Television – Receiver circuitry
Reexamination Certificate
1998-07-01
2001-06-26
Eisenzopf, Reinhard J. (Department: 2614)
Television
Receiver circuitry
C348S731000, C455S180100
Reexamination Certificate
active
06252633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a television signal receiver comprising a radio-frequency tuner and at least two subsequent surface-acoustic wave filters, in which the radio-frequency tuner filters a radio frequency television signal applied to its input and converts it to an intermediate-frequency television signal which is coupled to the surface-acoustic wave filter.
2. Description of the Related Art
Such television signal receivers are particularly implemented with a plurality of surface-acoustic wave filters for receiving radio-frequency television signals of different transmission standards. These surface-acoustic wave filters are activated or deactivated by means of associated switches. There are also concepts in which the filter characteristics of the surface-acoustic wave filters are switched in such a way that different inputs of the surface-acoustic wave filters are switched to a reference potential. The drawback of both concepts is the multitude of required switches and the attendant elaborate number of components.
SUMMARY OF THE INVENTION
It is an object of the invention to reduce the number of components for such a television signal receiver for multistandard reception.
According to the invention, this object is solved in that the radio-frequency tuner has at least two outputs which supply the IF television signal converted to the intermediate frequency, in that each output is associated with a switch by means of which the associated output is switchable to a fixed reference potential, in that the radio-frequency tuner precedes at least two surface-acoustic wave filters, in which each time, a first input of the two surface-acoustic wave filters is coupled to a first output of the radio-frequency tuner, and a second input of the two surface-acoustic wave filters is coupled to a second output of the radio-frequency tuner, and in that, for switching the filter characteristic of the television signal receiver, alternately one of the outputs of the radio-frequency tuner and the inputs coupled thereto of the surface-acoustic wave filters can be coupled to the reference potential by means of the associated switch.
In this concept, according to the invention, the radio-frequency tuner has at least two outputs, both of which supply the RF television signal converted to the intermediate frequency. Each output is associated with a switch by means of which the associated output is switchable to a reference potential.
For example, in a concept with two outputs of the RF tuner, subsequently arranged surface-acoustic wave filters have one of their inputs connected to an output of the RF tuner. The switches associated with the outputs of the RF tuner provide the possibility of a switch-over or switch on/off of the surface-acoustic wave filters, dependent on their construction. In this way, the filter characteristic of the television signal receiver can be switched, for which purpose, only the two switches associated with the outputs are required.
In the case of activated switches, the associated output is low-ohmic and, in addition to the deactivation of this output, it simultaneously allows a switch-over or switch on/off of the subsequent surface-acoustic wave filters.
On the one hand, this leads to a reduction of the number of required switches and, on the other hand, these switches can be constructed together with the RF tuner because they are associated with the outputs of this tuner.
In accordance with an embodiment of the invention, at least one of the surface-acoustic wave filters is implemented in such a way that its filter characteristic changes in dependence upon which of its inputs is coupled to reference potential, and in that the filter characteristic of the surface-acoustic wave filter is switchable by means of the switches associated with the outputs of the radio-frequency tuner.
Surface-acoustic wave filters of this type have two inputs, both of which can receive signals to be filtered. Alternatively, however, one of the inputs must be connected to a reference potential, which leads to a switch of the filter characteristic of the surface-acoustic wave filter. The other input then remains an active input, whose input signal is filtered with the corresponding, activated filter characteristic. In the television signal receiver according to the invention, such filters have one of their inputs connected to one of the outputs which are switchable at a low-ohmic value. Due to the alternative activation of the switches associated with the outputs of the RF tuner, the filter characteristic of such a surface-acoustic wave filter is switched in a simple manner.
A further embodiment of the invention is characterized in that at least one of the surface-acoustic wave filters is implemented in such a way that the filter can be cut off in dependence upon which of its inputs is coupled to reference potential, and in that the surface-acoustic wave filter can be cut off by means of the switches associated with the outputs of the radio-frequency tuner. In this type of switch, the surface-acoustic wave filter can be switched on/off by the switches associated with the outputs of the RF tuner, which filter can thus be cut off or activated by means of the switches.
Surface-acoustic wave filters of both these types may be combined in a circuit arrangement according to the invention. In the television signal receiver according to the invention, this leads to a smaller number of components, even when a complex construction is used, i.e., a multitude of such filters and switchable filter characteristics, because the number of switches required is dependent on the number of outputs of the RF tuner.
This advantage of the television signal receiver according to the invention becomes particularly manifest when switching operations between a multitude of filter characteristics have to be performed. This is the case, for example, in multistandard television receivers in which the surface-acoustic wave filter must be adjustable to each of the receivable television signals of different standards.
To this end, a further embodiment of the invention is characterized in that said television signal receiver is a multistandard television signal receiver for receiving television signals of different transmission standards, and in that the surface-acoustic wave filters and their filter characteristics for adaptation to IF television signals of different transmission standards are switchable by means of the switches.
The simplification of the circuitry obtained in the television signal receiver according to the invention may be further increased in that, in accordance with another embodiment, both outputs and the associated switches of the radio-frequency tuner are implemented on an integrated circuit.
These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter.
REFERENCES:
patent: 5577270 (1996-11-01), Sakai
patent: 5867771 (1999-02-01), Ruitenburg
patent: 6094229 (2000-07-01), Ohshima
patent: 0492914A2 (1991-06-01), None
Eisenzopf Reinhard J.
U.S. Philips Corporation
Yenke Brian P.
LandOfFree
Television signal receiver does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Television signal receiver, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Television signal receiver will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2455535