JPH1188796A - Television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the convenience and to obtain higher sensitivity by switching presence of insertion of an input attenuator that attenuates a television signal from an antenna input terminal in interlocking with a selected channel so as to extend a receptible input electric field strength range. SOLUTION: In the case of setting channel selection, a color television receiver 1 sets an input signal control switch 5 to an an position on when the television signal is within a control range of an automatic gain control cirduit and to an off-position when the operation is set to each channle and stored in a storage circuit 8. In the case of reception, on/off information of the input signal control switch 5 for each channel of the storage circuit 8 is fed to a channel selection circuit 7 to control the input signal attenuator 4 for each channel and a proper signal is sent to a tuner 6. Thus, an excellent reception state is realized even in the mixing state of a strong electric field signal and a weak electric field signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color television receiver.

[0002]

2. Description of the Related Art Conventionally, the input electric field intensity of a color television receiver is adjusted by an AGC circuit (automatic gain control circuit). However, in order to cope with a high electric field strength level exceeding the control range of the AGC circuit, an "input signal attenuator" is provided and inserted between the antenna and the tuner.

[0003]

In the above-described method, the weak electric field signal becomes a weak electric field signal by an "input signal attenuator" inserted to cope with a high electric field strength level exceeding the control range of the AGC circuit. Deteriorate the reception state. Therefore, in order to avoid this, the insertion of the "input signal attenuator" must be manually opened and closed each time, and a troublesome operation is required. As another method, if the operating point of the TUNER RF AGC circuit (automatic gain control circuit) is advanced to cope with a strong input level, the S / S
Degrades the N ratio (signal to noise ratio) and does not achieve it. In order to obtain higher sensitivity, there is a means of increasing the gain of a high-frequency amplifier circuit or the like, but it is impossible to increase the gain beyond the control range of the AGC circuit.

SUMMARY OF THE INVENTION An object of the present invention is to solve the conventional drawbacks and to increase the range of receivable input electric field strength by switching the insertion or non-insertion of an "input signal attenuator" in conjunction with a channel selection. To provide a color television receiver with higher sensitivity and higher sensitivity.

[0005]

SUMMARY OF THE INVENTION The present invention provides an input signal attenuator for attenuating a television signal from an antenna input terminal, an input signal control switch for turning on / off the input signal attenuator, channel selection information, Storage circuit for storing ON / OFF information of input signal attenuator, channel selection information based on information of storage circuit, and ON / OF of input signal attenuator
It consists of a tuning circuit that outputs F information.

Further, the present invention relates to channel selection information and ON / O of an RF AGC operation level switch.
A memory circuit for storing FF information, a channel selection circuit based on the information in the memory circuit, a channel selection circuit for outputting ON / OFF information of an RF AGC operation level switch, and an ON / OFF information for each channel of the channel selection circuit. Base RF AGC
It comprises an RF AGC operation level switch for switching the operation level.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is an input signal attenuator for attenuating a television signal from an antenna input terminal, and turning on / off the input signal attenuator.
Input signal control switch means, and a storage circuit for storing channel selection channel information and ON / OFF information of the input signal attenuator, channel selection information and ON / OFF information of the input signal attenuator based on the information of the storage circuit. A color television receiver provided with means of a channel selection circuit for outputting
By setting and storing the insertion state of the "input signal attenuator" according to the electric field strength in advance, the input electric field strength that can be received can be switched by switching the presence or absence of the "input signal attenuator" in conjunction with the selected channel. By expanding the range, a good reception state can be realized even in a mixed state of a strong electric field signal and a weak electric field signal.

According to a second aspect of the present invention, channel selection information and ON / OF of an RF AGC operation level switch are provided.
Means of a storage circuit for storing F information; means of a channel selection circuit for outputting channel selection information and ON / OFF information of an RF AGC operation level switch based on the information of the storage circuit; A color television receiver provided with an RF AGC operation level switching switch for switching the RF AGC operation level based on ON / OFF information of the RF AGC. By setting and storing the ON / OFF state of the operation level changeover switch, the RF AGC operation level changeover switch is switched in conjunction with the selected channel, thereby expanding the receivable input electric field strength range to increase the strong electric field. A good reception state can be realized even in a mixed state of a signal and a weak electric field signal.

(Embodiment 1) FIG. 1 is a block diagram of a television receiver according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a color television receiver of the present invention, and reference numeral 2 denotes a television input signal control circuit. Reference numeral 3 denotes an antenna input terminal for inputting a television signal, 4 denotes an input signal attenuator for attenuating a television signal input from the antenna input terminal 3, and 5 denotes an input signal attenuator which is preset according to the input electric field strength. 4 is an input signal control switch for switching the attenuation level of the input signal.

FIG. 1 shows a state where the switching is made to the strong input electric field side. Reference numeral 6 denotes a TU for selecting a signal of a target channel from the television signal output from the input signal attenuator 4.
NER, 7 is the frequency of the target channel in TUNER 6,
A tuning circuit that supplies reception band information and also supplies ON / OFF information to the input signal attenuator control switch 5. Reference numeral 8 denotes a frequency of each channel, a reception band, and ON / OFF information of the input signal attenuator control switch. This is a storage circuit for storing.

The operation of the television input signal control circuit configured as described above will be described. At the time of channel selection setting, if within the control range of the AGC circuit (automatic gain control circuit) of the color television receiver itself, the input signal control switch 5 is turned on and the input signal attenuator 4 is set to the minimum attenuation. . AG of color television receiver itself
When a strong electric field input signal is out of the control range of the C circuit, the input signal control switch 5 is switched to the OFF side, the input signal attenuator 4 is set to the maximum attenuation, and the A of the color television receiver itself is set.
An electric field input signal within the control range of the GC circuit.

This operation is set for each channel and stored in the storage circuit 8. At the time of reception, the frequency and band information for each channel and the ON / OFF information of the input signal control switch stored in the storage circuit 8 are sent to the tuning circuit 7, and the tuning circuit 7 inputs the frequency and band information to the TUNER 6. The ON / OFF information for each channel is sent to the signal control switch 5 to control the input signal attenuator 4 for each channel.
It is sent to UNER6 as an appropriate signal.

(Embodiment 2) FIG. 2 is a block diagram of a television receiver according to Embodiment 2 of the present invention.

In FIG. 2, reference numeral 21 denotes a color television receiver of the present invention, and reference numeral 22 denotes a television RF.
This is an AGC operation level switching circuit. 23 is an antenna input terminal for inputting a television signal, 24 is a TUNER for selecting a signal of a target channel from a television signal from the antenna terminal input, and 25 is a VIF circuit (video intermediate frequency amplifier circuit) for amplifying an output signal of TUNER4. , 26
Is an RF AGC circuit (automatic gain control circuit) for controlling the gain of the TUNER 4 according to the input signal electric field strength level of the antenna input terminal, 27 is connected between the + power supply and the ground, and the variable terminal 27 c is connected to the RF AGC circuit 26 RF AGC volume to determine the RF AGC operating point.

Reference numeral 28 denotes a channel selection circuit which supplies the frequency and reception band information of the target channel to the tuner 24 and supplies ON / OFF information to the RF AGC operation level changeover switch 10. Reference numeral 29 denotes the frequency and reception band of each channel. ,
RF. This is a storage circuit for storing ON / OFF information of the AGC operation level switch. Reference numeral 10 denotes an RF AGC operation level switch for switching the operation level of the RF AGC circuit 26 under the control of the channel selection circuit 28;
Is the terminal 1 of the RF AGC operation level switch 10
This resistor is connected between Oa and the terminal 27c of the RF AGC volume 7, and controls the amount of switching of the set value of the RF AGC volume 27 by the operation of the RF AGC operation level changeover switch.

The television RF.
The operation of the AGC operation level switching circuit will be described.

If the AGC circuit (automatic gain control circuit) of the color television receiver itself is within the control range, RF A
The GC operation level switch 10 is set to the OFF side, which is the same as the operation of the conventional color television receiver.

At the time of channel selection setting, when a strong electric field input signal is out of the control range of the AGC circuit of the color television receiver itself, RF
Turn the AGC operation level changeover switch 10 to the ON side (10
a and 10b are closed) and the RF AGC circuit 26
, The gain of the tuner 24 is lowered by accelerating the operation start level.

This operation is set for each channel and stored in the storage circuit 29. At the time of reception, the frequency and band information for each channel stored in the storage circuit 29, RF AGC
The ON / OFF information of the operation level changeover switch 10 is sent to the tuning circuit 28. The tuning circuit 28 sends the frequency and band information to the tuner 24 and the RF AGC operation level changeover switch 10 sends the ON / OFF information for each channel. Send
The RFAGC circuit 26 is controlled for each channel.

[0020]

As described above, according to the present invention,
By setting and storing the insertion state of the "input signal attenuator" according to the electric field strength in advance, switching between the insertion and non-insertion of the "input signal attenuator" in conjunction with the selected channel, the strong electric field signal and the weak electric field A good reception state can be realized even in a mixed state of signals, and there is an effect of expanding a receivable input electric field strength range.

In addition, the RF is adjusted according to the electric field strength in advance.
By setting and storing the ON / OFF state of the AGC operation level changeover switch, the RF AGC operation level changeover switch is switched in conjunction with the selected channel to expand the receivable input electric field strength range, thereby increasing the strong electric field. Even in a mixed state of a signal and a weak electric field signal, a good reception state can be realized without deteriorating the S / N ratio in a medium electric field.

[Brief description of the drawings]

FIG. 1 is a block diagram of a television receiver according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a television receiver according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 21 Color television receiver 2 Television input signal control circuit 3 Antenna input terminal 4 Input signal attenuator 5 Input signal control switch 6 TUNER 7 Tuning circuit 8 Storage circuit 21 Color television receiver 22 Television RF AGC operation Level switching circuit 23 Antenna input terminal 24 Tuner 25 VIF circuit (Video intermediate frequency amplification circuit) 26 RF AGC circuit (Automatic gain control circuit) 27 RF AGC volume 27a, 27b, 27c, 10a, 10b Terminal 28 Tuning circuit 29 Storage circuit 10 RF AGC operation level changeover switch 11 Resistor

Claims (4)

[Claims] 1. An input signal attenuator is turned on / off in conjunction with a channel selected by a television receiver to extend an allowable range of an input electric field intensity level, thereby enabling both a strong electric field input and a weak electric field input. A television receiver which realizes a stable reception state. 2. An input signal attenuator for attenuating a television signal from an antenna input terminal, an input signal control switch for turning on / off the input signal attenuator,
Tuning channel information and ON / OF of input signal attenuator
A television receiver comprising: a storage circuit for storing F information; and a channel selection circuit for outputting channel selection information and ON / OFF information of an input signal attenuator based on the information in the storage circuit. 3. The operating point of an RF AGC circuit (automatic gain control circuit) is switched in conjunction with a channel selected by a television receiver to expand the allowable range of the input electric field intensity level, With both weak electric field inputs,
A television receiver that realizes a stable reception state. 4. Channel selection information and RF AGC
Means of a storage circuit for storing ON / OFF information of the operation level changeover switch, channel selection information based on the information of the storage circuit, and O of the RF AGC operation level changeover switch
Means of a tuning circuit for outputting N / OFF information, and RF AG based on ON / OFF information for each channel of the tuning circuit
A television receiver comprising: an RF AGC operation level changeover switch for changing the C operation level.