JPH09138385A - Ferroelectric liquid crystal touch panel device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a depression position and make a display by one liquid crystal panel by controlling the detection of the depression position with an electromotive force, generated when a ferroelectric liquid crystal panel is pressed, and display control over the ferroelectric liquid crystal panel through a 1st and a 2nd electrode. SOLUTION: When the control signal from a control means 6 is 1, position detecting means 2a and 2b and electrodes 1a and 1b are connected. When the ferroelectric liquid crystal panel 1 is pressed, it is judged that the intersection where the largest electromotive force is obtained among intersections of electrodes 1a and 1b is the depression position. When the control signal is 0, on the other hand, display control means 3a and 3b and the electrodes 1a and 1b are connected. At this time, the electrodes 1a are applied with a select signal by the display control means 3a and other electrodes are applied with a nonselect signal. In synchronism with the select signal, the electrodes 1b apply a display signals to all the electrodes by the display control means 3b. When the control signal becomes 0, electrodes 1a other than the electrodes which are selected before are selected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric liquid crystal touch panel device.

[0002]

2. Description of the Related Art In recent years, each device tends to be large and complicated as the amount of information handled by information equipment increases and becomes complicated. Therefore, in order to make the entire device compact, a device having an input function and another function such as a display function has been considered.

As a device having such a plurality of functions, there is a panel using a liquid crystal, and the following ones are known.

The first is to detect a change in the distance between the electrodes of the panel when the display surface of the liquid crystal panel is pressed as a change in the electric capacitance, and thereby detect the pressed position of the liquid crystal panel. It constitutes a liquid crystal panel having an input function. ("11th Liquid Crystal Discussion Meeting Proceedings" (1
985) (p38 to p39)) The second one is a liquid crystal display device using the thermoelectro-optic effect, in which thermal writing is performed with a light pen consisting of a semiconductor laser and a condenser lens, and the display state is different. Is detected as a change in electric capacity, and the position at which the liquid crystal panel is thermally written is detected by this, and constitutes a liquid crystal panel having an input function. ("Proceedings of the 11th Liquid Crystal Symposium" (1985) (p42-p43))

[0005]

In the first liquid crystal panel described above, since the liquid crystal exhibits dielectric anisotropy, the capacitance changes depending on the display state of the liquid crystal (on, off, or halftone state). Therefore, it is necessary to separate the change in the capacitance when the display surface of the panel is pressed from the change in the capacitance depending on the display state. Therefore, there is a problem that the structure of the detection circuit becomes complicated and it becomes extremely difficult to separate the above-mentioned capacitors when the distance between the electrodes varies.

In the second liquid crystal panel, since the change of the writing state is detected as the change of the electric capacity, there is a problem that the input cannot be performed without changing the display state. Further, there is a problem that a special device such as a light pen is required for writing, which makes the device expensive.

As described above, conventionally, it has not been possible to obtain an effective liquid crystal panel having both an input function and other functions such as a display function.

An object of the present invention is to obtain a ferroelectric liquid crystal touch panel device which can surely perform pressing position detection and display with one liquid crystal panel.

[0009]

A ferroelectric liquid crystal touch panel device according to the present invention has a ferroelectric property in which a ferroelectric liquid crystal is sandwiched between a plurality of first electrodes and a plurality of second electrodes facing the first electrodes. A liquid crystal panel is used to detect the pressed position by electromotive force generated when the ferroelectric liquid crystal panel is pressed and display control of the ferroelectric liquid crystal is controlled through the first and second electrodes. By performing the detection operation of the pressed position at least once during one cycle of the line-sequential scanning of the first electrode, the pressed position can be surely detected regardless of the variation in cell thickness and the display state. It was done.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention relates to a ferroelectric liquid crystal panel in which a ferroelectric liquid crystal is sandwiched between a plurality of first electrodes and a plurality of second electrodes opposed to the first electrodes, and the above-mentioned ferroelectric liquid crystal panel. Detecting means for detecting the pressed position through the first and second electrodes by electromotive force generated when the liquid crystal panel is pressed, and line-sequential scanning of the first electrode and a predetermined signal to the second electrode. Is applied to the display control means for controlling the display state of the ferroelectric liquid crystal panel through the first and second electrodes, and the first and second electrodes of the position detection means and the display control means. By the selection means for selecting the connection and the position detection means at least once between the scanning of the one first electrode by the line sequential scanning and the next scanning of the one first electrode. Pressed position Composed of a control means for controlling said selection means so that the detection operation is performed.

[0011]

EXAMPLE The present invention utilizes the piezoelectric effect of a ferroelectric liquid crystal described in Japanese Patent Application No. 63-217690 already filed by the present applicant.

An embodiment of the present invention will be described below with reference to the drawings.

In this example, a single ferroelectric liquid crystal panel is used to perform, for example, key input and display.

In FIG. 1, reference numeral 1 is a ferroelectric liquid crystal panel. This has a structure as shown in FIG. That is, on the facing surfaces of the substrates 1c and 1d facing each other, IT
Transparent electrodes 1a and 1b using O or the like, alignment layers 1f and 1g using polyimide or the like are formed, and a ferroelectric liquid crystal 1e is enclosed between substrates 1c and 1d. It is preferable to use a flexible transparent body such as plastic (PET film) for the substrate 1c, and it is preferable to use a transparent body such as glass for the substrate 1d. The electrodes 1a and 1b form a matrix as shown in FIG. 1h is a seal material using an epoxy resin or the like, and 1i and 1j are polarizing plates.

The ferroelectric liquid crystal panel 1 has conditions obtained from the characteristics and the like shown in the drawings of Japanese Patent Application No. 63-217690, that is, pages 19 to 20 of the same issue.
It is preferably constructed under the conditions as described on the page. This condition is as shown below.

(1) The orientation layer has been subjected to a homogeneous orientation treatment.

(2) The orientation layers are those which have been subjected to a homogeneous orientation treatment by shifting them from parallel or antiparallel to each other.

(3) The alignment film has been subjected to a homogeneous alignment treatment by the strong rubbing method.

(4) The ferroelectric liquid crystal is a phase exhibiting ferroelectricity.

(5) The distance between the facing electrodes should be as narrow as possible.

(6) One of the alignment layers is made of a material that attracts the spontaneous polarization of the ferroelectric liquid crystal, and the other of the alignment layers is made of a material that repels the spontaneous polarization of the ferroelectric liquid crystal.

(7) Use of a ferroelectric liquid crystal having a large spontaneous polarization (8) When performing a polling treatment, the ferroelectric liquid crystal is applied at a temperature in a nematic phase or an isotropic phase. thing.

In FIG. 1, reference numerals 2a and 2b indicate the pressed positions through the electrodes 1a and 1b by the electromotive force generated between the electrodes 1a and 1b when the substrate 1c side of the ferroelectric liquid crystal panel 1 is pressed. Position detecting means. The position detecting means 2a and 2b are
It is mainly composed of an operational amplifier for voltage detection.

Display control means 3a and 3b control the display state of the ferroelectric liquid crystal panel 1 through the electrodes 1a and 1b. The display control means 3a and 3b
Is mainly composed of a drive circuit for driving the liquid crystal.

Reference numerals 5a and 5b denote the position detecting means 2a.
And 2b and the display control means 3a and 3b are connected to the electrodes 1a and 1b in a time division manner. That is, the connection of the position detection means 2a and 2b and the display control means 3a and 3b to the same electrode 1a and 1b is switched in a time division manner. The selecting means 5a and 5b are mainly composed of switching elements arranged in an array. Position detecting means 2
a and 2b are connected to the electrode 1 by the selection means 5a and 5b.
When it is connected to a and 1b, the connection of the display control means 3a and 3b to the electrodes 1a and 1b is cut off. On the contrary, the display control means 3a and 3b have the selection means 5
When the electrodes a and 5b are connected to the electrodes 1a and 1b, the position detecting means 2a and 2b are disconnected from the electrodes 1a and 1b.

Reference numeral 6 is a control means for sending a control signal to the selection means 5a and 5b.

Next, the operation of the ferroelectric liquid crystal touch panel according to each of the above components will be described.

From the control means 6, for example, a cycle of 1 msec.
A control signal for switching between "1" and "0" is sent to the selection means 5a and 5b.

When the control signal is "1", the selecting means 5a and 5b cause the position detecting means 2a and 2b.
And electrodes 1a and 1b are connected. When the ferroelectric liquid crystal panel 1 is pressed, the pressed position is detected during this period. The pressing position is the electrode 1a formed in a matrix.
Among the electromotive forces generated at the plurality of intersections 1 and 1b, the intersection having the largest electromotive force is determined as the pressing position.

On the other hand, when the control signal is "0", the display control means 3a and 3b are connected to the electrodes 1a and 1b by the selection means 5a and 5b. At this time, in the electrode 1a, one predetermined electrode is selected, the selection signal is applied by the display control means 3a, and the non-selection signal is applied to the other electrodes. In the electrode 1b, the display control means 3b applies display signals to all the electrodes in synchronization with the selection signal. Next, when the control signal becomes "0", the electrodes 1a other than the predetermined one electrode are selected. That is, for display control, the electrode 1a is set to 1 each time the control signal becomes “0”.
The electrodes are selected one by one, and line-sequential scanning is performed as in a normal liquid crystal display device.

In the above embodiment, one electrode 1a is selected each time the control signal becomes "0", but several electrodes or all electrodes are sequentially selected as the electrode 1a during the period when the control signal is "0". However, these electrodes may be continuously scanned.

Although the ferroelectric liquid crystal panel shown in FIG. 2 is premised on the display in the birefringence mode using two polarizing plates, the dichroic dye is mixed in the ferroelectric liquid crystal. It is also possible to apply a guest host mode for displaying, and at this time, one polarizing plate is enough.

FIG. 3 shows a key input device as a concrete example of use in the above embodiment.

As shown in the figure, this is to display input keys such as letters, numbers and symbols at the intersections of the electrodes 1a and 1b. In order to perform display, the electrodes 1a and 1b may be patterned into a desired shape as in the conventional liquid crystal display panel. The user may press a desired input key while observing characters, numbers, symbols, etc. displayed on the ferroelectric liquid crystal panel 1. Further, when the input key is pressed, it is more effective if the sound generation control means 4a and 4b supply a sound generation signal to the electrode corresponding to the input key to generate sound.

The input keys such as letters, numbers and symbols may be displayed at a plurality of intersections of the electrodes 1a and 1b.

Next, another embodiment of the present invention will be described.

This is to provide a sound generation control means in addition to the position detection means and the display control means in the above-mentioned embodiment, and similarly to the above-mentioned embodiment, these are sequentially connected to the electrodes by time division by the selection means. That is, in FIG. 1, the position detecting means 2a and 2b are included in the selecting means 5a and 5b.
In addition to the display control means 3a and 3b, the sound generation control means is connected. Therefore, in the following, FIG.
The description will be made assuming that the pronunciation control means is added.

FIG. 4 is a timing chart showing an example of the operation in this example.

In the same figure, during the period t1, the selection means 5a and 5b in FIG.
a and 1b are connected. And the frequency f (409
AC voltage of about 6 Hz) is applied to the electrode 1a by the sound generation control means.
And 1b, a sound is emitted from the ferroelectric liquid crystal panel due to the piezoelectric effect of the ferroelectric liquid crystal.

In the period t2 (about 62.5 msec),
The position detection means 2a and 2b and the display control means 3a and 3b are selected by the selection means 5a and 5b. The operation at this time is the same as that of the above-described embodiment.

As described above, in the example of FIG. 4, the sound is modulated at 1 / t3 Hz (about 8 Hz), and the position detection and the display control are performed during the sound generation pause period t2. The modulation is not limited to this. For example, the fundamental frequency of 4096 Hz may be modulated at 8 Hz or 256 Hz. In such a case, 256H
Position detection may be performed during the z rest period, and display control may be performed during the 8 Hz rest period.

Next, another embodiment of the present invention will be described with reference to FIG.

In the steady state, the position detecting means 2 and the electrodes 1c and 1d are connected by the selecting means 5c and 5d, but the sound generation control means 4 and the electrodes 1c and 1d are not connected. When the ferroelectric liquid crystal panel 1 is pressed and the pressed position is detected by the position detecting means 2, the states of the selecting means 5c and 5d are reversed by the output from the control means 6a. That is, the position detecting means 2 is not connected to the electrodes 1c and 1d, and the sound generation control means 4 is connected to the electrodes 1c and 1d. As a result, a predetermined sounding signal is sent from the sounding control means to the electrodes 1c and 1d, and after sounding, the steady state is restored. That is, the sound is emitted only when the ferroelectric liquid crystal panel 1 is pressed.

[0044]

According to the present invention, since the pressing position of the panel is detected by the electromotive force by using the piezoelectric effect of the ferroelectric liquid crystal, the pressing position can be reliably detected regardless of the variation in cell thickness and the display state. be able to.

Further, since the functions of position detection and display can be obtained by using the same panel, it is possible to reduce the size and thickness of the entire device.

Further, by providing the selecting means, the position detection and the display control can be individually performed, so that the respective functions can be surely operated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view of the ferroelectric liquid crystal panel in FIG.

FIG. 3 is an explanatory diagram showing a key input device using the embodiment of FIG.

FIG. 4 is a timing diagram of another embodiment of the present invention.

FIG. 5 is an explanatory diagram of another embodiment of the present invention.

[Explanation of symbols]

 1 Ferroelectric Liquid Crystal Panels 2a, 2b, 2 Position Detection Means 3a, 3b Display Control Means 4a, 4b, 4 Sound Generation Control Means 5a, 5b, 5c, 5d Selection Means

Claims (1)

[Claims] 1. A ferroelectric liquid crystal panel in which a ferroelectric liquid crystal is sandwiched between a plurality of first electrodes and a plurality of second electrodes facing the first electrodes, and the ferroelectric liquid crystal panel is pressed. Position detection means for detecting the pressed position through the first and second electrodes by electromotive force generated at times, and line-sequential scanning of the first electrode and applying a predetermined signal to the second electrode, Display control means for controlling the display state of the ferroelectric liquid crystal panel through the first and second electrodes, and selection for selecting connection of the position detection means and the display control means to the first and second electrodes Means and the operation of detecting the pressed position by the position detecting means at least one or more times between the scanning of the one first electrode by the line-sequential scanning and the scanning of the one first electrode next time. Line Ferroelectric liquid crystal touch panel device comprising a control means for controlling said selection means to divide.