FR2741698A1 - LIGHTING DEVICE WITH HALOGEN METALLIC VAPOR LAMPS - Google Patents

Abstract

The invention relates to a lighting device for a device for detecting defects in or on the surface of materials (1), in particular strip or sheet materials, comprising halogen lamps as well as cameras (2). . In order to increase the light intensity, metal vapor lamps (3) are used, which are placed at the focus of elliptical or parabolic mirrors (5).

Description

l

  Lighting device with metal vapor halogen lamps.

  The invention relates to a lighting device for a device.

  detection of faults inside or on the surface of materials, including

  both halogen lamps and cameras that detect faults.

  For the detection of defects on the surface or inside of material

  rials, such as glass strips, transparent films, strips of

  paper, etc ..., using cameras, the lighting requirements

  rages are high. Taking into account exposure times generally

  short, the light intensity must be very high. Long service life

  aunt, high stability and absence of parasitic phenomena (noise) are

  as many additional requirements that are placed on the lighting systems

  rage. Conclusive experiments have been made in the past with halogen incandescent lamps. These lamps have a lifespan of around 2000 hours, but their light output is relatively

  low and very high heat development.

  The invention aims to improve a lighting device

  of the type indicated in the introduction so as to obtain a lighting device

  rage which has a high lighting yield, a very long duration of

  life and good impact resistance.

  This object is achieved in accordance with the invention by the fact that halogen lamps are used, metal vapor halogen lamps.

  Halogen metal vapor lamps are sources of

  those of high quality light which are characterized by high lighting efficiency. The metal compounds present in the gas discharge increase the lighting efficiency by a factor of 4 compared to incandescent lamps. The shock resistance of these lamps corresponds

  substantially like that of a shockproof incandescent lamp.

  To focus the light beam, the lamps are

  carefully placed at the focal point of an elliptical mirror or a parabolic mirror. When the light intensity of a lamp is not sufficient, there are advantageously at least two lamps one next to the other, so that their light beams overlap in the plane to

control.

  By having a diffuser plate with very transparent

  high or an optic in front of the lamps, we can further improve the

  depending on the type of application.

  Other characteristics and advantages of the invention appear

  tront during the following description of examples of implementation

  made with reference to the drawings. These represent: FIG. 1, the basic arrangement of a lighting device for detecting faults inside or on the surface of materials, FIGS. 2 to 10, different variants of the lighting device in

  depending on the type of control to be performed.

  Figure 1 shows the basic arrangement of a lighting device.

  rage. Since when using exploration cameras per line, only one line is explored, or in the case of image cameras

  two-dimensional (also known as TDI cameras) which

  that only lines are explored, the light can be concentrated on a relatively narrow band. An elliptical or parabolic mirror is used to focus the light. The high and regular illumination of the control strip is obtained by placing one next to the other in a line, a variable number of light sources or lamps 3, the light beams of which overlap in the control plane. The residual vibration of the lighting depends on the scattering effect of the material to be checked and on the distance between the different light sources 3. It can be reduced by using a plate 6 diffusing the light in one direction or by cylindrical lenses arranged next to

other.

  Figures 2 to 9 show different variations of lighting in

  depending on the type of control to be performed.

  Figure 2 shows an arrangement for diffusion control.

  The material 1 to be checked acts as a diffuser. The reference 2 designates in all the figures a camera. The lamp 3 is arranged inside a

  elliptical mirror 5. The light beam is marked 4.

  As shown in FIG. 3, it may be necessary to place a diffuser plate 6 between the light source 3 and the control strip,

  when the surface is shiny and the reflected brush is very narrow.

  Figure 4 shows an arrangement for the detection of defects deflecting light by specular reflection. Between lamp 3 and the material

  1 to be examined is placed a diffuser plate 6 with a black area 8.

  FIG. 5 shows a control by transmitted light, for example

  full of paper 1. This type of control makes it possible to distinguish defects due to impurities and thickness defects from the direction of the signal; the "hole" type defect, on the other hand, poses problems since the camera 2, depending on the position of a hole, looks directly at a lamp 3

  (positive signal), next to a lamp 3 (negative signal).

  Figures 6 and 7 show variants which produce positive signals in the presence of "hole" type faults. In FIG. 6, a diffuser plate 6 with low attenuation is placed directly under the

  band 1; in FIG. 7, a diffusing strip 6 with low attenuation is placed

  created on the glass of the lighting unit or between the glass of said unit

lighting and material.

  FIG. 8 shows an arrangement for checking on a light background,

  for light absorbing defects in transparent materials 1.

  When it is necessary to search, in addition to absorbent faults, faults

  that cause diffraction, the bright background should be limited.

  Figure 9 shows an arrangement for monitoring on a dark background.

  bre. It detects faults that cause light diffraction. In particular during the control by transmitted light of bands 1 circulating at high speed, it may happen that the light intensity is not sufficient. It is possible in this case (see FIG. 10) to focus the light 4 into a narrower strip, using cylindrical lenses or

  optics 7, and thus increase the light intensity.

  In a preferred embodiment of the invention, the differences

  your light sources 3 are mounted in a housing 9 (see figure 1). The length of the housing 9 depends each time on the width to be checked. Advantageously, the lighting devices can be produced from individual projectors. These are fixed with the possibility of sliding on a rail whose length depends on the width to

  control. A lighting system of this type has great

  crashes and makes other installation work unnecessary.

  The advantages of a system of this type are as follows: 1. Adaptation to the length to be checked by cutting the fixing rail to the corresponding length, 2. Modification of the light intensity by modification of the number of lamps or by change of lamp type

(150 W / 400 W),

  3. optimum accessibility of lighting and lamps for maintenance and repairs and

  4. repetitive assembly work for the lighting unit

award-winning.

Claims (4)

  1. Lighting device for a device for detecting faults inside or on the surface of materials (1), comprising halogen lamps as well as cameras (2) which detect faults,   characterized in that the halogen lamps are halogen lamps (3)   metallic vapor genes. 2. Lighting device according to claim 1, characterized in that the lamps (3), for the purpose of focusing the light beam (4)   product, are arranged at the focus of an elliptical mirror or a parallel mirror bolique (5).   3. Lighting device according to claim 1 or the claim   cation 2, characterized in that at least two lamps (3) are arranged one beside the other and that their light beams (4) overlap in the plane to control.   4. Lighting device according to any one of the claims.   1 to 3, characterized in that a diffuser plate (6) or an opti-   that (7) is arranged in front of the lamps (3).