US3693752A

US3693752A - Loud speaker system

Info

Publication number: US3693752A
Application number: US184404A
Authority: US
Inventors: Shouzo Kinoshita; Isao Yamamura
Original assignee: Pioneer Electronic Corp
Current assignee: Pioneer Corp
Priority date: 1970-09-29
Filing date: 1971-09-28
Publication date: 1972-09-26
Anticipated expiration: 1989-09-26
Also published as: DE2148466C3; DE2148466A1; DE2148466B2

Abstract

A loud speaker is installed on the rear plane of a baffle board facing an opening within the baffle board which opening in cross section takes the form of a narrow forwardly directed cone and an annular acoustic resistance member which is triangular shaped in section is fixed to the cutting plane of the opening. Alternatively, a ring member which narrows in a forward direction to form a forwardly narrowing cone in cross section is fixed to the front of a loud speaker flange and fits within a baffle board opening with the flange installed on the rear plane of the baffle board. An annular acoustic resistance member of triangular cross section is fixed to the inside surface of the forwardly narrowing ring or to the front surface of the loud speaker flange internally of the ring.

Description

United States Patent '1 I Kinoshita et ,1.

[54] LOUD SPEAKER SYSTEM [72 Inventors: Shouzo Kinoshita, Tokorozawa; lsao Yamamura, Tokyo, both of Japan [731 Assignee: Pioneer Electronic Corporation, To-

kyo,.lap'an [22] Filed: Sept. 28, 1971 {21] Appl.No.: 184,404

[30] Foreign Application Priority Data 51 Sept. 26, 1972 3,067,834 l2/l962 May 18l/31B Primary Examiner-Stephen J. Tomsky Att0rney-Sughrue, Rothwell, Mion, Zinn & Macpeak 5 7 ABSTRACT A loud speaker is installed on the rear plane of a baffle board facing an opening within the baffle board which opening in cross section takes the form of a narrow forwardly directed cone and an annular acoustic resistance member which is triangular shaped in section is fixed to the cutting plane of the opening. Alternatively, a ring member which narrows in a forward direction to form a forwardly narrowing cone in cross section is fixed to the front of a loud speaker flange Y and fits within a baffle board opening with the flange installed on-the rear plane of the baffle board. An annular acoustic resistance member of triangular cross section is fixed to the inside surface of the forwardly narrowing ring or to the front surface of the loud speaker flange internally of the ring.

6 Claims, 4 Drawing Figures LOUD SPEAKER SYSTEM BACKGROUND OF THE INVENTION th e same protrudes forwardlyof the loud speaker installing flanges.

2. Description of the Prior Art When dome-type loud speakers, or similar loud speakers whose front part protrudes forwardly of the installing flanges, are installed within a loud speaker enclosure, if the speaker is installed on the front plane of a baffle board of the loud speaker enclosure, it is impossible to properly decorate the same by means of a saran net panel by stretching the netacross-"the baffle board due to the protruding portion of the loud speaker. On the contrary, as' shown in FIGS. 2A and 2B, loud speakers .of this type may be readily installed onthe rear of the baffle board with the protruding portion projecting within an opening formed within the baffle board. However, if the opening of the illustratedbaffle board 1 is cut such that the walls defining the opening are at right angles to the plane of the board, the acoustic characteristics of the loud speaker system are adversely affected by cavity phenomena and reflection phenomena which occur in the opening. Even where the opening is in the shape of a cone which widens in the forward direction as shown in FIG. 2B, interference between emitted sound and reflected sound cannot be avoided.

SUMMARY OF THE INVENTION The present invention takes notice of the afore-mentioned problems. It is one object of the present invention to provide a loud speaker system with means for reducing the influence of cavity phenomena andreflection phenomena occurring within an opening of a baffle board and thereby improving the acoustic characteristics of a loud speaker system.

It is another object of the-present invention to provide' a loud speaker system in which the opening of the baffle boardis in the form, in cross section, of a narrowing cone in a forward direction and wherein an annular acoustic resistance member of triangular shape in cross section and being formed of sponge or rubber, is fixed to the cutting plane of the opening.

It is a further object of the present invention to provide a loud speaker system in which a ring member narrows in a forward direction to form, in cross section, a

forwardly'narrowing cone and is arranged on the flange of the loud speaker permitting the loud speaker to be fixed in position within an opening of a baffle board, with an annular acoustic resistance member, shaped triangularly in cross section and formed of sponge or rubber material, being fixed either to the inside surface of the ring member or to the flange just inside the ring member.

Other objects, advantages and features of the present invention will become apparent from the following description taken. in conjunction with the accompanying drawings. 1

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A and 1B are principal, sectional views of two embodiments of loud speaker systems in accordance with the present invention.

FIGS. 2A and 2B are principal, sectional views of two prior art loud speaker systems.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1A illustrates one embodiment of this invention. A baffle board 3 is provided with a circular opening 31 which is so shaped as to define a forwardly narrowing cone. An acoustic resistance 4 which is annular in form, is of triangular shape in cross section and may be formed of sponge or rubber material with the acoustic resistance member 4 being fixed to the baffle board on the cutting plane 31A. A middle or high range loud speaker 5 such as a dome type loud speaker is installed on the baffle board 3 with'screws 6,.such that the dome projects within the opening 31'. Alternatively, a multi-cellular horn type loud speaker may be installed therein.

Consequently, a portion of the sound emitted fro the loud speaker 5 is reflected first by the cutting plane 31A of the baffle board 3 andsecondly by flange 51 of the loud speaker 5 passing through the acoustic resistance member 4 and the reflected sound is then emitted outwardly. Since the reflected sound is sufficiently reduced by the capacity through the acoustic resistance member 4, the direct sound emitted from the loud speaker 5 through the opening and the reflected sound would not substantially interfere with each other. Further, because of the buffer effect of the acoustic resistance member 4, a cavity phenomena occurs in the opening 31 which scarcely disturbs the acoustic characteristics of the speaker system.

Moreover, since the opening 31. is conical in shape, a standing wave train is hardly set up within this opening.

FIG. 1B shows another embodiment of this invention. The same elements shown in this Figures, as shown in FIG. 1A, carry the same numerical designations. In the loud speaker system illustrated in FIG. 18, a solid ring member 7 tapers inwardly in a forward direction to define a narrow cone in cross section, and is arranged on the flange 51 of the loud speaker 5 and operates in the same manner as the cutting plane of the baffle board 3 of the first embodiment which also narrows in a conical forward manner. An acoustic resistance member 4 is fixed to the inside surface of ring member 6 in similar fashion to the previous embodiment. Alternatively, the resistance member 4 may be fixed to the flange 51 internally of the ring member 6.

What is claimed is:

1. In a loud speaker system comprising a baffle board having an opening therein and a loud speaker installed on the rear surface of the board and spanning said opening, the improvement wherein:

loud speaker to absorb soundsreflected from said 7 plane.

2. The loud speaker system as claimed in claim 1, wherein said opening is defined by a cutting plane within said baffle board inclined inwardly in the direction of emitted sound and said hollow acoustic resistance member lines said cutting plane and faces said loud speaker.

3. The loud speaker system as claimed in claim 2, wherein said acoustic resistance member is triangular shaped in cross section.

4. The loud speaker system as claimed in claim 3, wherein said opening is circular, and said hollow acoustic resistance member is annular.

5. The loud speaker system as claimed in claim 1, wherein said reflecting plane is formed by a ring member narrowing in the direction of emitted sound, said loud speaker ismounted to said baffle board by a flange, said ring member is fixed to the front surface of said flange within said opening, and said acoustic resistance member is fixed to the insidesurface of said ring member. 7

6. The loud speaker system as claimed in claim 1, wherein said loud speaker is installed on the rear surface of said baffle board by a-flange member, a ring member is positioned within said opening and tapers inwardly in the direction of emitted sound, is fixed to the flange member on the front surface of the same, and an acoustic resistance member is annular in form, triangular shaped in cross section and is fixed to the surface of one of said members and positioned between the inside surface of said ring member and the front surface of said flange member.

i I i

Claims

1. In a loud speaker system comprising a baffle board having an opening therein and a loud speaker installed on the rear surface of the board and spanning said opening, the improvement wherein: said opening includes means defining a sound reflecting plane inclined inwardly in the direction of emitted sound, and wherein a hollow acoustic resistance member lines said plane and faces said loud speaker to absorb sounds reflected from said plane.

5. The loud speaker system as claimed in claim 1, wherein said reflecting plane is formed by a ring member narrowing in the direction of emitted sound, said loud speaker is mounted to said baffle board by a flange, said ring member is fixed to the front surface of said flange within said opening, and said acoustic resistance member is fixed to the inside surface of said ring member.

6. The loud speaker system as claimed in claim 1, wherein said loud speaker is installed on the rear surface of said baffle board by a flange member, a ring member is positioned within said opening and tapers inwardly in the direction of emitted sound, is fixed to the flange member on the front surface of the same, and an acoustic resistance member is annular in form, triangular shaped in cross section and is fixed to the surface of one of said members and positioned between the inside surface of said ring member and the front surface of said flange member.