JPS6223150Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The object of the present invention is to prevent abnormal operation of the receiver due to abnormal operation of the switch in a multi-band radio receiver using a multiple push switch for band switching. FIG. 1 shows a conventional example of such a multi-band radio receiver. In Figure 1, 1 is an antenna circuit, 2 is a mixing circuit, 3 is an intermediate frequency amplification circuit, 4 is a detection circuit, 5 is a low frequency amplification circuit, 6 is a speaker, 7 is a local oscillation circuit, and 7a is a local oscillation circuit. 7b is a local oscillation circuit for short wave band SW, 7b is a local oscillation circuit for medium wave band MW, and 7c is a local oscillation circuit for long wave band LW. 8 is a reception frequency display circuit, for example, a digital display for digitally displaying the reception frequency, a counter and a decoder for driving the display;
It consists of an intermediate frequency IF offset circuit, etc. (none of which are shown). A multiple push switch is used as a band changeover switch in the local oscillation circuit section 7. and
Sa1, Sa2, Sa3 are shortwave band switch circuits, Sb1, Sb2, Sb3 are medium wave band switch circuits, Sc1 is a longwave band switch circuit, each switch circuit is a switch key for the corresponding band (not shown, but each band When the contact is set to the lower side, it is in the ON state, and when it is set to the upper side, it is in the OFF state. Therefore, in the case of FIG. 1, the shortwave band reception state is established. VC indicates a variable capacitor of the local oscillation circuit section 7. Conventionally, multiple push switches have been mainly used as band changeover switches for multiband radio receivers due to the relatively large number of circuits and the arrangement of components. This multiple push switch is one in which two or more push switches work together, and only the pressed key is locked in the pressed state.
A device that has a mechanism that turns on the corresponding switch circuit (this state is called the key ON state) and simultaneously turns off all switch circuits controlled by other keys (this state is called the key OFF state). However, depending on the way you operate the push button, the following abnormal conditions may occur. all keys
It becomes OFF. Two or more keys are ON (locked)
do. By the way, in the conventional circuit as shown in FIG. 1, when the push switch operates abnormally, abnormal oscillation occurs in the local oscillation circuit section 7, and the reception frequency display circuit 8 operates abnormally and displays an abnormal frequency, and the speaker 6 outputs an abnormal frequency. There was a risk of noise being generated. FIG. 2 shows a circuit previously proposed by the applicant in Utility Application No. 78748/1983 in order to solve the above-mentioned problems. In the circuit shown in Figure 2, a voltage comparator consisting of an operational amplifier is used to detect abnormal operation of multiple push switches.
It is detected by OP1 and OP2, and the operation of the reception frequency display circuit 8 is stopped when the multiple push switch is in abnormal operation. The circuit shown in Figure 2 is explained in detail in Utility Application No. 1978-78748, so
Further explanation will be omitted here. However, although the circuit shown in FIG. 2 provides satisfactory operation, it has a large number of circuit components and is quite costly in terms of cost. In view of this, the present invention aims to improve the abnormal operation occurring in the circuit shown in Figure 1 without using an expensive circuit as shown in Figure 2. An embodiment of the present invention will be described below. This will be explained according to Figure 3. In Figure 3, Ss-1, Ss-2, Ss-3 are shortwave band switch circuits, SM-1, SM-2,
SM-3 is a switch circuit for medium wave band. And Ss-1, SM-1 are for power switching, Ss-2,
SM-2 is used for injection switching, and Ss-3 and SM-3 are used for switching variable capacitors. In other words, for switching the power supply, the shortwave band switch circuit Ss-1 has the common terminal COM connected to the V _B power supply and OFF. When the side terminal is connected to the common terminal COM of the medium wave band switch circuit SM-1, turn ON.
The side terminals are respectively connected to a shortwave band local oscillation circuit 7a. The medium wave band switch circuit SM-1 for switching the power supply has its OFF side connected to the long wave band local oscillation circuit 7c and its ON side connected to the medium wave band local oscillation circuit 7b. In addition, the shortwave band switch circuit Ss-2 for injection switching is connected to the common terminal COM.
to the mixing circuit 2 and the receiving frequency display circuit 8,
OFF side terminal is switch circuit SM-2 for medium wave band
The ON side terminals are respectively connected to the common terminal COM of the shortwave band local oscillation circuit 7a. Switch circuit SM-2 for medium wave band for injection switching is OFF.
The side terminal is turned ON to the local oscillation circuit 7c for long wave band.
The side terminals are respectively connected to a local oscillation circuit 7b for medium wave band. Furthermore, the short wave band switch circuit Ss-3 for variable capacitor switching has its common terminal COM connected to the non-ground side of the variable capacitor VC, and its OFF side terminal connected to the common terminal COM of the medium wave band switch circuit SM-3.
The side terminal is connected to a shortwave band local oscillation circuit 7a. The medium wave band switch circuit SM-3 for switching the variable capacitor has its OFF terminal connected to the long wave band local oscillation circuit 7c and its ON side terminal connected to the medium wave band local oscillation circuit 7b. FIG. 4 is a diagram showing a multiple push switch for operating the circuit of FIG. 3. In Fig. 4, SS, SM, and SL are push switches for short wave band, medium wave band, and long wave band, respectively.
KS, KM, and KL are the switches* of the push switch, and only the pressed key is locked in the depressed state, and at the same time, the other switch keys are released from the locked state. When the switch key KS of the short wave band push switch SS or the switch key KM of the medium wave band push switch SM is pushed and locked, the corresponding band switch circuits Ss-1 and Ss- shown in Fig. 3 are activated.
2, Ss-3 or SM-1, SM-2, SM-3
Set to ON side. Also, as is clear from Fig. 3, there is no switch circuit for the long wave band which is set to the ON side by the push operation of the switch key KL of the push switch SL for the long wave band, and the push switch SL for the long wave band is set to the ON side by the push operation of the switch key KL. It serves as a dummy switch to turn on and off the push switch SS for the band, the switch key KS for the SM, and the lock for the KM. Furthermore, in the circuit of Fig. 3, the push switches SS, SM, and SL are connected as described later.
1 in the predetermined priority order even when there is an abnormal operation.
Only the local oscillation circuits of two bands operate, and only one band is in the receiving state. Next, the operation of the circuit shown in FIG. 3 controlled by the push switch shown in FIG. 4 will be explained. When only the switch key KS of the shortwave band push switch SS is pushed and locked (the state shown in Figure 4), only the shortwave band switch circuits SSs-1, Ss-2, and Ss-3 are activated.
Set to ON side. Therefore, at this time, power is supplied to the shortwave band local oscillation circuit 7a via the switch circuit Ss-1, and the variable capacitor is supplied to the shortwave band local oscillation circuit 7a via the switch circuit Ss-3.
VC is connected, and the local oscillation output is injected into the mixer circuit 2 via the switch circuit Ss-2, resulting in a shortwave band reception state. Similarly, when only the switch key KM of the medium wave band push switch SM is locked in the pushed state, the medium wave band switch circuit
Only SM-1, SM-2, and SM-3 are set to the ON side to enter the medium wave band reception state. Also, when only the switch key KL of the longwave band push switch SL is locked in the pushed state, the shortwave band switch circuit Ss
-1, Ss-2, Ss-3 and medium wave band switch circuits SM-1, SM-2, SM-3 are all set to the OFF side to enter the long wave band receiving state. The above is a description of the case where the push switch is operating normally. Next, the case where the push switch is operating abnormally will be explained. When the switch keys KS, KM, and KL of all push switches SS, SM, and SL are locked in the pushed state. In this case, the shortwave band switch circuit Ss−
1, Ss-2, Ss-3 and medium wave band switch circuits SM-1, SM-2, SM-3 are all set to the ON side, and the short wave band local oscillation circuit 7a operates, but the medium wave band Band local oscillation circuit 7b
The power supply to the medium wave band local oscillation circuit 7b and the variable capacitor VC is cut off by the switch circuit Ss-3, and the medium wave band local oscillation circuit 7b and the variable capacitor VC are disconnected from each other by the switch circuit Ss-1. Since the communication with the mixing circuit 2 is cut off by the switch circuit Ss-2, the short wave band is preferentially received. When the shortwave band and medium wave band push switches SS and SM switch keys KS and KM are locked in the pressed state. As in this case, short wave band switch circuits Ss-1, Ss-2, Ss-3 and medium wave band switch circuits SM-1, SM-2, SM-3
are both set to the ON side, and the shortwave band is received preferentially. When the switch keys KS and KL of the shortwave band and longwave band push switches SS and SL are locked in the pressed state. In this case, the shortwave band switch circuit Ss−
1, Ss-2, Ss-3 are ON side, medium wave band switch circuit SM-1, SM-2, SM-3 is OFF
Since the shortwave band is set to the side, the shortwave band is received preferentially. When the switch keys KM and KL of the medium wave band and long wave band push switches SM and SL are locked in the pressed state. In this case, the shortwave band switch circuit Ss−
1, Ss-2, Ss-3 are OFF, medium wave band switch circuit SM-1, SM-2, SM-3 is ON
Since it is set to the side, the medium wave band is received preferentially. When the switch keys KS, KM, and KL of any of the push switches SS, SM, and SL are not locked in the pushed position. In this case, the shortwave band switch circuit Ss−
1. Ss-2, Ss-3 and medium wave band switch circuits SM-1, SM-2, SM-3 are all OFF.
set to receive the long wave band. If the push switch malfunctions in this way, only one of the shortwave band, medium wave band, and longwave band will be in the receiving state in the priority order. When this is summarized, the results are as shown in Table 1.

[Table] Therefore, even if the push switch malfunctions, it is possible to prevent abnormal oscillation in the local oscillation circuit or malfunction of the reception frequency display circuit. In the circuit shown in FIG. 3, the explanation of the switch circuits in the antenna circuit 1 and the mixing circuit 2 is omitted, but the antenna circuit 1 has a variable capacitor switching, and the mixing circuit 2 has a signal input switching. Therefore, if these switch circuits are given the same priority as determined by the local oscillation circuit during abnormal operation of the push switch, not only the operation of the local oscillation circuit when the push switch is abnormal, but also the operation of the receiver The entire operation can be made to work normally. In addition, in the embodiments shown in Figs. 3 and 4, one dummy switch is added to balance the push switches, but this does not pose a problem in terms of cost, and it is not necessary to use a large-scale circuit like the circuit shown in Fig. 2. Cost increase can be improved. As described above, according to the present invention, in a multi-band receiver using multiple push switches, abnormal oscillation of the local oscillator circuit and abnormal operation of the receiving frequency display circuit, etc., which may occur when the multiple push switches operate abnormally, can be avoided. can be realized at low cost with a simple circuit configuration.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing a conventional multi-band radio receiver, FIG. 3 is a block diagram showing a multi-band radio receiver according to the present invention, and FIG. 4 is a block diagram showing a multi-band radio receiver according to the present invention.
FIG. 3 is a diagram showing a multiple push switch for operating the circuit shown in the figure. SS, SM, SL... Push switch, Ss-
1, Ss-2, Ss-3, SM-1, SM-2, SM-
3...Switch circuit.

Claims (1)

[Scope of utility model registration request] In a multi-band radio receiver using multiple push switches, adjacent switch circuits of the multiple push switches are connected in series to form an upper switch circuit and a lower switch circuit, respectively, and the upper switch circuit is turned on. In this case, this switch circuit applies power to the band corresponding to the upper switch circuit and cuts off the power to the band corresponding to the lower switch circuit, thereby bringing the band corresponding to the upper switch circuit into the receiving state. , when the upper switch circuit is off, the upper switch circuit cuts off power to the band corresponding to the upper switch circuit and supplies power to the band corresponding to the lower switch circuit, thereby corresponding to the lower switch circuit. A multi-band radio receiver characterized in that a band is placed in a receiving state, and a band corresponding to an upper switch circuit that is in an on state is placed in a receiving state preferentially.