JPH07294966A - Display device - Google Patents

Abstract

PURPOSE:To simplify construction, to facilitate production and to make control of image display and erasing easy by providing a display device with electrode wires across resistance film. CONSTITUTION:The surface of a substrate 15 is provided with a glazed glass layer 16 and the electrode wires 17 are arranged at nearly equal intervals in one direction on the surface of the glazed glass layer 16. The resistance film 18 is applied on the surface of the glazed glass layer 16 contg. the electrode wires 17. The electrode wires 19 are arranged nearly at equal intervals in a direction perpendicular to the longitudinal direction of the electrode wires 17 on the surface of the resistance film 18. Further, a thermosheet 20 is tightly adhered and fixed over the entire part of the surface of the resistance film 18 including the electrode wires 19 by using an adhesive, etc. Currents flow in order of the electrode wires 17 to the resistance film 18 to the electrode wires 19 (or reverse therefrom) when the electrode wires 17, 19 are energized selectively according to image signals. Heat is then generated in the regions (heat generating element points) of the resistance film 18 held between the electrode wires 17 and 19 and the heat is transmitted to the thermosheet 20 mainly via the electrode wires 19, by which the regions corresponding to the thermosheet 20 is discolored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to a heat driven display device.

[0002]

2. Description of the Related Art Conventionally, as a display device of this type, as disclosed in Japanese Patent Publication No. 60-33254, for example, a line thermal head and a thermo-sheet which moves relative to the head are used. So-called thermal displays are known.

FIG. 5 is a perspective view showing the structure of this thermal display. In the figure, 1 is a line thermal head, 2 is an endless thermo sheet, 3 is a feed roller for moving the thermo sheet 2 in the direction of arrow A, 4 is a color filter, 5 is a cooler, 6 is a fluorescent lamp and 7 Is a heater. A thermoreversible material is applied on the surface of the thermosheet 2. The color of this thermoreversible material reversibly changes with temperature. That is, such a material has a hysteresis characteristic in the temperature concentration characteristic.

FIG. 6 shows an example of characteristics of Ag ₂ HgI ₄ thermoreversible material. The thermal display utilizes this hysteresis characteristic to write (display) and erase images.
That is, in displaying an image, heat is applied to the thermo-sheet 2 moving at a constant speed by the line thermal head 1, and the heat-applied portion of the thermo-sheet 2 is discolored. When the image is erased, the thermo sheet 2 is forcibly cooled by the cooler 5 to recolor the portion to which the heat is applied.

Here, in order to increase the contrast of the displayed image and improve the visibility, the fluorescent sheet 6 is normally used to irradiate the thermosheet 2 from the back side of the thermosheet 2 to apply heat to the thermosheet 2. The resulting change in light transmissivity is taken out via the color filter 4.

A conventional display device is disclosed in Japanese Patent Laid-Open No. Sho 60
-208787 discloses a surface thermal display using a surface (two-dimensional) thermal head. A cross-sectional view of this surface thermal display is shown in FIG. In the figure, 8 is a glass substrate, 9 is X wiring, 10 is a heat insulating layer of polyimide or the like, 11 is a through-hole conductor, 12 is Y wiring, and 13 is a temperature indicating material layer having the characteristics shown in FIG. , And 14 are resistors.

To display an image, first, the X wiring 9 and the Y wiring 1
One resistor 14 is selected by selecting one from each of the two. Actually, the selection terminal of the X wiring 9 is O,
A voltage of 2 / 3E is applied to the non-selected terminal, a voltage of E is applied to the selected terminal of the Y wiring 12, and a voltage of 1 / 3E is applied to the non-selected terminal. As a result, E is applied to the selected resistor 14 and 1 / 3E is applied to the unselected resistor 14. Therefore, only the resistor 14 selected according to the image information is applied with a voltage that is three times as high as the other voltage, and as a result, the amount of heat generated is nine times that of the temperature indicator layer 1.
3 is locally heated and discolors.

[0008]

However, the thermal display using the line thermal head has the following problems. (B) Since this thermal display uses the line thermal head 1, it is necessary to move the thermal head 1 and the thermosheet 2 relative to each other, and therefore a predetermined time is required to form one screen. There is a problem.

(B) Moreover, in order to maintain the formed screen as it is, it is necessary to maintain the temperature state of the heat-applied portion and the non-heat-applied portion of the thermosheet 2. In order to maintain this temperature state in the state where the heat is applied once, it is necessary to maintain the discolored state of the thermosheet 2 by applying the heat once. In particular, the temperature inside the thermal display device is actually lower than the heat application temperature.

Therefore, in order to prevent the color reversion even in this state, the thermo sheet 2 exhibiting the hysteresis characteristic at a relatively low temperature is used, or the heat retention is performed in addition to the thermoreversible material applied to the thermo sheet 2. It is conceivable to mix a medium for use, or to provide the heater 7 to heat the inside of the apparatus to some extent as shown in FIG.

However, in the above case, when heat is repeatedly applied, the temperature inside the apparatus rises, which may cause discoloration of the entire surface of the thermosheet 2. Further, in the case of, the translucency of the thermosheet 2 is deteriorated. Furthermore,
In the case of, it is useful for preventing color reversion, but since it is necessary to forcibly cool with the cooler 5 in order to recolor,
Temperature control is extremely difficult.

(C) Further, since the fluorescent lamp 6 and the color filter 4 are required to improve the contrast, and the cooler 5 for restoring the color is required, the size of the apparatus becomes large.

(D) On the other hand, the surface thermal display having the structure shown in FIG. 7 has the following problems. Since the X wiring and the Y wiring need to be electrically connected by the conductor of the through hole passing through the temperature indicating material layer 13, the configuration and manufacturing are complicated. Moreover, since resistors corresponding to the number of dots are required, the configuration and manufacturing become complicated. Therefore, the cost is high.

Therefore, the present invention provides a display device which does not require relative movement of the thermal head and the thermo sheet, a color filter, a fluorescent lamp, a heater, a cooler, etc., and which is simple in structure and manufacturing and easy in controlling image display. The purpose is to provide.

[0015]

A display device according to the invention of the present application comprises an electrically insulating substrate, a plurality of first electrode lines arranged in one direction on one surface of the substrate, and the first electrode line. A resistance film formed on a surface including the electrode line of the first electrode, and the first film on the resistance film.
A plurality of second electrode lines arranged in a direction intersecting with the electrode lines and a surface provided with the second electrode lines, directly or through a protective film electrically insulated, and discolored by heat. A layer formed of a thermoreversible material, and an insulating layer provided between the first electrode lines or between the second electrode lines. A pair of electrodes, which are connected to one of the second electrode lines or a part of the second electrode line, are arranged on opposite sides of the resistance film, whereby a current passing through the resistance film is caused to flow, A portion of the resistance film through which an electric current is applied by the pair of electrodes forms a heating element point, and a region of the layer formed of the thermoreversible material corresponding to the heating element point is discolored.

[0016]

According to the invention of the present application, image display is performed as follows. Electrode lines provided on both sides of the resistive film are selected according to the image signal, and a voltage is applied. Then, the current flows from one electrode line to the other electrode line through the resistance film. As a result, the region of the resistance film (heat generating element) sandwiched by the energized electrode wires generates heat. This heat is applied to the layer of thermoreversible material via the electrode wire provided on the upper surface of the resistance film. Then, the region of the layer corresponding to the heat generating raw point is discolored. Furthermore, an insulating layer is provided between the electrode wires to prevent heat transfer from one electrode wire to an adjacent electrode wire. Also, leakage current is blocked.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of an embodiment showing a technology on which the present invention is based. In the figure, 15 is a substrate. The substrate is in an electrically insulating state and is made of, for example, ceramics, glass, plastic, or a metal whose surface is electrically insulated. Reference numeral 16 denotes a glaze glass layer, which is provided on the substrate 15. The substrate 15 and the glazed glass layer 16 form a base. The glazed glass layer 16 has heat retention. Reference numeral 17 is an electrode wire, which is arranged on the surface of the glaze glass layer 16 in one direction (parallel to the paper surface in the figure) at substantially equal intervals. Electrode wire 1
7 is attached to the surface of the glaze glass layer 16 by plating, etching or the like.

Reference numeral 18 is a resistance film. The resistance film 18 is applied on the surface of the glazed glass layer 16 including the electrode wires 17. The resistance film 18 is formed of, for example, tantalum nitride.
Reference numeral 19 is an electrode wire. The electrode wires 19 are arranged on the surface of the resistance film 18 at substantially equal intervals in a direction perpendicular to the longitudinal direction of the electrode wires 17. Each electrode wire 19 is formed by plating or etching. The region of the resistance film 18 sandwiched between the electrode wire 17 and the electrode wire 19 forms one heating element point.

Reference numeral 20 is a thermo sheet. The thermosheet 20 is formed by applying a thermoreversible material mainly on the surface of the substance on the sheet. This thermoreversible material is shown in FIG.
The one having the temperature-optical density characteristic as shown in (3) is used.
As can be seen by comparing FIG. 2 and FIG. 6, this characteristic is characterized by having a thermochromic region on the relatively high temperature side, and having excellent sensitivity to discoloration with respect to temperature (small heat retention). . Examples of such dyes include mercury iodide (Ag ₂
HgI ₄ ).

Thermo sheet 2 formed in this way
0 is adhered and fixed on the entire surface of the resistance film 18 including the electrode wire 19 by using an adhesive or the like. However, thermo sheet 2
0 has a color tone of blue, yellow, brown, etc., and it can be used by freely replacing it according to the way of operation as a display. Therefore, in such a case, the thermoseat 20 is provided so as to be removable.

Next, the operation will be described. First, when the electrode lines 17 and 19 are selectively energized according to an image signal,
The current flows in the order of electrode line 17 → resistive film 18 → electrode line 19 (or vice versa), and the region of the resistive film 18 (heat generating element) sandwiched between the electrode line 17 and the electrode line 19 generates heat. This heat is mainly transferred to the thermosheet 20 via the electrode wire 19.
Then, the corresponding area of the thermosheet 20 is discolored.

At this time, since the thermoreversible material of the thermosheet 20 has a small heat preservation property as shown in FIG.
The contrast of discoloration of the thermosheet 20 obtained by applying heat is extremely large. Therefore, there is no need for a fluorescent lamp or a color filter for obtaining an image by transmitted light as in the conventional case.
Therefore, according to this embodiment, an extremely excellent display surface can be obtained by natural light from the surface side.

The thermal discoloration temperature is on the relatively high temperature side,
Moreover, since the sensitivity of discoloration is excellent, there is also an advantage that a cooler for recoloring is not required. In the above operation, when the discoloration is maintained for a long time, the thermoseat 20
It suffices to repeat the application of heat to the material in a short time.

FIG. 3 is a sectional view of another embodiment showing the technology on which the present invention is based. In the figure, the same members as those shown in FIG. 1 are designated by the same reference numerals. Reference numeral 21 is a protective film. The protective film 21 is attached on the surface of the resistive film 18 including the electrode lines 19. The protective film 21 is made of, for example, Ta ₂ O ₅ or Si.
It is formed by O ₂ . The thickness of the protective film 21 is 2 to 3 μm
The degree is good. Reference numeral 22 is a layer of thermoreversible material applied directly on the protective film 21. Since the display operation of this structure is similar to the display operation of the structure of FIG. 1, the description thereof is omitted here.

As another structure, a transparent and thin protective film may be further provided on the thermosheet 20 shown in FIG. 1 or the layer 22 of the thermoreversible material shown in FIG. By doing so, writing and erasing on the surface of this protective film become possible.

In the above, the embodiments showing the technique on which the present invention is based have been described. The electrode wire 19 used in the above embodiment
Has a constant width over the entire length, but in order to reduce the transfer of heat generated at the heating element point to the adjacent heating element point via the electrode wire 19, the electrode wire intersecting the electrode wire 17 The surface area of the portion 19 may be large, and the surface area of other portions may be small.

Further, as shown in FIG. 4, on the same substrate 25 as the thermal display according to the above-described embodiment, the control circuit (shift register or driver) 2 which is a peripheral device thereof is provided.
3 and the matrix wiring part 24 may be provided.

FIG. 8 shows a sectional view of an embodiment of the present invention.
In the figure, the same elements as those shown in FIG. 1 are designated by the same reference numerals. In this embodiment, the resistance film 18
A heat insulating portion 29 having the same height as the electrode surface of the electrode wire 19 and having electrical insulation is provided between the adjacent and adjacent electrode wires 19.

The heat insulating portion 29 is for preventing a leakage current in the adjacent direction of the adjacent electrode wire 19 or the heat generating element and for insulating the heat diffusion. With this configuration, when a current is applied to one electrode wire, the heat generating elements along the adjacent electrode wires can be prevented from generating heat, and the heat generation can be better guided to the outside.

9 and 10 (a) to 10 (e) show another embodiment of the present invention. Of these, FIG. 9 is a perspective view with a part cut away, and FIGS.
FIG. 6 is a cross-sectional view taken along line -A, line BB, line CC, and line DD.
In this embodiment, as in the embodiment of FIG.
A heat insulating portion 29 is provided at an interval between each other (FIG. 9).
(A)). In addition, the space between the electrode wires 17 is also determined by the heat insulating portion 41.
Are provided (FIG. 9E).

Further, the resistive layer 42 of this embodiment comprises three layers 43, 44 and 45. The intermediate layer 44 is shown in FIG.
As shown in (c), it is a continuous layer of resistive material. In the upper and lower layers 43 and 45, as shown in FIGS. 9B and 9D, spot-like resistance substances 43b and 45b are arranged in the heat generating element positions in the insulating layers 43a and 45a. Are arranged so as to form a matrix.

The spot-like resistance materials 43b and 45b
Are continuous with the resistance layer 44. Therefore, at the position of the heating element point, the resistance material is continuous in the vertical direction to form the resistance element. As described above, when the insulators 43a and 45a are provided so as to surround the spot, it is possible to prevent the heat from diffusing from the selected heating element point to the surrounding area, and thus drive the selected heating element point. It can reduce the power required to

Alternatively, layer 43 or 45 or both may be omitted. The difference between FIG. 8 and the one in which both layers 43 and 45 are omitted is only in that the heat insulating portion 41 is provided.

11 (a) to 11 (d) show still another embodiment of the present invention. Of these, FIG. 7A is a plan view, and FIGS. 6B to 6D are BB line, CC line, and D- line.
It is a D line sectional view. This embodiment is generally shown in FIG.
And the same as the embodiment of FIGS. 10 (a)-(e),
A diode 51 is provided at each heating element. In this diode 51, one electrode, for example, the anode 51a, is connected to the electrode wire 17, and the other electrode, for example, 51b, is connected to the spot 45b of the resistive material.

The diode 51 is made of, for example, polysilicon, and is formed by depositing it by, for example, a CVD method, selectively doping p-type and n-type impurities, and etching it so as to have a desired pattern. You can The reverse biased pn junction has an Al layer 52.
Bypassed by. The electrode wire 17 is formed so that one side thereof is connected to the anode 51 a of the diode 51.

In the illustrated construction, each heating element is formed at a position where the cathode 51b of each diode 51 is exposed to the resistance layer and is connected thereto. Electrode wire 1
The insulating layer 45 on 7 prevents current from flowing directly from the electrode wire 17 to the resistive layer 44.

The circuit configuration of the matrix of the heating element points having the diodes is as shown in FIG. The role of the diode is to prevent heat generation at the non-selected heating element points. When the diode 51 is not provided, a small current flows through the resistance element of the heating element point that is not selected.

For example, it is assumed that the heating element point at the intersection of the electrode lines B3 and A2 is selected. Then, part of the current passing through the resistance element R23 at the intersection of B3 and A2 flows into the line B2 through the resistance element R22 at the intersection of A2 and B2. As a result, the unselected heating element points at the intersections of B2 and A2 generate heat. Providing the diode as described above avoids such undesired heat generation.

13 (a) to 13 (d) show still another embodiment of the present invention. Of these, FIG. 7A is a plan view, and FIGS. 6B to 6D are lines BB and C- of FIG.
It is a C line and DD sectional view. This embodiment is shown in FIG.
The anode of the diode 51 is connected to the electrode wire 17 on the lower surface thereof, which is almost the same as the embodiment of (a) to (d). Each electrode wire 17 is composed of a wide lower portion 17a and a narrow upper portion 17b continuous with the lower portion 17a, and the upper portion 17b is connected to the anode 51a at its upper surface.

FIGS. 14A to 14C show still another embodiment of the present invention. Of these, FIG. 7A is a plan view, and FIGS. 7B and 7C are lines BB and C- in FIG.
It is a C line sectional view. This embodiment is shown in FIG.
13 (d) and FIGS. 13 (a)-(d), but each diode 51 has p-type and n-type layers,
They differ in that they are stacked vertically. The lower end of the laminated body constitutes the anode 51d and is connected to the electrode wire 17. The upper end of the stacked body forms a cathode 51e and is connected to the resistance layer 44.

[0041]

As described above, according to the invention of the present application, the following effects can be obtained. (A) In the present invention, since the electrode wire is provided with the resistance film sandwiched therebetween, the structure is simple and the manufacturing is easy. Also,
Control of pixel display and erasure becomes easy.

(B) In the present invention, since the layer having the thermoreversible material (for example, thermosheet) is provided fixed to the heat generating portion, the heat generating portion and the layer having the thermoreversible material are moved relative to each other. There is no need.

(C) Since the thermoreversible material having a relatively high thermal discoloration temperature is used, it is possible to display an image with a large contrast without using a color filter, a fluorescent lamp, a heater, etc. Can be miniaturized.

(D) When a current is applied to one electrode wire, it is possible to prevent heat generation in the heating elements along the adjacent electrode wires. Therefore, the display becomes clear.

(E) In the invention of the present application, in addition to the above, a diode is further provided, and when a current is passed through one heating element, the current is passed through another heating element along the same electrode line. (Backflow) can be prevented from flowing.
Therefore, the display becomes clearer.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an embodiment showing a technology on which the present invention is based

FIG. 2 is a diagram showing temperature-optical density characteristics of a thermoreversible material.

FIG. 3 is a cross-sectional view of another embodiment showing the technology on which the present invention is based.

FIG. 4 is a diagram showing a structural example in which a display device and its peripheral circuits are provided on a base.

FIG. 5 is a perspective view of a conventional display device using a line thermal head.

FIG. 6 is a diagram showing temperature-optical density characteristics of Ag ₂ HgI ₄ .

FIG. 7 is a sectional view of a conventional display device using a surface thermal head.

FIG. 8 is a sectional view of an embodiment of the present invention.

FIG. 9 is a perspective view of another embodiment of the present invention.

FIG. 10 is a sectional view of another embodiment of the present invention.

FIG. 11 is a diagram showing still another embodiment of the present invention.

FIG. 12 is a diagram showing a circuit configuration of still another embodiment of the present invention.

FIG. 13 is a diagram showing still another embodiment of the present invention.

FIG. 14 is a diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 15 Substrate 16 Glazed glass layer 17 Electrode wire 18 Resistive film 19 Electrode wire 20 Thermosheet 21 Protective film 22 Layer of thermoreversible material 23 Control circuit 24 Matrix wiring part 25 Base 29 Heat insulating part 41 Heat insulating part 43a Insulator 45a Insulator 51 diode

Claims (3)

[Claims] 1. An electrically insulating substrate, a plurality of first electrode lines arranged in one direction on one surface of the substrate, and a resistance film formed on a surface including the first electrode lines. A plurality of second electrode lines arranged on the resistive film in a direction intersecting with the first electrode line, and a protection that is directly or electrically insulated on a surface including the second electrode line. A layer formed of a thermoreversible material that is discolored by heat, and an insulating layer provided between the first electrode lines or between the second electrode lines. A pair of electrodes connected to one of the first electrode lines and one of the second electrode lines or formed of a part thereof are arranged on opposite surfaces of the resistance film, and An electric current is passed through the resistance film, and the portion of the resistance film to which the electric current is applied by the pair of electrodes forms a heating element point. A display device, wherein a region of a layer formed of a thermoreversible material, the region corresponding to the heat generation point is discolored. 2. The display device according to claim 1, wherein a portion of the resistance film through which an electric current is passed by the pair of electrodes is made into a spot shape to form a heating element point. 3. The thermal head according to claim 1, wherein the heat generating element is connected to the first electrode wire via a diode.