Projection display

Abstract

The invention relates to a projection display comprising at least one light source (1) having at least one composite assembly (2) consisting of at least two individual optical channels (K), each of which is formed from a respective spatial light modulator (D), influencing the light propagation direction pixel by pixel, and an optical element (O), and it holds true for all the channels of the composite assembly that when light enters the composite assembly (2), the cross-channel totality of the optical elements of all the channels illuminates the spatial light modulator (D) in such a way that the optical element (O) of a channel in question images the light reflected at the spatial light modulator (D) as an object structure and all the image representations of the individual channels are superimposed to form one or more virtual or real total images on a screen (3).

Description

[0001] Projection display

[0002] The invention relates to a projection display comprising at least one light source and regularly arranged optical channels. In particular, the invention relates to digital projection systems based on reflective pixelated surface light modulators (digital micro-mirror devices, DMDs).

[0003] It is known that the projection of static and dynamic image content onto a screen is achieved using a slide projector or a projection display with one imaging channel or three imaging optical channels for color mixing, or by laser scanners. The miniaturization required for use, for example, as mobile imaging systems, regularly leads to a loss of brightness in the projected image.

[0004] Conceivable areas of application of the invention are therefore in the field of communication and entertainment electronics, data visualization, spectrometers, 3D printers and in the automotive sector, in particular for interior lighting and automotive exterior lighting, such as headlights.

[0005] Color-sequentially LED-illuminated picoprojectors are known from US 2006 / 0285078 A1, but their miniaturization is only possible to a limited extent due to the limitation of the transmittable luminous flux due to the small surface area. This relationship is determined by the fundamental optical law of etendue conservation. Real optics increase the etendue or reduce the system transmission. Thus, for a minimum transmittable luminous flux within a projecting optical system, a minimum required object area is also required. In single-channel projection systems, due to optical principles (natural vignetting, aberrations), the system length increases concurrently with this area to be imaged, making miniaturization difficult. The novel array projector approach presented here overcomes this dependence between projection brightness and system length.

[0006] Scanning laser projectors represent an alternative concept for the radical miniaturization of projection systems. As described in US Patent Application No. 20080265148, image content is generated by scanning a power-modulated laser beam across the image surface. The brightness achievable with this approach is primarily limited by the low power of available single-mode lasers and their limited modulation capability. Another significant disadvantage is speckle structures in the projected image, which limit the achievable resolution.

[0007] DE 102009024894 A1 relates to a projection display with at least one light source and regularly arranged optical channels. The optical channels contain at least one field lens, each of which is assigned an object structure to be imaged and at least one projection lens. The distance between the projection lenses and the assigned object structures corresponds to the focal length of the projection lenses, while the distance between the object structures to be imaged and the assigned field lens is selected such that Köhler illumination of the assigned projection lens is enabled. The individual projections are then superimposed to form the overall image.

[0008] From DE 102010030138 A1, a projection display (100) is known with at least one light source (110), at least one reflective image generator (120) which is designed to display individual images in a two-dimensional distribution (122) of partial areas (124) of the same, a projection optics arrangement (130) with a two-dimensional arrangement (132) of projection optics (134) which is configured to image an associated partial area (125) of the at least one image generator (120) onto an image plane (150) so that images of the individual images are superimposed in the image plane (150) to form an overall image (160), and at least one beam splitter (140) which is arranged in a beam path between the at least one reflective image generator (120) and the two-dimensional arrangement (132) of projection optics (134) on the one hand, and the beam path between the at least one light source (110) and the at least one reflective imager (120) on the other hand.

[0009] Another projection display with an image generator is described in DE 102011076083 A1, which is designed to generate individual images in a distribution, such as a two-dimensional distribution, of partial areas of an imaging plane of the image generator, and a multi-channel optics which is configured to image an associated individual image or an associated partial area of ​​the image generator per channel, in such a way that the image of the individual images is at least partially superimposed on a projection surface to form an overall image, wherein the projection surface is a non-planar free-form surface, such asa curved surface, and / or is tilted relative to the imaging plane, and the imager is configured such that constellations of points in the partial images, which are each superimposed by the multi-channel optics at a respective common point in the overall image, differ depending on the distance of the respective common point in the overall image from the multi-channel optics. Alternatively, the imager and multi-channel optics are configured such that a characteristic of a contribution of each channel to the overall image varies locally across the overall image depending on the distance of the respective common point in the overall image from the multi-channel optics.

[0010] According to the solution from DE 102013208625 A1, it is possible to generate images to be projected at different projection distances using a multi-aperture projection display, statically or without any adjustment - neither mechanical nor image generator-related - by suitably designing the individual images of the multi-aperture projection display, namely by combining preliminary individual images for the projection channels of the multi-aperture projection display, which are provided for each of the at least two images to be projected, projection channel by projection channel to form the actual or final individual images.

[0011] According to the current state of the art, digital projection systems use a spatial light modulator (SLM), which allows the light incident on it to be modulated in such a way that image information is generated and subsequently projected onto a screen by optical arrangements or, as in the case of laser-scanning systems, directly projected onto a screen. Each optical projection system is characterized by the luminous flux it can emit. The luminous flux of a single-channel projection system F EKP is directly proportional to the square of the focal length of its projection lens (given the slide area A, brightness of the light source B, system transmission T, f-number of the projection optics F and the paraxial focal length f MKP the projection optics):

[0012] Multi-channel projection systems modeled on DE 102009024894 A1 circumvent this dependency by using a two-dimensional arrangement of projection channels. The luminous flux of such multi-channel projector systems (FMKP) is calculated as follows: with N as the number of all channels in the array and f MKP as the paraxial focal length of a single channel of the array.

[0013] If you now compare a single-channel projector with a multi-channel projector with the same luminous flux, the relationship between the focal lengths is:

[0014] For example, a multi-channel projector with 100 or 10*10 projection channels requires only a tenth of the focal length of a single-channel projector to transmit the same luminous flux. This creates enormous space savings potential, as the overall length of a projector is directly correlated with its focal length.

[0015] The object of the invention is to propose a digital projection display that implements a previously unattainable combination of luminous intensity, compactness and efficiency with a minimal number of necessary components.

[0016] This problem is solved by the projection display having the features of claim 1. The further dependent claims show advantageous embodiments.

[0017] The present invention describes the technical solution for transferring the array projection principle to DMD (digital micro-mirror device) for modulating the light to be imaged.

[0018] This technology is often referred to as DLP (brand name of Texas Instruments).

[0019] DMDs modulate the incoming light through controlled deflection using a two-dimensional matrix array of reflective pixel surfaces, which can individually switch their tilt angle between two states in a bistable manner with high frequency through electrical control. These two defined states are referred to as ON and OFF.

[0020] If the light striking the DMD and subsequently reflected by the micromirrors passes through the projection lens assigned to the DMD in the direction of the screen and is optically imaged by the optical refractive power of the projection lens, this is referred to as the ON state of those pixelated tilting mirror surfaces.

[0021] In the OFF tilt mirror state, light beams are not directed toward the associated projection lens, but are typically directed to a beam trap. This means they are not used for the projection image and do not reach the screen. Pixels of a DMD in the flat state deflect the light uncontrollably into an intermediate angular range between the ON and OFF deflection directions, typically also into a beam trap. [https: / / www.ti.com]

[0022] The advantages of a DMD over other surface light modulator technologies such as LCD or LCoS lie in its inherently high transmission due to reflection instead of absorption, its modulation capability even when using unpolarized light, and the ability to modulate light across a wide spectral range from UV to VIS to IR. According to the current state of the art, DMDs with pixels of only 5.4 x 10' are possible. 6m distance from each other and a total pixel count of 1920x1080 pixels.

[0023] The solution according to the invention will be explained in more detail below using exemplary embodiments and figures 1 to 19.

[0024] Figure 1 shows an example of a y-sectional view of the projection display according to the invention, which produces a real overall image on a screen 3.

[0025] The light emitted by a light source 1 strikes a composite 2, consisting of optical channels K, formed in a two-dimensional ixj matrix lying in the xy-plane with i ∈ {1,2, 3, 4, 5, 6} and j ∈ {1,2,3}, consisting of individual optical channels with center distances p oi in x-direction and p oj in the y-direction to each other as their matrix elements K i,j , each defined by:

[0026] K i,j = (D i , ,j , O i,j) with i,j ∈ N and j ∈ {1,2,3} and i ∈ {1,2, 3, 4, 5} K i,j = (O i,j} with i,j ∈ N and j ∈ {1,2,3} and i = 6 with a surface light modulator D that can address the light propagation direction pixel by pixel by reflection i,j , whose normal vector of light incidence and light exit vector runs parallel to the y-axis after reflection, arranged in 5-rows and jmax-columns, and an optical element O i,j , arranged in 6 lines and j max -columns, where the respective optical single channel K i,j is designed in such a way that when light enters the composite 2, the surface light modulators D i,j of the single channel K i,j the i-th row and the j-th column of a subset determined by the lighting assignment function b(i,j) according to or defined identical optical elements (O i,j), with a counting method for i in which the (i+1)-th channel row is always positioned between the i-th channel row and the light source. Channel rows have a decreasing distance to the light source 1 with increasing row index i, so that after reflection at the area light modulator D i,j the i-th row and j-th column of each of the area light modulators Dq from the set determined by the projection assignment function p(i,j) according to

[0027] = {O i,j} defined optical elements O i,j The i-th row and j-th column are optically imaged, and all individual projection images of the composite 2 are superimposed to form one or more virtual or real overall images on a screen 3. Individual channels with the same i-index are referred to below as rows, and channels with the same j-index are referred to below as columns. The counting of i and j is ascending in the positive x- and y-direction, starting with index 1.

[0028] A surface light emitter of the channel of the i-th row and j-th column is therefore illuminated by a combination of itself and its channel row neighbors located in the direction of the light source, which is permissible according to the above subset description b(i,j), and after reflection at the surface light modulator is imaged or projected by its optical element assigned in the same channel.

[0029] The optical elements O 6,j have no projecting function in the exemplary arrangement, but only serve to illuminate the last row of surface light modulators D 5,j of the array. The channels K 6,j are therefore a special case and, in contrast to all other channels, do not have a dual function as lighting and projection channels, but are therefore merely lighting channels.

[0030] In the flat state of a mirror pixel of the area light modulator, the mirror surfaces are oriented in a plane parallel to the xy plane. To achieve the on state of all pixels of the individual area light modulators Di,j, they are rotated around an axis formed by their surface center and the y-unit vector of the system by the angle α. DMD in such a way that the normal vector of the reflecting pixel surfaces, which pointed in the direction of the z-axis in the FLAT state, is now tilted in the direction of the light source.

[0031] All optical elements O i,j are identical to each other in the exemplary arrangement shown. Adjacent channels in the x-direction are designated O i,j and O (i+1)j The (i+l)j-th optical element O (i+1)j is designed in such a way that the light beam reaching it from the light source 1, the i,j-th surface light modulator D i,j illuminated and the optical element Oi,j , which is identical to the optical element of its neighboring channel O i+1,j is designed to incorporate the area light modulator D i,j to a real single image on a screen, and the totality of the individual images of all individual channels K i,j to form an overall image on a screen 3 at a distance L1.

[0032] For long projection distances, the distance of the optical element O i,j in z-direction to its corresponding area light modulator D i,j according to the imaging equation of geometric optics approximately the paraxial focal length f MKP of the optical element of the individual projection channel. Shown are the principal rays of the light beams responsible for the image.

[0033] The system is designed in such a way that only light beams from the i-th channel K i,j respective (i+1)-th adjacent channel K i+1,jthe area light modulator D i,j , ie in the i-th channel row, in such a way that the reflected light reaches the optical element O corresponding to this area light modulator with row index i i,j can effectively pass through as a projection lens and is focused onto a screen. For optimal telecentric illumination of the i-th optical element, the angle of incidence of the main ray of the light beam, which is incident on the center of the area light modulator D i,j , coming from the (i+1)-th optical element, preferably meets twice the maximum deflection angle of the tilting mirror α dmd .(see Figure 14)

[0034] The optical axes of the individual projections of all individual channels K i,j have a defined center-to-center distance difference between adjacent optical elements p Oi and p ojand adjacent surface light modulators pdi and pdj converge to each other, which ensures that all individual images on a screen 3 completely overlap to form an overall image at a distance L1. The following applies:

[0035] Figure 2 shows the arrangement from Fig.1 and instead of the main rays the full light beams for the lowest pixel of the overall image in the x-direction.

[0036] Figure 3 shows the arrangement from Fig. 1 and instead of the main rays the full light beams for the center of the overall image in the x-direction.

[0037] Figure 4 shows the arrangement from Fig.1 and instead of the main rays the full light beams for the topmost pixel of the overall image in the x-direction.

[0038] Figure 5 shows the arrangement from Fig. 1. Instead of the ON state of all individual pixels of the area light modulator (as shown in Figs. 1-4), the normal vectors of the individual mirrors are now oriented along the z-axis. In DMDs, this is commonly referred to as the FLAT state. In this pixel state, the arrangement ensures that the light beams striking the reflective area light modulators are not imaged onto the screen 3 and land in a beam trap 12.

[0039] Figure 6 shows the arrangement from Fig.1, where instead of the previous orientation of the tilting mirrors in the ON state (Fig.1-4) the individual mirror surfaces are now tilted by the angle 2α DMDrotates clockwise from the light source around the axis defined by the pixel area center and the system's y-unit vector. This designates the off state of the individual pixels of the area light source. All light beams hitting off pixels are deflected downwards even more than in the flat state (see Fig. 5) and do not contribute to the image on the screen. To minimize stray light, they are directed into a beam trap 12.

[0040] Figure 7 shows the arrangement according to the invention according to Figure 1 with five individual projections without convergence to each other. The individual channel projections are only combined with the aid of a biconvex lens 4 (converging lens) with a fixed positive focal length F Makro at a distance F Makro to form an overall image on screen 3 and combined by complete superposition.

[0041] Figure 8 shows the inventive arrangement according to Figure 1 with individual projection images which leave the composite 2 without convergence, i.e. parallel to one another. The individual projection images strike an overall lens 5 with a variably adjustable focal length. This aligns the optical axes of the individual projections depending on their set focal length (a negative focal length is shown in the image), so that the individual projection images can be aligned convergently, parallel to one another, or divergently to one another in the direction of a screen 3. This adjustable focal length enables variable image synthesis, in order to be able to dynamically switch between different overall images with maximum luminance and a minimum number of images and a minimum image size, or an overall image with a maximum number of pixels and minimum luminance and a maximum image size.

[0042] Figure 9 shows the arrangement according to the invention implemented by combining the single surface light modulators D i,j in the form of a large-area composite area light modulator 6. The individual optical elements are designed as a monolithic component in the form of a lens array 7, each consisting of two optical surfaces per individual channel. The optical surface facing the area light modulator 6 is a freeform surface, and the surface facing the screen is an aspherical surface. The effective light beams are shown both in the illumination beam path 13 and in the projection beam path 14 (after reflection at the DMD) for three different pixels. The light illuminating the i-th area light modulator comes entirely from the directly adjacent channel in the y-direction with line index i+1.

[0043] Figure 10 shows a concrete embodiment of the invention. This is an array of surface light modulators Dq with 5 rows and j columns, equipped with a cover plate 8 positioned in front of them in the projection direction. The optical elements O i,j The individual channels, arranged in 6 rows and j columns, are formed by two lenses each, each with two optical surfaces. The optical assembly 9 is formed by two double-sided monolithic lens arrays, with the first lens array 9a being a two-dimensional arrangement of the first lens made of the optical element O i,j and the second lens array 9b is a two-dimensional arrangement of the second lens from the optical element O i,j contains.

[0044] The illumination of the area light modulator D i,j is carried out by both the optical element O (i+1)j as well as O (i+2)j . The projection of the area light modulator D i,jis carried out by the optical element O i,j for each channel row with i ∈ {1, ... ,5}. The principal ray paths for the projections from the channel rows with i ∈ {1,3,5} are shown.

[0045] Figure 11 shows the arrangement according to the invention, in which the separation of the illumination beam path 13 and the projection beam path 14 of the individual channels is carried out using a monolithic prism 10. The light beams coming from the light source 1 of the illumination are totally reflected on a side surface of the prism 10 due to their flat angle of incidence (TIR prism) and then reach the composite 2 under oblique incidence. Due to the reflective deflection and angle change of the light beams at the surface light modulators D i,j , each light beam passing through the respective optical element O i,jto form a single projection image, are transmitted toward the screen 3 through the prism 10 and through a second prism 11, which compensates for the refractive angular deflection of the prism 10. This allows for an even more compact design compared to the arrangement in Figure 1, since the beam paths, even if they are not yet spatially separated from one another, can be directed by total internal reflection, i.e., in different directions depending on the angle, and are thus spatially separated within a minimal installation space. All individual projection images are completely superimposed to form an overall image on the screen 3.

[0046] Figure 12 shows the invention, where, in contrast to Figure 11, the beams of the illumination pass through a prism 10 refractively and reach the compound 2 without total reflection. Due to the reflective angular deflection at the surface light modulators D i,j and subsequent imaging by the optical elements Oi,j The light beams in the projection beam path are totally reflected at a boundary surface of prism 10 and thus deflected toward the screen. As in Fig. 11, the use of total reflection as an angle filter enables a further reduction in the size of the overall system compared to the arrangement in Fig. 1.

[0047] Figure 13 shows the invention in two different states. State 1 corresponds to a projection of a real overall image at projection distance L1 from compound 2, and state 2 (dashed lines) shows the projection of a real overall image at a second projection distance L2, where L1 <L2. Die Vergrößerung der Projektionsentfernung ergibt sich aus einer verringerten Konvergenz der Einzelprojektionsbilder zueinander, welche durch verringerten Mittenabstand benachbarter Einzelflächenlicht- modulatoren erzeugt wird. Aufgrund der elektrischen Ansteuerbarkeit der Bildinhalte der Einzelflächenlichtmodulatoren kann vorzugsweise ohne mechanische Verschiebung der D i,j itself, but only by shifting the image information to the D i,j relative to each other, an effective change in the PDI can be realized and thus different distances can be generated for the synthesis of an overall image.

[0048] Figure 14 shows the invention as an example using a combination of 3 channels consisting of K 1,j =(D 1,j , O 1, j ) and K 2,j =(D 2,j ,O 2,j ) and K 3,j =(O 3,j ). The angle of incidence of the main beam on the area light modulator is 2α DMD at a tilt angle of α DMD to create a telecentric illumination of the optical element.

[0049] Figure 15 shows the inventive arrangement from Figure 1, supplemented by a reflector 15 in the illumination beam path. This serves to further miniaturize the arrangement.

[0050] Figure 16 shows a concrete embodiment of the invention. It is an arrangement of surface light modulators D i,j with 5 rows and 3 columns. The optical elements O i,jThe individual channels, arranged in 6 rows and 3 columns, are formed by two lenses each, each with two optical surfaces. The optical composite 16 is formed by two double-sided monolithic lens arrays, with the first lens array 16a being a two-dimensional arrangement of the first lens made of the optical element O i,j and the second lens array 16b is a two-dimensional arrangement of the second lens from the optical element O i,j contains.

[0051] The illumination of the single area light modulator D i,j In contrast to Fig. 10, this is done by the optical element O i,j as well as O (i+1)j ie, the direct neighbor and a subset of the optical elements of its own channel. There is no cover plate 8 in this arrangement. The projection of the area light modulator D i,j is carried out by the optical element O i,jfor each channel row with i ∈ {1,2, 3, 4, 5}. The principal ray paths for the projections from the channel rows with i ∈ {1,3,5} are shown.

[0052] Figure 16a shows the spatial and angular distribution of light source 1 from the arrangement in Fig. 16. The light source has a rectangular shape with a larger extension in the x-direction and a quadratic angular distribution with divergence angles of approximately ±5° in the x- and y-direction.

[0053] Figure 16b shows the spatial and angular distribution recorded in the plane of the screen-facing entrance surfaces of the optical elements O i,j The light from the light source hits at a chief ray angle of approximately -24°, which is twice the tilting mirror angle of the DMD α DMD corresponds to the optical elements O i,j with i ∈ {2, 3, 4, 5, 6} and j ∈ {1,2,3}.

[0054] Figure 16c shows the spatial and angular distribution recorded in the plane of the area light modulators D i,j Each of the 5x3 illuminated optical elements generates an image of the angular distribution of the light source on the DMDs channel by channel. The main ray angle of the light beams for the image center is +24° in the x-direction. Tilting mirrors in the ON state direct this main ray angle to 0°, i.e., in the z-direction, through the D i,j The corresponding optical element deflects the main beam angle to the screen direction. Tilting mirrors in the flat state deflect the main beam angle to x-24°, and pixels in the off state deflect the main beam to -48°.

[0055] Figure 16d shows the arrangement from Fig. 16 in 3D. It shows the beam path of three main rays coming from light source 1 for imaging the centers of the area light modulators D. 3jwith j ∈ {1,2,3}. The following beam paths are shown as examples:

[0056] O 41 illuminated D 31 and is from O 31 projected in the direction of the screen.

[0057] O 42 illuminated D 32 and is from O 32 projected in the direction of the screen.

[0058] O 43 illuminated D 33 and is from O 33 projected in the direction of the screen.

[0059] Figure 17 shows, in a special embodiment of the inventive solution, the combination of two projection displays PD according to the invention a and PD b , PD a consisting of the light source la and the compound 2a, and PDb consisting of the light source lb and the compound 2b.

[0060] The light source la is designed in such a way that only the half of each surface light modulator D that is further away from the light source in x-orientation a1,j(shown as an example for the area light modulator D a1,j with the lower half of the picture 18 a1,j ) is illuminated. The projection display PDb corresponds to the projection display PD a , mirrored at the center of the area light modulators D a1, v j shifted yz-plane. All pixels of all surface light modulators are initially in the FLAT state. All surface light modulators of the projection display PD a are controlled by the projection display PDb, as well as the optical elements of the lines O a1,j with i ∈ {1,2, 3, 4, 5}. Therefore, the designation of the optical elements O a1,j ≡ O b5,j and O a2,j ≡ O b4,j and O a3 ,j ≡ O b3,j and O a4,j ≡ O b2,j and O a5,j ≡ O b1,j and for the area light modulators D a1,j ≡ D b ,j and D a2,j ≡ D b4,j and D a3,j ≡ D b3,j and D a4,j ≡ D b2,jand D a ,j ≡ D b1,j .

[0061] If you now invert the image content of the channel-specific upper half of the image 17 a1,j (shown as an example with 17 a1,j for the channel (K a1,j )) of all surface light modulators, these image contents affect the projection displays PD b or when the light source lb is irradiated onto 2b as if the pixels of the upper halves of the area light modulators were not inverted and are accordingly illuminated by the optical elements O a1,j with i ∈ {1, ... ,5} towards screen 3. The combination of all channels can thus project an overall image with the correct distribution of illuminated and unilluminated areas through the interaction of all optical elements and both light sources with correct modulation of the tilting mirror states.

[0062] The advantage of this arrangement of two combined projection displays PD aand PDb are the lower technical requirements for the optical elements of each channel, as they must now illuminate a significantly smaller area of ​​each adjacent channel or be able to image it internally within the channel. To avoid stray light in the projection image, it is advantageous to ensure the sharpest possible separation and a clean connection of the illumination areas on the area light modulators between the illumination areas coming from la and lb.

[0063] Figure 17a shows the arrangement from Figure 17 in the z-view, illuminated by the light source la. All 5x3 area light modulators are shown, each illuminated only in its lower half by la. The area elements acting as ON pixels for the light source la are hatched, while the area elements acting as OFF pixels are shown in black.

[0064] Figure 17b shows the arrangement from Figure 17 in the z-view, illuminated by light source 1b. All 5x3 area light modulators are shown, each illuminated only in its upper half by 1b. The area elements acting as ON pixels for light source 1b are hatched, while the area elements acting as OFF pixels are shown in black.

[0065] Figure 17c shows the merged projection image of all images of all lower halves of image 18 ai,j by PD a and all images of all upper halves of the image 17 ai,j by PDb on screen 3, consisting of a dark "F" in the center of a brightly illuminated square.

[0066] Figure 18 shows the exemplary superposition of two individual projection images on screen 3, where these are shifted in the x-direction and y-direction by P / 2, with P being the center-to-center distance of the projected pixels of a surface light modulator Dq of a network 2. This allows a doubling of the displayable modulatable image pixel count in both the x-direction and y-orientation, i.e., a quadrupling of the total displayable pixels.

[0067] Each image shows 2x2 projection pixels from the total number of all projection pixels of a single projection image, usually consisting of several hundred pixels in x- and y-orientation. This form of half-pixel overlay can be generated by adjusting the spatial offset of a subset of the individual projectors. This can be achieved, for example, by decentering a subset of all optical elements relative to a second subset of all optical elements. This effect, commonly called lens shift, by a half-pixel extension on the image side in x- and y-orientation, can be realized both by decentering a subset of optical elements and by decentering a subset of area light modulators with respect to a regularly arranged array of optical elements with the same center-to-center spacing.In contrast to conventional single-channel projection systems, which usually use high-frequency mechanics to realize this half-pixel superposition in a time-sequential manner, a multi-channel projection system designed in this way can generate an increase in the displayable image information (superresolution) without moving parts (solid-state).

[0068] Figure 19 shows the exemplary superposition of three individual projection images on screen 3, where these are shifted in the x-direction and y-direction by P / 3, with P being the center-to-center distance of the projected pixels of a surface light modulator Dq of a network 2. This allows a tripling of the displayable modulatable image pixel count in both the x-direction and y-orientation, i.e., a ninefold increase in the total displayable pixels (superresolution). In contrast to Fig. 18, this requires three subsets of channels K. i,jwhose optical axes are deflected either by a 1 / 3 pixel shift or a 2 / 3 pixel shift in angular space to a first subset of optical channels. Deflection can be achieved, for example, by decentering a subset of all optical elements with respect to the entire set of area light modulators with a uniform center-to-center distance, or by decentering a subset of area light modulators with respect to the entire set of optical elements with the same center-to-center distance.

[0069] In a particular embodiment of the solution according to the invention, the paraxial focal length of the optically active elements is preferably 0.5 mm - 30 mm.

[0070] It is advantageous in the solution according to the invention that due to the superposition of a plurality of surface light modulators provided with a channel-individual spatial illumination distribution on the screen 3, not only is the image information superimposed on the screen, but also all channel-individual spatial illumination distributions are superimposed on the D i,j on screen 3. This inherent arrangement-related mixing of the light distributions ensures better uniformity of the light distribution across the entire image compared to conventional single-channel projection systems.

[0071] A conventional single-channel projection system, which requires a comparable homogeneity of illumination of the overall image, therefore always requires a higher expenditure, e.g. due to a higher number of optical elements in the structure within the illumination beam path.

[0072] Due to the approximately significantly reduced focal length required for the projection system compared to a conventional projection system with the same luminous flux (depending on the number of channels N), Imaging requires optical elements, a significant space saving potential results from the use of the proposed multi-channel projection principle using the described reflective area light modulators.

[0073] The dual function of the optical elements in each channel—i.e., their use for both illumination and projection—results in enormous component savings compared to conventional projection systems. Due to the resulting lower complexity and reduced tolerance chain, this can lead to significantly more powerful, less susceptible to failure, and more cost-effective projection systems.

[0074] The application of the method described in DE 102011076083 A1 to the proposed inventive solution enables the projection of high-contrast, bright projection images on, for example, steeply inclined screen surfaces or freeform surfaces. In addition to the multi-channel arrangement, this is based on the utilization of the hyperfocality of each individual channel, resulting from the comparatively small optical aperture dimensions (0.5 mm to 10 mm) compared to conventional projection distances (10 cm to 10 m).

[0075] The application of the algorithms for object structure generation described in DE 102013208625 A1 can provide an extended depth of field compared to single-channel projection systems with the same luminous flux. In special cases, the calculation rules disclosed in DE 102013208625 A1 can also be used to generate more than one projection image within the 3-dimensional projection light field without requiring readjustment of the D i,j requires trained object information.

[0076] Using area light modulators D i,jWith a pixel brightness depth (number of gray levels) that can be controlled, for example, by 8-bit pulse width modulation, a displayable bit depth (number of displayable gray levels) of an image pixel of 256 x N results in a channel number of i • j ≡ N channels in the overall image 3. This corresponds to an increase in the displayable gray levels or image depth due to the multi-channel superposition projection principle.

[0077] The exemplary design, shown in Fig.9 and Fig.16, enables the use of the optical elements as a monolithic component to encapsulate the area light generator and replaces the cover plate required for conventional projectors.

[0078] In a further special embodiment of the solution according to the invention, it is proposed that within the network 2 a subset of projection channels K i,jwith the same column index j, channel-specific color filters with the same transmission spectrum, for example red, green or blue, are assigned and the corresponding area light modulators D i,j display the corresponding color component as ON pixels and thus create a full-color overall image on the screen 3 by superimposing all channels K colored in the primary colors i,j results.

[0079] The application of the arrangement described in DE 102012205165 B4 and DE 2013206604 A1 in combination with the arrangement according to the invention disclosed here enables the projection of virtual image contents, for example in the form of near-eye data glasses or an arrangement for reflecting information into the field of vision of a motor vehicle occupant.

[0080] The aspect ratio of commercially available DMD area light modulators is often 16:9. For the realization of an efficient projection system, it is advantageous to use optical elements with apertures whose ratio also corresponds to 16:9 or 1:1 due to the resulting optimal utilization of the area of ​​the area light modulators in combination with the usual spatial distributions of available light sources (high-performance LEDs, laser diodes).

[0081] One possibility for further increasing the system efficiency of the arrangement according to claim 1 is to feed light, which hits tilting mirror pixels of the area light modulators in the OFF state and leaves the assembly of optical elements unimaged after reflection at the area light modulator, without being able to hit the screen, into the illumination beam path a second or further time with the aid of further optical components, so that these can pass through the illumination beam path further times and thus possibly hit ON pixels on a further pass and can be imaged towards the screen.

Claims

Patent claims Claim 1: Projection display, with at least one light source (1), characterized in that it has at least one a system (2) comprising at least two individual optical channels (K), each of which is formed from an area light modulator (D) that influences the direction of light propagation pixel by pixel, and an optical element (O), and such that for all channels of the system, the inter-channel assembly of optical elements of all channels, upon light entering the system (2), illuminates the area light modulator (D) in such a way that the optical element (O) of this channel illuminates the area light modulator (D) at the The area light modulator (D) maps reflected light as an object structure and all images of the individual channels are superimposed to form one or more virtual or real overall images on a screen (3). Claim 2: Projection display according to claim 1, characterized in that a composite (2) consisting of individual optical channels K i,j , formed in a two-dimensional ixj matrix lying in the xy-plane with o ≥ 3 and j max ≥ 1 , consisting of individual optical channels as their matrix elements ( K i,j ), each defined by: with one that alters the direction of light propagation by reflection or a combination of reflection and Diffraction pixel-wise addressable area light modulator (Di, j), whose normal vector of The light incidence and light emission vectors run parallel to the y-axis, arranged in d-rows with d > 2 and jmax columns, and an optical element (O i,j), arranged in o-rows and jmax columns, wherein the respective optical single channel (Kij) is designed such that, upon light entering the assembly (2), the area light modulators (Dij) of the single channel (Kij) of the i-th row and the j-th column are selected from a subset defined by the illumination assignment function b(i,j) according to or defined optical elements (O i,j ) are illuminated, with a counting method for i, in which the (i+l)-th The channel row is always positioned between the i-th channel row and the light source. so that after reflection at the area light modulator (D i,j ) of the i-th row and j-th column of each of the (D i,j ) this from the set, which is defined by the projection assignment function p(i,j) according to p(i,j) = {O i,j} defined optical elements (O i,j) the i-th row and j-th column is optically mapped and all individual projection images of the composite (2) are superimposed to form one or more virtual or real composite images on a screen 3. Claim 3: Projection display according to claim 1 or 2, characterized in that the illumination beam path (17) of all individual channels is deflected at a reflector (19) arranged between the light source (1) and the assembly (2). Claim 4: Projection display according to claim 1 or 2, characterized in that a spatial separation of the illumination beam path (13) and the projection beam path (14) is achieved by total internal reflection within a prism (10) which is arranged between the light source (1) and the assembly (2), such that either the illumination beam path (13) is totally reflected and the projection beam path (14) is transmitted in the direction of the screen (3) or the illumination beam path (13) is transmitted in the direction of the assembly (2) and the projection beam path (14) is totally reflected in the direction of the screen (3). Claim 5: Projection display according to claim 1 or 2, characterized in that a total lens with variably adjustable focal length (5) is arranged between assembly (2) and screen (3), by means of which the optical axes of the individual image projections are aligned according to the set focal length, and thus a variable image synthesis, for example a total image with maximum luminance, minimum number of pixels and minimum image size, or a total image with minimum luminance, maximum number of pixels and maximum image size, can be dynamically realized. Claim 6: Projection display according to claim 1 or 2, characterized in that within the assembly (2), projection channels (K) i,j ) with identical j-index color filters with the same transmission spectrum, for example red, green or blue, and the corresponding area light modulators (D i,j) represent the corresponding color component as ON pixels and create a full-color overall image on the screen (3) by superimposing all channels colored in the primary colors (K i,j ). Claim 7: Projection display according to claim 1 or 2, characterized in that a subset of all projection channels (K i,j ) is designed in such a way that their corresponding overall projection image has a spatial offset in the plane of the screen compared to the projected overall image of a further subset of projection channels, which corresponds to a fraction of the pixel center distance of the projected area light modulator pixels and, through channel-individual modulation of the pixel information of all area light modulators, the superposition of all projections generates an integral overall image with an effectively representable number of pixels that is increased compared to the representable number of pixels of a single projection image.

Images