JPS5997232A - Level adjuster - Google Patents

Abstract

PURPOSE:To adjust the signal level of each band independently, by providing plural filter circuits, which include variable resistances and are different in pass band from one another, in parallel. CONSTITUTION:A level adjuster 2 consisting of a parallel connection circuit of the first level adjusting part 7 and the second level adjusting part 8 is interposed between an antenna 1 receiving the VHF signal of television and a television receiver 5. The first level adjusting part 7 is provided for adjusting the level of the signal of the VHF low band and is constituted by inserting a variable resistance 15 to the series arm of a band-pass filter circuit consisting of coils 9, 10, and 11 and capacitors 12, 13, and 14. The second level adjusting part 8 is provided for adjusting the level of the signal of the VHF high band and is constituted similarly. Variable resistances 15 and 22 are adjusted to adjust signal levels of low and high bands independently.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a level adjuster used for television reception and the like.

Embodiments of the present application will be described below with reference to the drawings.

FIG. 1 is an explanatory diagram of a television reception system.

1 is an antenna that receives television VHF signals.

2 represents a level adjuster, 3 represents its input end, and 4 represents its output end. The configuration of the level adjuster 2 will be detailed later. Reference numeral 5 indicates a television receiver, and 6 indicates a power supply line connecting each device. The level adjuster 2 includes a first level adjuster 7
and a second level adjustment section 8 connected in parallel. The first level adjustment unit 7 is for adjusting the level of a TV VHF low band signal, for example, and has coils 9, 10, . 11 and capacitor 12.13
．． It is constructed by interposing a variable resistor 15 in the series arm of a bandpass filter circuit consisting of 14 and 14. The second level adjustment unit 8 is for adjusting the level of a TV VHF high band signal, for example, and as shown in the figure, a coil 16.1
7.18 and capacitors 19, 20, and 21, with a variable resistor 22 interposed in the series arm of a bandpass filter circuit.

The operation of the television receiving system having the above configuration will be explained. TV VHF low band signal is better than TV VH
It is assumed that the level of the F high band signal is also high. The TV HF signal received by the antenna 1 is applied to the input terminal 3 of the level adjuster 2.

Among these signals, the Thereze VHF low band signal passes through the first level adjustment section 7 and appears at the output terminal 4 after being attenuated by an appropriate attenuation amount. On the other hand, the TV VHF high band signal passes through the second level adjustment section 8 with less attenuation and appears at the output terminal 4. The television VHF low band signal and the television VHF high band signal are uniformly level-adjusted to a proper level and received by the television receiver 5. The television receiver 5 can receive good images of both VHF low band signals and VHF high band signals without mutual interference.

Next, FIG. 2 is an electrical characteristic diagram of the level adjuster, and shows the layout with fewer people. Characteristic A shows the case where the resistance values of the variable resistors 15 and 22 are both the minimum, characteristic B shows the case where the resistance value of the variable resistor 15 is the maximum, and characteristic C shows the case where the resistance value of the variable resistor 22 is the maximum.

The variable resistors 15 and 22 have a minimum value of 00 and a maximum value of 6, respectively.
A variable resistance in the range of 80Ω was used. Other circuit constants are for coils 9, 10, 11, 16, 17, and 18 with 11 turns, 3 turns, 11 turns, 7 turns, 4 turns, and 7 turns (
Coil] 7 has a wire diameter of 0.5 m and a winding diameter of 3 m, and the other coils have a wire diameter of 0.5 m and a winding diameter of 4 m. 1.8pF, 22pF, 10pF, 5 respectively.
pF, 18pF.

It was constructed using 3 pF. The impedance of the measurement system was 75Ω. As is clear from FIG. 2, the first level adjustment section 7 and the second level adjustment section 8
HI'i'' low band signal and VHF high band signal can be attenuated independently, so vH
It is possible to adjust the output of both F low band and VHF high band signals to be uniform, and it is also possible to bring the output to an appropriate level. It is also clear that the above adjustment can be achieved by simply providing one variable resistor 15, 22 in each of the level adjusting sections 7 and 8.

The above explained the level adjustment of VHF low band signal and VHF high band signal, but VHF signal and U
Level adjustment with the HF signal is also possible. It is also possible to connect three or more level adjustment sections in parallel, such as a third level adjustment section, a fourth level adjustment section, and so on, to individually adjust the level of each band signal.

Next, FIG. 3 is a wiring diagram showing a level adjuster having a different configuration, and those having the same or equivalent functions as those in FIG. 1 are indicated by the same reference numerals with the letter e added thereto, and redundant explanation will be omitted. The first level adjustment section 7e has a configuration in which a variable resistor 15e is inserted into a low-pass filter circuit consisting of coils 23, 24 and a capacitor 25. The element value of each element is preferably selected so that a predetermined passband can be obtained even when the resistance value of the variable resistor 15e is at its maximum. The second level adjustment section 8e has a configuration in which a variable resistor 22e is inserted into a bypass filter circuit consisting of a coil 26 and capacitors 27 and 28. The element value of each element is determined by the first level adjustment section 7.
Similarly to e, the variable resistor 22e is selected so that a predetermined passband can be obtained even when the resistance value is at its maximum.

The level adjustment section 7e adjusts signals from DC to VHF low band, for example, and the level adjustment section 8e adjusts signals from, for example, VHF low band.
It is provided to adjust signals of frequencies above the high band.

The above has described a level adjuster consisting only of passive elements, but each level adjustment section 7, 8 (or 7e, 8e)
Needless to say, level adjustment is also possible by interposing a broadband amplifier between the output mixing point and the output end 4 (or 4e).

As described above, in the present invention, a signal dispersed in a wide band is divided into a plurality of narrow band signals, and the levels can be adjusted independently for each signal, so that each signal can be adjusted to a uniform appropriate level at the output end 4. This has the effect that it can be sent to the subsequent stage. This prevents the respective signals from mutually interfering with each other in the subsequent stage.

Furthermore, since the level adjuster has a simple structure in which only one variable resistor is interposed in the series arm of the filter circuit, it can be provided at low cost.

[Brief explanation of the drawing]

The drawings show embodiments; FIG. 1 is an explanatory diagram of a television reception system, FIG. 2 is an electrical characteristic diagram of a level adjuster, and FIG. 3 is a wiring diagram showing a level adjuster with a different configuration. 2... Level adjuster, 3... Input end, 4... Output end, 7... First level adjustment section, 8... Second level adjustment section, 15.22... Variable resistance. Patent applicant Maspro Electric Works Co., Ltd. Representative Takashi Hatayama Figure 1 Figure 2 PJ fluid count (MH2) -- Figure 3

Claims (1)

[Claims] In a level adjuster comprising a plurality of level adjustment sections connected in parallel between an input end and an output end, each level adjustment section has a filter circuit with a different pass band and a series arm of the filter circuit. A level adjuster characterized by comprising an interposed variable resistor.