JP2008147842A - Digital broadcast receiving device and control method thereof, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital broadcast receiving device capable of relaxing user's dissatisfaction with a failure in displaying a program of a target channel after channel switching. <P>SOLUTION: The digital broadcast receiving device 90 includes pluralities of pairs of tuners and decoders (100, 104) and (102, 106) which receive digital broadcast signals, select and decode digital broadcast signals of specified channels, and output video signals, a switching circuit 118 which selects a video signal specified with a select signal out of their outputs and outputs the video signal to a display 92, and maintains the selection until a next select signal is supplied, and a CPU 110 which controls the switching circuit 118 so as to make one of the plurality of the pairs (100, 104) and (102, 106) of the tuners and decoders start selecting the specified channel and performing decoding in response to the reception of a channel switching indication, and selects the output of a normal video signal when the output of the normal video signal becomes possible. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for improving video display of a television (hereinafter referred to as “TV”), and more particularly to a technique for improving video display when a channel is switched in digital television broadcasting.

  Instead of analog TV broadcasts so far, all TV broadcasts are being digitized. By digitizing TV broadcasting, it is possible to use many channels that are less affected by noise while effectively using radio wave bands.

  In order to use the band effectively, digital television broadcasting encodes images. For image coding, predictive coding techniques such as intraframe predictive coding and interframe predictive coding are employed. By adopting such a technique, it is possible to perform digital television broadcasting with clear image quality while reducing the amount of data to be transmitted.

  However, the use of the predictive coding method has the following disadvantages. That is, since the predictive coding technique is employed, an image that precedes the image may be required in order to create an image of a certain frame. For this reason, a certain time is required to first receive and decode a digital television broadcast signal of a certain broadcasting station. The video cannot be reconstructed from only the signals received during this time. Therefore, nothing is displayed on the screen until a specific image frame that does not depend on the previous image is received after the channel is switched. Although this time is short, there is a problem in that the user panics because the screen becomes dark immediately after switching the channel.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2004-151620, which will be described later, discloses a technique for displaying a message such as “Channel switching in progress” on the screen until the video display of the target channel becomes possible after the channel is switched. It is disclosed. By displaying such a message, at least the user can understand that the television receiver is not malfunctioning.

On the other hand, even the technique disclosed in Patent Document 1 has a problem that it is not possible to enjoy video for a certain period of time after channel switching. One measure for solving such a problem is disclosed in Patent Document 2 described later. The digital broadcast receiving apparatus disclosed in Patent Document 2 has two tuners, and while receiving a broadcast of a broadcast station that is one tuner, the other tuner buffers a program of another broadcast channel. Keep it. When a channel is switched and a buffered channel is selected, the buffered video is output immediately. Therefore, in this case, it is possible to prevent the screen from becoming dark. However, if a broadcast station different from the buffered broadcast station is selected after channel switching, the problem remains that the screen is not displayed for a certain period of time.
JP 2006-50553 A JP 2006-67599 A

  In the device disclosed in Patent Document 1, since the message is displayed after the channel is switched, the user is less likely to misunderstand that the device has failed. However, until the target channel is displayed, there is a complaint that the user has missed a television broadcast that should have been enjoyed.

  On the other hand, in the device disclosed in Patent Document 2, when the channel selected by the user matches the channel predicted by the device, the video is immediately displayed, so that the user is not dissatisfied. However, if the prediction is wrong, the video is not displayed at all as usual, and in this case, the user is also dissatisfied.

  Therefore, an object of the present invention is to alleviate user dissatisfaction caused by the fact that a program of a target channel is not displayed in a certain period of time after channel switching, regardless of the channel to which the channel is switched. It is to provide a digital television broadcast receiving apparatus that can be used.

  A digital broadcast receiving apparatus according to a first aspect of the present invention includes a plurality of video decoding means for decoding a video signal included in a digital broadcast signal of a designated channel, and any one of the plurality of video decoding means. The video signal output from the video decoding means specified by the selection signal is selected from the video signals output from the plurality of video decoding means in response to the selection signal specifying one of them, and is output to the display unit. In response to receiving a channel switching instruction from the user, a selection means for maintaining selection by the preceding selection signal until a signal is given, and a first video decoding means among the plurality of video decoding means The decoding of the video signal included in the digital broadcast signal of the channel designated by the channel switching instruction is started, and the first video decoding means outputs a normal video signal. And responsive to a potential, and a control means for providing a selection signal to the selection means to select the output of the first video decoding unit.

  In this digital broadcast receiving apparatus, each of the plurality of video decoding means decodes a video signal included in a digital broadcast signal of a designated channel. The selection means selects the video signal output from the video decoding means designated by the preceding selection signal and outputs it to the display unit until a selection signal is given from the user. When receiving a channel switching instruction from the user, the control means causes the first video decoding means to start decoding the video signal included in the digital broadcast signal of the channel designated by the channel switching instruction. However, during this time as well, the selection signal selects and outputs the output of the video decoding means selected before the channel switching instruction. When the first video decoding means can output a normal video signal, the control means gives a selection signal to the selection means to select the output of the first video decoding means.

  When the user gives a channel switching instruction, the first video decoding means starts decoding the video signal of that channel. For digital broadcast signals, normal video signal decoding by the first video decoding means is not immediately possible. However, until then, the selection means outputs the video signal from the video decoding means designated by the previous selection signal to the display unit. Therefore, the screen displayed on the display unit during this time can be prevented from being completely dark. As a result, it is possible to prevent the user from misunderstanding that the screen is dark after the channel switching operation and the apparatus has failed. When the normal video signal can be output by the first video decoding means, the control means controls the selection means to select the output. As a result, the video signal of the channel decoded by the first video decoding means is displayed for the first time when a normal video signal can be output. Until this video signal is displayed, since the video of the channel before switching is displayed, user dissatisfaction that no information is given along with the channel switching can be alleviated.

  Preferably, in response to receiving a channel switching instruction from the user, the control means sends a digital broadcast signal of a channel designated by the channel switching instruction to the first video decoding means of the plurality of video decoding means. Digital broadcast of a channel indicated by the channel selection signal is generated by a channel selection signal output unit for outputting a channel selection signal for starting decoding of the included video signal and a first video decoding unit receiving the channel selection signal. Means for providing a selection signal to the selection means so as to select the output of the first video decoding means in response to the normal decoding of the video signal included in the signal. The selecting means is a signal processing means for executing a predetermined processing on the selected video signal in response to the channel selection signal, and outputs from the plurality of video decoding means; and Until the channel selection signal or selection signal is given, the output indicated by the preceding channel selection signal or selection signal is selected and the signal processing is performed in response to the channel selection signal. And switching means for switching input / output so as to select the output of the video decoding means designated by the selection signal in response to the selection signal.

  When receiving the channel switching instruction, the control means causes the first video decoding means to start decoding the video signal included in the digital broadcast signal of the designated channel. With this decoding, a normal video signal cannot be output immediately. However, until then, the video signal of the channel before the channel switching is processed and output to the display unit as follows. That is, a channel selection signal is given to the signal processing means, and the signal processing means performs predetermined processing on the video signal being selected by the selection means and outputs it. When the channel selection signal is given, the switching means enables the normal video signal to be output by the first video decoding means, and selects the output of the signal processing means until the selection signal is given from the control means. Output. Further, the normal video signal can be output by the first video decoding means, and when the selection signal is given from the control means, the switching means selects the normal video signal output by the first video decoding means. Give to the display.

  When there is a channel switching instruction by the user, the video signal of the channel selected up to the channel switching instruction is subjected to predetermined processing until the normal output of the video signal of the new channel becomes possible. Is displayed. When normal output of the video signal of the new channel becomes possible, the video signal of the new channel is further selected and displayed on the display unit. The user can view a video in which a predetermined processing has been performed on the video signal of the previously selected channel until the video signal of the new channel is displayed after the channel switching instruction is given. it can. As a result, it is possible to prevent the screen from becoming dark immediately after the channel switching instruction is given, and further, it is understood that the channel switching process is being performed due to the processing being performed on the image, and there is a possibility that it may be mistaken for a failure. There is an effect that it decreases.

  A control method of a digital broadcast receiving apparatus according to a second aspect of the present invention includes a plurality of video decoding means for decoding a video signal included in a digital broadcast signal of a designated channel, and a plurality of video decoding means In response to the selection signal designating one of them, the video signal output from the video decoding means specified by the selection signal is selected from the digital broadcast signals output from the plurality of video decoding means and output to the display unit. A digital broadcast receiving apparatus control method for changing a channel in a digital broadcast receiving apparatus including selection means for maintaining selection by a preceding selection signal until a next selection signal is given, In response to receiving the channel switching instruction from the user, the first video decoding means of the plurality of video decoding means is instructed by the channel switching instruction. A step of starting decoding of the video signal included in the digital broadcast signal of the selected channel, and maintaining the selection by the selection means so as to select the output of the first video decoding means until a new channel switching instruction is received from the user And in response to receiving a new channel switching instruction from the user, the second video decoding means of the plurality of video decoding means is included in the digital broadcast signal of the channel indicated by the channel switching instruction. Select to select the output of the second video decoding means in response to the step of starting decoding of the video signal and the fact that the second video decoding means can output a normal video signal. Changing the selection by means.

  In this digital broadcast receiving apparatus, each of the plurality of video decoding means decodes a video signal included in a digital broadcast signal of a designated channel. The selection means selects the video signal output from the video decoding means designated by the preceding selection signal and outputs it to the display unit until a selection signal is given from the user. When a channel switching instruction is received from the user, the first video decoding unit is caused to start decoding the video signal of the channel instructed by the channel switching instruction. However, during this time as well, the selection signal selects and outputs the output of the video decoding means selected before the channel switching instruction. When the first video decoding unit can output a normal video signal, the selection unit is controlled to select the output of the first video decoding unit.

  According to this invention, when the user gives a channel switching instruction, the first video decoding means starts decoding the video signal of that channel. With a digital broadcast signal, normal video signal output by the first video decoding means is not immediately possible. However, until then, the selection means outputs the video signal of the channel designated by the previous selection signal to the display unit. Therefore, the screen displayed on the display unit during this time can be prevented from being completely dark. As a result, it is possible to prevent the user from misunderstanding that the screen is dark after the channel switching operation and the apparatus has failed. When the normal video signal can be output by the first video decoding means, the selection means is controlled to select the output. As a result, the video signal of the new channel decoded by the first video decoding means is displayed only when the normal video signal can be output. Until this video signal is displayed, the video of the channel before switching is displayed, so that the user dissatisfaction caused by not being given any information along with the channel switching can be alleviated.

  A computer program according to a third aspect of the present invention designates any one of a plurality of video decoding means for decoding a video signal included in a digital broadcast signal of a designated channel and a plurality of video decoding means. In response to the selection signal, the video signal output from the video decoding means designated by the selection signal is selected from the video signals output from the plurality of video decoding means and output to the display unit, and the next selection signal is given. A digital broadcast receiving apparatus including a selection means for maintaining selection by a preceding selection signal and a plurality of video decoding means and a computer for controlling the selection means until executed by the computer, It is a computer program for implement | achieving the control apparatus for changing. In response to receiving a channel switching instruction from the user, the computer program sends a digital broadcast signal of a channel indicated by the channel switching instruction to the first video decoding means among the plurality of video decoding means. In response to receiving a new channel switching instruction from the user, and a channel switching instruction to the second video decoding means among the plurality of video decoding means. In response to the means for starting decoding of the video signal included in the digital broadcast signal of the channel indicated by the second video decoding means can output a normal video signal, It functions as means for changing the selection by the selection means so as to select the output of the second video decoding means.

  According to the present invention, each of the plurality of video decoding means decodes the video signal included in the digital broadcast signal of the designated channel. The selection means selects the video signal output from the video decoding means designated by the preceding selection signal and outputs it to the display unit until a selection signal is given from the user. When receiving the channel switching instruction from the user, the starting means causes the first video decoding means to start decoding the video signal included in the digital broadcast signal of the channel instructed by the channel switching instruction. However, during this time as well, the selection signal selects and outputs the output of the video decoding means selected before the channel switching instruction. The changing means controls the selection means to select the output of the first video decoding means when the first video decoding means can output a normal video signal.

  When the user gives a channel switching instruction, the first video decoding means starts decoding the video signal of that channel. The normal video signal cannot be output immediately by the first video decoding means for the digital broadcast signal. However, until then, the selection means outputs the video signal of the channel designated by the previous selection signal to the display unit. Therefore, the screen displayed on the display unit during this time can be prevented from being completely dark. As a result, it is possible to prevent the user from misunderstanding that the screen is dark after the channel switching operation and the apparatus has failed. When the normal video signal can be output by the first video decoding means, the control means controls the selection means to select the output. As a result, the video signal of the new channel decoded by the first video decoding means is displayed only when the normal video signal can be output. Until this video signal is displayed, the video of the channel before switching is displayed, so that the user dissatisfaction caused by not being given any information along with the channel switching can be alleviated.

  As described above, according to the present invention, when the user gives a channel switching instruction, the first video decoding means specifies the previous video signal until the normal video signal can be decoded. The video signal of the selected channel is output to the display unit. Therefore, the screen displayed on the display unit during this time can be prevented from being completely dark. The video signal of a new channel is displayed for the first time when a normal video signal can be output. Until then, the video of the channel before switching is displayed. As a result, user dissatisfaction caused by not being given any information along with channel switching can be alleviated.

  In addition, since the video is processed, it is understood that the channel switching process is being performed, and there is an effect that the possibility of being mistaken as a failure is reduced.

  Hereinafter, a digital television broadcast receiver according to an embodiment of the present invention will be described. In the following description and drawings, the same reference numerals and names are assigned to the same components. Their functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 shows the relationship between a channel switching operation according to the prior art and a video display sequence 20. Referring to FIG. 1, it is assumed that the user is first viewing the first channel (CH1) and video 30 is displayed. It is assumed that the user selects the second channel (CH2) for the tuner at a certain timing. In the case of analog television broadcasting, the video 34 of the second channel is immediately displayed on the screen in response to this operation. However, in the case of digital television broadcasting, the video 34 of the second channel is not displayed immediately after the channel is switched, and the screen 32 that is completely dark is displayed for a certain period of time. This period is a period of time from when the video signal of the second channel is received and normal decoding (decoding) is started as described above. The encoding method of the broadcast digital broadcast signal and the channel switching instruction The length varies mainly depending on the timing.

[First Embodiment]
FIG. 2 shows a display video sequence 50 at the time of channel switching in the digital television broadcast receiving apparatus according to the first embodiment of the present invention described below. In the first embodiment, as will be described later, two tuners, a first tuner and a second tuner, are used. It is assumed that the user is watching the video 60 of the first channel first. This video is received and decoded by the first tuner. It is assumed that the user gives an instruction to switch the channel to the second channel at a certain timing. In this case, a period until the video 64 is displayed after the decoding of the signal of the second channel is basically the same as the conventional case shown in FIG. However, in the present embodiment, reception and decoding of the digital broadcast signal by the first tuner is continued according to the period 80 from when the channel switching instruction is given until the video 64 is displayed, as shown in FIG. The feature is that the video 62 of the channel before the channel switching (first channel) is continuously displayed instead of displaying the completely dark screen sequence 32. Further, in the present embodiment, in order to clarify that the channel switching operation is being performed, the display of the first channel image is performed by the image 62 until the display of the second channel image 64 is started. As shown, it is characterized in that it is performed while processing so that it is gradually reduced. Accordingly, since the first channel image can be viewed until the second channel image is displayed, there is an effect that the user does not feel a wasteful waiting time until the image display. Further, since the video is processed and displayed in a mode different from the normal video display, the user can easily understand that the channel is being switched. Therefore, there is an effect that the possibility of causing a misunderstanding that the apparatus has failed is reduced.

<Constitution>
FIG. 3 is a block diagram showing the configuration of the digital television broadcast receiver 90 according to the first embodiment of the present invention. Referring to FIG. 3, this digital television broadcast receiver 90 is used by being connected to a display 92 composed of a liquid crystal display (LCD) and an amplifier 94 for a speaker 96 for converting an audio signal into audio. It is.

  The digital television broadcast receiver 90 is connected to receive a digital television broadcast signal received by an antenna (not shown), and selects a digital broadcast signal of a channel designated by a channel selection signal given from the outside. First and second digital broadcast front-end processing unit tuners 100 and 102 (hereinafter referred to as “tuner 100” and “tuner 102”, respectively) for output and connected to receive the output of the tuner 100 are given. The digital broadcast signal is decoded, and the decoder 104 for outputting the video signal together with the audio signal frame by frame and the tuner 102 are connected to receive the output. Is output together with the audio signal frame by frame The decoder 106 has first and second inputs connected to the outputs of the decoders 104 and 106, respectively. For one of the first and second inputs, a designated input signal is shown in FIG. And a digital signal processor (DSP) 114 programmed to perform a reduction display such as the video 62 to be output.

  The digital television broadcast receiver 90 further includes three inputs that respectively receive the output of the decoder 104, the output of the decoder 106, and the output of the DSP 114, and any one of these three inputs is selected according to a given selection signal. A switching circuit 118 for selecting and outputting, a VRAM (video random access memory) 116 for storing a video signal output from the switching circuit 118 and supplying the video signal to the display 92, tuners 100 and 102, and decoder 104 2 and 106, the DSP 114, and the switching circuit 118, a CPU 110 for executing a predetermined program for executing video display at the time of channel switching as shown in FIG. 2, and an infrared ray for channel selection instruction from a remote controller (not shown) The signal is received and the channel switching code is sent to the CPU 110. An infrared light receiving portion 108 for providing a program and CPU110 which CPU110 is executed and a memory 112 for storing work variables and the like used in the program execution.

  The DSP 114 is programmed in advance, and the video signal given from one of the first input and the second input designated from the outside is selected according to the elapsed time from the time when the channel switching signal is received. It has a function of reducing and giving to the switching circuit 118. After receiving the switching signal, the switching circuit 118 has a function of maintaining the selection of the input designated by the immediately preceding received signal until the next switching signal is received.

  FIG. 4 is a flowchart of the channel main control program executed by the CPU 110 shown in FIG. 3, the channel selection program executed by the tuners 100 and 102, and communication between them.

  Referring to FIG. 4, the program for channel main control executed by CPU 110 waits until channel switching code is received from infrared light receiving unit 108 shown in FIG. 3, and the channel switching code is received in step 140. It is executed in response to the determination that it has been performed, and it is determined whether or not a channel switching instruction should be given to the tuner 100 or 102, and if necessary, the designated channel for either of the tuners 100 and 102 is determined. Step 142 for transmitting a channel switching instruction to select a channel, and a process executed after Step 142 and determining whether or not input switching by the switching circuit 118 shown in FIG. If necessary, go to subsequent steps, otherwise go to step 140 And a step 144 for diverting the sense.

  The channel main control program is further executed in response to the determination that there is switching by the switching circuit 118 in step 144, and determines whether or not the reduced display of the video signal by the DSP 114 shown in FIG. In response to step 146 for branching the process according to the result, and in response to the determination that DSP 114 is used in step 146, the currently received channel of decoders 104 and 106 is decoded for DSP 114. 2 is executed after step 148 and a step 148 to output a screen switching instruction so as to give the switching circuit 118 a reduction process as shown in FIG. And a decoder that outputs the video signal processed by the DSP 114 after the Executed in response to determining that the DSP 114 is not used in Step 150 and Step 150 in which the switch switching process for switching the input of the switching circuit 118 to the output of a different decoder is started, and then the process returns to Step 140. And step 152 for controlling the switching circuit 118 to switch to the input from the decoder corresponding to the newly selected channel. After step 152, control returns to step 140.

  When this program is executed, the CPU 110 controls the switching circuit 118 so as to select the output of the decoder 104 immediately after the power is turned on.

  The processes executed by the tuners 100 and 102 are the same as each other. Hereinafter, a program executed by the first tuner 100 will be described.

  The program executed by the first tuner 100 is executed after step 180 for setting the receiving channel to the default channel after power-on and after step 180, and whether a channel switching instruction is received from the channel main control program. Step 182 for branching control according to the determination result, and in response to the determination that the channel switching instruction has been received in Step 182, are executed according to the channel switching instruction given from the CPU 110. Step 184 for selecting the signal of the designated channel, and after step 184 or in response to the determination that there has been no channel switching instruction in step 182, receive the video signal of the set channel. , Return control to step 182 Tsu and a flop 186.

  The program executed by the second tuner 102 also has steps 200, 202, 204, and 206 that correspond to steps 180, 182, 184, and 186, respectively. Therefore, detailed description thereof will not be repeated.

  If it is determined in step 142 of the channel main control program that a channel switching instruction is to be given to the first tuner 100, a channel switching instruction is given to the first tuner 100, and the determination result in step 182 is determined. Is YES. Similarly, if it is determined in step 142 to give a channel switching instruction to the tuner 102, the determination result in step 202 is YES.

  FIG. 5 is a flowchart showing details of step 142 in FIG. Referring to FIG. 5, the process executed in step 142 of FIG. 4 determines whether or not first tuner 100 is receiving the channel indicated by the channel switching code received in step 140, and the determination result In step 220 for branching control according to the above, the control is executed in response to the determination that the first tuner is receiving the instruction channel in step 220, and the switching circuit 118 shown in FIG. Whether or not the output of the first tuner 100 is being displayed, step 222 for branching control according to the determination result, and determination that the output of the first tuner 100 is being displayed in step 222 A step 224 that is executed in response to the determination to continue displaying the output of the first tuner 100; Step 226 is executed in response to determining that the output of the first tuner 100 is not being displayed in step 222, and switches the switching circuit 118 to select the output of the first tuner 100. Including. After steps 224 and 226, the process of step 142 ends.

  Step 142 is further executed in response to determining in step 220 that the first tuner 100 is not receiving the channel indicated by the channel switching code, and the channel indicated by the channel switching code is set to the second channel. It is determined whether or not the second tuner 102 is receiving, and in step 228, the control is branched according to the determination result, and in step 228, it is determined that the second tuner 102 is receiving the indicated channel. And step 230 for determining whether the switching circuit 118 has selected the output of the second tuner 102 and branching the control in response to the determination result, and the second tuner in step 230. 102 is executed in response to the determination that the switching circuit 118 has selected the output of 102, and the second output Step 232 for deciding to continue displaying the output of the tuner 102, and in response to the determination that the switching circuit 118 is not displaying the output of the second tuner in Step 232, is executed. And step 234 for performing a process of switching the input to the display of the output of the second tuner 102 (the output of the decoder 106). After steps 232 and 234, step 142 ends.

  The processing performed in step 142 is further performed in response to determining in step 228 that the second tuner 102 is not receiving the indicated channel and selecting the output of the first tuner 100. Whether or not the switching circuit 118 is set, and the control branches in accordance with the determination result. In step 236, the output of the first tuner 100 (the output of the first decoder 104) is selected. In response to determining that the switching circuit 118 has been set, the designated channel is displayed while reducing the video signal written to the frame memory of the first decoder 104 as needed. A DSP 114 and a switching circuit 11 are provided so that a channel selection signal is given to the second tuner 102 so as to select and the display is switched to the output display. In step 238 and step 236, the switching circuit 118 is executed in response to the determination that the output of the first decoder 104 is not being displayed. The DSP 114 and the switching circuit 118 are provided so as to give a channel selection signal to the first decoder 104 so as to select the designated channel while reducing the video signal written to the frame memory and to switch to the display of the output. Determining 240 to control. After steps 238 and 240, step 142 ends.

  In steps 224, 226, 232, 234, 238, and 240, information for determination in steps 144 and 146 shown in FIG. 4 and switch switching and DSP screen reduction in steps 148, 150, and 152 are shown. In the display, a process is performed in which information for determining which decoder output is switched to which decoder output is generated.

  FIG. 6 is a flowchart of the switch switching process activated in step 150 of FIG. Referring to FIG. 6, this program is executed after step 250 and step 250 for switching the input of switching circuit 118 shown in FIG. 3 to select the output of DSP 114. In step 142 of FIG. It is determined whether or not a complete video for one frame has been created in the frame memory of the decoder that is determined to select and decode the subsequent channel, and this determination is repeated until a video for one frame is created. In step 252 and step 252, this is executed in response to determining that one frame of video has been completely created and written in the frame memory of the channel decoder after channel selection, and corresponds to the channel selected And a step 254 of controlling the switching circuit 118 to select the output of the decoder. After step 254, the process ends.

  In the process shown in FIG. 6, a signal for designating which decoder to switch the output from which decoder is given to this process. In steps 252 and 254, this information is used to check the frame memory of one of the decoders 104 and 106 shown in FIG. 3, and if it is found that a complete image for one frame has been prepared in the frame memory, The switching circuit 118 is controlled so as to select the output of the decoder.

<Operation>
The digital broadcast receiving apparatus 90 whose configuration has been described above operates as follows. Referring to FIG. 3, when the digital television broadcast receiver 90 is turned on, the first tuner 100 and the second tuner 102 are initialized and start receiving signals of channels that are initialized. . These signals are provided to decoders 104 and 106. On the other hand, the CPU 110 starts executing the program stored in the memory 112. In the present embodiment, CPU 110 controls switching circuit 118 to select the output of decoder 104 immediately after power-on.

  The decoder 104 decodes the encoded digital broadcast signal output from the first tuner 100 and supplies the signal to the switching circuit 118 via a frame memory (not shown). Similarly, the decoder 106 decodes the encoded digital video signal output from the second tuner 102 and supplies the output to the switching circuit 118 via the frame memory. The switching circuit 118 selects the output of the decoder 104 and supplies it to the VRAM 116 under the control of the CPU 110. The audio signal is given to the amplifier 94. The display 92 reads and displays the video signal of each frame written in the VRAM 116 at a predetermined time interval. The audio signal given to the amplifier 94 is amplified by the amplifier 94 and given to the speaker 96.

  It is assumed that the user has operated a remote controller (not shown) so as to change from the channel selected by the first tuner 100 to another channel. The remote controller outputs infrared rays indicating this channel switching instruction. The infrared light receiving unit 108 shown in FIG. 3 receives this infrared light, and gives a channel switching code for instructing switching to a designated channel to the CPU 110.

  Hereinafter, operations of the CPU 110 and the tuners 100 and 102 will be described with reference to FIG. When the channel switching code is received, the determination result of step 140 in FIG. 4 is YES. As a result, the process of step 142 is executed.

  Referring to FIG. 5, in step 220, it is determined whether or not the first tuner 100 is receiving a channel designated by the user. Here, it is assumed that the channel specified by the user is a channel different from the channel received by the first tuner 100. As a result, the determination result at step 220 is NO, and control proceeds to step 228. In step 228, it is determined whether or not the second tuner 102 is receiving the channel designated by the user. If the second tuner 102 is receiving the instructed channel, the video signal of this channel is output from the decoder 106 shown in FIG. In this case, in step 230, it is determined in step 230 whether or not the switching circuit 118 is set to select the output of the second decoder 106. If the display is being performed, the switching circuit 118 does not need to be operated, and reception and display of each tuner may be continued as they are. Therefore, in step 232, it is determined to continue displaying the second tuner output. That is, here, it is determined that the reception channels of the first and second tuners 100 and 102 are not changed and the switching circuit 118 is not changed. Thereafter, the processing is finished.

  On the other hand, if it is not determined in step 230 that the switching circuit 118 has selected the output of the second decoder 106, the process of step 234 is executed. In step 234, the switching circuit 118 is switched so as to select the output of the second decoder 106. As already described, the tuner 102 is receiving this channel, and the video signal of the channel being received is supplied from the decoder 106 to the switching circuit 118. Therefore, by switching the switching circuit 118 in step 234 and selecting the output of the decoder 106, the video decoded by the decoder 106 is written in the VRAM 116 and displayed on the display 90. However, in step 234, it is determined not to actually switch the switching circuit 118 but to switch the switching circuit 118 and select the output of the decoder 106. The actual switching is performed at step 152 shown in FIG.

  On the other hand, if it is determined in step 228 that the second tuner 102 is not receiving the instruction channel, the process of step 236 is executed. In step 236, the switching circuit 118 determines whether or not the output of the first tuner 100 is being displayed. If it is determined that the output of the first tuner 100 (the output of the decoder 104) is being displayed, the process of step 238 is executed. Otherwise, the process of step 240 is executed.

  In step 238, a channel selection signal is given to the second tuner 102 so as to select a signal of the designated channel. Further, after the video output from the decoder 104 is displayed while being reduced at a reduction ratio corresponding to the elapsed time since the channel instruction was switched, the DSP 114 and the switching circuit 118 are controlled so as to switch to the output of the decoder 106. It is decided. Similarly, in step 240, a channel selection signal is given to the first tuner 100 so as to select a signal of the designated channel. Further, the DSP 114 is configured so that the video signal output from the second decoder 106 is displayed while being reduced at a reduction ratio corresponding to the elapsed time since the instruction to switch the channel and then switched to the output display of the decoder 104. And decides to control the switching circuit 118.

  As described above, in steps 224, 226, 232, 234, 238, and 240, information on how to control the DSP 114 and the switching circuit 118 is determined, and then the processing in step 142 is terminated.

  Referring to FIG. 4, in step 144, it is determined whether or not there is output switching using switching circuit 118. For example, when any one of steps 226, 234, 238, and 240 shown in FIG. 5 has been executed, the determination result in step 144 is YES. In other cases, that is, when any one of steps 224 and 232 shown in FIG. 5 is performed, the determination result here is NO and control returns to step 140. In this case, the state of the DSP 114 and the switching circuit 118 does not change, and the video of the channel displayed on the display 92 does not change.

  Subsequently, in step 146, it is determined whether or not the DSP 114 is used. When one of the processes in steps 238 and 240 shown in FIG. 5 is executed, the DSP 114 is used. Therefore, in this case, the determination result is YES, and control proceeds to step 148. If any of steps 226 and 234 shown in FIG. 5 is executed, the determination result in step 146 is NO and control proceeds to step 152.

  In step 148, the DSP 114 is instructed to start a program for starting video reduction display, along with information on which input the video signal is switched from to which input. In response to this, the DSP 114 processes the video signal so that the video signal given from the designated input is reduced and displayed at a reduction ratio corresponding to the elapsed time from the time when the switching instruction is given, and Start the giving process. Subsequently, in step 150, processing for starting the switching process of the switching circuit 118 is performed in the CPU 110.

  Referring to FIG. 6, in step 250, processing for switching the input of switching circuit 118 to the output of DSP 114 is executed. As a result, the video that realizes the reduced display such as the video signal 62 shown in FIG. 2 output from the DSP 114 is written in the VRAM 116 and displayed on the display 92.

  In step 252, a process is performed to determine whether or not one frame of video has been prepared in the frame memory in the channel decoder (decoder 106 in this example) after channel selection. This determination is repeated until an image for one frame is produced. If one frame of video is prepared, the process proceeds to step 254. In step 254, the switching circuit 118 is controlled to switch the input from the output of the DSP 114 to the output of the decoder 106. As a result, the output of the decoder 106 is output from the switching circuit 118 and written into the VRAM 116. Therefore, the video of the channel selected by the second tuner 102 is displayed on the display 92.

  As described above, according to the digital television broadcast receiving apparatus 90 according to the present embodiment, when the user gives an instruction to switch from the currently displayed channel to another channel, the video signal of the switching destination channel can be displayed. Until that time, the video of the channel before switching is displayed. As a result, although the decoding takes time, the screen is not completely darkened, and the video of the channel before switching can be viewed during that time. As a result, the user is less likely to panic that the device has failed, and the user can see the video of the channel before switching until decoding is possible, and the user cannot see the video at all. Can be resolved. Further, during such channel switching, the video signal before switching is not displayed as it is, but gradually reduced and displayed. Therefore, the user can know that channel switching is in progress. For this reason, the user is less likely to misunderstand that the channel switching is not performed despite the channel switching instruction.

  As described above, according to the present embodiment, even when the channel is switched, until the user panics due to a misunderstanding that the device has failed, or until the display of the video after the channel switching becomes possible, The user is not wasted time. As a result, it is possible to alleviate user dissatisfaction when switching channels for digital broadcasting.

[Modification]
In the embodiment described above, at the time of channel switching, the video of the channel before switching is gradually reduced and displayed until video display of the channel after switching becomes possible. However, the present invention is not limited to such an embodiment. After the channel switching instruction until the video display of the channel after switching becomes possible, if the video signal before switching is processed and displayed in some form, the video can be processed in any way Good. For example, FIG. 7 shows such an example. In the video sequence 260 shown in FIG. 7, during the period 290 in which the video display after switching is possible when switching from the video display 270 of the reception channel by the first tuner to the video display 274 by the second tuner. As shown by the sequence 272, the image of the channel before switching is displayed after being processed so as to gradually thin (lower the contrast). By displaying in this way, the same effect as in the first embodiment can be obtained. In addition to this, various processes such as gradually decreasing (or increasing) the luminance of the image and gradually thinning out the scanning lines can be performed. At the same time, as described in Patent Document 1, a message indicating that the channel is being switched may be displayed.

  The embodiment disclosed herein is merely an example, and the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by each of the claims after taking into account the description of the detailed description of the invention, and all modifications within the meaning and scope equivalent to the wording described therein are intended. Including.

It is a schematic diagram which shows the video sequence at the time of the channel switching by a prior art. It is a figure which shows typically the video sequence at the time of channel switching by the digital television broadcast receiver which concerns on the 1st Embodiment of this invention. It is a schematic block diagram of the digital television broadcast receiver 90 which concerns on 1st Embodiment. 3 is a flowchart showing a control structure of a channel main control program executed by a CPU 110 of the digital television broadcast receiving apparatus 90 and a program executed by the first and second tuners 100 and 102. It is a flowchart of the process performed by step 142 of the channel main control program shown in FIG. FIG. 5 is a flowchart showing a control structure of a program that is started in step 150 of FIG. 4 and that realizes a switching process of a switching circuit. It is a figure which shows typically the video sequence in the modification of 1st Embodiment.

Explanation of symbols

90 digital television broadcast receiver 100 first digital broadcast front-end processing unit tuner (first tuner)
102 Second digital broadcast front-end processing unit tuner (second tuner)
104, 106 Decoder 108 Infrared light receiving unit 110 CPU
112 memory 114 DSP
116 VRAM
118 switching circuit

Claims (4)

A plurality of video decoding means for receiving a digital broadcast signal and decoding a video signal included in the digital broadcast signal of the designated channel;
In response to a selection signal designating any one of the plurality of video decoding means, a video signal output from the video decoding means designated by the selection signal is selected from video signals output from the plurality of video decoding means. A selection means for selecting and outputting to the display unit and maintaining the selection by the preceding selection signal until the next selection signal is given;
In response to receiving the channel switching instruction from the user, the first video decoding means of the plurality of video decoding means receives the video signal included in the digital broadcast signal of the channel indicated by the channel switching instruction. In response to the fact that the first video decoding means can output a normal video signal by starting decoding, the selection means is selected to select the output of the first video decoding means. A digital broadcast receiving apparatus including control means for providing the selection signal. The control means includes
In response to receiving the channel switching instruction from the user, the first video decoding means of the plurality of video decoding means receives the video signal included in the digital broadcast signal of the channel indicated by the channel switching instruction. A channel selection signal output means for outputting a channel selection signal for starting decoding;
In response to the fact that the first video decoding means having received the channel selection signal can normally decode the video signal included in the digital broadcast signal of the channel indicated by the channel selection signal. Means for providing a selection signal to the selection means so as to select an output of the first video decoding means,
The selection means includes
In response to the channel selection signal, signal processing means for executing processing for performing predetermined processing on the video signal being selected and outputting;
It is connected to receive the outputs of the plurality of video decoding means and the output of the signal processing means. Until the channel selection signal or the selection signal is given, the output indicated by the preceding channel selection signal or selection signal is output. Selecting, selecting and outputting the output of the signal processing means in response to the channel selection signal, and selecting the output of the video decoding means specified by the selection signal in response to the selection signal The digital broadcast receiving apparatus according to claim 1, further comprising switching means for switching input / output. A plurality of video decoding means for receiving a digital broadcast signal and decoding a video signal included in the digital broadcast signal of the designated channel;
In response to a selection signal designating any one of the plurality of video decoding means, a video signal output from the video decoding means designated by the selection signal is selected from video signals output from the plurality of video decoding means. Digital broadcast reception for changing channel in digital broadcast receiving apparatus including selection means for selecting and outputting to display unit and maintaining selection by preceding selection signal until next selection signal is given An apparatus control method comprising:
In response to receiving the channel switching instruction from the user, the first video decoding means of the plurality of video decoding means receives the video signal included in the digital broadcast signal of the channel indicated by the channel switching instruction. Starting decryption;
Maintaining the selection by the selection means to select the output of the first video decoding means until receiving a new channel switching instruction from the user;
In response to receiving a new channel switching instruction from the user, the video included in the digital broadcast signal of the channel indicated by the channel switching instruction to the second video decoding means of the plurality of video decoding means Starting decoding of the signal;
In response to the fact that the second video decoding means can output a normal video signal, changing the selection by the selection means so as to select the output of the second video decoding means. A method for controlling a digital broadcast receiving apparatus. A plurality of video decoding means for receiving a digital broadcast signal and decoding a video signal included in the digital broadcast signal of the designated channel;
In response to a selection signal designating any one of the plurality of video decoding means, a video signal output from the video decoding means designated by the selection signal is selected from video signals output from the plurality of video decoding means. A selection means for selecting and outputting to the display unit and maintaining the selection by the preceding selection signal until the next selection signal is given;
A computer program for realizing a control device for changing a channel by being executed by the computer in a digital broadcast receiving device including a plurality of video decoding means and a computer for controlling the selection means And said computer
In response to receiving the channel switching instruction from the user, the first video decoding means of the plurality of video decoding means receives the video signal included in the digital broadcast signal of the channel indicated by the channel switching instruction. Means for initiating decryption;
In response to receiving a new channel switching instruction from the user, the video included in the digital broadcast signal of the channel indicated by the channel switching instruction to the second video decoding means of the plurality of video decoding means Means for initiating decoding of the signal;
In response to the fact that the second video decoding means can output a normal video signal, the selection by the selection means is changed so as to select the output of the second video decoding means. A computer program that functions as a means of

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