JP3104706B1 - Image display device - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To eliminate degradation of dynamic resolution when performing an interlace operation without changing a drive circuit. SOLUTION: In an image display device for displaying an image by sequentially scanning a linear discharge plasma region along a scanning line, a plurality of discharge electrodes are arranged in a discharge space at substantially equal intervals at an arrangement pitch of the scanning lines. Then, scanning is sequentially performed with a combination of different discharge electrodes shifted by one scanning line for each field, and interlace driving is performed. As a result, the spread (width) of each discharge plasma region is twice the scanning unit.
When interlaced scanning is performed with discharge plasma having such a spread, all pixels on the screen are completely rewritten in one field, and the previous image does not remain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] 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,
In particular, when the area is increased, there is a concern about the yield problem, and there is a big problem that the cost is inevitably 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 for driving liquid crystal using discharge plasma will be briefly described.

This image display device is called a plasma-addressed liquid crystal display device (PALC).
0, a liquid crystal layer 101 which is an electro-optical material layer
And a plasma chamber 102 are disposed adjacent to each other via a thin dielectric sheet 103 made of glass or the like.

The plasma chamber 102 is formed by forming a plurality of grooves 105 parallel to each other on a glass substrate 104, in which an ionizable gas is sealed. Each groove 105 is provided with a pair of electrodes 106 and 107 parallel to each other.
6, 107 function as an anode and a cathode for ionizing the gas in the plasma chamber 102 to generate discharge plasma.

On the other hand, the liquid crystal layer 101 is sandwiched between the dielectric sheet 103 and the transparent substrate 108.
A transparent electrode 109 is formed on the surface of the transparent substrate 108 on the liquid crystal layer 101 side. The transparent electrode 109 is orthogonal to the plasma chamber 102 defined by the groove 105, and the intersection between the transparent electrode 109 and the plasma chamber 102 corresponds to each pixel.

In the above-described image display device, 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.

[0011]

By the way, if the above-mentioned image display device is driven by an interlace method,
The following inconveniences have occurred.

That is, in the conventional PALC, simply interlaced driving causes each pixel to be scanned only in every other field (for example, 33 ms in the NTSC system). At this time, if a moving image is displayed, an image one field before remains in the screen every other line, and therefore unpleasant blur occurs particularly at the end of the image, and the image quality is significantly impaired. In addition, flicker of two-frame synchronization may occur due to the polarity inversion of the liquid crystal.

As means for solving this problem, as in the case of a TFT type liquid crystal display device, for example, interlaced scanning is converted into sequential scanning by image processing, or two scanning lines in which a combination of one line signal is changed for each field. It is conceivable to adopt a method such as inputting the information to a user.

However, in any case, a line memory is required, the writing time for each line is reduced by half, and the load on the drive circuit is large, and the cost is increased.

The present invention has been proposed in order to solve the problems of the prior art, and can solve the deterioration of the dynamic resolution when performing the interlace operation without changing the drive circuit. It is an object to provide an image display device.

[0016]

To achieve the above object, the present invention provides an image display apparatus for displaying an image by sequentially scanning a linear discharge plasma region along a scanning line. In addition, a plurality of discharge electrodes are arranged at substantially equal intervals at an arrangement pitch of scanning lines, and scanning is sequentially performed by a combination of different discharge electrodes shifted by one scanning line for each field, and interlace driving is performed. Things.

[0017]

In the image display apparatus according to the present invention, a plurality of discharge electrodes are arranged in the discharge space at substantially equal intervals at an arrangement pitch of the scanning lines, and a combination of different discharge electrodes is shifted by one scanning line for each field. Sequential scanning is performed. Thus, for example, in the case of 2: 1 interlace scanning, the spread (width) of each discharge plasma region is set to twice the scanning unit.

When interlaced scanning is performed with discharge plasma having such a spread, all pixels on the screen are completely rewritten in one field, and the previous image does not remain.

Therefore, the problem of the deterioration of the dynamic resolution (the occurrence of blur) due to the interlacing is solved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image display device to which the present invention is applied will be described in detail with reference to the drawings.

The image display device of this 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.

The structure of the image display device according to the present embodiment will be described below. The image display device according to the present embodiment comprises a flat, optically sufficiently transparent first substrate as shown in FIGS. 1
And a liquid crystal layer 3, which is an electro-optical material layer, between the flat and transparent second substrate 2 and a space between the liquid crystal layer 3 and the second substrate 2 in a discharge region. 4 is obtained.

The substrates 1 and 2 are formed of a non-conductive and optically transparent material in this case, taking into consideration a transmission type display device, and a direct view type or reflection type display device. In this case, one of the substrates may be transparent.

On the first substrate 1, a strip-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 includes the liquid crystal layer 3 and the discharge region 4
Without the dielectric film 6, there is a risk that 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.

Since the dielectric film 6 is formed of a dielectric material, the dielectric film 6 itself functions as a capacitor. Therefore, the electric coupling between the discharge region 4 and the liquid crystal layer 3 is sufficiently ensured, and the electric charge is maintained. In order to suppress the two-dimensional diffusion, it is better to be as thin as possible.

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 disposed 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.

First, the display operation will be described with an example of an electrode configuration in which an anode electrode and a cathode electrode are provided as a pair.

First, a plurality of strip-shaped electrodes 5 having a predetermined width are formed on the main surface 1a of the first substrate 1 facing the second substrate 2. 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, also on the main surface 2a of the second substrate 2 facing the first substrate, a discharge electrode group 7 is formed. 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} ··· K
consists _n-1, K _n, the discharge electrodes are formed by these pairs.

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, the electrode 5 of the first substrate 1 is provided with a first driver constituted by a data driver circuit 9 and an output amplifier 10.
Signal applying means is connected, and an analog voltage output from each output amplifier 10 is supplied as a liquid crystal drive signal.

On the other hand, in the discharge electrode group 7 on the second substrate 2, each of the cathode electrodes K ₁ , K ₂ , K _3.
The _n-1, K _n, the second signal applying means and a data strobe circuit 11 and output amplifier 12 is connected, a pulse voltage output from the output amplifier 12 is supplied as a data strobe signal . In each anode _{A 1, A 2, 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.

Assume 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, the cathode electrode K of the second substrate 2_Two To
When the data strobe signal is applied,
The anode electrode A_Two And cathode
Pole K _Two Gas is ionized by the discharge between
Pole A_Two , K_Two Along the ionized region (discharge plasma
C) occurs. Then, a so-called plasma switch
Electrode 5 and anode electrode A_Two Is electrically
Connected state, plasma when viewed from a circuit perspective
・ Switch S_Two Is turned on.

As a result, the analog voltage supplied to the electrode 5 is stored in the capacitor model 14 in the column where the cathode electrode K ₂ is strobed. 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.

However, in the present embodiment, an n: 1 interlace operation is performed. Therefore, the display operation will be described by taking 2: 1 interlaced scanning as an example.

In 2: 1 interlaced scanning, scanning lines are scanned at a ratio of one line to two lines. For example, in an even field, even lines are sequentially selected, and in an odd field, odd lines are selected. That is, in the even-numbered field, the even-numbered cathode electrode K
_2, K _4, data strobe signal to the K ₆ · · · are sequentially applied, in the odd field, data strobe signal is sequentially applied to the odd-numbered cathode electrodes _{K 1, K 3, K 5} ···.

At this time, each cathode electrode K₁ , K_Two , K
_Three ... K_n-1 , K_n Mark the data strobe signal on the
In addition, the anode electrode A₁ , A_Two , A_Three ... A
_n-1 , A _n Discharge occurs between and discharge plasma is generated
However, the width of the discharge plasma region is determined by the scanning unit (scanning).
That is, it is set to be twice or more the pitch p) of the discharge electrode group 7.
I have.

The expansion of the discharge plasma region is governed by the type and pressure of the gas sealed in the discharge region 4, the distance and shape of electrodes for discharge, the gap distance of the discharge region 4, and the like. By setting the values to appropriate values, it is possible to achieve the above-mentioned spread.

That is, first, as is well known, as for the gas pressure of the gas sealed in the discharge region 4, the higher the pressure, the smaller the mean free path of the charged particles and the more the localization tendency. Therefore, by setting this gas pressure to an appropriate value, it is possible to control the discharge plasma to an appropriate spread.

However, when 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.

Also, by selecting the gap interval W of the discharge region 4, the effective spread of the discharge plasma can be controlled to some extent.

As specific conditions, for example, the electrode pitch p = 0.4 mm, the gap interval W of the discharge region 4 = 0.4
mm, the type of gas to be filled is Ne gas (+ 0.5% Ar),
By setting the gas pressure to 120 Torr, the discharge plasma area could be made about twice the scanning unit.

FIGS. 6 and 7 show the discharge plasma scanning.
Is shown. For example, in an even field, as shown in FIG.
And the even-numbered cathode electrode K_{i + 1} , K_{i + 3} , K
_{i + 5}... (where i is an odd number)
The strobe signal is supplied and the discharge
A gap region P is formed. That is, the cathode electrode K
_{i + 1} A in FIG. 6 indicates a state in which the cathode electrode K is on._{i + 3} But
The ON state is indicated by B in FIG._{i + 5} Is on
The state is C in FIG.

At this time, since the discharge plasma region P which is sequentially scanned is about twice as large as the electrode pitch p, the liquid crystal layer 3 is changed according to the analog voltage applied to the electrode 5 in all regions on the screen. Driven.

On the other hand, consider writing in an odd field.
Then, in this case as well, as shown in FIG.
Sword electrode ・ ・ ・ K_{i + 2} , K_{i + 4} , K_{i + 6} ... in order
The data strobe signal is supplied and released every other line.
An electric plasma region P is formed. That is, the cathode electrode
Pole K_{i + 2} A in FIG. 7 indicates the on state of the cathode electrode K.
_{i + 4} B is the on state in FIG._{i + 6} But
The ON state is C in FIG.

Therefore, even in an odd field,
For the same reason as in the even field, the liquid crystal layer 3 is driven in all regions on the screen.

As described above, in both the even field and the odd field, the selection of the cathode electrode is performed every other line. However, since the discharge plasma region has the width of two lines, all the pixels on the screen are It is completely refreshed within one field. Therefore, the problem of deterioration of the dynamic resolution due to the interlacing does not occur at all.

Further, since the reversal of the polarity of the liquid crystal layer 3 is completed in one frame cycle, the flicker of two frame cycles, which has conventionally been a problem, does not occur.

Furthermore, the drive circuit only needs to perform simple interlaced scanning, and it is not necessary to take any special measures for dynamic resolution and measures against flicker.

In the above description, the case of the 2: 1 interlace has been described. However, in the case of the n: 1 interlace, the same operation can be performed by setting the discharge plasma area to at least n times the scanning unit. It is feasible.
For example, in the case of a 3: 1 interlace, the discharge plasma area may be at least three times the scanning unit, and in the case of a 4: 1 interlace, the discharge plasma area may be at least four times.

In the above, the display operation has been described by taking as an example the case where a discharge electrode is constituted by a pair of an anode electrode and a cathode electrode. However, in the present invention, the electrodes arranged at equal intervals are arranged in the anode electrode for each field. Or as a cathode electrode so as to obtain the same effect.

For example, as shown in FIGS. 8 and 9, it is assumed that discharge electrodes... E _i , E _{i + 1} , E _{i + 2} .

These discharge electrodes: E _i , E _{i + 1} , E
_{i + 2} ... are connected to a DC power supply via a resistor and grounded via a driving transistor, and operate as an anode or as a cathode by turning on / off these driving transistors. . Therefore, each discharge electrode... E _i , E _{i + 1} , E _{i + 2.}
The interval p between them is a scanning unit.

In the image display device configured as described above,
For example, when the drive transistor of the discharge electrode E _{i + 1} is turned on, it operates as an anode, and the other discharge electrodes operate as cathodes.

As a result, discharge occurs between the discharge electrode E _{i + 1} and the discharge electrode E _{i and} between the discharge electrode E _{i + 1} and the discharge electrode E _{i + 2} , and the electrode interval, that is, the scan unit p Is generated twice as much as discharge plasma.

That is, in the 2: 1 interlace scanning, the even-numbered discharge electrodes in the even-numbered fields are used.
The driving transistors connected to E _{i + 1} , E _{i + 3} , E _{i + 5} ... Are sequentially turned on, and as shown by A, B, and C in FIG. The generated discharge plasma P is generated. Similarly, in the odd-numbered field, the driving transistors connected to the odd-numbered discharge electrodes... E _{i + 2} , E _{i + 4} , E _{i + 6} .
As shown by B and C, discharge plasma P having a width of two scanning units is also generated sequentially.

Therefore, also in this case, all the pixels on the screen are completely refreshed within one field.

[0067]

As is apparent from the above description, in the image display apparatus of the present invention, when the interlaced driving is performed, a plurality of discharge electrodes are arranged at substantially equal intervals in the discharge space at the arrangement pitch of the scanning lines. And one scan line is shifted by one scanning line for each field, and sequential scanning is performed with different combinations of discharge electrodes. Therefore, the entire screen can be refreshed for each field, and when an interlace operation is performed. It is possible to solve the problem of the degradation of the dynamic resolution and the flicker that occur.

At this time, there is no burden on the drive circuit, which is very advantageous in terms of manufacturing cost and the like.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a main part of an example of an image display device 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 example of an image display device 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.

FIG. 6 is a schematic diagram showing a state of scanning of discharge plasma in an even field.

FIG. 7 is a schematic diagram showing a state of scanning of discharge plasma in an odd field.

FIG. 8 is a schematic diagram showing a state of scanning of discharge plasma in an even field in an example to which the present invention is applied.

FIG. 9 is a schematic diagram showing a state of scanning of discharge plasma in an odd field in an example to which the present invention is applied.

FIG. 10 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, 2nd board | substrate, 3 liquid crystal layers (electro-optic material layer), 4 discharge areas, 5 electrodes, 7 discharge electrode groups

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI H04N 5/66 101 G09G 3/28 Z

Claims (1)

(57) [Claims] 1. An image display apparatus for displaying an image by sequentially scanning a linear discharge plasma region along a scanning line, wherein a plurality of discharge electrodes are arranged in a discharge space at substantially equal intervals at an arrangement pitch of the scanning lines. And an interlaced drive in which scanning is sequentially performed with a combination of different discharge electrodes shifted by one scanning line for each field, and interlaced driving is performed.