US2174128A

US2174128A - Loudspeaker

Info

Publication number: US2174128A
Application number: US185110A
Authority: US
Inventors: Jyrch Herbert
Original assignee: Individual
Current assignee: Individual
Priority date: 1936-11-25
Filing date: 1938-01-15
Publication date: 1939-09-26
Anticipated expiration: 1956-09-26
Also published as: BE424804A; FR829844A; GB487576A

Description

Sept. 26, 1939. H. JYRCH LOUDSPEAKER Filed Jan. 15, 1938 Patentedsepti 26,

UNITED STATES PATENT OFFICE Application In 4 Claims.

This invention relates to a loud-speaker for loud-speaker installations on railway platforms etc. It has for its object to reduce as much as possible the transmission of sound to neighbour- 5 ing platforms, thus directing the sound towards the platform itself, and this is attained by the fitting of the loud-speaker to the back of a tubular member open towards the front, which is somewhat inclined to the horizontal so that the desired directive effect is attained. It is further improved by the provision of a broad slot in this tubular member on its underside. Preferably, downwardly bent guide surfaces are fitted, e. g. attached to the edges of the slots.

In this manner the low speech frequencies, which are not capable of being confined, immediately balance themselves out downwards I through the slot provided and can, as in effect, be short-circuited. Experiments have shown that in this way considerably better clarity and directional characteristics result. A further advantage of this method is to be seen in the fact that there is also good clear distribution in the region of the platform directly under the loud-speaker. There is very little side sound spreading, because the slot directs the sound through the guide surfaces there provided. In the case of long platforms it is an advantage to install several loud-speakers at about 20 metres apart. For this purpose the electro-mechanical part, e. g. a cone reproducer, is arranged in the center of a tubular member, which preferably consists of two casing sections extending to opposite sides oflthe cone.

a different inclination, i. e., the rear part a steeper inclination than the front part, so that one section transmits about one-third and the other about, two-thirds of the entire length of the transmitting range. If two such loud-' speakers are arranged at a distance apart of about 20 metres, the rear part of the casing having the steeper inclination is so .directed that the sound fades out at about one-third of the distance from the casingconstituting the front part of the next loud-speaker, whereas the said front part of the neighbouring loudspeaker covers two-thirds of this distance. It follows therefrom as an advantage of. an essential part of the inventive idea, viz.,the inclination of both parts. that the transmitting beams of the tubular member do not traverse the line connecting the two loud-speakers, thus the clarity of the installation is much improved.

Embodiment of the invention is illustrated in the drawing, in which It is advantageous to give both parts of the'casing January 15, 1938, Serial No. 185,110 "Germany November 25, 1936 Fig. 1 shows the loud-speaker from the side,

Fig. 2 from below.

Here the loud-speaker is so constructed that it transmits the sounds to both ends. Two tubular members, I and 2, having the flanges F and F support the flange 3 of the membrane or diaphragm of the loud speaker. That is to say, the flanges F and F clamp the membrane or a part thereof between the same and suitable bolts B may be used for connecting the flanges F and F in the conventional manner. The said tubular members I and 2 are obliquely cut at I a and 2a and are provided in their lower part with a slot lb, 2b respectively. These slots are bounded laterally by a guide surface lo and 2c respectively.

As shown in Fig. l, the inclination of the tubular member 2 to the horizontal is greater than the inclination of the tubular member I. This degree of inclination depends on the distance from each other of two loud-speakers. The inclination is preferably so chosen that the part 2 has a range of one-third and the part I twothirds of the complete length of the transmitting range. Practical experiments with such meas;- urement have given extraordinarily good clarity and the smallest possible lateral transmission towards the neighbouring platform.

From the foregoing it will be apparent, that the present invention relates to a loud-speaker of the public address type, which has particular adaptability to use in connection with the loading platforms in railway stations. In a situation of this kind it is desirable to have the announcement heard on a particular platform in such a way, that it cannot be distinctly heard on an opposing platform, so that passengers cannot become confused. To that end it is proposed to support or suspend a number of units constructed in accordance with the present invention at predetermined intervals along the platform in such a way, that speech sounds emanating from the series of loud-speakers will be heard distinctly along the line of the platform. To obtain this result, it is desired, as previously set forth, to downwardly incline the opposite tubular sections of the loud-speakers, so that the sounds emanating from one will not conflict substantially with sounds emanating from the other. It will be apparent, that the degree of inclination will be varied according to the spacing of the loudspeakers along the platform, as, for example, according to the illustration previously given.

I claim:

.1. A sounddirecting construction for loudspeakers of the public "address type, including in combination, an electro-mechanical sound reproducingunit, and a pair of oppositely extending downwardly inclined tubular casings, located one at each side of said imit, said casings being of substantially uniform diameter throughout and npen at their outer ends, the bottom portion of each casing being provided with a slot extending inwardly from its open end to permit 10w speech frequencies to escape downwardly before reaching the said open end.

2. A device as set forth in claim 1, wherein one casing is of shorter length than the other, said casing of shorter length having a greater down ward inclination than said other sections thereby to provide a diiferential sound transmitting range between the casings.

3. A device as set forth in claim 1, wherein the slot in each casing is provided at opposite sides thereof with sound directing flanges.

4. A sound directing construction for loudspeakers of the public address type particularly adapted to be supported above a railway station platform, including in combination, an electromechanical sound reproducing unit and tubular casing sections located one at each side of said unit, said sections being inclined downwardly from the unit toward the platform and each having a slot at its bottom side.

HERBERT JYRCH.