Abstract:
The present invention discloses an event detection method for waking up a portable electronic device and an action sensor using same. The event detection method includes the steps of: under a normal operation mode, sensing action events by the action sensor with a first data sensing frequency, wherein the action sensor operates by a normal current to detect the action events; entering into a sleep mode; under the sleep mode, detecting a wake-up event by the action sensor with a second data sensing frequency, wherein the action sensor operates by a weak current to detect the wake-up event, wherein the weak current is smaller than the normal current, and the second data sensing frequency is not higher than the first data sensing frequency; and returning to the normal operation mode when the wake-up event is detected.

Description:
BACKGROUND OF THE INVENTION 
     Field of Invention 
     The present invention relates to an event detection method for waking up a portable electronic device and an action sensor using same; particularly, it relates to such event detection method and action sensor capable of accurately detecting a wake-up event when the portable electronic device is in a sleep mode. 
     Description of Related Art 
     Please refer to  FIG. 1A  and  FIG. 1B , which show how the prior art switches a portable electronic device from a sleep mode to a normal operation mode and its drawback. When a portable electronic device is power ON but has not been in use for a certain period of time, typically, its power management system will shut down the operations of at least some of its components to reduce power consumption, which is the “sleep mode”. In the “normal operation mode” the portable electronic device operates normally, i.e., all the components of the portable electronic device are in operation or ready for operation. In the “sleep mode”, one or more of the components of the portable electronic device are not fully functioning such that the power consumption is reduced. 
     Conventionally, in a portable electronic device having an action sensor such as a capacitive touch sensor, an acceleration sensor, a gyro-sensor or the like, the action sensor is shut down in the sleep mode to reduce power consumption. Referring to  FIG. 1A , in the normal operation mode, the action sensor senses action events with a data sensing frequency CLK 1  (e.g., 100 Hz). During this normal operation mode, the action sensor is supplied with a current In (referring to as “normal current” hereinafter) which is sufficient for the action sensor to fully function, so as to sense action events with the best accuracy and resolution. When the portable electronic device enters into the sleep mode, the action sensor is shut down. However, a user may cause a certain wake-up event to happen, such as tapping a screen of the portable electronic device, in order to wake up the portable electronic device to resume it from the sleep mode to the normal operation mode. Therefore, although the action sensor is shut down, it should not be completely disabled, and typically in the prior art, the action sensor still senses action events but with a greatly reduced data sensing frequency. For example, referring to  FIG. 1A , in the sleep mode, the action sensor detects whether there is a wake-up event with a much lower data sensing frequency CLK 0  (typically about 1/100 of the data sensing frequency CLK 1 , e.g., 1 Hz). When a wake-up event is detected under this much lower data sensing frequency CLK 0 , the portable electronic device is resumed from the sleep mode to the normal operation mode. 
     Referring to  FIG. 1B , the drawback of the prior art is that there is high possibility that the action sensor can not capture a wake-up event during the sleep mode. Typically, a user&#39;s tapping action is in a frequency range of about 10 Hz. With the low data sensing frequency CLK 0 , it is very likely that the action sensor will miss the tapping action, and as a result, the portable electronic device will not resume from the sleep mode to the normal operation mode. 
     In view of the above, to overcome the drawbacks in the prior art, the present invention proposes an event detection method for waking up a portable electronic device and an action sensor using the same, wherein such event detection method and action sensor are capable of accurately detecting a wake-up event when the portable electronic device is in a sleep mode. 
     SUMMARY OF THE INVENTION 
     From one perspective, the present invention provides an event detection method for waking up a portable electronic device having an action sensor, comprising the steps of: under a normal operation mode, sensing action events by the action sensor with a first data sensing frequency, wherein the action sensor operates by a normal current to detect the action events; entering into a sleep mode wherein at least one component of the portable electronic device is not fully functioning to reduce power consumption; under the sleep mode, detecting a wake-up event by the action sensor with a second data sensing frequency, wherein the action sensor operates by a weak current to detect the wake-up event, wherein the weak current is smaller than the normal current, and the second data sensing frequency is not higher than the first data sensing frequency; and returning to the normal operation mode when the wake-up event is detected. 
     From another perspective, the present invention provides an action sensor for use in a portable electronic device, comprising: a clock circuit for providing a first data sensing frequency under a normal operation mode and a second data sensing frequency under a sleep mode, wherein the second data sensing frequency is not higher than the first data sensing frequency, and wherein in the sleep mode, at least one component of the portable electronic device is not fully functioning to reduce power consumption; a current generation circuit for supplying a normal current under the normal operation mode and supplying a weak current under the sleep mode, wherein the weak current is smaller than the normal current; and an event detection circuit coupled to the clock circuit and the current generation circuit, for sensing action events with the first data sensing frequency under the normal operation mode or detecting a wake-up event with the second data sensing frequency under the sleep mode, wherein the event detection circuit operates by the normal current to detect the action events under the normal operation mode, and wherein the event detection circuit operates by the weak current to detect the wake-up event under the sleep mode; wherein the action sensor generates an output signal for resuming the portable electronic device to the normal operation mode when the wake-up event is detected by the event detection circuit. 
     In one embodiment, the action sensor further comprises: a sleep mode controller coupled to the clock circuit and the current generation circuit, for providing a mode switching signal to the clock circuit and to the current generation circuit, to switch a data sensing frequency of the clock circuit between the first and second data sensing frequencies and to switch a current provided by the current generation circuit between the normal current and the weak current. 
     In one embodiment, the weak current is greater than zero and smaller than or equal to 50% of the normal current. 
     In the above-mentioned embodiment, the weak current is preferably 20%˜40% of the normal current. 
     In one embodiment, the step of entering into a sleep mode is triggered manually or automatically. 
     In one embodiment, the action sensor is a capacitive sensor sensing the action events and detecting the wake-up event according to a change of capacitance. 
     In one embodiment, a sensitivity of the capacitive sensor is related to an operation current of the capacitive sensor, and when the capacitive sensor operates by the weak current, the sensitivity of the capacitive sensor is lower than the sensitivity when the capacitive sensor operates by the normal current. 
     In one embodiment, the first data sensing frequency ranges between 80˜120 Hz and the second data sensing frequency ranges between 20˜60 Hz. 
     The objectives, technical details, features, and effects of the present invention will be better understood with regard to the detailed description of the embodiments below, with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1B  show how prior art switches a portable electronic device from a sleep mode to a normal operation mode and its drawback. 
         FIG. 2  shows how the present invention switches a portable electronic device from a sleep mode to a normal operation mode. 
         FIG. 3  shows a flow chart of an event detection method according to an embodiment of the present invention. 
         FIG. 4  shows a block diagram of an action sensor according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The above and other technical details, features and effects of the present invention will be will be better understood with regard to the detailed description of the embodiments below, with reference to the drawings. The drawings as referred to throughout the description of the present invention are for illustration only, to show the interrelations between the components and devices, but not drawn according to actual scale. 
     Please refer to  FIGS. 2-4 .  FIG. 2  shows how the present invention switches a portable electronic device from a sleep mode to a normal operation mode.  FIG. 3  shows a flow chart of an event detection method according to an embodiment of the present invention.  FIG. 4  shows a block diagram of an action sensor according to an embodiment of the present invention. 
     As shown in  FIG. 4 , a portable electronic device  100  includes an action sensor  10 . The portable electronic device  100  includes other components such as a screen, a graphic controller, etc., which are omitted because they are not relevant to the present invention. The action sensor  10  senses action events in the normal operation mode and detects a wake-up event in the sleep mode. In one embodiment, the action sensor  10  is a capacitive sensor sensing the action events and detecting the wake-up event according to a change of capacitance. The action sensor  10  is for example a capacitive touch sensor, an acceleration sensor, or a gyro-sensor. 
     The action sensor  10  of this embodiment comprises an event detection circuit  11 , a clock circuit  12  and a current generation circuit  13 . In one embodiment, the action sensor  10  further comprises a sleep mode controller  14 , coupled to the clock circuit  12  and the current generation circuit  13 . 
     Please refer to  FIG. 4  in conjugation with  FIG. 2 . In one embodiment, the event detection circuit  11  is coupled to the clock circuit  12  and the current generation circuit  13 . The clock circuit  12  provides a data sensing frequency CLK 1  in the normal operation mode and a data sensing frequency CLK 2  in the sleep mode, wherein the data sensing frequency CLK 2  is not higher than the data sensing frequency CLK 1  and preferably lower than the data sensing frequency CLK 1 . The current generation circuit  13  supplies a normal current In in the normal operation mode and a weak current Iw in the sleep mode, wherein the weak current Iw is lower than the normal current In. In one embodiment, whether the clock circuit  12  provides the data sensing frequency CLK 1  or the data sensing frequency CLK 2 , and whether the current generation circuit  13  supplies the normal current In or the weak current Iw are controlled by a mode switching signal MS generated by the sleep mode controller  14 . In another embodiment, the sleep mode controller  14  can be omitted and the frequency and current switching can be controlled by a circuit in the portable electronic device  100 , such as a micro-controller unit already existing in the portable electronic device  100 . 
     In one embodiment, the sleep mode controller  14  can be triggered manually and/or automatically to generate the mode switching signal MS, to switch the portable electronic device  100  from the normal operation mode to the sleep mode. For example, a user can input a command to switch the portable electronic device  100  to the sleep mode. For another example, when a predetermined period of time has passed and the portable electronic device  100  does not receive any command from the user, the sleep mode controller  14  can be triggered automatically to switch the portable electronic device  100  to the sleep mode. The same principle applies when the sleep mode controller  14  is omitted. 
     Please refer to  FIGS. 2-4 . In the normal operation mode, the event detection circuit  11  of the action sensor  10  senses action events by the data sensing frequency CLK 1 . In one embodiment, the data sensing frequency CLK 1  can range between, for example but not limited to, 80˜120 Hz. The actual value of data sensing frequency CLK 1  can be set depending on practical needs. During this normal operation mode, the event detection circuit  11  of this embodiment is supplied with a normal current In so as to sense the action events (as shown by the step S 11  in  FIG. 3 ). The normal current In is sufficient for the event detection circuit  11  to fully function, so as to sense action events with the best accuracy and resolution. The actual value of normal current In can be set depending on practical needs. 
     As shown by the steps S 12  and S 13  in  FIG. 3  and as explained in the above, manually or automatically, the portable electronic device  100  can be switched to the sleep mode. During the sleep mode, the event detection circuit  11  is supplied with the weak current Iw, and the event detection circuit  11  detects the occurrence of a wake-up event with the data sensing frequency CLK 2 . The data sensing frequency CLK 2  is not higher than the data sensing frequency CLK 1 . In one embodiment, the data sensing frequency CLK 2  is the same as the data sensing frequency CLK 1  (i.e., the data sensing frequency CLK 1  can be directly used as the data sensing frequency CLK 2 ). In another embodiment, to reduce power consumption, the data sensing frequency CLK 2  is preferably lower than the data sensing frequency CLK 1 , more preferably lower than or equal to 50% of but higher than a frequency of a human&#39;s action which the action sensor  10  is designed to sense. In one embodiment, the data sensing frequency CLK 2  can range between, for example but not limited to, 20˜60 Hz. 
     Besides, note that, in this embodiment of the present invention, the weak current Iw under the sleep mode is smaller than the normal current In under the normal operation mode. In one embodiment, the weak current Iw is set to be greater than zero and smaller than or equal to 50% of the normal current In. In a more preferable embodiment, the weak current Iw can be set to be for example but not limited to 20%-40% of the normal current In, such as 25%. Because the event detection circuit  11  (and hence the action sensor  10 ) operates by the weak current Iw, in a case that a sensitivity of the event detection circuit  11  (and hence the action sensor  10 ) is related to an operation current thereof, when the event detection circuit  11  operates by the weak current Iw, the sensitivity of the event detection circuit  11  is lower than the sensitivity when the event detection circuit  11  operates by the normal current In. However, this is alright because in the sleep mode, the event detection circuit  11  is not required to sense action events by a high accuracy and sensitivity; the event detection circuit  11  is only required to capture a wake-up event (the step S 14 ). Action events may involve sophisticated behaviors such as dragging an icon on a screen or sliding toward a direction, etc. which need to be correctly interpreted; however, to switch the portable electronic device  100  from the sleep mode to the normal operation mode, it is only required to detect an occurrence of a wake-up event, i.e., whether there is or is not a wake-up event, and it is not required to read the wake-up action in detail. 
     Please refer to  FIG. 2  in contrast with  FIG. 1B . Note that, unlike the prior art where the data sensing frequency CLK 0  under the sleep mode is set to be very slow (e.g., 1 Hz), the data sensing frequency CLK 2  of the present invention is greater than the data sensing frequency CLK 0  of the prior art. because this data sensing frequency CLK 2  is higher than a frequency of a human&#39;s action which the action sensor  10  is designed to sense, it is much less likely that the action sensor  10  misses a wake-up event; in contrast, the prior art very likely misses the wake-up event. 
     In addition, although the present invention senses a wake-up event by a higher data sensing frequency than the prior art, because the action sensor  10  operates by the weak current Iw in the sleep mode (in comparison, the prior art operates by the normal current In in the sleep mode), the present invention still greatly reduces power consumption in the sleep mode. More importantly, in comparison with the prior art, the present invention can correctly capture a wake-up event without miss. 
     The present invention has been described in considerable detail with reference to certain preferred embodiments thereof. It should be understood that the description is for illustrative purpose, not for limiting the scope of the present invention. An embodiment or a claim of the present invention does not need to achieve all the objectives or advantages of the present invention. The title and abstract are provided for assisting searches but not for limiting the scope of the present invention. Those skilled in this art can readily conceive variations and modifications within the spirit of the present invention. In view of the foregoing, the spirit of the present invention should cover all such and other modifications and variations, which should be interpreted to fall within the scope of the following claims and their equivalents.