JPH0350904A - Low frequency circuit - Google Patents

Abstract

PURPOSE:To allow an optical speaker to connect to the low frequency circuit in addition to an exclusive low or high frequency speaker by selecting between an of an LPF and an input signal to send the selected signal to a low frequency amplifier and selecting between an output of an HPF and the input signal to send the selected signal to the low frequency amplifier. CONSTITUTION:When switches 3a, 3b are thrown to the position of filter side, a low frequency input signal A is given to output terminals C, D via a low pass filter 1a and a high pass filter 2a and low frequency amplifiers 4a, 5a, the output terminal C is speaker terminal exclusively for a low sound frequency and output terminal D is a speaker terminal exclusively for a high sound frequency. On the other hand, when the switches 3a, 3b are thrown directly to the input signal A not through the filters 1a, 2a, the output terminals C, D of the low frequency amplifiers 4a, 5a are output terminals for a flat signal. Thus, the output of the low frequency amplifiers exclusive for low and high frequencies and two systems of flat outputs are provided and an optional speaker is connected in addition to exclusive low and high sound frequencies.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a low frequency circuit having a plurality of low frequency and high frequency amplifier circuits.

Conventional technology In recent years, radio cassette players have been equipped with CD players to improve sound quality, and multi-amplifiers, which were previously used in high-end amplifiers, are now used to amplify each low-range and high-range signal separately. It's starting to look like this.

Problems to be Solved by the Invention However, when using the multi-amplifier described above in a radio cassette player, it is necessary to provide a dedicated headphone amplifier and a headphone/speaker selection switch, which requires an expensive circuit configuration, and also requires a speaker output terminal. In radio cassette players,
The problem was that only dedicated speakers could be used.

In view of the above-mentioned problems, the present invention provides a low frequency circuit that performs headphone/speaker switching without providing a dedicated headphone amplifier and also allows use of speakers other than the dedicated speaker.

Means for Solving the Problems In order to solve the above problems, the low frequency circuit of the present invention includes a low pass filter that passes the low frequency range of a low frequency input signal;
a high-pass filter that passes high frequencies of the input signal;
The present invention is characterized in that it includes switch means for switching between each filter output and the input signal that does not pass through the filter, and a low frequency amplifier that amplifies each of the low-frequency and high-frequency signals.

Further, the low frequency circuit of the present invention includes a low frequency amplification circuit consisting of a low pass filter and a low frequency amplifier that selectively amplify the low frequency range of a low frequency input signal, and a high frequency circuit consisting of a high pass filter and a low frequency amplifier that selectively amplify the high frequency range of the low frequency input signal. When a headphone plug is inserted into the headphone jack, the signal from the switch that operates in conjunction with the insertion of the plug or the DC voltage superimposed on the output signal is transmitted through the headphone plug and the grounding piece of the headphone jack. a muting circuit that blocks signals from amplifier circuits that are not connected to the headphone jack, and a switching circuit that allows the filter of one of the amplifier circuits to pass through, using the signal from the circuit that is configured to supply the headphone jack. It is.

Function: With the above-described configuration, the present invention can make it possible to use a speaker other than the dedicated speaker by switching a switch. In addition, when using headphones, the present invention provides a signal from a switch linked to the headphone plug or
The direct current voltage superimposed on the output signal is taken out via the headphone plug and headphone jack ground piece, which blocks the signal from the amplifier circuit that is not connected to the headphone jack, and allows the signal to pass through the filter of one amplifier circuit. A flat headphone output is obtained, and headphone/speaker switching can be performed without installing a dedicated headphone amplifier.

EXAMPLE A low frequency circuit according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a block diagram of a low frequency circuit in an embodiment of the present invention. In FIG. 1, a low frequency input signal A is connected through a low pass filter 1a, a low frequency amplifier 4a, and an output terminal C to a speaker. Further, the input signal A is connected to a high-pass filter 2a, a low-frequency amplifier 5a, an output terminal C, and a speaker. On the other hand, the switch 3a is inserted before the low frequency amplifier 4a in order to selectively connect the output of the low pass filter 1a and the input signal A to the low frequency amplifier 4a. Switch 3b is high pass filter 2
a and the input signal selectively to a low frequency amplifier 5a.
It is inserted before the low frequency amplifier 5a in order to connect to the low frequency amplifier 5a.

The operation of the low frequency circuit configured as above will be explained.

When the switches 3a, 3b are connected to the filter side, the low frequency input signal A is applied to each filter 1a.

2a and low frequency amplifiers 4a and 5a to output terminals C and D.
The output terminal C becomes a low-frequency-only Nupi power terminal, and the output end becomes a high-frequency speaker terminal. On the other hand switch 3a
, 3b is the filter 1a.

When directly connected to the input signal A that does not pass through 2a, the output terminals C and D of the low frequency amplifiers 4a and 5a become flat signal output terminals.

As described above, according to this embodiment, there is a low-pass filter that passes the low frequency range of the low-frequency input signal, a high-pass filter that passes the high frequency range of the input signal, and the respective filter outputs and the input signal that does not pass through the filter. and a switch means for switching the low range.

By providing a low-frequency amplifier that amplifies each signal in the high-frequency range, it is possible to obtain the output of the low-frequency amplifier dedicated to the low-frequency and high-frequency ranges with a switch, and also to provide two flat output systems. , any speaker can be connected in addition to the dedicated high-frequency speaker.

A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram of a low frequency circuit showing a second embodiment of the present invention, and FIG. 4 is a wiring diagram of a headphone jack. Although the figure shows the case of left and right stereo, only one channel will be explained. The low frequency input signal A is passed through a low pass filter 1a and a muting circuit 6a.
, are connected to a low frequency dedicated speaker 8a via a low frequency amplifier 4a.

Further, the input signal A is passed through a high pass filter 2a.

The signal is connected to a high frequency dedicated speaker 9a through a switching circuit 7a between a filter output and an unfiltered input signal, a low frequency amplifier 5a, and a headphone jack 11. Further, the output of the low frequency amplifier 6a is connected to the headphone contact 11c of the headphone jack 11 via a headphone volume adjustment resistor 12a. Note that the headphone jack 11 for switching between speakers and headphones is shown in FIG. 4, but since it is already widely used, its explanation will be omitted. On the other hand, the input signal B is also connected in the same manner as described above, so its explanation will be omitted. A signal from the switch 1°, which operates in conjunction with the insertion of the headphone plug into the headphones 11, is connected to the muting circuit 8a and the switching circuit a.

As described above, according to this embodiment, there is a low-pass amplifier that selectively amplifies the low frequency range of a low-frequency input signal, and a low-frequency amplifier circuit that includes a low-frequency amplifier, and a high-pass filter that selectively amplifies the high frequency range of the low-frequency input signal. a headphone jack equipped with a high-frequency amplification circuit, a means for switching the output of one of the amplification circuits between headphones and speakers, and a switch that works with the headphone plug; By providing a muting circuit that blocks signals from amplifier circuits that are not connected to the jack and a switching circuit that passes the filter of one amplifier circuit, it becomes a dedicated amplifier for low and high frequencies when headphones are not used. ,or,
When using headphones, a switch that works in conjunction with the headphone plug activates the muting circuit of the amplifier circuit that is not connected to the headphone jack to turn off the output, and also passes the noise of the amplifier circuit connected to the headphone jack to create a flat sound. You can get headphone output.

A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of a low frequency circuit showing a third embodiment of the present invention. Components with the same reference numerals in the figure are similar to those in FIG. 2.

What differs from the configuration in Figure 2 is the headphone jack 11.
The output of the low frequency amplifier 5a is connected via the coupling capacitor 13a, the power source is connected via the resistor 16, and the ground piece 11g of the headphone jack 11 is connected to the capacitor 1.
4 to ground, and the voltage across the capacitor 14 to the muting circuit 6 &.

eb is used as a control signal to the switching circuits 7a and 7b.

The operation of the low frequency circuit configured as described above will be explained below.

When headphones are not used, the output of the low frequency amplifier 6a is connected to the contact 11a of the headphone jack 11.

It is connected to the speaker via 11b and operates as a low frequency amplification circuit for each of the low and high frequencies. Here, the resistor 15 connected to the power supply has a sufficiently larger resistance than the spill force output, so it does not have any influence.

On the other hand, when using headphones, when the headphone plug is inserted, the output of the low frequency amplifier 6a is connected to the capacitor 13a, the resistor 12a, and the headphone terminal 11c.

It is supplied to the headphones through the headphone plug, and the ground side of the headphones is connected to the ground piece 11q of the headphone jack.
, and are grounded through a capacitor 14, forming a headphone amplifier circuit. On the other hand, a power supply connected via a resistor 16 connected after the capacitor 13a is superimposed on the low frequency signal, and is connected to the headphone jack 11 via the headphones.
The voltage appears as a voltage across the capacitor 140 connected to the ground piece 14 of the muting circuit 6a of the low frequency amplifier circuit.

It is connected as a control signal to the switching circuit 7a that passes the high-pass filter 2a, and the speaker output of the low-pass amplifier circuit is switched to O.
At the same time, the amplifier circuit connected to the headphone jack 11 is switched to have flat characteristics.

As described above, the headphone jack is equipped with a means for switching the output of one amplifier circuit between headphones and speakers;
Connect the output of one of the amplifier circuits to the power supply via a resistor, and ground the ground side of the headphone jack with a capacitor. By providing headphone/speaker switching means that uses a control signal to control the muting circuit and the filter switching circuit of one of the amplifier circuits, the same effect as in the second embodiment can be obtained.

Note that the explanation has been given only for one low frequency input signal A, but since the same is true for the input signal B, the explanation will be omitted.

Also, the second. In the third embodiment, the high frequency amplifier circuit is connected to the headphone jack, but the low frequency amplifier circuit may be connected to the headphone jack.

Effects of the Invention As described above, the present invention includes a low-pass filter that passes a 1-degree range of a low-frequency input signal, a high-pass filter that passes a high-frequency range of the input signal, and a filter output of each filter and the input that does not pass through the filter. By providing a switch means for switching the signal and a low frequency amplifier for amplifying the low frequency and high frequency signals respectively, the output of the low frequency amplifier dedicated to the low frequency and high frequency ranges and the flat output can be changed by the switch. A system can be provided, and any speaker can be connected in addition to the dedicated speaker consisting of low-frequency and high-frequency speakers.

In addition, there is a low-frequency amplification circuit consisting of a low-pass filter and low-frequency amplifier that selectively amplifies the low-frequency range of the low-frequency input signal, a high-frequency amplification circuit consisting of a high-frequency amplifier and a low-frequency amplifier that selectively amplifies the high frequency range, and a headphone jack. When a headphone plug is inserted into the headphone plug, a signal from a switch that operates in conjunction with the insertion of the plug, or a circuit configured to supply a DC voltage superimposed on the output signal via the ground piece of the headphone plug or headphone jack. By providing a muting circuit that blocks the signal from the amplifier circuit that is not connected to the headphone jack, and a switching circuit that allows the signal to pass through the filter of the booster circuit, the low frequency signal is suppressed when headphones are not in use.

There is no dedicated amplification circuit for each high frequency range, and when using headphones, the output of the amplification circuit that is not connected to the headphone jack is turned off at the same time as the headphone plug is inserted.
At the same time, the output of the amplifier circuit connected to the headphone jack can be made into a flat headphone output, and headphone/speaker switching can be performed without providing a dedicated headphone amplifier.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a low frequency circuit according to a first embodiment of the present invention, FIG. 2 is a block diagram of a low frequency circuit according to a second embodiment of the present invention, and FIG. 3 is a block diagram of a low frequency circuit according to a second embodiment of the present invention. A block diagram of the low frequency circuit in the embodiment, Figure 4 is similar to Figures 2 and 3.
It is a wiring diagram of the headphone jack shown in the figure. 1a, 1b...Low pass filter, 2a, 2b
...High pass filter, 3a, 3b...
・Choice switch, 4a, 4b, 5a, 5b...
...Low frequency amplifier, 6a, sb...Muting circuit, 7a, 7b...Switching circuit, 10
......Interlocking switch, 11...Headphone jack, 14...Capacitor, 16...
···resistance.

Claims (3)

[Claims] (1) Switching between a low-pass filter that passes the low frequency range of the low frequency input signal, a high pass filter that passes the high frequency range of the low frequency input signal, and the respective filter outputs and the low frequency input signal that does not pass through the filter. A low frequency circuit comprising a switch means and a low frequency amplifier that amplifies each of the low frequency and high frequency signals selected by the switch means. (2) a low-pass filter that selectively amplifies the low-frequency range of a low-frequency input signal; a low-pass amplification circuit consisting of a low-frequency amplifier; and a high-pass filter that selectively amplifies the high-frequency range of the low-frequency input signal;
A headphone jack has a high-frequency amplification circuit consisting of a low-frequency amplifier, a means for switching the output of one of the amplification circuits to a headphone output and a speaker output, and a switch that is linked to the insertion and removal of the headphone plug, and a signal from the switch causes the headphones to be connected to the headphone jack. A low frequency circuit characterized by comprising a muting circuit that blocks signals from amplifier circuits that are not connected to a headphone jack when the circuit is inserted into a headphone jack, and a switching circuit that passes the filter of one of the amplifier circuits. (3) The output side of a headphone jack equipped with means for switching the output of one amplifier circuit to a headphone output and a speaker output and the output of one amplifier circuit are connected to a power source via a resistor, and the headphone jack is grounded. Headphone/speaker switching means whose side is grounded with a capacitor and which generates a control signal to control the muting circuit of the other amplifier circuit and the filter switching circuit of one amplifier circuit via the headphones when the headphone plug is inserted. 2. The low frequency circuit according to claim 1, further comprising a low frequency circuit.