JPH06111740A - Chip-in-glass fluorescent character display tube - Google Patents

Abstract

PURPOSE:To provide a chip-in-glass fluorescent character display tube in which a step-up converter circuit is put in a vacuum container and for which no printed substrate is used. CONSTITUTION:Anode-grid voltage is geneated by a step-up converter, a widely used device composed of oscillator 4, a comparator 5, a flip-flop circuit 3, transistors 10, 11, a coil 14, and a diode 15, and filament voltage is generated by four transistors 21. These are contained in a vacuum container.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-in-glass fluorescent display tube, and more particularly to a chip-in-glass fluorescent display tube used for display on POS, ECR, vehicle and the like.

[0002]

2. Description of the Related Art A chip-in-glass fluorescent display tube and its module, in which a driver IC bare chip is housed in a vacuum container, have a compact outer shape and a lighter weight due to a large reduction in the number of terminals.
It is expanding its market by lowering prices and improving reliability.

The structure of a conventional chip-in-glass fluorescent display tube will be described with reference to FIG.

The input / output electrode terminals of the driver IC bare chip 31 are connected to the wiring pads formed on the anode substrate 33 using the bonding wires 32, and the IC bare chips 31 and the bonding wires 32 are housed in a vacuum container. The chip-in-glass fluorescent display tube 34 has a significantly smaller number of external terminals 35 than a conventional fluorescent display tube. The external terminals 35 are connected via a lead frame 36 to a printed circuit board 30 on which element parts 39 such as ICs, capacitors, transformers and connectors are mounted to form a chip-in-glass fluorescent display module.

[0005]

In the above-described conventional chip-in-glass fluorescent display module, the driver IC is housed inside the fluorescent display tube, and the IC or passive element package is miniaturized, so that the element of the printed circuit board is reduced. The area occupied by component mounting has become remarkably small, and this structure has a drawback in that the useless printed circuit board portion becomes large, which greatly impedes manufacturing cost reduction.

Further, from the user side of the fluorescent display tube,
In order to obtain a desired light emission brightness, it is necessary to incorporate a power supply system higher than a normal IC drive voltage, which is one of the factors that increase the cost of the module.

In addition, in a vehicle-mounted fluorescent display tube, since the gap between the filament and the grid electrode is extremely narrowed because it is required to be driven by a battery and to obtain high brightness, it is necessary to consider vibrations and shocks, and to improve reliability. There are drawbacks.

It is an object of the present invention to provide a chip-in-glass fluorescent display tube having a highly reliable step-up converter built-in, which is inexpensive in manufacturing cost and module cost.

[0009]

The present invention is a driver IC.
In a chip-in-glass fluorescent display tube in which the input / output terminals of the bare chip are connected to wiring pads formed on the anode substrate by bonding wires and housed in a vacuum container, an oscillator, a comparator, a flip-flop circuit, and a transistor, A step-up converter including a coil and a diode is housed in the vacuum container.

[0010]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

In the first embodiment, as shown in FIG. 1, first, the oscillation frequency is determined by the oscillator or the capacitor 9 which is a timing constant. The output of the oscillator 4 is connected to the input of the flip-flop circuit 3 and the input of the AND circuit 2. The output of the flip-flop circuit 3 is output at a cycle of 1/2 of the frequency of the input oscillator 4. As a result, the transistor 10 connected to the output of the flip-flop circuit 3 repeatedly turns on and off, and the Darlington-connected transistor 11 turns on and off. This allows
Energy is stored in the coil 14 while the input voltage is on while the transistor 11 is on, and when the transistor 14 is off,
A counter electromotive force is generated in 4 and the capacitor 16 is charged through the diode 15 to become the voltage V ₀ . The output voltage V ₀ is fed back to the flip-flop circuit 3 after the voltage value divided by the resistors 7 and 6 is compared with the reference voltage 8 (V _Ref ) by the comparator 5. As a result, the output duty of the flip-flop circuit 3 changes and the output voltage is kept constant. The output voltage is V ₀ = V _Ref · (1
+ R7 / R6).

Next, regarding the filament voltage generating circuit, four transistors 21 are bridge-connected, the level shift circuit 20 is connected to the base of each transistor 21, and the transistor 21 is constantly struck by the control signals CNT and SIG (about 100 KHz). The cliff set is ON-OFF
The above operation is repeated and an AC voltage is output to the filament output E _f . This output voltage is stepped down by the input voltage and the regulator 17, and is set by the resistors 18 and 19.

The step-up converter circuit is built in the chip-in-glass fluorescent display tube.

FIG. 2 is a circuit diagram of the second embodiment of the present invention.

As shown in FIG. 2, the second embodiment can have the same function as that of the first embodiment by using the MOSFET 24 as the switching element.

[0017]

As described above, the present invention provides a chip-in-glass fluorescent display tube in which an input terminal of a driver IC bare chip is connected to a wiring pad formed on an anode substrate by a bonding wire and housed in a vacuum container. By installing a step-up converter consisting of a circuit, an oscillator, a comparator, a flip-flop circuit transistor, a coil and a diode in a vacuum container, the printed circuit board used in the conventional chip-in-glass fluorescent display module can be eliminated. This has the effect of reducing costs.

Further, it is not necessary for the user to prepare an anode power source for the fluorescent display tube, and the system cost can be reduced.

In addition, a structure with a large gap between the filament and the grid electrode is possible, which has the effect of improving reliability.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a second embodiment of the present invention.

FIG. 3 is a sectional view of an example of a conventional chip-in-glass fluorescent display tube.

[Explanation of symbols]

 1,9,16 Capacitor 2 AND circuit 3 Flip-flop circuit 4 Oscillator 5 Comparator 6,7,12,13,18,19 Resistor 8 Reference voltage 10,11,21 Transistor 14 Coil 15 Diode 17 Regulator 20 Level shift circuit 22 Inverter Circuit 23 Zener diode 24 MOSFET 30 Printed circuit board 31 IC bare chip 32 Bonding wire 33 Anode substrate 34 Chip-in-glass fluorescent display tube 35 External terminal 36 Lead frame 39 Element parts

Claims (1)

[Claims] 1. A chip-in-glass fluorescent display tube in which an input / output terminal of a driver IC bare chip is connected to a wiring pad formed on an anode substrate by a bonding wire and housed in a vacuum container, an oscillator, a comparator, and a flip-flop. A chip-in-glass fluorescent display tube, characterized in that a step-up converter including a drive circuit, a transistor, a coil and a diode is housed in the vacuum container.