U.S. patent application number 11/142653 was filed with the patent office on 2006-09-21 for television tuner.
This patent application is currently assigned to Funai Electric Co., Ltd.. Invention is credited to Takehiro Onomatsu, Kazuhiko Yamamoto.
Application Number | 20060209217 11/142653 |
Document ID | / |
Family ID | 35500025 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060209217 |
Kind Code |
A1 |
Onomatsu; Takehiro ; et
al. |
September 21, 2006 |
Television tuner
Abstract
Disclosed is a television tuner for receiving television
broadcast signals with an antenna, which is equipped with an
auto-scan unit that causes a channel storing section, which stores
a receiving channel at the time when the signal condition from a
tuner section matches the predetermined signal condition, to
automatically store the receiving channel, wherein the auto scan
unit detects switches among the receiving channel sequentially in
the tuner section to detect the signal condition, and, after signal
condition is detected for every channel, performs a variable
directivity control for the antenna, resulting in an increased
auto-scan execution speed.
Inventors: |
Onomatsu; Takehiro; (Osaka,
JP) ; Yamamoto; Kazuhiko; (Osaka, JP) |
Correspondence
Address: |
YOKOI & CO. U.S.A., INC.
13700 MARINA POINTE DRIVE #723
MARINA DEL RAY
CA
90292
US
|
Assignee: |
Funai Electric Co., Ltd.
Osaka
JP
|
Family ID: |
35500025 |
Appl. No.: |
11/142653 |
Filed: |
June 1, 2005 |
Current U.S.
Class: |
348/732 ;
348/570; 348/E5.097 |
Current CPC
Class: |
H04N 5/50 20130101; H01Q
21/205 20130101; H04N 21/4345 20130101; H04N 21/4384 20130101; H01Q
3/30 20130101; H04N 21/44209 20130101 |
Class at
Publication: |
348/732 ;
348/570 |
International
Class: |
H04N 5/50 20060101
H04N005/50 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2004 |
JP |
JP2004-164837 |
Claims
1. A television tuner that receives television broadcast signals
with a smart antenna capable of statically selecting a directivity
by means of an electric signal, comprising: 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 at the time 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 an
auto-scan unit switches the receiving channels at the tuner section
sequentially for the receiving channels except for the receiving
channels stored in the channel storing section, causes the signal
condition detector section to detect the signal condition for each
receiving channel, and, after signal condition is detected for
every receiving channel by the signal condition detector section,
causes a directivity control section to perform a variable
directivity control for the antenna.
2. A television tuner that receives television broadcast signals
with an antenna capable of selecting the directivity, comprising: a
directivity control section that outputs an electric signal to
select the directivity of the antenna; a tuner section that
receives television broadcast signals in the predetermined band
with the 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 when
the signal condition of a signal detected by the condition 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 switches among the
receiving channels sequentially for the plurality of receiving
channels, causes the signal condition detector section to detect
the signal condition for each receiving channel, and, after signal
condition is detected for every receiving channel by the signal
condition detector section, causes the directivity control section
to perform a variable directivity control for the antenna.
3. The television tuner according to claim 2, wherein the auto-scan
unit, after a receiving channel is stored in the channel storing
section, will not make a switch to the receiving channel
thereafter.
4. The television tuner according to claim 2, wherein the channel
storing section stores the receiving channel and the receiving
direction of the antenna at the time when the signal condition of a
signal detected by the signal condition detector section matches
the predetermined signal condition.
5. The television tuner according to claim 2, wherein: the antenna
is a smart antenna capable of statically selecting the directivity
by means of an electric signal; and the antenna control section
outputs an electric signal to statically select the directivity of
the smart antenna.
6. The television tuner according to claim 2, wherein the signal
condition detector section is an AGC circuit that detects the AGC
voltage specifying the gain of a signal from the tuner section.
7. The television tuner according to claim 2, wherein the signal
condition detector section is a demodulator circuit that detects
the bit error rate of a digital signal from the tuner.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a television tuner that
receives television broadcast signals with an antenna capable of
selecting directivity.
[0003] 2. Description of the Prior Art
[0004] 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.
[0005] Conventionally, there is known a television tuner that is
equipped with a smart antenna capable of statically changing the
directivity by means of an electrical signal, and that allows
finding a direction in which the desired channel can be best
received by automatically and omnidirectionaly changing the
directivity of the smart antenna (refer to Japanese Patent
Laid-Open No. 11-298226, for example).
[0006] Also, the above inventor proposes a television tuner that
receives television broadcast signals with the above-mentioned
smart antenna, wherein the smart antenna is controlled to change
the directivity of the smart antenna omnidirectionaly so as to find
a direction in which the desired radio wave is best received, and
also to switch receiving channels as appropriate and store
receiving channels sequentially which give optimum receiving
condition. This television tuner allows automatic storing of
receiving channels for all the receiving channels when performing
an auto-scan to set receivable television channels, and therefore
is very convenient.
[0007] However, this television tuner is designed to find the
optimum receiving condition by changing the directivity of the
smart antenna omnidirectionaly for all the receiving channels, as
described above. That is, it is necessary to perform the
omnidirectional directivity control of the smart antenna as many
times as the number of receiving channels repeatedly. Therefore, it
will take too much time if all the channels are scanned. In
particular, if the number of receivable channels is large this
problem is serious, making the user irritated or uncomfortable.
SUMMARY OF THE INVENTION
[0008] In view of the above problem, the present invention provides
a television tuner that allows a faster auto-scan.
[0009] 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;
[0010] 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
[0011] the auto-scan unit switches the receiving channels at the
tuner section sequentially for the receiving channels except for
the receiving channels stored in the channel storing section,
causes the signal condition detector section to detect signal
condition for each receiving channel, and, after signal condition
is detected for every receiving channel by the signal condition
detector section, causes the directivity control section to perform
a variable directivity control for the antenna.
[0012] In the aspect of the invention 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.
[0013] Furthermore, the auto-scan unit the auto-scan unit switches
the receiving channels at the tuner section sequentially, and,
after signal condition is detected for every receiving channel by
the signal condition detector section, causes the directivity
control section to perform a variable directivity control for the
antenna. This makes it possible to perform the variable directivity
control for the smart antenna with a one-time for every direction,
and thereby to increase the execution speed of the auto-scan.
[0014] Also, the auto-scan detects signal condition by switching
among the plurality of receiving channels except for the receiving
channels stored in the channel storing section. That is, if a
receiving channel is stored in the channel storing section, the
receiving channel at the tuner section is not switched to that
receiving channel nor the signal condition is detected. As a
result, the execution speed of the auto-scan can be further
increased.
[0015] Another aspect of the present invention is directed to a
television tuner that receives television broadcast signals with an
antenna capable of selecting the directivity, including:
a directivity control section that outputs an electric signal to
select the directivity of the antenna;
a tuner section that receives television broadcast signals in the
predetermined band with the 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 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
[0016] the auto-scan unit switches among the receiving channels
sequentially for the plurality of receiving channels, causes the
signal condition detector section to detect signal condition for
each receiving channel, and, after signal condition is detected for
every receiving channel by the signal condition detector section,
causes the directivity control section to perform a variable
directivity control for the antenna.
[0017] In the aspect of the invention 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 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.
[0018] Furthermore, the auto-scan unit switches the receiving
channels at the tuner section sequentially, and, after signal
condition is detected for every receiving channel by the signal
condition detector section, causes the directivity control section
to perform a variable directivity control for the antenna. This
makes it possible to perform the variable directivity control for
the smart antenna with a one-time for every direction, and thereby
to increase the execution speed of the auto-scan.
[0019] In the aspect of the present invention, the auto-scan unit,
after a receiving channel is stored by the channel storing section,
will not switch to that receiving channel thereafter. In this
configuration, if a receiving channel is stored in the channel
storing section, switching to that receiving channel will not be
made nor the detection of signal condition will be performed
thereafter, thus further increasing the execution speed of the
auto-scan.
[0020] In the aspect of the present invention, the channel storing
section may be so designed as to store the receiving channel and
the receiving direction of the antenna at the time 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.
[0021] In this configuration, since the receiving direction of the
antenna as well as the receiving channel at the time when the
signal condition of a signal detected by the signal condition
detector section matches the predetermined signal condition are
stored, it is possible to make the adjustment of the antenna
directivity quickly when a channel change command is input from the
remote control or the like.
[0022] In the aspect of the present invention, the antenna may be
designed such that it is a smart antenna capable of statically
selecting the directivity with an electric signal, and that the
antenna control section outputs an electric signal to statically
select the directivity of the smart antenna.
[0023] In this configuration, since it is possible to statically
select the directivity of the smart antenna with an electric signal
from the antenna control section, thus shortening the time needed
for variable directivity control for the smart antenna for every
direction.
[0024] In the aspect of the present invention, the signal condition
detector section is designed to be an AGC circuit that detects the
AGC voltage specifying the gain of a signal from the tuner
section.
[0025] In this configuration, it is possible to store the receiving
direction in which the signal condition of an intermediate
frequency from the tuner section is good.
[0026] In the aspect of the present invention, the signal condition
detector section may be designed to be a demodulator circuit that
detects the bit error rate of a digital signal from the tuner
section.
[0027] In this configuration, it is possible to store the receiving
direction in which the bit error rate of a signal from the tuner is
lower.
[0028] Note that each section and each unit of the television tuner
of the present invention may be contained in a television. That is,
the present invention can be applied to a television having a tuner
function.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a block diagram showing the configuration of a
television receiving system;
[0030] FIG. 2 is a block diagram showing the internal configuration
of a smart antenna unit;
[0031] FIG. 3 is a block diagram showing the internal configuration
of a television tuner;
[0032] FIG. 4 is conceptual diagram illustrating the smart antenna
unit;
[0033] FIG. 5 is shows an example of channel selection data;
[0034] FIG. 6 is a flowchart showing a main processing;
[0035] 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
[0036] FIG. 8 is a flowchart showing another example of the
auto-scan processing.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0037] 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.
[0038] 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.
[0039] FIG. 2 shows the internal configuration of the smart antenna
unit 10 schematically. 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.
[0040] 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 12 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.
[0041] FIG. 3 shows the internal configuration of the television
tuner 20 schematically. In the figure, the television tuner 20
comprises 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. 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.
[0042] 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.
[0043] 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.
[0044] 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 invention allows reproduction of both digital broadcast
signal and analog broadcast signal. The digital reproduction
section 23 comprises 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.
[0045] 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.
[0046] 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.
[0047] 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.
[0048] The MPEG decoder 23g is equipped with an OSD processing
section 23 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.
[0049] 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.
[0050] 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.
[0051] The analog reproduction section 24 comprises an analog I/F
24a, the demodulator circuit 24b, an NTSC decoder 24d, and an audio
decoder 24. 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.
[0052] Specifically, when the amplified 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.
[0053] 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.
[0054] 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.
[0055] 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, from which 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.
[0056] In the EEPROM 28d, for one example to be stored therein,
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,
and 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.
[0057] 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.
[0058] 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 40 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 if the
channel selection data 28d1 is not stored. Even when the channel
selection data 28d1 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.
[0059] 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.
[0060] 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.
[0061] 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 S101. In this processing,
processing for initialization, such as 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.
[0062] 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
current channel number stored in the EEPROM 28d. 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.
[0063] The processing of step S120 is performed, or 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.
[0064] The processing of step S140 is performed, or if it is
determined that the auto-scan start command is not input, 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.
[0065] Now, with reference to FIG. 7, the flow of auto-scan
processing is described that is invoked and executed at step S140.
First, the receiving direction pattern "D" is set to D=0 at step
S200. Also, a bias voltage corresponding to the set receiving
direction pattern (D=0) is supplied to each of the four phase
shifters 14 at step S210. This sets the directivity of the smart
antenna 10.
[0066] Next, the channel number ".alpha." is set to .alpha.=2 at
step S210. In addition, the processing for providing PLL data
corresponding to the set channel number to the tuner section 22 is
performed at step S200.
[0067] 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 29a.
[0068] 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.
[0069] 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 at step S240.
In this processing, the channel number set in the processing at
step S200 or at step S280 described below, and the receiving
direction pattern "D" that is identified as the predetermined
signal condition at step S230 are stored in the EEPROM 28d with
them corresponding to each other.
[0070] The processing of step S240 is performed, or if the detected
signal condition is not the predetermined signal condition at step
S230, it is checked if the channel number ".alpha." is
.alpha.<69. If .alpha.<69, the channel number is updated to
.alpha.=.alpha.+1 at step S260 and then control is returned to step
S220.
[0071] If .alpha.=69 (not .alpha.<69) at step S250, it is
checked if the receiving direction pattern "D" is D<15 at step
S270. If D<15, the receiving direction pattern is updated to
D=D+1 at step S280 and control is returned to step S210. If D=15
(not D<15), the auto-scan processing is finished.
[0072] Now, a specific example of the auto-scan processing shown in
FIG. 7 is described with reference to FIG. 5. First, the receiving
direction pattern is set to D=0 (step S200), and then the channel
number is set to .alpha.=2 (step S210). Then, the signal condition
at this channel number is detected (step S220) and the detected
signal condition is identified (step S230). As shown in FIG. 5,
when the receiving direction pattern is D=0 the signal condition is
good when the channel number is .alpha.=14. 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.
[0073] The signal condition when the receiving pattern is D=0 is
detected and identified, and then the channel number is set to
.alpha.=3 (step S260), the detection and identification of the
signal condition is performed for this channel number (steps S220
and S230). According to this procedure, the channel number is
incremented by one with the receiving direction pattern is fixed at
D=0, and the detection and identification of the signal condition
is performed for each channel number. When the channel number is
.alpha.=14, the signal condition is good, and thus the channel
number (.alpha.=14) and receiving direction pattern (D=0) for this
channel is stored in the EEPROM 28d (step S240). After they are
stored, while the channel number is incremented by one, the
detection and identification of the signal condition is performed
for each channel number, as in the above. When the detection and
identification of the signal condition is performed for the channel
number .alpha.=69, the receiving direction pattern is incremented
by one and set to D=1 (step S280) and the channel number is
switched within the range of .alpha.=2 to 69, and also the
detection and identification of the signal condition is performed
for each channel number.
[0074] Thus, the television tuner 20 detects the signal condition
of the frequency signal from the tuner section 22 while switching
the channel number within the range .alpha.=2 to 69 with the
receiving direction pattern fixed, and when .alpha.=69 and the
detection for all the channels is completed, the receiving
direction pattern is switched. Then, when the signal condition
becomes the predetermined signal condition for a channel number,
the channel number and receiving direction pattern for that channel
number are sequentially stored in the EEPROM 28d with them
corresponding to each other, in order to produce the channel
selection data 28d1.
[0075] In FIG. 7, the channel number and receiving direction
pattern are stored in the EEPROM 28d at step S240, but the
television tuner 20 may be implemented such that only the channel
number is stored in the EEPROM 28d. By implementing like this, it
is possible to increase the speed of the auto-scan processing since
the time for storing the receiving direction pattern will not be
needed. Also, since the receiving direction pattern is searched
each time a channel number change command is input from the remote
control 40 or the like, it is possible to receive television
broadcast signals giving stable images continuously.
[0076] Described with reference to FIG. 7 is the case where,
regardless of whether the channel number is stored in the EEPROM
28d when the detected signal condition matches the predetermined
signal condition, all the channel numbers are switched for each
receiving direction pattern, and signal condition is detected for
every channel number. However, if it is determined that the signal
condition for a channel number is the predetermined signal
condition, and that channel number is stored in the EEPROM 28d, the
television tuner 20 may be implemented such that switching to that
channel number will not be made thereafter.
[0077] Now, another example of the main processing to be executed
in the television tuner 20 is described. In FIG. 8, after the
processing of step S260 is performed, it is checked if the channel
number is stored at step S400. This processing checks if the
channel number that has been updated at step S260 is already stored
in the EEPROM 28d. If the channel number is stored, the value of
the channel number is updated to .alpha.=.alpha.+1. Then, the
processing of step S410 is performed, or if it is determined that
the channel number is not stored at step S400, control is returned
to step S220.
[0078] Now, a specific example of the auto-scan processing shown in
FIG. 8 is described with reference to FIG. 5. First, the receiving
direction pattern is set to D=0 (step S200), and then the channel
number is set to .alpha.=2 (step S210). Then, the signal condition
at this channel number is detected (step S220) and the detected
signal condition is identified (step S230). As shown in FIG. 5,
when the receiving direction pattern is D=0, the signal condition
is good when the channel number is .alpha.=14. 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.
[0079] The signal condition, when the receiving pattern is D=0, is
detected and identified, and then the channel number is set to
.alpha.=3 (step S260), the detection and identification of the
signal condition is performed for this channel number. According to
this procedure, the channel number is incremented by one with the
receiving direction pattern fixed at D=0, and the detection and
identification of the signal condition is performed for each
channel number. When the channel number is .alpha.=14, the signal
condition is good, and thus the channel number (.alpha.=14) and
receiving direction pattern (D=0) for this channel is stored in the
EEPROM 28d (step S240). After they are stored, while the channel
number is incremented by one, the detection and identification of
the signal condition is performed for each channel number, as in
the above. When the detection and identification of the signal
condition is performed for the channel number .alpha.=69, the
receiving direction pattern is incremented by one and set to D=1
(step S280), and the channel number is switched within the range of
.alpha.=2 to 69. However, since the channel number ".alpha.=14" is
already stored in the EEPROM 28d, the processing of step S410 is
performed to further increment the channel number a by one, making
it impossible to switch to channel number .alpha.=14. That is, the
channel number switching for the receiving direction pattern D=1 is
made within the range of .alpha.=2 to 13 and 15 to 69. By doing
this, switching to a channel number already stored in the EEPROM
28d will not be made nor the detection and identification of the
signal condition will be performed, thus making it possible to
further increase the execution speed of the auto-scan.
[0080] In the above embodiments, the television tuner that receives
television broadcast signals with the smart antenna capable of
statically selecting the directivity with an electric signal was
described. However, the present invention is not limited to the
television tuner using the smart antenna, it is possible to
implement a television tuner that receives television broadcast
signals with an antenna capable of dynamically selecting the
directivity. Specifically, for example, a television tuner with a
directional antenna that has the directivity in certain direction
and that can be rotated on a horizontal surface by means of a drive
unit such as a motor may be implemented according to the present
invention.
[0081] As described above, according to the present invention, the
variable directivity control for the antenna can be made by a
one-time operation for each direction and thus the execution speed
of the auto-scan can be increased.
[0082] The foregoing invention has been described in terms of
preferred embodiments. However, those skilled, in the art will
recognize that many variations of such embodiments exist. Such
variations are intended to be within the scope of the present
invention and the appended claims.
* * * * *