Capacitance detection unit, touch device and interactive equipment

Abstract

The embodiment of the invention provides a capacitance detection unit, a touch device and interactive equipment. The capacitance detection unit controls starting and ending of a sampling process through a sampling module, guarantees accuracy of sampling control starting time and ending time, and can adjust sampling time according to sampling requirements so as to improve sampling precision or reduce sampling energy consumption. Charges of a modulation capacitor are transferred to an induction capacitor in a charging and discharging mode, then the modulation capacitor is charged to supplement charges lost due to charging, and capacitance change sampling of the induction capacitor is transferred to charging time sampling of the modulation capacitor. Therefore, not only can electrical isolation between the induction capacitor and the sampling module be realized and interference be reduced, but also the stability of the high-level signal and the low-level signal obtained by sampling can be improved, so that sampling errors caused by other factors in the circuit can be reduced through the high-level signal and the low-level signal, and the sampling accuracy is improved. And the capacitance detection precision can be improved.

Description

Technical Field

[0001] The present invention relates to the field of capacitance sensing technology, and in particular to a capacitance detection unit, a touch control device and an interactive device. Background Art

[0002] Capacitive sensing technology is currently widely used in various electronic products, such as IoT devices, consumer products, industrial products, and commercial products. In these product applications, capacitive sensing technology is mainly used to achieve capacitive touch, which can replace mechanical switches and knobs, so that users can interact with products through touch interaction interfaces or smart switches, or through proximity sensing switches, so that products can perform corresponding tasks based on instructions input by users through capacitive touch. In order to improve the user experience, the above-mentioned touch operation related detection may also need to support functions such as waterproof touch detection, wrist touch detection, and glove touch detection.

[0003] In order to realize the above-mentioned touch detection, in the field of capacitive sensing technology, a commonly used method is the self-capacitance detection method, which performs touch recognition by measuring the capacitance change between a single pin and the ground. When in use, the single pin is led out to form a sensing electrode, which is used to detect the capacitance change between the electrode and the ground caused by the approach of the user's finger or other parts. For example, according to the principle of parallel plate capacitance, it is known that the capacitance will increase when the finger approaches, so the interaction behavior can be distinguished based on the change in capacitance.

[0004] However, since the above self-capacitance detection method can only measure the capacitance change on one side, the resolution of the touch position is relatively low, resulting in low detection sensitivity. In order to maintain higher sensitivity, higher sampling frequencies and more complex signal processing algorithms are required, but this will also generate higher power consumption and electromagnetic interference (EMI). Summary of the invention

[0005] In view of this, an object of the present invention is to provide a capacitance detection unit, a touch control device and an interactive equipment, so as to at least improve the detection sensitivity and accuracy of capacitance changes.

[0006] In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:

[0007] According to a first aspect of an embodiment of the present invention, a capacitance detection unit is provided, including:

[0008] Sensing capacitor, used to detect the capacitance change at the sensing electrode;

[0009] A charging and discharging module, used to control the alternating charging and discharging of the sensing capacitor according to a source clock signal during the sampling process;

[0010] A current modulation module, comprising a modulation capacitor; the current modulation module is used to: during the charging process of the induction capacitor, control the modulation capacitor to charge the induction capacitor; when the voltage of the modulation capacitor is lower than a reference voltage, output a high level signal, and charge the modulation capacitor until the voltage of the modulation capacitor is higher than the reference voltage; and when the voltage of the modulation capacitor is higher than the reference voltage, output a low level signal;

[0011] and a sampling module, which is used to control the start and end of the sampling process, and in the sampling process, when the current modulation module outputs a high-level signal, cumulatively count the number of cycles of the source clock signal until the current modulation module outputs the low-level signal, so as to obtain a total value in the sampling process; the total value is used to characterize the capacitance change of the inductive capacitor.

[0012] In the embodiment of the present invention, on the one hand, by using the sampling module itself to control the start and end of the sampling process, the accuracy of the start time and end time of the sampling control can be guaranteed, and it can be adjusted according to the sampling requirements, for example, according to the accuracy requirements or low power consumption requirements to extend or shorten the sampling time to improve the sampling accuracy or reduce the sampling energy consumption, wherein the extension of the sampling time can make it go through multiple sampling cycles in one sampling process, because in each sampling process, it is cumulative counting, so the longer the sampling time, the higher the sensitivity, reliability and accuracy of the sampling. On the other hand, by transferring the charge of the modulation capacitor to the sensing capacitor in a charging and discharging manner, and then charging the modulation capacitor to supplement the charge lost due to charging, and transferring the capacitance change sampling of the sensing capacitor to the charging time sampling of the modulation capacitor (i.e., the duration of the high-level signal), not only can the electrical isolation between the sensing capacitor and the sampling module be achieved, interference can be reduced, but also the stability of the high-level signal and the low-level signal obtained by sampling can be improved, and then the sampling error caused by other factors in the circuit can be reduced by the high-level signal and the low-level signal, which is conducive to improving the capacitance detection accuracy. On the other hand, the sampling module accumulates and counts the number of cycles of the source clock signal that the charging and discharging module realizes to alternately control the charging and discharging of the inductive capacitor, which can ensure the time consistency of the high-level signal and the low-level signal with the source clock signal, which is conducive to further improving the capacitance detection accuracy calculated by the total value obtained by counting. It can be seen that there is no need to use complex signal processing algorithms to achieve improved sensitivity.

[0013] In an optional embodiment, the charging and discharging module includes:

[0014] A first switch, one end of which is grounded and the other end of which is connected to the inductive capacitor, and is used to discharge the inductive capacitor when it is turned on;

[0015] A second switch, one end of which is connected to the induction capacitor and the other end of which is connected to the modulation capacitor, and is used to charge the induction capacitor through the modulation capacitor when it is turned on;

[0016] A frequency divider, used for performing frequency division processing on the source clock signal to output a frequency-divided clock signal;

[0017] and a spread spectrum clock generator connected to the output end of the frequency divider, for controlling the first switch and the second switch to be alternately disconnected and turned on according to the divided clock signal.

[0018] By using a spread spectrum clock generator to provide a beating clock frequency to control the first switch and the second switch to be alternately disconnected and turned on, thereby realizing the alternate charging and discharging of the inductive capacitor, the electromagnetic interference (EMI) caused by the fixed clock frequency can be reduced, thereby effectively reducing the peak value of electromagnetic radiation. In addition, the charging and discharging module of the above-mentioned structure has the advantages of simple structure and low manufacturing cost.

[0019] In an optional implementation, the current modulation module further includes:

[0020] a modulation current source connected to one end of the modulation capacitor connected to the second switch, and used for charging the modulation capacitor when the low level signal is output;

[0021] A switch circuit, comprising a third switch connected in series between the modulation capacitor and the modulation current source;

[0022] A comparator, wherein a positive input terminal is connected to the reference voltage, an inverting input terminal is connected to one end of the modulation capacitor connected to the second switch, and is used to output the high level signal when the voltage of the modulation capacitor is lower than the reference voltage, and output the low level signal when the voltage of the modulation capacitor is higher than the reference voltage;

[0023] and a latch, whose signal input end is connected to the output end of the comparator, whose signal output end is respectively connected to the switch circuit and the sampling module, and whose clock input end is used to connect to the source clock signal; the latch is used to control the third switch to be turned on and the sampling module to start counting when the comparator outputs the high level signal, and to control the third switch to be turned off and the sampling module to suspend counting when the comparator outputs the low level signal;

[0024] The other end of the modulation capacitor is grounded.

[0025] The current modulation module adopting the above structure has the advantages of simple structure and low manufacturing cost. In addition, a latch is configured at the output end of the comparator, and the output of the latch is used to control the on-off of the third switch and the counting of the acquisition module. Compared with directly using the output of the comparator as control, the stability of the output signal can be improved, and the signal turbulence can be avoided to affect the stability and accuracy of the on-off control of the third switch and the counting control of the acquisition module, which is conducive to further improving the capacitance detection accuracy.

[0026] In an optional implementation, the current modulation module further includes:

[0027] A compensation current source is connected to one end of the modulation capacitor connected to the second switch, and is used to charge and compensate the modulation capacitor.

[0028] By adding a compensation current source in the current modulation module, the compensation current source can be used to charge and compensate the modulation capacitor regardless of the sampling process or the non-sampling process. This can prevent the modulation capacitor from discharging too quickly and too much when the inductive capacitance is large, resulting in a large amount of charge transfer, which will cause the time required for the modulation capacitor to charge to the above-mentioned reference voltage to be prolonged, and may even exceed the sampling time, making it impossible to complete the complete sampling within the sampling time limited by the sampling process.

[0029] In an optional implementation, the switch circuit further includes a fourth switch; and the current modulation module further includes:

[0030] a charging buffer, wherein an input end of the charging buffer is connected to the reference voltage, and an output end of the charging buffer is connected to the modulation current source through the fourth switch;

[0031] The latch is further used to control the fourth switch to be turned off when the comparator outputs the high level signal, and to control the fourth switch to be turned on when the comparator outputs the low level signal.

[0032] By adding a fourth switch and a charging buffer, the terminal voltage of the modulation current can be maintained at the reference voltage at the moment of switching the third switch, which can effectively prevent the modulation current source from charging the modulation capacitor with too much charge at the moment of switching the third switch, thereby affecting the capacitance detection accuracy.

[0033] In an optional embodiment, the sampling module includes:

[0034] A counter, whose clock input terminal is used to access the source clock signal, whose enable terminal is connected to the signal output terminal of the latch, and whose count output terminal is used to output the total value;

[0035] And a timer, whose clock input end is used to access the source clock signal, the enable end is used to access the sampling trigger signal, and the control output end is used to access the control input end of the counter; the timer is used to clear the count value of the counter when receiving the sampling trigger signal, and control the counter to start counting, and control the counter to stop counting after setting the sampling time, so that the counter outputs the total value.

[0036] The sampling module using the above structure has the advantages of simple structure and low manufacturing cost. In addition, since the clock signal used by the counter and timer is consistent with the clock signal sampled by the charge and discharge module, the timing consistency between the three can be guaranteed, thereby improving the accuracy of the total value and further improving the capacitance detection accuracy.

[0037] In an optional embodiment, the sampling module further includes:

[0038] A pre-charge buffer, whose input terminal is connected to the reference voltage, and whose output terminal is connected to the inverting input terminal of the comparator through a fifth switch; the pre-charge buffer is used to stabilize the voltage of the modulation capacitor at the reference voltage when sampling starts.

[0039] By adding a pre-charging buffer in the sampling module, the voltage of the modulation capacitor is stabilized at the reference voltage at the beginning of sampling by using the pre-charging buffer, so as to control the charging timing of the modulation capacitor based on the reference voltage as mentioned above, so as to avoid the output result of the comparator being affected by the voltage of the modulation capacitor being too low or too high at the beginning of sampling, so that the charging time of the modulation capacitor tends to or is equal to the discharge time of the modulation capacitor to the sensing capacitor, thereby improving the counting accuracy.

[0040] In an optional embodiment, the inductive capacitor is formed by a copper foil inductive disk arranged on a circuit board, and the copper foil inductive disk is surrounded by a copper clad connected to a shielded motor; the capacitance detection unit also includes a shielding buffer, which is connected in series between the copper foil inductive disk and the copper clad, and is used to maintain the voltage of the copper foil inductive disk consistent with the voltage of the copper clad.

[0041] By adding a shielding buffer, the voltage of the copper foil sensing disk and the copper covering is kept consistent, that is, there is no potential difference between the copper foil sensing disk and the copper covering, so that the charge in the equivalent parasitic capacitance in the entire circuit system - the capacitance between the copper foil sensing disk and the copper covering (shielding electrode) can be prevented from flowing out or flowing into other conductors with a path, thereby affecting the sampling accuracy. Because there is no potential difference between the copper foil sensing disk and the copper covering, even if there are water droplets on the copper covering, the capacitance caused by the water droplets will be eliminated, and a waterproof effect can be achieved.

[0042] In an optional implementation, the capacitance detection unit further includes a low power consumption trigger module; the low power consumption trigger module includes:

[0043] Low speed clock source;

[0044] And a timing trigger, whose clock input end is connected to the low-speed clock source, and whose trigger output end is connected to the timer, is used to output the sampling trigger signal to the timer.

[0045] By adding a low-power trigger module, the power consumption of the circuit part involved in sampling can be reduced. Among them, using a low-speed clock source to provide a clock signal for a timing trigger can reduce the energy consumption of the clock source. In addition, using a timing trigger to trigger the start of the timer can avoid the timer being started all the time and generating more energy consumption.

[0046] In an optional implementation, the low power consumption trigger module further includes a counting comparator connected to a counting output terminal of the counter, the counting comparator being used to determine whether to send a wake-up signal according to the total value output by the counter and a set value range;

[0047] The capacitance detection unit also includes a control module, a signal input end of the control module is connected to an end of the counting comparator for outputting the wake-up signal, and the control end is connected to the timing trigger; the control module is used to increase the trigger frequency of the timing trigger when the wake-up signal is received, and reduce the trigger frequency of the timing trigger when the wake-up signal is not received within a set time.

[0048] By adding a counting comparator and a control module, the counting comparator is used to compare the total value with the set value range, and then determine whether to output a wake-up signal to wake up the control module based on the comparison result. In this way, the control module can be in sleep mode when it does not need to be woken up, thereby reducing the overall circuit power consumption. When the control module needs to be woken up, the trigger efficiency of the timing trigger can be increased, so that the sampling module can sample at a higher frequency, which can improve the sampling sensitivity.

[0049] In an optional implementation, the capacitance detection unit further includes:

[0050] A low-voltage dropout linear regulator, whose enable end is connected to the trigger output end of the timing trigger and whose input end is connected to a DC power supply; the low-voltage dropout linear regulator is used to provide working power for the charging and discharging module, the current modulation module and the sampling module;

[0051] The timing trigger is also used to control the low voltage difference linear regulator to supply power when the sampling trigger signal is output, and to control the low voltage difference linear regulator to stop supplying power when sampling is finished.

[0052] By adding a low-dropout linear regulator to provide working power for the charging and discharging module, current modulation module, sampling module and other circuit devices related to capacitor sampling, these circuit devices can have better anti-interference effect during the sampling process. On this basis, the working state of the low-dropout linear regulator is further controlled by a timing trigger, and the power supply of the above circuit devices can be turned off when sampling is not required, which is conducive to further reducing circuit power consumption.

[0053] In an optional embodiment, the inductive capacitor is provided in plurality; and the capacitance detection unit further includes:

[0054] A multi-way sorting / merging switch is connected in series between the plurality of sensing capacitors and the first switch, wherein the plurality of switch channels of the multi-way sorting / merging switch are respectively connected one by one with the plurality of sensing capacitors;

[0055] The control module is also used to control multiple switch channels in the multi-way sorting / merging switch to be turned on one by one when the wake-up signal is received, and to control multiple switch channels in the multi-way sorting / merging switch to be turned on in combination when the wake-up signal is not received within the set time period.

[0056] By adding a multi-way sorting / merging switch for a scenario in which the inductive capacitor is provided with multiple ones on the basis of an implementation method having a counting comparator, the control module can determine the scanning detection method of the inductive capacitor through the multi-way sorting / merging switch according to the change of the inductive capacitor. For example, when the control module receives a wake-up signal, it indicates that the inductive capacitor has changed. In order to find out which inductive capacitors have changed in capacitance value, multiple switch channels in the multi-way sorting / merging switch are controlled to be turned on one by one to perform polling scan on the inductive capacitor; and when the control module has not received a wake-up signal within a set time, it indicates that the inductive capacitor has not changed. At this time, in order to save circuit energy consumption, the control module controls multiple switch channels in the multi-way sorting / merging switch to be combined and turned on, and the outputs of all the inductive capacitors are combined into one to sample and determine whether the capacitance has changed, and then switch to polling scan when the change occurs.

[0057] In an optional embodiment, the inductive capacitor is provided in plurality; and the capacitance detection unit further includes:

[0058] A multi-way sorting / merging switch is connected in series between the plurality of sensing capacitors and the first switch, wherein the plurality of switch channels of the multi-way sorting / merging switch are respectively connected one by one with the plurality of sensing capacitors;

[0059] and a control module, which is used to control the multiple switch channels in the multi-way sorting / merging switch to be turned on one by one when the total value is not within the set value range, and to control the multiple switch channels in the multi-way sorting / merging switch to be turned on in combination when the total value is within the value range.

[0060] On the basis of an implementation method without a counting comparator, for scenarios in which multiple sensing capacitors are provided, the function of the counting comparator can be transferred to the control module, that is, the control module can control the working mode of the multi-way sorting / merging switch according to the total value and the value range, and then when all the sensing capacitors have not changed, multiple switch channels in the multi-way sorting / merging switch can be controlled to be combined and turned on to reduce sampling energy consumption.

[0061] According to a second aspect of the embodiments of the present invention, a touch control device is provided, comprising a capacitance detection unit provided by any one of the above-mentioned first aspects.

[0062] A third aspect of an embodiment of the present invention provides an interactive device, comprising a capacitance detection unit provided in any one of the first aspects above.

[0063] Since the touch control device and interactive equipment provided by the present invention include the capacitance detection unit provided by any one of the first aspects of the embodiments of the present invention, the touch control device and interactive equipment provided by the present invention also have the beneficial technical effects produced by the capacitance detection unit provided by any one of the first aspects above, which will not be elaborated here.

[0064] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0066] Figure 1 A structural block diagram of a capacitance detection unit provided by an embodiment of the present invention is shown;

[0067] Figure 2 A schematic diagram of a circuit structure of a capacitance detection unit provided in an embodiment of the present invention is shown;

[0068] Figure 3 A schematic diagram of the circuit structure of another capacitance detection unit provided in an embodiment of the present invention is shown.

[0069] Icon: 100-capacitance detection unit, 110-charging and discharging module, 120-current modulation module, 130-sampling module, 140-low power trigger module, Cs-sensing capacitor, Cc-modulation capacitor, Cp-equivalent parasitic capacitance, BUFF1-shielding buffer, BUFF2-charging buffer, BUFF3-pre-charging buffer, LDO-low voltage dropout linear regulator, S1-multi-way sorting / merging switch, SW1-first switch, SW2-second switch, SW3-third switch, SW4-fourth switch, SW5-fifth switch, CSS-spread spectrum clock generator, Ic-compensation current source, Im-modulation current source, CMP-comparator, VREF-reference voltage, LSI-low speed clock source, E-capacitance detection part in the capacitance detection unit. DETAILED DESCRIPTION

[0070] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0071] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0072] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0073] In the description of the present invention, it should be noted that if terms such as orientation are mentioned, for example, "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the corresponding drawings, or the orientation or position relationship in which the product of the invention is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0074] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" may simply mean that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0075] In the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", "connection", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, or an electrical connection; it can be directly connected, or connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] In order to solve the technical problems that the self-capacitance detection method in the related art can only measure the capacitance change on one side, so the resolution of the touch position is relatively low, which leads to low detection sensitivity, and the improvement of sensitivity requires reliance on complex signal processing algorithms, etc., the embodiment of the present invention first provides a capacitance detection unit. On the one hand, by using the sampling module itself to control the start and end of the sampling process, the accuracy of the sampling control start time and end time can be guaranteed, and it can be adjusted according to the sampling requirements. For example, the sampling time can be extended or shortened according to the accuracy requirements or low power consumption requirements to improve the sampling accuracy or reduce the sampling energy consumption. The extension of the sampling time can make multiple sampling cycles go through in one sampling process. Since the counting is accumulated in each sampling process, the longer the sampling time, the higher the sensitivity, reliability and accuracy of the sampling. On the other hand, by transferring the charge of the modulation capacitor to the sensing capacitor in a charging and discharging manner, and then charging the modulation capacitor to supplement the charge lost due to charging, and transferring the capacitance change sampling of the sensing capacitor to the charging time sampling of the modulation capacitor (i.e., the duration of the high-level signal), not only can the electrical isolation between the sensing capacitor and the sampling module be achieved, and interference can be reduced, but also the stability of the high-level signal and the low-level signal obtained by sampling can be improved, and then the sampling error caused by other factors in the circuit can be reduced by the high-level signal and the low-level signal, which is conducive to improving the capacitance detection accuracy. On the other hand, the number of cycles of the source clock signal that alternately controls the charging and discharging of the sensing capacitor is cumulatively counted by the sampling module, which can ensure the time consistency of the high-level signal and the low-level signal with the source clock signal, which is conducive to further improving the capacitance detection accuracy obtained by calculating the total value obtained by counting. It can be seen that there is no need to adopt a complex signal processing algorithm to achieve the improvement of sensitivity.

[0077] The following, combined Figure 2For a description of the capacitance detection unit provided in the embodiment of the present invention, please refer to Figure 2 , Figure 2 1 is a structural block diagram of a capacitance detection unit provided by an embodiment of the present invention; the capacitance detection unit 100 includes:

[0078] The sensing capacitor Cs is used to detect the capacitance change at the sensing electrode. In this embodiment, the sensing capacitor Cs may be an equivalent capacitor at the sensing electrode. When the capacitance value of the sensing capacitor Cs increases, it indicates that a touch object approaches or touches the corresponding part, for example, a user's finger or a stylus approaches or touches.

[0079] The charging and discharging module 110 is used to control the alternating charging and discharging of the sensing capacitor Cs according to the source clock signal during the sampling process. The source clock signal can be a high-speed internal (HSI) source signal, which can be provided by a separate clock generator or a clock source in an external control module.

[0080] The current modulation module 120 includes a modulation capacitor. The current modulation module 120 is used to: during the charging process of the inductive capacitor Cs, control the modulation capacitor to charge the inductive capacitor Cs; when the voltage of the modulation capacitor is lower than the reference voltage, output a high-level signal, and charge the modulation capacitor until the voltage of the modulation capacitor is higher than the reference voltage; and when the voltage of the modulation capacitor is higher than the reference voltage, output a low-level signal. The value of the reference voltage can be set according to actual application requirements. For example, it can be determined based on at least one of the variation range of the inductive capacitor Cs in the actual application product of the capacitance detection unit, the capacitance of the modulation capacitor, and the sampling time. The determination principle can be learned in combination with the relevant technology and the relevant description in the present invention, which will not be elaborated here.

[0081] and a sampling module 130, which is used to control the start and end of the sampling process, and during the sampling process, when the current modulation module 120 outputs a high-level signal, cumulatively count the number of cycles of the source clock signal until the current modulation module 120 outputs the low-level signal, so as to obtain a total value in the sampling process; the total value is used to characterize the capacitance change of the inductive capacitor Cs.

[0082] In the above, the charging and discharging module 110 can be implemented by a circuit in any related technology that can control the alternating charging and discharging of the sensing capacitor Cs according to the source clock signal. The principle of implementing the charging and discharging control of the sensing capacitor Cs according to the source clock signal can be found in the related technology and will not be described in detail here.

[0083] Similarly, based on the above description of the current modulation module 120 and the sampling module 130 , various implementation methods of the current modulation module 120 and the sampling module 130 can also be obtained from related technologies.

[0084] It is worth noting that the above description does not mean that the charging and discharging module 110, the current modulation module 120 and the sampling module 130 are all structures disclosed in the relevant technology, but means that under the premise of the inventive concept of the charging and discharging module 110, the current modulation module 120 and the sampling module 130 proposed in the embodiment of the present invention, those skilled in the art can obtain from the relevant technology a variety of circuit schemes that can realize the functions of the charging and discharging module 110, the current modulation module 120 and the sampling module 130 recorded in the embodiment of the present invention. Therefore, it should not be considered that the charging and discharging module 110, the current modulation module 120 and the sampling module 130 provided in the embodiment of the present invention are only the implementation methods described below. The implementation methods described below are some improved schemes proposed to achieve better technical effects.

[0085] The capacitance detection unit 100 provided in the embodiment of the present invention can be used as an independent circuit module product and assembled in a touch device or interactive equipment; or it can be used as a part of a touch device or interactive equipment and assembled in the touch device or interactive equipment before leaving the factory and sold together with the touch device or interactive equipment. The interactive equipment includes but is not limited to: smart phones, tablet computers, laptop computers, televisions, display devices and home appliances with capacitive touch function.

[0086] When the capacitance detection unit provided by the embodiment of the present invention is applied to a touch device or an interactive device, the relevant working principle of the capacitance detection unit 100 to implement touch detection is as follows:

[0087] After the capacitance detection unit is powered on, the sampling module 130 can periodically control the start and end of sampling according to the internally set timing program. At the beginning of each sampling, the sampling module 130 will clear its internal count to ensure the accuracy of each sampling result in the subsequent sampling process. Then the sampling process can be formally entered. During the sampling process, the charging and discharging module 110 alternately controls the charging and discharging of the sensing capacitor Cs under the source clock signal. When the sensing capacitor Cs is in the discharge mode, the sensing capacitor Cs will be equivalent to a grounded resistor and will continue to discharge to the ground. When the sensing capacitor Cs is in the charging mode, the modulation capacitor in the current modulation module 120 charges the sensing capacitor Cs, so the voltage of the modulation capacitor gradually decreases. When the voltage of the modulation capacitor is lower than the reference voltage, the current modulation module 120 will output a high-level signal to the sampling module 130 to control the sampling module 130 to count the number of cycles of the source clock signal. At the same time, the current modulation module 120 will also start the function of charging the modulation capacitor so that the voltage of the modulation capacitor gradually increases. When the voltage of the modulation capacitor is higher than the reference voltage, the current modulation module 120 will output a low-level signal to the sampling module 130. At this time, the sampling module 130 will pause counting. It can be seen that this is a complete sampling cycle.

[0088] If the sampling time between the start and end of the sampling process controlled by the sampling module 130 is greater than one sampling cycle, for example, when a sampling process includes three sampling cycles, the sampling module 130 will count three times. It is worth noting that in a sampling process, the count value is cumulative, that is, assuming that the count value of the first sampling cycle is A1, the count value corresponding to the second sampling cycle is A1+A2, where A2 is the count value added in the second sampling cycle. Similarly, the count value corresponding to the third sampling cycle is A1+A2+A3, where A3 is the count value added in the third sampling cycle. Based on this example, after the end of this round of sampling process, the total value obtained is A1+A2+A3. Then, the capacitance detection unit can send the obtained total value to the control module in the touch device or interactive device, and the control module calculates the corresponding capacitance value according to the total value and the frequency of the source clock signal, and judges whether there is a finger or stylus touch on the touch module for receiving touch information based on the size of the capacitance value, and in the case of judging that there is a touch, further judges the touch position according to the size of the capacitance value. Thus, capacitance detection and touch detection are realized.

[0089] Although the above technical solution can achieve a very good capacitance detection effect, in order to further reduce the electromagnetic interference caused by the fixed clock frequency, in some embodiments, refer to Figure 2 , Figure 2is a schematic diagram of a circuit structure of a capacitance detection unit provided in an embodiment of the present invention. An embodiment of the present invention provides an implementation scheme of a charging and discharging module 110, that is, the charging and discharging module 110 includes:

[0090] A first switch SW1, one end of which is grounded and the other end of which is connected to the sensing capacitor Cs, and is used to discharge the sensing capacitor Cs when it is turned on;

[0091] A second switch SW2, one end of which is connected to the sensing capacitor Cs, and the other end of which is connected to the modulation capacitor Cc, and is used to charge the sensing capacitor Cs through the modulation capacitor Cc when it is turned on;

[0092] A frequency divider, used for performing frequency division processing on the source clock signal to output a frequency-divided clock signal;

[0093] And a spread spectrum clock generator CSS is connected to the output end of the frequency divider and is used to control the first switch SW1 and the second switch SW2 to be alternately opened and closed according to the divided clock signal.

[0094] It can be seen that the charging and discharging module 110 uses the spread spectrum clock generator CSS to change the divided clock signal using its own random sequence to generate an alternating control signal with an average frequency less than the source clock signal, that is, a signal with positive and negative random swings, and then uses the alternating control signal to control the first switch SW1 and the second switch SW2 to be alternately turned on and off, thereby realizing alternating control of charging and discharging of the inductive capacitor Cs.

[0095] It can be seen that the spread spectrum clock generator CSS provides a beating clock frequency to control the first switch SW1 and the second switch SW2 to alternately open and close, thereby realizing the alternate charging and discharging of the inductive capacitor Cs, which can reduce the EMI caused by the fixed clock frequency and effectively reduce the peak value of electromagnetic radiation. In addition, the charging and discharging module 110 of the above-mentioned structure has the advantages of simple structure and low manufacturing cost.

[0096] In some examples, in order to reduce the complexity of generating the alternating control signal and make the charging time and discharging time of the sensing capacitor Cs approach or be the same to further improve the accuracy of the sampling result, the above average frequency can be set to half of the source clock signal.

[0097] In some embodiments, please refer to Figure 2In order to improve the circuit integration and avoid electromagnetic interference or other interference caused by the external source clock signal, the capacitance detection unit provided in the embodiment of the present invention may also include an HSI clock generator. Based on this, the source clock signal mentioned in this article can be provided by the HSI clock generator. In some examples, the maximum operating frequency of the HSI clock generator can be 16MHz, so as to provide clock signals with more frequencies according to actual application requirements.

[0098] In some embodiments, in order to effectively simplify the structure of the current modulation module 120 and reduce the manufacturing cost, and to improve the stability and accuracy of the high-level signal and the low-level signal, the embodiment of the present invention further provides an implementation scheme of the current modulation module 120, please continue to refer to Figure 2 In addition to the modulation capacitor Cc, the current modulation module 120 also includes:

[0099] a modulation current source Im, connected to one end of the modulation capacitor Cc connected to the second switch SW2, and used for charging the modulation capacitor Cc when the low level signal is output;

[0100] A switch circuit, comprising a third switch SW3 connected in series between the modulation capacitor Cc and the modulation current source Im;

[0101] A comparator CMP, a positive input terminal connected to a reference voltage VREF, an inverting input terminal connected to one end of the modulation capacitor Cc connected to the second switch SW2, for outputting the high level signal when the voltage of the modulation capacitor Cc is lower than the reference voltage VREF, and outputting the low level signal when the voltage of the modulation capacitor Cc is higher than the reference voltage VREF;

[0102] and a latch, whose signal input end is connected to the output end of the comparator CMP, whose signal output end is respectively connected to the switch circuit and the sampling module 130, and whose clock input end is used to connect the source clock signal; the latch is used to control the third switch SW3 to be turned on and the sampling module 130 to start counting when the comparator CMP outputs the high level signal, and to control the third switch SW3 to be turned off and the sampling module 130 to pause counting when the comparator CMP outputs the low level signal.

[0103] Correspondingly, the other end of the modulation capacitor Cc is grounded.

[0104] Combined with the working principle described above, it can be known that the current modulation module 120 compares the reference voltage VREF and the voltage of the modulation capacitor Cc by using the comparator CMP, that is, when the reference voltage VREF is higher than the voltage of the modulation capacitor Cc, the comparator CMP will output a high-level signal, and when the reference voltage VREF is lower than the voltage of the modulation capacitor Cc, the comparator CMP will output a low-level signal. Among them, after the high-level signal is transmitted to the latch and latched by the latch, the latch will enable the sampling module 130 to count, and at the same time control the third switch SW3 to be turned on so that the modulation current source Im and the modulation capacitor Cc are connected, thereby charging the modulation capacitor Cc. After the low-level signal is transmitted to the latch and latched by the latch, the latch will enable the sampling module 130 to suspend counting, and at the same time control the third switch SW3 to be turned off so that the modulation current source Im and the modulation capacitor Cc are disconnected, thereby stopping charging the modulation capacitor Cc.

[0105] It can be seen that the current modulation module 120 adopting the above structure not only has the advantages of simple structure and low manufacturing cost, but also configures a latch at the output end of the comparator CMP, and uses the output of the latch to control the on-off of the third switch SW3 and the counting of the acquisition module. Compared with directly using the output of the comparator CMP as control, it can improve the stability of the output signal, avoid signal turbulence and affect the stability and accuracy of the on-off control of the third switch SW3 and the counting control of the acquisition module, which is beneficial to further improve the capacitance detection accuracy.

[0106] In some embodiments, in order to further ensure that complete sampling can be completed during the sampling process, the embodiment of the present invention further improves the structure of the current modulation module 120 on the basis of the previous embodiment, that is, please continue to refer to Figure 2 The current modulation module 120 may further include a compensation current source Ic; the compensation current source Ic is connected to one end of the modulation capacitor Cc connected to the second switch SW2, and is used to charge and compensate the modulation capacitor Cc.

[0107] It is understandable that the compensation current source Ic can be in the on state whether sampling or not sampling, and can continuously charge and supplement the modulation capacitor Cc. Therefore, by adding the compensation current source Ic in the current modulation module 120, it is realized that the compensation current source Ic can charge and compensate the modulation capacitor Cc whether in the sampling process or the non-sampling process, which can avoid that when the sensing capacitor Cs is large, the modulation capacitor Cc discharges too fast and too much, and there is a large amount of charge transfer, which leads to the time required for the modulation capacitor Cc to charge to the above-mentioned reference voltage VREF to be extended, and may even exceed the time required for sampling, and thus cannot complete the complete sampling within the sampling time limited by the sampling process.

[0108] However, it should be noted that the current of the compensation current source Ic is smaller than the current of the modulation current source Im, which is equivalent to the role of the bias capacitor, and is used to prevent the modulation capacitor Cc from being charged too long when it is discharged too much. In addition, the size of the compensation current source Ic can be selected according to actual application requirements and related technologies. For example, if it is necessary to further improve the sensitivity of capacitance detection, a smaller compensation current source Ic can be selected; if the equivalent parasitic capacitance of the capacitance detection unit is large but the inductive capacitance Cs is small, a larger compensation current source Ic can be selected.

[0109] However, in order to balance the influence of capacitance detection sensitivity and equivalent parasitic capacitance and ensure the counting validity of the sampling module 130, in some embodiments, the embodiments of the present invention further provide a solution for determining the size of the compensation current source Ic, that is, the appropriate compensation current source Ic and modulation current source Im can be obtained by the following formula:

[0110]

[0111] In the above formula, COUNT is the total value above, η TIM-HSI is the number of cycles of the source clock signal contained in the sampling duration controlled in the sampling module 130, that is, Among them, t is the sampling time, F HSI is the frequency of the source clock signal, F css is the average frequency of the alternating control signal generated by the spread spectrum clock generator CSS, C sd is the capacitance value of the sensing capacitor Cs, C pd is the capacitance value of the equivalent parasitic capacitance, VREF d is the voltage value of the reference voltage VREF, I md is the current value of the modulation current source Im, I cd is the current value of the compensation current source Ic. It can be seen that the value of COUNT cannot be greater than η TIM-HSI And it cannot be less than 0, so the total value cannot be greater than the number of cycles of the incoming clock, nor can it be a negative value. Among them, since the circuit structure of the circuit detection unit is determined, the values ​​of its equivalent parasitic capacitance and inductive capacitance Cs can be known through relevant technologies. Therefore, the value of COUNT can be estimated by the above formula and the constraints of COUNT. If the value of COUNT is greater than n TIM-HSI This indicates that I needs to be increased appropriately. md or I cd If the value of COUNT is less than 0, it means that I needs to be appropriately reduced. ca , you can ignore I md The adjustment range can be determined according to actual needs, as long as the COUNT value cannot be greater than n TIM-HSI And it cannot be less than 0.

[0112] It can be seen that the final I md and I cd Taking into account the capacitance value of the sensing capacitor Cs, the capacitance value of the equivalent parasitic capacitance, the total value, the frequency of the source clock signal and the average frequency of the alternating control signal generated by the spread spectrum clock generator CSS, the final selected compensation current source Ic and modulation current source Im can balance the capacitance detection sensitivity and the influence of the equivalent parasitic capacitance, while ensuring the counting validity of the sampling module 130, thereby improving the stability of capacitance detection.

[0113] In addition, the above cd , or md and I cd The adjustment may be performed before the capacitance detection unit is applied to the product, or may be readjusted according to actual needs during the application stage, which is not limited in the embodiments of the present invention.

[0114] In some embodiments, to further reduce the impact of equivalent parasitic capacitance in the entire circuit system, please continue to refer to Figure 2 The embodiment of the present invention also provides a further solution, that is, the inductive capacitor Cs is formed by a copper foil inductive disk arranged on a circuit board, and the copper foil inductive disk is surrounded by a copper clad connected to a shielded motor. Accordingly, the capacitance detection unit further includes a shielding buffer BUFF1, which is connected in series between the copper foil inductive disk and the copper clad to maintain the voltage of the copper foil inductive disk consistent with the voltage of the copper clad.

[0115] It can be seen that by adding a shielding buffer BUFF1, the voltage of the copper foil sensing disk and the copper cladding BED is kept consistent, that is, there is no potential difference between the copper foil sensing disk and the copper cladding, which can avoid the equivalent parasitic capacitance (equivalent to Figure 2 Capacitor Cp in the copper foil induction plate and copper cladding (equivalent to Figure 2 The charge in the capacitor between the shield electrode BEO in the sensor will flow out or flow to other conductors with a path, thus affecting the sampling accuracy. Because there is no potential difference between the copper foil sensing disk and the copper cladding, even if there are water droplets on the copper cladding, the capacitance caused by the water droplets will be eliminated, thus achieving a waterproof effect.

[0116] In some embodiments, to further improve the capacitance detection accuracy, please continue to refer to Figure 2The embodiment of the present invention also provides a corresponding optimization solution, that is, the switch circuit may further include a fourth switch SW4; and the current modulation module 120 may further include a charging buffer BUFF2. The input end of the charging buffer BUFF2 is connected to the reference voltage VREF, and the output end is connected to the modulation current source Im through the fourth switch SW4.

[0117] Correspondingly, the latch is further used to control the fourth switch SW4 to be turned off when the comparator CMP outputs the high level signal, and to control the fourth switch SW4 to be turned on when the comparator CMP outputs the low level signal.

[0118] It can be seen that by adding the fourth switch SW4 and the charging buffer BUFF2, the terminal voltage of the modulation current at the switching moment of the third switch SW3 can be maintained at the reference voltage VREF, which can effectively prevent the modulation current source Im from charging too much charge to the modulation capacitor Cc at the switching moment of the third switch SW3, thereby affecting the capacitance detection accuracy.

[0119] In some embodiments, in order to further improve the capacitance detection accuracy, the present invention also provides an implementation scheme of the sampling module 130, that is, please continue to refer to Figure 2 , the sampling module 130 includes:

[0120] A counter, whose clock input terminal is used to access the source clock signal, whose enable terminal is connected to the signal output terminal of the latch, and whose count output terminal is used to output the total value;

[0121] And a timer, whose clock input end is used to access the source clock signal, the enable end is used to access the sampling trigger signal, and the control output end is used to access the control input end of the counter; the timer is used to clear the count value of the counter when receiving the sampling trigger signal, and control the counter to start counting, and control the counter to stop counting after setting the sampling time, so that the counter outputs the total value.

[0122] Combining the above working principle, it can be known that, on the one hand, the sampling module 130 uses a counter to count the number of cycles of the source clock signal, so as to determine the duration of the high-level signal later; and the counting enable of the counter is triggered by the latch latching the high-level signal. On the other hand, the sampling module 130 controls the start of sampling when the timer is triggered by the sampling trigger signal, and controls the end of sampling when the timing duration of the timer reaches the set sampling duration after the sampling starts, and ends the counting of the counter. At this time, the count value output by the counter is the total value in this round of sampling process.

[0123] It can be seen that the sampling module 130 using the above structure has the advantages of simple structure and low manufacturing cost. In addition, since the clock signal used by the counter and timer is consistent with the clock signal sampled by the charge and discharge module 110, the timing consistency between the three can be guaranteed, thereby improving the accuracy of the total value, thereby improving the capacitance detection accuracy.

[0124] In some embodiments, in order to further improve the capacitance detection accuracy, the present invention also provides a further optimized sampling module 130, please continue to refer to Figure 2 , the sampling module 130 may further include:

[0125] The pre-charge buffer BUFF3 has an input terminal connected to the reference voltage VREF, and an output terminal connected to the inverting input terminal of the comparator CMP through a fifth switch SW5; the pre-charge buffer BUFF3 is used to stabilize the voltage of the modulation capacitor Cc at the reference voltage VREF when sampling starts.

[0126] Combined with the above working principle, it can be known that at the beginning of sampling, the counter is first cleared and the voltage of the modulation capacitor Cc is stabilized at the reference voltage VREF through the pre-charge buffer BUFF3 before the sampling process is officially started. Based on the above-mentioned reference voltage VREF as the basis for controlling the charging timing of the modulation capacitor Cc, it can be avoided that the voltage of the modulation capacitor Cc is too low or too high at the beginning of sampling, which affects the output result of the comparator CMP, so that the charging time of the modulation capacitor Cc tends to or is equal to the discharge time of the modulation capacitor Cc to the inductive capacitor Cs, which can improve the counting accuracy.

[0127] In some embodiments, to reduce circuit power consumption, refer to Figure 3 , Figure 3 is a schematic diagram of a circuit structure of another capacitance detection unit provided in an embodiment of the present invention. The capacitance detection unit may further include a low power consumption trigger module 140. The low power consumption trigger module 140 includes:

[0128] Low speed clock source LSI;

[0129] And a timing trigger, whose clock input end is connected to the low-speed clock source LSI, and whose trigger output end is connected to the timer, is used to output the sampling trigger signal to the timer.

[0130] In the above, using the low-speed clock source LSI to provide a clock signal for the timing trigger can reduce the energy consumption of the clock source, and using the timing trigger to trigger the timer to start can avoid the timer starting all the time and generating more energy consumption. In some examples, the maximum operating frequency of the low-speed clock source LSI can be 32KHz.

[0131] Combined with the working principle described above, it can be seen that after the low-power trigger module 140 is added, the sampling trigger signal of the timer in the sampling module 130 is provided by the timing trigger. It can be understood that the start of each sampling process is controlled by the timing trigger. As long as the timing trigger sends a sampling trigger signal to the timer, the capacitance detection part E including the sensing capacitor Cs, the charging and discharging module 110, the current modulation module 120 and the sampling module 130 will enter the sampling process to complete the sampling.

[0132] Based on the previous embodiment, to further reduce the power consumption of the circuit, please continue to refer to Figure 3 , the capacitance detection unit 100 provided in the embodiment of the present invention may further include:

[0133] A low-dropout linear regulator LDO, whose enable terminal is connected to the trigger output terminal of the timing trigger, and whose input terminal is connected to a DC power supply; the low-dropout linear regulator LDO is used to provide working power for the charging and discharging module 110, the current modulation module 120 and the sampling module 130. It can be understood that it is used to provide working power for the capacitance detection part E in the capacitance detection unit 100.

[0134] Correspondingly, the timing trigger is also used to control the low voltage dropout linear regulator LDO to supply power when the sampling trigger signal is output, and is used to control the low voltage dropout linear regulator LDO to stop supplying power when sampling is finished.

[0135] Combined with the working principle above, it can be known that the timing trigger can not only trigger the timer to start the sampling process, but also trigger the low-dropout linear regulator LDO to enter the power supply mode. When the timer ends the sampling process, the timing trigger can receive the corresponding feedback signal, and then control the low-dropout linear regulator LDO to stop supplying power.

[0136] It can be seen that by adding a low-dropout linear regulator LDO to provide working power for the capacitance detection part E in the capacitance detection unit, these circuit devices can have better anti-interference effect during the sampling process. On this basis, the working state of the low-dropout linear regulator LDO is further controlled by a timing trigger, and the power supply of the above circuit devices can be turned off when sampling is not required, which is conducive to further reducing the power consumption of the circuit.

[0137] In the above, the power supply output by the low voltage drop linear regulator LDO can be 1.8V, but is not limited thereto. In some embodiments, to further reduce circuit power consumption and improve sampling sensitivity, please continue to refer to Figure 3 The embodiment of the present invention further proposes a further improvement scheme for the low power consumption trigger module 140, namely:

[0138] The low power consumption trigger module 140 further includes a counting comparator connected to the counting output terminal of the counter, and the counting comparator is used to determine whether to send a wake-up signal according to the total value output by the counter and a set value range.

[0139] Correspondingly, the capacitance detection unit 100 also includes a control module (not shown), the signal input end of the control module is connected to one end of the counting comparator for outputting the wake-up signal, and the control end is connected to the timing trigger; the control module is used to increase the trigger frequency of the timing trigger when the wake-up signal is received, and reduce the trigger frequency of the timing trigger when the wake-up signal is not received within a set time period.

[0140] The above-mentioned numerical range can be set according to the count value range corresponding to the capacitance value of the sensing capacitor Cs when the capacitance value does not change, wherein, when the total value output by the counter is greater than the maximum value of the numerical range, it indicates that the capacitance value of the sensing capacitor Cs has changed, at which time the counting comparator will send a wake-up signal, the control module will be awakened, and then the control module will calculate the capacitance value based on the total value and determine the current touch position based on the capacitance value. When the above-mentioned total value is less than the minimum value of the numerical range, it indicates that the sensing capacitor Cs or the capacitance sampling part may have a fault, at which time the counting comparator will also send a wake-up signal, the control module will be awakened, and then the control module will calculate the abnormal capacitance value based on the total value, and at this time, an alarm signal can be further sent to notify relevant personnel to conduct troubleshooting.

[0141] It can be seen that by adding a counting comparator and a control module, the counting comparator is used to compare the total value with the set value range, and then determine whether to output a wake-up signal to wake up the control module based on the comparison result. In this way, the control module can be in sleep mode when it does not need to be woken up, thereby reducing the overall circuit power consumption. When the control module needs to be woken up, the triggering efficiency of the timing trigger can be increased, so that the sampling module 130 can sample at a higher frequency, which can improve the sampling sensitivity.

[0142] Based on the above embodiment, in some embodiments, to further improve the capacitance detection sensitivity and touch detection accuracy and reduce the sampling energy consumption, please continue to refer to Figure 3 The capacitance detection unit provided in the embodiment of the present invention may be provided with a plurality of inductive capacitors Cs (the plurality of inductive capacitors are not shown in the figure). Based on this, the capacitance detection unit 100 may further include:

[0143] The multiple-way sorting / merging switch S1 is connected in series between the multiple sensing capacitors Cs and the first switch SW1 , and the multiple switch channels of the multiple-way sorting / merging switch S1 are connected one by one to the multiple sensing capacitors Cs respectively.

[0144] Correspondingly, the control module is also used to control the multiple switch channels in the multi-way sorting / merging switch S1 to be turned on one by one when the wake-up signal is received, and to control the multiple switch channels in the multi-way sorting / merging switch S1 to be combined and turned on when the wake-up signal is not received within the set time.

[0145] It can be seen that for the scenario where there are multiple sensing capacitors Cs, by adding a multi-way sorting / merging switch S1, the control module can determine the scanning detection method of the sensing capacitor Cs through the multi-way sorting / merging switch S1 according to the change of the sensing capacitor Cs. For example, when the control module receives a wake-up signal, it means that the sensing capacitor Cs has changed. In order to find out which sensing capacitors Cs have changed in capacitance, the multiple switch channels in the multi-way sorting / merging switch S1 are controlled to be turned on one by one to perform polling scans on all the sensing capacitors Cs. When the control module has not received a wake-up signal within the set time, it means that the sensing capacitor Cs has not changed. At this time, in order to save circuit energy consumption, the control module controls the multiple switch channels in the multi-way sorting / merging switch S1 to be combined and turned on, and the outputs of all the sensing capacitors Cs are combined into one to perform a combined scan to determine whether the capacitance has changed, and then switch to a polling scan when it has changed.

[0146] Among them, the combined scan only needs to be scanned once, while the polling scan needs to be scanned multiple times. It can be seen that when the sensing capacitance Cs has not changed, the combined scan method is not only suitable for the current scene, but also can reduce the energy consumption required for sampling. When the sensing capacitance Cs changes, switching to the polling scan method can accurately determine whether each sensing capacitance Cs has changed, thereby improving the capacitance detection sensitivity and touch detection accuracy.

[0147] In some embodiments, on the basis that the capacitance detection unit provided in the embodiment of the present invention does not have a counting comparator, in order to make the capacitance detection unit provided in the embodiment of the present invention also applicable to the scenario of multiple sensing capacitors Cs, that is, the capacitance detection unit provided in the embodiment of the present invention can be provided with multiple sensing capacitors Cs, based on this, the capacitance detection unit can also include:

[0148] A multiple-way sorting / merging switch S1 is connected in series between the plurality of sensing capacitors Cs and the first switch SW1, and a plurality of switch channels of the multiple-way sorting / merging switch S1 are connected one by one with the plurality of sensing capacitors Cs respectively;

[0149] and a control module, for controlling the multiple switch channels in the multi-way sorting / merging switch S1 to be turned on one by one when the total value is not within the set value range, and for controlling the multiple switch channels in the multi-way sorting / merging switch S1 to be turned on in combination when the total value is within the value range.

[0150] The relevant interpretation of the above numerical range and the control principle of the control module on the multi-way sorting / merging switch S1 can be found in the above related records and will not be elaborated here.

[0151] It can be seen that on the basis that the capacitance detection unit does not have a counting comparator, for the scenario in which multiple sensing capacitors Cs are provided, the function of the counting comparator can be transferred to the control module, that is, the control module can control the working mode of the multi-way sorting / merging switch S1 according to the total value and the value range, and then when all the sensing capacitors Cs have not changed, the multiple switch channels in the multi-way sorting / merging switch S1 can be controlled to be combined and turned on, so as to reduce sampling energy consumption and improve capacitance detection sensitivity and touch detection accuracy.

[0152] Corresponding to the embodiment of the capacitance detection unit, an embodiment of the present invention further provides a touch control device, which includes the capacitance detection unit 100 in any of the above embodiments of the present invention.

[0153] Corresponding to the embodiment of the capacitance detection unit, an embodiment of the present invention further provides an interaction device, which includes the capacitance detection unit 100 in any of the above embodiments of the present invention.

[0154] For the products involved in the interactive device, please refer to the relevant records above, and no further description is given here. However, in order to facilitate understanding of the practical application of the capacitance detection unit, the following is an exemplary description of the application scenario using the interactive device as an electronic door lock:

[0155] At this time, the capacitance detection unit will be applied to the detection of the touch keyboard of the electronic door lock, and lower power consumption is required in this scenario. Therefore, when the capacitance detection unit is powered on, the control module can first configure a shorter sampling interval, such as 1ms, and when the sensing capacitor Cs has multiple channels, it will periodically poll all the channels of the sensing capacitor Cs and output the corresponding total value. If it is determined by the total value that the capacitance has not changed within the set time, for example, 1min, the control module will configure a longer sampling interval, such as 250ms, so that the entire capacitance detection unit enters a low power mode. In low power mode, the capacitance detection unit will sample regularly in a combined scanning manner and determine whether the sensing capacitor Cs has changed. This process does not require the participation of the control module (when the capacitance detection unit includes a counting comparator). If it is found that the capacitance has changed, the counting comparator sends a wake-up signal to the control module, so that the entire capacitance detection unit enters the wake-up mode. At this time, the control module will configure a shorter sampling interval, such as 1ms, and sample regularly in a polling scanning manner. After the sampling is completed, the control module can calculate the size of the capacitance value according to the total value, and judge whether there is a finger pressed on the touch keyboard and the position where the finger is pressed by the capacitance value.

[0156] In the above, the capacitance detection principle of the touch device and the interactive device can refer to the relevant description of the capacitance detection unit in any embodiment of the present invention, and will not be described in detail here.

[0157] It is worth noting that the technical features or technical solutions in any of the above embodiments of the present invention can be combined or combined with each other as long as there is no contradiction in the combination or combination.

[0158] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A capacitance detection unit, characterized in that: include: Sensing capacitor, used to detect the capacitance change at the sensing electrode; A charging and discharging module, used to control the alternating charging and discharging of the sensing capacitor according to a source clock signal during the sampling process; A current modulation module, comprising a modulation capacitor; the current modulation module is used to: during the charging process of the induction capacitor, control the modulation capacitor to charge the induction capacitor; when the voltage of the modulation capacitor is lower than the reference voltage, output a high level signal, and charge the modulation capacitor until the voltage of the modulation capacitor is higher than the reference voltage; and when the voltage of the modulation capacitor is higher than the reference voltage, output a low level signal; and a sampling module, which is used to control the start and end of the sampling process, and in the sampling process, when the current modulation module outputs a high-level signal, cumulatively count the number of cycles of the source clock signal until the current modulation module outputs the low-level signal, so as to obtain a total value in the sampling process; the total value is used to characterize the capacitance change of the inductive capacitor.

2. The capacitance detection unit according to claim 1, characterized in that: The charging and discharging module comprises: A first switch, one end of which is grounded and the other end of which is connected to the inductive capacitor, and is used to discharge the inductive capacitor when it is turned on; A second switch, one end of which is connected to the induction capacitor and the other end of which is connected to the modulation capacitor, and is used to charge the induction capacitor through the modulation capacitor when it is turned on; A frequency divider, used for performing frequency division processing on the source clock signal to output a frequency-divided clock signal; and a spread spectrum clock generator connected to the output end of the frequency divider, for controlling the first switch and the second switch to be alternately disconnected and turned on according to the divided clock signal.

3. The capacitance detection unit according to claim 2, characterized in that: The current modulation module also includes: a modulation current source connected to one end of the modulation capacitor connected to the second switch, and used for charging the modulation capacitor when the low level signal is output; A switch circuit, comprising a third switch connected in series between the modulation capacitor and the modulation current source; A comparator, wherein a positive input terminal is connected to the reference voltage, an inverting input terminal is connected to one end of the modulation capacitor connected to the second switch, and is used to output the high level signal when the voltage of the modulation capacitor is lower than the reference voltage, and output the low level signal when the voltage of the modulation capacitor is higher than the reference voltage; and a latch, whose signal input end is connected to the output end of the comparator, whose signal output end is respectively connected to the switch circuit and the sampling module, and whose clock input end is used to connect to the source clock signal; the latch is used to control the third switch to be turned on and the sampling module to start counting when the comparator outputs the high level signal, and to control the third switch to be turned off and the sampling module to suspend counting when the comparator outputs the low level signal; The other end of the modulation capacitor is grounded.

4. The capacitance detection unit according to claim 3, characterized in that: The current modulation module also includes: A compensation current source is connected to one end of the modulation capacitor connected to the second switch, and is used to charge and compensate the modulation capacitor.

5. The capacitance detection unit according to claim 3 or 4, characterized in that: The switch circuit further includes a fourth switch; and the current modulation module further includes: a charging buffer, wherein an input end of the charging buffer is connected to the reference voltage, and an output end of the charging buffer is connected to the modulation current source through the fourth switch; The latch is further used to control the fourth switch to be turned off when the comparator outputs the high level signal, and to control the fourth switch to be turned on when the comparator outputs the low level signal.

6. The capacitance detection unit according to claim 3, characterized in that: The sampling module comprises: A counter, whose clock input terminal is used to access the source clock signal, whose enable terminal is connected to the signal output terminal of the latch, and whose count output terminal is used to output the total value; And a timer, whose clock input end is used to access the source clock signal, the enable end is used to access the sampling trigger signal, and the control output end is used to access the control input end of the counter; the timer is used to clear the count value of the counter when receiving the sampling trigger signal, and control the counter to start counting, and control the counter to stop counting after setting the sampling time, so that the counter outputs the total value.

7. The capacitance detection unit according to claim 6, characterized in that: The sampling module also includes: A pre-charge buffer, whose input terminal is connected to the reference voltage, and whose output terminal is connected to the inverting input terminal of the comparator through a fifth switch; the pre-charge buffer is used to stabilize the voltage of the modulation capacitor at the reference voltage when sampling starts.

8. The capacitance detection unit according to claim 1, characterized in that: The inductive capacitor is formed by a copper foil inductive disk arranged on a circuit board, and the copper foil inductive disk is surrounded by a copper clad connected to a shielded motor; the capacitance detection unit also includes a shielding buffer, which is connected in series between the copper foil inductive disk and the copper clad, and is used to maintain the voltage of the copper foil inductive disk consistent with the voltage of the copper clad.

9. The capacitance detection unit according to claim 6, characterized in that: Also included is a low-power trigger module; The low power consumption trigger module comprises: Low speed clock source; And a timing trigger, whose clock input end is connected to the low-speed clock source, and whose trigger output end is connected to the timer, is used to output the sampling trigger signal to the timer.

10. The capacitance detection unit according to claim 9, characterized in that: The low power consumption trigger module further includes a counting comparator connected to the counting output terminal of the counter, and the counting comparator is used to determine whether to send a wake-up signal according to the total value output by the counter and a set value range; The capacitance detection unit also includes a control module, a signal input end of the control module is connected to an end of the counting comparator for outputting the wake-up signal, and the control end is connected to the timing trigger; the control module is used to increase the trigger frequency of the timing trigger when the wake-up signal is received, and reduce the trigger frequency of the timing trigger when the wake-up signal is not received within a set time.

11. The capacitance detection unit according to claim 9, characterized in that: Also includes: A low-voltage dropout linear regulator, whose enable end is connected to the trigger output end of the timing trigger and whose input end is connected to a DC power supply; the low-voltage dropout linear regulator is used to provide working power for the charging and discharging module, the current modulation module and the sampling module; The timing trigger is also used to control the low voltage difference linear regulator to supply power when the sampling trigger signal is output, and to control the low voltage difference linear regulator to stop supplying power when sampling is finished.

12. The capacitance detection unit according to claim 10, characterized in that: The inductive capacitor is provided with a plurality of capacitors; the capacitance detection unit further comprises: A multi-way sorting / merging switch is connected in series between the plurality of sensing capacitors and the first switch, wherein the plurality of switch channels of the multi-way sorting / merging switch are respectively connected one by one with the plurality of sensing capacitors; The control module is also used to control multiple switch channels in the multi-way sorting / merging switch to be turned on one by one when the wake-up signal is received, and to control multiple switch channels in the multi-way sorting / merging switch to be turned on in combination when the wake-up signal is not received within the set time period.

13. The capacitance detection unit according to claim 1, characterized in that: The inductive capacitor is provided with a plurality of capacitors; the capacitance detection unit further comprises: A multi-way sorting / merging switch is connected in series between the plurality of sensing capacitors and the first switch, wherein the plurality of switch channels of the multi-way sorting / merging switch are respectively connected one by one with the plurality of sensing capacitors; and a control module, which is used to control the multiple switch channels in the multi-way sorting / merging switch to be turned on one by one when the total value is not within the set value range, and to control the multiple switch channels in the multi-way sorting / merging switch to be turned on in combination when the total value is within the value range.

14. A touch device, characterized in that: The invention comprises the capacitance detection unit according to any one of claims 1 to 13.

15. An interactive device, characterized in that: The invention comprises the capacitance detection unit according to any one of claims 1 to 13.

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