MXPA99000508A - Tuning circuit do - Google Patents

Abstract

The present invention relates to one end of a high-band tuning winding in a primary tuning circuit and one end of a high-band tuning winding in a secondary tuning circuit, first switching diode and a second diode are provided. series switching devices, a second coupling winding is provided between the ground connection and the connection point of the first switching diode of the second switching diode, both the first switching diode and the second switching diode are set to a switching state. of continuity or a non-continuity state to switch between a high band state and a band status

Description

DOUBLE TUNING CIRCUIT BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The present invention relates to a dual tuning circuit used as a tuning circuit between stages of the tuner of a television set, and more specifically, to a dual tuning circuit in which a high band coupling winding is provided independently. and a low-band coupling winding for coupling a primary tuning circuit to a secondary tuning circuit. 2. DESCRIPTION OF THE RELATED TECHNIQUE Figure 5 shows a conventional double tuning circuit. In Figure 5, a dual tuning circuit 51 is connected to a high frequency amplifier (not shown) at an input end 51a to a mixer (not shown) at the output end 51b. The double tuning circuit 51 is connected switched between a high band and a low band between a so-called band switching method. A primary tuning circuit 51c is provided with a high band tuning winding 52 and a low band tuning winding 53 connected in series at each end of each winding. Between the connection point thereof and the ground connection, a switching diode 54 and a direct current blocking capacitor 55, connected in series, are connected. The cathode of the switching diode 54 is connected to the connection point of the high-band tuning winding 52 and the low-band tuning winding 53, and the other end of the high-band tuning winding 52 is connected to the input end 51a . Between the input end 51a and the ground connection, a direct current blocking capacitor 56 and a varactor diode 57, connected in series, are connected, and the varactor diode 57 anode is connected to ground. A secondary tuning circuit 51d is provided with a high-band tuning winding 58 and a low-band tuning winding 59, connected in series at one end of each winding. Between the connection point thereof and the ground connection, a switching diode 60 and a direct current blocking capacitor 61, connected in series, are connected. The cathode of the switching iodine 60 is connected to the connection point of a high-band tuning winding 58 and the low-band tuning winding 59, and the other end of the high-band tuning winding 58 is connected to the output end 51b. Between the output end 51b and the ground connection, a direct current blocking capacitor 62 and a varactor diode 63 connected in series are connected, and the anode of the varactor diode 63 is connected to ground. The other end of the low-band tuning winding 53 in the primary tuning circuit 51c is connected to the other end of the low-band tuning circuit 59 in the secondary tuning circuit 51d. Between the connection point thereof and the ground connection, a coupling winding 64 and a direct current blocking capacitor 65 connected in series are provided. The direct current blocking capacitor 65 is connected to ground. The connection point of the coupling winding 64 in the direct current blocking capacitor 65 is connected to one end of a power receiver 66, and the other end thereof is connected to a low band switching terminal 67. The point switching anode of the switching diode 54 and direct current blocking capacitor 55 in primary tuning circuit 51c is connected to one end of a supply resistor 68, and the other end thereof is connected to a switching terminal of high band 69. In the same way, the connection point of the anode of the switching diode 60 and the direct current blocking capacitor 61 in the secondary tuning circuit 51d is connected to one end of the supply resistor 70., and the other end thereof is connected to a high band switching terminal 69. The connection point of the direct current blocking capacitor 56 and the varactor diode 57 in the primary tuning circuit 51c is connected to one end of a power resistor 71, and the other end thereof is connected to a tuning voltage terminal 72. In the same manner, the connection point of the direct current blocking capacitor 62 and the varactor 63 in the secondary tuning circuit 51d is connected to one end of the power resistor 73, and the other end thereof is connected to the tuning voltage terminal 72. In the above configuration, a tuning voltage is applied to the tuning voltage terminal 72. The voltage is changed alternating the capacitance of the varactor diode 57 in the primary tuning circuit 51c and the capacitance of the varactor diode 63 in tuning circuit secondary 51d, which has to change the tuning frequency of the double tuning circuit 51. The switching of bands in which the double tuning circuit 51 is switched between a state in which a transmission signal is received is then described. of high band and a state in which a low band television signal is received.

By switching the double tuning circuit 51 shown in FIG. 5 to a state in which a low band television signal is received, a voltage of 5 V is applied, for example, to the low band switching terminal 67. it applies a voltage to the switching diode 54 and the switching diode 60 in reverse directions and both switching diodes 54 and 60 become a non-continuity state. Therefore, the double tuning circuit 51 shown in Fig. 5 functions as an equivalent circuit shown in Fig. 6. In the equivalent circuit shown in Fig. 6, a winding 74 in the primary tuning circuit 51c indicates the winding of high band tuning 52 and the low band tuning winding 53 connected in series, and a winding 75 in the secondary tuning circuit 51d indicates the high band tuning winding 58 and the low band tuning winding 59 connected in series . The coupling winding 64 connected between the ground connection and the connection point of the winding 74 in the primary tuning circuit 51c and the winding 75 in the secondary tuning circuit 51d determines the coupling state between the primary tuning circuit 51c and the secondary tuning circuit 51d to a low band. In the scope thereof it is specified in advance such that the dual tuning circuit 51 has a predetermined transfer characteristic. Therefore, the tuning circuit 74 in the primary tuning circuit 51c and the tuning winding 75 in the secondary tuning circuit 51d does not cause direct inductive coupling. On the other hand, to switch the double tuning circuit 51 shown in FIG. 5 to a state in which a high band television signal is received, a band switching voltage of 5 V is applied, for example, to a high band switching terminal 69. A voltage is applied to the switching diode 54 and the switching diode 60 in forward directions and both switching diodes 54 and 60 are converted to a continuity state. As a result, the connection point of the high-band tuning winding 52 and the low-band tuning winding 53 in the primary tuning circuit 51c, and the connection point of the high-band tuning winding 58 and the tuning winding low band 59 in the secondary tuning circuit 51d are connected to ground at high frequencies. Since the low-band tuning winding in the primary tuning circuit 51c, the low-band tuning winding 59 in the secondary tuning circuit 51d, or the coupling winding 64 does not work, the dual-tuning circuit 51 shown in FIG. Fig. 5 functions as an equivalent circuit shown in Fig. 7. Therefore, a high-band tuning winding 52 in the primary tuning circuit 51 c and the high-band tuning winding 58 in the secondary tuning circuit 51b are exposed to a predetermined distance so that they are coupled so as to obtain a coupling state between the primary tuning circuit 51c and the secondary tuning circuit 51d. In the conventional double tuning circuit 51, however, the positional ratio (physical distribution) between the high-band tuning winding 52 in the primary tuning circuit 51c and the high-band tuning winding 58 and the tuning circuit Secondary 51d needs to be specified in advance to obtain an appropriate coupling state between the primary tuning circuit 51c and the secondary tuning circuit 51d in a state in which a high-band television signal is received. Therefore, the degree of freedom in the design of the physical distribution is limited.

BRIEF DESCRIPTION OF THE INVENTION According to the above, it is an object of the present invention to increase the degree of freedom in the physical distribution design of the high band tuning winding, independently providing coupling windings for a state in which a low band television signal is received. and for a state in which a high band television signal is received. The above object according to the present invention is achieved by the provision of a dual tuning circuit which includes: a primary tuning circuit having a high band tuning winding and a low band tuning winding connected in series in a end of each winding; a secondary tuning circuit having a high-band tuning winding and a low-band tuning winding connected in series at each end of each winding; a first coupling winding disposed between the ground connection and the connection point in which the other end is connected in the low-band tuning winding in the primary tuning circuit to the other end of the low-band tuning winding in the secondary tuning circuit; a first switching diode and a second switching diode connected in series connected between the single end of the high-band tuning winding in the primary tuning circuit and the single end of the high-band tuning winding in the secondary tuning circuit; and a second coupling winding disposed between the ground connection and the connection point of the first switching diode and the second switching diode, in which, when a high band television signal is received, the first switching diode and the second switching diode is set to a continuity state; and when a low band television signal is received, the first switching diode the second switching diode is set to a non-continuity state. Since coupling windings are provided for both high band and low band, a limitation on the physical distribution of not only the low band tuning winding, but also the high band tuning winding is eliminated, and the degree of freedom in design. The dual tuning circuit can be configured in such a way that it also includes a first switching terminal and a second switching terminal; the first switching diode and the second switching diode are connected in series by their anodes or by their cathodes; the anodes are connected to the first terminal of the switched coupling of the coupling with direct current; the cathodes are connected to a second switching terminal as a direct current coupling; and the first switching diode and the second switching diode are set to a continuity state or a non-continuity state by a band switching voltage applied to the first switching terminal and the second switching terminal. In this case, switching between the high band and the low band is facilitated. The double tuning circuit can also be configured in such a way that the first coupling winding is connected to earth via a first direct current blocking capacitor; the second coupling winding is connected to earth via a second direct current blocking capacitor; the connection point of the first coupling winding and the first direct current blocking capacitor is connected to the first switching terminal as a direct current coupling; and the connection point of the second coupling winding and the second direct current block capacitor is connected to a second switching terminal as a direct current coupling. In this case, the first switching diode and the second computing diode are easily connected to the first switching terminal and the second switching terminal.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a double tuning circuit circuit diagram according to one embodiment of the present invention. Figure 2 is an equivalent circuit of a double tuning circuit according to the present invention in a low band state. Figure 3 is an equivalent circuit of a double tuning circuit according to the present invention in a high band state. Figure 4 is a circuit diagram of a double tuning circuit according to another embodiment of the present invention. Figure 5 is a circuit diagram of a conventional double tuning circuit. Figure 6 is an equivalent circuit of a conventional double tuning circuit in a low sided state. Figure 7 is an equivalent circuit of a conventional double tuning circuit in a high band state.

DESCRIPTION OF THE PREFERRED MODALITIES In Figure 1 it shows a double tuning circuit according to the present invention. In Figure 1, a dual tuning circuit 11 is connected to a high frequency amplifier (not shown) at an input end Ia and a mixer (not shown) at an output end 11b. The double tuning circuit 11 is switched between a high band and a low band by a so-called band switching method. A primary tuning circuit 11c is provided with a high-band tuning winding 12 and a low-band tuning winding 13 connected in series at one end of each winding. At another end of the high band tuning winding 12 is connected to the input end lia. A direct current blocking capacitor 14 and a varactor diode 15 connected in series and the anode of the varactor diode 15 is connected to ground are connected between the input end Ia and the ground connection. A secondary tuning circuit-lid is provided with a high-band tuning winding 16 and a low-band tuning winding 17 connected in series at one end of each winding. The other end of the high band tuning winding 16 is connected to the output end lid. A direct current blocking capacitor 18 and a varactor diode 19 connected in series and the anode of the varactor diode 19 which is connected to ground are connected between the output end lid and the ground connection. At another end of the low-band tuning winding 13 in the primary tuning circuit 11c is connected to another end of the low-band tuning circuit 17 in the secondary tuning circuit lid. Between the connection point thereof and the ground connection, a first coupling winding 20 and first direct current blocking capacitor connected in series are connected. The first direct current blocking capacitor 21 is connected to ground. Between the connection point of the high-band tuning winding 12 and the low-band tuning winding 13 and the primary tuning circuit 11 c, and the connection point of the high-band tuning winding 16 and the band-tuning winding When the secondary tuning circuit 11 d is turned off, a first switching diode 22 and a second switching diode 23 connected in series are provided. The connection point of the high-band tuning winding 12 and the high-band tuning winding 13 in the primary tuning circuit 11 c is connected to the anode of the first switching diode 22, and the connection point of the tuning winding of high band 16 and the low band tuning winding 17 in the secondary tuning circuit 11 d is connected to the second switching diode 23. Between the ground connection and the connection point of the first switching diode 22 and the second diode of commutation 23, are provided in a second coupling wire feeder 24 and a direct current blocking capacitor 25 connected in series. The second direct current blocking capacitor 25 is connected to ground. The connection point of the second coupling wire feeder 24 and the second direct current blocking capacitor 25 is connected to a direct 25 feed is connected 26 and the other end thereof is connected to a first switching terminal 27. The connection point of the high-band tuning winding 12 and the low-band winding 13 in the primary tuning circuit 11 c one end of a feed resistor 28 is connected and another end thereof is connected to a second terminal 29. In the same way, the connection point of the high-band tuning winding 16 and the low-band tuning winding 17 in the second tuning circuit 11 d which is connected to one end of the supply resistor 30 and another end thereof is connected to the second switching terminal 29. The connection point of the direct current blocking capacitor 14 and the varactor diode 15 in the primary tuning circuit 11 c is connected to one end of a supply resistor 31 and another end thereof is connected to a tuning voltage terminal 32. In the same way, the connection point of the direct current blocking capacitor 18 and the varactor diode 19 in the second tuning circuit 11 d is connected to one end of a supply resistor 23 and another end thereof is connected to the tuning voltage terminal 32. The band switching in which the circuit of Double tuning 11 is switched between a state in which a high band television signal is received and a state in which a television signal is received a low band signal. To switch the dual tuning circuit 11 shown in Fig. 1 to a state in which a low band television signal is received, a band switching voltage of 5 V is applied, for example, to the first switching terminal 27 A voltage is applied to the first switching diode 22 the second switching diode 23 in the reverse directions and as the first switching diode 23 as the second switching diode 23 becomes a non-continuity state. Therefore, the double tuning circuit 11 shown in Fig. 1 works as an equivalent circuit shown in Fig. 2. In the equivalent circuit shown in Fig. 2, a winding 34 in the primary tuning circuit 11 c india the winding of high band tuning 12 and the low band tuning winding 13 connected in series and a winding 35 in the secondary tuning circuit 11 d indicate the high band tuning winding 16 and the low band tuning winding 17 connected in series . The first coupling winding 20 connected between the ground connection and the connection point of the tuning winding 34 of the primary tuning circuit 11 c and the tuning winding 35 the secondary tuning circuit 11 d determines the coupling state between the circuit of primary tuning 11 c of primary tuning circuit 11 d in a low band. The importance thereof is specified in advance such that the double tuning circuit 11 has a certain transfer characteristic. Therefore, the tuning winding 24 in the primary tuning circuit 11 c and the tuning winding 35 the secondary tuning circuit 11 d does not cause direct inductive coupling. On the other hand, to switch dual tuning circuit 11 shown in FIG. 1 to a state in which a p-band high-band signal is received, a band-switching voltage of 5 V is applied, for example, to the second terminal. switching 29 A voltage is amplified to the first switching diode 22 and to the second switching diode 23 in the forward directions and both switching diodes 22 and 23 are converted into a continuity state. As a result, from the connection point of the high-band tuning winding 12 and the low-band tuning winding 13, the primary tuning circuit 11 c and the connection point of the high-band tuning winding 16 and the band-tuning winding lower 17 the secondary tuning circuit 11 d are connected to ground through the second coupling winding 24 and are also connected to ground through the low-band tuning winding 13 in the primary tuning circuit 11 c and the tuning circuit of low band 17 in the secondary tuning circuit 11 d. Since the circumstances of the two low-band tuning windings 13 and 17 are sufficiently greater than that of the second coupling capacitor 24 and can therefore be ignored, the double tuning circuit 11 shown in Fig. 1 functions as an equivalent circuit shown in Fig. 3. The second coupling winding 24 connected between the ground connection and the connection point of the high-band tuning winding 12 in the primary tuning circuit 11 c and high band tuning winding 16 secondary tuning circuit 11 d determines the coupling state between the primary tuning circuit 11 c and the tuning circuit 11 d in a high band. The importance thereof is specified in advance such that the double tuning circuit 11 has a predetermined transfer characteristic. Therefore, the high-band tuning winding 12 in the primary tuning circuit 11 and the high-band tuning winding 16 of the secondary tuning circuit 11 d do not need to be coupled directly inductively. With the first switching diode 22 of the second switching diode 23 being connected in series by their anodes, a band switching voltage of 5 V is applied, for example, to the second switching terminal 29 for switching to a low band state , and a 5 V band switching voltage is applied, for example, to the first switching terminal 27 for switching to the high band state. Figure 4 shows another double tuning circuit from which it obtains the same advantages as the double tuning circuit 11 shown in Figure 1.

In a double tuning circuit 36, it submits the supply resistors 28, and 30 in the double tuning circuit 11 shown in FIG. 1 and instead the connection point of the first coupling winding 20 and the first blocking capacitor direct current 21 is connected to one end of a supply resistor 37 and the other end thereof is connected to the second switching terminal 29. Switching is made between a high band and a low band in the same way as the circuit double tuning 11 shown in Figure 1. Since the circuit is configured in this manner, the wiring before the first switching diode 22 and the second switching diode 23, and the first switching terminal 27 and second terminal 29 becomes simple .

Claims (3)

NOVELTY OF THE INVENTION CLAIMS

1. - A double tuning circuit comprising: a primary tuning circuit having a high band tuning winding and a low band tuning winding connected in series to one end of each winding; a secondary tuning circuit having a high band tuning winding and a winding is low band tuning connected in series to one end of each winding; a first coupling winding disposed between the ground connection and the connection point at the other end of the low-band tuning winding in said primary tuning circuit is connected to the other end of the low-band tuning winding in said circuit. secondary tuning; a first switching diode and a second switching diode connected in series, disposed between one end of the high band tuning winding in said primary tuning circuit and single end of the high band tuning winding of said secondary tuning circuit; and a second coupling winding disposed between the ground connection and the connection point of said first switching diode said second switching diode, further characterized in that, when a high band television signal is contrasted, said first switching diode is adjusted. and said second switching diode to a continuity state; and when a low band television signal is received, said first switching diode and said second switching diode are set to a non-continuity state.

2. - A dual tuning circuit according to claim 1, further comprising a first switching terminal and a second switching terminal, further characterized in that said first switching diode and said second switching diode are connected in series by their anodes or their cathodes; the anodes are connected to said first switching terminal in the form of direct current coupling; the cathodes are connected to said second switching terminal as direct current coupling; and said first switching diode and said second switching diode are set to a continuity state or a non-continuity state or to a band switching voltage applied to said first switching terminal and said second switching terminal.

3. - A double tuning circuit according to claim 2, further characterized in that said first coupling wire feeder is connected to ground by means of a first direct current blocking capacitor; said second coupling wire feeder is connected to ground by means of a second direct current blocking capacitor; the connection point of said first coupling coil and the first direct current blocking capacitor is connected to said first switching terminal as direct current coupling; and the connection point of said second coupling winding and the second direct current blocking capacitor is connected to said second switching terminal as direct current coupling.