WO2005124432A1

WO2005124432A1 - Dynamic lenticular display unit

Info

Publication number: WO2005124432A1
Application number: PCT/IL2005/000613
Authority: WO
Inventors: Itzhak Bar Yona
Original assignee: Itzhak Bar Yona
Priority date: 2004-06-21
Filing date: 2005-06-09
Publication date: 2005-12-29
Also published as: IL162654A0

Abstract

A lenticular display unit for displaying consecutively changing images comprises: a complex transparent lenticular panel, comprised of two juxtaposed planar transparent panels that can be displaced relatively to one another; means for pressing the transparent panels against each other; an indicia carrier; and drive means, which cause periodic relative movement between the two juxtaposed planar transparent panels. The first of the transparent panels is a lenticular panel comprising an array of linear lenticular lenses on its front face and a planar rear face and the second of the transparent panels has smooth front and rear faces. When the indicia carrier is attached to the rear face of the second transparent panel and the drive means are activated, the lines of print of an interlaced print printed on the indicia carrier will be periodically displaced relative to the focal locus of the lenticular panel thereby causing the basic images of which the interlaced image is comprised to be consecutively displayed.

Description

DYNAMIC LENTICULAR DISPLAY UNIT

Field of the Invention The present invention relates to the field of lenticular displays. Specifically the invention is a lenticular display unit, capable of dynamically displaying multi-image presentations.

Background of the Invention Dynamic lenticular display units of various kinds are known. Such displays are used for advertising, instructional purposes and the like. The basic optical principle of displacing a complex lithographic print relative to a lenticular linear lens array, either manually or by means of a geared motor, is known from the prior art, e.g. US Patent 5.494.445 discloses general know-how for consecutively displaying several images, Japanese published patent application 02211437 by Kumagai, and US 6,226,906 by the inventor of the present invention.

In lenticular technology three basic conditions must be satisfied: 1. The information lines of the lithographic print have to be positioned in the focal points/lines of the lenses belonging to the lenticular panel. 2. The pitch distance between the information lines has to be equal to the pitch distance of the lenses of the lenticular array of lenses. 3. The information lines of the lithographic print have to be aligned with the linear lenses of the lenticular panel.

According to the method commonly used in the prior art, in order to satisfy the first condition and keep the lithographic print at the locus of the focal points of the lenses, the lenticular panel is created with a thickness equal to the focal length of the lenses. The indicia carrier, usually in a form of a printed plastic or paper sheet on which is created the printed information, is attached to the rear flat face of the lenticular panel. As a result of this arrangement, the indicia carrier remains juxtaposed to the rear flat face of the lenticular panel, i.e. — in the focal locus of the lenses, when relative movement between the indicia carrier and the lenticular panel is brought about.

While in small lenticular display units it is relatively easy to keep the indicia carrier in juxtaposed relation to the front lenticular panel this becomes more difficult to accomplish in large format display units. Practically speaking, when a large format unit, e.g. units of 1800mm by 1200mm, sometimes called "city format", with a resolution of 10 lpi (lines per inch) is created, the distance from the printed information on the indicia carrier to the focal locus can vary within a range of up to 0.2mm. If the variation is greater than this, a "ghosting effect", i.e. a partial projection of the neighboring image together with the "main image" takes place. Extruded or injected lenticular panels produced using conventional techniques have a thickness that is uniform within the above limitation; however, they are never really planar. Therefore, unless very special and expensive efforts are made in producing the sheets, when the lenticular sheet and indicia carrier are supported in parallel planes there are typically enough locations on a display of this size in which the variations in distance between print and lens exceed the allowed value to render the display useless from a commercial point-of-view. For this reason it is not possible to create large format displays using prior art display devices, such as that described in JP 02211437. The display unit taught in this publication consists of attaching the planar indicia carrier to a rigid frame and displacing it in parallel to the frontal lenticular panel. It is clear that this does not even address the problem of compensating for the deviations from a planar surface of the backside of the lenticular panel. A practical solution has been described in international patent application WO 02/23510, by the inventor of the present invention. In this application, means are disclosed for maintaining the required spatial relationship between the indicia carrier, on which the information to be displayed is printed, and the lenticular panel used to display such information: A resilient means, such as a fleece mattress supported by a rear panel, is placed such that it uniformly presses the indicia carrier against the rear face of the lenticular panel, even when relative movement occurs between them. If the indicia carrier consists of a simple plastic sheet, than the printed information, being pressed against the rear face of the lenticular panel will always be maintained at the focal distance of each and every one of the lenses, even if the lenticular panel is not perfectly planar.

Although the method of WO 02/23510 provides a practical solution to the problem of creating large format displays, this method has nevertheless several drawbacks: - A disposable plastic or paper sheet has almost no rigidity; therefore, it is very difficult to maintain its alignment with the lenticular panel while subject to constant movement. To overcome this difficulty, additional plastic lamination is applied to the printed-paper sheet, enhancing its rigidity. The increase in rigidity means that the laminated print is more resistant to the perpendicular pressure exerted on it by the fleece thereby reducing the effectiveness of the attachment of the printed information to the lenticular lens sheet. - A second drawback of the above-described method is abrasion of the printed images caused by constant friction with the lenticular panel.

In addition to estabhshing and maintaining the correct distance between the print and the lenses, there are a number of other difficulties that act together to prevent the development of practical, commercially acceptable large format dynamic lenticular display systems. Some of these difficulties are: - Since the extrusion of the lenticular panel and the printing of the indicia carrier are carried out using unrelated manufacturing processes, it is practically impossible to attain a perfect common pitch for both of them and even more difficult to establish equality of cumulative pitch distances between the lenticular panel and the printed lines of information.

- Another difficulty relates to the optical quality of the image, especially when used in ambient light. In contrast to passive lenticular display sheets, wherein the indicia carrier is bonded to the rear face of the sheet, in dynamic display units, light beams pass through an air gap created between the indicia carrier and the panel. About 20% of light emission is reflected while entering and leaving the rear face of the transparent lenticular panel. This optical loss results in viewing faint images lacking the correct color saturation. - There is a long felt need, especially by media companies, to upgrade existing passive signs into dynamic multi image ones. Attempts have been made to install lenticular display units within the light boxes of existing passive signs. Since the width of the empty space in the interior of such light boxes is sometimes limited to less than 40mm, it is quite impossible to use for this purpose a robust frame such as used to attempt to maintain the spatial relationships between the various elements of the dynamic displays made according to existing methods. It is therefore an objective of the present invention to provide a dynamic lenticular display unit, in which no constructional rigidity is required of the indicia carrier, e.g. using a simple printed-paper as an indicia carrier.

It is another objective of the present invention to provide a dynamic lenticular display unit in which the printed images suffer no abrasion as a result of the relative motion between the indicia carrier and the lenticular lens sheet. It is another objective of the present invention to provide a dynamic lenticular display unit in which the cumulative pitch distance of the print can be adapted to the cumulative pitch of the lenticular panel.

It is another objective of the invention to provide a dynamic lenticular display unit in which no air gap exists between the indicia carrier and the lenticular panel.

It is yet another objective of the present invention to provide a frameless, thick dynamic lenticular display unit, capable of being integrated into the interior of existing passive signs.

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

Summary of the Invention

In the present application, the following definitions are used: - A lenticular panel is a transparent panel with a front face comprising an array of linear lenses and a planar rear face. - A complex lenticular panel comprises two juxtaposed transparent panels pressed one against the other and capable of being displaced a hmited distance relative to each other. The front panel is a lenticular panel and the total thickness of the complex panel is essentially equal to the focal distance of the lenses. - The focal distance of a lens is the distance between the center of the frontal curved surface of the lens and the point/line of convergence of parallel light beams that pass through the lens. - The focal locus of a lenticular panel is the geometrical location of points located at the focal distance of its array of lenses. - A dynamic lenticular display unit is a display unit capable of displaying two or more alternating images. A dynamic lenticular display unit is comprised of: a lenticular front panel; an indicia carrier including a lithographic interlaced print; and drive means causing relative movement between said lenticular panel and said indicia carrier. - An interlaced print is a composed lithographic print, consisting of lines of information, received by slicing and interlacing two or more basic images. - Pitch distance of a lenses array is the distance between the centers of two adjacent lenses. - Pitch distance of an interlaced print is the distance between the centers of two adjacent information lines. - Cumulative pitch distance of a lenses array or an interlaced print is the distance between the centers of the first and the last lenses/ information lines in the array/print.

According to the present invention, a dynamic lenticular display unit is created from a complex lenticular panel; an indicia carrier, preferably in the form of a plastic or paper sheet, on which an interlaced print is created; drive means coupled to at least one of the panels of the complex lenticular panel; and guide means. The indicia carrier is attached to the rear face of the real panel of the complex lenticular panel, the drive means are activated causing a relative periodical movement between the two transparent panels, and the guide means assure the alignment of the linear lenses with the linear printed information during the motion.

In a preferred embodiment of the display unit of the invention, the air gap between the two parts of the complex lenticular panel is filled with an intermediary transparent agent, such as silicon grease, gelatin, inorganic oil, etc. The presence of this filling reduces friction and, by using a material with the proper index of refraction, can reduce, or eliminate, reflection losses at the surfaces of the panels. Similarly, using a transparent adhesive agent to attach the interlaced print to the rear face of the complex panel will reduce, or eliminate, the effects of air gap between the printed information and the panel.

As a result of its structure and its mode of operation, a display unit according to the invention has several advantages over the prior art. Specific examples of these advantages are: - Since it does not have to be constantly displaced, no rigidity requirement is placed on the indicia carrier; therefore, a simple disposable printed sheet of plastic or paper can be used. - The indicia carrier, in the form of a simple plastic or paper sheet, can be more easily aligned with the linear lenses. - No abrasion of the printed images takes place. - Since a robust constructional frame is not necessary to support the indicia carrier relative to the lens sheet, the display unit of the invention can easily be installed in passive signs, upgrading their ability to display "eye catching" moving images. Since the air gaps in the prior art systems have been eliminated, the colors of the basic images are more "alive. The invention is a lenticular display unit for displaying consecutively changing images comprising: (a) a complex transparent lenticular panel, comprised of two juxtaposed planar transparent panels, the transparent panels being capable of being displaced relatively to one another; (b) means for pressing the transparent panels against each other while permitting limited relative movement between them; (c) an indicia carrier; and (d) drive means causing periodic relative movement between the two juxtaposed planar transparent panels.

The first of the transparent panels is a lenticular panel comprising an array of linear lenticular lenses on its front face and a planar rear face and the second of the transparent panels has smooth front and rear faces. When the indicia carrier is attached to the rear face of the second transparent panel and the drive means are activated, the lines of print of an interlaced print printed on the indicia carrier will be periodically displaced relative to the focal locus of the lenticular panel. This periodic displacement will cause the basic images of which the interlaced image is comprised to be consecutively displayed.

In the preferred embodiment of the lenticular display unit of the invention, the combined thickness of the two planar transparent panels is essentially equal to the focal length of a lens belonging to the array of lenses. Embodiments of the lenticular display comprise guiding means for maintaining the alignment between the juxtaposed planar panels when they are in motion.

In preferred embodiments of the lenticular display unit of the invention, the print on the indicia carrier is aligned with the lenses on the lenticular panel by means of pins, which fit into holes in the second transparent panel and protrude from its rear face. For large format embodiments of the lenticular display unit the indicia carrier is divided into two or more sections. A transparent liquid or gel preferably fills the gap between the two juxtaposed panels and the indicia carrier is preferably attached to the rear face of the second transparent panel by means of a transparent pressure sensitive adhesive.

In another aspect the invention is a billboard comprised of a large light box, a plurality of lenticular display units of the invention, and synchronization means. Each of the lenticular display units projects a part of the entire image to be displayed and the synchronization means enable the plurality of lenticular display units to act in unison, thereby projecting gigantic images spread over the entire billboard.

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. With specific reference now to the figures in detail, it is stressed that no attempt has been made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Brief Description of the Drawings

- Fig. 1 is a front perspective view of a display unit, according to the invention; - Fig. 2A is a rear view of the unit shown in Fig. 1; - Fig. 2B shows in enlarged detail an area of Fig. 2A;

- Fig. 3 is a vertical cross section of the unit shown in Fig 1;

- Fig. 4 and Fig. 5 are enlarged details of Fig. 3;

- Fig. 6 shows a passive sign installed in a bus-stop station; and - Fig 7 shows how the passive sign of Fig.6 can be retrofitted with a dynamic display unit of the invention.

Detailed Description of Preferred Embodiments

Fig. 1 and Fig. 2A are perspective views showing respectively the front and rear of a display unit 10, according to the invention. The unit 10 includes a complex lenticular panel 12, consisting of two planar transparent panels, a front lenticular panel 14 and a rear complementary flat panel 16, held together by pressing means 18, which can be for example plastic transparent pins or screws. In Fig. 2B, which shows in enlarged detail area 20 of Fig. 2A, it can be seen how the pin passes through a linear slot 22 in flat panel 16, in order to be firmly fixed to frontal panel 14. Several pressing means 18 are spread over the entire area of the panels 14 and 16. They are designed to hold the two panels in juxtaposed relationship, while still being permitted a limited displacement in a vertical direction. In the cross sectional detail of Fig 5 it can be seen how the fastening means passes through slot 22 in flat panel 16 and penetrates front panel 14 to which it is fixedly attached by suitable means such as friction, glue, or self-tapping threads.

Returning to Fig. 2A, geared motor 24 is responsible for the periodical displacement of panel 16 relatively to lenticular panel 14. In this figure, motor 24 is shown connected to battery 26, but in other embodiments another power source such as mains current or solar energy could be used to activate the motor. Indicia carrier 28 in a form of disposable plastic or paper sheet is attached to the rear face of panel 16 by adhesive means, in a way that it can easily be replaced with each new advertising campaign. In order to accurately align the printed linear information of indicia carrier 28 with linear lenses 30 of lenticular panel 14, the back panel 16 of complex lenticular panel 12 has at least two pins in it that project out of the rear face of panel 16. These pins are very accurately located with respect to the linear lenses on the front side of lenticular panel 14 of complex lenticular panel 12. Each indicia carrier 28 has at least two holes (punctures) 32 in locations that match the locations of the pins. The holes 32 are made as a part of the printing process on the indicia carrier to insure proper alignment with the lines of print. To attach the indicia carrier 28 to the back of panel 16, the holes 32 in the indicia carrier 28 are slipped over the corresponding pins 34, thereby aligning the print with the lenses.

A more detailed understanding of the manner in which the relative motion between the print and lens is achieved unit can be attained with reference to Fig. 3, which is a cross section of display unit 10, taken along a line vertical line passing through the motor 24. From the figure and especially with reference to Fig. 4, which shows an enlarged view of area 36 of Fig. 3, it can be seen how lenticular panel 14, juxtaposed to flat panel 16 is periodically displaced by rotation of eccentric cam 38, which is coupled to the shaft 40 of geared motor 24. The motor 24 is shown attached to flat panel 16 by means of screws 42.

The optical relationships between the different parts constituting display unit 10 are described with reference to Fig. 5, which shows an enlarged view of area 44 in Fig. 3. Thickness "t" of lenticular panel 14 added to thickness "s" of flat panel 16 equals the focal distance "f ' of lens 30, i.e. f = s+t. The printing of the interlaced image on the indicia carrier 28 is in the form of lines of width M, which are equal to the width of each of the linear lenses 30. Each of the lines of print are subdivided into sub-lines corresponding to each of the basic images. In the example shown in Fig. 5, there are three basic images "A", "B", and "C". When the center of the lens is lined up essentially opposite to one the sub-lines, then light beams representing information line "B", pass through both panels 1 and 2 and are magnified and seen as image "B". This is true for all of the lenses and the result is that the basic image "B" displayed to the viewer. When lenticular panel 14 is displaced relative to flat panel 16 with indicia carrier 28 attached to it, then basic images "A", "B", and "C" are alternatively displayed. Air gap 13, between panels 14 and 16, is preferably filled with a transparent liquid or jell whose index of refraction is substantially equal to those of the material from which the two panels are formed. In this way two advantages are achieved: firstly, reduction of the friction between the two panels sliding back and forth over each and secondly reducing light loss by reflection at the interface between the air gap and the panels. In order to avoid the occurrence of a second air gap between panel 16 and indicia carrier 28, the means for attaching them together can be selected from a variety of transparent pressure sensitive adhesives so that the indicia carrier can be easily and cleanly removed and replaced for subsequent advertising campaigns.

Fig. 6 shows a bus-stop station 48 comprising two passive advertising signs 50. The procedure for retrofitting the static signs 50 with lenticular dynamic display unit of the invention for displaying changing images is described with reference to Fig. 7. Sign 50 is generally constructed of a basic light box 52 containing the fluorescent bulbs 54 with its electric system 56. A hinged door 58 can be opened to permit access to the interior of sign 50. A lenticular display unit 60 of the invention is built in such a way as to enable it to be removably installed onto winged door 58. Display 60 consists of complex lenticular panel 12, such as that described with reference to Fig. 1, but in this case having vertical linear lenses. A lightweight frame 64, with clasps 66 serves to install panel 62 to the metal frame 68 of hinged door 58. Frame 64 also functions as guiding means for maintaining the alignment between the juxtaposed planar panels of complex panel 12 when they are in motion and also for pressing them against each other. Drive means 70, similar to those described hereinabove, are attached to frame 64, for example by means of bracket 72. The drive means 70 may be actuated by a battery, but preferably are connected to the electric system of sign 50, in order to bring about the required movement between the two constituents of complex panel 12.

Lithographic printing on the indicia carrier is a very accurate and reproducible process and any number of interchangeable indicia carriers of any size having identical cumulative pitches can be easily produced. On the other hand, plastic extrusion in large formats is never really accurate and the cumulative pitches of large lenticular panels produced by this method typically vary slightly from the nominal values. One method of overcoming the difficulty caused by lack of a perfect common pitch for both the lenticular panel and the printing of the indicia carrier and to establish equality of cumulative pitch distances between the lenticular panel and the printed lines of information is to print a customized print for each lenticular panel; however, this is not a commercially viable solution.

The present invention solves the problem of matching the cumulative pitch differences for large format display units by dividing the indicia carrier into two or more sections. The indicia carrier is made from a material such as plastic that is slightly elastic. The printing is done on the lenticular carrier using a pitch distance slightly less than the nominal pitch distance of the lenses. Each section of the indicia carrier is then stretched and supported over the appropriate section of the lenticular panel as will be described hereinbelow. In this way the difference in the cumulative pitch of the lenses from that of the print is compensated for over each part of the lens sheet separately before the difference becomes large enough to cause ghosting.

In a large format display, such as the display unit 60 shown in Fig. 7, the indicia carrier comprises two or more separate indicia carriers 28 made of plastic sheets. Each of the indicia carriers 28 has an array of holes 32, made in predetermined places to match a similar array of holes made in complex lenticular panel 12. The holes 32 are made as a part of the printing process on the indicia carrier to insure proper alignment of the lines of print with the alignment holes 32. To attach the indicia carrier 28 to the back of panel 16, the holes 32 in the indicia carrier 28 are slipped over pins 34 that protrude from the back side of the back of panel 16. Pins 34 are precisely located with respect to the lenses and are arranged in an array corresponding to that of holes 32 in the indicia carrier. Each of the separate pieces of the indicia carrier is attached separately to the back of the flat panel in this manner. Activating the drive means 70 will cause a relative displacement of the two panels of complex lenticular panel 12 and therefore the information of the indicia carrier will be accurately displaced as a whole relative to the lenses.

The final result of dividing the indicia carrier is equivalent to using a single indicia carrier. Slight discontinuities may appear along the boundary between the sections of the indicia carriers 28; however, the effect of this discontinuity on the quality of the images displayed is typically virtually unnoticeable and is orders of magnitude less serious than the problem of the total cumulative pitch, which has been solved. In Fig. 7, the indicia carrier was shown as divided into two sections for clarity. In reality, the number of sections of indicia carrier that will lead to the optimal results depends on a number of factors. The most critical of these factors is the known or predicted difference between the cumulative pitch difference of the lenticular sheet and the printing. Other factors include, but are not limited to the size of the display, the desired quality of the images, and economic issues related to, for example, replacement time of the indicia carrier and production of several indicia carriers as opposed to a single one.

It is to be noted that in the display unit 60 shown in Fig. 7, the clasps 66, allow the unit to be easily attached and removed from the frame 68 of the door 58 of advertising sign 50. This allows the unit 60 to be replaced in its entirety with a new one comprising a different interlaced image and the old unit can be returned to the workshop, where the indicia carrier can be replaced in a more suitable working environment than in the field.

It is also to be noted that the functioning of a lenticular display unit, such as that described in Fig. 7 does not depend on the existence of the lightweight frame 64. The plurality of pressing means spread over the surface of the display is sufficient to maintain the relationship between the lenticular panel and the rear panel. Therefore the unit can consist of a complex panel only, without any supporting frame. Such embodiments can be used to retrofit static display units wherein the available space is only about 10mm. Is such a case, the complex panel is hung on the front door of the static display unit exactly like the simple, static poster is hung and can be easily removed when the owner of the media wishes to change dynamic displays or revert to the use of static posters again.

The unit according to the invention can be cut to measure to be installed in any light box. If a large light box is to be used, then a plurality of modular units can be installed, each one projecting a part of the entire image. Synchronization means can be added to the numerous modular units, so as enable them to act in unison and thereby project gigantic images spread over the entire billboard.

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.

Claims

1. A lenticular display unit for displaying consecutively changing images comprising: (a) a complex transparent lenticular panel, comprised of two juxtaposed planar transparent panels, said transparent panels being capable of being displaced relatively to one another; (b) means for pressing said transparent panels against each other while permitting limited relative movement between them; (c) an indicia carrier; and (d) drive means causing periodic relative movement between said two juxtaposed planar transparent panels; wherein, the first of said transparent panels is a lenticular panel comprising an array of linear lenticular lenses on its front face and a planar rear face and the second of said transparent panels has smooth front and rear faces; whereby, when said indicia carrier is attached to the rear face of said second transparent panel and said drive means are activated, the lines of print of an interlaced print printed on said indicia carrier will be periodically displaced relative to the focal locus of said lenticular panel, thereby causing the basic images of which said interlaced image is comprised to be consecutively displayed.

2. A lenticular display unit as claimed in claim 1, wherein the combined thickness of the two planar transparent panels is essentially equal to the focal length of a lens belonging to the array of lenses.

3. A lenticular display unit as claimed in claim 1, comprising guiding means for maintaining the alignment between the juxtaposed planar panels when they are in motion.

4. A lenticular display unit, according to claim 1, wherein the print on the indicia carrier is aligned with the lenses on the lenticular panel by means of pins, which fit into holes in said second transparent panel and protrude from its rear face.

5. A lenticular display unit, according to claim 1, wherein the indicia carrier is divided into two or more sections.

6. A lenticular display unit, according to claim 1, wherein a transparent liquid or gel fills the gap between the two juxtaposed panels.

7. A lenticular display, according to claim 1, wherein the indicia carrier is attached to the rear face of the second transparent panel by means of a transparent pressure sensitive adhesive.

8. A billboard comprised of: (a) a large light box; (b) a plurality of lenticular display units as claimed in claim 1; and (c) synchronization means; wherein, each of said lenticular display units projects a part of the entire image to be displayed and said synchronization means enable said plurality of lenticular display units to act in unison, thereby projecting gigantic images spread over said entire billboard.