Patent Publication Number: US-6220065-B1

Title: Mechanical push button lock

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mechanical push button lock for controlling a locked/unlocked state of a specific element of a machine, and more particularly to a mechanical push button lock that not only provides two stage tactile impression but also has simple structure and low manufacturing tolerance. 
     2. Description of the Prior Art 
     A mechanical push button lock is used to control the locked/unlocked state of a specific element of a machine and is in widespread use in conventional industry and many products. Possible applications include mechanical push button lock for the cover of a crystal display projector, the mechanical push button lock of door, and so on. 
     The conventional structure of the mechanical push button lock comprises two categories. One category provides two stage tactile impression and the other category provides a simple structure and low tolerance. 
     First category, as FIG. 1 shows, comprises push key  10 , first cross rod  11 , second cross rod  12 , shaft  13 , first spring  14  and second spring  15 . Push key  10  located in one end of first cross rod  11 , and one end of first spring  14  is located on first cross rod  11 . Another end of first spring  14  is located on a fixed specific object  165  to settle first cross rod  11  in a specific region. Beside, the direction of first cross rod  11  points to second cross rod  12 . Moreover, second cross rod  12  rotates around shaft  13  and second spring  15  is used to settle second cross rod  12  in another specific region by connecting second cross rod  12  with fixed specific object  16 . Obviously, fixed specific object  16  and fixed specific object  165  can be the same object or be different objects, it depends on the design of mechanical push button lock. In addition, when the mechanical push button lock is locked then specific element 17  also is restricted by second cross rod  12  and is locked. 
     Therefore, it is obvious that when push key  10  is pressed first cross rod  11  slight slides along the pressed direction and first spring  14  is transfigured. Afterwards, when first cross rod  11  touches second cross rod  12  then not only does first cross rod  11  slide along the pressed direction but also second cross rod  12  rotates around shaft  13 . In other words, not only first spring  14  is transfigured but also second spring  15  is elongated. Then when second cross rod  12  rotates enough degrees, second cross rod  12  does not restrict specific element 17  and then specific element  17  is unlocked. 
     Consequently, this category provides two stage tactile impression that is obvious to a user because the required pushed force is small before the first cross rod  11  contacts second cross rod  12  and is large after the first cross rod  11  contacts second cross rod  12 . 
     The second category, as FIG. 2 shows, comprises push key  20 , spring  21 , shaft  22  and skeleton structure  23 . Push key  20  is located in one end of skeleton structure  23  and specific element  24  contacts another end of skeleton structure  23  when specific element  24  is locked by the mechanical push button lock, and shaft  22  penetrates through skeleton structure  23 . Moreover, spring  21  is used to settle skeleton structure  23  in a specific region by connecting skeleton structure  23  with fixed object  25 . 
     Obviously, when push key  20  is pressed then skeleton structure  23  rotates around shaft  23 , and when skeleton structure  23  rotates enough degrees then specific element  24  is relaxed and unlocked. Moreover, because only one spring  21  is transfigured, it provide a one stage tactile impression for user. 
     Comparing FIG.  1  and FIG. 2, it is crystal-clear that the structure of the first category is complicated and thus the cost of the first category is higher. In comparison, the structure of the second category is simplified and the cost of the second category is lower. Beside, the manufacturing process of the first category is more complicated for there are six component parts that need to be installed, but manufacturing tolerance is more sensitive in the second category because no spring is located between the push key and the shaft to absorb some manufacturing tolerance. 
     According to the previous discussion, it is obvious that both the conventional structures of the mechanical push button lock are required to improve, and it is therefore desired to develop a push button lock that provides two stage tactile impression, a simple structure and low manufacturing tolerances simultaneously. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention to mitigate and/or obviate these previously described disadvantages in the manner set forth in the following description of these preferred embodiments. 
     A primary object of the present invention is to present a mechanical push button lock that provides the user with a two stage tactile impression. 
     Another object of the present invention is to provide a mechanical push button lock that has a simple structure and a simple installation process. 
     A further object of the invention is to afford a mechanical push button that efficiently decreases the manufacturing tolerance. 
     These component parts of the provided invention comprise a push key, a shaft, a spring, a cross rod and an actuating rod. Moreover, these component parts are combined by the following rules: 
     (1) a cross rod is coupled with and actuating rod such that the cross rod is settled in a specific region. 
     (2) spring is used to connect the actuating rod and cross rod. 
     (3) a shaft penetrates through the cross rod. 
     (4) a push key is located in one end of actuating rod and a spring is located in another end of the actuating rod. 
     Further objectives and advantages of the present invention will become apparent as the following description proceeds, as well the features of novelty which is characterized in these claims annexed to and forming a part of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 briefly illustrates the configuration of a conventional mechanical push button lock, and a relation between the conventional mechanical push button and a specific element of a machine; 
     FIG. 2 briefly illustrates the configuration of another conventional mechanical push button lock, and the relation between that conventional mechanical push button and a specific element of a machine; 
     FIG. 3A to FIG. 3C are a series of schematic illustrations of the configuration of a proposed mechanical push button lock and the relation between the proposed mechanical push button and a specific element of a machine; where FIG. 3A illustrates the case that both the proposed mechanical push button and the specific elements also are locked; FIG. 3B illustrates the case that the proposed mechanical push button is pressed but the specific element is not relaxed; and FIG. 3C illustrates the case that both the proposed mechanical push button and the specific elements are unlocked; and 
     FIG. 4 is a briefly illustration about configuration of another proposed mechanical push button lock and relation between the proposed mechanical push button and a specific element of a machine, where the proposed mechanical push button is not be pressed and the specific element is locked. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In order to elucidate these objects of the proposed mechanical push button lock that is used to control the locked/unlocked state of a specific element of a machine, some figures and some embodiments are employed to illustrate the invention and are explained in the following paragraphs. 
     Referring to FIG. 3A to FIG. 3C, it is crystal-clear that the proposed mechanical push button lock comprises push key  30 , actuating rod  31 , cross rod  32 , spring rod  33  and shaft  34 . These component parts are combined by the following rules: 
     First rule: actuating rod  31  couples with cross rod  32  in one end of actuating rod  31 . Where possible, the coupling between actuating rod  31  and cross rod  32  is achieved by extending cross rod  32  through a hole of actuating rod  31  and actuating rod  31  through another hole of cross rod  32 . Herein, FIG. 3A to FIG. 3C illustrate the previous case. 
     Second rule: push key  30  is located in another end of actuating rod  31 , where the shape of actuating rod  31  can be any shape. Beside, not only is push key  30  located in one end of actuating rod  31 , but actuating rod  31  also extends through one hole of cross rod  32  in another end of actuating rod  31 . No matter how, when actuating rod  31  extends through one hole of cross rod  32 , the shape of the actuating rod  31  must as paddle-like shape and a bottle-like shape. In the case, diameter of the hole must be smaller than a width of the wide part of the paddle-like actuating rod  31 . 
     Third rule: spring  33  connects actuating rod  31  and cross rod  32 . Herein, spring  33  and push key  30  are located in opposite ends of actuating rod  31 . 
     Fourth rule: shaft  34  penetrates through cross rod  32  such that cross rod  32  rotates around shaft  34 . 
     Fifth rule: a location of spring  33  and specific element  35  must satisfy the requirement that the direction of a torque induced by spring  33  must be opposite to a direction of another torque induced by specific element  35  of a machine. 
     Sixth rule: when the mechanical push button locked is locked then specific element  35  contacts cross rod  32  such that specific element  35  is locked by the mechanical push button lock. Besides, the quantity of the torque that induced by spring  33  must be equal to the quantity of the torque that induced by specific element  35 . 
     Obviously, because cross rod  32  is coupled with actuating rod  31 , cross rod  32  is restricted in a specific region and it is not necessary to connect cross rod  32  with any specific object. In other words, the structure and manufacturing process of the invention is simpler than the first category of conventional mechanical push button lock. 
     FIG. 3A shows the case that the provided mechanical button lock does not pressed and be locked. Although there are two torques acting on cross rod  32 , cross rod  32  does not rotate because the torque induced by spring  33  is totally offset by the torque induced by specific element  35 . Therefore, specific element  35  is locked by the mechanical push button lock. 
     As FIG. 3B shows, when push key  30  is pressed, actuating rod  31  slides along the pushing direction and then spring  33  is elongated. Obviously, actuating rod  31  will continually slide until actuating rod  31  directly touches cross rod  32 . No matter how, specific element  35  still is not relaxed because the location of cross rod  32  is not changed by pressing push key  31 . Obviously, in the stage that FIG. 3B shows, the force that is applied to push key  30  only must be larger than opposite the direction components of elastic force of elongate spring  33 . 
     No matter how, when press key  30  is continually pressed, not only is spring  33  elongated but also cross rod  32  is pushed and rotates around shaft  34 , as FIG. 3C shows. Therefore, the force that applied in push key  30  not only needs to overcome opposite direction components of elastic force of elongated spring  33  that act on actuating rod  31 , but also needs to overcome the torque induced by elongated spring  33  and acting on cross rod  32 . Obviously, the required force in the stage is larger than the required force in the previous stage. In other words, the provided invention can provide a user with a two stage tactile impression. 
     Furthermore, because actuating rod  31  must directly push cross rod  32  before cross rod  32  rotates around shaft  34 , it is obvious that both the sliding distance and sliding direction of actuating rod  31  are not restricted in a strict range. In other words, manufacturing tolerance of position of the both actuating rod  31  and push key  30  does not directly and sensitively affect the action of the provided mechanical push button lock. 
     FIG. 4 illustrates another possible structure of the proposed mechanical push button lock. Owing to the fact that the mechanism of the embodiment is equal to that of the previous embodiment, only the case that both the mechanical push button and the specific element are locked is illustrated. 
     To compare with the previous embodiment, the embodiment has some characteristics: 
     First, the shape of actuating rod  40  is paddle-like 
     Second, hole  41  locates in one end of cross rod  42  and paddle-like actuating rod  40  extends through hole  41  by the narrow end of paddle-like actuating rod  40 . 
     Third, push key  43  is located in a wide end of paddle-like actuating rod  40 . 
     Fourth, bulge  44  is located on cross rod  42  and spring  45  connects a tip of bulge  44  and the narrow end of paddle-like actuating rod  40 . 
     Fifth, hook structure  46  is located in another end of cross rod  42  to secure specific element 47 . 
     In addition, owing to the fact that the mechanical push button lock is relaxed when cross rod  42  is pushed away by paddle-like actuating rod  40 , when press key  43  is pressed and slides enough distance, cross rod  42  is pushed by paddle-like actuating rod  42  and rotates around shaft  48 . 
     Moreover, owing to the fact that torque is the product of force and distance, it is better to increase the distance between shaft  46  and the join of spring  45  and cross  42  rod to provide a large torque and decrease the force that a user need to apply on push key  43 . 
     A various possible embodiments may be made of the above invention without departing from the scope of the invention, it is to be understood that all matter herein described or shown in the accompanying drawings is to be interpreted as illustrate and not in a limiting sense. Thus, it will be appreciated that these drawings are exemplary of a preferred embodiments of this invention.