JPS62266521A - Display panel - Google Patents

Abstract

PURPOSE:To attain writing display based upon hand writing, reading, erasing, etc., and to obviate consumables by providing the titled device with an optical modulation means for holding a substrate layer for executing optical modulation at the impression of an electric field and electrodes arrayed like a matrix, and an input means. CONSTITUTION:Since scanning electrodes 21 and information electrodes 22 are arrayed like a matrix, an electric field is generated on an intersecting point between the scanning electrode and its opposed information electrode by impressing prescribed pulses to respective electrodes, so that an image is displayed. Since the scanning electrode 21 arranged on the back side of the panel has an information electrode formation part (a) and a non-formation part (b), the orientating state of liquid crystal in the area (b) can be inverted by applying a prescribed voltage between an input pen 3 and the scanning electrode 21 on the side opposed to the part (b). Since ferroelectric liquid crystal can maintain one orientating state even if no electric field is applied, characters, graphics or other information can be displayed and written by generating electric fields by the electrodes or the input pen 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a display panel, and more particularly to a display panel capable of +sf writing and erasing.

[Summary of the Disclosure] This specification and drawings describe a writable/erasable display panel that includes one stage of optical modulation sandwiching a material layer that produces optical modulation by application of an electric field and electrodes arranged in a matrix, and a display panel that can be written and erased. By using a display panel equipped with a photoelectric transformer and an input stage that applies an electric field to the stage, in addition to the normal display function, it is possible to write, display, read, erase, etc. using f writing, making it a durable consumable item. This makes it possible to construct a multi-aperture display device that does not require a.

[Prior Art] Conventionally, as a device having this type of writing/displaying function,
A display with a digital date on the display screen.

Also known as a blackboard, whiteboard, or electric blackboard shade.

[Problems to be Solved by the Invention] Among these conventional devices, in the former, the overlapped portion of the digitizer is thick, and the writing position and the visible position of the image are misaligned due to the thickness. There were drawbacks such as. In addition, the latter requires consumables such as chalk and ink, and also requires digitization for sending and receiving! ! There was a drawback that it was not possible to reproduce and display the J image signal and the like.

The present invention has been made in order to solve the drawbacks of the prior art described in E, and provides a display panel which has a function of displaying written information by manual divination, reading and erasing the displayed image, as well as a function of displaying an image signal shade. The purpose is to

[F stage for solving problems] As shown in FIGS. 1 and 3 of the embodiment drawings, the present invention provides a transparent substrate 17 provided with a polarizing plate 15 and a transparent substrate provided with a polarizing plate 1B. 18, the scanning electrode 21 and the information electrode 2
2 are arranged in a matrix, and a ferroelectric liquid crystal layer 19
A ferroelectric liquid crystal board (hereinafter referred to as FLC board) 13, which is an optical modulation means, sandwiching an optical modulation substance that exhibits bistability, such as a ferroelectric liquid crystal board (hereinafter referred to as FLC layer), and This is a display panel equipped with an input pen 3 which is an input stage that generates an electric field that reverses the orientation state.

[Sakukawa] In FIG. Since the g-electrons 8i22 are arranged in a matrix, when a predetermined pulse is applied to each electrode, an electric field is generated at the intersection of the scanning electrode and the opposing information electrode, and the image is displayed on the same principle as a normal liquid crystal panel. is displayed.

- On the other hand, the scanning electrode 21 arranged on the back side of the panel has a part (a in the figure) where the information electrode 22 is provided on the opposite surface,
Since there is a part (b in the figure) that is not provided, by applying a predetermined voltage between the input pen 3 and the scanning electrode on the side corresponding to the part (b), the orientation of the liquid crystal in the area (b) in the figure can be adjusted. A ferroelectric liquid crystal whose state can be reversed maintains one orientation state even when no electric field is applied, so by generating an electric field with an electrode or input pen, it is possible to display one character, one figure, and other information. , writing becomes possible. On the other hand, the image is erased by changing the electric field between the two electrodes or between the input pen and the electrode, the polarity of which is opposite to that at the time of display input.

[Embodiment] FIG. 2 is an overall configuration diagram showing an embodiment of a display device using a display panel according to the present invention. In FIG. 2, the display device 20 is composed of a main body cover 14 having a display panel 1 therein, and an input pen 3 connected to the device via a cord 4. It is supported by two leg parts 6. Further, 7 in the figure is an eraser which will be described later. FIG. 1 is a sectional view of the main part of the display panel 1. As shown in FIG. In FIG.

The display panel 1 is roughly composed of an FLC board 13 and a backlight 9 disposed inside the board, and is further provided with a reading section 8, which will be described later.

As shown in the partial cross-sectional view of FIG. 3, the FLC board 13 has a transparent plate (
The front side provided with the plate 17, the polarizing plate 18, and the information electrode 22 (
11: a transparent substrate 18 (closed side), and one FLG layer sandwiched between these two store boards. The polarizing plates 15 and 16 are mainly made of PVA or the like and have a thickness of 50 to 110 mm.
They are polarizing sheets of about 0p, and are arranged in a crossed nicol shape of 7 m so that their polarization axes are perpendicular to the intervening space. As the transparent substrate 17 on the back side, a glass plate with a thickness of about 4 to 8 ml11 is used. On the other hand, the transparent Jjj[+8
For example, glass or P with a thickness of about 50 to 300 μl is used.
Transparent resin such as E↑sheet is used. Furthermore, as the scanning electrode 21 and information electrode 22 on the 2Si plate, ITO (
A plurality of transparent conductive films such as Indium-Tin-Owide (Indium-Tin-Owide) formed into stripes with a thickness of about 500 to 2000 Å by sputtering or the like is used. An alignment control film (not shown) is uniformly formed on the surface of the striped electrode M/1, and is maintained at a layer thickness of about 1 to 2 gm by spacers (not shown) such as beads.

The optical modulating substance used in the present invention is one that forms a first optically stable state (for example, a bright state) and a second optically stable state (for example, a dark state) depending on the applied electric field. A material having at least two stable states with respect to an electric field, in particular a liquid crystal having such properties, is used.

As the liquid crystal having bistability that can be used in the present invention, chiral smectic liquid crystal having ferroelectricity is most preferable, among which chiral smectic C phase (Sa
c”), H-phase (S-phase H) liquid crystals are suitable.For this ferroelectric liquid crystal,
Physique Lucille” (“LE JOllRNAL
DE PI (YSTQUE LETTER9''')19
1975, No. 3B (L-89), ``Ferroelectric Liquid Crystals J (rFerroel
etricLiquid CrystalsJ);“
Applied-74 Zix-L, Tars” (“App
98
Year 0, No. H(11), "Submicro Second Bistiple Electro-Optic Switching in Liquid Crystals"
5econd B15table Electro
optic Switching in Liquid
CrystalsJ); “Solid State Physics 71981,
ferroelectric liquid crystals disclosed in these publications can be used in the present invention.

This ferroelectric liquid crystal will now be explained with reference to FIGS. 7 and 8.

FIG. 7 schematically depicts an example of a ferroelectric liquid crystal cell used in the present invention. 31 and 3i' are In, + 0
3, 5n02 and ITO (Indium-Tin-Ox
Substrate (glass plate) coated with a transparent electrode such as
In between, liquid crystal of S-Zen-C-Front phase with the liquid crystal molecular layer 32 oriented perpendicularly to the glass surface is sealed. Shown with a thick line! A33 represents a liquid crystal molecule, and this liquid crystal molecule -33 has a dipole f moment (P, )34 in a direction perpendicular to the molecule. ,! ! Boards 31 and 31
When a voltage higher than a certain dark value is applied between the electrodes on ', the helical structure of the liquid crystal component F33 unwinds, and the dipole r moment (
P, ) 34 are arranged so that the liquid crystal molecules 33 are all oriented in the direction of the electric field.
The orientation direction can be changed. The liquid crystal molecules 33 have an elongated shape and exhibit refractive index anisotropy in the long and short axis directions. Therefore, for example, if polarizers are placed above and below the glass surface in a cross-niffle positional relationship, ,? 1
It is easily understood that this is a liquid crystal optical element whose optical properties change depending on the polarity of the applied voltage.

FIG. 8 shows a preferred embodiment of a liquid crystal element used in the present invention. In other words, when the thickness of the liquid crystal cell is made sufficiently thin (for example, one cell), the helical structure of the liquid crystal molecules is removed (non-helical structure) even when no electric field is applied, as shown in Figure 8. , its dipole moment) P or P'
is either upward (34a) or downward (34b). When such a cell is subjected to an electric field E or E' with a different polarity of a certain threshold A1 or more for a predetermined time as shown in FIG. 34a or downward 34b, and accordingly the liquid crystal molecules are in the first alignment state 35.
or the second orientation state 35'.

An optical modulation element using such a forced liquid crystal has an electric field E
When the voltage is applied, the liquid crystal molecules are aligned in the first alignment state 35, but this state is stable even when the electric field is turned off. When an electric field E' in the opposite direction is applied, the liquid crystal molecules are aligned to the second alignment state 35' and change their orientation, but they remain in this state IE even after the electric field is turned off. Further, as long as the applied electric field E does not exceed a certain value of A/1, each orientation state is maintained. In order to effectively realize such fast response speed and bistability, it is generally preferable for the cell to be as thin as possible.

A thickness of 0.5μ to 20μ, particularly IJL to 5, is suitable. A liquid crystal-'pneumostatic device having a matrix electrode structure using a ferroelectric liquid crystal of this type has been proposed, for example, by Clark and Ragabal in US Pat. No. 4,387,924.

FIG. 4 is a perspective view of the input pen 3. In FIG. 4, the manual pen 3 has a nib 24 at its tip. A mode changeover switch 25 is provided at the top, and a voltage pulse for writing is applied to the pen tip 24, which is the tip electrode portion, through the cord 4. The voltage applied to the input pen is on the order of 50-500 V, but this value depends on the characteristics of the liquid crystal material and the writing speed. Incidentally, the normal writing speed is 0.1~10ss/
It is about am. The pen tip 24 has the function of a writing electrode and a switch, and by lightly pressing the pen tip 24 against the writing display surface 2, the pen tip 24 can be opened.
4, the write voltage pulse is output. Furthermore, since there is no need for a current to flow to invert the liquid crystal layer, it is advisable for safety to apply a resin coating or the like to the tip of the input ben.

Next, internal writing and display using scanning and information electrodes will be explained with reference to FIG. In FIG. 3, F corresponds to the front side where display or writing is performed, and R corresponds to the back side where the front backlight 9 is arranged. Further, it is assumed that all screens are unified to a "bright" state.

When writing and displaying using internal electrodes, the intersection of the information electrode 22 on the F side with the scanning electrode 21 on the R side,
That is, area a in FIG. 3 is used.

First, a negative voltage is applied to the scanning electrode 21 on the R side, and the information electrode 22-1 selected from among the information electrodes 22 on the F side is
- Apply voltage. By applying this voltage.

An electric field exceeding the threshold of the sandwiched ferroelectric liquid crystal is generated,
The orientation state of the FLC layer 19 in a portion corresponding to region a in FIG. 3 is reversed from the first stable state to the second stable state.

Here, the first stable state is "
When the second stable state is set to be a "dark" state in which backlight light is not transmitted, the area A corresponding to the area a becomes a "dark" display state by applying the above voltage. . At this time, the information electrode that is not selected, for example 22-2
.

If 22-3 is set to zero potential, the "bright" display state can be maintained as it is.

Next, write from the outside using the input pen and display it in the third screen.
This will be explained with figures.

When writing and displaying using an input pen, the part where the information electrode 22 on the F side does not intersect with the scanning electrode 21 on the R side, that is, the area b in FIG. 3 is used. First, set the mode changeover switch 25 of the input pen 3 to g-in mode,
The scanning electrode 21 is set to zero potential. Then, the pen tip 24 is brought into contact with the writing display surface 2, and a positive voltage is applied to the pen tip. By applying this voltage, a voltage exceeding the threshold of the ferroelectric liquid crystal is applied between the pen tip 24 and the scanning electrode 21, and an electric field is generated to invert the liquid crystal, causing the FLC in the portion corresponding to area b in FIG. The orientation state of layer 19 is reversed from the first stable state to the second stable state. As a result, part B in FIG. 3 becomes a "dark" display state, and the content filled in by the input pen is displayed.

In the above embodiment, the case where the entire surface is "bright" and the deep display is performed in "Sho" is described, but by appropriately selecting the arrangement of the polarizing plate and the direction of applied voltage, the entire surface can be "dark". 9 of “Ming” on the screen! It is also possible to perform a j-inclusive display.

Then by internal electrodes or input pen like this;!
An example of i-inclusive display will be explained in more detail with reference to FIG. Figure 6 is a configuration diagram of the matrix electrode, and S1 in Figure 1.
~S/ is a back electrode corresponding to the scanning electrode 21, and II
``I15 is a pole on the surface corresponding to the information electrode 22.'' In the following explanation, all screens are initially set to ``bright''.
It is assumed that the state is unified and unified.

When displaying using signals from external storage means, reading means, etc. (not shown), the back electrodes are sequentially scanned from 51 to St, and image information is selectively sent to the front electrodes 11 to 115 in synchronization with this. For example, apply 0 to display an image.
When displaying rAJ on the right side of FIG. 6, first, the back electrode S1 is set to 1, and the other back electrodes are set to Ov. -・way,
A voltage of +V is applied to the surface electrode IM', and the other surface electrodes are set to Ov. As a result, a voltage of 2cm (a voltage higher than the threshold of the liquid crystal) is applied to the intersection of Sl and II2, and the orientation state is reversed so that "r dark" is displayed in the 0th order.

The back electrode S2 is set to 1, and the other back electrodes are set to OV.

Further, a voltage of +V is applied to the surface electrodes Ill and Il:l, and the other surface electrodes are set to Ov. As a result, due to the same effect as in L, the intersections of S2 and Ill, S2 and II3 are
"dark" is displayed. By sequentially applying such voltages from the top, the letter "A" is displayed. In this case 1
The voltage applied to the front electrode needs to be a voltage that is lower than the threshold of the liquid crystal compared to the voltage applied to the back electrode, and from the viewpoint of driving, it is preferably the same potential as that of the back electrode.

Next, when writing "A" on the left side of FIG. 6 with the input pen 3, first, a negative voltage is applied to all the back electrodes 51, and a positive voltage is applied to the input pen 3. Then, when you slide the pen in an "A" shape on the screen E, the area shown in Figure 3 (for example, the part between A voltage of 1 is applied, and the character "A" is written as shown in FIG. At this time,
The voltage applied to the back electrodes 5I-5r may be not only a negative voltage but also a zero or positive voltage, but in order to avoid increasing the voltage at the pen tip, it is preferable to set it to the opposite polarity to that of the input pen.

As described above, according to the present invention, it is possible to write characters, figures, etc. in exactly the same way as when drawing on a whiteboard with a normal pen.

Furthermore, it is possible to eliminate the misalignment between the insertion position and the image position. Furthermore, since the image displayed by the scanning electrode and the information electrode and the image written by the input pen are recorded in different areas, they can be overlapped.

Next, the case of erasing one displayed image will be explained.

The erasure of the image displayed by the scanning electrode and the information electrode is
This can be done by applying a voltage of opposite polarity to that during writing. In this case, full or partial erasing can be achieved by appropriately selecting the electrodes. When erasing an image written with the input pen 3, use the mode selector switch 25 provided at the top of the input pen 3. of,
When the switch is switched from the write mode to the erase mode, the polarity of the voltage pulse applied to the pen tip is reversed, and becomes the opposite polarity to that at the time of writing. Therefore, when the input pen switched to erase mode is suppressed and scanned over the already written image E, an electric field opposite to that during writing is applied to the ferroelectric liquid crystal, so the orientation state is the first stable state, That is, the state returns to the "bright" state, and the written image in that portion is erased.

Furthermore, the case where erasing is performed using the eraser 7 shown in FIG. 2 will be described.

FIG. 5 is a perspective view of the eraser 7. In FIG. 5, the eraser 7 ii is roughly composed of an electrode 2B and a switch-cum-electrode support 27, and an erasing voltage pulse is changed through a cord 4. When this eraser 7 is pressed against the writing display surface 2, the upper electrode support 27 is slightly pushed into the display surface, and at the same time an erasing voltage pulse is generated from the electrode 2B.
That is, a pulse having a polarity opposite to that of the write voltage pulse is output. Therefore, as in the case of erasing with a manual pen, if the eraser 7 is suppressed and scanned over an image already written with an input pen, that portion of the written image will be erased.

Next, the function of reading a written image will be explained. In FIG. 1, the reading unit 8 includes lenses 7, IO1, photoelectric conversion elements 11. It is composed of an erasing head 12.

The lens array IO is a one-dimensional lens array of a refractive index distribution type that projects an image of the writing/displaying surface 2L onto the photoelectric conversion element 11. The photoelectric transducer) 11 is a CCD (Charg
It is formed into a long one-dimensional array, similar to the lens array described above. Further, the erasing head 12 has microelectrodes of 0.8 + s x O, 8 m - formed in a one-dimensional array with a pitch of 1ff and 111.

According to the configuration shown in FIG. 7tS1, characters, figures, etc. written on the FLC board 13 are sequentially converted into image signals as the reading section 8 moves in the direction of the arrow. That is, Nfi-
When the FLC board 13 is irradiated with light from the surface backlight 9, light corresponding to brightness and darkness is sequentially projected onto the photoelectric variable sensor 7-11 through the lens array IO.

The photoelectric conversion sensor 7-11 converts the projected image information into a digital signal and outputs it to an external printer or the like. Therefore, by connecting a telephone line or various communication terminals to this reading unit 8, it is possible to send one image information to a remote location,
It is also possible to save it on a floppy disk or the like.

On the other hand, the erasing head 12 is in contact with the FLC board 13, and by applying an erasing voltage pulse to this head, the displayed image can be erased in exactly the same manner as erasing using the eraser described above. In this case, arbitrary erasing such as selective partial erasing or entire erasing can be performed by appropriately controlling the application of the erasing voltage pulse to each electrode.

Further, in the present invention, when an erasing voltage is applied to the eraser, the current A1 charged in the capacitance between the eraser and the information electrode and between the eraser and the scan electrode is detected, so that the erase voltage is applied to the display surface. By detecting the position at and feeding it back, it is also possible to erase the image embedded by the information electrode. In this case, the scanning electrodes and the information electrodes can be erased in real time by alternately operating the position detection mode and the information mode.

[Effects of the Invention] As explained above, the display panel according to the fourth aspect of the present invention can reduce the thickness of the panel itself, and also has the following advantages:
You can write and erase characters, figures, etc. in exactly the same way as when drawing on a whiteboard with a regular pen. Furthermore, it is possible to eliminate the discrepancy between the writing position and the image position.

Also, due to the matrix electrode provided inside.

In addition to being able to arbitrarily display image signals from the outside, they can also be erased using the internal electrodes, and furthermore, it is also possible to overwrite them with an input pen. in this case,
In either case, erasable JE products such as chalk and ink can be made unnecessary. On the other hand, by reading the displayed image information, it is also possible to output it to an external printer, and it is also possible to erase it using the erasing head of this reading section.

In this way, by using the display panel according to the present invention, a multifunctional display device can be constructed.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of the display panel, Figure 2 is an overall configuration diagram of the display device, Figure 3 is a partial sectional view of the FLC board, Figure 4 is a perspective view of the input pen, and Figure 5 is the eraser. A perspective view, FIG. 6 is a configuration diagram of a matrix electrode, and FIGS. 7 and 8 are schematic diagrams of a liquid crystal cell. 1: Display panel, 2: Writing/display surface. 3: Human pen, 7: Eraser. 8: Reading section. 13: FLC (ferroelectric liquid crystal) board, 15, 18: polarizing plate. 1? , 18: Transparent substrate, 19: FLC layer. 21: Scanning electrode, 22: Information electrode.

Claims (2)

[Claims] (1) A scanning electrode and an information electrode are arranged in a matrix between a pair of transparent substrates having a polarizing plate, and at least two
an optical modulation means sandwiching an optical modulation material having two stability, and an input means for generating an electric field for reversing the orientation state of the optical modulation material; A display panel characterized in that it displays and erases images and also writes images using the input means. (2) The optical modulation means is provided with a one-dimensional array of photoelectric conversion elements and an erasing head, the photoelectric conversion elements read and output the displayed image, and the erasing head erases the image. A display panel according to claim 1.