JPS6217346B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an external electrode type discharge display panel, a so-called plasma display panel.

This type of plasma display panel consists of three thin, flat glass plates laminated together.The central glass plate has a plurality of small holes perforated at predetermined positions. The surrounding area is hermetically sealed between outer glass plates, and the inside is evacuated and filled with inert gas such as neon. On the outer surface of each outer glass plate,
Electrodes, so-called matrix electrodes, are formed that pass directly above each hole of the central perforated plate and are orthogonal to each other, and a high-frequency voltage is selectively applied between the matrix electrodes corresponding to the characters or symbols to be displayed. By applying this voltage, the gas in the small hole of the central perforated plate is discharged, and the desired character or symbol is displayed by the light emission.

As an improved version of the conventional plasma display panel having such a structure, the two outer glass plates are made of thick glass plates, electrodes are formed on the inner surfaces of the two outer glass plates, and a thin dielectric film such as a glass film is formed on the electrodes. Those coated with are in practical use. In addition, plasma display panels in which the central glass plate is removed and plasma display panels that have segment electrodes exclusively for displaying numbers instead of the matrix electrodes described above have also been proposed.

In any of these panels, if a DC voltage higher than the discharge starting voltage is applied to the gas space (this will be called a cell) defined by a pair of opposing external electrodes using the opposing external electrodes, the cell will Start discharging. (However, it is assumed that the voltage drop due to the dielectric film can be ignored.) However, when the cell starts discharging, the dielectric film interposed between the electrode and the cell is charged by the charged particles generated by the discharge, and the electric field inside the cell is When the intensity is lowered and the sum of the externally applied voltage and the reverse voltage due to charging of the dielectric film becomes smaller than the discharge sustaining voltage of the cell, the discharge automatically stops. Next, when the polarity of the DC voltage applied to the pair of opposing external electrodes is reversed, the externally applied voltage and the voltage due to charging of the dielectric film will have the same polarity, and the voltage applied to the cell will be higher than the discharge starting voltage. It goes high and then stops after discharging again. By repeating these operations, that is, by sequentially applying voltages with different polarities between opposing external electrodes, intermittent discharge can be sustained, and the number of repetitions of intermittent discharge per unit time can be adjusted appropriately. If set (for example, 10,000 times per second), sufficient brightness for display can be obtained.

As a method of driving an external electrode type discharge display panel having such characteristics, a pulsed voltage is selectively applied to either the row electrode group or the column electrode group, and when the other electrode group is selected, the DC power supply voltage is applied to the other electrode group. A driving method has been proposed in which the voltage is fixed to Vo or the earth potential (grounded) and opened when not selected.

A circuit using transistors has been proposed as a simple circuit configuration for realizing this driving method. Now suppose that a pulsed voltage of amplitude Vo is applied to the row electrodes (in this case, Vo must be greater than the value at which all cells in the display panel discharge and emit light).On the other hand, the column electrodes opposite to this must be When the electrode is not selected, the transistor of the circuit corresponding to the electrode is in the off state, and when the electrode is selected, the transistor of the circuit corresponding to the electrode is in the on state. Become. In such a drive circuit, if some adjacent column electrodes are in a selected state when the current column electrode (this is called Rk) is not selected, the column due to the capacitance in the display board Due to coupling between electrodes or coupling due to stray capacitance of wiring, if the sum of these capacitances is C and the cell capacitance is C', the voltage induced in column electrode Rk is
Vi is (1) Vi=C'/C+C'·Vo, and the larger the value of Vi, the wider the operating range.

This phenomenon will be explained in detail with reference to the drawings.

FIG. 1 shows pulse voltage waveforms applied to electrodes when driving an external electrode type discharge display panel in a time division manner. In this time-division driving, the row electrodes are
As shown in b and c, a pulsed voltage of amplitude Vo, repetition t, and pulse width Pw is generated for T time, and the time during which the pulse is generated is shown in the first line, second line,...
..., allocate T time each corresponding to the n-th row electrode.
It is refreshed (repeated) at a period of nT, and when a pulse is applied to each row, the m-th column electrode corresponding to the cell to be ignited is brought to ground potential (or Vo) as shown in Figure 1d. Fix it and
Display is performed by selectively discharging and igniting only the necessary cells.

For example, apply the voltages shown in Figure 1 a, b, and c from the first row electrode to the third row electrode, and
If the refresh is performed at a cycle of nT and the m-th column electrode is fixed at the ground potential as shown in Figure 1 d, the voltage applied to the cell (1st row, m column) will be as shown in Figure 1 e. Therefore, the voltage applied to (2nd row, mth column) is as shown in FIG. 1f. Here, pulse 1 is a voltage induced in the m-th column electrode because the m-th column electrode is not selected. In the time-division driving method, it is necessary to select the value of the DC power supply voltage Vo so that only cells whose row electrodes and column electrodes are selected at the same time are discharged, and no discharge occurs when only one electrode is selected. Now, with all cells of one external electrode type discharge display board selected, increase the power supply voltage Vo, set the voltage value when all cells are lit as Vfmax, and conversely decrease Vo to all Let the voltage value when the cell turns off be Vsmin. Vo≧Vfmax is required in order to ensure that when any row electrode and column electrode are selected, the cell at the intersection is lit. Further, in order for the cell not to light up when only either the row electrode or the column electrode of an arbitrary cell is selected, Vo<Vsmin+Vi is required.
Here, Vi is the pulse voltage when the column electrode is not selected.
This is the voltage induced in the column electrode by Vo.

Therefore, when driving the display board, the permissible range of the DC power supply voltage Vo must be (2) V _fnax. ≦ _Vo < V _snio + _Vi .

That is, the larger the value of Vi, the wider the operating range of the display panel, while the smaller the value of Vi, the narrower the operating voltage range of the display panel. The induced voltage Vi that appears when not selected is the smallest when the adjacent column electrode is selected, for example + several V
However, the range of power supply voltage required for normal operation of the display board was very narrow, which caused a practical problem. In order to increase the magnitude of this induced potential, it is possible to reduce C and increase C', but it is possible to reduce C and increase C'. There is a limit to the structure in which rare gas is sealed within the cell, and a solution to this problem has been long awaited.

A method has also been proposed in which a pulse voltage synchronized with the pulse applied to the row electrodes is forcibly applied to unselected column electrodes from an external circuit, but this method has the disadvantage that the external circuit becomes expensive.

An object of the present invention is to increase the operating voltage range of a display board without changing the circuit configuration and without causing erroneous display even in a circuit configuration where erroneous display occurs due to a decrease in the induced potential due to capacitive coupling. It is an object of the present invention to provide an external electrode discharge display panel that can be used widely.

According to the present invention, a first substrate having a plurality of first electrode groups and a second substrate having a plurality of second electrode groups facing each other are made to face each other, and a frit glass is placed between the two substrates in a sandwich-like configuration. In an external electrode type discharge display board which is formed by sandwiching and hermetically sealing, the first and second electrodes are opposed to each other in the hermetic sealing frit glass part to form a capacitor, and the above-mentioned C' Increase the value of
Accordingly, a display board having a structure that increases the value of Vi can be obtained. Specifically, for example, a row electrode and a lead wire for supplying a pulse voltage to the electrode are integrally formed on one of the glass plates, and a line opposite to the lead wire portion is formed on the other glass plate. to form an electrode with a large area. The gap is filled with frit glass for airtight sealing to form a capacitor.

At this time, the fritted glass for airtight sealing is
It also functions as a dielectric for a capacitor. Further, the electrodes having a large area and the column electrodes are connected within the panel using lead wires or the like. In an external electrode type discharge display panel having such a structure, since the C' value in equation (1) can be increased, the induced voltage Vi can be increased, and the operating voltage range of the display panel can be expanded.

A first embodiment of the present invention will be described with reference to FIGS. 2 and 3.

On the rear glass plate 6 having the exhaust hole 10,
The column electrode group 8 and the electrode group 7, which has a large area and is one electrode of the capacitor, are connected to each other and are integrally formed by printing. At this time, the electrode group 7 is
It is formed at the end of the glass plate 6. A dielectric film 9 is formed on the column electrode group 8 . On the front glass 2, the electrode group 8 and the electrode group 7 on the opposing rear glass plate 6 and the electrode group (row electrode) 3 are formed to face each other. Furthermore, the dielectric film 4 is attached to the electrode group 7.
The electrode group 3 is coated with the electrode group 3 other than the portion facing the electrode group 3. A frit glass 5 for airtight sealing is formed in the shape of a hole frame on one or both of the glass plates 2 and 6 so as to cover the electrode group 7 and not to cover the display area. These electrode group 7 and electrode group 3
They are successively stacked one on top of the other so that they alternately face each other, are pressed and fired in an electric furnace, and are hermetically sealed. FIG. 3 is a sectional view of the display board at that time. The electrode group 3 and the electrode group 8 form a display cell, and the electrode group 3 and the electrode group 7 form a capacitor whose dielectric is fritted glass filled in the gap therebetween. Finally, the exhaust pipe 11 is attached to the hole 10, and gas, for example, Ne, is filled in several hundred torr through the exhaust pipe 11 into the resulting display board.

For example, if the amplitude is applied to the electrode group 3 on such a display board,
A pulse voltage of 280 V and a frequency of 400 kHz is sequentially applied in a time-division manner, while the electrode group 8 is operated by being grounded or disconnected by a switch circuit. In this display board, the capacitor formed in the sealing frit glass part increases the C' value in equation (1), making it possible to widen the voltage range for normal operation of the display board.

According to this embodiment, a capacitor can be formed very easily and economically by using hermetic sealing and fritted glass which also serves as a dielectric.Moreover, the dielectric constant of fritted glass is several times larger than that of Ne gas. Therefore, it is possible to form a capacitor with a large capacitance in a relatively small area. In this way, the display board according to the present invention, which has realized the increase in the value of C' in equation (1), can increase the operating voltage range without changing the circuit configuration, which previously could only accommodate an operating range of 10V. I was able to make it 50V.

To give a more specific example, for example, in a conventional panel with 20 characters and one line having a 5×7 dot format with a dot pitch of 2 mm and a dot size of 1.5 mm, C' = 0.5 pF and C = 10 pF. Therefore, the induced voltage Vi is 280×{0.5/(10+
0.5)} = 13.3V. In Fig. 2, which shows an embodiment of the present invention, a counter electrode portion having the same area as the display cell with frit glass having a dielectric constant of 10 in between is shown. If C′〓(0.5+5)pF C〓(10+10)pF, the induced voltage Vi will be 280×{5.5/(20+5.5)}=60.4V, and Vi will increase dramatically.

In general, the dimensions of the capacitor section, which is a feature of this application, must be designed based on the dimensions of the display section of the panel, etc.
In addition, as a frit glass material, relative permittivity ε=10
It is possible to select and use ~40 ones.

Still another embodiment is shown in FIG.

On the rear glass plate 17 are a column electrode group 19 and an electrode group 18 with a wider width that becomes one electrode of the capacitor.
Formed by printing. A dielectric film 20 is formed on the electrode group 19. Hole 21 is an exhaust hole. An electrode group 14 (row electrode) is formed on the front glass plate 12 so as to face the electrode group 19 on the opposing rear glass plate 17, and a wide electrode 13 is formed so as to face the electrode group 18. form.
Next, the dielectric film 15 is coated on the electrode group 14, and the hermetic sealing frit glass 16 is placed in the shape of a hole frame on one or both of the front glass plate 12 and the rear glass plate 17 so as to cover the electrode group 18, respectively. Form. These are stacked one on top of the other, pressed and fired in an electric furnace, and hermetically sealed. The electrode group 19 and the electrode group 14 form a display cell, and the electrode group 18 and the electrode 13 form a capacitor whose dielectric is fritted glass filled in the gap therebetween. Finally exhaust pipe 2
2 into hole 21, and attach the completed display board to exhaust pipe 2.
From 2, a gas such as Ne is sealed in several hundred torr.
On such a display board, for example, an amplitude is applied to the electrode group 14.
A pulse voltage of 280 V and a frequency of 400 kHz is applied sequentially in a time-division manner, while the electrode group 19 is grounded or released by a switch circuit. A pulse voltage of the same polarity (amplitude is, for example, 280V) that is synchronized with the pulse voltage applied to the electrode group 14 is constantly applied to the electrode 13. In a display panel having such a configuration, the electrode 1
Although one circuit is required to constantly apply a pulse to 3, it requires almost no space to form a capacitor.For example, if the horizontal length of the display board is increased by 1 cm to 2 cm, This is sufficient to form a capacitor with a capacitance of + several pF. In this way, the present display board can expand the operating voltage range to a value that does not pose a problem for practical use, without changing the size of the display board.

As shown in Examples, FIGS. 2, 3, and 4, according to the present invention, hermetic sealing and capacitor formation can be performed simultaneously by using a frit glass for hermetic sealing having a large dielectric constant. This makes it possible to obtain a display panel with a wide operating voltage range in an extremely simple and economical manner.

[Brief explanation of the drawing]

FIG. 1 shows the time-division driving voltage waveform of the external electrode type discharge display panel, and FIG. 2 shows the first waveform of the display panel according to the present invention.
FIG. 3 is an exploded perspective view showing an embodiment of the present invention, and FIG. 3 is a sectional view thereof. FIG. 4 is an exploded perspective view showing a second embodiment of the display board according to the present invention.

Claims (1)

[Claims] 1. A first substrate having a plurality of first electrodes to which a pulse voltage is selectively applied, and a second substrate opposite thereto having a plurality of second electrodes which are selectively grounded or fixed to an arbitrary DC voltage level. In an external electrode type discharge display board formed by sandwiching frit glass between the two substrates in a sandwich-like manner and sealing them airtightly, the extended portion of the second electrode is placed opposite to each other with a discharge gas in between, and the extended portion of the second electrode is hermetically sealed. The first electrode may extend into the fritted glass portion and extend into the fritted glass portion, with each extension sandwiching the fritted glass portion, or the first electrode may be attached to the first substrate. A third electrode is provided to which a pulse voltage is constantly applied, and the third electrode is extended into the fritted glass portion, and the fritted glass portion is sandwiched between the extended portion of the second electrode. Features an external electrode type discharge display board.