# Patent

## Title
Television tuner for controlling directivity of an antenna

## Abstract

Disclosed is a television tuner for receiving television broadcast signals with a smart antenna, which is equipped with an auto-scan unit that causes a channel storing section to automatically stores a receiving channel and the corresponding receiving direction at the time when the signal condition from a tuner section matches the predetermined signal condition matches the predetermined signal condition. The auto-scan unit causes a directivity control section to perform a variable directivity control for every direction and to detect the signal condition for each direction, and switches the receiving channel in the tuner section when a receiving direction is stored. This improves the convenience in adjusting the antenna directivity for each receiving channel.

## Background
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a television tuner that receives television broadcast signals with a smart antenna.
2. Description of the Prior Art
In television broadcasting, transmitter location may differ with each broadcasting station. In such a case, to receive the radio wave from a desired station, it is necessary to set up the receiver to receive the desired channel and also to adjust the directivity of the antenna toward the transmitter of the desired station.
Conventionally, an antenna switching device is known that is capable of automatically setting the directivity of an antenna to the transmitter of a desired receiving channel according to the selection of the desired receiving channel by a remote control (refer to Japanese Patent Laid-Open No. 2001-168627, for example).
To automatically set the directivity of the antenna as described above, it is necessary to pre-store a receiving channel at which broadcast signals are optimally received, together with the corresponding directivity of the antenna at the time. However, the antenna switching device described in the JP-A No. 2001-168627 has a problem that the antenna directivity adjustment must be made manually (such as by the operation of a remote control) by the user for every receiving channel, thus taking much time.
SUMMARY OF THE INVENTION
The present invention addresses the above problem and aims to provide a television tuner that allows easy adjustment of the antenna directivity for each receiving channel.
To achieve the above object, one aspect of the present invention is directed to a television tuner that receives television broadcast signals with a smart antenna capable of statically selecting the directivity by means of electric signals, including:

    a directivity control section that outputs an electric signal to select the directivity of the smart antenna;
    a tuner section that receives television broadcast signals in the predetermined band with the smart antenna;
    a signal condition detector section that detects the signal condition of a signal from the tuner section by detecting the AGC voltage specifying the gain of a signal from the tuner and/or the bit error rate of a digital signal from the tuner section;
    and a channel storing section that stores the receiving channel and the receiving direction of the smart antenna when the signal condition of a signal detected by the signal condition detector section matches the predetermined signal condition, by making them corresponding to each other,

wherein:

    an auto-scan unit is provided that causes the channel storing section to automatically store a plurality of receiving channels; and
    the auto-scan unit is designed such that the variable directivity control of the smart antenna for each direction is performed by the directivity control section, the detection of the signal condition is done by the signal condition detector section, and the receiving channel of the tuner section is switched when a receiving channel is stored in the channel storing section.


In the aspect configured as above, the signal condition detector section detects the signal condition of a signal extracted by the tuner section. The channel storing section stores the receiving channel and the receiving direction of the smart antenna when the signal condition of a signal detected by the signal condition detector section matches the predetermined signal condition, by making them corresponding to each other. The auto-scan unit causes the channel storing section to automatically store a plurality of receiving channels.
The auto-scan unit preferably changes the directivity of the smart antenna to every direction, causes the signal condition detector section to detect the signal condition for each direction, and switches the receiving channel in the tuner section when a receiving channel is stored in the channel storing section. That is, the detection of the signal condition is automatically made for each direction, and the switching of the receiving channel is also made automatically. This makes it possible to automatically store a receiving channel with good signal condition from the tuner section for every receiving channel, thus eliminating the need for the directivity adjustment operations for the smart antenna and the need for the receiving channel switching operations. As a result, the convenience in antenna directivity setting for each receiving channel is improved.
Also, the auto-scan unit switches the receiving channel in the tuner section when the channel storing section has stored a receiving channel. That is, the auto-scan unit causes the signal condition detector section to detect the signal condition in each direction for one receiving channel, and when the detected signal condition matches the predetermined signal condition, stops the detection of the signal condition for that receiving channel and switches to the next receiving channel. This makes it possible to increase the speed of the antenna directivity adjustment for each receiving channel.
Another aspect of the present invention is directed to a television tuner that receives television broadcast signals with a smart antenna capable of statically selecting the directivity, including:

    a directivity control section that outputs an electric signal to select the directivity of the smart antenna;
    a tuner section that receives television broadcast signals in the predetermined band with the smart antenna;
    a signal condition detector section that detects the signal condition of a signal output from the tuner section; and
    a channel storing section that stores the receiving channel and the receiving direction of the smart antenna, by making them correspond to each other, when the signal condition of a signal detected by the signal condition detector section matches the predetermined signal condition,

wherein:

    an auto-scan unit is provided that causes the channel storing section to automatically store a plurality of receiving channels; and
    the auto-scan unit is designed to causes the directivity control section to perform the variable directivity control of the smart antenna for each direction, causes the signal condition detector section to detect the signal condition, and switch the receiving channel in the tuner section as needed.


In the aspect configured as above, the signal condition detector section detects the signal condition of a signal extracted by the tuner section. The channel storing section stores the receiving channel and the receiving direction of the smart antenna, by making them correspond to each other, at the time when the signal condition of a signal detected by the signal condition detector section matches the predetermined signal condition. The auto-scan unit causes the channel storing section to automatically store a plurality of receiving channels.
The auto-scan unit preferably changes the directivity of the smart antenna to every direction, causes the signal condition detector section to detect the signal condition in every direction, and switches the receiving channel in the tuner section. That is, the detection of the signal condition is automatically made for each direction, and the switching of receiving channel is also made automatically. This makes it possible to automatically store a receiving channel with good signal condition from the tuner section for each receiving channel, thus eliminating the need for the directivity adjustment operations for the smart antenna and the need for the receiving channel switching operations. As a result, the convenience in antenna directivity setting for each receiving channel is improved.
In the aspect of the present invention, the auto-scan unit may be designed to switch the receiving channel when a receiving channel is stored in the channel storing section.
In this configuration, the auto-scan unit switches the receiving channel in the tuner section when the channel storing section has stored a receiving channel. That is, the auto-scan unit causes the signal condition detector section to detect the signal condition in each direction for a receiving channel, and when the detected signal condition matches the predetermined signal condition, stops the detection of the signal condition for that receiving channel and switches to the next receiving channel. This makes it possible to increase the speed of the antenna directivity adjustment for each receiving channel.
In the aspect of the present invention, the signal condition detector section may be an AGC circuit that detects AGC voltage specifying the gain of a signal from the tuner section.
This embodiment makes it possible to store a receiving direction in which the signal condition of the intermediate frequency from the tuner section is good.
In the aspect of the present invention, the signal condition detector section may be a demodulator circuit that detects the bit error rate of a digital signal from the tuner section.
This configuration makes it possible to store a receiving direction in which the bit error rate of a signal from the tuner section is low.
Furthermore, a television may have the sections and units of the television tuner of the present invention. That is, the present invention may be applied to a television with a tuner function.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the configuration of a television receiving system;
FIG. 2 is a block diagram showing the internal configuration of a smart antenna unit;
FIG. 3 is a block diagram showing the internal configuration of a television tuner;
FIG. 4 is conceptual diagram illustrating the smart antenna unit;
FIG. 5 shows an example of channel selection data;
FIG. 6 is a flowchart showing a main processing;
FIG. 7 is a flowchart showing an auto-scan processing that is invoked and executed at step S140 of the flowchart shown in FIG. 6; and
FIG. 8 is a flowchart showing another example of the auto-scan processing.



DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows the basic configuration of a television receiving system equipped with a television tuner according to the present invention. In the figure, a television 30 and a rough rectangular box-shaped television tuner 20 connected to the television 30 with a not shown cable are shown. The television tuner 20 is a so-called set-top box and can be placed at any location if connectable to the television 30. Connected to the television tuner 20 is an antenna cable 16, through which the television tuner 20 is connected to a smart antenna unit 10.
The smart antenna unit 10 has a foot 17 at the bottom for stable installation, and a roughly column-shaped leg 18 standing almost vertically on the foot 17. At the top of the leg 18, a roughly square-shaped (seen from top) plate-like antenna holder 19 is mounted. The antenna holder 19 is to be almost horizontal and four rod-like directional antennae 11 are projecting outward radially from the side. Since the angle formed by adjacent directional antennae 11 is to be 90 degrees, the directional antennae 11 are disposed with even spacing from each other around the circumference of the antenna holder 19. Furthermore, each of the directional antennae 11 is extendable and the user can extend them as needed. It is possible to control the directivity of the smart antenna unit 10 omnidirectionaly by changing the predetermined phase of radio waves received by these directional antennae 11. This configuration enables adjusting the directivity of the antenna to any direction from which terrestrial television airwave is transmitted to the smart antenna unit 10. This makes it possible for the user to receive more broadcast channels and enjoy more television programs.
FIG. 2 schematically shows the internal configuration of the smart antenna unit 10. In this figure, the four directional antennae 11 are connected to four phase shifters 12 respectively with separate wires. The phase shifter 12 is a circuit that can control the phase shift amount of a signal input from the directional antenna 11, and can delay the phase according to the bias voltage output from the television tuner 20. The signal whose phase shift amount has been controlled by each phase shifter 12 is input to a compositor 14 to be composed therein. The signal composed by the compositor 14 is input to a booster circuit 13 to be amplified.
Thus, varying and composing the phase of a signal that has been input from each of the four directional antennae 11 enables the four directional antennae 11 to have the directivity for any direction including their axial directions. That is, by setting the phase shift amount of each phase shifter to an appropriate value, it is possible to set the direction of the main beam formed by the smart antenna unit 10 to any direction.
FIG. 3 schematically shows the internal configuration of the television tuner 20. In the figure, the television tuner 20 includes an antenna control section 21 that controls the phase shift amount by the phase shifter 12 in the smart antenna unit 10, and a tuner section 22 that inputs frequency signals from the smart antenna unit 10. The television tuner 20 generates a signal to control the directivity of the antenna of the smart antenna unit 10 according to a command from a CPU 28a. Specifically, the receiving direction of the smart antenna unit 10 is varied by varying the bias voltage to be output to each phase shifter 12. The television tuner 20 contains a ROM (not shown) to store the combination of bias voltages to be output to each phase shifter 12. Sixteen- (16) patterns of the bias voltage combination are stored, and the television tuner 20 outputs one of these patterns to each phase shifter 12 according to the command from the CPU 28a. 
This configuration enables the smart antenna unit 10 to realize 16 receiving directions. FIG. 4 shows these 16 receiving directions. As can be seen, it is possible to set evenly spaced 16 receiving directions radiating from the antenna holder 19. That is, the angle difference between any adjacent receiving directions is 360/16=22.5 degrees. Thus, by setting the evenly spaced receiving directions radiating from the antenna holder 19, it is possible to set the directivity to any direction from which airwave arrives. The receiving direction “D” is defined to identify the direction at the top of the figure as D=0, the next direction clockwise as D=1, the next as D=2, the next as D=3, and the last direction as D=15.
The tuner section 22 shown in FIG. 3 has a so-called synthesizer-type tuner configuration, and PLL data i.e. frequency division ratio data in a PLL loop is supplied to the tuner section 22 as the channel selection signal. Also, the tuner section 22 selects one receiving channel out of a plurality of receiving channels by extracting a frequency signal in the desired frequency band when the PLL data is received as the channel selection signal from the CPU 28a. The CPU 28a detects a frequency shift in the tuner section 22, and supplies an AFT voltage to the tuner section 22 based on the detection result. Then, the tuner section 22 corrects the frequency band to be extracted according to the AFT voltage for optimal channel selection.
The output of the tuner section 22 is supplied to either of a digital reproduction section 23 and an analog reproduction section 24. That is, the television tuner 20 according to the present embodiment allows reproduction of both digital broadcast signal and analog broadcast signal. The digital reproduction section 23 includes a digital I/F 23a, a demodulator circuit 23b, a descrambling section 23c, a demultiplexing section 23d, and an MPEG decoder 23g. The I/F 23a to which the frequency signal is input from the tuner section 22 is equipped with an A/D converter, and the demodulator section that receives the signal from the digital I/F 23a is provided with a channel equalizer, an error correction decode section, and the like.
In other words, the digital I/F 23a and the demodulator circuit 23b converts frequency signal to be input from the tuner section 22 into a digital signal, and also performs a so-called ghost cancellation for the digital-demodulated signal based on the control signal from the CPU 28a. Furthermore, the digital I/F 23a and the demodulator circuit 23b correct bit errors that occurred on the transmission path, to obtain the transport stream (TS) output. In this processing, the demodulator circuit 23b detects the ratio of the bit errors to the entire data as bit error rate.
The transport stream obtained by performing demodulation and error correction processing at the demodulator circuit 23b is fed to the descrambling section 23c. Since the transport stream is usually scrambled, it is impossible to reproduce pictures and sounds without descrambling. Therefore, the descrambling section 23c descrambles the transport stream to demodulate the transport stream to data array that can be reproduced. The descrambled transport stream has a format in which video and audio signal and text information are multiplexed, and therefore supplied to the demultiplexing section 23d, where the input data is demultiplexed. The descrambling section 23c and the demultiplexing section 23d can use the DRAM 23e as a work area when performing respective processing.
As the result of the demultiplexing process, the input data is divided into MPEG data in which video and audio signals are compressed in the predetermined method and data other than the video and audio signals, for example text information on TV programs, and the latter data is then provided to the CPU 28a. The former MPEG data is supplied to the MPEG decoder 23g, and is decompressed, i.e. MPEG-decoded, at the MPEG decoder 23g. By MPEG-decoding the MPEG data, digital video and digital audio signals are produced, and the produced digital video signal is further converted to the analog video signal.
The MPEG decoder 23g is equipped with an OSD processing section 23h which allows overlapping a predetermined still picture on the displayed picture or replacing with a predetermined still picture. The OSD processing section 23h can input the received text information data, etc. from the CPU 28a, and produce a still picture, etc. based on the text information data, etc.
The MPEG decoder can use the DRAM 23f as a work area when performing an MPEG-decoding or OSD processing. Thus, the MPEG decoder 23g can perform the decompression and it is possible to perform a graphics processing with the OSD processing section 23g. The video signal that has been decompressed and converted to the analog signal is fed to a video output section 26, and is output to the television 30 by the video output section 26. As a method of outputting analog video signals to the television 30, various methods can be employed including the composite output and the S-Video output.
Meanwhile, the audio signal generated by the MPEG decoding is input to a D/A converter section 25 and converted to the analog audio signal at the D/A converter section 25. This analog audio signal is input to an audio output section 27, and is output to the television 30 from the audio output section 27. However, if the television 30 has an optical input terminal or the like and accepts digital audio signals, it is possible to output a digital audio signal directly to the television 30 without converting it with the D/A converter section 25.
The analog reproduction section 24 includes an analog I/F 24a, the demodulator circuit 24b, an NTSC decoder 24d, and an audio decoder 24e. The analog I/F 24a and the demodulator circuit 24b are equipped with an AGC circuit 24b1 that amplifies an intermediate frequency (IF) signal input from the tuner section 22. The gain of the IF signal at the AGC circuit 24b1 is specified by an ACG voltage, and the AGC voltage varies with the amplitude level of the IF signal amplified by the AGC circuit 24b1. That is, the AGC circuit 24b1 amplifies the IF signal using an AGC voltage as the feedback signal.
Specifically, when the IF signal is strong, the AGC voltage is decreased to lower the gain, and when the IF signal is weak, the AGC voltage is increased to raise the gain. That is, in this embodiment, it can be said that the higher the AGC voltage the weaker the IF signal to be input from the tuner section 2. This enables the amplitude level of the amplified IF signal to be almost constant, thus preventing the difference in reproduced colors among different channels. Furthermore, since the AGC voltage is generated by comparing the amplified IF signal with a predetermined reference voltage, it is possible to maintain the amplitude level of the amplified IF signal at an ideal level. The AGC voltage is output to the CPU 28a, and based on the output AGC voltage, the CPU 28a executes various controls.
The demodulator circuit 24b generates analog video and audio signals in the NTSC format by separating the demodulated IF signals. The generated analog video signals are input to the NTSC decoder 24d, and converted to digital video signals in the CCIR656 format at the NTSC decoder 24d. The NTSC format is a standard format of analog television signals, and includes the signal for color reproduction, the 15.75 kHz horizontal sync signal, the 60 Hz vertical sync signal, etc. The demodulator circuit 24b contains a sync separator circuit 24c to extract the horizontal sync signal and vertical sync signal, and allows the NTSC decoder 24d to generate a synchronized digital video signal based on the horizontal sync signal and vertical sync signal extracted by the sync separator circuit 24c. Meanwhile, the CCIR656 format is a digital video signal format in which each element of the YUV is represented in digital graduation. The analog audio signal separated at the demodulator circuit 24b is supplied to the audio decoder 24e, and separated into right and left stereo audio signals at the audio decoder 24e. 
The digital video signal generated at the NTSC decoder 24d is input to the MPEG decoder 23g, and undergoes the OSD processing and the conversion to an analog signal. The converted analog video signal is then fed to the video output section 26, and output to the television 30 from the video output section 26. Meanwhile, the audio signal is input to the audio output section 27, and output to the television 30 from the audio output section 27.
The CPU 28a is connected to a bus 29, and executes the control processing to implement various function of the television tuner 20, using a RAM 28b connected to the bus 29 as a work area. The programs that executes this control processing are pre-stored in a ROM 28c, and the CPU 28a reads the predetermined program into the RAM 28b as needed to perform the control processing. Also, the bus 29 has a rewritable EEPROM 28d, and the CPU 28a uses various data stored in the EEPROM 28d to execute the control processing.
In the EEPROM 28d, as one example, channel selection data 28d1 is stored. FIG. 5 shows an example of the channel selection data 28d1. The channel selection data 28d1 is a table listing correspondingly the channel numbers of receiving channels that can be selected with a remote control 40 or the like, the frequency bands extracted by the tuner section 22, and the receiving direction patterns “D” in which signal condition is good, including the frequency band. It is possible to identify the frequency band and receiving direction corresponding to the channel number specified by the CPU 28a by referencing this table. In this embodiment, since the tuner section 22 employs the synthesizer method, the correspondence between the channel number and the frequency division data is stored as the channel selection data 28d1. Also, the receiving direction pattern “D” in which signal condition is good is stored as a combination pattern of the bias voltage output to each phase shifter 12 of the smart antenna unit 10.
Thus, by prestoring the channel selection data 28d1, it is possible to receive every channel with optimum condition even if different channels arrive from different directions. Here, receiving every channel with optimum condition means setting the receiving direction of the smart antenna 10 to the direction of the transmitter of the broadcaster corresponding to the channel number of a desired channel. This enables receiving strong broadcast signals, and makes it less likely to be interfered by noises from other directions.
If the channel selection data 28d1 is not stored in the EEPROM 28d, it is necessary to store the channel selection data 28d1 in the EEPROM 28d by inputting a command from the remote control or the like. When the command to store the channel selection data 28d1 is input, the auto-scan processing is performed to produce the channel selection data 28d1. In this auto-scan processing, the signal condition in every direction is automatically detected for one channel number, and also channel number is switched sequentially each time the detection for all directions is done. When a signal condition reaches the predetermined signal condition, the channel number is stored in the EEPROM 28d, together with the corresponding receiving direction pattern “D”. In contrast, if the detected signal condition does not reach the predetermined signal condition, the channel number is not stored. It is possible to perform the auto-scan processing automatically if the channel selection data 28d1 is not stored. Even when the channel selection data is stored, the channel selection data 28d1 may be updated by inputting a command from the remote control 40 or the like to perform the auto-scan processing.
Furthermore, the OSD data 28d2 for producing an OSD image at the OSD processing section 23h is stored in the EEPROM 28d. The CPU 28a reads the OSD data 28d2 as needed according to the command from the remote control 40 or the operation state of each circuit, and supplies the OSD data 28d2 to the OSD processing section 23h. For example, when the CPU 28a determines that it is necessary to issue a warning to the user, the warning screen reads the OSD data 28d2 that can be produced and instructs the OSD processing section 23h to incorporate the warning screen into the picture.
A remote control I/F 28e is connected to the bus 29, and it is possible to input an infrared blink signal to be output from the remote control 40 that is an external device. This infrared blink signal is sent to the CPU 28a via the bus 29, and the CPU 28a executes the corresponding control processing. To the bus 29, a bus I/F 28f for connecting to an external device through a cable, and an IC card I/F 28g for giving and receiving data to and from an IC card are also connected. The information read from the bus I/F 28f or the IC card I/F 28g is sent to the CPU 28a via the bus 29 and processed by the CPU 28a accordingly.
Now, the flow of the main processing to be executed by the television tuner 20 shown in FIGS. 1 and 3 will be described with reference to the flowchart shown in FIG. 6. First, an initialization is performed in step S100. Initialization includes, for example, the clearing of the RAM 28b, a register in the CPU 28a, and the reading of the setting data for white balance adjustment from the EEPROM 28d is performed.
In step S110, it is determined whether or not the channel selection data 28d1 is stored in the EEPROM 28d. If the channel selection data 28d1 is stored in the EEPROM 28d, a video signal control processing is performed in step S120. In this processing, the CPU 28a takes the initiative in controlling each section and each circuit constituting the television tuner 20, and performs the processing to display the television image corresponding to the channel number. Also, during this processing, if a command is issued from the remote control 40 to change a channel number, the PLL data corresponding to the channel number is provided to the tuner section 22 to change the receiving channel.
If the channel selection data 28d1 is not stored in the EEPROM 28d at step S110, menu selection is made with the remote control 40 in step S130 to check if an auto-scan start command is input. If the auto-scan start command is input, the auto-scan processing is performed at step S140. This auto-scan processing will be described in detail with reference to FIG. 7.
If it is determined that the auto-scan start command is not input at step S130, it is checked whether or not a command to turn off the television tuner 20 is input at step S150. If the command to turn off the television tuner 20 is not input, control is returned to step S120, and if the command is input the main processing is finished.
Now, with reference to FIG. 7, the flow of auto-scan processing is described that is invoked and executed at step S140 of the flowchart in FIG. 6. First, the channel number “α” is set to α=2 at step S200. Also, the processing to provide the tuner section 22 with PLL data corresponding to the set channel number is performed at step S200.
At step S210 the receiving direction pattern “D” is set to D=0, and at step S210 the bias voltage corresponding to the set receiving direction pattern (D=0) is supplied to each of the four phase shifters 12. This will set the directivity of the smart antenna 10.
Then, the processing for detecting signal condition is performed at step S220. If a frequency signal output from the tuner section 22 is a digital frequency signal, the signal condition is detected by detecting the bit error rate at the digital I/F 23a and the demodulator circuit 23b. If a frequency signal output from the tuner section 22 is an analog signal, the signal condition is detected from the AGC voltage output from the AGC circuit 24b1 to the CPU 28a. 
Next, it is determined whether or not the detected signal condition is the predetermined signal condition. The reference data for determining the signal condition (bit error rate and data on AGC voltage) is stored in the ROM 28 or the like contained in the television tuner 20, and the processing of step S230 determines the detected signal condition based on this data.
If the detected signal condition is the predetermined signal condition at step S230, the processing for storing the channel number and receiving direction pattern is performed. In this processing, the channel number set in the processing at step S200 or at step S280 described below, and the receiving direction patter “D” that is identified as the predetermined signal condition at step S230 are stored in the EEPROM 28d with them corresponding to each other.
If the signal condition detected at step S230 is not the predetermined signal condition, it is checked if the receiving direction pattern “D” is D<15. If D<15, the receiving direction pattern value is updated to D=D+1 at step S260 and then control is returned to step S220.
If D=15 (not D<15) at step S250, it is checked if the channel number “α” is α<69 at step S270. If aα<69, the channel number is updated to α=α+1 and control is returned to step S210. If α=69 (not (α<69), the auto-scan processing is finished.
Now, a specific example of the auto-scan processing shown in FIG. 7 is described with reference to FIG. 5. First, the channel number is set to (α=2 (step S200), and the receiving direction pattern is set to D=0 (step S210). Then, the signal condition at this receiving direction pattern is detected (step S220) and the detected signal condition is identified (step S230) As shown in FIG. 5, if the channel number is (α=2 the signal condition is good when the receiving direction pattern is D=1. In this case, it is determined that the detected signal condition is not the predetermined signal condition, and thus the storing of the subsequent channel numbers and receiving direction patterns will not be performed.
When the signal condition for the receiving direction pattern D=0 is detected and identified, the receiving direction pattern is set to D=1 (step S260), the detection of the signal condition is performed for this receiving direction pattern (steps S220). As described above, since signal condition is good at this receiving direction pattern, the channel number (α=2) and receiving direction pattern (D=1) is stored in the EEPROM 28d (step S240). After they are stored, the receiving direction pattern is incremented by one and the detection and identification of the signal condition is performed for this receiving direction pattern. When the detection and identification of the signal condition is performed at receiving direction pattern D=15, then the channel number is incremented by one and set to α=3 (step S280), and the receiving direction pattern is set within the range of D=0 to 15 for this channel number and the detection and identification of the signal condition is performed for each receiving direction pattern. Since there is no receiving direction pattern at which signal condition is good when the channel number is α=3, as shown in FIG. 5, this channel number and the corresponding receiving direction pattern is not stored.
Thus, the television tuner 20 detects the signal condition of the frequency signal from the tuner section while changing the receiving direction pattern within the range of D=0 to 15 with the channel number fixed, and when D=15 and the detection is completed for all the directions, the channel number is switched. Then, when the signal condition detected at one channel number matches the predetermined signal condition, that channel number and the corresponding receiving direction pattern are stored in the EEPROM 28d, and this procedure is performed for every channel number to produce the channel selection data 28d1.
Described with reference to FIG. 7 is the case where, regardless of whether the channel number when the detected signal condition matches the predetermined signal condition is stored in the EEPROM 28d, the receiving direction pattern is changed within the range of D=0 to 15 and the channel number is switched after the detection of the signal condition is done for all directions. However, the television tuner 20 may be implemented such that the switching of channel number is made when the receiving channel at which the detected signal condition matches the predetermined signal condition is stored in the EEPROM 28d. 
Now, another example of the main processing to be executed in the television tuner 20 is described with reference to the flowchart shown in FIG. 8. In FIG. 8, after the processing at step S240 is done, control goes to step S270. That is, when the channel number and the receiving direction pattern are stored in the EEPROM 28d, the subsequent receiving direction patterns are not changed and the channel number is switched. By doing this, it is possible to increase the speed of setting the antenna directivity for each channel number.
Next, a specific example of the auto-scan processing shown in FIG. 8 is described with reference to FIG. 5. First, the channel number is set to α=2 (step S200), and then the receiving direction pattern is set to D=0 (step S210). Then, the signal condition at this receiving direction pattern is detected (step S220) and the detected signal condition is identified (step S230) As shown in FIG. 5, for the channel number α=2, the signal condition is good when the receiving direction pattern is D=1. In this case, it is determined that the detected signal condition is not the predetermined signal condition, and thus subsequent channel numbers and receiving direction patterns will not be stored.
When the signal condition for the receiving direction pattern D=0 is detected and identified, then the receiving direction pattern is set to D=1 (step S260) and the detection and identification of signal condition is performed for this receiving direction pattern (step S220). As described above, since the signal condition is good at this receiving direction pattern, the channel number ((α=2) and the receiving direction pattern (D=1) are stored in the EEPROM 28d (step S240).
When they are stored, the subsequent receiving direction patterns (D=2 to 15) are not set, the channel number is incremented by one and set to α=3 (step S280), the receiving direction pattern is set within the range of D=0 to 15 for this channel number, and the detection and identification of the signal condition is performed for each receiving direction pattern. As shown in FIG. 5, since there is no receiving direction pattern at which signal condition is good for channel number α=3, this channel number and the corresponding receiving direction pattern are not stored. Thus, in the auto-scan processing shown in FIG. 8, when the detected signal condition matches the predetermined signal condition, the receiving direction pattern setting is not changed for that channel thereafter, and the next channel is examined.
As described above, according to the present invention it is possible to automatically store the receiving direction for each receiving channel, thus eliminating the need for adjustment and switching operations for the smart antenna and improving the convenience.

## Claims

1. A television tuner for control of directivity of an antenna, comprising:
a directivity control section that outputs an electric signal to select a directivity of the antenna, the directivity control section includes:
plurality of directional antennas coupled with a plurality of phase shifter circuits, with a phase shifter circuit of the plurality of phase shifter circuits controlling a phase shift amount of a signal input from a directional antenna of the plurality of directional antennas and delaying a phase of the signal according to a bias voltage output from the television tuner to control the directivity of the directional antenna for any direction, including an axial direction of the directional antenna and for generating a directivity value;
a tuner section that receives television broadcast signals in a predetermined band from the antenna and outputs an intermediate frequency (I/F) signal;
a signal condition detector section that detects a signal condition of the I/F signal, with the signal condition based on a channel number of a channel and directivity value;
if a frequency signal of the I/F signal is a digital frequency signal, the signal condition is determined by detecting a bit error rate; if the frequency signal of the I/F signal is an analog signal, the signal condition is determined by detecting an AGC voltage output;
a channel storing section that stores the channel number of the channel and the directivity value of the directional antenna as a channel select data if the signal condition of the I/F signal is commensurate with a predetermined signal condition;
if it is determined that the channel select data is stored, a video signal control processing is executed to display an image, after which, it is determined if an auto-scan start command has been input;
if it is determined that the channel select data is not stored, it is determined if the auto-scan start command is input;
if it is determined that the auto-scan start command is input, the auto scan processing is executed;
the auto-scan processing includes:
the tuner section receiving data that corresponds with a first channel number for setting the channel to the first channel number;
the directivity value of the antenna is set to a first directivity value using phase shifter circuits;
the signal condition detector section detecting the signal condition of the I/F signal output form the television tuner based on the set channel number and the directivity value;
determining if the detected signal condition is commensurate with the predetermined signal condition;
if the detected signal condition is commensurate with the predetermined signal condition, the channel storing section storing the set channel number and the set directivity value as the channel select data, after which, it is determined if one of the directivity value and the channel number, respectively, exceeds one of a predetermined directivity value and a predetermined channel number.

2. The television tuner for control of directivity of an antenna as set forth in claim 1, wherein:
the auto-scan processing further includes:
determining if the set directivity value is less than the predetermined directivity value; if it is determined that the set directivity value is less than the predetermined directivity value, incrementing the directivity value and detecting the signal condition based on the incremented directivity value and the set channel number; otherwise, if it is determined that the set directivity value is not less than the predetermined directivity value, then determining if the set channel number is less than the predetermined channel number; if so, incrementing the set channel to a higher channel number, resetting the directivity value, and detecting the signal condition based on a newly set channel number and the reset directivity value.

3. The television tuner for control of directivity of an antenna as set forth in claim 1, wherein:
the auto-scan processing further includes:
determining if the set channel number is less than the predetermined channel number; if so, incrementing the set channel to a higher channel number, resetting the directivity value, and detecting the signal condition based on a newly set channel number and the reset directivity value;
if the detected signal condition is not commensurate with the predetermined signal condition, determining if the set directivity value is less than the predetermined directivity value; if it is determined that the set directivity value is less than the predetermined directivity value, incrementing the directivity value and detecting the signal condition based on the incremented directivity value and the set channel number; otherwise, if it is determined that the set directivity value is not less than the predetermined directivity value, then determining if the set channel number is less than the predetermined channel number; if so, incrementing the set channel to a higher channel number, resetting the directivity value, and detecting the signal condition based on a newly set channel number and the reset directivity value.