JP3341010B2 - Liquid crystal display device deformation / strain / stress calculation method and liquid crystal display device diagnosis method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calculating the deformation, strain and stress of a liquid crystal display device which is formed by laminating thin members such as a polarizing plate, a glass substrate, a transparent electrode, a color filter and a liquid crystal. The present invention relates to a method for diagnosing a liquid crystal display device using a calculation result.

[0002]

2. Description of the Related Art In recent years, prior art relating to computer simulation of a liquid crystal display device has been disclosed. For example, JP-A-10-253969,
Japanese Patent Application Laid-Open No. H11-305181 describes a simulation technique using a finite element method. Also,
Japanese Patent Application Laid-Open No. 6-11063 discloses a proposal of an appropriate spacer particle size for maintaining a uniform distance between a glass substrate on the color filter layer side and a glass substrate opposed thereto.

A liquid crystal display has a structure as shown in a sectional view of FIG. 1 is a polarizing plate, 2 is a color filter glass substrate, 3 is a color filter layer, 4 is a transparent electrode,
Reference numeral 5 denotes a liquid crystal layer, 6 denotes a TFT array glass plate, 7 denotes a transparent electrode, 8 denotes a polarizing plate, 9 denotes a spacer, 10 denotes a sealing portion for containing liquid crystal, and 11 denotes a cell gap which is an interval between the transparent electrodes 4 and 7. ing.

A liquid crystal display device encloses liquid crystal between two structures in which thin plate-shaped members such as polarizing plates 1 and 8, glass substrates 2 and 6, a color filter layer 3, and transparent electrodes 4 and 7 are laminated. A large number of spherical spacers 9 for keeping the distance between the glass substrates 2 and 6 constant are dispersed in the liquid crystal. The two laminated materials are applied with pressure from the outside of the substrate until the adhesive of the seal portion 10 is hardened, and after the hardening, are subjected to the repulsive force of the internal spacer 9 which has undergone compression elastic deformation.

Since the repulsive force varies depending on the location, the interval of the cell gap 11 in which the liquid crystal is sealed is not uniform. For this reason, contrast unevenness such as a washout phenomenon occurs. Alternatively, a part of the spacers 9 bites into the protective film of the color filter layer 3 to cause distortion in the glass substrate, resulting in color unevenness.

One proposal for analyzing the washout phenomenon by computer simulation and automatically achieving uniform glass substrate spacing is disclosed in JP-A-10-25.
Japanese Patent No. 3969 discloses a method of analyzing a two-dimensional problem by replacing a large number of spacers in a liquid crystal, which is difficult to model, with an equivalent Young's modulus. Also, Japanese Unexamined Patent Application Publication No.
No. 063 discloses a method of increasing the particle diameter of the spacer at the outer peripheral portion of the glass substrate to prevent the protective film from biting.

Although such a simulation is simple, it is considered that there is a problem in accuracy because the shape of the spacer, the distribution density, and the material properties must be assumed. In addition, spacers are not always arranged uniformly, and it is considered that dense places and sparse places are mixed, and it is not clear whether analysis in a two-dimensional problem can be performed. Also,
It is difficult to confirm whether or not the extremely fine particle size of the spacer is properly changed depending on the location after assembling the apparatus.

[0008]

SUMMARY OF THE INVENTION A polarizing plate, a glass substrate,
It is clear what kind of deformation state of each member of the liquid crystal display device composed of transparent electrodes, color filters, liquid crystal, etc., especially the glass substrate, and what kind of strain and stress is generated by the inside. Absent. If the gap of the cell gap is not uniform due to the deformation of the glass substrate, uneven contrast such as a washout phenomenon occurs. Also, due to the deformation of the glass substrate, the distribution of internal strain and stress is not uniform, but places where the strain and stress are large lead to separation between members and breakage of members, resulting in display unevenness. Conceivable.

According to the present invention, in order to determine the cause of such display unevenness, the deformation of each part of the member of the liquid crystal display device is performed by combining the simulation by the finite element method based on the measurement data of the surface shape of the measurable member. The purpose of the present invention is to calculate strain / stress, to investigate the cause of display unevenness and to take countermeasures, and to make use of this data to diagnose a defect of the liquid crystal display device and the possibility of display unevenness.

[0010]

According to the present invention, there is provided a liquid crystal display comprising a polarizing plate, a glass substrate, a transparent electrode, a color filter, a liquid crystal, etc. Measure the surface shape of the measurable member, determine the surface displacement by comparing it with the pre-measured no-load reference shape before assembling the device, and use the finite element method to determine the surface displacement and the internal surface of the liquid crystal display device from the result. This is a deformation / strain / stress calculation method for a liquid crystal display device that calculates displacement / strain / stress in all regions.

According to the present invention, the shape of a liquid crystal display device including a polarizing plate, a glass substrate, a transparent electrode, a color filter, a liquid crystal, and the like under load after assembly is measured.
Even when the spacers are not arranged uniformly and dense and sparse places are mixed, the nonuniformity of the cell gap interval can be accurately grasped three-dimensionally.
Using this measurement result, a finite element simulation is performed to clarify the deformation, strain, and stress in all areas on the surface and inside. Therefore, the cause of liquid crystal display unevenness and quantitative measures are implemented. It becomes possible.

Further, the present invention measures only the shape of a measurable member surface of a liquid crystal display device comprising a polarizing plate, a glass substrate, a transparent electrode, a color filter, a liquid crystal and the like, and based on the measurement result, The surface shape of another unmeasurable member can be obtained by extrapolating using the thickness of each member known in advance.

According to the present invention, it is possible to measure a liquid crystal display device having a structure in which a liquid crystal is sealed between two laminated structures in which thin flat members such as a polarizing plate, a glass substrate, a transparent electrode, and a color filter are laminated. Only the surface shape of the member is measured, and the shape of the other member surface that cannot be measured is extrapolated using the known thickness of the device. This makes it possible to clarify the state of deformation due to load and the occurrence of strain / stress due to it, and to precisely investigate the cause of display unevenness of the liquid crystal and take countermeasures.

Further, the present invention is characterized in that in measuring the surface shape of a member, a pixel position where a transparent electrode signal line arranged in a matrix on a liquid crystal display device intersects is used as a measurement position. Accordingly, in the measurement of the member surface shape, the pixel position where the transparent electrode signal line intersects is used, so that it is not necessary to mark the measurement target with the mark indicating the measurement position.

Further, the present invention is characterized in that a finite element method mesh having a representative point of each member as a node is constructed, the displacement at this node is analyzed as a known amount, and an equivalent nodal force at each node is obtained. Further, the measurement position of the member surface shape may be used as a node.

According to the present invention, a finite element method mesh having a representative point of each member as a node is formed, and a finite element analysis is performed using the displacement at this node as a known amount. Is used, the number of nodes required for the analysis is only several hundreds, and it is sufficient to arrange the nodes only on the surface of each member, and the shape measurement can be limited to only the surface of each member. Further, since the finite element analysis is performed using the displacement as a known amount, the equivalent nodal force at each nodal point can be obtained. As a result, it becomes clear in detail what kind of load the liquid crystal display device receives in the assembled state.

Further, the present invention makes it possible to investigate the cause of display unevenness of a liquid crystal display device and take countermeasures by using the obtained deformation, strain and stress, and furthermore, it is possible to break / break members, peel off members, etc. It is characterized in that a diagnosis is made as to the nature and the possibility of display unevenness.

According to the present invention, it is possible to investigate the cause of display unevenness of a liquid crystal display device due to deformation, strain, and stress, and to take countermeasures. In addition, by comparing the calculated allowable values such as breakage or breakage of each member or separation between members from each other, it is possible to diagnose the occurrence of these and the possibility of occurrence of display unevenness. In particular, it is desired that the glass substrate, which is the most important in terms of strength, in the liquid crystal display device be as thin as possible in order to reduce the weight, but the thinner, the lower the strength. According to the present invention, it is also possible to determine the limit value of the thickness of the glass substrate

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for calculating deformation / strain / stress of a liquid crystal device according to the present invention will be described below with reference to FIGS. FIG. 2 shows a finite element method model of a glass substrate on a side including a color filter layer of a liquid crystal display device to be analyzed when performing a simulation according to an embodiment of the present invention. The illustrated model is a diagram imagining an example of a deformed state when receiving a load due to device assembly.

As shown in FIG. 1, the model of the liquid crystal display device comprises a polarizing plate 1, a color filter glass substrate 2, a color filter layer 3, a transparent electrode film 4, a node 20, and a finite element mesh 21. The node 20 of the polarizing plate 1 is a lattice point selected as a representative point of the measurement position when measuring the surface shape. All regions are divided into elements by a solid finite element mesh 21 using grid points of each member as nodes of the model.

FIG. 2 is a flowchart showing a procedure for measuring deformation, strain, and stress using the finite element model of FIG. FIG. 3 is a diagram schematically illustrating a procedure for calculating deformation, strain, and stress corresponding to the flowchart of FIG. 2 using a cross-sectional view of a finite element method model and basic calculation formulas. Hereinafter, the procedure for measuring the deformation, strain, and stress will be described with reference to FIGS. In the present specification, the same reference numerals denote the same or corresponding components.

1. First, the shape of the outer surface of the liquid crystal display device, such as the polarizing plate, the glass substrate, the color filter layer, the transparent electrode film, etc. before assembly without load is measured by a known method (step S1). 2. Next, the shape of only the outer surface that can be measured under a load after the assembly of the device is measured (step S2). 3. By comparing the surface shapes before and after the above assembling, displacement amounts of some lattice-like representative points set on the liquid crystal panel surface are obtained (step S3). 4. Next, the amount of displacement of a lattice point inside the apparatus corresponding to the above-mentioned surface lattice point is obtained by extrapolation from the previously measured surface shape of each component (step S4).

5. Next, a finite element mesh in which the lattice points provided on the surface and the inside are nodes of the finite element method is generated (step S5). The type of the finite element shown in step S5 is a three-dimensional solid element (solid element), but a laminated shell element can also be used. 6. Since the displacement amounts of all the nodes have been determined, the finite element analysis is performed using these as known amounts, so that the equivalent node forces of all the nodes are obtained (step S6). 7. Next, for each element, the strain of each element is determined using the strain-displacement conversion matrix, and the stress of each element is further determined using the stress-strain conversion matrix (step S7).

FIG. 4 shows an example of setting grid points and nodes of the finite element method model. The pixels of the transparent electrodes 7 or R, G, B arranged regularly in a grid pattern can be used as nodes of the finite element method model. Also, the transparent electrode 7 or R, G,
The pixel B can be used as reference coordinates. Also, R, G, B
Since the pixel and the transparent electrode 7 can also be measured from the polarizing plate 1 side, they can be used as measurement positions of the surface shape of the polarizing plate 1, and there is no need to particularly provide measurement position coordinates.

FIG. 4 shows an example in which a pixel position 22 where a transparent electrode signal line intersects is used as a grid point and reference coordinates of a transparent electrode film. The lattice point of the polarizing plate 1, the measurement position (point 20), and each lattice point (+ point) on the other members are positions shifted from the reference points by the plate thickness of each member in the normal direction. Since the thickness of each member is extremely thin, such extrapolation is possible.

When a load is applied to the liquid crystal display device, which point is displaced to which position when no load is applied can be easily obtained from the above coordinate position. However, it is necessary to determine a common reference position before and after the deformation. A plane that passes through the four corners of the four corners of the liquid crystal display or a plane that includes two opposing sides of the surface is set as a reference plane, and the planes are obtained by superimposing the planes before and after deformation (see step S3 in FIG. 3). This calculation is possible because a thin laminated structure such as a liquid crystal display device is mainly subjected to out-of-plane bending deformation and negligible in-plane expansion and contraction.

The present invention relates to a PDP (Plasma Display Panel) display device, an organic EL
(Electroluminescence) It can also be applied to element display devices and the like. FIG. 5 shows a PDP display device, and FIG. 6 shows an organic EL device display device.

Further, the present invention can be used to investigate the cause of display unevenness of a liquid crystal display device caused by deformation, strain, and stress by using the calculated result, particularly, deformation, strain, and stress of an internal member, and to take countermeasures. . In particular, it is desired that the glass substrate, which is the most important in terms of strength, in the liquid crystal display device be as thin as possible in order to reduce the weight, but the thinner, the lower the strength. According to the present invention, the limit value of the thickness of the glass substrate can be determined. In addition, by comparing the calculated allowable values such as breakage or breakage of each member or separation between members from each other, it is possible to diagnose the occurrence of these and the possibility of occurrence of display unevenness.

[0029]

According to the present invention, a polarizing plate, a glass substrate,
Displacement, strain and stress on the entire surface and inside of the assembled liquid crystal display device consisting of transparent electrodes, color filters, liquid crystal, etc. can be calculated by a method combining surface shape measurement and finite element simulation. . Further, since the finite element method is used, it is possible to know what kind of load is applied to each member due to the load at the time of assembly.

According to the present invention, the physical
Since the mechanical characteristics are clarified in detail, it is possible to investigate the cause of display unevenness such as uneven brightness and uneven color caused by deformation and distortion, and to take countermeasures. Further, since the detailed stress distribution of each member can be known, it is possible to predict the possibility of peeling of the interface between each member and the member in a place where the stress is high or the damage of the member. Measures for preventing a decrease in rigidity due to an increase in the size of the liquid crystal display device can be quantitatively implemented.

[Brief description of the drawings]

FIG. 1 is an image diagram showing an example of a finite element method model of a glass substrate including a color filter layer of a liquid crystal display device used by a calculation method of the present invention, which is deformed under load.

FIG. 2 is a flowchart illustrating a method for calculating deformation / strain / stress according to the present invention.

FIG. 3 is an explanatory diagram conceptually showing a calculation procedure of deformation, strain, and stress corresponding to the flowchart of FIG.

FIG. 4 is a diagram illustrating an example of setting surface shape measurement points and nodes of a finite element method model according to the present invention.

FIG. 5 is a diagram showing a PDP display device to which the present invention is applied.

FIG. 6 is a diagram showing an organic EL element display device to which the present invention is applied.

FIG. 7 schematically shows the structure of a standard liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polarizer 2 Color filter glass substrate 3 Color filter layer 4 Transparent electrode 5 Liquid crystal layer 6 TFT array glass substrate 7 Transparent electrode 8 Deflector 20 Grid point of surface member, measurement position 21 Finite element mesh 22 Intersection of transparent electrode signal lines Pixel position + grid point

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-11-305181 (JP, A) JP-A-9-80446 (JP, A) JP-A-6-186141 (JP, A) JP-A-10- 253969 (JP, A) JP-A-3-99215 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 21/32 G01L 1/00 G02F 1/1333

Claims (5)

(57) [Claims] In a liquid crystal display device, the position of a surface shape of a measurable member can be measured at a load after assembly of the device.
Of the transparent electrode signal lines arranged in a matrix.
Using pixels at the intersection only measures the surface shape,
The surface displacement is determined by comparison with the reference shape measured beforehand when no load is applied before assembling the device, and the displacement, strain, and stress on the entire surface and inside of the liquid crystal display device are calculated from the result by the finite element method. A method for calculating deformation / strain / stress of a liquid crystal display device. 2. A measurement of the surface shape of claim 1, only the measured surface profile of measurable member, a plate thickness of each member is known in advance about the surface shape of the other member are stacked A method for calculating the deformation, strain, and stress of a liquid crystal display device, wherein the shape is obtained by extrapolating the shape. 3. When the finite element method is used, a finite element method mesh having a representative point of each member as a node is constructed, the displacement at this node is analyzed as a known amount, and an equivalent nodal force at each node is obtained. 3. The method for calculating deformation, strain and stress of a liquid crystal display device according to claim 1 or 2, wherein: 4. In a crystal display device, as a measurement position of a surface shape of a measurable member at the time of loading after assembling the device, a transparent electrode signal line arranged in a matrix is used as a measurement position .
Using pixels at the intersection only measures the surface shape,
The surface displacement is obtained by comparing with the reference shape at the time of no load, which is measured in advance before the device is assembled, and the displacement, strain, and stress on the entire surface and inside the liquid crystal display device are calculated from the result by the finite element method. And diagnosing the liquid crystal display device based on the result. 5. The method according to claim 4, wherein the measurement of the surface shape
Only the surface shape of the measurable member is measured and laminated
Each member whose surface shape is known in advance
Extrapolation using the thickness of
A method of diagnosing a liquid crystal display device.