US1935869A - Gramophone - Google Patents

Description

Nov. 21, 1933. c. YOSHIZAWA GRAMOPHONE Filed Aug. 4. 1930 2 Sheets-Sheet 1 C .9 f. m

Nov. 21, 1933. c. YOSHIZAWA GRAMOPHONE Filed Aug. 4, 1930 2 Sheets-Sheet 2 WWW 03h I avvk 6 3 M/veA/ToQ -nnw Patented Nov. 21, 1933 UNITED STATES PATENT OFFICE 1 Claim.

My invention relates to improvements in gramophones characterized in the provision of a long and reversely curved sound channel or horn comprising partition walls vertically fixed between the top and bottom plates. The horn is made of plastic material such as gypsum, Portland-cement, hard rubber, celluloid, pulp, bituminous compounds, bakelite or any like plastic materials.

The object of the invention is to provide a gramophone producing a clear and undistorted sound closely similar to the original sound by avoiding harmful resonance and especially to reproduce low tone sounds distinctly and accurately.

In gramophones the sound to reproduced is much influenced by the length of the sound channel, or so-called horn arranged between the sound tube and the sound opening of the box. Gramophones provided with sound horn located outside the box may have a long sound way, but in gramophones not provided with trumpet it is difficult to provide a long and gradually widening sound channel within a lirn'ted box. The part of the horn is thereby forr ed straight or only slightly curved toward the opening, forming a short sound channel so that the low pitched sounds are apt to be weak and indistinct.

According to the present invention a horn having a curved or scrolled sound channel of enough length is formed by curved partition walls vertically fixed between the top and bottom plates. The manufacture of the horn is very simple and a sound tunnel of a rectangular section with the desired length and gradually broadening L s sectional area toward the outlet opening is obtained whereby a clear and unaffected sound may be reproduced.

It is also noted that in gramophones hitherto known the part of the sound channel or the horn being made of metal or wood the proper vibration of the horn itself aiiects the quality of the sound reproduced and the volume of the sound is changed from the original sound according to the nature of vibration and especially weakened for low pitched sounds. Whereas, according to the present invention the horn being made of plastic material comparatively free from vibration, the sound reproduced in the sound box is transmitted comparatively unchanged and the sound closely similar to the original sound may be reproduced. The plastic material may be moulded easily and being capable of increasing its thickness in proportion to the increase of the sectional areas the sound is further improved in this respect. The plastic material may be reenforced by suitable reenforcements.

The accompanying drawings show the improved gramophone embodying the present invention.

Fig. 1 is a vertical central sectional view of the gramophone.

Fig. 2 is a horizontal section thereof.

Fig. 3 is a cross sectional View of the horn removed.

Referring more particularly to the drawings the gramophone box (1) is provided at the lower side of its top plate with a casing (2) within which motor mechanism for driving the disk (3) is arranged. The sound box (4) is fixed at the end of the elbow tube (5), the other end of which is rotatably mounted on the sound tube (6) vertically leading into the box (1) as usual.

The curved horn (11), which forms the essential feature of my invention is formed by curved partition walls (10) vertically fixed between the top plate (8) and the bottom plate (9) One end of said channel is connected to the lower end of the vertical tube (6) and gradually increasing its sectional area toward the other end, opens at the outlet opening ('7) formed at the front side of the box (1).

The horn is made of plastic material such as gypsum, Portland-cement, hard rubber, celluloid, pulp, bituminous compounds, bakelite or any other similar materials. The top plate (8) and the bottom plate (9) of the horn are preferably made of said plastic materials, but they may also be made of Wood or metal in combination with the partition walls (10) of the plastic material.

The sound tube (6) is usually arranged at one side of the box (1) and for convenience in connecting said tube, the horn channel is preferably curved in one direction inwardly toward the centre and then from the centre outwardly to the opening (7) the channel is curved in the opposite direction, as shown in Fig. 2. To gradually increase the sectional areas of the sound channel the distance between adjacent partition walls (10) is gradually increased toward the outlet end of the horn when the top plate (8) and the bottom plate (9) are parallel, as shown in Fig. 3. In case the partition walls are fixed at equal distance from one another, the top plate may be stepped for each compartment in place of a single plate for increasing the sectional area of the sound channel, and a plane bottom plate (9) is fixed at the bottom. A portion of the top plate 8 is inclined as shown in Fig. 1 to increase both the width and the height of the sound channel. The thickness of the walls of the horn, the partition posite ends in a sound inlet and a sound outlet, said partitions being arranged in spaced relation to each other and reversely curved to provide a. sound channel vortically wound in one direction from the sound inlet to the centre of the horn and vortically Wound in the opposite direction from the center to the sound outlet of the horn, said channel being rectangular in section and gradually increasing in area from the sound inlet to the sound outlet.

CHUZABURO YOSHIZAWA.

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