WO2005069073A1

WO2005069073A1 - Image projection apparatus

Info

Publication number: WO2005069073A1
Application number: PCT/IB2005/050039
Authority: WO
Inventors: Roman Prager
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2004-01-09
Filing date: 2005-01-05
Publication date: 2005-07-28

Abstract

In an image projection apparatus (1) with an electro-optical imaging apparatus (2) and with an optical image projection apparatus (3) for projecting images on a projection screen (7) the image projection apparatus (3) is allocated a selectively activable image rotating element (5) for selective rotation of at least one of the images projected on the projection screen.

Description

Image projection apparatus

The invention relates to an image projection apparatus with electro-optical imaging means and with optical image projection means for projection of images on a projection screen. Such image projection apparatus find an increasingly frequent application, for example for home cinema or for computerized presentations. In the context of imaging means, for example LCD, DLP and similar techniques are used, and the image format is therein - according to usual video techniques - specified at a width- to- height ratio of 4:3 or 16:9. These image formats, however, entail that the vertical resolution is substantially lower than the horizontal resolution. These image formats, corresponding to the standard of video films, thus result with other imaging, approximately on the basis of photos, in the disadvantage that the representation of upright format images is qualitatively noticeably inferior to that of landscape format images, wherein under normal conditions, the upright format images have to be converted in the electronic way and their resolution has to be reduced.

An image projection apparatus is known, from patent document EP 1 280 002 A, wherein a projector with electro-optical imaging means and with associated optical image projection means is arranged at the rear side of a projection screen. In order to enable the intended space saving arrangement of the projector just behind the projection screen, the image projection means have two mirrors, which are permanently arranged at a specific angle to each other and to the optical axis of the imaging means and to the projection screen, wherein starting from a projection lens of the imaging means, up to the projection screen there is a fixed rotating of the projected images by 90°. The above mentioned disadvantage results here as well, that in case of designing the image projection apparatus for a 4:3 or 16:9 image format for the projection of upright format images in comparison with the landscape format images, quality losses have to be accepted due to the reduced resolution. It is therefore an object of the invention to find a remedy and to arrange for an image projection apparatus according to the opening paragraph, with which vertical and landscape format images can be reproduced with equally good resolution and quality, wherein the means used for this should be simple and price worthy in manufacture as well as without problems in operation. In general image position changes, particularly image position corrections should preferably be effected in a simple way. To achieve this object, features according to a main aspect of the invention are provided in an image projection apparatus, so that the image projection apparatus can be characterized in the following manner: Image projection apparatus with electro-optical imaging means and with optical image projection means for projecting images on a projection screen, wherein a selectively activable image rotating element for selective rotation of an image projected on the image projection screen is assigned to the image projection means. With the present image projection apparatus desired rotations of images, which are to be projected on the projection screen, can be arranged depending on the arrangement and the structure of the image rotating element. In this way especially with image projection apparatus, with 4:3 or 16:9 image format, upright format images can be generated as landscape format images with a high resolution and then on the basis of the image rotation it can be reproduced in the upright format with the help of the image rotating element on the projection screen. Depending on the arrangement of the image projection apparatus and its electro-optical imaging means, the image rotation element can then be manually activated if individual images are reproduced selectively, or else an automatic activation can be provided, for example an activation resulting from an image analysis or preprogrammed in a computing area. The image projection apparatus according to the invention can, however, also be used for other purposes with a corresponding arrangement of the image rotating element, where optional image rotating angles are desired, especially when particular images, which are taken photographically, should be reproduced over the image projection apparatus, wherein with individual images there are undesired inclined positions due to amateurish photos, which amateurish photos can now be corrected by changing the image direction respectively orientation with the help of the image rotating element provided according to the invention. Another application is conceivable for example with presentation systems, when particular images or image sequences, especially automatic and pre-programmed are projected in different positions on the wall or on other projection surfaces, wherein the images could under circumstances, comprise only certain color combinations in different geometrical patterns. Inherently, the generated light beam can in normal cases go round the image rotating element and consequently cannot collaborate with the image rotating element and can if necessary collaborate with the generated light beam through a deflection of the generated light beam caused by an electrical signal. Preferably, however, the image rotating element is coupled to electromagnetic driving means for the purpose of direct selective activation, the image rotating element being arranged for example pivotably or shiftably. The electromagnetical driving means are advantageously connected to control means, to preferably bring about the desired movement of the image rotating element for rotation of the image to be projected, preferably manually for example by feeding in with keys or knobs and /or sliders. The control means can also be connected to a processor or computer, to generate the desired image rotations in accordance with a pre-programming. Another specially preferred alternative comprises connecting the control means directly with the electro-optical imaging means, wherein detector means are placed in the optical imaging means, in order to automatically recognize landscape and upright, to say portrait, formats in the course of image generation or to derive the desired control information based on information embedded in the image data like character bits or image file-names implemented through simple coding. The electromechanical driving means can be formed then through a motor with an output gear for rotating the image rotating element or for displacing the image rotating element. The image rotating element can be structured in an inherently conventional way. In an advantageous way the image rotating element comprises many mirrors arranged inclined or slantingly respectively tilted to each other or a dove prism or a K-mirror or a Pechan-prism. The image rotating element is equipped, in case only the reproduction of upright and landscape images with equally good resolution is desired, in a simple and consequently advantageous way only for rotating the individual images by 90° or 270° at a time. The optical image projecting means often embody an objective, wherein then the image rotating element can be located before the objective or after the objective depending upon the type of focusing and the space ratios. An additional fitting of image projection apparatus with an image rotating element will then often be easier to manage, when the image rotating element is set before the objective, thus is finally located in the radiating direction after the objective. However, with newly conceived image projection apparatus, the image rotating element is located within the housing of the image projection apparatus and thus still located in the path of the beam before the objective, for reasons of dust protection and safety. The invention is subsequently further elucidated with reference to the embodiments, which are represented in the Figures and to which the invention should not be limited.

In the drawings: Fig.l is a top view diagram of an image projection apparatus according to the invention with an image rotating element in an inactive position. Fig. 2 shows the image projection apparatus according to Fig. 1 in a comparable top view, now however with the image rotating element in a displaced position. Fig. 3 illustrates in a diagrammatic representation a modified embodiment of the image projection apparatus according to the invention, with an image rotating element rotatably arranged before the objective, which image rotating element is in an inactive position. Fig. 4 illustrates in a diagrammatic representation (comparable to Fig. 3) the image projection apparatus according to Fig. 3, wherein now however the image rotating element is rotated into an active position, in order to produce a rotation of the image to be projected. Fig. 5 diagrammatically illustrates in a block circuit diagram an image projection apparatus according to the invention with a fitted image rotating element and the related driving and control means.

In the Figs. 1 and 2 an image projection apparatus 1 is diagrammatically shown in top view, wherein however electro-optical imaging means 2 as well as optical image projection means 3 are illustrated with an objective 3'. The electro-optical imaging means 2 and the optical image projection means 3 therein define an optical path or beam whose optical axis and /or optical path 4 is indicated with a dash-and-dot line. According to Fig. 1 there is a selectively activable image rotating element 5 outside the optical path 4, i.e. this image rotating element 5 takes its normal position or rest position. The optical image rotating element 5 is adjustable for its selective activation according to a double arrow 6 in Fig. 1. In Fig. 2 the optical image rotating element 5 is represented in its relocated active image rotating position in the optical path 4. The optical image rotating element 5 is in the present case firmly fixed for rotating an image by 90° (or 270°), so that in the active position illustrated in Fig. 2, the image 8 projected on a projection screen 7 diagrammatically indicated only in Fig. 1 occupies a position rotated through a right angle compared to the position in Fig. 1, wherein a horizontal double arrow in Fig. 1, representing the image 8, can henceforth be shown normally to the drawing plane that is, as a slot. In this way it is possible for example under normal circumstances, that is in the setting of the apparatus according to Fig. 1 to project images in landscape format of 4:3 or 16:9 as is common in video technology; when images are to be projected in upright or portrait format then these images are nevertheless generated in a landscape format in the electro-optical imaging means 2 and delivered in the direction of the optical image projection means 3, however then the optical image rotation element 5 is brought into the optical path 4, to rotate the image and thus to project on the projection screen 7 in the required upright format representation. As a result, such upright format images can be reproduced finally in vertical direction with the high horizontal resolution as they are originally generated in landscape format in the electro-optical imaging means 2. The optical image rotating element 5 can be arranged, according to techniques customary per se, with many mirrors positioned inclined to each other, it can be formed by a dove prism, likewise a K-mirror or else a Pechan prism can be used for this purpose. These image rotating elements 5 are themselves well known in optics and the dove prism is referred to only as an example, which dove prism comprises four rectangular areas and two lateral trapezium-shaped areas, wherein a beam of light is refracted twice and reflected once in the prism. With a rotation of the dove prism by an angle the finally projected image is rotated by an angle 2 vis-a-vis the original position. This similarly holds for the Pechan prism, which comprises two prism components separated from each other by an air gap. Finally, a K- mirror is, as known, constructed with three individual mirrors, which rotate an image round an axis parallel to the incident beam of light. Thus, if in the image projection apparatus 1 according to Figs. 1 and 2 for example a dove prism, a Pechan prism or a K-mirror is used as an optical image rotating element 5, this image rotating element 5 should itself be rotated by 45° vis-a-vis its customary position, if a 90° rotation of the image is to be produced and in this 45° position according to the double-headed arrow 6 in Fig. 1 the element is moved into the optical path 4 and moved out of this optical path 4 again. From the Figs. 3 and 4 it is obvious that the optical image rotation element 5, instead of being subject to a straight displacement, for its selective activation can also be rotated around its axis, which axis especially coincides with the optical path 4 (refer Figs. 1 and 2). This rotation takes place for example in the case of a dove prism or Pechan prism by an angle of 45°, in order to obtain a rotation of the projected image 8 from the starting position according to Fig. 3 into a position according to Fig. 4 rotated by 90° in contrast. From the diagrammatic representations in Figs. 3 and 4 it is further obvious that in an additional modification of the embodiment according to Figs. 1 and 2 the actual optical image projecting means 3, that is the objective 3' and the optical image rotating element 5 are arranged in a relatively interchangeable position to each other that is that according to Figs. 3 and 4 the image rotating element 5 is located in the path of the beam (optical path 4) after the objective 3' of the image projection apparatus 1. From this it is obvious that conventional image projection apparatus 1 in hindsight can therefore subsequently be equipped without any problems by additional attachment of an image rotating element 5 (understood with corresponding bearing and if necessary with corresponding driving means), wherein if necessary an extended housing, not further shown dn the diagram can be provided for the optical image rotation element 5, which extended housing is connected to the existing housing of the image projection apparatus 1, forming a unit. « In Fig. 5 a block circuit diagram illustrates diagrammatically the electrical/electro-optical structure of an image projection apparatus according to Figs. 1 arid 2 (or else Figs. 3 and 4). The image projection apparatus 1 includes in an inherently conventional way the electro-optical imaging means 2, which electro-optical imaging means 2 comprises electronic image processing means 9 as well as light producing means 10 (for example LCD, DLP and similar light generating units) connected to them in order to generate images each in a 4:3 or 16:9 image format corresponding to the electronic image processing in the image processing means 9 and deliver them over the objective 3' in the direction of the optical path 4. For the power supply of the image processing means 9 and the light producing means 10 a conventional power supply, a battery unit or similar power supply unit 11 can be provided. The electro-optical imaging means 2 can be likewise connected in a conventional way to a PC (Personal Computer) 12, especially to its NGA output 13, further to a CE (Consumer Electronics) unit 14, to a memory card reader 15 and a remote control- receiver 16, in order to receive the corresponding image and control information supplied. In addition to this known equipment, as described so far, the image projection apparatus 1 comprises the already mentioned optical image rotating element 5, which image rotating element 5 can be selectively adjusted with the help of the electro-mechanical driving means 17. The driving means 17 comprise here an electric motor 18 as well as a transmission 19 for a straight displacement of the optical image rotating element 5, as explained above with reference to Figs. 1 and 2. It is observed that the driving means 17 can be arranged for a rotary adjustment of the optical element 5, as described above with reference to Figs. 3 and 4. The motor 18 of the driving means 17 is connected to the control means 20, which control means 20 control the driving means 17 in accordance with an input signal, which input signal is supplied to the control means 20 from the electro-optical means 2. The imaging means 2 comprise the image processing means 9. In the present case, the image processing means 9 comprise detector means 21 for detecting images in landscape format and/or in upright format. In case of images in upright format, these images are as described, nevertheless generated in the landscape format, for which the light emitting means 10 are controlled accordingly and the detector means 21 give a corresponding input signal to the control means 20 for the motor 18, so that the latter selectively displaces and thereby activates the image rotation element 5 via the transmission 19. As a result, the finally projected image 8 is rotated in the desired way, that is by the desired angle, thus in the present case by 90° on the projection screen 7 (refer Fig. 1) not further shown in Fig. 5. In a modification of the embodiment described above, in place of an automatic detection of the respective image direction with the imaging, a lever switch can be provided for the electro-mechanical driving means 17. Further it is possible, for example in the

Personal Computer (PC) 12, if this is provided for supplying the image information, to supply automatically control information for the control means 20 along with the image information, so that the detector means 21 can be made superfluous and the corresponding control information- extraction means are to be provided in the image processing means 9. The same is applicable for the further input units described as examples for supplying image information like the memory card reader 15, the CE unit 14 and the RC receiver 16. Above all with an automatic switching on the basis of the control information supplied along or else on the basis of a data-image analysis of the image information it will be obvious that another image rotation than by 90° and 270° can be provided such as an image rotation by a small angle in the order of some degrees, for example 5° or 10° in the case of a correction of undesired inclined shot images, or an image rotation by any and if necessary constantly changing angles in the case of presentations, for example with advertising events and the like. With a further arrangement of an image rotation element 5 a simple mirror arrangement with a first mirror SI and a second mirror S2 and a third mirror S3 can be provided. The mirror arrangement is therein of the kind, that the mirror SI gives to the second mirror S2, the light beams of the light emitting means 10 given in X-direction deflected by an angle of 90° and the second mirror S2 again delivers these light beams deflected by an angle of 90° to the third mirror S3 and the third mirror S3 again delivers the light beams deflected by an angle of 90° and therein the light beams are again in a direction parallel to the X-direction. This arrangement however additionally produces a mirror- inverted projection of the images on the projection screen 7. In this case it can be provided that the electro-optical imaging means 2 are arranged to generate mirror-inverted images and deliver corresponding image control signals to the light generating means 10, which light generating means 10 subsequently project to the image rotating element 5 normal that is not mirror-inverted images, on the projection screen. In order to cause the image processing means 9 to deliver such image control signals to the light emitting device 10, a corresponding control program can for example be stored in PC 12.

Claims

CLAIMS:

1. An image projection apparatus (1) with electro-optical imaging means (2) and with optical image projecting means (3) for projecting images on a projection screen (7), wherein a selectively activable image rotating element (5) is allocated to the image projecting means (3) for the selective rotation of at least one image projected on the projection screen.

2. An image projection apparatus as claimed in claim 1, wherein the image rotating element (5) is movably supported.

3. An image projection apparatus as claimed in claim 2, wherein the image rotation element (5) is coupled with electro-mechanical driving means (17).

4. An image projection apparatus as claimed in claim 3, wherein the electromechanical driving means(17) are connected to control means(20).

5. An image projection apparatus as claimed in claim 4, wherein the control means(20) are connected to the electro-optical imaging means (2).

6. An image projection apparatus as claimed in claim 2, wherein the image rotating element (5) is arranged pivotably.

7. An image projection apparatus as claimed in claim 2, wherein the image rotating element(5) is arranged displaceably.

8. An image projection apparatus as claimed in claim 1, wherein the image rotating element (5) is arranged with a plurality of slantingly arranged mirrors.

9. An image projection apparatus as claimed in claim 1, wherein the image rotating element (5) is set up for rotating the image by 90° and 270°, respectively .

10. An image projection apparatus as claimed in claim 1, wherein the image rotating element (5) is a Dove-Prism or a K-mirror or a Pechan prism.

11. An image rotating element as claimed in claim 1, wherein the optical image projection means (3) comprise an objective (3') and the image rotation element (5) is arranged before the objective (3').

12. An image projection apparatus as claimed in claim 1, wherein the optical image projecting means (3) comprise an objective (3') and the image rotation element (5) is arranged behind the obj ective.

13. An image projection apparatus as claimed in claim 1, wherein the imaging means (2) are set up for selective generation of mirror-inverted images.

14. An image projection apparatus as claimed in claim 4, wherein the control means (20) are set up for automatic displacement of the image rotation element(5).