法国专利FR3063596A1 SYSTEM FOR ACQUIRING IMAGES

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专利摘要:
An image acquisition system (10) includes: - a source (22) of radiation (44); an image sensor (14) comprising a matrix of photodetectors adapted to detect said radiation and comprising a face (15); and - an angular filter (16), covering the sensor, and adapted to block the radii of said radiation whose incidence relative to a direction orthogonal to the face is greater than a threshold and to let at least some radii of said radiation of which the incidence with respect to a direction orthogonal to the face is less than the threshold.
公开号:FR3063596A1
申请号:FR1757669
申请日:2017-08-11
公开日:2018-09-07
发明作者:Wilfrid Schwartz；Agathe Puszka；Quentin CHABLE；Benjamin BOUTHINON
申请人:Isorg SA；
IPC主号:

专利说明:

(54) IMAGE ACQUISITION SYSTEM.
The invention relates to an image acquisition system (10) comprising:
- a source (22) of radiation (44);
- an image sensor (14) comprising a matrix of photodetectors adapted to detect said radiation and comprising a face (15); and
- An angular filter (16), covering the sensor, and adapted to block the rays of said radiation whose incidence relative to a direction orthogonal to the face is greater than a threshold and to allow at least certain rays of said radiation to pass through. incidence relative to a direction orthogonal to the face is less than the threshold.
B16100 - Angular filtering
IMAGE ACQUISITION SYSTEM
Field
The present application relates to an image acquisition system.
Presentation of the prior art
An image acquisition system generally comprises an image sensor and an optical system, interposed between the sensitive part of the image sensor and the object to be imaged and which makes it possible to form a clear image of the object to be imaged on the sensitive part of the image sensor.
However, in certain cases, it is not possible to have such an optical system between the sensitive part of the image sensor and the object to be imaged. This is particularly the case when the image sensor occupies a large surface, greater than the square centimeter and the distance between the object to be imaged and the sensitive part of the image sensor is less than the centimeter.
It would then be necessary to place the object to be imaged as close as possible to the image sensor so that the image which forms on the sensitive part of the image sensor is sufficiently clear. However, there may be a distance between the object and the image sensor so that the sharpness of the image that forms on the sensitive part of the image sensor may not be sufficient
B16100 - Angular filtering for certain applications, for example for capturing fingerprints.
summary
An object of an embodiment is to increase the sharpness of the image acquired by the image sensor of an image acquisition system in the absence of an optical system forming a sharp image of the object. to be imaged on the sensitive part of the image sensor.
Another object of an embodiment is that the area of the sensitive part of the image sensor is greater than the square centimeter.
Another object of an embodiment is that the distance between the object to be imaged and the sensitive part of the image sensor is less than a centimeter.
Another object of an embodiment is that the distance between the object to be imaged and the sensitive part of the image sensor is greater than fifty micrometers.
Thus, one embodiment provides an image acquisition system comprising:
- a source of radiation;
- an image sensor comprising a matrix of photodetectors adapted to detect said radiation and comprising a face; and
- An angular filter, covering the image sensor, and adapted to block the rays of said radiation whose incidence relative to a direction orthogonal to the face is greater than a threshold and to let through rays of said radiation whose incidence relative to a direction orthogonal to the face is less than the threshold.
According to one embodiment, the system further comprises a coating, at least partially transparent to said radiation and covering the image sensor, the angular filter being interposed between the coating and the image sensor.
According to one embodiment, the source is adapted to emit said radiation in the coating from the periphery
B16100 - Angular filtering of the coating, the coating acting as a waveguide for said radiation.
According to one embodiment, the radiation is in the visible range and / or in the infrared range.
According to one embodiment, the angular filter comprises a matrix of holes delimited by walls opaque to said radiation or made of a polarizing material, the holes being filled with air or a material at least partially transparent to said radiation.
According to one embodiment, for each hole, the ratio between the height of the hole, measured perpendicular to the face, and the width of the hole, measured parallel to the face, varies from 1 to 10.
According to one embodiment, the holes are arranged in rows and columns, the pitch between adjacent holes of the same row or of the same column varying from 10 μm to 30 μm.
According to one embodiment, the height of each hole, measured in a direction orthogonal to the face, varies from 1 μm to 1 mm.
According to one embodiment, the width of each hole, measured parallel to the face, varies from 5 μm to 30 μm.
According to one embodiment, the walls are entirely made of a material opaque to said radiation.
According to one embodiment, each wall comprises a core made of a material transparent to said radiation covered with a layer opaque to said radiation.
According to one embodiment, the system further comprises lenses covering the holes.
According to one embodiment, the system comprises, for each hole, a lens covering the hole and in contact with the walls.
According to one embodiment, the photodetectors comprise organic photodiodes.
One embodiment provides a display system comprising the image acquisition system as defined
B16100 - Previously angular filtering and further comprising a display screen, the angular filter being interposed between the display screen and the image sensor.
According to one embodiment, the display screen comprises a matrix of electroluminescent components and the photodetectors are offset with respect to the electroluminescent components in a direction perpendicular to the face.
According to one embodiment, the light-emitting components are separated from each other by intermediate zones and the photodetectors are situated in the extension of said intermediate zones in a direction perpendicular to said face.
According to one embodiment, the display screen comprises a matrix of electroluminescent components, the electroluminescent components are at least partly transparent to radiation and the electroluminescent components are located at least partly opposite the photodetectors in a direction perpendicular to said direction. face.
According to one embodiment, the light-emitting components comprise organic light-emitting diodes.
One embodiment also provides for the use of the display system as defined above for the detection of at least one fingerprint of a user.
One embodiment also provides a method of manufacturing an image acquisition system, comprising the following steps:
- provide a source of radiation;
- forming an image sensor comprising a matrix of photodetectors adapted to detect said radiation and comprising a face; and
- forming an angular filter, covering the image sensor, and adapted to block the rays of said radiation whose incidence relative to a direction orthogonal to the face is greater than a threshold and to allow rays of said radiation to pass
B16100 - Radiation angular filtering whose incidence relative to a direction orthogonal to the face is less than the threshold.
According to one embodiment, the angular filter comprises a matrix of holes delimited by walls opaque to said radiation, the formation of the angular filter comprising the following steps:
forming a layer of a photosensitive resin; and forming the walls by etching the layer by photolithography.
According to one embodiment, the photosensitive resin is a black or colored resin.
According to one embodiment, the angular filter comprises a matrix of holes delimited by walls opaque to said radiation, the formation of the angular filter comprising the following steps:
formation of a transparent resin mold, by photolithography steps, of shape complementary to the desired shape of the walls;
filling the mold with the material making up the walls; and removing the structure obtained from the mold.
According to one embodiment, the angular filter comprises a matrix of holes delimited by walls opaque to said radiation, each wall comprising a core made of a material transparent to said radiation covered with a layer opaque to said radiation, the formation of the angular filter comprising the steps following:
forming a layer of a photosensitive resin transparent to said radiation;
etch the layer by photolithography according to the desired shape of the walls; and covering the structure obtained with the layer opaque to said radiation.
B16100 - Angular filtering
According to one embodiment, the formation of the angular filter comprises the perforation of holes of micrometric size in a black or colored film.
According to one embodiment, the holes are drilled by means of micrometric size needles.
Brief description of the drawings
These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments made without implied limitation in relation to the attached figures among which:
Figures 1 and 2 are sectional views, partial and schematic, of embodiments of an image acquisition system;
Figure 3 is a sectional view of an embodiment of an image sensor of the image acquisition system of Figure 2;
Figure 4 is a sectional, partial and schematic view of another embodiment of an image acquisition system;
Figures 5 and 6 are sectional views similar to Figure 4 illustrating the operation of the image acquisition system of Figure 4 used as a fingerprint sensor;
Figure 7 is a partial and schematic top view of an embodiment of a display system comprising a display screen and an image sensor;
Figures 8 and 9 are top views, partial and schematic, of two arrangements of the display screen display pixels and the photodetectors of the image sensor of the display system of Figure 7;
Figures 10 and 11 are respectively a sectional view and a top view, partial and schematic, of an embodiment of an angular filter; and
B16100 - Angular filtering Figures 12 to 17 are sectional views, partial and schematic, of other embodiments of an angular filter.
detailed description
For the sake of clarity, the same elements have been designated by the same references in the different figures and, moreover, as is usual in the representation of electronic circuits, the various figures are not drawn to scale. In the following description, when referring to qualifiers of absolute position, such as the terms forward, backward, up, down, left, right, etc., or relative, such as the terms above, below, top , lower, etc., reference is made to the orientation of the figures or to an image acquisition system in a normal position of use. In addition, only the elements useful for understanding this description have been shown and are described. In particular, the use made of the sensors described below has not been detailed. In addition, the structure of an image acquisition system is well known to those skilled in the art and will not be described in detail below. In addition, the signal processing means provided by the image acquisition systems described below are within the reach of those skilled in the art and will not be described. In the following description, unless indicated otherwise, the terms substantially and approximately mean to within 10%. In the case of an angle, unless otherwise stated, the terms substantially and approximately mean to the nearest 10 °.
In the following description, electromagnetic radiation whose wavelength is between 400 nm and 700 nm is called visible light and electromagnetic radiation whose wavelength is between 700 nm and 1 mm is called infrared radiation. . In infrared radiation, a distinction is made in particular near infrared radiation whose wavelength is between 700 nm and 1.4 pm.
B16100 - Angular filtering
Figure 1 is a sectional view, partial and schematic, of an embodiment of an image acquisition system 10 of an object 12, partially shown in Figure 1. The image acquisition system 10 comprises from bottom to top in FIG. 1:
an image sensor 14 having an upper face 15; an angular filter 16; and a light source 22.
The image acquisition system 10 further comprises means, not shown, for processing the signals supplied by the image sensor 14, comprising for example a microprocessor.
Figure 2 is a sectional view, partial and schematic, of another embodiment of an image acquisition system 25 of the object 12. The image acquisition system 25 comprises the assembly elements of the image acquisition system 10 and further comprises a coating 18 having opposite upper and lower faces 20, 21 covering the angular filter 16 on the side opposite to the image sensor 14.
Figure 3 is a sectional view of an embodiment of the image sensor 14. The image sensor 14 comprises a support 24 and a matrix 26 of photon sensors 28, also called photodetectors, arranged between the support 24 and the angular filter 16. The photodetectors 28 can be covered with a transparent protective coating, not shown. The image sensor 14 further comprises conductive tracks and switching elements, in particular transistors, not shown, allowing the selection of the photodetectors 28. The photodetectors 28 can be made of organic materials. The photodetectors 28 may correspond to organic photodiodes (OPD, from the English Organic Photodiode) or to organic photoresistors. The surface of the image sensor 14 facing the angular filter 16 and containing the photodetectors 28 is greater is greater than 1 cm ^, preferably greater than
B16100 - Angular filtering cm ^, more preferably greater than 10 cm ^, in particular greater than 20 cm ^. The face 15 can be substantially flat.
The coating 18 is at least partially transparent to the radiation emitted by the light source 22. The coating 18 can have a thickness of between 1 μm and 10 mm. The upper face 20 and the lower face 21 may be substantially flat.
The angular filter 16 is adapted to filter the incident radiation as a function of the incidence of the radiation relative to the upper face 20 of the angular filter 16, in particular so that each photodetector 28 receives only the rays whose incidence relative to an axis perpendicular to the upper face 20 of the angular filter 16 is less a maximum angle of incidence less than 45 °, preferably less than 30 °, more preferably less than 20 °, even more preferably less than 10 °. The angular filter 16 is adapted to block the rays of the indicative radiation whose incidence relative to an axis perpendicular to the upper face 20 of the angular filter 16 is less is greater than the maximum angle of incidence.
In the embodiment shown in FIG. 1 or 2, the object 12 whose image is acquired by the image sensor 14 is interposed between the light source 22 and the angular filter 16 or the coating 18. The image is obtained by transmission of the radiation emitted by the light source 22 through the object 12. The radiation emitted by the source 22 can be visible radiation and / or infrared radiation. For an application for determining fingerprints, the object 12 corresponds to the finger of a user. Preferably, the finger 12 is in contact with the upper face 20 of the image acquisition system 10 so that the light rays passing through contact zones 30 between the object 12 and the face 20 are strongly transmitted while the light rays passing through non-contact areas 32, also called valleys, are more weakly transmitted. The photodetectors 28 located opposite the contact zones 30
B16100 - Angular filtering collect the scattered light at low incidence while the photodetectors 28 located opposite the non-contact areas 32 collect little light since this is essentially blocked by the angular filter 16.
Figure 4 is a sectional, partial and schematic view of another embodiment of an image acquisition system 40. The image acquisition system 40 comprises all of the elements of the image 'image acquisition 25 shown in Figure 2 with the difference that the light source 22 is replaced by a light source 42 adapted to emit light radiation 44 in the coating 18 which then plays the role of a waveguide. The radiation 44 emitted by the source 42 can be visible radiation and / or infrared radiation. Radiation 44 is injected into coating 18 from the periphery of coating 18. In the embodiment shown in FIG. 4, radiation 44 is injected into coating 18 from a side edge 46 of coating 18. According to another embodiment , the radiation 44 is injected into the coating 18 at the periphery of the coating 18 by the upper face 20 or the lower face 21, preferably by the lower face 21. In the present embodiment, the coating 18 preferably has a thickness between 0.1 mm and 1 mm. The coating 18 can be made of glass, or of a plastic material.
According to one embodiment, the beam 44 emitted by the source 42 and propagating in the coating 18 may not be collimated. According to one embodiment, the beam 44 emitted by the source 42 and propagating in the coating 18 is substantially collimated, the rays of the beam 44 being substantially parallel to the faces 20, 21 of the coating 18. This can make it possible to improve the homogeneity of the image of the contact areas 30 acquired by the image sensor 14.
Figures 5 and 6 illustrate the operation of the image acquisition system 40 as a fingerprint sensor. As shown in FIG. 5, the radiation which propagates in the coating 18 is diffused at the level of the
B16100 - Angular filtering of contact zones 30 between the object 12 and the upper face 20 so that the photodetectors 28 of the image sensor 14 facing the contact zones receive the scattered radiation filtered by the angular filter 16. As is represented in FIG. 6, the radiation which propagates in the coating 18 remains confined in the coating 18 at the level of the valleys 32 so that the photodetectors 28 of the image sensor 14 facing the valleys 32 may or may not receive radiation.
Another example of application of the image acquisition system 10 or 40 relates to the image acquisition of a biological material through a transparent support in which the biological material is placed, for example a biological culture placed in a petri dish.
Figure 7 is a sectional view, partial and schematic, of an embodiment of a display system 50 and Figures 8 and 9 are top views, partial and schematic, of the display system 50 according to two different layouts.
The display system 50 includes all of the elements of the image acquisition system 40 shown in FIG. 4 and further comprises a display screen 52 interposed between the coating 18 and the angular filter 16.
The display screen 52 comprises a matrix of display subpixels 54, shown only in FIGS. 8 and
9. Each display sub-pixel 54 comprises an optoelectronic component 56 adapted to emit electromagnetic radiation, called an electroluminescent component in the following description. Each light-emitting component 56 corresponds for example to a light-emitting diode, in particular to an organic light-emitting diode (OLED, from the English Organic Light-Emitting Diode). The display sub-pixels 54 may further comprise conductive tracks and switching elements, in particular transistors, not shown, allowing the selection of the display sub-pixels.
B16100 - Angular filtering
In FIGS. 8 and 9, each display sub-pixel 54 is shown in square shape and each electroluminescent component 56 corresponds to a stack of layers having a substantially square shape. However, it is clear that the shape of the display sub-pixel 54 and the shape of the electroluminescent component 56 can be different, for example polygonal. In the present embodiment, seen from above, the surface occupied by the electroluminescent component 56 is less than the surface of the display sub-pixel 54 and each display sub-pixel 54 comprises an intermediate zone 58 surrounding at least partly the electroluminescent component 56. In FIGS. 8 and 9, the angular filter 16 is not shown.
The display system 50 further comprises means (not shown) for processing the signals supplied by the image sensor 14, comprising for example a microprocessor, and means (not shown) for controlling the display screen 52.
The matrix of light-emitting components 56 is arranged in a plane parallel to the matrix of photodetectors 28. The matrix of photodetectors 28 and the matrix of light-emitting components 56 are superimposed with the interposition of the angular filter 16.
According to one embodiment, a slight offset may be provided between the positions of the light-emitting components 56 and the photodetectors 28 so that, in top view, the light-emitting components 56 are not in whole or in part opposite the photodetectors 28 , so as not to mask the photodetectors 28. This embodiment is suitable for the case where the light-emitting components 56 are not transparent to the radiation detected by the image sensor 14 and that the intermediate zones 58 surrounding the light-emitting components 56 leave the at least partially pass visible light and / or infrared light with a transmittance greater than 5%. According to one embodiment, the
B16100 - Angular filtering photodetectors 28 are located, in top view, between the electroluminescent components 56 of adjacent pixels.
In the arrangement shown in FIG. 8, each photodetector 28 extends, in top view, along the common edge between two adjacent display sub-pixels 54. In the arrangement shown in Figure 9, each photodetector 28 is located, in top view, at the common corner between four adjacent display sub-pixels 54.
According to one embodiment, the entire display screen 52 can have a low transmittance in the visible range. This may be the case when the display screen 52 is a liquid crystal screen comprising a reflector on the rear face of a backlight unit. This can also be the case for certain types of OLED screens. The radiation 44 emitted by the source 42 can then be in a frequency range outside the visible range for which the display screen 52 is at least partially transparent, for example in infrared.
According to another embodiment, in the case where the electroluminescent components 56 are at least partially transparent to the radiation picked up by the photodetectors 28, the electroluminescent components 56 can be located, in plan view, partially or entirely opposite the photodetectors 28.
In the embodiment represented in FIG. 7, the radiation detected by the image sensor 14 is that supplied by the source 42 and can be in a wavelength range different from the radiation emitted by the display screen 52. According to another embodiment, the source 42 is not present. In this case, the radiation detected by the image sensor can correspond to the radiation emitted by the electroluminescent components 56 of the display screen 52 or by some of them. In particular, for the application for capturing fingerprints, the display screen 52 can emit radiation which is reflected on the object 12, the radiation
B16100 - Reflected angular filtering being angularly filtered by the angular filter 16 and detected by the image sensor 14. According to one embodiment, for the application for capturing fingerprints, only electroluminescent components 56 of the screen d display 52 emitting the same color, for example blue light, are activated.
FIGS. 10 and 11 are respectively a sectional view and a top view, partial and schematic, of an embodiment of the angular filter 16.
In the present embodiment, the angular filter 16 comprises a support 60 and walls 62 resting on the support 60 and delimiting holes 64. The height of the walls 64 measured from the support 60 is called h. The support 60 is in one material at least partially transparent to the radiation picked up by the photodetectors 28. The walls 62 are opaque to the radiation detected by the photodetectors 28, for example absorbing and / or reflecting with respect to the radiation detected by the photodetectors 28. According to one embodiment, the walls 62 are absorbent in the visible and / or near infrared and / or the infrared.
In Figure 10, the holes 64 are shown with a square cross section. In general, the cross section of the holes 64 in the top view can be circular, oval or polygonal, for example triangular, square or rectangular.
According to one embodiment, the holes 64 are arranged in rows and columns. The holes 64 may have substantially the same dimensions. We call w the width of a hole 64 measured in the direction of the rows or columns. According to one embodiment, the holes 64 are arranged regularly in the rows and in the columns. The step of repeating the holes 64 is called p, that is to say the distance in top view of the centers of two successive holes 64 of a row or of a column.
The angular filter 16 shown in FIGS. 10 and 11 only allows the rays of the incident radiation to pass
B16100 - Angular filtering whose incidence relative to the support 60 is less than a maximum angle of incidence a, which is defined by the following relation (1):
tan a = w / h (1)
The smaller the w / h ratio, the smaller the maximum angle of incidence a. The zero incidence transmittance of the angular filter 16 is proportional to the ratio between the transparent surface in top view and the absorbent surface of the angular filter 16. For applications with low light level, it is desirable that the transmittance is maximum to increase the amount of light collected by the image sensor
14. For applications with high light level, the transmittance can be reduced so as not to dazzle the image sensor 14.
According to one embodiment, the photodetectors 28 can be distributed in rows and columns. According to one embodiment, the pitch p of the holes 64 is smaller than the pitch of the photodetectors 28 of the image sensor 14. In this case, several holes 64 may be located opposite a photodetector 28. According to one mode of embodiment, the pitch p of the holes 64 is identical to the pitch of the photodetectors 28 of the image sensor 14. The angular filter 16 is then preferably aligned with the image sensor 14 so that each hole 64 faces a photodetector 28. According to one embodiment, the pitch p of the holes 64 is greater than the pitch of the photodetectors 28 of the image sensor 14. In this case, several photodetectors 28 may be located opposite a hole 64.
The h / w ratio can vary from 1 to 10. The pitch p can vary from 10 pm to 30 pm, for example around 15 pm. The height h can vary from 1 μm to 1 mm, preferably from 20 μm to 100 μm. The width w can vary from 5 μm to 30 μm, for example approximately 10 μm.
The substrate 60 may be made of a transparent polymer, in particular of poly (ethylene terephthalate) PET, poly (methyl methacrylate) PMMA, cyclic olefin polymer (COP). The thickness of the substrate 60 can vary from 1 to 100. The substrate 60 can
B16100 - Angular filtering correspond to a color filter, a polarizer, a half wave or a quarter wave wave. The support 60 may also correspond to the image sensor 14 or to a protective layer covering the image sensor 14.
The holes 64 may be filled with air or filled with a material at least partially transparent to the radiation detected by the photodetectors 28, for example polydimethylsiloxane (PDMS). As a variant, the holes 64 can be filled with a partially absorbent material in order to chromatically filter the rays angularly filtered by the angular filter 16. The angular filter 16 can then also play the role of a colored filter. This makes it possible to reduce the thickness of the system compared to the case where a color filter distinct from the angular filter 16 is present. The partially absorbent filler material may be a colored resin or a colored plastic material such as PDMS.
The filling material for the holes 64 can be adapted in order to have an adaptation of refractive index with the upper layer in contact with the angular filter 16 or else to stiffen the structure and improve the mechanical strength of the angular filter 16.
In the embodiment illustrated in FIGS. 10 and 11, the walls 62 are entirely made of an absorbent material at least for the wavelengths to be angularly filtered. The walls 62 can be of colored resin, for example a colored or black SU-8 resin. By way of example, the walls 62 can be made of a black resin absorbing in the visible and near infrared range. According to another example, the walls 62 can be of colored resin absorbing visible light of a given color, for example blue light, in the case where the source 42 emits light of given color, in the case where the source 42 is polychromatic and that the image sensor 14 is sensitive only to the light of given color or in the case where the source 42 is polychromatic, that the image sensor 14 is
B16100 - Angular filtering sensitive to visible light and that a filter of the given color and interposed between the angular filter 16 and the object to be detected.
One embodiment of a method for manufacturing the angular filter 16 shown in FIGS. 10 and 11 comprises the following steps:
depositing a layer of colored resin on the support 60 whose thickness is substantially equal to the height h;
printing of the patterns of the walls 62 in the resin layer by photolithography; and development of the resin layer to keep only the walls 62.
Another embodiment of a method for manufacturing the angular filter 16 shown in FIGS. 10 and 11 comprises the following steps:
forming a mold in transparent resin, by photolithography steps, of shape complementary to the desired shape of the walls 62;
filling the mold with the material making up the walls; and removing the structure obtained from the mold.
Another embodiment of a method for manufacturing the angular filter 16 shown in FIGS. 10 and 11 comprises the perforation of a colored film of thickness h, for example a film of PDMS, PMMA, PEC, COP. The perforation can be carried out using a micro-perforation tool comprising for example micro-needles to obtain the dimensions of the holes 64 and the pitch of the holes 64 desired.
According to one embodiment, the angular filter 16 is formed directly on the image sensor 14, the support 60 then being able to correspond to the image sensor 14 or to a protective layer covering the image sensor. According to another embodiment, the angular filter 16 is formed separately from the image sensor 14. The angular filter 16 is then subsequently fixed to the image sensor 14, for example by lamination. The thickness of the substrate 60 is then preferably less than
B16100 - Angular filtering pm, and the substrate 60 is at least partially transparent to the wavelengths of interest to be measured by the image sensor
14.
Figure 12 is a sectional, partial and schematic view of an alternative embodiment of the walls 62 of the angular filter 16 shown in Figures 10 and 11 in which each wall 62 comprises a core 66 made of a first material at least in part transparent to the radiation detected by the image sensor 14 and covered with a layer 68 opaque to the radiation detected by the photodetectors 28, for example absorbing and / or reflecting with respect to the radiation detected by the photodetectors 28. The first material may be a resin. The second material can be a metal, for example aluminum (Al) or chromium (Cr), a metal alloy or an organic material.
One embodiment of a method for manufacturing the angular filter 16 shown in FIGS. 10 and 11 comprises the following steps:
depositing a transparent resin layer on the support 60, for example by spinning or by die coating (in English slot die coating);
printing of the patterns of the walls 62 in the resin layer by photolithography;
development of the resin layer to keep only the hearts 66 of the walls 62; and formation of the layer 68 on the hearts 66, in particular by a selective deposition, for example by evaporation, of the second material only on the hearts 66, or by deposition of a layer of the second material on the hearts 66 and on the support 60 between the hearts 66 and by removing the second material present on the support 60.
Figure 13 is a sectional, partial and schematic view of another embodiment of the angle filter
16. The angular filter 16 comprises the structure shown in FIGS. 10 and 11 and also comprises, for each hole 64,
B16100 - Angular filtering of a microlens 70 resting on the tops of the walls 62 and covering the hole 64.
Each microlens 70 advantageously makes it possible to increase the collection of rays of the incident radiation whose incidence is less than a desired maximum angle of incidence but which would be blocked by the walls of the walls 62 in the absence of the microlens 70. Such an embodiment is particularly suitable for applications in which the light level is low, such as the capture of fingerprints through the display screen 52. The microlenses 70 can be made of silica or PMMA. The material for filling the holes 64 may be the same as the material making up the microlenses 70.
The pitch of the microlenses 70 may be the same as the pitch of the photodetectors 28 or smaller. In the presence of microlenses 70, the holes 64 of the angular filter 16 act essentially as an optical micro-diaphragm between the microlenses 70 and the image sensor 14 so that there is less stress on the aspect ratio w / h holes 64 with respect to the case where the microlenses 70 are not present. The maximum angle of incidence is determined by the width w of the holes 64 and the curvature of the microlenses 70.
Figure 14 is a sectional view, partial and schematic, of a variant of the embodiment shown in Figure 13 in which the cross section of the holes 64 is not constant, the cross section decreasing as the moving away from the microlenses 70. There are shown, in the left part of FIG. 14, light rays in normal incidence which are not blocked by the angular filter 16 and, in the right part of FIG. 14, light rays in oblique incidence which are blocked by the angular filter 16.
Figure 15 is a sectional view, partial and schematic, of a variant of the embodiment shown in Figure 13 in which the walls 62 are formed in a thin layer located substantially at the focal plane of the
B16100 - Angular microlens filtering so that each hole 64 is centered substantially on the focal point of the associated microlens 70. Light rays in normal incidence have been shown in the left part of FIG. 15 which are not blocked by the angular filter 16 and, in the right part of FIG. 15, light rays in oblique incidence which are blocked by the filter angular 16. This arrangement of apertures at (or close to) the focal plane makes it possible to maintain the angular selectivity of the filter without reducing the effective sensitivity of the pixel by reducing its active surface.
An embodiment of a method for manufacturing the angular filter 16 shown in FIG. 14 or 15 comprises the following steps:
formation of microlenses on the upper face of a transparent support, in particular by printing techniques;
forming a layer of a positive photosensitive resin on the underside of the support; and forming holes 64 in the layer by exposing the photosensitive resin by collimated light through the mask formed by the array of microlenses 70 and removing the exposed portions of the resin.
This production method makes it possible to automatically align the microlenses 70 with the holes 64.
FIG. 16 is a partial and schematic sectional view of a variant of the embodiment shown in FIG. 13 in which the walls 62 include flanges 72 on which the microlenses 70 rest and include end portions 74 which are 'extend from the flanges 72 between the microlenses 70. This makes it possible to reduce the crosstalk between neighboring microlenses 70.
FIG. 17 is a partial and schematic sectional view of another embodiment of the angular filter 16 in which the angular filter 16 comprises a plate of optical fibers. The optical fiber plate comprises optical fibers 76 whose optical axes are substantially parallel
B16100 - Angular filtering and oriented parallel to the axis of the zero incidence rays detected by the image sensor 14. The core 78 of each optical fiber 76 is a first transparent material for the radiation detected by the image sensor 74 The sheath 80 of each optical fiber 76 surrounds the core 78 and is made of a material having a refractive index lower than that of the core 78. The sheaths 78 of the optical fibers 76 can form a one-piece structure.
Particular embodiments have been described. Various variants and modifications appear to those skilled in the art. In particular, the angular filter 16 described above can also be used to collimate the radiation which passes through it. In addition, the angular filter can serve as a polarizing filter, the filter being formed by perforating a polarizing film or being formed on a polarizing layer. When the radiation reaching the angular filter is polarized, for example linearly, the direction of polarization of the polarizing film is chosen to be different from the direction of polarization of the radiation so that the radiation is substantially blogged by the polarizing film. It should be noted that a person skilled in the art can combine various elements of these various embodiments and variants without showing inventive step. In particular, the angular filters described in relation to FIGS. 10 to 17 can be implemented with the image enhancement system 10 represented in FIG. 1, the image enhancement filter 25 represented in FIG. 2 , the image enhancement filter 40 shown in Figure 4 or the display system shown in Figure 7.
B16100 - Angular filtering

权利要求:
Claims (21)
[1" id="c-fr-0001]
1. Image acquisition system (10; 25; 40) comprising:
- a source (22; 42) of a radiation (44);
- an image sensor (14) comprising a matrix of photodetectors (28) adapted to detect said radiation and comprising a face (15); and
- an angular filter (16), covering the image sensor, and adapted to block the rays of said radiation whose incidence relative to a direction orthogonal to the face is greater than a threshold and to allow rays of said radiation to pass through The incidence relative to a direction orthogonal to the face is less than the threshold.
2. Systemclaim 1, comp acquisitionin addition, picturesa coating according toement (18) the, at less partially transparent audit radiation (44) and covering the sensor of images (14), the filtered angular (16) being interposed between the coating and the sensor of images. 3. System acquisition pictures according to the
claim 2, wherein the source (42) is adapted to emit said radiation (44) into the coating (18) from the periphery of the coating, the coating acting as a waveguide for said radiation.
[2" id="c-fr-0002]
4. An image acquisition system according to any one of claims 1 to 3, in which the radiation (44) is in the visible range and / or in the infrared range.
[3" id="c-fr-0003]
5. Image acquisition system according to any one of claims 1 to 4, in which the angular filter (16) comprises a matrix of holes (64) delimited by walls (62) opaque to said radiation (44) or of a polarizing material, the holes being filled with air or a material at least partially transparent to said radiation.
[4" id="c-fr-0004]
6. Image acquisition system according to claim 5, in which, for each hole (64), the ratio between the height of the hole, measured perpendicular to the face
B16100 - Angular filtering (15), and the width of the hole, measured parallel to the face, varies from 1 to 10.
[5" id="c-fr-0005]
7. The image acquisition system according to claim 5 or 6, in which the holes (64) are arranged in rows and in columns, the pitch between adjacent holes in the same row or in the same column varying from 10 pm to 30 pm.
[6" id="c-fr-0006]
8. An image acquisition system according to any one of claims 5 to 7, in which the height of each hole (64), measured in a direction orthogonal to the face (15), varies from 1 pm to 1 mm. .
[7" id="c-fr-0007]
9. An image acquisition system according to any one of claims 5 to 8, in which the width of each hole (64), measured parallel to the face (15), varies from 5 pm to 30 pm.
10. System acquisition pictures according to 1 'a any of claims 5 to 9, in which the walls (62) are all in one material opaque to said radiation. 11. System acquisition pictures according to 1 'a any of claims 5 to 9, in which each wall '' (62) includes a heart ( 66) in a transparent material audit radiation (44) covered with a diaper (68) opaque audit radiation. 12. System acquisition pictures according to Moon any of claims 5 to 11 , including, in addition , lenses (70) covering the holes ( 64). 13. System image acquisition according to the
claim 12, comprising, for each hole (64), a lens (70) covering the hole and in contact with the walls (62).
[8" id="c-fr-0008]
14. An image acquisition system according to any one of claims 1 to 13, in which the photodetectors (28) comprise organic photodiodes.
[9" id="c-fr-0009]
15. Display system (50) comprising the image acquisition system according to any one of claims 1 to 14 and further comprising a display screen (52), the filter
B16100 - Angular angular filtering (16) being interposed between the display screen and the image sensor (14).
[10" id="c-fr-0010]
16. The display system as claimed in claim 15, in which the display screen (52) comprises a matrix of light-emitting components (56) and in which the photodetectors are offset relative to the light-emitting components (56) according to a direction perpendicular to the face (15).
[11" id="c-fr-0011]
17. Display system according to claim 16, in which the light-emitting components (56) are separated from each other by intermediate zones (58) and in which the photodetectors (28) are located in the extension of said intermediate zones according to a direction perpendicular to said face (15).
electroluminescent claims 16
[12" id="c-fr-0012]
18. The display system as claimed in claim 15, in which the display screen (52) comprises a matrix of electroluminescent components (56), in which the electroluminescent components are at least partially transparent to radiation (44) and in which the electroluminescent components are located at least partially opposite the photodetectors (28) in a direction perpendicular to said face (15).
[13" id="c-fr-0013]
19. A display system according to any one of 18, wherein the components (56) include organic light emitting diodes.
[14" id="c-fr-0014]
20. Use of the display system (10) according to any one of claims 15 to 19 for the detection of at least one fingerprint of a user.
[15" id="c-fr-0015]
21. Method for manufacturing an image acquisition system, comprising the following steps:
- providing a source (22; 42) of radiation (44);
- forming an image sensor (14) comprising an array of photodetectors (28) adapted to detect said radiation and comprising a face (15); and
- forming an angular filter (16), covering the image sensor, and adapted to block the rays of said radiation,
B16100 - Angular filtering the incidence relative to a direction orthogonal to the face is greater than a threshold and to let through rays of said radiation whose incidence relative to a direction orthogonal to the face is less than the threshold.
[16" id="c-fr-0016]
22. The method of claim 21, wherein the angular filter (16) comprises a matrix of holes (64) delimited by walls (62) opaque to said radiation (44), the formation of the angular filter (16) comprising the following steps :
forming a layer of a photosensitive resin; and forming the walls by etching the layer by photolithography.
[17" id="c-fr-0017]
23. The method of claim 22, wherein the photosensitive resin is a black or colored resin.
[18" id="c-fr-0018]
24. The method of claim 21, wherein the angular filter (16) comprises a matrix of holes (64) delimited by walls (62) opaque to said radiation (44), the formation of the angular filter (16) comprising the following steps :
formation of a transparent resin mold, by photolithography steps, of shape complementary to the desired shape of the walls;
filling the mold with the material making up the walls; and removing the structure obtained from the mold.
[19" id="c-fr-0019]
25. The method of claim 21, wherein the angular filter (16) comprises a matrix of holes (64) delimited by walls (62) opaque to said radiation (44), each wall comprising a core (66) made of a transparent material at said radiation covered with a layer (68) opaque to said radiation, the formation of the angular filter (16) comprising the following steps:
forming a layer of a photosensitive resin transparent to said radiation;
etch the layer by photolithography according to the desired shape of the walls; and
B16100 - Angular filtering cover the structure obtained with the opaque layer on said radiation.
[20" id="c-fr-0020]
26. The method of claim 21, wherein the formation of the angular filter (16) comprises the perforation of
5 micrometric size holes in a black or colored film.
[21" id="c-fr-0021]
27. The method of claim 26, wherein the holes are drilled by means of micrometric size needles.
B16100

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法律状态:
2018-08-16| PLFP| Fee payment|Year of fee payment: 2 |

2018-09-07| PLSC| Publication of the preliminary search report|Effective date: 20180907 |

2019-08-26| PLFP| Fee payment|Year of fee payment: 3 |

2020-08-26| PLFP| Fee payment|Year of fee payment: 4 |

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2021-08-30| PLFP| Fee payment|Year of fee payment: 5 |

优先权:

申请号 | 申请日 | 专利标题

FR1751789|2017-03-06|

FR1751789A|FR3063564B1|2017-03-06|2017-03-06|INTEGRATED FINGERPRINT SENSOR IN A DISPLAY SCREEN|JP2019548435A| JP2020511713A|2017-03-06|2018-03-06|Image acquisition system|

US16/491,830| US11037012B2|2017-03-06|2018-03-06|Image acquisition system|

CN201880030050.0A| CN110603579A|2017-03-06|2018-03-06|Image acquisition system|

KR1020197029231A| KR20190140439A|2017-03-06|2018-03-06|Image acquisition system|

EP18712962.2A| EP3593342A1|2017-03-06|2018-03-06|Image acquisition system|

PCT/FR2018/050516| WO2018162842A1|2017-03-06|2018-03-06|Image acquisition system|

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