Patent Publication Number: US-2018054867-A1

Title: Power regulating circuit and liquid crystal display device

Description:
CROSS REFERENCE 
     This application claims the priority of Chinese Patent Application No. 201610028074.5, entitled “Power regulating circuit and liquid crystal display device”, filed on Jan. 15, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a display field, and more particularly to a power regulating circuit and a liquid crystal display device. 
     BACKGROUND OF THE INVENTION 
     With the development of the display technology, the liquid crystal display panel possesses properties of small volume and light weight, low power consumption. Therefore, it has been favored by the users. The liquid crystal display device generally comprises the backlight module and the liquid crystal display panel. The backlight module is employed to provide the light for the liquid crystal display panel, and the liquid crystal display panel is employed to show information of words and images. The backlight module generally comprises a light emitting unit, and the light emitting unit receives the supply voltage to emit light. According to the actual requirement, the light emitting brightness of the light emitting unit will be adjusted. However, in prior art, even the light emitting brightness of the light emitting unit is adjusted to be the disclosed brightness, the power consumption of the light emitting unit remains to be larger. Thus, it makes the energy consumption of the liquid crystal display device higher. 
     SUMMARY OF THE INVENTION 
     The present invention provides a power regulating circuit, wherein the power regulating circuit is employed to adjust a power consumption of a light emitting unit, and the light emitting unit is applied with a first supply voltage for emitting light, and the power regulating circuit comprises a brightness sensing unit, a power consumption detecting unit, a control chip and a voltage regulating unit, and the brightness sensing unit is employed to sense a brightness as the light emitting unit emits light, and the power consumption detecting unit is employed to detect a power consumption, which is a first power consumption as the light emitting unit emits light, and the control chip is employed to compare the first power consumption with a minimum power consumption of a current brightness of the light emitting unit, and as a difference of the first power consumption and the minimum power consumption is larger than a preset threshold value, the control chip controls the voltage regulating unit to decrease an amplitude of the first supply voltage and to increase a duty ratio of the first supply voltage so that the light emitting unit remains the brightness unchanged and a difference value of a power consumption of the light emitting unit and the minimum power consumption is smaller than or equal to the preset threshold value, wherein after the amplitude and the duty ratio of the first supply voltage are adjusted and in condition that the brightness of the light emitting unit is unchanged, the power consumption of the light emitting unit is the second power consumption. 
     The power consumption detecting unit comprises a multiplying unit, and the multiplying unit comprises a first multiplying input end, a second multiplying input end, a third multiplying input end and a multiplying output end, and the first multiplying input end is grounded through a first resistor, and the first multiplying input end receives a first voltage, and the second multiplying input end receives a multiplying factor, and the third multiplying input end is employed to receives an original supply voltage, and the multiplying unit obtains the first power consumption according to the first voltage, the first resistor, the original supply voltage and the multiplying factor and outputs the same through the multiplying output end. 
     The power regulating circuit further comprises a photocoupler, and the photocoupler comprises a first coupling input end, a second coupling input end, a first coupling output end and a second coupling output end, and the first coupling input end receives the original supply voltage, and the second coupling input end is coupled to the light emitting unit, and the first coupling output end receives the original supply voltage through the first resistor, and the second coupling output end is grounded through a second resistor. 
     The control chip comprises a brightness signal receiving end, a power consumption signal receiving end, a first control signal output end, a second control signal output end, and the voltage regulating unit comprises a voltage amplitude adjusting unit and a voltage duty ratio adjusting unit, and the brightness signal receiving end is electrically coupled to the brightness sensing unit, and is employed to receive a brightness signal representing the brightness as the light emitting unit emits light, and the power consumption signal receiving end is electrically coupled to power consumption detecting unit, and is employed to receive the first power consumption, and the control chips sends a first control signal and a second control signal according to the brightness signal and the first power consumption and outputs the same respectively through first control signal output end and the second control signal output end, and the voltage amplitude adjusting unit is electrically coupled to the first control signal output end, and reduces the amplitude of the first supply voltage under control of the first control signal, and the voltage duty ratio adjusting unit is electrically coupled to the second control signal output end, and increases the duty ratio of the first supply voltage under control of the second control signal. 
     The voltage amplitude adjusting unit comprises a selector, a control register and a third resistor, and the first control signal output end comprises a first sub control signal output end, a second sub control signal output end, a third sub control signal output end and a fourth sub control signal output end, and the control chip is further employed to generate a resister control signal to be outputted through the fourth sub control signal output end, and the selector comprises a first select signal input end, a second select signal input end, a third select signal input end, a first signal end, a second signal end, a third signal end, a fourth signal, a fifth signal end, a sixth signal end, a seven signal end, an eighth signal end and a select signal output end, and wherein the first signal end to the eighth signal end are respectively supplied with various reference voltages, and the first select signal input end is electrically coupled to the first sub control signal output end, and the second select signal input end is electrically coupled to the second sub control signal output end, and the third select signal input end is electrically coupled to the third sub control signal output end, and the first select signal input end, the second select signal input end and the third select signal input end are employed to receive the first control signal, and the selector selects one reference voltage on the first signal end to the eighth signal end according to the first control signal, and outputs the same through the select signal output end, and the control register comprises a first end, a second end and a first output end, and the first end is electrically coupled to the fourth sub control signal output end to receive the register control signal, and the second end is electrically coupled to the select signal output end to receive the corresponding reference voltage, and the first output end is coupled to the third resistor and grounded, and a node between the first output end and the third resistor is employed to be an output end of the voltage amplitude adjusting unit, and the control register obtains a voltage amplitude adjusting signal according to the corresponding reference voltage and the register control signal, and outputs the same through the node between the first output end and the third resistor, and the voltage amplitude adjusting signal is employed to reduce the amplitude of the first supply voltage. 
     As the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of  000 , the selector selects the reference voltage of the first signal end and outputs the same through the select signal output end; as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of 001, the selector selects the reference voltage of the second signal end and outputs the same through the select signal output end; 
     as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of  010 , the selector selects the reference voltage of the third signal end and outputs the same through the select signal output end; as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of 011, the selector selects the reference voltage of the fourth signal end and outputs the same through the select signal output end; as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of 100, the selector selects the reference voltage of the fifth signal end and outputs the same through the select signal output end; as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of 101, the selector selects the reference voltage of the sixth signal end and outputs the same through the select signal output end; as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of  110 , the selector selects the reference voltage of the seventh signal end and outputs the same through the select signal output end; as the first select signal input end, the second select signal input end and the third select signal input end sequentially receive the first control signal of  111 , the selector selects the reference voltage of the eighth signal end and outputs the same through the select signal output end. 
     The power regulating circuit further comprises a first thin film transistor, and the first thin film transistor comprises a first gate, a first source and a first drain, and an input end of the voltage duty ratio regulating unit is electrically coupled to the second control signal output end to receive the second control signal, and an output end of the voltage duty ratio regulating unit is electrically coupled to the first gate, and the first source is electrically coupled to a node between the first output end and the third resistor, and the first drain is electrically coupled to the light emitting unit. 
     The light emitting unit is a light emitting diode. 
     The brightness sensing unit is located adjacent to the light emitting unit. 
     In comparison with prior art, the brightness sensing unit in the power regulating circuit of the present invention senses a brightness as the light emitting unit emits light, and the power consumption detecting unit detects a power consumption, which is a first power consumption as the light emitting unit emits light, and as the first power consumption is compared with a minimum power consumption of a current brightness of the light emitting unit, and a difference of the first power consumption and the minimum power consumption is larger than a preset threshold value, the control chip controls the voltage regulating unit to decrease an amplitude of the first supply voltage and to increase a duty ratio of the first supply voltage so that the light emitting unit remains the brightness unchanged and a difference value of a power consumption of the light emitting unit and the minimum power consumption is smaller than or equal to the preset threshold value. After the amplitude and the duty ratio of the first supply voltage are adjusted and in condition that the brightness of the light emitting unit is unchanged, the power consumption of the light emitting unit is the second power consumption. Accordingly, the power regulating circuit of the present invention can reduce the power consumption of the light emitting unit in condition that the brightness of the light emitting unit is unchanged, and thus to decrease the energy consumption of the light emitting unit. 
     The present invention further provides a liquid crystal display device. The liquid crystal display device comprises the power regulating circuit of any one of the respective aforesaid embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to more clearly illustrate the embodiments of the present invention or prior art, the following figures will be described in the embodiments are briefly introduced. It is obvious that the drawings are merely some embodiments of the present invention, those of ordinary skill in this field can obtain other figures according to these figures without paying the premise. 
         FIG. 1  is a circuit structure diagram of a power regulating circuit according to one preferred embodiment of the present invention. 
         FIG. 2  is a specific circuit diagram of a power circuit according to one preferred embodiment of the present invention. 
         FIG. 3  is a structural diagram of a preferred embodiment according to a liquid crystal display device of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Embodiments of the present invention are described in detail with the technical matters, structural features, achieved objects, and effects with reference to the accompanying drawings as follows. It is clear that the described embodiments are part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments to those of ordinary skill in the premise of no creative efforts obtained, should be considered within the scope of protection of the present invention. 
     Please refer to  FIG. 1  and  FIG. 2 .  FIG. 1  is a circuit structure diagram of a power regulating circuit according to one preferred embodiment of the present invention;  FIG. 2  is a specific circuit diagram of a power circuit according to one preferred embodiment of the present invention. The power regulating circuit  100  is employed to adjust a power consumption of a light emitting unit  200 . The light emitting unit  200  is applied with a first supply voltage for emitting light, and the power regulating circuit  100  comprises a brightness sensing unit  110 , a power consumption detecting unit  120 , a control chip  130  and a voltage regulating unit  140 . The brightness sensing unit  110  is employed to sense a brightness as the light emitting unit  200  emits light, and the power consumption detecting unit  120  is employed to detect a power consumption, which is a first power consumption as the light emitting unit  200  emits light, and the control chip  130  is employed to compare the first power consumption with a minimum power consumption of a current brightness of the light emitting unit  200 , and as a difference of the first power consumption and the minimum power consumption is larger than a preset threshold value, the control chip  130  controls the voltage regulating unit  140  to decrease an amplitude of the first supply voltage and to increase a duty ratio of the first supply voltage so that the light emitting unit  200  remains the brightness unchanged and a difference value of a power consumption of the light emitting unit  200  and the minimum power consumption is smaller than or equal to the preset threshold value, wherein after the amplitude and the duty ratio of the first supply voltage are adjusted and in condition that the brightness of the light emitting unit  200  is unchanged, the power consumption of the light emitting unit  200  is the second power consumption. The first supply voltage is generated by a voltage supply unit  300 . Preferably, the brightness sensing unit  110  is located adjacent to the light emitting unit  200  to sense the brightness as the light emitting unit  200  emits light more accurately. 
     The power consumption detecting unit  120  comprises a multiplying unit  121 , and the multiplying unit  121  comprises a first multiplying input end  121   a,  a second multiplying input end  121   b,  a third multiplying input end  121   c  and a multiplying output end  121   d.  The first multiplying input end  121   a  is grounded through a first resistor R 1 , and the first multiplying input end  121   a  receives a first voltage VA. The second multiplying input end  121   b  receives a multiplying factor, and the third multiplying input end  121   c  is employed to receives an original supply voltage, and the multiplying unit  121  obtains the first power consumption according to the first voltage, the first resistor R 1 , the original supply voltage and the multiplying factor and outputs the same through the multiplying output end  121   d.    
     The power regulating circuit  100  further comprises a photocoupler  150 , and the photocoupler  150  comprises a first coupling input end  151 , a second coupling input end  152 , a first coupling output end  153  and a second coupling output end  154 . The first coupling input end  151  receives the original supply voltage, and the second coupling input end  152  is coupled to the light emitting unit  200 , and the first coupling output end  153  receives the original supply voltage through the first resistor R 1 , and the second coupling output end  154  is grounded through a second resistor R 2 . 
     In this embodiment, the current transmission of the photocoupler  150  is B, then, the input current of the photocoupler  150  is Ii=VA/(R 1 *B), and the original voltage received by the photocoupler  150  is marked as Vcc, and then, the first power consumption is Vcc*VA/(R 1 *B), and thus, the multiplying factor of the multiplying unit  121  is equal to 1/(R 1 *B). 
     The control chip  130  comprises a brightness signal receiving end  131 , a power consumption signal receiving end  132 , a first control signal output end  133  and a second control signal output end  134 . Correspondingly, the voltage regulating unit  140  comprises a voltage amplitude adjusting unit  141  and a voltage duty ratio adjusting unit  142 . The brightness signal receiving end  131  is electrically coupled to the brightness sensing unit  110 , and is employed to receive a brightness signal representing the brightness as the light emitting unit  200  emits light, and the power consumption signal receiving end  132  is electrically coupled to power consumption detecting unit  120 , and is employed to receive the first power consumption. The control chips  130  sends a first control signal and a second control signal according to the brightness signal and the first power consumption and outputs the same respectively through first control signal output end  133  and the second control signal output end  134 . In other words, the first control signal is outputted through the first control signal output end  133 , and the second control signal is outputted through the second control signal output end  134 . The voltage amplitude adjusting unit  141  is electrically coupled to the first control signal output end  133 , and reduces the amplitude of the first supply voltage under control of the first control signal. The voltage duty ratio adjusting unit  142  is electrically coupled to the second control signal output end  134 , and increases the duty ratio of the first supply voltage under control of the second control signal. 
     The voltage amplitude adjusting unit  141  comprises a selector  141   a,  a control register  141   b  and a third resistor R 3 . In this embodiment, the first control signal output end  133  comprises a first sub control signal output end  133   a,  a second sub control signal output end  133   b,  a third sub control signal output end  133   c  and a fourth sub control signal output end  133   d.  The control chip  130  is further employed to generate a resister control signal to be outputted through the fourth sub control signal output end  133   d.  The selector  141   a  comprises a first select signal input end A 0 , a second select signal input end Al , a third select signal input end A 2 , a first signal end P 1 , a second signal end P 2 , a third signal end P 3 , a fourth signal P 4 , a fifth signal end P 5 , a sixth signal end P 6 , a seven signal end P 7 , an eighth signal end P 8  and a select signal output end Po. The first signal end P 1  to the eighth signal end P 8  are respectively supplied with various reference voltages. In this embodiment, the first signal end P 1  is applied with the first reference voltage Vref 1 , and the second signal end P 2  is applied with the second reference voltage Vref 2 , and the third signal end P 3  is applied with the third reference voltage Vref 3 , and the fourth signal P 4  is applied with the fourth reference voltage Vref 4 , and the fifth signal end P 5  is applied with the fifth reference voltage Vref 5 , and the sixth signal end P 6  is applied with the sixth reference voltage Vref 6 , and the seven signal end P 7  is applied with the seventh reference voltage Vref 7 , and the eighth signal end P 8  is applied with the eighth reference voltage Vref 8 . The first select signal input end AO is electrically coupled to the first sub control signal output end  133   a,  and the second select signal input end A 1  is electrically coupled to the second sub control signal output end  133   b,  and the third select signal input end A 2  is electrically coupled to the third sub control signal output end  133   c,  and the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  are employed to receive the first control signal. The selector  141   a  selects one reference voltage on the first signal end P 1  to the eighth signal end P 8  according to the first control signal, and outputs the same through the select signal output end Po. The control register  141   b  comprises a first end B 1 , a second end B 2  and a first output end Bo, and the first end B 1  is electrically coupled to the fourth sub control signal output end  133   d  to receive the register control signal, and the second end B 2  is electrically coupled to the select signal output end Po to receive the corresponding reference voltage, and the first output end Bo is coupled to the third resistor R 3  and grounded, and a node between the first output end Bo and the third resistor R 3  is employed to be an output end of the voltage amplitude adjusting unit  141 . The control register  141   b  obtains a voltage amplitude adjusting signal according to the corresponding reference voltage and the register control signal, and outputs the same through the node between the first output end Bo and the third resistor R 3 , and the voltage amplitude adjusting signal is employed to reduce the amplitude of the first supply voltage. In this embodiment, the first reference voltage Vref 1 , the second reference voltage Vref 2 , the third reference voltage Vref 3 , the fourth reference voltage Vref 4 , the fifth reference voltage Vref 5 , the sixth reference voltage Vref 6 , the seventh reference voltage Vref 7  and the eighth reference voltage Vref 8  are different from one another. In one embodiment, the voltage values of the first reference voltage Vref 1 , the second reference voltage Vref 2 , the third reference voltage Vref 3 , the fourth reference voltage Vref 4 , the fifth reference voltage Vref 5 , the sixth reference voltage Vref 6 , the seventh reference voltage Vref 7  and the eighth reference voltage Vref 8  decrease in turn from the first reference voltage Vref 1  to the eighth reference voltage Vref 8 ; in another embodiment, the voltage values of the first reference voltage Vref 1 , the second reference voltage Vref 2 , the third reference voltage Vref 3 , the fourth reference voltage Vref 4 , the fifth reference voltage Vref 5 , the sixth reference voltage Vref 6 , the seventh reference voltage Vref 7  and the eighth reference voltage Vref 8  increase in turn from the first reference voltage Vref 1  to the eighth reference voltage Vref 8 . 
     As the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 000, the selector  141   a  selects the reference voltage of the first signal end P 1  and outputs the same through the select signal output end Po; as the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 001, the selector  141   a  selects the reference voltage of the second signal end P 2  and outputs the same through the select signal output end Po; as the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 010, the selector  141   a  selects the reference voltage of the third signal end P 3  and outputs the same through the select signal output end Po; as the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 011, the selector  141   a  selects the reference voltage of the fourth signal end P 4  and outputs the same through the select signal output end Po; as the first select signal input end AO, the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 100, the selector  141   a  selects the reference voltage of the fifth signal end P 5  and outputs the same through the select signal output end Po; as the first select signal input end AO, the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 101, the selector  141   a  selects the reference voltage of the sixth signal end P 6  and outputs the same through the select signal output end Po; as the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 110, the selector  141   a  selects the reference voltage of the seventh signal end P 7  and outputs the same through the select signal output end Po; as the first select signal input end A 0 , the second select signal input end A 1  and the third select signal input end A 2  sequentially receive the first control signal of 111, the selector  141   a  selects the reference voltage of the eighth signal end P 8  and outputs the same through the select signal output end Po. 
     The power regulating circuit  100  further comprises a first thin film transistor Q 1 , and the first thin film transistor Q 1  comprises a first gate G 1 , a first source S 1  and a first drain D 1 . An input end of the voltage duty ratio regulating unit  142  is electrically coupled to the second control signal output end  134  to receive the second control signal, and an output end of the voltage duty ratio regulating unit  142  is electrically coupled to the first gate G 1 , and the first source S 1  is electrically coupled to a node between the first output end Bo and the third resistor R 3 , and the first drain D 1  is electrically coupled to the light emitting unit  200 . 
     In this embodiment, the light emitting unit  200  is a light emitting diode. The light emitting diode comprises a positive electrode and a negative electrode. The first drain D 1  is electrically coupled to the negative electrode of the light emitting unit  200 . In  FIG. 2 , the amount of the shown light emitting units  200  is three, which respectively are LED 1 , LED 2  and LED 3 . The LED 1 , the LED 2  and the LED 3  are coupled in series. 
     In comparison with prior art, the brightness sensing unit  110  in the power regulating circuit  100  of the present invention senses a brightness as the light emitting unit  200  emits light, and the power consumption detecting unit  120  detects a power consumption, which is a first power consumption as the light emitting unit emits light, and as the first power consumption is compared with a minimum power consumption of a current brightness of the light emitting unit  200 , and a difference of the first power consumption and the minimum power consumption is larger than a preset threshold value, the control chip  130  controls the voltage regulating unit  140  to decrease an amplitude of the first supply voltage and to increase a duty ratio of the first supply voltage so that the light emitting unit  200  remains the brightness unchanged and a difference value of a power consumption of the light emitting unit  200  and the minimum power consumption is smaller than or equal to the preset threshold value. After the amplitude and the duty ratio of the first supply voltage are adjusted and in condition that the brightness of the light emitting unit  200  is unchanged, the power consumption of the light emitting unit  200  is the second power consumption. Accordingly, the power regulating circuit  100  of the present invention can reduce the power consumption of the light emitting unit  200  in condition that the brightness of the light emitting unit  200  is unchanged, and thus to decrease the energy consumption of the light emitting unit  200 . 
     The present invention further provides a liquid crystal display device  10 . Please refer to  FIG. 3 .  FIG. 3  is a structure diagram of a liquid crystal display device according to one preferred embodiment of the present invention. The liquid crystal display device  10  comprises the aforesaid power regulating circuit  100 . The repeated description is omitted here. In this embodiment, the liquid crystal display device  10  comprises the smart phone, the mobile internet device (MID), the electronic book, the tablet, the Play Station Portable (PSP) or Personal Digital Assistant (PDA) but not limited thereto. The liquid crystal display device  10  also can be a liquid crystal display panel or others. 
     Above are embodiments of the present invention, which does not limit the scope of the present invention. Any modifications, equivalent replacements or improvements within the spirit and principles of the embodiment described above should be covered by the protected scope of the invention.