DE10015796A1 - Illumination device for auto-stereoscopic display, has controllable birefringent material between filter array and mask - Google Patents

Abstract

The device consists of at least one light source (1), a mask (2) comprising a number of opaque elements and transparent elements, and an array of wavelength filters. A controllable optical birefringent material (3) is provided between the array and the mask, and is provided with a drive unit (4). According to the set birefringent effect of the material (3), a two-dimensional or a three-dimensional illumination mode.

Description

The invention relates to a lighting arrangement for an autostereoscopic Display, which in particular switches between a 3D and a 2D mode enables.

In the published US 58 97 184 narrow lighting for autostereoscopic displays presented. Here an extended light guide is used Notches or knobs provide the structured lighting necessary for 3D operation produce. The disadvantage here turns out that the waveguide only with high Effort can be produced and the system is essentially only for the other two-channel process is suitable.

The laid-open specification US 53 49 379 describes a lighting system for autostereoscopic displays in which a large number of narrow elongated lamps it is controlled that an image composed of two perspective views is structured is illuminated, whereby the image can be perceived three-dimensionally. The disadvantage here is u. a. the high number of lamps required and the usability of the lighting exclusively for two-channel 3D displays.

Other arrangements and procedures, e.g. B. JP 3119889, use to generate the Type according to known barrier patterns LC displays, which enables a purely technical switchover between 2D and 3D mode. The disadvantage here is that two Image display devices must be used, which makes the arrangements significantly more expensive become. Another disadvantage of this arrangement is that they are used as a barrier LC displays are currently far from being in large-format dimensions above 30 inches (Screen diagonal) are available and therefore not unrestricted for assembly can serve, for example, large-format plasma displays. Moreover, step through the Use of similar structures for both lighting and image display unpleasant moiré effects.  

Starting from this prior art, the invention is based on the object with simple means a lighting arrangement for a preferably multi-channel autostereoscopic display to enable a technical switch between a 3D and a 2D mode. In the 2D mode, one is supposed to conventional lighting for two-dimensional display devices comparable Illumination homogeneity can be achieved.

The usability of the arrangement according to the invention for an autostereoscopic display should result from the fact that a suitable wavelength filter array is implemented. Arrangements for three-dimensional representation using Wavelength filter arrays are known in the prior art; thereby the Image information of different perspective views, which on the RGB subpixels of a Display device are shown, defined by the effect of the wavelength filter Direction of propagation assigned.

This principle can e.g. B. can also be realized by an illuminated Wavelength filter array as lighting for a translucent image display device, e.g. B. a color LC display is used. In particular, orders of this type autostereoscopic display using wavelength filters The lighting arrangement according to the invention is described below.

The lighting arrangement according to the invention for an autostereoscopic display consists of at least one - preferably planar - light source ( 1 ), a mask ( 2 ) with a variety of opaque and transparent surface elements and an array of wavelength filters ( 5 ). This structure is schematic and is not shown to scale in FIG. 1. The mask ( 2 ) has a structure corresponding to the structure of the array of wavelength filters ( 5 ). Opaque elements of the array of wavelength filters ( 2 ) are on the mask ( 2 ) in the same shape and size as likewise opaque surface elements and non-opaque ( e.g. R ', G', B ') Elements of the array of wavelength filters ( 5 ) are formed on the mask ( 2 ) in the same shape and size as transparent surface elements. The mask ( 2 ) could therefore also be referred to as a "diaphragm array".

The opaque elements of the array of wavelength filters ( 5 ) themselves are designed according to the invention as scattering surface elements (L), for. B. as rough surfaces or diverging lenses.

According to the invention, a controllable optically birefringent material ( 3 ) of thickness z, which is provided with a control ( 4 ), is additionally arranged between the array of wavelength filters ( 5 ) and the mask ( 2 ). The surface of the material ( 3 ) facing the mask ( 2 ), onto which the light coming from the light source ( 1 ) is incident, must be at an angle to the optical axis (OA) of the material ( 3 ). This is indicated in Fig. 1 with the double arrow (OA).

The controllable optically birefringent material ( 3 ) can be, for example, a birefringent crystal that shows the Pockels or Kerr effect. Accordingly, the control ( 4 ) is designed so that it is able to generate a switchable electric field at least within the spatial extent of said crystal in order to influence the birefringent properties of the crystal.

If for the purpose of lighting an autostereoscopic display, the component ( 3 ) is controlled by the control unit ( 4 ) assigned to it so that the beam path does not show birefringence when it passes through the same element ( 3 ), so essentially due to the mask ( 2 ) only the non-opaque filter elements of the array ( 5 ) are illuminated. The elements which are opaque for the wavelength filter array ( 5 ), but which are designed as scattering elements (L) in an arrangement according to the invention as described, are only illuminated to a negligible extent. The 3D lighting mode is active.

As noted above, such lighting, e.g. H. an illuminated or self-illuminating wavelength filter array for illumination in an arrangement for three-dimensional representation can be used. For this, z. B. in a particular Distance d a translucent image display device (e.g. a color LC display) can be arranged upstream. This image display represents a suitable combination image from z. B. Eight perspective views represents.

If the control unit ( 4 ) - for the purpose of a two-dimensional representation - switches the component ( 3 ) to birefringent behavior, the behavior illustrated in FIG. 2 occurs:
Linearly polarized light of a certain polarization direction (e.g. polarized perpendicular to the plane of incidence on the component ( 3 )) passes through the element ( 3 ) as in the unaffected case and illuminates the non-opaque filter elements (e.g. R ', G' , B ') of the array ( 5 ). This is illustrated in FIG. 2 by the rays (“ordinary beams”) designated (O).

The light component originating from the light source ( 1 ), which is linearly polarized perpendicular to the polarization direction just mentioned, is now deflected ("broken away") by the now birefringent material from the original direction of propagation. The result is the extraordinary rays (EO) (for "extraordinary beams"), which illuminate the scattering elements (L). As a result, the lighting effect of the arrangement appears more homogeneous; an image display device located in front of this arrangement can be operated as a normal 2D image display device using the full image resolution. For this mode, the control unit ( 4 ) should preferably control the component ( 3 ) in such a way that light components pass through both the non-opaque elements (R ', G', B ') of the array ( 5 ) and through the scattering elements (L) .

An autostereoscopic device using this lighting arrangement according to the invention Display device, can thus be used as an ordinary 2D display using the full resolution or operated as a 3D display.

So that the described lighting according to the invention is fully functional, the light originating from a light source ( 1 ) must either be unpolarized or circularly polarized.

In arrangements for three-dimensional representation using wavelength filter arrays, the structure on the array can be varied; that is, the structure of the wavelength filter array partial shown in Fig. 1 and Fig. 2 (5) and the structure of the mask (2) are accordingly to be regarded as examples only.

In order to further increase the luminous efficacy of the arrangement according to the invention, the following expansions of the arrangement described so far, which are shown schematically in FIG. 3, are preferably also possible:

In the event that the structure resulting for the mask ( 2 ) has essentially slit-shaped transparency areas, a planar light source ( 1 ) can be replaced by rod-shaped lamps ( 1 ') which are aligned in the same direction as the slit-shaped transparency areas just below (at least some of) them.

This arrangement can be further improved by curved mirrors ( 6 ), which are arranged behind the lamps ( 1 ') in the viewing direction in such a way that the reflections emitted by them "bundle" the light through the transparent diaphragm elements of the mask ( 2 ).

In order to better channel the light of the lamp elements ( 1 ') or light source ( 1 ) in 3D mode, a waveguide effect can be used.

For this purpose, the controllably birefringent material ( 3 ) is formed as an array consisting of small, preferably cuboid, controllably birefringent elements ( 3 ') and further - compared to the elements ( 3 ') - optically thinner and non-birefringent, preferably cuboid, elements ( 7 ). The elements ( 7 ) are preferably arranged between the scattering surface elements (L) of the wavelength filter array ( 5 ) and the opaque elements of the mask ( 2 ), while the elements ( 3 ') are preferably between the non-scattering elements of the wavelength filter array ( 5 ) and the transparent surface elements of the mask ( 2 ) are arranged. The elements ( 3 ') can also replace said transparent surface elements of the mask ( 2 ). Furthermore, the elements ( 3 ') can be controlled by an adapted control ( 4 ') in their optically birefringent properties.

The aforementioned waveguide effect occurs in that light passes through the cuboid elements ( 3 ) 'which are surrounded by a (non-birefringent) optically thinner medium ( 7 ).

The cuboid optical elements ( 3 ') can also be replaced by the type known from Nicol, Rochon, Sénarmont or similar crystal polarizers, it being possible for the birefringence to be switched on by designing the crystal polarizers with appropriate materials and controls.

Due to the waveguide effect, the light in the 3D mode is guided to the translucent filter elements of the array ( 5 ) with less loss, while the 2D mode still remains switchable, as is also illustrated in FIG. 3.

It is also possible to control elements ( 3 ) or ( 3 ') from controllable birefringent material for the 2D mode in a periodically changing manner. The resulting periodically fluctuating conditions of the two partial beams (O, EO) allow a more homogeneous 2D illumination to be achieved.

In a preferred embodiment based on the scheme according to FIG. 1 or FIG. 2, the switchable birefringent material ( 3 ) is a Pockels cell and consists, for. B. from lithium niobate (LiNbO ₃ ) or potassium diphosphate (KH ₂ PO ₄ ) with a thickness of 1 mm. The Pockels cell ( 3 ) is extended in terms of area between the mask ( 2 ) and the modified wavelength filter array ( 5 ), it also being possible to combine a plurality of individual crystals of the materials mentioned to form a total area as birefringent material ( 3 ).

The surface of the Pockels cell ( 3 ), on which the light originating from an areally extended light source ( 1 ) is incident, must be inclined to the optical axis (OA), e.g. B. at an angle of 20 °. The light source ( 1 ) can, for example, be one that is used in LC displays (eg from Sanyo).

The control ( 4 ) for the Pockels cell ( 3 ) consists of an adjustable voltage generator and two electrodes, which are attached to the top and bottom of the Pockels cell (if it stands vertically like a normal screen). An exemplary structure of a wavelength filter array ( 5 ) modified according to the invention is shown in detail in FIG. 4. R ', G', B 'each represent filter areas of the corresponding transparency wavelength ranges of the R, G, B colors and (L) stands for a scattering surface element, e.g. B. a lens element.

A corresponding aperture structure for the mask ( 2 ) is shown in detail in FIG. 5. Herein (T) means a transparent element, while (S) stands for a completely opaque section.

The wavelength filters of the array ( 5 ) can be applied to the controllably optically birefringent material ( 3 ), for example by a printing process (e.g. screen printing, offset printing), while the scattering surface elements (L) can be applied by etching the surface of the controllably optically birefringent material Materiales ( 3 ) are generated.

The mask ( 2 ) can advantageously be produced by an exposure process.

In Fig. 7, a specific application of the invention in an autostereoscopic display is not to scale and illustrates in phantom. For example, in front of the lighting arrangement according to the invention (see modules 1-5 ), a color LC display ( 8 ) with control electronics ( 9 ) can be arranged at a distance d = 3 mm (distance of the mutually facing surfaces), which is suitable Combination image of several views, preferably perspective views.

If, for this exemplary arrangement for the 3D representation according to FIG. 7, that is to say for an autostereoscopic display, eight perspective views are used as an example, the image-displaying LC display ( 8 ) in this embodiment variant should preferably be a combined overall picture of the perspective views according to FIG. 6 demonstrate. The image information is obtained from the subpixels of the eight perspective views and combined to form the overall image; each sub-pixel shown has the exact same position in a given image grid format in the perspective view and in the combined overall image. For this purpose, all perspective views and the combined overall image preferably have the same grid format; In this specific example, the views or the overall picture are divided into a grid with 800 columns and 600 rows. An LC display ( 8 ) of the Sanyo LMU-TK12A type is suitable for displaying such an image grid.

The image combination and image generation on the LC display ( 8 ) can be ensured by the electronic control ( 9 ). The columns designated R, G, B in FIG. 6 correspond to columns of the subpixels of the image-displaying display device ( 8 ), each with the displayable colors red, green and blue.

In the application example described in an autostereoscopic display, it must also be noted that the direction of polarization of the light passing through the filter surfaces R ', G', B 'on the array ( 5 ) modified according to the invention corresponds to the direction of the polarization filter of the color LC display on the illumination side ( 8 ) matches. This is achieved by suitable alignment of the corresponding components.

In the event that the controller ( 4 ) does not supply the Pockels cell with an electrical voltage, ie that no electrical field is effective there, the overall arrangement described acts as an autostereoscopic 3D display, since the variety of filter surfaces R ', G', B '' acts as structured lighting for the color LC display ( 8 ) and only individual directions of light propagation are made possible for the individual image information of the various perspective views shown in the combination image there. The elements of the wavelength filter array ( 5 ) designed as scattering elements (L) are almost not illuminated in this case.

However, z. B. via the controller ( 4 ) to the material ( 3 ), ie to the Pockels cell, an AC voltage of 5000 V at z. B. 100 Hz, the birefringent effects result in an almost homogeneous illumination, which means that the color LC display can also be used as a 2D display using the full resolution. The scattering disc elements (L) on the array ( 5 ) modified according to the invention not only cause diffuse scattering of the radiation directions of the light passing through these elements, ie the extraordinary rays (EO). Said light is also converted into unpolarized light at the same time, which means that the light can be used for the color LC display, since the extraordinary beam (EO) is polarized perpendicular to the ordinary rays (O) and the direction of polarization of the ordinary rays (O) , which pass through the wavelength filters R ', G', B ', coincides with the transmission direction of the illumination-side polarization filter of the LC display ( 8 ).

In general, when using diverging lenses as diffusing elements (L), the lenses in Viewing direction 90 ° polarization rotator, preferably half-wave plates (e.g. for 555 nm) to assign suitable polarization ratios for the LC display produce.

The switchable birefringence can e.g. B. also about the Kerr and Faraday effect can be achieved. Mechanical stress can also cause such behavior. Of course, all arrangements are included in the invention, according to the way described use media, which in yet another way controllably induce birefringent behavior.

In a special embodiment, the wavelength filter array ( 5 ), including the scattering elements (L) formed instead of the opaque surface elements, can be designed as a holographic optical element (HOE).

The embodiment of the invention can also be designed in such a way that switching between 2D and 3D mode on selectable partial areas of an arrangement for spatial representation is made possible. For this purpose, the control ( 4 ) or ( 4 ') must be designed such that it can control the birefringent effect of certain partial areas of the material ( 3 ) or ( 3 ') independently of other partial areas of said materials. In all figures, only a few of many possible beam paths are shown as examples. Furthermore, none of the drawings are drawn to scale.

The dispersion effects that occur impair the functioning of the described Arrangement only marginal.

The described invention can be used in many ways in use in autostereoscopic arrangements, e.g. B. in construction programs that optionally require a two- or three-dimensional representation or for the representation of medical matters, in which, for example, 3D ultrasound data are to be spatially shown on the same display as, for. B. Anamnesis data or the like. Switching between 2D and 3D modes is advantageously possible purely technically, ie, for example, with a software control that controls the control ( 4 ) or ( 4 ').

Reference list

R 'Color filter that is permeable to the primary color range red
G 'color filter that is transparent to the primary color range green
B 'color filter which is permeable to the primary color range blue
R Designation for red subpixels or columns
G Designation for green subpixels or columns
B Designation for blue subpixels or columns
L scattering surface element (e.g. diffuser)
OA optical axis
O neat beam
EO extraordinary beam

1

area lighting

1

'' different form of lighting

2

Mask with a variety of transparent and opaque surface elements

3rd

controllable birefringent material (e.g. Pockels crystal)

3rd

'' controllable birefringent material

4

Control for (

3rd

)

4

'' other form of control, especially for (

3rd

')

5

Wavelength filter array modified according to the invention

6

mirror

7

non-birefringent optical material

8th

Color LC display

9

Control for (

8th

)
d distance from (

5

) to (

8th

)
z thickness of the material (

3rd

)
S opaque surface element
T transparent surface element

Claims (8)

1.Lighting arrangement for an autostereoscopic display, which can optionally also have a largely homogeneous lighting effect, consisting of at least one light source ( 1 ), a mask ( 2 ) with a large number of opaque and transparent surface elements and an array of wavelength filters ( 5 ), characterized that

• - The mask ( 2 ) has a structure corresponding to the structure of the array of wavelength filters ( 5 ), opaque elements of the array of wavelength filters ( 5 ) on the mask ( 2 ) in the same shape and size also as opaque surface elements and non-opaque elements the array of wavelength filters ( 5 ) are formed on the mask ( 2 ) in the same shape and size as transparent surface elements,
• - The opaque elements of the array of wavelength filters ( 5 ) are designed as scattering surface elements (L),
• - A controllably optically birefringent material ( 3 ) of thickness z, which is provided with a control ( 4 ), is arranged between the array of wavelength filters ( 5 ) and the mask ( 2 ),
• - The surface of the material ( 3 ) facing the mask ( 2 ), onto which the light coming from the light source ( 1 ) is incident, is at an angle to the optical axis (OA) of the material ( 3 ),
• - whereby the lighting arrangement in arrangements for autostereoscopic display ("autostereoscopic displays") advantageously allows a 2D or 3D lighting mode depending on the optically birefringent effect of the material ( 3 ) set.

2. Arrangement according to claim 1, characterized in that the controllable optically birefringent material ( 3 ) is a birefringent crystal, for. B. lithium niobate, which shows the Pockels or Kerr effect and the control ( 4 ) is able to generate an electric field at least within the spatial extent of said crystal. 3. Arrangement according to one of the preceding claims, characterized in that the light source ( 1 ) is extended in terms of area or is formed by a plurality of individual lamps which can be supplemented with curved mirrors for the purpose of bundling light. 4. Arrangement according to one of the preceding claims, characterized in that the controllably birefringent material ( 3 ) is formed as an array consisting of small, preferably cuboid, controllably birefringent elements ( 3 ') and - compared to the elements ( 3 ' ) - optically thinner and non-birefringent, preferably cuboid, elements ( 7 ), the elements ( 7 ) preferably being arranged between the scattering surface elements (L) of the wavelength filter array ( 5 ) and the opaque surface elements of the mask ( 2 ), while the elements ( 3 ') are preferably arranged between the non-scattering surface elements of the wavelength filter array ( 5 ) and the transparent surface elements of the mask ( 2 ), wherein the elements ( 3 ') can also replace said transparent surface elements of the mask ( 2 ) and the elements ( 3 ') of an adapted control ( 4 ') in their optical birefringent properties can be controlled. 5. Arrangement according to one of the preceding claims, characterized in that

• - The wavelength filters of the array ( 5 ) are applied to the controllable optically birefringent material ( 3 ) by a printing process (e.g. screen printing, offset printing),
• - The scattering surface elements (L) are produced by etching the surface of the controllable optically birefringent material ( 3 ), and
• - The mask ( 2 ) is produced by an exposure process.

6. Arrangement according to one of claims 1-3, characterized in that the wavelength filter array ( 5 ) including the instead of the opaque surface elements formed scattering elements (L) is designed as a holographic optical element (HOE). 7. Arrangement according to one of the preceding claims, characterized in that the thickness z of the material ( 3 ) is from 0.5 to 10 mm. 8. Arrangement according to one of the preceding claims, characterized in that the control ( 4 ) or ( 4 ') is designed such that it in certain sub-areas of the material ( 3 ) or ( 3 ') independently of other sub-areas of said materials can control their birefringent effect.