FR2790581A1 - Two-way communication sign is readable even when sun is low in sky - Google Patents

Abstract

In front of the support plate (10) is a contrast shutter (14) provided with a number of holes arranged in a corresponding matrix and aligned with the light diodes (12). The holes in the contrast shutter are not round in shape and their internal width in the horizontal is greater than in the vertical.

Description

The present invention relates to a road sign

  changing. Variable traffic signs are known which have a support plate carrying a large number of light diodes arranged in a matrix and which can be electrically individually controlled and a contrast screen placed in front of the support plate and provided with a large number of holes arranged in a corresponding matrix and aligned with the

light-emitting diodes.

  The light-emitting diodes are controlled so as to reproduce, depending on the intended use, text or other symbolic indications. Such changing traffic signs are used in various ways in particular

under road construction.

  The contrast screen placed in front of the light diodes serves on the one hand for the mechanical protection of these, and in particular increases the contrast by protecting to a large extent the light diodes against the incidence of stray light which would be reflected in these. This is particularly important when the changing traffic sign is lit by a low sun, i.e. in a situation where the readability of the

  changing traffic sign is altered.

  The problem underlying the invention was to create a road sign changing the type indicated at the start, the readability of which

  be assured when lit by a relatively low sun.

  To solve this problem, according to the invention, the holes in the contrast screen are not round and their width is greater in the direction

  horizontal than in the vertical direction.

  In a preferred embodiment, the holes are in the form of a segment of a circle and larger than a semicircle, the cord limiting the segment of

  circle of holes missing from the circle being horizontal.

  The holes may however also be for example rectangular, in the form

crescent or oval.

  The invention is explained below using a drawing, in which FIG. 1 is a front view of part of the contrast screen 14, and

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  fig. 2 is a side view of the part shown in FIG. 1.

  The changing traffic sign consists of a support plate 10 which carries a large number of light-emitting diodes 12 arranged in a matrix and which can be controlled electrically individually. In front of the support plate 10 is placed a contrast screen 14 which is provided with a large number of holes 16 arranged in a corresponding matrix and aligned with the light diodes. The holes 16 are in the form of a segment of a circle and larger than a semicircle, and the cord 18 which limits the missing segment of the circle to the circle is horizontal. The contrast screen 14 is placed relative to the support plate so that the axis

  light-emitting diodes 12 coincide with the center of the holes 16.

  Fig. 2 shows that the solar light which falls obliquely from the front (that is to say from the top right in the drawing) on the contrast screen 14 cannot reach the light diodes 12, because it is stopped by

  missing segment of circle in circle of holes 16.

  It goes without saying that other geometric shapes of the holes are imaginable; it is however important that the holes 16 are wider than tall so that the useful light emitted by the light diodes 12 is not

unnecessarily reduced.

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Claims (3)

  1. Changing road sign comprising - a support plate (10) which carries a large number of light-emitting diodes (12) arranged in a matrix and which can be controlled electrically individually, and - a contrast screen (14) placed in front of the plate support (10) and provided with a large number of holes (16) arranged in a corresponding matrix and aligned with the light-emitting diodes (12), characterized in that the holes (16) of the contrast screen (14) are not round and their width   is larger in the horizontal direction than in the vertical direction.   2. Changing traffic sign according to claim 1, characterized in that the holes (16) are in the form of a circle segment and larger than a semicircle, the cord (18) which limits the circle segment   missing from the circle being horizontal.   3. Changing traffic sign according to claim 1, characterized   by the fact that the holes (16) are rectangular.