JPH11112375A - Television signal receiving tuner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate switching between a TV and an FM signal and to make the tuner small-sized by putting a UHF tuner part, a VHF tuner part, respective input terminals, and a signal switching circuit which inputs the TV or FM transmit signal to the VHF tuner part in a casing and connecting a TV signal input terminal to the UHF tuner part. SOLUTION: A UHF/VHF mixed TV signal is inputted from a TV signal input terminal 2 and the FM signal is inputted from an FM broadcast signal input terminal 3. The UHFTV signal is inputted to the UHF tuner part 5 with low loss without passing through the switching circuit. The signal switching circuit 4 selects the input terminal 2 or 3 and outputs the selected signal to the VHF tuner part 6. The VHF tuner part 6 switches its inside to a state suitable for the reception of a high-band VHF signal or low-band VHF signal (including the FM signal) and inputs the selected signal. A band switching voltage generating circuit 7 supplies four kinds of voltage needed for the switching. The circuit is simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a television signal receiving tuner capable of receiving an FM broadcast signal.

[0002]

2. Description of the Related Art Conventionally, when receiving a television signal and an FM broadcast signal, a UHF tuner and a VHF tuner are used.
A signal switching circuit is connected to a television signal receiving tuner having a television signal receiving circuit, and either the television signal or the FM broadcast signal is input to the television signal tuner by the signal switching circuit, and the television signal is received. In the tuner, a UHF band television signal is received by a UHF tuner section, and a VHF band television signal or FM signal is received.
Broadcast signals are received by the VHF tuner.

A conventional configuration will be described with reference to FIG. FIG.
In the above, the signal switching circuit 51 is provided with a television signal input terminal 52 for receiving a UHF band television signal and a VHF band television signal, and an FM broadcast signal input terminal 53 for receiving an FM broadcast signal. I have. Then, either the television signal or the FM broadcast signal is selected by the switching signal input to the switching terminal 54 and is input from the output terminal 55 to the television signal receiving tuner 56.

Hereinafter, the signal switching circuit 51 will be described. A high-pass filter 57 and a first switch diode 58 are connected in series between the television signal input terminal 52 and the output terminal 55.
7 and the first switch diode 58 are connected to ground via a third switch diode 59. On the other hand, a low-pass filter 60 and a second switch diode 61 are connected in series between the FM broadcast signal input terminal 53 and the output terminal 55, and the high-pass filter 60 and the second switch diode 61 are connected in series. Is connected to ground via a fourth switch diode 62.

The cathode of the first switch diode 58 and the anode of the second switch diode 61 are directly connected to each other. And this connection point is the output terminal 55
And a switching terminal 54 via a choke inductor 63. Further, the anode of the first switch diode 58 is connected to the power supply B via the resistor 64, and the cathode of the second switch diode 61 is connected.
Is connected to ground via a resistor 65. The anode of the third switch diode 59 and the cathode of the fourth switch diode 62 are connected to the switching terminal 5.
4 and the cathode of the third switch diode 59.
And the anode of the fourth switch diode 62 is connected to the power supply B via the resistor 66.

When an FM broadcast signal is received, the first switch diode 58 is turned off and the second switch diode 61 is turned on by the high-level switching voltage supplied to the switching terminal 54. State. At this time, the third switch diode 59 is turned on and the fourth switch diode 62 is turned off, so that the television signal (UHF band) input to the television signal input terminal 52 is input. And television signals in the VHF band) do not appear at the output terminal 55,
Only the FM broadcast signal input to the broadcast signal input terminal 53 appears at the output terminal 55. On the other hand, when a television signal is received, a low-level switching voltage (or 0 volt) is supplied to the switching terminal 54, so that the first switch diode 58 and the fourth switch diode 6 are supplied.
2 is electrically connected to the second switch diode 61.
And the third switch diode 59 become non-conductive, and only the television signal is input to the television signal receiving tuner 56. Here, the switching voltage supplied to the switching terminal 54 is supplied from a control unit (not shown) such as a microcomputer provided in the television set, for example.

The television signal receiving tuner 56 has a U
An input terminal 6 to which a HF band television signal, a VHF band television signal, and an FM broadcast signal are commonly input.
7, a duplexer 68, a UHF tuner section 69, a VHF tuner section 70, a band switching circuit 71, and the like.
The demultiplexer 68 normally has a high-pass filter and a low-pass filter, and converts a UHF band television signal of the television signal or FM broadcast signal input to the input terminal 67 via the high-pass filter to the UHF filter. Na 69
In addition, the television signal and the FM broadcast signal in the VHF band are divided and input to a VHF tuner 70 via a low-pass filter. Here, although detailed description is omitted, V
The HF tuner unit 70 can switch between a high-band television signal, a low-band television signal, and an FM broadcast signal and receive the same. Then, a UHF band television signal, a VHF band high band television signal, a VHF band low band television signal and an FM broadcast signal are received by the band switching voltage from the band switching circuit 71. .

[0008] That is, the band switching circuit 71, based on the control signal from the television set, UB, HB, L
The three band switching voltages B are output. The band switching voltage UB is supplied to the UHF tuner 69, and the band switching voltages HB and LB are supplied to the VHF tuner 70. The band switching voltage UB is output when a television signal in the UHF band is received.
The tuner 69 is in the operating state. The band switching voltage HB is output when a high-band television signal is received, whereby the VHF tuner 70 enters a high-band television signal reception state. Further, the band switching voltage LB is output when a low-band television signal or FM broadcast signal is received,
As a result, the VHF tuner 70 enters a state of receiving a low-band television signal or FM broadcast signal. Then, as described above, either the television signal or the FM broadcast signal is inputted to the television signal receiving tuner 56 by the switching voltage supplied to the switching terminal 54 of the signal switching circuit 51.

[0009]

However, in the above configuration, in order to receive the FM broadcast signal, a signal switching circuit 51 is prepared in addition to the television signal receiving tuner 56, and this signal switching circuit is provided. Therefore, it is necessary to select either the television signal or the FM broadcast signal in advance and input the signal to the television signal tuner 56. for that reason,
For example, when configuring a card-type tuner to be mounted on a personal computer (personal computer), a television signal receiving tuner 56 is mounted on a printed circuit board for the card and this printed circuit board is mounted. In this case, it is necessary to configure the signal switching circuit 51, and also in this case, since the signal switching circuit 51 needs to be shielded, a large area is required for the printed circuit board, and the pudding substrate becomes large. there were.

Conventionally, the television signal receiving tuner 56 is provided with a duplexer 68 for separating a UHF band television signal and a VHF band television signal. The signal passes through the high-pass filter 57 and the low-pass filter 60 of the signal switching circuit 51 and the high-pass filter or the low-pass filter of the duplexer 68, thereby increasing the signal loss.

Further, the signal switching circuit 51 includes a band switching circuit 7 of the television signal receiving tuner 56.
Since a switching voltage different from the band switching voltage from 0, for example, a microcomputer is supplied,
The switching voltage of the system was used, and the wiring was complicated. And since noise components such as clock signals are leaked and superimposed on the switching voltage from the microcomputer,
This noise component is transmitted to the television signal input terminal 52 or FM
There is a problem in that the signal leaks to the outside through the broadcast signal input terminal 53 and causes interference to other television signal receiving tuners, or the signal is input to the own television signal tuner 56 to cause interference.

Further, when the lowest frequency of the UHF band television signal and the highest frequency of the VHF band television signal are close to each other, the splitter 68 converts the UHF band television signal and the VHF band television signal into the same. For example, when receiving a low frequency television signal in the UHF band, the VHF tuner unit 70 acts as a load and the input impedance at the input terminal 67 becomes a predetermined value (usually 75-degree). Problem). Therefore, the present invention solves the above-mentioned problems, reduces the size of a television signal receiving tuner capable of receiving an FM broadcast signal, reduces the loss of a television signal, and reduces the loss of a television signal to a UHF tuner or a VHF tuner. Can be input, simplify switching between television signals and FM broadcast signals, and
This is to suppress the occurrence of interference due to this switching.

[0013]

In order to solve the above-mentioned problems, a television signal receiving tuner according to the present invention comprises a UHF receiver.
Signal input terminal for inputting a television signal of a VHF band and a television signal of a VHF band, an FM broadcast signal input terminal for receiving an FM broadcast signal, a UHF tuner section, and a VHF tuner. And a signal switching circuit for inputting either the television signal input to the television signal input terminal or the FM broadcast signal input to the FM broadcast signal input terminal to the VHF tuner unit. And the television signal input terminal was connected to the UHF tuner section.

Further, the television signal receiving tuner of the present invention provides a band switching for outputting a first band switching voltage, a second band switching voltage, a third band switching voltage, and a fourth band switching voltage. A voltage generating circuit is provided in the housing, and when receiving a television signal in the UHF band, the first band switching voltage is set to the UHF band.
The second band switching voltage is supplied to the tuner section to make the UHF tuner section operative, and to receive the high band television signal in the VHF band.
The VHF tuner section is supplied to a tuner section to bring the VHF tuner section into an operation state capable of receiving the high band television signal, and the second band switching voltage is supplied to the signal switching circuit to supply the television signal to the television section. The television signal input to the television signal input terminal is transmitted to the VHF tuner.
When a low band television signal of a VHF band is input to the VHF tuner section, the third band switching voltage is supplied to the VHF tuner section to connect the VHF tuner section to the low band. And the television signal input terminal is supplied with the third band switching voltage to the signal switching circuit to convert the television signal input to the television signal input terminal into the VHF signal.
The third band switching voltage is supplied to the VHF tuner section when the FM broadcast signal is input to the tuner section and the VHF tuner section transmits the low band television signal. In the receivable operation state, the fourth band switching voltage is supplied to the signal switching circuit, and the F band input to the FM broadcast signal input terminal is
The M broadcast signal was input to the VHF tuner.

Further, in the television signal receiving tuner of the present invention, the television signal input terminal and the UHF tuner section are connected via a first switch diode, and are connected to the signal switching circuit. A second switch diode and a third switch diode, wherein the first switch diode is turned on by the first band switching voltage to switch the television signal to the first switch. An input to the UHF tuner section via a diode, the second switch diode is turned on by the second band switching voltage or the third band switching voltage, and the television signal is transmitted. Input to the VHF tuner via the second switch diode;
The third switch diode is turned on by the fourth band switching voltage, and the FM broadcast signal is transmitted to the VHF tuner via the third switch diode.
It was made to input to the part.

In the television signal receiving tuner of the present invention, the signal switching circuit includes a low-pass filter and one end between the television signal input terminal and the second switch diode. A fourth switch diode connected to the ground at a high frequency, and when receiving a UHF band television signal, the fourth switch diode is turned on by the fourth band switching voltage. The television signal input terminal was terminated by the low-pass filter and the fourth switch diode.

Further, in the television signal receiving tuner of the present invention, a high-pass filter is provided between the television signal input terminal and the first switch diode, and the low-pass filter and the high-pass filter are provided. Thus, a duplexer was configured.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a television signal receiving tuner according to the present invention will be described with reference to FIGS. First,
FIG. 1 shows a schematic configuration of a television signal receiving tuner 1 according to the present invention. The television signal receiving tuner 1 according to the present invention commonly uses a UHF band television signal and a VHF band television signal. It has a television signal input terminal 2 to be inputted and an FM broadcast signal input terminal 3 to which an FM broadcast signal is inputted, and a signal switching circuit 4 and a U
An HF tuner 5, a VHF tuner 6, and a band switching voltage generator 7 are provided. The signal switching circuit 4 is connected between the television signal input terminal 2 and the FM broadcast signal input terminal 3 and the VHF tuner 6, and the UHF tuner 5 is connected to the television signal input. The band switching voltage from the band switching voltage generating circuit 7 is supplied to the signal switching circuit 4, the UHF tuner unit 5, and the VHF tuner unit 6, and the television signal in the UHF band is supplied to the UHF tuner unit 5 by the VHF tuner unit 5. The VHF tuner section can receive a high band television signal of a band, a low band television signal of a VHF band, and an FM broadcast signal. This band switching voltage is generated based on a tuning signal from a tuning device (not shown) of the television set.

That is, when a UHF band television signal is received, the UHF tuner section 5 is activated by the band switching voltage, and the UHF band television signal from the television signal input terminal 2 is transmitted to the UHF tuner.
The VHF tuner section 6 is not supplied with a band switching voltage, and the VHF tuner section 6 is deactivated, and receives a high band television signal in the VHF band. When V is changed by the band switching voltage
The HF tuner 6 is set to a high-band television signal receiving state, and a VHF band television signal from the television signal input terminal 2 is input to the VHF tuner 6 via the signal switching circuit 4. On the other hand, UHF Chu
The UHF without applying the band switching voltage to the
The tuner section 5 is set to a non-operating state.

When a low-band television signal in the VHF band is received, V-band is changed by a band switching voltage.
The HF tuner 6 is set to a state for receiving a low band television signal, and a VHF band television signal from the television signal input terminal 2 is input to the VHF tuner 6 via the signal switching circuit 4. On the other hand, the UHF tuner section 5 is supplied with the UH
The F tuner unit 5 is set to a non-operating state. Further, when receiving an FM broadcast signal, VH is set by a band switching voltage.
The F tuner unit 6 is set to a receiving state of a low-band television signal, and the FM signal from the FM broadcast signal input terminal 3 is input.
The broadcast signal is input to the VHF tuner section 6 via the signal switching circuit 4, while the UHF tuner section 5 is deactivated by not applying a band switching voltage to the UHF tuner section 5. Like that.

Therefore, only the television signal receiving tuner 1 of the present invention is used to transmit a UHF band television signal, a VHF band high band television signal, a VHF band low band television signal, and an FM broadcast signal. Can be received separately for each reception band (band). Further, since the signal switching circuit 4 for switching between the television signal and the FM broadcast signal is provided in the television signal receiving tuner 1, the overall size can be reduced. Further, since the switching of each band can be performed only by the band switching voltage from the band switching voltage generating circuit 7, the configuration is simplified.

Hereinafter, the configuration of the signal switching circuit 4 and its peripheral circuits will be described in detail with reference to FIG. First, a television signal input terminal 2 and a UHF tuner 5
A high-pass filter 8 composed of an inductor 8a and a capacitor 8b and a first switch diode 9 are sequentially connected in series. On the other hand, a low-pass filter 1 comprising an inductor 8a and a capacitor 10a is provided between the television signal input terminal 2 and the VHF tuner unit 6.
0, a parallel induction M-type high-pass filter 11 including an inductor 11a, a capacitor 11b, and an inductor 11c, and a second switch diode 12 are sequentially connected in series. Accordingly, the duplexer 13 is constituted by the high-pass filter 8 and the low-pass filter 10, and the inductor 8a is used for both the high-pass filter 8 and the low-pass filter 10.

A third switch diode 14 is connected between the FM broadcast signal input terminal 3 and the VHF tuner 6. The cathode of the second switch diode 12 and the cathode of the third switch diode 14 are directly connected to the VHF tuner section 6 and to the ground via a resistor 15. ing. The cathode of the fourth switch diode 16 is connected to the anode of the second switch diode 12, and the anode of the fourth switch diode 16 is connected to the DC blocking capacitor 17. It is connected to the ground through. The anode of the fifth switch diode 18 is also connected to the anode of the third switch diode 14, and the anode of the fifth switch diode 18 is connected to the DC blocking capacitor 19. Connected to the ground via

The cathode of the first switch diode 9 is connected to ground via a resistor 20, and the anode of the second switch diode 12 and the fourth switch diode 16 are connected. The connection point with the cathode is connected to the ground via the resistor 21, and the anode of the fifth switch diode 18 is connected to the ground via the resistor 22.

The band switching voltage generating circuit 7 has four output terminals BS1, BS2, BS3 and BS4, and applies a band switching voltage to these output terminals in response to a tuning signal from a tuning device of a television receiver (not shown). Occur. In the present invention, when a television signal in the UHF band is received (referred to as UHF mode), a first band switching voltage UB is generated at a first output terminal BS1, and a fourth band switching voltage UB is generated at a fourth output terminal BS4. When a high band television signal of VHF is received (referred to as VH mode), a second band switching voltage HB is generated only at the second output terminal BS2.
When a low-band television signal of VHF is received (referred to as VL mode), a third band switching voltage LB is generated only at the third output terminal BS3. When an FM broadcast signal is received (referred to as FM mode), a third band switching voltage LB is generated at a third output terminal BS3, and a fourth band switching voltage FB is generated at a fourth output terminal BS4. Is set to occur. This state is shown in FIG. 3, in which MD indicates each reception mode, and Hi indicates each band switching voltage UB, HB, V.
L and FB indicate that they are at a high level (for example, 5 volts), and Lo indicates that a band switching voltage is not generated and are at a low level (for example, 0 volts).

Then, the first band switching voltage UB from the first output terminal BS1 is supplied to the UHF tuner 5, so that the UHF tuner unit 5 is in the operating state (receivable state). Further, the second band switching voltage HB from the second output terminal BS2 and the third band switching voltage LB from the third output terminal BS3 are supplied to the VHF tuner section 6, thereby the VHF tuner. The unit 6 is ready to receive a high-band television signal or a low-band television signal. Note that VH
The tuning frequency range of the tuning circuit and the like (not shown) included in the VHF tuner section 6 is expanded in the F tuner section 6 so that it can receive an FM broadcast signal.

Further, the first band switching voltage UB from the first output terminal BS1 of the band switching voltage generating circuit 7 is supplied to the anode of the first switch diode 9 via the resistor 23, A third band switching voltage LB from the third output terminal BS3 is connected via a resistor 24 to a connection point between the anode of the second switch diode 12 and the cathode of the fourth switch diode 16. It is also supplied to the anode of the fifth switch diode 18 via the resistor 25. Further, a fourth output terminal BS
4 is supplied to the anode of the fourth switch diode 16 via a resistor 26, and via a choke inductor 27 connected in series with the resistor 26. Third switch diode 14
Is connected to the node of the fifth switch diode 18 and the cathode of the fifth switch diode 18. The second band switching voltage VH from the second output terminal BS2 is also supplied to the resistors 24 and 25 via the sixth switch diode 28. −
A switch diode for switching a band in a tuning circuit (not shown) formed in the VHF tuner unit 6 may be used as the node 28.

In the UHF mode, the first switch diode 9 is turned on by the first band switching voltage UB from the first output terminal BS1, and is input to the television signal input terminal 2. The UHF band television signal that has passed through the high-pass filter 8 is input to the UHF tuner unit 5 via the first switch diode 9 among the television signals being transmitted. At this time, the fourth band switching voltage FB is also applied to the fourth output terminal BS4.
Is output, the resistor 26 and the fourth switch diode 1 are applied by the fourth band switching voltage FB.
6. A current flows through the resistor 21 to make the fourth switch diode 16 conductive. In this case, the fourth output terminal B
Since the current flows through the resistor 26, the choke inductor 27, the third switch diode 14, and the resistor 15 by the fourth band switching voltage FB from S4, the third switch diode 14 becomes conductive. The second switch diode 12 is turned off (the voltage of the anode of the second switch diode 12 is reduced by the voltage drop of the fourth switch diode 16). (Less than the voltage of the cathode of the cathode 14).

Therefore, the television signal input terminal 2 and V
The signal path connecting to the HF tuner section 6 is cut off by the second switch diode 12, and the television signal in the VHF band via the low-pass filter 10 is terminated by the fourth switch diode 16. . Therefore, the impedance between the television signal input terminal 2 and the UHF tuner unit 5 can be maintained at a substantially predetermined value, for example, 75 ohms. Although the third switch diode 14 becomes conductive, neither the second band switching voltage HB nor the third LB is supplied to the VHF tuner 6, so that the FM broadcast signal is received. There is no danger.

Next, in the VH mode, the second band switching voltage HB from the second output terminal BS2 is VHF.
The VHF tuner 6 is supplied to the tuner 6 so that the VHF tuner 6 can receive high-band television signals, and the resistor 2 is connected via the sixth switch diode 28.
4. A current flows through the resistor 15 of the second switch diode 12, and the second switch diode 12 becomes conductive.
Further, the fourth switch diode 16 is in a non-conductive state since it is in a reverse bias state. At this time, the second band switching voltage HB is also supplied to the anode of the fifth switch diode 18 via the resistor 25, and the fifth switch diode 18 becomes conductive.
Since the resistance values of the resistors 22 and 25 are set so that the voltage of the anode of the third switch diode 14 is lower than the voltage drop of the resistor 15, the third switch diode is set.
The node 14 is turned off. Since the first band switching voltage UB is not generated, the first switch diode 9 is in a non-conductive state, and the UHF tuner unit 5 is inoperable.

The television signal in the VHF band among the television signals input to the television signal input terminal 2 is transmitted through the second switch diode 12 to the VHF band.
The signal is input to a tuner unit 6, where a high-band television signal is received. The FM broadcast signal from the FM broadcast signal input terminal 3 is supplied to a third switch diode 14.
Are not input to the VHF tuner unit 6 because of the non-communication state.

Next, in the VL mode, the VHF tube
And the first switch diode 9 through the fifth switch diode 18 are in the conductive state and the non-conductive state are in the VH mode.
The same as in the case of C. Therefore, the television signal from the television signal input terminal 2 is input to the VHF tuner unit 6, and the low band television signal is received.

Finally, in the FM mode, the third switch diode 14 is turned on by the fourth band switching voltage FB from the fourth output terminal BS4 and the fifth switch diode is turned on. The node 18 is reverse biased and becomes non-conductive. Also, the fourth band switching voltage F
By B, the fourth switch diode 16 is turned on, but the second switch diode 12 is turned off. Further, a third band switching voltage LB is generated at the third output terminal BS3, and the VHF tuner 6 is in a state of receiving a low-band television signal.
Accordingly, the television signal from the television signal input terminal 2 is blocked by the second switch diode 12 in a non-conductive state and is not input to the VHF tuner unit 6, but instead is input to the FM broadcast signal input terminal. Only the FM broadcast signal from 3 is input to the VHF tuner section 6 and received.

As described above, the first to fourth band switching voltages UB to FB for conducting the first to fifth switch diodes 12 to 18 are all band switching voltage generating circuits. 7 and no unnecessary noise components are superimposed on these band switching voltages. Therefore, even if the band switching voltages are supplied to the first to fifth switch diodes 9 to 18, No noise component is radiated from the signal input terminal 2 or the FM broadcast signal input terminal 3 to the outside. Therefore, it does not interfere with other television signal receiving tuners. Further, the UHF tuner 5 and the VHF tuner 6
Since no noise component is input, no interference occurs in the television signal receiving tuner 1. Further, since the duplexer 13 is provided at the television signal input terminal 2, it is not necessary to provide a high-pass filter or a low-pass filter in the UHF tuner section 5 and the VHF tuner section 6, respectively. Signal loss is reduced.

[0035]

As described above, the television signal receiving tuner of the present invention comprises a UHF tuner section and a VHF tuner.
And a television signal input to a television signal input terminal or an F signal input to an FM broadcast signal input terminal.
A signal switching circuit for inputting any one of the M broadcast signals to the VHF tuner is provided in the housing, and the television signal input terminal is connected to the UHF tuner. UHF band television signal and VHF band high band television signal and VH
An F-band low-band television signal and an FM broadcast signal can be received separately for each reception band (band). Therefore, there is no need to separately provide a signal switching circuit for switching between the television signal and the FM broadcast signal, so that the size can be reduced.

Further, the television signal receiving tuner of the present invention includes a band switching voltage generating circuit for outputting a band switching voltage in a housing, and performs first band switching when receiving a UHF band television signal. UH in voltage
When the F tuner is in the operating state and the VHF band high band television signal is received, the VHF tuner is set in the operating state capable of receiving the high band television signal with the second band switching voltage. When a television signal is input to the VHF tuner section at the second band switching voltage and a low band television signal of the VHF band is received, the VHF tuner section is supplied at the third band switching voltage. Is set to an operation state in which a low-band television signal can be received, and a television signal is input to a VHF tuner at a third band switching voltage, and a third band is received when an FM broadcast signal is received. VH at switching voltage
The F-tuner is set to an operation state capable of receiving a low-band television signal, and the FM broadcast signal is input to the VHF tuner at the fourth band-switching voltage. The television signal and the FM broadcast signal can be switched only by the band switching voltage from the circuit. Therefore, the configuration for band switching is simplified.

Also, in the television signal receiving tuner of the present invention, a television signal input terminal and a UHF tuner are connected via a first switch diode, and a second signal switching circuit is connected to a signal switching circuit. A switch diode and a third switch diode, wherein the first switch diode is made conductive by a first band switching voltage, and a television signal is transmitted through the first switch diode to the UHF. Chu
The second switch diode is turned on by the second band switching voltage or the third band switching voltage, and the television signal is transmitted to the VHF tuner via the second switch diode. The third switch diode is turned on by the fourth band switching voltage and the FM broadcast signal is transmitted to the third switch diode.
Input to the VHF tuner section via the switch, so that even if the first switch diode to the third switch diode are turned on by these band switching voltages, the band switching voltage is not changed. Since unnecessary noise components are not superimposed, no noise components are radiated from the television signal input terminal or the FM broadcast signal input terminal to the outside via the first to third switch diodes. Therefore, another television signal receiving tube is used.
Do not disturb na. In addition, UHF tuner and VH
Since no noise component is input to the F tuner section, no interference occurs in the television signal receiving tuner.

Further, in the television signal receiving tuner of the present invention, the signal switching circuit has a low-pass filter between the television signal input terminal and the second switch diode and one end grounded for high frequency. And a fourth switch diode connected to the terminal. When a television signal in the UHF band is received, the fourth switch diode is turned on by a fourth band switching voltage so that a television signal input terminal is provided. Is terminated by a low-pass filter and a fourth switch diode, so that in the UHF band, impedance matching between the television signal input terminal and the UHF tuner can be obtained.

In the television signal receiving tuner of the present invention, a high-pass filter is provided between the television signal input terminal and the first switch diode, and the signal is split by the low-pass filter and the high-pass filter. Since the UHF tuner and the VHF tuner do not need to be provided with a high-pass filter and a low-pass filter respectively, the loss of the television signal is reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a television signal receiving tuner of the present invention.

FIG. 2 is a detailed circuit diagram of a signal switching circuit in the television signal receiving tuner of the present invention.

FIG. 3 is a diagram showing a state of generation of a band switching voltage in the television signal receiving tuner of the present invention.

FIG. 4 is a configuration diagram for receiving a television signal and an FM broadcast signal using a conventional television signal receiving tuner.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 television signal receiving tuner 2 television signal input terminal 3 FM broadcast signal input terminal 4 signal switching circuit 5 UHF tuner section 6 VHF tuner section 7 band switching voltage generating circuit 8 high-pass filter 8a inductor 8b capacitor 9 First switch diode 10 low pass filter 10a capacitor 11 induction M type high pass filter 11a, 11b inductor 11c capacitor 12 second switch diode 13 duplexer 14 third switch diode 15, 20, 21, 22, 23, 24, 25, 26 Resistance 16 Fourth switch diode 17, 19 DC blocking capacitor 18 Fifth switch diode 27 Choke inductor 28 Sixth switch diode BS1, BS2 , BS3, BS4 band switching Of the output terminal UB first of the band switching voltage HB second band switching voltage LB third band switching voltage FB fourth band switching voltage

Claims (5)

[Claims] 1. A UHF band television signal and VH
A television signal input terminal to which an F-band television signal is input; an FM broadcast signal input terminal to which an FM broadcast signal is input; a UHF tuner;
A tuner, a signal switching circuit for inputting either a television signal input to the television signal input terminal or an FM broadcast signal input to the FM broadcast signal input terminal to the VHF tuner; In the housing,
A television signal receiving tuner, wherein the television signal input terminal is connected to the UHF tuner. 2. A UHF band comprising a band switching voltage generating circuit for outputting a first band switching voltage, a second band switching voltage, a third band switching voltage, and a fourth band switching voltage in the housing. When the television signal is received, the first band switching voltage is supplied to the UHF tuner to make the UHF tuner operative, thereby receiving a VHF band high band television signal. When the second band switching voltage is supplied to the VHF tuner section, the VHF tuner section is brought into an operation state capable of receiving the high band television signal, and the second band switching voltage is supplied to the VHF tuner section. A voltage is supplied to the signal switching circuit to convert the television signal input to the television signal input terminal into the VHF signal.
The third band switching voltage is supplied to the VHF tuner section when it is inputted to the tuner section and the low band television signal of the VHF band is received.
The television set is set to an operation state capable of receiving the low-band television signal, and supplies the third band switching voltage to the signal switching circuit to input the television signal to the television signal input terminal. When a signal is input to the VHF tuner unit and the FM broadcast signal is received, the third band switching voltage is applied to the VHF tuner.
To supply the VHF tuner to an operation state capable of receiving the low-band television signal, and to supply the fourth band switching voltage to the signal switching circuit to provide the FM broadcast. 2. A television signal receiving tuner according to claim 1, wherein an FM broadcast signal input to a signal input terminal is input to said VHF tuner. 3. The television signal input terminal and the U signal
An HF tuner is connected via a first switch diode, the signal switching circuit includes a second switch diode and a third switch diode, and the first band switching is performed. The first switch diode is turned on by a voltage, and the television signal is input to the UHF tuner via the first switch diode, and the second band switching voltage or the The second switch diode is driven by a third band switching voltage.
The television signal is input to the VHF tuner via the second switch diode, and the third switch diode is rendered conductive by the fourth band switching voltage. State and the FM broadcast signal is transmitted to the VHF through the third switch diode.
3. The television signal receiving tuner according to claim 2, wherein the signal is inputted to a tuner section. A fourth switch having a low-pass filter connected between the television signal input terminal and the second switch diode and having one end connected to the ground at high frequency. Diode and UHF
When receiving a television signal of a band, the fourth switch diode is turned on by the fourth band switching voltage, and the television signal input terminal is connected to the low-pass filter and the fourth switch diode. 4. A television signal receiving tuner according to claim 3, wherein said television signal receiving tuner is terminated with a terminal. 5. A high-pass filter is provided between the television signal input terminal and the first switch diode, and a duplexer is constituted by the low-pass filter and the high-pass filter. The television signal receiving tuner according to claim 4, wherein