JP2830084B2 - Card-shaped information display medium - Google Patents

Description

A. Field of the Invention The present invention relates to a card-shaped information display medium for displaying information by utilizing a phase change caused by heating and cooling a polymer liquid crystal material,
In particular, it relates to the configuration of a mechanism for deleting displayed information.

B. Summary of the Invention The present invention is directed to a card-shaped information display medium for displaying information by utilizing a phase change caused by heating and cooling of a polymer liquid crystal material. Is heated to heat the liquid crystal display layer so that information displayed on the liquid crystal display layer can be erased.

C. Background of the Invention For example, a credit card that has individual information recorded and can purchase and cash items without paying cash, a bank card that can withdraw cash from an account with an unmanned cash dispenser, Various card-shaped information recording media are widely used, such as a prepaid card in which a fixed fee is paid in advance and a telephone or a vehicle can be used up to the limit, a hospital management card in place of a patient's chart in a medical facility, and the like. .

However, since information is recorded on these card-shaped information recording media by magnetic or optical means, if the information is not read by a reproducing device, the recorded content can be directly visually confirmed. Can not.

Therefore, for example, these card-shaped information recording media are provided with a visual information display means capable of erasing and rewriting information, and the date and amount of payment for a credit card, and the remaining balance and transfer destination of an account for a bank card are provided. If the prepaid card can display the remaining balance and expiration date that can be used, and the hospital management card can display the payment amount at the counter and the next visit date, the card as an information recording medium will have more advanced functions. However, it is possible to provide the user with a remarkable benefit, for example, it is possible to prevent troubles such as inability to pay due to insufficient balance.

D. Problems to be Solved by the Invention As a technique created in view of such a situation and capable of realizing a visual information display that enables information to be erased and rewritten, for example, a technique disclosed by the present applicant is described. Wish
There is a technique using an erasable thermal recording system described in the specification and drawings of JP-A-63-166199. The information display medium using such a technology, for example, provided on the substrate of the card-shaped recording medium is provided an aluminum vapor-deposited film serving as a reflective layer, a liquid crystal display layer is disposed on the aluminum vapor-deposited film,
A protective layer is provided on the liquid crystal display layer to form a thermally responsive display section. The liquid crystal display layer is mainly composed of a polymer liquid crystal material that undergoes a reversible phase change by heating and cooling,
It exhibits the following properties in response to heat applied from the outside. In other words, under the condition that the whole is in a state of a cloudy liquid crystal glass phase at room temperature, the temperature is relatively rapidly increased to an isotropic phase transition temperature, and then a relatively rapidly cooled portion is generated. Since such a portion is maintained in a transparent isotropic amorphous phase state, the light transmitted through the transparent portion is reflected by the aluminum vapor-deposited film as the reflective layer and is visually recognized. Are visually distinguished from the surrounding cloudy part in the state of the liquid crystal glass phase. In addition, when the entire structure is heated to the isotropic phase transition temperature and then gradually cooled under the condition that the entire structure is in the isotropic amorphous phase, the entire state is maintained in the liquid crystal glass phase. It becomes cloudy and the information display is erased.

When heat from the outside is applied to the liquid crystal display layer constituting the heat responsive display section of such a card-shaped recording medium so that information is displayed, a plurality of the heat responsive display sections contacting the surface corresponding to the heat responsive display section. A display writing head having an array of heating elements is used, and when heat is applied from the outside so that the displayed display is erased, the display writing head contacts the surface corresponding to the heat-responsive display section. A display erasing head having a heating unit to be used is used. When information is actually displayed or erased on the thermal response display section, the thermal response display section of the card-shaped recording medium and the display writing head or the display erasing head are in relative contact with each other. The display is moved, and the thermal response display section is scanned by the display writing head or the display erasing head.

As described above, on a card-shaped recording medium having a thermally responsive display section including a liquid crystal display layer, display writing provided for displaying and erasing information on the thermally responsive display section. Of the head and the display erasing head, the display erasing head should play a role of causing the liquid crystal display layer constituting the thermally responsive display section to be heated to the isotropic phase transition temperature and then gradually cooled. It is said.

However, the display erasing head is generally configured such that the heating section forms a linear body extending in the width direction of the heat responsive display section and scans the heat responsive display section in its length direction. Each part of the liquid crystal display layer constituting the part is heated to the isotropic phase transition temperature in the heating part of the display erasing head, and the heating part of the display erasing head is caused by the scanning of the display erasing head with respect to the thermal response display part. Is likely to cause a relatively sharp decrease in temperature after passing through the liquid crystal display layer. Therefore, the liquid crystal display layer may not be properly cooled and the display in the heat responsive display unit may not be efficiently and reliably erased. There is.

Further, when scanning is performed on the thermal response display section of the display / erase head, the heating section of the display / erase head surely contacts the surface corresponding to the thermal response display section of the card-shaped recording medium over the entire scanning range. When a non-contact portion is generated, an incompletely erased portion of the display is formed at the non-contact portion.

In addition, when the display is erased using the display erasing head in this manner, various inconveniences may occur. Therefore, without using the display erasing head, for example, storing the card-shaped recording medium in a thermostatic chamber or the like and performing liquid crystal display. Even if the display is erased by taking out the entire layer after it is heated to the isotropic phase transition temperature and then slowly cooling it, the device becomes large and complicated, and a large heat source is required. Disadvantages arise.

The present invention has been made in view of such circumstances, and as described above, in a card-shaped information display medium that displays information by utilizing a phase change due to heating and cooling of a polymer liquid crystal material, an erasing head and a constant temperature It is an object of the present invention to provide a card-shaped information display medium having a novel configuration capable of efficiently and reliably erasing a display without using a tank.

E. Means for Solving the Problems The card-shaped information recording medium according to the present invention, in order to achieve the above objects, a liquid crystal display layer mainly composed of a polymer material that reversibly changes phase by heating and cooling, A resistive layer which is laminated on the liquid crystal display layer and has a planar shape dedicated to erasure for erasing display information recorded on the liquid crystal display layer by heating the liquid crystal display layer, and is electrically connected to the resistive layer In addition, a pair of current-carrying electrodes having a contact portion connected to the current supply terminal exposed outside the liquid crystal display layer is provided.

F. Function When the card-shaped information display medium according to the present invention is loaded in the information recording / reproducing apparatus, the contact portion of the current-carrying electrode is electrically connected to the current supply terminal, and the current is supplied to the resistance layer. Then, the resistance layer laminated on the liquid crystal display layer generates heat and heats the entire liquid crystal display layer. By this heating, the temperature of the liquid crystal display layer is raised to a temperature equal to or higher than the isotropic phase transition temperature, and thereafter, the temperature is slowly lowered together with the heated resistance layer. Therefore, the slow cooling condition is satisfied, and the entire liquid crystal display layer becomes cloudy as described above, and the display is erased.

G. Embodiment Hereinafter, the present invention will be described in more detail with reference to the drawings, taking as an example a card-shaped recording medium provided with a thermal response display unit according to the present invention.

The information recording card 1 of the present embodiment includes a card-shaped recording medium,
For example, such as a conventionally used telephone card or a write-once optical card, an information recording unit on which information is recorded by magnetic or optical means is provided on the back of the card (not shown), As shown in FIG. 2, a rectangular thermal response display section 2 for visually displaying information is provided on a part of the card surface.

As shown in FIG. 1, which is a cross-sectional view taken along line AA of FIG. 2, the thermal response display section 2 has a resistance layer 4 on a card substrate 3.
And a liquid crystal display layer 5 mainly composed of a polymer liquid crystal material are sequentially laminated. The surface is covered with a transparent protective layer 6, and the contact portions 7a and 8a are exposed to the outside without being covered with the protective layer 6. The pair of conducting electrodes 7 and 8 are connected to both short sides of the resistance layer 4.

Further, description of the heat response display unit 2 having such a configuration will be given below.
Continue following its fabrication procedure.

In manufacturing the thermal response display section 2, first, the card substrate 3 is prepared. Examples of the material of the card substrate 3 include commonly used card substrate materials such as polyethylene terephthalate (PET), vinyl chloride, polymethyl methacrylate (PMMA), polycarbonate (PC),
Polyimide or the like can be used. The thickness of the card substrate 3 is, for example, 0,0 corresponding to a credit card.
7 mm to 0.8 mm or 188 μm or 250 μm equivalent to a telephone card
Etc. are appropriately set according to the purpose of use.

Next, a resistor, such as nichrome (NiCr), tantalum nitride (TaN), or a resistor paste, which is conductive and generates heat when energized, is coated on the upper card substrate 3 by coating, vapor deposition, sputtering, or the like to a thickness of 0.1 μm. The resistive layer 4 is formed by providing the resistive layer 4 with a thickness of about several hundred μm. In addition,
By adjusting the material, shape, thickness, and the like of the resistance layer 4, the electric circuit pattern, the resistance value, and the like of the resistance layer 4 can be set. The heating zone can be optimized.

In this example, the surface of the resistance layer 4 has a predetermined reflectance (for example, 15% or more), and also has a function of a reflection layer that reflects light so that a display can be visually recognized. As described above, since the resistance layer 4 is also used as a reflection layer for allowing a display to be viewed well, it is not necessary to separately provide a reflection layer such as an aluminum vapor-deposited film on the resistance layer 4. When manufacturing the thermal response display section 2, the number of manufacturing steps does not increase significantly, and the cost does not increase.

Further, both short sides of the resistance layer 4 are coated with, for example, gold (Au) or the like having good corrosion resistance and high conductivity and good workability by coating, vacuum vapor deposition, sputtering, or the like to a thickness of about 0.1 to several hundred μm. The current-carrying electrodes 7, 8 are formed by arranging them in a thickness. The current-carrying electrodes 7 and 8 can be obtained, for example, as described above. However, the manufacturing method, shape, position, and the like are not limited to the above examples. The resistive layer 4 may be formed after providing the layers 7 and 8, or a part of the card substrate 3 may be made conductive to function as a current-carrying electrode.

Furthermore, a display material mainly composed of a polymer liquid crystal material that reversibly changes the phase state by heating and cooling as described above and selectively takes a transparent state and an opaque state at room temperature is formed on the resistance layer 4. The liquid crystal display layer 5 is formed by coating with a thickness of about several μm to several tens μm. This polymer liquid crystal material includes, for example, the aforementioned Japanese Patent Application No. 63-1.
As described in No. 66199, side chain type polymer nematic liquid crystals such as cyanobiphenyl, azomethine, phenylbenzoate / azomethine or copolymers of cyanophenylbenzoate and methoxybiphenylbenzoate are suitable. Since the polymer nematic liquid crystal is a solid whose main chain and side chain thermal motions are frozen at room temperature,
The storage stability of the display is high, and it is stable against mechanical shock and bending distortion.

Finally, the protective layer 6 is formed by coating the entire surface of the information recording card 1 with a UV-curable acrylic hard coat agent to a thickness of several μm. At this time, the contact portions 7a, 8a of the energizing electrodes 7, 8 shown in FIG.
It is exposed so as not to be covered with the protective layer 6.

The thermal response display section 2 thus obtained has the card substrate 3 and the liquid crystal display layer 5 serving as an insulating section, and the contact sections 7a and 8a exposed to the outside are provided with the current-carrying electrodes 7 and 8 respectively. Are electrically connected to each other via the resistance layer 4 connected to the first electrode. The card substrate 3, the resistance layer 4, the liquid crystal layer
5. The protective layer 6 has heat resistance required for erasing and rewriting of information described later.

The thermal response display unit 2 can be easily disposed on the card substrate 3 by coating each layer as described above, and the thermal response display unit having the above-described configuration is provided on the surface of an already used information recording card. It can also be easily formed by sticking a film provided with 2.

Next, rewriting of the display of the thermal response display section 2 in this embodiment will be described. The rewriting of the display of the thermal response display section 2 is performed together with the rewriting of the information recording surface when the information recording card 1 is loaded into the information recording / reproducing apparatus in order to use the information recording card 1. .

First, when erasing information already displayed on the thermal response display section 2, as shown in FIG.
The current supply terminals 10, 11 built in the information recording / reproducing device are pressed against the contact portions 7a, 8a of 7,8. Then, a predetermined time from these current supply terminals 10 and 11 from time t ₁ to time t ₂ of the said resistive layer 4 via the energizing electrodes 7 and 8 as indicated by arrows in FIG. 3 shown in FIG. 4 A predetermined constant current _IE is given by T _E1 (about several hundred ms to several seconds). As a result, since the resistance layer 4 generates heat, the entire liquid crystal display layer 5 has an isotropic phase transition temperature (Tcl = 90 ° C. to 120 ° C.) in a short time as shown by a solid line I in FIG. The temperature is raised as described above, and the state changes from the liquid crystal glass phase to the isotropic phase via the liquid crystal phase. And the above time
When turned off the constant current I _E is at t _2, the temperature of the heated has been the resistor layer 4 drops slowly by natural cooling, the liquid crystal display layer 5 is gradually cooled accordingly. For this reason,
Time t ₃ when the liquid crystal display layer 5 is room T _R from the time t ₂
In the slow cooling time T _E2 , the liquid crystal display layer 5 shifts from the isotropic phase through the unstable isotropic phase to the liquid crystal phase by increasing the holding time here (annealing).
It is cooled and becomes a liquid crystal glass phase. In this state,
As described above, since the entire liquid crystal display layer 5 becomes cloudy,
The situation is erased.

For example, on the surface of a prepaid card such as a telephone card using a polyethylene terephthalate sheet having a thickness of 188 μm as a card substrate (the back side of the surface on which the magnetic recording section is provided), a resistance layer is formed of 3000 mm thick nichrome. Cyanobiphenyl-based side-chain polymer liquid crystal material on top
When a liquid crystal display layer is formed by laminating at 10 μm and a rectangular thermal response display section of about 25 mm × 85 mm is provided, the resistance between the current-carrying electrodes of gold provided on both short sides of the thermal response display section is provided. Is about 8Ω
By applying a potential difference of 5 V between the current-carrying electrodes for about 5 seconds, the liquid crystal display layer can be turned on at about 3 W.
The liquid crystal display layer was heated to 0 ° C. or higher, and then gradually cooled by natural cooling. The temperature of the liquid crystal display layer reached room temperature in about 5 seconds, and information could be erased.

When newly writing information on the thermally responsive display section 2 from which information has been erased, a display writing head 12 as shown in FIG. 6 built in the information recording / reproducing apparatus is used. The display writing head 12 is a so-called thermal head for writing information such as characters, numerals, figures, and the like as a dot row, and includes a plurality of thin stripes arranged in a row in the short side direction of the thermal response display section 2. (That is, a heating element). The display writing head 12 is pressed against one short side of the thermal response display section 2 as shown in FIG. 7 to move the information recording card 1 in the direction of the arrow in FIG. Head 12 is the thermal response display section 2
, The thermal response display section 2 is scanned in the long side direction toward the other short side. And at this time,
The display on the resistor 13 of the write head 12, one of the predetermined time T _W1 from the time t _4, as shown in FIG. 8 to time t ₅ (several ms~ several hundred ms approximately) in accordance with information to be written pulse predetermined pulse current I _W is supplied to. As a result, the temperature of the liquid crystal display layer 5 rises above the isotropic phase transition temperature (Tcl) in a short time as shown by the solid line II in FIG. It reaches the isotropic phase, and then when the current off at time t _5, the room temperature T _R is rapidly cooled in a short time T _W2 is deprived of heat to the resistive layer 4 and the like. Therefore, the time t ₅
In quench time T _W2 until time t ₆ for the liquid crystal display layer 5 is room T _R from the quench condition is satisfied the liquid crystal display layer 5
Transitions from the isotropic phase through the unstable isotropic phase to the isotropic amorphous phase, and information is recorded. In this recording state, since the written portion of the liquid crystal display layer 5 becomes transparent as described above, the underlying resistive layer 4 also serving as a reflective layer is exposed, and the surrounding liquid crystal glass phase (white turbidity) is exposed. The recorded information can be visually identified by the difference from the reflectance of (2).

In addition to this method, for example, a negative type mask provided with a transparent portion in accordance with information to be written is brought into close contact with the surface of the protective layer 6, and the liquid crystal display layer 5 is exposed to flash light through this mask. Then, the exposed portion may be heated to a temperature equal to or higher than the isotropic phase transition temperature (Tcl) and then rapidly cooled to form a transparent portion corresponding to the mask on the liquid crystal display layer 5. In this case, in order to efficiently convert light energy into heat energy,
As the material of the liquid crystal display layer 5, it is desirable to use the above-mentioned polymer liquid crystal material mixed with a photothermal conversion dye. When the writing method using the display writing head 12 is used as described above, the protective layer 6 is provided to prevent abrasion and thermal deformation of the thermally responsive display unit 2 due to contact with the resistor 13 which is a heating element. However, when writing by the flash light is performed, for the sake of simplicity, the protective layer 6 is used.
Can be omitted.

In the above embodiment, the thermal response display unit 2 according to the present invention is provided on a card-shaped recording medium such as a telephone card or a write-once optical card.
Was provided so that visual information could be displayed.However, the present invention is not limited to only the above-described embodiment, and may be applied to a visual information display card which can be simply erased and rewritten. The present invention can be applied, and the shape and the like are not limited to a rectangular shape, and can be applied to something other than a card.

H. Effects of the Invention In the card-shaped information display medium according to the present invention, when erasing the display, the resistance layer laminated on the liquid crystal display layer is energized through a current-carrying electrode to generate heat in the resistance layer. To heat the entire liquid crystal display layer. Therefore, unlike the case where the above-described display erasing head is used, the temperature of the liquid crystal display layer is raised at the same time as a whole, so that the efficiency is high. There is no fear that an erased portion is formed.

In addition, when the supply of current to the resistive layer is stopped, the temperature of the liquid crystal display layer slowly drops together with the heated resistive layer, so that appropriate slow cooling conditions can be satisfied even by natural cooling. Thus, the display on the thermal response display section can be reliably erased.

Also, in order to erase the display on the heat response display section,
It is only necessary to provide a mechanism for giving a predetermined erasing current to the energized electrode in the display recording / reproducing apparatus. Therefore, it is not necessary to use an erasing head or a thermostat having a complicated configuration. It is also useful for miniaturization and simplification.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of the information recording card to which the present invention shown in FIG. 2 is applied, FIG. 2 is a front plan view of the information recording card, and FIG. 3 is a thermal response of the information recording card. FIG. 4 is a schematic diagram for explaining an erasing operation of the display unit, FIG. 4 is a characteristic diagram of an erasing current given in the erasing operation, and FIG. 5 shows a temperature change of a liquid crystal display layer at the time of erasing and writing information. FIG. 6 is a perspective view showing the appearance of the display writing head, FIG.
FIG. 8 is a schematic diagram for explaining a write operation of the thermal response display section, and FIG. 8 is a characteristic diagram of a current applied at the time of the write operation. DESCRIPTION OF SYMBOLS 1 ... Information recording card 2 ... Thermal response display part 3 ... Card board 4 ... Resistive layer 5 ... Liquid crystal display layer 7, 8 ... Current-carrying electrode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/13 505 G02F 1/13 102 G02F 1/1333 G02F 1/133 G09F 9/00-9/46 G09G 3/18 B42D 15/10 B41M 5/26

Claims (1)

(57) [Claims] 1. A liquid crystal display layer mainly composed of a polymer material which undergoes a phase change reversibly by heating and cooling; and a liquid crystal display layer laminated on the liquid crystal display layer and recorded on the liquid crystal display layer by heating the liquid crystal display layer. A resistive layer having a planar shape dedicated to erasing the displayed image, and a pair of contacts electrically connected to the resistive layer and having a contact portion connected to a current supply terminal exposed outside the liquid crystal display layer. A card-shaped information display comprising an energizing electrode.