JP2001188248A - Liquid crystal display medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display medium used for a rewritable card or the like. SOLUTION: In a color liquid crystal display medium having three laminated layers of color display layers having a plurality of scanning electrodes 12 and signal electrodes 14, the display part 34 with pixels arranged in a matrix corresponding to the intersections of the scanning electrodes 12 and the signal electrodes 14 comprises a color display region 35A and a monochromatic display region 35B which performs only a monochromatic display. The monochromatic display is performed by writing the same data in each display layer. The signal electrodes 14 are preferably used in common in the color display region 35A and the monochromatic display region 35B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display medium used for a rewritable card or the like.

[0002]

BACKGROUND OF THE INVENTION Presently, paper cards are mainly used for name tags and recreational facilities tickets worn by visitors to companies and the like, but these are disposable. Therefore, the present inventors are studying a card having a liquid crystal panel having a memory property as a rewritable card so that it can be reused. It is also possible to perform color display on such a liquid crystal panel.

[0003] On the other hand, although objects to be displayed on the card can be photographs and characters, it is not necessary to display all of them in color. That is, a color display is preferable for a photograph, and a monochrome display is sufficient for character information.

Accordingly, the present invention provides a liquid crystal display medium having a color display area and a monochrome display area, which is suitable for use as a card or the like.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the liquid crystal display medium according to the present invention will be described with reference to the accompanying drawings. In FIG. 1, a thin plate-shaped liquid crystal display medium indicated by a reference numeral 2 in its entirety includes a light absorber 4 and a red display layer 6 (6R), which is sequentially laminated on the light absorber 4 and has substantially the same structure, a green color. Display layer 6
(6G), and a blue display layer 6 (6B) facing a user (not shown) (hereinafter, these members are collectively referred to as a liquid crystal panel 7). As best shown in FIG. 2, each display layer 6 is formed on a transparent upper substrate 8 and a transparent lower substrate 10 arranged at a predetermined interval from each other in the stacking direction, and on the upper substrate 8. , A plurality of parallel transparent electrodes (upper electrodes) 1 extending in the front-to-back direction in FIG.
2, a plurality of transparent electrodes (lower electrodes) 14 formed on the lower substrate 10 and extending in parallel in the left-right direction of FIG. 1 (that is, orthogonal to the upper electrodes 12), and the thickness of the liquid crystal display medium 2. Resin columnar structures 16 extending in the direction (stacking direction)
And a spacer (not shown) for keeping the thickness of each display layer 6 constant. Each display layer 6 also has a planar state (a selective reflection state that selectively reflects light of each color) and a focal conic state (a transparent state that transmits visible light) between the upper substrate 8 and the lower substrate 10. A cholesteric liquid crystal 18 which is switched between an intermediate state in which both are mixed is sandwiched. As the cholesteric liquid crystal 18, a chiral nematic liquid crystal obtained by adding a chiral agent to a nematic liquid crystal is preferable. Further, an orientation control film or an insulating film (not shown) may be provided on the transparent electrodes 12 and 14.

[0006] On the back surface of the liquid crystal panel 7 (the side opposite to the side facing the user), there is provided an electrode panel 20 which can be detachably connected to an external image writing device (described later). The electrode panel 20 is individually and electrically connected to the transparent electrodes 12 and 14 of each display layer 6 as described later in detail. As a result, in a state where the electrode panel 20 and the image writing device are connected, By applying a predetermined voltage to the specific upper electrode 12 and lower electrode 14 by the drive circuit of the image writing device, the liquid crystal cell located at the intersection of these upper electrode 12 and lower electrode 14 is brought into a planar state and a focal state. The state can be switched between a conic state and an intermediate state in which both are mixed. Note that, as is well known, these two states and the intermediate state are stably held without continuously applying a voltage.

[0007] Such a voltage application is generally performed by matrix driving. That is, as shown in FIG. 2, for example, a selection voltage is applied to one of the upper electrodes 12 (hereinafter, referred to as a scanning electrode) with respect to the electrodes 12 and 14 which are arranged so as to face each other at 90 degrees. In the applied state, a voltage is simultaneously or sequentially applied to all or some predetermined signal electrodes 14 among a plurality of lower electrodes 14 (hereinafter, referred to as signal electrodes) facing the scanning electrodes 12. Thus, the state of the liquid crystal 18 disposed between the scanning electrode 12 and the signal electrode 14 selected by applying the selection voltage is changed. By sequentially performing the above-described method on each of the scanning electrodes 12, a voltage is sequentially applied to the liquid crystal 18 in a matrix to perform display.

Further, a full-color image can be displayed on the liquid crystal display medium 2 by sequentially or simultaneously performing such matrix driving for each of the display layers 6R, 6G, and 6B.

Since the light absorber 4 is disposed at the lowermost layer in the direction in which the user observes, when all the liquid crystals 18 are in the focal conic state, light is emitted from each display layer 6R, 6R.
G and 6B are transmitted and absorbed by the light absorber 4,
The liquid crystal panel 7 displays black. Such a light absorber 4
For example, a black film can be used. Instead of the light absorber 4, a black paint such as black ink may be applied to the lowermost surface of the liquid crystal panel 7 to absorb light.

In FIG. 1, the red display layer 6R is in the planar state, the green display layer 6G is in the focal conic state, and the blue display layer 6B is in the mixed state of the planar state and the focal conic state (gray scale display is possible in this state). .) Is shown. The order of lamination of the display layers 6R, 6G, and 6B in the liquid crystal panel 7 is as follows.
It is not limited to FIG.

FIG. 3 is a schematic perspective view when the liquid crystal display medium 2 according to the present invention is formed in the form of a thin card 30. The card 30 has a housing 32 in which the blue display layer 6B is located on the front side and the electrode panel 20 is located on the back side. here,
Reference numeral 34 denotes, as shown in FIG. 4A, an intersection of the scanning electrode 12 and the signal electrode 14 as a pixel, and a display area for displaying by a set of the pixel. The card 30 is used for a visitor name tag, for example. When the card is used as a visitor card, the area 34 displays a photograph or name of the visitor.

More specifically, as shown in FIG. 5, the display section 34 has two display areas, namely, a color display area 35A and a monochrome display area 35 for performing only monochrome display.
B. For simplicity, FIG. 5 shows each electrode and its lead wire in a see-through state. In the example shown in FIG. 5, as the signal electrode 14, electrodes (C ₁ , C ₂ , C _{3 in the} figure) shared by the color display area 35A and the monochrome display area 35B and arranged at equal intervals are shown. I have. On the other hand, as the scanning electrode 12, the color display area 35A
Are shown (R ₁ , R ₂ , R _{3 in the} figure) and the electrodes 12B (R _{m + 1} , R _{m + 2} , R _{m + 3 in the} figure) in the monochrome display area 35B. When the card 30 is used as a card used for a visitor name tag, for example, a photograph of the visitor is displayed in the color display area 35A, and the visitor's name, company name, etc. are displayed in the monochrome display area 35B. Is displayed. The number of the color display areas 35A and the number of the monochrome display areas 35B may be two or more. Reference numeral 31 indicates a case where the writing or updating of the display contents is prohibited or permitted, or associated with at least one element selected from a scanning electrode, a signal electrode, and a plurality of terminals. It is an additional information recording unit used to identify the location and arrangement. Such additional information can be provided in various forms, for example, by providing a dent, hole, notch, barcode, or the like at a predetermined position such as an end of the card so as not to interfere with the use of the card. Can be.

As shown in FIG. 4D, the electrode panel 20
Has three regions, that is, a connection region 36 with the scanning electrode 12, a connection region 38 with the signal electrode 14, and a connection region 40 with the external image writing device, and these connection regions 36, 38, 40 Are provided with a plurality of terminals 42, 44, 46 arranged in a matrix for connection to the scanning electrode 12, the signal electrode 14, and an external image writing device.

More specifically, each display layer 6R, 6G, 6
B, a row of terminals 42R for connecting to the scanning electrodes 12 of the red display layer 6R, and terminals for connecting to the scanning electrodes 12 of the green display layer 6G, near the extraction portions of the scanning electrodes 12 arranged in a stepwise manner. Column 42G, scan electrode 1 of blue display layer 6B
Terminal rows 42 </ b> B for connecting to the scanning electrodes 12 are arranged in order in a direction substantially orthogonal to the scanning electrodes 12. as a result,
As shown in FIG. 4B, each scanning electrode 12 is electrically connected to each terminal 42 via a lead wire 49 (see FIG. 3) provided on the flexible substrate 48. Similarly, FIG.
As shown in (a), in the display layers 6R, 6G, and 6B, near the extraction portions of the signal electrodes 14 arranged stepwise,
Terminal row 44R for connecting to the signal electrode 14 of the red display layer 6R, terminal row 44G for connecting to the signal electrode 14 of the green display layer 6G, and terminal row 44B for connecting to the signal electrode 14 of the blue display layer 6B. Are arranged in a direction substantially orthogonal to the signal electrodes 14. As a result, as shown in FIG. 4C, each signal electrode 14 is electrically connected to each terminal 44 via a lead wire 49 (see FIG. 3) provided on the flexible substrate 48 (for easy viewing). , FIG. 4 (a) and FIG.
In (d), the flexible substrate 48 is omitted. In FIG. 3, the signal electrode 14 of the red display layer 6R is shown.
Only the flexible substrate 48 for electrically connecting the connection area 38 and the connection region 38 (see FIG. 4) is shown. ).

The lead wire 49 and the terminals 42 and 44 may be connected by thermocompression bonding using solder.
Alternatively, they may be connected via an anisotropic conductive film. Similarly, the lead wire 49 and the electrodes 12, 14 may be connected by thermocompression bonding using solder, or may be connected via an anisotropic conductive film.

Each connection terminal 46 for connection to an external image writing device may be connected one-to-one with a connection terminal 44 for connection to the signal electrode 14, as shown in FIG. As shown in FIG. 6B, three types of terminals 44 for connection to the signal electrode 14, that is, terminals 4 corresponding to each color
4R, 44G, and 44B may be commonly connected. In the former case, the image can be written reliably in a short time. In the latter case, as described later, the time for writing to the color display area 35A (the time required for inputting a voltage signal) becomes longer, but the number of connect terminals 46 to be connected to an external writing device can be reduced.

The reason why the latter is selected will be described with reference to FIG. FIG. 7 shows a relationship between the cholesteric liquid crystal and the luminous reflectance Y when a driving method of applying a voltage for selecting a display state to the liquid crystal after the cholesteric liquid crystal is once brought into the focal conic state is adopted. It is a graph shown. For example, to the luminous reflectance performs gradation display range from Y ₁ to Y _2, after resetting the cholesteric liquid crystal in the focal conic state, voltage may be applied between V ₁ of the V ₂ . When using a simple matrix drive as in the present embodiment, the intermediate voltage Vr of the V ₁ and V ₂ is applied to the scanning electrode, the signal electrode corresponding to the display state -Vc
It is preferred to apply a voltage from to + Vc. In general, the voltage Vc can be set to a value not large enough to change the display state even when only the voltage Vc itself is applied to the liquid crystal.
It becomes possible to share the signal electrode of each color. That is, when a selection voltage is applied to a predetermined scanning electrode in a color display area of a certain display layer to select it, and a predetermined signal voltage is applied to a signal electrode, the selection voltage of the selected scanning electrode and this scanning electrode Writing is performed by a composite voltage with the signal voltage of the signal electrode that intersects with the signal voltage. At the same time, the predetermined signal voltage is applied from the signal electrode to the pixels on the non-selected scan electrodes and other display layers that are not to be rewritten, but since this signal voltage is not so large as to change the display state, the pixels and The display of the other display layers will be maintained. Therefore, although the time required for writing a color image is longer than in the former case where the signal electrodes are made independent for each display layer, the color image can be written by sequentially writing to each display layer.

Regarding the connection with the scanning electrode 12, each connecting terminal 46 is connected to the scanning electrode 12A for color display in a one-to-one manner as shown in FIGS. 6 (a) and 6 (b).
The scanning electrodes 12B for monochrome display are three types of terminals 4
2, that is, terminals 42R, 42G, and 42 corresponding to each color
B is commonly connected.

Here, in the case of FIG. 6B in which the signal electrodes 14 of the respective colors are shared, an example of a method of applying a drive voltage to the scanning electrodes 12 and the signal electrodes 14 will be described. For the monochrome display area 35B, a voltage is simultaneously applied to the scanning electrodes 12B (R _{m + 1} , R _{m + 2} , R _{m + 3,} etc.) of the respective display layers 6R, 6G, 6B, and synchronized with this. By adjusting the voltage of the common signal electrode 14 in this manner, the liquid crystal cells of each display layer 6 constituting one pixel are all in a planar state (according to white display) or are all in a focal conic state (according to black display). Take one).

[0020] For the color display region 35A, the display layers 6R, 6G, 6B of the scanning electrodes 12A (such as R _1, R ₂₎
By individually applying a voltage to each pixel and adjusting the voltage of the common signal electrode 14 in synchronization with each voltage application, the liquid crystal cells of each display layer 6 constituting one pixel change their states independently. Thus, color display can be performed.

FIG. 8 shows an example of a method of connecting the image writing device to the electrode panel 20 of the liquid crystal display medium 2 (or card 30).
Shown in The image writing device 50 includes a flexible substrate 52
And a lead wire 54 arranged in parallel on the flexible substrate 52, and a connect terminal 56 connected to the lead wire 54.
And a panel 58 for penetrating the connect terminal 56 and fixing the connect terminal 56 at a predetermined position. An anisotropic conductor 60 for electrically connecting the connection terminal 46 and the connection terminal 56 by contacting the connection terminal 46 of the electrode panel 20 is provided on the side of the panel 58 facing the electrode panel 20. Is glued. The connection terminal 56 of the image writing device 50 and the connection terminal 46 of the liquid crystal display medium 2 (or the card 30) are positioned by a positioning means (not shown), and are connected via an anisotropic conductor 60.

As the anisotropic conductor 60, it is preferable to use one having elasticity called anisotropic conductive rubber. As described above, the form using an anisotropic conductor is preferable because the electrical connection of each terminal can be easily and reliably performed, and the connection and separation of the terminal can be repeatedly performed. Terminal 46 and connect terminal 56
May be configured so as to be in direct contact with each other so that electrical loss is minimized without electrical loss.

As described above, since the liquid crystal display medium 2 according to the present invention has the electrode panel 20 separately from the liquid crystal panel 7, a metal wiring having a low resistance can be used, and the connection is made over a wide area on the back surface. Since the terminal 46 can be arranged, connection with an external writing device is easy.

FIG. 9 is an external view showing an example of a writing device and an image recording system. The image recording system includes a card 30 which is a liquid crystal recording medium, and a writing device 50 which writes an image on the card 30, and a host device 70 which is an external device for transmitting image data to the writing device 50 as necessary. Is further included.

The writing device 50 has a housing 74 having a recess 72 for mounting the card 30. Recess 7
On the bottom surface of 2, a connect terminal 56 provided corresponding to the connect terminal 46 on the back of the card and an anisotropic conductor 60 covering the connect terminal 56 are provided. Card 3 due to the step of recess 72
0 is positioned at a position where both connect terminals face each other. A control circuit for receiving image data from the host device 70 is built in the housing 74. The concave portion 72 is provided with a sensor 76 for detecting additional information given to the card 30. As the sensor 76, for example, a sensor having mechanical or optical reading means may be used.

The housing 74 is provided with an openable / closable cover 78 made of a transparent rigid plate. By closing the cover 78, the card 30 is pressed by the anisotropic conductor 60, and the connection terminal 46 of the card 30 and the connection terminal 56 of the writing device 50 are electrically connected. In order to facilitate removal of the card 30 from the recess 72, for example, a notch 80 is provided at a part of the step of the recess 72 as shown in FIG. An extrusion mechanism may be provided.

FIG. 10 is a control circuit block diagram of the writing device 50. The control circuit includes a central control unit (CPU) 100 for overall control, a ROM 102 for storing programs and data, and a RAM for storing various data.
106, an interface 108 for receiving data transmitted from an external device such as the host device 70, a processing device 110 for performing predetermined processing on data obtained via the interface 108, a connect terminal 56 for writing to the card 30, A drive circuit 112 for applying a voltage to the connection terminal 56 based on image data is provided.

The CPU 100 controls the drive circuit 112 according to the received image data and writes an image on a liquid crystal display medium. At this time, based on the additional information detected by the sensor 76, the drive circuit 112 recognizes the electrode structure of the card 30 and controls the drive circuit 112 to perform writing by a drive method suitable for the electrode structure. Note that a storage medium containing image data may be built in the writing device main body 50, and data may be read from this storage medium and displayed.

For the liquid crystal display medium in which the signal electrodes of the respective display layers are connected to the common connect terminal as described above, the drive circuit 112 is controlled by the instruction from the CPU 100.
Performs writing of each layer sequentially.

As shown in FIG. 11, a writing device for automatically transporting and writing a card may be used. In this writing device, the card 30 inserted from the insertion port is transported by the transport roller 120 to the transport belt 122 and then transported by the transport belt 122 to the writing position.
Then, it is positioned at a position corresponding to the write terminal by a positioning mechanism (not shown). Here, a vertically movable write head 124 having a write terminal presses the card 30. At this time, the support member 126 supports the write head 124 from behind the transport belt 122. The card 30 on which the writing has been completed is transported by the transport belt 122
28 exits the writing device.

The above description relates to one embodiment of the present invention, and the present invention can be variously modified. For example,
In the above embodiment, the extraction of the scanning electrodes 12 and the extraction of the signal electrodes 14 are performed from different sides of the liquid crystal display panel. However, for example, the shape of the flexible substrate is devised to connect to the terminals at the same position. The scanning electrode and the signal electrode are taken out from the same side by a method such as connecting one of the signal electrode or the scanning electrode to the same side as the other by connecting the terminal to the terminal at the same position. It may be connected to a connection region 36 'for the scanning electrode and a connection region 38' for the signal electrode provided on one side of the panel 20 '.

As shown in Fig. 13, it is also possible to provide the scanning electrode drive IC 130 and the signal electrode drive IC 132 on the electrode panel 20 ". In this case, the cost of one card increases. However, the number of terminals 46 ″ for connecting to the outside can be greatly reduced, and a card for more reliable connection to the outside can be provided. Further, in this case, writing can be easily performed by a simple operation such as placing the liquid crystal display medium on a writing device without performing a troublesome operation such as connecting a connector. Therefore, it is advantageous for automation of writing.

In addition, through holes may be used to connect the electrode panel 20 and the electrodes (scanning electrodes and signal electrodes) of the liquid crystal panel 7 as shown in FIG. Specifically, the liquid crystal panel 7 is provided on the electrode panel 20 and the display layer 6.
Then, holes extending in the thickness direction are formed, and gold bumps or solder bumps 140 are passed through these holes to electrically connect the display layer 6 and the electrode panel 20.

Furthermore, in the above embodiment, voltage modulation is used to change the state of the liquid crystal. Alternatively, pulse width modulation may be used as is well known to those skilled in the art. Further, the liquid crystal material having a memory property is not limited to the liquid crystal material of the present embodiment, and other liquid crystal materials can be used as long as the liquid crystal material can display a multi-color image by being laminated.

[0035]

According to the liquid crystal display medium of the present invention, an area for performing only monochrome display is provided for a display object for which color display is not required. In this monochrome display, the same data is simultaneously written to three display layers. As a result, the required write data amount is reduced, and the write time can be shortened.

In order to realize a monochrome display, the scanning electrodes of each display layer in the monochrome display area may be connected to each other. In this case, each display layer can be selected at the same time, and monochrome display can be performed by writing once.

The signal electrodes of each liquid crystal display layer may be shared by the color display area and the monochrome display area. With this configuration, it is not necessary to provide a signal electrode independently for each region, and the electrode configuration provided on the display medium can be simplified.

If the plurality of liquid crystal display layers include a red display layer for performing red display, a green display layer for performing green display, and a blue display layer for performing blue display, it is advantageous for full color display.

When a plurality of terminals for connection to external signal output terminals connected to the scanning electrodes and signal electrodes of each display layer are provided on the back surface of the display medium, connection to an external writing device is facilitated. Can be done.

Further, since the signal electrodes are shared between the color display area and the monochrome display area, it is possible to rewrite only the color display area or the monochrome display area.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal display medium according to the present invention.

FIG. 2 is a perspective view showing each display layer of the liquid crystal display medium of FIG.

FIG. 3 is a perspective view showing a card on which the liquid crystal display medium of FIG. 1 is mounted.

FIG. 4A is a top view of the liquid crystal display medium of FIG. (B)
FIG. 5 is a cross-sectional view taken along the line IVb-IVb in FIG. (C)
Sectional drawing along the IVc-IVc line of FIG. (D)
FIG. 2 is a bottom view of the liquid crystal display medium of FIG. 1.

FIG. 5 is a diagram showing an example of a display unit of the liquid crystal display medium according to the present invention.

FIG. 6 is a diagram showing an example of connection between a connection terminal for connection to the outside and a terminal for connection to a scanning electrode or a signal electrode in the electrode panel.

FIG. 7 is a graph showing a relationship between the cholesteric liquid crystal and the luminous reflectance Y when a voltage for selecting a display state is applied to the liquid crystal after the cholesteric liquid crystal is once brought into a focal conic state.

FIG. 8 is a cross-sectional view showing an example of a method for connecting an external image writing device and an electrode panel of a liquid crystal display medium according to the present invention.

FIG. 9 is an external view illustrating an example of an image writing device and an image recording system.

FIG. 10 is a control circuit block diagram of the image writing device.

FIG. 11 is an external view showing a writing device for automatically transporting and writing a card.

FIG. 12 is a diagram showing another arrangement example of a connection terminal for connection to the outside and a terminal for connection to a scanning electrode or a signal electrode in the electrode panel.

FIG. 13 shows a scanning electrode driving IC and a signal electrode driving IC.
The figure which shows the electrode panel provided with.

FIG. 14 is an enlarged cross-sectional view of a connection region between an electrode panel and electrodes (scanning electrodes and signal electrodes) of a liquid crystal panel.

[Explanation of symbols]

2: liquid crystal display medium, 4: light absorber, 6: display layer, 8: transparent substrate, 10: transparent substrate, 12: scanning electrode, 14: signal electrode, 18: liquid crystal, 20: electrode panel, 30: card,
34: display unit, 35: display area, 42: terminal, 44: terminal, 46: connect terminal, 48: flexible substrate, 4
9: Lead wire, 50: Image writing device, 52: Flexible board, 54: Lead wire, 56: Connect terminal, 5
8: panel, 60: anisotropic conductor, 130: scan electrode drive IC, 132: signal electrode drive IC, 140: bump.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahide Ueda 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Yutaka Tsurumoto Azuchi-cho, Chuo-ku, Osaka-shi, Osaka 2-3-1-13 Osaka International Building Minolta Co., Ltd. (72) Inventor Koichi Koriyama 2-3-1-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd. (72) Inventor Masafumi Nishikaku F-term (reference) 2H089 HA04 HA21 HA32 KA17 KA20 QA16 RA11 TA03 UA09 2-3-1-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka

Claims (5)

[Claims] 1. A configuration in which a plurality of memory liquid crystal display layers including an upper and lower substrate, a plurality of scanning and signal electrodes intersecting with each other, and a liquid crystal layer sandwiched between the scanning and signal electrodes are stacked. In the multi-layer color liquid crystal display medium, a display unit in which pixels corresponding to intersections of the scanning electrodes and the signal electrodes are arranged in a matrix has a color display area and a monochrome display area. A liquid crystal display medium characterized by being written by writing the same image in a layer. 2. A structure in which a plurality of memory-type liquid crystal display layers including an upper and lower substrate, a plurality of scanning and signal electrodes intersecting each other, and a liquid crystal layer sandwiched between the scanning and signal electrodes are stacked. In the stacked color liquid crystal display medium having, a display unit in which pixels corresponding to the intersections of the scanning electrodes and the signal electrodes are arranged in a matrix has a color display area and a monochrome display area, and each of the monochrome display areas A liquid crystal display medium, wherein scanning electrodes of a display layer are connected to each other. 3. The liquid crystal display medium according to claim 1, wherein the signal electrodes of each of the liquid crystal display layers are commonly used in a color display area and a monochrome display area. 4. The liquid crystal display layer according to claim 1, wherein the plurality of liquid crystal display layers include a red display layer for performing red display, a green display layer for performing green display, and a blue display layer for performing blue display. The liquid crystal display medium according to the above. 5. The display medium according to claim 1, further comprising a plurality of terminals connected to external signal output terminals connected to the scanning electrodes and the signal electrodes of each display layer on the back surface of the display medium. 3. The liquid crystal display medium according to item 1.