CN200983242Y - A driving power circuit of vacuum fluorescence display - Google Patents

Abstract

The utility model discloses a vacuum fluorescence display actuating power circuit, which comprises three components of a DC/DC conversion fraction of broad voltage input, a Pulse-Width Modulation switch circuit, a voltage changer output circuit. The utility model can accomplish the functions of DC/DC and DC/AC at the same time, has the advantages of a wide input voltage range, strong capability, high effects, stability and security and is suitable in actuating purposes of different modules of VFD with the power consumption lower than 5W and other demands of DC/DC and DC/AC.

Description

A kind of vacuum fluorescent display driving power circuit

Technical field

The utility model relates to a kind of ray or the beam cathode-ray tube (CRT) of the luminous anode part of directive (electron-beam tube) selectively, more particularly relates to a kind of driving power circuit of vacuum fluorescent display.

Background technology

The principle of work of vacuum fluorescent display (VFD) is the filament emitting electrons, and electronics quickens to get on the fluorescent powder (anode) through aperture plate, makes light-emitting phosphor.Drive vacuum fluorescent display, Switching Power Supply must provide two groups of voltages, and one group is that alternating voltage is powered to filament, and another group is given grid and anode supply for high direct voltage.The driving power circuit of VFD should provide stable AC filament voltages (Ef) and gravity flow high pressure (VH) for VFD, and guarantees the precision height, and noise is little, and is safe and reliable.

The utility model content

Technical problem to be solved in the utility model provides a kind of efficient, and is stable, the precision height; noise is little, the VFD driving power of automatic protection of band and control function, and this circuit design can reach above requirement; and carrying load ability is strong, and peak power output can reach 5W.

Technical scheme: a kind of vacuum fluorescent display driving power circuit comprises three ingredients:

(1) wide voltage input DC/DC conversion portion: form electronegative pressure feedback, frequency compensation and inhibition surge circuit by a DC/DC conversion chip (U1) and peripheral circuit;

(2) PWM on-off circuit: form by U2 and peripheral circuit,, adjust Duty according to the variation of output voltage for power tube provides stable base stage switching signal, in case load is short-circuited, circuit will be arranged to 0% to Duty automatically, thereby disconnects output, holding circuit generation excess current;

(3) transformer output circuit: the peripheral components by the transformer and the back utmost point is formed, and provides filament voltage and VFD to drive the high voltage of Driver to VFD.

Described transformer output circuit has adopted anti-Garbage flashing circuit, has placed diode (D4) between the filter capacitor of VH and ground circuit.

The utlity model has following advantage:

1. wide voltage input design can realize the direct current input of 4.4V～36V, can guarantee stable voltage output. output power can reach the 5W. ripple can reach 0.1V.

2.PWM modulating mode, the PWM controller of employing voltage-type, output voltage values is accurate, and ripple is little, and noise is low, and short-circuit protection function is arranged.

3. program controlled mode is adopted in power supply may command design (stand-by energy-saving design), can the free switch power supply. and in addition, can make power supply enter holding state, save power consumption by programmed control.

4. band Garbage prevents design, and the Garbage circuit design can prevent that the VFD module from producing unnecessary VFD screen flicker because electronics is uncontrolled in power switch.

In a word, power circuit design of the present utility model can be finished and finish DC/DC simultaneously, the function of DC/AC. have wide input voltage range, carrying load ability is strong, efficiently, the characteristics of stable and safety. in use can control the output of VFD driving power by master routine. standby mode can be set, have the advantages that to save power supply power consumption. this circuit design is applicable to that power consumption is lower than the driving purposes of the various modules of VFD of 5W and other DC/DC, and DC/AC needs.

Description of drawings

Fig. 1 is the utility model circuit design drawing.

Embodiment

In conjunction with the accompanying drawings the utility model is described in further detail: as shown in Figure 1:

1. wide voltage input DC/DC conversion portion.

This partial circuit is used for realizing the conversion that is input to 5Vdc output of 4.4V-36Vdc. outside input stage Pin8 receives through C1 and the filtered wide voltage of C2. output stage Pin1 output is through adjusted voltage. this magnitude of voltage decides .C7 by the height of the sample circuit magnitude of voltage that the voltage comparator comparison R1 and the R2 of U1 inside forms, C8, the filtering circuit .BR1 that C9 forms output is a voltage dependent resistor (VDR), and purpose is to reduce the surge current of output.

2.PWM on-off circuit

This circuit mainly is made up of PWM IC (U2).In work, the 5 pin output switching signals of U2 are used for controlling the conducting of Q1 and ending.Thereby make transformer action, and the stable AC wave shape of secondary output (F1, F2) and high direct voltage (VH).This circuit adopts voltage pwm modulation control.By (R11, R12 R13) adjust the size of switch Duty timely, have guaranteed the stable of high voltage output to the sample circuit of high voltage (VH).Q2, R6, R7, R8, C17 are the readiness control circuit of PWM.Can control work and the holding state of U2 by the Stand_By port.When Stand_By is high level, the Q2 conducting, U2 enters holding state, and the output of transformer is turn-offed.Finish the electrical source consumption of VFD.When Stand_By was low level, Q2 ended, and U2 is in normal operating conditions, and transformer is powered to VFD.Two states can use control device such as single-chip microcomputer to come transition status, reaches the effect of saving electrical source consumption.In addition, when the VFD module is started shooting, can control the Stand_By port, realize the soft start of power supply, thereby prevent because the former thereby generation surge current of capacitive load.

3. transformer output circuit

The main effect of transformer is conversion when finishing DC/DC and DC/AC.One of them is that (Pin6 Pin8) directly exports the filament alternating voltage, and another one is by commutator tube (D1) output high direct voltage by transformer.The AC and DC voltage of its output can be by adjusting transformer the number of turn of primary and secondary recently finish.Driving force can reach 1A.This circuit has also adopted anti-Garbage flicker design.Between the filter capacitor of VH and ground circuit, placed diode (D4), purpose is in order to prevent the VFD modular power source in the moment of closing, and VH is because the electric weight of the storage of two electrochemical capacitors has little time to discharge rapidly and the electric field that causes the filament ejected electron of VFD to continue to obtain grid quickens and scintillation takes place.D4 can make power supply guarantee that in the moment of closing the filament voltage of VFD is not less than the voltage levvl of VH, thereby does not make electronics continue to obtain the energy acceleration of electric field, finally eliminates the generation of Garbage flicker.

Above said content only is the basic explanation under the utility model design, and according to any equivalent transformation that the technical solution of the utility model is done, all should belong to protection domain of the present utility model.

Claims (2)

1. vacuum fluorescent display driving power circuit comprises three ingredients:

(1) wide voltage input DC/DC conversion portion: form electronegative pressure feedback, frequency compensation and inhibition surge circuit by a DC/DC conversion chip (U1) and peripheral circuit;

(2) PWM on-off circuit: form by U2 and peripheral circuit,, adjust Duty according to the variation of output voltage for power tube provides stable base stage switching signal, in case load is short-circuited, circuit will be arranged to 0% to Duty automatically, thereby disconnects output, holding circuit generation excess current;

(3) transformer output circuit: the peripheral components by the transformer and the back utmost point is formed, and provides filament voltage and VFD to drive the high voltage of Driver to VFD.

2. vacuum fluorescent display driving power circuit according to claim 1 is characterized in that: described transformer output circuit has adopted anti-Garbage flashing circuit, has placed diode (D4) between the filter capacitor of VH and ground circuit.

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