Cable strain relief apparatus

Abstract: Strain relief apparatus for relieving strain on a cable (28) of an electrical device having a housing (16) with a notched-out portion (17) therein includes a strain relief member (30) which is generally planar and is mounted directly into the notched-out portion (17). The strain relief member (30) has a straight channel (66) which has a U-shaped cross-section and which is dimensioned to provide an interference fit with the cable (28) after the cable (28) is mounted therein and which coacts with a wall (33) of the notched-out portion (17) to assist in retaining the cable (28) in the channel (56).

Description: This invention relates to strain relief apparatus of the kind for relieving strain on a cable of an electrical device. In the computer industry, it is important that a business machine, such as a printer, for example, be capable of being connected or interfaced to other electrical equipment. It is customary to connect the printer to other electrical equipment by using a cable. Typically, the cable would pass through an aperture in the housing of the printer and would then be connected to another business machine, such as a point of sale (POS) terminal. German Offenlegungsschrift No. DE-A-3 413 254 discloses a cover member for a cable entry aperture in an electrical device, which cover member is of a box-like shape and contains a meandering channel having protuberances therein to assist in retaining the cable in the meandering channel. Alternatively, instead of the protuberances, a diagonal retaining band may be used to assist in retaining the cable in the meandering channel. It is a somewhat cumbersome and awkward operation to locate the cable in the meandering channel. The document US-A-4 167 301 discloses a strain relief arrangement associated with a wall of a housing, the wall including a depressed region provided with a post and with a first slot communicating with the interior of the housing. A removable cover has fingers which engage holes located in the depressed region, the cover also having an aperature through which a screw can pass to engage with a threaded hole in the post. An abutment on the cover cooperates with the depressed region to define a second slot. A power cord passes through the first slot and extends through a right angled twist and bend prior to passing around the post and through a further right angled twist and bend to exit through the second slot. An external pull on the cord causes frictional forces to be established between the cord and the abutment, between the cord and the post, and between the cord and the first slot. It is an object of the present invention to provide strain relief apparatus of the kind specified, which facilitates easy mounting and removal of the cable in the strain relief apparatus. Therefore, according to the present invention, there is provided strain relief apparatus, for relieving strain on a cable of an electrical device, including an electrical device having a housing, and a strain relief member having a body which is generally planar, said body comprising a first body portion and a second body portion, and having mounting means secured to said second body portion for detachably mounting said strain relief member on said housing, characterized in that said body has a cable receiving means for receiving said cable and also for causing at least one bend in said cable, said cable receiving means including a channel which has a U-shaped cross-section dimensioned to provide an interference fit for said cable and which is secured to said first body portion so as to coact with said housing in order to facilitate retaining said cable in said channel when said strain relief member is mounted on said housing. One embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, in which:- Fig. 1 is a perspective view of a printer, showing how the printer can be mounted directly on top of a terminal; Fig. 1A is an enlarged view, showing a strain relief member included in Fig. 1 and also showing (in dashed outline) how the strain relief member is designed to facilitate introducing a U-shaped bend in the cable; Fig. 2 is another perspective view, showing how the printer can be remotely located from the terminal; Fig. 2A is an enlarged view, showing the strain relief member included in Fig. 1 having a frangible portion removed therefrom to provide an opening through which the cable can pass to a remotely located terminal and also showing (in dashed outline) the bends in the cable which result when the cable is routed therethrough; Fig. 3 is a view of a portion of' the printer, showing how the strain relief member is mounted in the printer housing; Figs. 4A and 4B are fragmentary views of the printer, showing the strain relief member in dismounted and mounted positions, respectively, and also showing how the strain relief member causes the cable to bend when the strain relief member is mounted in the printer housing; Fig. 5 is a view looking from the direction of arrow A of Fig. 3, showing first and second L-shaped mounting members having first and second projections, respectively, and also showing a cable receiving means; Fig. 6 is a cross-sectional view of the strain relief member, taken along the line 6-6 of Fig. 4A, showing the cable receiving means in the form of a generally U-shaped channel which is used to retain the cable in a mounted position in the strain relief member; Fig. 7 is a left side view of the strain relief member as viewed from Fig. 3; and Fig. 8 is a top view of the strain relief member as viewed from Fig. 3 showing the U-shaped channel and the first, second, third, and fourth projections used to secure the strain relief member to the housing. Fig. 1 is a perspective view of a printer 10. One function of the printer 10 is to print data 12 on receipt paper 14. The printer 10 comprises a housing 16 which can be mounted directly on top of a terminal 18 (Fig. 1). Alternatively, the printer 10 can be remotely positioned from the terminal 18, as is shown in Fig. 2. The printer 10 includes a cable 28 which operatively couples the electrical components (not shown) in printer 10 to the electrical components (not shown) in terminal 18. It is to be noted that a typical POS terminal 18 includes a keyboard 20 having a plurality of keys 22, a display 24, and a cash drawer 26. At the conclusion of a sales transaction, for example, one of the keys 22 may be actuated which causes the cash drawer 26 to open and also causes a total to be printed on the receipt paper 14 and displayed on the display 24. The housing 16 of printer 10 has a notched-out portion 17 which is best shown in Fig. 3. Notice that the notched-out portion 17 forms a top wall 33, and it also forms a first wall 32 in an opposed relationship with a second wall 34. The first and second walls 32 and 34 have therein first and second apertures 38 and 40, respectively. The first and second walls 32 and 34 also have therein first and second slots 42 and 44, respectively, as best shown in Fig. 3. The function of the first and second apertures 38 and 40 and the first and second slots 42 and 44 will be described later herein. As best shown in Figs. 4A and 4B, a strain relief member 30 made according to this invention is slid in the direction of arrow A in Fig. 4A into the notched-out portion 17 of the housing 16, as will be described hereinafter. In a preferred embodiment, the strain relief member 30 includes a planar member 36 having general top and bottom portions 46 and 48, respectively. A mounting means, which is comprised of first and second L-shaped mounting members 50a and 50b, is secured to the bottom portion 48 (Fig. 5) of the planar member 36 and is used to detachably mount the planar member 36 to the housing 16. The first and second L-shaped mounting members 50a and 50b project from opposed sides of the bottom portion 48 (Fig. 5) and are resiliently biased away from each other to facilitate mounting and dismounting the planar member 36 to and from the housing 16, as will be described later herein. In a preferred embodiment, the first and second L-shaped mounting members 50a and 50b each lie in planes that are generally perpendicular to the plane of the planar member 36, as shown in Fig. 5. As best shown in Fig. 4B, the first and second L-shaped mounting members 50a and 50b become operatively associated with the first and second opposed walls 32 and 34, respectively, when the strain relief member 30 is mounted in the housing 16. The first and second L-shaped mounting members 50a and 50b have first and second projections 52 and 54, respectively, extending therefrom. The first and second projections 52 and 54 have shapes which generally complement the shapes of the first and second apertures 38 and 40 (Fig. 3), respectively. The first and second projections 52 and 54 engage the first and second apertures 38 and 40 in the first and second walls 32 and 34, respectively, to retain the planar member 36 in a mounted position in the housing 16. As best shown in Figs. 4B and 5, the planar member 36 also includes third and fourth projections 56 and 58, respectively. The third and fourth projections 56 and 58 engage and coact with the first and second slots 42 and 44 (Fig. 3), respectively, to prevent the bottom portion 48 of the planar member 36 from pivoting away from the housing 16 when the planar member 36 is mounted thereto, as described below. The planar member 36 of the strain relief member 30 includes a cable receiving means 64 (Figs. 6, 7, and 8) for receiving the cable 28. In a preferred embodiment, the cable receiving means 64 is a straight, generally U-shaped in cross-section, channel 66 which is dimensioned to provide an interference fit with the cable 28 when the cable 28 is press-fitted therein. The channel 66 has a top edge 66a which becomes positioned in a predetermined relationship to the top wall 33 when the strain relief member 30 is mounted in the housing 16 such that the cable 28 cannot work its way out of the channel 66, as will be described later herein. As best shown in Fig. 1A, the cable 28 is threaded from the electrical components (not shown) in the printer 10 into the notched-out portion 17 towards the bottom portion 48 of the planar member 36. The cable 28 is threaded upwardly (as viewed in Fig. 1A), thereby causing a bend 28a therein and adjacent to the second L-shaped mounting member 50b. The cable 28 is then press-fitted into the cable receiving means 64 which causes another bend 28b in the cable 28. In a preferred embodiment, the cable 28 is threaded downwardly adjacent to the first L-shaped mounting member 50a causing a bend 28c therein (as best shown in Fig. 4B). The end of the cable 28 is then connected to the electrical components (not shown) in the terminal 18. Notice that this design of the cable receiving means 64 and first and second L-shaped mounting members 50a and 50b facilitates introducing a U-shaped bend in the cable 28 to further provide strain relief on the cable 28 in the event the cable 28 is jerked or pulled. The planar member 36 also includes a frangible portion 60 (Figs. 4B, 5, and 8) which is delineated by a line of weakness 62. The frangible portion 60 can be removed or broken away from the planar member 36 with a pair of pliers (not shown), for example, in order to provide an opening (Fig. 2A) through which a bend 28d in the cable 28 can pass from the printer 10 to the terminal 18 when the terminal 18 is located remotely from the printer 10. The operation and use of the strain relief member 30 will now be described. When it is desirable to relieve strain on the cable 28 of the printer 10, the cable 28 is bent and positioned in the straight, U-shaped cross-section, channel 66 as previously described. After the cable 28 has been positioned in strain relief member 30, the strain relief member 30 is positioned in front of and slightly below the notched-out portion 17 of the housing 16, as shown in Fig. 4A. The resilient first and second L-shaped mounting members 50a and 50b are manually biased towards each other while the top portion 46 of the planar member 36 is slid upwardly into the notched-out portion 17 in the direction of arrow A in Fig. 4A. As the planar member 36 is moved upwardly, the third and fourth projections 56 and 58 engage and coact with the first and second slots 42 and 44, respectively, prior to the first and second projections 52 and 54 being resiliently urged into the first and second apertures 38 and 40, respectively, to retain the strain relief member 30 in a mounted position in the housing 16. Notice that the third and fourth projections 56 and 58 engage and coact with the first and second slots 42 and 44 to prevent the bottom portion 48 of planar member 36 from pivoting away from the housing 16 after the cable receiving means 64 is mounted in the housing 16. In a preferred embodiment, the top edge 66a of the U-shaped cross-section channel 66 is positioned in an opposed relationship from the top wall 33 such that the cable 28 cannot work its way out of the U-shaped cross-section channel 66. The strain relief member 30 is removed from the housing 16 by manually biasing the first and second L-shaped mounting members 50a and 50b towards each other with a tool, like a bladed member, and sliding the strain relief member 30 downwardly (as viewed in Fig. 4A) out of the notched-out portion 17. In a preferred embodiment, the strain relief apparatus 30 is first mounted in the notched-out portion 17 of housing 16, and then the printer 10 is mounted on top of the terminal 18 (Fig. 1). If it is desirable to locate the terminal 18 remotely from the printer 10 (Fig. 2), then the procedure for mounting the strain relief member 30 in the housing 16 would be the same as described above, except that the cable 28 is routed to terminal 18 through the opening provided by the removed frangible portion 60, as best shown in Fig. 2A. In a preferred embodiment, a typical strain relief member 30 has a length of 86 millimetres (3.375 inches) and a height of 35 millimetres (1.375 inches). The planar member 36 and L-shaped mounting members 50a and 50b have typical thicknesses of 3.2 millimetres (0.125 inch), and the first, second, third, and fourth projections 52, 54, 56, and 58, respectively, have diameters of 6.3 millimetres (0.250 inch). The U-shaped channel 66 has a typical length of 60.3 millimetres (2.375 inches) and a typical internal dimension of 7.4 millimetres (0.290 inch), and the cable 28 has a typical diameter of 7.6 millimetres (0.300 inch). In a preferred embodiment, the strain relief member 30 is of a one piece construction which is molded from any suitable plastics material.

Claims: Strain relief apparatus, for relieving strain on a cable (28) of an electrical device (10), including an electrical device (10) having a housing (16), and a strain relief member (30), having a body (36) which is generally planar, said body comprising a first body portion (46) and a second body portion (48), and having mounting means (50a, 50b) secured to said second body portion (48) for detachably mounting said strain relief member (30) on said housing (16), characterized in that said body (36) has a cable receiving means (64) for receiving said cable (28) and also for causing at least one bend (28b, 28c) in said cable (28), said cable receiving means (64) including a channel (66) which has a U-shaped cross-section dimensioned to provide an interference fit for said cable (28) and which is secured to said first body portion (46) so as to coact with said housing (16) in order to facilitate retaining said cable (28) in said channel (66) when said strain relief member (30) is mounted on said housing (16). Strain relief apparatus according to claim 1, characterized in that said housing (16) includes a generally planar surface having a notched-out portion (17) therein, said notched-out portion (17) having first and second opposed walls (32,34) having first and second apertures (38,40) therein, and in that said mounting means includes said first and second L-shaped mounting members (50a, 50b) having first and second projecting members (52,54) respectively, cooperating with said first and second apertures (42,44) respectively, to retain said strain relief member (30) in a mounted position on said housing (16). Strain relief apparatus according to claim 2, characterized in that said first and second L-shaped mounting members (50a,50b) are resiliently biased away from each other to facilitate mounting and dismounting said strain relief member (30) on and from said housing (16). Strain relief apparatus according to claim 2 or claim 3, characterized in that said first and second opposed walls (32,34) have first and second slots (42,44) therein, respectively, said L-shaped mounting members (50a,50b) further including third and fourth projecting members (56,58) which are also secured to said second body portion (48) and which coact with and engage said first and second slots (42,44) respectively, in order to prevent the second body portion (48) from pivoting away from said housing (16) when said strain relief member (30) has been mounted thereon. Strain relief apparatus according to any one of claims 2 to 4, characterized in that said notched out portion (17) has a third wall (33) adapted to coact with said first body portion (46) to facilitate retaining said cable (28) in said channel (66) when said strain relief member (30) is mounted on said housing (16). Strain relief apparatus according to any one of the preceding claims, characterized in that said first body portion (46) includes a frangible portion (60) which can be removed from said body (36) to provide an aperture through which said cable (28) can pass to thereby provide a further bend (28d) in that said cable. Strain relief apparatus according to any one of the preceding claims, characterized in that said strain relief member (30) is of a one-piece construction and is made of a plastics material.

Inventors: WILSON HILLIS L, YAICHUK PETER W, WILSON, HILLIS L., YAICHUK, PETER W.
Applicants: NCR INT INC, NCR INTERNATIONAL INC.
Application year: 1990
Main classification: H05K5
IPC codes: H05K7, H05K5