Patent Publication Number: US-9420657-B2

Title: Flat panel electronic device and current control system thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Chinese Patent Application No. 201210441779.1, filed on Nov. 7, 2012, which is hereby incorporated by reference in its entirety. 
     FIELD OF INVENTION 
     The present invention relates generally to the field of electronics and, in particular, to a flat panel electronic device and a current control system thereof. 
     BACKGROUND 
     The life of the battery of a flat panel electronic device (including a tablet, a flat panel mobile phone, etc.) is one of the most critical problems encountered by the users. The key factor affecting the life of the battery lies in whether the peak current in the main circuit in use exceeds the maximum allowable discharge current or not. The peak current in the main circuit exceeding the maximum allowable discharge current can have a serious effect on the life of the battery. It can also lead to the permanent damage of the battery. 
     The power capping mechanism of flat panel electronic devices in the prior art usually reduces the peak current by reducing the frequencies of the processor and the communication chip. But reducing the frequencies of the processor and the communication chip will cause the processing speed to reduce and the response time to extend, which is unacceptable to users. Further, reducing the frequencies of the processor and the communication chip requires a complicated calculation process, which needs a processing time from about tens of milliseconds to about hundreds of milliseconds. During this processing time, the battery can be damaged irreversibly. 
     Therefore, there is a need for providing a flat panel electronic device and a current control system thereof to solve the above discussed problem in the prior art. 
     SUMMARY OF THE INVENTION 
     In order to solve the above problem, a current control system of a flat panel electronic device is provided according to one aspect of the present invention, which comprises: a detecting module for detecting a current in a main circuit of the flat panel electronic device; and a control mechanism for reducing a brightness level of a backlight unit of the flat panel electronic device when the current in the main circuit is larger than or equal to a threshold so that the current in the main circuit is reduced to be less than the threshold. 
     Preferably, the control mechanism comprises a comparator for comparing a detection signal of the current in the main circuit with a threshold signal; and a backlight regulator for regulating the brightness level of the backlight unit according to a comparison result. 
     Preferably, the control mechanism further comprises an amplifying circuit, the detection signal is the signal amplified by the amplifying circuit. 
     Preferably, the threshold comprises a first threshold and a second threshold, the first threshold is smaller than the second threshold, the control mechanism controls the backlight unit to reduce to a first brightness level when the current in the main circuit is larger than or equal to the first threshold and less than the second threshold, and the control mechanism controls the backlight unit to reduce to a second brightness level when the current in the main circuit is larger than or equal to the second threshold, wherein the second brightness level is lower than the first brightness level. 
     Preferably, the control mechanism regulates the brightness level of the backlight unit to a standard brightness level when the current in the main circuit detected by the detecting module is less than the threshold in a predetermined time interval. 
     Preferably, the predetermined time interval is 5˜10 s. 
     Preferably, the detecting module is connected to the main circuit of the flat panel electronic device in parallel, and the detecting module obtains the current in the main circuit by detecting a branch current. 
     Preferably, the detecting module is a current sensing resistor. 
     Preferably, the control mechanism reduces the brightness level of the backlight unit by reducing the current of the backlight unit. 
     In another embodiment, a flat panel electronic device, having a current control system, is disclosed. The current control system comprises a detecting module for detecting a current in a main circuit of the flat panel electronic device. It also comprises a control device for reducing a brightness level of a backlight unit of the flat panel electronic device when the current in the main circuit is larger than or equal to a threshold so that the current in the main circuit is reduced to be less than the threshold. 
     The current control system provided by the present invention reduces the current in the main circuit by reducing the brightness level of the backlight unit, and the control mode thereof is simple. Therefore, it is able to reduce the processing time by more than 10 ms compared with the prior art, and the fast and effective response is an important factor for extending the life of the battery. In addition, the current control system provided by the present invention has other advantages, e.g., low number of components, simple structure, etc. 
     The embodiments mentioned in this summary of the invention will be further described in more detail in the detailed description. The summary of the invention neither implies that it is intended to limit the essential features and necessary technical features of the technical solution to be protected, nor implies that it is intended to define the protection scope of the technical solution to be protected. 
     Advantages and features of the present invention will be described in detail below in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the advantages of the invention will be readily understood, a more detailed description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings. In the drawings, 
         FIG. 1  is a schematic block diagram of the current control system used in a flat panel electronic device according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following discussion, details are presented so as to provide a more thorough understanding of the present invention. However, the present invention may be implemented without one or more of these details as would be apparent to one of ordinary skill in the art. Certain examples are illustrated without elaborate discussion of technical features that would be within the purview of one of ordinary skill in the art so as to avoid confusion with the present invention. 
     According to one aspect of the present invention, a current control system of a flat panel electronic device (hereinafter referred to as current control system) is provided.  FIG. 1  is a schematic block diagram of the current control system applied to the flat panel electronic device. As shown in  FIG. 1 , the current control system comprises a detecting means  110  and a control means  120 . 
     The detecting means  110  is used to detect a current in a main circuit of the flat panel electronic device. The detecting means  110  may detect the current in the main circuit  111  directly. As an example, the detecting means  110  may be connected to the main circuit  111  in series, as shown in  FIG. 1 , so as to detect the current in the main circuit. The detecting means  110  may also obtain the current in the main circuit by detecting ½, ⅓rd, ¼th, ⅕th, ⅙th, 1/7th, ⅛th, 1/9th or 1/10th of the current in the main circuit, etc. Alternatively, in one embodiment, by way of example, the detecting means  110  may be connected to the main circuit  111  of the flat panel electronic device in parallel, as shown in  FIG. 1 , and obtain the current in the main circuit by detecting a branch current. In a different embodiment, detecting means  110  may also obtain the current in the main circuit by detecting the current of another electronic element, which may be in proportion to the current in the main circuit. The detecting means  110  may detect the current in the main circuit of the flat panel electronic device in real time, or detect the current in the main circuit at a predetermined time interval. The predetermined time interval may be set to factory default levels or be set by the user according to an actual situation. 
     The control means  120  reduces a brightness level of a backlight unit  130  of the flat panel electronic device when the current in the main circuit is larger than or equal to a threshold so that the current in the main circuit is reduced to be less than the threshold. The control means  120  may be integrated into a main control unit of the flat panel electronic device, or be configured independently. The control means  120  may reduce the brightness level of the backlight unit  130  by reducing the current of the backlight unit  130 . The control means  120  may also regulate the brightness level of the backlight unit  130  by regulating the duty ratio of the current. Preferably, the control means  120  reduces the brightness level of the backlight unit  130  by reducing the current of the backlight unit  130  so that the current in the main circuit is reduced to be less than the threshold quickly and effectively. The threshold may be set to be equal to the maximum allowable discharge current of the battery, or less than the maximum allowable discharge current of the battery. Those skilled in the art would know to set the threshold according to the performance of the battery and the lowest brightness level of the backlight unit suitable for the users. 
     Preferably, the detecting means  110  may be a current sensing resistor  112 . The current sensing resistor is connected to the circuit to be detected in series, and the current sensing resistor achieves the detection by converting the current into a voltage signal. The resistance value of the current sensing resistor is low, and therefore, it may avoid increasing the power consumption of the flat panel electronic device, and also avoid too much heat from being produced and accumulating in the flat panel electronic device. Furthermore, the precision of the current sensing resistor is relatively high, and the precision is generally less than ±1% or even less than ±0.01% at the higher requirement. Therefore, the current sensing resistor may detect the current in the main circuit accurately and precisely so as to avoid a situation where the instantaneous current in the main circuit exceeds the maximum allowable discharge current, but it is not detected by the detecting means  110 . 
     the instantaneous current in the main circuit exceeds the maximum allowable discharge current, but it is not detected by the detecting means  110 . 
     According to one embodiment of the present invention, the control means  120  may comprises a comparator  121  and a backlight regulator  122 . The comparator  121  compares a detection signal of the current in the main circuit with a threshold signal. The threshold signal may be a signal representing the threshold when the detecting means  110  detects the current in the main circuit directly and sends it to the comparator  121 . The threshold signal may be a signal representing the corresponding ratio of the threshold when the detecting means  110  detects the branch current and sends it to the comparator  121 . For example, the threshold signal may be a signal representing 1/10 th  of the threshold when the branch current detected by the detecting means  110  is 1/10 th  of the current in the main circuit. After comparing the detection signal with the threshold signal, the comparator  121  may send the compared results to the backlight regulator  122 . The backlight regulator  122  regulates the brightness value of the backlight unit  130  according to the compared result. The backlight regulator  122  reduces the brightness level of the backlight unit  130  when the compared result indicates that the current in the main circuit is larger than the threshold. 
     Preferably, the control means  120  further comprises an amplifying circuit  123 . In this case, the detection signal sent to the comparator  121  is the signal amplified by the amplifying circuit  123 . The amplifying circuit  123  amplifies the signal received from the detecting means  110  and sends it to the comparator  121 , and thus it is convenient for the comparator  121  to compare. For example, when the detecting device  110  detects the branch current which may be 1/10 th  of the current in the main circuit or smaller, it may detect the deviation easily if the branch current is directly compared with 1/10 of the threshold. To be noted, if the current detected by the detecting means  110  is amplified by the amplifying circuit  123 , the threshold signal to be compared in the comparator  121  also needs to be adjusted correspondingly. 
     Preferably, the threshold comprises a first threshold  113  and a second threshold  114 , wherein the first threshold is smaller than the second threshold. For example, the first threshold may be ¾th of the second threshold. The control means  120  controls the backlight unit  130  to reduce to a first brightness level which is relatively brighter than a second brightness level, when the current in the main circuit is larger than or equal to the first threshold and less than the second threshold. And, the control means  120  controls the backlight unit  130  to reduce to a second brightness level which is relatively darker than a first brightness level, when the current in the main circuit is larger than or equal to the second threshold. The control means  120  may estimate which one of the three following cases the current in the main circuit detected by the detecting means  110  belongs to: smaller than the first threshold, in the range of the first threshold to the second threshold, or larger than the second threshold. The control means  120  would not operate and the brightness level of the back light unit  130  would still be the standard brightness level when the current in the main circuit is estimated to be smaller than the first threshold, the brightness level of the back light unit  130  would be regulated to the first brightness level when the current in the main circuit is estimated to be in the range of the first threshold to the second threshold, and the brightness level of the back light unit  130  would be regulated to the second brightness level when the current in the main circuit is estimated to be larger than the second threshold. 
     Preferably, the control means  120  regulates the brightness level of the backlight unit  130  to the standard brightness level when the current in the main circuit detected by the detecting means  110  is less than the threshold for a predetermined time interval. The peak current of the flat panel electronic device is generally in instantaneous state. The control means  120  ensures that the peak current does not exceed past the threshold level temporarily during the predetermined time interval. The brightness level of the backlight unit  130  is regulated to the standard brightness level to restore the normal use of the flat panel electronic device when the control means  120  estimates that the current in the main circuit is less than the threshold during the predetermined time interval. Preferably, the predetermined time interval may be 5˜10 s. The time interval of 5˜10 s is a suitable time period for estimating whether the flat panel electronic device is running steadily or not. 
     As mentioned above, the detecting means  110  may be connected to the main circuit of the flat panel electronic device in series to detect the current in the main circuit directly, and the detecting means  110  may also be connected to the main circuit of the flat panel electronic device in parallel, so as to detect the branch current and then obtain the current in the main circuit. Preferably, the detecting means  110  is connected to the main circuit of the flat panel electronic device in parallel, and consequently the power consumption and the heat produced by the detecting means  110  can be reduced. 
     A flat panel electronic device is further provided according to another aspect of the present invention. The flat panel electronic device has any current control system as mentioned above. Each component contained in the current control system as well as their connecting relation may refer to the description of the respective part above. Therefore, it is no longer described in detail in the present invention for the sake of simplicity. 
     The current control system provided by the present invention reduces the current in the main circuit by reducing the brightness level of the backlight unit, and the control mode thereof is simple. Therefore, it is able to reduce the processing time by more than 10 ms compared with the prior art, and the fast and effective response is an important factor for extending the life of the battery. In addition, the current control system provided by the present invention has advantages of low number components, simple structure and so on. 
     The present invention has been described by the above-mentioned embodiments. However, it will be understand that the above-mentioned embodiments are for the purpose of demonstration and description and not for the purpose of limiting the present to the scope of the described embodiments. Moreover, those skilled in the art could appreciate that the present invention is not limited to the above mentioned embodiments and that various modifications and adaptations in accordance of the teaching of the present invention may be made within the scope and spirit of the present invention. The protection scope of the present invention is further defined by the following claims and equivalent scope thereof.