BACKGROUND

[0001] This disclosure relates to methods and devices for measuring optical aberration, specifically to methods and devices for measuring optical aberration in transparent plastic articles that include a conductive pattern.

[0002] Transparent plastic articles such as polycarbonate glazing articles, are used in a wide variety of fields, such as automotive applications, due to their excellent mechanical properties such as impact resistance as well as heat resistance and transparency. For example, polycarbonate glazing articles can include sun/moon roofs and windows. The windows can include conductive pattern, such a defroster or an antenna. Defroster applications of the polycarbonate glazing articles can have problems. The conductive pattern can non-uniformly (e.g., heterogeneously) heats the polycarbonate glazing article which can lead to a non-uniform thermal expansion and cause optical aberration.

[0003] Clearly, optical aberration in a window application is undesirable.

Unfortunately, this optical aberration is not quantifiable.

[0004] Thus, there is a need for a technique to measure optical aberration. Such measurement could allow the evaluation of articles for suitability for specific uses. It would also provide insight into what modifications reduce optical aberration, thereby inspiring innovation.

SUMMARY

[0005] Disclosed, in various embodiments, are a device and methods for measuring optical aberration.

[0006] A method of measuring optical aberration caused by non-uniform or heterogeneous heating of a plastic article, preferably a polycarbonate glazing article, having a plurality of edges enclosing an area with two opposite sides, at least one of the opposite sides comprising a conductive pattern for defrosting the article, and the method comprising: projecting an image from a projecting source through the article onto a projecting surface before activating the conductive pattern, such that a base image is created on the projecting surface, wherein the projecting surface and the projecting source are each at a distance different from zero from the article; locally heating the article through activation of the conductive pattern; subsequently projecting the image through the article onto the projecting surface such that an active image is created on the projecting surface; and comparing the base image and the active image to determine the optical distortion.

[0007] A device for measuring optical distortion caused by inhomogeneous heating of a plastic article having a plurality of edges enclosing an area with two opposite sides, at least one of the opposite sides comprising a conductive pattern for defrosting the article, and the device comprising: a projecting source to project an image through the article; and a projecting surface for projecting the image thereupon; wherein the article is mounted between the projecting source and the projecting surface at a distance different from zero from each.

[0008] These and other features and characteristics are more particularly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following is a brief description of the drawings wherein like elements are numbered alike and which are presented for the purposes of illustrating the exemplary embodiments disclosed herein and not for the purposes of limiting the same.

[0010] FIG. 1 is an apparatus for measuring optical aberration;

[0011] FIG. 2 is a top view of the apparatus of FIG. 1 ;

[0012] FIG. 3 is the apparatus of FIG. 1 with an image projected through a polycarbonate glazing article at an angle;

[0013] FIG. 4A is a base image;

[0014] FIG. 4B is an active image and a base image;

[0015] FIG. 4C is a close up view of a portion of the active image and the base image;

[0016] FIG. 4D is a magnified view of section 4d from FIG. 4C;

[0017] FIG. 5 is the apparatus of FIG. 1 with an image projected through the polycarbonate glazing article at an angle perpendicular to a conductive pattern;

[0018] Fig. 6A is a base image;

[0019] Fig. 6B is an active image;

[0020] Fig. 6C is a comparison of the base image to the active image;

DETAILED DESCRIPTION

[0021] Disclosed herein is a method and device for measuring optical aberration in a plastic article (e.g., a transparent plastic article such as a polycarbonate glazing article).

Measuring optical aberration in a plastic article under different conditions and with different elements of the articles can enable reduced optical aberration and innovation The polycarbonate glazing article can be, for example, a window made from polycarbonate. The polycarbonate glazing article can have a variety of uses, for example the polycarbonate glazing article can be used in a rear window or tail light of a vehicle.

[0022] An example of a plastic article affected by optical aberration is a

polycarbonate glazing article. The article can have a plurality of edges enclosing an area with two opposite sides with a conductive pattern located on one of the sides. For example, the conductive pattern can include a plurality of conductive lines (e.g., a plurality of parallel lines that are parallel to at least one of the edges of the article). The conductive pattern can be activated to heat the article. Activation and deactivation can be achieved using a switch (e.g., an on/off switch) which connects or disconnects the conductive pattern to a power supply via a power source. When turned on, and electrically connected to the power supply, heat is generated. As the conductive lines generate heat, they heat the article. Since the heat moves out from the lines, the temperature of the article near the lines is greater than the temperature of the articles at a point half way between adjacent lines. In other words, the heating is heterogeneous. It is non-uniform. Such heating can cause optical aberration.

[0023] A method for measuring optical aberration comprises obtaining a base image and an active image and comparing the images. The base images can be obtained by projecting an image through the article onto a projecting surface before the conductive pattern is activated; i.e., while it is deactivated. The image can be projected from a projecting source, for example a laser, through the article onto a projecting surface. Optionally, the article, projecting source, and projecting surface can be mounted on a support or supports. The support(s) maintain the distance between the projecting source, the article, and the projecting surface for the generation of both the base image and the active image.

[0024] The article can be mounted to the support in a variety of ways, for example using a frame, a moveable frame, clamp, and so forth. The article, the projecting source, and the projecting surface can be moveable relative to each other, or fixed in place on the support. The article, the projecting source, and the projecting surface can also be moveable relative to the support, i.e. vertically. The projecting source and projecting surface are located on opposite sides of the article. The projecting source and the article can be arranged on the support such that an image can be projected from the projecting source through the desired portion of the article and onto the projecting surface. For example, the article can be mounted in between the projecting source and the projecting surface at a distance greater than zero. For example, the projecting source can be located a distance greater than 10 centimeters (cm), e.g., between 100 cm and 300 cm, or preferably about 200 cm, from the article. The projecting surface can be, for example, a sheet of paper, a camera lens, or other means for recording the projected image.

[0025] The image can be projected from the projecting source at a predetermined angle with respect to the conductive pattern in the article, for example, the image can be projected perpendicular to the conductive pattern. The image can form an angle from 0 to 90 degrees, for example an angle from 5 to 85 degrees, for example from 25 to 55 degrees, with a line of the conductive pattern. (See FIG. 3, angle Θ) The projected image can cross the conductive pattern, at least partially, or the image can cross the entire conductive pattern. The image can be any shape, preferably the image is a line. The resulting image can be the base image, i.e. when the conductive pattern is not activated. The base image can be recorded onto the projecting surface.

[0026] After the base image as been recorded, the conductive pattern can be activated, for example, by turning the on/off switch to on, thereby providing power to the conductive lines. Once the article is heated, an active image can be obtained. Optionally, the temperature of the article can be monitored such that one the article attains a desired temperature, the active image can be formed. For example, the article can be heated by the conductive pattern to a temperature of less than or equal to 70°C. The temperature of the article can be detected with a temperature detector (such as an infrared camera). The temperature detector can be mounted on a support, or can be separate from a support.

[0027] Once the article is heated, the projecting source can project the image through the article onto the projecting surface, creating an active image. The active image can be recorded onto the projecting surface. Optionally, the active image can be overlaid on the base image. The active image can include interruptions from thermal expansion caused by the activation of the conductive pattern. In other words, the active image can be in segments. (See FIG. 6)

[0028] Once the active image has been recorded, the active image can be compared to the base image to determine optical aberration, for example optical distortion. If the base image and the active images were formed from a projected image that was oriented at a non- parallel and non-perpendicular angle with respect to the conductive lines (e.g., at an angle of other than 90 degrees and 0 degrees), then an angle of distortion can be determined. In such a case, the base image is formed, and the active image is formed over the base image. The active image, although formed from a projected image that was projected at the same angle for producing the base image and the active image, if there is optical aberration the active image will have a different angle than the base image. The angle of distortion is the angle between the base image and the segments of the active image. (See for example, FIG. 4D) The angle of distortion between one, multiple, or all of the active image segments and the base image segments can be measured. If the angle of distortion is measured between more than one active image segment and base image segment, the angles of distortion can be compared and statistically analyzed to determine the effect of the conductive pattern for defrosting on optical aberration, for example optical distortion.

[0029] If the projected image is a line, and the projected image and the conductive pattern are perpendicular to each other, the active image and the base image can include interruptions, i.e. comprise multiple line segments. The average length of the interruptions of the base image can be compared with the average length of the interruptions of the active image to measure optical distortion. The interruptions of the active image can be longer than the interruptions of the base image, because the conductive pattern can create more distortion from thermal expansion when conductive pattern is activated. The length of the interruptions of the active image and the interruptions of the base image can be compared and statistically analyzed to determine the effect of the conductive pattern on optical aberration.

[0030] A more complete understanding of the components, processes, and apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures (also referred to herein as "FIG.") are merely schematic representations based on convenience and the ease of demonstrating the present disclosure, and are, therefore, not intended to indicate relative size and dimensions of the devices or components thereof and/or to define or limit the scope of the exemplary embodiments. Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.

[0031] FIG. 1 shows a device for measuring optical aberration. As shown in FIG. 1, a projecting source (1) can be mounted to an end of a support (30). An article (10) can be mounted to the opposite end of the support (30). The projecting source (1) can be mounted a distance (12) from the article (10). A projecting surface (40) can be provided opposite the projecting source (1). A temperature detector (35) can be arranged, as shown in FIG. 2, on the same side of the support (30) as the projecting source (1) such that the temperature detector can determine the temperature of the article (10).

[0032] As show in FIG. 3, the projecting source (1) can project an image (15) through the article (10). The article (10) can include a conductive pattern for defrosting (20). The image (15) can be projected from the projecting source (1) at a predetermined angle relative to one edge of the article (10). The image (15) can be projected through the article (10), such that the image (15) can be recorded onto the projecting surface (40).

[0033] When the image (15) is projected through the article (10) at an angle different from 0 or 90 degrees with the lines of the conductive pattern (20), and the conductive pattern (20) deactivated, the base image can be recorded onto the projecting surface (40). FIG. 4A depicts a base image (110). When the image (15) is projected through the article (10) with the conductive pattern (20) activated, the active image can be recorded onto the projecting surface (40). FIG. 4B depicts an active image (105). The angle of distortion (100) between the active image (105) and the base image (110) can be measured, as shown in FIGS. 4C and 4D.

[0034] As shown in FIG. 5, the projecting source (1) can project the image (15) at an angle perpendicular to the conductive pattern (210). When the image (15) is projected through the article (10) at this perpendicular angle, and the conductive pattern (210) is deactivated, the base image (310) can appear broken into multiple segments, as shown in FIG. 6A. When the image (15) is projected through the article (10) at this perpendicular angle and the conductive pattern (210) is activated, the active image (300) can be broken into multiple segments, as shown in FIG. 6B. This active image (300) can include line segments and interruptions of different lengths than those of the base image (310), as shown in FIG. 6C.

[0035] Set forth below are some aspects of the device and method disclosed herein.

[0036] Aspect 1: A method of measuring optical aberration caused by non-uniform or heterogeneous heating of an article, preferably a plastic article such as a polycarbonate glazing article, having a plurality of edges enclosing an area with two opposite sides, at least one of the opposite sides comprising a conductive pattern for defrosting the article, and the method comprising: projecting an image from a projecting source through the article onto a projecting surface before activating the conductive pattern, such that a base image is created on the projecting surface, wherein the projecting surface and the projecting source are each at a distance different from zero (e.g., a distance greater than zero) from the article; locally heating the article through activation of the conductive pattern; subsequently projecting the image through the article onto the projecting surface such that an active image is created on the projecting surface; and comparing the base image and the active image to determine the optical distortion.

[0037] Aspect 2: The method of Aspect 1, wherein the image is projected through the article in a perpendicular direction to the conductive pattern.

[0038] Aspect 3: The method of Aspect 1 or 2, wherein the conductive pattern comprises a plurality of parallel lines that are parallel to at least one of the enclosing edges.

[0039] Aspect 4: The method of any of the preceding Aspects, further comprising recording the base image on the projecting surface, and overlaying the active image on the base image before comparing the base image and the active image.

[0040] Aspect 5: The method of any of the preceding Aspects, wherein the image is a line that crosses the conductive pattern at least partly, thereby forming a projected line with at least one interruption on the projecting surface.

[0041] Aspect 6: The method of Aspect 5, wherein the line forms an angle between 0 to 90 degrees, preferably an angle between 5 and 85 degrees, more preferably between 25 and 55 degrees with a line of the conductive pattern.

[0042] Aspect 7: The method of Aspect 6, wherein the line forms an angle different from 0 degrees or from 90 degrees with a line of the conductive pattern, and the method further comprises determining the angle enclosed between a line of the base image and a line of the active image.

[0043] Aspect 8: The method of Aspect 6, wherein the line and a line the conductive pattern are perpendicular to each other, and the method further comprises comparing the average length of the interruptions of a line of the base image with the average length of the interruptions of a line of the active image.

[0044] Aspect 9: The method of any of the preceding aspects, wherein the conductive pattern is connected to a power source, and wherein activation of the conductive pattern is achieved by switching on the power source.

[0045] Aspect 10: The method of any of the preceding aspects, wherein the distance between the glazing device and the projecting source is between 100 and 300 cm, preferably around 200 cm. [0046] Aspect 11 : The method of any of the preceding aspects, further comprising monitoring the local heating of the conductive pattern by means of a temperature detector.

[0047] Aspect 12: The method of any of the preceding aspects, wherein the article is a polycarbonate rear window for a vehicle.

[0048] Aspect 13: The method of any of the preceding aspects, wherein the optical aberration is at least one of optical distortion, color shifting, defocusing and polarization effect.

[0049] Aspect 14: The method of any of the preceding aspects, wherein the article is a polycarbonate glazing article with a defroster.

[0050] Aspect 15: The method of any of the preceding aspects, wherein the distance between the glazing device and the projecting source is between is greater than 10 cm, preferably 25 cm to 400 cm, or 50 cm to 300 cm.

[0051] Aspect 16: A device for measuring optical distortion caused by

inhomogeneous heating of an article, preferably a plastic article, having a plurality of edges enclosing an area with two opposite sides, at least one of the opposite sides comprising a conductive pattern for defrosting the article, and the device comprising: a projecting source to project an image through the article; and a projecting surface for projecting the image thereupon; wherein the article is mounted between the projecting source and the projecting surface at a distance different from zero from each.

[0052] Aspect 17: The device of Aspect 16, further comprising a power source to activate the conductive pattern and non-uniformly heat the article.

[0053] Aspect 18: The device of Aspect 16 or 17, wherein the two opposite sides of the article each face either the projecting source or the projecting surface, such that a plane of the article is perpendicular to a projecting direction.

[0054] As used herein, "transparent" refers to sufficient transparency such that the projecting source can project an image through the article to form an image on the projecting surface.

[0055] In general, the invention may alternately comprise, consist of, or consist essentially of, any appropriate components herein disclosed. The invention may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants or species used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present invention. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of "less than or equal to 25 wt , or 5 wt% to 20 wt ," is inclusive of the endpoints and all intermediate values of the ranges of "5 wt% to 25 wt ," etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group. "Combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. Furthermore, the terms "first," "second," and the like, herein do not denote any order, quantity, or importance, but rather are used to denote one element from another. The terms "a" and "an" and "the" herein do not denote a limitation of quantity, and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. "Or" means "and/or." The suffix "(s)" as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the film(s) includes one or more films). Reference throughout the specification to "one embodiment", "another embodiment", "an embodiment", or "one aspect", "another aspect", "an aspect" and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.

[0056] "Optional" or "optionally" means that the subsequently described event or circumstance can or cannot occur, and that the description includes instances where the event occurs and instances where it does not. Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. A "combination" is inclusive of blends, mixtures, alloys, reaction products, and the like.

[0057] Unless otherwise specified herein, any reference to standards, regulations, testing methods and the like, such as ASTM D1003, ASTM D4935, ASTM 1746, FCC part 18, CISPRl l, and CISPR 19 refer to the standard, regulation, guidance or method that is in force at the time of filing of the present application.

[0058] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference. [0059] While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.