JPH0470896A - Large-sized discharge panel driving circuit - Google Patents

Abstract

PURPOSE:To make an auxiliary anode driving current larger at the peripheral part than at the center part and to hold the discharge of the whole panel to a constant characteristic by inputting a parabolic control waveform to the bases of transistors of an auxiliary anode driving circuit. CONSTITUTION:A constant current control circuit 15 is connected to the bases B of the transistors(TR) 12 in the auxiliary anode driving circuit 6 and outputs the parabolic signal to drive the TRs 12. Consequently, an auxiliary discharging current outputted from the collector C of each TR 12 varies in a parabolic shape after the start of discharging similarly to the output signal of the circuit 15. Then the constant current control circuit 15 outputs one parabolic waveform in each vertical scanning period of a discharge panel 1 to supply a large auxiliary anode current to the upper and lower peripheral parts which are harder to illuminate than the center part, thereby holding the discharge of the entirety in the vertical direction to the constant characteristic.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a large discharge panel drive circuit for a wall-mounted television or the like constructed using a large discharge panel.

[Prior art] Figure 3 shows, for example, the Institute of Electronics, Information and Communication Engineers technical report EID8.
9-73 is a configuration diagram of the conventional large discharge panel drive circuit shown in FIG.
) is the display anode, (3) is the auxiliary anode, (4) is the cathode, (5
) is the display anode drive circuit, (6) is the auxiliary anode drive circuit, (
7) is a cathode drive circuit.

FIG. 4 is a partially broken perspective view of main parts showing the configuration of the discharge panel for explaining an example of the discharge panel. In the figure, (8) is a front glass plate, (8) is a rear glass plate, (
10) is a rib, and (11) is a phosphor.

Figure 5 shows an auxiliary anode drive circuit [A] used in the conventional example, in which (12) is a transistor, (13)
14 is a current limiting resistor, (14) is a variable source circuit, (E) is an emitter of the transistor (12), (B) is a pace, and (C) is a collector.

Next, before explaining the operation of the above conventional example, the fourth
The operation of the discharge panel shown in the figure will be explained.

For example, as shown in Fig. 4, the discharge panel is constructed by printing a cathode (4) on a rear glass plate (9), and ribs (10) for dividing the discharge cells using color paste or the like on the rear glass plate (9). Configure.

- The front glass plate (8) is coated with phosphor (9) in the form of dots in units of discharge cells, and the display anode (2) and auxiliary anode (3) are formed from above. The front glass plate (8) and the rear glass plate (9) are connected to the display anode (2) and cathode (4).
They are stacked so that they are orthogonal to each other, the periphery is closed, and a discharge material such as xenon or argon is sealed inside.

In a discharge panel having such a configuration, the intersection between the cathode (4) and the display anode (2) serves as a discharge cell, and this discharge cell is separated from other discharge cells by ribs (10). Each of these discharge cells corresponds to one pixel of an image, and the discharge bulb 2 as a whole displays one image. The discharge cell applies a negative voltage pulse signal to the cathode (4) and displays the display anode (4).
Gas discharge is performed by applying a positive voltage pulse signal to 2) (hereinafter referred to as display discharge). This display discharge excites the phosphor (11) located at the bottom of the discharge cell to emit multicolor light.The discharge panel as a whole consists of a display anode (2) and a cathode ( 4) determine the light emission of each discharge cell.

On the other hand, the auxiliary anode (3) is made of glass plate (9) Ll
The auxiliary anode (3) is formed between two wooden display anodes (2) at the part corresponding to the valley of the rib (10), and this auxiliary anode (3) generates a weak discharge ( that's all
(referred to as auxiliary discharge). This auxiliary discharge (charged particles) diffuses into the discharge cell between the anodes (2) on both sides, putting the discharge cell in a state where display discharge is easy to occur.

As described above, the auxiliary anode (3) has the role of assisting the display discharge of the discharge cell by auxiliary discharge, and a high voltage needs to be applied to this auxiliary anode (3) at the start of the auxiliary discharge. After the discharge starts, it is necessary to maintain the auxiliary discharge stably. Therefore, the auxiliary anode drive circuit (6) for driving the auxiliary anode (3) becomes a circuit as shown in FIG.

In FIG. 5, the collector (C
) are connected to each auxiliary anode (3), the emitter (E) is connected to a power supply with a voltage value VSA through a current limiting resistor (13), and the pace (B) is connected to the negative of the variable 1i [i circuit (14)]. connected to the side. Further, the positive side of the variable power supply circuit (14) is connected to the power supply of voltage VSA. Therefore, the potential of the emitter of the transistor (12) is expressed by the following equation.

VE = VSA - VVR + VBE VE: Potential of emitter of transistor (12) V VR: Voltage of variable power supply (14) VBE: Voltage drop between pace and emitter of transistor (12) Therefore, discharge starts and transistor (12) If the collector (C) of is considered to be the same as being grounded,
A current IR expressed by the following equation flows through the current limiting resistor.

Current flowing through IR/current limiting resistor (13) ■R9 Potential difference between both ends of current limiting resistor (13) R Current limiting resistor (13)
If the resistance value of , auxiliary discharge does not start and the transistor (12) cr + collector (C) is considered to be released, the heavy pressure VS
A is directly applied to the auxiliary anode (3).

In this way, the auxiliary anode (3) has a voltage of V before starting the auxiliary discharge.
A high voltage necessary to start the discharge is applied by SA, and after the start of the auxiliary voltage, a current value IR determined by the voltage VVR of the variable power supply circuit (14) is applied, so that the discharge is stable.

A conventional large discharge panel drive circuit shown in FIG. 3 is constructed using the above-described auxiliary anode drive circuit and discharge panel, and its operation will be described above.

For example, in a discharge panel (1) with a size of about 20 inches, there are 320 auxiliary anodes (3). Therefore, the auxiliary anode drive circuit (6) includes three transistors (12).
It contains 20 pieces and drives each auxiliary anode (3). Cathode (4
) and the display anode (2) are also applied with necessary voltages by the cathode drive circuit (7) and display anode drive circuit (5), respectively.

When driving such a large discharge panel, the length of the auxiliary anode (3) and display anode (2), the gap length between the front glass plate (8) and the rear glass plate (3), etc. The driving voltage varies depending on the upper level, making the discharge unstable. In order to prevent this, the auxiliary anode (3) is divided into several blocks, and each block is connected to a variable power supply circuit (B) of the transistor (12).
14) to control the auxiliary discharge current for each block.

[Problems to be Solved by the Invention] Since the conventional large discharge panel drive circuit is configured as described above, it is necessary to prepare a large number of variable power supply circuits.
It is necessary to adjust the output voltage value of this variable power supply circuit while visually checking the light emitting state of the discharge panel, and when configuring a larger discharge panel display device, the auxiliary anode may also be divided vertically. There were problems such as the need for

This invention was made to solve the above-mentioned problems, and it is a large-sized VC that can stably maintain a predetermined discharge by simply setting an auxiliary discharge current in the vertical direction to a predetermined value. The purpose of the present invention is to provide a discharge panel drive circuit.

[Means for Solving the Three Problems 1] The large discharge panel drive circuit according to the present invention is characterized in that it is configured so that a parabolic control waveform is manually applied to the base of the transistor of the auxiliary anode drive circuit.

[Function 1] According to the present invention, the auxiliary anode drive current changes over time according to the parabolic waveform manually input to the base of the transistor of the auxiliary anode drive circuit, and as a result, the auxiliary anode drive current in the upper and lower peripheral areas is made smaller than in the center. Therefore, the discharge of the entire panel can be maintained at a constant characteristic.

[Embodiment of the Invention] An embodiment of the present invention will be described above based on the drawings.

FIG. 1 is a block diagram of a large discharge panel drive circuit according to an embodiment of the present invention, in which (1) is a discharge panel, (2) is a display anode, (3) is an auxiliary anode, and (4) is a display anode. (5) is a display anode drive circuit, (6) is an auxiliary anode drive circuit, (7) is a cathode drive circuit, and (15) is a constant current control circuit.

2nd [A] is an auxiliary anode drive circuit diagram used in this example, in which (12) is a transistor;
(13) is a current limiting resistor, (E) is a transistor (12
) is the emitter, (B) is the base, and (C) is the collector.

Next, the operation of the above configuration will be explained.

In FIG. 1, the operations of the display anode drive circuit (5) and cathode drive circuit (7) are the same as in the conventional example, and therefore their explanations will be omitted.

The operation of the auxiliary anode drive circuit (6) will be explained based on FIG. 2.

The operation of the transistor (12) in the auxiliary anode drive circuit (8) is the same as in the conventional example;
A constant current control circuit (15) is connected to the base (B) of the constant current control circuit (15), and a parabolic signal is output from this constant current control circuit (15) to drive the transistor (12). Therefore, after the discharge starts, the collector (
The auxiliary discharge current output from the constant current control circuit (1
Similar to the output signal in step 5), it changes in a parabolic manner.

At this time, the output of the constant current control circuit (15) is made to output one parabolic waveform during one vertical scanning period of the discharge panel (1).

In the discharge panel (1), it is often difficult to light up the periphery compared to the center of the panel, but due to the operation northward, the auxiliary anode current in the upper and lower periphery becomes larger than in the center, and the overall discharge in the vertical direction increases. can be kept at a constant property.

In the above embodiment, a case is shown in which a fixed parabolic waveform is used, but the peak value and symmetry of the parabolic waveform may be adjusted depending on the characteristics of the panel.

Further, in the above embodiment, a case where a parabolic waveform is used is shown, but other waveforms may be used depending on the characteristics of the panel.

[Effects of the invention] The auxiliary anode current is controlled by a circuit so that more auxiliary discharge current flows in the periphery than in the center in the vertical direction of the discharge panel, so the discharge panel can be stably driven with a simple configuration. This has the effect that the discharge of the entire large discharge panel can be maintained at a constant characteristic.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a large discharge panel drive circuit according to an embodiment of the present invention, FIG. 2 is a diagram of an auxiliary anode drive circuit used in the embodiment of the present invention, and FIG. 3 is a diagram of a conventional large discharge panel drive circuit. FIG. 4 is a configuration diagram of a discharge panel for explaining an example of a discharge panel, and FIG. 5 is a diagram of an auxiliary anode drive circuit used in a conventional example. ++)--discharge panel, (2)...display anode, (31
-... Auxiliary anode, (4)... Cathode, (51-... Display anode drive circuit, (6)... Auxiliary anode drive circuit, (7)
... Cathode drive circuit, (12) ... Transistor, (
15) Constant current control circuit. Note that the same reference numerals in Figure 1 indicate the same or corresponding parts. show. Surrogate Merada t/＼゛子几图8杹pa gJJ4Se3' 12 Tran/Sta

Claims (1)

[Claims] (1) A discharge panel that displays images using gas discharge, an auxiliary anode formed within this discharge panel, an auxiliary anode drive circuit connected to this auxiliary anode, and a transistor in this auxiliary anode drive circuit. A large-sized discharge panel drive circuit, comprising: a constant current control circuit connected to said constant current control circuit, and an output of said constant current control circuit being a parabolic signal.