Abstract:
A haptic feedback actuator includes: a vibration plate provided on one surface of a haptic device and transferring vibration; and an actuator provided such that the vibration plate is interposed between the actuator and the haptic device and excited according to a change in the contact pressure of the haptic device to generate vibration.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 10-2009-0096965 filed on Oct. 12, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a haptic feedback actuator, a haptic device, and an electronic device. 
         [0004]    2. Description of the Related Art 
         [0005]    Recently, the use of touch-type devices allowing for an inputting operation in electronic devices (or home appliances) through a touch (contact) operation is generalized according to the demands of users who desire to use electronic appliances in a simpler manner. 
         [0006]    Currently, a haptic feedback device follows the concept of providing an intuitional user interface experience and diversifying types of contact feedback, in addition to facilitating the concept of performing an inputting operation through a touch. 
         [0007]    The haptic feedback device has many advantages: It can save space, accomplish an improvement in manipulation and simplicity, allow for a simple change in specification, have a high level of user recognition, and have good interworkability with IT devices. 
         [0008]    With such advantages, the haptic feedback device is commonly employed in electronic devices used in home computers, traffic note issuing devices, public information services, medical equipment, mobile communications purposes, etc. 
         [0009]    In general, the related art electronic device uses a vibration motor to implement a haptic function. The vibration motor was devised to vibrate the entire electronic device body, so, in order to increase vibration force, the size of a mass body must be increased. 
         [0010]    Also, the vibration motor has an additional problem in that it increases unit cost, must be installed in a limited internal space of an electronic device, and is ineffective in terms of power consumption as it is designed to vibrate the entire electronic device. 
         [0011]    Also, recently, as user interfaces are advancing and the functions of electronic devices have become diversified and complicated, the vibration motor simply devised to vibrate the entire electronic device cannot come up with the implementation of various types of feedback according to the diversified functions. 
       SUMMARY OF THE INVENTION 
       [0012]    An aspect of the present invention provides a haptic feedback actuator including a vibration plate attached to a haptic device that implements a haptic function to transfer vibrations and an actuator applying vibrations to the vibration plate, a haptic feedback device including the haptic feedback actuator, and an electronic device. 
         [0013]    Another aspect of the present invention provides a haptic feedback device including an actuator disposed at a central portion of a haptic device that implements a haptic function to enhance vibration efficiency, and an electronic device. 
         [0014]    Another aspect of the present invention provides a haptic feedback device providing an optimum bonding condition for a haptic device that implements a haptic function to generate a stable amount of vibrations and a haptic feedback actuator, and an electronic device. 
         [0015]    According to an aspect of the present invention, there is provided a haptic feedback actuator including: a vibration plate provided on one surface of a haptic device and transferring vibrations; and an actuator provided such that the vibration plate is interposed between the actuator and the haptic device and excited according to a change in the contact pressure with the haptic device to generate vibrations. 
         [0016]    The vibration plate may be attached and disposed along the edge portion forming the shape of the haptic device. 
         [0017]    The vibration plate attached and disposed along the edge portion in a lengthwise direction of the haptic device may include a plurality of branch lines, and a slit may be formed between the plurality of branch lines. 
         [0018]    The actuator may be attached to mutually adjacent branch lines, among the plurality of branch lines, and the width of the branch lines and that of the actuator may be equal. 
         [0019]    The vibration plate may be longer than the actuator. 
         [0020]    The actuator may be a piezo-actuator or a polymer actuator. 
         [0021]    The piezo-actuator may be a bar-shaped ceramic stacked body including ceramic layers and an electrode interposed between the ceramic layers, and polarizations (or pollings) of the ceramic layers may be formed in the same direction. 
         [0022]    According to another aspect of the present invention, there is provided a haptic feedback device including: a display panel provided as a haptic device requiring vibrations; an actuator excited according to a change in contact pressure with the display panel to generate vibrations; and a vibration plate disposed between the display panel and the actuator and amplifying vibrations generated from the actuator to transfer the amplified vibrations to the display panel. 
         [0023]    The vibration plate may be attached and disposed along the edge portion forming the shape of the display panel. 
         [0024]    The vibration plate attached and disposed along the edge portion in a lengthwise direction of the display panel includes a plurality of branch lines, and a slit may be formed between the plurality of branch lines. 
         [0025]    The actuator may be attached to mutually adjacent branch lines, among the plurality of branch lines, and the width of the branch lines and that of the actuator may be equal. 
         [0026]    The vibration plate may be longer than the actuator. 
         [0027]    The actuator may be a piezo-actuator or a polymer actuator. 
         [0028]    The piezo-actuator may be a bar-shaped ceramic stacked body including ceramic layers and an electrode interposed between the ceramic layers, and polarizations (or pollings) of the ceramic layers may be formed in the same direction. 
         [0029]    According to another aspect of the present invention, there is provided an electronic device including: a case having an internal space formed therein; a display panel accommodated to be disposed within the case; an actuator excited according to a change in contact pressure with the display panel to generate vibrations; and a vibration plate interposed between the display panel and the actuator, wherein the vibration plate is longer than the actuator. 
         [0030]    The vibration plate may include a plurality of branch lines demarcated by a slit, and the actuator may be attached to be disposed on the branch lines. 
         [0031]    The actuator may be a piezo-actuator or a polymer actuator. 
         [0032]    The piezo-actuator may be a ceramic stacked body including ceramic layers and an electrode interposed between the ceramic layers, and polarizations (or pollings) of the ceramic layers may be formed in the same direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0034]      FIG. 1  is an exploded perspective view of a mobile communications terminal or an electronic device, according to an exemplary embodiment of the present invention; 
           [0035]      FIG. 2  is a perspective view schematically showing a haptic feedback device mounted in a case of the mobile communications terminal according to an exemplary embodiment of the present invention; 
           [0036]      FIG. 3  is a perspective view schematically showing the haptic feedback device according to an exemplary embodiment of the present invention; 
           [0037]      FIGS. 4(   a ) and  4 ( b ) are side views showing actuators and vibration plates of an haptic feedback actuator having different lengths according to an exemplary embodiment of the present invention; 
           [0038]      FIGS. 5(   a ) and  5 ( b ) are an enlarged sectional view of a portion of  FIG. 4(   b ), schematically showing an operational shape of the haptic feedback actuator; 
           [0039]      FIG. 6  is a graph displaying the amount of displacement over vibration frequency of the haptic feedback actuator of  FIGS. 4(   a ) and  4 ( b ); 
           [0040]      FIGS. 7(   a ) and  7 ( b ) are schematic perspective views showing a changed disposition location of the actuator of the haptic feedback actuator according to an exemplary embodiment of the present invention; 
           [0041]      FIG. 8  is a side view for explaining a disposition location of the actuator according to an exemplary embodiment of the present invention; 
           [0042]      FIG. 9  is a graph displaying the amount of displacement over vibration frequency of the haptic feedback actuator of  FIGS. 7(   a ) and  7 ( b ); 
           [0043]      FIG. 10  is a schematic sectional view showing bonding of the haptic feedback device according to an exemplary embodiment of the present invention; and 
           [0044]      FIG. 11  is a graph displaying the amount of displacement over vibration frequency of the haptic feedback actuator measured according to the types of bonding materials used in the haptic feedback device according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0045]    Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. The invention may however be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components. 
         [0046]    A haptic feedback actuator, as well as a haptic feedback device and an electronic device having the haptic feedback actuator according to exemplary embodiments of the present invention will now be described with reference to  FIGS. 1 to 11 . 
         [0047]    [Electronic Device] 
         [0048]      FIG. 1  is an exploded perspective view of a mobile communications terminal, an electronic device, according to an exemplary embodiment of the present invention.  FIG. 2  is a perspective view schematically showing a haptic feedback device mounted in a case of the mobile communications terminal according to an exemplary embodiment of the present invention.  FIG. 3  is a perspective view schematically showing the haptic feedback device according to an exemplary embodiment of the present invention. 
         [0049]    In the following description, a mobile communications terminal  10  will be taken as an electronic device according to an exemplary embodiment of the present invention, but without being limited thereto, the electronic device can be also applicable to a general haptic device generating a change in vibration according to a user contact with devices such as various OA devices, medical equipment, mobile communications devices, traffic note issuing device, or the like. 
         [0050]    The mobile communications terminal  10  as an electronic device will now be described in detail. 
         [0051]    With reference to  FIGS. 1 to 3 , the mobile communication terminal  10 , an electronic device, according to an exemplary embodiment of the present invention may include cases  12  and  14 , a display panel  22 , an actuator  60 , and a vibration plate  40 . 
         [0052]    The cases  12  and  14  may include a front case  12  and a rear case  14 . The front case  12  and the rear case  14  may be coupled to form an internal space therebetween. 
         [0053]    A display panel  22  serving as a haptic device  20 , and a circuit board (not shown) that can drive a haptic feedback actuator  30  can be mounted in the internal space. 
         [0054]    Here, the haptic device  20 , a mechanism requiring vibration, is an internal element of the mobile communication terminal  10  that requires a reaction upon external contact pressure. 
         [0055]    Besides the display panel  22  of the mobile communication terminal  10 , the haptic device  20  may also be an input device, an OA device, a vending machine, a bed, a card, a driving device, a ticket, etc. 
         [0056]    In the mobile communications terminal  10 , an electronic device according to the present exemplary embodiment, the display panel  22  providing an image is employed as the haptic device  20 . Namely, when contact pressure is changed according to a contact applied to the display panel  22 , the display panel  22  reacts haptically to the contact. 
         [0057]    In order to allow the display panel  22  to make the react haptically, the actuator  60  must generate vibrations. A substantial vibration generation principle of the actuator  60  will be described later. 
         [0058]    The vibration plate  40  may transfer the vibration generated from the actuator  60  to the display panel  22 . The actuator  60  may be directly attached to the display panel  22  to make the display panel  22  vibrate, but it can be selectively used as necessary to reduce an impact caused by vibration or to amplify vibration. 
         [0059]    Namely, the vibration plate  40  may be fabricated by injection-molding an impact-lessening material; however, the present invention is not intended to be limited thereto. Also, the thickness of the vibration plate  40  may be adjusted in consideration of an interaction with the actuator  60 . Experimentation shows that vibrations increased rapidly when the thickness of the vibration plate was smaller than 0.2 mm, so the thickness of the vibration plate  40  can be properly selected depending on the requirement range of vibration. 
         [0060]    The haptic feedback actuator  30  and the haptic device will now be described in detail. The detailed characteristics of the haptic feedback actuator and the haptic device described hereafter can be all applicable to the electronic device of the present invention. 
         [0061]    [Haptic Feedback Actuator and Haptic Feedback Device] 
         [0062]    The haptic feedback actuator  30  according to an exemplary embodiment of the present invention may include the vibration plate  40  and the actuator  60 . Also, a haptic feedback device  50  may include the haptic device  20  to which a contact pressure is applied and the haptic feedback actuator  30  that vibrates the haptic device  20 . 
         [0063]    Here, the vibration plate  40  of the haptic feedback device  50  may be optional. 
         [0064]    The vibration plate  40  has been described above in detail with respect to the mobile terminal  10 , and may be attached along the edges constituting the configuration of the haptic device  20 . 
         [0065]    Namely, as shown in  FIG. 3 , the vibration plate  40  may be formed as a thin strip and disposed along the edges in a rectangular shape of the display panel  22 . 
         [0066]    Here, it is assumed that a longer side of the rectangular display panel  22  is defined as a lengthwise direction and a shorter side is defined as a widthwise direction. 
         [0067]    In detail, the vibration plate  40  may have a plurality of branch lines  42  and  44  at the edge portion in the lengthwise direction of the display panel  22 , the haptic device  20 , and a slit  43  may be formed between the plurality of branch lines  42  and  44 . The branch lines  42  and  44  may have substantially the same width, and the bar-shaped actuator  60  having almost the same width as that of the branch lines  42  and  44  may be attached to be disposed on the branch lines  42  and  44 . In this case, the actuator  60  may be disposed to be parallel with relation to the branch lines  42  and  44 . 
         [0068]    The actuator may be configured as a piezo-actuator or a polymer actuator so as to be excited according to a change in a contact pressure of the haptic device  20  to generate vibration. 
         [0069]    Meanwhile, the length of the actuator  60  and the vibration plate  40  and the disposition location of the actuator  60  at the haptic device  20  are important factors in determining the amount of vibrations of the haptic device  20 . 
         [0070]    A change in the amount of vibrations according to the length of the actuator  60  and the vibration plate  40  will now be described in detail. 
         [0071]      FIGS. 4(   a ) and  4 ( b ) are side views showing actuators and vibration plates of the haptic feedback actuator having different lengths according to an exemplary embodiment of the present invention.  FIGS. 5(   a ) and  5 ( b ) are an enlarged sectional view of a portion of  FIG. 4(   b ), schematically showing an operational shape of the haptic feedback actuator.  FIG. 6  is a graph displaying the amount of displacement over vibration frequency of the haptic feedback actuator of  FIGS. 4(   a ) and  4 ( b ). 
         [0072]      FIG. 4(   a ) shows an exemplary embodiment in which the length of the vibration plate  40  and that of the actuator  60  are equal, and  FIG. 4(   b ) shows an exemplary embodiment in which the vibration plate  40  is longer than the actuator  60 . 
         [0073]    Here, the amount of displacement (μm) of the haptic device  20  according to the number of vibrations by using a piezo-actuator as the actuator  60  was measured. 
         [0074]    As shown in  FIGS. 5(   a ) and  5 ( b ), the piezo-actuator is a ceramic stacked body formed by stacking ceramic layers  62  and  64  on both sides of an electrode  63  made of silver (Ag) or other impurities, and pollings (or polarizations) of the ceramic layers  62  and  64  are formed in the same direction. 
         [0075]    As the pollings of the ceramic layers  62  and  64  are formed in the same direction, the amount of vibration increases when compared with the case where the pollings are formed in the opposite directions, so the amount of vibration can be properly selected according to the requirement range of vibration. 
         [0076]    When pressure is applied to the piezo-actuator in the state that the pollings of the ceramic layers  62  and  64  are formed in the same direction, the actuator  60  is displaced in the lengthwise direction while the vibration plate  40  is not displaced. 
         [0077]    For this reason, when the actuator  60  is displaced in the lengthwise direction, the haptic feedback actuator  30  vibrates up and down. 
         [0078]      FIGS. 6(   a ) and  6 ( b ) are graphs showing results obtained by measuring the amount of vertical displacement of the haptic device  20  while increasing the frequency of vibration according to the exemplary embodiment of  FIGS. 4(   a ) and  4 ( b ). 
         [0079]    With reference to  FIGS. 6(   a ) and  6 ( b ), it is noted that the amount of displacement in the embodiment of  FIG. 4(   a ) is greater than that of  FIG. 4(   b ). 
         [0080]    Thus, the length of the vibration plate  40  and the actuator  60  can be properly selected to be employed according to the vibration requirement range of the electronic device. 
         [0081]    Hereinafter, the amount of vibration of the haptic device  20  according to the disposition location of the actuator  60  at the haptic device  20  will now be described in detail. 
         [0082]      FIGS. 7(   a ) and  7 ( b ) are schematic perspective views showing a changed disposition location of the actuator of the haptic feedback actuator according to an exemplary embodiment of the present invention.  FIG. 8  is a side view for explaining a disposition location of the actuator according to an exemplary embodiment of the present invention.  FIG. 9  is a graph displaying the amount of displacement over vibration frequency of the haptic feedback actuator of  FIGS. 7(   a ) and  7 ( b ). 
         [0083]      FIG. 7(   a ) shows an exemplary embodiment in which the actuators  60  are aligned in a row in the lengthwise direction on the display panel  22 , namely, the haptic device  20 , and  FIG. 7(   b ) shows an exemplary embodiment in which the actuators  60  are centrally disposed in parallel at the central portion of the display panel  22 . 
         [0084]    Here, the central portion of the display panel  22  may be a central portion in a widthwise direction based on the entire display panel  22  or may be a central portion (C) in the lengthwise direction. 
         [0085]    With reference to  FIG. 8 , the central portion (C) where the actuators  60  are aligned may be set to be within the range from 20% to 80% of the overall length of the display panel, namely, from one end portion to the other end portion of the display panel  20 . The other portions are set as edge portions (E) for the sake of convenience. 
         [0086]    Meanwhile, the vibration plate  40  may be selectively employed according to a required range of vibrations of the electronic device. 
         [0087]      FIG. 9  is a graph showing the results obtained by measuring the amount of vertical displacement of the haptic device  20  while increasing the frequency of vibrations by applying a contact pressure in the exemplary embodiments of the present invention. 
         [0088]    With reference to  FIG. 9 , it is noted that the displacement of the actuators  60  disposed at the central portion of the display panel  22  increases at the ratio of geometrical progression as the frequency of vibrations increases. 
         [0089]    Thus, the disposition location of the actuators  60  can be properly selectively employed in the haptic device according to the vibration requirement range of the electronic device. 
         [0090]    An exemplary embodiment in which an adhesive for the haptic device  20  and the vibration plate  40  and that of the vibration plate  40  and the actuator  60  are varied as a factor of displacement will now be described. 
         [0091]      FIG. 10  is a schematic sectional view showing bonding of the haptic feedback device according to an exemplary embodiment of the present invention.  FIG. 11  is a graph displaying the amount of displacement over vibration frequency of the haptic feedback actuator measured according to various types of bonding materials for the haptic feedback device according to an exemplary embodiment of the present invention. 
         [0092]    With reference to  FIG. 10 , an anaerobic adhesive  25  was used as an adhesive for the haptic device  20  and the vibration plate  40 , and a thermosetting adhesive  45  was used as an adhesive of the vibration plate  40  and the actuator  60 . 
         [0093]    The anaerobic adhesive  25  has properties such that it can block air, is clean, and is resistant to a vibration impact. Here, the anaerobic adhesive  26  may be a UV adhesive. 
         [0094]    Thus, in order to properly transfer vibrations as much as possible without causing a displacement on the haptic device  20 , the anaerobic adhesive  25  can be selected as it effectively transfers vibration when compared with an adhesive made of a rubber material. 
         [0095]    Meanwhile, the vibration plate  40  and the actuator need to use the thermosetting adhesive  45  that can maintain variation rigidity and has a greater adhesive strength when compared with the transfer or vibration. 
         [0096]      FIG. 11  is a graph showing the amount of displacement according to a change in the number of times of vibration measured with the anaerobic adhesive  25  and the thermosetting adhesive  45 . It is noted that the anaerobic adhesive  25  shows a remarkable increase in the amount of vibrations according to the increase in the frequency of vibrations, while the thermosetting adhesive shows firm fixing, although the amount of vibrations according to an increase in the frequency of vibrations does not greatly increase. 
         [0097]    As described above, according to the haptic feedback actuator, and the haptic feedback device and the electronic device having the same, the size of the electronic device can be reduced when compared with an electronic device employing a vibration motor, and the utilization of the internal space of the electronic device can be enhanced. 
         [0098]    In addition, because the disposition location or the length of the actuator can be variably selected according to the vibration range required for an electronic device, the present invention can be applicable to various applications. 
         [0099]    Also, because the electronic device itself is not vibrated overall, the present invention is very effective in terms of power consumption, 
         [0100]    Moreover, various feedbacks can be implemented in line with the recent advancement of user interfaces. 
         [0101]    As set forth above, the haptic feedback actuator, and the haptic feedback device and the electronic device including the haptic feedback actuator according to exemplary embodiments of the invention have the following advantages. 
         [0102]    That is, first, the size of the electronic device can be reduced compared with an electronic device employing a vibration motor, and the utilization of the internal space of the electronic device can be enhanced. 
         [0103]    Second, because the disposition location or the length of the actuator can be variably selected according to a vibration range required for an electronic device, the present invention can be applicable to various applications. 
         [0104]    Third, because the overall electronic device is not vibrated, the present invention is very effective in terms of power consumption. 
         [0105]    Fourth, various types of feedback can be implemented in line with the recent advancements in user interfaces. 
         [0106]    While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.