Device for temperature-dependent regulation of the passage of energy through a light-permeable surface

The present invention relates to a device for regulating energy flow through a light-transmitting area comprising a first polarizing layer, a second polarizing layer and a switching layer that is disposed between the two polarizing layers and changes the polarization properties of polarized light as a function of temperature, said layers polarizations are characterized by an appropriate selection of their permeability towards transmission and their degree of polarization. The present invention further relates to a process for manufacturing a device according to the present invention and the use of such a device for influencing transmission of light and / or energy flow into the interior space as a function of temperature.

[0002] Energy efficiency of buildings is a factor of weight increasing with increasing energy costs. Windows and glass facades are critical parts of the building, through which most of the building's heating energy is lost at low outdoor temperatures or through the parts through which energy flows into the building in the event of intense sun exposure.

[0003] There is therefore a need to provide devices that control light transmittance and thus energy flow through windows or glass areas. In particular, there is a need to provide devices that are capable of matching the flow of energy through the glass regions to the conditions (heat, cold, high insolation, low insolation) prevailing at a specific moment in time.

[0004] For the purposes of the present invention, the term light means electromagnetic radiation in the UV-A, VIS and NIR range. In particular, this term means radiation that is not absorbed or is absorbed only in a negligible range by materials normally used in windows (e.g. glass). According to the definition usually used in the field of radiation physics, UV-A light means radiation having a wavelength from 320 to 380 nm,

- VIS light means radiation having a wavelength from 380 nm to 780 nm, and NIR light means radiation having a wavelength from 780 nm to 3000 nm. Therefore, for the purposes of the present invention, the term light means radiation having a wavelength from 320 to 3000 nm.

[0005] In the cold season, it is desirable that the building receives the maximum amount of radiation and thus the energy it transports through the glass regions. This allows you to save on heating and lighting expenses.

[0006] On the other hand, in the warm season, the smallest possible energy supply to the building through the glass regions is desirable. This makes it possible to achieve a more pleasant indoor climate or to save on air conditioning costs. In addition, in such cases, it may be desirable to reduce the intensity of incident light, for example to reduce glare due to direct sunlight.

[0007] There is, therefore, a need to provide switching elements that regulate the influencing of energy in the form of light into internal spaces, for example through windows or other glass regions. In particular, there is a need to provide switching elements that automatically adjust the light transmission control to the prevailing conditions as described above (intelligent windows). In addition, there is a need to provide switching elements that operate in an energy efficient manner, can be installed with the lowest possible technical complexity, are technically reliable and meet aesthetic requirements. Further aspects are the ability to easily process such a switching element,

[0008] The publications of inventions of US 2009/0015902 and US 2009/0167971 disclose temperature-responsive devices that contain a liquid crystal center in a layer between two highly effective polarizers. Switching between a state having relatively high light transmittance and a state having relatively low light transmittance is achieved in them

Through the phase transition of the liquid crystal medium from the nematic state to the isotropic state without the need for voltage.

[0009] Publication US 2009/0167971 discloses the features of the preamble of claim 1.

Nevertheless, devices of this type have the disadvantage that they have light transmittance in a state with relatively high light transmission, theoretically up to 50%, and practically at most from 30 to 40%. In addition, when the transmittance in a state with relatively low light transmission is in fact equal to zero, it means that the device is completely darkened.

[0011] For the use of such devices in practice, for example in buildings or vehicles, it would nevertheless be desirable for the devices to have a permeability in a state with relatively high light transmittance (= open state) of 50 to 70%. Otherwise, it would give the impression of significantly darkening the window in the open state of the device.

Furthermore, for practical applications, it is desirable that the device is not completely dim in a state having a relatively low permeability (= closed state), but instead has a residual permeability. The minimum permeability of 7% is considered subjectively still pleasant in the case of windows.

[0013] The publication of the patent application US 2011/0102878 discloses that relatively thin polarizers having increased permeability may be used instead of highly efficient polarizers in devices according to publications US 2009/0015902 and US 2009/0167971. According to the scope of the disclosure of this application, the effect of this was to increase the permeability in the open state of the device. However, for such an embodiment, the switching range of the device, i.e. the difference in light transmission between the open state and the closed state, becomes smaller.

[0014] In the case of devices for regulating the energy flow, it is desirable to be able to pre-determine both brightness transmittance as well as

- also the switching range of the device to the requirements in a given case. For example, for some applications, it may be advantageous for the device to have a very large switching range. For other applications, it may be advantageous to combine a relatively large switching range with relatively high light transmittance.

[0015] The inventors of the present invention have found that the above objects can be achieved by the appropriate selection of parameters P (degree of polarization) and T1 (permeability towards transmission) of said polarizers.

[0016] US 2009/167971 A1 discloses a device for regulating the flow of energy through a translucent surface, consisting of two polarizing layers and a switching layer interposed between them, which changes the polarization properties of polarized light in relation to temperature.

The essence of the present invention is a device for regulating energy flow through a light-transmitting area, which comprises the following layers:

- the first polarizing layer,

- a second polarizing layer, and

- a switching layer located between the two polarizing layers that changes the polarization properties of polarized light as a function of the temperature at which the two polarizing layers, in an identical or different manner, have a polarization degree P in the range of 20-85% and transmittance in the direction of transmission T1 in the range of 70-100%, determined at a wavelength of 550 nm, and wherein one or both of the polarizing layers comprise a layer of a liquid crystal medium and one or more dichroic dyes.

[0018] The use of polarizing layers that have said polarization degrees P and said permeabilities in the direction of T1 transmission results in devices that have a satisfactory dark state permeability of at least 7.5%. In addition, a satisfactory brightness transmittance of at least 30%, preferably at least, is obtained

At least 40%. Furthermore, there is a switching range of at least 5%, preferably at least 7.5%.

[0019] Furthermore, an appropriate selection of these two parameters P and T1 from said ranges makes it possible to manufacture devices in which brightness and switching range can be set independently of one another.

[0020] Parameters P and T1 are, as is generally known to the person of ordinary skill in the field of devices containing polarizing layers, defined as follows:

P is obtained from the following equation P = (T1-T2) / (T1 + T2) from the values ​​for T1 and T2. T1 means the transmission of the polarizer towards the transmission at a wavelength of 550 nm. The direction of transmission means the orientation of incident polarized light in which the highest permeability through the polarizer occurs. T2 is the polarity of the polarizer in blocking direction at 550 nm. The blocking direction means the orientation of the incident polarized light in which the least transmission through the polarizer occurs.

[0021] The bright transmittance of the device, as indicated above, means transmittance by a device occurring in the switching state with relatively high light transmittance. Accordingly, the dark-state transmittance of the device means transmittance by a device that is in a switching state with relatively low light transmission. These permeabilities are again defined at a wavelength of 550 nm.

[0022] The switching range of the device is the difference between the brightness transmittance values ​​and the dark state transmission.

[0023] It should be noted that the optical values ​​T1, T2, P and brightness transmittance, dark state permeability and switching range are generally to be determined according to the present invention at a wavelength of 550 nm, unless otherwise indicated.

[0024] For the purposes of the present invention, the term energy means energy of electromagnetic radiation (light energy) in the UV-A, VIS and NIR range. In particular, this term means the energy of light that is absorbed by materials normally used in windows (e.g. glass) or is absorbed only to a negligible extent.

According to the invention, two switching conditions of the device include a switching state having a relatively high light transmittance through the device (bright state) and a switching state having a relatively low light transmission through the device (dark state).

[0026] According to generally known laws of physics, the high light transmittance of the device results in a high energy supply to the interior space into which the light transmitting area is applied to the device. In turn, low light transmission through the device results in a small supply of energy to the internal space. Such a device thus regulates the supply of energy to the internal space by switching this light transmission.

[0027] The device undergoes switching from a switching state with a relatively high light transmission to a switching state with a relatively low light transmission as a function of temperature. Switching states of such a device are consequently related to different temperature ranges of the device. The switching of the device preferably takes place gradually in a temperature range between 0 and 80 ° C, preferably between 10 and 70 ° C, and particularly preferably between 20 and 60 ° C.

[0028] According to a preferred embodiment of the invention, the switching state with relatively high light transmittance occurs at relatively low device temperatures, and a switching state with relatively low light transmittance occurs at relatively high temperatures of the device. Accordingly, the bright state of the device is preferably at temperatures below 0 ° C, particularly preferably below 10 ° C, and most preferably below 20 ° C. The dark state of the device preferably occurs at temperatures above 80 ° C, more preferably above 70 ° C, and more preferably above 60 ° C.

[0029] The operation of the device is based on the incident light polarized by the first polarizing layer. This means that predominantly light with some polarizing properties is passed through. The switching layer is located after the first polarizing layer. In the first state it does not affect the polarizing properties of the light passing through it. Then the light encounters a second polarizing layer, which is located behind the switching layer. Regarding the orientation of the directions of transmission of the polarizing layers relative to each other, a part of the light can now also pass through the second polarizing layer. In the second of two switching states, the switching layer that changes the polarity changes the polarizing properties of the light passing through it. Therefore, a larger or smaller portion of the polarized light can now pass through the second polarizer, depending on the way in which the polarization properties of the light have been changed by the switching layer. In any case, changing the light polarization properties of the switching layer in its second state initiates a change in the light transmittance of the device compared to the first state of the switching layer in which it does not affect the light polarization properties. depending on the way in which the polarization properties of the light have been changed by the switching layer. In any case, changing the light polarization properties of the switching layer in its second state initiates a change in the light transmittance of the device compared to the first state of the switching layer in which it does not affect the light polarization properties. depending on the way in which the polarization properties of the light have been changed by the switching layer. In any case, changing the light polarization properties of the switching layer in its second state initiates a change in the light transmittance of the device compared to the first state of the switching layer in which it does not affect the light polarization properties.

[0030] According to a preferred embodiment of the present invention, said two polarizing layers are linear polarizers whose preferential polarization directions are rotated relative to each other by an angle of 60-120 °, preferably 75-105 °, and particularly preferably by an angle of 80 to 100 °. In one of the two states mentioned, the switching layer does not rotate the plane of light polarization or does so only minimally. In the second of the two states, the polarization plane is rotated by an angle which corresponds to the angle by which the preferential polarization directions of the polarizers are rotated relative to each other, or which differs only slightly from this angle, e.g. by 1-10. In this configuration, the light passing through the first polarizer also passes through the second polarizer, if the switching layer is in a state in which it rotates the polarization plane of light. The active state of the switching layer therefore corresponds to the bright state of the device. For comparison, if the switching layer is in its inactive state, i.e. in a state in which

- it does not rotate the plane of polarization of light, the light falling on the second polarizer can not pass through it, because the preferential polarization directions of the two polarizers are rotated relative to each other. In this embodiment, the inactive state of the switching layer thus corresponds to the dimmed state of the device.

The active state of the switching layer is associated with the optically anisotropic state, preferably the liquid crystal state, the switching layer, and the inactive state of the switching layer is associated with the substantially isotropic state of the switching layer.

The switching layer in the optically anisotropic condition preferably rotates the plane of polarization of the linearly polarized light by an angle of 10 ° or more, whereas in the isotropic state it does not rotate the plane of polarization of the linearly polarized light or does this negligibly. Exceptionally, the plane of polarization of the linearly polarized light is rotated by an angle greater than 40 °, particularly preferably by an angle greater than 70 °. Most preferred are rotation angles of 70 to 110 ° or even greater angles of 80 to 100 °. However, rotation angles are possible that are greater than the indicated preferred rotation angles by a multiple of 180 °.

[0033] According to the invention, the switching operation between these two switch states does not occur suddenly at a certain temperature, but occurs gradually in the transition region that is in the temperature range. This temperature range of the transition region preferably has a width of 5 to 100 degrees Celsius, i.e. it extends, for example, from 15 to 110 ° C. This temperature range is preferably between 10 and 50 degrees Celsius. In the temperature range of the transition region, the permeability of the device changes gradually through indirect transmission values ​​from the brightness state permeability value to the dark state permeability value.

[0034] The device is preferably switched only under the influence of temperature control. Therefore, it preferably does not contain any devices for electrical triggering of switching operations. Preferably, it does not contain any

- wires, cables, connections or electrical circuits. In addition, it is advantageous not to trigger the release electrically from the outside or to supply electricity, i.e. to create a system that is autonomous per se.

[0035] The energy flow preferably takes place through the area of ​​transmission of light into the interior space. The interior space is preferably the interior of a building, e.g. a residential building, an office building or a building used for commercial purposes. Alternatively, the interior space can also be the interior of a vehicle, e.g. a car, or the interior of a transport container, e.g. a forwarding container. The device may be used according to the invention in any desired interior spaces as long as they have limited air exchange with the environment and have surfaces that limit the transmission of light through which energy flows from the outside in the form of light energy. The present invention relates in particular to interior spaces,

[0036] Light transmitting areas such as windows or ceilings having a size larger than 0.5 m are preferred²preferably greater than 1 m²and even more preferably ₂ greater than 3 m². This is due to the fact that high energy consumption into the internal space takes place through such areas if they are subjected to solar irradiation. Also preferred are light-transmitting areas that are exposed to strong sunlight as a result of their spatial orientation and / or the geographical or climatic location of the building.

[0037] The device is preferably arranged over the entire surface of the light-transmitting area in such a way that light transmission through this area can be adjusted as completely as possible. In one preferred embodiment, the cover is implemented by means of a single device. However, in an alternative embodiment, the cover can also be implemented by means of a plurality of devices that are either directly adjacent to each other or spaced apart.

[0038] In one preferred embodiment, the light transmission area is a glass pane or plexiglass glass. In the case of window panes, a multi-pane insulating glass is preferred. According to a preferred embodiment, the device of the present invention is applied directly to such a window.

[0039] This type of application can be implemented by modifying the existing system or by complete reinstallation.

[0040] According to a preferred embodiment, the device according to the invention is mounted inside a multi-pane insulating glass or on the outside of a glass of this type. It is generally advantageous to use on the side of the pane directed to the inner space or in the space between two glass panes in the case of multi-pane insulating glass. However, in certain special cases, other combinations are also acceptable and preferred. One skilled in the art will be able to consider the advantages and disadvantages of various configurations with respect to the device's durability, optical and aesthetic properties, practicalities regarding glass cleaning and the reactivity of the device relative to temperature changes, and choosing the optimal configuration in a given case.

[0041] According to preferred embodiments, the device according to the invention is characterized in that it has a surface extent of at least

2 2 2 2 0.05 m²preferably from 0.1 m² up to 20 m²and particularly preferably from 0.2 m² up to 5 m².

[0042] According to the present invention it is preferred that the polarizing layers of the device have, in an identical or different way, the degree of polarization P in the range of 30-85% and transmittance in the direction of transmission T1 in the range of 75 to 100%, these values ​​being determined at a wavelength of 550 nm. For the polarizing layers, the polarization degree P in the range of 35 to 80% and the transmissivity T1 in the range from 75 to 100% are extremely advantageous.

Within the ranges of P and T1 preferred for the present invention, some combinations of ranges of values ​​for P and T1 have been found for which there are some characteristics of the device for permeability

- bright state and switching range. The darkness permeability remains above the minimum value of 7%.

[0044] A device having the largest possible switching range is obtained if P for the polarizers is selected, identically or differently, in the range of 45-85%, and T1 is selected in the range of 75-100%. Preferably, P is selected in the range of 55-85% and T1 in the range of 80-100%. Exceptionally, P is selected from 65-85% and T1 in the 85-100% range.

[0045] In this case, the minimum values ​​for light transmission and dark transmission are used.

[0046] A device having an average switching range combined with a medium brightness transmission is obtained if P for the polarizers is selected, identically or differently, in the range of 30 to 85% and T1 is selected in the range of 80 to 100%. Preferably P is selected in the range of 40 to 75% and T1 is selected in the range of 90 to 100%. In this case, the minimum values ​​given above for dark permeability are used.

[0047] A device having the highest possible brightness permeability is obtained if P for the polarizers is selected, identically or differently, in the range of 25 to 60%, and T1 is selected in the range of 90 to 100%. Preferably, P is selected from 30 to 40% and T1 in the range from 95 to 100%. The minimum values ​​given above for dark permeability and switching range are used here.

[0048] The values ​​of P and T1 for the polarizing layers can be set independently of one another. Suitable methods are known to those skilled in the art. These include, for example, changing the thickness of the polarizing layer, changing the degree of unification of orientation in the polarizing layer, and changing the concentration of light absorbing elements in the polarizing layer.

In the case of polarizers containing a liquid crystal medium and a dichroic dye, the parameters P and T1 can be varied independently of each other, e.g. by changing the liquid crystal medium and changing the concentration of the dye.

- dichroic. In this respect, the corresponding working examples are clearly set forth below.

[0050] In many cases, it will be necessary to produce a relatively large number of different polarizers with variations of the production parameters indicated above and to measure their P and T1 values. The empirical correlation between production parameters (e.g., stretch and dye concentration) and pairs of T1 and P values ​​may be recognized therefrom and may form a basis for a person skilled in the art, in particular to enable the generation of polarizers having the desired T1 and P values.

[0051] The invention furthermore relates to a method of manufacturing an apparatus for regulating the energy flow through a light-transmitting area, which comprises the following layers:

- the first polarizing layer,

- a second polarizing layer, and

- a switching layer between the two polarizing layers that changes the polarization properties of the polarized light as a function of temperature;

which method is characterized in that said two parameters of polarization P and transmittance towards transmission T1 for the polarizing layers are selected independently of each other by changing one or more production parameters selected from the layer thickness, the orientation degree of the polarizing layer, the concentration of the incorporated substance , degree of alignment of the incorporated substance, absorption properties of the incorporated substance, structure of the incorporated substance, dichroism of the incorporated substance and aggregation properties of the incorporated substance.

[0052] The structure of the incorporated substance means its molecular structure, in particular the length-to-width ratio. The greater the ratio of the length-width of a given substance, the greater the degree of alignment of the setting.

[0053] The aggregation properties of the incorporated substance mean in particular the ability to form chains of individual molecules or individual atoms of the substance.

In this process, the degree of polarization P is preferably selected in the range of 20-85%, and permeability in the direction of transmission is preferably chosen in the range of 70-100%. Exceptionally, P is selected from the 30-85% range and T1 is selected from the range of 75 to 100%.

[0055] Preferred embodiments of the polarizing layers and the switching layer, which are an indication for the device of the present invention, are also beneficial for said process.

[0056] The invention further relates to the use of the device according to the invention for influencing the energy flow through the light transmitting area as a function of temperature. It is advantageous to apply to the influence of energy to the internal space through the light transmitting area as a function of temperature.

[0057] The energy flow in an application of the present invention is affected by a device that changes its light transmittance between a switching state with relatively high light transmittance (bright state) and a switching state with relatively low light transmission (dark state). The switching operation is controlled by the temperature and proceeds in the preferred ranges for the switching operations as indicated above.

[0058] The use according to the invention is carried out without the use of an electrical voltage. Such application therefore does not require any energy, in particular electricity.

According to the invention, the device has two or more polarizing layers, one of which is on one side of the switching layer and the other is on the opposite side of the switching layer. The switching layer and the two polarizing layers are preferably arranged parallel to each other. The polarizing layers have the values ​​of parameters P i

- [0102] B1

T1, which are indicated above according to the invention, and preferably values ​​of parameters P and T1, which have been indicated as being preferred.

[0060] The polarizing layers may be linear polarizers or circular polarizers. Precisely, the two polarizing layers are preferably contained in such a device. In this case, it is further preferred that the two polarizing layers be linear polarizers or both polarizing polarizens are circular polarizers.

[0061] Extremely preferably, the two polarizing layers are the same or different, adsorptive or reflective linear polarizers. More preferably, the two polarizing layers are absorptive linear polarizers.

[0062] A reflective polarizer in the sense of the present invention reflects light having a single polarization direction or one type of circularly polarized light, which is transparent for light having a different polarization direction or other type of circularly polarized light. Accordingly, the absorption polarizer absorbs light having one polarization direction or one type of circularly polarized light, whereas there is transparency for light having a different polarization direction or for another type of circularly polarized light.

If there are two linear polarizers in the device, according to the invention it is preferred that the polarization planes of the two polarizers are rotated relative to each other by an angle of 70 to 110 °, more preferably of 80 to 100 °, and even more preferably of 85 to 95 ° .

[0064] According to a preferred embodiment of the present invention, one or both polarizing layers are formed of a liquid crystal media layer and one or more dichroic dyes. The liquid crystal center preferably comprises two or more, more preferably 5 or more and very particularly preferably 7 or more different liquid crystalline compounds.

[0065] For the purposes of the present invention, the term liquid crystal compound means a compound that exhibits liquid crystal properties in certain embodiments of the present invention.

Conditions, in particular a compound that forms a nematic liquid crystal layer under certain conditions.

[0066] Such liquid crystal compounds may be selected depending on the requirements of the liquid crystal compounds known to those skilled in the art, as the case may be. Liquid crystalline compounds with limited size and molecular weight (small molecules) are preferred. The liquid crystalline compounds having a molecular weight of no more than 1000 Da, particularly preferably no more than 800 Da, and most preferably no more than 600 Da, are particularly preferred.

[0067] Suitable liquid crystal centers for use in the polarizing layers are those that have high temperature stability and are stable to light radiation. They preferably have a clarification temperature higher than 50 ° C, particularly preferably higher than 70 ° C, and most preferably higher than 90 ° C.

[0068] According to preferred embodiments of the present invention, the liquid crystal center comprises one or more polymeric compounds. In one preferred embodiment, the polymer is in the form of a continuous phase in the polymer network (polymer network systems). The polymer network preferably penetrates the liquid crystal medium and / or this network is dissolved in the liquid crystal medium in such a way that an optically uniform appearance is obtained. It is preferably formed by polymerizing mono- or diacrylate monomers that are added to the liquid crystal media. Such a liquid crystal center preferably is present in a mixture with a polymer compound in a proportion of greater than 60%, more preferably in a proportion of 70 to 95%.

[0069] Useable dichroic dyes are the compounds disclosed in Liquid Crystals, Applications and Uses, 1992, World Scientific Publishing, Editor B. Bahadur, pp. 73-81. Preferred dyes are anthraquinone, naphthachinone, benzoquinone, perylene and tetrazine dyes and compounds containing one or more azo groups or one or more Schiff's bases.

[0070] The dichroic dyes are preferably selected from the following compounds:

<img file="PL2798397T3_D0001.tif" />

<img file="PL2798397T3_D0002.tif" />

<img file="PL2798397T3_D0003.tif" />

OH O OH

<img file="PL2798397T3_D0004.tif" />

[0071] The dyes are preferably present in the mixture at a concentration of from 0.01 to 5% by weight, more preferably from 0.05 to 1% by weight. They are preferably dissolved in a liquid crystal medium.

[0072] Furthermore, it is preferred to use two or more dyes together. The use of exactly two or three dyes is particularly advantageous. The dyes used are preferably selected in such a way that their absorption spectra complement each other to form a neutral, i.e. colorless, impression for the human eye. However, in certain embodiments, it may also be advantageous to use one or more dyes that produce a colorful impression.

[0073] The switching layer of the device of the present invention preferably comprises a liquid crystal medium that contains at least one liquid crystal compound. The switching layer preferably comprises a mixture of different liquid crystalline compounds. The switching layer particularly preferably comprises at least 5 or at least 15 different liquid crystalline compounds.

[0074] Such liquid crystal compounds may be selected depending on the requirements of the liquid crystal compounds known to those skilled in the art, as the case may be. Liquid crystalline compounds of limited size and molecular weight (small molecules) are preferred. It is particularly preferred that the liquid crystalline compound has a molecular weight of not more than 1000 Da, more preferably no more than 800 Da, and most preferably no more than 600 Da.

[0075] A mixture of such liquid crystal compounds (or in the case where only one liquid crystal compound is used, a single liquid crystal compound) preferably has a clarification temperature between -20 and 200 ° C, more preferably a clarification temperature between 10 and 180 ° C.

For use as the liquid crystal medium, mixtures of the liquid crystal compounds disclosed in the publication of the inventions of the inventions WO 2011/134582, WO 2011/144299, WO 2011/154077 and mixtures disclosed in still unpublished applications EP 10008779.0 and EP 10013797.5 are particularly preferred.

[0077] The liquid crystal center of the switching layer preferably undergoes a change from the nematic state to the isotropic state during the switching operation as the temperature increases. The nematic state is in this case preferably associated with the state of the device with relatively high light transmittance, and the isotropic state is associated with the state of the device with relatively low light transmittance.

[0078] The liquid crystal medium may further comprise one or more polymeric compounds. In this case, the medium is extremely preferably one of the liquid crystal centers containing polymeric compounds, which are described in the unpublished application of the invention to date.

- 2)

EP 11008518.0. With regard to further information regarding polymer network systems, reference is made herein to the disclosure of the publication of EP application applications 452460, EP 313053 and EP 359146.

[0079] According to one preferred embodiment of the invention, the switching layer comprises a twisting nematic layer. The twisting of the preferential direction of the liquid crystal compounds is preferably carried out using two or more leveling layers, at least one of which is on one side of the switching layer, and at least one is on the opposite side of the switching layer.

[0080] The device of the present invention preferably comprises at least one backing layer, which is preferably made of glass, polymer or ITO. The base layer is preferably rigid.

[0081] Furthermore, the device according to the invention may comprise one or more further functional layers in addition to the polarizing layers and the switching layer. In the device according to the invention, the following types of individual functional layers or any other type of such layers can be used. These layers are preferably passive, i.e. they can not change their function.

[0082] Such functional layers can be advantageously selected from weatherproofing layers, damage from hard objects, aging and UV radiation. Such security layers, their effects and methods for their application and use are known to those skilled in the art.

[0083] Further preferred layers can be selected from layers that block light having a certain wavelength or reduce its transmission, for example light

NIR or light having a certain wavelength (color) in the visible range. Preferred are NIR radiation preventive layers, e.g. containing a cholesterol liquid crystal material, a ceramic material, a metal or a metal oxide.

[0084] Additional preferred functional layers are selected from leveling layers, known to those skilled in the art, for liquid crystal compounds. Preferably, at least two leveling layers are used, at least one leveling layer being on one side of the switching layer and at least one leveling layer being on the opposite side of the switching layer. Leveling layers can also act as base layers, which means that the device equipped with such leveling layer does not require any backing layers. In a preferred embodiment of the invention, the leveling layers comprise polyimide starts or polyacrylate starts.

[0085] The device according to the invention preferably has the structure depicted in Fig. 1. The numeral reference 1 indicates the device, the numeral reference 2 indicates the switching layer, and the reference numerals 3a and 3b indicate the polarizing layers. Figure 1 shows the basic arrangement of the layers and it is not intended, for example, to exclude the possibility of placing further functional layers, e.g. one or more leveling layers and / or one or more security layers that block external influences or light at a certain wavelength, between the layers shown or outside the shown layer system.

[0086] Figure 2 illustrates another preferred structure of a layer system in which a system comprising a switching layer and two polarizing layers is located on the substrate layer 4.

[0087] The working examples below disclose advantageous embodiments of the device according to the present invention. One skilled in the art of the invention will become familiar with these examples and will recognize the principle of operation of the invention and will easily apply it to construct further embodiments not expressly described in the present application. These examples do not constitute a limitation of the scope of the invention, in particular to the solutions described herein.

Working examples

1. Production of polarizing layers

[0088] The following components were used in the production of the polarizing layers:

LC A mixture:

<td>LC mixture</td><td>%</td>

<td>CP-3-N</td><td>20</td>

<td>PGU-5-N</td><td>10</td>

<td>PPL-1O-1</td><td>11</td>

<td>PZP-1O-5</td><td>16</td>

<td>PGU-3-F</td><td>9</td>

<td>CPZG-3-N</td><td>5</td>

<td>CPZG-4-N</td><td>5</td>

<td>CPZG-5-N</td><td>5</td>

<td>CCZPC-3-3</td><td>3</td>

<td>CCZPC-3-4</td><td>3</td>

<td>CGPC-3-3</td><td>5</td>

<td>CGPC-5-3</td><td>4</td>

<td>CGPC-5-5</td><td>4</td>

LC B mixture:

<td>LC mixture</td><td>%</td>

<td>PGU-3-N</td><td>2</td>

<td>PZG-4-N</td><td>9</td>

<td>PGU-5-N</td><td>9</td>

<td>PPL-1-5</td><td>10</td>

<td>PPL-1O-1</td><td>17</td>

<td>PZP-1O-5</td><td>16</td>

<td>CP-3-N</td><td>12</td>

<td>PP-2-N</td><td>10</td>

<td>PGU-3-F</td><td>9</td>

<td>CPZG-3-N</td><td>3</td>

<td>CPZG-4-N</td><td>3</td>

- 2)

Dye mixture:

<td>Dye</td><td>Participation</td>

<td>= · "·" ^IN ?.,</td><td>37</td>

<td>^cAf&gt; A / = \^N V- / _ / = \ / \ 'W^_about'\ /⁼'\ ._ V # ^CIH"</td><td>76</td>

<td>^{csh ,,}XZH0 ^^{n = n_}"Q^{n = -N}Q ~^{-N = N-}ABOUT^_n'^h\_h</td><td>90</td>

[0089] The following polarizing layers EP-1 to EP-4 were made from the components indicated below:

<td></td><td>LC mixture</td><td>The proportion of the dye mixture</td>

<td>EP-1</td><td>AND</td><td>0.1%</td>

<td>EP-2</td><td>AND</td><td>0.3%</td>

<td>EP-3</td><td>AND</td><td>0.5%</td>

<td>EP-4</td><td>B</td><td>0.3%</td>

[0090] In addition, the following VP-1 to VP-3 polarizing layers were produced or commercially purchased (VP-3) for comparative purposes:

<td></td><td>LC mixture</td><td>The proportion of the dye mixture</td>

<td>VP-1</td><td>AND</td><td>1%</td>

<td>VP-2</td><td>B</td><td>1%</td>

<td colspan="3"></td>

<td>VP-3</td><td colspan="2">the ITOS XP38 absorption polarizer</td>

[0091] The following values ​​of T1, T2 and P (determined for 550 nm) were obtained for such polarizing layers:

- 2)

T1: permeability of the polarizer layer towards the transmission; T2: permeability of the polarizer layer in the blocking direction;

P: the degree of polarization can be determined on the basis of the equation:

P = (T1-T2) / (T1 + T2)

<td></td><td>T1 /%</td><td>T2 /%</td><td>P /%</td>

<td>EP-1</td><td>94.1</td><td>60.9</td><td>21.5</td>

<td>EP-2</td><td>86.1</td><td>22.2</td><td>58.9</td>

<td>EP-3</td><td>79.7</td><td>9.1</td><td>79.5</td>

<td>EP-4</td><td>79.1</td><td>26.3</td><td>50.2</td>

<td>VP-1</td><td>63.3</td><td>0.7</td><td>97.8</td>

<td>VP-2</td><td>48.0</td><td>1.2</td><td>95.0</td>

<td>VP-3</td><td>71.5</td><td>0.1</td><td>98.6</td>

[0092] After generating and measuring a relatively large number of polarizing layers produced in a number of different ways, it is possible to observe an empirical correlation between the production parameters and the obtained pair of T1 and P values. In the example, it can be seen that the increase P and the reduction T1 occur with the increase dye concentration for the same LC mixture. When changing from mixture A to mixture B (compare EP-3 and EP-4), it is possible to achieve a significant reduction in the value of P at constant T1.

[0093] Corresponding polarizing layers can be obtained as described for any desired pair of T1 and P values ​​by using different concentrations of the dye mixture and the use of different LC mixtures.

2. Generation of devices [0094] Devices E-1 to E-4 and comparative devices V-1 to V-3 are produced by placing the polarizing layers described above in each case on the upper and lower sides of the twisting nematic cell. A twisting nematic cell contains leveling layers and a liquid crystal layer and is produced by processes that are generally known to the person skilled in the art.

[0095] For the devices manufactured in such a way, permeability is determined in each case with a relatively high light transmittance (brightness transmittance) and permeability in a state with relatively low light transmittance (dark permeability). Switching ranges are determined from the difference between these two values. All values ​​were again determined at 550 nm.

<td></td><td>Clear light transmittance /%</td><td>Dark permeability /%</td><td>Range Switching /%</td>

<td>E-1</td><td>62.8%</td><td>57.3%</td><td>5.5%</td>

<td>E-2</td><td>39.5%</td><td>19.2%</td><td>20.3%</td>

<td>E-3</td><td>32.2%</td><td>7.3%</td><td>24.9%</td>

<td>E-4</td><td>34.8%</td><td>20.8%</td><td>14%</td>

<td>V-1</td><td>20.0%</td><td>0.5%</td><td>19.5%</td>

<td>V-2</td><td>11.5%</td><td>0.6%</td><td>10.3%</td>

<td>V-3</td><td>37.2</td><td>~ 0%</td><td>37.2%</td>

[0096] In the above table, it is seen that all the devices of the present invention have an acceptable dark permeability (about 7% or more). The values ​​for the transmittance of the bright state and the switching range can be set independently of each other (compare, for example, E-3 and E-4). This is highly desirable for the intended use, because the advantages of the wide switching range and the advantages of the high brightness permeability can be thus balanced against each other and the desired combination of these two values ​​can be set.

In the range of parameters P (20-85%) and T1 (70-100%), which are selected for devices E-1 to E-4, preferred values ​​are obtained for both brightness transmissibility and for the switching range ( see table above).

[0098] Comparative devices according to the prior art (V-1 to V-3), which showed values ​​of P and T1 parameters outside these ranges, were characterized by unfavorable dark state transmission from the point of view of using these devices in the windows.

[0099] Figures 3-8 show the transmission spectra obtained for devices E-1 to E-4 and V-1 and V-2 in the range from 400 to 900 nm, each in the light state ( curve 1) and in the dark state (curve 2).

Fig. 3 shows the permeability spectrum for the E-1 device according to the present invention.

Fig. 4 shows the transmission spectrum for the E-2 device according to the present invention.

Fig. 5 shows the transmission spectrum for the E-3 device of the present invention.

Fig. 6 shows the transmission spectrum for the E-4 device according to the present invention.

Fig. 7 shows the permeability spectrum for a comparison device

V-1.

Fig. 8 shows the permeability spectrum for a comparison device

V-2.

3. Alternative manufacturing processes for polarization layers [0100] According to a further embodiment of the invention, the polarizing layers are made by admixing the polymerizable monomers in addition to the LC mixture and the dye mixture. These monomers are, for example, acrylates such as monoacrylates, diacrylates and multifunctional acrylates, or epoxides or vinyl ethers. It is possible to use mixtures of monomers, e.g. mixtures of mono- and diacrylates or mixtures of epoxides and vinyl ethers. Monomers may contain mesogenic groups. The mixture containing the liquid crystal medium, dye and monomers is then polymerized to a layer. Such polymerization can be effected, for example, by excitation with UV radiation.

[0101] The above-described process makes it possible to produce extremely resistant and temperature-stable polarizing layers for the devices of the present invention.

[0102] According to a further example, the polarizing layers are produced by stretching a polymer film containing polyvinyl alcohol (PVA). Iodine is then incorporated into such films.

[0103] Polarizing layers having different degree of PVA stretch, different iodine concentration and different thicknesses are produced. For the polarizing layers obtained, the values ​​for permeability in the direction of transmission (T1) and the degree of polarization are determined. After generating and performing measurements of a relatively large number of polarizing layers produced by different methods, it is possible to observe an empirical correlation between the production parameters and the obtained pairs of T1 and P values. In this way, corresponding polarizing layers can be created for any desirable value pairs T1 and P.

Merck Patent GmbH Plenipotentiary:

- 2)