Abstract:
The Installation is equipped with a power supply unit and a High-Definition Multimedia Interface (HDMI), this installation being able to be connected to a second HDMI device with which it can communicate by using a protocol defined in the HDMI Standard, this installation or device being able to be set in Standby or Power-down mode and to be removed from this Standby or Power-down mode by said second HDMI device via a Consumer Electronic Control (CEC) line. The installation has a Power Management Unit (PMU) arranged on the primary side of said power supply unit, this PMU having its own power supply circuit directly connected to the power supply source of this installation or device and being arranged for switching OFF the electrical energy on the secondary side of said power supply unit when this installation or device enters said Standby or Power-down mode.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention concerns an electrical installation or device having a power supply equipped with a voltage converter or transformer and a High-Definition Multimedia Interface (HDMI). 
         [0002]    In particular, the invention may be implemented in audio/video consumer electronic devices equipped with HDMI functionality, such as a digital TV set, a display or a computer screen, a DVD player, a decoder or a demodulator (Set-Top Box), in entertainment devices like electronic play stations, etc. 
       BACKGROUND OF THE INVENTION 
       [0003]    Systems with high speed, high quality audio/video interfaces have been offered in the market since shortly after the release of the HDMI standards around 2002. 
         [0004]    The general structure of such an HDMI is shown in  FIG. 1 . Video and audio information is transmitted between a “source” part  2  of a first device having a HDMI transmitter  4  (e.g. DVD player, a set top box) and a “sink” part  6  of a second device having a HDMI Receiver  8  (e.g. a display, a digital TV) over the data and signal buses TMDS Channel  0 , TMDS Channel  1 , TMDS Channel  2  and TMDS Clock Channel. System display information is exchanged over the Display Data Channel (DDC). Operating modes (including entering and leaving Standby mode) of multiple devices are controlled and associated protocol messages are exchanged over the CEC (Consumer Electronic Control) line  10 . 
         [0005]    A typical system comprising multiple devices (in particular digital TV  12 , DVD player  18  and Set Top Box  22 ) connected via HDMI is shown in  FIG. 2 . The system has a given architecture with different levels reflected by the Physical Address (PA). On the first level are the Set Top Box  22  and a PC Game Box  24  both connected to a switcher  20 . This switcher defines a second level with the DVD player  18 , both being connected to an Audio-Video Recorder (AVR)  16 . This AVR is connected to a recording device  14  which is finally connected to the Digital TV  12 . A single CEC control line connects all system devices and a determined CEC Protocol allows these devices to communicate one to another, this CEC Protocol being included as an optional part of the HDMI Standard. Individual devices are identified by physical (PA) and logical (LA) addresses that are used for allowing a first device to exchange commands with a determined second device. 
         [0006]    Decoding of CEC protocol and embedded commands is performed in each device connected to the CEC line  10 . The CEC line is thereby connected to a physical CEC interface  30  arranged in each device followed by a decoder or more generally a CEC Controller  32  as shown in  FIG. 3 . From a power supply perspective, standard HDMI-equipped systems implement power supply topologies that rely on the use of power supply subsystems or modules whereby system interfaces, system processors and display elements are powered by the secondary side of a converter. The CEC interface  30  of a first HDMI device, in particular a sink device, can be supplied by the secondary part of a second HDMI device, in particular a source device. The CEC interface is usually supplied with a voltage of 5 V. Thus, the source device which sends a command to a sink device under the CEC Protocol also provides the necessary electrical energy for supplying the CEC Interface of this sink device. 
         [0007]    In the Standby mode of a conventional HDMI installation or device at least the CEC interface  30 , the CEC controller  32  and also corresponding portions of the main system processor  34  are supplied and able to operate. The CEC controller and the system processor of each HDMI device are supplied by the secondary part  38  of the power supply unit  36  which is equipped with a voltage converter. The primary part  40  of this voltage converter is usually connected to the mains.  FIG. 3  schematically represents a digital TV with a display  44  also supplied by the power supply unit  36 . It is to be noted that this display can have its own power supply unit or use a dedicated part of the power supply  36 . 
         [0008]    In order for a first HDMI device to be removed or woken up from a Standby or Power-down mode by a second HDMI device with the help of the CEC Protocol, the first HDMI device has in the present technology the secondary part of its power supply unit at least partially supplied for supplying at least the CEC Controller. Thus, the power consumption in the Standby or Power-down mode remains relatively high first because the primary side of the power converter is supplied in this mode and secondly also because a part of the electronic circuits on the secondary side of this power converter needs to be supplied for allowing the reception, decoding and processing of at least a wake-up signal sent under the CEC Protocol, i.e. a command sent by another HDMI device. 
         [0009]    A very low energy consuming power supply architecture is disclosed in the document WO 2010/003785. It outlines an efficient power management in Standby or Power-down mode. This power supply comprises a converter defining a primary side and a secondary side for the device equipped with it. A Power Management Unit (PMU) is arranged on the primary side with its own secondary energy supply circuit directly linked to the mains. This PMU is associated with a control circuit of the converter for setting OFF this converter in a Power-down mode, in order to have a very low power consumption. However, in this Power-down mode, there is no supply of the secondary side of the converter. As a consequence, such a system cannot be used with above described standard HDMI devices having a CEC line allowing a first device to wake up a second device linked to this first device by an HDMI. 
       SUMMARY OF THE INVENTION 
       [0010]    Cumulative stand-by power consumption of HDMI equipped audio/video devices is increasing and will be very large in a near future. Thus, there is a large energy savings potential by reducing this electrical consumption to the lowest level. Since operating an HDMI involves at least two and in many cases several devices and systems, the standby energy consumption is multiplied accordingly. 
         [0011]    A main object of the present invention is to reduce the power consumption of HDMI devices in Standby or Power-down mode. 
         [0012]    The invention thus concerns an installation or device equipped with a power supply unit and a High-Definition Multimedia Interface (HDMI), this installation or device being able to be connected to a second HDMI device with which it can communicate by using a Protocol defined in the HDMI standard (HDMI Protocol), this installation or device being able to be set in Standby or Power-down mode and to be removed from this Standby or Power-down mode by said second HDMI device via a Consumer Electronic Control (CEC) line. This installation or device is characterized in that: 
         [0013]    it has a Power Management Unit (PMU) arranged on the primary side of the power supply unit, this PMU having its own power supply circuit directly connected to the power supply source of the installation or device and being arranged for switching OFF the electrical energy on the secondary side of said power supply unit when this installation or device enters said Standby or Power-down mode; 
         [0014]    the PMU is associated with CEC means on said primary side for decoding and processing at least a wake-up signal of a CEC Protocol defined in said HDMI Standard; 
         [0015]    it comprises a CEC interface which is arranged for directly communicating with said CEC means on said primary side; and 
         [0016]    the CEC interface comprises a HDMI supply domain and a PMU supply domain which are isolated from each other by a galvanic isolation, a data transfer between these HDMI and PMU domains via the CEC line being operated only through one or several non-galvanic element(s). 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The present invention will further be described in more detail in the following description with the help of the drawings, given as examples in a non-limiting way, in which: 
           [0018]      FIG. 1 , already described, schematically shows a standard HDMI structure; 
           [0019]      FIG. 2 , already described, schematically shows a typical system comprising multiple devices connected via HDMI; 
           [0020]      FIG. 3 , already described, schematically shows a standard architecture of a HDMI digital TV; 
           [0021]      FIG. 4  schematically shows a first embodiment of a HDMI digital TV according to the present invention; 
           [0022]      FIG. 5  schematically shows a second embodiment of a HDMI digital TV according to the present invention; and 
           [0023]      FIG. 6  shows a preferred embodiment of the CEC interface according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    The architecture diagram of a first embodiment of an installation or device according to the present invention is shown in  FIG. 4 . More particularly, this  FIG. 4  represents a HDMI digital TV. The supply of the display  44  can be made by a specific converter and associated circuits. 
         [0025]    According to this first embodiment, the CEC controller is arranged on the converter primary side  52  of the power supply unit  50  and controls all CEC communication between the corresponding HDMI device and other HDMI devices of the system. In a preferred variant, the electrical supply of this CEC controller is provided, at least in Standby or Power-down mode, through the secondary power supply of the Power Management Unit (PMU) arranged on the primary side of the converter, as described in document WO 2010/003785 which is enclosed by reference in the present description. Thus, this variant has no CEC controller on the secondary side of the power unit but a CEC controller incorporated in a “PMU &amp; CEC controller” electronic part  56  on the primary side which remains power supplied in Standby and Power-down mode. In a particular variant, the CEC controller is at least partially incorporated in the Micro-Controller Unit (MCU) of the PMU which is specifically arranged for decoding and processing CEC commands and data. The CEC line of the CEC Interface  58  is thus no more connected to a unit supplied by the secondary side  54  of the converter forming the power supply unit  50  but to a unit supplied by the primary side  52  of this converter, what is not conventional for a person skilled in the art. A preferred embodiment of this CEC Interface  58  will be described later on. 
         [0026]    When the system processor  34  is active, i.e. when the device is not in the Power-down mode and this system processor is power supplied by the converter secondary side  54 , CEC commands and data not directly related to power management in a first variant or to the Power-down mode in a second variant are transmitted to the system processor  34  through a standard communication protocol such SPI, I2C, UART. Opto-coupler elements are provided in the signal path/on the signal line between the CEC controller and the system processor located on the secondary side of the power supply unit. CEC commands related to power-up or power-down are directly processed by the PMU, in order to switch ON or OFF the converter secondary side  54 . CEC address allocation is also handled by the CEC controller on the converter primary side. 
         [0027]    A second embodiment of an installation or device according to the invention is shown in  FIG. 5 . A CEC receiver is arranged on the primary side  64  of the converter in the PMU supply domain and forms with the PMU a “PMU &amp; CEC Receiver” electronic part  62 . A further CEC controller  66  is arranged on the secondary side  54 . The CEC receiver and the CEC controller both are connected to the CEC interface  68 . The CEC receiver can receive power management commands coming from another HDMI device through the CEC interface  68  and it only handles such power management commands and also a “CEC address allocation” command. In a particular variant, it handles only commands requiring to power up or power down the secondary side  54  of the power supply unit  60  further to said “CEC address allocation” command. The power management commands handled by the CEC receiver are then processed by the PMU. The CEC and the PMU can be formed as a same electronic unit processing the CEC commands and managing at least power-up or power-down signals. As in the first embodiment, the CEC receiver can be at least partially incorporated in the MCU of the PMU. 
         [0028]    The CEC controller  66  on the secondary side reacts to all other commands in active mode and also to the “CEC address allocation” command. This CEC controller  66  is similar to conventional CEC controllers and is directly connected to the CEC interface  68 . The CEC receiver on the primary side and the CEC controller on secondary side must have the same address with the present CEC Protocol. It means that when a “CEC address allocation” command is handled both CEC receiver and controller shall set the given logical and physical CEC address. 
         [0029]    A preferred embodiment of the CEC interface  58  of the first embodiment of the installation or device described here-before is shown in  FIG. 6 . On one side there is the HDMI supply domain which is powered by the +5 V supply line defined as part of the HDMI standard connector. The ground (GND) connection in this domain is formed by the CEC/DDC line. The CEC line  70  supplies the data for the CEC protocol. On the other side there is the PMU supply domain which is supplied directly by the mains on line “VSUP” and the corresponding ground line GND. A PMU &amp; CEC Microcontroller  72  (MCU) is directly supplied from the mains (High Voltage) via its own secondary power supply  74  including one or more voltage reducer(s). A detailed description of such a secondary power supply for a MCU is given in the document WO 2010/003785 which is enclosed by reference in the present description. It is to be noted that the circuit on the PMU Supply domain (R 2 ,  76 ,  78 , NM 1  and R 3 ) can advantageously in a further variant be power supplied through an intermediate level of the secondary power supply  74  providing an intermediate voltage, e.g. 12 V. 
         [0030]    According to the invention, the HDMI supply domain and a PMU supply domain are isolated from each other by a galvanic isolation, a data transfer between these HDMI and PMU domains being operated only through one or several non-galvanic element(s). This is an important feature of the CEC interface according to the present invention, because this galvanic isolation protects the HDMI supply domain from a High Voltage provided to the primary side of the converter ( 50 ;  60 ). This protection is particularly useful for protecting the source unit because the HDMI supply domain of the device or installation is galvanically connected to the secondary part of the converter of such a source unit. Thus, in the first embodiment of the invention, such galvanic isolation does not protect the device or installation itself (sink unit, e.g. a digital TV) but the source unit (e.g. a DVD player) to which the device or installation of the invention is electrically connected. In the variant of  FIG. 6 , two opto-couplers  76  and  78  are arranged for transmitting data in both communication directions. Without such a galvanic isolation the phase wire from the mains could be directly connected to GND (PMU). If we connect GND (PMU) to GND (HDMI) via a galvanic path, the phase wire could be connected to the ground of the HDMI cable which is, from a safety point of view, dangerous. 
         [0031]    The CEC protocol is very slow and can be handled by a MCU of moderate computational performance. Frequency is generally 400 Hz. By default, when no device communicates on CEC line  70 , the CEC voltage is at +5 V. This voltage is guaranteed by pull-up resistor R 1  on the HDMI domain side. Each device connected to CEC line  70  has such resistor. The value of this resistor is defined in the CEC specification: 27 kOhm +/−5% or 26 kOhm +/−10% when integrated. The CEC protocol consists of sending serial encoded bits as follows: logical ‘0’ consists of driving the CEC line to 0 V (CEC/DDC GND) during 1.5 ms and release to +5 V with the help of the pull-up resistor during 0.9 ms. Logical ‘1’ consists of driving the CEC line to 0 V (CEC/DDC GND) during 0.6 ms and releasing it to +5 V with the help of the pull-up resistor during 1.8 ms. In both cases the bit transmission duration is 2.4 ms. Sampling is done in a window of +/−0.2 ms around 1.05 ms after first falling of CEC line. 
         [0032]    The MCU  72  in the PMU supply domain receives data from the CEC line  70  on input E 1  through the opto-coupler  76  (OPTO 1 ) and transistor PM 1 . When the voltage on CEC line  70  is at +5 V (logical level ‘1’) the transistor PM 1  is non-conductive, the LED in OPTO 1  is OFF and then the bi-polar element in OPTO 1  is non-conductive. Due to the pull-up resistor R 2  logical level on E 1  is at ‘1’. When the CEC line  70  is at 0 V (logical level ‘0’) the transistor PM 1  is conductive, the LED in OPTO 1  is ON and then the bi-polar element in OPTO 1  is conductive. This bi-polar element forces E 1  at logical level ‘0’. 
         [0033]    The MCU  72  in the PMU supply domain sends data to the CEC line  70  in E 2  through the transistor NM 1  and the opto-coupler  78  (OPTO 2 ). When E 2  is at logical level ‘1’ the transistor NM 1  is conductive, the LED in OPTO 2  is ON and then the bi-polar element in OPTO 2  is conductive and forces CEC line to 0 V (logical level ‘0’). When E 2  is at logical level ‘0’ the transistor NM 1  is non-conductive, the LED in OPTO 2  is OFF and then the bi-polar element in OPTO 2  is non-conductive. Thus, CEC line  70  is at +5 V (logical level ‘1’) due to the pull-up resistor R 1 . 
         [0034]    The HDMI specifications call for a maximum leakage current of 1.8 μA on the CEC line toward CEC/DDC_GND when the system is powered OFF. The opto-coupler OPTO 2  has to be OFF even if the voltage supply VSUP is floating. R 3  ensures that the transistor NM 1  is OFF when no power is supplied to VSUP. 
         [0035]    It is to be noted that a same CEC interface can be implemented in the CEC Interface  68  of the second embodiment of an installation or device previously described for the communication toward the “PMU &amp; CEC receiver” electronic part  62  ( FIG. 5 ). Such a CEC interface can be arranged in parallel with a standard interface with the CEC controller  66 . Other variants for the CEC interface  68  can be provided by a person skilled in the art wherein both interfaces to the CEC receiver and controller are combined. 
         [0036]    A specific application of the present invention, based on the second embodiment of an installation or device previously described, is outlined on the example of wake-up and standby operations of a HDMI-equipped DVD player. Waking up such a DVD player is achieved through the HDMI-defined CEC protocol. In the low power mode (Standby or Power-down mode) only the “PMU &amp; CEC Receiver” electronic part is supplied while the rest of the system is not powered. The corresponding MCU receives commands over the CEC interface to wake up the DVD player. In this case the “PMU &amp; CEC Receiver” MCU uses the same CEC logical and physical address as the DVD player main system processor (LA=4, PA=1.1.2.0). In the Power-down mode this MCU decodes the CEC protocol and reacts to CEC events that require action and/or a response from the DVD player (e.g. the “standby” or “play” commands). If such a decoded message requires the DVD player to move from its low power mode to an active mode the “PMU &amp; CEC Receiver” MCU starts up the power converter to supply the elements on the converter secondary side for operation.