JPH05185792A - Display device - Google Patents

Abstract

PURPOSE:To obtain a display device which is capable of reducing the quantity of dust generated during the hand-writing and deletion of characters and symbols significantly compared to the quantity generated when a conventional display device is used, and can be used in a clean room. CONSTITUTION:A specified voltage is applied to an area between a transparent electrode 12 and an electrode 14. The entire surface of an ordinary thermochromic layer 11 does not allow permeation of light, and a photoconductor layer 13 is highly resistive so that almost no electric agent generates. If a character is written on a display surface 2 using a thermal pen, the temperature of the surface rises with the increased light permeability of the thermochromic layer 11, and consequently, the track of the thermal pen becomes visible. After that, the corresponding part of the photoconductor layer 13 to the track receives light from an outer area, and the electric resistance of the corresponding part increases to generate an electric current between the transparent electrode 12 and the electrode 14. Next, the part which is now visible of the thermochromic layer 11 is heated by the electric current, and characters in the part which is visible no longer disappear and continue to be displayed due to a thermal feedback effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device capable of repeatedly displaying handwritten characters, symbols and the like, and more particularly to a display device in which the amount of dust generated is reduced.

[0002]

2. Description of the Related Art Conventionally, as a device capable of handwriting and erasing characters, symbols and the like and capable of repeatedly displaying such handwritten characters, numbers, symbols and the like, writing characters and the like on a display board with a black ink etc. There is known a so-called white board or the like in which characters are written on a display board with a blackboard or a felt pen.

[0003]

However, in the above-mentioned display device such as a blackboard or a whiteboard, since characters or the like are written on the display plate with a black ink or a felt pen, especially when erasing these characters or the like, Black ink, ink, etc. are powdered and scattered. For this reason, there is a problem in that the amount of dust floating in the room is significantly reduced, and it cannot be practically used in a so-called clean room in which an environment in which almost no dust exists is realized.

The present invention has been made in response to such a conventional situation, and the amount of dust generated during handwriting and erasing of characters and the like can be greatly reduced as compared with the prior art, and in a clean room or the like. The present invention is intended to provide a display device that can be used in.

[0005]

That is, in the display device of the present invention, the light transmittance or the hue of the contact portion with which an object having a high temperature is in contact is changed, and the first contact portion is made visible. And the second layer sandwiching the second layer and the second layer configured so that the electric resistance of the corresponding portion decreases in accordance with the temperature change or the light transmittance change of the first layer. An electrode that is provided and selectively generates a current in a portion of the second layer where the electric resistance is reduced, and selectively heats a corresponding portion of the first layer. ..

[0006]

In the display device of the present invention having the above structure, when a character or the like is handwritten by an object having a high temperature such as a hot pen,
The light transmittance or hue of the corresponding portion of the first layer changes, and these characters and the like are visualized. The characters and the like visualized in this way disappear with a decrease in temperature, but in the display device of the present invention, in response to such a change in the first layer, the corresponding portion of the second layer is changed. The electrical resistance is reduced and a current is generated in this part. As a result, the visualized portion of the first layer is heated, the transmittance of light or the change in hue is maintained, and characters, symbols, and the like are displayed continuously.

Therefore, unlike the conventional display device, characters and the like can be continuously displayed without using black ink, ink or the like. Therefore, the amount of dust generated at the time of handwriting and erasing can be significantly reduced as compared with the related art, and it can be used, for example, in a clean room.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the display device of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall configuration of a display device according to an embodiment of the present invention. As shown in the figure, the display device 1 is similar to a conventional blackboard or whiteboard,
It is formed in a desired shape, for example, a rectangular plate shape, and one surface thereof is the display surface 2. And it is formed into a pen shape,
The tip part has a predetermined temperature, such as a resistance heater,
By writing characters or the like on the display surface 2 with the hot pen 3 which can be heated to about 40 to 60 ° C., these characters or the like can be displayed.

As shown in FIG. 2, the display device 1 is constructed by laminating a plurality of layers, and these layers are arranged in order from the display surface 2 side to the protective layer 10 and the thermochromic layer 1.
1, transparent electrode 12, photoconductor layer 13, electrode 14, substrate 1
It is said to be 5.

The protective layer 10 is made of a transparent material having heat resistance to the above-mentioned temperature of the hot pen 3 and having a small friction and a high abrasion resistance. As such a material, for example, a fluorine-based polymer such as Teflon or FEP Teflon, a polyester-based resin typified by Mylar, or another polymer film is suitable.

In the case of this embodiment, the thermochromic layer 11 is constructed so that the light transmittance changes depending on the temperature, and does not transmit light at room temperature, but is transmitted through the protective layer 10 to the thermal pen 3. The heat is transmitted through the light, and the trajectory of the hot pen 3 is visualized.

The transparent electrode 12 is made of a transparent conductor,
For example, it is composed of an oxide electrode represented by an ITO electrode. The electrode 14 is composed of, for example, a vapor deposited film of aluminum, a printed electrode, or the like.

The photoconductor layer 13 is the thermochromic layer 1.
When the transmittance of the light of No. 1 is changed and the light is incident from the outside, the electrical resistance is reduced, and a current is generated between the transparent electrode 12 and the electrode 14. In this way, as a material that reduces the electric resistance in response to light, for example,
CdS polycrystals or crystals, and junction type semiconductors such as amorphous silicon are suitable.

The substrate 15 supports the above-mentioned layers, has poor thermal conductivity so as to retain the thermal feedback effect of the photoconductor layer 13, and is necessary for erasing characters and the like. It is a substrate with a good cooling effect. As such a substrate 15, for example, a laminate of polymer films can be used. In addition, this substrate 1
5 is preferably provided with cooling fins or the like so as to accelerate the release of heat.

In the display device 1 having the above structure, when displaying, a predetermined voltage is applied between the transparent electrode 12 and the electrode 14 in advance. In this state, the entire surface of the thermochromic layer 11 does not transmit light, the photoconductor layer 13 has high resistance, and no current is generated. Then, when a character or the like is written on the display surface 2 by the hot pen 3, the temperature of that portion rises, the light transmittance of the thermochromic layer 11 rises, and the trajectory of the hot pen 3 is visualized. Then, the portion of the photoconductor layer 13 corresponding thereto is exposed to the light from the outside, the electric resistance of the portion exposed to the light is reduced, and a current is generated between the transparent electrode 12 and the electrode 14. This electric current heats the visualized portion of the thermochromic layer 11, and due to this thermal feedback action, the letters and the like of the visualized portion are not erased and are continuously displayed.

When such heat is transmitted to the surroundings, the displayed contents may become blurred over time. In such a case, as shown in FIG. 3, for example, the photoconductor layer 13 is partitioned in a vertical direction by an insulating member 16 arranged vertically and horizontally to prevent heat from being transmitted to the surroundings, or a similar shape to the protective layer 10. Bleeding can be prevented by disposing the light shield 17 of FIG. Similarly, the thermochromic layer 11 can be partitioned. In such a case, since the display is digital, it is necessary to appropriately select the size of the partition depending on the sizes of the hot pen 3 and the display device 1.

On the other hand, when deleting the displayed contents,
When completely erasing, the application of the voltage between the transparent electrode 12 and the electrode 14 may be stopped, and when partially erasing, for example, a desired portion may be covered with something like a blackboard wipe,
It can be erased by blocking the light.

As described above, in the display device 1 of this embodiment,
Unlike the conventional display device, characters and the like can be continuously displayed without using black ink, ink, etc., and the displayed contents can be easily erased without rubbing the display surface 2. Therefore, the amount of dust generated at the time of handwriting and erasing can be significantly reduced as compared with the related art, and it can be used, for example, in a clean room.

FIG. 4 shows a cross-sectional structure of a display device 1a of another embodiment. In the display device 1a of this embodiment, a negative temperature coefficient resistance is used instead of the photoconductor layer 13 of the above-mentioned embodiment. A layer 13a is provided. This negative temperature coefficient resistance layer 1
3a is composed of a substance whose electric resistance decreases with an increase in temperature, for example, a semiconducting polycrystalline body typified by a thermistor, a junction type semiconductor or the like.

In the display device 1a thus constructed,
Since the negative temperature coefficient resistance layer 13a normally has a high resistance, no current is generated between the transparent electrode 12 and the electrode 14. Then, when a character or the like is written on the display surface 2 by the hot pen 3,
The temperature of that portion rises, the light transmittance of the thermochromic layer 11 rises, the locus of the hot pen 3 is visualized, and the heat of the hot pen 3 is transferred to the negative temperature coefficient resistance layer 13a. The resistance of the negative temperature coefficient resistance layer 13a decreases, and a current is generated in this portion. Then, due to the heat generated by this current, the thermochromic layer 11 and the negative temperature coefficient resistance layer 13a are heated, and the characters and the like in the visualized portion are continuously displayed without disappearing. When the resistance of the element is too low and the temperature is too high, it is necessary to insert a current control resistor or the like. In addition, as described above, in order to prevent bleeding due to heat being transmitted to the surroundings, it is effective to partition the negative temperature coefficient resistance layer 13a in a stepwise manner with an insulating member or the like.

Even in the display device 1a having the above structure,
It is possible to obtain the same effect as that of the above-described embodiment. Further, in the present embodiment, since the light transmittance of the thermochromic layer 11 does not necessarily need to change, the thermochromic layer 11 that changes its hue and is visualized,
For example, cholesteric liquid crystal or the like can be used.

[0023]

As described above, according to the present invention,
It is possible to significantly reduce the amount of dust generated during handwriting and erasing of characters, symbols, etc. as compared with the related art, and to provide a display device that can be used in a clean room or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a cross-sectional configuration of the display device of FIG.

FIG. 3 is a diagram showing a cross-sectional configuration of a modified example of the display device of FIG.

FIG. 4 is a diagram showing a configuration of a display device according to another embodiment of the present invention.

[Explanation of symbols]

 1 Display Device 2 Display Surface 3 Hot Pen 10 Protective Layer 11 Thermochromic Layer 12 Transparent Electrode 13 Photoconductor Layer 14 Electrode 15 Substrate

Claims (1)

[Claims] 1. A first layer configured to visualize the contact portion by changing the light transmittance or hue of the contact portion with which an object having a high temperature is in contact, and a temperature change of the first layer or The second layer is arranged so as to sandwich the second layer so that the electric resistance of the corresponding portion decreases in accordance with the change of the light transmittance, and the electric resistance of the second layer is A display device, comprising: an electrode that selectively generates an electric current in the reduced portion and selectively heats a corresponding portion of the first layer.