KR20170026068A - Touch force sensing apparatus - Google Patents

Abstract

According to an embodiment, a plurality of electrodes for touch detection; One or more pressure sensors for touch pressure detection; And a driving circuit selectively connected to a load selected as at least one of the plurality of electrodes and one or more pressure sensors and including an operational amplifier and a compensating electrostatic capacitance connected between a first input end and an output end of the operational amplifier , A touch pressure detecting device is provided.

Description

TOUCH FORCE SENSING APPARATUS

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a touch pressure detecting device, and more particularly, to a touch pressure detecting device including a driving circuit capable of both touch detection and touch pressure detection.

BACKGROUND ART A touch panel is an input device mounted on a surface of a display to convert a physical contact of a user's finger into an electrical signal to operate the product. The touch panel can be widely applied to various display devices. In recent years, It is growing rapidly.

Such a touch panel can be classified into a resistive type, a capacitive type, an ultrasonic type (SAW), and an infrared type (IR) according to the operation principle.

Among them, the conventional capacitance type touch panel basically includes a substrate, a metal wiring layer, and a pattern layer. The pattern layer is composed of a plurality of pattern electrodes (touch patterns), and each pattern electrode generates an electrical signal corresponding to external physical contact. Then, the generated electrical signal is transmitted to the control unit of the product through the metal wires connected to the pattern electrode to operate the product.

In recent years, various types of applications having various functions in smart phones, smart TVs, and the like have emerged, so that demand for various touch methods in touch panels is increasing rapidly.

Therefore, there is a demand for a technique for judging various characteristics of the touch, specifically, the touch pressure, and performing an operation based thereon, instead of simply determining the touch position.

An object of the present invention is to make it possible to achieve the simplification of the circuit configuration by using the circuit for detecting the touch position, while enabling touch position detection and touch pressure detection.

According to an aspect of the present invention, there is provided a touch sensing apparatus including: a plurality of electrodes for touch detection; One or more pressure sensors for touch pressure detection; And a driving circuit selectively connected to a load selected as at least one of the plurality of electrodes and one or more pressure sensors and including an operational amplifier and a compensating electrostatic capacitance connected between a first input end and an output end of the operational amplifier , A touch pressure detecting device is provided.

The driving circuit comprising: a first switch connected between the rod and the ground potential; A second switch coupled between the load and a first input of the operational amplifier; A third switch connected in series between the first input terminal and the output terminal of the operational amplifier; And a fourth switch connected between the first input terminal and the output terminal of the operational amplifier.

According to the present invention, the touch position detection and the touch pressure detection can be performed, and the circuit for the conventional touch position detection can be used as it is, thereby simplifying the circuit configuration.

FIG. 1 is a view showing a configuration of a display device capable of touch pressure detection according to an embodiment of the present invention.
2 is a view showing a configuration of a pressure sensor according to an embodiment of the present invention.
3 is a circuit diagram showing a configuration of a driving circuit according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a schematic configuration of a touch pressure detecting device according to an embodiment of the present invention.

Referring to FIG. 1, a display device including a touch pressure detecting device according to an embodiment includes a glass substrate 100, a black matrix 200 formed under the glass substrate 100, And a transparent electrode layer 300 formed thereon. The transparent electrode layer 300 is provided with a plurality of electrodes for detecting a touch on the upper surface of the glass substrate 100.

At least a part of the edge of the transparent electrode layer 300 is provided with a plurality of pressure sensors 310 for sensing the pressure of the touch generated on the upper surface of the glass substrate 100.

The process of improving the display device will now be described.

First, a black matrix 200 is formed on a glass substrate 100 by a printing method or a sputtering method, and then a transparent electrode layer 300 is formed on the entire surface by a sputtering method.

Thereafter, an electrode for touch detection and an electrode pattern for pressure detection are formed in the transparent electrode layer 300 through a wet etching, a dry etching, or a laser method. The electrode pattern for pressure detection becomes a part of the pressure sensor 310. That is, a portion of the transparent electrode layer 300 functions as the first electrode 311 of the pressure sensor 310.

A piezoelectric material 312 is printed and formed on the first electrode 311 of the pressure sensor 310. A printed layer such as a carbon layer may be further formed between the black matrix 200 and the piezoelectric material 312 when necessary.

A second electrode 313 is formed on the piezoelectric material 312 so as to face the first electrode 311 and an insulating layer is formed on the piezoelectric material 312 as a protective layer 314 for protecting the internal electrodes.

FIG. 2 is a view showing the manufacturing process of the pressure sensor 310 according to one embodiment in more detail. 2, the shape of the pressure sensor 310 is circular. However, the pressure sensor 310 may have various shapes such as a circular shape or a square shape.

Referring to FIG. 2A, the first electrode 311 of the pressure sensor 310 includes a transparent electrode layer 300 (see FIG. 1) in a state where a black matrix 200 (see FIG. 1) is formed on a glass substrate 100 , See Fig. 1), or other transparent electrode material.

Referring to FIG. 2 (b), a piezoelectric material 312 is formed in an empty space of the first electrode 311 of the pressure sensor 310. The piezoelectric material 312 is formed by printing, vapor deposition, inkjet method or the like.

Referring to FIG. 2 (c), a second electrode 313 of the pressure sensor 310 is formed on the piezoelectric material 312. The second electrode 313 is made of silver (Ag), carbon (Carbon) or the like, and is formed in a lattice pattern. The second electrode 313 forms an electrical electrical failure with the first electrode 311.

Referring to FIG. 2 (d), a passivation layer 314 is formed to protect and insulate the completed pressure sensor 310.

3 is a circuit diagram showing a driving circuit of a touch pressure detecting device according to an embodiment of the present invention. 3 is selectively connected to electrodes for touch detection formed on the transparent electrode layer 300 (see FIG. 1) and electrodes for touch pressure detection and signal lines (not shown).

3, the driving circuit 400 includes an operational amplifier A, a compensating electrostatic capacitance Ccomp connected between the first input N1 and the output N2 of the operational amplifier A, And a resistor Rf that is selectively connected between the first input terminal N1 and the output terminal N2 of the operational amplifier A. [ A reference potential Vref is applied to the second input terminal of the operational amplifier A.

The rod 410 in FIG. 3 refers to an electrode for touch detection or a pressure sensor 310 (see FIG. 1) for touch pressure sensing. The driving circuit 200 includes a first switch SW1 for connecting / disconnecting the load 410 and the ground potential, a second switch SW2 for connecting / disconnecting the first input N1 of the operational amplifier A, A second switch SW2, a third switch SW3 for connecting / disconnecting one end of the resistor Rf to the first input N1 of the operational amplifier A, a first switch SW2 for connecting / disconnecting the first input N1 of the operational amplifier A, And a fourth switch SW4 connected between the output terminal N2.

First, a case where the rod 410 is an electrode for touch detection for touch detection will be described. At this time, a touch capacitance is formed between the electrode and the touch generating means (finger or the like) by a touch generated on the display device. That is, the rod 410 becomes the touch capacitance.

The charge charged in the compensation capacitance Ccomp is reset as the fourth switch SW4 is turned on and the first input terminal N1 and the output terminal N2 of the operational amplifier A become the reference potential Vref, .

Thereafter, when the fourth switch SW4 is switched to the OFF state and the second switch SW2 is switched to the ON state, a part of the charges charged in the touch capacitance as the load 410 flows into the compensation capacitance Ccomp I go in. The potential at the output terminal N2 of the operational amplifier A is changed and the potential at the output terminal N2 of the operational amplifier A is changed because the potential at the first input terminal N1 of the operational amplifier A is maintained at the reference potential Vref. The magnitude of the touch capacitance can be grasped. At the time of touch detection, the third switch SW3 always operates in the OFF state.

Next, the case where the rod 410 is a pressure sensor for touch pressure detection will be described. At this time, the resistance of the rod 410 varies depending on the pressure applied to the pressure sensor. When the same operation as that of the touch sensing operation is performed, the amount of charge flowing into the compensation capacitance Ccomp varies depending on the resistance change of the rod 410 for a specific time. Specifically, when the resistance of the rod 410 becomes large, the amount of charge flowing into the compensating capacitance Ccomp will be small. On the contrary, if the resistance of the rod 410 becomes small, the amount of charge flowing into the compensating capacitance Ccomp becomes Will grow. The resistance value of the rod 410 can be grasped by sensing the amount of charge moved during a specific time, that is, 1 / R conductance, and thus the current touch pressure can be determined.

In one embodiment, the third switch SW3 and the resistor Rf are added to accommodate a wider band and various application structures. When the driving circuit 200 is connected to the pressure sensor 310, the third switch SW3 is kept in the ON state. The resistor (Rf) can be selected and applied at various setting values like the compensation capacitance (Ccomp).

In addition, a resistance Rf can be applied to an external circuit as a fixed value in case of using a method of connecting a passive component by hardware.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (2)

A plurality of electrodes for touch detection;
One or more pressure sensors for touch pressure detection; And
And a compensating capacitance connected between a first input and an output of the operational amplifier, the compensating capacitance being selectively connected to a load selected as at least one of the plurality of electrodes and one or more pressure sensors. Touch pressure detecting device. The method according to claim 1,
Wherein the driving circuit comprises:
A first switch connected between the load and the ground potential;
A second switch coupled between the load and a first input of the operational amplifier;
A third switch connected in series between the first input terminal and the output terminal of the operational amplifier; And
And a fourth switch connected between the first input terminal and the output terminal of the operational amplifier.

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