HRP930019A2 - Completely linearly oscillating loud speaker planar membrane - Google Patents

Description

The technical field to which the invention belongs

The invention relates to the field of audio technology, that is, electro-acoustic converters - loudspeakers.

According to the International Patent Classification (IPC), the subject of the invention is classified, i.e. classified and marked with the classification symbol G10K 15/04.

Technical problem

The technical problem solved by this invention consists in the following: how to construct a planar membrane where the reaction deflection of the membrane itself will be exactly the same at all its points. The defined technical problem is solved by the proposed completely linearly oscillating planar speaker membrane.

State of the art

The most common type of speakers are electro-dynamic because their simplicity of construction, robustness and low price make them the most widespread. However, for high-quality sound reproduction, they have a disadvantage due to their non-linearity. Namely, the relationship between the actively driven part of the membrane and the passive part is largely on the side of the latter - passive, and as such is a source of large distortions (up to several tens of percent at low frequencies). The only way to effectively reduce distortion is for as much of the membrane as possible to be under the control of the driving force, i.e. to be active. This was realized with speakers of planar (flat) membranes, which can be divided into three basic groups:

a) electrostatic

b) with ribbon

c) magneto-planar.

With them, the ratio between the actively driven part of the membrane and the passive part is almost 100% in favor of the active one with electrostatics and tape systems and slightly less with magnetodynamic ones.

Attention should be limited to low frequencies where the amplitudes and distortions are the highest.

Due to the relatively small amplitude range in which the control of the driving force over the membrane is complete, the construction of membranes with large surfaces is resorted to.

The technique of forming a vibrating membrane is always the same: a plastic film-foil (usually polyester) is stretched and glued to a frame of certain dimensions (Fig. 1), which determines the lowest frequency (for given distortion). On the side view fig. 1, the membrane is taken from a state of rest for some desired amplitude which will only be realized in the very center of the membrane with a tendency to fall towards the edges (faster along the shorter x dimension) and equal to zero along the very edges. In the corners, the criticality is even greater when the membrane enters the antiphase (K-hatched).

Overall, such a potentially highly linear system is not, in fact, because the theoretical advantage of a planar membrane that is driven over its entire surface will only be realized when the reaction deflection of the membrane itself is completely equal in all its points.

With the above-mentioned, existing state of the art, it is not possible to realize this.

Description of the solution to the technical problem

The solution of completely linear deflection of the complete planar membrane is solved by the construction that is the subject of this patent application, and is shown in the following sketches:

- sketch 1 shows the known way of installing the membrane,

- sketch 2 shows a construction that enables equal deflection of the membrane in all its points,

- sketch 3 shows the method of mounting the membrane.

A frame 1 with a width of approx. 25-30 mm, on the entire inner edge of which is glued a silicone tube 2, the diameter of which is several millimeters and the thickness of the wall is determined by the required amplitude. In the corners 3, the tube is formed in a semicircle to maintain a constant mechanical resistance and prevent non-linear movement. Glue was applied along the entire length of the outer edges of the frame in area 4 with a width of approx. 5 mm (following the curvature of the studs).

The foil membrane 5, which has already been pre-tensioned on the second frame 6 (whose dimensions are slightly larger than frame 1), is mounted over the frame formed in this way, by gently pressing it down and gluing it to the outer edge with glue 7. The resulting situation can be seen on Figure 2 (side view).

The membrane thus formed is permanently and steadily stretched with a completely linear movement over the entire surface.

It has the following characteristics.

a) Constant tension regardless of the external temperature,

b) Absence of standing waves because there is no sudden transition from an elastic (membrane) to a rigid (frame) medium, i.e. reflection,

c) The criticality of the corners itself is completely eliminated by the linear operation of the membrane in that part as well,

d) The self-resonance of the membrane becomes effectively controlled because its stiffness is no longer necessary to be sacrificed in order to have the necessary elasticity as with a classically formed membrane,

e) Certain sound pressure (SPL-Sound Pressure Level) is now realized with a smaller amplitude and therefore smaller distortion, stronger efficiency, faster response of the membrane,

f) Formation of all forms of membranes including i

the ideal one - elliptical - is fully enabled,

g) the resulting sound is completely in phase.

In this way, the structural solution fully meets the required characteristics.

Statement on the best way for commercial use of the reported invention

To achieve the set basic goal - how to construct a planar membrane where the reaction deflection of the membrane itself will be exactly the same in all its points - it can be said that for the economic use of the invention in question, no special knowledge, experience and instructions are needed that should be applied. Only the knowledge that an average expert has in the subject area is necessary and sufficient for the successful application of the subject invention, and based on

of the given description of the invention.

Claims (2)

1. Fully linearly oscillating planar speaker membrane, indicated by the fact that a silicone tube (2) with a diameter of several millimeters and a wall thickness determined by the required amplitude is glued to the frame (1) with a width of approx. 25-30 mm, i.e. the entire inner edge in the corners (3), the pipe is formed in a semi-circle in order to maintain a constant mechanical resistance and prevent non-linear movement, and along the entire length of the outer edges of the frame in the area (4) with a width of approx. assembly of the foil membrane (5) is carried out. 2. Loudspeaker membrane according to claim 1, characterized by the fact that the frame (3) has bevels (8) in the corners.