Patent Publication Number: US-2015068307-A1

Title: Resonance device having drop resistive protection

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Taiwan application serial no. 102132601, filed on Sep. 10, 2013. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to a resonance device, and more particularly, to a resonance device having drop resistive protection. 
     2. Description of Related Art 
     In recent years, along with development of electronic products such as smart phones, tablet PCs and somatosensory game machines, etc., micro-electromechanical system (MEMS) inertial sensors such as accelerometers and gyroscopes, etc. are widely applied in the aforementioned electronic products, and a market demand thereof has grown significantly year by year. Under intense market competition, related applications of the MEMS inertial sensors have higher demand on quality of the MEMS inertial sensors. Regarding a piezo-resistive accelerometer, acceleration of an apparatus is measured through a resistance variation amount of a component therein. 
       FIG. 1  is a schematic cross-sectional diagram of a conventional known practice an MEMS gyroscope and  FIG. 2  is a top-view diagram of partial parts of the gyroscope in  FIG. 1 . Referring to  FIGS. 1 and 2 , a mass  52  of a gyroscope  50  is connected to a connection portion  56   a  of a base  56  through elastic portions  54 . By means of the elastic deformation characteristic of the elastic portions  54 , the mass  52  is driven to be resonated, and further the Coriolis force during rotating of the gyroscope  50  is measured in the resonance operation mode so as to calculate the angular velocity of the gyroscope  50 , wherein the detection and calculation principle is known in the related technical field. U.S. Pat. No. 5,668,318, for example, discloses the related MEMS gyroscope technology. 
     When the apparatus drops, if the mass  52  in the gyroscope  50  instantly generates a large displacement due to an impact force of the drop, the elastic portion  54  is probably damaged due to excessive pulling. In this way, in some drop resistive designs, a moving range of the mass  52  can be limited by decreasing a gap G 1  between a first base body  56   b  and the mass  52  and decreasing a gap G 2  between a second base body  56   c  and the mass  52 , so as to avoid the mass  52  from instantly generating a large displacement due to the impact force caused by drop of the mass  52 . However, when the gaps G 1  and G 2  are small, an excessive damping effect caused by the air between the mass  52  and the first base body  56   b , which reduces the resonance respond of the mass  52  due to the air damping and the measuring sensitivity and accuracy of the angular velocity of the gyroscope  50 . 
     SUMMARY OF THE INVENTION 
     Accordingly, the invention is directed to a resonance device with good resonance capability and drop resistive protection function. 
     A resonance device of the invention includes a base, a mass, a plurality of elastic portions and at least one end surface. The mass has at least one end surface. The elastic portions are connected between the mass and the base, in which the mass is adapted to resonate in a first direction such that the elastic portions are elastically deformated. The block portion is disposed at the base and extends towards the end surface to be aligned to the end surface, in which the gap between the base and the end surface in the first direction is greater than the gap between the block portion and the end surface in the first direction, and the block portion is adapted to block the end surface to limit the moving range of the mass. 
     In an embodiment of the invention, the base includes a first base body, a second base body and a connection portion. The mass is located between the first base body and the second base body and the block portion is fixed at the first base body or the second base body. The connection portion is fixed between the first base body and the second base body, in which each of the elastic portions is connected between the mass and the connection portion. 
     In an embodiment of the invention, the connection portion is adhered to the first base body and the second base body. 
     In an embodiment of the invention, a number of the at least one block portion is plural, the at least one end surface includes a top surface of the mass and a bottom surface of the mass, a part of the block portions are aligned to the top surface and another part of the block portions are aligned to the bottom surface. 
     In an embodiment of the invention, the resonance device further includes at least one block structure, in which the mass has a plurality of side surfaces, the elastic portions are respectively connected to the side surfaces, the block structure is disposed at the base and aligned to at least one side surface, and the block portion is adapted to block the corresponding end surface to limit the moving range of the mass. 
     In an embodiment of the invention, the base includes a first base body, a second base body and a connection portion, the mass is located between the first base body and the second base body, the connection portion is fixed between the first base body and the second base body and the block structure is fixed at the first base body or the second base body, the connection portion is adhered to the first base body in the first direction, the connection portion is adhered to the second base body in the first direction, and each of the side surfaces is parallel to the first direction. 
     In an embodiment of the invention, a number of the at least one block portion is plural, and the block portions are respectively aligned to the side surfaces. 
     In an embodiment of the invention, the block structure has two block surfaces, and the two block surfaces are respectively aligned to the two adjacent side surfaces. 
     In an embodiment of the invention, the block structure extends from the block portion. 
     In an embodiment of the invention, the length of the block structure in the first direction is greater than the gap between the block portion and the end surface in the first direction. 
     In an embodiment of the invention, the end surface is perpendicular to each of the side surfaces, the block structure is adapted to block the corresponding side surface to limit the moving range of the mass in a second direction, and the second direction is inclined to each of the side surfaces and the end surface. 
     In an embodiment of the invention, each of the elastic portions extends in an axis and the axis does not pass through mass center of the mass. 
     In an embodiment of the invention, the block portion is formed through an exposure process and an etching process. 
     Based on the depiction above, the resonance device of the invention has block portions on the base thereof able to block the end surface of the mass to limit the moving range of the mass, such that the mass is avoided to have an instant large displacement due to the dropping impact force, so as to avoid a pulling damage of the elastic portions due to excessive displacement of the mass. In this way, the drop resistive protection function can be realized. Since in the resonance device of the invention, the mass is blocked to limit the moving range of the mass by using the block portions on the base, there is no need to reduce the gap between the whole base and the end surface of the mass for blocking the mass. As a result, the damping effect caused by the air between the end surface of the mass and the base is not excessive so as to ensure a smooth resonance of the mass. 
     In order to make the features and advantages of the present invention more comprehensible, the present invention is further described in detail in the following with reference to the embodiments and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional diagram of a conventional MEMS gyroscope. 
         FIG. 2  is a top-view diagram of partial parts of the gyroscope in  FIG. 1 . 
         FIG. 3  is a schematic cross-sectional diagram of a resonance device according to an embodiment of the invention. 
         FIG. 4  is a top-view diagram of partial parts of the gyroscope in  FIG. 3 . 
         FIG. 5  is a schematic cross-sectional diagram of a resonance device according to another embodiment of the invention. 
         FIG. 6  is a top-view diagram of partial parts of the gyroscope in  FIG. 5 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 3  is a schematic cross-sectional diagram of a resonance device according to an embodiment of the invention and  FIG. 4  is a top-view diagram of partial parts of the gyroscope in  FIG. 3 . Referring to  FIGS. 3 and 4 , a resonance device  100  of the embodiment is, for example, an MEMS gyroscope and includes a base  110 , a mass  120  and a plurality of elastic portions  130 . The base  110  includes a first base body  112 , a second base body  114  and a connection portion  116 . The connection portion  116  and the first base body  112  are adhered to each other in a first direction D 1  as shown in  FIG. 3  through an adhesive  150   a  and the connection portion  116  and the second base body  114  are adhered to each other in the first direction D 1  through an adhesive  150   b,  so that the connection portion  116  is fixed between the first base body  112  and the second base body  114 . The mass  120  is located between the first base body  112  and the second base body  114  and has a plurality of side surfaces  120   a  and two opposite end surfaces, in which the two end surfaces are the top surface  120   b  and bottom surface  120   c  of the mass  120  and are perpendicular to each of the side surfaces  120   a.    
     The elastic portions  130  are respectively connected to the side surfaces  120   a  and connected to the connection portion  116  of the base  110 . The base  110  is to be driven in the first direction D 1  to resonate such that the elastic portions  130  are elastically deformed. In such resonance operation mode, the Coriolis force of the resonance device  100  during rotating can be measured to further calculate the angular velocity of a device with the resonance device  100 , wherein the detection and calculation principle is a known technique of the belonging field, which is omitted to describe. 
     The resonance device  100  of the embodiment further includes a plurality of block portions  160 , the partial block portions  160  are fixed at the first base body  112  and extend towards the top surface  120   b  of the mass  120  to be aligned to the top surface  120   b,  while the rest block portions  160  are fixed at the second base body  114  and extend towards the bottom surface  120   c  of the mass  120  to be aligned to the bottom surface  120   c.  The gap G 3  between the base  110  and the top surface  120   b  of the mass  120  in the first direction D 1  is greater than the gap G 5  between the block portions  160  and the top surface  120   b  of the mass  120 , and the gap G 4  between the base  110  and the bottom surface  120   c  of the mass  120  in the first direction D 1  is greater than the gap G 6  between the block portions  160  and the bottom surface  120   c  of the mass  120  in the first direction D 1 . 
     Under the above configuration, the block portions  160  are able to block the top surface  120   b  and bottom surface  120   c  of the mass  120  to limit the moving range of the mass  120 , such that the mass  120  is avoided to have an instant large displacement due to a dropping impact force, so as to avoid a pulling damage of the elastic portions  130  due to an excessive displacement of the mass  120 . As a result, the drop resistive protection function is realized. Since in the resonance device of the embodiment, the mass  120  is blocked to limit the moving range of the mass  120  by using the block portions  160  on the base  110 , there is no need to reduce the gaps between the whole base  110  and the top surface  120   b  and bottom surface  120   c  of the mass  120  for blocking the mass  120 . Thus, the base  110  and the mass  120  have larger gaps G 3  and G 4 . As a result, the damping effect caused by the air between the base  110  and the mass  120  is not excessive so as to ensure the mass  120  smoothly making resonance. The invention does not limit the number and arrangement way of the block portions  160 . In other embodiments, the block portions  160  can have other appropriate number and other arrangement ways. In addition, in other embodiments, the resonance device  100  can be a quartz crystal oscillator or other resonance devices, which the invention is not limited to. 
       FIG. 5  is a schematic cross-sectional diagram of a resonance device according to another embodiment of the invention and  FIG. 6  is a top-view diagram of partial parts of the gyroscope in  FIG. 5 . In the resonance device  200  of  FIG. 5 , the dispositions and the action ways of a base  210 , a first base body  212 , a second base body  214 , a connection portion  216 , a mass  220 , elastic portions  230 , an adhesive  250   a,  an adhesive  250   b  and block portions  260  are the same as the dispositions and the action ways of the base  110 , the first base body  112 , the second base body  114 , the connection portion  116 , the mass  120 , the elastic portions  130 , the adhesive  150   a,  the adhesive  150   b  and the block portions  160 , which are omitted to describe. The difference of the resonance device  200  from the resonance device  100  rests in that the resonance device  200  further includes a plurality of block structures  240 . The partial block structures  240  are disposed at the first base body  212  and the rest block structures  240  are disposed at the second base body  214 . As shown in  FIG. 5 , these block structures  240  are respectively extended from the block portions  260 , and the length of the block structures  240  in the first direction D 1 ′ is greater than the gap G 7  between the block portions  260  and the top surface  220   b  of the mass  220  in the first direction D 1 ′ and greater than the gap G 8  between the block portions  260  and the bottom surface  220   c  of the mass  220  in the first direction D 1 ′, so that these block structures  240  can be respectively aligned to the side surfaces  220   a  of the mass  220 , in which each of the block structures  240 , for example, has two block surfaces  240   a  respectively aligned to the two adjacent side surfaces  220   a.    
     Under the above configuration, the block structures  240  are able to block the side surfaces  220   a  of the mass  220  to limit the moving range of the mass  220 , such that the mass  220  is avoided to have an instant large displacement due to a dropping impact force, so as to avoid a pulling damage of the elastic portions  230  due to an excessive displacement of the mass  220 . The block structures  240  can be formed by using an exposure process or an etching process so as to have better dimension accuracy and make the gap between the block structures  240  and the side surfaces  220   a  of the mass  220  appropriate, which can accurately limit the moving range of the mass  220  to advance the drop resistive protection function of the resonance device  200 . 
     In more details, the connection portion  216  and the first base body  212  are adhered to each other through the adhesive  250   a  in the first direction D 1 ′ as shown in  FIG. 5 , and the connection portion  216  and the second base body  214  are adhered to each other through the adhesive  250   b  in the first direction D 1 ′. Each of the side surfaces  220   a  of the mass  220  is parallel to the first direction D 1 ′. Thus, the dimension error produced when the first base body  212  and second base body  214  are adhered to the connection portion  216  unlikely affects the accuracy of the gaps between all the side surfaces  220   a  and the block structures  240 . 
     In the embodiment, partial elastic portions  230  extend in an axis A 1  (referring to  FIGS. 5 and 6 ), while the rest elastic portions  230  extend in another axis A 2  (referring to FIG. 
       6 ), wherein both the axis A 1  and the axis A 2  do not pass through the mass center M of the mass  220 . Therefore, when the mass  220  suffers a dropping impact force, the mass  220  easily has a displacement along an inclined direction. The inclined direction can be, for example, the second direction D 2  in  FIG. 5  or other inclined directions. In particular, the inclined direction is the one inclined to each of the side surfaces  220   a,  the top surface  220   b  and the bottom surface  220   c  of the mass  220 . When the mass  220  has displacement along the inclined direction, the block structures  240  are suitable to block the side surfaces  220   a  of the mass  220  to limit the moving range of the mass  220  along the inclined direction, which can avoid the dragging and damaging of the elastic portions  230  caused by the excessive displacement of the mass  220  in the first direction D 1 ′. 
     In summary, the resonance device of the invention has block portions on the base thereof able to block the end surface of the mass to limit the moving range of the mass, such that the mass is avoided to have an instant large displacement due to the dropping impact force, so as to avoid a pulling damage of the elastic portions due to excessive displacement of the mass. In this way, the drop resistive protection function can be realized. Since in the resonance device of the invention, the mass is blocked to limit the moving range of the mass by using the block portions on the base, there is no need to reduce the gap between the whole base and the end surface of the mass for blocking the mass. As a result, the damping effect caused by the air between the base and the end surface of the mass is not excessive so as to ensure a smooth resonance of the mass. In addition, by further disposing the block structures on the block portions of the resonance device, the side surfaces of the mass are blocked by the block structures so as to limit the moving range of the mass and further increase the drop resistive protection function. 
     It will be apparent to those skilled in the art that the descriptions above are several preferred embodiments of the invention only, which does not limit the implementing range of the invention. Various modifications and variations can be made to the structure of the invention without departing from the scope or spirit of the invention. The claim scope of the invention is defined by the claims hereinafter.