Television – Receiver circuitry
Reexamination Certificate
1997-10-18
2001-08-28
Eisenzopf, Reinhard J. (Department: 2614)
Television
Receiver circuitry
C348S725000, C348S735000, C348S737000, C348S607000, C455S266000, C455S260000, C455S307000, C455S264000
Reexamination Certificate
active
06281946
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a television receiving apparatus suitable for use, for example, in a portable device. More particularly, the present invention relates to a television receiving apparatus which eliminates the possibility of interference in a received image possibly caused by beat components generated between a harmonic signal of an intermediate frequency signal used therein and a local oscillating signal of a tuner.
BACKGROUND ART
In a portable television receiving apparatus, for example, a television signal is received using an antenna directly coupled to the receiving apparatus, such as a rod antenna or the like. In this event, a harmonic signal of an intermediate frequency signal used within the television receiving apparatus, for example, may be introduced into a tuner through the antenna to possibly cause interference in a received image due to beat components generated between the harmonic signal of the intermediate frequency signal and a local oscillating signal of the tuner.
Conventionally, for such interference, the tuner is provided with a shield case to prevent unnecessary signals from introducing into the tuner from a structural approach. However, such a structural solution may not completely prevent the occurrence of the interference, and additionally incurs a problem of an increase in cost and number of manufacturing steps due to parts including such a shield case etc., an increase in volume and weight of a product, etc.
The present application has been made in view of the problems mentioned above, and has an object to provide a television receiving apparatus which is capable of reliably preventing the occurrence of interference by a simple configuration.
DISCLOSURE OF THE INVENTION
The present invention is intended to make the frequency of beat components between a local oscillating signal of a tuner and a harmonic signal of an intermediate frequency signal coincident with a trap frequency of a filter means by providing a variable frequency oscillating means for changing the frequency of the intermediate frequency signal, and discloses a television receiving apparatus associated therewith.
REFERENCES:
patent: 3454710 (1969-07-01), Gassmann
patent: 4876739 (1989-10-01), Ma et al.
patent: 4979230 (1990-12-01), Marz
patent: 4989264 (1991-01-01), Ohto
patent: 5159711 (1992-10-01), Ma et al.
patent: 5263197 (1993-11-01), Manjo et al.
patent: 5371902 (1994-12-01), Marz
patent: 5644368 (1997-07-01), Natsume
patent: 5724105 (1998-03-01), Hatano
patent: 5864373 (1999-01-01), Hatano
Hisada Osamu
Kuboji Genichiro
Eisenzopf Reinhard J.
Maioli Jay H.
Natnael Paulos
Sony Corporation
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