KR20210016700A - Cover Dust Laminate and Head Up Display including the Cover Dust Laminate - Google Patents

Abstract

The present application can provide a cover dust laminate in which a so-called reddening phenomenon is not induced even when driven or maintained in very severe conditions (e.g., extremely high temperature conditions). In addition, the present invention can provide a head-up display which is applied with the cover dust laminate so as to prevent reddening of internal components such as an image generating device, and the like, while realizing a clear picture quality, and in which the luminance ratio of each screen is appropriate when two independent screens are displayed.

Description

Cover Dust Laminate and Head Up Display including the Cover Dust Laminate}

The present application relates to a cover dust stack and a head-up display including the same.

The Head Up Display (HUD) is a device that visualizes and displays driving information of a vehicle in front of the driver's field of view as a virtual image.

The head-up display 10 includes, for example, an image generating device 20 that generates an optical signal corresponding to an image, as shown in FIG. 1, and a cover dust stack for preventing deterioration of internal components due to external light, etc. 100), light control means for directing the light signal from the image generating device 20 to the windshield 50 on which an image is displayed after passing through the cover dust stack 100 (reflector 40 and/ Or a beam splitter, etc.).

The cover dust stack 100 has played a role of preventing deterioration of internal components, for example, the image generating apparatus 20 due to external light. However, since the conventional cover dust stack 100 includes an optical stack to which a reflective polarizer is applied, external light is reflected back to the outside and enters the driver's field of view, so that a clear screen cannot be recognized. there was.

In addition, the head-up display is particularly applied to a vehicle and is often exposed to a high temperature environment and/or an environment in which temperature changes in summer and winter are large, and thus durability of the cover dust laminate has been problematic.

Accordingly, it is required to maintain durability even when the head-up display is maintained and/or driven in a much harsher condition than before, for example, at a very high temperature, and to realize clear image quality without noise caused by reflection of external light. .

The present application provides a cover dust stack having excellent high-temperature durability and capable of realizing clear image quality, and a head-up display including the same.

Among the physical properties mentioned in the present specification, the physical properties in which the measurement temperature and/or the measurement pressure affect the result are the results measured at room temperature and/or atmospheric pressure, unless specifically stated otherwise.

The term room temperature is a natural temperature that is warmed or not reduced to a temperature, and means, for example, any temperature within the range of 10°C to 30°C, about 23°C or about 25°C. In addition, the unit of temperature in this specification is °C unless otherwise specified.

The term atmospheric pressure is a natural pressure that is not pressurized or depressurized, and usually means about 1 atmosphere of atmospheric pressure.

In the case of a property in which the measured humidity affects the result in the present specification, the property is a property measured at natural humidity that is not specifically controlled at the room temperature and/or atmospheric pressure.

In the present specification, the term downward direction refers to a direction from the protective substrate of the cover dust stack toward the absorption type polarizer, and the term upward direction refers to a direction opposite to this, and refers to a direction from the absorption type polarizer toward the protective substrate.

The present application relates to a cover dust laminate including an absorption type polarizer. The term cover dust stack is located on the path of the external light incident on the image generating device in the head-up display and the path of the optical signal emitted from the image generating device, so that at least a portion of the external light is introduced into the image generating device. It refers to an optical laminate that is present so as to block and transmit the light signal emitted from the image generating device. In addition, in the present application, the term polarizer may refer to, for example, a device or film exhibiting a polarization function.

If the polarizer applied in the present application is an absorption type polarizer, the specific type is not limited. In the above, the absorption type polarizer may be, for example, an absorption type linear polarizer. The term absorption type linear polarizer transmits linear polarized light vibrating in one direction from incident light vibrating in several directions, and absorbs light vibrating in the other direction, for example, polarized light in a direction perpendicular to the transmitted linear polarized light. It may mean a device having a function to allow.

The most common absorption type linear polarizer known is a so-called poly(vinylalcohol) polarizer (hereinafter referred to as PVA). In the present specification, the term PVA is meant to include polyvinyl alcohol and/or derivatives thereof, unless otherwise specified. PVA polarizers include, for example, stretched PVA films in which anisotropic absorbing substances such as iodine and dichroic dyes are adsorbed and oriented, or so-called coated PVA polarizers, such as polarizers formed thin by applying PVA to a coating method. Although known, in the present application, all of the above types of polarizers may be applied.

The polarizer applied in the embodiment of the present application is a PVA polarizer, and this polarizer is usually manufactured by applying a dyeing and stretching process to a PVA original film. In the manufacturing process of the PVA polarizer, if necessary, additional processes such as swelling, crosslinking, washing and/or complementary color processes may be performed, and a process of manufacturing a PVA polarizer through such a process is known.

The thickness of the absorption type polarizer may be in the range of 5 μm to 50 μm, in one example. In other examples, 6 μm or more, 7 μm or more, 8 μm or more, 9 μm or more, 10 μm or more, 11 μm or more, 12 μm or more, 13 μm or more, 14 μm or more, 15 μm or more, 16 μm or more, 17 μm Or more, 18 μm or more, 19 μm or more, 20 μm or more, 21 μm or more, 22 μm or more, 23 μm or more, 24 μm or more, 45 μm or less, 40 μm or less, 35 μm or less, 30 μm or less, 29 μm or less, 28 μm or less, 27 μm or less, 26 μm or less, 25 μm or less, 24 μm or less, 23 μm or less, 22 μm or less, 21 μm or less, 20 μm or less, 19 μm or less, 18 μm or less, 17 μm or less, 16 μm Hereinafter, it may be 15 μm or less, 14 μm or less, 13 μm or less, or 12 μm or less, but is not limited thereto.

In one example, in order to ensure durability of the cover dust laminate, particularly high temperature reliability, as the polarizer, a PVA polarizer containing a zinc component may be used. In the above, examples of the zinc component include zinc and/or zinc ions. The PVA polarizer may also contain a potassium component such as potassium or potassium ions as an additional component. Using a polarizer containing such a component can provide a cover dust laminate that stably maintains durability even under high temperature conditions.

The content of the zinc component may be further adjusted. The content of the zinc (Zn) component included in the PVA polarizer may be in the range of 500mg/kg to 1000mg/kg in one example. In other examples, the content is 550 mg/kg or more, 600 mg/kg or more, 650 mg/kg or more, 700 mg/kg or more, 710 mg/kg or more, 720 mg/kg or more, 730 mg/kg or more, 740 mg /kg or more, 750 mg/kg or more, 760 mg/kg or more, 770 mg/kg or more, 780 mg/kg or more, 790 mg/kg or more or 800 mg/kg or more, 990 mg/kg or less, 980 mg/ kg or less, 970 mg/kg or less, 960 mg/kg or less, 950 mg/kg or less, 940 mg/kg or less, 930 mg/kg or less, 920 mg/kg or less, or 910 mg/kg or less. The content of the zinc (Zn) component is obtained by measuring the weight (mg) of the zinc (Zn) component contained therein based on the weight of 1 kg of the PVA polarizer.

The content of the potassium component included in the PVA polarizer may be 0.35% by weight to 0.7% by weight. In other examples, the content of the potassium (K) component is 0.36 wt% or more, 0.37 wt% or more, 0.38 wt% or more, 0.39 wt% or more, 0.40 wt% or more, 0.41 wt% or more, 0.42 wt% or more, 0.43 wt% Or more, 0.44% by weight or more, 0.45% by weight or more, 0.46% by weight or more, 0.47% by weight or more, 0.48% by weight or more, or 0.49% by weight or more, or 0.69% by weight or less, 0.68% by weight or less, 0.67% by weight or less, 0.66% by weight % Or less, 0.65 wt% or less, 0.64 wt% or less, 0.63 wt% or less, 0.62 wt% or less, 0.61 wt% or less, 0.60 wt% or less, 0.59 wt% or less, 0.58 wt% or less, 0.57 wt% or less, 0.56 wt% % Or less, 0.55 wt% or less, 0.54 wt% or less, 0.53 wt% or less, 0.52 wt% or less, 0.51 wt% or less, 0.5 wt% or less, or 0.49 wt% or less. The content of the potassium (K) component is expressed as a percentage by weight of the potassium (K) component contained therein to 100 parts by weight of the PVA polarizer.

In the above description, the content of zinc and/or potassium components can be measured in the following manner. First, dissolve 0.1g of polarizer in 2mL of aqueous nitric acid solution having a concentration of about 65% by weight at room temperature, and then dilute to 40mL with deionized water, and then use ICP-OES (Optima 5300) to zinc (Zn) contained in the polarizer. The weight of and potassium (K) can be measured, respectively.

Since the cover dust laminate including a polarizer containing zinc and/or potassium in the above range has excellent resistance to redundancy, a change in transmittance is also minimized or not changed.

For example, a cover dust laminate containing zinc (Zn) and potassium (K) in the weight range as described above in a polarizer has a change in single transmittance according to Equation 1 below (ΔT _s ) after a heat resistance test The absolute value of may be 10% or less. In the present specification, the term single transmittance means an average of the transmittance of the absorption axis and the transmittance of the transmission axis. In the above, the single transmittance may be a result of measuring light in the visible region, for example, light in the range of approximately 380 nm to 780 nm using a JASCO V-7100 spectrophotometer.

[Equation 1]

△T _s = T _a -T _i

In Equation 1, ΔT _s is an amount of change in single transmittance, T _a is _a single transmittance after _a heat resistance test, and T _i may be an initial single transmittance before a heat resistance test.

In the above, the heat resistance test may mean a test in which the cover dust stack is maintained at about 110 °C for about 1000 hours.

In other examples, the absolute value of the single transmittance change amount (△T _s ) is 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4.9% or less, 4.8% or less, 4.7% or less, 4.6% Less than, 4.5% or less, 4.4% or less, 4.3% or less, 4.2% or less, 4.1% or less, 4% or less, 3.9% or less, 3.8% or less, 3.7% or less, 3.6% or less, 3.5% or less, 3.4% or less, 3.3% or less, 3.2% or less, 3.1% or less, 3% or less, 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% Or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less or 0%, or 1% or more, 1.5% or more, 2.0% or more, 2.5% or more, or 3.0% It can be more than that. Ideally, since no change in the transmittance means that there is no redness, preferably, the absolute value of the change amount ΔT _s may be 0%, and in other examples, it may be greater than about 0%.

In addition, the cover dust laminate containing zinc and/or potassium in the above range may have optically controlled properties. For example, the cover dust laminate may satisfy Equations 2 and/or 3 below.

[Equation 2]

-b/a = 2.3 to 3.5:

[Equation 3]

0 <1000 × (y-x) ≤ 3

In Equations 2 and/or 3, b is the b value of the CIE color space of the cover dust stack, a is the a value of the CIE color space of the cover dust stack, and x is the CIE color space of the cover dust stack. Is the X value, and y may be the Y value of the CIE color space of the cover dust stack.

In this specification, the terms color coordinates a and b may mean coordinates a and b in an INTERNATIONAL COMMISSION OF ILLUMINATION (CIE) Lab color space. As the color is biased toward green, a value of a may represent a negative number, and as the color is biased toward red or purple, the value a may represent a positive number. In addition, the b value may be negative as it is biased toward blue, and the b value may be positive as it is biased toward yellow.

In the present specification, the terms X, Y, and Z are tristimulus values, and may be colors similar to red, green, and blue, respectively. The values of x and y are values calculated from X, Y, and Z, and may be expressed as Equation 4 below, and may be an index representing chromaticity. A smaller difference between x and y derived by Equation 4 below indicates a chromaticity close to neutral white, and a larger difference between x and y may indicate that a specific color may be biased.

[Equation 4]

x = X/(X+Y+Z)

y = Y/(X+Y+Z)

In the present application, the polarizer may have a ratio (-b/a) of the -a value in Equation 2 and the b value to be about 2.3 or more and 3.5 or less. In other examples, 2.4 or more, 2.5 or more, 2.6 or more, 2.7 or more, 2.8 or more, 2.81 or more, 2.82 or more, 2.83 or more, 2.84 or more, 2.85 or more, 2.86 or more, 2.87 or more, 2.88 or more, 2.89 or more, 2.90 or more, 2.91 or more Or 2.92 or more, 3.49 or less, 3.48 or less, 3.47 or less, 3.46 or less, 3.45 or less, 3.44 or less, 3.43 or less, 3.42 or less, 3.41 or less, 3.40 or less, 3.39 or less, 3.38 or less, 3.37 or less, 3.36 or less, 3.35 or less, 3.34 or less, 3.33 or less, 3.32 or less, 3.31 or less, 3.30 or less, 3.29 or less, 3.28 or less, 3.27 or less, 3.26 or less, 3.25 or less, 3.24 or less, 3.23 or less, 3.22 or less, 3.21 or less, 3.20 or less, 3.19 or less, 3.18 or less , 3.17 or less, 3.16 or less, 3.15 or less, 3.14 or less, 3.13 or less, 3.12 or less, 3.11 or less, 3.10 or less, 3.09 or less, 3.08 or less, 3.07 or less, 3.06 or less, 3.05 or less, 3.04 or less, 3.03 or less, 3.02 or less, 3.01 It may be 3.00 or less, 2.99 or less, 2.98 or less, 2.97 or less, 2.96 or less, 2.95 or less, 2.94 or less, 2.93 or less, 2.92 or less, 2.91 or less, or 2.9 or less.

By controlling the range of the -b/a value of Equation 2 as described above, the so-called redness phenomenon is not caused even when driving and/or maintaining under very severe conditions without yellowish or blueish. It is possible to provide a cover dust laminate that is not covered, and the cover dust laminate may be applied to a head-up display to provide a head-up display capable of realizing clear image quality.

In the present application, the polarizer may have a value of 1000 × (y-x) in Equation 3 above about 0 and 3 or less. In other examples, the above value is greater than 0.1, greater than 0.2, greater than 0.3, greater than 0.4, greater than 0.5, greater than 0.6, greater than 0.7, greater than 0.8 or greater than 0.9, or less than 2.9, less than 2.8, less than 2.7, less than 2.6, less than 2.5, less than 2.4 , 2.3 or less, 2.2 or less, 2.1 or less, 2 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, or 1.0 or less. By controlling the value of 1000 × (y-x) in Equation 3 in the above range, it is possible to provide a head-up display capable of realizing clear image quality without being biased to a specific color.

When the light emitted from the image generating device passes through the cover dust stack that satisfies Equation 2 and/or 3 above to form a screen, it is possible to implement a neutral white or black visual sensation, thereby providing clearer image quality. It can provide the desired effect, such as can.

When the cover dust laminate of the present application has the above properties, it is possible to prevent, reduce, alleviate, suppress and/or delay redness, even when driven or maintained under very harsh conditions (for example, very high temperature conditions). It is possible to provide a cover dust stack that does not cause a so-called redundancy phenomenon, and the cover dust stack is applied to a head-up display, so that redundancy of internal components such as an image generating device can be prevented.

The cover dust laminate of the present application may not include a reflective polarizer. The term reflective polarizer may refer to a device having a function of transmitting one polarized light and reflecting the other polarized light from incident light vibrating in various directions. The reflective polarizer may include, for example, a Dual Brightness Enhancement Film (DBEF), a lyotropic liquid crystal (LLC layer), or a wire grid polarizer.

Since the cover dust stacked body including the reflective polarizer reflects light vibrating in a specific direction to the outside, it may play a role of blocking external light, but especially when applied to a vehicle head-up display, which will be described later, reflective There may be a problem that it is difficult to realize clear image quality because the generated light enters the driver's field of view.

Accordingly, the cover dust stack of the present application may be a cover dust stack that includes an absorption type polarizer but does not include a reflective polarizer, thereby implementing a clear image quality.

However, since the absorption type polarizer is particularly vulnerable to high temperatures, high temperature durability may be a problem when an absorption type polarizer other than a reflective type polarizer, such as the cover dust laminate of the present application, is applied.

Accordingly, the cover dust laminate of the present application may provide a cover dust laminate having excellent high temperature durability by including a polyvinyl alcohol absorption polarizer containing zinc and/or potassium within a predetermined range as described above. In addition, by asymmetrically designing the upper protective layer and/or the moisture permeability between the protective substrate and the lower protective layer to be described later, it is possible to provide a cover dust laminate having excellent high-temperature durability while realizing clear image quality.

The present application may be a cover dust stack in which a protective substrate is attached to an upper direction of the absorption type polarizer. In the present specification, the term protective substrate may mean a layer having a surface pencil hardness of 0.5H or more. The pencil hardness may be measured by drawing a pencil lead on the surface of the protective substrate at an angle of 45 degrees and a load of 500 g at a temperature of about 25° C. and a relative humidity of 50% using a general pencil hardness measuring equipment. Pencil hardness can be measured by increasing the hardness of the pencil lead step by step until occurrence of defects such as indentations, scratches, or ruptures on the surface of the protective substrate is confirmed. In other examples, the pencil hardness of the protective substrate is about 0.6H or more, 0.7H or more, 0.8H or more, 0.9H or more, 1H or more, 2H or more, 3H or more, 4H or more, 10H or less, 9H or less, 8H or less, 7H or less, It may be 6H or less, 5H or less, 4H or less, 3H or less, or 2H or less.

The protective substrate is not limited as long as it has a surface pencil hardness in the above range, and may be, for example, a glass substrate, a polymer film having a hard coating layer formed in the upper direction, and the hard coating layer may be made of a known material. have.

The polymer film is, for example, a polycarbonate resin film, a polyolefin resin film such as a cyclic polyolefin resin film having a cyclo-based or norbornene structure, a cellulose resin film such as triacetyl cellulose, a polyethylene terephthalate or polyethylene naphthalate, etc. Polyester resin film, polyethersulfone resin film, polysulfone resin film, polyamide resin film, polyimide resin film, (meth)acrylic resin film, polystyrene resin film or polyvinyl alcohol resin film.

The thickness of the protective substrate may be, for example, in the range of 50 μm to 1200 μm. In other examples, 100 μm or more, 150 μm or more, 200 μm or more, 250 μm or more, 300 μm or more, 350 μm or more, 400 μm or more, 450 μm or more, 500 μm or more, 550 μm or more, 600 μm or more, 650 μm Or more, 700 μm or more, 750 μm or more, 800 μm or more, 850 μm or more, 900 μm or more, 950 μm or more, 1150 μm or less, 1100 μm or less, 1050 μm or less, 1000 μm or less, 950 μm or less, 900 μm or less, 850 μm or less, 800 μm or less, 750 μm or less, 700 μm or less, 650 μm or less, 600 μm or less, 550 μm or less, 500 μm or less, 450 μm or less, 400 μm or less, 350 μm or less, 300 μm or less, 250 μm Hereinafter, it may be 200 μm or less, 150 μm or less, or 100 μm or less, but is not limited thereto.

By attaching the protective substrate as described above to the upper direction of the polarizer, the cover dust laminate can be protected from external impact.

The cover dust stack of the present application may further include, for example, a protective layer (hereinafter referred to as a lower protective layer) in the lower direction of the polarizer. As the lower protective layer, a film having excellent transparency, mechanical strength, and thermal stability may be used.

Examples of such films include polyolefin resin films such as cyclic polyolefin resins having a cyclo-based or norbornene structure, cellulose resin films such as triacetylcellulose, polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, and polyethers. And a sulfone resin film, a polysulfone resin film, a polycarbonate resin film, a polyamide resin film, a polyimide resin film, a (meth)acrylic resin film, a polystyrene resin film or a polyvinyl alcohol resin film.

The thickness of the lower protective layer may be in the range of 10 μm to 90 μm, in one example. In another example, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, 60 μm or more, 80 μm or less, 75 μm It may be less than or equal to 70 μm, less than 65 μm, less than 60 μm, or less than 55 μm, but is not limited thereto.

When the moisture permeability of the lower protective layer is low, moisture in the polarizer may not be properly discharged to the outside, and thus a problem in that the polarizer is redundant may be caused, so that the lower protective layer constituting the cover dust stack of the present application has a high moisture permeability. It may be desirable to have.

In the present application, the moisture permeability of the lower protective layer may be 1g/(100in ² ×day) or more in an example. In the above, the term moisture permeability may mean the weight of water vapor passing through the protective layer having an area of 100 in ² for 1 day (24 hours) under a specified temperature and humidity, and a moisture permeability tester (Labthink, W3/0120) The moisture permeability of the protective layer can be measured under the conditions described later.

If the moisture permeability of the lower protective layer is less than 1g/(100in ² ×day), moisture in the polarizer cannot be properly discharged to the outside, which may cause a problem in that the polarizer is redundant, so that the cover dust stack of the present application The lower protective layer constituting may preferably have a moisture permeability of 1g/(100in ² ×day) or more.

More specifically, since the PVA polarizer is generally highly hydrophilic, it is very difficult to completely control moisture in a process of laminating a protective substrate and/or a protective layer. On the other hand, PVA polarizer reacts, for example, KI ₅ contained in PVA polarizer by moisture in a high temperature/high humidity environment is decomposed into I ₂ and KI ₃ and/or KI ₃ is decomposed into I ₂ and I. As this happens, polarization may be broken and redness may be caused.

Therefore, among the above examples, a cellulose resin film such as a triacetyl cellulose film having a relatively high moisture permeability, a polycarbonate resin film, a (meth)acrylic resin film, a polyester resin film, and the like may be more preferable.

The cover dust layered body of the present application applies a lower protective layer of 1 g/(100 in ² × day) or more in the lower direction of the PVA polarizer to allow moisture in the PVA polarizer to be discharged to the outside under high temperature. Can be prevented.

The upper limit of the moisture permeability of the lower protective layer is not particularly limited, but in one example, when considering the possibility of moisture entering the polarizer from the outside, it may be preferably 100 g/(100in ² ×day) or less.

In another example, the moisture permeability of the lower protective layer is 2 g/(100in ² ×day) or more, 3 g/(100in ² ×day) or more, 4 g/(100in ² ×day) or more, 5 g/(100in ² ×day) or more, 5.1 g/(100in ² ×day) or more, 5.2 g/(100in ² ×day) or more, 5.3 g/(100in ² ×day) or more, 5.4 g/(100in ² ×day) or more, 5.5 g/(100in ² ×day) or more, 5.6 g/(100in ² ×day) or more, 5.7 g/(100in ² ×day) or more, 5.8 g/(100in ² ×day) or more, 5.9 g/(100in ² ×day) day) or more or 6.0 g/(100in ² ×day) or more or 90 g/(100in ² ×day) or less, 80 g/(100in ² ×day) or less, 70 g/(100in ² ×day) or less, 60 g /(100in ² ×day) or less, 50 g/(100in ² ×day) or less, 40 g/(100in ² ×day) or less, 30 g/(100in ² ×day) or less, 20 g/(100in ² ×day) ) Or less, 10 g/(100in ² ×day) or less, 9.0 g/(100in ² ×day) or less, or 8.0 g/(100in ² ×day) or less.

The cover dust laminate of the present application has excellent high-temperature durability, such as being able to provide clear image quality even when maintained and/or driven at high temperatures when applied to a head-up display by applying the lower protective layer having high moisture permeability as described above. Can have

In another example, the present application may be a cover dust stack 100 further including an upper protective layer 121 between the protective substrate 130 and the absorption polarizer 110 as shown in FIG. 3. As the upper protective layer, a resin film or a liquid crystal layer having excellent transparency, mechanical strength, and thermal stability may be used.

Examples of the film include a polyolefin resin film such as a cyclic polyolefin resin having a cyclo-based or norbornene structure, a cellulose resin film such as triacetylcellulose, a polyester resin film such as polyethylene terephthalate or polyethylene naphthalate, and polyether. And a sulfone resin film, a polysulfone resin film, a polycarbonate resin film, a polyamide resin film, a polyimide resin film, a (meth)acrylic resin film, a polystyrene resin film or a polyvinyl alcohol resin film.

In one example, the thickness of the upper protective layer may be in the range of 10 μm to 90 μm. In another example, 15 μm or more, 20 μm or more, 25 μm or more, 30 μm or more, 35 μm or more, 40 μm or more, 45 μm or more, 50 μm or more, 55 μm or more, 60 μm or more, 80 μm or less, 75 μm It may be less than or equal to 70 μm, less than 65 μm, less than 60 μm, or less than 55 μm, but is not limited thereto.

In an example, the upper protective layer of the present application may be a retardation layer having an in-plane retardation. In the present specification, the retardation layer is an optically anisotropic layer, and may mean a device capable of converting incident polarization by controlling birefringence. The phase difference layer may have a 1/4 wavelength phase delay characteristic or a 1/2 wavelength phase delay characteristic. In the present specification, the n-wavelength phase delay characteristic may mean a characteristic capable of phase delaying incident light by n times the wavelength of the incident light within at least a partial wavelength range. Accordingly, the 1/4 wavelength phase delay characteristic may mean a characteristic capable of phase delaying incident light by 1/4 times the wavelength of the incident light within at least a partial wavelength range, and the 1/2 wavelength phase delay The characteristic may mean a characteristic capable of retarding the incident light by 1/2 times the wavelength of the incident light within at least a partial wavelength range.

As the upper protective layer as the retardation layer, a polymer layer or a liquid crystal layer may be applied. As the polymer layer, for example, a cyclic polyolefin resin having a cyclo-based or norbornene structure described above, a cellulose resin such as triacetylcellulose, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, and polyethersulfone Resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth)acrylic resin, polystyrene resin or polyvinyl alcohol resin are stretched or contracted under appropriate conditions to provide birefringence. Can be used. The liquid crystal layer may include a film in which liquid crystal molecules are aligned and polymerized. The liquid crystal molecule may be a polymerizable liquid crystal molecule. In the present specification, a polymerizable liquid crystal molecule may refer to a molecule including a site capable of showing liquid crystallinity, for example, a mesogen skeleton, and including one or more polymerizable functional groups. In addition, the inclusion of the polymerizable liquid crystal molecules in a polymerized form may mean a state in which the liquid crystal molecules are polymerized to form a skeleton such as a main chain or side chain of a liquid crystal polymer in a liquid crystal film.

In the present specification, the term in-plane phase difference (R _in ) is calculated by Equation 5 below.

[Equation 5]

R _in = d × (n _x -n _y )

In Equation 5, R _in is an in-plane retardation, d is the thickness of the upper protective layer, and n _x and n _y are refractive indices in the x-axis and y-axis directions, respectively. In the present specification, the terms x-axis and y-axis mean a direction parallel to the in-plane slow axis of the upper protective layer, and the y-axis means a direction parallel to the in-plane fast axis of the upper protective layer, unless otherwise noted, , The x-axis and y-axis may be orthogonal to each other in a plane.

In the present application, the in-plane retardation (R _in ) of the upper protective layer with respect to light having a wavelength of 550 nm may be, for example, 100 nm or more and 400 nm or less, and in other examples, 110 nm or more, 120 nm or more, 130 nm or more, 140 nm or more, 150 nm or more, 160nm or more, 170nm or more, 180nm or more, 190nm or more, 200nm or more, 210nm or more, 220nm or more, 230nm or more, 240nm or more, 250nm or more, 260nm or more, 270nm or more, 280nm or more, 290nm or more, 300nm or more, 310nm or more, 320nm or more , 330nm or more, 340nm or more, 350nm or more, 360nm or more, 370nm or more, 380nm or more, 390nm or more, 390nm or less, 380nm or less, 370nm or less, 360nm or less, 350nm or less, 340nm or less, 330nm or less, 320nm or less, 310nm or less, 300nm Or less, 290nm or less, 280nm or less, 270nm or less, 260nm or less, 250nm or less, 240nm or less, 230nm or less, 220nm or less, 210nm or less, 200nm or less, 190nm or less, 180nm or less, 170nm or less, 160nm or less, 150nm or less, 140nm or less, 130nm or less, 120nm or less, 110nm or less, 100nm or less, 90nm or less, 80nm or less, 70nm or less, 60nm or less, 50nm or less, 40nm or less, 30nm or less, 20nm or less, 10nm or less, or 0nm, but is not limited thereto.

The cover dust laminate of the present application may not include an adhesive layer, an adhesive layer, and/or a release film on the outermost layer in the lower direction of the absorption type polarizer.

Conventionally, a polarizing plate in which a layer having low moisture permeability is disposed on one side of the absorption type polarizer and a layer having high moisture permeability is disposed on the other side has existed. However, by having a structure in which a pressure-sensitive adhesive layer, an adhesive layer and/or a release film, etc. exist on the outermost layer of the surface on which the layer having high moisture permeability is disposed, in the end, for example, the polarizing plate is applied to other members such as an image generating device. It was attached to the closed structure to prevent the inflow and outflow of moisture through both sides of the polarizer.

Unlike the conventional polarizing plate as described above, the cover dust laminate of the present application has a high moisture permeability, for example, a lower protective layer having a moisture permeability of 1 g/(100 in ² × day) or more in the lower direction of the absorption type polarizer. , It may have a structure in which the pressure-sensitive adhesive layer, the adhesive layer and/or the release film do not exist in the outermost layer in the lower direction of the absorption polarizer. That is, the cover dust laminate of the present application may not include a layer having a moisture permeability of less than 1 g/(100 in ² × day) in the lower direction of the absorption polarizer.

Since the cover dust laminate of the present application has the structure as described above, it may be easy to discharge moisture in a downward direction of the absorption type polarizer, particularly in a high temperature environment. Accordingly, when applied to a head-up display to be described later, even when driving and/or maintenance is performed at a high temperature, a clear image quality can be realized without redundancy, and a cover dust laminate having excellent high temperature durability can be provided.

The cover dust laminate of the present application may have various types of structures. For example, FIG. 2 shows that in the most basic structure of the cover dust stack 100, the protective substrate 130 is formed in the upper direction of the absorption polarizer 110, and the lower protective layer 122 is formed in the lower direction of the polarizer. This shows the formed structure. However, the protective layer may be formed on one or both sides of the polarizer, for example, the structure in which the upper protective layer 121 is introduced between the protective substrate 130 and the absorption type polarizer 110 as shown in FIG. Can be indicated.

The structures of FIGS. 2 and 3 are an example of the present application, and the cover dust stack of the present application may be configured in various other structures.

The present application also relates to a Head Up Display comprising the cover dust stack. The head-up display includes an image generating device; And a cover dust stacked body, wherein the image generating device comprises: the image generating device so that an image emitted from the image generating device passes through the cover dust stacked body; And a head-up display on which a cover dust stack is disposed.

In the present application, the image generating device may be an image generating device that emits an image in a linearly polarized state. When using, for example, a liquid crystal display (LCD) or an organic light emitting diode (OLED) as the image generating device, by attaching a polarizing film to the image generating device, the emitted light signal is in a linearly polarized form having a constant polarization direction. Can be made, and through this, the signal loss of optical signals transmitted to various parts can be minimized.

In the present application, the smaller of the angle between the vibration direction of linearly polarized light emitted from the image generating device and incident on the cover dust stack and the absorption axis of the polarizer of the cover dust stack is, for example, 50 degrees to 80 degrees. It may be a head-up display 10 in which the image generating device 20 and the cover dust stack 100 are disposed so as to fall within a range of degrees.

The angle is based on a position at which the minimum luminance is measured when the luminance of light transmitted through the cover dust stack 100 is measured while rotating the cover dust stack 100 in the head-up display 10. °), it may be an angle measured in a clockwise or counterclockwise direction.

In another example, the angle is 51 degrees or more, 52 degrees or more, 53 degrees or more, 54 degrees or more, 55 degrees or more, 56 degrees or more, 57 degrees or more, 58 degrees or more, 59 degrees or more, or 60 degrees or more, or 79 degrees. Below, it may be 78 degrees or less, 77 degrees or less, 76 degrees or less, 75 degrees or less, 74 degrees or less, 73 degrees or less, 72 degrees or less, 71 degrees or less, or 70 degrees or less.

In the present application, the head-up display may further include a light control means. In the present specification, the term light control means is a device for directing an optical signal emitted from an image generating device to a windshield where an image is displayed after passing through the cover dust stack, for example, a reflector and/or a beam splitter. I can.

In one example, the head-up display 10 includes an image generating device 20 and the cover dust stack 100 as shown in FIG. 4, and the emitted light 200 from the image generating device is a beam splitter 30 ) While passing through, some of the emitted light becomes the reflected light 202 reflected in the direction of the reflector 40, and the other part becomes the transmitted transmitted light 201 and passes through the cover dust stack 100 It may be a head-up display that can implement two independent screens on the shield 50. In this specification, the term beam splitter refers to a device that divides one light source into two light sources, and therefore, when one light source passes through the beam splitter, some are transmitted and the other are reflected along two different light paths. I can move.

As described above, the head-up display of the present application may implement two independent screens in an example. The two independent screens may be implemented in contact with each other, and therefore, it may be required that there is little difference in luminance between the two screens. The present application provides a clear image quality with little difference in luminance between two independent screens by arranging the angle formed by the polarization direction of the linearly polarized light emitted from the image generating device and the absorption axis of the polarizer of the cover dust stack as described above. Head-up display can be implemented.

In this specification, the term luminance refers to the light density in a specific direction, that is, the amount of light that passes through a certain area and enters at a certain solid angle, and'there is almost no difference in luminance' refers to the luminance of two independent screens. This means not only the same case, but also the case where the ratio of the luminance is 0.5 to 1.5 or less. In another example, the ratio may be 0.52 or more, 0.54 or more, 0.56 or more, 0.58 or more, 0.60 or more, 0.62 or more, 0.64 or more, 0.66 or more, or 0.67 or more, or 1.45 or less, 1.4 or less, 1.35 or less, or 1.3 or less. When the luminance ratio of two independent screens satisfies the above range, for example, the driver may recognize the two independent screens as one screen.

The present application includes a cover dust stack having the above-described characteristics, and by controlling the angle formed by the vibration direction of linearly polarized light emitted from the image generating device and the absorption axis of the polarizer of the cover dust stack in the above range, high temperature, etc. Even under severe conditions, redness is not caused, clear image quality can be realized, and when two independent screens are displayed, a head-up display with an appropriate luminance ratio of each screen can be provided.

In the present application, it is possible to provide a cover dust stack that does not cause a so-called redundancy phenomenon even when driven or maintained under very severe conditions (eg, very high temperature conditions). In addition, the cover dust stack is applied to the head-up display, preventing redundancy of internal parts such as an image generating device, while realizing clear image quality, and when displaying two independent screens, the luminance ratio of each screen is appropriate. It can provide a head-up display.

1 is a diagram for explaining a typical structure of a head-up display.
2 and 3 are diagrams for explaining an exemplary structure of the cover dust laminate of the present application.
4 is a diagram for describing an exemplary structure of a head-up display capable of implementing two independent screens.

Hereinafter, the cover dust stack, etc. will be described in more detail through examples according to the present application, but the scope of the present application is not limited to the following.

In the following, each physical property of the cover dust laminated body was measured in the following manner.

1.Weight measurement of zinc (Zn) and potassium (K) in the polarizer

The weight of zinc (Zn) and potassium (K) in the polarizer is measured in the following way.

Was. First, dissolve 0.1 g of polarizer in an aqueous nitric acid solution (2 mL) having a concentration of about 65% by weight at room temperature (about 25°C), and then dilute it to 40 mL with deionized water, and then use ICP-OES (Optima 5300) equipment. The weights of potassium (K) and zinc (Zn) contained in the polarizer were measured, respectively.

2. CIE color coordinate measurement

Color coordinates were measured using a JASCO V-7100 Spectrophotometer. The JASCO V-7100 spectrophotometer rotates the absorption axis of the polarizing plate to be measured from 0 degrees to 360 degrees with respect to the absorption axis of the polarizer built into the device, and then measures the color coordinate (TD color coordinate) at the point where the transmittance is minimum. , After measuring the color coordinate (MD color coordinate) by rotating the absorption axis of the polarizing plate to be measured by 90 degrees clockwise at the point where the transmittance is minimum, it is a device that derives a representative value of the color coordinate based on each measured value. The color coordinates described in the examples of this specification are the color coordinates identified by the JASCO V-7100 spectrophotometer.

3. Single transmittance measurement

The single transmittance of the cover dust laminate was measured using a JASCO V-7100 Spectrophotometer. The JASCO V-7100 spectrophotometer is a device that measures the single transmittance of the cover dust laminate within a range of 380 to 780 nm and derives a representative value for the wavelength range.In this embodiment, The single transmittance confirmed by the JASCO V-7100 Spectrophotometer is described.

4. Luminance measurement

Cover dust stack 100, image generator (LGE, LA080WV5) (20), beam splitter (Edmund, B-plate Beamsplitter) (30), reflector (Edmund, S-mirror) (40), wind The shield 50 was arranged as shown in FIG. 4, and the angle of the cover dust stack was changed, and the luminance of the screen displayed on the windshield 50 was measured. When measuring, the luminance of the screen formed by the reflected light 202 and the screen formed by the transmitted light 201 is measured using a two-dimensional luminance measuring device (Risa company, Color One) at a location 50cm away from the windshield 50. I did.

Preparation Example 1. Preparation of polarizer (A)

PVA (poly(vinyl alcohol)) film (Japan Synthetic Company, M3000 grade) having a thickness of about 30 μm was added to a dyeing solution at 28° C. containing 0.3% by weight of iodine (I ₂ ) and 3.0% by weight of potassium iodide (KI). Dyeing was performed by immersing for 60 seconds. Subsequently, the dyed PVA film was crosslinked by immersing in an aqueous solution (crosslinking solution) of 35° C. containing 1% by weight of boron and 3% by weight of potassium iodide (KI) for 60 seconds. Thereafter, the crosslinked PVA film was stretched at a draw ratio of 5.4 times using an inter-roll stretching method. The stretched PVA film was washed by immersing in ion-exchanged water at 25° C. for 60 seconds, and immersed in an aqueous solution at 25° C. containing 2.5% by weight of zinc nitrate and 3% by weight of potassium iodide (KI) for 30 seconds. Thereafter, the PVA film was dried at 80° C. for 60 seconds to prepare a PVA polarizer. The resulting polarizer had a final thickness of about 12 μm, potassium content of about 0.49 wt%, and zinc content of about 910 mg/kg.

Preparation Example 2. Preparation of polarizer (B)

Prepared except that the stretched PVA film was immersed in ion-exchanged water at 25° C. for 60 seconds to wash, and immersed in an aqueous solution at 25° C. containing 2.5 wt% zinc nitrate and 5 wt% potassium iodide (KI) for 30 seconds It was prepared in the same manner as in Example 1. The resulting polarizer had a final thickness of about 12 μm, a potassium content of about 0.55% by weight, and a zinc content of about 740 mg/kg.

Preparation Example 3. Preparation of polarizer (C)

Prepared except that the stretched PVA film was immersed in ion-exchanged water at 25° C. for 60 seconds to wash, and immersed in an aqueous solution at 25° C. containing 2.5 wt% zinc nitrate and 1 wt% potassium iodide (KI) for 30 seconds It was prepared in the same manner as in Example 1. The resulting polarizer had a final thickness of about 12 μm, potassium content of about 0.29 wt%, and zinc content of about 900 mg/kg.

Preparation Example 4. Preparation of polarizer (D)

Prepared except that the stretched PVA film was immersed in ion-exchanged water at 25° C. for 60 seconds to wash, and immersed in an aqueous solution at 25° C. containing 3.5 wt% zinc nitrate and 5 wt% potassium iodide (KI) for 30 seconds It was prepared in the same manner as in Example 1. The resulting polarizer had a final thickness of about 12 μm, a potassium content of about 0.59% by weight, and a zinc content of about 1030 mg/kg.

Manufacturing Example 5. Preparation of polarizer (E)

Prepared except that the stretched PVA film was immersed in ion-exchanged water at 25° C. for 60 seconds to wash, and immersed in an aqueous solution at 25° C. containing 4.5 wt% zinc nitrate and 5 wt% potassium iodide (KI) for 30 seconds It was prepared in the same manner as in Example 1. The prepared polarizer had a final thickness of about 12 μm, a potassium content of about 0.53% by weight, and a zinc content of about 1160 mg/kg.

Preparation Example 6. Preparation of the material for the internalization layer (A')

TMPTA (trimethylolpropane triacrylate) was applied as a binder, and hollow silica particles were applied to prepare an internal layer. As the hollow silica particles, particles having D10, D50 and D90 particle diameters of 32.1 nm, 62.6 nm and 123.4 nm, respectively, were used. In this case, after forming the internalization layer, the average of the pore sizes measured by TEM was about 38.3 nm, and the particle diameter was about 53 nm. The binder, the hollow silica particles, a fluorinated compound (RS-90, DIC) and an initiator (Irgacure 127, Ciba) were used in a weight ratio of 31:65:0.1:3.9 based on solid content (binder: hollow silica particles: contained A fluorine compound: initiator) was diluted in MIBK (methyl isobutyl ketone) as a solvent to prepare a coating solution.

Example 1.

A cycloolefin polymer film (Zeon) having a thickness of about 30 μm was attached to the polarizer (A) obtained in Preparation Example 1 by applying a general optical water-based adhesive layer (thickness: 100 nm). Separately, an internal layer was formed on a triacetylcellulose film (Hyosung) having a thickness of about 60 μm. The fire resistant layer was coated with the material of the fire resistant layer (A') of Preparation Example 6 on the triacetylcellulose film with a Mayer bar, dried at about 60° C. for about 1 minute, and then irradiated with ultraviolet rays (252 mJ/cm ² ) to give a final thickness Was formed to be about 450 nm. Subsequently, the laminate of the triacetyl cellulose film in which the anti-corrosion layer was formed was attached to the laminate of the cycloolefin polymer film and the polarizer (A) prepared above with the same water-based adhesive (thickness: 100 nm). As a result, a cover dust laminate having a structure in which an upper protective layer (triacetyl cellulose film) / internalization layer / adhesive layer / polarizer (A) / adhesive layer / lower protective layer (cycloolefin polymer film) were sequentially laminated was prepared.

Example 2.

It proceeded in the same manner as in Example 1 except that the polarizer (B) of Preparation Example 2 was used.

Comparative Example 1.

It proceeded in the same manner as in Example 1 except that the polarizer (C) of Preparation Example 3 was used.

Comparative Example 2.

It proceeded in the same manner as in Example 1 except that the polarizer (D) of Preparation Example 4 was used.

Comparative Example 3.

It proceeded in the same manner as in Example 1, except that the polarizer (E) of Preparation Example 5 was used.

The properties of the cover dust laminate formed in each of the above examples are summarized and described in Table 1 below.

In Table 1 below, ΔT _s is an absolute value of the difference between the initial single transmittance T _i of the cover dust laminate and the single body transmittance T _a after the laminate is kept in an oven at 110° C. for 1000 hours.

Example 3.

The cover dust stack 100 formed in Example 1, an image generating device (LGE, LA080WV5) 20, a beam splitter (Edmund, B-plate Beamsplitter) 30, and a reflector (Edmund, S-mirror) ) (40) is arranged as shown in FIG. 4, and the direction of vibration of linearly polarized light incident on the cover dust stack is rotated with the absorption axis of the absorption type polarizer 110 of the cover dust stack. It was arranged so that the smallest of the angles formed was 70 degrees.

Then, after measuring the luminance of the screen formed by the reflected light 202 and the screen formed by the transmitted light 201 according to the above-described luminance measurement method, the luminance of the screen formed by the reflected light 202 is measured by the transmitted light 201. The luminance ratio divided by the luminance of the screen formed by is summarized and described in the following [Table 2].

Examples 4 to 8.

Except for the type of cover dust laminate, the direction of vibration of linearly polarized light incident on the cover dust laminate, and the angle formed by the absorption axis of the polarizer of the cover dust laminate, the smaller angle was applied as shown in [Table 2] below. It proceeded in the same manner as in Example 3.

10: head up display
100: cover dust laminate
110: absorption type polarizer
121: upper protective layer 122: lower protective layer
130: protective substrate
20 image generating device 200: output light 201: transmitted light 202: reflected light
30: beam splitter
40: reflector
50: windshield

Claims (15)

A cover dust laminate comprising a polyvinyl alcohol absorption polarizer having a potassium content of 0.35 to 0.7 wt% and a zinc content of 500 to 1,000 mg/kg. The cover dust laminate according to claim 1, wherein the absolute value of the change amount (ΔT _s ) of the single transmittance according to Equation 1 below is within 10%.
[Equation 1]
△T _s = T _a -T _i
In Equation 1, ΔT _s is the amount of change in the single transmittance, T _a is the single transmittance after the heat resistance test, and T _i is the initial single transmittance before the heat resistance test. The cover dust laminate according to claim 1, which satisfies the following Equations 2 and 3:
[Equation 2]
-b/a = 2.3 to 3.5:
[Equation 3]
0 <1000 ×(y-x) ≤ 3:
In Equations 2 and 3, b is the b value of the CIE color space of the cover dust stack, a is the a value of the CIE color space of the cover dust stack, and x is X of the CIE color space of the cover dust stack. Value, and y is the Y value of the CIE color space of the cover dust laminate. The cover dust laminate according to claim 1, which does not contain a reflective polarizer. The cover dust laminate according to claim 1, wherein a protective substrate is attached to an upper direction of the absorption type polarizer. The cover dust laminate according to claim 5, further comprising a lower protective layer in a lower direction of the absorption type polarizer. The cover dust laminate according to claim 6, further comprising an upper protective layer between the protective substrate and the absorption polarizer. The cover dust laminate according to claim 7, wherein the upper protective layer has an in-plane retardation. The cover dust laminate according to claim 7, wherein the in-plane retardation of the upper protective layer with respect to light having a wavelength of 550 nm is in a range of 100 to 400 nm. The cover dust laminate according to claim 1, wherein an adhesive layer, an adhesive layer, or a release film is not present in the outermost layer in the lower direction of the absorption type polarizer. An image generating device; And the cover dust stack according to claim 1, wherein the image generating device comprises: the image generating device so that an image emitted from the image generating device passes through the cover dust stack; And a head-up display on which a cover dust stack is disposed. The head-up display according to claim 11, wherein the image generating apparatus emits an image in a linearly polarized state. The image generating device and cover dust stacking according to claim 12, wherein a smaller angle of an angle formed by a vibration direction of linearly polarized light emitted from the image generating device and an absorption axis of a polarizer of the cover dust stack is in the range of 50° to 80°. Head-up display with sieves arranged. The head-up display device according to claim 11, further comprising a beam splitter, wherein the beam splitter is arranged such that an image output from the image generating device is transmitted through the cover dust stack through the beam splitter. The head-up display according to claim 11, further comprising a reflector, wherein the reflector is disposed so that the image emitted from the image generating device is reflected by the reflector and transmitted through the cover dust stack.

Images