KR102114693B1 - Force sensor and data compensation method thereof - Google Patents

Abstract

A method for calibrating data of a force sensor is disclosed. The method of calibrating the data of the present invention and the force sensor has an advantage that the detection accuracy can be maintained even after repeated pressing on the sensing unit.
In the data correction method of the force sensor of the present invention, in the data correction method of the force sensor that generates sensing data by sensing the force pressing the object, the current state is forced or unforced using the sensing data. (unforce) operation to determine the state, if the current state is a force state, the operation of setting the sensed data at the time point immediately before or immediately before the force state as offset data, and subtracting the offset data from the sensed data to correct the correction data. And calculating.

Description

Force sensor and data compensation method of force sensor {Force sensor and data compensation method thereof}

The present invention relates to a force sensor and a method for calibrating the data of the force sensor, and more specifically, a force sensor and a force sensor that corrects the sensed data to improve detection accuracy for a force sensor that senses a force pressing a sensing target. It relates to a calibration method.

In general, a smart phone, a portable electronic device such as an MP3 or a household appliance such as a refrigerator outputs various operating states, and a touch panel for input operations such as commands by a touch operation is provided. Attached.

Accordingly, the touch panel is a display device module for visually outputting information and a touch sensor module for recognizing a user's touch operation.

The display module used for such a touch panel is typically used in OLEDs (OLED, organic light emitting diode) display devices, in particular, AMOLED (active matrix organic light emitting diode) or liquid crystal display (liquid crystal display). do.

In addition, the touch sensor module uses a two-dimensional touch sensing method that detects a touch point using coordinates of the X and Y axes, as well as a three-dimensional touch sensing method that additionally senses a touch intensity applied in the Z-axis direction.

For such a three-dimensional touch sensing method, there has been a problem in that the intensity of the touch is sensed by using a pressure sensor or an image sensor, but the change in the touch intensity is not accurately detected.

Republic of Korea Registered Patent No. 10-1777733 (Registration date: September 6, 2017, title of invention: 3D touch device using image sensor and opaque member)

The problem to be solved by the present invention is to provide a force sensor with improved detection accuracy and a data correction method of the force sensor for the same.

Another problem to be solved by the present invention is to provide a force sensor capable of maintaining detection accuracy even after repeated pressing on a sensing unit and a data correction method of the force sensor therefor.

In the data correction method of the force sensor of the present invention for solving the above problems, in the data correction method of the force sensor generating sensing data by sensing the force pressing the object, force is applied to the current state ( determining a force state or an unforce state, when the current state is a force state, setting sensing data at a time point immediately before or immediately before the force state to be offset data, and offset data from the sensing data And calculating correction data by subtracting.

In one embodiment of the present invention, the force state is a state in which the pressing force is applied to a predetermined level or more, and the unforce state may be a state in which the pressing force is applied below the level or not. .

In an embodiment of the present invention, when the current state is an unforced state, the operation may further include setting the current sensed data as offset data.

In an embodiment of the present invention, when the current state is an unforced state, the operation of calculating the correction data as 0 may be further included.

In one embodiment of the present invention, the operation of determining the current state may be an operation of determining the current state using a slope value with respect to time of the detection data.

In one embodiment of the present invention, when the slope value is equal to or greater than a predetermined positive level, the current state is determined as a starting point of the force state, and when the slope value is equal to or less than a predetermined negative level, the current state is an unforced state It can be judged as the starting point.

In an embodiment of the present invention, an operation of removing noise of the correction data may be further included.

In addition, the force sensor of the present invention for solving the above problem is a force sensor that generates sensing data by sensing a force pressing a sensing target, using the sensing data to force the current state to force or unforce determining an (unforce) state, when the current state is a force state, setting the sensed data at the time when or immediately before the force state as offset data, and subtracting the offset data from the sensed data to compensate for the correction data Perform the calculation operation.

In one embodiment of the present invention, the force state is a state in which the pressing force is applied to a predetermined level or more, and the unforce state may be a state in which the pressing force is applied below the level or not. .

In an embodiment of the present invention, when the current state is an unforced state, an operation of setting the current sensed data as offset data may be further performed.

In one embodiment of the present invention, the operation of determining the current state may perform an operation of determining the current state using a slope value with respect to time of the detection data.

In one embodiment of the present invention, when the slope value is equal to or greater than a predetermined positive level, the current state is determined as a starting point of the force state, and when the slope value is equal to or less than a predetermined negative level, the current state is an unforced state It can be judged as the starting point.

The force sensor and the data calibration method of the force sensor according to an embodiment of the present invention have an advantage of improving detection accuracy.

In addition, the force sensor and the method for calibrating the data of the force sensor according to an embodiment of the present invention have an advantage that the detection accuracy can be maintained even after repeated pressing on the sensing unit.

1 is a cross-sectional view showing the configuration of a conventional force sensor.
2 is a graph showing changes over time of sensing data of a conventional force sensor.
3 is a flow chart for explaining the data correction method of the force sensor of the present invention.
4 is a graph showing a change over time of the sensing data of the force sensor and the slope value of the sensing data according to an embodiment of the present invention
5 is a graph showing changes over time of sensing data and offset data of a force sensor according to an embodiment of the present invention.
FIG. 6 is a graph showing changes over time in sensing data, offset data, and correction data of a force sensor according to an embodiment of the present invention.
7 is a graph showing changes over time of correction data and noise-removed correction data of a force sensor according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that adding a detailed description of a technology or configuration already known in the field may obscure the gist of the present invention, some of them will be omitted from the detailed description. In addition, the terms used in the present specification are terms used to properly express the embodiments of the present invention, which may vary according to persons or practices related to the field. Therefore, definitions of these terms should be made based on the contents throughout the specification.

The terminology used herein is for the purpose of referring only to specific embodiments and is not intended to limit the invention. The singular forms used herein also include plural forms unless the phrases clearly indicate the opposite. As used herein, the meaning of 'comprising' embodies certain properties, regions, integers, steps, actions, elements and / or components, and other specific properties, regions, integers, steps, actions, elements, components and / or groups It does not exclude the existence or addition of.

1 is a cross-sectional view showing the configuration of a conventional force sensor. The configuration and operation of the force sensor will be described with reference to FIG. 1.

The force sensor is a sensor that senses the force of pressing the sensing object 20. Specifically, the sensing unit L1 is located at a position spaced apart from the sensing object 20 by a predetermined distance, and when a force applied to the sensing object 20 is applied, the sensing object 20 is shaped in such a way that a force is applied. It will be transformed. At this time, the direction in which the force is applied corresponds to the direction of the sensing unit based on the sensing object 20. Therefore, the sensing object 20 is deformed so that the distance from the sensing portion L1 is close.

Here, a spacer 30 for separating the two is located between the sensing object 20 and the sensing portion L1. The spacer 30 is positioned in a part or all of the space between the sensing object 20 and the sensing unit L1.

Here, the sensing object 20 may be a touch panel. Specifically, the touch panel may be formed integrally with or combined with the display device. In some cases, the sensing object 20 may be a conductive film formed integrally with or combined with the touch panel. At this time, the conductive film may be made of a transparent conductive material such as indium tin oxide (ITO) or a conductive material such as metal.

The sensing unit L1 detects that the distance from the sensing object 20 changes and generates sensing data. The sensing unit L1 may be used in various forms capable of sensing the distance from the sensing target 20. Specifically, the sensing unit L1 may be configured to sense a change in resistance, inductance, or capacitance with the sensing object 20.

For example, when the sensing unit L1 detects a change in inductance with the sensing target 20, the sensing unit L1 may include at least one coil L1. The coil L1 may be formed on a rigid or flexible printed circuit board 10. In this case, the inductance applied to the coil L1 changes according to a change in the distance between the sensing object 20 and the coil L1. The force sensor can detect this change in inductance and generate sensing data about it.

2 is a graph showing changes over time of sensing data of a conventional force sensor. Referring to Figure 2, it will be described with respect to the problems of the conventional force sensor.

As described above, sensing the force pressed by the force sensor is due to deformation of the sensing object. When the object to be sensed is deformed by a pressing force, a predetermined recovery time is required to restore it back to its original state. However, if the force to be pressed is repeatedly applied in a state in which the recovery time has not passed, an inductance change of the force sensor may cause an error. This can cause a malfunction of sensing the pressing force.

FIG. 2 shows detection data when the force pressed against the force sensor is repeated several times at intervals. Here, a state in which the force being applied to the force sensor is applied to a predetermined level or higher is defined as a force state, and a state in which the pressing force is applied below the level or not applied at all is defined as an unforce state. Do it.

In the force state, it can be seen that the sensing data increases rapidly and the increased state is maintained. On the other hand, when changing from the force state to the unforce state, it can be seen that the sensing data does not decrease rapidly but decreases with a relatively gentle curve. The detection data will fall back to its original state if a sufficient amount of time longer than the recovery time is reached. However, as shown in the portion indicated by the Recovery Time issue in FIG. 2, when the recovery time is changed back to the force state before completely elapsed, the sensed data increases rapidly again in a state having a higher level than the initial state. Accordingly, as shown in the portion indicated by the Sensitivity issue of FIG. 2, a problem occurs in which the degree of increase in the force state is gradually increased.

When this is repeated, a change in sense data different from the change in sense data when the force is first in the initial state occurs. Specifically, the sense data immediately before the force state may be started, the amount of change in the sense data generated while being converted to the force state may be small, and the highest value of the sense data generated in the force state may be smaller. This is only an example, and various malfunctions due to the non-recovery of the object can be caused.

The present invention has been devised to solve this problem.

Hereinafter, the force sensor of the present invention and a data correction method of the force sensor will be described with reference to FIGS. 3 to 5.

3 is a flow chart for explaining the data correction method of the force sensor of the present invention.

Referring to FIG. 3, the data correction method of the force sensor of the present invention includes an operation of determining a current state (S100), an operation of setting offset data according to the current state (S200), and calculating the correction data using the offset data It includes operation S300 and operation S400 for removing noise of the correction data.

Each operation described above is preferably performed in the order described, but is not limited thereto.

Hereinafter, each step will be described in detail with reference to the accompanying drawings.

4 is a graph showing a change over time of a sensing value of a force sensor and a slope value with respect to time of the sensing data according to an embodiment of the present invention. The detection data is indicated by a solid line (black), and the slope value is indicated by a dotted line (red).

Referring to FIG. 4, an operation (S100) of determining the current state will be described. The operation of determining the current state (S100) is an operation of determining the current state as a force state or an unforce state using the sensed data.

Here, the force state means a state in which the force pressing the object to be sensed is applied to a predetermined level or higher. In addition, the unforce state means a state in which the force pressing the object to be sensed is applied below the level or not at all. At this time, the predetermined level may be adjusted in the design process, and then the user may adjust to adjust the sensitivity of the force sensor.

Specifically, the operation of determining the current state may include an operation of receiving sensing data, an operation of calculating a slope value with respect to time of the sensing data, and an operation of determining a current state using the slope value with respect to time.

The current and past detection data is received by the operation of receiving the detection data. The force sensor may calculate a slope value with respect to time using the sensed data. In addition, the current state may be determined as a force state or an unforce state by comparing a slope value with respect to a predetermined level.

Specifically, when the slope value with respect to time is equal to or higher than a predetermined positive level, the current state may be determined as the starting point of the force state. In addition, when the slope value with respect to time is equal to or less than a predetermined negative level, the current state may be determined as the starting point of the unforced state.

Referring to FIG. 4, the force sensor may determine that the force state is started at a time point when the slope value for time becomes larger than a predetermined positive level. Here, the force state may be maintained until the unforce state starts.

In some cases, the starting point of the force state may be changed to some extent. For example, it is possible to determine a time point at which the peak including the time point when the slope value for time becomes larger than a predetermined positive level is determined as the starting point of the force state. In addition, it is also possible to determine the starting point of the force state as the starting point of the predetermined time before the starting point in which the descriptive value for time becomes larger than the predetermined positive level.

In addition, the force sensor may determine that the force state starts at a time point when the slope value with respect to time becomes smaller than a predetermined negative level. Here, the force state may be maintained until the force state starts.

In some cases, the starting point of the unforced state may be changed to some extent. For example, it may be determined that the start point of the peak including the time point when the slope value for time becomes smaller than the predetermined negative level may be determined as the starting point of the unforce state. In addition, a time point before a predetermined time may be determined as a starting point of an unforce state than a time point when a slope value with respect to time is smaller than a predetermined negative level.

5 is a graph showing changes over time of sensing data and offset data of a force sensor according to an embodiment of the present invention. Detection data is indicated by a solid black line, and offset data is indicated by a solid green line.

Referring to FIG. 5, an operation (S200) of setting offset data according to the current state will be described. The operation of setting offset data according to the current state (S200) is an operation of dividing the case where the current state is in the force state and the case in the unforce state, and setting the offset data accordingly.

Hereinafter, the operation S300 of calculating the correction data using the offset data will be described again, but the offset data is the subtracted data for correction from the sensed data. Therefore, the correction data is calculated as the amount of change in the sensed data based on the offset data.

Specifically, when the current state is the force state, the sensed data at the time when the force state starts or immediately before is set as offset data. The offset data set in this way is maintained for the duration of the corresponding force state.

Accordingly, in the force state, the relative value changed based on the set offset data is calculated as the correction data. This is the amount of change in the sensed data based on the sensed data at the beginning or just before the force state, even if the sensed data is not fully recovered at the time when the force state starts or immediately before the sensed data is completely reduced. It is to judge.

Referring to FIG. 5, in the case of the first force state in which the object to be sensed enters the force state from the fully recovered state, the sensed data at the time when the first force state starts or immediately before the state is substantially zero. In this case, since the object to be sensed is completely recovered, a separate correction may not be required. In the first force state, the offset data is substantially set to zero.

On the other hand, in the case of the second and third force states that enter the force state in a state where the object to be sensed is not fully recovered, the sensed data at the time when the second and third force states start or just before the time has not yet been sufficiently reduced and is about 100 It is a corresponding state. In this case, since the object to be sensed is not fully recovered, a separate correction may be required. In the second and third force states, the offset data is set to about 100.

When the current state is an unforced state, current sensing data is set as offset data. In the case of the unforced state, the offset data may be changed according to current sensing data, not a fixed value. This means that the offset data is set to be the same as the sensing data, and the correction data is substantially calculated as zero.

Referring to FIG. 5, in the unforced state, it is illustrated that the sensing data and the offset data are set identically.

6 is a graph showing a change in time of the sensing data and the correction data of the force sensor according to an embodiment of the present invention. Detection data is indicated by a solid black line, and correction data is indicated by a solid blue line.

Referring to FIG. 6, an operation (S300) of calculating correction data using offset data will be described. The operation of calculating the correction data using the offset data (S300) is an operation of calculating the correction data by subtracting the offset data from the sensed data. Therefore, the correction data is calculated as the amount of change in the sensed data based on the offset data.

Referring to FIG. 6, in the case of the first force state in which the object to be sensed enters the force state from the fully recovered state, the sensed data at the time when the first force state starts or immediately before is the state corresponding to substantially 0, and the force state At 1, the offset data is substantially set to 0. Therefore, the correction data is calculated substantially the same as the detection data.

On the other hand, in the case of the second and third force states that enter the force state in a state where the object to be sensed is not fully recovered, the sensed data at the time when the second and third force states start or just before the time has not yet been sufficiently reduced and is about 100 In the corresponding state, the offset data is set to about 100 in the second and third force states. Therefore, the correction data is calculated to be about 100 smaller than the detection data.

In the unforced state, since the detection data and the offset data are set the same, the correction data is calculated as 0.

Referring to the correction data shown in FIG. 6, at the time when the force state starts, the correction data starts at 0 and increases, whether the object to be sensed is fully recovered or not fully recovered. Therefore, by using the correction data, it is possible to prevent malfunction due to the object being not recovered completely.

7 is a graph showing changes over time of correction data and noise-removed correction data of a force sensor according to an embodiment of the present invention. Detection data is indicated by a solid black line, correction data is indicated by a solid blue line, and correction data from which noise is removed is indicated by a solid pink line.

Referring to Fig. 7, an operation for removing noise in the correction data will be described. The operation of removing noise in the correction data is an operation of removing noise that deviates from the general trend of the correction data.

Specifically, the operation of removing noise of the correction data may be performed by smoothing the correction data of a predetermined section through a digital filter. For example, if a predetermined section is set to 10 data sections, the digital filter performs data smoothing based on the 10 correction data calculated in the past based on the current time point to remove and correct noise that deviates from the average tendency. do.

Here, in the part where the force state and the unforce state are separated, an operation for removing noise may also be performed separately. Specifically, when the force state is started, it means that the first data that is generated is not smoothed by being tied to one section of data from the unforce state before the force state.

For example, if a predetermined section is defined as 10 data sections, noise may be omitted from the first 9 data after the force state starts, and data smoothing may be performed based only on the data of the force state calculated so far. You can also do As a specific example, in the case of the sixth data calculated after the force state is started, an operation in which a separate noise is removed may not be performed and the final data may be calculated. In addition, data smoothing may be performed based only on the 1-6th data of the force state.

When an operation for removing noise is performed without such a distinction, the distinction between the force state and the unforce state may become ambiguous. Therefore, this distinction makes it possible to clarify the boundary between the force state and the unforce state.

The data calculated as the above-described operations are performed may be used as final output data. In some cases, additional data processing operations may be added during or after the above-described operations.

In the above, embodiments of the force sensor of the present invention and the data correction method of the force sensor have been described. The present invention is not limited to the above-described embodiments and the accompanying drawings, and various modifications and variations will be possible from the viewpoint of those skilled in the art to which the present invention pertains. Therefore, the scope of the present invention should be defined not only by the claims of the present specification, but also by the equivalents of the claims.

10: circuit board
20: sensing object
30: spacer
L1: Sensing part

Claims (12)

In the data correction method of the force sensor for generating a sensed data by sensing the force pressing the object,
Determining a current state as a force state or an unforce state using the sensed data;
When the current state is a force state, setting sensing data at a time point immediately before or after the force state is set as offset data; And
And calculating correction data by subtracting the offset data from the detection data,
The determining of the current state is a method of determining a current state using a slope value with respect to time of the detection data. According to claim 1,
The force state is a state in which the pressing force is applied above a predetermined level,
The unforce state is a state in which the pressing force is applied to or less than the level. According to claim 1,
And when the current state is an unforced state, setting the current sensed data as offset data. According to claim 1,
And if the current state is an unforced state, calculating the correction data as 0. delete According to claim 1,
When the slope value is equal to or higher than a predetermined positive level, the current state is determined as the starting point of the force state,
If the slope value is below a predetermined negative level, a method of determining the current state as the starting point of the unforced state. According to claim 1,
And removing noise of the correction data. In the force sensor for generating a sensed data by sensing the force pressing the object,
Determining a current state as a force state or an unforce state using the sensed data;
When the current state is a force state, setting sensing data at a time point immediately before or after the force state is set as offset data; And
Performing an operation of calculating correction data by subtracting the offset data from the detection data,
The operation of determining the current state is a force sensor performing an operation of determining the current state using a slope value with respect to time of the detection data. The method of claim 8,
The force state is a state in which the pressing force is applied above a predetermined level,
The unforce state is a force sensor in which the pressing force is applied to or below the level. The method of claim 8,
When the current state is an unforced state, the force sensor further performs an operation of setting the current sensed data as offset data. delete The method of claim 8,
When the slope value is equal to or higher than a predetermined positive level, the current state is determined as the starting point of the force state,
When the slope value is below a predetermined negative level, the force sensor determines the current state as the starting point of the unforced state.

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