You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION  
       [0001]     The present invention relates to an opening and closing device for furniture provided with a latch adapted to facilitate operations to open and close movable parts of furniture, for brevity also called latch.  
       STATE OF THE ART  
       [0002]     Known latches have the function of facilitating opening or closing of the doors of furniture or drawers, according to the application for which they have been designed. These latches produce a slight contrasting force during the closing action that is accumulated by elastic elements capable of releasing it in a subsequent phase when the reverse operation of opening is implemented.  
         [0003]     If a latch is used to facilitate opening of a drawer or door, the latter is maintained in its closed position by suitable and known devices, which can either be separate from the latch or integral with it, for example hooks, magnets or the like.  
         [0004]     To open the drawer or door it is first necessary to apply a slight thrust to the drawer or door to release the latch, which returns the elastic energy accumulated during the closing operation and exerts a force on the drawer, generally created by springs, in the opening direction. An advantage of these devices is that they also make it possible not to use handles or other similar grasping elements on the drawer, which are not always appreciated for aesthetic or other reasons.  
         [0005]     Generally, one part of the elements constituting the latches is placed on fixed elements of the furniture to which the drawer belongs and another part on the drawer itself; moreover, these are constituted by a large number of elements that can make assembly by inexperienced personnel difficult.  
         [0006]     Some known latches are described in the documents DE 29507917U, DE 3816091, DE 19753319 and DE 10008350. However, these are devices that are complex to manufacture or to mount, some of which are too delicate to guarantee long-lasting operation.  
       SUMMARY OF THE INVENTION  
       [0007]     A main purpose of the present invention is therefore to produce a latch that overcomes the drawbacks indicated hereinbefore in a simple and inexpensive way and which is compact, sturdy and easy to apply to furniture, particularly to doors. Therefore, the present invention solves the problems mentioned hereinbefore by producing a latch with the characteristics claimed in claim  1 .  
         [0008]     In particular, the invention relates to a latch device, which can be locked and released by the action of an external force produced by one or more springs, comprising a slider. The slider is suitable to translate along a guide, integral with a fixed part of the furniture, inclined by an angle differing from zero with respect to the direction in which the external closing force is applied, and has a hook that may be caught by the movable part of the furniture. Moreover, elements suitable to lock or to release the slider according to the function implemented are provided between the slider and the container.  
         [0009]     Thanks to the solution of the invention, the latch has a simple and compact structure that can be applied simply to drawers or doors of furniture, thus guaranteeing exact positioning with respect to the parts and consequently its correct operation. It is also characterized by fast and easy mounting that can be performed without the use of special tools.  
         [0010]     The latch device is also sturdy and secure against any danger of becoming detached from the furniture element to which it is fixed. The latch also has compression springs or equivalent elastic means capable of controlling sufficient opening travel to allow easy manual grip to complete opening of the drawer or, if necessary, even to completely eliminate this action.  
         [0011]     The dependent claims describe preferred embodiments of the invention. 
     
    
     BRIEF DESCRIPTION OF THE FIGURES  
       [0012]     Further characteristics and advantages of the invention shall become more evident in the light of the detailed description of preferred, although not exclusive, embodiments of a latch, provided as non-limiting examples, with the aid of the accompanying drawings, wherein:  
         [0013]      FIG. 1  shows a side view of the latch device of the invention in a first operating position;  
         [0014]      FIG. 2  shows a side view of the latch device in  FIG. 1  in a second operating position;  
         [0015]      FIG. 3  shows an exploded axonometric view of the latch device in  FIG. 1 ;  
         [0016]      FIG. 4  shows an axonometric view of an element forming the latch device in  FIG. 1 ;  
         [0017]      FIG. 5  shows an axonometric view of an element forming the latch device in  FIG. 1 ;  
         [0018]      FIG. 6  shows a side section of an embodiment of the latch device of the invention;  
         [0019]      FIG. 7  shows an exploded axonometric view of the latch device in  FIG. 6 ;  
         [0020]      FIG. 8  shows four different operating phases of the latch according to the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0021]     With reference to the Figures cited, a latch device is represented, globally referenced with the reference T, generally, although not necessarily, fixed in one part thereof to a suitable structure of furniture  57 , and in another part thereof to a door  58 . It is however possible to kinetically invert the furniture parts on which the two parts forming the latch are fixed, however without departing from the sphere of the invention.  
         [0022]     The part of the latch T destined to be fixed to the furniture  57  with suitable means that are not described in detail, comprises a box or container  51  with a first groove or longitudinal cavity defining a sliding guide  60 . In the guide  60  there are the slider  52 , the helical spring  53  or another similar spring, which rests with one end on a shoulder or end of the guide and with the other end on the slider  52 , on which a shank  65  is provided to improve contact with the spring  53 . The container  51  has a cover  54  to close the open side of the guide  60 .  
         [0023]     In an advantageous embodiment part of the container is provided with an insert  50  essentially triangular in shape, which forms one side of the guide  60 , or part of one side, to facilitate manufacture and assembly. However, the insert  50  may alternatively also be eliminated to produce the container  51  in one piece.  
         [0024]     The guide  60  is inclined, with respect to the direction of application of the force F acting on the slider  52 , of an angle α, predetermined and defined according to the door or furniture part to be opened.  
         [0025]     There is provided, on the side of the guide  60 , a second groove defining a track  40  with different depths according to areas defining a path with a cam profile.  
         [0026]     The slider  52  also has a seat  71  with a rectangular plane, closed on the bottom, in which is placed a flat spring  72  bent in the shape of a V, on the outward facing side of which a ball  73  rests. The flat spring  72  thus pushes the ball  73  towards the bottom of the track  40  to make it travel along the path. A third groove  67  facilitates attachment of the spring  72  in its seat  71 .  
         [0027]     The track  40  is constituted by a longer longitudinal section  27 , the bottom of which varies in thickness and forms an inclined ramp terminating with a step  28 , which marks the limit separating it from a transverse section  29  slightly curved in the plane. The bottom of the transverse section  29  has two sections with levels  29 ′,  29 ″ slightly staggered, in the deepest of which  29 ″ a seat  30  is provided in the shape of a spherical cap. Running parallel to the section  27  is a second shorter longitudinal section  31 , which joins with the front part of the section  27  by means of a section  32 , the bottom of which is inclined, and at the end of which a short inclined ramp  33  is positioned to form a further step  34  in the connection point with the section  27 .  
         [0028]      FIG. 8  shows four positions of the latch, which show its operation between an open position and a locked position and again in an open position. The positions are indicated with the letters a), b), c), d) and also define four corresponding positions of the ball  73  along the track of the cover. Here the positions are shown as transparency views through the surface of the insert  50 . In position a) the hook  68  is in the outermost position, and therefore the hooking element  59  and the door connected to it can move freely. When the door  58  is pushed towards the closing position, the hooking element  59  knocks against the hook  68  with a force F, the component thereof parallel to the axis of the guide  60  pushes the slider  52  inside the guide  60  compressing the spring  53  to reach the position shown in  FIG. 2 .  
         [0029]     During this sliding, the hook  68  engages the hooking edge  62  of the hooking element  59 , catching it. At this point as the ball  73  cannot travel along the section  32  as it is obstructed by the step  34 , it travels along the ramp  27  and passes beyond the step  28 . Here inclination of the shank of the V-shaped spring  72  pushes the ball  73  along the deepest part  29 ″ of the section  29  until it enters the seat  30  in the form of spherical cap, becoming locked in the position c). In this position the slider  52  cannot slide in the groove and the hook  68  locks the hooking element  59 , so that the furniture part remains locked in its closed position even if no external force is applied thereto.  
         [0030]     The operation to open the door or drawer is instead carried out in the following way. After a successive slight thrust in the closing direction of the door, the ball  73  is moved from the seat  30  towards the shallowest part  29 ′ of the section  29  and the spring  72  pushes it into the position d). By removing the external force on the furniture part, the helical spring  53  pushes the slider  52  towards the outside and the ball  73  travels along the sections  31  and  32  passing beyond the ramp  33  and the step  34 , returning to the initial condition a) wherein the furniture part is released.  
         [0031]     Advantageously, the hooking element can be constituted by a cavity  61  partly open towards the opposed flat surfaces so as to easily produce the hooking edge  62 , even with a moulding process. The bottom  63  constitutes the thrust element of the hook  68  when the latch is in operation, making it slide in combination with the oblique movement in the inclined direction of the angle α, until it is positioned behind the hooking edge  62 , as shown in  FIGS. 2 and 6 .  
         [0032]     The cover  54  is also provided with shanks  76  suitable to be housed in corresponding holes  75  of the container  51  to allow integral assembly of the two parts.  
         [0033]     An embodiment of the latch conforming to the invention is shown in  FIGS. 6 and 7 . The container  81  has an essentially hollow trapezoidal shape inside which a sliding guide  90  is placed. One of the sides of the container is open and, in the mounted position of the latch, this side is closed by a triangular insert  80 , one of the sides thereof defining a side of the guide  90 . The triangular insert  80  also has the function of resting on the furniture, with a suitable reference stop  84 . Advantageously, although not necessarily, the track  40  can be provided on one side of the triangular insert  80 . This element is suitably fixed to the container  81  by means of fixing means of known type, not shown.  
         [0034]     From the description above it is apparent that the latch device of the invention is composed of a minimum number of components, is simple to assemble and can be mounted on furniture with an operation that is not difficult even for inexperienced personnel.  
         [0035]     The particular embodiments described herein do not limit the content of this application, which covers all the embodiments of the invention defined by the claims.

Summary:
Latch device composed of a container ( 51 ) in which there is a slider ( 52 ), inserted in a guide ( 60 ), controlled in translation by a spring ( 53 ) and comprising a hook ( 68 ) to catch a hooking element ( 59 ) placed on a door. A track ( 40 ), with the bottom defining the profile of a cam on one side of the guide ( 60 ), is travelled along by a ball ( 73 ) placed on the slider ( 52 ) and held pressed by a spring ( 72 ) against the bottom of the track ( 40 ) to determine the four open, closed, released and locked positions of the door according to the position of the ball in the track.