Method and system for selectively adjusting pixels in an optical module to correct geometric defects due to manufacturing tolerances

Abstract

To provide a luminous motor-vehicle system capable of compensating for undesirable movement or deformation effects in a projected image caused by manufacturing tolerances of an optic.SOLUTION: An optical module 1 includes an imaging device provided with a pixelated spatial modulator 3, which is illuminated by a source 2, and a projecting optic 18. A control unit 16 for controlling the pixelated spatial modulator 3 receives first display commands F1 that are representative of an image to be projected. The control unit 16 converts each first display command F1 into a second display command F2 taking into account correction parameters, which are predefined on the basis of an identification of geometric defects specific to the projecting optic 18. The control unit 16 controls the pixelated spatial modulator 3, which may be a digital micromirror device 6, depending on the second display commands F2 in order that an image F3 actually projected by the imaging device corresponds to the image to be projected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the spatial resolution of vehicle lighting fixtures into pixels using modulators, for example in the form of a Digital Micromirror Device (DMD) having controllable micromirrors. More specifically, the present invention relates to methods and systems in the automotive industry that allow pixels of an image to be projected to be adjusted to compensate for geometric imperfections inherent in the design or assembly of the forming optics in the projected image. [Background technology]

[0002] Automotive lighting and / or signaling devices are known that include a light source and a digital micromirror device or similar modulator that can resolve a light beam into pixels distributed in two dimensions. The digital micromirror device is typically used to reflect a light beam originating from the light source toward an optical component that shapes the light beam. The optical component is intended to project an image formed on the digital micromirror device, forming an output light beam. This light beam can, for example, illuminate a road along which a vehicle equipped with the lighting and / or signaling device is traveling, or perform a signaling function.

[0003] Such lighting devices are designed using mass production methods: there is inevitably a play between the components of the lighting and / or signaling device, on the one hand to allow for easy assembly, and on the other hand because the parts are generally not machined but molded from plastic to reduce manufacturing costs.

[0004] It must be emphasized in particular how difficult it is to perfectly align a spatially pixelated modulator (also called a high-resolution pixelated spatial modulator due to the large number of pixels that can be activated or deactivated) with the projection optics, which usually take the form of at least one lens. Since the objective lenses used for the projection function have a high numerical aperture, a lateral offset of up to 50 μm from the optical axis significantly reduces the projection quality of the image. Furthermore, in practice, dynamically aligning the positions of elements (forming part of digital micromirror devices or similar modulators) during the manufacture of the optical module is cumbersome.

[0005] Manufacturing and positioning tolerances of the elements that make up the optical system can cause geometric defects that are perceptible on an internal projection screen, if the lighting and / or signaling device has one, or on a screen placed external to the lighting and / or signaling device, if the lighting and / or signaling device is designed to project light directly onto the road and does not have an internal projection screen.

[0006] Furthermore, projection lenses often produce other aberrations that blur the image, an effect exacerbated by the positional offsets mentioned above.

[0007] Such geometrical defects become severe when high numerical apertures (wide-angle optics) are required, for example, with a factor of about or about 0.7. Therefore, there is a need to provide better optical systems, especially for high numerical apertures, that do not use complex and expensive components and that align elements with one another without requiring adjustment procedures that are tedious and expensive to perform.

[0008] The present invention therefore aims to prevent manufacturing tolerances during production from causing geometric defects (significant deformation or excessive movement relative to the optical axis) in the formed light beam, for example the light beam that is projected onto a projection screen before leaving the vehicle or the light beam that is projected directly onto the road. Summary of the Invention

[0009] To this end, the present invention provides a method for correcting geometrical imperfections in a light beam projected by a motor vehicle optical module, comprising: The optical module includes: an imaging device comprising a high-resolution pixelated spatial modulator and projection optics; a light source for generating light directed to said modulator; optionally a projection screen suitable for receiving the light beam transmitted by said projection optics; Including, The method comprises: receiving a first command to display an image to be projected, the first command being directed to said high resolution pixelated spatial modulator; - transforming said first display command into a second display command taking into account the modification parameters; comprising the steps of: The correction parameters are predetermined based on recognition of geometric defects specific to the projection optical components, thereby controlling the modulator so that the image actually projected using the imaging device matches the image to be projected better than if the correction parameters were not taken into account.

[0010] Such a configuration allows illumination to be controlled and adapted by creating imperfection compensation effects that reposition certain portions of the light beam and / or modify the aspects of the light beam. The method allows for adapting the light beam by selectively activating or deactivating pixels of the modulator and selectively modulating the duration of activation of these pixels without resorting to mechanical devices or additional parts that may affect volume.

[0011] It will be understood that the geometric defects specific to the projection optics correspond to all defects of the high-resolution pixelated spatial modulator that are downstream in the direction of light propagation within the optical module, in particular slight defects in the alignment of one or more components of the projection optics (defects related to tolerances, especially lateral tolerances) and structural defects inherent in the complex shape of the projection lens.

[0012] The method allows for the use of an efficient method for mass-producing optical modules while maintaining the current tolerance levels that facilitate assembly and minimize manufacturing constraints and costs of optical elements (e.g., perfect lenses are expensive, especially when high numerical aperture lenses are an issue).

[0013] Naturally, a better match to the desired image will result in fewer shifts and anomalies that affect the perception of the projected image, typically reducing geometric shifts and variations in line thickness measured across multiple sections of the image.

[0014] Another advantage of the method is that the geometric defect recognition process is performed only once, and therefore no further comparison steps are required during operation.

[0015] According to one option, in particular the second display command differs from the first display command in the selective activation of all or part of columns of pixels, said columns being defined by the modulators in a peripheral zone (on the border or to the side of the border).

[0016] According to one characteristic, - a lateral shift of the profile of the light beam transmitted by the projection optics, and - deformation of the profile of the light beam transmitted by the projection optics, The correction parameters are adapted to change the actuation status of pixels defined by the modulator so as to compensate for defects in at least one of the above.

[0017] According to one feature, the correction parameters compensate for the effects of distortion by determining position shifts to be selectively applied to pixel zones in the modulator that have been previously identified in a calibration step that allows for geometric imperfections to be recognized. In practice, these are typically, due to the individual characteristics of the modulator, not only shifts but also variations in brightness, i.e., ultimately stretching or shrinking effects that result in variations in grayscale levels when a digital image is taken as an analogy. It should be noted that the expression grayscale level applies to variations in brightness that are independent of the actual color of the light beam. It therefore corresponds to a representation of the brightness of the light beam, whether the light beam is white or colored, e.g., red, amber, or any other color.

[0018] According to one feature, the modification parameters and / or the second display command are stored in a memory accessible to a control unit, which typically can activate the second display command.

[0019] It will be appreciated that the memory to which the control unit has access may store data indicative of the calibration, in particular the correction parameters, and / or one or more predetermined images corresponding to the correction results.

[0020] According to one feature, the correction parameters are obtained after the following steps: - Using at least one test pattern, a step of obtaining a set of sequential shift information regarding differences in position and shape that affect, for example, the projected test pattern (projection onto a projection screen inside the module that is suitable for receiving the light beam transmitted by the projection optics, or projection directly onto the outside). - A step of calculation of the correction parameters to be applied to the light beam transmitted by the modulator according to a set of sequential shift information. - activating or deactivating one or more pixels of the modulator depending on the modification parameters. This typically relies on a stock of pixels that are used when the system is not properly adjusted, and these pixels are used to correct when the projected image needs to be moved (shift, tolerance) and / or expanded (distortion).

[0021] According to one feature, to compensate for distortions (related to the optical design or lateral play), the pixels of the modulator are divided into zones, and the shift to be applied to obtain the correct projected shape is calculated for each zone. This zoning can define at least four zones (optionally of equal area), preferably at least, for example, nine zones.

[0022] According to one feature, commands for displaying the test pattern are stored in a memory accessible to the control unit, the test pattern being displayed in a prior step of recognizing and defining the correction parameters.

[0023] According to one feature, in the modulator, the test pattern extends over a central area and at least four additional areas of equal size formed around the central area, It will be appreciated that a portion of the test pattern is located at a distance from the central zone of the modulator's pixels, so that the particular defect to which the correction pattern corresponds can be recognized.

[0024] According to one feature blurring, to compensate for the blurring, a test pattern defining the desired feature is used, and a reduction in "active" pixels to be applied to the modulator to project a test pattern having the same feature boundary as the desired feature is calculated, along with a ratio of "active / inactive" pixels to be applied to compensate for the reduction in flux corresponding to the reduction in the number of pixels used. More generally, certain lines are thickened so that when projected, they have a desired thickness. This improves certain contours, particularly contours parallel to the lines of the test pattern.

[0025] The method according to the invention may comprise one or more of the following features: The modulator has a single power supply input and can selectively activate a large number of pixels, up to 1000 or more. - Actuation is selectively achieved through control of the movement of a movable element provided on each micromirror of the digital micromirror device (each movable micromirror has at least two positions, one of which is an actuated position and the other of which is a non-actuated position, with respect to illumination). The correction parameters are suitable for changing the duration or frequency of activation of the pixels of the modulator (brightness or greyscale controllable) so as to compensate for loss of clarity of the projected image, especially near the outer edges of the light beam transmitted by the projection optics. In most cases, loss of clarity can be defined as a widening of features accompanied by the appearance of at least one blurred edge. The process of recognition of all or part of the geometric defects comprises the following steps: a) turning on a light source; b) actuating a defined series of pixels by a modulator to create a test pattern distributed over various pixel-containing zones of the module, the series of pixels having a continuous or discontinuous contour that may define predetermined shape parameters of the test pattern; c) defining all or part of the modification parameters using test patterns; Step c) comprises at least one of the following substeps: i) comparing shape parameters of the projected test pattern with predetermined shape parameters; ii) defining correction parameters depending on the comparison result obtained in sub-step i). Step c) comprises the following sub-steps: - estimating a parameter indicative of blur in the projected test pattern; - applying at least one blur compensation in the correction parameters depending on whether the estimated parameters exceed a clarity threshold or not.

[0026] According to one particular embodiment, the light beam transmitted from the modulator is segmented and includes at least one break.

[0027] According to one particular example, the light beam output from the optical module is a segmented low beam (the section is, for example, a horizontal low beam section formed by one or more upper edges of one or more segments of the light beam) or a segmented high beam (the section is, for example, a vertical section formed by one or more lateral edges of one or more segments of the light beam).

[0028] According to one option, the segmented light beam comprises at least one luminous line segment, e.g. resulting from horizontally juxtaposed or partially overlapping segments, each luminous segment corresponding to all or part of a column of selectively actuatable pixels, activation of that column or part of the column of pixels causing said luminous segment to light up.

[0029] According to one particular example, the light source is an electroluminescent element or a group of electroluminescent elements, for example one or more LEDs, each of which may be connected to a control circuit belonging to the control unit.

[0030] It will be appreciated that control of the pixels by the control unit allows for flexibility of adjustment, and this control allows for fine tuning of the projected image (which may be projected infinitely from the projection optics or projection screen).

[0031] Another object of the present invention is to provide a lighting system for at least partially correcting undesired deformations in a projected light beam, said deformations resulting from specific manufacturing tolerances of optical modules of the type comprising high-resolution pixelated spatial modulators.

[0032] For this purpose, a lighted motor vehicle system is provided that allows the implementation of the method described above, comprising: The system comprises: an optical module, an imaging device comprising a high-resolution pixelated spatial modulator and projection optics; a light source for generating light directed to said modulator; - a projection screen, optionally suitable for receiving the light beam transmitted by said projection optics (no screen is provided if the light beam is intended to be projected indefinitely, i.e. very far from the light emitting system - at least 10 times, in particular 20 times, in particular 100 times the dimension of the light emitting system). an optical module comprising: a control unit of said modulator designed and arranged to control said modulator and suitable for receiving a plurality of first display commands, each first display command indicating an image to be projected; Including, the control unit comprises adjustment means for converting each first display command into a second display command taking into account the modification parameter; A system is provided in which the correction parameters are predetermined based on recognition of geometric imperfections specific to the projection optical components, and the control unit controls the modulator in response to a second display command so that an image actually projected using the imaging device better matches the image to be projected than if the correction parameters were not taken into account.

[0033] According to one particular embodiment, the high-resolution pixelated spatial modulator comprises a digital micromirror device, the micromirrors of which each have: a first position in which the micromirrors are arranged to reflect light rays from the light source or from a light emitting unit including the light source in the direction of the projection optics; a second position in which the micromirrors are arranged to reflect light rays from the light source or from a light emitting unit including the light source away from the projection optics (outside the entrance pupil of the projection optics); It is movable between.

[0034] According to one particular embodiment, the projection optics preferably defines a wide aperture angle, preferably for a numerical aperture greater than 0.5, preferably greater than 0.7.

[0035] A lighting system according to the present invention may include one or more of the following features. a high-resolution pixelated spatial modulator illuminated in an illumination zone by a light source and defining a set of pixels distributed in parallel columns of pixels, the spatial modulator being oversized so that at least a first column of pixels can optionally be initially positioned outside the illumination zone; - The peripheral zone allowing oversizing corresponds to an outer edge zone having a frame format that defines excess pixels at the top, bottom, left, and right of the nominal area sufficient to produce the desired image in the absence of geometric defects (in the case of digital micromirror devices, the advantage of this oversizing is also the possibility, if desired, of limiting the heat generated by illuminating the non-reflective edges of the device). - The active area in which the pixels are defined may have excess pixels in one or more peripheral zones relative to the pixel format defined in each of the first display commands (this makes it possible to correct centrality defects or barrel distortions that require the image to be enlarged in the corners, or pincushion distortions that require the image to expand towards the centre of its edges). - the control unit is suitable for selectively controlling the high-resolution pixelated spatial modulator so as to selectively activate (it is to be understood that the term "activate" may simply mean that one or more pixels / mirrors are brought into an activated state) one or more peripheral zones arranged along the edge or edge sections of the active area in which the pixels are defined according to the modification parameters. - said imaging device is suitable for projecting a segmented output beam having at least one split; The pixels of the high-resolution pixelated spatial modulator are distributed along or parallel to a first axis to define columns parallel to the first axis. These columns are distributed at different levels along a second axis perpendicular to the first axis. In an operating configuration of a lighting system for a motor vehicle, the first axis corresponds to a horizontal axis and the second axis corresponds to a substantially vertical axis. The control unit has access to a memory for storing information indicative of the modification parameters and / or the second display command.

[0036] According to another special feature, the lighting system comprises two optical modules, Each optical module is an imaging device comprising a high-resolution pixelated spatial modulator and projection optics; a light source for generating light directed to said modulator; Including, Each light beam transmitted by one of the projection optics is received at at least one projection screen.

[0037] Preferably, the control unit is suitable for controlling the modulator of each of the two optical modules and for taking into account a first set of correction parameters corresponding to a first of the two optical modules and a second set of correction parameters corresponding to a second of the two optical modules, Typically, the first set of correction parameters are predefined based on recognition of geometric imperfections specific to the projection optics of the first optical module, while the second set of correction parameters are predefined based on recognition of geometric imperfections specific to the projection optics of the second optical module.

[0038] Furthermore, a lighting and / or signaling lamp of a motor vehicle for projecting at least one light beam, comprising: - housing; - a closed outer lens; a lighting system according to the invention, A lamp comprising:

[0039] Furthermore, - Two lamps and - two headlamps, or - lamps and headlamps, 1. A light emitting assembly having a first part and a second part formed by: The light emitting assembly may be provided as comprising a light emitting system having two optical modules as described above, one of the optical modules being distributed in the first component and the other in the second component.

[0040] Other characteristics and advantages of the invention will become apparent from the description of several embodiments thereof given as non-limiting examples with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0041] [Figure 1] 1 shows a schematic diagram of an example of an illuminated motor vehicle headlamp with an optical module and with correction of geometric imperfections; [Figure 2] FIG. 2 is a schematic cross-sectional view showing details of a digital micromirror device forming the high-resolution pixelated spatial modulator used in the optical module of FIG. 1. [Figure 3] A simplified diagram showing the parameterization of a modulator pixel via coordinates along two axes of the area of ​​the modulator that is activated to generate the output light of the optical module, so that the actual projected image can be adjusted. [Figure 4] 1 is a diagram of steps performed in a method for correcting geometric defects according to the present invention; [Figure 5A] Schematic diagram of the correct emission distribution when the optical component has no significant geometric defects. [Figure 5B] 1 shows a schematic diagram of the luminous intensity distribution that must actually be parameterized due to geometrical imperfections in order to obtain the desired luminous intensity representation. [Figure 6A] FIG. 10 shows an example of the deformation observed between the commanded image and the image that appears on the projection screen of the optics module in the absence of any modification. [Figure 6B] FIG. 6B shows an example of the distortion observed through the detail of FIG. 6A, along with the effect of blurring that thickens certain features of the projected image. DETAILED DESCRIPTION OF THE INVENTION

[0042] In the different drawings, the same reference signs are used to denote the same or similar elements. For ease of understanding, the size of some elements may be exaggerated in the drawings.

[0043] 1 shows a first embodiment of an optical module 1 that can form or form part of a light-emitting motor vehicle system 5, such as a headlight or taillight. The optical module 1 forms a light-emitting device that is configured to perform one or more functions, some of which are subject to regulations regarding luminous intensity.

[0044] As shown, optical module 1 comprises a lighting unit 20, a digital micromirror device (DMD) 6, a control unit 16, e.g., in the form of a controller 16, capable of controlling micromirrors 12 of digital micromirror device 6, and projection optics 18 (or forming optics). Control unit 16 may be selectively spaced apart, e.g., to be capable of controlling multiple optical modules 1. It will be appreciated that light emitting automotive system 5 may receive centrally generated commands, e.g., corresponding to commands relating to lighting and / or signaling functions or other luminosity functions.

[0045] Suitable luminous functions associated with the optical module 1 are illumination and / or signaling functions visible to the human eye, which may be subject to one or more regulations specifying requirements regarding color, intensity, spatial distribution on a photometer test screen, or the visibility range of the emitted light.

[0046] The optical module 1 is for example a headlamp 10 - a lighting device forming a headlight, which is configured to provide one or more luminous intensity functions, for example selected from the following functions: low beam, high beam and fog lamp.

[0047] Alternatively or in parallel, the optical module 1 is a signaling device intended to be arranged at the front or rear of a motor vehicle.

[0048] When intended to be disposed in the front, the luminous functions that can be performed using the optical module 1 (in addition to the optional role that the optical module 1 plays as a lighting device) include a turn indication function, a daytime running light (DRL) function, a forward illuminating indicator function, a position indicator function, and a side marker function.

[0049] When intended for rear mounting, such luminous functions include a function to indicate that the vehicle is backing up, a fog lamp function, a turn indicator function, a rear light indicator function, a position indicator function, and a side marker function.

[0050] A light source 2 (forming part of unit 20 in this example) is provided for generating a light beam forming the emitted light R1 which is directed towards the digital micromirror device 6. The light source 2 may consist of electroluminescent elements such as light emitting diodes (i.e. LEDs) or a matrix array of LEDs. In the case of a group of electroluminescent elements, these may preferably be arranged together in the same zone and linked to a single light source. If necessary, the emitted light R1 may also be formed by a laser diode coupled to a collimator system and optionally a wavelength conversion device.

[0051] For rear light indicator function, the light source 2 may be red. For front light function, the light source 2 is preferably white.

[0052] Although a digital micromirror device 6 is shown in the drawings, it will be understood that the light emitted by the light source 2 can be directed by suitable optical components to any type of high-resolution pixelated spatial modulator 3 capable of resolving the received emitted light R1 into pixels. In an alternative embodiment, an LCD pixel matrix array can be used, having active areas forming pixels on an optical surface. Specifically, a device employing a transmissive LCD screen can be employed. In this case, the optical path of the emitted light R1 can be replaced by the optical path inside the LCD device, without any necessary deflection / defocusing. More generally, it will be understood that the first emitted light R1 can be received in an area that is very finely divided to define high-resolution pixels, typically greater than 1280 x 720 pixels, and whose structure allows modulation. Preferably, each pixel can change its state in a manner known per se.

[0053] The light emitting unit 20 may also be provided with a collimator lens 4 suitable for directing the emitted light R1 towards the modulator 3. This unit 20 may also comprise "imaging" optics to provide a convergent beam. In the example shown in Figure 1, a collimator lens 4 or set of collimator lenses is preferably used to receive the light of the light source 2, so that the collimated light is received at the substantially rectangular active surface of the digital micromirror device 6.

[0054] As a non-limiting example, the collimating effect can be achieved by a converging lens. In this case, the light source 2 is advantageously positioned near the object focal point of the converging lens to ensure that the light rays of the emitted light R1 propagating between the light-emitting unit 20 and the digital micromirror device 6 have a substantially beam shape. Alternatively or additionally, the light-emitting unit 20 includes a reflecting mirror. In this case, the light source 2 is positioned near the object focal point of the reflecting mirror.

[0055] The motor vehicle headlamp 10 shown in FIG. 1 may be housed in or bounded by a housing 14. The housing 14 as shown includes a body 14a that defines a hollow interior space for receiving at least a portion of the optical module 1. An at least partially transparent cover 14b is coupled to the body 14a to close the interior space. As shown, the cover 14b also defines a cavity that partially receives the optical module 1 and, in particular, all or a portion of the projection optics 18.

[0056] The cover 14b is made of, for example, plastic resin or other suitable plastic material. The illuminated headlamp 10 may include a plurality of optical modules 1 suitable for emitting adjacent light beams. These light beams preferably partially overlap. In particular, the lateral ends of adjacent light beams may overlap. Other light beam configurations are also possible, for example, by overlapping the lower edge of one light beam with the upper edge of another light beam, so as to digitally modify the light beams and obtain functions such as adaptive driving beam (ADB) or dynamic bending light (DBL).

[0057] Here, the projection optics 18 enable the reflected emitted light R2 to be formed after reflection from the digital micromirror device 6, which may define the output light beam 40. More generally, the imaging device provided in the optical module 1 includes a high-resolution pixelated spatial modulator 3 and the projection optics 18.

[0058] 1 and 3, the digital micromirror device 6 is, for example, rectangular. Thus, the digital micromirror device 6 extends primarily in a first extension direction between lateral ends 6a and 6b of the digital micromirror device 6. In a second extension direction, which may correspond to the vertical direction (height), there are likewise two opposing edges 6c, 6d, which are typically parallel to each other.

[0059] 2, the digital micromirror device 6 may optionally be coated with a layer CP to protect the micromirrors 12. This layer is transparent. The pivot axis of each micromirror 12 may allow rotation of, for example, plus or minus 10° relative to a nominal position with no rotation.

[0060] Referring to FIG. 1 , the digital micromirror device 6 is essentially defined by an electronic chip 7, in this example, attached to a printed circuit board 8 via a suitable socket 9. A cooling device, in this example a radiator 11, is attached to the printed circuit board 8 so as to cool the printed circuit board 8 and / or the chip 7 of the digital micromirror device 6. To cool the chip 7 of the digital micromirror device 6, the radiator 11 may have a protruding relief that passes through an opening in the printed circuit board 8 for the purpose of contacting the chip 7. The socket 9 passes through this protruding relief. Thermal grease, or other means for promoting heat exchange known to those skilled in the art, may be disposed between the protruding relief and the digital micromirror device 6.

[0061] In this example, a control unit 16 is connected to the digital micromirror device 6 or to another type of high-resolution pixelated spatial modulator 3, for example via a printed circuit board 8. The control unit 16 issues commands for changing the position of each of the micromirrors 12 of the digital micromirror device 6 in this example. In the case of an LCD pixel matrix array, the state of the pixels can also be controlled by the control unit 16. Such a control unit 16 forms part of the headlamp 10 and can be integrated into the housing 14 or can be separate and located remote from the optical module 1.

[0062] The control unit 16 can be considered to form part of the lighting system 5, which combines the functionality for modifying the display commands with the functionality for projecting light.

[0063] Figure 6A shows an example of the distortion observed in the prior art between image F1 transmitted to modulator 3 and image F3 appearing unmodified on the projection screen E1 of the optical module. Figure 6B further illustrates the blurring problem, particularly with non-uniform illumination, which creates thinner subzones 21 and thicker subzones 22.

[0064] As shown in Figure 1, control unit 16 is configured to at least partially correct distortions created by the imaging optics by generating display commands F2 that modify the pattern of pixels normally actuated on modulator 3 (the pattern corresponding to the initial display command, i.e., first display command F1 presented at the top of Figure 1). The second display command F2 takes into account correction parameters so as to compensate for distortions typically due to imperfections in the curvature of lenses or other optical elements.

[0065] For example, a normal vertical line, such as that appearing in the number "1," may be curved in a concave manner to the left when projected onto the projection screen E1 due to such distortion. To correct for this type of distortion, the corresponding pixels activated in the modulator 3 to form this vertical line are changed from pixels in a straight line to pixels that are curved in a concave manner to the right (or concave to the left, if other optical elements are present that reverse the direction of curvature perceived by the driver). Such changes are incorporated into the display command F2 in the form of correction parameters.

[0066] The degree of "curvature" or compensation for distortion of the imaging optics programmed into the pixels of the modulator 3 can be obtained using a test pattern M in an initial calibration phase 50 (see Figure 4) which allows correction parameters to be recognized and defined.

[0067] With respect to compensation for centrality defects (and potentially peripheral distortions), implementing this type of image distortion compensation requires a distribution of a larger number of pixels than would be required if no image distortion correction were applied.

[0068] Specifically, when a high-resolution pixelated spatial modulator 3 is illuminated by a light source 2 in an illumination zone bounded by an outer periphery, the modulator 3 may define a set of pixels 30 arranged in parallel columns of pixels. The set of pixels 30 may have an excess of pixels, resulting in at least one first column of pixels located beyond the outer periphery of the illumination zone. Therefore, the modulator 3 may be oversized, for example, by tens to hundreds of microns, to include such a type of pixel column on its periphery. This first column of pixels, located away from the symmetrical center point of the modulator 3, may not be used. However, due to its large size, another spaced-apart pixel column parallel and opposite to the first column may be used, if necessary, to compensate for geometric imperfections, particularly defects related to centrality that affect projection. Therefore, the second display command F2 may differ from the first display command F1 in the selective activation of all or part of such another spaced-apart pixel column. This is also applicable to compensating for defects in the centrality of the illumination zone of the modulator 3. The control unit 16 may also be able to compensate for defects in the centrality of the projection optics (rather than the upstream elements 4 and 2), in which case it is assumed that the entire device 6 is illuminated, i.e. including the spare pixels (which can then be corrected for distortions).

[0069] 1, the control unit 16 may comprise a memory 16a and adjusting means 17 for changing the operating state of the pixels defined by the modulator 3. In the case of the digital micromirror device 6, the adjusting means 17 allow for controllable movement of the micromirrors 12. As shown schematically in FIG. 2, only some of the micromirrors 12 having a first position actually deflect / redirect the emitted light R1 from the light source 2 or the light-emitting unit 20, thereby transmitting the light energy to the reflected emitted light R2 directed towards the projection optics 18. The other micromirrors 12 are either in an inactive second position (a position in which the light radiation is prevented from being collected by the projection optics 18) or are located outside the illumination zone of the modulator 3.

[0070] Here, in the digital micromirror device 6, each of the micromirrors 12 is a first position in which the micromirror 12 reflects the incident ray of emitted light R1 in the direction of the projection optics 18; a second position in which the micromirror 12 transmits, by reflection, the incident ray of emitted light R1 away from the projection optics 18, for example in the direction of a radiation absorption device 19 having a light-absorbing surface; It is movable between.

[0071] 3, the control unit 16 may define display commands corresponding to a pattern or image 25 on the device 6. Here, a cross shape is taken as an example, but examples could also be ring shapes, alphanumeric characters or other geometric elements that are easily presented in the form of coordinates (horizontal coordinates H1, H2, H3, H4, etc. and vertical coordinates V1, V2, V3, V4, etc., shown diagrammatically in FIG. 3) or vectors. Depending on the correction parameters taken into account by the control unit 16, the routine applied by the adjustment means 17 may consist of modifying the position or shape and / or adjusting the brightness in the outer edge zones of the pattern 25 so as to compensate for the distortions and anomalies recognized and calibrated in the recognition of geometric defects.

[0072] A table of vectors is typically determined in such a step for the purpose of selectively changing the states of the pixels of the modulator 3. In such a table of vectors, there may be listed those micromirrors 12 to be selectively deactivated, i.e., those micromirrors determined in the initial calibration step to correspond to "excess" light-reflecting zones; and, in addition, those micromirrors 12 to be selectively activated, which may be identified in the table in response to the determination of "deficient" light-reflecting zones in the initial calibration step.

[0073] In the case of using a digital micromirror device 6, the adjustment means 17 takes into account a table of vectors, by which the active pixel is adjusted. Typically, the memory 16a of the control unit 16 stores data indicative of position shifts induced by geometric imperfections specific to the projection optics 18. This data may already incorporate compensations to be applied to correct for such shifts, or the adjustment means may include a program to infer the compensations to be applied from this data. Such position shift data may form all or part of the correction parameters.

[0074] This data may involve a coefficient to be applied to the grayscale level, or a coefficient of a linear combination of the grayscale level values ​​of neighboring pixels that provides the grayscale level to be provided to the new pixel (shifted pixel). Typically, it can be assumed that the shift is calculated for each pixel individually and the coefficients are applied to the grayscale level by interpolation of values ​​found at several points in the test pattern M.

[0075] For defects related to centrality, FIG. 1 shows diagrammatically the inverse deformation that must be applied in the second display command F2 so as to simultaneously compensate for the type of deformation shown in FIG. 6A, which shows the case without correction.

[0076] 4, the method for correcting geometric defects in the light beam projected by the optical module 1 may comprise a calibration phase 50, preferably carried out prior to the first actual use of the optical module 1 in a motor vehicle. In this non-limiting example, the calibration phase 50 begins following a step 60 of powering up the optical module 1. In step 60, a first display command is sent to the modulator 3b. Here, this first command corresponds to a default command that does not take into account variations in the specific structure of the projection optics 18 or in the manner in which the projection optics 18 are mounted, and that is only appropriate in the absence of geometric defects.

[0077] The calibration phase 50 begins with step 51, in which a first command is received by the modulator 3. This is followed by step 52, in which a configuration of pixel usage is generated. Figure 4 shows an example in which the first display command essentially results in a shift related to a defect in terms of centrality. Step 53, in which the defect is recognized, can then be initiated. This step preferably uses a test pattern M observable on the projection screen E1.

[0078] Here, the term "test pattern" should be understood in its conventional sense in optics. Considered in the context of illumination resolved into pixels 30, a test pattern generally corresponds to a set of lines / pattern elements with different orientations and widths. Here, test pattern M is particularly useful for studying the effects of clarity limitations, deformations, and distortions observed when emitted light R2 is projected by projection optics 18.

[0079] In the calibration phase 50, the collection and analysis of information about position shifts and other anomalies is preferably done automatically, for example using sensors and image processing and defect recognition programs, by comparing expected and actually observed positions of points of interest in the test pattern M. The test pattern M is generated, for example, by activating a predetermined series of pixels having at least one continuous or discontinuous contour that may define the shape parameters of the test pattern M.

[0080] Alternatively, it is possible to generate a test pattern M that extends over the entire digital micromirror device 6 so as to recognize defects as completely as possible. In such a test pattern M, the transitions between dark or black pixels and light pixels are preferably numerous and distributed over the entire zone of pixels, which allows the generation of a pattern 25 that is significantly wider and typically more complex than the one shown by way of example in FIG.

[0081] In a defect recognition step 53, information about the shifts is collected to generate a set of shift information relating to the differences in position and shape affecting the test pattern M projected on the projection screen E1. Correction parameters can then be obtained in step 54. In step 54, correction parameters to be applied to modify the light beam transmitted from the modulator 3 are calculated according to the set of shift information.

[0082] The memory 16a can then be used to store information indicative of these correction parameters, which are then systematically taken into account for subsequent requests of the optical module 1 to alter the activation and deactivation of particular pixels of the modulator 3.

[0083] Typically, in steps 53 and 54, one or more shape parameters of the projected test pattern M can be compared with one or more predetermined shape parameters of the test pattern. The results of the comparison can define at least some of the correction parameters. Deformations of the image contours, such as local changes in curvature, orientation, or thickness (blurring), can also be compensated for. Therefore, it is possible to estimate parameters indicative of blurring in the projected test pattern M. For example, depending on whether the estimated parameters exceed a clarity threshold, a corresponding compensation can be incorporated into the correction parameters. This type of compensation can be applied on a zone-by-zone basis. When reducing the number of "active" pixels to limit the effect of blurring in a particular zone, the "active / inactive" pixel ratio in that zone can be recalculated to compensate for the flux reduction that accompanies the reduction in the number of used pixels. It is possible to modify the thickness of certain lines, which is advantageous for line drawings or text, for example.

[0084] If necessary, the correction parameters may also change the duration or frequency of activation of pixels 30 of modulator 3 to compensate for a decrease in brightness of the projected image F3, particularly near the outer edges of the light beam transmitted by the projection optics 18.

[0085] After these steps, the calibration phase 50 may end. Alternatively, the validity of the correction parameters may be tested by repeating steps 52 and 53, whereby the correction parameters may be optionally refined. Furthermore, the calibration phase may be divided into multiple sub-phases, especially if the optical module 1 has multiple operating modes that affect the shape, split, or uniformity of the desired output beam 40.

[0086] The optical module 1 can then be utilized in a vehicle, in particular an automotive vehicle, with a control unit 16. The control unit 16 controls the modulator 3 to systematically convert the first display commands into second display commands that take into account the correction parameters determined in the calibration phase 50.

[0087] 4, there may be the following steps 60, 61, in which the optical module 1 is activated and the modulator 3 receives a first command (i.e., a command that does not take geometric imperfections into account). In step 55, the control unit 16 collects information indicative of correction parameters in memory 16a, so that the modulator 3 can be controlled in an adjusted manner in step 56, in which a second display command function is executed.

[0088] In step 62, in which a pixel usage configuration is generated and which is functionally similar to step 52, the individualized modulator 3 is used to compensate for the geometric defects specifically identified in the calibration phase 50.

[0089] 5A and 6A illustrate the visible distortion effects that can affect the projection of horizontal boundaries or interruptions 35. Projected image F3 may contain brightness defects, for example, at the corners of projection screen E1 (a shift at the edge as shown in FIG. 6A). If optical module 1 has such geometric defects, e.g., for the segmented light beam in this example, the method can be implemented by rearranging the use of pixels 30 to reposition the boundary between activated and inactivated pixels forming emitted light R2. Here, in this non-limiting example, the number of pixels 30 is sufficiently large to accommodate a resolution of less than 1°, preferably about 0.1° or less. Additionally, the upper zone of modulator 3 may include an excess of pixels 30 relative to the initially specified pixel requirements to provide a margin needed for applying corrective effects.

[0090] To compensate for the distortion effect shown on the right side of FIG. 6A, the process shown in FIG. 4 or a similar process is applied, taking into account correction parameters. Indeed, here, for the corner zone of the digital micromirror device 6, the distribution of the ON pixels, which are provided to define the horizontal boundary at the height level A0 shown in FIG. 5A, is changed. The effect of converting the first display command to the second display command results in a completely different distribution of the pixels 30 for the same corner zone. This distribution is shown in FIG. 5B. Here, the separation at the height level A0 is replaced by a stepped profile, and the height levels of the activated pixels 30 gradually increase up to the maximum height level A1. The added column sections LP1, LP2, and LP3 can compensate for local brightness defects in the corner zone. Referring to FIG. 5B, the added peripheral zone Z1 results from the definition of the correction parameters obtained in the calibration phase 50. An example of this peripheral zone Z1 is given in the upper left corner of the example shown in FIG. 6A.

[0091] Naturally, other zones of the digital micromirror device 6 can be treated by subtracting pixels 30 to avoid excessive brightness. In particular, the control unit 16 corresponding to the optical module 1 can remove and add pixels 30, for example pixels forming columns or sections of columns of pixels LP1, LP2, LP3, or rows or sections of rows of pixels.

[0092] In particular, at each use of the optical module 1 in a motor vehicle, after the correction parameters have been implemented and taken into account, the image F3 projected on the screen E1 will better correspond to the desired image of the first display command F1. In the specific case in which the optical module 1 is used for lighting purposes (in particular for high beam or low beam), some pixels 30 can be neutralized or attenuated to ensure that they are subjected to deformations or distortions that do not cause dazzle to road users or only cause dazzle within legal limits.

[0093] The memory 16a can optionally store a default configuration state of the micromirrors 12, which can be changed to take into account the modification parameters. Such a change corresponds to a change in the display command. Of course, adjusting the distribution of activated and deactivated pixels by changing the display command can be implemented in many different ways.

[0094] Methods for correcting / compensating for geometric defects can be utilized to correct both defects related to centrality and deformation(s) due to distortion, as well as certain more localized anomalies if necessary.

[0095] One of the advantages of the optical module 1 is that it can project a light beam that may be uniform, so that the projection optical components 18 of the optical module 1 appear to be perfectly assembled, but in fact do not have to rely on cumbersome or overly expensive manufacturing and assembly modes.

[0096] It will be obvious to those skilled in the art that the present invention enables embodiments to take many other specific forms without departing from the field of application of the invention.

[0097] Thus, although optical module 1 has been described with reference to an example in which projection screen E1 is defined internally relative to a transparent wall forming the outer lens of transparent cover 14b, it will be appreciated that the projection screen may be defined by part of transparent cover 14b or another element forming part of outer housing 14. Projection optics 18 may be focused not on a separate screen, but, for example, on a film formed on the outside of the outer lens.

[0098] Furthermore, additional functions may be implemented as desired. For example, it will be appreciated that in the context of wide-angle imaging optics (numerical apertures of 0.5, 0.6, or 0.7, as non-limiting examples), indicia or marks may be added within the output beam 40. In particular, by using the high-resolution pixelated spatial modulator 3 and correcting anomalies, symbols (letters, numbers, or the like) may be formed with sufficient resolution so that messages or pictograms indicating, for example, the activation of a function or the operating status of the vehicle may be displayed to attract the attention of an outside observer.

Claims

1. A method for correcting geometric defects in a light beam projected by an optical module (1) of a motor vehicle, comprising: The optical module (1) comprises: an imaging device comprising a high-resolution pixelated spatial modulator (3) and a projection optics (18), said imaging device being suitable for projecting an output beam (40) having at least one horizontal boundary, said output beam (40) being defined by a plurality of pixels (30); a light source (2) for generating light directed towards said modulator (3); Including, The method comprises: - receiving a first display command (F1) for displaying an image to be projected, the first display command (F1) being directed to said modulator (3); - transforming said first display command (F1) into a second display command (F2) taking into account a correction parameter; The method comprises the steps of: the correction parameters are predetermined based on knowledge of geometric imperfections specific to the projection optics (18), whereby the modulator (3) is controlled in such a way that an image (F3) actually projected using the imaging device matches the image to be projected better than if the correction parameters were not taken into account; The method of claim 1, wherein the second display command (F2) differs from the first display command (F1) by selectively removing and adding sections (LP1, LP2, LP3) of one or more columns of pixels (30).

2. When compensating for luminance defects, the column sections (LP1, LP2, LP3) are added by the modulator (3) to a peripheral zone (Z1) of the horizontal boundary, The method of claim 1.

3. - a lateral shift of the profile of the light beam transmitted by the projection optics (18), and - deformation of the profile of the light beam transmitted by the projection optics (18), the correction parameters are adapted to modify the activation states of the pixels (30) defined by the modulators (3) so as to compensate for at least one defect of The method of claim 2.

4. the correction parameters are adapted to modify the duration or frequency of activation of the pixels (30) of the modulator (3) so as to compensate for a decrease in brightness of the projected image (F3) near the outer edges of the light beam transmitted by the projection optics (18); 4. The method according to any one of claims 2 to 3.

5. the modification parameters and / or the second display command (F2) are stored in a memory (16a) accessible to a control unit (16), the control unit (16) being adapted to activate the second display command (F2); 5. The method according to any one of claims 1 to 4.

6. A lighting system (5) for a motor vehicle, allowing the implementation of the method according to any one of claims 1 to 5, comprising: The system (5) an optical module (1), an imaging device comprising a high-resolution pixelated spatial modulator (3) and projection optics (18); a light source (2) for generating light directed towards said modulator (3); an optical module (1) comprising: a control unit (16) designed and arranged to control said modulator (3) and suitable for receiving a plurality of first display commands (F1), each of which indicates an image to be projected; Including, said control unit (16) comprising adjustment means (17) for converting each first display command (F1) into a second display command (F2) taking into account the correction parameter; The correction parameters are predetermined based on recognition of geometric defects specific to each projection optical component (18), and the control unit (16) controls the modulator (3) in response to second display commands (F2) so that an image (F3) actually projected using the imaging device better matches the image to be projected compared to when the correction parameters are not taken into account.

7. The high-resolution pixelated spatial modulator (3) comprises a digital micromirror device (6), the micromirrors (12) of the digital micromirror device (6) each having: a first position in which the micromirrors (12) are arranged to reflect a light beam (R1) from the light source (2) or from a light-emitting unit (20) including the light source (2) in the direction of the projection optics (18); a second position in which the micromirrors (12) are arranged to reflect the light rays (R1) from the light source (2) or from a light emitting unit (20) including the light source (2) away from the projection optics (18); It is movable between The system of claim 6.

8. the control unit (16) has access to a memory (16a) for storing information indicative of the modification parameters and / or the second display command (F2); The system of claim 7.

9. It comprises two optical modules (1), Each optical module (1) an imaging device comprising a high-resolution pixelated spatial modulator (3) and projection optics (18); a light source (2) for generating light directed towards said modulator (3); Including, Each light ray transmitted by one of the projection optics (18) is received at at least one projection screen (E1); the control unit (16) is adapted to control the modulator (3) of each of the two optical modules (1) and to take into account a first set of correction parameters corresponding to a first of the two optical modules (1) and a second set of correction parameters corresponding to a second of the two optical modules; the first set of correction parameters are predefined based on recognition of geometric imperfections specific to the projection optics (18) of the first optical module, while the second set of correction parameters are predefined based on recognition of geometric imperfections specific to the projection optics (18) of the second optical module. A system according to any one of claims 7 to 8.

10. A lamp for lighting and / or signaling a motor vehicle for projecting at least one light beam, comprising: - housing; - a closed outer lens; - a lighting system according to any one of claims 6 to 9, A lamp comprising:

11. A light emitting assembly having a first part and a second part, The first part and the second part are - two lamps, - two headlamps, or - lamps and headlamps, and The light emitting assembly comprises the system of claim 9 , The two optical modules (1) in the system are distributed such that one is located in the first component and the other is located in the second component. Light-emitting assembly.

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