WO2016075437A1

WO2016075437A1 - Image display system

Info

Publication number: WO2016075437A1
Application number: PCT/GB2015/053306
Authority: WO
Inventors: Martin Richardson
Original assignee: De Montfort University
Priority date: 2014-11-12
Filing date: 2015-11-03
Publication date: 2016-05-19
Also published as: GB201420118D0; GB2532234A; GB2532234B

Abstract

An image display system (10) comprises a three-dimensional digital holographic image (4) and an image projection device (18) for generating and projecting a virtual image (20). A partially-transparent reflective projection screen (22) is inclined at an angle relative to the projected virtual image (20) and is located in front of the digital holographic image 4) such that the digital holographic image (14) is visible through the projection screen (22). The image projection device (18) is arranged to project the virtual image (20) onto the projection screen (22) to produce a reflected image (28) which is superimposed onto at least part of the digital holographic image (14) visible through the projection screen (22).

Description

IMAGE DISPLAY SYSTEM

Technical Field

The present disclosure relates generally to an image display system and to a method for displaying an image using an image display system.

Technical Background

In the field of display holography, developments have occurred which enable full colour three-dimensional holographic images to be produced. These images may be the product of computer graphics and may be in the form of transmission or reflection holograms. Holograms provide complex three-dimensional displays which can be 'animated', but the animation is a permanent and limited function of their "stereographic" (multi-channel) image basis. Thus, a viewer moving in relation to the "viewing window" of the hologram is able to experience three-dimensional effects and animation, but these are simply a function of the viewer's position and of the viewer's binocular vision capability.

The limited 'animation' capability associated with current display holography techniques is a drawback and the present disclosure seeks to address this.

Summary of the Disclosure

According to a first aspect of the present disclosure, there is provided an image display system comprising:

a three-dimensional digital holographic image;

an image projection device for generating and projecting an image;

a partially-transparent reflective projection screen inclined at an angle relative to the projected image and located in front of the digital holographic image, the digital holographic image being visible through the projection screen;

the image projection device being arranged to project the image onto the proj ection screen to produce a reflected image which is superimposed onto at least part of the digital holographic image visible through the projection screen. According to a second aspect of the present disclosure, there is provided a method for displaying an image using an image display system according to the first aspect, the method comprising projecting an image onto a front surface of the projection screen using the image projection device to produce a reflected image which is superimposed onto at least part of the three-dimensional digital holographic image visible through the projection screen.

The reflected image may be a three-dimensional image or may be a two-dimensional image.

The use of an inclined partially-transparent reflective projection screen, of which the viewer is not aware, enables a reflected image to be produced using what is commonly known as the 'Pepper's Ghost' technique. By overlaying this reflected image onto the three-dimensional digital holographic image, the animation capabilities of the digital holographic image are significantly enhanced, in particular because the user does not have to move in relation to the holographic image to experience the animation effects. This enhanced animation capability can be useful in many environments.

The three-dimensional digital holographic image and the image generated and projected by the image proj ection device are typically produced from the same source image data. This ensures that there is complete continuity and alignment between the 'permanent' digital holographic image and the 'virtual' image generated and projected by the image projection device. The image generated and projected by the image projection device may be a static image. More typically, the image generated and projected by the image projection device may be a moving image. A moving image may provide an enhanced animation experience for the user. The image display system may include a controller which may be responsive to an external stimulus and the controller may be arranged to control the operation of the image projection device based on the external stimulus. Thus, the animation effect provided by the projected image may be controlled based on the external stimulus.

Any suitable external stimulus may be used, such as an audio stimulus. Thus, the projected image could be synchronised with a suitable audio musical sequence.

More typically, the external stimulus may be a user stimulus. Thus, the actions of a user could be used to control the projected image. In a first embodiment, the controller may be a proximity sensor, such as a passive infrared (PIR) sensor, arranged to detect the presence of a user, for example in proximity to the image display system and may be arranged to activate the image projection device upon detecting the presence of a user. In this embodiment, the image projection device is activated only when a user is in proximity to the image display system.

In a second embodiment, the controller may be a motion-tracking sensor which may be arranged to detect the movement of a user. Thus, as a user moves in relation to the image display system, the controller can control the image projection device to change the image dependent upon the user's physical location in relation to the image display system, ensuring that the reflected image is accurately aligned and synchronised with the digital holographic image.

In a third embodiment, the controller could be an eye-tracking sensor. In a fourth embodiment, the controller may be a touch screen which may be positioned in front of the projection screen. The touch screen can be arranged to overlay the displayed image formed by the digital holographic image and the reflected image and can appear to form part of the displayed image and allow it to be controlled. In one implementation, the touch screen can be a projected touch screen, for example a projected infra-red matrix touch screen. The projection screen may be a foil or a film. The projection screen may comprise a biaxially oriented polymeric film. One suitable polymeric film is Hostaphan® available from Mitsubishi Polyester GmbH. The projection screen may alternatively comprise a holographic screen.

The image projection device may be a liquid crystal display (LCD) projector or a light- emitting diode (LED) projector and may be embodied as a television screen. The image projection device could be a slide projector or a spatial light modulator (SLM) proj ector.

In accordance with the second aspect, the method may comprise controlling the operation of the image projection device based on an external stimulus, for example a user stimulus. As mentioned above, this enables the 'animation' effect provided by the projected image to be controlled based on the external stimulus.

The method may comprise activating the image projection device in response to the external stimulus. Alternatively or in addition, the method may comprise modifying the image generated and projected by the image projection device in response to the external stimulus.

Brief Description of the Drawings

Figure 1 is a diagrammatic plan view of an image display system according to a first embodiment of the present disclosure; and

Figure 2 is a diagrammatic side view of an image display system according to a second embodiment of the present disclosure.

Detailed Description of Embodiments

Embodiments of the present disclosure will now be described by way of example only and with reference to the accompanying drawings.

Referring initially to Figure 1, there is shown in plan view an image display system 10 comprising a hologram plate 12 at the rear of the display system 10 to provide a three- dimensional digital holographic image 14 which can be viewed by a user from the front of the display system 10. The holographic image 14 can be viewed by a user 15 from any one of a number of positions in a viewing region 16 and as the user 15 moves to different positions in the viewing region 16, the user 15 will experience some limited animation effects. In the illustrated embodiment, the three-dimensional holographic image 14 is represented by a simple cube shape, but it will be understood that this is provided merely by way of example and that any suitable holographic image 14 can be provided. A suitable illumination source is provided for the hologram plate 12, but this is not shown in Figure 1.

The image display system 10 comprises an image projection device 18 which generates and projects an image 20 onto a projection screen 22. In the illustrated embodiment, the image projection device 18 is located to one side of the projection screen 22, but other positions can be adopted (see e.g. Figure 2) provided that the projection screen 22 is suitably repositioned. The image projection device 18 shown in Figure 1 is a LCD or LED projector, but other projection devices can be used. In the illustrated embodiment, the image 20 generated and projected by the image projection device 18 is represented by the word 'fantom', but it will be understood that this is provided merely by way of example only and that any suitable image 20 can be used.

The projection screen 22 is a partially-transparent reflective projection screen and is inclined at an angle Θ relative to the projected image 20. In the illustrated embodiment, the projection screen 22 is inclined at an angle Θ of approximately 45° with respect to the image 20 generated and projected by the image projection device 18. The projection screen 22 is supported with its screen axis in the horizontal plane and in a smooth and wrinkle-free state by a frame 24 which is formed by a plurality of frame members 26, only two of which are shown in Figure 1. One of the illustrated frame members 26 has a telescopic portion 26a which can be extended and retracted in order to control the inclination angle Θ.

The projection screen 22 can comprise any suitable material which is reflective, so that the image 20 generated and projected by the image projection device 18 is reflected from the front surface of the projection screen 22, and also partially-transparent, so that a user may view through the projection screen 22 the holographic image 14 located behind the projection screen 22. The projection screen 22 could, for example, comprise a biaxially oriented polymeric film or could be a holographic screen in which a plurality of microlenses are provided as a coating on a support film.

The image 20 generated and projected by the image projection device 18 is reflected from the front surface of the projection screen 22 to provide a reflected image 28 (often referred to as a 'Pepper's Ghost' image) which is superimposed onto at least part of the holographic image 14 positioned behind the projection screen 22. The reflected image 28 of the word 'fantom' is two-dimensional in the illustrated embodiment, but the reflected image 28 could, of course, be three-dimensional dependent upon the image 20 generated and projected by the image projection device 18. The holographic and reflected images 14, 28 both appear to a user 15 in the viewing region 16 to be seamlessly integrated and the reflected image 28 provides enhanced animation of the combined image, formed by the holographic and reflected images 14, 28.

In order to ensure that a user 15 in the viewing region 16 is unaware of the components forming the display system 10 and to thereby preserve the integrity of the illusion, barriers 30 are provided to restrict the movement of the user in relation to the display system 10 and screens 32, for example surfaced with non-reflective light absorbent material, are provided to obscure certain components of the system 10.

Referring now to Figure 2, there is shown a side view of an image display system 40 which is similar to the image display system 10 of Figure 1 and in which corresponding features are identified using corresponding reference numerals.

In the image display system of Figure 2, a hologram plate 12 is again used to provide the digital holographic image 14. The hologram plate 12 is illuminated from the front by a light source 42, such as a tungsten light bulb, a LED, a LED array of suitable spectrum, or in some circumstances by a powerful projection lamp with focussing properties which essentially acts as a point source of light. In the illustrated embodiment, the light from the light source 42 is directed and focussed onto the front of the hologram plate 12 by an optical element 44 to provide optimum illumination of the hologram plate 12. Although the arrangement shown in Figure 2 shows a 'front projection' hologram, it will be appreciated that the hologram plate 12 could be illuminated from the rear to provide a 'rear projection' hologram.

In the embodiment of Figure 2, the projection screen 22 is supported by the frame members 26 in a different orientation with its screen axis in the vertical plane. Accordingly, the image projection device 18, which in this embodiment comprises a television screen, is mounted above the projection screen 22 and projects the image 20 downwardly onto the front surface of the projection screen 22. Again, the projection screen 22 is inclined at an angle Θ of approximately 45° with respect to the image 20 generated and projected by the image projection device 18 and the frame member 26 has a telescopic portion 26a which can be extended and retracted in order to control the inclination angle Θ.

As in the embodiment of Figure 1, barriers 30 are provided to restrict the movement of the user in relation to the display system 40 and screens 32, for example surfaced with non-reflective light absorbent material, are provided to obscure certain components of the system 40.

The operation of the image projection device 18 is controlled by a controller in the form of a passive infra-red (PIR) sensor 46 or other type of proximity sensor. In this arrangement, the image projection device 18 is activated only when a user 15 or users are detected by the PIR sensor 46 in proximity to the image display system 40.

In addition, a touch screen 48, such as a projected infra-red touch screen, is positioned in front of the projection screen 22 where it can be easily accessed by a user 15 and the outputs from the touch screen 48 can be used to control the image projection device 18, for example to modify the projected image 20 in a suitable manner. In the embodiments illustrated in Figures 1 and 2, the image 20 generated and reflected by the image projection device 18 is a static image. More typically, it is preferred that a moving image is generated and projected by the image projection device 18 as this provides enhanced animation effects.

In one example and with particular reference to Figure 2, the three-dimensional digital holographic image 14 (i.e. the 'permanent' part of the complete image) could be a representation of a cross-section of a car engine with the crank shaft in relative shadow. The reflected image 28 (i.e. the 'virtual' animated part of the complete image), generated and projected by the image projection device 18 and reflected by the projection screen 22, could be a rotating crankshaft. In the resulting complete image seen from the viewing region 16, the reflected image 28 of the rotating crankshaft would appear to a user to be superimposed into the void space in the holographic image 14 providing a complete image of a car engine with enhanced animation effects (i.e. a rotating crankshaft) as compared to a digital holographic image 14 alone of both the engine and crankshaft. In this example, the PIR detector 46 detects the presence of a user in proximity to the image display system 40 and only activates the image projection device 18 when a user is present. At other times, the image projection device 18 is inactive. Further, some user interaction with the reflected image 28 of the crankshaft is provided by the touch screen 48, although this can be omitted if desired. The touch screen 48 is suitably aligned with the digital holographic image 14 and the reflected image 28 of the crankshaft so that interaction with different regions of the touch screen 48 causes the image projection device 18 to appropriately modify the projected image 20 according to the region of the reflected image 28 of the crankshaft and/or the holographic image 14 of the engine which the user perceives that he is interacting with.

In another example, the holographic image 14 (i.e. the 'permanent' part of the complete image) could be a representation of a party scene in which a void in the general panorama contains a designed in blank space. The reflected image 28 (i.e. the 'virtual' animated part of the complete image), generated and projected by the image projection device 18 and reflected by the projection screen 22 into the void space, could be a dancer. The image display system 10, 40 could be arranged to modify the image 20 generated and projected by the image projection device 18 in response to an external audio stimulus, for example so that the movements of the dancer embodied as the reflected image 28 are coordinated with the external audio stimulus. In order to ensure that there is proper continuity between the digital holographic image 14 and the image 20 generated and projected by the image projection device 18, the two images are generated using the same image source data, in other words using the same root computer graphics. For example, a complete image (whether static or dynamic in the form of a video sequence) is generated or recorded and is processed using a suitable rendering application such as Cinema 4D (registered trade mark). A hologram plate 12 is then created which contains the 'permanent' part of the image that is to be represented as the three-dimensional digital holographic image 14. The 'virtual' animated part of the image is then projected by the image projection device 18 so that it is overlaid as the reflected image 28 onto the digital holographic image 14, whereby the reflected image 28 is synchronised with the holographic image 14.

Although exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments. Each feature disclosed in the specification, including the claims and drawings, may be replaced by alternative features serving the same, equivalent or similar purposes, unless expressly stated otherwise. Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like, are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to". Any combination of the above-described features in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

1. An image display system comprising:

a three-dimensional digital holographic image;

an image projection device for generating and projecting an image;

the image projection device being arranged to project the image onto the projection screen to produce a reflected image which is superimposed onto at least part of the digital holographic image visible through the projection screen.

2. An image display system according to claim 1, wherein the three-dimensional digital holographic image and the projected image are produced from the same source image data.

3. An image display system according to claim 1 or claim 2, wherein the image generated and projected by the image projection device is a static image.

4. An image display system according to claim 1 or claim 2, wherein the image generated and projected by the image projection device is a moving image.

5. An image display system according to any preceding claim, wherein the image display system includes a controller responsive to an external stimulus and the controller is arranged to control the operation of the image projection device based on the external stimulus.

6. An image display system according to claim 5, wherein the external stimulus is a user stimulus.

7. An image display system according to claim 6, wherein the controller is a proximity sensor arranged to detect the presence of a user in proximity to the image display system and is arranged to activate the image projection device upon detecting the presence of a user.

8. An image display system according to claim 6, wherein the controller is a motion-tracking sensor arranged to detect the movement of a user.

9. An image display system according to claim 6, wherein the controller is an eye- tracking sensor.

10. An image display system according to claim 6, wherein the controller is a touch screen positioned in front of the projection screen.

11. An image display system according to claim 10, wherein the touch screen is a projected touch screen.

12. An image display system according to claim 11, wherein the projected touch screen is an infra-red matrix touch screen.

13. An image display system according to any preceding claim, wherein the projection screen is selected from the group consisting of a foil and a film.

14. An image display system according to claim 13, wherein the projection screen is a polymeric film.

15. An image display system according to claim 13, wherein the projection screen is a holographic film.

16. An image display system according to any preceding claim, wherein the image projection device is selected from the group consisting of a liquid crystal display (LCD) projector, a light-emitting diode (LED) projector, a slide projector and a spatial light modulator (SLM) projector.

17. An image display system according to any preceding claim, wherein the image projection device is a television screen or a liquid crystal display (LCD) screen.

18. A method for displaying an image using an image display system according to any preceding claim, the method comprising:

proj ecting an image onto a front surface of the proj ection screen using the image projection device to produce a reflected image which is superimposed onto at least part of the three-dimensional digital holographic image visible through the projection screen.

19. A method according to claim 18, wherein the method comprises controlling the operation of the image projection device based on an external stimulus.

20. A method according to claim 19, wherein the method comprises activating the image projection device in response to the external stimulus.

21. A method according to claim 19 or claim 20, wherein the method comprises modifying the image generated and projected by the image projection device in response to the external stimulus.

22. An image display system substantially as hereinbefore described and/or as shown in the accompanying drawings.

23. A method for displaying an image substantially as hereinbefore described with reference to the accompanying drawings.