JP2004029801A - Liquid crystal display and display system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display and a display system aiming at further power saving, using a reflection type liquid crystal having memory property with visible display at all times and having excellent visibility even in the outdoors. <P>SOLUTION: This display 10 is equipped with liquid crystal elements 100 constituting a display screen by using the reflection type liquid crystal having memory property. The display 10 is used as a sub-display of a personal computer 1. The liquid crystal display elements 100 stop power supply after turning on the screen, and an image is kept visible thereafter using the memory property and reflection characteristic of the liquid crystal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device using a reflective liquid crystal having a memory property and a display system including the liquid crystal display device.
[0002]
BACKGROUND AND PROBLEMS OF THE INVENTION
2. Description of the Related Art In recent years, display devices in which a display screen is configured using liquid crystals have become widespread. Various types of liquid crystal display elements are provided. As display elements having a memory property, reflection type elements using a ferroelectric liquid crystal or a liquid crystal exhibiting a cholesteric phase are known. A commonly used liquid crystal display element such as a TN type repeats writing of an image in a very short time cycle and performs so-called refresh driving for maintaining a display. On the other hand, the memory type liquid crystal display element retains the written image even after the application of the driving voltage is stopped, and is excellent in power saving.
[0003]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid crystal display device and a display system using a reflective liquid crystal having a memory function that can always view a display and has good visibility even outdoors, so as to further reduce power consumption. Is to provide.
[0004]
It is another object of the present invention to provide a liquid crystal display device capable of displaying contents corresponding to various data sources and easily maintaining confidentiality of display.
[0005]
Configuration, operation and effect of the present invention
In order to achieve the above object, a liquid crystal display device according to a first aspect of the present invention includes a liquid crystal display element having a display screen formed by using a reflective liquid crystal having a memory function, and a drive for writing an image to the liquid crystal display element. A circuit, a data processing device connected to the drive circuit, a power supply circuit for supplying power to the drive circuit and the data processing device, and the power supply after writing an image to the liquid crystal display element. Even after at least a part of the circuit and / or the internal circuit of at least a part of the data processing device is inactive, and the part of the power supply circuit and / or the internal circuit of the data processing device is inactive, the liquid crystal A control unit for maintaining an image in a visible state by utilizing a memory property and a reflection characteristic of the display element.
[0006]
The reflection type liquid crystal having memory properties used in the liquid crystal display device according to the first invention retains the image even after the power supply is stopped after rewriting the screen. After the writing is performed, at least a part of the power supply circuit and / or at least a part of the internal circuit of the data processing device are disabled. Further, even after a part of the power supply circuit and / or the internal circuit of the data processing device is made inoperative, the image is maintained in a visible state by utilizing the memory properties and the reflection characteristics of the liquid crystal display element. Thus, the display can be always viewed, the power consumption during standby can be suppressed, and the power saving effect can be further enhanced. In addition, since a reflective liquid crystal that performs display using external light incident on a screen is used, a backlight is not required, and not only the power saving effect is extremely high, but also excellent visibility is maintained outdoors.
[0007]
In the liquid crystal display device according to the first aspect of the invention, the liquid crystal display element may be configured such that the display screen is configured using liquid crystal obtained by adding a chiral dopant in a nematic liquid crystal at room temperature to a sufficient amount to exhibit a cholesteric phase. Good. By controlling the mixture ratio of the nematic liquid crystal and the chiral dopant, the display color tone can be finely adjusted, and the visibility is improved.
[0008]
Further, it is preferable that the liquid crystal display element is capable of halftone display, in which a liquid crystal layer is sandwiched between a plurality of scanning electrodes and a plurality of signal electrodes, and is driven in a matrix. The expressiveness of the display is improved.
[0009]
Further, it is preferable that the liquid crystal display element is capable of full-color display. With full-color display, display with good image recognition is possible.
[0010]
Further, the liquid crystal display element may be formed by laminating a plurality of display layers including a reflective liquid crystal having a memory property. Bright display is possible and full color display can be supported.
[0011]
Further, the liquid crystal display element may have an alignment control film provided on a substrate that sandwiches liquid crystal. It is possible to prevent the display characteristics from changing over time. This alignment control film is preferably not subjected to a rubbing treatment. The viewing angle dependency is reduced, and the visibility is improved.
[0012]
Further, the liquid crystal display device according to the first aspect of the present invention may include a reset key for instructing that the display screen of the liquid crystal display element be written in such a manner as to be filled with a single color and reset the screen. The screen can be reset when the user needs it to maintain confidentiality and prevent screen burn-in.
[0013]
A display system according to a second aspect is characterized by including a plurality of the liquid crystal display devices and a host device to which the plurality of liquid crystal display elements are connected. A display system having the various effects described above can be constructed.
[0014]
A liquid crystal display device according to a third invention is a liquid crystal display device, a driving circuit for the liquid crystal display device, a data processing device connected to the driving circuit, a receiving circuit for receiving an external signal, A slot for detachably holding a storage medium for storing image information to be displayed on the display element, and at least a part of an internal circuit of the data processing device in a state where the display of the liquid crystal display element is kept visible. The liquid crystal display device includes a control unit for setting an operation state and an openable and closable housing for accommodating the members and the unit, and the liquid crystal display element is invisible when the housing is closed.
[0015]
In the liquid crystal display device according to the third aspect of the invention, the provision of the receiving circuit and the slot for attaching and detaching the storage medium makes it possible to display the content corresponding to various data sources. In addition, since at least a part of the internal circuit of the data processing device is disabled in a state where the display is kept visible, power saving is achieved. Moreover, when the housing is closed, the liquid crystal display element becomes invisible, so that the confidentiality of the display to others can be easily maintained.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a liquid crystal display device and a display system according to the present invention will be described with reference to the accompanying drawings.
[0017]
(Configuration of display device, see FIGS. 1 to 4)
1 and 2 show the appearance of a display device 10 according to a first embodiment of the present invention. The display device 10 is used as a sub-display of the personal computer 1 and includes a support base 20, a support arm 30, a frame 40, and a full-color liquid crystal display device 100.
[0018]
The display device 10 displays fixed information that does not need to be frequently rewritten, for example, a schedule table, a calendar, a telephone directory, an address book, a memo, a map, and e-mail incoming information. By displaying these pieces of fixed information on the device 10 as a sub-display, the entire area of the display of the personal computer 1 can be effectively used to efficiently perform operations such as editing. The display device 10 may display an inactive window hidden under another window when displaying a multi-window, or may display a window that was closed last. A viewing image may be displayed. In any case, since the display device 10 can perform color display as described later, colorful and highly visible display can be performed.
[0019]
The frame body 40 has an attachment / detachment opening 41 for attaching / detaching the liquid crystal display element 100, and is attached to the support arm 30 via a rotation shaft 31 as shown in FIG. It can rotate as a fulcrum. FIG. 1 shows a case where the liquid crystal display element 100 is used in a vertically long state, and FIG. 2 shows a case where the liquid crystal display element 100 is rotated 90 ° and used in a horizontally long state. The rotation may be performed by the user rotating the frame body 40 by hand, or the rotation may be automatically performed by providing a drive mechanism including a motor on the rotating shaft 31.
[0020]
FIG. 3 shows a state in which the liquid crystal display element 100 is taken out of the frame 40, and FIG. 4 shows a mechanism relating to attachment and detachment. Specifically, the frame body 40 includes a rear fixing frame 42 and a front frame 43, and the front frame 43 is fastened / fixed to the rear fixing frame 42 by a fixing tool 44. At this time, the liquid crystal display element 100 is positioned by the positioning and pushing member 45 provided on the rear fixed frame 42, and the mounted state is detected by the sensor 46. Further, as described in detail below, the liquid crystal display element 100 has scanning electrodes and signal electrodes arranged in a matrix, and these electrodes are connected to the scanning driving IC terminal portion 133 and the signal driving IC terminal portion 134 at the time of mounting. Is electrically connected to the
[0021]
On the other hand, the liquid crystal display element 100 can be pushed out by the member 45 by loosening the fixture 44, and can be taken out from the attachment / detachment opening 41. As shown in FIG. 3, in the taken-out liquid crystal display element 100, an end of the electrode 114 is exposed on the front and an end of the electrode 113 (not shown in FIG. 3) is exposed on the back. Therefore, it is preferable to prepare a cover for protecting the electrodes 113 and 114. Since the liquid crystal display element 100 is thin and has a memory property, it can be taken out of the frame 40 and used like paper. If the electrode protection cover is formed of a hard material, the liquid crystal display element 100 is not mistaken for ordinary paper, and an accident such as being thrown into a shredder can be prevented. In addition, specific information may be printed on the edge (area other than the display screen) of the liquid crystal display element 100 in consideration of paper-like use.
[0022]
(Liquid crystal display element, see FIGS. 5 to 7)
Next, the liquid crystal display element 100 incorporated in the display device 10 will be described with reference to FIG. In the liquid crystal display element 100, a red display layer 111R for performing display by switching between red selective reflection and a transparent state is disposed on the light absorbing layer 121, and a display is performed thereon by switching between green selective reflection and a transparent state. A green display layer 111G to be performed is laminated, and a blue display layer 111B that performs display by switching blue selective reflection and a transparent state is further laminated thereon.
[0023]
Each of the display layers 111R, 111G, and 111B has a structure in which a resin columnar structure 115, a liquid crystal 116, and a spacer 117 are sandwiched between transparent substrates 112 on which transparent electrodes 113 and 114 are formed, respectively. An insulating film 118 and an orientation control film 119 are provided on the transparent electrodes 113 and 114 as needed. Further, a sealant 120 for sealing the liquid crystal 116 is provided on an outer peripheral portion (outside the display area) of the substrate 112.
[0024]
The transparent electrodes 113 and 114 are respectively drawn out to connect to an image processing apparatus. FIG. 5 shows a state in which the signal electrode 114 is connected to the connection terminal portion 134 via the anisotropic conductive rubber 143. Then, a predetermined pulse voltage is applied between the transparent electrodes 113 and 114 from the drive control unit. In response to the applied voltage, the display is switched between a transparent state in which the liquid crystal 116 transmits visible light and a selective reflection state in which visible light of a specific wavelength is selectively reflected.
[0025]
The transparent electrodes 113 and 114 provided on each of the display layers 111R, 111G and 111B are composed of a plurality of strip electrodes arranged in parallel with a fine interval therebetween, and the arrangement direction of the strip electrodes is perpendicular to each other. They face each other. Current is sequentially applied to these upper and lower strip electrodes. That is, a voltage is sequentially applied to each liquid crystal 116 in a matrix to perform display. This is called matrix driving. By performing such matrix driving sequentially or simultaneously for each display layer, a full-color image is displayed on the liquid crystal display element 100.
[0026]
Specifically, in a liquid crystal display element in which liquid crystal exhibiting a cholesteric phase is sandwiched between two substrates, display is performed by switching the state of the liquid crystal between a planar state and a focal conic state. When the liquid crystal is in the planar state, assuming that the helical pitch of the cholesteric liquid crystal is P and the average refractive index of the liquid crystal is n, light of wavelength λ = P · n is selectively reflected. In the focal conic state, when the selective reflection wavelength of the cholesteric liquid crystal is in the infrared light range, the light is scattered, and when it is shorter than that, visible light is transmitted. Therefore, by setting the selective reflection wavelength in the visible light region and providing the light absorbing layer on the side opposite to the observation side of the element, it is possible to display the selective reflection color in the planar state and display black in the focal conic state. In addition, by setting the selective reflection wavelength in the infrared light region and providing a light absorbing layer on the side opposite to the observation side of the element, light in the infrared light region is reflected in the planar state, but the wavelength in the visible light region is reflected. Is transmitted, so that a black display and a white display due to scattering in the focal conic state are possible.
[0027]
(Full color display)
In the liquid crystal display element 100 in which the display layers 111R, 111G, and 111B are stacked, the blue display layer 111B and the green display layer 111G are in a transparent state in which liquid crystals are in a focal conic arrangement, and the red display layer 111R is in a planar arrangement in the liquid crystals. By making the selective reflection state, a red display can be performed. Further, yellow display is performed by setting the blue display layer 111B in a transparent state in which liquid crystals are in a focal conic arrangement, and setting the green display layer 111G and the red display layer 111R in a selective reflection state in which liquid crystals are in a planar arrangement. Can be. Similarly, red, green, blue, white, cyan, magenta, yellow, and black can be displayed by appropriately selecting the state of each display layer between a transparent state and a selective reflection state. Furthermore, by selecting an intermediate selective reflection state as the state of each of the display layers 111R, 111G, and 111B, display of an intermediate color becomes possible, and it can be used as a full-color display element.
[0028]
The order of stacking the display layers 111R, 111G, and 111B in the liquid crystal display element 100 may be other than that shown in FIG. However, considering that the transmittance of the light in the long wavelength region is higher than that in the short wavelength region, the selective reflection wavelength of the liquid crystal contained in the upper layer is selectively reflected by the liquid crystal contained in the lower layer. When the wavelength is shorter than the wavelength, more light is transmitted to the lower layer, so that a bright display can be performed. Therefore, it is most desirable that the blue display layer 111B, the green display layer 111G, and the red display layer 111R be arranged in this order from the observation side (the direction of arrow A). In this state, the most preferable display quality can be obtained.
[0029]
(Various materials for display elements)
As the transparent substrate 112, a colorless and transparent glass plate or a transparent resin film can be used. Examples of the material of the transparent resin film include a polycarbonate resin, a polyethersulfone resin, a polyethylene terephthalate resin, a norbornene resin, a polyarylate resin, an amorphous polyolefin resin, and a modified acrylate resin. The characteristics of the resin film are high translucency, no optical anisotropy, dimensional stability, surface smoothness, friction resistance, bending resistance, high electrical insulation, chemical resistance, liquid crystal resistance, heat resistance What is necessary is just to select a material which has moisture resistance, gas barrier property and the like, and has necessary characteristics in accordance with the environment and use.
[0030]
As the transparent electrodes 113 and 114, a transparent electrode such as ITO (Indium Tin Oxide) can be used, and a metal electrode such as aluminum or silicon, or a photoconductive film such as amorphous silicon or BSO (Bismuth Silicon Oxide) is used. You can also. In addition, as for the lowermost transparent electrode 114, a black electrode can be used including the role as a light absorber.
[0031]
As the insulating film 118, an inorganic film such as silicon oxide or an organic film such as a polyimide resin or an epoxy resin is used so as to function also as a gas barrier layer, which prevents a short circuit between the substrates 112 and improves the reliability of liquid crystal. In addition, polyimide is a typical example of the orientation control film 119.
[0032]
The liquid crystal 116 preferably exhibits a cholesteric phase at room temperature, and in particular, a chiral nematic liquid crystal obtained by adding a chiral dopant to a nematic liquid crystal is suitable.
[0033]
A chiral dopant is an additive that has the effect of twisting the molecules of a nematic liquid crystal when added to the nematic liquid crystal. By adding a chiral dopant to a nematic liquid crystal, a helical structure of liquid crystal molecules having a predetermined twist interval is generated, thereby exhibiting a cholesteric phase.
[0034]
The chiral nematic liquid crystal has an advantage that the pitch of the helical structure can be changed by changing the addition amount of the chiral dopant, and thereby the selective reflection wavelength of the liquid crystal can be controlled. In general, as a term indicating the pitch of the helical structure of liquid crystal molecules, “helical pitch” defined by the distance between the liquid crystal molecules when rotated 360 ° along the helical structure of the liquid crystal molecules is used. .
[0035]
As a material used for the columnar structure 115, for example, a thermoplastic resin can be used. For this purpose, it is desired that the material be softened by heating and solidified by cooling without causing a chemical reaction with a liquid crystal material to be used and having appropriate elasticity.
[0036]
Specific examples include, for example, polyvinyl chloride resin, polyvinylidene chloride resin, polymethacrylate resin, polyacrylate resin, polyvinyl acetate resin, polystyrene resin, polyamide resin, polyethylene resin, polypropylene resin, fluorine resin, polyurethane Resins, polyacrylonitrile resins, polyvinyl ether resins, polyvinyl ketone resins, polyvinyl pyrrolidone resins, polycarbonate resins, chlorinated polyether resins, saturated polyester resins, and the like.
[0037]
These may be used singly or in combination, or the columnar structure 115 may be formed from a material containing at least one or a mixture of these.
[0038]
The substance is printed by a known printing method using a pattern so as to form dot columns as shown in FIG. Depending on the size of the liquid crystal display element and the pixel resolution, the size of the cross-sectional shape, the arrangement pitch, and the shape (such as a cylinder, a drum, or a polygonal pillar) are appropriately selected. It is more preferable that the columnar structure 115 is preferentially arranged between the electrodes 113 because the aperture ratio is improved.
[0039]
As the spacer 117, particles made of a hard material that is not deformed by heating or pressing are preferable. For example, finely divided glass fibers, inorganic materials such as ball-shaped silicate glass and alumina powder, or organic synthetic spherical particles such as divinylbenzene-based crosslinked polymers and polystyrene-based crosslinked polymers can be used.
[0040]
As described above, the hard spacer 117 that keeps the gap between the two substrates 112 at a predetermined size, and the thermoplastic high spacer that is arranged in the display area based on a predetermined arrangement rule and adhesively supports the pair of substrates 112. By providing the resin structure 115 containing a molecular material as a main component, both the substrates 112 are firmly supported over the entire area of the substrate 112, and there is no arrangement unevenness, and the generation of bubbles in a low-temperature environment can be suppressed. it can.
[0041]
(Example of manufacturing liquid crystal display element)
Here, a manufacturing example of the liquid crystal display element 100 will be briefly described. First, a plurality of strip-shaped transparent electrodes are formed on two transparent substrates, respectively. The transparent electrode is formed by forming an ITO film on a substrate by a sputtering method or the like and then performing patterning by a photolithography method.
[0042]
Next, a transparent insulating film and an orientation control film are formed on the transparent electrode forming surface of each substrate. The insulating film and the orientation control film can each be formed by a known method such as a sputtering method, a spin coating method, or a roll coating method using an inorganic material such as silicon oxide or an organic material such as a polyimide resin.
[0043]
Note that the rubbing treatment is not usually performed on the orientation control film. Although the function of the alignment control film is not yet clear, it is considered that the presence of the alignment control film can give a certain degree of anchoring effect to the liquid crystal molecules, and the characteristics of the liquid crystal display element change with time. Can be prevented. In addition, a function as a color filter may be provided by adding a dye to these thin films to improve color purity and contrast.
[0044]
Thus, a resin structure is formed on the electrode forming surface of one of the substrates provided with the transparent electrode, the insulating film, and the alignment control film. The resin structure is a printing method in which a paste-like resin material obtained by dissolving a resin in a solvent is extruded with a squeegee through a screen plate or a metal mask and printed on a substrate mounted on a flat plate, a dispenser method or an ink jet method. For example, it can be formed by a method of discharging a resin material onto a substrate from the tip of a nozzle to form the resin material, or a method of supplying the resin material onto a flat plate or a roller and then transferring the resin material to the substrate surface. . It is desirable that the height at the time of forming the resin structure be larger than the desired thickness of the liquid crystal display layer.
[0045]
A sealing material is provided on the electrode forming surface of the other substrate using an ultraviolet curable resin, a thermosetting resin, or the like. The sealant is arranged in a continuous ring at the outer edge of the substrate. The arrangement of the sealing material, like the resin structure described above, a method of forming a resin by discharging a resin from the tip of a nozzle onto a substrate, such as a dispenser method or an inkjet method, a screen plate, a printing method using a metal mask, or the like, After the resin is formed on a flat plate or a roller, it may be transferred by a transfer method of transferring the resin onto a transparent substrate. Further, spacers are sprayed on the surface of at least one of the substrates by a conventionally known method.
[0046]
Then, the pair of substrates are overlapped so that the electrode forming surfaces face each other, and heated while being pressed from both sides of the pair of substrates. Pressing and heating are performed, for example, as shown in FIG. -It can be performed by passing between the roller 151 and the flat plate 150 while applying pressure. By using such a method, a cell can be manufactured with high accuracy even using a flexible substrate having flexibility such as a film substrate. When the resin structure is formed from a thermoplastic polymer material, the resin structure is softened by heating and solidified by cooling, and the two substrates can be bonded by the resin structure. When a thermosetting resin material is used as the sealing material, the sealing material may be cured by heating when the substrates are superposed.
[0047]
In this overlapping step, a liquid crystal material is dropped on one of the substrates, and the liquid crystal material is injected into the liquid crystal element simultaneously with the overlapping of the substrates. In this case, a spacer may be included in the liquid crystal material in advance, and the spacer may be dropped on at least one of the substrates on which the strip-shaped electrode is formed.
[0048]
By dropping the liquid crystal material on the edge of the substrate and spreading the liquid crystal material to the other end while overlapping the substrates with a roller, the entire substrate can be filled with the liquid crystal material. By doing so, it is possible to reduce entrapment of bubbles generated when the substrates are overlapped with each other in the liquid crystal material.
[0049]
Thereafter, the pressing of the substrate is continued until the substrate temperature is reduced to at least the softening temperature of the resin material constituting the resin structure, and then the pressing is stopped, and further, when a photocurable resin material is used as the sealing material, Thereafter, light irradiation is performed to cure the sealing material.
[0050]
In the same procedure, the liquid crystal material is changed to a material having a different selective reflection wavelength, and cells for blue display, green display, and red display are manufactured. The cells thus manufactured are stacked in three layers, these are attached with an adhesive, and a light absorbing layer is further provided as a lowermost layer to obtain a full-color liquid crystal display device.
[0051]
(Power / control circuit, see FIGS. 8 to 10)
Next, a power supply circuit and a control circuit of the liquid crystal display device 10 will be described with reference to FIGS.
[0052]
The power supply circuit includes a power supply 135 such as a battery and a distributor 136. The power distributor 136 supplies power to the central processing unit (CPU) 51, the LCD controller 55, another control circuit 141, the input / output device 142, and the booster circuit 137. The central processing unit 51 exchanges signals with the LCD controller 55, another control circuit 141, and the input / output device 142. The booster circuit 137 supplies power of a predetermined specification to the drive IC 59 (131, 132, see FIG. 10). The LCD controller 55 operates the drive IC 59 in cooperation with the central processing unit 51 to drive and control the liquid crystal display element 100.
[0053]
The central processing unit 51 starts operating when the power switch is turned on. The booster circuit 137 can be turned on / off by a command from the central processing unit 51.
[0054]
On the other hand, the control circuit includes a central processing unit 51, an image memory 52 for temporarily storing image data, and an image processing device for performing necessary image processing on image data transmitted from an external device such as the personal computer 1 via the interface 53. 54. The central processing unit 51 includes a ROM 57 storing various control programs and a RAM 58 temporarily storing various information. The central processing unit 51 receives signals from the operation keys 22, the power switch 23, and the attachment confirmation sensor 46.
[0055]
The image data transmitted through the interface 53 is temporarily stored in the image memory 52 via the image processing device 54. The LCD controller 55 controls the driving IC 59 based on the data stored in the image memory 52, sequentially applies a voltage between each scanning electrode and the signal electrode of the liquid crystal display element 100, and writes an image on the liquid crystal display element 100. As described above, the liquid crystal display element 100 can maintain the display state even when taken out of the frame 40. Further, after taking out, another display element 100 can be mounted and writing of an image can be continued.
[0056]
As shown in FIG. 10, the pixel configuration of the liquid crystal display element 100 is represented by a matrix of a plurality of scanning electrodes R1, R2 to Rm and signal electrodes C1, C2 to Cn (n and m are natural numbers). The scan electrodes R1, R2 to Rm are connected to output terminals of the scan drive IC 131, and the signal electrodes C1, C2 to Cn are connected to output terminals of the signal drive IC 132.
[0057]
The scan driving IC 131 outputs a selection signal to a predetermined one of the scanning electrodes R1, R2 to Rm to make it in a selected state, and outputs a non-selection signal to other electrodes to make it in a non-selected state. The scan driving IC 131 sequentially applies a selection signal to each of the scan electrodes R1, R2 to Rm while switching the electrodes at predetermined time intervals. On the other hand, the signal driving IC 132 simultaneously outputs a signal corresponding to image data to each of the signal electrodes C1, C2 to Cn in order to rewrite each pixel on the selected scanning electrode R1, R2 to Rm. For example, when the scanning electrode Ra is selected (a is a natural number satisfying a ≦ m), the pixels LRa-C1 to LRa-Cn at the intersections of the scanning electrode Ra and the signal electrodes C1, C2 to Cn are simultaneously rewritten. Can be As a result, the voltage difference between the scanning electrode and the signal electrode in each pixel becomes the pixel rewrite voltage, and each pixel is rewritten according to this rewrite voltage.
[0058]
Here, assuming that the first threshold voltage for untwisting the liquid crystal exhibiting the cholesteric phase is Vth1, after applying the voltage Vth1 for a sufficient time, the voltage is changed to the second threshold voltage Vth2 smaller than the first threshold voltage Vth1. If it is lowered below, it will be in the planar state. Further, when a voltage of Vth2 or more and Vth1 or less is applied for a sufficient time, a focal conic state is established. These two states are stably maintained even after the voltage application is stopped. By applying a voltage between Vth1 and Vth2, halftone display, that is, gradation display is possible.
[0059]
Rewriting of each pixel can be performed by the above-described method. However, when an image is already displayed, it is preferable to reset all the pixels to the same display state before rewriting in order to eliminate the influence of the image. The reset may be performed for all pixels at once or for each scan electrode. For example, it has been found that a relatively long time is required to reset each pixel to the focal conic state in order to obtain a sufficiently transparent state. Therefore, it is preferable to collectively reset all the pixels to the focal conic state prior to rewriting because the rewriting time can be shortened as compared with the case where resetting is performed for each scanning electrode.
[0060]
(Other liquid crystal display elements)
In the liquid crystal display element 100, the element configuration in which the resin columnar structure is included in the liquid crystal display layer has been described. With such a configuration, a liquid crystal display element having lightness and excellent display characteristics can be manufactured using a film substrate, and various excellent features such as easy upsizing, relatively low driving voltage, and strong impact can be obtained. It has features and is particularly useful. However, the memory-like liquid crystal itself is not necessarily limited to this configuration, and the liquid crystal is dispersed in the conventionally known polymer three-dimensional network structure, or the polymer three-dimensional network structure is present in the liquid crystal. The liquid crystal display layer may be formed as a so-called polymer-dispersed liquid crystal composite film.
[0061]
(Refer to the control procedure, FIGS. 11 to 13)
Hereinafter, a control procedure performed by the central processing unit 51 in the display device 10 will be described with respect to a portion related to the present invention.
[0062]
FIG. 11 shows a main routine of the central processing unit 51. Here, the central processing unit 51 starts up based on the turning on of the power switch 23, and initializes the RAM 58, registers, and the like in step S1. In addition, the power supply to each unit connected to the central processing unit 51 except the booster circuit 137 is started.
[0063]
Next, in step S2, after confirming that the liquid crystal display element 100 is mounted on the basis of the signal from the sensor 46, in step S3, the liquid crystal display constituted by the LCD controller 55 and the driving IC 59 (131, 132). The drive of the element 100 is activated. Specifically, the booster circuit 137 connected to the drive IC 59 is turned on, so that writing to the liquid crystal display element 100 is enabled. Also, the timer for power saving is started.
[0064]
Next, the subroutines of steps S4 and S5 are sequentially called to execute necessary processing. That is, in step S4, the screen is updated, and in step S5, the drive IC 59 of the liquid crystal display element 100 is deactivated at a predetermined timing. That is, power saving processing for turning off the booster circuit 137 connected to the driving IC 59 is performed. Note that these subroutines will be described later.
[0065]
Next, in step S6, it is determined whether or not there is a termination command (such as turning off the power switch 23) from the user. If there is no termination command, the process returns to step S4. If there is no termination command, each unit connected to the central processing unit 51 in step S7. Then, the power supply to the central processing unit 51 itself is stopped.
[0066]
As described above, in the first embodiment, the power switch 23 is provided, and when the display does not need to be rewritten, the operations of the central processing unit 51 and the like are completely stopped to reduce the standby power to zero. A display device with high power saving can be provided.
[0067]
FIG. 12 shows a subroutine of the screen updating process executed in step S4. Here, first, it is determined whether or not the reset key (one of the keys 22 shown in FIG. 1) for erasing the screen has been turned on in step S11. If it has been turned on, it is determined in step S12 whether or not the booster circuit 137 is on. If it is on, the screen is reset in step S15. On the other hand, if it is off, the step-up circuit 137 is turned on in step S13, the power saving timer is started in step S14, and the screen is reset in step S15. The reset is performed by, for example, writing in the liquid crystal display element 100 so as to fill the screen with black, white, or another single color. As a result, it is possible to delete an image that is no longer required to be displayed or to delete an image that is not displayed and is not to be seen by others.
[0068]
If there is no reset request (NO in step S11), it is determined in step S16 whether a data transmission request has been received from an external device (personal computer 1). The data transmission request is, for example, when the external terminal is operated to display a predetermined image stored in the external terminal such as a calendar or a schedule table on the sub-display, or on a window displayed on the main screen of the external terminal. When another window is newly opened or the window is closed, a window to be deleted from the main screen is transmitted from the external terminal to be displayed on the sub-display.
[0069]
If the data transmission request is received, it is determined in a step S17 whether or not the booster circuit 137 is on. If it is on, the screen is rewritten to the received image in step S20. On the other hand, if it is off, the step-up circuit 137 is turned on in step S18, the power saving timer is started in step S19, and the received image is rewritten in step S20.
[0070]
FIG. 13 shows a subroutine of the power saving process executed in step S5. First, in step S21, it is determined whether or not the booster circuit 137 is in the off state. If the booster circuit 137 is in the off state, this subroutine is immediately terminated. If the power-on timer is on, the CPU waits for the power-saving timer to count up in step S22, turns off the power of the booster circuit 137 in step S23, and resets the power-saving timer in step S24. After the screen is rewritten in this way, the booster circuit 137 that consumes a large amount of power is stopped after waiting for the counting of a predetermined time by the timer, and the display is continued, whereby power saving can be achieved. In addition, since the booster circuit 137 is turned off after a predetermined time (for example, five minutes) has elapsed since the writing of the image, the display device is in a standby state until the predetermined time has elapsed. Can be written. Therefore, the operability when writing an image continuously in a short time is excellent.
[0071]
(Display element after image writing)
The liquid crystal display element 100 on which an image has been written as described above can be removed from the frame 40 and a new liquid crystal display element 100 can be mounted to write the next image. By repeating mounting, writing, and removing in this manner, a plurality of images can be obtained using one display device 10. The display element 100 from which the image has been written and removed may be arranged side by side on a support base such as an easel. If one large image is divided and written on the plurality of display elements 100 and arranged, a large image can be displayed.
[0072]
When removing the liquid crystal display element 100 from the frame 40, additional information may be written into the element 100. For example, if one large image is to be written by dividing into a plurality of liquid crystal display elements 100, the display position or the communication relationship of the images may be written to each element 100 to the extent that the display image is not damaged.
[0073]
Alternatively, by displaying the writing date and time of the image, the time when the element 100 has been removed from the frame 40 can be grasped. When the removed time is longer than the predetermined time, the image information may be re-input to the display device 10 by the operability of a specific key, and the image may be rewritten. In this case, the driving method may be changed by increasing the driving voltage for the liquid crystal display element 100 or setting the voltage application time longer. Also, at the time of this re-input, the screen may be reset and then written. Alternatively, a means for detecting the temperature of the liquid crystal display element 100 and a means for changing the driving method (driving voltage, application time, etc.) according to the detected temperature may be provided.
[0074]
Furthermore, in order to keep the confidentiality of the display image in consideration of the case where the operator temporarily leaves the front of the display device 10 or the like, a means for temporarily making the display screen invisible, for example, a wallpaper display means is provided in the control circuit. It may be built-in.
[0075]
(Second embodiment, see FIGS. 14 to 17)
FIG. 14 shows an external appearance of an information display terminal device (electronic book device) 200 in which the liquid crystal display device according to the present invention is integrated into a housing 201, and FIG. 15 shows a control circuit thereof. The electronic book device 200 includes liquid crystal display elements 202 and 203 each having a touch panel on the right and left sides of a case 201 that can be opened, a plurality of operation keys 204 for instructing display switching and page turning, and an external device. And an IrDA terminal 205 for exchanging information with a LAN card, a LAN card slot 206 for connecting to a LAN network, and a memory card (ATA memory card, smart media, etc.) slot 207 for storing image data and the like. ing. The housing 201 can be folded using the support shaft 208 at the center as a fulcrum.
[0076]
The liquid crystal display elements 202 and 203 exhibit the same cholesteric phase as that described in the first embodiment except that a touch panel is provided on the surface.
[0077]
The electronic book device 200 is controlled by the main CPU 70, and information is input from the IrDA terminal 205, the LAN card 72, and the memory card 73 via the I / O controller 74. The liquid crystal display elements 202 and 203 are controlled by the sub CPU 80 and include a plurality of operation keys 204, a DC / DC converter 82 as a power supply, and touch panels 83 and 84. The CPUs 70 and 80 include a RAM 91 and a flash memory 92, and issue instructions to an LCD controller 93 to drive the liquid crystal display elements 202 and 203.
[0078]
The main CPU 70 operates using the battery 71 as a power supply. The main CPU 70 has a wake-up mode and a sleep mode. When writing an image, the main CPU 70 enters the wake-up mode, and enters the sleep mode when the image writing is completed. In the sleep mode, power consumption is suppressed by stopping clock oscillation or stopping supply of a clock to internal circuits such as a memory, a register, and a counter. When the main CPU 70 is in the sleep mode, the mode shifts to the wake-up mode when an interrupt signal is received from the sub CPU 80.
[0079]
The sub CPU 80 also uses the battery 81 as a power source. The sub CPU 80 is always in the operating state, and can detect the input from the touch panels 83 and 84 and the operation keys 204 even when the DC / DC converter 82 is off. It is preferable that the sub CPU 80 has a low processing speed, a low degree of integration, and low power consumption.
[0080]
In such a control circuit, as shown in FIG. 16, the sub CPU 80 determines whether there is an input on the touch panels 83 and 84 in step S51 and whether there is an input on the operation key 204 in step S52. Wait until there is any input. If there is any input, the DC / DC converter 82 is turned on in a step S53, an interrupt signal is given to the main CPU 70 in a step S54 to start the main CPU 70, and data is transmitted to the main CPU 70 in a step S55.
[0081]
On the other hand, as shown in FIG. 17, the main CPU 70 receives the data from the sub CPU 80 in step S61, executes the interpretation / processing of the data in step S62, and executes the liquid crystal display elements 202 and 203 based on the data in step S63. To display. Next, when the completion of the display update is confirmed in step S64, the end of the operation is notified to the sub CPU 80 in step S65, and the sleep state is set in step S66.
[0082]
When it is determined in step S64 that the update has not been completed, for example, when a continuous key operation such as continuously pressing a predetermined operation key for the purpose of continuous page feed is performed, The process returns to S62 and S63 and updates the display again.
[0083]
Next, the sub CPU 80 confirms that the operation end is notified from the main CPU 70 in step S56, and turns off the DC / DC converter 82 in step S57. The DC / DC converter 82 may turn on only a predetermined device. For example, only the operated liquid crystal display element 202 or 203 may be driven.
[0084]
Further, in the second embodiment, immediately after writing the image, the circuits other than the circuit parts necessary for the key input and the pen-down detection to the touch panel are turned off, and the power is supplied only to the circuits with very low power consumption. With such control, power saving can be effectively achieved. Therefore, in a portable electronic device using a battery or the like as a power source as in the second embodiment, it is effective for power saving.
[0085]
Further, the written image is retained even in such a power saving state, and if it is necessary to rewrite the screen, the main CPU 70 can immediately shift to the wake-up mode and execute the image rewriting by key input and pen down. Therefore, operability is not impaired for power saving. In particular, in the case of a continuous page feed operation, the driving circuit is continuously kept on, so that the operation is not hindered. In the case of a single operation, the driving circuit is immediately turned off, thereby saving power. The effect is kept high.
[0086]
Although the power switch is not provided in the second embodiment, when the operator needs to open the electronic book device 200, the display contents can be immediately checked, and when rewriting is necessary, the key operation or pen down operation is performed. If rewriting is instructed, the screen can be rewritten. Therefore, there is no problem that the battery is consumed by forgetting to turn off the power switch, and the display screen disappears due to the operation of the auto power off mechanism.
[0087]
Further, the sub CPU 80, which is always woken up, is monitored for a signal that triggers the wake-up of the main CPU 70. Therefore, the main CPU 70 has one input terminal for interruption for waking up from the sleep state. It only needs one.
[0088]
In the second embodiment, the sub CPU 80 always operates, but a sub CPU having a sleep mode may be used to further reduce power consumption. When a sub CPU having a sleep mode is used, an interrupt signal may be given to the sub CPU by pen-down on the touch panel or operation of an operation key to return to the normal mode.
[0089]
In a portable electronic device such as the electronic book device 200 of the second embodiment, the use of a reflective liquid crystal display element is advantageous for outdoor use. That is, it is possible to perform a display that is easy to view without a decrease in contrast under external light, and a backlight for display is unnecessary. From such a viewpoint, the second embodiment is applicable not only to the electronic book device but also to various portable electronic devices. That is, the present invention is also effective for portable electronic devices such as a portable telephone, a PDA, and a portable audio device (for example, a portable MD player and a portable CD player) for displaying contents of a storage medium.
[0090]
(Third embodiment, see FIGS. 18 to 20)
FIG. 18 shows the appearance of an information display terminal device (mobile phone) 300 according to the third embodiment of the present invention. The mobile phone 300 is also capable of transmitting and receiving e-mail, and includes a liquid crystal display element 301 for displaying various information, an operation panel 302 for a user to make various inputs, a speaker 303 for communication, a microphone 304 and An antenna 305 and the like are provided.
[0091]
The liquid crystal display element 301 has the same cholesteric phase as that described in the first embodiment except that a touch panel is provided on the surface. On the liquid crystal display element 301, various information such as a telephone number of the other party to be transmitted, an e-mail address, an electronic document, an image, a transmission / reception date and time, a mark indicating a radio wave reception status, and a battery state are displayed.
[0092]
FIG. 19 shows a control circuit of the mobile phone 300. This control circuit is mainly configured by a CPU 310 that has a built-in function of an LCD controller and performs overall control. The CPU 310 includes a ROM 311, a RAM 312, and a power supply 313. The liquid crystal display element 301, the operation panel 302, the illumination 315, the image memory 316, the image processing circuit 317, and the DC / DC converter 318 as a power supply are connected to the CPU 310.
[0093]
Further, a speaker 303 and a microphone 304 are connected to the CPU 310 via an audio processing circuit 321, and an antenna 305 is connected via a wireless transmission / reception circuit 322.
[0094]
As shown in FIG. 18, when there is an incoming call or mail, the CPU 310 temporarily drives the liquid crystal display element 301 to receive incoming information (for example, incoming date and time, type of telephone or mail, number of incoming calls, source information). , Title, size, etc.) are displayed and stored.
[0095]
FIG. 20 shows a control procedure performed by the CPU 310. The CPU 310 wakes up based on an interrupt signal due to a key operation on the operation panel 302 or an incoming call. When the CPU 310 wakes up, it resets and starts a timer for shifting the CPU 310 to the sleep state in step S71.
[0096]
In the case of waking up by a key operation (YES in step S72), the DC / DC converter 318 is turned on in step S73, and the display is updated in accordance with the key input in step S74. The ON state of the DC / DC converter 318 is maintained until the end of the key input is determined in step S75, and the DC / DC converter 318 is turned off in step S76 when the end of the key input is determined. As a result, the key input of the other party's telephone number, mail address, document, and the like can be smoothly performed.
[0097]
Next, when it is confirmed in step S77 that a transmission command has been input, transmission / call is processed in step S78. When the transmission / call is completed (YES in step S79), a sleep state is set. If there is no transmission command and the count-up of the sleep timer is confirmed in step S80, the contents of the input are deleted in step S81, and the sleep state is set.
[0098]
Until the sleep timer counts up (NO in step S80), key input is waited in step S82, and if there is a key input, the sleep timer is reset and started in step S83.
[0099]
On the other hand, if CPU 310 wakes up due to an incoming call (YES in step S84), it receives data in step S85, and when it is confirmed in step S86 that the reception has been completed, turns on DC / DC converter 318 in step S87. Then, in step S88, the incoming call is displayed on the liquid crystal display element 301, and in step S89, the DC / DC converter 318 is turned off to enter the sleep state.
[0100]
As described above, the incoming information displayed on the liquid crystal display element 301 is retained by the memory properties of the liquid crystal even if the driving unit of the liquid crystal display element 301 is turned off after the display, and does not cause any trouble. Further, the display can be viewed without a backlight, which is suitable for energy saving. Moreover, it is possible to make the user understand that there is an incoming call with the minimum power.
[0101]
The third embodiment is applicable not only to a mobile phone but also to various information electronic devices. For example, the present invention can be applied to display of incoming information in a mobile device for mail, a pager, a facsimile, and the like. Further, the present invention can be applied to the display of program information in a radio receiver, a television receiver, a VTR, and the like.
[0102]
(Fourth embodiment, see FIGS. 21 to 23)
FIG. 21 shows an online display terminal device 400 according to a fourth embodiment of the present invention. In the display terminal device 400, a plurality of devices 400 are connected to one host device 420 by a connection line 425 (dedicated cable, telephone line, or wireless), and function as an online advertising board. Each display terminal device 400 includes a liquid crystal display element 401 on the front, and displays the advertisement information stored in the built-in nonvolatile memory or the advertisement information transmitted from the host device 420 on the liquid crystal display element 401. The turning on and off of the display terminal device 400, the order of the advertisement information to be displayed, and the like are based on an instruction from the host device 420. Therefore, the display terminal device 400 includes a power supply but does not include a power switch.
[0103]
As the liquid crystal display element 401, an element exhibiting the same cholesteric phase as described in the first embodiment is used.
[0104]
FIG. 22 shows a control circuit of the display terminal device 400. This control circuit is mainly configured by a CPU 430 that incorporates a ROM 431 and a RAM 432 and performs overall control. The drive IC 435 of the liquid crystal display element 401 is connected to the CPU 430 via the LCD controller 434, and further, a DC / DC converter 436 as a power supply, an image processing circuit 437, and an image memory 438 are connected. A signal from the host device 420 is input to the CPU 430 and the image processing circuit 437 via the interface 439.
[0105]
FIG. 23 shows a control procedure performed by the CPU 430. The CPU 430 wakes up based on the interrupt signal from the host device 420, and processes the reception of data from the host device 420 in step S101. When the end of reception is confirmed in step S102, the DC / DC converter 436 is turned on in step S103. Then, in step S104, the display of the liquid crystal display element 401 is updated, and in step S105, the DC / DC converter 436 is turned off, and the apparatus enters a sleep state.
[0106]
The fourth embodiment is not limited to the use as an advertising board, but can be applied to various online display terminals. For example, it can be used as an information board, a bulletin board, a timetable, a price tag, an electronic newspaper, a score board, a conference material display board, and the like.
[0107]
(Fifth embodiment, see FIGS. 24 to 26)
FIG. 24 shows an electronic photo frame 500 according to a fifth embodiment of the present invention. In the electronic photo frame 500, a memory card 510 can be attached to and detached from a slot 502, and image data stored in the memory card 510 is read and displayed on a liquid crystal display element 501. As the liquid crystal display element 501, a liquid crystal display element having the same cholesteric phase as that described in the first embodiment is used.
[0108]
When the memory card 510 is inserted into the slot 502, the image of the first page is displayed, and the image is updated by operating the page feed key 503 and the page return key 504 at the bottom. Further, a built-in timer may be used to sequentially update images at regular intervals.
[0109]
FIG. 25 shows a control circuit of the electronic photo frame 500. This control circuit is mainly configured by a CPU 530 that incorporates a ROM 531 and a RAM 532 and performs overall control. A driving IC 535 of the liquid crystal display element 501 is connected to the CPU 530 via an LCD controller 534. Further, the CPU 530 includes keys 503, 504, a DC / DC converter 536 as a power supply unit, and an image processing circuit 537 including an image memory 538. It is connected. Data from the memory card 510 is input to the CPU 530 and the image processing circuit 537 via the I / O controller 539.
[0110]
FIG. 26 shows a control procedure performed by the CPU 530. The CPU 530 wakes up based on the loading signal of the memory card 510 or the operation signal of the keys 503 and 504, and reads data from the memory card 510 in step S111. When the end of the reading is confirmed in step S112, the DC / DC converter 536 is turned on in step S113. Then, in step S114, the display of the liquid crystal display element 501 is updated, and in step S115, the DC / DC converter 536 is turned off, and the apparatus enters a sleep state.
[0111]
The electronic photo frame 500 according to the fifth embodiment is used in a stand-alone manner, has no communication means, and has an advantage that power is not consumed by communication.
[0112]
The fifth embodiment is applicable to a display device of a vending machine, a menu display device in a restaurant, a clock, a timer, and the like, in addition to the electronic photo frame.
[0113]
(Other embodiments)
Note that the liquid crystal display device and the display system according to the present invention are not limited to the above embodiment, and can be variously modified within the scope of the gist.
[0114]
In particular, the appearance of the liquid crystal display device and the configuration of the attachment / detachment mechanism of the display element are arbitrary. As for the liquid crystal, various cell configurations and driving methods can be adopted.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a liquid crystal display device according to a first embodiment of the present invention, showing a case where a display is placed vertically.
FIG. 2 is a perspective view showing the liquid crystal display device, showing a case where a display is placed horizontally.
FIG. 3 is a perspective view showing a state where a liquid crystal display element is taken out of the liquid crystal display device.
FIG. 4 is a sectional view of the liquid crystal display device.
FIG. 5 is a cross-sectional view illustrating an example of a liquid crystal display element used as a display.
FIG. 6 is a plan view showing a state in which a columnar structure and a sealing material are formed on a film substrate of the liquid crystal display element.
FIG. 7 is an explanatory view showing a manufacturing process of the liquid crystal display element.
FIG. 8 is a block diagram showing a power supply circuit of the liquid crystal display device.
FIG. 9 is a block diagram showing a control circuit of the liquid crystal display device.
FIG. 10 is a block diagram showing a matrix drive circuit of the liquid crystal display element.
FIG. 11 is a flowchart showing a main routine of a control procedure.
FIG. 12 is a flowchart showing a subroutine for screen updating.
FIG. 13 is a flowchart illustrating a subroutine of a power saving process.
FIG. 14 is an exemplary perspective view showing an electronic book device according to a second embodiment of the invention.
FIG. 15 is a block diagram showing a control circuit of the electronic book device.
FIG. 16 is a flowchart showing a control procedure of a sub CPU in the electronic book device.
FIG. 17 is an exemplary flowchart showing the control procedure of a main CPU in the electronic book device.
FIG. 18 is a front view showing a mobile phone according to a third embodiment of the present invention.
FIG. 19 is a block diagram showing a control circuit of the mobile phone.
FIG. 20 is a flowchart showing a control procedure of a CPU in the mobile phone.
FIG. 21 is a perspective view showing an online display terminal device according to a fourth embodiment of the present invention.
FIG. 22 is a block diagram showing a control circuit of the online display terminal device.
FIG. 23 is a flowchart showing a control procedure of a CPU in the online display terminal device.
FIG. 24 is a perspective view showing an electronic photo frame according to a fifth embodiment of the present invention.
FIG. 25 is a block diagram showing a control circuit of the electronic photo frame.
FIG. 26 is a flowchart showing a control procedure of a CPU in the electronic photo frame.
[Explanation of symbols]
10. Liquid crystal display device
51 Central processing unit
55… LCD controller
59 (131, 132) ... Drive IC
70: Main CPU
80 ... Sub CPU
82 DC / DC converter
93 ... LCD controller
100 ... Liquid crystal display element
137 ... Booster circuit
202, 203: Liquid crystal display element
300… Mobile phone
301 ... Liquid crystal display element
310 ... CPU
318 DC / DC converter
400 ... On-line display terminal device
401 ... Liquid crystal display element
430 ... CPU
434 ... LCD controller
436 DC / DC converter
500 ... Electronic photo frame
501: Liquid crystal display element
510… Memory card
530 ... CPU
534 ... LCD controller
536 ... DC / DC converter

Claims (10)

A liquid crystal display element comprising a display screen using a reflective liquid crystal having memory properties,
A driving circuit for writing an image to the liquid crystal display element,
A data processing device connected to the drive circuit;
A power supply circuit for supplying power to the drive circuit and the data processing device,
After writing an image on the liquid crystal display element, at least a part of the power supply circuit and / or an internal circuit of at least a part of the data processing device is disabled, and a part of the power supply circuit and / or Control means for maintaining the image in a visible state by utilizing the memory properties and reflection characteristics of the liquid crystal display element even after disabling the internal circuit of the data processing device;
A liquid crystal display device comprising: 2. The liquid crystal display according to claim 1, wherein the liquid crystal display element comprises a display screen using liquid crystal obtained by adding a chiral dopant in a nematic liquid crystal to a cholesteric phase at room temperature. apparatus. 3. The liquid crystal display device according to claim 1, wherein a halftone display is performed by sandwiching a liquid crystal layer between a plurality of scanning electrodes and a plurality of signal electrodes and performing matrix driving. The liquid crystal display device according to the above. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal display element is capable of full-color display. 5. The liquid crystal according to claim 1, wherein the liquid crystal display element is formed by laminating a plurality of display layers including a reflective liquid crystal having a memory property. Display device. 6. The liquid crystal display device according to claim 1, wherein the liquid crystal display element has an alignment control film provided on a substrate that sandwiches liquid crystal. The liquid crystal display device according to claim 7, wherein the alignment control film is not subjected to a rubbing process. 2. The liquid crystal display device according to claim 1, further comprising a reset key for instructing that the display screen of the liquid crystal display element be written so as to be filled with a single color and reset the screen. A plurality of liquid crystal display devices according to claim 1,
A host device to which the plurality of liquid crystal display elements are connected;
A display system comprising: A liquid crystal display element,
A driving circuit for the liquid crystal display element,
A data processing device connected to the drive circuit;
A receiving circuit for receiving an external signal,
A slot for detachably holding a storage medium for storing image information to be displayed on the liquid crystal display element,
Control means for disabling at least a part of the internal circuit of the data processing device while maintaining the display of the liquid crystal display element so as to be visible; and
An openable and closable housing for accommodating the respective members and means,
The liquid crystal display element is invisible when the casing is closed,
A liquid crystal display device characterized by the above-mentioned.

Images