JP2012177960A - Touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch panel that achieves cost reduction by reducing the number of components and man-hours for working while enhancing the measuring accuracy of coordinate point and load quantity of a load.SOLUTION: A touch panel includes a strain plate and a plurality of fixing parts provided on the strain plate, and the fixing parts are legs which can be attached to the strain plate. The touch panel also includes at least one or more strain sensors provided in such a manner that a diagonal line between the strain sensors overlaps a diagonal line between the fixing parts.

Description

  The present invention relates to a touch panel, and more particularly to a touch panel that measures a position and a load based on a contact force applied to a panel.

  The touch panel is mounted on various electronic devices, and is widely used as an input device for operating the device by pressing a display on the screen. Thus, when the operator actually touches the screen, an appropriate operation desired by the operator can be intuitively performed, which is highly convenient. Conventionally, as described in Patent Document 1, such a touch panel is obtained by holding a panel in a metal clip of a bracket at a corner of the panel and bonding the panel with an epoxy to metalize a strain gauge sensor with a solder material. The structure is brazed between the area and the bracket mounting stand. Thus, the strain gauge sensor has a structure in which a part of the mounting bracket adjacent to the metal clip is sandwiched between the glass held by the touch panel. The strain caused by the glass panel touching a specific part of its surface deflects the glass, which is then transmitted to the gauge sensor through the metal of the bracket, thereby detecting the strain.

Japanese National Patent Publication No. 10-511198

  However, since the touch panel described in Patent Document 1 is provided with new external devices at the four corners of the panel, the number of parts is large and the number of processing steps is also large, resulting in high costs. Moreover, difficulty also arises in securing a space. Furthermore, in recent years, touch panels have been applied to various fields, and the load coordinate point and the sensitivity of the load amount when touching are also required.

  Accordingly, an object of the present invention is to improve load coordinate points and load amount measurement accuracy while reducing costs by reducing the number of parts and the number of processing steps.

  In order to achieve the above object, the touch panel of the present invention has a strain generating plate and a plurality of fixing portions provided on the strain generating plate, and the fixing portion can be attached to the strain generating plate. It is a leg part and has at least 1 or more strain sensor provided in the diagonal vicinity with the said fixing | fixed part.

  According to the present invention, the measurement accuracy of load coordinate points and load amounts is improved while reducing costs by reducing the number of parts and the number of processing steps.

The side view of the touch panel which is one Example of this invention. The bottom view of the touch panel which is one Example of this invention. Sectional drawing of the touchscreen which is the other Example of this invention. The flowchart of an arithmetic processing. Model diagram when a load is applied to the touch panel. The figure which attached the strain sensor to the to-be-measured object. The figure which attached the strain sensor inclining 45 degrees. The figure showing the relationship between a sensor output and an inclination angle. Model diagram considering declination. The figure showing the relationship between the angle | corner which a load point makes, and a correction coefficient. Model diagram considering aspect ratio. The figure showing the relationship between the angle | corner which a load point makes, and correction coefficient (lambda). The model figure of the touchscreen which is the other Example of this invention. The figure showing the relationship between the angle which a load point makes, and sensor output. The figure showing the relationship between the angle which a load point makes, and sensor output ratio. Model diagram in single touch. The figure which showed the load imbalance in multiple touches. The figure which shows the touchscreen which is one Example of discrimination | determination of multiple touches. The figure which showed the gravity center position of 4 places. Model diagram of gain self-correction. The figure which showed propagation time. The figure which showed the change of the waveform by the difference in the thickness of a strain generating board. The example which applied the touch panel of this invention to the motor vehicle.

  Examples according to the present invention will be described below. In addition, the Example described below is an example to the last, and is not restricted only to this.

  1A and 1B are diagrams showing an example of the touch panel 1 of the present invention. In this embodiment, it is a configuration for use on a base such as the ground or a desk. A leg 3 (for example, rubber) is attached to the four corners of the ground contact surface of a square (or a plate having three or more corners) plate (strain plate 2), and the line and strain from the center of the leg to the center of the opposite leg. The strain sensors 4 are affixed at four locations so that the diagonal lines of the sensors 4 overlap.

  Here, it is desirable that the distance from the center of the leg 3 to the center of the strain sensor 4 is uniform, and as close as possible to the leg 3 as long as there is no interference with the strain sensor 4. At the same time, by adding excessive strain, creep of the bonded portion or failure of the strain sensor 4 itself may occur.

  Here, the strain measurement range of the strain sensor 4 is −500 με to +500 με (upper and lower limit values differ depending on the current product and the joining method), and in order to obtain sensitivity efficiently, the load range in actual use and this are generated. It is desirable that the distortion ranges match. The strain generating plate 2 is not a rigid body and has a structure in which the plate self-distortion is distorted. For this reason, by adjusting the plate thickness and material (Young's modulus) at the time of designing the strain generating plate 2, it is possible to achieve both failure reduction and sensitivity.

  FIG. 2 is an example of another touch panel 1 of the present invention. In this embodiment, it can be used even on a surface having an inclination. Holes 5 are formed in the four corners of the strain generating plate 2 by machining, and the screws 7 fixed on the base 6 side pass through the holes 5 so that they do not fall off (do not slide down). As a result, it is possible to cope until the touch panel 1 is tilted to the vertical plane.

  In order to obtain a gap corresponding to the amount of fluctuation of the strain generating plate 2, it is necessary to install a collar 8 between the base and the strain generating plate 2. The collar 8 needs to have as little influence as possible on the deformation of the strain plate 2, and the output value is stabilized by rounding the tip shape on the strain plate 2 side so as to be close to point support.

  In addition, when attaching to a surface with an angle greater than the vertical surface, it is possible to maintain a both-end support structure by sandwiching with a nut through a spring or rubber tube with a small installation area and outer diameter as much as possible, A reduction in sensitivity can be prevented as compared with the case of both-end fixed structure.

  Next, the calculation of the load coordinate point and the load amount when a load is applied to the strain generating plate 2 will be described with reference to FIGS. 3 and 4. FIG. 3 shows an example of the calculation processing flow, and FIG. 4 shows a schematic diagram of the touch panel when a load is applied. For the sake of simplicity, the strain sensor 4 is indicated by a circle.

  First, in step 100, the output voltages Vout from the four strain sensors 4 are taken into the personal computer via the AD converter (4ch).

  Next, in step 101, the load on the touch panel is eliminated (no operation), and the voltage value of each channel in this state is recorded (Vofs). Further, Vout−Vofs = Vout2 is set to eliminate the initial offset component.

  Next, in step 102, a constant load Akgf is applied from the vertical direction of the strain generating plate 2 at a point where the diagonal lines of the legs intersect (approximately the center of the plate).

  Next, in step 103, gain calibration is performed. That is, since the change ΔVout2 of Vout2 due to the load applied in step 102 corresponds to A / 4 kg, if ΔVout2 for an unknown load is Vdif, the load Wa for 1ch can be obtained as follows.

  Next, the coordinate point and load amount calculation in step 104 will be described.

  Assuming that the loads applied to the four strain sensors 4 are Wa, Wb, Wc, and Wd, the load Wall applied to the strain generating plate 2 can be obtained as follows.

  Moreover, a load coordinate point can be calculated | required with the following formula | equation.

  Here, for example, each of the strain sensors 4 received by the four strain sensors 4 when a load is applied to the load point 9 and the load received by the strain sensor 4 when a load is applied to the load point 10 respectively. The load received at 4 is different. In terms of load strain measurement characteristics, the sensor output fluctuation is more stable when the load amount is larger. Therefore, the measurement error can be further reduced by switching and using the calculation formula for obtaining the load coordinate point according to the load distribution according to the above conditions.

  Next, the correction of the load and the coordinate point in consideration of the directivity of the strain sensor 4 in step 105 will be described.

  First, the directivity of the strain sensor 4 will be described with reference to FIGS. 5 and 6. FIG. 5 is a diagram in which the strain sensor 4 is attached to the object to be measured, and a diagram in which the strain sensor 4 is attached to the object to be measured with an inclination of 45 °. FIG. 6 is a diagram showing the relationship between the sensor output when the vertical strain εX is applied and the inclination of mounting the strain sensor 4 to the object to be measured. FIG. 6 shows that the output changes at cos 2δ depending on the mounting angle. That is, for example, when the output obtained by the strain sensor shown in FIG. 5A is used as a reference, an error of about 0.06% occurs when tilted by 1 ° from the output. And if it inclines 45 degrees like FIG.5 (b), an output will be set to 0. Therefore, correction in consideration of the directivity of the strain sensor 4 is necessary.

  The deflection angle is obtained from the load coordinates obtained in step 104. Then, a correction coefficient is obtained according to FIG. 8 according to the obtained declination, and correction is performed with an error generated according to the declination.

  At this time, the corrected load is obtained by the following equation.

  As a result, the corrected Wa ′, Wb ′, Wc ′, Wd ′ obtained from the outputs of the four strain sensors in step 105 can be obtained, and the corrected load Wall ′ is again obtained in step 106 as follows. Obtained from the equation

  Next, step 107 will be described with reference to FIGS.

  When the vertical and horizontal lengths of the strain generating plate 2 are different, even when the same load amount is applied, the distortion amount differs between the long side and the short side, and it is necessary to correct the error due to this. is there.

  When the strain generating plate 2 is divided into four regions by two lines connecting the centers of the four legs 3 and plotted on the long side, the maximum is multiplied by Q / P. When plotted on the short side, P / Q is multiplied at the minimum. If the center of gravity is on the line, no correction is necessary.

  At this time, assuming that the correction coefficient is λ, the corrected load amount Wall ″ is obtained as follows. The relationship between the correction coefficient λ and the inclination angle of the load point 9 is shown in FIG.

  As described above, by performing the steps described so far, it is possible to accurately obtain the coordinate point and load amount of the load.

  Next, another example will be described with reference to FIGS. FIG. 11 is a model diagram of a touch panel according to another embodiment of the present invention, FIG. 12 is a diagram showing a relationship between an angle formed by a load point and a sensor output, and FIG. 13 is an angle formed by the load point and a sensor. It is a figure showing the relationship with an output ratio.

  In this embodiment, the description of the same parts as in the previous embodiment is omitted, and only different parts will be described. In the present embodiment, among the strain sensors 4 attached to the four corners of the strain generating plate 2, the strain sensors 4 are collected at the two corners on one side. Each of the strain sensors 4 is simply illustrated so that the attachment angle can be understood.

  As shown in FIG. 11, the attaching position of the strain sensor 4 is as close as possible, and the attaching angle difference is 45 °. Assuming that the load applied to one corner is the same, the output difference between the two strain sensors is caused by the directivity as described in step 105 of FIG. Since the relationship between “the output ratio (quotient) of the two strain sensors” and “the angle from one corner to the load point direction” is uniquely determined, the intersection position in the load point direction from the two corners becomes the load point. Here, the angles θ and η formed by the load point 9 are obtained by the following equations.

  Further, the following relationship holds from the sine theorem.

  Thus, since the distances a and b to the load point can be obtained, the load point coordinates can be obtained as follows.

  Further, the load amount W can be obtained as follows.

  As described above, in the present embodiment, the load coordinate point and the load amount can also be obtained by providing the strain sensors 4 at the two corners on one side.

  Next, another example will be described with reference to FIGS. FIG. 11 is a model diagram of a touch panel according to another embodiment of the present invention, FIG. 12 is a diagram showing a relationship between an angle formed by a load point and a sensor output, and FIG. 13 is an angle formed by the load point and a sensor. It is a figure showing the relationship with an output ratio.

  In this embodiment, the description of the same parts as in the previous embodiment is omitted, and only different parts will be described. In this embodiment, the determination can be made even when a plurality of touches are made.

  When a plurality of touches are performed, an imbalance in load distribution occurs as compared with the case of a single touch as shown in FIGS. 14 (a) and 14 (b). In other words, it is easily affected by distortion when touched at a location closer to the strain sensor 4. Also, the wider the range of multiple touches, the more imbalanced the load distribution will be with respect to a single point load.

  Hereinafter, a plurality of determination methods will be described.

  FIG. 15 shows a model diagram of multi-touch discrimination. From the following formula, the center of gravity position is calculated using the values of arbitrary three places among the load values of the four strain sensors 4, and a total of four center of gravity positions are obtained for all four patterns. The direction of multiple touches is estimated from the vector sum of the four center of gravity positions, and the four center of gravity positions are connected with straight lines as shown in FIG. Estimate the size.

  As another method, in the case of a one-point load, based on the assumption that the diagonal load total β matches the opposite diagonal load total γ, the size of the multiple touch areas is estimated from the absolute value of β-γ. The direction of multiple touches is estimated based on whether it is positive or negative.

  As another method, in the case of a one-point load, the width of multiple touch areas is estimated from the value of β / γ based on the assumption that the diagonal load total β matches the opposite diagonal load total γ. The direction of multiple touches is estimated based on whether the value is 1 or more or 1 or less.

  However, it is not possible to recognize when two points are touched on the center line, but conversely, when it is known in advance that the load is one point, it is possible to determine that there is a calibration deviation when the index for multiple touch determination becomes large. .

  Next, a further example of a plurality of touch determinations will be described. In FIG. 11, the strain sensors 4 are attached to the two corners with a shift of 45 °. However, the strain sensors 4 are attached to the four corners with a shift of 45 ° and a total of eight strain sensors 4 are attached. This makes it possible to estimate the width of the multiple touch range from the size of the range surrounded by the vector lines obtained from the four corners. In this case, even if two points are touched on the center line, it can be recognized. It becomes.

  Next, gain self-correction will be described with reference to FIGS.

  The strain sensor can also detect vibration strain. Therefore, the vibration of the strain generating plate caused by touch propagates at a constant speed (assuming sound speed) starting from the touch position, and the vibration is detected in the order closer to the touch position. At this time, since the propagation time is short, the temperature and pressure can be regarded as constant, so the propagation speed can also be regarded as constant.

  When the order of detection of vibrations by the four strain sensors 4 is A-B-C-D, the total value Tall of the times TB, TC, TD from when the vibrations are detected until A is detected. When the total of four propagation times calculated from the distance from the strain plate center to the strain sensor and the sound velocity is defined as T4, the time from the touch point to the sensor arrival is

にて求めることができる。

It can ask for.

  By substituting these time values into the formula of step 104, the touch position can be estimated. Further, by comparing with the load position calculated in step 106, it is possible to determine whether re-correction is necessary. Further, when the total load value Wall "is known in advance, the gain value can be calculated, and gain correction can be performed every time the touch is performed, the hurdle of the adhesive performance can be lowered, and the influence on the creep phenomenon can be reduced. .

  Next, a method for recognizing a waveform when a touch operation is performed according to the material and thickness of the strain-generating plate 2 will be described with reference to FIG.

  As a method for recognizing by a waveform, if the time from when the change amount of the output voltage becomes equal to or greater than a predetermined threshold to a value equal to or less than the threshold is within a predetermined range compared to when stationary, it is recognized as clicked. To do. Further, when the amount of change in the output voltage is equal to or greater than a predetermined threshold value, it is recognized that the output voltage has been slammed.

  Note that the natural frequency changes depending on the material and the plate thickness, and it is necessary to set a threshold value corresponding to the natural frequency. In the case of a hard material in particular, vibration is generated, so that recognition accuracy can be improved by performing recognition processing through “differentiation”, “Fourier transform”, “wavelet transform”, and the like.

  Next, application examples of the present invention will be described.

  In the touch panel of the present invention, the strain generating plate may be made of any material as long as it is a solid that can be bonded. For this reason, by using a conductor such as a metal plate as the strain generating plate, the strain generating plate itself can be used as an electrode. Here, if the strain generating plate and the ground are connected to the capacitance sensor and the capacitance between them is measured, an output corresponding to the distance between the human hand and the strain generating plate can be obtained. This output can be used for effects such as lighting or returning from the power saving mode after recognizing the approach.

  Moreover, when the pachinko window is used as the strain plate 2 as another application example, since the outer periphery of the window is fixed by a rigid body, both ends are fixed (not supported at both ends). In this case, since the glass corner is less likely to be distorted, the detection accuracy is improved by attaching a strain sensor near the center of each of the upper, lower, left and right sides.

  As another application example, when the strain sensor cannot be directly attached to the pachinko window, it is possible to detect the load and coordinates as a load cell by attaching the strain sensor to the pawl that holds the window from the back. Become. In this case, correction processing for sensor directivity is not necessary.

  As another application example, compression can be converted to bending by forming the leg 3 with a load cell structure. In general, the compression strain is very small due to the structural characteristics, and the sensitivity may decrease. For this reason, the detection sensitivity was improved as a structure that generates a bending force by a compressive force. At the same time, in the case of compressive strain, it is easy to be affected by the load direction and the mounting angle, but this method is not rigidly connected, but has a play to reduce these effects.

  Further, as another application example, the strain sensor 4 can be substituted on various parts mounted on an automobile and can be substituted. For example, substitute a sticker attached to the window opening / closing switch, substitute an air conditioner or audio operation switch with a seal, open / close the door to a fixed door knob (because it does not move, reduce failure), and fix the shift knob. Thus, the operation can be performed with the amount of distortion.

DESCRIPTION OF SYMBOLS 1 Touch panel 2 Strain board 3 Leg 4 Strain sensor 5 Hole 6 Base 7 Screw 8 Collar 9-10 Load point

Claims (6)

A strain plate,
A plurality of fixing portions provided on the strain plate,
The fixed portion is a leg portion that can be attached to the strain plate.
A touch panel comprising at least one strain sensor provided in the vicinity of a diagonal line with the fixed portion. A strain plate having a through hole;
A plurality of fixing portions provided on the strain plate,
The fixing portion is a fixing member that fixes the strain generating plate by being inserted into the through hole,
A touch panel, wherein at least one strain sensor is provided in the vicinity of a diagonal line with the fixed portion. The touch panel according to claim 1 or 2,
The touch panel, wherein the strain plate is substantially rectangular. The touch panel according to claim 3,
The fixing portions are provided at four corners of the strain plate,
One or more said strain sensors are each provided in four corners of the said fixing | fixed part, The touchscreen characterized by the above-mentioned. The touch panel according to claim 3,
The fixing portions are provided at four corners of the strain plate,
2. The touch panel according to claim 1, wherein two or more strain sensors are provided by being shifted by 45 degrees at two corners of a fixed portion provided on the long side of one side of the strain generating plate. The touch panel according to claim 4,
The touch panel is characterized in that two or more of the strain sensors are provided at four corners with a shift of 45 degrees.

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