Television tuner

A TV tuner and capacitor technology, applied in TV, color TV, color TV parts, etc., can solve the problems of difficulty in changing to the most suitable frequency band, insufficient suppression effect of VHF low frequency band, etc., and achieve improved frequency selection characteristics Effect

Inactive Publication Date: 2009-08-19
ALPS ALPINE CO LTD
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0012] However, although the TV tuner described in Patent Document 1 can suppress the VHF frequency band, since the series resonance frequency of the capacitance / inductance constituting the HPF is located in the UHF frequency band, the VHF low frequency band during VHF high frequency reception Insufficient inhibitory effect
[0013] In addition, although the TV tuner described in Patent Document 2 can obtain the suppression effect of the VHF low frequency band, when receiving the UHF frequency band, there is no attenuation member on the low frequency side, and the suppression effect of the VHF low frequency band is insufficient.
In addition, since the inductance constitutes the UHF antenna tuning circuit, the priority is given to ensuring the ANT selection characteristic, so it is difficult to obtain the most suitable frequency band for the VHF frequency band, and the improvement of the selection characteristic of the VHF frequency band is desired

Method used

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Embodiment Construction

[0034] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0035] figure 1 It is a circuit configuration diagram of the TV tuner according to the embodiment of the present invention. Also, for Figure 8 The same parts of the shown TV tuner are given the same symbols to avoid redundant description. In the TV tuner of the present embodiment, ground circuits (11, 12) are formed between the input part of the VHF tuning circuit 2 and the ground through inductance, and a switch circuit for switching the inductance value of the ground circuits (11, 12) is connected. (D1, D2). Furthermore, the switch circuit (D1, D2) has the HPF function of suppressing the signal on the low frequency side for the reception frequency when receiving the UHF / VHF high frequency band. In addition, when receiving the VHF low frequency band, capacitors (14, 15) are arranged so as to have a function of suppressing signals on the high frequency s...

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Abstract

In the television tuner, between an input part of a VHF tuning circuit 2 and the ground, inductor grounded circuits that ground via inductors are formed. Further, to the inductor grounded circuit, a switch diode D2 that operates in synchronization with a VHF high band reception operation and a switch diode D1 that turns on / off at a reception of a certain channel are disposed in parallel. By the on / off operation of the switch diodes D1 and D2, at a reception of UHF / VHF high band, a HPF for suppressing a signal in a low band side to a reception frequency is formed, and at a reception of VHF low band, a LPF that suppresses a signal in a high band side to a reception frequency is formed.

Description

technical field [0001] The present invention relates to a television tuner for selectively receiving a first frequency band and a second frequency band. Background technique [0002] Conventionally, a TV tuner has been proposed that utilizes the attenuation characteristics on the low-frequency side of a high-pass filter (HPF) to attenuate a signal in the VHF band during reception in the UHF band, thereby obtaining a suppression effect in the VHF band (for example, refer to Patent Document 1 ). In addition, a TV is proposed that connects a series resonant circuit composed of capacitors / inductors in front of the input tuning circuit for the VHF band, and attenuates the VHF low-band signal when receiving the VHF high-band, thereby obtaining the suppression effect of the VHF low-band. Tuner (for example, refer to Patent Document 2). [0003] Figure 7 It is a circuit configuration diagram of the TV tuner described in Patent Document 1. [0004] A VHF tuner 101 for receiving t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04N5/50H03J5/24H04B1/18H04N5/44H04N5/46
CPCH03J5/244
Inventor 山本正喜
Owner ALPS ALPINE CO LTD
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