JP4717432B2 - Lighting control device - Google Patents

Description

  The present invention relates to an illumination control device, and more particularly, to an illumination control device that can detect disconnection of a light bulb.

  A dimming control device that controls the illuminance of a light bulb such as an incandescent light bulb is conventionally realized by using a switching element such as a triac or a thyristor. For example, a commercial AC power supply is connected to both ends of a series circuit in which a triac is connected to a light bulb, a triac gate pulse is supplied in synchronization with the positive / negative voltage of the AC power supply, the triac is turned on, and the supply timing of the gate pulse is determined. Adjust the amount of time the bulb is on by changing it.

In addition, a drive circuit that enables multi-tone brightness control of a cold cathode discharge tube has been proposed (for example, Patent Document 1). Furthermore, a disconnection alarm device that detects disconnection of the heater of the thermostatic chamber has been proposed (for example, Patent Document 2). And the illuminating device which can prevent the loose contact mode which a terminal part heats by the incomplete contact of an illuminating device is proposed.
Japanese Patent Laid-Open No. 7-106089 Japanese Patent Laid-Open No. 11-83927 JP-A-9-204987

  It is required to add a function for detecting the presence or absence of disconnection of a light bulb to the dimming control device. For example, in order to detect disconnection of a light bulb that is a load, it is only necessary to detect the presence or absence of the current of the load, but since no current flows to a light bulb that is in the off state or 0% dimming state, The disconnection state cannot be detected from the presence or absence of the current. Although a method of monitoring the presence or absence of a load current by always passing a very small current like a stop lamp of an automobile is conceivable, it is not desirable from the viewpoint of energy saving. There is also a method of detecting that the voltage applied to the switching element becomes zero when the bulb is disconnected by monitoring the voltage at both ends of the switching element, but the switching element itself is always conductive at 100% dimming. In the normal state, the voltage is not applied to the switching element regardless of whether the bulb is disconnected or not, and the disconnection state cannot be detected.

  Accordingly, an object of the present invention is to provide an illumination control device that can easily detect disconnection of a light bulb.

  In order to achieve the above object, according to the first aspect of the present invention, a power supply terminal to which AC power is supplied, an output terminal to which a load element is connected, and the output terminal and the power supply terminal are provided. An AC power supply period to the load element by variably controlling the conduction timing of the switching element. A lighting control device that controls the dimming level by variably controlling the load control means, wherein the load control means has a disconnection detection period in which the conduction of the switching element is not forced regardless of the dimming level. To do.

  In the above aspect, in a more preferable embodiment, the voltage monitoring unit that monitors the voltage across the switching element has voltage monitoring unit, and the voltage monitoring unit applies voltage at least once in the disconnection determination period including the disconnection detection period. Is detected, and the disconnection state of the load element is detected when the voltage monitoring means does not detect voltage application during the disconnection determination period.

  According to another aspect of the present invention, a power supply terminal to which AC power is supplied, an output terminal to which a load element is connected, a switching element provided between the output terminal and the power supply terminal, Load control means for controlling the conduction of the switching element corresponding to the AC power supply, and variably controlling the conduction timing of the switching element to variably control the AC power supply period to the load element to adjust the light. An illumination control device for controlling a level, wherein the load control means is configured to gradually increase the dimming level in the first period when the lighting request is made and the elapsed time from the previous extinction is longer than the reference time. The lighting control is performed, and when the elapsed time from the previous extinction is shorter than the reference time, the lighting control is performed by increasing the dimming level in a period shorter than the first period.

  Furthermore, according to another aspect of the present invention, a power supply terminal to which AC power is supplied, an output terminal to which a load element is connected, a switching element provided between the output terminal and the power supply terminal, Load control means for controlling the conduction of the switching element corresponding to the AC power supply, and variably controlling the conduction timing of the switching element to variably control the AC power supply period to the load element to adjust the light. In the lighting control device for controlling the level, the load control means, when requested to turn on, controls the lighting control or the dimming level while gradually increasing the dimming level in the first period according to the ambient illuminance. A lighting control device, wherein the lighting control device performs any one of the lighting controls by raising in a period shorter than one period.

  According to the first aspect of the present invention, the disconnection state of the load element can be reliably detected by checking the presence / absence of the voltage across the switching element in the disconnection detection period at any dimming level. it can. Therefore, the disconnection state of the load element can be detected without requiring manual check, and the added value of the lighting control device can be increased.

  Further, according to another aspect of the present invention, it is possible to perform lighting control at the time of a lighting request in an optimal manner.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the technical scope of the present invention is not limited to these embodiments, but extends to the matters described in the claims and equivalents thereof.

  FIG. 1 is a circuit diagram of the illumination control device according to the present embodiment. The lighting control device includes a power supply terminal 10 to which commercial AC power is supplied, an output terminal 12 to which an incandescent bulb as a load is connected, and a switching element T1 provided between the output terminal 12 and the power supply terminal 10. Have. The switching element T1 is composed of a bidirectional switching element such as a triac or an element in which thyristors are connected in parallel in the opposite direction. The illumination control device further includes a dimming control circuit 20 as load control means for variably controlling the conduction timing of the switching element T1. The dimming control circuit 20 receives the zero cross point detection signal in from the zero cross point detecting means 22 connected to the power supply terminal 10, and generates an output signal out for making the switching element conductive in synchronization with the timing. It outputs to the means 19 and makes the switching element T1 conduct.

  The zero-cross point detection means 22 includes a photorelay element including a bidirectional light emitting element (for example, LED) connected to the resistors R1 and R2 and a light receiving element connected to the resistor R3, and is applied to the power supply terminal 10. While the commercial AC power supply is positive or negative voltage, the light emitting element emits light, the light receiving element is turned on, the input in is set to L level, and when the commercial AC power supply passes through the zero cross, the light emitting element stops emitting light and receives light The element becomes non-conductive, and the input in is set to H level. That is, the input in is a signal for notifying the zero cross timing of the AC power supply.

  The gate signal generating means 18 is composed of a photorelay element having a light emitting element connected to the resistor R4 and a bidirectional light receiving element connected to the resistors R5 and R6, and performs switching in response to the output signal out. A gate signal is supplied to the gate terminal G of the element T1. The switching element T1 made of triac becomes conductive in response to the gate signal, and becomes non-conductive when the AC power supply is zero-crossed. Both the zero-cross point detection means 22 and the gate signal generation means 18 are arranged so as to insulate the commercial AC power supply (for example, 50 Hz, 100 V) from the DC power supply Vcc (for example, DC 5 V) of the dimming control circuit 20. It is composed of relay elements. The dimming control circuit 20 is composed of a microcomputer that operates with, for example, a DC power supply Vcc of 5V.

  In this illumination control circuit, in response to the zero cross point detection signal in from the zero cross point detection means 22, the dimming control circuit 20 outputs an output signal pulse out for conduction control at a predetermined timing, and in response to this, The gate signal generation means 18 generates a gate signal, and turns on the switching element T1 made of triac. While the switching element T1 is conducting, a current from the AC power source is supplied to the light bulb 14 which is a load element, and the light bulb 14 is turned on. When the AC power supply reaches the zero cross point, the triac is turned off and the light bulb 14 is automatically turned off. Further, in the next period, when a new output signal out is generated, the light bulb 14 is turned on and continues to be turned on until the zero cross point of the next AC power supply is reached. Thus, the switching element T1 conducts in the period from the output signal out of the dimming control circuit 20 to the subsequent zero cross point every half cycle of the AC power supply, and turns on the bulb 14 in that period. Therefore, if the timing of the output signal out of the dimming control circuit 20 is advanced, the lighting period can be lengthened and the dimming level can be raised, and if the timing is delayed, the lighting period is shortened and the dimming level is lowered. be able to. Therefore, by variably controlling the timing of the output signal out, it is possible to control the length of the lighting period of the light bulb, which is the load element, and to perform dimming control.

  In the present embodiment, the voltage monitoring means 16 for monitoring the voltage across the switching means T1 is provided. The voltage monitoring means 16 includes a bidirectional light emitting element connected between both ends of the switching means T1 via resistors R7 and R8, and a light receiving element that generates a disconnection detection signal S16 in response to light received from the light emitting element. It is comprised with the photorelay element comprised by these. A DC power source Vcc is connected to the light receiving element via a resistor R9. When the light receiving element receives light and becomes conductive, a current flows through the resistor R9 and outputs an L level. The output of the photorelay element is inverted by the inverter 17 to generate a disconnection detection pulse S16, which is given to the interrupt input terminal int of the dimming control circuit 20 which is a microcomputer. Therefore, when a voltage is applied between the switching means T1, the inverter 17 outputs an H level disconnection detection signal S16.

  Then, in order to make it possible to detect the disconnection state of the light bulb 14 that is the load element, the dimming control circuit 20 that performs dimming control detects disconnection that does not forcibly conduct the switching element regardless of the dimming level. Have a period. That is, the commercial AC power supply has a frequency of 50 Hz (or 60 Hz), and the dimming control circuit 20 receives the zero cross point detection signal in every 10 msec which is a half cycle. Then, the dimming control circuit 20 outputs the output signal out at a timing corresponding to the dimming level in response to the zero cross point detection signal in. However, regardless of the dimming level, the dimming control circuit 20 has a disconnection detection period in which the output signal out is not output at a cycle longer than the cycle of the zero cross point. During this disconnection detection period, the output signal out is not output, and during that period, the switching means T1 is forcibly turned off, and a voltage can be applied to both ends of the switching means T1 at any dimming level. A state, that is, a state in which a voltage can be applied to the voltage monitoring unit 16 is generated.

  Therefore, if the light bulb 14 which is a load element is in a conductive state, a voltage is applied to both ends of the switching means T1 in the disconnection detection period, the voltage monitoring means 16 detects the voltage, the light emitting element emits light, and the light receiving element Conduction is performed, and the disconnection detection signal S16 is set to the H level. On the other hand, if the light bulb 14 serving as the load element is in a disconnected state, no voltage is applied to both ends of the switching means T1 during the disconnection detection period, so that the voltage monitoring means 16 does not detect voltage application and the light emitting element does not emit light. In addition, the light receiving element is not conducted, and the disconnection detection signal S16 is maintained at the L level. When the AC power supply is in the vicinity of the zero cross point, the voltage applied to the switching element T1 is low, and the voltage monitoring unit 16 sets the disconnection detection signal S16 to the L level, but the bulb 14 is in the conductive state during the disconnection detection period. For example, voltage application is detected and the disconnection detection signal S16 is set to H level. However, if the light bulb 14 is in a non-conductive state, voltage application cannot be detected and the disconnection detection signal S16 remains at L level.

  Hereinafter, the operation of the illumination control circuit in the present embodiment will be described for each dimming level. FIG. 2 is an operation waveform diagram when the dimming level is 0%. In the drawing, the horizontal axis represents time, and the operation on the left side of the bulb is in a normal state, and the operation on the right side of the bulb is in a disconnected state. First, the commercial AC power supplied to the power terminal ACIN is a 50 Hz 100 V AC power source. Although not shown, the zero cross point detection signal in is supplied to the dimming control circuit 20 every time the AC power supply ACIN passes through the zero cross, that is, every half cycle. Since the light control level is 0%, the output signal out is not generated in response to the zero cross point detection signal in. Accordingly, the switching means T1 does not conduct and is always controlled to a non-conducting state.

  Since the switching means T1 is non-conductive in the normal state of the left light bulb, the applied AC voltage is not applied to the low resistance light bulb 14, but is applied to the high resistance switching means T1. Therefore, the monitoring voltage at both ends of the light emitting element of the voltage monitoring means 16 becomes the same as the input AC voltage, the light emitting element emits light during the period when the monitoring voltage exceeds the threshold level of the light emitting element, and the disconnection detection signal S16 becomes H level. Become. However, before and after the monitoring voltage becomes zero cross, the light emitting element is in a non-light emitting state, and the disconnection detection signal S16 becomes L level. That is, the disconnection detection signal S16 becomes H level every half cycle of the input AC signal.

  On the other hand, in the light bulb disconnection state on the right side, no voltage is applied to the switching means T1, and the monitoring voltage across the light emitting element of the voltage monitoring means 16 becomes zero. Therefore, the disconnection detection signal S16 is maintained at the L level.

  FIG. 3 is an operation waveform diagram when the light control level is 10%. Also in this figure, the operation of the light bulb in the normal state is shown on the left side, and the operation of the light bulb in the disconnected state is shown on the right side. Since the dimming level is 10%, the dimming control circuit 20 sets the output signal out to the H level at a predetermined late timing in response to the zero cross point detection signal in. In response to the H level of the output signal out, the gate pulse of the switching means T1 is generated, and the switching means T1 becomes conductive. Then, the switching means T1 becomes non-conductive at the zero cross point of the AC power supply after being conductive. Therefore, the load voltage ACOUT to the light bulb 14 as a load is in a power supply enabled state in the last period of the half cycle of the AC power supply, as shown in the figure.

  Therefore, in the normal state of the left bulb, the load voltage ACOUT is generated in a short period in which the switching means T1 is conductive. In other periods, the switching means T1 is non-conductive and the monitoring voltage is applied to the voltage monitoring means 16. The Accordingly, an H level disconnection detection signal S16 is generated. On the other hand, in the light bulb disconnection state on the right side, the switching means T1 is controlled to be conductive or nonconductive, but since the light bulb 14 is in a disconnected state, no voltage is applied to the switching means T1 and the monitoring voltage becomes zero. Therefore, when the light bulb 14 is in a disconnected state, the disconnection detection signal S16 does not become H level.

  In the present embodiment, the dimming control circuit 20 serving as the load control means has a disconnection detection period TX in which the switching element T1 is not forcibly conducted regardless of the dimming level. The disconnection detection period TX is generated with a frequency of once in a relatively long period in order to minimize the influence on the dimming level. In the disconnection detection period TX, the dimming control circuit 20 outputs the output signal out. Is not output. In the present embodiment, the output signal out is not output during one half cycle of the AC power supply, and the switching means T1 is turned off. This disconnection detection period TX is provided, for example, at a frequency of once every few seconds for an AC power supply of 50 Hz.

  In the disconnection detection period TX, since the switching means T1 is not conducted, the monitoring voltage is the same as that of the AC power source as indicated by 100 in the figure in the normal state of the bulb, and the disconnection detection signal S16 is generated correspondingly. In the light bulb disconnection state, the disconnection detection signal S16 is not generated because the monitoring voltage is zero even if the switching means T1 is not conducted.

  FIG. 4 is an operation waveform diagram when the light control level is 50%. Also in this figure, the operation of the light bulb in the normal state is shown on the left side, and the operation of the light bulb in the disconnected state is shown on the right side. Although the operation is the same as that of FIG. 3 with a dimming level of 10%, the rising timing of the output signal out of the dimming control circuit 20 is earlier because the dimming level is as high as 50%. Accordingly, the ratio between the load voltage and the monitoring voltage is different. The rest is the same as FIG.

  In FIG. 4, since the output signal out is not output in the disconnection detection period TX, the monitoring voltage becomes equal to the AC voltage in the normal state of the bulb, and the monitoring voltage becomes zero in the disconnection state of the bulb. Accordingly, the disconnection detection signal S16 is at the H level when the bulb is in a normal state and remains at the L level when the bulb is disconnected.

  FIG. 5 is an operation waveform diagram when the light control level is 90%. This figure is also the same operation as FIG. 3 with a light control level of 10% and FIG. 4 with a light control level of 50%. However, since the dimming level is as high as 90%, the rising timing of the output signal out of the dimming control circuit 20 is controlled immediately after the zero cross point of the AC power supply ACIN. Therefore, the load voltage ACOUT in the normal state of the bulb is the same as the AC power supply ACIN for a long period of time, and the bulb 14 is lit for a long period of time to achieve a dimming level of 90%.

  On the other hand, as shown in the figure, the monitoring voltage applied to the voltage monitoring means 16 is only an AC voltage applied for a short period in the normal state of the bulb, and the disconnection detection signal S16 is a short H level pulse. Become. However, in the disconnection detection period TX, the switching means T1 is forcibly controlled to be non-conductive, so that the same voltage as the AC power supply is applied in the normal state of the bulb (100 in the figure). As a result, the disconnection detection signal S16 is at the H level for a period of approximately half a cycle. On the other hand, when the light bulb is in a disconnected state, no voltage is applied to the switching unit T1, and the monitoring voltage is zero regardless of the state of the switching unit T1, and thus the disconnection detection signal S16 remains at the L level.

  As shown in FIG. 5, when the dimming level is increased, the monitoring voltage is generated only for a short period even when the bulb is in a normal state, so that the pulse width of the disconnection detection signal S16 is shortened. However, since the switching means T1 is forcibly turned off in the disconnection detection period TX, the monitoring voltage is generated during the normal state of the bulb, and the pulse width of the disconnection detection signal S16 becomes sufficiently long. Therefore, it is possible to appropriately detect the H level of the disconnection detection signal S16 at the interrupt signal terminal int of the dimming control circuit 20 configured by a microcomputer.

  FIG. 6 is an operation waveform diagram when the light control level is 100%. A dimming level of 100% means that the switching means T1 is always maintained in a conductive state. That is, the dimming control circuit 20 controls the output signal out so that it is always maintained at the H level and all the input AC power supply ACIN is applied to the light bulb 14 of the load element. As a result, the resistance of the switching means T1 is always zero or a minute level, and the input AC power supply ACIN remains the load voltage ACOUT as it is regardless of whether the bulb is in a normal state or a disconnected state, and the monitoring voltage is always zero.

  However, in the present embodiment, the disconnection detection period TX is provided with an appropriate period, and during that period TX, the output signal out is set to the L level, and the switching means T1 is forcibly made non-conductive. Thereby, in the normal state of the bulb, as shown by 100 in the figure, the monitoring voltage applied to the voltage monitoring means 16 becomes the same as the input AC power supply, and the disconnection detection signal S16 becomes H level. On the other hand, in the light bulb disconnection state, as shown by 200 in the figure, no voltage is applied to the voltage monitoring means 16, and the disconnection detection signal S16 is maintained at the L level. Therefore, by checking whether or not the disconnection detection signal S16 becomes H level in the disconnection determination period Ty including the disconnection detection period TX, it is possible to detect the disconnection state of the light bulb that is the load element. In addition, at the dimming level of 100%, all the input AC power supply ACIN can be set to the load voltage ACOUT to the light bulb except for the disconnection detection period TX, and the rated power supply can be applied to the load element to the maximum extent. Energy efficiency can be increased.

  In the present embodiment, as shown in FIG. 1, the disconnection detection signal S16 is supplied to the interrupt signal terminal int of the dimming control circuit 20 which is a microcomputer. The dimming control circuit 20 enables the interrupt signal terminal int during at least the disconnection determination period Ty including the disconnection detection period TX, and checks whether an edge signal rising to the H level is input during that period. Therefore, in the case of an intermediate dimming level, for example, as shown in FIG. 4, if a disconnection determination period Ty consisting of a period of a half cycle before and after the disconnection detection period TX is set, a monitoring voltage is generated and the disconnection occurs. When the detection signal S16 generates a rising edge signal even at least once, the dimming control circuit 20 detects the normal state of the bulb. If no rising edge signal is generated even once, the dimming control circuit 20 detects a light bulb disconnection state. In the case of the dimming levels of 0%, 10%, and 90% in FIGS. When the light control level is 100%, as shown in FIG. 6, if the light bulb is in a normal state in the light control determination period Ty, one rising edge is detected and it is determined that there is no disconnection. If so, it is determined that there is a disconnection without detecting the rising edge even once. Therefore, the dimming determination period Ty may be strictly matched with the dimming detection period TX. However, as described above, the dimming determination period Ty can be a slightly longer period including the dimming detection period TX. The interrupt detection operation within 20 can be simplified.

  According to the above embodiment, the disconnection state of the light bulb as a load element can be reliably detected regardless of the dimming level. Therefore, for example, it is possible to automatically detect which bulb is in a disconnected state in a lighting device in a theater. When the dimming control circuit 20 detects a disconnection state, by displaying the disconnection state on a control panel (not shown), it is possible to detect the disconnection of the light bulb on the control panel, and appropriately replace the light bulb. It can be carried out.

  FIG. 7 is a flowchart showing lighting start control in another embodiment. In the above invention, the improved control at the start of lighting will be described using the dimming control function by the dimming control circuit 20 using a microcomputer. FIG. 7 (1) is an example in which the lighting start control is varied according to the length of time that has elapsed since the lights were turned off. In this lighting start control, when a lighting command is received, if the specified time has passed since turning off (YES in S100), dimming to gradually increase the illuminance assuming that the surroundings are dark Lighting is performed under control (S102). That is, the dimming control circuit 20 performs control so that the output timing of the output signal out is gradually advanced from the late timing so that the dimming percent is increased from zero% to 100%. As a result, the stress of lighting on the eyes of those who are present is prevented. In addition, if the specified time has not elapsed after turning off (NO in step S100), it is assumed that the eyes of the person there are accustomed to a bright state, and the dimming control is performed so that the light turns on in a short time. And turn on (S204).

  FIG. 7B is an example of another lighting start control, and is an example in which the lighting start control is varied according to the surrounding brightness. When the lighting command is received, the sensor output from the separately installed illuminance sensor is used to check whether the ambient illuminance is bright (S200). Assuming that the light is lit, the light is controlled so that the light is lit in a short time (S202). If the ambient illuminance is dark, it is assumed that the person in the surrounding area is in a dark state, and the light is controlled to light up gradually so that the illuminance is gradually increased (S204).

  In the lighting start control method in FIG. 7B, steps S202 and S204 may be reversed according to the ambient illuminance. In other words, when a lighting command is received, dimming control is performed so as to gradually increase the illuminance if the surrounding illuminance is high, so that it does not feel a sudden change in illuminance, and if the surrounding illuminance is low, it is predicted to become brighter Assuming that the light is on, turn on the illuminance in a short time.

The above three lighting control examples may be customized in advance by the user, or may be customized according to the place, environment, and usage of lighting control. In any case, by using the dimming control function, the disconnection state of the light bulb can be automatically detected as in the first embodiment, and different lighting start control is performed according to a predetermined condition. Can also be done.

The above embodiment is summarized as follows.

(Supplementary Note 1) A power supply terminal to which AC power is supplied, an output terminal to which a load element is connected, a switching element provided between the output terminal and the power supply terminal, and the switching corresponding to the AC power supply And a load control unit that controls conduction of the element, and variably controls the conduction timing of the switching element to variably control the AC power supply period to the load element to control the dimming level. ,
The load control unit has a disconnection detection period in which the conduction of the switching element is not forcibly performed regardless of the dimming level.

(Appendix 2) In Appendix 1,
Voltage monitoring means for monitoring the voltage across the switching element;
In the disconnection determination period including the disconnection detection period, when the voltage monitoring means detects at least one voltage application, a non-disconnection state of the load element is detected. In the disconnection determination period, the voltage monitoring means An illumination control device, wherein a disconnection state of a load element is detected when application is not detected.

(Appendix 3) In Appendix 1,
The lighting control device according to claim 1, wherein the switching element is turned on in response to a conduction control signal from the load control means, and is turned off in response to a zero cross of the AC power supply.

(Appendix 4) In Appendix 3,
The load control means outputs the continuity control signal after a predetermined time from the zero cross of the AC power supply, and the load control means lowers the dimming level by shortening the dimming level by increasing the predetermined time and dimming by shortening the dimming level. An illumination control device that controls to increase the level.

(Supplementary Note 5) A power supply terminal to which AC power is supplied, an output terminal to which a load element is connected, a switching element provided between the output terminal and the power supply terminal, and the switching corresponding to the AC power supply And a load control unit that controls conduction of the element, and variably controls the conduction timing of the switching element to variably control the AC power supply period to the load element to control the dimming level. ,
The load control means controls the lighting while gradually increasing the dimming level in the first period when the elapsed time from the previous extinction is longer than the reference time when the lighting is requested, and the elapsed from the previous extinction When the time is shorter than the reference time, the lighting control device controls lighting by increasing the dimming level in a period shorter than the first period.

(Appendix 6) A power supply terminal to which AC power is supplied, an output terminal to which a load element is connected, a switching element provided between the output terminal and the power supply terminal, and the switching corresponding to the AC power supply And a load control unit that controls conduction of the element, and variably controls the conduction timing of the switching element to variably control the AC power supply period to the load element to control the dimming level. ,
The load control means, when requested to turn on, raises the light control level while gradually increasing the dimming level in the first period according to the ambient illuminance, or increases the dimming level in a shorter period than the first period. A lighting control device that performs any one of lighting control.

It is a circuit diagram of the illumination control apparatus of this Embodiment. FIG. 6 is an operation waveform diagram at a dimming level of 0%. It is an operation | movement waveform diagram at the time of 10% of light control levels. It is an operation | movement waveform diagram at the time of light control level 50%. It is an operation | movement waveform diagram at the time of 90% of light control levels. It is an operation | movement waveform diagram at the time of light control level 100%. It is a flowchart figure which shows the lighting start control of the illumination in another embodiment.

Explanation of symbols

10: power supply terminal, 12: output terminal, T1: switching element, 16: voltage monitoring means 20: load control means (dimming control circuit), out: conduction control signal, S16: disconnection detection signal

Claims (3)

A power supply terminal to which an AC power supply is supplied; an output terminal to which a load element is connected; a switching element provided between the output terminal and the power supply terminal; and conduction of the switching element corresponding to the AC power supply. and a load control means for controlling for, Te lighting controller odor controlling the variable control to dimming level AC power supply period to the load device by variably controlling the conduction timing of the switching element,
Voltage monitoring means for monitoring the voltage across the switching element;
Before SL load control means, when said power to the load element is supplied, have a disconnection detection period not forcibly performed the conduction of the switching element irrespective of the dimming level,
In the disconnection determination period including the disconnection detection period, when the voltage monitoring unit detects voltage application at least once, a non-disconnection state of the load element is detected. In the disconnection determination period, the voltage monitoring unit applies voltage. A lighting control device, wherein a disconnection state of a load element is detected when no signal is detected. In claim 1,
The lighting control device according to claim 1, wherein the switching element is turned on in response to a conduction control signal from the load control means, and is turned off in response to a zero cross of the AC power supply. In claim 1,
The disconnection detection period has a period longer than a period of a zero cross point of the switching element.

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