WO2008090026A1 - Direction controlled illumination unit with deflection element - Google Patents

Abstract

The invention relates to a direction controlled illumination unit of an autostereoscopic display in which the light of activated illumination elements is displayed through a lenticular. Adjacent illumination elements are spaced horizontally and vertically apart from each other by means of bars for receiving electrical signal conductors, whereby inhomogeneities in the lighting and image reproduction arise. The aim of the invention is to provide an additional optical means for compensating for the bar images and thereby improving the imaging quality, requiring little space and improving, overall, light guidance in the above-described direction controlled illumination unit. To solve this problem, a large-area optical deflection element is proposed. The deflection element, the structure of which runs in rows and in conformity with a prespecified horizontal grid pattern of the illumination elements (BE) in which adjacent rows comprise differing structures and in which the structured rows repeat periodically, compensates for a horizontal misalignment (V), caused by the bar images, of a beam of light of adjacent activated illumination elements (BE), and said beam of light is directed onto an imaging element.

Description

 Direction-controlled lighting unit with deflection element

The invention relates to an autostereoscopic display with a directional lighting unit. The embodiment of the directionally controlled illumination unit according to the invention provides viewers with an improved display of two-dimensional and three-dimensional images or other information.

Areas of application of the invention are autostereoscopic displays for various commercial and private sectors such as the communications, TV and game console sector, research, medical technology and other fields.

Such autostereoscopic displays are characterized in that they provide visibility areas in a viewer space, which are automatically tracked with the help of a tracking and image control device to the eyes of different observers in their movements to other positions in this relatively large viewer space. Viewers' eyes can see from the visibility areas the images or other information displayed time-sequentially in the image display means, either in 2D or 3D mode or in mixed mode. Visibility areas are also referred to as sweet spots in other applications or patents of the assignee.

Autostereoscopic displays are in the document displays, where at least one viewer can see 3D images without any additional aids.

The main component of an autostereoscopic display incorporating the present invention is a directional lighting unit comprising, in the propagation direction of the light, substantially an illumination means having a plurality of light-irradiated or self-illuminating illumination elements and an optical imaging means having a plurality of semi-cylindrical imaging elements arranged parallel to one another. The imaging elements generate from the light of electronically activated illumination elements approximately parallel beams, which via a transmissive or reflective image display means are directed into the viewer space as a visibility area and overlap there. In this case, the light of a plurality of activated lighting elements always passes through an imaging element. The light beams are modulated in the image display means synchronously with stereoscopic image or other representations. If at least one left / right viewer's eye is located in the visibility region, then the viewer's eyes can perceive a 2D and / or 3D representation.

The visibility range can be specified in various forms and take in its extension one or both eyes of an observer. Even if the viewer occupies a new position in the space in front of the display, the 2D and / or 3D representations must constantly be available to him in good quality.

The directional lighting unit may include additional optical elements to improve the imaging relationships, such as fringe polarizers and diffuser means.

The lighting elements of the illumination means are, for example, the controllable cells of a light modulator, which are also referred to as pixels or subpixels and are arranged predominantly in a column-and-line manner in a regular manner.

Because of aberrations of optical systems, here preferably a lenticular, adverse effects may occur, such as inhomogeneous illumination and / or crosstalk of the visibility areas for the right and left eyes. They are largely compensated by appropriate measures.

In the patent DE 10 2005 012 348 of the applicant, for example, a direction-controlled lighting unit is used, which is used to reduce occurring optical problems in the three-dimensional representation of a Object for multiple viewers in the autostereoscopic display a special training an imaging means includes.

The imaging matrix contained therein also includes, in addition to a lenticular, deflection elements that are arranged periodically in groups in accordance with the vertical screening of an illumination matrix, each element of the group deflecting the radiation beams at a different predetermined angle. Each group of baffles repeats periodically in the rows and columns. These periodic repetitions of the groups of deflection elements increase the deflection range of the display. They deflect the beams in different directions in the space in front of the display in such a way that a plurality of horizontally offset visibility areas are formed according to the determined number of observer eyes. Provided optical means for vertical beam expansion to compensate for non-illuminated areas in the image matrix together with a scattering medium.

The optical scattering medium should continue to homogenize the unevenly illuminated areas for viewing the 2D / 3D representations in the image display means here. The inhomogeneities arise here firstly by the vertical group formation of the illumination elements, secondly, in principle, as a consequence of the inactive illumination elements in each column of the illumination matrix.

A further, third contribution to the inhomogeneities of the illumination is provided by the webs required for receiving the electrical signal lines between adjacent activated illumination elements, as shown in FIG. 1. In order to image all column-wise activated illumination elements under an imaging element, here a lenticle, with as few aberrations as possible minimizes the spherical aberration of the lenticle. This is achieved by slightly defocusing the optical distance between the illumination elements and the lenticular, but this leads to virtual, slightly visible images of the webs of adjacent illumination elements. Since no light is emitted from the bars, the edges of the lenticules receive less light and less appear on the image matrix as thin, darker vertical stripes that disturb the overall look of the 3D rendering.

The use of a scattering optical medium eliminates the first and second inhomogeneities, but not the very thin darker stripes caused by the ridges in 3D imaging. It has been proven in practice that the required small angle of scatter of the

Due to the production process, scattering mediums can not be exactly maintained over the entire surface of the image matrix. The necessary tolerances for the scattering angle required here are on the edge of the previously known technical feasibility.

The described disorders generally occur when using a lenticular in the imaging means and are the more disadvantageous the more observers want to see the displayed information and / or the less favorable the position of a viewer is to the optical axis of the display.

This results in the task of additionally using a simple optical means in the beam path which compensates for the ridge images and is therefore suitable for homogenizing the illumination of the autostereoscopic display and does not adversely affect the imaging quality of the imaging elements achieved. This means should take up little space and overall improve the light guidance in the above-described directionally controlled lighting unit, in order to enable several people to simultaneously view a homogeneously illuminated 3D display.

To solve the problem, a large-area structured optical deflection element is provided according to the invention, whose structure is line by line in accordance with a predetermined horizontal grid of lighting elements, in which adjacent rows have different structures and in which the structured rows repeat periodically. The deflection element is arranged in the direction of the light immediately behind an illumination means and deflects the light bundles of activated adjacent illumination elements by refraction such that a horizontal offset between adjacent light beams is compensated. The light bands! are directed to each detected imaging element, such as a lenticle, an imaging agent and channel the light at the same time.

In a first embodiment, one row of the optical deflecting element includes a plurality of planar elements, and the adjacent row includes a plurality of prismatic elements that are spaced apart and face the prismatic wedge in the same direction. Throughout the optical deflection element, one row of plan elements and one row of prism elements alternate. The plan elements of a row form one row, preferably a single plane surface. With this embodiment, a sufficiently large deflection of the light beam is achieved in order to compensate for the offset of adjacent light beams and to prevent the effect of the web image.

In a second embodiment, the optical deflector in each row includes a plurality of prism elements that are spaced apart and face the prism wedge in the same direction. The prism rows are arranged in the optical deflection element so that the prism elements of a prism row are aligned opposite to the prism elements of the adjacent prism row. As a result, the optically effective prism angle b of a prism element can be reduced compared to the first embodiment.

In a simple way, the horizontal offset of adjacent light beams is also compensated and prevents the effect of the web image.

The advantage here is further that the prism angle b manufacturing technology can be set very accurately and other optical effects such as birefringence does not occur. The arrangement and size of these prisms can be calculated so that the prisms are invisible to the human eye.

In a further embodiment of the invention, a structured line of the optical deflection element of a row of lighting elements of the Illuminant associated with the structure of the row in every other row of the deflection repeated.

For example, to compensate for a dimension of a vertical ridge of 15μm between adjacent lighting elements, the prism elements of a line must

have a prism angle b below 2 °,

- Have a vertical height h, which is less than or equal to the row height of the lighting elements, and - have an axial distance a of at most 1mm to the lighting elements.

To generate the necessary deflection of the light bundles, it is also expedient for a prism element arranged in a row to be at least 10 times larger in its horizontal dimension than the horizontal dimension of a web. Under this condition, it is possible to still accurately manufacture the prism elements and at the same time realize the required effect. In order to produce the optical deflection element cost-effectively, it is preferably formed in one piece.

The invention will be described in more detail below with reference to exemplary embodiments. The accompanying drawings show schematically in

Fig. 1 two separated by a web ST, activated lighting elements BE, which after imaging by an imaging element a

Offset V have, in perspective view as prior art,

2 is a plan view of the imaging beam path of two illumination elements BE and on the course of the intensity at a) uncorrected and b) approximately corrected offset V,

Fig. 3 is a plan view of a sectional view of a first embodiment of the invention with lighting elements BE, the Deflection element AE and an imaging element and different Strahlverläufen, and

Fig. 4 is a fragmentary perspective view of two adjacent rows of prism elements PE from a second embodiment.

The direction-controlled illumination unit of an autostereoscopic display, of which the invention is part, has already been described in detail in the front part of the description. Figures 1 to 4 contain further explanations of this unit, wherein in the figures 2 and 3 for better understanding of the invention, only the light bundle or light rays related to an imaging element are always shown. All other optical elements that are usually still present in the autostereoscopic display for intended use, but not directly related to the invention, such. Polarizing strips have been omitted in the figures.

The moistening elements BE can be pixels or, in the case of color representation, subpixels.

Fig. 1 contains, in a schematic arrangement, the essential means for illustrating the problem underlying the invention according to the prior art. Four illumination elements here represent a row of illumination elements of a matrix-shaped illumination means, which contains a multiplicity of such lines. Adjacent illumination elements of a row are separated by webs ST. As a result, the image of adjacent activated illumination elements, which are shown hatched, produces an offset V between the light bundles emanating from them.

In a top view, in FIG. 2 activated illumination elements BE with webs ST in front of an imaging element are shown symmetrically to the center line. As imaging means is a lenticular, of which only a lenticle LE is drawn as an imaging element. As is known, the lenticular has a multiplicity of one-dimensionally acting, mutually parallel Lenticules LE up. Furthermore, the imaging beam path of two adjacent, activated illumination elements BE _1, which are located approximately in the front focal plane of the lenticular LE, is shown, as well as the offset V of the light beams relative to one another. With a), the course of the light intensity for the illustration in FIG. 2 is shown, in which the drop of the intensity can be recognized by the offset V. The corrected intensity profile is represented by b) and can be achieved by an embodiment according to the invention corresponding to FIG.

FIG. 3 shows part of the directionally controlled illumination unit in a first embodiment according to the invention of a partially illustrated, line-wise structured optical deflection element AE. The plan view shows that a line with a strip-shaped planar element PL is followed by a line with prism elements PE. This structure of the lines repeats periodically over the entire deflection element AE.

In Fig. 4 is a partial perspective view of some prism elements PE of two adjacent rows of the deflection according to a second embodiment to see. This structure continues periodically up and down in the deflector. Furthermore, the vertical height h of a prism element PE is drawn, which may be less than or equal to the height of a line of the lighting elements.

With reference to the controllable illumination device of an autostereoscopic display with a lenticular imaging means, the invention is described in more detail. As is known, synchronously with the light, the image information is displayed as stereo images in a preferably transmissive reproduction means sequentially to at least one observer.

By a position detection system (not shown), the positions of observer eyes are determined and a control unit (not shown) activates a certain number of lighting elements BE, ie they are switched translucent. The illumination elements BE of a lighting means are horizontal and vertical in a predetermined grid arranged. The light coming from the illumination elements BE is, according to FIG. 2, after passage through a lenticle LE, shaped into approximately parallel light bundles which form a visibility region in front of the reproducing means (not shown). From here, eyes of the viewer can be known to see a 3D representation, whereby for each viewer a homogeneous homogeneous illumination of the image display means is always to be ensured. This is achieved by a large-area, structured optical deflection element AE between the illumination means and the imaging means in FIG.

As shown in FIG. 3, the light emitted from both horizontally and vertically selected activated illumination elements BE hits the optical deflection element AE and propagates in different directions in front of the lenticle LE, which is indicated by arrows.

The structure of one row of the deflecting element AE is formed by a plurality of prism elements PE or a plurality of plane elements PL which add up to a total plane in the line. The prism elements PE of a row show the prism wedge in the same direction without any distance from one another. In each case a structured line of the deflection AE is assigned a row of lighting elements BE.

When incident on the prism elements PE of the deflection element AE, the light is deflected in such a way that the light missing from the webs ST, recognizable from the dashed continuation of the arrow lines, is compensated. At the same time, it is also prevented with the prism elements PE that lines of the lenticle LE arising due to the slight defocusing of the lenticular become visible. This is achieved by a predetermined geometric design and a predetermined arrangement of the prism elements PE in the deflection AE.

According to one exemplary embodiment, the prism elements PE are calculated in such a way that they have, for example, a size of the vertical webs ST of 15 μm-a wedge angle b of less than 2 °, have a vertical height h which is less than or equal to the height of a line of the wetting elements, and

- Have an axial distance a of at most 1 mm to the lighting elements.

With these parameters, the offset V of the light bundles caused by the vertical webs ST is compensated. Practically, the light of the lighting elements BE scatters the size of the vertical webs ST, so that they are no longer visible. In addition, it is achieved by the prism elements PE that the light is channeled toward the lenticle LE. The deflection element AE in this example includes a row of prism elements PE and a row of plan elements PL, which alternate with each other.

After passing through the lenticular LE and the image display matrix, modulated light passes to the visibility region and can be here e.g. be seen as a 3D representation of observer eyes.

This first embodiment can be produced technologically simple.

A second embodiment differs from FIG. 3 in that the deflection element AE contains only lines with prism elements PE. The prism elements PE of a row are likewise arranged without spacing from one another and point in the same direction with the prism wedge. However, the prism lines are arranged so that the prism elements PE of adjacent prism lines point in opposite directions, which is apparent from the schematic perspective view in FIG. As a result, it is achieved in the deflection element AE that the adjacent prism elements PE always point in a column of prism elements PE in the opposite direction. Since only wedge surfaces contribute here to deflect the light bundles, the optically effective keying angle b and thus also the edge of a prism element PE can be reduced in contrast to the first embodiment. For an implementation of the second embodiment, there is the advantage that the deflection element AE can thus be made flatter and nevertheless the necessary horizontal deflection of the light beam of adjacent illumination elements BE is maintained. A further contribution to this is that a prism element PE arranged in a row is at least 10 times larger in its horizontal dimension than the horizontal dimension of a web ST.

The inventive arrangement and design of the optical Abfenkelements AE in a directional lighting unit of an autostereoscopic display over the prior art, the homogeneity of the illumination is improved and increases the imaging quality.

Bezuqszθichen:

AE deflection element

BE - lighting element

LE - Lenticle

PE prism element

ST - bridge

V - offset a Distance between BE and AE b - prism angle h - vertical height

Claims

claims 1. Device for deflecting light bundles in a direction-controlled lighting unit of an autostereoscopic display, wherein - the lighting unit is a lighting center! with luminescent elements arranged in a raster, which are mutually separated by webs for receiving electrical signal lines, and containing imaging means illuminated by the illuminating means with imaging elements arranged parallel to one another, and the device for deflecting as a large-area optical deflecting element with rows of prismatic elements , which are arranged in each case in a row without spacing and with their prism wedges pointing in the same direction is formed, characterized in that the large-area optical deflection element (AE) is arranged in the light direction immediately behind the illumination means and the light beam of activated adjacent illumination elements ( BE) is deflected horizontally by refraction at the wedge surfaces of the prism elements (PE) so that the effect of the vertical webs (ST) of adjacent illumination elements (BE) is compensated for and the light bundles in each case s are directed to an imaging element associated with the activated lighting elements (BE). 2. Device according to claim 1, wherein the prism elements (PE) of a prism row opposite to the prism elements (PE) of the adjacent prism row are arranged in order to reduce the optically effective prism angle (b) of the prism elements (PE). 3. Device according to claim 1, wherein a plurality of arranged in a row prism elements (PE) are associated with an imaging element and a prism element (PE) in its horizontal dimension at least 10 times greater than the horizontal dimension of a web (ST). 4. Device according to claim 1, wherein the prism elements (PE) have a wedge angle (b) of less than 2 °, have a vertical height (h) which is less than or equal to the height of a line of the lighting elements (BE), and - Have an axial distance (a) of at most 1 mm to the lighting elements (BE).