CN212649755U

CN212649755U - LED dimming drive circuit and dimming system

Info

Publication number: CN212649755U
Application number: CN202021376620.2U
Authority: CN
Inventors: 叶美盼
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2020-07-14
Filing date: 2020-07-14
Publication date: 2021-03-02
Anticipated expiration: 2030-07-14

Abstract

The utility model provides a LED drive circuit and dimming system of adjusting luminance, wherein LED drive circuit that adjusts luminance includes: the device comprises a reference generation module, a reference selection module and a driving module. The reference generation module can simultaneously generate a dimming reference signal and a reference compensation maintaining signal, and the reference compensation maintaining signal compensates a difference value between an actual reference signal and an expected reference signal caused by shutdown delay, so that the problem of brightness overshoot caused by the shutdown action delay can be solved, and the dimming experience of a user is improved.

Description

LED dimming drive circuit and dimming system

Technical Field

The utility model relates to a power electronic technology field, in particular to LED drive circuit and the dimming system of adjusting luminance adjusts luminance.

Background

With the increasing demand for energy saving, lamps with dimming function have appeared. The lamp can change the brightness, the color and the like of the light so as to achieve certain comfort level and meet the requirement of people on energy conservation. The lamp with the dimming function comprises a bulb lamp, a down lamp, a T-tube lamp, a panel lamp and the like.

However, in general, a home and a company control the on and off of the lamp through a wall power switch, and a dimmer is not reserved on a wall, so that the dimming can be performed only through the switch. The existing dimming method realizes dimming by detecting the on-off of a power switch through a control module, but the brightness is not the brightness really desired by a user when the power switch is turned on next time due to shutdown delay.

Therefore, the conventional LED dimming driving circuit has a problem that the dimming experience of the user is poor due to the overshoot of the brightness caused by the delay of the shutdown operation, that is, the actual brightness of the LED lamp is greater than the expected value.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a LED drive circuit and the dimming system of adjusting luminance to solve the overshoot problem of the luminance that shutdown action time delay leads to, increase user's the experience of adjusting luminance and feel.

In order to achieve the above objects and other related objects, the present invention provides a LED dimming driving circuit, including:

the reference generation module generates a dimming reference signal and a reference compensation holding signal;

the reference selection module is connected with the reference generation module and is used for selecting one of the dimming reference signal and the reference compensation and maintenance signal as a reference signal, and when the brightness of the LED lamp reaches a desired value, the reference compensation and maintenance signal is selected as the reference signal to compensate the dimming reference signal, so that the brightness of the LED lamp is maintained at the desired brightness value;

and the driving module is connected with the reference selection module, generates a control signal according to the reference signal and is used for adjusting the brightness of the LED lamp.

Optionally, in the LED dimming driving circuit, when the brightness of the LED lamp does not reach a desired brightness value, the dimming reference signal is selected as the reference signal.

Optionally, in the LED dimming driving circuit, in the same time, the variation of the dimming reference signal is greater than or equal to the variation of the reference compensation hold signal.

Optionally, in the LED dimming driving circuit, the LED dimming driving circuit further includes a detection module, which generates a detection signal according to a sampling signal representing the input voltage and a reference signal, and when the sampling signal is less than or equal to the reference signal and a duration time in the state is greater than or equal to a time threshold, a state of the detection signal output by the detection module is a first level, and otherwise, a state of the detection signal output by the detection module is a second level.

Optionally, in the LED dimming driving circuit, the reference generating module includes:

the logic signal generating module receives a detection signal, counts the detection signal to obtain a count value, generates a dimming signal and a compensation signal according to the count value, outputs the compensation signal when the count value is an even number, and controls the reference selecting module to select a reference compensation holding signal as a reference signal; and when the count value is an odd number, the logic signal generation module outputs a dimming signal and controls the reference selection module to select the dimming reference signal as the reference signal.

Optionally, in the LED dimming driving circuit, the reference generating module further includes:

the dimming reference signal generating module is connected with the logic signal generating module and used for receiving the dimming signal generated by the logic signal generating module and outputting the dimming reference signal;

and the reference compensation and holding signal generating module is connected with the logic signal generating module and used for receiving the compensation signal generated by the logic signal generating module and outputting the reference compensation and holding signal.

Optionally, in the LED dimming driving circuit, the reference selection module is respectively connected to the dimming reference signal generation module, the reference compensation holding signal generation module and the logic signal generation module, and when the count value is an even number, the logic signal generation module outputs a compensation signal and controls the reference selection module to select the reference compensation holding signal as the reference signal; and when the count value is odd, the logic signal generation module outputs a dimming signal and controls the reference selection module to select the dimming reference signal as the reference signal.

Optionally, in the LED dimming driving circuit, the brightness of the LED lamp is continuously adjusted by controlling the dimming reference signal to gradually increase or gradually decrease.

Optionally, in the LED dimming driving circuit, the logic signal generating module further generates a reset signal, and the reset signal resets the dimming reference signal and the reference compensation holding signal to initial values.

Optionally, in the LED dimming driving circuit, the set of first level and second level acts as a set, and the logic signal generating module includes:

the input end of the counter is connected with the output end of the detection module, and the counter counts the detection signals to obtain a count value;

the input end of the acquisition module is connected with the output end of the detection module and is used for acquiring the duration time of a second level in each group of actions;

the positive input end of the third comparator is connected with the output end of the acquisition module, and the negative input end of the third comparator receives the reference value, and is used for comparing the duration time of the second level of the upper group of actions with the reference value and obtaining a time comparison result;

and the storage module is connected with the third comparator and the counter and used for storing the corresponding relation between the counting value and the time comparison result and the dimming signal, the compensation signal and the reset signal.

Optionally, in the LED dimming driving circuit, when the count value is an odd number and the duration of the second level of the previous group is greater than or equal to the reference value, the logic signal generation module outputs the reset signal first, outputs the dimming signal second, and controls the dimming reference signal to start adjustment from the initial value; when the second level duration of the upper group action is less than the reference value, the logic signal generation module outputs a dimming signal and controls the dimming reference signal to continue to be adjusted on the basis of the dimming reference signal generated by the upper group action.

Optionally, in the LED dimming driving circuit, the dimming reference signal generating module includes:

the control end of the second switching tube is connected with the output end of the logic signal generation module, receives the dimming signal and is turned off or turned on according to the dimming signal;

a second current source, a second end of which is connected with the first end of the second switch tube, and a first end of which receives a third reference and generates a second current signal;

a control end of the fourth switching tube is connected with the output end of the logic signal generating module, receives a reset signal and is turned off or turned on according to the reset signal;

and a first end of the second capacitor is connected with a first end of the fourth switching tube and a second end of the second switching tube respectively, and the second current signal charges the second capacitor to generate a dimming reference signal.

Optionally, in the LED dimming driving circuit, the reference compensation hold signal generating module includes:

the control end of the third switching tube is connected with the output end of the logic signal generation module, receives the dimming signal and is turned off or turned on according to the dimming signal;

a second end of the third current source is connected with the first end of the third switching tube, and the first end of the third current source receives a third reference and generates a third current signal;

a control end of the fifth switching tube is connected with the output end of the logic signal generating module, receives a reset signal and is turned off or turned on according to the reset signal;

and a first end of a third capacitor is respectively connected with a first end of the fifth switching tube and a second end of the third switching tube, the third current signal charges the third capacitor to generate a reference compensation holding signal, and the charging speed of the second capacitor is greater than that of the third capacitor.

and the input end of the reference conversion module is connected with the first end of the second capacitor, and the output end of the reference conversion module is connected with the reference selection module, receives the dimming reference signal and converts the dimming reference signal into a reference compensation holding signal.

a control end of the second switching tube is connected with the output end of the logic signal generation module, and a first end of the second switching tube is connected with the second current source, receives a dimming signal and is turned off or turned on according to the dimming signal;

a control end of the fourth switching tube is connected with the output end of the logic signal generating module, and a second end of the fourth switching tube receives a third reference, receives a reset signal and is turned off or turned on according to the reset signal;

and the first end of the second capacitor is connected with the first end of the fourth switching tube and the second end of the second switching tube respectively, the second end of the second capacitor is grounded, and when the second switching tube is controlled to be closed by the dimming signal, the second capacitor discharges to generate the dimming reference signal.

a control end of the third switching tube is connected with the output end of the logic signal generation module, and a first end of the third switching tube is connected with the third current source, receives the dimming signal and is turned off or turned on according to the dimming signal;

a control end of the fifth switching tube is connected with the output end of the logic signal generating module, and a second end of the fifth switching tube receives a third reference, receives a reset signal and is turned off or turned on according to the reset signal;

and a first end of the third capacitor is connected with the first end of the fifth switching tube and the second end of the third switching tube respectively, a second end of the third capacitor is grounded, and when the dimming signal controls the third switching tube to be closed, the third capacitor discharges to generate the reference compensation holding signal.

the control end of the second switching tube is connected with the logic signal generating module, receives the dimming signal and is turned off or turned on according to the dimming signal;

the first pulse module is connected with the first end of the second switching tube and generates a first pulse signal;

and a first input end of the first digital-to-analog conversion module is connected with the logic signal generation module and receives the reset signal, and a second input end of the first digital-to-analog conversion module is connected with a second end of the second switching tube and generates a dimming reference signal according to the first pulse signal.

the control end of the third switching tube is connected with the logic signal generating module, receives the dimming signal and is turned off or turned on according to the dimming signal;

the second pulse module is connected with the first end of the third switching tube and generates a second pulse signal;

and a second digital-to-analog conversion module, a first input end of which is connected with the logic signal generation module and receives a reset signal, and a second input end of which is connected with a second end of the third switching tube and generates a reference compensation holding signal according to the second pulse signal.

Optionally, in the LED dimming driving circuit, a pulse frequency generated by the first pulse module is greater than a pulse frequency generated by the second pulse module.

Optionally, in the LED dimming driving circuit, when the logic signal generating module outputs a reset signal, the first digital-to-analog converting module and the second digital-to-analog converting module receive the reset signal, and reset the dimming reference signal and the reference compensation holding signal to initial values.

Optionally, in the LED dimming driving circuit, the reference selecting module includes:

a sixth switching tube, a control end of which is connected to the output end of the logic signal generating module and receives the dimming signal, a first end of which is connected to the dimming reference signal generating module and receives the dimming reference signal, and the sixth switching tube is turned off or turned on according to the dimming signal to control the output of the dimming reference signal;

and the control end of the seventh switching tube is connected with the output end of the logic signal generation module and receives the dimming signal, and the first end of the seventh switching tube is connected with the reference compensation maintaining signal and receives the compensation signal, and the seventh switching tube is turned off or closed according to the compensation signal to control the output of the reference compensation maintaining signal.

In order to achieve the above objects and other related objects, the present invention also provides a light modulation system, including:

the LED dimming driving circuit generates a control signal according to the sampling signal;

and the power conversion module is connected with the LED dimming driving circuit and controls the brightness of the LED lamp according to the control signal.

Optionally, in the dimming system, the power conversion module includes a power switch and a sampling resistor, the power switch and the sampling resistor are connected in series,

and sampling the voltage at two ends of the sampling resistor to obtain the sampling signal.

Optionally, in the dimming system, the dimming system further includes:

a power switch, a first end of which is connected with a first end of the power supply, and is used for controlling the input of the input voltage;

a rectifier bridge, a first input end of which is connected with the second end of the power switch, a second input end of which is connected with the second end of the power supply to rectify the input voltage, a first end and a second end of the LED dimming driving circuit are respectively connected with a first output end and a second output end of the rectifier bridge,

wherein the sampling signal is obtained by sampling the rectified input voltage.

Optionally, in the dimming system, the dimming system further includes:

a rectifier bridge having a first input terminal connected to the second terminal of the power switch, a second input terminal connected to the second terminal of the power switch for rectifying the input voltage, a first terminal of the LED dimming driving circuit connected to the second terminal of the power switch, and a second terminal connected to the second output terminal of the rectifier bridge,

wherein the sampling signal is obtained by sampling the input voltage.

To sum up, the utility model discloses a benchmark generation module can produce simultaneously and adjust luminance reference signal and benchmark compensation and keep the signal, and keep the actual reference signal that signal compensation shutdown delay caused and expect the difference between the reference signal through the benchmark compensation, can solve the problem of the overshoot of the luminance that shutdown action delay leads to increase user's the experience of adjusting luminance.

Drawings

FIG. 1 is a schematic block diagram of a prior art dimming system;

FIG. 2 is a waveform illustrating operation of a prior art dimming system;

fig. 3 is a schematic block diagram of a dimming system of the present invention;

fig. 4 is a schematic circuit diagram of a dimming system in the first embodiment;

FIG. 5 is a waveform diagram illustrating operation of the detection module of FIG. 4;

fig. 6 is a schematic circuit diagram of a dimming system in a second embodiment;

fig. 7 is a schematic circuit diagram of a dimming system in a third embodiment;

fig. 8 is a flowchart of a dimming method according to an embodiment of the present invention.

FIG. 9 is a partial operational waveform diagram of the control module in the first embodiment;

fig. 10 is a schematic circuit diagram of a dimming system in a fourth embodiment;

fig. 11 is a schematic circuit diagram of a dimming system in a fifth embodiment;

FIG. 12 is a partial waveform diagram of the operation of the control module in the fifth embodiment;

fig. 13 is a schematic circuit diagram of a dimming system in a sixth embodiment;

FIG. 14 is a partial waveform diagram of the operation of the control module in the sixth embodiment;

in fig. 1 to 2:

010-a power switch, 011-a rectifier bridge, 02-a control module and 03-a power conversion module;

in fig. 3 to 14:

100-a power switch module, 101-a power switch, 102-a rectifier bridge, 200-a detection module, 300-a control module, 301-a reference generation module, 302-a reference selection module, 303-a driving module and 400-a power conversion module.

Detailed Description

The LED dimming driving circuit and the dimming system provided by the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will be more apparent from the following examples. It should be noted that the drawings are in simplified form and are not to precise scale, and are provided for convenience and clarity in order to facilitate the description of the embodiments of the present invention.

Referring to fig. 1, a schematic block diagram of a prior art dimming system is shown. The block diagram includes a power switch 010, a rectifier bridge 011, a control module 02, and a power conversion module 03. The input of the ac voltage can be controlled by turning on and off the power switch 010, and the rectifier bridge 011 is used for rectifying the ac input voltage to obtain the dc bus voltage Vbus. The control module 02 detects a direct-current bus voltage Vbus obtained after rectification by the rectifier bridge 011, and judges whether the power switch 010 is closed or not so as to control the magnitude of the LED load current. The power conversion module 03 converts the dc bus voltage Vbus into a suitable dc current to supply energy to the LED load. That is, in the dimming method in the prior art, dimming is realized by detecting the on/off of the power switch through the control module.

Referring to fig. 2, a waveform diagram of the operation of a prior art dimming system is shown. It can be seen that when the power switch 010 is in the a state (the power switch 010 is closed), the output current Io of the power conversion module 03 changes with time, and when the user wants the output current Io to correspond to the reference signal at the time point t1 and operates the power switch 010 to turn off, the turn-off action (the power switch 010 is in the B state) is actually at the time point t2, and therefore, there is a delay in turning off the power switch, which causes the brightness at the next turn-on to be not the brightness really desired by the user.

In order to solve the problem of overshoot of brightness caused by shutdown delay, so as to increase the user's experience of dimming, the present invention provides a dimming system, please refer to fig. 3 to 14.

Referring to fig. 3, the dimming system includes: power switch module 100, LED dimming driving circuit and power conversion module 400. The power switch module 100 includes a power switch 101 and a rectifier bridge 102, where a first end of the power switch 101 is connected to a first end of a power supply, and input of an input voltage is controlled by on/off of the power switch 101. The first input terminal of the rectifier bridge 102 is connected to the second terminal of the power switch 101, and the second input terminal thereof is connected to the second terminal of the power supply, so as to rectify the input voltage.

The LED dimming driving circuit includes a detection module 200 and a control module 300, and the control module 300 includes a reference generation module 301, a reference selection module 302 and a driving module 303.

The detection module 200 is connected to the power switch module 100, and specifically may be: the detection module 200 is connected between the first output terminal and the second output terminal of the rectifier bridge 102, that is, the rectified input voltage is sampled to obtain the sampling signal.

Referring to fig. 4, the detection module includes: the voltage sampling circuit, the first comparator U1, the second comparator U2, the first reference REF1 (i.e. the reference signal REF1), the second reference REF2, the first switch tube Q1, the first capacitor C1 and the first current source I1.

The voltage sampling circuit is used for sampling an input voltage and comprises a first resistor R1 and a second resistor R2. A first end of the first resistor R1 is connected to a first output end of the rectifier bridge 102; the first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the second output terminal of the rectifier bridge 102 and grounded. The first resistor R1 and the second resistor R2 obtain sampling signals through voltage division.

The positive input terminal of the first comparator U1 is connected to the output terminal of the voltage sampling circuit, i.e., to the second terminal of the first resistor R1, the negative input terminal thereof receives the reference signal REF1, and the output terminal thereof is connected to the control terminal of the first switch Q1. The voltage of the positive input end of the first comparator U1 is the sampling signal, the voltage of the negative input end of the first comparator U1 is the reference signal REF1, the sampling signal of the positive input end is compared with the reference signal REF1 of the negative input end, and a corresponding intermediate signal is output at the output end according to the comparison result. The sampling signal is lower than or equal to the reference signal, the state duration is greater than or equal to a time threshold, and the intermediate signal is at a low level; the sampling signal is lower than or equal to the reference signal, the state duration is less than a time threshold, and the first intermediate signal is a square wave low level; the sampling signal is higher than the reference signal, and the first intermediate signal is at a square wave high level. The time threshold is a value set according to actual requirements, and the square wave low level and the square wave high level form a square wave signal. For example, when the power switch 101 is closed, the first comparator U1 outputs a square wave signal according to the comparison result of the sampling signal at the positive input terminal and the reference signal REF1 at the negative input terminal, and when the sampling signal is lower than the reference signal REF1, the output signal V of the first comparator U1_U1Is low level; an output signal V of the first comparator U1 when the sampled signal is higher than the reference signal REF1_U1Is high. When the power switch 101 is turned off (i.e. the sampling signal is lower than or equal to the reference signal and the state duration is greater than or equal to the time threshold), the output signal V of the first comparator U1_U1At low level, please refer to FIG. 5.

A control terminal of the first switch Q1 is connected to the output terminal of the first comparator U1, a first terminal thereof is connected to the first terminal of the first capacitor C1, and a second terminal thereof is connected to the second terminal of the first capacitor C1 and grounded. The first comparator U1 outputting a high level can close the first switch Q1, so that the first capacitor C1 discharges to 0V. The first comparator U1 outputs a low level, the first switch Q1 is turned off, so that the first capacitor C1 is charged by the first current source I1.

The first end of the first capacitor C1 is connected to the output end of the first current source I1 and the positive input end of the second comparator U2, the negative input end of the second comparator U2 receives the second reference REF2, and the first end of the first current source I1 receives the supply voltage VCC. The positive input end voltage of the second comparator U2 is the voltage V of the first capacitor C1_C1The voltage of the negative input terminal is a second reference REF2, and the second comparator U2 converts the voltage V_C1Compares with the second reference REF2 and outputs a detection signal V according to the comparison result_U2. When the voltage V of the first capacitor C1_C1When the voltage is higher than the second reference REF2, the detection signal V output by the second comparator U2_U2Is a first level, which is a high level; when the voltage V of the first capacitor C1_C1When the voltage is lower than the second reference REF2, the detection signal V output by the second comparator U2_U2Is a second level, which is a low level. Because the sampling signal is less than or equal to the reference signal and the duration time in the state is greater than or equal to the time threshold, the first capacitor C1 is continuously charged, so that the voltage V of the first capacitor C1 is enabled to be V_C1Above the second reference REF2, the second comparator U2 outputs a high level (i.e., a first level), please refer to fig. 5, the sampling signal is greater than the reference signal, the duration of the sampling signal being less than or equal to the reference signal is less than the time threshold, the sampling signal is greater than the reference signal, the first capacitor C1 is continuously discharged and charged, and the voltage V of the first capacitor C1 is_C1Is always lower than the second reference REF2, the second comparator U2 outputs a low level (i.e., a second level). For example, when the power switch 101 is closed, i.e. the sampled signal is greater than the reference signal, then the sampled signal is less than or equal toEqual to the reference signal, and the duration time in this state is less than the time threshold, the first comparator U1 will output a square wave signal, so the first capacitor C1 is continuously discharged and charged, and the voltage V of the first capacitor C1 is_C1Will always fall below the second reference REF2, the second comparator U2 will output a low level. When the power switch 101 is turned off, that is, the sampling signal is less than or equal to the reference signal, and the duration time in this state is greater than the time threshold, the first capacitor C1 is continuously charged, so that the voltage V of the first capacitor C1 is enabled to be constant_C1Above the second reference REF2, the second comparator U2 outputs a high level, see FIG. 5. Therefore, the on/off of the power switch 101 can be detected by the level of the detection signal output by the second comparator U2, that is, whether the input voltage is lower than a reference value, for example, whether the input voltage is under-voltage can be detected by the level of the detection signal output by the second comparator U2.

In a second embodiment, please refer to fig. 6, a first input end of the detection module 200 is connected to a second end of the power switch 101, and a second input end of the detection module 200 is connected to a second output end of the rectifier bridge 102. Or the first input end of the detection module 200 is connected to the second input end of the rectifier bridge 102, and the second input end of the detection module 200 is connected to the second output end of the rectifier bridge 102. That is, the input voltage is sampled to obtain the sampling signal, and other parts are the same as those in the first embodiment, and are not described herein again.

In a third embodiment, referring to fig. 7, the power conversion module 400 includes a power switch and a sampling resistor connected in series, and the positive input terminal of the first comparator U1 of the detection module 200 is connected to the sampling resistor. That is, the voltages at the two ends of the sampling resistor are sampled to obtain the sampling signal, and the other parts are the same as those in the first embodiment and are not described herein again.

The following description will take the input voltage of the detection module 200 as the voltage after the rectifier bridge as an example.

The control module 300 is connected to the detection module 200, and outputs a PWM control signal according to the detection signal of the detection module 200, so as to control the power switch of the power conversion module 400, thereby implementing dimming of the LED.

With continued reference to fig. 4, the control module 300 includes a reference generation module 301, a reference selection module 302, and a driver module 303. The reference generating module 301 is connected to the detecting module 200, and generates a dimming reference signal and a reference compensation maintaining signal according to the detection signal output by the detecting module 200; the reference selection module 302 is connected to the reference generation module 301, and configured to select one of a dimming reference signal and a reference compensation hold signal as a reference signal R-REF, where the reference signal R-REF is the dimming reference signal or the reference compensation hold signal; the driving module 303 is connected to the reference selection module 302, and adjusts the output voltage or current according to the dimming reference signal or the reference compensation hold signal selected by the reference selection module 302.

The reference generation module 301 includes: and a logic signal generating module, an input end of which is connected to the output end of the detection module 200, and which generates a dimming signal V1, a reset signal V2 and a compensation signal V3 according to the detection signal output by the detection module 200. Namely, the first output terminal, the second output terminal and the third output terminal of the logic signal generating module respectively output the dimming signal V1, the reset signal V2 and the compensation signal V3, and the third output terminal thereof is connected to the reference selecting module 302; a dimming reference signal generating module, a first input terminal of which is connected to the first output terminal of the logic signal generating module, a second input terminal of which is connected to the second output terminal of the logic signal generating module, and an output terminal of which is connected to the reference selecting module 302, wherein the dimming reference signal generating module generates a dimming reference signal according to the dimming signal V1, and the output terminal outputs the dimming reference signal; a reference compensation hold signal generating module, a first input terminal of which is connected to the first output terminal of the logic signal generating module, a second input terminal of which is connected to the second output terminal of the logic signal generating module, and an output terminal of which is connected to the reference selecting module 302, wherein the reference compensation hold signal generating module generates a reference compensation hold signal according to the dimming signal V1, and the output terminal outputs the reference compensation hold signal.

Taking the set of first and second levels as a set of actions, the logic signal generation module may include: the device comprises a counter, an acquisition module, a third comparator and a memory. The input end of the counter is connected with the output end of the detection module 200, and counts the detection signals to obtain a count value; an input end of the acquisition module is connected with an output end of the detection module 200, and is used for acquiring the second level duration time in each group of actions; a third comparator, a positive input end of which is connected with the output end of the acquisition module, and a negative input end of which receives the reference value, and is used for comparing the duration of the second level of the previous group of actions with the reference value, and obtaining a time comparison result (the reference value is set to be N seconds, and N is a constant greater than 0); and a memory connected to the third comparator and the counter for storing the corresponding relationship between the count value and the time comparison result and the dimming signal V1, the compensation signal V3 and the reset signal V2.

When the count value is odd, when the second level duration of the upper group action is greater than or equal to the reference value, the logic signal generation module firstly outputs a reset signal V2, the reset signal V2 resets the dimming reference signal and the reference compensation holding signal to the initial value, and then outputs a dimming signal V1, and controls the dimming reference signal to start adjustment from the initial value; when the second level duration of the upper group action is less than the reference value, the logic signal generation module outputs the dimming signal V1, and controls the dimming reference signal to continue to adjust based on the dimming reference signal generated by the upper group action. When the count value is even, the logic signal generation module outputs a compensation signal V3.

When the logic signal generation module outputs the compensation signal V3, the reference selection module 302 selects the reference compensation hold signal as the reference signal R-REF; when the logic signal generation module outputs the dimming signal V1, the reference selection module 302 selects the dimming reference signal as the reference signal R-REF. Therefore, the count value is even, and the reference selection module 302 selects the reference compensation hold signal as the reference signal R-REF; the count value is an odd number and the reference selection module 302 selects the dimming reference signal as the reference signal R-REF.

Referring to fig. 8, the specific steps of dimming include:

s01: for initial power-on, the logic signal generation module outputs a dimming signal V1, the reference selection module 302 selects a dimming reference signal as a reference signal, and the driving module 303 controls the output current to start adjustment from an initial value of the dimming reference signal;

s02: controlling the input voltage to be less than or equal to a reference value (a reference signal is used for representing the reference value) for the first time, controlling the state duration to be greater than or equal to a time threshold value, and then controlling the input voltage to be greater than the reference value;

s03: selecting the reference compensation holding signal as a reference signal, and controlling the output current to be a current value corresponding to the reference compensation holding signal by the driving module 303;

s04: judging whether the brightness of the LED lamp is an expected value or not, and ending the dimming action if the brightness of the LED lamp reaches the expected value; if the brightness of the LED lamp does not reach the expected value, the step S05 is carried out;

s05: controlling the input voltage to be smaller than or equal to the reference value for the second time, and controlling the input voltage to be larger than the reference value after the state duration is larger than or equal to the time threshold;

s06: comparing the duration of the last time that the input voltage is greater than the reference value with the reference value, if the duration is greater than the reference value, returning to step S01; if the duration is less than or equal to the reference value, the process proceeds to step S07:

s07: the logic signal generation module outputs the dimming signal and continues dimming based on the upper set of dimming reference signals, and returns to step S02. And sequentially circulating until the brightness of the LED lamp is a desired value.

In a first embodiment, the dimming reference signal generation module comprises: a second switch tube Q2, a fourth switch tube Q4 and a second capacitor C2. The control terminal of the second switch tube Q2 is connected to the first output terminal of the logic signal generating module and receives a dimming signal V1, the first terminal of the second switch tube Q2 is connected to the second terminal of the second current source I2, the first terminal of the second current source I2 receives a third reference REF3 for charging a second capacitor C2, and the third reference REF3 defines a maximum value of a reference for clamping. A second end of the second switch tube Q2 is connected with a first end of the second capacitor C2; the control end of the fourth switching tube Q4 is connected with the second output end of the logic signal generating module, receives a reset signal V2, and is used for controlling the fourth switching tube Q4 to discharge to the second capacitor C2, the first end of the second capacitor C2 is connected with the first end of the fourth switching tube, and the second end of the second capacitor C2 is connected with the second end of the fourth switching tube.

The reference compensation hold signal generation module includes: a third switch tube Q3, a fifth switch tube Q5 and a third capacitor C3. A control terminal of the third switching tube Q3 is connected to the first output terminal of the logic signal generating module and receives a dimming signal V1, a first terminal of the third switching tube Q3 is connected to a second terminal of the third current source I3 and is configured to charge a third capacitor C3, a first terminal of the third current source I3 receives a third reference REF3, and a second terminal of the third switching tube Q3 is connected to the first terminal of the third capacitor C3; the control end of the fifth switching tube Q5 is connected with the second output end of the logic signal generating module; receiving a reset signal V2, configured to control a fifth switching transistor Q5 to discharge a third capacitor C3, where a first end of the third capacitor C3 is connected to a first end of the fifth switching transistor Q5, and a second end of the third capacitor C3 is connected to a second end of the fifth switching transistor Q5.

When the dimming signal V1 output by the first output terminal of the logic signal generating module is at a high level (i.e., when the logic signal generating module outputs the dimming signal V1), the second switch Q2 and the third switch Q3 are closed, so that the second current source I2 can charge the second capacitor C2, and the third current source I3 can charge the third capacitor C3.

In this embodiment, the capacitance values of the second current source I2, the third current source I3, the second capacitor C2 and the third capacitor C3 can be set to adjust the capacitance value of the third capacitor C3The charging speed of the second capacitor C2 and the charging speed of the third capacitor C3 are made to be higher than the charging speed of the third capacitor C3, and at this time, the voltage V of the second capacitor C2_C2The voltage V of the third capacitor C3 is used as a reference signal for dimming_C3The hold signal is compensated for reference. Referring to fig. 9, when the user wants to output a current corresponding to the current value at the time point t1, the power switch 101 is turned off, and the real turn-off operation is actually performed at the time point t2 (i.e. the difference between the time point t2 and the time point t1 is the human body reaction time), so that during the period t1-t2, the voltage V of the second capacitor C2 is equal to the voltage V of the second capacitor C2_C2Continues to increase, and the third capacitor C3 has a voltage V of 3 due to the hysteresis of charging_C3At the time point of t2, the voltage V of the second capacitor C2 corresponding to the time point of t1 is just reached_C2. Therefore, the required compensation time can be obtained by measuring the human body reaction speed, so as to obtain the parameter configuration (i.e. the capacitance parameters of the second current source I2, the third current source I3, the second capacitor C2 and the third capacitor C3). The method specifically comprises the following steps: the capacitance values of the second capacitor C2 and the third capacitor C3 can be obtained through the time point t1 and the time point t2 and the sizes of the second current source I2 and the third current source I3, that is, the capacitance values of the second capacitor C2 and the third capacitor C3 can be obtained according to the formula I ═ C × du/dt. Alternatively, a second capacitor C2 and a third capacitor C3, which are known per se, are provided to obtain the size of the second current source I2 and the third current source I3.

When the reset signal V2 output by the second output terminal of the logic signal generating module is at a high level (i.e., the logic signal generating module outputs the reset signal V2), the fourth switching tube Q4 and the fifth switching tube Q5 are closed, and the voltages of the second capacitor C2 and the third capacitor C3 are discharged.

The reference selection module 302 is connected to the reference generation module 301, and is configured to select a reference signal R-REF, where the reference signal R-REF is one of the dimming reference signal and the reference compensation hold signal.

The reference selection module 302 includes a sixth switching tube Q6 and a seventh switching tube Q7. The control terminal of the sixth switching tube Q6 is connected to the first output terminal of the logic signal generating module and receives the dimming signal V1, the first terminal of the sixth switching tube Q6 is connected to the first terminal of the fourth switching tube Q4, and the second terminal thereof is connected to the driving module 303. A control terminal of the seventh switch Q7 is connected to the third output terminal of the logic signal generating module for receiving the compensation signal V3, a first terminal of the seventh switch Q7 is connected to the first terminal of the third capacitor C3, and a second terminal thereof is connected to the driving module 303.

When the first output terminal of the logic signal generating module outputs the dimming signal V1 with a high level, the sixth switching tube Q6 is closed, and the dimming reference signal is transmitted to the driving module 303; when the third output terminal of the logic signal generating module outputs the compensation signal V3 with a high level, the reference compensation holding signal is transmitted to the driving module 303. With continued reference to FIG. 9, the reference signal R-REF is the voltage V of the second capacitor C2 during the period from the first power-up (the count value is 1) to the real (t2 time point) turn-off of the power switch 101_C2When the switch is turned off at the time point t2, the dimming signal V1 is inverted to a low level, and the output of the voltage V of the second capacitor C2 is stopped_C2That is, the dimming reference signal stops being output, and the next time the power switch 101 is closed (the count value is 2), at time t3, the compensation signal V3 is high, and the reference signal R-REF is switched to the voltage V of the third capacitor C3_C3If the voltage V of the third capacitor C3 is larger than the voltage V of the second capacitor C3_C3The dimming is finished for the reference signal really expected by the user, otherwise, the power switch 101 is turned off again after being closed for a period of time, the compensation signal V3 is changed to be low level, and the output of the voltage V of the third capacitor C3 is stopped_C3The power switch 101 is closed again (the count value is 3), and if the last time the power switch is closed is less than or equal to the reference value, the reference signal R-REF is a dimming reference signal, that is, the reference signal R-REF is the voltage V of the second capacitor C2 last time_C2And continuously adjusting the adjustment, and circulating in sequence until the user expectation is met.

In the fourth embodiment, different from the first embodiment, the second capacitor C2 and the third capacitor C3 are discharged by a current source, and the principle is the same, which is within the protection scope of the present invention.

For example, referring to fig. 10, when the second capacitor C2 and the third capacitor C3 are respectively discharged by using current sources, the dimming reference signal generating module includes: a second switching tube Q2, a control end of which is connected with the first output end of the logic signal generating module; receiving a dimming signal V1, a second current source I2, a first end of which is connected to the first end of the second switch Q2, and a second end of which is grounded; a fourth switching tube Q4, a control terminal of which is connected to the second output terminal of the logic signal generating module, and receives a reset signal V2, a first terminal of which is connected to the second terminal of the second switching tube Q2, and a second terminal of which receives a third reference; a second capacitor C2, a first terminal of which is connected to the first terminal of the fourth switching tube Q4 and the second terminal of the second switching tube Q2, respectively, and a second terminal of which is grounded.

The reference compensation hold signal generation module includes: a third switching tube Q3, wherein the control end of the third switching tube Q3 is connected with the first output end of the logic signal generating module; receiving a dimming signal V1, a third current source I3, a first end of which is connected to the first end of the third switch tube Q3, and a second end of which is grounded; a fifth switching tube Q5, a control end of which is connected with the second output end of the logic signal generating module; receiving a reset signal V2, and a third capacitor C3, a first end of which is connected to the first end of the fifth switching tube Q5 and the second end of the third switching tube Q3, respectively, and a second end of which is grounded.

The benchmark selection module comprises: a sixth switching tube Q6, a control terminal of which is connected to the first output terminal of the logic signal generating module, and receives a dimming signal V1, a first terminal of which is connected to the first terminal of the fourth switching tube Q4, and a second terminal of which is connected to the driving module 303; a seventh switch Q7, a control terminal of which is connected to the third output terminal of the logic signal generating module, receives a compensation signal V3, a first terminal of which is connected to the first terminal of the third capacitor C3, and a second terminal of which is connected to the driving module 303. The circuit may discharge the second capacitor C2 and the third capacitor C3 through a current source.

Referring to fig. 11, in a fifth embodiment, the dimming reference signal generating module includes: a second switch tube Q2, a fourth switch tube Q4 and a second capacitor C2. The control terminal of the second switch tube Q2 is connected to the first output terminal of the logic signal generating module and receives a dimming signal V1, the first terminal of the second switch tube Q2 is connected to the second terminal of the second current source I2, the first terminal of the second current source I2 receives a third reference REF3, and the third reference REF3 defines a maximum value of a reference for clamping. A second end of the second switch tube Q2 is connected with a first end of the second capacitor C2; the control end of the fourth switch tube Q4 is connected with the second output end of the logic signal generating module, the first end of the second capacitor C2 is connected with the first end of the fourth switch tube to receive a reset signal V2, and the second end of the fourth switch tube is connected with the second end of the fourth switch tube.

The reference compensation hold signal generation module includes: a reference conversion module, an input terminal of which is connected to the first terminal of the second capacitor C2, and an output terminal of which is connected to the reference selection module 302. The reference conversion module is used for converting the voltage V of the second capacitor C2_C2The stepping is performed to generate a reference compensation hold signal.

Referring to fig. 12, the voltage V of the second capacitor C2_C2The voltage V of the stepped second capacitor C2 is used for dimming reference signal_C2The hold signal is compensated for reference. When the user wants to output a current value corresponding to the time point t1, the power switch 101 is turned off, and the real turn-off action is actually at the time point t2, so that the voltage V of the second capacitor C2 is in the period t1-t2_C2The voltage VR2 of the stepped second capacitor C2 has a step, and the voltage VR2 just reaches the voltage V of the second capacitor C2 corresponding to the time point t1 at the time point t2_C2。

The reference selection module 302 includes a sixth switching tube Q6 and a seventh switching tube Q7. The control terminal of the sixth switch Q6 is connected to the first output terminal of the logic signal generating module, the first terminal of the sixth switch Q6 receiving the dimming signal V1 is connected to the first terminal of the second capacitor C2, and the second terminal thereof is connected to the driving module 303. The control end of the seventh switch tube Q7 and the second end of the logic signal generating moduleThe third output end is connected, the first end of the seventh switch tube Q7 receiving the compensation signal V3 is connected to the output end of the reference conversion module, and the second end thereof is connected to the driving module 303. When the first output terminal of the logic signal generating module outputs the dimming signal V1 with a high level, the sixth switching tube Q6 is closed, and the dimming reference signal is transmitted to the driving module 303; when the third output terminal of the logic signal generating module outputs the compensation signal V3 with a high level, the seventh switch Q7 is closed, and the reference compensation holding signal is transmitted to the driving module 303. With continued reference to FIG. 12, the reference signal R-REF is the voltage V of the second capacitor C2 during the period from the first power-up (the count value is 1) to the real (t2 time point) turn-off of the power switch 101_C2At the time point t2, the power switch 101 is turned off, the dimming signal V1 is inverted to a low level, and the output of the voltage V of the second capacitor C2 is stopped_C2That is, the dimming reference signal stops being output, and the next time the power switch 101 is closed (the count value is 2), at time t3, the compensation signal V3 becomes high, and the reference signal R-REF is switched to the voltage V of the stepped second capacitor C2_R2If said voltage V is_R2The dimming is finished for the reference signal really expected by the user, otherwise, the power switch 101 is turned off again after being closed for a period of time, the compensation signal V3 is changed to low level, and the output voltage V is stopped_R2The power switch 101 is closed again (the count value is 3), and if the last time the power switch is closed is less than or equal to the reference value, the reference signal R-REF is a dimming reference signal, that is, the reference signal R-REF is the voltage V of the second capacitor C2 last time_C2Continues to adjust, cycling in turn, until the user's expectations are met.

Referring to fig. 13, in a sixth embodiment, the reference compensation hold signal generating module includes: a second switch tube Q2, a first pulse module M1 and a first digital-to-analog conversion module. The control end of the second switching tube Q2 is connected with the first output end of the logic signal generating module; the first pulse module M1 is connected to a first end of the second switch tube Q2; the first input end of the first digital-to-analog conversion module is connected to the second output end of the logic signal generation module, the second input end of the first digital-to-analog conversion module is connected to the second end of the second switch Q2, and the output end of the first digital-to-analog conversion module is connected to the reference selection module 302.

The reference compensation hold signal generation module includes: a third switch tube Q3, a second pulse module M2 and a second digital-to-analog conversion module. The control end of the third switching tube Q3 is connected with the first output end of the logic signal generating module; the second pulse module M2 is connected with the first end of the third switch tube Q3; the first input end of the second digital-to-analog conversion module is connected to the second output end of the logic signal generation module, the second input end thereof is connected to the second end of the third switch Q3, and the output end thereof is connected to the reference selection module 302.

The input end of the logic signal generating module is connected to the output end of the detecting module 200, and the first output end, the second output end and the third output end of the logic signal generating module respectively output the dimming signal V1, the reset signal V2 and the compensation signal V3.

The pulse frequency of the first pulse module M1 is set faster than that of the second pulse module M2. When the first output terminal of the logic signal generating module outputs the dimming signal V1 with a high level, the pulse signal CLK1 generated by the first pulse module M1 is transmitted to the first digital-to-analog conversion module, and the pulse signal CLK2 generated by the second pulse module M2 is transmitted to the second digital-to-analog conversion module, so that the slope of the first conversion signal R-R1 corresponding to the first pulse module M1 changes faster due to the fast pulse frequency generated by the first pulse module M1. Referring to fig. 14, it can be seen that, the slope of the first conversion signal R-R1 corresponding to the first pulse module M1 is greater than the slope of the second conversion signal R-R2 corresponding to the second pulse module M2, so that the first conversion signal R-R1 is used as the dimming reference signal and the second conversion signal R-R2 is used as the reference compensation hold signal. When the user wants to output a current value corresponding to the time point t1, the power switch 101 is turned off, and the real turn-off action is actually at the time point t2, so during the time period t1-t2, the first conversion signal R-R1 continues to increase, while the second conversion signal R-R2 is slower due to the increasing speed, and the second conversion signal R-R2 just reaches the first conversion signal R-R1 corresponding to the time point t1 at the time point t 2.

The reference selection module 302 includes a sixth switching tube Q6 and a seventh switching tube Q7. The control end of the sixth switching tube Q6 is connected to the first output end of the logic signal generating module, the first end of the sixth switching tube Q6 is connected to the output end of the first digital-to-analog converting module, and the second end of the sixth switching tube Q6 is connected to the driving module 303. A control terminal of the seventh switch Q7 is connected to the third output terminal of the logic signal generating module, a first terminal of the seventh switch Q7 is connected to the output terminal of the second digital-to-analog converting module, and a second terminal thereof is connected to the driving module 303. When the first terminal of the logic signal generating module outputs the dimming signal V1 with a high level, the sixth switching tube Q6 is closed, and the dimming reference signal is transmitted to the driving module 303; when the third terminal of the logic signal generating module outputs the compensation signal V3 with a high level, the reference compensation holding signal is transmitted to the driving module 303. With continued reference to fig. 14, the reference signal R-REF is the first conversion signal R-R1 during the period from the first power-up (the count value is 1) to the time when the power switch 101 is actually turned off (the time point t 2), the dimming signal V1 is turned off at the time point t2, the first conversion signal R-R1 is stopped being output, i.e., the dimming reference signal is stopped being output, next time the power switch 101 is closed (the count value is 2), the compensation signal V3 is high at the time point t3 to switch the reference signal R-REF to the second conversion signal R-R2, if the second conversion signal R-R2 is the reference signal really desired by the user, the dimming is ended, otherwise, the power switch-off operation is performed again after the power switch 101 is closed for a while, the compensation signal V3 is turned to low, the second conversion signal R-R2 is stopped being output, closing the power switch 101 again (the count value is 3), and if the last closing time of the power switch is less than or equal to the reference value N, the reference signal R-REF is a dimming reference signal, that is, the reference signal R-REF continues to be adjusted on the basis of the last first conversion signal R-R1, and the steps are sequentially circulated until the user's expectation is met.

The input end of the driving module 303 is connected to the reference selection module 302, and the output end thereof is connected to the power conversion module 400. The driving module 303 generates a PWM control signal according to the reference signal R-REF selected by the reference selection module 302 to adjust the output current or voltage signal. The power conversion module 400 outputs a dc current or a dc voltage according to the PWM control signal to provide energy to the LED load.

The utility model provides a LED drive circuit and dimming system of adjusting luminance can produce simultaneously through the benchmark and adjust luminance the reference signal and the benchmark compensation keeps the signal, and keeps the actual reference signal that the signal compensation shutdown time delay caused and expects the difference between the reference signal through the benchmark compensation. Therefore, the LED dimming driving circuit and the dimming system can solve the problem of brightness overshoot caused by shutdown action delay, so that the dimming experience of a user is improved.

The above description is only for the preferred embodiment of the present invention and is not intended to limit the scope of the present invention, and any modification and modification made by those skilled in the art according to the above disclosure are all within the scope of the claims.

Claims

1. An LED dimming driving circuit, comprising:

2. The LED dimming driver circuit of claim 1, wherein the dimming reference signal is selected as the reference signal when the LED lamp brightness does not reach a desired brightness value.

3. The LED dimming drive circuit of claim 1 or 2, wherein the dimming reference signal has a variation greater than or equal to a variation of the reference compensation hold signal at the same time.

4. The LED dimming driving circuit according to claim 1 or 2, further comprising a detection module generating a detection signal according to a sampling signal representing the input voltage and a reference signal, wherein when the sampling signal is less than or equal to the reference signal and the duration of the state is greater than or equal to a time threshold, the state of the detection signal output by the detection module is a first level, and otherwise, the state of the detection signal output by the detection module is a second level.

5. The LED dimming drive circuit of claim 4, wherein the reference generation module comprises:

6. The LED dimming drive circuit of claim 5, wherein the reference generation module further comprises:

7. The LED dimming driving circuit according to claim 6, wherein the reference selection module is respectively connected to the dimming reference signal generation module, the reference compensation hold signal generation module and the logic signal generation module, and when the count value is an even number, the logic signal generation module outputs the compensation signal and controls the reference selection module to select the reference compensation hold signal as the reference signal; and when the count value is odd, the logic signal generation module outputs a dimming signal and controls the reference selection module to select the dimming reference signal as the reference signal.

8. The LED dimming driver circuit of claim 7, wherein the brightness of the LED lamp is continuously adjusted by controlling the dimming reference signal to gradually increase or gradually decrease.

9. The LED dimming driver circuit of claim 5, wherein the logic signal generation module further generates a reset signal that resets the dimming reference signal and the reference compensated hold signal to initial values.

10. The LED dimming drive circuit of claim 9, wherein the set of first and second levels act as a set, the logic signal generation module comprising:

11. The LED dimming driving circuit of claim 9, wherein when the count value is odd and the duration of the second level of the upper group is greater than or equal to the reference value, the logic signal generating module outputs the reset signal first and then outputs the dimming signal, and controls the dimming reference signal to start adjusting from the initial value; when the second level duration of the upper group action is less than the reference value, the logic signal generation module outputs a dimming signal and controls the dimming reference signal to continue to be adjusted on the basis of the dimming reference signal generated by the upper group action.

12. The LED dimming drive circuit of claim 6, wherein the dimming reference signal generation module comprises:

13. The LED dimming drive circuit of claim 12, wherein the reference compensation hold signal generation module comprises:

and a first end of the third capacitor is connected with a first end of the fifth switching tube and a second end of the third switching tube respectively, the third current signal charges the third capacitor to generate a reference compensation holding signal, and the charging speed of the second capacitor is greater than that of the third capacitor.

14. The LED dimming drive circuit of claim 12, wherein the reference compensation hold signal generation module comprises:

and the input end of the reference conversion module is connected with the first end of the second capacitor, the output end of the reference conversion module is connected with the reference selection module, and the reference conversion module receives the dimming reference signal, carries the dimming reference signal in a stepped manner and generates a reference compensation holding signal.

15. The LED dimming drive circuit of claim 6, wherein the dimming reference signal generation module comprises:

16. The LED dimming drive circuit of claim 15, wherein the reference compensation hold signal generation module comprises:

17. The LED dimming drive circuit of claim 6, wherein the dimming reference signal generation module comprises:

and a first input end of the first digital-to-analog conversion module is connected with the logic signal generation module and receives a reset signal, and a second input end of the first digital-to-analog conversion module is connected with a second end of the second switching tube and generates a dimming reference signal according to the first pulse signal.

18. The LED dimming drive circuit of claim 17, wherein the reference compensation hold signal generation module comprises:

19. The LED dimming drive circuit of claim 18, wherein the first pulse module generates a pulse frequency that is greater than a pulse frequency generated by the second pulse module.

20. The LED dimming driver circuit of claim 19, wherein the first and second digital-to-analog conversion modules receive a reset signal and reset the dimming reference signal and the reference compensation hold signal to initial values when the logic signal generation module outputs the reset signal.

21. The LED dimming drive circuit of claim 13, 14, 16 or 18, wherein the reference selection module comprises:

and the control end of the seventh switching tube is connected with the output end of the logic signal generation module and receives the compensation signal, and the first end of the seventh switching tube is connected with the reference compensation maintaining signal and receives the reference compensation maintaining signal, and the seventh switching tube is turned off or closed according to the compensation signal to control the output of the reference compensation maintaining signal.

22. A dimming system, comprising:

the LED dimming drive circuit of any one of claims 1 to 21, which generates a control signal according to the sampling signal;

23. The dimming system of claim 22, wherein the power conversion module comprises a power switch and a sampling resistor, the power switch and the sampling resistor connected in series,

24. The dimming system of claim 22, further comprising:

and sampling the rectified input voltage to obtain the sampling signal.

25. The dimming system of claim 22, further comprising:

wherein the sampling signal is obtained by sampling the input voltage.