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Power supply circuit of fluorescence display device

A power supply circuit and display technology, applied in the direction of static indicators, instruments, electrical components, etc., can solve the problems of large noise, multiple costs and time, high power consumption, etc.

Inactive Publication Date: 2008-03-05
NORITAKE ITRON CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] (1) Generate loud noise;
[0012] (2) More cost and time are needed to design the power supply;
[0014] (4) Larger power consumption is required

Method used

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  • Power supply circuit of fluorescence display device
  • Power supply circuit of fluorescence display device
  • Power supply circuit of fluorescence display device

Examples

Experimental program
Comparison scheme
Effect test

no. 1 example

[0039] FIG. 1 is a circuit diagram showing a main part of a power supply circuit according to an embodiment (first embodiment) of the present invention. The power supply circuit 100 includes a capacitor (input smoothing capacitor) CO, a boost coil (inductance element) L, a boost circuit 13, a switching transistor (field effect transistor) TR, a variable resistor (voltage adjustment resistor) 14, and a PWM control circuit 15 and resistors R1 and R2. The power supply circuit has an input terminal Pin, an output terminal Pout, a filament terminal F1 (first terminal) and a filament terminal F2 (second terminal).

[0040] The input voltage (DC voltage) Vin is applied to the input terminal Pin. The DC voltage VDD2 for anode / gate is output from the output terminal Pout. A cathode (filament) 6 of the vacuum fluorescent display tube 1 is connected between filament terminals F1 and F2.

[0041] In the power supply circuit 100 , the boost coil L is provided on the current path Lin bet...

no. 2 example

[0097] FIG. 4 shows a main part of a power supply circuit according to another embodiment (second embodiment) of the present invention. The power supply circuit 200 includes a control circuit 16A, a boost circuit 17 and a cutoff circuit 18A, and has an input terminal Pin, an output terminal Pout, and filament terminals F1 and F2. A DC voltage (input voltage) Vin is applied to the input terminal Pin. The DC voltage VDD2 for anode / gate is output from the output terminal Pout. A cathode (filament) 6 of the vacuum fluorescent display tube 1 is connected between filament terminals F1 and F2.

[0098] The cut-off circuit 18A includes a first switch SW1, a second switch SW2, a resistor R, diodes D1 and D2, and capacitors C1 and C2. The switches SW1 and SW2 are connected in series between the input line Lin for the DC voltage Vin and the ground (GND). In this series connection, the switch SW1 is on the input line Lin side of the DC voltage Vin, and the switch SW2 is on the ground s...

no. 3 example

[0142] FIG. 8 shows an application of the power supply circuit 200 shown in FIG. 4 . In the power supply circuit 300, the third and fourth switches SW3 and SW4 are connected in series between the input line Lin for the DC voltage Vin and the ground line. In this series circuit, the switch SW3 is located on the input line Lin side of the DC voltage Vin, and the switch SW4 is located on the ground line side. Capacitor C2 is connected between filament terminal F2 and node PB between switches SW3 and SW4.

[0143] The switch SW1 and the switch SW4 constitute a first switch pair, and the switch SW2 and the switch SW3 constitute a second switch pair. The control circuit 16B periodically and alternately turns on / off the first pair of switches ( SW1 and SW4 ) and the second pair of switches ( SW2 and SW3 ) in opposite directions.

[0144] That is, the control circuit 16B periodically repeats "simultaneously turning off the second switch pair (SW2 and SW3) while simultaneously turnin...

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PUM

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Abstract

A power supply circuit for a vacuum fluorescent display includes a boosting coil, input terminal, switching transistor, PWM control circuit, boosting circuit, first filament terminal, and second filament terminal. The boosting coil is provided in a current path to generate an induced voltage in accordance with a change in current flowing therein. The input terminal receives a DC voltage to be applied to one terminal of the boosting coil. The switching transistor is provided between the other terminal of the boosting coil and a ground line. The PWM control circuit periodically turns on / off the switching transistor. The boosting circuit generates a boosted voltage on the basis of an induced voltage generated at the other terminal of the boosting coil when the switching transistor is switched from ON to OFF. The first terminal is connected to the node between the other terminal of the boosting coil and the switching transistor. A DC voltage lower than the induced voltage generated at the other terminal of the boosting coil is applied to the second terminal.

Description

[0001] This application is a divisional application of the Chinese patent application "Power Circuit for Vacuum Fluorescent Display" (Application No. 200410064414.7) submitted on August 24, 2004. technical field [0002] The present invention relates to a power supply circuit attached to a vacuum fluorescent display. Background technique [0003] A vacuum fluorescent display is an electron tube that displays a desired pattern by causing electrons emitted from a cathode in a vacuum tube (housing) that is transparent on at least one side to strike a phosphor coated on an anode and cause the phosphor to emit light . Generally, as such a vacuum fluorescent display, a display having a structure of a triode vacuum tube having a grid for controlling behavior of electrons is most often used. [0004] FIG. 15 shows a conventional general vacuum fluorescent display and a circuit attached to the vacuum fluorescent display (see Japanese Patent Laid-Open No. 2002-260565 (Reference 1)). ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G09G3/22G09G3/12G09G3/20G09G3/30H02M3/07H02M3/155
Inventor 龟田胜士芝田和久中西浩寺上伸一江口登志英
Owner NORITAKE ITRON CORP
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