JPS646635Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention relates to a speaker for a handset installed in a telephone handset, especially for cordless telephones where a large number of parts are packed inside the handset. ,
The present invention relates to a receiver speaker suitable for use in a device with a very small space for mounting the speaker.

(b) Prior Art Cordless telephone handsets have a large number of parts packed into the handset and require very little space to mount a speaker, and use ultra-compact speakers with a diameter of about 2 cm. FIG. 1 shows such a speaker. When a signal is supplied to the voice coil 1 of the speaker, the voice coil 1 and the bobbin 3 around which the voice coil 1 is wound are moved to the piston by the action of the magnetic circuit 2. Exercise. When the bobbin 3 makes a piston movement, the diaphragm 5 connected to the bobbin 3 and the frame 4 makes a piston movement and emits sound. However, this type of speaker is
As shown in the figure, since the speaker 8 is mounted inside the receiver 6 and used by placing it against the ear 7, the space in which the speaker 8 can emit sound is from the diaphragm 5 of the speaker 8 through the sound-transmitting hole 9 of the receiver 6. This is a minute space 11 up to the eardrum 10 of the ear 7, and this minute space 11 is connected to the receiver 6.
Since it is a closed space surrounded by the ear 7 and the ear 7, the diaphragm 5 is damped by the minute space 11. As a result, the characteristics of the speaker 8 became a narrow band frequency characteristic as shown by the solid line in FIG. 5, which was much worse than the frequency characteristic in free space shown by the broken line in FIG.

In order to solve these drawbacks, there is a system that expands the frequency band by providing an air chamber behind the diaphragm of the speaker and setting the resonant frequency of the air chamber near the high cutoff frequency of the speaker. However, because this type of speaker is large in size, it is not suitable for mounting in a handset like a cordless telephone, which is packed with parts and does not have a large space for the speaker. It was hot.

For this reason, there is a known speaker in which a window is provided on the back side of the frame 4 of the speaker shown in FIG. 1, so that the diaphragm 5 can be easily moved. In such a speaker, by setting the aperture area of the window to an appropriate area, the frequency band of the speaker can be expanded and the characteristics can be improved, so it is superior to that of a cordless telephone in terms of characteristics and size. It was suitable for use as a telephone receiver. but,
In order to optimize the aperture area of the window in order to improve the characteristics of the speaker, the area must be delicately adjusted. Adjustment was difficult.

(c) Purpose of the invention The present invention was developed in view of the above points, and aims to provide a speaker for a handset with excellent characteristics by modifying a conventionally used speaker.

(d) Structure of the invention The receiver speaker according to the invention includes a voice coil driven by an electric circuit, a bobbin around which the voice coil is wound, a diaphragm connected to the bobbin, and a speaker. It is composed of a frame that serves as an outer frame and has a plurality of windows, a ventilating material having breathability covering the windows of the frame, and a blocking material having no breathability joined on top of the ventilating material.

(E) Embodiment Figure 3 is a sectional view showing an embodiment of the present invention.
2 is a permanent magnet 13, center pole and bottom 14
and a magnetic circuit consisting of an upper plate 15, 1
6 is a voice coil arranged in the magnetic gap 17 of the magnetic circuit 12, 18 is a bobbin around which the voice coil 16 is wound, and 19 is the bobbin 18.
A diaphragm 20 connected to the upper plate 15 of the magnetic circuit 12 is fixed to the upper plate 15 of the magnetic circuit 12, and is connected to a plurality of windows 2.
1, a frame 22 elastically connects the diaphragm 19 to the frame 20;
9 is an elastic material integrally molded, 23 is a ventilation material that covers the window 21 of the frame 20, and 24 is a blocking material bonded on the ventilation material 23.

The ventilation material 23 is made of a low-density material such as nonwoven fabric or porous paper that has good air permeability. The shielding material 24 is made of a non-permeable, high-density material such as cardboard, plastic, or metal. The ventilation material 23 and the blocking material 24 made of such materials are both formed into a ring shape so as to cover the window 21 of the frame 20, and the ventilation material 23 and the blocking material 24 are adhered to the frame 20 in this order. be done.
Further, the window 21 has a shape as shown in FIG. 4, and serves as an air vent when the diaphragm 19 moves as a piston.

Now, when a signal is supplied to the boss coil 16,
Due to the action of the magnetic circuit 12, the voice coil 1
6. Bobbin 18 around which the voice coil 16 is wound
A diaphragm 19 connected to the bobbin 18 pistons back and forth to radiate sound forward. At the same time, the sound is also radiated to the rear, so the diaphragm 1
The pressure in the space surrounded by 9 and frame 20 increases. Then, the air in the space passes through the window 21 of the frame 20, passes through the ventilation material 23, and is discharged to the outside of the speaker.

Generally, it is known that when a window is provided on the back of a speaker and air is let in and out through the window, the acoustic impedance decreases at a frequency corresponding to the amount of air. It is known that the sound pressure of a speaker increases at frequencies where the acoustic impedance decreases. Therefore, if the ventilation amount of the ventilation material 23 is adjusted so that the acoustic impedance is the lowest at a frequency near the high cutoff frequency of the speaker, the sound pressure of the speaker will increase at that frequency, and the frequency band in the high frequency range will be increased. It can be enlarged, resulting in characteristics as shown by the solid line in FIG. Further, since the frequency at which the sound pressure of the speaker is desired to be increased can be changed only by changing the ventilation material 23, it is easy to set the frequency near the high cutoff frequency of the speaker. That is, when the amount of air flowing through the ventilation material 23 is large, the sound pressure of the speaker becomes high at a frequency lower than the high cutoff frequency, and when the amount of air is small, the sound pressure of the speaker becomes high. is a frequency higher than the above-mentioned high-frequency cut-off frequency, so if the material of the ventilation material 23 or the thickness of the ventilation material 23 is changed accordingly, appropriate frequency characteristics can be obtained.

Furthermore, by making small holes in the diaphragm 19 to make the diaphragm 19 easier to move, it is possible to expand the frequency band toward lower frequencies as shown by the broken line in FIG. 6, and the overall frequency characteristics are improved.

(f) Effects of the invention As described above, according to the invention, a speaker with good frequency characteristics can be provided by just slightly modifying a conventional speaker. Furthermore, since the frequency characteristics can be freely changed just by changing the ventilation material, it is possible to easily provide speakers with various frequency characteristics.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional receiver speaker, Fig. 2 is a sectional view showing its use, Fig. 3 is a sectional view showing an embodiment of the present invention, and Fig. 4 shows its frame. 5 is a characteristic diagram showing the sound pressure-frequency characteristic of the speaker of FIG. 1, and FIG. 6 is a characteristic diagram showing the sound pressure-frequency characteristic of the speaker of the present invention. Explanation of main drawing numbers, 20...Frame, 21...
Window, 23... ventilation material, 24... blocking material.

Claims (1)

[Scope of utility model registration request] A handset speaker mounted in a telephone handset, comprising: a frame having a plurality of windows; an air permeable ventilation material covering the windows of the frame;
A speaker for a handset, characterized in that a non-ventilating blocking material is provided on the ventilation material.