JPH0125033Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a speaker switching circuit for an audio device having two speaker connection terminals, A and B.

In an audio device with two speaker connection terminals, A and B, a switch is used to switch between A, B, and A+B. In the case of A+B, two speakers for the same channel are connected in parallel to each other. was. In this way, if two speakers are connected in parallel and the speaker has a low impedance, for example 4Ω, the impedance will be 1/2 of the output of the output amplifier.
becomes 2Ω. Therefore, when used at high output,
I suffered damage to the output transistor in the output amplifier. Therefore, in the case of A+B, it is conceivable to connect two speakers in series. When connected in series, the impedance is doubled and the problem of damage to the output transistor is eliminated. On the other hand,
Regarding measures to eliminate RF interference waves, in the case of parallel connection,
It is sufficient to insert a capacitor between the terminals of each speaker, but in the case of series connection, the suspension of the speaker circuit for switching becomes long, which causes the problem that this serves as an antenna and RF interference waves enter the circuit. arise.

The present invention was developed to solve the above contradictory problems, and in the case of A+B, the speakers are connected in series, and the RF interference waves are dissipated to the ground through the shortest distance.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

1 is an R channel signal input terminal, 2 is an L channel signal input terminal, 3 and 4 are output amplifiers for the R channel and L channel, respectively, and 5 and 6 are RF
This is a filter for preventing interference waves from entering. These are connected to a speaker connection terminal group 8 via a changeover switch 7.

The changeover switch 7 has two first and second switches 9 and 10 that are interlocked with each other for the A side, and four first, second, third, and fourth switches that are interlocked with each other for the B side. Switch 11, 12, 13, 14
has. These switches have a common contact in the center.
The CO is a slide type with an ON contact on the right side (turns on the speaker) and an OFF contact on the left side (turns on the headphone). However, it may be a rotary type instead of a slide type. The speaker connection terminal group 8 has R channel speaker connection terminals 15, 16 and L channel speaker connection terminals 17, 18 on the A side, and R channel speaker connection terminals 19, 20 and L channel speaker connection terminals on the B side. It has 21 and 22.

The first switch 9 on the A side has a common contact CO,
The on contact ON is connected to one of the L channel speaker connection terminals 17 and 18 on the A side of the speaker connection terminal group 8, and the off contact OFF is connected to the first switch 11 on the B side. Connected to common contact CO.

The second switch 10 on the A side has a common contact CO connected to the filter 5 of the R channel, and an ON contact ON connected to one 15 of the R channel speaker connection terminals 15 and 16 on the A side of the speaker connection terminal group 8. , the off contact OFF is connected to the common contact CO of the third switch 12 on the B side.

The first switch 11 and the second switch 1 on the B side
2, the ON contacts ON and ON are short-circuited to each other and are connected to one 22 of the L channel speaker connection terminals 21 and 22 on the B side of the speaker connection terminal group 8, and the common contact CO of the second switch 12 is connected to the A side. L
The other 1 of channel speaker connection terminals 17 and 18
7 and the off contact of the second switch 12
OFF is grounded.

The third switch 13 and the fourth switch 1 on the B side
4 has on-contacts ON and ON shorted together, and is connected to one 19 of the R channel speaker connection terminals 19 and 20 on the B side of the speaker connection terminal group 8,
The common contact CO of the fourth switch 14 is connected to the other one of the R channel speaker connection terminals 15 and 16 on the A side, and the off contact OFF of the fourth switch 14 is grounded.

Among the speaker connection terminal group 8, terminals 16,
20 and 17 and 21 are coupled through capacitors 23 and 24, respectively, and the terminals 20 and 21 are grounded to the printed circuit board and are also grounded to the chassis via a capacitor 25. Also,
Between terminals 15 and 16, between 17 and 18, 19 and 20
Speakers 26 and 2 are installed between 21 and 22, respectively.
7, 28, and 29 are connected, and noise removal capacitors 30, 31, 32, and 33 are also connected.

Next, the operation of the circuit configuration as described above will be explained.

(1) In the case of A+B, the first and second switches 9 and 10 on the A side and the first, second, third, and fourth switches on the B side
All switches 11, 12, 13, and 14 are connected to the ON contact (ON) side (as shown). In this state, the L channel input signal is transmitted through terminal 2 → output amplifier 4 → filter 6 → A side first switch 9.
→A side L channel speaker 27→B side second switch 12→B side L channel speaker 29→
The R channel input signal flows from terminal 1 to output amplifier 3 to filter 5 to A side second switch 10 to A side R channel speaker 2.
6→B-side fourth switch 14→B-side R channel speaker 28→ground. Therefore, the L channel signal is reproduced from the speakers 27 and 29, and the R channel signal is reproduced from the speakers 26 and 28.
The channel's signal is played back. In this case, L
Channel speaker 27 → B side second switch 12 → B side L channel speaker 29 are grounded via the capacitor 24 at the shortest distance, and R channel speaker 26 → B side fourth switch 14 → B side R channel speaker 2
8 is grounded via a capacitor 23 at the shortest distance. Therefore, the connection to the speaker circuit is
RF interference is prevented from entering.

(2) In the case of A only, the first and second switches 9 and 10 on the A side remain on the ON contact (ON) side, and the B
1st, 2nd, 3rd, and 4th switches 11, 1 on the side
Switch 2, 13, and 14 to the off contact (OFF) side. As a result, the L channel input signal becomes
Terminal 2 → Output amplifier 4 → Filter 6 → A side first switch 9 → A side L channel speaker 2
7 → B side second switch 12 → ground, and the R channel input signal flows from terminal 1 →
Output amplifier 3 → Filter 5 → A side second switch 10 → A side R channel speaker 26 → B
The signal flows in the order of the fourth switch 14 on the side and then ground, and the L channel speaker 29 and R channel speaker 28 on the B side are separated from the A side.

(3) In the case of B only, the first, second, third, and fourth switches 11, 12, 13, and 14 on the B side are connected to the ON contact (ON) side, and the first and second switches on the A side are connected to the ON contact (ON) side. Switch 9 and 10 to the off contact (OFF) side.
As a result, the L channel input signal is transferred to terminal 2.
→ Output amplifier 4 → Filter 6 → A side first switch 9 → B side first switch 11 → B side L channel speaker 29 → Ground, and the R channel input signal flows from terminal 1 → output amplifier 3 →
Filter 5 → A side second switch 10 → B side third
Switch 13 → B side R channel speaker 28
->Ground, and the L channel speaker 27 and R channel speaker 26 on the A side are separated from the B side.

Since the present invention is configured as described above, in the case of A+B connection, the two speakers are connected in series with each other, so even if a low impedance speaker is used, the impedance will be low with respect to the output amplifier. Even when used at high output, the internal transistors will not be damaged. Moreover, since they are connected in series, even if the speaker circuit has a long suspension, the high frequency is grounded via the capacitor, so RF interference waves will not enter the circuit.

[Brief explanation of the drawing]

The figure is an electrical circuit diagram showing one embodiment of the speaker switching circuit of the audio device according to the present invention. 1...R channel signal input terminal, 2...L channel signal input terminal, 3, 4...output amplifier,
5, 6...Filter, 7...Selector switch, 8...
...Speaker connection terminal group, 9...A side first switch, 10...A side second switch, 11...B side first switch, 12...B side second switch, 13...
...B side third switch, 14...B side fourth switch, 15, 16, 17, 18, 19, 20, 2
1, 22...Speaker connection terminal, 23, 24, 2
5... Capacitor, 26, 27, 28, 29...
Speaker, 30, 31, 32, 33... capacitor.

Claims (1)

[Claims for Utility Model Registration] 1. The speaker connection terminal has two systems, A and B.
B, A+B, there is a changeover switch for connecting speakers for the same channel in series when A+B, and an RF switch interposed between the connection terminals of the speakers for the same channel, one end of which is connected to ground. and a capacitor for removing interference waves, and the changeover switch has first and second switches that are interlocked with each other for the A side, and first, second, third, and fourth switches that are interlocked with each other for the B side. has a switch, and said A
The first switch on the side has a common contact coupled to the input terminal of the L channel, an on contact coupled to one of the L channel speaker connection terminals on the A side, an off contact coupled to the common contact of the first switch on the B side, and The second switch on the side has a common contact connected to the input terminal of the R channel, and an on contact connected to the R channel on the A side.
It is coupled to one of the channel speaker connection terminals, the off contact is coupled to the common contact of the B side third switch, and the on contact of the B side first switch is coupled to the B side third switch.
connected to the on contact of the second switch on the side, and
The second switch on the B side is connected to one of the L channel speaker connection terminals on the side, and the common contact is connected to the L channel speaker on the A side.
The third switch on the B side is connected to the other channel speaker connection terminal, the off contact is grounded to the earth line of the circuit, and the on contact is connected to the fourth switch on the B side.
R connected to the on contact of the switch and on the B side
The B-side fourth switch is coupled to one of the channel speaker connection terminals, and the common contact is coupled to the other of the A-side R channel speaker connection terminals;
The off contact is grounded to the circuit earth line, and B
The other of the R and L channel speaker connection terminals on the side are connected to each other and grounded to the earth line of the circuit and also grounded to the chassis via a capacitor, and the other of the L channel speaker connection terminal on the A side is connected to the L channel on the B side. The other of the speaker connection terminals is connected to the other side of the R channel speaker connection terminal on the B side via the RF interference wave elimination capacitor, and the other side of the A side R channel speaker connection terminal is connected to the other side of the B side R channel speaker connection terminal via the RF interference wave elimination capacitor. Speaker switching circuit for audio equipment connected to 2. The first and second switches for the A side and the first, second, third, and fourth switches for the B side are slide switches or rotary switches for switching the speaker of the audio device according to claim 1 of the utility model registration claim. circuit.