WO2008139045A1

WO2008139045A1 - Electronically renewable image medium

Info

Publication number: WO2008139045A1
Application number: PCT/FR2008/000077
Authority: WO
Inventors: Jean-Pierre Lazzari; Jean-Marc Lazzari
Original assignee: Jean-Pierre Lazzari; Jean-Marc Lazzari
Priority date: 2007-04-27
Filing date: 2008-01-23
Publication date: 2008-11-20
Also published as: FR2915614A1

Abstract

The invention relates to an electronically renewable image medium consisting of a flexible transparent sheet (100) coated with a semi-reflective layer (101) comprising sub-pixels (102) in the three primary colours, said colours being transparent and the assembly being coated with a planarised, transparent protective layer (103). The invention is suitable for large image displays.

Description

SUPPORT OF ELECTRONICALLY RENEWABLE IMAGES

DESCRIPTION Field of application of the invention:

The present invention aims to support electronically renewable images. It finds applications including advertising screens, preferably large, installed for example in public places. The invention relates more particularly to the medium on which the electronically renewable images are made.

State of the prior art:

Advertising posters are usually printed on paper which is the most widely used substrate. Posters are stuck on a wall or sign for this purpose. Images are often printed using so-called inkjet techniques, especially for large surfaces. Once printed, the ink penetrates into the fibers of the paper, and is fixed by evaporation of the solvents that compose it. Other substrates are also used in the form of rolls, which placed inside display stands allow to expose several images, by a winding and unwinding mechanism of the rollers. These substrates must be resistant, stable, and achievable in large areas. Thus, polyester sheets coated with a special coating to facilitate the adhesion of the ink, are widely used. These displays offer an image quality far superior to paper posters, glued on a vertical support. Indeed, the transparency of the polyester substrate, allows to backlight the images which produces a high quality visual rendering. In addition, several images are presented alternately.

Despite the undeniable qualities of these displays, they nevertheless have many disadvantages. When you want to change an image, it is necessary for a maintenance technician to move, and change the rollers of the display. Upstream of this operation, important logistics are needed: image printing, storage and distribution of rolls, recycling of old rolls, which considerably increase the cost of operation of these displays. As this logistics is cumbersome and complex, this type of display does not allow to display images related to an event that has just occurred. This event display is impossible with these devices.

Thus solutions have been proposed to avoid this problem. It has been proposed to print an image, directly on the scrolling substrate, inside the display itself, using inkjet techniques. In order to renew the images, the ink does not dry, on its support, and after exposure of the image, the support is cleaned of its ink, which is eliminated. These solutions are described in particular in Japanese Patent JP6046225, JP2003337548. If the devices described by these patents have certain advantages over conventional drop-in devices, permanent image, they consume a lot of ink. The recovery of the ink, mix the colors, this which makes the recovered ink, can not be reused. The recovered ink is therefore stored in a trash tank. But the amount of ink, depending on the number of images, and the size of these images, can reach several liters per day. It is not possible to store such large amounts of ink. This problem is so difficult that patent JP2002251150 even describes a device for decomposing the ink with ultraviolet rays in order to eliminate the ink as the substrate is cleaned.

In order to avoid these drawbacks, it has been proposed to deposit, by inkjet techniques, an opaque, monochrome gel on a flat surface covered with sub-pixels in the three basic colors. The color of the sub pixels is transparent. Each sub-pixel is more or less covered with the opaque gel, depending on the amount of gel drops deposited by the ink jet nozzles, thus forming different levels of gray on each sub-pixel. The monochrome and opaque gel is recoverable and recyclable. The image obtained is of high quality. French patent application No. 06/08723 of October 5, 2006 describes such a device. While this device offers many advantages over the previous ones, the diurnal vision of the images offers a relatively poor quality because the backlit images are not very visible in full clarity. The object of the present invention is to overcome these drawbacks by proposing a new electronically renewable image medium, the image being able to be seen in full light, or backlit when the ambient light is insufficient. The support includes a transparent surface that can be rigid or flexible, coated with a first semi-reflective layer, on which sub-pixels are painted in the three basic colors, these colors being transparent. The sub-pixels are covered with a thin layer of protection, so that the recovery of the monochrome and opaque gel deposited according to the French patent application 06/08723 does not alter the sub-pixels. In a daytime and sunny atmosphere, the external light passes through the sub-pixels, crossing the surfaces not covered by the opaque gel, sub-pixels, and is reflected on the semi-transparent surface under the sub-pixels, to return towards the sub-pixels. 'observer. In a nocturnal environment, the light emitted by the light sources located at the rear of the support object of the invention, according to the previous patent application, pass through the transparent support, the semi-reflecting layer, and the sub-pixels, passing through through their surface not covered by the opaque gel.

More precisely, the subject of the invention is a medium of large and high quality renewable images in terms of resolution and number of colors, the support consisting of a transparent plane that can be rigid or flexible, which can be made of a polyester sheet for example. This support is coated with a semi-reflective layer on which are painted in the three basic colors of small repetitive surfaces called sub-pixels, the colors being transparent. Between the sub pixels, alignment patterns are evenly distributed on the support, serving to slave the position of the nozzles to inkjet, with respect to the position of the sub-pixel surfaces. Indeed, it may happen that the flexible polyester support is deformed. The projection of the opaque gel drops by the inkjet nozzles must reach precisely the sub pixels concerned, despite their misalignment induced by the deformation of the support. The sub-pixels are coated with a protective layer whose thickness is less than the smallest dimension of the sub-pixels, in order to avoid parallax problems, when the observer is not situated in front of the image. .

In any case, the features and advantages of the invention will appear better after the description which follows, given for explanatory purposes and in no way limiting. This description refers to the accompanying drawings, in which:

FIG. 1 shows in section the various layers constituting the object support of the invention.

FIG. 2 shows an enlarged section of the support object of the invention

FIG. 3 shows a plan view of the support object of the invention

Figure 1 shows a section of the support object of the invention. The base of the support (100) consists of a flexible sheet of polyester for example. Its thickness is between a few tens of microns, and a millimeter depending on the size of the image. On one of the faces of the support (100) is deposited according to the techniques known to those skilled in the art, a thin semi-reflective layer (101). On this thin layer, one prints, according to techniques known to those skilled in the art, the sub pixels (102) to the three basic colors. These colors are transparent. In the absence of the opaque gel, the surface of the support comprising the sub-pixels appears white. The sub-pixels are then coated with a transparent protective layer (103). The thickness of this protective layer is smaller than the size of the sub-pixels, in order to avoid parallax problems, if the observer is not located in the axis of the image. Its thickness is between a few microns and a few hundred microns depending on the size of the sub-pixels. The gel droplets must indeed be as close as possible to the surface of the sub-pixels. To achieve the image, the ink jet nozzles project droplets of opaque monochrome gel,

(104) that partially or completely overlap the surface of subpixels to form the gray levels. These gel droplets are projected onto the protective surface (103) of the sub pixels.

When the light level in which the observer (107) is very low, that is to say that the observer is in a dark environment, it is necessary that the image made by the droplets of opaque gel (104) is bright. To do this, light generating means (108) are located behind the support object of the invention, with respect to the surface of the sub pixels (102), and produce light rays (106) which pass through the all of the support (100), the semi-reflecting layer (101), the surface of the sub-pixels (102) and the protective layer (103). This beam appears to the observer's eye (107) with the color of the sub-pixel that it has passed through, and with an intensity proportional to the surface of the sub-pixel not covered by the gel droplets. If the surface of the sub-pixel is completely covered with gel, then a beam of light (110) from the source (108) will be stopped by the gel droplets.

When the environment in which the observer (107) is located is very bright, for example in full sun, then the ambient light (105) passes through the protective layer (103), the sub pixels (102) is reflected on the surface semi-transparent (101) and returns (111) with the color of the sub-pixel that it has crossed, with an intensity proportional to the surface not covered by the gel droplets projected on the corresponding sub-pixel. If the sub-pixel is completely covered with gel droplets, as the latter is opaque, then the incident light

(109) will not be reflected, and will be absorbed by the gel droplets.

It should be noted that the light (105) can be generated by projectors (112) which illuminate the surface of the sub pixels, which will produce the same effects as a very bright atmosphere in which the observer would be (107).

Figure 2 shows an enlarged view of the section of the support according to the invention. The transparent flexible medium (100) is coated with the semi-reflective layer (101) on which the sub pixels (102) are printed. As shown in Figure 2, the sub pixels (102), consisting of an ink layer with the basic colors, are not plane. They show a certain topography all the more important as the thickness of the ink colored used is important. As a result, if the gel droplets (104) were deposited directly on the surface of the sub pixels, the gel would penetrate the interstices of the colored surface of the subpixels.

It is therefore advisable to planarize the surface of the sub-pixels so that the gel is deposited on a perfectly flat and smooth surface, which is essential to be able to recover it without leaving a trace of gel on the surface.

The protective layer (103) is transparent, and in addition to its virtues of protecting the surface of sub-pixels plays this role of planarization. The layer (103) is deposited by coating in liquid form, on the surface of the sub-pixels, so that it penetrates well all the interstices of this surface. Thus, according to the techniques known to those skilled in the art, the viscosity, the surface tension constituting the layer (103) are optimized to obtain this result.

The layer (103) also aims to protect the surface of the sub-pixels. During the recovery of the gel, mechanical means are used, such as rubber squeegee, or rotary brush. This mechanical friction could damage the surface of the sub pixels. The physico-chemical properties of the layer (103) which may include Teflon-based components, to mechanically protect the surface of the subpixels.

Figure 3 shows a plan view of the support (100) object of the invention. The sub pixels (102) are represented by small squares uniformly distributed over the surface of the support. Projection gel droplets by the ink jet nozzles, must be relatively accurate, so that the gel is deposited in the right place in the perimeter of sub-pixels. The support (100) is flexible. It can be rolled up or unwound to bring up different images. During these movements, or localized temperature variations, the support object of the invention can undergo slight deformations. Since the ink jet nozzles are linearly guided, it may happen that the gel droplets are not directed to the right place on the surface of the subpixels. The support object of the invention comprises alignment patterns (200) uniformly distributed. These patterns can be optical, or magnetic. The inkjet nozzles are mounted on a movable platform, having sensors capable of locating the position of the sights, to position the platform supporting the ink jet nozzles precisely with respect to the alignment patterns (200) during the scanning of the screen by the ink jet nozzles despite possible deformations of the support object of the invention.

Claims

1. Image support electronically renewable by projection of an opaque gel (104) recoverable and recyclable, characterized in that the support consists of a flexible sheet (100) transparent covered on one of its faces by a semi-reflective layer (101) coated with sub pixels (102) to the three basic colors, these three colors being transparent, the sub pixels being coated with a protective layer (103).

Electronically renewable image carrier according to claim 1, characterized in that alignment patterns (200) are uniformly distributed over the surface of the support.

Electronically renewable image carrier according to claim 1, characterized in that the protective layer (103) is transparent and planarized.

Electronically renewable image carrier according to claim 3, characterized in that the protective layer (103) has a small thickness with respect to the size of the sub-pixels (102).

5. Electronically renewable image carrier according to claim 2 characterized in that the alignment patterns are magnetic or optical.

Electronically renewable image produced on the support object of the invention, according to any one of claims 1 to 5, characterized in that the light reflected by the semitransparent layer (101), or the light emitted by the source ( 108) which passes through all the layers constituting the support object of the invention, has an intensity proportional to the surface of the sub pixels not covered by the gel droplets (104) and has the color of these subpixels.