Embodiment
In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
See also Fig. 1 and Fig. 2, show the manufacturing approach of the LCD of present embodiment, it may further comprise the steps:
(a) first glass substrate 12 and second glass substrate 14 are provided, and on two glass substrates 12,14, form electrode pattern and oriented layer;
(b) at first glass substrate 12 and second glass substrate, 14 periphery silk-screen encapsulating materials;
(c) on first glass substrate 12, arrange gap particles 19;
(d) first glass substrate 12 and 14 contrapositions of second glass substrate are fitted, and under the pressure of 0.06-0.08MPa, carry out hot-pressing processing, form liquid crystal cell;
(e) liquid crystal 18 is injected liquid crystal cell and flattens processing, obtain LCD 10.
Usually (Indium Tin Oxides, ITO) the indium tin oxide target electrode pattern is as shown in Figure 2, comprises the row electrode 15 and the column electrode 13 that are formed at respectively on first, second glass substrate 12,14 to form ITO on two glass substrates 12,14.Second glass substrate 14 is a light transmission glass preferably, can be formed with filter coating on it, therefore is referred to as CF (Color Filter) glass sometimes.After forming electrode pattern, then, be generally organic polymer oriented material such as polyimide, to form oriented layer (figure does not show) at ranks electrode surface coating oriented material.Usually also need carry out friction treatment then, for example press specific direction friction orientation layer, to let the liquid crystal of back perfusion arrange along this frictional direction with flannelette class material to oriented layer.Concrete direction of orientation design load is relevant with the liquid crystal distortion angle, for example, if realize high steepness, then will strengthen the liquid crystal distortion angle accordingly.
In the step (b), adopt silk screen print method with encapsulating material 161 and 162 like silk-screens such as epoxy resin in first glass substrate 12 and second glass substrate, 14 peripheries, the frame glue 16 that at the back two glass substrates 12,14 is sealed with formation.Usually need to reserve a breach, so that by this breach perfusion liquid crystal 18.In the silk-screen process, mix the silicon ball in the encapsulating material, and mix a certain amount of gold goal as levels electrode conduction material as support.The particle diameter of silicon ball is larger than gap particles 19.The particle diameter of gold goal is larger than the silicon ball, to guarantee conducting levels electrode.Usually also can be on first glass substrate 12 the silk-screen conducting resinl, with the levels electrode conduction.After silk-screen was accomplished, further the encapsulating material to silk-screen carried out preliminary drying, makes the solvent evaporates of encapsulating material, made its drying to increase its adhesiveness and wearing quality surperficial with ito glass.
Then; On first glass substrate 12, evenly arrange gap particles 19; The particle diameter of gap particles 19 is about several microns; Present embodiment adopts particle diameter to be about 5.5 ± 0.1 microns gap particles 19, and the back is processed liquid crystal cell and leaned on this gap particle 19 to support, and the thick or box spacing of box is also determined by the particle diameter of gap particles 19.The layout density of gap particles 19 is 180-250/mm
2
To pass through first glass substrate 12 and second glass substrate 14 of above-mentioned each step then and adjust the position, and their contrapositions fitted, and under the pressure of 0.06-0.08MPa, carry out hot-pressing processing, form liquid crystal cell through alignment mark.After two glass substrates 12,14 were fitted, available glue such as ultra-violet curing glue were tentatively bonding with them, get in the hot pressing furnace after the precompressed again.The effect of hot pressing furnace is to make frame glue full solidification, and makes gap particles 19 that certain deformation take place, and this deformation is deformation set; After hot pressing, carry out the heat baking; Heat baking to a certain degree can make gap particles 19 rebound slightly, but can not be returned to original size, but more smaller than initial value.The ratio of compressed degree of gap particles and bounce-back is the key of the thick stability of box.
Three processes take place in manufacturing process general gap particles: at first anti-in hot pressing, gap particles 19 receives maximum pressure, is compressed and is deflected into maximum.Then, hot pressing pressure discharges, and quenches in uniform temperature (temperature when being usually less than hot pressing), gap particles 19 resiliences, but can not spring back to initial particle, rebound value is relevant with gap particles 19 hardness own.Different types of gap particles 19 rebound values are different.
In manufacturing process, on-load pressure is P (gf/mm during the thick leveling of hot-pressing processing or box
2), the compression deformation rate of spacer particle material is A (u/gf); Spacer particle arranges that density is that N is (individual/mm
2);
Then single spacer particle is stressed: P/N;
Deflection: AP/N generally gets N=180/mm
2
Hot pressing pressure P=0.70-0.80kgf/mm
2
Gap particles 10% elastic modulus: 50-70kgf/mm
2
Can know by the Hiramatsu formula: S=2.8p/PI*d
2
Wherein S is elastic modulus (kgf/mm
2), p is load (kgf), d is mean diameter (micron);
The deformation rate curve of gap particles is a nonlinear curve, is an One-place 2-th Order curve, brings known point into and calculates, and can obtain quafric curve and be approximately: d (displacement)=0.01798+2.666p-1.061p
2, wherein p is the pressure on the single particle.Can know that by this curve the deformation rate of gap particles is acted on the influence of particle upward pressure.Therefore, through the pressure of corrective action in particle, the deformation rate of may command gap particles is selected suitable box spacing thus.
Yet in the actual production manufacture process, because the fluctuation of equipment and material, the box spacing is difficult to keep a certain setting value, and normally fluctuation among a small circle.In the manufacturing approach of present embodiment, when hot pressing pressure is 0.07MPa, can this fluctuation be reduced to minimum, can reach the most stable box-like attitude of one-tenth, its box is thick evenly, the good stability behind the one-tenth box.In manufacture process, receive external force and do the time spent and change very for a short time, fraction defective can be reduced to 0.3-0.5% by the 7-10% before improving, and it is obvious to improve effect.
Particularly, the hot pressing of two glass substrates in hot pressing furnace that posts is divided into two sections: the phase one, temperature is made as 60-100 ℃, and present embodiment adopts 80 ℃, and hot pressing pressure is made as 0.06-0.08MPa, is preferably 0.07MPa, and the time is 60 minutes.Subordinate phase, temperature are set to 140-180 ℃, and present embodiment adopts 170 ℃, and hot pressing pressure is identical with the phase one, and the time is 135 minutes.Remove pressure then, make the hot pressing furnace natural cooling, form liquid crystal cell.It is understandable that two stage hot pressing pressure also can be inequality, and hot pressing time is not limited to the time shown in the present embodiment, concrete hot pressing time can be according to actual needs and effect and make change.
In step (e), earlier liquid crystal is injected in the liquid crystal cell through the breach of reserving, flatten processing again, promptly unsealed liquid crystal cell is applied certain pressure, make the thick maintenance steady state (SS) of whole box, be compressed again at this process intermediate gap particle.Wherein, leveling pressure is about 0.60-0.80Kgf/cm
2, present embodiment adopts 0.70Kgf/cm
2Through increasing leveling pressure, can reduce the fraction defective that causes owing to the thick instability of box greatly, further improve the stability of LCD.
Leveling pressure is chosen 0.30Kgf/cm respectively
2, 0.50Kgf/cm
2, 0.70Kgf/cm
2, the liquid crystal cell to these three kinds of condition manufacturings carries out fail-test simultaneously, and the result is as shown in table 1 below.
The liquid crystal cell fail-test performance table that the different leveling of table 1 pressure is made down
Pressure P (kgf/cm
2)
|
The thick d of box (micron) |
Reduced size (micron) |
Compressibility (%) |
Stability result |
0.30 |
?5.46 |
0.04 |
0.73% |
The poorest |
0.50 |
?5.43 |
0.07 |
1.27% |
Generally |
0.70 |
?5.4 |
0.1 |
1.82% |
Best |
Test findings is found, is 0.70kgf/mm at leveling pressure
2The time, liquid crystal cell stability is best.
In addition, present embodiment also comprises the product of distance and double refractive inde between the box of adjusting liquid crystal cell, also is the step of the optical path difference of liquid crystal cell, and the optical path difference of liquid crystal cell is adjusted at 780 nanometers between 870 nanometers that present embodiment adopts 830 nanometers.For example, the adjustment of this liquid crystal cell optical path difference can be through allocating the double refractive inde of liquid crystal cell between 0.144-0.161, and present embodiment adopts 0.158, and the box spacing of liquid crystal cell adopts 5.5 ± 0.1 microns.
Usually for CSTN type liquid crystal indicator, the parameter of decision display effect is the optical path difference of liquid crystal cell, i.e. the product of box spacing (d) and double refractive inde (Δ n).For common twisted nematic liquid crystal layer, the OFF state transmitance of incident light is decided by the e-light (perpendicular to optical axis direction) of elliptically polarized light and the interference effect of o-light (being parallel to optical axis direction).For the result who interferes, transmittance curve d Δ n shows as has maximum value and minimal value.Use for TN type LCD, have two d Δ n windows to use, its first and second minimal values window is respectively d Δ n=0.4-0.55 micron and d Δ n=1.0-1.2 micron.
For the maximum d Δ n value of process window, maximum d Δ n place should be chosen and just best display effect can be obtained, change in the d value simultaneously, when promptly causing d Δ n fluctuation, in bigger dynamic range, transmitance does not have too big variation.
But in the process that liquid crystal is made; Because the fluctuation of equipment and material, the liquid crystal cell spacing constantly changed in the different production time, and liquid crystal material is more stable usually; Reach design load so guarantee optical path difference d Δ n; The method that present embodiment is taked is that the Δ n through the adjustment liquid crystal realizes that through dynamic adjustment Δ n, the d Δ n of the product that guarantees to produce each time is in the process window maximum of points of photoelectric curve; Thereby fluctuation is reduced to minimum, can uses the photoelectric curve proving installation (as using 5200) of LCD to measure the photoelectric characteristic curve of the LCD of present embodiment in the practical implementation method.At first, n will produce suitable light path difference through adjustment d Δ, and we choose d Δ n=830nm herein through overtesting, can realize better effects.
See also Fig. 2, through after the above-mentioned steps, can make LCD as shown in Figure 2 10, this LCD 10 comprises first glass substrate 12 and second glass substrate 14, and is ordered in the liquid crystal 18 between two glass substrates 12 and 14.First glass substrate 12 and second glass substrate, 14 edges are coated with sealing frame glue 16.Have spacer particle 19 supports between two glass substrates 12 and 14 and isolate liquid crystal 16.
Owing to when this LCD 10 is made hot pressing pressure is reduced to 0.06-0.08MPa; Can make liquid crystal cell under external force; It is minimum that the variation of its box spacing will reach; The stability of strengthen box spacing thus improves the stability and the reliability of LCD 10, strengthens the stability of its liquid crystal display.
The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.