JPH02272421A - Image erasing device - Google Patents

Abstract

PURPOSE:To improve driving response and also to prevent an image from being miserased when the image formed on a sheet type image carrier which varies in light scattering state reversibly by heating is erased by heating by providing a means which varies the distance between a heating means and the surface of the sheet type image carrier. CONSTITUTION:The image is formed on the image carrier 1 by using the difference in light scattering state and moved by driving rolls 3 and 3' as shown by an arrow. Further, an erasing means 2 is constituted of a guide rail 2a, a base material 2b, and a plane heating body 2c and is movable in a direction perpendicular to the surface of the image carrier. The plane heater 2c performs heating operation required to erase the image on the image carrier at all times. When the image to be erased is moved, the erasing means 2 is put close to the image carrier 1 to erase the image. When an image to be left is moved, the erasing means 2 is put away from the image carrier 1 to stop the erasure.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an image erasing device that erases, by heating, an image formed on an image carrier due to a difference in light scattering state, the light scattering state of which is reversibly changed by heating. Regarding.

[Prior Art] Erasable image forming media using materials whose light scattering state can be reversibly changed by controlling heating and cooling, such as phase-separated polymers and polymeric liquid crystals, have been known. Since these are polymeric materials, they have the advantage of being easy to make thinner and larger in area, as well as being more durable, so they may be considered as large screen display media or still image output media for projection, etc. It is being done. In this case, recording is performed by heating and rapid cooling using a thermal head or laser beam, and erasing is performed by heating and slow cooling.

In addition, the image carrier is also sheet-like or endless belt-like.
Applications are being considered where many images are recorded on one sheet.

[Problem to be Solved by the Invention] Generally, to erase an image on a sheet-like or endless belt-like image carrier, a heating source such as a resistance heating element fixed to the image carrier is used as an erasing device. In order to improve the erasing speed, it is necessary to increase the heat capacity of the eraser, but even when the heat source of the eraser is turned off, the heat capacity is large. However, the temperature of the erasing device did not drop, making it difficult to erase only one image or a portion of a large number of images. In addition, in order to avoid this, there is a problem that the image density will decrease, unless a method such as providing sufficient space between images can be considered.

Unexploited Ill was developed to solve the problems of the prior art, and it is a method of printing an image formed by the difference in the light scattering state on a sheet-like image carrier whose light scattering state changes reversibly by heating. When erasing by heating, the drive response is improved by erasing 9 times without erasing, and the D
It is an object of the present invention to provide an image erasing device which prevents erroneous erasing when a large number of images are formed on an R carrier and improves recording density.

[Means for Solving the Problems] That is, one aspect of the present invention is an image erasing device that erases, by heating, an image formed on a sheet-like image carrier whose light scattering state changes reversibly by heating. There it is,
The image erasing device is characterized in that it has a heating means for heating the sheet-like image carrier, and a means for changing the distance between the heating means and the surface of the sheet-like image carrier.

The present invention will be explained in detail below.

In the present invention, the image carrier may be made of a material whose light scattering state changes reversibly by heating.

As such a material, for example, a phase-separated polymer or a polymer liquid crystal can be used.

Examples of phase-separated polymers include systems in which two or more types of amorphous polymers are mixed, and these change into a compatible state and a phase-separated state depending on the temperature. In a phase-separated state, the system separates into micro regions having a specific polymer composition, and if the light refraction and refractive index of each composition is different, light is strongly scattered at the interface of the micro regions. Therefore, the phase separation state is a light scattering state. On the other hand, in a compatible state, no such interface exists, so light is not scattered.

In addition, due to the change pattern of compatibility-phase separation depending on temperature, these phase-separated polymers have LC3T (Lower
Cr1tical 5solution Tempera
ture) type and IJC3T(l)pper Cr1t
ical 5solution Temperature
re) types, the former exhibits a phase-separated state on the high-temperature side and a compatible state on the low-temperature side, and the latter is the opposite. UC8T type includes, for example, polystyrene-polyisobutyne type, polystyrene-polybutadiene type, polypropylene oxytopolybutadiene type, etc.
Types include or are limited to polyvinyl chloride-polymethacrylate-n-hexyl system, styrene acrylonitrile comonomer-polymethyl methacrylate system, polyvinylidene fluoride-polymethyl acrylate system, etc. Not.

In addition, by slowly cooling these phase-separated polymers after heating, it is possible to change the state of compatibility or phase separation on the high temperature side to the state on the low temperature side. It has the characteristic that it can be retained even after cooling.

Furthermore, the polymeric liquid crystal that can be used in the present invention is a thermotropic liquid crystal, and nematic, smectic, or cholesteric types can be used as the intermediate phase. Polymer thermotropic liquid crystals have the advantage of not only being able to obtain a thin one-dimensional state, but also being easier to maintain a recording state than low-molecular liquid crystals.

For example, polymer thermotropic liquid crystals (hereinafter simply referred to as polymer liquid crystals) that can be used in the present invention are classified into the following two types.

■Mesogen groups, or relatively rigid and long atomic groups, or those connected by flexible groups.

■ Those with a mesogen group or a relatively rigid and long atomic group in the side chain.

These polymer liquid crystals can be used in combination with several different types of polymer liquid crystals. It is also possible to use a mixture of a polymer liquid crystal and a low molecular liquid crystal, or a mixture of a polymer liquid crystal and a polymer.

Specific examples of polymer liquid crystals are shown below, but the invention is not limited thereto.

e R: 0C11,.

R: 0Csllt R: CN Since these polymeric liquid crystals have the characteristic that they can maintain their structural state at temperatures below the glass transition point, the following recording modes are possible, for example.

Liquid crystal phase polydomain state ←−→isotropic state (light scattering state) (first non-scattering state to transparent state) This recording mode first converts a polymer liquid crystal into a liquid crystal phase or a polydomain consisting of many domains (domains). keep it in state. Next, after heating the polymer liquid crystal to a temperature above which it exhibits a monoisotropic phase,
Recording is performed by rapidly cooling the polymer liquid crystal to below the glass transition point and maintaining the polymer liquid crystal in an isotonic phase state.

The recording area can be returned to the initial polydomain state by heating the polymeric liquid crystal to a temperature near the temperature at which it exhibits an isokylic phase and then slowly cooling it. Further, it is also possible to reverse each state of first non-scattering and light scattering to set the recording mode.

An image carrier can be obtained by coating these materials as a recording layer on a substrate such as glass or film and, if necessary, providing a protective film on the ridges.

Images are recorded on the image carrier by applying heat to the recording layer using a thermal head, or by adding a light-absorbing dye to the recording layer or a layer adjacent to it and heating it by irradiation with light such as a laser beam. You may do so.

Further, in order to color the recorded image, a coloring material for color display may be added to the recording layer or a layer adjacent thereto.

Conventionally known semiconductor laser light absorption dyes and color display dyes are used as the light absorption dyes and color materials for color display, and these dyes may be mixed. In particular, dichroic dyes are effective for polymeric liquid crystals due to their compatibility.

In addition, full-color or multi-color images can be formed by patterning a recording layer to which two or more colorants are added in an array or random array in the surface direction of the image carrier. Something comes up.

Furthermore, using a color filter separately from the image carrier,
It is also possible to form color images.

On the other hand, in order to improve the durability of the image carrier, an ultraviolet absorber or an antioxidant may be added to the recording layer or a layer adjacent thereto.

The image formed on the image carrier as a difference in light scattering intensity can be recognized as a single image by projecting it onto a menlin using a backlight or reflected light, or by visually observing the scattered light. It comes.

The present invention is an erasing device for erasing an image formed on an image carrier as described in ``-'', in which a heating means for heating the image carrier and a distance between the surface of the image carrier and the heating means are varied. It is characterized by allowing

An image carrier having a recording layer made of a polymeric liquid crystal, a phase-separated polymer, or the like can be used particularly in the form of a sheet or an endless belt, and a large number of images can be recorded on one sheet or belt.

Image erasing can be done by applying heat pulses or light irradiation using a thermal head, etc., in the same way as during recording, or by heating with a heating means having a planar heating element with a certain heating area, a thermal roller, etc. There are many advantages to carrying out erasing, such as faster erasing speed and easier to obtain slow cooling conditions.

In particular, in the case of a sheet-like or endless belt-like image carrier, one image may be recorded or displayed, and it may be necessary to erase the image while moving the image carrier.
Further improvements in erasing speed are expected.

Therefore, it is possible to stably supply heat to the image carrier by increasing the size of the heating means and its heat capacity, or whether increasing the size of the heating means is disadvantageous in terms of device configuration. In addition, an increase in heat capacity deteriorates the driving response of the heating means, and conversely there are disadvantages such as a decrease in erasing speed and erroneous erasing of images due to residual heat.

The image erasing device of the present invention is characterized in that the distance between the heating means and the surface of the image carrier is changed, thereby making it possible to prevent adverse effects caused by deterioration of drive responsiveness due to an increase in heat capacity.

In the present invention, the distance between the heating means and the image carrier surface may be any vertical or horizontal distance, and specifically, y
A9 Examples are shown in Figures (a) to (C).

In FIG. 9, reference numeral 1 indicates an image carrier, 21 indicates a heating means, and 22 indicates a moving direction of the heating means.

23 indicates the moving direction of the image carrier.

FIGS. 1(a) and 1(b) are explanatory diagrams showing an example of an image erasing device of the present invention. In FIG. 1(a), an image is formed on the image carrier l due to the difference in the light scattering state.
It is moved in the direction of the arrow by the drive roller 3.3'. The erasing means 2 includes a guide rail 2a, a base material 2b, and a planar heating element (hereinafter referred to as a planar heater) 2c, and is movable in a direction perpendicular to the surface of the image carrier.
The surface heater 2c always performs heating necessary to erase the image on the image carrier. When the image to be erased moves, the erasing means 2 is moved closer to the image carrier 1 to erase it. If the image you want to keep moves, please refer to Figure 1 (
As shown in b), erasing can be stopped by separating the erasing means 2 from the image carrier 1.

As the form of the image erasing device in the present invention, a single movable surface heater may be used;
), there is an erasing device that uses a large number of movable surface heaters 2c, and as shown in FIG. 3(b), there is an erasing device that uses surface heaters 2C arranged in a belt shape. This is more effective because the interval between images formed on the image carrier can be made smaller.

[Function] According to the present invention, there is provided an image erasing device that erases, by heating, an image formed on a sheet-like image carrier made of a polymeric material whose light scattering state changes reversibly by heating. It is characterized by changing the distance between the heating means for heating the sheet-like image bearing member and the surface of the image bearing member and the heating means, thereby performing erasing.

This improves drive responsiveness and prevents erroneous erasure when many images are formed on the image carrier.
This also made it possible to improve recording density.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Embodiment 1 FIG. 4 is a block diagram of a color image display device using the image erasing device of the present invention as a unit. This display device is
A recording section consisting of a thermal head 5, an image carrier belt 6,
Color filter 7, Fresnel lens 8. A display section consisting of a backlight 9, a plurality of striped surface heaters 1 movable in a direction perpendicular to the feeding direction of the ttrl holder.
Image erasing unit consisting of 0, drive roller 11.12.1:
1 and an image carrier belt 6.

The image carrier belt 6 is a polyester sheet with a thickness of 50 mm and 1 mm.
F is a polymer liquid crystal 20 represented by the following structural formula (I).
A solution prepared by dissolving the heavy part in 100 parts by weight of dichloroethane was applied using a wire bar, and after heating and drying this at 90°C for 15 minutes, the polymer liquid crystal was dissolved into a liquid crystal phase polydomain-like fM.
It is held in a white light scattering state.

It was obtained by forming it into an endless shape. The layer thickness of the polymer liquid crystal layer on the image carrier belt was 8 μm.

The drive roller 12 is driven by a motor (not shown), and
All other means were operated by mechanical components or electrical or electronic components (not shown).

First, when writing an image, the drive roller 12 is driven in the direction of the arrow, and when an image signal is output to the thermal head (multi-head) 5 by a facsimile signal from another facsimile machine, the image carrier belt 6 is heated. An image-shaped transparent part pattern is formed in the exposed area.

Through this operation, the image-like transparent pattern for one page of A4 size is sequentially formed and then stopped at the display section 14.

In the display section 14, due to the difference in the scattering transparency state of the image carrier, a beautiful color image is displayed as shown in FIG. 2 and its explanation in combination with a color filter provided in the display section.

Furthermore, there was no change in this image even if it was left as is for 100 days.

The image was erased using a movable striped heater as shown in FIG. 3(a).

FIGS. 5(a) to 5(d) are explanatory diagrams showing the driving method of the erasing section. In the figure, first, as shown in FIG. 5(a), the distance between the image carrier and all the striped surface heaters 10a to 1fld is increased by a mechanical drive (not shown). If the polymer liquid crystal was not heated above its glass transition point, the image on the image carrier was not erased.

On the other hand, as shown in FIG. 5(c), the distance between the image carrier and all the striped surface heaters 10a' to 10d' is reduced, and the temperature of each striped surface heater is adjusted as shown in FIG. With this setting, the polymer liquid crystal layer 15 on the image carrier is heated to a temperature above the isoytic phase transition point and then slowly cooled down to a glass transition point or below, so that the polymer liquid crystal layer 15 returns to a light scattering state and the image I was able to erase the .

Furthermore, in this embodiment, since the surface heater for erasing is arranged in stripes, as shown in FIGS. It is also possible to sequentially change the distance between the surface heater and the image carrier.

By using such an erasing device, the drive response between erasing and non-erasing becomes faster, it becomes possible to use f/heat from a one-sided heater, and there is no erroneous erasing of the next screen due to the residual heat of the one-sided heater after erasing, and the boundary area can also be erased. Since it can be made narrower, recording density has also improved.

Example 2 In a color image display device having a recording section, a display section, and a *feeding section similar to those in Example 1, as shown in FIG. An erasing unit 8 was provided.

As shown in FIG. 8(a), when the temperature-controlled striped surface heaters 10a' to 10d' are not on the image rejection body side in the same way as in FIG. 1. They are sent away without being taken away.

Further, as shown in FIG. 8(C), when the striped surface heater was on the image carrier side, the image on the image carrier 2 was erased.

- On the other hand, as shown in FIGS. 8(b) and 8(d), since the belt is moved, the image interval may be small, and the recording density is improved.

[Effects of the Invention] As explained above, according to the present invention, an image formed by a difference in light scattering state on a sheet-like image carrier made of a polymeric material whose light scattering state changes reversibly by heating can be heated. This is an image erasing device that erases images by means of a heating means for heating the sheet-like image bearing member, and a means for changing the distance between the heating means and the image bearing member. Drive response is improved,
In addition, effects such as preventing erroneous erasure when a large number of images are formed on the image carrier and improving recording density can be obtained.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are explanatory diagrams showing an example of the image erasing device of the present invention, FIG. 2 is an explanatory diagram showing the principle of color display, and FIGS. 3(a) and (b) are An explanatory diagram showing another example of the image erasing device of the invention, FIG. 4 is a configuration diagram showing the color display device of the first embodiment, and FIGS. 5(a) to (d) show a driving method of the erasing section of the first embodiment. FIG. 6 is an explanatory diagram showing the temperature conditions of the erasing section in Examples 1 and 2, FIG. 7 is a configuration diagram showing the color display device in Example 2, and FIGS. 8(a) to (d) ) is an explanatory diagram showing the driving method of the erasing section in Example 2, and FIG. 9(a)
-(c) are explanatory diagrams showing examples of the moving direction of the heating means with respect to the surface of the image carrier. l... Image carrier 1a1.・Recording section tb...
- Erasing section 2... Erasing means 2a... Guide rail 2b... Base material 2C... Surface heater 33', 11.12.13... Drive roller 5.
...Thermal head 6...Image carrier belt 7...
・Color filter 8...Fresnel lens 9...
Backlight 10, lOa ~IOe, loa'~IOe'-
Striped surface heater 14...Display section I5...Polymer liquid crystal layer 16...Light scattering section 17...Light'A passing section 1
8... Bell 1-shaped erasing section 20... Polyester substrate 21... Heating means 22... Moving direction of the heating means 23... Moving direction of the image carrier

Claims (7)

[Claims] (1) An image erasing device that erases, by heating, an image formed by a difference in light scattering states on a sheet-like image carrier whose light scattering state changes reversibly by heating, the sheet-like image carrier being heated. An image erasing device comprising a heating means and a means for changing the distance between the heating means and the surface of a sheet-like image carrier. (2) The image erasing device according to claim 1, wherein the sheet-like image carrier has a recording layer made of a polymeric material. (3) The image erasing device according to claim 2, wherein the polymer material is a polymer liquid crystal. (4) Claim 1, wherein the heating means comprises an assembly of a plurality of striped planar heating elements, and has means for independently changing the distance between the planar heating elements and the surface of the sheet-like image carrier.
The image erasing device according to any one of items 3 to 3. (5) The image erasing device according to claim 4, wherein the temperatures of at least two or more of the plurality of planar heating elements are adjusted to be different from each other. (6) The image erasing device according to any one of claims 1 to 3, wherein the heating means is a rotating belt-shaped heating means having a heating element. (7) The image erasing device according to claim 6, wherein the temperature of the heating element is adjusted to be different in the belt conveyance direction.