JPS6122382Y2 - - Google Patents

Description

[Detailed description of the invention] The invention is a multi-functional television receiver, e.g.
Television receiver with FM radio, or SECAM-E and SECAM-L as in France
In antenna input circuits that feed signals from programs in different frequency bands from one antenna terminal board input to multiple internal channel selection devices, such as in television receivers that can simultaneously receive signals from multiple channels, input loss should be minimized as much as possible. The purpose is to reduce the size and supply power to each channel selection device.

Conventionally, in the antenna input circuit of this type of multifunctional television receiver, an antenna input terminal is provided for each channel selection device. For example, in the case of a television receiver with an FM radio, two input terminals are provided: an FM radio antenna input terminal and a television receiver antenna input terminal.

However, recently, the power feed lines from the antenna are combined into one line, so when feeding the antenna input to a multi-function television receiver, it is necessary to use a distributor or duplexer to feed the power to the television receiver. For this reason, when distributed inside a television receiver, an insertion loss of 4 to 7 dB occurs, which is a major factor in the poor image quality of television receivers in areas with weak electric fields or the deterioration of the sound quality of FM radio. The current situation is that

FIG. 1 shows, as a conventional example, an antenna input circuit for a television receiver that can be used in both the SECAM-E system and the SECAM-L system. As shown in Figure 1, the SECAM-E method is a signal only in the VHF band, and the SECAM-L method is a signal only in the VHF band.
It is a signal that has VHF band and UHF band, so it is connected to the input terminal 3a of SECAM-L's tuning device 3.
2 with the input terminal 4a of the SECAM-E channel selection device 4
For VHF band signals, it is necessary to feed antenna input signals to both channel selection devices 3 and 4, so the signal from external antenna 1 is divided into two by divider 2 and fed. ing.

When the antenna signal is distributed by the distributor 2 in this way, as mentioned above, in the VHF band, it is 4 to 5 dB,
In the UHF band, an input loss of 5 to 7 dB occurs.

This invention eliminates these conventional drawbacks, makes the antenna input terminal uniaxial, and reduces insertion loss and
This is to reduce the VSWR and efficiently supply power to each channel selection device to improve image and sound quality.An embodiment of the present invention will be described below with reference to FIGS. 2 to 5, which show an embodiment of the present invention.

FIG. 2 shows SECAM-E according to an embodiment of the present invention.
Can be used with both the SECAM-L method and the SECAM-L method.
This figure shows the antenna input circuit of a multi-functional television receiver. In the figure, 5 is a high-pass filter for the UHF band, 6 and 7 are low-pass filters for the VHF band, and 8 is a SECAM-E system tuning device for VHF band signals. 4 or SECAM-L system selection device 3, for example.
When an antenna input signal is supplied to the SECAM-L channel selection device 3, contacts a and b of the changeover switch 8 are short-circuited. That is, the UHF band signal is supplied to the channel selection device 3 only through the high-pass filter 5, and the VHF band signal is supplied to the channel selection device 3 via the low-pass filters 6 and 7. Also, SECAM-
When supplying the antenna input signal to the E-scheme tuning device 4, it is sufficient to short-circuit contacts a and c of the changeover switch 8, and the VHF band signal is sent to the tuning device 4 only through the low-pass filter 6. Supplied.

In the circuit shown in FIG. 2, the part surrounded by the dotted line is arranged on the antenna terminal board of the television receiver, and the antenna input signal from the external antenna 1 is supplied only to the input terminal 9 through one line. .

As is clear from the above configuration, the antenna input circuit of the present invention uses the SECAM-E method.
In the case of a television receiver having two SECAM-L system channel selection devices 3 and 4, only the VHF band is switched by the changeover switch 8 to supply antenna input signals to the channel selection devices 3 and 4. , the loss in the distributor 2 and the connector is eliminated,
As shown in FIGS. 3 to 5, the input loss can be kept within 2 dB in the VHF band and within 3 dB in the UHF band.

As described above, according to the present invention, a television receiver with low input loss and excellent image and sound quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an antenna input circuit of a conventional multi-function television receiver, FIG. 2 is a block diagram of an antenna input circuit of a multi-function television receiver according to an embodiment of the present invention, and FIGS. FIG. 5 is a diagram showing the input loss depending on the frequency band in the antenna input circuit of the present invention. 1... External antenna, 3, 4... Tuning device, 5
...High pass filter, 6,7...Low pass filter, 8...Selector switch, 9...Input terminal.

Claims (1)

[Scope of utility model registration request] a first channel selection device that receives a signal in a first frequency band and a signal in a second frequency band; and a second channel selection device that receives only a signal in the first frequency band; Antenna input signal 1 from antenna
In the antenna input circuit of a multi-functional television receiver that supplies the antenna to the first and second channel selection devices via two input terminals, the second frequency is connected between the input terminal and the first channel selection device. A filter circuit for passing a signal in a first frequency band is connected between the input terminal and a common contact of the switch, and a filter circuit for passing a signal in a first frequency band is connected between the first individual contact of the switch and the common contact of the switch. A multi-function device in which a filter circuit for passing signals in the first frequency band is connected between the first channel selection device and a second individual contact of the switch is connected to the second channel selection device. Antenna input circuit for television receivers.