JP2014165698A - Broadcast receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a "broadcast receiver" capable of minimizing a delay in return from information reproduction using a strong hierarchy broadcast signal to information reproduction using a weak hierarchy broadcast signal.SOLUTION: The present invention has: reproduction mode switching means for switching, when reception quality has dropped to a switching quality level, from a first reproduction mode in which a weak hierarchy first broadcast signal is used for information reproduction to a second reproduction mode in which a strong hierarchy second broadcast signal is used for information reproduction, and having, when the reception quality is continually in a state exceeding a return quality level for a certain time, the reproduction mode returned to the first reproduction mode; and background processing means for executing, while information reproduction is underway in the second reproduction mode, a background process by using remaining one or more receiving units except for information reproduction among a prescribed number of receiving units, the present invention being configured so that a return quality level for the case where the background process is executed is set lower than for the case where the background process is not executed.

Description

  The present invention relates to a broadcast receiving apparatus that performs background processing such as channel search while receiving weak-layer broadcast signals and strong-layer broadcast signals that are digitally broadcast by hierarchical transmission, such as terrestrial digital broadcasting.

  In terrestrial digital broadcasting currently being performed, hierarchical transmission in which the modulation method of carrier waves and the strength of error correction can be changed for each segment in one channel is performed. With this hierarchical transmission, for example, among 13 segments (segment: basic unit of frequency bandwidth) included in one channel, a broadcast signal such as a high-definition high-definition broadcast signal using 12 segments and a high information rate, A broadcast signal including a broadcast signal modulated by a method resistant to fluctuations in radio waves using the remaining one segment is provided for broadcasting. In hierarchical transmission, a high-quality broadcast signal with a high information rate that is broadcast using 12 segments is a weak-layer broadcast signal that is vulnerable to radio wave fluctuations. On the other hand, a broadcast signal modulated using a method resistant to fluctuations of the radio wave broadcast using one segment, that is, a broadcast signal in a strong hierarchy, has a low information rate and a low quality.

  As a vehicle-mounted receiving device that receives a broadcast signal used for broadcasting by hierarchical transmission as described above, a device described in Patent Document 1 is known. In this in-vehicle receiving apparatus, since the reception quality of the broadcast signal varies variously while the vehicle is traveling, reproduction of information (broadcast program audio and video) using the broadcast signal of the weak hierarchy according to the reception quality. (Video display and sound output) and reproduction of information using the broadcast signal of the higher hierarchy are switched. That is, when the reception quality is good, high-quality information (sound, high-definition video, etc.) is reproduced using the broadcast signal of the weak hierarchy (12-segment broadcasting), and when the reception quality is reduced, Information (audio, television video) is reproduced using the broadcast signal of the strong hierarchy (one-segment broadcasting).

  Moreover, in the vehicle-mounted receiving device described in Patent Document 1, broadcast signals received by four receiving units (antenna unit and channel selection / demodulation unit) are diversity-combined (four-diversity combining) to obtain a combined received signal. ing. Then, based on the reception quality parameter C (carrier power) / N (noise power) obtained from the combined received signal, the portion of the weak hierarchy broadcast signal (12-segment broadcast) included in the combined received signal and the strong hierarchy One of the parts of the broadcast signal (one-segment broadcasting) is used for information reproduction.

  Furthermore, in terrestrial digital broadcasting, broadcast programs having the same content as broadcast programs from each broadcast station are broadcast from relay stations on different channels. In addition, different broadcast stations (broadcast stations of the same series) may broadcast broadcast programs with the same content on different channels. In a conventional in-vehicle receiving device (see Patent Document 1) that can receive broadcast signals of various channels (broadcast stations, relay stations), the reception quality of the broadcast signals of the selected channels (broadcast stations) decreases. When it comes, it is used for diversity synthesis at a predetermined timing after switching from information reproduction using a broadcast signal of weak hierarchy (12-segment broadcast) to information reproduction using a broadcast signal of strong hierarchy (one-segment broadcast). Receiving (broadcasting program audio and video) reproduction (video display and audio) by receiving a broadcast signal of the selected channel at one or a plurality of receiving units out of four received units. In the background process, a channel search for a channel such as a relay station broadcasting the same broadcast program is performed using the remaining receiving units. Then, the broadcast signal related to the broadcast program of the new channel obtained by the channel search is received by the four receiving units and diversity-combined, and the broadcast signal of the weak hierarchy (12-segment broadcast) included in the combined received signal is received. ) Is reproduced (return to information reproduction of a broadcast signal (12-segment broadcasting) of a weak hierarchy).

JP 2011-87051 A

  By the way, in the in-vehicle receiving apparatus as described above, in consideration of moving in an unstable area of the broadcast radio wave environment, information reproduction using a weak hierarchy broadcast signal (12-segment broadcasting) and a strong hierarchy It is usually conceivable to switch the reproduction of information using a broadcast signal (one segment) with so-called hysteresis characteristics. For example, when the reception quality is equal to or lower than a predetermined threshold value, switching from reproducing information using a weak broadcast signal (12-segment broadcasting) to reproducing information using a strong broadcast signal (one-segment broadcasting), When the reception quality exceeds the threshold, the information is not immediately restored to the information reproduction using the broadcast signal of the weak layer (12-segment broadcasting), but the state where the reception quality exceeds the threshold is maintained for a certain period of time. When it is determined that the reception quality is in a stable state, the information is restored to the information reproduction using the broadcast signal (12-segment broadcasting) of the weak hierarchy. By switching with the hysteresis characteristic in this way, when moving in an unstable area of the broadcast radio wave environment where the reception quality becomes unstable, information reproduction and strong hierarchy using weak broadcast signals (12-segment broadcasting) It is possible to prevent a situation in which the reproduction of information using the broadcast signal (one segment) is frequently switched.

  However, during the reproduction of information using a strong hierarchy broadcast signal (one segment), as described above, a part of the reception unit (for example, two reception units) is used to perform the channel search or the like described above. When background processing is executed, the reception quality at the remaining reception units is in a state of being lower than the reception quality at all reception units (for example, four reception units). For this reason, even if the background processing is finished, the influence of the reception quality in the lowered state remains, and the return to the reproduction of information using the broadcast signal (12-segment broadcast) of the weak hierarchy according to the hysteresis characteristic remains. It will be late.

  The present invention has been made in view of such circumstances, and can reduce the delay in returning from the reproduction of information using a strong hierarchy broadcast signal to the reproduction of information using a weak hierarchy broadcast signal as much as possible. A broadcast receiving apparatus is provided.

  A broadcast receiving apparatus according to the present invention receives a broadcast signal including a first broadcast signal of a weak hierarchy and a second broadcast signal of a strong hierarchy, which is digitally broadcast by hierarchical transmission, at a reception unit having a predetermined number of reception units. A broadcast receiving apparatus that reproduces information based on either the first broadcast signal or the second broadcast signal received by the receiving unit, wherein the reception quality of the broadcast signal at the receiving unit is When the level is lowered to a predetermined switching quality level, the first reproduction form using the first broadcast signal for information reproduction is switched to the second reproduction form using the second broadcast signal for information reproduction, and the reception quality is predetermined. And a playback mode switching means for returning from the second playback mode to the first playback mode when the state exceeding the return quality level is continued for a certain period of time, and information is played back in the second playback mode. In a state A predetermined background process using one or a plurality of receiving units of the predetermined number of receiving units for receiving the broadcast signal related to the reproduction of the information, and using the remaining one or a plurality of receiving units. And a return condition adjustment for setting the return quality level when the background processing is performed by the background processing means to be lower than the return quality level when the background processing is not performed Means.

  With such a configuration, in the second reproduction mode in which information is reproduced using the second broadcast signal of the strong hierarchy, one or a plurality of reception units of a predetermined number of reception units are used for receiving the broadcast signal. On the other hand, when predetermined background processing is performed using the remaining one or a plurality of receiving units, the second reproduction form is changed to the first reproduction form in which information is reproduced using the first broadcast signal of the weak hierarchy. The return quality level, which is a condition for returning, is set lower than the return quality level when the background processing is not performed. In this case, one or a plurality of reception units of a predetermined number of reception units are used for background processing, and the reception quality of the broadcast signals by the remaining reception units is equal to that of the predetermined number of all reception units. Even if the reception quality is lower than the reception quality, the return from the second reproduction form to the first reproduction form is determined based on the reduced return reception quality level.

  A broadcast receiving apparatus according to the present invention receives a broadcast signal including a first broadcast signal of a weak hierarchy and a second broadcast signal of a strong hierarchy, which is digitally broadcast by hierarchical transmission, at a reception unit having a predetermined number of reception units. A broadcast receiving apparatus that reproduces information based on either the first broadcast signal or the second broadcast signal received by the receiving unit, wherein the reception quality of the broadcast signal at the receiving unit is When the level is lowered to a predetermined switching quality level, the first reproduction form using the first broadcast signal for information reproduction is switched to the second reproduction form using the second broadcast signal for information reproduction, and the reception quality is predetermined. And a playback mode switching means for returning from the second playback mode to the first playback mode when the state exceeding the return quality level is continued for a certain period of time, and information is played back in the second playback mode. In a state A predetermined background process using one or a plurality of receiving units of the predetermined number of receiving units for receiving the broadcast signal related to the reproduction of the information, and using the remaining one or a plurality of receiving units. And the return of the reception quality, which is a condition for returning from the second playback mode to the first playback mode when the background processing by the background processing unit is performed. The time during which the state exceeding the quality level is continued includes a return condition adjusting unit that is set to be shorter than the time when the background processing is not performed.

  With such a configuration, in the second reproduction mode in which information is reproduced using the second broadcast signal of the strong hierarchy, one or a plurality of reception units of a predetermined number of reception units are used for receiving the broadcast signal. On the other hand, when a predetermined background process is performed using the remaining one or a plurality of receiving units, the first reproduction form in which information is reproduced from the second reproduction form using the first broadcast signal of the weak hierarchy. The time during which the state exceeding the return quality level of the reception quality, which is a condition for returning to, is set shorter than the time when the background processing is not performed. In this case, the reception quality of the broadcast signal at the remaining one or more reception units is lower than the reception quality of the broadcast signal at all the predetermined number of reception units, so that the reception quality of the reception quality is restored to the return quality level. Even if the arrival is delayed, the time to continue the return quality level after the reception quality reaches the return quality level becomes shorter.

  In addition, the broadcast receiving apparatus according to the present invention receives a broadcast signal including a first broadcast signal of a weak hierarchy and a second broadcast signal of a strong hierarchy, which is digitally broadcast by hierarchical transmission, in a reception unit having a predetermined number of reception units. A broadcast receiving apparatus that reproduces information based on either the first broadcast signal or the second broadcast signal received at the receiving unit, and receiving the broadcast signal at the receiving unit When the quality is lowered to a predetermined switching quality level, the reception quality is switched from the first reproduction form using the first broadcast signal for information reproduction to the second reproduction form using the second broadcast signal for information reproduction. And a playback mode switching means for returning from the second playback mode to the first playback mode when a state in which a predetermined return quality level is exceeded for a certain period of time, and information playback in the second playback mode. Has been made In one embodiment, one or a plurality of receiving units of the predetermined number of receiving units are used for receiving the broadcast signal related to the reproduction of the information, and the remaining one or more receiving units are used to determine a predetermined background. A background processing means for executing processing and a return condition adjusting means for setting the return quality level lower than the switching quality level are provided.

  With such a configuration, in the second reproduction mode in which information is reproduced using the second broadcast signal of the strong hierarchy, one or a plurality of reception units of a predetermined number of reception units are used for receiving the broadcast signal. On the other hand, when predetermined background processing is performed using the remaining one or a plurality of receiving units, the second reproduction form is changed to the first reproduction form in which information is reproduced using the first broadcast signal of the weak hierarchy. A return quality level, which is a condition for returning, is set lower than a switching quality level, which is a condition for switching from the first playback mode to the second playback mode. In this case, one or a plurality of reception units of a predetermined number of reception units are used for background processing, and the reception quality of the broadcast signals by the remaining reception units is equal to that of the predetermined number of all reception units. Even if the reception quality is lowered, the first reproduction from the second reproduction form to the first reproduction on the basis of the return reception quality level lower than the switching quality level that is a condition for switching from the first reproduction form to the second reproduction form. Return to form is determined.

  In each of the broadcast receiving apparatuses described above, the background process can be a channel search process for searching for a broadcast channel.

  With such a configuration, in the second reproduction mode in which information is reproduced using the second broadcast signal of the strong hierarchy, one or a plurality of reception units of a predetermined number of reception units are used for receiving the broadcast signal. Meanwhile, the channel search process is performed using the remaining one or more receiving units.

  According to the broadcast receiving apparatus according to the present invention, in the second reproduction mode in which the information is reproduced using the second broadcast signal of the strong hierarchy, one or a part of the predetermined number of receiving units for background processing is provided. Even if a plurality of receiving units are used and the reception quality of the broadcast signals by the remaining receiving units is lower than the reception quality of the broadcast signals by the predetermined number of all receiving units, the reduced reception quality level is used as a reference. Since the return from the second playback mode to the first playback mode is determined, the playback of information using the broadcast signal of the strong hierarchy (second playback mode) to the playback of the information using the broadcast signal of the weak hierarchy (second playback mode) The delay in returning to the first reproduction mode) can be minimized.

  Further, according to the broadcast receiving apparatus according to the present invention, in the second reproduction mode in which information is reproduced using the second broadcast signal of the strong hierarchy, a part of a predetermined number of receiving units is used for background processing. One or more reception units are used, and the reception quality of the broadcast signal at the remaining one or more reception units is lower than the reception quality of the broadcast signal at all the predetermined number of reception units. Even if the return quality level is delayed, the time to continue the return quality level after the reception quality reaches the return quality level is shortened. The delay in returning from the (second playback mode) to the playback of information using the broadcast signal of the weak hierarchy (first playback mode) can be minimized.

  Furthermore, according to the broadcast receiving apparatus according to the present invention, in the second reproduction mode in which the information is reproduced using the second broadcast signal of the strong hierarchy, a part of the predetermined number of receiving units is used for background processing. Even if one or a plurality of reception units are used and the reception quality of the broadcast signals by the remaining reception units is lower than the reception quality of the broadcast signals by all the predetermined number of reception units, the first reproduction form to the second reproduction form Since the return from the second playback mode to the first playback mode is determined on the basis of the return reception quality level lower than the switching quality level, which is a condition for switching to, information using a broadcast signal of a strong hierarchy From the reproduction (second reproduction form) to the reproduction of information using the broadcast signal of the weak hierarchy (first reproduction form) can be minimized.

It is a block diagram which shows the structure of the terrestrial digital broadcast receiver which is a broadcast receiver which concerns on embodiment of this invention. It is a flowchart which shows an example of the automatic switching process of the full segment reproduction | regeneration form and the one segment reproduction | regeneration form in the control part of the broadcast receiver shown in FIG. 2 shows the relationship between the change in reception quality (C / N) and the switching between the full segment reproduction mode and the one segment reproduction mode when the automatic switching process between the full segment reproduction mode and the one segment reproduction mode is performed according to the procedure shown in FIG. FIG. It is a flowchart which shows the procedure of the channel search process (background process) by the control part of the vehicle-mounted receiving apparatus shown in FIG. Reception quality (C / N) and full segment reproduction mode when a relay channel is found in the channel search process executed in the process of automatically switching between the full segment reproduction mode and the one segment reproduction mode according to the procedure shown in FIG. 5 is a timing chart showing the relationship between switching between the one-segment playback mode and channel search. It is a flowchart which shows another example of the automatic switching process of the full segment reproduction | regeneration form and the one segment reproduction | regeneration form in the control part of the broadcast receiver shown in FIG. Reception quality (C / N) and full-seg playback mode when a relay channel is found in the channel search process executed in the process of automatically switching between the full-seg playback mode and the one-seg playback mode according to the procedure shown in FIG. 5 is a timing chart showing the relationship between switching between the one-segment playback mode and channel search.

  An embodiment of the present invention will be described with reference to the drawings.

  The broadcast receiving apparatus according to the embodiment of the present invention is an in-vehicle terrestrial digital broadcast receiving apparatus and is configured as shown in FIG.

  A broadcast receiving apparatus (terrestrial digital broadcast receiving apparatus) 10 shown in FIG. 1 can receive terrestrial digital broadcasts. In this terrestrial digital broadcasting, as described above, the information rate using 12 segments out of 13 segments included in one channel is large (for example, by multi-level QAM) due to hierarchical transmission. A broadcast signal (hereinafter referred to as a full-segment broadcast signal (first broadcast signal)) and a strong hierarchical broadcast signal (hereinafter referred to as QPSK) modulated in a manner that is resistant to fluctuations in radio waves using the remaining one segment (hereinafter referred to as QPSK). A broadcast signal including a one-segment broadcast signal (referred to as a second broadcast signal) is provided for broadcasting. This broadcast signal is transmitted as an OFDM signal in which a plurality of carriers modulated based on information to be broadcast (audio, video, data, etc.) are converted into OFDM (Orthogonal Frequency Division Multiplexing).

  As shown in FIG. 1, a broadcast receiving apparatus 10 that receives the broadcast signal (OFDM signal) that is hierarchically transmitted includes a control unit 11 and four tuner units (reception units) 12a, 12b, 12c, and 12d. 12, a switching unit 13, a first OFDM demodulating unit 14a, a second OFDM demodulating unit 14b, a decoder 15, a display processing unit 16, and a digital / analog converter (D / A converter) 17. The control unit 11 includes a reception state determination unit 111, a switching control unit 112, a search processing unit 113, and an EPG creation unit 114. The broadcast receiving apparatus 10 is connected to a center unit 20 provided on the instrument panel. The center unit 20 includes a display device 21 and an operation unit 22, and a speaker 25 is connected to the center unit 20.

  Each of the four tuner units 12a to 12d constituting the receiving unit 12 selects a transmission channel and receives a broadcast signal (OFDM signal) of the selected transmission channel. This broadcast signal includes the above-described full-segment broadcast signal (first broadcast signal) in the weak hierarchy and the one-segment broadcast signal (second broadcast signal) in the strong hierarchy. Under the control of the switching control unit 112 in the control unit 11, the switching unit 13 maintains a state in which broadcast signals from the two tuner units 12a and 12b are constantly supplied to the first OFDM demodulation unit 14a, while The broadcast signals from the two tuner units 12c and 12d are switched to one of the first OFDM demodulator 14a and the second OFDM demodulator 14b.

  Each of the first OFDM demodulator 14a and the second OFDM demodulator 14b demodulates a broadcast signal (OFDM signal) input via the switching unit 13 to generate a digital reception signal (transport packet). The control unit 11 performs diversity combining of a plurality of (four or two) digital reception signals from the first OFDM demodulation unit 14a according to a predetermined algorithm, and an audio signal and a video signal are obtained from the combined reception signal obtained thereby. And other signals (data, EPG information, etc.). Then, the control unit 11 supplies the audio signal and the video signal to the decoder 15, and internally processes other signals such as data and EPG information. The decoder 15 decodes the audio signal and the video signal from the control unit 11. The decoded video signal obtained by decoding by the decoder 15 is subjected to predetermined display processing by the display processing unit 16 and is supplied to the center unit 20. The decoded audio signal obtained by decoding by the decoder 15 is converted to an analog audio signal by the D / A converter 17 and supplied to the center unit 20.

  In the center unit 20, the video of the broadcast program is displayed on the display device 21 based on the decoded video signal from the display processing unit 16, and the audio of the broadcast program is output from the speaker 25 based on the decoded audio signal.

  The reception state determination unit 111 in the control unit 11 receives the broadcast signal (OFDM signal) reception quality, for example, the ratio between the carrier power (C) and the noise power (N) based on the combined received signal obtained by diversity combining. C / N is calculated as a parameter representing reception quality, and reception quality is determined based on this CN. The search processing unit 113 in the control unit 11 searches for a receivable channel based on the digital reception signal from the second OFDM demodulation unit 14b that demodulates the broadcast signals (OFDM signals) from the two tuner units 12c and 12d. Perform the channel search process. Details of this channel search process will be described later. The EPG creation unit 114 is an EPG (electronic program guide) based on the EPG information separated from the digital reception signal from the second OFDM demodulation unit 14b that demodulates the broadcast signals (OFDM signals) from the two tuner units 12c and 12d. Process to create. The channel search process by the search processing unit 113 and the EPG creation process by the EPG creation unit 114 are performed in the background of the process related to reproduction (output) of information (audio, video) based on the received broadcast signal, for example. Can do.

  The control unit 11 includes a full-seg playback mode (first playback mode) that uses a weak-segment full-segment broadcast signal for information playback, and a one-segment playback mode (second playback mode) that uses a strong-layer one-segment broadcast signal for information playback. Are switched according to the reception quality determined by the reception state determination unit 111 (reproduction form switching means). For example, in the full segment playback mode, the control unit 11 supplies a portion corresponding to the full segment broadcast signal to the decoder 15 in the combined reception signal obtained by diversity combining, and in the one segment playback mode, the control unit 11 receives the combined reception signal obtained by diversity combining. A portion corresponding to the one-segment broadcasting signal is supplied to the decoder 15. Switching between the full-segment reproduction mode and the one-segment reproduction mode in the control unit 11 is performed, for example, according to the procedure shown in FIG.

  In FIG. 2, the reception state determination unit 111 determines whether or not the reception quality represented by C / N is equal to or lower than the first quality level (threshold) Th1 (S11). If the reception state determination unit 111 determines that the reception quality is good and not lower than the first quality level Th1 (NO in S11), the control unit 11 maintains the full segment reproduction mode (S12). As a result, in a reception environment in which the reception quality (C / N) exceeds the first quality level Th1 and the reception environment is good, the full segment playback mode is maintained, and high-quality video and audio playback based on the weak segment full segment broadcast signal ( Video display on the display device 21 and sound output from the speaker 25).

  The vehicle travels and the reception environment of the broadcast signal deteriorates. For example, at time t1 in FIG. 3, the reception state determination unit 111 causes the reception quality (C / N) to be equal to or lower than the first quality level Th1 (switching quality level). If it is determined that there is (YES in S11), the control unit 11 switches from the full-segment playback mode to the one-segment playback mode (S13: playback mode switching means). As a result, when the reception environment of the broadcast signal is poor and the reception quality (C / N) is reduced to the first quality level Th1 (switching quality level), the one-segment playback mode is switched to a strong hierarchical one-segment broadcasting that is resistant to noise and the like. Information (audio, video) is reproduced (video display, sound output) using the signal.

  Thereafter, the control unit 11 determines whether or not a channel search process (background process) described later is performed in the background (S14). If the channel search process is not performed (NO in S14), the control unit 11 sets the same quality level (Th1) as the first quality level Th1 (switching quality level), which is a condition for switching from the full segment playback mode to the one segment playback mode. The return quality level Thx of the return condition for returning from the one-segment playback mode to the full-segment playback mode is set (S15). Then, the control unit 11 determines whether or not the reception quality (C / N) exceeds the return quality level Thx (= Th1) (S16). If the reception quality (C / N) does not recover and does not exceed the return quality level Thx (= Th1) (NO in S16), the control unit 11 confirms that the timer T described later is zero. (YES in S17), the one-segment playback mode is maintained (S18).

  In the state where the channel search process is not performed, the control unit 11 further sets the first quality level Th1 as the return quality level Thx (NO in S19) and the channel search process is not performed (NO in S14). ) And the above-described processing (S16 to S18) is executed while maintaining the return quality level Thx at the first quality level T1 (S15). As a result, in a state where the reception quality has not reached the first quality level Th1 set as the return quality level Thx (NO in S16), the one-segment playback mode is maintained (S18).

  In a state where the one-segment playback mode is maintained without performing the channel search process, the reception environment of the broadcast signal is improved by traveling of the vehicle, and the reception quality (C / N) is the return quality level Thx (= the first). If it exceeds 1 (quality level Th1) (YES in S16), the controller 11 determines whether or not the timer T is zero (T = 0) (S22), and if the timer T is zero (S22) (YES), the timer T is started (S23), and it is determined whether or not the timer T has reached a predetermined time To (S24). If the timer T has not reached the predetermined time To (NO in S24), the control unit 11 maintains the one-segment playback mode (S18). Thereafter, even when the reception quality (C / N) exceeds the return quality level Thx (= Th1) and the reception environment is good (YES in S16), the one-segment playback mode is maintained while the timer T operates. (S14 to S16, S22 to S24, S18 to S19).

  In situations where the broadcast signal reception environment is unstable, the reception quality (C / N) may temporarily drop below the return quality level Thx (= Th1). In this case (NO in S16), the control unit 11 confirms that the timer T is not zero (NO in S17), resets the timer T (S21), and further maintains the one-segment playback mode (S18). Thereafter, when the reception quality (C / N) exceeds the return quality level Thx (= Th1) again due to the recovery of the broadcast signal reception environment (YES in S16), the control unit 11 confirms that the timer T is zero. After confirming (YES in S22), the timer T is started again (S23). Then, the control unit 11 determines whether or not the timer T has reached the predetermined time To (S24). If the timer T has not reached the predetermined time To (NO in S24), the reception quality (C / N) Is over the return quality level Thx (= Th1), but the one-segment playback mode is maintained (S18).

  For example, as in the situation between time t1 and time t2 in FIG. 3, a state where the reception quality (C / N) exceeds the first quality level Th1 (return reception level Thx) cannot be maintained for a predetermined time To. In a situation where the reception environment of the broadcast signal is unstable, the start of the timer T (YES in S16, S22, S23, S24) and the reset (NO in S16, NO in S17, S21) are repeated, and the one-segment playback mode Is maintained (S18). Accordingly, in such a situation where the reception environment of the broadcast signal is unstable, information (audio, video) is reproduced (video display, sound output) using a one-segment broadcast signal of a strong hierarchy resistant to noise or the like.

  In the situation where the one-segment playback mode is maintained as described above (S18), the broadcast signal reception environment is improved, and the reception quality (C / N) exceeds the return quality level Thx (= Th1) ( If the timer T reaches the predetermined time To (YES in S16) (YES in S24), that is, the reception quality (C / N) is the return quality as in the situation between the time t2 and the time t3 in FIG. When the state exceeding the level Thx (= Th1) continues for a predetermined time To, the control unit 11 returns from the one-segment reproduction mode to the full-segment reproduction mode (S25: see time t3 in FIG. 3). This makes it possible to reproduce high-quality video and audio based on weak-segment full-segment broadcast signals from information (audio and video) reproduction (video display, sound output) using strong-segment one-segment broadcast signals that are resistant to noise, etc. (Video display, sound output).

  As described above, according to the reception quality (C / N), in the process of reproducing information (video, audio) while switching between a high-quality full-segment reproduction form and a one-segment reproduction form with poor quality. The control unit 11 executes the channel search process as a background process, for example, according to the procedure shown in FIG.

  For example, as shown in FIG. 5, the reception quality (C / N) is reduced to the first quality level Th1 (switching quality level), and the reproduction of information (video information, audio information) is changed from the full-segment reproduction form to the one-segment reproduction form. In the switched state, except for a predetermined case (for example, when an operation mode in which channel search processing is not performed is set by the user, or when reception quality is significantly deteriorated), for example, the one-segment playback mode is used. At a certain timing (time t11) after switching (time t1), the channel search process is executed.

  When the switching control unit 112 in the control unit 11 controls the switching unit 13, two tuner units 12a and 12b among the four tuner units 12a to 12d are connected to the first OFDM demodulating unit 14a. The remaining two tuner units 12c and 12d are connected to the second OFDM demodulator unit 14b and used for channel search. In parallel with the reproduction of information (video, audio) in the one-segment reproduction format using the broadcast signals of the channels selected by the two tuner units 12a and 12b, the control unit 11 (search processing unit 113) The remaining tuner units 12c and 12d are controlled to perform channel search processing (background processing) according to the procedure shown in FIG. The broadcast signal of the channel that has been selected so far has been received using the four tuner units 12a to 12d and has been combined with diversity (four-diversity combining). Since the reception is switched to reception using 12a and 12b, the reception quality (C / N) of the broadcast signal of the channel that has been selected until now, which is continued after the start of the channel search process, is, for example, the channel search period shown in FIG. It slightly decreases from the characteristic indicated by the broken line at (time t11 to time t21) as indicated by the solid line (however, within the quality level range in which information can be reproduced in the one-segment reproduction form).

  In FIG. 4, the search processing unit 113 (background processing means) in the control unit 11 selects and sets one channel frequency from the receivable frequency band defined in the already received NIT (Network Information Table). Then, it is determined whether or not the broadcast signal (OFDM signal) of the set channel frequency is received by the two tuner units 12c and 12d (S32). When the broadcast signal (OFDM signal) of the set channel frequency cannot be received (NO in S32), the search processing unit 113 is used in the switching process between the full segment reproduction mode and the one segment reproduction mode shown in FIG. It is determined whether or not the timer T has reached a predetermined time To (S36). If the reproduction of information in the one-segment reproduction mode is maintained and the timer T has not reached the predetermined time To (NO in S36), the search processing unit 113 has finished searching for all channels. It is determined whether or not (S37).

  If the search for all channels has not been completed (NO in S37), the search processing unit 113 sets the next channel frequency (S31), and the broadcast signal (OFDM signal) of the set channel frequency has two tuners. It is determined whether it is received by the units 12c and 12d (S32). When a broadcast signal (OFDM signal) of the set channel frequency is received by the two tuner units 12c and 12d (YES in S32), the search processing unit 113 uses the received broadcast signal to obtain information in a full segment reproduction form. Is determined, that is, whether or not the reception quality (C / N) exceeds the first quality level Th1 (switching quality level) (S33). Here, based on the reception results of the two tuner units 12c and 12d, the reception quality when the four tuner units 12a to 12d receive and combine the diversity is estimated and determined. When it is determined that the reception quality (estimated reception quality) is equal to or lower than the first reception quality level Th1 and the information cannot be reproduced in the full-segment reproduction form by the received broadcast signal (NO in S33). After confirming that the timer T has not reached the predetermined time To (NO in S36) and that the search of all channels has not been completed (NO in S37), the search processing unit 113 performs the next channel frequency. Is set (S31).

  Furthermore, when the broadcast signal (OFDM signal) of the next set channel frequency is received (YES in S32), it is determined that the information can be reproduced in the full segment reproduction form by the received broadcast signal ( In S33, the search processing unit 113 broadcasts the channel of the received broadcast signal that is currently selected and the information (broadcast program video, broadcast program audio) is reproduced in a one-segment playback format. It is determined whether or not the relay channel is broadcasting the same program as the signal channel (S34). If it is determined that the channel of the received broadcast signal is not a relay channel (NO in S34), the timer T has not reached the predetermined time To (NO in S36), and all channels are searched. After confirming that is not completed (NO in S37), the search processing unit 113 further sets the next channel frequency (S31).

  In this way, the search processing unit 113 confirms that the timer T has not reached the predetermined time To (S36), sequentially changes the channel frequency (S37, S31), and the broadcast signal of that channel frequency is fully segmented. It is determined whether or not it is a broadcast signal of a relay channel capable of reproducing information in a reproduction form (S32 to S34). In the process, if it is determined that the broadcast signal of the set channel frequency is a broadcast signal of a relay channel capable of reproducing information in the full segment reproduction form (YES in S32, YES in S33, YES in S34), search processing The unit 113 decides to select the relay channel as a channel to be received and reproduced instead of the currently selected channel (S35), and ends the channel search process.

  In the situation where the full segment playback mode is switched to the one segment playback mode according to the procedure shown in FIG. 2 (S13), and the channel search process (see FIG. 4) described above is performed, the control unit 11 performs the channel search process by the search processing unit 113. Is confirmed (YES in S14), the second quality level Th2 lower than the first quality level Th1 (switching quality level), which is a condition for switching from the full-seg playback mode to the one-seg playback mode, is changed from the one-segment playback mode to the full-seg mode. It is set as the return quality level Thx of the return condition for returning to the reproduction mode (S20). This means that the return quality level Thx (= Th2) is lower than the return quality level Thx (= Th1) when the above-described channel search process is not performed.

  Thereafter, the control unit 11 performs the same procedure as described above (YES in S16, S17, S18, S19, or S16, S22 to S24, S18, S19, or NO in S16, S17, S21, S18, S19). ) To maintain the one-segment playback mode. In the process, a relay channel with good reception quality is found in the channel search process, and broadcasts are received by the two tuner sections 12a and 12b other than the two tuner sections 12c and 12d used in the channel search process. For example, the signal reception quality exceeds the set relatively low return quality level Thx (= second quality level Th2) at time t2 shown in FIG. 5 (YES in S16). When the state exceeding the return quality level Thx (= second quality level Th2) continues for a predetermined time To (YES in S24), the control unit 11 returns from the one-segment reproduction mode to the full-segment reproduction mode (S25: time in FIG. 5). t3). When a relay channel with good reception quality is found by the channel search process, the channel search process ends (time t21 in FIG. 5) before returning to the full segment reproduction mode (time t3 in FIG. 5), and all the tuner units 12a to 12a. Information (sound, video) is reproduced using the broadcast signal (one-segment broadcast signal) of the relay channel received at 12c. Then, from the time of switching to the full segment playback mode (time t3 in FIG. 5), switching to high quality video and audio playback based on the weak cell full cell broadcast signal included in the broadcast signal of the relay channel is performed.

  In the broadcast receiving apparatus 10 (vehicle-mounted terrestrial digital broadcast receiving apparatus) as described above, in the one-segment playback mode in which information is reproduced using a one-segment broadcasting signal of a strong hierarchy, among the four tuners 12 parts a to 12d When the channel search process (background process) is performed using the remaining two tuner units 12c and 12d while the two tuner units 12a and 12b are used for receiving broadcast signals, the full segment of the weak hierarchy is changed from the one-segment playback mode. The return quality level Thx, which is a condition for returning to the full segment playback mode in which information is reproduced using broadcast signals, is set to the return quality level Thx (= first quality level Th1) when the background processing is not performed. Compared to the full-seg playback mode and the one-seg playback mode at the same time, That switching quality level (first quality level) is set to the second quality level Th2 lower than that of Th1. In this case, two tuner units 12c and 12d out of the four tuner units 12a to 12d are used for the channel search process, and the reception quality of the broadcast signal by the two tuner units 12a and 12b is all four tuner units. Even if the reception quality is lower than the broadcast signal reception quality of 12a to 12d, the return from the one-segment playback mode to the full-segment playback mode is determined based on a relatively low return reception quality level (= Th2 <Th1). Therefore, it is possible to minimize the delay in returning from information reproduction (one-seg reproduction form) using the strong layer one-segment broadcast signal to information reproduction (full-segment reproduction form) using the weak layer full-segment broadcast signal.

  The control unit 11 can switch between the full segment reproduction mode and the one segment reproduction mode according to the procedure shown in FIG. 6 instead of the procedure shown in FIG. In this example, the channel search process is performed when the time (recovery quality duration) in which the reception quality, which is the condition for returning from the one-segment playback mode to the full-segment playback mode, continues to exceed the return quality level is performed. It is characterized in that it is shorter than when processing is not performed. In FIG. 6, the same reference numerals as the reference numerals indicating the steps in FIG. 2 indicate the same steps.

  In FIG. 6, when the channel search process is not performed, when the reception quality becomes equal to or lower than the switching quality level Th1 (for example, time t1 in FIG. 3), the full segment playback mode is switched to the one segment playback mode (S11 to S13). The time during which the reception quality, which is the return condition from the playback mode to the full segment playback mode, exceeds the return quality level, that is, the return quality duration Tx is set to To (S151). In addition, the return quality level that is the return condition from the one-segment playback mode to the full-segment playback mode is the same as the switching quality level Th1 (see S16) that is the switching condition from the full-segment playback mode to the one-segment playback mode. For this reason, when the channel search process is not performed, processes substantially similar to the process shown in FIG. 2 (S11 to S14, S151, S16 to S18, S191, S21, S22 to S24, and S25) are performed. As a result, as shown in FIG. 3, when the reception quality of the broadcast signals received by the four tuner units 12a to 12d falls below the switching quality level Th1 (time t1), the full-segment playback mode is switched to the one-segment playback mode. Thereafter, when the reception quality exceeds the same return quality level Th1 as the switching quality level (time t2), and the state where the reception quality exceeds the return quality level Th1 continues for the time To set as the return quality duration time To. At (time t3), the one-segment playback mode is restored to the full-seg playback mode.

  On the other hand, when the full-segment playback mode is switched to the one-segment playback mode and the channel search process (see FIG. 4) described above is performed, the control unit 11 confirms that the channel search process by the search processing unit 113 is performed. (YES in S14), the return quality continuation time Tx, which is a condition for switching from the full segment playback mode to the one segment playback mode, is set to a time T1 shorter than the predetermined time To (S201).

  Thereafter, the control unit 11 performs the same procedure as described above (YES in S16, S17, S18, S191, or S16, S22 to S24, S18, S191, or NO in S16, S17, S21, S18, S191). ) To maintain the one-segment playback mode. In the process, a relay channel with good reception quality is found in the channel search process, and broadcasts are received by the two tuner sections 12a and 12b other than the two tuner sections 12c and 12d used in the channel search process. For example, as shown in FIG. 7, at a time t <b> 21 that is delayed from a time t <b> 2 that is expected when the channel search process is not performed (four tuner units 12 a to 12 d are used for broadcast reception). The return quality level Th1 (= switching quality level) is exceeded (YES in S16). When the state in which the reception quality exceeds the return quality level Th1 continues for the time set as the return quality duration time Tx (= T1 <To) (YES in S24), the one-segment playback mode returns to the full-seg playback mode. (S25: Time t3 in FIG. 7).

  Also in this case, as in the case shown in FIG. 5, when a relay channel with good reception quality is found by the channel search process, the channel search process is completed before returning to the full segment reproduction mode (time t3 in FIG. 7). Then (at approximately time t21 in FIG. 7), information (audio, video) is reproduced using the broadcast signal (one-segment broadcast signal) of the relay channel received by all the tuner units 12a to 12c. Then, from the time of switching to the full-segment playback mode (time t3 in FIG. 7), switching to high-quality video and audio playback based on the weak-segment full-segment broadcast signal included in the broadcast signal of the relay channel is performed.

  In the broadcast receiving apparatus 10 (vehicle-mounted terrestrial digital broadcast receiving apparatus) that switches between the full-segment playback mode and the one-segment playback mode according to the procedure shown in FIG. 6, information is played back using a strong-layer one-segment broadcasting signal. In the reproduction mode, two tuner units 12a and 12b among the four tuner units 12a to 12d are used for receiving broadcast signals, while channel search processing (background processing) is performed using the remaining two tuner units 12c and 12d. In the case where the reception quality is made, the state of exceeding the return quality level of the reception quality, which is a condition for returning from the one-segment playback mode to the full-seg playback mode in which information is reproduced using the full-segment broadcasting signal of the weak layer, is continued. When the background processing is not performed, the return duration Tx defined as It is set to the time shorter than To time T1. In this case, since the reception quality of the broadcast signal at the two tuner sections 12a and 12b is lower than the reception quality of the broadcast signal at all four tuner sections 12a to 12d, the return quality level of the reception quality is reduced. Even if the arrival at Th1 is delayed, the time Tx at which the return quality level should continue after the reception quality reaches the return quality level Th1 becomes shorter. Therefore, it is possible to minimize the delay in returning from information reproduction (one-seg reproduction form) using the strong layer one-segment broadcast signal to information reproduction (full-segment reproduction form) using the weak layer full-segment broadcast signal.

  In the above-described example, the channel search process is executed as the background process, but other processes such as a process for acquiring EPG information (a process in the EPG creation unit 114) are performed in the background. It may be executed as a process.

  Further, both the return quality level Thx and the return continuation time Tx when the background process is executed may be set lower and shorter than those when the background process is not executed.

  The broadcast receiving apparatus according to the present invention has the effect that the delay in returning from the reproduction of information using a strong hierarchy broadcast signal to the reproduction of information using a weak hierarchy broadcast signal can be reduced as much as possible. It is useful as a broadcast receiving apparatus that performs background processing such as channel search while receiving weak-layer broadcast signals and strong-layer broadcast signals that are digitally broadcast by hierarchical transmission as in terrestrial digital broadcasting.

DESCRIPTION OF SYMBOLS 10 Broadcast receiving apparatus 11 Control part 12 Receiving part 12a-12b Tuner part 13 Switching part 14a 1st OFDM demodulation part 14b 2nd OFDM demodulation part 15 Decoder 16 Display processing part 17 Digital / analog converter (D / A converter) )
20 Center unit 21 Display device 22 Operation unit 25 Speaker 111 Reception state determination unit 112 Switching control unit 113 Search processing unit 114 EPG creation unit

Claims (4)

A broadcast signal including a first broadcast signal of a weak hierarchy and a second broadcast signal of a strong hierarchy that is digitally broadcast by hierarchical transmission is received by a reception unit having a predetermined number of reception units, and is received by the reception unit. A broadcast receiving device for reproducing information based on either the first broadcast signal or the second broadcast signal,
When the reception quality of the broadcast signal at the receiving unit is lowered to a predetermined switching quality level, the second broadcast signal is used for information reproduction from the first reproduction form using the first broadcast signal for information reproduction. Switching to the second playback mode, and when the reception quality exceeds a predetermined return quality level for a certain period of time, playback mode switching means for returning from the second playback mode to the first playback mode;
In a state where information is reproduced in the second reproduction form, one or a plurality of reception units of a part of the predetermined number of reception units are used for receiving the broadcast signal related to reproduction of the information, and the rest Background processing means for executing predetermined background processing using one or a plurality of receiving units;
A broadcast receiving apparatus comprising: return condition adjustment means for setting the return quality level when the background processing is performed by the background processing means to be lower than the return quality level when the background processing is not performed. A broadcast signal including a first broadcast signal of a weak hierarchy and a second broadcast signal of a strong hierarchy that is digitally broadcast by hierarchical transmission is received by a reception unit having a predetermined number of reception units, and is received by the reception unit. A broadcast receiving device for reproducing information based on either the first broadcast signal or the second broadcast signal,
When the reception quality of the broadcast signal at the receiving unit is lowered to a predetermined switching quality level, the second broadcast signal is used for information reproduction from the first reproduction form using the first broadcast signal for information reproduction. Switching to the second playback mode, and when the reception quality exceeds a predetermined return quality level for a certain period of time, playback mode switching means for returning from the second playback mode to the first playback mode;
In a state where information is reproduced in the second reproduction form, one or a plurality of reception units of a part of the predetermined number of reception units are used for receiving the broadcast signal related to reproduction of the information, and the rest Background processing means for executing predetermined background processing using one or a plurality of receiving units;
When the background processing by the background processing means is performed, the state of the reception quality exceeding the return quality level being a condition for returning from the second playback mode to the first playback mode is continued. The broadcast receiving apparatus further includes a return condition adjusting unit that sets a time shorter than the time when the background processing is not performed. A broadcast signal including a first broadcast signal of a weak hierarchy and a second broadcast signal of a strong hierarchy that is digitally broadcast by hierarchical transmission is received by a reception unit having a predetermined number of reception units, and is received by the reception unit. A broadcast receiving device for reproducing information based on either the first broadcast signal or the second broadcast signal,
When the reception quality of the broadcast signal at the receiving unit is lowered to a predetermined switching quality level, the second broadcast signal is used for information reproduction from the first reproduction form using the first broadcast signal for information reproduction. Switching to the second playback mode, and when the reception quality exceeds a predetermined return quality level for a certain period of time, playback mode switching means for returning from the second playback mode to the first playback mode;
In a state where information is reproduced in the second reproduction form, one or a plurality of reception units of a part of the predetermined number of reception units are used for receiving the broadcast signal related to reproduction of the information, and the rest Background processing means for executing predetermined background processing using one or a plurality of receiving units;
A broadcast receiving apparatus comprising: return condition adjusting means for setting the return quality level lower than the switching quality level.   The broadcast receiving apparatus according to claim 1, wherein the background process is a channel search process for searching for a broadcast channel.

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