CN102511200A - LED Array Driver Circuit - Google Patents

Abstract

The invention relates to a light emitting diode array driving circuit, which ensures that each group of LED arrays can constantly maintain average power within a large-range input voltage range, sequentially extinguishes the LED arrays according to a lighting sequence, distributes lighting time of each group of LED arrays, and enables loads borne by LEDs to be equal, thereby ensuring the stability of the LED driving field and prolonging the service life of the LEDs. The light emitting diode array driving circuit structure of the invention comprises: a voltage control part for controlling the rising and falling of the input voltage of the power supply subjected to the full-wave rectification through a bridge diode; the plurality of LED devices are connected in series to form a group, more than 2 n LED arrays of each group are connected in series, and the adjacent LEDs of each group respectively belong to the LED arrays of each different group; open switches connected in series to the respective groups of the LED arrays in order to turn on the respective groups of the LED arrays in a connection order as a voltage of the voltage control unit increases; closed switches connected in parallel to the respective groups of the LED arrays, respectively, for turning off the respective groups of the LED arrays in the order of lighting as the voltage of the voltage control part decreases; and a switch control part which is respectively connected with the n-1 open switches, the n-1 closed switches and the voltage control part and controls the opening and closing actions of the switches along with the voltage rise and fall of the voltage control part.

Description

LED Array Driver Circuit

technical field

The invention relates to a light emitting diode array driving circuit. A light emitting diode array driving circuit that sequentially controls on/off driving of LEDs combined in series in a lighting device using the light emitting diode driving circuit.

Background technique

In the process of current flowing into the LED and emitting light, there are many ways to drive the LED. Such as: drive by voltage or current, linear (LINEAR) or switching (SWITCHING) related to switching (SWITCHING) or not, etc.

The commonly used method is to use the LED driving method of series resistors. A voltage drive method in which the current flowing to the LED is affected by the connected voltage (Vi) and the value of the resistor (R) connected in series with the LED.

The above method has the simplest structure and is the most commonly used structure. Although the circuit is simple, it cannot control the current according to the change of the input voltage, so it has the disadvantage of low power efficiency.

The LED driving method using an active device is a method using a variable voltage source or a current source in order to control the current in the LED device. The basic principle is similar to that of LED drive using series resistors, but the voltage or current is adjusted linearly or commutatively.

Another way, as shown in Figure 1, is a current-controlled LED driving method using a series voltage control regulator (Regulator).

It is a structure that adjusts the LED current through a transistor (TR) and an operational amplifier. The current in the LED is regulated by feeding back the voltage across the sense resistor (RSENSE).

The circuit structure is relatively simple, and the current passing through the LED can be adjusted more stably. However, when the voltage between the collector and emitter of the transistor (TR) is lowered in order to control the current flowing through the LED, the electrical efficiency is lowered, which is a disadvantage.

In addition, as shown in Figure 2, there is a current-controlled LED drive method using switching devices.

According to the increase and decrease of the AC input voltage, each LED group effectively controls the peak current (Peak Current) through the exchange part based on the standard voltage. The advantage is that it has the characteristics of high efficiency, high power factor, and low harmonic distortion in a wide range of input voltage range.

In the above driving mode, in the series LED array groups G1, G2, G3, G4, as the AC input voltage rises, G1, G2, G3, G4 light up sequentially; as the AC input voltage decreases, G4, G3, G2 and G1 are turned off in turn, and then the load on the LED of G1 increases, acting as electrical stress.

Therefore, there is a need for an LED driving method that distributes the load on the LEDs by allocating the lighting time of each group of LED arrays.

Contents of the invention

Problems to be Solved by the Invention

The present invention is proposed in view of the above existing problems, and the present invention provides a LED array driving circuit. Adopt the driving method of changing the LED circuit connection according to the input voltage, through the voltage/current monitoring part, the LED arrays of each group are turned off in the order of lighting.

Problem solution

In order to achieve the above object, the present invention relates to a light emitting diode array driving circuit. It includes a voltage control unit that controls the rise and fall of the full-wave rectified power supply input voltage through a bridge diode; a plurality of LED devices are connected in series to form a group, and more than two LED arrays of N above-mentioned groups are connected in series to form Each adjacent group of LEDs belongs to each group of LED arrays of each group; as the voltage of the voltage control part rises, each group of LED arrays is sequentially lit according to the order of connection, and the open type connected in series with each group of LED arrays switch; as the voltage of the voltage control part decreases, each group of LED arrays is turned off sequentially according to the order of lighting, and a closed switch connected in parallel with each group of LED arrays; respectively connected to the above n-1 open switches and The n-1 enclosed switches are connected to the voltage control unit, and the switch control unit controls the opening and closing operations of these switches according to the voltage rise and fall of the voltage control unit.

In the present invention, the open switches are composed of n-1 open switches, and the first group to n-1 groups are respectively connected in series with each group of LED arrays. When the voltage is connected, the LED array of the first group is in the state of lighting up, obeying the control command issued by the switch control part according to the voltage increase of the voltage supply part, from the first open switch to the mth open switch - m is more than 2 , less than n-1-turn off sequentially, and the LED arrays corresponding to the m+1th group of the mth open switch are sequentially lit.

In the present invention, the closed switch is composed of n-1 closed switches, the first group to the n-1th group are respectively connected in series with each group of LED arrays, and the LED array points of the first group to the mth group In the bright state, listen to the control command issued by the switch control part according to the voltage drop of the voltage supply part, from the first closed switch to the first closed switch - 1 is more than 2, m is less - turn ON in sequence, corresponding The LED array of the first group of the first enclosed switch is extinguished.

The open switch and the closed switch in the present invention are composed of transistors, the switch control part is connected to the transistor base (Transistor Base), and the transistors are turned on and insulated according to the voltage supplied by the switch control part.

Invention effect

The light-emitting diode array drive circuit invented according to the solution to the above problems ensures that each group of LED arrays maintains a constant average power within a wide range of input voltage ranges, and turns off sequentially according to the lighting sequence, and distributes the lighting time of each group of LED arrays , so that the load on the LED is equalized, so as to ensure the stability of the LED driving field and prolong the life of the LED.

Brief description of the drawings

Fig. 1 shows a circuit diagram of a current-controlled LED drive using an existing series voltage control regulator;

Fig. 2 shows the circuit diagram of the current control type LED driver using the existing switching equipment;

Fig. 3 shows the overall circuit diagram of the first embodiment of the LED array driving circuit;

FIG. 4 shows the overall circuit diagram of the second embodiment of the LED array driving circuit.

The accompanying symbols are explained as follows:

10, 110: bridge diode (Bridge Diode); 20, 120: current limiting part; 30, 130: voltage control part; 40, 140: switch control part; 50, 150: each LED array; 51, 151: first Group; 52, 152: second group; 53, 153: third group; 60: open switch; 61: first open switch; 62: second open switch; 70: closed switch; 71: first Closed switch; 72: second closed switch; 160: open-loop transistor; 161: first open-loop transistor; 162: second open-loop transistor; 170: closed-loop transistor; 171: first closed-loop transistor; 172: second closed-loop transistor.

Detailed ways

Embodiments of the LED array driving circuit related to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 3 shows the overall circuit diagram of the first embodiment of the LED array driving circuit.

As shown in FIG. 3 , the present invention is composed of power supply 11 , bridge diode 10 , LED arrays 50 , open switch 60 , closed switch 70 , switch control unit 40 , current limiting unit 20 , and voltage control unit 30 .

The bridge diodes 10, when AC power 11 is supplied to the circuit, cause the power to be full-wave rectified.

The voltage control unit 30 is a module that controls the rise and fall of the AC input voltage, and transmits the voltage value to the switch control unit 40 that will be described below. The current limiting unit 20 is a block that ensures constant input current and output current.

The groups of LED arrays 50 are connected in series to form a group of multiple LED devices, and the groups of LED arrays 50 are reconnected in series, and each adjacent group of LEDs belongs to each group.

In the example circuit diagram shown in FIG. 3 , each group of LED arrays 50 is formed by connecting the first group 51, the second group 52, and the third group 53, but according to an embodiment of the present invention, each group of LED arrays 50 can be composed of 2 or more groups of connections.

That is, the minimum number of LED array groups in the present invention is more than 2, if the number of groups is n, the number of lit groups may be m out of n, and the m groups that are lit are more than 1, n the following.

There are n-1 related open switches and closed switches respectively. According to the Off state of the mth open switch, the LED array to the m+1th group is lit. In the entire n group, when the mth group is lit, according to the On state of the first closed switch, to the One set of LED arrays goes out.

The open switch 60 is a switch that lights up each group of LED arrays 50 connected in series in sequence. Under the state that the LED array of the first group 51 is lighted, the first open switch 61 of the second group 52 LED array is lighted; Turn on the second open switch 62 of the third group 53 of the LED array.

The open switches 60 are respectively connected in series with each group of LED arrays 50 and the switch control unit 40 . Specifically, the first open switch 61 is connected in series with the first group 51 and the switch control unit 40 respectively. When the first open switch 61 is ON, only the first group of LED arrays are lit. With the first open switch 61 OFF, the first group 51 and the second group 52 of the LED arrays will light up.

Similarly, the second open switch 62 is connected in series with the second group 52 and the switch control part 40 respectively, when the second open switch 62 is ON, only the first group 51 and the second group 52 LED arrays are lit. state, along with the OFF of the second open switch 62, there will be current passing through, and the LED arrays of the first group 51, the second group 52, and the third group 53 will be lit.

The enclosed switch 70 is a switch that turns off the series-connected LED arrays 50 in the order of lighting. Include under the state that all groups of LED arrays 50 are lighted, extinguish the first closed switch 71 of the first group 51 LED arrays; A second enclosed switch 72 of the group 52 LED array.

For this reason, the enclosed switches 70 are respectively connected in parallel with each group of LED arrays 50 , and are respectively connected in series with the switch control part 40 .

Specifically, the first enclosed switch 71 is connected in parallel with the first group 51 and connected in series with the switch control unit 40 . In the state that the second group of LED arrays including all groups of LED arrays 50 are lighted, along with the ON of the first closed switch 71, the first group of 51 LED arrays will be extinguished.

Likewise, the second enclosed switch 72 is connected in parallel with the second group 52 and connected in series with the switch control unit 40 . The ON of the first enclosed switch 71, only under the state that the first group of 51 LED arrays are extinguished, along with the ON of the second enclosed switch 72, the second group of 52 LED arrays will be extinguished.

The switch control unit 40 is connected in series with the open switch 60 and the closed switch 70 respectively, and as the voltage of the voltage control unit 30 rises and falls, the switching commands for controlling the actions of each switch are transmitted to the open switch 60 and enclosed switch 70.

Then, according to the circuit configuration, when the power source 11 is connected to the circuit, the power source is full-wave rectified while passing through the bridge diode 10 and transmitted to the current limiting section 20 .

The current limiting unit 20 keeps the input current consistent with the output current when the voltage rises and falls under the action of the voltage control unit 30 .

The voltage control unit 30 transmits a corresponding voltage value to the switch control unit 40 , and the switch control unit 40 will turn on the first open switch 61 according to the initial low voltage.

At this time, all the enclosed switches 70 are in the closed state.

When the voltage is transmitted to the LED array of the first group 51, the first group 51 emits light, which is transmitted to the switch control unit 40 through the first open switch 61 in the ON state.

In this state, when the voltage increases under the action of the voltage control unit 30 , the switch control unit 40 will close the first open switch 61 and open the second open switch 62 .

When the voltage is transmitted to the first group 51 of the LED array, because the first open switch 61 is in a closed state, the voltage cannot be transmitted to the first open switch 61. After the first group 51, the second group 52 The light is transmitted to the switch control unit 40 through the second open switch 62 in the open state.

When the voltage increases under the action of the voltage control unit 30 , the switch control unit 40 will close the first open switch 61 and the second open switch 62 .

When the voltage is transmitted to the first group 51 LED array, because the first open switch 61 and the second open switch 62 are closed, the voltage cannot be transmitted to the second open switch 61, following the first group 51 , the second group 52 and the third group 53 emit light in sequence.

As above, according to the connection sequence of each group of LED arrays 50, when all the light emitting diodes are lit, when the voltage drops under the action of the voltage control part 30, the switch control part 40 will open the first closed switch 71 to turn off the light. The first set of 51 initially lit.

When the first open switch 61 is closed, the voltage cannot pass through the first group 51, but passes through the first closed switch 71 in the ON state, and flows to the LED arrays and switches above the second group 52 control unit 40 .

In this state, when the voltage control unit 30 further reduces the voltage, the switch control unit 40 will turn on the second closed switch 72 , and turn off the second group 52 after the first group 51 .

Therefore, in the state where the first open switch 61 and the second open switch 62 are closed, the voltage cannot pass through the first group 51 and the second group 52, but passes through the first group 51 and the second group 52 in the ON state. The enclosed switch 71 and the second enclosed switch 72 flow to the third group 53 of LED arrays and the switch control unit 40 .

FIG. 4 shows the overall circuit diagram of the second embodiment of the LED array driving circuit.

As shown in the figure, the present invention includes a power supply 111 , a bridge diode 110 , each group of LED arrays 150 , an open-loop transistor 160 , a closed-loop transistor 170 , a transistor control unit 140 , a current limiting unit 120 , and a voltage control unit 130 .

The bridge diode 110 allows the power to be full-wave rectified when the AC power 111 is supplied to the circuit.

The voltage control unit 130 is a module that controls the increase and decrease of the AC input voltage, and transmits the voltage value to the transistor control unit 140 described below; the current limiting unit 120 is a module that keeps the input current and the output current constant.

Each group of LED arrays 150 is formed by connecting multiple LED devices in series into one group, and reconnecting each group of LED arrays 150 , and each adjacent group of LEDs belongs to each group.

In the exemplary circuit diagram shown in FIG. 4 , each group of LED arrays 150 is connected to three groups of the first group 151, the second group 152, and the third group 153, but according to an embodiment of the present invention, each group of LED arrays 150 can be connected to 2 groups. Group above connections.

The open-loop transistor 160 is a PNP transistor that lights up each group of LED arrays 150 connected in series according to the sequence of connection. Include in the state that the LED array of the first group 151 is lit, light the first open-loop transistor 161 of the second group 152 LED array; The second open-loop transistor 162 of the third group 153 of the LED array.

The open-loop transistors 160 are respectively connected in series with each group of LED arrays 150 and the transistor control unit 140 . More specifically, the first open-loop transistor 161 is connected in series with the first group 151 and the emitter, and at the same time connected in series with the base (Base) of the transistor control part 140 to connect the voltage to the first open-loop transistor When the base of 161 is turned on, only the first group of 151 LED arrays are lit; the voltage is not connected to the first open-loop transistor 161 base, when it cannot be turned on, the first group of 151 and the second group of 152 LEDs are lit array.

Similarly, the second open-loop transistor 162 is connected in series with the second group 152 and the transistor control unit 140 respectively, the second open-loop transistor 162 is turned on, only the first group 151 and the second group 152 LED array points In the bright state, the LED arrays of the first group 151 , the second group 152 and the third group 153 are turned on when no voltage is connected to the base in order to make the second open-loop transistor 162 non-conductive.

The closed-loop transistor 170 is a PNP transistor that turns off each group of LED arrays 150 connected in series according to the order of lighting. Including under the state that all groups of LED arrays 150 are lighted, turn off the first closed-loop transistor 171 of the first group 151 LED array; The second closed-loop transistor 172 of two groups of 152 LED arrays.

To this end, the closed-loop transistors 170 are respectively connected in parallel with each group of LED arrays 150 and connected in series with the transistor control part 140 .

Specifically, the first closed-loop transistor 171 is connected in parallel with the first group 151 and the emitter, the transistor control unit 140 is connected in series with the base, and the first closed-loop transistor 171 is connected in series with the collector.

Thus, in the state where the second group of LED arrays 150 are turned on, including the state where all the groups of LED arrays 150 are turned on, when the voltage is supplied to the emitter of the first closed-loop transistor 171 and turned on, the first Group 151 of the LED array will be off and the LED arrays from the second group 152 onwards will remain on.

Likewise, the second closed-loop transistor 172 is connected in parallel with the second group 152 and the emitter, the transistor control unit 140 is connected in series with the base, and the second closed-loop transistor 172 is connected in series with the collector (Collector).

The first closed-loop transistor 171 is turned on, only when the first group 151 LED arrays are turned off, the second closed-loop transistor 172 is turned on on the same principle, and the second group 152 LED arrays will be turned off.

The transistor control part 140 is connected in series with the open-loop transistor 160 and the closed-loop transistor 170 respectively, so as the voltage of the voltage control part 130 rises and falls, the voltage is supplied or cut off to the open-loop transistor 160 and the closed-loop transistor 170, thereby Control whether each transistor is turned on or not.

In the above circuit structure, when the power supply 111 is connected to the circuit, the power supply is full-wave rectified and transmitted to the current limiting unit 120 when the power supply passes through the bridge diode 110 .

The current limiting unit 120 keeps the input current consistent with the output current when the voltage rises and falls under the action of the voltage control unit 130 .

The voltage control part 130 transmits a corresponding voltage value to the transistor control part 140, and according to the initial low voltage, the transistor control part 140 supplies a voltage to the base of the first open-loop transistor 161 and realizes conduction.

At this time, the closed-loop transistors 170 are all in isolation state.

When the voltage is transmitted to the LED array of the first group 151, the first group 151 will emit light, and the voltage is transmitted to the transistor control unit 140 through the first open-loop transistor 161 in the conduction state.

In this state, when the voltage increases under the action of the voltage control unit 130 , the transistor control unit 140 will isolate the first open-loop transistor 161 and turn on the second open-loop transistor 162 .

When the voltage is transmitted to the first group 151 LED array, because the first open-loop transistor 161 is in an insulated state, the voltage cannot be transmitted to the first open-loop transistor 161. After the first group 151, the second group 152 The light is transmitted to the transistor control unit 140 through the second open-loop transistor 162 in the on state.

When the voltage rises under the action of the voltage control unit 130 , the transistor control unit 140 will turn on the first open-loop transistor 161 and the second open-loop transistor 162 .

When the voltage is transmitted to the LED array of the first group 151, since the first open-loop transistor 161 and the second open-loop transistor 162 are in an insulated state, the voltage cannot be transmitted to the second open-loop transistor 161, following the first group After 151, the second group 152 and the third group 153 are turned on to emit light.

As above, according to the connection sequence of each group of LED arrays 150, when all the light-emitting diodes are lit, when the voltage drops under the action of the voltage control unit 130, the transistor control unit 140 supplies the emitter of the first closed-loop transistor 171 with The voltage is turned on, extinguishing the first group 151 which was initially lit.

When the first open-loop transistor 161 is turned on, the voltage cannot pass through the first group 151, but flows to the LED arrays above the second group 152 through the first closed-loop transistor 171 in the turned-on state. and the transistor control unit 140 .

In this state, when the voltage control part 130 further reduces the voltage, the transistor control part 140 will supply voltage to the emitter of the second closed-loop transistor 172 and realize conduction, and after the first group 151, turn off the second Group 152.

Thus, in the state where the first open-loop transistor 161 and the second open-loop transistor 162 are insulated, the voltage cannot pass through the first group 151 and the second group 152, but passes through the on-state The first closed-loop transistor 171 and the second closed-loop transistor 172 flow to the third group 153 of the LED array and the transistor control unit 140.

Claims (4)

1. light emitting diode matrix drive circuit, said light emitting diode matrix drive circuit comprises:

Control the voltage control division that is raise and reduce by the input voltage of the power supply of full-wave rectification through the bridge diode; The series connection of plural number LED device is a group, respectively organizes the led array series connection for the n more than 2 simultaneously, make adjacent respectively organize LED belong to respectively each not on the same group respectively organize led array; Along with the voltage of said voltage control division raises, make and respectively organize led array and light the open switch of connecting with each group led array respectively according to the order that connects successively; Along with the voltage of said voltage control division reduces, make and respectively organize led array order extinguishes successively according to lighting, respectively with the parallelly connected enclosed switch of each group led array; N-1 open switch links to each other with n-1 enclosed switch and voltage control division separately, the switch control part of control switch on-off action along with the voltage up-down of said voltage control division.

2. light emitting diode matrix drive circuit according to claim 1, wherein, said open switch is made up of n-1 open switch, organizes led array respectively to the n-1 group for first group and connects with each; Connect voltage; Under the state that first group led array is lighted; Accept the control command that the switch control part raises and sends according to the voltage of voltage supply department; Is more than 2 from first open switch to m open switch-m, below the n-1-extinguishing successively in order, the led array of the m+1 group of corresponding said m open switch is lighted successively.

3. light emitting diode matrix drive circuit according to claim 2; Wherein, Said enclosed switch is made up of n-1 enclosed switch, organizes led array respectively to the n-1 group for first group and connects, under the state that said first group of led array of organizing to m lighted with each; Accept the switch control part and reduce the control command of sending according to the voltage of voltage supply department; Is more than 2 from first enclosed switch to first enclosed switch-1, below the m-to light successively in order, first group led array of corresponding said first enclosed switch extinguishes.

4. light emitting diode matrix drive circuit according to claim 1; Wherein, Said open switch and enclosed switch are made up of transistor, and said switch control part is connected with said transistor base, come conducting and insulate said transistor according to the voltage of switch control part supply.

Images