Circuit for controlling starting voltage of backlight lamp of light guide panel

Abstract

The utility model belongs to the technical field of light guide panel backlight lamps, and particularly relates to a circuit for controlling the starting voltage of a light guide panel backlight lamp, which comprises a reference source circuit, a resistance voltage division circuit and a voltage comparator U2, the non-inverting input end of the voltage comparator U2 is electrically connected with the output end of the reference source circuit, and the non-inverting input end of the voltage comparator U2 is electrically connected with the output end of the resistance voltage division circuit. The reverse input end of the voltage comparator U2 is electrically connected with the output end of the resistance voltage division circuit, the output end of the voltage comparator U2 is connected to the base electrode of the triode Q1 through the resistor R1 and the voltage stabilizing diode Dw, and the output voltage of the collector electrode of the triode Q1 serves as the starting voltage. According to the utility model, the reference source circuit and the resistance voltage division circuit are arranged, and voltage comparison is carried out, so that the threshold voltage of circuit action can be set, the circuit is not influenced by fluctuation of an external power supply, and a starting voltage value is kept stable within a certain temperature change range.

Description

Technical Field

[0001] The utility model relates to the technical field of light guide panel backlight lamps, in particular to a circuit for controlling the starting voltage of a light guide panel backlight lamp. Background Art

[0002] Control panel products are widely used in various fields such as industrial control, medical instruments, and military equipment. In some special occasions, it is necessary to meet the requirement of lighting up when a specific power supply voltage value is reached. However, conventional control methods have large errors and are prone to malfunctions. Utility Model Content

[0003] The purpose of the utility model is to solve the technical problems existing in the background technology. To this end, a circuit for controlling the starting voltage of the backlight of a light-guiding panel is provided. First, a stable reference voltage is generated by an external power supply through a reference source device; the external power supply is divided by a resistor to obtain a sampled voltage value; then, the reference voltage is compared with the sampled voltage. Once the external power supply voltage reaches a threshold value, the comparison result causes the output of the voltage comparator to flip, driving the subsequent circuit to change state.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0005] A circuit for controlling the starting voltage of a backlight of a light guide panel comprises a reference source circuit, a resistor voltage divider circuit and a voltage comparator U2, wherein the same-direction input terminal of the voltage comparator U2 is electrically connected to the output terminal of the reference source circuit, the reverse input terminal of the voltage comparator U2 is electrically connected to the output terminal of the resistor voltage divider circuit, the output terminal of the voltage comparator U2 is connected to the base of a transistor Q1 via a resistor R1 and a voltage stabilizing diode Dw, and the output voltage of the collector of the transistor Q1 is used as the starting voltage.

[0006] The following is a technical solution further defined by the present utility model, wherein the reference source circuit includes a reference source device U1, wherein pin A of the reference source device U1 is grounded, pin C of the reference source device U1 is connected to pin ADJ and is connected to an input voltage VCC through a resistor R2, and pin C of the reference source device U1 is electrically connected to the same-direction input terminal of a voltage comparator U2 through a resistor R3.

[0007] The following is a technical solution further defined by the present invention, wherein the resistor voltage divider circuit includes resistors R4 and R5 connected in series; the other end of the resistor R4 is grounded, the other end of the resistor R5 is connected to the input voltage VCC, and the reverse input end of the voltage comparator U2 is connected to the line between the resistors R4 and R5.

[0008] The following is a technical solution further defined by the present utility model: resistors R6, R7 and a diode Dk are connected in series between the non-inverting input terminal and the output terminal of the voltage comparator U2.

[0009] The following is a technical solution further defined by the present invention: a resistor R8 is connected between the base and the emitter of the transistor Q1.

[0010] Compared with the prior art, the utility model has the following technical effects:

[0011] The utility model sets a reference source circuit and a resistor voltage divider circuit and performs voltage comparison to set a threshold voltage for circuit action, so that the circuit will not be affected by external power supply fluctuations and the starting voltage value can be kept stable within a certain temperature variation range.

[0012] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 It is a circuit connection diagram of the utility model. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0016] like Figure 1 As shown, a circuit for controlling the starting voltage of a backlight lamp of a light guide panel is provided, including a reference source circuit, a resistor voltage divider circuit and a voltage comparator U2.

[0017] The reference source circuit includes a reference source device U1, pin A of the reference source device U1 is grounded, pin C of the reference source device U1 is connected to pin ADJ and is connected to an input voltage VCC (i.e., an external power supply) through a resistor R2, and pin C of the reference source device U1 is electrically connected to the same-direction input terminal of the voltage comparator U2 through a resistor R3.

[0018] The resistor divider circuit includes resistors R4 and R5 connected in series; the other end of resistor R4 is grounded, the other end of resistor R5 is connected to input voltage VCC (ie, external power supply), and the reverse input end of voltage comparator U2 is connected to the line between resistors R4 and R5.

[0019] The output end of the voltage comparator U2 is connected to the base of the transistor Q1 through the resistor R1 and the voltage stabilizing diode Dw, and the output voltage of the collector of the transistor Q1 is used as the ignition voltage. Resistors R6, R7 and a diode Dk are connected in series between the non-inverting input end and the output end of the voltage comparator U2.

[0020] A resistor R8 is connected between the base and emitter of the transistor Q1.

[0021] In summary, U1 is the reference source device, and the circuit of this embodiment uses TL431. U2 is the voltage comparator, and the circuit of this embodiment uses GS331-TR. U1 stabilizes the external input power supply voltage to 2.5V and adds it to the same-direction input terminal of the voltage comparator. The reverse input terminal of the voltage comparator is connected to a resistor voltage divider circuit. Once this voltage divider value is higher than 2.5V of the reference source circuit, the transistor inside the voltage comparator is turned on and accepts external current injection. When this voltage divider value is lower than 2.5V of the reference source circuit, the transistor inside the voltage comparator always remains in the cut-off state. By changing the value of the voltage divider resistor at the reverse input terminal of the voltage comparator, the threshold voltage of the circuit action can be set.

[0022] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the utility model by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the utility model, or modify it into an equivalent embodiment of equivalent changes. Therefore, all equivalent changes made according to the shape, structure and principle of the utility model without departing from the content of the technical solution of the utility model should be included in the protection scope of the utility model.

Claims

1. A circuit for controlling the starting voltage of a backlight lamp of a light guide panel, characterized in that: It includes a reference source circuit, a resistor voltage divider circuit and a voltage comparator U2, wherein the same-direction input terminal of the voltage comparator U2 is electrically connected to the output terminal of the reference source circuit, the reverse input terminal of the voltage comparator U2 is electrically connected to the output terminal of the resistor voltage divider circuit, the output terminal of the voltage comparator U2 is connected to the base of the transistor Q1 through a resistor R1 and a voltage-stabilizing diode Dw, and the output voltage of the collector of the transistor Q1 is used as a starting voltage.

2. A circuit for controlling the starting voltage of a backlight lamp of a light guide panel as claimed in claim 1, characterized in that: The reference source circuit includes a reference source device U1, pin A of the reference source device U1 is grounded, pin C of the reference source device U1 is connected to pin ADJ and is connected to input voltage VCC through resistor R2, and pin C of the reference source device U1 is electrically connected to the same-direction input terminal of the voltage comparator U2 through resistor R3.

3. A circuit for controlling the starting voltage of a backlight lamp of a light guide panel as claimed in claim 1, characterized in that: The resistor voltage divider circuit includes resistors R4 and R5 connected in series; the other end of the resistor R4 is grounded, the other end of the resistor R5 is connected to the input voltage VCC, and the reverse input end of the voltage comparator U2 is connected to the line between the resistors R4 and R5.

4. A circuit for controlling the starting voltage of a backlight lamp of a light guide panel as claimed in claim 1, characterized in that: Resistors R6, R7 and a diode Dk are connected in series between the non-inverting input terminal and the output terminal of the voltage comparator U2.

5. The circuit for controlling the starting voltage of a backlight lamp of a light guide panel as claimed in claim 1, characterized in that: A resistor R8 is connected between the base and emitter of the transistor Q1.

Images