JP2021162673A - Dimming unit - Google Patents

Abstract

To provide a dimming unit having a heat radiation structure favorable for eliminating a state of a dimming unit having a large area prone to receive excessive power flow from an FPC(ACF), causing a connection part to heat up.SOLUTION: A dimming unit includes a power supply part of a structure in which an FPC25 for connecting an external power source is bonded to a transparent electrode layer via an ACF. The dimming unit includes heat radiation means 54 configured to discharge heat generated when voltage is applied to the outside, in a vicinity of the FPC at least one transparent electrode layer.SELECTED DRAWING: Figure 6

Description

The present invention relates to a dimming unit including a liquid crystal type dimming sheet and a connecting portion for connecting the dimming sheet to a power source.

The light control sheet includes a light control layer containing a liquid crystal composition and a pair of transparent electrode layers sandwiching the light control layer. When a driving voltage is applied to the pair of transparent electrode layers, the orientation state of the liquid crystal molecules contained in the light control layer changes, so that the light transmittance of the light control sheet changes. (Refer to Patent Document 1) A dimming unit is composed of such a dimming sheet and a connecting portion for connecting a transparent electrode layer to a power source.

When connecting the dimming sheet to an external power source, conventionally, a structure has been adopted in which at least a conductive tape is attached to the exposed surface of the transparent conductive layer and connected to the lead wire via solder formed on the conductive tape. rice field. Nowadays, as a low-cost and simple structure, a structure that draws out wiring by mechanically adhering while electrically connecting using FPC (flexible printed wiring board) and ACF (anisotropic conductive film) is adopted. (See Patent Document 2). In the connection using FPC and ACF, the point-like joining structure by solder on the conductive tape is changed to a planar joining structure, and the durability of the joining is durable against shaking and impact during transportation and installation work of the dimming unit. The sex is improving.

JP-A-2017-187775 Japanese Patent No. 6439029

It has been confirmed that in the connection of the dimming sheet to the external power supply using FPC and ACF, the temperature rise of the connection part is remarkable and the temperature tends to be high compared to the structure in which the light control sheet is connected to the lead wire via solder. There is.

For large-area dimming sheets for applications such as buildings, the drive range to the dimming layer by applying a drive voltage to the FPC is uniformly widened within the sheet, depending on the distance from the power supply position (FPC). It is necessary to apply at a high voltage in order to avoid a voltage drop. Therefore, the fact that an excessive current easily flows into the light control sheet from the FPC (ACF) and the connection portion easily generates heat is more remarkable in the large area light control sheet.

An object of the present invention is to propose a heat dissipation structure suitable for suppressing unnecessary heat generation in an FPC when the entire surface of a transparent electrode layer of a large-area light control sheet is uniformly driven.

The dimming unit according to the present invention
A light control sheet in which a light control layer containing a liquid crystal composition is sandwiched between a first transparent conductive film having a first transparent electrode layer and a second transparent conductive film having a second transparent electrode layer.
In order to apply a voltage from an external power source to the dimming layer, a first and second power feeding unit having FPCs connecting the external power source to the first and second transparent electrode layers, respectively.
It is characterized by having a heat radiating means for releasing heat generated when a voltage is applied to the outside in the vicinity of the FPC in at least one of the transparent electrode layers.

The heat radiating means may be configured to dissipate the heat via a lead-out wiring portion that electrically connects the FPC and the FPC to the external power source.

The FPC has a conductor pattern
The conductor pattern may have a region in which a voltage is applied to the transparent electrode layer and a region in which the heat is transferred.

The ends of the first and second transparent conductive films on which the FPCs of the first and second feeding portions are formed are on the same side of the rectangular film, and the FPCs are separated within the same side without facing each other. It is preferable that the configurations are arranged in such a manner. In this case, the regions where the first and second power feeding portions are formed (hereinafter, referred to as power feeding regions) are concentrated on one side of the rectangular dimming sheet, and the display area of the dimming sheet can be widely and effectively used.

The heat radiating portion of the FPC may be arranged at a location where conductor patterns serving as connection terminals extend in parallel to the outside, and may be joined to the first and second transparent electrode layers by an insulating adhesive. ..

The insulating pressure-sensitive adhesive preferably has high thermal conductivity.

When the entire surface of the transparent electrode layer of the large-area light control sheet is uniformly driven, a heat dissipation structure suitable for suppressing unnecessary heat generation in the FPC in the power feeding unit is provided.

Explanatory drawing which shows the structural outline of the dimming unit. Explanatory drawing which shows the heat generation state in the FPC joint part. Member composition of the power supply part in dealing with by sticking heat dissipation tape. Front view with heat dissipation tape attached. An enlarged cross-sectional view taken along the line AA of FIG. The perspective view which shows the structural example of FPC25. Member configuration of power feeding unit in FPC form 1. The front view of the state where the FPC25 of the first form is joined to the power feeding part. An enlarged cross-sectional view taken along the line BB of FIG. The perspective view which shows the structural example (other example) of FPC25. Member configuration of power feeding unit in FPC form 2. The front view of the state where the FPC25 of the second form is joined to the power feeding part. An enlarged cross-sectional view taken along the line CC of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the drawings are schematic, and for convenience of explanation, the relationship with the plane dimensions, the ratio of the thickness of each layer, and the like may be exaggerated to a size different from the actual scale. Further, the embodiments shown below exemplify a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention describes the materials, shapes, structures, etc. of the constituent parts as follows. It is not specific to anything. The technical idea of the present invention may be modified in various ways within the technical scope specified by the claims stated in the claims.

[Dimming unit]
FIG. 1 is an explanatory diagram showing an outline of the configuration of a dimming unit.

Each component of the dimming unit 100 including the dimming sheet 10 will be described in detail with reference to FIG. In FIG. 1, when it is necessary to distinguish the power feeding unit 20 and the transparent conductive film 15 from each other, one is defined as the first and the other is defined as the second for convenience, and the reference numerals a and b are assigned to each. Display with it.

As shown in the plan view of FIG. 1A, the dimming unit 100 includes a dimming sheet 10 and a power feeding unit 20 (a, b). The dimming sheet 10 is mainly made of a flexible and thin material, and is rich in flexibility. For example, in a large area usage pattern, the dimming unit 100 is used by being sandwiched between two transparent plates such as glass or mounted on the transparent plate. The transparent plate serving as the supporting base material is a transparent plate-shaped member made of glass, resin, or the like, and may be flat or curved. The transparent plate may be, for example, a building material such as a window glass, a partition or a glass wall, or a vehicle member such as an automobile window glass.

In the dimming region (display region), the dimming layer 13 is sandwiched between the first transparent conductive film 15a having the first transparent electrode layer 12 and the second transparent conductive film 15b having the second transparent electrode layer 12. It has been. Specifically, the dimming layer 13 is located between the first transparent electrode layer 12 and the second transparent electrode layer 12 facing each other.

When viewed from the direction facing the surface of the dimming sheet 10, the dimming sheet 10 has a substantially rectangular shape, and a dimming region (display area) occupying most of the dimming sheet 10 and an end portion of the dimming sheet. Includes the power supply area (non-display area) of. The feeding portions 20 (a, b) are formed in the feeding region, and the FPC 25 is connected to the joints 21 provided on the feeding portions 20 (a, b) via the ACF 22. The power feeding region is located at the end of the dimming sheet 10 along one side of the dimming sheet 10. The one side on which the power feeding region is arranged may be any side of a rectangle, and may be set according to the arrangement of the transparent plate and the drive circuit. Further, the power feeding unit 20 (a, b) may be arranged at a position including the central portion of the one side, or as shown in FIG. 1 (a), is arranged at a position including the end portion of the one side. May be good. In the configuration in which the forming portions of the feeding portions 20 (a, b) including the FPC 25 are arranged apart from each other within the same side of the rectangular dimming sheet 10, the feeding regions are concentrated on one side of the dimming sheet 10 and adjusted. The display area of the optical sheet 10 can be widely and effectively used.

1 (b) and 1 (c) are cross-sectional views taken along the lines AA and BB in FIG. 1 (a), respectively. As shown in FIGS. 1B and 1C, the light control sheet includes a light control layer 13, a first transparent conductive film 15a, and a second transparent conductive film 15b. The first transparent conductive film 15a is composed of a first transparent electrode layer 12 and a first transparent film 11 that supports the first transparent electrode layer 12. The second transparent conductive film 15b is composed of a second transparent electrode layer 12 and a second transparent film 11 that supports the second transparent electrode layer 12.

The dimming layer 13 contains a liquid crystal composition. The dimming layer 13 includes, for example, a polymer network type liquid crystal (PNLC: Polymer Network Liquid Crystal), a polymer dispersed liquid crystal (PDLC: Polymer Dispersed Liquid Crystal), a capsule type nematic liquid crystal (NCAP: Nematic Curve Phase), or the like. It is composed. For example, a polymer network type liquid crystal has a polymer network having a three-dimensional network shape, and holds liquid crystal molecules in the voids of the polymer network. The liquid crystal molecules contained in the dimming layer 13 have, for example, positive dielectric anisotropy, and the dielectric constant of the liquid crystal molecules in the long axis direction is larger than the dielectric constant of the liquid crystal molecules in the minor axis direction. The liquid crystal molecules are, for example, Schiff base-based, azo-based, azoxy-based, biphenyl-based, terphenyl-based, benzoic acid ester-based, trans, pyrimidine-based, cyclohexanecarboxylic acid ester-based, phenylcyclohexane-based, and dioxane-based liquid crystal molecules. be.

Each of the first transparent electrode layer 12 and the second transparent electrode layer 12 is a transparent layer having conductivity. Examples of the material constituting the transparent electrode layer 12 include indium tin oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide, zinc oxide, carbon nanotubes (CNT), and poly (3,4-ethylenedioxythiophene). ) (PEDOT)-containing polymer and the like.

Each of the first transparent film 11 and the second transparent film 11 is a transparent base material. As the material of the transparent film 11, a polymer film made of polyethylene, polystyrene, polyethylene terephthalate, polyvinyl alcohol, polycarbonate, polyvinyl chloride, polyimide, polysulfone, cycloolefin polymer, triacetyl cellulose and the like is used.

In the light control sheet in the normal mode, when the driving voltage is not applied to the transparent electrode layer 12, the orientation of the liquid crystal molecules in the long axis direction is irregular. Therefore, the light incident on the dimming layer 13 is scattered, and the dimming region appears cloudy. That is, when the driving voltage is not applied to the dimming layer 13, the dimming region is opaque. On the other hand, when a driving voltage is applied between the first transparent electrode layer 12 and the second transparent electrode layer 12 through the FPC 25, the liquid crystal molecules are oriented, and the long axis direction of the liquid crystal molecules is between the transparent electrode layers 12 and 12. The orientation is along the direction of the electric field. As a result, light is easily transmitted through the dimming layer 13, and the dimming region becomes transparent.

In the light feeding portion 20a (20b), the second transparent conductive film 15b (first transparent conductive film 15a) at the corresponding portion is cut and removed from the light control sheet, and the light control layer 13 is removed by wiping. Area. In the power feeding region, a joint portion 21 serving as an electrical connection terminal is formed on the surface of the first transparent electrode layer 15a (second transparent conductive film 15b) exposed due to the absence of the dimming layer 13, and the FPC 25 is formed on the surface. The ends of the conductor pattern that will be the connection terminals (pads) formed in the above are joined, and the drive power from the external power supply is supplied. ACF22 is arranged at the joining portion of the FPC 25, and is joined to the surface of the first transparent electrode layer 15a (second transparent electrode layer 15b) by thermocompression bonding.

In the FPC 25 arranged in the power feeding region, the conductor pattern serving as the connection terminal (pad portion) is joined to the joining portion (conductive tape) 21 formed on the transparent electrode layer 12 on the feeding region via the ACF 22. A drawer wiring portion that is pulled out of the frame of the dimming sheet 10 is provided, extends from the power feeding region to the outside of the dimming sheet 10, and is connected to a drive circuit (not shown).

The FPC 25 is provided with a wiring layer formed by patterning a metal thin film such as copper on the surface of an insulating resin layer which is a flexible base material made of an insulating resin such as polyimide, and is provided with an external power source. Responsible for supplying power to the dimming sheet from.

ACF22 is a thermosetting or thermoplastic resin sheet material containing surface conductive beads of a fine resin or an inorganic material coated with gold or nickel. This resin sheet material, which may have adhesiveness by itself, is installed between the terminal portion of the FPC 25 and the surface of the transparent electrode layer 12 in the power feeding region, and the resin is cured or molded while being heat-bonded. As a result, the surface conductive beads are arranged in contact with each other in the thickness direction of the pattern, which is the heat-bonded portion, so that conduction can be obtained. On the other hand, in the in-plane direction of the ACF 22 without heat crimping (direction perpendicular to the thickness direction), conduction due to contact of the surface conductive beads does not occur, and the ACF 22 is conductive in the thickness direction and the in-plane direction. Has anisotropy.

As shown in FIG. 2, the problem to be solved in the present invention, which is set as "heat generation at the connection portion", is a location where the connection terminals (pad portions) of the FPC 25 are arranged diagonally upward (outside the arrangement in the left-right direction and the up-down direction). It has been confirmed that there is a high tendency to concentrate on the heat generating portion 30).

Therefore, a heat radiating tape 40 made of a material having high heat dissipation (at least one of the adhesive 42 laminated with the base material 41) is attached to the power feeding unit 20 (a, b) so as to cover the FPC 25 and ACF 22. It is also possible to deal with it by matching methods. FIG. 3 is a member configuration of the power feeding unit in the above-mentioned countermeasure, and FIG. 4 is a front view of a state in which the heat radiating tape 40 is attached.

FIG. 5 is an enlarged cross-sectional view taken along the line AA of FIG. The thickness of the dimming sheet 10 and the unevenness of the surface increase by the amount of the heat radiating tape 40 that covers the FPC 25 with the power feeding unit 20a, and the effect is increased by the amount of the heat radiating tape 40 of the power feeding unit 20b (not shown). become.

When applied to the dimming unit 100 in which the dimming sheet 10 is sandwiched between two transparent plates such as glass or mounted on the transparent plate, a local increase in thickness and an increase in surface irregularities are disadvantageous. , Improvements and corrections are required.

In the present embodiment, a configuration in which the FPC 25 is provided with a heat radiating portion is presented instead of a heat radiating member that is separate from the FPC 25.

<FPC form 1>
FIG. 6 is a perspective view showing a structural example of the FPC 25. The end of the lead-out wiring portion formed by patterning a conductive metal layer such as copper foil formed on a base film such as polyimide is a parallel portion of the connection terminal (pad portion) 53.

Since the heat generating portion 30 tends to be concentrated diagonally above the parallel portion of the connection terminal (pad portion) 53 (see FIG. 2), the portion where the connection terminal (pad portion) 53 extends in an arm shape to the outside in parallel. The heat radiating portion 54 is formed in the above.

In the figure, arms 55 are formed on both sides of connection terminals (pad portions) 53 arranged in parallel in the left-right direction, and a conductive metal layer serving as a heat dissipation portion 54 is exposed from the coating layer, and is "T-shaped". Although the FPC 25 of the above is deformed into a "Y-shape", the arm 55 and the heat radiating portion 54 may have at least one shape.

FIG. 7 is a member configuration of the power feeding portion in the first embodiment, and FIG. 8 is a front view of the FPC 25 of the first embodiment joined to the feeding portion. The connection terminal (pad portion) 53 at the end of the lead-out wiring portion formed in the FPC 25 is joined by thermocompression bonding via the ACF 22, and the heat radiating portion 54 formed at the tip of the arm 55 is formed by the insulating adhesive 23. Be joined. The pressure-sensitive adhesive 23 preferably has good heat dissipation as well as insulating properties. Among various products such as siloxane-free, no concern about contact failure, elastic adhesive with high thermal conductivity, and adhesive with excellent electrical insulation because it uses non-conductive inorganic filler, EW2070 (made by 3M) Thermally conductive epoxy adhesive), TB2955 (manufactured by Three Bond), DM6030HK (manufactured by Daimat), CF3350 (manufactured by Emerson & Cumming), Sircon (R) GR (manufactured by Fuji Polymer Industry), AD-7002 (manufactured by Toshimasa Kogyo), Examples thereof include TC-50TXS (manufactured by Shinetsu Silicone) and DA6523 (manufactured by Toray Dow Corning).

FIG. 9 is an enlarged cross-sectional view taken along the line BB of FIG. The heat radiating portion 54 formed at the tip of the lead wire of the FPC 25 joined by the power feeding portion 20a absorbs the heat of the heat generating portion 30, and the adhesive 23 → FPC 25 (the solder pad portion 56 formed at the other end of the lead wire). ) → Solder 26 → Lead wire 27 heat is transferred in this order, and the heat generated in the power feeding unit 20a is dissipated.

<FPC form 2>
FIG. 10 is a perspective view showing a structural example (another example) of the FPC 25. The end of the lead-out wiring portion formed by patterning a conductive metal layer such as copper foil formed on a base film such as polyimide is a parallel portion of the connection terminal (pad portion) 53.

In the second embodiment, in the first embodiment, the arms 55 formed on both sides of the connection terminal (pad portion) 53 arranged in parallel in the left-right direction extend so as to wrap around the tip of the connection terminal (pad portion) 53, and the heat dissipation portion 54 is connected. The structure is formed so as to widely surround the joint portion of the terminal (pad portion) 53. As shown in the figure, it exists in a rectangular area including the connection terminal (pad part) 53 and the heat radiating part 54, and although it does not have a shape extending as an "arm", the area including the heat radiating part 54 is convenient. Is referred to as an arm 55. In the second form, it is not necessary to specify the outer shape (arm 55) of the FPC 25 by cutting, and it is produced by changing the patterning of the conductive metal layer such as copper foil formed on the base film. As the size of the heat radiating unit 54 increases, the heat radiating function is further improved.

FIG. 11 is a member configuration of the power feeding portion in the second form, and FIG. 12 is a front view of the state in which the FPC 25 of the first form is joined to the feeding portion. The connection terminal (pad portion) 53 at the end of the lead-out wiring portion formed in the FPC 25 is joined by thermocompression bonding via the ACF 22, and the heat radiating portion 54 formed at the tip of the arm 55 is formed by the insulating adhesive 23. Be joined. The pressure-sensitive adhesive 23 is common to Form 1.

FIG. 13 is an enlarged cross-sectional view taken along the line CC of FIG. The heat radiating portion 54 formed at the tip of the lead wire of the FPC 25 joined by the power feeding portion 20a absorbs the heat of the heat generating portion 30, and the adhesive 23 → FPC 25 (the solder pad portion 56 formed at the other end of the lead wire). ) → Solder 26 → Lead wire 27 heat is transferred in this order, and the heat generated in the power feeding unit 20a is dissipated.

100 ... Dimming unit 10 ... Dimming sheet 15 (a, b) ... Transparent conductive film (1st and 2nd)
11 ... Transparent film (1st and 2nd)
12 ... Transparent electrode layer (first and second)
13 ... Dimming layer 20 (a, b) ... Power feeding unit (first, second)
21 ... Joint (conductive tape)
22 ... ACF
25 ... FPC
53 ... Connection terminal (pad part)
54 ... Heat dissipation part 55 ... Arm 56 ... Solder pad part 26 ... Solder 27 ... Lead wire 40 ... Heat dissipation tape

Claims (6)

A light control sheet in which a light control layer containing a liquid crystal composition is sandwiched between a first transparent conductive film having a first transparent electrode layer and a second transparent conductive film having a second transparent electrode layer.
In order to apply a voltage from an external power source to the dimming layer, a first and second power feeding unit having FPCs connecting the external power source to the first and second transparent electrode layers, respectively.
A dimming unit comprising, in the vicinity of the FPC in at least one of the transparent electrode layers, a heat radiating means for releasing heat generated when a voltage is applied to the outside. The dimming unit according to claim 1, wherein the heat radiating means releases the heat via a lead-out wiring portion that electrically connects the FPC and the FPC to the external power source. The FPC has a conductor pattern
The dimming unit according to claim 1 or 2, wherein the conductor pattern has a region for applying a voltage to the transparent electrode layer and a region for transmitting the heat. The ends of the first and second transparent conductive films on which the FPCs of the first and second feeding portions are formed are on the same side of the rectangular film, and the FPCs are separated within the same side without facing each other. The dimming unit according to any one of claims 1 to 3, wherein the dimming unit is arranged in such a manner. The heat radiating portion of the FPC is arranged at a location where conductor patterns serving as connection terminals extend in parallel to the outside, and is joined to the first and second transparent electrode layers by an insulating adhesive. The dimming unit according to any one of claims 1 to 4. The dimming unit according to claim 5, wherein the insulating pressure-sensitive adhesive has a property of high thermal conductivity.

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