WO2018121628A1

WO2018121628A1 - Apparatus for controlling brightness of screen of mobile phone

Info

Publication number: WO2018121628A1
Application number: PCT/CN2017/119112
Authority: WO
Inventors: 胡国辉
Original assignee: 广州兴普电子科技有限公司
Priority date: 2016-12-30
Filing date: 2017-12-27
Publication date: 2018-07-05

Abstract

An apparatus for controlling the brightness of a screen of a mobile phone comprises a mobile phone screen light source (LED light source), a silicon controlled rectifier dimmer (GB1), a rectification processing module, a first constant current controller processing module, a second constant current controller processing module, and an electrolytic capacitor processing module. The first constant current controller processing module can provide an anode forward current needed for maintaining conduction of the silicon controlled rectifier dimmer (GB1), so that the silicon controlled rectifier dimmer (GB1) can be rapidly started in a next cycle, and the problem of screen flickers under the condition of switch switching is avoided; and an implementation circuit has a high power factor value and is easy to adjust; the circuit is simple in structure and low in cost. In addition, stroboscopic components in the screen of the mobile phone are eliminated by means of an electrolytic capacitor of the electrolytic capacitor processing module, and accordingly, the phenomenon of flickers can be avoided. Besides, a working input voltage range is widened, so that the light source of the screen of the mobile phone is kept in a working state when a rectified voltage of a bus is lower than a conduction voltage drop of the light source of the screen of the mobile phone, thereby increasing the luminous efficiency intensity.

Description

Mobile phone screen brightness control device

Technical field

The present invention relates to the field of mobile phone screen technology, and more particularly to a mobile phone screen brightness control device.

Background technique

With the advent of smart phones, mobile phone screens have become the most important component of mobile phones. Generally, in different environments, screen brightness needs to be adjusted according to specific conditions. For example, in a dim environment, the brightness of the mobile phone screen needs to be increased. Or in the strong light, increase the brightness of the mobile phone for the user to view, but in the prior art, the brightness of the screen of the mobile phone is adjusted to cause flicker, and the long-term use is unfavorable to the user's health. How to conveniently adjust the brightness of the screen of the mobile phone is a problem faced by the industry.

Summary of the invention

In view of the above problems, embodiments of the present invention provide a mobile phone screen brightness control device that partially or completely solves the above problems, to avoid the problem of flashing of the screen of the mobile phone in the state of switch switching, and the realization circuit has a high power factor and is easy to implement adjustment. The circuit structure is simple and the cost is low.

In order to solve the above technical problem, the present application adopts the following technical solutions:

A mobile phone screen brightness control device according to an embodiment of the invention includes:

Mobile phone screen light source, rectification processing module, thyristor dimmer, first constant current controller, second constant current controller, electrolytic capacitor, rectifier diode, first sampling resistor, second sampling resistor;

The rectification processing module is connected to an external power supply through the thyristor dimmer, and a normal phase output end of the rectification processing module is connected to one end of the first constant current controller and an anode of the rectifier diode, The negative phase output end of the rectification processing module is connected to the other end of the first constant current controller and grounded, and the control end A of the first constant current controller is grounded through the first sampling resistor and the second sampling resistor, a first sampling resistor and the second sampling resistor are connected by a point C, a cathode of the rectifier diode is connected to an anode of the screen light source of the mobile phone, and a cathode of the rectifier diode is also connected to a cathode of the electrolytic capacitor, the electrolysis a cathode of the capacitor is connected to the cathode of the screen light source of the mobile phone, and a cathode of the electrolytic capacitor is also connected to one end of the second constant current controller, and the other end of the second constant current controller is grounded, and the second constant current is The control terminal B of the controller is grounded through the second sampling resistor;

Wherein when the voltage at the control terminal A of the first constant current controller is greater than the voltage at point C, the first constant current controller is turned on to provide an anode forward required to maintain conduction of the thyristor dimmer Current; the electrolytic capacitor supplies power to the light source when the rectified bus voltage is less than the conduction voltage drop of the light source.

In addition, the third sampling resistor has one end connected to the anode of the screen light source of the mobile phone, and the other end connected to the cathode of the rectifier diode and the anode of the electrolytic capacitor.

Wherein, the rectification processing module is a rectifier bridge stack.

In addition, it also includes an input control switch connected to an external power supply.

Correspondingly, a mobile phone screen brightness control device of the present invention includes:

Mobile phone screen light source;

a thyristor dimmer for controlling the input current of the external power source to adjust the brightness of the screen light source of the mobile phone;

The rectification processing module is connected to the external power source through the thyristor dimmer, and is used for rectifying the input external power source;

a first constant current controller processing module coupled to the rectification processing module for providing an anode forward current required to maintain conduction of the thyristor dimmer;

a second constant current controller processing module is connected to the screen light source of the mobile phone for providing constant current driving for the screen light source of the mobile phone;

The electrolytic capacitor processing module has an electrolytic capacitor connected in parallel with the screen light source of the mobile phone, and is configured to supply power to the screen light source of the mobile phone when the rectified bus voltage is less than the conduction voltage drop of the screen light source of the mobile phone.

The electrolytic capacitor processing module specifically includes an electrolytic capacitor and a rectifier diode, an anode of the rectifier diode is connected to a positive phase output end of the rectification processing module, a cathode of the rectifier diode is connected to a positive electrode of the electrolytic capacitor, and the The anode of the phone screen light source.

The first constant current controller processing module specifically includes: a first constant current controller and a first sampling resistor, where the second constant current controller processing module specifically includes: a second constant current controller and a second sampling a resistor, one end of the first constant current controller is connected to the positive phase output end of the rectification processing module and the anode of the rectifier diode, and the other end is grounded, and at the same time, the control end A of the first constant current controller passes The first sampling resistor and the second sampling resistor are grounded, and the first sampling resistor and the second sampling resistor are connected by a point C, and one end of the second constant current controller is connected to the mobile phone screen The cathode of the light source and the cathode of the electrolytic capacitor are connected, and the other end is grounded, and the control terminal B of the second constant current controller is grounded through the second resistor.

In addition, the method further includes: a third sampling resistor, one end of which is connected to the cathode of the sorting diode and the anode of the electrolytic capacitor, and the other end is connected to the anode of the screen light source of the mobile phone.

Wherein, the rectification processing module is a rectifier bridge stack.

In addition, it includes: an input control switch connected to an external power supply.

A screen brightness control device for a mobile phone according to an embodiment of the present invention includes a screen light source of a mobile phone; a thyristor dimmer for controlling an input current of an external power source to adjust brightness of a screen light source of the mobile phone; and a rectification processing module The silicon control dimmer is connected to the external power supply for rectifying the input external power supply; the first constant current controller processing module is connected to the rectification processing module for providing the thyristor dimmer to be turned on. a required anode forward current; a second constant current controller processing module coupled to the screen light source of the mobile phone for providing constant current driving for the screen light source of the mobile phone; an electrolytic capacitor processing module, an electrolytic capacitor thereof and the mobile phone The screen light sources are connected in parallel for supplying power to the screen light source of the mobile phone when the rectified bus voltage is less than the conduction voltage drop of the screen light source of the mobile phone, and the thyristor adjustment can be maintained by the first constant current controller processing module. The anode forward current required for the light source to turn on, enables the thyristor dimmer to start up quickly when the next cycle starts, avoiding switching at the switch In the state, the screen of the mobile phone flickers, and since the thyristor dimmer is quickly turned on, the active power of the circuit is improved, that is, the realization circuit has a high power factor value, the adjustment is easy, and the circuit structure is simple, and the required cost is relatively high. Low, in addition, the electrolytic capacitor through the electrolytic capacitor processing module eliminates the stroboscopic component passing through the screen light source of the mobile phone, can avoid the stroboscopic phenomenon, and widens the working input voltage range, so that the bus voltage of the mobile phone screen light source after rectification is smaller than the mobile phone screen When the conduction voltage of the light source is lowered, the working state is maintained, and the light effect intensity is improved.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a few embodiments described in the present invention, and other drawings can be obtained from those skilled in the art from the drawings.

1 is a waveform diagram of a bus voltage of a rectified electrolytic capacitor with a screen brightness control device of a mobile phone according to the present invention;

2 is a schematic diagram showing the circuit structure of a first embodiment of a screen brightness control device for a mobile phone according to the present invention;

3 is a schematic diagram showing the circuit structure of a second embodiment of a screen brightness control device for a mobile phone according to the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention are within the scope of the present invention.

The core of the invention is that the screen brightness control device of the mobile phone can provide the screen light source of the mobile phone through the LED light string; the input current of the external power source can be controlled by the thyristor dimmer to adjust the brightness of the screen light source of the mobile phone; The power supply is rectified; the anode forward current required to maintain the conduction of the thyristor dimmer is provided by the first constant current controller processing module; and the screen source of the mobile phone is provided by the second constant current controller processing module The constant current driving; and the electrolytic capacitor processing module supplies power to the screen light source of the mobile phone when the rectified bus voltage is less than the conduction voltage drop of the screen light source of the mobile phone.

It should be noted that, as a specific embodiment, the electrolytic capacitor processing module may include an electrolytic capacitor and a rectifier diode, an anode of the rectifier diode is connected to a positive phase output end of the rectification processing module, and a cathode connection of the rectifier diode is connected. The anode of the electrolytic capacitor and the anode of the screen source of the mobile phone.

In addition, as a specific embodiment, the first constant current controller processing module may include: a first constant current controller and a first sampling resistor, and the second constant current controller processing module may include: a second constant current a controller and a second sampling resistor, one end of the first constant current controller is connected to a positive phase output end of the rectification processing module and an anode of the rectifier diode, and the other end is grounded, and at the same time, the first constant current control The control terminal A of the device is grounded through the first sampling resistor and the second sampling resistor, and the first sampling resistor and the second sampling resistor are connected by a point C, the second constant current controller One end is connected to the cathode of the screen light source of the mobile phone and the negative pole of the electrolytic capacitor, and the other end is grounded, and the control end B of the second constant current controller is grounded through the second resistor.

In summary, the screen brightness control device of the mobile phone according to the embodiment is connected to the rectification processing module through a first constant current controller processing module for providing an anode required for maintaining the conduction of the thyristor dimmer. Forward current; enables the thyristor dimmer to start up quickly when the next cycle starts, avoiding the problem of flashing of the screen light source of the mobile phone during the switching state of the switch, and improving the fast conduction of the thyristor dimmer The active power of the circuit, that is, the realization circuit has high power factor value, easy to realize adjustment, and the circuit structure is simple and the required cost is low; in addition, through the electrolytic capacitor processing module, the electrolytic capacitor is connected in parallel with the screen light source of the mobile phone, When the voltage of the busbar after rectification is less than the conduction voltage drop of the screen light source of the mobile phone, power is supplied to the screen light source of the mobile phone, so that the screen light source of the mobile phone continues to work when the voltage of the busbar after rectification is lower than the conduction voltage drop of the screen light source of the mobile phone. , improve the light efficiency, widen the working input voltage range, and eliminate the electrolytic capacitor through the electrolytic capacitor processing module In addition to the stroboscopic component of the screen source of the mobile phone, stroboscopic phenomena can be avoided.

The following is a specific example.

Referring to Fig. 1, there is shown a diagram of a bus voltage waveform of an electrolytic capacitor after rectification in a mobile phone screen brightness control device according to the present invention.

As shown in the figure, the rectified bus voltage waveform in this embodiment is a non-sinusoidal wave. Specifically, in this embodiment, the thyristor dimmer is turned on at time t1, turned off at time t2, and is turned off at another time. At time t3, the thyristor dimmer is re-conducted, and the cycle is continued. In the range of t2 and t3, the power supply can be supplied to the screen light source through the electrolytic capacitor, that is, within the interval of t2 and t3, the screen of the mobile phone The light source can be kept lit, and will not be described here.

2 is a schematic diagram showing the circuit structure of a first embodiment of a screen brightness control device for a mobile phone according to the present invention.

This embodiment is applicable to a linear single-segment stroboscopic method for dimming. In specific implementation, the thyristor dimmer is used to control the brightness of the screen light source of the mobile phone. In this embodiment, the screen light source of the mobile phone is taken as an example. In a preferred embodiment, the rectification processing module in this embodiment may employ a rectifier bridge stack BR1. The first constant current controller processing module may include a first LED constant current controller and a first resistor, and the second constant current controller processing module may The second LED constant current controller and the second resistor are included, and the electrolytic capacitor processing module may include an electrolytic capacitor and a rectifier diode, an anode of the rectifier diode is connected to a positive phase output end of the rectification processing module, and a cathode connection of the rectifier diode The positive electrode of the electrolytic capacitor and the anode of the LED light source of the mobile phone screen, in addition, facilitate input power control, and may further include a power switch. Specifically, the screen brightness control device of the mobile phone of the embodiment mainly includes:

Power switch S0, thyristor dimmer BG1, rectifier bridge stack BR1, rectifier diode VD1, electrolytic capacitor C1, 2 LED constant current controllers: LED constant current controller 1 (ie, the first LED constant current controller) and LED constant current controller 2 (ie, second LED constant current controller), sampling resistors R1, R2 (ie, first sampling resistor and second sampling resistor), mobile phone screen light source, this embodiment is an LED light source (ie, LED light source, In actuality, the LED light source may be, for example, a light string composed of three LED light beads or a light string composed of other numbers of LED light beads, which is not specifically limited herein, and the connection relationship of each component in the specific circuit is as follows:

The rectifier bridge stack BR1 is connected to the external power supply through the power switch S0 and the thyristor dimmer BG1. The positive phase output of the rectifier bridge stack BR1 is connected to one end of the LED constant current driver 1 and the anode of the rectifier diode VD1, and the rectifier bridge stack BR1 The negative phase output terminal is connected to the other end of the LED constant current driver 1 and grounded. The control terminal A end of the LED constant current driver 1 is grounded through the resistors R1 and R2; the cathode of the rectifier diode VD1 is connected to the anode of the LED light source 1, and the rectifier diode VD1 is simultaneously The cathode is connected to the anode of the electrolytic capacitor C1; the cathode of the electrolytic capacitor C1 is connected to the cathode of the LED light source, and the cathode of the electrolytic capacitor C1 is connected to one end of the LED constant current controller 2, and the control terminal B of the LED constant current controller 2 is grounded through the resistor R2. At the same time, the other end of the LED constant current controller 2 is also grounded.

The working process of the screen brightness control device of the mobile phone of this embodiment is described in detail below:

When the power switch is closed, during the T1 cycle, the adjustable thyristor dimmer BG1 triggers conduction at time t1, and the electrolytic capacitor C1 is charged through the bus bar when the bus voltage Vin>V _{LED light source} (ie, the bus voltage is greater than the LED light source) The conduction voltage drop), the LED light source of the mobile phone screen is bright, during which the electrolytic capacitor C1 is continuously charged. During the T1 cycle, when the bus voltage reaches the maximum, the electric capacity of the electrolytic capacitor C1 is also maximized; and the LED constant current control The device 2 controls the current flowing through the LED light source and the electrolytic capacitor C1 to maintain a constant current. Specifically, the current flowing through the LED light source and the electrolytic capacitor C1 is: I _{LED light source} =Vth/R2; at this time, the LED constant current controller 1 detects and controls At the end point A voltage, when the voltage at point A is less than or equal to the voltage at point C, the LED constant current controller 1 is turned off.

It should be noted that during the T1 period, when the bus voltage Vin is reduced to the Vin<V _{LED light source} (ie, the bus voltage is less than the conduction voltage drop of the LED light source), the electrolytic capacitor C1 supplies power to the LED light source, when the electrolytic capacitor C1 is at both ends. When the voltage is less than the V _{LED light source} , the _{LED light source} of the mobile phone screen is turned off; the LED constant current controller 1 detects the voltage of the control terminal A. When the voltage of the A point is greater than the voltage of the C point, the LED constant current controller 1 is turned on, at time t2. The thyristor dimmer BG1 triggers the shutdown, and the LED constant current controller 1 provides the anode forward current necessary to maintain the thyristor dimmer BG1 conducting.

In the T2 cycle, the thyristor dimmer triggers the conduction at time t3, and the above control process is repeated, and details are not described herein again.

In summary, according to the mobile phone screen brightness control device of the embodiment, the anode forward current required to maintain the conduction of the thyristor dimmer is provided by the constant current controller 1; the thyristor dimmer can be made in the next During the cycle, it can be quickly started, avoiding the problem that the screen light source of the mobile phone flickers in the state of the switch switching, and the fast power-on of the thyristor dimmer improves the active power of the circuit, that is, the circuit has a high power factor value. It is easy to realize adjustment, and the circuit structure is simple, and the required cost is low. In addition, when the rectified bus voltage is lower than the conduction voltage drop of the mobile phone screen light source through the electrolytic capacitor C1, the mobile phone screen light source is supplied with power to make the mobile phone screen light source When the rectified bus voltage is lower than the conduction voltage drop of the screen light source of the mobile phone, the working state is maintained, the light effect intensity is increased, the working input voltage range is widened, and the stroboscopic component of the screen light source passing through the mobile phone can be eliminated by the electrolytic capacitor C1. To avoid stroboscopic phenomena.

The embodiment is applicable to a linear single-segment stroboscopic method for dimming. In specific implementation, the brightness of the screen light source of the mobile phone is controlled by the thyristor dimmer, and the LED lamp load brightness in this embodiment is used as a specific embodiment. The processing module may adopt a rectifier bridge stack BR1, the first constant current controller processing module may include a first LED constant current controller and a first resistor, and the second constant current controller processing module may include a second LED constant current controller and a The two resistors, the electrolytic capacitor processing module may include an electrolytic capacitor and a rectifier diode, an anode of the rectifier diode is connected to a positive phase output end of the rectification processing module, a cathode of the rectifier diode is connected to a positive electrode of the electrolytic capacitor, and the mobile phone The screen light source is the anode of the LED light source. In addition, the input power control is facilitated, and the power switch is further included. In addition to the above embodiment, the embodiment further includes: a third sampling resistor, one end of which is connected to the cathode of the finishing diode and The positive electrode of the electrolytic capacitor is connected to the anode of the LED light source at the other end. Specifically, the mobile phone screen of the embodiment Brightness control means including:

Power switch S0, thyristor dimmer BG1, rectifier bridge stack BR1, rectifier diode VD1, electrolytic capacitor C1, 2 LED constant current controllers: LED constant current controller 1 (ie, the first LED constant current controller) and LED constant current controller 2 (ie, the second LED constant current controller), sampling resistors R1, R2, R3 (ie, the first sampling resistor, the second sampling resistor, and the third sampling resistor), the screen light source of the mobile phone is the LED light source (actual The LED light source, for example, a light string composed of three LED light beads may also be a light string composed of other numbers of LED light beads, which is not specifically limited herein, and the connection relationship of each component in the specific circuit is as follows:

The rectifier bridge stack BR1 is connected to the external power supply through the power switch S0 and the thyristor dimmer BG1. The positive phase output of the rectifier bridge stack BR1 is connected to one end of the LED constant current driver 1 and the anode of the rectifier diode VD1, and the rectifier bridge stack BR1 The negative phase output terminal is connected to the other end of the LED constant current driver 1 and grounded. The control terminal A of the LED constant current driver 1 is grounded through the resistors R1 and R2; the cathode of the rectifier diode VD1 is connected to the anode of the LED light source through the sampling resistor R3. The cathode of the rectifier diode VD1 is connected to the anode of the electrolytic capacitor C1; the cathode of the electrolytic capacitor C1 is connected to the cathode of the LED light source, and the cathode of the electrolytic capacitor C1 is connected to one end of the LED constant current controller 2, and the control terminal B of the LED constant current controller 2 is connected. The ground is connected through the resistor R2 while the other end of the LED constant current controller 2 is also grounded.

When the power switch is closed, during the T1 period, the thyristor dimmer BG1 triggers conduction at time t1, and the rectified bus voltage Vin continues to rise, and the electrolytic capacitor C1 is charged through the bus, and as the bus voltage Vin rises, When the bus voltage Vin>V _{LED light source} (ie, the bus voltage is greater than the conduction voltage drop of the LED light source), the LED light source of the mobile phone screen light source is bright, and the voltage Vin continues to rise, during which the electrolytic capacitor C1 continues to be charged, during the T1 cycle. When the bus voltage reaches the maximum, the power of the electrolytic capacitor C1 also reaches the maximum; and the LED constant current controller 2 controls the current flowing through the LED light source to maintain a constant current. Specifically, the current flowing through the LED light source is: I _{LED light source} =Vth /R2; At this time, the LED constant current controller 1 detects the voltage at the control terminal A, and when the voltage at the point A is less than or equal to the voltage at the point C, the LED constant current controller 1 is turned off.

It should be noted that during the T1 period, when the bus voltage Vin starts to slowly decrease to the Vin<V _{LED light source} (ie, the bus voltage is less than the conduction voltage drop of the LED light source), the electrolytic capacitor C1 passes through the resistor R3 to the screen light source of the mobile phone. The LED light source supplies power, and the presence of the resistor R3 defines the discharge speed of the electrolytic capacitor C1. When the voltage across the electrolytic capacitor C1 is less than the V _{LED light source} , the LED light source is extinguished; and when the bus voltage Vin continues to decrease, the LED constant current controller 1 detects Control terminal A point voltage, when the voltage at point A is greater than the voltage at point C, the LED constant current controller 1 is turned on. At time t2, the thyristor dimmer BG1 is triggered to turn off, and the LED constant current controller 1 is provided for maintenance. The anode forward current necessary for the thyristor dimmer BG1 to turn on.

In the T2 cycle, the thyristor dimmer triggers the conduction again at time t3, and the above control process is repeated, and details are not described herein again.

In summary, the screen brightness control device of the mobile phone of the embodiment drives the LED light source of the mobile phone screen through the constant current driver 2, and the anode forward current necessary for maintaining the conduction of the thyristor dimmer is provided by the LED constant current driver 1. When the thyristor dimmer is started in the next cycle, it can be started quickly, avoiding the problem that the screen light source of the mobile phone is blinking when the switch is switched, and the circuit is improved due to the fast conduction of the thyristor dimmer. The active power, that is, the realization circuit has high power factor value, easy to realize adjustment, and the circuit structure is simple, the required cost is low, and the stroboscopic component of the screen light source of the mobile phone is eliminated by the electrolytic capacitor, and the stroboscopic phenomenon can be avoided. And widening the working input voltage range, so that the LED light source continues to maintain the working state when the rectified bus voltage is less than the conduction voltage drop of the LED light source of the mobile phone screen, thereby improving the light effect intensity, and the electrolytic capacitor is due to the presence of the rectifier diode VD1. The loss of C1 during discharge is reduced, effectively improving efficiency. In addition, in the embodiment, the electrolytic capacitor C1 supplies power to the LED light source of the mobile phone screen when the bus voltage is less than the conduction voltage drop of the LED light source of the mobile phone screen. Due to the presence of the resistor R3, the electrolytic capacitor C1 extends the power supply time of the LED light source of the mobile phone screen, further Increased light efficiency.

The technical solutions provided by the embodiments of the present invention are described in detail above. The principles and implementation manners of the embodiments of the present invention are described in the following. The description of the foregoing embodiments is only applicable to help understand the embodiments of the present invention. At the same time, there will be changes in the specific embodiments and application scopes according to the embodiments of the present invention, and it should be noted that the above embodiments illustrate the present invention rather than the present invention. Limitations, and alternative embodiments may be devised by those skilled in the art without departing from the scope of the appended claims.

Claims

A mobile phone screen brightness control device, comprising:

Mobile phone screen light source, rectification processing module, thyristor dimmer, first constant current controller, second constant current controller, electrolytic capacitor, rectifier diode, first sampling resistor, second sampling resistor;

The rectification processing module is connected to an external power supply through the thyristor dimmer, and a normal phase output end of the rectification processing module is connected to one end of the first constant current controller and an anode of the rectifier diode, The negative phase output end of the rectification processing module is connected to the other end of the first constant current controller and grounded, and the control end A of the first constant current controller is grounded through the first sampling resistor and the second sampling resistor, a first sampling resistor and the second sampling resistor are connected by a point C, a cathode of the rectifier diode is connected to an anode of the screen light source of the mobile phone, and a cathode of the rectifier diode is also connected to a cathode of the electrolytic capacitor, the electrolysis a cathode of the capacitor is connected to the cathode of the screen light source of the mobile phone, and a cathode of the electrolytic capacitor is also connected to one end of the second constant current controller, and the other end of the second constant current controller is grounded, and the second constant current is The control terminal B of the controller is grounded through the second sampling resistor;

Wherein when the voltage at the control terminal A of the first constant current controller is greater than the voltage at point C, the first constant current controller is turned on to provide an anode forward required to maintain conduction of the thyristor dimmer Current; the electrolytic capacitor supplies power to the light source when the rectified bus voltage is less than the conduction voltage drop of the light source.
The device according to claim 1, further comprising: a third sampling resistor, one end of which is connected to the anode of the screen light source of the mobile phone, and the other end is connected to the cathode of the rectifier diode and the anode of the electrolytic capacitor.
The apparatus of claim 1 wherein said rectification processing module is a rectifier bridge stack.
A device according to any one of claims 1 to 3, further comprising an input control switch connected to an external power source.
A mobile phone screen brightness control device, comprising:

Mobile phone screen light source;

a thyristor dimmer for controlling the input current of the external power source to adjust the brightness of the screen light source of the mobile phone;

The rectification processing module is connected to the external power source through the thyristor dimmer, and is used for rectifying the input external power source;

a first constant current controller processing module coupled to the rectification processing module for providing an anode forward current required to maintain conduction of the thyristor dimmer;

a second constant current controller processing module is connected to the screen light source of the mobile phone for providing constant current driving for the screen light source of the mobile phone;

The electrolytic capacitor processing module has an electrolytic capacitor connected in parallel with the screen light source of the mobile phone, and is configured to supply power to the screen light source of the mobile phone when the rectified bus voltage is less than the conduction voltage drop of the screen light source of the mobile phone.
The device according to claim 5, wherein the electrolytic capacitor processing module comprises an electrolytic capacitor and a rectifier diode, an anode of the rectifier diode is connected to a positive phase output terminal of the rectifier processing module, and the rectifier diode is A cathode is coupled to the anode of the electrolytic capacitor and an anode of the screen source of the mobile phone.
The apparatus according to claim 6, wherein the first constant current controller processing module comprises: a first constant current controller and a first sampling resistor, and the second constant current controller processing module specifically includes a second constant current controller and a second sampling resistor, one end of the first constant current controller is connected to a positive phase output end of the rectification processing module and an anode of the rectifier diode, and the other end is grounded, and at the same time, The control terminal A of the first constant current controller is grounded through the first sampling resistor and the second sampling resistor, and the first sampling resistor and the second sampling resistor are connected by a point C, the second One end of the constant current controller is connected to the cathode of the screen light source of the mobile phone and the cathode of the electrolytic capacitor, and the other end is grounded, and the control terminal B of the second constant current controller is grounded through the second resistor.
The apparatus according to claim 7, further comprising: a third sampling resistor having one end connected to the cathode of the sorting diode and the anode of the electrolytic capacitor, and the other end connected to the anode of the screen light source of the mobile phone.
The apparatus of claim 5 wherein said rectification processing module is a rectifier bridge stack.
The apparatus of claim 5 further comprising: an input control switch coupled to the external power source.