Patent Publication Number: US-2012044142-A1

Title: Display having auto-off function by person infrared sensing

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a display. More particularly, the present invention relates to a display having an auto-off function by person infrared sensing. 
     2. Description of the Related Art 
     Presently, a computer usually has a power management system for providing a power saving control function. For instance, when the computer host senses no operation input from a mouse or keyboard for a predetermined period of time, the host turns off the computer display and then the display enters a standby mode. Only when the host senses some operation input from the mouse or keyboard, the host turns on the display again and then the display returns to a normal mode. In the standby mode, the display turns off most function modules to save significant power consumption and maintains few function modules to offer, for example, remote control and digital clock functions to avoid having to wait for the display to reboot or reset. In the normal mode, the display turns on all or most function modules. 
     However, when a person uses the computer to work, if the person reads paper documents and hence no operation is input to the computer for the predetermined period of time, the host will also turn off the display and then the display enters the standby mode. If the person changes his/her sight to the display, the person will have to stop working and do some operation input through the mouse or keyboard to awake the display so as to interrupt the person&#39;s work. Accordingly, the person usually tends to turn off the power saving control function to avoid frequent interrupts. After turning off the power saving control function, the person usually forgets to turn on the power saving control function again or turn off the display before leaving the computer. It results in a waste of power and fails to achieve power saving. 
     SUMMARY OF THE INVENTION 
     Accordingly, a display is provided for being automatically turned to control the display to enter a direct-current (DC) off mode when sensing a person leaving the display for a predetermined period of time. In the DC off mode, the display turns off its internal DC power supply to turn off all function modules to save the most power consumption. 
     According to an aspect of the present invention, a display having an auto-off function by person infrared sensing includes a display unit, an infrared sensor module, a control unit and a power supply unit. The display unit displays images. The infrared sensor module senses whether or not a person is within a zone surrounding the display, and generates a sensing trigger signal when sensing no person within the zone. The control unit is coupled to the display unit and the infrared sensor module. The control unit includes a processor, and the processor stops outputting a control signal when keeping on receiving the sensing trigger signal for a predetermined period of time. The power supply unit is coupled to the display unit and the control unit. The power supply unit supplies power to the control unit or to the display unit and the control unit when receiving the control signal, and enters a DC off mode to stop supplying power when not receiving the control signal. 
     The present invention applies the person infrared sensing technology to the display so that the display is automatically turned off to enter the DC off mode when sensing no person within the zone surrounding the display (that is, the person leaving the display) for the predetermined period of time so as to achieve power saving and avoid the above-mentioned frequent interrupts. In addition, when the display enters the DC off mode, the person must manually turn on the display by, for example, pressing a power button disposed on the display or a remote controller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features of the disclosure will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which: 
         FIG. 1  is a schematic block diagram illustrating an embodiment of a display having an auto-off function by person infrared sensing according to the present invention; 
         FIG. 2  is a schematic diagram illustrating an embodiment of the infrared sensor module shown in  FIG. 1 ; 
         FIG. 3  is a flowchart illustrating an embodiment of a method for automatically turning off a display by person infrared sensing according to the present invention; 
         FIG. 4  is a flowchart illustrating another embodiment of a method for automatically turning off a display by person infrared sensing according to the present invention; and 
         FIG. 5  is a schematic block diagram illustrating another embodiment of a display having an auto-off function by person infrared sensing according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is a schematic block diagram illustrating an embodiment of a display having an auto-off function by person infrared sensing according to the present invention, in which solid lines with arrows are power lines, and dashed lines with arrows are signal lines. Referring to  FIG. 1 , a display  1  having an auto-off function by person infrared sensing is, for example, a liquid crystal display (LCD) television, an LCD monitor or an all-in-one computer. The display  1  includes a power supply unit (PSU)  11 , a control unit (CU)  12 , a display unit (DU)  13  and an infrared sensor module (ISM)  14 . The power supply unit  11  includes an input rectifying and filtering circuit  111 , a DC to DC converter  112 , a control circuit  113  and an inverter  114 . The control unit  12  includes a DC to DC converter  121 , a processor  122  and an on-screen display (OSD) module  123 . The display unit  13  includes a backlight module  131  and a LCD panel  132 . 
     In the power supply unit  11 , the input rectifying and filtering circuit  111  includes, for example, an electromagnetic interference filter, a bridge rectifier and an electrolytic capacitor of large capacitance. The input rectifying and filtering circuit  111  receives an alternating-current (AC) supply voltage VAC input (such as 90 Vrms-264 Vrms) and converts the AC supply voltage VAC into a first DC supply voltage VDC 1 . The DC to DC converter  112  employs, for example, a full-bridge or half-bridge DC to DC converter. 
     The DC to DC converter  112  is coupled to the input rectifying and filtering circuit  111 . The DC to DC converter  112  converts the first DC supply voltage VDC 1  into a plurality of second DC supply voltages VDC 21 -VDC 23 . The second DC supply voltages VDC 21  and VDC 22  (such as 5V and 12V, respectively) supply power to the control unit  12 . The second DC supply voltage VDC 23  (such as 12V-36V) is further converted into a backlight supply voltage VBLU by the inverter  114  to supply power to the display unit  13 . 
     The control circuit  113  is coupled to the input rectifying and filtering circuit  111  and supplied power from the first DC supply voltage VDC 1 . The control circuit  113  is further coupled to the DC to DC converter  112  and the processor  122 . When the control circuit  113  receives a control signal CTRL outputted from the processor  122 , the control circuit  113  controls, according to the control signal CTRL, the DC to DC converter  112  to cause the power supply unit  11  to enter a standby mode to supply power to the control unit  12  or to enter a normal mode to supply power to the control unit  12  and the display unit  13 . When the control circuit  113  does not receive the control signal CTRL, the control circuit  113  does not control the DC to DC converter  112  anymore to cause the power supply unit  11  to enter a DC off mode to stop supplying power. 
     In the control unit  12 , the DC to DC converter  121  converts the second DC supply voltages VDC 21  and VDC 22  provided from the power supply unit  11  into a plurality of DC supply voltages to supply power to the internal components of the control unit  12  such as the processor  122  and the OSD module  123 . In this embodiment, the DC to DC converter  121  further converts to generate a plurality of third DC supply voltages VDC 31  and VDC 32  (such as 3.3V and 5V, respectively). The third DC supply voltage VDC 31  supplies power to the infrared sensor module  14 , and the third DC supply voltage VDC 32  supplies power to the LCD panel  132 . 
     The processor  122  is, for example, a micro control unit (MCU). When the power supply unit  11  enters the normal mode, the processor  122  controls the DC to DC converter  121  and controls the DC to DC converter  112  through the control circuit  113  to supply power to the control unit  12  and the display unit  13 . When the processor  122  keeps on receiving a sensing trigger signal SEN for a predetermined period of time, the processor  122  stops outputting the control signal CTRL and then the power supply unit  11  enters the DC off mode to stop supplying power. 
     Because the infrared sensor module  14  senses whether or not a person is within a zone surrounding the display  1  and generates the sensing trigger signal SEN when sensing no person within the zone, once the processor  122  receives the sensing trigger signal SEN, the processor  122  can determine that no person is within the zone and start to count time until it does not receive the sensing trigger signal SEN anymore. When the processor  122  keeps on receiving the sensing trigger signal SEN for the predetermined period of time, the processor  122  can determine that no person is within the zone for the predetermined period of time. Accordingly, the processor  122  stores the display settings such as brightness and contrast settings, and then controls the DC to DC converter  121  to stop supplying power to the LCD panel  132  and outputs the control signal CTRL to the control circuit  113  to control the DC to DC converter  112  to turn off the backlight module  131 , and finally stops outputting the control signal CTRL. When the control circuit  113  does not receive the control signal CTRL, the control circuit  113  does not control the DC to DC converter  112  anymore to cause the power supply unit  11  to enter the DC off mode to stop supplying power. 
     In one embodiment, when the processor  122  does not keep on receiving the sensing trigger signal SEN for the predetermined period of time and no image is input for a preset period of time, the processor  122  controls the DC to DC converter  121  to stop supplying power to the LCD panel  132 , and outputs the control signal CTRL to the control circuit  113  to control the DC to DC converter  112  to cause the power supply unit  11  to enter the standby mode. Accordingly, the inverter  114  cannot obtain sufficient power from the DC to DC converter  112  so as to enter a protection state to stop providing the backlight supply voltage VBLU. Therefore, the display unit  13  are turned off in whole. 
     The OSD module  123  provides a user interface for the person to set the predetermined period of time and/or whether or not the auto-off function is activated. If the person sets that the auto-off function is not activated, the processor  122  will ignore the sensing trigger signal SEN when receiving the sensing trigger signal SEN. 
     In the display unit  13 , the backlight module  131  provides light for the LCD panel  132  to display images. In this embodiment, the backlight module  131  employs, but not limited to, cold cathode fluorescent lamps (CCFLs) as a backlight source of the backlight module  131 , and accordingly the inverter  114  is required to convert the second DC supply voltage VDC 23  into the high-voltage AC backlight supply voltage VBLU to supply power to the backlight module  131 . In an alternative embodiment, the backlight module  131  can employ light-emitting diodes (LEDs) as the backlight source, and accordingly a DC to DC converter is required to replace the inverter  114  to convert the second DC supply voltage VDC 23  into a low-voltage DC backlight supply voltage VBLU to supply power to the backlight module. 
       FIG. 2  is a schematic diagram illustrating an embodiment of the infrared sensor module  14  shown in  FIG. 1 . Referring to  FIG. 2 , the infrared sensor module  14  includes a passive infrared sensor (PIR) A 1 , an amplifying and filtering circuit IC 1  and a transistor Q 1 . The passive infrared sensor A 1  senses person&#39;s infrared radiation to determine whether or not a person is within the zone. The amplifying and filtering circuit IC 1  is, for example, an integrated circuit PS 204  having a positive supply terminal VDD, a supply ground terminal VSS, a sensor input  1  terminal IN 1 , a sensor input  2  terminal IN 2 , a day/night mode select terminal OEN, a sensitivity terminal SENS, a timer terminal ONTIME and a relay out terminal REL. 
     The positive supply terminal VDD and the supply ground terminal VSS are coupled to the third DC supply voltage VDC 31  and ground, respectively, so that the third DC supply voltage VDC 31  supplies power to the amplifying and filtering circuit IC 1 . When a person is within the zone, the passive infrared sensor A 1  generates a sensing current, and then the sensing current flows through a resistor R 1  to be converted into a corresponding sensing voltage. The sensing voltage is filtered by a resistor R 2  and a capacitor C 1  and input to the sensor input  1  terminal IN 1  and the sensor input  2  terminal IN 2 . The amplifying and filtering circuit IC 1  employs a differential input stage to amplify the filtered sensing voltage and outputs a high-level signal from the relay out terminal REL to turn on the transistor Q 1  through resistors R 5  and R 6  so that the voltage level of the sensing trigger signal SEN is low and represents to output the sensing trigger signal SEN. When no person is within the zone, the amplifying and filtering circuit IC 1  outputs a low-level signal from the relay out terminal REL to turn off the transistor Q 1  through resistors R 5  and R 6  so that the voltage level of the sensing trigger signal SEN is high and represents not to output the sensing trigger signal SEN. The threshold voltage of determining the sensing voltage can be set by selecting a resistance of a resistor R 3 , and a period of time of the relay out terminal REL output staying active can be set by selecting a resistance of a resistor R 4 . 
       FIG. 3  is a flowchart illustrating an embodiment of a method for automatically turning off a display by person infrared sensing according to the present invention, in which the method is adapted for the display  1  shown in  FIG. 1 . Referring to  FIGS. 1 and 3 , a method for automatically turning off the display  1  by person infrared sensing includes three stages related to the power supply unit  11 , the infrared sensor module  14  and the processor  122 . A person turns on the power supply unit  11  to enter the normal mode by, for example, manually pressing a power button disposed on the display  1  or a remote controller (Step S 31 ). In the normal mode, the power supply unit  11  supplies power to the control unit  12 , the display unit  13  and the infrared sensor module  14 , in which the infrared sensor module  14  is indirectly supplied power from the power supply unit  11  through the display unit  13  as shown in  FIG. 1  (Step S 32 ). 
     The infrared sensor module  14  starts to work and senses whether or not a person is within the zone surrounding the display  1  (Step S 33 ). Because the person who presses the power button is sure to exist within the zone surrounding the display  1 , the infrared sensor module  14  will sense that there is a person within the zone until the person&#39;s first time to leave the zone. When the infrared sensor module  14  senses no person within the zone, the infrared sensor module  14  generates the sensing trigger signal SEN sent to the processor  122  (Step S 34 ). 
     The processor  122  determines whether or not the auto-off function is activated (Step S 35 ). When the recent display setting indicates that the person uses the user interface provided by the OSD module  123  to set that the auto-off function is not activated, the processor  122  will ignore the sensing trigger signal SEN generated by the infrared sensor module  14  (Step S 36 ) and then the process returns to Step S 32  to go on. When the recent display setting indicates that the person sets that the auto-off function is activated, the processor  122  determines whether or not it keeps on receiving the sensing trigger signal SEN (i.e. sensing no person within the zone) for the predetermined period of time (Step S 37 ). 
     When the processor  122  determines that it does not keep on receiving the sensing trigger signal SEN for the predetermined period of time, it represents that no person is within the zone and the period of time of no person within the zone does not exceed the predetermined period of time yet so that the process returns to Step S 32  to go on. When the processor  122  determines that it keeps on receiving the sensing trigger signal SEN for the predetermined period of time, it represents that no person is within the zone and the period of time of no person within the zone exceeds the predetermined period of time so that the processor  122  stores the display settings and then controls the DC to DC converter  121  to stop supplying power to the LCD panel  132  and outputs the control signal CTRL to the control circuit  113  to control the DC to DC converter  112  to turn off the backlight module  131  (Step S 38 ), and finally stops outputting the control signal CTRL (Step S 39 ). When the control circuit  113  does not receive the control signal CTRL, the control circuit  113  does not control the DC to DC converter  112  anymore to cause the power supply unit  11  to enter the DC off mode to stop supplying power to the control unit  12 , the display unit  13  and the infrared sensor module  14  (Step S 40 ), and accordingly the person must press the power button (Step S 31 ) if the person wants to turn on the display  1  again. 
       FIG. 4  is a flowchart illustrating another embodiment of a method for automatically turning off a display by person infrared sensing according to the present invention, in which the method is adapted for the display  1  shown in  FIG. 1 . Referring to  FIGS. 3 and 4 , a method shown in  FIG. 4  and the method shown in  FIG. 3  differs in “N” path at Step S 37 . Referring to  FIGS. 1 and 4 , when the processor  122  determines that it does not keep on receiving the sensing trigger signal SEN for the predetermined period of time, it represents that the period of time of no person within the zone does not exceed the predetermined period of time yet so that the processor  122  further determines whether or not no image is input for the preset period of time (Step S 41 ). 
     When the processor  122  determines that no image is input and the period of time of no image input does not exceeds the preset period of time, the process returns to Step S 33  to go on. When the processor  122  determines that no image is input for the preset period of time, it represents that although the period of time of no person does not exceed the predetermined period of time, but the period of time of no image input exceeds the preset period of time so that the display  1  is almost in idle. Accordingly, the processor  122  turns off the input/output of unessential modules of the control unit  12  (such as the OSD module  123 ), controls the DC to DC converter  121  to stop supplying power to the LCD panel  132  and outputs the control signal CTRL to the control circuit  113  to control the DC to DC converter  112  to cause the power supply unit  11  to enter the standby mode. The inverter  114  cannot obtain sufficient power from the DC to DC converter  112  so as to enter a protection state to stop providing the backlight supply voltage VBLU so that the display unit  13  is turned off in whole (Step S 42 ). Then, the power supply unit  11  enters the standby mode to only supply power to essential modules of the control unit  12  (such as the processor  122 ) and the infrared sensor module  14  (Step S 43 ), and the process returns to Step S 33  to go on. 
       FIG. 5  is a schematic block diagram illustrating another embodiment of a display having an auto-off function by person infrared sensing according to the present invention. Referring to  FIGS. 1 and 5 , a display  5  shown in  FIG. 5  and the display  1  shown in  FIG. 1  differ in how to supply power to the infrared sensor module  14 . In the display  1 , the DC to DC converter  121  converts the second DC supply voltage VDC 21  or VDC 22  into the third DC supply voltage VDC 31  to supply power to the infrared sensor module  14 . In the display  5 , the infrared sensor module  14  is further coupled to the power supply unit  11  and supplied power from the second DC supply voltage VDC 21 . Therefore, the infrared sensor module  14  of the display  1  is directly supplied power from the control unit  12  or indirectly supplied power from the power supply unit  11  through the control unit  12 , and the infrared sensor module  14  of the display  5  is directly supplied power from the power supply unit  11 . 
     In summary, the present invention applies the person infrared sensing technology to the display so that the display is automatically turned off to enter the DC off mode when sensing no person within the zone surrounding the display (that is, the person leaving the display) for the predetermined period of time so as to achieve power saving and avoid the above-mentioned frequent interrupts. In addition, when the display enters the DC off mode, the person must manually turn on the display by, for example, pressing a power button disposed on the display or a remote controller. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.