KR20040039901A - Set top box with power control function - Google Patents

Abstract

PURPOSE: A set-top box having a power control function is provided to reduce power consumed by a cam module by selectively supplying the power to the cam module. CONSTITUTION: A receiving unit having a tuner(110) and a demodulating unit(120) receives a scrambled broadcasting signal, tunes a certain channel, demodulates the broadcasting signal, and transmits the demodulated broadcasting signal to a cam module(200). A signal processing unit having a demultiplexer(130) and a decoder(140) decodes the broadcasting signal descrambled in the cam module(200), and outputs the decoded broadcasting signal to an image display device. If it is unnecessary for the descrambling operation of the cam module(200) on the basis of broadcasting information included in the broadcasting signal tuned in the receiving unit, a control unit having a power control unit(160) and a switching unit(170) blocks power supplied to the cam module(200).

Description

Set top box with power control function

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a set top box, and more particularly, to supply power supplied to a conditional access module (CAM) that descrambles a scrambled broadcast signal and applies it to a set top box. It relates to a set-top box for controlling and a power control method of the set-top box.

In general, a set-top box is a device provided on a set such as a television to receive digital satellite broadcasting. The set-top box encrypts a broadcast signal in order to allow viewing only to a receiver who has a predetermined contract with a broadcasting company that transmits digital satellite broadcasting. The receiver has extra hardware to decrypt it, i.e. de-scrambling it. Such hardware is commonly referred to as a cam module. The cam module is classified into various types according to the method of scrambling the broadcast signal. For example, the cam module is designed according to the viaccess method, the nagravision method, the conax method, and the cryptoworks method, and each method is not compatible with each other. In order to eliminate such incompatibility, the set-top box mounts a cam module externally, and defines a standard interface between the cam module and the set-top box. Accordingly, the viewer only needs to connect the smart card provided by the broadcasting company to the cam module, and does not need to separately consider the scrambling method of the cam module.

On the other hand, the cam module requires a high hardware specification because it has to descramble the scrambled broadcast signal in real time, and consumes power as much as a set-top box. In addition, since the cam module generates a large amount of heat according to power consumption, there is a problem that the operation of the cam module becomes unstable during long driving.

The present invention has been made to solve the above-mentioned conventional problems, an object of the present invention is to provide a set-top box having a function of reducing the power consumption of the cam module connected to the set-top box and reduces the heat generation of the cam module.

1 is a block diagram of a set-top box and a cam module connected thereto according to the present invention;

2 is an embodiment of the power control unit shown in FIG. 1, and

3 is a flowchart illustrating a power control method of a set-top box according to the present invention.

* Description of the symbols for the main parts of the drawings *

110: tuner 120: demodulator

130: demultiplexer 140: decoder

150: microcomputer 160: power

170: power control unit 200: cam module

210: descrambler 220: slot

300: smart card

According to the present invention, in the set-top box having an interface that can be connected to the cam module for descrambling the scrambled broadcast signal, receiving the scrambled broadcast signal to tune to a predetermined channel to demodulate, and then to the cam module When the descrambling operation of the cam module is unnecessary on the basis of broadcast information inherent in a receiver for transmitting, a signal processor for decoding the descrambled broadcast signal from the cam module and outputting the decoded broadcast signal to the video display device, and the broadcast signal tuned in the receiver, It is achieved by a control unit that cuts off the power applied to the module.

Preferably, the control unit, the switching to cut off the power applied to the cam module in response to the control signal from the power control unit and the power control unit for generating a control signal when the descrambling operation of the cam module based on the selected broadcast signal is unnecessary. Contains wealth.

Preferably, the power control unit generates a control signal when the broadcast signal is a free broadcast signal, when the channel switching of the set-top box has not changed for a predetermined time, and when the set-top box is in the standby mode.

According to the present invention, a method of controlling a power supply of a set-top box having an interface connectable with a cam module for descrambling a scrambled broadcast signal, receiving a scrambled broadcast signal to tune to a predetermined channel After demodulating the data, transmitting the data to the cam module, decoding the descrambled broadcast signal from the cam module, and outputting the decoded broadcast signal to an external device, and referring to information included in the broadcast signal of the tuned channel. It is achieved by cutting off the power applied to the cam module.

Preferably, the step of blocking includes generating a control signal when the descrambling operation of the cam module is unnecessary based on the tuned broadcast signal, and cutting off power applied to the cam module in response to the control signal. .

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a block diagram of a set-top box and a cam module connected thereto according to the present invention.

The illustrated set-top box 100 includes a tuner 110, a demodulator 120, a demultiplexer 130, a decoder 140, a microcomputer (MCU) 150, a power supply 160, a switching unit 170, and a signal. It has a selector 180.

In addition, the cam module 200 illustrated has a descrambler 210 and a slot 220. In addition, the smart card 300 is removable in the slot 220.

The tuner 110 receives a digital satellite broadcast radio wave from a broadcasting station and tunes a predetermined channel by operating a setting key attached to a video display device such as a remote controller or other television from the outside.

The demodulator 120 demodulates the broadcast signal of the channel received by the tuner and converts the broadcast signal into a data stream, and the demodulated data stream is transmitted to the cam module 200.

The demultiplexer 130 receives the descrambled data from the cam module 200 and separates it into a video signal and an audio signal.

The decoder 140 decodes and outputs a video signal and an audio signal separated from the demultiplexer 130, respectively. In general, the decoder converts the video signal into R, G, and B formats, and outputs the video signal. Here, in addition to the R, G, and B formats, the video signal output format of the decoder may use a composite method, a component format, or the like.

The microcomputer (MCU) 150 controls the overall operation of the set-top box 100. That is, the microcomputer (MCU) 150 is a tuner 110, a demodulator 120, a demultiplexer 130, a decoder 140 in response to a setting key attached to a video display device such as a remote controller or other television from the outside. The operation of the switching unit 170 is controlled. For example, when the viewer presses the channel switching key with the remote control, the tuner 110 is controlled in response thereto, and when the viewer presses a setting key for changing the color to be displayed on the video display device, the decoder 140 is controlled to realize this. do. In addition, the microcomputer (MCU) 150 refers to the data stream output from the demodulator 120 and turns on / off the switching unit with the control signals En1 and / or En2 in the case of the free broadcast signal. The data stream is output to the signal selector 180 so that the data stream is applied to the demultiplexer 130.

The power source 160 is obtained by rectifying AC power from the outside or uses a built-in battery. The power supply 160 drives the set top box 100 of the present invention and supplies power to the cam module 200 associated with the set top box 100.

The switching unit 170 cuts off the power of the cam module 200 when descrambling is not required among the control signals applied to the microcomputer 150 by a remote controller or a setting key. In general, some of the broadcast signals transmitted through satellites are scrambled, and some are not scrambled. The scrambled broadcast signal is a pay broadcast signal, and the unscrambled broadcast signal is a free broadcast signal. Also, programs such as emergency news may not be scrambled. That is, when the set-top box 100 is turned on, the cam module 200 does not always need to perform a descrambling operation, and when the pay broadcasting signal is not applied to the cam module 200, the cam module 200 is applied to the cam module 200. The applied power may be turned off. Therefore, the microcomputer (MCU) 150 determines whether the pay broadcast signal or the free broadcast signal with reference to the data stream demodulated by the demodulator 120 and controls the switching unit 170 according to the result. Accordingly, since the cam module 200 operates only when a pay broadcast signal is applied, power consumption is reduced, and heat generation is stopped when a free broadcast signal is applied. In addition, the cam module 200 does not need to perform a descrambling operation even when the set top box 100 is in a standby mode. In the standby mode, when the set-top box is waiting for operation, power is supplied to the set-top box or not driven. Therefore, it is not necessary to apply power to the cam module connected to the set-top box.

The signal selector 180 applies the data stream output from the demodulator 120 to the descrambler 210 or the demultiplexer 130 of the cam module 200 in response to the control signal En3. When the control signal En3 is activated, the data stream is applied to the demultiplexer, and when the control signal En3 is deactivated, the data stream is applied to the descrambler 210.

Table 1 below shows a service information table having broadcast service information in the specification for broadcast transmission as a specification of the DVB (DVB) system of the European Telecommunication Standards Association (ETSI).

SYNTAX Nomber of bits Identifier table_id 8 uimsbf section_syntax_indicator One bslbf reserver One bslbf reserved 2 bslbf section_length 12 uimsbf transport_stream_id 16 uimsbf reserved 2 bslbf version_number 5 uimsbf currunt_next_indicator One bslbf section_number 8 uimsbf last_section_number 8 uimsbf original_network_id 16 uimsbf reserver 8 bslbf service_id reserver 16 uimsbf reserver 6 bslbf EIT_schedule_flag One bslbf EIT_present_following flag One bslbf running_status 3 uimsbf free_CA_mode One bslbf descriptor_loop_length 12 uimsbf CRC_32 32 rpchof

When free_CA_mode consisting of 1 bit is set to "0" among the broadcasting service information consisting of a total of 128 bits, it is free broadcasting, and when it is set to "1", it is paid broadcasting. That is, the set-top box determines whether it is a free broadcast or a paid broadcast by referring to a value set in free_CA_mode included in the broadcast signal, and cuts off the power applied to the cam module 200 for descrambling for free broadcast. Therefore, the microcomputer (MCU) 150 is programmed so that the power supply 160 is not applied to the cam module 200 by controlling the switching unit 170 for such a condition. When programming the microcomputer (MCU) 150, a predetermined program is embedded in the ROM (for example, EPROM, EEPROM, flash ROM, etc.) embedded in the microcomputer (MCU) 150 to implement this.

The cam module 200 has a descrambler 210 and a slot 220.

The descrambler 210 receives the data stream output from the demodulator 120, descrambles it, and outputs it to the demultiplexer 130.

The slot 220 is an interface for connecting with the removable smart card 300 from the outside and is connected with the smart card 300 to provide a part of an algorithm for descrambling. The smart card 300 has a part of the descrambling algorithm of the descrambler 210, and when attached to the cam module 200, the descrambler 210 forms a complete descrambling algorithm. Such a smart card 300 is provided to the viewers with a predetermined contract in the broadcaster.

2 illustrates an embodiment of the switching unit 170 illustrated in FIG. 1.

The illustrated switching unit 170 outputs the power supply voltage 5V to the cam module 200 in response to the first control signal En1 and the second control signal En2 output from the microcomputer (MCU) 150. Resistors 173a and 173b and bypass capacitors 174a and 174b, which are attached to the integrated circuit 171 and the integrated circuit 171, to reduce noise of the power supply voltage 5V output to the cam module 200. 175a, 175b, 176a, and 176b). Here, the bypass capacitors 172a and 172b reduce noise of the power supply voltage 5V applied to the integrated circuit 171.

The integrated circuit 171 illustrated as the linear technology LTC1478 is a power supply voltage in response to the first control signal En1 and the second control signal En2 output from the microcomputer 150, respectively. It has a switching function of supplying or interrupting 5V to an external device (for example, the cam module 200). Accordingly, upon receiving the free broadcast signal, the microcomputer (MCU) 150 transitions both the first control signal En1 and the second control signal En2 to a logic “high” and is provided in the set top box 100. Cut off the power supply to the cam module connected to the two slots. Accordingly, the switching unit 170 cuts off the power supplied to the cam module 200 when the descrambler 210 does not need to operate, so that the switching unit 170 operates in conjunction with the set top box 100. Blocks unnecessary power consumption. Thus, the heat generated in the cam module 200 is also reduced.

3 is a flowchart illustrating a power control method of the set-top box 100 according to the present invention.

First, any one of the digital satellite broadcasting signals is tuned by the tuner 110 of the set top box 100 (S110). Tuning of the broadcasting station is usually one of a remote control, a setting key attached to the set-top box 100, and a setting key attached to the video display device connected to the set-top box 100. Next, the demodulator 120 demodulates the broadcast signal tuned by the tuner 110 and converts the broadcast signal into a data stream (S120). In general, since a broadcaster modulates an MPEG signal and transmits it through a satellite, demodulating the data stream has an MPEG format (eg, MPEG-1, MPEG-2, etc.). Here, since the demodulated data stream is scrambled, the viewer who does not have a predetermined contract with the broadcaster cannot watch. Next, the microcomputer (MCU) 150 examines the data stream output from the demodulator 120 and determines whether it is a free broadcast signal or a paid broadcast signal (S210). If it is determined that the free broadcast signal, the first control signal (En1) or the second control signal (En2) is output (S210). At this time, the microcomputer (MCU) 150 activates the control signal En3 to enable the signal selector 180 and applies the demodulated data stream demodulated by the demodulator 120 to the demultiplexer 130. Here, the output control signal (for example, the first control signal En1 and the second control signal En2) is determined according to the number of slots provided in the set top box 100. Typically, the set-top box 100 has two slots for connecting the cam module, and in most cases, the cam module 200 is connected to only one of the two slots. If the result of the test of the demodulated data stream is a free broadcast signal, the cam module 200 is turned off (S310). Next, when the demodulated data stream is a pay broadcast signal, it is determined whether the set top box is in the standby mode (S220). As a result of determination, the microcomputer 150 activates the control signals En1 and / or En2 in the standby mode, and turns off the cam module. In the non-standby mode, the control signals En1 and / or The decoded broadcast signal is descrambled by deactivating En2) (S320). Accordingly, the descrambler 210 descrambles the data stream output from the demodulator 120 and outputs the descrambler 130 to the demultiplexer 130 (S320). Finally, the decoder 140 decodes the video signal and the audio signal, respectively, and outputs them to an external device (eg, a television, a PDP, a monitor, etc.) (S500). Therefore, the power control method of the set-top box 100 reduces power consumption and heat generation by cutting off the power supplied to the cam module 200 when the cam module 200 does not need to operate.

As described above, the present invention reduces power consumed by the cam module by selectively applying power to the cam module operated in conjunction with the set-top box, and may reduce heat generated by the cam module according to the reduced power. Can be.

Although the preferred embodiments of the present invention have been illustrated and described above, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention without departing from the spirit of the present invention as claimed in the claims. Anyone of ordinary skill in the art can make various modifications, as well as such changes are within the scope of the claims.

Claims (5)

A set top box having an interface connectable with an electronic circuit module for descrambling a scrambled broadcast signal, A receiver which receives the scrambled broadcast signal, tunes a predetermined channel, demodulates it, and transmits the demodulated signal to the electronic circuit module; A signal processor to decode the broadcast signal descrambled by the electronic circuit module and output the decoded broadcast signal to an image display device; And And a control unit which cuts off the power applied to the electronic circuit module when the descrambling operation of the electronic circuit module is unnecessary based on the broadcast information embedded in the broadcast signal tuned by the receiver. Set top box having. The method of claim 1, The control unit, A power controller configured to generate a control signal when the descrambling operation of the electronic circuit module is unnecessary based on the tuned broadcast signal; And And a switching unit which cuts off the power applied to the electronic circuit module in response to the control signal from the power control unit. The method of claim 2, The power control unit, And a control signal is generated when the broadcast signal is a free broadcast signal or when the set top box is in a standby mode. A method of controlling a power supply of a set top box having an interface connectable with an electronic circuit module for descrambling a scrambled broadcast signal, the method comprising: Receiving the scrambled broadcast signal, tuning a predetermined channel, demodulating it, and transmitting the demodulated channel to the electronic circuit module; Decoding each of the descrambled broadcast signals in the electronic circuit module and outputting the decoded broadcast signals to an external device; And And cutting off power applied to the electronic circuit module when an operation of the electronic circuit module is unnecessary by referring to information included in the broadcast signal of the tuned channel. The method of claim 4, wherein The blocking step, Generating a control signal when the descrambling operation of the electronic circuit module is unnecessary based on the tuned broadcast signal; And And shutting off power applied to the electronic circuit module in response to the control signal.