JPS6093900A - Disconnection detector of speaker input line - Google Patents

Abstract

PURPOSE:To detect surely disconnection of an input line by detecting a line resistance of a speaker input line by means of a disconnection detecting circuit and comparing the resistance with a reference value. CONSTITUTION:A speaker 2 is driven by an amplifier 1. The disconnection detecting circuit 6 consists of the 1st comparator giving an output when a line voltage V is 2E/3 or over for two speakers 2 as an object, the 2nd comparator giving an output when V=E and a display device operated by receiving the output of the comparators. Thus, it is detected that either of the two speakers 2 has open input line by displaying the operation of the 1st comparator and it is detected that both the speakers 2 have open input line by displaying the operation of the 2nd comparator.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention provides a method for preventing damage when the input line of a speaker is disconnected.
This invention relates to a disconnection detection device for detecting L.

[Prior art]

Conventionally, there has been a device of this type as shown in FIG.

In FIG. 1, 1 is an amplifier, 2 is a speaker driven by this amplifier IKL, 3 is a sound collection microphone that collects sound from the speaker 2, and 4 is a device that detects the output sound pressure level of the sound collection microphone 3. This is the sound pressure level detection path N.

The output signal of the amplifier 1 is outputted to the speaker 2 as an audio signal. The sound collecting microphone 3 collects the audio signal '1' from the speaker 2 and converts it into a sound pressure level signal.

The sound pressure level detection circuit 4 detects the presence or absence of this sound pressure level signal, and determines that the input line of the speaker is disconnected when the sound pressure level signal is not detected. However, since the sound collecting microphone 3 collects not only the audio signal from the speaker 2 but also external noise and converts it into a sound pressure level, failure detection is inaccurate. If
It was difficult to determine whether only one machine had failed, or whether both machines had failed and there was a hole.

[Summary of the invention]

The present invention has been made to eliminate one of the drawbacks of the prior art described above, by using a disconnection detection circuit to detect the voltage level of the amplifier output.

It is an object of the present invention to provide a speaker input line disconnection detection device that can reliably detect a disconnection of a speaker input line.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A diagram illustrating an embodiment of the present invention will be described below. Second
In the figure, 1 is an amplifier, 2 is a speaker driven by the amplifier 1, and 6 is a disconnection detection circuit that detects the line voltage between the amplifier 1 and the speaker 2 to detect the presence or absence of a disconnection.

FIG. 3 shows an impedance equivalent circuit configured for the amplifier 1 and the speaker 2. The line impedance RL is very small compared to the line side impedance of speaker 2/,
The impedance r on the output side of is.

Eri for impedance matching with the line side impedance Rs of speaker 2.

becomes.

Assuming that the output voltage of amplifier 1 is E, the line voltage V is when there is no disconnection in the input line of speaker 20.

It is expressed in

Here, one point 5a172 of the input line of speaker 2:
If a disconnection occurs with one stroke of 5b, the line voltage V will be.

Then, '! 7? : If a disconnection occurs at both points 5a, L and 5b.

V=E...+41 becomes.

That is, the above formula +21, +31, +41'
a? As is clear from the comparison, the line voltage V changes between the case where both the input lines of the two speakers 2 are normal, the case where only one of the two speakers 2 is disconnected, and the case where one and both of the input lines are disconnected. There will be a difference in value.

In this invention, a disconnection detection circuit 6 is provided to detect a difference in line voltage depending on whether or not the speaker input line is disconnected. This disconnection detection circuit 6Fi.

and a first comparator which outputs an output when there are two or more speakers as shown in FIGS. 2 and 3.

a second comparator that provides an output when V=E;
It consists of a display device that operates in response to the outputs of these comparators. By displaying that only the first comparator has operated, it is notified that a break in the input line has occurred in one of the two speakers 2, and the second comparator is activated. In order to display something strange, the two speakers 2 are used to notify that the input line has been disconnected.

In the above embodiment, disconnection and detection were explained when two speakers were connected to one amplifier, but when only one speaker is connected to the amplifier, or when three or more speakers are connected Even if the speaker is connected, if a break occurs in the input line of the speaker, the line voltage will change, so it is important to compare this change with the normal voltage using a comparator to ensure that there is no break in the input line. can be detected.

〔Effect of the invention〕

In summary, according to the present invention, the line resistance of the speaker human-powered line is detected by the disconnection detection circuit.

Since this detected value is compared with a preset reference value, it is possible to reliably detect a break in the input line. In addition, when multiple speakers are connected to one amplifier, it is necessary to provide the same number of comparators as the number of speakers, and set the reference voltage of each comparator to a predetermined value. It can also be determined whether the input line of the speaker is disconnected.

Furthermore, since a sound collecting microphone is not required, the structure is simpler than the conventional one, and it can be constructed at a lower cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a conventional disconnection detection device. FIG. 2 is a block diagram showing a disconnection detection device according to an embodiment of the present invention, and FIG. 3 is an equivalent circuit diagram thereof. 1...Amplifier, 2...Speaker, 6...Disconnection detection circuit. Agent Masuo Oiwa Figure 1 Figure 2 Procedural amendment (voluntary) 1. Indication of the case Japanese Patent Application No. 58-202070 2. Name of the invention Speaker input line disconnection detection device 3. Representative of the person making the amendment Hitoshi Katayama Section 5, Column 6 of Detailed Description of the Invention of the Specification Subject to Amendment, Page 4, Line 3 of the Specification of Contents of the Amendment is amended. that's all

Claims (1)

[Claims] In a disconnection detection device that detects disconnection in the input line of a speaker connected to an amplifier, the line voltage of the input line is compared with a reference value corresponding to the line voltage of the input line during normal operation, and a difference is detected. A disconnection detection device for a speaker input line, characterized in that it is equipped with a disconnection detection circuit consisting of a comparator that outputs an output when the signal is detected, and a display device that operates in response to the output of the comparator.