Patent Publication Number: US-2016234906-A1

Title: Lighting system and method for controlling lighting system

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority of Japanese Patent Application Number 2015-024581 filed on Feb. 10, 2015, the entire content of which is hereby incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a lighting system which controls dimming of a lighting device. 
     2. Description of the Related Art 
     Conventionally, a lighting system has been known which controls a dimming level of a lighting device such as an LED light on the ceiling. 
     For example, according to a dimming control system disclosed in Japanese Unexamined Patent Application Publication No. 2004-349065, a dimming-control parent device transmits, to a dimming-control terminal, a control-target value for adjusting the amount of light emitted from a lighting device. The dimming control parent device stores an operation schedule in which a control-target value and a time to start the control are associated with one another, and transmits the control-target value to the dimming control terminal when the current time comes to the start time. 
     SUMMARY 
     According to the above conventional technique, the amount of light emitted from a lighting device is adjusted in accordance with a preset schedule such that the illuminance of a lighting device at a certain time approximates to a control-target value for that time. 
     For example, from the viewpoint of energy saving, however, the amount of light emitted from the lighting device may be changed or maintained according to not only the current time, but environment items appropriately selected from among various environmental items. 
     In a lighting system which provides a comparatively large area with illumination light using a plurality of lighting devices, environment light may have different influences on subregions, for example. In this case, a problem arises as to how dimming of the plurality of lighting devices needs to be controlled. 
     In view of the above conventional problem, the present disclosure describes, in one general aspect, a lighting system which can appropriately dim a plurality of lighting devices and a method for controlling the lighting system, according to the environment where the plurality of lighting devices are installed. 
     A lighting system according to an aspect of the present disclosure is a lighting system including: a plurality of lighting devices each including a light source and a lighting circuit which causes the light source to provide illumination; a plurality of lighting controllers each of which controls dimming of one or more lighting devices among the plurality of lighting devices by controlling the lighting circuit included in each of the one or more lighting devices; and a system controller which controls the plurality of lighting controllers. The system controller includes: a timer which outputs a counter value indicating a time; a schedule storage for storing schedule information which includes an instruction directed to the plurality of lighting controllers and a time associated with the instruction; a first communication circuit which transmits information to the plurality of lighting controllers; and an instruction controller which identifies, from the schedule information, an instruction associated with the time indicated by the counter value, and causes the first communication circuit to transmit control information which includes the identified instruction and an address assigned to at least one lighting controller among the plurality of lighting controllers. Each of the plurality of lighting controllers includes: a sensor which detects (i) a person in a space where the one or more lighting devices, the dimming of which is controlled by the each of the plurality of lighting controllers, are disposed, and (ii) brightness of the space; a second communication circuit which receives the control information transmitted from the system controller; an address storage which stores an own address of the each of the plurality of lighting controllers that is an address assigned to the each of the plurality of lighting controllers; and a dimming controller which switches to one of modes that is indicated in the control information from another of the modes and executes the one of the modes, if the address indicated in the control information received by the second communication circuit matches the own address, the modes including (a) a human detection mode for controlling the dimming in accordance with a result of human detection by the sensor, (b) a brightness detection mode for controlling the dimming in accordance with a result of detection of the brightness by the sensor, and (c) a dimming level fixed mode for controlling the dimming by maintaining a dimming level at a fixed value. 
     A method for controlling a lighting system according to an aspect of the present disclosure is a method for controlling a lighting system which includes: a plurality of lighting controllers each of which controls dimming of one or more lighting devices; and a system controller which controls the plurality of lighting controllers. The system controller includes: a timer which outputs a counter value indicating a time; and a schedule storage for storing schedule information which includes an instruction directed to the plurality of lighting controllers and a time associated with the instruction. Each of the plurality of lighting controllers includes: an address storage which stores an own address of the each of the plurality of lighting controllers that is an address assigned to the each of the plurality of lighting controllers; and a sensor which detects a person in a space where the one or more lighting devices are disposed, and brightness of the space. The method includes: identifying, by the system controller from the schedule information, an instruction associated with the time indicated by the counter value; transmitting, to the plurality of lighting controllers by the system controller, control information which includes the identified instruction and an address assigned to at least one lighting controller among the plurality of lighting controllers; receiving, by each of the plurality of lighting controllers, the control information transmitted from the system controller; and switching, by each of the plurality of lighting controllers, to one of modes that is indicated in the control information from another of the modes, and executing, by the lighting controller, the one of the modes, if the address indicated in the control information matches the own address, the modes including (a) a human detection mode for controlling the dimming in accordance with a result of human detection by the sensor, (b) a brightness detection mode for controlling the dimming in accordance with a result of detection of the brightness by the sensor, and (c) a dimming level fixed mode for controlling the dimming by maintaining a dimming level at a fixed value. 
     The lighting system according to an aspect of the present disclosure can appropriately dim a plurality of lighting devices according to the environment where the plurality of lighting devices are installed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The figures depict one or more implementations in accordance with the present teaching, by way of examples only, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1A  illustrates a schematic configuration of a lighting system according to an embodiment; 
         FIG. 1B  illustrates a schematic configuration of a subsystem according to the embodiment; 
         FIG. 2  is a block diagram illustrating a functional configuration of the lighting system according to the embodiment; 
         FIG. 3  is a sequence diagram illustrating a flow of basic operation of the lighting system according to the embodiment; 
         FIG. 4  illustrates an example of schedule information according to the embodiment; 
         FIG. 5  is a first diagram illustrating an example of a flow of operation of a lighting control device according to the embodiment; 
         FIG. 6  is a second diagram illustrating an example of a flow of operation of the lighting control device according to the embodiment; 
         FIG. 7  illustrates an example of schedule information and an example of parameter information according to Variation 1 of the embodiment; 
         FIG. 8  illustrates an example of schedule information and an example of time-of-day information according to Variation 2 of the embodiment; 
         FIG. 9  illustrates a system control device and a communication terminal according to Variation 3 of the embodiment; 
         FIG. 10  illustrates an example of a lighting system setting screen displayed by the communication terminal according to Variation 3 of the embodiment; 
         FIG. 11  illustrates a system control device and a communication terminal according to Variation 4 of the embodiment; 
         FIG. 12  illustrates an example of a schedule confirmation screen displayed by the communication terminal according to Variation 4 of the embodiment; 
         FIG. 13  illustrates a lighting control device and a communication terminal according to Variation 5 of the embodiment; 
         FIG. 14  illustrates an example of a mode confirmation screen displayed by the communication terminal according to Variation 5 of the embodiment; and 
         FIG. 15  illustrates a flow of instruction information in a subsystem according to Variation 5 of the embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The following describes a lighting system according to an embodiment and variations with reference to the drawings. Note that the embodiment and variations described below each show a specific example of the present disclosure. The numerical values, shapes, materials, constituent elements, the arrangement and connection of the constituent elements, and others indicated in the following embodiment and variations thereof are mere examples, and therefore do not intend to limit the inventive concept. Therefore, among the constituent elements in the following embodiment and variations thereof, constituent elements not recited in any of the independent claims defining the most generic part of the inventive concept are described as arbitrary constituent elements. 
     Note that the drawings are schematic diagrams, and do not necessarily provide strictly accurate illustration. In the drawings, the same numeral is given to the substantially same configuration, and a redundant description thereof may be omitted or simplified. 
     Embodiment 
     The following describes a lighting system according to an embodiment. 
     [Configuration of Lighting System] 
     The first describes a configuration of a lighting system according to an embodiment with reference to  FIGS. 1A, 1B, and 2 . 
       FIG. 1A  illustrates a schematic configuration of lighting system  100  according to the embodiment, and  FIG. 1B  illustrates a schematic configuration of subsystem  101   a  according to the embodiment. 
     Specifically,  FIG. 1A  is a top view illustrating an example of the layout of constituent elements of lighting system  100 , and  FIG. 1B  is a side view of subsystem  101   a  which is a part of lighting system  100 . Note that depictions of the lines that connect lighting control device  120  and lighting devices  150  are omitted from  FIG. 1B . 
     While lighting system  100  is installed in a space (room) which needs lighting such as, for example, a room in an office building, depiction of objects which may be present in the space, such as fixtures and persons, are omitted from  FIGS. 1A and 1B . 
       FIG. 2  is a block diagram illustrating a functional configuration of lighting system  100  according to the embodiment. 
     As illustrated in these drawings, lighting system  100  according to the embodiment includes plural lighting devices  150 , plural lighting control devices  120 , and system control device  110 . 
     Specifically, in the present embodiment, lighting system  100  includes four subsystems ( 101   a  to  101   d ) each of which includes one lighting control device  120  and four lighting devices  150 . 
     Here, although  FIG. 1A  illustrates lighting system  100  which includes four lighting control devices  120  labeled with A to D, (hereinafter, each may also be referred to as “lighting control device A (B, C, or D)”), at least two lighting control devices  120  may be included in lighting system  100 . In other words, lighting system  100  may include two or more subsystems each including one lighting control device  120  and one or more lighting devices  150 . Note that in  FIG. 1A , “01” and “02” in the parentheses shown aside A to D are examples of addresses assigned to lighting control devices  120 . 
     Furthermore, subsystems  101   b  to  101   d  each have the same configuration as that of subsystem  101   a , and thus a detailed description of subsystems  101   b  to  101   d  is omitted in the following. 
     Lighting device  150  includes light source  155  and lighting circuit  152  which causes light source  155  to provide illumination. 
     Lighting device  150  is a ceiling light which includes, for example, a light-emitting device serving as light source  155 , which has one or more light emitting diodes (LEDs). In this case, lighting circuit  152  is a drive circuit (light circuit) which controls operation of the light-emitting device, such as turning on and off and dimming the light-emitting device, for example. 
     System control device  110  controls plural lighting control devices  120 . System control device  110  includes timer  111  which outputs a counter value indicating a time, schedule storage  112  for storing schedule information  200 , first communicator  115  which transmits information to plural lighting control devices  120 , and instruction controller  114 . 
     Schedule information  200  includes an instruction directed to plural lighting control devices  120  and a time associated with the instructions. An example of schedule information  200  will be described below with reference to  FIG. 4 . 
     Instruction controller  114  identifies, from schedule information  200 , an instruction associated with the time indicated by a counter value output from timer  111 . Instruction controller  114  further causes first communicator  115  to transmit control information  119  which includes the identified instruction and an address assigned to at least one of plural lighting control devices  120 . Subsequently, plural lighting control devices  120  receive control information  119 , and at least one lighting control device  120  having the assigned address performs operation in accordance with control information  119 . 
     Note that in the present embodiment, system control device  110  is disposed on the wall of a room, as illustrated in  FIG. 1B . In this case, system control device  110  may include, for example, a switch for tuning on and off the power for the whole of lighting system  100 , a button for generating or updating schedule information  200 , and a display panel for showing the state of lighting system  100 . 
     In the present embodiment, for example, system control device  110  which is a device called an operation panel is disposed, and schedule information  200  is generated or updated through user operation on the above button, for instance. Note that schedule information  200  may be generated or updated using information from a communication terminal such as a smartphone. A description of this aspect is later given as Variation 3. 
     The place where system control device  110  is disposed is not particularly limited, and system control device  110  may be disposed at a place where people cannot see, such as the roof-space, for example. In this case, for example, system control device  110  can receive various instructions from a user through wireless or cable communication between first communicator  115  and a remote control or a mobile terminal, for instance. 
     Lighting control device  120  controls dimming of one or more lighting devices  150  by controlling lighting circuit  152  included in each of one or more lighting devices  150 . For example, lighting control device  120  gives an instruction about a dimming level to lighting circuit  152 , thus performing control (dimming control) for causing lighting device  150  to provide illumination at the dimming level. 
     Note that a dimming level is a type of a variable for adjusting the brightness of a light, and the brightness of the light increases with an increase in the numerical value of the variable (the maximum value is 100%). Furthermore, the dimming level can also be represented as a “dimming degree” or a “dimming ratio”, for example. 
     For example, if lighting control device  120  gives an instruction indicating a dimming level of “100%” to lighting device  150 , lighting control device  120  transmits instruction information corresponding to a dimming level of “100%” to lighting device  150 . In accordance with the instruction information, lighting circuit  152  of lighting device  150  controls light source  155  to set the optical output of light source  155  to the maximum output. 
     Note that lighting circuit  152  controls the optical output of light source  155  according to a pulse width modulation (PWM) signal, for example. However, a technique used for this control is not particularly limited, and dimming of lighting device  150  may be controlled according to a digital signal. 
     For example, if light source  155  includes a plurality of light emitters such as a plurality of electric bulbs, dimming of light source  155  may be controlled by changing the number of light emitters to be turned on, among the light emitters. 
     According to the present embodiment, lighting control device  120  is connected with four lighting devices  150  via signal lines (see  FIG. 1A ), and lighting control device  120  transmits a signal (instruction information) indicating a dimming level through the signal lines, thus causing four lighting devices  150  to provide illumination at the dimming level. 
     More specifically, lighting control device  120  includes sensor device  121 , address storage  122  which stores an own address of the lighting control device that is an address assigned to lighting control device  120 , second communicator  125  which receives control information  119 , and dimming controller  124 . 
     Sensor device  121  detects a person in a space where one or more lighting devices  150  are disposed dimming of which is controlled, and brightness of the space. Sensor device  121  includes an imaging device in the present embodiment, and detects a person and brightness from image data obtained through imaging by the imaging device. 
     For example, sensor device  121  images a target indoor space using a solid state image sensor such as a complementary metal-oxide semiconductor (CMOS) image sensor, and detects a person and brightness from image data obtained as a result of the imaging. 
     Note that the configuration of sensor device  121  is not particularly limited, and sensor device  121  may include two physically separate sensors, namely a human sensing sensor which detects a person and an illuminance sensor which detects brightness, for example. 
     Dimming controller  124  has features of controlling dimming in various modes including a mode in which a result of detection by sensor device  121  is used, and switching between these modes according to an instruction from system control device  110 . 
     Specifically, if the address indicated in control information  119  received by second communicator  125  matches the own address stored in address storage  122 , dimming controller  124  performs the following operation. Dimming controller  124  switches to one of modes, which is indicated in control information  119  received by second communicator  125 , from another of the modes and executes the one of the modes, the modes including (a) a human detection mode for controlling dimming in accordance with a result of human detection by sensor device  121 , (b) a brightness detection mode for controlling dimming in accordance with a result of brightness detection by sensor device  121 , and (c) a dimming level fixed mode for controlling dimming by maintaining a dimming level at a fixed value. 
     Note that if the address indicated in control information  119  does not match the own address, dimming controller  124  ignores the instruction included in control information  119 . 
     In the present embodiment, as illustrated in  FIG. 1A , address “01” is assigned to lighting control devices A and B, and address “02” is assigned to lighting control devices C and D. In this case, as illustrated in  FIG. 2 , when address “01” is included in control information  119 , lighting control devices A and B operate in accordance with the instruction indicated in control information  119 , such as the “human detection mode”, whereas lighting control devices C and D ignore the instruction included in control information  119 . 
     Note that lighting control devices  120  (A and B) to which address “01” is assigned are examples of a first lighting control device, and lighting control devices  120  (C and D) to which address “02” is assigned are examples of a second lighting control device. 
     Accordingly, dimming controller  124  has a function of switching between modes according to times, such as a mode focusing on the presence of a person, a mode focusing on the detected brightness, and a mode intended to maintain a predetermined dimming level, when controlling dimming to change the brightness of one or more lighting devices  150 . 
     Here, illumination region  500  indicated by the dotted rectangle in  FIG. 1A  is an area to which illumination light is supplied from 16 lighting devices  150  included in lighting system  100 . In the present embodiment, illumination region  500  can be defined as an internal area of a room where four subsystems ( 101   a  to  101   d ) are disposed on the ceiling. 
     Illumination region  500  is divided into subregions ( 501   a  to  501   d ) corresponding to four subsystems ( 101   a  to  101   d ). For example, subregion  501   a  is treated as a space where one or more lighting devices  150  (four lighting devices  150  in the present embodiment) are disposed, dimming of which is controlled by lighting control device A included in subsystem  101   a.    
     For example, natural light coming in from a window in the wall of the room falls on illumination region  500 , and thus the brightness of illumination region  500  also depends on, for example, the weather, in addition to the dimming level of each of plural lighting devices  150 . 
     In the present embodiment, subregions  501   a  and  501   b  in the upper portion of  FIG. 1A  are on the window side, whereas subregions  501   c  and  501   d  in the lower portion of the drawing are on the corridor side. Accordingly, the brightness of subregions  501   a  and  501   b  is likely to be influenced by natural light such as sunlight. 
     Note that the layout of lighting system  100  illustrated in  FIG. 1A  and the layout of subsystem  101   a  illustrated in  FIG. 1B  are examples, and different layouts may be used. For example, sensor device  121  may be disposed in one of lighting devices  150  in subsystem  101   a . In this case, lighting control device  120  except sensor device  121 , namely, the body part of lighting control device  120 , may be disposed in the ceiling space or on the wall of a room, for example. In other words, sensor device  121  and the body part of lighting control device  120  may be physically separate. 
     Furthermore, system control device  110  and one of lighting control devices  120  may be achieved as a single device. For example, system control device  110  and one of lighting control devices  120  may be accommodated in an operation panel disposed on the wall. For example, system control device  110  and one of lighting control devices  120  may be accommodated in the body of one of lighting devices  150 . 
     Furthermore, various functions of system control device  110  and lighting control device  120  according to the present embodiment may be achieved by software, such as a program executed on a computer which includes, for instance, a central processing unit (CPU), random access memory (RAM), read only memory (ROM), a communication interface, an I/O port, and a hard disk, or may be achieved by hardware such as an electronic circuit. In the present disclosure, these may be collectively referred to as controller or a control circuit. 
     [Example of Operation of Lighting System] 
     A description of operation of lighting system  100  having the above configuration is given with reference to  FIGS. 3 to 6 . 
     The first describes the flow of basic operation of lighting system  100  with reference to  FIGS. 3 and 4 . 
       FIG. 3  is a sequence diagram illustrating the flow of basic operation of lighting system  100  according to the embodiment. Note that lighting control devices A to D (see  FIG. 1A ) each perform the basic operation of lighting control devices  120  illustrated in  FIG. 3 . 
       FIG. 4  illustrates an example of schedule information  200  according to the embodiment. 
     System control device  110  identifies, from schedule information  200 , an instruction associated with a time indicated by a counter value output from timer  111  (S 10 ). 
     For example, instruction controller  114  obtains counter values output from timer  111  at predetermined intervals, and compares a time indicated by an obtained counter value with times to switch between modes (5:00, 10:00, 17:00, and 22:00 in the case of  FIG. 4 ) indicated in schedule information  200  read from schedule storage  112 . 
     Note that in the present embodiment, schedule information  200  read by instruction controller  114  includes first schedule information  201  and second schedule information  202 . First schedule information  201  is associated with address “01”, and second schedule information  202  is associated with address “02.” In other words, in the present embodiment, first schedule information  201  includes an instruction directed to lighting control devices A and B, and a time associated with the instruction. Second schedule information  202  includes an instruction directed to lighting control devices C and D, and a time associated with the instruction. 
     If the result of the above comparison shows that a time indicated by the obtained counter value matches one of the times to switch between modes, or the obtained counter value indicates a time later than one of the times to switch between modes for the first time within a day (from 0:00 until next 0:00), instruction controller  114  identifies an instruction associated with the time to switch between modes from schedule information  200 . 
     For example, if the counter value obtained by instruction controller  114  indicates “5:00”, instruction controller  114  identifies, from both of first schedule information  201  and second schedule information  202 , “human detection mode” (see  FIG. 4 ) as the instruction to be given to plural lighting control devices  120 . 
     As illustrated in  FIG. 4 , in the present embodiment, first schedule information  201  and second schedule information  202  include dimming levels in the human detection mode for when a person is detected and for when no person is detected. Instruction controller  114  identifies parameters indicating “70%” and “5%” which are dimming levels for address “01” and “100%” and “20%” which are dimming levels for address “02.” 
     System control device  110  further transmits control information  119  which includes the identified instruction to plural lighting control devices  120  (S 11 ). 
     Specifically, instruction controller  114  causes first communicator  115  to transmit control information  119  which includes address “01” and the instruction (“human detection mode”, “70%”, and “5%”) identified as described above. Furthermore, instruction controller  114  causes first communicator  115  to transmit control information  119  which includes address “02” and the instruction (“human detection mode”, “100%”, and “20%”) identified as described above. 
     Lighting control device  120  receives control information  119  transmitted from system control device  110  (S 20 ). 
     Specifically, second communicator  125  receives control information  119 , and delivers received control information  119  to dimming controller  124 . 
     Lighting control device  120  determines whether the address indicated in control information  119  matches the own address stored in address storage  122  (S 21 ). If the result of this determination shows that the address indicated in control information  119  matches the own address (YES in S 21 ), lighting control device  120  switches to one of modes which is indicated in control information  119  from another of the modes and executes the one of the modes, the modes including the human detection mode, the brightness detection mode, and the dimming level fixed mode (S 22 ). 
     If the address indicated in control information  119  does not match the own address (NO in S 21 ), lighting control device  120  does not switch between modes, and continuously executes the mode being executed at the time. 
     As described above, system control device  110  transmits control information  119  to plural lighting control devices  120  each having an address, at a timing in accordance with schedule information  200 . Control information  119  includes the address(es) of one or more lighting control devices  120  which are to operate in accordance with the instruction indicated in control information  119 . 
     In this manner, each of plural lighting control devices  120  can switch between dimming control modes at a timing in accordance with schedule information  200 . 
     The following describes an example of operation of lighting control device  120 , with reference to  FIGS. 5 and 6 . 
       FIG. 5  is a first drawing illustrating an example of a flow of operation of lighting control device  120  according to the embodiment, and  FIG. 6  is a second drawing illustrating an example of a flow of operation of lighting control device  120  according to the embodiment. 
     Specifically,  FIG. 5  illustrates a processing procedure when lighting control device  120  executes the human detection mode, and  FIG. 6  illustrates a processing procedure when lighting control device  120  executes the brightness detection mode. Furthermore, operations illustrated in  FIGS. 5 and 6  can be executed by each of four lighting control devices  120  (A to D) according to the present embodiment independently from other lighting control devices  120 . 
     The following description of  FIG. 5  focuses on an example of operation performed when lighting control devices  120  (A and B) to which address “01” is assigned receive control information  119  which includes address “01” and an instruction (“human detection mode”, “70%”, and “5%”). 
     If received control information  119  which includes the own address indicates the human detection mode, lighting control device  120  changes the dimming level of one or more lighting devices  150  (four lighting devices  150  in the present embodiment), according to a result of human detection by sensor device  121 . 
     Specifically, as illustrated in  FIG. 5 , if a result of detection by sensor device  121  indicates that a person is detected (YES in S 110 ), dimming controller  124  of lighting control device  120  transmits, to four lighting devices  150 , a signal (instruction information) for causing the lighting devices to provide illumination at a dimming level of “70%” (S 111 ). 
     Consequently, four lighting devices  150  each cause light source  155  to provide illumination at a dimming level of “70%.” 
     Further, if a result of detection by sensor device  121  does not indicate that a person is detected (NO in S 110 ), or in other words, the result indicates that no person is detected, dimming controller  124  transmits, to four lighting devices  150 , a signal (instruction information) for causing the lighting devices to provide illumination at a dimming level of “5%” (S 112 ). 
     Consequently, four lighting devices  150  each cause light source  155  to provide illumination at a dimming level of “5%.” 
     Note that the above operation differs from operation performed when lighting control devices  120  (C and D) to which address “02” is assigned receive control information  119  which includes address “02” and an instruction (“human detection mode”, “100%”, and “20%”), in the following respect. Specifically, if a result of detection by sensor device  121  indicates that a person is detected (YES in S 110 ), dimming controllers  124  of lighting control devices  120  each transmit, to four lighting devices  150 , a signal (instruction information) for causing the lighting devices to provide illumination at a dimming level of “100%” (S 111 ). In contrast, if a result of detection by sensor device  121  does not indicate that a person is detected (NO in S 110 ), dimming controllers  124  each transmit, to four lighting devices  150 , a signal (instruction information) for causing the lighting devices to provide illumination at a dimming level of “20%” (S 112 ). 
     As described above, lighting control devices  120  according to the present embodiment each perform control for changing the dimming level of one or more lighting devices  150  to two levels in the human detection mode, according to whether a person is detected or not detected. If lighting control device  120  does not make a switch to another mode (NO in S 113 ), lighting control device  120  controls dimming in the human detection mode continuously. After that, if control information  119  received by second communicator  125  of lighting control device  120  indicates another mode, lighting control device  120  switches the operation to the other mode (YES in S 113 ). 
     For example, when the time becomes 10:00 a.m., system control device  110  identifies “brightness detection mode” (see  FIG. 4 ) from first schedule information  201  associated with address “01” and included in schedule information  200 . 
     System control device  110  transmits control information  119  indicating address “01” and an instruction indicating the “brightness detection mode” to lighting control devices  120 . Control information  119  also includes, as a parameter which is a part of the instruction, information indicating “500 lx” that is a target value of brightness, for example (see S 10  and S 11  in  FIG. 3 , and  FIG. 4 ). 
     As a result, lighting control devices  120  (A and B) each having address “01” as the own address switch the dimming control mode from the human detection mode to the brightness detection mode. 
     In this case, lighting control devices  120  each change the dimming level of one or more lighting devices  150 , according to the result of brightness detection by sensor device  121 . 
     Specifically, as illustrated in  FIG. 6 , if the brightness shown by the detection result of sensor device  121  (illuminance in the present embodiment) does not match the target value “500 lx” (NO in S 120 ), the dimming level is changed according to a magnitude relation between the brightness shown by the detection result and the target value “500 lx.” 
     In other words, if the brightness shown by the detection result is lower than the target value “500 lx” (YES in S 121 ), dimming controller  124  controls four lighting devices  150  to increase the dimming level (S 122 ). For example, if the dimming level indicated in the most previous instruction given to four lighting devices  150  is 70%, dimming controller  124  transmits a signal (instruction information) to four lighting devices  150  in order to cause the lighting devices to provide illumination at a dimming level higher than 70% (for example, 75%). 
     If the brightness shown by the detection result is higher than the target value “500 lx” (NO in S 121 ), dimming controller  124  controls four lighting devices  150  to lower the dimming level of the lighting devices (S 123 ). For example, if the dimming level indicated in the most previous instruction given to four lighting devices  150  is 70%, dimming controller  124  transmits a signal (instruction information) to four lighting devices  150  to cause the lighting devices to provide illumination at a dimming level lower than 70% (for example, 65%). 
     Note that lighting control devices  120  (C and D) to which address “02” is assigned receive control information  119 , but ignore the instruction such as the “brightness detection mode”, which is included in control information  119 , since address “02” is not included in control information  119 . Thus, even after 10:00 a.m., lighting control devices  120  (C and D) continuously execute the “human detection mode.” 
     As described above, lighting control devices  120  according to the present embodiment each detect brightness of a space where one or more lighting devices  150  under control are disposed, and perform control for changing the dimming level of one or more lighting devices  150  in the brightness detection mode to make the detected brightness approximate to the target value. If lighting control device  120  does not make a switch to another mode (NO in S 125 ), lighting control device  120  controls dimming in the brightness detection mode continuously. 
     After that, if control information  119  received by second communicator  125  of lighting control device  120  indicates another mode, lighting control device  120  switches the operation to the other mode (YES in S 125 ). 
     For example, when the time becomes 5:00 p.m. (17:00), system control device  110  transmits, to plural lighting control devices  120 , control information  119  which includes address “01” and an instruction (“human detection mode”, “100%”, and “20%”) (see S 10  and S 11  in  FIG. 3  and  FIG. 4 ). 
     As a result, lighting control devices  120  (A and B) each having address “01” as the own address switch the dimming control mode from the brightness detection mode to the human detection mode. In this case, lighting control devices  120  each change the dimming level of four lighting devices  150  according to the result of human detection by sensor device  121 . Specifically, when a person is detected, the dimming level of each lighting device  150  is controlled so as to be “100%”, whereas when no person is detected, the dimming level of each lighting device  150  is controlled so as to be “20%.” 
     After that, when the time becomes 10:00 p.m. (22:00), for example, system control device  110  transmits, to plural lighting control devices  120 , control information  119  indicating address “01” and the “dimming level fixed mode.” Furthermore, system control device  110  transmits, to plural lighting control devices  120 , control information  119  indicating address “01” and an instruction which indicates the “dimming level fixed mode.” Control information  119  includes, as a parameter which is a part of the instruction, information indicating a dimming level of “0%”, for example (see S 10  and S 11  in  FIG. 3  and  FIG. 4 ). 
     Note that as described above, if a common instruction is to be given to plural lighting control devices  120  having addresses, system control device  110  may transmit, to plural lighting control devices  120 , control information  119  which includes the addresses as the destination addresses. 
     Plural lighting control devices  120  (A to D) operate in accordance with an instruction indicated in control information  119 , since received control information  119  includes “01” and “02” which are the own addresses. Specifically, dimming controllers  124  of lighting control devices  120  each transmit, to four lighting devices  150 , a signal (instruction information) for causing the lighting devices to provide illumination at a dimming level of “0%.” In other words, lighting control devices  120  each transmit instruction information to four lighting devices  150  to turn off the lighting devices, and four lighting devices  150  each turn off light source  155 , according to the instruction information. 
     Note that in the operation illustrated in  FIG. 6 , dimming controller  124  does not need to determine whether the brightness shown by the result of detection by sensor device  121  is exactly the same as the target value. For example, if the brightness shown by the detection result is in a range plus and minus several percent (for example, 5%) from the target value, dimming controller  124  may determine that the brightness shown by the detection result matches the target value (YES in S 120 ). 
     In such a case, dimming controller  124  may determine in a similar manner whether (a value indicating) the brightness shown by the detection result is lower than the target value (S 121 ). In other words, if the brightness shown by the detection result is lower than, for example, a value that is 95% of the target value, dimming controller  124  may determine that (the value indicating) the brightness is lower than the target value (YES in S 121 ). 
     Feedback control (S 120 , S 121 , S 122 , S 123 ) for thus making the brightness shown by the detection result fall within a predetermined range which includes a target value is an example of dimming control for making the brightness indicated by the detection result approximate to the target value. 
     As described above, lighting system  100  according to the present embodiment includes plural lighting devices  150 , plural lighting control devices  120  each of which controls dimming of one or more lighting devices  150 , and system control device  110  which controls plural lighting control devices  120 . 
     System control device  110  identifies an instruction to be given to at least one lighting control device  120  from the time indicated by the counter value of timer  111  and schedule information  200 . System control device  110  further transmits, to plural lighting control devices  120 , control information  119  which includes the address of at least one lighting control device  120  and the identified instruction. 
     Lighting control devices  120  each include sensor device  121  which detects a person in a space where one or more lighting devices  150  are disposed dimming of which is controlled, and brightness of the space, second communicator  125  which receives control information  119 , dimming controller  124 , and address storage  122  which stores an own address. 
     If the address indicated in control information  119  received by second communicator  125  matches the own address, dimming controller  124  switches between dimming control modes in accordance with the instruction indicated in control information  119 . Specifically, dimming controller  124  switches to one of modes, which is indicated in control information  119 , from another of the modes and executes the one of the modes, the modes including the human detection mode, the brightness detection mode, and the dimming level fixed mode. 
     In this manner, system control device  110  can control plural lighting control devices  120  independently from one another such that dimming is controlled in different modes for times of day, for example. 
     During the morning, lighting control devices  120  each control dimming of one or more lighting devices  150  in the human detection mode which focuses on whether a person is present, for example. Thus, if a person is present in a target space (one of subregions  501   a  to  501   d ), lighting control devices  120  can brightly illuminate an area where the person moves by making the dimming level of one or more lighting devices  150  comparatively high. Furthermore, if a person is not present, minimum brightness, which is determined taking into consideration a possibility of a person coming into the space, for example, can be secured by making the dimming level of one or more lighting devices  150  comparatively low, while keeping power consumption low. 
     For example, two lighting control devices  120  (A and B) on the window side control dimming of one or more lighting devices  150 , during the daytime, in the brightness detection mode which is an operation mode focusing on the brightness. In other words, the dimming level of one or more lighting devices  150  is adjusted to maintain, for example, appropriate brightness for human activity, taking into consideration the environment light at the place where one or more lighting devices  150  under control are installed. 
     In this manner, for example, in a state where sunlight coming in from a window maintains sufficient brightness, the dimming level of plural lighting devices  150  for a space on the window side (subregions  501   a  and  501   b ) is made comparatively low even if a person is present in the space. As a result, power consumption of lighting system  100  can be kept low. 
     Furthermore, during the daytime, two lighting control devices  120  (C and D) on the corridor side control dimming of one or more lighting devices  150  in the human detection mode continuously from the morning. In this manner, for example, in a space (subregions  501   c  and  501   d ) which is comparatively far from the window and thus is assumed to be difficult to maintain sufficient brightness with sunlight, lighting control devices  120  control dimming of plural lighting devices  150  according to whether a person is present. In other words, this achieves effective dimming control of plural lighting devices  150  and reduction in power consumption. 
     During the night, lighting control devices  120  each control dimming of lighting devices  150  in the dimming level fixed mode intended to maintain a predetermined dimming level. For example, assuming that no person is present, lighting control devices  120  operate to maintain the dimming level of lighting devices  150  at “0%.” 
     In this manner, lighting system  100  according to the present embodiment changes or maintains the dimming level of one or more lighting devices  150  according to an environmental item appropriately selected for each of time-series sections from among various environmental items (such as whether a person is present, brightness, and use condition of a target space). 
     Specifically, the dimming control mode of each of plural lighting control devices  120  can be switched to another mode in accordance with a preset schedule. 
     Accordingly, lighting system  100  can appropriately dim plural lighting devices  150  included in lighting system  100  according to the environment where lighting devices  150  are installed. 
     In the present embodiment, schedule information  200  includes first schedule information  201  and second schedule information  202 . First schedule information  201  includes an instruction directed to at least one lighting control device  120  (first lighting control device), and a time associated with the instruction. Second schedule information  202  includes an instruction directed to at least one lighting control device  120  (second lighting control device) to which a different address from the address of the first lighting control device is assigned, and a time associated with the instruction. 
     If instruction controller  114  identifies, from first schedule information  201 , an instruction associated with the time indicated by the counter value of timer  111 , instruction controller  114  causes first communicator  115  to transmit control information  119  which includes the identified instruction and the address assigned to the first lighting control device. 
     Furthermore, if instruction controller  114  identifies, from second schedule information  202 , an instruction associated with the time indicated by the counter value of timer  111 , instruction controller  114  causes first communicator  115  to transmit control information  119  which includes the identified instruction and the address assigned to the second lighting control device. 
     In other words, schedule information  200  according to the present embodiment includes information which indicates associations of times and instructions directed to different addresses. This allows timings of switching between modes to be readily edited or updated for each of plural lighting control devices  120  each associated with one of the addresses, for example. 
     Furthermore, in the present embodiment, instruction controller  114  causes first communicator  115  to transmit, if the identified instruction indicates the human detection mode, control information  119  which includes parameters indicating dimming levels for the human detection mode for when a person is detected and for when no person is detected. If the address indicated in control information  119  matches the own address and control information  119  indicates the human detection mode, dimming controller  124  controls dimming, using a dimming level indicated by a parameter according to the result of human detection by sensor device  121 . 
     In this manner, even if dimming controller  124  controls dimming in the “human detection mode” during both the morning and night, dimming controller  124  can adjust the dimming level for when a person is detected during the nighttime to, for example, a value greater than the dimming level for when a person is detected during the morning. 
     In other words, in the human detection mode which focuses on whether a person is present, dimming can be controlled more precisely, taking into consideration the amount of light coming in from a window, for example. 
     In the present embodiment, if the identified instruction indicates the brightness detection mode, instruction controller  114  causes first communicator  115  to transmit control information  119  which includes a parameter indicating a target value representing target brightness. If the address indicated in control information  119  matches the own address and control information  119  indicates the brightness detection mode, dimming controller  124  controls dimming to make the brightness which is detected by sensor device  121  approximate to the target value indicated by the parameter. 
     In this manner, for example, if lighting system  100  is installed in a space where precise operations are performed, the target value is set to a comparatively large value, thus maintaining the brightness of the space suitable for the precise operations. 
     Lighting system  100  according to the embodiment may have a configuration for controlling dimming of plural lighting devices  150  other than the configuration described with reference to  FIGS. 1A to 6 . The following describes variations of lighting system  100 , focusing on differences in configuration from the above-described embodiment. 
     Variation 1 
       FIG. 7  illustrates an example of schedule information  200   a  and an example of parameter information  210  according to Variation 1 of the embodiment. 
     In schedule information  200   a  illustrated in  FIG. 7 , parameters for the human detection mode and the brightness detection mode are designated by symbols (a to e), and parameter information  210  includes parameters (numerical values) corresponding to the symbols. 
     Note that schedule information  200   a  according to this variation is associated with at least one of addresses “01” and “02.” For example, if schedule information  200   a  is associated with address “01”, schedule information (not illustrated) associated with address “02” is further stored in schedule storage  112 . The same also applies to schedule information  200   b  according to Variation 2 described below. 
     Parameter information  210  indicates parameters associated with periods. Specifically, parameter information  210  indicates various parameters associated with periods in units of month, such as a period from January to March. 
     In this variation, timer  111  of system control device  110  outputs a counter value indicating a time and at least day and month of a date. For example, timer  111  outputs a counter value which includes a date and a time (for example, “2015.01.30, 12:58”). 
     Instruction controller  114  of system control device  110  reads, from parameter information  210 , a parameter associated with a period which includes at least one of month and day indicated by a counter value, and causes first communicator  115  to transmit control information  119  which includes the read parameter. 
     For example, when a counter value output from timer  111  indicates “2015.01.30, 10:00”, instruction controller  114  reads the “brightness mode” and “target value: c” associated with time “10:00” from schedule information  200   a . Instruction controller  114  further reads, from parameter information  210 , parameter “700 lx” associated with “January” which is the month indicated by the counter value and “target value: c” read from schedule information  200   a.    
     Instruction controller  114  causes first communicator  115  to transmit control information  119  which includes the instruction identified as described above (“brightness detection mode” and “700 lx”), and one or more addresses associated with schedule information  200   a.    
     Second communicator  125  of each of lighting control devices  120  receives control information  119  transmitted from first communicator  115 . As a result, one or more lighting control devices  120  each having an own address that matches one of one or more addresses indicated in control information  119  perform operation as follows. Specifically, dimming controller  124  controls dimming of four lighting devices  150  to make the brightness which is detected by sensor device  121  approximate to the target value “700 lx” (see  FIG. 6 ). 
     As described above, system control device  110  has schedule information  200   a  designating a mode for each time of day, and parameter information  210  designating a parameter for use in each mode for each period. In this manner, for example, system control device  110  can provide, for each season for the same mode, lighting control device  120  with a parameter suitable for the season. 
     For example, parameter information  210  illustrated in  FIG. 7  shows that a dimming level for when a person is detected is “80%” in a period from December to March next year (winter period), and is “70%” in a period from April to November (spring to autumn period), in the human detection mode executed during the morning. 
     In other words, in the spring to autumn period when the sun rises earlier than winter, securing brightness necessary for human activity and reduction in power consumption can be both achieved by making the dimming level for when a person is detected in this period lower than the dimming level for the winter period. 
     In this manner, lighting system  100  according to this variation can more precisely adjust dimming control parameters which are given to lighting control devices  120 , according to, for example, a change in natural environment, thus saving more energy, for example. 
     Note that although the dimming level for the dimming level fixed mode is fixed at “0%” in  FIG. 7 , parameter information  210  may define, also for the dimming level designated in the dimming level fixed mode, different values for periods as with parameters for other modes. 
     Furthermore, time-series sections in parameter information  210  may not be in units of month, and may be in units of day, units of year, or units of day of week. 
     In first schedule information  201  and second schedule information  202  according to the above embodiment, various parameters may be designated by symbols (a to e) so that various parameters are identified using parameter information  210 . 
     Variation 2 
       FIG. 8  illustrates an example of schedule information  200   b  and an example of time-of-day information  212  according to Variation 2 of the embodiment. 
     Schedule information  200   b  illustrated in  FIG. 8  includes instructions directed to lighting control devices  120 , and identifiers (( 1 ) to ( 4 )) associated with the instructions and tied with times. Time-of-day information  212  includes times associated with the identifiers. 
     Time-of-day information  212  indicates times of day associated with periods and identifiers. Specifically, periods in units of month, such as a period from January through May, are associated with times of day associated with identifiers, such as 22:00 to 24:00, in time-of-day information  212 . 
     In this variation, timer  111  of system control device  110  outputs a time and at least month and day of a date. 
     Instruction controller  114  of system control device  110  identifies, from time-of-day information  212 , an identifier for a period which includes at least one of month and day indicated by a counter value and a time indicated by the counter value. 
     Instruction controller  114  further identifies, from schedule information  200   b , a mode associated with the identified identifier, for instance. 
     For example, if a counter value output from timer  111  shows “2015.01.30, 10:00”, instruction controller  114  identifies “(2)” which is an identifier corresponding to January and 10:00, from time-of-day information  212 . 
     Instruction controller  114  further identifies, from schedule information  200   b , “human detection mode”, “70%”, and “5%”, which are included in an instruction associated with identifier “(2).” Instruction controller  114  causes first communicator  115  to transmit control information  119  which includes the identified instruction (“human detection mode”, “70%”, and “5%”), and one or more addresses associated with schedule information  200   b.    
     Second communicator  125  of each of lighting control devices  120  receives control information  119  transmitted from first communicator  115 . As a result, one or more lighting control devices  120  each having an own address that matches one of one or more addresses indicated in control information  119  perform operation as follows. Specifically, dimming controller  124  controls dimming of four lighting devices  150 , in accordance with the result of human detection by sensor device  121  (see  FIG. 5 ). 
     As described above, system control device  110  according to this variation has schedule information  200   b  which specifies instructions associated with times of day, and time-of-day information  212  which specifies times of day associated with periods. Accordingly, for example, in the case where lighting control devices  120  are each caused to execute a predetermined mode during a predetermined time of day, the predetermined time of day can be changed, extended, or shortened to fall within a range suitable for a season. 
     For example, time-of-day information  212  illustrated in  FIG. 8  defines morning hours (a time of day indicated by identifier ( 2 )) of a period (June to September) which includes summer, one hour earlier than morning hours of other periods (January to May, and October to December). 
     In other words, by setting morning hours slightly earlier for a period (June to September) when the sun rises comparatively early in a year, lighting control device  120  can control dimming in an appropriate mode that suits a time when a person starts activity, for example. 
     Note that first schedule information  201  and second schedule information  202  according to the above embodiment may be each configured to refer to times of day specified by time-of-day information  212 . 
     Note that first schedule information  201  and second schedule information  202  according to the above embodiment may each include identifiers (( 1 ) to ( 4 )) so that time-of-day information  212  specifies times of day assigned to various modes. 
     Variation 3 
       FIG. 9  illustrates system control device  110  and communication terminal  300  according to Variation 3 of the embodiment. 
       FIG. 10  illustrates an example of a lighting system setting screen displayed on communication terminal  300  according to Variation 3 of the embodiment. 
     In system control device  110  according to Variation 3 illustrated in  FIG. 9 , first communicator  115  receives setting information for controlling operation of at least one lighting device  150 , which is transmitted from communication terminal  300 . 
     Instruction controller  114  generates or updates schedule information  200 , using the setting information received by first communicator  115 , and causes schedule storage  112  to store generated or updated schedule information  200 . 
     Communication terminal  300  is a terminal device having an information display function, and can be achieved by a smartphone, a tablet terminal, or a personal computer, for example. Communication terminal  300  has display panel  310 , a CPU, a communication interface, and others, and a function of executing an application program. 
     How information is transmitted and received by communication terminal  300  and first communicator  115  is not particularly limited, and one of various communication standards, such as Wi-Fi (registered trademark) and Bluetooth (registered trademark), is used to transmit and receive information. 
     The matters with regard to communication terminal  300  described above also apply to Variations 4 and 5 later described. 
     In this variation, communication terminal  300  is a mobile terminal device typically called a smartphone, and has an application program for setting details of schedule information  200 . Communication terminal  300  displays, on display panel  310 , for example, a lighting system setting screen (hereinafter, referred to as “setting screen”) as illustrated in  FIG. 10 , as a user interface. 
     For example, a user designates an address associated with a schedule for which setting is to be made and modes for times of day via a setting screen, and performs a predetermined operation such as pressing a transmission button displayed on the setting screen, thus transmitting information indicating, for instance, the address and the modes designated via the setting screen, to system control device  110  as setting information. In this variation, setting information is transmitted from communication terminal  300  to system control device  110  through wireless communication. 
     Note that although  FIG. 10  illustrates a screen for a user to select a mode for a fixed time of day such as “morning: 6-11”, the user may make selection or input for items other than modes. 
     For example, the start and the end of a time of day may be displayed on the setting screen as items that can be selected or input by a user. Furthermore, a set (hereinafter, referred to as a “mode set”) that includes times of day and modes associated with the times of day may be transmitted to system control device  110  as setting information, by a user simply selecting or inputting a setting name such as “summer setting” or “energy saving priority setting.” 
     Note that communication terminal  300  may transmit, to system control device  110 , information indicating a setting name, such as “summer setting” or “energy saving priority setting”, as setting information. In this case, if system control device  110  has stored a mode set corresponding to the setting name, instruction controller  114  can identify a mode set for use in generation or update of schedule information  200 , according to the setting name indicated by the setting information. 
     Accordingly, in this variation, schedule information  200  is generated or updated based on setting information transmitted from communication terminal  300 . This allows, for instance, schedule information  200  to be generated with use of, for example, a multifunctional inputter (such as a software/hardware keyboard) included in communication terminal  300 . 
     Thus, efficiency of generation or update of schedule information  200  is increased, and thus schedule information  200  can be readily edited according to a time of day or a season, for example. 
     Variation 4 
       FIG. 11  illustrates system control device  110  and communication terminal  300  according to Variation 4 of the embodiment. 
       FIG. 12  illustrates an example of a schedule confirmation screen displayed on communication terminal  300  according to Variation 4 of the embodiment. 
     In system control device  110  according to Variation 4 illustrated in  FIG. 11 , first communicator  115  transmits at least a part of schedule information  200  stored in schedule storage  112 , to communication terminal  300 . 
     In this variation, communication terminal  300  has an application program for requesting schedule confirmation information and generating a schedule confirmation screen, using the received schedule confirmation information. 
     The user performs a predetermined operation such as pressing a request button displayed after the application program is activated, for example. In this manner, communication terminal  300  transmits, to system control device  110 , a request for schedule confirmation information. 
     If first communicator  115  receives the request, instruction controller  114  reads at least a part of schedule information  200  from schedule storage  112 . First communicator  115  transmits the at least one read part to communication terminal  300  as schedule confirmation information. 
     Note that if a part of schedule information  200  is transmitted as schedule confirmation information, instruction controller  114  may transmit to communication terminal  300 , using first communicator  115 , a predetermined portion of schedule information  200  on the basis of the current time, for example. 
     Furthermore, instruction controller  114  may transmit, to communication terminal  300  using first communicator  115 , for example, only a portion of schedule information  200  (for example, only first schedule information  201 ) which is associated with the address designated in a request from communication terminal  300 . 
     In this manner, schedule confirmation information is transmitted from system control device  110  to communication terminal  300 , and thus communication terminal  300  can display, on display panel  310 , a schedule confirmation screen as illustrated in  FIG. 12 , for example. 
     The schedule confirmation screen illustrated in  FIG. 12  shows schedules for switching between modes on a single day, which are associated with the addresses, and indicates where in the schedules the current time is at. 
     In this manner, the user can check with ease which mode is used to control dimming of plural lighting devices  150  throughout the day. Furthermore, the example illustrated in  FIG. 12  shows that a user can check which mode is currently used to control dimming of plural lighting devices  150 . 
     This consequently facilitates checking whether the entire schedule which has been set at the point in time is appropriate or whether a dimming control mode being executed at the point in time is appropriate, for example. 
     Note that although the schedule confirmation screen in  FIG. 12  shows text which identifies types of modes such as “human” and “brightness”, these do not need to be expressed by text and, for example, icons associated with such modes may be displayed on the schedule confirmation screen. 
     Further, the schedule confirmation screen may show parameters used for modes (a dimming level for when a person is detected or a target value of brightness). 
     Furthermore, for example, a predetermined user operation may switch between and display a schedule associated with address “01” and a schedule associated with address “02”, on the schedule confirmation screen. 
     First communicator  115  may transmit schedule confirmation information to communication terminal  300 , independently of a request from communication terminal  300 . First communicator  115  may transmit schedule confirmation information, for example, at regular intervals or upon the occurrence of an event, such as switching between modes (transmission of control information  119 ), which is a trigger. 
     Variation 5 
       FIG. 13  illustrates lighting control device  120  and communication terminal  300  according to Variation 5 of the embodiment. 
       FIG. 14  illustrates an example of a mode confirmation screen displayed on communication terminal  300  according to Variation 5 of the embodiment. 
     Note that although the following describes a mode information transmitting function of lighting control devices  120 , not all lighting control devices  120  included in lighting system  100  need to have this mode information transmitting function. Only one of plural lighting control devices  120  may have the mode information transmitting function described in this variation. 
     Second communicator  125  of lighting control device  120  according to Variation 5 illustrated in  FIG. 13  transmits, to communication terminal  300  which communicates with second communicator  125 , mode information indicating which mode among the human detection mode, the brightness detection mode, and the dimming level fixed mode dimming controller  124  is executing. 
     In this variation, communication terminal  300  has an application program for requesting mode information and generating a mode confirmation screen, using the received mode information. 
     For example, a user performs a predetermined operation such as pressing a request button which is displayed after the application program is activated. In this manner, communication terminal  300  transmits to system control device  110  a request for mode information. 
     If second communicator  125  receives the request, dimming controller  124  of lighting control device  120  transmits, to communication terminal  300 , mode information which indicates a mode that is being executed at the point in time (mode identification information such as a mode name or a mode ID), using second communicator  125 . Mode information also includes lighting control device  120 . 
     In this manner, communication terminal  300  which has received the mode information can display a mode confirmation screen as illustrated in  FIG. 14  on display panel  310 , for example. 
     The mode confirmation screen illustrated in  FIG. 14  shows identification information of lighting control device  120  (“lighting control device A” in this variation), and which mode is currently being executed. Furthermore, this mode confirmation screen shows that the human detection mode is being executed, a person has been detected by this moment, and the dimming level is “70%.” In other words, the mode information transmitted from second communicator  125  includes information such as a dimming level at the time when the request is transmitted. 
     In this manner, the user can check with ease the type of a current mode being executed by one lighting control device  120  and the details of the mode, thus facilitating checking whether the dimming control mode being executed at the point in time is appropriate. 
     Note that although the mode confirmation screen illustrated in  FIG. 14  shows a current state such as a dimming level as well, communication terminal  300  may output information indicating at least a mode that is being currently executed, based on the received mode information. 
     Furthermore, system control device  110  may be a transmitter of mode information, rather than lighting control device  120 . In other words, system control device  110  includes timer  111  for checking the current time and schedule information  200  which includes an instruction directed to lighting control device  120 . 
     Accordingly, system control device  110  can be indirectly informed of which mode lighting control device  120  having the address is executing, using the address included in a request from communication terminal  300 , for example. Accordingly, system control device  110  can transmit, to communication terminal  300 , mode information indicating a mode which specific lighting control device  120  is executing. 
     Specifically, first communicator  115  of system control device  110  may transmit, to communication terminal  300 , mode information indicating which mode among the human detection mode, the brightness detection mode, and the dimming level fixed mode dimming controller  124  included in one of plural lighting control devices  120  is executing. 
     Note that first communicator  115  or second communicator  125  may transmit mode information to communication terminal  300 , independently of a request from communication terminal  300 . First communicator  115  or second communicator  125  may transmit mode information at regular intervals, for example. 
     Furthermore, for example, second communicator  125  may transmit mode information upon a change in a dimming level in a certain mode or the occurrence of an event such as switching between modes, which is a trigger. 
     Variation 6 
       FIG. 15  illustrates a flow of instruction information  129  in subsystem  101   d  according to Variation 5 of the embodiment. 
     Note that although the following describes an individual control function of one subsystem (subsystem  101   d ) to control plural lighting devices  150  separately, plural subsystems may have the individual control function. For example, all subsystems  101   a  to  101   d  may have the individual control function. 
     Subsystem  101   d  according to this variation includes lighting control device  120  (lighting control device D in this variation), and plural lighting devices  150  (La to Ld) each having an assigned device address and connected to lighting control device  120 . In this variation, different device addresses (001 to 004) are assigned to plural lighting devices  150  (La to Ld). 
     Dimming controller  124  of lighting control device  120  transmits, to plural lighting devices  150 , instruction information  129  which includes at least one device address among the device addresses and information indicating a dimming level. In this manner, dimming of at least one lighting device  150  having the at least one device address is controlled. 
     Specifically, in subsystem  101   d  according to this variation, lighting circuit  152  included in each of plural lighting devices  150  receives instruction information  129  transmitted from lighting control device  120 . When the at least one device address indicated in instruction information  129  includes the device address of lighting device  150  among lighting devices  150 , lighting circuit  152  of lighting device  150  causes light source  155  of lighting device  150  to provide illumination at the dimming level indicated by instruction information  129 . 
     In the example illustrated in  FIG. 15 , instruction information  129  includes two destination device addresses “003” and “004”, and “70%” indicating a dimming level. 
     In this case, four lighting devices  150  receive instruction information  129  transmitted from lighting control device  120 . However, lighting device  150  (lighting device La) to which address “001” is assigned and lighting device  150  (lighting device Lb) to which address “002” is assigned ignore the instruction indicated in instruction information  129 , because the destination device addresses do not include the device addresses of lighting devices La and Lb. 
     In contrast, lighting device  150  (lighting device Lc) to which device address “003” is assigned and lighting device  150  (lighting device Ld) to which device address “004” is assigned execute the instruction indicated in instruction information  129 , because the destination device addresses include the device addresses of lighting devices Lc and Ld. 
     As a result, for example, the dimming level of lighting devices La and Lb is not changed, while the dimming level of lighting devices Lc and Ld is changed to “70%.” 
     As described above, lighting control device  120  can control dimming of plural lighting devices  150  differently from one another. 
     This feature is useful in scenes as follows, for example. Now, assume the case where a person enters subregion  501   d  in which no person was present, as illustrated in  FIG. 15 , during a period when lighting control device  120  is executing the human detection mode. 
     In the assumed case, subregion  501   d  where subsystem  101   d  is disposed is divided into four individual regions ( 502   a  to  502   d ) as illustrated in  FIG. 15 , and sensor device  121  detects a person in and brightness of each of the individual regions ( 502   a  to  502   d ). 
     In this state, four lighting devices  150  provide illumination at a dimming level of “5%” before a person enters subregion  501   d . Later, sensor device  121  detects the presence of the person in individual region  502   d . Dimming controller  124  causes second communicator  125  to transmit instruction information  129  for changing the dimming level of lighting devices Ld and Lc which illuminate individual regions  502   d  and  502   c  to “70%”, based on the detection result. 
     In other words, instruction information  129  illustrated in  FIG. 15 , whose destination device addresses are lighting devices Ld and Lc, is transmitted to four lighting devices  150 , and only lighting devices Ld and Lc, among four lighting devices  150 , cause light sources  155  to provide illumination at a dimming level of “70%”, in accordance with instruction information  129 . 
     As a result, a predetermined area of subregion  501   d  which includes a position where the person is present is brightly illuminated, and the dimming level of one or more lighting devices  150  in other areas is maintained low. This achieves a partial increase in the brightness of illumination region  500  if necessary, and furthermore saves power consumption of entire lighting system  100 . 
     Note that in the example illustrated in  FIG. 15 , dimming may be controlled to change the dimming level of only lighting device Ld in individual region  502   d  where the person is detected to “70%”, among four individual regions ( 502   a  to  502   d ). 
     Furthermore, different device addresses are not necessarily assigned to lighting devices La to Ld. For example, the same device address may be assigned to two or more lighting devices  150  for which dimming control for the same mode needs to be performed in synchronization. 
     For example, in the brightness detection mode, dimming controller  124  can also give an instruction indicating different dimming levels to four lighting devices  150 , based on the detection results of brightness of four individual regions ( 502   a  to  502   d ) obtained by sensor device  121 . In this manner, for example, the brightness of the individual regions can be equalized although the individual regions are under different conditions such as how much natural light comes in. 
     OTHER EMBODIMENTS 
     Although the above has described lighting devices based on an embodiment and variations thereof, the lighting devices are not limited to the embodiment and the variations. 
     For example, in  FIG. 4 , schedule information  200  includes first schedule information  201  and second schedule information  202  which clearly show schedules associated with two addresses “01” and “02”, respectively. 
     However, aspects of schedule information  200  are not limited to the above described aspect. For example, schedule information  200  may have information indicating associations of instructions and times, which is used in common by four lighting control devices  120  according to the embodiment described above. 
     In this case, instruction controller  114  may operate in accordance with a rule specifying that transmission of an instruction to address “02” is prevented during a period from 6:00 to 21:00, for example. In this case, only “01” is designated as a destination address of an instruction given during the period from 6:00 to 21:00 and indicated in schedule information  200 . As a result, lighting control devices  120  (A and B) having address “01” and lighting control devices  120  (C and D) having address “02” can be caused to execute different modes during the same time of day. 
     For example, if schedule information  200  indicates when to switch between modes in units of time, the time indicated by a counter value output from timer  111  may indicate at least hour of the time including hour, minute, and second. 
     Furthermore, schedule information  200  does not need to include parameters as illustrated in  FIG. 4 , for example. Assume an example of the case where lighting control device  120  stores parameters such as dimming levels or target illuminance for when a person is detected and for when no person is detected. In this case, if lighting control device  120  receives information for identifying a mode to be executed from system control device  110 , lighting control device  120  can execute the mode using one or more parameters suitable for the mode. 
     In the human detection mode, a dimming level may be changed to three levels or more, for example. For example, if many people are detected, control for increasing the dimming level may be performed. Furthermore, if sensor device  121  detects a person in the human detection mode, sensor device  121  may output a detection result which indicates the state of the detected person. For example, if sensor device  121  detects a person, sensor device  121  may output a detection result that is more specifically classified, such as a detection result indicating that the detected person is not moving or is moving. 
     In this case, dimming controller  124  may control dimming using different dimming levels when the detection result output from sensor device  121  indicates that the detected person is moving and that the detected person is not moving. Further, system control device  110  may transmit such dimming levels to lighting control device  120 . 
     In other words, if the instruction identified from schedule information  200  shows the human detection mode, instruction controller  114  of system control device  110  may cause first communicator  115  to transmit control information  119  which includes a parameter indicating a dimming level based on a state of a person when he/she is detected or a dimming level for when no person is detected. 
     Separate storage devices may store schedule information  200  and other information, such as parameter information  210  and time-of-day information  212 . 
     A parameter such as a dimming level for each mode and a time of day assigned to each mode may be both arbitrarily determined in a schedule of dimming control which is to be executed by lighting control device  120 . In other words, lighting system  100  may have features of both Variations 1 and 2. 
     Furthermore, an instruction given from system control device  110  and directed to lighting control device  120  may not explicitly show a mode to be executed by lighting control device  120 . For example, if control information  119  includes information indicating that a target value is “500 lx”, lighting control device  120  can determine that the brightness detection mode is to be executed. Similarly, if control information  119  includes information indicating two dimming levels, lighting control device  120  can determine that the human detection mode is to be executed. Furthermore, if control information  119  includes only one dimming level, lighting control device  120  can determine that the dimming level fixed mode is to be executed. 
     Light source  155  included in lighting device  150  may not include one or more LEDs. For example, one or more fluorescence tubes may be employed as light source  155 . Furthermore, light emitting elements, such as semiconductor light emitting elements including a semiconductor laser, organic electroluminescence (EL), and inorganic EL, may be employed as light source  155 . 
     Further, the present disclosure can be achieved as a program for causing a computer to execute distinctive processing that is performed by at least one of system control device  110  and lighting control device  120 . Such a program can be distributed via a recording medium such as CD-ROM and a transmission medium such as the Internet. 
     The present disclosure may also include embodiments as a result of adding, to the embodiments, various modifications that may be conceived by those skilled in the art, and embodiments obtained by combining constituent elements and functions in the embodiments in any manner without departing from the spirit of the present disclosure. 
     While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all modifications and variations that fall within the true scope of the present teachings.