Abstract:
A dual power switch system and the related control method thereof. The dual power switch system includes: a power supply module for supplying power to the dual power switch system; a first power switch circuit, electrically connected to the power supply module, for generating a first control voltage to trigger the power supply module to supply the power; and a second power switch circuit, electrically connected to the power supply module, for generating a second control voltage through magnetic induction to trigger the power supply module to supply the power.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a power switch system and a related control method, and more specifically, to a dual power switch system and a related control method. 
   2. Description of the Prior Art 
   In recent years, the major reasons for the popularity of digital cameras have been the rapidly-declining prices and increasingly simplified operation methods. The market is highly competitive, so manufacturers need to continuously develop digital cameras with special functions or special exterior designs to attract consumers to purchase their products. A digital camera with a dual power switch can be given as an example. 
   In addition to an original power switch, the conventional digital camera with the dual power switch utilizes a lens sliding cap mechanism to control the other switch circuit. For example, an elastic wedge is installed on a housing of the digital camera. When moving the lens sliding cap to uncover the lens, the elastic wedge is pressed so that the power supply module of the digital camera is activated to allow the digital camera to start operating. When the lens sliding cap covers the lens again, the elastic wedge will return to its original state and the power supply module is turned off in order to turn off the digital camera. The goal of triggering the power switch can be successfully achieved by using the above mechanism; however, this mechanism affects the exterior design of the digital camera, increases the complexity of the housing mold and increases the production cost. 
   SUMMARY OF THE INVENTION 
   One of the objectives of the claimed invention is therefore to provide a dual power switch system and a related control method, in order to solve the above-mentioned problem. 
   According to the claimed invention, a dual power switch system is disclosed. The dual power switch system comprises: a power supply module for supplying power to the dual power switch system; a first power switch circuit, electrically connected to the power supply module, for generating a first control voltage to trigger the power supply module to supply the power; and a second power switch circuit, electrically connected to the power supply module, for generating a second control voltage through magnetic induction to trigger the power supply module to supply the power. 
   In addition, the claimed invention provides a control method for a dual power switch system. The control method comprises: (a) supplying power to the dual power switch system; (b) generating a first control voltage to trigger step (a); and (c) generating a second control voltage to trigger step (a) through magnetic induction. 
   According to the claimed invention, an image capture device is disclosed. The image capture device comprises: a power supply module for supplying power to the image capture device; and a power switch circuit, electrically connected to the power supply module, for generating a control voltage through magnetic induction to trigger the power supply module to supply the power. 
   The second power switch circuit according to the claimed invention generates a control voltage to control the power supply module through magnetic induction, instead of the related art method in which a conventional digital camera utilizes a sliding mechanism to control a power supply module. In addition, the first power switch circuit and the second power switch circuit according to the claimed invention can independently operate without affecting each other. 
   These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an external view diagram of an image capture device with a dual power switch system according to the present invention. 
       FIG. 2  is a diagram showing an open position of the sliding lens cap of the image capture device shown in  FIG. 1 . 
       FIG. 3  is a schematic diagram of an embodiment of a dual power switch system according to the present invention. 
       FIG. 4  is a timing diagram of the control voltages V 1 , V 2 , V 3 , V 4 , V 5 , and V 6 . 
   

   DETAILED DESCRIPTION 
   The dual power switch system according to the present invention is simple, so it can be applied to common portable electronic devices, such as digital cameras, mobile phones, or personal digital assistants (PDA) etc. Please refer to  FIG. 1 .  FIG. 1  is an external view diagram of an image capture device  10  with a dual power switch system according to the present invention. The image capture device  10  could be a digital camera, comprising: a housing  12 , a sliding lens cap  14 , a magnetic component  16 , a magnetic induction device  18  and a lens  22 . The magnetic component  16  is fixed on the inside of the sliding lens cap  14 . Hence, when the sliding lens cap  14  moves, the position of the magnetic component  16  changes accordingly. The description of the operation of the magnetic induction device  18  is included in the following paragraph. The magnetic induction device  18  can be selectively installed on the inside or on the outside of the housing  12 . When the sliding lens cap  14  moves towards the left, the magnetic induction device  18  can induct a change of the surrounding magnetic flux and then generate a control voltage. Please notice that the sliding lens cap  14  shown in  FIG. 1  is in a “closed” status, which means the lens  22  is covered by the sliding lens cap  14 , while the magnetic component  16  is on the right side of the magnetic induction device  18 . 
   Please refer to  FIG. 2 .  FIG. 2  is a diagram showing an open position of the sliding lens cap  14  of the image capture device  10  shown in  FIG. 1 . As shown in  FIG. 2 , in order to uncover the lens  22 , it is necessary to slide the sliding lens cap  14  shown in  FIG. 1  towards the left. Therefore, the magnetic component  16  shown in  FIG. 2  is on the left side of the magnetic induction device  18 . When the sliding lens cap  14  is sliding, the magnetic induction device  18  can detect a magnetic flux change and generate a pulse control voltage according to the amount of magnetic flux in order to control a power switch of the image capture device  10 . The detailed description of the related operation is included in the following paragraph. 
   Please refer to  FIG. 3 .  FIG. 3  is a schematic diagram of an embodiment of a dual power switch system  100  according to the present invention. The dual power switch system  100  comprises a power supply module  120 , a button power switch circuit  140 , a magnetic induction power switch circuit  160 , a control circuit  180  and a logic OR circuit  190 . In the present embodiment, the button power switch circuit  140  comprises a button switch S 1 , a transistor Q 1  and a plurality of resistors R 1 , R 2 , R 3 . When a user presses the button switch S 1 , the button switch S 1  temporarily short circuits and generates a control voltage V 1  at a high logical level (3.3V shown in  FIG. 3 ) on a terminal n 1  and inputs the control voltage V 1  into the logic OR circuit  190 . At the same time, the transistor Q 1  is conductive because the control voltage V 1  is at a high logical level, and also generates a control voltage V 2  at a low logical level on a terminal n 2  (i.e. 0V) to inform the control circuit  180 . It should be noted that when the button switch S 1  does not short circuit, the control voltage V 1  remains at a low logical level, and the control voltage V 2  remains at a high logical level. The short circuited status of the button switch S 1  is only true for a certain period of time, so a pulse signal is formed in the control voltages V 1  when pressing the button switch S 1 . 
   In the present embodiment, the magnetic induction power switch circuit  160  comprises a Hall sensor U 1  (the magnetic induction device  18  shown in  FIG. 1 ), a transistor Q 2 , a plurality of resistors R 4 , R 5 , R 6  and a magnetic sliding cap (not shown). The magnetic sliding cap is the magnetic component  16  and the sliding lens cap  14  shown in  FIG. 1 . Therefore, no matter whether the magnetic sliding cap is slid open or slid closed, this action causes the Hall sensor U 1  to detect a magnetic flux change. When the magnetic flux change is greater than a threshold value, the Hall sensor U 1  outputs a control signal V 3  at a low logical level on a terminal n 3 ; otherwise the control signal V 3  remains at a high logical level. When the sliding lens cap  14  is slid open or slid closed, the amount of the magnetic flux detected by the Hall sensor U 1  increases then decreases in a short time. Hence, the control signal V 3  will be similar to an upside-down pulse signal. The transistor Q 2  then inverses the control signal V 3  to generate a control signal V 4  and outputs the control signal V 4  on a terminal n 4  to the logic OR circuit  190  and the control circuit  180 . Hence, the control signal V 4  presents as a pulse signal. 
   The logic OR circuit  190  comprises a plurality of diodes, D 1 , D 2 , D 3 , utilized for performing logic or operations on the inputted control voltages V 1 , V 4 , V 5  so that a control voltage V 6  can be generated on a terminal n 5  and be sent to the power supply module  120 , wherein the control voltage V 5  is provided by the control circuit  180 . The description of generating the control voltage V 5  is included in the following paragraph. When the control voltage V 6  corresponds to the high logical level, this situation will drive the power supply module  120  to supply power to the control circuit  180 ; meanwhile the control circuit  180  can perform the related operations, such as firmware execution. On the other hand, when the control voltage V 6  corresponds to the low logical level, the power supply module  120  does not supply power to the control circuit  180  and the control circuit  180  is in a power-off status. Therefore, as long as any one of the control voltages V 1 , V 4 , V 5  corresponds to the high logical level, the power supply module  120  can be driven to supply power. When all of the control voltages V 1 , V 4 , V 5  correspond to the low logical level, the power supply module  120  is driven to stop supplying power. Because both of the control voltages V 1  and V 4  only can remain at the high logical level temporarily, however, it is necessary for the control circuit  180  to generate a stable control voltage V 5  further according to the control voltages V 2  and V 4  to constantly control the power supply module  120 . 
   Please refer to  FIG. 3  and  FIG. 4 .  FIG. 4  is a timing diagram of the control voltages V 1 , V 2 , V 3 , V 4 , V 5 , V 6 . In the present embodiment, the control circuit  180  is a microprocessor. After the power supply module  120  starts supplying power to the control circuit  180 , the control circuit  180  can operate in a normal condition. When the dual power switch system  100  is in an power-off status, if the user presses the button switch S 1  in a time interval t 1 , the button power switch circuit  140  pulls the control voltage V 1  high to generate a pulse signal and send the pulse signal to the power supply module  120 , and pulls the control voltage V 2  low at the same time. In the present, the control circuit  180  has not finished initialization yet; therefore the control circuit  180  cannot detect the control voltage V 2 . Also, the power supply module  120  temporarily supplies power to the control circuit  180  because of the pulled-high control voltage V 1 , allowing the control circuit  180  to start the initialization. After the completion of the initialization of the control circuit  180 , the control circuit  180  transmits a control voltage V 5  and keeps the control voltage V 5  at a high logical level to drive the power supply module  120  to constantly supply power. Therefore, the control circuit  180  can successfully finish booting. It should be noted that when the time interval t 1  is ended, the control voltage V 1  returns to the low logical level, and the control voltage V 2  also returns to the high logical level. Next, if a user presses the button switch S 1  again in the time interval t 2 , the button power switch circuit  140  will pull the control voltage V 1  high and pull the control voltage V 2  low again. When the control circuit  180  detects that the control voltage V 2  is pulled low, it will further pull the control voltage V 5  low. Therefore, after the time interval t 2  is ended, the control voltages V 1 , V 4 , V 5  all correspond to the low logical level to allow the power supply module  120  to stop supplying power; meanwhile, the control circuit  180  enters a power-off status. 
   In the same manner, when the dual power switch system  100  is in a power-off status, if the user slides open the lens cap to uncover the lens in the time interval t 3 , the magnetic induction power switch circuit  160  pulls the control voltage V 3  low and pulls the control voltage V 4  high at the same time to generate a pulse signal. Therefore, the control voltage V 6  that controls the power supply module  120  increases accordingly to control the power supply module  120  to temporarily supply power to the control circuit  180 . When the control circuit  180  completes the initialization, it sends a control voltage V 5  and keeps the control voltage V 5  at the high logical level to drive the power supply module  120  to constantly supply power. In this way, the control circuit  180  can successfully finish booting. Afterwards, if a user slides close the lens cap to cover the lens in a time interval t 4 , the magnetic induction power switch circuit  160  will pull the control voltage V 3  low and pull the control voltage V 4  high. Therefore, when the control circuit  180  detects that the control voltage V 4  is pulled high, it will pull the outputted control voltage V 5  low. When the time interval t 4  is ended, the control voltages V 1 , V 4 , V 5  all correspond to the low logical level and the power supply module  120  stops supplying power; meanwhile, the control circuit  180  enters a power-off status. 
   Please refer to  FIG. 3 . In the present embodiment, the control circuit  180  is a microprocessor, so it can be utilized for recording the open/closed status of the sliding lens cap  14  shown in  FIG. 1  to selectively omit the control voltage V 4  outputted by the magnetic induction power switch circuit  160 . For example, after the user presses the button switch S 1 , the digital camera will boot. If the control circuit  180  checks the system record and discovers that presently the lens cap is in a closed status, which means the lens is covered by the lens cap, an operation message “Please Uncover the lens” will be displayed on the screen to remind the user. Also, when uncovering the lens, though the control voltage V 4  corresponds to a high logical level, the control circuit  180  can recognize that the present change of the control voltage V 4  is not because the user needs to turn off the digital camera, and so the control circuit  180  will not change the logical state of the control voltage V 5 . 
   In contrast with the related art, the present invention utilizes a Hall sensor to generate a control voltage through magnetic induction to control the power supply module, instead of the related art method in which a conventional digital camera utilizes a sliding cap mechanism to control a power supply module. In this way, manufacturers are provided with more flexibility when designing the appearance of the product; moreover, the production cost can be reduced. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.