JP3013469B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for driving an electro-optical material layer using plasma to select pixels.

[0002]

2. Description of the Related Art For example, as a means for increasing the resolution and contrast of a liquid crystal display, a method of providing an active element such as a transistor for each display pixel and driving it (a so-called active matrix addressing method) is known. Generally done. However, in this case,
Since it is necessary to provide a large number of semiconductor elements such as thin film transistors, there is a concern about the yield problem, especially when the area is increased, and there is a serious problem that the cost is increased.

In order to solve this problem, Buzak et al. In Japanese Patent Application Laid-Open No. 1-217396 propose a method in which a discharge plasma is used as an active element instead of a semiconductor element such as a MOS transistor or a thin film transistor. Hereinafter, the configuration of an image display device that drives liquid crystal using discharge plasma will be briefly described.

[0004] This image display device, as shown in FIG.
A liquid crystal layer 101 which is an electro-optical material layer;
2 are arranged adjacently via a thin dielectric sheet 103 made of glass or the like. Plasma chamber 10
2 is a plurality of grooves 105 parallel to each other in the glass substrate 104.
And an ionizable gas is sealed therein. Also, each groove 105
Is provided with a pair of electrodes 106 and 107 parallel to each other, and these electrodes 106 and 107 are connected to the plasma chamber 10.
It functions as an anode and a cathode for ionizing the gas in 2 to generate discharge plasma. On the other hand, the liquid crystal layer 101 is composed of the dielectric sheet 103 and the transparent substrate 108.
And the liquid crystal layer 1 of the transparent substrate 108.
A transparent electrode 109 is formed on the surface on the 01 side.
This transparent electrode 109 is orthogonal to the plasma chamber 102 defined by the groove 105, and
The intersection of 09 and the plasma chamber 102 corresponds to each pixel.

In the above-described image display apparatus, the plasma chamber 102 in which plasma discharge is performed is sequentially switched and scanned, and a signal voltage is applied to the transparent electrode 109 on the liquid crystal layer 101 side in synchronization with the scanning. Is held in each pixel, and the liquid crystal layer 101 is driven. Therefore, each groove 105, that is, each plasma chamber 102 corresponds to one scanning line, and the discharge region is divided for each scanning unit.

[0006]

By the way, it is considered that an image display device using discharge plasma can be easily made larger in area than a device using a semiconductor element as described above. Various problems remain. For example, the groove 10 for forming the plasma chamber 102
Forming 5 on a glass substrate 104, which is a transparent dielectric substrate, involves considerable difficulty in manufacturing, and particularly, it is extremely difficult to form grooves 105 at high density.

Further, the plasma chamber 102 is formed by the groove 105.
When each of the plasma chambers 102
Liquid crystal layer 10 in the ridge portion of glass substrate 104 separating
1 is an invalid portion that is not driven. Further, each groove 105
In the portion where the wall surface is inclined or curved, the direction and polarization state of the transmitted light are disturbed, which hinders appropriate brightness control and the like. That is, the presence of the groove 105 may have an undesirably large effect on the contrast and the transmittance when an image is displayed.

Accordingly, the present invention has been proposed to solve the problems of the prior art, and an object of the present invention is to provide an image display device which is easy to manufacture and has excellent image quality.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a vehicle, comprising:
A first substrate having an electrode; and a second substrate having a plurality of second electrodes on one main surface substantially orthogonal to the first electrode and substantially parallel to each other. Are arranged substantially in parallel with each other so that the first electrode and the second electrode face each other, and an electro-optic material layer is interposed so as to be in contact with the first electrode of the first substrate, and the electro-optic material is An ionizable gas is sealed between the layer and the second substrate to form a discharge region, and the gas is selectively ionized by a discharge between adjacent second electrodes. The electro-optic material layer at the intersection with the first electrode is driven, and a discharge region for a plurality of scanning units is a continuous space.

[0010]

In the image display apparatus according to the present invention, since the discharge regions for a plurality of scanning units are continuous spaces, the number of grooves for forming the plasma chamber is greatly reduced, and the manufacturing is easy. It will be. In particular, if a so-called open cell structure is used as a continuous space for the discharge regions for all scanning units, the formation of a groove is not required at all, and its manufacture is extremely easy. In addition, if the number of grooves is reduced, ineffective portions due to the convex portions existing between the grooves and disturbance of transmitted light due to the wall surfaces of the grooves are necessarily reduced, and transmittance and contrast are secured.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below in detail with reference to the drawings. The image display device of the present embodiment is a flat panel display having a so-called open cell structure in which all discharge regions are formed as continuous spaces. Therefore, there is no partition separating the discharge region. Hereinafter, the configuration of the image display device according to the present embodiment will be described.
As shown in FIG. 2, a liquid crystal layer 3 which is an electro-optical material layer is interposed between a flat and optically sufficiently transparent first substrate 1 and a flat and transparent second substrate 2 as well. At the same time, the space between the liquid crystal layer 3 and the second substrate 2 serves as a discharge region 4. Here, these substrates 1 and 2 are formed of a non-conductive and optically transparent material. However, this is in consideration of a transmissive display device. Suffices that one of the substrates is transparent.

On the first substrate 1, a band-shaped electrode 5 is formed on one main surface 1a, and a liquid crystal layer 3 made of a nematic liquid crystal or the like is arranged in contact with the electrode 5. The liquid crystal layer 3 is sandwiched between the first substrate 1 and a thin dielectric film 6 made of glass, mica, plastic, or the like. , A so-called liquid crystal cell is formed. The dielectric film 6 functions as an insulation barrier between the liquid crystal layer 3 and the discharge region 4.
Otherwise, the liquid crystal material may flow into the discharge region 4 or the gas in the discharge region 4 may contaminate the liquid crystal material.
However, when a solid or encapsulated electro-optic material or the like is used instead of the liquid crystal material, it may not be necessary. Further, since the dielectric film 6 is formed of a dielectric material, the dielectric film 6 itself also functions as a capacitor,
Therefore, in order to sufficiently secure the electrical coupling between the discharge region 4 and the liquid crystal layer 3 and to suppress the two-dimensional diffusion of the electric charge, the thinner the better, the better.

On the other hand, a discharge electrode group 7 is also formed on the second substrate 2 as a strip electrode, and the periphery thereof is supported by a frame-shaped spacer 8, so that the discharge electrode group 7 is arranged at a predetermined distance from the dielectric film 6. The space between the second substrate 2 and the dielectric film 6 is a discharge region 4 for generating discharge plasma. Therefore, the discharge region 4 is a continuous space over the entire screen. The discharge region 4 is filled with an ionizable gas. As the ionizable gas, helium, neon, argon, or a mixed gas thereof is used.

The above is the schematic configuration of the image display device of the present embodiment. The electrodes for driving the liquid crystal layer 3 are formed on each of the substrates 1 and 2. Therefore, these electrode configurations will be described next.

First, on the main surface 1a of the first substrate 1 facing the second substrate 2, a plurality of strip-shaped electrodes 5 having a predetermined width are formed. These electrodes 5 are formed of a transparent conductive material such as indium tin oxide (ITO) and are optically transparent. Also,
The electrodes 5 are arranged in parallel with each other, for example, arranged perpendicular to the screen. On the other hand, the discharge electrode group 7 is also formed on the main surface 2a of the second substrate 2 facing the first substrate. These discharge electrode groups 7 are also parallel linear electrodes, but the arrangement direction is a direction orthogonal to the electrodes 5 formed on the first substrate 1. That is, these discharge electrode groups 7 are arranged horizontally on the screen. The discharge electrode group 7 includes anode electrodes A ₁ , A ₂ , A _3.
·· A _n-1, A _n and the cathode electrode _{K 1, K 2, K 3} ··
· Consists K _n-1, K n, the discharge electrodes and these paired is constructed.

FIG. 3 schematically shows the arrangement of the electrodes 5 formed on the first substrate 1 and the discharge electrode groups 7 formed on the second substrate. Here, a first signal applying means composed of a data driver circuit 9 and an output amplifier 10 is connected to the electrode 5 of the first substrate 1, and an analog voltage output from each output amplifier 10 is applied to a liquid crystal drive signal. Supplied as In contrast, among the second discharge electrode groups 7 on the substrate 2, each cathode _{K 1, K 2, K 3} ··· K n-1, K n is
Second signal applying means including a data strobe circuit 11 and an output amplifier 12 is connected, and a pulse voltage output from each output amplifier 12 is supplied as a data strobe signal. Further, each of the anode electrodes A ₁ , A ₂ ,
The _{A 3 ··· A n-1,} A n, common reference voltage (ground voltage) is applied. Therefore, the connection structure of the discharge electrode group 7 formed on the second substrate 2 is as shown in FIG. In order to form an image over the entire display surface, a scanning control circuit 13 is provided in connection with the data driver circuit 9 and the data strobe circuit 11.
The scanning control circuit 13 adjusts the functions of the data driver circuit 9 and the data strobe circuit 11, and sequentially addresses all the pixel columns of the liquid crystal layer 3 from row to row.

In the image display device having the above configuration, the liquid crystal layer 3 functions as a sampling capacitor for an analog voltage applied to the electrode 5 formed on the first substrate 1, and discharge generated in the discharge region 4. An image is displayed by the plasma functioning as a sampling switch. FIG. 5 shows a model for explaining this image display operation. In FIG. 5, the liquid crystal layer 3 corresponding to each pixel can be regarded as a capacitor model 14. That is, the capacitor model 14 represents a capacitive liquid crystal cell formed at a portion where the electrode 5 and the region where the gas is ionized overlap.

Now, it is assumed that an analog voltage is applied to each electrode 5 from the data driver circuit 9. Here, the second
When the data strobe signal to the cathode electrodes K ₁ of the substrate 2 (pulse voltage) is not been applied, i.e. when to be in an off state, does not occur discharge of the anode electrode A ₁ and the cathode electrode K _1, the neighborhood Is in a non-ionized state. Therefore, the plasma switch S ₁ (the electrical connection between the electrode 5 and the anode electrode A ₁ ) is also turned off, so that no matter what analog voltage is applied to the electrode 5, the potential difference applied to each capacitor model 14 is reduced. No change.

On the other hand, when the data strobe signal is applied to the cathode electrode K ₂ of the second substrate 2, that is, when the data strobe signal is in the ON state, the gas is discharged by the discharge between the anode electrode A ₂ and the cathode electrode K _2. It is ionized, and an ionized region (discharge plasma) is generated in a band along these electrodes A ₂ and K ₂ . Then, the electrode 5 and the anode electrode A ₂ are electrically connected by a so-called plasma switching operation, which is equivalent to a state in which the plasma switch S ₂ is turned on in terms of a circuit. As a result, the capacitor model 14 of the column where the cathode electrode K ₂ is strobed, an analog voltage supplied to the electrode 5 is stored. After the strobe to the cathode electrode K ₂ is completed discharge plasma is lost even during (during field period of at least the image) until the next strobe is carried out each analog voltage to the capacitor model 14 Store And remains unaffected by subsequent changes in the analog voltage applied to the electrode 5.

Therefore, the cathode electrodes K ₁ , K ₂ , K
₃ ... Kn _-1 and _Kn are sequentially addressed and a data strobe signal is applied, and at the same time, a liquid crystal drive signal is applied as an analog voltage to each electrode 5 in synchronization with the data strobe signal. Like a semiconductor element such as a thin film transistor, it functions as an active element, and the liquid crystal layer 3 is driven similarly to the active matrix addressing method. In this case, a pair of anode electrodes A ₁ , A ₂ , A _3.
A _n-1, A _n and the cathode electrode _{K 1, K 2, K 3} ··· K
strip ionization region generated between _n-1, K _n corresponds to each scanning line, each of these ionization region is that the scanning unit.

In the image display device of the above-described embodiment, since the discharge area 4 is a continuous space over the entire screen, there is a concern that the resolution may be degraded due to diffusion of charged particles generated by the discharge. However, this is solved as follows. First, as is well known, as the gas pressure of the gas sealed in the discharge region 4 increases, the mean free path of the charged particles decreases and the localization tends to occur. Therefore, by setting this gas pressure to a certain high level, it is possible to control the discharge plasma to an appropriate spread.

However, if the gas pressure is increased, the firing voltage may be increased. According to Paschen's law, the distance between the discharge electrodes, that is, each of the anode electrodes A ₁ , A ₂ , A _3.
A _n-1, A _n and the cathode electrode _{K 1, K 2, K 3} ··· K
The distance d between the _n-1, K _n may be adjusted by decreasing in inverse proportion to the gas pressure. The optimum values of the gas pressure and the electrode spacing d vary depending on the type of gas used and the like. For example, when a Ne—Ar mixed gas is used and the electrode spacing d is 0.1 mm, discharge can be performed at 1 atm. there were.

Also, the effective spread of the discharge plasma can be controlled to some extent by reducing the gap interval W of the discharge region 4 to some extent. Experimentally, the gap interval W is defined as W ≦ p with respect to the discharge electrode pitch p.
Within this range, sufficient localization is possible.

As described above, the deterioration of the resolution due to the diffusion of the charged particles can be eliminated. However, even if the discharge plasma is spread to some extent and these are overlapped with each other, the blur is substantially reduced. Does not cause the For example, when the discharge plasmas corresponding to the respective scan units overlap each other, in the middle part of the adjacent discharge electrode pair (a pair of anode and cathode corresponding to each scan unit), two discharge electrodes cause a discharge. Although the signal is written once, the signal written second time is actually held for one field or one frame. That is,
For example, assuming non-interlaced scanning with 400 scanning lines, the first written signal is held only for one line, whereas the second written signal is For 399 lines. Therefore, in this case, the crosstalk amount due to the first signal writing is 1/400 (= 0.25)
%), Which is completely negligible.

On the other hand, as an advantage of adopting the structure of the present embodiment, first, it is pointed out that the manufacture becomes very easy. That is, in the image display device of the present embodiment, the discharge region 4 is a continuous space, and there is no need to form a groove in the second substrate 2. Therefore, groove processing involving many difficulties is not required, and productivity is greatly improved. One of the great advantages is that the ineffective portion and the disturbance of the transmitted light, which have become problems in the groove type structure, can be eliminated, whereby characteristics such as contrast and transmittance can be remarkably improved.

Further, another advantage of the structure of this embodiment is that charged particles generated in one discharge electrode pair are automatically supplied to the vicinity of the discharge electrode pair of the next scanning line by diffusion, thereby stably. The discharge is scanned. This is due to the so-called priming effect in which the supply of the charged particles reduces the statistical delay time from the application of the voltage to the start of the discharge.

The embodiment of the present invention has been described above. However, the present invention is not limited to this embodiment. For example, in the embodiment, the discharge region is a space continuous over the entire screen, but a configuration in which a partition is provided for each of a plurality of discharge electrode pairs may be employed. Also in this case, the number of grooves can be greatly reduced as compared with the case where each pair of discharge electrodes is formed in the groove one by one, and an effect on manufacturing and characteristics can be expected.

[0028]

As is apparent from the above description, in the image display device of the present invention, grooves and partitions for separating the ionized region (plasma chamber) for each scanning unit can be greatly reduced. , Can be significantly easier to manufacture. In particular, if the plasma chamber is formed as one continuous space over the entire screen, it is not necessary to form the grooves and the partition walls, and the manufacture thereof is extremely easy. In addition, it is possible to reduce ineffective portions and the like that are inevitably generated when grooves or partition walls are present, thereby increasing transmittance and contrast and improving image quality. Further, in the image display device of the present invention, a priming effect can be naturally obtained, and stable discharge can be performed.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a main part of an embodiment to which the present invention is applied, which is partially cut away.

FIG. 2 is an enlarged sectional view of a main part of an embodiment to which the present invention is applied.

FIG. 3 is a schematic diagram showing an electrode configuration for driving a liquid crystal layer.

FIG. 4 is a schematic diagram showing the arrangement and connection state of discharge electrodes.

FIG. 5 is an equivalent circuit diagram for explaining an image display operation in one embodiment to which the present invention is applied.

FIG. 6 is an enlarged perspective view of a main part of an example of a conventional image display device, partially cut away.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate 2 ... 2nd board | substrate 3 ... Liquid crystal layer (electro-optic material layer) 4 ... Discharge area 5 ... Electrode 7 ... Discharge electrode group

Claims (1)

(57) [Claims] 1. A first substrate having a plurality of first electrodes substantially parallel to each other on one main surface, and a plurality of second electrodes substantially orthogonal to the first electrodes and substantially parallel to each other on one main surface. The second with
The first substrate and the second substrate are the first substrate.
An electrode and a second electrode are arranged substantially parallel to each other so as to face each other. An electro-optic material layer is interposed between the first and second electrodes so as to be in contact with the first electrode of the first substrate. An ionizable gas is sealed between the substrates to form a discharge region, and the gas is selectively ionized by a discharge between adjacent second electrodes, and the selective ionization region is used as a scan unit to communicate with the first electrode. An image display device configured to drive an electro-optic material layer at an intersection and to form a discharge space for a plurality of scanning units as a continuous space.