GB2431036A

GB2431036A - Rotating multiple image display

Info

Publication number: GB2431036A
Application number: GB0517762A
Authority: GB
Inventors: Roy Booth
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-09-01
Filing date: 2005-09-01
Publication date: 2007-04-11
Also published as: GB0517762D0

Abstract

A multiple image display comprises two or more images which are transformed into three dimensional helixes having an axis in the viewing direction, and arranged such that the images may move on a helical path relative to one another with one image being brought into view while the other image is obscured. The image helixes may each be segmented such that the segments of one image, when following a helical path, pass through the space between the segments of the other image (figure 5). The helical motion may be produced using stepping motors, or may be produced as a result of (i) a change in either angular or linear momentum induced by acceleration or deceleration of the display, (ii) a change in orientation of the display with respect to gravity or a magnetic field, or (iii) a change in an external magnetic field. The multiple image display may form part of a larger display, with the multiple image display being fully visible or partially obscured (figure 6).

Description

I

Rotating Multiple Image Display This invention relates to a device for displaying multiple images within a single viewing frame.

There are already a number of technologies in existence for displaying two or more images within a single viewing frame.

One such technology uses rotating triangular louvers which have rectangular slices' of two or three images attached to alternate faces of a triangular column. The viewing frame contains a number of such columns arranged parallel to each other and closely spaced. The columns are rotated synchronously so that two or three complete images are reconstructed from the corresponding image slices' over a period of time Although conceptually simple such an arrangement can suffer a number of practical disadvantages. Small spaces need to be provided between adjacent columns to maintain mechanical clearance. To allow for manufacturing tolerances and thermal expansion these spaces are typically sufficiently large as to be visible from a distance and impart a striped' appearance to the observed image.

This apparent striped' effect can become exaggerated by mechanical practicalities such as back-lash and gear wear which result in imprecise alignment of the column faces i.e. the image strips' become non-coplanar.

Mechanical reliability can also be an issue due to the large number of moving parts e.g. gears, belts, chains and bearings. The mechanical complexity often limits the speed at which the columns can rotate and also imparts a cost burden.

Further mechanical problems can exist due to the fact that each column can only be supported at its endpoints. Although these problems can be minimised by arranging the columns vertically instead of horizontally the balance between column stiffness' and weight can become a problem for large signs.

A more fundamental disadvantage of this type of display is the fact that it is limited to a maximum of three different images.

An alternative to the rotating triangular column technology which can display more than three images uses two rollers and a flexible belt' upon which images are printed.

The ends of the belt' are wrapped around the two rollers which are spaced in such a way as to expose one image to the viewing window.

Both rollers are then synchronously rotated a defined number of turns to bring each subsequent image into view.

Unfortunately, reliability problems exist with most practical implementations of this type of technology. These are principally due to manufacturing tolerances, belt' wear and differential thermal expansion which can result in frequent jamming of the belt'.

Also, the rotational speed, acceleration and deceleration of each roller needs to be accurately controlled to prevent the belt' ripping, sagging or jamming.

Furthermore, as more of the belt' moves from one roller to the other this necessitates an adjustment in the relative roller angular speeds to allow for the increase and decrease in roller circumferences.

A much simpler technology exists for displaying multiple images which has no moving parts. Essentially two or more images are separated into very thin strips' and printed in an interlaced manner either onto a backing material over which is placed a lenticular lens or directly onto the back of a lenticular lens which is subsequently covered with a backing material.

The optical geometry of the lenticular lens is such that it selectively makes visible all the strips' from a particular image and hides from view all the strips' of the other images dependant upon viewing angle.

Whilst this type of multi-image technology does not require any power to operate it has a number of disadvantages. The observed images can appear quite blurred' and the technology requires the relative motion of the observer to expose subsequent images.

Also, there exists a number of viewing positions where more than one image is partially visible. The resultant image combinations are often meaningless and confusing. Furthermore, once a lenticular display has been created it is fixed i.e. to update the image content requires the manufacture of a complete new lenticular assembly.

Yet another technology for displaying multiple images in a single viewing frame is based around a television or computer monitor screen. The principle disadvantages to this type of technology are the comparatively high cost, limited size and poor visibility in sun-light.

An alternative technology exists, based around multi-coloured light emitting diodes, which does allow large screens to be constructed which can be used in sun-light. Unfortunately the image quality is relatively poor and the overall cost is relatively high. Although such displays are viewable in direct sun-light they consume relatively large amounts of power, have a relatively narrow viewing angle and an unnatural appearance The present invention provides a means of displaying multiple images within a single viewing frame which overcomes the drawbacks associated with the technologies already discussed.

The essential features of the invention are that two or more images are transformed into three-dimensional helixes which are then arranged in such a manner that when one image is moved in a helical path relative to the other image(s) it can be brought into view or fully obscured.

The advantages of such an arrangement are that a relatively low-power display means can be constructed which allows multiple images to be presented within a single viewing frame where each image can be of photographic quality, viewable from a wide angle, viewable in direct sunlight and capable of producing images of a natural appearance which can be alternated relatively quickly using very few moving parts.

Preferably the relative helical motion would be produced by an electrical motor although the relative motion could also be produced by another means e.g. a pneumatic actuator.

The relative helical motion could also be produced as a result of an external effect e.g. by an external magnetic field or as a result of a change in linear or angular momentum of all or part of the display.

The relative helical motion could also be produced as a result of the display changing its orientation with respect to the Earth's gravitational field.

Preferably each image would be transformed into a single threedimensional helix although displays could be produced whereby the image helixes were segmented and arranged to pass through alternate image segments at more than one point.

Preferably circular images would be used although displays could be produced using non-circular images.

The display means could form part of a larger display and be fitted behind an aperture whereby all or part of the display would be visible.

This invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows a single circular two-dimensional image being distorted into a three-dimensional helix.

Figure 2 shows a side view of two helical images axially aligned.

Figure 3 shows a two image display in operation.

Figure 4 depicts a possible means of assembling a two image circular display.

Figure 5 illustrates how segmented helixes can be used.

Figure 6 depicts a rectangular display sign with a viewing window exposing part of a helical display.

Figure 1 demonstrates how a two-dimensional circular image can be distorted into a three-dimensional helix by cutting the image along a radius, removing a circular section from the centre of the image and then stretching' the ends of the circular band thus formed in a direction perpendicular to the plane of the original image.

Figure 2 depicts a side view of two helical images of the type illustrated in figure 1 which have been axially aligned and arranged with one image in front of the other such that the image represented by the solid line is visible to the observer whereas the image represented by the broken line is completely invisible.

If the invisible image is rotated and translated such that it traces out a three- dimensional helical path it can be made to effectively pass through the slot' of the first image and move to a position in front of it. This process is illustrated by the four diagrams of figure 3.

Figure 3(a) depicts the initial view as seen by the observer ie. that of the front' image only. Figure 3(b) illustrates the leading edge of the second image traversing its helical path through the slot' of the first image and spiralling' its way into view.

Figure 3(c) depicts the situation sometime later whereby the second image has rotated through more than three-quarters of a revolution and is almost in full view.

Figure 3(d) illustrates the situation sometime after that whereby the second image has per-formed one complete revolution, is in full view and completely obscures the first image.

Figure 4 depicts one possible means of constructing a multiple image display based upon this invention. A transparent window (1), typically made of glass or clear plastic, has an opaque central region to mask the image holes' produced by the helical transformation process.

Two helical images (2) and (3) are arranged to be behind the transparent window and housed inside the body of the display (4).

The front' helical image (2) is mechanically anchored to the inner surface of the display body (4).

The rear' helical image (3) is mounted on a sleeve (5) which is supported by and travels along a threaded bar (9) which is fixed to the body of the display (4).

A gear wheel (6) is attached to the sleeve (5) which is driven by a second gear wheel (7) powered by an electric motor and gearbox arrangement (8).

The pitch of the threaded bar (9)is such that it matches the pitch of the image helixes (2) and (3). Thus when the gear wheel (6) is rotated by the action of the motor(8), which in turn rotates the sleeve (5), the rear' image helix (3) is rotated and translated in such a way as to follow a three-dimensional helical path.

This path is arranged such that it passes through the slot' in the front' helical image (2). Thus by applying one full helical rotation to the rear' image helix (3) it can be made to pass completely through the front' image helix (2) and hence becomes visible to the observer.

By simply reversing the direction of the motor, image helix (3) can be spiralled' back behind image helix (2).

Note: if a stepping motor were used to provide the movement then some form of position feedback would be necessary for the rotating image helix (3).

Typically this would be implemented using one or more optical limit switches which could monitor either the helix (3) position directly or the sleeve (5) position. For optimum performance the stepper motor would typically be accelerated and decelerated near the limits of the motion.

For the sake of simplicity the example depicted in figure 4 uses only a single rotating image helix (3). By utilising a more complicated drive arrangement and a wider helical pitch it is possible to construct a display means whereby multiple helixes can be made to move relative to each other and a fixed helix thus enabling a display means to be constructed which can display three or more images.

In a variant of the invention the image helixes can be segmented for example as shown in figure 5. This depicts a single image decomposed into three sections which are then distorted into separate helical segments.

The helical segments from different images are attached to the fixed and rotating parts of a display. Each segment has a leading edge (10) and a trailing edge (11). The leading edges (10) of an image are arranged to lie in a plane which is displaced in a perpendicular direction from a similar plane which contains the trailing edges (11).

Preferably each helical segment is oversized i.e. deliberately made longer' to provide an element of underlap and overlap. This requires that more than one copy of each image be available.

The advantage of separating each image into helical segments is that a much smaller amount of movement is required to cause one image to pass through' another. With an arrangement such as that of figure 5 only a third of a helical rotation is required.

Clearly each image could be separated into more than three segments which would then require even less movement. This arrangement could also be implemented with more than one rotating image to produce displays which could quickly change between several different images.

Although the underlying principle of the invention produces displays of a circular nature, these can be incorporated into other display means which then expose only certain parts of the display.

An example of this is shown in figure 6 where a circular multiple image display is positioned behind a fixed display (12) which has an aperture (13) which exposes only a rectangular section of the circular display. The shaded areas labelled (14) are masked from view.

Claims

Claims I A multiple image display means whereby two or more images are

transformed into three-dimensional helixes which are then arranged in such a manner that when one image is moved in a helical path relative to the other image(s) it can be brought into view or fully obscured.
2 A multiple image display means according to claim 1 whereby each image helix is separated into segments which are arranged in such a way as to allow the segments of one image to pass through the space between the segments of the other image(s) by following helical paths.
3 A multiple image display means according to claims 1 and 2 whereby the relative helical motion is produced using stepping motors which are optionally accelerated and decelerated at the limits of the motion.
4 A multiple image display according to claims 1 and 2 whereby the relative helical motion is provided as a result of a change in either angular or linear momentum induced by the acceleration or deceleration of all or part of the display means.
A multiple image display means according to claims I and 2 whereby the relative helical motion is provided as a result of a change in orientation of the display with respect to the Earth's gravitational field.
6 A multiple image display means according to claims I and 2 whereby the relative helical motion is provided as a result of a change in orientation of the

display with respect to a magnetic field.
7 A multiple image display means according to claims 1 and 2 whereby the relative helical motion is provided as the result of a change in an external

magnetic field.
8 A multiple image display means according to claims 1, 2, 3, 4, 5, 6 or 7 in which the display forms part of a larger display and is either fully visible or partially obscured.