JP3451730B2 - Plasma address display - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma address display device in which an electro-optical display cell having an electro-optical material layer and a plasma cell are laminated via a dielectric sheet.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a conventional plasma addressed display device. Reference numeral 100 denotes a plasma addressed display element that utilizes the twisted nematic (TN) effect of liquid crystal. A polarizing plate 10 is provided on the lower surface side of the display element 100.
1, and a polarizing plate 102 is arranged on the upper surface side. The polarization planes of the polarizing plates 101 and 102 are set to be orthogonal to each other, and the light emitted from the display element 100 is transmitted through the polarizing plate 102 when no voltage is applied to the liquid crystal (normally white mode). . Reference numeral 103 denotes a backlight unit for irradiating the polarizing plate 101 side.

6 and 7 show an example of the structure of the plasma addressed liquid crystal display device 100. In the figure, the display element 100 has a flat panel structure in which a liquid crystal display cell 1, a plasma cell 2, and a dielectric sheet 3 interposed therebetween are laminated. The dielectric sheet 3 is made of thin glass plate or the like. This dielectric sheet 3 is a liquid crystal display cell 1.
It is necessary to make the thickness as thin as possible in order to drive, and it is formed to have a plate thickness of, for example, about 50 μm.

The liquid crystal display cell 1 is composed of a transparent substrate 4. On the inner main surface of the transparent substrate 4, a plurality of data electrodes 5 made of a transparent conductive material and extending in the row direction are formed in parallel in the column direction with a predetermined space therebetween. The transparent substrate 4 is bonded to the dielectric sheet 3 with a spacer 6 holding a predetermined gap. A liquid crystal layer 7 is formed by filling the gap between the transparent substrate 4 and the dielectric sheet 3 with liquid crystal as an electro-optical material. Here, the size of the gap between the transparent substrate 4 and the dielectric sheet 3 is, for example, 4 to 10 μm, and is kept uniform over the entire display surface.

On the other hand, the plasma cell 2 is constructed using a glass substrate 8. On the inner main surface of the glass substrate 8, a plurality of grooves 9 extending in the column direction are formed in parallel in the row direction. Each groove 9 is sealed by the dielectric sheet 3, and individually formed discharge channels (plasma chambers) 10 are formed. In this case, the discharge channel 10 is formed in a substantially bow-shaped cross section, and the chord portion 10a is formed by the sheet surface of the dielectric sheet 3,
The arc portion 10b is formed by the surface of the groove 9. An ionizable gas is enclosed in the sealed discharge channel 10. As the gas to be sealed, for example, helium, neon, argon, or a mixed gas thereof is used.

The ridges 11 separating the adjacent grooves 9 serve not only as partition walls for partitioning the individual discharge channels 10 but also as gap spacers for the respective discharge channels 10. An anode electrode 12A and a cathode electrode 12K, which form a plasma electrode and are parallel to each other, are formed along the groove 9 at the bottom of each groove 9.

The discharge channel 10 is formed so as to be orthogonal to the data electrode 5. Although not described above, each data electrode 5 serves as a column driving unit, each discharge channel 12 serves as a row driving unit, and a pixel 13 is defined at the intersection of the two as shown in FIG.

In the above structure, the anode electrode 12A and the cathode electrode 12 corresponding to the predetermined discharge channel 10 are formed.
When a predetermined voltage is applied between K and K, the gas in the portion of the discharge channel 10 is selectively ionized to generate plasma discharge, and the inside thereof is maintained at substantially the anode potential.
When a data voltage is applied to the data electrode 5 in this state, the data voltage is written to the liquid crystal layers 7 of the plurality of pixels 13 arranged in the column direction corresponding to the discharge channel 10 via the dielectric sheet 3. When the plasma discharge ends, the discharge channel 10 becomes a floating potential, and the liquid crystal layer 7 of each pixel 13
The data voltage written in is held until the next writing period (for example, one frame later). In this case, the discharge channel 10 functions as a sampling switch, and the liquid crystal layer 7 of each pixel 13 functions as a sampling capacitor.

Since the liquid crystal is operated by the data voltage written in the liquid crystal layer 7 of each pixel 13, display is performed in pixel units. Therefore, as described above, the liquid crystal layer 7 of the plurality of pixels 13 arranged in the column direction by generating the plasma discharge.
A two-dimensional image can be displayed by sequentially scanning the discharge channel 10 for writing the data voltage in the row direction.

When the TN effect is used in the plasma addressed display element 100 as described above, the narrow viewing angle of the liquid crystal display cell 1 poses a serious problem. This is because the angle of light passing through the liquid crystal layer 7 changes depending on the viewing angle, and the electro-optical threshold value of the liquid crystal (applied voltage value at which the transmittance becomes 50%, for example) changes.
That is, when the TN mode is used, the orientation of the liquid crystal forming the liquid crystal layer 7 on the side of the dielectric sheet 3 is an arrow Qa in FIG. 9, and the orientation of the liquid crystal layer 7 on the side of the transparent electrode 4 is an arrow Qb in the figure.
, The vertical viewing angle is −30.
Applied voltage V and transmittance T at °, 0 ° (front) and + 30 °
The relationship (VT characteristic) is as shown by the alternate long and short dash line a, solid line b, and broken line c in FIG. Therefore, for example, when the applied voltage V is the predetermined value Va, there is a large difference between the transmittances T at the vertical viewing angles of −30 °, 0 ° (front), and + 30 °, which narrows the viewing angle.

Even when an electro-optical display cell other than the liquid crystal display cell 1 is used, when the electro-optical material layer has a deviation of the electro-optical threshold value depending on the viewing angle, the above-mentioned liquid crystal display cell 1 is used. As in the case of use, the narrow viewing angle poses a problem.

Therefore, in order to expand the viewing angle, FIG.
As shown in FIG. 5, the backlight unit 103 emits light close to parallel light, and the light diffusion plate 10 is provided on the polarizing plate 102 side.
It is possible to arrange four. The light diffusion plate 104 is shown in FIG.
As shown in FIG. 2, it is composed of, for example, microlenses (the polarizing plate 102 is omitted in FIG. 12). In this case, the light (shown by broken lines) that has passed through each pixel portion of the liquid crystal display cell 1 of the plasma addressed display element 100 almost vertically is diffused by the light diffusion plate 104 and emitted. As a result, the relationship between the applied voltage V and the transmittance T at each viewing angle (V-
(T characteristic) can be made closer, and the viewing angle can be expanded.

[0013]

According to the arrangement of the light diffusing plate 104 on the side of the polarizing plate 102 in order to widen the viewing angle as described above, the microlenses forming the light diffusing plate 104 are formed by plasma. It is necessary to accurately align each discharge channel 10 of the plasma cell 2 that constitutes the address display element 100, and this alignment is difficult. Further, the transparent substrate 4 on the liquid crystal display cell 1 side of the display element 100 is relatively thick, and the liquid crystal layer 7
Since the distance between the light diffusion plate 104 and the light diffusion plate 104 is wide, when the light from the backlight unit 103 is not close to parallel light, the light beams that have passed through the respective pixel portions of the liquid crystal display cell 1 are respectively reflected by the light diffusion plate 1.
There is a problem in that the resolution is deteriorated because the light enters in a wide range of 04.

Therefore, according to the present invention, it is not necessary to perform highly accurate alignment, and even if the light from the backlight unit is not close to parallel light, the resolution is not deteriorated and the viewing angle can be expanded. Is provided.

[0015]

According to another aspect of the present invention, there is provided a plasma addressed display device having an electro-optical material layer and a plurality of data electrodes arranged in parallel on one surface of the electro-optical material layer. In a plasma address display device in which a plasma cell in which a plurality of discharge channels are provided in parallel to each other on the other surface of the electro-optical display cell at right angles to the data electrode is laminated with a dielectric sheet, A backlight portion is disposed in the discharge channel, and the discharge channel is formed so that its cross section has a substantially arcuate shape and its chord portion is located on the backlight portion side.

A plasma addressed display device according to a second aspect of the present invention is the plasma addressed display device according to the first aspect of the invention, wherein the light emitted from the backlight portion to the electro-optical display cell is substantially parallel light.

[0017]

According to the present invention, the light from the backlight portion passes through each pixel portion of the electro-optical display cell and is incident on each discharge channel of the plasma cell from the chord portion. The light that has passed through the electro-optical material layer almost vertically and is incident on the curved surface of the arc portion of the discharge channel is emitted to the outside by the concave lens effect. As a result, the applied voltage-transmittance characteristic (VT characteristic) at each viewing angle is close to each other, so that the viewing angle can be expanded.

Further, since a light diffusing plate composed of a microlens or the like is not provided for enlarging the viewing angle, highly accurate alignment is not necessary. In addition, since the light is diffused by the concave lens effect of each discharge channel, the distance between the electro-optical material layer and the light diffusing portion of the electro-optical display cell is closer to that of the case where the light diffusing plate is provided separately, and the backlight portion Even if the light from the pixel is not close to parallel light, the light that has passed through each pixel portion of the electro-optical display cell does not enter the wide range of the light diffusion portion, for example, a plurality of discharge channels, and prevents deterioration of resolution. Is possible.

According to the second aspect of the present invention, the light emitted from the backlight portion to the electro-optical display cell is made to be substantially parallel light, and the light incident on the curved surface area of the arc portion of the discharge channel has a concave lens effect. The light emitted from the back light portion is almost perpendicular to the electro-optical material layer at the time of passing through the electro-optical material layer, so that the VT characteristic at each viewing angle can be made extremely close, and the efficiency can be improved. It is possible to expand the viewing angle.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, FIGS.
The same reference numerals are given to the portions corresponding to, and the detailed description thereof will be omitted.

In this example, the data electrode 5 is formed corresponding to the data electrode 5 formed on the inner main surface of the transparent substrate 4.
And the liquid crystal layer 7, the red (R), green (G), and blue (B) color filters 21 are sequentially formed in the horizontal direction. in this case,
The color filter 21 is formed only in the effective region in the vertical direction except for the light-shielding portion 27 which is hatched. A black black mask (not shown) is formed between the data electrodes 5 in the horizontal direction.

Alignment films 22 and 23 are provided on the transparent substrate 4 side and the dielectric sheet 3 side of the liquid crystal layer 7, respectively.
Are arranged, and the respective alignment directions are set so that the liquid crystal operates in, for example, a TN (twist nematic) mode.

Further, in this example, the polarizing plate 24 is arranged outside the transparent substrate 4. The polarization plane direction of the polarizing plate 24 is set to coincide with the alignment direction of the alignment film 22 of the liquid crystal film 7 on the transparent substrate 4 side. On the other hand, the polarizing plate 25 is arranged outside the glass substrate 8. The polarization plane direction of the polarizing plate 25 is the alignment film 23 on the dielectric sheet 3 side of the liquid crystal film 7.
It is set so as to coincide with the orientation direction by. And
Reference numeral 26 denotes a backlight unit for irradiating the polarizing plate 24 side.

This example is constructed as described above, and the operation of the plasma addressed display element 100 itself is the same as the example of FIGS. In this example, some of the light from the backlight unit 26 partially blocks the light.
After being shielded from light by 7, it passes through each pixel portion of the liquid crystal display cell 1 and enters each discharge channel 10 of the plasma cell 2.
As described above, each discharge channel 10 is formed in a bow shape in cross section, the chord portion 10a is formed by the surface of the dielectric sheet 3, and the arc portion 10b is formed by the surface of the groove 9 of the glass substrate 8. The light from the backlight unit 26 is discharged through the discharge channel 10.
Is incident from the string portion 10a.

Here, when the light from the backlight unit 26 is not parallel light, the arc portion 10b of the discharge channel 10 becomes flatter as the angle of the emitted light from the plasma cell 2 deviates from the vertical, that is, as the positive and negative viewing angles increase. Area 10b ₁
The proportion of light incident on the
The ratio of the light incident on the curved surface region 10b ₂ is increased.
Since the curved surface region 10b ₂ exhibits a concave lens effect,
As indicated by a broken line, light passing through the liquid crystal layer 7 at an angle close to vertical is emitted to the outside by the concave lens effect. As a result, even when the user looks from above and below, the light that has passed through the liquid crystal layer 7 at an angle close to vertical can be observed, and the VT characteristics at each viewing angle become closer, so that the viewing angle can be expanded.

For example, a vertical viewing angle of -30 °, 0 °
The VT characteristics at (front) and + 30 ° are as shown by the alternate long and short dash line a, the solid line b, and the broken line c in FIG. 3, respectively, and in the vertical direction when the applied voltage V has a predetermined value Va as compared with the conventional example. The difference between the transmittances T at the viewing angles of −30 °, 0 ° (front), and + 30 ° becomes smaller, and the viewing angle consequently widens (see FIG. 10 for the conventional VT characteristic).

Further, in the present embodiment, since a light diffusing plate composed of a microlens or the like is not provided in order to enlarge the viewing angle, it is not necessary to perform highly accurate alignment. Further, the light is diffused by the concave lens effect of each discharge channel 10, and the distance between the liquid crystal layer 7 and the light diffusing portion is closer to that in the case where the light diffusing plate is provided, and the light from the backlight portion 26 is parallel light. Even if it is not close to, the light passing through each pixel portion of the liquid crystal display cell 1 does not enter a wide range of the light diffusion portion, for example, the plurality of discharge channels 10, and deterioration of resolution can be prevented. Further, since no light diffusing plate is provided, there is an advantage that the cost can be reduced.

Although FIG. 4 shows the optical path when the light from the backlight unit 26 is substantially parallel light, the light incident on the curved surface region 10b ₂ of the arc portion 10b is outward due to the concave lens effect. Is emitted. In this case, when the light from the backlight unit 26 passes through the liquid crystal layer 7,
To V- at each viewing angle,
The T characteristics become extremely close, so that the viewing angle can be effectively expanded.

Although the plasma addressed display element 100 has the liquid crystal display cell 1 in the above-mentioned embodiment, the plasma addressed display having the electro optical display cell having the electro optical material layer other than the liquid crystal is shown. Even when the element is used, when the electro-optical material layer has a deviation of the electro-optical threshold value depending on the viewing angle, the viewing angle can be expanded by applying the present invention.

[0030]

According to the present invention, the light from the backlight portion passes through each pixel portion of the electro-optical display cell and is incident on each discharge channel of the plasma cell from the chord portion, so that the electro-optical material layer is formed. The light that has passed through the curved portion of the arc portion of the discharge channel substantially vertically and is emitted to the outside due to the concave lens effect, so that the VT characteristic becomes closer at each viewing angle, and the viewing angle can be expanded. .

Further, since a light diffusing plate composed of a microlens or the like is not provided for enlarging the viewing angle, it is possible to eliminate the need for highly accurate alignment. Also, it is diffused by the concave lens effect of each discharge channel,
Compared to the case where the light diffusing plate is provided, the distance between the electro-optical material layer of the electro-optical display cell and the light diffusing portion is close, and even if the light from the backlight portion is not close to parallel light, each of the electro-optical display cell Light passing through the pixel portion does not enter a wide range of the light diffusion portion, for example, a plurality of discharge channels, and deterioration of resolution can be prevented. Further, since the light diffusion plate is not separately arranged, the cost can be reduced.

According to the second aspect of the present invention, the light emitted from the backlight portion to the electro-optical display cell is made to be substantially parallel light, and the light incident on the curved surface region of the arc portion of the discharge channel is a concave lens. Because of the effect, the light is emitted to the outside, and the light from the backlight portion is almost perpendicular to the electro-optical material layer when passing through the electro-optical material layer.
The VT characteristic at each viewing angle becomes extremely close, and the viewing angle can be efficiently expanded.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a plasma addressed display device according to the present invention.

FIG. 2 is a diagram showing an optical path of light from a backlight unit (when it is not parallel light).

FIG. 3 is a diagram showing the relationship between applied voltage and transmittance.

FIG. 4 is a diagram showing an optical path of light from a backlight unit (when the light is substantially parallel light).

FIG. 5 is a diagram showing a configuration example of a plasma address display device.

FIG. 6 is a perspective view showing a configuration example of a plasma addressed display element.

FIG. 7 is a cross-sectional view showing a configuration example of a plasma addressed display element.

FIG. 8 is a diagram showing an arrangement of data electrodes, plasma electrodes, and discharge channels.

FIG. 9 is a diagram showing an alignment direction of liquid crystal.

FIG. 10 is a diagram showing the relationship between applied voltage and transmittance.

FIG. 11 is a diagram showing a configuration example of a plasma address display device.

FIG. 12 is a diagram showing a specific example of a light diffusion plate.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid crystal display cell 2 Plasma cell 3 Dielectric sheet 4 Transparent substrate 5 Data electrode 7 Liquid crystal layer 8 Glass substrate 10 Discharge channel 10a Chord portion 10b Arc portion 10b ₂ Curved region 12A Anode electrode 12K Cathode electrode 22,23 Alignment film 24,25 Polarizing plate 26 Backlight part 27 Light-shielding part

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Claims (2)

(57) [Claims] 1. An electro-optical display layer having an electro-optical material layer and having a plurality of data electrodes arranged in parallel on one surface of the electro-optical material layer and perpendicular to the data electrodes on the other surface of the electro-optical display cell. In a plasma addressed display device in which plasma cells having a plurality of discharge channels provided in parallel are laminated via a dielectric sheet, a backlight unit is disposed on the electro-optical display cell side, and the discharge channels have a cross section. A plasma address display device, which is substantially bow-shaped and is formed such that its chord portion is located on the backlight portion side. 2. The plasma addressed display device according to claim 1, wherein the light emitted from the backlight unit to the electro-optical display cell is substantially parallel light.