JPH0125032Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a speaker switching circuit, and particularly has a simplified circuit configuration. When listening to the same music in two different places, for example, a study and a living room, two speakers placed in the study and the living room are driven by a single output of an amplifier. In this case, the speakers are driven in series to reduce impedance to suppress heat generation and ensure safety. Further, in such a speaker system, since it is often desired to drive only one speaker, it is necessary to be able to drive the speaker selectively. Incidentally, in order to drive the two speakers in series and alternatively, a speaker switching circuit as shown in FIG. 1 has been proposed. In FIG. 1, 1 is one output terminal (line output terminal) of the amplifier, and the output of the amplifier is supplied to this output terminal 1. This output terminal 1 is connected to the common contact 2c of the changeover switch 2,
Fixed contacts 2a and 2b of the changeover switch 2 are connected to one terminal 3a of the speaker 3 and a common contact 4c of the other changeover switch 4, respectively. Here, the speaker 3 is placed in a study, for example. Also, 5 is the other output terminal (ground terminal) of the amplifier.
The output terminal 5 is connected to one terminal 6b of the speaker 6 and also to a fixed contact 7b of the changeover switch 7. Here, the speaker 6 is placed, for example, in a living room. The common contact 7c of the changeover switch 7 is connected to the other terminal 3b of the speaker 3 in the study, and the other fixed contact 7a is connected to the other terminal 3b of the speaker 3 in the study.
are connected to the other fixed contact 4a of the changeover switch 4 and to the terminal 6a of the speaker 6 in the living room, respectively.
Note that the other fixed contact 4b of the changeover switch 4 is in an electrically floating state. In such a conventional speaker switching circuit, the switching states of the switching switches 2, 4, and 7 are as shown in Table 1.

[Table] Therefore, if you want to listen to music etc. only in the study, for example, change the common contacts 2c, 4c, 7c of the changeover switches 2, 4, 7 to the fixed contacts 2a, 4b, 7, respectively.
b, and supply the output of the amplifier only to the speaker 3 in the study. Also, if you want to listen to music etc. only in the living room, for example, connect the common contacts 2c, 4c, 7c of the changeover switches 2, 4, 7 to the fixed contacts 2b, 4a, 7a, respectively, and listen to the speakers 6 only in the living room. What is necessary is to supply the output of the amplifier. Furthermore, if you want to listen to music etc. in both the study and the living room, for example, each common contact 2c, 4c, 7c of the changeover switches 2, 4, 7 can be connected to the fixed contact 2, respectively.
a, 4a, and 7a, and supply the output of the amplifier to the speakers 3 and 6 in series. still,
In order to prevent the speakers 3 and 6 in the study and the living room from being loud, the common contacts 2c, 4c, and 7c of the changeover switches 2, 4, and 7 should be connected to fixed contacts 2, for example.
b, 4b, and 7b, respectively. On the other hand, in such a conventional example, as is clear from Table 1, the changeover switches 2, 4, and 7 are all essential members, and even if any of the changeover switches 2, 4, and 7 are omitted, the speakers 3 and 6 are Problems occur in switching. That is, the changeover switch 2 is omitted, and instead, for example, the contacts 2a and 2c are short-circuited, and the contacts 2b and 2c are short-circuited.
If the wires are connected so that the space between the speakers 2c and 2c is open, it becomes impossible to drive only the speaker 6 or stop driving both the speakers 3 and 6. Also, the changeover switch 4 is omitted, and instead, for example, the contacts 4a, 4 are used.
If the wires are connected so that the contacts 4b and 4c are short-circuited and the contacts 4b and 4c are opened, it becomes impossible to drive only the speaker 3. Furthermore, the changeover switch 7 is omitted, and for example, the contacts 7a and 7c are short-circuited, and the contacts 7b and 7c are short-circuited.
If the wires are connected so that the space between 7c is open, it becomes impossible to stop driving both the speakers 3 and 6. For this reason, in the conventional example, the number of changeover switches, that is, the number of contacts, is large, which results in an increase in costs (material costs, mounting space) and output power loss, and also requires manufacturing work such as wiring work. I was worried that it would become complicated. The present invention has been devised in view of this point, and aims to provide a speaker switching circuit that can reduce the number of contacts. Hereinafter, one embodiment of the speaker switching circuit of the present invention will be described with reference to FIG. In FIG. 2, parts corresponding to those in FIG. 1 are given the same reference numerals, and detailed explanation thereof will be omitted. In Figure 2, one output terminal 1 of the amplifier
one fixed contact 11 of the first changeover switch 11
a and one terminal 3a of the speaker 3, respectively. Further, the other terminal 3b of the speaker 3 is connected to the common contact 11c of the first changeover switch 11 and one terminal 6a of the other speaker 6, respectively. Also, the other terminal 6b of the speaker 6 is connected to the second selector switch 1.
2, and the other fixed contact 12a of the second changeover switch 12.
and the common contact 12c respectively to the first changeover switch 1
1 and the other output terminal 5 of the amplifier. According to this configuration, the speaker switching control performed by the conventional speaker switching circuit (FIG. 1) can be performed using two changeover switches (instead of three in the past). That is, the first and second changeover switches 11,1
Depending on the switching state of the amplifier 2, the output of the amplifier is alternatively supplied to the speakers 3 and 6 as shown in Table 2, or is supplied in series to the speakers 3 and 6, and further the output of the amplifier to the speakers 3 and 6 is The supply of outputs is both stopped. For example, in the state shown in FIG. 2, each common contact 1 of the first and second changeover switches 11 and 12
When 1c and 12c are connected to fixed contacts 11a and 12b, respectively, a current flows as shown by the broken line, and only the speaker 6 is driven, so that music etc. can be heard in the living room.

[Table] As described above, according to the speaker switching circuit of the present invention, the first and second switching switches 11 and 12 have three contacts, that is, the speakers 3 and 6 have six contacts.
Alternative driving of the speakers 3 and 6, series driving of both the speakers 3 and 6, and stopping of driving of both the speakers 3 and 6 can be controlled by switching. Therefore, compared to conventional speaker switching circuits, costs are reduced by reducing the number of switching switches, output power loss due to contacts is reduced,
There are advantages in that the mounting space can be reduced due to the reduction in the number of changeover switches, the wire wiring work can be simplified, and the material cost for the wire can be reduced. It goes without saying that the present invention is not limited to the above-described embodiments, and that various other configurations may be adopted without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional speaker switching circuit, and FIG. 2 is a block diagram showing an embodiment of the speaker switching circuit of the present invention. 1 and 5 are amplifier output terminals, 3 and 6 are speaker terminals, 3a, 3b, 6a, and 6b are speaker terminals,
11 and 12 are changeover switches; 11a and 11b are fixed contacts of the changeover switch 11; 11c is a common contact of the changeover switch 11; 12a and 12b are fixed contacts of the changeover switch 12; and 12c is a common contact of the changeover switch 12.

Claims (1)

[Scope of claims for utility model registration] The first
and a second changeover switch, and first and second changeover switches in which the signals from the amplifier are selectively switched by the first and second changeover switches.
a speaker, one output terminal of the amplifier is connected to one terminal of the first speaker and also connected to one fixed contact of the first changeover switch, and a common switch of the first changeover switch. connecting a contact to the other terminal of the first speaker and to one terminal of the second speaker, and connecting the other output terminal of the amplifier to a common contact of the second switch;
Connecting the other fixed contact of the second changeover switch to the other terminal of the second switch,
A speaker switching circuit characterized in that one fixed contact of the second switching switch is connected to the other contact of the first switching switch.