JP2008053181A - Dimmer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and inexpensive dimmer capable of preventing unsatisfactory dimming caused by component variations and power supply environments peculiar to a site. <P>SOLUTION: This dimmer is equipped with a zero cross detecting circuit 1b to detect the zero cross point of an input, a control circuit 1a which generates a driving voltage to switch on a TRIAC Q1 and carries out phase control of a DC trigger method in which the driving voltage is continuously given during the ON period of the TRIAC, a target luminance resistor 1c storing data for the target luminance level of an illumination load La, a minimum luminance resistor 1d storing data for the minimum luminance level of the illumination load La, and a switching part 1f to switch a determining mode and a setting mode. The control circuit 1a writes the data of the minimum luminance level in the minimum luminance resistor 1d during the determining mode, controls dimming of the illumination load La so as to achieve the target luminance level during the determining mode, and puts out the illumination load La when the target luminance level is not more than the minimum luminance level. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dimmer.

  Low-voltage mini-halogen lamps are used as high-quality illumination light sources such as store spot lights and downlights. As a lighting device for this low-voltage mini-halogen lamp, an electronic down transformer is used that rectifies a commercial AC voltage (AC 100 V), converts it into a high frequency of several tens of kHz, and further converts it into a high-frequency low voltage of 12 V using a step-down transformer. .

  Further, for the purpose of adjusting the illuminance from the viewpoint of energy saving and production, as shown in FIG. 10, a triac Q100 as a bidirectional switching element is connected in series with an AC power source (commercial power source) AC and an electronic down transformer DT. A dimmer 100 is used in combination with the electronic down transformer DT that configures a closed circuit and makes the effective power to the illumination load La made of a low-voltage mini-halogen lamp variable by making the firing phase angle of the triac Q100 variable. There is a case. An external volume VR100, a resistor R100, and a parallel circuit of a resistor R101 and a capacitor C100 are connected in series between the main electrodes of the triac Q100, and the connection point of the resistors R100 and R101 is connected to the gate terminal of the triac Q100 via the diac Q101. By connecting, a trigger signal for turning on the triac Q100 is generated, and by operating the external volume VR100, the diac Q101 is turned on at a phase timing based on a circuit time constant determined by the external volume VR100, resistors R100 and R101, and the capacitor C100. The triac Q100 is turned on. In this way, by operating the external volume VR100 to control the phase of the triac Q100, the effective power supplied from the commercial power supply AC to the illumination load La is made variable, and dimming control is performed. The electronic down transformer DT and the dimmer 100 are generally used in a catalog or the like in order to prevent inconveniences such as flicker and dimming failure during dimming. .

However, even if the combination of the electronic down transformer DT and the dimmer 100 is suitable, there is a problem such as flickering or poor dimming at the time of dimming due to variations in the parts constituting the electronic down transformer DT and the dimmer 100. In order to solve such a dimming problem, for example, by controlling the firing phase angle of the bidirectional switching element based on the commutation of the current flowing in the closed circuit, There is a dimmer that avoids a control failure during dimming due to phase current (see, for example, Patent Document 1).
JP 2006-32031 A

  However, in Patent Document 1, a current transformer for current detection is required to appropriately control the ignition phase angle, which is a factor in increasing the size and cost of the dimmer.

  Also, depending on component variations and site-specific power supply environments, there are cases in which dimming problems such as flickering and dimming failure cannot be prevented even using conventional technology (for example, starting an electronic down transformer) Dimming failure due to voltage variation).

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a small-sized and low-cost dimmer capable of preventing dimming problems caused by component variations and site-specific power supply environments. .

  The invention of claim 1 is provided with a bidirectional switching element having a self-holding function, and the bidirectional switching element is an AC power supply, and a lighting device that rectifies the input and then converts the input to high-frequency power and supplies it to an illumination load. In a dimmer that makes the effective power to the lighting load variable by making a closed circuit connected in series and making the firing phase angle of the bidirectional switching element variable, zero crossing of the input voltage from the AC power supply Zero-cross detection means for detecting a point, and a DC trigger that generates a drive voltage for turning on the bidirectional switching element in synchronization with the cycle of the AC power supply based on the detection result of the zero-cross detection means, and continues to provide the drive voltage during the on-period Control means for performing phase control of the system, a first register storing data on the target luminance level of the lighting load, and data on the minimum luminance level of the lighting load A second register and mode switching means for switching between a fixed mode and a setting mode, and the control means writes data of the minimum luminance level to the second register in the setting mode, and the target luminance level in the fixed mode. The lighting load is dimmed and controlled so that the lighting load is turned off when the target luminance level is equal to or lower than the minimum luminance level.

  According to the present invention, since the minimum luminance level is set to be changeable, even if there is a variation in the starting voltage of the lighting device due to component variations or a difference in the power supply environment peculiar to the site, flicker at the lower limit of the dimming level is adjusted. Optical failure can be prevented. Further, there is no need for a current transformer for controlling the ignition phase angle of the bidirectional switching element, and the configuration can be reduced in size and cost.

  The invention of claim 2 is provided with a bidirectional switching element having a self-holding function, and the bidirectional switching element is an AC power source, and a lighting device that rectifies the input and then converts it to high-frequency power and supplies it to an illumination load. In a dimmer that makes the effective power to the lighting load variable by making a closed circuit connected in series and making the firing phase angle of the bidirectional switching element variable, zero crossing of the input voltage from the AC power supply Zero-cross detection means for detecting a point, and a DC trigger that generates a drive voltage for turning on the bidirectional switching element in synchronization with the cycle of the AC power supply based on the detection result of the zero-cross detection means, and continues to provide the drive voltage during the on-period Control means for performing phase control of the system, a first register storing data of the target luminance level of the illumination load, and an off timing of the drive voltage with respect to the zero cross point And a mode switching means for switching between the fixed mode and the setting mode, and the control means writes the drive voltage off timing data to the second register in the setting mode. In the fixed mode, the lighting voltage is controlled to be dimmed so that the drive voltage is turned off at the off timing and the target luminance level is reached.

  According to the present invention, the OFF timing of the drive voltage of the bidirectional switching element is set to be changeable, so that it is possible to prevent dimming problems due to the phase advance current even if there are differences in parts and the power environment unique to the site. it can. Further, a current transformer is not required to control the ignition phase angle of the bidirectional switching element, and it can be configured in a small size and at low cost.

  According to a third aspect of the present invention, in the first aspect, data of a target luminance level stored in the first register is set in the definite mode, and data of a minimum luminance level stored in the second register is set in the setting mode. It is characterized by comprising operating means.

  According to the present invention, the target luminance level and the minimum luminance level can be set by the same operation means, and the configuration can be simplified.

  According to a fourth aspect of the present invention, in the second aspect, the data of the target luminance level stored in the first register is set in the fixed mode, and the driving voltage off timing data stored in the second register is set in the setting mode. It is characterized by comprising operating means for setting.

  According to the present invention, the target luminance level and the drive voltage off timing can be set by the same operation means, and the configuration can be simplified.

  The invention of claim 5 includes a bidirectional switching element having a self-holding function, and the bidirectional switching element is an AC power source, and a lighting device that rectifies the input and converts it to high-frequency power and supplies it to an illumination load. In a dimmer that makes the effective power to the lighting load variable by making a closed circuit connected in series and making the firing phase angle of the bidirectional switching element variable, zero crossing of the input voltage from the AC power supply Zero-cross detection means for detecting a point, and a DC trigger that generates a drive voltage for turning on the bidirectional switching element in synchronization with the cycle of the AC power supply based on the detection result of the zero-cross detection means, and continues to provide the drive voltage during the on-period Control means for performing phase control of the system, a first register storing data on the target luminance level of the lighting load, and data on the minimum luminance level of the lighting load A second register, a third register that stores data of driving voltage off timing with respect to the zero-cross point, and mode switching means for switching between the definite mode and the setting mode, and the control means has a minimum in the setting mode. Luminance level data is written to the second register, drive voltage off timing data is written to the third register, and in the fixed mode, the driving voltage is turned off at the off timing and the illumination load is set to the target luminance level. The lighting load is turned off when the target luminance level is less than the minimum luminance level.

  According to the present invention, since the minimum luminance level is set to be changeable, even if there is a variation in the starting voltage of the lighting device due to component variations or a difference in the power supply environment peculiar to the site, flicker at the lower limit of the dimming level is adjusted. Light failure can be prevented, and the drive voltage off timing of the bidirectional switching element is set to be changeable. Can be prevented. Further, there is no need for a current transformer for controlling the ignition phase angle of the bidirectional switching element, and the configuration can be reduced in size and cost.

  As described above, according to the present invention, there is an effect that it is possible to prevent a dimming problem caused by component variations and a site-specific power supply environment, and to be configured in a small size and at a low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a configuration for dimming control of an illumination load La composed of a low-voltage mini-halogen lamp using the dimmer 1 of the present embodiment. The dimmer 1 includes a triac Q1 as a bidirectional switching element. A control circuit 1a that generates a trigger signal for the triac Q1, a zero-cross detection circuit 1b that detects a zero-cross point of an input voltage from an AC power supply (commercial power supply) AC, a target luminance register 1c that stores target luminance data, A minimum luminance register 1d for storing data of minimum luminance and a mode switching unit 1f are provided. Then, the triac Q1 is connected in series with the AC power supply AC and the electronic down transformer DT to form a closed circuit, and the phase control is performed by changing the firing phase angle of the triac Q1, via the electronic down transformer DT. The effective power supplied to the illumination load La is variable, and dimming control is performed. The electronic down transformer DT is a lighting device that rectifies the voltage input via the triac Q1 and converts it to high frequency power, and further converts it to a high frequency low voltage of 12V by a step-down transformer and supplies it to the lighting load La. Constitute.

  A specific circuit configuration of the dimmer 1 is shown in FIG. First, a noise prevention capacitor C1 is connected in parallel between the input terminals to which the AC power supply AC is connected. One end of the capacitor C1 is connected to one end of the AC input terminal of the rectifier circuit 11, and the other end is connected to the other end of the AC input terminal of the rectifier circuit 11 via the fuse F1. A surge absorbing element ZNR is connected in parallel to both ends of the AC input terminal of the rectifier circuit 11, and an electrolytic capacitor C2 is connected to both ends of the DC output terminal via a backflow prevention diode D1. A switching power supply 12 is connected to both ends of the electrolytic capacitor C2. The output voltage of the rectifier circuit 11 is converted into a stable DC low voltage by the switching power supply 12 and supplied to the control microcomputer 13 as the control power supply voltage Vcc.

  In the triac Q1 as a bidirectional switching element for phase control, a series circuit of a phototriac Q4 and resistors R1 and R2 is connected between main electrodes, and a connection point between the resistors R1 and R2 is connected to a gate electrode. . A noise preventing capacitor C3 is connected in parallel between the gate electrode and one main electrode. One output of the AC power supply AC is directly connected to one input of the electronic down transformer DT, and the other output of the AC power supply AC is connected to the other input of the electronic down transformer DT via the triac Q1. The AC power supply AC, triac Q1, electronic down transformer DT, and illumination load La constitute a closed circuit.

  Then, the control microcomputer 13 gives a phase control signal as a drive signal to the triac Q1 in accordance with the target luminance level data stored in the target luminance register 1c and the minimum luminance level data stored in the minimum luminance register 1d. Thus, dimming control is performed on the illumination load La. The target luminance level of the target luminance register 1c and the minimum luminance level of the minimum luminance register 1d are set by the external volume VR1 in the “determined mode” and “setting mode” described later, and the control power supply voltage Vcc is set to the external volume. The voltage is divided by VR1, and the voltage at the voltage dividing point is applied to the A / D conversion input port P3 of the microcomputer 13 through a low-pass filter circuit including resistors R3 and R4 and a capacitor C4. The A / D conversion input port P3 is a port that can acquire a digital value corresponding to the applied voltage. Thereby, the microcomputer 13 can read the data of the target luminance level and the data of the minimum luminance level set by the external volume VR1 as digital values and store them in the target luminance register 1c and the minimum luminance register 1d.

  Then, the microcomputer 13 outputs a phase control signal to the phototriac Q4. Here, as the phase control signal, a DC trigger method (also referred to as a solid trigger method) in which a drive voltage is continuously applied during the ON period is used instead of a pulse trigger method in which a drive voltage is applied only at turn-on. A series circuit of a resistor R5 and a capacitor C5 is connected to the output port P4 for outputting the phase control signal of the microcomputer 13, and the connection point of the resistor R5 and the capacitor C5 is connected to the base of the PNP transistor Q2 for driving the phototriac. Has been. The low-pass filter circuit composed of the resistor R5 and the capacitor C5 is designed to have a time constant that does not cause the PNP transistor Q2 to malfunction due to noise. One end of the light emitting element of the phototriac Q4 is connected to the line of the control power supply voltage Vcc, and the other end is connected to the emitter of the PNP transistor Q2 via the resistor R6. The collector of the PNP transistor Q2 is connected to the ground level (the negative side of the control power supply voltage Vcc).

  When the phase control signal output from the output port P4 becomes L level, the PNP transistor Q2 is turned on, so that the light emitting element of the phototriac Q4 generates a light trigger signal, and the phototriac Q4 is triggered. Further, when the phase control signal output from the output port P4 becomes H level, the PNP transistor Q2 is turned off, the optical trigger signal from the light emitting element of the phototriac Q4 disappears, and the phototriac Q4 is not triggered. When the photo triac Q4 is turned on, the triac Q1 is triggered, and when the photo triac Q4 is turned off, the triac Q1 is not triggered. The triac Q1 is driven by a DC trigger type drive signal by turning on / off the photo triac Q4. Turn on.

  The microcomputer 13 detects the zero-cross point of the voltage of the AC power supply AC by the zero-cross detection circuit 1b, and can output a phase control signal synchronized with the power supply cycle of the AC power supply AC. Here, the configuration of the zero-cross detection circuit 1b will be described. A voltage dividing circuit of resistors R7 and R8 is connected to the DC output terminal of the rectifier circuit 11. A capacitor C6 for preventing noise is connected in parallel across the resistor R8. The potential of the parallel circuit of the resistor R8 and the capacitor C6 is applied between the base and emitter of the transistor Q3. The emitter of the transistor Q3 is grounded, and the collector is pulled up to the level of the control power supply voltage Vcc via the resistor R9. A capacitor C7 for noise prevention is connected in parallel between the collector and emitter of the transistor Q3. The collector of the transistor Q3 is connected to the input port P2 for detecting the zero cross signal of the microcomputer 13.

  When the output voltage of the rectifier circuit 11 is in the vicinity of the zero cross, the bias from the voltage dividing circuit of the resistors R7 and R8 to the transistor Q3 is reduced, and the transistor Q3 is turned off, so that the input port P2 of the microcomputer 13 becomes H level. When the output voltage of the rectifier circuit 11 is not near zero-cross, the transistor Q3 is turned on by the bias applied to the base of the transistor Q3 from the voltage dividing circuit of the resistors R7 and R8, so that the input port P2 of the microcomputer 13 becomes L level. Thereby, the microcomputer 13 can detect the zero cross point of the voltage of the AC power supply AC.

  Further, the microcomputer 13 switches the operation mode between the “determined mode” and the “setting mode” by operating the mode switching unit 1f, and the resistor R10 and the mode switch SW1 are provided between the output terminals of the control power supply voltage Vcc. And a capacitor C8 is connected in parallel to the mode switch SW1. A connection point between the resistor R10 and the mode switch SW1 is connected to the input port P1 of the microcomputer 13. When the mode changeover switch SW1 is turned off, the input port P1 of the microcomputer 13 becomes H level, the microcomputer 13 operates in the “determined mode”, and when the mode changeover switch SW1 is turned on, the input port P1 of the microcomputer 13 becomes L The microcomputer 13 operates in the “setting mode”.

  Further, the microcomputer 13 turns on / off the supply of effective power to the lighting load La by operating the on / off switch SW2, and the resistor R11 and the on / off switch SW2 are provided between the output terminals of the control power supply voltage Vcc. And a capacitor C9 is connected in parallel to the on / off switch SW2. A connection point between the resistor R11 and the on / off switch SW2 is connected to the input port P5 of the microcomputer 13. When the on / off switch SW2 is turned on, the input port P5 of the microcomputer 13 becomes L level, and a phase control signal is output from the microcomputer port P4 to control the lighting load La, and the on / off switch SW2 is turned off. When operated, the input port P5 of the microcomputer 13 becomes H level, the phase control signal from the microcomputer port P4 is stopped, and the illumination load La is turned off.

  The output port P6 of the microcomputer 13 is connected to the control power supply voltage Vcc via the position indicator LED1 and the resistor R12. When the lighting load La is turned off by the operation of the on / off switch SW2, the output port P6 is turned on. Then, the position indicator LED 1 is turned on.

  As shown in FIG. 3, the dimmer 1 is configured by housing the above circuit in a substantially rectangular parallelepiped housing 1j, and is disposed with its front surface exposed in a hole provided on a wall surface or the like, Plate W is provided. A dimming knob 21 for adjusting the resistance value of the external volume VR1 is rotatably attached to the front surface of the housing 1j, and the indicator 22 provided on the dimming knob 21 is rotated within a range of positions 23a to 23c. The slide type operation unit 30 of the mode changeover switch SW1 is disposed on the upper surface of the housing 1j and is operated after the plate W is removed. The push-type operation unit 40 of the on / off switch SW2 is disposed on the front surface of the housing 1j. When the light is turned off, the position indicator LED 1 provided on the operation unit 40 is turned on to notify the position of the operation unit 40. .

  Next, phase control processing by the microcomputer 13 will be described with reference to the flowchart of FIG. First, when the on / off switch SW2 is turned on to start the dimming control of the illumination load La (step S1), the microcomputer 13 detects the voltage signal input to the microcomputer port P3 and determines the digital value. The data is stored in a temporary register (not shown) in the microcomputer 13 (step S2). Next, it is determined from the mode switching signal input to the microcomputer port P1 whether the mode is “confirmed mode” or “setting mode” (step S3).

  In the “determined mode”, the value stored in the temporary register in the microcomputer 13 is transferred to the target luminance register 1c, and is written in the target luminance register 1c as target luminance level data (step S4). Then, the microcomputer 13 generates a phase control signal at an on / off timing corresponding to the target luminance level stored in the target luminance register 1c, and adjusts the illumination load La to the target luminance (step S5).

  As shown in FIG. 5, the target brightness level in the “determined mode” is set as the target brightness level decreases from the maximum brightness level Bmax as the dimming knob 21 is rotated from the position 23c toward the position 23a. The ON period of the phase control signal is shortened, and the luminance level of the illumination load La is lowered. When the dimming knob 21 rotates to the position 23b and the target luminance level falls below the minimum luminance level Bmin stored in the minimum luminance register 1d, the microcomputer 13 turns off the phase control signal and performs illumination. The load La is controlled to be turned off. That is, the lighting load La is turned off while the dimming knob 21 is in the positions 23a to 23b, the lighting load La is turned on at the minimum luminance level Bmin at the position 23b, and the dimming knob 21 is positioned between the positions 23b to 23c. The brightness level is set accordingly.

  Furthermore, in the present embodiment, the minimum luminance level Bmin can be changed in the “setting mode”. In the case of “setting mode” in step S3, the value stored in the temporary register in the microcomputer 13 is transferred to the minimum luminance register 1d and written to the minimum luminance register 1d as data of the minimum luminance level (step S6). Then, the microcomputer 13 generates a phase control signal at an on / off timing corresponding to the minimum luminance level Bmin stored in the minimum luminance register 1d, and adjusts the illumination load La to the minimum luminance (step S5). That is, in the “setting mode”, the dimming lower limit that does not cause flickering or poor dimming can be set by rotating the dimming knob 21 while watching the dimming condition at the actual minimum luminance. . As shown in FIG. 6, the positions 23a to 23c of the operation knob 21 in the “setting mode” correspond to the maximum value B1 to the minimum value B2 of the minimum luminance level, and are rotated from the position 23a toward the position 23c. Accordingly, the minimum luminance level Bmin decreases. When the dimmer 1 is shipped from the factory, the minimum luminance level Bmin is set to the minimum value B2.

  Therefore, by setting the minimum luminance level Bmin to a level at which the output voltage of the dimmer 1 is equal to or higher than the starting voltage of the electronic down transformer DT, the output voltage of the dimmer 1 is smaller than the starting voltage of the electronic down transformer DT. In such a case, the light is turned off, and there are no problems with dimming such as flickering at the lower limit of dimming. In addition, even if there are variations in the starting voltage of the electronic down transformer DT due to component variations or differences in the power supply environment unique to the site, dimming at the lower limit of dimming is possible by changing the minimum luminance level Bmin in the “setting mode”. Problems can be prevented.

  Then, after setting the minimum luminance level Bmin in the “setting mode” and switching to the “determined mode”, the data of the target luminance level stored in the target luminance register 1c and the data of the minimum luminance level stored in the minimum luminance register 1d are obtained. The dimming control is performed with reference.

  Further, no current transformer is required to control the ignition phase angle of the triac Q1, and it can be configured in a small size and at a low cost.

(Embodiment 2)
As shown in FIG. 7, the dimmer 1 according to the present embodiment is different from the first embodiment in that an off timing register 1e is connected to the microcomputer 13 instead of the minimum luminance register 1d. 1 and is not described here.

  The off-timing register 1e stores the off-timing data of the driving voltage with respect to the zero crossing point of the voltage of the AC power supply AC. The microcomputer 13 stores the target luminance level data stored in the target luminance register 1c and the off-timing register. The lighting load La is dimmed and controlled by applying a phase control signal to the triac Q1 in accordance with the off timing data of the drive voltage stored in 1e.

  Next, phase control processing by the microcomputer 13 will be described with reference to the flowchart of FIG. First, when the on / off switch SW2 is turned on to start the dimming control of the illumination load La (step S11), the microcomputer 13 detects the voltage signal input to the microcomputer port P3 and determines the digital value. The data is stored in a temporary register (not shown) in the microcomputer 13 (step S12). Next, it is determined from the mode switching signal input to the microcomputer port P1 whether the mode is “confirmed mode” or “setting mode” (step S13).

  In the “determined mode”, the value stored in the temporary register in the microcomputer 13 is transferred to the target luminance register 1c, and is written in the target luminance register 1c as target luminance level data (step S14). Then, the microcomputer 13 generates a phase control signal at an on timing corresponding to the target luminance level stored in the target luminance register 1c and an off timing stored in the off timing register 1e, and dimmes the illumination load La to the target luminance. (Step S15).

  The off timing is set by the off setting time Toff stored in the off timing register 1e, as shown in the output voltage waveform of the dimmer 1 in FIG. 9A and the phase control signal waveform in FIG. 9B. The next zero-cross point Z is estimated from the zero-cross cycle of the AC power supply AC detected by the zero-cross detection circuit 1b, and the phase control signal is turned off at a timing toff that is earlier than the next zero-cross point Z by the off-set time Toff.

  The target luminance level in the “determined mode” is set by decreasing the target luminance level from the maximum luminance level Bmax to zero as the dimming knob 21 is rotated from the position 23c toward the position 23a. The ON period of the phase control signal is shortened, and the luminance level of the illumination load La is reduced.

  Here, the current flowing through the triac Q1 may be advanced with respect to the voltage phase of the AC power supply AC due to the influence of a capacitive element such as a noise prevention capacitor connected between the input terminals of the electronic down transformer DT. The triac Q1 is an element that is turned off when the phase control signal is turned off and then becomes a current equal to or lower than the holding current. However, the triac Q1 is already turned off at the timing when the phase control signal is turned off due to the influence of the phase advance current. The current flowing through the zero-cross point commutates, and when the current equal to or higher than the holding current flows at the moment when the phase control signal is turned off, the triac Q1 cannot be turned off, so over the next half cycle of the AC power supply AC, The triac Q1 remains on until the current becomes zero, resulting in a dimming problem.

  Therefore, in this embodiment, by setting the off setting time Toff so that the off timing of the phase control signal is before the zero cross point of the current flowing in the triac Q1, even if the above-described phase advance current flows, the triac Q1 is definitely turned off.

  Furthermore, by changing the OFF setting time Toff in the “setting mode”, even if there is a variation in the phase advance current due to differences in component variations or in the power supply environment unique to the site, the current that flows through the TRIAC Q1 when the phase control signal varies Can be always set before the zero cross point, and the setting of the OFF setting time Toff will be described below.

  First, in the “determined mode”, the dimming knob 21 is rotated toward the position 23a, the dimming level is set at a point where the dimming failure occurs in the illumination load La, and then the mode switching unit 1f is operated. Switch to "Setting mode". When the processing of the flowchart of FIG. 8 is executed in this state, it is determined that the “setting mode” is set in step S13, and the value stored in the temporary register in the microcomputer 13 is transferred to the off-timing register 1e. Is written into the off-timing register 1e (step S16). Then, the microcomputer 13 generates a phase control signal at an off timing corresponding to the off setting time Toff stored in the off timing register 1e while dimming to the target luminance level stored in the target luminance register 1c (step S15). That is, in the “setting mode”, it is possible to set an off timing at which a dimming problem does not occur by rotating the dimming knob 21 while observing the actual dimming condition. The positions 23a to 23c of the operation knob 21 in this “setting mode” correspond to the maximum value T1 to the minimum value T2 of the off setting time, as shown in FIG.

  In this way, the OFF setting time Toff is set to be changeable so that the OFF timing of the phase control signal is before the zero cross point of the current flowing through the triac Q1, so that the phase-advanced current variation due to component variations and the site-specific power supply Even if there is a difference in environment, dimming problems can be prevented.

  Then, after setting the off setting time Toff in the “setting mode” and switching to the “determined mode”, the target luminance level data stored in the target luminance register 1c and the off timing data stored in the off timing register 1e are referred to. Then, dimming control is performed.

  Further, no current transformer is required to control the ignition phase angle of the triac Q1, and it can be configured in a small size and at a low cost.

  The minimum luminance register 1d according to the first embodiment and the off timing register 1e according to the second embodiment may be provided so that both the minimum luminance and the off timing can be set in the “setting mode”.

1 is a block diagram illustrating a schematic configuration of a dimmer according to Embodiment 1. FIG. It is a circuit diagram which shows a circuit structure same as the above. It is a front view which shows the external appearance same as the above. It is a flowchart figure which shows a phase control process same as the above. It is a figure which shows the setting of the target luminance level same as the above. It is a figure which shows the setting of the minimum luminance level same as the above. FIG. 6 is a circuit diagram illustrating a part of the circuit configuration of the dimmer of the second embodiment. It is a flowchart figure which shows a phase control process same as the above. (A) is an output voltage, (b) is a waveform diagram showing a phase control signal. It is a circuit diagram which shows the circuit structure of the conventional dimmer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dimmer 1a Control circuit 1b Zero cross detection circuit 1c Target brightness register 1d Minimum brightness register 1f Mode switching part Q1 Triac DT Electronic down transformer La Lighting load AC AC power supply

Claims (5)

A bi-directional switching element having a self-holding function is provided, and the bi-directional switching element is connected in series with an AC power source and a lighting device that rectifies the input and converts it to high-frequency power and supplies it to a lighting load. In the dimmer that configures the circuit and makes the effective power to the lighting load variable by making the firing phase angle of the bidirectional switching element variable,
Zero-cross detection means for detecting the zero-cross point of the input voltage from the AC power supply;
Control means for generating a driving voltage for turning on the bidirectional switching element in synchronization with the cycle of the AC power supply based on the detection result of the zero-crossing detecting means, and performing DC trigger type phase control that continues to provide the driving voltage during the ON period; ,
A first register storing data of a target luminance level of the lighting load;
A second register storing data of the minimum luminance level of the lighting load;
Mode switching means for switching between a fixed mode and a setting mode;
With
The control means writes the data of the minimum luminance level to the second register in the setting mode, and controls the lighting load to be the target luminance level in the determination mode, and the target luminance level is equal to or lower than the minimum luminance level. Is a dimmer characterized by turning off the lighting load. A bi-directional switching element having a self-holding function is provided, and the bi-directional switching element is connected in series with an AC power source and a lighting device that rectifies the input and converts it to high-frequency power and supplies it to a lighting load. In the dimmer that configures the circuit and makes the effective power to the lighting load variable by making the firing phase angle of the bidirectional switching element variable,
Zero-cross detection means for detecting the zero-cross point of the input voltage from the AC power supply;
Control means for generating a driving voltage for turning on the bidirectional switching element in synchronization with the cycle of the AC power supply based on the detection result of the zero-crossing detecting means, and performing DC trigger type phase control that continues to provide the driving voltage during the ON period; ,
A first register storing data of a target luminance level of the lighting load;
A second register storing driving voltage off timing data for the zero cross point;
Mode switching means for switching between a fixed mode and a setting mode;
With
The control means writes drive voltage off timing data to the second register in the setting mode, and dimming control of the illumination load so that the drive voltage is turned off at the off timing and at the target luminance level in the definite mode. A dimmer characterized by The operation means for setting data of a target luminance level to be stored in the first register in a confirmation mode and setting data of a minimum luminance level to be stored in the second register in a setting mode. The dimmer according to 1. An operation means is provided for setting data of a target luminance level stored in the first register in the confirmation mode and setting off-time data of the drive voltage stored in the second register in the setting mode. The dimmer according to claim 2. A bi-directional switching element having a self-holding function is provided, and the bi-directional switching element is connected in series with an AC power source and a lighting device that rectifies the input and converts it to high-frequency power and supplies it to a lighting load. In the dimmer that configures the circuit and makes the effective power to the lighting load variable by making the firing phase angle of the bidirectional switching element variable,
Zero-cross detection means for detecting the zero-cross point of the input voltage from the AC power supply;
Control means for generating a driving voltage for turning on the bidirectional switching element in synchronization with the cycle of the AC power supply based on the detection result of the zero-crossing detecting means, and performing DC trigger type phase control that continues to provide the driving voltage during the ON period; ,
A first register storing data of a target luminance level of the lighting load;
A second register storing data of the minimum luminance level of the lighting load;
A third register storing drive voltage off timing data for the zero cross point;
Mode switching means for switching between a fixed mode and a setting mode;
With
The control means writes the minimum luminance level data to the second register in the setting mode, writes the driving voltage off timing data to the third register, and turns off the driving voltage at the off timing in the definite mode. A dimmer characterized in that dimming control is performed on the lighting load so that the target luminance level is reached, and the lighting load is turned off when the target luminance level is equal to or lower than the minimum luminance level.

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