JP2022079411A - Dimming circuit and dimming method - Google Patents

Abstract

To provide a dimming circuit and a dimming method, capable of expanding a dimming range and deepening a dimming depth.SOLUTION: A dimming circuit includes: a light emitting unit; a power unit configured to supply a first current to the light emitting unit; a constant current compensation unit configured to be electrically connected between an auxiliary power supply and a second end of the light emitting unit and supply a compensation current; a sampling unit configured to be electrically connected between the second end of the light emitting unit and a second output end of the power unit, and output and reflect a sampling signal of a second current flowing through the sampling unit; and a control unit configured to determine a first dimming reference signal and a second dimming reference signal based on a dimmer signal, control such that the power unit adjusts the second current based on the first dimming reference signal and the sampling signal and control such that the constant current compensation unit adjusts the compensation current based on the second dimming reference signal, thereby adjusting the first current flowing through the light emitting unit based on the second current and the compensation current.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a lighting technology field, and specifically to a dimming circuit and a dimming method.

With the seriousness of awareness of energy saving and environmental protection, there is a tendency to develop lighting technology having the advantages of energy saving, for example, LED (Light Emitting Diode) technology. The unique characteristics of the LED itself are suitable for dimming, which can make home lighting more comfortable and office lighting more energy saving compared to conventional light sources. In the dimmed state, the light efficiency of the system is significantly improved, and the life of the light source and the circuit part is greatly extended.

In addition, since light gives a special visual effect to a person and plays an excellent role in adjusting a person's biological rhythm, more lighting products provide a better life quality experience to the user centering on comfortable scene lighting and experience. Bring.

Conventionally, dimming is performed by analog dimming technology, and the dimming range is limited due to the influence of the range of the dimming reference signal and the accuracy of the operational amplifier.
The matters described in Background Techniques have been created to enhance understanding of the background of this Disclosure and constitute prior art known to those of ordinary skill in the art to which this Disclosure belongs. Can include items that are not.

The present disclosure provides a dimming circuit and a dimming method capable of extending a dimming range and increasing a dimming depth.

Other features and advantages of the present disclosure will become apparent from the detailed description below or will be learned in part by the implementation of the present disclosure.

The embodiments of the present disclosure provide a dimming circuit, the light emitting unit including the first end and the second end, and the first output end and the second output end are the first end of the light emitting unit. And the second end are electrically coupled to each other to supply the first current to the light emitting unit, and the auxiliary power supply is electrically connected to the second end of the light emitting unit to compensate. A sampling signal of the second current that is electrically connected and flows between the constant current compensation unit that supplies current and the second end of the light emitting unit and the second output end of the power unit is output and reflected. The first dimming reference signal and the second dimming reference signal are output based on the input dimmer signal and the first dimming reference signal and the sampling signal. By controlling the power unit to adjust the second current and controlling the constant current compensation unit to adjust the compensation current based on the second dimming reference signal, the second It includes a control unit that adjusts the first current flowing through the light emitting unit based on the current and the compensation current.

In some embodiments of the present disclosure, the control unit receives the dimmer signal, and if the dimmer signal is smaller than a preset threshold, the first dimming reference signal and the dimming reference signal. Based on the sampling signal, the power unit adjusts the second current and controls it to be fixed to a preset current value, and the constant current compensation unit adjusts the second current to be fixed to a preset current value, and the constant current compensation unit is based on the second dimming reference signal. By controlling to generate the compensating current, the first current is adjusted based on the second current and the compensating current.

In some embodiments of the present disclosure, when the dimmer signal is smaller than the preset threshold value, the first dimming reference signal is fixed to the preset reference value.

In some embodiments of the present disclosure, when the dimmer signal is greater than or equal to the preset threshold, the control unit does not operate the constant current compensation unit so that the compensation current becomes zero. By controlling to, the first current is equal to the second current, and the first current is adjusted based on the first dimming reference signal.

In some embodiments of the present disclosure, the constant current compensation unit comprises a first operational amplifier, a first resistor and a power element, the first end of the first resistor being the first of the power elements. Electrically connected to the ends, the second end of the first resistor is electrically connected to the second end of the op amp, and the second end of the op amp is electrically connected to the auxiliary power supply. Connected, the output end of the first operational amplifier is electrically connected to the control end of the power element, the first input end of the first operational amplifier is electrically connected to the control unit, and the first. Upon receiving the dimming reference signal of 2, the second input end of the first operational amplifier is electrically connected to the first end of the first resistor.

In some embodiments of the present disclosure, the voltage of the auxiliary power supply is smaller than the output voltage of the power unit.

In some embodiments of the present disclosure, the sampling unit comprises a sampling resistor, which is electrically connected between a second end of the light emitting unit and a second output end of the power unit. To.

In some embodiments of the present disclosure, the resistance value of the first resistor is greater than the resistance value of the sampling resistor.

In some embodiments of the present disclosure, the dimming circuit further comprises a second operational amplifier, the output end of the second operational amplifier is electrically coupled to the power unit, and the first of the second operational amplifier. The input end of the first dimming reference signal is received, and the second input end of the second operational amplifier receives the sampling signal of the sampling unit.

In some embodiments of the present disclosure, the dimming circuit further comprises a drive unit, the drive unit being electrically connected between an output end of the control unit and the power unit, the power unit. It is driven so as to adjust the first current.

In some embodiments of the present disclosure, when the dimmer signal is smaller than the preset threshold, the control unit draws the second current as the dimmer signal gradually decreases. By controlling the current value to be maintained at a preset value and further controlling the compensation current to gradually increase, the first current is controlled to gradually decrease.

An embodiment of the present disclosure provides a dimming method, receiving a dimmer signal, sampling a second current flowing through a sampling unit, and first adjusting based on the dimmer signal. The optical reference signal and the second dimming reference signal are determined, and when the dimmer signal is smaller than a preset threshold value, the first dimming reference signal is transmitted to the control unit, and the first dimming reference signal is transmitted. Based on the dimming reference signal of 1, the power unit adjusts the second current and controls it to be fixed to a preset current value, and the constant current compensation unit controls to generate a compensation current. 2. The dimming reference signal of 2 is transmitted to the constant current compensation unit, and the second current and the first current flowing through the light emitting unit are adjusted based on the second current and the compensation current.

In some embodiments of the present disclosure, when the dimmer signal is equal to or greater than the preset threshold value, the constant current compensation unit is controlled so as not to operate so that the compensation current becomes 0. The first current is equal to the second current, and the first current is adjusted based on the first dimming reference signal.

In some embodiments of the present disclosure, when the dimmer signal is smaller than the preset threshold, the second current is referred to as the preset current as the dimmer signal gradually decreases. By controlling the value to be maintained and further controlling the compensation current so as to gradually increase, the first current is controlled to gradually decrease.

In some embodiments of the present disclosure, the constant current compensation unit comprises a first operational amplifier, a first resistor and a power element, the first end of the first resistor being the first of the power elements. Electrically connected to the ends, the second end of the first resistor is electrically connected to the second end of the op amp, and the second end of the op amp is electrically connected to the auxiliary power supply. The output end of the first operational amplifier is electrically connected to the control end of the power element, and the first input end of the first operational amplifier is electrically connected to the control unit. The dimming reference signal is received, and the second input end of the first operational amplifier is electrically connected to the first end of the first resistor.

In some embodiments of the present disclosure, the voltage of the auxiliary power supply is smaller than the output voltage of the power unit.

In some embodiments of the present disclosure, the sampling unit is configured as a sampling resistor, and the resistance value of the first resistor is larger than the resistance value of the sampling resistor.

In the dimming circuit according to the embodiment of the present disclosure, the control unit determines the first dimming reference signal and the second dimming reference signal based on the input dimmer signal, and determines the first dimming reference signal. The power unit controls to adjust the second current flowing through the sampling unit based on the reference signal and the sampling signal, and the constant current compensation unit controls to adjust the compensation current based on the second dimming reference signal. However, by adjusting the first current flowing through the light emitting unit based on the second current and the compensation current, the first current flowing through the light emitting unit can be reduced to a lower dimming range.

This dimming circuit is low cost and easy to realize, has a small loss, and the constant current compensation unit adjusts the compensation current to adjust the first current flowing through the light emitting unit, thereby achieving the accuracy of the operational amplifier. And dimming that is not affected by the offset voltage is possible.

The above contents and the following detailed explanations are merely examples, and do not limit the present disclosure.
Still other objectives, features and advantages of the present disclosure will be clarified by more detailed description based on the examples of the present disclosure and the accompanying drawings described below.

It is a schematic diagram of a dimming circuit in a related technique. It is a schematic diagram of a dimming curve in a related technique. It is a schematic diagram of the dimming circuit in the Example of this disclosure. It is a schematic diagram of the change of the dimmer signal, the first dimming reference signal and the second dimming reference signal in the embodiment of this disclosure. It is a schematic diagram of the change of the 1st current I _b , the 2nd current I _a , and the compensation current I _c in the Example of this disclosure. It is a schematic diagram of the dimming circuit in the Example of this disclosure. It is a schematic diagram of the constant current compensation unit in the Example of this disclosure. It is a flowchart of the dimming method in the Example of this disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the embodiments of the present disclosure can be embodied in various forms, and are not limited to the examples described here. Rather, these embodiments are provided so that the present disclosure is more complete and complete, and that the concepts of exemplary embodiments are fully communicated to those of skill in the art. The drawings are merely schematics of the present disclosure and are not necessarily drawn to scale. In the drawings, the same or corresponding parts are designated by the same reference numerals and the description thereof will be omitted.

It should be noted that the described features, structures, or properties may be incorporated into one or more embodiments in any suitable manner. In the following description, a number of specific details are provided to provide a complete understanding of the embodiments of the present disclosure. However, one of ordinary skill in the art may implement the technical solutions of the present disclosure without one or more of the particular details, or other methods, components, devices, steps, etc. may be employed. You will recognize that. In other examples, well-known structures, methods, devices, implementations, or operations for avoiding concerns that obscure aspects of the present disclosure are not shown or omitted in detail.

The terms "first" and "second" are for illustration purposes only and should not be understood or implied as indicating or implying relative importance, or technically indicated. It should not be understood as an indication of the number of features. Thus, a feature defined as "first", "second" may include one or more of its features, either explicitly or implicitly.

FIG. 1 shows a schematic diagram of a dimming circuit in a related technique.

FIG. 2 shows a schematic diagram of a dimming curve in a related technique.

As shown in FIGS. 1 and 2, in a related technique, the output ends of a DC / DC converter are electrically coupled to LEDs + and LEDs across the LED, and the DC / DC converter supplies current to the LEDs. A sampling resistor Rsense is connected in series to the current circuit, the current _Ia flowing through the LED is sampled by the sampling resistor Rsense, the current Ia is converted into _a sampling voltage signal Vsense, and the voltage signal Vsense and the dimming reference signal are used as an operational capacitor. Upon input, the operational amplifier outputs a control signal to the drive unit, and the drive unit drives the DC / DC converter to adjust the current _Ia flowing through the LED.

However, if the dimming depth is reduced below a certain threshold TH, the value of the current _Ia should also be reduced below a certain threshold I_TH. However, in this case, the values of the dimming reference signal and the sampling voltage signal become as small as the Offset voltage level of the operational amplifier, and the current _Ia flowing through the LED is affected by the accuracy of the operational amplifier and the inherent Offset voltage. Adjustment accuracy becomes inaccurate.

The dimming depth indicates a dimming ratio, and may be a ratio between the brightness adjustable by the LED and the brightest brightness, or may be a ratio between the current flowing through the LED and the current at full load. For example, when the dimming depth threshold TH is 1%, I_TH is 1% of the total load current, and in this case, both the dimming reference signal and the sampling voltage signal Vsense are 1% of the full load state. At this time, if deeper dimming depth needs to be achieved more accurately, i.e., darker LED brightness needs to be achieved, the sampling voltage signal due to op amp accuracy and inherent Offset voltage limitation. The reference value of the Vsense and the corresponding dimming reference signal can only be increased, at which time the resistance of the sampling resistor Rsense needs to be increased, which significantly increases the loss.

Here, the minimum dimming depth of a general analog-controlled dimming circuit can be limited to about 1% to 5%. Due to hardware requirements, deeper dimming depths cannot be achieved and more application scenarios and user needs cannot be met.

The embodiments of the present disclosure are based on the above-mentioned technical problems of the prior art, and provide a dimming circuit that solves at least one of the above-mentioned technical problems of the prior art. FIG. 3 schematically shows a schematic diagram of a dimming circuit according to an embodiment of the present disclosure.

As shown in FIG. 3, the dimming circuit includes a light emitting unit 101, a power unit 102, a constant current compensation unit 103, a sampling unit 104, and a control unit 105.

Here, the light emitting unit 101 includes a first end 101a and a second end 101b.

The first output end 102a and the second output end 102b of the power unit 102 are electrically coupled to the first end 101a and the second end 101b of the light emitting unit 101, respectively, and the power unit 102 is attached to the light emitting unit 101. The current _Ib of 1 is supplied.

The constant current compensation unit 103 is electrically connected between the auxiliary power supply 108 and the second end 101b of the light emitting unit 101, and the constant current compensation unit 103 supplies the compensation current _Ic .

The sampling unit 104 is electrically connected between the second end 101b of the light emitting unit 101 and the second output end 102b of the power unit 102, and the sampling unit 104 has a second current I _a flowing through the sampling unit 104. The sampling signal of is output and reflected. The sampling signal may be a voltage signal.

The control unit 105 receives the input dimmer signal, determines the first dimming reference signal V _ref1 and the second dimming reference signal V _ref2 based on the dimmer signal, and determines the first dimming reference signal V ref2. The power unit 102 controls to adjust the second current _Ia based on the dimming reference signal V _ref 1 and the sampling signal, and the constant current compensation unit 103 is based on the second dimming reference signal V _ref 2. The compensation current I _c is controlled to be adjusted, whereby the first current I _b flowing through the light emitting unit 101 is adjusted based on the second current I _a and the compensation current I _c .

In the embodiments of the present disclosure, the sum of the first current I _b and the compensating current I _c is equal to the second current I _a .

FIG. 4 shows a schematic diagram of changes in the dimmer signal, the first dimming reference signal, and the second dimming reference signal in the embodiments of the present disclosure.

FIG. 5 shows a schematic diagram of changes in the first current I _b , the second current I _a , and the compensation current I _c in the embodiments of the present disclosure.

In the embodiment of the present disclosure, as shown in FIGS. 4 and 5, when the dimmer signal is equal to or higher than the preset threshold value V_TH, the control unit 105 controls the constant current compensation unit 103 so as not to operate. For example, the second dimming reference signal V _ref 2 is controlled to be 0, and at this time, the compensation current I _c becomes 0, whereby the first current I _b becomes the second current I _a . Equally, the control unit 105 can directly adjust the first current I _b based on the first dimming reference signal V _ref 1.

As the dimming depth increases, the dimmer signal gradually decreases, the corresponding first dimming reference signal V _ref 1 also gradually decreases, and both the first current I _b and the second current I _a gradually decrease. During this period, the second dimming reference signal V _ref2 is held at 0, and the compensation current _Ic is also held at 0.

Further, when the dimmer signal is smaller than the preset threshold value V_TH, the control unit 105 controls the first dimming reference signal V _ref1 based on the dimmer signal to set a preset reference value. It is fixed to V _{ref1_TH} , and the second dimming reference signal V _ref2 is controlled to be gradually increased, and the control unit 105 is based on the fixed first dimming reference signal V _ref1 and the sampling signal. The power unit 102 controls to maintain the second current I _a at a preset current value I _{a_TH} , and the constant current compensation unit 103 compensates the current I based on the second dimming reference signal V _ref 2. It is controlled to generate _c , whereby the first current I _b flowing through the light emitting unit 101 is controlled based on the second current I _a and the compensation current I _c .

In the embodiments of the present disclosure, as shown in FIGS. 4 and 5, when the dimmer signal is smaller than the preset threshold V_TH, the control unit becomes second as the dimmer signal gradually decreases. The current I _a is controlled to be held at the preset current value I _{a_TH} , and the compensation current I _c is controlled to gradually increase, whereby the first current I _b gradually decreases. To control. When the sum of the first current I _b and the compensation current I _c is equal to the second current I _a , that is, I _{a_TH} = I _b + I _c , so that the second current I _a is kept constant. As the compensation current I _c gradually increases and the first current I _b gradually decreases, the light emitting unit 101 can reach a deeper dimming depth.

In the embodiments of the present disclosure, the voltage of the auxiliary power supply 108 may be much smaller than the output voltage of the power unit, in which case the power loss of the constant current compensation unit is negligibly small.

The above-mentioned preset threshold value V_TH, preset reference value V _{ref1_TH} , and preset current value I _{a_TH} may each be set according to actual requirements, and the present disclosure is limited thereto. Not done. For example, in some embodiments, the preset threshold value V_TH may be set to a value of a dimmer signal corresponding to a dimming depth range of 1% to 10%, and the present disclosure is limited thereto. Not done.

In the dimming circuit according to the embodiment of the present disclosure, the control unit determines the first dimming reference signal and the second dimming reference signal based on the input dimmer signal, and determines the first dimming reference signal. The power unit controls to adjust the second current flowing through the sampling unit based on the signal and the sampling signal, and the constant current compensation unit controls to adjust the compensation current based on the second dimming reference signal. By adjusting the first current flowing through the light emitting unit based on the second current and the compensation current, the first current flowing through the light emitting unit can be reduced to a deeper dimming range. In addition, this dimming circuit is low cost and easy to realize, has a small loss, and the constant current compensation unit adjusts the compensation current to adjust the first current flowing through the light emitting unit, so that the accuracy of the operational amplifier is high. And dimming that is not affected by the offset voltage is possible.

In the embodiments of the present disclosure, the light emitting unit 101 may be an LED or another light emitting element, and the power unit 102 may be a DC / DC converter such as a Flyback, an LLC, a Boost, or a Buck. The power unit 102 converts the input power supply voltage into a current required for the light emitting unit 101 and a voltage signal required for the corresponding light emitting unit 101, and the sampling unit 104 is a sampling resistor. Is included, and is electrically connected between the second end 101b of the light emitting unit 101 and the second output end 102b of the power unit 102. The control unit 105 may be an MCU (Micro controller Unit) or another processor.

In the embodiments of the present disclosure, the dimming circuit can further include a second operational amplifier 106 and a drive unit 107. Here, the second operational amplifier 106 may be integrated in the control unit 105, and the present disclosure is not limited to this.

Hereinafter, an example will be described in which the light emitting unit is an LED, the power unit is a DC / DC converter, the sampling unit is a sampling resistor, and the dimming circuit includes a second operational amplifier and a drive unit. Not limited.

FIG. 6 shows a schematic diagram of the dimming circuit in the embodiment of the present disclosure.

As shown in FIG. 6, the dimming circuit includes an LED, a DC / DC converter 1021, a constant current compensation unit 103, a sampling resistor Rsense, and a control unit 105. Here, the LED includes a first end LED + and a second end LED-.

The first output end 1021a and the second output end 1021b of the DC / DC converter 1021 are electrically coupled to the first end LED + and the second end LED-of the LED, respectively, and the DC / DC converter 1021 becomes A first current _Ib is supplied to the LED.

The sampling resistance Rsense is electrically connected between the second end LED of the LED and the second output end 1021b of the DC / DC converter, and the sampling signal of the second current _Ia flowing through the sampling resistance Rsense is transmitted. Output and reflect. The sampling signal may be a voltage signal, or the sampling signal may be the product of the resistance value of the sampling resistance Rsense and the second current _Ia .

The constant current compensation unit 103 has its input end electrically connected to the auxiliary power supply 108 and its output end electrically connected to the second end LED of the LED-to supply the compensation current _Ic .

The control unit 105 receives the dimmer signal, determines the first dimming reference signal V _ref1 and the second dimming reference signal V _ref2 based on the dimmer signal, and determines the first dimming reference signal V ref2. The DC / DC converter 1021 controls to adjust the second current _Ia based on the signal V _ref1 and the sampling signal, and the constant current compensation unit 105 is based on the second dimming reference signal V _ref2 . By controlling the compensation current I _c to be adjusted, the first current I _b flowing through the LDE is adjusted based on the second current I _a and the compensation current _IC .

The output end 106c of the second operational amplifier 106 is electrically coupled to the drive unit 107, the first input end 106a of the second operational amplifier receives the first dimming reference signal _Vref1 and the second operational amplifier receives the first dimming reference signal Vref1. The second input terminal 106b receives the sampling signal of the sampling unit, and the second operational amplifier 106 controls the DC / DC converter 1021 based on the first dimming reference signal V _ref1 and the sampling signal to control the second The current I _a can be adjusted.

The drive unit 107 is electrically connected between the output terminal 106c of the second operational amplifier 106 and the DC / DC converter 1021, and is driven so that the DC / DC converter 1021 outputs the first current _Ib . do.

FIG. 7 shows a schematic diagram of the constant current compensation unit in the embodiment of the present disclosure.

As shown in FIG. 7, the inside of the dotted line frame is an embodiment of the constant current compensation unit in the present disclosure, and the constant current compensation unit includes a first operational amplifier 1033, a first resistor 1031, and a power element 1032.

Here, the first end 1031a of the first resistor 1031 is electrically connected to the first end 1032a of the power element 1032, and the second end 1031b of the first resistor 1031 is the second end 1031b of the light emitting unit 101. Electrically connected to the end 101b, the second end 1032b of the power element 1032 is electrically connected to the auxiliary power supply 108, and the output end 1033c of the first optotype 1033 is electrically connected to the control end 1032c of the power element 1032. Connected, the first input end 1033a of the first optotype 1033 is electrically connected to the control unit 105 to receive the second dimming reference signal V _ref2 and the second input end of the first optotype 1033. 1033b is electrically connected to the first end 1031a of the first resistor 1031.

In the embodiments of the present disclosure, the auxiliary power source 108 is a low voltage source, the negative end of which is electrically connected to the sampling resistor Rsense and is connected to the same reference ground. Vr1 is a detection voltage signal acquired based on the current flowing through the first resistance 1031 and the sampling resistance Rsense, and Vr1 = I _c * R1 + I _a * Rsense, where R1 is the first resistance 1031. Indicates the resistance value.

In the embodiment of the present disclosure, when the dimmer signal is equal to or higher than the preset threshold value V_TH, the control unit 105 controls so that the second dimming reference signal V _ref2 becomes 0 to compensate for constant current. The unit 105 does not operate, the compensation current I _c becomes 0, and the first current I _b is controlled to be equal to the second current I _a . At this time, the control unit 105 outputs the first dimming reference signal V _ref1 based on the dimming signal, and the second operational amplifier 106 DC / DC based on the first dimming reference signal V _ref1 and the sampling signal. The converter 1021 controls to adjust the second current _Ia .

When the dimmer signal is smaller than the preset threshold value V_TH, the control unit 105 adjusts the first dimming reference signal V _ref1 to control it so as to be fixed to the preset reference value V _{ref1_TH} , and the first When the dimming reference signal V ref 1 of 1 is fixed, the second current I _a is stabilized at the _{preset current value I a_TH .} On the other hand, the control unit 105 outputs a non-zero second dimming reference signal V _ref2 based on the dimmer signal, and the constant current compensation unit 105 compensates current I _c based on the second dimming reference signal V _ref2 . Is generated to adjust the first current I _b . Specifically, the second current I _a is constant, the I _a * Signal is constant, and the control first operational capacitor 1033 is controlled to operate in the linear amplification region, whereby Vr1 and the second adjustment are performed. The optical reference signal V _ref2 is equal to, and in this way, the magnitude of the compensation current _Ic can be controlled by controlling the second dimming reference signal V _ref2 , for example, the dimmer signal gradually changes. When it becomes smaller, the control unit 105 controls so that the second dimming reference signal V _ref2 gradually increases, and the compensation current _Ic also gradually increases. When the second current I _a is constant, the compensation current I _c can be gradually increased and the first current I _b can be gradually reduced to a deeper dimming depth.

In the embodiments of the present disclosure, the voltage of the auxiliary power supply 108 may be considerably smaller than the output voltage of the power unit 102. In some embodiments, the output voltage may be generally tens to hundreds of volts and the voltage of the auxiliary power supply may be generally several volts. Therefore, the loss is so small that it can be ignored, and the light load efficiency can be maintained high.

In the embodiment of the present disclosure, the resistance value R1 of the first resistor 1031 may be sufficiently larger than the resistance value of the sampling resistor Rsense. The value of Ic * R1 is much larger than the value of the sampling signal of the sampling resistor Rsense, and the magnitude of the control compensation current _Ic can be controlled more accurately.

FIG. 8 shows a flowchart of the dimming method in the embodiment of the present disclosure.

As shown in FIG. 8, the dimming method according to the embodiment of the present disclosure includes steps S802 to S808.

In step S802, the dimmer signal is received.

For example, the control unit 105 receives the dimmer signal, and a schematic diagram of the change in the dimmer signal is shown in FIG. In some embodiments, the dimmer signal is typically from a command or signal in the desired dimming range of the LED emitted by the dimming controller, where the dimming controller is, for example, 0-10V dimming. A vessel or a DALI® controller, etc.

In step S804, the second current flowing through the sampling unit is sampled.

In the embodiment of the present disclosure, the sampling unit may be configured as a sampling resistor. The sampling unit may output and reflect the sampling signal of the second current flowing through the sampling unit, and the sampling signal may be a voltage signal.

In step S806, the first dimming reference signal and the second dimming reference signal are determined based on the dimmer signal.

For example, when the dimmer signal is equal to or higher than the preset threshold value V_TH, it is determined that the first dimming reference signal V _ref1 is reduced as the dimmer signal decreases, and the second dimming reference signal V _ref2 is determined. Is determined to be 0, and if the dimmer signal is smaller than the preset threshold V_TH, it is determined that the first dimming reference signal V _ref1 is fixed to the preset reference value V _ref1 _ _TH . The second dimming reference signal V _ref2 is increased as the dimmer signal decreases.

In step S808, when the dimmer signal is smaller than the preset threshold value, the first dimming reference signal is transmitted to the control unit, and the power unit receives the second current based on the first dimming reference signal. Is adjusted so as to be fixed to a preset current value, and a second dimming reference signal is transmitted to the constant current compensation unit, and the second dimming reference signal is compensated by the constant current compensation unit. The current is controlled to be generated, and the first current flowing through the light emitting unit is adjusted based on the second current and the compensation current.

For example, when the dimmer signal is smaller than the preset threshold value V_TH, the first dimming reference signal V _ref1 is fixed to the preset reference value V _ref1 _ _TH and is set to the first reference signal V _ref1 . Based on this, the power unit adjusts the second current I _a to fix it to the preset current value I _{a_TH} , and increases the second dimming reference signal V ref 2 as the dimmer signal decreases, so that the second dimming reference signal V _ref 2 is increased. The constant current compensation unit is controlled to generate the compensation current _Ic based on the dimming reference signal V _ref 1, and the first current I _b flowing through the light emitting unit based on the second current I _a and the compensation current I _c . To adjust. For example, as the dimmer signal gradually decreases, the control second current I _a is held at a preset current value, and the control compensation current I _c gradually increases, so that the first current Control so that I _b gradually decreases.

In the embodiment of the present disclosure, when the dimmer signal is equal to or higher than the preset threshold value V_TH, the constant current compensation unit is controlled not to operate, and the compensation current _Ic becomes 0, so that the first current I _b is equal to the second current I _a , and the first current I _b is adjusted based on the first dimming reference signal V _ref 1.

In the present disclosure, when the dimming reaches a certain depth, the dimming range below a certain threshold is realized by the control of the constant current compensation unit, the current in the sampling resistance LED is kept constant, and the constant current compensation unit compensates. The current is gradually increased from 0, thereby reducing the LED current and reaching a deeper dimming range. Further, since the voltage of the auxiliary power supply connected to the constant current compensation unit of the present disclosure is much smaller than the output voltage of the DC / DC converter, the loss in the constant current compensation unit is also negligibly small, and the light load efficiency is reduced. Can be kept high.

It should be noted that the block diagram shown in each of the above-mentioned figures is functional and does not necessarily correspond to a physically or logically independent existence. These functional entities may be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontroller devices.

The embodiments of the present disclosure have been specifically shown and described above. It should be understood that the present disclosure is not limited to the detailed structure, configuration, or method of implementation described herein. Rather, the present disclosure is intended to include various modifications and equivalent configurations contained within the spirit and scope of the appended claims.

Claims (15)

A light emitting unit including a first end and a second end,
A power unit in which a first output end and a second output end are electrically coupled to the first end and the second end of the light emitting unit, respectively, to supply a first current to the light emitting unit, and a power unit.
A constant current compensation unit that is electrically connected between the auxiliary power supply and the second end of the light emitting unit to supply a compensation current, and a constant current compensation unit.
A sampling unit that is electrically connected between the second end of the light emitting unit and the second output end of the power unit and outputs and reflects a sampling signal of a flowing second current.
The first dimming reference signal and the second dimming reference signal are determined based on the input dimmer signal, and the power unit is the first based on the first dimming reference signal and the sampling signal. By controlling so as to adjust the current of 2, and controlling the constant current compensating unit to adjust the compensating current based on the second dimming reference signal, the second current and the compensating current are adjusted. A control unit that adjusts the first current flowing through the light emitting unit based on the above.
A dimming circuit characterized by that. When the control unit receives the dimmer signal and the dimmer signal is smaller than a preset threshold value, the power unit causes the power unit based on the first dimming reference signal and the sampling signal. The second current is adjusted and controlled to be fixed to a preset current value, and the constant current compensation unit is controlled to generate the compensation current based on the second dimming reference signal. The first current is adjusted based on the second current and the compensation current.
The dimming circuit according to claim 1. When the dimmer signal is smaller than the preset threshold value, the first dimming reference signal is fixed to the preset reference value.
The dimming circuit according to claim 2. When the dimmer signal is equal to or higher than the preset threshold value, the control unit controls the constant current compensation unit so that the compensation current becomes 0 so that the constant current compensation unit does not operate. The current is equal to the second current and the first current is adjusted based on the first dimming reference signal.
The dimming circuit according to claim 2. The constant current compensation unit includes a first operational amplifier, a first resistor and a power element.
The first end of the first resistance is electrically connected to the first end of the power device and the second end of the first resistance is electrically connected to the second end of the light emitting unit. Being done
The second end of the power element is electrically connected to the auxiliary power source.
The output end of the first operational amplifier is electrically connected to the control end of the power element, the first input end of the first operational amplifier is electrically connected to the control unit, and the second adjustment is performed. Upon receiving the optical reference signal, the second input end of the first operational amplifier is electrically connected to the first end of the first resistor.
The dimming circuit according to claim 2. The voltage of the auxiliary power supply is smaller than the output voltage of the power unit.
The dimming circuit according to any one of claims 1 to 5, wherein the dimming circuit is characterized. The sampling unit includes a sampling resistor, which is electrically connected between a second end of the light emitting unit and a second output end of the power unit.
The resistance value of the first resistor is larger than the resistance value of the sampling resistor.
The dimming circuit according to claim 5. The dimming circuit further includes a second operational amplifier, the output end of the second operational amplifier is electrically coupled to the power unit, and the first input end of the second operational amplifier is the first dimming. The reference signal is received, and the second input end of the second operational amplifier receives the sampling signal of the sampling unit.
The dimming circuit according to claim 2. When the dimmer signal is smaller than the preset threshold, the control unit keeps the second current at the preset current value as the dimmer signal gradually decreases. And further, by controlling so that the compensation current gradually increases, the first current is controlled to gradually decrease.
The dimming circuit according to claim 2. Receiving a dimmer signal and
Sampling the second current flowing through the sampling unit,
Determining the first dimming reference signal and the second dimming reference signal based on the dimmer signal, and
When the dimmer signal is smaller than a preset threshold value, the first dimming reference signal is transmitted to the control unit, and the power unit receives the second current based on the first dimming reference signal. Is adjusted so as to be fixed to a preset current value, and a second dimming reference signal for controlling the constant current compensation unit to generate a compensation current is transmitted to the constant current compensation unit. Including adjusting the first current flowing through the light emitting unit based on the second current and the compensation current.
A dimming method characterized by that. When the dimmer signal is equal to or higher than the preset threshold value, the constant current compensation unit is controlled so as not to operate so that the compensation current becomes 0, so that the first current becomes the second current. Is equal to the current of, and the first current is adjusted based on the first dimming reference signal.
The dimming method according to claim 10, wherein the dimming method is characterized. When the dimmer signal is smaller than the preset threshold value, the second current is controlled to be held at the preset current value as the dimmer signal gradually decreases, and further. By controlling the compensation current to gradually increase, the first current is controlled to gradually decrease.
The dimming method according to claim 10, wherein the dimming method is characterized. The constant current compensation unit includes a first operational amplifier, a first resistor and a power element.
The first end of the first resistance is electrically connected to the first end of the power device and the second end of the first resistance is electrically connected to the second end of the light emitting unit. Being done
The second end of the power element is electrically connected to the auxiliary power source.
The output end of the first operational amplifier is electrically connected to the control end of the power element, the first input end of the first operational amplifier is electrically connected to the control unit, and the second adjustment is performed. Upon receiving the optical reference signal, the second input end of the first operational amplifier is electrically connected to the first end of the first resistor.
The dimming method according to claim 10, wherein the dimming method is characterized. The voltage of the auxiliary power supply is smaller than the output voltage of the power unit.
The dimming method according to claim 13. The sampling unit is configured as a sampling resistor, and the resistance value of the first resistor is larger than the resistance value of the sampling resistor.
The dimming method according to claim 13.

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