JPS5871798A - Dynamic headphone - Google Patents

Abstract

PURPOSE:To improve the expansion of a low-pitched audio range by forming a diaphragm with a sheet of polyethylene terephthalate resin and setting the ratio between the thickness of the diaphragm and the diameter of the mobile part of the diaphragm within a prescribed range. CONSTITUTION:A frame 1 and a top plate 3 are made of a magnetic material, and the frame 1 doubles a magnetic circuit. A magnet 2 is magnetized in its depth direction. A magnetic gap 4 is formed between the outer circumference surface of the plate 3 and the inner circumference surface of the frame 1. The outer circumference edge of a diaphragm 5 is previously adhered to an edge ring 6, and this ring 6 is attached within the outer circumference edge 1a of the frame 1. As a result, the diaphragm 5 is set at a prescribed position of the frame 1, and at the same time a coil bobbin 7 is set within the gap 4. The diaphragm 5 is made of a sheet of polyethylene terephthalate resin so as to satisfy t/phi=4X10<-4>-5X10<-4>. In this case, (t) is the thickness of the diaphragm 5 and phi is the diameter of the mobile part of the diaphragm 5. The characteristics can be improved with 4.4X10<-4> in particular.

Description

[Detailed Description of the Invention] The present invention is characterized by 4! Regarding open-air headphones, the present invention aims to provide headphones that can reproduce rich bass, firm midrange, and extended high range by making them smaller.

Traditionally, headphones have tended to be compact, but when miniaturized in this way, the resonant frequency fo becomes high and the low frequency range becomes insufficient. Usually, a thick resin sheet is used as a diaphragm, but in such headphones, the resonant frequency fo is 200H.
z to 220 Hz, and cannot produce sufficient bass. In such a case, if the thickness of the sheet, that is, the diaphragm, is made thinner, the resonant frequency fO will be lowered and the above-mentioned purpose will be satisfied, but in this case, the high frequency range will not be produced and the overall sound will become weaker, resulting in the so-called The disadvantage is that the sound loses its tension. That is, the thickness of the diaphragm is t, the Young's modulus is E, and the stiffness is 8.
In this case, the stiffness S is 4 at 8-kE-, and when t becomes small, 8 becomes extremely small, and the resolution of sound deteriorates. Furthermore, it is a constant of proportionality.

In view of these points, the present invention has been developed to produce a signal that satisfies the bass range and provides a strong signal even in the treble range, even if the entire speaker is miniaturized, that is, even if the headphones in this example are made with a small diameter. These are small, Dynaelectric type headphones that can play music at a speed of 5.

The inventors of the present invention repeatedly conducted various experiments for this purpose, and found that there is a certain relationship between the structure of the diaphragm itself, the diameter of the flexible rod part of the diaphragm, its thickness, etc. be.

First, the unit of this type of headphone will be explained with reference to the drawings. (1) is a frame made of a magnetic material, that is, it also serves as a magnetic circuit. 121 is a magnet, which in this case is magnetized in the thickness direction. (3
) is a top plate, which is also made of a magnetic material, and forms a magnetic gap (4) between its outer peripheral surface and a portion of the frame il+ (a portion forming the inner peripheral surface).

(5) is a diaphragm, the outer periphery of which is an edge ring (
6), and by installing this snow ring (6) inside the outer edge (1a) of the frame (1), the diaphragm (5) is placed at the desired position of the frame (1). The coil bobbin (7) is disposed inside the magnetic FJ (43) described above. (8) is a voice coil.

With such a configuration, the present invention has problems with the diaphragm (
5) Polyethylene terephthalate resin (product name: Mylar, Lumirror, etc.), which is one of the polyester resins.
This diaphragm (5
) (in this example, the diameter of the vibrating part of the edge ring (6
) is the same as the inner diameter of ).

Data are shown for each example.

1st! 5th! 2711RII was busy, and the second
The table shows the resonant frequency fo and the value of D when the thickness t of the diaphragm is changed by f when fl=20M, and Table 3 shows the value of D when the thickness t of the diaphragm is changed by f when the thickness is 14.4 mm. Shang. is the diameter of the driver unit, and j+1 is the coil bobbin (
7) shows the diameter.

Table 1 Da = 27 ■ pO = 30m Table 2 Goo 20111 Da 0 = 23 ■ Table 3 Da = 14.4W #0 = 16 ■ The unit 5 in each table is 0.52. In addition, FIGS. 2 and 3 show the characteristics of Tables 1, 1, and 2, respectively, using the above-mentioned D as a parameter, with frequency on the horizontal axis and level on the vertical axis. However, X and 10 are omitted.

In the case of the unit shown in Table 1, D=3.3 (however, X 1
0-' is omitted. (hereinafter the same)), the fO is sufficiently low, but in this case, there is no so-called tension in the midrange and high range, resulting in a sound that is audibly lacking. Also, the unit with n=, s, j has fO of 210)-
I found that it was quite high pitched like the 1z, and the bass range was lacking in extension. p=4.4 for these
It was found that the fOl was sufficiently low, that is, the bass range was rich, and the midrange and treble ranges had a sufficiently smooth and firm tone, and were audibly good.

In the case of the units shown in Table 2, I)=4.
It was observed that the unit with D=3.0 had a rich bass range and very smooth midrange and high range, while the unit with D=3.0 had no so-called tension in the sound, and the unit with D=6 had a rich bass range. I felt like I was missing something.

In the case of the units shown in Table 3, those with D = 4.2 are preferable for auditory sense, and 1) -2, 8 lacks tension, and 1) = 5.5 lacks low frequency range. It turns out.

As a result of various other experiments, we found that although the diaphragm (5) was formed from a single sheet of polyethylene terephthalate resin, and thus the dynamic headphones were made smaller, and in this case, the size was still small. Regardless of the time, we have confirmed that it is possible to obtain an excellent unit that reproduces sound that has good extension in the bass range, is firm, and has good audibility.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a dynamic headphone to which the present invention can be applied, and FIGS. 2 and 8g3 are characteristic curve diagrams thereof, respectively. il+ is a frame, (21 is a magnet, and (5) is a diaphragm.

Claims (1)

[Claims] The diaphragm, which is a bobbin-shaped diaphragm for the voice coil placed in the magnetic circuit, is constructed from a single sheet made of polyethylene terephthalate resin material, with the diameter of the sheet at which it can vibrate as true, and its thickness as true. Dyna electric type headphones that are characterized by a variety of features.