COMPACT PORTABLE PROJECTION DISPLAY SYSTEM

FIELD OF THE INVENTION

The invention is generally in the field of projection display systems, and relates to a compact portable projection display system utilizing a frequently used portable electronic device, such as a mobile phone.

BACKGROUND OF THE INVENTION

Image projection display systems are becoming essential parts of a variety of devices such as computers, television sets and cinema systems. Front-only projecting systems are well known in the art as are rear-only projecting systems including televisions with rear projection display for home theatre systems. Similarly, flight simulator systems make use of upright projection display or projection display in other directions.

SUMMARY OF THE INVENTION

There is a need in the art for multi-mode projection display systems, namely systems capable of concurrently or selectively projecting an image onto different projection surfaces, by optical means. Moreover, there is a need in the art in such a multi-mode projection display system that can be incorporated in or used together with

(connectable to) a frequently used portable electronic device of a kind capable of generating information in a digital, video or other picture formats. Such electronic devices include for example, portable digital assistants (PDAs), mobile phones, Laptop computers, portable media player (PMP), or flash memory storage devices, which are often equipped with relatively small built-in LCD panels for picture viewing.

Providing a compact optical projection unit incorporated or used together with in such a portable electronic device would provide a convenient tool for optical projection of digital, video or other visually represented information, generated by the device' electronics onto a projection surface outside the electronic device thus exposing

information to one or several viewers, in dimensions larger than built-in LCD panels of an electronic device. Due to the portability of these electronic devices and variety of subjective preferences for convenient picture viewing demanded by different users, it is necessary to have a flexible system which can adapt to accommodate a plurality of conditions. There is therefore a need for a compact projection display system which provides multiple projection modes which are selected by a user to suit the projection environment. The introduction of extremely small size pocketable projection engines opens the path for a new range of devices that can combine different projection modes to provide the users with flexibility in operating environments and scenarios. Accordingly, the current invention discloses a projection display system formed by a convenient and frequently used portable electronic device carrying or connected to a compact optical projection unit and carrying a deflection unit for deflecting an image created by the projection unit towards one or preferably more than one differently oriented projection surfaces. The optical projection unit includes a spatial light modulator for modulating the digital information to produce an image indicative thereof and directing this image towards externally from the electronic device, at required magnification and viewing distance. The deflection unit includes one or more light deflectors such as prism(s) and/or mirror(s) which is/are displaceable with respect to the optical projection unit, under the user's control, to selectively deflect the image towards the desired projection surface(s) to thereby provide the system operation with multiple projection modes.

The term "projection mode" signifies the direction, magnification and viewing distance of the projected image created by the optical projection unit in accordance with certain digital, video or other visually represented information and preferably also the orientation of the image. The direction of the projected image is determined by the configuration of the adjustable deflection unit(s). The orientation of the projected image is determined by software and/or hardware utility providing image reversal in either the vertical axis or the horizontal axis, image intensity control as well as optional image rotation. A projection mode is selected which best answers the user's requirements given the constraints of the projection environment, such as the orientation of possible projection surfaces, availability of space and the positions of the viewer(s).

As with any portable device, the compact projection display system should preferably provide a projected image of the required dimensions upon a projection

surface located close to the body of the device. Therefore wide angled projection is used to minimize the distance between a light source and the projected image of given dimensions. Wide angle projection display systems provide highly divergent beams directed towards the projection surface. Moreover, in projection display systems with several projection modes, where the projected image is deflected before reaching the projection surface, the highly divergent beam is directed first towards an adjustable deflection unit. Due to the compact nature of the invention there is only a small distance between the exit facet of the wide angled lens, or beam exit point, and the deflection units attached to the device. The combination of large divergence angles and small distances, when a deflection of the image to any projection surface other than that of the direct front projection surface, can result in partial masking of the cross section of a light beam being deflected by the body of the electronic device. The current invention solves this problem by using the so-called "off-axis" projection to direct the divergent beam away from the device body, in combination with a special arrangement of deflection units and their attachment to the device. It should be noted that such an "off- axis" projection system also known as "lens-shift" provides a quality image without any keystone that is an obvious advantage from a system exploiting deflection mirror that shows a keystone and requires a digital keystone correction resulting in degraded performance. A Spatial Light Modulator (SLM), which may for example be constituted by a liquid crystal display (LCD) panel, preferably improved liquid crystal display panel with inside lens assembly(ies) as disclosed for example in WO03/005733, WO2004064410, WO2005036211, all assigned to the assignee of the present application, or may be a Liquid Crystal on Silicon (LCOS) display panel such as the one developed by MicroDisplay Corp, or a Digital Micro-Mirror Device (DMD) display panel such as developed by Texas Instruments, or be in the form of a matrix of controUably operated point-like light sources (such as lasers), or a raster scanning mirror based mechanism (such as presented by Micro Vision of Redmond WA, USA). Hence, it should be understood that the term "light modulation" used herein actually refers to adjusting the propagation of input light coming from a light source unit, or adjusting the light generation (emission). The SLM operates to modulate light according to a digital, video or other-picture-format image source. Considering the off-axis configuration, the SLM is placed such that the axis of light propagation of the light

beam which illuminates the SLM therethrough or therefrom is shifted relative to the optical axis of the light sources and/or a light projection optics (lens arrangement) mounted at the output of the SLM. By adjusting the deflecting unit to be in the optical path of the projected image, the user can select the required projection mode without the device masking the image.

In addition, a single system configurable for projection in a variety of modes and onto surfaces at a variety of distances should preferably provide image projection with a large depth of field. Laser light sources can provide high intensity image projection with large depth of focus and are also compact and efficient electro-optical energy converters. This combination of characteristics makes laser light sources ideally suited for use in compact projection display systems.

It is according to one embodiment, therefore, of the current invention to disclose a compact projection display system utilizing a frequently used portable electronic device, which provides multiple projection modes that can be selected by the user according to the projection environment and user's subjective preferences. The projection display system comprises an optical projection unit including at least one spatial light modulator (SLM) generating a light pattern indicative of an input signal corresponding to the data to be projected, and a light projection optics for projecting an image of said light pattern (e.g. one lens arrangement and/or scanning mirrors), and comprises at least one adjustable image deflection mechanism. Preferably, the projection display system also has at least one electronic image control mechanism (ICM) for changing orientation, shape and intensity of the projected image.

As indicated above, the SLM may be a light source unit itself or a light source unit coupled with one or more scanning mirrors, but more preferably is configured to modulate an input light beam produced by a light source unit such as at least one laser light source. It is noted that more than one light source (preferably three laser light sources) can be configured and operable for the system with different wavelengths, e.g. corresponding to three primary color components of the image. Preferably then, the SLM is a modulator such as a liquid crystal display panel or LCOS display panel, or DMD display panel, being common for the multiple light channels.

In some embodiments of the invention, the multiple projection modes provided include projection onto both front and rear projection surfaces situated in front, behind, above or below the electronic device and viewed by the user on the projection screen,

either from the side of the projection display or from the opposite side. Oblique angle projection can also be enabled by suitably configured image control mechanisms. Each projection mode requires a specific configuration of the image deflection mechanism and a specific image reorientation as well as possibly different image intensity. To facilitate this, one or more deflection mechanisms (deflectors) can be used which can each deflect the projected image through an angle between 0 and 180 degrees. In combination these can produce double deflected beams with a total deflection of 360 degrees or more. Thus the projection display system is enabled to project an image onto a surface at any angle from the device. A preferred mode is the upright mode wherein the electronic device is placed upon a desk surface and projects an image back onto the desk surface.

The compact projection display system is thus suited for use with any portable or handheld electronic device including, inter alia, a mobile phone, PDA, PMP, a laptop computer, a camcorder digital camera, memory storage device such as a. flash key, a key ring, a remote control unit, a companion projector or even a desktop computer.

It is according to a further preferred embodiment of the current invention to disclose a projection display system, comprising a portable electronic device adapted for generating digital representation of information to be projected. An image projecting unit is mounted in said portable electronic device and is configured and operable to process said digital information to generate an image thereof and direct said image externally from the portable electronic device. A deflection unit comprising at least one light deflector is mounted on said portable electronic device and can be displaced with respect to it so as to be in the optical path of the image generated by the image projecting unit. Thus the deflection unit is used for deflecting said image towards at least one desired projection surface outside the portable device. This light deflector can be adapted such that its inoperative position is outside said optical path and maybe folded into the electronic device and at least one operative position being in said optical path extending from the electronic device. Similarly the deflector can have multiple operative positions to selectively deflect the image to one of at least two different projection surfaces. The system is thereby operable in multiple projection modes, each projection mode being characterized by direction and orientation of the projected image. The image projecting unit can comprise at least one pixel matrix based micro- display spatial light modulator (SLM), such as a liquid crystal micro-display panel or

Liquid Crystal On Silicon (LCOS) display panel or Digital Micro-mirror Device (DMD) display panel, operable to modulate data indicative of said digital representation of the information to be projected to generate the image thereof; and an optical unit comprising a projection lens arrangement for directing said image to the projection surface, for example the surface of table, a wall, a piece of paper, etc. Alternatively, a 1D/2D scanning mirror arrangement is used to successively displace a collimated light beam across the projection surface, where the collimated light beam is modulated and displaced in accordance with the information to be displaced to thereby produce a projected image. In order to achieve off-axis projection, according to one embodiment, the SLM is not aligned along the optical axis of the projection lens arrangement or scanning mirror arrangement. To achieve the required degree of off-axis projection, the SLM is off-axis by at least 5% from the optical axis but preferably up to 150% of the dimensions of the SLM. In another configuration, the illuminating light beam propagation path from the light source and through the SLM is aligned off-axis with respect to the optical axis of the projection lens arrangement. According to yet another embodiment, off-axis projection is achieved by using a deflecting unit or a scanning mirror arrangement.

The projection display system allows the direction and orientation of the projected image to be configured according to the projection environment and the requirements of the user. To this end, the lens arrangement or scanning mirror arrangement is configured for directing said image with a projection angle of at least 5 degrees but preferably up to 90 degrees enabling short throw projection at a required offset from projection display system, and a minimum depth of focus ranging from 0.09- 1.0m but preferably much larger to facilitate focusing of the image for a variety of projector-display distances.

The image deflection mechanism comprises a plurality of beam deflectors which are mechanically connected to the body of the portable device in an adjustable manner. Examples of such beam deflectors include, inter alia, mirrors, prisms, polished surfaces or any combination thereof.

The image control mechanism (ICM) is operable to adjust the modulation provided by the electronic format (digital video or other-picture-format) representation of the information such that the projected image is flipped across either the horizontal

axis, the vertical axis or rotated through a predetermined angle. The ICM may also control the image intensity by controlling either the SLM or the intensity of the light sources to compensate for different projection mode screen sizes. The ICM can also provide digital correction such as geometrical distortion or keystone to compensate for effects of mirrors or projecting surfaces that are not perpendicular to the optical axis of the lens arrangement. For example, the lens shift might cause the image to shift upwards on the projection surface perpendicular to the lens arrangement optical axes; if the projection surface is tilted with respect to the optical axis then keystone correction would be required. This ICM can be hardware based, such as electronic circuitry hard- wired to flip or rotate a modulation signal to the SLM, or a mechanical arrangement configured to flip or rotate the SLM unit itself. An alternative ICM could be image manipulation software programmed to flip the modulation signal to the SLM.

The electronic ICM utilizes an internal buffer configured for storage data indicative of the full image or of at least two image rows, before operating the SLM by said data. The digital or other image data is written to the buffer row by row in reverse order, such that the first string of the image data written to the buffer becomes the last string to be transferred from the buffer to the SLM. Similarly in another embodiment, which may be an alternative or addition to the last described embodiment, the last pixel of each row written to buffer becomes the first pixel transferred to the SLM. The light source used in the projection display system is capable of producing at least one light beam and may comprise at least one beam shaper configured and operable to provide a desired cross section of the respective light beam. In particular the beam shape is used to provide a cross section of the light beam corresponding to the size of an active surface of an SLM. It is noted that the light source unit may comprise one or more light sources configured and operable for generating one or more light beams of different wavelengths to thereby produce the colored image. In this configuration a wavelength combining arrangement is incorporated for producing a combined colored image from said one or more light beams of the different colors. In one configuration, three SLMs and three beam shapers are provided such that each of the three light beams passes through its particular beam shaper and modulated by its particular SLM before the beams are combined. In another configuration three beams are recombined by the wavelength combining arrangement before being modulated by a common SLM.

Various lens arrangements are known in the art which produce wide angled projection. One enabling arrangement preferred in this invention comprises a telecentric lens, a chromatic correcting lens, a fast lens for aperture correction and an off-axis correction element. It should be noted that wide angled projection can also be achieved by a raster scanning mirror arrangement deflecting the focused light beam at a desired rate and pattern (directions). Thus, the optical image projection unit may include at least one scanning mirror arrangement illuminated by an illuminating light beam and operable to raster scan light beam with intensity indicative of the electronic format representation of the data to be projected to generate the image thereof. The scanning mirror arrangement and illuminating light beam may be configured with an off-axis mode with respect to an optical axis of the light source arrangement. The scanning mirror arrangement may be configured for projecting the image with a projection angle of at least 20 degrees. As for the lens arrangement, it may be configured to provide a depth of focus of a range of at least 0.09-1.0m. A particular embodiment of the invention is a mobile phone device carrying a projecting unit thereinside. An aperture in a mobile phone device allows a light output of the projecting unit to propagate externally from the mobile phone device and a light deflection unit comprising at least one light deflector is carried either inside or on the outer surface of the mobile phone device such that it can be unfolded or otherwise adjusted with respect to the mobile phone device and the optical projection unit thereinside so as to be in the optical path of said output light and thus deflecting it to at least one desired projection surface outside the mobile phone device.

It is an additional object of the invention to teach a method of projecting an image with multiple projection modes, the method comprising selectively deflecting an image output from a projecting unit into multiple desired directions towards selective projection surfaces. The method further comprises incorporating the projecting unit into a portable electronic device adapted for generating a digital representation of information to be projected, and mounting a deflection unit inside or on said portable device in a manner allowing selective displacement of the deflection unit with respect to the projecting unit so as to be in the optical path of the image output from the projecting unit.

Thus, according to one broad aspect of the invention there is provided a projection display system, comprising: a portable electronic device adapted for

generating an electronic format representation of data to be projected, an optical image projecting unit mounted in or connected to said portable electronic device, the optical image projection unit being configured and operable to process said electronic data to generate an optical image thereof and direct said image optically from the portable electronic device; and a deflection unit comprising at least one light deflector mounted on and displaceable with respect to said optical image projecting unit so as to be in an optical path of said image generated by the image projecting unit for deflecting said image towards at least one desired projection surface outside the portable device.

It should be understood that the term "electronic format" used herein signifies digital, video or other picture format.

According to another broad aspect of the invention there is provided a mobile phone device carrying an optical image projection unit thereinside, and having an aperture allowing light output of said optical image projection unit to propagate externally from the mobile phone device, and carrying a light deflection unit comprising at least one light deflector displaceable with respect to an optical path of said output light so as to selectively be in said optical path for deflecting the output light to at least one desired projection surface outside the mobile phone device.

According to another broad aspect of the invention, there is provided a method of projecting an image with multiple projection modes, the method comprising selectively deflecting an image output from an optical image projecting unit into multiple desired directions towards selective projection surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be carried out in practice, preferred embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 schematically shows an example of a compact projection display system of the present invention;

Figs. 2A to 2F show six examples, respectively, of the configuration and operation of the compact projection display system of the present invention, where

Fig. 2A shows the system operation with a directed forward and off axis projection mode onto a front projection surface;

Fig. 2B shows the system in which the image is deflected backwards; Fig. 2C shows the system in which a portable device, carrying the optical projection unit, stands upright on a horizontal and the projected image is deflected back down onto a projection surface; Fig. 2D shows the system in which the image is deflected twice thereby providing a forward projected image of larger dimensions and projected onto a front projection surface;

Fig. 2E shows the system in which the image is deflected backwards towards a rear projection surface; Fig. 2F shows the system in which the image is deflected twice thereby providing a forward projected image of larger dimensions and projected onto a rear projection surface;

Fig. 3 exemplifies a compact projection display system of the present invention, which utilizes PMP or a portable communication device such as a mobile phone carrying the optical projection unit, and which operates in a normal forward projection mode;

Fig. 4 illustrates a compact projection display system of the present invention formed by an electronic device, such a PDA, or PMP, or mobile phone, carrying the optical projection unit, and operating in a short throw upright projection mode; Fig. 5 illustrates a compact projection display system of the present invention formed by an electronic device, such as a mobile phone, carrying the optical projection device, and operating in a short throw double projection mode;

Fig. 6A and 6B show two examples, respectively, of the configuration and operation of an optical scheme of the compact projection display system; Fig. 7 shows yet other example of the configuration and operation of an optical scheme of the compact projection display system in off-axis mode, enabling short throw projection;

Fig. 8 exemplifies the implementation of the system of the present invention formed by an electronic device carrying the optical projection unit and configured for short throw projection modes;

Figs. 9a and 9b illustrate the compact projection display system of the present invention including the optical projection unit integrated into a mobile phone and operable (a) in normal projection mode and (b) in short throw projection mode;

Figs. 10a and 10b illustrate the compact projection display system of the present invention including the optical projection unit integrated into a laptop computer and operable (a) in normal mode and (b) in short throw projection mode; and

Figs. 11a and lib illustrate the compact projection display system of the present invention including the optical projection unit integrated into a camcorder and operable (a) in normal mode and (b) in short throw projection mode.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Referring to Fig. 1 there is schematically illustrated an example of a compact projection display system, generally designated 1000. The system 1000 includes an optical projection device 2 and a deflection unit 10. The optical projection device 2 is carried inside a portable electronic device ED (such as a mobile phone, PDA, standalone projection display, etc.), and the deflection unit 10 is carried by the electronic device being located inside the electronic device, or mounted on the outer surface of the electronic device, or having inside and outside light deflecting elements. The optical projection unit 2 generates an image of certain information created by the electronic device.

The optical projection unit 2 is connected to an image source 1610, which is an electronic circuit of the portable electronic device ED and provides an image signal 1615 to operate the optical projection unit. As shown in the present example, the electronic circuit also preferably includes an image control mechanism (ICM) 1620 (software and/or hardware utility) configured to appropriately modulate the image signal so as to cause flipping of the respective light pattern generated by the optical projection unit across the horizontal or vertical axis, or cause its rotation through a predetermined angle. The ICM operates to generate an image signal to operate a light source system to produce a light pattern indicative of the image signal. In the present example, the light source system includes a light source unit (light emitter(s)) 1630 and a spatial light modulator (SLM), 1040, such as a liquid crystal display panel or LCOS display panel or DMD display panel. The SLM modulates a beam of light 1635 produced by the light source 1630 to produce the desired light pattern. It should however be understood that alternatively the light source system may include at least one matrix of point-like light sources (lasers) or a point like light source (laser)

combined with a scanning mirror arrangement. The image signal from the ICM 1620 may be a signal 1625 to operate the SLM 1040 or a signal 1625' to control the light source 1630 power or duty cycle.

Further provided in the optical projection unit is a light projection optics 4 (lens arrangement in the present example) accommodated at the output of the light source system, i.e. at the output of the SLM 1040 in the present example. The modulated light 1645 passes through the lens arrangement 4 producing a projected image 1655. As will be described further below, the lens arrangement is preferably configured to produce a wide angle projection image. It should be understood that in the case where the SLM is constituted by a combination of point like light sources combined with a scanning mirror arrangement, the lens arrangement is not required.

The deflection unit 10 is locatable in the optical path of light emerging from the lens arrangement to deflect the projection image (light pattern) onto a projection surface 26. The projection mode(s) is(are) selected by the orientation of the deflection unit 10, preferably in combination with the image signal modulation produced by the ICM 1620.

Reference is made to Figs. 2A-2F exemplifying the operational principles of a projection display system of the present invention for, respectively, six different projection modes. The projection display system includes an electronic device (not shown here) of the kind capable of generating digital representation of certain information. Generation of information can be initiated by the device electronics in response to user's direct input to the device or in response to data coming from a communication network. Such an electronic device may thus be a communication device. Generally speaking this may be a phone device, e.g. mobile phone, a personal computer (Laptop computer), personal digital assistant (PDA), digital camera, etc. The electronic device carries a compact projection display system, appropriately connectable to the electronic block of the portable electronic device for optically processing the digital information to be projected, and a deflection unit (not shown here) configured to be locatable in an optical path of an image output from the projecting unit.

Fig. 2A shows a first projection mode in which the compact projection unit 2 having an appropriate lens arrangement 4 (preferably configured to provide a wide angle light propagation as will be described more specifically further below) directs an image, off axis with respect to the projecting unit, towards a front projection surface 26 to be viewed by an observer 28 in front of the projection surface. In this configuration,

the image might not undergo any deflection, and therefore the deflection unit if used can be in its folded inoperative position being outside the optical path of light coming from the lens arrangement. The distance between the optical projection unit and the projection surface determines the size of the projected image, but due to the large depth of focus, high resolution images are obtained over a large range of distances.

Fig. 2B represents a second projection mode in which the projection display device 2 with its lens arrangement 4 projects an image towards a deflection unit 10 which in the present example is constituted by a single mirror. The deflection unit deflects the image output from the projecting unit back towards a projection surface 26 situated behind the electronic device, and the image is viewed by an observer 28 in front of the projection surface. In this configuration, the image undergoes one reflection and so the image is previously corrected electronically by reversing the image in the horizontal plane (right to left and left to right) while being created in the projecting unit. As described above, this can be implemented by operating an SLM (not shown) of the projecting unit with a reversed representation of the digital information to be projected.

Fig. 2C exemplifies a third projection mode in which the optical projection unit 2 with its lens arrangement 4 is placed upright upon a horizontal surface. The device projects an image towards a deflection unit 10 (single mirror in the present example), which deflects the image backwards upon the horizontal projection surface 26, the image is viewed by an observer 28. In this configuration, the image undergoes one reflection, so the image is corrected electronically by reversing the image in the horizontal plane. In addition, because of the orientation of the viewer 28 it is also necessary to reverse the image in the vertical plane (up down and down up).

Fig. 2D shows an example of a fourth projection mode in which the optical projection unit 2 with its lens assembly 4 projects an image towards a deflection unit 10 formed by a first deflector (mirror) 1OA which deflects the image back towards a second deflector (mirror) 1OB which in turn deflects the image onto a front projection surface 26 situated in front of the electronic device. The image is viewed by an observer 28 in front of the projection surface.. It should be noted that in this configuration, the image undergoes two reflections and so the image requires no correction (reorientation). This configuration is particularly useful where a large projected image is required but the spatial constraints limit the distance between the projecting unit and the projection surface.

Fig. 2E exemplifies a fifth projection mode in which the optical projection unit 2 with its lens arrangement 4 projects an image towards a deflection unit 10 (single deflecting mirror), which deflects the image back towards a rear projection surface 26 situated behind the optical projection unit. The image is viewed by an observer 28 situated behind the projection surface. Note that in this configuration, the image undergoes one reflection but because of the orientation of the viewer, 28 no image correction is necessary.

Fig. 2F is an example of a sixth projection mode in which the optical projection unit 2 with its lens assembly projects an image towards a deflection unit 10 having a first deflecting mirror 1OA, which deflects the image back towards a second deflecting mirror 1OB, which in turn deflects the image onto a rear projection surface 26, situated in front of the projector unit, the image is viewed by an observer 28 situated behind the projection surface. In this configuration, the image undergoes two reflections but because of the orientation of the viewer 28 the image is corrected (reoriented) electronically by reversing the image in the horizontal plane.

Reference is made to Figs. 3-5 illustrating operation of a projection display system of the present invention with various projection modes. Fig. 3 shows various examples of the normal forward projection, in which the projection display systems utilize a mobile phone and a PMP as an electronic device carrying the optical projection unit. Fig. 4 illustrates a projection display system (utilizing an electronic device carrying the optical projection unit 2 and the deflection unit 10) operating with the upright mode of projection back to the supporting horizontal surface, such as a desk surface. Fig. 5 illustrates a projection display system operating with the double deflection short throw projection mode, i.e. the deflection unit is formed by two light deflecting units.

Referring to Figs. 6A and 6B, there are shown two examples, respectively, of the optical scheme of the compact projection display system 1000 of the present invention. In the present example, the system operation in the normal forward projection mode is shown. The system 1000 includes an optical projection unit 2 for incorporating in a portable electronic device (not shown), and a deflection unit 10 for mounting on the portable electronic device. The optical projection unit 2 is configured for creating an image corresponding to certain digital information. To this end, the optical projection unit includes a light emitting arrangement and a light modulating

arrangement operable to generate a light pattern indicative of the image to be projected. In the example of Fig. 6 A, the optical projecting unit 2 includes a light source unit and an SLM 1040. As indicated above, the same (creation of a light pattern indicative of the information to be projected) could be implemented by at least one matrix of point-like light sources (which is not specifically shown); or as shown in Fig. 6B by using a point like light source (i.e. a light source producing a collimated light beam) combined with a scanning mirror arrangement 1040.

The light source unit may include at least one light source. In the present example, the light source unit includes three light sources (lasers) 1001, 1002 and 1003 producing light beams of three primary colors (blue, red and green) respectively. Also, in the present example, the light source unit includes beam shaping optics in the form of three beam shapers (e.g. diffractive elements) 1011, 1012 and 1013 associated with three light beams, respectively. The beam shaper is configured to provide a desired cross section of the respective light beam. Further provided in the optical projecting unit 2 is a beam combiner 1020 including two wavelength-selective elements (dichroic mirrors) 1021 and 1022 and a light directing unit formed by two reflectors (mirrors) 1023 and 1024 for directing the two beams towards the dichroic mirrors. The so- produced combined beam 1025 is directed by a field lens 1030 onto the SLM (Fig. 6A) or scanning mirror arrangement (Fig. 6B) 1040. The SLM or scanning mirror arrangement is operated as described above by an electronic block of the portable electronic device to modulate this light beam in accordance with the digital information to be imaged. The operation of the liquid crystal display based SLM or LCOS or DMD is known per se and therefore does not need to be specifically described. As for the operation of the scanning mirror arrangement it is also generally known and does not need to be described in detail, except to note that it may include two one-directional scanning mirrors that first scan the light beam in the horizontal axis and then scan the light in the vertical axis, or it may include a single 2D scanning mirror that scans the light in both the horizontal and the vertical axis.

Considering the example of Fig. 6A ₅ the modulated light output from the SLM passes through a lens arrangement 4. The lens arrangement is configured to provide a wide angle light propagation towards a projection surface 26. In the system configuration of Fig. 6B, no projection lens arrangement is used.

A deflection unit 10 is in the form of a folding mirror displaceable between its inoperative folded position being outside the optical path of light beam output from the lens arrangement (Fig. 6A) or scanning mirror arrangement (Fig. 6B) and an operative position being in the optical path of said light. When the deflection unit is in its inoperative position, the image is projected onto the surface 26 in its original direction in which it emerges from the lens arrangement or scanning mirror arrangement. Shifting the deflection unit into its operative position (as shown in the figure in dashed lines) would result in the system shift into a different projection mode.

Fig. 7 exemplifies the optical scheme of another example of the projection display system 1000 with off-axis arrangement. The same reference numerals are used for identifying those components that are common in all the examples of the invention. The system 1000 is constructed in general similarly to the above-described system of Fig. 6A, namely the separate light beams are combined by the optical arrangement 1020, and the combined beam 1025 is directed to pass through the SLM 1040, but in the present example in distinction to that of Fig. 6 A the SLM is not aligned along the optical axis of the projection lens arrangement 4. As a result the off-axis nature of the projected image is obtained.

As shown in Fig. 7, the SLM 1040 is accommodated off-axis with respect to the lens arrangement, namely such that an axis Al of light propagation through the SLM is spaced-apart from the optical axis A2 of the lens arrangement. This results in an off-axis projected image which is directed away from the body of the electronic device carrying the optical projection unit thereinside so as to minimize beam masking in deflected projection modes.

The lens arrangement is configured to provide a desirably wide angle of light propagation and also to correct for the off-axis configuration. To this end, the lens arrangement includes a telecentric lens 1051, a chromatic correcting lens 1052 (such as an achromatic or apochromatic lens), a fast lens for aperture correction 1052, and an off axis correction element 1053. This lens arrangement is configured to produce a projection angle of about 90 degrees with off-axis projection of up to 130% that is a shift of the SLM center from that of the projection lens arrangement, as a percent of the semi-dimensions of the SLM (where e.g. 0% is "On- Axis" and 100% off axis is when the bottom of the SLM coincides with the center of the previous "on-axis" SLM). The compact nature of the device limits the lens length to below 30mm and the numerical

aperture is above 0.15. The arrangement is designed to provide high resolution images with distortion below 1.5% for all wavelengths within the range of visible light.

Fig. 8 exemplifies the mechanical details in implementation of the system of the present invention formed by an electronic device carrying the projection display system configured for upright short throw projection modes with flipping mirror. The mirror may be either opened or closed providing either the above-described mode of Fig. 2B or that of Fig. 2A.The figure further shows (in the last two drawings) the ray tracing from the SLM to the projection surface in view from the side and in view from the top, all for the case where the flipping mirror is closed and does not change the path of the rays. Reference is made to Figs. 9-11 showing how a compact projection display system can utilize a variety of frequently used portable devices.

Figs. 9a and 9b show a compact projection display system in which the optical projection unit is integrated into a mobile phone 1300 and the deflection unit is mounted on the outer surface of the mobile phone being displaceable with respect to the mobile phone body (housing). Fig. 9a shows a forward mode projection onto a projection surface 26, at a distance of 0.262m from the optical projection unit. In Fig. 9b an adjustable deflection unit 10 has been introduced into the path of the projected image after being unfolded from the mobile phone device such that the image is projected onto another projection surface 26'. A somewhat similar configuration in Figs. 10a and 10b represent the compact projection display system utilizing a laptop computer 1400. Fig. 10a shows a forward mode projection onto a projection surface 26, at a distance of 0.812m from the optical projection unit located inside the laptop computer. In Fig 10b an adjustable deflection unit 10 has been introduced into the path of the projected light such that the image is proj ected onto another proj ection surface 26 '.

Figs. 11a and lib demonstrate how the compact projection display system is integrated into a camcorder 1500. Fig. 11a shows a rear deflected mode projection wherein an adjustable deflection unit 10 has been introduced into the path of the projected light such that the image is reflected back onto a first projection surface 26. In Fig. lib a display screen 1530 has been unfolded from the laptop computer to intercept and display the projected image (i.e. presenting a second projection surface).

Thus, the present invention provides a simple, compact projection display system enabling incorporation of an optical projection unit in any frequently used

electronic device, such as mobile phone, PDA, PMP, laptop, a stand alone projector display, etc., and using a deflection unit (e.g. mirror) attached to the electronic device in a manner allowing its displacement with respect to an optical path of light output from the optical projection unit. This allows selective use of the deflection unit, i.e. selective shift of the deflection unit from its inoperative (folded) position into its operative position, as well as selective shift of the deflection unit between its various operative positions, thereby enabling multi-mode system operation, i.e. image projection on multiple different projection surfaces.

Those skilled in the art will readily appreciate that various modifications and changes can be applied to the embodiments of the invention as hereinbefore described without departing from its scope as defined in and by the appended claims.