Patent Application
20200089031
The present invention relates to a method of producing a liquid crystal panel.
An example of a conventionally known method of producing a liquid crystal panel is one described in Japanese Patent Application No. 5980104 The method of producing a liquid crystal panel described in Japanese Patent Application No. 5980104 includes a step of forming a columnar spacer on a main surface of a CF substrate and then measuring the height of the columnar spacer, a step of bonding a TFT substrate and the CF substrate to each other and then measuring a gap between the TFT substrate and the CF substrate, and a step of judging whether or not the liquid crystal panel is good based on a difference between the measured height of the columnar spacer and the measured gap.
In recent years, a liquid crystal panel may have been required to be thinned. In the case, a glass substrate constituting the produced liquid crystal panel has been subjected to slimming processing. Accordingly, diversity tends to increase with respect to the plate thickness of the glass substrate constituting the liquid crystal panel. However, the above-described Japanese Patent Application No. 5980104 does not consider the plate thickness of the glass substrate. When the number of columnar spaces to be installed, for example, is made constant regardless of the plate thickness of the glass substrate being diversified, there have been problems. For example, a liquid crystal material is accumulated on the lower end side of the produced liquid crystal panel by gravity when the liquid crystal panel is leaned so that a display failure occurs.
The present invention has been completed based on the above-described circumstances, and is directed to making it difficult for a display failure to occur even if the plate thickness of a substrate is diverse.
(1) An aspect of the present invention is a method of producing a liquid crystal panel, the method including an abutment area determination step for determining, within a range sandwiched between an approximate curve obtained by plotting, when a difference between a height of a spacer that is interposed between a pair of substrates with a liquid crystal layer sandwiched therebetween and holds a distance between the pair of substrates by abutting on its counterpart and the distance is set as a reference value, an upper-limit value of a substantial abutment area per unit area on the counterpart for each of a plurality of plate thicknesses of the pair of substrates that differ from one another and a straight line on which the abutment area is set to 230 μm2/mm2 regardless of the plate thickness, the abutment area depending on the plate thickness, a spacer formation step for forming the spacer to have the abutment area determined in the abutment area determination step, and a bonding step for bonding the pair of substrates to each other.
(2) The aspect of the present invention is the method of producing the liquid crystal panel in which in the abutment area determination step, a minimum value and a maximum value related to the difference are found, and a range between the minimum value and the maximum value is set as the reference value in addition to the configuration in the above-described item (1).
(3) The aspect of the present invention is the method of producing the liquid crystal panel, in which in the abutment area determination step, the reference value is set in a range from 0.13 μm to 0.17 μm in addition to the configuration in the above-described item (2).
(4) The aspect of the present invention is the method of producing the liquid crystal panel, in which in the abutment area determination step, the reference value is set to 0.15 μm in the configuration in the above-described item (3).
(5) The aspect of the present invention is the method of producing the liquid crystal panel, in which in the abutment area determination step, the abutment area is determined depending on the plate thickness within a range sandwiched between the approximate curve and a straight line on which the abutment area is set to 234 μm2/mm2 regardless of the plate thickness in addition the configuration in any one of the above-described items (1) to (4).
(6) The aspect of the present invention is the method of producing the liquid crystal panel, in which in the abutment area determination step, the abutment area is determined depending on the plate thickness within a range sandwiched between the approximate curve and a straight line on which the abutment area is set to 240 μm2/mm regardless of the plate thickness in addition to the configuration in the above-described item (5).
(7) The aspect of the present invention is the method of producing the liquid crystal panel, in which in the abutment area determination step, the approximate curve is set in a strip shape having a width of ±20 μm2/mm2 in addition to the configuration in any one of the above-described items (1) to (6).
(8) The aspect of the present invention is the method of producing the liquid crystal panel, in which in the abutment area determination step, the approximate curve includes a plurality of approximate curves prepared for each of a plurality of maximum environmental temperatures assumed in a use environment of the liquid crystal panel, and the abutment area is determined depending on the maximum environmental temperature in addition to the plate thickness within a range sandwiched between the one approximate curve selected from among the plurality of approximate curves and the straight line in addition to the configuration in any one of the above-described items (1) to (7).
(9) The aspect of the present invention is the method of producing the liquid crystal panel, further including a slimming step for polishing a plate surface opposite to a plate surface on the side of the liquid crystal layer in the pair of substrates to slim the pair of substrates in addition to the configuration in any one of the above-described items (1) to (8).
(10) The aspect of the present invention is the method of producing the liquid crystal panel, in which the spacer is selectively formed on one of the pair of substrates in the spacer formation step, and the spacer is made to abut on the other substrate when the paired substrates are bonded to each other in the bonding step in addition to the configuration described in any one of the above-described items (1) to (9).
(11) The aspect of the present invention is the method of producing the liquid crystal panel, in which a first spacer constituent section constituting the spacer is formed on one of the pair of substrates while a second spacer constituent section constituting the spacer is formed on the other substrate in the spacer formation step, and the first spacer constituent section and the second spacer constituent section are made to abut on each other when the paired substrates are bonded to each other in the bonding step in addition to the configuration described in any one of the above-described items (1) to (9).
According to the present invention, it can be made difficult for a display failure to occur even if the plate thickness of a substrate is diverse.
A first embodiment of the present invention will be described with reference to
The liquid crystal panel 10 is provided with a seal section 11 interposed between respective outer peripheral ends of the pair of substrates 10A and 10B in a form surrounding the liquid crystal layer 10C and a spacer 12 disposed nearer to the center than the seal section 11 and interposed between respective central portions of the pair of substrates 10A and 10B. The seal section 11 is composed of a ultraviolet curable resin material or a thermosetting resin material, for example, and has a frame shape to seal the liquid crystal layer 10C sandwiched between the pair of substrates 10A and 10B. The spacer 12 is provided on the CF substrate 10A out of the pair of substrates 10A and 10B. The spacer 12 is formed in a substantially columnar shape protruding toward the array substrate 10B while penetrating the liquid crystal layer 10C from the CF substrate 10A, and holds a distance D between the pair of substrates 10A and 10B, i.e., a thickness (a cell gap) of the liquid crystal layer 10C by its protruding distal end surface abutting on an inner surface of the array substrate 10B. The thickness of the liquid crystal layer 10C held by the spacer 12 is preferably approximately 2 μm to 5 μm, but not necessarily limited to this. The spacer 12 is composed of a resin material having a light transmission property, for example, and is formed within a plate surface of the CF substrate 10A by a known photolithography method, like another structure, when the CF substrate 10A is produced. The spacer 12 easily disturbs an orientation of a liquid crystal material in the vicinity of itself, although it has alight transmission property. Accordingly, the spacer 12 is preferably disposed to overlap the light shielding portion and a wiring (a light shielding structure) on the side of the array substrate 10B, but not necessarily limited to this. The spacer 12 is preferably regularly arranged within the plate surface of the CF substrate 10A, but not necessarily limited to this.
The liquid crystal panel 10 is configured as described above. Then, an outline of a method of producing the liquid crystal panel 10 will be described with reference to
In the seal section forming process, the seal section 11 is formed to be drawn in a frame shape using a dispenser device or the like for the outer peripheral end on an inner surface of the CF substrate 10A, as illustrated in
The above-described slimming process is useful when the liquid crystal panel 10 is thinned, but a production cost increases. Therefore, if reduction in the production cost is given priority over the thinning of the liquid crystal panel 10, the slimming process may not be performed. Thus, in recent years, when the liquid crystal panel 10 is produced, the slimming process may or may not be performed. Further, a target plate thickness BT may also tend to be diversified in the slimming process. When the plate thickness BT of the pair of substrates 10A and 10B constituting the liquid crystal panel 10 is diversified, the following problem may occur. That is, if the number of spacers 12 to be installed, for example, is made constant regardless of the plate thickness BT of the pair of substrates 10A and 10B being diversified, when the produced liquid crystal panel 10 is left in a leaned state for a predetermined time period such that its long side direction (X-axis direction) is along a vertical direction, the liquid crystal material may be accumulated on the lower end side of the liquid crystal panel 10 by gravity. More specifically, if the number of spacers 12 to be installed, for example, is constant and the plate thickness BT of the pair of substrates 10A and 10B is relatively small, the pair of substrates 10A and 10B is relatively easily deformed. Accordingly, when a filling amount of the liquid crystal material is rather excessive and when the liquid crystal material thermally expands under a high temperature environment, respective central portions in the long side direction of the pair of substrates 10A and 10B are deformed to expand, as illustrated in
As a result of earnest examination, the inventors of the present application have found that the above-described liquid crystal accumulation problem does not occur depending on only the plate thickness BT of the pair of substrates 10A and 10B but the distance D between the pair of substrates 10A and 10B and design of the spacer 12 that holds the distance D are associated therewith. A specific content of the examination will be described below.
First, respective pluralities of two types of liquid crystal panels 10, which differ in a plate thickness BT of a pair of substrates 10A and 10B, for which a distance D between the pair of substrates 10A and 10B (a thickness of a liquid crystal layer 10C) and a protrusion height (height) T of a spacer 12 were changed, were produced, to perform a comparative experiment 1 for inspecting whether or not a failure occurs in each of the liquid crystal panels 10. The distance D between the pair of substrates 10A and 10B depends on a filling amount of a liquid crystal material composing the liquid crystal layer 10C. Inspection of the liquid crystal panel 10 in the experiment includes high-temperature inspection and low-temperature inspection, illustrated below. In the high-temperature inspection, an inspector visually observed the liquid crystal panel 10 via a polarizing plate for inspection after the liquid crystal panel 10 was left in a leaned state for 12 hours in a temperature environment of 85° C., to judge the presence or absence of unevenness. In the low-temperature inspection, the inspector visually observed the liquid crystal panel 10 via the polarizing plate for inspection after the liquid crystal panel 10 was left in a leaned state for 12 hours in a temperature environment of −40° C., to judge the presence or absence of a bubble. An experimental result of the experiment is as illustrated in
The experimental result of the comparative experiment 1 will be described. Both
Then, respective pluralities of two types of liquid crystal panels 10, which differ in a plate thickness BT of a pair of substrates 10A and 10B, for which a difference (D−T) obtained by subtracting a protrusion height T of a spacer 12 from a distance D between the pair of substrates 10A and 10B and a substantial abutment area S per unit area of the spacer 12 on the array substrate 10B were changed, were produced, to perform a comparative example 2 for performing similar inspection to that in the above-described comparative experiment 1. In the comparative experiment 2, a range R related to a preferable numerical range of the difference (D−T) is obtained based on the inspection while a relationship between the range R and an upper-limit value of the above-described abutment area S related to the spacer 12 is plotted on a graph illustrated in
An experimental result of the comparative experiment 2 will be described.
Then, for the graph (
An experimental result of the comparative experiment 3 will be described.
Then, a plurality of liquid crystal panels 10 that differ in the above-described abutment area S related to the spacer 12 were produced, to perform a comparative experiment 4 for applying pressure (an external force) from outside to the liquid crystal panels 10. In the comparative experiment 4, the pressure to be applied from outside to each of the liquid crystal panels 10 that differ in the abutment area S was gradually increased, and pressure immediately before leading to a state where a distance D between a pair of substrates 10A and 10B cannot be held because the spacer 12 included in each of the liquid crystal panels 10 is plastically deformed was measured as a pressure limit F. A result of the measurement is illustrated in
The experimental result of the comparative experiment 4 will be described.
Based on examination of the comparative experiment 1 to the comparative experiment 4 described above, an abutment area determination process for determining the substantial abutment area S per unit area of the spacer 12 on the array substrate 10B depending on the plate thickness BT of the pair of substrates 10A and 10B is performed prior to a spacer formation process included in a CF substrate production process in the method of producing the liquid crystal panel 10. In the abutment area determination process, the abutment area S is determined, within a range sandwiched between an approximate curve obtained by plotting, when the difference (D−T) between the protrusion height T of the spacer 12 and the distance D between the pair of substrates 10A and 10B is set as a reference value, an upper-limit value of the abutment area S for each of the plate thicknesses BT and a straight line on which the abutment area S is set to 230 μm2/mm2 regardless of the plate thickness BT, depending on the plate thickness BT, as illustrated in
More specifically, in the abutment area determination process according to the present embodiment, a minimum value and a maximum value related to the difference (D−T) between the protrusion height T of the spacer 12 and the distance D between the pair of substrates 10A and 10B are found based on the comparative experiment 1, and a range R between the minimum value and the maximum value is set as a reference value. The difference (D−T) between the distance D between the pair of substrates 10A and 10B and the protrusion height T of the spacer 12 is preferably set to a value between a maximum value at which the above-described liquid crystal accumulation problem can be solved and a minimum value at which the above-described low-temperature bubble problem can be solved. In the abutment area determination process, the range R between the minimum value and the maximum value related to the above-described difference (D−T) is set as the reference value. Accordingly, both the above-described liquid crystal accumulation problem and the above-described low-temperature bubble problem are made difficult to create. In the abutment area determination process according to the present embodiment, the reference value is set in a range from 0.13 μm to 0.17 μm, and the reference value is set to 0.15 μm from within the range. Thus, both the above-described liquid crystal accumulation problem and the above-described low-temperature bubble problem are made more difficult to create.
In the abutment area determination process according to the present embodiment, the abutment area S is preferably determined depending on the plate thickness BT of the pair of substrates 10A and 10B within the range sandwiched between the above-described approximate curve and the straight line on which the abutment area S is set to 234 μm2/mm2 regardless of the plate thickness BT. Thus, the spacer 12 is not easily plastically deformed due to the external force to be exerted on the pair of substrates 10A and 10B from the production apparatus or the like in the production processes, which is favorable in improving yield. Further, in the abutment area determination process, the abutment area S is more preferably determined depending on the plate thickness BT of the pair of substrates 10A and 10B within the range sandwiched between the above-described approximate curve and the straight line on which the abutment area S is set to 240 μm2/m2 regardless of the plate thickness BT. Thus, even when an unexpectedly large outer force is suddenly exerted on the pair of substrates 10A and 10B from the production apparatus or the like in the production processes, a reliability with which the plastic deformation of the spacer 12 is prevented becomes high, which is more favorable in improving yield.
As described above, the method of producing the liquid crystal panel 10 according to the present embodiment includes an abutment area determination process for determining, within a range sandwiched between an approximate curve obtained by plotting, when a difference (D−T) between a protrusion height (height) T of a spacer 12 that is interposed between a pair of substrates 10A and 10B with a liquid crystal layer 10C interposed therebetween and holds a distance D between the pair of substrates 10A and 10B by abutting on the array substrate 10B as its counterpart and the distance D is set as a reference value, an upper-limit value of a substantial abutment area S per unit area on the array substrate 10B as the counterpart for each of a plurality of plate thicknesses BT of the pair of substrates 10A and 10B that differ from one another and a straight line on which the abutment area S is set to 230 μm2/mm2 regardless of the plate thickness BT, the abutment area S depending on the plate thickness BT, a spacer formation process for forming the spacer 12 to have the abutment area S determined in the abutment area determination process, and a bonding process for bonding the pair of substrates 10A and 10B to each other.
First, the spacer 12 formed to be interposed between the pair of substrates 10A and 10B with the liquid crystal layer 10C sandwiched therebetween is made to abut on the array substrate 10B as the counterpart, to hold the distance D between the pair of substrates 10A and 10B, i.e., the thickness of the liquid crystal layer 10C. The distance D between the pair of substrates 10A and 10B can vary depending on a filling amount of a liquid crystal material composing the liquid crystal layer 10C. When the filling amount of the liquid crystal material becomes excessive and the above-described distance D becomes excessively larger than the protrusion height T of the spacer 12, the liquid crystal material is accumulated on the lower end side of the produced liquid crystal panel 10 by gravity when the liquid crystal panel 10 is leaned so that a display failure may occur. Conversely, when the filling amount of the liquid crystal material is insufficient and the above-described distance D becomes excessively smaller than the protrusion height T of the spacer 12, a bubble may occur due to the liquid crystal material thermally contracting under a low-temperature environment. On the other hand, if the difference (D−T) between the distance D between the pair of substrates 10A and 10B and the protrusion height T of the spacer 12 is appropriately set, both the above-described liquid crystal accumulation problem and the above-described low-temperature bubble problem can be made difficult to create. A value of the difference (D−T) is the above-described “reference value”.
On the other hand, the substantial abutment area S per unit area on the array substrate 10B as the counterpart of the spacer 12 is calculated, when the spacer 12 includes a plurality of spaces 12 to be installed, for example, by multiplying the substantial unit abutment area on the array substrate 10B as a counterpart of each of the spacers 12 by the number of the spacers 12 to be installed per unit area. When the abutment area S related to the spacer 12 becomes excessively large, the pair of substrates 10A and 10B is rigidly supported by the spacer 12 so that the pair of substrates 10A and 10B is not easily deformed. Accordingly, the above-described liquid crystal accumulation problem may occur. Conversely, if the above-described abutment area S related to the spacer 12 becomes excessively small, there may occur a problem that the spacer 12 cannot resist an external force when the external force is exerted on the produced liquid crystal panel 10 but is plastically deformed. Further, the larger the plate thickness BT of the pair of substrates 10A and 10B is, the less easily the pair of substrates 10A and 10B is deformed depending on a variation in the filling amount of the liquid crystal material composing the liquid crystal layer 10C. Accordingly, the liquid crystal accumulation problem tends to easily occur. Therefore, an appropriate value of the above-described abutment area S related to the spacer 12 can vary depending on the plate thickness BT of the pair of substrates 10A and 10B.
In view of these circumstances, in producing the liquid crystal panel 10, the abutment area determination process for determining the abutment area S related to the spacer 12 depending on the plate thickness BT of the pair of substrates 10A and 10B is performed prior to the spacer formation processing being performed. More specifically, in the abutment area determination process, the approximate curve is obtained by setting the reference value related to the difference (D−T) between the protrusion height T of the spacer 12 and the distance D between the pair of substrates 10A and 10B and plotting the upper-limit value of the above-described abutment area S related to the spacer 12 in the reference value for each of the plurality of plate thicknesses BT. The approximate curve suggests a tendency that the smaller the plate thickness BT of the pair of substrates 10A and 10B becomes, the larger the upper-limit value of the above-described abutment area S related to the spacer 12 tends to be while the larger the plate thickness BT of the pair of substrates 10A and 10B becomes, the smaller the upper-limit value of the above-described abutment area S related to the spacer 12 tends to be. This is conceived to reflect that the liquid crystal accumulation problem does not easily occur even if the above-described abutment area S related to the spacer 12 is large to some degree because the substrates 10A and 10B are easily deformed depending on a variation in the filling amount of the liquid crystal material composing the liquid crystal layer 10C if the plate thickness BT of the pair of substrates 10A and 10B is small. Conversely, this is conceived to reflect a situation where the liquid crystal accumulation problem occurs unless the above-described abutment area S related to the spacer 12 is made sufficiently small because the substrates 10A and 10B are not easily deformed depending on the variation in the filling amount of the liquid crystal material composing the liquid crystal layer 10C if the plate thickness BT of the pair of substrates 10A and 10B is large.
In the abutment area determination process, the above-described abutment area S related to the spacer 12 is determined depending on the plate thickness BT of the pair of substrates 10A and 10B within the range sandwiched between the above-described approximate curve and the straight line on which the abutment area S related to the spacer 12 is set to 230 μm2/mm2 regardless of the plate thickness BT of the pair of substrates 10A and 10B. When the above-described abutment area S related to the spacer 12 is set to 230 μm2/mm2 or more regardless of the plate thickness BT of the pair of substrates 10A and 10B, a situation where the spacer 12 is plastically deformed can be avoided even if the external force to be exerted on the produced liquid crystal panel 10 reaches 0.1 Kgf/mm2. The value “0.1 Kgf/mm2” corresponds to an assumed maximum value of a force produced when a user presses the liquid crystal panel 10 with his/her finger, for example, when the produced liquid crystal panel 10 is used. Therefore, when the above-described abutment area S related to the spacer 12 is determined to be within the above-described range, all the above-described liquid crystal accumulation problem, the above-described low temperature bubble problem, and the problem that the spacer 12 is plastically deformed can be made difficult to create even if the plate thickness BT of the pair of substrates 10A and 10B constituting the liquid crystal panel 10 to be produced has any value. Then, in the spacer formation process, the spacer 12 is formed to have the abutment area S determined in the abutment area determination process. In the bonding process, when the CF substrate 10A and the array substrate 10B are bonded to each other, the liquid crystal panel 10 in which the spacer 12 formed to have the abutment area S determined in the abutment area determination process is interposed therebetween.
In the abutment area determination process, the minimum value and the maximum value related to the difference (D−T) are found, and the range R between the minimum value and the maximum value is set as the reference value. The difference (D−T) between the distance D between the pair of substrates 10A and 10B and the protrusion height T of the spacer 12 is preferably set to a value between a maximum value at which the above-described liquid crystal accumulation problem can be solved and a minimum value at which the above-described low-temperature bubble problem can be solved. In the abutment area determination process, the range R between the minimum value and the maximum value related to the above-described difference (D−T) is set as the reference value. Accordingly, both the above-described liquid crystal accumulation problem and the above-described low-temperature bubble problem are made difficult to create.
In the abutment area determination process, the reference value is set in a range from 0.13 μm to 0.17 μm. Thus, both the above-described liquid crystal accumulation problem and the above-described low-temperature bubble problem are made more difficult to create.
In the abutment area determination process, the reference value is set to 0.15 μm. Thus, both the above-described liquid crystal accumulation problem and the above-described low-temperature bubble problem are made much more difficult to create.
In the abutment area determination process, the abutment area S is determined depending on the plate thickness BT within the range sandwiched between the approximate curve and the straight line on which the abutment area S is set to 234 μm2/mm2 regardless of the plate thickness BT. As a result, the situation where the spacer 12 is plastically deformed can be avoided even if the external force to be exerted on the produced liquid crystal panel 10 reaches 1.5 Kgf/mm2. The value “0.5 Kgf/mm2” corresponds to the assumed maximum value of the external force to be exerted on the pair of substrates 10A and 10B from the production apparatus or the like in the processes for producing the liquid crystal panel 10. Therefore, when the above-described abutment area S related to the spacer 12 is determined to be within the above-described range, the spacer 12 is not easily plastically deformed due to the external force to be exerted on the pair of substrates 10A and 10B from the production apparatus or the like in the production processes, which is favorable in improving yield.
In the abutment area determination process, the abutment area S is determined depending on the plate thickness BT within the range sandwiched between the approximate curve and the straight line on which the abutment area S is set to 240 μm2/mm2 regardless of the plate thickness BT. As a result, the situation where the spacer 12 is plastically deformed can be avoided even if the external force to be exerted on the produced liquid crystal panel 10 reaches 1.5 Kgf/mm2. The value “1.5 Kgf/mm2” corresponds to three times the assumed maximum value of the external force to be exerted on the pair of substrates 10A and 10B from the production apparatus or the like in the processes for producing the liquid crystal panel 10. Therefore, when the above-described abutment area S related to the spacer 12 is determined to be within the above-described range, a reliability with which the spacer 12 is prevented from being plastically deformed becomes high even if the unexpectedly large external force has been suddenly exerted on the pair of substrates 10A and 10B from the production apparatus or the like in the production processes, which is more favorable in improving yield.
In the abutment area determination process, the approximate curve is set in a strip shape having a width of +20 μm2/mm2. The width of ±20 μm2/mm2 with respect to a central value in the strip-shaped approximate curve is an error that can occur in the upper-limit value of the abutment area S to be plotted for each of the plate thicknesses BT of the pair of substrates 10A and 10B, and the more appropriate abutment area S can be determined based on the approximate curve considering the error.
The method of producing the liquid crystal panel 10 includes a slimming process for polishing a plate surface opposite to a plate surface on the side of the liquid crystal layer 10C in the pair of substrates 10A and 10B and slimming the pair of substrates 10A and 10B. As a result, in the slimming process, the pair of substrates 10A and 10B is slimmed to have a predetermined plate thickness BT. When the pair of substrates 10A and 10B is slimmed, the plate thickness BT of the pair of substrates 10A and 10B becomes diverse. Accordingly, the above-described liquid crystal accumulation problem or the like easily occurs depending on the filling amount of the liquid crystal material. In this respect, in the abutment area determination process, the abutment area S related to the spacer 12 within the range between the approximate curve and the straight line is determined depending on the plate thickness BT to be a purpose in the slimming process. Accordingly, even if the plate thickness BT of the pair of substrates 10A and 10B is diverse, the above-described liquid crystal accumulation problem or the like can be made difficult to create.
The spacer 12 is selectively formed on the CF substrate (the one substrate) 10A in the pair of substrates 10A and 10B in the spacer formation process, and the spacer 12 is made to abut on the array substrate (the other substrate) 10B when the paired substrates 10A and 10B are bonded to each other in the bonding process. As a result, the area of the protruding distal end surface of the spacer 12 matches the substantial unit abutment area of the spacer 12 on the array substrate 10B. Therefore, the substantial abutment area S per unit area on the array substrate 10B can be easily calculated.
A second embodiment of the present invention will be described with reference to
In the abutment area determination process according to the present embodiment, a plurality of approximate curves are prepared for each of a plurality of maximum environmental temperatures MT assumed in a use environment of a liquid crystal panel, and an abutment area S is determined depending on the maximum environmental temperature MT in addition to a plate thickness BT within a range sandwiched between the one approximate curve selected from among the plurality of approximate curves and a straight line. The liquid crystal panel also varies in the maximum environmental temperature MT to be assumed when used in different environments. For example, the maximum environment temperature MT to be assumed in an in-vehicle liquid crystal panel tends to be higher than the maximum environmental temperature MT to be assumed in an in-room stationary liquid crystal panel. The liquid crystal panels which differ in the maximum environmental temperature MT to be thus assumed differ in a thermal expansion amount of a liquid crystal material composing a liquid crystal layer, for example. Accordingly, the liquid crystal panels may also differ in an upper-limit value of an abutment area S related to a spacer due to the difference. Examination performed for an effect of the maximum environmental temperature MT will be described below.
First, respective pluralities of two types of liquid crystal panels, which differ in a maximum environmental temperature MT, for which a difference (D−T) obtained by subtracting a protrusion height T of a spacer from a distance D between a pair of substrates and a substantial abutment area S per unit area of the spacer on an array substrate were changed, were produced, to perform a comparative experiment 5 for performing similar inspection to that in the above-described comparative experiment 1 described in the first embodiment. In the comparative experiment 5, a range R related to a preferable numerical range of the difference (D−T) is obtained based on the inspection while a relationship between the range R and an upper-limit value of the above-described abutment area S related to the spacer is plotted on a graph illustrated in
An experimental result of the comparative experiment 5 will be described.
Then, in a comparative experiment 6, a graph on which an upper-limit value of the above-described abutment area S related to the spacer in a case where the range R is set as a reference value (0.15 μm) in the graph (
An experimental result of the comparative experiment 6 will be described.
Then, for the above-described comparative experiment 6, a value of the abutment area S related to the spacer is acquired for each 5° C. until the maximum environmental temperature MT reaches 120° C. from 30° C. Moreover, in a comparative experiment 7, a relationship between a maximum environmental temperature MT and an environmental coefficient EF of an abutment area S related to a spacer with a case where the maximum environmental temperature MT is 85° C. as a reference is plotted on a graph illustrated in
Then, in a comparative experiment 8, a plurality of approximate curves that differ in a maximum environmental temperature MT were acquired by multiplying the numerical value of the abutment area S related to the approximate curve illustrated in
An experimental result of the comparative experiment 8 will be described. According to
Based on examination of the comparative experiment 1 to the comparative experiment 4 described above, in the abutment area determination process according to the present embodiment, a plurality of approximate curves are prepared for each of a plurality of maximum environmental temperatures MT to be assumed in a use environment of a liquid crystal panel, and an abutment area S is determined depending on the maximum environmental temperature MT in addition to a plate thickness BT within a range sandwiched between the one approximate curve selected from among the plurality of approximate curves and a straight line, as illustrated in
As described above, according to the present embodiment, in the abutment area determination process, the plurality of approximate curves are prepared for each of the plurality of maximum environmental temperatures MT to be assumed in the use temperature of the liquid crystal panel, and the abutment area S is determined depending on the maximum environmental temperature MT in addition to the plate thickness BT within the range sandwiched between the one approximate curve selected from among the plurality of approximate curves and the straight line. The liquid crystal material composing the liquid crystal layer has a property that its viscosity changes depending on an environmental temperature, and the above-described liquid crystal accumulation problem may easily occur particularly when the viscosity decreases under the high-temperature environment. Therefore, the upper-limit value of the above-described abutment area S related to the spacer needs to be made lower when the maximum environmental temperature MT to be assumed in the use environment of the liquid crystal panel is high than when the maximum environmental temperature MT is low. In view of these circumstances, in the abutment area determination process, a plurality of approximate curves, described above, are prepared for each of the plurality of maximum environmental temperatures MT to be assumed in the use environment of the liquid crystal panel, the one approximate curve is selected from among the plurality of approximate curves depending on the maximum environmental temperature of interest, and the above-described abutment area S associated with the spacer is determined depending on the plate thickness BT of the pair of substrates within the range sandwiched between the selected approximate curve and the above-described straight line. As a result, if the maximum environmental temperature MT is high, the upper-limit value within the above-described range is kept low. Accordingly, when the spacer is formed in the spacer formation process based on the abutment area S determined in the abutment area determination process, the liquid crystal accumulation problem can be made more reliably difficult to create.
A third embodiment of the present invention will be described with reference to
An outline of a method of producing a liquid crystal panel 210 according to the present embodiment will be described with respect to
In the spacer formation process included in the CF substrate production process, a plurality of first spacer constituent sections 13 are formed in a predetermined distribution within a plane of the CF substrate 210A, as illustrated in
In the method of producing the liquid crystal panel 210 according to the present embodiment, the first spacer constituent section 13 constituting the spacer 212 is formed on the CF substrate (the one substrate) 210A in the pair of substrates 10A and 10B while the second spacer constituent section 14 constituting the spacer 212 is formed on the array substrate (the other substrate) 210B in the spacer formation process, and the first spacer constituent section 13 and the second spacer constituent section 14 are made to abut on each other when the paired substrates 210A and 210B are bonded to each other in the bonding process. As a result, the abutment area of both the respective protruding distal end surfaces of the first spacer constituent section 13 and the second spacer constituent section 14 matches the substantial unit abutment area of the spacer 212 on the array substrate 210B.
The present invention is not limited to the embodiments described by the above-described description and drawings, and embodiments, described below, for example, are included in the technical scope of the present invention.
(1) Although the experimental result of each of the above-described comparative experiments 2 and 3 in the first embodiment illustrates an example of an approximate curve and its function, a specific approximate curve and its function can change depending on various conditions such as a maximum environmental temperature, and are not limited to contents illustrated in the above-described experimental result.
(2) Although in each of the above-described embodiments, a case where the reference value in the range is set to 0.15 μm is illustrated, the reference value in the range can be approximately changed to numerical values other than 0.15 μm. Even in the case, although the reference value in the range is preferably selected from within a range of 0.13 μm to 0.17 μm, the present invention is not necessarily limited to this.
(3) Although a case where a lower-limit value in the range as the reference in determining the abutment area related to the spacer in the abutment area determination process is set to 230 μm2/mm2, 234 μm2/mm2, or 240 μm2/mm2 has been illustrated in each of the above-described embodiments, a specific numerical value of the above-described lower-limit value can also be set to values other than the numerical values as long as it is larger than 230 μm2/mm2.
(4) Although in the above-described second embodiment, a case where the four approximate curves that differ in the maximum environmental temperature are prepared has been illustrated, three or less approximate curves that differ in a maximum environmental temperature can also be prepared, or five or more approximate curves that differ in a maximum environmental temperature can also be prepared. A specific numerical value of the maximum environmental temperature can also be appropriately changed.
(5) Although in each of the above-described embodiments, a case where the spacer is formed on the CF substrate has been illustrated, the spacer may be formed on the array substrate. In the case, the array substrate production process includes the spacer formation process.
(6) In addition to the above-described item (5), the spacer may be formed on each of the CF substrate and the array substrate. In the case, the first spacer constituent section formed on the CF substrate and the second spacer constituent section formed on the array substrate are preferably arranged to abut on each other as both the substrates are bonded to each other. At this time, the sum of the protrusion height of the first spacer constituent section and the protrusion height of the second spacer constituent section is a protrusion height of the spacer. In the case, the CF substrate production process and the array substrate production process respectively include spacer formation processes.
(7) Although in each of the above-described embodiments, a case where the one drop fill method is used has been illustrated, a vacuum injection method may be used. In the case, a liquid crystal filling process is added instead of the liquid crystal dropping process after the bonding process.
(8) Although in each of the above-described embodiments, a case where the chemical polishing and slimming processing is performed in the slimming process has been illustrated, slimming processing in a method other than the chemical polishing and slimming processing may be used.
(9) Although in each of the above-described embodiments, a case where the liquid crystal panel having the rectangular shape is disposed such that its long side direction and its short side direction respectively match the X-axis direction and the Y-axis direction in each of the drawings has been illustrated, the liquid crystal panel can also be disposed such that its long side direction and its short side direction respectively match the Y-axis direction and the X-axis direction in each of the drawings. In this case, an axis line in a vertical direction in
This application claims priority from U.S. provisional patent application No. 62/733,247 filed on Sep. 19, 2018. The entire contents of the priority application are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62733247 | Sep 2018 | US |
