JPH11202305A - Picture display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of electrodes disposed inside the discharge channel of a picture display device and to improve the opening ratio of the discharge channel. SOLUTION: This device is provided with a liquid crystal panel 3 provided with many address electrodes 10 arrayed in a columnar shape, a first glass substrate 2 facing the liquid crystal panel 3 parallel at prescribed opposing intervals so as to constitute a discharge space part 5, many discharging electrodes 6 which constitutes many mutually parallel discharge channels 11 for diving the discharge space part 5 and is provided to be arrayed in a row shape orthogonal to the address electrodes 10 on the main surface of the first glass substrate 2, a control part constituted of many switches SW for respectively controlling the supply and interruption of a driving voltage with respect to the electrodes 6 and a line scanning circuit for supplying selection pulses for sequentially opening and closing the respective switches SW of the control part by line progressive scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image display device, and more particularly to a plasma addressed liquid crystal display device used in the technical field of a flat panel image display device.

[0002]

2. Description of the Related Art Conventionally, as a means for achieving higher resolution and higher contrast in an image display apparatus, a method has been used in which an active element such as a transistor is provided for each display pixel and the active element is driven. However, such an image display device requires a semiconductor element such as a thin film transistor to be provided for each display pixel, so that there is a problem that the cost increases when the screen is enlarged. Therefore, as a means for solving the above problem, a plasma addressed liquid crystal display (PAL) that performs switching by using plasma discharge instead of a semiconductor element to drive a liquid crystal is provided as a means for solving the above problem.
C) has been proposed.

Hereinafter, the configuration of the PALC will be briefly described.
The PALC 100 is, as shown in FIG.
1, a first transparent glass substrate 103 arranged in parallel and opposed to the liquid crystal panel 101 and the discharge space 102, and a backlight 104. The liquid crystal panel 101 includes a second transparent glass substrate 105
And a thin dielectric sheet 106 made of glass or the like, and a liquid crystal layer 107 as an electro-optical material substrate.
On the second transparent glass substrate 105, a large number of transparent electrodes 108 arranged in parallel with each other are formed on the main surface 105a on the liquid crystal layer 107 side. The liquid crystal layer 107 is sandwiched between the second transparent glass substrate 105 and the dielectric sheet 106.

On a first transparent glass substrate 103, a large number of anode electrodes 109 and cathode electrodes 110 are provided on a main surface 102 a on the liquid crystal panel 101 side in a direction parallel to each other and orthogonal to a transparent electrode 108. ing.

The discharge space 102 is formed in a space facing the liquid crystal panel 101 and the first transparent glass substrate 103. The discharge space 102 is filled with a discharge gas capable of being ionized. In addition, the discharge space 102
The inside is divided by the anode electrode 109 into a number of discharge channels 111 corresponding to the scanning lines. The discharge channel 111 is connected to the transparent electrode 1 of the liquid crystal panel 101.
08 are formed in a direction perpendicular to the direction 08, and these intersections correspond to each pixel. Also, the discharge channel 11
1, the anode electrode 109 and the cathode electrode 1
When a drive voltage based on the display screen is applied to 10, the discharge gas sealed in the discharge space 102 is ionized to generate plasma discharge.

[0006] The PALC 100 having the above-described configuration has:
By applying a drive voltage based on a display image to the cathode electrode 110, the cathode electrode 1 to which the drive voltage is applied
A plasma discharge is generated in a discharge channel 111 formed between the liquid crystal layer 107 and the anode electrode 10 adjacent to the cathode electrode 110 and the anode electrode 109 adjacent to the cathode electrode 110.
9 is conducted. The PALC 100 sequentially switches and scans the discharge channel 111 where the plasma discharge occurs, and applies a signal voltage to the transparent electrode 108 in synchronization with the drive voltage, whereby the signal voltage is held in each pixel, and the liquid crystal layer 107 is driven. Is done.

Hereinafter, a liquid crystal drive circuit provided in PALC 100 will be described. The liquid crystal drive circuit is turned on and off by the timing pulse generator 112 as shown in FIG.
Switch section 113 to which an OFF timing pulse is given
A power supply device 114 serving as a power supply for the drive voltage; a control device 115 for controlling the supply of the drive voltage;
0, an anode electrode 109 and a discharge channel 111.
Switch unit 113 to correspond to the cathode electrode 110 which has the same number of switches SW ₁ to SW _n and the cathode electrode 110, each of the switches SW ₁ through SW _n is constituted by normally closed contact 113a and the normally open contacts 113b . Plasma discharge device 116, the anode electrode 109 while being commonly connected to the power supply 114, a cathode electrode 110 is connected to the corresponding switches SW ₁ to each power supply 114 through a SW _n of the switch unit 113. The corresponding switch SW ₁ is connected to the cathode electrode 110.
To the timing pulses given to the SW _n, contacts (not shown) was connected to the normally closed contact 113a is a driving voltage is connected to the normally open contact 113b side is applied.

[0008] PALC100, as shown in FIG. 6, by the timing pulse on and off is applied to each of the switches SW ₁ through SW _n of the switch unit 113, sequential driving voltage is applied to the cathode electrodes 110 . That is, in the PALC 100, the switch S
W ₁ to be to connect to the normally open contacts 113b each sequential one horizontal period to SW _n, each discharge channel 111 is selected once in one field, the plasma discharge is generated.

As described above, in the conventional PALC 100, in order to generate a plasma discharge in the discharge channel 111, the two electrodes of the cathode electrode 110 and the anode electrode 109 are used.
Seed electrodes were disposed in the discharge channel 111.

[0010]

The above-described conventional PALC 100 has the following problems. That is, the PALC 100 is the cathode electrode 1
10 and an anode electrode 109 are disposed in the discharge channel 111 to perform an image display by performing an optical shutter function.
Is formed of an opaque material, which causes a problem that the aperture ratio of the discharge channel 111 is reduced. Further, in the PALC 100, since the cathode electrode 110 and the anode electrode 109 absorb or reflect the irradiation light emitted from the backlight 104, there is a problem that the transmittance of the reflected light is reduced and the brightness of the display image is small. .

In the PALC 100, when the brightness of the backlight 104 is increased in order to ensure a high brightness of a displayed image, heat generation of a lamp or a circuit increases, and components used need to have high reliability. Therefore, there is a problem that the cost is increased. Also, PALC10
In the case of 0, the cathode electrode 110 and the anode electrode 109 must be formed of a metal film in order to cope with the occurrence of a sputtering phenomenon due to the plasma discharge. Therefore, in the PALC 100, for example, it is not possible to improve the aperture ratio of the discharge channel 111 by forming these electrodes with a transparent material. Furthermore, PALC1
00, the cathode electrode 110 and the anode electrode 10
In the case where the stripe width of No. 9 is reduced, the cathode electrode 110 and the anode electrode 109 may be disconnected at the time of manufacture or operation, so it is necessary to secure a certain width dimension.

The present invention has been proposed to solve the above-mentioned problems of the conventional image display device and to provide an image display device having an improved discharge channel aperture ratio.

[0013]

According to the present invention, there is provided an image display apparatus comprising: a liquid crystal panel provided with a plurality of address electrodes arranged in a row; Accordingly, the glass substrate constituting the discharge space portion by being arranged in parallel and facing each other, and on the main surface of the glass substrate, are arranged in a row orthogonal to the address electrodes and are parallel to each other to divide the discharge space portion. A control unit composed of a large number of discharge electrodes constituting a large number of discharge channels, a large number of switches for controlling supply and cutoff of a drive voltage to each discharge electrode, and each switch of the control unit is scanned in a line-sequential manner. A line scanning circuit for supplying a selection pulse for sequentially opening and closing.

According to the image display apparatus of the present invention configured as described above, the predetermined discharge electrode whose potential is changed by the opening operation of the predetermined switch of the control unit selected by the selection pulse, and the discharge electrode When the potential of the discharge electrode immediately before the discharge electrode is the same as that of the discharge electrode, a plasma discharge is generated in a discharge channel formed between the discharge electrodes, and the plasma discharge is generated by the plasma discharge. Is performed to drive the liquid crystal to display an image. Therefore, according to the image display device of the present invention, it is not necessary to dispose two kinds of electrodes, ie, an anode electrode and a cathode electrode in each discharge channel, and the number of electrodes in the discharge channel is reduced. And the amount of transmitted light emitted from the backlight increases, thereby improving the brightness of the displayed image, thereby improving the image quality.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of an image display device according to the present invention will be described in detail with reference to the drawings. Image display device 1 shown as an embodiment
Is a plasma addressed liquid crystal display (PALC) that drives a liquid crystal as a display unit by plasma discharge. PA
As shown in FIG. 1, the LC 1 includes a first transparent glass substrate 2 that is flat and optically sufficiently transparent, a liquid crystal panel 3 that is disposed in parallel with the first transparent glass substrate 2, and a back panel. And a light 4. PALC1 is
Although not shown, the peripheral portions of the first transparent glass substrate 2 and the liquid crystal panel 3 are supported by frame-shaped spacers. For this reason, in the PALC 1, a predetermined space is formed between the first transparent glass substrate 2 and the liquid crystal panel 3, and the opposing space is formed as a discharge space 5. The discharge space 5 is filled with a discharge gas.

On the first transparent glass substrate 2, a large number of discharge electrodes 6 parallel to each other are arranged at substantially equal intervals on the main surface 2a on the side facing the liquid crystal panel 3.

As shown in FIG. 1, the liquid crystal panel 3 has a second transparent glass substrate 7
, A liquid crystal layer 8, and a dielectric sheet 9. The second transparent glass substrate 7 has a flat shape like the first transparent glass substrate 2, and is made of a non-conductive and optically transparent material.

In the second transparent glass substrate 7, a large number of transparent electrodes 10 (address electrodes) are formed on the surface 7a on the discharge space 5 side. The transparent electrode 10 is formed of a transparent conductive material such as indium tin oxide (ITO) and is optically transparent. Transparent electrode 1
The 0s are arranged in parallel with each other and at substantially equal intervals. The transparent electrodes 10 are arranged in a direction orthogonal to the discharge electrodes 6 arranged on the main surface 2a of the first transparent glass substrate 2, and their intersections correspond to each pixel. . A driving voltage corresponding to a display image is applied to the transparent electrode 10 via a liquid crystal driving unit (not shown).

The liquid crystal layer 8 is made of, for example, a nematic liquid crystal, and is sealed between the second transparent glass substrate 7 and the dielectric sheet 9. The dielectric sheet 9 is made of glass, mica,
It is formed of a non-magnetic thin film made of plastic or the like. The dielectric sheet 9 functions as an insulation barrier between the liquid crystal layer 8 and the discharge space 5, and the liquid crystal material of the liquid crystal layer 8 flows into the discharge space 5 or is sealed in the discharge space 5. The discharge gas acts so that the liquid crystal material of the liquid crystal layer 8 is not contaminated. The dielectric sheet 9 may not be necessary when the liquid crystal layer 8 is formed using a solid or encapsulated electro-optic material instead of a liquid crystal material.

Since the discharge space 5 has a so-called open cell structure in which all of the discharge space 5 is formed as a continuous space,
No partition wall is provided inside. The discharge space 5 is filled with an ionizable discharge gas such as helium, neon, argon, or a mixture thereof. In the discharge space 5, when a driving voltage is applied to a large number of discharge electrodes 6 formed on the first transparent glass substrate 2, the discharge gas sealed in the discharge space 5 is ionized, Plasma discharge occurs.

Although the discharge space 5 is not provided with a partition wall as described above, it is divided into a number of discharge channels 11 by being partitioned by a number of discharge electrodes 6. The discharge channel 11 is a part that performs a switching operation with the above-described transparent electrode 10 based on a driving voltage and drives the liquid crystal layer 8 as a display unit. That is, when a plasma discharge occurs in a state where a signal voltage is applied to the transparent electrode 10, the discharge channel 11 conducts the discharge electrode 6 and the liquid crystal layer 8 by the plasma discharge, that is, a so-called plasma switching operation for the liquid crystal layer 8. I do. The discharge channel 11 corresponds to a scanning line.

The PALC 1 has a schematic configuration as described above, and ionizes the discharge gas in the discharge space 5 to generate a plasma discharge, thereby establishing a conductive state between the transparent electrode 10 and the discharge electrode 6. Then, the liquid crystal layer 8 is driven to display an image.

The scanning circuit and the image display operation in the PALC 1 will be described below. As shown in FIG. 2, the PALC 1 includes a power supply device 12 serving as a power source of a discharge voltage, a discharge voltage control device 13, a plasma discharge unit 14 including a large number of discharge electrodes 6 and discharge channels 11, And a timing pulse generator 16 for providing the control unit 15 with ON / OFF timing pulses. Configuration to the switch unit 15, together with the n switches SW ₁ to SW _n are arranged corresponding to the discharge electrodes 6, each of the switches SW ₁ through SW _n is normally closed contact 15a and the normally open contact 15b Have been.

As shown in FIG. 2, the plasma discharge section 14 includes n discharge electrodes 6 (discharge electrodes K _{1 to} K _n ) arranged between the discharge electrodes 6. n-
One discharge channel 11 (discharge channels P _{1 to} P _1
n-1 ) is formed. Discharge electrodes K ₁ to K _n are connected to the power supply 12 via respective switches SW ₁ to SW _n corresponding switch unit 15. Also,
Discharge electrodes K ₁ to K _n, the timing pulse generator 1
When the timing pulse off is given from 6 switch SW ₁ to SW _n, each of the switches SW
₁ is connected to the normally closed contact 15a of the SW _n, when the timing pulse ON is given, are connected to the normally open contact 15b. The discharge electrodes K ₁ to K _n
Are connected to the normally closed contact 15a,
The potential of the supplied driving voltage is different from that in the case where it is connected to b.

PA having line scanning circuit section as described above
The LC1, discharge electrodes K ₁ and the discharge electrode K ₂ in FIG. 2
Time t ₁ in the discharge channel P ₁ formed between the
The scan for generating the plasma discharge only during the period will be described. PALC1, as shown in FIG. 3, first, the driving voltage supplied to the discharge electrode K ₁ and the discharge electrode K ₂ in order to maintain the same potential, corresponding to each of the discharge electrodes K _1, K ₂ The switches SW ₁ and SW ₂ are connected to normally closed contacts 15a. Thereafter, the PALC1, switch SW ₂ in the discharge channel P ₁ in order to generate the plasma discharge
Is supplied with an ON timing pulse from the timing pulse generator 16.

[0026] PALC1, therefore the discharge electrode K ₂ is connected to the normally open contact 15b of the switch SW _2, discharge electrodes that are connected to the discharge electrode K ₂ and the normally closed contact 15a of the switch SW ₁ potential difference between the K ₁ is generated. Therefore, PALC1 a plasma discharge is generated in the discharge channel P _1.

It should be noted that PALC1 has a discharge channel P ₁
In the same time the plasma discharge is generated, to prevent the plasma discharge is generated in the other discharge channel P ₂ to P _n, all of the discharge electrode K ₃ through K _n of the discharge electrode K ₂ and subsequent discharge electrodes K as ₂ with the same potential, switch S
W ₃ to switch SW from the timing pulse generator 16 timing pulses on given for _n, the discharge electrode K ₃ to K _n is the normally open contact 15b of the respective switches
Connected to.

[0028] PALC1 is after generating a plasma discharge in the discharge channel P ₁ by the time t _1, the normal switch SW ₂ through SW _n corresponding discharge electrode K ₂ through K _n like the discharge electrodes K ₁ by connecting to the closed contact 15a, and terminates the plasma discharge as a same potential for all of the discharge electrodes K ₁ to K _n.

Next, the PALC1, the scanning for plasma discharge only during the time t ₂ in the discharge channel P _m formed between the discharge electrode K _m and the discharge electrode K _{m + 1} will be described. PALC1 the discharge when the plasma discharge occurs in the channel P _m-1, discharge electrodes K ₁ to the discharge electrode K _m-1 between the discharge electrode K _m-1 and the discharge electrode K _m the driving voltage of the connected the same potential to the normally closed contact 15a is applied, the discharge electrode K _m to the discharge electrode K _n is the driving voltage of the connected the same potential to the normally open contact 15b is applied. PALC1 switches SW _m to terminate the plasma discharge in discharge channel P _m-1 .
To connect the discharge electrodes K _m or K _n gives timing pulses off the normally closed contact 15a relative to SW _n. PA
LC1, all of the discharge electrodes K ₁ to K _n normally closed contact 15
a, and is kept at the same potential, the plasma discharge ends. After that, PALC1 sets the discharge channel P
To initiate the plasma discharge in _m, the switch S
The timing pulse generator 16 supplies an OFF timing pulse to W _{m and} an ON timing pulse to SW _{m + 1} .

Therefore, PALC1 is connected to discharge electrode K
_{Since m} is connected to the normally closed contact 15a and the discharge electrode K _{m + 1} is connected to the normally open contact 15b, a potential difference occurs between the two and plasma discharge is started. In addition, PA
The LC1, as simultaneously plasma discharge in other discharge channels and scanning described above is not started, also timing pulses off the switch SW _m for switch SW ₁ to SW _m-1 is, the switch SW m _{+ 2} or timing pulses also on the switch SW m _{+ 1} is given for SW _n.

The PALC 1 always generates a potential difference in one line of the discharge electrode 6 due to the above-described scanning.
Plasma discharge occurs only in the discharge channel 11 formed during this time. In addition, the PALC 1 applies a liquid crystal driving signal in synchronization with this signal simultaneously with the above-described scanning, whereby the plasma switch functions as an active element like a thin film transistor or the like, and drives the liquid crystal layer 8 to display an image. .

[0032]

As described above, according to the image display device of the present invention, the number of discharge electrodes arranged in the discharge space is smaller than that of the conventional image display device. The aperture ratio can be improved. Therefore, in the image display device according to the present invention, the transmission amount of the irradiation light emitted from the backlight increases, and the luminance of the image is improved, so that the image quality can be improved. Further, the image display device according to the present invention has a large aperture ratio of the discharge channel and increases the transmission amount of irradiation light by the backlight when the same luminance as the conventional image display device is to be maintained. The power consumption supplied to the power supply can be reduced, the reliability can be improved, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a P which is an embodiment of an image display device according to the present invention.
It is an important section enlarged longitudinal section of ALC.

FIG. 2 is a circuit diagram showing a PALC scanning circuit.

FIG. 3 is a waveform diagram of a timing pulse supplied to each switch of a PALC switch unit.

FIG. 4 is an enlarged longitudinal sectional view of a main part of a PALC as an example of a conventional image display device.

FIG. 5 is a circuit diagram showing a conventional PALC scanning circuit.

FIG. 6 is a waveform diagram of a timing pulse supplied to each switch of a conventional PALC switch unit.

[Explanation of symbols]

1 plasma-addressed liquid crystal display (PALC), 2
1st transparent glass substrate, 3 liquid crystal panel, 5 discharge space, 6 discharge electrode, 8 liquid crystal layer, 10 transparent electrode (address electrode), 11 discharge channel, 14 plasma discharge unit, 15 control unit

Claims (2)

[Claims] 1. A liquid crystal panel provided with a large number of address electrodes arranged in a row, and is opposed to the liquid crystal panel in parallel with a predetermined opposing interval, and the opposing space portion constitutes a discharge space portion. And a plurality of discharge electrodes arranged on the main surface of the glass substrate in a row orthogonal to the address electrodes, and forming a plurality of parallel discharge channels that divide the discharge space. A control unit including a number of switches for controlling supply and cutoff of a drive voltage to each of the discharge electrodes; and a line scanning circuit for supplying a selection pulse for sequentially opening and closing each switch of the control unit by line-sequential scanning. A predetermined discharge electrode whose potential has been changed by a closing operation of a predetermined switch of the control unit selected by the selection pulse, and a changed potential of the discharge electrode When the potential is the same as the potential of the immediately preceding discharge electrode, a plasma discharge is generated in a discharge channel formed between the discharge electrodes, and the switching with the corresponding address electrode is performed by the plasma discharge. An image display device, wherein the image display is performed by driving a liquid crystal. 2. The line scanning circuit changes the m-th discharge electrode to the same potential as the (m-1) -th discharge electrode, and applies the same to all the m + 1-th and subsequent discharge electrodes. 2. The image display device according to claim 1, wherein supply of a drive voltage to each of the discharge electrodes is controlled so as to change the potential to a potential.