METHOD AND DEVICE FOR INSPECTING LINEARLY MOVING CONTAINERS

Description

Technical Field

[0001] The present invention relates to the technical field of online inspection of transparent or translucent containers such as, for example, glass bottles or flasks, to determine characteristics presented by such containers for the purpose of their quality control.

[0002] The object of the invention finds particularly advantageous but not exclusive applications for controlling or evaluating dimensional characteristics of containers and / or for observing or analyzing optical singularities on the surface or in the wall of a container, such as defects absorbing and / or refracting and / or reflecting light affecting the quality of such containers. Previous technique

[0003] In the prior art, it is known to automatically inspect, on the production line, containers moving at high speed past an optical inspection station comprising a vision system with a light source located on one side of the container and at least one camera located on the other side. The camera captures images of the containers using the light passing through them, which are then analyzed to determine their dimensional characteristics or to detect the presence of defects.

[0004] For example, French patent FR 2 775 079 describes a machine for inspecting the walls and profiles of containers transported in a line by a conveyor. This machine comprises a first inspection station which, using a camera and mirrors, acquires two 60° views, in other words, two images of the containers from two different viewing directions with a 60° angle between them. This machine also comprises a second inspection station, symmetrical to the first station with respect to the conveyor, and comprising a first camera that inspects the wall in two 60° views and a second, superimposed camera that inspects the profile of the containers in two 60° views. It is possible that at the second station, a single camera successively acquires the views for wall inspection and profile analysis.

[0005] Each view is associated with a controlled light source comprising vertical rows of light-emitting diodes. A subtly curved or coiled diffuser intercepts the light from the two light sources at each inspection station, thus diffusing the light and substantially eliminating the dark space between the two light sources.

[0006] This patent teaches how to detect dimensional defects by analyzing profiles by measuring two diameters along two observation directions at 60°. However, since the flat section of a container is not circular, these two measurements do not guarantee good dimensional control of the containers.

[0007] For appearance control, the side of the container located near an edge of the light source panels appears dark, as shown in the figure 3 Consequently, the two sides of the container are not viewed in the same way. However, shadows are areas where detecting defects such as bubbles or inclusions is difficult or even impossible. In other words, detection sensitivity depends on the container's orientation as it passes through the inspection stations. A defect will be seen differently, or even not at all, depending on whether it is located on the container near the wall closest to the edge of the source panel, or near the wall closest to the junction between the two sources. Therefore, this solution does not meet inspection quality requirements.

[0008] Furthermore, this patent teaches how to control the profiles of containers with narrow illuminated areas to obtain very marked shadows on the views.

[0009] Patent application EP3088873 describes an optical inspection device for containers moved by a conveyor. According to a variant illustrated in the drawings, the device comprises a first inspection station equipped, on one side of the conveyor, with three angularly offset light source panels and, on the other side of the conveyor, with three cameras whose viewing directions are centered on the three light source panels. The inspection device includes a second inspection station that is symmetrical to the first inspection station with respect to the conveyor. The three light source panels can be considered as a single panel.

[0010] It should be noted that some panels may be flat in nature, but a panel is not necessarily flat but may be curved or formed from a plurality of segments oriented with respect to each other in a non-planar configuration.

[0011] The panel includes multiple light sources configured to illuminate the container. The light sources are individually controlled to adjust the intensity of each. This allows the camera to capture a uniform image without adjusting the placement or configuration of the light sources relative to the camera.

[0012] However, this device presents the same drawback in that the two sides of the container may not be viewed in the same way. A defect will be seen differently, or even not at all, depending on whether it is located on the container near the wall closest to the edge of the source, or near the wall closest to the junction between two source panels. Furthermore, this patent application indicates the possibility of increasing the number of cameras and source panels to increase the number of views of the containers. However, this results in an increased size of such a device, making its implementation on a container production line practically impractical. In this configuration, the number of panels determines the number of possible views.Regarding dimensional control, following the example with three panels in each inspection station, only three diameters are measured using symmetrically opposite views with respect to the conveyor. Description of the invention

[0013] The object of the present invention is therefore to remedy the disadvantages of the prior art by proposing an inspection method for containers moved along a straight trajectory, designed to guarantee a quality of inspection of the containers while limiting the bulk of the device implementing such an inspection technique.

[0014] Another object of the invention is to propose an inspection method for containers moved along a straight trajectory, designed to obtain the same image rendering regardless of the angle of view around the container.

[0015] To achieve such objectives, the method according to the invention relates to an inspection method for containers moved along a conveyor plane with a straight trajectory, the method consisting of a first inspection station: to provide a first light source illuminating the containers along a first side of the trajectory, comprising an emitting surface having a plane of symmetry perpendicular to the trajectory and extending on the one hand, vertically in a direction normal to the conveying plane and on the other hand, over a total angular width, following a concave curve, the emitting surface being composed of a plurality of elementary light sources controlled so as to define at least three lighting zones having at least one identical first lighting configuration;to make available at least three image sensors with total fields of observation and arranged with optical axes of different directions along a second side of the trajectory opposite to the first side, to present each, when acquiring an image of a container present in its total field of observation, a direction of observation passing through the optical center and the central axis of the container, the directions of observation for the at least three image sensors being different straight lines and adapted to recover the light from an associated lighting area;and when a moving container is successively substantially centered on an observation direction of each of the image sensors, to be acquired by each of said image sensors, at least one image of the container illuminated by the associated lighting zone controlled to be switched on successively during the acquisition, presenting at least the first lighting configuration, the elementary light sources of the lighting zones being controlled in such a way that: * the at least three lighting zones associated with the image sensors have identical angular widths; * the at least three lighting zones associated with the image sensors extend with an angular width symmetrical with respect to the corresponding observation direction; * and at least two angularly adjacent lighting zones have a common part of illumination, considering that the two said lighting zones are not illuminated simultaneously.

[0016] According to a preferred embodiment, in a second inspection station located downstream of the first inspection station in the direction of container movement, the process consists of: to provide a second light source illuminating the containers along the second side of the trajectory, comprising an emitting surface having a plane of symmetry perpendicular to the trajectory and extending on the one hand, vertically in a direction normal to the conveying plane and on the other hand, over a total angular width, following a concave curve, the emitting surface being composed of a plurality of elementary light sources controlled so as to define at least three lighting zones having at least one first identical lighting configuration;to make available at least three image sensors with total fields of observation and arranged with optical axes of different directions along the first side of the trajectory, to present each, during an image acquisition of a container present in its total field of observation, a direction of observation passing through the optical center and the central axis of the container, the directions of observation for the at least three image sensors being different straight lines and adapted to recover the light from an associated lighting area;and when a moving container is successively substantially centered on an observation direction of each of the image sensors, to be acquired by each of said image sensors, at least one image of the container illuminated by the associated lighting zone controlled to be switched on successively during the acquisition, presenting at least the first lighting configuration, the elementary light sources of the lighting zones being controlled in such a way that: * the at least three lighting zones associated with the image sensors have identical angular widths; * the at least three lighting zones associated with the image sensors extend with an angular width symmetrical with respect to the corresponding observation direction; * and at least two angularly adjacent lighting zones have a common part of illumination, considering that the two said lighting zones are not illuminated simultaneously.

[0017] According to one embodiment, the first light source and / or the second light source are made available with an emitting surface made by a portion of a generalized cylinder generated by a generatrix made by a vertical straight line segment and a concave directrix curve along the conveying plane, the concavity of which is turned towards the containers.

[0018] For example, the first light source and / or the second light source are made available, each with an emitting surface with a total angular width between 100 and 175°.

[0019] Preferably, the first light source and / or the second light source are made available, each with an emitting surface whose directing curve is an arc of a circle.

[0020] According to one embodiment, the first light source and / or the second light source are provided with an emitting surface having, according to the conveying plan, a width between 500 mm and 700 mm and a depth between 100 mm and 350 mm.

[0021] Typically, the first light source and / or the second light source is made available with an emitting surface made by a backlit, one-piece diffuser.

[0022] According to one implementation variant, in each inspection station: For the emitting surface of each light source, at least three lighting zones are made available, presenting at least the first identical lighting configuration, a second identical lighting configuration, and a third identical lighting configuration; and when a container is substantially centered on an observation direction of an image sensor, each of said image sensors is to acquire successively at least one image of the container illuminated by the associated lighting zone, presenting the first lighting configuration, at least one image of the container illuminated by the associated lighting zone, presenting the second lighting configuration, and at least one image of the container illuminated by the associated lighting zone, presenting the third lighting configuration.

[0023] Typically, at each inspection station, at least three lighting zones are provided for the emitting surface of each light source, featuring: as the first identical lighting configuration, an extended configuration with a suitable homogeneous pattern; as the second identical lighting configuration, a restricted homogeneous configuration; as the third identical lighting configuration, a structured configuration.

[0024] According to one implementation example, at least three image sensors are made available at the first inspection station and at least three image sensors at the second inspection station, said at least six image sensors having at least six observation directions separated from each other in pairs by at least 10°.

[0025] According to another example of implementation: In the first inspection station, at least three image sensors are provided with observation directions spaced two by two at least 30 degrees apart and preferably at least 40° apart; in the second inspection station, at least three image sensors are provided with observation directions spaced two by two at least 30 degrees apart and preferably at least 40° apart.

[0026] For example, the observation directions of the image sensors are modified in number and / or angle values ​​relative to the direction of movement by adapting only the control of the first light source and / or the second light source to present at least three lighting zones with at least one first lighting configuration.

[0027] According to another example, the number of observation directions of image sensors is increased by adding image sensors.

[0028] Advantageously, at least one image sensor acquires at least two images of each container from at least two different viewing directions following the movement of the container within the total viewing field of the image sensor.

[0029] As examples of applications, we perform an analysis of images taken by image sensors with the same configuration of lighting zones to deduce information on defects and / or dimensions of containers.

[0030] For example: We carry out the analysis of the six images taken by the at least six image sensors at at least a given height in the images traversed from the bottom of the container upwards, to determine the distance between two opposite edges of the container in order to deduce a measurement of the diameter of the container at said height, we determine the dimensional conformity of the container from the measurements of at least six different diameters in six different directions compared to diameter tolerance thresholds or non-circularity thresholds for at least a given height of the container.

[0031] According to another advantageous feature, the method consists of providing at least three image sensors in an inspection station, all having a substantially identical working distance at the time of image acquisition under the same lighting configuration.

[0032] According to another advantageous feature, the method consists of providing at least three image sensors in a first inspection station and at least three image sensors in a second inspection station, all having a substantially identical working distance at the time of image acquisition under the same lighting configuration.

[0033] Another object of the invention is to provide an inspection device for containers moved along a conveyor plane with a straight trajectory, this inspection device comprising: * a first inspection station comprising: a first light source along a first side of the trajectory, comprising an emitting surface having a plane of symmetry perpendicular to the trajectory and extending on the one hand, vertically in a direction normal to the conveying plane and on the other hand, over a total angular width following a concave curve, the emitting surface being composed of a plurality of elementary light sources controlled so as to define at least three lighting zones having at least one identical first lighting configuration;at least three image sensors with total fields of view and arranged with optical axes of different directions along a second side of the trajectory opposite to the first side, to present each, when acquiring an image of a container present in its total field of view, a direction of view passing through the optical center and the central axis of the container, the directions of view for the image sensors being different and adapted to recover light from an associated lighting area;*a second inspection station located downstream of the first inspection station according to the direction of movement of the containers, this second inspection station comprising: a second light source along the second side of the trajectory, comprising an emitting surface having a plane of symmetry perpendicular to the trajectory and extending on the one hand, vertically in a direction normal to the conveying plane and on the other hand, over a total angular width, following a concave curve, the emitting surface being composed of a plurality of elementary light sources controlled so as to define at least three lighting zones having at least one first identical lighting configuration;at least three image sensors with total fields of view and arranged with optical axes of different directions along the first side of the trajectory, to present each, when acquiring an image of a container present in its total field of view, a direction of view passing through the optical center and the central axis of the container, the directions of view for the image sensors being adapted to recover light from an associated lighting area, the directions of view for the image sensors of the second inspection station being different straight lines from each other and different from the directions of view of the image sensors of the first inspection station;* and a control system for the light sources and image sensors, configured so that, when a moving container is successively substantially centered on an observation direction, each of the image sensors acquires, by each of said image sensors, at least one image of the container illuminated by the associated lighting zone controlled to be switched on successively during the acquisition, presenting at least the first lighting configuration, the elementary light sources of the lighting zones being controlled so that: the at least three lighting zones of each inspection station associated with the image sensors have identical angular widths; the at least three lighting zones of each inspection station associated with the image sensors extend with an angular width symmetrical with respect to the corresponding observation direction;and at least two angularly adjacent lighting zones for each inspection station, have a common lighting component, assuming that the two said lighting zones are not illuminated simultaneously.

[0034] According to one embodiment feature, the at least three image sensors, of each inspection station have observation directions which are straight lines separated from each other in pairs by at least 30° angle and preferably by at least 40° angle.

[0035] Advantageously, the at least three image sensors of the first station and the at least three image sensors of the second station have at least six observation directions separated from each other in pairs by at least 10°.

[0036] Typically, the first light source and / or the second light source has an emitting surface with, according to the conveying plan, a width between 500 mm and 700 mm and a depth between 100 mm and 350 mm.

[0037] Furthermore, the first light source and the second light source are advantageously positioned so that the emitting surfaces of the light sources have a footprint between 1000 mm and 1400 mm.

[0038] According to a preferred implementation example, the emitting surface of the first light source and / or the second light source is achieved by a backlit, one-piece diffuser.

[0039] According to an advantageous embodiment, at least three image sensors in an inspection station all have a substantially identical working distance taken along the optical axis between their optical center and the trajectory of the containers.

[0040] According to another advantageous embodiment, at least three image sensors in a first inspection station and at least three image sensors in a second inspection station all have a substantially identical working distance taken along the optical axis between their optical center and the trajectory of the containers. Brief description of the drawings

[0041] [ Fig. 1 ] There Figure 1 is a schematic perspective view showing an example of the implementation of a device for inspecting containers moved in translation. Fig. 2 ] There figure 2 is a schematic top view showing an example of an embodiment of an inspection device according to the invention. Fig. 3 ] There figure 3 is a schematic view showing, in the horizontal plane, the illumination zones of the emitting surfaces and the observation fields of the image sensors of the inspection device according to the invention. Fig. 3A ] There figure 3A is a schematic view showing, in the horizontal plane, a first illumination zone of the emitting surface of the first inspection station and the field of view of a first image sensor encountered during the movement of a container. Fig. 3B ] There figure 3B is a schematic view showing, in the horizontal plane, a second illumination zone of the emitting surface of the first inspection station and the observation field of a second image sensor encountered during the movement of a container. Fig. 3C ] There figure 3C is a schematic view showing, in the horizontal plane, a third illumination zone of the emitting surface of the first inspection station and the observation field of a third image sensor encountered during the movement of a container. Fig. 4A ] There figure 4A is a diagram schematically representing the lighting produced when a mass diffuser is divided into two distinct bodies. Fig. 4B ] There figure 4B is a diagram schematically representing the lighting produced when a mass diffuser is made up of a continuous diffuser. Fig. 4C ] There figure 4C is a diagram schematically representing the lighting produced when a surface diffuser is divided into two distinct bodies. Fig. 4D ] There figure 4D is a diagram schematically representing the lighting produced when a surface diffuser is made up of a continuous diffuser. Fig. 5A ] There figure 5A shows two views of containers taken by two adjacent cameras in accordance with the invention. Fig. 5B ] There figure 5B shows two views of containers taken by two adjacent cameras with a plane light source parallel to the trajectory of the containers or with the edge of the light source close to the right side of the container. Fig. 6A ] There figure 6A is a schematic view showing, in the horizontal plane, the position of six image sensors arranged symmetrically according to the two inspection stations and on either side of the trajectory of the containers. Fig. 6B ] There figure 6B is a schematic view showing, in the horizontal plane, the position of the three different diameters of a container as seen by the six image sensors illustrated in the figure 6A . [ Fig. 7A ] There figure 7A is a schematic view showing, in the horizontal plane, the position of six image sensors arranged asymmetrically according to the two inspection stations on either side of the trajectory of the containers. Fig. 7B ] There figure 7B is a schematic view showing, in the horizontal plane, the position of the six different diameters of a container as seen by the six image sensors illustrated in the figure 7A . [ Fig. 8A ] There figure 8A is a schematic view showing, in the horizontal plane, the position of seven image sensors arranged asymmetrically according to the two inspection stations on either side of the trajectory of the containers. Fig. 8B ] There figure 8B is a schematic view showing, in the horizontal plane, the position of the seven different diameters of a container as seen by the seven image sensors illustrated in the figure 8A . [ Fig. 9A ] There figure 9A is a schematic view showing, in the horizontal plane, a so-called homogeneous restricted lighting configuration for a lighting area associated with an image sensor. Fig. 9B ] There figure 9B is a schematic view showing, in the horizontal plane, a homogeneous extended lighting configuration adapted for a lighting area associated with an image sensor. Fig. 9C ] There figure 9C is a schematic view showing, in the horizontal plane, a so-called structured lighting configuration for a lighting area associated with an image sensor. Fig. 10 ] There figure 10 is a schematic view showing, in the horizontal plane, an elliptical configuration of the emitting surface of a light source. Fig. 11 ] There figure 11 is a schematic view showing in the horizontal plane, the angles γ of the light rays coming from the container with respect to the observation direction of an image sensor. Description of the implementation methods

[0042] As shown in particular in Figures 1 and 2, the object of the invention relates to a device I and a method for inline inspection of containers 1 made of transparent or translucent material, such as, for example, glass containers, particularly empty ones. These containers are inspected using image sensors that capture light that has passed through the containers and originates from light sources. The images captured by the analog or digital image sensors are analyzed to ensure quality control, in particular to check or evaluate the dimensional characteristics of the containers and / or to observe or analyze optical singularities on the surface or within the wall of a container. The digital images are analyzed by a computer processing unit of any possible architecture, composed of processors (CPU, GPU, and / or FPGA) and memory distributed across several computers, and means for data acquisition, display, and communication.Optical singularities are defined as small areas of a container or its surface that have properties different from those of their surroundings, either on or within the container. Specifically, these optical singularities primarily have an anomalous effect on transmission, refraction, polarization, and / or reflection compared to their surroundings. Refracting and / or reflecting defects, codes, or even coat-of-arms-like decorations on the surface of containers are therefore optical singularities that deflect light differently from their surroundings, either in transmission (diopters) or reflection.Dirt, foreign bodies, or areas of abnormal thickness are therefore optical singularities that absorb light differently from their surroundings. Certain foreign bodies, creating stress, are thus optical singularities that modify the polarization state of light differently from their surroundings. The object of the invention thus makes it possible, in particular, to detect any defects that absorb, refract, and / or reflect light and affect the quality of such containers.

[0043] Device I comprises at least one first inspection station I1 through which containers 1 are conveyed in a direction F, using a transport system II of any type known per se. According to an illustrated embodiment, device I also comprises a second inspection station I2 located downstream of the first inspection station I1 in the direction F of container movement. Device I may, of course, comprise a single inspection station.

[0044] In general, a container 1 has a central axis A, considered as an axis of symmetry, or even an axis of revolution symmetry. Thus, a container 1 has a glass wall forming, from bottom to top along the central axis A, a base connected to a foot from which rises a body extending into a shoulder connected to a neck or rim ending in a ring delimiting the opening allowing the container to be filled or emptied.

[0045] The central axis A is considered an axis of symmetry for round-section containers, assuming a perfectly uniform and ideal glass distribution relative to the container's design plane. Obviously, actual containers are not strictly symmetrical. The glass distribution is somewhat heterogeneous. Some containers feature embossed decorations or rimmed edges, etc. Finally, many so-called "shaped articles" have a body with a non-round cross-section. In most cases, even for shaped articles, the central axis A corresponds to an axis orthogonal to the plane defining the container's base and parallel to a conveying plane Pc of the containers.

[0046] In at least each of the inspection stations of device I, the containers 1 are transported in a horizontal conveyor plane Pc using the transport system II of any known type. It should be noted that on the production lines as illustrated, upstream and downstream of the various inspection stations I1, I2, the containers 1 are transported bottom-first on pallet or chain conveyors. The surface area of ​​the chain defines the conveyor plane, which is generally horizontal. The containers are sometimes brought to the inspection stations I1, I2 by so-called infeed conveyors and then, after inspection, placed back onto a so-called outfeed conveyor. The infeed and outfeed conveyors generally have the same conveyor plane. This conveyor plane is very generally horizontal, and during conveying, the central axis of the containers resting on their bottoms remains vertical.Transport system II is of all known types in itself provided that the containers are made to move between a light source and an image sensor and that a portion of the wall to be inspected is cleared to allow the passage of light from the light source, to the container and then towards the image sensors.

[0047] In this application, the direction of movement F of the containers 1 is established along a rectilinear trajectory with a horizontal axis X of a direct orthonormal coordinate system X, Y, Z comprising a vertical axis Z perpendicular to the horizontal axis X and a transverse axis Y perpendicular to both the vertical axis Z and the horizontal axis X, and the axes X and Y lying in a plane parallel to a horizontal conveying plane Pc of the containers. The containers 1 are thus moved solely in a rectilinear translation, without any rotation about themselves.

[0048] According to the invention, the first inspection station I1 comprises a first light source L1 arranged along a first side of the X-axis trajectory of the containers, as shown in the figures 2 And 3 This first light source L1 comprises an emitting surface S1 having a plane of symmetry P1 perpendicular to the trajectory along the X-axis of the containers. This emitting surface S1 extends vertically along a Z-axis perpendicular to the conveying plane Pc. This emitting surface S1 also extends over a total angular width along a plane with X, Y axes parallel to the conveying plane Pc, following a concave curve whose concavity faces the transport system II. This total angular width is measured in the conveying plane at a point M located on the trajectory of the central axis A of the containers.

[0049] According to the embodiment illustrated in the drawings, the device I also includes a second inspection station I2 comprising a second light source L2 arranged along the second side of the X-axis trajectory of the containers, i.e., on the opposite side to that equipped with the first light source L1, as shown in the figures 2 And 3This second light source L2 comprises an emitting surface S2 having a plane of symmetry P2 perpendicular to the X-axis trajectory of the containers. This emitting surface S2 extends vertically along a Z-axis perpendicular to the conveying plane Pc. This emitting surface S2 also extends in total angular width along a plane with axes X and Y parallel to the conveying plane Pc, following a concave curve whose concavity faces the transport system II. This total angular width is measured in the conveying plane at a point M located on the trajectory of the central axis A of the containers.

[0050] It must be considered that the emitting surfaces S1 and S2 of the first L1 and second L2 light sources can have different shapes. It should be noted that the emitting surfaces S1 and S2 of the first L1 and second L2 light sources may have identical or different shapes. According to one embodiment, the first light source L1 and / or the second light source L2 has an emitting surface S1, S2 formed by a portion of a generalized cylinder generated by a generatrix formed by a vertical line segment with axis Z and a concave direction curve along the conveying plane Pc, the concavity of which faces the conveying system II.

[0051] Typically, the emitting surface S1, S2 is formed by a portion of a cylinder with a directrix curve approximated by segments, the angles between connected segments being greater than 160°, and / or the segments being connected by edges with a suitable radius of curvature (e.g., greater than 5 mm) to avoid creating horizontal variations in luminance across the surface. A smooth, preferably regular, curve is preferred as the directrix to a curve approximated by segments. The emitting surface S1, S2 of the first and / or second light source can thus be in the form of a portion of a cycloid or a portion of an ellipse, as illustrated in the figure. figure 10 According to one embodiment, the direction curve of the emitting surface of the first light source and / or the second light source is an arc of a circle.

[0052] Advantageously, the first light source L1 and / or the second light source L2 has an emitting surface S1, S2 with a total angular width between 100° and 175°, this total angular width being taken in the plane of axes X, Y, following the curve of the emitting surface, and measured in the conveying plane at a point M located on the path of the central axis A of the containers. According to a preferred embodiment, the first light source L1 and / or the second light source L2 has an emitting surface S1, S2 whose directrix curve is a circular arc with angle θ.

[0053] According to one embodiment, the first light source L1 and / or the second light source L2 has an emitting surface S1, S2 having, along the conveyor plane Pc, a width l along the X-axis between 500 mm and 700 mm and a depth p along the Y-axis between 100 mm and 350 mm. Similarly, the first light source L1 and / or the second light source L2 has an emitting surface S1, S2 having, for example, a height along the Z-axis between 20 mm and 800 mm. Advantageously, the first light source L1 and the second light source L2 are positioned such that the emitting surfaces S1, S2 of the light sources have a footprint L along the X-axis between 1000 mm and 1400 mm. For example, the emitting surfaces S1, S2 of the light sources are positioned so as to be substantially contiguous along the horizontal axis X trajectory.

[0054] According to one feature of the invention, each emitting surface S1, S2 is composed of a plurality of elementary light sources controlled by switching them on and off so as to define at least three lighting zones, respectively S11, S12, S13 and S21, S22, S23, each having at least one identical lighting configuration. It should be understood that an elementary light source corresponds to an elementary portion of the emitting surface S1, S2. These elementary light sources can be implemented in any suitable manner. For example, each elementary light source comprises a primary elementary source Sf that backlights an element of the emitting light surface. In this embodiment, each primary elementary source Sf consists of a light-emitting diode (LED) with a PN junction for emitting light in a specific spectral emission band.In another embodiment, each primary source Sf consists of a light-emitting diode (LED) with several PN junctions or adjacent arrays emitting light in different spectral emission bands. Each array of LEDs is electronically controlled for switching on and off. In yet another embodiment, each primary source Sf comprises several LEDs controlled together.

[0055] According to a preferred embodiment, the emitting surface S1, S2 of the first and / or second light source is formed by a single-piece, backlit diffuser. In other words, the emitting surface S1, S2 is that of a continuous diffuser, either solid or surface-based, colored or uncolored, and adapted to transmit the visible and / or near-infrared spectrum of light. A solid diffuser is a diffuser of a certain thickness, such as, for example, a white and / or translucent polyacrylate sheet curved by thermoforming, with diffusion occurring within its thickness, for example, 2 mm.A surface diffuser, having at least one side with a specific granular surface texture that diffuses the light passing through it, is made, for example, by means of a frosted or molded transparent polyacrylate sheet, then thermoformed to conform to the curvature of the direction curve, or by means of a thin, flexible film curved during assembly. It is possible to superimpose several diffusers and combine them with colored or polarizing filters. In this way, the light E emitted by a region of the emitting surface S1, S2, formed by the diffuser backlit by at least two different contiguous primary light sources Sf, is uniform and shadow-free, as illustrated in Figure 1. figure 4B for a mass differential diffuser and the figure 4D for a surface diffuser. Conversely, the figure 4A for a mass diffuser and the figure 4C For a surface diffuser, the case where two different diffusers dif1, dif2 are juxtaposed is shown. According to these two examples, since the diffusion is interrupted by the edges bdif of the two diffusers dif1, dif2, the boundary would present a visible illumination anomaly Ed on the perceived light profiles E. The continuity of material or surface of the diffuser dif therefore results in continuous illumination without interruption over any area of ​​the emitting surface S1, S2. For example, it is possible to display the same lighting pattern anywhere on the emitting surface S1, S2. It is also possible to shift a lighting pattern up and down and / or from right to left across the entire emitting surface S1, S2, successively by one step, or more precisely by an elementary shift corresponding to the size of the elementary sources, the pattern remaining constant without shadows or interruptions.

[0056] The continuous diffuser dif is positioned in front of the primary elementary sources Sf relative to the transport system II. Thus, the emitting surface S1, S2 is that of a diffuser backlit by the primary elementary sources Sf mounted on one or more printed circuits. For example, the primary elementary sources Sf are mounted on a flexible printed circuit shaped along the concave direction curve or on at least three planar printed circuits forming a polyhedron as in the illustrated example ( figure 1 ). Similarly, elementary light sources are portions of the surface of a diffuser backlit by light-emitting diodes carried by one or more printed circuits and constituting the set of primary elementary sources Sf.

[0057] It is recalled that, by means of the electronic control of the primary light sources Sf, the elementary light sources are independently controlled by switching them on and off in order to define, for each inspection station, at least three lighting zones, respectively S11, S12, S13 and S21, S22, S23, each having at least one identical initial lighting configuration. A lighting zone corresponds to a region of the emitting surface S1, S2 containing a specific set of elementary light sources controlled simultaneously for switching on. Each lighting zone is delimited by a border extending along the vertical axis Z and a concave curve of illumination angular width established in the plane of the axes X, Y.Each lighting zone S11, S12, S13, S21, S22, S23 therefore has an angular width of illumination L11, L12, L13, L21, L22, L23 respectively, measured along the X, Y axis plane. The angle is measured by the angle between two lines intersecting on the central axis A of the container and the two lateral edges of the lighting zone, as shown in the figures. The angular width of illumination is thus the angle at which the light is received by the container. The angular width of a lighting zone is the angular width of a vertical-horizontal rectangle encompassing all the elementary light sources illuminated together within the same lighting zone. The set of elementary light sources illuminated together from the same lighting area can therefore have a non-rectangular contour, for example a contour running along, with a given margin, the silhouette of a container for a direction of observation and an associated image sensor.

[0058] A lighting zone S11, S12, S13 and S21, S22, S23 exhibits an illumination pattern corresponding to the spatial distribution of light intensities generated by the various elementary light sources within that lighting zone. It is also possible that other light properties, such as color, polarization, or temporal phase, may have different spatial distributions within a lighting zone. The lighting pattern of the zones is adapted to the type of quality control to be performed, namely the evaluation of the dimensional characteristics of the containers or the detection of defects that absorb, refract, and / or reflect light or alter its polarization state and affect the quality of such containers.

[0059] The lighting pattern of the illuminated areas can take on various known configurations. One such configuration is called extended with a homogeneous matching pattern. In this configuration, the illuminated area is extended relative to the container's silhouette; specifically, the angular width of the illumination is such that, from the camera's perspective, the illuminated area largely encompasses the container's silhouette. The angular width of the illumination can be such that the edges of the illuminated area are outside the camera's effective field of view. The homogeneous matching pattern is such that the spatial distribution of the generated light intensities is homogeneous within a rectangular or non-rectangular contour of the illuminated area.This spatial distribution exhibits no abrupt changes and is designed so that some regions generate greater light intensity than others, allowing light to penetrate more absorbent areas of the tinted glass containers, such as thicker regions like the neck. This illumination pattern, without strong local variations in intensity, aims to provide images that readily highlight absorbing defects. Its extended size creates narrow shadows on the walls, widening the detection area and improving the overlap between different observations.

[0060] A second lighting configuration is called homogeneous restricted lighting. In this second configuration, the illuminated area is restricted in size, meaning its angular width is narrow to closely follow the container's silhouette from the camera's perspective. Its outline may or may not be rectangular, and the pattern, such as the spatial distribution of generated light intensities, is homogeneous around the container's silhouette without abrupt vertical variations. Transmission matching is not necessary because the purpose of this second lighting configuration is to provide images for dimensional control based on image detection of the container's contours or silhouette, without focusing on the interior of the silhouette. It is even possible for the interior of this area to contain a dark or black portion, but the background of the container's wall contours remains homogeneous.Being narrow, it creates thick shadows on the walls, that is to say, marked shadows, contrasting with the background, very black and extending towards the inside of the silhouette.

[0061] A third lighting configuration, called structured, is generally extended beyond the container's outline, and its lighting pattern is described as structured or target-type. A structured lighting pattern, or target, is defined as a function of spatial variation within the illuminated area of ​​at least one property of light. The spatially variable property is usually light intensity. Alternatively, the spatially variable property is the wavelength spectrum (color) or a polarization property such as the direction of polarization, the sense of circular polarization, or the degree of polarization. Another alternative is the spatially variable property is the shape or phase of a periodic temporal variation of a property of light such as its intensity, polarization state, or emission spectrum.When the pattern is non-uniform, and therefore the lighting area presents a structured lighting pattern or test pattern, the variation can be of any type, such as a slope, a triangle, a step, a succession of slopes, continuous, discontinuous, cyclic or non-cyclic, rapid or slow, vertical or oblique, etc. Preferably, a test pattern with periodic variation is generally used. The spatial variation function can be bidirectional, as when the structured lighting pattern or test pattern takes the form of a checkerboard. The spatial distribution of the generated light intensities exhibits sufficiently rapid variations to contrast with defects that deflect the light, and therefore refracting defects that will transmit light with a variable property different from that transmitted by their surroundings.

[0062] A person skilled in the art will recognize that according to the invention a lighting zone can exhibit any lighting configuration, size, intensity distribution or variation of any property of light for different detection methods from different types of images obtained.

[0063] According to one alternative embodiment, the lighting zones have: The first identical lighting configuration is the extended homogeneous pattern configuration. This first lighting configuration is suitable for detecting, in particular, absorbing or refracting surface defects, also known as stress defects. The second identical lighting configuration is the restricted homogeneous configuration. The illuminated area is uniform within a closed contour with an angular width 40% smaller than the angular width of the first identical configuration, considering that the interior of this area may contain a dark portion, but with the background of the container wall contours being homogeneous.This lighting configuration, which has a reduced illumination width compared to the first configuration, is particularly suitable for dimensional control of containers by producing appropriate shadows on the images at the contours of the containers; as a third identical lighting configuration, the so-called structured configuration. This third lighting configuration is particularly suitable for detecting refracting defects such as folds, bubbles, or reliefs like decorative engravings, positioning lugs, or identification codes.

[0064] By identical lighting configuration, it should be understood that all lighting zones S11, S12, S13 and S21, S22, S23 have an identical illumination pattern. In other words, each container 1 passing through inspection stations I1, I2 is illuminated in the same way for the said image captures, at least once by this illumination pattern.

[0065] The inspection device includes a control system 10 for switching the elementary light sources on and off. This control system 10, of any known type, controls the elementary light sources so that they emit a specific amount of light during image acquisition. Thus, in the embodiment shown, this control system 10 controls the primary elementary sources Sf by the duration of illumination and / or the current and / or the voltage and / or a duty cycle and / or a modulation frequency and / or a time phase shift. As explained above, this control system 10 controls the elementary light sources in such a way as to define, for each emitting surface S1, S2, at least three lighting zones, each with at least one identical initial lighting configuration.

[0066] According to another feature of the invention, the first inspection station I1 comprises at least three image sensors C11, C12, C13 arranged along the second side of the path opposite the first side, on which the first light source L1 is positioned. The image sensors C11, C12, C13 are optical image acquisition systems, each comprising a camera of any type known per se and at least one lens with an optical center. Typically, each image sensor C11, C12, C13 has an optical axis A11, A12, A13 respectively, an optical center O, a total field of view, and a working distance W between the optical center O and the focal plane.The three image sensors C11, C12, C13 are arranged with optical axes of different directions along the second side of the trajectory opposite to the first side, to take images of the containers entering their total field of view during the movement of the containers.

[0067] Although focusing can be done on the front face of the containers, generally the focal plane is such that both sides of the container are sharp in the images, and the focal plane roughly corresponds to the central axis A of the containers. In the following description, the working distance W is defined as the distance between the optical center O of the image sensor and the central axis A of the container at the time of image acquisition, as illustrated in the figure 11 .

[0068] The acquired image includes a complete or partial image of the container. This image corresponds to a useful field of view. The acquired image may, but does not necessarily, have the maximum size allowed by the optoelectronic sensor and the lens focal length. Therefore, the useful field of view may cover the total field of view. The total field of view of each camera is thus greater than or equal to the useful field of view. figures 9A, 9B , 9CThe total field of view of camera C12 is shown as being contained within a total field angle α. It is observed that the useful field is arbitrary as long as it allows for the image of the container or a portion of the container to be inspected. Thus, it would be possible for the useful field to be equal to the total field each time. Alternatively, it is possible that the image sensors transmit only digital images covering a minimum useful field to reduce the amount of data transmitted to the computer processing unit.

[0069] During image acquisition of a container within its full field of view, each image sensor C11, C12, C13 presents a viewing direction D11, D12, D13, passing through the optical center O and the central axis A of container 1. This viewing direction corresponds to the straight line segment connecting the optical center O of the camera lens to the central axis A of container 1, projected onto the horizontal plane along the X and Y axes. Each image sensor C11, C12, C13 presents a specific viewing angle δ corresponding to the angle of the viewing direction D11, D12, D13 relative to the scrolling direction F projected onto the horizontal plane along the X and Y axes. The working distance W of each image sensor is the length of the segment connecting the optical center O of the camera lens to the central axis A of container 1.

[0070] In this description, for the sake of clarity, the observation directions of the image sensors are projected onto the horizontal plane along the X and Y axes, as the angle of the observation directions relative to the conveyor plane Pc is not relevant. This means that the image sensors can observe the containers or present observation directions, regardless of whether they are viewed from above or below, for the purposes of this invention. Similarly, the interdirectional angles β between two observation directions in the horizontal plane along the X and Y axes are defined. By convention, the observation angle δ is the angle measured in the horizontal plane along the X and Y axes, in the trigonometric direction, of an observation direction relative to the conveyor direction F; that is, it corresponds to the angle between the X axis and the segment of the horizontal line connecting the optical center of the camera lens to the central axis A of the container 1.Similarly, the working distances of image sensors can be considered in the horizontal plane of the X and Y axes.

[0071] Furthermore, the observation directions D11, D12, D13 for the at least three image sensors of the first inspection station I1 are distinct straight lines with a pairwise inter-direction angle β, and are adapted to capture light from an associated illumination zone S11, S12, S13. In other words, each image sensor C11, C12, C13 of the first inspection station I1 is adapted to capture light from an associated illumination zone S11, S12, S13, respectively, as is clearly shown in the figures 3A à 3C . Thus, each image sensor C11, C12, C13 and each associated lighting zone S11, S12, S13 respectively are adapted two by two at the time of image acquisitions according to the observation directions D11, D12, D13.

[0072] According to another feature of the invention, the second inspection station I2 comprises at least three image sensors C21, C22, C23 arranged along the first side of the path opposite the second side in which the second light source L2 is positioned. The image sensors C21, C22, C23 are optical image acquisition systems, each comprising a camera of any type known per se and at least one lens with an optical center O. Conventionally, each image sensor C21, C22, C23 of the second inspection station has an optical axis A21, A22, A23 respectively, an optical center O, a total field of view, and a working distance W between the optical center O and the focal plane.The three image sensors C21, C22, C23 are arranged with optical axes in different directions, along the first side of the trajectory opposite the second side, to take images of the containers entering their total field of view during the movement of the containers.

[0073] As previously stated, the working distance W is the distance between the optical center O of the image sensor and the central axis A of the container at the time of image acquisition. Similarly, the total field of view of a camera is contained within a total field angle α. The total field of view of each camera is greater than or equal to the useful field of view required to capture the image of the container or a portion of the container to be inspected.

[0074] During image acquisition of a container within its full field of view, each image sensor C21, C22, C23 presents a viewing direction D21, D22, D23, passing through the optical center O and the central axis A of container 1. This viewing direction corresponds to the straight line segment connecting the optical center O of the camera lens and the central axis A of container 1, projected onto the horizontal plane along the X and Y axes. Each image sensor C21, C22, C23 presents a specific viewing angle δ corresponding to the angle of the viewing direction D21, D22, D23 relative to the scrolling direction F projected onto the horizontal plane along the X and Y axes. The working distance W of each image sensor is the length of the segment connecting the optical center O of the lens to the central axis A of container 1.

[0075] Furthermore, the observation directions D21, D22, and D23 for the at least three image sensors of the second inspection station I2 are distinct straight lines with a pairwise inter-direction angle β and are adapted to capture light from an associated illumination zone S21, S22, and S23. In other words, each image sensor C21, C22, and C23 of the second inspection station I2 is adapted to capture light from an associated illumination zone S21, S22, and S23, respectively. Thus, each image sensor C21, C22, and C23, and each associated illumination zone S21, S22, and S23, respectively, are pairwise adapted during image acquisition along the observation directions D21, D22, and D23.

[0076] According to one embodiment, the at least three image sensors C11, C12, C13 of the first inspection station I1 and the at least three image sensors C21, C22, C23 of the second inspection station I2 have at least six observation directions D11, D12, D13, D21, D22, D23, spaced at least 10° apart in pairs. It should be understood that at both inspection stations, the observation directions of the image sensors are all different in angle relative to the trajectory F of direction X. It is thus possible to obtain, for each container, at least six images from six different observation directions, which is particularly advantageous for measuring the diameters and ovality of a section of the container. According to an embodiment illustrated in the figure 7A , the six observation directions D11, D12, D13, D21, D22, D23 have the following observation angle values ​​δ: 35°, 95°, 145°, 225°, 265°, 315°.

[0077] According to another embodiment, the at least three image sensors C11, C12, C13 of the first inspection station I1 have observation directions separated from each other in pairs by at least 30° angle β and preferably by at least 40° angle β, while the at least three image sensors C21, C22, C23 of the second inspection station I2 have observation directions separated from each other in pairs by at least 30° angle β and preferably by at least 40° angle β. Typically, in the example illustrated in the figure 6A The observation directions D11, D12, D13, D21, D22, D23 have the following values: 40°, 90°, 140°, 220°, 270°, 320°. Thus, in each inspection station, the image sensors have neighboring observation directions separated from each other in pairs by an angle β of 50°.

[0078] Image sensors C11, C12, C13 of the first inspection station I1 and image sensors C21, C22, C23 of the second inspection station I2 are controlled by the control system 10 to acquire images of the containers 1 as they move in translation in front of the inspection stations. To this end, the control system 10 is configured so that, when a moving container 1 is successively substantially centered on an observation direction D11, D12, D13, D21, D22, D23 of each of the image sensors C11, C12, C13, C21, C22, C23, each of said image sensors acquires, by each of said image sensors, at least one image of the container illuminated by the associated lighting zone S11, S12, S13, S21, S22, S23, which is successively activated during the acquisition and presents at least the first lighting configuration.

[0079] According to a feature of the invention, the elementary light sources of the lighting zones S11, S12, S13, S21, S22, S23 are controlled by the control system 10 such that: the at least three lighting zones of each inspection station associated with the image sensors have identical angular widths; the at least three lighting zones S11, S12, S13; S21, S22, S23 of each inspection station I1, I2 associated with the image sensors extend with an angular width L11, L12, L13; L21, L22, L23 symmetric with respect to the corresponding observation direction D11, D12, D13, D21, D22, D23; and at least two angularly adjacent lighting zones S11-S12; S12-S13; S21-S22; S22-S23 of each inspection station have a common lighting part S112 S113 S212 S213 considering that the two said lighting zones are not illuminated simultaneously.

[0080] It is clear from the preceding description that the device I according to the invention enables the implementation of a method for in-line inspection of empty glass containers 1, in order to ensure quality control of these containers. Such a method aims to provide a first inspection station I1 as described above and, advantageously, a second inspection station I2 as described above. The containers 1 are conveyed by the transport system II, passing successively in front of each of the image sensors of the two inspection stations. Thus, the central axis A of each container 1 intersects successively the observation directions of each image sensor.

[0081] As this is more precisely apparent from the figure 3A When a container 1 arrives in a position where it is substantially centered on the observation direction D11 of the first image sensor C11 and positioned along the trajectory, the control device 10 controls, on the one hand, the elementary light sources of the illumination zone S11 associated with the first image sensor C11 to be switched on according to at least a first lighting configuration, and on the other hand, the first image sensor C11 so as to acquire by this first image sensor C11, at least one image of the container illuminated by the associated lighting zone S11. In this case, the useful field of observation contains the container or at least a portion of the container to be inspected.According to the invention, the elementary light sources of the illumination zone S11 are controlled such that the illumination zone S11 has an angular width L11 identical to the other angular widths of the illumination zones of the inspection stations that will be activated to illuminate the container passing in front of the other image sensors. Thus, each container 1 is illuminated identically for all the images taken by the image sensors of the inspection stations.

[0082] According to the invention, the elementary light sources of the illumination zone S11 are also controlled such that the illumination zone S11 associated with the first image sensor C11 extends with an angular width L11 symmetrical with respect to the observation direction D11 of this first image sensor C11. In other words, as shown in the figure 3A The angular width L11 is divided by the observation direction into two equal angular sectors. This allows for the same shadow width on the right and left edges of the container images appearing in the captured images. The ratio between the angular width L11 and the apparent diameter of the bottle must be determined according to the containers being inspected, the type of inspection, etc. Furthermore, the useful field of observation may or may not include the edge of the illuminated area.

[0083] According to the invention, the elementary light sources controlled to produce the illumination zone S11 are also controlled to produce the angularly adjacent illumination zone, namely the illumination zone S12, such that the illumination zone S12 has a common illumination area S112 with the illumination zone S11, considering that the two said illumination zones S11 and S12 are not illuminated simultaneously. In other words, the elementary light sources of this common illumination area S112, which are activated during image acquisition by the first image sensor C11, will also be activated during image acquisition by the second image sensor C12. The overlap between the adjacent illumination zones saves space while ensuring the same lighting conditions during image acquisition.Typically, the angular width of the common lighting part S112 is, for example, between 8° and 24°.

[0084] When container 1 arrives in a position where it is substantially centered on the observation direction D12, of the second image sensor C12 positioned along the trajectory ( figure 3B The control device 10, on the one hand, activates the elementary light sources of the lighting zone S12 associated with the second image sensor C12 according to at least the first lighting configuration, and on the other hand, controls the second image sensor C12 so as to acquire, by this second image sensor C12, at least one image of the container illuminated by the associated lighting zone S12. According to the invention, the elementary light sources of the lighting zone S12 are controlled so that the lighting zone S12 has an angular width L12 identical to the angular width of the lighting zone S11 associated with the first image sensor C11.

[0085] According to the invention, the elementary light sources of the illumination zone S12 are also controlled such that the illumination zone S12 associated with the second image sensor C12 extends with an angular width L12 symmetrical with respect to the observation direction D12 of this second image sensor C12. Thus, as shown in the figure 3B , the angular width L11 is divided by the observation direction into two equal angular sectors.

[0086] According to the invention, the elementary light sources of the lighting zone S12 are controlled in such a way that this lighting zone S12 and the angularly adjacent lighting zone, namely lighting zone S11, share a common lighting area S112, as explained previously. Thus, the elementary light sources of this common lighting area S112 are switched on simultaneously with the other elementary sources forming the remainder of the lighting zone S12.

[0087] When container 1 arrives in a position where it is substantially centered on the observation direction D13 of the third image sensor C13 positioned along the trajectory ( figure 3C The control device 10, on the one hand, activates the elementary light sources of the lighting zone S13 associated with the third image sensor C13 according to at least the first lighting configuration, and on the other hand, controls the third image sensor C13 so as to acquire, by this third image sensor C13, at least one image of the container illuminated by the associated lighting zone S13. According to the invention, the elementary light sources of the lighting zone S13 are controlled so that the lighting zone S13 has an angular width L13 identical to the angular width of the other lighting zones S11, S12 associated with the other image sensors.

[0088] According to the invention, the elementary light sources of the illumination zone S13 are also controlled such that the illumination zone S13 associated with the third image sensor C13 extends with an angular width L13 symmetrical with respect to the observation direction D13 of this third image sensor C13. Thus, as shown in the figure 3C , the angular width L13 is divided by the observation direction into two equal angular sectors.

[0089] According to the invention, the elementary light sources of the lighting zone S13 are also controlled in such a way that this lighting zone S13 and the angularly adjacent lighting zone, namely the lighting zone S12, have a common lighting part S113 as explained previously.

[0090] The overlap between adjacent illumination zones Sij and Sij+1 allows, if necessary, the installation of an image sensor Cij' (where i is the inspection station number and j is the image sensor number) with an observation direction Dij' located between the observation directions Dij and Dij+1 of an image sensor Cij and the neighboring image sensor Cij+1. This allows the elementary light sources to be controlled to produce an illumination zone Sij' that overlaps the illumination zones Sij and Sij+1. Due to the continuity of the emitting surfaces S1 and S2, the illumination zone Sij' can exhibit at least a uniform configuration and an angular width equal to that of the illumination zones Sij and Sij+1. This advantage is even more apparent when considering the unique diffuser, which reinforces the spatial continuity and uniformity of the illumination of the emitting surfaces S1 and S2.

[0091] The inspection method has been described in detail for a container 1 moved into the first inspection station I1. Of course, the inspection method according to the invention is implemented in the same way when the container 1 moves into the second inspection station I2. Thus, the elementary light sources of the lighting zones S21, S22, S23 are controlled so that the at least three lighting zones S21, S22, S23 associated with the image sensors C21, C22, C23 have identical angular widths and extend with a symmetrical angular width with respect to the corresponding observation direction D21, D22, D23 of each image sensor, considering that at least two angularly close lighting zones S21-S22; S22-S23 have a common lighting area S212, S213 with the condition that the two said common lighting areas S212, S213 are not lit simultaneously.The inspection procedure for this second inspection station is not described in more detail, as it follows directly from the preceding description. It follows that the images of each container 1 are taken under identical lighting conditions, regardless of the viewing directions of the image sensors. Indeed, the containers receive light from the same angles.

[0092] According to an advantageous feature, the method aims to perform an analysis of the images taken for each container, using images obtained from different sensors Cij with the associated illumination zones Sij for each acquisition and from different observation directions Dij that exhibit the same configuration of illumination zones. Such an analysis of the images taken for each container makes it possible to deduce information about the dimensions of the containers and / or optical singularities. In the example illustrated in the drawings, the method provides, for each container, six images taken with image sensors that have the same configuration of illumination zones.

[0093] Of course, the process can be implemented in such a way as to increase the number of images captured for each of the containers passing through inspection stations I1 and I2. One solution is to add one or more image sensors to the first inspection station I1 and / or the second inspection station I2, thereby increasing the number of observation directions, as illustrated in particular by the example embodiment shown in the figure 8A featuring seven image sensors.

[0094] Another solution, without changing the light sources L1 and L2, involves increasing the number of observation directions for the image sensors by simply adapting the control of the first and / or second light source so that each provides multiple illumination zones with at least one initial lighting configuration. The control system 10 thus drives the elementary light sources of the first and / or second light source to create multiple illumination zones with at least one initial lighting configuration. In addition to increasing the number of observation directions for the image sensors, the method can also modify the angle values ​​of these observation directions relative to the direction of movement. This modification of the angle values ​​of the observation directions is achievable by adapting only the control.Of course, this modification of the angle values ​​of the observation directions can be carried out without changing the number of directions of the image sensors. Alternatively, it is possible to move the image sensors or change the direction of their optical axes by modifying only the control parameters for the illumination.

[0095] To increase the number of images taken, it may be provided that at least one image sensor acquires at least two images of each container from at least two different viewing directions following the movement of the container within the total viewing field of the image sensor.

[0096] In the various implementation variants described above for increasing the number of shots, the lighting zones have a single, primary configuration. Of course, the lighting zones can have several different lighting configurations depending on the type of control or observation desired, as already explained.

[0097] According to one embodiment, the process provides in each inspection station I1, I2 for each container inspected in transit: to make available for the emitting surface S1, S2 of each light source L1, L2, at least three lighting zones S11, S12, S13- S21, S22, S23 having at least the first identical lighting configuration, a second identical lighting configuration and a third identical lighting configuration; and when the container 1 is substantially centered on an observation direction D11, D12, D13, D21, D22, D23 of an image sensor, to acquire by each of said image sensors, successively at least one image of the container illuminated by the associated lighting zone, having the first lighting configuration, at least one image of the container illuminated by the associated lighting zone having the second lighting configuration and at least one image of the container illuminated by the associated lighting zone, having the third lighting configuration.

[0098] Thus, for one such embodiment, it is possible to obtain, for each container 1, at least six images from at least six different viewing directions, allowing inspection of the entire periphery of each container for each of the three different lighting configurations in order to perform several types of inspection, i.e., at least 18 images in total. The object of the invention thus makes it possible to check various characteristics of the containers during a single pass through the inspection stations, with the possibility of highlighting features and / or defects, depending on the lighting configuration used.

[0099] According to an advantageous implementation example, the at least three lighting zones S11, S12, S13- S21, S22, S23 exhibit: as first identical lighting configuration Fb, a uniform light illuminance zone inside a closed contour; as second identical lighting configuration Fa, a uniform light illuminance zone inside a closed contour with an angular width 40% less than the angular width of the first identical configuration; as third identical lighting configuration Fc, a variation in intensity, color or polarization between superimposed zones parallel to the conveying plane Pc.

[0100] In this example, the at least three illumination zones S11, S12, S13-S21, S22, S23 are each associated respectively with image sensors C11, C12, C13-C21, C22, C23 and centered on their observation directions D11, D12, D13, D21, D22, D23, and each successively exhibit at least a first, a second, and a third illumination configuration. It is assumed that the observation direction does not change between successive image acquisitions of a container by the same image sensor. This is an acceptable simplification of operation because the actual displacement between these acquisitions is small, thus achieving the condition of centering the illuminated zone on the observation direction of the associated image sensor, which is assumed to be fixed.

[0101] According to one embodiment of the invention, when the image sensor C12 acquires three images of the same container moving through the inspection station I1, with an associated illumination zone S12 centered on the observation direction D12 and exhibiting three illumination configurations Fa, Fb, and Fc modified at each acquisition, the observation direction D12 changes according to the movement of the container, as seen between the figures 9A, 9B then 9C. It is then advantageous for the illumination zone S12 to move to remain centered on the varying observation direction. In other words, it could be considered that each image sensor C12 acquires three images according to three different observation directions D12 by cooperating with three illumination zones S12 associated with the three observation directions.

[0102] Because the displacement between two acquisitions is small, the successively activated illumination zones for a container, associated with the acquisitions by a given image sensor, overlap but are offset. This offset is significant when the calculated displacement of the intersection of the observation direction with the emitting surface between two successive acquisitions is greater than the smallest possible offset of the illumination zone, which corresponds to the width of a single light source. Thus, for containers moving at a speed of 1 m / s with acquisitions spaced 1 ms apart, the displacement between two acquisitions by the same image sensor is on the order of a millimeter.Therefore, if the width of the individual light sources is significantly greater than one millimeter, it is not advantageous to include this offset, and the area remains fixed. In other words, successive configurations associated with the same image sensor overlap without any offset, as they are all centered on the observation direction of that image sensor. That being said, the offset and overlap between lighting areas associated with different image sensors remains necessary to reduce the footprint of inspection stations.

[0103] Thus, the procedure provides for each inspection station I1 - I2 for each container inspected in transit: to make available for the emitting surface S1 - S2 of each light source L1, L2, at least nine lighting zones having at least the first identical lighting configuration, a second identical lighting configuration and a third lighting configuration, and when the container 1 is substantially centered on an observation direction of an image sensor C11, C12, C13, C21, C22, C23, to acquire by each of said image sensors, successively at least one image of the container illuminated by an associated lighting zone, having the first lighting configuration, at least one image of the container illuminated by an associated lighting zone having the second lighting configuration and at least one image of the container illuminated by an associated lighting zone, having the third lighting configuration.

[0104] According to an advantageous feature of the invention, the working distances W of the at least three image sensors C11, C12, C13 of the first station I1 are substantially identical for the same lighting configuration. By substantially identical, it is understood that their relative differences are less than 10%.

[0105] According to an advantageous feature of the invention, the at least three image sensors C21, C22, C23 of the second inspection station have substantially identical working distances W.

[0106] In other words, according to a preferred variant, the invention consists of providing in an inspection station I1, I2 at least three image sensors C11, C12, C13 - C21, C22, C23, all having an identical working distance W at the time of image acquisition under the same lighting configuration.

[0107] According to another embodiment of the invention, the at least three image sensors C21, C22, C23 of the second inspection station have working distances W identical to the working distances of the at least three image sensors C11, C12, C13 of the first inspection station. In other words, all the image sensors C11, C12, C13 and C21, C22, C23 of the two inspection stations have substantially identical working distances W.

[0108] In other words, according to another preferred variant, the invention consists of providing in a first inspection station I1 at least three image sensors C11, C12, C13 and in a second inspection station I2 at least three image sensors C21, C22, C23, all having a working distance W substantially identical at the time of image acquisition under the same lighting configuration.

[0109] Preferably, so that the working distances W are substantially identical at the time of image acquisition under the same lighting configuration, the device is designed so that the distances taken along the optical axis between the optical centers O of sensors C11, C12, C13 and C21, C22, C23 and the trajectory F of the containers are identical.

[0110] It is clear from the preceding description that the object of the invention has the advantage of presenting one or more light sources whose emitting surface is homogeneous and continuous, allowing a wide choice of observation directions for image sensors, from any angles.

[0111] The method according to the invention improves the detection of the appearance of containers by balancing the shadows on each side of the container, thereby improving detection performance as shown in the figure 5A compared to the shots of the figure 5B carried out with a plane emitting source parallel to the trajectory.

[0112] The method according to the invention improves the detection of container appearance by revealing, with the same contrast, a defect such as broth when positioned in the center of the container, both in central views with the observation direction placed approximately at the plane of symmetry of the light sources and in lateral views with the observation directions positioned on either side of the plane of symmetry of the light sources. This is due, on the one hand, to the curvature of the emitting surface S1, S2 of the light sources, which maintains a virtually constant distance between the emitting surface and the container, and on the other hand, to the symmetry of the illuminated area with respect to the observation direction. This results in the same contrast for a defect regardless of the image sensors observing it.

[0113] Since defect detection remains identical regardless of the container's orientation as it passes through the inspection stations, the method according to the invention allows for repeatable inspections by acquiring identical images regardless of the container's orientation and the observation direction. This is achieved by ensuring that at least six images for each configuration (appearance inspection, dimensional inspection, stress inspection, or lighting pattern inspection) are identical. The method makes it possible to obtain the same image rendering regardless of the image sensor's viewing angle around the container.

[0114] This repeatability is increased in the variant of the invention in which the working distances W of the image sensors are substantially identical. Indeed, since this working distance W is identical, the angles γ of the rays emanating from the container with respect to the observation direction are the same for the different images ( figure 11 ). So the apparent contrast of the defects, especially those refracting light, as well as the shadows at the edges of the containers, are the same because the optical paths from the source S1 S2 to the image sensors Cij are similar for the different images acquired by the different image sensors, for a given lighting configuration.

[0115] Furthermore, the method according to the invention offers the advantage of being able to measure as many different diameters as there are image sensors in a compact form factor, provided the image sensors have different viewing directions. Thus, the method allows for the analysis of six images taken by at least six image sensors at a given height, within the images scanned from the bottom of the container upwards, to determine the distance between two opposite edges of the container. This distance then allows for the calculation of the container's diameter in millimeters at that height.It is thus possible to determine information on the dimensions of the containers and in particular the dimensional conformity of the container from measurements of at least six different diameters according to six different directions of observation compared to diameter tolerance thresholds or non-circularity thresholds for at least a given height of the container.

[0116] According to an alternative embodiment illustrated in the figure 7A The first inspection station I1 comprises three image sensors C11, C12, and C13 with observation directions and observation angles δ measured counterclockwise relative to the direction of travel of 35°, 95°, and 145°, respectively. The second inspection station I2 comprises three image sensors with observation directions and observation angles δ measured counterclockwise of 225°, 265°, and 315°, respectively, relative to the direction of travel. It is observed that the observation directions are straight lines, each with an angle of at least 10° between pairs. On the Figure 7B The diameters seen by the six respective image sensors are shown for a cross-section of a supposedly cylindrical container, and we can therefore observe that six different diameters are measured (5°, 55°, 135°, 175°, 225°, 305°), which guarantees an improvement in the measurement of ovalizations or "non-rounds," that is, containers whose normally round circumference is not round, often exhibiting a local flat spot. figures 6A et 6B In contrast, they present a machine such that the two inspection stations I1 and I2 each have, as per the prior art, image sensors arranged symmetrically with respect to the conveyor, thus measuring only three different diameters. The average error in the ovality measurement is greater in the illustrated embodiment than figures 6A, 6B compared to the example illustrated in figures 7A et 7B This reasoning considers telecentric aiming, but it applies motus mutandis in the common case of image sensors with non-telecentric optics but long focal lengths.

[0117] According to the invention, thanks to the curved emitting surface, it is possible to arrange any number of image sensors with any observation direction, except along the axis of the conveyor. Thus, according to the figure 8A Seven image sensors are arranged with their observation directions distributed angularly so that, as illustrated in the figure 8B Seven different diameters are measured. Here again, the accuracy of measuring ovalities and non-round containers is improved compared to a symmetrical arrangement of an even number of image sensors as proposed by prior art.

Claims

1. A method for inspecting containers (1) moved in a conveying plane (Pc) with a rectilinear path, the method comprising in a first inspection station (I1): - providing a first light source (L1) illuminating the containers along a first side of the path, comprising an emitting surface (S1) having a plane of symmetry (P) perpendicular to the path and extending, on the one hand, in height in a vertical direction (Z) normal to the conveying plane (Pc) and, on the other hand, over a total angular width, following a concave curve, the emitting surface (S1) being composed of a plurality of elementary light sources controlled so as to define at least three illumination zones (S11, S12, S13) having at least one first identical illumination configuration; - providing at least three image sensors (C11, C12, C13) with total observation fields and disposed with optical axes in different directions along a second side of the path opposite the first side, in order to each have, during an image acquisition of a container present in its total observation field, an observation direction (D11, D12, D13) passing through the optical centre and the central axis of the container, the observation directions for the at least three image sensors being different straight lines and adjusted to recover the light coming from an associated illumination zone; - and when a container (1) in movement is successively located substantially centred on an observation direction (D11, D12, D13) of each of the image sensors, in order for each of said image sensors to acquire at least one image of the container illuminated by the associated illumination zone controlled to be switched on successively during the acquisition, having at least the first illumination configuration, the elementary light sources of the illumination zones (S11, S12, S13) being controlled in such a way that: * the at least three illumination zones (S11, S12, S13) associated with the image sensors have identical angular widths (L11, L12, L13); * the at least three illumination zones (S11, S12, S13) associated with the image sensors extend with a symmetrical angular width (L11, L12, L13) relative to the corresponding observation direction (D11, D12, D13); * and at least two angularly neighbouring illumination zones (S11-S12, S12-S13), have a common illumination portion (S112; S113) considering that said two illumination zones are not illuminated simultaneously.

2. The method according to the preceding claim, wherein in a second inspection station (I2) located downstream of the first inspection station (I1) in the direction of movement of the containers, the method comprises: - providing a second light source (L2) illuminating the containers along the second side of the path, comprising an emitting surface (S1) having a plane of symmetry (P) perpendicular to the path and extending, on the one hand, in height in a vertical direction (Z) normal to the conveying plane (Pc) and, on the other hand, over a total angular width, following a concave curve, the emitting surface (S2) being composed of a plurality of elementary light sources controlled so as to define at least three illumination zones (S21, S22, S23) having at least one first identical illumination configuration; - providing at least three image sensors (S21, S22, S23) with total observation fields and disposed with optical axes in different directions along the first side of the path, in order to each have, during an image acquisition of a container present in its total observation field, an observation direction (D21, D22, D23) passing through the optical centre and the central axis of the container, the observation directions (D11, D12, D13) for the at least three image sensors being different straight lines and adjusted to recover the light coming from an associated illumination zone; - and when a container (1) in movement is successively located substantially centred on an observation direction (D11, D12, D13) of each of the image sensors, in order for each of said image sensors to acquire at least one image of the container illuminated by the associated illumination zone controlled to be switched on successively during the acquisition, having at least the first illumination configuration, the elementary light sources of the illumination zones (S21, S22, S23) being controlled in such a way that: * the at least three illumination zones (S21, S22, S23) associated with the image sensors (C21, C22, C23) have identical angular widths (L21, L22, L23); * the at least three illumination zones (S21, S22, S23) associated with the image sensors extend with a symmetrical angular width (L21, L22, L23) relative to the corresponding observation direction (D21, D22, D23); * and at least two angularly neighbouring illumination zones (S21-S22; S22-S23), have a common illumination portion (S213, S212) considering that said two illumination zones are not illuminated simultaneously.

3. The method according to one of the preceding claims, wherein the first light source (L1) is provided with an emitting surface (S1) produced by a portion of a generalised cylinder created by a generatrix produced by a segment of vertical straight line and a concave directrix curve in the conveying plane, the concavity of which is turned towards the containers.

4. The method according to one of the preceding claims, wherein the first light source (L1) is provided with an emitting surface (S1) with a total angular width between 10° and 175° and / or with an emitting surface (S1) having, in the conveying plane, a width between 500 mm and 700 mm and a depth between 100 mm and 350 mm.

5. The method according to one of the preceding claims, wherein in the first inspection station (I1): - at least three illumination zones (S11, S12, S13) are provided for the emitting surface (S1) of the first light source (L1), having at least the first identical illumination configuration, a second identical illumination configuration and a third identical illumination configuration; - and when a container (1) is substantially centred on an observation direction (D11, D12, D13) of an image sensor, in order for each of said image sensors to successively acquire at least one image of the container illuminated by the associated illumination zone, having the first illumination configuration, at least one image of the container illuminated by the associated illumination zone, having the second illumination configuration and at least one image of the container illuminated by the associated illumination zone, having the third illumination configuration.

6. The method according to one of the preceding claims, wherein in the first inspection station at least three illumination zones (S11, S12, S13) are provided for the emitting surface (S1) of the first light source (L1), having: - as a first identical illumination configuration, an extended configuration with suitable homogeneous pattern; - as a second identical illumination configuration, a restricted homogeneous configuration; - as a third identical illumination configuration, a structured configuration.

7. The method according to any one of claims 2 to 6, wherein at least three image sensors (C11, C12, C13) are provided in the first inspection station (I1) and at least three image sensors (C21, C22, C23) are provided in the second inspection station (I2), said at least six image sensors having at least six observation directions (D11, D12, D13, D21, D22, D23) spaced apart in pairs by at least 10°.

8. The method according to any one of claims 2 to 7, wherein, the number and / or angular value of the observation directions (D11, D12, D13, D21, D22, D23) of the image sensors relative to the direction of movement are modified by only adjusting the control of the first light source (L1), and / or of the second light source (L2), in order to have at least three illumination zones having at least one first illumination configuration.

9. The method according to any one of claims 2 to 8, wherein at least one image sensor (C11, C12, C13, C21, C22, C23) acquires at least two images of each container in at least two different observation directions, following the movement of the container in the total observation field of the image sensor.

10. The method according to one of the preceding claims, wherein an analysis of the images taken by the image sensors (C11, C12, C13, C21, C22, C23) with the same configuration of the illumination zones is carried out in order to derive information concerning defects and / or dimensions of the containers.

11. The method according to claim 7, wherein: - the analysis of the six images taken by the at least six image sensors (C11, C12, C13, C21, C22, C23) is carried out at at least one given height in the images scanned from the bottom of the container to the top, in order to determine the distance between two opposite edges of the container, in order to derive a measurement of the diameter of the container at said height, - the dimensional conformity of the container is determined on the basis of the measurements of at least six different diameters in six different directions compared with diameter tolerance thresholds or non-circularity thresholds for at least one given height of the container.

12. The method according to one of the preceding claims consisting in providing, in one inspection station (I1, I2), at least three image sensors (C11, C12, C13, C21, C22, C23), having a substantially identical working distance (W) at the time of acquisition of the images with a same illumination configuration.

13. A device for inspecting containers moved in a conveying plane (Pc) with a rectilinear path, this inspection device comprising: * a first inspection station (I1) comprising: - a first light source (L1) along a first side of the path, comprising an emitting surface (S1) having a plane of symmetry (P1) perpendicular to the path and extending, on the one hand, in height in a vertical direction normal to the conveying plane (Pc) and, on the other hand, over a total angular width following a concave curve, the emitting surface (S1) being composed of a plurality of elementary light sources controlled so as to define at least three illumination zones (S11, S12, S13) having at least one first identical illumination configuration; - at least three image sensors (C11, C12, C13) with total observation fields and disposed with optical axes in different directions along a second side of the path opposite the first side, in order to each have, during an image acquisition of a container present in its total observation field, an observation direction (D11, D12, D13) passing through the optical centre and the central axis of the container, the observation directions for the image sensors being different and adjusted to recover the light coming from an associated illumination zone; * a second inspection station (I2) located downstream of the first inspection station in the direction of movement of the containers, this second inspection station comprising: - a second light source (L2) along the second side of the path, comprising an emitting surface (S2) having a plane of symmetry (P2) perpendicular to the path and extending, on the one hand, in height in a vertical direction normal to the conveying plane (Pc) and, on the other hand, over a total angular width following a concave curve, the emitting surface (S2) being composed of a plurality of elementary light sources controlled so as to define at least three illumination zones (S21, S22, S23) having at least one first identical illumination configuration; - at least three image sensors (C21, C22, C23) with total observation fields and disposed with optical axes in different directions along the first side of the path, in order to each have, during an image acquisition of a container present in its total observation field, an observation direction (D21, D22, D23) passing through the optical centre and the central axis of the container, the observation directions for the image sensors being adjusted to recover the light coming from an associated illumination zone, the observation directions for the image sensors of the second inspection station being mutually different straight lines and different from the observation directions of the image sensors of the first inspection station; * and a control system (10) of the light sources (L1, L2) and the image sensors (C11, C12, C13, C21, C22, C23) configured so that when a container in movement is successively located substantially centred on an observation direction (D11, D12, D13, D21, D22, D23) of each of the image sensors, in order for each of said image sensors to acquire at least one image of the container illuminated by the associated illumination zone controlled to be switched on successively during the acquisition, having at least the first illumination configuration, the elementary light sources (S11, S12, S13, S21, S22, S23) of the illumination zones being controlled in such a way that: - the at least three illumination zones (S11, S12, S13, S21, S22, S23) of each inspection station associated with the image sensors have identical angular widths; - the at least three illumination zones (S11, S12, S13, S21, S22, S23) of each inspection station associated with the image sensors extend with a symmetric angular width relative to the corresponding observation direction (D11, D12, D13, D21, D22, D23); - and at least two angularly neighbouring illumination zones of each inspection station, have a common illumination portion considering that said two illumination zones are not simultaneously illuminated.

14. The inspection device according to the preceding claim, wherein the at least three image sensors (C11, C12, C13, C21, C22, C23) of each inspection station (I1, I2) have observation directions (D11, D12, D13, D21, D22, D23) which are straight lines spaced apart in pairs by an angle of at least 30° and preferably at least 40°.

15. The inspection device according to one claims 13 to 14, wherein at least three image sensors (C11, C12, C13) in a first inspection station (I1) and at least three image sensors (C21, C22, C23) in a second inspection station (I2) each have a substantially identical working distance taken along the optical axis between their optical centre and the path (F) of the containers.