JP3726824B2 - Liquid crystal display device and display system - Google Patents

Description

[0001]
BACKGROUND 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 memory properties, and a display system including the liquid crystal display device.
[0002]
BACKGROUND AND PROBLEMS OF THE INVENTION
In recent years, display devices having a display screen using liquid crystal have been widely used. Various types of liquid crystal display elements are provided, and as a display element having a memory property, a reflection type element using a ferroelectric liquid crystal or a liquid crystal exhibiting a cholesteric phase is known. A commonly used liquid crystal display element such as a TN type performs so-called refresh driving in which image writing is repeated in a very short time period to maintain display. On the other hand, the memory-type liquid crystal display element is excellent in terms of power saving because the written image is retained even after the application of the driving voltage is stopped.
[0003]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid crystal display device and a display system using a reflective liquid crystal that has a memory property that allows visible display at all times and good visibility even outdoors, so as to further save power. Is to provide.
[0004]
Another object of the present invention is to provide a liquid crystal display device that can display contents corresponding to various data sources and can easily maintain confidentiality of display.
[0005]
Configuration, operation and effect of the invention
In order to achieve the above object, the liquid crystal display device according to the first invention uses at least one liquid crystal that exhibits a cholesteric phase at room temperature and uses an alignment control film that is not subjected to rubbing. A reflective liquid crystal display element composed of a display layer, a drive circuit for writing an image so that one display layer is displayed in a planar state, a focal conic state, and a halftone display state for each pixel, and connected to the drive circuit A data processing device, a power supply circuit for supplying power to the drive circuit and the data processing device, A power switch for turning on and off the main power supply and an instruction to reset the screen by writing to fill the display screen of the liquid crystal display element with a single color provided independently of the power switch. A reset key for 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 are inactivated, and a part of the power supply circuit or / and And a control means for maintaining the image in a visually recognizable state using the memory property and the reflection characteristic of the liquid crystal display element even after the internal circuit of the data processing device is inactivated.
[0006]
Since the reflective liquid crystal having memory characteristics used in the liquid crystal display device according to the first aspect of the invention retains the image even after the power supply is stopped after the screen is rewritten, After writing, at least a part of the power supply circuit and / or an internal circuit of at least a part of the data processing device are deactivated. Further, even after a part of the power supply circuit and / or the internal circuit of the data processing device is inactivated, the image is maintained in a visually recognizable state using the memory property and the reflection characteristic of the liquid crystal display element. As a result, it is possible to visually recognize the display at all times, and it is possible to suppress power consumption during standby, and to further increase the power saving effect. In addition, since a reflective liquid crystal that performs display by external light incident on the screen is used, a backlight is unnecessary, and the power saving effect is extremely high, and good visibility is maintained even outdoors.
[0007]
In the liquid crystal display device according to the first aspect of the invention, the liquid crystal display element may be a display screen configured by using a liquid crystal in which a sufficient amount of chiral dopant is added to nematic liquid crystal to exhibit a cholesteric phase at room temperature. Good. By controlling the mixing 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, the liquid crystal display element is preferably 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 matrix driving is performed. The display power is improved.
[0009]
Further, the liquid crystal display element is preferably capable of full color display. If full-color display is used, display with good image recognition becomes possible.
[0010]
Furthermore, the liquid crystal display element may be formed by laminating a plurality of display layers including a reflective liquid crystal having memory properties. Bright display is possible, and full-color display can be supported.
[0011]
Furthermore, the liquid crystal display element is Do not rub Having an orientation control film And Can prevent changes in display characteristics over time With The viewing angle dependency is reduced and the visibility is improved.
[0012]
The liquid crystal display device according to the first aspect of the present invention further includes a reset key for instructing to reset the screen by writing so as to fill the display screen of the liquid crystal display element with a single color. Have . The screen can be reset when needed by the user to maintain confidentiality and prevent screen burn-in.
[0013]
A display system according to a second invention includes a plurality of the liquid crystal display devices and the plurality of liquid crystal displays. apparatus And a host device connected thereto. A display system having the various effects described above can be constructed.
[0016]
DETAILED DESCRIPTION OF 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 the 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 body 40, and a full-color liquid crystal display element 100.
[0018]
The display device 10 displays fixed information that does not need to be frequently rewritten, such as a schedule table, calendar, telephone directory, address book, memo, map, incoming e-mail information, and the like. By displaying these fixed information on the device 10 as a sub display, it is possible to efficiently use the entire area of the display of the personal computer 1 and efficiently perform editing and the like. The display device 10 may display an inactive window hidden under another window when displaying a multi-window, or may display a window closed last. An image for viewing may be displayed. In any case, since the display device 10 can perform color display as described later, it is possible to perform colorful and highly visible display.
[0019]
The frame body 40 is formed with an attachment / detachment opening 41 for attaching / detaching the liquid crystal display element 100, and is attached to the support arm 30 via the 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 degrees and used in a horizontally long state. The rotation may be performed by the user turning the frame body 40 by hand, or the rotation shaft 31 may be automatically switched by providing a driving mechanism including a motor.
[0020]
FIG. 3 shows a state in which the liquid crystal display element 100 is taken out from the frame body 40, and FIG. Specifically, the frame body 40 includes a rear fixed frame 42 and a front frame 43, and the front frame 43 is fastened / fixed to the rear fixed frame 42 by a fixture 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 mounting state is detected by the sensor 46. Further, as will be described in detail below, the liquid crystal display element 100 has scanning electrodes and signal electrodes arranged in a matrix, and these electrodes are mounted with the scanning driving IC terminal portion 133 and the signal driving IC terminal portion 134 when mounted. Is electrically connected.
[0021]
On the other hand, the liquid crystal display element 100 is 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, the extracted liquid crystal display element 100 exposes the end of the electrode 114 on the front and the end of the electrode 113 (not shown in FIG. 3) 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, the liquid crystal display element 100 can be taken out from the frame body 40 and used like a paper. If the electrode protection cover is formed of a hard material, the liquid crystal display element 100 will not be mistaken for normal paper, and an accident such as throwing into the shredder can be prevented. Further, specific information may be printed on the edge portion (region 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 that performs display by switching between red selective reflection and a transparent state is disposed on the light absorption layer 121, and a display is displayed thereon by switching between green selective reflection and a transparent state. A green display layer 111G to be performed is stacked, and a blue display layer 111B to be displayed by switching between blue selective reflection and a transparent state is further stacked thereon.
[0023]
Each of the display layers 111R, 111G, and 111B is obtained by sandwiching the resin columnar structure 115, the liquid crystal 116, and the spacer 117 between the transparent substrates 112 on which the transparent electrodes 113 and 114 are formed, respectively. An insulating film 118 and an alignment control film 119 are provided on the transparent electrodes 113 and 114 as necessary. A sealing material 120 for sealing the liquid crystal 116 is provided on the outer peripheral portion (outside the display area) of the substrate 112.
[0024]
The transparent electrodes 113 and 114 are respectively drawn outward to connect to the 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. 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 having a specific wavelength is selectively reflected.
[0025]
The transparent electrodes 113 and 114 provided on the display layers 111R, 111G, and 111B are each composed of a plurality of strip electrodes arranged in parallel at fine intervals, and the direction in which the strip electrodes are arranged is perpendicular to each other. They are facing each other. The upper and lower strip electrodes are sequentially energized. That is, display is performed by sequentially applying voltages to the liquid crystals 116 in a matrix. 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 a liquid crystal exhibiting a cholesteric phase is sandwiched between two substrates, display is performed by switching the liquid crystal state between a planar state and a focal conic state. When the liquid crystal is in a planar state, light having a wavelength λ = P · n is selectively reflected when the spiral pitch of the cholesteric liquid crystal is P and the average refractive index of the liquid crystal is n. In the focal conic state, when the selective reflection wavelength of the cholesteric liquid crystal is in the infrared light region, it 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 absorption 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 absorption 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. Because of the transmission of light, it becomes possible to display black and display white by scattering in the focal conic state.
[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 the liquid crystal is in a focal conic arrangement, and the red display layer 111R is in a planar arrangement. By selecting the selective reflection state, red display can be performed. Further, the yellow display is performed by setting the blue display layer 111B in a transparent state in which the liquid crystal is in a focal conic arrangement and the green display layer 111G and the red display layer 111R in a selective reflection state in which the liquid crystal is in a planar arrangement. Can do. Similarly, red, green, blue, white, cyan, magenta, yellow, and black can be displayed by appropriately selecting a transparent state and a selective reflection state as the state of each display layer. Further, by selecting an intermediate selective reflection state as the state of each display layer 111R, 111G, 111B, an intermediate color can be displayed and 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 light in the long wavelength region has a higher transmittance 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 bright display can be performed. Therefore, the blue display layer 111B, the green display layer 111G, and the red display layer 111R are most desirable in order from the observation side (the direction of arrow A), and this state provides the most preferable display quality.
[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 for the transparent resin film include polycarbonate resin, polyether sulfone resin, polyethylene terephthalate resin, norbornene resin, polyarylate resin, amorphous polyolefin resin, and 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. In addition, a material having moisture resistance, gas barrier properties and the like and having necessary characteristics according to the environment and application to be used may be selected.
[0030]
A transparent electrode such as ITO (Indium Tin Oxide) can be used as the transparent electrodes 113 and 114, 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. For the lowermost transparent electrode 114, a black electrode including a role as a light absorber can be used.
[0031]
The insulating film 118 is made of an inorganic film such as silicon oxide or an organic film such as polyimide resin or epoxy resin so as to function also as a gas barrier layer, and prevents a short circuit between the substrates 112 and improves the reliability of the liquid crystal. The orientation control film 119 is typically polyimide.
[0032]
As the liquid crystal 116, those showing a cholesteric phase at room temperature are preferable, and a chiral nematic liquid crystal obtained by adding a chiral dopant to a nematic liquid crystal is particularly preferable.
[0033]
A chiral dopant is an additive having an action of twisting molecules of a nematic liquid crystal when added to the nematic liquid crystal. By adding a chiral dopant to the 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 the advantage that the pitch of the spiral structure can be changed by changing the amount of the chiral dopant added, whereby the selective reflection wavelength of the liquid crystal can be controlled. In general, the term “helical pitch” defined by the distance between molecules when the liquid crystal molecules rotate 360 ° along the helical structure of the liquid crystal molecules is used as a term representing the pitch of the helical structure of the liquid crystal molecules. .
[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 softens by heating and solidifies by cooling, does not cause a chemical reaction with the liquid crystal material to be used, and has 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. Examples thereof include resins, polyacrylonitrile resins, polyvinyl ether resins, polyvinyl ketone resins, polyvinyl pyrrolidone resins, polycarbonate resins, chlorinated polyether resins, and saturated polyester resins.
[0037]
The columnar structure 115 may be formed from a material that includes one or a plurality of these materials, or at least one of these materials or a mixture thereof.
[0038]
The substance is printed using a pattern so as to form a dot column shape as shown in FIG. 6 using a known printing method. 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 (cylinder, drum shape, polygonal column, etc.) are appropriately selected. In addition, it is more preferable to arrange the columnar structures 115 preferentially 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 pressurization are preferable. For example, it is possible to use glass fibers made finer, 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.
[0040]
In this way, the hard spacer 117 that keeps the gap between the two substrates 112 in a predetermined size, and the high thermoplasticity that is disposed in the display area based on a predetermined arrangement rule and adheres and supports the pair of substrates 112. By providing the resin structure 115 having 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 unevenness in arrangement, and generation of bubbles in a low temperature environment can be suppressed. it can.
[0041]
(Manufacturing example of 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 sputtering or the like and then patterning by photolithography.
[0042]
Next, a transparent insulating film and an orientation control film are formed on the transparent electrode formation 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 polyimide resin.
[0043]
Note that the orientation control film is usually not rubbed. Although the function of the alignment control film is not yet clear, it is thought that the presence of the alignment control film can give a certain anchoring effect to the liquid crystal molecules, and the characteristics of the liquid crystal display element change over time. Can be prevented. Further, a color filter function may be provided by adding a dye to these thin films to increase color purity and contrast.
[0044]
In this way, a resin structure is formed on the electrode formation surface of one substrate on which the transparent electrode, the insulating film, and the orientation control film are provided. The resin structure is a printing method, a dispenser method, or an inkjet method in which a paste-like resin material in which a resin is dissolved in a solvent is extruded with a squeegee through a screen plate, a metal mask, etc., and printed on a substrate placed on a flat plate It can be formed by a method in which a resin material is discharged onto the substrate from the tip of the nozzle, or a transfer method in which the resin material is supplied onto a flat plate or roller and then transferred to the substrate surface. . It is desirable that the height at the time of forming the resin structure is 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 sealing material is arranged in an annular shape that is continuous at the outer edge of the substrate. As with the resin structure described above, the arrangement of the sealing material is a method such as a dispenser method or an inkjet method in which a resin is discharged onto the substrate from the tip of the nozzle, a printing method using a screen plate, a metal mask, or the like, After forming the resin on a flat plate or a roller, it may be performed by a transfer method for transferring the resin onto a transparent substrate. Further, spacers are dispersed on the surface of at least one substrate by a conventionally known method.
[0046]
Then, the pair of substrates are overlapped so that the electrode formation surfaces face each other, and heated while being pressurized from both sides of the pair of substrates. For example, as shown in FIG. 7, the pressing and heating are performed by placing a substrate 112 a on which a resin structure 115 is formed on a flat plate 150, stacking a counter substrate 112 b, and heating from the end by a heating / pressure roller 151. It can be performed by passing between the roller 151 and the flat plate 150 while applying pressure. When such a method is used, a cell can be produced with high accuracy even when a flexible substrate such as a film substrate is used. If the resin structure is formed of a thermoplastic polymer material, the resin structure can be softened by heating and solidified by cooling, and the two substrates can be bonded together by the resin structure. When a thermosetting resin material is used as the sealing material, the sealing material is preferably cured by heating when the substrates are overlapped.
[0047]
In this superposition process, a liquid crystal material is dropped on one substrate, and the liquid crystal material is injected into the liquid crystal element simultaneously with the superposition of the substrates. In this case, a spacer may be included in the liquid crystal material in advance, and this may be dropped on the band electrode forming surface of at least one substrate.
[0048]
The liquid crystal material can be filled in the entire area of the substrate by dropping the liquid crystal material onto the edge of the substrate and spreading the liquid crystal material to the other end while overlapping the substrates with a roller. By doing so, it is possible to reduce entrainment of bubbles generated when the substrates are superposed on the liquid crystal material.
[0049]
After that, pressurizing the substrate is stopped at least until the substrate temperature is lowered below the softening temperature of the resin material constituting the resin structure, and further, when a photocurable resin material is used as a sealing material Then, light irradiation is performed to cure the sealing material.
[0050]
In the same procedure, the liquid crystal material is changed to one having a different selective reflection wavelength, and cells for blue display, green display, and red display are produced. The cells thus produced are stacked in three layers, and these are attached with an adhesive, and a light absorption layer is provided in the lowermost layer to form a full-color liquid crystal display element.
[0051]
(Power supply / 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 circuit is composed of a power source 135 such as a battery and a power 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, the other 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 conjunction with the central processing unit 51 to drive and control the liquid crystal display element 100.
[0053]
The central processing unit 51 starts to operate 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 that temporarily stores image data, and an image processing device that performs 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 that stores various control programs and a RAM 58 that temporarily stores various information. The central processing unit 51 receives signals from the operation keys 22, the power switch 23, and the mounting 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. Based on the data stored in the image memory 52, the LCD controller 55 controls the drive IC 59, sequentially applies a voltage between each scanning electrode and 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 it is taken out from the frame body 40. Further, after taking out, another display element 100 can be mounted and image writing can be continued.
[0056]
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), respectively, as shown in FIG. The scan electrodes R1, R2 to Rm are connected to the output terminal of the scan drive IC 131, and the signal electrodes C1, C2 to Cn are connected to the output terminal of the signal drive IC 132.
[0057]
The scan driving IC 131 outputs a selection signal to a predetermined one of the scan electrodes R1, R2 to Rm to be in a selected state, while outputting a non-selection signal to the other electrodes to be in a non-selected state. The scan driver IC 131 sequentially applies selection signals to the scan electrodes R1, R2 to Rm while switching the electrodes at a predetermined time interval. On the other hand, the signal driving IC 132 simultaneously outputs signals corresponding to image data to the signal electrodes C1, C2 to Cn in order to rewrite each pixel on the scanning electrodes R1, R2 to Rm in the selected state. For example, when the scan electrode Ra is selected (a is a natural number satisfying a ≦ m), the pixels LRa-C1 to LRa-Cn at the intersections of the scan electrode Ra and the signal electrodes C1, C2 to Cn are simultaneously rewritten. It is done. Thereby, the voltage difference between the scan electrode and the signal electrode in each pixel becomes the rewrite voltage of the pixel, and each pixel is rewritten in accordance with this rewrite voltage.
[0058]
Here, if the first threshold voltage for untwisting the liquid crystal exhibiting the cholesteric phase is Vth1, the voltage is set to a second threshold voltage Vth2 smaller than the first threshold voltage Vth1 after the voltage Vth1 is applied for a sufficient time. Lower to below to enter the planar state. Further, when a voltage not lower than Vth2 and not higher than Vth1 is applied for a sufficient time, a focal conic state is established. These two states are maintained stably even after the voltage application is stopped. Further, 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 method described above. 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 the pixels at once or for each scan electrode. For example, it has been found that when each pixel is reset to the focal conic state, a relatively long time is required in order to obtain a sufficient transparent state. Therefore, it is preferable to reset all the pixels to the focal conic state at the same time prior to the rewriting because the rewriting time can be shortened as compared with the case of resetting 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. Such a structure makes it possible to produce a liquid crystal display element that is light and excellent in display characteristics using a film substrate, and is easy to increase in size, has a relatively small driving voltage, and is excellent in various resistances such as being resistant to impact. It has characteristics and is particularly useful. However, the memory liquid crystal itself is not necessarily limited to this configuration, and the liquid crystal is dispersed in a conventionally known polymer three-dimensional network structure, or the polymer three-dimensional network structure is contained in the liquid crystal. The liquid crystal display layer can be formed as a so-called polymer dispersion type liquid crystal composite film.
[0061]
(Control procedure, see FIGS. 11 to 13)
Hereinafter, the control procedure processed by the central processing unit 51 in the display device 10 will be described in relation to the present invention.
[0062]
FIG. 11 shows the main routine of the central processing unit 51. Here, the central processing unit 51 is activated based on the power switch 23 being turned on, and the RAM 58, registers, and the like are initialized in step S1. Further, energization of each unit connected to the central processing unit 51 except for the booster circuit 137 is started.
[0063]
Next, after confirming that the liquid crystal display element 100 is mounted based on the signal from the sensor 46 in step S2, a liquid crystal display composed of the LCD controller 55 and the drive IC 59 (131, 132) is determined in step S3. The drive part of the element 100 is made into an operation state. 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 possible. Also, a power saving timer is started.
[0064]
Next, the subroutines of steps S4 and S5 are sequentially called to execute necessary processing. That is, the screen update is processed in step S4, and the drive IC 59 of the liquid crystal display element 100 is deactivated at a predetermined timing in step S5. That is, power saving processing for turning off the booster circuit 137 connected to the drive IC 59 is performed. These subroutines will be described later.
[0065]
Next, in step S6, it is determined whether or not there is an end command (such as turning off the power switch 23) from the user. If there is no end command, the process returns to step S4. And the energization to the central processing unit 51 itself is stopped.
[0066]
As described above, in the first embodiment, when the power switch 23 is provided and the rewriting of the display is not necessary, the operation of the central processing unit 51 is completely stopped and the standby power is made zero. A display device with high power saving characteristics can be obtained.
[0067]
FIG. 12 shows a subroutine for the screen update process executed in step S4. Here, first, in step S11, it is determined whether or not a reset key (one of the keys 22 shown in FIG. 1) for erasing the screen is turned on. If it is turned on, it is determined in step S12 whether the booster circuit 137 is on. If it is on, the screen is reset in step S15. On the other hand, if it is in the off state, the booster 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, for example, by writing on the liquid crystal display element 100 so as to fill the screen with black, white, or other single color. As a result, it is possible to erase an image that is no longer required to be displayed, or to erase an image that is still displayed and is not desired to be touched by another person's eyes.
[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 the external device (personal computer 1). The data transmission request is used when, for example, a predetermined image stored in the external terminal such as a calendar or schedule table is displayed on the sub display by operating the external terminal, or on a window displayed on the main screen of the external terminal. When another window is newly opened or closed, the 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 step S17 whether 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 in the off state, the booster 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 an off state. If it is in an off state, this subroutine is immediately terminated. If it is in the ON state, it waits for the power saving timer to count up in step S22, the power of the booster circuit 137 is turned off in step S23, and the power saving timer is reset in step S24. After rewriting the screen in this way, it is possible to save power by waiting for the timer to count for a predetermined time and then stopping the booster circuit 137 with high power consumption and continuing the display. Further, since the booster circuit 137 is turned off after a predetermined time has elapsed since the image was written (for example, after 5 minutes), the display device is in a standby state until the predetermined time elapses. Can be written. Therefore, the operability when the image writing is continued for a short time is good.
[0071]
(Display element after image writing)
As described above, the liquid crystal display element 100 on which an image has been written can be removed from the frame 40 and a new liquid crystal display element 100 can be attached to write the next image. By repeatedly 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 an image has been written and removed may be placed side by side on a support frame such as an easel. A large image can be displayed by dividing and writing one large image into a plurality of display elements 100 and arranging them.
[0072]
Further, when the liquid crystal display element 100 is taken out from the frame body 40, additional information may be written into the element 100. For example, if one large image is written by being divided into a plurality of liquid crystal display elements 100, the display position or the image relationship may be written in each element 100 to the extent that the display image is not damaged.
[0073]
Alternatively, the time when the element 100 has been removed from the frame 40 can be grasped by displaying the image writing date and time. 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. In this re-input, the screen may be reset once 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 (drive voltage, application time, etc.) according to the detected temperature may be provided.
[0074]
Further, in consideration of the case where the operator temporarily leaves the display device 10 or the like, in order to maintain the confidentiality of the display image, means for temporarily invisible the display screen, for example, wallpaper display means is used as 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 in 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 left and right surfaces of a case 201 that can be spread, a plurality of operation keys 204 that instruct display switching, page feed, and the like, and an external device. An IrDA terminal 205 for exchanging information with the LAN, a slot 206 for a LAN card for connecting to a LAN network, and a slot 207 for a memory card (ATA memory card, smart media, etc.) for storing image data and the like. ing. The housing 201 can be folded using the central support shaft 208 as a fulcrum.
[0076]
The liquid crystal display elements 202 and 203 have the same cholesteric phase as 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 unit, and touch panels 83 and 84. The CPUs 70 and 80 are provided with a RAM 91 and a flash memory 92, and issue commands to the 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 source. The main CPU 70 has a wake-up mode and a sleep mode. When writing an image, the main CPU 70 enters a wake-up mode, and enters a sleep mode when the image writing ends. In the sleep mode, power consumption is suppressed by stopping clock oscillation or stopping supply of clocks to internal circuits such as a memory, a register, and a counter. When the main CPU 70 is in the sleep mode, when it receives an interrupt signal from the sub CPU 80, it shifts to the wake-up mode.
[0079]
The sub CPU 80 also uses the battery 81 as a power source. The sub CPU 80 is always in an operating state, and can detect input from the touch panels 83 and 84 and the operation keys 204 even when the DC / DC converter 82 is off. The sub CPU 80 preferably has a low processing speed and 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 or not there is an input on the touch panel 83 or 84 in step S51 and whether or not there is an input to the operation key 204 in step S52. Wait until there is an input. If there is any input, the DC / DC converter 82 is turned on in step S53, an interrupt signal is given to the main CPU 70 in step S54 to start the main CPU 70, and data is transmitted to the main CPU 70 in step S55.
[0081]
On the other hand, as shown in FIG. 17, the main CPU 70 receives data from the sub CPU 80 in step S61, interprets / processes the data in step S62, and in step S63, based on the data, the liquid crystal display elements 202, 203. Display. Next, when the completion of the display update is confirmed in step S64, the operation end is notified to the sub CPU 80 in step S65, and the sleep state is entered in step S66.
[0082]
If it is determined in step S64 that the update has not been completed, for example, if a continuous key operation such as continuously pressing a predetermined operation key is performed for the purpose of continuous page feed, Returning to S62 and S63, display update is executed 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 the image is written, the circuits other than the circuit part necessary for the key input and the touch-down detection on the touch panel are turned off, or only a circuit with extremely low power consumption is energized. By controlling in this way, it is possible to effectively save power. Therefore, it is effective for power saving in a portable electronic device using a battery or the like as a power source as in the second embodiment.
[0085]
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 may immediately shift to the wake-up mode by key input and pen down to rewrite the image. Therefore, the operability is not impaired for power saving. In particular, in the case of continuous page feed operation, the drive circuit is kept in the on state continuously, so there is no hindrance to the operation, and in the case of a single operation, the drive circuit is immediately turned off to save power. The effect is kept high.
[0086]
Although the power switch is not provided in the second embodiment, the display content can be confirmed immediately if the electronic book apparatus 200 is opened when the operator needs it. If rewriting is instructed, the screen can be rewritten. Therefore, there is no problem that the power switch is forgotten to turn off and the battery is consumed, or the auto power off mechanism is activated and the display screen disappears.
[0087]
In addition, since the sub CPU 80 that always wakes up monitors the signal that triggers the wake-up of the main CPU 70, the main CPU 70 has one interrupt input terminal for wake-up from the sleep state. It's enough.
[0088]
In the second embodiment, the sub CPU 80 is always operated. However, a CPU having a sleep mode may be used to further save power. 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 according to the second embodiment, the use of a reflective liquid crystal display element is advantageous for outdoor use. That is, the display can be easily viewed without lowering the contrast under the external light, and the backlight for the display is unnecessary. From such a viewpoint, the second embodiment can be applied not only to the electronic book apparatus but also to various portable electronic devices. That is, the present invention is also effective for portable electronic devices such as mobile phones, PDAs, and portable audio devices that display the contents of storage media (for example, portable MD players and portable CD players).
[0090]
(Refer 3rd Embodiment and FIGS. 18-20)
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 can also send and receive e-mails, and includes a liquid crystal display element 301 for displaying various information, an operation panel 302 for a user to perform various inputs, a speaker 303 for a call, a microphone 304, An antenna 305 and the like are provided.
[0091]
A liquid crystal display element 301 is used that exhibits the same cholesteric phase as described in the first embodiment except that a touch panel is provided on the surface. On this liquid crystal display element 301, various information such as the other party's telephone number to be transmitted, an e-mail address, an electronic document, an image, transmission / reception date and time, a mark indicating the reception status of radio waves, and a battery state are displayed.
[0092]
FIG. 19 shows a control circuit of the mobile phone 300. This control circuit is configured around a CPU 310 that incorporates the functions of an LCD controller and performs overall control. The CPU 310 includes a ROM 311 and a RAM 312, and includes a power supply 313. The CPU 310 is connected to the liquid crystal display element 301, the operation panel 302, the illumination 315, the image memory 316, the image processing circuit 317, and a DC / DC converter 318 as a power supply unit.
[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, sender information). , Title, size, etc.) are displayed and stored.
[0095]
FIG. 20 shows a control procedure processed by the CPU 310. The CPU 310 wakes up based on an interrupt signal generated by a key operation on the operation panel 302 or an incoming call. When CPU 310 wakes up, it resets and starts a timer for shifting CPU 310 to the sleep state in step S71.
[0096]
When 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 DC / DC converter 318 is kept on until it is determined in step S75 that the key input is completed. If it is determined that the key input is completed, the DC / DC converter 318 is turned off in step S76. As a result, the key input of the other party's telephone number, mail address, document, etc. can be performed smoothly.
[0097]
Next, when it is confirmed in step S77 that a transmission command has been input, the transmission / call is processed in step S78. When the transmission / call is completed (YES in step S79), a sleep state is entered. 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 erased in step S81 and the sleep state is entered.
[0098]
Until the sleep timer counts up (NO in step S80), the key input is waited for 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, when CPU 310 wakes up by an incoming call (YES in step S84), data is received in step S85, and when reception is confirmed in step S86, DC / DC converter 318 is turned on in step S87. In step S88, the incoming call is displayed on the liquid crystal display element 301. 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 held by the memory property of the liquid crystal even if the driving unit of the liquid crystal display element 301 is turned off after display, and no trouble occurs. Further, the display can be visually recognized without a backlight, which is suitable for energy saving. In addition, 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 mobile phones but also to various information electronic devices. For example, the present invention can be applied to incoming information display in a portable device for mail, a pager, a facsimile, and the like. Furthermore, the present invention can be applied to display of program information in a radio receiver, a television receiver, a VTR, and the like.
[0102]
(Refer to the fourth embodiment, FIGS. 21 to 23)
FIG. 21 shows an online display terminal device 400 according to the fourth embodiment of the present invention. In this display terminal device 400, a plurality of devices 400 are connected to a single 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 surface, and displays advertisement information stored in a built-in nonvolatile memory or advertisement information transmitted from the host device 420 on the liquid crystal display element 401. The display terminal device 400 is turned on / off, the order of advertisement information to be displayed, and the like are based on instructions from the host device 420. Therefore, the display terminal device 400 includes a power supply unit but does not include a power switch.
[0103]
As the liquid crystal display element 401, an element exhibiting a cholesteric phase similar to that described in the first embodiment is used.
[0104]
FIG. 22 shows a control circuit of the display terminal device 400. This control circuit is configured around a CPU 430 that incorporates a ROM 431 and a RAM 432 and performs overall control. A driving IC 435 of the liquid crystal display element 401 is connected to the CPU 430 via an LCD controller 434, and a DC / DC converter 436, an image processing circuit 437, and an image memory 438 as a power supply unit are further connected. In addition, 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 processed by the CPU 430. The CPU 430 wakes up based on the interrupt signal from the host device 420, and processes reception of data from the host device 420 in step S101. When reception completion is confirmed in step S102, the DC / DC converter 436 is turned on in step S103. 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 to enter a sleep state.
[0106]
In addition, this 4th Embodiment is applicable not only to the usage method as an advertising board but to various online display terminal devices. For example, it can be used as a guide board, bulletin board, timetable, price tag, electronic newspaper, scoring board, conference material display board, and the like.
[0107]
(Fifth embodiment, see FIGS. 24-26)
FIG. 24 shows an electronic photo frame 500 according to the fifth embodiment of the present invention. In this electronic photo frame 500, the memory card 510 can be attached to and detached from the slot 502, and image data stored in the memory card 510 is read and displayed on the liquid crystal display element 501. As the liquid crystal display element 501, an element having a cholesteric phase similar to that described in the first embodiment is used.
[0108]
When the memory card 510 is loaded in 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. In addition, a timer may be incorporated so that images are updated sequentially at regular intervals.
[0109]
FIG. 25 shows a control circuit of the electronic photo frame 500. This control circuit is configured around a CPU 530 that performs overall control incorporating a ROM 531 and a RAM 532. A driving IC 535 of the liquid crystal display element 501 is connected to the CPU 530 via an LCD controller 534, and further, an image processing circuit 537 including keys 503 and 504, a DC / DC converter 536 as a power supply unit, and an image memory 538, respectively. 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 processed 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 completion of reading is confirmed in step S112, the DC / DC converter 536 is turned on in step S113. 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 to enter a sleep state.
[0111]
The electronic photo frame 500 shown in the fifth embodiment is used in a stand-alone manner, has no communication means, and has an advantage that no power is consumed by communication.
[0112]
In addition to the electronic photo frame, the fifth embodiment can be applied to a display device of a vending machine, a menu display device in a restaurant, a clock, a timer, and the like.
[0113]
(Other embodiments)
The liquid crystal display device and the display system according to the present invention are not limited to the above-described embodiments, 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 display element attaching / detaching mechanism are arbitrary. As for the liquid crystal, various cell configurations and driving methods can be employed.
[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, and shows a case where a display is installed vertically.
FIG. 2 is a perspective view showing the liquid crystal display device, and shows a case where the display is placed horizontally.
FIG. 3 is a perspective view showing a state in which a liquid crystal display element is taken out from the liquid crystal display device.
FIG. 4 is a cross-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.
7 is an explanatory view showing a manufacturing process of the liquid crystal display element. FIG.
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 driving 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 screen update subroutine.
FIG. 13 is a flowchart showing a power saving process subroutine;
FIG. 14 is a perspective view showing an electronic book device according to a second embodiment of the present invention.
FIG. 15 is a block diagram illustrating 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 apparatus.
FIG. 17 is a flowchart showing a control procedure of a main CPU in the electronic book apparatus.
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 CPU control procedure in the mobile phone.
FIG. 21 is a perspective view showing an online display terminal device according to the 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 the 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 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 the 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 ... Online 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 (5)

A reflective liquid crystal display element comprising at least one display layer having memory properties, using a liquid crystal exhibiting a cholesteric phase at room temperature and using an alignment control film not subjected to rubbing treatment;
A driving circuit for writing an image so that one display layer is displayed for each pixel in a planar state, a focal conic state, and a halftone display state;
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;
A power switch for turning the main power on and off;
A reset key for instructing to reset the screen by writing to fill the display screen of the liquid crystal display element with a single color, provided independently from the power switch;
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 are inactivated, and a part of the power supply circuit or / and Control means for maintaining the image in a visually recognizable state using the memory property and reflection characteristic of the liquid crystal display element even after the internal circuit of the data processing device is inactivated.
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 a liquid crystal in which a sufficient amount of a chiral dopant is added to a nematic liquid crystal at room temperature to display a cholesteric phase. apparatus.   The liquid crystal display device according to claim 1, wherein the liquid crystal display element is capable of full color display.   4. The liquid crystal display device 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. A plurality of liquid crystal display devices according to claim 1;
A host device to which the plurality of liquid crystal display devices are connected;
A display system characterized by comprising:

Images