JP6109472B2 - Liquid crystal display device and method of manufacturing liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device including a blue phase liquid crystal as a liquid crystal material, and relates to a liquid crystal display device improved in performance and manufacturing, and a method of manufacturing the liquid crystal display device.

  One of liquid crystal materials used for liquid crystal panels is blue phase liquid crystal. A blue phase liquid crystal is a liquid crystal phase that appears between a chiral nematic phase having a relatively short helical pitch and an isotropic phase. The blue phase liquid crystal can realize a high-speed response as compared with the nematic liquid crystal, and more specifically, has a feature that the response speed is as fast as 10 to 100 μS.

As a conventional technique to which the blue phase liquid crystal is applied, there is a technique for stabilizing the blue phase liquid crystal using a polymer. A manufacturing process of a conventional liquid crystal display device including a blue phase liquid crystal in which the polymer is stabilized is as follows.
Step 1: Add monomer to liquid crystal by adding photopolymerizable monomer to liquid crystal.
Step 2: Control the temperature so that the blue phase liquid crystal appears on the hot plate. (Blue phase needs to be controlled at ± 0.5 ℃)
Step 3: The blue phase is stabilized by irradiating with UV in a state where the blue phase liquid crystal appears and polymerizing.

  Through such a process, a polymer network is formed, in which the blue phase liquid crystal can be oriented. As a result, a liquid crystal display element capable of high-speed driving can be obtained by applying a voltage (see, for example, Patent Document 1).

  FIG. 5 is a diagram showing a panel cross section of a conventional liquid crystal display device including a blue phase liquid crystal as a liquid crystal material. As shown in FIG. 2, a polymer network is formed by UV irradiation between a pixel substrate and a counter substrate facing each other via a spacer, and high-speed driving is realized by a blue phase liquid crystal in the polymer network.

International Publication No. 2005/090520 Pamphlet

However, the prior art has the following problems in putting a liquid crystal display device including a blue phase liquid crystal into practical use.
In the prior art, a photopolymerizable monomer is added to a liquid crystal and polymerized by UV irradiation. However, due to a light shielding layer such as a black matrix, there is a region that is not irradiated with UV light, and unreacted monomers remain. As a result, the retention rate decreases and display unevenness occurs.

  Further, if the in-plane uniformity of UV irradiation or the temperature control for revealing the blue phase liquid crystal is not accurate, the polymer to be formed becomes incomplete and non-uniform in the plane. As a result, initial display unevenness occurs, or display unevenness occurs due to breakage of the polymer network structure when driven for a long time.

  Furthermore, in order to obtain a blue phase liquid crystal, in the previous step 2, temperature control within a range of about 1 degree, which is the appearance range of the blue phase liquid crystal, is necessary, which is a major limitation in the manufacturing process.

Such problems can be roughly classified into performance problems and process problems as follows.
(1) Performance problems-Initial display unevenness, low contrast-Display unevenness due to long-time driving-Retention rate reduction (2) Problems in process-High-accuracy temperature control (± 0.5 degrees) and surface Requires uniform UV irradiation process

  The present invention has been made in order to solve the above-described problems, and solves the performance and process problems that occur when a blue phase liquid crystal is used as a liquid crystal material. And it aims at obtaining the manufacturing method of a liquid crystal display device.

A liquid crystal display device according to the present invention is a liquid crystal display device including a first substrate and a second substrate facing each other, and a liquid crystal sealed between the first substrate and the second substrate, and the liquid crystal display device A liquid crystal material including a blue phase liquid crystal is used, and the micro holes as the small chambers are spatially connected to each other to be three-dimensionally arranged to form one large space, further comprising a microporous structure layer inserted between the second substrate, the blue phase liquid crystal is a Rukoto such as the one state is injected into a large space of microporous structure layer, provided on the microporous structure layer was a state sealed divided into respective micropores, each of fine holes provided in the microporous structure layer, 0.3 [mu] m or more, those which are constituted by a substantially spherical having a diameter of less than 1μm is there.

In addition, the method for manufacturing a liquid crystal display device according to the present invention has a micropore structure in which micropores as individual small chambers are three-dimensionally arranged while being spatially connected to each other to form one large space. A step of attaching a first substrate to one surface of the layer and attaching a second substrate to the other surface opposite to the one surface; and a microporous structure sandwiched between the first substrate and the second substrate A step of sealing the blue phase liquid crystal in each of the micropores provided in the microporous structure layer by injecting the blue phase liquid crystal into one large space of the layer. Each of the micropores is 0 . It is comprised by the substantially spherical shape which has a diameter of 3 micrometers or more and 1 micrometer or less.

  According to the present invention, instead of using a conventional polymer network, a structural layer in which micropores are formed is used, and a monomer is polymerized by filling a gap between the structural layers with a blue phase liquid crystal. By eliminating the need for UV irradiation and temperature control, the problems of performance and process that occur when using blue phase liquid crystal as a liquid crystal material are solved, and more practical liquid crystal display elements and liquid crystal display devices are manufactured. You can get the method.

In Embodiment 1 of this invention, it is a figure which shows the panel cross section of the liquid crystal display device which contains a blue phase liquid crystal as a liquid-crystal material. It is a schematic diagram of the microporous structure film in Embodiment 1 of this invention. It is the flowchart which showed the series of processes regarding manufacture of the liquid crystal display device in Embodiment 1 of this invention. The result of the performance verification test of the liquid crystal display device in Embodiment 1 of this invention is put together. It is a figure which shows the panel cross section of the conventional liquid crystal display device containing a blue phase liquid crystal as a liquid crystal material.

  Hereinafter, preferred embodiments of a liquid crystal display element and a method for producing a liquid crystal display device of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
As described above, in the conventional method using a polymer structure as a stabilization structure (stabilization method) for filling the blue phase liquid crystal, it is necessary to perform UV irradiation and temperature control with high accuracy. On the other hand, the present invention has a technical feature of easily realizing a strong and stable structure while being uniform by using a film in which micropores are formed instead of a polymer structure. .

  FIG. 1 is a diagram showing a panel cross section of a liquid crystal display device including a blue phase liquid crystal as a liquid crystal material in Embodiment 1 of the present invention. The liquid crystal display device according to the first embodiment shown in FIG. 1 includes a blue phase liquid crystal 1, a horizontal electrode 11, a pixel substrate 12, a counter substrate 13, and a microporous structure film 21.

  A fine pore structure film 21 (corresponding to a fine pore structure layer) is provided between the pixel substrate 12 provided with the horizontal electrode 11 on one surface and the counter substrate 13 facing the pixel substrate 12 so as to face the horizontal electrode 11. ) Is sandwiched.

  Here, as the microporous structure film 21, for example, a porous film Propore fabric manufactured by Sumitomo 3M can be used (Microporous Film ProporeFabric http://www.mmm.co.jp/pcrp/microp/index). (See .html)

  The microporous structure film 21 is configured such that micropores as individual small chambers are spatially connected to each other and arranged three-dimensionally while being spatially continuous. That is, each micropore is spatially connected to adjacent micropores, and is connected to each other and arranged three-dimensionally by a film for forming a small chamber, resulting in one continuous large pore. Has a space.

  More specifically, as an example, the distance between the pixel substrate 12 and the counter substrate 13 is about 5 μm, and the microporous structure film 21 sandwiched between them and having an equivalent thickness of about 5 μm has a diameter of 1 μm or less. The micropores having a substantially spherical shape having three are arranged three-dimensionally to form one continuous large space.

  Then, the blue phase liquid crystal can be injected into one large space by filling the blue phase liquid crystal from one place where the microporous structure film 21 exists. As a result, the blue phase is injected into the small chamber in each micropore. The liquid crystal 1 is sealed.

  FIG. 2 is a schematic diagram of the microporous structure film according to Embodiment 1 of the present invention, and schematically shows a state of being divided into small rooms as a panel cross-sectional view. As shown in FIG. 2, the blue phase liquid crystal 1 is sealed and voltage-controlled for each small room provided in the microporous structure film 21, thereby realizing a desired image display.

  Thus, by using the microporous structure film 21, the UV irradiation / temperature control for polymerizing the monomer is unnecessary as in the conventional case, and the manufacturing cost can be reduced.

  Further, the polymer structure of the conventional polymer has a disadvantage that the network structure is easily broken by switching of the liquid crystal when driven for a long time. However, by using a microporous structure instead of a polymer structure, a liquid crystal display device that can maintain a high contrast with stable orientation without the possibility of breaking the microporous structure even when driven for a long time is realized. it can.

  Furthermore, the cell thickness between the pixel substrate 12 and the counter substrate 13 can be easily set to a desired thickness by managing the thickness of the microporous film 21. As a result, it is not necessary to form a spacer used for controlling the cell thickness, and the panel can be enlarged.

  Next, a method for manufacturing a liquid crystal display device and a performance verification experiment in the first embodiment will be described with reference to flowcharts. FIG. 3 is a flowchart showing a series of processes relating to the manufacturing method and performance verification experiment of the liquid crystal display device according to the first embodiment of the present invention. First, in step S301, the pixel substrate 12 provided with the horizontal electrode 11 and the counter substrate 13 are bonded together with the microporous film 21 interposed therebetween.

  Next, in step S302, the blue phase liquid crystal 1 is injected into one large space of the microporous structure film 21 in which the bonding of both substrates is completed, so that the blue phase liquid crystal 1 is filled in each micropore. Next, in step S303, the temperature range of the blue phase liquid crystal 1 is measured using the panel manufactured through steps S301 and S302. The measurement result of the temperature range will be described later in detail with reference to FIG.

  Next, in step S304, a polarizing plate is attached to the panel after the temperature range measurement. In step S305, the contrast is measured based on the state before the voltage is applied (black image display state) and the state after the voltage is applied (white image display state). In addition, display defects are also verified.

  FIG. 4 summarizes the results of the performance verification test of the liquid crystal display device according to Embodiment 1 of the present invention. In collecting this data, three kinds of fine pore structure films 21 having a fine pore diameter of 0.3 μm, 1 μm, and 2 μm are used. In addition, a comparison with a conventional polymer structure is also performed.

  First, with respect to the temperature range, if the diameter of the micropores is 1 μm or less, a temperature range equal to or higher than that of the conventional one can be obtained. In particular, when the diameter of the micropores is 0.3 μm, it is 1.8 times the conventional one. It was found that the temperature range could be covered.

  In addition, good results can be obtained with respect to display defects regardless of the diameter of the fine holes, and white brightness can be obtained as long as the diameter of the fine holes is 1 μm or less. I understood it.

  Furthermore, regarding the contrast, when the diameter of the micropore is 2 μm, the same contrast as the conventional one can be obtained. When the diameter of the micropore is 1 μm, it is about twice, and when the diameter of the micropore is 0.3 μm. It was found that a contrast ratio of about 4 times was obtained. In addition, in any case of the fine hole diameter, a good result was obtained in which the contrast after driving for 24 hours hardly deteriorated from the initial contrast.

  Although not shown in FIG. 4, if the proportion of the space portion formed by each micropore in the micropore structure film 21 is defined as the micropore existence ratio, the diameter of the micropore is in any case. It was proved that when the micropore existence ratio was 95% or more, good luminance was obtained as white luminance.

  As described above, according to the first embodiment, by applying the microporous structure layer, compared with a liquid crystal display device having a conventional polymer structure, cost reduction, high reliability, and large panel size are achieved. It is possible to realize a liquid crystal display device using blue liquid crystal and a method for manufacturing the same, which has an effect of making it possible.

  In addition, from the viewpoint of the temperature range, display failure, and contrast, the micropores provided in the microporous structure film preferably have a diameter of 1 μm or less, and the micropore presence rate is preferably 95% or more by a verification test. Has been demonstrated.

  DESCRIPTION OF SYMBOLS 1 Blue phase liquid crystal, 11 Horizontal electrode, 12 Pixel substrate, 13 Opposite substrate, 21 Micropore structure film (micropore structure layer).

Claims (3)

A first substrate and a second substrate facing each other;
A liquid crystal display device comprising: a liquid crystal sealed between the first substrate and the second substrate,
As the liquid crystal, a liquid crystal material including a blue phase liquid crystal is used,
The micro holes as the small chambers are arranged three-dimensionally while being spatially connected to each other to form one large space, and are inserted between the first substrate and the second substrate. Further comprising a microporous structure layer,
The blue phase liquid crystal, in the one Rukoto such a state of being injected into a large space of the microporous structure layer, sealed divided into each of the fine pore structure wherein provided in the layer micropores State
Each of the said micropore provided in the said micropore structure layer is comprised by the substantially spherical shape which has a diameter of 0.3 micrometer or more and 1 micrometer or less. The liquid crystal display device characterized by the above-mentioned. The liquid crystal display device according to claim 1.
The micropore structure layer has a micropore existence ratio of 95% or more when the ratio of the space portion formed by each micropore to the micropore structure layer is defined as the micropore existence ratio. A liquid crystal display device. The first substrate is attached to one surface of the microporous structure layer in which the micropores as the individual small chambers are spatially connected to each other and are three-dimensionally arranged to form one large space, Affixing a second substrate on the other surface opposite to the one surface;
The micropores provided in the micropore structure layer by injecting a blue phase liquid crystal into the one large space of the micropore structure layer sandwiched between the first substrate and the second substrate. Sealing each of the blue phase liquid crystals,
Each of the said micropore provided in the said micropore structure layer is comprised by the substantially spherical shape which has a diameter of 0.3 micrometer or more and 1 micrometer or less. The manufacturing method of the liquid crystal display device characterized by the above-mentioned.

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