Abstract:
An arrangement and method for eliminating power failures, especially due to glitches, in a device is provided. The arrangement may include electrical components configured to be supplied with power, a power source for supplying the components, a capacitive element configured to provide a flash element with operational power. The arrangement may include a device for sensing power supplied from the power source, and means for redirecting power from the capacitive element to the electrical components when a power from the power source reduces to a predetermined level.

Description:
TECHNICAL FIELD 
       [0001]    The present invention generally relates to providing a charging capacitor and using the charging capacitor as a backup power source. 
       BACKGROUND OF THE INVENTION 
       [0002]    Communication devices, such as cellular telephones, are becoming increasingly versatile. For example, cellular telephones today often include applications that allow users to do more than just make and receive telephone calls, such as send/receive text messages, play music, play video games, take pictures, etc. Consequently, cellular telephones have become an increasingly common part of every day life for a large number of cellular telephone users. 
         [0003]    The functionality of taking pictures and consumer demands imply that more sufficient camera units are incorporated in the mobile phone. It is not unusual for cameras to be of high quality with superior resolution also allowing simple or high quality flash function using an intensive light emitting portion. The flash device is usually an ordinary or modified camera flash using a flash capacitor. 
         [0004]    Naturally, in all electrical devices, supplying power to the electrical components is an essential function. For mobile devices, in particular, the device is exposed to motion and vibrations which may affect performance of at least some functions of the device. Typically, the battery connects to the electronic components using non-fixed connectors, which may glitch and result in malfunction of the device. 
         [0005]    It is believed that on/off problems, especially due to glitches, are one of the major sources of user dissatisfaction with a device, which results in high rate return for a particular product. 
         [0006]      FIG. 1  illustrates a device  100 , such as a mobile phone, including a housing  101 , a power source such as a battery  110 , a camera portion  120 , controlling electronics  130 , a voltage transforming circuit  140 , a flash  150 , and a flash capacitor  160 . 
         [0007]    The device may include other electrical components/circuitry, e.g. transceiver and interface circuits in case of a mobile phone, well known to a skilled person, which are not described herein. 
         [0008]    A capacitor charging device for a flash, for example, disposed in a digital camera is used to charge the flash capacitor of the digital camera so as to provide electricity for producing the flash. As shown in the example of  FIG. 2 , the charging device may include a flash capacitor  260 , a voltage transforming circuit  240 , a current mode pulse width modulation (PWM) control circuit  231 , and a charging control circuit  232 . Voltage transforming circuit  240  may further include a transformer  241 , a diode D 1 , a resistor R 1 , and a transistor (MOSFET) Q 1 . 
         [0009]    When the charging device is initially activated, current mode PWM control circuit  231  may output a pulse current I to control the gate-to-source voltage VGS. Charging control circuit  232  may control the pulse width of current I with a time control capacitor (not shown). Since the capacitance of the time control capacitor is small, the soft start period (i.e., the period for reaching the maximum pulse width of current I) of current mode PWM control circuit  231  is very short. Hence, current mode PWM control circuit  231  can output pulse current I with maximum pulse width in a relatively short time. 
         [0010]    When pulse current I is “on” (i.e., a state with an output current), gate-to-source voltage VGS of MOSFET Q 10  may be positive and result in an increase of current ID passing through MOSFET Q 10 . While current ID increases, transformer  231  may generate an induced current I 0  to charge flash capacitor  260 . When pulse current I is “off” (i.e., a state with no output current), gate-to-source voltage VGS of MOSFET Q 1  may be zero and result in the decrease of current I 0 . While current I 0  decreases, due to the tremendous reverse resistance of diode D 10 , induced current I 0  may also reduce to zero. Thereby, flash capacitor  260  can be charged by induced current I 0  in the on-off cycle of pulse current I. 
       SUMMARY OF THE INVENTION 
       [0011]    Embodiments of the present invention provide a solution for power backup, which eliminates the problems with on/off due to power failure, e.g., because of power source connection glitches. 
         [0012]    Thus, the present invention according to a first aspect of the invention relates to a method in a device including electrical components configured to be supplied with power from a power source, the device including a capacitive element configured to provide a flash with operational power, the method including the steps of: sensing power from the power source, redirecting power from the capacitive element to the electrical components if a power supply failure is detected, and adjusting power level from the capacitive element to a level consumable by the electrical components. The capacitive element may include a flash capacitor. 
         [0013]    The invention also relates to an arrangement in a device including: electrical components configured to be supplied with power, a power source for supplying the components, a capacitive element configured to provide a flash element with operational power. The arrangement includes: a device for sensing power supplied from the power source, and means for redirecting power from the capacitive element to the electrical components when power from the power source reduces to a predetermined level. The arrangement may further include a power transformer for adjusting power level from the capacitive element to a level consumable by the electrical components. The power supply may be a battery. The capacitive element may be a flash capacitor. The arrangement may further include a controller circuit and a switching arrangement. The controller circuit receives information about the power supply of the power source to the electrical components. The switching arrangement may be configured to supply power from the power source to components that need electricity. A power backup controller arrangement may be configured to control a power transforming circuit so that power stored in the capacitive element is transformed down to a level usable by the electrical circuits. 
         [0014]    According to another aspect of the invention a device may include an image recording arrangement and a flash light, a capacitor for powering the flash light and a power source which are provided. The device may further include an arrangement including: a device for sensing power supplied from the power source, and means for redirecting power from the capacitive element to the electrical components when a power from the power source reduces to a predetermined level. The device may further include a communication portion for communicating in a communication network. The device may further include a housing, a display, control buttons, and a keypad. The device may further include charging control circuit, a voltage mode circuit, a voltage transforming circuit, a power direction control arrangement, and a power directing switch arrangement. In an embodiment for charging the capacitor, when the voltage across the flash capacitor is low, the charging control circuit may be arranged to provide a low voltage to activate the voltage mode control circuit, which may be arranged to output a voltage, the voltage mode control circuit may be arranged to provide a constant current to charge a capacitor of the charging control circuit, whereby the voltage mode control circuit may be arranged to increase a pulse width of the pulse voltage according to a voltage across the capacitor, the pulse voltage may drive the voltage transforming circuit to provide an induced current to charge the flash capacitor. The power backup controlling arrangement may redirect the function of the power transforming circuit so that the power stored in the flash capacitor may be transformed down to a suitable level for other electrical circuits in the device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and, together with the description, explain the invention. In the drawings: 
           [0016]      FIG. 1  illustrates schematically a state of the art solution; 
           [0017]      FIG. 2  illustrates schematically an embodiment according to the present invention; 
           [0018]      FIG. 3  illustrates a device incorporating an arrangement according to the present invention; and 
           [0019]      FIG. 4  illustrates a device incorporating an arrangement according to the present invention in further detail. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0020]    A “device,” as the term is used herein, is to be broadly interpreted to include a radiotelephone; a personal communications system (PCS) terminal that may combine a cellular radiotelephone with data processing, a facsimile, and data communications capabilities; a personal digital assistant (PDA) that can include a radiotelephone, pager, Internet/intranet access, web browser, organizer, calendar, a camera (e.g., video and/or still image camera), a sound recorder (e.g., a microphone), a Doppler receiver, and/or global positioning system (GPS) receiver; a laptop; a GPS device; a camera (e.g., video and/or still image camera); a sound recorder (e.g., a microphone); and any other computation or communication device capable of presenting media, such as a personal computer, a home entertainment system, a television, etc. 
         [0021]    A “glitch,” as the term is used herein, is to be broadly interpreted to include power supply failure, reduction, interruption, surge and/or other undesirable fluctation. 
         [0022]    As shown in  FIG. 3 , an exemplary device  300  may include a housing  310 , a display  311 , control buttons  312 , a keypad  313 , a communication portion  314 , a battery  315 , and a camera  320 . Housing  310  may protect the components of device  300  from outside elements. Display  311  may render visual information to the user. For example, display  311  may present information regarding incoming or outgoing calls, media, games, phone books, the current time, etc. Control buttons  312  may permit the user to interact with a device to cause the device to perform one or more operations. Keypad  313  may include a standard telephone keypad. Camera  320  may enable a user to capture and store video and/or images (e.g., pictures). The function of the camera unit together with the power backup system according to the present invention will be described in more detail below. The communication portion may include components (not shown) such as a receiver, a transmitter, an antenna, etc., for establishing and performing communication with one or several communication networks. 
         [0023]    Camera portion  320  in conjunction with the power backup portion according to the present invention, as illustrated in  FIG. 4 , may include image capturing electronics  321 , a camera lens  322 , a flash  450 , a flash capacitor  460 , a charging control circuit  470 , a voltage mode circuit  480 , a voltage transforming circuit  490 , a power direction control arrangement  444 , and a power directing switch arrangement  445 . It should be noted that voltage mode circuit  480  may be omitted or substituted with another type of voltage controlling arrangement. 
         [0024]    The operation of the camera per se is assumed to be well known by a skilled person and not described herein in detail. 
         [0025]    For charging the capacitor, when voltage across flash capacitor  460  is low, charging control circuit  470  may provide a low voltage to activate voltage mode control circuit  480  and make it output (pulse) voltage V 1 . Then, voltage mode control circuit  480  may provide a constant current to charge a capacitor (not shown) of charging control circuit  470 . At the same time, voltage mode control circuit  480  may increase a pulse width of pulse voltage V 1  according to the voltage across the capacitor. Pulse voltage V 1  drives voltage transforming circuit  490  to provide induced current I 1  to charge flash capacitor  460 . When flash capacitor  460  is charged completely, voltage transforming circuit  490  may provide a high voltage V 2  to prevent voltage mode PWM control circuit  480  from outputting pulse voltage V 1 . 
         [0026]    The arrangement of the invention according to this embodiment may further include a controlling circuit  444  and a switching arrangement  445 . The controlling circuit  444  may receive information about the power supply of the power source, e.g., battery  315  to the electrical components, such as the transceiver portion, of the device. During normal operation of the device, switching arrangement  445  may be controlled to supply power from the battery to all components that need electricity. If a power failure, e.g., due to a glitch, is detected, power backup controlling arrangement  444  may redirect the function of power transforming circuit  490  so that the power stored in capacitor  460  may be transformed down to a suitable level for the electrical circuits in other portions of the device. Switch arrangement  445  may be controlled to redirect the stepped-down power from flash capacitor  460  to one or more electronics of the device. 
         [0027]    By doing so, the effect of the power failure is minimized and the circuits needing power for their operation are maintained operable. 
         [0028]    The invention may detect the power glitches using a low voltage and/or current detector. A detector may be used to detect a power reduction down to a predetermined threshold value. 
         [0029]    It should be appreciated that the up/down transformation of the power to/from the capacitor may be needed where the capacitor is charged and discharged with higher voltage/current for operating the flash than other ones of the electronic components. Thus, in cases where the electronics of the device operate with same voltage current level as the capacitor, the power may be supplied to the electronics without further stepping down the power. 
         [0030]    Clearly, other capacitive elements can be used in same way as the flash capacitor. 
         [0031]    It should be noted that the word “comprising,” “comprises,” “including,” and “include” do not exclude the presence of other elements or steps than those listed and the words “a” or “an” preceding an element do not exclude the presence of a plurality of such elements. It should further be noted that any reference signs do not limit the scope of the claims, that the invention may be implemented at least in part using hardware, software, and firmware, and that several “means,” “units,” or “devices” may be represented by the same item of hardware. 
         [0032]    The above-mentioned and described embodiments are only given as examples and should not be limiting to the present invention. Other solutions, uses, objectives, and functions within the scope of the invention as claimed in the below-described patent claims, should be apparent for the person skilled in the art.