US2272937A - Radio receiving apparatus - Google Patents

Description

Feb. 10, 1942. K, EMDE RADIO RECEIVING APPARATUS 2 Sheets-Sheet 1 Filed June 11, 1941 {M Karil'mde E 7 M Feb. 10, 1942. K. EMDE 2,272,937

RADIO RECEIVING APPARATUS Filed June 11, 1941 2 Sheets-Sheet 2 Patented Feb. 10, 1942 OFFICE RADIO RECEIVING APPARATUS Kurt Emde, Itasca, Ill., assignor to Zenith Radio a Corporation, Chicago, Ill.

Application June 11, 1941, Serial No. 397,609

1 Claim.-

This invention relates to radio receiving apparatus and more particularly to a radio receiving set including an arrangement of parts adapted to provide improved tone qualities and simplified easy tuning.

One of the principal objects of the invention is to provide a molded grill construction which will shield or conceal the parts behind it so that the need for the usual grill cloth, which is expensive and diflicult to apply, is eliminated.

Another object of the invention is to provide a grill construction which will improve to some extent the acoustic properties of a radio receiving set.

Another object of the invention is to provide a receiving set having a novel grill construction so associated with a loud speaker, indicator needle and dial that the set as a whole may be made more compactly.

Another object of the invention is to provide a cabinet for a broadcast receiving unit, including a chassis carrying a loud speaker, arranged so that the unit may be bodily inserted into the cabinet.

A further object of the invention is to provide comparatively simple drive means for simultaneously actuating a tuning condenser and a dial indicator.

Still another object of the invention is to provide a pilot light mounting means which will enable quick and easy assembly of the pilot light relative to the dial.

One of the principal features of the invention is a novel grill construction including louvers arranged concentric with the axis or center of the diaphragm of the loud speaker and with a dial and needle indicator interposed between the grill and the loud speaker, the axis of rotation of the needle indicator also being substantially concentric with the axis of the loud speaker. The grill, obviously, may be formed integral with the cabinet as shown herein, or the grill may be mounted upon the cabinet, or formed-and sold as a separate element for use with a loud speaker unit.

Another feature of the invention resides in a comparatively simple mounting means for a dial indicator needle, the mounting means including a plate preferably secured to the loud speaker and the chassis.

Other objects and features of the invention will be apparent from the following description taken in conjunction with the drawings in which:

Fig. l is a front elevation of a complete receiving set constructed in accordance with the principles of the present invention:

Fig. 2 is a view of the set with the major por-' tion of the front of the cabinet broken away;

Fig. 3 is an enlarged fragmentary sectional view taken on the line 3--3 of Fig. 1 and particularly showing the shape of the grill louvers and the construction of the supporting means for the indicator needle;

Fig. 4 is an enlarged fragmentary sectional view taken on the line @--4 of Fig. 2 and particularly showing the mounting means for the tuning shaft and the drive for the rotor shaft of the tuning condenser; and

Fig. 5 is a perspective view illustrating the details of the structure employed to enable quick and easy mounting of the pilot lights which serve as illuminating means for the dial.

Referring now to Figs. 1 and 2, the numeral i generally indicates a cabinet for the'receiver which may be made of Bakelite, molded plastic, or any other suitable material. The cabinet I is provided with a handle 2 whereby it may be readily carried from place to place. The handle 2 is secured to the cabinet l by suitable screws 3 mounted from the interior of said cabinet (see Fig. 2)

The broadcast receiving unit is generally indicated by the numeral [4 and includes a chassis 5 held in place within the cabinet by suitable screws 6 extended through the bottom I of said cabinet. Pads 8 depend from the bottom I of the cabinet and serve to space the cabinet proper from the surface of a table or other supporting means.

The front wall 9 of the cabinet I is provided with a circular opening l0 through which the shaft ll of a conventional on-and-oif and volume control switch l2 extends (see Fig. 2). A knob I3 is frictionally secured to the shaft ll to facilitate manipulation of the switch and control of the volume.

The front wall 9 is also provided with a circular opening M (Figs. 1 and 4) through which a main drive shaft l5 for actuating a tuning condenser It extends. A tuning knob I! is frictionally mounted upon one end of the drive shaft i5. The shaft l5 extends through an opening l8 in a front portion I 9 of the chassis 5. The end of the shaft I 5 opposite that carrying the knob l! is reduced in diameter as indicated at 20, thereby providing a shoulder at N. The reduced end 20 is received in an opening 22 formed in a bracket 23 which is welded or otherwise secured to the inner surface of the chassis portion It. The reduced portion 26 is provided with a circumferential groove 24 for the reception of a conventional split retaining washer 25. Thus, it will be apparent that the shaft I is free to rotate relatively to the chassis portion I! and the bracket 23 and is maintained in assembled relation with the bracket 23 by the shoul-- der 2! and the washer 25.

A vertical main plate 26 is provided with oilset tabs 21 (Fig. 2) secured to the chassis 5 by screws 26. A dial 23 having suitable indicia 36 to aid in tuning the receiver is secured to the main plate 26 by a plurality of eyelets 3|. The plate 26 is also provided at each of its upper corners with a circular opening 32 through which a pilot bulb 33 for illuminating the dial 2! extends. The opening 32 has diametrically opposed slots or notches 34 merging thereinto. The pilot bulb 33 is carried by a generally U-shaped mounting member 35 (see Figs. 3 and 5), said moimting member having laterally extending prongs 36 adapted to be received in the slots 34. The prongs 36 are angularly bent, as best shown at 31 in Fig. 5, and project beyond the extremities of the legs of said U-shaped member to provide shoulder portions 38. The mounting member 35 is preferably made of material having some springiness so that the sides of said member must be pressed toward each other to permit the prongs 36 to pass into the slots 34. Upon release of pressure upon the member 35, the prongs 36 automatically draw the shoulders 33 into tight engagement with the rear surface of the main plate 26 and thus provide a means for easily, quickly and securely mounting the pilot bulb 33 upon said main plate. As is clearly shown in Figs. 1 and 2, two pilot bulbs 33 are employed so that the dial 29 is amply illuminated. The upper corners of the dial 2!! are removed or cut away, as indicated at 39 (Fig. 2) so as not to interfere with the insertion of the pilot bulb 33 and prongs 36 into the opening 32 and notches or slots 34.

The main plate 26, in addition to being secured to the chassis 5 through the off-set tabs 21 and screws 23, is provided with a circular depression or recess 40 defined in part by a flange 4| (Figs. 2 and 3), which is secured to a conventional loud speaker 42 by circumferentially spaced screws 43. The chassis 5 is set back or recessed at 5 (Figs. 2 and 3) to accommodate the lower portion of the loud speaker 42 and enable the parts to be more compactly arranged.

Three radial arms 44 extend inwardly from the flange 4| of the plate 26 and each arm is off-set, as indicated at 45. The arms 44 merge with each other at a central hub portion 46 which is concentric with the center or axis of the speaker cone or diaphragm 41.

The central hub portion 46, as is best shown in Fig. 3, is provided with an aperture 48 adapted to receive one end of a stud shaft 49, a portion of said stud shaft being riveted over the metal of the hub portion to permanently secured the two together. A sheet metal pulley 50 is rotatably mounted upon the stud shaft 4! and includes a solid hub portion 5|, one end of which is reduced, as indicated at 52, to extend through a central opening 53 in the pulley 50 and an opening 54 in one end of an indicatorneedle 55. The reduced portion of the hub 5| is peened over the outer surface of the pulley 50 so that the hub 5i pulley 56 and indicator needle 55 are permanently assembled together in a desired predetermined relation. The stud shaft 43 is provided with a groove 56 adjacent its outer end for the reception of a conventional split washer 51. The washer 51 is adapted to retain the pulley 65 in asembled relation with the shaft 43. A felt washer 56 extends around the stud shaft 43 between the central boss portion 46 of the main plate 26 and the innermost portion of the hub 5| of the pulley II. The felt washer 54 may be saturated with lubricant, if desired.

The tuning condenser l6 (Figs: 2 and 4) is mounted upon the chassis 5 by suitable fastening means 6|. This condenser is of conventional construction and includes a rotor shaft 62 connected with rotor blades 63. A sheet metal pulley 64 has a bracket 65 secured to the rear side thereof by spot welding or otherwise. The bracket 65 is provided with an opening 66 to receive the rotor shaft 62 and the pulley 64 is provided with a similar opening 61. A set screw 63 threadedly mounted in the bracket 65 serves to secure the pulley 64 to the rotor shaft 62 in non-rotatable relation.

The pulley 64 (Fig. 4) is provided with a peripheral flange 63 having a generally V-shaped groove ll formed therein. The flange 69 is severed or broken and turned back, as indicated at H and 12, respectively, in Fig. 2. The drive shaft I5 is provided with a concave groove 13 intermediate its ends, as is best shown in Fig. 4. This groove is adapted to in effect serve as a drive pulley of comparatively small diameter. A flexible cable 14 of textile or other suitable material has at least one turn thereof wrapped around the drive shaft I5 in the groove 13 so as to provide suflicient friction to substantially preclude relative sliding movement of said cable with respect to said shaft when the tuning knob 11 is rotated. The cable 14 has eyelets l5 and I6 secured to its opposite ends. The cable 14 snugly engages with the bottom of the V-shaped groove II of the pulley 64 and is arranged so that the end portion thereof having the eyelet I5 extends over the bent flange portion H and the end portion having the eyelet 16 extends over the bent flange portion 12. One end of a spring II extends through both eyelets 15 and I6 and the opposite end of said spring is hooked around a pressed-out tongue I8 projecting from the body of the pulley 64. It will be apparent from the foregoing, that the spring 16 is arranged so as to provide continuous tension in the cable 14. With portions of the cable 14 extending over the bent portions II and 12, a more or less fixed relation is established between the cable 14 and pulley 64 so that rotary movement of the drive shaft l5. by turning of the tuning knob 11, will necessarily result in proportionate rotation of said pulley 64 and the rotor shaft 62 of the tuning condenser, to effect the desired tuning of the set.

The pulley SI associated with the indicator needle 55 has a peripheral flange I9 provided with a generally V-shaped groove 80. The flange I3 is broken and bent inwardly, as indicated at ti and 32 (Fig. 2), to provide portions similar to the bent portions II and 12 of the pulley 64. A second cable 83, preferably of material similar to that employed in the cable 14, is provided with eyelets 84 and 35 in the opposite ends thereof,

at 88 and 88. A pin 88 is fixed to the pulley 64 opposite the last-mentioned break in the flange 68. The cable 83 extends through the flange 88 and is wrapped around the pin 88 at least once so that the cable 83 is more or less fixedly secured in relation to the pulley 64. The cable 83 extends through openings 83 (Figs. 2 and 4) in the wall of the plate 28 defining the recess 48. Thus, it will be apparent that whenever the pulley 64 is rotated, corresponding rotation will be imparted to the pulley 58 to rotate the indicator needle 55 through substantially the same angle that the rotor 63 of the tuning condenser l6 has been turned.

The dial needle 55 is adapted to be rotated through a total angle of about 188 and it will be noted that the breaks in the flanges of the pulleys 58 and 64 are arranged so as to permit such movement without hindrance. Again, the dial 28 is of generous size and the portion I3 of the drive shaft l is small so that minute adjustment of the indicator needle 55 can be attained to simplify and facilitate the tuning operation.

The front wall portion 8 of the cabinet I is provided with a grill generally indicated by the numeral 8|. The grill 8| comprises a horizontal diametrical web 82 and two series of arcuate or concentric louvers 93 and 84, one series being arranged above and the other below the horizontal web 82. Thecross-sectional shape of the louvers 83 and 84 is best shown in Fig. 3, from which it will be noted that each of the louvers, in addition to being arcuate, extends on an angle of approximately 45 and terminates at its outer edge in a bead X. The louvers 83 are interconnected at their inner edge portions by vertically extending webs 85, and the louvers 84 are simi larly interconnected by web 86, The louvers 83 extend toward their axis exteriorly of the cabinet i and the louvers 84 extend toward their axis interiorly of said cabinet.

Although the louvers 83 and 84 are arranged concentrically, and may be said to be dished in opposite directions, the louvers 84 extend in the same angular direction as the louvers 83 so that the efiect of the louvers 83 will be to direct the sound waves from the speaker downwardly and toward a line passing through the axis of the speaker cone 41, whereas the tendency of the louvers 84 is to deflect the sound waves and spread the same in a direction away from the axis of the cone. In this manner a better distribution of the sound waves emitted by the loud speaker 42 is accomplished by deflection thereof downwardly, resulting in a better acoustical reproduction of the program being received.

It will also be apparent from Fig. 3 that the louvers 83 and 84 are arranged so that when the set is in its normal position, the plate 25, loud speaker 42, pulley 58, etc., are hidden from view, thereby eliminating the use of the usual grill cloth for this purpose.

The front of the cabinet I is rovided with a dial opening 81 defined in part by the outermost of the-louvers 83. The dial opening 87 is arranged so that the indicia 38 on the dial 28 are visible therethrough. The indicator needle 55 terminates in a more or less arrowhead-like end 88 that extends beyond the outermost louver 83 and cooperates with the indicia 38 to indicate the wave length to which the receiving setis tuned. A sheet of transparent material 88, such as Celluloid, extends across the dial opening 81 in front of the indicator needle 55 and is detachably secured in place by means of conventional push-type friction fastening elements 488. Th transparent sheet 88 is cut away behind the louvers 83, as indicated at l8l (Fig. 1), so as not From the foregoing description, it will be apparent that the receiver set may be placed into operation by turning the switch and volume control knob l3. It will also be apparent that the set may be tuned to the desired station by turning the tuning knob ll. Rotation of the knob ll, of course, turns the drive shaft l5, which drives the pulley 64 through the cable 14. The pulley 64 in turn drives the pulley 58 through the cable 83, so that the indicator needle traverses the dial 28. The set may be placed out of operation by turning the switch and volume control knob l3 back to its original position, in the-manner well understood. The dial 0r pilot lights 33 are positioned out of alignment with the dial opening 81 (Fig. 1) but furnish sumcient light to completely illuminate the dial and are preferably arranged in the circuit so that they are turned on whenever the knob l3 turns the switch i2 on.

It will be understood that various modifications and changes may be made in the structure herein disclosed without departing from the spirit of the invention or the scope of the ap-- pended claim.

I claim:

A grill for use in front of a radio loudspeaker, comprising: a plurality of concentric louvers, a web extending diametrically of said louvers so that a series of louvers is arranged upon opposite sides of said web, the louvers of each of said se-- ries being arranged upon an angle relative to their axis, the louvers of one series extending angularly toward said axis on one side of the Brill and the louvers of said other series extending angularly toward said axis on the opposite side of said grill. I

KURT EMDE.

Images