CN201007897Y - A DC-driven vacuum fluorescent display filament lighting circuit - Google Patents

Abstract

The utility model discloses a filament lighting circuit of a DC-driven vacuum fluorescent display screen, which is mainly composed of resistors R1-R2, capacitors C1-C3 and diodes D1-D4. Coupling to the filament of the vacuum fluorescent display screen by means of a capacitive electric field, so that the current flows through the filament of the vacuum fluorescent display screen to achieve the purpose of heating the filament; the utility model can simplify the circuit, reduce the volume, reduce the cost, and stabilize the voltage; and The difficulty of circuit processing and production can be reduced, and the production efficiency can be improved.

Description

A DC-driven vacuum fluorescent display filament lighting circuit

technical field

The utility model relates to the field of vacuum displays, in particular to a filament lighting circuit for a DC-driven vacuum fluorescent display (VFD).

Background technique

At present, the known vacuum fluorescent display filament lighting circuit needs to work floating. In practical applications, such as automobiles, outdoor portable instruments, home appliances, industrial control, etc., DC-AC conversion circuits are generally used to obtain pulse voltages for vacuum fluorescent displays. The filament provides power. The use of a DC-AC conversion circuit requires a transformer, which transmits energy through a magnetic field. Using a transformer to complete the isolation and floating design of the power supply requires two windings, namely a primary winding and a secondary winding. The winding needs to change the current to induce an alternating magnetic field on the magnetic material, and then there is an induced electromotive force on the secondary winding, and the voltage and current energy on the secondary winding can light up the VFD filament, while the primary winding The current change of the winding needs to be provided by an oscillating circuit, or the same type of IC. The signal energy provided by the oscillating circuit is generally weak, and it is difficult to meet the needs of transferring energy on the transformer. In this way, a power tube must be added to drive. If the voltage of the secondary winding is to be stable, it must be fed back to the oscillating circuit for comparison and control. It is necessary to use an optocoupler and a voltage reference source. In this way, the number of components on the circuit is very large and the volume is large, resulting in high circuit cost and low output voltage. Unstable; moreover, it is difficult to design and manufacture.

Utility model content

The purpose of the utility model is to provide a DC-driven vacuum fluorescent display filament lighting circuit for the disadvantages of high cost, large volume and unstable output voltage in the prior art.

The technical scheme adopted by the utility model to solve the technical problem is: a vacuum fluorescent display filament lighting circuit, which is mainly composed of resistors R1-R2, capacitors C1-C3 and diodes D1-D4; one end of resistor R1 and capacitor C1 One end is connected, the other end of the capacitor C1 is connected to the anode of the diode D1 and the cathode of the diode D2 respectively, the cathode of the diode D1 is connected to the cathode of the diode D3, the resistor R2, and the capacitor C3 are connected to each other, the other end of the resistor R2 is connected to the other end of the capacitor C3 , the anode of the diode D2, the anode of the diode D4 are connected to each other, the anode of the diode D3 is connected to the cathode of the diode D4 and the capacitor C2, and the other end of the capacitor C2 is grounded; the two ends of the filament of the vacuum fluorescent display screen are respectively connected to the capacitor C3 on both ends.

Further, the resistance value of the resistor R1 is 0-30Ω, the resistance value of the resistor R2 is 8-10KΩ, the capacitance values of the capacitors C1 and C2 are 1-10uF, the capacitance value of the capacitor C3 is 20000pF-10uF, and the diode D1- D4 is 1N4148 or 1N4144.

The beneficial effects of the utility model are: the utility model utilizes the communication and direct isolation characteristics of the capacitor to couple energy to the filament of the vacuum fluorescent display screen through the electric field of the capacitor, so that the current flows through the filament of the vacuum fluorescent display screen to heat the filament The purpose of adopting the utility model can simplify the circuit, reduce the volume, reduce the cost, and stabilize the voltage; and can reduce the difficulty of circuit processing and production, and improve production efficiency.

Description of drawings

Further illustrate the utility model below in conjunction with accompanying drawing and embodiment, the purpose and effect of the utility model will become more obvious.

Fig. 1 is a schematic circuit diagram of the utility model;

Fig. 2 is an application example diagram of the utility model.

Detailed ways:

The utility model can adopt the direct current drive mode, take a cycle of pulse width energy on the system power supply (such as 3.3V, 2.5V, 1.8V, 1.2V, etc.) current characteristics), add a DC blocking capacitor to the positive pulse and the power supply ground to achieve the purpose of electrical insulation from the logic working ground, and connect a resistor in series in front of the DC blocking capacitor to adjust the pulse energy and adjust the brightness of the vacuum fluorescent display , the capacitance of the DC blocking capacitor determines the size of its coupling energy. Add a bridge rectifier at the back end of the DC blocking capacitor, and then add a capacitor filter to convert the pulse into DC, and add a large resistance resistor to The excess charge is discharged to complete the filament DC driving mode of the vacuum fluorescent display.

Specifically, as shown in Figure 1, the vacuum fluorescent display filament lighting circuit is a DC drive mode circuit, which is mainly composed of resistors R1-R2, capacitors C1-C3 and diodes D1-D4; one end of the resistor R1 is connected to the pulse input signal line The other end is connected to the capacitor C1, the other end of the capacitor C1 is connected to the anode of the diode D1 and the cathode of the diode D2 respectively, the cathode of the diode D1 is connected to the cathode of the diode D3, the resistor R2, and the capacitor C3 are connected to each other, and the other end of the resistor R2 The other end of the capacitor C3, the anode of the diode D2 and the anode of the diode D4 are connected to each other, the anode of the diode D3 and the cathode of the diode D4 are connected to the capacitor C2, and the other end of the capacitor C2 is grounded. The two ends of the vacuum fluorescent display filament are respectively connected to the two ends of the capacitor C3.

An application example is shown in Figure 2. The pulse width controller automatically adjusts the pulse width according to the output voltage of the DC power supply to achieve the purpose of outputting a constant voltage from the DC power supply. In the figure, the upper and lower MOS transistors Q1 and Q2 are turned on alternately under the control of the pulse width controller, and a square wave with a DC component is formed between the two MOS transistors. The DC power supply is set according to the needs of the actual circuit. The effective value of the intermediate energy square wave follows the value of the DC power supply and is fixed at a constant value, thereby stabilizing the effective value of the voltage on the VFD filament. Take this square wave, use the communication and direct isolation characteristics of the capacitor, and couple the energy to the VFD filament through the electric field of the capacitor, so that the current flows through the VFD filament to achieve the purpose of heating the filament, because electrons cannot pass through the insulating medium of the capacitor, The energy can only be coupled through the electric field, so the levitation is realized electrically.

The parameters of each component are as follows, the upper and lower MOS tubes Q1 and Q2 can be IRL7833, NTD110N02R or AO4406, the voltage of the battery power supply is 3.3-12V, the inductor L1 is 1-4.7uH, the resistance of the resistor R1 is 0-30Ω, and the resistor R2 The resistance value of the capacitor is 8-10KΩ, the capacitance value of the capacitor C1 and C2 is 1-10uF, the capacitance value of the capacitor C3 is 20000pF-10uF, and the diode D1-D4 is BAT54S, 1N4148 or 1N4144.

Because the circuit of this scheme extracts energy pulse power supply on DC-DC, the DC-DC circuit has stable power supply, fast response speed, and high quality, so the effective value voltage is stable and is not affected by the fluctuation of the input power supply, and it is convenient to realize the compatibility of AC and DC power supply .

Except for the technical features described in the instructions, all are known technologies by those skilled in the art.

The above-described embodiments are used to explain the utility model, rather than to limit the utility model. Within the spirit of the utility model and the protection scope of the claims, any amendments and changes made to the utility model all fall into the scope of the utility model. protected range.

Claims (2)

1. a direct drive formula filament spot circuit of vacuum fluorescent display screen is characterized in that, it mainly is made up of resistance R 1-R2, capacitor C 1-C3 and diode D1-D4; Resistance R 1 one ends link to each other with capacitor C 1 one ends, capacitor C 1 other end is connected with each other with the anode of diode D1 and the negative electrode of diode D2 respectively, the negative electrode of the negative electrode of diode D1 and diode D3, resistance R 2, capacitor C 3 are connected with each other, the anode of the anode of the other end of the other end of resistance R 2 and capacitor C 3, diode D2, diode D4 is connected with each other, the negative electrode of the anode of diode D3 and diode D4 and capacitor C 2 are connected with each other, the other end ground connection of capacitor C 2; The two ends of described vacuum fluorescent display screen filament are connected on respectively on the two ends of capacitor C 3.

2. direct drive formula filament spot circuit of vacuum fluorescent display screen according to claim 1, it is characterized in that, the resistance of described resistance R 1 is 0-30 Ω, the resistance of resistance R 2 is 8-10K Ω, the appearance value of capacitor C 1, C2 is 1-10uF, the appearance value of capacitor C 3 is 20000pF-10uF, and diode D1-D4 is 1N4148 or 1N4144.

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