ECE R.4 Uniform provisions concerning the approval of devices forthe illumination of rear registration plates of power-drivenvehicles and their trailers

This Regulation applies to rear registration plate lamps for vehicles of categories M, N, O, and T’.
“Rear registration plate lamp” means the device for the illumination of rear registration plates, hereinafter called “illuminating device”, which illuminates the rear registration plate by reflection. For the approval of this device, the illumination of the space to be occupied by the plate is determined.

Colour of light
The light of the lamp used in the illuminating device must be sufficiently colourless not to cause any appreciable change in the colour of the registration plate.
Incidence of the light

The manufacturer of the illuminating device shall specify one or more or a field of positions in which the device is to be fitted in relation to the space for the registration plate; when the lamp is placed in the position(s) specified by the manufacturer the angle of incidence of the light on the surface of the plateshall not exceed 82 at any point of the surface to be illuminated, this angle being measured from the extremity of the device’s illuminating area which is furthest from the surface of the plate. If there is more than one illuminating device, the fore going requirement shall apply only to that part of the plate intended to be illuminated by the device concerned.

When the device has one outer edge of the illuminating surface that is parallel to the surface of the registration plate, the extremity of the illuminating surface of the device which is furthest from the surface of the plate is the middle point of the edge of the illuminating surface, which is parallel to the
plate and is furthest from the surface of the plate
.
The device must be so designed that no light is emitted directly towards the rear, with the exception of red light if the device is combined or grouped with a rear lamp
Measuring procedure

Luminance measurements shall be made on a diffuse colourless surface with known diffuse reflection factor3. The diffuse colourless surface shall have the dimensions of the registration plate or the dimension exceeding one measuring point. Its centre shall be placed in the centre of the positions of the measuring points
.
This diffuse colourless surface(s) shall be placed in the position normally occupied by the registration plate and 2 mm in front of its holder.

Luminance measurements shall be made perpendicularly to the surface of the diffuse colourless surface with the tolerance of 5 in each direction at the points shown in Annex 3 to this Regulation, each point representing a circular area of 25 mm in diameter. The measured luminance shall be corrected for
the diffuse reflection factor 1.0

LISUN following instruments fully meet ECE R.4 Uniform provisions concerning the approval of devices forthe illumination of rear registration plates of power-drivenvehicles and their trailers

LSG-1950 Goniophotometer for Automotive and Signal Lamps

LSG-1950S Goniophotometer for Traffic Signal Lamps