JPH01133792A - Apparatus for forming image for projection - Google Patents

Abstract

PURPOSE:To form an image for projection through a change in light transmittance at an energized part, by electrically energizing according to an image signal a predetermined part of a recording material in which a thermal recording layer having a light transmittance reversibly varied depending on temperature, a transparent conductor layer and an electric heat generating layer are sequentially provided on a transparent support. CONSTITUTION:A recording material A comprises a transparent support 1, a reversible thermal recording layer 2, a transparent conductor layer 3 and an electric heat generating layer 4, with a protective layer 5 optionally provided on the layer 4. By controlling the quantity of an electric current passed to the heat generating layer, the light transmittance of the thermal recording layer can be arbitrarily selected. Namely, specified signal electrodes are selected according to an electric signal transferred from a controlling system, and the surface of the recording material A is electrically energized according to the electric signal, whereby an electric current flows from the electric signal electrode 6 through the heat generating layer toward a return circuit electrode 7. In this case, the area of the signal electrode is much smaller than that of the return circuit electrodes, so that the current density directly below the signal electrode is extremely high as compared with that directly below the return circuit electrode, and the part of the heat generating part corresponding to the signal electrode is caused to selectively generate heat.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a projection image according to an electrical signal.

2. Description of the Related Art In recent years, overhead projectors have been widely adopted as a means of transmitting information in various fields. As is well known, an overhead projector is an optical device that enlarges and projects an image formed on an original projection film. Conventionally, the original projection film used to form this projection image is (a) a transparent plastic film. (b) Heat-shrinkable plastic film coated with a penetrating agent, (c) Made from non-shrinkable or low-shrinkable polypropylene film or polystyrene film, (d) Heat-shrinkable plastic film. There are known methods in which a layer of a thermochromic substance or a thermofoamable substance is inserted between two plastic films having different shrinkage temperatures, and (e) a plastic film containing or coated with a thermochromic substance. When obtaining projection images from these original projection films, (a)
In the case of original film, a colored image is created by hand using a special drawing material, and in the case of other original film, the original is superimposed on this, and infrared rays are irradiated from the film side to reveal the part of the film that corresponds to the original image. It is thermally softened, thermally shrunk, or thermally colored, thereby forming a fine uneven pattern or a colored image.

However, all of the conventional original projection films have disadvantages in that they have poor thermal sensitivity, contrast and resolution of projected images, are difficult to increase in area, and cannot be used repeatedly, resulting in high costs for projection images.

An object of the present invention is to provide a projection image forming apparatus that can repeatedly form a high-contrast and high-resolution projection image with high sensitivity and a large area easily.

The projection image forming apparatus of the present invention is as shown in FIG.
A recording medium A, in which a heat-sensitive layer 2 whose light transmittance changes reversibly depending on temperature, a transparent conductive layer 3, an energized heat-generating layer 4, and a protective layer 5 if necessary are sequentially provided on a transparent support 1; A recording electrode B (consisting of a signal electrode 6 and a return electrode 7) that contacts the surface of the recording medium and energizes a predetermined part of the recording medium A according to an electric signal, and a power source C that supplies current to this recording electrode. It is characterized by the following structure.

The principle of forming a projection image using the apparatus of the present invention is as follows.

That is, when the recording electrode B is brought into contact with the surface of the recording medium having the above-mentioned layered structure and electricity is applied to a predetermined point of the recording medium according to an electric signal (image signal), the current-carrying portion (directly under the input signal electrode) The heat generating layer generates heat due to Joule heat, and this heat changes the light transmittance, that is, the transparency of that portion, and a projection image is formed.

Next, each member used in the device of the present invention will be explained.

First, as described above, the recording medium is basically composed of a transparent support, a reversible heat-sensitive layer, a transparent conductive layer, and an energized heat-generating layer, and a protective layer is further provided on the heat-generating layer if necessary.

In such a recording medium, the heat-sensitive layer has a property that its transparency changes reversibly depending on the temperature. Therefore, the heat-sensitive layer is mainly composed of a resin base material and an organic low-molecular substance dispersed in the resin base material. The image forming principle of the apparatus of the present invention utilizes the above-mentioned change in transparency due to temperature in the heat-sensitive layer of the recording medium, and this will be explained with reference to the drawings. In FIG. 2, the heat sensitive layer is T. At room temperature below, it is cloudy and opaque, but when heated to a temperature between 10 and 12, it becomes transparent, and in this state it is T. It remains transparent even after returning to room temperature below. Further heating to a temperature of 13 or higher results in a translucent state intermediate between maximum transparency and maximum opacity. Next, when this temperature is lowered, the liquid returns to its initial cloudy and opaque state without becoming transparent again. Note that when this opaque state is heated to a temperature between To and T1 and then cooled to room temperature, that is, a temperature below T, it can assume a state between transparent and opaque. Also, the above
Even if it becomes transparent at room temperature, if it is heated again to a temperature of 13 or above and returned to room temperature, it will return to its cloudy, opaque state. That is, it can take both opaque and transparent forms, as well as intermediate states, at room temperature.

Therefore, if the heat sensitive layer of the heat generating layer is heated with Joule heat generated by energizing, the portion heated to a temperature of -4= between T□ and T2 becomes transparent and can transmit light. T again. The portion where heating is stopped at a temperature between −T1 becomes translucent. That is, the light transmittance of the heat-sensitive layer can be arbitrarily selected by controlling the amount of current applied to the heat-generating layer (current value per unit time or duration of current application).

As the resin base material used for the above-mentioned heat-sensitive layer, a resin that has excellent transparency, is mechanically stable, and has good film-forming properties is suitable. Such resins include polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride acrylate copolymer Vinylidene chloride copolymers such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer; polyester; polyamide; polyacrylate or polymethacrylate or acrylate Examples include tol methacrylate copolymer and silicone resin. These may be used alone or in combination of two or more.

On the other hand, the organic low-molecular substance may be appropriately selected depending on the temperature T1 to T3 in FIG.
00°C, particularly preferably about 50 to 150°C. Such organic low-molecular substances include alkanols; alkanediols; halogen alkanols or halogen alkanediols; alkylamines; alkanes; alkenes;
Alkynes; halogen alkanes; halogen alkenes, halogen alkynes; cycloalkanes; cycloalkenes; cycloalkynes; saturated or unsaturated mono- or dicarboxylic acids or their esters, amides, or ammonium salts; saturated or unsaturated halogen fatty acids or their esters; Amides or ammonium salts; Allyl carboxylic acids or their esters, amides, or ammonium salts; Halogen allyl carboxylic acids or their esters, amides, or ammonium salts; Thioalcohols; Thiocarboxylic acids or their esters, amines, or ammonium salts ; Examples include carboxylic acid esters of thioalcohols. These may be used alone or in a mixture of two or more. The carbon number of these compounds is 10-6
0, preferably 10-38, especially 10-30. The alcohol group moiety in the ester may be saturated or unsaturated, and may be substituted with halogen. In any case, organic low-molecular substances have oxygen in their molecules,
At least one of nitrogen, sulfur and halogen, such as 1OH
5-COOHl-CONHl-COOR1-NH-1-
A compound containing NR2, -5-1-3-3-1-〇-, halogen, etc. is preferable.

More specifically, these compounds include higher fatty acids such as lauric acid, dodecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, stearic acid, behenic acid, nonadecanoic acid, arachidic acid, and oleic acid; methyl stearate, and tetradecyl stearate. , esters of higher fatty acids such as octadecyl stearate, octadecyl laurate, tetradecyl palmitate, tocosyl behenate; C1GH33
”C1GR33C□G R33-s-cIG R3:I
C111H3□-0-C□81 (3□ C1
□H2, -8-C1□1 (zsCl, R39-3-C□
9H3゜ C engineering, R2, -3-8-C1□1
(There are ethers or thioethers such as 2s and +13.

-8= The weight ratio of the organic low molecular weight substance to the resin base material in the heat-sensitive layer is preferably about 1:0.5 to 1:16.

The heat-sensitive layer as described above is formed by a normal solution coating method.

Next, the transparent conductive layer is ITO (tin oxide/indium), Sn
It consists of a thin layer of transparent conductive material such as O□, In2O3, etc., and functions as an electrode when electricity is applied. This layer is formed on the heat-sensitive layer by vacuum deposition, coating from a solution, or the like. The surface resistance of the conductive layer is 1×104Ω/mouth or less, preferably I
Xl, 02Ω/mouth or less.

Next, the current heating layer is a layer that heats the heat sensitive layer by the heat generated by current, as mentioned above, and is made of a resin binder that can withstand the heat when electricity is applied, such as a resin binder used for the conductive layer in the resin base material used for the heat sensitive layer. It is made by dispersing an appropriate amount of fine powder of a transparent conductive agent. Since the heating layer generates heat by passing a current through it, the volume resistance is more important than the surface resistance, and I
"2~1x104Ω mark, preferably lx10"1~lx
It is set to about the IO2Ω mark. Note that this layer is formed on the conductive layer by a normal solution coating method.

Furthermore, the protective layer is a layer that protects the heat generating layer from rubbing by the recording electrode, and is made of a wear-resistant resin.

Specifically, urethane crosslinked styrene-methyl methacrylate-1 copolymer, ester crosslinked styrene-methyl methacrylate copolymer, polysiloxane copolymer, and the like are suitable.

As the transparent support for supporting each of the above layers, a plastic film such as a polyester film, a glass plate, etc. are used.

Furthermore, as shown in FIG. 3, the recording medium of the present invention has three primary colors (R...red, G...green, B...
- A color filter layer 8 having a mosaic pattern of blue) can be provided. If such a recording medium is used, it is also possible to obtain a multicolor projection image. In this case, by making the background part of the projection image cloudy and making the image part transparent, it is possible to obtain a projected image of a colored image on a black background.

As described above, the recording electrode that contacts the surface of the recording medium is composed of a signal electrode and a return electrode, and the signal electrode has a large number of needle-like electrodes arranged at a predetermined density, for example, 8 electrodes/mm, in a line or in a staggered pattern. On the other hand, the return electrode is arranged as a single electrode in parallel to the signal electrode array. Note that the cross-sectional area of the return electrode is much larger than each signal electrode. The entire recording electrode has a cross-sectional shape as shown in FIG. 4, and the periphery of each electrode is molded with resin 9. The return electrode is grounded, and the signal electrodes are each connected to a current supply power source via a transistor. A specific signal electrode is selected by the electric signal transferred from the control system, and the transistor becomes conductive. As a result, a current is supplied from the power source to the selected signal electrode, and the heat generating layer directly under the signal electrode generates heat by being energized. The reason why only the portion directly below the signal electrode generates heat is as follows. In other words, when electricity is applied to the surface of the recording medium in response to an electric signal, the current passes through the heat generating layer from the signal electrode to the return electrode based on the electric signal, but the signal electrode is overwhelmingly stronger than the return electrode. Since the area is small, the current density directly under the signal electrode is much larger than that directly under the return electrode, and the heat generating layer in the portion corresponding to the signal electrode selectively generates heat.

Next, a projection image forming/projection process in which the apparatus of the present invention is combined with an image erasing mechanism and an overhead projector will be described. FIG. 5 shows an example of such a combination device, in which an endless belt-like recording medium A is connected to a plurality of rollers 1.0a.
, 10b, 10c, and 10d, and a projection light source 11. Reflector 1
2. A Fresnel lens 13 for parallelizing the light rays from the light source and a transparent support plate 14 for correcting the deflection of the recording medium A and supporting it in a flat state are provided. The recording body drive roller and a backup roller 15 having appropriate elasticity are further arranged on the inner peripheral side of the recording body. The backup roller 15 supports the recording electrode B, which is pressed against the recording medium A with a predetermined pressure, from the back surface of the recording medium A.

A power supply C is connected to the recording electrode B, and a control system (not shown) is connected to the recording electrode B.
Current can be supplied to the recording electrode B according to the image signal transferred from the recording electrode B.

A thermal roller 16 for image erasing is provided at other positions on the outer peripheral surface of the recording body.
is provided to supply heat to the entire surface of the recording medium to erase the projection images that have already been recorded and are no longer needed. In addition, an imaging lens 17 and a reflection mirror 18 for projecting the projection image irradiated by the light source 11 onto a screen (not shown) or the like are arranged at predetermined positions as members for the overhead projector. .

In the apparatus shown in FIG. 5, the recording medium A is first heated to a temperature between T1 and T2 in FIG. 2 by the image erasing heat roller 16, and then returned to room temperature to make the entire recording medium transparent. Next, when the recording body A is energized by the recording electrode B in accordance with the electric signal, the heating layer of the recording body generates heat in accordance with the current value. As a result, the heat-sensitive layer portion where the temperature reached 13 or higher became almost completely cloudy.
The part where the temperature has stopped increasing during the To-T process or between T2 and T3 becomes translucent depending on the temperature.

Therefore, image patterns with different white cloudiness are formed on such a recording medium, and by projecting these, when the screen is white, a black projected image on a white background can be obtained.

The present invention will be explained below by way of examples. Note that both "parts" and "%" are based on weight.

Example 1 Behenic acid on a 75 μm thick polyester film
4 parts stearyl stearate 1 part tetrahydrofuran
A solution consisting of 92 parts was applied with a wire bar and dried by heating to form a heat-sensitive layer with a thickness of 15 μm. On top of that, a transparent electrode coating liquid (Catalyst & Chemical Industry Co., Ltd.) made by dispersing In-doped tin oxide powder in isophorone is added.
ELCOM-P1301) was coated using a wire bar and dried by heating to form a transparent conductive layer with a thickness of 4 μm. Next, a solution consisting of 95 parts of tetrahydrofuran was applied using a wire bar, and heated and dried to a thickness of 5 parts.
A heating layer of μm was provided. Furthermore, a solution consisting of 0.2 parts of a curing agent (for the same as above) and 10 parts of dioxane was applied with a wire bar, and dried by heating to a 0.0% hardening agent.
A protective layer of polysiloxane graft polymer having a thickness of 5 μm was provided.

Next, the recording medium thus produced was set in the apparatus shown in FIG. 5, and image formation and projection were performed.

First, the entire recording body is heated to about 65°C using a heat roller 16 to make the heat-sensitive layer transparent, and then a current of 1 mA per unit signal electrode is applied to the protective layer surface for 10 minutes using a power source C and a recording electrode B.
When the voltage was applied at intervals of 0 microseconds, the portion of the heat-sensitive layer where the current flowed (current-carrying portion) became cloudy. Subsequently, when the projection image thus formed was projected onto a screen using the light source 11, a clear projected image with high contrast was obtained. After that, this recording medium is heated by a heat roller 16 for approximately 650 mm.
When heated to .degree. C., the projection image was erased and the recording medium returned to its transparent state.

Even after repeating the above operation several hundred times, no deterioration was observed in the recording medium, and a clear projected image equivalent to the initial image was obtained.

Effects As described above, by using the projection image forming apparatus of the present invention, a clear projection image with high contrast can be formed with high sensitivity even if image formation is performed repeatedly. Further, by increasing the pixel density of the recording electrode, higher resolution is also possible. Furthermore, since the recording medium can be used repeatedly, the cost of forming images is low. Furthermore, it is easy to increase the area, and by providing a color filter layer on the recording medium, it is possible to have multiple colors.

[Brief explanation of the drawing]

=16- FIG. 1 is a schematic diagram of the projection image forming apparatus of the present invention, and FIG.
The figure is an explanatory diagram of the principle of image formation in an example recording medium used in the present invention, FIG. 3 is a modified view of the recording body, FIG. 4 is a configuration diagram of a recording electrode used in the present invention, and FIG. Invented device includes image erasing mechanism and overhead projector
FIG. A...Recording body B...Recording electrode C...Power source 1...Transparent support 2...Thermosensitive layer 3...
Transparent conductive layer 4... Current heating layer 5... Protective layer 6... Signal electrode 7... Return electrode
8...Color filter layer 9...Resin mold 11...Light source 16...Heat roller for image erasing 1 Figure 2 Figure 3 Box 4 Figure 6 = wo-kun product ratio). [Kaku Ninini 11' ■---111111

Claims (1)

[Claims] 1. A recording body in which a heat-sensitive layer whose light transmittance changes reversibly depending on the temperature, a transparent conductive layer, and an energized heating layer are sequentially provided on a transparent support, and an electric current is applied to the surface of the recording body. A projection image forming apparatus includes a recording electrode that supplies current to a predetermined location on a recording medium according to a signal, and a power source that supplies current to the recording electrode.