WO2003015329A2 - Photosensitive device for internal information transfer and information coding process - Google Patents

Abstract

The invention refers to a photosensitive device with typical appearance similar to a post office stamp, provided with information and equipped with at least two internal layers, able to perform the information transfer, be it coded or not, from one layer to another, activated by an appropriate light stimulus. Furthermore, the invention refers to an information coding process, which the result is an image whose features (shape, intensity, etc.) are useful when associated to the occurrence of an event and its duration, e.g. proof of the broadcasting of a specific television program within a given time period.

Description

PHOTOSENSITIVE DEVICE FOR INTERNAL INFORMATION TRANSFER AND INFORMATION CODING PROCESS

DISCLOSURE OF THE INVENTION

The invention refers to a photosensitive device which is able to perform information transfer from an internal layer to another.

More specifically, it refers to a photosensitive device with typical appearance similar to a stamp, provided with information and comprising at least two internal layers, able to perform information transfer, be it coded or not, from one layer to another, activated by an appropriate light stimulus. FIELD OF THE INVENTION

A particular use of the invention, not excluding any other, is related to the fidelity of spectator audience, as evaluated according to the time when a given program is broadcast and registered by the device of the invention.

PRIOR ART Two references can be mentioned as representative of the state of the art for this application. The first one is the German Patent Application DE 4,312,185, issued on October 20, 1994, regarding a recorder device for pre- existent information, comprising a photosensitive material to be adhered to a specific region on the surface of a monitor, typically a television monitor. A symbol transmitted by the TV station at that region of the monitor, e. g. the station logo, sensitizes the photosensitive material after a given time of exposure. The photosensitive material then becomes a carrier of the transmitted logotype, i. e. the broadcast information is stored exactly as it is and can be later checked by means of a photo development process. The second reference is the U. S. Patent 5,790, 169 from the same inventor of the German Patent as mentioned above. It refers an enhancement of the previous one, which operation does not allow the image retained by the photosensitive material of the recording device to be sufficiently neat. To solve this problem, (a) the recording device includes a layer ("diaphragm layer") whose purpose is to generate a focus effect by restricting the passage of light and increasing the distance between the monitor surface and the photosensitive material; and (b) it intersperses regions containing a photosensitive material with regions without photosensitive material, thus creating a kind of a chessboard with predetermined fields, which may or not be sensitive to the issued light, helping in the storage of the broadcast information in a codified way.

In both cases, the way the monitor light impresses the photosensitive material has low efficacy. In the first reference, there is lack of focus, solved in a complex and not much efficient way, by using a focusing lens layer while, in the second reference, a thicker device is used. It must also be pointed out that the photosensitive material typically requires a later photographic development step which increases the costs and the complexity of its use.

DESCRIPTION OF THE INVENTION The invention intends to simplify and optimize the devices as found in the state of the art, since the need of focus over an image on the monitor screen is eliminated. It is a photosensitive device characterized by comprising an information layer substantially adjacent to a photosensitive layer, such that when said device is exposed to a light source, total or partial transfer of the information occurs from the information layer to the photosensitive layer.

The information layer comprises a substantially transparent substrate, typically a thin plastic sheet (polyester, polypropylene, PVC, etc.) with regions of different non-opaque colors - for example colors provided by flexographic paint), with the combination of said colors expressing the information to be transferred to the photosensitive layer by means of filtering the light to which it is exposed. Merely illustrative examples of an appropriate substrate useful as an information layer are transparencies for laser or inkjet printers, such as those sold by the U. S. companies Verbatim Corporation, Hewlett-Packard Company or Seiko Epson Corporation. As used herein, "substantially transparent" means a substrate allowing the passage of light radiation, even if partially.

The photosensitive layer comprises any photosensitive substrate, e. g. a photographic emulsion, a photochromic paint or substrate containing one or more elements that change properties when exposed to light. In a particularly appropriate way, one uses a photographic paper based on an emulsion of silver salts, because it can be exposed to red light without being substantially sensitized and gradually acquires gray tones when exposed to white light, not requiring any chemical treatment such as photo development. Non-limiting examples of black and white photo paper useful to the invention are the papers Kodabromide II RC, Kodabrome F3 and Kodak Linagraph, all from the U. S. company Eastman Kodak Company, Multigrade IV RC from the English company ILFORD Imaging UK Ltd., etc.

The device of the invention is particularly different from those known in the prior art in the following aspects: - the information is already previously contained in the device within its information layer, and the exposure measurement is evaluated by transferring the information to the photosensitive layer, while in the previous art the information is external to the device, which only captures it;

- it is not necessary to create a focus on the external stimulus source, making unnecessary the use of specific means for that purpose;

- information coding is more versatile, since it is obtained from light filtering (therefore depending on the light filters on the information layer and the wavelength of the external stimulus), while in the previous art it is effected by blocking the light (depending on the coding elements of the external stimulus and the geometry of cuttings on the diaphragm layer);

- it is much less thick (typically between 0.5 and 1.5 mm), since it is not dependent on physical means to reach the focus of the broadcast information, in comparison to about 5 mm of the devices of the previous art;

- being less thick, it can be manufactured by high speed rotating processes, while in the previous art the thickness devices require flat printing or stamping processes, which are slower and less productive;

- it does not require precise positioning over the monitor, making unnecessary the use of special marks on the external outline of the device to guarantee the correspondence between the active regions and the coding elements of the light stimulus as required by the previous art;

- the control against result forgery comprises the inhibition of the total or partial information transfer process from one layer to the other, while specific stimulation is required in the previous art, by means of coded information elements from at least one of the specific regions.

Within a typical embodiment, the device of the invention also comprises other material layers or means aiming to avoid light exposure of photosensitive material before and after the use and which can also serve as package for its storage after use. The device of the invention can also be equipped with fixing means, allowing its temporary maintenance on the surface of the monitor to which it will be exposed during use, e. g. dots or lines of non- permanent adhesive.

The operation of the device of the invention uses optical principles, particularly by selective light filtering of specific wavelengths, combined with photo-sensitive materials. The information is coded by using light filters with different selectivities arranged in such a way as to represent the desired information. A filtering layer is therefore used, comprised of specific geometry regions corresponding to filters with different selectivities. When said filtering layer is interposed between a light source and a layer comprised of photosensitive material, the regions of said latter layer corresponding to the filtering regions with different selectivities, can be differently sensitized, thus creating on the photosensitive layer a coded or non-coded information corresponding to the filter layer.

Since the photosensitive layer is more sensible to given wavelengths and insensible to others - i. e. it presents variable sensitivity dependent on the light wavelength, information can be coded with filters, so that, within specific stimulation conditions, information transfer does not occur. In this a case, it is particularly appropriate that the stimulation covers a substantial part of the device to be efficient as inhibitor to the information transfer process, thus allowing prompt evaluation of the conditions of the sensitized photosensitive area. The stimulation conditions do not require, however, any special geometry and can be of any shape.

Verification of the occurrence or not of the transfer process can be performed by visual inspection, not requiring the chemical development of the photosensitive material. This means that the photo emulsion as applied over the paper base itself will present regions of different gray tones, depending on both the quality of the light stimulus (intensity, color or duration) and the light filtering by the information layer.

Furthermore, the speed of the transfer process can be regulated, as one skilled in the art knows, and can be designed to occur within a relatively long time period and be verified by a reading device, thus determining the stage in which the transfer process is at in a given moment. Therefore one can have an exposure time estimate, proportional to the stimulus condition to which the device of the invention was submitted and to the sensitivity of the photosensitive material. The device of the invention may be of any shape, the square and round shapes being particularly appropriate.

The information layer comprises any material which does not substantially block the passage of light, is preferably transparent and provided with different colors to filter light of different wavelengths. In a particularly appropriate way, the information layer of the device of the invention makes use of a combination of the colors red, blue and yellow.

The photosensitive material of the photosensitive layer of the device of the invention is of any kind known in the art, particularly those based on emulsions with silver salts.

Within a particular embodiment of the invention, there is no physical layer interposed between the information layer and the photosensitive layer, although both can be comprised of one or more distinct elements. For example the information layer can be comprised of two or more sheets of different colors which are juxtaposed, superposed or combined in any other way.

The use of the device of the invention for the purposes of checking audience fidelity presupposes light emission within a specific region of the television monitor and the placement of the device of the invention on that same region. As mentioned, the broadcaster does not need to transmit information such as letters, numbers or symbols, just luminous signals comprising one or more colors, so that the information contained in the device is coded as desired, thus expressing for later verification, by means of the configuration as transmitted from the information layer to the photosensitive layer, if the spectator kept its TV set tuned to that station for the duration of some specific program.

Another aspect of the invention is an information coding process characterized by comprising the following steps: - generating or localizing a light stimulus;

- having light from the light stimulus pass through an information layer comprising colored filters whose arrangement expresses information;

- capturing the filtered light wave front upon a photosensitive layer substantially adjacent to said information layer.

The result of the information coding process is an image whose features (shape, intensity, etc.) are useful when associated to the realization an event and its duration, e. g. proof of the broadcasting of a specific television program on a specific channel, for a given time interval. EXAMPLES OF EMBODIMENTS

The example below, with the help of the attached figures, illustrates a particular embodiment of the invention and is merely an example, not imposing any limitation to it, be it relative to dimensions, materials, proportions, quantity of components or any other aspect other than the ones included in the claims appended at the end of this description.

Figures 1 , 2 and 3 illustrate an alternative of embodiment of the invention, in which the information contained in the device of the invention is a five-edge star figure. The distance shown between layers 1 and 2 does not exist in practice, but it is shown herein just to illustrate the operation of the invention. In Fig. 1 one sees the transparent information layer (1)

(transparency HP C2934A from the company Hewlett-Packard) provided with a star (A), whose internal side is yellow and whose external side (B) is red (image obtained by printing over the transparency with an Epson Stylus Color 600 printer by using paint from specific paint cartridges for that printer). Said layer (1) overlaps a photosensitive layer (2), a black and white photographic paper based on silver salts (Kodabromide II RC from the company Kodak) and, before use, both layers are protected from light by additional wrapping layers (not shown). Fig. 2 shows that when the device of the invention is exposed to a red light source (C), the surface (3) of the photosensitive layer (2) is not sensitized because only non-sensitizing red radiation reaches the photosensitive layer. In Fig. 3, when white light (D) is used as a source of light stimulus, the surface (3) of the photosensitive layer (2) is sensitized with the image (4), reproducing the shape of the star (A) (which is the information contained in (1)), since the yellow filter does not keep other wavelengths from passing, which are able to sensitize the photosensitive layer (the yellow filter does not hinder the total or partial passage of green or blue radiation, which are able to sensitize the photographic paper based on silver salt emulsion).

In Figure 4A, a specific device (5) is illustrated according to the invention. Said device (5) is square with approximate dimensions of 35 mm x 35 mm x 1.5 mm, has sides A and B, side A facing the light source and side B opposed to side A, in which:

- (10) is a front external protection layer, blocking the light on side (A) of the device; layer (10) is taken off when the device is put into use;

- (20) is a peripheral distribution of pressure sensitive adhesive (PSA) between layers (10) and (30), shown in detail on Fig. 4B, used to temporarily fix the device (5) to the television monitor;

- (30) is an information layer (corresponding to (1) on Figures 1 , 2 or 3);

- (40) is a photosensitive layer (corresponding to (2) on Figures 1 , 2 or 3); - (50) is an extern protection upstream layer blocking the light on side (B); and

- (60) is a through hole allowing the alignment of the device with a lighting dot sent by the broadcaster for appropriate localization of the device at the monitor.

It will be appreciated that the description of the invention presented herewith, as well as the examples, allow a person skilled in the art to realize the invention including changes within the typical knowledge of that technology area, without deviating from the scope of the invention as indicated by the attached claims.

Claims

1 . A photosensitive device for internal information transfer, which comprises an information layer substantially adjacent to a photosensitive layer, so that, when said device is exposed to a light source, total or partial information transfer occurs from the information layer to the photosensitive layer.

2. Device of claim 1 , in which said information layer comprises a substantially transparent laminar substrate with one or more non-opaque color regions.

3. Device of claim 2, in which the used colors are yellow, blue and red.

4. Device of claim 1 , in which said photosensitive layer is a substrate comprising a photographic emulsion based on silver salts.

5. Device of claim 1 , the thickness of which is between about 0.5 and about 1 .5 mm.

6. Device of claim 1 , which further comprises means to avoid the exposure of the photosensitive layer to light before and after use.

7. Device of claim 1 , which further comprises temporary fixing means to a monitor screen during use.

8. Photosensitive device (5) for internal information transfer which successively comprises:

- an anterior external protection layer (10), detachable;

- a distribution of lines or dots of adhesive (20) for temporary adhesion of the device to a specific region of an image monitor; - an information layer (30);

- a photosensitive layer (40);

- an external protection posterior layer (50);

- a through hole (60) to align the device with a light dot on the monitor.

Information coding process which comprises the following steps:

- generating or locating of a light stimulus;

- having light from the light stimulus pass through an information layer that comprises colored filters whose arrangement expresses information;

- capturing the filtered light wave front upon a photosensitive layer substantially adjacent to said information layer.