WO2003077228A1

WO2003077228A1 - Stretchable indicia carrier film and support system

Info

Publication number: WO2003077228A1
Application number: PCT/IL2002/000194
Authority: WO
Inventors: Itzchak Bar-Yona
Original assignee: M.V.T. Multi Vision Technologies Ltd.
Priority date: 2002-03-11
Filing date: 2002-03-11
Publication date: 2003-09-18
Also published as: AU2002236191A1

Abstract

The invention is a dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions. The display unit comprises a front lenticular panel comprising an array of lenses and a stretchable indicia carrier placed behind the rear side of the front panel. The unit also comprises means for rigidly engaging the edges of the indicia carrier, means for stretching the indicia carrier tightly over the entire rear side of the front panel, and means for displacing the indicia carrier relative to the lenses on the front panel without allowing the indicia carrier to stretch or contract relative to the front panel. The indicia carrier has a stretchable substrate having elastic properties and the indicia are printed on the substrate. The lines of printing initially have a pitch distance slightly less than the pitch distance of the lenses of the array on the front lenticular panel and can be made equal to the pitch distance of the lenticular panel by applying an external force to stretch the substrate.

Description

P T/IL02/00194

STEETCHABLE INDICIA CARRIER FILM AND SUPPORT

SYSTEM

Field of the Invention

The present invention relates to the field of display units, which provide a multi-image presentation for advertising, information, or decoration purposes. Specifically the invention relates to an indicia carrier in the form of a stretchable material containing the material to be displayed and to a system for supporting the indicia carrier.

BACKGROUND of the Invention

Lenticular technology, in particular as applied to known dynamic display units, requires accurate relationships between the lithographic print and the frontal lenticular panel. Three basic optical conditions must be maintained:

1. Complete alignment between the printed lines on the indicia carrier and the linear lenses of the front panel must exist.

2. Constant spacing, essentially equal to the focal length of the lenses, between the printed information and the lenticular panel is required. 3. The "cumulative pitch distance" for the array of linear lenses and for the printed lines on the indicia carrier must be equal at all times.

The term "pitch distance" refers to the distance between the centers of two adjacent lenses or two adjacent lines of print. "Cumulative pitch distance" is the sum of the pitch distances for all the lenses or lines of print, i.e. the distance between the centers of the first and last lenses of a given panel, or between the centers of the first and last lines of print on a given indicia carrier.

The third condition is difficult to satisfy because of three major factors:

1. inconsistency of the printing process;

2. inexactitude of plastic manufacturing processes; and

3. differences in the thermal coefficients of the indicia carrier substrate and the lenticular panel.

In regular printed cards based on lenticular technology the printed information is applied directly on the rear side of the film partially alleviating the difficulties listed above. In dynamic display units, however, the indicia carrier is printed separately and is inserted into the display unit and replaced with a different, indicia carrier according to the display needs. Under these circumstances, quality control of the printing and plastic injection (or extrusion) processes alone cannot satisfy the requirements for the cumulative pitch distance.

The problem of cumulative pitch distance is illustrated in Figs. 1A and IB, which schematically show front and cross-sectional views of a typical lenticular dynamic display unit. Such a display unit is described in US Patent 6,226,906 and South African patent 2000/331, by the same inventor, the descriptions of which are incorporated herein by reference.

The display unit 1 consists of a rigid frame 2 and a planar lenticular panel 3, comprising an array of linear lenses 4. Mounted behind panel 3 is an indicia carrier 5. On the indicia carrier is printed, according to the know- how of lenticular technology as known for example from US 6,226,906, an interlaced image comprised of three separate images A, B, and C. In order to view the different images, the observer looks at the display from a fixed angle and different parts of the interlaced image are brought in front of the lenses by vertical displacement of the indicia carrier relative to the panel. This displacement is achieved by means of motor 6 which turns the eccentric cam 7 to which the indicia carrier is attached. Note that, in this case, the condition of alignment is satisfied if the lenses and the lines of print are parallel to one another over the whole area of the display.

Figs. 1A and IB are divided by wavy lines 8 and 9 into three sections showing different displacements of the indicia carrier relative to the lens panel. At the bottom of the figures (below line 9), the information in the interlaced image related to image B is positioned exactly at the focal point of the lenses. At this position, assuming that the same condition is met for all of the lenses, the observer sees image B. At the top of the figures (above line 8), the indicia carrier has moved down a distance exactly equal to the pitch distance of the lenses and in this case the observer sees image A. In the middle section, the motion is less than the pitch of the lenses and two images will be projected at the same time, an effect known as "ghosting".

In the above discussion, it was assumed that the pitch distance of the lenses and the lines of printing comprising the interlaced image were the same and that the ghosting was the result of physical displacement. It is clear however that any cause of difference between the pitch of the lenses and the printing will result in the same effect. .

As discussed above one of the factors that cause a difference in the pitch is the. different thermal expansion coefficients of the materials of which the components are made. The problem presented by thermal expansion is difficult to overcome, especially for large format display units exposed to outdoor conditions. To illustrate the order of magnitude of the problem of thermal expansion, consider an Al standard format display unit with a lenticular panel having a nominal six lenses per inch. The panel has 150 lenses with a pitch distance of 4.0mm. Its initial cumulative pitch distance is 600mm at 23°C. On exposure to an outdoor temperature of 30°C it expands to 601.1mm. The indicia carrier of the unit, under the same temperature changes, expands to only 600.5mm, if it is made of polycarbonate film, and shrinks to 599.5mm, if it is made of laminated paper film. The difference between the change in the cumulative pitch distance of the indicia carrier and that of the lens panel amounts to 0.6m or 1.6mm, depending on the material of the film. If the print comprises four images, then the basic printed line has a width of 1.0mm and it is obvious that under these conditions the temperature induced difference in cumulative pitch distances results in a "ghosting effect".

It is therefore a purpose of the present invention to provide a dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions.

It is another purpose to provide a stretchable indicia carrier for a dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions.

It is a further purpose of the present invention to provide a support system for the indicia carrier of a dynamic display unit that will allow the cumulative pitch distance of the printing on the indicia carrier to be made equal to that of the lenticular panel and to maintain that equality under all operating conditions.

Further purposes and advantages of this invention will appear as the description proceeds.

Summary of the Invention

In a first aspect the present invention is directed towards providing a dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions. The display unit of the invention comprises: a. a front lenticular panel comprising an array of lenses; b. a stretchable indicia carrier placed behind the rear side of the front panel; c. means for rigidly engaging the edges of the indicia carrier; d. means for stretching the indicia carrier tightly over the entire rear side of the front panel; and e. means for displacing the indicia carrier relative to the lenses on the front panel without allowing the indicia carrier to stretch or contract relative to the front panel. In a preferred embodiment of the invention, the front lenticular panel of the display unit is a curved panel, with the convex side towards the back of the display unit.

In another aspect the present invention is directed towards providing a stretchable indicia carrier for a dynamic display unit comprising a front lenticular panel and further comprising: a. a stretchable substrate having elastic properties; and b. indicia printed on the substrate, wherein the lines of printing initially have a pitch distance slightly less than the pitch distance of the lenses of the array on the front lenticular panel and can be made equal to the pitch distance of the lenticular panel by applying an external force to stretch the substrate.

In yet another aspect the present invention is directed toward providing a method for providing a dynamic display using a dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions. The method comprising: a. providing a front lenticular panel comprising an array of lenses; b. placing a stretchable indicia carrier behind the rear side of the front panel; c. rigidly engaging the edges of the indicia carrier by suitable means to suitable members of the frame of the display unit ; d. stretching the indicia carrier tightly over the entire back side of the front panel by using suitable means; and e. displacing, by use of suitable means, the indicia carrier relative to the lenses on the front panel without allowing the indicia carrier to stretch or contract and while keeping the indicia carrier tightly stretched over the entire concave side of the front panel.

All the above and other characteristics and advantages of the invention will be further understood through the following illustrative and non- limitative description of preferred embodiments thereof, with reference to the appended drawings.

Brief Description of the Drawings

- Figs. 1A and IB schematically show front and cross-sectional views of a typical lenticular dynamic display unit;

- Fig. 2 is a schematic view of an outdoor installation of a dynamic display unit according to a preferred embodiment of the invention; Figs. 3A, 3B, and 3C are respectively schematic front, horizontal cross-sectional, and enlarged views showing details of the structure of the display unit of Fig. 2; - Fig. 4A shows how the indicia carrier film is attached to the rotating shaft;

- Figs. 4B and 4C disclose more details of the display unit of the embodiment of Fig. 2;

- Fig. 5 shows a large dynamic display billboard according to a preferred embodiment of the invention;

- Fig. 6 shows the constructional details of the internal frame of the billboard of Fig. 5;

- Fig. 7A shows the frame of Fig. 6 with the lenticular lenses in place;

- Figs. 7B and 7C are respectively enlarged views of areas of Fig. 7A; and

- Figs. 8A and 8B show the method of supporting the indicia carrier and achieving and maintaining the proper relationship between the lenses and print for the billboard of Fig.5.

Detailed Description of Preferred Embodiments

Definitions:

In this application:

1. the terms "sign" and "display unit" are used interchangeably to refer to display units based on lenticular technology;

2. the terms "large size" and "large format" are used interchangeably and refer to size, of about, A2 (320mm x 400mm) or larger; and 3. the terms "sheet", "film", and "indicia carrier" are used interchangeably to refer to any flexible surface onto which information can be printed, including, but not limited to, paper sheets, polymeric films, and layered composite materials.

Fig. 2 is a schematic view of an outdoor installation comprising several dynamic display units according to a preferred embodiment of the invention. The dynamic display unit 21 consists of a rigid frame 22 and a large format curved lenticular panel 23 comprising an array of vertical linear lenses. The lenticular panel can be planar. However a curved panel, with the convex side towards the back of the display unit, is preferred. This is because, as will be clear from the description below, it is easier to maintain the correct spatial relationship between the lenses and the indicia if the film is stretched over the convex surface. In practice the amount of curvature doesn't have to be large. In a typical example, the width of the panel is 100cm and the height of the center of the panel relative to the edges is 2-3cm.

Figs. 3A, 3B, and 3C are respectively schematic front, horizontal cross- sectional and enlarged views showing details of the structure of the display unit of Fig. 2. Fig. 3B is a cross-section taken along line AA in Fig. 3A and Fig. 3C shows area 32 of Fig. 3B. In Fig. 3A the lenticular panel 23 and the external frame composed of vertical profiles 27 and horizontal profiles 28 are seen.

In Fig. 3B is seen a curved lenticular panel 23 spread over an internal metal frame 26. The indicia carrier 25, in the form of a stretchable film, is stretched over the convex back surface of the panel and is attached to two vertical rotatable shafts 24. The shafts are located in vertical profiles 27 of the outer frame of the unit and can be simultaneously rotated, as indicated by double-headed arrow 31 in Fig. 3C, to displace indicia carrier 25 relative to the lens of lenticular panel 23 as indicated by double headed arrow 30. A linear groove is created along the length of each shaft 24 into which the end of the indicia carrier film is inserted for engaging the shaft by means of a complimentary profile 29.

Fig. 4A shows how the indicia carrier film is attached to the shaft. Both the edge of the film and the complementary profile 29 contain a number of previously created holes 35 that are used, with the aid of pins 34, to precisely locate the film. After the film is placed over the pins in the groove, the complementary profile is inserted in the grove to lock the edge of the indicia carrier firmly to the vertical rotating shaft.

Figs. 4B and 4C show more details of the display unit of Fig. 2. Fig. 4B is a rear view of the unit and Fig. 4C is a magnified view of area 33 of Fig. 4B. In these figures, it is seen that the ends of the shafts 24 are connected to the ends of horizontal profile 28. Mounted on the horizontal profile is geared motor 36 which represents any suitable mechanism for causing the vertical rotating shafts 24 to simultaneously rotate, thus causing the indicia carrier to be displaced relative to the lenticular lens and alternately revealing the separate images contained in the interlaced image to the observer. A suitable mechanism for causing the rotation can easily be devised by the skilled person. Such a mechanism can comprise, for example, an arrangement of gears, belts, cables, pulleys, or any combination of these, suitably linked to the motor.

According to the interlacing method of the prior art, the pitch distance of the printed lines and the linear lenses is equal. In contrast to the situation in the prior art, in all embodiments of the present invention the pitch distance of the printed fines is slightly less than that of the lenses. In the present context, "slightly less" means that the cumulative pitch distance of the printing on the unstretched substrate is approximately 2- 10mm or essentially equal to the pitch distance of the lenses. In other words, the indicia is printed on the substrate such that the cumulative pitch distance of the lenticular array is greater than that of the printing on the unstretched indicia carrier by a distance equal to the width of one of the lenses.

An illustrative example of the method of determining the pitch distance of the printing, according to the present invention, will now be given. If a panel such as 23 of Fig. 3A comprises 300 lenses with a nominal pitch distance of 4.0 mm, then the theoretical cumulative pitch distance is D = 300 x 4.0 = 1200mm. It is known that D may vary by ±l.δmm. Therefore, if the interlacing software is supplied with a value for the line width of M = 3.993mm, the cumulative pitch distance for the printing will be equal to 1198mm. Upon being stretched, the film will cover the range,, of 1200±1.5mm as required.

The indicia carrier is now attached to the vertical rotating shaft as described above. At this stage, it will not be tightly stretched over the entire surface of the lenticular sheet. Referring to Figs. 4B and 4C, a lever 37 can be seen attached to the horizontal profile 28. Lever 37 represents any suitable mechanism for causing slideable extension profile 38 to move such as to effectively change the length of profile 28. A similar extension profile is attached to the lower horizontal profile and it should be noted that the ends of the on of the shafts 24 are connected to the extension profiles. Extension profile 38 can be attached to profile 28 by any suitable means, for example by use of a dovetail joint. The skilled person will be easily able to device a suitable mechanism for changing the length of the horizontal profile, the mechanism must be able to simultaneously cause essentially the same change in length of both the top and the bottom horizontal profiles. Thus, by using the mechanism represented by lever 37, the upper and lower profiles 28 are lengthened. Since the ends of the vertical rotating shafts are attached to the ends of profiles 28, the shafts will be moved apart and the attached indicia carrier will be tightly stretched over the entire surface of the lenticular sheet. The stretching is carried out until the cumulative pitch distance of the printing equals that of the lenses. When this condition is met, then the mechanism represented by the lever is locked by a suitable locking mechanism 39 to prevent any further movement of slidable extension profile 38 relative to profile 28.

In this embodiment, the film is stretched directly on the back surface of the panel which is of a thickness essentially equal to the focal length of the lenses, thus assuring the required distance between the printed lines and the lenses.

The substrate chosen for the indicia carrier must retain its elastic properties, being able to repeatedly return to its original dimensions when stretched over the range of several mm per meter of length. The substrate must also be sufficiently strong to resist tearing while stretched. As an example of the force involved, for one display unit a force of approximately 8 Newtons/cm was applied to the edge of the substrate in order to stretch it 4mm. Suitable substrate materials are commercially available from, for example, PPG Industries (Teslin® synthetic printing sheet) and Neschen Company (Printlux WP, synthetic paper). In the dynamic display units of the invention, ghosting caused by inconsistency of the printing process and inexactitude of plastic manufacturing processes are compensated for by the initial stretching of the indicia carrier and ghosting caused by changes in the ambient temperature of the unit is essentially non-existent because the curved shape of the lenticular panel. When changes in temperature cause the plastic lenticular panel to expand or contract, relative to the metal frame, the radius of curvature of the panel tends to change accordingly. Because of the way in which the elastic print is stretched over the panel the print shrinks or expands to adjust to the new dimensions of the panel and thus the coherence between the printed information and the array of lens is maintained.

As one example of the effectiveness of the present invention a trial was carried out using a dynamic display unit essentially similar to that shown in Fig. 2 having a synthetic paper indicia carrier. It was found that no ghosting was observed in a controlled temperature environment when the temperature was changed over a range of minus 20°C to plus 40°C.

Fig. 5 shows a large dynamic display billboard according to a preferred embodiment of the invention. Visible in the figure is the external metal frame 51 and the curved transparent front screen 52 comprising an array of lenticular lenses. The lenses 53 of the array are horizontal linear lenses. Fig. 6 shows the constructional details of the internal frame of the billboard of Fig. 5. The frame consists of modular vertical segments 61 connected by horizontal beams 62. The vertical segments support two parallel horizontal rotating shafts 63, located at the top and the bottom of the front of the billboard. A vertical metal rod 64 connects the two shafts 63 and causes them to rotate simultaneously in the same direction when it is displaced upwards and downwards. A geared motor 65, mounted on the frame of the billboard is the means used to cause vertical displacement of the rod 64.

Fig. 7A shows the frame of Fig. 6 with the lenticular lenses 53 in place. Figs. 7B and 7C are respectively enlarged views of areas 67 and 68 in Fig. 7A. An additional feature schematically shown in Fig. 7A is the expander/contractor device 66 that is used to change the length of vertical metal rod 64. The simplest, and preferred, embodiment of device 66 is a turnbuckle although any suitable arrangement that can be devised by the skilled person to accomplish the stated purpose may be used.

Figs. 8A and 8B show the method of supporting the indicia carrier and achieving and maintaining the proper relationship between the lenses and print. The indicia carrier film 81 is attached to the frame with the aid of a profile 82 one of which is attached to both of the horizontal rotating shafts 63. Profile 82 has a longitudinal recess 83 into which complimentary profile 84 fits to lock the film firmly in place. Both the edge of the film and the complementary profile contain a number of previously created holes that are used, with the aid of pins located in the longitudinal recess, to precisely locate the film. Neither the holes nor the pins are shown in Figs. 8A or 8B.

The method of connecting an indicia carrier into the billboard will now be summarized. The indicia carrier is in the form of a stretchable film having the same characteristics as the film described herein above. Firstly the film is inserted on the back (convex) side of the front panel and connected to the profiles at the top and bottom of the billboard. Then (see Fig. 7A) the device 66 is used to change the length of vertical metal rod 64, such that the rotation (in opposite directions) of horizontal rotating shafts 63 will cause the film to be stretched. The stretching continues until the cumulative pitch distance of the film is equal to that of the array of lenses. The lines of print can now be displaced relative to the lens by operating the geared motor 65 connected to rod 64 which causes the rod to move up and down rotating (in the same direction) the horizontal rotating shafts 63. Rotation of the shafts alternately clockwise and counter-clockwise causes the film attached to them to move up and down relative to the fixed lenses.

In order to maintain the correct distance between the indicia carrier and the lenses, linear ribs 85 are formed on the rear side of the front panel 52. As will be appreciated by the skilled person, in the case of a large billboard it is not possible to construct the front screen in one piece. In Fig. 8B can be seen the solution to this problem. The front screen actually comprises a number of profiles, which are carefully positioned one above the other, very carefully aligned, and attached to the frame. In the billboard of Fig. 8B, each profile comprises eight lenses 53 and two linear ribs 85.

For the same reason described hereinabove, changes in temperature do not result in ghosting effects in this embodiment of the invention.

Although embodiments of the invention have been described by way of illustration, it will be understood that the invention may be carried out with many variations, modifications, and adaptations, without departing from its spirit or exceeding the scope of the claims. In particular it should be noted that, in the embodiments described hereinabove, the lenses are static and the indicia carrier moves relative to them. The skilled person will know how to make a dynamic display system in which the lens panel moves relative to a stationary indicia carrier.

Claims

1. A dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions comprising: a. a front lenticular panel comprising an array of lenses; b. a stretchable indicia carrier placed behind the rear side of said front panel; c. means for rigidly engaging the edges of said indicia carrier; d. means for stretching said indicia carrier tightly over the entire rear side of said front panel; and e. means for displacing said indicia carrier relative to said lenses on said front panel without allowing said indicia carrier to stretch or contract relative to said front panel.

2. A dynamic display unit according to claim 1, wherein the front lenticular panel of the display unit is a curved panel, with the convex side towards the back of the display unit.

3. A stretchable indicia carrier for a dynamic display unit comprising a front lenticular panel and further comprising: a. a stretchable substrate having elastic properties; and b. indicia printed on said substrate, wherein the lines of printing initially have a pitch distance slightly less than the pitch distance of the lenses of the array on said front lenticular panel and can be made equal to said pitch distance of said lenticular panel by applying an external force to stretch said substrate.

A stretchable indicia carrier for a dynamic display unit, wherein the front lenticular panel of the display unit is a curved panel, with the convex side towards the back of the display unit.

A method for providing a dynamic display using a dynamic display unit in which the cumulative pitch distance of the printing on the indicia carrier is equal to that of the lenticular panel under all operating conditions comprising: a. providing a front lenticular panel comprising an array of lenses; b. placing a stretchable indicia carrier behind the rear side of said front panel; c. rigidly engaging the edges of said indicia carrier by suitable means to suitable members of the frame of said display unit ; d. stretching said indicia carrier tightly over the entire back side of said front panel by using suitable means; and e. displacing, by use of suitable means, said indicia carrier relative to said lenses on said front panel without allowing said indicia carrier to stretch or contract and while keeping said indicia carrier tightly stretched over the entire concave side of said front panel.

method for providing a dynamic display using a dynamic display unit according to claim 5, wherein the front lenticular panel of the display unit is a curved panel, with the convex side towards the back of the display unit.