JP2001275128A - Image display device, display method and writing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image display device that can display easy to see information for a viewer without a change in scenes in the dark on an entire screen at every addition/rewrite of characters/conversion, and to obtain a display method and a writing method. SOLUTION: The information display device uses a liquid crystal set to a cholesteric phase, the liquid crystal is brought into a transparent state to display a background and into a selective reflecting state to display information. For example, in the display device where three liquid crystal display layers selectively reflecting R, G, B lights are layered, each display layer is reset to a focal conic state to display a background in black, prescribed pixels of each display layer are set to a planar state to display a character 'A' in white. Then in the case of adding a character 'B', the prescribed pixels of each display layer are newly set to the planar state to display characters 'AB' in white.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an information display device, a display method, and a writing method.

[0002]

2. Description of the Related Art In a display device in which a liquid crystal exhibiting a cholesteric phase such as a cholesteric liquid crystal or a chiral nematic liquid crystal is sandwiched between two substrates, when a relatively high-energy voltage is applied, the liquid crystal enters a planar state. Light of a wavelength is selectively reflected. When a voltage of relatively low energy is applied, the liquid crystal enters a focal conic state and transmits visible light. When a light absorbing layer is provided on the back surface of the substrate, black display can be performed in the focal conic state, and selective reflection color can be displayed in the planar state.

A liquid crystal exhibiting this kind of cholesteric phase is:
After the information is displayed, the display is maintained even when the application of the voltage is stopped, and the display is of an energy-saving type, which is suitable for a portable display device powered by a battery.

By the way, in a display panel using a liquid crystal exhibiting a cholesteric phase of this kind, when performing full-color display, usually, three layers of blue, green, and red display layers are sequentially stacked from the observation side. Can be When performing character input or the like on such a display panel, for example,
As shown in FIG. 19 (A), white is used as a background color in which three display layers respectively reflecting R, G, and B light are selectively reflected (planar), and displayed (for example, the character “A”). May be displayed in black in a light transmitting (focal conic) state. In this case, the character "A" is replaced by the character "B"
In order to additionally write, it is conceivable that the screen is temporarily reset to black, which is the focal conic state, and then pixels other than the character "AB" are set in the planar state to display the character "AB".

[0005] Further, as shown in FIG. 19 (B), when a character inputted as "Komatsu" is converted into "Komatsu",
It is conceivable that the screen is temporarily reset to black, which is the focal conic state, and then pixels other than the conversion character "Komatsu" are set to the planar state.

However, in the display method, the entire screen is reset to the focal conic state every time additional writing, rewriting, or character conversion is performed, so that the entire screen becomes black in which the light absorbing layer on the back surface is observed. Blackout,
It was very difficult for the observer to see.

SUMMARY OF THE INVENTION An object of the present invention is to provide an information display device, a display method, and a writing method that are easy for an observer to view without turning over the entire screen every time a character is additionally written, rewritten, or converted.

[0008]

To achieve the above object, an information display device according to a first aspect of the present invention is an information display device which displays information after resetting a previous state. A display mode is provided in which a part of the display area is set to a color observed at the time of resetting.

That is, the information display device according to the first invention is:
In the display mode, when resetting the previous state when displaying information, the information is reset with the same color as the background color up to that time, so that every time the information is displayed such as additional writing, rewriting, or conversion of the character, the entire screen is different. It is possible to prevent the color from being changed to be difficult to see.

[0010] In the information display device according to the first aspect of the invention, a display device including a liquid crystal exhibiting a cholesteric phase can be employed. In this case, a display unit that can maintain display in a state where no voltage is applied may be used.

Further, in the information display device according to the second invention, in the information display device in which at least two display layers including a liquid crystal exhibiting a cholesteric phase are laminated, the first display layer is formed in at least a part of the display region. There is provided a display mode in which the background is displayed in the selective reflection state, and the information is displayed in the second reflection layer in the selective reflection state.

That is, in the information display device according to the second aspect of the present invention, the background is fixed to the color in which the first display layer is set to the selective reflection state, and the second display layer is set to the selective reflection state. Display information. Therefore, every time information is displayed, such as appending, rewriting, or converting characters, the screen is completely reset and the color does not change. This makes it easy for the observer to see, and the background can be a color other than black. is there.

Further, in the information display device according to a third aspect of the present invention, in the information display device in which at least two display layers each including a liquid crystal exhibiting a cholesteric phase are stacked, at least a part of the display region includes the first and second display layers. The display layer is set to a light transmitting state to display a background, the first display layer is set to a selective reflection state to display fixed information, and the second display layer is set to a selective reflection state to display variable information. It has a display mode.

That is, in the information display device according to the third aspect of the present invention, the first and second display layers are in a state of being in a focal conic state in which light is transmitted as a background (black background), and the first display is performed. The layer is set to a selective reflection state to display fixed information, and the third display layer is set to a selective reflection state to display variable information. Therefore, every time information is displayed, such as appending, rewriting, or converting characters, the screen is completely reset and the color does not change. This makes it easier for the observer to see, and also displays fixed information and variable information in different colors. It becomes possible. When the fixed information and the variable information are displayed at different portions, the visibility is further improved.

According to a fourth aspect of the present invention, there is provided an information display device using a liquid crystal exhibiting a cholesteric phase.
When performing display based on text data, the liquid crystal is set in a light transmitting state to display a background, and the liquid crystal is set to a selective reflection state to perform display based on the text data.

That is, since the display based on the text data is performed by setting the liquid crystal in the selective reflection state with the liquid crystal set in the light transmission state as a background, the entire screen is reset at the time of text display, and the display is discolored and becomes difficult to see. Is prevented.

An information display device according to a fifth aspect of the present invention is an information display device including a display unit using a liquid crystal exhibiting a cholesteric phase and information input means. The background is displayed by setting the liquid crystal in a light transmitting state, and then the input information is displayed by setting the liquid crystal in a selective reflecting state.

That is, since the liquid crystal is selectively reflected on the background in which the liquid crystal has been displayed in the light transmitting state in advance, the display according to the information input is performed. It is prevented that it becomes difficult to see.

In the display method according to a sixth aspect of the present invention, when the first display is reset from the first display and updated to the second display, the background colors in the first and second displays are reset at the time of the reset. Associated with observed color.

That is, since the color observed at the time of resetting is associated with the background color in the first and second displays, it is possible to prevent the entire screen from being discolored when the display is updated and becoming difficult to see. In the display method according to the sixth aspect, when the background color in the first and second displays is the same as the observation color at the time of resetting, the effect of preventing discoloration is enhanced.

A writing method according to a seventh aspect of the present invention is a writing method using a display device having a display unit including a plurality of stacked display layers and input means, wherein a background is displayed on the first display layer. In addition to the display, an image corresponding to the input information is displayed on the second display layer.

That is, since the background and the image corresponding to the input information are displayed on different display layers, it is possible to prevent the entire screen from being reset during writing and from being discolored and difficult to see. In the writing method according to the seventh aspect, the plurality of display layers include a layer for displaying fixed information.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of an information display device, a display method and a writing method according to the present invention will be described below with reference to the accompanying drawings.

(Liquid Crystal Display Device, See FIG. 1) First, a liquid crystal display device having a built-in liquid crystal exhibiting a cholesteric phase constituting a display device will be described.

FIG. 1 shows a reflection type full-color liquid crystal display device using a simple matrix drive system. 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 display is performed thereon by switching between green selective reflection and a transparent state. Are stacked, and a blue display layer 111B for performing display by switching between blue selective reflection and a transparent state is further stacked thereon.

Each display layer 111R, 111G, 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. Transparent electrode 11
An insulating film 118 and an orientation control film 119 are provided on the 3, 114 as needed. Further, a sealing material 1 for sealing the liquid crystal 116 is provided on an outer peripheral portion (outside the display area) of the substrate 112.
20 are provided.

The transparent electrodes 113 and 114 are driven
C131 and 132 (see FIG. 2), and a predetermined pulse voltage is applied between the transparent electrodes 113 and 114, respectively. 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.

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 at a fine interval, respectively. They are opposed so as to be at right angles. Current is sequentially applied to these upper and lower strip electrodes. That is, display is performed by sequentially applying voltages to the liquid crystal 116 in a matrix. This is referred to as matrix driving, and a portion where the electrodes 113 and 114 intersect constitutes each pixel. By performing such matrix driving for each display layer, the liquid crystal display element 100
To display a full-color image.

More specifically, in a liquid crystal display device in which a 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. Also,
In the focal conic state, the light is scattered when the selective reflection wavelength of the cholesteric liquid crystal is in the infrared light range, and transmits visible light when the wavelength is shorter than that. Therefore, by setting the selective reflection wavelength in the visible light range 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 range and providing a light absorption layer on the side opposite to the observation side of the element, light in the infrared light range is reflected in the planar state, but the wavelength in the visible light range is reflected. Is transmitted, so that a black display and a white display due to scattering in the focal conic state are possible.

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 formed of a liquid crystal. A red display can be performed by setting the array in the selective reflection state. Also, the blue display layer 111B
Is set in a transparent state in which liquid crystals are in a focal conic arrangement, and the green display layer 111G and the red display layer 111R are in a selective reflection state in which liquid crystals are in a planar arrangement, whereby yellow display can be performed. 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. Further, by selecting an intermediate selective reflection state as the state of each of the display layers 111R, 111G, and 111B, an intermediate color can be displayed, and the display layer can be used as a full-color display element.

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 material to a nematic liquid crystal is suitable.

The chiral material is an additive having a function of twisting the molecules of the nematic liquid crystal when added to the nematic liquid crystal. By adding a chiral material to a nematic liquid crystal, a helical structure of liquid crystal molecules having a predetermined twist interval is generated, thereby exhibiting a cholesteric phase.

Note that the memory liquid crystal itself is not necessarily limited to this structure, and the liquid crystal is dispersed in a conventionally known polymer three-dimensional network structure, or the polymer three-dimensional structure is contained in the liquid crystal. The liquid crystal display layer can be formed as a so-called polymer dispersed liquid crystal composite film having a network structure.

(Driving Circuit, See FIG. 2) As shown in FIG. 2, the pixel configuration of the liquid crystal display element 100 includes a plurality of scanning electrodes R1, R2 to Rm and signal electrodes C1, C2 to Rm.
It is represented by a matrix with Cn (m and n are natural numbers). 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 signal drive IC.
It is connected to the output terminal of C132.

The scan driving IC 131 includes scan electrodes R1, R
A selection signal is output to a predetermined one of 2 to Rm to be in a selected state, and a non-selection signal is output to other electrodes to be in a non-selected state. The scan driving IC 131 sequentially switches the scan electrodes R1 and R2 while switching the electrodes at predetermined time intervals.
To Rm. On the other hand, signal drive 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 scanning electrodes R1, R2 to Rm in the selected state. For example, when the scanning electrode Ra is selected (a is a natural number satisfying a ≦ m), the scanning electrode Ra and each signal electrode C1, C2
Pixels LRa-C1 to LRa-Cn at the intersection with Cn are simultaneously rewritten. Thereby, the voltage difference between the scanning electrode and the signal electrode in each pixel becomes the rewrite voltage of the pixel, and each pixel is rewritten according to this rewrite voltage.

The driving circuit includes a central processing unit 135, an image processing unit 136, an image memory 137, a controller 133,
134 and drive ICs (drivers) 131 and 132. Based on the image data stored in the image memory 137, the controllers 133 and 134
31 and 132, and sequentially applies a voltage between each scanning electrode and signal electrode of the liquid crystal display element 100,
Write the image at 00.

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 smaller than the first threshold voltage Vth1. When the voltage is lowered to the threshold voltage Vth2 or less, a planar state is set. 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.

When partial rewriting is performed, only specific scanning lines may be sequentially selected so as to include a portion to be rewritten. As a result, only necessary parts can be rewritten in a short time.

(Driving method 1, driving principle, see FIGS. 3 and 4)
Hereinafter, an example of a driving method applicable to the liquid crystal display element 100 will be described. First, the driving principle of the present driving method will be described. Although a specific example using an AC pulse waveform will be described here, it goes without saying that the driving method according to the present invention is not limited to this waveform. The driving method of this example is roughly divided into a reset period Tr, a selection period Ts, and a sustain period Te, as shown in FIG.
And a display period Td.

In FIG. 3, the upper part of the figure shows the driving waveform applied to the liquid crystal (LCD 1) of a certain pixel.
The lower part of the figure schematically shows the state of the liquid crystal in each period. As shown in FIG. 3, in this example, the reset period T
r is twice the selection period Ts, and the maintenance period Te is the selection period Ts.
Is set to be three times as long as.

In the reset period Tr, first, a voltage having an absolute value VR is applied to a pixel on a scanning electrode on which writing is performed, whereby the pixel on the scanning electrode is reset to a homeotropic state (see FIG. 3). a).

The selection period Ts has three more periods (a previous selection period Ts1, a selection pulse application period Ts2, and a subsequent selection period Ts).
s3). In the previous selection period Ts1, the voltage applied to the pixel on the scan electrode to be written is set to zero. At this time, the liquid crystal is slightly twisted (first
Transition state) (see b in FIG. 3). Next, a selection pulse corresponding to an image to be displayed is applied (selection pulse application period Ts2). In the selection pulse application period Ts2, a pixel that finally wants to select the planar state and a pixel that wants to select the focal conic state have the following characteristics.
The shape of the applied pulse is different. Therefore, the case where the planar state is selected and the case where the focal conic state is selected will be described separately after the selection pulse application period Ts2.

To select the planar state, a selection pulse having an absolute value Vsel is applied during the selection pulse application period Ts2, and the liquid crystal is again brought to the homeotropic state (see c1 in FIG. 3). Thereafter, when the voltage is reduced to zero in the post-selection period Ts3, the liquid crystal is in a state in which the twist is slightly restored (FIG. 3).
Middle d1). This state is considered to be substantially equal to the previous first transition state.

In the subsequent maintenance period Te, first,
A pulse voltage having an absolute value Ve is applied to a pixel on a scanning electrode to be written. The liquid crystal whose twist has slightly returned in the previous selection period Ts is untwisted again by the application of the pulse voltage Ve, and is in a homeotropic state (e in FIG. 3).
1).

In the display period Td, the voltage applied to the liquid crystal is set to zero. The liquid crystal in the homeotropic state is brought into a planar state by setting the voltage to zero (f1 in FIG. 3).
reference). In this way, the planar state is selected.

On the other hand, when it is desired to finally select the focal conic state, the voltage applied to the liquid crystal is set to zero during the selection pulse application period Ts2. As a result, a state in which the twist of the liquid crystal is further restored (second transition state) is reached (c in FIG. 3).
2). Then, during the post-selection period Ts3, the voltage applied to the liquid crystal is set to zero as in the case of selecting the planar state. By doing so, it is considered that the liquid crystal is untwisted and the helical pitch is expanded to about twice (third transition state) (see d2 in FIG. 3). This state is considered to be close to a state called a transient planar described in US Pat. No. 5,748,277.

In the subsequent sustain period Te, as in the case of selecting the planar state, a pulse voltage having an absolute value Ve is applied to the pixels on the scanning line to be written. The liquid crystal whose twist has returned in the previous selection period Ts has the pulse voltage Ve
(Fourth transition state, see e2 in FIG. 3).

In the display period Td, the voltage applied to the liquid crystal is set to zero as in the case where the planar state is selected.
Even if the voltage of the liquid crystal in the focal conic state becomes zero,
It is fixed in the focal conic state. In this way, the focal conic state is selected (f in FIG. 3).
2).

As described above, the final display state of the liquid crystal can be selected by the selection pulse applied in the short period at the center of the selection period Ts, ie, the selection pulse application period Ts2.
Further, by adjusting the pulse width of the selection pulse, specifically, by changing the shape of the pulse applied to the signal electrode according to the image data, it is possible to display a halftone.

The voltage value applied to the liquid crystal during the pre-selection period Ts1 and the post-selection period Ts3 may be a value close to zero and within a range of a voltage value at which substantially no voltage acts.

FIG. 4 shows a drive voltage waveform applied to the liquid crystal of a certain pixel among a plurality of pixels arranged in a matrix, and scanning electrodes (rows) and signal electrodes (columns) for obtaining this waveform.
An example of the waveform of FIG. In FIG. 4, a row means one line on a scanning electrode, and a column means one line on a signal electrode. The LCD means a liquid crystal layer for one pixel where a row and a column intersect.

As shown in FIG. 4, in the case of matrix driving, a predetermined voltage is applied from the signal electrode as a crosstalk voltage in order to write data to pixels on other scanning electrodes even after the elapse of the sustain period Te. . A period during which the crosstalk voltage is applied is referred to as a crosstalk period Td '.
Since the crosstalk voltage has a small pulse width and small energy, it hardly affects the state of the liquid crystal.

When the selection of all the scan electrodes is completed and the sustain period Te of the last selected scan electrode ends, all the crosstalk periods Td 'of the other scan electrodes end, and all scan electrodes and signal electrodes are connected. And the display period T
d. This state is continued until the next rewriting.

In FIG. 4, for the sake of simplicity, the reset period Tr, the selection period Ts, the sustain period Te, and the crosstalk period Td 'are all shown with the same length. Further, for the same reason, in FIG. 4, all the column signals are drawn as pulses for selecting the planar state.

(Driving Method) Hereinafter, a specific example of the matrix driving method will be described. In Examples 1 and 2 below, rows 1 to 3 mean three scanning electrodes selected in order, and columns mean one signal electrode intersecting each of the scanning electrodes. 3 to 3 mean liquid crystal layers corresponding to three pixels formed at intersections of rows 1 to 3 and columns.

(Example 1 of matrix driving, see FIG. 5) As described above, the driving method of this embodiment has a reset period, a selection period, a sustain period, and a crosstalk period. Further, the selection period is divided into three, a pre-selection period, a selection pulse application period, and a post-selection period, and the selection pulse is applied to only a part of the selection period.

It is necessary to change the shape of the selection pulse depending on the image data to be displayed on the writing target pixel, and it is necessary to apply a selection pulse having a different shape to the column according to the image data. On the other hand, in the pre-selection period and the post-selection period, since a voltage of zero is always applied to the liquid crystal in the pixel, a fixed combination of pulse waveforms can be used for both the row and the column so as to obtain the voltage of zero. In Drive Example 1 shown in FIG. 5, utilizing this, reset, maintenance, and display are simultaneously performed on pixels on a plurality of scan electrodes.

For example, when the LCD 2 is in the previous selection period, a pulse voltage + V1 having a different phase is applied to the rows 2 and 3, and a voltage of + V1 / 2 is applied to the row 1. At this time, if a pulse voltage + V1 having a phase different from that of the row 3 is applied to the column, the voltage ± VR = ±
V1 reset pulse, LCD2 voltage zero, L
A sustain pulse of voltage ± Ve = ± V1 / 2 is applied to CD1.

When the LCD 2 is in the selection pulse application period, a data pulse (voltage + V1) of a different shape is applied from the column depending on the image data, so that a pulse of voltage + V1 / 2 is applied to both row 1 and row 3. LCD
1. A voltage of ± V1 / 2 is applied to the LCD 3. A pulse of voltage + V1 is applied to row 2 and a voltage difference from the data pulse applied to the column (± V1 or zero)
Is applied to the LCD 2 as a selection pulse of the voltage ± Vsel. By changing the shape of the data pulse applied to the column, the pulse width of the selection pulse can be changed.

In the subsequent selection period, the same operation as in the previous selection period is performed. That is, a pulse voltage + V1 having a different phase is applied to rows 2 and 3, and a voltage of + V1 / 2 is applied to row 1. Then, by applying a pulse voltage + V1 having a phase different from that of the row 3 to the column, a reset pulse of a voltage ± VR = ± V1 is applied to the LCD3, a voltage of zero is applied to the LCD2, and a sustain pulse of a voltage ± Ve = ± V1 / 2 is applied to the LCD1. Apply.

During a period other than the reset period, the selection period, and the sustain period, a waveform having the same phase as the data pulse applied from the signal electrode during the pre-selection period and the post-selection period of the other scan electrodes is applied to each scan electrode. And a pulse of voltage + V1 / 2 is applied during the selection pulse application period of the other scan electrodes. Thus, a crosstalk voltage of ± V1 / 2 is applied to the liquid crystal in this portion with the same pulse width as the selection pulse in accordance with the image data. This crosstalk voltage does not affect the display state of the liquid crystal because the pulse width is narrow.

An image can be displayed by repeatedly applying the above-described pulse voltage to each scanning electrode sequentially. Selection of each scanning electrode may be performed by line-sequential scanning or interlaced scanning. Further, since the reset pulse, the selection pulse, and the sustain pulse can be applied to an arbitrary scanning electrode, partial rewriting can be performed.

In the driving example 1, the number of output voltages required for the driving IC is ternary (V1, V1 / 2, GN) on the low side.
D), the column side is binary (V1, GND). As described above, by using a row-side ternary and column-side binary driver, the cost of the driver can be reduced.

(Example 2 of matrix drive, see FIG. 6) In drive example 1, reset is performed for each scan electrode to be rewritten. In drive example 2 described here, the area to be rewritten is Is a full-reset method in which all the scanning electrodes included in the above are collectively reset. FIG. 6 shows the driving waveform. In this method, by providing a voltage switching means in the drive IC, the required number of output voltages becomes a binary value on the row side and a binary value on the column side.

First, the entire screen is reset once (initial reset). At this time, the voltage value of the reset pulse ± VR output from the drive IC is V1, but the high-voltage input voltage of all the drive ICs may be set to V1 in order to apply the reset pulse to all the screens simultaneously. Then, when scanning each scanning electrode in order, the high input voltage of the driving IC is switched to V1 / 2.

When LCD 2 is in the previous selection period, row 1
A pulse voltage + V1 / 2 having the same phase is applied to row 3 and a pulse voltage + V1 / 2 having a different phase is applied only to row 2. At this time, when a pulse voltage + V1 / 2 having the same phase as that of the row 2 is applied to the column, a zero voltage is applied to the LCD 2 and a sustain pulse of a voltage ± Ve = ± V 1/2 is applied to the LCDs 1 and 3.

When the LCD 2 is in the selection pulse application period, a pulse of a voltage + V1 / 2 is applied to all of the rows 1, 2, and 3. The voltage difference (± V2 or zero) from the data pulse applied to the column is applied to the LCD 2 as a selection pulse of the voltage ± Vsel. By changing the shape of the data pulse applied to the column, the pulse width of the selection pulse can be changed.

In the post-selection period, a pulse is applied to rows 1 to 3 and the column in the same manner as in the previous selection period.

During the periods other than the reset period, the selection period, and the sustain period, a waveform having the same phase as the data pulse applied from the signal electrode during the pre-selection period and the post-selection period is applied to each scan electrode. Is applied, a pulse of voltage + V1 / 2 is applied. Thus, a crosstalk voltage of ± V1 / 2 is applied to the liquid crystal in this portion with the same pulse width as the selection pulse in accordance with the image data. This crosstalk voltage does not affect the display state of the liquid crystal because the pulse width is narrow.

The image display can be performed by sequentially and repeatedly executing the application of the pulse voltage after the above-described initial reset to each scanning electrode. Of course, partial rewriting is also possible. In this case, initial reset and subsequent application of a pulse voltage may be performed only on the scan lines included in the rewrite target area.

In the driving example 2, the number of output voltages required for the driving IC is three in the low side (V1, V1 / 2, GND),
The column side has three values (V1, V1 / 2, GND),
The voltage V1 is required only at the time of full reset. For this reason, the voltage switching means such as an analog switch switches the voltage between the reset period and the period after that, and supplies the voltage.
D), column-side binary (V1, GND), row-side binary (V1 / 2, GND) and column-side binary (V1 / GND) when selected.
2, GND). Therefore, the cost of the driver can be further reduced.

(See Driving Method 2 and FIG. 7) In this driving method, unlike the driving examples 1 and 2, the liquid crystal on each scan electrode to be rewritten is collectively reset to the focal conic state, and then each scanning is performed. This is a driving method for sequentially selecting the liquid crystal on the electrodes into a focal conic state or a planar state.

That is, as shown in FIG. 7, the liquid crystal is reset to the focal conic state by applying a pulse voltage of the absolute value + V1 in the reset period,
Pulse voltage (absolute value V3 + V4 / 2, V
3-V4 / 2) is applied to reproduce the gradation. During the crosstalk period, a pulse voltage having an absolute value of V4 / 2 is applied.

In FIG. 7, "LCD" indicates a pulse waveform applied to the liquid crystal of one pixel. Other waveforms show examples of waveforms applied to each scanning electrode and signal electrode in order to obtain a waveform of “LCD”, and “row controller” refers to a waveform output from the controller 133 and “row VH”. Indicates a power supply voltage of the driving IC 131, and “low output” indicates a waveform output from the driving IC 131 to the liquid crystal. The “column controller” is a waveform output from the controller 134 and “column GN”.
"D" indicates a power supply voltage of the driving IC 132, and "column output" indicates a waveform output from the driving IC 132 to the liquid crystal.

(Example of matrix drive, see FIG. 8) FIG.
Shows an example of matrix driving by driving method 2. As shown in FIG. 8, first, all pixels included in the display area are collectively reset to the focal conic state, and then display is sequentially performed on each scanning line. In this driving method, although the time required for resetting is long, it is easy to reproduce a good image.

(Information Display Device and Display Example, see FIGS. 9 to 19) FIG. 9 shows a mobile phone 10 as an example of the information display device. The mobile phone 10 has the liquid crystal display element 1
A display screen 11 made of 00 is provided. The lower part of the screen 11 is an input area 12 for a user.

The input area 12 is used for inputting text data such as a telephone number and an e-mail address.
Characters such as numbers and symbols are sequentially displayed according to the operation of the operation keys. As the display mode, conventionally known various display modes can be adopted. For example, as described later, there are a mode in which characters are additionally displayed, a mode in which candidate characters are sequentially displayed at the same display position, and a mode in which kana-kanji conversion is performed.

The input area does not have to be at the lower part of the screen, and any part of the screen may be the input area. Further, there may be a plurality of input areas. Further, not only a part of the screen but also the entire surface may be an input area. Furthermore, only the input area may be independent as a separate screen, or when no character input is performed, the input area may be used as a part of the screen.

FIG. 17 shows an electronic book player 20 as another example of the information display device. The electronic book player 20 has a display screen 21 made up of the liquid crystal display element 100 on the front, and displays information recorded on a CD, an optical disk, a memory card, or the like on the screen 21. Further, a well-known touch panel is provided on the liquid crystal display element 100, and a pen, a mark, a memo, and the like can be input by the pen 22. An input area similar to that of the mobile phone 10 described above may be provided on the screen 21 of the electronic book player 20.

Hereinafter, display examples 1 to 4 in which characters are input to the input area 12 of the mobile phone 10 and display example 5 in which a horizontal line is added to the screen 21 of the electronic book player 20 will be described.

The display example 1 shown in FIG.
And can be used, for example, when inputting characters such as a mail document. First, the input area 12 is reset to the focal conic state to have a black background, and predetermined pixels of the display layers 111B, 111G, and 111R are set to the planar state to display the character "A" in white. Next, when the character “B” is added, the display layer 11
Predetermined pixels 1B, 111G, and 111R are newly set in the planar state, and the character "AB" is displayed in white.

That is, if a reset pulse is applied to the entire display area in advance to reset all the pixels included in the display area, an image displayed up to that point and an image to be newly displayed by additional writing can be added. By applying the selection pulse based on the data, additional writing can be performed without applying a reset pulse every time additional writing is performed. Note that FIG.
(A) shows a display state of each display layer corresponding to the display example 1. In each of the figures, a hatched portion indicates a selective reflection state, and a white portion indicates a transparent state.

According to the display example 1, when characters or numbers are added, the background remains black, and the already displayed information does not darken.

The background color and the image (character) color may be other colors without being limited to the display example 1, and the background color may be displayed using one or more specific display layers. An image to be additionally written may be displayed using the remaining display layers or a plurality of layers. For example, as shown in FIG. 11B, white characters may be additionally written on a blue background.

FIG. 11 schematically shows a cross section of the liquid crystal display element, and shows a display state of each display layer in the background portion and the character display portion. FIG. 11 (A) corresponds to display example 1, in which the upper part shows a state at the time of reset, the middle part shows a state when white characters are displayed in a partial area, and the lower part shows a state when white characters are additionally written. Is shown. In each display layer, a hatched portion indicates a selective reflection state, and a white portion indicates a light transmission state.

In display example 1, the colors of the background and the characters are not limited to black and white. For example, as shown in FIG. 11B, white characters can be displayed on a blue background by always setting the blue layer in the selective reflection state and displaying characters on the green and red layers. The background may be displayed on a plurality of display layers.

Display example 2 shown in FIG. 12 is an example of character conversion that can be displayed by either of the driving methods 1 and 2, and can be used, for example, when performing kana-kanji conversion and inputting kanji. First, the input area 12 is reset to make the background black (focal conic state) and the display layer 1
The predetermined pixels 11B, 111G, and 111R are set in the planar state, and the kana character “KOMATSU” is displayed in white.

Next, when converting to the kanji "Komatsu", the area 12 is reset again to make the background black (focal conic state), and predetermined pixels of the display layers 111B, 111G and 111R are set to the planar state and the kanji is set. "Komatsu" is displayed in white.

FIG. 13A shows a display state of each display layer corresponding to the display example 2. In FIG. 13 (A), the upper row shows a reset, and the lower row shows a character display, and these states are sequentially repeated during kana input and kana-kanji conversion.

According to the display example 2, the input area 12 is reset for each character conversion. However, the background remains black, and only the already displayed information darkens with a small area.

Also in the display example 2, the colors of the background and the characters are not limited to black and white. For example, as shown in FIG. By displaying characters in layers, white characters can be displayed on a blue background.

A display example 3 shown in FIG. 14 is an example in which characters or numbers that can be displayed by any of the driving methods 1 and 2 are rewritten, and can be used, for example, when selecting an input character candidate when inputting characters. First, the input area 12 is reset to set the background to black (focal conic state), set predetermined pixels of the display layers 111B, 111G, and 111R to the planar state, and display a triangular prompt and the character "?" In white.

Next, when the character “ka” is rewritten to the character “ki”, the area 12 is reset again to make the background black (focal conic state) and the display layers 111 B, 111 B
The predetermined pixels of G and 111R are set in the planar state, and the prompt and the character "" are displayed in white.

According to the display example 3, the input area 12 is reset every time character conversion is performed. However, the background remains black, and only the already displayed information darkens with a small area.

A display example 4 shown in FIG. 15 is an example in which characters or numbers that can be displayed by any of the driving methods 1 and 2 are rewritten, and the display layers 111R, 111G, and 111B are composed of fixed information and variable information. Use them properly.

First, the input area 12 is reset to set the background to black (focal conic state), and a triangle prompt as fixed information is set to a predetermined pixel of the red display layer 111R in the planar state and displayed in red. at the same time,
Characters “ka” as variable information are displayed in blue and green display layers 11
Predetermined pixels 1B and 111G are set in a planar state and displayed in blue-green.

Next, when the character "ka" is rewritten to the character "ki", the blue and green display layers 111B and 111G are driven without driving the red display layer 111R, and the background and the character "ki" are driven. Is displayed.

FIG. 16 shows a display state of each display layer corresponding to the display example 4. In FIG. 16, the upper row shows the time of reset,
The middle part shows the prompt display, and the lower part shows the character display. Character candidates to be entered are “KA”, “KI”,
Each time "ku" is selected, the middle and lower states are repeated.

According to the display example 4, even when rewriting, the background remains black, the fixed information is displayed in red and does not blink, and only the variable information darkens with a small area. Only. In addition, in the display example 4, the display layer used for displaying the fixed information and the variable information is arbitrary.

A display example 5 shown in FIG. 17 is an example in which a horizontal line is additionally written on the screen 21 of the electronic book player 20 by the driving method 2. The screen 21 is reset to the focal conic state to have a black background, and the display layer 111
It is assumed that predetermined pixels B, 111G, and 111R are set in a planar state and white is displayed as "This is a restaurant with many orders."

Here, when a touch line 22 is used to add a side line beside a "restaurant", only the red display layer 111R corresponding to the added portion is newly set to the planar state, and the "side line" is displayed in red. I do. The horizontal lines may be displayed by setting other display layers other than red in the planar state, or may be displayed in white by setting the three layers in the planar state. Furthermore, an arbitrary mark or a simple memo may be added in addition to the underline. Furthermore, as described in the display example 1, the characters and the background may be displayed in other colors.

According to this display example 5, when additional lines, characters, and the like are added, the background remains black, and the already displayed information does not darken, making it easier for the observer to see.

FIG. 18A shows a display state of each display layer corresponding to the display example 5. The upper part shows the time of reset, the middle part shows the character display, and the lower part shows the underline display.
FIG. 18B shows a display state of each display layer in a modification of the display example 5. In this modified example, characters are displayed in red, and horizontal lines are displayed in blue-green (cyan). In this case, since the additionally written portion and the already displayed portion are displayed on different display layers, for example, when erasing a horizontal line which is the additionally written portion, the display of the already displayed portion does not change and the display becomes easy to see. Further, display by the driving method 1 is also possible.

(Other Embodiments) The information display device, display method and writing method according to the present invention are not limited to the above-described embodiments, but can be variously modified within the scope of the gist.

In particular, the configuration, material, manufacturing method, drive circuit configuration, and the like of the liquid crystal display element are arbitrary. The external form of the display device, the configuration of the operation panel, and the like are also arbitrary.

The information display device may be equipped with only one driving method such as the driving methods 1 and 2 described above, or may be used by switching among a plurality of driving methods. . In particular, if a plurality of driving methods are switched and used as appropriate according to the type of input operation and display contents,
Finer display control becomes possible.

Further, as for the background color, the character color, the color of the side line, and the like, the operator can arbitrarily select them, or the background color is automatically determined for each display data by determining the background color from the display data. May be determined. In the latter case, there are a method of including data on the background color or the like in advance, and a method of analyzing the display data and determining the most frequently used color as the background.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a liquid crystal display element used for an information display device according to the present invention.

FIG. 2 is a block diagram showing a driving circuit of the liquid crystal display element.

FIG. 3 is an explanatory view showing the principle of a driving method 1 of the liquid crystal display element.

FIG. 4 is a chart showing basic driving waveforms in the driving method 1.

FIG. 5 is a chart showing driving waveforms in driving example 1.

FIG. 6 is a chart showing driving waveforms in driving example 2.

FIG. 7 is a chart showing basic driving waveforms in the liquid crystal display element driving method 2.

FIG. 8 is a chart showing driving waveforms in driving method 2.

FIG. 9 is a front view showing a mobile phone as an example of the information display device according to the present invention.

FIG. 10 is an explanatory view showing a display example 1 on the mobile phone.

FIG. 11 is an explanatory diagram showing a display state of each display layer in display example 1.

FIG. 12 is an explanatory view showing a display example 2 on the mobile phone.

FIG. 13 is an explanatory diagram showing a display state of each display layer in display example 2.

FIG. 14 is an explanatory view showing a display example 3 on the mobile phone.

FIG. 15 is an explanatory view showing a display example 4 on the mobile phone.

FIG. 16 is an explanatory diagram showing a display state of each display layer in a display example 4.

FIG. 17 is a front view showing an electronic book player as another example of the information display device according to the present invention and a display example 5 thereof.

FIG. 18 is an explanatory diagram illustrating a display state of each display layer in a display example 5.

FIG. 19 is an explanatory view showing a display example on a conventional liquid crystal display element.

[Explanation of symbols]

 10, 20 information display device 11, 21 display screen 12 input area 100 liquid crystal display element 111R, 111G, 111B display layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/46 G09G 3/20 611Z 5C060 G09G 3/20 611 621Z 5C080 621 3/36 5C094 3/36 H04N 5 / 66 102B H04N 5/66 102 G02F 1/137 505 F-term (reference) 2H088 GA03 GA17 MA20 2H089 HA32 2H093 NA61 NC14 NC90 ND01 ND42 5C006 AA22 AC24 BA11 BB08 BB12 BB28 5C058 AA07 AB03 BA04 BA01 BA04 BA01 BA18 BC01 BD02 BE05 BE10 DA10 DB03 HB01 5C080 AA10 BB05 CC03 DD01 EE01 EE30 FF10 JJ01 JJ02 JJ04 JJ05 JJ06 KK07 5C094 AA01 BA03 BA44 CA19 CA24 GA10

Claims (15)

[Claims] 1. An information display device for displaying information after resetting a previous state, comprising a display mode in which at least a part of a display area is set in advance to a color observed at the time of resetting. An information display device, characterized in that: 2. An information display device in which information is displayed after resetting a previous state, wherein a color observed at the time of reset and a color having the largest total area of the display area at the time of display are associated with each other. An information display device, comprising: a display mode for performing display. 3. The information display device according to claim 1, further comprising a display unit including a liquid crystal exhibiting a cholesteric phase. 4. The information display device according to claim 3, wherein the display section is capable of maintaining a display without applying a voltage. 5. An information display device in which at least two display layers including a liquid crystal exhibiting a cholesteric phase are stacked, wherein a background is displayed by setting a first display layer to a selective reflection state for at least a part of a display region. And a display mode for displaying information by setting the second display layer to a selective reflection state. 6. A display device according to claim 1, wherein three display layers for selectively reflecting R, G, and B lights are laminated, and at least one display layer is set to a selective reflection state for at least a part of a display area to set a background. 3. The information display device according to claim 2, further comprising a display mode for displaying and displaying information by setting at least one other display layer to a selective reflection state. 7. An information display device in which at least two display layers each including a liquid crystal exhibiting a cholesteric phase are stacked, wherein the first and second display layers are in a light-transmitting state to display a background, and the first display layer is provided. An information display device comprising: a display mode in which fixed information is displayed by setting to a selective reflection state, and variable information is displayed by setting a second display layer to a selective reflection state. 8. Three display layers for selectively reflecting R, G, and B light are laminated, and the three display layers are in a light transmitting state to display a background, and at least one display layer is selectively reflected. 8. The information display device according to claim 7, further comprising a display mode in which the display mode is set to a state where fixed information is displayed, and at least one other display layer is set to a selective reflection state to display variable information. 9. The information display device according to claim 7, wherein the fixed information and the variable information are displayed at different portions. 10. An information display device using a liquid crystal exhibiting a cholesteric phase, wherein when displaying based on text data, the liquid crystal is set to a light transmitting state to display a background, and the liquid crystal is set to a selective reflecting state. And performing a display based on the text data. 11. An information display device comprising a display unit using a liquid crystal exhibiting a cholesteric phase and information input means, wherein when performing display in accordance with information input, the liquid crystal is set in a light transmitting state in advance to set a background. And displaying the input information by setting the liquid crystal to a selective reflection state. 12. When the first display is reset from the first display and updated to the second display, a background color in the first and second displays is associated with a color observed at the time of the reset. A display method characterized by: 13. The display method according to claim 12, wherein the background color in the first and second displays is the same as the observation color at the time of reset. 14. A writing method using a display device including a display unit including a plurality of stacked display layers and input means, wherein a background is displayed on a first display layer and a second display is performed. An image corresponding to the input information is displayed on the layer. 15. The writing method according to claim 14, wherein the plurality of display layers include a layer for displaying fixed information.