Abstract:
A lock structure especially useful for locking a cabinet cover to a bottom plate makes it possible to integrate and separate the cabinet cover and the bottom plate quite easily, and also secures the cabinet cover and the bottom plate quite tightly to prevent any play between the two.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a lock structure for integrating a cabinet cover and a bottom plate together. 
     A cabinet accommodating therein electric/electronic components such as a printed circuit board generally consists of a cabinet cover and a bottom plate that are separably molded, and push buttons, switches and the like are fitted to the surface of the cabinet cover. Manipulation of these push buttons and switches applies a desired signal or instruction to the electric circuit portion. In such a cabinet, the following requirements (1) through (4) must be satisfied. 
     (1) The cabinet and the bottom cover should be integrated together easily. 
     (2) No play should occur after they are integrated. 
     (3) Separation between the cabinet cover and the bottom plate should be made easily. 
     (4) The structure should be simple. 
     However, none of the conventional lock structures have succeeded in perfectly satisfying all of these requirements. Most of them involve the drawback that the integration is easy, by separation is difficult, or vice versa, for example. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a lock structure which is simple in construction, is capable of easily integrating and separating the cabinet cover and the bottom plate and eliminates play once the cabinet cover and the bottom plate are integrated. 
     Another object of the present invention is to provide a lock structure which can be produced economically on a mass basis by plastic molding. 
     According to the invention, mating structures are provided for resiliently holding the cabinet together, and rod-like structures projections are also provided for easing separation of these. 
     These and other objects, as well as advantageous features, of the invention will become clear from the following description of the invention taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a cabinet to which the lock structure in accordance with the present invention can be applied; 
     FIG. 2 is a perspective view of the interior of the cabinet cover; 
     FIG. 3 is a perspective view of the interior of the bottom plate; 
     FIG. 4 is a sectional view of the cabinet at the time of lock (or, when it is integrated); 
     FIG. 5 is a schematic view useful for explaining the locking of the cabinet cover and the bottom plate; and 
     FIG. 6 is a schematic view useful for explaining the separation of the cabinet cover and the bottom plate. 
     In these drawings portions associated with the lock are illustrated but other members and components such as switches and push buttons to be fitted to the cabinet or other electric/electronic components are not shown. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, reference numeral 1 represents a plastic cabinet for accommodating therein a tuner for VHF and UHF channels in a television receiver and reference numeral 2 represents a cabinet cover equipped with apertures 2a, 2b, . . . and 2l for the insertion of channel selection push buttons, and with an aperture 2m for the insertion of a band selecting switch. Reference numeral 3 represents a bottom plate. The cabinet cover 2 and the bottom plate 3 are shaped in a box-like form and when integrated together, they define a hollow space between them for accommodating electric/electronic components such as a printed circuit board. 
     In FIG. 2, reference numerals 21, 22 and 23 represent latch members each having a sheet-like form and resiliency. These latch members have rectangular anchor holes 21a, 22a and 23a formed in the upper central portions, respectively, and are integrally provided on the ceiling portion 20b of the cabinet cover 2 in such a fashion that gaps 21b, 22b and 23b about 2 mm wide are present with respect to the frame side wall 20a of the cabinet cover 2, respectively (see FIG. 4). Reference numerals 24 and 25 represent anchor protuberances that are integrally provided to the ceiling portion 20b, and are adapted to engage with cylindrical anchor portions on the bottom plate 3, which anchor portions will be described later, and tightly fix the cabinet cover 2 to the bottom plate 3. All of the cabinet cover 2, latch members 21-23 and anchor protuberances 24 and 25 are integrally molded by molding a plastic inside molding die. 
     In FIG. 3, reference numerals 31, 32 and 33 represent anchor pawls that are provided on the frame side wall 30a of the bottom plate 3 and have hook-like protuberances 31a, 32a and 33a at their tips, respectively. These protuberances 31a-33a are adapted to fit within anchor holes 21a-23a formed on the latch member 21-23, respectively (see FIG. 2). Reference numerals 34, 34&#39;, 35, 35&#39;, 36 and 36&#39; represent respective lock-releasing pawls each formed in the shape of a rod. When the cabinet cover 2 is to be separated from the bottom plate 3, these pawls 34-36&#39; deflect the latch members 21-23 and facilitate the release of the engagement between the anchor pawls 31-33 and the latch members 21-23, as described below. 
     Reference numerals 37 and 39 represent respective cylindrical fitting portions. These fitting portions are formed on the bottom portion 30b of the bottom plate 3 and are integrated therewith. Further, they are adapted to engage tightly with the anchor protuberances 24 and 25 formed at the ceiling portion 20b of the cabinet cover 2, respectively, and tightly fix the cabinet cover 2 to the bottom plate 3. All of the bottom plate 3, anchor pawls 31-33, lock-releasing pawls 34 to 36&#39; and anchor portions 37 and 38 are integrally molded by insert-molding of a plastic using a plastic molding die. 
     Referring then to FIGS. 4, 5 and 6, lock and separation of the cabinet cover and the bottom plate will be described. 
     In locking, one of the frame end portions 30c of the bottom plate 3 and frame end portion 20c of the cabinet cover 2 are abutted together as shown in FIG. 5 and are set in such a manner that each hook-like protuberance 31a-33a of each anchor pawl 31-33 of the bottom plate 3 and each lock-releasing pawl 34 to 36&#39; enter the corresponding gaps 21b-23b of the cabinet cover 2. Under this state, when the cabinet cover 2 as well as the bottom plate 3 are pushed in the directions indicated by arrows A and B (see FIG. 5), respectively, the hook-like protuberances 31a-33a at the tips of the anchor pawls 31-33 start entering the mating gaps 21b-23b while flexing the latch members 21-23 inwardly. As the cabinet cover 2 and the bottom plate 3 are further pushed in the directions of the arrows A and B, respectively, these protuberances 31a-33a engage with the anchor holes 21a-23a formed in the latch members 21-23, respectively. In this instance, the anchor protuberances 24 and 25 (see FIG. 2) at the ceiling portion 20b of the cabinet cover 2 fit tightly within the cylindrical anchor portions 37 and 38 (see FIG. 3) on the bottom 30b of the bottom plate 3, respectively, whereby the cabinet cover 2 and the bottom plate 3 are locked integrally with each other (see FIG. 4). Incidentally, the lock-releasing pawls 34, 34&#39;, 35, 35&#39;, 36, 36&#39; enter the gaps 21b, 22b and 23b, respectively, and lie adjacent and the end portions 21c, 22c and 23c of the latch members 21, 22 and 23, respectively. 
     For separating the cabinet cover 2 from the bottom plate 3, forces in the directions of arrows A&#39; and B&#39; are applied to the frame end portions 20c, 30c of each of the cabinet cover 2 and the bottom plate 3, respectively, as shown in FIG. 6 so that they open on the hinges formed by the hook-like protuberances engaging the anchor holes of the latch members. In this case, the resilient anchor pawls 31-33 are thus pressed by the respective latch members 21-23, and are bent to some extent towards the frame side wall 30a, while the lock-releasing pawls 34, 34&#39;, 35, 35&#39;, 36, 36&#39; abut respective end portions 21c-23c of the latch members 21-23 and flex the receiving pawls 21-23 in the direction indicated by arrow C, respectively. Under this state, if the opening forces are further applied in the directions of the arrows A&#39; and B&#39; the hook-like protuberances 31a-33a formed on the anchor pawls 31-33 disengage from the anchor holes 21a-23a formed on the latch members 21-23 and the cabinet cover 2 is separated from the bottom plate 3. 
     In the foregoing description, though two lock-releasing pawls 34, 34&#39;, 35, 35&#39;, 36, 36&#39;, are used, only one lock-releasing pawl may be disposed. Further, the foregoing description deals with the case where the height of the lock-releasing pawls is smaller than that of the anchor pawls, if the height of the lock-releasing pawls is greater than that of the anchor pawls, this arrangement may make it possible to increase the force which the receiving pawls receive at the time of separation, to increase the flexing of the receiving pawls at the time of separation and thus to make the separation easier. 
     Moreover, in the above-described embodiment, the latching members are provided to the cabinet cover with the anchor pawls on the bottom plate, this arrangement may of course be reversed.