frequency of the switching control signal as the signal level of the rectified signal decreases. The apparatus according to claim 1, An interface unit configured to interface with an external input device for setting the setting illuminance and to receive the setting illuminance; A frequency determining unit that determines a frequency and a duty rate of the switching control signal in response to the setting illuminance; And And a signal generator for generating the switching control signal in response to the determined frequency and the duty rate. 5. The method of claim 4, Wherein the frequency determining unit further generates a display control signal for displaying the setting illuminance and the state of the illuminance control apparatus in response to the setting illuminance, Wherein the switching control unit further comprises a display unit for displaying the setting illuminance and the status in response to the display control signal. The apparatus according to claim 1, wherein the switching rectifier includes: A main switching unit for transferring the rectified signal to the integrating unit in response to the switching control signal so that energy corresponding to the rectified signal is accumulated in the integrating unit; And And a reflux switching unit for shorting the input line of the integrating unit in response to the switching control signal so that the energy stored in the integrating unit is released. The method according to claim 6, Wherein the main switching unit and the reflux switching unit are switching semiconductor devices. At least one illumination control module coupled to at least one illumination channel; And And an illuminance setting module for communicating with at least one illuminance control module and for each of the at least one illuminance control module, setting illuminance for each illumination channel and outputting the illuminance as a illuminance setting signal, Wherein the illumination control module generates an illumination control signal by switching an input AC voltage using a switching control signal whose frequency and duty rate are adjusted in accordance with a setting illuminance corresponding to the illuminance setting signal for each illumination channel, And at least one illumination control module outputting a control signal to at least one lighting device connected to the illumination channel. 9. The method of claim 8, Further comprising a wireless setting module for setting the setting illuminance and outputting the setting illuminance as a wireless setting signal, The illuminance setting module outputs the illuminance setting signal in response to the radio setting signal, Wherein the illumination control module generates the illumination control signal according to a setting illuminance corresponding to the wireless setting signal for each illumination channel. 9. The method of claim 8, Wherein the illuminance setting module automatically sets the setting illuminance in response to a user's input or in response to a season, a time, and a current illuminance. 9. The method of claim 8, Wherein the illuminance setting module is a software-installable embedded terminal. Setting a setting illuminance; Outputting a switching control signal whose frequency and duty rate are adjusted according to the setting illuminance; Switching a rectified signal generated by rectifying an input AC signal according to the switching control signal to output a switching rectified signal; And And outputting a roughness control signal by integrating the switching rectification signal. 13. The method of claim 12, wherein outputting the switching control signal comprises: Receiving the setting illuminance; Determining a frequency and a duty rate of the switching control signal in response to the setting illuminance; And And generating the switching control signal in response to the frequency and the duty rate. 14. The method of claim 13, Wherein the step of determining the frequency and the duty rate determines the frequency of the switching control signal according to the signal level of the rectified signal. 15. The method of claim 14, Wherein the step of determining the frequency and the duty rate increases the frequency of the switching control signal as the signal level of the rectified signal decreases. 13. The method of claim 12, Generating a display control signal for displaying the setting illuminance and the current illuminance status in response to the setting illuminance; And Further comprising the step of displaying the setting illuminance and the illuminance status in response to the display control signal. 13. The method of claim 12, Wherein the step of setting the setting illuminance automatically sets the setting illuminance in response to a user's input or in response to a season, a time, and a current illuminance.

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