WO1992001565A1

WO1992001565A1 - Erasable optical recording medium for coloured visual information

Info

Publication number: WO1992001565A1
Application number: PCT/DE1991/000580
Authority: WO
Inventors: Klaus M. Moses
Original assignee: Telenorma Gmbh
Priority date: 1990-07-19
Filing date: 1991-07-12
Publication date: 1992-02-06
Also published as: DE4022974A1

Abstract

The recording medium disclosed comprises a substrate carrying a heat-sensitive film which can be converted into different optical states under the influence of temperature (e.g. opaque and transparent). These states are permanent at normal ambient temperature (e.g. room temperature) and reversible by heating to specific temperatures. The recording medium is designed such that four dots (F) are combined in groups of four to form zones (B), each of the dots (F) having a different primary colour (e.g. red, yellow, blue or black). If the heat-sensitive film over a dot (F) in a zone (B) is converted by appropriate warming to the transparent state, the dot lying under the film becomes visible. This makes it possible to record coloured data, either on a recording medium in the form of a sheet or in the form of a continuous strip from a display device.

Description

Erasable optical recording medium for colored information

The invention relates to an erasable optical recording medium consisting of a carrier and a heat-sensitive layer attached thereon with optical states which can be influenced by different temperatures (for example opaque and transparent), the states in the normal ambient temperature (for example room temperature) permanently and by heating are reversible to certain temperatures.

Such a record carrier is already known. In European patent specifications EP-PS 0 000 868 and 0 014 826, for example, a body with reversible fixed and temperature-changeable is - 2 -

Light extinctions are described, which is designed as an erasable record carrier consisting of a pair of substances which, for example, when heated from the state of maximum light extinction to a clear temperature below a conversion temperature and subsequent cooling and below a lower temperature value, a decreasing light extinction with increasing heating temperature having.

The recording and erasing process can be repeated as desired, it being possible for the recording to be carried out by means of finely concentrated heat or light radiation or else by means of contact heat. The known recording medium is thus suitable for the erasable recording of numbers, letters, images, patterns, etc., and the recordings can be made both transparently in an opaque environment and opaque in a transparent environment.

The object of the invention is to develop the known recording medium in such a way that it is also suitable for recording colored information.

This object is achieved in that an atrix-shaped grid of colored, punctiform or correspondingly shaped surfaces is attached to the support on the side facing the layer.

The colored recording is done by heating the overlying heat-sensitive layer in the area of the respective area with the desired color in such a way that it assumes the transparent state, while the remaining area of the layer remains in the opaque state in which it was before the start of the Recording process has been brought uniformly. A further development of the invention consists in that three point-shaped surfaces are combined to form an area, each of the point-shaped surfaces having a different basic color

05 (for example red-yellow-blue).

A further development of the invention also consists in the fact that four point-shaped surfaces are combined to form an area, each of the point-shaped ones

10 surfaces have a different basic color (for example red-yellow-blue-black).

This measure makes it possible to reproduce colored information in all colors. The size of one

¹⁵ punctiform surface depends on the intended use. When reproducing colored images on sheet-like information carriers in the common paper formats, the size of such an area is smaller than, for example, the impact area of one

- - Needle of a dot matrix printer. This could correspond to an area, for example. If the recording medium according to the invention is used with large display areas, the individual areas can assume orders of magnitude of one or more mm ² .

25

If only three primary colors or four primary colors without the color black are used in the individual areas, then the object stated at the outset is achieved in that the support is colored black on the side facing the layer, and on the side of the layer facing away from the support a matrix-shaped grid of colored, punctiform or correspondingly shaped surfaces is attached, and that a second heat-sensitive layer is applied on the first layer, the temperatures for changing the optical properties of the two layers being different. In this embodiment of the recording medium, the first layer lying under the punctiform surfaces is only converted from the opaque to the transparent state if black is required as the fourth or fifth color.

Further advantageous embodiments according to the invention result from the subclaims.

The invention is explained in more detail by means of exemplary embodiments which are shown in the drawing.

It shows:

1 shows the graphical representation of the two states of the layer as a function of different temperatures,

2 shows the structure of the recording medium with a temperature-sensitive layer,

3 shows the structure of the recording medium with two temperature-sensitive layers,

4 shows the structure of an area with three punctiform surfaces,

5 shows the structure of an area with four punctiform surfaces

and

6 shows the graphical representation of the two states of the two layers of the recording medium according to FIG. 3 as a function of different temperatures. 1 shows the state transitions as a function of temperature for a possible thermosensitive layer. From the diagram it is clear that starting remains until the temperature TO and the transparent state to ^• for Temepratur T2 obtained from a first temperature (ambient temperature) of the non-transparent state (opaque) of the material, TO at about 35 degrees C and T2 in is about +73 degrees C. Starting from

The material can be in opaque condition and ambient temperature. . . in the area between TO and Tl are continuously switched to a state of maximum transparency. Starting from the transparent state and ambient temperature, the changeover to the opaque state occurs suddenly at temperature T2. The temperature Tl is around 64 degrees C. This characteristic also enables the generation of any levels between opaque and transparent by appropriate metering of the writing energy.

For writing transparent symbols in opaque

In the environment, the record carrier must first be converted to the opaque state. This is done by an erasing process in which the thermosensitive layer is first heated to at least the temperature T2 and then cooled to TO or less than TO.

If the layer is then heated to a temperature between T1 and T2, which is, for example, between +64 and +73 degrees C, the layer becomes transparent and maintains this state even after cooling to the ambient temperature.

2 consists of a carrier material T, the areas B applied thereon and the heat-sensitive layer S. The carrier material T can either be made of paper or an opaque plastic or also of a transparent one Material. In the first case such constructed record carrier may for reproducing far¬ biger information, for example, in common Pa¬ pierformaten or also serve as a display device which is illuminated by the daylight, while the recording medium is composed ^• suitable from a transparent carrier material especially for display devices, which can be illuminated . The light source sits on the side of the carrier T facing away from the layer S.

The areas B are applied to the side X of the carrier T facing the layer S, for example by a printing or also a screen printing process.

4, it is assumed that this consists of three point-shaped or appropriately shaped surfaces F with the colors blue (b), red (r) and yellow (g). The surfaces F are arranged in an atrix shape, namely in columns S1 to Sn and rows Z.

5 shows the structure of an area B consisting of four point-shaped surfaces F, which are the primary colors red (r), yellow (g), blue (b) and black

(s) correspond. It is also possible that green is used instead of black. In this arrangement too, the surfaces F are arranged in a matrix, namely in columns S1 to Sn and in rows Z.

The recording process for information now consists in the layer S (see FIG. 2 or 3) being transferred from the opaque to the transparent state in the region which is above a punctiform surface F by appropriate heating. The punctiform colored surface F located under the layer s is thus visible. Depending on desired color can now be made visible within a region B either only one colored area F or several colored areas F in the manner described. The arrangement of four colored areas F within a region B has the advantage that the control of the means heating the layer S (see FIG. 2 or 3) at the relevant points is easier than with an arrangement of the areas F according to FIG Fig. 4.

For the display of information on the recording medium according to the invention, area B forms the smallest image unit from which the image is composed. This means that, for example in the case of a dot matrix printer, the area B corresponds to the area which can be marked by the individual needle. Depending on the desired resolution, this can mean that the areas F must have very small dimensions.

In the case of a large-area display device, the requirements for the resolving power may not be so great, so that the punctiform areas F can also assume larger dimensions, for example in the order of magnitude of a few mm ² .

The action of heat to change the optical properties of layer S according to FIG. 2 or 3 can now take place either by bundled heat radiation or also by contact heat. With a very high resolution, i. H. very small punctiform surfaces F, only bundled thermal radiation, for example a laser beam, is possible, while heating with resistors is also conceivable for larger punctiform surfaces F.

In the explanation of the arrangement of the punctiform surfaces F according to FIG. 5, it was mentioned that on the

O 92/01565 PCT / DE91 / 00580

- 8th -

Basic color black can be omitted. For additional reproduction of this color in accordance with the arrangements in FIGS. 4 and 5, the recording medium in accordance with FIG. 3 can be constructed accordingly. A first heat-sensitive layer S1 is attached to an opaque carrier T on the side X facing the layer S, a black layer in the region X being provided between the carrier T and the first heat-sensitive layer S1.

¹⁰ On the side of the first layer S1 facing away from the carrier T, the areas B are applied, which are covered by a second heat-sensitive layer S2. The basic colors of a region B are reproduced in that the desired ones

I ⁵ places of the areas F not shown (see FIG. 4 or 5) of the area B, the second layer S2 is brought into the transparent state in order to make the color in question visible. Instead of one of the basic colors, the

If the color black is desired, the first layer S1 at the relevant points is also heated by heating from the opaque to the transparent state, as a result of which the black color on the carrier T becomes visible 5. With this construction, it can be expedient not to apply the colors of the area B in a covering but in a translucent manner, as is also the case when the support T is transparent.

In the process of recording information, it is of particular importance that the layer S above the desired area F is converted into the transparent state within a region B, ie that the coloring information of region B is reproduced exactly 5. This presupposes that the heating means, for example a bundled light beam or the resistance element, is positioned exactly within a region B, since at one Displacement there is a risk that the heating in the wrong place will either make no colored surface visible at all or a colored surface with an undesired color. For precise positioning, the recording medium T is therefore provided, for example, on its side facing away from the layer S with corresponding markings which correspond, for example, to the rows Z and columns S. The exact positioning of the action of heat on the layer S can be controlled by means of corresponding optical scanning devices which act on the back of the recording medium T, ie on the side of the medium T facing away from the layer S.

These markings can also be applied on the side of the layer S or S2 facing away from the carrier T, specifically such that they are not visible, for example, when illuminated with normal light, for example colors fluorescent under UV light.

This applies particularly to those recording media in which the carrier T (see FIG. 2 or 3) is transparent.

If the columns S (see FIG. 4 or 5) are in the direction of movement of the recording medium or the writing device, they can be marked, for example, as solid lines. The column of each punctiform surface F does not necessarily have to be marked, but for example every fifth. The line markings can either be attached to the edge of the recording medium, although it is also not absolutely necessary to mark each line of the punctiform surfaces F.

The column marking is detected by a suitable sensor device and the recording medium transversely to the direction of movement by suitable means positioned such that the writing device, not shown, is located in an area B.

An exemplary temperature behavior of the two heat-sensitive layers of the recording medium according to FIG. 3 is shown in FIG. 6. If both layers S1 and S2 are in the opaque state at room temperature TO, layer S2 begins to become more translucent in the area of temperature T3 due to the increasing heating of the recording medium, while layer S1 initially still fully retains the opaque state. As soon as the temperature T1 is reached, the layer S2 changes to the transparent state, while the layer S1 still remains almost in the opaque state. If the temperature is not increased above T1, but the recording medium is cooled again to the room temperature TO, the transparent state of the layer S2 and the opaque state of the layer S1 are retained, as a result of which only the colored areas B which are visible through the layer S1 in the opaque state is highlighted in white.

If, on the other hand, the recording medium is further heated to the temperature T2, the layer S1 lying below the layer S2 also changes to the transparent state. If the temperature is not raised further above T2, but the recording medium is cooled again to the room temperature TO, the transparent state is maintained in both layers S1 and S2. The white background of the colored areas is no longer available, i. H. the colors, which are transparent in themselves, appear against a black background and are therefore perceived by the eye as black.

To delete the information applied, ie converting the layer S1 or the layer S2 into the opaque state, the recording medium must be heated to at least the temperature T4, which is above the temperature T2. After subsequent cooling to room temperature TO, both layers S1 and S2 maintain the opaque state.

Since deleting the recorded information, e.g. H. the transition of both layers into the opaque state need not take place independently of one another, the temperature at which both layers S1 and S2 are converted into the opaque state can be the same for both layers. The temperature behavior of the layers S1 and S2 shown in FIG. 6 is only exemplary and can also be selected in a different form, it is only necessary to ensure that the transition temperature from the opaque to the transparent state for the layer S2 must be lower than that of the Layer S1 and the transition temperature from the transparent state to the opaque state of layer S2 must be above the transition temperature from the opaque to the transparent state of layer S1. In any case, it must be ensured that the layer S1 can be converted from the opaque to the transparent state without changing the transparent state of the layer S2 into the opaque state. It is assumed that the recording of information takes place in that the layers S 1 or S 2 which are in the opaque state are located at those points which are above the punctiform surfaces F (see FIG. 4 or 5) As part of the recording process in the transparent state.

A suitable device for recording information on the heat-sensitive layer described at the outset is described in PCT / DE90 / 00482. On a recording device in which a - 12 -

Recording medium with a heat-sensitive layer is used, is extensively discussed in PCT / DE90 / 00484, i. H. also that the recording medium according to the invention can be provided with information with the aid of the recording device described there and can be used in accordance with the display device explained there.

Claims

PATENTAN'S SMOKE:

1. Erasable optical recording medium consisting of a carrier and a heat-sensitive layer mounted thereon with optical states which can be influenced by different temperatures (for example opaque and transparent), the states being in the normal ambient temperature (for example

Room temperature) are permanent and reversible by heating to certain temperatures, characterized in that on the support (T) on the side facing the layer (S) a matrix-shaped grid of point-shaped or appropriately shaped surfaces (F) is attached.

2. An erasable optical recording medium ^D consisting of a support having thereon a heat-sensitive layer can be influenced by different temperatures optical states (for example, opaque and transparent), wherein the states in the normal ⁰ ambient temperature (e.g.

Room temperature) are permanent and reversible by heating to certain temperatures, characterized in that the support (T) is colored black on the side facing the layer (Sl), that on the side of the layer (Sl) facing away from the support (T) Matrix-shaped grid of transparent colored punctiform or correspondingly shaped surfaces (F) is attached and that on the first layer (S1) a second heat-sensitive layer

(S2) is attached, the temperatures for changing the optical properties of the two layers being different.

3. Erasable optical record carrier according to claim 1 or 2, characterized in that in each case three punctiform surfaces (F) are combined to form an area (B), each of the punctiform surfaces (F) being different

Basic color (for example red, yellow, blue).

4. Erasable optical recording medium according to claim 1 or 2, characterized in that four point-shaped surfaces (F) to one

Area (B) are summarized, each of the punctiform surfaces (F) have a different basic color (for example red-yellow-blue-black).

5. Erasable record carrier according to claim 4, characterized in that the four punctiform surfaces (F) are designed such that in one line alternately two surfaces (F) each with a different basic color and in the adjacent line alternately two surfaces each with a different Basic colors are arranged, the basic colors of the areas (F) of two adjacent lines of an area (B) also being different.

6. Erasable optical recording medium according to one of claims 1, 3 to 5, characterized in that the carrier (T) itself is colored white or is colored white on the side (X) facing the layer (S).

7. Erasable optical recording medium according to one of claims 1, 3 to 5, characterized in that the carrier (T) is transparent or translucent.

8. Erasable optical record carrier after

Claim 2, characterized in that the temperature for changing the optical

Properties of the first layer is greater than the temperature for changing the optical

Properties of the second layer (S2).

9. Erasable optical recording medium according to one of claims 1 to 8, characterized in that on the side facing away from the carrier (T) of the layer (S, Sl) markings are attached, which the grid and the position of the colored punctiform surfaces (F) and / or correspond to the areas (B).

10. Erasable optical recording medium after

Claim 3, characterized in that two punctiform surfaces (F) each

Area (B) in a row next to each other and the third punctiform surface of this area in the adjacent row, namely in one of the two

Split the other two punctiform surfaces

(F) are arranged.