JPH0833087A - Speaker system - Google Patents

Abstract

PURPOSE:To realize a speaker system where the protection against the destruction due to the excessive input to a speaker unit is more exactly performed and reproducing sound is not interrupted also when a protective circuit operates. CONSTITUTION:A first overcurrent protective element 1 and a first resistance element 2 are connected in parallel. A second resistance element 3 is serially connected with these. The overcurrent protective circuit where a second overcurrent protective element 4 is connected with these serial/parallel circuits in parallel is serially connected with a speaker unit 5. When a large input is performed in short time, the second overcurrent protective element 4 which is smaller than the current set value of the first overcurrent protective element 1 becomes a large resistance first. The speaker unit 5 is driven through the overcurrent protective element 1 and the resistance element 3. Further, when the input becomes large, the resistance of the overcurrent protective element 1 becomes high and the speaker 5 is driven by the current limited through the resistances 3 and 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loudspeaker system used for a stereo device or the like and having a protection circuit against a large input.

[0002]

2. Description of the Related Art In recent years, as a power output of a power amplifier for driving a speaker system has been increased, there is a tendency that failures due to destruction of the speaker unit due to a large input increase. Hereinafter, an example of a speaker system having a conventional protection circuit will be described with reference to the drawings.

FIG. 2 is a block diagram of a speaker system having a conventional protection circuit. In FIG. 2, an overcurrent protection element 11 having a positive temperature coefficient is connected in series to an electrodynamic speaker unit 12, and an electric input from a power amplifier or the like is applied from an input terminal 13. When a large input of a predetermined level or more is applied to the input terminal 13 in this circuit, the overcurrent protection element 11 operates by the signal current flowing toward the speaker unit 12. That is, the overcurrent protection element 11 generates heat by applying a current equal to or more than a predetermined current, and has a positive temperature coefficient, so that the resistance value sharply rises and the input to the speaker unit 12 is cut off. This is to prevent burning of the speaker voice coil, which accounts for most of the failures in the electrodynamic speaker unit.

[0004]

However, since the overcurrent protection element used in the speaker system of the conventional example as described above is a type that detects the temperature rise of the element itself due to a large current as a sensor, an element having a fast response speed is There is a problem that the current output is small and the sound output is interrupted even when the speaker unit is normally destroyed and the signal is not destroyed. Further, an overcurrent protection element having a current capacity that does not destroy normal signal input to the speaker unit operates properly when a large input is applied for a relatively long time, but causes abnormal oscillation of the power amplifier. When an excessive input is applied for a relatively short time, the voice coil of the speaker unit rises in temperature faster and burns out. Further, in either case, there is a problem that the sound from the speaker system is cut off and the music or the like is interrupted.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to provide a speaker system in which the speaker unit is protected more normally and the reproduced sound is not interrupted.

[0006]

In order to achieve the above object, a speaker system according to the present invention comprises a first overcurrent protection element and a first resistance element connected in parallel, and a second overcurrent protection element is connected to the parallel circuit. A resistance element is connected in series, an overcurrent protection circuit in which a second overcurrent protection element is connected in parallel to the series-parallel circuit, and a speaker unit in which the protection circuit is connected in series between the input terminal and the overcurrent protection circuit. And a setting current value of the second overcurrent protection element is smaller than a setting current value of the first overcurrent protection element.

[0007]

The present invention has the above-described configuration, and when an excessive input is applied for a relatively short time such as abnormal oscillation of equipment, the second overcurrent protection element has a second current setting value smaller than that of the first overcurrent protection element. The resistance value of the current protection element increases first, the speaker unit is driven through the first overcurrent protection element and the second resistance element, and there is an excessive input for a relatively long time due to an abnormal music source. When applied, the resistance value of the first overcurrent protection element increases and the speaker is driven by the limited signal current through the second resistance element and the first resistance element, and is applied to the speaker unit at any stage. The signal current is limited and drops, but acts so as not to be interrupted.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of a speaker system having a protection circuit against excessive input according to an embodiment of the present invention. In FIG. 1, a first overcurrent protection element 1
Has a first resistance element 2 connected in parallel, a second resistance element 3 connected in series to the parallel circuit, and a second overcurrent protection element 4 connected in parallel to the series-parallel circuit. It forms a current protection circuit. The overcurrent protection circuit is connected between one of the input terminals 6a and one of the terminals 5a of the speaker 5, and the other terminal 5b of the speaker 5 is connected to the other terminal 6b of the input terminal 6. Are configured. In this configuration, the current capacity value (set current value) of the second overcurrent protection element 4 is smaller than the current capacity value (set current value) of the first overcurrent protection element 1, that is, a fast reaction is used. are doing.

The operation of the speaker system of the present invention constructed as above will be described below. First, in the operation when an excessive input is applied for a relatively short time such as abnormal oscillation of a device that could not be prevented by the protection circuit of the conventional example, the second overcurrent protection element 4 having a fast reaction works first, Since the resistance of the second overcurrent protection element 4 becomes high and almost no current flows through the overcurrent protection element 4, the speaker unit 5 is connected to the input terminal through the second resistance element 3 and the first overcurrent protection element 1. The electric signal applied to 6 flows. In this case, the current is limited by the second resistance element 3, and the destruction of the speaker unit 5 mainly due to the burning of the voice coil can be prevented. At this time, the reproduction level of the acoustic reproduction sound from the speaker unit 5 is reduced, but is not interrupted.

Further, when an excessive input for a relatively long time due to an abnormal music source is applied to the input terminal 6, the overcurrent protection element 1 also operates and the resistance value of the overcurrent protection element 1 becomes high. Then, since the signal current flows to the speaker unit 5 through the second resistance element 3 and the first resistance element 2, the signal current is further limited and the speaker unit 5 is protected from being destroyed. Even in this case, the sound reproduction output from the speaker unit 5 is further cut off, but is not cut off.

As described above, according to the present embodiment, if the values of the overcurrent protection elements 1 and 4 and the resistance elements 2 and 3 are properly selected, the speaker unit 5 is protected from being destroyed and even when an excessive input is applied. The speaker playback output sound is not interrupted. Further, when the excessive input as described above is eliminated, the original state is automatically restored and the normal reproducing operation can be performed.

[0012]

As described above, in the speaker system of the present invention, the first overcurrent protection element and the first resistance element are connected in parallel, and the second resistance element is connected in series to this parallel circuit. Then, the overcurrent protection circuit in which the second overcurrent protection element is connected in parallel to this series-parallel circuit is connected in series to the speaker unit, and the set current value of the second overcurrent protection element is the first overcurrent protection element. By making the current smaller than the set current value of the protection element, when an excessive input is applied for a relatively short time such as abnormal oscillation of equipment, the second overcurrent protection element first becomes large in resistance and the first overcurrent protection element becomes If the speaker unit is driven through the overcurrent protection element and the second resistance element, and if an excessive input for a relatively long time due to an abnormal music source is applied, the resistance of the first overcurrent protection element becomes high. Nari second resistance element and Since the drive is a speaker in a restricted signal current through the resistor element, it is not also reproduced sound when the protection circuit operation is interrupted to protect the speaker unit from being destroyed by a large input.

[Brief description of drawings]

FIG. 1 is a block diagram of a speaker system according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional speaker system.

[Explanation of symbols]

 1 1st overcurrent protection element 2 1st resistance element 3 2nd resistance element 4 2nd overcurrent protection element 5 Speaker unit 6 Input terminal

Claims (1)

[Claims] 1. A first overcurrent protection element and a first resistance element are connected in parallel, a second resistance element is connected in series to this parallel circuit, and a second overcurrent is connected to this series-parallel circuit. An overcurrent protection circuit in which a protection element is connected in parallel, and a speaker unit in which the protection circuit is connected in series between an input terminal, the set current value of the second overcurrent protection element is the first A speaker system characterized in that it is smaller than a set current value of one overcurrent protection element.