JPH0983400A - Channel selection device and receiver using the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the channel selection of both of television/radio broadcasting by sharing a local oscillation circuit. SOLUTION: A receiver 10 receives television broadcasting and FM radio broadcasting. When a mode is set to a television reception mode by the operation of a key operation part or a transmitter, a local oscillation signal STLO and a television channel signal STCH are mixed, a television intermediate frequency signal STIF is outputted. When the mode is set to an FM reception mode, the local oscillation signal STLO is frequency-divided into 1/2 by a frequency divider 32, the resultant signal is mixed with an FM signal SFCH and the FM intermediate frequency signal SFIF of a frequency 4.5Mhz is outputted. Therefore, the channel selection of the television broadcasting and the FM radio broadcasting can be performed by sharing a local oscillation circuit 12 for television broadcasting, and further, a voice intermediate frequency filter circuit 61 and an FM detection circuit 62, etc., can be shared. Therefore, cost merit and space merit can sufficiently be realized as compared with the case where a television receiver and a radio receiver are individually provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel selection device and a receiver using the channel selection device. Specifically, by sharing the local oscillation circuit for obtaining the local oscillation signal to be supplied to the mixing circuit that outputs the television intermediate frequency signal and the mixing circuit that outputs the radio intermediate frequency signal, sufficient cost and space advantages can be obtained. The present invention relates to a channel selection device that can be enjoyed and a receiver that uses the channel selection device.

[0002]

2. Description of the Related Art Conventionally, a receiver capable of receiving both television broadcasting and radio broadcasting such as FM radio broadcasting is known. This receiver is very convenient because the user can enjoy both television broadcasting and radio broadcasting.

[0003]

By the way, in the receiver capable of receiving both the television broadcast and the radio broadcast described above, a local oscillation circuit for outputting a local oscillation signal in a frequency band suitable for the channel of each broadcast to be selected is provided. is necessary.

For example, frequency allocation for television broadcasting is VHF.
Bands 1 to 3 channels (VHF low channel) are 90 MHz to 108 MHz, VHF band 4 channels to 1
170M for 2 channels (VHF high channel)
Hz to 222MHz, UHF band (13 to 62 channels)
Is 470 MHz to 770 MHz (occupied bandwidth per channel is 6 MHz). The local oscillation frequency of each channel required for channel selection is set to be higher than the video carrier frequency of that channel by 58.75 MHz, and the local oscillation circuit for TV broadcast channel selection is 150 MHz to 162 MHz.
MHz, 230 MHz to 276 MHz and 530 MHz
It is necessary to output a local oscillation signal having a frequency of ˜824 MHz.

The frequency allocation of FM radio broadcasting is 7
6.1 MHz to 89.9 MHz (total of 139 channels, occupied bandwidth per channel is 100 kHz =
0.1 MHz). The local oscillation frequency of each channel required for tuning is 10.7 MHz from the carrier frequency of that channel.
However, the local oscillation circuit for FM broadcast channel selection needs to output a local oscillation signal having a frequency of 65.4 MHz to 79.2 MHz.

However, there is currently no general-purpose local oscillation circuit capable of independently outputting a local oscillation signal in the frequency band necessary for selecting both (all or part of) FM radio broadcasting and television broadcasting. Therefore, in order to select both FM radio broadcasting and TV broadcasting without using a special local oscillation circuit, a local oscillation circuit for TV broadcast tuning and a local oscillation signal of 65.4 MHz to 79.2 MHz are used. It is necessary to have a local oscillating circuit dedicated to FM broadcasting tuning capable of oscillating. Also, the high-frequency amplifier circuit and the mixing circuit must have the ones for each broadcasting as well as the local oscillation circuit.

Further, the frequency of the audio second intermediate frequency signal of the television broadcast is 4.5 MHz, but the frequency of the audio intermediate frequency signal of the FM radio broadcast is 10.7 MHz. Therefore, in the receiver, the audio intermediate frequency signal is Each component that is used according to the frequency of the audio intermediate frequency signal of each broadcast to be supplied, such as a bandpass filter or a detection filter of the audio processing unit that processes the .

As described above, in the conventional receiver capable of receiving both the television broadcast and the radio broadcast, each circuit such as the local oscillation circuit of the channel selection section must be separately provided for the television broadcast and the radio broadcast. . In addition, some components of the audio processing unit for television broadcasting and radio broadcasting must be separately provided. Therefore, the cost merit and space merit due to the integration of the television receiver and the radio receiver cannot be enjoyed so much.

Therefore, the present invention provides a channel selection device and a receiver using the channel selection device, which can fully enjoy the cost merit and space merit by integrating a television receiver and a radio receiver.

[0010]

A tuning device according to the present invention mixes a local oscillation circuit for outputting a local oscillation signal with a television broadcast signal and a first frequency signal to output a television intermediate frequency signal. A first mixing circuit and a second mixing circuit for mixing the radio broadcast signal and the second frequency signal to output a radio intermediate frequency signal are provided, and the first and second frequency signals are output from the local oscillation circuit. It is obtained from the output local oscillation signal.

Further, in the tuning apparatus according to the present invention, the first frequency signal is the local oscillation signal output from the local oscillation circuit, and the second frequency signal is the local oscillation signal through the frequency divider. I will get it.

Alternatively, in the channel selection device according to the present invention, the second frequency signal is the local oscillation signal output from the local oscillation circuit, and the first frequency signal is obtained through the multiplier of the local oscillation signal. It is a thing.

Further, in addition to the above-mentioned configuration, the tuning apparatus according to the present invention is such that the frequency of the radio intermediate frequency signal is equal to the difference frequency between the video intermediate frequency signal and the audio intermediate frequency signal included in the television intermediate frequency signal. It should be equal.

Further, the receiver according to the present invention comprises a first mixing circuit for mixing a television broadcast signal and a first frequency signal obtained from the first local oscillation circuit to output a television intermediate frequency signal, A second mixing circuit that mixes a radio broadcast signal and a second frequency signal obtained from a second local oscillation circuit to output a radio intermediate frequency signal, and a video intermediate frequency signal and audio included in the television intermediate frequency signal An intermediate frequency filter circuit for extracting a second audio intermediate frequency signal from the intermediate frequency signal, and either an audio second intermediate frequency signal extracted by the intermediate frequency filter circuit or a radio intermediate frequency signal output by the second mixing circuit. And a voice processing unit that processes an output signal of the switch circuit and outputs a voice signal.

Further, in the receiver according to the present invention, the first and second local oscillation circuits are one oscillation circuit.

The first frequency signal and the second frequency signal are obtained from the local oscillation signal output from the local oscillation circuit, and the first mixing circuit mixes the television broadcast signal and the first frequency signal to produce a television intermediate signal. A frequency signal is output. The second mixing circuit mixes the radio broadcast signal and the second frequency signal and outputs a radio intermediate frequency signal.

The first frequency signal is the local oscillation signal itself output from the local oscillation circuit, and the second frequency signal is obtained from the local oscillation signal via the frequency divider.

Alternatively, the second frequency signal is the local oscillation signal itself output from the local oscillation circuit, and the first frequency signal is obtained via the multiplier of the local oscillation signal.

Further, the frequency of the radio intermediate frequency signal is made equal to the frequency of the difference between the video intermediate frequency signal and the audio intermediate frequency signal included in the television intermediate frequency signal.

In the receiver, either the audio second intermediate frequency signal or the radio intermediate frequency signal is selectively output by the switch circuit, processed by the audio processing unit and output as an audio signal.

[0021]

DETAILED DESCRIPTION OF THE INVENTION A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a receiver as an embodiment. The receiver 10 can receive both television broadcasting and FM radio broadcasting.

The receiver 10 shown in FIG. 1 comprises a television broadcast channel selection unit 1, a video processing unit 2, an FM broadcast channel selection unit 3, a changeover switch 4 constituting a switch circuit, and a microcomputer constituting a system controller (hereinafter referred to as "microcomputer"). 5) and a voice processing unit 6.

The television broadcasting channel selection unit 1 is provided with a high frequency amplifier circuit 1.
1 and a local oscillation circuit 12 that constitutes a frequency conversion circuit and a television broadcast mixing circuit 13 as a first mixing circuit.

The high frequency amplifier circuit 11 is supplied with the high frequency television broadcast signal S _TVB captured by the television broadcast receiving antenna AT _TV . In the high frequency amplifier circuit 11, only the signal in the band corresponding to the desired channel is selected by tuning from the television broadcast signal S _TVB supplied from the antenna AT _TV . The selected signal (hereinafter, referred to as “television channel signal”) S _TCH is amplified to a level required for the processing of the next stage and supplied to the mixing circuit 13. The tuning frequency is controlled by the microcomputer 5.

Further, from the local oscillator circuit 12, in the television receiving mode, the frequency of the video carrier frequency of the television channel signal S _TCH selected by the high frequency amplifier circuit 11 is 58.
The local oscillation signal S _TLO as the first frequency signal having a frequency higher by 75 MHz is output. For example, when the desired channel is one channel, the frequency f _TLO of the local oscillation signal output by the local oscillation circuit 12 is 150.0 MHz. The oscillation frequency is controlled by the microcomputer 5.

The mixing circuit 13 is supplied with the television channel signal S _TCH from the high frequency amplifier circuit 11 and the local oscillation signal S _TLO (frequency f _TLO ) from the local oscillation circuit 12 to mix both signals. Then, from the mixing circuit 13, only the signal of the frequency of the difference between the two signals is taken out by the resonance circuit arranged at the output part thereof, and this is supplied to the video processing part 2 as the television intermediate frequency signal S _TIF .

The image processing section 2 includes an intermediate frequency filter circuit 2
1 and a video detection circuit 22.

The intermediate frequency filter circuit 21 is supplied with the television intermediate frequency signal S _TIF (58.75 MHz video intermediate frequency signal and 54.25 MHz audio first intermediate frequency signal) from the mixing circuit 13 and is amplified. Filter circuit 21
The amplified video intermediate frequency signal S _VIF is _supplied to the video detection circuit 22.
And is subjected to AM detection processing, and the video signal SV extracted by this AM detection processing is supplied to a video reproduction system (not shown).

Further, in the intermediate frequency filter circuit 21, the above-mentioned intermediate frequency signal S _TIF is amplitude-detected, and the audio second intermediate frequency signal S _2IF (video intermediate frequency signal and audio first frequency signal whose audio carrier frequency is 4.5 MHz) is detected. The difference signal of the intermediate frequency signal) is taken out. The extracted second audio intermediate frequency signal S _2IF is supplied to the fixed terminal on the side a of the changeover switch 4.

The FM broadcasting channel selection section 3 includes a high frequency amplifier circuit 31.
, A frequency divider 32, and an FM broadcast mixing circuit 33 as a second mixing circuit.

The high frequency amplifier circuit 31 is supplied with the high frequency FM radio broadcast signal S _FMB captured by the FM broadcast receiving antenna AT _FM . In the high frequency amplifier circuit 31, the FM radio broadcast signal S _FMB supplied from the antenna AT _FM
From among the above, only the signal in the band corresponding to the desired channel is selected by tuning. Selected signal (hereinafter "F
The S _{FCH (referred to as} “M channel signal”) is amplified to a level required for the processing of the next stage and supplied to the mixing circuit 33. The tuning frequency is controlled by the microcomputer 5.

The frequency divider 32 is a station of the TV broadcasting channel selection unit 1.
Local oscillation signal S from local oscillation circuit 12 _TLO(Frequency f_TLO)
Is supplied and the frequency is divided in half. This second frequency
The divided signal S as a signal_DEM(Frequency f_TLO/
2) is supplied to the mixing circuit 33. In this case,
The frequency of the local oscillation signal output from the oscillation circuit 12 is F
In the M reception mode, the divided signal S_DEMFrequency is F
M channel signal S_FCHIt is 4.5MHz from the carrier frequency of
It is controlled by the microcomputer 5 so that it becomes lower or higher.
Is controlled. For example, the desired FM channel signal S_FCHof
If the carrier frequency is 82.5 MHz, the divided signal
S_DEMFrequency is 78.0MHz or 87.0MHz
Frequency 156MHz or 174MHz
The local oscillation signal is output from the local oscillation circuit 12.

The mixing circuit 33 is supplied with the FM channel signal S _FCH from the high frequency amplifying circuit 31 and also receives the frequency divider 3
The frequency- _divided signal S _DEM as the second frequency signal is supplied from 2 to mix both signals. Then, from the mixing circuit 33, only the signal of the frequency of the difference between the two signals is taken out by the resonance circuit arranged at the output part thereof, and this is output to the fixed terminal on the b side of the changeover switch 4 as the FM intermediate frequency signal S _FIF. Supplied.

In this way, the audio second intermediate frequency signal S output from the intermediate frequency filter circuit 21 of the video processing unit 2
_2IF is supplied to the fixed terminal on the a side of the changeover switch 4, and the FM intermediate frequency signal S _FIF output from the mixing circuit 33 is supplied to the fixed terminal on the b side of the changeover switch 4.

The changeover operation of the changeover switch 4 is controlled by the control signal SC _SW . When the television reception mode is set, the changeover switch 4 is connected to the a side,
When the FM reception mode is set, the changeover switch 4 is connected to the b side.

The above-mentioned reception mode setting is determined by the user operating the key operation unit 9 connected to the microcomputer 5. A broadcast channel selection button is provided on the key operation unit 9, and a user presses each button to set a channel for television broadcasting and FM radio broadcasting.

The audio processing unit 6 has an audio intermediate frequency filter circuit 61 and an FM detection circuit 62.

The audio intermediate frequency filter circuit 61 is 4.5M.
It has a band pass filter of Hz. The audio intermediate frequency filter circuit 61 is supplied with the audio second intermediate frequency signal S _2IF or the FM intermediate frequency signal S _FIF from the movable terminal c of the changeover switch 4, and is subjected to band limiting processing and amplification processing to extract the intermediate frequency signal SIF. Be done.

The intermediate frequency signal SIF extracted by the audio intermediate frequency filter circuit 61 is supplied to the FM detection circuit 62 to perform FM detection processing. The audio signal SA extracted by this FM detection processing is supplied to an audio reproduction system (not shown).

2A to 2D show the relationship between the reception frequency of the receiver 10 of this embodiment and the local oscillation frequency. The case where the frequency-divided signal in the FM broadcast reception mode is lowered by 4.5 MHz from the FM channel signal is shown, and only the portion of channels 1 to 3 is shown for television broadcasting.

As shown in FIG. 2A, the VHF band 1 to
Three-channel TV broadcast signal S _TVB (frequency f _TVB : 90
MHz to 108 MHz), the minimum required frequency of the local oscillation signal S _TLO , f _TLO , is 150 MHz.
z to 162 MHz. Therefore, the local oscillation circuit 12
The oscillator having a frequency of 140 MHz to 172 MHz as shown in FIG. 2B is used so as to cover the band of 150 MHz to 162 MHz.

On the other hand, the band of the frequency f _FMB of the FM broadcast signal S _FMB is 76.1 MHz to 8 as shown in FIG. 2 (d).
It is 9.9 MHz. The frequency f _DEM of the frequency- _divided signal S _DEM that is the minimum required to select this FM radio broadcast signal S _FMB.
The band of 71.6 MHz to, as shown in FIG.
It is 85.4 MHz.

Therefore, the minimum frequency band of the local oscillation signal S _{T LO} required to select the FM broadcast signal S _FMB is 143.2 MHz to 17 as shown in FIG. 2 (c).
It becomes 0.8 MHz, which is 1 to 1 of the local oscillation circuit 12 described above.
It is fully covered by a 3-channel oscillator.

In the above configuration, when the television reception mode is set, the local oscillation signal of the television channel selected by the key operation unit 9 is output from the local oscillation circuit 12 and the local oscillation signal is mixed. It is supplied to the circuit 13. The television intermediate frequency signal output from the mixing circuit 13 is supplied to the filter circuit 21 of the video processing unit 2. The audio second intermediate frequency signal output from the filter circuit 21 is supplied to the fixed terminal on the a side of the changeover switch 4. At this time,
The changeover switch 4 is connected to the fixed terminal on the a side, and the audio second intermediate frequency signal is supplied to the audio processing unit 6. As a result, the audio processing unit 6 outputs the audio signal SA relating to the selected television broadcast to the audio system. The video processing unit 2
From, the video signal SV related to the selected television broadcast is output to the video system. Further, when the FM reception mode is set, the local oscillation signal for the FM channel selected by the key operation unit 9 is output from the local oscillation circuit 12, divided by the frequency divider 32, and mixed by the mixing circuit 33. Is supplied to. The FM intermediate frequency signal output from the mixing circuit 33 is the changeover switch 4
Is supplied to the fixed terminal on the b side. At this time, the changeover switch 4 is connected to the fixed terminal on the b side, and the FM intermediate frequency signal is supplied to the audio processing unit 6. As a result, the audio processing unit 6 outputs the audio signal SA relating to the selected FM broadcast to the audio system.

As described above, according to this embodiment, when the television reception mode is set, the local oscillation signal S _TLO output from the local oscillation circuit 12 and the television channel output from the high frequency amplification circuit 11 are set. The signal S _TCH is mixed by the mixing circuit 13 and the television intermediate frequency signal S _TIF is output. On the other hand, when the FM reception mode is set, the local oscillation signal S _TLO is frequency- _divided by the frequency divider 32 into 1/2, and the 1/2 frequency- _divided signal S _DEM and the high frequency amplification circuit 31 are
F mixed with the FM channel signal S _FCH output from
The M intermediate frequency signal S _FIF is output. Therefore, it is possible to select the television broadcast and the FM radio broadcast by sharing the local oscillation circuit 12 for the television broadcast.

Further, F supplied from the mixing circuit 33 of the FM broadcast channel selection unit 3 to the audio processing unit 6 via the changeover switch 4.
The frequency f _FIF of the M intermediate frequency signal S _FIF is set to 4.5 MHz, and is similarly made equal to the frequency f _{2IF of the} audio second intermediate frequency signal S _2IF supplied to the audio processing unit 6 via the changeover switch 4. . Therefore, the audio intermediate frequency filter circuit 6
It is possible to share a circuit used according to the frequency of each of the audio intermediate frequency signals S _2IF and S _FIF supplied from the changeover switch 4, such as 1 and the FM detection circuit 62.

Therefore, it is possible to fully enjoy the cost merit and space merit as compared with the one in which the television receiver and the radio receiver are simply integrated.

Next, a receiver 30 as another embodiment of the present invention will be described with reference to FIG. In FIG. 3 showing the structure of the receiver 30, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted. Also in this embodiment, as in the example of FIG. 1, it is possible to receive both the television broadcast and the FM radio broadcast.

In the present embodiment, the TV broadcast channel selection unit 1 and the FM broadcast channel selection unit 3 in the example of FIG. 1 are replaced with the TV broadcast channel selection unit 7 and the FM broadcast channel selection unit 8, respectively.

The television broadcasting channel selection section 7 is a high frequency amplifier circuit 1.
Television broadcast mixing circuit 13 as first and first mixing circuit
And a multiplier 72 that replaces the local oscillator circuit 12 in the example of FIG. Further, the FM broadcast channel selection unit 8 has a high frequency amplifier circuit 31, an FM broadcast mixing circuit 33 as a second mixing circuit, and a local oscillation circuit 82 that replaces the frequency divider 32 in the example of FIG. Others are configured similarly to the example of FIG.

From the local oscillation circuit 82 of the FM broadcasting channel selection unit 8, in the FM reception mode, the first or second frequency lower or higher than the carrier frequency of the FM channel signal S _FCH selected by the high frequency amplifier circuit 31 by 4.5 MHz. The local oscillation signal S _FLO as the frequency signal of 2 is output. For example, if the carrier frequency of the desired channel is 82.5 MH
In the case of z, the frequency f _FLO of the local oscillation signal output by the local oscillation circuit 82 is 78.0 MHz or 87.0 MHz. The oscillation frequency is controlled by the microcomputer 5 as in the local oscillation circuit 12 in the example of FIG.

The mixing circuit 33 includes a high frequency amplifier circuit.
FM channel signal S from 31_FCHIs supplied with the station
Local oscillation signal S from local oscillation circuit 82_FLOSupplied by both
The signals are mixed. Then, from the mixing circuit 33,
The frequency of the difference between the two signals due to the resonant circuit placed at the output
Is taken out, and this is the FM intermediate frequency signal S
_FIFIs supplied to the fixed terminal on the b side of the changeover switch 4 as
You.

The multiplier 72 of the television broadcasting channel selection section 7 has an F
The local oscillation signal S is output from the local oscillation circuit 82 of the M broadcasting channel selection unit 8.
_FLO (frequency f _FLO ) is supplied and doubled. This doubled signal S as the first frequency signal
_{The MUL} (frequency 2f _FLO ) is supplied to the mixing circuit 13. In this case, the frequency of the local oscillation signal output from the local oscillation circuit 82 is the multiplied signal S in the television receiving mode.
_The microcomputer 5 controls the _MUL frequency to be higher than the video carrier frequency of the television channel signal S _TCH by 58.75 MHz. For example, the video carrier frequency of the desired TV channel signal S _TCH is 91.25 MHz
In the case of (1 channel), a local oscillation signal having a frequency of 75.0 MHz is output from the local oscillation circuit 82 so that the frequency of the multiplied signal S _{M UL} becomes 150.0 MHz.

Further, the mixing circuit 13 is supplied with the television channel signal S _TCH from the high-frequency amplifier circuit 11 and is multiplied by the multiplier 72 as the first frequency signal.
_MUL is supplied and both signals are mixed and both signals are mixed. Then, from the mixing circuit 13, only the signal of the frequency having the difference between the two signals is taken out by the resonance circuit arranged at the output part thereof, and this is taken as the intermediate frequency filter circuit 21 of the video processing part 2 as the television intermediate frequency signal S _TIF. Is supplied to.

As described above, the example of FIG. 3 is configured similarly to the example of FIG.

Each of FIGS. 4A to 4D shows the relationship between the reception frequency and the local oscillation frequency of the receiver 20 of this embodiment. In addition, the case where the local oscillation signal in the FM broadcast reception mode is lowered by 4.5 MHz from the FM channel signal is shown.
Only the part of 3 channels is shown.

As shown in FIG. 4D, the band of the frequency f _FLO of the local oscillation signal S _FLO which is the minimum necessary for selecting the FM radio broadcast (frequency f _FMB : 76.1 MHz to 89.9 MHz). Is the frequency f of the intermediate frequency signal S _{FIF to be} extracted.
_{If FIF} is 4.5MHz, 71.6MHz ~ 85.4M
Hz. Therefore, as the frequency of the local oscillator circuit 82, for example, 70 MHz as shown in FIG. 4C so as to cover the band of 71.6 MHz to 85.4 MHz.
Used in those with a frequency of ~ 86MHz.

On the other hand, the band of the frequency f _FMB of the television broadcast signal S _TVB of 1 to 3 channels in the VHF band is 90 MHz to 108 MHz as shown in FIG. 4 (a). The band of the frequency f _MUL of the multiplied signal S _MUL which is the minimum necessary for selecting the television radio broadcast signal S _TVB is 150.0 MHz to 162.0 MHz as shown in FIG.

Therefore, the minimum frequency band of the local oscillation signal S _FLO required for selecting the television broadcast signal S _TVB of 1 to 3 channels is 75.
The frequency becomes 0 MHz to 81.0 MHz, which is sufficiently covered by the oscillation frequency of the local oscillation circuit 82 described above.

In the above configuration, when the FM reception mode is set, the local oscillation signal of the FM channel selected by the key operation unit 9 is output from the local oscillation circuit 82, and this local oscillation signal is mixed. It is supplied to the circuit 33. The FM intermediate frequency signal output from the mixing circuit 33 is supplied to the fixed terminal on the a side of the changeover switch 4. At this time, the changeover switch 4 is connected to the fixed terminal on the b side, and the FM intermediate frequency signal is supplied to the audio processing unit 6. As a result, the audio processing unit 6 outputs the audio signal SA relating to the selected FM radio broadcast to the audio system. When the television reception mode is set, the local oscillation signal for the television channel selected by the key operation unit 9 is output from the local oscillation circuit 82, multiplied by the multiplier 72, and supplied to the mixing circuit 13. To be done. The television intermediate frequency signal output from the mixing circuit 13 is supplied to the filter circuit 21 of the video processing unit 2. The audio second intermediate frequency signal output from the filter circuit 21 is supplied to the fixed terminal on the a side of the changeover switch 4. At this time, the changeover switch 4 is connected to the fixed terminal on the a side, and the audio second intermediate frequency signal is supplied to the audio processing unit 6. As a result, the audio processing unit 6 outputs the audio signal SA relating to the selected television broadcast to the audio system. The video processing unit 2 outputs the video signal SV related to the selected television broadcast to the video system.

As described above, according to the second embodiment, when the FM reception mode is set, the local oscillation signal S _TLO output from the local oscillation circuit 82 and the high frequency amplification circuit 31 output. FM channel signal S _FCH
And are mixed by the mixing circuit 33, and the FM intermediate frequency signal S _FIF is mixed.
Is output. On the other hand, when the television reception mode is set, the local oscillation signal S _TLO is _doubled by the multiplier 72, and the doubled signal S _DEM and the television channel signal S _TCH output from the high frequency amplifier circuit 11 are generated. Mixing circuit 13
And the television intermediate frequency signal _STIF is output.
Therefore, it is possible to select the television broadcast and the FM radio broadcast by sharing the local oscillation circuit 82 for the FM radio broadcast.

According to the second embodiment, similarly to the first embodiment described above, the signal is supplied from the mixing circuit 33 of the FM broadcast channel selection unit 3 to the audio processing unit 6 via the changeover switch 4. that frequency f _FIF of the FM intermediate frequency signal S _FIF 4.5
In the same manner, the frequency is made equal to the frequency f _{2IF of the} audio second intermediate frequency signal S _2IF supplied to the audio processing unit 6 via the changeover switch 4. Therefore, the changeover switch 4 such as the audio intermediate frequency filter circuit 61 and the FM detection circuit 62.
The circuits used according to the frequencies of the respective audio intermediate frequency signals S _2IF and S _{F IF} supplied from

Therefore, as in the first embodiment described above, it is possible to fully enjoy the cost merit and space merit as compared with the one in which the television receiver and the radio receiver are simply integrated.

In the above first and second embodiments, the one applied to the receiver capable of receiving the television broadcast and the FM radio broadcast is shown.
It goes without saying that the present invention can also be applied to receivers that can receive radio broadcasting.

Further, in the above-described first and second embodiments, by setting the FM intermediate frequency to 4.5 MHz, the audio processing of the audio second intermediate frequency signal and the FM intermediate frequency signal of the television broadcast is common. However, the audio processing units for television broadcasting and FM radio broadcasting may be provided separately. For example, set the FM intermediate frequency to 1
If set to 0.7 MHz, the conventional audio processing unit can be used as the audio processing unit for the FM intermediate frequency signal.

[0066]

According to the present invention, the first frequency signal and the second frequency signal are obtained from the local oscillation signal output from one local oscillation circuit, and the television broadcast signal and the first frequency signal are obtained. A television intermediate frequency signal is mixed and outputted, and a radio broadcast signal and a second frequency signal are mixed and a radio intermediate frequency signal is outputted. Therefore, both television broadcasting and radio broadcasting can be selected by sharing one local oscillation circuit. Further, the frequency of the radio intermediate frequency signal is made equal to the frequency of the difference between the video intermediate frequency signal and the audio intermediate frequency signal included in the television intermediate frequency signal. Therefore, each circuit used according to the frequency of each audio intermediate frequency signal of a television broadcast signal and a radio broadcast signal can be shared. Therefore, it is possible to fully enjoy the cost merit and the space merit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a receiver as a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a reception frequency and a local oscillation frequency.

FIG. 3 is a block diagram showing a configuration of a receiver as a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a reception frequency and a local oscillation frequency in the second embodiment shown in FIG.

[Explanation of symbols]

1 TV broadcast channel selection section 2 Video processing section 3 FM broadcast channel selection section 4 Changeover switch 5 Microcomputer 6 Audio processing section 7 TV broadcast channel selection section 8 FM broadcast channel selection section 10 Receiver 11 High frequency amplification circuit 12 Local oscillation circuit 13 TV broadcast mixing circuit 20 Receiver 21 Intermediate Frequency Filter Circuit 22 Video Detection Circuit 31 High Frequency Amplifier Circuit 32 Frequency Divider 33 FM Broadcast Mixing Circuit 61 Audio Intermediate Frequency Filter Circuit 62 FM Detection Circuit 72 Multiplier 82 Local Oscillation Circuit AT _TV Television Broadcast Reception Antenna AT _{FM FM} radio broadcasting receiving antenna

Claims (10)

[Claims] 1. A local oscillation circuit that outputs a local oscillation signal, a first mixing circuit that mixes a television broadcast signal and a first frequency signal and outputs a television intermediate frequency signal, a radio broadcast signal and a second A second mixing circuit that mixes with the frequency signal of 1 to output a radio intermediate frequency signal, wherein the first and second frequency signals are obtained from a local oscillation signal output from the local oscillation circuit. And a tuning device. 2. The first frequency signal is a local oscillation signal output from the local oscillation circuit, and the second frequency signal is the local oscillation signal obtained via a frequency divider. The tuning device according to claim 1, characterized in that 3. The second frequency signal is a local oscillation signal output from the local oscillation circuit, and the first frequency signal is obtained by passing the local oscillation signal through a multiplier. The tuning device according to claim 1. 4. The frequency of the radio intermediate frequency signal is set to be equal to the frequency of the difference between the video intermediate frequency signal and the audio intermediate frequency signal included in the television intermediate frequency signal. Tuning device. 5. The channel selection device according to claim 1, wherein the radio broadcast signal is an FM radio broadcast signal. 6. The tuning apparatus according to claim 1, wherein the radio broadcast signal is an AM radio broadcast signal. 7. A first mixing circuit for mixing a television broadcast signal and a first frequency signal obtained from a first local oscillator circuit to output a television intermediate frequency signal, a radio broadcast signal and a second local portion. Second obtained from oscillator circuit
Second mixing circuit for outputting a radio intermediate frequency signal by mixing with the frequency signal of the above, and an intermediate for extracting an audio second intermediate frequency signal from the video intermediate frequency signal and the audio intermediate frequency signal included in the television intermediate frequency signal. A frequency filter circuit, a switch circuit for selectively outputting either the audio second intermediate frequency signal extracted from the intermediate frequency filter circuit or the radio intermediate frequency signal output from the second mixing circuit, and the switch An audio processing unit that processes an output signal of a circuit and outputs an audio signal. 8. The receiver according to claim 7, wherein the first and second local oscillator circuits are one oscillator circuit. 9. The first frequency signal is an oscillation signal output from the oscillation circuit, and the second frequency signal is an oscillation signal output from the oscillation circuit via a frequency divider. The receiver according to claim 8, wherein the receiver is obtained. 10. The second frequency signal is an oscillation signal output from the oscillation circuit, and the first frequency signal is the oscillation signal output from the oscillation circuit obtained via a multiplier. The receiver according to claim 8, characterized in that: