Well in that case let's request a detailed evaluation by a independent
third party testing agency of each one of our windshields that provides evidence that they precisely meet the regulations for secondary image separation listed below.
Federal Register :: Federal Motor Vehicle Safety Standards; Glazing Materials
10. Visual Distortion Paragraph S5.15 of ANSI Z26.1 requires glazing materials used as windshields to undergo visual distortion and optical distortion tests. The purpose of these tests is to ensure safe driver visibility. To conduct the visual distortion test, the sample is placed in front of a light source and a circle is projected through the test specimen onto a screen. The tester then records the separation between the primary and secondary image.
The separation of the secondary and primary image is not allowed to exceed 3.95 minutes of arc or 8.9 mm (0.35 in). The procedure for the optical distortion test specifies that the sample be placed 7.62 m (25 ft) from a light source and moved toward the light source and away from the screen positioned behind the specimen at 127 mm (5 in) intervals. Each time the sample is moved, the tester observes the showdown pattern on the screen. The performance requirements of the test require that no light and dark patches representing a secondary image appear on the screen before the sample has been moved 635 mm (25 in) toward the light source. The test procedure requires that the sample be keep parallel to the screen at a right angle to the light source. Proposed Change The GTR visual distortion test, reflected in paragraph S6.11 of today’s proposed regulatory text, is conducted at the angle of installation rather than at a perpendicular angle. The latter is currently used in paragraph 5.15 of ANSI Z26.1. Since distortion is a function of the angle of incidence, the agency tentatively believes that testing at the angle at which the glazing will be installed is a more accurate representation of real world driving conditions. We note that the curvature of modern windshields at the margins makes it impractical to test the entire windshield for optical distortion at the angle of installation.
The GTR specifies three vision measurement areas, reflected in S6.15 of today’s proposed regulatory text, on which the optical distortion test is performed, which are designed to capture the area of the windshield used by the driver to see the forward roadway. The vision measurement areas used in the GTR are based on SAE J941, Motor Vehicles Drivers Eye Locations, JAN 2008. SAE J941 defines a range of eye positions developed from a statistical analysis of 2,300 drivers’ physiological data (with a male-to-female ratio of one to-one) performing a straight ahead driving task.29 Elliptical contours defining a range of eye positions were developed from a statistical analysis of this physiological data. These contours, or eye ellipses, offer a representation of a driver’s eye location and can be used to determine what a driver could see in the straight ahead driving task. The optical distortion test in the proposed GTR applies different vision testing areas to differing classes of vehicles. These vision testing areas are referred to in the GTR as Zones A, B and I. The defined vision testing areas Zones A and B apply to vehicles with a gross vehicle weight rating (GVWR) of 4,536 kg (10,000 lb) and less also referred to as light vehicles. Zone I applies to vehicles with a GVWR over 4,536 kg (10,000 lb). Zone A is defined as the area on the outer surface of the windscreen bounded by four planes. The first plane is parallel to the Y axis passing through V1 and inclined upwards at 3° from the X axis (plane 1 in Figure 18). The second is a plane parallel to the Y axis passing through V2 and inclined downwards at 1° from the X axis (plane 2 in Figure 18). The third plane is a vertical plane passing through V1 and V2 and inclined at 13° to the left of the axis (plane 3 in Figure 18). The fourth plane is a vertical plane passing through V1 and V2 and inclined at 20° to the right of the X axis (plane 4 in Figure 18). The four planes correspond to an area forming a box directly in front on the driver’s forward eye position.30 In order to determine the extended Zone A, the part of the windshield subject to the optical distortion test, the box formed by the four planes is extended to the vehicle’s center line and then to the area of windshield symmetric to Zone A on the opposite side of the vehicle’s centerline. The extended Zone A represents an area of the windshield extending horizontally across the center of the windshield. The area of the windshield that comprises extended Zone A must exhibit a maximum of 2 degrees of arc when subjected to the optical distortion test. Reduced Zone B consists of area along the bottom third of the windshield bounded by extended Zone A on the top, plane 9 (in figure 19(a)) on the bottom and plane 3 (in figure 19(a)) and a plane symmetrical to plane 3 on the opposite side of the vehicle centerline on the sides as well as the areas in the upper corners of the windshield separated from each other by the opaque area where the rear view mirror is mounted. The area of the windshield that comprises reduced Zone B must exhibit a maximum of 6 degrees of arc when subjected to the optical distortion test. Zone I, the defined vision testing applicable to vehicles with a GVWR over 4,536 kg (10,000 lb), is determined from the ‘‘O’’ point which represents the driver’s eye location. The ‘‘O’’ point is a point 625 mm above the R point which is determined using the three dimensional vehicle reference system described in ISO Standard 6549, Road Vehicles—Procedure for H- and R-point determination, December 16, 1999. Zone I is comprised of the area of the windshield bounded on the sides by vertical planes extending 15 degrees from the right and left of the O point and on the top by a horizontal plane extending from the O point to 10 degrees above horizontal and on the bottom by a horizontal plan extending from the O point to 8 degrees below horizontal. The area of the windshield comprising Zone I must exhibit no more than 2 degrees of arc when subjected to the optical distortion test. We tentatively believe that testing only in these areas sufficiently assesses the windshield’s optical properties, given that the eye ellipses appear to offer a good estimate of the windshield area typically used by the driver and taking into account practicality considerations. The performance requirements for Zones A and I are more stringent than Zone B because Zones A and I represent the area of the windshield used most by the driver to observe the forward roadway. Zone B is also the area of the windshield closer to the edge where the windshield displays greater curvature. Given that the agency is testing the windshield at the angle of installation rather than at a perpendicular angle, we have tentatively concluded that allowing a maximum of 6 degrees of arc in the reduced Zone B at the margins of the windshield is a reasonable approach to ensuring safe visibility through the windshield. We believe that other than specifying an area of the windshield to be tested, the procedure and performance requirements for these tests are equivalent with those currently included in FMVSS No. 205.
The secondary image test in paragraph S6.12 of today’s proposed regulatory text specifies two test procedures, only one of which the glazing must meet to satisfy the test’s requirements. The first test measures secondary image separation by projecting the image of a target through the windshield being tested and recording the secondary image shift of the target. Other than only applying this test to the defined vision testing areas described above, we believe that this procedure is substantially the same as the procedure specified for testing secondary image separation in paragraph 5.15.2.1 of ANSI Z26.1. The other is a collimation-telescope test. When a test piece exhibiting a secondary image is placed between the collimator and the telescope, a secondary image will appear on the polar co-ordinate system. The secondary image separation of the test piece can be determined by measuring the distance of the secondary image from the center of the polar co-ordinate system. This procedure differs from the procedure in ANSI Z26.1 where an image is projected through the test piece and secondary image separation is determined by visual inspection. The agency solicits comment on these proposed changes. We note that in its previous comment, Solutia expressed concern that the GTR’s method of testing the windshield using the installation angle ‘‘does not provide for testing the optics for a driver looking down or to the sides. A fixed angular test methodology can appropriately represent skewed driver vision (down or to the sides) for all vehicles, and reduces the test burden and ultimately costs for manufacturers.’’
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