TWI832649B - Self-calibration contact-sensing device and electronic device using the same - Google Patents

Abstract

A self-calibration contact-sensing device includes: a sense pad; transistors T1 and T2, the emitter of the transistor T2connected to the base of the transistor T1 via a switch; a multiplexer, selectively outputting the electronic signal sensed by the sense pad, when user touching the sense pad, to one of the bases of the transistors T1 and T2; and a micro-controller. The micro-controller initially turns off the switch and makes the multiplexer output the sensed signal to the base of the transistor T1. When the current flowing through the transistor T1 is more than a threshold, the setting for detection of user’s touch is completed. Otherwise, when the current flowing through the transistor T1 is not more than the threshold, the micro-controller turns of the switch and makes the multiplexer output the sensed signal to the base of the transistor T2.

Description

Self-correcting contact sensing device and electronic device configured with the contact sensing device

The present invention relates to a sensing device, in particular to a contact sensing device that can detect human contact and self-correct, and an electronic device using the contact sensing device.

Energy-saving sensors (Presence Sensor) on the market mainly detect the presence or absence of a target object or whether it has moved through changes in infrared rays emitted by the object itself. There is also an energy-saving sensor based on microwave Doppler radar to detect movement of objects. If the above two are applied to electronic devices such as computers, they need to use algorithms and corresponding databases to identify whether the user is in front of the computer. Therefore, the application of energy-saving sensors in computer devices requires more design considerations and material costs.

In addition, when energy-saving sensors are used to save energy in electronic devices such as computers, after the user leaves the computer, due to the limitations of the detection operation mechanism of the energy-saving sensor, it will take a while to determine that the user has left. computer, later Put the computer into power saving mode. However, considering the energy-saving applications of electronic devices such as computers, the main purpose is to automatically enter the power-saving mode as soon as the user leaves the computer within a short period of time, and to ensure that the user's hand touches the sensor before returning to the computer. The computer can be quickly woken up when the test pad is ready for work.

In view of this, the present invention provides a self-correcting touch sensing device and an electronic device configured with the touch sensing device. The contact sensing device can self-correct and adjust in response to different users, so as to successfully set up corresponding settings for contact detection of different users. After the setting is completed, the contact sensing device senses the user's contact and can quickly determine whether the user leaves the electronic device, so as to notify the electronic device to enter the power saving mode as soon as possible, and before the user returns to the electronic device, the hand touches the sensing pad Quickly wake up electronic devices when getting ready for work.

One embodiment of the present invention provides a self-correcting contact sensing device, including: a sensing pad, a first detection device, a second detection device, a multiplex selector, a first switch, and a microcontroller. The sensing pad is used to sense the user's human body electrical signals (such as human body current, voltage, etc.). The first detection device is configured to amplify the first electrical signal and output the first amplified electrical signal when receiving a first electrical signal; the second detection device is configured to amplify the second electrical signal when receiving a second electrical signal. signal and output a second amplified electrical signal. A multiplex selector, coupled to the sensing pad, is configured to select, based on the selection signal, to use the human body electrical signal as the first electrical signal and output it to the first detection device, or to use the human body electrical signal as the second electrical signal to output the second electrical signal. Detection device. The first switch, coupled The first detection device and the second detection device are turned on or off according to the control signal. A microcontroller is coupled to the first detection device and the multiplexer. Among them, the microcontroller, when the first amplified electrical signal is greater than a critical value, determines that the sensing pad is in contact with a human body; if the first amplified electrical signal is not greater than the critical value, the microcontroller outputs a selection signal to control multiplexing selection. The device outputs the human body electrical signal as the second electrical signal to the second detection device, and at the same time outputs a control signal to control the first switch to conduct, so as to input the second amplified electrical signal as the first electrical signal to the first detection device.

In some embodiments, the contact sensing device further includes a third detection device that amplifies the third electrical signal and outputs a third amplified electrical signal when receiving a third electrical signal; and a second switch coupled to The second detection device and the third detection device are turned on or off according to the control signal. Among them, the multiplex selector can further select the human body electrical signal as the third electrical signal to output to the third detection device according to the selection signal. When the multiplex selector selects the human body electrical signal to be output to the second detection device as the second electrical signal, and at the same time, when the value of the first amplified electrical signal is not greater than the critical value, the microcontroller uses the selection signal to cause the multiplex selector to Changed to output the human body electrical signal to the third detection device as the third electrical signal; and, the controller further turns on the above-mentioned second switch through the control signal, so that the third amplified electrical signal of the third detection device The second electrical signal is supplied to the second detection device, and the second amplified electrical signal of the second detection device is supplied to the first detection device as the first electrical signal.

In some embodiments, the contact sensing device further includes an electrical signal sensing circuit coupled to the first sensing device and the microcontroller for sensing the value of the first amplified electrical signal.

In some embodiments, the first detection device, the second detection device, and the third detection device in the contact sensing device are a first BJT (BiJT) transistor, a second BJT transistor, and a third BJT transistor. In addition, the emitter of the third BJT transistor is coupled to the base of the second BJT transistor through the second switch, and the emitter of the second BJT transistor is coupled to the base of the first BJT transistor through the first switch; Each output of the multiplexer is coupled to the base of the first BJT transistor to the third BJT transistor respectively.

In some embodiments, the contact sensing device further includes a power supply device and an indicating device. The power supply device couples the first BJT transistor to the collector of the third BJT transistor and the emitter of the first BJT transistor. The indicating device is coupled to the first detection device, and when the value of the first amplified electrical signal is greater than the above-mentioned threshold value, it is used to indicate that the sensing pad is in contact with a human body. The indicating device may be a light emitting diode device.

In some embodiments, the contact sensing device further includes a third switch and a fourth switch. The third switch is coupled to the collector of the second BJT transistor and the power supply device, and has the same on/off state as the first switch. The fourth switch is coupled to the collector of the third BJT transistor and the power supply device, and has the same on/off state as the second switch.

Another embodiment of the present invention provides an electronic device equipped with the aforementioned self-correcting contact sensing device and a processor. Wherein, after the contact sensing device determines the on/off state of the above-mentioned switch and the output of the above-mentioned multiplex selector, when the microcontroller of the contact sensing device determines that there is no human contact with the sensing pad, it notifies the processor and processes The device drives the electronic device into a power saving mode.

In some embodiments, the aforementioned electronic device is a notebook computer. In addition, the sensing pad is one or more metal sheets or metal coatings, which are disposed on the same plane as the keyboard of the notebook computer.

10:Laptop

101: Processor (CPU)

20: Self-calibrating contact sensing device

200: Sensing pad

201-204: First to fourth detection devices

205:Multiple selector

206: Microcontroller (μC)

207:Reading device

208:Indicating device

T1-T4:BJT transistor

SS: select signal

SW1-SW6: switch

Sc1-Sc3: control signal

R: resistor

CP: comparator

EN: enable signal

A-D: Output of multiplexer

Vout: the output of the reading device

VR: power supply device

Figure 1 is a schematic diagram of an electronic device according to an embodiment of the present invention.

Figure 2 is a schematic block diagram of a self-correcting contact sensing device according to an embodiment of the present invention.

In order to make the above-mentioned objects, features and advantages of the present invention more clearly understandable, preferred embodiments are given below and described in detail with reference to the accompanying drawings.

Figure 1 is a block diagram of an electronic device 10 according to an embodiment of the present invention.

As shown in FIG. 1 , an electronic device is configured with a self-correcting contact sensing device disclosed in the present invention. The electronic device may be a notebook computer, a laptop computer, a desktop computer, etc. electronic products. In this embodiment, the electronic device is, for example, a notebook computer, but it is not limited thereto. In this embodiment, the notebook computer 10 will be taken as an example for description. The notebook computer 10 includes: a host system (not shown) controlled by a processor (CPU) 101, and a self-correcting contact sensing device 20.

The self-correcting contact sensing device 20 may include, but is not limited to, Including: sensing pad 200, first detection device 201, second detection device 202, third detection device 203, fourth detection device 204, multiplex selector 205, switch SW1~SW6, and micro control Device (μC) 206. Below, each component of the self-correcting contact sensing device 20 and their connection relationships will be described. In addition, the self-correcting contact sensing device 20 may further include a power supply device VR, such as a voltage regulator.

The sensing pad 200 , for example, is one or more metal sheets or metal coatings, which can be disposed on the main body of the notebook computer 10 for sensing (user) human body current. In Figure 1, two sensing pads 200 are disposed at the edge of the same surface as the keyboard of the notebook computer 10, but the invention is not limited to this. In addition, the sensing pad 200 can extend from the edge of the surface to the back to increase the sensing area.

The input terminal of the multiplex sensor 205 is coupled to the sensing pad 200, and according to the selection signal SS output by the microcontroller 206, the human body electrical signal sensed by the sensing pad 200 is output from one of the output terminals A to D. The human body electrical signal here is, for example, human body current or voltage corresponding to the user's human body impedance.

The first detection device 201 is configured to amplify the first current to output the first amplified current when receiving the first current; the second detection device 202 is configured to amplify the second current to output the first amplified current when receiving the second current. Outputs the second amplified current. The third detection device 203 is configured to amplify the third current to output the third amplified current when receiving the third current; the fourth detection device 204 is configured to amplify the fourth current to output the third amplified current when receiving the fourth current. Four amplify the current. In some embodiments, the first to fourth detection devices 201 to 204 are respectively bipolar junction transistors (Bipolar Junction transistors). Transistor, BJT)T1~T4. For BJT transistors T1~T4, each has its own current gain β1~β4, and β1~β4 can have the same value or different values.

The base of BJT transistor T1 is coupled to the emitter of BJT transistor T2 through switch SW1, the base of BJT transistor T2 is coupled to the emitter of BJT transistor T3 through switch SW2, and the BJT The base of the transistor T3 is coupled to the emitter of the BJT transistor T4 through the switch SW3. Moreover, the collector of each of the BJT transistors T2 to T4 can be connected to the power supply device VR through the switches SW4, SW5, and SW6 respectively, or directly connected to the power supply device VR, and the BJT transistor T1 The collector of is also coupled to the power supply device VR; wherein, the aforementioned power supply device VR is also coupled to the emitter of the BJT transistor T1. In addition, the bases of each of the BJT transistors T1 - T4 are also coupled to the outputs A, B, C and D of the multiplexer 205 respectively.

The switches SW1 and SW4 are turned on or off according to the control signal Sc1 output by the microcontroller 206 . The switches SW2 and SW5 are turned on or off according to the control signal Sc2 output by the microcontroller 206 . The switches SW3 and SW6 are turned on or off according to the control signal Sc3 output by the microcontroller 206 . In this implementation, for example, when Sc1, Sc2, and Sc3 are at logic high levels, the switches SW1~SW6 are turned on; when Sc1, Sc2, and Sc3 are at logic low levels, the switches SW1~SW6 are turned off.

The self-correcting contact sensing device 20 may further include a current reading device 207 and an indicating device 208 . In this embodiment, the reading device 207 and the indicating device 208 are disposed between the collector of the BJT transistor T1 and the power supply device VR. read The fetching device 207 includes, for example, a resistor R as a current sensor and a comparator CP. The current flowing through the BJT transistor T1 is sensed by the resistor R and converted into a voltage, and then the comparator CP outputs the signal Vout to the microcontroller 206 . The indicating device 208 is, for example, a light emitting diode LED.

The operation of the self-correcting contact sensing device 20 of the present invention will be described in detail below.

After the notebook computer 10 is turned on or started, the microcontroller 206 of the self-calibrating contact sensing device 20 will output the enable signal EN to the power supply device VR. After the power supply device VR is enabled, it provides a bias voltage to the BJT transistor T1. When the user uses the notebook computer 10 and touches the sensing pad 200 , the self-calibrating contact sensing device 20 will adjust the on/off combination of the switches SW1 ~ SW6 so as to detect whether the user still maintains It is in contact with the sensing pad 200 .

During the initial setting, the microcontroller 206 outputs logic low level control signals Sc1 to Sc3, causing the switches SW1 to SW6 to be closed. Furthermore, the microcontroller 206 outputs the selection signal SS, causing the multiplexer 205 to send the human body electrical signal (human body current) sensed by the sensing pad 200 from the output terminal A. The base of the BJT transistor T1 receives the human body current (as the first current) and amplifies the human body current into the first amplified current. The reading device 207 outputs the signal Vout to notify the microcontroller 206. When the microcontroller 206 determines that the value of the first amplified current is greater than a critical value, the microcontroller 206 maintains the on/off state of the switches SW1~SW6 and maintains The multiplexer 205 sends the human body electrical signal from the output terminal A, thereby completing the setting of detecting user contact.

If the microcontroller 206 determines that the value of the first amplified current (the current amplified by the human body electrical signal through the BJT transistor T1) is not greater than the critical value, the microcontroller 206 outputs a logic high level control signal Sc1 to switch The switches SW1 and SW4 are turned on and output logic low level control signals Sc2 and Sc3, causing the switches SW2, SW5, SW3 and SW6 to be closed. Furthermore, the microcontroller 206 outputs the selection signal SS, causing the multiplexer 205 to send the human body electrical signal sensed by the sensing pad 200 from the output terminal B. After the base of the BJT transistor T2 receives the human body electrical signal (as the second current), it amplifies the human body electrical signal into the second amplified current. The second amplified current flows to the base of the BJT transistor T1 through the switches SW4 and SW1. The BJT transistor T1 further amplifies the second amplified current to generate a first amplified current. When the microcontroller 206 determines that the value of the first amplified current (the current amplified by the second amplified current through the BJT transistor T1) is greater than a critical value, the microcontroller 206 will keep the switches SW1 and SW4 on, and SW2 and SW5, SW3 and SW6 are closed, and the multiplexer 205 is kept from sending human body electrical signals from the output terminal B; thus, the setting of detecting user contact is completed.

If the microcontroller 206 determines that the value of the first amplified current (the current amplified by the human body electrical signal through the BJT transistors T2 and T1) is not greater than the critical value, the microcontroller 206 outputs a logic high level control signal Sc1 , Sc2, turning on the switching switches SW1 and SW4, and SW2 and SW5, and outputting a logic low level control signal Sc3, turning the switching switches SW3 and SW6 off. Furthermore, the microcontroller 206 outputs the selection signal SS, causing the multiplexer 205 to send the human body electrical signal sensed by the sensing pad 200 from the output terminal C. The base of BJT transistor T3 receives the human body electrical signal (as the After three currents), the human body's electrical signal will be amplified as the third amplified current. This third amplified current flows to the base of the BJT transistor T2 through the switches SW5 and SW2. The BJT transistor T2 further amplifies the third amplified current to generate a second amplified current. The second amplified current (which is the third amplified current that is amplified by the BJT transistor T2) flows through the switches SW5 and SW2 to the base of the BJT transistor T1. The BJT transistor T1 further amplifies the second amplified current to generate a first amplified current. At this time, when the microcontroller 206 determines that the value of the first amplified current (which is the third amplified current amplified by the BJT transistor T2 and then amplified by the BJT transistor T1) is greater than the critical value, the microcontroller 206 206 will keep the switches SW1 and SW4, and SW2 and SW5 on, while SW3 and SW6 are off, and keep the multiplexer 205 from sending human body electrical signals from the output terminal C; thus completing the detection of user contact. settings.

If the microcontroller 206 determines that the value of the first amplified current (the current amplified by the human body current through the BJT transistors T3, T2 and T1) is not greater than the critical value, the microcontroller 206 outputs a logic high level control signal. Sc1~Sc3, turn on the switches SW1~SW6. Furthermore, the microcontroller 206 outputs the selection signal SS, causing the multiplexer 205 to send the human body current sensed by the sensing pad 200 from the output terminal D. The subsequent actions are the same as mentioned above and will not be repeated. When the microcontroller 206 determines that the value of the first amplified current (the current amplified by the human body current through the BJT transistors T4 ~ T1 ) is greater than a critical value, the microcontroller 206 maintains the conduction state of the switches SW1 ~ SW6 and maintains The multiplexer 205 sends the human body electrical signal from the output terminal D, thus completing the setting.

As can be seen from the above, after the notebook computer device 10 of the embodiment of the present invention is turned on or started, the self-calibrating contact sensing device 20 will be set according to the user's contact to confirm the situation of different users. Since different users have different body impedances, when the user touches the sensing pad 200, the electrical signal response caused by the user's body impedance on the sensing pad 200, such as (human body) current, voltage, etc., will also be different. Sometimes the human body electrical signal (current/voltage) is too small, causing the self-correcting touch sensing device 20 to be unable to sense it with only a single BJT transistor T1. Therefore, in this embodiment, in the initial setting stage of human body contact as mentioned above, if the human body current cannot be detected by the BJT transistor T1 alone (that is, the first amplified current is not greater than the critical value), the self- The calibrated contact sensing device 20 will set the on/off state of the switching devices SW1 to SW6, so that the BJT transistor T2 and the BJT transistor T1 jointly amplify and detect human body electrical signals. In the same way, if the BJT transistors T2 and T1 are still unable to detect human body electrical signals, the self-correcting contact sensing device 20 will set the on/off switching devices SW1 ~ SW6 so that the BJT transistors T3 ~ T1 Amplify and detect human body electrical signals. If the BJT transistors T3 ~ T1 are still unable to detect the human body electrical signal, the self-correcting contact sensing device 20 will set the switching devices SW1 ~ SW6 to be on/off, so that the BJT transistors T4 ~ T1 will conduct human body electrical signals together. Amplification and detection of signals to complete the setting of detecting human contact.

Assume that the computer device 10 of this embodiment has three users U1 to U3. When the user U1 turns on the notebook computer device 10, the user touches the sensing pad 200. After the self-correcting contact sensing device 20 is operated, the The microcontroller 206 performs self-correction so that the switches SW1 ~ SW6 are all turned on, and uses the multiplexer 205 to select from the output Terminal D sends the human body current to the BJT transistor T4, which completes the setting of detecting the user's human body contact. Similarly, when the user U2 turns on the notebook computer device 10, the user touches the sensing pad 200. After the contact sensing device 20 is operated, the microcontroller 206 performs self-calibration, for example, the switches SW1~SW2 are turned on. are all turned on, and the multiplexer 205 is used to send the human body current from the output terminal B to the BJT transistor T2. In addition, when the user U3 turns on the notebook computer device 10, the user touches the sensing pad 200. After the contact sensing device 20 is operated, the microcontroller 206 performs self-calibration. For example, the switches SW1~SW6 are still remains off, and uses multiplexer 205 to still send body current from output terminal A to BJT transistor T1. It can be seen from the above that for different users U1 ~ U3, the self-calibrating contact sensing device 20 can change the on/off state of the switches SW1 ~ SW6 and select to output the human body current to different BJT transistors to achieve detection. Self-correction for measuring human body contact of different users.

After the user contact setting is completed, if the user U1 (, U2, or U3) leaves the notebook computer 10 during normal use of the notebook computer 10, since there is no user contact with the sensing pad 200, the self-corrected contact The microcontroller 206 of the sensing device 20 will know that the first amplified current will be lower than the critical value. At this time, the microcontroller 206 will further notify the processor 101, and the processor 101 will drive the notebook computer device 10 to enter the power saving mode. . In addition, when the user returns to work in front of the notebook computer 10, as long as the user's hand touches the sensing pad 200, the self-calibrating contact sensing device 20 provided in the notebook computer 10 can detect the user's use. The current caused by the user's human body impedance further notifies the processor 101 to quickly wake up the notebook computer 10 .

In some embodiments, the critical value may be The current value or the corresponding voltage value when the LED (indicating device 208) lights up. The illuminated light-emitting diode LED notifies the user that the setting of detecting human contact is completed.

2)，亦即電晶體的數目為等於或大於二，其目的為欲含括一般正常人體阻抗的電性特徵都可以被偵測得出，俾能符合相關電子裝置之前述應用。另外，多工選擇器的輸出與BJT電晶體的個數一致即可。 In this embodiment, four BJT transistors are used in conjunction with a 1-input-4-output multiplex selector, but the invention is not limited thereto. For example, the BJT transistors used in the present invention can be T1, T2,...Tn(n

2), that is, the number of transistors is equal to or greater than two, and its purpose is to include the electrical characteristics of normal human body impedance that can be detected, so that it can meet the aforementioned applications of related electronic devices. In addition, the output of the multiplexer selector can be consistent with the number of BJT transistors.

The use of words such as "first", "second", and "third" in the scope of the patent application are used to modify the elements in the scope of the patent application, and are not used to indicate the order of priority, precedence relationship, or relationship between them. The precedence of one element over another, or the chronological order in which method steps are performed, is only used to distinguish elements with the same name.

Although the present invention is disclosed above in terms of preferred embodiments, they are not intended to limit the scope of the present invention. Anyone with ordinary skill in the art may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended patent application scope.

20: Self-calibrating contact sensing device

200: Sensing pad

201-204: First to fourth detection devices

205:Multiple selector

206: Microcontroller (μC)

207:Reading device

208:Indicating device

T1-T4:BJT transistor

SS: select signal

SW1-SW6: switch

Sc1-Sc3: control signal

R: resistor

CP: Comparator

EN: enable signal

A-D: Output of multiplexer

Vout: the output of the reading device

VR: power supply device

Claims (11)

A self-correcting contact sensing device includes: a sensing pad for sensing human body electrical signals; a first detection device that amplifies the first electrical signal and outputs a first amplified electrical signal when receiving a first electrical signal. signal; a second detection device, when receiving a second electrical signal, amplifies the second electrical signal and outputs a second amplified electrical signal; a multiplex selector, coupled to the sensing pad, selects the above-mentioned The human body electrical signal is output to the first detection device as the first electrical signal, or the human body electrical signal is output to the second detection device as the second electrical signal; a first switch is coupled to the first The detection device and the above-mentioned second detection device are turned on or off according to the control signal; and a microcontroller is coupled to the above-mentioned first detection device and the above-mentioned multiplex selector; wherein, the above-mentioned microcontroller, when the above-mentioned third When an amplified electrical signal is greater than a critical value, it is determined that the sensing pad is in contact with the human body; if the first amplified electrical signal is not greater than the critical value, the microcontroller outputs the selection signal to control the multiplexer to select the human body electrical signal. The signal is output to the second detection device as the second electrical signal, and the control signal is output to control the conduction of the first switch, and the second amplified electrical signal is input to the first detection device as the first electrical signal. . For example, the contact sensing device of claim 1 further includes: The third detection device, when receiving a third electrical signal, amplifies the third electrical signal and outputs the third amplified electrical signal; and a second switch is coupled to the second detection device and the third detection device. , and is turned on or off according to the above-mentioned control signal; wherein, the above-mentioned multiplex selector, according to the above-mentioned selection signal, can select the above-mentioned human body electrical signal as the above-mentioned third electrical signal and output it to the above-mentioned third detection device; when the above-mentioned multiplexer selector The manual selector selects the human body electrical signal to be output to the second detection device as the second electrical signal, and when the value of the first amplified electrical signal is not greater than the critical value, the microcontroller further uses the selection signal, The multiplex selector is changed to output the human body electrical signal to the third detection device as the third electrical signal; and the controller further turns on the second switch through the control signal, so that the above The third amplified electrical signal of the third detection device is supplied to the second detection device as the second electrical signal, and the second amplified electrical signal of the second detection device is supplied to the first electrical signal as the first electrical signal. a detection device. The contact sensing device of claim 2 further includes: a reading device coupled to the first detection device and the microcontroller for sensing the value of the first amplified electrical signal. The contact sensing device of claim 2, wherein the first detection device, the second detection device, and the third detection device are a first BJT transistor (bicarrier junction transistor), a second BJT transistor, and the third BJT transistor. The contact sensing device of claim 4, wherein the emitter of the third BJT transistor is coupled to the base of the second BJT transistor through the second switch, and the emitter of the second BJT transistor is coupled to the base of the second BJT transistor through the second switch. A switch is coupled to the base of the first BJT transistor; each output of the multiplexer is coupled to the base of the first BJT transistor to the third BJT transistor respectively. The contact sensing device of claim 5 further includes: a power supply device coupling the first BJT transistor to the collector of the third BJT transistor and the emitter of the first BJT transistor. The contact sensing device of claim 3 further includes: an indication device coupled to the first detection device, and when the value of the first amplified electrical signal is greater than the threshold value, it is used to indicate that the sensing pad is in contact with a human body. The contact sensing device of claim 7, wherein the indicating device is a light-emitting diode device, which is lit when the value of the first amplified electrical signal is greater than the threshold value. The contact sensing device of claim 6 further includes: a third switch coupled to the collector of the second BJT transistor and the power supply device, and having the same on/off state as the first switch; And a fourth switch is coupled to the collector of the third BJT transistor and the power supply device, and has the same on/off state as the second switch. An electronic device including: The self-correcting contact sensing device as described in any one of claims 1 to 9; and a processor; wherein the contact sensing device determines the on/off state of the switch and the multiplexer. After the output, when the microcontroller determines that the sensing pad is not in contact with the human body, it further notifies the processor, and the processor drives the electronic device to enter the power saving mode. The electronic device of claim 10, wherein the electronic device is a notebook computer; and the sensing pad is one or more metal sheets or metal coatings disposed on the same plane as the keyboard of the notebook computer. .

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