TWI465152B - Led display device capable of balancing its current and method thereof - Google Patents

Description

LED display device capable of controlling current equalization and control method thereof

The invention relates to an LED display device, in particular to an LED display device capable of controlling current equalization and a control method thereof.

At present, LED (light-emitting diode) has been used as an energy-saving and environmentally-friendly light source for many lighting devices and display devices. Generally, for an LED display device, multiple LED tubes are often required. When the LED lamps are driven and displayed, the current of each LED tube is slightly different, resulting in inconsistent current flowing through each LED lamp. The brightness of the LED light is also different, which causes uneven display.

Therefore, it is necessary to provide an LED lamp driving device and method to solve the above problems.

In view of the above, an LED lamp driving device and method are provided for controlling current balancing in an LED lamp.

An LED display device capable of controlling current equalization includes a plurality of LED modules, a storage unit, a micro processing unit, a plurality of control switches, and a feedback voltage generating module. The micro processing unit includes a plurality of signal output ends, a feedback end, a correction trigger module, and a current correction module. The storage unit stores a standard voltage value. Feedback voltage generation module, and The feedback end is connected. Each control switch is connected in series with an LED module between a voltage terminal and the feedback voltage generating module, and the plurality of control switches are also respectively connected to the signal output terminals. The calibration triggering module is configured to generate a calibration trigger signal; when receiving the correction trigger signal, the current correction module controls a plurality of signal output terminals to sequentially output a pulse width modulation signal to a correspondingly connected control switch, so that the LED module sequentially In the working state, the feedback voltage generating module sequentially generates a feedback voltage to the feedback end and transmits it to the current correction module; after receiving the feedback voltage, the current correction module compares the feedback voltage with the standard voltage value in the storage unit. When inconsistent, the current correction module adjusts the pulse width modulation signal output by the corresponding signal output terminal according to the comparison result of the feedback voltage and the standard voltage value, thereby adjusting the current in the LED module.

A method for controlling current equalization of an LED display device, the LED display device comprising a plurality of LED modules, a storage unit, and a micro processing unit, wherein the storage unit stores a standard voltage value; the method for controlling current balancing of the LED display device comprises the steps of: starting correction Function; when the LED display device performs the startup or shutdown operation, sequentially controls each LED module to be in a working state; the operating current of the LED module is fed back to the micro processing unit in the form of a feedback voltage; the feedback voltage and the storage unit are The standard voltage value is compared; when the feedback voltage is inconsistent with the standard voltage value, the operating current of the LED module is adjusted according to the comparison result of the feedback voltage and the standard voltage value.

The LED display device and the control method for controlling current equalization of the invention can automatically correct the current of each LED module periodically, thereby equalizing the current flowing through the plurality of LED modules, so that the LED display device 1 emits light uniformly. .

1‧‧‧LED display device

10‧‧‧Microprocessing unit

L1, L2~Ln‧‧‧LED modules

K1, K2~Kn‧‧‧ control switch

20‧‧‧Feedback voltage generation module

PWM1, PWM2~PWMn‧‧‧ signal output

30‧‧‧storage unit

101‧‧‧Correction Trigger Module

102‧‧‧ Current Correction Module

FB‧‧‧ feedback end

Rs‧‧‧ Grounding resistor

T‧‧‧ connection node

D‧‧‧LED tube

Q1, Q1~Qn‧‧‧NPN transistor

Step S201‧‧‧Start correction function

Step S202‧‧‧ sequentially control each LED module to be in working state

Step S203‧‧‧feed back the operating current of the LED module to the micro processing unit in the form of feedback voltage

Step S204‧‧‧Comparison whether the feedback voltage is consistent with the standard voltage value

Step S205‧‧‧ Adjust the operating current of the LED module according to the comparison result

1 is a diagram showing the electric power of an LED display device capable of controlling current equalization according to a first embodiment of the present invention; Road map.

2 is a flow chart of a method for controlling current balancing of an LED display device in a first embodiment of the present invention.

Please refer to FIG. 1 , which is a circuit diagram of the LED display device 1 capable of controlling current equalization. The LED display device 1 includes a micro processing unit 10, a plurality of LED modules L1~Ln (n>=2), a plurality of control switches K1~Kn (n>=2), and a feedback voltage generating module 20, the micro processing unit 10 includes a plurality of signal outputs PWM1~PWMn and a feedback end FB. Wherein, each LED module is connected in series with a control switch between the voltage terminal Vcc and the feedback voltage generating module 20, and the signal output terminals PWM1~PWMn are respectively connected with the control switches K1~Kn one-to-one for output pulse width. The modulation signal controls the on and off of the corresponding control switch, thereby controlling the LED module to work or not. The feedback voltage generating module 20 is connected to the feedback end FB for generating a feedback voltage to the feedback end FB when the LED module is in operation, and the feedback voltage is a reflection of the actual working current of the LED module. The LED display device 1 further includes a storage unit 30 for storing a standard voltage value. The standard voltage value is a reflection of the standard operating current of the LED modules L1~Ln.

The micro processing unit 10 further includes a calibration trigger module 101 and a current correction module 102. The calibration trigger module 101 is configured to generate a correction trigger signal to initiate a correction function, wherein the calibration trigger module 101 can periodically generate the correction trigger signal according to a system default or a user-set correction period, for example, every other one. A correction trigger is generated for the week or month. In other embodiments, the calibration trigger module 101 can also generate a correction trigger signal according to a period in which the LED display device 1 is turned on and off. For example, each time the LED display device 1 is turned on or off, the calibration trigger module 101 generates This correction trigger signal. In other embodiments, the LED display device The 1 can also include a correction function key (not shown), and the user can generate a control command through the correction function key to trigger the calibration trigger module 101 to generate the correction trigger signal. After receiving the correction trigger signal, the current correction module 102 sequentially controls an LED module to be in an active state, that is, the current correction module 102 controls the signal output terminals PWM1~PWMn to output a pulse width modulation signal to the corresponding control switch K1~Kn. The LED modules L1~Ln are sequentially in operation, and the feedback voltage generating module 20 sequentially generates a feedback voltage reflecting the operating current of the LED module in the working state to the feedback end FB, and transmits the feedback voltage to the current correction module 102. In this embodiment, at the same time, the current correcting module 102 only controls one signal output terminal to output a pulse width modulation signal, and the other signal output terminals do not output a pulse width modulation signal. Therefore, at the same time, there is only one LED mode. The group is in working condition while the other LED modules are not working. After receiving the feedback voltage, the current correction module 102 compares the feedback voltage with the standard voltage value in the storage unit 30. When not, the output of the corresponding signal output terminal is adjusted according to the comparison result of the feedback voltage and the standard voltage value. The pulse width modulation signal adjusts the operating current of the LED module.

In this embodiment, the pulse width modulation signal initially outputted by the signal output terminals PWM1~PWMn is used to control the current of the LED modules L1~Ln as a standard current value, and some LED modules are caused by the unevenness of the material of the LED module. The actual current is not the standard current value. The current correction module 102 adjusts the pulse width modulation signal outputted by the signal output terminal according to the comparison result of the feedback voltage and the standard voltage value. If the feedback voltage is higher than the standard voltage value, the LED is indicated. The actual current value of the module is higher than the standard current value, thereby adjusting the pulse width modulation signal outputted by the signal output terminal, and controlling the operating current of the LED module to be lowered until the actual current of the LED module is adjusted to be consistent with the standard current value. . Conversely, if the feedback voltage is lower than the standard voltage value, the actual current value of the LED module is lower than the standard current value, thereby adjusting the pulse width modulation signal outputted by the signal output terminal, and controlling The operating current of the LED module is adjusted until the actual current of the LED module is adjusted to be consistent with the standard current value.

The current correction module 102 adjusts the pulse width modulation signal outputted by the corresponding signal output terminal to adjust the duty ratio of the pulse width modulation signal. Because the duty ratio of the pulse width modulation signal is different, the time for controlling the on and off of the switch is different, thereby The current flowing through the LED module also changes accordingly. Wherein, the greater the duty ratio of the pulse width modulation signal outputted by the signal output terminal, the longer the control switch conduction time is, the larger the operating current of the LED module is.

In the present embodiment, the LED modules L1 L Ln each include a plurality of LED tubes D connected in series. In FIG. 1 , the number of the LED tubes D is two. In other embodiments, the LED tubes D are The number can be any number of three or four. The plurality of control switches K1~Kn each include a control terminal (not labeled), a first conductive terminal (not labeled), and a second conductive terminal (not labeled), and the control terminals of the plurality of control switches K1~Kn are respectively associated with signals The output terminals PWM1~PWMn are connected, and the first conductive ends are respectively connected to the LED modules L1~Ln. The feedback voltage generating module 20 is a grounding resistor Rs, and one end of the grounding resistor Rs away from the grounding point is connected with the feedback end FB to form a connecting node T, and the connecting node T is simultaneously connected with the second conducting ends of the plurality of control switches K1 to Kn. connection. In this embodiment, the plurality of control switches K1 - Kn are NPN transistors Q1 - Qn , and the control terminal, the first conductive terminal and the second conductive terminal respectively correspond to the base, the emitter and the collector of the NPN transistor.

When the calibration trigger module 101 arrives at a calibration period or the user presses the correction function button, the correction trigger signal is generated. After receiving the correction trigger signal, the current correction module 102 sequentially outputs a pulse through the signal output terminals PWM1~PWMn. The wide modulation signal is sent to the corresponding control switches K1~Kn, so that the LED modules L1~Ln are in the working state in sequence. The LED module currently in operation, the control switch receiving the pulse width modulation signal, and the grounding resistor Rs form a current loop, so that the grounding resistance Rs is away from the grounding point One end of the connection node T generates a voltage, that is, a feedback voltage, and the feedback terminal FB receives the feedback voltage and transmits it to the current correction module 102. After receiving the feedback voltage, the current correction module 102 stores the feedback voltage and the storage unit 30. The standard voltage values are compared. When they are inconsistent, the pulse width modulation signal outputted by the corresponding signal output terminal is adjusted according to the comparison result of the feedback voltage and the standard voltage value, thereby adjusting the current in the currently operating LED module.

For example, when the current correction module 102 outputs a pulse width modulation signal to the control switch K2 (NPN transistor Q2) such that the control switch K2 is turned on, the branch of the LED module L2 is turned on, and the LED module L2 and the grounding resistor Rs are formed. a current loop, the voltage terminal Vcc provides a current to the current loop, the current is the operating current of the LED module L2, the operating current flows through the grounding resistor Rs such that the remote terminal of the grounding resistor Rs, that is, the connecting node T has a voltage The voltage is a feedback voltage that reflects the operating current of the LED module L2. After receiving the feedback voltage, the current correction module 102 compares the feedback voltage with the standard voltage value in the storage unit 30. When not, the output of the corresponding signal output terminal is adjusted according to the comparison result of the feedback voltage and the standard voltage value. The pulse width modulation signal adjusts the current in the currently operating LED module.

Please refer to FIG. 2 , which is a flow chart of a method for controlling current balancing of the LED display device 1 according to the present invention. First, the correction trigger module 101 generates a correction trigger signal when a trigger period comes or the user presses the correction function key, and activates the correction function (S201). After receiving the correction trigger signal, the current correction module 102 sequentially controls the operation of the LED modules L1~Ln, that is, the current correction module 102 controls the signal output terminals PWM1~PWMn to respectively output the pulse width modulation signals to the control switches K1~Kn, and is turned on. The branch of the LED module L1 is such that the LED modules L1 to Ln are sequentially in operation (S202). The feedback voltage generating module 20 sequentially feeds the operating currents of the LED modules L1 LLn to the feedback end FB of the micro processing unit 10, That is, the feedback voltage generating module 20 sequentially generates a feedback voltage reflecting the operating current of the LED module in the working state to the feedback end FB (S203). The current correction module 102 compares the feedback voltage with a standard voltage value in the storage unit 30, and determines whether the feedback voltage matches the standard voltage value in the storage unit (S204). When the current correction module 102 determines that the feedback voltage does not match the standard voltage value, the operating current of the LED module is adjusted according to the comparison result of the feedback voltage and the standard voltage value, that is, when the feedback voltage is less than the standard voltage value, the current correction module 102 The duty ratio of the pulse width modulation signal outputted by the corresponding signal output terminal is increased to increase the operating current of the LED module, and the current correction module 102 outputs the corresponding signal output terminal when the feedback voltage is greater than the standard voltage value. The duty cycle of the pulse width modulation signal is lowered to reduce the operating current of the LED module (S205).

Therefore, the LED display device and the control method for controlling current equalization of the present invention can automatically correct the current of each LED module periodically, thereby equalizing the current flowing through the LED modules L1 to Ln, so that the LED display device 1 uniform illumination.

Step S201‧‧‧Start correction function

Step S202‧‧‧ sequentially control each LED module to be in working state

Step S203‧‧‧feed back the operating current of the LED module to the micro processing unit in the form of feedback voltage

Step S204‧‧‧Comparison whether the feedback voltage is consistent with the standard voltage value

Step S205‧‧‧ Adjust the operating current of the LED module according to the comparison result

Claims (10)

An LED display device capable of controlling current equalization, comprising a plurality of LED modules, wherein the controllable current equalization LED display device further comprises: a storage unit storing a standard voltage value; and a micro processing unit comprising: a plurality of signal outputs And a feedback end; a feedback voltage generating module connected to the feedback end; and a plurality of control switches, each control switch being connected in series with an LED module between a voltage terminal and the feedback voltage generating module, The plurality of control switches are also respectively connected to the plurality of signal output terminals; the micro processing unit further includes a correction trigger module and a current correction module, wherein the correction trigger module is configured to generate a correction trigger signal; the current correction module receives the After the correction trigger signal, the control signal output terminal sequentially outputs a pulse width modulation signal to the corresponding connected control switch, so that the LED module is in the working state in turn, and the feedback voltage generation module generates an LED module reflecting the working state. The feedback current of the working current is sent to the feedback end and transmitted to the current correction module; the current correction module receives After the voltage is fed back, the feedback voltage is compared with the standard voltage value in the storage unit. When not in agreement, the current correction module adjusts the pulse width modulation outputted by the corresponding signal output terminal according to the comparison result of the feedback voltage and the standard voltage value. The duty cycle of the signal to regulate the current in the LED module. The controllable current equalization LED display device of claim 1, wherein the calibration trigger module periodically generates the correction trigger signal according to a system default or a user-set calibration period. The controllable current equalization LED display device of claim 2, wherein the controllable current equalization LED display device further comprises a correction function button for generating a control command to trigger the calibration trigger module to generate the Correct the trigger signal. The LED display device capable of controlling current equalization according to claim 1, wherein the current correction module controls the output of the pulse width modulation signal outputted by the corresponding signal output terminal when the feedback voltage is less than the standard voltage value. The air ratio increases the operating current of the corresponding LED module. When the feedback voltage is greater than the standard voltage value, the current correction module controls to decrease the duty ratio of the pulse width modulation signal outputted by the corresponding signal output terminal, thereby reducing Small corresponding LED module operating current. The controllable current equalization LED display device of claim 1, wherein each of the LED modules comprises a plurality of LED tubes connected in series. The controllable current equalization LED display device of claim 1, wherein each control switch comprises a control end, a first conductive end and a second conductive end, and the control ends of each control switch respectively The first conductive terminals are connected to the plurality of LED modules one by one. The controllable current equalization LED display device according to claim 6, wherein the control switch is an NPN transistor, and the control end, the first conductive end and the second conductive end respectively correspond to a base of the NPN transistor. , emitter and collector. The controllable current equalization LED display device according to claim 6, wherein the feedback voltage generating module is a grounding resistor, the grounding resistance is away from the grounding point and the feedback end, and the second conducting of the plurality of control switches The terminal is connected, and the current correction module receives the current correction signal, and controls a signal output terminal to output a pulse width modulation signal to the corresponding control switch, so that the LED module in series with the control switch is in an active state, the LED module The control switch and the grounding resistor form a current loop such that the grounding resistor is remote from the ground point to generate the feedback voltage. A method for controlling current balance of an LED display device, the LED display device comprising a plurality of LED modes a group, a plurality of control switches, a storage unit, and a micro processing unit, wherein the storage unit stores a standard voltage value; each control switch is connected in series with an LED module between a voltage terminal and the feedback voltage generating module, and the improvement is The method for controlling current balancing of the LED display device comprises the steps of: starting a correction function; sequentially controlling each LED module to be in a working state by sequentially outputting a pulse width modulation signal to a control switch connected to the plurality of LED modules; The working current of the module is fed back to the micro processing unit in the form of a feedback voltage; whether the feedback voltage is consistent with the standard voltage value in the storage unit; when the feedback voltage is inconsistent with the standard voltage value, the comparison result is based on the feedback voltage and the standard voltage value. The duty cycle of the output pulse width modulation signal is adjusted to adjust the operating current of the LED module. The method for controlling current equalization of an LED display device according to claim 9, wherein the step of "starting the correction function" comprises: periodically starting the correction function according to a system default or a user-set correction period.