EP4195173A1

EP4195173A1 - Uv lighting device

Info

Publication number: EP4195173A1
Application number: EP21306730.9A
Authority: EP
Inventors: Jack MCKINLEY; Guillaume Mazeaud
Original assignee: TPL Vision UK Ltd
Current assignee: TPL Vision UK Ltd
Priority date: 2021-12-09
Filing date: 2021-12-09
Publication date: 2023-06-14

Abstract

Lighting device (10) for illuminating an object (O) to be controlled, comprising:
- at least one light source (20) for illuminating the object (O), said light source (20) being configured to emit at least one ultraviolet wavelength,
- a housing (30) containing the at least one light source (20) and comprising a housing opening (32) for receiving the object to be illuminated, and a control window (34) for enabling the visualization of the object (O) illuminated by the at least one light source (20),
said housing (30) comprising an inner wall (36) configured for reflecting the light emitted by said at least one light source (20) toward the object (O) to be illuminated.

Description

The invention concerns an ultraviolet (UV) lighting device.
The lighting devices are used in the Machine Vision and Identification market. New requirements from the emerging markets are required by law to put UV tax stamps (Excise Stamps) on their products. These stamps must be inspected for print quality and tracked to ensure quality in the luxury goods market. This new incentive is being pushed by governing agencies and is creating standards for the producers of luxury goods, such as tobacco, in the emerging markets. The standards require producers from these new markets to apply unique identifiers for Product Track and Trace systems to secure the supplier source and location. The tax stamp shows the necessary taxes have been paid and also provides proof that the product is genuine. It is typical that these tax stamps make up three quarters of the cost to produce tobacco products, so it is critical that the suppliers ensure the presence and quality of such a stamp. The tax stamp also provides a couple of secondary uses such as showing the product has not been tampered with. It is often referred to as a security seal.
Tax stamps have existed for many years, however, the use of UV inks and fibres on the tax stamp is a new measure against counterfeiting of these luxury goods.
There is therefore a need for benefiting from lighting devices enabling to facilitate the identification of stamps containing UV features such as UV inks and fibres.
An aim of the invention is to at least partially meet this need.

Summary of the Invention

The invention proposes a lighting device for illuminating an object to be controlled, comprising:

at least one light source for illuminating the object, said light source being configured to emit at least one ultraviolet wavelength,
a housing containing the at least one light source and comprising a housing opening for receiving the object to be illuminated, and a control window for enabling the visualization of the object illuminated by the at least one light source,

In the invention, the object is advantageously illuminated with a homogeneous and diffuse light.
The control window may be opposite the housing opening.
The lighting device of the invention is easy to use for the user, it integrates a full vision solution, with multiple possible wavelengths, which may help the user to install the lighting device.
The lighting device of the invention uses UV illumination to fluoresce a feature of the object and to create contrast, so that it can be properly inspected, for example by a camera, which may in particular comprise a Machine Vision or Automatic Identification software.
The lighting device of the invention creates uniform lighting that can illuminate complex features on objects perfectly, such as shiny objects, comprising for example glass, metals or shiny plastics, with objects that are highly reflective, or with objects that are subject to shadowing with direct or low angle light sources, or with objects that have some very uneven surfaces. The lighting device is appropriate for illuminating every type of surface, from matte to highly reflective.
The object may be a packaging of a luxury good, such as for example tobacco, perfume, spirits, water, milk, the list being not limited.
The feature to be controlled on the object may be a feature which can be fluoresced under UV illumination. It can be glue, with presence or absence inspection, or inks or fibers, for UV codes for example.

Housing

The housing may be in the shape of a dome, with the housing opening at the base of the dome and the control window at the upper part of the dome. Such housing in the shape of a dome may enable to help providing contrast.
The inner wall of the housing also defines the same housing opening at the base of the dome and control window at the upper part of the dome.
A base of the housing may have a substantially square shape.
A base of the inner wall may have a substantially circular shape, which may be inscribed in the square of the housing. The inner wall may have the shape of a hemisphere, with the control window at its top, and the housing opening at its base.
There may be a space between the inner wall of the housing and the outer wall of the housing, in particular in the angles of the squared outer wall.
There may also be a space between the two inner and outer walls all around the housing, particularly due to tolerances.
The housing may comprise an outer wall, which may be made of plastic material. The plastic material may be crossed by the ultraviolet light, while the metal, in particular aluminium, may reflect ultraviolet light.
Said inner wall of the housing may comprise metal, in particular aluminium. The inner wall may be made entirely of metal, in particular aluminium. Aluminium may be advantageously easy to manufacture.
Said inner wall may comprise an upper part around the control window configured for improving the contrast of the illuminated object. Said upper part around the control window may enable to obtain good contrast in the camera.
Said inner wall of the housing may comprise an inner coating at an upper part of the inner wall, which may comprise anodised aluminium, in particular black anodised aluminium.
A size of said upper part may be chosen in order to obtain most brightness in term of reflection. A maximal diameter of said upper part may be slightly larger than the dimension of the housing opening to around 50% of this..
The housing may be configured in such a manner that the at least one light source may illuminate the object by reflexion on the inner wall of the housing, in particular on the upper part of the inner wall. The upper part of the inner wall will help create white on black contrast for all fluorescing objects in the field of view, in particular for objects with shiny or mirrored surface, such as metal or glass.
Aluminium is advantageously easy to anodise.

Light sources

The light sources may be distributed along the periphery of the housing opening. The light sources may be regularly distributed around the housing opening. The light sources may be arranged in a circle.
The at least one light source may be configured to emit one, two and/or three different ultraviolet wavelengths, in particular wavelengths comprised between 355 and 405 nm, for example chosen from the following list: 365 nm, 395 nm, 405 nm, at the peak.
The lighting device of the invention may advantageously integrate a full lighting and filter solution into a single object. It may feature several wavelengths to ensure the fluorescence of features across the 355 to 405 nm range, as this is often unknown by the end user.
As the UV features of the object can fluoresce under different wavelengths, the device has advantageously multiple wavelengths embedded to cover several applications.
The at least one light source may comprise a plurality of light emitting diodes (LED), in particular emitting each at a wavelength comprised between 365 and 405 nm, for example chosen from the following list: 365 nm, 395 nm, 405 nm. The device may comprise at least three different types of LEDs. The device may also comprise bi-colour LEDs.
The device may be configured for enabling to choose between a plurality of modes differing by the wavelengths of the at least one light source.
In an embodiment, the lighting device comprises three modes.
In an embodiment, the lighting device may be configured for enabling the lighting with one wavelength alone, for example 365 nm, or with two wavelengths, for example 395 nm and 405 nm, or with three wavelengths, for example 365 nm and 395 nm and 405 nm.
The at least one light source may be configured to emit visible light, in particular white light. The device may comprise at least four different types of LEDs, among them at least one type of LEDs for the visible light, and one, two or three types of LEDs for the ultraviolet light. In an embodiment, the lighting device comprises an additional mode for choosing white light. The lighting device of the invention may advantageously also include white light for secondary applications with the same lighting device, such as presence/absence of the object.

Control button

The lighting device may also comprise a control button for choosing an appropriate mode among a plurality of modes. The control button may enable to choose one or a plurality of wavelengths to be emitted by the light sources.
The control button may be covered by a removable cap. Said removable cap may be held by a flexible band, which flexible band may be folded when the removable cap is in position on the control button.
The control button may be connected to a printed circuit board (PCB) disposed at the base of the control button.
The control button and PCB may be received in a control box adjacent the housing of the device. The control box may also receive indicators of the selected mode. The indicators may be light indicator. The control box may comprise one to four indicators, for example one for each type of light sources of the device, or one for each mode.
The control box may also comprise a UV light warning indication.
The control box may also comprise an On/Off indicator, and a 'strobe' indicator, indicating for example if the lighting is in strobe mode.

Filter

The lighting device may also comprise a filter for filtering the light issued from the illuminated object, in particular a longpass or bandpass filter.
The filter may be placed through the control window. Such configuration enables to block a part of the light issued from the illuminated object before it enters a camera.
Said filter may be configured for blocking the ultraviolet light, in particular under 400 nm, preferably under 415 nm, or even under 420 nm.
In an embodiment, such filter is configured for allowing only visible light, in particular fluoresced light, to pass therethrough, toward a camera.
The filter of the invention enables to create increased contrast in the images, which makes the machine vision software work better.
The filter enables to block all the visible UV light and only see the part that is fluorescing in the image, which is typically blue or green, typically above 415 nm. The lighting device of the invention may advantageously ensure safety for people in the area by blocking any direct UV radiation to people in the area whilst also providing a simple illumination pattern that is easy to integrate and pair with a camera due to the integrated longpass filter.
The lighting device may comprise a first filter, which may be a longpass filter, and may comprise a second filter, which may be a bandpass filter.

Control device

The invention also provides a control device comprising a lighting device as described above, and a camera to capture the light emitted by the illuminated object through the lighting device.
The camera may capture the light through the control window. The camera may in particular be placed just above the control window.
The camera may be configured for processing the image captured trough the control window, which may comprise a code or other feature of the object, in particular through machine vision or ID software.
A "light source" is an electrical source able to emit radiation in the visible, infrared or ultraviolet range.
The terms "comprise", "contain" and "present" must be interpreted broadly and without limitation unless specified otherwise.

Brief Description of the Figures

Further characteristics and advantages of the invention will appear from reading the detailed description below and from examination of the drawing, in which:

[Fig 1] Figure 1 depicts schematically, in perspective, a control device according to the invention.
[Fig 2] Figure 2 depicts schematically a median cross-section through the device from figure 1.
[Fig 3] Figure 3 depicts schematically, in perspective, the lighting device from figure 1.
[Fig 4] Figure 4 depicts schematically, in perspective, the lighting device from figure 1.
[Fig 5] Figure 5 depicts schematically, in perspective, a half-cut of the lighting device from figure 1.
[Fig 6] Figure 6 depicts schematically, in perspective, a half-cut of the lighting device from figure 1.
[Fig 7] Figure 7 depicts schematically, in perspective, a half-cut of the lighting device from figure 1.
[Fig 8] Figure 8 depicts schematically, in perspective, a half-cut of a detail of the lighting device from figure 1.
[Fig 9] Figure 9 depicts schematically a median cross-section through a detail of the lighting device from figure 1.

Detailed Description

In the various figures, identical references are used to designate identical or similar elements.
Figures 1 to 9 depict a control device 1 according to a preferred embodiment of the invention. This control device 1 comprises a lighting device 10 and a camera 5 to capture the light emitted by an illuminated object O illuminated by the lighting device 10.
The object O may be a packaging of a luxury good, such as for example tobacco, perfume, spirits, water, milk, the list being not limited. The object comprises a feature F to be controlled on the object, which feature can be fluoresced under UV illumination. It can be glue, or inks, for UV codes for example.
The lighting device of the invention uses a UV illumination to fluoresce the feature F of the object O, and to create contrast, so the camera 5 can properly inspect it.
To this aim, the lighting device 10 comprises light sources 20 for illuminating the object O, said light sources 20 being configured to emit ultraviolet wavelength.
The lighting device 10 also comprises a housing 30 containing the light sources, with a housing opening 32 for receiving the object O to be illuminated, and a control window 34 for enabling the visualization of the object O illuminated by the light sources. The control window 34 is opposite the housing opening 32.
The camera 5 is placed to capture the light through the control window 32. The camera 5 may in particular be placed just above the control window 32, as shown on figure 1. In an embodiment, the camera is almost touching the lighting device 10.
The housing 30 is in the shape of a dome, with the housing opening 32 at the base of the dome and the control window 34 at the upper part of the dome.
The housing further comprises an inner wall 36 configured for reflecting the light emitted by the light sources toward the object O to be illuminated, and an outer wall 38. Thanks to the inner wall 36, the object O is advantageously illuminated with an, homogeneous and diffuse light, as shown on figure 2. The inner wall 36 of the housing also defines the same housing opening 32 at the base of the dome and control window 34 at the upper part of the dome.
Regarding the shape of the housing, a base of the housing has a substantially square shape, while a base of the inner wall has a substantially circular shape, which may be inscribed in the square of the housing, as shown on figures 3 to 7. The inner wall has the shape of a hemisphere, with the control window 34 at its top, and the housing opening 32 at its base.
Given the shape of the inner and outer walls, there is a space 40 between the inner wall 36 of the housing and the outer wall 38 of the housing, in particular in the angles of the squared outer wall, as shown on figure 6.
The outer wall 38 of the housing 30 is made of plastic material, which may be crossed by the ultraviolet light, while the inner wall 36 is made entirely of aluminium, which may reflect ultraviolet light.
Furthermore, the inner wall 36 comprises an upper part 36a around the control window 34 configured for improving the contrast of the illuminated object. To this aim, the inner wall 36 the upper part 36a comprises an inner coating at its upper part 36a, which comprises black anodised aluminium. Said upper part 36a around the control window 34 enables to obtain good contrast in the camera 5 for all fluorescing objects O in the camera's field of view, in particular for objects with shiny or mirrored surface, such as metal or glass.
A maximal diameter D of said upper part may be slightly larger than the dimension of the housing opening to around 50% of this, or even greater.
The lighting device 10 further comprises a filter 42 for filtering the light generated from the illuminated object O, which passes through the control window 34. Such configuration enables to block a part of the light issued from the illuminated object, before it enters the camera 5, and more particularly the ultraviolet light, for example under 415 nm. The filter 42 is a longpass filter. The filter 42 is configured for allowing only visible light, in particular fluoresced light, to pass therethrough, toward the camera 5, which is advantageous for increasing contrast in the images, and for safety reason.
As an option, a second filter, which may be a bandpass filter, may be placed on top the first longpass filter.
The light sources 20 are distributed along the periphery of the housing opening 32, being arranged in a circle, as shown on figure 7.
In this exemplary embodiment, the light sources 20 are configured to emit three different ultraviolet wavelengths comprised between 355 and 405 nm, in particular 365 nm, 395 nm, and 405 nm. The light sources are light emitting diodes (LED), emitting each at one or two wavelengths between 355 and 405 nm, in particular 365 nm, 395 nm, and/or 405 nm.
The lighting device 10 is configured for enabling to choose between three UV modes differing by the wavelengths emitted by the light sources 20. In this exemplary embodiment, the lighting device is configured for enabling the lighting with one wavelength alone, for example 365 nm, or with two wavelengths, for example 395 nm and 405 nm, or with three wavelengths, for example 365 nm and 395 nm and 405 nm.
Furthermore, the light sources are configured to emit visible light, in particular white light. The lighting device comprises an additional mode for choosing white light.
The choice of the wavelengths can be made by the user through a control box 50 adjacent the housing 30 of the device 10, thanks to a control button 52, as shown on figure 8 and 9. The outer wall 38 and control box 50 may be one-piece.
The control button 52 enables to choose one or a plurality of wavelengths to be emitted by the light sources. The choice may be seen by the user through 4 light indicators 53 of the selected mode.
The control button 52 is placed at the end of a channel, comprising a removable cap 56. Said removable cap 56 is held by a flexible band 57, which flexible band may be folded when the removable cap is in position on the control button, as shown on figure 3.
Furthermore, the control button is connected to a printed circuit board 55 (PCB) disposed at the base of the control button. The control button and PCB are contained in the control box 50.
The control box also comprises a UV light warning indication 59. The control box also comprises an 'on/off' indicator 61 and a 'strobe' indicator 62, indicating for example if the lighting is in strobe mode.

Claims

Lighting device (10) for illuminating an object (O) to be controlled, comprising:
- at least one light source (20) for illuminating the object (O), said light source (20) being configured to emit at least one ultraviolet wavelength,

- a housing (30) containing the at least one light source (20) and comprising a housing opening (32) for receiving the object to be illuminated, and a control window (34) for enabling the visualization of the object (O) illuminated by the at least one light source (20), said housing (30) comprising an inner wall (36) configured for reflecting the light emitted by said at least one light source (20) toward the object (O) to be illuminated.
Lighting device according to the preceding claim, said housing (30) being in the shape of a dome, with the housing opening (32) at the base of the dome and the control window (34) at the upper part of the dome.
Lighting device according to any preceding claim, said inner wall (36) of the housing comprising metal, in particular aluminium.
Lighting device according to any preceding claim, said inner wall (36) comprising an upper part (36a) around the control window (34) configured for improving the contrast of the illuminated object (O).
Lighting device according to the preceding claim, said inner wall (36) of the housing comprising an inner coating at an upper part (36a) of the inner wall, which may comprise anodised aluminium, in particular black anodised aluminium.
Lighting device according to any preceding claim, comprising light sources (20) which are distributed along the periphery of the housing opening (32).
Lighting device according to any preceding claim, the at least one light source (20) being configured to emit one, two and/or three different ultraviolet wavelengths, in particular wavelengths comprised between 355 and 405 nm, for example chosen from the following list: 365 nm, 395 nm, 405 nm.
Lighting device according to any preceding claim, the at least one light source (20) comprising a plurality of light emitting diodes, in particular emitting each at a wavelength comprised between 355 and 405 nm, for example chosen from the following list: 365 nm, 395 nm, 405 nm.
Lighting device according to any preceding claim, the device (10) being configured for enabling to choose between a plurality of modes differing by the wavelengths of the at least one light source.
Lighting device according to any preceding claim, the at least one light source (20) being configured to emit visible light, in particular white light.
Lighting device according to any preceding claim, comprising a control button (52) for choosing an appropriate mode among a plurality of modes.
Lighting device according to the preceding claim, the control button (52) being covered by a removable cap (56).
Lighting device according to any preceding claim, comprising a filter (42) for filtering the light issued from the illuminated object, in particular a longpass or bandpass filter.
Lighting device according to the preceding claim, said filter (42) being configured for blocking the ultraviolet light, in particular under 400 nm, preferably under 415 nm, more preferably under 420 nm.
Control device (1) comprising a lighting device (10) according to any preceding claim, and a camera (5) to capture the light emitted by the illuminated object (O) through the lighting device (10).