UN R46 Supplement 9 (04 series) · UNECE Regulation No. 46 (ECE R46) — Uniform provisions concerning the approval of devices for indirect vision and of motor vehicles with regard to the installation of these devices.
UN R46 — Supplement 9 to the 04 series of amendments
Supplement 8 → 9
- What changed
- The reflecting surface of a mirror must now be flat or convex, instead of flat or spherically convex (para. 6.1.2.2.1.).
- A “spherical surface” is now a convex surface whose horizontal and vertical measured radii of curvature comply with paragraphs 6.1.2.2.2 and 6.1.2.2.4.
- An “aspherical surface” is now a convex surface that may have variable radii of curvature in both the horizontal and the vertical direction.
- Why
- The aim is to allow free form mirrors as an alternative to spherical mirrors.
- The purpose is to improve the quality of the reflected images and optimize the mirror size for a given field of vision.
- In reality, because of the production process, each point of a mirror surface deviates at random from the ideal sphere.
Q1What changed4 changes
Definition of “spherical surface” (para. 2.1.1.7.)
Paragraph 2.1.1.7. now defines a “spherical surface” as a convex surface. In both the horizontal and the vertical direction, its measured radii of curvature comply with the provisions of paragraphs 6.1.2.2.2 and 6.1.2.2.4. Before this supplement, a spherical surface had a constant and equal radius in all directions.
Definition of “aspherical surface” (para. 2.1.1.8.)
Paragraph 2.1.1.8. now defines an “aspherical surface” as a convex surface. It may have variable radii of curvature in both the horizontal and the vertical direction. Before this supplement, an aspherical surface had a constant radius in one plane only.
Definition of “aspherical mirror” (para. 2.1.1.9.)
An “aspherical mirror” is a mirror composed of a spherical and an aspherical part. The definition now says that the spherical part is as defined in 2.1.1.7 and the aspherical part as defined in 2.1.1.8. Before, the text said that the curvature of the main axis of the mirror “is defined” in the x/y coordinate system. Now it says that, as an example, this curvature “may be defined” in that way. As before, the transition of the reflecting surface from the spherical to the aspherical part must be marked.
Reflecting surface of a mirror: flat or convex (para. 6.1.2.2.1.)
The reflecting surface of a mirror must now be either flat or convex. Before this supplement, the text said “either flat or spherically convex”. As before, exterior mirrors may have an additional aspherical part if the main mirror fulfils the requirements of the indirect field of vision.
Q2Why it changed
- Proposed by
- Expert from Italy
- Working party
- GRSG, 119th session (October 2020)
Reasons
The aim is to allow free form mirrors as an alternative to spherical mirrors. The intention is that spherical mirrors continue to be offered on the market.
Sources (3)
“to adapt the provisions of UN Regulation No. 46 to allow the usage of free form mirrors as an alternative to spherical mirrors”
“The intention is to let the current spherical product continue to be offered on the market”
“on amendments of definitions to cover 'free form' mirrors”
The purpose is better quality in optical vision through new surface designs and manufacturing processes. The intention is also to allow a new generation of optical reflecting mirrors on the market. These mirrors are to improve the quality of the reflected images and optimize the mirror size for a given field of vision.
Sources (2)
“The purpose of the proposal is to offer an update of quality in optical vision by adopting innovative surface designs and manufacturing processes.”
“allow for the new generation of optical reflecting mirrors being offered to the market in order to improve the quality of the reflected images and optimize the mirror size for a given field of vision”
Ideally, vehicles should have perfectly spherical mirrors. In reality, because of the production process, each point of a mirror surface deviates at random from the ideal sphere. Because of the production tolerances, real spherical mirrors on cars actually have random free form surfaces. A free form design that complies with the geometrical verification procedure in the field of view area can use the allowed tolerance (0.15 r). This will give the opportunity to optimize the optical performance of the mirror. Over that surface, the free form mirror will still comply with the Average Radius as defined in the Regulation.
Sources (6)
“Vehicles should ideally be equipped with perfectly spherical mirrors.”
“In reality, because of the production process, all of the mirrors have been provided with surfaces in which each point is randomly deviated with respect to the position on the ideal sphere.”
“Taking into account the production tolerances, real spherical mirrors installed on the cars, even those better produced, actually have random free form surfaces”
“Complying with the actual geometrical verification procedure in the field of view area, as defined in the Regulation, and utilizing the allowed tolerance (0.15 r)”
“will bring the opportunity to optimize the optical performances of the mirror through the appropriate optical software tools”
“The Average Radius as defined in the Regulation will still be complied with by the free form mirror over that reflecting surface.”
In the last ten years, many studies showed that non-spherical surfaces can improve the optical performance. The optical axis of a spherical mirror on a car is rotated and decentred from the axis of the driver's eyes. As a result, the images are squeezed in the horizontal direction. A free form surface can compensate for this position and give images with the right proportions. Current manufacturing processes can reliably produce free form surfaces.
Sources (4)
“In the last ten years many studies have been done on the optical behaviour of non-spherical surfaces, all of them showing that the usage of non-spherical surfaces allows to get improvements of the optical performances.”
“the optical axis of a spherical mirror installed on a car is rotated and decentred with respect to the axis of the driver’s eyes; this condition leads to images squeezed in the horizontal direction”
“The adoption of a free form surface can compensate the asymmetrical position of the mirrors, reflecting images with the right proportions.”
“Current manufacturing processes of mirrors can be used to reliably produce free form surfaces.”
Depending on their design, free form surfaces can reduce the optical distortion. This is valuable especially for the aspherical surface of an aspherical mirror. The reason is that the simple function in paragraph 2.1.1.9. gives a poor quality of the reflected image. Other possible benefits are a smaller blind spot and a smaller mirror for the same field of view.
Sources (4)
“benefits related to free form surfaces which, according to the way they have been designed, can be one or more of the following”
“Reduction of the optical distortion (this target is valuable especially for the aspherical surface of an aspherical mirror, because the simple function given in par. 2.1.1.9. actually results in a poor quality of the reflected image”
“Blind spot reduction”
“Mirror overall size reduction, while keeping the same field of view”
Document trail
- 2020-01ProposalECE/TRANS/WP.29/GRSG/2020/6Proposal by the expert from Italy
- —Working party adoptsECE/TRANS/WP.29/GRSG/98GRSG session report, para. 31
- 2020-12Sent to WP.29ECE/TRANS/WP.29/2021/19Text that GRSG sent to WP.29 and AC.1
- 2021-03WP.29 adoptsECE/TRANS/WP.29/1157Adopted at the 183rd session (session report, para. 137)
- 2021-09-30In forceC.N.314.2021.TREATIES-XI.B.16.46UN depositary notification
Q3Who is affected
Vehicle manufacturer
- Check the reflecting surfaces of your mirrors against paragraph 6.1.2.2.1. and the changed definitions in paragraphs 2.1.1.7. to 2.1.1.9.
- Update the documents that describe a reflecting surface as “spherically convex” (para. 6.1.2.2.1.).
Component supplier
- Check your mirror surface designs against the changed definitions of “spherical surface” and “aspherical surface” (paras. 2.1.1.7. and 2.1.1.8.).
- Make sure that the horizontal and vertical radii of curvature of a spherical surface comply with paragraphs 6.1.2.2.2 and 6.1.2.2.4.
- Check whether your aspherical mirror designs depend on the curvature of the main axis in paragraph 2.1.1.9. The text now gives it only as an example.
Technical service / Approval authority
- Check the measured radii of curvature of a spherical surface in both the horizontal and the vertical direction (para. 2.1.1.7.).
- Be ready for aspherical surfaces with variable radii of curvature in both the horizontal and the vertical direction (para. 2.1.1.8.).
- If your test checklists ask for a “spherically convex” reflecting surface, update them (para. 6.1.2.2.1.).
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ⓘ This report gives advice only. It is not legal or type-approval advice.
More UN R46 change reports
- 07 series — Supplement 2
- 07 series — Supplement 1
- 07 series — Base text
- 06 series — Supplement 2
- 06 series — Supplement 1
- 06 series — Base text
- 05 series — Supplement 2
- 05 series — Supplement 1
- 05 series — Base text
- 04 series — Supplement 10
- 04 series — Supplement 8
- 04 series — Supplement 7
- 04 series — Supplement 6