Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C25/00—Apparatus or tools adapted for mounting, removing or inspecting tyres
  • B60C25/002—Inspecting tyres
  • B60C25/007—Inspecting tyres outside surface
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/84—Systems specially adapted for particular applications
  • G01N21/88—Investigating the presence of flaws or contamination
  • G01N21/8806—Specially adapted optical and illumination features
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06V—IMAGE OR VIDEO RECOGNITION OR UNDERSTANDING
  • G06V10/00—Arrangements for image or video recognition or understanding
  • G06V10/10—Image acquisition
  • G06V10/12—Details of acquisition arrangements; Constructional details thereof
  • G06V10/14—Optical characteristics of the device performing the acquisition or on the illumination arrangements
  • G06V10/145—Illumination specially adapted for pattern recognition, e.g. using gratings
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/105—Controlling the light source in response to determined parameters
  • H05B47/11—Controlling the light source in response to determined parameters by determining the brightness or colour temperature of ambient light
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/105—Controlling the light source in response to determined parameters
  • H05B47/115—Controlling the light source in response to determined parameters by determining the presence or movement of objects or living beings
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/155—Coordinated control of two or more light sources
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
  • H05B47/10—Controlling the light source
  • H05B47/16—Controlling the light source by timing means

Definitions

• the present invention relates to the field of visual control, and more particularly the visual control of objects in an industrial environment.
• One of the objects of the present invention relates to a lighting device making it possible to facilitate the visual control of an object to be controlled, such an object being able for example to move on a production line.
• the present invention will find many advantageous applications in industry, and in particular the automobile industry, to facilitate the visual inspection of objects to be inspected such as, for example, the tires of a motor vehicle.
• production line within the meaning of the present invention, is meant throughout the following description a line (or chain) comprising all or part of the manufacturing operations necessary for the production of a manufactured product.
• the products being manufactured will therefore move on this production line from one station to another via a conveyor, conveyor belt or equivalent.
• the tires of a vehicle constitute an important safety element: the tires notably ensure that the vehicle holds well on the road, whatever the weather and road conditions.
• a tire conventionally has a cylindrical structure with a tread intended to be in contact with the road and support sidewalls on either side of the tread.
• the supporting sidewalls generally present information which is used to identify the tire. We will talk in the following about the tire code.
• the tire code constitutes the identity card of the tire and makes it possible to provide relevant information on the manufacturing history of the tire such as for example the name of the manufacturer having manufactured the tyre, the place of manufacture, the serial number and/or the date of manufacture of the tyre.
• this tire code may comprise, according to American regulations, an alphanumeric code comprising letters (for example DOT or VIN) followed by twelve alphanumeric characters formed in relief in the sidewall of the tire.
• this alphanumeric code is most often in the form of molded raised characters or molded inserts.
• the document WO2017074759 teaches a tire code reader in the form of a laser detection device allowing an operator to scan the tire in order to capture an image of the tire code and to download this image via a Wi-Fi® type wireless connection to a “cloud” type cloud server which includes optical character recognition (OCR) means for reading the code from the image received.
• OCR optical character recognition
• This publication proposes a system comprising two cameras arranged on either side of the wheel and a light reflector.
• the Applicant submits that it is not possible to use flashes in an industrial environment, in order to protect the health of operators working on the production site. These flashes generate stress in the operators as well as visual disturbances, which cause both physical and nervous fatigue.
• This synchronization between the flashes and the cameras is moreover complex and requires significant computing resources.
• the present invention aims to improve the situation described above
• the present invention aims in particular to remedy at least one of the various technical problems mentioned above by proposing an innovative lighting solution making it possible to dynamically illuminate the surface of an object to be inspected in an environment such as, for example, a poorly or poorly lit environment, in order to facilitate the capture of images of this surface and to improve the readability and/or the highlighting of the elements (essential or not ) images of this surface.
• the object of the present invention relates, according to a first aspect, to a device for illuminating a surface to be controlled.
• the lighting device comprises at least two light sources each oriented in the direction of a surface to be controlled, each of the sources light being capable of illuminating the surface to be controlled according to a light intensity that varies over time.
• the lighting device further comprises a control unit, such as for example a processor or a microcontroller, configured to dynamically control the light intensity of each of the light sources so that each light source illuminates the surface to be controlled according to an intensity according to a continuous periodic signal.
• a control unit such as for example a processor or a microcontroller, configured to dynamically control the light intensity of each of the light sources so that each light source illuminates the surface to be controlled according to an intensity according to a continuous periodic signal.
• characteristic of the present invention it becomes possible to obtain dynamic lighting of the surface to be controlled, such finely adjusted lighting causing neither reflection nor shadow which could prevent the legibility of characters.
• Such a combination makes it possible to make the relief elements of a surface visible from different directions over time. Each relief element (character, roughness) is thus revealed and highlighted by the lighting in at least one direction.
• Such lighting on the sidewalls of tires makes it possible, for example, to overcome the difficulties relating in particular to the low contrast of the black-on-black inscriptions and the low relief of the characters molded on the sidewalls.
• the continuous periodic signal of each of the light sources is of the sinusoidal type or else of the triangle type.
• the signals from each of the light sources are out of phase with each other.
• the signals from each of the light sources are out of phase with each other according to a phase shift of 2p/N radians.
• the light intensity of each light source is therefore controlled according to a continuous periodic signal with a phase shift of 2p/N radians.
• the light intensity can be controlled according to a sinusoidal or triangle signal with a phase shift of 2p /3 radians between the first and second sources and a phase shift of 4p/3 radians between the first and third sources.
• the signals from each of the light sources have the same oscillation frequency.
• the oscillation frequency is less than or equal to 1Hz.
• the light sources are arranged regularly around the surface to be checked; that is to say spaced at regular intervals.
• each of the light sources is configured to emit light in the direction of the surface to be inspected along a determined optical axis.
• the optical axes of the light sources are substantially concurrent.
• the point of convergence of the optical axes is substantially coincident with the center of the surface to be inspected.
• the light sources are arranged together around the surface to be checked so that the optical axes of two adjacent light sources form in orthogonal projection on the ground an angle a substantially between 35 and 55°, preferably substantially equal to 45°.
• the device according to the present invention comprises three light sources including a first, a second and a third light source, said second source being surrounded by the first and third sources.
• the second source is arranged relative to the surface to be controlled by a first separation distance l ⁇ substantially between 500 and 1500 millimeters, and the first and third sources are arranged relative to the surface to be controlled by a second separation distance l2 substantially between 1000 and 1500 millimeters.
• the first and third sources are placed on the ground (or close to it) and the second source is positioned at a height m with respect to on the ground substantially equal to the first separation distance l ⁇ .
• the first and third sources are inclined and each form with a vertical axis an angle of inclination b substantially between 35 and 55°, preferably substantially equal to 45°.
• the optical axis of the second light source is inclined so that the second source emits in the direction of the surface to be checked at an angle of incidence g between 30 and 60°.
• the lighting device according to the present invention comprises, for each light source, a support comprising adjustment means configured to adjust the position and orientation of each of the sources.
• the light sources are of the incandescent lamp type or of the LED type (for example an LED strip).
• the light sources are configured to emit at different wavelengths.
• the light sources are configured to emit white light.
• the light sources are configured to emit in the infrared.
• the lighting device comprises at least one presence sensor configured to detect a presence in the environment of the surface to be controlled and to generate a presence signal intended for the control unit to control the actuation of light sources.
• the object of the present invention relates, according to a second aspect, to a system for visual inspection of an object comprising a surface to be inspected, said system comprising:
• the at least one camera is configured to capture an image of the surface to be inspected according to an acquisition frequency higher than the oscillation frequency of the light sources.
• the oscillation frequency of the light sources is less than or equal to 1 Hz and the acquisition frequency is greater than or equal to 5 Hz.
• the object of the present invention relates, according to a third aspect, to the use of a visual control system as described above to control an object moving on a production line, said object having a surface to be controlled.
• the object is a tire of a motor vehicle.
• FIG. 1 represents a schematic view of a system for the visual inspection of a tire of an automotive type vehicle moving on a production line, such a system integrating a lighting device according to an embodiment of the present invention.
• FIG. 2 represents a schematic top view of a lighting device according to an exemplary embodiment of the present invention.
• FIG. 3 represents a schematic front view of a lighting device according to an exemplary embodiment of the present invention.
• Figure 4 shows a schematic cross-sectional view of the central light source according to Figure 3.
• FIG. 5 is a graph representative of the signals from the light sources according to an exemplary embodiment.
• FIGS. 1 and 5 A device for illuminating a surface to be inspected according to an embodiment of the present invention as well as a visual inspection system comprising such a device will now be described in the following with reference jointly to FIGS. 1 and 5.
• a visual inspection system comprising such a device
• LP tires have a sidewall on which appears a tire code formed by characters molded in the rubber.
• This lateral flank constitutes a surface S of which at least one image should be captured by an image capture module 30 comprising a plurality of cameras C1, C2 and C3.
• the images acquired by this module 30 therefore include all or part of the pneumatic code which can then be processed by image processing algorithms of the OCR type or equivalent.
• the concept underlying the present invention is the implementation of a visual control system 200 comprising an image capture module 30 coupled to an innovative lighting device 100 which will illuminate this surface S taking into consideration constraints related to the health of operators on the production line, all with a minimum of electrical energy; such a lighting device 100 also enables the capture of sharp images, thus limiting the risk of error in reading and recognizing the code.
• such a lighting device 100 comprises a lighting module 10 comprising three light sources SI, S2 and S3 including a first SI, a second S2 and a third S3 light sources.
• each light source is a source of LED type (LED strip) capable of emitting white light (in the visible spectrum).
• the orientation and position of the light sources S1, S2 and S3 in space makes it possible to significantly improve the performance of the lighting obtained. These are preferably made according to the tires P on the production line LP. It is also possible to provide for this purpose adjustment means (not shown here) arranged to allow adjustment of the height, position and/or orientation of the light sources S1, S2 and S3.
• each of the light sources S1, S2 and S3 is arranged regularly around the surface to be checked S of the tire P (that is to say the lateral side of the latter).
• the light sources S1, S2 and S3 each have an optical axis Al, A2 and A3 respectively.
• the light sources SI, S2 and S3 are configured to emit light along the optical axes Al, A2 and A3 respectively, such axes here being directed in the direction of the surface to be checked S.
• the light sources SI S2 and S3 are arranged between them around the surface S to be controlled so that the second source S2 is surrounded by the first S 1 and third S 3 sources.
• the pairs of the optical axes (Al, A2) and (A2, A3) respectively of the adjacent light sources (SI, S2) and (S2 , S3) form in projection orthogonal to the ground T an angle a substantially between 35 and 55°, preferably substantially equal to 45° (FIG. 2).
• This arrangement of the light sources S1, S2 and S3 proves to be particularly advantageous and allows good lighting.
• the second source S2 (that is to say the central source surrounded by the two peripheral sources) is arranged with respect to the surface to be controlled S by a first separation distance l ⁇ substantially between 500 and 1500 millimeters;
• the first SI and third S3 sources are arranged with respect to this surface to be controlled S by a second separation distance l2 substantially between 1000 and 1500 millimeters.
• the first SI and third S3 sources are placed on the ground T (or close to it);
• the second source S2 is positioned at a height m relative to the ground T substantially equal to the first separation distance l ⁇ .
• first S1 and third S3 sources are inclined and each form with a vertical axis an angle of inclination b substantially between 35 and 55°, preferably substantially equal to 45 °.
• the optical axis A2 of the second light source S2 is inclined so that the second source S2 emits in the direction of the surface to be checked at an angle of incidence g between 30 and 60°.
• the concept underlying the present invention is to provide light sources S1, S2 and S3 which emit light whose intensity is variable over time, each of the sources being controlled synchronously by a control unit 20.
• Such a control unit 20 can take the form of a processor or a microcontroller of the CPU, GPU, TPU, FPGA, etc. type, for example.
• the control of the sources S1, S2 and S3 by the control unit 20 is carried out so as to dynamically illuminate the surface S to be controlled under different directions.
• the light trajectory of each source is a continuous periodic signal such as for example a sinusoidal signal or a triangle signal.
• the three light sources SI, S2 and S3 are driven in a sinusoidal signal with a phase shift of 2p/3 radians from the source S2 with respect to the source SI and of 4p/3 radians of the S3 source with respect to the SI source (light three-phase).
• the signals from each of the light sources S1, S2 and S3 have the same oscillation frequency which is substantially equal to or less than 1Hz.
• the continuous nature of the light signals emitted and the low oscillation frequency (less than or equal to 1Hz) makes it possible to reduce the discomfort caused by the effects of light flashes for operators moving on the production line.
• the cameras C1, C2 and C3 can capture one or more images, see a video stream, containing the illuminated surface S in different directions.
• Each element of relief (character, roughness) is thus revealed and highlighted by the lighting on at least one image.
• the period of the signals is preferably set smaller than the time of presence of the tire moving past the field of vision of the cameras. This makes it possible to have all the lighting directions captured at least once.
• these images are recorded on electronic storage means 40 of the volatile at/or non-volatile memory type and/or on a storage device memory which may include volatile and/or non-volatile memory, such as EEPROM, ROM, PROM, RAM, DRAM, SRAM, flash, magnetic or optical disk.
• volatile and/or non-volatile memory such as EEPROM, ROM, PROM, RAM, DRAM, SRAM, flash, magnetic or optical disk.
• these images are then sent to a remote type server or in the clouds (not shown here) or a communication terminal (not shown here) comprising image processing means capable of process these images or this video stream to detect and recognize the characters appearing on the surface of the tire
• the frequency of acquisition (framerate) of the cameras is greater than the frequency of oscillation of the light sources, this makes it possible to sample more finely the instantaneous resulting direction of the light.
• the acquisition frequency of the cameras C1, C2 and C3 is greater than or equal to 5 Hz.
• At least one presence sensor to detect the arrival of the tires so that the control unit 20 actuates the light sources SI , S2 and S3 only if the presence of a vehicle V is detected.
• the present invention thus provides visual inspection actors with a simple tool to implement taking into account the working conditions of the operators and taking into account the continuous evolution of the resulting direction of the light to make visible/measurable the elements in relief, from a small number of light sources.
• the present invention combines the regular arrangement of the light sources around the surface to be controlled and the use of a continuous periodic signal to dynamically and synchronously control the light intensity of these sources.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Artificial Intelligence (AREA)
• Computer Vision & Pattern Recognition (AREA)
• Multimedia (AREA)
• Theoretical Computer Science (AREA)
• Mechanical Engineering (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
• Circuit Arrangement For Electric Light Sources In General (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=76375218

Family Applications (1)

Country Status (4)

Family Cites Families (5)

• 2021
  • 2021-04-19 FR FR2104018A patent/FR3122008B1/fr active Active
• 2022
  • 2022-04-13 WO PCT/FR2022/050699 patent/WO2022223908A1/fr active Application Filing
  • 2022-04-13 EP EP22723160.2A patent/EP4327295A1/de active Pending
  • 2022-04-13 KR KR1020237034575A patent/KR20230173095A/ko unknown

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