Speaker grills
United States Patent [19] [H1 3,880,253  
 Kuhfus Apr. 29, 1975 SPEAKER GRILLS 791.142 9/i93s France .4 Nil/I75 829.445 3/:933 France Nil/I75 [75] Inventor: Gerd Kuhfus. London. Ontario.  
 Canada Primary E.ruminerStephen J. Tomsky l l Asslgneei Norther&#34; Electric p Almmey. Agent. or Firm-Sidney T. Jelly Limited, Montreal. Quebec. Canada 221 Filed: June 24. 1974 {57] ABSTRACT [21] Appl 482312 A speaker grill, particularly applicable to speaker-type telephone sets and similar items. is composed of a plu [52] U.S. Cl. l8l/l75 rality of closely spaced thin parallel ribs having a sinu- [51] Int. Cl. (110k 13/00; H()4 1/28 ous cross-section. for example somewhat Z-shaped. Field of Search l8l/l 75. 176. 155; 29/l60 with a mask attached to the near face of the grill An 29/1695 aperture is formed in the mask at the position of the speaker. When assembled to the telephone set it is not [56] References Cited possible to detect where the speaker aperture is. The UNITED STATES PATENTS ribs also create sinuous passages which prevent direct access to the speaker but permit passage of sound 2.214.393 9/1940 Wilbur .4 l8l/l75 from the speaker. FQRElGN PATENTS OR APPLICATIONS 57.x9x 3/1940 Denmark It&#39;ll/175 3 5 Drawmg figures PATENTEUAPmms $880,253  
 sum 2 or 2 v28 1 Fig. 4 W\\\\\\\\\\vw SPEAKER GRILLS This invention relates to speaker grills. particularly but not exclusively for telephone sets of the type in which a handset is not required. a speaker and a microphone being positioned in the telephone set.  
  A speaker grill has more than one function. While its primary function is to permit passage of sound from the speaker to the user. as it forms part of the casing or housing and can be seen. it necessarily has a cosmetic or design function. Ideally the grill should become part of the overall design of the article. not be obtrusive, and at the same time provide protection against items being pushed through the grill. Also. there is an added attraction where the grill extends over an area larger than the speaker if it is not possible to detect just where the speaker is situated.  
  The present invention provides a speaker grill comprised of a plurality of thin parallel ribs each having a particular cross-section. and with a mask secured to the inside of the grill, direct vision through the grill prevented by the mask at all positions except where the speaker is to be positioned. Assembly of the speaker to the grill seals off the unmasked portion of the grill and it is not possible to see through the grill.  
  The invention will be readily understood by the following description of one embodiment, as applied to a telephone set by way of example, in conjunction with the accompanying drawings in which:  
  FIG. 1 is a plan view of the outside of a cover showing a speaker grill;  
 FIG. 2 is a cross-section on the line II--II of FIG. 1;  
 FIG. 3 is a cross-section on the line III-III of FIG. 1;  
  FIG. 4 is a much enlarged cross-section of the grill in the area of circle A; and  
  FIG. 5 is a plan view of the inside of the cover of FIG. I.  
  As seen in FIG. I, the top cover or housing 10, for a telephone set which includes a speaker and microphone, has a grill 11 formed at one end. In the particular example this would be the top end. The grill is composed of a plurality of parallel ribs 12 extending in the direction of the longitudinal axis of the cover. As illustrated in FIG. 2 the top and bottom end flanges 13 and [4 of the cover are not perpendicular to the top surface or web 15 but are inclined outwardly. In the present example the rib formation. formed by the ribs 12, is carried partway down the top end flange 13. However. the ribs are not entirely separate for all the formation. This is seen in FIG. 2, where the ends of the gaps between ribs 12 are indicated at 16. The rib formation is carried over onto the end flange 13 for aesthetic reasons. Also seen in FIG. 2 is the mask [7.  
  FIG. 3 illustrates. in cross-section. the mask 17 in position in contact with the grill ll. Conveniently the mask is sonically welded to the ribs of the grill. This strengthens the ribs and prevents breakage. An aperture is provided in the mask, at a position occupied by the speaker when installed. The shape of the aperture seen at I8 in FIG. 5 and the periphery of the aperture I8 is indicated at 19 in FIGS. 2 and 3.  
  The ribs 12 are of a specific cross-section. This crosssection is intended to prevent direct access and sight in a direction normal to the top surface of the web 15 and also up to quite wide angles either side of the normal. The cross-section of the ribs is seen in more detail in FIG. 4. Two ribs I2 are illustrated in cross-section. in  
 FIG. 4. The cross-section is a modified Z form. having upper and lower cross-bars 21 and 22 respectively, joined by a short web 23, one cross-bar offset relative to the other. Each rib 12 is separated from the adjacent rib by a gap which essentially is composed of two channel portions 24 and 25, each extending substantially normal to the outer surface of the grill 11. The two channel portions are also offset relative to each other such that there is very little or no direct passage from front to back of the grill.  
  There is thus formed a sinuous passage and in the example the outer part -the portion 24 has substantially parallel walls 26, 27, while the inner part -portion 25 has walls 28, 29 which are inclined slightly to give a tapered section, the widest dimension at the inner face of the grill. In the example shown, one wall -28- is slightly more inclined than the other wall 29.  
  The two channel portions 24 and 25 unite along a line, indicated by dotted line 30 which extends from the wall 26 of portion 24 to wall 29 of the portion 25 and these are almost in a straight line in the example shown. Thus the two channel portions 24 and 25 are offset relative to each other as viewed in the cross-section of FIG. 4. This construction. of course, prevents direct sight or access. Walls 27 and 28 have arcuate portions respectively where they bend round to join the appropriate walls 29 and 26.  
  The widths of the channel portions 24. 25 and the amount of overlap to provide the gap or throat 31 are dependent on various parameters. Making the channel too narrow will restrict sound emission, while too wide a channel will permit foreign objects to be readily inserted and also will affect the appearance detrimentally.  
  Also illustrated in FIG. 4 is the positioning of the mask 17. As stated previously the mask 17 is conveniently sonic welded to the ribs I2. To facilitate the sonic welding. small ribs 32 extend along each rib 12. In the particular example the ribs 32 are triangular in cross-section coming to a thin edge which is in contact with the mask 17. The ribs 32 act as energy directors.  
  The mask 17 is preferably of dark material -black for example. Once the speaker is assembled to the cover 10, it is not possible to discern where the speaker is once the cover 10 is in position on the telephone set base. The grill looks exactly the same the whole width of the cover.  
  The mask and grill provide an extremely attractive appearance. The grill is strong and prevents easy access to the speaker from the outside of the telephone set such that the speaker might receive damage. The cover and grill is easily molded. If the mask I7 was to be dispersed with and the molding produced with the gaps between ribs extending right through the grill only where the speaker is to be positioned. either a more complex molding process would be necessary. or the position of the speaker would show.  
  Thus, for example. if the cover 10 is of white material, then if the gaps between ribs were to be produced only where the speaker is to be positioned. white material would be seen between the ribs. except at the speaker position. This would appear black between the ribs at this position. The same comment applies for other colours. except for black and perhaps other very dark colours. To avoid the colour showing between the ribs. a two-shot molding process could be used. Thus the grill could be formed with gaps between all the ribs.  
 as in the present example, and then the gaps, partially filled by a black material, for example by filling the channel portions at those parts of the grill where the speaker is not positioned. However this is expensive. time consuming and requires an extra mold. The use of the mask 17 avoids these difficulties. and also strengthens the ribs.  
  A speaker grill in accordance with the present invention is also suitable for various other forms of apparatus. in addition to telephone sets. For example speaker grills in accordance with the present invention can be used for radio sets and in other forms of communication apparatus.  
 What is claimed is:  
  l. A speaker grill in a housing comprising a plurality of parallel ribs in said housing and a mask secured to the ribs on an inner surface of the housing; and an aperture in the mask at a position to correspond with a speaker position; the ribs each having a cross-section, secured normal to the longitudinal axis of the rib, in the form of a modified Z shape and including upper and lower Crossbars connected by a web, the ribs separated by channels extending completely through the grill from the outside to the inside thereof, each channel of sinuous form, secured in cross-section normal to the longitudinal axis of the channel, and having outer and inner portions, the channel portions offset relative to each other to thereby substantially prevent direct view between the ribs in a direction normal to the outer sur face of the grill.  
  2. A speaker grill as claimed in claim 1, including narrow ribs extending along the inner surface of each lower crossbar, said mask in contact with said narrow ribs and sonically welded thereto.  
  3. A housing for a communication apparatus, includ ing a top cover, and a speaker grill in said top cover, said speaker grill positioned at an upper end of the cover and comprising a plurality of parallel ribs in said cover and a mask secured to the ribs on an inner surface of the cover; and an aperture in the mask at a position to correspond with the speaker position; the ribs each having a cross-section, secured normal to the longitudinal axis of the rib, in the form of a modified Z shape and including upper and lower crossbars connected by a web, the ribs separated by channels extending completely through the grill from the outside to the inside thereof, each channel of sinuous form, viewed in cross-section normal to the longitudinal axis of the channel, and having outer and inner portions, the chan&#39; nel portions offset relative to each other to thereby substantially prevent direct view between the ribs in a direction normal to the outer surface of the grill.