Backlight LED constant current circuit

Abstract

The utility model relates to a backlight LED constant current circuit. The backlight LED constant current circuit comprises a light-emitting module, a sampling module and an amplifying module, the sampling module comprises a sampling resistor, and the sampling resistor is electrically connected with the light-emitting module; the amplification module is electrically connected with the sampling resistor. According to the scheme provided by the invention, the constant-current driving circuit which is simple in structure and relatively low in cost can be provided.

Description

Technical Field

[0001] The utility model relates to the technical field of display screens, in particular to a backlight LED constant current circuit. Background Art

[0002] There are two ways to light up the backlight of a liquid crystal display, one is an external DC current source, and the other is a constant current drive from a driver circuit board. Because the backlight of LCD liquid crystal modules generally uses LED light sources, LED is essentially a diode. According to the volt-ampere characteristics of the diode, when the diode is forward-conducted, the current increases exponentially with the voltage. At the same time, a small range of voltage changes will cause a large change in the current, and the brightness of the diode is directly related to the current, so LEDs are usually driven by constant current to ensure the stability of the LED brightness.

[0003] However, in the related art, most constant current driving circuits are driven by driving chips, but the circuit of the driving chip is relatively complex and the cost is relatively high. Utility Model Content

[0004] The purpose of the utility model is to overcome the deficiencies in the prior art and provide a backlight LED constant current circuit, which can provide a constant current driving circuit with a simple structure and low cost.

[0005] The purpose of this utility model is achieved through the following technical solutions:

[0006] In a first aspect, the present application provides a backlight LED constant current circuit, comprising: a light emitting module; a sampling module, the sampling module comprising a sampling resistor, the sampling resistor being electrically connected to the light emitting module; and an amplifying module, the amplifying module being electrically connected to the sampling resistor.

[0007] The light emitting module comprises a lamp LED3, a lamp LED2 and a lamp LED1. The lamp LED3 is electrically connected to a first end of the lamp LED2, and a second end of the lamp LED2 is electrically connected to a first end of the lamp LED1.

[0008] The light emitting module further includes a resistor R4, a first end of the resistor R4 is electrically connected to a second end of the lamp LED1, and a second end of the resistor R4 is used to be electrically connected to an external power source.

[0009] The amplification module includes a resistor R3, and the resistor R3 is electrically connected to the sampling resistor.

[0010] The amplification module further includes an operational amplifier U1A, and the resistor R3 is electrically connected to the operational amplifier U1A.

[0011] The amplification module further includes a resistor R2, and a first end of the resistor R2 is electrically connected to the operational amplifier U1A.

[0012] The amplification module further includes a MOS tube Q1, a gate of the MOS tube Q1 is electrically connected to the second end of the resistor R2, a source of the MOS tube Q1 is electrically connected to the sampling resistor, and a drain of the MOS tube Q1 is electrically connected to the lamp LED3.

[0013] A resistor R1 is also included, and the resistor R1 is electrically connected to the operational amplifier U1A.

[0014] It also includes an input interface, which is electrically connected to the operational amplifier U1A.

[0015] It also includes a power interface, which is electrically connected to the resistor R1.

[0016] Compared with the prior art, the utility model has at least the following advantages:

[0017] By setting up a light-emitting module, a sampling module and an amplifying module, the traditional complex and high-cost driving chip is replaced to provide a constant-current driving circuit for the backlight LED. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for use in the embodiments are briefly introduced below.

[0019] Figure 1 This is a functional module diagram of a backlight LED constant current circuit in one embodiment of the utility model;

[0020] Figure 2 FIG. 4 is a circuit diagram of a backlight LED constant current circuit in an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0022] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0023] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] In the related art, most constant current driving circuits are driven by a driving chip, but the circuit of the driving chip is relatively complex and the cost is relatively high.

[0025] In view of the above problems, an embodiment of the present application provides a backlight LED constant current circuit, which can provide a constant current driving circuit with a simple structure and low cost.

[0026] The technical solution of the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0027] See also Figure 1 A backlight LED constant current circuit includes: a light emitting module 100, a sampling module 200 and an amplifying module 300, wherein the sampling module 200 includes a sampling resistor, and the sampling resistor is electrically connected to the light emitting module 100; the amplifying module 300 is electrically connected to the sampling resistor.

[0028] It should be noted that, by providing the light emitting module 100 , the sampling module 200 and the amplifying module 300 , a conventional complex and high-cost driving chip is replaced to provide a constant-current driving circuit for the backlight LED.

[0029] See also Figure 2 Specifically, the light emitting module 100 includes a lamp LED3, a lamp LED2 and a lamp LED1, the lamp LED3 is electrically connected to a first end of the lamp LED2, and a second end of the lamp LED2 is electrically connected to a first end of the lamp LED1.

[0030] It should be noted that the light LED3, the light LED2 and the light LED1 are all backlight LEDs.

[0031] See also Figure 2 Specifically, the light emitting module 100 further includes a resistor R4, a first end of the resistor R4 is electrically connected to a second end of the lamp LED1, and a second end of the resistor R4 is used to be electrically connected to an external power source.

[0032] It should be noted that the resistor R4 is a current limiting resistor for protecting the lamp LED, wherein the external power supply is used to supply power to the lamp LED3, the lamp LED2 and the lamp LED1.

[0033] See also Figure 2 In one embodiment, the amplification module 300 includes a resistor R3, and the resistor R3 is electrically connected to the sampling resistor. Specifically, the amplification module 300 also includes an operational amplifier U1A, and the resistor R3 is electrically connected to the operational amplifier U1A. Specifically, the amplification module 300 also includes a resistor R2, and the first end of the resistor R2 is electrically connected to the operational amplifier U1A. More specifically, the amplification module 300 also includes a MOS tube Q1, the gate of the MOS tube Q1 is electrically connected to the second end of the resistor R2, the source of the MOS tube Q1 is electrically connected to the sampling resistor, and the drain of the MOS tube Q1 is electrically connected to the lamp LED3.

[0034] It should be noted that the load current enters from VLED. When it is suddenly increased by external interference, the voltage of the sampling resistor R5 will increase, the input voltage of the in-phase terminal of the operational amplifier U1A remains unchanged, and the voltage of the inverting input terminal increases, which in turn causes the voltage output by the operational amplifier U1A to decrease, thereby reducing the gate voltage of the MOS tube Q1, reducing the current between the drain and the source, and finally reducing the load current, so that the current remains stable. Similarly, the load current increases after feedback regulation because the interference is reduced, so that the current is maintained in a stable state. In this way, the above-mentioned entire circuit constitutes a negative feedback closed system. Thereby achieving constant load current.

[0035] See also Figure 2 In one embodiment, a resistor R1 is further included, and the resistor R1 is electrically connected to the operational amplifier U1A.

[0036] It should be noted that the resistor R1 is also a current limiting resistor used to protect the circuit.

[0037] See also Figure 2 In one embodiment, it also includes an input interface, which is electrically connected to the operational amplifier U1A.

[0038] It should be noted that the input interface VIN is an input voltage interface, which is electrically connected to the positive electrode of the operational amplifier U1A.

[0039] See also Figure 2In one embodiment, it also includes a power interface, which is electrically connected to the resistor R1.

[0040] It should be noted that the power interface VCC is a direct current interface.

[0041] The scheme of the present application has been described in detail above with reference to the accompanying drawings. In the above embodiments, the descriptions of the various embodiments have their own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. Those skilled in the art should also be aware that the actions and modules involved in the specification are not necessarily required for the present application. In addition, it can be understood that the steps in the method of the embodiment of the present application can be adjusted in order, merged and deleted according to actual needs, and the modules in the device of the embodiment of the present application can be merged, divided and deleted according to actual needs.

[0042] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A backlight LED constant current circuit, characterized in that: include: Light emitting module; A sampling module, the sampling module comprising a sampling resistor, and the sampling resistor is electrically connected to the light emitting module; and An amplifying module, wherein the amplifying module is electrically connected to the sampling resistor.

2. The backlight LED constant current circuit according to claim 1, characterized in that: The light emitting module comprises a lamp LED3, a lamp LED2 and a lamp LED1. The lamp LED3 is electrically connected to a first end of the lamp LED2, and a second end of the lamp LED2 is electrically connected to a first end of the lamp LED1.

3. The backlight LED constant current circuit according to claim 2, characterized in that: The light emitting module further includes a resistor R4, a first end of the resistor R4 is electrically connected to a second end of the lamp LED1, and a second end of the resistor R4 is used to be electrically connected to an external power source.

4. The backlight LED constant current circuit according to claim 2, characterized in that: The amplification module includes a resistor R3, and the resistor R3 is electrically connected to the sampling resistor.

5. The backlight LED constant current circuit according to claim 4, characterized in that: The amplification module further includes an operational amplifier U1A, and the resistor R3 is electrically connected to the operational amplifier U1A.

6. The backlight LED constant current circuit according to claim 5, characterized in that: The amplification module further includes a resistor R2, and a first end of the resistor R2 is electrically connected to the operational amplifier U1A.

7. The backlight LED constant current circuit according to claim 6, characterized in that: The amplification module further includes a MOS tube Q1, a gate of the MOS tube Q1 is electrically connected to the second end of the resistor R2, a source of the MOS tube Q1 is electrically connected to the sampling resistor, and a drain of the MOS tube Q1 is electrically connected to the lamp LED3.

8. The backlight LED constant current circuit according to claim 6, characterized in that: A resistor R1 is also included, and the resistor R1 is electrically connected to the operational amplifier U1A.

9. The backlight LED constant current circuit according to claim 8, characterized in that: It also includes an input interface, which is electrically connected to the operational amplifier U1A.

10. The backlight LED constant current circuit according to claim 8, characterized in that: It also includes a power interface, which is electrically connected to the resistor R1.

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