CN204652754U - For constant-current control circuit and this display unit of LED display - Google Patents

Abstract

A kind of wiring less, consume energy little and be suitable for high voltage low current drive the constant-current control circuit for LED display and this display unit.Comprise the LED illuminating module be made up of at least two LED luminescence units and at least one constant flow module, all LED luminescence units are connected in a series arrangement with constant flow module, on each LED luminescence unit and be connected to one by pwm signal control this LED luminescence unit open or close switch control module, be also provided with in described constant flow module control its break-make control module be turned on or off; The all switch control modules of this break-make control module in this LED illuminating module send the pwm signal disconnecting this constant flow module when receiving the pwm signal of closing corresponding LED luminescence unit.The LED illuminating module length be made up of it can reach 20 meters, and the LED display line consumption be made up of it is little, wire material is few, wiring is neat simple, and installation effectiveness is high.

Description

Constant current control circuit for LED display device and the display device

technical field

The utility model relates to a control circuit of an LED display device, in particular to a control circuit widely used in LED display screens, intelligent LED full-color lamp groups and decorative lamp strings composed thereof.

Background technique

Existing LED display screens and full-color LED light sets (hereinafter referred to as LED loads) are composed of several LED light-emitting modules. Usually, these light-emitting modules are driven by low voltage and high current, and their terminal voltage is mostly 5V. Its connection structure is: multiple LED light-emitting modules are connected in parallel between the 5V terminal voltage, each LED light-emitting module is a single LED lamp bead or a group of R, G, B three-color LED lamp beads connected in parallel (see figure 1 and 9).

These LED light-emitting modules are connected in parallel in terms of circuit connection structure, but in practical applications, the LED loads formed by them are arranged in series, and two adjacent LED light-emitting modules to be connected in parallel In the one-dimensional direction, the LED loads with a large area or a long line segment are finally formed by being arranged in a front-to-back adjacent arrangement. This connection structure makes the wires used by the latter LED lighting module connected to the same power supply terminal longer than the wires used by the previous LED lighting module.

There is following deficiency in above-mentioned structure:

1) Due to the adoption of low-voltage high-current drive and the connection structure of the LED load composed of several sets of LED light-emitting modules connected in parallel, and in order to avoid unsafe hazards caused by excessively high drive currents, the number of power supplies used will increase , Thus, the investment cost is too high (the longest wire of each group of LED lighting modules is about 5 meters).

2) When connecting the LED lighting module to the power connection terminal, if a thin-diameter connecting wire is used, the temperature will be high and the line loss will be high due to excessive current; if the current wiring on the PCB board is designed to be wide If some or thicker diameter connecting wires are used, the consumables will increase and the cost will increase.

3) The amount of wiring is large. Since all LED lighting modules are connected in parallel, in order to form the LED load with a large area or a long line segment, the length of the wires used in different LED lighting modules connected to the same power supply connection end will be different, and the distance from the power supply The wire used by the LED light-emitting module closer to the connection end is shorter, and the wire used by the LED light-emitting module farther from the power supply connection end will be very long, thus resulting in increased wire consumption, increased cost, and line loss (ie The current loss flowing through the wire) increases.

4) The large difference in the length of the wires used leads to messy and complicated wiring, long engineering installation time, low efficiency, and high labor input costs.

Utility model content

The technical problem to be solved by the utility model is to provide a constant current control circuit for an LED display device which has less wiring, less energy consumption and is suitable for high voltage and low current driving.

In order to solve the above technical problems, the technical solution adopted by the utility model is:

The constant current control circuit for LED display device of the utility model comprises an LED light emitting module group composed of at least two LED light emitting units and at least one constant current module, all LED light emitting units and constant current modules are connected in series, Each LED light-emitting unit is connected in parallel with a switch control module that controls the LED light-emitting unit to be turned on or off by a PWM signal, and an on-off control module that controls its conduction or disconnection is also provided in the constant current module; The on-off control module sends a PWM signal to disconnect the constant current module when all the switch control modules in the LED lighting module receive the PWM signal to turn off the corresponding LED lighting unit.

The switch control module is a MOS transistor, the gate of which is connected to the PWM signal control terminal of the peripheral MCU, and its source and drain are parallel connected to the two ends of the corresponding LED light emitting unit.

The LED light-emitting unit is composed of at least one group of R, G, and B color lamp groups connected in series; the switch control module is a three-channel LED driver chip, its model is P9827, and its connection method is as follows:

Its "1" pin, "2" pin and "3" pin are respectively connected to the negative poles of the R, G, and B lamp beads in this colored lamp group;

Its "4" pin is grounded;

Its "5" pin is connected with the "6" pin of the three-channel LED driver chip in the adjacent parallel or serial connection of the next LED lighting module;

Its "6" pin is connected with the PWM signal control terminal of the peripheral MCU; or it is connected with the "5" pin of the three-channel LED driver chip in the previous LED lighting module connected in series or in parallel;

Its "7" pin is vacant;

Its "8" pin is connected to the positive pole of the terminal voltage of the LED lighting module.

The terminal voltage at both ends of the LED lighting module is 12V-36V.

The integrated chip type LED light-emitting module of the utility model includes at least two single-color or R, G, B three-color light-emitting diodes, and the light-emitting diodes are connected in series. The source and drain of the peripheral MOS transistor are connected to the leads, and the gate of the MOS transistor is connected to the output terminal of the PWM signal of the peripheral MCU device.

The LED display device of the present invention includes several groups of LED light-emitting modules and PWM signal control circuits. The LED light-emitting modules can be connected in parallel or in series, wherein each group of LED light-emitting modules consists of at least two LED light-emitting unit or at least two groups of LED light-emitting units composed of parallel or series-connected LED colored light groups and a constant current module connected in series, and connected in parallel at both ends of each LED light-emitting unit is a PWM signal that controls the LED to emit light. A switch control module for turning on or off the unit, and an on-off control module to control its on or off in the constant current module; the on-off control module is received by all the switch control modules in the LED lighting module When the PWM signal of the corresponding LED light-emitting unit is turned off, a PWM signal for disconnecting the constant current module is sent.

The switch control module is a MOS transistor, the gate of which is connected to the PWM signal control terminal of the peripheral MCU, and its source and drain are parallel connected to the two ends of the corresponding LED light emitting unit.

Compared with the prior art, the utility model will constitute the connection structure between each LED light-emitting unit and the constant current module in several LED light-emitting modules of a large-scale LED display device or a full-color LED lamp group, by the prior art The parallel connection is changed to a series connection structure, and a switch control module is connected in parallel at both ends of each LED light-emitting unit. At the same time, an on-off control module is provided in the constant current module. The LED light-emitting module is driven by high voltage and low current. All switch control modules and the on-off control module are controlled by PWM signals from peripherals. When the switch control module corresponding to a certain LED light-emitting unit receives the conduction signal of PWM, the switch control module is short-circuited, and the corresponding LED light-emitting unit does not emit light, and the current flows through the short-circuited switch control module to the next LED light-emitting unit ; When all the LED light-emitting units in the module are turned off, in order to reduce energy consumption, the control signal received by the on-off control module is a PWM signal that can stop the constant current module from working.

The utility model connects the LED light-emitting unit and the constant current module in the LED light-emitting module in series, and adopts high-voltage (12V-36V) low-current drive, and the length of the LED light-emitting module composed of several LED light-emitting units can be Up to 20 meters, the LED display device or full-color LED lamp group composed of it has low energy consumption, less wire material, and neat and simple wiring, which can not only reduce material and electric energy costs, but also greatly reduce labor costs due to easy installation. It can also greatly improve the installation efficiency.

Description of drawings

FIG. 1 is a schematic block diagram of an LED constant current control circuit in the prior art.

Fig. 2 is one of the block diagrams of the constant current control circuit of the present invention.

Fig. 3 is the second block diagram of the constant current control circuit of the present invention.

Fig. 4 is the third block diagram of the constant current control circuit of the present invention.

Fig. 5 is a schematic block diagram of the integrated LED lighting module of the present invention.

Fig. 6 is a schematic circuit diagram of the LED lighting module of the present invention.

Fig. 7 is one of the schematic circuit diagrams of the LED display device adopting the LED lighting module of the present invention.

Fig. 8 is the second schematic diagram of the circuit of the LED display device adopting the LED lighting module of the present invention.

FIG. 9 is a schematic circuit diagram of various LED lighting modules in the prior art.

The reference signs are as follows:

LED lighting module 1, LED lighting unit 2.

Detailed ways

As shown in Figure 2, the constant current control circuit for LED display device of the present invention is composed of several LED light emitting units 2 and at least one constant current module, the constant current control circuit can be used as an independent LED light emitting module 1, in the LED lighting module 1, several LED lighting units 2 and constant current modules are connected in series, and a switch control module is connected in parallel to each LED lighting unit 2, and in the constant current module There is also an on-off control module for controlling its on-off or off.

As shown in Figure 3 and Figure 4, the switch control module is a MOS tube (also can be a control module composed of transistors), the gate of the MOS tube is connected to the PWM signal control terminal of the peripheral MCU, and its source The electrode and the drain are connected to the two ends of the corresponding LED light emitting unit 2 in parallel.

The LED lighting unit 2 can be a single LED lamp bead, or a group of colored lamp groups composed of red (R) green (G) blue (B) LED lamp beads connected in series, wherein R, G, and B can be They can be connected in series or in parallel.

The terminal voltage of the above-mentioned LED lighting module 1 is driven by high voltage and low current, and the brightness of each LED lighting unit 2 is controlled by the switch control module by turning on or off the LED lighting unit 2 using PWM signals.

The high voltage is determined according to the number of LED light-emitting units 2 connected in series. For example, there are three LED light-emitting units 2 in the LED light-emitting module 1, and each LED light-emitting unit 2 only contains a 20mA low-power blue light wick. Then, its The terminal voltage can be driven by a voltage above 9V.

The constant current module in each group of LED lighting modules 1 is used to control the current of the LED modules connected in series, so that each LED lighting unit 2 can work within a reasonable current range; when all the switches in the LED lighting module 1 are controlled When the modules are all in the conduction state (that is, the corresponding LED light-emitting unit 2 has no current flowing), in order to reduce the energy consumption of the LED light-emitting module 1, the utility model conducts the control constant current module in the LED light-emitting module 1 Or the on-off control module that is disconnected is set to the disconnected state, that is, the constant current module is in a standby state without power consumption.

Take Figure 3 as an example:

1) "Control signal 1", "Control signal 2", and "Control signal 3" respectively control the first MOS transistor M1, the second MOS transistor M2, and the third MOS transistor M3 (hereinafter referred to as M1, M2, and M3 respectively).

When the PWM signal output by "control signal 1" makes M1 turn on, and the PWM signals output by "control signal 2" and "control signal 3" make M2 and M3 turn off respectively, M1 turns on, and M2 and M3 turn off. , the terminal voltage of the LED1 light-emitting unit corresponding to M1 tends to zero because the current is short-circuited by M1, and the LED1 light-emitting unit is in a non-light state at this time.

The current flowing through M1 normally flows through the LED2 light-emitting unit and the LED3 light-emitting unit so that they are in a lighting state.

As long as one of M1, M2 and M3 is in a conduction state, the constant current module is in a working state. In this state, since the terminal voltage of the LED light-emitting module 1 is a certain value, once the resistance value in the series circuit becomes smaller (that is, when there are LED light-emitting units 2 in the off state), other LEDs in the circuit will emit light. The terminal voltages of the unit 2 and the constant current module will rise, and when the terminal voltages of other LED lighting units 2 rise to their allowable upper limit, the feedback circuit in the constant current module will offset the voltage increase (the The structure of the feedback circuit can be a conventional structure in the prior art). That is to say, at this time, the constant current module will raise its own voltage, so that the LED light emitting unit 2 can work at a constant voltage and a constant current state.

2) When the PWM signals output by "control signal 1", "control signal 2" and "control signal 3" all make the corresponding M1, M2 and M3 turn on, the control signal 4 will send a shutdown signal to the constant current module PWM signal, this method can reduce the energy consumption of the constant current module.

The structure shown in FIG. 3 can be extended to a combination of several groups of LED lighting modules 1 as shown in FIG. 4 under the condition that the voltage at the terminal 1 of the LED lighting module is controllable and safe.

Using high voltage such as 12V power supply, the current is one-third of the existing technology structure, the advantage of high voltage and low current is that you can use longer wires to connect, avoiding the loss between the wires and causing the LED lighting module 1 to fail. Normal work, if the original way of 5V or lower voltage power supply is used, the LED module will not be able to pull too long due to the wear and tear of the wire. The utility model can use thinner wires as connecting wires, thereby saving materials.

The greater the current, the greater the line loss. This is largely unfavorable for energy-saving LEDs. The more power sources are used, the more complicated the wiring connections for workers are. These are the disadvantages of the low-voltage structure of the prior art.

The utility model adopts PWM mode to adjust the brightness of the LED light-emitting units 2 in each LED light-emitting module 1, so as to achieve less power consumption and line loss problems, and it can also improve the consistency of the current of the same LED light-emitting unit 2.

As shown in Figure 6 (Figure 7 shows an extension of the structure in Figure 6), it is one of the practical application examples of the present utility model.

Wherein the LED light emitting unit 2 is a group of R, G, B color lamp groups connected in series, which forms a group of LED light emitting modules 1 with a chip of model P9827, wherein three groups of LED light emitting modules 1 are connected in parallel, Between the "8" pin and the "1" pin, between the "1" pin and the "2" pin, between the "2" pin and the "3" pin in each chip, there is a "6" pin respectively. The MOS tube controlled by the PWM signal input by the "pin.

The circuit in this example is connected as follows:

Its "1" pin, "2" pin and "3" pin are respectively connected to the negative poles of the R, G, and B lamp beads in this colored lamp group;

Its "4" pin is grounded, and a built-in constant current module is connected to this pin, which is the constant current module of this LED lighting module 1 (when the connection method is the structure shown in Figure 7, the previous LED lighting module The "4" pin of group 1 is connected with the anode of the terminal voltage of the next LED lighting module 1, so that many LED lighting modules 1 can be connected in series).

Its "5" pin is connected with the "6" pin of the three-channel LED driver chip in the adjacent parallel or serial connection of the next LED lighting unit 2, and this pin outputs the PWM signal;

Its "6" pin is connected with the PWM signal control terminal of the peripheral MCU, or connected with the "5" pin of the three-channel LED driver chip in the previous LED lighting unit 2 connected in series or in parallel;

Its "7" pin is vacant;

Its "8" pin is connected to the positive pole of the voltage of terminal 1 of this LED lighting module;

The terminal voltage at both ends of the LED lighting module 1 described in the utility model can be 12V-36V.

When the number of terminal pins of the driver chip can be made in the future, the utility model can be extended to the structure shown in FIG. 8 . The structure can greatly reduce the material cost, labor cost and energy consumption of the large-scale LED display device, and at the same time, can also greatly improve the installation efficiency, product stability and reliability due to the simple wiring structure.

As shown in Figure 5, the integrated patch LED lighting module of the present invention integrates at least two single-color or a group of R, G, and B three-color light-emitting diodes together as a plug-and-play light-emitting component. Its features are the same as the aforementioned constant current control circuit for LED display devices of the present invention: the integrated light emitting diodes are connected in series, and there are MOS tubes at both ends of each light emitting diode that can be connected with the peripherals respectively. The source and drain of the MOS tube are connected to the lead wire, and the gate of the MOS transistor is connected to the output terminal of the PWM signal of the peripheral MCU device.

Several groups of LED light emitting modules 1 and PWM signal control circuits can be combined into a large-scale LED display device of the present invention, which is characterized in that all LED light emitting modules 1 can be connected in parallel or in series, wherein each group of LED The light emitting module 1 is composed of at least two single-color LED light emitting units 2 or at least two groups of LED light emitting units 2 composed of parallel or serial LED color light groups and a constant current module connected in series. Each LED light emitting unit 2 A switch control module that controls the LED lighting unit 2 to be turned on or off by a PWM signal is connected in parallel at both ends, and an on-off control module that controls its conduction or disconnection is also provided in the constant current module; the on-off control module The module sends out a PWM signal to disconnect the constant current module when all the switch control modules in the LED lighting module 1 receive the PWM signal to turn off the corresponding LED lighting unit 2 .

Wherein, the switch control module is a MOS transistor, the gate of the MOS transistor is connected to the PWM signal control terminal of the peripheral MCU, and its source and drain are parallel connected to both ends of the corresponding LED light emitting unit 2 .

Claims (7)

1. A constant current control circuit for an LED display device, comprising an LED light emitting module (1) composed of at least two LED light emitting units (2) and at least one constant current module, characterized in that: all LED light emitting units (2) and the constant current module are connected in series, and a switch control module that controls the LED light emitting unit (2) to be turned on or off by a PWM signal is connected in parallel on each LED light emitting unit (2). The module is also provided with an on-off control module to control its on-off or off; all switch control modules in the LED light-emitting module (1) of the on-off control module receive a signal to turn off the corresponding LED light-emitting unit (2). When the PWM signal is issued, the PWM signal to disconnect the constant current module is sent. 2. The constant current control circuit for LED display device according to claim 1, characterized in that: the switch control module is a MOS tube, and the gate of the MOS tube is connected to the PWM signal control terminal of the peripheral MCU. Its source and drain are connected in parallel to the two ends of the corresponding LED light emitting unit (2). 3. The constant current control circuit for LED display device according to claim 1, characterized in that: said LED light emitting unit (2) is composed of at least one group of R, G, B colored lamp groups connected in series; The switch control module is a three-channel LED driver chip, its model is P9827, and its connection method is as follows: Its "1" pin, "2" pin and "3" pin are respectively connected to the negative poles of the R, G, and B lamp beads in this colored lamp group; Its "4" pin is grounded; Its "5" pin is connected with the "6" pin of the three-channel LED driver chip in the adjacent parallel or serial connection of the next LED lighting module (1); Its "6" pin is connected with the PWM signal control terminal of the peripheral MCU; or it is connected with the "5" pin of the three-channel LED driver chip in the previous LED lighting module (1) connected in series or in parallel. connected; Its "7" pin is vacant; Its "8" pin is connected with the positive pole of the terminal voltage of the LED lighting module (1). 4. The constant current control circuit for LED display device according to claim 3, characterized in that: the terminal voltage at both ends of the LED lighting module (1) is 12V-36V. 5. An integrated patch type LED lighting module, comprising at least two single-color or R, G, B three-color light-emitting diodes, characterized in that: the light-emitting diodes are connected in series, and two ends of each light-emitting diode are provided There are lead wires which can be connected to the source and drain of the MOS transistor of the peripheral respectively, and the gate of the MOS transistor is connected to the output terminal of the PWM signal of the MCU device of the peripheral. 6. An LED display device, comprising several groups of LED lighting modules (1) and PWM signal control circuits, characterized in that: the LED lighting modules (1) can be connected in parallel or in series, wherein each group The LED light-emitting module (1) is composed of at least two single-color LED light-emitting units (2) or at least two LED light-emitting units (2) composed of parallel or series-connected LED color light groups and a constant current module connected in series, A switch control module that controls the LED light-emitting unit (2) to be turned on or off by a PWM signal is connected in parallel at both ends of each LED light-emitting unit (2). An on-off control module; the on-off control module sends a signal to disconnect the constant current module when all the switch control modules in the LED light emitting module (1) receive a PWM signal to close the corresponding LED light emitting unit (2). PWM signal. 7. The LED display device according to claim 6, characterized in that: the switch control module is a MOS transistor, the gate of the MOS transistor is connected to the PWM signal control terminal of the peripheral MCU, and its source and drain The poles are parallel connected to the two ends of the corresponding LED light emitting unit (2).