Projection display

Abstract

Projection display comprising at least one light source (1) and at least one assembly (2) consisting of 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 in that for all channels of the assembly the cross-channel totality of optical elements of all channels, upon light entering the assembly (2), illuminates the area light modulator (D) in such a way that the optical element (O) of this channel maps the light reflected at the area light modulator (D) as an object structure, characterized by that the assembly (2) consisting of individual optical channels K i,j , formed in a two-dimensional i × j matrix lying in the xy-plane with o ≥ 3 and j max ≥ 1, consisting of individual optical channels as their matrix elements (Ki,j ), each defined by: K i , j = ( D i , j , O i , j ) miti , j ∈ ℕ andj ∈ { 1, … , jmax} andi ∈ { 1, … , d} K i , j = ( O i , j ) miti , j ∈ ℕ andj ∈ { 1, … , jmax} andi ∈ ( d + 1, … , o ) undo ≥ d + 1 with a surface light modulator (D) that can address the direction of light propagation pixel by pixel by reflection or a combination of reflection and diffraction i,j ), whose normal vector of the incident and emitted light vectors runs parallel to the y-axis, arranged in d-rows with d ≥ 2 and j max -columns, and an optical element (O i,j ), arranged in o-rows and j max -columns, where the respective optical single channel (K i,j ) is designed in this way, so that when light enters the assembly (2) the area light modulators (D i,j ) of the single channel (K i,j) the i-th row and the j-th column of a subset defined by the lighting assignment function b(i,j) according to b ( i , j ) ⊂ { O i , j , O ( i + 1 ) , j , O ( i + 2 ) , j} with b ( i , j ) ≠ { O i , j} and b ( i , j ) ≠ ∅ or b ( i , j ) = { { O i , j , O ( i + 1 ) , j} , { O i , j , O ( i + 2 ) , j} , { O i , j , O ( i + 1 ) , j , O ( i + 2 ) , j} , { O ( i + 1 ) , j} , { O ( i + 1 ) , j , O ( i + 2 ) , j} , { O ( i + 2 ) , j}} defined optical elements (O i,j ) are illuminated, 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, 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 that 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 overall images on a screen 3.

Description

[0001] The invention relates to a projection display with at least one light source and regularly arranged optical channels. Specifically, the invention relates to digital projection systems based on reflective pixelated area light modulators (digital micro-mirror devices, DMDs).

[0002] 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 or three optical channels for color mixing, or by laser scanners. The miniaturization required for use, for example, as mobile image-generating systems regularly leads to a loss of brightness in the projected image.

[0003] Possible applications of the invention are therefore in the field of communication and consumer electronics, data visualization, spectrometers, 3D printers and in the automotive sector, in particular for interior lighting and automotive exterior lighting, such as headlights.

[0004] Color-sequential LED-illuminated picoprojectors are known from US patent 2006 / 0285078 A1, but their miniaturization is limited due to the small surface area restricting the transmittable luminous flux. This relationship is governed by the fundamental optical law of conservation of étendue. Real optics increase the étendue or decrease the system transmission. Thus, a minimum required object area is necessary for a minimum transmittable luminous flux within a projecting optical system. In single-channel projection systems, due to optical principles (natural vignetting, aberrations), the system length increases proportionally with the projected area, making miniaturization difficult. The presented novel approach of the array projector overcomes this dependency between projection brightness and system length.

[0005] Scanning laser projectors represent an alternative concept for the radical miniaturization of projection systems. As described in US 2008 / 0265148 A1, an image is generated by scanning a power-modulated laser beam across the screen. The brightness achievable with this approach is primarily limited by the low power of available single-mode lasers and / or their restricted modulation capabilities. Another significant disadvantage is the speckle patterns in the projected image, which limit the achievable resolution.

[0006] German patent 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, to which an object structure to be projected and at least one projection lens are assigned. The distance of the projection lenses to the assigned object structures corresponds to the focal length of the projection lenses, while the distance of the object structures to be projected to the assigned field lens is chosen such that Köhler illumination of the assigned projection lens is enabled. This results in the individual projections being superimposed to form the overall image.

[0007] A projection display (100) is known from DE 102010030138 A1, comprising at least one light source (110), at least one reflective image transmitter (120) configured to display individual images in a two-dimensional distribution (122) of sub-areas (124) of the same, a projection optics arrangement (130) with a two-dimensional arrangement (132) of projection optics (134) configured to map an associated sub-area (125) of the at least one image transmitter (120) onto an image plane (150) so that images of the individual images in the image plane (150) superimpose to form a total image (160), and at least one beam splitter (140) in a beam path between the at least one reflective image transmitter (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 (134) on the other. (110) and the at least one reflective image sensor (120) on the other side.

[0008] Another projection display with an image sensor is described in DE 102011076083 A1, which is configured to generate individual images in a distribution, such as a two-dimensional distribution, of sub-areas of an imaging plane of the image sensor, and a multi-channel optic configured to image an associated individual image or an associated sub-area of ​​the image sensor per channel, such that the image of the individual images in a projection surface at least partially overlaps to form a complete image, wherein the projection surface is a non-planar freeform surface, such as aa curved surface, and / or tilted relative to the imaging plane, and the image sensor is designed such that constellations of points in the partial images, which are superimposed by the multichannel 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 multichannel optics. Alternatively, the image sensor and multichannel optics are designed such that the contribution of each channel to the overall image varies spatially across the overall image depending on the distance of the respective common point in the overall image from the multichannel optics.

[0009] According to the solution from DE 102013208625 A1, it is possible to generate images to be projected with a multi-aperture projection display at different projection distances, statically or without any adjustment - neither mechanical nor image sensor-related - by appropriately 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, into the actual or final individual images, one projection channel at a time.

[0010] According to the current state of the art, digital projection systems use a spatial light modulator (SLM), which makes it possible to modulate the light hitting it in such a way that pictorial information is generated and subsequently displayed by optical arrangements or directed directly onto a screen, as in the case of laser scanning systems.

[0011] Every 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 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). EKP (projection optics): ΦEKP=πABT4F2∝fEKP2F4

[0012] Multi-channel projection systems based on the model of DE 102009024894 A1 circumvent this dependency by using a two-dimensional arrangement of projection channels. The luminous flux of such multi-channel projector systems F MKP This results according to: ΦMKP=πABT4F2∝fMKP2F4⋅N 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] Comparing a single-channel projector with a multi-channel projector of the same luminous flux, the following relationship between the focal lengths results: fMKP=fEKPN

[0014] A multi-channel projector with, for example, 100 or 10x10 projection channels requires only one-tenth the focal length of a single-channel projector to transmit the same luminous flux. This creates enormous potential for space savings, since the length of a projector is directly correlated with its focal length.

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

[0016] This problem is solved by the projection display with the features of claim 1. The further dependent claims describe 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 also referred to as DLP (a brand name of Texas Instruments). DMDs modulate incoming light by controlled deflection using a two-dimensional matrix arrangement of reflective pixel surfaces. These pixels can individually and bistablely switch their tilt angle between two states at high frequency through electrical control. These two defined states are subsequently referred to as ON and OFF.

[0019] When the light striking the DMD and subsequently reflected by the micromirrors passes through the projection lens associated with the DMD towards 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.

[0020] In the OFF tilting mirror state, light beams are not directed towards the associated projection lens, but are typically directed into a beam trap. This means they do not contribute to 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.

[0021] The advantages of a DMD over other area light modulator technologies such as LCD or LCoS lie in its inherently high transmission due to reflection rather than absorption, its modulation capability even when using unpolarized light, and the ability to modulate light across a wide spectral range from UV through VIS to IR. According to the current state of the art, DMDs with pixels as small as 5.4 x 10⁻⁶ are possible. -6 Available commercially with a spacing of m between each other and a total pixel count of 1920x1080 pixels.

[0022] The solution according to the invention will now be explained using exemplary embodiments and based on the Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. , Fig. until Fig. will be explained in more detail.

[0023] This shows Fig. The projection display according to the invention, which generates a real overall image on a screen 3, is shown by way of example in y-section view.

[0024] The light emitted by a light source 1 strikes a system 2 consisting of optical channels K, formed in a two-dimensional i × j 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 the x-direction and p Ojin the y-direction to each other as their matrix elements K i,j , each defined by: Ki,j=(Di,j,Oi,j)with i,j∈ℕ and j∈{1,2,3}and i∈{1,2,3,4,5} Ki,j=(Oi,j) with i,j∈ℕ and j∈{1,2,3} and i=6 with a surface light modulator D whose light propagation direction can be addressed pixel by pixel by reflection i,j , whose normal vector of the incident and reflected light vectors runs parallel to the y-axis, arranged in 5 rows and j max -columns, and a optical element O i,j , arranged in 6 rows and j max -columns, where the respective optical single channel K i,j is designed in this way, that when light enters the assembly 2, the area light modulators D i,j of the single channel K i,j the i-th row and the j-th column of a subset defined by the lighting assignment function b(i,j) according to b(i,j)⊂{Oi,j,O(i+1),j,O(i+2),j}with b(i,j)≠{Oi,j}and b(i,j)≠∅ or b(i,j)={{Oi,j,O(i+1),j},{Oi,j,O(i+2),j},{Oi,j,O(i+1),j,O(i+2),j},{O(i+1),j},{O(i+1),j,O(i+2),j},{O(i+2),j}} defined optical elements that are identically designed to each other (O i,j ) are illuminated, 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 as the row index i increases. 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 D i,j from the set defined by the projection assignment function p(i,j) according to p(i,j)={Oi,j} defined optical elements O i,jThe i-th row and j-th column are optically mapped, and all individual projection images of the system 2 are superimposed to form one or more virtual or real composite images on a screen 3. Individual channels with the same i-index are referred to as rows, and channels with the same j-index are referred to as columns. The numbering of i and j is ascending in the positive x- and y-directions, respectively, starting with index 1.

[0025] A surface light source 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 lying in the direction of the light source that 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.

[0026] The optical elements O 6,jIn this exemplary arrangement, they do not have a projecting function, but only serve to illuminate the last row of area light modulators D. 5,j of the array. The channels K 6,j They are therefore a special case and, unlike all other channels, do not have a dual function as lighting and projection channels, but are consequently only lighting channels.

[0027] 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 D i,j , these are rotated around an axis formed from their surface center and the y-unit vector of the system by the angle α DMD namely in such a way that the normal vector of the reflective pixel surfaces, which in the FLAT state pointed in the direction of the z-axis, is now tilted in the direction of the light source.

[0028] All optical elements O i,j In the exemplary arrangement shown, they are identical to each other. Channels adjacent in the x-direction are marked with O. i,j and O (i+1),j designated.

[0029] The (i+1)j-th optical element O (i+1)j is designed such that the light beam which reaches it from the light source 1 passes through the i,j-th area light modulator D i,j illuminated and the optical element O i,j , which is identical to the optical element of its neighboring channel O i+1,j is designed to be the area light modulator D i,j which is projected onto a screen as a real single image, and the totality of the individual images of all individual channels K i,j to completely superimpose a complete image on a screen 3 at a distance L1.

[0030] For large projection distances, the distance of the optical element O corresponds to i,jin the 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 single projection channel. Shown are the principal rays of the light beams effective for the image formation.

[0031] The system is designed in such a way that only light beams from the i-th channel K are used. i,j respective (i+1)-th neighboring channel K i+1,j the area light modulator D i,j , i.e., in the i-th channel row, such that the reflected light hits the optical element O corresponding to this area light modulator with row index i i,jcan effectively pass through as a projection lens and be 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 hits the center of the area light modulator D, should be i,j , coming from the (i+1)-th optical element, preferably meets twice the maximum deflection angle of the tilting mirror α dmd .(s. Fig. )

[0032] The optical axes of the individual projections of all individual channels K i,j exhibit, due to a defined difference in center distance between adjacent optical elements p Oi and p oj and adjacent area light modulators p di and p dj a convergence towards each other occurs, which ensures that all individual images on a screen 3 completely overlap to form a complete image at a distance L1.

[0033] The following applies: L1=fMKP⋅pOi(pDi−pOi)=fMKP⋅pOj(pDj−pOj)

[0034] Fig. shows the arrangement Fig. and instead of the main rays, the full light beams for the lowest pixel in the x-direction of the overall image.

[0035] Fig. shows the arrangement Fig. and instead of the main rays, the full light beams for the center of the overall image in the x-direction.

[0036] Fig. shows the arrangement Fig. and instead of the main rays, the full light beams for the highest pixel in the x-direction of the overall image.

[0037] Fig. shows the arrangement Fig. and instead of the ON state of all individual pixels of the area light modulator (as in Fig. (As shown) the normal vectors of the individual mirrors are now oriented along the z-axis. In DMDs, this is usually referred to as the FLAT state. In this pixel state, the arrangement ensures that the light beams striking the reflective surface light modulators are not imaged onto the screen 3 but instead end up in a beam trap 12.

[0038] Fig. shows the arrangement Fig. , in this case, instead of the previous orientation, the tilting mirrors are in the ON state ( Fig. ) the individual mirror surfaces now by the angle 2α DMD The system rotates clockwise around the axis defined by the pixel center and the y-unit vector of the system, relative to the light source. This represents the OFF state of the individual pixels of the area light source. All light beams striking OFF pixels are deflected less than in the flat state (see Figure 1). Fig. ) are deflected even further downwards and do not contribute to the image on the screen. To minimize stray light, they are directed into a beam trap 12.

[0039] Fig. shows the arrangement according to the invention. Fig. with five individual projections without convergence to each other. The individual channel projections are only converged with the aid of a biconvex lens 4 (converging lens) with a fixed positive focal length F. Makro at a distance F Makro The images are displayed on screen 3 to form a complete image and are combined by complete superimposition.

[0040] Fig. shows the arrangement according to the invention. Fig. with individual projection images which leave the array 2 without convergence, i.e., parallel to each other. The individual projection images strike a composite lens 5 with a variably adjustable focal length. This lens aligns the optical axes of the individual projections according to its set focal length (a negative focal length is shown in the image), so that the individual projection images can be convergent, parallel, or divergent to each other in the direction of a screen 3. This adjustable focal length enables variable image synthesis, allowing dynamic switching between different composite images with maximum illuminance and minimum number of images and minimum image size, or a composite image with maximum number of pixels, minimum illuminance, and maximum image size.

[0041] Fig. shows the arrangement according to the invention implemented by a combination of the individual surface light modulators D i,jin the form of a large-area composite surface 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 channel. The optical surface facing the surface light modulator 6 is a freeform surface, and the surface facing the screen is an aspherical surface. The effective light beams are shown for three different pixels in both the illumination beam path 13 and the projection beam path 14 (after reflection at the DMD). The light illuminating the i-th surface light modulator originates entirely from the adjacent channel with line index i+1 in the y-direction.

[0042] Fig. shows a specific embodiment of the invention. This is an arrangement of area light modulators D. i,jwith 5 rows and j columns, equipped with a cover plate positioned in front of it in the projection direction 8. The optical elements O i,j The individual channels, arranged in 6 rows and j columns, are each formed from two lenses, each with two optical surfaces. The optical assembly 9 is formed from two double-sided monolithic lens arrays, the first lens array 9a being a two-dimensional arrangement of the first lens from the optical element O. i,j and the second lens array 9b a two-dimensional arrangement of the second lens from the optical element O i,j contains. The illumination of the area light modulator D i,j This is achieved both through the optical element O (i+1)j as well as O (i+2)j The projection of the area light modulator D i,j This is achieved through the optical element O i,jFor 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.

[0043] Fig. Figure 1 shows the arrangement according to the invention, wherein the separation of the illumination beam path 13 and the projection beam path 14 of the individual channels is achieved by means of a monolithic prism 10. The light beams coming from the light source 1 of the illumination are totally internally reflected (TIR prism) at a side surface of the prism 10 due to their shallow angle of incidence and subsequently reach the assembly 2 at an oblique angle. Due to the reflective deflection and change in angle of the light beams at the area light modulators D i,j , any beam of light passing through the respective optical element O i,jThe image, which is projected onto a single projection image, is transmitted towards the screen 3 through prism 10 and through a second prism 11, which compensates for the refractive angular deflection of prism 10. This allows for a different arrangement compared to the one in Fig. An even more compact design is possible because the beam paths, even if they are not yet spatially separated, can be directed in different directions depending on the angle through total internal reflection, thus separating them within a minimal installation space. All individual projection images completely overlap to form a single image on screen 3.

[0044] Fig. The invention shows the beams of light in contrast to Fig. A prism 12 refractively passes through and reaches the assembly 2 without total internal reflection. Due to the reflective angular deflection at the surface light modulators D i,jand subsequent mapping by the optical elements O i,j The light beams in the projection beam path are totally reflected at an interface of prism 12 and thus deflected towards the screen. As also in Fig. The use of total internal reflection as an angle filter allows for a further reduction in the size of the overall system compared to the arrangement made of Fig. .

[0045] Fig. Figure 1 shows the invention in two different states. State 1 corresponds to a projection of a real overall image at projection distance L1 from the composite 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 Einzelflächenlichtmodulatoren erzeugt wird. Aufgrund der elektrischen Ansteuerbarkeit der Bildinhalte der Einzelflächenlichtmodulatoren kann vorzugsweise ohne mechanische Verschiebung der D i,j itself, but solely by shifting the image information onto the D i,j relative to each other, an effective change in the PDI can be realized, thus generating different distances for the synthesis of an overall image.

[0046] Fig. The invention is illustrated by way of 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 to at a tilt angle of α DMD to produce a telecentric illumination of the optical element.

[0047] Fig. shows the arrangement according to the invention Fig. ...supplemented by a reflector 15 in the illumination beam path. This serves to further miniaturize the arrangement.

[0048] Fig. shows a specific embodiment of the invention. It is an arrangement of area 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 each formed from two lenses, each with two optical surfaces. The optical assembly 16 is formed from two double-sided monolithic lens arrays, the first lens array 16a being a two-dimensional arrangement of the first lens from the optical element O. i,j and the second lens array 16b a two-dimensional arrangement of the second lens from the optical element O i,j contains.

[0049] The illumination of the individual area light modulator D i,j In this case, unlike in Fig. through the optical element O i,j as well as O (i+1)j i.e., the direct neighbors and a subset of the optical elements of its own channel. There is no cover plate in this arrangement. 8. The projection of the area light modulator D i,j This is achieved through the optical element O i,jFor each channel row with i ∈ {1, 2, 3, 4, 5}. Shown are the principal ray paths for the projections from the channel rows with i ∈ {1, 3, 5}.

[0050] Fig. shows the spatial and angular spatial distribution of light source 1 from the arrangement of Fig. The light source has a rectangular shape with a larger extent in the x-direction and a square angular distribution with divergence angles of approximately ±5° in the x- and y-directions.

[0051] Fig. shows the spatial and angular spatial distribution recorded in the plane of the screen-facing entrance surfaces of the optical elements O i,j The light from the light source strikes at a principal beam 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}.

[0052] Fig. shows the arrangement Fig. In 3D view. Shown is the beam path of three main beams coming from light source 1 for imaging the centers of the area light modulators D. 3j with j ∈ {1,2,3}. The following ray paths are shown as examples: O 41 illuminated D 31 and is by O 31 Projected in the direction of the screen. O 42 illuminated D 32 and is by O 32 Projected in the direction of the screen. O 43 illuminated D 33 and is by O 33 Projected in the direction of the screen.

[0053] Fig. In a particular embodiment of the solution according to the invention, the combination of two projection displays PD according to the invention is shown. a and PD b , PD a consisting of the light source 1a and the assembly 2a, and PD b consisting of the light source 1b and the assembly 2b.

[0054] The light source 1a is designed such that only the half of each area light modulator D that is furthest away from the light source in the x-orientation is illuminated. ai,j (shown as an example for the area light modulator D) a1,j with the lower half of the image 18 a1,j ) is illuminated. The projection display PD b corresponds to the projection display PD a , reflected at the center of the area light modulators D ai,j shifted yz plane. All pixels of all area light modulators are initially in the FLAT state. All area light modulators of the projection display PD a are from the projection display PD b , as well as the optical elements of the lines O ai,j i ∈ {1,2,3,4,5} is used together. Therefore, the following applies to 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 a5,1≡ O b1,j and for the area light modulators D a1,j ≡ D b5,j and D a2,j ≡ D b4,j and D a3,j ≡ D b3,j and D a4,j ≡ D b2,j and D a5,j ≡ D b1,j .

[0055] If one now inverts the image content of the channel-specific upper half of the image 17 ai,j (shown as an example with 17 a1,j for the channel (K a1,j )) of all area light modulators, these image contents are then applied to the projection displays PD b or, when light source 1b shines on 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 ai,jwith i ∈ {1, ...,5} projected towards screen 3. The combination of all channels can thus, through the interaction of all optical elements and both light sources, project a complete image with a correct distribution of illuminated and unilluminated areas, provided the tilting mirror states are correctly modulated.

[0056] Advantages of this arrangement of two combined projection displays (PD) a and PD b The technical requirements for the optical elements of each channel are lower, as they now only need to illuminate a significantly smaller area of ​​each adjacent channel or even project it internally. To avoid stray light in the projected 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 1a and 1b.

[0057] Fig. shows the arrangement Fig. In the z-view, illuminated by light source 1a, all 5x3 area light modulators are shown, with each illuminated only in its lower half by 1a. The area elements that act as ON pixels for light source 1a are hatched, while those that act as OFF pixels are shown in black.

[0058] Fig. shows the arrangement Fig. In the z-view, illuminated by light source 1b. All 5x3 area light modulators are shown, with each illuminated only in its upper half by 1b. The area elements that act as ON pixels for light source 1b are hatched, while those that act as OFF pixels are shown in black.

[0059] Fig. The merged projection image of all images of all lower image halves is shown 18 ai,j by PD a and all illustrations of all upper halves of the image 17ai,j by PD b on screen 3, consisting of a dark “F” in the center of a brightly lit square.

[0060] Fig. shows the exemplary superposition of two individual projection images on screen 3, where these are offset from each other in the x-direction and y-direction by P / 2, with P being the center-to-center distance of the projected pixels of an area light modulator D i,j of a composite 2, are shifted. This allows a doubling of the representable modulatable image pixel count in both the x-direction and the y-orientation, i.e., a quadrupling of the total representable pixels.

[0061] Shown are 2x2 projection pixels from the total set of all projection pixels of a single projection image, typically several hundred pixels in the x and y directions. This form of half-pixel superposition 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. This effect, commonly called lens shift, which creates a half-pixel image dimension in the x and y directions, can be realized either by decentering a subset of optical elements or by decentering a subset of area light modulators with respect to a regularly arranged array of optical elements with equal center-to-center spacing.Unlike conventional single-channel projection systems, which typically use high-frequency mechanics to realize this half-pixel superposition in a time-sequential manner, a multi-channel projection system implemented in this way can generate the increase in representable image information (super-resolution) without moving parts (solid-state).

[0062] Fig. shows the exemplary superposition of three individual projection images on screen 3, where these are offset from each other in the x-direction and y-direction by P / 3, with P being the center-to-center distance of the projected pixels of an area light modulator D i,j of a composite 2, are shifted. This allows a tripling of the representable modulatable image pixel count in both the x-direction and the y-orientation, i.e., a ninefold increase in the total representable pixels (superresolution). In contrast to Fig. This requires three subsets of channels K i,j, whose optical axes are deflected by either a 1 / 3 pixel shift or a 2 / 3 pixel shift in angular space to a first subset of optical channels. A 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 spacing, or by decentering a subset of area light modulators with respect to the entire set of optical elements with the same center-to-center spacing.

[0063] In a particular embodiment of the solution according to the invention, the paraxial focal length of the optically effective elements is preferably 0.5 mm - 30 mm.

[0064] An advantage of the solution according to the invention is that, due to the superposition of a plurality of area light modulators, each with a channel-specific spatial illumination distribution, on the screen 3, not only is the image information superimposed on the screen, but also all channel-specific spatial illumination distributions on the screen 3. i,j on screen 3. This inherent, arrangement-related mixing of the light distributions ensures better uniformity of light distribution across the entire image compared to conventional single-channel projection systems.

[0065] A conventional single-channel projection system that requires comparable homogeneity in the illumination of the overall image therefore always requires more effort, e.g., through a higher number of optical elements in the setup within the illumination beam path.

[0066] Due to the fact that, compared to a conventional projection system with the same luminous flux (depending on the number of channels N), it is approximately on 1 / N The significantly reduced required focal length of the optical elements necessary for imaging results in a significant potential for saving installation space by using the proposed multi-channel projection principle with the described reflective surface light modulators.

[0067] The dual function of the optical elements in each channel—that is, their use for both illumination and projection—results in enormous potential for component savings compared to conventional projection systems. This, in turn, can lead to significantly more powerful, less prone to malfunctions, and more cost-effective projection systems due to the resulting reduced complexity and tighter tolerances.

[0068] Applying the method described in DE 102011076083 A1 to the proposed solution according to the invention enables the projection of high-contrast, bright projection images onto, for example, steeply inclined screen surfaces or freeform surfaces. This is based on the multi-channel arrangement and 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 the usual projection distances (10 cm to 10 m).

[0069] The application of the object structure generation algorithms described in DE 102013208625 A1 can result in an extended depth of field compared to single-channel projection systems with the same luminous flux. In special cases, the calculation methods 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 a readjustment of the parameters on the area light modulators D. i,j requires trained object information.

[0070] Using area light modulators D i,jWith a pixel brightness depth (number of gray levels) controllable, for example, by 8-bit pulse-width modulation, a representable bit depth (number of representable gray levels) of 256 × N is achieved for a total image number of i · j = channels in the image. This corresponds to an increase in the representable gray levels or image depth due to the multi-channel superposition projection principle.

[0071] The exemplary design, shown in Fig. and Fig. , enables the use of the optical elements as a monolithic component for encapsulating the area light source and replaces the cover plate required in conventional projectors.

[0072] In a further particular embodiment of the solution according to the invention, it is proposed that within the assembly 2 a subset of projection channels K i,jChannel-specific color filters with the same column index j, with the same transmission spectrum, for example red, green or blue, are assigned, and the corresponding area light modulators D i,j The corresponding color component is represented as an ON pixel, thus creating a full-color overall image on the screen 3 by superimposing all channels colored in the primary colors K i,j results.

[0073] The application of the arrangement described in DE 10 2013 206 614 A1 in combination with the arrangement according to the invention disclosed here enables the projection of virtual image content, for example in the form of near-eye data viewing glasses or an arrangement for reflecting information into the field of vision of a motor vehicle occupant.

[0074] 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 format also corresponds to 16:9 or 1:1 due to the resulting optimal utilization of the area light modulators in combination with the usual spatial distributions of available light sources (high-performance LEDs, laser diodes).

[0075] One way to further increase 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, back into the illumination beam path a second or further time using additional optical components, so that it can pass through the illumination beam path several more times and thus possibly hit ON pixels on a further pass and be imaged towards the screen.

Claims

[1] Projection display comprising at least one light source (1) and at least one assembly (2) comprising at least two individual optical channels (K), each of which is formed from an area light modulator (D) which influences the direction of light propagation pixel by pixel, and an optical element (O), and in that for all channels of the assembly the inter-channel assembly of optical elements of all channels, when light enters the assembly (2), illuminates the area light modulator (D) in such a way that the optical element (O) of this channel maps the light reflected at the area light modulator (D) as an object structure, characterized by , that the assembly (2) consisting of individual optical channels K i,j , formed in a two-dimensional i × j 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: Ki,j=(Di,j,Oi,j)with i,j∈ℕ and j∈{1,…,jmax}and i∈{1,…,d}Ki,j=(Oi,j)with i,j∈ℕ and j∈{1,…,jmax}and i∈(d+1,…,o)and o≥d+1 with a surface light modulator (D) that can address the direction of light propagation pixel by pixel by reflection or a combination of reflection and diffraction i,j ), whose normal vector of the incident and emitted light vectors runs parallel to the y-axis, arranged in d-rows with d ≥ 2 and j max -columns, and an optical element (O i,j ), arranged in o-rows and j max -columns, where the respective optical single channel (K i,j ) is designed in this way, so that when light enters the assembly (2) the area light modulators (D i,j ) of the single channel (K i,j ) the i-th row and the j-th column of a subset defined by the lighting assignment function b(i,j) according to b(i,j)⊂{Oi,j,O(i+1),j,O(i+2),j}with b(i,j)≠{Oi,j}and b(i,j)≠∅ or b(i,j)={{Oi,j,O(i+1),j},{Oi,j,O(i+2),j},{Oi,j,O(i+1),j,O(i+2),j},{O(i+1),j},{O(i+1),j,O(i+2),j},{O(i+2),j}} defined optical elements (O i,j ) are illuminated, 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, 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 that is defined by the projection assignment function p(i,j) according to p(i,j)={Oi,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 overall images on a screen 3. [2] Projection display according to claim 1 or 2, characterized by , 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). [3] Projection display according to claim 1 or 2, characterized by , that a spatial separation of the illumination beam path (13) and the projection beam path (14) takes place by total internal reflection within a prism (10) which is arranged between the light source (1) and the assembly (2), so 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). [4] Projection display according to claim 1 or 2, characterized by , that within the network (2), projection channels (K i,j) with the same 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 ).

Images