JPS644145Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a display device using an AC type plasma display panel (hereinafter abbreviated as PDP).

The PDP narrows the dischargeable gas medium and faces each other,
It consists of two sets of electrodes arranged in a matrix, the surface of each electrode in contact with the gas medium is covered with a dielectric layer, and the externally applied voltage is coupled with the gas medium via a capacitance. Therefore, the gas cell is narrowed between a pair of opposing electrodes that intersect with each other.
By applying an AC voltage, each time the polarity of the applied voltage changes, a discharge is caused intermittently in the cell, allowing it to emit light.

In order to drive this type of PDP using the time division method,
First, a voltage pulse train consisting of a plurality of pulses is sequentially applied to each electrode in one of the electrode groups in opposing rows or columns, and scanning is performed at a repetition rate of about 60 times or more per second.

When a voltage pulse train is applied to a certain electrode among these electrodes, that is, in a selected state, all of the gas cells in a row determined by this electrode, which determine the cells to be emitted according to the display data contents, By applying a pulse train having an opposite phase to the above pulse train to the opposing electrodes to bring it into a selected state, only desired cells can be caused to discharge and emit light. By repeating the above operation each time each electrode in the former electrode group is scanned, a desired display can be obtained on the entire surface.

Next, an example of a conventional circuit configuration of a device using this type of PDP will be explained using drawings.

FIG. 1 is a diagram showing a conventional circuit configuration.

Figure 1a is a comprehensive block diagram, and the first
Figure b is a diagram showing the toggle generator, and the first
FIG. c is a diagram showing the configuration of one circuit of a row driver and a column driver.

The operation of the circuit configuration in FIG. 1 will be briefly explained.

In Figure 1a, the toggle generator is
This circuit generates high-frequency pulses with voltage amplitude sufficient to discharge each cell of a PDP. The configuration of the toggle generator is shown in FIG. 1b. Here, the primary winding 11 of the transformer 1 and the feed bag winding 1
2, the transistor 2, and additional resistors and capacitors together constitute a general blocking oscillation circuit, which oscillates at a frequency determined mainly by the inductance and stray capacitance of the primary winding 11. Therefore, although a voltage is induced in the secondary winding 13 due to the current change in the primary winding 11,
Since the center tap of No. 3 is grounded, alternating current voltages of opposite phases are obtained at both ends 14 and 15, respectively, that is, voltages swinging between a certain positive potential and a negative potential. The voltage at one end 14 of the secondary winding is connected to a series capacitor 3 and a clamp diode 5.
The level is shifted to the positive side, and a pulse voltage swinging between the ground potential and a certain positive potential is obtained at the output -1 terminal. Other end of secondary winding 1
The same goes for voltage No. 5, and a voltage that swings between the ground potential and a certain positive potential is obtained at the output-2 terminal, and this is in the opposite phase to the pulse voltage obtained at the output-1 terminal. .

By the way, if the power supply voltage is 12V, if the turns ratio of the primary winding and secondary winding is about 1:25, the output will be -1
The amplitude of the pulse voltage appearing at the output-2 terminal is about 150V, which is suitable for use as a row toggle generator and a column toggle generator in a plasma display panel. Furthermore, the power supply voltage is
Even in cases other than 12V, by adjusting the primary and secondary turns ratio, it is possible to always obtain the optimum pulse voltage to drive the plasma display panel. The pulse voltages output by these toggle generators are supplied to all drivers. That is, output 1 is supplied to all row drivers and output 2 is supplied to all column drivers.

Each driver has an input end and an output end.
It is configured to perform a gate operation to determine whether or not to pass the pulse voltage supplied from the toggle generator to the output terminal depending on the logic level of TTL, C-MOS, etc. applied to the input terminal. Therefore, the output of each driver is controlled by appropriately applying the output of the logic circuit to the input terminal of each driver.
Each cell on the PDP can be selectively displayed. However, a PDP consists of two sets of electrodes arranged in a matrix, facing each other with a dischargeable gas medium in between, and the surface of each electrode in contact with the gas medium is covered with a dielectric layer, so that no external voltage can be applied. The voltage is configured to be coupled to the gas medium via the capacitance. Therefore, a voltage pulse train is sequentially applied to the column electrodes among these electrodes, that is, when in the selection state, among the gas cell group in one column determined by this electrode, all the opposite cells that are to be emitted according to the display data contents are applied. When a high voltage pulse is applied to the row electrodes, the state of coupling with the gas medium changes, so the load on the toggle generator supplied to each driver in the matrix changes, and the oscillation frequency of the blocking oscillator changes. That is, the number of discharges of the PDP is affected depending on the contents of the display data, resulting in a drawback that the luminance of the PDP changes.

The purpose of this invention is to provide a PDP that eliminates these drawbacks.
An object of the present invention is to provide a toggle generator used in a display device.

The present invention relates to a device using a plasma display, and includes a blocking oscillation circuit comprising a transformer having at least one primary winding and one feedback winding, and at least one transistor, wherein the transformer further has a center The center tap is grounded, and the plasma display panel is connected to the ground potential in opposite phases to each other through a series capacitor and a clamp diode from both ends of the secondary winding to the ground potential. a blocking oscillator circuit configured to obtain two pulse voltages swinging between a positive potential and a positive potential capable of lighting up the secondary winding; and two capacitors each connected between both ends of the secondary winding and ground potential. This purpose was achieved by combining the following.

FIG. 2 shows an embodiment of the present invention.

In Fig. 2, the primary winding 11, feedback winding 12, transistor 2, and additional resistors and capacitors of the transformer 1 constitute a blocking oscillator circuit similar to that shown in Fig. 1a, which oscillates at a frequency determined mainly by the inductance of the primary winding 11, the stray capacitance, and the secondary side _capacitive load.
If the input voltage is 12V, the turns ratio of the primary and secondary windings should be 1
If the number of pairs is about 25, a current of sufficient amplitude (approximately 150/150/250) to discharge the PDP will be generated at both ends 14 and 15 of the secondary winding.
150V) were obtained, and the PDP
It can be fully applied as a toggle generator.

On the other hand, among the elements that determine the oscillation frequency of the blocking oscillator, the secondary side capacitive load is determined as the sum of dummy capacitors 7 and 8 and the capacitance of the PDP, so it changes depending on the content of the display data of the PDP. PDP capacity fluctuations are less likely to affect the toggle generator.

The capacitance fluctuation of the PDP, which changes depending on the content of display data, depends on the size of the cell consisting of opposing row and column electrodes of the PDP, the pitch of the row and column electrodes, the way the lead wires are routed, etc. The column pitch of the PDP is 0.5 mm, the cell size is 2.54 x 0.25 mm, the number of row electrodes is 20, the number of column electrodes is 20, and the total number of cells is 400. When inputting any display data up to full screen display
The capacitance variation range of PDP is approximately 200pF to 500pF.
Therefore, the capacitance values of the dummy capacitors 7 and 8 should be such that the difference in luminance of the PDP does not pose a problem within the range in which the blocking oscillation circuit operates stably.
In other words, the value where the fluctuation of the sum of the dummy capacitor and PDP capacitance is within about 30%, 500pF ~
It can be determined between 3000pF.

As is clear from the examples above, by applying the present invention, there is less variation in the oscillation frequency of the toggle generator supplied to each driver in the matrix depending on the display data content, and as a result, the luminance of the PDP changes. A plasma display device with high display quality can be realized.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a conventional circuit configuration of a device using a plasma display panel, Fig. 1a is its comprehensive block diagram, and Fig. 1b shows a circuit of a row toggle generator. 1c is a diagram illustrating one circuit of a row driver and a column driver, and FIG. 2 is a diagram illustrating an embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] A transformer having at least one primary winding and one feedback winding, and at least one transistor, the transformer further comprising a secondary winding having a center tap, the center tap being grounded. and from each end of the secondary winding through a series capacitor and a clamp diode to ground potential, two pulsed voltages swinging between ground potential and a positive potential capable of lighting the plasma display panel, in opposite phases to each other. 1. A plasma display device comprising: a blocking oscillation circuit configured to obtain a blocking oscillation circuit; and two capacitors each connected between both ends of the secondary winding and a ground potential.