CN114650636B - Method and circuit system for realizing ultra-low brightness dimming - Google Patents

Method and circuit system for realizing ultra-low brightness dimming Download PDF

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CN114650636B
CN114650636B CN202210544572.0A CN202210544572A CN114650636B CN 114650636 B CN114650636 B CN 114650636B CN 202210544572 A CN202210544572 A CN 202210544572A CN 114650636 B CN114650636 B CN 114650636B
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control signal
current
pwm
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CN114650636A (en
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杨应森
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Guangdong Nanguang Television Equipment Co ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/345—Current stabilisation; Maintaining constant current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

The invention discloses a method for realizing ultra-low brightness dimming, which comprises the steps of dimming a signal, generating a control signal, and enabling the control signal and the dimming signal to be in a direct proportion relation and the minimum value to be larger than 0; generating a driving current, making the driving current and the control signal in a direct proportion relation, and when the control signal is a minimum value, the driving current is greater than 0; generating a demand current, keeping the demand current constant or in a linear relation with the control signal, and enabling the demand current to be equal to the driving current when the control signal is the minimum value; the driving current is divided into two paths, wherein one path is used for meeting the requirement of the required current, and the other path is used for driving the lamp. The invention also discloses a dimming circuit system which can realize ultra-low brightness dimming. The current flowing to the lamp is increased linearly from 0, so that the continuous dimming effect of the lamp from the lowest brightness is realized.

Description

Method and circuit system for realizing ultra-low brightness dimming
Technical Field
The invention relates to a dimming method, in particular to a method for realizing ultralow-brightness dimming, and also relates to a circuit system for realizing ultralow-brightness dimming.
Background
The existing LED lamp dimming mode comprises PWM dimming and analog dimming, and the basic principle of the two modes is that a constant current driving module is controlled by a PWM signal or an analog signal to output driving current to drive an LED lamp, so that the brightness of the LED lamp is adjusted.
In the PWM dimming mode, when the duty ratio of a PWM signal is increased in an extremely large range, the constant current driving module can correspondingly output driving current with high linearity, so that the brightness change of the LED lamp is very uniform. However, when the duty ratio of the PWM signal ranges from 0 to a very small value, the constant current driving module is difficult to effectively identify, which causes the output driving current to fluctuate greatly and cannot be controlled, so that the LED lamp is prone to go out and flash. Due to the influence of component manufacturing processes and the like, the duty ratio ranges of the different constant current driving modules are different, the performance is better between 0 and 0.005, and most of the constant current driving modules are between 0 and 0.3. The prior art selects an LED lamp with a slightly higher lighting current, so that the section with unstable low current can be avoided, but the minimum brightness of the LED lamp is also higher due to the method, and the LED lamp cannot be adjusted to lower brightness.
Analog dimming also suffers from similar problems as PWM dimming. When the level of the analog signal is in the largest range, the constant current driving module can correspondingly output the driving current with high linearity, and when the level is in the range from zero to a small value, the constant current driving module is difficult to effectively identify, so that the driving current fluctuation is large, and the LED lamp is also subjected to the problems of extinguishment, stroboflash and the like. The conventional method is also the same as the method of PWM signals, and an LED lamp with slightly high lighting current is adopted. Therefore, the problem also arises that the minimum brightness of the LED lamp is high and cannot be adjusted to a lower brightness.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a method capable of realizing ultra-low brightness dimming.
The technical scheme adopted by the invention for solving the problems is as follows:
a method for realizing ultra-low brightness dimming comprises generating a dimming signal, generating a control signal, and making the control signal and the dimming signal in a direct proportion relationship, wherein the minimum value is more than 0; generating a driving current, making the driving current and the control signal in a direct proportion relation, and when the control signal is a minimum value, the driving current is greater than 0; generating a demand current, keeping the demand current constant or in a linear relation with the control signal, and when the control signal is the minimum value, the demand current is equal to the driving current; the driving current is divided into two paths, wherein one path is used for meeting the requirement of the required current, and the other path is used for driving the lamp.
In a further improvement, the demand current is in inverse proportion to the control signal.
The control signal is a PWM control signal, the duty ratio of the control signal is continuously increased from an initial value to a final value, and the range of the initial value of the duty ratio is 0.005-0.03; when the duty ratio is any value greater than the initial value and less than or equal to the final value, the required current is 0.
In a further refinement, a PWM demand current control signal is included for controlling the demand current, the demand current being in direct proportion to a duty cycle of the PWM demand current control signal, the duty cycle of the PWM demand current control signal being complementary to the duty cycle of the PWM control signal.
The control signal is an analog control signal, the level of the control signal is continuously increased from an initial value to a final value, and the range of the initial value of the level is 0.01-0.1V; the required current is 0 when the level is any value within a range greater than the initial value and less than or equal to the final value.
The PWM control circuit is further improved by comprising a PWM demand current control signal used for controlling demand current, wherein the demand current is in direct proportion to the duty ratio of the PWM demand current control signal, and the duty ratio of the PWM demand current control signal is complementary to the duty ratio of the PWM demand current control signal after the analog control signal is converted into the PWM signal.
The invention also provides a circuit system for realizing ultra-low brightness dimming, which comprises an LED module and a control signal generation module, wherein the control signal generation module is used for receiving an external dimming signal, generating and outputting a linearly increased control signal, and making the minimum value of the control signal be more than 0; the constant current driving module is used for receiving the control signal output by the control signal generating module and outputting a driving current which is increased along with the increase of the control signal, and the driving current is greater than 0 when the control signal is the minimum value; the demand load module is used for receiving the control signal output by the control signal generation module, adjusting the load of the demand load module according to the control signal to keep the demand input current of the demand load module constant or form a linear relation with the control signal, and when the control signal is the minimum value, the magnitude of the demand input current is equal to that of the driving current; and the driving current of the constant current driving module is respectively output to the demand load module and the LED module.
The load module adjusts the load of the load module according to the PWM control signal after phase inversion, so that the required input current of the load module is in a direct proportion relation with the PWM control signal after phase inversion, and the driving current of the constant current driving module is output to the load module.
The control signal generation module is an analog control signal generation module, the generated control signal is an analog control signal, the demand load module comprises an analog-to-PWM module, a PWM signal inversion module and a load module, the analog-to-PWM module is used for receiving the analog control signal, converting the analog control signal into the PWM control signal and outputting the PWM control signal to the PWM signal inversion module, the PWM signal inversion module inverts the PWM control signal and outputs the PWM control signal to the load module, the load module adjusts the load according to the inverted PWM control signal, the required input current of the load module is in direct proportion to the inverted PWM control signal, and the driving current of the constant current driving module is output to the load module.
The load module comprises an X10S constant current chip, a capacitor C10, a resistor R10, an R11, an R12, an R13 and an R14, wherein two GND pins of the X10S constant current chip are grounded respectively, a VCC pin is connected with 12V power supply voltage after passing through the resistor R10, a REXT pin is grounded after passing through a resistor R13, a DIM pin is connected with an output end of the PWM signal phase inversion module after passing through the resistor R11 and used for receiving PWM control signals after phase inversion, an IOUT pin is connected with a driving current output end of the constant current driving module after passing through a resistor R14, two terminals of the capacitor C10 are connected with the VCC pin and the adjacent GND pins respectively, and two terminals of the resistor R12 are connected with the DIM pin and the ground respectively.
The invention has the beneficial effects that: the control signal of the invention is in direct proportion with the dimming signal, the minimum value is more than 0, the driving current is also in direct proportion with the control signal, when the control signal is the minimum value, the driving current is more than 0, when the control signal is the minimum value, the part of the control signal from 0 to the minimum value and the driving current which corresponds to the part and is uncontrollably changed are shielded, only a linear subsequent part is left, in addition, a demand current which is kept constant or is in linear relation with the control signal are further generated, and the driving current is respectively used for meeting the demand of the demand current and driving the lamp, so that the current flowing to the lamp is equal to the driving current minus the demand current, and because the demand current is equal to the driving current when the control signal is the minimum value, the minimum value of the current flowing through the lamp is reduced to 0 and is increased along with the increase of the control signal, the finally obtained current flowing to the lamp increases linearly from 0, so that the dimming effect that the brightness of the lamp is continuous from the lowest is realized.
Drawings
FIG. 1 is a block diagram of the circuit of the present invention when the control signal is a PWM control signal;
FIG. 2 is a block diagram of the circuit of the present invention when the control signal is an analog control signal;
FIG. 3 is a circuit schematic of the load module of the present invention;
FIG. 4 is a graph of a portion of a prior art PWM signal versus drive current;
FIG. 5 is a global graph of the relationship between drive current and lamp current when the demand current increases linearly in accordance with the present invention;
FIG. 6 is a global graph of the relationship between the drive current and the lamp current when the demand current is linearly constant according to the present invention;
FIG. 7 is a global coordinate diagram of a first embodiment of the present invention;
FIG. 8 is a partial graph of a first embodiment of the present invention;
FIG. 9 is a global coordinate diagram of a second embodiment of the present invention;
FIG. 10 is a partial graph of a third embodiment of the present invention;
FIG. 11 is a global coordinate diagram of a fourth embodiment of the present invention;
fig. 12 is a partial graph of a fifth embodiment of the present invention.
Detailed Description
The conception, the specific structure and the technical effects of the present invention will be clearly and completely described in the following with reference to the embodiments and the accompanying drawings, so as to fully understand the objects, the features and the effects of the present invention. The technical characteristics in the invention can be interactively combined to form a new embodiment on the premise of not conflicting with each other.
A method for realizing ultra-low brightness dimming solves the problem that the prior art cannot realize ultra-low brightness dimming. The method comprises the steps that a dimming signal input from the outside is firstly generated, a control signal which is in a direct proportion relation with the dimming signal and the minimum value of the control signal is larger than 0 is generated, secondly, a driving current which is in a direct proportion relation with the control signal is generated, and when the control signal is the minimum value, the driving current is larger than 0; generating a demand current while generating the driving current, keeping the demand current constant or in a linear relation with the control signal, and enabling the demand current to be equal to the driving current when the control signal is the minimum value; and finally, dividing the driving current into two paths, wherein one path is used for meeting the requirement of the required current, and the other path is used for driving the lamp.
In the dimming method, the control signal, the driving current and the required current are in a proportional relation or linearly changed or constant, and are influenced by the manufacturing process of components, the use environment and the like in practice, so that the absolutely linearly changed or constant signal or current cannot be obtained, and the signal or current which is still linear in the whole and fluctuates in a small amplitude in practice is considered to belong to a proportional relation or linearly changed or kept constant. In this method, the control signal is used to control and adjust the driving current, and in fact, when the control signal is small, the driving current is difficult to obtain a small current value, and a variation which is difficult to control, such as a ripple, is easy to occur, as shown in fig. 4. Therefore, by making the minimum value of the control signal larger than 0 and making the driving current larger than 0 when the control signal is at the minimum value, the part of the driving current which is difficult to control is shielded, and the subsequent part which has good linearity and is controllable is left. The part difficult to control is inherent defects caused by design parameters, processing technology and the like of components, so that the minimum value of a control signal and the corresponding magnitude of a driving current are different when a circuit consisting of different components is adopted and the driving current with linear change is finally obtained. The better the performance of the components and parts, the more reasonable the design of the circuit, the smaller the part which is difficult to control, and the larger the part is otherwise. The minimum value of the control signal and the corresponding drive current have no absolute value and should be determined according to the actual circuit situation.
The dimming method is a dimming method which is constructed to generate the required current to shunt a part of the driving current, so that the current flowing to the lamp is increased linearly from 0, and the dimming can be started from very low brightness. The purpose of the required current is shunting, and when the control signal is the minimum value, the required current is equal to the driving current, so that the lamp current can be reduced to 0. The demand current remains constant or is linearly related to the control signal, wherein the linear relationship includes a linear increase and a linear decrease, i.e. a direct ratio and an inverse ratio. When the required current linearly increases, the relation between the required current and the driving current and the lamp current is shown in the attached figure 5; and when the required current is constant, the relation between the required current and the driving current and the lamp current is shown in fig. 6. In both cases, the lamp current is always lower than the driving current, and the phase difference continues to increase or remain the same as the driving current increases. To reduce this difference, the demand current is preferably reduced linearly, i.e. in inverse proportion to the control signal, see fig. 7 to 12. The required current is linearly reduced, and when the control signal is increased, the difference between the lamp current and the driving current is gradually reduced or even disappears.
In the dimming method, the control signal has two implementation modes, namely a PWM mode and an analog mode, and the implementation modes are as follows:
in the first embodiment, the control signal is a PWM control signal, and the duty ratio thereof includes an initial value and a final value and continuously changes in the interval. The duty ratio is a parameter for describing the PWM mode signal, and the larger the duty ratio is, the larger the corresponding PWM control signal is. Since the magnitude of the control signal corresponds to the magnitude of the control driving current, the duty ratio from 0 to the initial value is masked to obtain the linearly varying driving current. Specifically, the range of the initial value of the duty ratio is 0.005-0.03, the range is suitable for most components, and for components with high performance, the duty ratio in the range of 0-0.005 is only required to be shielded; for poor performance, the duty ratio in the range of 0-0.03 needs to be shielded; the performance is between the two, and a certain value in the range is taken according to the actual performance for masking. The final value of the PWM control signal is generally a maximum value of 1, and may be any value greater than the initial value and less than 1 according to actual needs.
In the first embodiment, when the duty ratio of the PWM control signal is any value within a range from the initial value to the final value, the required current is 0, and the required current and the duty ratio of the PWM control signal are in a proportional relationship. The required current reaches a maximum value at the initial value of the duty ratio, and gradually decreases to 0 as the duty ratio increases. When the required current is 0, the more the duty ratio of the corresponding PWM control signal is close to the initial value, the more rapid the change of the required current is, whereas when the required current is 0, the more the corresponding duty ratio is close to the final value, the more gradual the change of the required current is, and the current change graphs are shown in fig. 7 to 10. When the duty ratio of the PWM control signal is any value other than the final value and the required current is 0, the current of the lamp at this time and thereafter is equal to the driving current, that is, the lamp current is composed of two segments: the first segment is formed by subtracting the demand current from the driving current before the demand current is 0; the second stage is constituted by the drive current after the required current is 0, as shown in fig. 9 and 10. Because the lamp current is composed of two sections, the change of the adjustment linearity can occur when the two sections are changed, the dimming effect is influenced, and more importantly, when the required current is suddenly changed into 0, the problem of interference is easy to occur, so that the lamp brightness is suddenly changed. Therefore, it is preferable that the duty ratio of the PWM control signal is equal to the final value, the required current is 0, and in this case, the lamp current is always formed by subtracting the required current from the driving current, so as to avoid various problems that may occur when the required current becomes 0 in the middle, and the current variation graphs thereof are shown in fig. 7 and 8.
In the first embodiment, in order to adjust the required current conveniently, the required current is controlled by the PWM required current control signal, so that the required current and the duty ratio of the PWM required current control signal are in a direct proportion relationship, and the duty ratio of the PWM required current control signal is complementary to the duty ratio of the PWM control signal. The duty ratio complementation means that the two duty ratios are added to be equal to 1, under the condition, the duty ratio of the PWM demand current control signal is reduced along with the increase of the duty ratio of the PWM control signal, so that the PWM demand current control signal is reduced along with the increase of the duty ratio of the PWM control signal, and finally the demand current is also linearly reduced along with the decrease of the demand current.
In the second embodiment, the control signal is an analog control signal whose level continuously changes from an initial value to a final value. The analog control signal changes with the change of the level, and the larger the level is, the larger the analog control signal is. The range of the initial value of the level is 0.01-0.1V. Similar to the PWM control signal, the initial value of the level can satisfy most components in this range, and the level from 0 to the initial value is masked, so that a linearly varying drive current can be obtained. The high-performance component only needs to shield the 0-0.01V part, and the low-performance component only needs to shield the 0-0.1V part. The specific initial value is determined by the performance of the actual component. More preferably, the initial value range is 0.0165-0.1V. When the level is greater than the initial value and less than or equal to any value within the final value, the required current is 0, and the required current linearly decreases. Similarly to the first embodiment, when the level is any value other than the final value and the required current is 0, the lamp current is composed of two stages: the first segment is formed by subtracting the demand current from the driving current before the demand current is 0; the second stage is constituted by the drive current after the required current is 0, as shown in fig. 11 and 12. It is also preferred that the demand current is 0 when the level of the analog control signal is equal to the final value, so that the lamp current always consists of the drive current minus the demand current.
In the second embodiment, the power supply further includes a PWM demand current control signal for controlling the demand current, and the demand current is in a direct proportion to the duty ratio of the PWM demand current control signal. The duty ratio of the PWM required current control signal is complementary to the duty ratio of the PWM signal converted from the analog control signal. In this case, the PWM demand current control signal decreases as the analog control signal increases, so that the demand current also decreases linearly.
The first embodiment of the dimming method comprises: as shown in fig. 7 and 8, the control signal is a PWM control signal, the initial value of the duty ratio is 0.03, the final value is 1, and the duty ratio mask in the range of 0 to 0.03 is not used. When the duty ratio is equal to 0.03, the driving current and the required current are both 0.04A, and when the duty ratio is equal to 1, the driving current is 5A and the required current is 0. When the duty ratio is increased from 0.03 to 1, the lamp current is linearly increased from 0 to 5A, and the lamp current can drive the lamp from 0, so that dimming is realized from ultralow brightness.
Embodiment two of the present dimming method: as shown in fig. 9, the control signal is a PWM control signal, and the initial value of the duty ratio is equal to 0.03 as in the embodiment, and the driving current and the required current are also 0.04A. When the duty ratio is equal to 1, the drive current is 5A, and when the duty ratio is 0.5, the required current is 0. The lamp current increases linearly from 0 to 2.4A when the duty cycle is increased from 0.03 to 0.5, and equals the drive current when the duty cycle is increased from 0.5 to 1.
Embodiment three of the present dimming method: as shown in the partial graph of fig. 10, the control signal is a PWM control signal, the initial value of the duty ratio is 0.01, and when the duty ratio is equal to 0.01, the drive current and the required current are also 0.04A. At a duty ratio of 0.05, the required current is 0. The lamp current increases linearly from 0 to 0.235A when the duty cycle increases from 0.01 to 0.05, and equals the drive current when the duty cycle continues to increase from 0.05.
The fourth embodiment of the dimming method: as shown in fig. 11, the control signal is an analog control signal, the initial value of the level is 0.1V, the final value is 3.3V, and the level mask in the range of 0 to 0.1V is not used. When the level is equal to 0.01V, the driving current and the required current are both 0.05A, and when the level is equal to 3.3V, the driving current is 5A and the required current is 0. When the level is increased from 0.01V to 3.3V, the lamp current is linearly increased from 0 to 5A, so that the lamp current can drive the lamp from 0 to realize dimming from ultra-low brightness.
In the fifth embodiment of the dimming method, as shown in the local graph of fig. 12, the control signal is an analog control signal, and the initial value of the level thereof is 0.66V. When the level is 0.66V, the drive current and the demand current are also 0.04A. At a level of 0.231V, the required current is 0. The lamp current increases linearly from 0 to 0.285A when the level increases from 0.66V to 0.231V, and equals the drive current when the level continues to increase from 0.231V.
The five embodiments just list the relationship between the driving current, the required current and the lamp current in the case of the duty cycle, the initial and final values of the level and the corresponding individual values of the duty cycle or level when the required current is 0, and the relationship between the currents at other values of these variable parameters can be obtained by the internal relationship reflected in the embodiments, and is not exhaustive here.
The invention also provides a dimming circuit system which can realize ultra-low brightness dimming. The LED constant current driving circuit mainly comprises an LED module, a control signal generation module, a constant current driving module and a demand load module. The control signal generation module is used for receiving an external dimming signal, generating and outputting a control signal in a direct proportion relation with the dimming signal, and enabling the minimum value of the control signal to be larger than 0; the constant current driving module is used for receiving the control signal output by the control signal generating module and outputting a driving current which is in direct proportion to the control signal, and the driving current is greater than 0 when the control signal is the minimum value; the demand load module is used for receiving the control signal output by the control signal generation module, adjusting the load of the demand load module according to the control signal to keep the demand input current of the demand load module constant or to be in a linear relation with the control signal, and when the control signal is the minimum value, the demand input current is equal to the drive current in magnitude; and the driving current of the constant current driving module is respectively output to the demand load module and the LED module. In the dimming circuit, the demand load module shunts the driving current by generating a demand input current, so that the current flowing to the LED module is reduced to a minimum of 0 and linearly increased from 0.
In the dimming circuit system, the control signal generated by the control signal generation module has two implementation modes of a PWM control model and an analog control signal, which specifically include:
in a first embodiment, referring to fig. 1, the control signal generating module is a PWM control signal generating module, the generated control signal is a PWM control signal, the demand load module includes a PWM signal inverting module and a load module, the PWM signal inverting module is configured to receive the PWM control signal and invert the PWM control signal and output the PWM control signal to the load module, and the load module adjusts a load of the load module according to the inverted PWM control signal, so that a demand input current of the load module is in a direct proportion to the inverted PWM control signal, and when the inverted PWM control signal increases, the demand input current increases linearly. And the driving current of the constant current driving module is output to the load module.
In a second implementation manner, referring to fig. 2, the control signal generation module is an analog control signal generation module, the generated control signal is an analog control signal, the demand load module includes an analog-to-PWM module, a PWM signal inversion module, and a load module, the analog-to-PWM module is configured to receive the analog control signal and convert the analog control signal into a PWM control signal, and output the PWM control signal to the PWM signal inversion module, the PWM signal inversion module inverts the PWM control signal and outputs the PWM control signal to the load module, and the load module adjusts a load according to the inverted PWM control signal, so that a demand input current of the load module is in a direct proportion relation with the inverted PWM control signal, and when the inverted PWM control signal is increased, the demand input current is linearly increased. And the driving current of the constant current driving module is output to the load module.
According to the dimming method, the required input current and the control signal are in inverse proportion, so that the difference between the current flowing to the LED module and the driving current can be gradually reduced or even disappear, and therefore, the required input current is linearly reduced along with the increase of the control signal when being optimized. In the above two embodiments, the LED module, the PWM control signal generation module, the analog control signal generation module, the constant current driving module, the analog-to-PWM module, and the PWM signal inversion module may all adopt the prior art. The load module adjusts the required input current of the load according to the PWM control signal after phase inversion, the two are in a direct proportion relation, the PWM control signal after phase inversion and the original PWM control signal are in an inverse proportion relation, when the PWM signal is increased, the PWM signal after phase inversion is reduced, and the required input current of the load module is reduced along with the reduction.
In addition, the constant current driving module in the first embodiment includes a PWM conversion module, and can convert the input PWM control signal into an analog signal. The constant current driving module in the two embodiments comprises a sampling module and a constant current module, wherein the sampling module is used for detecting the output driving current so that the output driving current does not exceed the maximum rated current.
In both embodiments, the same load module may be used. Referring to fig. 3, the load module includes an X10S constant current chip, a capacitor C10, a resistor R10, an R11, an R12, an R13, and an R14, two GND pins of the X10S constant current chip are respectively grounded, a VCC pin is connected to a 12V power supply voltage through the resistor R10, a REXT pin is grounded through the resistor R13, a DIM pin is connected to a signal output terminal of the PWM signal inversion module through the resistor R11, an IOUT pin is connected to a driving current output terminal of the constant current driving module through the resistor R14, two terminals of the capacitor C10 are respectively connected to the VCC pin and the adjacent GND pins, and two terminals of the resistor R12 are respectively connected to the DIM pin and the ground. When the PWM driving circuit is used, the inverted PWM control signal is input into a DIM pin through a resistor R11, the X10S constant current chip generates a load according to the control signal, and driving current flows into the X10S constant current chip through a resistor R14 so as to meet the requirement of the load on input current.
It should be noted that the above-mentioned embodiments are only used for further illustration of the present invention, and should not be construed as limiting the scope of the present invention, and if the present technology is simply modified, the objects of the present invention can be achieved by substantially the same means, and all of the objects should fall within the scope of the present invention.

Claims (9)

1. A method for realizing ultra-low brightness dimming comprises a dimming signal, and is characterized in that:
generating a simulation or PWM control signal, and enabling the control signal and the dimming signal to be in a direct proportion relation and enabling the minimum value to be larger than 0;
generating a driving current, making the driving current and the control signal in a direct proportion relation, and making the driving current larger than 0 when the control signal is a minimum value;
generating a demand current, wherein the demand current is equal to the driving current when the control signal is the minimum value;
and the demand current is generated by a demand load module, the demand load module comprises an inverting module and a load module, and the generation is carried out according to the following steps:
firstly, the phase inversion module receives a control signal, inverts the control signal and outputs the control signal to the load module;
secondly, the load module receives and adjusts the load of the load module according to the inverted control signal, so that the required current of the load module is in a direct proportion relation with the inverted control signal;
the driving current is divided into two paths, wherein one path is used for meeting the requirement of the required current, and the other path is used for driving the lamp.
2. A method for implementing ultra-low brightness dimming according to claim 1, wherein: the control signal is a PWM control signal, the duty ratio of the control signal is continuously increased from an initial value to a final value, the range of the initial value of the duty ratio is 0.005-0.03, and when the duty ratio is larger than the initial value and smaller than or equal to any value in the final value, the required current is 0.
3. A method for implementing ultra-low brightness dimming according to claim 2, wherein: the inverted PWM control signal is a PWM demand current control signal for controlling demand current, the demand current is in a direct proportion relation with the duty ratio of the PWM demand current control signal, and the duty ratio of the PWM demand current control signal is complementary with the duty ratio of the PWM control signal.
4. A method for implementing ultra-low brightness dimming according to claim 1, wherein: the control signal is an analog control signal, the level of the control signal is continuously increased from an initial value to a final value, and the range of the initial value of the level is 0.01-0.1V; the required current is 0 when the level is any value within a range greater than the initial value and less than or equal to the final value.
5. The method of claim 4, wherein the method further comprises: when the phase inversion module inverts the analog control signal, the analog control signal is firstly converted into a PWM control signal and then inverted, the inverted PWM control signal is a PWM demand current control signal used for controlling demand current, the demand current is in a direct proportion relation with the duty ratio of the PWM demand current control signal, and the duty ratio of the PWM demand current control signal is complementary with the duty ratio of the analog control signal after being converted into the PWM signal.
6. A circuit system for realizing ultra-low brightness dimming comprises an LED module, and is characterized in that: also comprises the following steps of (1) preparing,
the control signal generation module is used for receiving an external dimming signal, generating and outputting an analog or PWM control signal in a direct proportion relation with the dimming signal, and enabling the minimum value of the control signal to be larger than 0;
the constant current driving module is used for receiving the control signal output by the control signal generating module and outputting a driving current which is in direct proportion to the control signal, and the driving current is greater than 0 when the control signal is the minimum value;
the load module adjusts the load of the load module according to the control signal after phase inversion, so that the required input current of the load module is in a direct proportion relation with the control signal after phase inversion, and when the control signal is the minimum value, the required input current is equal to the driving current;
and the driving current of the constant current driving module is respectively output to the load module and the LED module.
7. The circuitry of claim 6, wherein: the control signal generation module is a PWM control signal generation module, the generated control signal is a PWM control signal, the phase inversion module is a PWM signal phase inversion module, the PWM signal phase inversion module is used for receiving the PWM control signal and outputting the PWM control signal to the load module after phase inversion, and the load module adjusts the load of the load module according to the PWM control signal after phase inversion, so that the required input current of the load module and the PWM control signal after phase inversion are in a direct proportion relation.
8. The circuitry of claim 6, wherein: the control signal generation module is analog control signal generation module, and the control signal of generation is analog control signal, the opposition module is including simulation commentaries on classics PWM module and PWM signal opposition module, the simulation changes PWM module and is used for receiving analog control signal and exports PWM signal opposition module after converting it into PWM control signal, PWM signal opposition module exports PWM control signal to the load module after with the opposition, the load module adjusts self load according to PWM control signal after the opposition, makes self demand input current and the PWM control signal after the opposition directly proportional relation.
9. The circuit system for realizing ultra-low brightness dimming according to claim 7 or 8, wherein: the load module comprises an X10S constant current chip, a capacitor C10, resistors R10, R11, R12, R13 and R14, two GND pins of the X10S constant current chip are grounded respectively, a VCC pin is connected with 12V power supply voltage through the resistor R10, a REXT pin is grounded through the resistor R13, a DIM pin is connected with a signal output end of the PWM signal inverting module through the resistor R11, an IOUT pin is connected with a driving current output end of the constant current driving module through the resistor R14, two terminals of the capacitor C10 are connected with the VCC pin and an adjacent GND pin respectively, and two terminals of the resistor R12 are connected with the DIM pin and grounded respectively.
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