JP2000214801A - Plasma address display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prolong the life of a plasma addressed display device by suppressing the amount of discharge electricity. SOLUTION: The plasma address display device has a panel 0 including a display cell provided with a column-shaped signal electrode Y and a plasma cell provided with a row-shaped discharge channel and overlapped with the display cell. The scanning circuit 22 has an output terminal for sequentially applying a selection pulse to the cathode K of the discharge electrodes formed in each discharge channel, and generates charges by ionizing the gas filled in each discharge channel. Thus, line-sequential scanning of each discharge channel is performed. The signal circuit 21 applies an image signal to each signal electrode Y in synchronization with the line-sequential scanning to display a desired image. A capacitor C is provided between each output terminal of the scanning circuit 22 and each corresponding cathode K.
, The amount of charge generated in each discharge channel is independently limited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma addressed display device in which a display cell and a plasma cell are overlapped. More specifically, the present invention relates to a driving circuit configuration of a plasma cell.

[0002]

2. Description of the Related Art A plasma addressed display device is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-265931, and its structure is shown in FIG. As shown, the plasma addressed display device has a flat panel structure including a display cell 1, a plasma cell 2, and a common intermediate sheet 3 interposed therebetween. The intermediate sheet 3 is made of an extremely thin plate glass or the like and is called a micro sheet. The plasma cell 2 is composed of a lower glass substrate 4 bonded to the intermediate sheet 3, and a gas that can be discharged is sealed in a gap between the two. A stripe-shaped discharge electrode is formed on the inner surface of the lower glass substrate 4. Each of these discharge electrodes is an anode A
And functions as a cathode K. Since the discharge electrodes can be printed on the flat glass substrate 4 by a screen printing method or the like, productivity and workability are excellent. A partition wall 7 is formed so as to partition the anode A and the cathode K one by one.
The gap filled with the dischargeable gas is divided to form the discharge channel 5. This partition wall 7 can also be formed by a screen printing method, and the top portion is in contact with one surface side of the intermediate sheet 3. Plasma discharge is generated between the anode A and the cathode K having opposite polarities in the discharge channel 5 surrounded by the pair of partition walls 7. The intermediate sheet 3 and the lower glass substrate 4 are bonded to each other by a glass frit or the like.

On the other hand, the display cell 1 is configured using a transparent upper glass substrate 8. The glass substrate 8 is bonded to the other surface of the intermediate sheet 3 with a sealing material or the like via a predetermined gap, and a liquid crystal 9 is sealed in the gap as an electro-optical material. A signal electrode Y is formed on the inner surface of the upper glass substrate 8. Matrix pixels are formed at the intersections of the signal electrodes Y and the discharge channels 5. The color filter 13 is provided on the inner surface of the glass substrate 8.
Are also provided, and for example, RGB three primary colors are assigned to each pixel. The flat panel having such a configuration is a transmission type,
For example, the plasma cell 2 is located on the incident side, and the display cell 1 is located on the emitting side. Further, a backlight 12 is attached to the plasma cell 2 side.

In the plasma address display device having such a configuration, a row-shaped discharge channel 5 in which plasma discharge is performed is switched in a line-sequential manner and scanned, and an image is applied to a column-shaped signal electrode Y on the display cell 1 side in synchronization with the scanning. Display driving is performed by applying a signal. When a plasma discharge is generated in the discharge channel 5, the inside becomes almost uniformly at the anode potential, and pixel selection is performed for each row. That is, one discharge channel 5 corresponds to one scanning line and functions as a sampling switch. When an image signal is applied to each signal line in a state where the plasma sampling switch is turned on, sampling is performed and lighting or extinguishing of a pixel can be controlled. Even after the plasma sampling switch is turned off, the image signal is held in the pixel as it is. The display cell 1 performs image display by modulating incident light from the backlight 12 into outgoing light in accordance with an image signal.

FIG. 7 is a schematic diagram showing only two pixels cut out. In this figure, only two signal electrodes Y1 and Y2, one cathode K1 and one anode A1 are shown for easy understanding. Individual pixels 11
Are the signal electrodes Y1, Y2, the liquid crystal 9, the intermediate sheet 3
And a discharge channel. The discharge channel is substantially connected to the anode potential during the plasma discharge. When an image signal is applied to each of the signal electrodes Y1 and Y2 in this state, charges are injected into the liquid crystal 9 and the intermediate sheet 3. On the other hand, when the plasma discharge ends, the discharge channel returns to the insulating state, and becomes a floating potential, and the injected charge is held in each pixel 11. A so-called sampling hold operation is performed. Accordingly, since the discharge channel functions as an individual sampling switching element provided in each pixel 11, the switching symbol S
1 is used. On the other hand, the signal electrodes Y1, Y2
The liquid crystal 9 and the intermediate sheet 3 held between the and the discharge channel function as a sampling capacitor. When the sampling switch S1 is turned on by line-sequential scanning, an image signal is written to the sampling capacitor,
Each pixel is turned on or off in accordance with the signal voltage level. Even after the sampling switch S1 is turned off, the signal voltage is held in the sampling capacitor, and the active matrix operation of the display device is performed. Note that the effective voltage actually applied to the liquid crystal 9 is determined by the capacitance division with the intermediate sheet 3.

FIG. 8 is a schematic circuit diagram showing an overall configuration of a plasma addressed display device including peripheral circuits. The plasma address display includes a panel 0, a signal circuit 21, a scanning circuit 22, and a control circuit 23. Panel 0 has a stacked structure in which plasma cells having cathodes K and anodes A arranged in rows and display cells having signal electrodes Y arranged in columns are stacked on each other. The scanning circuit 22 scans the display cells by sequentially applying selection pulses to the cathodes K0 to Kn via a buffer constituting an output terminal. On the other hand, the anodes A0 to An are grounded to the reference potential. The signal circuit 21 supplies an image signal to the signal electrodes Y0 to Ym in synchronization with the above-described scanning,
An image signal is written to each pixel 11. The control circuit 23 controls the synchronization of the signal circuit 21 and the scanning circuit 22.

FIG. 9 shows a selection pulse sequentially applied to each of the cathodes K0 to Kn. For example, when a negative selection pulse is applied to the cathode K1 from the ground level, a plasma discharge occurs between the cathode K1 and the anode A1, and an image signal is written to the corresponding pixel 11.

[0008]

FIG. 10A shows the voltage waveform of the selection pulse applied to the cathode K. At time TF, for example, from the reference potential to -300 to -4.
It changes by 00V and returns to the reference potential at time TR. The pulse width between TF and TR is, for example, about 10 μs.
FIG. 10B shows a waveform of the discharge current flowing through the discharge channel in response to the selection pulse. FIG. 10C shows the waveform of the image signal applied to the signal electrode in synchronization with the selection pulse. When the discharge is completed, the data of the image signal is written to the corresponding pixel. Since the amount of discharge electricity flows according to the width of the selection pulse, deterioration due to discharge appears in a long term, and operation and image quality may be impaired.
The degree of deterioration is substantially proportional to the amount of accumulated discharge current. Therefore, in order to suppress deterioration and extend the life, it is only necessary to make the width of the selection pulse as narrow as possible to reduce the discharge current. However, if the pulse width is simply reduced, the discharge itself becomes unstable, which may cause an operation failure.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the plasma addressed display device according to the present invention is basically formed in each of the display cells provided with the column-shaped signal electrodes, the plasma cells provided with the row-shaped discharge channels, and superposed on the display cells. A scanning circuit that has an output terminal for sequentially applying a selection pulse to the discharge electrodes, and performs a line-sequential scan of each discharge channel by ionizing a gas filled in each discharge channel to generate an electric charge; A signal circuit for applying an image signal to each signal electrode in synchronization with the line-sequential scanning and displaying a desired image. As a feature, by applying a selection pulse by interposing a capacitor between each output terminal of the scanning circuit and each corresponding discharge electrode,
Autonomously limits the amount of charge generated in each discharge channel. Further, the present invention provides a display cell having a column-shaped signal electrode, a plasma cell having a row-shaped discharge channel, and a selection cell in which a selection pulse is sequentially applied to a discharge electrode formed in each discharge channel. A scanning circuit for performing line-sequential scanning of each discharge channel by ionizing the gas filled in each discharge channel to generate electric charge, and synchronizing each signal in synchronization with the line-sequential scanning. In a plasma addressed display device having a signal circuit for applying an image signal to an electrode to perform a desired image display, a capacitor is interposed between each output terminal of the scanning circuit and each discharge electrode corresponding thereto for selection. By applying a pulse, the amount of charge generated in each discharge channel is independently controlled, and a resistance element is interposed between each discharge electrode and the reference potential. Characterized in that to return the respective discharge electrodes after applying a selection pulse to the reference potential by. Alternatively, the present invention provides a display cell including a row of signal electrodes,
A plasma cell having row-shaped discharge channels and an output terminal for sequentially applying a selection pulse to a discharge electrode formed in each discharge channel and a gas filled in each discharge channel are provided. It has a scanning circuit for performing line-sequential scanning of each discharge channel by ionizing and generating electric charges, and a signal circuit for applying an image signal to each signal electrode in synchronization with the line-sequential scanning and displaying a desired image. In the plasma address display device, by applying a selection pulse by interposing a capacitor between each output terminal of the scanning circuit and each discharge electrode corresponding thereto,
Independently limiting the amount of charge generated in each discharge channel and returning each discharge electrode to the reference potential after applying a selection pulse by interposing a diode between each discharge electrode and the reference potential It is characterized by.

According to the present invention, by applying a selection pulse from each output terminal of the scanning circuit to each corresponding discharge electrode via a capacitor, the amount of charge generated in each discharge channel is independently limited. are doing. This allows
The discharge current can be suppressed, and the life can be prolonged without reducing the width of the selection pulse. Further, according to the present invention, by applying a selection pulse from each output terminal of the scanning circuit to each corresponding discharge electrode via a capacitor, the amount of charge generated in each discharge channel can be independently increased. In addition to the limitation, a resistance element or a diode is interposed between each discharge electrode and the reference potential to return each discharge electrode to the reference potential after applying the selection pulse. This ensures that discharge is repeatedly performed in response to the selection pulse.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of a plasma addressed display device according to the present invention.
As shown in FIG.
And a peripheral signal circuit 21, a scanning circuit 22, and a control circuit 23 in addition to the above. The basic configuration of panel 0 is the same as the panel of the conventional plasma addressed display device shown in FIG. That is, the panel 0 is composed of a display cell that modulates incident light into outgoing light in accordance with an image signal and displays an image, and a plasma cell that is surface-bonded to the display cell and performs scanning. The plasma cell has discharge channels arranged in rows, and discharges sequentially to scan display cells line-sequentially. Each discharge channel has a pair of discharge electrodes,
The discharge is driven by the scanning circuit 22. One of the pair of discharge electrodes functions as a cathode K, and the other functions as an anode A. The scanning circuit 22 includes cathodes K0 to Kn
Are sequentially applied to scan the display cells.
On the other hand, the anodes A0 to An are grounded to the reference potential. On the other hand, the display cell has the signal electrodes Y0 to Ym arranged in a column, and the pixel 11 is formed at the intersection with the discharge channel. The signal circuit 21 applies an image signal to each of the signal electrodes Y0 to Ym in synchronization with the line sequential scanning of the discharge channel.
To modulate the incident light for each pixel 11. The control circuit 23 controls the synchronization between the signal circuit 21 and the scanning circuit 22.

As described above, the scanning circuit 22 is provided with an output terminal for sequentially applying a selection pulse to the cathode K of the discharge electrodes formed in each discharge channel. Is ionized to generate charges, thereby performing line-sequential scanning of each discharge channel. As a feature, a selection pulse is applied between each output terminal of the scanning circuit 22 and the cathode K of each discharge channel corresponding thereto via a capacitor C. Thereby, the amount of charge generated in each discharge channel is independently limited. The discharge current can be suppressed, and the life can be extended without reducing the width of the selection pulse.

The operation of the first embodiment shown in FIG. 1 will be described in detail with reference to FIG. FIG. 2A shows a scanning circuit 2.
2 shows a voltage waveform of a selection pulse output from each output terminal of No. 2 and is applied to one electrode of each capacitor C. This voltage waveform is, for example, −
It changes by 300 to -400 V, and returns to the reference potential at time TR. The pulse width between TF and TR is, for example, about 10 μs as in the conventional case.

FIG. 2 (2) shows the waveform of the discharge current flowing through the discharge channel in response to the selection pulse. Almost synchronously with the fall of the selection pulse in the TF, the first discharge occurs, and the discharge current P1 flows. Since the discharge current P1 stops flowing when the capacitor C is charged, the discharge current P1 is shorter than in the conventional case. For example, the capacitor C
The time can be suppressed to about 2 μs by appropriately setting the capacitance of. Subsequently, almost in synchronization with the rise of the selection pulse in TR, a second discharge occurs, and a discharge current P2 flows. Since the discharge current P2 stops flowing when the electric charge charged in the capacitor C is discharged, the discharge current P2 has a shorter time as compared with the related art. By appropriately setting the capacitance of the capacitor C, the time can be suppressed to about 2 μs. Thus, the discharge occurs twice when a relatively light element is selected as the ionizable gas filled in the discharge channel. In the present embodiment, the discharge occurs twice, but the total amount of discharge electricity is smaller than that of the related art,
Accordingly, deterioration of the discharge electrode due to sputtering can be suppressed, and the life can be prolonged. In addition, the power consumption can be reduced.
Although the discharge time is shortened, the width of the selection pulse is sufficiently secured, so that the discharge itself occurs stably even if it occurs before or after some time.

FIG. 2C shows a voltage waveform of each cathode K that changes in response to a selection pulse output from each output terminal of the scanning circuit 22. The voltage appearing at the other electrode of each capacitor C is shown in FIG. It is a change. When the first discharge current P1 flows substantially in accordance with TF, the capacitor C is charged. Therefore, the voltage appearing on the other electrode of the capacitor C shown by the voltage waveform (3) returns from the negative side to the reference potential. Thereafter, the selection pulse returns to the reference potential at TR, so that one electrode potential of the capacitor C also returns to the reference potential. Accordingly, the other electrode potential of the capacitor C rises and largely swings to the positive side, so that a discharge in the opposite direction occurs between the anode A and the discharge current P2. The capacitor C is discharged by the discharge current P2, and the voltage appearing on the other electrode of the capacitor C shown by the voltage waveform (3) returns to the reference potential. As is apparent from the above description, the present embodiment is of the DC drive type in which a DC selection pulse is applied to the cathode K in principle, but actually, the discharge is bidirectional by inserting the capacitor C. It is equivalent to the AC-driven type that occurs once. For convenience of explanation, one of the pair of discharge electrodes is a cathode K,
Although the other is an anode A, the roles are alternated in practice, so that both are similarly subjected to spatter and worn. Therefore, it is preferable to form a sputter-resistant protective film on the surfaces of both discharge electrodes.

FIG. 2D shows the waveform of the image signal applied to the signal electrode in synchronization with the selection pulse. As is apparent from the figure, the data of the image signal is written to the corresponding pixel when the second discharge is completed.

FIG. 3 is a schematic block diagram showing a second embodiment of the plasma addressed display device according to the present invention. Parts corresponding to those of the first embodiment shown in FIG. 1 are given the corresponding reference numerals to facilitate understanding. As in the first embodiment, the scanning circuit 22 has an output terminal for sequentially applying a selection pulse to the cathode K of the discharge electrodes formed in each discharge channel, and the gas filled in each discharge channel is provided. By ionizing to generate electric charge,
Line-sequential scanning of each discharge channel is performed. The selection pulse is applied between the output terminals of the scanning circuit 22 and the cathodes K of the respective discharge channels corresponding thereto by interposing the capacitors C therebetween. Thereby, the amount of charge generated in each discharge channel is independently limited. Discharge current can be suppressed,
It is possible to extend the life without reducing the width of the selection pulse. The difference from the first embodiment is that a resistance element R is provided between each cathode K and a reference potential (ground potential).
Is to return each cathode K to the reference potential after the selection pulse is applied. This allows
Discharge is performed reliably and stably in response to the selection pulse.

The operation of the second embodiment shown in FIG. 3 will be described in detail with reference to FIG. In the first embodiment, since a relatively light element is used as the discharge gas, two discharges are generated with one application of the selection pulse. On the other hand, in the second embodiment, a relatively heavy element is used as the discharge gas, so that one discharge is generated with one application of the selection pulse. FIG. 4A shows a voltage waveform of a selection pulse output from each output terminal of the scanning circuit 22 and is applied to one electrode of each capacitor C. This voltage waveform changes, for example, from the reference potential by −300 to −400 V at time TF, and returns to the reference potential at time TR.
The pulse width between TF and TR is, for example, about 10 μs as in the first embodiment.

FIG. 4B shows the waveform of the discharge current flowing through the discharge channel in response to the selection pulse. In response to the fall of the selection pulse in the TF, a single discharge occurs, and a discharge current P flows. This discharge stops before the discharge current P completely charges the capacitor C.

FIG. 4C shows a voltage waveform of each cathode K which changes in response to a selection pulse output from each output terminal of the scanning circuit 22. The voltage appearing at the other electrode of each capacitor C is shown in FIG. It is a change. When a single discharge current P flows substantially in accordance with TF, the capacitor C is charged. Therefore, the voltage appearing at the other electrode of the capacitor C shown by the voltage waveform (3) goes from the negative side to the reference potential (anode potential). Rise. However, since the capacitor is not completely charged, it does not reach the reference potential. Thereafter, the selection pulse returns to the reference potential at TR, so that one electrode potential of the capacitor C also returns to the reference potential. Accordingly, the potential of the other electrode of the capacitor C rises and swings to the positive level LX. However, this level LX is not high enough to generate the next discharge with respect to the anode potential. That is, no discharge in the reverse direction occurs with the anode A.

By the way, if the potential level of the cathode K remains at LX after the application of the selection pulse is released, the potential difference between the anode and the anode is reduced by LX in the next field when the selection pulse is applied again. Therefore, no discharge occurs. In order to solve this, in the present embodiment, a resistance element R is connected to the capacitor C, and the capacitor C
Is released until the next field to lower the potential of the cathode from LX to the reference potential L.
Thus, even in the next and subsequent fields, the discharge is reliably and stably repeated in response to the selection pulse.
Assuming that the field frequency is 60 Hz, the circuit may be designed so that the time constant of the circuit constituted by the capacitor C and the resistance element R is between the selection pulse width of 10 μs and the field period of about 17 ms. For example, the capacitance value of the capacitor C is set to about 2000 pF, and the resistance value of the resistance element R is set to about 30 kΩ. Unlike the first embodiment, this embodiment is a complete DC drive type, and the discharge current flows in only one direction, so that the configuration of the scanning circuit is simplified. Further, it is sufficient to form a protective film for spatter resistance only on the original cathode, and it is not necessary to form a protective film on the discharge electrode on the anode side.

FIG. 4 (4) shows the waveform of the image signal applied to the signal electrode in response to the selection pulse. As is clear from the figure, the data of the image signal is written to the corresponding pixel at the time when the single discharge ends.

FIG. 5 is a schematic block diagram showing a third embodiment of the plasma addressed display device according to the present invention. Parts corresponding to those of the second embodiment shown in FIG. 3 are denoted by corresponding reference numerals to facilitate understanding. The difference from the second embodiment is that diodes D are interposed between each cathode K and a reference potential (ground potential), whereby each cathode K is quickly returned to the reference potential after application of the selection pulse. . Thus, similarly to the second embodiment, the discharge is reliably and stably repeated in response to the selection pulse.

As described above, according to the present invention,
In a flat panel constituting a plasma addressed display device, by applying a selection pulse from each output terminal of a scanning circuit to each corresponding discharge electrode via a capacitor, the amount of charge generated in each discharge channel can be independently controlled. Limited to As a result, the amount of discharged electricity can be suppressed, and the life can be extended without reducing the width of the selection pulse. Further, a resistance element or a diode may be interposed between each discharge electrode and the reference potential. Thus, by returning each discharge electrode to the reference potential after the application of the selection pulse, the discharge is reliably performed repeatedly in response to the selection pulse.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a first embodiment of a plasma addressed display device according to the present invention.

FIG. 2 is a waveform chart for explaining the operation of the plasma addressed display device shown in FIG.

FIG. 3 is a schematic plan view showing a second embodiment of the plasma addressed display device according to the present invention.

FIG. 4 is a waveform chart for explaining the operation of the plasma addressed display device shown in FIG. 3;

FIG. 5 is a schematic plan view showing a third embodiment of the plasma addressed display device according to the present invention.

FIG. 6 is a sectional view showing an example of a conventional plasma addressed display device.

FIG. 7 is a schematic diagram for explaining the operation of the conventional plasma addressed display device shown in FIG.

8 is an overall configuration diagram of the conventional plasma addressed display device shown in FIG.

FIG. 9 is a timing chart for explaining the operation of the entire configuration of the conventional plasma addressed display device shown in FIG.

FIG. 10 is a waveform chart for explaining the operation of the conventional plasma addressed display device shown in FIG.

[Explanation of symbols]

0 ... panel, 1 ... display cell, 2 ... plasma cell, 5 ... discharge channel, 7 ... partition wall, 9 ...
Liquid crystal, 11 pixels, 12 backlight 21
..Signal circuit, 22 ... Scan circuit, K ... Cathode, A ... Anode, C ... Capacitor, R ...
Resistance element, D ... diode

Claims (3)

[Claims] 1. A selection pulse is sequentially applied to a display cell provided with a column-shaped signal electrode, a plasma cell provided with a row-shaped discharge channel, and a discharge cell formed in each discharge channel. A scanning circuit for performing line-sequential scanning of each discharge channel by ionizing gas filled in each discharge channel to generate electric charges, and each signal electrode in synchronization with the line-sequential scanning And a signal circuit for applying an image signal to display a desired image by applying a selection pulse by interposing a capacitor between each output terminal of the scanning circuit and each discharge electrode corresponding thereto. Wherein the amount of charge generated in each discharge channel is independently controlled by applying a voltage. 2. A selection pulse is sequentially applied to a display cell having a column-shaped signal electrode, a plasma cell having a row-shaped discharge channel and superposed on the display cell, and a discharge electrode formed in each discharge channel. A scanning circuit for performing line-sequential scanning of each discharge channel by ionizing gas filled in each discharge channel to generate electric charges, and each signal electrode in synchronization with the line-sequential scanning And a signal circuit for applying an image signal to display a desired image by applying a selection pulse by interposing a capacitor between each output terminal of the scanning circuit and each discharge electrode corresponding thereto. By applying a voltage, the amount of charge generated in each discharge channel is independently controlled, and a resistance element is interposed between each discharge electrode and the reference potential. The plasma addressed display device characterized by returning the respective discharge electrodes after applying a selection pulse to the reference potential by. 3. A selection pulse is sequentially applied to a display cell having column-shaped signal electrodes, a plasma cell having row-shaped discharge channels, and a discharge cell formed in each discharge channel. A scanning circuit for performing line-sequential scanning of each discharge channel by ionizing gas filled in each discharge channel to generate electric charges, and each signal electrode in synchronization with the line-sequential scanning And a signal circuit for applying an image signal to display a desired image by applying a selection pulse by interposing a capacitor between each output terminal of the scanning circuit and each discharge electrode corresponding thereto. , The amount of charge generated in each discharge channel is independently controlled, and a diode is interposed between each discharge electrode and the reference potential. The plasma addressed display device, characterized in that to return to the reference potential to each of the discharge electrodes after applying a selection pulse by the.