WO2001092954A1

WO2001092954A1 - Video projector attachment for 3-d projection of stereo images

Info

Publication number: WO2001092954A1
Application number: PCT/EP2000/004994
Authority: WO
Inventors: Stefan Naumann; Rudolf Friedemann; André Volke; Hans-Joachim Cornelius
Original assignee: Codixx Ag
Priority date: 2000-05-31
Filing date: 2000-05-31
Publication date: 2001-12-06
Also published as: DE10192272D2; AU5677300A; WO2001092955A1; AU2001260330A1; DE10192272B4

Abstract

The invention relates to an attachment for a light-emitting video projector, the beam of which contains a left and right stereo half-image adjacent to each other, for the 3-D projection of stereo images on a projection surface, upon which the projection planes are essentially maintained for observation with polarised spectacles. The aim of the invention is to develop a generic attachment in order to avoid the disadvantages of the state of the art and with which stereo images are produced on a projection surface, essentially retaining the polarisation planes and which may be observed with simple polarised spectacles. Said aim is achieved, whereby in one embodiment of the attachment, said attachment, comprises two rotatably arranged mirrors (2) and a filter with a retarding film (3), for rotating the direction of polarisation of the light by 90°. The retardation filter (3) and the two mirrors (2) are aligned relative to each other such that only the light beam of one of the both stereo half-images is rotated by the retarding filter (3) in the polarisation direction thereof and both stereo half-images are projected upon each other on the projection surface (5).

Description

Attachment for video projectors for 3-D projection from

stereo images

The invention relates to an attachment for video projectors for 3-D projection of stereo images according to the preambles of claims 1, 4, 8.

Stereo images, in particular moving stereo images, are, according to the known state of the art, expensive hardware, such as Workstations with 3-D graphics options and frequency-controlled LC glasses, accessible on the screen or through the use of expensive multi-beam devices for projection surfaces (US 45 04 856 and IWASAKI et al. 3-dimensional personal computer system, in: IEEE Transactions on Consumer, Electronics , Vol. 34, No. 3 August 1988, pp. 536-542).

Alternative solutions by using an optical attachment for single-beam video projectors have been presented as a prism construction in JP 09281616 or as a mirror construction in DE 196 08 362.

DE 195 25 871 Cl further describes devices for recording and reproducing electronic spatial images by means of a video camera or a video projector. The video projector attachment for the reproduction of the spatial images consists of an elaborate mirror prism construction with two polarization filters.

The object of the invention is to develop a generic attachment with which the disadvantages of the prior art are avoided and with which stereo images are generated on a projection surface on which the polarization planes are largely maintained, which can be viewed with simple polarization glasses. According to the invention, this object is achieved by the features of claims 1, 4, 8. The attachment according to claim 1 is characterized in that at least two rotatably arranged mirrors and a filter with a retardation film are provided for rotating the polarization direction of the light by 90 ° and the retardation filter and the two mirrors are adjusted to one another such that only the light beam is one of the two stereo fields are rotated in their polarization direction by the retardation filter and both stereo fields are projected onto one another on the projection surface.

The attachment according to claim 4 is provided for an unpolarized light and / or linearly polarized light emitting single-beam video projector, in the beam of which a left and a right stereo field are arranged spatially next to one another for 3-D projection of stereo images on a projection surface, in which the polarization planes are largely maintained, for viewing with polarization glasses, the attachment being formed from at least one movable mirror for one stereo field and from a beam splitter such as Nicols prism for the other stereo field.

The attachment according to claim 8 is provided for a light-emitting single-beam video projector, in the beam of which a left and a right stereo field are arranged spatially next to one another, for 3-D projection on a projection surface for viewing with polarizing glasses, the attachment consisting of a unit for generating linearly polarized light for the left and right fields, a unit for superimposing the two fields, an optical component for rotating the polarization plane through 90 °, and a unit for mixing the two fields polarized perpendicular to one another. In this embodiment, differently polarized light can be used depending on the wavelength (linear, partial, elliptical circular, unpolarized). With the embodiment, an exactly superimposed image is achieved with reduced adjustment effort.

In a preferred embodiment of this variant of the attachment, the attachment consists of one beam splitter for each stereo field, one mirror for each stereo field, and one retardation filter (λ / 2 plate) for each half of each stereo field consists of one optical element per stereo field, which superimposes two parallel beam paths to form a beam output, further mirrors and a further beam controller, which together mix the two stereo fields with their complementary polarization planes to form a stereocoded output image, the optical elements being arranged with respect to one another in such a way that the polarization planes of each stereo field are separated, one of the two separated components is rotated, the components are mixed to form a parallel beam path in such a way that for each stereo field there is an image at 90 ° rotated plane of polarization , which are mixed via the further beam splitter.

Appropriate embodiments are specified in the subclaims.

The advantages achieved with the invention consist in particular in that the previous constructions are considerably simplified and the quality of the 3-D image reproduction is significantly improved. This is mainly achieved by eliminating a fixed mirror and two polarization filters and using a retardation filter. This makes the light absorption of one stereo field clear and that of the other even to zero, so that more brilliant 3-D images are projected. This also has the positive effect that presentation rooms are no longer as strong as before must be darkened. In addition, the adjustment effort in the attachment according to the invention is less. In principle, the attachment can be placed on any LCD single-beam video projector. The stereo fields generated spatially next to one another with graphics software or a stereo camera

alternatively from a video cassette or on-line via PC or graphic workstation via the video projector.

The resolutions according to the invention provide easy access to the projection of moving stereo images, in particular for lecturing in teaching, research, school lessons. Such presentations are of particular interest for the mediation of spatial vision of moving images in chemistry, biochemistry, medicine and architecture.

The invention is explained in more detail below using exemplary embodiments of attachments. In the accompanying drawing:

1: the schematic representation of a first embodiment of the attachment,

2: the schematic representation of a second embodiment of the attachment,

3: the schematic representation of a third embodiment of the attachment,

Fig. 4: the schematic representation of a

Variant of the third embodiment according to FIG. 3,

Fig. 5: the schematic representation of a fourth embodiment of the attachment and

Fig. 6: the schematic representation of an embodiment of a mixing unit. In a first embodiment of the invention, as shown in FIG. 1, there is the optical attachment for a linearly polarized light-emitting video projector

1 consisting of two rotatably arranged mirrors S and a correspondingly positioned filter with a retardation film 3, which are adjusted relative to one another in such a way that the direction of polarization of the light beam is only rotated by 90 ° from a stereo field. The two stereo fields of the stereoscopic representation generated next to one another are projected onto one another on a projection surface PF. A diaphragm 4 is arranged on the attachment in such a way that disturbing reflections caused by scattered light from the attachment on the edges of the projection surface are prevented.

With the help of simple polarizing glasses and using a polarized light reflecting projection surface PF, 3-D images can be viewed.

Cheap, light-scattering plastic films can also be used as a reflecting projection surface PF which maintains the polarization planes, instead of expensive screens.

An advantageous embodiment of the attachment according to claim 1 provides that, as shown in FIG. 2, the mirror S2 applied in the region of the lens center is semitransparent and the further mirror S1 is a surface mirror. The mirrors S1, S2 can be rotated a few degrees perpendicular to the projection plane in order to place the left stereo field LB over the right stereo field RB on the projection surface PF.

When projecting onto the projection surface PF1, the right field RB and the left field LB can be adjusted separately. If the projection surface PF2 is projected, then only the left field LB can be adjusted. Only the left field LB is moved, the right field RB is projected directly through the semi-transparent mirror S2. For the right field RB, the semi-transparent mirror S2 functions as a transparent medium and for the right field RB as a reflector, both fields RB, LB are each reflected once, so that a mirror-inverted image results, which can be relativized by software or hardware.

The beam path is illustrated for the left field LB with solid lines and for the right field with dashed lines.

In this embodiment according to FIG. 2, the right field RB is projected directly and the left field is reflected twice, so that the projected images do not appear mirror-inverted on the projection surface PF, but appear in real representation.

A prerequisite for using this variant of the embodiment of the attachment is that the light of the left and right fields LB and RB are polarized perpendicular to one another. There are two options here, depending on whether the projector emits linearly polarized light or not. In the first case, the polarization plane of the light has to be rotated by 90 °. This can be achieved, for example, with a delay film or retarder R (bold, dashed), which should have the position as indicated in FIG. 1. These retarders R are almost transparent, so that almost no light loss would result from additional polarization.

Various other known elements such as λ / 2 plates can also be used as optical components for rotating the polarization plane by 90 °. In the second case, polarizers P1 and P2 (bold, dotted) would have to be inserted between the projection lens and the attachment in such a way that the left and right fields LB and RB are polarized at 90 ° to one another.

The retarder R can also be arranged at the position P1 or P2. If the mirror S2 is shifted to the right by one field width, then a totally reflecting mirror should be used instead of the semi-transparent mirror S2. The path for both drawing files is the same length. Except for unavoidable optical losses at the interfaces / reflectors, the full brightness is used. There is no color dispersion through semi-transparent mirrors, the partial images can be adjusted independently.

This embodiment according to FIG. 2 permits a more compact design of the attachment compared to the embodiment according to FIG. 1, since shorter paths and smaller lenses are used.

Another embodiment of the attachment according to the invention is shown in Fig. 3. In this embodiment, unpolarized light or light with a defined position of the vibration plane is a prerequisite for use.

The set-up consists of a surface mirror S that can be rotated a few degrees perpendicular to the projection plane and a beam splitter B that can be moved in the same way. The beam paths for the left field LB (continuous, thin line) and the right field RB (thin, dashed line) are analogous to Embodiment according to FIG. 2. In addition, the polarization planes for the rays of the two fields after exiting beam splitter B are illustrated in FIG. 3 by oblique or straight cross lines.

This variant requires that the projector either emits unpolarized light or linearly polarized light such that all colors of the visible spectrum are in one and the same plane of polarization and that this plane has a defined angle to the beam splitter.

In linearly polarized light projectors, a retarder R is arranged between the lens output for the left field Lb and the mirror S or lens output for the right field RB and the beam splitter B or mirror S and beam splitter.

When projecting onto the projection surface PF1, the beam splitter B acts as a transparent, polarizing medium for the left field LB and as a reflecting, polarizing medium for the right field RB. The planes of polarization of both fields RB, LB are perpendicular to each other. Analogously to the embodiment according to FIG. 2, both fields are reflected here once, so that a mirror-inverted 3D image is produced.

When projected onto the projection surface PF2, the beam splitter B acts as a reflecting, polarizing medium for the left field LB and as a transparent, polarizing medium for the right field RB. Here, too, the polarization planes of the two images are perpendicular to each other, but in the opposite way. In this case, the left field LB is reflected twice, so that no mirror image is created.

If a projector emits linearly polarized light, but the polarization plane is not formed at the correct angle, then by using a flat, non-structured LC cell, the polarization plane can be rotated by adjusting the amplitude of the AC voltage applied to the LC cell be that it lies in the required level.

The construction of the attachment in the embodiment according to FIG. 4 consists of the same components as the embodiment according to FIG. 3, but positioned differently. Here, too, the beam profiles for the right field RB (dashed, thin) and for the left field LB (continuous, thin) and their polarization directions after emerging from the beam splitter B are illustrated analogously to the embodiment according to FIG. 3. In the central area, where both fields overlap on the projection surface PF in area 2, the spatial image is created. Both fields are reflected once, so that a mirror-inverted 3D image is created. The requirements for the light that the projector emits are the same as in the embodiment of FIG. 3.

A variant of this embodiment shown in FIG. 4 could be that the mirror S is arranged parallel downwards, that is, under the lower left corner of the beam splitter B, and that a retarder R is arranged when the projector 1 is linear emits polarized light and the polar plane is at the right angle to the beam splitter B.

In principle, it applies to all the variants listed here that the projection surface or projection wall can be a reflective or a transmissive medium, so that they can be used for front and rear projections. The prerequisite for this is that these media do not have a depolarizing effect for the entire spectrum of visible light or that they change the polarization level at individual frequencies.

Furthermore, all of the variants listed here can also be applied to multi-beam projection systems in order to generate a three-dimensional image.

In the embodiment according to FIG. 5, the attachment consists of one unit 11, 21, 31, 41; 12, 22, 32, 42 for generating linearly polarized light for the left and right fields and a unit 21, 22 for superimposing the two fields. To avoid imaging errors, the path lengths for both fields are of the same length. Before the Mixing, the polarization plane of the one partial image is rotated relative to the polarization plane of the second partial image such that, after mixing, the one partial image has a polarization plane rotated by 90 ° to the other partial image.

The unit 11, 21, 31, 41; 12, 22, 32, 42 for generating the linearly polarized light works in such a way that, regardless of the polarization state of the incident light, linearly polarized light of a defined position of the polarization plane emerges at the output. All polarization components of the light in the incident light occur in the same ratio as in the incident light (ie, if 30% of the light is horizontally polarized or 70% vertical, then the horizontally polarized component bears 30% and the vertically polarized component 70%. to the intensity of the outgoing light). This means that projectors that emit different polarized light depending on the wavelength can also be used (e.g. typical poly-Si TFT projectors).

A unit for mixing 13, 33, 34, 35 of the differently polarized partial images is arranged in such a way that the two partial images polarized perpendicular to one another are blended exactly one above the other (with the same parallax angles), so that no further adjustment work is necessary. The attachment only has to be aligned parallel to the center beam and horizontally parallel to the lower or upper image edge of the light emitted by the projector and approximately in the center of the lens.

The unit for generating the polarized light consists of a beam splitter 11 to 13, which divides the incident light into its two components. In the further beam path of the two partial beams, mirrors and / or prisms 21, 22 are arranged such that they are blended again one above the other, the path lengths of both partial beams being of equal length. An optical component, for example a λ / 2 plate 41, 42, is arranged in the beam path of a partial beam for rotating the polarization plane by 90 °, so that after the alignment Blending of the two partial beams of linearly polarized light is available, parts being retained relatively. If the component for rotating the polarization plane in the otherwise symmetrically constructed unit for the second partial image is arranged in the other partial beam, the polarization plane of the outgoing light is rotated by 90 ° to that of the first partial image.

In the further beam path of the partial images, mirrors 31 to 35 are arranged in such a way that they fall into an expensive beam at an angle of 90 °, which is arranged in such a way that the two partial images are blended exactly one above the other, which is possible because a) the Path length of the beam paths of the two partial images is the same and b) the polarization plane of the partial images is rotated by 90 ° to one another.

In one embodiment variant (not shown), the unit for rotating the polarization planes can also be omitted.

As shown in FIG. 6, the mixing unit can be formed, for example, from a semi-transparent mirror 211, a mirror 212 and an absorbent surface 213. An advantage over the known prior art is the fact that here it is not a prerequisite that, as in other mixing methods, both partial beams enter the common output beam in equal parts.

REFERENCE NUMBERS

1 projector

2 area

3 retardation filters

4 diaphragm 1 beam splitter 2 beam splitter 3 beam splitter 1 mirror / prisms 2 mirrors / prisms 1-35 mirrors 1.42 λ / 2 plate

211 Semi-transparent mirror

212 mirrors

213 Absorbent surface

PF projection area

LB left field

RB right field

S mirror

B beam splitter (beam splitter)

Claims

claims

1.Attachment for a linearly polarized light-emitting video projector, in the beam of which a left and a right stereo field are arranged spatially next to each other, for 3-D projection of stereo images on a projection surface on which the projection planes are largely retained for viewing with polarization glasses, the attachment consisting of at least two rotatably arranged mirrors (S) and a filter with a retardation film (3) for rotating the direction of polarization of the light by 90 °, and the retardation filter (3) and the two mirrors (S) to one another are adjusted so that only the light beam of one of the two stereo fields is rotated in its polarization direction by the retardation filter (3) and both stereo fields are projected onto one another on the projection surface (PF).

2. Attachment according to claim 1, characterized in that an aperture (4) is attached to the attachment in such a way that disturbing reflections caused by scattered light from the attachment on the edges of the projection surface (PF) are prevented.

3. Attachment according to claim 1, characterized in that the mirror (S2) attached in the region of the lens center is semipermeable.

4. Attachment for an unpolarized light and / or linearly polarized light emitting single-beam video projector, in the beam of which a left and a right stereo field are arranged spatially next to each other for 3-D projection of stereo images on a projection surface, in which the polarization planes largely retained, for viewing with polarized glasses, being the attachment is formed from at least one movable mirror (S) for one stereo field and from a beam splitter (B) such as Nicols prism for the other stereo field.

5. An attachment according to claim 4, characterized in that the beam splitter (B) covers one of the two stereo fields and the mirror (S) covers the other stereo field.

6. The attachment according to claim 4, characterized in that the beam controller (B) records both stereo fields and that the mirror (S) is arranged in such a way that the field desired for imaging is reflected on the projection surface.

7. attachment according to claims 4 to 6, characterized in that a diaphragm (4) is attached to the attachment in such a way that disturbing reflections caused by scattered light from the attachment on the edges of the projection surface (PF) are prevented.

8. Attachment for a light-emitting single-beam

Video projector, in the beam of which a left and a right stereo field are arranged spatially next to each other, for 3-D projection on a projection surface for viewing with polarized glasses, the attachment consisting of one unit (11, 21, 31, 41; 12 , 22, 32, 42) for generating linearly polarized light for the left and the right field, a unit (21, 22) for superimposing the two fields, from an optical component for rotating the polarization plane by 90 °, from a unit ( 211, 212, 213) is formed for mixing the two fields polarized perpendicular to one another.

9. attachment according to claim 8, characterized in that one beam splitter for each stereo field, one mirror for each stereo field, one retardation filter (λ / 2- Plate) for each half of each stereo field, one optical element per stereo field, which superimposes two parallel beam paths to form a beam output, further mirrors and another beam splitter, which together form the two stereo fields with their complementary polarization polarizations. mix planes into a stereo-coded output image, are provided, the optical elements being arranged with respect to one another such that the polarization planes of each stereo field are separated, one of the two separated components is rotated, the components are mixed to form a parallel beam path in such a way that for Each stereo field creates an image with a polarization plane rotated by 90 °, which are then mixed into a common image via the further beam control.

10. Attachment according to claims 8 and 9, characterized in that the mixing unit is formed from a semi-transparent mirror (211), a mirror (212) and an absorbent surface (213).

11. Attachment according to claims 8 to 10, characterized in that an aperture (4) is attached to the attachment in such a way that disturbing reflections caused by scattered light from the attachment on the edges of the projection surface (PF) are prevented.