DE10359992A1 - Multicolor image projection apparatus, has color management system arranged between light source and light modulators and color management system arranged after light modulators - Google Patents

Abstract

A color management system (9) is arranged between a light source (1) which emits multicolor light and multiple light modulators (3,4,5), each light modulator being impinged upon by light of different colors, and generating a respective color sub-image. A second color management system (13) and intermediate focussing lens (15) are provided after the light modulators. The second color management system superposes color sub-images so that an intermediate image is formed in an intermediate image plane which is projected onto a projection surface.

Description

The The invention relates to an arrangement for projecting a multicolor image on a projection surface, with a light source unit, the multicolored light emits, several light modulators, respectively be charged with light of a different color and that on it to model falling light, in each case one color partial image of the multicolor Create image, as well as with a projection optics, the color sub-images in overlaying Way onto the projection screen projected to produce the multicolored image.

If (such as LCoS modulators = L iquid C Ristal o n S ilicon modulators) are used as reflective light modulators, polarisationssentive light modulators, it is difficult to achieve a high system contrast. For a high system contrast, it is necessary to position the necessary polarization beam splitters as directly as possible in front of the corresponding light modulator, the number of polarization beam splitters thus being greater than or at least equal to the number of light modulators. If glass cubes with a dielectric splitter layer are used as the polarization beam splitter, this leads to high costs, since such polarization beam splitters are very expensive. Furthermore, there is the difficulty of suppressing the unwanted stress birefringence. The difficulty of stress birefringence can be solved with so-called lattice polarizers. However, there still remains the difficulty of very large cutting widths of the projection optics, which makes the projection optics complex and expensive. Also, the color correction is very difficult for such long cutting distances.

One approach to get to grips with the difficulties associated with the long focal length of the projection optics in the DE 101 27 621 A1 and DE 101 27 620 A1 described in each case an intermediate imaging system between the light modulators on the one hand and the projection optics on the other hand is provided, which images the light modulators in an intermediate image plane, wherein the projection optics then projects the image in the intermediate image plane on the projection surface. A disadvantage of the projection systems described in these publications, however, is that the same color management system is used for the color separation and the color recombination and that this is arranged between the polarization beam splitter and the light modulators. For such a construction, it is extremely difficult to develop a color management system that produces sufficiently low edge shift and no unwanted depolarization.

outgoing It is the object of the invention to provide an arrangement for projecting to provide a multicolor image on a projection surface, with the a multicolored image with excellent quality can be projected.

According to the invention Task solved by an arrangement for projecting a multicolor image onto a projection, with a light source unit that emits multicolored light, several Light modulators, a first color management system that intervenes the light source unit on the one hand and the light modulators on the other hand is and that applies light of a different color to each light modulator, wherein the light modulators modulate the light incident on them to each to produce a color subframe of the multicolor image, further with a second color management system that is different from the first and an intermediate imaging optics, both the light modulators are downstream, wherein the second color management system, the color sub-images so superimposed and the intermediate imaging optics the color sub-images so in an intermediate image plane depicts that in the intermediate image plane is a multicolored intermediate image is generated the downstream of one of the intermediate image plane projection optics on the projection screen is projected.

By the provision of two color management systems, the first of which is used to illuminate the light modulators and the second to together the color subpictures, can the color management systems are each optimized for their task, so that projected image has a high quality.

In In a preferred development, the light modulators are reflective Light modulators formed, in particular, they are also polarization-sensitive could be (e.g., LCoS light modulators). In this case, due to the provision of the two color management systems the advantage that the necessary polarization beam splitter between the light modulators arranged on the one hand and the two color management systems on the other can be. The polarization beam splitters can thus possible be placed directly in front of the light modulators, creating an excellent Contrast in the image production is achieved, resulting in a qualitative high-quality projected image leads.

The light modulators have an imaging region, for example rectangular, with a plurality of independently controllable pixels, from which the incident light is emitted in a modulated manner (eg with respect to an out case angle or its polarization state). When the light is modulated with respect to its polarization state, polarization-sensitive light modulators are used here. The light modulators or the pixels of the imaging areas can be switched into two states at least in each case, the light emitted by pixels in the first state having a first modulation state, which is used for bright-switched pixels (ON light), and that of FIG light emitted in the second state has a second modulation state which is used for dark-connected pixels (OFF light), so that images (or color sub-images) are generated on the light modulators or their imaging regions in this sense. Alternatively, the second state of the pixels may cause the light to be absorbed and no longer emitted or the light to be put in such a state that it does not reach the projection surface.

If as light modulators reflective, polarization-sensitive light modulators For example, it is preferable to use a polarization beam splitter before each light modulator to arrange, which causes the corresponding light modulator with light of a predetermined polarization state is illuminated, the polarization beam splitter also as analyzers used for it be to the light reflected from the light modulator, the ON light of to disconnect the OFF light. This will be an excellent contrast allows for image projection, as the number of elements between the polarization beam splitters and the light modulators can be minimized and thus also the adverse depolarizing effect of such elements. The polarization beam splitter can reflect the light to illuminate the light modulators and transmit the ON light or transmit the light for illumination and reflect the ON light.

In particular, as a polarization beam splitter, a grating polarizer, such as a metal grid polarizer, as used for example in the US 6,243,199 B1 is described.

In a preferred embodiment of the projection arrangement according to the invention is the second color management system between the intermediate imaging optics on the one hand and the light modulators on the other hand arranged. In order to will it be possible the intermediate imaging optics possible small and compact form, since the color sub-images of the light modulators already superimposed by means of the second color management system.

alternative it is natural also possible, the second color management system between the intermediate imaging optics and the intermediate image plane to arrange. This leads to the advantage that the intermediate imaging optics may have several partial optics, each for the corresponding Color channel (i.e., the corresponding color sub-image) can be optimized. This then leads to a very high quality image projection.

Further it is also possible that this second color management system partly between the intermediate imaging optics and the intermediate image plane and partly between the intermediate imaging optics on the one hand and the light modulators on the other hand is arranged. This is especially for Suitable applications in which at least three light modulators (preferred more than three light modulators) can be used.

The Intermediate imaging optics can be designed as a 1: 1 imaging optics be. this leads to to the advantage that the Intermediate image has the same size like the color sub-images set on the light modulators, whereby the lens diameter of the lenses of the projection optics kept small can be.

Especially the intermediate imaging optics can be symmetrical (relative to a Point on the optical axis of the intermediate imaging optics; prefers exactly in the middle between the light modulators on the one hand and the intermediate image plane on the other hand), on the one hand their manufacture is simplified and on the other hand by the Between imaging optics generated aberrations kept very small can be (in the optimal case, they are practically zero).

The Of course, intermediate imaging optics can also be used be designed so that the imaging areas of the light modulators reduced or enlarged in the intermediate image plane are displayed. If they are shown scaled down can, can the optical elements of the projection optics will be smaller, thereby Weight savings are achieved and the production of the projection optics is relieved.

Especially can the intermediate imaging optics as folded optics (unique or repeated folding) may be formed. This makes it possible that the projection arrangement overall extremely compact can be trained.

The intermediate imaging optic for folding preferably has a curved mirror. The remaining elements of the intermediate imaging optics can be designed so that they are traversed twice due to the folding of the beam path by means of the mirror in each image, whereby the number of required optical elements can be significantly reduced, resulting in a lighter and cheaper to produce Zwischenabbil tion optics leads.

In a preferred embodiment of the arrangement according to the invention is the intermediate imaging optics as catadioptic optics (an optic, the at least one imaging mirror and at least one imaging Lens included) educated. With such an appearance can be particularly good Image properties in small dimensions with few optical elements realize.

Further can the projection arrangement according to the invention still have a control unit, the light modulators on the basis of predetermined image data so controls that the desired Color partial images can be generated by means of the light modulators.

Of Further, it is of course possible in the inventive arrangement, by further polarizers (pre-polarizers and / or clean-up polarizers) as well as by retarder to achieve a contrast increase. Also is it is possible to arrange a field stop in the intermediate image plane whose aperture exactly corresponds to the imaged intermediate image, so that a brightening outside of the projected image can be safely avoided.

Farther Is it possible, that between the intermediate imaging optics and the projection optics one more or several more deflections are performed, for example to realize a very compact projection arrangement.

The Light source unit can be a single light source, the multicolor Emits light, and preferably also a lighting optics for Have beam cross-sectional shaping. In this case, the first provides Color management system for it, that out the multicolored light (or multicolor light beam) of the light source the corresponding Colors (for example red, green and blue) and to the corresponding light modulators be steered.

alternative Is it possible, that the Light source unit has a plurality of light sources, in particular LED light sources can be used. In this case exists the first color management system is to arrange the light sources so and Optionally necessary optical elements provided so that the light the corresponding light sources falls on the associated light modulators.

at the use of polarization-sensitive light modulators can the light source unit is a system for polarization recovery have, if the light source or the light sources themselves not only light of the desired Output polarization state.

With the projection arrangement according to the invention is due to the decoupling of the imaging (due to the Zwischenabbildungsoptik) and the image projection by means of the projection optics advantageous achieved that the same structure for the image production for different projection systems can be used. Thus, front and rear projection equipment realized become. It only has to be the Projection optics according to the respective front or rear projection be formed because the optical interface of the intermediate image plane is present.

The The invention will be described by way of example with reference to the drawings even closer explained. It demonstrate:

1 a schematic front view of an embodiment of the projection assembly according to the invention;

2 a schematic side view of the projection arrangement of 1 , and

3 a top view of the X-cube of 1 ,

As can be seen in particular 1 The projection arrangement for projecting a multicolor image onto a projection surface comprises a light source unit 1 (eg a halogen or arc lamp), which emits multicolored light (white light), then through a lighting optics 2 running, for example, the light of the light source unit 1 converted into a desired beam cross section.

The projection assembly further includes three light modulators 3 . 4 . 5 , for the colors red, green, blue, as well as three polarization beam splitters 6 . 7 and B. Like in the 1 and 2 is shown, is in each case one of the polarization beam splitter 6 - 8th directly in front of one of the light modulators 3 - 5 arranged.

Furthermore, there are two color dividers 9 . 10 as well as two deflecting mirrors 11 and 12 arranged such that the white light coming from the illumination optics 2 comes on the first color divider 9 meets, causing the blue light, in 1 seen, is reflected upward and the red and green light is transmitted. The red and green light hits the second color divider 10 who in 1 through the deflection mirror 12 is concealed, with the second color divider 10 the green light reflects (in 1 seen: out of the drawing plane, in 2 seen: to the right) and the green light transmitted. For better clarity of the representations are in 2 (which is a side view from the left of 1 is) the light source unit 1 , the lighting optics 2 , the first color divider 9 , the polarization beam splitter 7 as well as the light modulator 4 not shown. The transmitted green light hits, as in 1 it can be seen on the first deflection mirror 11 and will thus, in 1 seen, reflected upwards. In the same way, the red light by means of the second deflection mirror 12 deflected so that it goes up and on the first polarization beam splitter 6 ( 2 ) meets.

The polarization beam splitter 6 - 8th are formed as Metallgitterpolarisatoren, each reflecting the proportion of light, which is in the first polarization state (s-polarization state), and the proportion of the light in the second polarization state (p-polarization state) transmit, so that the light modulators 3 . 4 and 5 each illuminated with s-polarized red, blue or green light. The light modulators 3 - 5 , which are here designed as LCoS modulators, reflect the light incident on them, rotating the polarization state of the reflected light for bright pixels to be switched by 90 ° so that this reflected light has the p-polarization state and of the polarization beam splitters 6 - 8th is transmitted. In the light for dark pixels to be switched, no change in the polarization state is performed, so that this through the polarization beam splitter 6 - 8th be reflected back to the light source unit. The polarization beam splitter 6 - 8th thus also serve as analyzers for the separation of ON and OFF light.

The color dividers 9 and 10 form here a first color management system that between the light source unit 1 on the one hand and the light modulators 3 to 5 is arranged and ensures that the light modulators 3 to 5 each be acted upon with different colored light.

That of the light modulators 3 to 5 reflected and from the polarization beam splitter 6 to 8th transmitted light is transmitted by means of a second color management system 13 merged into a common multicolor beam. The second color management system is designed as a so-called X-cube, which has two color layers F1 and F2 intersecting at an angle of 90 ° with respect to the directions of incidence of the polarization beam splitters 6 to 8th Transmitted beams are each inclined by 45 °, as shown 3 it can be seen that the X-cube in plan view together with the light modulators 3 - 5 and the polarization beam splitters 6 - 8th shows, with only the beam paths of the ON light are indicated. The reflection and transmission properties of the two color layers F1, F2 are chosen so that thereby a superposition of the three color sub-beams to a common color bundle 14 he follows.

The common color bundle 14 goes through an intermediate imaging optics 15 ( 2 ), which is a lens optic 16 and a mirror 17 comprises, which is preferably curved, and reaches an intermediate image plane ZE. The intermediate imaging optics 15 is formed so that in the intermediate image plane ZE an intermediate image 17 the individual imaging areas of the light modulators 3 to 5 is generated and thus a multicolor intermediate image of the image to be projected. The intermediate image plane ZE or the intermediate image 17 is a projection optics 18 subordinate to the intermediate image 17 then on the projection screen 19 projected. The projection optics 18 as well as the projection surface 19 are for simplistic representation in 1 not shown.

In the projection arrangement according to the invention is advantageously achieved by the provision of the first and second color management system that the polarization beam splitter 6 to 8th directly in front of the light modulators 3 to 5 can be arranged so that the unwanted depolarizing effects can be minimized, since the number of optical components between the polarization beam splitters 6 - 8th and the light modulators 3 - 5 can be minimized, in particular, no optical components can be present in between more. The polarization beam splitter 6 - 8th are thus between the first color management system 9 . 10 and the corresponding light modulators 3 - 5 as well as between the second color management system 13 and the corresponding light modulators 3 - 5 ,

Of course, the light source unit 1 also be designed (not shown) that it has a plurality of light sources (eg LED), which emit light each with a different color. In this case, the first color management system is to arrange the light sources and optionally provide optical elements so that the light of the corresponding light sources on the associated light modulators 3 - 5 falls.

Claims (11)

Arrangement for projecting a multicolored image onto a projection surface, having a light source unit ( 1 ), which emits multicolored light, several light modulators ( 3 . 4 . 5 ), a first color management system ( 9 . 10 ) located between the light source unit ( 1 ) on the one hand and the light modulators ( 3 - 5 on the other hand, and that each light modulator ( 3 - 5 ) is exposed to light of a different color, the light modulators ( 3 - 5 ) modulate the light incident on them to produce one color sub-image of the multicolor image, and a second color management system different from the first ( 13 ) and an intermediate imaging optics ( 15 ), whereby both the second color management system ( 13 ) as well as the intermediate imaging optics ( 15 ) the light modulators ( 3 - 5 ) and the second color management system ( 13 ) superimposed the color sub-images and the intermediate imaging optics ( 15 ) images the color sub-images into an intermediate image plane such that in the intermediate image plane a multicolored intermediate image ( 17 ), the projection optics arranged downstream of one of the intermediate image planes ( 18 ) on the projection surface ( 19 ) is projected. Arrangement according to Claim 1, in which the light modulators ( 3 - 5 ) as reflective light modulators ( 3 - 5 ) are formed. Arrangement according to one of the above claims, in which the light modulators ( 3 - 5 ) are formed as polarization-sensitive light modulators. Arrangement according to Claim 1, in which the light modulators ( 3 - 5 ) are designed as reflective, polarization-sensitive light modulators and in front of each light modulator ( 3 - 5 ) in each case a polarization beam splitter ( 6 . 7 . 8th ) arranged to illuminate the corresponding light modulator ( 3 - 5 ), the polarization beam splitters ( 6 - 8th ) can also be used as analyzers to separate the ON light from the OFF light. Arrangement according to Claim 4, in which the polarization beam splitters ( 6 - 8th ) are formed as Gitterpolarisatoren. Arrangement according to one of the preceding claims, in which the second color management system ( 13 ) between the intermediate imaging optics ( 15 ) on the one hand and the light modulators ( 3 - 5 ) is arranged on the other hand. Arrangement according to one of Claims 1 to 5, in which the second color management system ( 13 ) between the intermediate imaging optics ( 15 ) and the intermediate image plane (ZE) is arranged. Arrangement according to one of Claims 1 to 5, in which the second color management system ( 13 ) partially between the intermediate imaging optics ( 15 ) and the intermediate image plane (ZE) as well as partly between the intermediate imaging optics ( 15 ) on the one hand and the light modulators ( 3 - 5 ) on the other hand. Arrangement according to one of the above claims, in which the intermediate imaging optics ( 15 ) is designed as a 1: 1 imaging optics. Arrangement according to one of the above claims, in which the intermediate imaging optics ( 15 ) is formed as a folded optic. Arrangement according to one of the above claims, in which the intermediate imaging optics ( 15 ) at least one mirror ( 17 ), which is preferably curved, has.