CN2532636Y

CN2532636Y - Electronic tuner with built in frequency band control circuit

Info

Publication number: CN2532636Y
Application number: CN01271613U
Authority: CN
Inventors: 孙燕
Original assignee: Chengdu Xuguang Technology Co ltd
Current assignee: Chengdu Xuguang Technology Co ltd
Priority date: 2001-11-05
Filing date: 2001-11-05
Publication date: 2003-01-22
Anticipated expiration: 2011-11-05

Abstract

The utility model discloses an electronic tuner with internal band control circuit and comprises a high-pass filtering loop 1, a medium frequency wave trap loop 2, an input loop 3, a high level radioactive loop 4, an interstage double tuning loop 6, a frequency mixer 7, an oscillating loop 8, a medium frequency selecting loop 9, and a medium frequency amplifying loop 10. The input loop 3, the high level radioactive loop 4, the interstage double tuning loop 6, the frequency mixer 7, and the oscillating loop 8 respectively control three high level radioactive loops corresponding to three bands through three extracting terminals BS. The utility model takes up relatively little integrated circuit pin resources and reduces the manufacturing cost and labor cost of televisions. An electronic switch converting circuit 5 used for reducing the use of external pins is arranged between the high level radioactive loop 4 and the external pin BS. The utility model occupies little integrated circuit pin resources and reduces the manufacturing cost of televisions.

Description

The electronic tuning unit of built-in frequency range control circuit

The utility model belongs to sound, video reception apparatus is made the field.

At present, band IC interior bus (I ²C) each big TV factory produces Kong Zhi digital to television machine in a large number in the whole nation, cooperates the tuner of this television set also to adopt in a large number.This tuner is generally upward put back to road, inter-stage frequency selection by dual-tune loop, frequency mixer, oscillation circuit, frequency-selecting of intermediate frequency loop, intermediate frequency amplifying return circuit etc. by high-pass filtering loop, intermediate frequency trap-wave loop, input circuit, height and is constituted, wherein the high-pass filtering loop links to each other with the aerial signal input, and the intermediate frequency amplifying return circuit links to each other with medium frequency output end.Input circuit, height are put back to road, inter-stage frequency selection by dual-tune loop, frequency mixer, oscillation circuit because of frequency covers too wide be divided into three sections (VHF Low, VHF High, UHF), tuner VHF Low that has and the shared height of VHF High are put back to road, frequency mixer), the height of controlling three frequency range correspondences by three leading-out terminals is put back to road, oscillation circuit work respectively.This tuner has and uses simple, performance index advantage preferably, but concerning the whole set of television developer, control tuner three pins that will account for, the integrated circuit pin comparison anxiety that will seem for the television set with many functions.For addressing this problem, many television sets have increased an integrated circuit that is exclusively used in the frequency range conversion on complete machine, and this has not only increased the cost of television set, and make originally circuit of the more complicated complexity more that becomes of television set.

The purpose of this utility model is a kind of novel electronic tuner of design, makes it to overcome the above shortcoming of prior art, less takies the integrated circuit pin resource, and reduces the television set manufacturing cost.

The purpose of this utility model is to realize by following means.

The electronic tuning unit of built-in frequency range control circuit comprises that high-pass filtering loop, intermediate frequency trap-wave loop, input circuit, height put back to road, inter-stage frequency selection by dual-tune loop, frequency mixer, oscillation circuit, frequency-selecting of intermediate frequency loop, intermediate frequency amplifying return circuit; Input circuit, height are put back to road, inter-stage frequency selection by dual-tune loop, frequency mixer, oscillation circuit and are covered too wide being divided into because of frequency: three sections of VHF Low, VHF High, UHF, the height of controlling three frequency range correspondences by three leading-out terminal BS is put back to road 4, oscillation circuit 8 work respectively, puts back at height and is provided for reducing the electronic switch change-over circuit 5 that uses external number of pins between road 4 and external pin BS.

After having adopted design as above, originally three frequency ranges of three pin control of introducing can be become by two or three frequency ranges of a pin control, so not only saved pin, but also the pin of saving can have been transformed into other purposes (for example in superpower reception electronic tuning unit, be used for control antenna amplifier LNA).Adopt structure of the present utility model, comparing to has increased a method that is exclusively used in the integrated circuit of frequency range conversion on the television set complete machine, and cost is lower, and circuit is also more simple, stable.

Description of drawings is as follows:

Fig. 1 is the circuit block diagram of this product.

Fig. 2, Fig. 3, Fig. 4 are the dissimilar electronic switch change-over circuit part schematic diagram of the utility model.

Fig. 5, Fig. 6, Fig. 7 are the dissimilar electronic switch change-over circuit logic relation picture of utility model.

Below in conjunction with accompanying drawing structure of the present utility model is described in further detail.

Fig. 1 has provided total circuit block diagram of this product, and it is identical with the circuit of at present general international standard type electronic tuning unit that the high-pass filtering loop 1 among the figure, intermediate frequency trap-wave loop 2, input circuit 3, height are put back to road 4, inter-stage frequency selection by dual-tune loop 6, frequency mixer 7, oscillation circuit 8, frequency-selecting of intermediate frequency loop 9, intermediate frequency amplifying return circuit 10.Input circuit 3, height are put back to road 4, inter-stage frequency selection by dual-tune loop 6, frequency mixer 7, oscillation circuit 8 and are divided into three sections (VHF Low, VHF High, UHF because of the frequency covering is too wide, tuner VHF Low that has and the shared height of VHF High are put back to road, frequency mixer), the height of controlling three frequency range correspondences by three leading-out terminals is put back to road 4, oscillation circuit 8 work respectively.For solve television set integrated circuit pin anxiety, reduce television set cost, simplify TV set circuit, this product electronic tuning unit inner built-in stable performance, electronic switch change-over circuit 5 with low cost.

Above-mentioned electronic switch change-over circuit such as Fig. 2, Fig. 3, shown in Figure 4 now are illustrated respectively its operation principle.

Circuit working principle shown in Figure 2: when the BS1 terminal be high level 1, when the BS2 terminal is low level 0, dual switch D1 one road saturation conduction VL is the work of high level control VHF Low section, another road is by making that VH is that low level control VHF High does not work; Equally, when the BS1 terminal be low level 0, when the BS2 terminal is high level 1, biswitch triode D1 one road saturation conduction VH is the work of high level control VHF High section, another road is that low level makes VHF Low not work by VL.And be low level when BS1, BS2 terminal have arbitrary terminal, the control voltage of then controlling VHF Low and VHF High work always has one to be high level, so just make a conducting is also always arranged among the biswitch diode D2, one is ended, the negative pole of switching diode D3 is a high level just, therefore, switching diode D3 is a high level by making the base stage of switch triode D4, and D4 is that low level control UHF section is not worked for cut-off state UHF.And as BS1, when BS2 is high level, VL, VH are low level, and biswitch diode D2 also is in cut-off state, and the negative pole of D2, D3 is a low level, and switch triode D4 saturation conduction, UHF are the work of high level control UHF section.Therefore, in listed three kinds of logics, three frequency ranges all have only a frequency range job at arbitrary state in table.The logical relation of its work is seen shown in Figure 5.

Circuit working principle shown in Figure 3, when the BS1 terminal be high level 1, when the BS2 terminal is low level 0, control VL be the work of high level VHF Low section, VH is that low level VHF High does not work; Equally, when the BS1 terminal be low level 0, when the BS2 terminal is high level 1, control VH be the work of high level VHFHigh section, VL is that low level makes VHF Low not work.And be high level when BS1, BS2 terminal have arbitrary terminal, the control voltage of then controlling VHF Low and VHF High work always has one to be high level, internal resistance dividing potential drop by resistance R 49, R50, R51, R52 and switch triode D1, make that the base voltage of switch triode D1 is enough high, control D1 ends, and UHF is that low level control HF section is not worked; And as BS1, when BS2 is low level, VL, VH are low level, by the internal resistance dividing potential drop of resistance R 49, R50, R51, R52 and switch triode D1, make that the base voltage of switch triode D1 is enough low, control D1 saturation conduction, UHF are the work of high level control UHF section.Therefore, in listed three kinds of logics, three frequency ranges also all have only a frequency range job at arbitrary state in table.The logical relation of its work as shown in Figure 6.

Circuit working principle shown in Figure 4, switch triode D1, D2 saturation conduction when the BS terminal is low level 0 (0V), VL is that high level control D3 ends, VH is a low level, the work of VHF Low section, and VHF High does not work, VL, VH are by the internal resistance dividing potential drop of resistance R 2, R3, R4, R5 and switch triode D4, make that the base voltage of switch triode D4 is enough high, control D4 ends, and UHF is that low level control UHF section is not worked; When the BS terminal voltage between low level 0 (0V) and high level 1 (5.0V) (2.0～3.0V) time, switch triode D1 ends, the D2 saturation conduction, VL is a low level control D3 saturation conduction, VH is a high level, the work of VHF High section, and VHF Low does not work, VL, VH are by the internal resistance dividing potential drop of resistance R 2, R3, R4, R5 and switch triode D4, make that the base voltage of switch triode D4 is enough high, control D4 ends, and UHF is that low level control UHF section is not worked; When the BS terminal is high level 1 (5.0V), switch triode D1, D2, D3 end, VL, VH are low level, VHF Low, VHF High do not work, VL, VH are by the internal resistance dividing potential drop of resistance R 2, R3, R4, R5 and switch triode D4, make that the base voltage of switch triode D4 is enough low, control D4 saturation conduction, UHF are the work of high level control UHF section; Therefore, in listed three kinds of states, three frequency ranges also all have only a frequency range job at arbitrary state in table.The logical relation of its work as shown in Figure 7.In this example, only realized the switching of three frequency ranges with a pin.

Though this product is described, this product can be made amendment by many modes, and all such modifications are easy to do for the professional and technical personnel, so some modifications can not be regarded as a departure from spirit and scope described herein like this.

Claims

1, the electronic tuning unit of built-in frequency range control circuit, comprise that high-pass filtering loop 1, intermediate frequency trap-wave loop 2, input circuit 3, height put back to road 4, inter-stage frequency selection by dual-tune loop 6, frequency mixer 7, oscillation circuit 8, frequency-selecting of intermediate frequency loop 9, intermediate frequency amplifying return circuit 10; Input circuit 3, height are put back to the height of road 4, inter-stage frequency selection by dual-tune loop 6, frequency mixer 7, oscillation circuit 8 controlling three frequency range correspondences by three leading-out terminal BS respectively and are put back to road work, it is characterized in that, put back at height and be provided for reducing the electronic switch change-over circuit 5 that uses external number of pins between road 4 and external pin BS.