JP2003168992A - TV signal receiver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, when a cellular phone is used in the vicinity of a television signal receiver, a signal of the cellular phone is input as disturbance. <P>SOLUTION: A television signal receiver comprises an antenna 11; a lowpass filter 13 to which a signal of this antenna 11 is supplied and which passes a television signal; an amplifier 14 connected to this lowpass filter 13; a tuner part 15 connected to an output of this amplifier 14; and an output terminal 16 connected to this tuner part 15. A trap circuit 12 for obstructing a frequency to be used in the cellular phone is inserted between the antenna 11 and the lowpass filter 13. Thus, it is possible to obtain the television signal receiver which is not affected by the cellular phone. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television signal receiving device used near a mobile phone.

[0002]

2. Description of the Related Art A conventional television signal receiving apparatus will be described below. As shown in FIG. 5, a conventional television signal receiving apparatus is provided with an antenna 1, a low-pass filter 2 connected to the antenna 1, an amplifier 3 connected to the low-pass filter 2, and an output of the amplifier 3. The tuner unit 4 and the output terminal 5 to which the output of the tuner unit 4 is connected. The mobile phone 6 was used at a position apart from the television signal receiving device. Therefore, the signal of the mobile phone 6 does not adversely affect the television signal receiving device and the image of the television signal receiving device is not disturbed.

[0003]

However, in such a conventional structure, when the mobile phone 6 is used near the television signal receiving device, the signal of the mobile phone 6 adversely affects the television signal receiving device. However, there is a problem that the image of the television signal receiving device is disturbed.

The present invention has been made to solve the above problems, and an object thereof is to provide a television signal receiving apparatus which is not affected by a mobile phone.

[0005]

In order to achieve this object, a television signal receiving apparatus according to the present invention has a trap circuit for blocking a frequency used in a portable telephone inserted between an antenna and a low pass filter. Is.

As a result, the influence on the television signal receiving device of the mobile phone can be eliminated.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a television signal receiving apparatus which is used in the vicinity of a mobile telephone and receives a television signal of a frequency lower than the frequency used by the mobile telephone. The television signal receiving device includes an antenna, a low-pass filter which is supplied with a signal from the antenna and passes the television signal, an amplifier to which an output of the low-pass filter is connected, and a tuner to which an output of the amplifier is connected. Section and an output terminal to which an output of the tuner section is connected, and a television signal receiving device in which a trap circuit for blocking a frequency used in the mobile phone is inserted between the antenna and the low-pass filter. So, because the trap circuit that blocks the frequency of the mobile phone is inserted in this way, the influence of the mobile phone will Not be given to the location. Therefore, the image of the television signal receiving device is not disturbed.

Since a low-pass filter is provided at the input of the amplifier, stable amplification is possible without being directly affected by the trap circuit.

The trap circuit of the invention described in claim 2 is
The television signal receiving device according to claim 1 in which the inductor and the capacitor are connected in series, and the price can be reduced because it is a simple circuit in which the inductor and the capacitor are connected in series.

The trap circuit of the invention described in claim 3 is
The television signal receiving device according to claim 1, wherein the inductor and the capacitor are connected in parallel, and the television signal receiving device is configured by a parallel circuit. Therefore, it is difficult to be influenced by the ground and a trap circuit having stable characteristics can be formed.

Since the impedance can be increased in this case, the trap circuit can be inserted after the low-pass filter.

According to a fourth aspect of the present invention, the trap circuit and the low-pass filter are formed on a multilayer substrate, and a first inductor forming the trap circuit and a second inductor forming the low-pass filter are provided. The television signal receiving device according to claim 1, wherein a ground plane is provided between the trap circuit and the low-pass filter, and the ground plane is provided between the trap circuit and the low-pass filter. The characteristics can be obtained.

The invention according to claim 5 is the television signal receiving apparatus according to claim 4, wherein the first inductor forming the trap circuit is formed by a chip component, and the chip component is reflow-soldered. Since the chip parts are used, the accuracy of the inductance can be increased and the accurate trap circuit frequency can be set. Further, since the inductor formed by the chip component has a high Q, a trap having a good attenuation characteristic can be obtained. Therefore, the frequency of the mobile phone can be surely blocked.

According to a sixth aspect of the present invention, a pattern inductor for adjustment is provided in series with the first inductor forming the trap circuit, and the pattern inductor can be adjusted by laser trimming. Since this is a television signal receiving device and the inductor can be adjusted, an accurate trap frequency can be set. Therefore, the frequency of the mobile phone can be surely blocked.

The antenna according to claim 7 is the television signal receiving device according to claim 1, which is a tuning antenna, and can improve the receiving sensitivity.

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram of a television signal receiving apparatus according to Embodiment 1 of the present invention. In this embodiment, 11 is an antenna, and a tuning antenna is used in this embodiment. Therefore, the receiving sensitivity can be improved. Reference numeral 12 is a trap circuit connected to the tuning antenna 11.

The trap circuit 12 removes the frequency used in the mobile phone 17, and is formed of a series circuit of an inductor and a capacitor in the present embodiment. Since the trap circuit 12 is formed of a series circuit, Q can be increased by increasing the capacitance of the capacitor and decreasing the value of the inductor. Therefore, by using the chip capacitor as the capacitor and the pattern inductance as the inductor, the miniaturization can be realized.

The trap circuit 12 can also be formed by a parallel circuit of an inductor and a capacitor. In this case, since it is formed by a parallel circuit, Q can be increased by decreasing the capacitance of the capacitor and increasing the value of the inductor. Further, since it is a parallel circuit, it is insulated from the ground, and stable performance that is not affected by the ground wiring can be obtained. Further, the position of the low pass filter 13 can be exchanged.

Reference numeral 13 is a low-pass filter connected to the output of the trap circuit 12, which cuts off frequencies above 900 MHz in order to remove frequencies used in the mobile phone 17. The output of this low-pass filter is connected to the tuner section 15 via the amplifier 14. The output of the tuner unit 15 is connected to the output terminal 16. Reference numeral 17 is a mobile phone that transmits and receives in the 900 MHz band, or a mobile phone that transmits and receives in the 1.5 MHz band.

Here, as the tuner unit 15, the trap circuit 12, the low-pass filter 13, and the amplifier 14 may be included in the tuner unit and housed in a metal shield case.

FIG. 2 shows the pass characteristics of the trap circuit 12 and the low-pass filter 13, with the horizontal axis 18 representing the frequency (MH).
z), and the vertical axis 19 is the output level output from the low-pass filter 13. Reference numeral 20 denotes a passage area of a television signal, which is approximately 800 MHz. Therefore, this 800MH
Low-pass filter 13 for blocking frequencies above z
Has been inserted, and this characteristic is shown in 21.

If only the low-pass filter 13 is used, for example, the frequency 22 of the mobile phone 17 is 900 MH.
z, and 22a of characteristic 21 is its level. With this low-pass filter 13 alone, its level is characteristic 21.
As shown by the dotted line in, there is not much attenuation. Therefore, when the mobile phone 17 is in the vicinity, the signal of the mobile phone 17 is input to the television signal receiving device and the screen is disturbed.
Therefore, the trap frequency is about 900 MHz (or 1.5
2) by providing the trap circuit 12 of (MHz)
4 has a trap characteristic as shown in FIG. Therefore, the characteristic 25 is shown by the solid line as a whole, and even if the mobile phone 17 is used in the vicinity, the frequency of the mobile phone 17 does not affect the television signal receiving device.

The trap circuit 12 is a simple circuit composed of a series circuit of an inductor and a capacitor.
Since the low-pass filter 13 is provided between the trap circuit 12 and the amplifier 14, the input impedance of the amplifier 14 can be stably amplified without being affected by the trap circuit 12. is there.

FIG. 3 is a cross-sectional view of essential parts of the trap circuit 12 and the low-pass filter 13 formed on the multilayer substrate 30. In FIG. 3, a chip inductor 32 forming the trap circuit 12 and a chip capacitor 33 forming the low pass filter 13 are mounted on the component surface 31 of the multilayer substrate 30. Further, 34 is a pattern inductor that constitutes the low-pass filter 13, and is incorporated in the third layer. A ground plane 35 is inserted between the pattern inductor 34 and the chip inductor 32 of the trap circuit 12. Therefore, the chip inductor 3
2 and the pattern inductor 34 can obtain independent filter characteristics without interfering with each other. Further, although the chip inductor 32 is used in the trap circuit 12, a pattern inductor may be used.

FIG. 4 shows an example thereof. That is, a series connection body of the adjustment pattern inductor 38, the pattern inductor 39, and the capacitor 40 is connected between the signal line 36 connected to the tuning antenna 11 and the ground 37. An accurate inductance can be obtained by adjusting the adjusting portion 38a of the adjusting pattern inductor 38 by laser trimming. This allows the trap frequency to match the frequency of the mobile phone 17.

The chip parts 32 and 33 are reflow soldered. This is due to the self-alignment effect of using reflow solder,
Is to fix it in a fixed position. Therefore, the value of the pattern inductance in the vicinity of the chip parts 32 and 33 becomes constant, and stable performance can be obtained.

[0027]

As described above, according to the present invention, since the trap circuit for blocking the frequency of the mobile phone is inserted between the tuning antenna and the low-pass filter, the influence of the mobile phone on the television signal receiving apparatus. Given that, the image will not be disturbed.

Since a low-pass filter is provided at the input of the amplifier, stable amplification is possible without being directly affected by the trap circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of a television signal receiving device used near a mobile phone according to an embodiment of the present invention.

FIG. 2 is a characteristic diagram of a filter forming the television signal receiving device.

FIG. 3 is a sectional view of the main part in the vicinity of the filter.

FIG. 4 is a circuit diagram of the same trap circuit.

FIG. 5 is a block diagram of a conventional television signal receiving device and a mobile phone.

[Explanation of symbols]

11 Tuning antenna 12 Trap circuit 13 Low-pass filter 14 Amplifier 15 Tuner section 16 output terminals 17 mobile phones

Claims (7)

[Claims] 1. Used in the vicinity of a mobile phone,
A television signal receiving device for receiving a television signal of a frequency lower than the frequency used by the mobile phone, wherein the television signal receiving device is provided with an antenna and a low-pass signal that is supplied with the antenna signal and allows the television signal to pass. A filter, an amplifier to which the output of the low-pass filter is connected, a tuner section to which the output of the amplifier is connected, and an output terminal to which the output of the tuner section is supplied, and the antenna and the low-pass filter A television signal receiving device in which a trap circuit for blocking frequencies used in the mobile phone is inserted. 2. The television signal receiving apparatus according to claim 1, wherein the trap circuit has an inductor and a capacitor connected in series. 3. The television signal receiving apparatus according to claim 1, wherein the trap circuit has an inductor and a capacitor connected in parallel. 4. The trap circuit and the low-pass filter are formed on a multi-layer substrate, and a ground plane is provided between a first inductor forming the trap circuit and a second inductor forming the low-pass filter. The television signal receiving apparatus according to claim 1, further comprising: 5. The television signal receiving apparatus according to claim 4, wherein the first inductor forming the trap circuit is formed of a chip component, and the chip component is reflow-soldered. 6. The television signal receiving apparatus according to claim 4, wherein a pattern inductor for adjustment is provided in series with the first inductor forming the trap circuit, and the pattern inductor can be adjusted by laser trimming. 7. The television signal receiving apparatus according to claim 1, wherein the antenna is a tuning antenna.