KR102293761B1 - Pen pressure measurement module using semiconductor full bridge strain gauge and electronic pen applying it - Google Patents

Abstract

A pen pressure measurement module (100) of the present invention comprises: a circuit board (110) having an elastic behavior characteristic according to a pen pressure applied by a tip of an electronic pen; one semiconductor type full-bridge strain gauge (120) adhered to one side surface opposite to a surface to which the pen pressure is applied among an elastic behavior region of the circuit board (110); and a support (130) that is fixed to the circuit board (110) around the strain gauge (120) to fix or support the circuit board (110) to an inner frame of the electronic pen and the like. Therefore, the present invention is capable of accurately expressing a depth and thickness of a color.

Description

Pen pressure measurement module using semiconductor full bridge strain gauge and electronic pen applying it

The present invention relates to a pen pressure measuring module, and more particularly, by using a semiconductor-type full-bridge strain gauge to detect a resistance that changes according to the force applied to the tip of an electronic pen to precisely express the depth and thickness of color, etc. It relates to a pen pressure measuring module using a semiconductor-type full-bridge strain gauge that can be In addition, the present invention also relates to an electronic pen to which the pen pressure measurement module as described above is applied.

The electronic pen system is a new concept of pen that combines analog and digital. Like a normal pen, when you write on paper, the written contents are stored in the memory built into the pen, which is then transferred back to the computer in the form of an image file for management. This pen is designed to be Documents written with a regular pen can also be scanned with a scanner (electronic color splitter) and saved in the form of an image file, but documents written with an electronic pen do not require a scanning process, and documents can be easily managed through a separate program. advantage. The electronic pen developed in the early days could only be used by connecting it to a computer. That is, in order to use the electronic pen, the power of the computer must always be turned on, and there is also the inconvenience of using it only close to the computer. Moreover, when saving to a computer, the image file's resolution is low, making it difficult to accurately recognize the contents.

Currently, high-performance electronic pens that can be converted to digital data at any time by simply connecting to a computer by storing the written contents in the memory built into the electronic pen are also being released. Even the electronic pen itself has a built-in liquid crystal display, so you can check what you write on the screen, and a digital pen that can transmit data wirelessly without connecting to a cable is being developed, and the location of the electronic pen on the display. A touch screen method capable of detecting information or a technology capable of detecting the movement trajectory of the electronic pen by mounting an external sensor is being used.

On the other hand, it can be seen that the depth and thickness of the color expressed in the writing instrument change according to the force applied to the writing instrument. The force acting on the writing instrument is called pen pressure or pen force, and in order to give the tablet a real pen-like feel, it is necessary to measure the pen pressure function.

A type of the prior art for measuring the pen pressure of an electronic pen will be described as follows.

First, there is a pen pressure measurement method using a force sensing resistor (FSR) sensor. In a conventional device, an FSR sensor whose resistance is changed by force is used to express pen pressure. In other words, it is to use the characteristic of the FSR in which the resistance changes according to the applied force. By installing a sensor on the touch part of the electronic pen, the pen pressure can be obtained. However, this sensor is difficult to instantaneously lose the force to zero when the pen is released while applying force. That is, even in high-speed repetitive motions, if there is no pen pressure in the pen, the force must always be measured as 0, so that the pen has normal reliability.

In addition, the conventional pen pressure measuring device may have a structural problem in which the force seems to continuously increase even when a certain force is pressed. That is, the FSR sensor is difficult to be used as a high-precision force sensor due to a problem of poor creep characteristics.

Second, there is a method of measuring pen pressure using a capacitive sensor. When the distance between the two electrodes is changed, a change in capacitance (C) occurs between the two electrodes, and the change in capacitance is expressed by the following equation.

[Equation 1]

: 진공의 유전율,

: 비유전율, S: 전극 면적, d: 전극 간격이다. 이러한 원리를 이용하여 전자펜의 압력 측정부위에 정전용량센서를 채용하면, 실시간으로 변화되는 필압을 측정할 수 있다. here,

: permittivity of vacuum,

: Relative permittivity, S: electrode area, d: electrode spacing. If a capacitive sensor is employed in the pressure measuring part of the electronic pen using this principle, pen pressure that changes in real time can be measured.

This second method has a principle of measuring the pen pressure by measuring the change in the capacitance due to the change in the distance (d) between the two electrodes according to the change in force, and the change in the distance. However, in order to implement this method, an object having an elastic body must be inserted between the two electrodes and there is a prerequisite that there is no creep property. However, there is a disadvantage in that it is difficult to use or implement an elastic body having these characteristics in a method for measuring pen pressure using a capacitive sensor.

Registered Patent No. 1373203 Patent Publication No. 2013-0061958

Therefore, the present invention was developed to solve the problems of the prior art as described above, and by using a semiconductor-type full-bridge strain gauge, the resistance that changes according to the force applied to the tip of the electronic pen is sensed to increase the color depth. Its purpose is to provide a pen pressure measurement module that can accurately express the thickness and thickness of the pen.

Another object of the present invention is to provide an electronic pen to which a pen pressure measurement module using the semiconductor-type full-bridge strain gauge as described above is applied.

A pen pressure measuring module using a semiconductor full bridge strain gauge of the present invention for achieving the above object includes a circuit board having elastic behavior characteristics according to pen pressure applied by a tip of an electronic pen, and elastic behavior of the circuit board One semiconductor-type full-bridge strain gauge adhered to one surface opposite to the surface to which the pen pressure is applied in the region, and one semiconductor-type full-bridge strain gauge fixed to the circuit board around the semiconductor-type full-bridge strain gauge to attach the circuit board to the inside of the electronic pen and a fixed or supportable support, wherein the circuit board is connected to the semiconductor-type full-bridge strain gauge and has an integrated circuit having a function of driving the strain gauge and amplifying a sensing signal of the strain gauge, the semiconductor-type A full bridge strain gauge is a full bridge that forms a Wheatstone bridge in a square shape with four resistors formed by doping a silicon substrate or a silicon on insulator (SOI) substrate at a high concentration by a semiconductor process. bridge) resistance in a single chip.

In addition, according to the present invention, the circuit board has an upper and a lower surface coated with copper foil in the same manner as a general circuit board, and may be made of a flexible or rigid material.

In addition, according to the present invention, the support is preferably wrapped around the semiconductor type full bridge strain gage as a whole and fixed in a closed form, or has a form in which one side or an upper part is wrapped and fixed in an open form.

In addition, according to the present invention, it is preferable that the support wraps around the elastic behavior region of the circuit board as a whole, and has one side or the upper part open or completely closed.

In order to achieve the above object, the pen pressure measuring module using the semiconductor-type full bridge strain gauge of the present invention has elastic behavior characteristics according to the pen pressure applied by the tip of the electronic pen and can be fixed or supported inside the electronic pen. A support, one semiconductor-type full-bridge strain gauge adhered to one surface opposite to the surface to which the pen pressure is applied in the elastic behavior region of the support, and connected to the semiconductor-type full-bridge strain gauge in a state of being fixed to the support and a circuit board having an integrated circuit having a function of driving a strain gauge and amplifying a sensing signal of the strain gauge, wherein the semiconductor-type full-bridge strain gauge is a semiconductor on a silicon substrate or SOI (Silicon on Insulator) substrate. It is characterized in that four resistors formed by highly doping by a process have a full bridge resistor constituting a Wheatstone bridge in a square shape in a single chip.

In addition, according to the present invention, the support is composed of a first part having an elastic behavior characteristic and a second part having a fixed or supporting characteristic, and the first and second parts are integrated with separate materials, or the same It is preferable that the material is integrally formed.

In addition, the electronic pen of the present invention for achieving the above object is characterized in that it is configured by applying a pen pressure measuring module using a semiconductor-type full-bridge strain gauge configured as described above.

According to the present invention, by using a semiconductor-type full-bridge strain gauge, the resistance that changes according to the force applied to the tip of the electronic pen can be sensed to accurately express the depth and thickness of a color.

In addition, the present invention can be mass-produced by implementing the semiconductor-type full-bridge strain gauge in the form of a module integrated with a circuit board. In addition, since it can be applied to both flexible and rigid circuit boards, it can be applied regardless of the type of the applied electronic pen and/or the internal structure of the electronic pen.

In addition, the present invention has advantages in that miniaturization is possible, sensitivity and hysteresis characteristics are excellent, and a circuit for driving is simple by using an ultra-small semiconductor-type full-bridge strain gauge. That is, in this invention, by applying a semiconductor type full-bridge strain gauge, high precision and high reliability can be secured.

1 and 2 are a plan view and a side view of a pen pressure measuring module using a semiconductor-type full-bridge strain gauge according to an embodiment of the present invention;
3 and 4 are conceptual diagrams and real photos showing an example of the semiconductor-type full-bridge strain gauge shown in FIG. 1,
5 is a real photograph of the pen pressure measuring module shown in FIG. 1;
6 to 8 are enlarged real photos of each part of the pen pressure measuring module shown in FIG. 5,
9 and 10 are photographs and graphs showing the test process and result values for the pen pressure measuring module shown in FIG. 5;
11 is a real photograph of a printed board on which a pattern for mass production of the pen pressure measuring module shown in FIG. 5 is formed;
12 is a side view of a pen pressure measuring module using a semiconductor-type full-bridge strain gauge according to another embodiment of the present invention;
13 is a conceptual diagram of an electronic pen to which the pen pressure measuring module shown in FIG. 2 is applied;
14 is a conceptual diagram of an electronic pen to which the pen pressure measuring module shown in FIG. 12 is applied.

Hereinafter, a preferred embodiment of a pen pressure measuring module using a semiconductor-type full-bridge strain gauge according to the present invention and an electronic pen to which the same is applied will be described in detail with reference to the accompanying drawings. This invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete and to completely convey the scope of the invention to those of ordinary skill in the art. It is provided to inform you.

1 and 2 are a plan view and a side view of a pen pressure measuring module using a semiconductor-type full-bridge strain gauge according to an embodiment of the present invention. 1 and 2, the pen pressure measuring module 100 of this embodiment includes a circuit board 110 having elastic behavior characteristics according to the pen pressure applied by the tip of the electronic pen, and the circuit board 110. One semiconductor-type full-bridge strain gauge 120 (hereinafter also referred to as "strain gauge") adhered to one surface opposite to the surface to which the pen pressure is applied in the elastic behavior region, and a circuit board around the strain gauge 120 ( It is fixed to 110 and is configured to include a support 130 capable of fixing or supporting the circuit board 110 to the inner frame of the electronic pen.

The circuit board 110 has an elastic behavior (a phenomenon in which a deformed object returns to its original state) according to the applied pen pressure, and the upper and lower surfaces are coated with copper foil in the same way as a general circuit board, It can be composed of flexible or rigid materials. The circuit board 110 of this embodiment is a flexible printed circuit board (PCB), and is configured to have a hole in the center in consideration of smoother bending and/or arrangement.

In addition, the circuit board 110 is connected to the strain gauge 120 and at least a read integrated circuit 112 having a function of driving the strain gauge 120 and a function of amplifying a sensing signal of the strain gauge 120 (ROIC: readout integrated circuits). In addition, the circuit board 110 has a signal line for transmitting a signal sensed through the strain gauge 120 to the outside through the readout integrated circuit 112 .

The strain gauge 120 is adhered to one surface opposite to the surface to which the pen pressure is applied in the elastic behavior region of the circuit board 110 , and is deformed together in conjunction with the pen pressure applied to the circuit board 110 . ) is firmly (solidly, rigidly) adhered to. That is, the strain gauge 120 is bonded to the surface of the copper foil of the circuit board 110 and is deformed together when the circuit board 110 is deformed. Meanwhile, the strain gauge 120 is adhered to the surface of the circuit board 110 using an adhesive member. In this embodiment, a material having a very high hardness, such as glass frit, may be used as the adhesive member. As a high-strength adhesive member such as glass frit is used, the adhesive strength between the strain gauge 120 and the circuit board 110 is excellent, and due to the difference in the low coefficient of thermal expansion between the strain gauge 120 and the glass frit, the strain gauge ( It is possible to prevent a phenomenon in which the 120 is peeled from the circuit board 110 . In addition, due to a hard bonding method through a high-strength bonding material such as glass frit, it has excellent reliability even in high-temperature and high-humidity environments.

The strain gauge 120 of this embodiment has a full bridge resistor in which four resistors form a Wheatstone bridge in a square shape. That is, the strain gauge 120 of this embodiment is a semiconductor type, and has four resistors formed by doping a silicon substrate or a silicon on insulator (SOI) substrate at a high concentration by a semiconductor process to form a Wheatstone bridge ( It has a full bridge resistor constituting a Wheatstone bridge in a single chip.

Meanwhile, the strain gauge 120 may be classified into a film resistance strain gauge and a semiconductor strain gauge. The semiconductor-type strain gauge applied to this invention has a greater gauge factor than the film resistance-type strain gauge, so the sensitivity is 50 times greater, and the resistance value is large, so the current consumption is small and the circuit production is advantageous. In addition, semiconductor-type strain gauges have excellent temperature characteristics, and in the case of Ni and Cu alloys used as general metal-type strain gauges, the gauge factor is about 2.0 to 2.1, but the gauge factor of the semiconductor-type strain gauge is about 10 times larger than that.

Therefore, when the semiconductor strain gauge is applied to the electronic pen, it is possible to secure high precision and high reliability. In addition, it is possible to select a bonding material with excellent stress transfer as an adhesive member, and to improve yield through high integration, low hysteresis, and process simplification, miniaturization, cost reduction, and mass production.

3 and 4 are conceptual views and real photographs illustrating an example of the semiconductor type full-bridge strain gauge shown in FIG. 1 . 3 and 4, the strain gauge 120 is a piezoresistive body (R1, R2, R3) formed by highly doping a silicon substrate or a silicon on insulator (SOI) substrate by a semiconductor process. R4). Here, when the piezoresistors R1, R2, R3, and R4 are deformed by force, the resistance value increases or decreases.

For example, when tensile stress is applied, resistance increases, and when compressive stress is applied, resistance decreases. In addition, the strain gauge 120 may be a pad for connection with the conductive wire 111 including metal. The strain gauge 120 shown in FIGS. 3 and 4 is only an example, and it is natural that strain gauges of various structures can be applied to the present invention.

As shown in Figs. 3 and 4, this invention uses a strain gauge 120 of full bridge resistance having all bridge resistances in one small area, so the configuration is simplified and easily applied to products. There are advantages to doing.

1 and 2, the support 130 is fixed to the circuit board 110 around the strain gauge 120 to fix or support the circuit board 110 to the inner frame of the electronic pen, etc. As such, one end is firmly fixed to the surface of the circuit board 110 and the other end is fixed or supported on an inner frame or the like. The support 130 deforms the circuit board 110 according to the pen pressure applied to the surface of the elastic behavior region of the circuit board 110 opposite to the strain gauge 120, and the degree of deformation is measured from the strain gauge 120. It serves to fix or support the circuit board 110 to an inner frame or the like so that it can be precisely detected. Therefore, if the elastic behavior region of the circuit board 110 can be returned to its original state after being deformed by an external force in a state where it is always positioned at a fixed position, it can be fixed or supported in various structures such as being inserted into the inner frame of the electronic pen, etc. can

As described above, the support 130 determines the amount of deformation according to the pen pressure applied to the elastic behavior region of the circuit board 110 by fixing or supporting the elastic behavior region of the circuit board 110 so that it is always positioned in the correct position. ) to be accurately detected. Accordingly, one end of the support 130 is fixed to the elastic behavior region of the circuit board 110 , and is fixed in the form of wrapping around the strain gauge 120 . In this case, the strain gauge 120 may have a shape wrapped around the entire circumference and fixed in a closed shape, or wrapped around one side and/or an upper part in an open shape.

On the other hand, in this embodiment, as the support 130 is configured to cover only the circumference of the strain gauge 120 in an open U-shape, it is configured to cover only a portion of the elastic behavior region of the circuit board 110 . However, if necessary, the elastic behavior region of the circuit board 110 to which the pen pressure is applied may be entirely covered, but one side and/or the upper part may be wrapped in an open or entirely closed form. Through this, the support 130 may fix or support the entire elastic behavior region of the circuit board 110 . The support 130 may be formed of various materials, such as plastic and metal, since the circuit board 110 may be fixed or supported to the inner frame of the electronic pen.

5 is a real photo of the pen pressure measuring module shown in FIG. 1 , FIGS. 6 to 8 are enlarged real photos of a portion of the pen pressure measuring module shown in FIG. 5 , and FIGS. 9 and 10 are shown in FIG. 5 . These are photos and graphs showing the test process and result values for the pen pressure measurement module. 5 to 8, by attaching and fixing a strain gauge and a support to the surface of the flexible circuit board (with ROIC) as a base, the pen pressure measuring module according to the present invention was completed. As a result of testing this pen pressure measuring module by adding a load (corresponding to pen pressure) to the elastic behavior region of the circuit board using the equipment shown in FIG. 9, it was confirmed that there is linearity between the applied load and the output data. That is, when pen pressure is applied to the elastic behavior region of the circuit board, the resistance value sensed through the strain gauge is linearly deformed according to the magnitude of the applied pen pressure, so the force applied to the tip of the electronic pen using this signal value It is possible to accurately express the depth and thickness of the color according to the (pencil pressure).

11 is a real photograph of a printed board on which a pattern for mass production of the pen pressure measuring module shown in FIG. 5 is formed. In this invention, as shown in FIG. 11, a plurality of ROICs and strain gauges are attached and wire-bonded to the surface of a printed board on which a pattern is formed for mass production of a pen pressure measuring module using a semiconductor manufacturing process, and a plurality of pen pressures are measured by fixing each support. After the module is manufactured, it is possible to mass-produce the pen pressure measuring module in a convenient way by cutting each pen pressure measuring module individually. Here, since both flexible and rigid circuit boards can be applied as the circuit board, they are all applicable regardless of the type of the applied electronic pen and/or the internal structure of the electronic pen.

12 is a side view of a pen pressure measuring module using a semiconductor-type full-bridge strain gauge according to another embodiment of the present invention. As shown in FIG. 12 , the pen pressure measuring module 200 of this embodiment has an elastic behavior characteristic according to the pen pressure applied by the tip of the electronic pen and a support 230 that can be fixed or supported to the inner frame of the electronic pen, etc. , one semiconductor-type full-bridge strain gauge 220 (hereinafter also referred to as “strain gauge”) adhered to one surface opposite to the surface to which the pen pressure is applied among the elastic behavior region of the support 230 (hereinafter, also referred to as “strain gauge”), and the support 230 A circuit board having a readout integrated circuit 212, etc. connected to the strain gauge 220 in a state of being adhesively fixed to the readout integrated circuit having a function of driving at least the strain gauge 220 and amplifying the sensed signal of the strain gauge 220 210 is included. Reference numeral 211, not described in FIG. 12, denotes a conductive wire.

As the pen pressure measuring module 200 of this embodiment is configured to apply pen pressure to the support 230 , the support 230 is configured to have elastic behavior characteristics according to the applied pen pressure, and the elastic behavior region of the support 230 . It has the same concept as the pen pressure measurement module 100 shown in FIG. 1 except that the strain gauge 220 is adhered to one surface opposite to the surface to which the pen pressure is applied. Therefore, a detailed description of the pen pressure measuring module 200 of this embodiment will be omitted. On the other hand, in configuring the support 230 of this embodiment, the first part to which the pen pressure is applied (having elastic behavior characteristics) and the supporting second part (having supporting characteristics) are integrated with individual materials or the like, It may be configured as an integral piece of the same material, but may be configured to have elastic behavior and support characteristics at the same time.

13 is a conceptual diagram of an electronic pen to which the pen pressure measuring module shown in FIG. 2 is applied, and FIG. 14 is a conceptual diagram of an electronic pen to which the pen pressure measuring module shown in FIG. 12 is applied. 13 and 14 , the electronic pen of this embodiment is configured by applying the pen pressure measuring modules 100 and 200 as described above, and may be configured in the same concept as a general electronic pen.

The electronic pen of this embodiment is configured to be supported by a battery when fixing or supporting the supports 130 and 230 of the pen pressure measuring modules 100 and 200 to the inner frame of the electronic pen. Therefore, when a force (pencil pressure) is applied to the tip of the electronic pen as the user writes, the pen pressure is applied to the printed board 110 (Fig. 13) or the support 230 (Fig. 14) in contact with the upper end of the core material. It is applied and the strain gauges 120 and 220 sense the amount of deformation according to the applied pen pressure, so that the depth and thickness of the color can be precisely expressed.

In the above, the description of the pen pressure measuring module using the semiconductor-type full-bridge strain gauge of the present invention and the electronic pen to which the same is applied has been described along with the accompanying drawings, but this is an exemplary description of the best embodiment of the present invention. Therefore, the present invention is not limited to the above-described embodiments, and it is apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit and scope of the present invention. Examples or modifications will also fall within the scope of the claims of this invention.

100, 200: pen pressure measuring module 110, 210: circuit board
111, 211: conductive wire 112, 212: readout integrated circuit
120, 220: strain gauge 130, 230: support
R1~R4 : Piezoresistive

Claims (7)

A circuit board having elastic behavior characteristics according to the pen pressure applied by the tip of the electronic pen, and one surface opposite to the surface to which the pen pressure is applied in the elastic behavior region of the circuit board, and four resistors are whitted in a rectangular shape One semiconductor type full bridge strain gauge having a full bridge resistance constituting a Wheatstone bridge in a single chip, and fixed to the circuit board around the semiconductor type full bridge strain gauge to fix the circuit board It includes a support that can be fixed or supported inside the electronic pen,
The circuit board is connected to the semiconductor-type full-bridge strain gage and includes an integrated circuit having a function of driving the strain gage and amplifying a sensing signal of the strain gage,
The circuit board is a pen pressure measuring module using a semiconductor-type full-bridge strain gauge, characterized in that the upper and lower surfaces are coated with copper foil in the same way as a general circuit board, and it is composed of a flexible or rigid material. . delete The method according to claim 1,
The support is a pen pressure measuring module using a semiconductor full-bridge strain gauge, characterized in that it has a shape that is fixed by wrapping the entire circumference of the semiconductor-type full-bridge strain gauge in a closed form, or having one side or an upper part wrapped around an open form. . The method according to claim 1,
The support is a pen pressure measuring module using a semiconductor full-bridge strain gauge, characterized in that the entirety of the elastic behavior region of the circuit board is wrapped around, one side or the top is open or completely closed. A support that can be fixed or supported inside the electronic pen while having elastic behavior characteristics according to the pen pressure applied by the tip of the electronic pen, and one surface opposite to the surface to which the pen pressure is applied among the elastic behavior region of the support, One semiconductor-type full-bridge strain gauge having four resistors in a single chip with full-bridge resistors constituting a Wheatstone bridge in a rectangular shape, and the semiconductor-type full-bridge strain gauge in a state fixed to the support It is connected to the bridge strain gauge and includes a circuit board having an integrated circuit having a function of driving the strain gauge and amplifying a sensing signal of the strain gauge,
The support is composed of a first part having elastic behavior characteristics and a second part having fixed or supporting characteristics, and the first and second parts are integrated with individual materials or integrally formed with the same material. A pen pressure measuring module using a semiconductor-type full-bridge strain gauge. delete An electronic pen configured by applying the pen pressure measurement module using the semiconductor-type full-bridge strain gauge according to any one of claims 1 to 5.

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