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WO2003062755A1 - Dispositif d'illumination - Google Patents

Dispositif d'illumination Download PDF

Info

Publication number
WO2003062755A1
WO2003062755A1 PCT/NL2003/000042 NL0300042W WO03062755A1 WO 2003062755 A1 WO2003062755 A1 WO 2003062755A1 NL 0300042 W NL0300042 W NL 0300042W WO 03062755 A1 WO03062755 A1 WO 03062755A1
Authority
WO
WIPO (PCT)
Prior art keywords
mirrors
lamps
lens
leds
parallel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/NL2003/000042
Other languages
English (en)
Inventor
Rowland De Rodde
Leopold Cornelis Petrus Keizer
Gerardus Wilhelmus Adrianus Maria Van Der Heijden
Gerrit Polder
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Plant Research International BV
Original Assignee
Plant Research International BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Plant Research International BV filed Critical Plant Research International BV
Publication of WO2003062755A1 publication Critical patent/WO2003062755A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/09—Beam shaping, e.g. changing the cross-sectional area, not otherwise provided for
    • G02B27/0938—Using specific optical elements
    • G02B27/0994—Fibers, light pipes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V2200/00—Use of light guides, e.g. fibre optic devices, in lighting devices or systems
    • F21V2200/40—Use of light guides, e.g. fibre optic devices, in lighting devices or systems of hollow light guides
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]

Definitions

  • the present invention relates to a device for illuminating a (three dimensional) object in a measuring device.
  • halogen lamps for illuminating the object in imaging spectrographs, often in combination with glass fibres and line arrays (glass fibre bundle in which all glass fibres are positioned adjacently) .
  • Halogen lamps have the drawback of the spectral emission in the range between 400 and 450 nm being very low. For various uses, for instance the measuring of flowers (ornamental plants), it is desirable to measure the reflection in this spectral range.
  • LEDs Light Emitting Diodes emitting these wavelengths are available.
  • the intensity of LEDs is very low, however.
  • One LED can only evenly illuminate a very small object.
  • the use of a row of LEDs does not result in an even illumination.
  • a device for illuminating a (three-dimensional) object in a measuring device comprising a row of several lamps, a mirror cavity comprising two plane-parallel mirrors, the one mirror being placed above the other and the reflecting surfaces of the mirrors facing each other, and a cylindrical lens, wherein the row of lamps is placed at the rear edge of the mirrors between the mirrors and the lens is placed parallel near the front edge of mirrors, such that the light of the lamps reflected by the plane-parallel mirrors is directed by the lens as a virtually parallel beam of light on the object to be illuminated.
  • an illumination having an equalised intensity is achieved.
  • the achieved illumination has an evenly running intensity distribution in the three dimensions x, y and z, the z- direction being the direction of the beam coming from the device and the x- and the y-direction being perpendicular to each other and in a plane perpendicular to the direction of the light beam.
  • the y-direction is perpendicular to a plane parallel to the parallel mirrors.
  • the device according to the invention enables to combine a number of relatively weak lamps such that an illumination having sufficient intensity is achieved.
  • the term lamp refers to a device serving to illuminate.
  • preferably light emitting diodes (LEDs) are used.
  • LEDs light emitting diodes
  • the cylindrical lens to be used in the device according to the invention is a positive lens, that means a lens which converges the incident rays.
  • cylindrical lens does not only refer to single-axis spherical lenses but also to single-axis a-spherical lenses.
  • the lens used in the device according to the invention can also be a part of a cylinder.
  • the cylindrical lens of the device according to the invention is a positive lens having at least one refracting surface that is a part of a cylindrical surface wherein a cylindrical surface refers to a surface described by straight lines that each are parallel to a straight line and pass through a certain curve. Said curve is not limited to circular curves.
  • the mirror cavity and the axis of the cylindrical lens will be a little larger than the focal distance of the lens.
  • the optimal position of the lens that means the position providing a beam which is as parallel as possible, can very easily be established by experiments.
  • FIG. 1 schematically shows a cross-section of an embodiment of a device according to the invention.
  • 1 refers to a LED of a row of LEDs clamped in between an upper mirror 2 and a lower mirror 3, which have been provided at the lower and upper side, respectively, with a reflecting surface and which together form a mirror cavity.
  • the intensity distribution of the light coming from the lamps has been equalised in the x- and y-direction.
  • the light leaving the mirror cavity is guided by a rod lens (cylindrical lens) 4, the focus of which is situated outside the mirror cavity, to form a parallel beam so that an even intensity distribution is also achieved in the z-direc- tion.
  • the mirrors form the upper and lower walls of the mirror cavity.
  • the front side of the mirror cavity is open.
  • the rear side of the cavity is closed off by the row of lamps.
  • the side walls of the mirror cavity preferably are closed.
  • the surface of the side walls preferably is not reflecting. Most preferably the side walls are frosted black.
  • the mirrors generally have a rectangular shape. The length of the mirror, the distance between lamps and front side, is considerably larger than the height of the mirror cavity, the dis- tance between the mirrors.
  • the width of the mirror depends on the wanted width that has to be illuminated. When a larger illumination surface is wanted, the number of
  • LEDs in the row can be increased.
  • the height of the mirror cavity is determined by the diameter of the LEDs.
  • the effect of the mirror cavity is halved. In general it is desirable then to make the mirror cavity twice as long. Increasing the height of the mirror cavity also has consequences for the lens diameter, object distance and degree of parallelism of the beam.
  • High-intensity LEDs having a very small diameter therefore are preferred.
  • an equalised intensity distribution over a broad wavelength range can be achieved.
  • a number of devices having LEDs with a contiguous emission spectrum can also be combined.
  • the nature of the object is in fact unlimited. Due to the equalised intensity distribution of the light beam obtained with the device according to the invention, it is not necessary that the object is flat.
  • the present invention can for instance be used for illuminating fruits, plants, flowers or seeds, for instance in an industrial sorting device.
  • a mirror cavity consisting of two plane-parallel mirrors placed at a distance of 5 mm from each other and having a width of 1 25 mm made of 1 mm thick material
  • 50 bright blue light emitting LEDs (by Agilent, type HLMP-DB25-P0000) having an intensity of 100 mcd and an opening angle of 25° and a length of 8.71 mm cm were placed, wherein the centres of the LEDs were situated at a distance of 50 mm from the front edge of the mirrors.
  • a rod lens in the shape of a plastic (perspex) cylinder having a diameter of 50 mm and a length of 1 30 mm was mounted, such that the axis of the cylinder ran parallel to the front edge of the mirror cavity and was situated in a plane parallel to the mirrors.
  • the mirrors and the lens were mounted in a plastic box.
  • Figure 2 shows the intensity distribution obtained with the above-mentioned example of a device according to the invention.
  • the reflection values on a white background were measured by means of a digital camera.
  • the reflection pattern obtained with the device according to the invention is shown at the bottom.
  • the reflection pattern of a single row of LEDs is shown at the top.
  • Figure 3 shows a graphical depiction of the intensity distribution obtained with the above example of a device according to the invention measured by means of a digital camera.
  • the x- and y-axis are spatial axes in a plane placed perpendicular in the beam and show pixels (image dots). The image has not been calibrated, but 1 pixel approximately corresponds to 1 mm 2 .
  • the z-axis represents the intensity in grey values.
  • the intensity distribution obtained with the device according to the example is indicated by a, whereas b refers to the intensity distribution of a single row of LEDs.
  • Figure 4 shows the intensity distribution of figure 3 in contour lines. The intensity has not been calibrated, but has been shown in grey values, 40 grey values per step.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)

Abstract

L'invention concerne un dispositif pour illuminer un objet comprenant une rangée de plusieurs lampes, une cavité de miroirs comprenant deux miroirs à plans parallèles placés l'un au-dessus de l'autre et une lentille cylindrique positive, la rangée de lampes est placée au niveau du bord arrière des miroirs entre les miroirs et la lentille est placée parallèle au bord avant de la cavité de miroirs, de telle manière que la lumière des lampes réfléchie par la cavité de miroirs est dirigée avec une répartition d'intensité égalisée sur l'objet à illuminer.
PCT/NL2003/000042 2002-01-23 2003-01-21 Dispositif d'illumination Ceased WO2003062755A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1019823 2002-01-23
NL1019823A NL1019823C2 (nl) 2002-01-23 2002-01-23 Verlichtingsinrichting.

Publications (1)

Publication Number Publication Date
WO2003062755A1 true WO2003062755A1 (fr) 2003-07-31

Family

ID=27607204

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL2003/000042 Ceased WO2003062755A1 (fr) 2002-01-23 2003-01-21 Dispositif d'illumination

Country Status (2)

Country Link
NL (1) NL1019823C2 (fr)
WO (1) WO2003062755A1 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0691552A2 (fr) * 1994-06-28 1996-01-10 Corning Incorporated Appareil pour illumination uniforme d'une vanne de lumière
WO1999058959A1 (fr) * 1998-05-11 1999-11-18 Pioneer Hi-Bred International, Inc. Spectrometrie de proche infrarouge pour analyses de substances en temps reel
US6036328A (en) * 1995-05-23 2000-03-14 Sharp Kabushiki Kaisha Plane-shaped lighting device and a display using such a device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0691552A2 (fr) * 1994-06-28 1996-01-10 Corning Incorporated Appareil pour illumination uniforme d'une vanne de lumière
US6036328A (en) * 1995-05-23 2000-03-14 Sharp Kabushiki Kaisha Plane-shaped lighting device and a display using such a device
WO1999058959A1 (fr) * 1998-05-11 1999-11-18 Pioneer Hi-Bred International, Inc. Spectrometrie de proche infrarouge pour analyses de substances en temps reel

Also Published As

Publication number Publication date
NL1019823C2 (nl) 2003-07-25

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