JP2005109911A - Digital broadcasting receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the power consumption of a television receiver. <P>SOLUTION: An error detecting part 121 detects an error rate S in an error correcting part 103, and when the error rate S is not higher than a reference value Sth that can be regarded as a satisfactory receiving state, power is fed to each part of the receiver. When the error rate S is higher than the reference value Sth, a receiving state is determined to be poor, and power feedings to an MPEG demodulating part 104 for performing processing of a TS packet processed by the error correcting part 103, a speaker 13, and a liquid crystal device 4 are interrupted. In addition, power feedings to a channel selecting part 101, an OFDM (orthogonal frequency division multiplex) demodulating part 102, and the error correcting part 103 are intermittently performed to reduce power consumption and monitor the recovery state of a receiving state, and when the error rate S becomes equal to or less than the reference value Sth again, the receiving state is determined to be returned to a satisfactory state to restart the power feedings to each part, and switching is made to a state that a normal receiving operation is possible. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a digital broadcast receiver that receives digital television broadcasts and the like, and more particularly, to a digital broadcast receiver designed to reduce power consumption.

Conventionally, in wireless communication devices, power consumption has been reduced. In particular, in mobile wireless communication devices, batteries are often used as power sources, and power consumption is directly related to battery life. Reduction of power consumption has become an important issue.
As a method for reducing the power consumption, for example, in a cellular phone, the received signal level is intermittently monitored, and when the received signal level is equal to or lower than a predetermined value, it is determined that the area is an unreceivable area. By intermittently supplying power to the device, the power consumption is reduced (for example, Patent Document 1), or the electric field level of the received signal is set in three stages, and continuous reception is performed in a strong electric field. A radio receiver that avoids so-called head breaks and reduces power consumption by performing intermittent reception with a short pause in a weak electric field and intermittent reception with a long pause in a non-electric field (for example, Patent Document 2). Has been proposed.
JP-A-5-130012 JP 11-317678 A

  However, as described in Patent Document 1 or Patent Document 2 described above, when the electric field level of the received signal is used as a determination criterion for determining that the signal is in a good reception state, it is caused by a change in the electric field level. With regard to changes in the reception status, the reception status can be accurately determined, but if the received signal has a sufficient electric field level, multipath interference, image frequency interference, intermodulation interference, etc. occur. The reception quality may be deteriorated. As described above, when the electric field level is used as the determination criterion of the reception state, when a reception state defect due to factors other than the electric field level occurs, Cannot be detected.

For this reason, although it is actually not in a good reception state, it is determined that the reception state is good. During this time, power consumption cannot be reduced and wasteful power consumption is performed. There is a problem of end.
Accordingly, the present invention has been made paying attention to the above-mentioned conventional unsolved problems, and can determine the reception state accurately and accordingly can reduce the power more accurately. The purpose is to provide.

  To achieve the above object, a digital broadcast receiver according to a first aspect of the invention receives a digital broadcast signal and performs an error correction process on a broadcast signal corresponding to a designated station; A digital broadcast receiver including a reproduction processing unit that performs reproduction processing based on the broadcast signal that has been subjected to error correction in a reception processing unit, and an error rate detection unit that detects an error rate in the error correction processing; Supply power reduction means for reducing power supplied to the reception processing section and the reproduction processing section when the error rate detected by the error rate detection means exceeds a preset reference value of the error rate. It is said.

In the first aspect of the invention, when a digital broadcast signal is received, an error correction process is performed on the broadcast signal corresponding to the designated station in the reception processing unit, and then a reproduction process is performed in the reproduction processing unit. .
At this time, the error rate detection means detects the error rate in the error correction process, and when the detected error rate exceeds a preset reference value of the error rate, the supplied power reduction means causes the reception processing unit and the reproduction processing unit to Power supply is reduced.

  Therefore, when the error rate exceeds the reference value and a good reception state cannot be expected, the power consumption can be reduced by reducing the power supplied to the reception processing unit and the reproduction processing unit. On the contrary, when the error rate is below the reference value and a good reception state can be expected, the digital broadcast signal can be reproduced well by sufficiently supplying power to the reception processing unit and the reproduction processing unit. be able to.

In the second invention, the reception processing unit performs Reed-Solomon decoding on the broadcast signal as the error correction processing, and the error rate detection means detects an error rate after the Reed-Solomon decoding, The error rate reference value is set based on 1 × 10 ⁻¹¹ .
In the second invention, the reception processing unit performs Reed-Solomon decoding as error correction processing, and the error rate detection means detects the error rate after Reed-Solomon decoding.

Here, when the error rate after Reed-Solomon decoding is 1 × 10 ⁻¹¹ or less, it is known that there is substantially no error, so-called pseudo error free. By setting a reference value based on the error rate after Reed-Solomon decoding and making a determination based on the error rate after Reed-Solomon decoding, it is possible to accurately determine whether to start or cancel the reduction in power supply. It can be carried out.

In the third aspect of the invention, the reception processing unit performs Viterbi decoding and Reed-Solomon decoding on the broadcast signal in this order as the error correction processing, and the error rate detection means calculates the error rate after the Viterbi decoding. And the reference value of the error rate is set based on 2 × 10 ⁻⁴ .
In the third invention, the reception processing unit performs Viterbi decoding and then Reed-Solomon decoding as error correction processing, and the error rate detection means detects the error rate after Viterbi decoding.

Here, it is known that when the error rate after Reed-Solomon decoding is 1 × 10 ⁻¹¹ or less, there is substantially no error, so-called pseudo error free, and errors after Viterbi decoding If the rate is 2 × 10 ⁻⁴ or less, it is known that the error rate after Reed-Solomon decoding is 1 × 10 ⁻¹¹ or less. By setting a reference value based on the error rate and making a determination based on the error rate after Viterbi decoding, it is possible to accurately determine whether to start or cancel the reduction in power supply.

According to a fourth aspect of the present invention, the supply power reduction means includes an intermittent supply means for intermittently supplying power to the reception processing section, and a power supply cutoff means for cutting off power supply to the regeneration processing section, It is characterized by having.
In the fourth aspect of the invention, the supply power reduction means intermittently supplies power to the reception processing section by the intermittent supply means, and supplies power to the reproduction processing section by the power supply cutoff means. Shut off.

  Here, when the error rate exceeds the reference value, that is, the reception state is not good, in this state, the power supply to the reproduction processing unit is cut off and the reproduction processing unit is stopped. There is no problem. On the other hand, the reception processing unit is intermittently supplied with power, receives digital broadcast signals at predetermined intervals, detects an error rate for this, and monitors the recovery state of the reception state. Therefore, it is possible to effectively reduce the supply power and to quickly return the supply power to the recovery of the reception state.

  According to a fifth aspect of the present invention, the reproduction processing unit has reproduction display means operable to reproduce and display an image and operate in a power reduction mode that operates with less power consumption than normal, and receives from the reception processing unit. An image reproduction signal for reproduction display in the reproduction display unit is generated based on the signal, and the supply power reduction unit includes an intermittent supply unit that intermittently supplies power to the reception processing unit, and the reproduction display unit Power supply shut-off means for shutting off power supply to the reproduction processing unit except for, and an operation mode switching means for instructing the reproduction display means to operate in the power reduction mode, the reproduction display means, When an operation in the power reduction mode is instructed by the operation mode switching means, a preset playback image for power reduction is reproduced and displayed.

  In the fifth invention, the reproduction processing unit has reproduction display means for reproducing and displaying an image, and the reproduction display means is configured to be operable in a power reduction mode that operates with less power consumption than usual. ing. The supply power reduction means intermittently supplies power to the reception processing section by the intermittent supply means, and to the reproduction processing section excluding the reproduction display means, the power supply cutoff means performs power supply. Shut off the supply. Further, the reproduction display means is instructed to operate in the power reduction mode by the operation mode switching means.

Here, since the error rate exceeds the reference value, that is, the reception state is not good, in this state, the power supply to the reproduction processing unit excluding the reproduction display unit is shut off, There is no problem even if it is stopped.
On the other hand, the reception processing unit is intermittently supplied with power, receives digital broadcast signals at predetermined intervals, detects an error rate for this, and monitors the recovery state of the reception state. Therefore, it is possible to effectively reduce the supply power and to quickly return the supply power to the recovery of the reception state. At this time, power is not supplied to the playback processing unit, but power is supplied to the playback display means, and the playback display means operates in a power reduction mode with lower power consumption than normal. In this case, the reproduction display means reproduces and displays a preset power-reduction reproduction image.

Here, if the reproduction display means is stopped when the error rate exceeds a reference value, the display image on the reproduction display means disappears suddenly, giving the user a sense of incongruity. In addition, since the power-removed mode playback image is displayed while operating in the power reduction mode, it is possible to reduce power without causing the user to feel uncomfortable.
According to a sixth aspect of the invention, there is provided pause time setting means for setting a pause time in the intermittent supply means based on a difference between the error rate detected by the error rate detection means and a reference value of the error rate. The pause time setting means sets the pause time so that the pause time becomes shorter as the difference between the error rate and the reference value is smaller.

In the sixth aspect of the invention, the pause time in the intermittent supply means is set by the pause time setting means based on the difference between the error rate detected by the error rate detection means and the reference value of the error rate.
Here, since the pause time setting means sets the pause time to be shorter as the difference between the error rate and its reference value is smaller, the error rate greatly exceeds the reference value, and rapid recovery cannot be expected. If the error rate is not much higher than the reference value and is expected to recover relatively quickly, the pause time is reduced. By shortening and monitoring the error rate frequently, i.e., monitoring the reception status, it is possible to respond quickly to the temporary deterioration of the error rate, cancel the power reduction, and perform normal reception operation. It can be carried out.

According to a seventh aspect of the invention, there is provided an electric field strength detecting means for detecting an electric field strength of the received digital broadcast signal, and a pause time in the intermittent supply means is set based on the electric field strength detected by the electric field strength detecting means. The pause time setting means is configured to set the pause time so that the pause time becomes shorter as the electric field strength is larger.
In the seventh aspect of the invention, the electric field strength of the received digital broadcast is detected by the electric field strength detection means, and based on the electric field strength detected by the electric field strength detection means, the pause time setting means pauses the intermittent supply means. Time is set.

  Here, since the pause time setting means sets the pause time to be shorter as the electric field strength is larger, the electric field strength is larger, and the cause of the deterioration of the error rate is not due to the lowering of the electric field strength. For example, if it is predicted to be caused by a relatively transient factor such as multipath interference or intermodulation interference, the pause time is shortened and the error rate is monitored, that is, the reception state is frequently monitored. As a result, it is possible to quickly cope with the recovery from the deterioration of the error rate due to the temporary factor, cancel the power reduction, and perform the normal reception operation. Conversely, when it is predicted that the electric field strength is low and the error rate deterioration is not due to a transient factor and a rapid recovery cannot be expected, it is effective to increase the pause time. In addition, power can be reduced.

Embodiments of the present invention will be described below.
First, a first embodiment will be described.
FIG. 1 is an external view showing an example of a television receiver for receiving terrestrial digital broadcasting to which the present invention is applied, wherein (a) is a plan view, (b) is a left side view, and (c) is a right side. FIG.
In FIG. 1, a television receiver 1 includes a vertically long receiving device main body 2 and a rod antenna 3.

When the rod antenna 3 is carried, the rod antenna 3 is housed in the left side surface portion 21 of the apparatus main body 2, and by rotating the rod antenna 3 180 degrees at the base end portion, as shown by a dotted line in FIG. It can be pulled out from the apparatus main body 2 upward.
The display unit 41 of the liquid crystal device 4 is disposed on the upper surface portion 22 of the apparatus main body 2 so that the received television image can be viewed. A channel selection channel button 12 or the like is disposed below the display unit 41, and a speaker 13 is disposed below the channel button 12.

Further, a brightness adjustment switch 14, an AV input unit 15, a power switch 16, and a backlight lighting switch 17 for the liquid crystal device 4 are disposed on the right side surface portion 23 of the apparatus main body 2.
FIG. 2 is a configuration diagram illustrating a schematic configuration of the television receiver 1.
The received broadcast signal received by the rod antenna 3 is input to the channel selection unit 101, and the channel selection unit 101 extracts a broadcast signal corresponding to a desired channel. The extracted broadcast signal is converted into a digital signal of “0” or “1” by the OFDM demodulator 102.

  The digital broadcast signal converted by the OFDM demodulator 102 is subjected to error correction processing by a known procedure in the error correction unit 103, and then restored to a TS packet generated by the broadcast station. In the error correction process, assuming that a TS packet is transmitted with Reed-Solomon encoding and convolutional encoding, for example, at a broadcasting station, Viterbi decoding and RS (Reed-Solomon) decoding are performed to restore the TS packet. .

The restored TS packet is input to the MPEG demodulator 104, where it is decoded into a video signal and an audio signal, and output to the speaker 13 and the liquid crystal device 4 to reproduce the audio and image.
The television receiver 1 further includes a supply power control unit 120 that controls the power supplied from the power supply 110 to each unit based on the error correction result in the error correction unit 103.

  The power supply control unit 120 includes an error rate detection unit 121 that detects an error rate (BER) in the error correction unit 103, an error rate S detected by the error rate detection unit 121, and a preset error rate reference A comparator 122 for comparing the value Sth; a cutoff circuit 123 inserted from the power supply 110 to the MPEG demodulator 104, the speaker 13 and the liquid crystal device 4; and the channel selector 101 from the power supply 110, It comprises an OFDM demodulator 102 and an operation mode switching circuit 124 inserted in the power supply line to the error correction unit 103.

The operation mode switching circuit 124 is either a continuous operation mode in which power is continuously supplied to the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103, or an intermittent operation mode in which the power supply is intermittently performed. It operates in such an operation mode, and includes, for example, a cutoff circuit and a timer.
In the case of the continuous operation mode, the interruption circuit is switched to a conduction state, and in the case of the intermittent operation mode, the operation is performed according to the count value of the timer, and the interruption circuit is made conductive for a predetermined conduction time. After controlling to the state, the interruption circuit is controlled to be in the interruption state for a predetermined interruption time, and by repeating these operations, an intermittent operation is performed in which power is supplied for the conduction time with a pause time.

The comparator 122 outputs a binary signal according to whether or not the error rate S detected by the error rate detector 121 is equal to or less than the error rate reference value Sth. The cutoff circuit 123 and the operation mode switching circuit 124 operate according to the binary signal.
That is, when the error rate S of the comparator 122 is equal to or less than the reference value Sth, the cutoff circuit 123 is in a conductive state, and the operation mode switching circuit 124 operates in the continuous operation mode. That is, the power supply to each part constituting the television receiver 1 is continued, and the television receiver 1 is controlled to a state in which the television receiver 1 can be normally operated.

On the contrary, when the error rate S exceeds the reference value Sth, the cutoff circuit 123 enters the cutoff state, and the operation mode switching circuit 124 operates in the intermittent operation mode. That is, the power supply to the MPEG demodulation unit 104, the speaker 13, and the liquid crystal device 4 is cut off, and the power supply to the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103 is intermittently performed.
Here, the reference value Sth of the error rate is set to a value at which it can be determined that the reception state is good. Specifically, the error rate reference value Sth is set to 1 × 10 ⁻¹¹ that can be regarded as pseudo error free, for example, as an error rate after RS decoding in the error correction unit 103.

That is, the error rate S detected by the error rate detection unit 121 is equal to or less than the error rate reference value Sth, the error rate of the digital broadcast signal is small, and the video signal and the audio signal are decoded based on the digital broadcast signal. In the case where it can be considered that a good image and sound can be obtained, power is supplied to each unit, and a broadcast signal is always received and reproduced.
On the other hand, when the error rate S detected by the error rate detection unit 121 exceeds the error rate reference value Sth, the error rate of the digital broadcast signal is large, and a video signal or an audio signal is decoded based on the digital broadcast signal. When it is determined that it is difficult to obtain a good image and sound, the power supplied to the MPEG demodulator 104, the speaker 13, and the liquid crystal device 4 is cut off. By stopping decoding, power consumption is reduced.

In addition, power is supplied to the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103. However, by intermittently supplying power and monitoring whether the reception state has been intermittently recovered, power consumption can be reduced. In addition to the reduction, the recovery status of the reception state is promptly detected.
The cut-off circuit 123 and the operation mode switching circuit 124 are in an initial state, that is, when the power switch 16 is turned on, the cut-off circuit 123 is in a conductive state, and the operation mode switch circuit 124 is in a continuous operation mode. Thus, power is supplied to each part of the television receiver 1.

Next, the operation of the first embodiment will be described.
When the power switch 16 is switched to the ON state, power is supplied from the power supply 110 to each unit, and each unit is ready for operation.
Then, the broadcast signal transmitted from the broadcast station is input to the channel selection unit 101, and the broadcast signal corresponding to the channel selected here is extracted, and this is converted into a digital broadcast signal by the OFDM demodulation unit 102. This digital broadcast signal is subjected to error correction processing in the error correction unit 103, Viterbi decoding and RS decoding are performed, and the TS packet is restored. Then, the MPEG demodulation unit 104 decodes the digital broadcast signal into a video signal and an audio signal. These signals are output to the speaker 13 and the liquid crystal device 4 to reproduce sound and images.

  If the reception state is good, the error rate S detected by the error rate detection unit 121 in the error correction unit 103 is equal to or less than the reference value Sth. Accordingly, the cutoff circuit 123 is turned on in accordance with the output of the comparator 122, and the operation mode switching circuit 124 operates in the continuous operation mode. Therefore, the power supply to each unit is continuously performed, and the broadcast signal is reproduced in a good reception state.

From this state, for example, due to a decrease in the electric field level, multipath interference, image frequency interference, cross modulation interference, etc., the reception status of the radio wave at the rod antenna 3 deteriorates, and the error detected by the error rate detection unit 121 When the rate S exceeds the reference value Sth, the cutoff circuit 123 is switched to the cutoff state, and the operation mode switching circuit 124 is switched to the intermittent operation mode.
As a result, the power supplied to the MPEG demodulator 104, the speaker 13, and the liquid crystal device 4 is cut off, and the reproduction of the broadcast signal is stopped. However, in this case, the error rate S exceeds the reference value Sth, the reception state is deteriorated, and a good image cannot be obtained even if it is reproduced.

Therefore, there is no problem even if the power supply to the MPEG demodulator 104, the speaker 13, and the liquid crystal device 4 is stopped. Therefore, when the reception state is not good, the power consumption can be reduced correspondingly by stopping the MPEG demodulation unit 104, the speaker 13, and the liquid crystal device 4.
On the other hand, by setting the operation mode switching circuit 124 to the intermittent operation mode, power supply to the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103 is intermittently performed.

Then, during a period in which power is supplied, that is, a period in which the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103 are operable, a broadcast signal corresponding to a designated channel is extracted from the received broadcast signal. In response to this, the error correction unit 103 performs error correction processing.
At this time, when the error rate S exceeds the reference value Sth, the cutoff circuit 123 is continuously maintained in the cutoff state and the operation mode switching circuit 124 is maintained in the intermittent operation mode. That is, while the reception state is poor, the power supply to the MPEG demodulation unit 104, the speaker 13, and the liquid crystal device 4 is cut off to reduce power consumption, and the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit. The power supply to 103 is intermittently performed to reduce power consumption, and the reception state is periodically monitored.

From this state, when the reception state is recovered and the error rate S becomes equal to or less than the reference value Sth, the cutoff circuit 123 becomes conductive, and the operation mode switching circuit 124 operates in the continuous operation mode.
As a result, processing in the MPEG demodulator 104 is started, and a video signal and an audio signal are restored from the TS packet, which are output to the speaker 13 and the liquid crystal device 4, and reproduction is resumed.

Further, since the operation mode switching circuit 124 operates in the continuous operation mode, power is continuously supplied to the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103, thereby reproducing the broadcast signal. Will be performed continuously.
Thereafter, while the reception state is good and the error rate S is equal to or less than the reference value Sth, the broadcast signal is continuously reproduced.

When the error rate S again exceeds the reference value Sth, the power supply to the MPEG demodulation unit 104, the speaker 13, and the liquid crystal device 4 is cut off, and the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103 In the intermittent operation mode, the power consumption is reduced.
As described above, since the power consumption is reduced when the error rate S exceeds the reference value Sth, the power consumption can be reduced when it is estimated that reproduction cannot be performed satisfactorily. The power consumption can be reduced at an appropriate timing.

  At this time, as a determination condition for switching to the intermittent operation mode, the determination is made based on the error rate S in the error correction unit 103. Here, the error rate appears as a result of taking into account not only the electric field strength but also all conditions such as multipath interference, image frequency interference, and cross modulation interference, so that the reception state is represented most accurately and quantitatively. . Therefore, since the switching to the intermittent operation mode is performed based on the error rate, the switching can be performed at the most appropriate timing according to the reception state.

Further, as shown by the broken line in FIG. 3, in the case of analog television broadcasting, as the radio wave condition deteriorates, screen noise gradually increases or ghosts become conspicuous, and the received image quality gradually increases. Even if the radio wave condition further deteriorates, it can be received to the extent that the contents can be understood.
On the other hand, in the case of digital television broadcasting, as shown by the solid line in FIG. 3, even if the radio wave condition is somewhat worse, as long as the data is correctly demodulated by error correction processing, Can not display clean images. However, if the radio wave condition deteriorates to the extent that data cannot be demodulated correctly even after error correction, an image cannot be displayed at all. By switching between the continuous operation mode and the intermittent operation mode using such a nature of digital television broadcasting, so-called cliff effect, power consumption can be reduced at an accurate timing, which is extremely effective.

In FIG. 3, the horizontal axis represents the electric field intensity of the received radio wave, and the electric field intensity is weaker toward the right side in FIG. The vertical axis represents the received image quality, and the higher the image is in FIG. 3, the better the image quality is.
Next, a second embodiment of the present invention will be described.
Since the second embodiment is the same as the first embodiment except that the configuration of the supply power control unit is different, the same parts are denoted by the same reference numerals, and detailed description thereof is omitted. To do.

  As shown in FIG. 4, the supply power control unit 120a in the second embodiment is detected by the error rate detection unit 121 that detects the error rate in the error correction unit 103 and the error rate detection unit 121. The comparator 122 that compares the error rate S with the reference value Sth, the cutoff circuit 123a that cuts off the power supply from the power source 110 to the MPEG demodulator 104 and the speaker 13, the channel selection unit 101, the OFDM demodulator 102, and the error An operation mode switching circuit 124 for switching an operation mode for supplying power to the correction unit 103, a screen brightness changeover switch 126 for switching the screen brightness of the liquid crystal device 4, and a predetermined image. Image memory 127.

  The liquid crystal device 4 has a function of switching the screen brightness in accordance with the screen brightness switch 126. For example, when the backlight fluorescent tube is duty-driven and normal driving is instructed by the screen luminance changeover switch 126, the backlight fluorescent tube operates to have normal luminance. For example, the backlight fluorescent tube has a duty ratio of 100%. Drive. Conversely, when low-luminance driving is instructed by the screen luminance changeover switch 126, the screen luminance operates to be lower than usual. For example, the backlight fluorescent tube is turned on with a duty ratio of 50%. Duty drive.

  Further, when the low-luminance driving is instructed by the screen luminance changeover switch 126, the liquid crystal device 4 reads out and displays the image information at the time of low-luminance driving stored in the image memory 127 in advance. To do. The image information at the time of low-luminance driving is, for example, a message such as “The current radio wave condition is bad and cannot be received.” It is composed of information that can be notified.

  Then, the comparator 122 compares the error rate S detected by the error rate detection unit 121 with the reference value Sth, as in the first embodiment, and the error rate S is equal to or less than the reference value Sth. In response to the binary signal, the cut-off circuit 123a is switched to either a cut-off state or a conductive state, and the operation mode switching circuit 124 is output. Switches the operation mode according to the binary signal.

Further, the screen luminance changeover switch 126 also operates in accordance with the output signal of the comparator 122. When the error rate S is less than the reference value Sth, the normal luminance drive is instructed, and conversely, the error rate. When S exceeds the reference value Sth, the low luminance driving is instructed.
When the power switch 16 is turned on, the cut-off circuit 123a is set in a conducting state, the operation mode switching circuit 124 is set in a continuous operation mode, and the screen luminance changeover switch 126 is set in a normal luminance drive.

Next, the operation of the second embodiment will be described.
If the error rate S is less than or equal to the reference value Sth, power is supplied to each part of the television receiver 1 and the screen brightness of the liquid crystal device 4 is controlled to be normal brightness. Therefore, the television receiver 1 operates normally, and the video signal and the audio signal are reproduced based on the received broadcast signal, and the reproduction with a good screen luminance is performed.

On the other hand, when the error rate S exceeds the reference value Sth, the cutoff circuit 123a is switched to the cutoff state, the operation mode switching circuit 124 is switched to the intermittent operation mode, and the screen luminance switching switch 126 is switched to low luminance driving.
For this reason, the power supplied to the MPEG demodulator 104 and the speaker 13 is cut off, and the screen luminance changeover switch 126 is switched to low luminance driving.

For this reason, the liquid crystal device 4 controls the duty driving ratio of the backlight fluorescent tube to perform low-luminance driving, and from the image memory 123, predetermined image information such as message information for notifying the radio wave state of failure. Is displayed on the display unit 41.
For this reason, since the message information for notifying that the reception state is bad is displayed on the liquid crystal device 4, the user can refer to this message so that the radio wave state is bad and normal. It can be recognized that no video is displayed.

  Therefore, even if a normal image is not displayed on the liquid crystal device 4, the user does not feel uncomfortable. Also, at this time, the image brightness is driven at a low brightness. Thus, when displaying message information, the user looks at the display screen and obtains information or enjoys the contents. Therefore, there is no problem even if the image brightness is lowered. By reducing the image luminance in this way, it is effective because power consumption can be reduced accordingly.

On the other hand, since the operation mode switching circuit 124 operates in the intermittent operation mode and intermittently drives the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103, power consumption can be reduced by reducing the drive time of each unit. Reduction can be achieved.
Therefore, in this case as well, it is possible to obtain the same operational effects as the first embodiment, and avoid giving the user a sense of incongruity due to the operation for reducing power consumption. it can.

Here, the case where the predetermined image information stored in the image memory 127 is displayed when the image brightness is lowered has been described. However, the present invention is not limited to this. When the switch 126 is switched to the low luminance drive, the image information input immediately before the switch 126 may be held, and this image information may be continuously displayed. In short, any screen may be displayed as long as the user can recognize that the reception state is poor. In this case, the screen brightness may be low.
Next, a third embodiment of the present invention will be described.
Since the third embodiment is the same as the first embodiment except that the configuration of the power supply control unit 120 is different, the same reference numerals are given to the same parts, and detailed descriptions thereof are omitted. To do.

  As shown in FIG. 5, the power supply control unit 120b in the third embodiment includes an error rate detection unit 121 that detects an error rate in the error correction unit 103, and an error detected by the error rate detection unit 121. A comparator 122a that compares the rate S with its reference value Sth and outputs a binary signal according to the comparison result and a signal representing the difference ΔS between the error rate S and its reference value Sth; Power supply to the pause time control unit 128 for setting the pause period in the intermittent operation mode of the operation mode switching circuit 124a based on the comparison result in the device 122a, the MPEG demodulator 104, the speaker 13, and the liquid crystal device 4. The interruption circuit 123 operates in response to a signal representing the comparison result from the comparator 122a as in the first embodiment, and the error rate S is It is controlled to a cutoff state when above the reference value Sth.

  The operation mode switching circuit 124a operates in one of the continuous operation mode and the intermittent operation mode similarly to the operation mode switching circuit 124 in each of the above embodiments. In the intermittent operation mode, the pause time control is performed. During the pause time set by the unit 128, power supply to the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103 is paused.

  The pause time control unit 128 receives a signal indicating whether or not the error rate S is less than or equal to a reference value Sth from the comparator 122a, and when the error rate S is less than or equal to a reference value Sth, the operation is performed. When the continuous operation mode is instructed to the mode switching circuit 124a, and conversely, when the error rate S exceeds the reference value Sth, based on the difference ΔS between the error rate S from the comparator 122a and the reference value Sth. The pause time is set.

For example, the pause time is set shorter as the difference ΔS is smaller. This is because the correspondence between the difference ΔS between the error rate S and the reference value Sth and the pause time is set in advance, and the pause time corresponding to the detected difference ΔS may be searched. A functional expression representing the relationship between ΔS and the downtime may be set and set based on this.
That is, in the third embodiment, when the reception state is good, the error rate S is equal to or less than the reference value Sth, so that the cutoff circuit 123 is in a conductive state and the operation mode switching circuit 124a is continuous. The operation mode is set. For this reason, power supply to each unit is continuously performed, and normal reproduction is performed.

Then, when the reception state deteriorates and the error rate S increases and exceeds the reference value Sth, the cutoff circuit 123 switches to the cutoff state. The pause time control unit 128 sets the operation mode switching circuit 124a to the intermittent operation mode, and further sets a pause time corresponding to the difference ΔS between the error rate S and the reference value Sth.
For example, even when the error rate S exceeds the reference value Sth, if the difference ΔS between the error rate S and the reference value Sth is small and the error rate S does not exceed the reference value Sth so much, the radio wave The situation is not getting worse, and it can be predicted that it may recover relatively quickly. Therefore, the pause time is set short. In other words, in preparation for an early recovery of the error rate, data reception is avoided as much as possible by monitoring the reception status in a short cycle.

  On the other hand, when the difference ΔS between the error rate S and the reference value Sth is large and the error rate S is much higher than the reference value Sth, the radio wave condition has deteriorated and the time has passed or the location has moved. Regardless, it can be assumed that there is little possibility of recovery, so the pause time is set longer. That is, assuming that an early recovery of the error rate cannot be expected, a sufficient pause time is set to reduce power consumption.

As described above, in the third embodiment, the power consumption is reduced in consideration of the difference ΔS between the error rate S and the reference value Sth, that is, the degree of the error rate S. The operational effects equivalent to those of the embodiment can be obtained, and data can be avoided as much as possible, and the power consumption can be more efficiently reduced.
In the third embodiment, the case where the present invention is applied to the first embodiment has been described. However, the present invention is not limited to this, and can be applied to the second embodiment.

Next, a fourth embodiment of the present invention will be described.
Since the fourth embodiment is the same as the third embodiment except that the configuration of the power supply control unit 120b is different, the same parts are denoted by the same reference numerals and detailed description thereof is omitted. To do.
As shown in FIG. 6, the supply power control unit 120c according to the third embodiment further includes a broadcast signal corresponding to a desired channel extracted by the channel selection unit 101 in the supply power control unit 120b shown in FIG. An electric field strength detector 129 for detecting the electric field strength is provided. The pause time control unit 128 sets a pause period in the intermittent operation mode of the operation mode switching circuit 124a based on the electric field strength detected by the electric field strength detector 129.

  That is, the pause time control unit 128 receives a signal indicating whether the error rate S is less than or equal to the reference value Sth from the comparator 122, and when the error rate S is less than or equal to the reference value Sth. The operation mode switching circuit 124a is instructed to operate continuously. Conversely, when the error rate S exceeds the reference value Sth, the intermittent operation mode is instructed, and the pause time is set based on the electric field strength detected by the electric field strength detector 129.

For example, the pause time control unit 128 sets the pause time shorter as the electric field strength increases. In this case, the correspondence between the electric field strength and the pause time may be set in advance, and the pause time corresponding to the detected electric field strength may be searched. Also, a functional expression representing the relationship between the electric field strength and the pause time. May be set and set based on this.
That is, in the fourth embodiment, when the reception state is good, the error rate S is equal to or less than the reference value Sth, so that the cutoff circuit 123 is in a conductive state and the operation mode switching circuit 124a is continuous. The operation mode is set. For this reason, power supply to each unit is continuously performed, and normal reproduction is performed.

When the reception state deteriorates and the error rate S increases and exceeds the reference value Sth, the cutoff circuit 123 switches to the cutoff state, and the pause time control unit 128 intermittently switches the operation mode switching circuit 124a. Set the operation mode. Further, the pause time control unit 128 sets a pause time according to the electric field strength detected by the electric field strength detector 129.
For example, even when the error rate exceeds the reference value Sth, if the electric field strength is large, it can be considered that the error rate has increased due to multipath interference, image frequency interference, or the like. Therefore, since it can be predicted that there is a possibility of recovery relatively quickly with the passage of time or the movement of the place, the pause time is set short. In other words, in preparation for an early recovery of the error rate, data reception is avoided as much as possible by monitoring the reception status in a short cycle.

On the other hand, when the electric field strength is small, the increase in error rate is due to the electric field strength, and it can be considered that there is little possibility of recovery regardless of the passage of time or movement of place. Set the pause time longer. That is, assuming that an early recovery of the error rate cannot be expected, a sufficient pause time is set to reduce power consumption.
As described above, in the fourth embodiment, power consumption is reduced in consideration of not only the error rate but also the electric field strength. In this case as well, this is equivalent to the first embodiment. In addition to obtaining operational effects, it is possible to avoid missing data as much as possible and to reduce power consumption more efficiently.

In the fourth embodiment, the case where the present invention is applied to the first embodiment has been described. However, the present invention is not limited to this, and can be applied to the second embodiment. Further, in combination with the third embodiment, the pause time may be set in consideration of not only the electric field strength but also the difference ΔS between the error rate S and the reference value Sth.
In each of the above embodiments, as described above, low power consumption can be achieved. Therefore, the present invention is particularly effective when applied to a portable or mobile television receiver. However, the present invention is not limited to this, and needless to say, the present invention can also be applied to a fixed television receiver.

In each of the above embodiments, the error rate reference value Sth is set to 1 × 10 ⁻¹¹ that can be regarded as pseudo error free as the error rate after RS decoding in the error correction unit 103. However, the present invention is not limited to this, and the error rate after Viterbi decoding may be set to 2 × 10 ⁻⁴ .
In addition, the value is not limited to a value that can be regarded as pseudo error free, and can be set arbitrarily. However, as described above, if the reference value Sth is set to a value that can be regarded as pseudo-error free, whether or not it is in a pseudo-error free state, that is, a good reception state. Therefore, by setting a value that is pseudo error free as the reference value Sth, it is possible to accurately detect whether the reception state is good.

  Moreover, although the case where the RS decoding and the Viterbi decoding are performed as the error processing in the error correction unit 103 has been described, only one of them may be performed, and the present invention is not limited to this. The present invention can be applied even when error correction processing is performed. In this case, as the reference value Sth of the error rate, a value that can be regarded as a good reception state may be set based on the error rate at the time of each error correction process.

  In each of the above embodiments, the case where the present invention is applied to the television receiver 1 that receives a terrestrial digital broadcast signal has been described. However, the present invention is not limited to this. For example, an image together with a digital radio broadcast or a digital radio broadcast signal is displayed. A receiver that can receive a signal or the like as a digital signal can also be applied. In short, a receiver that receives a digital signal and performs an error correction process on the digital signal. If so, it can be applied.

  In the above embodiment, the channel selection unit 101, the OFDM demodulation unit 102, and the error correction unit 103 correspond to the reception processing unit, the MPEG demodulation unit 104, the speaker 13, and the liquid crystal device 4 correspond to the reproduction processing unit, and the error rate. The detection unit 121 corresponds to the error rate detection means, the comparator 122, the cutoff circuits 123 and 123a, and the operation mode switching circuit 124 correspond to the supply power reduction means, the operation mode switching circuit 124 corresponds to the intermittent supply means, and the cutoff. The circuits 123 and 123a correspond to the power supply cutoff means, the liquid crystal device 4 corresponds to the reproduction display means, the screen luminance changeover switch 126 corresponds to the operation mode switching means, and the pause time control unit 128 corresponds to the pause time setting means. The electric field strength detector 129 corresponds to the electric field strength detection means.

It is an external view which shows an example of the television receiver to which this invention is applied. It is a block diagram which shows an example of the television receiver in 1st Embodiment. It is a characteristic view showing the correspondence between electric field strength and received image quality in digital television broadcasting and analog television broadcasting. It is a block diagram which shows an example of the television receiver in 2nd Embodiment. It is a block diagram which shows an example of the television receiver in 3rd Embodiment. It is a block diagram which shows an example of the television receiver in 4th Embodiment.

Explanation of symbols

  4 Liquid Crystal Device 13 Speaker 101 Channel Selection Unit 102 OFDM Demodulation Unit 103 Error Correction Unit 104 MPEG Demodulation Unit 121 Error Rate Detection Unit

Claims (7)

A reception processing unit that receives a digital broadcast signal and performs error correction processing on the broadcast signal corresponding to the designated station, and reproduction that performs reproduction processing based on the broadcast signal that has been subjected to error correction by the reception processing unit A digital broadcast receiver comprising a processing unit,
Error rate detection means for detecting an error rate in the error correction processing;
When the error rate detected by the error rate detection means exceeds a preset reference value of the error rate, supply power reduction means for reducing the supply power to the reception processing unit and the reproduction processing unit;
A digital broadcast receiver comprising: The reception processing unit performs Reed-Solomon decoding on the broadcast signal as the error correction processing,
The error rate detection means detects an error rate after the Reed-Solomon decoding,
The digital broadcast receiver according to claim 1, wherein the reference value of the error rate is set based on 1 × 10 ⁻¹¹ . The reception processing unit performs Viterbi decoding and Reed-Solomon decoding in this order on the broadcast signal as the error correction processing,
The error rate detection means detects an error rate after the Viterbi decoding,
The digital broadcast receiver according to claim 1, wherein the reference value of the error rate is set based on 2 × 10 ⁻⁴ .   The supply power reduction means includes: intermittent supply means for intermittently supplying power to the reception processing section; and power supply cutoff means for cutting off power supply to the reproduction processing section. Item 4. The digital broadcast receiver according to any one of Items 1 to 3. The reproduction processing unit includes a reproduction display unit that reproduces and displays an image and can operate in a power reduction mode that operates with less power consumption than usual, and the reproduction display unit based on a reception signal from the reception processing unit Generate an image playback signal for playback display in
The supply power reduction means includes intermittent supply means for intermittently supplying power to the reception processing section, power supply cutoff means for cutting off power supply to the reproduction processing section excluding the reproduction display means, and the reproduction Operation mode switching means for instructing the display means to operate in the power reduction mode,
The reproduction display means is configured to reproduce and display a preset reproduction image for power reduction when an operation in the power reduction mode is instructed by the operation mode switching means. Item 4. The digital broadcast receiver according to any one of Items 1 to 3. A pause time setting means for setting a pause time in the intermittent supply means based on a difference between the error rate detected by the error rate detection means and a reference value of the error rate;
5. The pause time setting means sets the pause time so that the pause time becomes shorter as the difference between the error rate and the reference value is smaller. 5. The digital broadcast receiver according to 5. Electric field strength detecting means for detecting the electric field strength of the received digital broadcast signal;
Based on the electric field strength detected by the electric field strength detection means, comprising a pause time setting means for setting a pause time in the intermittent supply means,
6. The digital broadcasting receiver according to claim 4, wherein the pause time setting means sets the pause time so that the pause time becomes shorter as the electric field strength is larger. .

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