JPH063654A - Dimming film - Google Patents

Abstract

PURPOSE:To improve contrast putting a plurality of dimming film elements one on top of another. CONSTITUTION:A high polymer liquid crystal compound film 3-2 of approximately uniform thickness is kept adjacent to the side of the electrode 2-2 of a transparent conductive film 2, and a common electrode 6 is kept adjacent to the top of the film 3-2. The common electrode 6 is available from the formation of transference electrodes 6-2 and 6-3 via the deposition of ITO(indium-tin oxide film) on both sides of a film (or glass substrate) 6-1. The transference electrode 6-3 of the common electrode 6 is laid on top of the film 3-2 and another high polymer liquid crystal compound film of approximately uniform thickness is kept adjacent to the side of the transference electrode 6-2. In addition, a transparent conductive film 1 at the face opposite the adjacent face of the film 3-1 has a transference electrode 1-2 and the compound film 3-1 adjacent to each other face to face, thereby forming dimming film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light control film using a polymer liquid crystal composite film, and more particularly to a light control film having an improved contrast ratio of light and dark.

[0002]

2. Description of the Related Art Liquid crystals conventionally used for displays and the like have an excellent advantage that they can be driven at a low voltage. However, many of these conventional liquid crystals require a polarizing plate, and as the name implies, they are liquids,
It must be completely sealed to prevent the liquid from leaking.

In comparison with this, the polymer liquid crystal composite film developed in recent years has the advantage that it can be easily deformed into a film shape because it is solid and has plasticity because it has a physical structure in which liquid crystal is wrapped in a polymer. . Further, although the driving voltage is slightly high, it is also an advantage that no polarizing plate is required. FIG. 3 shows an example of a conventional light control film using this type of polymer liquid crystal composite film. The light control film controls the light transmittance with a voltage applied to both sides of the film, and has a function almost equivalent to that of a conventional liquid crystal display arranged between both electrodes. Figure 3
And transparent conductive film (or transparent conductive glass)
1 and 2 are formed as transparent electrodes 1-2 and 2-2 by depositing ITO on one surface of a thin film (or a thin glass having a substantially uniform thickness) 1-1 and 2-1. It
The transparent conductive films 1 and 2 are arranged substantially parallel to each other with their electrode 1-2 and 2-2 surfaces facing each other.
A polymer liquid crystal composite film 3 (having a thickness d) having a substantially uniform thickness is disposed in contact with both electrodes 1-2 and 2-2. The electrode 2-2 is connected to the-terminal of the high frequency power source 4 and is also grounded. The electrode 1-2 is connected to one end of the switch 5, and the other end of the switch 5 is connected to the + terminal of the high frequency power supply 4.
A high-frequency power source 4 is used between the electrodes 1-2 and 2-2 for about 1
A voltage of kHz-60Vpp is applied. The on / off of this voltage application is controlled by the switch 5. When the switch 5 is off, the light transmittance from the top surface 7 to the bottom surface 8 of the light control film and the light transmittance from the bottom surface 8 to the top surface 7 are small, and when the switch 5 is on. , The light transmittance increases.

In this specification, a single light control film having a function equivalent to that of a conventional light control film is called a light control film element.

[0005]

As described above with reference to FIG. 3, in the light control film using the conventional polymer liquid crystal composite film, the voltage applied between the electrodes 1-2 and 2-2 is changed. Although the light transmittance can be controlled by controlling, the ratio of the light transmittance when the voltage is on and the light transmittance when the voltage is off, that is, the contrast cannot be said to be sufficient. For example, if the light control film is made thicker to reduce the light transmittance when the voltage is off, the light transmittance when the voltage is on will also decrease. On the contrary, when the membrane pressure is reduced, the light transmittance is
It goes up with / off. That is, in any case, it is very difficult to improve the contrast. Of course, the contrast can be increased by increasing the drive voltage applied to both electrodes 1-2 and 2-2 of the light control film, but this causes the high frequency power source 4 to be expensive and the size to be large.

An object of the present invention is to provide a light control film of a polymer liquid crystal composite film, which has improved contrast without raising the driving voltage.

[0007]

According to the present invention, a light control film is constructed by stacking a plurality of light control film elements of a polymer liquid crystal composite film having substantially the same characteristics.

[0008]

As described above, in the present invention, a plurality of light control films of polymer liquid crystal composite film having substantially the same characteristics are stacked. Here, the contrast of the conventional light control film and the contrast of the light control film of the present invention are compared when the drive voltage V is constant. However, the light control film of the present invention will be described with reference to FIG. 4, assuming that two light control film elements are stacked. FIG. 4A shows a cross-sectional view of a conventional light control film (abbreviated as film-1), and FIG. 4B shows a light control film (abbreviated as film-2) of the present invention. The incident light quantity is I _0, and the film of FIG.
Let I ₁ be the amount of transmitted light when the voltage from ₁ is on, and turn off the voltage.
Let the amount of transmitted light at that time be I ₁ '. Also, the film of FIG. 4B
Let I ₂ be the amount of transmitted light when the voltage from ₂ is on, and turn off the voltage
The amount of transmitted light when I ₂ 'and also the amount of transmitted light when a voltage off from the first sheet of light control film element (left) I _2' is, the amount of transmitted light when the voltage on is I ₁ Considering this, the following various relationships are established. When the transmittance when the voltage is off the film -1 and _{I 1 '/ I 0 = α} 1, also the transmittance in the voltage on the film-1 and _{I 1 / I 0 = α 2} , the voltage of the film -2 When it is off, the transmittance is I ₂ ′ / I ₀ = (I ₂ ′ / I ₁ ′) × (I ₁ ′ / I ₀ ) = (α ₁ ) ² . Because the transmittance of the first light control film element (left side) and the second light control film element (right side) are equal, I ₂ '/ I ₁ ' = I ₁ '/ I ₀ = α ₁ Is satisfied. Similarly, the transmittance of the film-2 when the voltage is on is I ₂ / I ₀ = (I ₂ / I ₁ ) × (I ₁ / I ₀ ) = (α ₂ ) ² . Because the transmittance of the first light control film element (left side) and the second light control film element (right side) are equal, I ₂ '/ I ₁ ' = I ₁ '/ I ₀ = α ₂ Is satisfied. Table 1 shows a summary of these relationships.

Conventional light control film Light control film of the present invention (Film-1) (Film-2) Drive voltage V V Overall thickness of film d 2 × d Transmittance α ₁ (α ₁ ) ² voltage when voltage is off Transmittance at on time α ₂ (α ₂ ) ² Table 1 Again, Table 1 is briefly described. The driving voltage is V for film-1 and 2 for film-2.
A voltage V is applied to each of the light control film elements. The total thickness of the light control film is d in Film-1.
And the film-2 has a thickness of 2 sheets, which is 2d.
Assuming that the light transmittance of the film-1 when the voltage is off is α ₁ , since the light-modulating film elements having almost the same characteristics and the same thickness are duplicated in the film-2, α ₁ × α ₁ =
(Α ₁ ) ² . Similarly, if the light transmittance of the film-1 when the voltage is on is α ₂ , the film-2 has (α ₂ ) ² .

Therefore, the contrast between film-1 and film-2 is the contrast of film-1 A ₁ = (transmittance when on) / (transmittance when off) = α ₂ / α ₁ contrast A of film-2 ₂ = (transmittance when on) / (transmittance when off) = (α ₂ ) ² / (α ₁ ) ² . That is, film-1 and film ratio of contrast between -2 _{A 2 / A 1 = (α} 2 / α 1) 2 / (α 2 / α 1) = α 2 / α 1> 1 ····· (1) is concluded. This is because the transmittance α ₂ when the voltage is on is larger than the transmittance α ₁ when the voltage is off. Formula (1) means that the contrast of the light control film of the present invention is α ₂ / α ₁ times the contrast of the conventional light control film.

It is apparent that the contrast is further improved by stacking three or more light control film elements in the light control film of the present invention.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows an embodiment of the light control film of the polymer liquid crystal composite film of the present invention. In FIG. 1, parts corresponding to those in FIG. 3 are designated by the same reference numerals. In the light control film of FIG. 1, parts having the same structure and function as those of FIG. 3 will be briefly described to avoid duplication, and only different parts will be described in detail. A polymer liquid crystal composite film having a substantially uniform thickness on the electrode 2-2 side of the transparent conductive film 2 (thickness is d) 3-
2 are contacted with each other, and the upper surface of the composite membrane 3-2 (composite membrane 3-2
The common electrode 6 is brought into contact with the surface 2) which is in contact with the electrode 2-2. Since various configurations can be considered for the common electrode 6, the details will be described later, and here, the film 6 is used.
ITO is vapor-deposited on both sides of the transparent electrode 6-2, 6-3.
Think of what formed. In this embodiment, the transparent electrode 6-3 of the common electrode 6 is formed on the upper surface of the polymer liquid crystal composite film 3-2.
Will be contacted. On the transparent electrode 6-2 side, another polymer liquid crystal composite film having a substantially uniform thickness (thickness is d)
3-1 is contacted with the transparent conductive film 1 on the surface opposite to the contact surface of the composite film 3-1, and the transparent electrode 1-2 and the composite film 3-1 are opposed to each other.

With the light control film thus formed,
The electrodes 1-2 and 2-2 are commonly connected, connected to the negative terminal of the high frequency power source 4, and further grounded. Both electrodes 6-2 and 6-3 formed on both sides of the common electrode 6 are commonly connected and connected to one end of the switch 5. The other end of the switch 5 is connected to the + terminal of the high frequency power supply 4. Between two sets of electrodes,
That is, a voltage of about 1 kHz-60 Vpp is applied between the electrodes 1-2 and 6-2 and between the electrodes 2-2 and 6-3 by using the high frequency power supply 4. The on / off of this voltage application is controlled by the switch 5. When the switch 5 is off, the light transmittance from the top surface 7 to the bottom surface 8 of the light control film and the light transmittance from the bottom surface 8 to the top surface 7 are small, and when the switch 5 is on. , The light transmittance increases. In this embodiment, a positive voltage is applied to the transparent electrodes 6-2 and 6-3 that form the common electrode 6, and the transparent electrodes 1-2 and 2- that form a part of the transparent conductive positive films 1 and 2 respectively. A negative voltage is applied to 2, but the polarity of the voltage may be the opposite. Various types of common electrodes 6 can be considered. FIG. 2 shows some examples. The common electrode 6 shown in FIG. 2A is configured by a transparent electrode 6-5, a film 6-4, a film 6-6, and a transparent electrode 6-7 being contacted in this order. The transparent electrodes 6-5 and 6-7 are in contact with the polymer liquid crystal composite films 3-1 and 3-2, respectively. This structure has a structure in which the conventional light control film shown in FIG. 3, that is, two light control film elements are stacked, and has an advantage that it is not necessary to develop a special common electrode. Where film 6-4
Needless to say, 6 and 6-6 may use a glass substrate.

The other arrangements, connections and functions of the transparent conductive films 1 and 2, the high frequency power source 4 and the switch 5 are the same as those shown in FIG. 1 and will not be described repeatedly. It can be said that the structure shown in FIG. 1 is obtained by stacking two conventional light control film elements and using the overlapping films in common. The common electrode 6 shown in FIG. 2B has the same structure as that shown in FIG. 1, but is shown again for comparison with FIG. 2A. Here, only one film 6-1 sandwiched in the center of the common electrode 6 is used, and the film thickness of the light control film is reduced and the production cost is reduced as compared with the one using two films in FIG. 2A. There are advantages. The film 6-1 here may be a glass substrate or may be a metal mesh. In the case of a metal mesh, it is preferable to use a thin wire mesh for the purpose of not reducing the light transmittance.

The other arrangements, connections and functions of the transparent conductive films 1 and 2, the high frequency power source 4 and the switch 5 are the same as those shown in FIG. 1 and will not be repeatedly described.

[0016]

According to the light control film of the polymer liquid crystal composite film of the present invention, since a plurality of light control film elements are stacked, the contrast is improved and it is easy to see.

[Brief description of drawings]

FIG. 1 is a sectional perspective view of a light control film of the present invention.

FIG. 2A is a sectional view showing an example of a common electrode used for the light control film of the present invention, and B is a sectional view showing another example of a common electrode used for the light control film of the present invention.

FIG. 3 is a sectional perspective view of a conventional light control film.

FIG. 4 is a comparative cross-sectional view of a conventional light control film and a light control film of the present invention.

Claims (1)

[Claims] 1. A light control film comprising a plurality of light control film elements of a polymer liquid crystal composite film having substantially the same characteristics, which are stacked.