Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPS572798 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing one embodiment of a dynamic speaker according to the present invention, and FIGS. 2A and 2B are diagrams showing a method of connecting a thermistor of the speaker shown in FIG. 3 shows the input resistance of the loudspeaker according to the present invention, FIG. 4 shows the input / output characteristics of the dynamic loudspeaker according to the present invention in comparison with the conventional example, and FIG. And the relationship between the temperature of the voice coil and the direct current resistance. Explanation of symbols of main parts, 1 ························· Voice coil, 3 ········· Center piece, 4 ·······························・ ・ Thermistor. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic speaker having a voice coil such as a cone speaker and a horn speaker. Loudspeakers used in audio devices etc. need to have high fidelity when converting the waveform of the input signal to sound, and in particular the deterioration of the linearity when a large current input signal is supplied is small Is required. However, since approximately 90 of the power supplied to the voice coil of the speaker is released as heat, the characteristic deterioration due to the temperature rise of the voice coil is a problem. For example, due to temperature rise of voice coil 1-7? Because the resistance of the speaker increases and the decrease in sensitivity of the speaker and the occurrence of nonlinear distortion can not be avoided, in the case of the conventional speaker, the heat radiation effect of the magnetic circuit is enhanced and the heat resistance is improved. Since only measures for improvement are taken, when the resistance of the voice coil is increased, it is impossible to prevent the deterioration of the characteristics as described above. The present invention has been made to prevent the above-mentioned drawbacks of the conventional dynamic speaker, and provides a dynamic speaker capable of preventing the deterioration of the characteristics even when the temperature of the voice coil rises. The purpose is The dynamic speaker according to the present invention is characterized in that a negative temperature characteristic thermistor connected in series or in parallel to the voice coil 13-05-2019 1 is provided and arranged at a position near the voice coil such as a magnetic circuit. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an example in which the present invention is implemented in a cone speaker. In the figure, a voice coil 2 is provided at 2- to drive a speaker cone 1 and is disposed in a gap of a magnetic circuit composed of a center piece 3 and a yoke 4. Assuming that the temperature of the voice coil 2 is T, the value of T is expressed as a function of the input power W, and T = WRi α (represented by 1 (1 is a thermal resistance). Although α has a constant relationship, rapid thermal rise can not be avoided if thermal resistance or saturation occurs. The relationship between the input power W and the temperature T is shown in FIG. 4 by a solid line a, and similarly in FIG. 4 the relationship between the temperature T and the resistance R of the Heuss coil is shown by a broken line. As shown in this figure, the resistance R of the voice coil 2 is in proportion to the temperature T, but this can not be avoided because the wire forming the voice coil 2 has a temperature coefficient. The electrical characteristics of the voice coil 2 are as described above, but referring to FIG. 1 again, the thermistor 5 having a negative temperature characteristic is disposed on the center piece 3 of the magnetic circuit. Are thermally coupled. The thermistor 5 is further electrically connected to the voice coil 2, and the method of connection thereof is in series or parallel to the voice coil 2 as shown in FIG. 2 (A +, (B). It may be either. The thermistor 5 is characterized in that its resistance decreases as the temperature rises, and the combined resistance is kept almost constant against temperature change when connected to the voice coil 2 either in series or in parallel. It is possible. For example, FIG. 3 shows the relationship between the temperature and the resistance when the voice coil 2 and the thermistor 5 are connected in series, and the resistance value of the voice coil 2 and the resistance port of the thermistor 5 have temperature dependency, respectively. It is understood that the combined resistance value C is maintained at a substantially constant value while the C. is a dog. In FIG. 4, the solid line a and the broken line 6 respectively indicate the sound output level with respect to the input voltage of the speaker according to the conventional example and the present invention. It is clear from this figure that the dynamic speaker according to the present invention has excellent power linearity and less damping for large inputs. Furthermore, regardless of the magnitude of the input, a constant dynamic range is obtained, and the variation of the sound quality is small. Although the thermistor 5 is fixed to the center piece 3 of the magnetic circuit in the above embodiment, the present invention is not limited to the embodiment. The thermistor 5 may be disposed on the bobbin of the voice coil 2 or the like. In this case, in particular, the resistance value of the thermistor 5 immediately changes in response to the temperature change of the voice coil 2, so that the responsiveness is excellent, and the dynamic linearity of the speaker can be improved. 13-05-2019 2
© Copyright 2021 DropDoc