JPH0690601B2 - Fluorescent display tube drive circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a drive circuit for a fluorescent display tube, and more particularly to adjusting the brightness.

[Conventional technology]

FIG. 2 shows a conventional driving circuit for a fluorescent display tube. In the fluorescent display tube (1), electrons emitted from a direct heating filament (4) are accelerated by a grid electrode (3) to form an anode ( 2)
The fluorescent substance applied to the surface of the anode (2) is excited and emits light when the anode (2) and the grid electrode (3) are driven by the driving circuits (5), (6) and control. An arbitrary display can be obtained by controlling according to (7) and (8). Here, the drive circuits (5) and (6) for the anode (2) and the grid electrode (3) switch the power supply voltage V _{+ in} accordance with their control signals, and the anode (2) of the fluorescent display tube (1). And to the grid electrode (3). At that time, the brightness of the display depends on the voltage between the filament (4) and the grid electrode (3) and the anode (2) or the pulse width of the drive waveform.

However, in the conventional configuration, the drive voltage is determined by the DC power supply V ₊ of the drive circuit, and is usually fixed at a constant voltage. Therefore, when using multiple fluorescent display tubes side by side,
There is a drawback that it is difficult to match the brightness of each fluorescent display tube.

FIG. 3 is for solving this problem, and is disclosed in Japanese Patent Laid-Open No. 60-18429
It is shown in No. 3. In the figure, the anodes (2) and the grid electrodes (3) of a plurality of fluorescent display tubes (1) are connected in parallel to a DC power source V ₊ via a voltage adjusting circuit (10) described later, and a filament ( 4) is also connected in parallel. The voltage adjusting circuit (10) is provided in the drive circuit of each display tube and arbitrarily corrects variations in brightness. As shown in FIG. 4, a transistor (10a), a variable resistor (10b) and a resistor are provided. (10c), DC power supply V ₊
Is divided to supply a control voltage to the drive circuit side, that is, to the anode (2) and the grid electrode (3).

In the above structure, the relationship between the luminance of the fluorescent display tube (1) and the driving voltage is as shown in FIGS. The cathode (4) of the fluorescent display tube (1) is a direct heating filament, and the filament power supply is an AC power source to prevent the potential gradient caused by the voltage drop across the filament from appearing on the display as a luminance gradient. To use. When the lighting is not required, the midpoint M of the filament (4) power supply is set to the cutoff potential E _K so that the anode (2) or the grid (3) becomes negative with respect to the filament (4) potential. Therefore, the driving voltage ebc that determines the brightness of the fluorescent display tube (1) is as shown in FIG.

The drive circuits (5) and (6) of each fluorescent display tube (1) switch the input voltage V _D to the display tube according to the signals from the controls (7) and (8). _{If D} is made variable, the drive voltage ebc becomes variable, and the brightness can be adjusted according to FIG.

In the configuration shown in each of FIGS. 4A and 4B, each voltage adjusting circuit (10) is for easily realizing the above effect. It divides the DC power supply V ₊ and outputs V _D via the transistor (10a) to the V _{+ component} . Pressure value Therefore, the brightness of the display tube can be easily adjusted by changing the voltage division ratio. When the drive voltage value is variably controlled in this way, when a plurality of display tubes are arranged and used, variations in the brightness of the individual display tubes can be easily corrected.

[Problems to be solved by the invention]

However, this type of fluorescent display tube requires switching control of a high voltage anode voltage, but it is difficult to apply a high voltage that is switching controlled to the anode due to the breakdown voltage of the drive circuit, and the brightness is also low. It was limited.

Therefore, the present invention has been made in order to solve the above problems, while always applying a high voltage to the anode,
(EN) Provided is a driving circuit for a fluorescent display tube, which can easily adjust brightness by controlling a grid having a matrix structure by switching it at a low voltage and easily obtain high brightness.

[Means for solving problems]

The drive circuit of the fluorescent display tube according to the present invention is formed by applying fluorescent substances of a plurality of colors, and an anode to which a constant high voltage is applied, and electrons emitted from the filament are accelerated toward the anode, It is provided with a grid electrode having a matrix structure composed of scan electrodes and data electrodes for controlling the light emission of the fluorescent body, and is provided with a voltage adjusting circuit for controlling the drive voltage supplied to the grid electrodes, thereby making it possible to control the brightness. Is.

[Action]

According to the driving circuit of the fluorescent display tube according to the present invention, it is not necessary to adjust the driving voltage to the anode and only the driving voltage to the grid electrode is adjusted so that the luminance of the display tube capable of full-color display varies. In addition, the brightness can be easily corrected with a simple configuration.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
The figure shows an embodiment of the present invention, in which the fluorescent display tube (100) is formed by applying fluorescent substances of a plurality of colors and has a constant high voltage V _H.
And a scanning electrode (hereinafter, referred to as X-grid) for controlling the emission of the phosphor by accelerating electrons emitted from the filament (4) toward the anode (2). (3X) and data electrode (hereinafter referred to as Y grid)
(3Y) and a grid electrode having a matrix structure.

In such a fluorescent display tube (100), the electrons emitted from the filament (4) are accelerated by the voltage applied to the grid electrodes of the X grid (3X) and the Y grid (3Y), and a high voltage is generated. For example, a fluorescent substance applied to the surface of the anode emits light due to the collision energy at this time when it collides against the applied anode (2), and a plurality of X grids are arranged to form a matrix structure together with it. If a plurality of Y grids are arranged, and red, green, and blue phosphors are applied to the surface of the anode in accordance with this matrix structure and the applied voltage to each grid is arbitrarily selected, a color corresponding to this can be obtained. Luminescence can be obtained. In the display tube, the anode (2) may be applied with a constant high voltage.

Therefore, to adjust the brightness of the display tube (100),
It is not necessary to adjust the anode (2), and the adjustment can be simplified by adjusting only the grid electrode. That is, X grid control (8X), Y grid control (8X)
Driving circuit (6X), (6
The structure shown in FIG. 4 may be adopted for the voltage adjusting circuit (10) for Y), and the brightness can be easily adjusted by controlling the drive voltage supplied to the grid electrode.

Although the display device in which a plurality of fluorescent display tubes are arranged has been described in the above embodiment, the present invention is effective even when the brightness is internally adjusted even with one display tube.

〔The invention's effect〕

As described above, according to the present invention, fluorescent materials of a plurality of colors are applied, and an anode to which a constant high voltage is applied and electrons emitted from the filament are accelerated toward the anode, In a fluorescent display tube provided with a grid electrode having a matrix structure composed of a scanning electrode and a data electrode for controlling light emission of a light body, a voltage adjusting circuit for controlling a drive voltage supplied to the grid electrode is provided, It is possible to easily correct the brightness of the display tube by applying a constant high voltage to the anode and adjusting the voltage to the grid electrode, and to increase the constant high voltage to the anode simply by increasing the power supply voltage. It is possible to increase the energy of electrons that are applied and collide with the phosphor screen to achieve high brightness. Further, the display on / off control may be performed by controlling the low voltage applied to the grid electrode, and the driving circuit and the voltage adjusting circuit can use the elements having low withstand voltage,
With the simple structure, the drive voltage can be easily adjusted and the brightness can be easily adjusted.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 and 3 are conventional circuit diagrams, FIG. 4 is a circuit diagram of a voltage adjusting circuit used in the present invention, and FIG. 5 is a driving circuit. FIG. 6 is a characteristic diagram showing the relationship between voltage and luminance, and FIG. 6 is a waveform diagram showing the relationship between drive voltage, filament potential, and cutoff voltage. (1), (100) ... Fluorescent display tube, (2) ... Anode (3), (3X), (3Y) ... Grid (4) ... Filament (5), (6), (6X) ), (6Y) …… Drive circuit (10) …… Voltage adjustment circuit, V _H …… High-voltage power supply (8X), (8Y) …… X and Y grid control In the figures, the same symbols are the same or equivalent Shows the part.

Claims (2)

[Claims] 1. A fluorescent material of a plurality of colors is applied, an anode to which a constant high voltage is applied, and electrons emitted from a filament are accelerated toward the anode to control the light emission of the fluorescent material. In a fluorescent display tube provided with a grid electrode having a matrix structure composed of scanning electrodes and data electrodes, it is possible to control the brightness by providing a voltage adjusting circuit for controlling a drive voltage supplied to the grid electrode. Driving circuit for fluorescent display tube. 2. A plurality of the fluorescent display tubes are connected in parallel to a driving power source, each of which has an individual voltage adjusting circuit,
The driving circuit for a fluorescent display tube according to claim 1, wherein the luminance can be corrected.