TW201419064A - Foreign object detection method of a touch panel - Google Patents

Abstract

The present invention relates to a foreign object detection method of a touch panel and has steps of: receiving current sensing values output from the touch panel; comparing the current sensing values and a preset baseline to generate differences; removing the differences with low frequency by a high pass filter to keep the differences with high frequency; and determining at least one foreign object on the touch panel if the differences with high frequency exist and exceed a threshold. Therefore, when the present invention is applied in an ADC Calibration process or an object identifying process of the touch panel, the foreign object are eliminated and the real object is identified correctly.

Description

Foreign object detection method of touch panel

The present invention relates to a foreign object detecting method for a touch panel, and more particularly to a method for determining whether a touch panel has foreign matter or foreign matter information.

As shown in FIG. 7A to FIG. 7C, when the touch panel is turned on or is awakened from the sleep state, the touch panel first obtains a reference value through the analog digital conversion (ADC Calibration) (as shown in FIG. 7A). After receiving the subsequent sensing value of the touch panel (as shown in FIG. 7B), the sensing difference between the two (as shown in FIG. 7C) is taken to be preset with a sensing threshold (300; 16-carry). The comparison is performed. If the sensing threshold value is greater than the sensing threshold value, the coordinate position of the sensing difference (dV) is regarded as the coordinate position where the object exists (as indicated by the gray bottom shown in FIG. 7C), and the coordinate calculation is performed.

However, the above object recognition method still has the case of misjudgment of the object, and the following examples are illustrated:

1. If there is an object on the touch panel when the touch panel performs the analog digital conversion characteristic adjustment program, an incorrect reference value is generated, which affects the information judgment of the coordinates of the subsequent object.

Since the reference value obtained by the touch panel in the analog digital conversion characteristic adjustment program is an important basis for judging object information, the setting of the reference value is particularly important. However, if the touch panel is subjected to the analog digital conversion characteristic adjustment program, if the sensing value of the object is used as the reference value due to the presence of the object on the touch panel, the difference in the subsequent output error may be caused. And the situation of misjudgment occurs, so the user will find that the touch panel is After the device is turned on or awake, even if the user subsequently touches the touch panel with a finger or an object, the touch panel may not generate a corresponding action.

2. The situation in which the touch panel is misjudged due to changes in ambient temperature.

As shown in FIG. 8A to FIG. 8C, when the ambient temperature of the touch panel is increased, the sensing value is affected and decreased (as shown in FIG. 8B); if the foreign object detecting method is used, the reference value is As shown in FIG. 8A, the inductance difference (dV; as shown in FIG. 8C) obtained by subtracting the subtraction of the induced value due to the high temperature exceeds the sensing threshold (300; 16-bit), and exceeds the sensing. The sensing difference of the critical value is shown in the gray bottom mark shown in Fig. 8C, and it is misjudged that there is an object on the touch panel.

3. Object recognition error that causes an object sensing range to increase due to assembly defects.

If the unevenness occurs after the touch panel is installed, the panel cannot be completely flattened on the component at the unevenness to form a gap, so that the component cannot be fully supported on the back surface of the panel, and the uneven position is pressed and contacted by the single object 11. When the touch panel is bent due to an external force, the peripheral sensing value of the force receiving point of the touch panel is also reduced by deformation (as shown in FIG. 9), so that it is misjudged as A plurality of objects contact the touch panel.

Therefore, there are still many places in the touch panel for foreign object detection that need further improvement.

In view of the technical defects of the object recognition method of the touch panel, the main object of the present invention is to provide a foreign object detection method for a touch panel to help The correctness of the object recognition of the high touch panel.

The main technical means for achieving the above purpose is that the foreign object detecting method of the touch panel comprises the steps of: preset an initial reference value; receiving a sensing value of a touch panel; comparing the reference value with the sensing value, And generating a sensing difference; performing high frequency filtering on the sensing difference; and comparing the induced difference value of the completed high frequency filtering with a threshold value, and determining whether there is a foreign object according to the comparison result.

The above-mentioned invention is mainly provided with an initial reference value, so that before the touch panel performs the analog digital conversion characteristic adjustment program, it can be confirmed whether there is any foreign matter on the touch panel, that is, the sensing value currently received by the touch panel and The initial reference value is compared, and the induced difference value which can be classified as the high frequency difference is filtered by the high frequency, and the induced difference value of the high frequency filtering is compared with the critical value, and the foreign matter is correctly detected according to the comparison result. Exist, so before executing the analog digital conversion characteristic adjustment procedure, it can be determined that no foreign matter is produced to produce the correct reference value. Therefore, the present invention can accurately detect the presence or absence of foreign matter on the touch panel, and the touch panel generates the correct reference value by the analog digital conversion characteristic adjustment program.

Another main technical means for achieving the above purpose is that the foreign object detecting method of the touch panel includes: receiving an initial sensing value of a touch panel as a reference value; and receiving one of the output after receiving the touch panel Sensing the value; comparing the reference value with the sensing value, and generating an induced difference; performing high frequency filtering on the sensing difference; and The difference value of the high frequency filtering is compared with a threshold value, and the foreign matter information on the touch panel is determined according to the comparison result.

The above invention mainly utilizes high frequency filtering to extract the induced difference value which can be classified into the high frequency difference, and compares the induced difference value of the completed high frequency filtering with the critical value, and can correctly identify the position and quantity of the object according to the comparison result. .

Referring to FIG. 1 , a touch module includes a touch panel and a control circuit. The control circuit performs the foreign object detection method of the present invention, and as shown in FIG. 2A , A flow chart of a first embodiment of the method for detecting foreign matter includes: presetting an initial reference value (S10); wherein the initial reference value is obtained by sensing and analyzing the touch panel in a noise-free environment. Receiving a sensing value of a touch panel (S11); comparing the reference value with the sensing value, and generating a sensing difference (S12); as shown in FIG. 3A and FIG. 4A, respectively, the two-dimensional sensing difference is also a one-dimensional sensing value; performing high-frequency filtering on the sensing difference (S13); and comparing the induced difference value of the completed high-frequency filtering with a threshold value, and determining whether there is a foreign object according to the comparison result (S14); The new two-dimensional sensing value shown in Fig. 3B has no foreign matter, and the gray bottom shown in Fig. 4B is the position of the foreign matter, and it is judged that there is a foreign matter, which is further described in detail.

In the first embodiment, the high-frequency filtering of the inductive difference is performed by passing a high-pass filter and using each of the induced difference values as a center point of the 3×3 matrix to the adjacent sensing difference. Mutual comparison operation as real According to the sample state, if the difference value is less than a preset value after comparison, the difference value is classified as a low frequency difference value, and is filtered out; otherwise, if the difference value is greater than the preset value after comparison, the difference value is The system is classified as a high-frequency difference, and then it is retained; in Figure 3A, for example, since the difference between the sensing difference and its adjacent sensing difference is not large, the difference value after comparison is not greater than the preset value, as shown in the figure. As shown in FIG. 3B, the difference between the high-frequency filtering and the threshold value of FIG. 3B is compared with the threshold value 300. There is no difference value higher than the threshold value, which means that there is no foreign matter in the current touch panel. Therefore, although the two-dimensional sensing difference shown in FIG. 3A causes many sensing differences to exceed 300 threshold values (such as the gray bottom mark) due to the influence of the high temperature environment, the present invention performs high frequency filtering on the sensing difference. After that, the low frequency difference can be effectively filtered out, and the change of the ambient temperature is misjudged as foreign matter on the touch panel (as shown in FIG. 3B). Taking FIG. 4A as an example, since the difference between the plurality of sensing differences and the adjacent sensing difference is larger and larger than the preset value, when the high frequency filtering is performed, the sensing differences are adjacent thereto. The difference value of the sensing difference value is greater than the preset value, and is classified as a high frequency difference value, and is retained, that is, as shown in FIG. 4B, and then the sensing difference value of the high frequency filtering is completed in FIG. 4B and the If the threshold value is 300, if there is a difference value higher than the threshold value (such as the gray bottom), it means that there is a foreign object in the current touch panel.

2B is a flow chart of a second preferred embodiment of the method for detecting a foreign object according to the present invention, comprising: receiving an initial sensing value of a touch panel as a reference value (S20); wherein the initial The sensing value is the reference value generated by performing the analog digital conversion characteristic adjustment program (ADC Calibration), that is, when the touch panel performs the analog digital conversion characteristic adjustment program, it receives the touch. The initial sensing value of the control panel is used as a reference value; after receiving the touch panel, one of the sensing values is output (S21); comparing the reference value with the sensing value, and generating a sensing difference (S22); as shown in FIG. 5A a two-dimensional sensing value, which may also be a one-dimensional sensing value; performing high-frequency filtering on the sensing difference (S23); and comparing the induced difference value of the completed high-frequency filtering with a critical value, and based on the comparison result Judging the foreign matter information on the touch panel (S24); the new two-dimensional sensing value shown in FIG. 5B has a foreign object and correctly determines the position and quantity of the object, which is further described in detail.

In the second preferred embodiment, when the high-frequency filtering is performed on the sensing difference, each of the sensing differences is compared with the adjacent sensing difference, and if the difference value is less than a preset value after the comparison, the sensing difference is The value is classified as a low frequency difference and is filtered out; otherwise, if the difference value is greater than the preset value after comparison, the induced difference is classified as a high frequency difference, and is retained as shown in FIG. 5B. Then, the induced difference value of the high frequency filtering in FIG. 5B is compared with the critical value, and the same threshold value is assumed to be 300 (16-bit), and the total value of the threshold value greater than 300 is 5 (such as the gray bottom mark), and the determination is made. The high-frequency difference has exceeded the critical value, confirming that the sensing value of the currently received touch panel is foreign matter. Since the reference value of the embodiment is generated by the analog digital conversion characteristic adjustment program and is the correct reference value, the high frequency difference exceeding the critical value in FIG. 5B of the present embodiment can be used as the real data for identifying the position and quantity of the object. That is to say, FIG. 5B can be used as a two-dimensional sensing value for identifying an object, and the high-frequency difference exceeding the critical value is that the object has the correct position.

In the following, the foreign matter of the present invention will be further explained by the actual operation of the touch panel. The detection method applies the effect, but not limited to this.

When the general touch panel is turned on or is awakened from the sleep state, a reference value is first generated by the analog digital conversion characteristic adjustment program. Therefore, in order to avoid generating an incorrect reference value, the present invention sets the touch panel in advance. An initial reference value, so that the touch panel does not have to perform an analog digital conversion characteristic adjustment program when the power is turned on or is awakened from the sleep state, that is, an initial reference value has been obtained, and the initial reference value is used to determine the open opportunity or wake up on the touch panel. Whether there are foreign objects, the following are two examples.

When the touch panel is turned on or is awakened from the sleep state, the object is already on the touch panel, and the present invention receives the sensing value of FIG. 7B for foreign object determination, that is, first reads the preset initial reference value for comparison, and A two-dimensional sensing difference is generated, as shown in FIG. 4A, and then the two-dimensional sensing difference is subjected to high-frequency filtering to obtain a new two-dimensional sensing difference as shown in FIG. 4B, and assuming a critical value of 16-digit 300, The 10 sensing differences are greater than the critical value, and are considered to be foreign objects; at this time, the touch panel does not perform the analog digital conversion characteristic adjustment procedure until the analog difference values in FIG. 4B are less than the critical value, and the analog digital conversion is performed. Feature adjustment procedure to get the correct reference value.

If the touch panel is turned on or wakes up in a high temperature environment without any foreign matter such as objects on it, it will be received into the two-dimensional sensing value as shown in FIG. 8B, and the present invention also reads the preset initial reference value. And comparing the initial reference value with the two-dimensional sensing value to obtain the two-dimensional sensing difference as shown in FIG. 3A. Due to the high temperature relationship, most of the sensing differences indicated by the gray bottom exceed the critical value, but After the high frequency filtering is invented, a new two-dimensional sensing difference is obtained, as shown in FIG. 3B. Since the high temperature environment causes the sensing point of the touch panel to have no foreign matter such as objects or noise, it is obtained as shown in FIG. 3A. The sensing difference will exceed the critical value. If the abnormality exists in Figure 3A and the analog digital conversion characteristic adjustment procedure is not performed, the user will not be able to use the touch panel normally in a high temperature environment. After the frequency filtering, since the difference between the sensing differences and the value of the surrounding sensing difference is similar, most of the difference values are filtered out after the difference value is taken, and the difference values retained as shown in FIG. 3B are not exceeded. The threshold value is determined, and no foreign matter is present; therefore, the touch panel can perform an analog digital conversion characteristic adjustment program, so that the touch panel is in a high temperature environment when the device is turned on or awake, and the user can still use the device normally.

After the touch panel normally performs the analog digital conversion characteristic adjustment program, a normal reference value is generated and stored, and then the sensing value outputted by the touch panel can be subjected to object recognition. If the touch panel is touched by a single finger due to unevenness during the installation, the two-dimensional sensing value of the output is compared with the normal reference value, as shown in FIG. 5A, and the two-dimensional sensing difference is in the single object. The sensing difference of the periphery of 11 is more than the critical value, such as the gray bottom mark, but after high frequency filtering, as shown in Fig. 5B, the sensing difference exceeds the critical value due to the uneven deformation of the touch panel installation. The new sensing difference has been filtered out, and only the sensing difference of the single object 11 further exceeds the critical value and is identified as an object (as indicated by the gray bottom).

Referring to FIG. 6A, if the five-finger object touches the touch panel, the stereoscopic simulation of the sensing value output by the touch panel, as shown in the figure, the sensing value in the middle of the five-finger object is also increased, but After the high-frequency filtering, as shown in FIG. 6B, in addition to the high-frequency difference of the five-finger object sensing difference, the other sensing differences are filtered out, so that the position and quantity of the touch panel are more accurate.

In summary, the application of the present invention is performed on a touch panel to perform analog digital conversion. Confirming the presence or absence of foreign matter before changing the characteristic adjustment program can improve the accuracy of the reference value. In addition, if it is applied to the identification of the position and number of the object, the recognition rate can be improved.

10‧‧‧Touch panel

11‧‧‧ objects

20‧‧‧Control circuit

FIG. 1 is a schematic diagram of a touch module of the present invention.

2A is a flow chart showing a first preferred embodiment of the foreign matter detecting method of the present invention.

Fig. 2B is a flow chart showing a second preferred embodiment of the foreign matter detecting method of the present invention.

3A and 3B: The foreign matter detecting method of the present invention is used for two-dimensional sensing difference in a high temperature environment and two-dimensional sensing difference after high frequency filtering.

4A and 4B: The foreign object detecting method of the present invention is used for performing an analog digital conversion characteristic adjustment program, and has a two-dimensional sensing difference value of the object and a two-dimensional sensing difference value after the high frequency filtering.

5A and 5B: The foreign matter detecting method of the present invention is used for two-dimensional sensing difference due to high pressure deformation and two-dimensional sensing difference after high frequency filtering.

6A and 6B are diagrams showing the induced difference energy simulation diagram of the five-finger object recognition method and the induction number energy simulation diagram after the high-frequency filtering.

7A to 7C are two-dimensional reference values, two-dimensional sensing values, and two-dimensional sensing differences of an object when the touch panel performs the analog digital conversion characteristic adjustment program.

8A to 8C are two-dimensional reference values, two-dimensional sensing values, and two-dimensional sensing differences of a touch panel for use in a high temperature environment.

Figure 9: There are two touch panels for the two-dimensional sensing difference due to high pressure deformation.

Claims (10)

A foreign object detecting method for a touch panel includes: presetting an initial reference value; receiving a sensing value of a touch panel; comparing the initial reference value with the sensing value, and generating an sensing difference; Performing high frequency filtering; and comparing the induced difference value of the completed high frequency filtering with a critical value, and judging whether there is a foreign object according to the comparison result. The foreign object detecting method according to claim 1, wherein in the step of performing high frequency filtering on the induced difference value, each of the sensing difference values is compared with an adjacent sensing difference value to obtain a difference value. The method for detecting a foreign object according to claim 2, wherein in the step of performing high frequency filtering on the inductive difference, the difference value is higher than a preset value, and is a high frequency difference and is reserved, and is lower than the frequency. At the preset value of the frequency, the low frequency difference is filtered out. The method for detecting a foreign object according to claim 1 or 2, wherein the preset reference value is obtained by sensing and analyzing the touch panel in a noise-free environment. The method for detecting a foreign object according to claim 3, wherein the preset reference value is obtained by sensing and analyzing the touch panel in a noise-free environment. A method for detecting a foreign object of a touch panel includes: receiving an initial sensing value of a touch panel as a reference value; receiving an inductive value after receiving the touch panel; comparing the reference value with the sensing value, and Generating a sensing difference; performing high frequency filtering on the sensing difference; and comparing the induced difference value of the completed high frequency filtering with a threshold value, and The foreign matter information on the touch panel is judged according to the comparison result. The foreign object detecting method according to claim 6, wherein the initial sensing value is generated by an analog-to-digital conversion characteristic adjusting program. The method for detecting foreign matter according to claim 6 or 7, wherein in the step of performing high frequency filtering on the induced difference value, comparing each of the induced difference values with the adjacent induced difference value to obtain a difference value. The method for detecting a foreign object according to claim 6 or 7, wherein in the step of performing high frequency filtering on the inductive difference, the difference value is higher than a preset value, which is a high frequency difference and is reserved, and is low. When the frequency is preset to the frequency, the low frequency difference is filtered out. The method for detecting foreign matter according to claim 8, wherein in the step of performing high frequency filtering on the inductive difference, the difference value is higher than a preset value, and is a high frequency difference and is reserved, and is lower than the frequency. At the preset value of the frequency, the low frequency difference is filtered out.