Capacitive touch device and operating method thereof

Abstract

The present invention discloses a capacitive touch device and an operating method thereof. The capacitive touch device is coupled between a first conductor and a microcontroller, and includes a capacitance detection circuit and a touch value comparator. The capacitance detection circuit is used to detect the capacitance change of a first sensing capacitor in a first touch key mode to generate a first touch value related to the first conductor. The touch value comparator determines whether to generate an interrupt signal to the microcontroller based on the first touch value to instruct the microcontroller to read the first touch value, thereby improving the power consumption of the microcontroller.

Description

Technical Field

[0001] The present invention relates to a capacitive touch device and an operating method thereof, and more particularly to a capacitive touch device and an operating method thereof that can be integrated into a single chip and improve the power consumption of a microcontroller. Background Art

[0002] Capacitive touch has become a necessary function of today's products, and capacitive touch devices use a capacitive detection circuit to detect the finger capacitance formed between the conductor (e.g., copper sheet) used as a button and the user's finger. For example, see Figure 1 , Figure 1 1 is a schematic diagram of a conventional capacitive touch device. The capacitive touch device 1 can be implemented by a single chip, and includes a capacitance detection circuit 10. The capacitance detection circuit 10 is coupled to a microcontroller ( Figure 1 Not shown) and at least one conductor used to implement a key, and an external storage capacitor Cs. For the convenience of the following description, Figure 1 The capacitance detection circuit 10 only adopts an example of coupling one conductor 12 , and the capacitance detection circuit 10 includes a switch SW1 , a switch SW2 , a switch SW3 and a voltage detector 101 .

[0003] Specifically, the capacitance detection circuit 10 is coupled to the conductor 12 via a node A, and the switch SW1 is coupled between the node A and the storage capacitor Cs. The switch SW2 is coupled between the node A and the power supply voltage VDD, and the switch SW3 is coupled between the ground voltage GND and the storage capacitor Cs. The switch SW3 and the switch SW1 are coupled to the first end of the storage capacitor Cs via a node B, and the second end of the storage capacitor Cs is coupled to the ground voltage GND. In addition, the voltage detector 101 is implemented by a comparator CP, and the non-inverting input terminal of the comparator CP is also coupled to the node B, and the inverting input terminal receives the reference voltage Vref.

[0004] like Figure 1 As shown, in addition to the finger capacitance Cf, the sensing capacitance outside the chip also has a parasitic capacitance Cd mainly from the printed circuit board (PCB), and the operation method of the capacitance detection circuit 10 is to first turn on the switch SW3, so as to provide a discharge path to discharge the voltage Vcs of the storage capacitor Cs to the ground voltage GND of zero. Secondly, turn off the switch SW3 and turn on the switch SW2, so as to provide a charging path to charge the voltage Vdf of the parasitic capacitance Cd and the finger capacitance Cf to the power supply voltage VDD.

[0005] Next, the switch SW2 is turned off and the switch SW1 is turned on, so that a charge transfer path is provided to transfer the charge stored in the parasitic capacitor Cd and the finger capacitor Cf to the storage capacitor Cs, and the parasitic capacitor Cd and the finger capacitor Cf are repeatedly charged and the charge stored therein is transferred to the storage capacitor Cs, or the switch SW2 and the switch SW1 are turned on cyclically until the voltage Vcs of the storage capacitor Cs reaches the reference voltage Vref. In this process, if the parasitic capacitor Cd and the finger capacitor Cf are larger, the more charge is transferred to the storage capacitor Cs each time the switch SW1 is turned on, and the number of cycles of turning on the switch SW2 and the switch SW1 is reduced.

[0006] However, because the finger capacitance Cf is zero when the finger 11 does not press the conductor 12, but is about 0.5 pF when the finger 11 presses the conductor 12, the microcontroller can determine whether the finger 11 presses the conductor 12 according to the number of cycles of turning on the switch SW2 and the switch SW1. In other words, the larger the capacitance value of the parasitic capacitance Cd, the smaller the capacitance change of the finger capacitance Cf that can be detected by the capacitance detection circuit 10. In addition, as the position of each touch button (i.e., each conductor) is different, the PCB routing method and length are also different, and the routing is easily affected by the ground terminal, so that the capacitance value of the parasitic capacitance Cd is inconsistent on each touch button, so the PCB design on the capacitive touch device 1 becomes very difficult.

[0007] On the other hand, because the storage capacitor Cs is usually greater than 3000pF, it cannot be integrated with the capacitance detection circuit 10 in a single chip. In addition, in addition to the comparator CP used to compare the voltage Vcs and the reference voltage Vref, it is difficult to achieve high resolution. The storage capacitor Cs is also easily affected by changes in ambient temperature and humidity due to its external connection, resulting in misjudgment of the detection. Capacitive touch buttons are also easily interfered by external signals, such as radio frequency interference, radiation interference, and power supply noise interference. In addition, if the microcontroller is in the state of judging the finger pressing the key for a longer time, its power consumption will be relatively more. Therefore, how to design a capacitive touch device that can be integrated into a single chip and improve the power consumption of the microcontroller has become an important issue in this field. Summary of the invention

[0008] In view of this, an embodiment of the present invention provides a capacitive touch device, which is coupled between a first conductor and a microcontroller, and includes a capacitance detection circuit and a touch value comparator. The capacitance detection circuit is coupled to the first conductor and the microcontroller, and is used to detect the capacitance change of the first sensing capacitor in the first touch key mode to generate a first touch value related to the first conductor. The touch value comparator is coupled to the capacitance detection circuit and the microcontroller, and determines whether to generate an interrupt signal to the microcontroller according to the first touch value to instruct the microcontroller to read the first touch value.

[0009] In addition, an embodiment of the present invention further provides an operating method for a capacitive touch device. The capacitive touch device includes a capacitance detection circuit and a touch value comparator, the capacitance detection circuit is coupled to a first conductor and a microcontroller, and the operating method includes the following steps. The capacitance detection circuit detects a change in the capacitance value of a first sensing capacitor in a first touch key mode to generate a first touch value related to the first conductor. Then, based on the first touch value, the touch value comparator determines whether to generate an interrupt signal to the microcontroller to instruct the microcontroller to read the first touch value.

[0010] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of a conventional capacitive touch device.

[0012] Figure 2 is a schematic diagram of a capacitive touch device provided by an embodiment of the present invention.

[0013] Figure 3 It is a flowchart of the steps of the operating method provided by an embodiment of the present invention.

[0014] Figure 4 yes Figure 2 A flow chart of the steps of the operation method of the capacitance detection circuit in the capacitive touch device in the first adaptive capacitance mode and the first touch key mode. DETAILED DESCRIPTION

[0015] The following is an explanation of the implementation of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the content provided in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. In addition, the drawings of the present invention are only simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following implementations will further explain the relevant technical content of the present invention in detail, but the content provided is not intended to limit the scope of protection of the present invention.

[0016] It should be understood that, although the terms "first", "second", "third", etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0017] See also Figure 2 , Figure 2 2 is a schematic diagram of a capacitive touch device provided by an embodiment of the present invention. The capacitive touch device 2 can also be implemented by a single chip, and is coupled to a microcontroller 4 and at least one conductor ( Figure 2 The capacitive touch device 2 includes a capacitance detection circuit 20 and a touch value comparator 22. The capacitance detection circuit 20 is coupled to the microcontroller 4 and the at least one conductor. For the convenience of the following description, Figure 2 The capacitance detection circuit 20 of the embodiment also only uses an example of coupling one conductor, namely the first conductor, but is different from Figure 1 The capacitance detection circuit 10 includes a storage capacitor Cs2 and a variable capacitor Cr connected in parallel, and also includes a charge transfer structure composed of five switches SW1a, SW1b, SW2a, SW2b, and SW3a. In this embodiment, the capacitance detection circuit 20 is coupled to the first conductor through the pin P1, and the switch SW1b is coupled between the node C and the storage capacitor Cs2, and the node C is located between the pin P1 and the switch SW1b.

[0018] In addition, the switch SW2a is coupled between the node C and the first power supply voltage Va, the switch SW3a is coupled between the second power supply voltage Vb and the storage capacitor Cs2, and the switch SW3a and the switch SW1b are coupled to the first end of the storage capacitor Cs2 through the node D, and the second end of the storage capacitor Cs2 is coupled to the ground voltage GND. Finally, the switch SW2b is coupled between the node D and the variable capacitor Cr, the switch SW1a is coupled between the ground voltage GND and the variable capacitor Cr, and the switch SW1a and the switch SW2b are coupled to the first end of the variable capacitor Cr through the node E, and the second end of the variable capacitor Cr is also coupled to the ground voltage GND. In other words, the capacitance detection circuit 20 may also include a circuit for generating a plurality of control signals ( Figure 2 (not shown) to control the path selection circuit (not shown) of the five switches SW1a, SW1b, SW2a, SW2b, and SW3a to be turned on or off respectively. Figure 2 However, the present invention does not limit the specific implementation of the path selection circuit, so the details thereof will not be described in detail here.

[0019] It should be noted that, compared to the operation method of the capacitance detection circuit 10, the capacitance detection circuit 20 is used to adjust the capacitance value of the variable capacitor Cr in the first adaptive capacitance mode, and detect the capacitance value change of the first sensing capacitor (Cd1+Cf1) in the first touch key mode to generate a first touch value ( Figure 2 Therefore, if Figure 2 As shown, in the first adaptive capacitance mode, the capacitance detection circuit 20 first turns on the switch SW2a and the switch SW3a at the same time, so as to provide a first charging path to charge the voltage Vdf of the first sensing capacitor (Cd1+Cf1) to the first power supply voltage Va, and provide a second charging path to charge the voltage Vcs2 of the storage capacitor Cs2 to the second power supply voltage Vb, and then turns off the switch SW2a and the switch SW3a at the same time.

[0020] As mentioned above, since the first sensing capacitor outside the chip has a first parasitic capacitor Cd1 mainly from the PCB in addition to the first finger capacitor Cf1, the first sensing capacitor can be simplified as (Cd1+Cf1) in this embodiment. In addition, the second power supply voltage Vb is less than the first power supply voltage Va, and the capacitance detection circuit 20 can also include an internal regulator 205 for generating the first power supply voltage Va and the second power supply voltage Vb, but the present invention does not limit the specific implementation of the internal regulator 205, so the details thereof will not be repeated here. In summary, this embodiment can assume that the first power supply voltage Va is 2 volts and the second power supply voltage Vb is 1 volt (i.e., Vb=Va / 2).

[0021] Secondly, the capacitance detection circuit 20 will turn on the switch SW1a and the switch SW1b at the same time, so that a discharge path is provided to discharge the voltage of the variable capacitor Cr to the ground voltage GND, and a first charge transfer path is provided to transfer the charge stored in the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2, and then the switch SW1a and the switch SW1b are turned off at the same time. Next, the capacitance detection circuit 20 will turn on the switch SW2a and the switch SW2b at the same time, so that a first charging path is provided to charge the voltage Vdf of the first sensing capacitor (Cd1+Cf1) to the first power supply voltage Va, and a second charge transfer path is provided to transfer the charge stored in the storage capacitor Cs2 to the variable capacitor Cr, and then the switch SW2a and the switch SW2b are turned off at the same time, and the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr is compared with the second power supply voltage Vb, and the capacitance value of the variable capacitor Cr is adjusted according to the comparison result.

[0022] For example, if the voltage Vcs2 at this time is greater than the second power supply voltage Vb, it means that the capacitance value of the variable capacitor Cr is too small, so the capacitance detection circuit 20 can increase the capacitance value of the variable capacitor Cr through a variable capacitor controller 207; conversely, if the voltage Vcs2 at this time is less than the second power supply voltage Vb, it means that the capacitance value of the variable capacitor Cr is too large, so the capacitance detection circuit 20 can decrease the capacitance value of the variable capacitor Cr through the variable capacitor controller 207, but the present invention does not limit the specific implementation method of the variable capacitor controller 207, so the details thereof will not be repeated here. It should be noted that the capacitance detection circuit 20 can repeatedly provide the discharge path plus the first charge transfer path and the first charging path plus the second charge transfer path of the variable capacitor Cr, or cyclically turn on the switches SW1a plus SW1b and the switches SW2a plus SW2b, until the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr is equal to the second power supply voltage Vb, or the voltage Vcs2 and the second power supply voltage Vb approach to be consistent, and the capacitance detection circuit 20 completes the first adaptive capacitance mode.

[0023] In other words, the purpose of the first adaptive capacitance mode is to adjust the capacitance value of the variable capacitor Cr to be equal to or close to the capacitance value of the current first sensing capacitor (Cd1+Cf1). In addition, it should be understood that the storage capacitor Cs2 is charged by the first sensing capacitor (Cd1+Cf1), and the variable capacitor Cr is discharged by it. Therefore, in this embodiment, the storage capacitor Cs2 only needs to be designed to be approximately 200pF, so that it and the capacitance detection circuit 20 can be integrated into a single chip. In this way, the capacitance detection circuit 20 does not require an external capacitor component, so that it can avoid the misjudgment of the detection caused by changes in ambient temperature and humidity. Relatively speaking, a small capacitor of about 200pF built in does not attenuate the change in the touch value, but can achieve a higher detection resolution.

[0024] In addition, in order to prevent the first sensing capacitor (Cd1+Cf1) from changing due to external influences, the capacitance detection circuit 20 must first complete the first adaptive capacitance mode before entering the first touch key mode. In other words, the capacitance detection circuit 20 needs to perform the first adaptive capacitance mode within a fixed period of time, and after entering the first touch key mode, different from Figure 1 The capacitance detection circuit 10 uses a general voltage detection method, that is, a comparator CP is used to detect whether the voltage Vcs reaches the reference voltage Vref. The capacitance detection circuit 20 also includes a voltage controlled oscillator (VCO) 201 for oscillating a first frequency and a second frequency ( Figure 2(not shown), wherein the first frequency is generated by the voltage Vcs2, and the second frequency is generated by the second power supply voltage Vb. Therefore, when the external power supply is interfered by noise, the voltage Vcs2 and the second power supply voltage Vb will also be interfered by noise at the same time, and the frequencies of the first frequency and the second frequency offsetting each other are still close to the same, so that the capacitance detection circuit 20 can eliminate the noise interference of the external power supply, or in other words, the use of the voltage-controlled oscillator 201 can synchronously offset the noise interference of the external power supply, so as to achieve a higher detection resolution.

[0025] It should be noted that after the switch SW1b is turned on to transfer the charge stored in the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2, the voltage Vcs2 of the storage capacitor Cs2 can be expressed as: Vcs2 = [Vcs2'*Cs+Va*(Cd1+Cf1)] / (Cs+Cd1+Cf1), where Vcs2' is the voltage Vcs2 before the switch SW1b is turned on to transfer the charge stored in the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2. In addition, after the switch SW2b is turned on to transfer the charge stored in the storage capacitor Cs2 to the variable capacitor Cr, the voltage Vcs2 of the storage capacitor Cs2 can be expressed as: Vcs2 = Vcs2"*Cs / (Cs+Cf1), where Vcs2" is the voltage Vcs2 before the switch SW2b is turned on to transfer the charge stored in the storage capacitor Cs2 to the variable capacitor Cr. It can be seen that if Cr=(Cd1+Cf1), the amount of charge transferred from the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2 and from the storage capacitor Cs2 to the variable capacitor Cr is equal each time, so when the first adaptive capacitance mode is completed, the voltage Vcs2 of the storage capacitor Cs2 will be equal to the second power supply voltage Vb, or the voltage Vcs2 of the storage capacitor Cs2 can be stably maintained near the second power supply voltage Vb, so that the voltage controlled oscillator 201 can stably oscillate the first frequency and the second frequency that are the same or close to the same. Since the details of adjusting the variable capacitor Cr have been described in the above content, they will not be repeated here.

[0026] On the other hand, Figure 2As shown, in the first touch key mode, the capacitance detection circuit 20 will first turn on the switch SW1a and the switch SW1b at the same time, provide a discharge path to discharge the voltage of the variable capacitor Cr to the ground voltage GND, and provide a first charge transfer path to transfer the charge stored in the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2, and then turn off the switch SW1a and the switch SW1b at the same time. Secondly, the capacitance detection circuit 20 will turn on the switch SW2a and the switch SW2b at the same time, so that the first charging path is provided to charge the voltage of the first sensing capacitor (Cd1+Cf1) to the first power supply voltage Va, and provide a second charge transfer path to transfer the charge stored in the storage capacitor Cs2 to the variable capacitor Cr, and then turn off the switch SW2a and the switch SW2b at the same time, and detect the capacitance value change of the first sensing capacitor (Cd1+Cf1) according to the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr. Please note that it is clear from the above content that the capacitance detection circuit 20 does not use the voltage detection value, but in fact, the first frequency and the second frequency oscillated by the voltage-controlled oscillator 201 still reflect the voltage Vcs2 and the second power supply voltage Vb. Therefore, at this time, the capacitance detection circuit 20 can still be regarded as comparing the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr with the second power supply voltage Vb, and detecting the capacitance change of the first sensing capacitor (Cd1+Cf1) according to the comparison result.

[0027] For example, if the voltage Vcs2 is equal to the second power supply voltage Vb at this time, it means that the capacitance value of the first sensing capacitor (Cd1+Cf1) has not changed. In contrast, if the voltage Vcs2 is greater than the second power supply voltage Vb at this time, it means that the capacitance value of the first sensing capacitor (Cd1+Cf1) has increased, so the capacitance detection circuit 20 can repeatedly provide the discharge path plus the first charge transfer path and the first charging path plus the second charge transfer path of the variable capacitor Cr, or cyclically turn on the switches SW1a+SW1b and the switches SW2a+SW2b until a fixed time later, if the voltage difference between the voltage Vcs2 and the second power supply voltage Vb becomes larger and larger, or the voltage difference tends to be stable, then the microcontroller 4 can determine that the finger has pressed the first conductor according to the change in the capacitance value of the first sensing capacitor (Cd1+Cf1), and if the voltage difference between the voltage Vcs2 and the second power supply voltage Vb becomes smaller and smaller, the microcontroller 4 can also determine that the finger is moving away from the first conductor.

[0028] In addition, if Figure 2As shown, the capacitance detection circuit 20 may further include a counter 203 and a touch value register 209. The counter 203 is coupled to the voltage-controlled oscillator 201, and is used to store at least one value generated by the voltage-controlled oscillator 201. Based on the at least one value, the counter 203 can generate a first touch value to reflect the change in the capacitance value of the first sensing capacitor (Cd1+Cf1). For example, when a finger presses the first conductor, even if the first parasitic capacitance Cd1 remains unchanged, the first finger capacitance Cf1 changes from 0pF to about 0.5pF, so that the charging increases, causing the voltage Vcs2 to rise, and the first frequency oscillated by the voltage-controlled oscillator 201 also rises relatively. Therefore, within a fixed time, the value stored in the counter 203 will increase and generate a corresponding first touch value, so that the microcontroller 4 can determine whether the finger presses the first conductor based on the first touch value. In contrast, when the finger leaves the conductor, the finger capacitance Cf returns to 0pF, so that the charge is reduced, causing the voltage Vcs2 to drop, and the first frequency oscillated by the voltage-controlled oscillator 201 also decreases relatively. Therefore, within a fixed time, the value stored in the counter 203 will become smaller and generate a corresponding first touch value, so that the microcontroller 4 can determine that the finger is not pressing the first conductor according to the first touch value. In short, the operating principles of the touch value generated by the counter 203 and the microcontroller 4 judging the finger pressing state by the touch value on the counter 203 are all known to technicians in this technical field, so the details are not repeated.

[0029] It should be understood that the touch value register 209 is used to store the first touch value. As mentioned above, the longer the time when the microcontroller 4 is in the state of judging the finger pressing the key is, the more power it consumes. Figure 2 As shown, the touch value comparator 22 is coupled to the capacitance detection circuit 20 and the microcontroller 4, and determines whether to generate an interrupt signal IS to the microcontroller 4 according to the first touch value, so as to instruct the microcontroller 4 to read the first touch value from the touch value register 209. In this embodiment, the touch value comparator 22 can be coupled to the touch value register 209, and is used to determine whether the first touch value exceeds or is lower than at least one threshold value. When the first touch value exceeds or is lower than at least one threshold value, the touch value comparator 22 decides to generate an interrupt signal IS to the microcontroller 4, so as to instruct the microcontroller 4 to read the first touch value. In other words, regardless of whether the microcontroller 4 is in a sleep state or a working state, the microcontroller 4 does not need to actively read the first touch value, but only when the touch value comparator 22 sends an interrupt signal IS, the microcontroller 4 needs to read the first touch value. It can be seen that when the microcontroller 4 is in the sleep state, the present embodiment can achieve the purpose of saving power, and when the microcontroller 4 is in the working state, the present embodiment can achieve the purpose of saving the performance of the microcontroller 4 because the microcontroller 4 does not need to read the first touch value all the time.

[0030] It is worth mentioning that, as mentioned above, the capacitance value of the parasitic capacitance Cd is not consistent on each touch key (i.e., conductor). Therefore, for a product with multiple touch keys, the capacitance detection circuit 20 can make each touch key have a capacitance value corresponding to a variable capacitance Cr. For example, assuming Figure 2 The capacitance detection circuit 20 is coupled to six conductors, namely the first to sixth conductors ( Figure 2 If the capacitance detection circuit 20 is coupled to the second conductor through the pin P2, and the capacitance value of the variable capacitor Cr is adjusted in the second adaptive capacitance mode, and by analogy, the capacitance detection circuit 20 can be coupled to the sixth conductor through the pin P6, and the capacitance value of the variable capacitor Cr is adjusted in the sixth adaptive capacitance mode, so that the touch value of each touch key on the counter 203 can be consistent. In other words, this embodiment can solve the problem of inconsistent touch values ​​caused by different parasitic capacitances Cd when multiple touch keys are laid out on the PCB. It should also be understood that in the second adaptive capacitance mode, the storage capacitor Cs2 is charged by the second sensing capacitor (Cd2+Cf2), and the variable capacitor Cr is discharged by it. By analogy, in the sixth adaptive capacitance mode, the storage capacitor Cs2 is charged by the sixth sensing capacitor (Cd6+Cf6), and the variable capacitor Cr is discharged by it. Since the operating principle of the capacitance detection circuit 20 in each adaptive capacitance mode is similar to the above description, it will not be described in detail here.

[0031] In contrast, when entering the second touch key mode, the capacitance detection circuit 20 detects the capacitance change of the second sensing capacitor (Cd2+Cf2) to generate a second touch value related to the second conductor. Similarly, when entering the sixth touch key mode, the capacitance detection circuit 20 detects the capacitance change of the sixth sensing capacitor (Cd6+Cf6) to generate a sixth touch value related to the sixth conductor. Since the operating principle of the capacitance detection circuit 20 in each touch key mode is similar to the above description, it will not be described in detail here. It can be seen that the capacitance detection circuit 20 may also include a touch guide 211, coupled to the touch value comparator 22 and the variable capacitance controller 207, so that when the touch value comparator 22 determines whether to generate the interrupt signal IS, the touch guide 211 will guide the capacitance detection circuit 20 to perform its corresponding touch key mode for the next conductor, and the touch guide 211 will also instruct the variable capacitance controller 207 to adjust the capacitance value of the variable capacitor Cr to the capacitance value of the variable capacitor Cr adjusted in the adaptive capacitance mode of the next conductor. In practice, the touch guide 211 can couple the capacitance detection circuit 20 to one of the conductors through a multiplexer to perform its corresponding adaptive capacitance mode or touch key mode, but the present invention is not limited thereto.

[0032] That is, the touch guide 211 will record the capacitance value of the variable capacitor Cr adjusted by the variable capacitor controller 207 in the adaptive capacitance mode of each conductor, and in the touch key mode of each conductor, the touch guide 211 will adjust the capacitance value of the variable capacitor Cr at this time through the variable capacitor controller 207, so that the touch value of each conductor on the counter 203 can be consistent. It should be noted that in this embodiment, the microcontroller 4 can be used to set the touch guide 211 to only guide the capacitance detection circuit 20 to certain conductors to perform their corresponding touch key modes, or the microcontroller 4 can be used to set the touch guide 211 to guide the capacitance detection circuit 20 to each conductor one by one (i.e., automatic circulation) to perform its corresponding touch key mode, but the present invention is not limited to this, and technicians in this technical field should be able to perform relevant designs according to actual needs or applications.

[0033] It is worth noting that in one design, the counter 203 can average the value generated by the voltage-controlled oscillator 201 each time with the values ​​generated in the previous times, such as the previous 15 times, and allow the microcontroller 4 to only read the average value from the touch value register 209. Therefore, whenever a new value is generated, the present embodiment immediately outputs an average value, and the present embodiment may refer to this design as a cumulative mode; or, in another design, the counter 203 can sequentially place the generated multiple touch values, i.e., the first to sixth touch values, into the touch value register 209, and allow the microcontroller 4 to read them one by one, and the present embodiment may refer to this design as a true value mode, but the present invention is not limited to this. As mentioned above, the operating principle of the touch value generated by the counter 203 and the microcontroller 4 judging the finger pressing state by the touch value on the counter 203 are already known to those skilled in the art, so the details will not be repeated.

[0034] Finally, in order to further explain the operation process of the capacitive touch device 2, the present invention further provides an implementation of its operation method. Figure 3 , Figure 3 is a flowchart of the steps of the operation method provided by the embodiment of the present invention. It should be noted that, Figure 3 The operation method can be used for Figure 2 Therefore, please refer to the capacitive touch device 2. Figure 2 For ease of understanding, but the present invention is not limited to Figure 3 The operation method can only be used for Figure 2 Similarly, for the convenience of the following description, Figure 3The operating method of the capacitance detection circuit 20 is only illustrated as being coupled to one conductor, namely, the first conductor. However, for the operating method of the capacitance detection circuit 20 being coupled to multiple conductors, such as the first to sixth conductors, technicians in this technical field should be able to modify and expand the contents provided in this specification, so it will not be elaborated here.

[0035] like Figure 3 As shown, in step S301, the capacitance detection circuit 20 adjusts the capacitance value of the variable capacitor Cr in the first adaptive capacitance mode so that the capacitance value of the variable capacitor Cr is equal to the capacitance value of the current first sensing capacitor (Cd1+Cf1). Secondly, in step S302, the capacitance detection circuit 20 detects the capacitance value change of the first sensing capacitor (Cd1+Cf1) in the first touch key mode to generate a first touch value related to the first conductor, and in step S303, the first touch value is stored in the touch value register 209. Then, in step S304, according to the first touch value, the touch value comparator 22 determines whether to generate an interrupt signal IS to the microcontroller 4. If so, step S305 is executed to send an interrupt signal IS to instruct the microcontroller 4 to read the first touch value from the touch value register 209; if not, return to step S302. In step S304, the touch value comparator 22 can determine whether to generate an interrupt signal IS to the microcontroller 4 by determining whether the first touch value exceeds or is lower than at least one threshold value. For example, when the first touch value exceeds or is lower than at least one threshold value, the touch value comparator 22 determines to generate an interrupt signal IS to the microcontroller 4.

[0036] Please also refer to Figure 4 , Figure 4 2 is a flowchart of the operation method of the capacitance detection circuit 20 in the first adaptive capacitance mode and the first touch key mode. Figure 4 It also only illustrates the operation method of the first adaptive capacitance mode and the first touch key mode of the capacitance detection circuit 20 coupled to one conductor, that is, the first conductor. However, for the operation method of the first to sixth adaptive capacitance modes and the first to sixth touch key modes of the capacitance detection circuit 20 coupled to multiple conductors, such as the first to sixth conductors, those skilled in the art should be able to modify and expand the contents provided in this specification, so it will not be repeated here. Figure 4As shown, in step S401 in the first adaptive capacitance mode, a first charging path is provided to charge the voltage Vdf of the first sensing capacitor (Cd1+Cf1) to the first power supply voltage Va, and a second charging path is provided to charge the voltage Vcs2 of the storage capacitor Cs2 to the second power supply voltage Vb. Secondly, in step S402 in the first adaptive capacitance mode, a discharging path is provided to discharge the voltage of the variable capacitor Cr to the ground voltage GND, and a first charge transfer path is provided to transfer the charge stored in the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2.

[0037] Next, in step S403 under the first adaptive capacitance mode, a first charging path is provided to charge the voltage Vdf of the first sensing capacitor (Cd1+Cf1) to the first power supply voltage Va, and a second charge transfer path is provided to transfer the charge stored in the storage capacitor Cs2 to the variable capacitor Cr. Then, in step S404 under the first adaptive capacitance mode, it is checked whether the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr is equal to the second power supply voltage Vb. If not, step S405 is executed to adjust the capacitance value of the variable capacitor Cr according to the comparison result between the voltage Vcs2 and the second power supply voltage Vb, and after completing step S405, return to execute steps S402 to S404. In other words, steps S402 to S405 will be repeatedly executed until the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr is equal to the second power supply voltage Vb, and the capacitance detection circuit 20 is considered to have completed the adaptive capacitance mode.

[0038] In addition, in step S406 in the first touch key mode, a discharge path is provided to discharge the voltage of the variable capacitor Cr to the ground voltage GND, and a first charge transfer path is provided to transfer the charge stored in the first sensing capacitor (Cd1+Cf1) to the storage capacitor Cs2. Then, in step S407 in the first touch key mode, a first charging path is provided to charge the voltage of the first sensing capacitor (Cd1+Cf1) to the first power supply voltage Va, and a second charge transfer path is provided to transfer the charge stored in the storage capacitor Cs2 to the variable capacitor Cr. Then, in step S408 in the first touch key mode, the capacitance value change of the first sensing capacitor (Cd1+Cf1) is detected according to the voltage Vcs2 of the storage capacitor Cs2 after the charge is transferred to the variable capacitor Cr, and after completing step S408, the execution of steps S406 to S408 is returned. In other words, step S406 to step S408 are repeatedly executed, so that the capacitance detection circuit 20 can generate a first touch value related to the first conductor to reflect the capacitance change of the first sensing capacitor (Cd1+Cf1).

[0039] In summary, the embodiment of the present invention provides a capacitive touch device and its operation method, which integrates the storage capacitor into a single chip to avoid the misjudgment of detection caused by the change of ambient temperature and humidity, and allows each touch button to have a capacitance value corresponding to a variable capacitor, or in other words, by adjusting the capacitance value of the variable capacitor in each adaptive capacitance mode, the touch value of each touch button on the counter can be consistent, thereby solving the problem of inconsistent touch values ​​caused by different parasitic capacitances when multiple touch buttons are laid out on the PCB. In addition, regardless of whether the microcontroller is in a dormant or working state, the microcontroller does not need to actively read the touch value on the counter, but only needs to read the touch value on the counter when the touch value comparator sends an interrupt signal. It can be seen that when the microcontroller is in a dormant state, the present invention can achieve the purpose of saving power, and when the microcontroller is in a working state, the present invention can achieve the purpose of saving the microcontroller performance because the microcontroller does not need to read the touch value all the time.

[0040] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the claims of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention's specification and drawings are included in the claims of the present invention.

Claims

1. A capacitive touch device, coupled between a first conductor and a microcontroller, characterized in that: The capacitive touch device comprises: a capacitance detection circuit coupled to the first conductor and the microcontroller, for detecting a capacitance change of a first sensing capacitor in a first touch key mode to generate a first touch value related to the first conductor; and a touch value comparator coupled to the capacitance detection circuit and the microcontroller, and determining whether to generate an interrupt signal to the microcontroller according to the first touch value to instruct the microcontroller to read the first touch value; The capacitance detection circuit includes a storage capacitor and a variable capacitor, and the capacitance detection circuit is further used to adjust the capacitance value of the variable capacitor in a first adaptive capacitance mode, wherein in the first adaptive capacitance mode, the capacitance detection circuit is used to perform: Step S1, providing a first charging path to charge the voltage of the first sensing capacitor to a first power supply voltage, and providing a second charging path to charge the voltage of the storage capacitor to a second power supply voltage, wherein the second power supply voltage is less than the first power supply voltage, and the first sensing capacitor includes a first parasitic capacitor and a first finger capacitor; Step S2, providing a discharge path to discharge the voltage of the variable capacitor to a ground voltage, and providing a first charge transfer path to transfer the charge stored in the first sensing capacitor to the storage capacitor; Step S3, providing the first charging path to charge the voltage of the first sensing capacitor to the first power supply voltage, and providing a second charge transfer path to transfer the charge stored in the storage capacitor to the variable capacitor, and then comparing the voltage of the storage capacitor after the charge is transferred to the variable capacitor with the second power supply voltage, and adjusting the capacitance value of the variable capacitor according to the comparison result; and Step S4, repeating step S2 and step S3 until the voltage of the storage capacitor after the charge is transferred to the variable capacitor is equal to the second power supply voltage, and the capacitance detection circuit completes the first adaptive capacitance mode.

2. The capacitive touch device according to claim 1, wherein: In the first touch key mode, the capacitance detection circuit is used to perform: Step S5, providing the discharge path to discharge the voltage of the variable capacitor to the ground voltage, and providing the first charge transfer path to transfer the charge stored in the first sensing capacitor to the storage capacitor; Step S6, providing the first charging path to charge the voltage of the first sensing capacitor to the first power supply voltage, and providing the second charge transfer path to transfer the charge stored in the storage capacitor to the variable capacitor, and then detecting the capacitance change of the first sensing capacitor according to the voltage of the storage capacitor after the charge is transferred to the variable capacitor; as well as Step S7, repeating step S5 and step S6, so that the capacitance detection circuit can generate the first touch value to reflect the capacitance value change of the first sensing capacitor.

3. The capacitive touch device according to claim 2, wherein: The storage capacitor and the capacitance detection circuit are integrated into a single chip, and the capacitance detection circuit further includes: an internal voltage regulator for generating the first power supply voltage and the second power supply voltage; a variable capacitor controller, used to adjust the capacitance value of the variable capacitor according to the comparison result of step S3; a voltage-controlled oscillator for simultaneously oscillating a first frequency and a second frequency, wherein the first frequency is generated by controlling the voltage of the storage capacitor, and the second frequency is generated by controlling the second power supply voltage; a counter, coupled to the voltage-controlled oscillator, for storing at least one value generated by the voltage-controlled oscillator, and generating the first touch value according to the at least one value to reflect the capacitance change of the first sensing capacitor; and A touch value register is used to store the first touch value.

4. The capacitive touch device according to claim 3, wherein: The capacitance detection circuit is further coupled to a second conductor and is used to adjust the capacitance value of the variable capacitor in a second adaptive capacitance mode and detect the capacitance value change of a second sensing capacitor in a second touch key mode to generate a second touch value related to the second conductor.

5. The capacitive touch device according to claim 4, wherein: The capacitance detection circuit also includes: A touch guide is coupled to the touch value comparator and the variable capacitor controller, and is used to guide the capacitance detection circuit to perform the second touch key mode for the second conductor after the touch value comparator determines whether to generate the interrupt signal, and the touch guide will also instruct the variable capacitor controller to adjust the capacitance value of the variable capacitor to the capacitance value of the variable capacitor adjusted in the second adaptive capacitance mode of the second conductor.

6. The capacitive touch device according to claim 1, wherein: In the comparison result of step S3, if the voltage of the storage capacitor is greater than the second power supply voltage, the capacitance detection circuit increases the capacitance value of the variable capacitor, and if the voltage of the storage capacitor is less than the second power supply voltage, the capacitance detection circuit decreases the capacitance value of the variable capacitor.

7. An operating method for a capacitive touch device, characterized in that: The capacitive touch device includes a capacitance detection circuit and a touch value comparator. The capacitance detection circuit is coupled to a first conductor and a microcontroller. The operating method includes: The capacitance detection circuit detects a capacitance change of a first sensing capacitor in a first touch key mode to generate a first touch value related to the first conductor; and According to the first touch value, the touch value comparator determines whether to generate an interrupt signal to the microcontroller to instruct the microcontroller to read the first touch value; The capacitance detection circuit includes a storage capacitor and a variable capacitor, and the capacitance detection circuit is further used to adjust the capacitance value of the variable capacitor in a first adaptive capacitance mode, wherein in the first adaptive capacitance mode, the capacitance detection circuit is used to perform: Step S1, providing a first charging path to charge the voltage of the first sensing capacitor to a first power supply voltage, and providing a second charging path to charge the voltage of the storage capacitor to a second power supply voltage, wherein the second power supply voltage is less than the first power supply voltage, and the first sensing capacitor includes a first parasitic capacitor and a first finger capacitor; Step S2, providing a discharge path to discharge the voltage of the variable capacitor to a ground voltage, and providing a first charge transfer path to transfer the charge stored in the first sensing capacitor to the storage capacitor; Step S3, providing the first charging path to charge the voltage of the first sensing capacitor to the first power supply voltage, and providing a second charge transfer path to transfer the charge stored in the storage capacitor to the variable capacitor, and then comparing the voltage of the storage capacitor after the charge is transferred to the variable capacitor with the second power supply voltage, and adjusting the capacitance value of the variable capacitor according to the comparison result; and Step S4, repeating step S2 and step S3 until the voltage of the storage capacitor after the charge is transferred to the variable capacitor is equal to the second power supply voltage, and the capacitance detection circuit completes the first adaptive capacitance mode.

8. The operating method according to claim 7, characterized in that: In the first touch key mode, the capacitance detection circuit is used to perform: Step S5, providing the discharge path to discharge the voltage of the variable capacitor to the ground voltage, and providing the first charge transfer path to transfer the charge stored in the first sensing capacitor to the storage capacitor; Step S6, providing the first charging path to charge the voltage of the first sensing capacitor to the first power supply voltage, and providing the second charge transfer path to transfer the charge stored in the storage capacitor to the variable capacitor, and then detecting the capacitance change of the first sensing capacitor according to the voltage of the storage capacitor after the charge is transferred to the variable capacitor; as well as Step S7, repeating step S5 and step S6, so that the capacitance detection circuit can generate the first touch value to reflect the capacitance value change of the first sensing capacitor.

9. The operating method according to claim 8, characterized in that: The storage capacitor and the capacitance detection circuit are integrated into a single chip, and the capacitance detection circuit further includes: an internal voltage regulator for generating the first power supply voltage and the second power supply voltage; a variable capacitor controller, used to adjust the capacitance value of the variable capacitor according to the comparison result of step S3; a voltage-controlled oscillator for simultaneously oscillating a first frequency and a second frequency, wherein the first frequency is generated by controlling the voltage of the storage capacitor, and the second frequency is generated by controlling the second power supply voltage; a counter, coupled to the voltage-controlled oscillator, for storing at least one value generated by the voltage-controlled oscillator, and generating the first touch value according to the at least one value to reflect the capacitance change of the first sensing capacitor; and A touch value register is used to store the first touch value.

10. The operating method according to claim 9, characterized in that: The capacitance detection circuit is further coupled to a second conductor and is used to adjust the capacitance value of the variable capacitor in a second adaptive capacitance mode and detect the capacitance value change of a second sensing capacitor in a second touch key mode to generate a second touch value related to the second conductor.

11. The operating method according to claim 10, characterized in that: The capacitance detection circuit also includes: A touch guide is coupled to the touch value comparator and the variable capacitor controller, and is used to guide the capacitance detection circuit to perform the second touch key mode for the second conductor after the touch value comparator determines whether to generate the interrupt signal, and the touch guide will also instruct the variable capacitor controller to adjust the capacitance value of the variable capacitor to the capacitance value of the variable capacitor adjusted in the second adaptive capacitance mode of the second conductor.

12. The operating method according to claim 7, characterized in that: In the comparison result of step S3, if the voltage of the storage capacitor is greater than the second power supply voltage, the capacitance detection circuit increases the capacitance value of the variable capacitor, and if the voltage of the storage capacitor is less than the second power supply voltage, the capacitance detection circuit decreases the capacitance value of the variable capacitor.

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